Method for preparing monovinyl aromatic monomer-acrylonitrile copolymer

Claim 1

A method for the preparation of a monovinyl aromatic monomer-acrylonitrile copolymer, steps of the method comprising providing a polymerizable stream, the stream comprising from 5 to 75 parts by weight of acrylonitrile and from 95 to 25 parts by weight of a monovinyl aromatic monomer, the stream containing from about 5 × 10 -5 to 1 × 10 -2 parts by weight per part by weight of the polymerizable stream of a free radical initiating catalyst, the catalyst having a half-life of about 1 hour at a temperature in the range of 80° C to 180° C, maintaining the stream at a polymerization temperature in excess of 80° C sufficient to cause at least from 20 to 200 percent conversion of the monomer to polymer per hour wherein the copolymer contains not more than 7.5 × 10 -5 parts by weight per part of copolymer of free acrylonitrile and not more than 7 × 10 -3 parts by weight, per part of copolymer, of co-oligomers of stryene and acrylonitrile.

Claim 2

A method for the preparation of a monovinyl aromatic monomer-acrylonitrile copolymer, steps of the method comprising providing a polymerizable stream, the stream comprising from 5 to 75 parts by weight of acrylonitrile and from 95 to 25 parts by weight of a monovinyl aromatic monomer, the stream containing from about 5 × 10 -5 to 1 × 10 -2 parts by weight per part by weight of the polymerizable stream of a free radical initiating catalyst, the catalyst having a half-life of about 1 hour at a temperature in the range of 80° C to 180° C, maintaining the stream at a polymerization temperature in excess of 80° C sufficient to cause at least from 20 to 200 percent conversion of the monomer to polymer per hour wherein the copolymer contains not more than 7.5 × 10 -5 parts by weight per part of copolymer of free acrylonitrile and not more than 7 × 10 -3 parts by weight, per part of copolymer, of co-oligomers of stryene and acrylonitrile.

Claim 5

A method for the preparation of a monovinyl aromatic monomer-acrylonitrile copolymer, steps of the method comprising providing a polymerizable stream, the stream comprising from 5 to 75 parts by weight of acrylonitrile and from 95 to 25 parts by weight of a monovinyl aromatic monomer, the stream containing from about 5 × 10 -5 to 1 × 10 -2 parts by weight per part by weight of the polymerizable stream of a free radical initiating catalyst, the catalyst having a half-life of about 1 hour at a temperature in the range of 80° to 180° C, maintaining the stream at a polymerization temperature sufficient to cause at least from 20 to 200 percent conversion of the monomer to polymer per hour, the polymerization being conducted at a temperature in excess of 80° C to provide a polymer having a desirably high heat-distortion temperature and little tendency to generate acrylonitrile on heat fabrication.

Claim 6

A method for the preparation of a monovinyl aromatic monomer-acrylonitrile copolymer, steps of the method comprising providing a polymerizable stream, the stream comprising from 5 to 75 parts by weight of acrylonitrile and from 95 to 25 parts by weight of a monovinyl aromatic monomer, the stream containing from about 5 × 10 -5 to 1 × 10 -2 parts by weight per part by weight of the polymerizable stream of a free radical initiating catalyst, the catalyst having a half-life of about 1 hour at a temperature in the range of 80° to 180° C, maintaining the stream at a polymerization temperature sufficient to cause at least from 20 to 200 percent conversion of the monomer to polymer per hour, the polymerization being conducted at a temperature in excess of 80° C to provide a polymer having a desirably high heat-distortion temperature and little tendency to generate acrylonitrile on heat fabrication.