US20130213980A1

US20130213980A1 - Plastic container with flexible base

Info

Publication number: US20130213980A1
Application number: US13/841,363
Authority: US
Inventors: Marc Pedmo; Richard C. Darr
Original assignee: Plastipak Packaging Inc
Current assignee: Plastipak Packaging Inc
Priority date: 2008-12-31
Filing date: 2013-03-15
Publication date: 2013-08-22

Abstract

A plastic container is disclosed that includes a sidewall portion and a base portion. In embodiments, the base portion includes a flexible base portion configured for a first position, a second position, and a third position in response to internal forces associated with filling and cooling of container contents. The first position is a position following formation or molding, and prior to filling; the second position is a position during or following filling of contents at an elevated temperature, but before cooling or significant cooling of the contents, the second position is vertically lower than the first position; and the third position is a position after cooling of contents and vacuum forces associated with the contents have been substantially addressed, the third position is vertically higher than the first position.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent application Ser. No. 12/648,647, filed Dec. 29, 2009, currently pending, which claims the benefit of U.S. Provisional Application No. 61/141,812, filed Dec. 31, 2008. This application is also a continuation-in-part of U.S. patent application Ser. No. 12/702,370, filed Feb. 9, 2010 currently pending, which claims the benefit of U.S. Provisional Application No. 61/151,363, filed Feb. 10, 2009. This application additionally claims the benefit of U.S. Provisional Application No. 61/665,441, filed Jun. 28, 2012, and U.S. Provisional Application No. 61/716,932, filed Oct. 22, 2012. The entire contents of all of the foregoing applications are incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present disclosure generally relates to the field of plastic containers, including plastic containers, which may be lightweighted, and employ features to accommodate pressurization and/or hot-fill conditions.

BACKGROUND

Currently a significant number of plastic containers are filled with liquids and other contents at elevated temperatures. However, as the product or contents within the container cools, the volume taken up by the product or contents decreases, which can lead to the creation of vacuum forces within the container. Containers that are intended to be filled by a “hot-fill” process are commonly referred to as hot-fill containers. The design of hot-fill containers is influenced by, among other things, a desire to account for anticipated product or content cooling/shrinkage and associated forces. There is also an active interest in the industry to lightweight such containers without sacrificing desired function.

SUMMARY

A plastic container is disclosed that includes a sidewall portion and a base portion. Plastic containers in accordance with the teachings of the disclosure may be made of comparatively lighter weights (or “lightweighted”), and further may be configured to address internal vacuum forces in a desired manner. In embodiments, the container may be configured to create a greater/expanded differential to provide increased vacuum absorption.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings, wherein:

FIGS. 1A through 1G generally illustrate left, top plan, front, right, bottom, rear, and perspective views, respectively, of an embodiment of a container formed in accordance with teachings of the present disclosure;

FIG. 2 is a cross-sectional side elevation view generally representing an embodiment of a base of a plastic container shown in three different positions;

FIGS. 3, 4, and 5 generally illustrate a partial cross-sectional view of an embodiment of a base portion in a first, second, and third position, respectively.

