Modified polyvinyl alcohol and process for producing the same

Patent metadata

Field	Value
Publication number	US-10005867-B2
Application number	US-81679105-A
Country	US
Kind code	B2
Filing date	Aug 29, 2005
Priority date	Mar 8, 2005
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

The present invention provides modified PVA having unsaturated double bonds derived from a specific monomer in the main chain of the molecule. A modified polyvinyl alcohol containing bond units of the formula (1) having double bonds in its molecular main chain:

wherein each of X1 and X2 is a C 1-12 lower alkyl group, a hydrogen atom or a metal atom, g is an integer of from 0 to 3, h is an integer of from 0 to 12, Y1 is a hydrogen atom or —COOM, and M is a hydrogen atom, an alkyl group or a metal atom.

First claim

The invention claimed is:

1. A modified polyvinyl alcohol containing bond units of formula (1) in its molecular main chain:

wherein each of X1 and X2 is a methyl group, g is an integer of from 0 to 3, h is 0, Y1 is a hydrogen atom; and
0 to 20 mol % of copolymerizable monomers
obtained by copolymerizing at least one monomer having an ethylenically unsaturated double bond of formula (3) and a monomer having a vinyl ester unit by solution polymerization in methanol and saponifying an obtained copolymer

wherein each of X3 and X4 is a methyl group i is 0, Y2 is a hydrogen atom
wherein said monomer having an ethylenically unsaturated double bond and said monomer having a vinyl ester unit are continuously added to a polymerizer and
wherein said modified polyvinyl alcohol has a saponification degree of from 30 to 99.9 mol % and does not contain units from polymerization of any of itaconic acid, maleic acid and maleic anhydride.

2. The modified polyvinyl alcohol according to claim 1 , which shows an absorbance of at least 0.05 at 270 nm in the ultraviolet absorption spectrum of its 0.2 mass % aqueous solution, methanol solution or water/methanol mixed solution.

3. The modified polyvinyl alcohol according to claim 1 , which shows a peak top at 265 to 275 nm in the ultraviolet absorption spectrum attributable to a structure of formula (2):

4. The modified polyvinyl alcohol according to claim 1 , wherein the content of unmodified polyvinyl alcohol residues is at most 25 mass %.

5. A process for producing the modified polyvinyl alcohol as defined in claim 1 , which comprises copolymerizing at least one monomer of formula (3), a monomer having a vinyl ester unit; and 0 to 20 mol % of copolymerizable monomers, and then saponifying the obtained copolymer:

wherein each of X3 and X4 is a methyl group i is 0, Y2 is a hydrogen atom.

6. The process for producing the modified polyvinyl alcohol according to claim 5 , which comprises copolymerizing, in addition to said at least one monomer of formula (3) and said monomer having a vinyl ester unit, other monomers copolymerizable with these monomers, and then saponifying the obtained copolymer.

7. The modified polyvinyl alcohol according to claim 1 , wherein a content of monomer having an ethylenically unsaturated double bond in the modified polyvinyl alcohol is from 0.1 to 50 mol %.

8. The modified polyvinyl alcohol according to claim 1 , wherein a content of monomer having an ethylenically unsaturated double bond in the modified-polyvinyl alcohol is from 0.1 to 10 mol %.

9. The modified polyvinyl alcohol according to claim 1 , having a number average molecular weight of from 1,900 to 66,500.

10. The modified polyvinyl alcohol according to claim 1 , having a number average molecular weight of from 3,800 to 28,500.

11. The modified polyvinyl alcohol according to claim 1 , wherein a 0.2 mass % aqueous, methanol or aqueous methanol solution of said modified polyvinyl alcohol has an absorbance at 270 nm of at least 0.05.

12. The modified polyvinyl alcohol according to claim 1 , wherein a 0.2 mass % aqueous, methanol or aqueous methanol solution of said modified polyvinyl alcohol has an absorbance at 270 nm of at least 0.10.

13. The modified polyvinyl alcohol according to claim 1 , obtained by copolymerizing at least one monomer having an ethylenically unsaturated double bond of formulae (3) and a monomer having a vinyl ester unit.

14. The modified polyvinyl alcohol according to claim 13 , wherein the at least one monomer having an ethylenically unsaturated double bond of formulae (3) is dimethyl maleate.

Assignees

• Watanabe Satoshi
• Otake Hirohisa
• Denki Kagaku Kogyo Kk

Inventors

• Watanabe Satoshi
• Otake Hirohisa

Classifications

• C08F222/10

  Esters · CPC title

• C08F222/06 Primary

  Maleic anhydride · CPC title

• C08F8/44

  Preparation of metal salts or ammonium salts · CPC title

• C08F216/06 Primary

  Polyvinyl alcohol {; Vinyl alcohol} · CPC title

• C08F222/14

  Esters having no free carboxylic acid groups {, e.g. dialkyl maleates or fumarates} · CPC title