Patent GB-1476703-A (GB)
Title: Continuous mass polymerization process
IPC: C08F279/02
Filed: 1975-03-06
Abstract: 1476703 Mass polymerization process MONSANTO CO 6 March 1975 [7 March 1974] 9295/75 Heading C3G A continuous mass polymerization process comprises (A) continuously mass polymerizing a formulation comprising at least principally (i) one or more monoalkenyl aromatic monomers, preferably having the formula wherein Ar is phenyl, halophenyl, alkylphenyl or haloalkylphenyl and X is H, CH 3  or C 2 H 5  wherein at least 20% by weight of monoalkenyl aromatic monomer is present and (ii) an ethylenically unsaturated nitrile in an amount of at least 5% by weight monomer, said formulation comprising 0À1-15% by weight, based on the monomer formulation of a diene rubber, soluble in the monomer formulation, so as to convert 10-40% by weight of the monomers of the formulation to polymer, to graft at least a portion of the monomers to the soluble diene rubber and to disperse this first grafted rubber as rubber-monomer particles of weight average particle diameter 0À7-10 microns comprising both grafted and occluded polymer in a monomer-polymer phase thereby providing a first partially polymerized mixture (B) continuously withdrawing the first partially polymerized mixture (C) continuously dispersing, in the first partially polymerized mixture, a second grafted diene rubber comprising cross-linked rubber particles of swelling index 2-10 a weight average particle diameter of 0À01-0À5 microns and being grafted with 0À1-2À5 parts by weight of the monomers of the formulation per part by weight of rubber, thereby providing a second partially polymerized mixture containing from 1-30% by weight of first and second grafted diene rubbers, the second grafted diene rubber comprising from 50-97% of the total weight of grafted diene rubber (D) continuously mass polymerizing the second partially polymerized mixture to a conversion of 25-80% by weight of the original monomers of the formulation thereby providing a third partially polymerized mixture (E) continuously devolatilizing the third partially polymerized mixture to provide a polymer blend comprising from 2-40 % by weight of first and second grafted diene rubbers, the first grafted diene rubber being dispersed as rubber particles of weight average particle diameter 0À7-10 microns and swelling index 2-40 and comprising both occluded and graft polymer in an amount of from 1-5 parts by weight of polymer per part of rubber, the second grafted diene rubber comprising from 50-97% by weight of the total weight of grafted diene rubbers, the remainder of the blend being polymer of the monomers of the formulation. The formulation in (A) and (D) may comprise 0À001-3À0% by weight, based on the weight of monomers, of a free-radical generating catalyst. Preferred rubbers are polybutadiene, poly- (butadiene - styrene), poly(butadiene - styreneacylonitrile), poly(butadiene - acrylonitrile), polyohloroprene, poly(chloroprene - butadiene), poly(chloroprene - styrene) poly(chloroprene - acrylonitrile) and poly(chloroprene - styrene - acrylonitrile). In the Examples, the second grafted diene rubber comprises a styrene and acrylonitrile monomer mixture grafted on to a butadiene/ acrylonitrile rubber latex which is dispersed in a grafted polymer solution obtained by polymerizing styrene and acrylonitrile in the presence of polybutadiene.