Patent GB-896955-A (GB)
Title: Composite synthetic textile fibres
IPC: D01F8/04
Filed: 1960-03-15
Abstract: <PICT:0896955/IV (a)/1> <PICT:0896955/IV (a)/2> <PICT:0896955/IV (a)/3> <PICT:0896955/IV (a)/4> A composite filament comprises at least tw hydrophobic polymeric components eccentrically disposed towards each other, at least one of the components containing mixed therewith a polymer having a water absorption of at least 6%, the composite filament being crimpable from the straight state upon shrinkage and having crimp reversibility upon treatment with and subsequent removal of water. Preferably, each of the components comprises a polyamide or an acrylonitrile polymer having at least 80% combined acrylonitrile, but polyesters, polyester amides, polyurethanes, polyhydrocarbons, polyethers and polymers of vinyl chloride, vinylidene chloride and vinyl acetate are also suitable, as are copolymers of the foregoing, especially copolymers of acrylonitrile with ethylenically unsaturated sulphonic acids, e.g. methallyl sulphonic acid.  The waterabsorbing polymer may be poly-N-vinylmethylformamide, poly-N-vinylpyrrolidone, or zein. Other suitable water-absorbing polymers include N,N-dimethylacrylamide, bis(ethyl)vinyl phosphonate, N-methyl-N-vinyl acetamide, alkyl vinyl phosphites, phosphine oxide and isoprene, N-acrylylmorpholine, N-acrylyl-piperidine, N-acrylyl thiomorpholine, N-vinyl caprolactam, N-vinyl piperidene, cyanoethylated cellulose, and graft copolymers containing N-acrylyl and N-methacrylyl substituted nitrogen heterocyclic compounds.  The water-absorbing polymer may be present in an amount such that the product of its percentage water absorption multiplied by the fraction it comprises of the mixed polymer component is at least 1,0, and the blended component should preferably contain not more than about 50% by weight of the water-absorbent polymer.  In the composite filament, the components may be disposed in side-by-side relationship as shown, or in the form of a core completely and eccentrically surrounded by a sheath.  The filaments may be made by spinning together the said components, at least one of which is fibre-forming, so that the components form over the cross-section of the single composite filaments two or more distinct zones which extend through the entire length of the filament in eccentric fashion, whereby only one, or alternatively, part of or all the components form the surface of the single composite filament. Dry-spinning methods are described.  Apparatus as shown comprises a spinneret plate 2 containing a circle of orifices 3, held against back plate 1 by rings 12, 14 and bolt 13.  A fine-mesh screen 4 occupies the space between the plates 1 and 2.  Back plate 1 contains two annular chambers 8 and 9 which receive different spinning compositions, and which connect via lead holes 10 and 11 with annular spaces 6 and 7, which latter are separated by wall 5.  Wall 5, being disposed above orifices 3 and spaced from plate 2 by screen 4, permits free and contiguous passage of the spinning compositions from annular spaces 6 and 7 via screen 4 through orifices 3. Typical filaments so made are shown.  The composite filaments may be drawn at least 1,5 times and preferably 2-8 times the original length.  In Example (1A) a 23% solution of polyacrylonitrile in N,N-dimethyl formamide is spun simultaneously with a 23% solution of a blend of 90% polyacrylonitrile and 10% poly-N-vinyl pyrrolidone in N,N-dimethyl formamide at 110 DEG C. into a spinning cell, the walls of which are maintained at 170 DEG C., and through which passes a concurrent flow of carbon dioxide-nitrogen mixture at 320 DEG C.  The yarn is wound up at 200 yards per minute and subsequently drawn 4,5 times in water at 95 DEG -98 DEG C., which simultaneously extracts the residual dimethyl formamide.  The resulting yarn on boiling in water develops 14,2 crimps per inch and has a denier per filament of 3,3, an equilibrium crimp reversibility of 20,8%, and a crimp reversibility of 0,46 and 1,09 t.p.i. at 25 DEG C. and 90 DEG C. respectively, and the crimped fibre displays 321% recovery from compression on steaming.  Further examples describe the spinning of (1B) a dimethylformamide solution of a copolymer 90% acrylonitrile and 10% N-vinyl pyrrolidone, together with a polyacrylonitrile solution; (2) dimethylformamide solutions of (a) a copolymer of 98% acrylonitrile and 2% styrene sulphonic acid, with (b) a 90/10 mixture of this copolymer and poly-N-vinyl pyrrolidone; (3) (A) dimethylformamide solutions of (a) a 90/10 polyacrylonitrile/poly-N-vinyl methylformamide mixture and (b) polyacrylonitrile; 3(B) as (A) but replacing the mixture (a) with a copolymer of the corresponding monomers; (4) as (2), replacing the poly-N-vinyl pyrrolidone with poly-N-vinyl methylformamide; (5) a dimethylformamide solution of (a) a copolymer of 94% acrylonitrile and 6% methyl acrylate is spun together with (b) a mixture of 80% of the above copolymer and 20% of zein, in the same solvent; (7) as 1(A), replacing the poly-N-vinyl pyrrolidone with poly-N,N-dimethylacrylamide; (8) a solution (a) of a condensation product of m-phenylene diamine and isophthaloyl chloride in N,N-dimethylacetamide is spun together with (b) a portion of solution (a) containing also 15% of the total polymer weight of poly-N-vinyl pyrrolidone.  Specifications 461,236, 461,237, 568,881, 578,079, 597,368, 830,441, U.S.A.  Specifications 2,071,250, 2,130,948, 2,190,770, 2,527,300, 2,601,256, 2,731,446 and 2,798,061 are referred to.