Process of bleaching and desizing cotton gray goods with organic solvent degreasing and dewaxing and peroxygen bleaching

摘要

A multi-stage process for the dewaxing, desizing and partial bleaching of cottoncontaining goods prior to dyeing, printing or other finishing processes comprises the steps of continuously and rapidly passing the goods, preferably in open width, through a bath of a hydrocarbon or chlorinated hydrocarbon solvent and treating the goods with a bath of an aqueous alkaline solution of a peroxygen compound. The treatments may be effected in either order. The organic solvent may be at its boiling point and the goods may be squeezed at intervals during their passage through the solvent bath; the peroxygen bath also may be hot. The goods may be passed through two consecutive baths containing the solvent or may be passed through a bath containing the solvent and a system of rollers such that during their passage through the bath the goods are raised above the level of the liquid five times. The solvent retained in the goods may be removed by drying or may be flashed off by passing the goods through hot water, and may be subsequently recovered, the excess water being removed from the goods by mangles. The solvent may be chloroform, methylene chloride, ethylene trichloride or perchlorethylene. The goods may be subjected to a prolonged immersion in the aqueous bath or to a rapid impregnation, e.g. by padding, followed by steaming. Following the aqueous bath the goods may be rinsed several times, one of the rinses containing an acid. Goods which have been steamed after the aqueous bath may be kept hot up to a washing and rinsing step. The peroxygen compound may be unneutralized sodium peroxide, sodium percarbonate, sodium perborate or hydrogen peroxide and the aqueous bath may also contain sodium silicate and a condensation product of octyl cresol and ethylene oxide. The pH of the bath may be adjusted to 11-12 with alkali. The goods may be woven piece goods, loose fibre stock, yarn or knit goods and may comprise mixtures of cotton with viscose rayon. The aqueous bath for treating such mixed fibre goods may also contain sodium bicarbonate.