Polymer particle composition and process for producing the same

1. A molding thermoplastic polymer particle composition comprising molding thermoplastic polymer particles comprising:

100 parts by weight of suspension polymer particles having a glass transition temperature of 60° C. or more and an average particle diameter of 50 to 500 μm produced by suspension polymerization, and

5 (inclusive) to 22 (exclusive) parts by weight of an emulsion polymer produced by emulsion polymerization,

wherein the suspension polymer particles comprise 30 to 100% by weight of (meth)acrylate and 0 to 70% by weight of a vinyl monomer copolymerizable therewith, and

wherein the suspension polymer particles are coated with the emulsion polymer, and the average particle diameter of the molding thermoplastic polymer particles is made greater by 3 to 50% than that of the suspension polymer particles before coating in their particle size distribution.

2. The molding thermoplastic polymer particle composition according to claim 1 , wherein the emulsion polymer is obtained by graft-polymerizing 10 to 50 parts by weight of a monomer mixture consisting of 10 to 100% by weight of methacrylate, 0 to 90% by weight of an aromatic vinyl monomer, 0 to 25% by weight of a vinyl cyanide monomer, and 0 to 20% by weight of a vinyl monomer copolymerizable therewith in the presence of 50 to 90 parts by weight of the solids content of a rubber latex having a glass transition temperature of 0° C. or less consisting of 50 to 100% by weight of acrylate, 0 to 40% by weight of an aromatic vinyl monomer, 0 to 5% by weight of a crosslinking monomer, and 0 to 10% by weight of a vinyl monomer copolymerizable therewith, such that the total amount of the emulsion polymer becomes 100 parts by weight.

3. The molding thermoplastic polymer particle composition according to claim 1 , wherein the emulsion polymer is obtained by graft-polymerizing 5 to 20 parts by weight of a monomer mixture consisting of 20 to 80% by weight of at least one monomer selected from acrylate and methacrylate excluding methyl methacrylate, 20 to 80% by weight of methyl methacrylate, and 0 to 20% by weight of a vinyl monomer copolymerizable therewith in the presence of 80 to 95 parts by weight of the solids content of a polymer latex consisting of 50 to 95% by weight of methyl methacrylate, 5 to 50% by weight of methacrylate having a C2 to C8 alkyl group, and 0 to 20% by weight of a vinyl monomer copolymerizable therewith, such that the total amount of the emulsion polymer becomes 100 parts by weight.

4. The molding thermoplastic polymer particle composition according to claim 1 , wherein the emulsion polymer has a 3-layer structure obtained by polymerizing 40 to 90 parts by weight of a monomer mixture consisting of 60 to 100% by weight of alkyl acrylate, 0 to 40% by weight of a vinyl monomer copolymerizable therewith and 0.1 to 5% by weight of a crosslinking monomer in the presence of 10 to 60 parts by weight of the solids content of a polymer latex prepared by polymerizing 40 to 100% by weight of methyl methacrylate, 0 to 60% by weight of a vinyl monomer copolymerizable therewith and 0.01 to 10% by weight of a crosslinking monomer, to give a 2-layer polymer latex, and then polymerizing 11 to 67 parts by weight of a monomer mixture consisting of 60 to 100% by weight of (meth)acrylate and 0 to 40% by weight of a vinyl monomer copolymerizable therewith in the presence of 100 parts by weight of the solids content of the resulting 2-layer polymer latex.

5. A process for producing the molding thermoplastic polymer particle composition according to claim 1 , which comprises the steps consisting of preparing a polymer suspension comprising suspension polymer particles having a glass transition temperature of 60° C. or more and an average particle diameter of 50 to 50 μm produced by suspension polymerization, mixing 5 (inclusive) to 22 (exclusive) parts by weight of an emulsion polymer with 100 parts by weight of the suspension polymer particles, regulating the mixture such that the solids content of the suspension mixed with the polymer is in the range of 35 to 40% by weight, adding an aqueous electrolyte solution at a temperature of not higher than the Vicat softening temperature of the emulsion polymer to the suspension mixed with the polymer, heating the suspension mixed with the polymer at a temperature of not lower than the Vicat softening temperature of the emulsion polymer, and recovering the molding thermoplastic polymer particles by solid-liquid separation.

6. The process for producing the molding thermoplastic polymer particle composition according to claim 5 , wherein the suspension polymer particles comprise 30 to 100% by weight of (meth)acrylate and 0 to 70% by weight of a vinyl monomer copolymerizable therewith.

7. The process for producing the molding thermoplastic polymer particle composition according to claim 6 , wherein the emulsion polymer is obtained by graft-polymerizing 10 to 50 parts by weight of a monomer mixture consisting of 10 to 100% by weight of methacrylate, 0 to 90% by weight of an aromatic vinyl monomer, 0 to 25% by weight of a vinyl cyanide monomer, and 0 to 20% by weight of a vinyl monomer copolymerizable therewith in the presence of 50 to 90 parts by weight of the solids content of a rubber latex having a glass transition temperature of 0° C. or less consisting of 50 to 100% by weight of acrylate, 0 to 40% by weight of an aromatic vinyl monomer, 0 to 5% by weight of a crosslinking monomer, and 0 to 10% by weight of a vinyl monomer copolymerizable therewith, such that the total amount of the emulsion polymer becomes 100 parts by weight.

