Patent GB-1071464-A (GB)
Title: Heat curable acrylate rubbers and elastomers
IPC: C08F20/54
Filed: 1964-06-30
Abstract: Heat curable elastomeric interpolymers having a second-order transition temperature not greater than 10 DEG  C. contain as essential components (a) 0.2 to 2.5% by weight of units of an N-alkoxy-methyl-acrylamide or N-alkoxy-methyl-methacrylamide wherein the alkoxy group has from 1 to 8 carbon atoms, (b) up to 3.8% by weight of units of a mono-olefinically and terminally unsaturated amide containing at least one H atom on the amide N atom, the unsaturation being in alpha, beta-position to the -CO-moiety of the amide group and the amide molecule, apart from the amide group, consisting only of carbon and hydrogen atoms and (c) units of at least one acrylate ester of the formula CH2=CH-COOR where R is C1- 12 alkyl, beta-cyanoethyl or cyanopropyl, or alkyl methacrylate having 5 to 14 carbon atoms in the alkyl group; the total of components (a) and (b) in the interpolymer not exceeding 4% by weight.  For component (b), the preferred amides are those having the formula <FORM:1071464/C3/1> wherein R2 is hydrogen or C1- 4 alkyl and R3 is hydrogen or C1- 6 alkyl, acrylamide and methacrylamid being most preferred; other amides disclosed are the N-methyl, N-t-butyl, N-ethyl and N-cyclohexyl derivatives of acrylamide. The interpolymers may include minor amounts (generally less than 40% by weight) of units of one or more other monoolefinically unsaturated compounds, e.g. acrylonitrile, methacrylonitrile, vinylidene cyanide, methyl methacrylate, n-butyl methacrylate, cyanomethyl acrylate, alphacyanoethyl acrylate, vinyl chloride, vinylidene chloride, styrene, vinyl ethers, vinyl esters, vinylpyridine, ethylene, propylene, and acrylic, methacrylic, maleic, fumaric, and itaconic acids and alkyl esters thereof.  The interpolymers may be prepared by polymerizing the corresponding monomers in aqueous emulsion or in an organic solvent which dissolves both the monomers and polymer product.  Suitable initiators for polymerization include potassium sodium and ammonium persulphate, hydrogen peroxide, benzoyl peroxide, t-butyl peroxide, caprylyl peroxide, cumene hydroperoxide, potassium perphosphate, diisopropyl percarbonate, azobisisobutyronitrile and the alkylborane-hydroperoxide catalysts described in Specification 865,651, e.g. triisobutyl boron/ hydrogen peroxide; redox systems are also suitable, e.g. p-menthane hydroperoxide/sodium hydrosulphite/sodium formaldehyde sulphoxylate. In emulsion polymerization the pH is generally 7.5 or less; the emulsifier may be nonionic, cationic or, preferably, anionic (many examples are given). The monomers and other components may be added incrementally or continuously to the polymerization mixture, and the reaction is carried to a 90 to 100% conversion.  The interpolymers are generally isolated in the form of a crumb.  Curing of the polymers can be effected simply by heating, but an acidic catalyst may be present, e.g. butadiene sulphone, toluenesulphonic acid, morpholinium toluenesulphonate, salicylic acid, benzoic acid, stearic acid, or an acidic compounding ingredient such as an acidic carbon black or clay filler.  Fillers, pigments and lubricants may be employed together with the curing catalyst, and a polyalkylene glycol is advantageously present.  Reference has been directed by the Comptroller to Specification 792,874.