Natural Rubber Latex PSA's do they perform ?

FEB 2017FEB 2017

Natural RubberNatural RubberLatex basedLatex basedPressure SensitivePressure SensitiveAdhesivesAdhesives

Natural RubberNatural RubberLatex basedLatex basedPressure SensitivePressure SensitiveAdhesivesAdhesives

Water Borne Pressure Sensitive Adhesives

A latest review on Natural Rubber Latex based PressureSensitive Adhesives , in comparison with the , Water BorneAcrylic Adhesives , and Solvent Based , Acrylics or Rubber.

I hope we all will agree on that , there is a general mentalblock in Technocrats mindCan water borne offer the same properties ,like adhesion, waterresistance and heat resistance ,as solvent borne PSA’s

2/20/2017 2

Water Borne Pressure Sensitive Adhesives

A latest review on Natural Rubber Latex based PressureSensitive Adhesives , in comparison with the , Water BorneAcrylic Adhesives , and Solvent Based , Acrylics or Rubber.

I hope we all will agree on that , there is a general mentalblock in Technocrats mindCan water borne offer the same properties ,like adhesion, waterresistance and heat resistance ,as solvent borne PSA’s

Can the water borne PSA’s overcome themechanical stability problems commonlyseen in water borne Acrylic Adhesives ?

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Can the water borne PSA’s overcome themechanical stability problems commonlyseen in water borne Acrylic Adhesives ?

The purpose of publishing this Article is tostudy the behavior and also to compare theperformance ofLatex Borne Rubber PSA , withRubber / Acrylic Solvent BorneAs well as Water Borne Acrylic.

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The purpose of publishing this Article is tostudy the behavior and also to compare theperformance ofLatex Borne Rubber PSA , withRubber / Acrylic Solvent BorneAs well as Water Borne Acrylic.

Let me address to a general question in any bodies mindLet me address to a general question in any bodies mind

Water Borne Adhesives And Coatings

Natural Rubber Latex based adhesives , can they offer the same ,amount of Adhesion, water resistance ,Heat Resistance, holdingpower , and service life ?can they overcome The Mechanical Stability Problems ?

Can they replace Solvent Borne PSA ?

The answer is YesYes2/20/2017 5

Let me address to a general question in any bodies mindLet me address to a general question in any bodies mind

Water Borne Adhesives And Coatings

Natural Rubber Latex based adhesives , can they offer the same ,amount of Adhesion, water resistance ,Heat Resistance, holdingpower , and service life ?can they overcome The Mechanical Stability Problems ?

Can they replace Solvent Borne PSA ?

The answer is YesYes

Let us know studyLet us know study

What is Pressure Sensitive Adhesive ? and how many differentvarieties are available ? How do we classify them ?

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Let us know studyLet us know study

What is Pressure Sensitive Adhesive ? and how many differentvarieties are available ? How do we classify them ?

Pressure-Sensitive Adhesive is adhesive which forms a bondwhen pressure is applied to marry the adhesive with theadherent. No solvent, water, or heat is needed to activate theadhesive. It is used in pressure-sensitive tapes, labels, gluedots, note pads, automobile trim, and a wide variety of otherproducts.As the name "pressure-sensitive" indicates, the degree ofbond is influenced by the amount of pressure which is used toapply the adhesive to the surface.Surface factors such as smoothness, surface energy, removalof contaminants, etc. are also important to proper bonding.

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Pressure-Sensitive Adhesive is adhesive which forms a bondwhen pressure is applied to marry the adhesive with theadherent. No solvent, water, or heat is needed to activate theadhesive. It is used in pressure-sensitive tapes, labels, gluedots, note pads, automobile trim, and a wide variety of otherproducts.As the name "pressure-sensitive" indicates, the degree ofbond is influenced by the amount of pressure which is used toapply the adhesive to the surface.Surface factors such as smoothness, surface energy, removalof contaminants, etc. are also important to proper bonding.

PSAs are usually designed to form a bond and hold properlyat room temperatures. PSAs typically reduce or lose theirtack at low temperatures and reduce their shear holdingability at high temperatures; special adhesives are made tofunction at high or low temperatures. It is important tochoose an adhesive formulation which is designed for itsintended use conditions.

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PSAs are usually designed to form a bond and hold properlyat room temperatures. PSAs typically reduce or lose theirtack at low temperatures and reduce their shear holdingability at high temperatures; special adhesives are made tofunction at high or low temperatures. It is important tochoose an adhesive formulation which is designed for itsintended use conditions.

Pressure-sensitive adhesives are designed for either permanent orremovable applications. Examples of permanent applicationsinclude safety labels for power equipment, foil tape for HVACduct work, automotive interior trim assembly, and sound/vibrationdamping films. Some high performance permanent PSAs exhibithigh adhesion values and can support kilograms of weight persquare centimeter of contact area, even at elevated temperature.Permanent PSAs may be initially removable (for example torecover mislabeled goods) and build adhesion to a permanentbond after several hours or days.

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Pressure-sensitive adhesives are designed for either permanent orremovable applications. Examples of permanent applicationsinclude safety labels for power equipment, foil tape for HVACduct work, automotive interior trim assembly, and sound/vibrationdamping films. Some high performance permanent PSAs exhibithigh adhesion values and can support kilograms of weight persquare centimeter of contact area, even at elevated temperature.Permanent PSAs may be initially removable (for example torecover mislabeled goods) and build adhesion to a permanentbond after several hours or days.

Removable adhesives are designed to form a temporary bond,and ideally can be removed after months or years withoutleaving residue on the adherent. Removable adhesives are usedin applications such as surface protection films, masking tapes,bookmark and note papers, price marking labels, promotionalgraphics materials, and for skin contact (wound care dressings,EKG electrodes, athletic tape, analgesic and transdermal drugpatches, etc.). Some removable adhesives are designed torepeatedly stick and un stick. They have low adhesion andgenerally cannot support much weight.

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Removable adhesives are designed to form a temporary bond,and ideally can be removed after months or years withoutleaving residue on the adherent. Removable adhesives are usedin applications such as surface protection films, masking tapes,bookmark and note papers, price marking labels, promotionalgraphics materials, and for skin contact (wound care dressings,EKG electrodes, athletic tape, analgesic and transdermal drugpatches, etc.). Some removable adhesives are designed torepeatedly stick and un stick. They have low adhesion andgenerally cannot support much weight.

Types of Pressure Sensitive Adhesives

In General , there are many types of PSA’s are available and wecan classify them as below.

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EmulsionEmulsions are generally Acrylic Polymerbased adhesives that are suspended in water

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SolutionThese are Solvent Adhesives , based onAcrylics , Rubber , dissolvedin Petroleum based solvents

Hot MeltAre generally based on Block Co Polymers of ,Styrene Isoprene Styreneor Styrene Butadiene Styrene

Ultra violetThese are Ultra Violet light cured Adhesives ,based on Acrylics

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Ultra violetThese are Ultra Violet light cured Adhesives ,based on Acrylics

100% SolidThese adhesives are generally based onSilicones , Polyurethanes ,that do not contain any Solvent

The Pressure Sensitive Adhesives can be furthercategorized based on Chemical Composition

PSA

EMULSION SOLVENT HOTMELT

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RUBBERRUBBER ACRYLICACRYLIC RUBBERRUBBER ACRYLICACRYLIC RUBBER

FURTHER VARIATION

PERMANENT

REMOVE ABLE

FURTHER VARIATION

PERMANENT

REMOVE ABLE

FURTHER VARIATION

PERMANENT

REMOVE ABLE

The Pressure Sensitive Adhesives can be furthercategorized like

PSA

Rubber Base

Acrylic Base

Emulsion/ LatexEmulsion/ Latex

Dry Rubber Base

Emulsion /WB Base

Solvent Base

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PSA

100% Base

Hotmelt Base

UV Base

Solvent Base

Copolymer Base

EVA/Acrylic/PU/APO Base

Si/Acrylic Solventless

Silicone Base


Natural Rubber Molecule

PSA

Rubber Base

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Emulsion/ LatexEmulsion/ Latex

Dry Rubber Base


PSA

Acrylic Base

Emulsion /WB Base

Solvent Base

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PSA

Hotmelt Base

Copolymer Base

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EVA/Acrylic/PU/APO Base


PSA

UV Base

Si/Acrylic Solventless

We will notWe will notdiscuss morediscuss moreabout theseabout theseAdhesives in thisAdhesives in thispresentation ,presentation ,since our focus issince our focus ison Nat Rubberon Nat RubberLatex BasedLatex BasedAdhesivesAdhesives

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100% Base Silicone Base



PSA

100% Base

Silicone Base


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What Is The Difference Between Solvent And Water BasedWhat Is The Difference Between Solvent And Water BasedAcrylic Adhesives?Acrylic Adhesives?

water based and solvent based. There is no indication that a wateror solvent based provides a better bond to film. Water or solventadhesives are the carriers for the solids in the coating process andare removed during the curing process.Water based adhesives produce less emission when cured and aregenerally faster to run when coating. Solvent based adhesives runslower when coating due to the time it takes to cure, making themgenerally more expensive. There is often a stigma attached to waterbased adhesives, but over time their construction and performancehas greatly improved.The performance of a film (shrink, aging, sheer, peel) isformula dependent, not technology dependent (water based vs.acrylic based).2/20/2017 21


water based and solvent based. There is no indication that a wateror solvent based provides a better bond to film. Water or solventadhesives are the carriers for the solids in the coating process andare removed during the curing process.Water based adhesives produce less emission when cured and aregenerally faster to run when coating. Solvent based adhesives runslower when coating due to the time it takes to cure, making themgenerally more expensive. There is often a stigma attached to waterbased adhesives, but over time their construction and performancehas greatly improved.The performance of a film (shrink, aging, sheer, peel) isformula dependent, not technology dependent (water based vs.acrylic based).


There is not a general statement that says water based adhesive isbetter than acrylic based adhesive or vice versa. To determine aperformance difference you would need to compare a particularconstruction of water based adhesive to a particular construction ofsolvent based adhesive in a given application.The most important aspect of an adhesive, are its physical propertiesdesigned for the intended application and is it consistent in coatingand quality?Solvent based adhesives may provide greater performance over thelife of the film. Water based adhesives may show lower resistance toshrink, aging, sheer and peel, but this usually occurs towards theend of their designed life.

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There is not a general statement that says water based adhesive isbetter than acrylic based adhesive or vice versa. To determine aperformance difference you would need to compare a particularconstruction of water based adhesive to a particular construction ofsolvent based adhesive in a given application.The most important aspect of an adhesive, are its physical propertiesdesigned for the intended application and is it consistent in coatingand quality?Solvent based adhesives may provide greater performance over thelife of the film. Water based adhesives may show lower resistance toshrink, aging, sheer and peel, but this usually occurs towards theend of their designed life.

