GB838978A - A process for the preparation and processing of a plastic polymerisable moulding material - Google Patents

Abstract

Polymerizable moulding compositions may be prepared and processed by processes comprising producing at room temperature at least two granulates each comprising 50 to 90 parts by weight of one or more pulverulent polymers which are at least capable of swelling in monomeric liquids and 10 to 50 parts of one or more monomeric liquids, one of said granulates containing at least one polymerization initiator and another of said granulates containing at least one polymerization accelerator, by mechanically mixing the pulverulent polymers with the monomeric liquids containing the initiator and accelerator respectively, mechanically mixing said granulates to a homogeneous, air-free cuttable mixture and then moulding said mixture with heat and under pressure and hardening it by polymerization. The polymers may be homopolymers, copolymers or grafted polymers of polymerizable ethylenically unsaturated compounds, e.g. acids, esters, amides, nitriles, vinyl aromatic hydrocarbons and vinyl heterocyclic compounds; the monomeric liquids may be liquid unsaturated compounds as listed above and may contain cross-linking comonomers or solid or gaseous monomers in solution. The initiators may be organic peroxy compounds and the accelerators, amines, organic sulphides, mercaptans, sulphinic acids, hydrazine derivatives, sugars, aldehydes, and metal compounds. Many suitable polymers, monomers, initiators and accelerators are listed and examples describe the use of (1) and (2) granulates of vinyl chloride-methyl acrylate polymer and methyl methacrylate containing dibenzoyl peroxide and N,N - dimethyl - paratoluidine; corresponding granulates using (3) vinyl chloridemethyl methacrylate copolymer; (4) vinyl chloride-acrylonitrile copolymer; (5) vinylidene chloride - vinyl chloride - methyl acrylate terpolymer; (6) polyvinyl alcohol, polymethacrylic acid or polystyrene with methyl methacrylate grafted on by solution polymerization and (7) vinyl chloride-vinyl acetate copolymer; as above using as the liquid monomer (8) methacrylic acid and methyl methacrylate, (9) methacrylamide and methyl methacrylate, (10) solutions of vinyl chloride in methyl methacrylate, (11) incorporating ethylene glycol dimethacrylate in the monomeric liquid as cross-linking agent; using (12) diacetyl peroxide as initiator and (13) dimethylaniline as accelerator; using a third granulate comprising (14) vinyl chloridemethyl methacrylate copolymer and tetraethylene glycol dimethacrylate, (15) vinyl chloride-methyl methacrylate copolymer, methacrylic acid, phosphoric acid and aluminium oxide; and (16) with dioctyl phthalate. The compositions may also comprise fillers, e.g. calcium carbonate, talc, silica, asbestos, metal and metal oxide powders, glass fibres, cellulose esters and ethers, linozyn, soot, shellac, melamine and phenol resins, cotton, linen and synthetic fibres; e.g. of cellulose derivatives, polyacrylonitrile and polyamides; dyestuffs and stabilizers against heat and light, e.g. zinc stearate. The granulates may be stored, prior to moulding, in airtight tins or further processed into rolled sheets, extruded ropes or fillable or kneadable compositions. After mixing they may be moulded by injection moulding or pressure spraying, may be pressed into sheets between metal or glass plates, and moulded to form gramophone records.