Adhesive tape and apparatus for making same

Abstract

The invention relates to a device for producing an adhesive tape (2), comprising a supply unit (5) for supplying a strip-type textile carrier (3) of the adhesive tape (2), and a coating unit (6) for applying an at least lamellar adhesive coating (4) to at least one side of the carrier (3). The invention also relates to an ultrasound unit (9 and 10) and/or a laser unit for producing perforations and/or cut edges in the carrier (3).

Claims

1. An apparatus for making an adhesive tape, the apparatus comprising: a supply for feeding a ribbon-shaped textile substrate strip of thermoplastic fibers in a longitudinal feed direction along a path; a coater downstream of the supply along the path for applying a strip-shaped adhesive coating to at least one face of the substrate strip; an ultrasound or laser device provided between the supply and the coater and movable in three dimensions, transversely and longitudinally of the longitudinal feed direction and also toward and away from the moving web for forming longitudinal and transversely extending rows of perforations and/or cut edges in the moving substrate strip; and a cutter downstream of the coater for cutting the perforated/cut and coated strip into a plurality of longitudinally extending tapes.

2. The apparatus defined in claim 1, wherein the ultrasound device is provided with a sonic blade and an oppositely situated anvil between which the substrate strip is passed, the blade and the anvil being movable transversely of the moving strip during movement of the strip past the ultrasound device.

3. The apparatus defined in claim 2, wherein at least the anvil oscillates above 20 kHz.

4. The apparatus defined in claim 1, wherein the ultrasound or laser device is an edge welder.

5. The apparatus defined in claim 1, wherein the ultrasound or laser device is a combined welder/cutter.

Description

BRIEF DESCRIPTION OF THE INVENTION

(1) The invention is explained in further detail below with reference to a schematic drawing showing only one embodiment:

(2) FIG. 1 shows an apparatus according to the invention for making an adhesive tape,

(3) FIG. 2 is a detailed view of the ultrasound device, and

(4) FIG. 3 is a top view of the adhesive tape manufactured with the aid of the apparatus according to FIGS. 1 and 2.

SPECIFIC DESCRIPTION OF THE INVENTION

(5) FIGS. 1 and 2 show an apparatus that produces at an outlet end one or more adhesive tapes 2 from a substrate strip 1. The adhesive tape 2 is illustrated in principle in a top view according to FIG. 3. The substrate strip 1 is a laminar textile web and can be cut in its longitudinal direction into a plurality of the adhesive tapes 2, as will be explained in detail below. In order to define the individual adhesive tapes 2 for this purpose, the substrate strip 1 is longitudinally subdivided into substrate pieces 3.

(6) The adhesive tape 2 has in its inherent structure the above-mentioned substrate piece 3 and at least one adhesive strip 4 or strip-shaped adhesive coating 4 that is applied to the substrate piece 3. The adhesive coating 4 is applied to at least one face of the substrate piece 3. In the context of the embodiment according to FIG. 3, the adhesive strip 4 is provided only on one top face of the substrate piece 3 as the coated face. As a matter of principle, an additional an adhesive strip 4 can also be applied to the bottom side or to both sides. It lies within the scope of the invention to work with an adhesive strip 4 that covers only a portion, for example up to 50% of the coated face of the substrate piece 3. The coated face of the substrate piece 3 can also be provided with the adhesive strip 4 over its entire surface.

(7) The substrate piece 3 and, consequently, the substrate strip 1 defining the substrate piece 3, is a ribbon-shaped textile substrate piece 3. The ribbon-shaped textile substrate piece 3 can be made of a woven or nonwoven fabric. Plastic fibers are preponderantly used as the material for the substrate piece 3. In principle, a substrate piece 3 that is made of a laminate consisting of a woven fabric and a nonwoven fabric can also be used. Here, the weight per unit area of the substrate piece 3 lies in the range between 100 g/m.sup.2 to 300 g/m.sup.2. Even greater weights per unit area are also conceivable in principle.

