Patent GB-587403-A (GB)
Title: Improvements in the manufacture of compositions and textile articles having a basis of vinyl polymers
IPC: D01F6/08
Filed: 1944-05-04
Abstract: Artificial textile fibres or filaments having a tenacity of at least 2 grams per denier and which are dimensionally stable at 100 DEG  C. are composed of a vinyl resin obtainable by the conjoint polymerization of a vinyl halide and acrylonitrile, which resin contains between 45 and 80 per cent of the halide in the co-polymer, has a specific viscosity (as defined below) between 0.2 and 0.6 at 20 DEG  C., and is completely dispersible in acetone at about 50 DEG  C. The specific viscosity of the resin is determined with an Ostwald viscosimeter and is numerically equal to the ratio of the viscosity of a solution of 0.1 gram of the resin in 50 c.c. of acetonyl acetone to the viscosity of the acetonyl acetone, minus one.  The filaments may be prepared by spinning a dispersion of the above resin, twisting the filaments to form a yarn, stretching the yarn at least 200 per cent while exposed to a temperature between 110 and 250 DEG  C., and stabilizing the stretched yarn by heating it to a temperature between 100 and 150 DEG  C., preferably while in an untensioned condition. After removal of residual solvent, the unstretched yarn may be stretched between 200 and 1100 per cent in steam at 120 to 140 DEG C.  When dry heat is used higher temperatures, e.g., temperatures up to 250 DEG  C. may be employed.  The vinyl halide-acrylonitrile copolymers may be produced by conjointly polymerizing the vinyl halide and the acrylonitrile in the form of an emulsion with water, preferably at 35 to 55 DEG  C. in the presence of catalysts, e.g. alkali metal persulphates, hydrogen peroxide, and benzoyl chloride. Pressures of 20 to 110 pounds per square inch are convenient.  The resin may be dissolved in acetone for spinning and a small quantity of a stabilizer such as organo-metallic tin and lead salts of carboxylic acids may be added.  In wet spinning, the spinning bath may consist of water containing up to 25 per cent of acetone, and if desired, a preliminary stretch of about 150 per cent may be applied between the godet and the take-up bobbin.  In dry spinning, a solution of the resin in acetone, acetonyl acetone, cyclohexanone or nitroethane is spun into air, e.g. at 85 DEG  C.  In example I, a liquid containing water, vinyl chloride, acrylonitrile, potassium persulphate and sodium di - (2 - ethylhexyl) - sulpho-succinate is heated to 40 DEG  C. for 50 hours and after the initiation of the polymerization acrylonitrile is added in amount sufficient to maintain a ratio of monomeric vinyl chloride to monomeric acrylonitrile of approximately 90 : 10.  The resin is coagulated by adding acetone, washed, dissolved in acetone and stabilized by adding dibutyl tin laurate.  The solution is spun into air at 120 DEG  C., and the yarn is twisted, and stretched 1104 per cent during passage through steam at 127 DEG  C. The yarn is then skeined and stabilized by immersion in boiling water for one hour.  In example II a solution of the same polymer is spun into water and stretched 150 per cent during take-up.  The filaments are then aged in water at 65 DEG  C., twisted, and stretched 800 per cent in steam at 128 DEG  C.  The yarn is finally stabilized by immersion in boiling water.  In example III, a similar polymer is dispersed in acetone, spun into water and stretched during take-up by 150 per cent.  The filaments are then soaked in water, twisted, stretched 505 per cent in steam at 130 DEG C. and finally stabilized in boiling water.  In example IV, an acetone solution of the conjoint polymerization product is dry spun, stretched, twisted and stabilized as in the first example.  The fibres and filaments may be used in the manufacture of filter fabrics, fishing lines and nets, sutures, bolting cloth, pipe coverings, electrical insulation, protective clothing, glider fabrics, screen print fabrics, tow ropes, parachute shrouds and cords, bathing suits, hosiery and velvet.  Specification 518,555 is referred to.