Copy of Project

Textile Printing

PREFACE

“Genius makes its observations in short hand; talent writes them out at length.”

Christian Nevell Bovee

As mentioned by the above quotations observing and on site viewing are a very firm

base for learning. We learn a lot more by seeing the theories than we read in books,

applied practically by the pros and by seeing how they actually put them to work.

If we mull over the significance of internship program then we will be able

to bare the facts that internship enhance one’s practical loom towards work and

provide maximum chances for learning, which will obviously help out candidate in

the practical fields. In short internship plays a pivotal role in the future sensation &

stir of the candidate.

The effective system at NISHAT was a piece of art and to see it in working

process was a treat itself. NISHAT has fine and well defined

organizational structure working effectively.

In preparation of this Report we have tried our best to provide all possible

information about the operation, function and tasks of NISHAT in brief and

comprehensive form. It also includes a brief department work during internship. We

have also tried our best to use simple and easy words and language.

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HAJVERY UNIVERSITY LAHORE

Textile Printing

Introduction

ishat is playing a significant role in the private sector by adding

value to cotton and the cotton based economy, Nishat Group ranks

among the top five business houses in Pakistan terms of sales and

assets.

NNishat Mills Limited started out as a weaving unit with 500 semi automatic

looms, later on 10,000 spindles were added, laying the foundation of nation’s

biggest textile composite project. Today, Nishat Mills Limited is largest

vertically integrated unit of Pakistan. It comprises of 173,000 spindles, 528

state of the art shuttles-less and air jet looms, a processing capacity of three

million meters and stitching capacity of more than one million meters per

month, supported by a power generation plant with a capacity of 33.6 MW.

Nishat Mills Limited is awarded the President of Pakistan’s Trophy for

Exports, being a Pakistan’s largest exporter in any category. Nishat Mills is

also certified with ISO 9001 certification and these awards reflect the quality

of service available under one roof.

Since its inception in 1951, the group has grown from a cotton house into a

premier business group. After almost half a century of undaunted success, the

group has its roots firmly planted into four core businesses i.e. Textiles,

Banking, Cement and Power Generation.

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Nishat’s Founder

A man of vision, courage and integrity, Mian

Mohammad Yahya was born in 1918 in Chiniot. In

1947 when he was running a leather business in

Calcutta, he witnessed the momentous changes that

swept the Indo-Pak sub-continent and culminated in

the emergence of Pakistan. Like many of his contemporaries, he also migrated

to the new country to help establish its industrial base; his is a story of success

through sheer hard work and an undaunted spirit of enterprise. Beginning with

a cotton export house, he soon branched out into ginning, cotton and jute

textiles, chemicals and insurance. He was elected Chairman of All Pakistan

Textile Mills Associated (APTMA), the prime textile body in the country. He

died in 1969, at the age of 51 having achieved so much in so short a time.

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Chairman

Today, Mian Mohammad Mansha, the Chairman of Nishat Group,

like his father, continue the spirit of entrepreneurship and has led

the Group to become a multi dimensional corporation, with wide

ranging interests.

Nishat has grown from a cotton export house into the premier

business group of the country with 5 listed companies, concentrating on 4 core businesses;

Textile, Cement, Banking and Power Generation. Today, Nishat is considered to be at par

with multinationals operating locally in terms of its quality products and management skills.

Chairman's Message

Firmly believing in “Growth Through Professional Management” our corporate culture is

based on decentralization, delegation of authority, encouraging the acceptance of

responsibility and inculcating quality consciousness. It is our conviction that every

successful organization is a reflection on the commitment, dedication, and team spirit of its

employees, and Nishat is no exception. Our people are all imbued with this spirit, a fact

manifested in our rapid growth and low employee turnover.

We continue to strive to be a better group today than what we were yesterday, for our

clients, for our shareholders, for our investors, for the environment, for the community and

for our employees, for it is with them that we have achieved what we have. It is with them

that we will continue to surpass our past achievements.

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Textiles

With a base of about 14 billion from textiles export sales revenues and

new investments in line. Nishat is committed to further enhance the foreign

exchange earnings for Pakistan.

The textile capacity of the group is largest in the country.The total monthly

capacity can be categorized as under;

Spinning Over 198,120 spindles into 8 spinning units.

Weaving 7.4 million meters of fabric per month (629 Looms)

Processing Produce 9 million meters of fabric /month

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Nishat Dyeing and Finishing Plant

Nishat Dyeing and Finishing Plant, with a capacity of

processing more than 3 million meters, is one of the

largest processing units of Pakistan. The unit has started

its production in February 2001 and cost of the unit to

the date is 1.5 billion rupees, with an array of most

modern machines equipped to match up ever increasing demands of market/customers. The

processing division is divided into different section to facilitate un-interrupted process flow

and to ensure quality control at all stages.

Nishat Dyeing and Finishing Plant is well equipped, well developed and has all the

latest pre-treatment machinery and modern facilities. Almost 75 percent of the chemicals

and dye stuffs used are imported from Europe, Australia and Japan, just to ensure the quality

standards at all levels and stages of processing. An independent Quality Control Department

with a strong back up of fully equipped lab to ensure quality at all levels, a separate

Production Planning Department ensures timely deliveries of stock and whole unit is lead by

a Marketing Department, which is its integral part.

There are following main departments of Nishat Dyeing and Finishing Plant.

1. Greige Department

2. Bleaching Department

3. Dyeing Department

4. Printing Department

5. Finishing Department

6. Folding Department

7. Sampling Department

8. QC LAB Department

9. Production Planning Department

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10. Marketing Department

Table of Contents1 Greige....................................................................................................................................11

1.1 Fabric Receiving:-.........................................................................................................11

1.1.1 Receiving register:.................................................................................................11

1.2 Inspection:......................................................................................................................11

1.2.1 Inspection of Greige Fabric..................................................................................11

1.3 Yarn Faults:...................................................................................................................12

1.4 Point System:.................................................................................................................12

1.5 Faults in under consideration fabric...........................................................................13

1.6 Quality of Fabric (CONSTRUCTION):.....................................................................13

1.6.1 Testing Of Greige Fabric......................................................................................13

2 Pretreatments of Textile......................................................................................................14

2.1 Singeing:.........................................................................................................................15

2.1.1 Osthoff Singeing.....................................................................................................16

2.1.2 Parts of machine....................................................................................................16

2.1.3 Fabric Entry...........................................................................................................16

2.1.4 Cloth Guiders.........................................................................................................16

2.1.5 Drying Cylinders....................................................................................................17

2.1.6 Brushing Chamber................................................................................................17

2.1.7 Singeing chamber...................................................................................................17

2.1.8 Brushing zone.........................................................................................................18

2.2 Desizing Saturator.........................................................................................................19

2.2.1 Batch making.........................................................................................................19

2.2.2 Recipe for Cold-Pad Batch in Desizer.................................................................19

2.3 Bleaching........................................................................................................................20

2.3.1 Major bleaching agents:........................................................................................20

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2.3.2 Hydrogen peroxide Bleaching..............................................................................21

2.3.3 L-Box Bleaching Plant...........................................................................................22

2.3.4 Cold-Pad Bleach Process Discussion....................................................................23

2.4 Auxiliaries......................................................................................................................24

2.4.1 Stabilizers:..............................................................................................................24

2.4.2 Wetting agents........................................................................................................24

2.4.3 Sequestering Agent................................................................................................24

2.5 Pretreatment Testing....................................................................................................24

2.5.1 Tegawa Test............................................................................................................24

2.5.2 PH Test...................................................................................................................24

2.5.3 Absorbency Test.....................................................................................................25

2.5.4 Whiteness................................................................................................................25

2.5.5 Tear & Tensile........................................................................................................25

2.5.6 Width......................................................................................................................25

3 Stenter...................................................................................................................................26

3.1 Trough............................................................................................................................27

3.2 Padder............................................................................................................................27

3.3 Drying chambers...........................................................................................................28

3.3.1 Mahlo......................................................................................................................28

3.4 Stenter Chain.................................................................................................................29

3.5 Cooling Drums...............................................................................................................30

4 Printing.................................................................................................................................31

4.1 Properties that affect the Printing:..............................................................................32

Fibers........................................................................................................................................32

4.2 Yarns..............................................................................................................................32

4.3 Fabric Construction......................................................................................................32

4.4 Pigment Printing...........................................................................................................32

What are pigments?.................................................................................................................32

4.5 The History of pigments...............................................................................................33

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4.6 Pigment Printing...........................................................................................................34

4.7 Pigment Printing Constituents.....................................................................................38

4.8 Binders:..........................................................................................................................38

4.8.1 Formulation for binders:......................................................................................39

4.8.2 Order of formulation:............................................................................................39

4.8.3 Types of Binders....................................................................................................41

4.8.4 Film formation and cross linking of Binder system...........................................41

4.8.5 Binder ET...............................................................................................................42

4.8.6 Fields of application...............................................................................................42

4.9 Thickeners......................................................................................................................43

4.9.1 Functional properties and requirements for thickeners....................................45

4.9.2 Types of Thickeners:.............................................................................................46

4.10 Ammonia:...................................................................................................................51

4.11 Urea:...........................................................................................................................51

4.12 Printing Sampling Machine......................................................................................51

4.13 Rotary screen printing:.............................................................................................52

4.13.1 Screen preparation:...............................................................................................54

4.13.2 Squeegee systems:..................................................................................................60

4.13.3 Special functions in Rotary printing:...................................................................62

4.13.4 Gluing and washing devices:.................................................................................62

5 Pigment Printing Paste Recipe...........................................................................................64

5.1 Thickener as a variable.................................................................................................64

5.1.1 Testing “Thickener”..............................................................................................65

5.1.2 Rubbing Fastness...................................................................................................66

5.1.3 Dry Cleaning Fastness...........................................................................................69

5.1.4 Washing Fastness...................................................................................................73

5.2 Binder as a variable......................................................................................................76

5.2.1 Testing “Binder” Tear and Tensile......................................................................77

5.2.2 Rubbing Fastness for Binder................................................................................78

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5.2.3 Dry cleaning Fastness............................................................................................80


5.3 Ammonia (NH3) as a variable......................................................................................87

5.3.1 Testing (NH3) Tear & Tensile...............................................................................88

5.3.2 Rubbing Fastness...................................................................................................89

5.3.3 Dry cleaning Fastness............................................................................................91


5.4 Urea as a variable..........................................................................................................98

5.4.1 Testing “Urea” Tear & Tensile............................................................................99

5.4.2 Rubbing Fastness.................................................................................................100

5.4.3 Dry Cleaning Fastness.........................................................................................102

5.4.4 Washing Fastness.................................................................................................106

6 What is color fastness?......................................................................................................110

6.1 Rubbing Fastness........................................................................................................110

6.1.1 Dry Rubbing.........................................................................................................110

6.1.2 Wet Rubbing........................................................................................................110

6.2 Washing Fastness........................................................................................................111

6.3 Dry Cleaning Fastness................................................................................................111

6.4 Tear Strength Testing.................................................................................................113

6.4.1 Single Rip Method...............................................................................................114

7 Printing Paste.....................................................................................................................116

8 Conclusion..........................................................................................................................118

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1 GreigeThe purpose of greige department is receiving, inspection, storage, and issuance.

Initially the fabric of all types bring here. Before it is stocked inspection is done and results from QC Lab are also considered. If the inspection results of greige and quality control lab are satisfactory then it is stocked by given its all identifications, i.e., lot no bin no type of fabric total no of meters etc.

1.1 Fabric Receiving:-When the fabric is received, the greige section records the specifications of fabric

received fabric receiving register.

1.1.1 Receiving register:The following detail is written in the receiving register;

Serial no. Contract no. Construction Width Receiving date Weave Blend Supplier name Total bales Fabric length Internal gate pass Lot no. are given to the fabric

1.2 Inspection: Inspection of about 10% of whole fabric takes place in greige department. Inspection

percentage may vary depending upon the quantity of fabric. If the amount of fabric is less then inspection% may increases from 10% to 50%. There are four inspection machines out of which one is also for rolling. The main purpose of inspection is to count faults in type of fabric.

1.2.1 Inspection of Greige Fabric Before the Fabric Is pretreated it is inspected according to customer requirement under the specified procedure.

Activities performed in greige section: Fabric Receiving Fabric Inspection Fabric Stocking Stitching

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Fabric Issuance Documentation

1.3 Yarn Faults: Contamination: Any fault other then the fiber of fabric is called contamination.

Mainly polypropylene, hair, jute etc. are some common contaminations. Cockled yarn: fluff or any material pressed by machine in warp more end is called

cockled yarn. It forms hard surface. Color variation: At some places color is found different then the actual one. Oily weft: When weft or pick yarn is oily then it is called oily weft. Black End: When end or warp is black may be due to oil is called black end. Count variation: In this case warp or weft may be thick or thin then the count

shown in the construction. In this case cloudy like appearance occurs. Short End: Any warp or end may be missing. Double End: In this case double yarn is found in end or warps rather then the single

one. Miss pick: Any pick or weft may be missing. Double pick: Double yarn in pick or weft is missing. Mechanical faults: Short miss pick: If pick or weft is missing at any point than it is called short miss

pick. Short double pick: In this case two yarns in pink are found for short distance. Starting mark: When loom stops and then starts gives a stain (crease) on fabric in

weft angle. Wrapping mark: It is just like starting mark but here surface become very hard on

weft side. Oil stain: It is the spot of oil in circular shape and mostly yellowish in color. Kinks: When new yarn is knocked either on warp or weft side it is pressed and

become hard and swollen. Loose ends: Warp or end comes out of fabric and not properly stitched, so it does

not look straight and forms in zig zag way. Sizing satin: It is like oily stain but more opaque then oily stain.

