Receptacles – Closures – Pivotable
Reexamination Certificate
2000-11-15
2003-08-26
Newhouse, Nathan J. (Department: 3727)
Receptacles
Closures
Pivotable,
C220S004230
Reexamination Certificate
active
06609633
ABSTRACT:
FIELD OF THE INVENTION
This invention pertains generally to the field of plastic packaging and particularly to thermoformed plastic containers.
BACKGROUND OF THE INVENTION
Reclosable plastic containers are used for the packaging of a wide variety of products which will be held in the container and utilized by the consumer over a period of time. The containers may be utilized to enclose and protect products that are periodically used, such as a compact disk, a videotape, an audio tape, etc., or to contain multiple products which are used by the consumer one at a time, e.g., diapers, paper napkins, disposable wipes, screws, fasteners, etc. The cover for such reclosable containers is typically connected to a receptacle by a hinge about which the cover rotates when opened by the consumer to permit access to the interior of the container.
Various production processes are used to form plastic containers. Injection molding is well suited to the formation of relatively thick-walled, rigid plastic containers of the type that are intended for long-term use by the consumer. A variety of hinge structures are possible in injection molded containers because of the flexibility offered by the injection molding process. However, injection molding is not economically well suited to the production of plastic containers intended for use in the packaging of relatively low cost products. The molds used in injection molding processes are expensive, and the injection molding process itself is a relatively slow production process involving complex equipment which must be carefully monitored and controlled.
For the production of relatively low cost plastic containers for use in the packaging of bulk or relatively inexpensive consumer products, the thermoforming process is more widely used. In the thermoforming process, a thin sheet of thermoplastic is held over a mold and is heated to a temperature at which it can be plastically deformed. The heated plastic is then drawn using vacuum and pressure into the mold where it conforms to the surfaces of the mold, cools, and hardens to retain the shape of the mold. The formed product can then be die cut from the surrounding sheet, removed from the mold, and a new section of plastic sheet advanced into place over the mold. This thermoforming process, and variations on it, can be carried on in a continuous production process, allowing very high production volumes and low unit costs. These processes are used to form the common “blister packs” in which a product is sealed between the formed plastic “blister” and a removable panel, commonly of paperboard. Such blister packaging is relatively inexpensive and is typically discarded after the package is opened by the consumer.
Reclosable hinged plastic containers may also be made by the thermoforming process. Typically, the receptacle of the container and the cover are formed integrally from the same sheet of plastic and are joined together by a so-called “living hinge” which flexibly joins the cover and the receptacle. The plastic of the living hinge is sometimes thinned during the forming process to make it more flexible. While such integrally formed reclosable containers can be made very economically, and are extensively used in the packaging of a wide variety of products, the integral cover and receptacle structure has certain inherent limitations. Generally, the cover and receptacle must be formed of the same plastic. Although it is possible to thermoform containers having a different plastic material for the cover and the receptacle, by utilizing a sheet of two separate plastics joined together, the choice of plastics that can be used is limited and the requirement for special plastic sheet stock makes the process less economical. Furthermore, some types of common plastics are not well suited to be formed with a living hinge because of the inherent rigidity or vulnerability to fatigue failure of the plastic material. Polystyrene is an example of a type of plastic commonly used in packaging but not well suited to the use of an integral living hinge. Containers formed with living hinges may also suffer from a bias or memory in the hinge which tends to draw the cover partially open. In certain situations, it may be disadvantageous to utilize containers with integrally formed covers, for example, where the cover is to be printed, labeled or decorated after forming, or where the cover may interfere with or complicate the automated filling of the receptacle with the end product.
Thus, it would be desirable to be able to produce containers by the thermoforming process in which the cover and receptacle were formed separately and then joined later by hinge structures formed in the cover and receptacle during the thermoforming operation. However, the thermoforming process is not well suited to the formation of structures of the type that would be analogous to the hinge pins and pivots that are utilized in, for example, reclosable injection molded containers. Because the thermoforming process utilizes a plastic sheet which has been softened by heating (but is not a liquid), the process is not well suited to form small projections or other structures that are sharply defined and have relatively small dimensions.
SUMMARY OF THE INVENTION
In accordance with the invention, a reclosable thermoformed hinged container has a separate cover and receptacle which are both produced by the thermoforming process in an efficient and economical manner. If desired, the cover and receptacle can be made of different plastic materials, of different gauge materials, in different colors and with different finishes. The separate cover and receptacle are well suited for compact shipping from the point of production of the container to the point of assembly where the receptacles are filled with the end product, since the separate cover and receptacle can be nestably stacked to provide a very compact product for shipment with minimal dead air space. The separate forming of the cover from the receptacle allows the cover to be formed with graphical material embossed therein utilizing processing conditions (e.g., heating temperature, dwell times in the mold, etc.) different from that required for forming the receptacle, and the cover is well suited to being decorated before it is assembled to the receptacle.
In accordance with the invention, hinge structures are formed in the cover and receptacle during the thermoforming process in which the cover and receptacle are separately produced. These hinge structures are formed in a manner which does not require disruption or modification of the normal thermoforming process sequence. The receptacle has an open top and is formed of a thermoformed sheet of plastic material having a hinge edge at its top, a hinge flange extending outwardly from the hinge edge, side skirt walls extending from the hinge flange generally perpendicular to the hinge edge, and an indentation formed in each side skirt wall. The cover is formed of a thermoformed sheet of plastic material and has a hinge edge, a hinge flange extending outwardly from the hinge edge, side skirt walls extending from the hinge flange generally perpendicular to the hinge edge, and an indentation formed in each of the side skirt walls of the cover. The indentations are formed in the side skirt walls of each of the receptacle and the cover along an axis of rotation. The indentations on one of the cover or the receptacle form hinge pins which, when the cover is assembled onto the receptacle, seat in the indentations in the side skirt walls of the other of the cover or receptacle to define a hinge at the axis of rotation. Assembly of the cover to the base receptacle can be easily carried out by pressing the cover onto the receptacle until the hinge pins snap fit and seat into the indentations.
In a preferred construction for the container, the hinge flange on the cover is formed to fit over the hinge flange on the receptacle, with the side skirt walls of the cover extending down over and adjacent to the side skirt walls of the receptacle. The indentations in the
Dyble Richard J.
Gottschall Steven J.
Stamm Edward A.
Foley & Lardner
Newhouse Nathan J.
Panoramic, Inc.
LandOfFree
Reclosable thermoformed hinged container does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reclosable thermoformed hinged container, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reclosable thermoformed hinged container will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3096229