Viscose rayon fiber production process

Welcome To My Presentation

Presentation On

Viscose Rayon Production

Presented By:

Md. Yousuf Hossain.

Id No. :120103063

Md. Yousuf Hossain, Green University Of Bangladesh, [email protected]

Viscose Rayon: Viscose Rayon is a re-generated cellulosic fiber. It is

a manmade fiber and it is produced from the

cellulose.

Viscose Rayon is also called as artificial silk.

Mainly viscose rayon is used as the alternatives

of natural silk fiber.

Pulp is the raw material which is produced from

the wood, seed hair, leaf, grasses and bamboo

which contain cellulose.


Characteristics of Viscose Fiber :

Highly absorbent.

Soft and comfortable.

Easy to dye .

Drapes well .

Versatile.

It does not shrink when heated

It is biodegradable.


Properties Of Viscose Fiber:

i. Dry Tenacity (GPD) : 2.5 to 3

ii. Wet Tenacity (GPD) : 40 to 50% less

iii. Moisture Regain : 13%

iv. Lusture : Light to bright

v. Elasticity : Good

vi. Melting Point : 𝟏𝟓𝟎𝟎𝒄

vii. Elongation Percentage : 20-25%


Raw Materials (Wood Pieces)

↓

Purification

↓

Pulp Preparation

↓

Steeping in NaOH

↓

Pressing

↓

Process Flow Chart In Viscose Rayon Production :

Although viscose rayon is a manmade fiber and it is

produced by a spinning process.


Shredding

↓

Aging

↓

Xanthation

↓

Dissolving

↓

Blending

↓

Ripening

↓

Filtration

↓


Deairation

↓

Spinning

↓

Neutralization

↓

Purification

↓

Finishing

↓

Winding


1. Steeping:

Cellulose pulp is immersed in 17-20% aqueous sodium

hydroxide (NaOH) at a temperature in the range of 18 to 25°C.

Reaction:

(𝐂𝟔𝐇𝟏𝟎𝐎𝟓)n + nNaOH ---> (𝐂𝟔𝐇𝟗𝐎𝟒 − 𝐎𝐍𝐚)n + n𝐇𝟐O

2. Pressing:

The swollen alkali cellulose mass is pressed to a wet weight

equivalent of 2.5 to 3.0 times the original pulp weight to obtain

an accurate ratio of alkali to cellulose.

3. Shredding:

This step provides increased surface area of the alkali cellulose,

thereby increasing its ability to react in the steps that follow.


4. Aging:

In this step the average molecular weight of the original pulp is reduced

by a factor of two to three.

5. Xanthation:

In this step the aged alkali cellulose crumbs are placed in vats and are

allowed to react with carbon-di-sulphide under controlled temperature

(20 to 30°C) to form cellulose xanthate.

Reaction:

(𝐂𝟔𝐇𝟗𝐎𝟒 − 𝐎𝐍𝐚)n + n𝐂𝐒𝟐 ----> (𝐂𝟔𝐇𝟗𝐎𝟒O-SC-SNa)n 6. Dissolving:

The yellow crumb is dissolved in aqueous caustic solution.

7. Ripening:

The viscose is allowed to stand for a period of time to "ripen". Two

important process occur during ripening:

Reaction:

(𝐂𝟔𝐇𝟗𝐎𝟒O-SC-SNa)n + n𝐇𝟐O ---> (𝐂𝟔𝐇𝟏𝟎𝐎𝟓)n + nC𝐒𝟐 + nNaOH

8. Filtering: The viscose is filtered to remove undissolved materials that might disrupt the spinning process or cause defects in the rayon filament. 9. Deairation: Bubbles of air entrapped in the viscose must be removed prior to extrusion or they would cause voids, or weak spots, in the fine rayon filaments. 10. Spinning - (Wet Spinning): Production of Viscose Rayon Filament. 11. Drawing: The rayon filaments are stretched while the cellulose chains are still relatively mobile.


Spinning Bath Composition Of Viscose Fiber:

𝐍𝐚𝟐𝐒𝐨𝟒 : 15-20%

𝐇𝟐𝐒𝐨𝟒 : 7-10%

𝐙𝐧𝐒𝐨𝟒 : 1-5%

Glucose : 1-2%

Spinning Bath Temperature : 𝟒𝟎 − 𝟓𝟓𝟎𝐜


End-Uses

It is used in many apparel end-uses.

Often blended with other fibers, and in hygienic

disposables where its high absorbency is of

great advantage.

It is used very little in home furnishing fabrics but in

the industrial field, because of its thermal stability.


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Viscose rayon fiber production process

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