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AssigneeBayer Aktiengesellschaft
InventorsClaus Wulff, Gottfried Zaby, Clemens Casper, Klemens Kohlgruber, Thomas Bamberger, Hugo Obermann
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This invention relates to a process for producing granulated polymer materials from polymer solutions, in which organic solvent of the polymer solution is evaporated in a heat exchanger, optionally with the admixture of steam, or in a holding tube with the admixture of steam, and the paste-like mixture of concentrated solution, solvent vapour and optionally of condensed steam is separated in a separator provided with rotating built-in components for cleaning off the walls. The pre-concentrated polymer solution is further concentrated in the separator by supplying heat by way of heating the separator walls or the rotating built-in components and by the shearing energy of the rotating built-in components. Residual degassing of the solvent is effected before granulation, e.g. in the discharge extruder of the separator which is provided with rotating built-in components, through one or more degassing zones, optionally by the additional admixture of entraining media, such as inert gas or steam, for example.
A process for producing granulated polymer materials from polymer solutions of thermoplastic polymers by pre-concentration of the polymer solution by means of heat exchange or stripping the solvent with steam in a holding tube or a heat exchanger to form concentrated polymer solution or paste, further concentration and drying in a drying apparatus, extrusion and granulation of the dried polymer, wherein the polymer solution, with a polymer concentration of 3 to 30% by weight in an organic solvent, is heated to 50.degree. to 300.degree. C. under a pressure of 1 to 15 bar in one or more heat exchangers, the total heat exchange surface of which is 0.02 m.sup.2 /100 kg/hr solvent to 2 m.sup.2 /100 kg/hr solvent, or is heated by mixing with superheated steam at a solvent to steam ratio of .gtoreq.10:1 in a heated or unheated holding tube having a length to diameter ratio of 100 to 10,000, or is heated by mixing with steam at a temperature of 100.degree. to 300.degree. C. and at a pressure of 1 to 100 bar in a heat exchanger, the heat exchange surface of which is 0.02 m.sup.2 /100 kg/hr solvent to 2 m.sup.2 /100 kg/hr solvent, and the mixture heated in this manner is separated by flashing into a separator with separation of the vapours to form a concentrated polymer solution or paste with a concentration of 25 to 80% by weight of the concentrated paste or solution with respect to the polymer,
Dependencies are inferred from the claim text.