Structure and method of sealing a closure assembly onto the neck finish of a plastic pressure container

Abstract

Plastic pressure container including a main body portion, a finish portion, and a closure assembly. The main body portion defines an interior space. The finish portion is unitary with the main body portion and defines a mouth in communication with the interior space. The finish portion has an inner surface, an outer surface and an upper rim proximate the mouth. The inner surface has an inner undercut defined therein proximate the upper rim. The outer surface has an outer undercut defined therein proximate the upper rim. The closure assembly is mounted to the finish portion in engagement with both the inner undercut and the outer undercut.

1 . A method of making a plastic pressure container, comprising:
 disposing a plastic material within a mold cavity configured to form a preform comprising:   a main body portion defining an interior space,   a finish portion unitary with the main body portion and defining a mouth in communication with the interior space, the finish portion having an inner surface, an outer surface and an upper rim proximate the mouth, the inner surface having an inner undercut defined therein proximate the upper rim, the inner undercut having a curved shape in cross-section, and the outer surface having an outer undercut defined therein proximate the upper rim, the outer undercut having a polygonal shape in cross-section, wherein the inner undercut defines a first depth relative to an inner diameter D 2  proximate the mouth and the outer undercut defines a second depth relative to an outer diameter D 3  proximate the mouth, the second depth being different than the first depth; and   inflating the main body portion of the preform to form a plastic pressure container.   
     
     
         2 . The method of  claim 1 , wherein the preform is formed by injection molding. 
     
     
         3 . The method of  claim 2 , wherein the plastic material comprises polyethylene terephthalate. 
     
     
         4 . The method of  claim 2 , wherein the plastic material comprises polyethylene naphthalate and/or polyethylene furanoate. 
     
     
         5 . The method of  claim 1 , wherein the method further comprises crystallizing the finish portion of the preform, and wherein crystallizing comprises supporting at least a part of the finish portion and applying heat to the finish portion. 
     
     
         6 . The method of  claim 1 , wherein the inner and outer undercuts extend substantially along an entire circumference of the finish portion. 
     
     
         7 . The method of  claim 1 , wherein the inner undercut defines an angle “a” relative to a vertical portion “y” of the inner surface, the angle “a” being between 10° and 50°. 
     
     
         8 . The method of  claim 1 , wherein the finish portion defines a longitudinal axis, and wherein at least one of the inner undercut and the outer undercut defines an engagement surface substantially perpendicular to the longitudinal axis. 
     
     
         9 . The method of  claim 8 , wherein the finish portion is configured for a closure assembly to be mounted thereon in engagement with both the inner undercut and the outer undercut. 
     
     
         10 . The method of  claim 9 , further comprising mounting a closure assembly to the plastic pressure container by crimping a first portion of the closure assembly to at least partially engage with the inner undercut, and crimping a second portion of the closure assembly to at least partially engage with the outer undercut. 
     
     
         11 . The method of  claim 10 , wherein the first portion of the closure assembly is an outer wall defined by an annular portion of the closure assembly, and the second portion of the closure assembly is a flange portion of the closure assembly. 
     
     
         12 . The method of  claim 11 , wherein the closure assembly is formed at least partially of metal. 
     
     
         13 . The method of  claim 1 , wherein container is configured to withstand aerosol pressurization within a range that is about 40-160 psi. 
     
     
         14 . A method of making a plastic pressure container, comprising:
 forming a preform by injection molding, the preform comprising:   a main body portion defining an interior space, and   a finish portion unitary with the main body portion and defining a mouth in communication with the interior space, the finish portion having an inner surface, an outer surface and an upper rim proximate the mouth, the inner surface having an inner undercut defined therein proximate the upper rim, the inner undercut having a curved shape in cross-section, and the outer surface having an outer undercut defined therein proximate the upper rim, the outer undercut having a polygonal shape in cross-section, wherein the inner undercut defines a first depth relative to an inner diameter D 2  proximate the mouth and the outer undercut defines a second depth relative to an outer diameter D 3  proximate the mouth, the second depth being different than the first depth;   crystallizing the finish portion of the preform, wherein crystallizing comprises supporting at least a part of the finish portion, and applying heat to the finish portion; and   inflating the main body portion of the preform within a mold cavity to form a plastic pressure container.   
     
     
         15 . The method of  claim 14 , wherein supporting at least a part of the preform finish portion includes supporting the preform inner undercut by inserting a plug into the preform mouth. 
     
     
         16 . A method of filling a plastic pressure container, comprising:
 providing a plastic container having   a main body portion defining an interior space, and   a finish portion unitary with the main body portion and defining a mouth in communication with the interior space, the finish portion having an inner surface, an outer surface and an upper rim proximate the mouth, the inner surface having an inner undercut defined therein proximate the upper rim, the inner undercut having a curved shape in cross-section, and the outer surface having an outer undercut defined therein proximate the upper rim, the outer undercut having a polygonal shape in cross-section, wherein the inner undercut defines a first depth relative to an inner diameter D 2  proximate the mouth and the outer undercut defines a second depth relative to an outer diameter D 3  proximate the mouth, the second depth being different than the first depth;
 mounting a closure assembly onto the finish portion in engagement with both the inner undercut and the outer undercut; and 
   filling the interior space with contents.   
     
     
         17 . The method of  claim 16 , wherein mounting comprises crimping a first portion of the closure assembly to at least partially engage with the inner undercut, and crimping a second portion of the closure assembly to at least partially engage with the outer undercut. 
     
     
         18 . The method of  claim 17 , wherein crimping the first portion and crimping the second portion occurs simultaneously. 
     
     
         19 . The method of  claim 16 , wherein the closure assembly is formed at least partially of metal. 
     
     
         20 . The method of  claim 16 , wherein the contents are filled at a pressure within a range that is about 40-160 psi.