Dispersion stabilizer for suspension polymerization and method for producing vinyl resin

Patent metadata

Field	Value
Publication number	US-9834629-B1
Application number	US-201515524336-A
Country	US
Kind code	B1
Filing date	Nov 11, 2015
Priority date	Nov 12, 2014
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

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.

First claim

The invention claimed is:

1. A dispersion stabilizer, comprising a vinyl alcohol-comprising 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.

2. The dispersion stabilizer according to claim 1 , further comprising a vinyl alcohol-comprising polymer (B),
wherein
a 0.1 mass % concentration aqueous solution of the polymer (B) has an absorbance (b1) of not less than 0.25 at a wavelength of 280 nm,
the aqueous solution has an absorbance (b2) of not less than 0.030 at a wavelength of 320 nm,
the polymer (B) has a degree of saponification of not less than 65 mol % and not more than 82 mol %, and
the polymer (B) has a viscosity-average degree of polymerization of not less than 500 and not more than 1500.

3. The dispersion stabilizer according to claim 2 , wherein a mass ratio (AB) of the vinyl alcohol-comprising polymer (A) to the vinyl alcohol-comprising polymer (B) is not less than 6/94 and not more than 60/40.

4. A method of producing a vinyl-based resin, comprising suspension-polymerizing a vinyl-comprising monomer in an aqueous medium with the dispersion stabilizer according to claim 1 .

5. The method of producing a vinyl-based resin according to claim 4 , wherein a mass ratio (vinyl-comprising monomer/aqueous medium) of the vinyl-comprising monomer to the aqueous medium is not less than 0.75.

6. The method of producing a vinyl-based resin according to claim 4 , wherein the vinyl-comprising monomer is vinyl chloride.

7. A method of producing a vinyl-based resin, comprising suspension-polymerizing a vinyl-comprising monomer in an aqueous medium with the dispersion stabilizer according to claim 2 .

8. A method of producing a vinyl-based resin, comprising suspension-polymerizing a vinyl-comprising monomer in an aqueous medium with the dispersion stabilizer according to claim 3 .

9. The method of producing a vinyl-based resin according to claim 5 , wherein the vinyl-comprising monomer is vinyl chloride.

Assignees

• Kuraray Co

Inventors

• Fukuhara Tadahito

Classifications

• C08L2205/025

  containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure · CPC title

• C08F18/08

  Vinyl acetate · CPC title

• C08L29/04

  Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids · CPC title

• C08F8/00

  Chemical modification by after-treatment (graft polymers, block polymers, crosslinking with unsaturated monomers or with polymers C08F251/00 - C08F299/00; of conjugated diene rubbers C08C) · CPC title

• C08F116/06 Primary

  Polyvinyl alcohol {; Vinyl alcohol} · CPC title