Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
1999-02-26
2001-05-22
Gupta, Yogendra (Department: 1751)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S352000, C428S354000, C428S910000, C428S343000, C428S040600, C428S042100, C428S35500R, C428S507000, C428S511000, C428S214000
Reexamination Certificate
active
06235386
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
This invention relates generally to pressure-sensitive sealing tapes, and more particularly to a paper-plastic film laminate tape of exceptional strength and sufficient body to enable the tape to be dispensed in a conventional tape dispenser machine.
2. Status of the Prior Art
The patent to Williams 4,351,877 discloses a sealing tape for cartons, formed of a high-strength face ply of synthetic plastic film material, laminated to a base ply of paper whose outer surface is coated with a remoistenable adhesive. This tape is wound into a roll and is dispensed from a standard Kraft paper tape-dispensing machine which includes a water reservoir to moisten the adhesive coating as the tape is advanced out of the dispenser.
As pointed out in the Williams patent, though a sealing tape formed from a thin film of synthetic plastic material is much stronger than a Kraft paper tape, particularly if the film tape is stretch-oriented, a roll of such film tape cannot be dispensed in a Kraft paper tape-dispensing machine.
The reason for this is that the machine relies on the longitudinal stiffness of the paper tape to unwind it from the roll and force it through the outlet of the dispenser where the tape is cut to a desired length. A thin plastic film is unable to be dispensed lengthwise from a Kraft paper or a similar dispenser machine because the flexible plastic film tape is inherently flabby and lacks sufficient rigidity or stiffness for this purpose.
In order, therefore, to add sufficient rigidity to the tape so that it can be properly dispensed, Williams laminates a paper ply to the plastic film ply. To effect lamination of the paper ply to the plastic ply, Williams uses a conventional glue for this purpose. Should this glue be a hot melt adhesive of the type ordinarily used to laminate paper to film, the resultant heat would impair the orientation and strength of the film.
Our parent U.S. Pat. Nos. 5,780,150 and 5,804,024 disclose a paper-film laminate sealing tape having a base ply of oriented film, cold-laminated by a water-based adhesive to a paper face ply so that its orientation is maintained, the exposed surface of the film base ply being coated with a remoistenable adhesive. The present invention resides in a pressure-sensitive paper-plastic film laminate tape which is applied to a surface to be sealed by pressure as distinguished from a tape, as in Williams, and in our earlier application in which the adhesive layer is remoistenable.
SUMMARY OF THE INVENTION
In view of the foregoing, the main object of this invention is to provide a paper-plastic film laminate pressure-sensitive sealing tape of exceptional strength and of sufficient body to enable the tape to be dispensed in a conventional pull-and-tear tape dispenser.
More particularly an object of the invention is to provide a tape of the above type in which a plastic film ply biaxially-oriented to impart high-strength thereto, is cold laminated to the paper ply by a water-based adhesive so, that lamination is effected without heat that would impair the orientation and strength of the plastic film ply.
A significant feature of a tape in accordance with the invention is that it is highly-resistant to delamination and when stripped from a carton or other article, it is removed therefrom in toto.
Briefly stated, these objects are attained in a pressure-sensitive tape for sealing cartons and for other applications requiring a flexible tape of exceptional strength and of sufficient body so that the tape in roll form may be dispensed from a conventional pull-and-tear tape dispenser.
In a first embodiment, the invention is directed to a pressure sensitive sealing tape product adapted to adhere to various items in applications involving taping and sealing, and having sufficient body to permit dispensing from a conventional pull and tear tape dispenser. The tape product includes a paper layer and a water-impermeable plastic film layer having a first corona-discharge treated surface. The first corona-discharge treated surface is adhesively laminated to the paper layer to form a paper-plastic film laminate having first and second opposed outer surfaces. The tape product additionally includes a layer of a pressure-sensitive adhesive coating on one of the first and second outer surfaces. The pressure-sensitive adhesive coating is exposed for use in adhering the paper-plastic film laminate to the various items. The plastic film layer has a sufficient strength to allow the film to be stripped in one piece from an item to which the laminate is adhered.
The tape product of the invention may optionally further include a layer of a release agent located upon a remaining uncoated outer surface. Preferred release agents for use with the invention include the silicones.
In one embodiment of the invention the paper layer has a thickness of from about 3 to about 6 mils, while the plastic film layer has a thickness of from about 1 to about 3 mils.
In a further embodiment the plastic film component of the pressure sensitive sealing tape product is an oriented film comprising a polymer selected from the group consisting of polypropylene, polyethylene and polyester. In the subject embodiment, the paper layer preferably comprises Kraft paper.
In another embodiment, the first corona discharge treated surface of the plastic film layer may be adhesively laminated to the paper layer by a water-based adhesive. The water-based adhesive may include, for example, an acrylic copolymer composition or a polyvinyl acetate copolymer. The pressure sensitive adhesive preferred for use with the invention may be selected from among rubbers, vinyl rubbers, polyvinylethers, polyvinylbutyrals, polyisobutylenes and acrylics. The pressure sensitive adhesive may be applied to either the paper side or the film side of the laminate. Additionally, if desired, an outer surface of the plastic film layer may be metallized.
It is desirable, in forming the pressure sensitive sealing tape of the present invention, to utilize an adhesive for laminating the first corona discharge treated surface to the paper layer which will produce a stronger bond than that produced by the pressure sensitive adhesive to allow the paper-plastic film laminate to be stripped off of an item to which it is adhered in one piece.
In another embodiment, the pressure sensitive sealing tape product of the invention comprises a paper layer having a first surface and a second opposed surface; an oriented, water impermeable plastic film having a first corona discharge treated surface and a second, opposed surface, wherein the first corona discharge treated surface is adhesively laminated to the first surface of the paper layer to form a paper-plastic film laminate; an exposed layer of a pressure-sensitive adhesive coating upon the second surface of the paper layer; and a layer of a release agent located upon the second, opposed surface of the plastic film. The plastic layer incorporated in the above-described embodiment should have sufficient strength to allow the film to be stripped in one piece from an item to which the laminate is adhered.
In a further embodiment the invention is directed to a pressure-sensitive sealing tape product for adhering to various items in applications involving taping and sealing, wherein the tape product possesses sufficient body to permit dispensing it from a conventional pull and tear tape dispenser. The tape product comprises a first paper layer; a water impermeable plastic film layer having first and second corona discharge treated surfaces, wherein the first corona discharge treated surface is adhesively laminated to the paper layer to form a paper-plastic film laminate having first and second opposed outer surfaces; and, an exposed layer of a pressure-sensitive adhesive coating on one of the outer surfaces of the laminate. The plastic film layer has a sufficient strength to allow the film to be stripped in one piece from an item to which the laminate is adhered.
If desired the pressure sensitive sealing tape product may further com
Bloch Gerald
Bloch Gilbert
Finestone Arnold B.
Boyer Charles
Gupta Yogendra
Winston & Strawn
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