Bleaching of blended fabrics

In tropical countries like India synthetic fibres blended with cellulosic fibres fabrics are very popular due to their excellent combination of aesthetic properties and easy care properties. Thus, bleaching of blended fibre fabrics before further processing is an important step. Many of the preparatory processes used for natural and synthetic fibres have little or no application in preparation of blended fibre fabircs. 

Polyester fibre in blends with cellulosic fibres in the ratios of 65/35 and 50/50 are common construction. When cellulose portion is rayon, the blends rarely require 

Chlorine bleaching can be done at 1 -2°Tw bleaching powder solution for 2-3 h, which is followed by dechlorinating treatment. Sodium thiosulphate, acidic sodium sulphate, ammonia, etc. can be used as dechlorinating agents. 

Alkaline hydrogen peroxide bleaching is the most preferred system for polyester/ cotton blends and bleaching can be carried out on various equipment using batchwise, semi-continuous and continuous method. Table 6.9 shows conditions for bleaching 

The most effective method of bleaching polyester/cotton is sodium chlorite, which may be followed by peroxide bleaching. Chlorite bleaches the husk, but does not destroy them completely. Polyester/cotton blends may be bleached with sodium chlorite in long liquors and also by pad-steam process [Table 6.10]. The 

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