A device for manufacturing molded articles of plastics material which have an outer skin of a plastics material free of expanding agents and a porous core of a plastics material containing an expanding agent includes an extruder head with a main duct in communication with a discharge opening. Two feed...http://www.google.com.au/patents/US4789318?utm_source=gb-gplus-sharePatent US4789318 - Device for manufacturing molded articles of plastics material
