GB1097584A - Sheet - Google Patents

Abstract

Copolymers comprising at least 25 weight per cent of units of an N-substituted unsaturated amide of formula <FORM:1097584/C3/1> where R and R1 are hydrogen or C1- 3 alkyl and R11 is hydroxyl, C1- 3 alkoxy or dialkylamino, the balance of the copolymer being units of one or more ethylenically unsaturated monomers other than unsaturated amides may be prepared by copolymerizing the monomers in aqueous media in the presence of a catalyst. Preferred amides are reaction products of formaldehyde with acrylamide, methacrylamide or dialkylamine. Specified are acrylonitrile, vinyl acetate, methyl acrylate, methyl methacrylate and styrene, optionally together with with sufficient acid, e.g. acrylic, methacrylic, itaconic or maleic acid, to render the alkali metal, ammonium and amine salts of the copolymers water-soluble. The copolymers may be spun into fibres which may be felted or netted, or used for impregnating fabrics and felts; and may be cross-linked by heating. In Examples (1 and 2) acrylonitrile, acrylic acid and N-methylol acrylamide are copolymerized in water/isopropanol in the presence of azodiisobutyronitrile, and (3) methyl acrylate and N-methylol acrylamide are copolymerized in water in the presence of azo-g -cyanovaleric acid, and polymer solution blended with a butadiene/acrylonitrile elastomer latex and magnesium chloride solution.ALSO:Flexible sheets may be prepared by bonding fibres with a copolymer comprising at least 25 weight per cent of units of an N-substituted unsaturated amide of formula <FORM:1097584/D1-D2/1> where R is hydrogen, alkyl or substituted alkyl, R1 is hydrogen or alkyl containing up to 3 carbon atoms and R11 is hydroxyl, alkoxy containing up to 3 carbon atoms or dialkylamino, the balance of units being other than those of unsaturated amides. Fabrics may be impregnated with solutions of the copolymers, e.g. in water, aqueous calcium chloride and sodium thiocyanate solutions, alcohols and ketones, and the polymers precipitated, e.g. by acid. The sheets or fabrics may be given a permanent set by wetting, shaping and drying in the desired shape. In examples (2) a disc of viscose rayon fibre wadding is impregnated with a water/isopropanol solution of a copolymer of acrylonitrile and N-methylol acrylamide, washed with dilute sulphuric acid and water and dried at room temperature and hot pressed, and (3) a needled crimped nylon felt is impregnated with a mixture of a butadiene/acrylonitrile elastomer latex, magnesium chloride solution and an aqueous solution of a methyl acrylate / N-methylol acrylamide copolymer, dried in air and compressed at 800 p.s.i. at 160 DEG C. for 20 seconds.ALSO:Flexible sheet materials incorporating a copolymer comprising at least 25 per cent. by weight of units of an N-substituted unsaturated amide of formula <FORM:1097584/B1-B2/1> where R is hydrogen, alkyl or substituted alkyl, R1 is hydrogen or alkyl containing up to 3 carbon atoms and R11 is hydroxyl, alkoxy containing up to 3 carbon atoms or dialkyl amino, the balance of the copolymer being units of one or more ethylenically unsaturated monomers other than unsaturated amides, may be prepared by casting a coherent sheet of the copolymer on a fabric or a mat or web of unwoven fibres. The copolymer may be applied from solutions in water, aqueous calcium chloride or sodium thiocyanate solutions, lower alcohols or ketones.