Hot-Fill Container Capable of Internal Pressurization
A container has features to enable it to withstand pressure filling, including a smooth transition between its sidewalls and vacuum panel, no vertical stiffeners on the edges of the vacuum panels, and a gripping portion having wall either with small radial components or oriented at oblique angles. A pair of windows are included in the field portion of the vacuum panel outside of the gripping portion.
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This application claims priority to Provisional Application No. 60/774,168, filed Feb. 16, 2006 and incorporated herein by reference in its entirety.
BACKGROUNDThis invention relates to containers and more particularly to containers suitable for hot filling with perishable foods or beverages.
Perishable foods, such as juices and soup, are often filled at an elevated temperature in a process generally referred to as “hot-fill.” In a typical hot-fill process, a perishable food or beverage is introduced into a plastic container at approximately 185° F. and a cap is applied to seal the container. Upon subsequent cooling of the contents, a negative pressure (that is, below atmospheric pressure) is formed within the container due to shrinkage of the contents. The container may also shrink upon being subjected to hot-filling temperatures, but the product contents generally shrink by a greater volumetric amount upon cooling than the decrease in container volume.
In order to withstand the temperatures common to hot-filling, containers typically are formed of a thermoplastic having a relatively high intrinsic viscosity and typically are heat treated. For example, a container may be formed in a heated blow mold, which is maintained at approximately 250° F. to 290° F. A container that is held in a heated blow mold undergoes a decrease in the orientation of the polymer and an increase in its crystallinity, which diminishes the distortion of the container when subjected to hot-fill temperatures.
Containers suitable for hot-filling applications typically are designed with vacuum panels formed in the container sidewall that flex in response to a decrease in internal pressure. For example, some plastic containers have several, equidistantly spaced vacuum panels that are configured to enable a circular label to be wrapped around the container. Land areas between the panels provide surfaces around which the label may be applied. Inward flexing of the vacuum panels in response to vacuum pressure prevent severe distortion of the land areas. Other plastic containers are configured to have opposing hand-grips that flex to absorb the internal vacuum. Flexing of the hand-grips in response to internal negative pressure prevents severe distortion of the surfaces to the front and to the rear of the hand-grips, which can receive labels.
Even though hot-fill containers are configured to function under internal vacuum conditions, the containers are sometimes subjected to positive internal pressure during the filling process. For example, some filling equipment subjects the container to internal positive pressure for a brief period. Containers having long stiffening ribs or other long stiff structures (such as structures having a large moment of inertia, in transverse cross section relative to the horizontal axis) may, in response to positive internal pressure, locally bulge outwardly in a kink. And the kink might remain even after the container encounters internal vacuum or the kink may disappear but leave a wrinkle in the plastic wall. Even a wrinkle makes the container unappealing and is considered to be commercially detrimental.
Typically, the specifications for such processes require the containers to withstand internal positive pressures of up to 3 psi. It is possible, however, for a pressure filling line to stop during the filling process, for example under unexpected or alarm conditions, and subject the container being filled to a filling pressure of greater than 3 psi.
SUMMARY OF THE INVENTIONProvided is a container capable of being hot filled with a product, sealed while the product is hot, and allowed to cool, thereby creating an internal vacuum. The container has improved positive pressure resistance during pressure filling and yet has sufficient vacuum absorption capabilities. The container has an enclosed base, a body having a sidewall that extends upwardly from the base, and an upper portion extending upwardly from the body to a finish on which a closure may be applied. The container also includes a pair of opposing vacuum panels disposed between front and rear portions of the sidewall of the body. The container has relatively smooth transitions between its vacuum panels and the front and rear portions of the sidewall and the container does not have vertical reinforcing ribs such that the radial dimension is small for each portion of the front and rear edges of the panel.
The vacuum panels have a generally flat field that transitions smoothly into the front and rear portions of the sidewall. Also, the vacuum panels each include a handgrip and a pair of inwardly extending windows formed at least partly in the field generally below the handgrip. The handgrip includes a gripping surface and at least a proximal wall and a distal wall. The gripping surface is adapted to receive a user's fingers on one of the vacuum panel handgrips and a user's thumb on the opposing one of the vacuum panel handgrips.
The proximal wall of the handgrip preferably merges smoothly with the rear portion of the sidewall The distal wall forms an oblique long wall angle A1 with a vertical line in elevational view and a short wall angle A2 with the field in transverse cross section. The long wall angle Al is preferably between approximately 10 degrees and approximately 25 degrees. The short wall angle A2 is preferably between approximately 85 degrees and approximately 115 degrees. Further, where structure having a substantially radial orientation is included, such as in the distal wall of the gripping surface, the radial component preferably has a relatively short vertical length in elevational view and is nearly radially oriented in transverse cross section. The container is designed to preferably achieve a failure mode in the form of a bulge in the handgrip distal wall when the container is subjected to a positive internal pressure. Preferably, the container can withstand and internal positive pressure of between 3.5 and 7.5 psi.
