Polymeric material for container

Abstract

A vessel is configured to hold a product in an interior region formed in the vessel. The vessel is formed using a blow-molding process in which a multiple layer parison is blow molded to form the vessel. The multiple layer parison is formed in an extrusion process in which a number of extruders are arranged to co-extrude associated inner and outer parisons to establish the multiple layer parison.

1 . A method of producing a multilayer vessel, the method comprising the steps of
 extruding an inner-layer formulation and a core-layer formulation to form an inner parison and a core parison configured to have a core-parison density different than an inner-parison density of the inner parison,   aligning the inner parison and the core parison to cause the core parison to surround the inner parison and form a multilayer tube,   placing the multilayer tube in a mold cavity formed in a mold, and   expanding the multilayer tube to cause the multilayer tube to deform so that the core parison moves toward an inner surface of the mold and a multilayer vessel having an interior region formed therein is provided and to transform the core parison into a core layer having a core-layer density,   wherein a ratio of the core-layer density of the multilayer vessel to the core-parison density of the multilayer tube is in a range of about 1 to about 2.   
     
     
         2 . The method of  claim 1 , wherein a ratio of the core-layer density to the core-parison density is in a range of about 1.0 to about 1.25. 
     
     
         3 . The method of  claim 2 , wherein a ratio of the core-layer density to the core-parison density is in a range of about 1.0 to about 1.1. 
     
     
         4 . The method of  claim 3 , wherein a ratio of the core-layer density to the core-parison density is about 1. 
     
     
         5 . The method of  claim 2 , wherein the multilayer vessel has a vessel density, the multilayer tube has a tube density, and a ratio of the vessel density to the tube density is in a range of about 1.0 to about 1.9. 
     
     
         6 . The method of  claim 1 , wherein the multilayer vessel has a vessel density, the multilayer tube has a tube density, a ratio of the core-layer density to the core-parison density is in a range of about 1.0 to about 1.25, and a ratio of the vessel density to the tube density is in a range of about 1.0 to about 1.25. 
     
     
         7 . The method of  claim 6 , wherein the ratio of the vessel density to the tube density is about 1. 
     
     
         8 . The method of  claim 6 , wherein the core-layer formulation comprises a polyethylene. 
     
     
         9 . The method of  claim 8 , wherein the polyethylene is high density polyethylene (HDPE). 
     
     
         10 . The method of  claim 9 , wherein the HDPE is a HDPE hexene copolymer. 
     
     
         11 . The method of  claim 6 , wherein the core-layer formulation comprises one or more high density polyethylene base resins (HDPE). 
     
     
         12 . The method of  claim 11 , wherein the HDPE is unimodal. 
     
     
         13 . The method of  claim 12 , wherein the unimodal HDPE is a unimodal, high-melt strength HDPE. 
     
     
         14 . The method of  claim 13 , wherein the unimodal, high-melt strength HDPE is electron beam modified. 
     
     
         15 . The method of  claim 14 , wherein the electron beam modified unimodal, high-melt strength HDPE has long chain branching and a melt index of about 0.25 g/10 min. 
     
     
         16 . The method of  claim 6 , wherein the core-layer formulation comprises up to about 99.9% HDPE base resin. 
     
     
         17 . The method of  claim 16 , wherein the core-layer formulation comprises about 85% to about 99.99% HDPE base resin. 
     
     
         18 . The method of  claim 17 , wherein the core-layer formulation comprises a nucleating agent. 
     
     
         19 . The method of  claim 18 , wherein the nucleating agent is about 0.1% to 15% (w/w) of the core-layer formulation. 
     
     
         20 . The method of  claim 19 , wherein the core-layer formulation lacks talc. 
     
     
         21 . The method of  claim 19 , wherein the core-layer formulation lacks talc and further comprises a slip agent. 
     
     
         22 . The method of  claim 21 , wherein the slip agent is about 0% to 3% (w/w) of the core-layer formulation.