GB550491A - Improvements in or relating to the bleaching of textiles - Google Patents

Abstract

550,491. Bleaching textiles. DU PONT DE NEMOURS & CO., E. T., REICHERT, J. S., and ELSTON, A. A. July 4, 1941, No. 8461. [Class 15 (ii)] Cotton is bleached by treatment with an aqueous solution, of not more than 2 volume strength, of an organic carboxylic peracid or a salt thereof. Such solutions are obtainable as described in Specification 550,490. Alternatively, they may be produced in presence of the material to be bleached by adding an organic acid anhydride to the aqueous bleaching bath containing a compound yielding active oxygen. In examples, (1) grey cotton muslin is treated for 1 hour with an aqueous solution at 82‹C. containing soap and sodium carbonate, rinsed, immersed for 15 minutes in a 2 vol. aqueous solution at 82.2‹C. of monoperphthalic acid of pH =8.0, rinsed, dried and ironed ; (2) cotton muslin is treated as in (1) with an aqueous solution of soap and sodium carbonate and then subjected to two successive immersions for 15 minutes in a 0.5 vol. aqueous solution at 82.2‹C. of monoperphthalic acid of pH =8.0, the material being rinsed between the two immersions and finally rinsed, dried and ironed ; (3) cotton cloth, carrying a pattern of red, orange and yellow naphthol and blue vat colours, is treated as in (1) with an aqueous solution of soap and sodium carbonate, rinsed, squeezed and then subjected to two successive immersions for 15 minutes in a 1 vol. aqueous solution at 82.2‹C. of monoperphthalic acid of pH =7.0 to 8.0, the material being rinsed and squeezed between the two immersions and finally rinsed, dried and ironed ; (4) cotton muslin is given the customary treatment in a boiling alkaline solution and then immersed for 6 hours in a 0.25 vol. aqueous solution at 82.2‹C. of peracetic acid of pH=6.2; a satisfactory bleach is obtained in the first halfhour ; (5) cotton muslin is given the customary treatment in a boiling alkaline solution and then immersed for 2 hours in a 0.25 vol. aqueous solution at 50‹C. of peracetic acid of pH = 7.0 ; (6) a braid made of strips of cotton cloth carrying a pattern of red naphthol and blue vat colours braided with undyed strips is immersed for 1 hour in a 0.25 vol. aqueous solution at 65.5‹C. of peracetic acid of pH =5.0, rinsed and dried ; (7) cotton muslin is subjected to an alkali boil, bleached by treatment for 15 minutes with a 0.0825 vol. aqueous solution at. 82.2‹C. of peracetic acid of pH=3.0 to 4.0 and further treatment for 1 hour with a 0.16 vol. aqueous solution at 82.2‹C. of peracetic acid of pH =3.0 to 4.0, dried, rinsed and ironed ; comparative tests with processes in which the first treatment is replaced by a hydrogen peroxide or a sodium hypochlorite bleach are described ; (8) cotton muslin is subjected to an alkali boil and bleached by several passages through a 1 vol. aqueous solution at 32.2‹C. of peracetic acid of pH =8.0, followed by expression of the excess liquor and storage for 15 minutes at 32.2‹C. Specification 451,115 also is referred to.