Container structure for removal of vacuum pressure

1. A plastic container having a longitudinal axis, and comprising: an upper portion including an opening into the container; a sidewall portion extending from the upper portion to a lower portion, the lower portion including a base; and a pressure panel located in the lower portion substantially transversely to the longitudinal axis, the pressure panel being movable substantially along the longitudinal axis between an initial position and an inverted position to compensate for a change of pressure induced within the container; wherein the pressure panel comprises a centrally located push-up portion adapted to move in response to a longitudinally directed force and cause the pressure panel to at least partially invert; wherein when in the initial position a control portion of the pressure panel defines an angle with respect to the longitudinal axis and the opening into the container that is greater than about 100 degrees; and wherein the push-up portion defines an angle of inclination with respect to the longitudinal axis and the opening into the container that is less than that of the control portion.

2. The container of claim 1 , wherein the pressure panel is adapted to move from the initial position to the inverted position under an externally applied mechanical force.

3. The container of claim 1 , wherein the pressure panel is adapted to move from the initial position to the inverted position in response to internal vacuum forces within the container.

4. The container of claim 1 , wherein the pressure panel includes an invertible portion defining an angle of outward inclination with respect to a plane orthogonal to the longitudinal axis that is less than the control portion.

5. The container of claim 4 , wherein the invertible portion is located closer to the longitudinal axis than is the control portion.

6. The container of claim 5 , wherein the invertible portion and the control portion define a substantially continuous curve when viewed in a cross-sectional plane extending through the longitudinal axis.

7. The container of claim 1 , wherein the pressure panel begins to invert first from the widest diameter, and further from the longitudinal axis.

8. The container of claim 7 , wherein the pressure panel comprises more than one initiator portion.

9. The container of claim 8 , wherein the pressure panel also comprises an invertible initiator portion located further from the longitudinal axis than the control portion.

10. The container of claim 8 , wherein the pressure panel comprises an initiator portion located adjacent to the push-up portion and closer to the longitudinal axis than the control portion.

11. The container of claim 10 , wherein the initiator portion defines an angle of inclination with respect to the longitudinal axis and the opening into the container that is less than the control portion.

12. The container of claim 1 , wherein when in the initial position, at least a portion of the pressure panel defines an angle of inclination with respect to a plane orthogonal to the longitudinal axis that is greater than about 15 degrees.

13. The container of claim 1 , further comprising a hinge structure connecting the pressure panel to the lower portion.

14. The container of claim 1 , further comprising a standing surface and an instep or recess between the pressure panel and the standing surface.

15. A plastic container having a longitudinal axis, and comprising: an upper portion including an opening into the container; a sidewall portion extending from the upper portion to a lower portion, the lower portion including a base; defining a standing surface; a pressure panel located in the lower portion substantially transversely to the longitudinal axis, the pressure panel being movable substantially along the longitudinal axis between an initial position and an inverted position to compensate for a vacuum pressure induced within the container; wherein when in the initial position, at least a portion of the pressure panel defines an angle of inclination with respect to a plane orthogonal to the longitudinal axis that is greater than about 15 degrees downwardly inclined away from the upper portion; an instep or recess between the pressure panel and the standing surface; a hinge connecting the pressure panel to the instep; and a centrally located push-up portion

wherein the portion defining an angle of inclination that is greater than about 15 degrees defines a control portion and the pressure panel moves from the initial position to the inverted position in response to internal vacuum forces developed within the container as a result of cooling of liquid contents within the container; and

wherein the pressure panel comprises at least one initiator portion and a control portion, the initiator portion including the centrally located push-up portion and being adapted to move in response to the internal vacuum forces and cause the control portion to invert.