FIG. 6 is a partial cross sectional representation of an embodiment of a base illustrating certain features associated with a flexible base portion.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the present disclosure, examples of which are described herein and illustrated in the accompanying drawings. While the invention will be described in conjunction with embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the disclosure and appended claims.
FIGS. 1A through 1G generally illustrate left, top plan, front, right, bottom, rear, and perspective views, respectively, of an embodiment of a container 10 formed in accordance with teachings of the present disclosure. As generally illustrated in FIG. 1A, embodiments of a plastic container 10 may include a sidewall 20 and a base 30. By employing teachings of the present disclosure a container, such as container 10, may be provided in the form of a lightweight container, or a further lightweighted form of container. That is, where an increased, or larger, displacement may be provided to accommodate vacuum forces, for embodiments associated sidewall portions may have a reduced thickness, thereby permitting reduced material weight, and/or increased “lightweighting.”
The container 10 may be comprised of one or more various polymers including, without limitation, polyethylene terephthalate (PET) and/or various other polymers commonly utilized with hot-fill-type plastic containers. In embodiments the container may also be biaxially oriented, which may be the result of, for example, a stretch blow-molding process. The invention is not, however, limited to the type or style of container shown, and various other sizes and configurations may come within the scope and spirit of the present disclosure.
An embodiment of a base 30 is generally illustrated in FIG. 2. The base 30 includes a flexible base portion 40 that is shown in a first base portion position (or first position) 42, a second base portion position (or second position) 44, and a third base portion position (or third position) 46. With an embodiment, the flexible base portion 40 may generally between the two points illustrated by the letter “P” in FIG. 2. However, the flexible base portion may have a smaller or larger comparative diameter to the diameter of the base than that shown and, if desired, the shape of the flexible base portion may be substantially symmetrical about a central vertical axis of the container. As generally illustrated, base 30 may include a segment S that extends generally from depicted point P to the bottom of the container.
With further reference to FIG. 2, the base portion 40 is illustrated in several positions that are generally associated with filling and cooling events. With reference to the view illustrated in FIG. 2, location/point(s) P (shown in the form of points given the partial cross sectional representation) may generally be configured to function as a hinge point (or hinge ring) for a section of the base portion 40. The first base portion position 42 generally depicts a first position that may follow formation or molding (e.g., blow molding), but is prior to filling the container with contents, such as a liquid at an elevated temperature. The second base portion position 44 generally depicts a second position that may occur during or following hot-filling of contents at an elevated temperature, but before cooling or significant cooling of the contents. A third base portion position 46 generally depicts a third position that may occur after cooling of internal contents and associated vacuum forces have been substantially addressed.
As generally illustrated in connection with the shift or transition of positions (i.e., from first position 42 to second position 44, and then to third position 46), the base portion 40 initially goes down. That is, following filling, the base portion 40 generally decreases in height above the support surface from first position 42 to second position 44. This movement or shift may be due, for instance, to the temperature of filled contents (such as a hot-filled liquid) and the associated hydrostatic pressure. Notably, this initial shift downward of the base portion 40 (e.g., to second position 44) can create or provide a greater “differential” (e.g., the internal spacial or volumetric difference between the second position and the third position). Such an increased or expanded differential can, for example, allow for greater vacuum absorption than if the base portion 40 were to remain in the first position 42 during/through hot-filling. With embodiments, the point P may generally remain essentially disposed in substantially the same position whether the base portion 40 is in a first position 42, a second position 44, or a third position 46.
FIGS. 3-5 generally illustrate a partial cross-sectional view of an embodiment of a base portion of a container (similar to that depicted in FIGS. 1A-1G) shown in a first, a second, and a third position, respectively. With reference to FIG. 1E and FIGS. 3-5, the base 30 may include an outer radial portion 48, which may further include a plurality of radial formations 50, and a central base portion 60 that is disposed radially inwardly of the outer radial portion 48 and radial formations 50. As generally illustrated in connection with FIGS. 3-5, during the movement of the flexible base portion 40, the outer radial portion 48 moves downwardly (see, e.g., the change in relative position from FIG. 3 to FIG. 4), and then moves significantly upwardly (see, e.g., the change in relative position from FIG. 4 to FIG. 5). With embodiments, the central base portion 60 may be configured to be fairly rigid and, as such, may be in substantially the same form throughout the aforementioned movement of the base portion 40 in response to internal pressure or vacuum forces. Various reinforcement formations and techniques may be included in central base portion to provide the desired degree of reinforcement.
With further reference to FIGS. 3-5, base 30 includes a segment S that generally extends between point P and the bottom of the container. For some embodiments, segment S may be designed or configured to flex or tilt (i.e., “give”) to a degree in response to pressures associated with the container 10 and/or movement of the flexible base portion 40. Such flex or tilt may, for instance, involve segment S tilting radially inward (the greater inward radial movement occurring generally at the upper portions of the segment S more near point P). Such flexing or tilting may, for example as generally illustrated in FIGS. 3 and 4, result in a slight increase in the angle between segment S and an imaginary perpendicular line extending upwardly from the bottom of segment S, as well as a slight vertical lowering of point P. The tilting of segment S may later be “reversed,” such as generally illustrated in connection with FIG. 5.
FIG. 6 generally illustrates a partial cross sectional representation of an embodiment of a base 30. As generally illustrated, the central base portion 60 of a base portion 40 may optionally include one or more catch features (which may also be referred to as “indents”) 70. Such catch features may, for example, serve to help keep the base portion 40 in a downward position when the container is removed from a mold. The catch features may include undercuts that are configured such that the plastic will blow down into them. With the inclusion of indents, when a container is blown, the plastic in the base is heated, which can cause the base to shrink upwardly. That in turn can cause the angle associated with the outer radial portion 48 to become relatively more flat (for example, more in the nature of the position shown in FIG. 5). The catch feature can serve to catch or arrest the associated plastic material so that as the material shrinks, the catch feature inhibits the ability to shrink upwardly locally. While three catch features 70 having a generally oval or kidney shape are shown in connection with the embodiment shown in FIG. 1E, more or less catch features may be provided, and further such features may be provided in various other sizes and shapes. For some embodiments, different catch features may be included and combined in a single base.
In embodiments, the volumetric displacement between the second position and the third position may be at least twice the volumetric displacement between the first and third position. Moreover, for some embodiments, the volumetric displacement between the second position and the third position may be at least three times the volumetric displacement between the first and third position. For example and without limitation, the differential between the first position 42 and third position 46 for a 20 fl. oz. container may be about 5 ml of potential volumetric displacement. However, by configuring the base portion 40 to shift to a second position 44 before vacuum absorption, the potential volumetric displacement (between the second position and the third position) may increase to about 17 ml.
Moreover, in contrast to some prior art containers, the base flexibility does not require additional mechanical assistance. Rather, the base portion 40 may be configured for movement from a first position 42 down to a second position 44 and then up to a third position 46 based entirely upon reaction to internal fill temperature and cooling effects. With such embodiments, no additional external equipment may be necessary to mechanically facilitate the movement of the base portion as such.
The base portion 40 may employ base configuration teachings such as those included in the teachings of U.S. patent application Ser. No. 12/648,647, which is incorporated herein in its entirety by reference, and may include portions configured to, among other things, move or flex in response to internal vacuum pressure/forces. In embodiments, the base 30 can be configured to accommodate nearly all or substantially all of the internal vacuum pressure or forces (particularly as compared to the sidewall portions of the container) that may be occasioned by or associated with the cooling of a hot-fill product or contents.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and various modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to explain the principles of the invention and its practical application, to thereby enable others skilled in the art to utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims

