Abstract: In one aspect, a method of coinjection molding a multilayer article using a coinjection nozzle having inner outlet, an outer outlet, and an intermediate outlet between the inner and outer outlets is provided. A stream of surface layer material is injected into a mold cavity from the intermediate outlet. With the injection ongoing, two streams of internal layer material are injected from the inner and outer outlets of the coinjection nozzle respectively. The two streams sandwich the stream of surface layer material and flow behind a melt front of the surface layer material. The sandwiched stream of surface layer material continues to supply the melt front with surface layer material at least until the melt front nears a distal end of the mold cavity. The resultant article is substantially or entirely encapsulated by a skin of the surface layer material and contains a high proportion of internal layer material.

Abstract: In one aspect, a method of molding a multilayer article comprises causing a surface layer material injection unit to commence injecting a surface layer material into a mold cavity via a surface layer material channel. Then, an internal layer material injection unit commences injecting an internal layer material into the mold cavity an internal layer material channel. Then, during application of a hold pressure upon the surface layer material in the surface layer material channel and with the surface and internal layer material injection units in fluid communication with one another, a pullback stroke is effected at the internal layer material injection unit. After a delay interval, at least one physical parameter indicative of a post-pullback pressure of the internal layer material is detected, and an indicator of pullback effectiveness is generated based on the post-pullback pressure indicated by the at least one physical parameter relative to a threshold pressure.

Abstract: In one aspect, a method of coinjection molding a multilayer article having a multi-segment internal layer is disclosed. A surface layer material is injected into a mold cavity from at least one of an inner outlet and an outer outlet of a multi-channel nozzle. An internal layer material is intermittently injected into the mold cavity from an intermediate outlet of the multi-channel nozzle that is between the inner and outer outlets. The intermittent injecting of the internal layer material is controlled, at least in part, by intermittent opening and closing of the intermediate outlet. An apparatus for coinjection molding the multilayer article with the segmented internal layer is also disclosed.