WO1999008945A1

WO1999008945A1 - Distortion-resistant blow-molded plastic container

Info

Publication number: WO1999008945A1
Application number: PCT/US1998/017067
Authority: WO
Inventors: John W. Tobias; Roger M. Prevot
Original assignee: Graham Packaging Company, L.P.
Priority date: 1997-08-19
Filing date: 1998-08-18
Publication date: 1999-02-25

Abstract

A container (10) having a multi-faceted waist (22, 122, 222, 322, 422) construction. The waist (22, 122, 222, 322, 422) is formed by a plurality of chordal stiffening ribs (26, 126, 226, 326, 426) which define a regular transverse polygon (28, 128, 228, 328, 428). The shape of the waist (22, 122, 222, 322, 422) functions to resist ovalization of the container (10) at its waist (22, 122, 222, 322, 422) and dome (18) and to enhance the container (10) top loading capability. For maximum ovalization resistance, an odd number of chordal stiffening ribs (26, 126, 226, 326, 426) is utilized.

Description

DISTORTION-RESISTANT BLOW-MOLDED PLASTIC CONTAINER

Field of the Invention

The present invention relates to a blow-molded plastic container specifically designed to resist ovalization and to provide improved top loading capability, and more particularly, the present invention relates to a hot-fillable container having a multi-faceted waist.

Background of the Invention

Blow-molded plastic containers have become commonplace in packaging beverages, such as juice, and other liquid products. Such a container normally has a dome extending from a finish, an annular sidewall extending from a base, and an inwardly-extending, annular waist connecting the dome to the annular sidewall.

In the packaging of beverages, blow-molded plastic containers can be used in the so-called "hot-fill" process, i.e. filling the containers with a beverage at an elevated temperature, sealing the containers, and then allowing the beverage to cool. Various distortion-inducing forces act on the container as a result of hot-fill processing. As a result, hot-fillable plastic containers must provide sufficient flexure to compensate for these forces, while maintaining the structural integrity and aesthetic appearance of the filled container. Intended flexure is most commonly addressed with vacuum flex panels located in the annular sidewall of the container. An example of a container having flex panels is disclosed in U.S. Design Patent No. D.366,417 issued to Semersky and assigned to the assignee of the present application. A label is usually glued to the annular sidewall to cover the vacuum flex panels.

A problem experienced with hot-filled blow-molded plastic containers having a substantially annular cross-section is that the containers tend to distort from their intended shape. For instance, the forces resulting from hot-filling can cause the intended annular transverse cross-sectional shape of the waist and dome of the container to assume an oval transverse cross-sectional shape, creating carton packing and label adhesion problems, among others. Thus, to avoid the ovalization problem, the containers can be made of thicker plastic, can include complicated structural features, can be processed under very close tolerances, or can include all of the above.

In practice, the use of additional plastic does not provide a satisfactory solution to reinforce a container against distortion because of increased material costs. The use of complicated structures has not been satisfactory because of the need for complex molds and because such containers do not always perform, in production, in the manner intended by design. Processes requiring very close tolerances, such as filling the containers with beverage to a precise level, increases processing costs.

After containers are filled and sealed, they are subject to many external forces as they are packed, shipped and stored. For instance, filled containers are packed in bulk in cardboard boxes, or plastic wrap, or both. A bottom row of packed, filled containers may support several upper tiers of filled containers, and potentially, several upper boxes of filled containers. If the containers do not have sufficient top loading capability, they can experience compressive distortions and can be damaged. It has been found that some modifications incorporated in the structure of blow-molded plastic containers which were intended to resist ovalization, often result in compromising the ability of the containers to resist top loading. Thus, a container design must achieve a balance between compensating for forces created by hot-filling, maintaining intended annular cross-sectional shape, and providing sufficient top loading capability.

An example of a blow-molded plastic container which achieves the above stated balance is currently being manufactured by the assignee of the present application. The container has a plurality of chordal stiffening facets disposed in an endwise adjacent array extending transversely about the periphery of the dome of the container. The chordal stiffening facets define a transverse polygon-like structure in the dome of the container to prevent distortion of the container while increasing top load capability of the container.

Although various known hot-fillable blow-molded plastic containers, such as those having an annular waist as disclosed in the present assignee's U.S. design patent previously mentioned, may function satisfactorily for their intended purposes, there is a need for a blow-molded plastic container having an improved construction which both resists ovalization distortion due to hot-filling, and resists compressive distortions due to top loading. A container having the improved construction should also be capable of being made from a minimum of plastic to afford efficient manufacture.

