Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
1994-09-16
2001-07-10
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S254000, C264S275000
Reexamination Certificate
active
06258312
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a container closure and more particularly to a novel method for producing a container closure for containers for liquids and solids, such as food and beverages.
Heretofore a large percentage of food and beverage containers have been formed of metal can bodies which have one or both ends thereof closed by a metal can end double seamed to a flange of the container for forming a hermetically sealed container. Such containers, while generally satisfactory, do have various shortcomings. For example, some metal containers are formed of thin metal which can be easily dented, which at times detracts from their marketability. Further, such containers must be protected with various coatings and/or sealants which need to be carefully selected to be compatible with the contents, thus adding to the costs and difficulties of manufacturing as well as creating a need for a large variety of processes and inventory. In addition, metal containers are plagued with sharp metal edges after being opened.
SUMMARY OF THE INVENTION
The invention comprises a closure member for a container, and the combination thereof, wherein the closure is formed of multiple parts which include a frame member preferably molded from a thermoplastic material. The frame member includes one or more depending skirts, or flanges, which may be snapped onto and then permanently bonded to the flange of a metal, glass or plastic container. The frame member is annular, i.e., ring-like, and conforms to the shape of container whether it be round, square, triangular, elliptical or of some other cross-section. The central, open portion of the frame member is preferably provided with a disk portion which is adhered to, or bonded to, the frame member as part of an insert-injection molding process in which the previously formed disk member is placed within a mold and the frame member is formed and adheres to the disk member. Depending upon the choice of materials for the frame member and disk member, the interface of the two members, while strong enough to structurally seal the container and hold the product, can be easily separated by peeling the disk member away from the frame member for gaining access to the product within the container.
The materials of the disk and frame members may be selected such that the heat and pressure of the frame molding operation will create a bond therebetween but it is within the scope of the invention that the interface between these two members can contain a layer or coating of an adhesive material or the interface can be sealed with a film or a foil. In order to assist in peeling the disk member from the frame member, the disk member is provided with a pull tab that can be in the form of a pull ring for providing a sure grip.
In view of the foregoing, it is an object of the invention to provide a closure for a container, the closure including a frame member and an end panel, means attaching the end panel to the frame member, the frame member comprising an injection molded plastic article including means for securing the frame member and the end panel to a container, and means for peeling the end panel from at least a portion of the frame member.
A further object of the invention is to provide such a closure which is comprised of at least one layer of plastic material and includes a pull tab integrally formed therewith.
A further object of the invention is to provide such a closure wherein the end panel is comprised of multi-layers adhered together and including top and bottom layers of polypropylene and an inner layer ethylene vinyl alcohol, and adhesive means for adhering the multi-layers together into a unitary panel.
A still further object of the invention is to provide a method of forming a container closure including the steps of forming an end panel in the shape of a planar disk; inserting the disk into a mold having a mold cavity for forming a frame member shaped to be secured to the flange of a container; and injecting plastic material into the mold cavity for forming the frame member and for attaching the end panel to the frame member.
An additional object of the invention is to provide a method as set out above wherein the step of forming the end panel includes the step of providing a pull tab extending co-planar with the disk, and wherein the step of forming the frame member includes the step of providing the frame member with an upstanding rib means extending about an upper surface of the frame member for facilitating stacking of a plurality of the closures and for protecting the pull tab.
An even further object of the invention is to provide the method described above with a step of forming a securing strip as part of the frame member for fixedly securing a portion of the end panel to the frame member.
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Holt William H.
Ortiz Angela
Polystar Packaging, Incorporated
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