Process for producing ASA plastics

Patent metadata

Field	Value
Publication number	US-11059965-B2
Application number	US-201716334936-A
Country	US
Kind code	B2
Filing date	Sep 25, 2017
Priority date	Sep 27, 2016
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

The invention relates to a process for producing thermoplastic molding materials based on acrylonitrile-styrene-acrylate copolymers (ASA) having improved surface properties, in particular an improved stability of surface quality during storage in a hot and humid environment and a reduced content of residual monomers. The invention further relates to the use of a fluidized bed dryer and/or a flow dryer in the production of thermoplastic ASA molding materials for improving surface quality and the use of a fluidized bed dryer and/or a flow dryer in the production of thermoplastic ASA molding materials for reducing the content of residual monomers. The invention further provides ASA molding materials producible by means of the process according to the invention and also moldings.

First claim

What is claimed is:

1. A process for the production of a thermoplastic molding composition comprising:
A: from 5 to 90% by weight of at least one thermoplastic copolymer A, produced from:
A1: from 50 to 95% by weight, based on the copolymer A, of a monomer A1 selected from styrene, α-methylstyrene, and mixtures of styrene with at least one other monomer selected from α-methylstyrene, p-methylstyrene, and C 1 -C 8 -alkyl (meth)acrylate; and
A2: from 5 to 50% by weight, based on the copolymer A, of a monomer A2 selected from acrylonitrile and mixtures of acrylonitrile with at least one other monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, anhydrides of unsaturated carboxylic acids, and imides of unsaturated carboxylic acids,

B: from 5 to 70% by weight of at least one graft copolymer B comprising:
B1: from 50 to 90% by weight, based on the graft copolymer B, of at least one graft base B1 which is obtained via emulsion polymerization of:
B11: from 70 to 99.9% by weight, based on the graft base B1, of at least one C 1 -C 8 -alkyl (meth)acrylate, as monomer B11;
B12: from 0.1 to 10% by weight, based on the graft base B1, of at least one polyfunctional crosslinking monomer B12; and
B13: from 0 to 29.5% by weight, based on the graft base B1, of at least one other monomer B13 selected from styrene, α-methylstyrene, C 1 -C 4 -alkylstyrene, acrylonitrile, methacrylonitrile, isoprene, butadiene, chloroprene, methyl methacrylate, alkylene glycol di(meth)acrylate, and vinyl methyl ether,
where the entirety of B11+B12+B13 provides precisely 100% by weight; and

B2: from 10 to 50% by weight, based on the graft copolymer B, of at least one graft shell B2 which is obtained via emulsion polymerization, in the presence of the at least one graft base B1, of:
B21: from 50 to 100% by weight, based on the graft shell B2, of a monomer B21, selected from styrene, α-methylstyrene, and mixtures of styrene with at least one other monomer selected from α-methylstyrene, p-methylstyrene, and C 1 -C 4 -alkyl (meth)acrylate; and
B22: from 0 to 50% by weight, based on the graft shell B2, of a monomer B22 selected from acrylonitrile and mixtures of acrylonitrile with at least one other monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, anhydrides of unsaturated carboxylic acids, and imides of unsaturated carboxylic acids,

where the entirety of graft base B1 and graft shell B2 provides precisely 100% by weight; and

C: from 0 to 90% by weight of at least one other polymeric component C; and
K: from 0 to 40% by weight of at least one other component K selected from additives and auxiliaries;

comprising the steps of:
a) precipitation of the at least one graft copolymer B after the emulsion polymerization procedure via addition of a precipitation solution comprising at least one salt;
b) mechanical dewatering of the precipitated graft copolymer B, where a graft copolymer B with water content smaller than or equal to 50% by weight is obtained;
c) drying of the dewatered graft copolymer B with the use of a drying gas, where the graft copolymer B is moved within the drying gas and the temperature of the drying gas is in the range from 50 to 160° C.; and
d) mixing of the thermoplastic copolymer A with the dried graft copolymer B and optionally the other polymeric component(s) C and optionally the other component(s) K,
wherein the dried graft copolymer B obtained in step c) has a water content in the range from 0.05 to 0.6% by weight and a total content of residual monomers lower than 200 ppm, based on the dried graft copolymer B,
wherein the drying of the graft copolymer in step c) is continued for a further 5 to 30 min starting at the juncture at which a water content of 2% by weight is achieved.

