Pressurizable container

Abstract

A container base that is capable of receiving positive internal pressure, such as that created by introducing liquefied gas during a hot filling process, includes either ribs that substantially connect to a standing ring or a draft surface formed on the bottom of the ribs, or a combination of such features.

We claim:  
     
         1 . A heat-set, pressurizable container suitable for filling at an elevated temperature, said container comprising: 
 a body;    an upper portion extending upwardly from the body and including a finish and an opening therein;    an enclosed base disposed below the body, said base including: 
 a standing ring on which the container rests;  
 a recess that extends inwardly and upwardly relative to the standing ring; and  
 plural ribs extending substantially inwardly from the recess, each one of the plural ribs including a lower portion that includes a draft surface extending inwardly and upwardly from the standing ring;  
 whereby (i) the draft surface deforms substantially downwardly in response to internal pressurization of the container, (ii) the container rests on the standing ring even after internal pressurization of the container, and (iii) the ribs resist eversion of the recessed base surface such that the container is capable of withstanding internal positive pressure.  
   
     
     
         2 . The container of  claim 1  wherein the container is formed of a heat-set plastic.  
     
     
         3 . The container of  claim 1  wherein the internal pressurization is formed by introducing a liquefied gas into the container prior to capping.  
     
     
         4 . The container of  claim 1  wherein the draft surface is substantially linear, in a first longitudinal cross section that is coplanar with a longitudinal centerline of the rib, while the container is in an unpressurized state.  
     
     
         5 . The container of  claim 4  wherein the draft surface is substantially planar while the container is in an unpressurized state.  
     
     
         6 . The container of  claim 4  wherein the draft surface is curved in a second longitudinal cross section that is perpendicular to the first longitudinal cross section.  
     
     
         7 . The container of  claim 1  wherein the draft surface is directly connected to the standing ring.  
     
     
         8 . The container of  claim 1  wherein each one of the plural ribs include a face surface that extends inwardly from the draft surface.  
     
     
         9 . The container of  claim 8  wherein draft surface includes a outer point proximate the standing ring and an inner point proximate the rib face, a line between the draft surface outer point and the draft surface inner point forming a draft angle relative to a horizontal line that is between approximately 0 degrees and 45 degrees.  
     
     
         10 . The container of  claim 9  wherein the draft angle is between about 3 degrees and about 40 degrees.  
     
     
         11 . The container of  claim 9  wherein the draft angle is between about 5 degrees and about 30 degrees.  
     
     
         12 . The container of  claim 9  wherein the draft angle is between about 5 degrees and about 15 degrees.  
     
     
         13 . The container of  claim 9  wherein the draft angle is between about 5 and 25 degrees.  
     
     
         14 . The container of  claim 9  wherein the draft angle is about 5 degrees.  
     
     
         15 . The container of  claim 9  wherein the draft surface is directly coupled to the standing ring proximate the draft surface outer point and is directly coupled to the rib face proximate the draft surface inner point, whereby the draft surface couples the standing ring and the rib face together.  
     
     
         16 . The container of  claim 9  wherein the standing ring defines a standing ring diameter and a standing ring land width, and the draft surface has a radial dimension of no more than approximately one-third the standing ring diameter minus four times the standing ring land width.  
     
     
         17 . The container of  claim 16  wherein the draft surface radial dimension is no more than approximately 80 percent of one-third the standing ring diameter minus four times the standing ring land width.  
     
     
         18 . The container of  claim 16  wherein the ribs have a depth measured proximate the draft surface that is at least the draft surface radial dimension divided by two times cosine of the draft angle.  
     
     
         19 . The container of  claim 16  wherein the ribs have a depth measured proximate the draft surface that is at least 1.2 times the draft surface radial dimension divided by two times cosine of the draft angle.  
     
     
         20 . The container of  claim 1  wherein the standing ring is substantially continuous and circumferential.  
     
     
         21 . The container of  claim 1  wherein the standing ring is circumferentially discontinuous.  
     
     
         22 . The container of  claim 21  wherein the standing ring is interrupted by the draft surface of the ribs.  
     
     
         23 . The container of  claim 1  wherein the standing ring has a width that is less than approximately 0.100 inches.  
     
     
         24 . The container of  claim 23  wherein the standing ring width is less than about 0.060 inches.  
     
     
         25 . The container of  claim 23  wherein the standing ring width is less than about 0.050 inches.  
     
     
         26 . The container of  claim 23  wherein the standing ring width is less than about 0.025 inches.  
     
     
         27 . The container of  claim 23  wherein the standing ring width is about 0.10 inches.  
     
     
         28 . The container of  claim 18  wherein the standing ring width no more than approximately four percent of standing ring diameter.  
     
