Textile bleaching
Encyclopedia
Textile bleaching is one of the stages in the manufacture of textile
s. All raw textile materials, when they are in natural form, are known as 'greige' material. This greige material will be with its natural color, odour and impurities that are not suitable for clothing materials. Not only the natural impurities will remain on the greige material but also the add-ons that were made during its cultivation, growth and manufacture in the form of pesticide
s, fungicide
s, worm killers, sizes, lubricant
s, etc.
The removal of these natural coloring matters and add-ons during the previous state of manufacturing is called scouring and bleaching.
and so on. Scouring removes all the waxes, pectins and makes the textile material hydrophilic or water absorbent. See also scouring wool
or hydrogen peroxide
. Natural fibres like cotton
, ramie
, jute
, wool
, bamboo
are all generally bleached with oxidative methods.
, Polyacrylics and Polyacetates can be bleached using reductive bleaching technology.
Textile
A textile or cloth is a flexible woven material consisting of a network of natural or artificial fibres often referred to as thread or yarn. Yarn is produced by spinning raw fibres of wool, flax, cotton, or other material to produce long strands...
s. All raw textile materials, when they are in natural form, are known as 'greige' material. This greige material will be with its natural color, odour and impurities that are not suitable for clothing materials. Not only the natural impurities will remain on the greige material but also the add-ons that were made during its cultivation, growth and manufacture in the form of pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s, fungicide
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
s, worm killers, sizes, lubricant
Lubricant
A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...
s, etc.
The removal of these natural coloring matters and add-ons during the previous state of manufacturing is called scouring and bleaching.
Scouring
Scouring is the first process carried out with or without chemicals, at room temperature or at suitable higher temperatures with the addition of suitable wetting agents, alkaliAlkali
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...
and so on. Scouring removes all the waxes, pectins and makes the textile material hydrophilic or water absorbent. See also scouring wool
Bleaching
The next process of decolorization of greige material in to a suitable material for next processing is called bleaching. Bleaching of textiles can be classified in to oxidative bleaching and reductive bleaching.Oxidative bleaching
Generally oxidative bleachings are carried out using sodium hypochlorite, sodium chloriteSodium chlorite
Sodium chlorite is a chemical compound used in the manufacture of paper.-Use:The main application of sodium chlorite is the generation of chlorine dioxide for bleaching and stripping of textiles, pulp, and paper. It is also used for disinfection of a few municipal water treatment plants after...
or hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
. Natural fibres like cotton
Cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....
, ramie
Ramie
Ramie is a flowering plant in the nettle family Urticaceae, native to eastern Asia. It is a herbaceous perennial growing to 1–2.5 m tall; the leaves are heart-shaped, 7–15 cm long and 6–12 cm broad, and white on the underside with dense small hairs—this gives it a silvery appearance;...
, jute
Jute
Jute is a long, soft, shiny vegetable fibre that can be spun into coarse, strong threads. It is produced from plants in the genus Corchorus, which has been classified in the family Tiliaceae, or more recently in Malvaceae....
, wool
Wool
Wool is the textile fiber obtained from sheep and certain other animals, including cashmere from goats, mohair from goats, qiviut from muskoxen, vicuña, alpaca, camel from animals in the camel family, and angora from rabbits....
, bamboo
Bamboo
Bamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....
are all generally bleached with oxidative methods.
Reductive bleaching
Reductive method of bleaching is done with Sodium hydrosulphite, a powerful reducing agent. Fibres like PolyamidePolyamide
A polyamide is a polymer containing monomers of amides joined by peptide bonds. They can occur both naturally and artificially, examples being proteins, such as wool and silk, and can be made artificially through step-growth polymerization or solid-phase synthesis, examples being nylons, aramids,...
, Polyacrylics and Polyacetates can be bleached using reductive bleaching technology.