Improvements in the treatment of linear super polyamides preparatory to dyeing

Abstract

Abstract Textile materials containing synthetic linear polyamide filaments or fibres are treated with an aqueous solution of a strong acid at a concentration high enough and for a sufficient time to produce an improvement in their dyeing affinities without substantial delustring. The aqueous solution is selected from the group consisting of sulphuric acid of 42-47 DEG Twaddell, hydrochloric acid of 14-16 DEG Tw., nitric acid of 25.5-30 DEG Tw., orthophosphoric acid of 10-12 volumes of acid of 1.75 specific gravity to 12 volumes of water, and formic acid of at least 65 volumes of acid of 1.2 specific gravity to 35 volumes of water, but less strong than 80 volumes of acid of 1.2 sp. gr. to 20 volumes of water. The treatment may be applied uniformly over a fabric or yarn or may be applied over local areas. Mixed fabrics, yarns, or fibres may be treated. The materials may be passed through the solution of acid, then through a mangle, through washing and neutralizing baths, and then to a drying device. The acid treatment may be effected at ordinary temperature. The polyamide yarns or fabrics may be dyed with Chlorazol Sky Blue FFS or Green G, Victoria Pure Blue BOS, Safranine TS, or Caledon Brilliant Purple 4S. The Provisional Specification describes also the treatment of synthetic linear polyamide materials with more concentrated acid solutions or with acid solutions at elevated temperatures, so as to produce delustring. Formaldehyde may be included in the acid. Antimony trichloride may be included in a solution of hydrochloric acid so as to obtain a weighting as well as delustring of the nylon materials.

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