Adhesive tape and method for covering elongate articles, in particular leads

Abstract

The invention relates to an adhesive tape for covering elongate articles, such as in particular leads or cable sets, comprising a tape-like carrier which is provided on at least one side with a curable adhesive compound, in which the tape-like carrier is permeable to UV radiation and the curable adhesive compound is coloured, wherein it has an L* value according to CIELAB of < 40, has improved curability and can be sufficiently activated within the cycle times specified by the automotive industry in order to effect curing of the curable adhesive compound.

Description

[0001]tesa Societas Europaea Norderstedt Adhesive tape and method for sheathing elongated material, in particular cables The invention relates to an adhesive tape for sheathing elongated material, in particular cables or cable harnesses, comprising a tape-shaped carrier provided on at least one side with a curable adhesive, and to a method for sheathing elongated material, in particular cable harnesses. Adhesive tapes have been used in industry for some time to produce cable harnesses. The adhesive tapes are used to bundle a large number of electrical cables before installation or in an already assembled state, for example to reduce the space required by the cable bundle by bandaging and to achieve additional protective functions such as protection against mechanical and / or thermal stress.Common forms of adhesive tape include film or textile backings, which are usually coated on one side with pressure-sensitive adhesives. Adhesive tapes for wrapping elongated goods are known, for example, from DE 102013213726 A1, EP 1848006 A2, and EP 2497805 A1. Current cable harnesses wrapped with adhesive tape are generally flexible. However, this is often undesirable for manufacturing reasons. In production, the cable harnesses are usually prefabricated into a cable plan and then inserted into the object to be equipped, such as an automobile. A cable harness plan corresponds to the actual spatial arrangement of the individual cable harnesses in the cable harness. It shows which cable harness is bent at which point and at what angle, the positions of branches or terminations, and which connectors are connected to the ends of the cable harnesses.In order to hold the individual strands of the cable harness in a specific shape so that they can be routed around the engine in the engine compartment, for example, without coming into contact with the engine, injection-molded parts are usually subsequently attached to the adhesive-wrapped cable harness. However, these injection-molded parts have the disadvantage of requiring additional material and assembly costs. Publications DE 102019211178 A1, DE 102019210708 A1, and DE 102019206929 A1 each disclose a method for wrapping elongated items, such as cables or cable harnesses, in which the elongated item is wrapped with an adhesive tape having a curable adhesive applied thereto, in a helical or axial direction, and the adhesive applied to the adhesive tape is activated and cured.The activation and curing of these aforementioned adhesives can occur in various ways, such as through thermal energy, moisture, or light radiation. Moisture and high heat input during the use of cable harnesses are often undesirable, as moisture can have a negative impact on the electrical components through corrosion, for example, and high heat input can attack or even destroy sensitive cable harness components. Therefore, the use of light radiation is resorted to. The use of UV radiation has proven particularly suitable for the activation and curing of adhesive tapes for the sheathing of elongated items. Due to the conditions prevailing in the environment in which the sheathed cable harnesses are used, it is often desirable for the sheathed cable harnesses to be dark in color, particularly black.For example, the engine compartment is often contaminated with dirt, particularly oil and grease, which is significantly less noticeable and therefore less distracting on dark surfaces than on light surfaces. To ensure that the adhesive tapes blend in with this image, they are almost exclusively made of a black, often textile, backing, which gives them a dark appearance. A disadvantage of these adhesive tapes is that, in the wrapped cable harness, where the backing is on the outside, the color of the backing absorbs a large portion, if not all, of the UV radiation required to activate and cure the curable adhesive applied to the side of the backing facing the cable harness.Therefore, experiments were conducted with different colored backings, but these were unsuccessful because either the color impression did not meet customer requirements or the UV radiation permeability was too low to achieve curing of the curable adhesive within the cycle times specified in the automotive industry. Therefore, adhesive tapes with a sufficiently light-colored backing are desirable. This allows sufficient UV radiation to penetrate the backing and reach the adhesive in an acceptable time to activate the curable adhesive and thus meet the cycle times specified in the automotive industry.DE 102019004662 A1 discloses a wrapable and punchable adhesive film comprising an epoxy-based adhesive mass that can be activated by UV radiation or thermally, with a filler mixed into the adhesive mass to create an adhesive film that is compressible in the uncured state, thus enabling tolerance compensation in this stage. JP 2020002203 A discloses an adhesive film that exhibits good