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US 6,294,637 B1Granted
Continuous preparation of melt-processable polyurethane in a twin screw extruder
AssigneeBayer Aktiengesellschaft
InventorsWolfgang Bräuer, Friedemann Müller, Jürgen Winkler, Herbert Heidingsfeld
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Abstract
The invention relates to a process for the continuous preparation of melt-processable polyurethanes, wherein an isocyanate-terminated prepolymer is intensively mixed with chain extender at temperatures of <200° C., and the mixture obtained is converted to melt processable polyurethane in a twin screw extruder under quasi-adiabatic reaction conditions.
Claims20
A process for continuously preparing a melt-processable polyurethane, the process comprising the steps of:
- A) intensively mixing an isocyanate-terminated prepolymer with a chain extender at a temperature of less than 200° C. to form a reaction mixture;
- and
- B) converting the reaction mixture to the melt-processable polyurethane in a twin screw extruder under quasi-adiabatic reaction conditions.
A process for continuously preparing a melt-processable polyurethane, the process comprising the steps of:
- A) intensively mixing an isocyanate-terminated prepolymer with a chain extender at a temperature of less than 200° C. to form a reaction mixture;
- and
- B) converting the reaction mixture to the melt-processable polyurethane in a twin screw extruder under quasi-adiabatic conditions;
- wherein the process further comprises:
- (i) determining a prescribed temperature profile for the reaction mixture in step B) by performing a trial run beforehand to obtain a product possessing desired properties;
- (ii) measuring an actual temperature profile of the reaction mixture in step B);
- (iii) comparing the actual temperature profile to the prescribed temperature profile;
- and
- (iv) adjusting reactivity of the reaction mixture in step B) by adjusting the actual temperature profile in step B), based on the comparison of the actual and prescribed temperature profiles, the actual temperature profile being adjusted by performing at least one of the following steps:
- adjusting the temperature and/or an amount of the reactants in step A);
- adjusting a temperature and/or an amount of the reaction mixture in step B);
- and
- adjusting a temperature and/or an amount of a catalyst which is used in the preparation of the melt-processable polyurethane.
10 more elements
Dependencies are inferred from the claim text.