(8) The adhesive strip 4 applied to the coated face of the substrate piece 3 with the aid of a so-called acrylate-based hot melt adhesive or melt adhesive composition. A coater 6, which will be described in further detail below, is provided for this purpose. The coater 6 may be provided with a mask or an appropriately shaped nozzle in order to define the adhesive strip 4 on the coated face of the substrate piece 3 shown in FIG. 3.

(9) The substrate strip 1 is fed from a supply 5 with the aid of the apparatus according to FIG. 1. In the illustrated embodiment of FIG. 1, the substrate strip 1 is first perforated in the by an ultrasound device 9, 10, then coated and subsequently cut into the individual adhesive tapes 2. The perforation with the aid of the ultrasound device 9, 10 can also occur after cutting. The two basic positions of the ultrasound device 9, 10 are shown in FIG. 1. Generally, the procedure is such that the ultrasound device 9, 10 is arranged upstream of the coater 6 or nozzle in order to form the perforations into the substrate strip 1 in the feed direction R of the substrate strip 1 indicated by an arrow in FIG. 1. That is why the ultrasound device 9, 10 is shown with solid lines in this position, whereas the other, second optional position of the ultrasound device 9, 10 after the cutting of the substrate strip 1 into the adhesive tapes 2 is shown with dot-dash lines. In this case, the ultrasound device 9, 10 is located downstream of the coater 6 in the feed direction R of the substrate piece 3.

(10) In general, however, it is also possible for the perforation and coating on the one hand and the cutting of the perforated and coated substrate strip 1 on the other hand to take place in separate apparatuses. Even having a perforation that is first made on the one hand and the subsequent coating and cutting into the adhesive tapes 2 on the other hand be performed in separate apparatuses is also expressly covered by the invention.

(11) The supply 5 is generally a supply roll on which the substrate strip 1 is wound. The substrate strip 1 is configured as a flat textile web that is or can be embodied here as a woven web, nonwoven web, etc., or also as a combined laminate of woven/nonwoven fabric. Moreover, it lies within the scope of the invention to provide the substrate strip 1 with an additional coating, a paint coating, a film coating, etc., in addition to the adhesive strip 4. That is not shown in detail, however.

(12) The substrate strip 1 has a total width that is or can be a multiple of the total width A of the adhesive tape 2 shown in FIG. 3. In fact, the substrate strip 1 can have a width of 3A to 20A, with A being the width of the adhesive tape 2.

(13) Starting from the supply 5, the substrate strip 1 is first fed to the ultrasound device 8, 9. Here, perforations are formed in the substrate strip 1 with the aid of the ultrasound device 8, 9. Here, and without it constituting a restriction, these perforations are transverse perforations. These transverse perforations can be seen in FIG. 3 in the top view of the adhesive tape 2 through transverse perforation lines 11. With the aid of these transverse perforation lines 11, more particularly the transverse perforations, it is possible to configure an adhesive tape 2 to be manually tearable that would not otherwise be manually tearable, which means in the context of the invention that total transverse tearing forces of no more than 10 N/cm are required in order to tear the adhesive tape 2 transversely.

(14) With the aid of the ultrasound device 9, 10, these transverse perforations or the corresponding transverse perforation lines 11 are formed into the substrate piece 3 or substrate strip 1 in regular intervals transverse to the feed direction R of the substrate piece 3 or substrate strip 1. To achieve this, it is possible to use a plurality of ultrasound devices 9, 10 that are arranged transverse to the substrate piece 3 or substrate strip 1. It is also possible, however, to use one (single) ultrasound device 9, 10 that moves transversely to the feed direction R of the substrate piece 3 or substrate strip 1 in order to form the transverse perforations. In other words, the ultrasound device 9, 10 is designed to be displaceable relative to the substrate piece 3, as the corresponding arrows indicate in FIG. 1. Not only is displacement perpendicular to the substrate piece 3 possible, but rather also transverse to the substrate, which results in three-dimensional displacement overall. The ultrasound device 9, 10 is composed of a blade or sonic blade 9 and an oppositely situated anvil 10. The anvil 10 is usually a sonic anvil, which means that the anvil 10 is oscillated. The substrate piece 3 or substrate strip 1 is passed between the sonic blade 9 and the anvil or sonic anvil 10.

