Patent Application
20070045216
b 1. Field of the Invention
The present invention relates generally to a container, and more particularly to a blow molded plastic container having a wide-mouth finish.
2. Related Art
Plastic containers for packaging are generally known in the prior art. Such containers may be used to package a wide variety of liquid, viscous or solid products including, for example, juices, other beverages, yogurt, sauces, pudding, lotions, soaps in liquid or gel form, and bead shaped objects such as candy. Generally, sealable plastic containers may include at least a closed end forming a base, a main body portion, a shoulder and a neck having a finish for accepting various types of closures thereon to seal the container.
Known plastic containers can differ from one another based on the sizes and shapes of the various portions of each container. For example, the bodies of many known plastic containers may have a cylindrical cross-sectional configuration but may also have rectangular cross-sections. Similarly, the finish portion of a container might be made larger or smaller than conventional finishes based on the particular application of the container. Wide-mouth containers, for instance, enable the consumer to scoop out viscous contents from within the container which do not readily flow. An example of a wide-mouth plastic container is disclosed in U.S. Pat. No. 6,555,191 to Smith et al., owned by the assignee of the present application, the disclosure of which is incorporated by reference.
Plastic containers may also differ based on the materials used therein or in the process of manufacture. In an exemplary stretch blow molding method of manufacturing blow molded plastic containers, for example, it is customary to utilize an injection molded preform having an injection molded threaded finish thereon. The injection molded finish on the preform ultimately forms the threaded finish of the container blown from the preform. Another exemplary method of forming a plastic container involves blow molding the entire container, including the threaded finish. In containers manufactured by extrusion blow molding techniques, the threaded finish is also blow molded, regardless of the size of the finish. Nevertheless, the methods of forming the containers and the resulting plastic containers themselves have various shortcomings.
Generally, quality plastic containers are not only sturdy, but also provide an air-tight seal when fitted with an appropriate closure. In order to create a good seal between the threaded finish of a container and a threaded closure, the threaded finish needs to be relatively rigid. Without such rigidity, the finish may be more prone to deflection such as, for example, ovalization, in a variety of settings. During processing, for example, threaded closures may initially be attached to the finish by axially punching them thereon. Without the necessary rigidity, the finish is likely to deflect during such attachment and a poor seal can result. Likewise, during cooling of a container (if hot-filled), a finish without the necessary rigidity may deflect and create sealing issues. Furthermore, finishes that lack rigidity might flex when squeezed or dropped during handling again resulting in improper sealing between the finish and the closure. Suitable finish rigidity may also be necessary during induction sealing to ensure a good induction seal. Each of the aforementioned scenarios can thus result in spoilage of the contents of the container because of the poor seal. Container finishes such as, for example, blown wide-mouth finishes, may often be excessively flexible and unable to create a good seal once a threaded closure is attached.
Prior art injection molded finishes often provide the necessary rigidity but may also require additional processing steps or include additional material. Typically, the required rigidity is achieved by either adding additional material to the finish portion of the preform, by altering the taper angle of the shoulder portion in the mold, or by increasing the crystallinity of the finish with respect to the container. These solutions provide the necessary rigidity, but detract from other aspects of the container. For example, by adding additional material to strengthen the finish of a container, both the weight and the cost of the container are increased. Likewise, altering the angled taper of the shoulder to provide necessary strength to the wide-mouth finish may ultimately detract from a desired aesthetic appearance of the container. Increasing the crystallinity of the finish can require additional steps in the manufacturing process. These configurations dictate a costly and inefficient manner of obtaining the required rigidity.
What is needed then is an improved plastic container having a finish that overcomes shortcomings of the aforementioned conventional solutions.
According to an exemplary embodiment of the instant invention, a finish of a plastic container is provided and may include an annular rib for increasing the rigidity of said finish. The annular rib may project radially inward on an internal surface of the container and may concurrently form a circumferential groove on an outer surface of the container.
According to a further exemplary embodiment of the instant invention, an improved wide-mouth plastic container is provided having a rigid finish that overcomes the shortcomings of the aforementioned conventional containers. The container may include a body having a shoulder, a base, and a neck having a finish. The finish may have a wide-mouth configuration. An annular rib may be provided between the finish and the shoulder, wherein the annular rib may increase the rigidity of the finish without requiring additional material or changes to the particular shoulder configuration of the container. The annular rib may further enable the finish to be rigid enough to accept a threaded closure to create a good seal therebetween without requiring preform redesign. In one exemplary embodiment, the finish may be a wide-mouth finish having a diameter of, for example, approximately 83 mm.
Further objectives and advantages, as well as the structure and function of exemplary embodiments will become apparent from a consideration of the description, drawings, and examples.
The foregoing and other features and advantages of the invention will be apparent from the following, more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings wherein like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.
Embodiments of the invention are discussed in detail below. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. While specific exemplary embodiments are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without parting from the spirit and scope of the invention.