     
         29 . The container of  claim 18  wherein the standing ring width no more than approximately three percent of standing ring diameter.  
     
     
         30 . The container of  claim 18  wherein the standing ring width no more than approximately two percent of standing ring diameter.  
     
     
         31 . The container of  claim 23  wherein the standing ring width is as small as the blow molding process will allow.  
     
     
         32 . The container of  claim 1  wherein the base further includes a heel extending upwardly from the standing ring toward the body.  
     
     
         33 . The container of  claim 32  wherein the heel is coupled to the base.  
     
     
         34 . The container of  claim 1  wherein the upper portion includes a dome from which the finish extends.  
     
     
         35 . The container of  claim 34  wherein the upper portion includes an elongated neck extending from the dome, the finish formed on the neck.  
     
     
         36 . The container of  claim 1  wherein the base further includes a heel that is coupled between the standing ring and the body, the standing ring defines a standing ring diameter, and the heel has a radial heel dimension that is no more than approximately 20 percent of the standing ring diameter.  
     
     
         37 . The container of  claim 36  wherein the heel radial dimension is at least approximately 10 percent of the standing ring diameter.  
     
     
         38 . The container of  claim 36  wherein the heel radial dimension is more than approximately 17.5 percent of the standing ring diameter.  
     
     
         39 . The container of  claim 38  wherein the heel radial dimension is at least approximately 15 percent of the standing ring diameter.  
     
     
         40 . The container of  claim 1  wherein the standing ring defines a standing ring diameter that is between approximately 60% and approximately 80% of a base diameter.  
     
     
         41 . The container of  claim 40  wherein the standing ring diameter between approximately 65% and approximately 70% of the base diameter.  
     
     
         42 . The container of  claim 1  wherein the internal pressurization is between approximately 15 and approximately 35 psi at hot fill temperatures.  
     
     
         43 . The container of  claim 1  wherein the internal pressurization is between approximately 0 and approximately 10 psi at ambient temperatures.  
     
     
         44 . The container of  claim 1  wherein said container is formed of a material having an intrinsic viscosity greater than approximately 0.75.  
     
     
         45 . A heat-set, pressurizable container suitable for filling at an elevated temperature, said container comprising: 
 a body;    an upper portion extending upwardly from the body and including a finish and an opening therein;    an enclosed base disposed below the body, said base including: 
 a standing ring on which the container rests;  
 a recess that extends inwardly and upwardly relative to the standing ring; and  
 plural ribs extending substantially inwardly from the recess, each one of the plural ribs including a lower portion that includes a draft surface extending inwardly and upwardly from the standing ring, the draft surface being directly coupled to the standing ring and forming a draft angle of between approximately 0 degrees and approximately 45 degrees, the draft surface is directly coupled to the standing ring proximate a draft surface outer point and is directly coupled to the rib face proximate a draft surface inner point, whereby the draft surface couples the standing ring and the rib face together.  
   
     
     
         46 . The container of  claim 44  wherein the draft angle is between about 3 degrees and about 40 degrees.  
     
     
         47 . The container of  claim 44  wherein the draft angle is between about 5 degrees and about 30 degrees.  
     
     
         48 . The container of  claim 44  wherein the draft angle is between about 5 degrees and about 15 degrees.  
     
     
         49 . The container of  claim 44  wherein the draft angle is about 5 degrees.  
     
     
         50 . The container of  claim 44  wherein the standing ring has a width that is less than approximately 0.100 inches.  
     
     
         51 . The container of  claim 44  wherein the standing ring width is less than about 0.075 inches.  
     
     
         52 . The container of  claim 44  wherein the standing ring width is less than about 0.050 inches.  
     
     
         53 . The container of  claim 44  wherein the standing ring width is less than about 0.025 inches.  
     
     
         54 . The container of  claim 44  wherein the standing ring width is less than about 0.10 inches.  
     
     
         55 . A method of filling a container with a flowable product, said method comprising: 
 providing a container comprising a body and a base, the base including: 
 a standing ring on which the container rests;  
 a recess that extends inwardly and upwardly relative to the standing ring; and  
 plural ribs extending substantially inwardly from the recess, each one of the plural ribs including a lower portion that includes a draft surface extending inwardly and upwardly from the standing ring;  
   introducing hot contents and liquefied gas into the container;    sealing the container before all of the liquefied gas vaporizes to create a positive internal pressure within the container;    whereby the draft surface deforms substantially downwardly in response to internal pressurization of the container, the container rests on the standing ring even after internal pressurization of the container, and the ribs resist eversion of the recessed base surface such that the container is capable of withstanding internal positive pressure.