(15) Since the sonic blade 9 and/or the anvil or sonic anvil 10 is typically excited to oscillations having a frequency above 20 kHz, corresponding frequencies are not audible on the one hand and, on the other hand, are set up such that minimal surface friction occurs between the sonic blade 9 and the substrate strip 1 or substrate piece 3. As a result of this minimal surface friction, the substrate strip 1 is cut open or cut into. A perforation cut is made. Movement of the ultrasound device 9, 10 transverse to the feed direction R forms a plurality of these perforation cuts in regular intervals in the substrate piece 3 or substrate strip 1, whereby the transverse perforations shown in FIG. 3 or a plurality of these transverse perforation lines 11 are created.

(16) By virtue of the fact that the sonic blade 9 performs the above-described oscillations in the ultrasonic range, the substrate strip 1 or substrate piece 3 is heated in the contact region between the sonic blade 9 and the textile material in question. Since the substrate strip 1 and hence the substrate piece 3 is constructed preponderantly from plastic fibers, the plastic fibers in question are melted at least in the area of the perforation edges surrounding the perforations or perforation cuts at the temperatures produced as a result of the surface friction. The invention proceeds here from the realization that the acoustic energy that is available during the formation of the perforations or in the individual perforation cuts as a result of the oscillation of the sonic blade 9 is sufficient to heat the perforation edge in the region of the individual perforation cuts and thus provide for the desired welding at the perforation edge.

(17) In the same way, the ultrasound device 9, 10 can also be used alternatively or in addition in order to produce the individual adhesive tapes 2 by cutting the coated substrate strip 1 longitudinally. In this case, the ultrasound device 9, 10 replaces a cutting apparatus 7, 8 shown in the context of FIG. 1 which is composed here of a rotating blade 7 and an associated oppositely situated anvil 8. Generally, a plurality of these rotating blades 7 and associated anvils 8 are provided, namely at a regular spacing from one another that corresponds to the width A of the adhesive tape 2 after the cut in the embodiment. If the ultrasound device 9, 10 is used here, longitudinal cuts are produced with it, and the cut edges on the associated longitudinal edge 3A, 3B of the adhesive tape 2 are heated by the described surface friction. As was already explained relative to the perforation cuts and the transverse perforation lines 11 that are produced, it also happens in like manner that, during a cut with the aid of the ultrasound device 9, 10, the cut edges in question are welded at the longitudinal edges 3A, 3B.

(18) As already explained above, the sonic blade 9 of the ultrasound device 9, 10 oscillates ultrasonically. Alternatively or in addition, the oppositely situated anvil or sound anvil 10 can be excited to oscillate ultrasonic oscillations. In this case, the sonic anvil 10 in question is also caused to perform ultrasonic oscillations beyond the audible limit. It is then possible to even dispense with the vibrating of the sonic blade 9. As will readily be understood, the invention also includes variants in which both the sonic blade 9 and the sonic anvil 10 each oscillate ultrasonically.

(19) Since the substrate strip 1 is constructed preponderantly from plastic fibers in that the plastic fibers in the substrate strip 1 amount to greater than 50% by weight (wt %), the heating produced with the aid of the ultrasound device 9, 10 at the cut edge or perforation edge ensures that individual plastic fibers melt at least partially. The substrate piece 3 is thus sealed in the region of the cut edge at the longitudinal edges 3A and 3B of the substrate piece 3 and at the perforation edge. The cut edge or perforation edge is thus prevented from fraying. This facilitates the subsequent processing and manufacture of the adhesive tapes 2.

(20) Downstream of the ultrasound device 9, 10 and the formation of the transverse perforations, the perforated substrate strip 1 is guided over one or more deflection rollers until it reaches the above-mentioned coater 6 and passes through it. Here, the coater 6 is merely a nozzle that applies the one adhesive strip 4 depicted in FIG. 3 to the coated face of the substrate piece 3 or substrate strip 1. It will readily be understood that more than one nozzle can also be used in the coater 6.