Objects of the Invention

With the foregoing in mind, a primary object of the present invention is to provide a novel blow-molded plastic container which resists distortion.

Another object of the present invention is to provide an improved container capable of maintaining its structural integrity and aesthetic appearance despite the distortion-inducing internal container pressures caused by hot-filling.

A further object is to provide a container having an improved waist construction which provides sufficient top loading capabilities to withstand the rigors of shipping and storage while resisting ovalization due to hot-fill processing. A still further object is to provide a hot-fillable, plastic container with a unique waist configuration which resists ovalization and top load distortion yet which is inexpensive to manufacture, structurally sound, and aesthetically appealing.

Summary of the Invention

More specifically, the present invention provides a blow-molded plastic container which is ovalization and crush resistant. The container has a finish providing an opening, a base remote from the finish, and a body portion connecting the finish to the base. The improvement comprises a plurality of inwardly extending chordal stiffening ribs disposed in an endwise adjacent array extending transversely about the periphery of the body portion. The chordal stiffening ribs define a transverse polygon-like structure which prevents distortion of the body portion while it increases top loading capability of the container.

In a preferred embodiment, the body portion of the container includes a dome adjacent the finish and an annular sidewall adjacent the base, and the chordal stiffening ribs form a waist located between the dome and the annular sidewall. To maximize distortion prevention and top loading capability, an uneven number of chordal stiffening ribs are utilized to define a regular transverse polygon.

Brief Description of the Drawings The foregoing and other objects, features and advantages of the present invention should become apparent from the following description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an elevational view of a hot-fillable, blow-molded, plastic container having a multi-faceted waist embodying the present invention; FIG. 2 is a horizontal cross-sectional view of the multi -faceted waist taken along line 2-2 of FIG. 1;

FIG. 3 is a vertical cross-sectional view of the multi-faceted waist taken along line 3-3 of FIG. 2;

FIG. 4 is an elevational view of a second embodiment of a multi-faceted waist embodying the present invention;

FIG. 5 is a horizontal cross-sectional view of the multi-faceted waist taken along line 5-5 of FIG. 4;

FIG. 6 is an elevational view of a third embodiment of a multi-faceted waist embodying the present invention; FIG. 7 is a horizontal cross-sectional view of the multi-faceted waist taken along line 7—7 of FIG. 6;

FIG. 8 is an elevational view of a fourth embodiment of a multi-faceted waist embodying the present invention;

FIG. 9 is a horizontal cross-sectional view of the multi-faceted waist taken along line 9-9 of FIG. 8 ;

FIG. 10 is an elevational view of a fifth embodiment of a multi-faceted waist embodying the present invention; and

FIG. 11 is a horizontal cross-sectional view of the multi-faceted waist taken along line 11-11 of FIG. 10. Detailed Description of the Preferred Embodiments

FIG. 1 illustrates a typical blow-molded, generally cylindrical plastic container 10 which is particularly suited for the waist construction of the present invention. The illustrated container 10 is particularly suited for packaging beverages, such as juice, however, the waist construction of the present invention can be utilized in other container configurations which may be used to package any of a variety of products.

The container 10, as illustrated, has a finish 12 connected to a base 14 by a body portion 16. The body portion 16 includes a dome 18 adjacent the finish 12 and an annular sidewall 20 adjacent the base 14. An inwardly-extending waist 22 connects the annular bottom of the dome 18 to the top of the annular sidewall 20. The container 10, as shown, is particularly suited for hot-filling, since it has a series of identical, spaced-apart, vertically elongate collapse, or vacuum flex, panels 24 around the periphery of the annular sidewall 16.

The container 10 experiences high levels of stress when processed at product fill temperatures of about 180 to 195° F , and ,if it had a conventional annular waist (not shown), the stress may cause the annular waist and dome to ovalize. However, the container 10 illustrated in FIG. 1 has the improved multi-faceted waist construction of the present invention which provides an aesthetically pleasing package while resisting distortion of the waist and dome caused by hot-filling and increasing container top loading capability.

