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, yousuf_te@yahoo.com

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 : ퟏퟓퟎퟎ풄
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:
(퐂ퟔ퐇ퟏퟎ퐎ퟓ)n + nNaOH ---> (퐂ퟔ퐇ퟗ퐎ퟒ−퐎퐍퐚)n + n퐇ퟐO
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:
(퐂ퟔ퐇ퟗ퐎ퟒ−퐎퐍퐚)n + n퐂퐒ퟐ ----> (퐂ퟔ퐇ퟗ퐎ퟒO-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:
(퐂ퟔ퐇ퟗ퐎ퟒO-SC-SNa)n + n퐇ퟐO ---> (퐂ퟔ퐇ퟏퟎ퐎ퟓ)n + nC퐒ퟐ + 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:
퐍퐚ퟐ퐒퐨ퟒ : 15-20%
퐇ퟐ퐒퐨ퟒ : 7-10%
퐙퐧퐒퐨ퟒ : 1-5%
Glucose : 1-2%
Spinning Bath Temperature : ퟒퟎ−ퟓퟓퟎ퐜

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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