The invention relates to an organic peroxide emulsion containing at least one organic peroxide, at least one emulsifier comprising at least one nonionic surfactant including at least one fatty chain and/or a protective colloid agent, a combination of two or more antigels containing no more than 9.5 wt% of a first antifreeze relative to the total weight of the ethanol emulsion, at least a second antifreeze and water. The invention also relates to a method for preparing such an emulsion, the use of such an emulsion for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, and a halogenated vinyl polymer obtained by the use of such an emulsion.

The invention relates to an organic peroxide emulsion containing at least one organic peroxide, at least one emulsifier comprising at least one nonionic surfactant including at least one fatty chain and/or a protective colloid agent, a combination of two or more antigels containing no more than 9.5 wt% of a first antifreeze relative to the total weight of the ethanol emulsion, at least a second antifreeze and water. The invention also relates to a method for preparing such an emulsion, the use of such an emulsion for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, and a halogenated vinyl polymer obtained by the use of such an emulsion.

The invention relates to an organic peroxide emulsion containing at least one organic peroxide, at least one emulsifier comprising at least one nonionic surfactant including at least one fatty chain and/or a protective colloid agent, a combination of two or more antigels containing no more than 9.5 wt% of a first antifreeze relative to the total weight of the ethanol emulsion, at least a second antifreeze and water. The invention also relates to a method for preparing such an emulsion, the use of such an emulsion for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, and a halogenated vinyl polymer obtained by the use of such an emulsion.

A dispersion stabilizer for suspension polymerization is provided that includes a vinyl alcohol-based polymer (A), wherein a 0.1 mass % concentration aqueous solution of the polymer (A) has an absorbance (a1) of less than 0.25 at a wavelength of 280 nm, the aqueous solution has an absorbance (a2) of less than 0.030 at a wavelength of 320 nm, the polymer (A) has a degree of saponification of not less than 68 mol % and not more than 98 mol %, the polymer (A) has a viscosity-average degree of polymerization of more than 1500 and less than 4500, and the polymer (A) in powder form has a YI value of not less than 5. The dispersion stabilizer is capable of producing a vinyl-based resin that is excellent in polymerization stability, has a small particle size, and has an improved bulk density.

A dispersion stabilizer for suspension polymerization is provided that includes a vinyl alcohol-based polymer (A), wherein a 0.1 mass % concentration aqueous solution of the polymer (A) has an absorbance (a1) of less than 0.25 at a wavelength of 280 nm, the aqueous solution has an absorbance (a2) of less than 0.030 at a wavelength of 320 nm, the polymer (A) has a degree of saponification of not less than 68 mol % and not more than 98 mol %, the polymer (A) has a viscosity-average degree of polymerization of more than 1500 and less than 4500, and the polymer (A) in powder form has a YI value of not less than 5. The dispersion stabilizer is capable of producing a vinyl-based resin that is excellent in polymerization stability, has a small particle size, and has an improved bulk density.

The invention relates to an organic peroxide emulsion comprising at least one organic peroxide comprising di-sec-butyl peroxydicarbonate, at least one emulsifier, at least one antifreeze, and water; said emulsion being free of methanol and ethanol.

The invention also relates to a process for preparing such an emulsion, to the use of such an emulsion for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, and also to a halogenated vinyl polymer obtained by using such an emulsion.

The invention relates to an organic peroxide emulsion comprising at least one organic peroxide comprising di-sec-butyl peroxydicarbonate, at least one emulsifier, at least one antifreeze, and water; said emulsion being free of methanol and ethanol.

The invention also relates to a process for preparing such an emulsion, to the use of such an emulsion for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, and also to a halogenated vinyl polymer obtained by using such an emulsion.

The present disclosure provides a modified polyvinyl alcohol-based polymer, which comprises a modifying monomer unit represented by Formula ##STR00001## wherein, X is a moiety comprising an alkenyl group, and the modified polyvinyl alcohol-based polymer has a saponification degree of 67 mol % to 78 mol % and a modification rate of 0.02 mol % to 1.5 mol %. The modified polyvinyl alcohol-based polymer is suitable to be used as a dispersant for suspension polymerization, to make the obtained polyvinyl chloride-based resin have reduced particle diameter and few coarse particles.

The present disclosure provides a modified polyvinyl alcohol-based polymer, which comprises a modifying monomer unit represented by Formula ##STR00001## wherein, X is a moiety comprising an alkenyl group, and the modified polyvinyl alcohol-based polymer has a saponification degree of 67 mol % to 78 mol % and a modification rate of 0.02 mol % to 1.5 mol %. The modified polyvinyl alcohol-based polymer is suitable to be used as a dispersant for suspension polymerization, to make the obtained polyvinyl chloride-based resin have reduced particle diameter and few coarse particles.

A vinyl alcohol-based polymer according to one embodiment of the present invention has an integral value (e) of 0.8 to 20 in the case when a sum of the following integral value (a) to (e) is 100 in a .sup.1H-NMR spectrum.

(a) integral value of peak confirmed at 5.70 to 5.96 ppm
(b) integral value of peak confirmed at 5.97 to 6.63 ppm
(c) integral value of peak confirmed at 6.64 to 7.55 ppm
(d) integral value of peak confirmed at 7.56 to 7.81 ppm
(e) integral value of peak confirmed at 7.82 to 8.04 ppm