The present disclosure relates to a footed container base.
This section provides background information related to the present disclosure, which is not necessarily prior art.
As a result of environmental and other concerns, plastic containers, more specifically polyester and even more specifically polyethylene terephthalate (PET) containers, are being used more than ever to package numerous commodities previously supplied in glass containers. Manufacturers and fillers, as well as consumers, have recognized that PET containers are lightweight, inexpensive, recyclable and manufacturable in large quantities.
Blow-molded plastic containers have become commonplace in packaging numerous commodities. PET is a crystallizable polymer, meaning that it is available in an amorphous form or a semi-crystalline form. The ability of a PET container to maintain its material integrity relates to the percentage of the PET container in crystalline form, also known as the “crystallinity” of the PET container. The following equation defines the percentage of crystallinity as a volume fraction:
where ρ is the density of the PET material; ρa is the density of pure amorphous PET material (1.333 g/cc); and ρc is the density of pure crystalline material (1.455 g/cc).
Container manufacturers use mechanical processing and thermal processing to increase the PET polymer crystallinity of a container. Mechanical processing involves orienting the amorphous material to achieve strain hardening. This processing commonly involves stretching an injection molded PET preform along a longitudinal axis and expanding the PET preform along a transverse or radial axis to form a PET container. The combination promotes what manufacturers define as biaxial orientation of the molecular structure in the container. Manufacturers of PET containers currently use mechanical processing to produce PET containers having approximately 20% crystallinity in the container's sidewall.
Typically, an upper portion of the plastic container defines an opening. This upper portion is commonly referred to as a finish and includes some means for engaging a cap or closure to close off the opening. In the traditional injection-stretch blow molding process, the finish remains substantially in its injection molded state while the container body is formed below the finish. The finish may include at least one thread extending radially outwardly around an annular sidewall defining a thread profile. In one application, a closure member or cap may define a complementary thread, or threads, that are adapted to cooperatively mate with the threads of the finish.
In some applications, plastic containers must withstand extreme pressures, such as when containing carbonated beverages. One common design includes providing plastic containers having multiple feet-like structures formed around the base. A typical base consists of five such feet and is commonly referred to as a petaloid base. An exemplary container including a petaloid base is described in U.S. Pat. No. 7,891,513 (“'513 patent”) titled “Container Base with Feet,” which issued on Feb. 22, 2011 and is assigned to Amcor Limited. The disclosure of U.S. Pat. No. 7,891,513 is incorporated herein by reference. Additional exemplary containers are described in the following patents, the disclosures of which are also incorporated herein by reference: U.S. Pat. No. 5,484,072 titled “Self-Standing Polyester Containers for Carbonated Beverages,” which issued on Jan. 16, 1996 and is assigned to Amcor Limited; and U.S. Pat. No. 5,529,196 titled “Carbonated Beverage Container With Footed Base Structure,” which issued on Jun. 25, 1996 and is assigned to Amcor Limited.
