GEOMETRICALLY DEFINED PRESSURE-SENSITIVE ADHESIVE FILM

Abstract

The present invention relates to a geometrically defined pressure-sensitive adhesive film which is produced in a continuous roll-to-roll process by means of a polyjet modeling method, wherein, due to this printing process, adhesive films no longer have to be subsequently stamped, which contributes to avoiding waste and thus conserving resources.

Claims

1.-16. (canceled)

17. An adhesive tape having at least one pressure-sensitive adhesive film, which is capable of connecting two joining partners to one another only by applying pressure, wherein the adhesive tape is designed either as a transfer adhesive tape, wherein the adhesive tape is applied to a release liner or between two release liners and the release liners are provided to be pulled off upon an application of the transfer adhesive tape to expose adhesive surfaces of the adhesive film, or is designed as a rolled adhesive tape having a single double-sided repellent liner characterized in that the adhesive film is produced by means of a polyjet modeling method, wherein the adhesive is applied by means of piezoelectric actuators in the nozzles at frequencies between 10 kHz and 100 kHz to the release liner or the double-sided repellent liner and no subsequent shaping process takes place.

18. The adhesive tape as claimed in claim 1, characterized in that the adhesive film has geometrically defined forms in both a two-dimensional and three-dimensional aspect.

19. The adhesive tape as claimed in claim 1, characterized in that the adhesive film has UV acrylates, hot melts, and/or solvent-based and water-based acrylates and is printed in the viscosity range from 2 mPas to 100 mPas.

20. The adhesive tape as claimed in claim 1, characterized in that the applied drop volume varies between 2 and 200 pl.

21. The adhesive tape as claimed in claim 1, characterized in that the adhesive film consists of multiple different adhesive film layers, which are both variations of UV acrylates, hot melts, and solvent-based and water-based acrylates and also variations of the four different chemistries.

22. The adhesive tape as claimed in claim 1, characterized in that the adhesive film has a thickness of between 1 μm and 3000 μm.

23. The adhesive tape as claimed in claim 1, characterized by a functionalization to create a thermal or electrical conductivity.

24. The adhesive tape as claimed in claim 1, characterized by a functionalization to create active ingredient patches by means of drugs or medical active ingredients.

25. The adhesive tape as claimed in claim 1, characterized by a functionalization by means of herbicides and biocides.

26. The adhesive tape as claimed in claim 1, characterized by a coloration of the adhesive films and/or a display of color effects of the adhesive film.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0038] Preferred further embodiments of the invention are explained in more detail by the following description of the figures. In the figures:

[0039] FIG. 1 shows a complex geometrically defined pressure-sensitive adhesive film according to one embodiment; and

[0040] FIG. 2 shows a schematic illustration of a roll-to-roll method.

DETAILED DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS

[0041] Preferred exemplary embodiments are described hereinafter on the basis of the figures. Identical, similar, or identically-acting elements are provided in the different figures with identical reference signs, and a repeated description of these elements is partially omitted to avoid redundancies.

[0042] Production of the Geometrically Defined Pressure-Sensitive Adhesive Layers

[0043] To produce the respective geometrically defined pressure-sensitive adhesive layers, the respective contact adhesive compounds are provided in storage containers. The printing viscosity is between 2 mPas and 100 mPas, preferably between 5 mPas and 20 mPas.

[0044] Subsequently, the adhesive is applied by means of piezoactuators in the nozzles at frequencies between 10 kHz and 100 kHz, preferably between 12 kHz and 60 kHz, to the liner. The applied drop volume can vary between 2 and 200 pl (picoliters), typically between 10 and 100 pl.

[0045] To produce the adhesive compound layers, that is to say the carrier-free contact adhesive tapes, the various adhesive compounds (UV acrylate, solvent-based or water-based system) are applied to a conventional liner (siliconized polyester film) by means of a printhead in the inkjet method (layer by layer) and irradiated or dried immediately thereafter either using a UV lamp having UVA, UVB, or UVC. The thickness of the transfer film is 300±20 μm thereafter. The adhesive films thus produced are each laminated immediately after the polymerization or drying using a second liner (siliconized polyester film having lower release force than the first liner) on the still open adhesive side.

[0046] Exemplary Production of the Geometrically Defined Pressure-Sensitive Adhesive Film.

[0047] In the present example, a standard UV acrylate from Lohmann was used, which consists of 2-ethylhexylacrylate, acrylic acid, and a radical photo initiator.

