MANUFACTURING PROCESS FLOW OF REGENERATED FIBRES
REGENERATED FIBRES
Regenerated fiber is created by dissolving the cellulose area of plant fiber in chemicals and making it into fiber again (by viscose method). Since it consists of cellulose like cotton and hemp, it is also called "regenerated cellulose fiber."
Regenerated fibres are made from cellulose polymers that occur naturally in plants such as cotton, wood, hemp and flax. Materials like rayon and acetate two of the first man made fibres to be produced were made from cellulose polymers. Viscose, rayon, acetate Rayon Modal and Lyocell are all regenerated fibres.
(lets see brief explanation of all these fibers)
VISCOSE RAYON
INTRODUCTION:-
Viscose rayon was the first regenerated man-made fiber.
It is developed in 1910 in united state.
Rayon is a manufactured fiber composed of “regenerated cellulose”.
Regenerated fiber contains 50% cellulosic contain and 50% chemical contain.
CHARACTERISTICS OF VISCOSE RAYON
High absorbent
Soft and comfortable
Easy to dye
Good drapability
TYPES OF RAYONS
High wet modulus rayon
Polynosic rayon
Specialty rayon
Super absorbent rayon
Tencel rayon
Lyocell
MANUFACTURING PROCESS OF VISCOSE RAYON
The process of manufacturing viscose rayon consist of the following steps mentioned, in the order that they are carried out:
the various steps involved in the process of manufacturing viscose are explained below,
cellulose is extracted from wood pulps, is purified and then formed into thin sheets.
The sheets are soaked in caustic soda or sodium hydroxide solution convert into “alkali cellulose”.
The alkalized pulp sheets are shredded into crumbs and are aged for alkali cellulose to react with oxygen.
The aged alkali cellulose reacts with a chemical known as carbon- disulphide.
These reactions change the solution into a viscose liquid solution. The name viscose is derived from this solution.
Viscose solution is forced through the spinnerets into an acid bath of sulphuric acid to form hardened fiber filaments.
The filaments can be twisted to form yarns and then wound on to spools for weaving.
The filaments can also be cut into shorter lengths to make staple fibers.
PROPERTIES OF VISCOSE RAYON:
it has a serrated round shape with a smooth surface. The manufacturer can control the shape and lusture of the fiber.
The fiber has good strength and good abrasion resistance.
The fiber has greater elasticity than the natural cellulosic fibers.
Good drapability.
Good heat conductor and good absorbent fiber and therefore, it are suitable for summer wear.
Easily attack soil and dirt.
Mildew attacks the fiber.
The fiber affects concentrated alkalis, hot dilute acid and cold concentrated acid.
Dyed easily.
USES OF VISCOSE RAYON:-
viscose rayon is commonly used for apparel made accessories, blouses, dresses, jackets, linings, slack shirts, sportwear, suits, ties, work cloths.
It is also used for bed spreads, blankets, curtains, draperies, home furnishings items, table cloths.
In industries uses, produce industrial products, medical surgical products, non woven products, tire cords.
ACETATE RAYON
INTRODUCTION:-
acetate rayon is modified and manufactured cellulosic fibre.
The fiber forming substance in acetate is called “cellulose acetate”.
Acetate rayons is a regenerated modified fiber.
If the cellulose is treated with acetic acid under certain conditions the free hydroxyl groups of cellulose are converted into ester groups. (oxygen bonded hydrogen)
RAW MATERIAL
cotton linters and wood pulp are the most common employed raw materials for the manufacture of acetate rayon.
MANUFACTURING PROCESS OF ACETATE RAYON:-
Acetate rayon is made by cellulose from wood pulp or cotton linters are used. It is purified, bleached and shredded.
The “shredded cellulose” fed into pretreatment tanks to be mixed with glacial acetic acid based on weight of cellulose and held in a particular time.
Acetic anhydride is added to pretreated cellulose in kneading machines known as acetylators.
Pretreated cellulose takes up a liquid form known as “cellulose acetate”.
