Retortable plastic container having improved base stability

Abstract

A retortable plastic container includes a main body and a bottom. The bottom defines a raised inner portion and at least one substantially flat bottom support surface. The substantially flat bottom support surface is curved and positioned near a radially outermost edge of the bottom when viewed in bottom plan. A groove is defined in the substantially flat bottom support surface. In addition, a first side wall portion that extends upwardly from the radially outermost edge of the bottom is shaped as a truncated cone, giving the bottom portion greater dimensional stability under retort conditions. The container bottom exhibits superior dimensional stability with respect to predecessor designs.

What is claimed is: 
     
         1 . A retortable plastic container, comprising:
 a main body; and   a bottom;   the bottom defining a raised inner portion and at least one substantially flat bottom support surface that is curved and positioned near a radially outermost edge of the bottom when viewed in bottom plan, and further comprising a groove defined in the substantially flat bottom support surface.   
     
     
         2 . A retortable plastic container according to  claim 1 , wherein the groove is substantially concentric with respect to the curvature of the substantially flat bottom support surface. 
     
     
         3 . A retortable plastic container according to  claim 1 , wherein the bottom is fabricated from a material comprising polypropylene. 
     
     
         4 . A retortable plastic container according to  claim 1 , wherein the retortable plastic container is fabricated using an extrusion blow molding process. 
     
     
         5 . A retortable plastic container according to  claim 4 , wherein the plastic container has a mold parting line as a result of the extrusion blow molding process, wherein the substantially flat bottom support surface extends continuously around a periphery of the bottom, and wherein a pair of opposed tunnel recesses are defined in the substantially flat bottom support surface in the area of the mold parting line. 
     
     
         6 . A retortable plastic container according to  claim 1 , wherein the substantially flat bottom support surface has a width, and wherein the retortable plastic container has a maximum outer diameter, and wherein a ratio of the width to the maximum outer diameter is substantially within a range of about 0.035 to about 0.2. 
     
     
         7 . A retortable plastic container according to  claim 6 , wherein the ratio of the width to the maximum outer diameter is substantially within a range of about 0.0425 to about 0.01. 
     
     
         8 . A retortable plastic container according to  claim 7 , wherein a ratio of the width to the maximum outer diameter is substantially within a range of about 0.05 to about 0.008. 
     
     
         9 . A retortable plastic container according to  claim 1 , wherein the groove has a curved inner surface having a maximum width, and wherein the substantially flat bottom support surface has a width, and wherein a ratio of the maximum width of the groove to the width of the support surface is substantially within a range of about 0.1 to about 0.9. 
     
     
         10 . A retortable plastic container according to  claim 9 , wherein the ratio of the maximum width of the groove to the width of the support surface is substantially within a range of about 0.25 to about 0.75. 
     
     
         11 . A retortable plastic container according to  claim 10 , wherein the ratio of the maximum width of the groove to the width of the support surface is substantially within a range of about 0.40 to about 0.6. 
     
     
         12 . A retortable plastic container according to  claim 1 , wherein the groove has a curved inner surface having an average radius of curvature and wherein the substantially flat bottom support surface has a width, and wherein a ratio of the average radius of curvature to the width of the support surface is substantially within a range of about 0.05 to about 1.0. 
     
     
         13 . A retortable plastic container according to  claim 12 , wherein the ratio of the average radius of curvature to the width of the support surface is substantially within a range of about 0.25 to about 0.75. 
     
     
         14 . A retortable plastic container according to  claim 13 , wherein the ratio of the average radius of curvature to the width of the support surface is substantially within a range of about 0.40 to about 0.6. 
     
     
         15 . A retortable plastic container according to  claim 1 , wherein the groove has a maximum depth and wherein the support surface has a width, and wherein a ratio of the maximum depth of the groove to the width of the support surface is substantially within a range of about 0.01 to about 0.3. 
     
     
         16 . A retortable plastic container according to  claim 15 , wherein the ratio of the maximum depth of the groove to the width the support surface is substantially within a range of about 0.03 to about 0.2. 
     
     
         17 . A retortable plastic container according to  claim 16 , wherein the ratio of the maximum depth of the groove to the width of the support surface is substantially within a range of about 0.05 to about 0.15. 
     
