Wiped film devolatilization process

Claim 2

moved axially substantially completely through said zone within an average residence time of from about 10 to 1,000 sec., and

Claim 3

maintained at a temperature of from about 0 to 350*C. from energy supplied thereto in the form of thermal energy supplied through the circumferential walls of said zone and also in the form of mechanical energy dissipated in said dispersion by the action of said rotating blades thereon, said subjecting being accomplished while maintaining the ratio of the volume of non-vaporized dispersion in said zone to the total volume of said zone in the range of from about 0.01:1 to 0.5:1, C. moving in said zone said dispersion axially through said zone as a melt material and D. separating the resulting non-vaporized dispersion from said vapors evolved therefrom, said separating, said moving, and said subjecting being conducted while maintaining the absolute pressure in said zone generally at a value which is less than the value of the equilibrium partial pressure of said low molecular weight components in said resulting non-vaporized dispersion at the desired concentration of said low molecular weight components therein when said resulting non-vaporized dispersion is substantially within the region of said separation, the improvement which comprises: E. removing said separated volatiles from said zone during separation step D at a take-off port located in the downstream end of said zone, said take-off port being located so as to cause said volatiles to move axially and cocurrently through the zone with said dispersion in step C thereby minimizing foaming at said take-off port and eliminating degradation of the polymer providing efficient devolatilization of said dispersion.

Claim 4

The process of claim 2 wherein the separated said dispersion is reprocessed a second time by the sequence of steps comprising said introducing, said subjecting, said moving, said separating and said removing.

Claim 5

The process of claim 2 wherein said dispersion comprises from about 50 to 75 weight percent homopolystyrene, and, correspondingly, from about 25 to 50 weight percent styrene monomer.

Claim 6

The process of claim 2 wherein said dispersion comprises from about 50 to 75 weight percent styrene/acrylonitrile copolymer, and, correspondingly, from about 25 to 50 weight percent of a mixture of styrene and acrylonitrile monomers.

Claim 7

The process of claim 2 wherein said dispersion comprises from about 50 to 75 weight percent of a graft copolymer of styrene upon a preformed elastomeric substrate with the balance up to 100 weight percent comprising styrene monomer.

Claim 8

The process of claim 2 wherein said dispersion comprises from about 50 to 75 weight percent of a graft copolymer of styrene and acrylonitrile on a preformed elastomeric substrate, and, correspondingly, from about 25 to 50 weight percent of a mixture of styrene and acrylonitrile monomers.