8. The process for producing the molding thermoplastic polymer particle composition according to claim 6 , wherein the emulsion polymer is obtained by graft-polymerizing 5 to 20 parts by weight of a monomer mixture consisting of 20 to 80% by weight of at least one monomer selected from acrylate and methacrylate excluding methyl methacrylate, 20 to 80% by weight of methyl methacrylate, and 0 to 20% by weight of a vinyl monomer copolymerizable therewith in the presence of 80 to 95 parts by weight of the solids content of a polymer latex consisting of 50 to 95% by weight of methyl methacrylate, 5 to 50% by weight of methacrylate having a C2 to C8 alkyl group, and 0 to 20% by weight of a vinyl monomer copolymerizable therewith, such that the total amount of the emulsion polymer becomes 100 parts by weight.

9. The process for producing the molding thermoplastic polymer particle composition according to claim 6 , wherein the emulsion polymer has a 3-layer structure obtained by polymerizing 40 to 90 parts by weight of a monomer mixture consisting of 60 to 100% by weight of alkyl acrylate, 0 to 40% by weight of a vinyl monomer copolymerizable therewith and 0.1 to 5% by weight of a crosslinking monomer in the presence of 10 to 60 parts by weight of the solids content of a polymer latex prepared by polymerizing 40 to 100% by weight of methyl methacrylate, 0 to 60% by weight of a vinyl monomer copolymerizable therewith and 0.01 to 10% by weight of a crosslinking monomer, to give a 2-layer polymer latex, and then polymerizing 11 to 67 parts by weight of a monomer mixture consisting of 60 to 100% by weight of (meth)acrylate and 0 to 40% by weight of a vinyl monomer copolymerizable therewith in the presence of 100 parts by weight of the solids content of the resulting 2-layer polymer latex.

10. The process for producing the molding thermoplastic polymer particle composition according to claim 6 , wherein the aqueous electrolyte solution is an aqueous solution of an inorganic salt.

11. The process for producing the molding thermoplastic polymer particle composition according to claim 5 , wherein the emulsion polymer is obtained by graft-polymerizing 10 to 50 parts by weight of a monomer mixture consisting of 10 to 100% by weight of methacrylate, 0 to 90% by weight of an aromatic vinyl monomer, 0 to 25% by weight of a vinyl cyanide monomer, and 0 to 20% by weight of a vinyl monomer copolymerizable therewith in the presence of 50 to 90 parts by weight of the solids content of a rubber latex having a glass transition temperature of 0° C. or less consisting of 50 to 100% by weight of acrylate, 0 to 40% by weight of an aromatic vinyl monomer, 0 to 5% by weight of a crosslinking monomer, and 0 to 10% by weight of a vinyl monomer copolymerizable therewith, such that the total amount of the emulsion polymer becomes 100 parts by weight.

12. The process for producing the molding thermoplastic polymer particle composition according to claim 11 , wherein the aqueous electrolyte solution is an aqueous solution of an inorganic salt.

13. The process for producing the molding thermoplastic polymer particle composition according to claim 5 , wherein the emulsion polymer is obtained by graft-polymerizing 5 to 20 parts by weight of a monomer mixture consisting of 20 to 80% by weight of at least one monomer selected from acrylate and methacrylate excluding methyl methacrylate, 20 to 80% by weight of methyl methacrylate, and 0 to 20% by weight of a vinyl monomer copolymerizable therewith in the presence of 80 to 95 parts by weight of the solids content of a polymer latex consisting of 50 to 95% by weight of methyl methacrylate, 5 to 50% by weight of methacrylate having a C2 to C8 alkyl group, and 0 to 20% by weight of a vinyl monomer copolymerizable therewith, such that the total amount of the emulsion polymer becomes 100 parts by weight.

14. The process for producing the molding thermoplastic polymer particle composition according to claim 13 , wherein the aqueous electrolyte solution is an aqueous solution of an inorganic salt.

15. The process for producing the molding thermoplastic polymer particle composition according to claim 5 , wherein the emulsion polymer has a 3-layer structure obtained by polymerizing 40 to 90 parts by weight of a monomer mixture consisting of 60 to 100% by weight of alkyl acrylate, 0 to 40% by weight of a vinyl monomer copolymerizable therewith and 0.1 to 5% by weight of a crosslinking monomer in the presence of 10 to 60 parts by weight of the solids content of a polymer latex prepared by polymerizing 40 to 100% by weight of methyl methacrylate, 0 to 60% by weight of a vinyl monomer copolymerizable therewith and 0.01 to 10% by weight of a crosslinking monomer, to give a 2-layer polymer latex, and then polymerizing 11 to 67 parts by weight of a monomer mixture consisting of 60 to 100% by weight of (meth)acrylate and 0 to 40% by weight of a vinyl monomer copolymerizable therewith in the presence of 100 parts by weight of the solids content of the resulting 2-layer polymer latex.

16. The process for producing the molding thermoplastic polymer particle composition according to claim 5 , wherein the aqueous electrolyte solution is an aqueous solution of an inorganic salt.