Abstract: Provided is a dispersion stabilizer for suspension polymerization that contains a hydroxypropylmethylcellulose with a degree of methoxy group substitution of 27 to 30% by mass and a degree of hydroxypropoxy group substitution of 5 to 12% by mass, in which the viscosity at 20° C. of a 2% by mass aqueous solution of the hydroxypropylmethylcellulose is within a range from 5 to 1,600 mPa·s, and in 2 ml of a 0.2% by mass solution of the hydroxypropylmethylcellulose, the number of undissolved fibers with a particle size within a range from 8 to 200 ?m, as measured by a Coulter counter method, is not more than 1,000, and the number of undissolved fibers with a particle size of 50 ?m or greater measured using the same method is not more than 20. By employing a method of producing a vinyl chloride-based polymer that uses this dispersion stabilizer, a vinyl chloride-based polymer with extremely low levels of fish eyes and defects derived from foreign objects can be produced.

Abstract: Vinyl chloride or a monomer mixture containing it transported over a long distance or stored for a long period usually contains a polymerization inhibitor and Fe ions. If this kind of vinyl chloride or monomer mixture is polymerized, stirring torque during the polymerization increases, and heat removal by the cooling jacket of a polymerization vessel tends to become insufficient, making the polymer quality subject to bad influences. In the present invention, a hydroxycarboxylic acid compound is added to the polymerization mixture in an amount of 50-1000 ppm relative to the monomer or monomer mixture. As a result, an increase in stirring torque during polymerization is suppressed, and heat removal by the cooling jacket of the polymerization vessel can be performed effectively, making it possible to obtain vinyl chloride of good quality.

Abstract: Vinyl chloride or a monomer mixture containing it transported over a long distance or stored for a long period usually contains a polymerization inhibitor and Fe ions. If this kind of vinyl chloride or monomer mixture is polymerized, stirring torque during the polymerization increases, and heat removal by the cooling jacket of a polymerization vessel tends to become insufficient, making the polymer quality subject to bad influences. In the present invention, a hydroxycarboxylic acid compound is added to the polymerization mixture in an amount of 50-1000 ppm relative to the monomer or monomer mixture. As a result, an increase in stirring torque during polymerization is suppressed, and heat removal by the cooling jacket of the polymerization vessel can be performed effectively, making it possible to obtain vinyl chloride of good quality.

Abstract: A resist composition comprising an alkali-soluble resin, typically a partially t-butoxycarbonylated polyhydroxystyrene, a p-butoxystyrene/t-butylacrylate copolymer or p-butoxystyrene/maleic anhydride copolymer as a dissolution inhibitor, and a iodonium or sulfonium salt as a photoacid generator is effective for forming a resist film which can be precisely and finely patterned using high energy radiation such as a KrF excimer laser.

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 polymer scale preventive process for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising (A) a water-soluble basic polysaccharide and (B) a phenothiazine. The process is used for forming a coating on the inner wall, etc. of a polymerization vessel, and highly safe for operators. Deposition of polymer scale can be effectively prevented, and polymeric product with high whiteness or a low initial coloration is obtained.

Abstract: A process to inhibit scale adhesion to the interior of a polymerization vessel using a two part coating composition. The coating is a hydroxyanthraquinone compound used in conjunction with a water soluble salt of chitosan, applied as a solution and dried on the vessel interior. Advantages of the coating are its effective scale prevention, unaltered color of the polymer product and low toxicity.

Abstract: A process and coated vessel for use in the prevention of scale adhesion during the polymerization of a monomer having an ethylenic double bond, the two part coating comprising an N-substituted leucophenothiazine dye having the general formula (I): wherein Z is a carbonyl group or a sulfonyl group, R.sup.1, R.sup.2 and R.sup.3 are a hydrogen atom, alkyl group, an amino group, etc., used in conjunction with a vinyl pyrrolidone polymer. The two part coating is used on the inner wall, etc. of a polymerization vessel. Deposition of polymer scale can be effectively prevented, and polymeric product with high whiteness is obtained.

Abstract: A polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising (A) a N-substituted leucophenothiazine having the general formula (I): ##STR1## wherein Z is a carbonyl group or a sulfonyl group, R.sup.1, R.sup.2 and R.sup.3 are a hydrogen atom, alkyl group, an amino group, etc., and (B) a water-soluble basic polysaccharide. The agent is used for forming a coating on the inner wall, etc. of a polymerization vessel. Deposition of polymer scale can be effectively prevented, and polymeric product with high whiteness is obtained.

