Apparatus and method for producing solid polymeric material from a dilute polymer solution

Claim 1

In an apparatus for producing solid polymer from a polymer solution which contains about 5 - 50% by weight of solid polymer in about 50 - 95% by weight of a solvent, the combination which comprises: a. means for heating said polymer solution, and means for feeding it under pressure. b. a concentrator connected to accept said heated and pressurized solution as a feed solution, including a low pressure chamber portion into which the feed polymer solution is introduced, and a vent means for release of solvent vapor vaporized in said chamber, c. an extruder connected to receive the concentrated polymer solution from said concentrator, said concentrated polymer solution having a polymer content of about 30 - 80% by weight and about 70 - 20% by weight of solvent, d. vent means on said extruder upstream of said solution receiving connection for venting further solvent vapor from the concentrated polymer feed, e. counter-current fluid introducing means positioned downstream of the feed to said extruder and having connecting means for the introduction and flow of fluid counter-current to the movement of said concentrated polymer in said extruder, f. means on said extruder for removal of said fluid and of materials stripped from said concentrated polymer by said fluid, at a location upstream of the point of introduction of said counter-current fluid but downstream of the point of introduction of said concentrated polymer, and g. means at the extruder exit for controlling the back pressure of the polymer extruded from said extruder.