2. The process of claim 1 , wherein the drying of the dewatered graft copolymer B in step c) uses a fluidized-bed dryer and/or a pneumatic dryer.

3. The process of claim 1 , wherein the median particle diameter d 50 of the graft copolymer B is in the range from 50 to 1000 nm.

4. The process of claim 1 , wherein the graft copolymer B comprises:
from 10 to 50% by weight, based on the graft copolymer B, of at least one graft shell B2 which is obtained via emulsion polymerization of:
B21: from 50 to 95% by weight, based on the graft shell B2, of the monomer B21; and
B22: from 5 to 50% by weight, based on the graft shell B2, of the monomer B22,
where the entirety of B21 and B22 provides precisely 100% by weight.

5. The process of claim 1 , wherein the at least one graft copolymer B comprises:
B1: from 55 to 65% by weight, based on the graft copolymer B, of the at least one graft base B1; and
B2: from 35 to 45% by weight, based on the graft copolymer B, of at least one graft shell B2 which is obtained via emulsion polymerization, in the presence of the at least one graft base B1, of:
B21: from 65 to 80% by weight, based on the graft shell B2, of a monomer B21 selected from styrene and α-methylstyrene; and
B22: from 20 to 35% by weight, based on the graft shell B2, of a monomer B22 selected from acrylonitrile and mixtures of acrylonitrile with methacrylonitrile,

where the entirety of graft base B1 and graft shell B2 provides precisely 100% by weight.

6. The process of claim 1 , wherein the at least one graft copolymer B comprises:
B1: from 50 to 70% by weight, based on the graft copolymer B, of the at least one graft base B1;
B2′: from 10 to 30% by weight, based on the graft copolymer B, of at least one graft shell B2′ which is obtained via emulsion polymerization, in the presence of the at least one graft base B1, of:
B21′: 100% by weight, based on the graft shell B2′, of a monomer B21′ selected from styrene, α-methylstyrene, and mixtures of styrene with at least one other monomer selected from α-methylstyrene, p-methylstyrene, and C 1 -C 4 -alkyl (meth)acrylate; and

B2″: from 20 to 40% by weight, based on the graft copolymer B, of at least one graft shell B2″ which is obtained via emulsion polymerization, in the presence of the graft base B1 grafted with B2′, of:
B21″: from 50 to 95% by weight, based on the graft shell B2″, of a monomer B21″ selected from styrene, α-methylstyrene, and mixtures of styrene with at least one other monomer selected from α-methylstyrene, p-methylstyrene, and C 1 -C 4 -alkyl (meth)acrylate; and
B22″: from 5 to 50% by weight, based on the graft shell B2″, of a monomer B22″ selected from acrylonitrile and mixtures of acrylonitrile with at least one other monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, anhydrides of unsaturated carboxylic acids, and imides of unsaturated carboxylic acids.

7. The process of claim 1 , wherein the drying in step c) is carried out a drying gas selected from air and/or nitrogen,
where the drying is carried out with use of a fluidized-bed dryer, and the temperature of the drying gas is in the range from 50 to 160° C.; or
where the drying is carried out with use of a pneumatic dryer, and the temperature of the drying gas is in the range from 100 to 160° C.

8. The process of claim 1 , wherein the drying in step c) is carried out by a drying gas selected from air and/or nitrogen,
where the drying is carried out with use of a fluidized-bed dryer, the temperature of the drying gas is in the range from 50 to 160° C., and the average residence time of the graft copolymer B in the fluidized-bed dryer is from 1 to 60 min; or
where the drying is carried out with use of a pneumatic dryer, the temperature of the drying gas is in the range from 100 to 160° C., and the average residence time of the graft copolymer B in the pneumatic dryer is from 1 to 300 seconds.

9. The process of claim 1 , wherein the drying of th

Assignees

• Ineos Styrolution Group Gmbh

Inventors

• Fischer Wolfgang
• Jansen Ulrich
• Schulz Tobias

Classifications

• C08L2207/53

  Core-shell polymer · CPC title

• C08L2205/035

  containing four or more polymers in a blend · CPC title

• C08L69/00

  Compositions of polycarbonates; Compositions of derivatives of polycarbonates · CPC title

• C08L25/12 Primary

  with unsaturated nitriles · CPC title

• C08F6/008

  Treatment of solid polymer wetted by water or organic solvents, e.g. coagulum, filter cakes · CPC title