Referring to the drawings,
Generally, a container 10 having the above-described construction requires a good seal between the finish 15 and the threaded closure in order to keep the contents of the container 10 fresh and/or preserved. This requires that the finish 15 of the container 10 be relatively rigid such that the threaded closure can properly seal the container 10. In the event that the finish 15 of the container 10 is large in size, for example, where the finish 15 has a “wide-mouth” construction, the finish 15 may be excessively flexible and unable to create a good seal once the threaded closure is attached. A wide-mouth finish 15 may be, for example, approximately 83 mm in diameter but the invention described herein may be applicable to a finish of any size where the ratio of finish diameter to finish material thickness is relatively large. Wide-mouth finishes may be generally considered to have diameters greater than approximately 48 mm.
The exemplary embodiment shown in
In an exemplary embodiment, the container 10 may include a wide-mouth finish 15 having a diameter of approximately 83 mm. The finish 15 may further have a wall thickness of between 0.039″ and 0.057″ as measured at unthreaded portions thereon. Without the annular rib, the finish of the container yields approximately 3.4 lbs. of resistance at a deflection of approximately 0.25 inches when placed sidelong in a top loading device. With the annular rib 17, however, the finish 15 of the container 10 yields approximately 10.7 lbs. of resistance at a deflection of approximately 0.25 inches when placed sidelong in the top loading device. Thus, including the annular rib 17 in a finish 15 such as, for example, a blown finish, may provide nearly three times the rigidity without requiring additional material.
In addition to the aforementioned advantages of the invention, the inwardly projecting circumferential groove formed by the annular rib 17 may provide a point of contact for use during processing. Typically, containers may have an outwardly projecting flange that can be gripped by container handling equipment to move and hold containers during processing. This outwardly projecting flange adds material to the container, however, thus increasing the weight and relative cost of the container. The circumferential groove provided by the present invention may also provide a contact point for container handling equipment, although the groove need not necessarily serve this function.
The container 10 may further have a generally one-piece construction and may be prepared from a monolayer plastic material, such as a polyamide, for example, nylon; a polyolefin such as polyethylene, for example, low density polyethylene (LDPE) or high density polyethylene (HDPE), or polypropylene; a polyester, for example, polyethylene terephthalate (PET) or polyethylene napthalate (PEN); or others, which can also include additives to vary the physical or chemical properties of the material. For example, some plastic resins can be modified to improve the oxygen permeability. Alternatively, the container 10 may be prepared from a multilayer plastic material. The layers can be any plastic material, including virgin, recycled and reground material, and can include plastics or other materials with additives to improve physical properties of the container. In addition to the above-mentioned materials, other materials often used in multilayer plastic containers include, for example, ethylvinyl alcohol (EVOH) and tie layers or binders to hold together materials that are subject to delamination when used in adjacent layers. A coating may be applied over the monolayer or multilayer material, for example to introduce oxygen barrier properties. In an exemplary embodiment, the present container 10 is prepared from PET.
The container 10 can be used to package a wide variety of liquid, viscous or solid products including, for example, juices, other beverages, yogurt, sauces, pudding, lotions, soaps in liquid or gel form, and bead shaped objects such as candy. The container 10 may be of cylindrical cross-sectional configuration. The body of the container 10, as formed, may be substantially tubular, but may have any cross sectional shape. Cross sectional shapes of the container 10 may include, for example, a circular transverse cross section, as illustrated; an oval transverse cross section; a substantially square transverse cross section; other substantially polygonal transverse cross sectional shapes such as triangular, pentagonal, etc.; or combinations of curved and arced shapes with linear shapes.
The container 10 can further be made by conventional blow molding processes including, for example, stretch blow molding and extrusion blow molding.
In stretch blow molding, a preformed parison, or preform, may be prepared from a thermoplastic material, such as by an injection molding process. The preform may include the threaded finish 15 and the annular rib 17. In another embodiment, however, the threaded finish 15 and annular rib 17 may be formed during blow molding. In either case, the preform may be positioned between two open blow mold halves. The blow mold halves close about the preform and cooperate to provide a cavity into which the preform is blown to form the container. After molding, the mold halves open to release the container. The container may then be sent to a trimmer where the moil, or extra plastic material above the finish, is removed.
In extrusion blow molding, a molten tube of thermoplastic material, or plastic parison, may first be extruded between a pair of open blow mold halves. The blow mold halves close about the parison and cooperate to provide a cavity into which the parison is blown to form the container. As formed, the container can include extra material, or flash, at the region where the molds come together. It may also include extra material, or a moil, intentionally present above the container finish. After the mold halves open, the container drops out and is then sent to a trimmer or cutter, not shown, where any flash of moil is removed. The finished container may have a visible ridge formed where the two mold halves used to form the container came together. This ridge is often referred to as the parting line.
The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art the best way known to the inventors to make and use the invention. Nothing in this specification should be considered as limiting the scope of the present invention. All examples presented are representative and non-limiting. The above-described embodiments of the invention may be modified or varied, without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the claims and their equivalents, the invention may be practiced otherwise than as specifically described.