releasability while maintaining excellent adhesion between a substrate and an adhesive layer, even when the adhesive layer contains a prescribed functional additive. The adhesive film is provided with a base material and an adhesive layer laminated to a surface of the base material. The adhesive layer (12) is formed from a silicone-based adhesive composition.DE 19846901 A1 teaches an adhesive tape for wrapping elongated material, comprising a fabric carrier based on PE, PP, or polyester, and a colored adhesive applied to one side. Radiation-chemical crosslinking of the adhesive occurs by irradiating the adhesive tape through the carrier material. DE 102007027855 A1 describes a halogen-free, flame-retardant wrapping tape with a film made of thermoplastic polyurethane to which at least one derivative of phosphinic acid is added as a flame retardant, the amount of derivative preferably being 5 to 40 phr. The adhesive can be colored black. The object of the present invention is therefore to provide an adhesive tape for wrapping elongated material that eliminates the disadvantages described above and meets the requirements described above.The object of the present invention is also to provide a method for wrapping elongated material and a product obtainable by the method. This object is achieved by an adhesive tape as described in the independent claim. The subject matter of the dependent claims are advantageous developments of the subject matter of the invention. Furthermore, the invention comprises a method for wrapping elongated material with the adhesive tape and a product obtainable by the method. Accordingly, the invention relates to an adhesive tape of the type mentioned at the outset, in which the tape-shaped carrier is permeable to UV radiation and the curable adhesive is colored, having a CIELAB L* value of <40."Permeable to UV radiation" within the meaning of the present invention means that, with the arrangement described below, "Test Method 3: UV Transmittance," a total energy density of at least 800 mJ / cm² is achieved, measured using a UV Power Puck II and an irradiation time of 30 seconds. If a total energy density of less than 800 mJ is achieved, the corresponding carrier material is not permeable to UV radiation within the meaning of the present invention. A 5 x 7 cm piece of carrier material is irradiated for 30 seconds using an LED UV handheld lamp (from Hönle (Dr. Hönle, based in Gilching)) at a distance of 2 cm. The piece of carrier material to be tested is placed directly onto a UV Power Puck II from Electronic Instrumentation & Technology, Inc., EIT, Sterling, USA. This is used to measure the total energy density of all four wavelength ranges (UVA, UVB, UVC, and UVV) of the radiation transmitted by the carrier.The L* value of the CIELAB color scale is a measure of the brightness of a color. It lies between L*=0 (black) and L*=100 (white). The other values ​​a* and b* are a measure of the hue on the red / green and blue / yellow scales, respectively. These two values ​​are not relevant for the present invention. Because the carrier is permeable to UV radiation and absorbs it only to a limited extent, or not at all, enough energy is available to initiate crosslinking of the curable adhesive and to ensure that curing of the curable adhesive begins within the required process time. The usual cycle time in the automotive industry is less than five minutes. The cycle time determines the process time. The carrier must therefore transmit sufficient UV radiation so that curing of the curable adhesive begins within a maximum of five minutes.This is the case when a total energy density of at least 800 mJ is achieved within 30 seconds in the "UV transmittance test" as described above. Backings that meet this requirement are generally light in color. In combination with conventional adhesive, the use of a light-colored backing material would therefore result in a light-colored adhesive tape on which any type of contamination would be undesirably visible. A white backing material is preferably used. Surprisingly, it has been found that a commercially acceptable adhesive tape can be produced if the curable adhesive is colored and has a CIELAB L* value of < 40. As mentioned above, an L* value of 0 on the CIELAB scale represents black. If the dye or pigment used does not contain any red / green or blue / yellow components, an L* value of 40 would correspond to a dark gray.The color is irrelevant for the present invention. Dark blue, green, or violet tones, for example, can also be used, although dark gray or, in particular, black are preferred. By using the UV-permeable carrier material, the adhesive is not "covered" and thus shielded from UV radiation; rather, the UV radiation can penetrate through the carrier into the adhesive, which thus comes into direct contact with the UV radiation. While a large amount of dye or pigment is usually required in the carrier material to achieve a desired color, a very small proportion of pigment or dye (preferably less than 1% by weight, more preferably less than 0.5% by weight) is often sufficient to color the adhesive. The pigment or dye in the adhesive ensures a dark color of the adhesive tape, even when a light, or even white, carrier is used.A black pigment is preferably used as the pigment. In a particularly advantageous embodiment, the black pigment is carbon black. A well-known commercially available black pigment is Hostatint AN 100 from Clariant. Dark violet, dark green, or dark blue dyes, for example, can be used as dyes. Black dyes are particularly