PSA

RUBBERRUBBER

EMULSION

Now let us go back to

We willdiscuss aboutLatex BasedPSA’s indetails after awhile

WB PSA’s Acrylic based dominatethe market at the moment.Formulated as Emulsions of Acrylicpolymers in water.Surfactants are used to stabilize theHydrophobic polymers.More details on next page

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We willdiscuss aboutLatex BasedPSA’s indetails after awhile

WB PSA’s Acrylic based dominatethe market at the moment.Formulated as Emulsions of Acrylicpolymers in water.Surfactants are used to stabilize theHydrophobic polymers.More details on next page

RUBBER Vs ACRYLIC ADHESIVERUBBER Vs ACRYLIC ADHESIVE

To manufacture Nat RubberAdhesives, rubber ismasticated and a variety oftackifying resins , and otheringredients are mixed tomake it tacky .These Ingredients do notchange, they are simplymixed together to produce anadhesive.

To manufacture acrylicadhesives, plastic polymers aresynthesized to obtain specificchemical structures that are tacky.Acryclics can be formulated toproduce specific performancecharacteristics.

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To manufacture Nat RubberAdhesives, rubber ismasticated and a variety oftackifying resins , and otheringredients are mixed tomake it tacky .These Ingredients do notchange, they are simplymixed together to produce anadhesive.

To manufacture acrylicadhesives, plastic polymers aresynthesized to obtain specificchemical structures that are tacky.Acryclics can be formulated toproduce specific performancecharacteristics.


This means rubber adhesiveshave: high initial adhesion some adhesionbuildup good shear strength moderate temperatureresistance good solventresistance fair UV resistance moderate durability

This means acrylic adhesiveshave: fair initial adhesion gradual adhesion buildup high shear strength high temperatureresistance excellent solventresistance excellent UV resistance excellent durability

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This means rubber adhesiveshave: high initial adhesion some adhesionbuildup good shear strength moderate temperatureresistance good solventresistance fair UV resistance moderate durability

This means acrylic adhesiveshave: fair initial adhesion gradual adhesion buildup high shear strength high temperatureresistance excellent solventresistance excellent UV resistance excellent durability


Where do you find Rubberadhesives –most masking tapes (paper), mostpackaging tapes (plastics),vinyl and plastic backing.

This category of solutions are bestwhen you want quick adhesion andthe maximum holding power in theshortest amount of time.Consider Double Coated tapeswhen you need quick bond to paperand paper board,ormost fiber based products.

Where do find Acrylic adhesive:

On backings made of Polyester, Foils,Teflons, Tedlar, Kaptons, andother Polypropylene single side tapes.Best to use when you want long ternholding, high temperature, and extremeexposure to conditions.Consider Double Coated tapes when youneed high holding power and adhesionto a wide variety of substrate surfaces.

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Where do you find Rubberadhesives –most masking tapes (paper), mostpackaging tapes (plastics),vinyl and plastic backing.

This category of solutions are bestwhen you want quick adhesion andthe maximum holding power in theshortest amount of time.Consider Double Coated tapeswhen you need quick bond to paperand paper board,ormost fiber based products.

Where do find Acrylic adhesive:

On backings made of Polyester, Foils,Teflons, Tedlar, Kaptons, andother Polypropylene single side tapes.Best to use when you want long ternholding, high temperature, and extremeexposure to conditions.Consider Double Coated tapes when youneed high holding power and adhesionto a wide variety of substrate surfaces.

When these adhesives are driedThe surfactants segregate to inter particle domainsSurfactant rich domains strongly interact with water , that leadto dramatic differences between wet and dry mechanicalproperties of adhesive film.

The composition and structure of these materials allow them toreadily interact with moisture .

The adhesive dry film can contain moisture due to the presenceof surfactants . The moisture plasticizes the adhesive film andreduces its cohesive strength and enhances the flow properties.

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When these adhesives are driedThe surfactants segregate to inter particle domainsSurfactant rich domains strongly interact with water , that leadto dramatic differences between wet and dry mechanicalproperties of adhesive film.

The composition and structure of these materials allow them toreadily interact with moisture .

The adhesive dry film can contain moisture due to the presenceof surfactants . The moisture plasticizes the adhesive film andreduces its cohesive strength and enhances the flow properties.

WB Acrylic PSA’s are composed of Vinyl Acrylic MonomersA variety of monomers are used to achieve desired properties such asTack, Peel and ShearA most important property to catagories monomers is the GlassTransition Temp ( Tg ) .This property ( Tg) divides the monomers into

Soft Tg about -30 deg C

Medium

Hard Tg about + 30 deg Cand

Functional

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WB Acrylic PSA’s are composed of Vinyl Acrylic MonomersA variety of monomers are used to achieve desired properties such asTack, Peel and ShearA most important property to catagories monomers is the GlassTransition Temp ( Tg ) .This property ( Tg) divides the monomers into

Soft Tg about -30 deg C

Medium

Hard Tg about + 30 deg Cand

Functional

Commonly Used Monomers for the manufacture of EBPSA’s

SOFT MONOMERS HARD MONOMERS

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FUNCTIONALMONOMERS

MEDIUM MONOMERS

The handling of WB Acrylic PSA as a Hydrophobic colloidal provides manyadvantages , like ease of handling coating etcButSurfactant additives consist molecules having a polar water-soluble groupattached to a water-insoluble hydrocarbon chain, tend to create a potentialproblem

These molecules are retained in the adhesive and they are likely to migrateinto adjacent layerThey influence the rapid uptake of moistureThey have a impact on the properties of the adhesive film

In the next slide you can see the impact of these molecules on the adhesivefilm .Under low humidity level of 3%And High Humidity level of 90%

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The handling of WB Acrylic PSA as a Hydrophobic colloidal provides manyadvantages , like ease of handling coating etcButSurfactant additives consist molecules having a polar water-soluble groupattached to a water-insoluble hydrocarbon chain, tend to create a potentialproblem

These molecules are retained in the adhesive and they are likely to migrateinto adjacent layerThey influence the rapid uptake of moistureThey have a impact on the properties of the adhesive film

In the next slide you can see the impact of these molecules on the adhesivefilm .Under low humidity level of 3%And High Humidity level of 90%

a) Atomic Force Microcopy (AFM) of a WB PSA filmb) the particle size distribution for adhesive in emulsionform

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AFM images for the Adhesive filmc) at 3% relative Humidityandd) at 90% relative Humidity

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Impact of Moisture on Behavior and Property ofWB Acrylic PSA’s

The presence ofSurfactantsAndthe presence ofrepeated units ofacrylic acid andvinyl acetate

tendto absorbwater

Andmodify thestiffnessandstrength

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The presence ofSurfactantsAndthe presence ofrepeated units ofacrylic acid andvinyl acetate

tendto absorbwater

Andmodify thestiffnessandstrength

Cohesive Strength of Adhesive andTack

Here twoPropertiesare reallyimportant

TheThewettingwetting

And

thethestrengthstrengthto holdto hold

As amatter offactThesetwopropertiesareexactlytheoppositeof eachother

The adhesive tends to flow at lowpressure to wet a surfaceIncrease in the adhesive ability toflow/ wet

IsAccompaniedBy

Reduction in strength

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Here twoPropertiesare reallyimportant

TheThewettingwetting

And

thethestrengthstrengthto holdto hold

As amatter offactThesetwopropertiesareexactlytheoppositeof eachother

The adhesive tends to flow at lowpressure to wet a surfaceIncrease in the adhesive ability toflow/ wet

IsAccompaniedBy

Reduction in strength

TheThe PSAPSA properties are gauged by performance testingproperties are gauged by performance testing

Thesegenerallyinclude

TackTack

Peel

And

shearshear

TackTackIs a measurement of ability of the adhesive to rapidly wet thesurface and form a bond. So Tack is the force/energy requiredto separate two surfaces brought together at low pressure. Tackis also referred to as the Aggressiveness of the adhesive

ShearShearThis involves a constant shear on the test piece area . AThis involves a constant shear on the test piece area . Aconstant weight is hung on to the tape backing with adhesiveconstant weight is hung on to the tape backing with adhesiveside bonded to a SS plate. Eventually the constant weight isside bonded to a SS plate. Eventually the constant weight isresponsible for the adhesive tape to slip down from the SSresponsible for the adhesive tape to slip down from the SSplate . This happen due to a split of the adhesive layer. It’splate . This happen due to a split of the adhesive layer. It’scalled as cohesive failure. Hence Shear test is a gauge ofcalled as cohesive failure. Hence Shear test is a gauge ofCohesive strength of the adhesiveCohesive strength of the adhesive

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Thesegenerallyinclude

TackTack

Peel

And

shearshear

ShearShearThis involves a constant shear on the test piece area . AThis involves a constant shear on the test piece area . Aconstant weight is hung on to the tape backing with adhesiveconstant weight is hung on to the tape backing with adhesiveside bonded to a SS plate. Eventually the constant weight isside bonded to a SS plate. Eventually the constant weight isresponsible for the adhesive tape to slip down from the SSresponsible for the adhesive tape to slip down from the SSplate . This happen due to a split of the adhesive layer. It’splate . This happen due to a split of the adhesive layer. It’scalled as cohesive failure. Hence Shear test is a gauge ofcalled as cohesive failure. Hence Shear test is a gauge ofCohesive strength of the adhesiveCohesive strength of the adhesive

Hence the WB Acrylic PSA’s can have substantially differentproperties , especially in water submerged or high humidityenvironment

The loss of tack is important because it is going to control theinteraction between PSA and the Substrate / Backing , material

To overcome this issueThe monomers responsible ( soft monomers ) for the drop inTack are replaced by , Hard or Functional monomersThusMeth acrylic acid replaces acrylic acid to improve on removalefficiency by 50%Methacrylate replaces vinyl acetate to improve on removalefficiency by 70%

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To overcome this issueThe monomers responsible ( soft monomers ) for the drop inTack are replaced by , Hard or Functional monomersThusMeth acrylic acid replaces acrylic acid to improve on removalefficiency by 50%Methacrylate replaces vinyl acetate to improve on removalefficiency by 70%

AcrylicAcrylic EmulsionEmulsion

Are Polymerized in water (surfactant needed)They have Good properties similar to solutionacrylics but typically lower adhesion, tack and shear.The emulsions need to be Stabilized from biologicalattackThey are sensitive to water , and moistureLess expensive than solvent borne acrylics

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AcrylicAcrylic EmulsionEmulsion

Are Polymerized in water (surfactant needed)They have Good properties similar to solutionacrylics but typically lower adhesion, tack and shear.The emulsions need to be Stabilized from biologicalattackThey are sensitive to water , and moistureLess expensive than solvent borne acrylics

The emulsions need to be Stabilized from biological attackThey are sensitive to water , and moisture

TheThe WaterWater BorneBorne Acrylic AdhesiveAcrylic Adhesive film , that is produced on asubstrate by coating the emulsion and drying the same withapplication of heat.