As illustrated, the multi-faceted waist 22 extends inwardly and horizontally along the periphery of the body portion 16 between the dome 18 and the annular sidewall 20. However, the multi-faceted rib-like construction of the present invention can be utilized anywhere on the body portion 16 where additional resistance to distortion is desired, such as, for example, in a label mounting area above and/or below the vacuum flex panels. The multi-faceted rib-like construction is particularly useful as a waist because the body portion of the container nearest the base of the container is normally prevented from distortion because of the stiffness of the base; whereas, the upper body portion of the container further from the base generally requires additional resistance to distortion. As best shown in FIG. 2, the waist 22 consists of a plurality of chordal stiffening ribs 26 disposed in an endwise adjacent array extending transversely about the periphery of the body portion 16 such that the chordal stiffening ribs 26 define a polygon 28 in transverse cross-section. Each of the chordal stiffening ribs 26 has opposite ends 30 which cooperate with an end 30 of an adjacent rib 26 to form vertical posts 32' at the apexes 32 of the polygon 28. Preferably, all the chordal stiffening ribs 26 are identical in shape and size so that a regular transverse polygon 28 is defined.

The embodiment of the waist 22 illustrated in FIGs. 1-3 utilizes seven chordal stiffening ribs 26 which define a regular transverse heptagon 28. As best illustrated in FIG. 3, each of the ribs 26 extends in a substantially straight line between its opposite ends 30, and the apexes 32 of the heptagon 28 extend entirely within an outside perimeter "P" defined by the outer periphery of the annular sidewall 20. As best illustrated in FIG. 3, each rib 26 has an inwardly-convex elevational cross-section throughout its length. The center portion 34 of each rib 26 extends to a greater inward extent relative to the perimeter "P" than the rest of the rib 26. Thus, the center portion 34 of each rib 26 has an inwardly-convex cross-section with a smaller radius of curvature "Rl " than the radius of curvature "R2" of the cross-section at the ends 30 of the ribs 26. A second embodiment of a waist 122 according to the present invention is illustrated in FIGs. 4-5. Similar to the above described embodiment, it has seven chordal stiffening ribs 126 which extend in a straight line between their opposite ends 130 and which form a transverse heptagon 128 which is entirely within a perimeter "Pa" defined by the annular sidewall 120. However, each rib 126 has an innermost facet wall portion 136 which is substantially planar and substantially vertical in orientation. As best illustrated in FIG. 4, the center portion 134 of each rib 126 is the only portion of the rib 126 which is inwardly-convex in elevational cross-section. Thus, each facet wall portion 136 has an hourglass shape in elevation.

A third embodiment of a waist 222 according to the present invention is illustrated in FIGs. 6-7. The waist 222 has five chordal stiffening ribs 226 which are slightly outwardly-bowed, or arcuate, between their opposite ends 230 instead of being substantially straight as the preceding embodiments. Thus, non-angular, or slightly rounded, apex posts 232 are formed at the intersection of adjacent ribs 226. The five arcuate ribs 226 define a transverse pentagon-like structure 228 which is entirely within a perimeter "Pb" defined by the annular sidewall 220. Each arcuate rib 226 has an innermost facet wall portion 236 which forms a substantially smooth, vertically-oriented surface. As best illustrated in FIG. 6, the center portion 234 of each rib 226 is the only portion of the rib 226 which is inwardly-convex in elevational cross-section. Thus, each facet wall portion 236 has an arcuate hourglass shape in elevation.

A fourth embodiment of a waist 322 according to the present invention is illustrated in FIGs. 8-9. The waist 322 has five chordal stiffening ribs 326 which extend in a straight line between their opposite ends 330. The ends 330 of the five ribs 326 extend to the perimeter "Pc" defined by the annular sidewall 320 and do not intersect an adjacent rib 326. Rather, a relatively small land 338 extends between ends 330 of adjacent ribs 326 so that a transverse pentagon-like structure 328 is defined having truncated apexes 332. The lands 338 extend directly from the dome 318 to the annular sidewall 320 between each pair of adjacent chordal stiffening ribs 326 and provide post-like reinforcement for top loads. Each rib 326 has an innermost facet wall portion 336 which is substantially planar, vertically-oriented, and hourglass shaped. As best illustrated in FIG. 8, the center portion 334 of each rib 326 is the only portion of the rib 326 which is inwardly-convex in elevational cross-section.