     
         18 . A retortable plastic container according to  claim 1 , wherein the groove has a maximum depth and wherein an outermost edge of the support surface is convex and has an average radius of curvature, and wherein a ratio of the average radius of curvature of the outermost edge to the maximum depth of the groove is substantially within a range of about 0.5 to about 10. 
     
     
         19 . A retortable plastic container according to  claim 18 , wherein the ratio of the average radius of curvature of the outermost edge to the maximum depth of the groove is substantially within a range of about 0.75 to about 5. 
     
     
         20 . A retortable plastic container according to  claim 19 , wherein the ratio of the average radius of curvature of the outermost edge to the maximum depth of the groove is substantially within a range of about 1.0 to about 3.0. 
     
     
         21 . A retortable plastic container according to  claim 1 , wherein the groove has a curved inner surface having an average radius of curvature and wherein the sidewall has an average thickness, and wherein a ratio of the average thickness to the average radius of curvature is substantially within a range of about 0.5 to about 2.0. 
     
     
         22 . A retortable plastic container according to  claim 21 , wherein the ratio of the average thickness to the average radius of curvature is substantially within a range of about 0.7 to about 1.8. 
     
     
         23 . A retortable plastic container according to  claim 22 , wherein the ratio of the average thickness to the average radius of curvature is substantially within a range of about 0.9 to about 1.6. 
     
     
         24 . A retortable plastic container according to  claim 1 , wherein the groove has a maximum width and wherein the sidewall has an average thickness, and wherein a ratio of the average thickness to the maximum width is substantially within a range of about 0.1 to about 1.0. 
     
     
         25 . A retortable plastic container according to  claim 24 , wherein the ratio of the average thickness to the maximum width is substantially within a range of about 0.2 to about 0.85. 
     
     
         26 . A retortable plastic container according to  claim 25 , wherein the ratio of the average thickness to the maximum width is substantially with a range of about 0.3 to about 0.65. 
     
     
         27 . A retortable plastic container according to  claim 1 , wherein the container further comprises a first side wall portion extending upwardly from the radially outermost edge, and wherein the first side wall portion is substantially straight when viewed in longitudinal cross-section. 
     
     
         28 . A retortable plastic container according to  claim 27 , wherein the first side wall portion defines an angle with respect to a vertical axis that is substantially within a range of about 0° to about 15°. 
     
     
         29 . A retortable plastic container according to  claim 28 , wherein the first side wall portion defines an angle with respect to a vertical axis that is substantially within a range of about 0° to about 12°. 
     
     
         30 . A retortable plastic container according to  claim 29 , wherein the first side wall portion defines an angle with respect to a vertical axis that is substantially within a range of about 0° to about 8°. 
     
     
         31 . A retortable plastic container according to  claim 27 , wherein the first side wall portion is shaped substantially as a truncated cone. 
     
     
         32 . A retortable plastic container according to  claim 27 , further comprising a second side wall portion extending upwardly from the first side wall portion, and wherein the second side wall portion is connected to the first side wall portion by a concave fillet having an average radius of curvature. 
     
     
         33 . A retortable plastic container according to  claim 27 , wherein the first side wall portion has a maximum height, and wherein a ratio of the maximum height to a maximum outer diameter of the container is substantially within a range of about 0.015 to about 0.040. 
     
     
         34 . A retortable plastic container according to  claim 33 , wherein the ratio of the maximum height to the maximum outer diameter of the container is substantially within a range of about 0.020 to about 0.035. 
     
     
         35 . A retortable plastic container according to  claim 34 , wherein the ratio of the maximum height to the maximum outer diameter of the container is substantially within a range of about 0.025 to about 0.030. 
     
     
         36 . A retortable plastic container according to  claim 27 , further comprising a second sidewall portion that is connected to the first sidewall portion by a fillet having average radius of curvature, and wherein a ratio of the average radius of curvature to the maximum outer diameter of the container is substantially within a range of about 0.0045 to about 0.065. 
     
     
         37 . A retortable plastic container according to  claim 36 , wherein the ratio of the average radius of curvature to the maximum outer diameter of the container is substantially within a range of about 0.007 to about 0.04. 
     
     
         38 . A retortable plastic container according to  claim 37 , wherein the ratio of the average radius of curvature to the maximum outer diameter of the container is substantially within a range of about 0.0092 to about 0.02.