Patent GB-1476702-A (GB)
Title: Continuous mass polymerization process
IPC: C08L7/00
Filed: 1975-03-06
Abstract: 1476702 Mass polymerization and devolatilization process MONSANTO CO 6 March 1975 [7 March 1974] 9294/75 Heading C3G A continuous mass polymerization process comprises (A) continuously mass polymerizing a formulation comprising at least principally (i) one or more monoalkenylaromatic monomers, which preferably comprise at least one monomer of formula wherein Ar is phenyl, halophenyl, alkylphenyl, alkylhalophenyl and X is H, CH 3  or C 2 H 5 , wherein at least 20% by weight of monoalkenylaromatic monomer is present and (ii) an ethylenically unsaturated nitrile monomer in an amount of at least 5% by weight which mixture comprises 0À1-15% by weight, based on the weight of the monomer formulation of a diene rubber, soluble in the monomer formulation, so as to convert from 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 diene rubber as rubber-monomer particles of weight average particle diameter of 0À7- 10 microns comprising both occluded and grafted polymer, in a monomer-polymer phase thereby providing a first partially polymerized mixture (B) continuously with drawing the said first partially polymerised mixture (C) continuously mass polymerising the first partially polymerised mixture to a conversion of 25- 80% by weight of the monomers of the original formulation thereby providing a second partially polymerised mixture (D) continuously dispersing in the second partially polymerised mixture, a second grafted diene rubber comprising cross-linked rubber articles of swelling index 2-10, of 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 third partially polymerised mixture which contains 1-30% by weight of the first and second grafted diene rubbers, the second grafted diene rubber comprising 50- 97% of the weight of the total grafted diene rubbers (E) continuously devolatilizing said third partially polymerised mixture to provide a polymer blend comprising from 2-40% by weight of first and second grafted diene rubber, the first grafted diene rubber being dispersed as rubber particles of weight average particle diameter of 0À7-10 microns, of swelling index 2 to 40, and comprising both occluded and grafted polymer in an amount of 1-5 parts by weight of polymer per part by weight of rubber, the second grafted diene rubber comprising from 50-97% of the total weight of grafted diene rubbers, the remainder of the polymer blend being polymer of the monomers of the formulation. (A) and (C) may be initiated by 0À001-3À0%, based on the initial weight of monomers, of a free-radical generating catalyst. Preferred rubbers are polybutadiene, poly(butadienestyrene), poly(butadiene-styrene-acrylonitrile), polychloroprene, poly(chloroprene.butadiene), poly(chloroprene - styrene), poly(chloropreneacrylonitrile), and poly(chloroprene - styreneacrylonitrile). In the Examples, a monomer mixture of acrylonitrile and styrene is grafted on to a butadiene/acrylonitrile rubber which is dispersed in a grafted polymer obtained by polymerizing a monomer mixture of styrene and acrylonitrile in the presence of polybutadiene.