Abstract: A method for producing a vinyl polymer including a polymerization step of using a composition including a microcapsule and polymerizing a vinyl monomer by radical reaction to produce a vinyl polymer, in which the microcapsule has a core/shell structure, and the shell includes a water-soluble polymer and the core includes an organic peroxide. The water-soluble polymer is preferably at least one water-soluble polymer selected from the group consisting of polyvinyl alcohol, cellulose derivatives, gelatin, poly(meth)acrylic acid derivatives, polyvinylpyrrolidone, and polyethylene oxide.

Abstract: A method for producing a vinyl chloride type polymer is to produce the vinyl chloride type polymer by polymerizing a vinyl chloride monomer, or a mixture of a vinyl chloride monomer with a monomer copolymerizable with the vinyl chloride monomer in an aqueous medium by using a polymerization reactor. An aqueous solution of a copolymerized polyether having a weight-average molecular weight of 1,000 to 3,500 with a mole ratio of ethylene oxide to propylene oxide in the range of 10/90 to 60/40 is charged into the polymerization reactor with an amount of 0.005 to 0.050 part by weight as the copolymerized polyether relative to 100 parts by weight of the vinyl chloride monomer.

Abstract: A method for producing a vinyl chloride type polymer is to produce the vinyl chloride type polymer by polymerizing a vinyl chloride monomer, or a mixture of a vinyl chloride monomer with a monomer copolymerizable with the vinyl chloride monomer in an aqueous medium by using a polymerization reactor. An aqueous solution of a copolymerized polyether having a weight-average molecular weight of 1,000 to 3,500 with a mole ratio of ethylene oxide to propylene oxide in the range of 10/90 to 60/40 and having an alkyl group or an aryl group at both the terminals thereof is charged into the polymerization reactor with an amount of 0.005 to 0.050 parts by weight as the copolymerized polyether relative to 100 parts by weight of the vinyl chloride monomer.

Abstract: A microcapsule includes a core/shell structure, in which the shell includes a water-soluble polymer and the core includes an organic peroxide. The water-soluble polymer is preferably at least one water-soluble polymer selected from the group consisting of polyvinyl alcohol, gelatin, poly(meth)acrylic acid derivatives, polyvinyl pyrrolidone, and polyethylene oxide. The polyvinyl alcohol is preferably partially saponified polyvinyl alcohol having a degree of saponification of 80% by mole or more and 99.5% by mole or less and an average degree of polymerization of 1,500 or more and 3,500 or less.

Abstract: A microcapsule includes a core/shell structure, in which the shell includes a water-soluble polymer and the core includes an organic peroxide. The water-soluble polymer is preferably at least one water-soluble polymer selected from the group consisting of polyvinyl alcohol, gelatin, poly(meth)acrylic acid derivatives, polyvinyl pyrrolidone, and polyethylene oxide. The polyvinyl alcohol is preferably partially saponified polyvinyl alcohol having a degree of saponification of 80% by mole or more and 99.5% by mole or less and an average degree of polymerization of 1,500 or more and 3,500 or less.

Abstract: A method for producing a vinyl polymer including a polymerization step of using a composition including a microcapsule and polymerizing a vinyl monomer by radical reaction to produce a vinyl polymer, in which the microcapsule has a core/shell structure, and the shell includes a water-soluble polymer and the core includes an organic peroxide. The water-soluble polymer is preferably at least one water-soluble polymer selected from the group consisting of polyvinyl alcohol, cellulose derivatives, gelatin, poly(meth)acrylic acid derivatives, polyvinylpyrrolidone, and polyethylene oxide.

Abstract: A process for polymerizing vinyl chloride or a monomer mixture containing vinyl chloride in an aqueous medium in a polymerization vessel fitted with a reflux condenser, characterized by starting to add (A) an anti-foam agent, and (B) a partially saponified polyvinyl alcohol with an average degree of polymerization of 100 to 500 and a saponification degree of 75 to 85 mole %, to a reaction mixture during the operation of said reflux condenser, and continuing the addition of (A) and (B) until recovery of unreacted monomers from said polymerization vessel is completed, thereby preventing the polymer slurry from foaming, rising, or scattering during polymerization or recovery of unreacted monomers.

Abstract: A production process for a vinyl-based polymer is provided. The production process comprises a step for polymerizing a vinyl-based monomer by a radical reaction within an aqueous medium in a polymerization vessel, and a step for supplying a reaction inhibitor with a melting point of no more than 40° C. from a reaction inhibitor supply tank to the polymerization vessel via a reaction inhibitor supply pipe. The reaction inhibitor supply tank and the reaction inhibitor supply pipe are heated, and the reaction inhibitor is added to the polymerization vessel in a liquid state with a viscosity of no more than 200 mPa·s. The reaction inhibitor can be added to the polymerization mixture without the use of an organic solvent even at low temperatures, and problems such as the solidification of the reaction inhibitor inside the supply tank or piping, and subsequent blocking of the piping do not occur.

Abstract: A production process for a vinyl-based polymer is provided. The production process comprises a step for polymerizing a vinyl-based monomer by a radical reaction within an aqueous medium in a polymerization vessel, and a step for supplying a reaction inhibitor with a melting point of no more than 40° C. from a reaction inhibitor supply tank to the polymerization vessel via a reaction inhibitor supply pipe. The reaction inhibitor supply tank and the reaction inhibitor supply pipe are heated, and the reaction inhibitor is added to the polymerization vessel in a liquid state with a viscosity of no more than 200 mPa·s. The reaction inhibitor can be added to the polymerization mixture without the use of an organic solvent even at low temperatures, and problems such as the solidification of the reaction inhibitor inside the supply tank or piping, and subsequent blocking of the piping do not occur.

Abstract: A process for producing a vinyl chloride polymer is provided. This process includes polymerizing vinyl chloride or a monomer mixture containing vinyl chloride in an aqueous medium in a polymerization vessel fitted with a reflux condenser. This process is characterized by starting to add (A) an anti-foam agent, and (B) a partially saponified polyvinyl alcohol with an average degree of polymerization of 100 to 500 and a saponification degree of 75 to 85 mole %, to a reaction mixture during the operation of said reflux condenser, and continuing the addition of (A) and (B) until recovery of unreacted monomers from said polymerization vessel is completed. According to the process, it is possible to prevent the polymer slurry from foaming, rising, or scattering during polymerization or recovery of unreacted monomers.