The dried film of adhesive retains the additives , used forstabilizing the emulsion . The distribution of these chemicals andtheir tendency to absorb moisture in a aqueous environment ,results in rapid swell of adhesive film and substantial decrease inTack, adhesion and strength.

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The emulsions need to be Stabilized from biological attackThey are sensitive to water , and moisture

TheThe WaterWater BorneBorne Acrylic AdhesiveAcrylic Adhesive film , that is produced on asubstrate by coating the emulsion and drying the same withapplication of heat.

The dried film of adhesive retains the additives , used forstabilizing the emulsion . The distribution of these chemicals andtheir tendency to absorb moisture in a aqueous environment ,results in rapid swell of adhesive film and substantial decrease inTack, adhesion and strength.

NowNow

Let us have a glance at the Solvent based AcrylicPSA’s

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PSA

We willlook intoRubberbased

PSA’s abit later

ACRYLICACRYLIC

SOLVENT

2/20/2017 40

We willlook intoRubberbased

PSA’s abit later

We will look into Acrylic Solventbased PSA’s now

What is the difference between a solvent acrylic adhesive and aWhat is the difference between a solvent acrylic adhesive and awater based adhesive and when should I use each?water based adhesive and when should I use each?

Every roll of pressure-sensitive laminate and mounting adhesivehas one of two types of adhesive: a solvent-based acrylicadhesive (which has a solvent as its base liquid)ora water-based acrylic adhesive (which uses water as its baseliquid).

Solvent-based adhesives usually cost more, but may provideperformance characteristics that exceed what you really need.Use a solvent-based acrylic adhesives to protect against failurewhen mounting or laminating

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What is the difference between a solvent acrylic adhesive and aWhat is the difference between a solvent acrylic adhesive and awater based adhesive and when should I use each?water based adhesive and when should I use each?

Every roll of pressure-sensitive laminate and mounting adhesivehas one of two types of adhesive: a solvent-based acrylicadhesive (which has a solvent as its base liquid)ora water-based acrylic adhesive (which uses water as its baseliquid).

Solvent-based adhesives usually cost more, but may provideperformance characteristics that exceed what you really need.Use a solvent-based acrylic adhesives to protect against failurewhen mounting or laminating

A solvent-based adhesive is almost always recommended forinkjet prints because the ink-receptive coatings on the materialsare designed to absorb ink, which is 99% water.If you place a water-based adhesive on top of an inkjet coating,the coating will eventually wick the water from the adhesive,causing it to dry out and fail over time.On an outdoor inkjet graphic, water running down the edge of awater-based adhesive can sometimes dilute the adhesive,causing the edge of the graphic to wick. This can result in anundesirable edge-lift effect.

A solvent-based adhesive is more resistant to wicking, and willhold up longer outdoors.

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A solvent-based adhesive is almost always recommended forinkjet prints because the ink-receptive coatings on the materialsare designed to absorb ink, which is 99% water.If you place a water-based adhesive on top of an inkjet coating,the coating will eventually wick the water from the adhesive,causing it to dry out and fail over time.On an outdoor inkjet graphic, water running down the edge of awater-based adhesive can sometimes dilute the adhesive,causing the edge of the graphic to wick. This can result in anundesirable edge-lift effect.

A solvent-based adhesive is more resistant to wicking, and willhold up longer outdoors.

PSA

RUBBERRUBBER

EMULSION

Now let us go back to

We will discuss more aboutLatex Based PSA’s

In the next few slides

We have studied theseearlier

2/20/2017 43

We will discuss more aboutLatex Based PSA’s

In the next few slides

We have studied theseearlier

NowNowLet us see how the Rubber Based PSA’s are manufacturedLet us see how the Rubber Based PSA’s are manufactured

ChemicalFormula

ofNaturalRubber

We see that this is a very long chain molecule with a lot ofWe see that this is a very long chain molecule with a lot ofunsaturation or double bonds in it .unsaturation or double bonds in it .

Available in two forms

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Emulsion/ LatexEmulsion/ Latex Dry Rubber Base

Available in two forms

Don’t be Misled by “Latex Free” Claims

Consumer Health Information www.fda.gov/consumerDon’t be Misled by “Latex Free” Claims if you’re allergic tonatural rubber latex, FDA has good news for you:in the future, you are less likely to be misinformed about theabsence of this allergen in such products as medical devices.To avoid false assurancesabout this hazard to your health, FDA is recommending tomanufacturers to stop using the labels “latex-free” or “does notcontain latex”.The reason for this recommendation is that the agency is notaware of any tests that can show a product contains no naturalrubber latex proteins that can cause allergic reactions.

2/20/2017 45

Don’t be Misled by “Latex Free” Claims

Consumer Health Information www.fda.gov/consumerDon’t be Misled by “Latex Free” Claims if you’re allergic tonatural rubber latex, FDA has good news for you:in the future, you are less likely to be misinformed about theabsence of this allergen in such products as medical devices.To avoid false assurancesabout this hazard to your health, FDA is recommending tomanufacturers to stop using the labels “latex-free” or “does notcontain latex”.The reason for this recommendation is that the agency is notaware of any tests that can show a product contains no naturalrubber latex proteins that can cause allergic reactions.

Without a way to verify that a product is completely free ofthese proteins, a claim that it is “latex free” is scientificallyinaccurate and may be misleading.FDA’s final guidance document,(https://www.federalregister.gov/ articles/2014/12/02/2014-28265/recommendations-for-labeling-medicalproducts-to-inform-users-that-the product-or-product-container)issued

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Without a way to verify that a product is completely free ofthese proteins, a claim that it is “latex free” is scientificallyinaccurate and may be misleading.FDA’s final guidance document,(https://www.federalregister.gov/ articles/2014/12/02/2014-28265/recommendations-for-labeling-medicalproducts-to-inform-users-that-the product-or-product-container)issued

Difference Between Rubber andDifference Between Rubber and LatexLatexRubberRubber vsvs LatexLatex

Rubber and latex are both elastomers in which dimensions canbe changed largely when stressed, and which can be returned totheir original dimensions after the stress is removed. They fallinto the category of polymeric materials. Latex items and rubberitems can be distinguished by the method of production. Inaddition, latex and rubber can be differentiated from each other,because latex is the raw material for rubber. So, latex should beidentified first.

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Difference Between Rubber andDifference Between Rubber and LatexLatexRubberRubber vsvs LatexLatex

Rubber and latex are both elastomers in which dimensions canbe changed largely when stressed, and which can be returned totheir original dimensions after the stress is removed. They fallinto the category of polymeric materials. Latex items and rubberitems can be distinguished by the method of production. Inaddition, latex and rubber can be differentiated from each other,because latex is the raw material for rubber. So, latex should beidentified first.

LatexLatex

Latex is defined as a stable colloidal dispersion of a polymericsubstance in an aqueous medium. The most common latex is thesap, obtained from the Heveabrasiliensis tree. In latex, there aretwo systems, namely a dispersion medium and a dispersed phase.In latex, rubber particles are suspended in the aqueous medium.Rubber molecules are present as chains in the structure, andthere is free space in between chains.latex, is mixed with compounding agents (i.e. additives added toimprove the properties of latex).Generally, latex is used to make thin films

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LatexLatex

Latex is defined as a stable colloidal dispersion of a polymericsubstance in an aqueous medium. The most common latex is thesap, obtained from the Heveabrasiliensis tree. In latex, there aretwo systems, namely a dispersion medium and a dispersed phase.In latex, rubber particles are suspended in the aqueous medium.Rubber molecules are present as chains in the structure, andthere is free space in between chains.latex, is mixed with compounding agents (i.e. additives added toimprove the properties of latex).Generally, latex is used to make thin films

RubberRubberRubber is obtained from latex, which is tapped from trees. Themost common tree that is used to produce rubber isHeveabrasiliensis.The molecular structure of natural rubber is cis-1, 4-polyisoprene.Tapped latex is first diluted and then it is coagulated using anacid. After that, this coagulated latex is compressed in rollers, toremove water. The products are raw rubber sheets. These sheetsare taken to produce rubber items. Rubber sheets are mixed withcompounding agents, to impart the desired properties of the finalproduct.Both latex and rubber are water proof.

2/20/2017 49

RubberRubberRubber is obtained from latex, which is tapped from trees. Themost common tree that is used to produce rubber isHeveabrasiliensis.The molecular structure of natural rubber is cis-1, 4-polyisoprene.Tapped latex is first diluted and then it is coagulated using anacid. After that, this coagulated latex is compressed in rollers, toremove water. The products are raw rubber sheets. These sheetsare taken to produce rubber items. Rubber sheets are mixed withcompounding agents, to impart the desired properties of the finalproduct.Both latex and rubber are water proof.

At this moment let us study how Dry RubberBase PSA’s are Manufactured

Let’s have a look at the Rubber molecule yet again

2/20/2017 50

We see that this is a veryWe see that this is a verylong chain molecule withlong chain molecule witha lot of unsaturation ora lot of unsaturation ordouble bonds in it .double bonds in it .Hence it needs to beHence it needs to beprocessed to break theprocessed to break thelong chainlong chain

Dry Rubber Adhesive ManufacturingDry Rubber Adhesive ManufacturingProcess Flow ChartProcess Flow Chart

This is DryThis is DryNatural RubberNatural Rubber

Masticated onMasticated onTwo Roll MillTwo Roll MillFor about 30For about 30--

40 minutes40 minutes

NaturalNaturalRubber LatexRubber Latex

filteredfilteredpurified andpurified andcoagulatedcoagulated

Water andWater andrubberrubber

separatedseparated

Rubber sheetsRubber sheetsare then driedare then dried

2/20/2017 51

Masticated onMasticated onTwo Roll MillTwo Roll MillFor about 30For about 30--

40 minutes40 minutes

At this stageAt this stageResins+ A/O +Resins+ A/O +

PlasticizerPlasticizerAdded toAdded toRubberRubber

For about 40For about 40minutesminutes

The mixture isThe mixture ischarged to a sigmacharged to a sigmamixer and solventmixer and solventToluene is addedToluene is addedgradually withgradually with

continuous mixingcontinuous mixingFor about 3For about 3--4 hours4 hours

ReadyReadyAdhesive isAdhesive is

stored instored inbarrelsbarrelsBeforeBefore

CoatingCoating

Rubber MasticationRubber MasticationMastication, the process by which the viscosity of natural rubber is reduced to asuitable level, is an important step in the mixing process. Rubber polymers suchas Natural Rubber (NR) require mastication to reduce their viscosity/elasticityand to even out variations between different polymer lots. This process can besimulated by a torque rheometer.Compounds with curing agents are tested for minimum viscosity, the onset ofscorching and for the rate of cure.These tests allow the assessment of the initial flow properties of the sample: thetorque peak caused by the high resistance of polymer being sheared while stillcold. Then one can evaluate the process of mastication.The figure below combines the two mastication test runs for an easycomparison:Mastication of a natural rubber (“NR“) just under the influence of shear andtemperature;Mastication as above but with the additional influence of a chemical additivecalled “Renacit 7“ added to the polymer at a level of 0.5 %. This accelerates thebreakdown of the molecular structure and greatly reduces the mixing energy.

