GB1100386A - Production of acrylic coatings - Google Patents

Abstract

Coated substrates are obtained by applying to the surface of the substrate, e.g. synthetic fabric, metal sheet or wood, a solution comprising an admixture of a polyisocyanate and a copolymer in an inert organic solvent, and curing and/or drying the coating applied; the copolymer used comprising 50-99% by weight of at least one ester of acrylic acid and a C1-C8 alkanol, 1-35% by weight of at least one monomer containing at least one hydroxyl group, at least 50% by weight of this hydroxy-component consisting of at least one bicyclo-[2,2,1]-heptene-(2) derivative having at least one hydroxyl group in the ring or side chains, and 0-25% by weight of at least one further comonomer. The side chains of the bicycloheptene derivative may form another ring system as, for example, in N-b -hydroxyethyl-bicycloheptene - 5,6 - dicarboxylic imide. Suitable hydroxy monomers, additional to the bicycloheptene compounds, include allyl alcohol and diol monoacrylates; optional comonomers include acrylonitrile, styrene and its derivatives, vinyl carbazole, vinyl chloride, vinylidene chloride, vinyl esters, e.g. vinyl acetate, and possibly small amounts of carboxylic acid or amino monomers. Aromatic polyisocyanates are the preferred polyisocyanates. Suitable solvents include ethyl acetate, 2-ethoxyethyl acetate, acetone, tetrahydrofurane, dibutyl ether, toluene and xylene. The coatings may be cured at room or elevated temperature; curing can be accelerated by using tertiary amines, bismuth or lead salts, or tin compounds as catalyst. The coating solution may be pigmented, e.g. with rutile titanium dioxide. Examples illustrate the preparation of the copolymers by solution polymerization in the presence of azodiisobutyronitrile initiator and also, in some cases, diisopropyl xanthic disulphide as chain regulator, part of the reactants being added during the course of polymerization.ALSO:Coated substrates are obtained by applying to the surface of the substrate a solution comprising an admixture of a polyisocyanate and a copolymer in an inert organic solvent, and curing and/or drying the coating applied; the copolymer used comprising 50-99% by weight of at least one ester of acrylic acid and a C1-C8 alkanol, 1-35% by weight of at least one monomer containing at least one hydroxyl group, at least 50% of this hydroxy-component consisting of at least one bicyclo-[2,2,1]-heptene-(2) derivative having at least one hydroxyl group in the ring or side chains (which may form another ring system), and 0-25% by weight of at least one further comonomer. Other hydroxy components of the copolymer include allyl alcohol and diol monoacrylates; further comonomers specified are acrylonitrile, styrene and its derivatives, vinyl carbazole, vinyl chloride, vinylidene chloride, vinyl esters, e.g. vinyl acetate, and small amounts of carboxylic acid or amino monomers. Aromatic polyisocyanates are the preferred polyisocyanates. Suitable solvents include ethyl acetate, thoxy-ethyl acetate, acetone, tetrahydrofurane, dibutyl ether, toluene and xylene. A pigment, e.g. titanium dioxide, may be included in the solution. The solutions may be applied by, e.g. spraying, brushing or knife coating to substrates such as synthetic fibre fabrics, e.g. knitted polyamide fabrics, wood, and sheet metal, e.g. iron. The coatings can be cured at room or elevated temperature; curing can be accelerated by using tertiary amines, bismuth or lead salts, or tin compounds as catalyst.