1.4 Point System: Length of fault Points

1-3 inches 1 3-6 inches 2 6-9 inches 3 9- above 4

This is called four point American systems. It was developed to create an understanding between customer and supplier.

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Important Points:Average 20 faults in 100 m fabric are acceptable. The distance between every fault

should 5-6 m. If these faults are very close to each other then this fabric will also reject. Suppose in 30 m 20 faults are present.

Selvedge: Selvedge is present on both sides of fabric. It is strong, hard and saves fabric from

the pressure of stitching during processing. It is of two types. Leno (L): It has free yarns on weft. Tuck in: It has not free yarns on ends.

1.5 Faults in under consideration fabric Contamination (Jute) Count variation Missed picks Polypropylene

1.6 Quality of Fabric (CONSTRUCTION):60∗60

164∗126 - 118

Here 60 and 60 are count number on warp and weft side of fabric respectively. Count no. is a Japanese system which depends upon the weight of warp or weft yarn. 164 are no. of warp per square inches and 126 is no. of weft per square inches. 118 is the total width of fabric including selvedge.

1.6.1 Testing Of Greige FabricIn Nishat mills we carried out the following testing on greige fabric.

1: Quality2: Tear Strength3: Tensile Strength4: Blend Ratio5: G.S.M of Fabric

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2 Pretreatments of Textile

Flow Chart of Pretreatment Processes

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Singeing

Desizing (Cold-pad)

Solumatic Bleaching

Textile Printing

2.1 Singeing: Singeing is the first stage in a preparation sequence. Singeing is a process of surface lint /hair/protruding fiber removal. Cotton woven fabrics would normally be singed but knitted fabric would not. The most widely used type of singeing machine allows the fabric to pass at a high speed through a naked gas flame.

Before Singeing After Singeing

Advantages that we achieve from the singeing process: Surface hairs help to trap air in the fabric when immersed in water. It takes

longer for water to enter the fabric since it must first displace the air. Singeing therefore helps to increase the fabric wet ability.

It creates a smooth surface for printing. It may be possible to print fine detail on a hairy surface but once the hair moves again after printing and fine details will become fuzzy and indistinct.

To emphasize the woven structure of fabric if that is considered desirable. It prevents a “frosty” appearance after dyeing. The projecting dyed hairs give

the fabric surface the appearance of being paler than rest the body of the fabric.

To prevent or minimize the tendency of blend fabrics to form pills. Pills are the little balls of fiber that arise on the surface of some fabrics as a result of abrasion that occurs during usage.

Singeing is continuous process carried out on dry open-width fabric. It may be done on one side only or on both sides of the fabric but in every case it is necessary to do it at very high cloth speeds. Speeds of 80-120 m/ min are typical to avoid scorching the fabric. The aim is to run at a speed which ensures that the projecting fibers will have burned down to the surface of the fabric but that there is no burning of fibers which are locked within the yarn and which are not projecting.

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Immediately after passing through the singeing region of the machine, the fabric is quenched by running it through water or a steam box to extinguish any remaining sparks and embers.

2.1.1 Osthoff SingeingOsthoff Singeing machine is composed of two parts, singeing and desizing. Their

complete specification is illustrated below.

Machine SpecificationName Osthoff-SengeSteam pressure in Drying rollers 0.2 bar 1st brushing zone 2 rollers (brush shape flat, driven by Separate motor)Brushing angle 3-5 (from the fabric surface)Singeing zone 2 burner (ceramic)Flame intensity 8-23 mbarFlame distance 10-30 mm2nd brushing zone 2 rollers (contain piles, driven by separate motor)Fabric speed 90-150m/minSaturator temp 75-85oCSaturator water capacity 900 litersSaturator fabric capacity 13-15 metersSqueezing pressure 1st 2.51bar, 2nd 0.9-1.0 bar

2.1.2 Parts of machineThe Osthoff-Senge machine consists upon the following major parts.

2.1.3 Fabric Entry Fabric entry is composed of the different free and stationary guide rollers, to guide the fabric and to open its width.

2.1.4 Cloth Guiders Cloth guiders are used to guide cloth

to its respective position and to open the width of the fabric by removing any creases present in the fabric. Pneumatic pressure is used to operate these guiders.

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2.1.5 Drying CylindersThese are two large surface, polished drums which are heated by steam. These

drums are used to dry the moisture gained by the fabric during storage.

2.1.6 Brushing Chamber In the brushing chamber two brushes remove any lose thread/yarn, fluff and raises

the fibers so these can be burnt easily. The brushed off fluff or threads are taken away from the chamber by a suction fan.

2.1.7 Singeing chamber Singeing chamber consists upon two burners. Burner singes the fabric from both

sides (face and back) so both face and back are singed twice. LPG & natural gas is used as fuel. Flame intensity is adjusted according to the quality of the fabric. Exhaust fan is used to remove hot air and burnt fibers from the chamber.The flame used is of two types:

LPG CNG

These two flames are used with air mixture in appropriate ratios. Flame temperature ranges Up to 760 0 C.

Singeing positions Fabric is singed at different positions depending upon the fabric construction. I-e

Onto free guided fabricFlame meets right-angle onto dense woven fabric freely guided between 2 rollers, recommended for natural fibers and blends weighing more than 125g/m²

Onto water cooled rollerFlame meets right-angle onto the fabric bended over a water cooled roller. Recommended for fabrics of temperature sensitive fibers, those of open-weave, blended ones weighing less than 125g/m

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Tangential singeingFlame passes tangentially over the fabric bended over a water cooled roller recommendable for fabrics which cannot tolerate direct exposure to flame and for repair of filamentation

2.1.8 Brushing zone Brushing zone consist of two rollers, contain piles. The purpose of the zone is to remove burnt projected fibers and fire sparks. A suction fan is used to remove the burnt fibers from the brushing chamber.

Singeing Conditions

Fabric speed 75m/mintNo. of burners 2Singeing position 3Fabric Temperature 125Flame Intensity 18

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2.2 Desizing SaturatorAfter brushing the fabric enter into the

saturator for Desizing. Desizing is usually is done with enzymes here. As we have done cold-pad Bleach process so we applied the Bleaching recipe in desizing bath. There are two desizing saturator in osthoff senge. Main parts of the saturators are as follows

Stainless steel compartment, single-threaded with 10, 15, or 20m fabric content

Low-friction outside bearings Jockey-roller on request, Driven upper roller on request Bath filter on request Squeezer, pressure according to need, with conventional or stabilized rolls.

2.2.1 Batch making After desizing (cold-pad) they make the batch of the fabric.

2.2.2 Recipe for Cold-Pad Batch in Desizer

Sr. No Chemical Weight g/l1 Hydrogen peroxide 182 Sodium Hydroxide 503 Sequestering Agent(NFE) 54 Wetting Agent(UPT) 55 Stabilizer (OKM) 2

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2.3 BleachingIt is the process of removal of color impurities or it whitens the fabric or yarn by

oxidative or reductively removing the color impurities. In bleaching absorbency also rose. A consistent white base fabric has real value when printing light to medium shades because it is much easier to produce shade according to desire on a consistent white background than on one that varies in amount of color impurities (yellow).Bleaching may be the only preparatory process or it may be used in conjunction with other treatments, e.g. desizing, scouring and mercerizing.

The aims of bleaching are High degree of whiteness for white goods. Even and stable white for dyed goods. Complete removal of cotton seeds and motes. No or only minimum tendering of the fiber. Technically reliable and simple operation. Economical (less chemical and energy required).

2.3.1 Major bleaching agents:Bleaching agents are compounds which are used to remove color from substances

such as textiles. In earlier times textiles were bleached by exposure to the sun and air. Today most commercial bleaches are oxidizing agents, such as sodium hypochlorite (NaOCl) or hydrogen peroxide (H2O2) which is quite effective in "decolorizing" substances via oxidation.

Oxidative bleaches are also known to degrade cellulose so the objective in bleaching is to optimize whitening and minimize fiber damage. Reductive Bleaches reduce color bodies into colorless compounds. Most textile fibers are bleached with oxidizing bleach.

2.3.2 Hydrogen peroxide BleachingIt is estimated that 90 t o 95 % of all cotton and cotton/synthetic blends are bleached

with hydrogen peroxide. It is available commercially as 35, 50 and 70 % solutions. It is stable under acidic condition but unstable and reactive under alkaline condition.

2.3.2.1 Bleaching Mechanism: The bleaching efficiency is obtained by activation of the Hydrogen Peroxide. In

alkaline medium, the reaction speed increases with the temperature. The per hydroxyl anion which is formed reacts with the colored impurities of fibers and transforms them by oxidation into soluble compounds.

Higher alkalinity increases the concentration of per hydroxyl ions which is the active species. The catalytic decomposition caused by metal ions (in particular iron and copper), is

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prejudicial to the quality of the processing, either by the waste of bleaching agent or by the degradation of the material (involving a de polymerization of cellulose and thus a loss of resistance and a premature wear down of the piece). The presence of metal particles coming from the shuttle looms can even lead to the presence of oxycellulose, resulting later in holes. This reaction is catalyzed by metal ions e.g. Cu++, Fe+++. This reaction is not desired in bleaching because it is an ineffective use of hydrogen peroxide and causes fiber damage and hydrogen peroxide can also decompose; to avoid this decomposition stabilizers are used. The per hydroxyl ion is the active bleaching agent.

2.3.2.2 Effect of PH, Time, Temperature:Hydrogen peroxide is an extremely weak acid. Since the per hydroxyl ion is the desired

bleaching specie, adding caustic neutralizes the proton and shifts the reaction to the right . Therefore:

At pH < 10, hydrogen peroxide is the major specie so it is inactive as bleach. At pH 10 to 11, there is a moderate concentration of per hydroxyl ions. PH 10.2 to 10.7 is optimum for controlled bleaching. Sodium hydroxide is used to

obtain the proper PH. At pH> 11, there is a rapid generation of per hydroxyl ions. When the pH reaches

11.8, all of the hydrogen peroxide is converted to per hydroxyl ions and bleaching is out of control.

Stabilized hydrogen peroxide does not decompose at high temperature therefore faster and better bleaching occurs at 95 to 100 0C. This feature makes it ideal for continuous operations using insulated J-boxes or open-width steamers.

Uses:Hydrogen peroxide is the bleach most widely used for cellulosic fibers [cotton, flax,

linen, jute etc.) and well as wool (Conditions should be acidic), silk, nylon and acrylics. Unlike hypochlorite, peroxide bleaching does not require a full scour. Residual fats, oils, waxes and pectin’s do not reduce the bleaching effectiveness of hydrogen peroxide. Additionally it can be used on continuous equipment. Since it ultimately decomposes to oxygen and water, it doesn't create effluent problems.

2.3.3 L-Box Bleaching Plant

Made by KUSTERSModel: 2002

OperationMaximum speed of this machine is 125m/ min.

First of all fabric from the batcher is taken to the guide roller and then to the rubber roller operated by a separate motor and then on to the winder and then in scray. When one batcher is about to end then the roller operated by separate motor is driven and the fabric is collected in the scray in order to stitch the fabric from the next batcher with the previous one in order to prevent the stoppage of machine. So the scray is basically the collection box.

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Pressure motor is basically present to produce tension in fabric and to avoid wrinkle free and folding free fabric.

From Washing TanksThen the fabric after passing through the coil roller through the scray is passed on to

the washing zone one. Rollers in the coil form remove the crease and wrinkle formation in fabric. Here in the washing chamber one hot washing with the steam is done. The temperature in the washing is 95oC. The soaping is done and then again washing is done in washing two, same as washing no. one. Then the fabric is passed through the padder roller and here water is removed from the fabric then the fabric is passed on to the FLEX NIP.

The Flex NipThen the fabric is passed on to the FLEX NIP. Here the main bleaching with the

chemicals is done. Here the fabric is treated with various chemicals. The chemicals are introduced in Flex Nip by an auto dozing system. If the fabric is to be scoured the in the same chamber the scouring chemicals are introduced instead of the bleaching chemicals. Fabric speed keeps 80 m/min.

Sr. No Chemical Weight ml/kg of fabric

1 Hydrogen peroxide 252 Sodium Hydroxide 163 Sequestering Agent(NFE) 64 Wetting Agent(UPT) 35 Stabilizer (OKM) 3.5

The SteamerAfter the flex nip the fabric is passed through the steamer in zigzag form as the rollers are in zigzag form. Here steam is applied on the fabric. The temperature of the steam is about 99.4oC. The time of passing of specific length of fabric through steam box is adjusted according to the requirement and type of fabric. This time was approximately 20 minutes when I visited this mill. Entrance and exit from steam box is the same way.

The WashingsAfter the steamer the fabric is passed through the series of hot washings. After every

two washing chambers squeezing is done by means of squeezing rollers.In the hot washings hot water is showered on the inclined fabric so, that more water is penetrated in the fabric. In the squeezing rollers the fabric is squeezed and pressed to remove the extra amount of water from the fabric. The pressure of squeezing roller is adjusted according to the degree of percentage of process uptake.

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There are mainly five washings and two squeezing zones. One squeezing zone after every two washing and again a squeezing after the next two washing. Again the pressure inside the washing is controlled and adjusted according to the requirement.