In some instances, conventional petaloid base designs do not have the desired performance characteristics to withstand the extreme pressures of carbonated beverages, particularly when manufactured at high speeds (i.e., greater than 1,600 containers per hour for each mold cavity). For example, some petaloid base designs experience creasing at the feet thereof caused by carbonation pressure within the container after it has been filled. Under normal conditions, a filled and capped container can experience an internal carbonation pressure in excess of 75 PSI (5 bar). Creasing can become more pronounced as customers require lighter weight containers. Prior art
There is thus a need for a plastic container design that has a base capable of withstanding extreme internal pressure, and exhibits significant increased resistance to breakage and creasing at the feet subsequent to filling. Furthermore, there is a need to provide a container base providing increased stability to the container when empty as well as subsequent to filling. As described herein, the teachings of this present application address these needs by, for example, providing a container base with a smooth, balanced, and stable base geometry that is able to distribute internal pressure to reduce stress in the feet of the container base.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
The present teachings provide for a plastic container including an upper portion, a cylindrical sidewall, and a base portion. The upper portion defines an opening at an upper end of the container. The cylindrical sidewall extends from the upper portion and defines a storage volume accessible through the opening. The base portion extends from the cylindrical sidewall to a base end of the container that is opposite to the upper end of the container. The base portion includes a gate area at an axial center of the base portion, a plurality of feet radially spaced apart about the axial center, a plurality of straps, and a plurality of fillet areas. Each one of the plurality of straps are arranged between neighboring ones of the plurality of feet, and the plurality of fillet areas. Each one of the plurality of fillet areas are arranged between one of the plurality of feet and straps on opposite sides thereof. The base portion further includes a cumulative strap surface area and a cumulative foot surface area. The cumulative strap surface area is defined by a total surface area of the plurality of straps, the gate area, and half a total surface area of the plurality of fillet areas. The cumulative foot surface area is defined by a total surface area of the plurality of feet and half the total surface area of the plurality of fillet areas. The base portion has a ratio of cumulative foot surface area to cumulative strap surface area in the range of 2.4-2.8:1.
The present teachings further provide for a one-piece plastic container including an upper portion, a cylindrical sidewall, and a base portion. The upper portion defines an opening at an upper end of the container. The cylindrical sidewall extends from the upper portion and defines a storage volume accessible through the opening. The base portion extends from the cylindrical sidewall to a base end of the container that is opposite to the upper end of the container. The base portion includes a plurality of feet radially spaced apart about an axial center of the base portion. Each one of the plurality of feet includes an outer foot surface at an outer diameter of the base portion that tapers inward at a first angle along a length thereof extending towards the base end of the container. A plurality of straps are arranged between neighboring ones of the plurality of feet. Each one of the plurality of straps taper inward along a length thereof extending towards the axial center of the base portion. A plurality of fillet areas each include a first fillet portion extending along a first side of each one of the plurality of straps, and a second fillet portion extending along a second side of each one of the plurality of straps. The first and the second fillet portions are arranged to taper towards one another at a second angle along respective lengths thereof extending towards the axial center of the base portion. The first angle is generally similar to the second angle.
The present teachings also provide for a one-piece plastic container. The container includes an upper portion defining an opening at an upper end of the container. A cylindrical sidewall extends from the upper portion and defining a storage volume accessible through the opening. A base portion extends from the cylindrical sidewall to a base end of the container that is opposite to the upper end of the container. A plurality of feet are included with the base portion. The plurality of feet are radially spaced apart about the axial center of the base portion and each includes a circular contact pad configured to support the container upright on a support surface. Each contact pad has a pad length extending radially away from a longitudinal axis of the container and a pad width extending generally perpendicular to the pad length. A plurality of straps are arranged between neighboring ones of the plurality of feet.
The present teachings still further provide for a one-piece plastic container including an upper portion defining an opening at an upper end of the container. A cylindrical sidewall extends from the upper portion and defines a storage volume accessible through the opening. A base portion extends from the cylindrical sidewall to a base end of the container that is opposite to the upper end of the container. A plurality of feet are included with the base portion. The feet are radially spaced apart about the axial center of the base portion. Each one of the plurality of feet has a foot length extending radially away from a longitudinal axis of the container. A foot width extends generally perpendicular to the foot length. A foot radius extends along at least a portion of the foot width. The foot width is about twice as large as the root radius. A plurality of straps are arranged between neighboring ones of the plurality of feet.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
With initial reference to
The container 10 is an injection-stretch blow molded, biaxially oriented container having a unitary construction from a single or multi-layer material. A well-known stretch-molding process for making the container 10 is generally set forth in the '513 patent (the disclosure of which is incorporated herein by reference as set forth above), and includes manufacture of a preform or a polyester material, such as polyethylene terephthalate (PET), having a shape similar to a test-tube with a generally cylindrical cross-section and a length typically about 50% that of a resultant height H of the container 10. As illustrated in
The container 10 generally includes an upper portion 12 and a base portion 14. Extending between the upper portion 12 and the base portion 14 is a cylindrical sidewall 16, which defines a storage volume 18. Extending from an upper portion of the sidewall 16 is a shoulder region 20 of the upper portion 12. The shoulder region 20 extends towards a finish 22 of the upper portion 12, and gradually curves or tapers inward as it extends towards the finish 22. A neck 24 of the upper portion 12 connects the finish 22 to the shoulder region 20.