A fifth embodiment of a waist 422 according to the present invention is illustrated in FIGs. 10-11. The waist 422 has five chordal stiffening ribs 426 which are outwardly-bowed, or arcuate, between their opposite ends 430. Thus, non- angular, rounded, apexes 432 are formed at the interconnection of adjacent ribs 426. The five arcuate ribs 426 define a transverse pentagon-like structure 428 which is entirely within a perimeter "Pd" defined by the annular sidewall 420. As best illustrated in FIG. 10, each rib 426 has an inwardly-convex elevational cross-section throughout its length. The center portion 434 of each rib 426 extends to a greater inward extent relative to the perimeter "Pd" than the rest of the rib 426. Thus, the center portion 434 of each rib 426 has an inwardly-convex cross-section with a smaller radius of curvature "Rid" than the radius of curvature "R2d" of the cross- section at the ends 430 of the ribs 426. While the five above-described embodiments provide examples of multi- faceted waist constructions according to the present invention, various modifications may be made. For instance, the preferred number of chordal stiffening ribs (26, 126, 226, 326, 426) for each waist (22, 122, 222, 322, 422) is in a range of about three to about eleven; however, any number of chordal stiffening ribs can be utilized. To maximize ovalization resistance, a regular polygon structure (28, 128, 228, 328, 428) is preferably formed with an odd number of chordal stiffening ribs which is believed to strongly resist ovalization because it ensures the absence of a pair of apexes which are diametrically-opposite one another. Alternatively, if maximum ovalization resistance is not required, an even number of chordal stiffening ribs could be utilized such as, for example, four, six, eight or ten.

As illustrated in the various embodiments, the shape of the chordal stiffening ribs (26, 126, 226, 326, 426) can vary. For instance, as illustrated in FIGs. 2, 5, and 9, the ribs can extend in a straight line between opposite ends; or, as illustrated in FIGs. 7 and 11, they can be bowed slightly. Thus, the transverse polygon-like structures (28, 128, 228, 328, 428) can be formed with straight or arcuate sides. The polygon-like structure can extend entirely within the perimeter (P, Pa, Pb, Pc, Pd) defined by the outer periphery of the annular wall (20, 120, 220, 320, 420) as illustrated in FIGs. 2, 5, 7 and 11; or its apexes can extend to the perimeter, as illustrated in FIG. 9. The apexes can form sharp angles as illustrated in FIGs. 2 and 5; can be rounded as illustrated in FIGs. 7 and 11 ; or can be truncated as illustrated in FIG. 9.

The elevational cross-section of the chordal stiffening ribs (26, 126, 226, 326, 426) can also vary. The elevational cross-section can be of an inwardly-convex shape throughout the length of each chordal stiffening rib as illustrated in FIGs. 1, 3 and 10; or they can include an innermost facet wall portion (136, 236, 336) which interrupts the convex shape as illustrated in FIGs. 4, 6 and 8.

The described container has an improved waist construction that affords enhanced top loading capability and resists ovalization. The container can be efficiently and inexpensively blow-molded from any of several commercially-available plastics, such as PET, and provides an aesthetic appearance despite the rigors of hot- fill processing and top loading during shipping.

While preferred containers have been described in detail, various modifications, alterations, and changes may be made without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. In a blow-molded plastic container (10) having a finish (12) providing an opening, a base (14) remote from the finish (12), and a body portion (16) connecting the finish (12) to the base (14), the improvement comprising a plurality of inwardly extending chordal stiffening ribs (26, 126, 226, 326, 426) disposed in an endwise adjacent array extending transversely about the periphery of the body portion (16), said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) defining a transverse polygon-like structure (28, 128, 228, 328, 428), whereby said ribs (26, 126, 226, 326, 426) prevent distortion of the body portion (16) and increase top loading capability of the container (10).

2. A blow-molded plastic container (10) according to claim 1, wherein the body portion (16) includes a dome (18) adjacent the finish (12) and an annular sidewall (20, 120, 220, 320, 420) adjacent the base (14), and wherein said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) form a waist (22, 122, 222, 322, 422) between the dome (18) and the annular sidewall (20, 120, 220, 320, 420).

3. A blow-molded plastic container (10) according to claim 2, wherein said waist (22, 122, 222, 322, 422) consists of an uneven number of said chordal stiffening ribs (26, 126, 226, 326, 426).

4. A blow-molded plastic container (10) according to claim 3, wherein each of said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) is identical in size and in shape.

5. A blow-molded plastic container ( 10) according to claim 4, wherein each of said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) has opposite ends (30, 130, 230, 330, 430) and extends substantially in a straight line between said opposite ends (30, 130, 230, 330, 430).