With every squeezing roller pair there is a dancing roller to control the tension in the fabric.

Drying CylindersAfter washing the fabric is passed through the drying cylinders. Inside these

cylinders is hot water for drying purpose and in between these cylinders fabric is circulated in zigzag form. At the end of drying cylinders there are two cylinders known as water cooled cylinders. Inside these two cylinders cold water circulates in order to low down the temperature of fabric which was increased during hot cylinder drying.Then again there is a scray for collection of fabric and then the bleached fabric is wound on a batcher through the delivery roller for further processes.

2.3.4 Cold-Pad Bleach Process DiscussionThis process is very simple. It is time consuming but cheap process. This process

requires 15-25 hours as Dwell time. The batch is covered with polythene in order to avoid air oxidation and to ensure good peculation; the batcher is rotated at 4-5 rpm. This process consists of two steps:

Single Step Double Step

In single step the fabric is cold padded and given Dwell time of 15-24 hours, after this the fabric is simply washed prior to drying.

In double step process the fabric is cold padded ant then given Dwell time of 8-12 hours. Since the time is short so we will have to apply bleaching recipe on bleaching plant after washing. In this process the required results are not achieved so we will have to apply bleaching recipe.2.4 Auxiliaries2.4.1 Stabilizers:` Stabilizers must be added to the bleach solution to control the decomposition of hydrogen peroxide. Stabilizers function by providing buffering action to control the PH at the optimum level and to complex with trace metals which catalyze the degradation of the fibers. Stabilizers include sodium silicate, organic compounds and phosphates.2.4.2 Wetting agents

Wetting agents are compounds that lower the surface tension of a liquid, allowing easier spreading, and lowering of the interfacial tension between two liquids, or between a liquid and a solid. Surfactants may act as: detergents, wetting agents, emulsifiers, foaming agents, and dispersants. Surfactants reduce the surface tension of water by adsorbing at the liquid-gas interface.2.4.3 Sequestering Agent

A substance that removes a metal ion from a solution system by forming a complex ion that does not have the chemical reactions of the ion that is removed; can be a chelating or a complexing agent.

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Sequestering agents combine with calcium and magnesium ions and other heavymetal ions in hard water. They form molecules in which the ions are held so securely (sequestered) that they can no longer react.

The sequestering agents prevent salts from recontaminating parts. The sequestering agents may also tie up the active chemicals in a detergent that may

decrease the cleaning efficiency and life of a wash bath. Common sequestering agents include orthophosphate, orthosilicate, and phosphates.

Sequestering agents are produced as powder or in liquid form.

2.5 Pretreatment Testing2.5.1 Tegawa Test

Tegawa test is used to find out the size percentage in the fabric. A drop of tegawa solution is dropped on the fabric and matches it with tegawa rating which is 1-9.

The under consideration fabric tegawa rating was 5-6 which is considered as very good.

2.5.2 PH TestThis test is used to find out the PH of the fabric. A drop of PH solution is dropped on

the fabric and matches it with the scale given below:

Ph Scale

The PH of the fabric under consideration fabric is 6 which lie in acidic media.

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2.5.3 Absorbency Test This test is used to find out the pick up percentage of the fabric. As we know that in

case of pigment printing complete absorbency of the fabric is not required. Because pigment is coated on the surface of the fabric without any reaction between pigment and fiber. In case of pigment printing absorbency is generally required up to 3cm.

2.5.4 WhitenessThe whiteness of the fabric is calculated by the ratio of incident light to reflected

light. Spectrophotometer is used to fine out the degree of whiteness. We used the primary light TL84 source to find out the whiteness of fabric in regular intervals.

Whiteness

Fabric length (meters)

Left Center Right

1000 75 73 753000 75 74 755000 76 75 767000 75 74 75

2.5.5 Tear & TensileTear & Tensile Strength after Bleach

Tensile TearWarp Weft Warp Weft

Force (N) Elongation % Force (N) Elongation % Force (N) Force (N)675.0 10.42 515.4 9.29 6.48 8.79

2.5.6 Width

Width

Before Bleach Width After Bleach Width Shrinkage118” 112” 6”

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Process of Stenter

3 Stenter The most universal fabric drying machine is the stenter, which is usually the most expensive and indispensable machine in the finishing. Most finishers will need at least two stenters as the majority of fabrics have to be stenter dried, or heat set, at least once to establish dimensions and properties. In the Yorkshire woolen industry this machine is known as the tenter and commonly has two or more layers for drying fairly heavy woolen or worsted fabrics. The essential characteristics of a stenter are the two driven chains carrying pins (clips) to hold the fabric edges for passage through the enclosed drying compartments. Guiding arrangements are designed for accurate pinning of the edges, with provision for over feeding the fabric to allow any required adjustment of fabric length while the width is increased to the precisely specified value. Clip stenters are useful for dense and heavy fabrics that tend to damage pins, but overfeeding is not possible. The no of drying compartments, each typically 3m long, depends on the speed required but is usually between three and eight. The tapering entry section is 5-7 m long and the delivery section another 5m to allow cooling to occur before removal for batching. A total length of 30m plus fabric feeding arrangements and batcher space is therefore common and speeds of 100m/min often achieved.

Stenters drying provides the ideal opportunity to achieve weft straightening and edge uncurling and the appropriate mechanism are fitted at the entry. Sometimes the recovery of curled knitted fabric edges is not possible and a system of edge gumming and subsequent cutting and removal is fitted. Efficiency and uniformity of drying demands attention to the air flow. A power full fan (or two) pushes air into tapered ducts and through precisely made nozzles to achieve high impact velocity at the fabric surface. The slightly cooler air must then be directed into the return circuit, through a filter and the heating section (ideally an internal gas burner or

thermoil heated section) to the fan. The Babcock Star jet nozzle system is claimed to improve performance by 15% because of its optimal air flow pattern. Air temperature in the region of 130-150 °C is used for high drying rates without excessive heat losses in the exhaust.

For optimal thermal efficiency, it is essential to monitor and control the humidity of the drying atmosphere. It is possible to do this with a fluidic oscillator developed by Mahlo and of the exhaust dampers and dramatically energy costs rise when the humidity falls below 10% Reducing the volume of cold air entering (by exhaust damper control) reduces the energy required to raise its temperature and it has been claimed that 30% savings in the energy result when humidity is increased from 5 to 10%. There is also a reduction in the rate of drying but an optimum balance can be found in the 10 to 15% region. In the future it may

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be that heat pumps will be used to maintain the optimum humidity and eliminate exhaust losses.3.1 Trough

Its purpose is to keep the chemicals so that when fabric passes through it, it picks the chemicals present in it. Its level is adjusted on the control panel so that it keeps the same amount of chemicals. When its level goes down, automatic valve starts feeding the chemicals. When it starts going above the required level, this valve stops feeding. Water jacket is present outside the trough. Chilled water from chiller is circulated inside this jacket to keep it cool because when fabric enters in the trough, it increases its temperature. And due to increased temperature, silicone emulsion will be destroyed and silicone will return to its origin form. When it happens, silicone will give spots of oil on fabric which is not removable. So we have to cool down the trough.

3.2 PadderIt is a kusters padder present on stenter-1. Its pressure of centre, left and right can be

adjusted separately. Its purpose is to squeeze the fabric so that 65% pick up is obtained. In finishing it is adjusted just like nip and no special kind of work is being obtained from it. Pressure of centre is adjusted is by hydraulic pressure and of sides is adjusted by pneumatic pressure. But monfort padders are present on stenter-2, 3 in which the side’s pressure is adjusted by pneumatic pressure. The speed of the fabric is 70m/min and the padder pressure is 170 N/cm2.

3.3 Drying chambersOn stenter-1, two drying chambers are present but not on the other stenters, these are

being used as predryers. These are used when we have a large production and we have to rum the machine at high speed. Their specification is same as that of curing.

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3.3.1 Mahlo It consists of 7 rollers. 3 of them are banana rollers and 3 consist of steel rollers of

simple type. Banana rollers are used for bowing and other 3 rollers are used for skewing. 4 small instruments are used for measuring the amount of skew and bow in the fabric and then adjusting the skew and bow rollers automatically. These instruments show reading on control panel and use the mechanism of light transmittance and reflectance. They throw light on the fabric and measure the amount of light reflected or transmitted. The mechanism of bowing or skewing is that when pressure is applied on any part of the fabric, then that part remains backward and the other part due to looseness goes forward and thus we can get rid of bow or skew can be created in the fabric. Skew is the requirement of some garments companies.

Most often it is run on manual control and we enter the required data and fix the speed of machine so that it remains fixing and don’t change during processing. Amount of moisture is shown on the panel.

Three rollers between the Mahlo and the stenter facilitate to change the flow rate of fabric according to our consent. We can change the speed of motors of these rollers to change the flow rate. It facilitates to get proper pinning of fabric.

3.4 Stenter ChainTwo types of stenters are present. One stenter has pins to hold the fabric and take it

through stenter chambers. Other stenter has chains to hold the fabric. On pin system stenter, fabric is pressed on these pins with the help of small roller fitted with the motor and then pressing by brush like roller to press completely the fabric on pins. A sensor is fitted which sense the presence of fabric. If fabric is not present, it stops the machine immediately.

Total no. of chambers in stenter is eight. Temperature of every chamber can be adjusted from control panel. The temperatures of the chambers are 120, 140, 150, 160, 170, 180 &

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180 °C. Every chamber has two motors. Half part of chamber is run by one motor and the other half by other motor. These motors circulate the heat inside the chamber. They are also

called blowers. These motors suck air from inside the chamber and then introduce this air in duck lining to heat up the fabric. Two major exhausts are fitted to exhaust the moisturized gases. Fresh air can only enter in the stenter chambers from entry and exit points of fabric. A small instrument is fitted in every chamber which has a small rod present just above the fabric to know the temperature of chamber. A Pleva is fitted in the centre of stenter to measure the humidity of air inside the chambers. Then the efficiency of exhausts can be adjusted according to the humidity of air. For width adjustment of stenter, we have four points inside the chambers. Stenter chambers are heated by thermoil. Thermoil exchanges its heat by using heat exchanger. Thermoil moves inside the small cylinder like rods and heat up the cylinder. Air moves through these cylinder and gets heated. Then it is circulated by the blower inside the chamber. Speed of fabric in stenter is so adjusted that dry fabric is obtained. At the end of stenter chambers, a blower is fitted which sucks the fresh air and through it on the fabric coming out of stenter chambers to cool down the fabric. Three small rollers are present at the end of stenter chain. These are collectively called RMS (residual moisture sensor). It measures the amount of moisture in the fabric and gives signal on the control panel. An emergency stop is present at the end of stenter chain. It consists of thread connecting with the sensor. When we press this thread, machine is stopped. Here, width of stenter chain can be adjusted as well.

3.5 Cooling DrumsThen cooling drums are present. Fresh water is circulated inside these drums. Their

purpose is to cool down the fabric. Then this fabric is collected in the trolley.

Tear & Tensile After Stenter

Tensile TearWarp Weft Warp Weft

Force (N) Elongation % Force (N) Elongation % Force (N) Force (N)675.7 11.44 535.2 7.65 7.06 7.64

Width

Before Stenter Width After Stenter Width Extended Width112” 116” 4”

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Note: After stenter skewing and bowing and width of the fabric to required extent was achieved.

Printing

4 PrintingPrinting involves localized coloration. This is usually achieved by applying

thickened pastes containing dyes or pigments on o a fabric surface according to a given color design. In particular, the viscosity of printing paste is critical. It determines the volume of paste transferred to the fabric and the degree to which it spread on and into the surface yarns. The paste must color all the visible fibers on the printed surface so it must penetrate somewhat into the yarn structure. If the paste is too thin, it will spread; giving poor print definition and penetrate too far into the yarn decreasing the color yield.

Printing was originally done by hand using wooden blocks with a raised printing surface, such as children do potato printing. The two main techniques used for transferring the printing paste onto the fabric involves engraved rollers carrying printing paste in the recesses corresponding to the color pattern or screens with open mesh in the pattern areas there will be one roller or screen contacting the fabric surface for each color to be printed.

The most important printing method today is pigment printing. This involves printing the colored pattern onto the fabric surface and curing the printing areas by heating in the air. The print paste contains the colored pigments and a binding agent. on curing in hot air, the binder forms the solid film of transparent polymer that hold the pigments in the surface of yarns.thr great advantage of pigment printing is that the fabric does not require washing after the fixation process. Soluble dyes used in printing the fabric are of the same type as those normally used to dye it a solid color. Apart from in pigments printing the usual sequence of operation in printing, drying, steaming and washing. Dyes for printing must have high solubility because there is only small amount of water in thickened print paste and after drying the dyes must re-dissolved in a limited amount of condensed steam. The paste must dissolve dyes to allow their diffusion into the fibers. It will also contain all the other required chemicals for fiber wetting and dye fixation. The washing removes thickening agent, unfixed dyes and other auxiliary chemicals from the fabric surface. During washing it is critical, that the dyes removed do not stain any white ground or other printed areas. For this reason, the dyes for printing must have relatively low molecular weight so that their substantivity is not very high. When a manufacture sells the same dyes for both dyeing and printing the product formulation will be invariably different.Before the modern methods of textile printing are discussed in detail .Some specific information about textile material must be covered. The properties of fibers, yarns and fabric construction impact the textile printing processes as well as the characteristics of the final printed product.

