Textile Mirror

Bleaching process depends on some important conditions. Some important conditions are given below –         Concentration of the chemical.         M:L ratio.         P H of the liquor.         Temperature of the liquor.         Time of treatment.         Catalyst.

They are in two types as follows –         Oxidizing and         Reducing Oxidizing Bleaching Agent The chemical agents which remove coloring material from textile materials by oxidizing reaction and make the material pure white and bright and to increase absorbency power is called oxidizing bleaching agent. Ex: O 3 , Ca(OCl)Cl, H 2 O 2 , NaOCl, Ca(OCl) 2 , K 2 Cr 2 O 7 etc. Generally natural vegetable fibres are bleached by these bleaching agents. Reducing Bleaching Agent The chemicals which removes coloring materials from textile materials by reduction reaction and make the material pure white and bright and increase absorbency power is called reducing bleaching agent. Ex: H 2 S, FeSO 4 , NaHSO 4 , Na 2 SO 4 etc. Generally protein fibre i.e. silk, wool, etc. are bleached by these agents.

Bleaching is the 3 rd step of wet processing. The process by which the natural color of a fibre can be removed and make the textile material pure white and bright is called bleaching. Objects of bleaching There are many objects as follows –         To remove the natural color.         To make the fabric permanent white and bright.         To increase the absorbency power of the cloth.         To increase dye affinity.         To ensure level dyeing property.         To make the fabric suitable for the next subsequent process.

Singeing: Singeing is carried out rarely on knitted fabrics and frequently on yarns and woven fabrics. Instead of the traditional singeing process, it is possible to apply an enzymatic treatment (for cotton and lyocell fabrics), for example with cellulose, which uses chemical agents to corrode the fibre surface and remove the fuzz from the fabric.

Pretreatment : The process which is done to make the textile materials suitable for dyeing &printing .Such as singeing ,desizing ,scouring, bleaching etc. Why we do pretreatment/utilities of pretreatment: 1. High absorbency 2. Low ash contain 3. High degree of whiteness 4. Optimum swelling of fibre 5. Good dimensional stability 6. Minimum loss of degree of polymer (D.P) 7. Shorter reaction time 8. Less energy consumption 9. Less Labour time