Two-stage emulsion polymerization process

A conjugated diolefin of 4 to 6 carbon atoms with, if desired, up to 5 per cent by weight of at least one other monomer copolymerizable therewith, is partially polymerized in emulsion in the presence of an oxygen-liberating catalyst until 5-80 per cent of the initial monomer is converted into a polymer, at least one other monomer originally present therein in amount between 0 and 5 per cent by weight is added in one step or in increments and the polymerization continued until at least 50 per cent of the monomers now present are polymerized. Specified diolefins are butadiene, piperylene, isoprene, 2,3-dimethylbutadiene, 2-methylpentadiene, n-hexadiene, cyclopentadiene, methylcyclopentadiene, and cyclohexadiene. Specified other monomers are acrylonitrile, methacrylonitrile, ethacrylonitrile, chloracrylonitrile, styrene, vinyl chloride, vinylidene chloride, methyl acrylate, methyl methacrylate, chloroprene, vinyl isobutyl ether, and vinyl ketones. Emulsifying agents such as an alkali soap of caprylic, carnaubic, lauric or mixed coconut oil acids, ammonium, sodium or potassium oleate or stearate, sodium lauryl sulphate, sodium tetra-isobutylene sulphonate, aromatic alkyl sulphonate salts and the sodium salt of a formaldehyde condensation product of naphthalene sulphonic acids may be used. The polymerization temperature may vary from -20 DEG to 60 DEG C. and at the low temperatures an anti-freeze agent such as methanol, ethanol, ethylene glycol, propylene glycol or glycerine may be present. Specified catalysts are hydrogen peroxide, benzoyl peroxide, cumene hydroperoxide, tertiary butyl hydroperoxide, potassium persulphate or other alkali persulphates or perborates or the corresponding ammonium salts or a Redox catalyst. A polymerization modifier such as hexyl, dodecyl, lauryl, tetradecyl or octadecyl mercaptan, or diisopropyl dixanthogendisulphide may be present as may also activators such as potassium ferricyanide, tolyl diazobeta-naphthol, solution of ferric pyrophosphate or ferrous sulphate and sodium pyrophosphate in dextrose, fructose, invertose, polyglycols or diacetone alcohols. The preparation of terpolymers is described. The resulting polymers may be stabilized with hydroquinone and phenyl betanaphthylamine and coagulated with brine and dilute acetic acid or may be vulcanized using such compounds as mercaptobenzothiazole, tetramethyl thiuram disulphide, the carbamates, diphenyl guanidine, and quinone dioxime compounds together with channel black, zinc