DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0016] Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to FIG. 1, a retortable plastic container 10 that is constructed according to a preferred embodiment of the invention includes a finish portion 12 and a main body portion 14 that is unitary with the finish portion 12. Container 10 further includes a bottom portion 16 and a bottom transition portion 18 that is unitary with the bottom portion 16 and the main body portion 14. The entire container 10 is preferably fabricated from a multilayer plastic material having a first, inner layer of polypropylene, a second, adhesive layer, a third, barrier layer fabricated from a material such as EVOH, a fourth adhesive layer, a fifth layer of reground polypropylene and a sixth, outer layer of polypropylene. It should be understood that this material is provided as a preferred example only, and that the invention as described and claimed herein is equally applicable to a retortable plastic container that is fabricated from any one of a virtually infinite possible selection of plastic materials and laminates.

[0017] Referring now to FIG. 2, which is a magnified view of area 2-2 in FIG. 1, it will be seen that the sidewall 22 of container 10 preferably has an outer surface 24 and an inner surface 26. According to one particularly advantageous aspect of the invention, sidewall 22 is shaped so as to define at least one radially inwardly extending annular projection 20, the purpose of which is to provide reinforcement against radial expansion of the main body portion 14 of the container 10 during the retort process. Preferably, the inwardly extending annular projection 20, a cross-section of which is depicted in FIG. 4, is shaped so as to have an inwardly extending corner 28 that is shaped so as to have a radius of curvature that is no more than 0.015 inches. Preferably, annular projection 20 also has a depth D_R that is preferably within a range of about 2.0 to about 7.0 percent of a maximum matter radius R_MAX of the container 10, and is most preferably about 4.0 percent. Inwardly extending corner 28 preferably is shaped so as to have an angle α that is between 80 degrees and 100 degrees, and that is more preferably approximately 90 degrees.

[0018] Referring now to FIG. 5, it will be seen that according to another advantageous aspect of the invention bottom transition portion 18 has at least one inwardly radiused annular step, which provides increased rigidity against expansion to the lower portion of the container 10. In the preferred embodiment, a first inward step 30 is defined by a first concave radius R₁ that is defined on the inner surface 26 of the sidewall 22 and a second concave radius R₂ that is defined on the outer surface 24. A second inward step 30 is defined by a third concave radius R₃ on the inner surface 26 and a fourth concave radius R₄ on the outer surface 24. A fifth radius R₁ on the inner surface 26 completes the transition to the bottom portion 16 of the container 10.

[0019] Preferably, the radii that define the first and second steps 30, 32 have a radius of curvature that is no more than {fraction (3/8)}inch, and that is more preferably within a range of between about {fraction (1/32)} of an inch and ⅛ in an inch.

[0020] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.