Method for preparing monovinyl aromatic monomer-acrylonitrile copolymer
AssigneeThe Dow Chemical Company
InventorsAlan E. Platt, Robert J. Russell
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Abstract
Improved monovinyl aromatic monomer-acrylonitrile copolymers are prepared by polymerizing at temperatures above 80.degree. C in the presence of certain free radical initiators, the resultant polymers are prepared at high rates of conversion, have relatively high heat distortion temperatures, have a low oligomer content and generate relatively little additional acrylonitrile under fabrication conditions.
Claims4
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 .times. 10.sup.-5 to 1 .times. 10.sup.-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.degree. C to 180.degree. C, maintaining the stream at a polymerization temperature in excess of 80.degree. 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 .times. 10.sup.-5 parts by weight per part of copolymer of free acrylonitrile and not more than 7 .times. 10.sup.-3 parts by weight, per part of copolymer, of co-oligomers of stryene and acrylonitrile.
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 .times. 10.sup.-5 to 1 .times. 10.sup.-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.degree. to 180.degree. 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.degree. C to provide a polymer having a desirably high heat-distortion temperature and little tendency to generate acrylonitrile on heat fabrication.
Dependencies are inferred from the claim text.