Patent GB-1122594-A (GB)
Title: Process for making fire retardant polymethyl methacrylate compositions
Inventor: JUKES ALAN WILLIAM
IPC: C08F20/14
Filed: 1965-06-17
Abstract: Flame-retardant polymeric compositions comprise (1) a polymer selected from (a) methyl methacrylate homopolymer, (b) a copolymer of methyl methacrylate with up to 10% by weight of the methacrylate of an ethylenically unsaturated carboxylic acid or anhydride, (c) a copolymer of methyl methacrylate and a monoethylenically unsaturated compound other than a carboxylic acid or anhydride, and (d) a co-polymer as in (c) but which is additionally derived from up to 10%, by weight of the methacrylate and mono-ethylenically unsaturated compound, of an ethylenically unsaturated carboxylic acid or anhydride; (2) from 1-30% by weight of said polymer of a trialkyl orthophosphate in which the alkyl radicals contain 1 to 8 carbon atoms and may optionally be substituted with one or more halogen atoms; and (3) from 1-30% by weight of said polymer of a compound of the formula <FORM:1122594/C3/1> where n is a whole number from 0 to 2; m is a whole number from 0 to 100 when n is 2, and 0 when n is less than 2; Y is a ­P, ­P =O or ­P =S group; each R is a hydrocarbyl, halohydrocarbyl, alkoxyhydrocarbyl, or (hydrocarbyloxy)halohydrocarbyl radical of 1-12 carbon atoms, or such a radical linked to the P atom of Y by an -O- or -S- group, and when n = 2 the two R's together may represent an -O-hydrocarbylene-O- or -O-halohydrocarbylene-O-radical which is free of aliphatic unsaturation and which contains 2-10 carbon atoms; R111 is a hydrocarbyl, halohydrocarbyl, alkoxy halohydrocarbyl or (hydrocarbyloxy) halohydrocarbyl radical of 1-12 carbon atoms, or such a radical linked to the indicated P atom by an -O- or -S-group; Z is hydrogen or a hydrocarbyl, halohydrocarbyl, carboalkoxyhydrocarbyl, alkylthiohydrocarbyl, alkoxyhydrocarbyl or cyanohydrocarbyl radical of 1-17 carbon atoms when n is 2, and from 1-10 carbon atoms when n is less than 2, or a furyl or thienyl radical; and R1 and R11 are each an alkyl, haloalkyl, aryl, haloaryl, alkoxy, haloalkoxy or (hydrocarbyloxy)-haloalkoxy radical of 1-12 carbon atoms; and wherein the Z radicals, when more than one in number, are the same and the R, R1, R11 and R111 radicals respectively are the same or different.  Suitable non-acidic comonomer components of the methyl methacrylate copolymers include alkyl or cycloalkyl acrylates or methacrylates, styrene and its halo- and alkyl-derivatives (e.g. a -chloro- or a -methylstyrene), (meth)acrylonitrile and (meth)acrylamide, maleimide, and N-alkyl, N-aryl or N-halophenylmaleimides. Acidic comonomer components specified are acrylic, methacrylic, maleic and itaconic acids and, also, maleic anhydride (Example XVI).  The copolymer may also be derived from a minor proportion of a polyunsaturated monomer, e.g. glycol dimethacrylate, divinyl benzene, vinyl methacrylate, methylene dimethacrylate, allyl methacrylate, diallyl phthalate, diallyl maleate, allyl acrylate or methallyl acrylate.  The compositions may be prepared by mixing together compounds (1), (2) and (3) and extruding the product; alternatively, the monomer component(s) of (1) can be polymerized in the presence of compounds (2) and (3).  Such polymerization can be effected in bulk, emulsion, solution or suspension and can be initiated by heating with azodiisobutyronitrile, lauroyl peroxide or benzoyl peroxide, or by exposure to light in the presence of benzoin, acetoin, butyroin or diacetyl; monomer/polymer syrups can be polymerized in a mould. A mercaptan may be present during polymerization. Additives may be incorporated in the compositions or polymerization mixtures, e.g. dyestuffs, U.V. absorbers, heat and colour stabilizers, plasticizers, mica, and polystyrene (to produce an opalescent effect).  The compositions can be formed into sheets, films and other articles, e.g. lighting fitting covers.