Method and apparatus for devolatilizing polymer solutions

Claim 3

A method as in claim 1 wherein the polymer in solution is selected from the group of thermoplastic poly­mers consisting of polystyrenes, polypropylenes, polycarbon­ates, polyphenylene ethers, polyetherimides, polyesters and polyamides.

Claim 4

A method as in claim 1 wherein the polymer solution is based within the zone of indirect heat exchange under a pressure of from about 2 to 200 atmospheres.

Claim 5

A method as in claim 1 wherein the polymer solution is heated within the zone of indirect heat exchange above the glass transition temperature of the polymers in solution.

Claim 6

A method as in claim 1 wherein the residence time of the polymer solution within said channels falls within the range of about 5 to 120 seconds.

Claim 7

A method as in claim 1 wherein the volatile components are evaporated at a pressure below 50 atmos­pheres.

Claim 8

A method as in claim 6 wherein the volatile components are evaporated under a vacuum.

Claim 9

A method as in claim 1 wherein the plurality of channels have a surface to volume ratio in the range of 5 to 30, a height of from 0.1 to 0.2 inches and a length of from 3 to 6 inches.

Claim 10

A method as in claim 8 wherein the polymer solution is heated to a temperature in the range of about 150°-350°C.

Claim 11

A method as in claim 9 wherein the residence time of the polymer solution within said channels falls within the range of 5 to 10 seconds.

Claim 14

A method as in claim 11 wherein the poly­styrene is selected from the group consisting of high impact polystyrene, acrylonitrile-butylene-styrene copolymer and brominated polystyrene.

Claim 15

A method as in claim 11 wherein the volatile components comprise styrene.

Claim 16

A method as in claim 13 wherein the polysty­rene solution additionally comprises a volatile solvent selected from the group consisting of toluene, benzene, xylene and ethylbenzene.

Claim 17

A method as in claim 11 wherein the polysty­rene solution contains another thermoplastic polymer select­ed from the group consisting of polyphenylene ethers, polycarbonates, polyetherimides, polybutylene terephthalates and polyethylene terephthalates.

Claim 18

A method as in claim 11 wherein the polymer solution is comprised of about 10 to 80% polystyrene and about 10 to 40% polypnenylene ether.

Claim 21

A method as in claim 17 wherein the volatile components are evaporated under a pressure below 50 atmos­pheres.

Claim 22

A devolatilization apparatus for separating at least 25% of the volatile components from a polymer solu­tion, said apparatus comprising: (A) a vessel having an inlet for the polymer solution, a vapor outlet for volatile components and an outlet for the devolatilized polymer solution and (B) a heat exchanger disposed within the vessel comprising (1) a central receiving zone for retaining polymer solution fed from the vessel inlet, (2) a plurality of channels surrounding the receiving zone which extend from the receiving zone to the outer periphery of the heat exchanger, said channels provid­ing heat exchange surfaces having a substantially uniform surface to volume ratio falling within the range of 4 to 50, a height of about 0.05 to 0.5 inches, and a length within the range of about 0.5 to 12 inches, (3) a means for heating the heat exchange surfaces to a temperature above the vaporization temperature of the volatile components and (4) a means for uniformly feeding said polymer solution into the channels.

Claim 23

A devolatilization apparatus for separating at least 25% of the volatile components from a polymer solu­tion, said apparatus comprising: (A) a vessel having an inlet for the polymer solution, a vapor outlet for volatile components and an outlet for the devolatilized polymer solution and (B) a heat exchanger disposed within the vessel comprising (1) a central receiving zone for retaining polymer solution fed from the vessel inlet, (2) a plurality of channels surrounding the receiving zone which extend from the receiving zone to the outer periphery of the heat exchanger, said channels provid­ing heat exchange surfaces having a substantially uniform surface to volume ratio falling within the range of 4 to 50, a height of about 0.05 to 0.5 inches, and a length within the range of about 0.5 to 12 inches, (3) a means for heating the heat exchange surfaces to a temperature above the vaporization temperature of the volatile components and (4) a means for uniformly feeding said polymer solution into the channels.

Claim 24

An apparatus as in claim 19 wherein the heat exchanger comprises over 50 channels.

Claim 25

An apparatus as in claim 19 wherein the heat exchanger comprises from about 200 to 10,000 channels.

Claim 26

An apparatus as in claim 19 wherein the channels are planar in configuration and have a rectangular cross-sectional area along their length.

Claim 27

An apparatus as in claim 19 wherein the channels have a height within the range of 0.1 to 0.2 inches and a width in the range of about 1 to 4 inches.

Claim 28

An apparatus as in claim 23 wherein the channel length falls within the range of about 1.25 to 6.0 inches.

Claim 29

An apparatus as in claim 19 wherein the heat exchanger and the central receiving zone for polymer solu­tion are cylindrical in configuration and the channels are disposed about their common central axis.

Claim 30

An apparatus as in claim 25 wherein the means for uniformly feeding the polymer solution into the channels comprises a pump which feeds the polymer solution into the central receiving zone assisted by a cylindrical spacer centrally disposed about the axis of the cylindrical heat exchanger within the central receiving zone for polymer solutions.

Claim 31

An apparatus as in claim 25 wherein the means for uniformly feeding the polymer solution into the channels comprises a pump which feeds the polymer solution into the central receiving zone assisted by a spacer, having either a conical or frusto-conical configuration centrally disposed about the axis of the cylindrical heat exchanger within the central receiving zone for polymer solutions.

Claim 32

An apparatus as in claim 25 wherein the channels increase in width as the distance from the zone for receiving polymer solution increases.

Claim 33

An apparatus as in claim 19 wherein the means for heating the heat exchange surfaces comprises a plurality of conduits for the circulation of heat exchange fluid, which interpenetrate the heat exchange surfaces.

Claim 34

An apparatus as in claim 22 wherein the heat exchanger is comprised of a plurality of stacked plates which define the central receiving zone for retaining the polymer solution and the plurality of channels.

Claim 35

An apparatus as in claim 30 wherein the means for heating the heat exchange surfaces comprises about 40 to 100 conduits which interpenetrate the stacked plates for the circulation of heat exchange fluid.

Claim 36

An apparatus as in claim 31 wherein the vessel has a height of from 2 to 4 times the height of the heat exchanger.