Gas impermeability for injection molded containers

Abstract

A molded multi-layer article has an interior layer contained within inner and outer layers. The article is molded by co-injecting the inner, outer, and interior layer materials into a mold defining a cavity. The interior layer material is caused to flow along a steam line offset from the zero velocity gradient of the combined material flow in a manner so that the interior layer material flow stream does not flow along or cross the zero velocity gradient yet has a greater flow velocity than the average flow velocity of the combined flow front. These methods and apparatus can mold four or more multilayer articles at once, each having an interior layer extending throughout 95% or more of the sealable portion of the article. The interior layer of a resultant article can extend throughout 99% or more of the sealable portion of the article.

1 - 21 . (canceled) 
     
     
         22 . A co-injection molding apparatus comprising:
 a mold defining a plurality of at least four cavities, wherein each of the plurality of cavities corresponds to one of a plurality of resulting symmetrical multi-layer articles;   a plurality of nozzle assemblies, wherein each of the plurality of nozzle assemblies corresponds to one of the plurality of cavities, wherein each of the plurality of nozzle assemblies is configured to inject a first polymeric material into the corresponding one of the plurality of cavities to form an interior layer of one of the plurality of resulting symmetrical multi-layer articles, and to inject a second polymeric material into the corresponding one of the plurality of cavities to form an inner layer and an outer layer of one of the plurality of resulting symmetrical multi-layer articles; and   a processor programmed to execute instructions to cause the first polymeric material to flow throughout the mold to provide each of the plurality of resulting symmetrical multi-layer articles with an interior layer that extends through at least 95% of a sealable portion.   
     
     
         23 . A co-injection molding apparatus as defined in  claim 22 , wherein the processor is further programmed to execute instructions to maintain a flow stream of the first polymeric material offset from a zero velocity gradient of a combined material flow throughout each of the plurality of cavities. 
     
     
         24 . A co-injection molding apparatus as defined in  claim 22 , wherein each of the plurality of nozzle assemblies are configured to maintain a flow stream of the first polymeric material offset from a zero velocity gradient of a combined material flow throughout the corresponding one of the plurality of cavities. 
     
     
         25 . A co-injection molding apparatus as defined in  claim 22 , wherein the processor is further programmed to execute instructions to cause the first polymeric material to flow through each of the plurality of cavities at a greater velocity than an average velocity of the combined material flow. 
     
     
         26 . A co-injection molding apparatus as defined in  claim 22 , wherein the plurality of nozzle assemblies are further configured to cause the first polymeric material to flow through each of the plurality of cavities at a greater velocity than an average velocity of the combined material flow. 
     
     
         27 . A co-injection molding apparatus as defined in  claim 22 , wherein each of the plurality of cavities is substantially symmetric. 
     
     
         28 . A co-injection molding apparatus comprising a mold defining a mold cavity, the molding apparatus comprising:
 a nozzle assembly configured to inject a first polymeric material into a first mold cavity configured to form an interior layer of a first resulting symmetrical multi-layer article and inject a second polymeric material into the first mold cavity to form an inner and outer layer of the first resulting symmetrical multi-layer article; and   a processor programmed to execute instructions to cause the first polymeric material to flow throughout the first mold cavity to provide the first resulting symmetrical multi-layer article with an interior layer extending through at least 99% of a sealable portion of the first resulting symmetrical multi-layer article.   
     
     
         29 . A co-injection molding apparatus as defined in  claim 28 , wherein the processor is further programmed to execute instructions to maintain a flow stream of the first polymeric material offset from a zero velocity gradient of a combined material flow throughout the first mold cavity. 
     
     
         30 . A co-injection molding apparatus as defined in  claim 29 , wherein the nozzle assembly is configured to maintain the offset. 
     
     
         31 . A co-injection molding apparatus as defined in  claim 28 , wherein the processor is further programmed to execute instructions to cause the first polymeric material to flow through the first mold cavity at a greater velocity than an average velocity of the combined material flow. 
     
     
         32 . A co-injection molding apparatus as defined in  claim 28 , wherein the first mold cavity is substantially symmetric. 
     
     
         33 . A co-injection molding apparatus as defined in  claim 28   wherein the mold defines a plurality of cavities, wherein each of the plurality of cavities corresponds to one of a plurality of resulting symmetrical multi-layer articles;   wherein the nozzle assembly comprises a plurality of nozzle assemblies, wherein each of the plurality of nozzle assemblies corresponds to one of the plurality of cavities,
 wherein each of the plurality of nozzle assemblies is configured to inject the first polymeric material into the corresponding one of the plurality of cavities to form an interior layer of one of the plurality of resulting symmetrical multi-layer articles, 
 wherein each of the plurality of nozzle assemblies is further configured to inject the second polymeric material into the corresponding one of the plurality of cavities to form an inner layer and an outer layer of one of the plurality of resulting symmetrical multi-layer articles; and 
   wherein the processor is further programmed to execute instructions to cause the first polymeric material to flow throughout the plurality of cavities to provide an interior layer of each of the plurality of resulting symmetrical multi-layer articles that extends through at least 99% of a sealable portion.   
     
     
         34 - 50 . (canceled)