Process and device for producing coated moldings

A batch process for producing moldings comprising a layer of polyurethane on a substrate comprising:

• a) mixing reactive polyurethane-forming components in a cylindrical mixing chamber to form a batch of a reactive mixture,
• b) guiding the reactive mixture from the mixing chamber to the substrate through an admission opening into a flow channel,
• c) guiding a stream of gas from the region of the admission opening into the flow channel,
• d) spraying the reactive mixture leaving the flow channel onto the surface of the substrate,
• e) allowing the reactive mixture on the surface of the substrate to cure,
• f) mechanically cleaning the mixing chamber by moving an ejector which is movable axially in the mixing chamber from batch position into cleaning position when spraying of the batch has been completed, and
• g) maintaining the ejector in the cleaning position until both the ejector's end face and the flow channel have been cleaned by the stream of gas.