GB1485424A - Process for preparing impact resistant vinyl halide polymers - Google Patents

Abstract

1485424 Impact resistant vinyl halide polymers STAUFFER CHEMICAL CO 27 Nov 1974 51350/74 Heading C3P A process for the preparation of an impact resistant vinyl halide copolymer comprises: (1) in an aqueous medium, suspension polymerizing an ethylenically unsaturated monomer component consisting of 50-100%, by weight, based on the total weight of said monomer component of at least one vinyl halide monomer of formula CH=C(Halogen)Z where Z is hydrogen or halogen; and from 0-50%, by weight, of another ethylenically unsaturated comonomer copolymerizable therewith in the presence of 0À01-5% by weight, based on the total weight of monomer, of a suspending agent and a catalyst system of 0À003-0À6% by weight, based on the total weight of monomer, of a water-soluble free radical polymerization catalyst and 0À005- 1À0% by weight, based on the total weight of monomer, of a monomer-soluble free radical polymerization catalyst; (2) removing unreacted monomer after polymerization is at least 60% complete; (3) adding to an aqueous slurry of polymer particles resulting from step (2), which may have been at least partially dried and reslurried, a sufficient amount of a monomer component which forms a rubber-containing interpolymer having a Tg of less than 25‹ C. to provide at least 2%, by weight, based on the final product, of a rubber-containing interpolymer; and (4) polymerizing the said monomer component of step (3) in the presence of the product of step (2) to thereby form a vinyl halide polymer of improved impact resistance. The interpolymer may be prepared in the same aqueous system used to prepare the suspension particles or if wet cake or dried suspension particles are isolated these are reslurried in water. Numerous examples of the vinyl halide monomer, the other ethylenically unsaturated monomer, and the monomer component for forming the rubbercontaining interpolymer are specified. The suspending agent may be gelatine, hydroxy methyl cellulose, hydroxy ethyl cellulose, hydroxy propyl cellulose, carboxy methyl cellulose, talc, clay or polyvinyl alcohol. The monomer soluble catalyst may be an organic peroxy or azo compound, e.g. azobisisobutyronitrile. The water soluble catalyst may be inorganic peroxy compound, e.g. potassium persulphate, bisulphites, thiosulphates, hydrosulphites or sodium formaldehyde sulphoxylate. In the specific example vinyl chloride is suspension polymerized and the monomer charge for producing the rubber-containing interpolymer comprises butadiene, butyl acrylate, methyl methacrylate and acrylonitrile. The product is then blended with polyvinyl chloride.