GB1266896A - - Google Patents

Abstract

1,266,896. Bleaching process. UGINE KUHLMANN. 7 March, 1969 [8 March, 1968], No. 12270/69. Addition to 1,073,165. Heading D1P. A process for bleaching grey, ligneous textile material which contains a high proportion of non cellulosic material for example lignin, pectins and hemi-cellulose such as flax, hemp and jute comprising impregnating the grey ligneous fibres with a solution comprising an alkali metal chlorite or alkaline earth metal chlorite, a peroxide or a per-salt as a stabiliser for the chlorite and a buffer salt, removing the excess material from the textile material, and allowing the textile material to remain at ambient or elevated temperatures before washing the same. Non ionic or anionic detergents may be added to the bleaching solution. In the case of fabrics, desizing by a diastasic treatment, or by chemical action using a per salt, peroxide or alkaline bromite may be effected prior to the bleaching with raw flaxes the treatment of the invention may be followed by an additional bleaching process with chlorite, hypochlorite, peroxide or other oxidizing or reducing agent to bring them to full whiteness. The buffer salt may be of a strong base and a weak acid such as acetates, phosphates, borates and alkali metal phthalates which may be present in amounts from 50 to 250% by weight of the anhydrous chlorite, so as to maintain the solution between pH 4.5 and 7 throughout the bleaching process. The bleaching treatment may be effected at 70 to 130‹C by, for example, steam. After the removal of the excess bleach solution, the material may retain 60 to 150% of its weight of the bleach solution. When the chlorite used is sodium chlorite it is present in the bleach solution preferably in the range of 4 to 10% by weight of the textile material and no preliminary treatment may be necessary. After the treatment the textile is washed with detergent solution or water which may be presoftened or softened by addition of sodium carbonate.