Polymer devolatilization
AssigneeThe Dow Chemical Company
InventorsJoseph P. Weller, Lawrence D. Wilson, Michele L. Rosenau, Pat Jimenez, Bernard M. Lescure
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Abstract
A process has been invented for removing contaminants (including solvent) from a flowing polymer, the process, in one aspect, including dissolving a sparingly soluble stripping agent into a flowing polymer, the sparingly soluble stripping agent stripping contaminants from the flowing polymer creating a mixture of contaminants and sparingly soluble stripping agent, which flows out from the flowing polymer, and separating the mixture from the polymer. In one aspect, recyclable sparingly soluble stripping agent is recovered and re-used.
Claims22
A process for removing contaminants from a flowing polymer, the process comprising:
- (a) making a flowing stream of polymer-solvent solution having an initial level of contaminants,
- (b) introducing the flowing stream of polymer-solvent solution and a sparingly soluble stripping agent with a Henry's constant of more than 500 atmospheres into a mixer,
- (c) applying a pressure of from 250 to 4500 psig to the mixer to form a polymer-solvent/sparingly soluble stripping agent mixture,
- (d) foaming under a vacuum the polymer-solvent/sparingly soluble stripping agent mixture, whereby a mixture of contaminants including solvent and sparingly soluble stripping agent is stripped from the polymer-solvent/sparingly soluble stripping agent mixture, and
- (e) separating the mixture of contaminants from the polymer-solvent/sparingly soluble stripping agent mixture to form a product polymer having a final level of contaminants,
- wherein the process is conducted at a temperature of from 150.degree. to 300.degree. C.
A process for removing contaminants from a flowing polymer, the process comprising
- (a) making a flowing polymer-solvent solution having an initial level of contaminants,
- (b) introducing the flowing stream of polymer-solvent solution and a sparingly soluble stripping agent with a Henry's constant of more than 500 atmospheres into a mixer, wherein the sparingly soluble stripping agent is broken into bubbles with a largest dimension equal to or less than 1 millimeter, to facilitate dissolution in the flowing stream of polymer-solvent solution, such as to produce a polymer-solvent/sparingly soluble stripping agent mixture,
- (c) foaming under a vacuum the polymer-solvent/sparingly soluble stripping agent mixture, whereby a mixture of contaminants including solvent and sparingly soluble stripping agent is stripped from the polymer-solvent/sparingly soluble stripping agent mixture, and
- (d) separating the mixture of contaminants from the polymer-solvent/sparingly soluble stripping agent mixture to form a product polymer having a final level of contaminants,
- wherein the process is conducted at a temperature of from 150.degree. to 300.degree. C.
A process for removing contaminants from a flowing polymer, the process comprising
- (a) making a flowing stream of polymer-solvent solution having an initial level of contaminants,
- (b) introducing the flowing stream of polymer-solvent solution and a sparingly soluble stripping agent into a mixer, such as to produce a polymer-solvent/sparingly soluble stripping agent mixture,
- (c) foaming under a vacuum the polymer-solvent/sparingly soluble stripping agent mixture, whereby a mixture of contaminants including solvent and sparingly soluble stripping agent is stripped from the polymer-solvent/sparingly soluble stripping agent mixture, and
- (d) separating the mixture of contaminants from the polymer-solvent/sparingly soluble stripping agent mixture to form a product polymer having a final level of contaminants which is at most 50 parts per million by weight,
- wherein the process is conducted at a temperature of from 150.degree. to 300.degree. C.
Dependencies are inferred from the claim text.