Abstract: In preparing a matte vinyl chloride polymer by suspension polymerizing a monomeric charge comprising monomeric vinyl chloride in an aqueous medium, polymerization is started in the presence of 0.05-0.25 part by weight of diallyl phthalate per 100 parts by weight of the monomeric charge, and polymerization is continued while adding 0.01-0.15 part by weight of 1,6-hexanediol di(meth)acrylate per 100 parts by weight of the monomeric charge when the rate of polymerization is in the range of 20-60%. There is produced a matte vinyl chloride-diallyl phthalate copolymer having a tetrahydrofuran-insoluble gel content of 0.5-2.5% by weight in a reproducible manner. A composition prepared by blending the copolymer with a plasticizer has minimized fish-eyes and improved matting effect.

Abstract: A method for preparing powder of a vinyl chloride polymer comprises the steps of polymerizing vinyl chloride monomer or a vinyl monomer mixture mainly comprising vinyl chloride monomer in an aqueous medium and adding, to the polymerization system, a fluorine atom-containing nonionic surfactant in an amount ranging from 0.0001 to 0.5 part by weight per 100 parts by weight of the vinyl chloride monomer or the vinyl monomer mixture mainly comprising vinyl chloride monomer after the rate of polymerization reaches at least 70% or fine powder of at least one inorganic substance having a particle size ranging from 0.001 to 50 .mu.m in an amount ranging from 0.001 to 1.0 part by weight per 100 parts by weight of the vinyl chloride monomer or the vinyl monomer mixture mainly comprising vinyl chloride monomer after the rate of polymerization reaches at least 70%.

Abstract: An improved method is proposed for the suspension polymerization of vinyl chloride monomer in an aqueous medium, by which the polyvinyl chloride resin obtained may have an increased bulk density without causing any disadvantages. The improvement can be obtained by controlling the power on the stirrer for the agitation of the polymerization mixture in such a manner that the power at the moment of the start of the polymerization reaction is 100 to 200 kgf.m/s per 1000 kg of the polymerization mixture and the power is subsequently decreased either continuously or step-wise according to a specified schedule down to 60 to 90% of the value at the start of the polymerization reaction at the moment when conversion of the monomer to polymer is 30% along with starting of the operation of the reflux condenser at a specified moment in relation to the stirrer power and the monomer conversion.

Abstract: An improved method for the suspension polymerization is proposed which gives a PVC resin product having an increased plasticizer absorptivity and greatly decreased content of fish eyes. The invention can be achieved by additionally adding a limited volume of water into the polymerization mixture under proceeding of the polymerization reaction within a specified period of 30 to 70% monomer conversion and at such a controlled rate as not to unduly decrease the pressure inside of the reactor.

Abstract: A process of preparing a lower vinyl chloride polymer which comprises suspension polymerization of a vinyl chloride monomer of a mixture of unsaturated monomers consisting essentially of vinyl chloride, in an aqueous solvent, in the presence of a straight chain alkyl vinyl compound having an epoxy end terminal group represented by the formula I: ##STR1## wherein n is an integer of 2-20.

Abstract: An improvement is proposed for decreasing triboelectric static charging of a polyvinyl chloride resin powder so as to improve the flowability of the powder and prevent a decrease in the bulk density of the powder due to static electricity. The improvement comprises, in the polymerization process of vinyl chloride monomer in an aqueous medium, adding, to the aqueous polymerization mixture, a specified amount of an aqueous dispersion containing a salt of a long-chain carboxylic acid with a divalent metal and an ester of sorbitan with a long-chain carboxylic acid in a specified weight proportion and in a specified total concentration at a moment when conversion of the monomer to polymer is at least 70%.