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4.1 Properties that affect the Printing:Fibers

Dyes are fiber specific, therefore dyes are chosen for printing based on the fibers, which compose the textile fabric. For example a 100% cotton cab is printed with reactive dyes, vat dyes or any dye which works for cotton. Alternatively a cotton/polyester blend requires two type dye combined in a print paste. One type is for cotton fibers such as reactive and one type for the polyester fibers, such as disperse. Textile pigments may also be used. They are not dyes but colorants and require a gum or binder to fix them on the surface of the textile fibers. Unlike dyes pigments are not fiber specific. Pigments work equally for 100% cotton with many other blends.4.2 Yarns

The type of yarn construction also has an influence on textile printing. Because print color is applied on one side of the fabric, the evenness, brightness and depth of color is very sensitive to hairiness, twist and luster of the yarn. For instance the higher the yarns luster the

brighter the printed color. Fiber luster can also influence the appearance of the printed design in much the same way. If yarns are highly twisted, they may not allow print paste to penetrate deeply into the yarn bundle and this yield poor print colorfastness. Additionally, fine to medium yarns generally are easier to print than large bulky yarns or novelty yarns (towels etc).4.3 Fabric Construction

Fabric construction properties also impact the final properties of the printed fabric as well as the printing process itself. For example, woven fabrics are easier to print than knit. The main reason for this statement is that typically woven fabrics are much more dimensionally stable than knit. Fabric distortion or shift is a major contributor to out of registration print or misprints in multicolor textile prints. Because woven’s are interlacing of yarns while knits are interlacing of loops of yarns, there is wide variety of knit fabric structures with varying dimensional stability properties, however woven fabrics are generally stable. Also fabrics with flat surface print more easily than fabrics with pile surface the good example of this difference is to compare the typical printing process for flat sheets with bath towels. Sheets are normally printed on flat or rotary printing machines and typically require a single squeegee stroke for printing process. In contrast bath towels are printed on flat screen printing machine and may require as many as four squeegee strokes to force print color down into the fabric pile. Additionally thin or sheer fabric construction may present printing problems compared to thicker fabric construction composed of same fiber content.

4.4 Pigment PrintingWhat are pigments?

The word ‘colorant’ is defined in dictionaries as ‘a substance used for coloring’ and it can therefore be used to describe both dyes and pigments. Since this chapter is concerned only with pigments it is necessary to find a criterion for deciding whether a given colorant should be treated as a pigment or a dye. In practice this is not as simple as it might seem.

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One widely used criterion is that of the solubility of the colorant in the material which it is being used to color. If it is insoluble, it is a pigment; if soluble, it is a dye.

The criterion of solubility is insufficient in itself, however. The same colorant can sometimes be a dye and, in other applications, a pigment. Vat dyes are an example of this. They were originally developed as dyes for textiles, but later were prepared in a different physical form for use as pigments. Indeed, it may be argued that since vat dyes are water insoluble and to get them to diffuse into fibers they must first be reduced, they should not be considered as dyes at all, but as pigments. Again, the aqueous solubility of many disperse dyes is so low that various devices have to be used to induce them to diffuse into polyester fibers. From all of this, it is fair to say that there is no infallible simple criterion for deciding whether a colorant is a dye or a pigment. It is always necessary to take into account the actual use to which the colorant is being put.

A further, and most important, difference between pigments and dyes is that pigments are used as colorants in the physical form in which they are manufactured. Here, physical form means both the crystal structure and the particle size distribution of the pigment. The physical form of dyes is becoming of increasing importance as methods of handling them become more automated. In most dyeing processes, however, the dyes are first dissolved in water and their physical form is thereby destroyed. Thus physical form is not generally of such overriding importance as it is in the case of pigments.

Because of the requirements of insolubility in water, in organic solvents and in the medium that it is being used to , the application processes for using pigments are quite different from those for dyes. Coloration with pigments is essentially a process of dispersion of solid particles of the pigment in a semi-solid medium.

Entire technologies are involved in each of the three largest applications of pigments, which are as colorants in paints, plastics and printing inks. Each of these media is composed mainly of organic constituents and the broad general rule that ‘like dissolves in like’ gives rise to considerable technical problems in some cases, particularly where entirely covalent organic pigments are being used. However, since some ED pigments are inorganic, as are all white pigments, many problems of migration and bleeding can be solved by changing from organic to inorganic pigments.

The chemical nature of most organic pigments is closely similar to that of the synthetic dyes that have been discovered during the past 150 years. In fact, with the exception of the phthalocyanines, almost every chemical class of pigments has been developed first for dyestuff use. There are some signs that this may not continue to be the case, with the development of some new organic pigments for specialized uses. Finally, passing mention must be made of the two most important organic pigments in our world, both natural products. These are chlorophyll and hemoglobin, which are absolutely vital in the strict meaning of the word, but only chlorophyll has found a commercial use as a colorant in food preparation.

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4.5 The History of pigmentsThe discoveries of archaeologists indicate that the first pigments used by mankind,

mainly to decorate both himself and his possessions, were the earth pigments. These are widely distributed throughout the world, are highly resistant to decomposition by heat, light and weathering, and indeed without these properties would not have survived through the centuries.

Earth pigments were probably first recognized simply because their stood out when hard lumps of rock were examined. Such rocks were broken up and the desirable ED bits picked out. The ED pigments were then ground to a fine powder and blown onto the painting surface using a hollow tube, or mixed with fatty materials to form a kind of crude paint that was applied with the fingers or a reed. The prehistoric cave paintings found in parts of Spain and France were made in this way. Examples of such earth pigments are the bright red pigment vermilion (mercury sulphide), the yellow orpiment (arsenic trisulphide), and the green malachite (basic copper Carbonate) and the blue lapis lazuli (natural ultramarine). There are many natural sources of white pigments such as chalk and kaolin, while black pigments could be obtained as charcoal from incompletely burnt wood and as soot in smoke from burning oils. For many centuries, pigments have been derived from the matters found naturally occurring in many plants and even in some animals. Examples are the red pigment madder and the blue indigo, both extracted from plants, cochineal and lake both from insects, the much-prized Tyrian purple derived from certain shellfish, logwood extracts ranging in from red to brown or black, depending on the precipitant, and finally sepia obtained from cuttlefish. The methods used for making pigments from these and other natural dyes were more like recipes than scientific procedures and were probably derived from the work of alchemists and herbalists. The former spent their lives trying to prepare gold by dissolving all kinds of cheap substances in acids and then re-precipitating them (hence their discovery of many precipitants), while the latter sought to extract compounds of medicinal value from plants and some of their extracts must have included natural dyes. Among the precipitants employed were tannic acid, tartar emetic, fatty acid (Stearic, oleic) soaps, sulphonated oils (Turkey red oil), ‘earth lakes’ (mixed natural silicates), phosphates, casein and arsenious acid. The fastness properties of these pigments were relatively poor, both to water and to light. Furthermore, the of the pigments made by these methods largely depended on the particular precipitant or combination of precipitants used, a fact also exploited by medieval dyers to extend the range of s that they could produce from the very limited number of natural dyes available to them. Many of the methods for making these pigments are of historical interest only,

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4.6 Pigment PrintingRotary screen resin-bonded pigment printing is by far the most important printing

technique because of its simplicity and low cost. Pigments have no substantivity for the fiber. They are held on the fabric surface in a film of a suitable polymeric binding agent. After printing, heating the fabric for a short period cures the binder. No additional processing is required the main advantage of this printing method. There is no penetration of into the fibers. The binder holds the pigment on the fabric surface by adhesion to the fibers. It tends to stiffen the fabric in the printed areas. This effect is hardly noticeable for small designs since the large unprinted areas retain their flexibility. The pigments used have excellent fastness to light. The technique is applicable to all types of fibers but adhesion of the binder is usually best for hydrophilic fibers such as cotton. For dark s on polyester and acrylic fibers, the fastness to washing, dry cleaning and rubbing may only be fair.A typical pigment print paste contains a considerable number of chemicals each of which has a specific role to play. The paste may include ED pigments, binder cross linking agent, thickener, flow moderator, weak acid curing catalyst, softener, defoaming agent, water absorbing chemicals or humectants such as urea or glycerol, and emulsifying agents. Chemical suppliers often make two separate partial mixtures of appropriate chemicals. These are stable and only require simple combination before printing. Apart from carbon black and titanium dioxide for black and white respectively, metal powders for special effects, the ED pigments used are organic

Compounds synthesized by the dye manufacturers. They belong to the same chemical classes as soluble dyestuffs (azo, anthraquinone, phthalocyanine) but have no ionic groups. The binder for a water-based print paste is typically a copolymer produced by emulsion polymerization of a mixture of monomers such as butyl acrylate and acrylonitrile, or of styrene and 1, 3-butadiene. During drying of the printed zones, the particles of swollen binder gel coagulate on the fabric surface and coalesce into a coherent film. By regulating the monomer composition and the degree of polymer cross linking the binder will give a film with the desired elasticity and solvent, light and washing fastness. One method of promoting cross linking is to incorporate into the polymer a small amount of co monomer with a residual reactive group such as N-methylolmethacrylamide. During curing, the N-methylol groups along the polymer chains undergo intermolecular condensation reactions producing a number of cross links (Figure 23.7). This is called internal cross linking. Since the condensation reaction generates water, and is reversible, dry air is used for curing rather than steam. The cross links are, however, reasonably stable to hydrolysis during mild washing and are not present in sufficient number to produce a rigid film. They ensure good film stability, little swelling of the film in dry cleaning solvents and improve the adhesion to the fiber surface. Cross linking can also occur by adding to the paste an agent capable of reacting with the binder polymer during curing. These are external cross linking agents. Nmethylolmelamines or their methyl ethers are typical examples. The N-methylol groups can react with groups in the binder polymer or with the fiber as well as with other chemicals in the paste such as thickeners (Figure 23.7). External cross linking is better for printing on synthetic fibers because of the improved adhesion of the film produced. The condensation of N-methylol compounds requires an acid medium and the pigment print paste will therefore

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have an added weak acid such ammonium dihydrogen phosphate. This compound causes reduction of the pH of the print film during curing, promoting cross linking.

Internal and External Cross linking of Pigment during Curing

The print paste must contain a thickener to provide the correct viscosity and flow. Pigment printing pastes should have pseudo plastic flow. The shear stress developed by the squeegee reduces the paste viscosity so that it flows easily through the screen. Once the shear decreases, however, it becomes viscous again and does not penetrate far into the fabric surface. This avoids sticking the yarns together with binder and hardening the fabric surface. Oil-in water emulsions give good results. These consist of about 70% white spirit hydrocarbons and 30% water with a small amount of non-ionic emulsifying agent

After drying, there is no solid residue on the fabric surface as the emulsion thickener completely evaporates during curing. The hydrocarbons used in oil-in-water emulsions may be released to the environment, however, and their use is in forced decline. Carbohydrate gums are not usually suitable for use in pigment printing because of the ready reaction of their hydroxyl groups with Nmethylol compounds. Fortunately, colloidal aqueous solutions

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of polymers such as polyacrylic acid have similar rheology to the oil-in-water emulsions provided that the carboxylic acid groups dissociate. Rheology is the science of the deformation and flow of materials. Addition of ammonia produces the ammonium salt of the polymer. The repulsion of the negatively charged carboxyl ate groups’ causes the polymer chain to open out and the polymer particles swell considerably.

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Some commonly used pigments

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4.7 Pigment Printing ConstituentsPigment printing paste consists of following constituents.

1. Binder2. Thickener3. Ammonia4. Urea

4.8 Binders:A product of high molecular weight macro molecules which is capable of forming a

three-dimensional film used to hold the pigment particles in place on the surface of a textile substrate thus forming a three dimensional linked network. These high molecular weight macro molecules are mainly constructed from simple monomers by polymerization. Binders only form link between the pigment and the fibers. Binders are not necessary when using dyes very important in determining fastness.Some general consideration required for an ideal binders.

Strength: Strength of the fabric is closely linked with the strength of the applied binders.

Adhesion to Fibers: The adhesion strength of the binder-to-fiber bond has to be considered.

Extensibility: Degree of cross linking should be moderate to prevent vigorous bonding of the macro molecules to preserve extensibility

Flexibility/handle: The some movements of fibers should be allowed, especially when a soft hand is desired.

Elastic Recovery: To avoid the permanent deformation of fabric, good elastic recovery is required under strain.

Resistance to aging: The binder should be stable and not be degraded in the fabric during storage and use.

Resistance to washing/ Drying cleaning: The cross linked binder film must be fast to washing/ dry cleaning because fabric requires resistance to wear, washing & dry cleaning depending on their end use.

Economical: Minimizing the cost is an ongoing requirement. Other special requirements: Such as Flame resistance, resistance to chemicals, air,

oxygen, light, heat etc.

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4.8.1 Formulation for binders:Ingredients:

Since many ingredients are involved and many different possibilities exist for different end-uses so the formulation of binding solution is an art. Some of the characteristics, and the types of formulation agents utilized to obtain them include the following.

Surfactants: offer improvement in binder adhesion, stability, and ability to be converted into foam.

External cross-linkers: Provide cross-links with binder polymer to provide improved performance. The cross linker, which has multi-functional groups, is generally added to increase crosslink density and to improve durability and resistance to deformation.

