Patent Application
20100006535
1. Field of the Invention
The present invention relates generally to plastic containers, such as the plastic containers that are commonly used to package beverages and other liquids.
2. Description of the Related Technology
Many products that were previously packaged using glass containers are now being supplied in plastic containers, such as containers that are fabricated from polyesters such as polyethylene terephthalate (PET).
PET containers are lightweight, inexpensive, recyclable and can be economically manufactured in large quantities. PET therefore possesses excellent characteristics for containers, but PET resin is relatively expensive. Accordingly, a PET container design that reduces the amount of material that is used without sacrificing performance will provide a significant competitive advantage within the packaging industry.
PET containers are typically manufactured using the stretch blow molding process. This involves the use of a preform that is injection molded into a shape that facilitates distribution of the plastic material within the preform into the desired final shape of the container. 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 takes 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.
PET containers are particularly common for use in packaging beverages such as juices using what is known in the industry as the hot-fill process. This involves filling the containers while the liquid product is at an elevated temperature, typically 68° C.-96° C. (155° F.-205° F.) and usually about 85° C. (185° F.) in order to sterilize the container at the time of filling. Containers that are designed to withstand the process are known as “hot fill” or “heat set” containers. Hot fill containers must be designed to be strong enough in the areas outside of the vacuum panel regions so that the deformation that occurs as a result of the volumetric shrinkage of a product within the container is substantially limited to the portions of the container that are designed specifically to accommodate such shrinkage. In addition, since filled containers are often stacked on top of one another for transportation and distribution, the sidewall of such containers must be designed to have sufficient column strength in order to endure a predetermined minimum vertical load. It is important that such column strength not be degraded as the shape of the container changes as result of volumetric shrinkage within the container.
The dome is the upper portion of the container adjacent the finish. Some dome configurations are designed to have a transverse cross-section which is generally circular in shape or “bell-shaped”. Other dome configurations are designed to possess a transverse cross-section that is substantially rectangular in shape. Both types of dome configurations may have a rounded upper shoulder portion near the container neck. The diameter of the transverse cross-section through a dome will typically increase as the dome extends downwardly from the container neck or finish portion. In some containers, the dome diameter then decreases to an inwardly extending peripheral waist, and downwardly from the waist, the dome diameter increases before connecting with the label mounting area or main body portion of the container.
In many container designs, the dome is the weakest link in terms of the column strength of the container. In order to minimize material costs, desirable to make the sidewall of the container dome, as with the rest of the container, as thin as possible. However, such lightweighting comes at the expense of container strength, and in particular column strength. Efforts have been made to reinforce some types of container domes in order to enhance their strength. For example, U.S. Pat. No. 5,222,615 issued to Ota et al. discloses a container having a rectangular, horizontal cross-section with a dome and support panels to increase the strength of the container and compensate for unequal stretching of the container during blow-molding. Another known container that incorporates a degree of dome reinforcement is U.S. Pat. No. 5,067,622 issued to Garver et al., which discloses a hot-fillable PET container having support panels located below the waist of its bell-shaped dome to accommodate deformation due to the vacuum effect caused by hot-filling. U.S. Pat. No. 5,310,068 issued to Saghri discloses a collapsible container having panels spaced along the periphery of its dome. U.S. Pat. Nos. 5,238,129 and 5,178,290 issued to Ota et al.; 4,805,788 issued to Akiho; 5,199,588 issued to Hayashi; 4,946,053 issued to Conrad; and 4,818,575 issued to Hirata et al. also disclose the use of panels in the dome portion of a container.
However, many such designs insufficiently augment the column strength of the container. In addition, the prior art designs in many cases are not effectively applicable to dome configurations that possess a transverse cross-section that is substantially rectangular in shape. Moreover, many of these prior art designs are aesthetically unattractive.
A need exists for an improved domed container that possesses optimal column strength that is particularly suitable for use with containers that possess a transverse cross-section that is substantially rectangular in shape, and that is aesthetically attractive.
Accordingly, it is an object of one facet of the invention to provide an improved domed container that possesses optimal column strength.
It is an object of another facet of the invention to provide an improved domed container that is particularly suitable for use with domed containers that possess a transverse cross-section that is substantially rectangular in shape.
It is an object of yet another facet of the invention to provide an improved domed container that is aesthetically attractive.
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 sidewall having an outer surface and an inner surface, the sidewall being shaped to define a container neck; a main body portion; and a dome that is substantially rectangular in transverse cross-section, the dome having a lower end that is integral with the main body portion and a shoulder at an upper end that is integral with the container neck, and wherein the dome includes at least one longitudinally extending buttress column defined in said sidewall that when viewed in transverse cross-section protrudes laterally outwardly from adjacent portions of the sidewall, whereby the strength of said container is enhanced.
According to a second aspect of the invention, a plastic container may include a sidewall having an outer surface and an inner surface, the sidewall being shaped to define a container neck; a main body portion; and a dome having a lower end that is integral with the main body portion and a shoulder at an upper end that is integral with the container neck, and wherein the dome includes at least one longitudinally extending buttress column defined in the sidewall that when viewed in transverse cross-section protrudes laterally outwardly from adjacent portions of the sidewall, the at least one longitudinally extending buttress column extending along an entire length of the dome from the main body portion to said container neck whereby the strength of the container is enhanced.
