Abstract: Provided is a dispersion assistant useful for suspension polymerization of vinyl-based compounds. The dispersion assistant comprises a polyvinyl alcohol-based polymer (A) comprising a constituent unit represented by the general formula (1) shown below at 0.1 to 10 mol % per polyvinyl alcohol monomer unit and having a saponification degree of 15 to 70 mol %. (In the formula, R denotes an alkyl group.

Abstract: An object of the present invention is to provide a dispersion assistant that, when used for suspension polymerization of a vinyl-based compound, achieves stable production of a good polymer (vinyl-based resin) without much scale adhesion on the polymerization tank even in the cases where used in a large amount. Provided is a dispersion assistant for suspension polymerization, which comprises a polyvinyl alcohol-based polymer (A) having an acetal group (a) having an olefinic unsaturated double bond, the polymer having a saponification degree of 60 mol% or less.

Abstract: Provided is a dispersion assistant useful for suspension polymerization of vinyl-based compounds. The dispersion assistant comprises a polyvinyl alcohol-based polymer (A) comprising a constituent unit represented by the general formula (1) shown below at 0.1 to 10 mol % per polyvinyl alcohol monomer unit and having a saponification degree of 15 to 70 mol %. (In the formula, R denotes an alkyl group.

Abstract: Provided is a dispersion stabilizer which exhibits an excellent polymerization stability when used in suspension polymerization for a vinyl chloride-based resin, and gives a vinyl chloride-based resin having few coarse particles, few fish eyes after resin molding, an excellent plasticizer absorption, and an excellent hue. Also provided is a high-quality vinyl chloride-based resin produced using the dispersion stabilizer. The present invention is a dispersion stabilizer for suspension polymerization containing a polyvinyl alcohol-based polymer (B) which has a double bond in a side chain and which is obtainable by acetalization of a polyvinyl alcohol-based polymer (A) with a monoaldehyde having an olefinic unsaturated double bond.

Abstract: The purpose of the present invention is to provide a dispersion assistant with which it is possible to stably obtain an excellent polymeric substance (vinyl resin) with minimal adhering of scale to a polymerization vessel even when the dispersion assistant is used in a large amount in the suspension polymerization of a vinyl compound. The additive for suspension polymerization contains a polyvinyl alcohol polymer (A) that has a gelling degree of 60 mol % or less and has acetal groups (a) having olefinically unsaturated double bonds.

Abstract: Provided is a dispersion stabilizer which exhibits an excellent polymerization stability when used in suspension polymerization for a vinyl chloride-based resin, and gives a vinyl chloride-based resin having few coarse particles, few fish eyes after resin molding, an excellent plasticizer absorption, and an excellent hue. Also provided is a high-quality vinyl chloride-based resin produced using the dispersion stabilizer. The present invention is a dispersion stabilizer for suspension polymerization containing a polyvinyl alcohol-based polymer (B) which has a double bond in a side chain and which is obtainable by acetalization of a polyvinyl alcohol-based polymer (A) with a monoaldehyde having an olefinic unsaturated double bond.

Abstract: A surface-roughened film and methods for fabricating same. The film has good transparency/exceptional clarity and high lubricity so that it is useful for a photoengraving material, label, packaging film, magnetic recording film, or clear film. The film has a composition including thermoplastic polyester resin (a) and a thermoplastic resin (b), such as an amorphous nylon, having glass transition temperature preferably 10.degree. C. higher than that of the thermoplastic polyester resin (a) and a critical surface tension more than 0.1 dyne/cm different from that of the thermoplastic polyester resin (a). Resin (b) further has a melt viscosity, at a temperature of 280.degree. C. and shear rate of 10.sup.2 sec.sup.-1, in the range of 500 to 50,000 poise. One or more particulate inert inorganic compound may be added and the film may be laminated to layers of other polymers with the film of the foregoing composition on at least one surface thereof.

Abstract: A light-weight polyester film which comprises (A) from 50 to 95% by weight of a crystalline polyester resin and (B) from 5 to 50% by weight of a maleimide copolymer, said maleimide copolymer being dispersed in the film in the form of particles having diameters of from 0.1 to 20 .mu.m and fine voids being present in the film, and which has an apparent specific gravity of from 0.3 to 1.1, wherein said maleimide copolymer comprises from 30 to 50 mol % of a maleimide monomer group, from 30 to 70 mol % of an aromatic vinyl monomer group, from 0 to 40 mol % of an unsaturated dicarboxylic anhydride monomer group and from 0 to 40 mol % of other copolymerizable monomer group, and said maleimide copolymer has a glass transition temperature higher by at least 10.degree. C. than the crystalline polyester resin.