Process and device for producing plastic moldings from a flowable reaction mixture
AssigneeHennecke GmbH
InventorsHans-Michael Sulzbach, Reiner Raffel, Helmut Duschanek
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Abstract
Polyurethane molded articles are produced from a flowable polyol-polyisocyanate reaction mixture on a shot-wise basis. The flowable reaction mixture is formed by combining the components of that mixture in the mixing chamber of a mixhead. The contents of the mixhead are introduced (preferably via an outlet pipe) into a mold in a manner such that the mixing chamber is substantially emptied in each case. Any ambient gas in the mixing chamber is then removed before the respective next shot is initiated.
Claims12
A process for the production of a molded polyurethane article from a flowable polyol-polyisocyanate reaction mixture present in a mixing chamber comprising
- a) introducing the flowable reaction mixture into a mold in a manner such that the mixing chamber is substantially emptied,
- b) removing any ambient gas present in the mixing chamber after step a) has been completed but before step a) is repeated, and
- c) replacing the ambient gas removed in step b) with a gas that is soluble in the flowable reaction mixture.
A device useful the production of a molded polyurethane article by a shot process comprising:
- a) a mixhead having a mixing chamber with an inlet and outlet opening present therein,
- b) means for introducing reaction mixture components into the mixhead,
- c) means for conveying any content of the mixing chamber into a mold,
- d) a mold for receiving the contents of the mixing chamber,
- e) a gas outlet for the removal of ambient gas present in the mixhead after substantially all reaction mixture has been removed from the mixing chamber;
- and
- f) means for introducing gas into the mixhead after removal of the ambient gas.
Dependencies are inferred from the claim text.