The finish 22 includes an annular sidewall 26. Extending from an outer edge of the annular sidewall 26 proximate to the neck 24 is an annular rib 28. Threads 30 also extend from an outer surface of the annular sidewall 26, on a side of the annular rib 28 opposite to the neck 24. The threads 30 can be configured in any suitable manner to permit cooperation with threads of a suitable closure or cap, in order to couple the closure or cap to the finish 22 and cover or close an opening 32 defined by the annular sidewall 26. The opening 32 provides access to the storage volume 18, and is at an upper end 34 of the container 10.
The upper end 34 is at an end of the container 10 opposite to a base end 36 of the base portion 14. Longitudinal axis A of the container 10 extends through a radial center of the opening 32 and along a length of the container 10 generally at a center of the container 10. The height H of the container 10 generally extends from the base end 36 to an interface between the shoulder region 20 and the finish 22.
With continued reference to
Each foot 60 generally includes an outer foot surface 62. Each of the outer foot surfaces 62 generally extend from about an outer surface 80 of the base portion 14 at an outer diameter thereof towards the base end 36. With reference to
Each foot 60 includes a first side surface 70 adjacent to the first edge 64 and a second side surface 72 adjacent to the second edge 66. The first and second side surfaces 70 and 72 are generally angled and sloped such that they converge generally between the distal end 68 of the outer foot surface 62 and a bottom surface 74 of the feet 60. The bottom surface 74 generally mates with the first and second side surfaces 70 and 72 at the base end 36. From the first and second side surfaces 70 and 72, the bottom surfaces 74 extend towards the gate area 50 and generally taper away from the base end 36.
The base portion 14 further includes a plurality of contact pads 76 at the base end 36. The contact pads 76 are generally configured to support the container 10 upright on a support surface 38, such as a table or any planar surface. Each one of the feet 60 includes one of the contact pads 76 as illustrated, however, each foot 60 can be provided with any suitable number of contact pads 76. Each one of the contact pads 76 is generally located at the interface between the first and second side surfaces 70 and 72 and the bottom surface 74 of the feet 60. The contact pads 76 can be arranged in an overall circular pattern along contact diameter Dc, which extends about the base end 36. Each one of the contact pads 76 is generally round or circular as illustrated, and thus not rectangular. However, the contact pads 76 can have any suitable shape configured to adequately support the container 10 upright on the support surface 38.
With reference to
The contact pads 76 can have any suitable surface area. For example, a total surface area of all of the plurality of contact pads 76 can be 1% about 1%, or within the range of 0.5%-1.5% of a total surface area of the base portion 14. A total surface area of the contact pads 76 can be 1.4%, about 1.4%, or within the range of 0.9%-1.9% of a cumulative foot surface area of the feet 60, which as defined herein can be a total surface area of all of the feet 60 and half of a total surface area of all fillet areas 90. When the base portion 14 includes five contact pads 76, the total surface area of the five contact pads 76 can be 1.958 cm2, about 1.958 cm2, or within about 0.5 cm2 of 1.958 cm2.
Each foot 60 generally includes, with reference to
With additional reference to
The base portion 14 further includes a plurality of fillet areas 90. Each one of the fillet areas 90 extends about a different one of the feet 60. For example, each fillet area 90 includes a first fillet portion 92 and a second fillet portion 94. The first and second fillet portions 92 and 94 extend along opposite sides of the feet 60 and converge proximate to the gate area 50. The fillet areas 90 are generally concave recesses defined within the base portion 14.
