GB1149935A - Siloxane-acrylate co-polymers, and emulsions thereof - Google Patents

Abstract

1,149,935. Siloxane-acrylate copolymers and emulsions thereof. DOW CORNING CORP. 14 Oct., 1966, No. 46043/66. Headings C3G, C3P and C3T. [Also in Division B2] Siloxane-acrylate copolymers comprise 25- 90% by weight of units of an acrylate monomer selected from acrylic or methacrylic acid and esters, nitriles and amides thereof and esters of α-chloroacrylic, α-hydroxymethylacrylic, cyanoacrylic or ethacrylic acid and 10-75% by weight of units of a siloxane consisting of 40- 100 mol per cent of R 2 SiO units and 0-60 mol per cent of RSiO 3 / 2 units wherein each R is a hydrocarbon or substituted hydrocarbon radical. Specified as acrylate components are methyl, ethyl, butyl, amyl, ethylhexyl, cyclohexyl, vinyl, methallyl, benzyl, p-chlorobenzyl, hydroxyethyl, hydroxypropyl and perfluoroethyl esters of acrylic acid, methyl α-chloroacrylate, ethyl α-hydroxymethyl-acrylate, ethyl cyanaoacrylate, methyl or ethyl methacrylate, hydroxyethyl or hydroxypropyl methacrylate, methyl ethacrylate, ethylene glycol diacrylate, glyceryl triacrylate and diethylene glycol dimethacrylate. In the siloxane component(s), R can be alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, alkaryl or aralkyl or a substituted derivative thereof. R is preferably selected from methyl, ethyl, vinyl, allyl, and 3,3,3-trifluoropropyl, and the number of R radicals that are vinylic in the siloxane is preferably such that the ratio of vinylic radicals to Si atoms is from 0À02: 1 1 to 0À3: 1. In examples the following methods of preparing the copolymers are employed: (a) a siloxane containing vinylic groups is prepared in emulsion and then the product is emulsion copolymerized with acrylate monomers; (b) acrylate monomers (including a hydroxyalkyl acrylate) are emulsion copolymerized with nonvinylic silanes which include hydroxy or alkoxy groups; (c) a modification of (b) wherein the acrylate monomers are copolymerized in the presence of a preformed siloxane copolymer containing OH or alkoxy groups and also, in some cases, vinylic groups; (d) acrylate monomers are copolymerized in solution in an organic solvent and the product (containing hydroxyalkyl groups) is reacted with a siloxane or a mixture of silanes containing methoxy groups; (e) acrylate monomers are emulsion copolymerized in the presence of a siloxane containing mercaptopropyl groups (the siloxane being prepared by reacting a preformed siloxane emulsion with HS(CH2) 3 Si(OCH 3 ) 3 in the presence of dodecylbenzenesulphonic acid). In all cases (a) to (e) the acrylates are polymerized with a catalyst selected from potassium or ammonium persulphate, hydrogen peroxide, azodiisobutyronitrile, benzoyl peroxide, t-butyl hydroperoxide and a mixture of cumene hydroperoxide or benzoyl peroxide with t-dodecyl mercaptan. The emulsions and solutions of the acrylatesiloxane copolymers are useful as adhesives and as coating compositions. They can be formulated into paints by inclusion of pigments such as titanium dioxide, mica, calcium carbonate, aluminium silicate, yellow iron oxide and phthalocyanine green, and additional components such as ethylene glycol, polyethylene glycol, methyl cellulose, di(phenyl mercuric)dodecyl succinate, a defoaming agent (e.g. a silicone) and hexamethoxymethylmelamine. Coatings or films containing the copolymers can be cured by heating.