6. A blow-molded plastic container (10) according to claim 4, wherein each of said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) has opposite ends (30, 130, 230, 330, 430) and is bowed between said opposite ends (30, 130, 230, 330, 430).

7. A blow-molded plastic container (10) according to claim 6, wherein each of said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) is outwardly bowed between said opposite ends (30, 130, 230, 330, 430).

8. A blow-molded plastic container (10) according to claim 6, wherein each of said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) is arcuate between said opposite ends (30, 130, 230, 330, 430).

9. A blow-molded plastic container (10) according to claim 4, wherein said uneven number of chordal stiffening ribs (26, 126, 226, 326, 426) is in a range of from about three to about eleven.

10. A blow-molded plastic container (10) according to claim 9, wherein said transverse polygon-like structure (28, 128, 228, 328, 428) formed by said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) is a pentagon (28).

11. A blow-molded plastic container (10) according to claim 9, wherein said transverse polygon-like structure (28, 128, 228, 328, 428) formed by said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) is a heptagon (128).

12. A blow-molded plastic container (10) according to claim 4, wherein the annular sidewall (20, 120, 220, 320, 420) has an outer periphery, and wherein each of said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) extends entirely within said outer periphery of said annular sidewall (20, 120, 220, 320, 420).

13. A blow-molded plastic container (10) according to claim 4, wherein the annular sidewall (20, 120, 220, 320, 420) has an outer periphery and said transverse polygon-like structure (28, 128, 228, 328, 428) has a plurality of apexes (32, 132, 232, 332, 432), and wherein each of said apexes (32, 132, 232, 332, 432) extends to an outward extent substantially equal to said annular sidewall diameter (20, 120, 220, 320, 420).

14. A blow-molded plastic container (10) according to claim 4, wherein each of said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) has an elevational cross-section which is inwardly convex.

15. A blow-molded plastic container (10) according to claim 4, wherein each of said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) form vertically-disposed posts at opposite ends thereof.

16. A blow-molded plastic container (10) according to claim 15, wherein the plurality of chordal stiffening ribs (26, 126, 226, 326, 426) define a polygon (28, 128, 228, 328, 428) in transverse cross section and said posts are located at the apexes (32, 132, 232, 332, 432) of said polygon (28, 128, 228, 328, 428).

17. An ovalization and crush resistant container (10) having a finish (12), a base (14) remote from the finish (12), a dome (18) adjacent the finish (12), an annular sidewall (20, 120, 220, 320, 420) adjacent the base (14), and an inwardly extending waist (22, 122, 222, 322, 422) located between the dome (18) and the annular sidewall (20, 120, 220, 320, 420), the improvement wherein the waist (22, 122, 222, 322, 422) includes a plurality of chordal stiffening ribs (26, 126, 226, 326, 426) disposed in an endwise adjacent array extending transversely about the periphery of the container (10), said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) being of an uneven number and defining a regular transverse polygon (28, 128, 228, 328, 428).

18. In a blow-molded plastic container ( 10) having a finish (12) providing an opening, a base (14) remote from the finish (12), and a body portion (16) connecting the finish (12) to the base (14), the body portion (16) having a dome (18) adjacent the finish (12) and an annular sidewall (20, 120, 220, 320, 420), the improvement comprising a waist (22, 122, 222, 322, 422) having a plurality of inwardly extending chordal stiffening ribs (26, 126, 226, 326, 426) disposed in an endwise adjacent array extending transversely about the periphery of the body portion (16) between the dome (18) and the annular sidewall (20, 120, 220, 320, 420), said plurality of chordal stiffening ribs (26, 126, 226, 326, 426) being of an uneven number, whereby said waist (22, 122, 222, 322, 422) prevents distortion of the body portion (16) and increases top loading capability of the container (10).

19. A blow-molded plastic container (10) according to claim 18, wherein the annular sidewall (20, 120, 220, 320, 420) has an outer periphery and said transverse polygon-like structure (28, 128, 228, 328, 428) has a plurality of apexes (32, 132, 232, 332, 432) which form post-like structures extending directly between the dome (18) and the annular sidewall (20, 120, 220, 320, 420) at each end of each stiffening rib (26, 126, 226, 326, 426).

20. A blow-molded plastic container (10) according to claim 18, wherein said uneven number of stiffening ribs (26, 126, 226, 326, 426) is in a range of three to eleven.