preferred. A well-known commercially available black dye is, for example, Hostatint UV Black N 30 VP 60223 (also Clariant). The carrier material preferably comprises a woven textile, a nonwoven, and / or a film, with textile and nonwoven fabrics being particularly suitable, and nonwoven fabrics being particularly preferred.All known films and textile backings such as knitted fabrics, scrims, ribbons, braids, needle-punched textiles, felts, woven fabrics (including plain weave, twill, and satin weave), warp-knitted fabrics (including warp-knitted fabrics and knits), or nonwovens can be used as backings, whereby "nonwoven" is understood to mean at least textile fabrics according to EN 29092 (1988) as well as stitch-bonded nonwovens and similar systems. An adhesive tape in which a woven fabric, a nonwoven, or a knitted fabric is used as the backing is particularly advantageous. Such backings are described, for example, in WO 2015 / 004190 A1, which is incorporated herein by reference.Stitchbonded fabrics also include thread-layered stitchbonded fabrics, i.e. textile fabrics with one or more superimposed thread layers as the base material, which are consolidated by the stitch formation of integrated knitted threads, for example Florofol; pile thread stitchbonded fabrics, i.e. textile fabrics in which knitted threads formed as a pile are incorporated into a base material by means of stitch formation, for example Malipol; and weft pile stitchbonded fabrics, i.e. textile fabrics in which unmeshed threads formed as a pile are bound to a base material by means of knitted threads by means of stitch formation, for example weft pile. Also preferred are nonwoven fabrics, i.e. textile fabrics that are produced without the use of threads by forming fiber stitches from pre-prepared fiber fleece.These include nonwoven fabrics, i.e., textile sheet structures made of nonwoven fabric with a strengthening fiber mesh side and one side with fibers arranged horizontally to the fiber mesh layer, where fibers from the nonwoven fabric are formed into fiber meshes, for example Malivlies; pile fiber nonwoven fabrics, i.e., textile sheet structures made of nonwoven fabric with or without the use of a base material, which consist of a fiber mesh side and a pile fiber side with fibers arranged almost perpendicular to the fiber mesh layer, for example Voltex, Kunit, or Maliknit; and knitted nonwoven fabrics, i.e., textile sheet structures made of a pile fiber nonwoven fabric, from whose pile fibers a second fiber mesh layer is formed, for example Multiknit or Optiknit. The above definitions are taken from DIN 61211:2005-05. Furthermore, spacer woven and knitted fabrics with lamination can be used. Such spacer fabrics are disclosed in EP 0071212 B1.Spacer fabrics are mat-shaped laminates with a cover layer made of a fiber or filament nonwoven, a base layer, and between these layers, individual or tufts of holding fibers that are needled through the particle layer and distributed across the surface of the laminate, connecting the cover layer and the base layer. Suitable nonwovens include particularly bonded staple fiber nonwovens, but also filament, meltblown, and spunbonded nonwovens, which usually require additional bonding. Mechanical, thermal, and chemical bonding are known as possible bonding methods for nonwovens. Nonwovens bonded by overstitching with separate threads or by intermeshing have proven particularly advantageous.Such bonded nonwovens are produced, for example, on stitch-bonding machines of the "Malimo" type from Karl Mayer, formerly Malimo, and are available from Hoftex Group AG, among others. A Kunit or Multiknit type nonwoven can also be used as a backing. A Kunit nonwoven is characterized by the fact that it is produced by processing a longitudinally oriented fiber nonwoven into a fabric that has stitches on one side and stitch bars or pile fiber folds on the other, but has neither threads nor prefabricated fabrics. Such a nonwoven has also been produced for some time on stitch-bonding machines of the "Malimo" type from Karl Mayer. Such nonwoven stitch-bonded fabrics are known under the name "Maliwatt."A Multiknit nonwoven differs from a Kunit nonwoven in that the nonwoven is bonded by needle piercing on both the top and bottom sides. The starting product for a Multiknit is generally one or two single-sided intermeshed pile fiber nonwoven fabrics produced using the Kunit process. In the final product, both nonwoven top sides are formed into a closed surface by fiber intermeshing and connected to one another by almost vertically positioned fibers. The additional incorporation of further pierceable fabrics and / or scatterable media is also possible. Finally, stitchbonded nonwovens are also suitable as precursors for forming a carrier according to the invention and an adhesive tape according to the invention. A stitchbond is formed from a nonwoven material with a plurality of parallel seams.These seams are created by sewing in or stitch-bonding continuous textile threads. Stitch-bonding machines such as the "Malimo" from Karl Mayer are well-known for this type of nonwoven. Needle-punched nonwovens are also particularly suitable. In needle-punched nonwovens, a fiber web is formed into a flat structure using barbed needles. By alternately inserting and withdrawing the needles, the material is consolidated on a needle bar, whereby the individual fibers intertwine to form a solid flat structure. Also particularly advantageous is a staple fiber nonwoven, which is pre-consolidated in a first step by mechanical processing