Patent GB-734010-A (GB)
Title: Improvements in or relating to the production of shaped articles of regenerated cellulose
IPC: C08L1/22
Filed: 1952-04-22
Abstract: In the production of shaped articles such as filaments of regenerated cellulose from viscose spinning solutions, one or more water-soluble or water-dispersible acrylamido resins capable of being cured until they are no longer dispersible in water are added to the spinning solution, the latter extruded into an aqueous coagulating bath, and the filaments &c. o regenerated cellulose thus produced are heated to cure the resin associated with the cellulose.  The resin may be a polymerized acrylamide, or a polymerized derivative of acrylamide such as an N-alkyl acrylamide or a methylolacrylamide, or a copolymer of acrylamide or of derivatives thereof with another polymerizable monomer, or one of the corresponding methacrylamide polymers and copolymers. The alkyl group may contain up to 4 carbon atoms. Typical comonomers which may be used for copolymerization with the acrylamido or methacrylamido compounds include allyl alcohol, methyl vinyl ketone, the allyl acrylates and methacrylates such as hydroxyethyl acrylate, methyl acrylate, methyl methacrylate or ethyl acrylate; acrylonitrile, methacrylonitrile, allyl amine, styrene, the amino styrenes, vinyl pyridine, or vinyl chloride. The resin is preferably added after the ageing of the viscose is substantially complete, e.g. by injection into the stream of viscose flowing to the spinneret.  The proportion of resin may be 2-20 and preferably 5-15 per cent.  Any of the well-known acid accelerators may be used in the curing of the resin, e.g. diammonium hydrogen phosphate, triethanolamine hydrochloride, hydrochloric, phosphoric, oxalic, or tartaric acid, ammonium chloride, sulphate or thiocyanate.  The curing temperatures may be 120-175 and preferably 140-160 DEG  C.  In an example, 85 part, 170 part and 255 part portions of 10 per cent solids solutions in water of poly-(methylolacrylamide) resins of about 200, 700 and 3500 c.p. viscosity at 25 DEG  C. are added each to a 2000 part portion of viscose containing about 8.5 per cent cellulose, and the resulting solutions spun within about 2 hours after the resin addition into a coagulating bath containing 10 per cent sulphuric acid, 1 of zinc sulphate, 14 of sodium sulphate, 10 of glucose, and 65 of water.  The regenerated cellulose filaments thus obtained are washed in water, soaked in a 0.25 per cent solution of diammonium hydrogen phosphate and then heated at 150 DEG  C. until the resin in the filaments is cured, i.e. 5-30 minutes.  If polyacrylamide or other polymer or copolymer not containing methylol groups is used, the filaments are preferably treated with formaldehyde, either under non-curing conditions to form a methylolated resin in situ which is then cured later, or under curing conditions.  Yarn prepared from the resin bearing filaments may be woven before the after-treatment with formaldehyde.  In an example aqueous solutions of 10 per cent concentration of low, medium and high viscosity of polyacrylamides are added, each to a viscose of 8.5 per cent cellulose content to give spinning solutions containing 5-17 per cent resin, based on cellulose. Filaments are spun from these solutions in the usual manner, washed and dried.  The dried yarn is soaked in 37 per cent aqueous formaldehyde solution, one part cured at 150 DEG  C., another part soaked in 0.25 per cent diammonium hydrogen phosphate solution and cured at 150 DEG  C. and a third part soaked in oxalic acid solution prior to curing.  The process of the invention reduces the elongation of the fibres when wet and their water absorption when dry, and increases the crimp retention of staple fibre without more than 20 per cent reduction in the tensile strength of the fibre.  U.S.A. Specification 2,173,005 is referred to.