Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1998-11-09
2001-08-21
Dye, Rena L. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S034200, C428S035700, C428S066300, C428S066400, C428S349000, C428S461000, C428S464000, C428S513000, C215S232000, C215S341000, C215S344000, C215S347000, C215S350000
Reexamination Certificate
active
06277478
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a container closure system with an inner seal in a cap. The inner seal of the present invention is useful for use in closures of a wide range of sizes and types of containers in glass, plastics, metal and paper.
2. Description of the Prior Art
Various attempts have been made to prevent contamination and deterioration of contents in containers. For example, house instant coffee, creaming powder, soup stock cube, powdery cosmetics, and any other product which is hygroscopic or sells on its factory fresh flavor must be contained in a completely hermetic container so that it is prevented from being deteriorated by contacting with an ambient air or humidity before actually used by the user. For this purpose, the inner seal, which is sometimes referred to as “wadding tape” or “cap insert”, has been practically and widely used to hermetically seal the container mouth.
An example of the inner seal comprises a reseal liner of a relatively thick cardboard and a relatively thin paper-coated aluminum foil membrane that is easily separably laminated onto the reseal liner. The reseal liner is fitted within a cap whereas the membrane is glued or heat-sealed onto the container mouth. When the cap is removed from the container mouth, the membrane separates from the reseal liner and remains onto the container mouth, which is then peeled off so that the product in the container becomes accessible to the user. Even after the membrane has been removed, in-use protection of the product may be obtained by re-capping the container because the reseal liner within the cap will substantially hermetically seal the container mouth.
In accordance with the typical conventional sealing technique using the above-described inner seal, glue is applied to the rim of the container mouth and the container is capped in such a manner that glassine paper coated on the underside of the aluminum foil is placed over the glued rim, followed by natural cooling. Such conventional sealing technique is disclosed in Japanese Patent Publication Nos. 57-48466, 3-23429, 7-37268 and Japanese Utility-Model Publication Nos. 58-36685, 63-137756, for example.
However, it takes a long time, say. approximately one day, until glue on the rim is cured so as to completely close the container mouth, which means less productivity. Another disadvantage of this technique is that glue applied on the container mouth rim tends to be forced out to the inward or outward of the rim when capping. This is not only unattractive in commercial value but also unhygienic. When the container contains powdery product such as house instant coffee and powdery cosmetics, it would be attracted to and contaminated by the uncured glue remaining within the mouth of the container.
Recent trend of the sealing technique is to laminate thermoplastic resin film as the lowermost layer of the membrane. After capping, the cap is heated to a temperature above a melting point of the thermoplastic resin to provide hermetical closure to the container mouth. Such technique is disclosed in Japanese Utility-Model Publication No. 50-32540, 7-2451, 7-2452, 7-2453, Japanese Utility-Model Un-examined Publication Nos. 52-147652, 4-32958, Japanese Patent Un-examined Publication No. 4-72156, for example. The heat-sealing process in this technique is completed in a shorter period. However, the membrane is excessively strongly heat-sealed to the container mouth and, therefore, not easy to be peeled off by the user. Moreover, after the membrane is removed, at least a portion of the cured glue is deposited on the rim surface of the container mouth, which appears uncleanly and degrades reseal property when the container is capped with the cap having the reseal liner.
The inner seal is usually supplied in a continuous reel form in pre-determined widths on cardboard cores. The thermoplastic resin film used in the above-described conventional one has substantially a flat surface, which tends to result in a “blocking” when reeled.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the present invention to overcome the drawbacks and disadvantages of the conventional container sealing techniques, and more particularly to provide a novel construction of a inner seal for a container that is capable of completely hermetically and hygienically sealing a mouth of the container and still is easy to be peeled off and provides a satisfactory in-use protection of the product in the container.
In accordance with an aspect of the present invention, there is provided an inner seal for sealing a container mouth, said inner seal comprising a reseal liner fitted inside of a cap and a seal cover separably laminated to the reseal liner and remaining on the container mouth after the container is uncapped, the seal cover comprising a metal foil, a glassine paper layered on the underside of the metal foil, and a hot-melt adhesive layer coated on the underside of the glassine paper by gravure roll coating process. The metal foil and the glassine paper may be laminated each other by wet- or dry-lamination process. In a preferable embodiment of the present invention, a polyethlene film is layered between the metal foil and the glassine paper to provide a better peel-off strength therebetween. The glassine paper may be replaced with an easy-peelable plastic film, particularly PET (polyethlene terephthalate resin).
The reseal liner of the inner seal of the present invention may be a conventional one and comprises, for example, a cardboard of 300-800 g/m
2
in density or a foamed plastic film.
The inner seal of the present invention is characterized by laminated construction of the seal cover comprising the metal foil, the glassine paper (or any other easy-peelable layer plastic film such as PET film) layered on the underside of the metal foil, and the hot-melt adhesive layer coated on the underside of the glassine paper by gravure roll coating process. The glassine paper is preferably of 15-60 g/m
2
, which may be laminated on the metal foil such as an aluminum foil of 5.5-20 microns in thickness by interposing a polyethylene film therebetween. Then, a hot-melt adhesive is applied, in an amount of 10-50 g/m
2
, to the underside of the glassine paper by gravure roll coating process, followed by drying, to form the hot-melt adhesive layer. Using the gravure roll coating process will assure that the hot-melt adhesive layer thus formed on the bottom of the glassine paper has a rugged surface which is latticed depending upon the mesh structure of rolls used in the gravure roll coating equipment. Accordingly, when the inner seal of the present invention is wound on a reel, there are only point-to-point contacts between the top surface and the rugged bottom surface of the hot-melt adhesive layer, which prevents “blocking” therebetween.
The hot-melt adhesive is a mixture of an adhesive agent, ethylene-vinyl acetate copolymer (EVA) and a wax in a predetermined ratio, which is admixed in a known oven with rotary vanes. Wax decreases viscosity of the hot-melt adhesive to the order of 2000 cps at a temperature of 150 degrees in Centigrade. The hot-melt adhesive of the present invention has a melfing point ranging 65-140 degrees in Centigrade.
The upper surface of the metal or aluminum foil may be decorated as desired to increase appearance and commercial values of the inner seal. Such decoration may be printing of a company's logo, trade name or trademark of the product, any message or description that should be known to the user before the seal cover is removed from the container mouth. On a decorated or undecorated upper surface of the metal foil is coated a coating layer of peelable, hygienic material.
Thus, the seal cover of the inner seal of the present invention is prepared, and is laminated onto the bottom of the reseal liner to prepare the inner seal in accordance with the present invention. Of course, the inner seal should be cut into a predetermined shape and size for fitting in a cap. Since the seal cover is softly,
Kurita Keigo
Soutome Kiromi
Dann Dorfman Herrell & Skillman P.C.
Dye Rena L.
Taihei Paper Manufacturing
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