Also, provided is a method of hot-filling a bottle. According to the method, a bottle that is designed in accordance with the above description of the container is filled with contents at an elevated temperature and at a positive pressure of up to 9.0 psi. Then, the bottle is capped while the contents are still at an elevated temperature and the contents of the capped bottle are allowed to cool, which causes the vacuum panels to deflect inwardly in response to the cooling and shrinking of the contents.
BRIEF DESCRIPTION OF THE FIGURES
A bottle 10 includes an enclosed base 12, an upper portion 14, and a body 16 extending between base 12 and upper portion 14, as best shown in
Base 12 preferably is conventional and includes a reentrant portion 20 (shown only in dashed lines in
Body 16 includes a sidewall 38 and a pair of opposing vacuum panels 56. Sidewall 38 generally extends between shoulders 26 and 28 and preferably includes a front portion 42 and a rear portion 44. Front portion 42 and rear portion 44 preferably include horizontal stiffening ribs 46a and 46b, respectively. Preferably, neither front portion 42 nor rear portion 44 have horizontal stiffening ribs. Front portion 42 preferably a surface capable of receiving a label. The label surface of front panel 42 is generally straight in longitudinal cross section, but it is expected and acceptable for the longitudinal cross section of front portion 42 to deflect slightly in response to internal pressures within bottle 10. The desired magnitude of the deflection of front panel 42 is governed by label considerations, as will be understood by persons familiar with labeling technology for hot fill containers.
Stiffening ribs 46a and 48b are curved to match the curvatures of panels 42 and 44, respectively, and terminate at ends 48a and 48b, respectively. Preferably, sidewall 38 extends, rearward and arcuately, past ribs ends 48a of front portion 42; and sidewall 38 extends, frontward and arcuately, past rib ends 48b of rear portion 42; which portions of the sidewall are referred to a sidewall intermediate portions 50a and 50b, respectively. Preferably, sidewall intermediate portions 50a and 50b (i) do not have vertical stiffening ribs, or (ii) have ribs that have only a small vertical component (such as curved ribs or ribs forming an oblique angle with a vertical line), or (iii) have only horizontal ribs, or (iv) have stiffening structure that is part of a three dimensional window (described more fully below) and that has a small vertical dimension.
Each vacuum panel 40 includes a field 56 that is defined by the panel's front edge 58a and its opposing rear edge 58b.
Each panel 40 also includes a handgrip 60 and a pair of inwardly directed first window 90 and second window 96. Handgrip 60 includes a gripping surface 62 that preferably includes a pair of ribs 64. Handgrip 60 is defined by a proximal wall 66, a distal wall 68, an upper wall 70, and a lower wall 72. Walls 66, 68, 70, and 72 are joined by transitions 74a, 74b, 74c, and 74d as shown in
Gripping surface 60 preferably is flat except for a pair of ribs 64 that protrude outward from the remainder of the surface. Proximal wall 66 preferably is curved in transverse cross section, such as illustrated in
Distal wall 68 is on the opposite side of gripping surface 60 from proximal wall 66 and preferably is inclined at an angle from a vertical line by and angle A1, which will be referred to herein as the long wall angle. Preferably, angle A1 preferably is not 0° (that is, not vertical), preferably is between approximately 10 degrees and approximately 20 degrees, and more preferably, as illustrated in
As shown in
Also, the depth of gripping surface 64 (measured radially from the deepest point of surface 64 to the hypothetical extension of the panel field 46), which is shown schematically as dimension D in
All angle magnitudes provided herein are based on the bottle prior to filling. The wall angles may be chosen according to the overall container and panel size, wall thickness, blow molding parameters, and the like, as will be understood by persons familiar with blow molded bottle engineering.
Preferably, a first window 90 and a second window 96 are provided in the panel field 56. First window 90 has substantially straight edges 92 that merge panel field 56 with a window bottom surface 94. Preferably window bottom surface 94 is substantially flat. Second window 96 has substantially straight edges 98 that merge panel field 56 with a window bottom surface 100. The window edges 92 may be parallel to form a rectangle or square in elevational view, such as is illustrated by window 90. As illustrated by second window 96, the windows are not required to have a rectangular shape, as window 96 includes an extended portion 102 that extends upward to diminish the area of unreinforced field 56. As shown in the Figures, window 102 may extend outside of boundaries of panel 40.
Preferably, the vertical dimension of any radial structure in the panel 40 and vertical components of structure in the intermediate sidewalls 50a and 50b, such as the walls of window 102, have relatively small dimensions. The overall length L of distal main surface 76 is shown in
The dimensions herein are provided for the container shown having a sidewall diameter of approximately 4.5 inches and sidewall height (that it, between shoulders 26 and 28) of approximately 5.6 inches such that the container volume is 64 ounces. The dimensions and angles provided are not intended to limit the scope of the invention unless expressly set forth in the claims.
