Kureha Kagaku Kogyo Kabushiki Kaisha

Haruki Isaka

Haruhiko Yusa

Mitsuru Hoshino

Masanori Oota

In a process for producing a rubber-containing graft copolymer, which comprises bringing a latex of a graft copolymer comprising 60% to 90% by weight of a rubbery polymer and 40% to 10% by weight of a hard polymer, said graft copolymer latex being obtained by emulsion polymerizing a hard polymer-forming monomer in a latex of said rubbery polymer and having a minimum film-forming temperature of 75.degree. C. or less, into contact with an aqueous electrolyte solution under stirring, thereby to coagulate the latex, and recovering the precipitated graft copolymer, the improvement is disclosed such that the graft copolymer latex is subjected to slow coagulation so as to allow the graft copolymer to precipitate as substantially spherical particles, wherein the term 'slow coagulation' refers to coagulation which proceeds at a milder rate than that of coagulation in which the aqueous electrolyte solution is hydrochloric acid and the pH of the latex during coagulation is 1.8 or less.

Process for producing rubber-based graft copolymers

Modified titanium oxide is prepared by polymerizing a mixture of vinyl chloride and a carboxylic monomer such as 10-undecenoic acid in the presence of titanium oxide. The thus obtained, modified titanium oxide is mixed with a vinyl chloride resin, typically, polyvinyl chloride to give a vinyl chloride resin composition having an improved weatherability and being substantially free of serious drawbacks accompanying the addition of conventional titanium oxide such as plating out during extrusion and decrease in extrusion throughput.

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Iwaki, Japan

Haruki Isaka