With reference to
The base portion 14 further includes a plurality of straps 102. Each one of the straps 102 is located between neighboring feet 60, and particularly between neighboring fillet areas 90. Each strap 102 generally includes an outermost portion 104, an intermediate portion 106, and a hemispherical portion 108. The outermost portion 104 is proximate to, or adjacent to, the outer surface 80, which is generally at the outermost diameter of the base portion 14. The intermediate portion 106 is between the hemispherical portion 108 and the outermost portion 104.
The hemispherical portion 108 continuously extends from the intermediate portion 106 to the gate area 50. The hemispherical portion 108 is generally smooth and tapers inward along a length thereof from the intermediate portion 106 to the gate area 50. The hemispherical portion 108 is most narrow proximate to, but spaced apart from, the gate area 50. The hemispherical portion 108 advantageously increases the overall strength of the base portion 14 so as to enhance the ability of the base portion 14 to resist internal pressures exerted upon the base portion 14, which may result in creasing at the feet 60.
The hemispherical portions 108 can have any suitable surface area. For example, the hemispherical portions 108 can have a total surface area that is 9%, about 9%, within about 2% of 9%, 8.7%, about 8.7%, or within about 2% of 8.7% of a total surface area of the base portion 14. A ratio of a total surface area of the base portion 14 with respect to a total surface area of the hemispherical portions 108 can thus be 11.5:1, or about 11.5:1. For example, if the base portion 14 has a total surface area of 194.646 cm2, the total surface area of all of the hemispherical portions 108 and the gate area 50 can be 16.998 cm2, about 16.998 cm2 or within 5.0 cm2 of 16.998 cm2. With reference to
The feet 60, the fillet areas 90, and the straps 102 can each have any suitable area and dimensions in order to enhance the overall strength of the base portion 14, and decrease the possibility of creasing at the feet 60. For example, a cumulative foot surface area (including a total surface area of all of the feet 60 and half of a total surface area of all of the fillet areas 90) and a cumulative strap surface area (including a total surface area of all of the straps 102, a surface area of the gate area 50, and half of the total surface area of all of the fillet areas 90) can be provided at a ratio of 2.4-2.8:1, 2.6:1, or about 2.6:1. Of a total surface area of the base portion 14, 67%-77%, 72%, about 72%, or within 5% of 72% thereof can be the cumulative foot surface area, and 23%-33%, 28%, about 28%, or within 5% of 28% thereof can be the cumulative strap surface area. Thus a ratio of the total surface area of the base portion 14 with respect to the cumulative strap surface area can be 3.4-3.8:1, 3.6:1, or about 3.6:1. A ratio of the total surface area of the base portion 14 with respect to the cumulative foot surface area can be 1.2-1.6:1, 1.4:1, or about 1.4:1. For example, where the total surface area of the base portion 14 is 194.646 cm2 or about 194.646 cm2, the cumulative strap surface area can be 54.743 cm2, about 54.743 cm2 or within 10 cm2 of 54.743 cm2, and the cumulative foot surface area can be 139.904 cm2, about 139.904 cm2 or within 10 cm2 139.904 cm2.
The fillet areas 90 can have a total fillet surface area of 48.813 cm2, about 48.813 cm2, or within 5 cm2 of 48.813 cm2. The gate area 50 can have a total surface area of 1.725 cm2, about 1.725 cm2, or within 0.5 cm2 of 1.725 cm2. The straps 102 (independent of the fillet areas 90) can have a total combined surface area of 28.611 cm2, about 28.611 cm2, or within 5 cm2 of 28.611 cm2. The feet 60 (independent of the fillet areas 90) can have a total combined surface area of 115.497 cm2, about 115.497 cm2, or within 10 cm2 of 115.497 cm2.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
Filing Document | Filing Date | Country | Kind |
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PCT/US2013/072783 | 12/3/2013 | WO | 00 |