Defoamers: Utilized to minimize foam in processing Repellent agents : Convey water or oil repellency Salts: Added to impart low flame response properties and to convey antistatic

properties Thickeners: Added to control the rheology of the binder liquid Catalysts: Added to facilitate curing and to promote cross-linking Acids and bases: Added to control pH of the latex Dyes and pigments: Provide color to the binder and fabric Fillers: Added to reduce binder tack and to lower cost Optical brighteners: Added to increase whiteness The purposes of wetting agents, mainly nonionic or anionic surfactants, are to enhance

binder penetration through fabric, improve the affinity between binder and fibers. 4.8.2 Order of formulation:

The order of adding ingredients into a binding bath is extremely important; the compatibility of ingredients should be confirmed. The milky white color of most binders impedes a check on the white-color indication of non-compatible ingredients, so most ingredients are first added to the dilution water. After the compatibility is assured, binders are added and then thickeners added to adjust viscosity. For the stability of the binding solution, catalysts are added just before application. Some water may be added to reach a desirable solid level. The summarized order is as follows:

Most ingredients Latex binder Thickener Catalyst Some water, and the others, such as dyes and pigments, fillers, clays, optical

brighteners, sewing aids, etc.Classification of Binders

Binders can be classified into several categories based on the following1. Polymer chemical structure.2. Functionality.3. Type of curing reaction.

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Classification based on chemical structure:On the basis of chemical structure there are three main kinds of binders: 1. Butadiene copolymers.2. Acrylates, and3. Vinyl copolymers.

Butadiene Copolymers: Acrylic acid derivatives. Vinyl copolymers.

Classification based on functionality:The functionality of binders is present in the functional groups attached to polymer

chains, which influences wet and solvent properties. To modify binder properties, copolymerization with a small amount of monomers with special functionality is performed. The main functionalities in binders are:

Carboxyl functionality Amide functionality N-methyl amide (NMA) functionality

Classification based on type of curing reaction:The classification on the basis of type of curing reaction refers to crosslink ability of

binders, which is related to reaction with Curing resins, Cross linking agents. The most common curing resin is melamine formaldehyde condensate resin involving

reaction of n-methylol groups.

Non-crosslink able polymersThe polymers do not contain any of the functional groups. They cannot crosslink,

even with external curing resins.Crosslink able polymers

The polymers contain acid or amide functional groups. They can react with added curing resins, but the degree of cross linking is limited.Self-cross linking polymers

The polymers contain n-methylol functional groups. They can react with themselves, and a high crosslink density can be obtained by adding curing resins.

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4.8.3 Types of BindersThe following comparison of binder chemical types provides an indication of the

relative performance, as well as the advantages and disadvantages of each type of binder. As indicated, the binder properties can be modified considerably by the presence of co-monomers.

i. Acrylic:ii. Striated Acrylics.

iii. Vinyl Acetate (VAC): iv. Vinyl Acrylics: v. Ethylene Vinyl Acetate (EVA):

vi. Styrene-Butadiene (S/B, SB, or styrene butadiene rubber): vii. Polyvinyl Chloride (PVC):

viii. Ethylene/Vinyl Chloride: 4.8.4 Film formation and cross linking of Binder systemFilm formation

After the application of binders to the textile their comes a fixation process during which the applied binder system crosslink's. When the prints are dried the binder presents forms a film. There are two stages are involved in the film formation process:

1. Coagulation 2. CoalescenceDuring the very first stage in film formation i.e. coagulation, water and surfactants are

removed from the binder by absorption and evaporation. During this the dispersed solid coagulates to form a gel like layer which have very poor solidity & adhesive properties.

Where as in coalescence stage the gel particles flow together to form a continuous film.

Cross linkingElasticity and improved adhesion of the film to the substrate is achieved by cross

linking. The cross linking reaction produces covalent bonds which are insensitive to hydrolyzing agent i.e. washing liquors, body sweat and industrial atmosphere. The cross linking reaction should only be activated during fixation & not while the binder and printing paste are in storage.

The simplest cross linking reaction is condensation of carboxyl groups with hydroxyl group of film forming macro molecules. The disadvantages of this process is that it require high temperature and acidic media so there is always a risk of yellowing also ether linkage is formed which is sensitive to hydrolysis.

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4.8.5 Binder ETAcrylic pigment-printing binder for direct, discharge and resist printing. The prints

are fast to dry cleaning, have a pleasingly soft handle and excellent all round fastness properties.Nature: Aqueous dispersion of a thermally crosslink able acryl ate copolymer.

Physical form: Milky, cloudy, slightly viscous liquid.Storage: When stored correctly, in sealed containers, Helizarin Binder ET has a shelf life of 12 month after product has been removed, opened drums must be properly resealed, because the product tends to form a skin when it is exposed to the air.

Properties:

Density (20.c): Approx. 1.02 g/cm

Boiling point: Approx. 1 00o CPH: 7 - 9.Solubility: Miscible with water in all proportions.Action

Helizarin Binder ET permits the production of prints with an excellent standard of fastness; including fastness to dry cleaning. The binder is used in direct printing and also in discharge and resist printing. Prints produced with Helizarin Binder ET have a pleasingly soft handle and are resistant to ageing. Print pastes that contain Helizarin Binder ET often have a higher viscosity, with the same amount of thickening agent, than those prepared with other binders. This effect is particularly pronounced in aqueous systems and can sometimes permit significant savings in the amount of synthetic thickening agent that is necessary (e.g. Lutexal HP or HSD). In pigment-printing systems that contain white spirit, increasing the concentration of Helizarin Binder ET frequently produces an increase in viscosity, which also permits a reduction in the amount of Lutexal needed. Helizarin Binder ET is also particularly suitable for use in foam printing and for printing with pearlescent pigments.Application In conjunction with the Lutexal types, Helizarin Binder ET can be used in both emulsion and aqueous pigment printing systems. The print pastes have very good running properties Of particular interest is its use in conjunction with Helizarin Binder TW, a combination that gives very soft prints with a high standard of fastness. When Helizarin Binder TW is used, the amount of white spirit should not 200-250 g/kg print paste.Preparation of a pigment thickening

The requisite amount of thickener is added to the water and the mix homogenized with a high-speed stirrer for 8-10 minutes; if necessary, antifoam (e.g. 0.5-1.5 g/kg Defoamer TP) is then stirred. With low-solvent stock pastes, the next addition is that of the white spirit, followed by the Luprimol SIG or SE. Finally, the Helizarin binder ET is stirred in and the whole mix homogenized for a further 5-1 0 minutes.

4.8.6 Fields of applicationColored prints, matt white and matt colored prints on white and dyed grounds; flock

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Textile Printing

printing; bronze printing; printing with pearlescent pigments such as Iriodin (E. Merck, Darmstadt); foam printing.Resist printing: SuitableDischarge printing: Suitable

Helizarin Binder ET has good compatibility with the auxiliaries normally employed in pigment printing and can be mixed with other Helizarin binders in all proportions. If it is necessary to store the print pastes for an extended period, it is advisable to cover the drums with plastic film or pour a thin layer of white spirit over the surface of the paste; this can be readily stirred into the paste when it is next required for printing.

Should the viscosity become too high when the Lutexal HP or HSD is stirred into the water, the Helizarin Binder ET can be added right at the beginning.

The pH of the print pastes should be at least 7.5-8. Lower values must be corrected by adding ammonia.

Subsequent adjustment to the viscosity is possible if required. The viscosity of aqueous pastes can be increased by stirring Lutexal HP or HSD direct into the paste. Pastes that contain white spirit are thickened by adding 0.5-2 g/kg Lutexal HVW. The viscosity of pastes based on Lutexal HP or HSD can be reduced by stirring in small amounts of an aqueous solution of diammonium phosphate or ammonium sulfate.Fixation

Hot-air fixation produces the optimum standard of fastness. The following conditions are recommended: 4-5 min at 150 °C or 3-2 min at 160-170 °C.

With high-temperature steam, the print should be fixed for 5-7 min at a minimum temperature of 160 °C. This method of fixation also produces a good standard of fastness, but still somewhat below that shown by prints fixed in hot air.Safety

We know of no ill effects that could have resulted from using Helizarin Binder ET for the purpose for which it is intended and from processing it in accordance with current practice. According to the experience that we have gained up till now and other information at our disposal, Helizarin Binder ET does not exert any harmful effects on health, provided that it is used properly, due attention is given to the precautions necessary for handling chemicals, and the information and advice given in our Safety Data Sheet are observed.

4.9 ThickenersDyeing is done through impregnation and the liquor density is very low to facilitate

proper impregnation however since printing is a controlled process and solution is applied on fabric in localized way, so there has to be a way to control the viscosity of the solution to facilitate the application and handling of the liquor on substrate. Viscosity is one of the most important process variables in printing.

Thickness of the paste basically helps to restrict the dye application confined to a specific area and to produce a print or design on the fabric. To make a multi-colored printed design on a cloth, it is necessary to sharply localize color in the restricted printed area or areas only, i.e. well within the boundaries of the print design and prevent color from spreading and defusing beyond the sharp outline of the print. To achieve this, the dye is used

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Textile Printing

in a suitably thickened print-paste, rather than a simple aqueous solution as required in dyeing operation. A print-paste contains suitable dye, and several textile-printing auxiliaries.

They are characterized by undergoing marked macromolecular swelling in solution due to salvation (hydration in aqueous systems). While the principal role of thickening agents is to increase the viscosity of print pastes or pad liquors, certain other properties are also of importance, such as stability and rheology of the print paste, adhesion and brittleness of the dried thickener film, the effect on color yield and penetration, ease of preparation and removal, and not least cost.

his is best understood by comparison with simple liquids such as water or alcohol, which show Newtonian flow behavior. The apparent viscosity of Newtonian liquids does not change when a shear stress is applied. All

thickening agents, however, are highly viscous in a static state but apparently show reduced viscosity when a shearing force is applied. They must flow under shear to allow transfer through the screen, and then resume high viscosity when the shear is removed so that colorants remain where they have been deposited. Most thickening agents are of the shear thinning type the apparent viscosity progressively decreasing as the shear rate is increased. It is important that this change is reversible, viscosity returning to its original level as soon as the shear is removed. In some cases, shear thinning may not begin until a certain critical shear has been applied Thixotropic fluids show time-dependent effects in that apparent viscosity depends on both the rate and duration of shear, the return to original viscosity being delayed. The opposite of shear thinning is shear thickening, often referred to as dilatants behavior; such behavior is clearly not suitable for textile printing.

T

Print pastes may be thickened by any of the following methods A relatively low concentration of a long-chain thickening agent A relatively high concentration of a shorter-chain thickener or one having a highly

branched structure An emulsion A finely dispersed solid such as bentonite (derived from clay).

Thickening agents can be of natural or synthetic origin. Various natural gums and starches have been used traditionally in many printing styles. The materials from which they are extracted are valuable sources of foodstuffs, so availability and cost can depend on fluctuating demand from the food industry.

The properties required of an ideal thickener can be summarized as follows:

Compatibility with colorants and other auxiliaries Adequate solubility and good swelling properties in cold water Good washing-off properties High degree of purity and conformity to standard Non-dusting Biodegradable Non-toxic

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Textile Printing

Manufactured from replenish able raw materials. Viscosity Stickiness Plasticity and several other desirable properties to the print-paste.

The use of a thickener also results in an improved coverage of the fabric and localized penetration of the dye into the cloth, without spreading and maintaining a sharpness of the design.

It provides adequate viscosity for printing which restricts the flow properties of print paste to avoid spreading of color. Thickeners affect print quality in terms of depth of color, brightness, and sharpness of prints. It is necessary for pigment printing paste to be thyrotrophic, i.e., its viscosity should decrease under shear and redevelop when shear is removed, so it can be applied on the textile material easily but with limited penetration.

4.9.1 Functional properties and requirements for thickenersSome of the important functional characteristics of a good print-paste thickener for

textile printing industry are mentioned below. 1. A thickener is generally a high molecular weight natural or synthetic polymer, which being soluble or dispersible in water, is also called a hydrocolloid and produces a viscous, colloidal solution. Most of the currently used thickeners are based on soluble polysaccharides, but very few thickeners are also synthetic hydrocolloids. 2. A good thickener should be able to impart to the print-paste, a required amount of stickiness (without much tackiness), elasticity and viscosity, so that it can be used in machine or hand printing process. It is desirable for the thickener to provide non-Newtonian, shear-thinning rheology (viscosity and flow-property) to the paste, so that it becomes thinner with shear i.e. when a force is applied by the squeegee or by the roller in machine printing. When a shearing force is withdrawn, the paste should again thicken to maintain sharpness of the print. 3. The thickener, holding the dispersed or solubilized dye particles, should have low affinity for the dye, compared to the fabric being printed, so that the dye transfer from the print paste to the fabric is maximum. The film produced after drying of the print-paste on the fabric should not be brittle and should not flake out. 4. When the dye has been transferred to the fabric, the thickener, by virtue of its property to bind and immobilizing water prevents the migration and diffusion of dye to the surrounding area on the fabric, till the dye is “Fixed” on the fabric. This gives desired sharpness to the print. The color-yield is high due to the low affinity of the thickener for the dye. 5. After fixation of the dye on the fabric, a good thickener should be easily and completely washable from the cloth, so that the printed fabric does not get a harsh feel due to the presence of still remaining thickener on the cloth.