The present invention is illustrated by structure and function disclosed herein, and is not limited to the particular structure and function, but rather is limited according the claims. Further, advantages of the bottle 10 are provided in the context of pressure filling, and the present invention is not limited to any pressure filling process, but rather to any hot fill container having the claimed structure.
Claims
1. A bottle capable of being hot filled with a product, sealed while the product is hot, and allowed to cool, thereby creating an internal vacuum, said bottle comprising:
- an enclosed base including a reentrant portion and a heel;
- an upper portion extending upwardly to a finish on which a closure may be applied; and
- a body, located between the base and the upper portion, including a sidewall and a pair of opposing vacuum panels, the sidewall including a front portion and a rear portion, the vacuum panels being located generally between the front and rear portions, each one of the vacuum panels including: a generally flat field, a smooth transition between the field and each one of the front portion and the rear portion of the sidewall; a handgrip including a gripping surface and at least a proximal wall and a distal wall, the gripping surface is capable of receiving a user's fingers on one of the vacuum panel handgrips and a user's thumb on the opposing one of the vacuum panel handgrips, the distal wall forming an oblique long wall angle Al with a vertical line in elevational view and forming a short wall angle A2 of between approximately 85 degrees and approximately 115 degrees with the field in transverse cross section; a pair of inwardly extending windows formed at least partly in the field generally below the handgrip, wherein the failure mode of the container if subject to positive pressure is a bulge in the handgrip distal wall.
2. The bottle of claim 1 wherein the proximal wall smoothly merges with the rear portion of the sidewall.
3. The bottle of claim 1 wherein the short wall angle A2 is between approximately 85 degrees and approximately 105 degrees.
4. The bottle of claim 3 wherein the short wall angle A2 is approximately 90 degrees.
5. The bottle of claim 1 wherein the long wall angle Al is between approximately 10 degrees and approximately 25 degrees.
6. The bottle of claim 1 wherein the long wall angle A1 is approximately 15 degrees.
7. The bottle of claim 1 wherein the length of the distal wall is less than about 3.5 inches and greater than about 1.25 inches.
8. The bottle of claim 7 wherein the length of the distal wall is less that about 3.0 inches.
9. The bottle of claim 1 wherein the vertical component of the length of the distal wall is less than about 3.0 inches.
10. The bottle of claim 9 wherein the vertical component of the length of the distal wall is less than about 2.5 inches.
11. The bottle of claim 1 wherein the container withstands internal positive pressure of between 3.5 and 7.5 psi.
12. The bottle of claim 1 wherein the container withstands internal positive pressure of at least 6 psi.
13. The bottle of claim 1 wherein the distal wall is substantially straight in elevational view.
14. The bottle in claim 1 wherein the distal wall is substantially planar.
15. The bottle of claim 1 wherein the handgrip includes a lower wall and an upper wall.
16. The bottle of claim 15 wherein the upper wall is connected between an upper end of the distal wall and an upper end of the proximal wall.
17. The bottle of claim 16 wherein the upper wall is substantially straight and the handgrip includes a curved transition that connects the proximal wall and the distal wall together at upper ends thereof.
18. The bottle of claim 15 wherein the lower wall is curved and connects the proximal wall and the distal wall together at lower ends thereof.
19. The bottle of claim 1 wherein the front and rear portions of the sidewalls do not have vertical ribs.
20. The bottle of claim 1 wherein the front portion is a front label portion.
21. A method of hot-filling a bottle comprising the steps of:
- a) providing a bottle that includes described in claim 1;
- b) filling the bottle with contents at an elevated temperature at a positive pressure, wherein the bottle is capable of withstanding an internal pressure of up to 9.0 PSI; and
- c) capping the bottle while the contents are hot and enabling the capped bottle to cool, the vacuum panels deflecting inwardly in response to cooling and shrinking of the contents.
22. The method of claim 21 wherein the bottle in the hot filling step is capable of withstanding a positive internal pressure of up to 8.0 PSI.
23. The method of claim 21 wherein the bottle in the hot filling step is capable of withstanding a positive internal pressure of up to 7.0 PSI.
24. The method of claim 21 wherein the bottle in the hot filling step is capable of withstanding a positive internal pressure of approximately 6.6 PSI.
25. The method of claim 21 wherein the bottle in the hot filling step is capable of withstanding greater than greater than 3 psi.
26. The method of claim 21 wherein the bottle in the hot filling step is capable of withstanding greater than greater than 4 psi.
Type: Application
Filed: Feb 16, 2007
Publication Date: Aug 16, 2007
Applicant: Constar International Inc. (Philadelphia, PA)
Inventor: Satya Kamineni (Lockport, IL)
Application Number: 11/676,058
International Classification: B65D 90/02 (20060101);