or is a wet-laid nonwoven that has been hydrodynamically laid, with between 2% and 50% by weight of the fibers of the nonwoven being melt-bonded fibers, in particular between 5% and 40% by weight of the fibers of the nonwoven.Such a nonwoven fabric is characterized in that the fibers are laid wet or, for example, a staple fiber nonwoven fabric is pre-consolidated by forming loops from the fibers of the nonwoven fabric through needling, sewing, air and / or water jet processing. In a second step, heat setting takes place, whereby the strength of the nonwoven fabric is further increased by the melting or fusing of the melt fibers. Advantageously, and at least in some areas, the carrier has a smooth-ground surface on one or both sides, preferably a completely smooth surface in each case. The smooth-ground surface may be chintzed, as explained, for example, in EP 1448744 A1. In this way, the repellency of dirt is improved.The starting materials for the carrier are, in particular, (chemical) fibers (staple fibers or continuous filaments) made of synthetic polymers, also called synthetic fibers, made of polyester such as polyethylene terephthalate, polyamide, polyimide, aramid, polyolefin, polyacrylonitrile, or glass, (chemical) fibers made of natural polymers such as cellulosic fibers (viscose, modal, lyocell, cupro, acetate, triacetate, cellulon), such as rubber fibers, such as plant protein fibers and / or animal protein fibers and / or natural fibers made of cotton, sisal, flax, silk, hemp, linen, coconut, or wool. However, the present invention is not limited to the materials mentioned; rather, a multitude of other fibers can be used to produce the nonwoven fabric without requiring inventive activity, as will be apparent to the person skilled in the art. Furthermore, yarns made from the specified raw materials are also suitable.In woven or non-woven fabrics, individual threads can be made from a blended yarn, meaning they contain both synthetic and natural components. However, the warp and weft threads are usually made from the same material. Polyester is the preferred material for the backing due to its outstanding resistance to aging and chemicals and operating media such as oil, gasoline, antifreeze, and the like. Polyester also has the advantage of producing a highly abrasion- and temperature-resistant backing, which is particularly important for the specific application of bundling cables in automobiles, for example, in the engine compartment. The basis weight of the backing is advantageously between 30 g / m. 2 and 300 g / m 2 further advantageous between 50 g / m 2 and 200 g / m 2 , particularly advantageous between 50 g / m 2 and 150 g / m 2, particularly advantageous between 70 g / m 2 and 130 g / m 2 According to a particularly advantageous embodiment of the invention, a woven fabric or nonwoven fabric made of polyester is used as the carrier, which has a basis weight between 50 g / m 2 and 150 g / m 2 Preferably, the curable adhesive is of low viscosity. Low viscosity in the context of the present invention means that the viscosity, measured using an Anton Paar MRC 302 compact rheometer according to DIN EN ISO 3219:1994-10, is at least in the range of 250 to 1000 mPa*s at a shear rate of 1 s -1The low-viscosity, dark-colored adhesive penetrates so deeply into the (for example, white) nonwoven backing and encloses the fibers, creating a dark appearance. The curable adhesive can be activated in various ways, for example, by means of thermal energy, moisture, or pressure. Particularly preferably, within the meaning of the present invention, the curable adhesive is activated by means of radiation energy. According to the invention, a structural adhesive (construction adhesive, assembly adhesive) is used as the curable adhesive (see Römpp, Georg Thieme Verlag, document identifier RD-19-04489, last updated: September 2012).According to DIN EN 923:2006-01, structural adhesives are adhesives that form bonded joints that can maintain a specified strength in a structure for a specified, extended period of time (according to the ASTM definition: "bonding agents used for transferring required loads between adherends exposed to service environments typical for the structure involved"). They are therefore adhesives for bonds subject to high chemical and physical stresses, which, when cured, contribute to the strengthening of the bonded substrates and are used in the production of constructions made of metals, ceramics, concrete, wood, or reinforced plastics. The structural adhesives according to the invention are based in particular on reactive adhesives (phenolic resins, epoxy resins, polyimides, polyurethanes, and others). The adhesive can be elastic after curing to ensure a durable sheath that is resistant to vibration and torsion.In a further advantageous embodiment, a thermally curable, meltable adhesive is used as the curable adhesive, comprising an epoxy-functionalized acrylonitrile / butadiene copolymer with an average of more than 1.5 epoxy groups per molecule and the ground reaction product of phthalic anhydride and diethylenetriamine dissolved, as described in DE 102019211178 A1. Advantageously, the total thickness of the applied curable adhesive is between 20 μm and 500 μm, more advantageously between 100 μm and 400 μm, particularly advantageously between 200 μm and 325 μm. In a further advantageous embodiment, the adhesive tape is provided with a pressure-sensitive adhesive on at least one side of the tape-shaped carrier.Because the pressure-sensitive adhesive exhibits good tack and adhesion