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6. A thickener should impart stable viscosity to the print-paste, over a reasonable working period. Since the polysaccharide thickeners in solution are subjected to bacterial fermentation, viscosity stability is generally achieved by use of suitable and safe preservatives. The use of a safe and permitted preservative is even more important for export grade cloth. 7. Compatibility of the thickener towards the dye and other auxiliaries being used in the print-paste is an important factor. Non-ionic thickeners are generally compatible to most dyes and auxiliaries used, irrespective of their ionic nature, but ionic print-paste additives may not be compatible to oppositely charged thickener. Synthetic thickeners e.g. polyacrylic acid salts, though less frequently used, have poor electrolyte compatibility and may lose viscosity in presence of salts. In practice, a thickener should not cause choking of screen, during printing. 8. Finally and the most important aspect, from economical point of view is that the thickener should be cheap and have dependable supply of quality product over a period of time.

4.9.2 Types of Thickeners:Thickeners on the basis of their existence can be divided into two main categories, i.e.

Natural thickeners Synthetic thickeners Emulsion thickeners

4.9.2.1 Natural thickeners:Natural thickeners are those which exist in nature and are used in the form in which

they are extracted or slightly refined form. Natural thickeners are derived from plants by extraction from part of the plant itself or from a plant secretion; their biosynthesis is now a possibility. These products are generally polysaccharides and are thus closely related to cellulose.

The source of natural thickeners may be classified as Plant seeds, which contain starch or similar products as a food reserve and may be

cultivated for industrial use such as guar. Sea weed, the natural source of alginates.

Plant gum exudates, of which the best known are gum Arabic and gum tragacanth.

The cultivation of selected micro-organisms, carried out under controlled conditions, converting waste carbohydrates into useful polymers such as xanthan.

Cellulose pulps, from which cellulose ethers are produced.

Alginates: 46


Textile Printing

Alginate is the most popular of the dye thickeners. Alginate is extracted from brown algae, a type of seaweed. Different lots of sodium alginate will be more or less thick than previous lots, so you must experiment to see how much you need to use. The principal carbohydrates component of brown Phaeophycae seaweeds is alginic acid. Different carbohydrates, agar and carrageen, are found in red seaweeds. Sodium alginates have become very important for print paste thickening because of their ready solubility, even after high temperature fixation treatments. They are especially important for pastes of reactive dyes because the extent of interaction is very small. This is due to the absence of primary hydroxyl groups and to the repulsion of dye anions by the ionized carboxyl groups of the polymer under alkaline conditions.

The stability is good between pH 4 and pH 10, but gels are formed above pH 11.5 and below pH 3.5. Buffered alginates are sold for use in strongly alkaline conditions. Alginate pastes are compatible with cellulose.

Gum ArabicWounds in the bark of acacia trees exude a gum that has interesting properties. The polysaccharide in the gum is extremely soluble in water (50%) and shows Newtonian behavior. Its structure is that of a 1:3 galantine (coiled) chain with numerous side chains, including glucuronic acid units, of two, three and four unit lengths. Molecular association of such a structure is impossible, so that hydration and solubility are readily achieved and no orientation of the molecule occurs under shear.

Gum Arabic has been used as an adhesive more than as a thickening agent, for which purpose concentrations as high as 40% may be required. Mixing with starch is not recommended as the polymer may separate.

Karaya gum (20%) has been used as a cheaper alternative. Crystal is a pre swollen and purified material made from vegetable gums such as Karaya, to be readily soluble and more reproducible in properties than the original gum.

Gurm GumGuar gum is another thickener that is commonly used (in more purified form) in

foods. It is used to thicken the caustic paste used to make patterns on mixed fibers.

4.9.2.2 Synthetic thickeners:The synthetic thickeners are obtained by copolymerizing, according to different

methods, unsaturated olephinic acids with a multifunctional unsaturated monomer as a curing agent. Polymers based on acrylic acid have been use as thickening agents based on them came into prominence in textile printing

The thickeners also find their greatest use in pigment printing. Their biggest drawback is their sensitivity to electrolytes, although this is less of a problem in pigment printing than in printing with dyes.

The sensitivity of poly (acrylic acid) to electrolytes can be reduced by copolymerizing with acrylamide [A], although only relatively small proportions can be incorporated before deterioration in thickening efficiency occurs.

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Textile Printing

Two important and interrelated parameters for acrylic thickeners are relative molecular mass and degree of cross linking. Simply increasing the molecular mass of linear poly (acrylic acid) yields thickeners that give stringy pastes unsuitable for use in printing. Hence a degree of cross linking is necessary to minimize stringiness by decreasing the water solubility and promoting dispensability.

The balance of molecular mass and degree of cross linking influences other properties, such as degree of penetration, levelness of ground colors and sharpness of the print.

These products are usually supplied to the printer as partially neutralized polyacids. Further neutralization is carried out by the printer when making up the print pastes. This neutralization is often a critical process. For certain applications, as with resin-bonded pigments, neutralization is carried out with ammonia. This has the advantage that during subsequent baking the ammonia is driven off to liberate the free polyacid, which then catalyses activation of the resin binder. In other cases neutralization is carried out with nonvolatile alkalis such as sodium hydroxide. It is particularly important to use the latter in reactive printing, since ammonia would be evaporated off during fixation leading to a lowering of pH and consequently poor fixation. Moreover, reactive dyes can be deactivated by reaction with ammonia to form their non-reactive amino derivatives.

The commercial success of acrylic thickeners in pigment printing is attributable to the fact that they can be designed to give properties very similar to those of emulsion thickenings. These were previously the only systems used in pigment printing. It is important to realize that an acrylic thickener intended for use with pigment systems may be unsuitable for use with dyes. This is because commercial thickeners, available as solutions, emulsions, liquid dispersions or powders, often contain additional chemicals to improve their stability and performance in particular systems.

For pigment systems, for example, the thickener may also contain additives (surfactants or polyelectrolyte dispersing assistants), which not only modify the behavior of the acrylic thickener but also assist dispersion of the pigment Surfactant additions are undesirable with reactive dyes because they promote color bleeding, whilst the ammonia is undesirable because of deactivation of reactive groups, the lowering of pH that occurs by its evolution

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Textile Printing

during the fixation process and the subsequent difficulty in washing-off of the residual thickener, now bereft of its solubilising ammonium ions.A major drawback of synthetic thickeners when used with dyes is their sensitivity to electrolytes. Most soluble dyes behave as highly ionized electrolytes and disperse dyes contain anionic polyelectrolyte dispersing agents unless they have been formulated with nonionic systems specifically for use with acrylic thickeners. Consequently there is a loss of viscosity; this can be quite pronounced although it depends on circumstances, particularly on the dye concentration. As already mentioned, this can be alleviated to some extent by copolymerization with acrylamide during manufacture. Otherwise it is necessary to try to eliminate all electrolytes from the system or to increase the concentration of thickener. Such measures have their limitations in practice, however. Alternative synthetic thickening agents include poly (vinyl alcohol) and copolymers of maleic anhydride with alkenes as shown,

A detailed comparative study of the rheological properties of four acrylic thickeners varying in relative molecular mass from 1.25 × 106 to 4 × 106 and of two cross linked ethylene-maleic anhydride copolymers. In respect of some properties, comparisons were also made with starch ether and an alginate.

Amongst other factors, the influence of molecular mass was demonstrated (Figure) showing that the higher the molecular mass of the acrylic polymer, the less the amount of thickener required to achieve a given viscosity. Nevertheless, earlier comments in relation to the stringiness of linear acrylic polymers should be borne in mind, i.e. factors other than viscosity need to be considered. Viscosity develops as water is absorbed; causing swelling and rearrangement of the polymer chains, a process that is assisted by, indeed is critically dependent on, neutralization.

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Textile Printing

Another common feature of said polymer is that of a considerable loss of their thickening activity in the presence of electrolytes. In order to overcome the problem of the contour sharpness, the printing pastes are formulated with additives which are generally hydro soluble polymers of different kind having low or relatively low molecular weight. Said additions however have a more or less negative influence on other printing characteristics and particular brightness, resistance to washings and softness of the printed textile in the pigment printing.

It is therefore evident that a thickener able to impart alone to the printing pastes a good contour sharpness involves a considerable improvement for the thickeners used in the textile printing. It is important that the absence of any electrolyte gives ideal printing. There should be taken great care in order to make printing paste and ensure that there is no electrolyte.An important example of synthetic thickeners is acrylic based thickeners.

4.9.2.3 Emulsion Thickeners:When immiscible liquids are emulsified the viscosity increases and this can be

exploited to prepare thickenings for textile printing. The emulsions used contain a hydrocarbon solvent(Usually white spirit), surfactant(s) and water; the oil phase must account for at least 70% of the total volume.

The first pigment printing systems introduced in the late 1930s were water-in-oil emulsions (that is, at least 70% of the product was water) in which typical surfactants were ethoxylated alcohols, acids or amides with a low degree of ethoxylation, perhaps 5–8 ox ethylene units per molecule, morph line/oleic acid or lauric, palmitic and stearic acid esters of sorbitol. Later, manufacturers developed oil-in-water emulsions for which appropriate surfactants are higher ethoxylated alcohols, acids or amides, or a wide variety of alkylaryl types. For any type of emulsion, the HLB of the emulsifying agent(s) is clearly of great importance.

The size of the droplets in an emulsion is inversely related to its viscosity, typical diameters ranging from 100 to 7000 nm. Theoretically no more than 75% of oil can be incorporated in an aqueous emulsion, assuming uniformly spherical droplets, but distortion due to packing allows significantly higher proportions of oil phase to be added. Presumably the oil droplets are stabilized by a surrounding layer of like charges, the type and strength of the charge depending on the surfactant(s) used. Consequently the stability of the emulsion tends to be impaired by any additions that reduce the charge on the droplets.

Emulsion thickeners can be mixed with low concentrations of either natural or synthetic thickeners, especially when applying fiber-substantive dyes rather than pigments; these additions act as film formers, taking the place of the binder used with pigments to increase retention of the dye by the substrate prior to fixation.Solubility of a thickener can be improved by

Controlled depolymerisation of a natural gum, into a low viscosity and reduced molecular weight product, which is more soluble.

By derivatization of a non-ionic gum into anionic polymer.

When the solubility of a thickener is more, it should also be easily washable.

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Textile Printing

Hence it can be concluded that their exist a wide range of natural and synthetic thickeners and we can select the most appropriate ones according to our requirements.

4.10 Ammonia:Viscosity depends upon the degree of ionization of carboxylic groups present in the

polymer chain. When NH4OH is added to polymer emulsion,4 (ammonium) counter ions and poly- some ionization occurs providing NH3 meric chains containing COO (carboxyl ate) ions. After complete neutralization is achieved, further addition of ammonia results in a build up of 4 counter ions, leading to a decrease in ionization of COOH groups NH 3 by the ECT of law of mass action and the common ion ECT. The extended chains start recoiling and viscosity decreases. Viscosity was found to increase with increasing pH up to 7.5–8, and beyond that the viscosity decreased.

Thickeners with improved filterability and good after-wash for printing

4.11 Urea: Urea is hygroscopic in nature. It absorbs water due to Hydrogen Bonding. During

curing, it releases water and provides wet conditions or water as media which is necessary for reaction between dye and fiber. 4.12 Printing Sampling Machine

We have applied the printing paste with pigment on the fabric on pigment sampling machine. This machine consists of 1 screen. In sampling machine there is only one screen used. The total no of screens used in a design are checked at sampling machine. We apply neudine GT an adhesive which fix the fabric on the fabric so that the surface becomes smooth which ultimately gives good printing. We applied all the recipes on the fabric on sampling machine in which magnetic rod squeegee system is used. In application of machine the rod rotates around its axis at a fix point with magnet and blanket also rotates around the machine. Half length of the blanket is below and half remains above while rotating. After printing when blanket reaches below the machine there is a system of washing of blanket. Machine specifications are illustrated below:

Model: 320/20/1 Manufacturer: Reggiani Manufacturing date: 2001 Speed of belt: 4 m/min Pressure of rod: 70 bar Rod diameter: 16mm Rod length: 3500mm Adhesive: Neudine GT Length of blanket: 21m Length of Machine: 10m

Drying & CuringThe fabric was dried at 110 °C and finally cured at 165 °C for 1-3 min.

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Textile Printing

4.13 Rotary screen printing:In the mid 1950s a new type of screen printing method involving a cylindrical screen

was developedRotary screen printing involves a series of revolving screens, each with revolving

screens, each with a stationary squeegee inside which forces the print paste onto the fabric. Twenty or more colors can be printed at the same time. As mush screen are used as much as colored are required in the design which is being printed. The process is much quicker and more efficient than flat screen printing. Since the 1970s it has grown to dominate the textile printing market.In Nishat Mill we discuses the Rotary machine of Reggiani (brand name).The figure is shown below.

ReggianiRenoir Futura, 180 Cm, Rotary Printing MachineBRAND Reggiani

REF. 119747-1

Model Renoir Futura

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Textile Printing

ww (in cm or inch) 180 Cm

Short description Rotary Printing Machine

YEAR 1988

QUANTITY 1

LOCATION EUROPE Western and Northern

DATE 25 Nov. 2009

Renoir Futura, 180 Cm, Rotary Printing Machine

Reggiani rotary printing machine Type Renoir futuraWorking width 1800 mm12 colorsSteam heated dryer. Year 1988.

Comprising of:- Testa non stop entry with cylinder bed and fabric conveyor belt.- Printing table equipped with 12 colorskalin suction unit for fabric cleaning and thermoplast.- Double passage dryer of 3 chamberssteam heating, exit by folder. - Equipped with squeegee washer and two screen washer.

4.13.1 Screen preparation:The nickel screens come in the mill in the form of rectangular packets in which the

screens are packed in rectangular form as shown in figure.