2/20/2017 52

Rubber MasticationRubber MasticationMastication, the process by which the viscosity of natural rubber is reduced to asuitable level, is an important step in the mixing process. Rubber polymers suchas Natural Rubber (NR) require mastication to reduce their viscosity/elasticityand to even out variations between different polymer lots. This process can besimulated by a torque rheometer.Compounds with curing agents are tested for minimum viscosity, the onset ofscorching and for the rate of cure.These tests allow the assessment of the initial flow properties of the sample: thetorque peak caused by the high resistance of polymer being sheared while stillcold. Then one can evaluate the process of mastication.The figure below combines the two mastication test runs for an easycomparison:Mastication of a natural rubber (“NR“) just under the influence of shear andtemperature;Mastication as above but with the additional influence of a chemical additivecalled “Renacit 7“ added to the polymer at a level of 0.5 %. This accelerates thebreakdown of the molecular structure and greatly reduces the mixing energy.

Mastication and softening are usually carried out in batches. The operation isdone either in large enclosed mixing machines or on rubber mills. Thepreeminent example of an enclosed machine is the Banbury (registeredtrademark) mixer, consisting of heavy steel counter rotating paddles in anhourglass-shaped chamber, holding up to one-half ton of rubber. Rubber millshave two large horizontally opposed, closely spaced steel cylinders, up to 3metres (10 feet) long, that are rotated slowly in opposite directions and atsomewhat different speeds. Rubber is sheared and softened in the gapbetween the paddles and wall of the Banbury mixer and in the gap betweenthe two cylinders in the roll mill.

2/20/2017 53

Mastication and softening are usually carried out in batches. The operation isdone either in large enclosed mixing machines or on rubber mills. Thepreeminent example of an enclosed machine is the Banbury (registeredtrademark) mixer, consisting of heavy steel counter rotating paddles in anhourglass-shaped chamber, holding up to one-half ton of rubber. Rubber millshave two large horizontally opposed, closely spaced steel cylinders, up to 3metres (10 feet) long, that are rotated slowly in opposite directions and atsomewhat different speeds. Rubber is sheared and softened in the gapbetween the paddles and wall of the Banbury mixer and in the gap betweenthe two cylinders in the roll mill.

Mastication is an important step in the manufacture of rubber compounds. Itdecreases the viscosity of rubber, promotes good dispersion of fillers andchemicals, and increases compound plasticity. In this paper the authorssummarize the present knowledge about mastication of rubber and peptizingagents and present the recent work carried out in their laboratories on thesetopics. It is demonstrated that peptizing agents act in the mechanochemical andthermoxidative breakdown of elastomers as radical acceptors at lowtemperatures and as oxidation catalysts at high temperatures.

2/20/2017 54

Mastication is an important step in the manufacture of rubber compounds. Itdecreases the viscosity of rubber, promotes good dispersion of fillers andchemicals, and increases compound plasticity. In this paper the authorssummarize the present knowledge about mastication of rubber and peptizingagents and present the recent work carried out in their laboratories on thesetopics. It is demonstrated that peptizing agents act in the mechanochemical andthermoxidative breakdown of elastomers as radical acceptors at lowtemperatures and as oxidation catalysts at high temperatures.

Rubber Mixing MillThe basic design and construction of the mills has been subjected to continuousimprovements which have permitted them to keep pace with the day to day needsof the industry.

Available in sizes varying from 6"x16" to 26"x84" for compounding, warming,sheeting of various grades and types of rubber and other material.In the category of Mill also available in different sizes are Refiners, Crackers,Grinders, Rubber Breakers Mills and Asbestos Shelters.

Salient features include chilled cast iron rolls, frames, caps, journal boxes in highgrade casting, gear of cast iron or casting and MS steel fabricated as per dulyrequirements special alloy leaded bronze bushing suitable to take heavyseparating forces and to give longer wear life, gravity/forced or flood lubricatingsystems rolls suitable for steam heating/water cooling, positive pull back fail safesystem for emergency stop. Special accessories include strip cutters, stockdividing guides, stock blanders etc

2/20/2017 55

Rubber Mixing MillThe basic design and construction of the mills has been subjected to continuousimprovements which have permitted them to keep pace with the day to day needsof the industry.

Available in sizes varying from 6"x16" to 26"x84" for compounding, warming,sheeting of various grades and types of rubber and other material.In the category of Mill also available in different sizes are Refiners, Crackers,Grinders, Rubber Breakers Mills and Asbestos Shelters.

Salient features include chilled cast iron rolls, frames, caps, journal boxes in highgrade casting, gear of cast iron or casting and MS steel fabricated as per dulyrequirements special alloy leaded bronze bushing suitable to take heavyseparating forces and to give longer wear life, gravity/forced or flood lubricatingsystems rolls suitable for steam heating/water cooling, positive pull back fail safesystem for emergency stop. Special accessories include strip cutters, stockdividing guides, stock blanders etc

Specification of Rubber Mixing MillSize of Roll Capacity Kgs. R.P.M.of Motor Friction Ratio Electric6” x 13”8” x 18”10” x 24”12” x 30”14” x 36”16” x 42”18” x 48”22” x 60”24” x 78”26” x 84”

3 / 67 / 1015 / 2020 / 3030 / 4550 / 6075 / 9090 / 110130 / 150160 / 180

29232121191715121210

1 : 1 . 151 : 1 . 151 : 1 . 181 : 1 . 181 : 1 . 181 : 1 . 181 : 1 . 181 : 1 . 181 : 1 . 181 : 1 . 18

7.5102030406075120175225

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Specification of Rubber Mixing MillSize of Roll Capacity Kgs. R.P.M.of Motor Friction Ratio Electric6” x 13”8” x 18”10” x 24”12” x 30”14” x 36”16” x 42”18” x 48”22” x 60”24” x 78”26” x 84”

3 / 67 / 1015 / 2020 / 3030 / 4550 / 6075 / 9090 / 110130 / 150160 / 180

29232121191715121210

1 : 1 . 151 : 1 . 151 : 1 . 181 : 1 . 181 : 1 . 181 : 1 . 181 : 1 . 181 : 1 . 181 : 1 . 181 : 1 . 18

7.5102030406075120175225

Rubber Dispersion KneadersUnderstanding the needs of plastics & rubber processingindustry and developing fully indigenous solution to cater tothese needs has always been the prime target. When the needwas felt for a mixer capable of : hard mixing from processcompounding view point, We developed Dispersion Kneader.Dispersion Mixer can be employed in a wide range ofmaterial mixing, ranging from low viscosity adhesives tohigh viscosity rubber. Internal Mixer series to a highlydeveloped range of Dispersion Kneaders for rubber and otherpolymers with high productivity and consistently goodmixing with minimum electricity consumption.

2/20/2017 57

Rubber Dispersion KneadersUnderstanding the needs of plastics & rubber processingindustry and developing fully indigenous solution to cater tothese needs has always been the prime target. When the needwas felt for a mixer capable of : hard mixing from processcompounding view point, We developed Dispersion Kneader.Dispersion Mixer can be employed in a wide range ofmaterial mixing, ranging from low viscosity adhesives tohigh viscosity rubber. Internal Mixer series to a highlydeveloped range of Dispersion Kneaders for rubber and otherpolymers with high productivity and consistently goodmixing with minimum electricity consumption.

Model Main TotalWeight Working Rotor Tilt Tilt Tilt Air

MotorH.P. Comp.HP Cap.

AppCap.Ltrs. R.P.M. Method Angle Motor H.P.

5 ltrs.

15 ltrs.

25 ltrs.

35 ltrs.

55 ltrs.

75 ltrs.

110 ltrs.

125 ltrs.

7.5

25

40

60

75/100

100/125

125/150

150/175

8

30

45

75

125

225

170

265

5

15

25

35

55

110

75

125

33.28

33.28

33.28

33.28

33.28

33.28

33.28

33.28

Pneumatic

Screw

Screw

Screw

Screw

Screw

Screw

Screw

120

110

110

110

110

110

110

110

-

1.5

2

2

3

5

7.5

7.5

2

2

2

2

5

7.5

10

12.5

1 Ton

3 ,,

5 ,,

6 ,,

7 ,,

8 ,,

8 ,,

13 ,,

2/20/2017 58

Model Main TotalWeight Working Rotor Tilt Tilt Tilt Air

MotorH.P. Comp.HP Cap.

AppCap.Ltrs. R.P.M. Method Angle Motor H.P.

5 ltrs.

15 ltrs.

25 ltrs.

35 ltrs.

55 ltrs.

75 ltrs.

110 ltrs.

125 ltrs.

7.5

25

40

60

75/100

100/125

125/150

150/175

8

30

45

75

125

225

170

265

5

15

25

35

55

110

75

125

33.28

33.28

33.28

33.28

33.28

33.28

33.28

33.28

Pneumatic

Screw

Screw

Screw

Screw

Screw

Screw

Screw

120

110

110

110

110

110

110

110

-

1.5

2

2

3

5

7.5

7.5

2

2

2

2

5

7.5

10

12.5

1 Ton

3 ,,

5 ,,

6 ,,

7 ,,

8 ,,

8 ,,

13 ,,

Sigma mixer (kneader) to produce uniform mixing and kneadingheavier viscosity materials. The Sigma mixture is suitable formany applications like mixing, etc.

The sigma mixer have application to produce highly viscousmaterials like different kinds of adhesives, etc.

