Base for hot-fill plastic containers

1. A base structure for a blow-molded container having an annular sidewall and a central longitudinal axis, the base structure comprising:

a bottom portion, having a flat outer surface;

a wedge-shaped annular support heel positioned between the sidewall and the bottom portion, wherein the wedge-shaped annular support heel is angled linearly and inwardly at an angle θ of from about 45° to about 65° relative a plane extending from the sidewall;

a plurality of partial sphere structures extending from the wedge-shaped annular support heel and beyond the bottom portion thus forming a spherical contact surface supporting the container; and

a rounded edge between the wedge-shaped annular support heel and the bottom portion, wherein the rounded edge has a radius of curvature of from about 1.0 mm to about 14.0 mm,

wherein the blow-molded container comprises a material selected from the group consisting of a polyester resin and polypropylene.

2. The base structure of claim 1 wherein the material is the polyester resin and is selected from the group consisting of poly(ethylene)terephthalate (PET), homopolymers of poly(ethylene)-phthalate, copolymers of poly(ethylene)terephthalate, poly(ethylene)isophthalate, poly(ethylene)naphthalate, poly(dimethylene)terephthalate, and poly(butylene)terephthalate.

3. The base structure of claim 1 wherein the rounded edge has a radius of curvature of from about 1.5 mm to about 6.0 mm.

4. The base structure of claim 3 wherein the rounded edge has a radius of curvature of from about 2.0 mm to about 4.0 mm.

5. The base structure of claim 1 wherein the material is polypropylene.

6. The base structure of claim 1 wherein the base remains substantially un-deformed when the blow-molded container is filled with a liquid and sealed and subjected to a thermal process comprising heating the container to a temperature of from about 98° C. to about 127° C. for about 10 to about 40 minutes followed by cooling to about from 25° C. to about 37° C. in from about 10 minutes to about 30 minutes, such that the blow-molded container does not lean more than 1° relative to the central longitudinal axis.

7. The base structure of claim 6 wherein the base remains substantially un-deformed when the blow-molded container is filled with a liquid and sealed and subjected to a thermal process comprising heating the container to a temperature of from about 108° C. to about 113° C. for about 20 to about 25 minutes followed by cooling to about 37° C. in from about 25 minutes to about 30 minutes, such that the blow-molded container does not lean more than 1° relative to the central longitudinal axis.

8. The base structure of claim 7 wherein the container experiences an internal pressure buildup of from about 0.1 bar to about 1.2 bar during heating.

9. The base structure of claim 7 wherein the container does not lean relative to the central longitudinal axis when the blow-molded container is subjected to the thermal process.

10. The base structure of claim 9 wherein the container experiences an internal pressure buildup of from about 0.1 bar to about 1.2 bar during heating.

11. The base structure of claim 6 wherein the container experiences an internal pressure buildup of from about 0.1 bar to about 1.2 bar during heating.

12. The base structure of claim 6 wherein the container does not lean relative to the central longitudinal axis when the blow-molded container is subjected to the thermal process.

13. The base structure of claim 12 wherein the container experiences an internal pressure buildup of from about 0.1 bar to about 1.2 bar during heating.

14. A base structure for a blow-molded container having an annular sidewall and a central longitudinal axis, the base structure comprising:

a bottom portion having a flat outer surface;

a wedge-shaped annular support heel positioned between the sidewall and the bottom portion, wherein the wedge-shaped annular support heel is angled linearly and inwardly at an angle θ of from about 45° to about 65° relative a plane extending from the sidewall;

a rounded edge between the wedge-shaped annular support heel and the bottom portion, wherein the rounded edge has a radius of curvature of from about 1.0 mm to about 14.0 mm; and

a plurality of partial sphere structures extending from the wedge-shaped annular support heel and beyond the bottom portion thus forming a spherical contact surface supporting the container,

wherein the blow-molded container comprises poly(ethylene)terephthalate (PET).

15. The base structure of claim 14 wherein the base remains substantially un-deformed when the blow-molded container is filled with a liquid and sealed and subjected to a thermal process comprising heating the container to a temperature of from about 98° C. to about 127° C. for about 10 to about 40 minutes followed by cooling to about from 25° C. to about 37° C. in from about 10 minutes to about 30 minutes, such that the blow-molded container does not lean more than 1° relative to the central longitudinal axis.

16. The base structure of claim 14 wherein the base remains substantially un-deformed when the blow-molded container is filled with a liquid and sealed and subjected to a thermal process comprising heating the container to a temperature of from about 108° C. to about 113° C. for about 20 to about 25 minutes followed by cooling to about 37° C. in from about 25 minutes to about 30 minutes, such that the blow-molded container does not lean more than 1° relative to the central longitudinal axis.

17. The base structure of claim 14 wherein the container experiences an internal pressure buildup of from about 0.1 bar to about 1.2 bar during heating.

18. The base structure of claim 14 wherein the container does not lean relative to the central longitudinal axis when the blow-molded container is subjected to the thermal process.