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 polymer scale deposition preventive agent comprising (a) an aromatic compound having at least eight conjugated .pi. bonds and having a molecular weight of 1,000 or more, and (b) a polyalkylene oxide having a weight-average molecular weight of 2,000 or more, wherein the weight ratio of the component (a) to the component (b) is 100/500 to 100/1, can prevent surely the deposition of polymer scale even in a polymerization system containing a monomer, such as styrene, acrylic acid esters or acrylonitrile, which has a high solvency for a coating film consisting of the conventional polymer scale deposition preventive agent.

Abstract: A process to prevent scale adhesion on rector surfaces when polymerizing vinyl esters, vinyl esthers, carboxylic acids, styrene or diene monomers. Coating of internal reactor surfaces with a combination of an amino containing aromatic compound, and an alkali metal or ammonium salt of polyvinylsulfuric acid results in the scale prevention. This combination is applied to reactor surfaces via its mixture with a solvent and is subsequently dried to form the coating.

Abstract: A process to prevent scale adhesion on reactor surfaces when polymerizing vinyl monomers. Coating of internal reactor surfaces with a combination of an amino containing aromatic compound, and an alkali metal or ammonium salt of polyvinylsulfuric acid results in the scale prevention. This combination is applied to reactor surfaces via its mixture with a solvent and is subsequently dried to form the coating.

Abstract: A polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising:(A) at least one compound selected from the group consisting of diaminobenzenes and diaminonaphthalenes,(B) a hydroxynaphthoquinone, and(C) an acid. The polymerization vessel having a coating comprising the polymer scale preventive agent on its inner wall, etc. is effective in preventing deposition of polymer scale, and the polymeric product has a high whiteness and is of high quality.

Abstract: A polymer scale preventive agent for use in polymerization of vinyl chloride monomer or a monomer mixture containing vinyl chloride monomer as a major component, comprising:(A) a naphthoquinone natural dye and(B) a polyvinyl alcohol with a saponification degree of at least 50 mol %. The polymer scale preventive agent is formed as coating on the inner wall, etc. of a polymerization vessel. Deposition of polymer scale can be always effectively prevented. Polymers with a high whiteness can be produced, and products formed from the polymer have only a small number of fish eyes.

Abstract: A polymer scale preventive agent for use in polymerization of a haloethylene or a monomer mixture containing the same, comprising:(A) an aromatic compound having at least one group selected from the class consisting of primary, secondary and tertiary amino groups, quaternary ammonium groups and the azo group and/or a dye having at least one group selected from said class, and(B) an alkali metal or ammonium salt of a polyvinylsulfonic acid, and(C) a naphthoquinone natural dye; a polymerization vessel having a coating comprising said scale preventive agnet. A process of preparing a haloethylene polymer using the vessel can produce a polymer of high quality without polymer scale deposition.

Abstract: A method of preventing polymer scale deposition in a polymerization vessel in polymerization of a particular monomer having an ethylenic double bond having a high dissolving power against the conventional scale preventive coatings, wherein said polymerization is carried out in a polymerization vessel of which the inner wall has been previously coated with a first coating liquid comprising:(A) a water-soluble anionic dye, and(B) a metal salt, to form a first coating, and the first coating thus formed has been then coated with a second coating liquid comprising:(C) an alkaline earth metal compound, and at least one member selected from the group consisting of:(D) a water-soluble anionic dye and(E) an inorganic colloid,to form a second coating. Polymer scale deposition can be effectively prevented.

Abstract: Polymer scale deposition from a polymerization medium in which a monomer having an ethylenic double bond is polymerized, is prevented by conducting the polymerization in a polymerization vessel having a coating by applying a liquid comprising (A) an organic compound containing at least one member selected from the group consisting of a sulfonic acid group and a carboxylic acid group and having a molecular weight of 1000 or less and (B) a water-insoluble compound having an absorption band in the visible light range of 540 to 750 nm, the compounds (A) and (B) having been dissolved or dispersed in (C) an ester-based organic solvent, and having a pH of 3 or less; to the inner wall surfaces of said polymerization vessel. Polymer scale can be effectively prevented and polymeric products are barely colored.

Abstract: A method of preventing polymer scale deposition in a polymerization vessel in polymerization of a particular monomer having an ethylenic double bond having a high dissolving power against the conventional scale preventive coatings, wherein said polymerization is carried out in a polymerization vessel of which the inner wall has been previously coated with a first coating solution comprising:(A) a water-soluble anionic dye, and(B) at least one member selected from the group consisting of inorganic colloids and cationic dyes, to form a first coating, and the first coating thus formed has been then coated with a second coating solution comprising:(C) an alkaline earth metal compound, and at least one member selected from the group consisting of:(D) a water-soluble anionic dye and(E) an inorganic colloid, to form a second coating. The polymerization vessel having the double coating as prepared above is also disclosed. Polymer scale deposition can be effectively prevented.

Abstract: The present invention relates to a coating solution for preventing adhesion of polymer scale and a method for preventing scale adhesion during preparation of polymers which can provide polymers having high quality without coloring thereof while preventing adhesion of polymer scale to a polymerizer when a monomer having an ethylenically unsaturated double bond is polymerized. A coating solution for preventing adhesion of polymer scale which comprises anaphthoquinone natural dyestuffs, anthraquinone natural dyestuffs, tannin natural dyestuffs, xanthone natural dyestuffs, flavonoid natural dyestuffs, or/and benzoquinone natural dyestuffs and a polyvinyl alcohol having a degree of saponification of not less than 70 mole % was applied on at least a part of a polymerizer which comes in contact with a monomer having an ethylenically unsaturated double bond and was dried to give a coating film during polymerization thereof.

Abstract: A method of preventing polymer scale deposition during polymerization of a monomer having an ethylenically double bond in a polymerization vessel, comprising the step of carrying out said polymerization in a polymerization vessel of which the inner wall surface has a coating comprising a water-soluble polysaccharide; and a polymer scale preventive agent comprising polysaccharide. By use of the method or agent, deposition of polymer scale can be effectively prevented; in addition, polymers with a high whiteness can be prepared. Moreover, the scale preventive agent used has no poisonousness or the like and is highly safe.

Abstract: Scale deposits during polymerization of monomers containing ethylene-type double bonds are prevented by coating the reactor walls and parts with cationic dyes oxidized with hydrogen peroxide.