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Textile Printing

Screens

Screen specification

Screen material: Nickel Screen dimensions:

Sr. No. Dimension Size Unit

1. Length 1850, 2650, 3050, 3500 mm

2. Repeat (circumference) 640, 688, 820, 914 mm3. Thickness 100 μ m

Meshes: 60, 80, 100, 105, 125, 155.

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Textile Printing

Screen Meshes

Following are the main tasks performed in screen preparation:

• Rounding:• Coating:• Exposing:• Lightening:• Developing:• Curing:• End Ring:• Rechecking and Retouching:• Screen Stripping:

Rounding:Screens are first rounded in rounding section of screen making department. A metal

ring is placed at each side of the screen and the screen is heated at 240-260°C for 1 hour. This is the rounding temperature. After rounding, the screen is washed to remove dirt from it. Then it is dried at room temperature.

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Textile Printing

Coating:Once the screen is dried, it is coated with Photo sensitive material RS 100 Emulsion

and RS 101 Sensitizer. Required quantity of the sensitizer is 5%. These two chemicals are used in mixture. After coating the screen is kept for drying inside the dryer at 20-30°C for 15 to 20 minutes.

Machine name: Streric coating machine.Coating material: RS 100 Emulsions and RS 101 SensitizerColor of material: YellowExposing:

Ink Jet Model = CST-13303-02

After drying the screen is put on ink jet. Working of the machine is given below:

1. Very firstly, switch on the machine and the computer that is linked with the machine.2. Then goes to operating program and loading the files of the program.3. Now, the required screen with required meshes mounted on the machine.4. For airtight the screen we wound scotch tape on the both ends of the screens.5. Now according to the length of the screen the loaded program can run.

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Textile Printing

6. After completing the jetting process design no. and color no. is written on the one end of the screen.

7. Then remove the screen from the machine and ready for developing.Lightening: In this ink jet machine the phenomenon of lighting is done simultaneously with exposing, with 5000 watts light. The lightening head consists of a light that moves on the left and right side of the screen. These moves are called strokes. The number of strokes is fed in the machine. The finer the figure the lesser strokes are given to the screen. Developing:

Now rings are placed on each side of the screen once again and then the screen is immersed in water for 3-5 minutes in developing section. Because, ink is soluble in water and removed easily when washed with water with slight pressure. Then drying of the screen is done for 10-15 minutes. After developing the screen is checked on checking light stand fitted with tube lights in it.Curing:

It’s the process in which the screen is cured. The screens are placed vertically in the curing machine and maintained the temperature at 200-250°C, time given is 20 minutes for new prepared screens and 3o minutes for striped screens.

Curing Chamber.

End Ring:After curing screen is send to end ring section. In this section a head is put on each

side of the screen with the help of end ring machine, as shown in figures below

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Textile Printing

End ring machine End ring

Rechecking and Retouching: After end ring, the screen comes to rechecking and retouching section. In this

section extra pores other than the design are closed with the help of a chemical named SCR 52S Retouching Lacquer. When, screen is mounted on the tube light fitted stand.

Screen Stripping:After washing the screens with several chemicals screens are reused. This process is

called screen stripping. There is a specific recipe for stripping.

Recipe:

Sr. No. Chemical Amount Unit

1. Phenol 100 kg2. Formic acid 35 kg3. Methylene 10 kg4. Hydrochloric acid 30 kg

5. Water 825 kg

Total 1000 kg

The process mentioned above is rarely used today. SCI 31 stripper liquor is mostly used and is less harmful for consumers as compare to the old one.

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Textile Printing

Screen Engraving:The process of putting designs to be printed on rotary screen is known as screen

engraving. The most widely used process for screen engraving is known as the lacquer method. The overall process begins with the print design. Once the design is agreed upon, a textile artist separates the design into its individual colors. Each design component of each color is then made into a positive in black opaque ink on clear plastic film; the design is then reproduced color by color.

The rotary screen is evenly coated with a liquid water-soluble photosensitive resin. The screen is dried and stored in the dark. When ready for engraving, the coated screen is then covered in the exact required location with the opaque design positive. High intensity light is then directed onto the screen. Wherever the light hits the screen, it hardens the resin and forms a water insoluble barrier. Where light is prevented from hitting the screen due to the design positive, the resin remains water soluble. After the proper amount of light exposure time, determined by the choice of resin, the screen is washed and dried.

Methods of Engraving: Galvanic Engraving Laser Engraving1. Galvanic Engraving:

It is a technique for engraving screens using nickel electroplating technology to form the design on the screen. This technology is known as the galvanic method, but is now seldom used.

2. Laser Engraving:For rotary screens, the most modern method of screen making is known as laser

engraving. Here, the original design is digitized on a CAD system. At the same time, rotary screens are coated with resin, and the resin is completely hardened. The coated screen is then loaded on a mandrel, which is attached to a laser engraver. The machine engraves the screen using the digitized CAD print design data. Again only one color per screen is possible. The laser vaporizes the resin without damaging the screen material, which is normally nickel mesh for modern rotary screens. In Nishat 35 this method is used for engraving of screens.

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4.13.2 Squeegee systems:In rotary-screen printing, continuous rotation of a cylindrical screen while in contact

with the fabric ensures genuinely continuous printing. Print paste is fed into the inside of the screen, and during printing is forced out through the design areas with the aid of a stationary squeegee. Figure illustrates some of the squeegee types in use in ROTARY-SCREEN PRINTING

1. Conventional squeegee2. Airflow squeegee3. Magnetic Squeegee

If the squeegee pressure is uneven, the volume of print paste applied across the width will vary, resulting in an unlevel appearance in the final print. This problem is most serious when printing wide fabrics and special measures are used by some machine manufacturers to overcome it. For example, the Reggiani squeegee system consists of a phosphor bronze blade against which a rod is pressed by an inflated air sack, thus ensuring even pressure.

Mostly magnetic squeegee is used in rotary screen printing with the different diameters or size of the rods as: 8mm, 10mm, 12mm, 16mm, 20mm, and 24mm. These different sizes of rod are used according to the required design.

Arrangements of Rotary Screen Printing Machine: The batch of fabric for printing. Curved surface heating plate to heat the fabric before it pressed on to blanket, as

shown below:

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Textile Printing

Rotary printing machine

The rotary engraved screens belonging to the desired pattern are placed and fixed in their proper positions in a predetermined order. Although patterns with 12 colors are sometimes printed. Only 5 or 6 colored designs are usually most commonly used.

The printing paste is introduced in the centre of the rotary screen by means of the color pump and the color distribution system

The color paste is well distributed all over the interior of the rotary screen and is pressed onto the fabric by means of a well designed squeegee system.

Pumping action

The substrate, i.e., the cloth, travels over and along the endless printing conveyer blanket to the end of the printing table top.

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The printing process is completed at this stage, and the printed cloth is then led to the continuous dryer.

The dryer, having an adequate evaporation capacity is suitably designed. After drying the fabric is passed on the plaiting down arrangement.

Rotary printing Machine’s sketch

4.13.3 Special functions in Rotary printing:

Pumping of paste into the screen:The print paste is pumped into the screen through a flexible pipe from a container at

the side of the machine; inside the screen.The paste pipe has a rigid structure as it also acts as a support for the squeegee.

Holes in the pipe allow the paste to run down into the bottom of the screen; since the paste is pumped in from one end, the holes need to be larger at the end furthest from the pump to achieve an even spread across the full width of the screen.Sensor:

A sensor (level control) actuates the pump when the paste level falls below a preset height4.13.4 Gluing and washing devices:

Rotary-screen printing machines are equipped with gluing through. It has emery rollers which get the glue on itself from the through and applied on the endless blanket to provide

the adhesiveness for the fabric. The belt is washed in order to remove the residues of paste

and adhesive. Not only the belt, but also the screens and the paste input systems (hoses, pipes, pumps, squeegees, etc.) have to be cleaned up at each color change. Machine has 2 showers one up and one down with 2 scrapers respectively.

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Drying section:After printing the fabric, the paste is dried to prevent accidental smearing of the print

design and color migration. For this purpose the fabric is directed towards the drying section.Curing section:

The printed fabric may immediately go through the fixation process, or it may be held to go to fixation later. The type of colorant and production issues with the printing operation dictates the choice. This section of the machine has three chambers. The temperature is maintained in first chamber is 140°C, 160°C in second and in third there is also 160°C. This section also has 6 fans which blow the hot air towards fabric. After the curing in which the fixation is done the fabric is directed towards the trolley by plating mechanism.

Advantages: Higher production rate. Quick changeover of patterns Continuous patterns Continuous screen printing process Fabric glued to blanket Fabric moves under rotating screens Rod or blade squeegee system Fine adjustments easily made Speeds up to 120 yards per min.

Estimates indicate that this technique controls approximately, 65% of the printed fabric market worldwide.Disadvantages:

Design limitations Small repeats

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Experimental Work and Analysis

5 Pigment Printing Paste Recipe5.1 Thickener as a variable

Dye Red KGCBinder ET 50 g/kgThickener PTRV 15 g/kgUrea 25 g/kgAmmonia 12.5 g/kg

Recipe / 200 g

Auxiliaries QuantityBinder 10g/200gUrea 5g/200gThickener 3g/200gAmmonia 25g/200g

Thickener as a variableRecipe # 1

Auxiliaries QuantityDye 10gBinder 10g/200gUrea 5g/200gThickener 1g/200gAmmonia 2.5g/200g

Recipe # 2


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Recipe # 3


Recipe # 4


Recipe # 5


5.1.1 Testing “Thickener”Tear and Tensile Strength

SampleTensile Strength Tear Strength

Warp (N) Elong. % Weft (N) Elong. % Warp (N) Weft (N)1 693.2 12.23 552 8.52 6.64 7.792 722.9 12.99 550.7 828 7.06 8.223 678.6 12.96 506.7 7.62 7.64 7.064 708.3 12.96 529.7 8.14 7.64 7.065 701.1 13.27 475.1 7.23 7.06 8.22

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5.1.2 Rubbing Fastness

Sample Dry Rubbing Wet Rubbing1 3 32 3-4 1-23 3 1-24 3 1-25 3-4 1-2

Sample 1

Dry Wet

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Sample 2

Dry Wet

Sample 3

Dry Wet

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Sample 4

Dry Wet

Sample 5

Dry Wet

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5.1.3 Dry Cleaning Fastness

Sample Dry Cleaning Rating1 42 4-53 44 45 4

Sample 1

Dry Clean Original

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Sample 2

Dry Clean Original

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Sample 3

Dry Clean Original

Sample 4

Dry Clean Original

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Sample 5

Dry Clean Original

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5.1.4 Washing Fastness

Multi Fabric

Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Shade Change

Acetate 4-5 4-5 4-5 4-5 4-5

4Cotton 4-5 4 4-5 4-5 4-5Nylon 4-5 4-5 4-5 4-5 4-5Polyester 4-5 4-5 4-5 4-5 4-5Acrylic 4-5 4-5 4-5 4-5 4-5wool 4-5 4-5 4-5 4-5 4-5

Sample 1

Multi Fabric Wash Sample Original Sample

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Sample 2

Multi fabric Wash Sample Original Sample

Sample 3


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Sample 4


Sample 5


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5.2 Binder as a variableRecipeDye 10gUrea 25gThickener 15g/kgBinder 50g/kgAmmonia 12.5g/kg

Recipe # 1Auxiliaries QuantityBinder 6g/200gUrea 5g/200gThickener 3g/200gAmmonia 2.5g/200g

Recipe # 2

Auxiliaries QuantityBinder 8g/200gUrea 5g/200gThickener 3g/200gAmmonia 2.5g/200g

Recipe # 3


Recipe # 4


Recipe # 5


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5.2.1 Testing “Binder” Tear and Tensile


Warp (N) Elong. % Weft (N) Elong. % Warp (N) Weft (N)1 715.02 13.05 569.4 8.48 8.22 9.362 720.32 13.18 532.1 828 7.06 8.223 730.22 12.96 506.7 7.62 7.64 7.064 732.3 12.96 502.31 8.14 8.25 7.065 735.24 13.27 475.1 7.23 8.40 8.22

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5.2.2 Rubbing Fastness for Binder

Sample Dry Rubbing Wet Rubbing1 2-3 1-22 3 1-23 3 1-24 3-4 1-25 3-4 2-3

Sample 1

Dry Wet

Sample 2

Dry Wet

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Sample 3

Dry Wet

Sample 4

Dry Wet

Sample 5

Dry Wet

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5.2.3 Dry cleaning Fastness

Sample Dry Cleaning Rating1 32 23 34 35 2

Sample 1

Dry Clean Sample Original Sample

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Sample 2 Dry Clean Sample Original Sample


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Multi Fabric

Sample 1 Sample 2 Sample 3 Sample 4 Sample 5

Acetate 4-5 4-5 4-5 4-5 4-5Cotton 4-5 4 4 4-5 4Nylon 4 4 4 4 4-5

Polyester 4-5 4 4 4 3-4Acrylic 4-5 4 4 4 4Wool 4-5 4-5 4 4-5 3-4Shade

Change4 4 4-5 4-5 4

Sample 1


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Sample 2


Sample 3 Multi Fabric Wash Sample Original Sample

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Sample 4


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Sample 5 Multi Fabric Wash Sample Original Sample

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5.3 Ammonia (NH3) as a variableRecipeDye 10gUrea 25gThickener 15g/kgBinder 50g/kgAmmonia 12.5g/kg

