Bulk copolymerization of vinyl ester

Claim 1

In the process for copolymerizing vinyl esters and α-alkenyl aromatic hydrocarbons where optionally the following monomers are also present; A. an ester, amide, and/or nitrile of an ethylenically unsaturated monocarboxylic acid having 3 to 4 carbon atoms per molecule, B. an ester of an ethylenically unsaturated dicarboxylic acid having 4-5 carbon atoms per molecule, C. an ethylenically unsaturated mono- or dicarboxylic acid, or anhydride thereof, having 3-5 carbon atoms per molecule, and D. a mono-ethylenically unsaturated polyisobutylene having a number average molecular weight between about 2000 and about 8000, the improvement which comprises a bulk free radically initiated process in which 20-50 parts by weight of a vinyl ester having the formula: ##EQU2## where R is a saturated hydrocarbon having from 9-19 carbon atoms, the carbon atom attached to the carboxyl function being tertiary or quaternary and 10-90 parts by weight of an α-alkenyl aromatic hydrocarbon having the formula: ##SPC2## having from 8 to 10 carbon atoms per molecule, where X is a methyl group or hydrogen, Y is a methyl group, and n is an integer from 0 to 2 inclusive in a calculated weight ratio of vinyl ester to α-alkenyl aromatic hydrocarbon of at least below 25:1 are brought to a temperature of about 150°C to about 200°C in the presence of a catalytic amount of free radical initiator with a half lifetime of at least 0.4 hours at 150°C and the polymerization temperature maintained in the 150° to 200°C range by the combination of heating, cooling and retarding the polymerization by the gradual addition of α-alkenyl aromatic hydrocarbon together with a catalytic amount of said free radical initiator over a 4-24 hour period.