2/20/2017 59

The Electrical Load required for Solvent dissolvedThe Electrical Load required for Solvent dissolvedNatural Rubber AdhesiveNatural Rubber Adhesive

Mastication onRubber MillConnected Load :15 HP = 11.25KwMastication Time: 30 minutesRubber Quantity :12 kgs

Mixing of Resins /A/O , other raw mat.on Rubber MillConnected Load : 15HP = 11.25 KwMixing Time : 90minutesTotal Quantity : 24kgs

Mixing of Dry Rubbercompound withSolvent TolueneConnected Load : 35HP = 26.25 KwMixing Time : 240minutesTotal SolutionQuantity : 48 kgs

60

Mastication onRubber MillConnected Load :15 HP = 11.25KwMastication Time: 30 minutesRubber Quantity :12 kgs

Mixing of Resins /A/O , other raw mat.on Rubber MillConnected Load : 15HP = 11.25 KwMixing Time : 90minutesTotal Quantity : 24kgs

Mixing of Dry Rubbercompound withSolvent TolueneConnected Load : 35HP = 26.25 KwMixing Time : 240minutesTotal SolutionQuantity : 48 kgs

20-02-2017

This means that

The Electrical Energy consumption ofRubber Mill : 11.25 kw x 120 minutes = 11.25 kw X 2 hrs =22.5 UnitsSigma Mixer : 26.25 X 240 minutes = 26.25X 4 hrs = 105unitsTotal Electrical Units = 127.5 , for 24 kgs of dry adhesive

= 5.31 units / kg = INR 37.18 / Kg

61

This means that

The Electrical Energy consumption ofRubber Mill : 11.25 kw x 120 minutes = 11.25 kw X 2 hrs =22.5 UnitsSigma Mixer : 26.25 X 240 minutes = 26.25X 4 hrs = 105unitsTotal Electrical Units = 127.5 , for 24 kgs of dry adhesive

= 5.31 units / kg = INR 37.18 / Kg

20-02-2017

This means

The Man Power cost ofOn Rubber Mill : 1+1 person x 120 minutes = 2 men X 2 hrs =2 X ( (10000/25 = 400 / day/person = 50/hr/person x2= INR100 / 24 kg of adhesive = INR 4.00 / kg )

On Sigma Mixer : 1 person X 240 minutes = 1 manX 4 hrs =1 X ( (10000/25 = 400 / day/person = 50/hr/person x1X 4 hrs =INR 200 / 24 kg of adhesive = INR 8.00 / kg )Total Manpower cost = 300 , for 24 kgs of dry adhesive

= INR 12.50 / Kg

62

This means

The Man Power cost ofOn Rubber Mill : 1+1 person x 120 minutes = 2 men X 2 hrs =2 X ( (10000/25 = 400 / day/person = 50/hr/person x2= INR100 / 24 kg of adhesive = INR 4.00 / kg )

On Sigma Mixer : 1 person X 240 minutes = 1 manX 4 hrs =1 X ( (10000/25 = 400 / day/person = 50/hr/person x1X 4 hrs =INR 200 / 24 kg of adhesive = INR 8.00 / kg )Total Manpower cost = 300 , for 24 kgs of dry adhesive

= INR 12.50 / Kg

20-02-2017

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At this moment let us study how LatexRubber Base PSA’s are Manufactured

Let’s have a look at the Rubber molecule yet again

2/20/2017 65

We see that this is a very longWe see that this is a very longchain molecule with a lot ofchain molecule with a lot ofunsaturation or double bonds in itunsaturation or double bonds in it..But it is available in a emulsionBut it is available in a emulsionformform

Latex Rubber Adhesive ManufacturingLatex Rubber Adhesive ManufacturingProcess Flow ChartProcess Flow Chart

NaturalNaturalRubber LatexRubber Latex

Purified andPurified andprocessed byprocessed byCentrifugalCentrifugal

methodmethod

At this stageAt this stageResinsResins

emulsions +emulsions +and otherand other

Raw MaterialsRaw Materialsin emulsionin emulsion

formformAnd Mixed inAnd Mixed in

a simplea simpleagitator for 30agitator for 30

minutesminutes

2/20/2017 66

At this stageAt this stageResinsResins

emulsions +emulsions +and otherand other

Raw MaterialsRaw Materialsin emulsionin emulsion

formformAnd Mixed inAnd Mixed in

a simplea simpleagitator for 30agitator for 30

minutesminutes

ReadyReadyAdhesive isAdhesive is

stored instored inbarrelsbarrelsBeforeBefore

CoatingCoating

2/20/2017 67

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Natural RubberNatural RubberLatex EmulsionLatex Emulsion

AcrylicAcrylicEmulsionsEmulsions

2/20/2017 70

Man madeMan madeEmulsionsEmulsions

Natural occurringNatural occurringEmulsionEmulsion

ContainContainSurfactants toSurfactants tomanufacturemanufacturestablestableemulsionsemulsions

Natural Rubber LatexNatural Rubber LatexEmulsionEmulsion

Acrylic EmulsionsAcrylic Emulsions

NaturallyNaturallyoccurringoccurringEmulsionsEmulsionsNo externalNo externalsurfactantssurfactants

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ContainContainSurfactants toSurfactants tomanufacturemanufacturestablestableemulsionsemulsions

NaturallyNaturallyoccurringoccurringEmulsionsEmulsionsNo externalNo externalsurfactantssurfactants

Adhesive coated filmAdhesive coated filmafter drying still Containafter drying still ContainSurfactants orSurfactants orhydrophilic ingredientshydrophilic ingredientsused while manufacturingused while manufacturingadhesive emulsionsadhesive emulsions

Natural Rubber LatexNatural Rubber LatexEmulsionEmulsion

Acrylic EmulsionsAcrylic Emulsions

Adhesive coated filmAdhesive coated filmafter drying do notafter drying do notContain any SurfactantsContain any SurfactantsOr hydrophilicOr hydrophilicingredientsingredients

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Adhesive coated filmAdhesive coated filmafter drying still Containafter drying still ContainSurfactants orSurfactants orhydrophilic ingredientshydrophilic ingredientsused while manufacturingused while manufacturingadhesive emulsionsadhesive emulsions

Adhesive coated filmAdhesive coated filmafter drying do notafter drying do notContain any SurfactantsContain any SurfactantsOr hydrophilicOr hydrophilicingredientsingredients

In chemistry, water is considered to be the universal solvent,and materials that are hydrophilic can dissolve in it.

In chemistry, water is considered to be the universalsolvent, and materials that are hydrophilic can dissolvein it.hydrophilic - having a strong affinity for water; tendingto dissolve in, mix with, or be wetted by water.

The word hydrophilic describes that fact that polar substances docombine with water molecules.Let's take a closer look at that definition. Water is a polarmolecule, which means that it carries a partial charge between itsatoms.Oxygen, as an electronegative atom, draws the electrons of eachbond closer to its core, thus creating a more negative charge.Therefore, any materials with a charge, be it negative or positive,will be able to interact with water molecules to dissolve.(Think of how salt dissolves in water. This is due to the chargesof the ions sodium and chlorine.)2/20/2017 73

The word hydrophilic describes that fact that polar substances docombine with water molecules.Let's take a closer look at that definition. Water is a polarmolecule, which means that it carries a partial charge between itsatoms.Oxygen, as an electronegative atom, draws the electrons of eachbond closer to its core, thus creating a more negative charge.Therefore, any materials with a charge, be it negative or positive,will be able to interact with water molecules to dissolve.(Think of how salt dissolves in water. This is due to the chargesof the ions sodium and chlorine.)

Hydrophilic and hydrophobic molecules are also knownas polar molecules and non polar molecules, respectively.Some hydrophilic substances do not dissolve. This type ofmixture is called a colloid.

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Natural rubber latex is basically a colloidal dispersion of rubber hydrocarbonin an aqueous medium. The chemical composition of rubber hydrocarbon hasbeen identified as linear crs-1,4-polyisoprene of high molecular weight, and itis present in latex as molecular aggregates in the form of discrete particleswhich are usually spherical in shape with diameters ranging from 15nm to 3pm(Lucas, 1938).In addition to the rubber hydrocarbon fresh NR latex contains proteins, lipids,sugars, carotenoids, mineral salts, enzymes and numerous other nitrogenoussubstances in addition to water & rubber hydrocarbon. Most of these non-rubber constituents are dissolved in the aqueous phase of the latex, some areadsorbed at the surface of the rubber particles and the others are suspended inthe latex.It has been established that in fresh NR latex the non rubber constituents whichare adsorbed on the rubber particles are mainly proteins and lipid materials,possibly in the form of a complex.At least some of these proteins are phosphoproteins (Tunniclife, 1954) and atleast some of the lipids are phospholipids (Smith, 1954).

2/20/2017 75

Natural rubber latex is basically a colloidal dispersion of rubber hydrocarbonin an aqueous medium. The chemical composition of rubber hydrocarbon hasbeen identified as linear crs-1,4-polyisoprene of high molecular weight, and itis present in latex as molecular aggregates in the form of discrete particleswhich are usually spherical in shape with diameters ranging from 15nm to 3pm(Lucas, 1938).In addition to the rubber hydrocarbon fresh NR latex contains proteins, lipids,sugars, carotenoids, mineral salts, enzymes and numerous other nitrogenoussubstances in addition to water & rubber hydrocarbon. Most of these non-rubber constituents are dissolved in the aqueous phase of the latex, some areadsorbed at the surface of the rubber particles and the others are suspended inthe latex.It has been established that in fresh NR latex the non rubber constituents whichare adsorbed on the rubber particles are mainly proteins and lipid materials,possibly in the form of a complex.At least some of these proteins are phosphoproteins (Tunniclife, 1954) and atleast some of the lipids are phospholipids (Smith, 1954).

Structure of Natural Rubber particle

IntroductionIntroductionBased on the reactions of NR latex towards various chemical treatments "andphysical techniques the following structure has been proposed for the structureof natural rubber particle.

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The principal phospholipids of the NR latex are of the lecithin typeand they are strongly adsorbed on to the surfaces of the rubberparticles. They are thought to be intermediaries by which theproteins are anchored on to the rubber particles. The adhesionbetween the proteins and the adsorbed lecithin has been accountedfor the fact that at the pH of fresh latex the lipid layer carries aslight overall positive charge, whereas the proteins, being on thealkaline side of their iso electric point are negatively charged, sothat ionic interaction between the two layers is possible(Blackley, 1966).

2/20/2017 77

The principal phospholipids of the NR latex are of the lecithin typeand they are strongly adsorbed on to the surfaces of the rubberparticles. They are thought to be intermediaries by which theproteins are anchored on to the rubber particles. The adhesionbetween the proteins and the adsorbed lecithin has been accountedfor the fact that at the pH of fresh latex the lipid layer carries aslight overall positive charge, whereas the proteins, being on thealkaline side of their iso electric point are negatively charged, sothat ionic interaction between the two layers is possible(Blackley, 1966).

