Vinyl alcohol polymer, method for producing vinyl alcohol polymer, dispersant for suspension polymerization, dispersion aid for suspension polymerization, and method for producing vinyl polymer

1 . A vinyl alcohol polymer, comprising, in the same molecule or in different molecules:

a carbonyl group, in which two atomic bonds both bond to a carbon atom;

a formyl group; and

a vinyl group of formula (5) comprising an alkenyl group at a first end of a polymer chain:

wherein, in the formula (5), n is an integer in a range of from 1 to 11,

wherein the vinyl alcohol polymer is one molecule or a mixture of multiple different vinyl alcohol polymers.

2 . The vinyl alcohol polymer of claim 1 , comprising a carbonyl structure of formula (1) comprising the carbonyl group:

wherein, in the formula (1), m is an integer in a range of from 1 to 11.

3 . A vinyl alcohol polymer, comprising, at a second end of a polymer chain, a carbonyl side group of formula (2):

wherein, in the formula (2), R 1 is an alkenyl group comprising a methylene group at an end of the carbonyl side group.

4 . The vinyl alcohol polymer of claim 1 , comprising a tertiary carbon atom.

5 . The vinyl alcohol polymer of claim 1 , comprising a structural unit derived from an unsaturated aliphatic aldehyde.

6 . The vinyl alcohol polymer of claim 5 , wherein the unsaturated aliphatic aldehyde has 3 to 14 carbon atoms.

7 . The vinyl alcohol polymer of claim 5 , wherein the unsaturated aliphatic aldehyde comprises, at an end thereof, a carbon-carbon double bond.

8 . A method for producing the vinyl alcohol polymer of claim 1 , the method comprising:

polymerizing a vinyl ester in a presence of an unsaturated aliphatic aldehyde to obtain a vinyl ester polymer; and

saponifying the vinyl ester polymer.

9 . A dispersant for suspension polymerization, the dispersant comprising:

the vinyl alcohol polymer of claim 1 .

10 . A dispersion aid for suspension polymerization, the dispersion aid comprising:

the vinyl alcohol polymer of claim 1 .

11 . A method for producing a vinyl polymer, the method comprising:

polymerizing a vinyl compound in a presence of the vinyl alcohol polymer of claim 1 .

12 . The vinyl alcohol polymer of claim 1 , wherein, in the formula (5), n is an integer in a range of from 2 to 9.

13 . The vinyl alcohol polymer of claim 1 , wherein, in the formula (5), n is an integer in a range of from 3 to 7.

14 . The vinyl alcohol polymer of claim 1 , comprising an aliphatic aldehyde-derived unit of formula (3):

wherein

R 2 to R 4 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and

q is an integer of in a range of from 1 to 11.

15 . The vinyl alcohol polymer of claim 14 , wherein, in the formula (3),

R 2 to R 4 are each a hydrogen atom, and

q is an integer in a range of from 2 to 9.

16 . The vinyl alcohol polymer of claim 14 , wherein, in the formula (3),

R 2 to R 4 are each a hydrogen atom, and

q is an integer in a range of from 3 to 7.

17 . The vinyl alcohol polymer of claim 1 , comprising an aliphatic aldehyde-derived unit of formula (4):

wherein

R 5 to R 7 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and

r is an integer of in a range of from 1 to 11.

18 . The vinyl alcohol polymer of claim 14 , wherein, in the formula (3),

R 5 to R 7 are each a hydrogen atom, and

r is an integer in a range of from 2 to 9.

19 . The vinyl alcohol polymer of claim 14 , wherein, in the formula (3),

R 5 to R 7 are each a hydrogen atom, and

r is an integer in a range of from 3 to 7.

20 . The vinyl alcohol polymer of claim 5 , wherein the unsaturated aliphatic aldehyde is 2-propenal, 3-butenal, 4-pentenal, 5-hexenal, 3-methyl-5-hexanal, 6-heptenal, 6-octenal, 7-octenal, 7-methyl-7-octenal, 3,7-dimethyl-7-octenal, 8-nonenal, 9-decenal, 10-undecenal, or 11-dodecenal.