Abstract: A modacrylic fiber comprising a copolymer containing acrylonitrile, at least one of vinyl chloride and vinylidene chloride, and a sulfo group-containing vinyl monomer having a relative reactivity of at least 1 to acrylonitrile, in a specific ratio. The copolymer is prepared by polymerizing the monomers, while adding the sulfo group-containing vinyl monomer to the polymerization system under the following condition:16<Y-X<83wherein X and Y are percentages of the amount of a polymer produced at the time of starting the addition and the amount of a polymer produced at the time of finishing the addition, respectively, based on the amount of the whole polymer to be produced. The fiber has an excellent flame resistance and an excellent devitrification preventing property.

Abstract: A synthetic fiber filament usable for the manufacture of wigs, comprising, in cross section, a center portion, and connected thereto and extending outwardly therefrom three substantially rectangular portions. The novel structure provides unexpectedly good and durable tight curls and bulkness.

Abstract: A method of producing an acrylonitrile copolymer of 40 to 65 weight percent acrylonitrile and mainly vinyl chloride and vinylidene chloride in amounts within the range102.8 <A+B+1.29C<107.4,wherein, A is a mixture of olefinic monomers excluding B and C, in weight percents, mainly comprising acrylonitrile; B is vinyl chloride in weight percents; and C is vinylidene chloride in weight percents; wherein the polymerization is carried out in an aqueous solution of 45 to 65 weight percent dimethyl formamide; and in the presence of 0.2 to 8.0 weight percent of at least one of vinyl benzyl sulfonic acid, derivatives of vinyl benzyl sulfonic acid or salts thereof. The polymer has excellent non-inflammable properties.

Abstract: A method of manufacturing acrylic fibers free from delustering in boiling water, comprises the steps of forming a spinning solution by dissolving in a solvent of acetone, acetonitrile, dimethylformamide and mixtures thereof, (a) a copolymer consisting of (1) 30 - 80% acrylonitril and (2) 70 - 20% vinyl chloride or vinylidenechloride, or (b) a tripolymer consisting of (1), (2) and (3) 3.0% or less by weight of ethylenically unsaturated monomer having hydrophilic groups, and adding one or more compound selected from the group of (1) homopolymer or copolymer of glycidyl methacrylate and (2) specific organic tin compounds, and spinning said spinning solution into a first bath consisting of 60% or less said organic solvent-water and leading said yarn in a 2nd bath consisting of 61 - 85% said organic solvent-water and then in a 3rd and more bath consisting of less than 60% said organic solvent-water and drying, drawing out and annealing said yarn by ordinary methods.

Abstract: A method of manufacturing acrylic fibers free from delustering in boiling water, comprises the steps of forming a spinning solution by dissolving in a solvent of Aceton et al, (a) a copolymer consisting of (1) 30 - 80% acrylonitril and (2) 70 - 20% vinyl chloride or vinylidenechloride, or (b) a tripolymer consisting of (1), (2) and (3) 3.0% or less by weight of ethylenically unsaturated monomer having hydrophilic radicals, and adding one or more compound selected from the group of (1) homopolymer or copolymer of glycidyl methacrylate and (2) specific organic tin compounds, and spinning said spinning solution into a first bath consisting of 60% or less said organic solvent-water and leading said yarn in a 2nd bath consisting of 61 - 85% said organic solvent-water and then in a 3rd and more bath consisting of less than 60% said organic solvent-water and drying, drawing out and annealing said yarn by ordinary methods.