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AssigneeContinental PET Technologies, Inc.
InventorsThomas E. Nahill, Suppayan M. Krishnakumar, Wayne N. Collette
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A method of reducing uncontrolled flow of a molten polymer during the packing and cooling stage of an injection molding cycle. A plurality of polymers are injected between a mold cavity and core for making a multilayer plastic article such as a preform, having an exterior layer of a first polymer and an interior layer of a second polymer. In a tapered region of the mold, a minimum width of the tapered region is selected to prevent the second polymer from developing an enhanced leading/trailing edge effect which causes the second polymer to reverse flow during the packing and cooling stage. The method is particularly useful for making preforms for blow molded containers, such as a ketchup container, having a relatively long and thin neck profile. In addition, the method maintains the interior (barrier) layer a minimum distance from the top sealing surface of the preform, in order to prevent defective heat-bonded seals.
A method of reducing uncontrolled flow of a molten polymer during the packing and cooling stage of an injection molding cycle, wherein a plurality of polymers are injected between a mold cavity and core for making a multilayer plastic article having upper and lower regions and a tapered region there between which decreases in wall thickness as it approaches the upper region, wherein during the molding cycle at least one first polymer is injected to form an exterior layer and at least one second polymer is injected to form an interior layer, and wherein the second polymer forms a flow front having a leading/trailing edge, the method comprising the step of:
A method of reducing uncontrolled flow of a molten polymer during the packing and cooling stage of an injection molding cycle, wherein a plurality of polymers are injected between a mold cavity and core for making a multilayer plastic preform having a neck finish, a tapered neck region which decreases in wall thickness as it approaches the neck finish, a sidewall and a base, wherein during the molding cycle at least one first polymer is injected to form an exterior layer and at least one second polymer is injected to form an interior layer, and wherein the second polymer forms a flow front having a leading/ trailing edge, the method comprising the step of:
In a method of molding a multilayer article in an injection mold wherein a first flow front of a first material precedes a second flow front of a second material and the first flow front has a leading/trailing edge, the improvement comprising:
In a method of molding a multilayer article in an injection mold wherein a first flow front of a first material precedes a second flow front of a second material, the improvement comprising:
In a method of molding a multilayer article in an injection mold, the article having an internal layer and a top sealing surface, the improvement comprising:
Dependencies are inferred from the claim text.