to the material to be wrapped, even after activation of the adhesive tape's curable adhesive, positioning and processing of the adhesive tape is made considerably easier. For example, the adhesive tape's positioning can be corrected if it was not immediately positioned correctly. Furthermore, the positioning is maintained and cannot slip if the curable adhesive loses its (instant) adhesive strength after activation. This means that even vibration does not disrupt the positioning. Adequate shaping and good protection of the cable harness are ensured. Particularly preferably, the adhesive tape is provided with a curable adhesive on one side of the tape-like carrier, and a layer of a pressure-sensitive adhesive is applied to the curable adhesive.In this way, the pressure-sensitive adhesive is in direct contact with the item to be wrapped upon application and can particularly well ensure an adhesive bond to the item that persists even after the curable adhesive has cured. Slipping of the adhesive tape on the item to be wrapped can thus be reliably prevented. According to one embodiment of the invention, the elongated item is a cable harness comprising a bundle of several cables, such as 3 to 1000 cables, preferably 10 to 500 cables, in particular between 50 and 300 cables. Preference is given to pressure-sensitive adhesives as described in the published European patent applications EP 2520627 A1, EP 2522705 A1, EP 2520628 A1, EP 2695926 A1, EP 2520629 A1 and EP 3433330 A1, to which reference is made here. In a particularly preferred embodiment, the curable adhesive is pressure-sensitive. In other words, a curable pressure-sensitive adhesive can be used as the adhesive.This is achieved in particular by adding crosslinking-capable compounds to the pressure-sensitive adhesive. As used here, the term crosslinker refers to chemical compounds capable of linking molecular chains together so that two-dimensional structures can form three-dimensional crosslinked structures through the formation of intermolecular bridges. Crosslinkers are compounds—particularly bi- or polyfunctional, usually low-molecular-weight compounds—that, under the chosen crosslinking conditions, can react with suitable—particularly functional—groups of the polymers to be crosslinked, thus linking two or more polymers or polymer sites together (“forming bridges”) and thus creating a network of the polymer(s) to be crosslinked. This generally results in an increase in cohesion.Typical examples of crosslinkers are chemical compounds that contain two or more identical or different functional groups within the molecule or at both ends of the molecule and can therefore crosslink molecules of identical or different structures. Furthermore, a crosslinker can react with the reactive monomer or reactive resin without polymerization in the true sense of the word occurring. The finished coated material is preferably cut to a width of 20±2 mm (any other width is also conceivable) and, when used for wrapping elongated material, is wound spirally with a 50% overlap around the elongated material—like a cable bundle. The finished coated material can be covered with a liner.The present invention also relates to a method for wrapping elongated items, such as lines or cable harnesses, wherein an adhesive tape as described above is guided in a helical line around the elongated item or the elongated item is wrapped in the axial direction by the adhesive tape, the elongated item together with the enclosing adhesive tape is brought into the desired arrangement, in particular in the cable harness plan, the elongated item is held in this arrangement, and the curable adhesive is cured by UV radiation. In the first alternative, the adhesive tape is guided in a helical movement around the elongated item. This results in the shape of a helix (also called screw, helical line, cylindrical spiral or helix; helix is ​​a curve that winds around the surface of a cylinder with a constant pitch).The tape is preferably wrapped spirally around the elongated material with an overlap of 30% to 70%, more preferably 40 to 50%, in particular approximately 50%. In the second alternative, the elongated material is wrapped by the adhesive tape in the axial direction. The wrapping of a cable harness with the described adhesive tape is not carried out in a helical manner, as is usual, but in such a way that a longitudinal axis of the tape is aligned essentially parallel to the direction of travel of the cable harness. Viewed in cross-section, the adhesive tape lies around the cable harness in the shape of an Archimedean spiral. This type of winding is also called "wrapping the cable harness" (also known in the art as "cigar wrapping"). Finally, the present invention also relates to a cable harness wrapped with the cured adhesive tape according to the invention and to a cable harness produced by the method according to the invention.The adhesive tape will be explained in more detail below with the aid of several figures, without intending to create any kind of limitation. Figure 1 shows the adhesive tape in a lateral section, Figure 2 shows a section of a cable harness consisting of a bundle of individual cables and covered with the adhesive tape according to the invention, and Figure 3 shows an advantageous application of the adhesive tape. Figure 1 shows a transverse section (cross-section) of the adhesive tape, which consists of a fabric carrier 1 to which a layer of a self-adhesive coating 2 based on an acrylate dispersion is applied on one side. The adhesive has sunk 20% into the