GB873948A - Suspension polymerisation process - Google Patents

Abstract

Water-insoluble ethylenically unsaturated compounds capable of radical-addition polymerization by a suspension polymerization process, are polymerized in aqueous suspension in the presence as suspension stabilizer of a minor amount of a polyalkylene oxide compound having a molecular weight of at least 20,000. The polyalkylene oxide compound may be a polyalkylene ether glycol or an ether or ester thereof, or a condensation product of an alkylene oxide with a polyhydroxy nucleating agent such as hydroquinone, resorcinol, glycerol, pyrogallol or pentaerythritol; and are preferably derived by the homo- or copolymerization of styrene oxide, ethylene oxide, 1, 2-propylene oxide, 1, 3-propylene oxide, tetrahydrofuran and 1, 2-butylene oxide. The unsaturated compound may be styrene, vinyl toluene, divinyl benzene, a -methyl styrene, nuclear halogenated styrene, butadiene, isoprene, chloroprene, 2, 3-dimethyl butadiene, piperylene, acrylonitrile, methyl methacrylate, ethyl acrylate, vinyl chloride, vinylidene chloride and mixtures thereof. Graft polymers may be prepared by polymerizing the compounds in the presence of preformed polymers, e.g. polybutadiene, polyisoprene, rubbery butadienestyrene and butadiene-acrylonitrile copolymers, and the stereospecific polydienes such as cis-1, 4-polyisoprene or cis- or trans-1, 4-polybutadiene, or the elastomeric ethylene-propylene copolymers. The stabilizer may be used with a surface active agent which is present in amount insufficient to give rise to an emulsion polymerization process. The surface active agent may be anionic, cationic or non-ionic, e.g. alkali metal fatty acid and rosin acid soaps; alkali metal alkylaryl sulphonates, alkyl sulsulphates and alkyl sulphonates; quaternary ammonium compounds; and ethylene oxide condensates with phenols and fatty acids. Catalysts, e.g. benzoyl peroxide, lauryl peroxide, tert.-butyl perbenzoate, cumyl hydroperoxide, azo-bis-isobutyronitrile and azo-bis-cyclohexane carbonitrile; chain transfer agents, e.g. tert.-dodecyl mercaptan; lubricants, e.g. butyl stearate and glycerol monostearate; sequestering agents; antioxidants and fillers may also be present. The monomer may be partially prepolymerized in bulk, e.g. by heat, ultra-violet light or ionizing radiation. Many suitable materials are listed and examples describe the partial prepolymerization of styrene containing GRS rubber, tris (nonylphenyl) phosphite and butyl stearate, followed by the suspension polymerization thereof in the presence of (1, 2, 3, 5, 6, 7 and 8) polyethylene oxides of molecular weight 400,000; (9) polyethylene oxides of molecular weights 400,000, 100,000 and 4,000,000; (11) polyethylene oxides of molecular weight 400,000 together with sodium dodecylbenzene sulphonate; (12) polyethylene oxides of molecular weight 400,000, sodium dodecylbenzene sulphonate and potassium or sodium chloride; (4) the polymerization of styrene in the presence of polyethylene oxide of molecular weight 1,800,000; and (10) the polymerization of methyl methacrylate in the presence of a polyethylene oxide of molecular weight 400,000. Polyalkylene oxides of molecular weight greater than 20,000 may be prepared by polymerizing styrene oxide and the alkylene oxides listed above in the presence of alkoxides and aroxides of metals of Group II-V of the Periodic Table, metal alkyls and metal alkyl halides of Group II and III metals, Friedel-Crafts catalyst complexes such as complexes of the alkylene oxide with ferric or stannic chloride and synergistic combinations of such catalysts. Examples describe the use of polyethylene oxides of molecular weights 100,000, 400,000, 1,800,000 and 4,000,000.