Patent Publication Number: US-6666001-B2

Title: Plastic container having an outwardly bulged portion

Description:
This application is a divisional of U.S. application Ser. No. 09/368,925, filed Aug. 5, 1999 (abandoned). 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention generally relates to plastic containers for beverages, particularly carbonated soft drink products and the like. More specifically, this invention relates to a blow molded plastic container, and to a method of forming that container, having at least one outward bulge immediately adjacent the body portion. This outward bulge portion has the practical effect of lending improved grip and manual handling characteristics to the container. 
     The use of plastic containers to package beverages, especially carbonated soft drink products, has been remarkably successful since such containers were first introduced in the 1970s. The widespread application of these containers primarily stems from the fact that the plastic material from which they are made can be biaxially oriented. These plastic materials, it may be noted, are invariably thermoplastics, most especially polyesters such as polyethylene terephthalate (PET). 
     Biaxial orientation involves aligning the polymer chains in two directions, and the consequence of this orientation is a closer, more orderly packing of material. The practical benefits of this phenomenon are two fold: first, containers thus oriented can be produced with thin walls, often as a direct result of the orienting process itself; and second, the mechanical strength and gas barrier properties of these thin wall containers increases dramatically upon biaxial orientation. The overall result is a container that is light weight, yet extremely robust. 
     A number of ways are known to fabricate these biaxially oriented containers. The most commercially important of these fabrication procedures, however, are those that employ stretch blow molding techniques. These techniques generally utilize a preform or parison, typically produced by way of injection molding, that is heated, or cooled, as the case may be, to at or near the glass transition temperature of the material. When at this temperature, the preform is placed into a blow mold in which the preform is longitudinally stretched by a stretch rod and horizontally expanded by air or other operating gas pressure. The resulting product is a container whose body and shoulder portions have relatively thin walls and are biaxially oriented. 
     Although the thin wall construction of biaxially-oriented containers is advantageous overall, there are, nevertheless, some drawbacks to this construction. For example, because of its thin nature, the container wall has little tolerance for a topical configuration that is other than smooth, uniform and continuous. Thus, even though it may be desirable to provide alterations or embellishments to the wall, it has been difficult to do so without adversely affecting the mechanical integrity of the wall. 
     Of the efforts made in this regard are those directed to providing the container walls with designs or features, such as ridges or ribs in the shoulder portions of such containers, in order to improve the consumer&#39;s ability to hold and handle the container. While important improvements have been made in this regard, the art still recognizes a continuing need to develop a container design or feature that will improve the consumer&#39;s ability to grip and handle the container and that will not detract from the mechanical integrity of the container. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to improve plastic, blow molded beverage containers. 
     Another object of the present invention is to provide a plastic, blow molded beverage container with improved handling characteristics. 
     A further object of this invention is to bulge outwardly one or both of the shoulder and base portions of a plastic, blow molded beverage container to make it easier to grip and to handle the container. 
     Another object of the present invention is to employ a greater than ambient pressure, present when a plastic, blow molded beverage container is filled with a beverage, to form two spaced apart bulges in the container that facilitate gripping and handling the container. 
     These and other objective are attained with a blow molded plastic beverage container, comprising a neck portion adapted to receive a closure, a body portion, a shoulder portion integrally connected to and extending between the neck portion and the body portion, and a base portion integrally connected to and extending from the base portion and closing a bottom end of the container. A bulge is formed in one, or both, of the shoulder and base portions bulging to facilitate gripping and handling the container. Preferably, a respective bulge is formed in each of the shoulder and base portions, forming a pair of bulges that bracket the container body. Also, preferably, grooves are formed in the shoulder and base portions of the container to facilitate formation of the bulges. 
     The container is formed in a multi-step process from a preform that may have a conventional design. In this process, the preform is expanded into an initial container shape having a neck portion, a shoulder portion, a body portion, and a base portion. That container is filled with a beverage, and a bulge is formed in one, or both, of the shoulder and base portions of the container. Preferably, the bulge or bulges are formed while the container is being filled with the beverage. For example, the container may be filled with a beverage at greater than ambient pressure, and this greater than ambient pressure may be used to bulge the shoulder and base portions outwardly of the container body. 
     Further benefits and advantage of the invention will become apparent from a consideration of the following detailed description, given with reference to the accompanying drawings, which specify and show preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 depicts a container embodying and made in accordance with the present invention. 
     FIG. 2 is a top view of the container. 
     FIG. 3 is a bottom view of the container. 
     FIG. 4 is a partial enlargement of a cross-section of the container illustrating details of grooves in a shoulder portion of the container. 
     FIG. 5 is a partial enlargement of a cross-section of the container showing details of grooves in a base portion of the container. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 depicts container  10  comprising a neck portion  12  adapted to receive a closure, a shoulder portion  14 , a body portion  16 , which is generally tubular in shape, and a bottom or base portion  20 , which may be of either the petaloid or champagne push-up type, petaloid being depicted. As will be appreciated by those of ordinary skill in the art, for purposes of the present invention, the bottom portion  20  may also be outwardly hemispherical, which normally requires the conjoint use of a base cup. The particular container  10  illustrated has a size of about 1500 ml. 
     As discussed in greater detail below, container  10  is made by the blow molding a preform into an initial shape, shown in full lines in FIG. 1, and then bulging out, preferably, both the shoulder and base portions into a final shape, shown in broken lines in FIG.  1 . More specifically, in the bulged shape, shoulder portion  14  and base portion  20  both bulge outwardly of body portion  16 —that is, the shoulder portion and the base portion form respective bulges  22  and  24 , both of which project outwardly of the cylinder defined by the body portion  16 . In the bulged state, shoulder portion  14  has a dome shape and includes an upper portion  26  and a lower, truncated spherical portion  30 . Upper portion  26  extends downwardly outwardly from neck portion  12 . Truncated spherical portion  30  has a generally uniform radius of curvature and a horizontal midsection  32  defining a maximum diameter of the truncated spherical portion. Truncated spherical portion  30  extends downwardly outwardly, at the above-mentioned generally uniform radius of curvature, from upper portion  26  to midsection  32 . Portion  30  then extends downwardly inwardly, also at this radius of curvature from midsection  32  to body portion  16  of container  10 . 
