Plastic container with anti-bulge panel

A plastic container includes a finish portion defining an opening and a main body portion having a shape that is substantially polygonal in transverse cross-section. The main body portion has a maximum lateral dimension. At least one of the side panels includes a substantially flat portion for receiving a label and a concave portion having an average radius. A ratio of the average radius to the maximum lateral dimension is substantially within a range of about 1.0 to about 2.0. The side panel having the concave portion further has an inwardmost portion and an outwardmost portion, with a first maximum lateral distance being defined between the inwardmost portion and the outwardmost portion. A second maximum lateral distance is defined between the inwardmost portion and one of the substantially flat portions. A ratio of the first distance to the second distance is substantially within a range of about 0.8 to about 1.2.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the field of packaging, and more specifically to the field of blow molded plastic containers for packaging substances such as beverages.

2. Description of the Related Technology

Many products that were previously packaged using glass containers are now being supplied in plastic containers. Polyethylene terephthalate (PET) thermoplastic resins are polyester materials that provide clarity and transparency that is comparable to glass. PET possesses the processing characteristics, chemical and solvent resistance and high strength and impact resistance that are required for packaging products such as juices, soft drinks and water. PET containers are lightweight, inexpensive, and recyclable and can be economically manufactured in large quantities. They will not shatter and create potentially dangerous shards when dropped, as glass containers may.

PET containers have conventionally been manufactured using the stretch blow molding process. This involves the use of a pre-molded PET preform having a threaded portion and a closed distal end. The preform is first heated and then is longitudinally stretched and subsequently inflated within a mold cavity so that it assumes the desired final shape of the container. As the preform is inflated, it elongates and stretches, taking on the shape of the mold cavity. The polymer solidifies upon contacting the cooler surface of the mold, and the finished hollow container is subsequently ejected from the mold.

In order to minimize materials costs, a plastic container should ideally be constructed to use as little plastic resin as possible. Such lightweighting is usually accomplished by making the sidewall of the container as thin as possible, but this adversely impacts the strength and rigidity of the sidewall. In larger plastic beverage containers, such as those having a volumetric capacity of 64 ounces or greater, outward bulging of the sidewall as result of the hydrostatic pressure exerted by the liquid within the container can be problematic, particularly in containers that are noncircular in transverse cross-section.

A need has existed for an improved noncircular plastic container that possesses improved resistance to outward bulging of the sidewall with respect to conventional containers, without having a significant negative impact on material costs.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide an improved noncircular plastic container that possesses improved resistance to outward bulging of the sidewall with respect to conventional containers, without having a significant negative impact on material costs.

In order to achieve the above and other objects of the invention, a plastic container according to a first aspect of the invention includes a finish portion defining an opening and a main body portion having a shape that is substantially polygonal in transverse cross-section with a plurality of side panels. The main body portion has a maximum lateral dimension. At least one of the side panels includes a substantially flat portion for receiving a label and a concave portion having an average radius. A ratio of the average radius to the maximum lateral dimension is substantially within a range of about 1.0 to about 2.0.

A plastic container according to a second aspect of the invention includes a finish portion defining an opening, and a main body portion having a shape that is substantially polygonal in transverse cross-section with a plurality of side panels. The main body portion has a maximum lateral dimension. At least one of the side panels includes a first upper substantially flat portion for receiving a label, a second, lower substantially flat portion for receiving a label and a central concave portion positioned between the first and second substantially flat portions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular toFIG. 1, a plastic container10that is constructed according to a preferred embodiment of the invention is preferably fabricated from a plastic material such as polyethylene terephthalate (PET) using a conventional stretch blow molding process. Plastic container10preferably has an internal volume that is at least 64 ounces, and that is more preferably at least 80 ounces.

Referring toFIG. 1, plastic container10preferably includes a threaded finish portion11, a main body portion12and a bottom portion14that is unitary with the main body portion12. The main body portion12includes an upper dome portion16and a label portion18which is substantially polygonal when viewed in transverse cross-section. AsFIGS. 3-5show, the label portion18of the main body portion12in the preferred embodiment is substantially rectangular in transverse cross-section.

Label portion18includes a plurality of side panels20,22,24,26, including front and rear side panels20,22. At least one of the side panels20,22,24,26includes at least one substantially flat portion28,30for receiving a label and a concave portion32having an average radius RC. The main body portion12has a maximum lateral dimension DMAX, which is best shown inFIG. 2. A ratio RC/DMAXof the average radius RCto the maximum lateral dimension DMAXis preferably substantially within a range of about 1.0 to about 2.0, more preferably substantially within a range of about 1.1 to about 1.9 and most preferably substantially within a range of about 1.2 to about 1.8.

In the preferred embodiment, the average radius RCis substantially unchanged when viewed in transverse cross-section from an upper portion of the concave portion32to a lower portion of the concave portion32.

In the preferred embodiment, the front and rear side panels20,22each have a first, upper substantially flat portion28near an upper end of the respective panel20,22for receiving a first portion of a label and a second, lower substantially flat portion30near a lower end of the respective panel20,22for receiving another portion of the label. A central, concave portion32is positioned between the upper and lower substantially flat portions28,30.

A plurality of reinforcing ribs34,36,38,40,42are preferably defined in each of the front and rear side panels20,22. The reinforcing ribs34,36,38,40,42in the preferred embodiment have a substantially horizontal orientation.

Each of the side panels20,22that have the concave portion32has an inwardmost portion44and an outwardmost portion46, asFIG. 4best shows. The outwardmost portion46preferably extends laterally outwardly from a central longitudinal axis50to substantially the same extent as the substantially flat portion28. AsFIG. 4shows, a first maximum lateral distance D1is defined between the inwardmost portion44and the outwardmost portion46. A second maximum lateral distance D2is defined between the inwardmost portion44and the substantially flat portion28, asFIG. 2shows.

A ratio D1/D2of the first distance D1to the second distance D2is preferably substantially within a range of about 0.8 to about 1.2 and more preferably substantially within a range of about 0.9 to about 1.1.

Reinforcing rib34defines a boundary between the first, upper substantially flat portion28and the central concave portion32, and reinforcing rib42defines a boundary between the second, lower substantially flat portion30and the central concave portion32. In other words, the portion of the side panel20,22above the reinforcing rib34is preferably substantially flat, while the portion of the side panel20,22below the reinforcing rib34is preferably concave. Likewise, the portion of the side panel20,22below the reinforcing rib42is preferably substantially flat, while the portion of the side panel20,22above the reinforcing rib42is preferably concave.

FIG. 6is a finite element analysis (FEA) display indicating flexure of the container between the filled and unfilled states. It shows that the central concave portion32of the side panel20,22is permitted to flex, while the upper and lower substantially flat portions28,30substantially retain their shape. This facilitates adhesion of a label to the container10.