Chemical composition of fresh NR LatexBeing a natural product the composition of NR latex would varydepending on various factors such as clone, season, soil conditions,fertilizer application techniques and tapping frequencies etc. Assuch it is not possible to give an exact composition for the NRlatex. However a typical composition can always be suggested asgiven below; % by weight of latexDry rubber content 30-35Proteinous substances 1-1.5Lipids 1-2.5Sugars 1Inorganic ions 1Water 60-65

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Chemical composition of fresh NR LatexBeing a natural product the composition of NR latex would varydepending on various factors such as clone, season, soil conditions,fertilizer application techniques and tapping frequencies etc. Assuch it is not possible to give an exact composition for the NRlatex. However a typical composition can always be suggested asgiven below; % by weight of latexDry rubber content 30-35Proteinous substances 1-1.5Lipids 1-2.5Sugars 1Inorganic ions 1Water 60-65

All these non-rubber substances are distributed between threeprincipal phases. The average percentage of each of these threephases is given below:% by weight of latexRubber phase 35Aqueous phase 55Lutoid phase 10Lutoid phase can only be seen in fresh NR latex since the lutoidparticles which constitute the lutoid phase are very sensitive tovarious factors such as dilution, ammoniation and heat. Lutoidparticles are slightly larger than the rubber particles and areirregular in shape. Chemically, they appear to be mainly water. Inaddition to that they contain various other substances such ascarotenoids, acids, mineral salts, proteins and even rubber particles.The boundary of a lutoid particle is a semipermeable membraneand hence they are osmotically sensitive.2/20/2017 79

All these non-rubber substances are distributed between threeprincipal phases. The average percentage of each of these threephases is given below:% by weight of latexRubber phase 35Aqueous phase 55Lutoid phase 10Lutoid phase can only be seen in fresh NR latex since the lutoidparticles which constitute the lutoid phase are very sensitive tovarious factors such as dilution, ammoniation and heat. Lutoidparticles are slightly larger than the rubber particles and areirregular in shape. Chemically, they appear to be mainly water. Inaddition to that they contain various other substances such ascarotenoids, acids, mineral salts, proteins and even rubber particles.The boundary of a lutoid particle is a semipermeable membraneand hence they are osmotically sensitive.

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Preservation of NR latexPreservation of NR latex is normally achieved by adding up to1.0%(w/w on the aqueous phase) of ammonia. Ammonia being agood biocide has several advantages; it• controls the proliferation of bacteria• neutralises the free acids formed in the latex• helps in the precipitation of heavy metals such as Mg• hydrolyses the interfacial proteins and phospholipids, therebymaking the latex more stable.

The hydrolysis of phospholipids has been found to occur morerapidly than that of the proteins, and as a consequence, by thetime the latex reaches the latex reception point of the industrialuser, the phospholipids of ammoniated and concentrated latexhave been converted to fatty-acid soaps (Blackley, 1966).2/20/2017 81

Preservation of NR latexPreservation of NR latex is normally achieved by adding up to1.0%(w/w on the aqueous phase) of ammonia. Ammonia being agood biocide has several advantages; it• controls the proliferation of bacteria• neutralises the free acids formed in the latex• helps in the precipitation of heavy metals such as Mg• hydrolyses the interfacial proteins and phospholipids, therebymaking the latex more stable.

The hydrolysis of phospholipids has been found to occur morerapidly than that of the proteins, and as a consequence, by thetime the latex reaches the latex reception point of the industrialuser, the phospholipids of ammoniated and concentrated latexhave been converted to fatty-acid soaps (Blackley, 1966).

Among other products, much of the proteins remainunhydrolysed. The interfacial film at this stage consists of asoap/protein mixture, and the composition of this interfacialfilm changes as the latex ages.

Colloidal instability of latices:The simplest type of colloid system is a dispersion of one phasein a second phase, in which the disperse phase is in a state ofdispersion such that at least one dimension is in the rangebetween lnm and lOOOnm. Colloids are generally classifiedlyophobic (there is no tendency for the disperse phase to mix withthe dispersion 11 medium) or lyophillic (there is a strongtendency for the disperse phase to mix with the dispersionmedium). The most important property of a lyophobic colloid isits colloid stability. Rubber latices are examples of lyophobiccolloids.2/20/2017 82

Among other products, much of the proteins remainunhydrolysed. The interfacial film at this stage consists of asoap/protein mixture, and the composition of this interfacialfilm changes as the latex ages.

Colloidal instability of latices:The simplest type of colloid system is a dispersion of one phasein a second phase, in which the disperse phase is in a state ofdispersion such that at least one dimension is in the rangebetween lnm and lOOOnm. Colloids are generally classifiedlyophobic (there is no tendency for the disperse phase to mix withthe dispersion 11 medium) or lyophillic (there is a strongtendency for the disperse phase to mix with the dispersionmedium). The most important property of a lyophobic colloid isits colloid stability. Rubber latices are examples of lyophobiccolloids.

The factors which determine the colloid stability of a rubber latexare essentially those which determine the colloid stability of anylyophobic colloid.In latices, as in colloidal dispersions in general, frequentencounters between particles occur due to Brownianmovement,to gravity (creaming and sedimentation), and to convection.Whether such encounters results in permanent contact, or whetherthe particles rebound and remain free, is determined by the forceswhich are operative between the particles. If the attractive forces,which are assumed to be of London Van der Waals type, arelarger than the repulsive forces, interaction between two or moreparticles may first cohere to give a loose aggregate and thensubsequently to give a little larger particle.

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The factors which determine the colloid stability of a rubber latexare essentially those which determine the colloid stability of anylyophobic colloid.In latices, as in colloidal dispersions in general, frequentencounters between particles occur due to Brownianmovement,to gravity (creaming and sedimentation), and to convection.Whether such encounters results in permanent contact, or whetherthe particles rebound and remain free, is determined by the forceswhich are operative between the particles. If the attractive forces,which are assumed to be of London Van der Waals type, arelarger than the repulsive forces, interaction between two or moreparticles may first cohere to give a loose aggregate and thensubsequently to give a little larger particle.

Nature of stability of lyophobic colloids A lyophobic colloid issaid to be stable if it persists as a colloidal dispersion overa period of time. However, all lyophobic colloids arethermodynamically unstable because of their high interfacial freeenergy which is a result of the high ratio of interfacial area tovolume of the disperse phase. Aggregation or the flocculation ofthe dispersed particles, which brings about a reduction of theinterfacial area and free energy is therefore thermodynamicallyfavorable. As mentioned earlier the stability/flocculation behaviorof a lyophobic colloid is governed by the various attractive andrepulsive forces between the particles. Amongst the possiblebasic interparticle forces involved in colloidal systems of alltypes, the following can be considered as the important forceswhich are operative between the rubber particles in NR latex;

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Nature of stability of lyophobic colloids A lyophobic colloid issaid to be stable if it persists as a colloidal dispersion overa period of time. However, all lyophobic colloids arethermodynamically unstable because of their high interfacial freeenergy which is a result of the high ratio of interfacial area tovolume of the disperse phase. Aggregation or the flocculation ofthe dispersed particles, which brings about a reduction of theinterfacial area and free energy is therefore thermodynamicallyfavorable. As mentioned earlier the stability/flocculation behaviorof a lyophobic colloid is governed by the various attractive andrepulsive forces between the particles. Amongst the possiblebasic interparticle forces involved in colloidal systems of alltypes, the following can be considered as the important forceswhich are operative between the rubber particles in NR latex;

Centrifuged Latex of 60% of Dry Rubber Content(CENEX)Processing of natural rubber latex into high quality latexconcentrate of 60% dry rubber content is done throughcentrifugation. Centrifuging involves the separation ofpreserved field latex into two fractions, one containing theconcentrated latex of more than 60% dry rubber and the othercontaining 4-6% dry rubber. Centrifuged latex is todayavailable commercially in two different verities with highammonia (min.0.7% of ammonia) and low ammonia (max.0.3% of ammonia). The former is preserved solely withammonia and later contains one or more preservatives besidesammonia.

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Centrifuged Latex of 60% of Dry Rubber Content(CENEX)Processing of natural rubber latex into high quality latexconcentrate of 60% dry rubber content is done throughcentrifugation. Centrifuging involves the separation ofpreserved field latex into two fractions, one containing theconcentrated latex of more than 60% dry rubber and the othercontaining 4-6% dry rubber. Centrifuged latex is todayavailable commercially in two different verities with highammonia (min.0.7% of ammonia) and low ammonia (max.0.3% of ammonia). The former is preserved solely withammonia and later contains one or more preservatives besidesammonia.

LA latex has several advantages which include better quality,lower cost of production by way of savings in preservatives,acid and low cost of effluent treatment.

Grades and applicationsHigh Ammonia (HA) -Foam products, dipped goods, adhesives,elastic thread, household and industrial gloves, balloons, rubberbands and finger caps.

Low Ammonia (LATZ) - Preferred for all applications when deammonia is necessary for product manufacture. Requirementfor centrifuged natural rubber latex is given in the table.

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LA latex has several advantages which include better quality,lower cost of production by way of savings in preservatives,acid and low cost of effluent treatment.

Grades and applicationsHigh Ammonia (HA) -Foam products, dipped goods, adhesives,elastic thread, household and industrial gloves, balloons, rubberbands and finger caps.

Low Ammonia (LATZ) - Preferred for all applications when deammonia is necessary for product manufacture. Requirementfor centrifuged natural rubber latex is given in the table.

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Adhesive coated film after dryingAdhesive coated film after dryingstill Contain Surfactants orstill Contain Surfactants orhydrophilic ingredients used whilehydrophilic ingredients used whilemanufacturing adhesive emulsionsmanufacturing adhesive emulsions

Acrylic EmulsionsAcrylic Emulsions Natural Rubber LatexEmulsion

Adhesive coated film afterAdhesive coated film afterdrying do not Contain anydrying do not Contain anySurfactantsSurfactantsOr hydrophilic ingredientsOr hydrophilic ingredients

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Dry WB Acrylic Adhesive FilmAdhesive Film( coated on PET FilmPET Film )


Acrylic EmulsionsAcrylic Emulsions Natural Rubber LatexEmulsion



On exposure to water or high Humidity

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On exposure to water or high Humidity

Dry WB Acrylic Adhesive FilmAdhesive Film( coated on PET FilmPET Film )Swelling due to moistureabsorbed

Dry WB Acrylic Adhesive FilmAdhesive Film( coated on PET FilmPET Film )Relatively no Swelling

The ease in handling gravureThe ease in handling gravureOrOrKiss coating with Myer barKiss coating with Myer bar

TheThe ease in handling latex based ( water borne )ease in handling latex based ( water borne )

Easy to cleaningEasy to cleaning

Require Much lesser time for cleaningRequire Much lesser time for cleaning

Fast change over'sFast change over's

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The ease in handling gravureThe ease in handling gravureOrOrKiss coating with Myer barKiss coating with Myer bar

TheThe ease in handling latex based ( water borne )ease in handling latex based ( water borne )

Easy to cleaningEasy to cleaning

Require Much lesser time for cleaningRequire Much lesser time for cleaning

Fast change over'sFast change over's

The key advantages to using waterborneThe key advantages to using waterborne adhesives

they posses good resistance to heat and abrasionProvide excellent adhesionLow toxicity and flammability due to low VOC levelsHelp reducing air emissionthese coatings cost less than solvent-borne coatingsless coating is required to cover the same surface areaThe pot life of waterborne products is relatively longand unused coatings can be preserved in a sealed container forfuture useThe coating machine components can be cleaned easily withwater or water-based solutions and do not require any solvent.