Abstract: A process for suspension polymerizing vinyl chloride or a monomeric mixture containing the same in an aqueous medium comprising the step of adding a partially saponified polyvinyl alcohol having an average polymerization degree of 600 to 800 and a saponification degree of 65 to 75 mol % to a polymerization system, wherein the partially saponified polyvinyl alcohol is added before start of polymerization, and also after-added continuously or intermittently over the period from the start of polymerization to the time when a polymerization conversion of 10 to 30% is reached. By the suspension polymerization process, it is possible to obtain a vinyl chloride-based polymer having high bulk specific gravity, high gelation rate and a certain level of thermal stability and showing an effectively reduced number of fish eyes when formed into shaped products.

Abstract: A polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising (A) a nitrogen-containing organic compound having at least five continuous conjugated .pi. bonds, (B) an anionic organic compound having at least one group selected from the group consisting of the sulfonic acid group and the carboxyl group and having at least five continuous conjugated .pi. bonds, and (C) a water-soluble basic polysaccharide. The agent is used for forming a coating on the inner wall, etc. of a polymerization vessel. Deposition of polymer scale can be effectively prevented not only in the liquid phase area but also in the vicinity of the interface between the gas and liquid phases. Products formed from polymer obtained have very few fish eyes.

Abstract: A polymer scale preventive agent for use in polymerization of a monomer having an ethylenic double bond, comprising (A) a nitrogen-containing organic compound having at least five continuous conjugated .pi. bonds, (B) an anionic organic compound having at least one group selected from the group consisting of the sulfonic acid group and the carboxylic group and having at least five continuous conjugated .pi. bonds, and (C) a vinylpyrrolidone-based polymer. The agent is used for forming a coating on the inner wall, etc. of a polymerization vessel. Deposition of polymer scale can be effectively prevented not only in the liquid phase area but also in the vicinity of the interface between the gas and liquid phases. Products formed from polymer obtained have very few fish eyes.

Abstract: An apparatus for continuous polymerization of vinyl chloride or a vinyl chloride-based monomeric mixture, comprising a pre-mixer 1 for preparing an aqueous suspension of the vinyl chloride or vinyl chloride-based monomeric mixture, and a polymer slurry tank 5 connected to the pre-mixer 1 through a polymerization passage comprising a piping 3, wherein a pump comprising a conical hub and an impeller mounted thereon comprised of a single spiral blade is used for drawing out the aqueous suspension from the pre-mixer into the polymerization passage and for discharging a polymer slurry formed in the passage into the slurry tank, and the polymerization passage has a length sufficient for permitting the vinyl chloride or vinyl chloride-based monomeric mixture contained in the aqueous suspension flowing through the passage to be polymerized to a predetermined extent while passing through the passage.

Abstract: A polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising a pyrogallol-acetone resin. The agent is used for forming a coating on the inner wall, etc. of a polymerization vessel. Deposition of polymer scale can be effectively prevented, and polymeric product with high whiteness is obtained.

Abstract: A polymer scale preventive agent for use in polymerization of a monomer having an ethylenic double bond, comprising at least one compound selected from the group consisting of agars and agaroses. A process of producing a polymer by polymerizing the monomer in a polymerization vessel having on its inner wall surfaces a coating comprising the scale preventive agent. Polymer scale deposition inside the polymerization can be effectively prevented, and polymers with high whiteness can be prepared. Moreover, the scale preventive agent no poisonousness and is highly safe.

Abstract: A method for recovering unreacted monomers during preparation of a vinylic polymer comprises the steps of polymerizing a vinyl monomer in an aqueous medium in a polymerizer and then recovering unreacted monomers from the polymerization system, wherein a gas evacuation rate per unit charge weight of the monomer is controlled to the range of from 60 to 300 Nm.sup.3 /hr per ton of the monomer from the initiation of the monomer recovery till the pressure in the polymerizer reaches 2.5 kg/cm.sup.2 G and a superficial gas linear velocity is reduced to a level of not more than 0.008 m/sec when the pressure in the polymerizer reaches 2.5 kg/cm.sup.2 G. The method makes it possible to recover unreacted monomers quickly without causing carrying over of polymer particles formed and is effective to maintain high quality of vinylic polymers produced.

Abstract: A polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising (A) a water-soluble basic polysaccharide and (B) an organic acid compound. The agent is used for forming a coating on the inner wall, etc. of a polymerization vessel. Deposition of polymer scale can be effectively prevented, and polymeric product with high whiteness is obtained.