GB874576A - Process for the production of spheroidally shaped polymer particles - Google Patents

Abstract

Spheroidal solid polymer particles, e.g. beads, are made by the suspension polymerization of ethylenically unsaturated water-insoluble monomers in aqueous medium in the presence of a colloidally dispersed water-swollen but waterinsoluble sulphonated vinylidene aromatic polymer, e.g. homopolymers of styrene, alpha- and ar-methyl styrenes, ar-dimethyl, -ethyl and -chlorostyrenes, isopropenyl toluenes and vinyl naphthalenes and copolymers of such compounds with each other or with other compounds such as isobutylene, butadiene, acrylonitrile and C1-C12 alkyl acrylates and methacrylates. The sulphonated polymer may be used in free acid or salt form. The polymerizable monomer may be one of the above-mentioned monomers, N-vinyl carbazole, vinylidene chloride or divinyl benzene which may be polymerized alone or in admixture with one another, e.g. a mixture of styrene and divinyl benzene. Polymerization may be initiated by compounds such as benzoyl, di-tertbutyl and cumyl peroxides and azobisisobutyronitrile. The aqueous medium may contain a polymerization inhibitor, e.g. potassium di-chromate, to prevent the formation of colloidal polymer, and may have an alkaline or acid pH, e.g. pH6. The monomeric material may contain 1%-15% of a volatile organic liquid, e.g. C4-C7 hydrocarbon, to provide products which may be expanded by heating to a temperature above the boiling point of the liquid and above the softening point of the polymer. The Specification describes also the sulphonation of an m-vinyl toluene-p-vinyl toluene copolymer with sulphuric acid and the conversion of the resulting product to ammonium salt form. Specifications 775,409 and 784,028 are referred to.ALSO:Foamed polymeric material is made by the suspension polymerization of a mixture ethylenically unsaturated water-insoluble monomeric material and 1 to 15% of a volatile organic liquid in which the resulting polymer is only sparingly soluble, the polymerization being carried out in an aqueous medium containing a colloidally dispersed water-swollen but water-insoluble vinylidene aromatic polymer (see Group IV(a)) to yield spheroidal polymer particles which are expanded by heating to a temperature above the boiling point of the liquid and above the softening point of the polymer. Monomers specified are styrene, ar-methyl and-ethyl stirenes, ar-dimethylstyrenes, isopropenyltoluenes, ar-methoxystyrenes, ar-chlorostyrenes, vinyl naphthalenes, C1-C12 alkyl and cycloalkyl acrylates and lower aklyl substituted acrylates, which may be polymerized alone or in admixture with one another or with other monomers, e.g. isobutylene, butadiene, acrylontrile, N-vinyl carbazole, vinylidene chloride and divinyl benzene. Volatile organic liquids specified are butane, pentane, neopentane, hexane, cyclohexane and low-boiling petroleum ether. Example (3) describes the use of pentane to produce an expanded styrenedivinyl benzene copolymer. Specifications 775,409 and 784,028 are referred to.