Recipe/ 200 gDye 10g (Red KGC)Binder ET 5gUrea 5 gThickener PTRV 3 gAmmonia 2.5g

Recipe # 1

Auxiliaries QuantityBinder 6gUrea 5gThickener 3gAmmonia 1.7g

Recipe # 2


Recipe # 3


Recipe # 4


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Recipe # 5Auxiliaries QuantityBinder 6gUrea 5gThickener 3gAmmonia 3.3g

5.3.1 Testing (NH3) Tear & Tensile

Tear and Tensile


Warp (N) Elong. % Weft (N) Elong. % Warp (N) Weft (N)1 685.5 12.89 549.5 7.96 7.64 9.362 834.4 13.10 545.5 8.24 7.79 8.223 724 13.19 547.9 8.51 7.64 8.794 713 13.16 558.9 8.62 7.64 8.795 737.6 13.26 532.1 8.28 8.22 8.22

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Sample Dry Rubbing Wet Rubbing1 3-4 2-32 3-4 1-23 3 1-24 3-4 1-25 4 1-2

Sample 1

Dry Wet

Sample 2

Dry Wet

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Sample 3

Dry Wet

Sample 4

Dry Wet

Sample 5

Dry Wet

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5.3.3 Dry cleaning Fastness

Sample Dry Cleaning Rating1 3-42 43 44 45 4

Sample 1

Dry clean Original

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Sample 2

Dry clean Original

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Sample 3

Dry clean Original

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Sample 4

Dry clean Original

Sample 5

Dry clean Original

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Multi Fabric


Acetate 3 3-4 4 4 4Cotton 3 3-4 4 4 4Nylon 3 3-4 4 4 4Polyester 3 3-4 4 4 4Acrylic 3 3-4 4 4 4wool 3 3-4 4 4 4Shade Change

4-5 4-5 4-5 4-5 4-5

Sample 1


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Sample 2


Sample 3


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Sample 4


Sample 5


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5.4 Urea as a variableRecipeDye 10g (Red KGC)Binder ET 25 g/kgUrea 15 g/kgThickener PTRV 50 g/kgAmmonia 12.5 g/kg

Recipe /200g

Binder 6g Urea 25gThickener 3g

Ammonia 2.5g

Recipe # 1


Recipe # 2


Recipe # 3


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Recipe # 4


Recipe # 5


5.4.1 Testing “Urea” Tear & Tensile

Tear and Tensile


Warp (N) Elong. % Weft (N) Elong. % Warp (N) Weft (N)1 715.8 12.38 512.4 8.52 7.06 8.792 696.5 12.93 521.4 8.13 7.06 8.223 741.5 12.93 546.2 8.31 7.64 8.224 690.7 12.03 516 8.22 8.22 8.225 716 12.35 499.1 8.12 8.22 8.79

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Sample Dry Rubbing Wet Rubbing1 3-4 1-22 3-4 1-23 3 1-24 2-3 1-25 4 1-2

Sample 1

Dry Wet

Sample 2

Dry Wet

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Sample 3

Dry Wet

Sample 4

Dry Wet

Sample 5

Dry Wet

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5.4.3 Dry Cleaning Fastness

Sample Dry Cleaning Rating1 3-42 3-43 3-44 3-45 3-4

Sample 1

Dry Clean Original

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Sample 2

Dry Clean Original

Sample 3

Dry Clean Original

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Sample 4

Dry Clean Original

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Sample 5

Dry Clean Original

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Multi Fabric


Acetate 4 4 4-5 4-5 4-5Cotton 4 4 4-5 4-5 4-5Nylon 4 4 4-5 4-5 4-5Polyester 4 4 4-5 4-5 4-5Acrylic 4 4 4-5 4-5 4-5wool 4 4 4-5 4-5 4-5Shade Change

4-5 4-5 4-5 4 4-5

Sample 1


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Sample 2


Sample 3


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Sample 4


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Sample 5


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Testing Methods and Procedures

6 What is color fastness?The resistance of a material to change in any of its color characteristics, to transfer of

its colorants to adjacent materials or both, as a result of the exposure of the material to any environment that might be encountered during the processing, testing, storage or use of the material.

6.1 Rubbing FastnessA transfer of colorant from the surface of a colored yarn or fabric to another surface

or to an adjacent area of the same fabric principally by rubbing.Test Standard

The test standard used is AATCC.Procedure

We fasten each test specimen by means of clamps to the baseboard of the testing device so that the long direction of the specimen follows the track of the device. Test the specimen prepared according to the procedures dry or wet. While testing multi colored textile care should be taken to position the specimen such a way that all colors of the design are rubbed in the test. Alternatively, if the areas of color are sufficiently large, more test specimens may be taken and individual colors assessed separately. It is necessary to eliminate dyed fibers pulled out during rubbing consider only the coloration due to staining by the dyestuff.6.1.1 Dry Rubbing

With the dry rubbing cloth flat in place over the end of the finger of the testing device , rub to and fro in a straight line along a track10cm long on the dry specimen,10 time to and fro in 10 sec, with a downward force of 9 N. we tested the fabric dry and wet both.6.1.2 Wet Rubbing

We adopted the same process as in case of dry rubbing but the difference is only that we drop water on the rubbing specimen to ensure 100% pick up. After rubbing dry the cloth at room temperature. After testing we assessed the staining of the cotton rubbing cloths (dry and wet) with grey scale. Gray Scale

The scale consisting of pairs of standard gray chips, the pairs representing progressive differences in color or contrast corresponding to numerical color fastness grades

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6.2 Washing FastnessTest Standard: Iso-105-co3Specimen size: 10 × 4 cmChemicals Used:

Detergent W.OPB 5g/l (W.OPB) Sodium Carbonate 2g/l

ProcedureA sample of 10 × 4 cm is attached with a multi fabric which has six different types

of fabric like acetate, cotton, nylon, polyester, acrylic and wool. The sample with multi fabric is treated in a steel glass with a solution of detergent and sodium carbonate with 150 ml volume of liquor. The glass is fitted in a machine called gyro wash. Glass rotates at 4 rpm in the machine which is half filled with water at a temperature of 60 °C for 30 min. After that the fabric is washed with normal water and then dried.

The wash out property of the sample is determined by assessing the stains on different fabrics of the multi fabric and also we check out the change of shade in washed sample to original sample.

6.3 Dry Cleaning Fastness

Test Standard: Iso-105-Do1Specimen size: 10 × 4 cmChemical Used: Perchloroethylene

The loss of color during dry cleaning is referred to as a lack of dry cleaning fastness. Color loss will occur during dry cleaning if dyes have been used which are held loosely by the fiber and which are soluble in a dry cleaning solvent used. In general, the loss of color during dry cleaning is rare.

Under the usual dry cleaning conditions, one finds in the home, there are few chemicals (such as acids and chlorine containing chemicals) that have effect on the covalent bond that exists between the reactive dye molecule and the cellulosic fiber polymer. Thus,

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the dry cleaning fastness of textiles colored with reactive dye depends on the dry cleaning conditions.

ProcedureWe prepared a bag with inside dimensions of 10×10 cm using the un dyed cotton twill cloth by sewing together two squares of this cloth around three sides. Placed the specimen and 12 steel discs inside the bag. Close the bag sewing it. Placed the bag containing the specimen and steel disc in the container in 200 ml of Perchloroethylene at 60°c for 30 minutes. In the Gyro wash machine. Moved the bag from the container withdraw the specimen, placed it between absorbent paper or cloth and squeeze or centrifuge to remove surplus solvent. Dry the specimen by hanging it in the air at the temperature of 30°c. Assess the change in the color of specimen with grey scale for assessing change in color.

Twill quality fabric for dry Cleaning

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Gyro wash for Washing and Dry Cleaning Machine

6.4 Tear Strength TestingStandard: ISO13937-1Sample Size: 63 × 100mmCut Length: 2cm

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Elmendorf Tear Strength TesterThe ELM Series Elmendorf Tearing Testers are accurate, low-cost and high quality falling pendulum tear testing Instruments with analog display for determination of the average force required to propagate a single-rip tongue-type tear starting from a cut in paper, cardboard, plastics, non-woven and woven fabrics, with proper configuration.

6.4.1 Single Rip MethodThe average force required to propagate tearing through a specified length of plastic

film or no rigid sheeting on an Elmendorf-type tear tester.

Rectangular SpecimenThe Elmendorf pendulum type ballistic tester which measures energy loss during

tearing. The tearing force is related to the energy loss by the following equationEnergy Loss = Tearing Force × Distance

The apparatus is consists of a sector shaped pendulum carrying a clamp which is in alignment with a fixed clamp when the pendulum is in the raised starting position where it has maximum potential energy. The specimen is fastened between the two clamps and the

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tear is started by a slit cut in the specimen. The pendulum is then released and the specimen is torn as the moving jaw moves away from the fixed one. A digital meter attached to the pendulum van be graduated to read the tear force directly.

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Discussion & Conclusion

7 Printing Paste

The pigment printing paste was consisted of the following constituents

1. Red KGC2. Binder ET3. Thickener Ptrv4. Liq. Ammonia5. Urea

The standard recipe is composed of the following quantities

Dye Red KGCBinder ET 50 g/kgUrea 25 g/kgThickener PTRV 15 g/kgAmmonia 12.5 g/kg

This recipe was of 1 kg we made recipe of 200gThat is as follows

Dye 10gBinder ET 10 g/200gUrea 5 g/200gThickener PTRV 3g/200gAmmonia 2.5g/200g

We have taken this recipe as a standard and worked on its optimization. We have taken each constituent five different values and according to them we checked their rubbing fastness, washing Fastness, dry cleaning fastness, tear strength and tensile strength.We changed the quantities of any one constituent while keeping other constituents values constant.

Thickener as a variableAs we know that the working of thickener is thickened, to the printing paste and also

provide uniform consistency to the printing paste. That in turns makes the paste viscous and sticky with uniform viscosity.

We observed from the recipe variation of the thickener that with the increase in its quantity on small scale enhance the washing, rubbing and dry cleaning fastness of fabric

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towards color. But this phenomenon has not prominent effect on the tear and tensile strength of the fabric,

We have got better result for the thickener quantity in the fourth recipe, 4g per 200 g paste proved to be the best figure. Because, the minimum requirement of the viscosity for paste is 12000 cps. If the viscosity is recorded below this quantity the paste is not as thickened as required and during application on the fabric the paste will penetrate in the fabric which gives the main disadvantage of color bleeding.

On the other hand if we add the more quantity on after a specific limit it make the paste more thickened. Then the paste is difficult to pass from the screen and it also gives destructed effects on the fabric surface as brittleness, cracks and also enhances the cost of the paste.

Binder as a variableThe quantity of the binder is directly linked with the washing, rubbing, dry cleaning

fastness and strength properties of fabric. According to our working on recipe evaluation, we observed that due to the increasing the quantity of binder in the paste with other constituents remaining constant the value of washing, rubbing, dry cleaning fastness and strength properties increased.

The increasing quantity of the binder provides continuously the favorable conditions for bonding of the binder with both fiber and colorant. In case, of binder we take five different quantities of binder with the regular interval of digits. On the consideration of our working the recipe number three proved to best one in which we used 10g per 200 g paste than the other four. Because it highly, satisfied all the washing, rubbing, dry cleaning fastness and strength properties. When we got the required result of each property on any quantity we must not add any more binder because it makes us cost unconscious.

Ammonia as a variableAmmonia swells the printing paste and in curing it evaporates leaving behind the

acidic Media. This acidic media provides the favorable condition for the binder to make cross link. The increased quantity of the Ammonia will make paste thick which will make the paste difficult to pass through the screen. In our working the recipe 5 in which it is used 3.3g for 200 g paste proved to be the best one giving optimized result of color and strength properties.

Urea as a variableUrea is hygroscopic in nature. It absorbs water due to Hydrogen Bonding. During

curing, it releases water and provides wet conditions or water as media which is necessary for reaction between dye and fiber. Urea makes the fixation of the pigment efficient. By varying the quantities of the urea we find out that the recipe three in which it is used 5g per 200g.

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8 ConclusionThe optimized recipe of the pigment printing is as Urea 5g/200g

Binder 10g/200gThickener 4g/200g

Ammonia 3.3g/200gThe optimized recipe gives the required result of the Rubbing fastness, Washing fastness, Dry cleaning fastness, Tear strength and Tensile strength. The quantity of binder is that which gives good cross linking and making the pigment resistant to rubbing, washing fastness and tear tensile strength. this required cross linking of binder with pigment and fiber is achieved by the required quantity of ammonia which provides the favorable conditions to the binder to make bonding. The quantity of thickener also proves to be the best one according to paste viscosity. This quantity gives us the optimized viscosity of paste making it uniform and even. The quantity of urea also proves to be the best one because it provides such moisture inn curing which makes the binder to do efficient cross linking and increasing effectiveness of the pigment life against the washing dry cleaning agents and also strength of the fabric.

Tear and Tensile strength

Tensile strength(N) Tear strength(n)warp weft warp weft735 550.56 7.60 8.25

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Rubbing Fastness

Dry Wet 3-4 2-3

Dry Wet

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Washing Fastness

Multi. Fabric Staining Change of shadeAcetate 4-5 4Cotton 4 4Nylon 4-5 4

Polyester 4-5 4Acrylic 4 4

wool 4-5 4

Multi Fabric Wash Original

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Dry Cleaning Fastness

Sample Dry clean Rating

1 4

Dry Clean Original

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