BRIGHTENING AND SIZING PREPARATION FOR FINISHING VISCOSE

~By reactions in the polymer chains we have prepared copolymers containing acrylic ester units. With this objective we have carried out a hydrolysis of copolymers of acrylonitrile, methyl acrylate, and itaconic acid (ANC), in the form of Nitron fibre waste, in an aqueous alcohol solution of sodium hydroxide, with subsequent treatment of the hydrolyzed copolymer with a solution of sulfuric acid in an aliphatic alcohol [4]. Copolymers of similar composition have also been prepared by acid hydrolysis and subsequent esterification with an aliphatic alcohol [5]. Brightening and sizing preparations (BSP) based on these products ensure an improvement in the ability of viscose textile yarn to be processed; however, the methods for preparing such products are multistage, aggressive agents are used, and a need arises to utilize the wastes, particularly the dilute sulfuric acid. There are data in the literature about performing the hydrolysis of polyacrylonitrile in aqueous medium at an elevated temperature and pressure without a catalyst or in the presence of a powdered metal [6, 7]. By this method, copolymers were obtained which contained only carboxyl, amide, and carboxylate groups. We have investigated the possibility of preparing copolymers containing acrylic ester units by high-temperature hydrolysis of an ANC in the presence of aliphatic alcohols and an appropriate catalyst. Hydrolysis of the ANC was carried out in a mixture of water and a lower monohydric aliphatic alcohol at 135-175°C for 6-10 h. As the catalyst we used aluminum chloride, ferric chloride, copper chloride, or zinc chloride, in an amount of 0.1-0.5% based on weight of the copolymer. In Fig. i we show the dependence of the overall degree of hydrolysis on reaction time at 135-175°C in the presence of 0.2% AICIs by wt. The hydrolysis process takes place via the stage of forming an insoluble, colorless gel; consequently, no compounds containing a system of conjugated bonds are formed during the course of reaction. The hydrolysis reaction is reversible; the ammonia which accumulates in the system displaces it in the direction of forming acrylamide units. According to evidence from IR spectroscopy, functional analysis, and elemental analysis, the water-soluble ANC which are obtained as a result of hydrolysis contain acrylic ester, ammonium acrylate, acrylamide, and acrylonitrile units. On investigating the viscosity characteristics of the ANC obtained, it was found that the relative viscosity of 1% aqueous solutions of the ANC is increased with increase in the carboxylate group content of the copolymer; the relative viscosity of the same solutions containing 100% NaCI by wt. is hardly changed (Fig. 2).