(Meth)acrylic polymer particle, process for production of the particle, plastisol, and article

1. A method for producing a (meth)acrylic polymer particle for a plastisol wherein a surface layer is produced by polymerizing a monomer mixture (Y), comprising:

polymerizing a monomer (X) having a (meth)acryloyl group to produce a polymer particle, and

polymerizing a monomer mixture (Y) in the presence of the polymer particle,

wherein the monomer (X) is 90 to 99.9% by mass and the monomer mixture (Y) is 0.1 to 10% by mass in terms of the ratio among monomer raw materials to be supplied for polymerization; and the monomer mixture (Y) comprises 1 to 80% by mol of a monomer (a) having a blocked isocyanate as a functional group which is capable of deblocking at 50 to 120° C., 5 to 80% by mol of a (meth)acrylate monomer (b) of at least one alcohol selected from the group consisting of an aliphatic alcohol having 2 or more carbon atoms, an aromatic alcohol, and a cyclic alkyl alcohol, and 0 to 94% by mol of a monomer (c) other than the monomer (a) and the monomer (b), and

wherein 0.01 to 1% by mol of a chain transfer agent to the total amount of the monomer mixture (Y) is added when the monomer mixture (Y) is polymerized.

2. The method for producing a (meth)acrylic polymer particle for a plastisol according to claim 1 , wherein the content of the monomer (a) having a blocked isocyanate as a functional group which is capable of deblocking at 50 to 120° C. is 7 to 80% by mol in the monomer mixture (Y).

3. A (meth)acrylic polymer particle for a plastisol produced by the method of claim 1 .

4. A plastisol composition comprising the (meth)acrylic polymer particle for a plastisol of claim 3 .

5. An article comprising the plastisol composition of claim 4 .

6. The plastisol composition according to claim 4 having an adhesive strength of 1.0 MPa or more when measured at 25° C. with a rate of pulling of 50 mm/min, wherein the adhesive strength is measured using a system as follows:

two cation electrodeposition plates, each having a width of 25 mm, length of 140 mm, and thickness of 0.8 mm, overlap each other at a length of 25 mm, the plastisol composition is filled in the overlapped space so as to have an area of 25 mm square and a thickness of 3 mm, the resultant system is heated at 120° C. for 20 minutes or at 140° C. for 20 minutes.

7. The method according to claim 1 , wherein monomer mixture (Y) is present in amount of from 1 to 3% by mass in terms of the ratio among monomer raw materials to be supplied for polymerization.

8. The method according to claim 1 , wherein monomer (a) comprises 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate.

9. The method according to claim 1 , wherein monomer (a) comprises 2-[O-(1′-methylpropylideneamino)carboxyamino]ethyl methacrylate.

10. The method according to claim 1 , wherein monomer (a) is present in an amount of 10 to 30% by mol.

11. The method according to claim 1 , wherein monomer (b) is present in an amount of 10 to 30% by mol.

12. The method according to claim 1 , wherein monomer (a) is present in an amount of 10 to 30% by mol, monomer (b) is present in an amount of 10 to 30% by mol, and monomer (c) is present in an amount of 40 to 80% by mol.

13. The method according to claim 1 , wherein blocked isocyanate groups are unevenly distributed at a surface layer of the polymer particle.