Patent GB-1195816-A (GB)
Title: The Manufacture of Non-Gelling Soluble Copolymers
IPC: C08F218/08
Filed: 1969-02-11
Abstract: 1,195,816. Ethylene- - vinyl acetate copolymers; phenolic resin compositions. WACKERCHEMIE G.m.b.H. 11 Feb., 1969 [20 Feb., 1968], No. 7244/69. Headings C3P and C3R. [Also in Division B2] Non-gelling, soluble copolymers of ethylene and vinyl acetate having an ethylene content of 30 to 80 mol. per cent are prepared by polymerizing the monomers in aqueous dispersion in the presence of a free radical forming agent, a protective colloid and an emulsifier and in the presence of an aliphatic aldehyde containing 4 to 8 carbon atoms. The copolymer may contain at least one other polymerizable monomer in an amount of up to 10 mol. per cent of the vinyl acetate exemplified by straight-chain and branched vinyl esters, e.g. vinyl propionate, butyrate or laurate, and the vinyl esters of isononanoic acid, isodecanoic acid or a commercially available blend of branched carboxylic acids containing 9 to 11, 13 to 15 or 17 to 19 carbon atoms, and unsaturated mono- and dicarboxylic acids, e.g. acrylic, methacrylic, maleic and fumaric acids, and esters of the acids with mono- and poly-hydric alcohols. The aldehyde, which is exemplified by butyraldehyde, pentylaldehyde, hexylaldehyde, isobutyraldehyde, 2-ethyl hexylaldehyde and diethyl acetaldehyde, amounts to 0À2-3% by weight calculated on the vinyl acetate and may be added gradually during the course of the polymerization. The free radical forming agent preferably forms part of a redox catalyst system comprising an inorganic or organic per-compound, hydrogen and a colloidally distributed noble metal of Group VIII of the Periodic Table. The catalyst may also include ions of iron, copper, nickel, cobalt, chromium, molybdenum, vanadium or cerium. Transparent or opaque tarpaulin or tent material may be obtained by applying to fabrics filler-containing solutions of the copolymers, e.g. in esters, ketones, chlorinated hydrocarbons or aromatic compounds, and after evaporation of the solvent cross-linking the copolymer by the addition of a peroxide. The copolymers may be combined with other condensation and addition polymers including alkylphenol resins, terpenephenol resins, coumarone - indene resins and aldehyde - ketone resins, colophony and pentaerythritol esters of abietic acids, to produce contact and pressuresensitive adhesives. Example 8 is directed to the copolymerization of ethylene and vinyl acetate in aqueous dispersion in the presence of ammonium persulphate, hydrogen, palladium in colloidal solution, methanol, methyl cellulose, alkyl benzenesulphonate and butyraldehyde. The copolymer and a modified phenol resin having an acid number of 100 and a melting range of 140-160 C. were dissolved in a solvent mixture comprising ethyl acetate, toluene and petrol to give a contact adhesive. A copolymer of ethylene, vinyl acetate and fumaric acid gave  a clear solution, free from gelling, in ethyl acetate, toluene and trichloroethylene, and could be cross-linked by the addition of polyfunctional alcohols, epoxides or isocyanates. Comparative experiments disclose the use of acetaldehyde and propionaldehyde in the preparation of the copolymer.