Patent Application
20080093330
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.
An exemplary container 100 according to the present invention is illustrated by
As shown by the Figures, finish base 104 is adjacent to and slopes downwardly away from neck finish 102 at a second angle β, and towards shoulder 108. The angle β is defined with respect to a plane that is perpendicular to the longitudinal axis LA of the container 100 (see
Both the finish base 104 and the shoulder 108 each have a wall thickness. (See
As most clearly visible in
Factors that may affect angles α, β and γ are, for example, the flowability of the manufacturing material and the cooling properties of the material (e.g. how quickly the material cools.) Angles β and γ in particular can help with the flow of the material, and can be altered based on the properties of the plastic being used and the desired specifications, dimensions, and/or uses of the container to be produced.
In order to maintain container integrity, especially with respect to the finish area 112 that includes the neck finish 102, finish base 104 and shoulder area 108, step or finish ring 106 is inserted between the finish base 104 and the shoulder 106. The step/finish ring 106 contributes to uniform distribution of material in the manufacturing process. For example, the addition of the step 106 allows hot plastic to flow into the region of the step 106 and aid in material distribution as the plastic is stretched and blown to form the container 100. The angle γ assists with the flow of plastic into the step 106.
The step also has a height HS (
The distribution of plastic material in the finish area 112 is at least partly determined by the height of the step. The greater the step height HS, the more material that flows into the finish area 112. Thus, if it is advantageous for a container to have increased strength in the upper portion of the container (including the finish area 112), the height of the step HS can be increased so that more plastic is present in the finish area 112.
The container according to some embodiments of the invention described herein can be an inverted-style container. An inverted container may need more strength in the upper portion of the container to support the weight of the container and contents without collapse. The increased material and strength imparted by step 106 to the finish area 112 allows the finish area to maintain perpendicularity and stay level. The ability to maintain perpendicularity is of special importance in inverted style containers. Also, the increased strength imparted by the step can enhance top loading ability for all containers. The container of the present invention can also be adapted for use with wide-diameter closures.
In order to provide a complete idea of the container as described herein, the following are measurements according to one exemplary embodiment, such as that shown in
Certain embodiments of the present invention are further related to a method of maintaining perpendicularity of a finish of a blow molded container by providing the container described herein. Containers, particularly containers having a finish area with a large diameter, are susceptible falling on one side, thus becoming crooked. This problem is often experienced with inverted-style containers, that may droop to one side due to weakness in the finish area. Falling or tilting can result from uneven cooling of the plastic material due to uneven distribution of plastic in the finish area 112. By providing the container with finish area 112 having step 106 as set forth in the present invention, material is distributed more evenly, cools more evenly, and this prevents collapse of the finish area 112 on one side. Thus, perpendicularity of the finish area 112 is maintained.
Embodiments of the present invention are additionally related to a finish area 112 for a blow molded container, as most clearly shown in
Embodiments of the invention as described herein can be particularly advantageous in containers where the finish area 112, has a large diameter. For example, containers having an extended finish base 104 where the length of the finish base LF is longer than is many standard containers, can be improved by manufacture using the method described herein. For example, one challenge currently experienced in manufacturing is that the finish area can collapse upon itself or recede in the direction of the container body. Such a dent or recession can reduce the distance between the finish and the shoulder. A reduction in this distance can create problems with respect to closure clearances. The addition of a step or finish ring 106 to finish area 112 contributes to uniform distribution of plastic material in finish area 112 and can assist in overcoming some of the difficulties encountered during manufacture. The angled step 106 slows the material flow so that a greater amount of plastic is retained in finish area 112. After blow molding, the finish area 112 of the container 100 is thicker and has increased strength. This prevents the finish area 112 from tilting to one side and/or collapse of the container under pressure. The addition of the step/finish ring 106 stabilizes the finish area which can increase the cycle time of manufacture.
The container 100 has a one-piece construction and can 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), polyethylene naphthalate (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 can 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 is prepared from PET.
The container can be manufactured by blow molding, such as extrusion blow molding, stretch blow molding, and injection blow molding. In extrusion blow molding, A molten tube of thermoplastic material, or plastic parison, is 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, or extra material, or a moil, intentionally present above the container finish. After the mold halves open, the container drops out and is then went to a trimmer or cutter 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.
In stretch blow molding, a preformed parison, or preform, is prepared from a thermoplastic material, typically by an injection molding process. The preform typically can include threaded end, which becomes the threads of the container. Alternatively, the threaded finish can be formed during blow molding. The perform is positioned between two open blow mold halves. The blow mold halves close about the perform 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 can then be sent to a trimmer where the moil, or extra plastic material above the blown finish, is removed.
In injection blow molding, a thermoplastic material is extruded through a rod into an inject mold to form a parison. The parison is positioned between two 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. After molding, the mold halves open to release the container.
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.
