PHYSICAL PRETREATMENT FOR FILAMENT FIXATION

Abstract

Method for producing an adhesive tape including the steps of providing an adhesive layer to at least one side of a liner or a carrier film and treating at least one filament and/or the adhesive layer with a plasma, and introducing the at least one filament into the adhesive layer.

Claims

1. Method for producing an adhesive tape, comprising the steps of providing an adhesive layer on at least one side of a liner or a carrier film, and treating at least one filament and/or the adhesive layer with a plasma, and introducing the at least one filament into the adhesive layer.

2. Method according to claim 1, wherein a first adhesive layer is applied to the liner or the carrier film, and a surface of the at least one filament is treated with plasma and applied to the first adhesive layer, and optionally a second adhesive layer is applied over the at least one plasma-treated filament and the first adhesive layer.

3. Method according to claim 1, wherein a first adhesive layer is applied to the liner or the carrier film, a surface of the first adhesive layer is treated with plasma and the at least one filament is applied to the first plasma-treated surface of the first adhesive layer, and a second adhesive layer is applied over the at least one filament and the plasma-treated surface of the first adhesive layer.

4. Method according to claim 1, wherein air, carbon dioxide, inert gases, or nitrogen or mixtures thereof is/are used as the process gas for the plasma treatment.

5. Method according to claim 4, wherein hydrogen, alkanes, alkenes, alkynes, silanes, silicon-organic monomers, acrylate monomers, water, alcohols, peroxides or organic acids are added to the process gas in the form of vapor or aerosols.

6. Method according to claim 1, wherein the at least one filament is selected from the group consisting of PET fibers, carbon fibers, Kevlar fibers or glass fibers.

7. Method according to claim 1, wherein the at least one filament is created from a bundle of single filaments which are bonded with a sizing agent.

8. Method according to claim 7, wherein glass fibers are bundled together with a sizing agent to form a filament, and filaments with different sizing agents are used to produce the adhesive tape, and all filaments with different sizing agents are treated with plasma.

9. Method according to claim 1, wherein the entire extent of the at least one filament is treated with plasma.

10. Adhesive tape having an adhesive layer and at least one filament introduced in the adhesive layer, wherein the adhesive layer and/or one surface of the at least one filament has been treated with a plasma.

11. Adhesive tape according to claim 10, wherein the at least one filament originates from the group consisting of PET fibers, carbon fibers, Kevlar fibers or glass fibers.

12. Adhesive tape according to claim 10, wherein the at least one filament consists of glass fiber single filaments bundled together by a sizing agent.

13. Adhesive tape according to claim 10, wherein the at least one filament has been treated with plasma.

14. Adhesive tape according to claim 10, wherein the adhesive layer has been applied to a liner or a carrier film.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0093] In the figures

[0094] FIG. 1 is a schematic representation of a static shear test,

[0095] FIG. 2 shows an exemplary structure of an adhesive tape according to the invention,

[0096] FIG. 3 is a graphical representation of the time to detachment of adhesive tape strips from films.

[0097] One possible way to test the fixation of a filament in an adhesive layer is to determine the shear resistance of the adhesive bond on a readily bondable base. In this case, an etched PET film was used as the base. A conventional static shear test, the setup for which is represented diagrammatically in FIG. 1 is used as the measuring method to determine the shear resistance. The test is carried out as follows. The etched PET film is affixed to the entire surface of a 22550 mm test plate of non-ground steel. An adhesive tape strip with dimensions 4013 mm is adhesively bonded to the etched PET film over an area of 2013 mm; the adhesive tape strip is a film carrier 1 on which a filament layer consisting of glass fibre filaments 21 and coated with a pressure-sensitive adhesive 2 has been positioned; in this case, acrylate adhesive was used as the pressure-sensitive adhesive. FIG. 2 shows the adhesive tape. A weight is fastened to the protruding end of the adhesive tape strip. Pressure of 10 Newton per cm.sup.2 is applied to an adhesion area for one minute. The sample together with the steel plate is fastened to a sample holder and the weight is attached to the protruding end of the adhesive tape strip. The time until the adhesive tape strip shears off was measured; in this case, the failure profile indicates the failure of the pressure-sensitive adhesive on the filament layer, the pressure-sensitive adhesive is thus left on the etched PET film.

[0098] For the sake of simplicity, the adhesive on the strip is only shown in the adhesion area.

[0099] Experiments were conducted with two different glass fibre filaments from different manufacturers. The two glass fibre filaments differed from one another only in the sizing agent that was used. The results are represented in the form of a graph:

[0100] The time to detachment is shown in FIG. 3; in the case of the first filament, the time until the adhesive tape strip sheared off from the PET film was about 4,500 minutes, in the second experiment, this time was only about 1,000 minutes.

[0101] In addition, the shear resistances of the same filaments after a corona treatment before the filaments were coated with adhesive were measured.

[0102] It should first be noted that the filaments in the untreated state had different shear resistances. Thus it may be assumed that the filaments also have different wettability properties. With the corona treatment as a particular form of plasma treatment, the shear resistance of both filaments is significantly increased and rendered more uniform; it is evident that the plasma treatment results in comparable wettability properties after the plasma treatment, even though the wettability properties of the untreated filaments were different. The physical surface treatment of the filaments with plasma enables filaments that have undergone different pretreatments to be incorporated in the adhesive assembly with the same effect.

LIST OF REFERENCE SIGNS

[0103] 1 Carrier film [0104] 2 Adhesive layer [0105] 21 Filaments