GB507664A - Improvements relating to the bleaching of cellulosic fibres - Google Patents

Abstract

507,664. Bleaching cellulose fibres. HUGHES, C. L. (Buffalo Electro-Chemical Co., Inc.) Nov. 16, 1937, No. 31489. [Class 15 (ii)] Bleaching of cellulosic fibres, natural or artificial, including paper pulp, is effected by saturating them with a solution containing, per litre, at least 20 cc. of hydrogen peroxide, 30 per cent by volume, or equivalent amounts of per-compounds normally generating hydrogen peroxide in solution, and an alkali content equivalent to at least 5 grams of caustic soda; the solution being maintained at room temperature, i.e. up to 125‹ F., and the goods being permitted to bleach without any substantial evaporation of the solution. Specified alkalies used are sodium silicate, sodium pyrophosphate, di- and tri-sodium phosphates, sodium bicarbonate and borax and to the bath so obtained may added other substances, including other alkalies, such as caustic soda, soda ash, ammonia or organic bases, and soaps, sulphonated oils, solvents or wetting-out agents. In examples: (1) the goods are saturated with an aqueous solution containing, per 100 litres, 5 litres of hydrogen peroxide, 30 per cent by volume, and 6 kilograms of sodium silicate solution of 42‹ BÚ., the surplus solution is removed and the goods are permitted to stand until the desired bleach is effected; (2) the goods are saturated with an aqueous solution containing, per litre, 20 cc. of hydrogen peroxide, 30 per cent by volume, 30 cc. of sodium silicate solution of 42‹ BÚ. and 10 to 20 grams of caustic soda, the surplus solution is removed so that the goods retain 50 to 130 per cent of solution based on their original weight; the goods are permitted to stand for, about 8 to 16 hours, rinsed and similarly .treated with a second Solution contining per litre, 40 cc. of hydrogen peroxide, 30 per cent by volume, 60 cc. of sodium silicate solution of 42‹ BÚ. and 20 to 40 grams of caustic soda, and permitted to stand for 2 to 12 hours.