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The key advantages to using waterborneThe key advantages to using waterborne adhesives

they posses good resistance to heat and abrasionProvide excellent adhesionLow toxicity and flammability due to low VOC levelsHelp reducing air emissionthese coatings cost less than solvent-borne coatingsless coating is required to cover the same surface areaThe pot life of waterborne products is relatively longand unused coatings can be preserved in a sealed container forfuture useThe coating machine components can be cleaned easily withwater or water-based solutions and do not require any solvent.

How the Coating Process of Solvent Borne and Water Borne isHow the Coating Process of Solvent Borne and Water Borne isdifferentdifferent

Let us first look at the ways , of coating solventcoating solvent borne

The coating processcoating process largely depends upon the

The ViscosityThe solids contentThe rheologyAndThe loading of ingredients other than the main polymerThe particle sizeThe solvent evaporation temp

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How the Coating Process of Solvent Borne and Water Borne isHow the Coating Process of Solvent Borne and Water Borne isdifferentdifferent

Let us first look at the ways , of coating solventcoating solvent borne

The coating processcoating process largely depends upon the

The ViscosityThe solids contentThe rheologyAndThe loading of ingredients other than the main polymerThe particle sizeThe solvent evaporation temp

The coating process alsocoating process also depends upon the

The coat weight , either wet or dry the type of substrate , like paper, film, fabric, or foil etc. the type of solvent associated with the adhesive

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However the most popular methods employed forcoating solventcoating solvent borne are

Gravure CoatingGravure Coating

A schematic design is displayed here

Its most suitable for lower coatingweights ( 0.3 to 4.0 gsm ) , such asPrimer coating , release coating ,printing etc.Coating weight across the width andlength is precisely controlled.The coat weight depends on theCoating solids content , viscosity ,solvent evaporation rate , and thegravure cell structure or size.

Drying TunnelDrying Tunnel

Coated webCoated web

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A schematic design is displayed here

Its most suitable for lower coatingweights ( 0.3 to 4.0 gsm ) , such asPrimer coating , release coating ,printing etc.Coating weight across the width andlength is precisely controlled.The coat weight depends on theCoating solids content , viscosity ,solvent evaporation rate , and thegravure cell structure or size.

Adhesive TrayAdhesive Tray

Doctor’s bladeDoctor’s blade

Web to beWeb to becoatedcoated

Gravure RollerGravure Roller


The AdvantagesThe Advantages

1. Its most suitable for lower coatingweights ( 0.3 to 4.0 gsm )

2. Coating weight across the widthand length is precisely controlled.

3. Faster speeds4. Relatively quick changeovers5. Easy to operate

Drying TunnelDrying Tunnel

Coated webCoated web

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1. Its most suitable for lower coatingweights ( 0.3 to 4.0 gsm )

2. Coating weight across the widthand length is precisely controlled.

3. Faster speeds4. Relatively quick changeovers5. Easy to operate Adhesive TrayAdhesive Tray

Doctor’s bladeDoctor’s blade

Web to beWeb to becoatedcoated

Gravure RollerGravure Roller


The disadvantagesThe disadvantages1. Max coat wt possible is 10-12 gsm2. The liquid coating level in the tray has to be monitored and maintained3. In case of very fast drying solvents , chances of premature drying of the

coating in the gravure cells is possible , that could be a cause of concern ,4. Coat wt variation / no coating etc can cause rejection due to above.5. One has to take at most care while handing , low coat wt , coatings ,

especially like silicone coating . A silicone coating batch may contain just 1to 3 % solids , and the rest all is solvent.

6. The film of paper generates a lot of static electricity , while passing overrubber rollers / Idler rollers. The static eliminators have to play a verycrucial role here .

7. A smallest static discharge here can lead to a major fire , because , thehighly inflammable solvents are just across , in the coating tray.

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The disadvantagesThe disadvantages1. Max coat wt possible is 10-12 gsm2. The liquid coating level in the tray has to be monitored and maintained3. In case of very fast drying solvents , chances of premature drying of the

coating in the gravure cells is possible , that could be a cause of concern ,4. Coat wt variation / no coating etc can cause rejection due to above.5. One has to take at most care while handing , low coat wt , coatings ,

especially like silicone coating . A silicone coating batch may contain just 1to 3 % solids , and the rest all is solvent.

6. The film of paper generates a lot of static electricity , while passing overrubber rollers / Idler rollers. The static eliminators have to play a verycrucial role here .

7. A smallest static discharge here can lead to a major fire , because , thehighly inflammable solvents are just across , in the coating tray.


Comma CoatingComma CoatingThis method is most suitablehigher coating weights.

The coating weight across thewidth can be controlled with in 2grams variation

The coat weight depends on theThe gap set between theThe metering and the applicatorroller,Coating solids content , viscosity, solvent evaporation rate .

Applicator roll

Metering roll

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Comma CoatingComma CoatingThis method is most suitablehigher coating weights.


The coat weight depends on theThe gap set between theThe metering and the applicatorroller,Coating solids content , viscosity, solvent evaporation rate .

Comma CoatingComma Coating


1. This method is most suitablehigher coating weights.

2. The coating weight acrossthe width can be controlledwith in 2 grams variation

Applicator roll

Metering roll

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Comma CoatingComma Coating




Comma CoatingComma CoatingThe DisadvantagesThe Disadvantages

1. The coating nip has to be precisely controlled.2. Any foreign particle , dry adhesive can cause a problem

like snapping of web .this is because the web is passingbetween a very narrow gap created between applicator andmetering roll.

3. Dry adhesive particles towards the web edges can cause ,web snaps and high wastage.

4. Any leakage of adhesive from the chick plates at the edgescan cause uneven coating problems.

5. Higher change over timing6. Higher cost of cleaning , due to the consumption of

solvents

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Comma CoatingComma CoatingThe DisadvantagesThe Disadvantages

1. The coating nip has to be precisely controlled.2. Any foreign particle , dry adhesive can cause a problem

like snapping of web .this is because the web is passingbetween a very narrow gap created between applicator andmetering roll.

3. Dry adhesive particles towards the web edges can cause ,web snaps and high wastage.

4. Any leakage of adhesive from the chick plates at the edgescan cause uneven coating problems.

5. Higher change over timing6. Higher cost of cleaning , due to the consumption of

solvents

Reverse Roller coatingReverse Roller coatingThis method is also mostsuitable higher coating weights.


The coat weight depends on theThe gap set between theThe metering and the applicatorroller, Coating solids content ,viscosity , solvent evaporationrate .

Applicatorroll

Metering roll

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Reverse Roller coatingReverse Roller coatingThis method is also mostsuitable higher coating weights.


The coat weight depends on theThe gap set between theThe metering and the applicatorroller, Coating solids content ,viscosity , solvent evaporationrate .

Reverse Roller coatingReverse Roller coatingThe AdvantagesThe Advantages



3. Relatively quick changeoverscompared to comma coating

Applicatorroll

Metering roll

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Reverse Roller coatingReverse Roller coatingThe AdvantagesThe Advantages



3. Relatively quick changeoverscompared to comma coating

Reverse Roller coatingReverse Roller coatingThe DisadvantagesThe Disadvantages

1. The coating nip has to be precisely controlled.2. Dry adhesive particles towards the web edges can cause ,

web snaps and high wastage.3. Any leakage of adhesive from the chick plates at the edges

can cause uneven coating problems.4. Higher change over timing5. Higher cost of cleaning , due to the consumption of solvents

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Reverse Roller coatingReverse Roller coatingThe DisadvantagesThe Disadvantages

1. The coating nip has to be precisely controlled.2. Dry adhesive particles towards the web edges can cause ,

web snaps and high wastage.3. Any leakage of adhesive from the chick plates at the edges

can cause uneven coating problems.4. Higher change over timing5. Higher cost of cleaning , due to the consumption of solvents


Floating Knife coating

This method isgenerally used for nonadhesive coatings

Backup rolls

Floating Knife

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This method isgenerally used for nonadhesive coatings

Backup rolls


Floating Knife coatingFloating Knife coating

The Advantages

1. This is the mosteasy method to coat

2. Generally used forFabric based web

3. Fast changeovers4. No snaps5. Low wastage

Backup rolls

Floating Knife

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Floating Knife coatingFloating Knife coating

The Advantages

1. This is the mosteasy method to coat

2. Generally used forFabric based web

3. Fast changeovers4. No snaps5. Low wastage

Backup rolls



Disadvantages

1. Suitable only forhigh coat weights

2. Suitable forstronger webs likefabrics

Backup rolls

Floating Knife

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Disadvantages

1. Suitable only forhigh coat weights

2. Suitable forstronger webs likefabrics

Backup rolls

Environmental Multi-Media AnalysisThe Main Environmental Advantages of water based PSAs1. The reduction in VOC emissions and hazardous wastes.the scientific, environmental, and industrial communities about thenet effect on the environment of converting from solvent-based to waterbased adhesive coatings.The modification of a manufacturing process to enable the use of waterbased coating materials has an impact on the facility's multi-mediaemissions and discharges. The evaluation of multi-media wastegenerated in all phases of a manufacturing process, from raw materialextraction to end product use, is called environmental multi-mediaanalysis. Such a process is normally conducted using either historicalmaterial, process, and emissions data from an existingplant, or data that are projected for a model plant. The completion of anenvironmental multi-media analysis is beyond the scope of this report,however, the issues that would be examined and resolved by such ananalysis are reviewed in the following sections.

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Environmental Multi-Media AnalysisThe Main Environmental Advantages of water based PSAs1. The reduction in VOC emissions and hazardous wastes.the scientific, environmental, and industrial communities about thenet effect on the environment of converting from solvent-based to waterbased adhesive coatings.The modification of a manufacturing process to enable the use of waterbased coating materials has an impact on the facility's multi-mediaemissions and discharges. The evaluation of multi-media wastegenerated in all phases of a manufacturing process, from raw materialextraction to end product use, is called environmental multi-mediaanalysis. Such a process is normally conducted using either historicalmaterial, process, and emissions data from an existingplant, or data that are projected for a model plant. The completion of anenvironmental multi-media analysis is beyond the scope of this report,however, the issues that would be examined and resolved by such ananalysis are reviewed in the following sections.

Environmental Multi-Media AnalysisThe Main Environmental Advantagesof waterbased PSAs

Air EmissionsThe retrofit of solvent-based adhesive coating equipment to processwaterbased materials can reduce both the number and size of VOCemissions &nts in a manufacturing facility."

First, by replacing current solvent-based PSAs with waterbased, thelevel of VOCs emitted from the coating operation may be reduced. Inplants with fully enclosed coating equipment (relatively rare), thisreduction can be very accurately measured. In the majority of plants, thiscomponent of reduced VOC emissions can be estimated usingemissions factors and mass balance

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Air EmissionsThe retrofit of solvent-based adhesive coating equipment to processwaterbased materials can reduce both the number and size of VOCemissions &nts in a manufacturing facility."

