GB1297730A - - Google Patents

Abstract

1297730 Siloxane-acrylate copolymers DOW CORNING CORP 5 Aug 1971 [8 Sept 1970] 36929/71 Headings C3G and C3T A siloxane-acrylate copolymer comprises: (a) 60-80 p.b.w. of units derived from an acrylate which is acrylic or methylacrylic acid or an aminoacrylate, or a hydrocarbon ester of acrylic acid or methacrylic acid, from 3-5 p.b.w. of the acrylate being acrylic acid, methacrylic acid or mixtures thereof, the acrylate containing sufficient aminoacrylate to neutralize from “-¥ of the acid functionality; and (b) 20-40 p.b.w. of units derived from a siloxane which comprises 45-65 mol. per cent R 2 SiO units and 35-55 mol. per cent RSiO 3 / 2 units, wherein R is a hydrocarbon or substituted hydrocarbon radical, at least one of R containing the structure CH 2 = C =, the ratio of radicals containing the structure CH 2 = C = to silicon atoms in the siloxane being 0À02 : 1 to 0À1 : 1. R can be alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, alkaryl or aralkyl radicals, the cyano and halo derivatives thereof or hydrocarbon radicals containing ether, thioether, ester or thioester linkages. Suitable acrylate esters include methyl-, ethyl-, amyl-, cyclohexyl-, vinyl-, benzyl- and 2-ethylhexyl-acrylate, methyl-, ethyl-, butyl- and hexyl-methacrylate. The aminoacrylates include those of the general formula where R<SP>1</SP> is H or CH 3 , R<SP>11</SP> is H or C 1-8 alkyl, and n=1-8. The copolymers can be prepared by first preparing the siloxane by emulsion polymerization preferably of the organoalkoxysilanes, then adding a free radical catalyst to the siloxane emulsion and then the acrylate monomers, except the aminoacrylates, and copolymerizing. The aminoacrylate is then added and copolymerized with the siloxaneacrylate product. Preferred catalysts are inorganic or organic peroxides or azo-compounds many examples of which are listed. In the examples copolymers are prepared from a siloxane emulsion of siloxane consisting of 60 mol. per cent (CH 3 ) 2 SiO units, 38 mol. per cent C 6 H 5 SiO 3 / 2 units and 2 mol. per cent CH 2 = CHSiO 3 / 2 units, ethyl acrylate, methyl methacrylate, methacrylic acid and tertiary butyl aminoethyl methacrylate using potassium persulphate as catalyst. Latex paint compositions can be made by mixing the siloxaneacrylate emulsions with a pigment dispersion comprising water, an anionio surfactant, TiO 2 , mica, CaCO 3 , aluminium silicate, ethylene glycol, polyethylene glycol, methyl cellulose and a mildew preservative. Uses.-Coating compositions for metals, plastics, wood, concrete, stone, paper, composition board and other cellulosic materials; sealant, adhesive and moulding compositions.