carrier, which ensures optimal anchoring and at the same time improves the hand tearability of the carrier.Figure 2 shows a section of a cable harness comprising a bundle of individual cables 7 and sheathed with the adhesive tape 11 according to the invention. The adhesive tape is guided in a helical movement around the cable harness. The section of the cable harness shown shows two windings I and II of the adhesive tape. Further windings would extend to the left; these are not shown here. In a further embodiment for a sheathing, two tapes 60, 70 according to the invention, provided with an adhesive, are laminated to one another with their adhesives offset (preferably by 50% each), resulting in a product as shown in Figure 3.Examples: Test method 1 - Bending test to determine stiffness A test sample consisting of 250 individual wires with a wire cross-section of 0.35 mm² is bundled into a sample wire harness using 9 mm wide adhesive tape (tesa 51618) so that the sample wire harness has a diameter of 23±5 mm and a length of 300±50 mm. This sample wire harness is wrapped helically with the stiffening material, ensuring a 50% overlap. The stiffening material is then treated with UV radiation. The hardened sample wire harness is subjected to a bending test to determine the influence of the stiffening material on stiffness. The bending test is carried out on a tensile testing machine. For this purpose, the sample wire harness is placed on two jaws 70 mm apart and pressed in the center with a compression fin by a distance of 30 mm and loaded.The force required to deform the test path is recorded in Newtons by a tensile testing machine. The test speed is 100 mm / min, both during loading and unloading of the sample cable harness. The test is performed at three different points on the cable harness (beginning, middle, and end).The bending force results from the mean value of the three individual measurements and is assessed in three categories as follows: Assessment categories 3-point bending test: + Requirement met to be used as a stiffening adhesive tape (> 40 N) O Requirement partially met to be used as a stiffening adhesive tape (40 to 30 N) - Requirement not met to be used as a stiffening adhesive tape (< 30 N) Test method 2 - Colour requirement The appearance of the adhesive tape was assessed according to the CIELAB colour scale: + Requirement met (dark appearance according to CIELAB colour scale with L* value of < 40) - Requirement not met (light appearance according to CIELAB colour scale with L* value of > 40) Test method 3 - UV transmittance The test method for measuring the UV radiation passing through a carrier material has already been described in detail above.The following levels of assessment were used: + Requirement met to start curing within the required process time (intensity > 1,000 mJ / cm. 2 ) O Requirement partially met to start curing within the required process time (intensity 1,000 to 800 mJ / cm 2 ) - Requirement not met to start curing within the required process time (intensity < 800 mJ / cm 2 ) Adhesive tape production The following composition generally applies to coating with a curable solvent-based adhesive: 15 to 50 wt.% matrix 49.9 to 82 wt.% epoxy resin 0.1 to 5 wt.% photoinitiator The matrix can be based on various bases, as long as epoxy functions are included. Additionally, polyols such as polyether or polyester polyols can be used to adjust elasticity. Example 1 – Adhesive tape production To produce the adhesive according to Example 1, 35 parts by weight of Levamelt 700 (Arlanxeo), 40 parts by weight of Araldite GT7072 (Huntsman), and 25 parts by weight of Araldite GY250 (Huntsman) are weighed and mixed with butanone to achieve a solids content of 60%. Dye dispersions or solid dye powder (see below) are added to this adhesive solution. The dye dispersions or solid dye powder are incorporated while stirring. The colored adhesive is spread on a coating table onto PET release paper and then dried in a convection oven at 105 °C to give a basis weight of 290 g / m². The dried coatings are then laminated onto a nonwoven backing (spunbond) and cut into strips.Based on 99.97 g or 99.25 g of solids in the adhesive (i.e., without taking into account the solvent butanone), the following dyes are added to the adhesive for the individual examples: 1a) 0.03 g of Hostatint AN 100 from Clariant, 1b) 0.75 g of Graphtol black from Clariant, and 1c) 0.03 g of Hostatint UV Black N 30 VP 6023 from Clariant. Hostatint AN 100 and Hostatint UV Black N 30 VP 6023 are dye dispersions with a solids content of 21%. The solvent of the dye dispersions is also not taken into account when specifying the compositions. Graphtol black is a powdered dye. In order to find a suitable carrier, various carriers were tested in advance using test method 3. The results are shown in Table 1 below. Table 1:. Given its energy density, the white spunbond nonwoven was selected as the carrier material. The results of the three test procedures for examples 1a) to 1c) with the different pigments / dyes are listed in Table 2 below. Table 2: The results show that the requirements are met in all three parameters when using Hostatint AN 100. An adhesive tape using Graphtol Black, on the other hand, does not meet the color requirements, while the required flexural strengths cannot be achieved when using Hostatint UV Black N 30 VP 6023. The color requirement in Example 1a can also be achieved with higher dye concentrations, but UV transmission and thus curing are significantly impaired at concentrations of 0.1% and above.