These and various other advantages and features of novelty that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.
Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to
Plastic container 10 in the preferred embodiment is a hot fill type container, although the invention has applicability for containers that are not of the hot fill type.
Plastic container 10 includes a sidewall 12 having an outer surface and an inner surface that defines an interior space in which a product such as a beverage or any one of a multiplicity of different types of liquids or solids may be packaged. The sidewall 12 is shaped so as to define a container neck 14, which in the illustrated embodiment is configured as a threaded finish portion that is adapted to receive an internally threaded closure. A sidewall 12 is further shaped so as to define a main body portion 16 that forms a bottom and a lower end of the plastic container 12. The main body portion 16 in the illustrated embodiment includes a relatively flat or slightly convexly curved label panel 18 that is provided with a plurality of horizontally oriented reinforcing ribs 20. Main body portion 16 further includes a pair of side vacuum panels 22 in which a plurality of horizontally oriented reinforcing ribs 24 are provided. Main body portion 16 is configured so that it is substantially rectangular in transverse cross-section.
Plastic container 10 is configured as a domed container, and includes a dome portion 26 that in the preferred embodiment is substantially rectangular in transverse cross-section. Dome portion 26 accordingly has front and rear surfaces 52, 54 and side surfaces 56, 58 that are smaller than the front and rear surfaces 52, 54. In the preferred embodiment, the front and rear surfaces 52, 54 are provided with gripping indentations 30 that are shaped so as to enable a consumer to securely grip the plastic container 10 using a pinching action with the thumb and forefinger. The gripping indentations 30 are preferably positioned so that their adjacent to the lower end 34 of the dome portion 26. The front and rear surfaces 52, 54 also preferably include a display area 32 in which some type of a display pattern such as a manufacturer's logo or trademark may be embossed. The display area 32 is preferably relatively flat and is preferably located in an intermediate portion of the container dome 26 between the gripping indentation 30 and an upper shoulder portion 38 of the container dome 26.
The dome portion 26 has a lower end 34 that is integral with the main body portion 16 and the aforementioned shoulder 38 at an upper end 36 that is integral with the container neck 14. A narrowed waist portion 28 may be provided between the dome portion 26 and the main body portion 16. The shoulder 38 preferably has an outer surface that is slightly convex, and is tapered so that its transverse cross-sectional area becomes reduced as it transitions upwardly to the interface with the container neck 14.
One particularly advantageous feature of the plastic container 10 is that includes at least one longitudinally extending buttress column defined in the sidewall of the container dome 26 that when viewed in transverse cross-section protrudes laterally outwardly from adjacent portions of the sidewall, thereby enhancing the strength of the container 10. In the preferred embodiment, plastic container 10 includes a pair of longitudinally extending buttress columns 40, 42, which are provided respectively on the side portions 58, 56 of the plastic container 10. Longitudinally extending buttress columns 40, 42 are preferably symmetrically opposed to each other and are further preferably symmetrical in shape in order to provide symmetric reinforcement of the column strength of the plastic container 10.
Preferably, both of the buttress columns 40, 42 extend along an entire length of the shoulder portion 38. More preferably, both of the buttress columns 40, 42 also extend along a part of the container dome 26 that does not define the shoulder portion 38. In the illustrated preferred embodiment, both of the buttress columns 40, 42 extend for an entire length of the container dome 26 from the interface with the main body portion 16 upwardly to the interface with the container neck 14.
Preferably, at least a portion of both of the buttress columns 40, 42 is tapered in width so as to be narrower at an upper end than it is at a lower end. In the illustrated embodiment, both of the buttress columns 40, 42 include a first tapered portion 46 that is located near a lowermost end 34 of the container dome 26 and has a relatively broad base of a lower end that is adjacent to the main body portion 16 and is tapered so as to narrow as it extends upwardly. Both of the buttress columns 40, 42 in the illustrated embodiment further include a second tapered portion 48 that is located on the shoulder portion 38 of the container dome 26 and that is tapered so as to narrow as it extends upwardly to an upper end that is adjacent to the container neck 14. The illustrated buttress columns 40, 42 further include a central portion 50 that is integral in continuous with an upper end of the first tapered portion 46 and a lower end of the second tapered portion 48.
Preferably, the longitudinally extending buttress columns 40, 42 are configured to have the pleasing aesthetic appearance of discrete bands or belts that extend longitudinally along the narrow sides 56, 58 of the plastic container 10 upwardly, traversing the shoulder portion 38 to the interface between the container dome 26 and the container neck 14. The buttress columns 40, 42 are unitary portions of the sidewall that defines the shape of the plastic container 10 and preferably have sidewall thickness that is not substantially different than the sidewall thickness of the rest of the container dome 26.
The buttress columns 40, 42 are preferably shaped so as to be generally C-Shaped as viewed in transverse cross-section, and have broad outer surface 44 that is substantially flat, although it might have a slight convexity.
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
