GB837704A - Improvements in or relating to thermoplastic mixtures of copolymers - Google Patents

Abstract

A thermoplastic composition comprises (1) an elastomeric terpolymer of butadiene or homologue or derivative thereof and acrylonitrile with a minor proportion of a further ethylenically-unsaturated monomer to which, in the polymer, is attached a self-cross-linking group and optionally divinyl benzene, glycol diacrylate or vinyl chloride; and (2) a thermoplastic copolymer of 95-55 parts by weight of styrene or a nuclear-substituted derivative thereof and 5-45 parts of acrylonitrile; the terpolymer (1) being present as 10 to 75% by weight of the composition and part of the copolymer (2) optionally being replaced by polyvinyl chloride or a copolymer of vinyl chloride with vinylidene chloride or vinyl acetate. The elastomeric terpolymer may be made by copolymerizing butadiene or isoprene, acrylonitrile, and an unsaturated monomer carrying the requisite self-cross-linking groups by which is to be understood groups which effect crosslinking when heated to 100-220 DEG C. and which may be carbonyl groups such as carboxyl, carbonamide and aldehyde groups; methylol and methylol ether groups; dioxolane groups; ureido groups; and groups of the formula <FORM:0837704/IV (a)/1> where R4 and R5 each stand for a hydrocarbon residue which may be bound to the carbonyl group through an oxygen atom. A large number of general classes of compounds are referred to and the following specific examples: acrylic acid, a -chloromethacrylic acid, methacrylic acid, crotonic acid, sorbinic acid, cinnamic acid, mono-alkyl esters of acrylamide, methacrylamide, acrolein, methacrolein, alkyl ethers of the methylol derivatives of acrylamide, isopropylidene-glyceryl acrylate and methacrylate, methylene glyceryl acrylate and methacrylate, b -ureidoethyl acrylate and methacrylate, b -ureidoethyl vinyl ether, 3-ureido-n-propyl vinyl ether, b -ureido-isobutyl vinyl ether, N-(2-vinyl-oxyethyl) - N1 - cyclohexyl urea, N - (2 - vinyl-oxyethyl)-N1-ethyl urea, and the methylene derivatives of malonic acid esters, ethyl acetoacetate and acetyl acetone. The self-cross-linking group can also be introduced into the copolymer by reacting polymers containing copolymers containing carbonamide groups with formaldehyde, if desired in the presence of an alcohol to introduce methylol or methylol ether groups. These elastomeric copolymers preferably contain 5-45 wt. per cent of acrylonitrile and 0.1-20 wt. per cent of monomers with self-cross-linking groups, the rest being butadiene; these copolymers are converted into an insoluble gel by heating for a short time. They are prepared by standard emulsion polymerization. Additional cross-linking monomers, such as divinyl benzene and glycol diacrylate, and additional monomers such as vinyl chloride, may also be copolymerized. The thermoplastic copolymer may also be prepared by emulsion polymerization. Suitable styrene derivatives are 2-chloro-, 4-chloro- and 2,4-dichloro-styrenes. The blending of the copolymers is carried out by mixing the latices of the copolymers as obtained by emulsion polymerization and the mixture coagulated by known methods, washed, dried, and cross-linked by heating to 100-220 DEG C. Aqueous emulsions or dispersions of pigments, stabilizers and plasticizers may be added to the mixed latices before coagulation, and in the examples, titanium dioxide is added to the blends. Alternatively the elastomeric copolymer may be cross-linked and thereafter mixed with the thermoplastic copolymer. Numerous examples are given.