MULTILAYER ADHESIVE BONDING ELEMENT

Abstract

Method for bonding by wrapping a medium which expands transversely to a winding with an adhesive tape, in which: an adhesive tape is unrolled from an adhesive tape roll, the unrolled adhesive tape is provided on one side of a carrier film (1) with an adhesive cement layer (2) and on an opposite side partially with a separating agent layer (3), wherein the area covered by the separating agent layer (3) takes up not more than 50% of the total area of the carrier reverse side, wherein at least the surface of the side of the carrier film (1) which is furnished with a separating agent layer (3) is etched, the adhesive tape is wound around the medium which expands transversely to a winding, so that at least a portion of the adhesive tape is bonded to a lower winding ply by the adhesive cement layer (2).

Claims

1. Method for bonding by wrapping a medium which expands transversely to a winding with an adhesive tape, in which: an adhesive tape is unrolled from an adhesive tape roll, the unrolled adhesive tape is provided on one side of a carrier film (1) with an adhesive cement layer (2) and on an opposite side partially with a separating agent layer (3), wherein the area covered by the separating agent layer (3) takes up not more than 50% of the total area of the carrier reverse side, wherein at least the surface of the side of the carrier film (1) which is furnished with a separating agent layer (3) is etched, the adhesive tape is wound around the medium which expands transversely to a winding, so that at least a portion of the adhesive tape is bonded to the adhesive cement layer (2) on a lower winding ply.

2. Method according to claim 1, wherein the side which is opposite the side furnished with the adhesive cement layer (2) is not furnished with a separating agent layer (3) and/or other layer.

3. Method according to claim 1, wherein the adhesive tape is wound around the medium in several winding plies which are bonded one on top of the other.

4. Method according to claim 1, wherein trichloroacetic acid (Cl.sub.3CCOOH) or trichloroacetic acid in combination with inert crystalline compounds are used to etch the carrier film (1).

5. Method according to claim 1, wherein an adhesive cement of the adhesive cement layer (2) is selected from the group consisting of adhesive cements based on natural or synthetic rubber.

6. Device with a medium whose size is variable transversely to the winding and an adhesive tape that is wound onto itself around the medium transversely to the winding with a carrier film (1), on one side of which an adhesive cement layer (2) is applied, and on the other side of which a plasma-treated separating agent layer (3) is applied.

7. Device according to claim 6, wherein the adhesive tape is bonded in several winding plies one on top of the other.

8. Device according to claim 6, wherein the adhesive tape includes at least one filament which increases the tensile strength thereof.

9. Device according to claim 6, wherein a plurality of filaments is provided in the adhesive tape.

10. Device according to claim 6, wherein a separating agent in the separating agent layer (3) originates from the group consisting of surfactant release systems based on long-chain alkyl groups such as stearyl sulfosuccinates or stearyl sulfosuccinamates; polymers selected from the group consisting of polyvinylstearyl carbamates, polyethylene imine stearyl carbamides, chromium complexes of C14-C28 fatty acids and stearyl copolymers or based on acrylic polymers with perfluorinated alkyl groups; silicones or fluorosilicone compounds.

11. Device according to claim 6, wherein an adhesive cement in the adhesive cement layer (2) originates from the group consisting of adhesive cements based on natural or synthetic rubber.

12. Applicator with an adhesive tape roll and a device for unwinding an adhesive tape from the adhesive tape roll, wherein the adhesive tape unwound from the adhesive tape roll is furnished on one side of a carrier film (1) with an adhesive cement layer (2) and on an opposite side with a separating agent layer (3), and with a plasma nozzle, which is directed at the separating agent layer (3) of the unwound adhesive tape.

13. Applicator according to claim 12, comprising a cutting device for the adhesive tape.

14. Applicator according to claim 12, comprising a suction device for reaction byproducts created during a plasma treatment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0068] FIG. 1 shows a schematic representation of a static shear test,

[0069] FIG. 2 shows an exemplary structure of an adhesive tape according to the invention,

[0070] FIG. 3 illustrates the shear resistance increase with the use of an etched film as carrier.

[0071] The invention relates to a method for winding multiple times around media that expand transversely to the winding. An example of such a use is the manufacture of high-voltage batteries, in which the adhesive tape is bonded to itself in multiple plies. A force is exerted on the wound adhesive tape by the preloading created during the act of winding itself, but also by expansion processes while the batteries are charging and discharging. In order to be able to sustain in an extreme manner the tensile forces acting on the adhesive tape during the expansion of the battery, the adhesive tape may be reinforced with one or more filaments extending lengthwise.

[0072] The adhesive tape according to the invention includes an etched carrier film 1 and an adhesive cement layer 2 on one side of carrier film 1.

[0073] One possible way to test the bonding strength of the adhesive cement that has been applied to one side of the carrier film on the other side is to determine the shear strength of the adhesion on the other side. The method used to determine shear strength is a dynamic shear test as represented in FIG. 1. The test is carried out as follows. A strip of adhesive tape measuring 4025 mm is stuck to the reverse side of a strip of adhesive tape measuring 4025 mm over an area of 2525 mm; the adhesion area is pressed with 100 N/cm.sup.2 for one minute. The adhesive tape assemblage is attached to a tensile test machine by the protruding strip of adhesive tape; the sample is pulled apart at a speed of 50 mm per minute and the force relative to the adhesion area (N/cm.sup.2) at which the strip of adhesive tape has been sheared off is measured. The tensile forces are indicated by arrows.

[0074] For the sake of simplicity, the adhesive cement on the upper strip of adhesive tape is not shown at all. Moreover, the adhesive cement is only shown in the adhesion area on the second strip.

[0075] The carrier film 1 in the Comparative Examples 1 and 2 is a siliconized PET film, and in Example 3 an etched PET film. An acrylate adhesive cement is used as a pressure-sensitive adhesive. The following graph shows that the shear resistance with respect to the coating of the adhesive tape reverse side with silicone is increased by a plasma treatment. To this end, a physical surface treatment in the form of a plasma treatment immediately before the adhesive tape is applied has the effect of optimizing the adhesion of the reverse side of the carrier film which is furnished with a separating agent. With the use of an etched film as carrier, a marked and unexpectedly high increase, in this case virtually a doubling of the shear resistance, can again be seen (see FIG. 3).

[0076] Compared with the known standard adhesive tapes which have not undergone plasma treatment of the reverse side, the following advantages may be mentioned: [0077] Reliable attachment in the case of multilayer bonding. Inter alia, this can prevent the last layer of the bonding arrangement from positioning itself. [0078] Process steps such as a plasma treatment for improving the bondability of the reverse side are unnecessary.

LIST OF REFERENCE SIGNS

[0079] Carrier film [0080] Adhesive cement layer