Claims

Patent claims 1. Adhesive tape for wrapping elongated material, such as in particular wires or cable harnesses, comprising a band-shaped carrier provided on at least one side with a curable adhesive, characterized in that the band-shaped carrier is permeable to UV radiation and the curable adhesive is colored, wherein it has a CIELAB L* value of < 40.

2. Adhesive tape according to claim 1, characterized in that the carrier material comprises a woven textile fabric, a nonwoven fabric and / or a film.

3. Adhesive tape according to claim 2, characterized in that the basis weight of the textile carrier is between 30 g / m 2 and 300 g / m 24. Adhesive tape according to one of claims 1 to 3, characterized in that the curable adhesive contains a pigment or a dye, in particular a black pigment or a black dye.

5. Adhesive tape according to one of claims 1 to 4, characterized in that the curable adhesive is activated by means of radiation energy.

6. Adhesive tape according to one of claims 1 to 5, characterized in that the curable adhesive is pressure-sensitively adhesive. 7.Method for sheathing elongated material, such as in particular lines or cable harnesses, wherein an adhesive tape according to one of the preceding claims is guided in a helical line around the elongated material or the elongated material is enveloped in the axial direction by the adhesive tape, the elongated material together with the enclosing adhesive tape is brought into the desired arrangement, in particular into the cable harness plan, the elongated material is held in this arrangement and the curable adhesive is caused to cure.

8. Method for sheathing elongated material, such as in particular lines or cable harnesses, wherein an adhesive tape according to one of claims 1 to 6 is first activated and immediately then wrapped in a helical line around the. elongated material is guided or the elongated material is wrapped in the axial direction by the adhesive tape, the elongated material is then brought together with the enveloping adhesive tape into the desired arrangement, in particular into the cable harness plan, and is held in this arrangement while the curable adhesive cures.

9. A cable harness that is wrapped with an adhesive tape according to one of claims 1 to 6 or that can be produced by a process according to one of claims 7 to 8.

10. Use of the adhesive tape according to one of claims 1 to 6 for wrapping elongated material, such as in particular lines or cable harnesses.

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