[0048] This was printed using a Fujifilm Dimatix Q-class printhead in a width of 64 mm at a drop volume of 80 pl. The shaping was selected similarly to the test guidelines described hereinafter and thus in the form of test strips having a thickness of approximately 300 μm (example K1).

[0049] At the same time, a more complex geometry similar to FIG. 1 was printed in order to study the limits of the method.

[0050] The geometrically defined pressure-sensitive adhesive film was produced in a continuous roll-to-roll process (FIG. 2). The reference signs have the following meaning:

[0051] In parallel thereto, an adhesive film having the identical formula was coated on the identical liner in a thickness of 500 μm (R1) by means of a coating facility, in order to be able to judge the mechanical performance of the adhesive film produced in the polyjet modeling method by comparison.

[0052] Results of the Contact Adhesive Compounds with Respect to Thickness, Adhesion, and Tensile Shear Strength

[0053] Adhesion:

[0054] The adhesion is determined on steel based on DIN EN 1464:2010 at 23° C.±2° C. and 50%±5% relative ambient humidity at a pull-off speed of 300 mm/minute and a pull-off angle of 110° in the roll peeling test. An etched film made of PET having a thickness of 50 μm is used as the reinforcing film. The adhesive bonding of a 25 mm wide measurement strip on the steel substrate is performed here by means of a contact roller of 5 kg at a temperature of 23° C.±2° C. The adhesive film is pulled off 10 minutes (initial) or 24 h (24 h) after the application at 300 mm/minute. The measured value (in N/mm) results as the mean value from five individual measurements including standard deviation.

[0055] Thickness:

[0056] As the characteristic variable for the thickness of the adhesive film, thickness measurements are performed based on DIN EN 1942:2008 at 23° C.±2° C. and 50%±5% relative ambient humidity. The results are specified in mm. The mean value from five measurements is specified in each case.

[0057] Tensile Shear Strength:

[0058] As the characteristic variable for the strength of the adhesive bonds on steel, tensile shear tests are carried out according to DIN EN 1465 at 23° C.±2° C. and 50%±5% relative ambient humidity and a test speed of 10 mm/minute. Steels made of alloy 1.4301 are used as the test substrates, which are cleaned using acetone, on the one hand, and are subjected to a mechanical surface treatment by means of cross grinding, on the other hand. The samples are produced by means of a contact roller of 5 kg at a temperature of 23° C.±2° C. and tested 24 h after the application. The results are specified in MPa (N/mm.sup.2). The mean value from five measurements including standard deviation and fracture pattern assessment is specified in each case.

TABLE-US-00001 Example: K1 R1 Thickness [mm] 0.30 ± 0.02 0.50 ± 0.05 Adhesion (initial) [N/mm] 1.40 ± 0.10 (AF/CF) 1.32 ± 0.10 (AF/CF) Adhesion (24 h) [N/mm] 1.69 ± 0.05 (AF/CF) 1.65 ± 0.04 (AF/CF) Tensile shear strength [MPa] 0.46 ± 0.05 (CF) 0.22 ± 0.05 (CF) Legend: AF: adhesion fracture; CF: cohesion fracture

[0059] The adhesive films K1 and R1 have an identical chemical composition. Only the production method is varied. R1 is thus coated by means of standard coating methods in the 2-roller application in a width of 450 mm and band polymerized. In contrast thereto, K1 is applied by means of a polyjet modeling method in the width to be tested and also band polymerized. The two adhesive films have different thicknesses due to the type of production, however.

[0060] The adhesive compounds K1 and R1 have equal adhesion both initially and also after 24 hours in the scope of the standard deviation.

[0061] With respect to the tensile shear strength, however, K1 has a higher tensile shear strength than R1, which is to be attributed according to experience to the lower adhesive layer thickness, however. The tensile shear strengths would thus also be equal in the scope of the standard deviation at identical adhesive layer thickness.

[0062] Overall, it can thus be stated that the geometrically defined pressure-sensitive adhesive layer which was produced by means of a polyjet modeling method has the same adhesive-technology properties as a conventional coated adhesive film.

[0063] If applicable, all individual features which are represented in the exemplary embodiments can be combined and/or exchange with one another without leaving the scope of the invention.

LIST OF REFERENCE SIGNS

[0064] 1 unroller [0065] 2 printing head having the nozzles [0066] 3 irradiation/drawing [0067] 4 roller [0068] 5 adhesive tape transport liner