     In to bulged state, base portion  20  includes a lower portion  34  and an upper, truncated spherical portion  36 . Truncated spherical portion  36  has a generally uniform radius of curvature and a horizontal midsection  40  defining a maximum diameter of the truncated spherical portion. Truncated spherical portion  36  extends downwardly outwardly, at the above-mentioned generally uniform radius of curvature, from body portion  16  to midsection  40 . Portion  36  then extends downwardly inwardly, also at this radius of curvature from midsection  40  to lower base portion  34 . 
     Preferably, a plurality of grooves are formed in both the shoulder and base portions  14  and  20  to facilitate forming bulges  22  and  24 . As illustrated in FIG. 1, the grooves  46  formed in the shoulder portion  14  extend along substantially the entire length of the shoulder portion and have termini proximate neck portion  12  and termini proximate body portion  16 . Preferably these grooves  46  are in the form of a spiral, the particular embodiment illustrated showing the spiral diverging as it proceeds from that part of the shoulder portion  14  proximate neck portion  12  to that part proximate body portion  16 . 
     With reference to FIGS. 1,  2  and  4 , grooves  46  are circumferentially disposed about shoulder portion  14 , and the grooves are spaced apart and separated from one another by an angle α, which is formed by two radii of the shoulder portion that bisect adjacent grooves. Also, as illustrated in FIGS. 1,  2  and  4  preferably the outer surface of the shoulder portion  14  between each of the grooves  46  is substantially smooth. 
     As particularly shown in FIG. 2, shoulder portion  14  has twenty grooves  46 . 
     The grooves  50  formed in base portion  20  have a curved shape, and are equally spaced around the circumference of the base portion. As illustrated in FIG. 1, the grooves  50  formed in the base portion  20  extend along substantially the entire length of the outer side of the base portion and have upper termini proximate body portion and lower termini. With reference to FIG. 5, grooves  50  are spaced apart and are separated from one another by an angle B, which is formed by two radii of base portion. 
     As will be understood by those of ordinary skill in the art, numerous modifications may be made to the specific container design shown in FIGS. 1-3. For example, and without limitation, the number and spacing of the grooves  46  and  50  may vary. Also, the grooves  46  and  50  may extend along only a part of the length of the shoulder and base portions  14  and  20 . Moreover, the lengths of the shoulder and base portions themselves can vary depending upon the size and other conformational characteristics of the container. Preferably, for example, the shoulder length is generally equal to about 30% of the total height of the container. 
     Container  10  is formed in a multi-step process from a preform that may have a conventional design. More specifically, the preform is expanded into an initial container shape, shown in full lines in FIG. 1, having a neck portion, a shoulder portion, and a body portion. That container is filled with a beverage, and the shoulder and base portions of the container are bulged outwardly of the body portion to form the bulges  22  and  24  of container  10 . Preferably, these bulges are formed while the container is being filled with the beverage. For example, the container may be filled with a beverage at greater than ambient pressure, and this greater than ambient pressure may be used to bulge the shoulder and base portions  14  and  20  outwardly of the container body  16 . In addition, preferably, grooves  46  and  50  are formed in shoulder and base portions  14  and  20  as the preform is expanded into the initial container shape shown in full lines in FIG.  1 . 
     Conventional fabrication techniques, well known in the art, may be employed in the practice of this invention. Of the more preferable methods in this regard is stretch blow molding, using a preform or parison of convention design and a blow mold where the aspect of the mold that corresponds to the shoulder and base portions of the initially formed container is configured so as to produce the shoulder and base portions, preferably including grooves  46  and  50 . As will be appreciated by those of ordinary skill in the art, the present invention may be implemented in containers of any size, including, without limitation, sizes commonly found in commercial use such as from 0.33 liter to 2.0 liters and larger. 
     In practice, the present invention can be successfully implemented in containers having thin wall portions. In general, the wall thickness of shoulder portions contemplated in this regard are from about 0.22 mm to about 0.35 mm, more typically from about 0.25 mm to about 0.28 mm. As will be appreciated by those of ordinary skill in the art, this magnitude of wall thickness is commonly employed in non-returnable beverage containers, also known as one-way or disposable containers. The present invention need not be limited to such containers, however. 
     While any plastic material suitable for use with beverages, including soft drink products and the like, may be employed in the practice of this invention, it is preferred as a practical matter that thermoplastics, more preferably polyesters, be employed. The most preferred polyester material in this regard is polyethylene terephthalate, or PET. PET as contemplated herein includes homopolymer PET and copolymer PET including, without limitation, those copolymers wherein the ethylene glycol component has been replaced, in part, with e.g., cyclohexane dimethanol, and those wherein the terephthalic acid component is replaced, in part, with, e.g., isophthalic acid. As those of ordinary skill in the art will recognize, the intrinsic viscosity of the PET can vary depending on considerations of use, setting and container conformation, and is generally greater than about 0.55, usually greater than about 0.75. and most commonly about 0.80 to 1.00. 
     While it is apparent that the invention herein disclosed is well calculated to fulfill the above stated objects, it will be appreciated that numerous modifications and embodiments may be devised by those skilled in the art, and it is intended that the appended claims cover all such modifications and embodiments as fall within the true spirit and scope of the present invention.