Polyvinyl acetal-based resin
View Patent ↗The present invention provides a polyvinyl acetal-based resin which has a high elastic modulus, is excellent in solubility to an alcoholic solvent, and gives a highly transparent alcohol solution. The polyvinyl acetal-based resin is obtained by acetalizing a polyvinyl alcohol-based resin (A) which has 0.1 to 1.5% by mol of a 1,2-diol structural unit represented by the following general formula (1) and a degree of saponification of 98.5% by mol or more: wherein R 1 , R 2 , and R 3 each independently represents a hydrogen atom or an organic group; X represents a single bond or a bonding chain; and R 4 , R 5 , and R 6 each independently represents a hydrogen atom or an organic group.
1. A polyvinyl acetal-based resin comprising an acetalized resin of a polyvinyl alcohol-based resin (A) comprising 0.4 to 1.2 mol % of a 1,2-diol structural unit in a side chain represented by following formula (1) and saponified to a degree of 95 mol % or higher:
wherein each of R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 independently represents a hydrogen atom or an organic group, and X represents a single bond or a bonding chain, and
the polyvinyl alcohol-based resin (A) is acetalized to a degree of 60 to 80 mol %.
2. The polyvinyl acetal-based resin according to claim 1 , wherein all of R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are a hydrogen atom, and X is a single bond in the formula (1).
3. The polyvinyl acetal-based resin according to claim 1 , wherein the polyvinyl alcohol-based resin (A) is a saponified copolymer of a vinyl ester-based monomer with a compound represented by following formula (2):
wherein each of R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 independently represents a hydrogen atom or an organic group; X represents a single bond or a bonding chain; and each of R 7 and R 8 independently represents a hydrogen atom or R 9 —CO— where R 9 is an alkyl group.
4. The polyvinyl acetal-based resin according to claim 1 , wherein the polyvinyl alcohol-based resin (A) is acetalized with butyraldehyde.
5. The polyvinyl acetal-based resin according to claim 1 ,
wherein the organic group for R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 is an alkyl group having 1 to 4 carbon atoms, wherein one or more hydrogen atoms of the alkyl group are optionally substituted with at least one group independently selected from the group consisting of a halogen group, a hydroxyl group, an ester group, a carboxylic acid group, and a sulfonic acid group.
6. The polyvinyl acetal-based resin according to claim 1 ,
wherein the polyvinyl alcohol-based resin (A) has an average polymerization degree in a range from 100 to 4,000 when measured according to JIS K6726.
7. The polyvinyl acetal-based resin according to claim 1 , wherein elastic modulus of the polyvinyl acetal-based resin is higher than elastic modulus of a polyvinyl acetal-based resin having no 1,2-diol structural unit in a side chain.
8. The polyvinyl acetal-based resin according to claim 1 ,
wherein the polyvinyl acetal-based resin is soluble in alcohol, and
the polyvinyl acetal-based resin has stable storage viscosity.