First, by replacing current solvent-based PSAs with waterbased, thelevel of VOCs emitted from the coating operation may be reduced. Inplants with fully enclosed coating equipment (relatively rare), thisreduction can be very accurately measured. In the majority of plants, thiscomponent of reduced VOC emissions can be estimated usingemissions factors and mass balance


Calculations. Solvent-based adhesives range from 20 to 70 percent solids(median of 40 percent) and may range in density from 7.0 to 7.5 lb/gal.Also, since waterbased adhesives may generally be cleaned with lessvolatile (Le. Lower vapor pressure) solvents or even water, the fugitiveemissions from equipment cleaning processesMay be decreased. Again, such reductions can be broadly estimated,although not precisely measured.Sources have identified that emissions from cleaning operationsresult in less than 10 percent of the total facility’s emissions!The largest source of emissions from solvent-based adhesive coatingprocesses, drying oven solvent emissions, can be dramatically reduced,or even eliminated, by a transition to water based coating materials.

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Calculations. Solvent-based adhesives range from 20 to 70 percent solids(median of 40 percent) and may range in density from 7.0 to 7.5 lb/gal.Also, since waterbased adhesives may generally be cleaned with lessvolatile (Le. Lower vapor pressure) solvents or even water, the fugitiveemissions from equipment cleaning processesMay be decreased. Again, such reductions can be broadly estimated,although not precisely measured.Sources have identified that emissions from cleaning operationsresult in less than 10 percent of the total facility’s emissions!The largest source of emissions from solvent-based adhesive coatingprocesses, drying oven solvent emissions, can be dramatically reduced,or even eliminated, by a transition to water based coating materials.

This emissions can generally be accurately measured,either through stack testing fur large facilities, or through engineeringcalculations in smaller shops. The elimination of drying oven solventvapor emissions would, in turn, eliminate the need for costly recoveryor incineration equipment on oven exhaust stacks. Finally,miscellaneous sources of solvent emissions such as solvent storage,handling, and transfer, adhesive mixing; and fugitive equipment leakswill be eliminated or duced.These air emission reductions are generally acknowledged to bepossible in any conversion from solvent-based to waterbased products.However, the true net reductions are equipment, material, and facilitydependent, and will be affected by the volume of products converted,the current capture and destruction efficiencies for solvent vaporemissions, and any solvent content in water based coating materials.

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This emissions can generally be accurately measured,either through stack testing fur large facilities, or through engineeringcalculations in smaller shops. The elimination of drying oven solventvapor emissions would, in turn, eliminate the need for costly recoveryor incineration equipment on oven exhaust stacks. Finally,miscellaneous sources of solvent emissions such as solvent storage,handling, and transfer, adhesive mixing; and fugitive equipment leakswill be eliminated or duced.These air emission reductions are generally acknowledged to bepossible in any conversion from solvent-based to waterbased products.However, the true net reductions are equipment, material, and facilitydependent, and will be affected by the volume of products converted,the current capture and destruction efficiencies for solvent vaporemissions, and any solvent content in water based coating materials.

Wastewater Treatment ConsiderationsInformation sources provide conflicting report of the net effect of awater based retrofit on wastewater generation. One approachmaintains that the wastewater volume generated from water basedadhesives may be comparatively lower than for solvent-based adhesivessince the volume of wastewater is often reduced by evaporation beforedisposal? However, another source stated that the volume of wastesgenerated from water based operations was no different thansolvent-based operations.Also, any facility engaged in formulating their own water-basedadhesives onsite will likely generate an additional wastewater streamduring the water de-ionization process.

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Wastewater Treatment ConsiderationsInformation sources provide conflicting report of the net effect of awater based retrofit on wastewater generation. One approachmaintains that the wastewater volume generated from water basedadhesives may be comparatively lower than for solvent-based adhesivessince the volume of wastewater is often reduced by evaporation beforedisposal? However, another source stated that the volume of wastesgenerated from water based operations was no different thansolvent-based operations.Also, any facility engaged in formulating their own water-basedadhesives onsite will likely generate an additional wastewater streamduring the water de-ionization process.

Solid WasteSolid wastes generated from adhesive coating processes (both waterbased and solvent-based) are comprised of make-ready, slittingexcesses, and some reject materials. Each of these materials maycontain some residual vehicle (solvent or water) from the adhesivecoating. Facilities which operate solvent-based processes usuallyassume for emissionscalculations purposes that 100 percent of the solvent is evaporated duringthe drying/curing stage. However, a confidential source stated thatapproximately 0.5 to 1.0 percent solvent remains in the solvent-basedadhesive-coated product after drying. Since some of this material isshipped off site as solid waste, it is possible that some solvent isintroduced to the landfill.The overall affect of converting solvent-based coating lines to waterbased on solid waste generation is unclear. One reasonable conclusionis that non-hazardous solid waste generation may increase due tothe fact that wastes which were previously classified as hazardous (dueto contamination with solvents) would be re-classified as non-hazardous (no solvent contamination).2/20/2017 111

Solid WasteSolid wastes generated from adhesive coating processes (both waterbased and solvent-based) are comprised of make-ready, slittingexcesses, and some reject materials. Each of these materials maycontain some residual vehicle (solvent or water) from the adhesivecoating. Facilities which operate solvent-based processes usuallyassume for emissionscalculations purposes that 100 percent of the solvent is evaporated duringthe drying/curing stage. However, a confidential source stated thatapproximately 0.5 to 1.0 percent solvent remains in the solvent-basedadhesive-coated product after drying. Since some of this material isshipped off site as solid waste, it is possible that some solvent isintroduced to the landfill.The overall affect of converting solvent-based coating lines to waterbased on solid waste generation is unclear. One reasonable conclusionis that non-hazardous solid waste generation may increase due tothe fact that wastes which were previously classified as hazardous (dueto contamination with solvents) would be re-classified as non-hazardous (no solvent contamination).

It should be noted, however, that these uncontaminated materials mayhave an increased potentialto be recycled, thus reducing total solid waste generation.6.2.4 Hazardous WasteWater based adhesives can significantly reduce the hazards andhazardous wastes involved with the use of solvent-based adhesives.Disagreeable odors, harmful vapors, flammabilityhazards, and hazardous wastes associated with solvent-based adhesiveswill be reduced, and may be eliminated, by the use of waterbasedmaterials? These reduced or eliminated hazardous wastes may includesolid waste (no longer contaminated with solvents), wastewater,recovered solvent from the drying ovens, and equipment cleaning wastes.

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It should be noted, however, that these uncontaminated materials mayhave an increased potentialto be recycled, thus reducing total solid waste generation.6.2.4 Hazardous WasteWater based adhesives can significantly reduce the hazards andhazardous wastes involved with the use of solvent-based adhesives.Disagreeable odors, harmful vapors, flammabilityhazards, and hazardous wastes associated with solvent-based adhesiveswill be reduced, and may be eliminated, by the use of waterbasedmaterials? These reduced or eliminated hazardous wastes may includesolid waste (no longer contaminated with solvents), wastewater,recovered solvent from the drying ovens, and equipment cleaning wastes.

Cleaning wastes may still be considered hazardous, althoughcontaminated with a less hazardous material (Le., toluene-soakedversus mineral oil-soaked rags). Where it is possible to replace ahazardous cleaning solvent with water, hazardous cleaning waste may beeliminated completely. Usually while still wet, waterbased adhesivescan be cleaned with warm water or a soap soi~ti~n?~ While thischaracteristic can dramatically decrease cleaning solvent usage, onefacility (which is cuficntly conducting cleaning solution tests using water,citrus-based cleaners, mineral oil, and mineral spirits) noted that theyfound soap and water solutions unable to effectively clean all coatingequipment on their waterbased adhesive lines?

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Cleaning wastes may still be considered hazardous, althoughcontaminated with a less hazardous material (Le., toluene-soakedversus mineral oil-soaked rags). Where it is possible to replace ahazardous cleaning solvent with water, hazardous cleaning waste may beeliminated completely. Usually while still wet, waterbased adhesivescan be cleaned with warm water or a soap soi~ti~n?~ While thischaracteristic can dramatically decrease cleaning solvent usage, onefacility (which is cuficntly conducting cleaning solution tests using water,citrus-based cleaners, mineral oil, and mineral spirits) noted that theyfound soap and water solutions unable to effectively clean all coatingequipment on their waterbased adhesive lines?

ReferencesPetriw, Gerhard. "Advances in waterborne acrylic PSAs throughexperimental design" Tappi Journal, 73 (12). TAPPL Nmss, GA.December 1990.Vetterl, Richard. "Fast-Tack WAC Waterborne Has Good Green Strength"Adhesives Age, 32 (2). Communication Channels, Inc. Atlanta, GA.March 1990.Trip Repod to Nashua Corporation, Omaha, NE, by TRCEnvironmental Corporation. February 12, 1993.McMinn, B.W. and J.B. Vitas. Improved Equipment Cleaning in Coatedand Laminated Substrate Manufacturing Facilities (Phase I). EPA-600/R-94-007 (NTIS PB94-141157).Air and Energy Engineering Research Laboratq, Research Triangle Park,NC. January 1994.Bond, Karen. "Rubber-to-Metal Waterbanre Eliminates Emissions andOdors" Adhesives Age, 32

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ReferencesPetriw, Gerhard. "Advances in waterborne acrylic PSAs throughexperimental design" Tappi Journal, 73 (12). TAPPL Nmss, GA.December 1990.Vetterl, Richard. "Fast-Tack WAC Waterborne Has Good Green Strength"Adhesives Age, 32 (2). Communication Channels, Inc. Atlanta, GA.March 1990.Trip Repod to Nashua Corporation, Omaha, NE, by TRCEnvironmental Corporation. February 12, 1993.McMinn, B.W. and J.B. Vitas. Improved Equipment Cleaning in Coatedand Laminated Substrate Manufacturing Facilities (Phase I). EPA-600/R-94-007 (NTIS PB94-141157).Air and Energy Engineering Research Laboratq, Research Triangle Park,NC. January 1994.Bond, Karen. "Rubber-to-Metal Waterbanre Eliminates Emissions andOdors" Adhesives Age, 32

References(2). Communication Channels Inc. Atlanta, GA. February 1990.Zimmer, David J. and Judith S. Morphy. "The solventless approachto adhesive compliance"Tappi Journul, 71 (12). TAPPI. Norcross, GA. December 1988."Waterborne Cuts Cleanup and Eliminates ComplianceCosts" Adhesives Age, 30 (2).Communication Channels, Inc. Atlanta, GA. February 1987.' Available in Appendix C of Reference 4.

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ConclusionConclusion

This exercise was essential to understand , as to how the ,This exercise was essential to understand , as to how the ,Natural Rubber Latex based Adhesives filmsNatural Rubber Latex based Adhesives filmsDiffer from Water Based Acrylic AdhesiveDiffer from Water Based Acrylic Adhesive film

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Natural Rubber Latex PSA's do they perform ?

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Transcript of Natural Rubber Latex PSA's do they perform ?