A co-injection nozzle having a central injection channel with an open end and providing an injection path for injecting streams of melt materials to form a multi-layer article from the melt material streams. The nozzle comprises interfitting axially concentric members, including at least an interfitting...http://www.google.ca/patents/US5968558?utm_source=gb-gplus-sharePatent US5968558 - Apparatus for injection molding and injection blow molding multi-layer articles