What is claimed is:

1. A plastic container comprising:

a sidewall portion; and

a base including a flexible base portion configured for a first position, a second position, and a third position in response to internal forces associated with filling and cooling of container contents;

wherein the first position is a position following formation or molding, and prior to filling; the second position is a position during or following filling of contents at an elevated temperature, but before cooling or significant cooling of the contents, the second position is vertically lower than the first position; and the third position is a position after cooling of contents and vacuum forces associated with the contents have been substantially addressed, the third position is vertically higher than the first position.

2. The plastic container of claim 1, wherein the flexible base portion includes a point configured to function as a hinge point for the first position, second position, and third position.

3. The plastic container of claim 2, wherein the point remains disposed in substantially the same position in the first position, the second position, and the third position.

4. The plastic container of claim 1, wherein the sidewall portion is configured to be rigid and substantially resist internal vacuum forces associated with the container.

5. The plastic container of claim 1, wherein the volumetric displacement between the second position and the third position is at least twice the volumetric displacement between the first and third position.

6. The plastic container of claim 1, wherein the volumetric displacement between the second position and the third position is at least three times the volumetric displacement between the first and third position.

7. The plastic container of claim 1, wherein, the plastic container is a plastic container configured to hold 20 fl. oz. and the differential between the first position and third position is about 5 ml of volumetric displacement, and the volumetric displacement between the second position and the third position is about 17 ml.

8. The plastic container of claim 1, wherein the container is comprised of polyethylene terephthalate (PET).

9. The plastic container of claim 1, wherein the container is biaxially oriented.

10. A method for filling a plastic container with a flexible base, the method comprising:

providing a plastic container including a flexible base portion configured in a first position;

filling the container with contents at an elevated temperature such that that base portion moves to a second position that is vertically lower than the first position;

permitting the container contents to cool such that the base portion moves to a third position that is vertically higher than the first position.

11. The method of claim 10, wherein the plastic container includes a sidewall portion that is configured to be rigid and substantially resist internal vacuum forces associated with the container.

12. The method of claim 10, wherein the volumetric displacement between the second position and the third position is at least twice the volumetric displacement between the first and third position.

13. The method of claim 10, wherein the volumetric displacement between the second position and the third position is at least three times the volumetric displacement between the first and third position.

14. The method of claim 10, wherein the flexible base portion moves from the second position to the third position without mechanical forces being imparted on the base portion.