(21) FIG. 1 shows that the coater 6 or nozzle extends transversely of the feed direction R and the longitudinal extension of the substrate strip 1. Moreover, the substrate strip 1 is guided vertically or nearly vertically in the vicinity of the coater 6 or nozzle. This is obviously only for the sake of example and not mandatory. The inclined or vertical orientation of the substrate strip 1 in the vicinity of the coater 6 enables the particularly exact application of the adhesive strip 4. After all, the invention also make use here of gravitational forces of the melt adhesive composition as it usually leaves the nozzle. That is, the melt adhesive composition in question can be applied onto the coated face of the substrate piece 3 or, in this case, onto the substrate strip 1 with an exactly defined edge and ultimately without lateral raggedness.

(22) In any case, the substrate strip 1 passes through the coater 6 or nozzle, so that the adhesive emerging from the nozzle forms the adhesive strip 4 shown in FIG. 3 or several of these adhesive strips 4 on the substrate strip 1.

(23) After the adhesive strip 4 shown in FIG. 3 has been applied to the coated face of the substrate piece 3 or substrate strip 1 for each adhesive tape 2 of width A to be produced subsequently, the substrate strip 1 passes through the above-mentioned cutting apparatus 7, 8 with the plurality of adhesive strips 4 corresponding to the number of adhesive strips 2 to be produced subsequently. Here, the cutting apparatus 7, 8 is a cutter bar with a plurality of rotating blades 7 in its longitudinal extension and transverse to the substrate strip 1 that is passing through. The rotating blades 7 are spaced apart by the distance A, which corresponds to the width A of the adhesive tapes 2 to be subsequently produced therefrom.

(24) With the aid of the rotating blades 7, the substrate strip 1 is cut in the longitudinal direction and in the feed direction R into the individual adhesive tapes 2. An anvil 8 that is situated opposite the center substrate strip 1 is associated for this purpose with each rotating blade 7. The anvil 8 may rotate contrary to the blade 7, as corresponding arrows indicate in FIG. 1. The rotating blade 7 can thus pass through the substrate strip 1, thus producing the cut edges at the two longitudinal edges 3A, 3B, which cut edges can fray when the blades 7 and anvils 8 are used. If, however, the ultrasound device 9, 10 is used as shown instead of the cutting apparatus 7, 8, then the longitudinal edges 3A, 3B of the ribbon-shaped substrate piece 3 are also welded. In other words, the ultrasound device 9, 10 used in place of the cutting apparatus 7, 8 is a combined welder/separator 7, 8.

(25) After the substrate strip 1 has been subdivided longitudinally into the individual adhesive tapes 2 in this way, the individual adhesive tapes 2 can be wrapped onto a roll 12. This may be a so-called turret winder that is constructed and works in a manner comparable to the description given in the applicant's WO 2013/024150.

(26) In any case, the substrate strip 1 is manufactured at high speed and provided with smooth and clean cuts in the longitudinal direction and transverse perforation lines 11. The cut edges and perforation edges are simultaneously welded and sealed or melted by ultrasound. This ensures that the cut edges or perforation edges do not fray. In adaptation to the application, cutting can be performed vertically, horizontally, or continuously with appropriate sonotrodes for the sonic blade 9 used. The same advantages and effects are observed if a laser device is used in place of the ultrasound device 9, 10. That is not shown, however.

(27) Moreover, the invention relates to a method of making an adhesive tape 2, particularly a wrapping tape for wrapping an elongated object, preferably a wrapping tape for wrapping cable sets in automobiles, according to which the ribbon-shaped textile substrate piece 3 is fed from a supply 5 and, with the aid of a coater 6, subsequently provided with an at least strip-shaped adhesive coating 4 on at least one face of the substrate piece 3, and according to which, in accordance with the invention, the ultrasound device 7, 8 and/or the laser device provides for the creation of perforations and/or cut edges in the substrate piece 3.