GB1080103A - Improved acrylonitrile composite fibers and method for producing the same - Google Patents

Abstract

1,080,103. Producing acrylonitrile composite fibres. MITSUBISHI RAYON CO. Ltd., and MITSUBISHI VONNEL & CO. Ltd. May 4, 1965 [May 7, 1964; July 16, 1964], No. 18695/65. Heading B5B. In the production of acrylonitrile composite filaments by simultaneously extruding into a gaseous evaporative medium or a liquid coagulating medium through the same spinneret orifice two spinning solutions containing acrylonitrile polymer components, the composition of the polymer component in one spinning solution differing from that in the other and the composite filaments thus formed being drawn and then subjected to shrinking treatment, the acrylonitrile polymer component in both spinning solutions comprises acrylonitrile which in one or both spinning solutions is copolymerized with a hydrophilic monomer, but the percentage by weight of copolymerized hydrophilic monomer in the copolymer in one solution is at least 3À5% higher than the percentage by weight of copolymerized hydrophilic monomer in the copolymer in the other solution. The proportion of copolymerized hydrophilic monomer in the copolymer in the first spinning solution is less than 45% by weight and the proportion of copolymerized acrylonitrile in the copolymer in the second spinning solution. The spinning solutions may be spun in such a manner that the components of the composite filaments thereby formed are disposed in eccentric or side-by-side relationship over the crosssection of the filaments. The composite fibres contain at least 50%, preferably over 80% by weight of acrylonitrile in the form of a polymer. The hydrophilic monomer copolymerized with acrylonitrile is neutral, water-soluble and non- ionizable. A saturated aqueous solution of the monomer should contain more than 15% of the latter at 25‹ C. Filaments of a homopolymer made from the monomer should absorb more than 6% of their dry weight of moisture when exposed to an atmosphere of 65% relative humidity at 25‹ C. The hydrophilic monomer used may be an amide having in the molecule an ethylenically unsaturated group copolymerizable with acrylonitrile. Examples of such monomers are N-vinyl-N-methyl formamide, N-vinyl-methyl acetamide, N-vinyl pyrrolidone, N-vinyl caprolactam N-vinyl piperidine, acrylamide, methacrylamide, N-methyl and N,N- dimethyl acrylamide, N-acryl morpholine, N- acrylthiomorpholine, methylol acrylamide, alpha-acetylamine acrylamide and itaconic acid amide. In an example, a 20% solution of a copolymer consisting of 90% acrylonitrile and 10% N-vinyl pyrrolidone in dimethyl formamide and a 20% solution of a copolymer consisting of 91À5% acrylonitrile and 8À5% methyl acrylate in dimethyl formamide are simultaneously extruded into a 50% aqueous dimethyl formamide solution at 40‹ C. to form composite filaments having their components conjugated in side-by-side relationship. The filaments are stretched at a stretch ratio of 4À5 while being washed in boiling water, dried at 100‹ C. and immersed in boiling water to develop crimps.