EP1132927A2 - Use of a scotch tape as envelopping tape for cable - Google Patents

Abstract

The use of an adhesive tape (I) is claimed as a wrapping tape for cables having polyvinyl chloride (PVC)-free cladding, where: (a) (I) consists of a PVC-free carrier coated on at least one side with an acrylate-based pressure sensitive adhesive (II); and (b) adhesion of (I) to the cable at 100 degrees C or more for at least 240 hours causes no damage to the cladding.

Description

The invention relates to the use of an adhesive tape as a taping tape for cables, the cables have a PVC-free sheathing.

Electrical and electromechanical components as well as the sheathing of electrical lines often consist of polymeric materials, with polyvinyl chloride (PVC) represents the most important plastic, historically due to its availability and its excellent material and insulation properties.

In particular, sheaths of copper wires consist predominantly of PVC, provided that not enforce framework conditions such as high temperature requirements alternatives.

For the mechanical and electrical protection of such cables are in the past Self-adhesive tapes have been developed as generally for protection and insulation as well for bandaging electrical cables and components to a considerable extent Self-adhesive tapes can be used.

The self-adhesive tapes make it possible to produce a long-term bond without damage to the cable due to interactions between the adhesive tape and the cable sheath. The additives in the plasticized PVC, in particular, tend to migrate and require adhesive tapes specially adapted to them.
This is why adhesive tapes with a PVC film backing have become particularly popular; on the one hand because of their mechanical properties, but on the other hand also because of minimized compatibility problems, since at least the backing and the primer consist of the same material.

For special applications such as wrapping cable strings or cable harnesses in household appliances, machines and in particular vehicles are also self-adhesive tapes widely used which is a textile carrier, for example a polyester or Cellulosic tissue.

In the context of discussions about the environmental impact of PVC, there is a tendency to replace this material with alternatives. Electrical components and auxiliary parts as well the sheathing of copper cables is reinforced with other plastics, being for higher requirements in addition to fluoropolymers and thermoplastic elastomers like Arnitel® [DSM Engineering Plastics] or Hytrel ® [DuPont] mainly polyester plastics are used.

Find for the cost-sensitive mass range with lower temperature requirements increasing use of polyolefinic materials, especially since through metallocene technology similar mechanical property profiles can be set as that of soft PVC, the polyolefins additionally per se due to their chemical Composition as pure hydrocarbons have excellent insulation effects.

The tendency towards such PVC-free lines is also for cable sets in vehicles given, while components such as plug connections, switches, creased pipes, etc. are already predominant made of PVC-free materials.

Electrical wiring harnesses or components that are wrapped with self-adhesive tapes, must function reliably over the entire service life of the overall product, such as that of a vehicle. When choosing unsuitable Adhesive tapes can cause incompatibilities during product life, the damage to the cables can lead to extreme embrittlement - corrosion and short circuits with the risk of failure of the entire electrical system / electronics the possible consequence. Especially for vehicles such as passenger cars or trucks very high demands are placed on tolerance; in the passenger compartment peak temperatures of up to 80 ° C can occur, in the engine compartment even higher continuous temperatures.

That is why a long-term test of over 3000 has proven itself for the area of application of the cable winding tapes Hours, for example according to FORD specification S95 GG 14K 024 BA, as a standard test enforced - sample cable sets are stored at the test temperatures and after defined periods, usually every 500 hours, around a mandrel with defined Diameter bent and then examined for damage; this test is running over a total duration of 3000 hours. In addition to purely visual appraisal, some an electrical insulation test is also carried out. The test temperatures are correct according to the areas of application of the cable sets and are, for example, 90 ° C for fabric tapes with use in the passenger compartment according to FORD S95 GG 14K 024 BA. For applications Continuous temperatures of 125 ° C and higher are also required in the engine compartment.

Adhesive tapes with a tape-shaped are known for such cable winding applications Carriers based on fabric or sewing fleece, whereby fabric tapes have been around for a long time are available and tapes with a non-woven backing, for example in DE 94 01 037 U1 to be discribed. Pressure sensitive pressure sensitive adhesive coatings are preferred as the adhesive coating used.

DE 44 42 092 C1 describes such an adhesive-based adhesive tape, which is on the back of the carrier is coated. DE 44 42 093 C1 also includes the use of a fleece as a carrier for an adhesive tape, here one is formed by the formation of stitches described the fibers of the nonwoven reinforced cross-fiber nonwoven, so a specialist fleece known as Malivlies. DE 44 42 507 C1 also discloses a Adhesive tape for cable banding, but it is based on so-called Kunit or Multi-knit fleece.

DE 195 23 494 C2 discloses the use of an adhesive tape with a carrier made of nonwoven material for bandaging cable harnesses, which is coated on one side with an adhesive. The fleece used according to the invention is a spun fleece made of polypropylene, which is thermally consolidated and embossed with the aid of a calender, the embossing roller having an embossing area of 10% to 30%, preferably 19%.
DE 298 04 431 U1 also discloses the use of an adhesive tape with a carrier made of nonwoven material for bandaging cable harnesses, the proposed spunbonded nonwoven made of polyester.

DE 298 19 014 U1 discloses adhesive tapes based on air and / or water jets consolidated nonwovens known. The disadvantage of these carriers is, despite this solidification, that through this technique a pulling out of long threads and the negative influence the technical adhesive properties cannot be excluded. With very strong Solidification of the carrier can have other advantageous properties especially for the Bundling of cables in automobiles can no longer be obtained.