This clear liquid of cellulose acetate is also known as “acid dope” is emptied into special storage tanks for aging.
Water is added to reduce the acid concentration and secondary acetate.
Secondary acetate, when mixed with water, gives out acetate precipitate in the form of small flakes.
The flakes are washed to remove excess acid and dried, and it is dissolve in acetone to form the spinning dope.
Dope is filtered and forced through the spinnerets into a warm air chamber, where acetone is evaporated and recovered.
Finally the acetate coagulates as it falls through the warm air chamber and filaments are twisted to form yarns.
PROPERTIES OF ACETATE RAYON:-
Acetate rayon medium eight with poor strength and abrasion resistance.
It has greater elasticity than rayon.
It needs to be washed carefully using mild detergents.
Mildew and insects attack in sunlight.
Only acetate dyes are used.
Garment should not be rubbed, wrong or squeezed.
USES OF ACETATE RAYON:-
acetate is used as apparel like lining, graduation gowns, neck ties, special occasion wear, ribbon, blouses and scarves.
It is also used as interiors like draperies, upholstery, quilted items.
MODAL FIBER
INTRODUCTION:-
Modal fiber is a cellulose fiber made up of wood pulp.
It is a regenerated fibre made from pure wooden small bits of the trees, especially as the European schneidar zelkova tree.
The generic name of madal fiber is modified viscose rayon.
Modal fiber is first introduced by lenzing A G company of Austria at 1930's.
It was imported from Slovakia, Hungary and Germany.
Now a day's lenzing Austria up with Rajasthan textile mills are supplying for Indian market.
MANUFACTURING PROCESS OF MODAL FIBER:-
Cellulose modal is manufactured by converting cellulose into a chemical compound.
Cellulose is dissolved with furfural acetic acid, xylose and sodium sulfate.
Mix all chemicals and press well.
Finally we use wet spinning or dry spinning.
PROPERTIES OF MODAL FIBER:-
high breaking strength.
Shrinkage resistance.
It is very soft, shiny in nature and silky feel.
Warm temperature.
Washed and ironed like cotton.
USES OF MODAL FIBER:-
modal fibers are commonly used for conveyor belts, washing tube pipes, apparel purpose and home furnishing items.
LYOCELL
INTRODUCTION:-
the lyocell was introduced in the year 1990's.
It was marketed as a type a rayon.
Commonly it is produced in both europe and united states.
PRODUCTION OF LYOCELL:-
MANUFACTURING PROCESS OF LYOCELL:-
A modification of wet spinning, method is used for making lyocell fiber.
First the cellulose wood pulp is dissolved in amine oxide.
The lyocell was spun into a weak bath of amine oxide. Amine oxide is a chemical with low toxicity and low skin irritation.
Here the cellulose wood pulp dissolves without changing the nature of the cellulose.
The solvent precipitates the fiber, after the spinning, the fiber is washed and dried.
PROPERTIES OF LYOCELL:-
AESTHETIC:
The lusture, length and diameter of lyocell fiber varied depending on the end-use.
Lyocell can be used by itself or blended with any natural or manufactured fiber.
DURABILITY
It breaking tenacity is 4.8 to 5.0 gms/denier
It loss12% in its strength.
Dry breaking elongation is 14 to 16% and wet breaking elongation is 16 to 18%
COMFORT:
lyocell fiber is very soft and smooth fiber.
This fiber is more comfortable for apparel product and commonly used for furnishing products.
APPEARANCE RETENTION:
the dimensional stability of lyocel fiber is good.
it wrinkle easily.
CARE:
lyocell can be either machine washed or dry cleaned.
USES OF LYOCELL:-
lyocell not quite twice as expensive per pound as viscose rayon.
Commonly lyocell fiber are used for professional wear, hosiery's, and casual wear, upholstery and window-treatment fabrics.
lyocell fiber is blended with wool and cotton.
Lyocell is also used for conveyor belts because of its strength and softness.
Its is also used for filters, printer blankets and medical dressing, etc.
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