An adhesive tape is described in WO 99/24518 A1, the backing material being a nonwoven which is suitable for the use of adhesive tapes only through the specific selection of fibers or filaments with a fineness of greater than 15 den and through an additionally extruded film layer . A disadvantage for the use is not only the additional extrusion coating required, but also the limitation to very thick fiber material. This results in a coarse fleece that lacks the typically soft, textile character. Denier [den] is a French textile unit for the titer (fineness) of yarn. The unit results from the equation: Titer = Thread mass Thread length , a thread having the denier of one denier [1 den] if the weight of a 9000 m long thread is 1 g, corresponding to 1 g / 1000 m = 9 den. (cf.Römpp Lexikon Chemie - Version 2.0, Stuttgart / New York, Georg Thieme Verlag 1999).

The intended substitution of PVC with polyolefins in particular shows that Self-adhesive tapes previously used consistently have problems with long-term compatibility exhibit. The range of damage occurring ranges from slight cracking in the cable sheathing from embrittlement to complete failure Crumble of components and cable sheaths after long storage.

The generally good compatibility of the adhesive tapes with silicone adhesives is known almost all plastics in electrical engineering, but there are tapes with silicone adhesives due to the high costs and low availability hardly used. Furthermore, siliconized products are used in the automotive sector if possible because of the potential danger to (repair) paintwork and electronics avoided due to similar hazard potentials.

The invention has for its object an adhesive tape for use as a bandaging tape to provide for cables, the cables being a PVC-free sheathing have, so especially one made of polyester or polyolefins. The tape should not be glued in direct contact during normal use Damage to the casing. An object of the invention is therefore that Disadvantages of the prior art completely or at least to a considerable extent remedy.

Unpredictable and completely surprising for the person skilled in the art, the adhesive tape described below according to the invention is capable of fulfilling the tasks set.
To achieve the object, the invention proposes the use of an adhesive tape as a taping tape for cables, the cables having a PVC-free sheathing, comprising a PVC-free backing on which at least one side has a pressure-sensitive adhesive based on acrylate applied, the adhesive tape, if it is glued to the cables at a temperature of at least 100 ° C and for a period of at least 240 h, the jacket will not be damaged.

In a preferred embodiment, the adhesive can be coated as pure acrylate, as a compound and / or as a blend from the solution, as an aqueous system or as a hot melt from the melt.
Compounds are understood to be ready-to-use mixtures of polymers and the corresponding additives which are required for the production of the end products. Blends are blends or mixtures of polymers.

For the compatibility between PVC-free cables and components as well as the adhesive tape the adhesive is of decisive importance on the part of the adhesive tape. By Direct contact can cause migration processes to change the plastic composition and thus also the properties: this applies both to the adhesive and their adhesive properties as well as especially for plastic wrapping Cables and the mechanical and electrical properties.

According to the invention, the use of an adhesive tape with a particularly preferred Adhesive based on acrylic hot melt the task. Solvent-free systems based on acrylate hotmelt, as they can be used in an excellent way for this, are commercially available in EP 621 326 or also in EP 937 761 they are, for example, from BASF under the name acResin UV®.

Outstanding adhesives are suitable which have a K value of at least 20, in particular greater than 30, measured in each case in 1% strength by weight solution in toluene at 25 ° C. The K value is determined in particular in analogy to DIN 53 726.
Adhesives of this type can be obtained, for example, by concentrating a solution of a composition having the abovementioned properties to form a system which can be processed as a hot melt.
Concentration can take place in appropriately equipped boilers or extruders, particularly in the case of the associated degassing, a degassing extruder is preferred.

Advantageous adhesives are e.g. B. in DE 43 13 008 A1. The one on this The solvent is completely removed in an intermediate step by means of the acrylic compositions prepared withdrawn.

In addition, further volatile constituents can optionally be removed. After coating from the melt, these masses have only a small amount Volatile components. Thus, all of those claimed in the above-mentioned patent can Monomers / recipes are adopted. Another advantage of the patent masses described can be seen in the fact that these have a high K value and thus have a high molecular weight. The skilled worker is aware that systems with higher molecular weights crosslink more efficiently. This decreases the Volatile components.

In a form which is very suitable according to the invention, the solution of the mass contains 5- 80 wt .-%, in particular 30-70 wt .-% solvent.

Commercial solvents are preferably used, especially low boiling hydrocarbons, ketones, alcohols and / or esters.

Single-screw, twin-screw or multi-screw extruders are further preferred used with one or in particular two or more degassing units.

The adhesive can by chemical or thermal treatment, in particular by radiation chemical treatment, be crosslinkable. The acrylic hot melt adhesive can be cross-linked preferably with UV radiation. Other types of networking are also possible, for example electron beam crosslinking.

The acrylic hot melt adhesive can be in an excellent embodiment the invention additionally radiation-chemically and / or chemically and / or thermally activatable substances can be added and / or polymerized into them, in particular Photoinitiators, especially benzoin derivatives. As examples of this and without wanting to restrict yourself unnecessarily are benzoin acrylate or benzoin methacrylate, acrylic acid or called methacrylic acid ester. Such benzoin derivatives are in EP 0 578 151 A described.

In a particularly preferred embodiment, copolymers are used as self-adhesive compositions from (meth) acrylic acid and its esters with 1 - 25 C atoms, maleic, fumaric and / or itaconic acid and / or its esters, substituted (meth) acrylamides, maleic anhydride and other vinyl compounds, such as vinyl esters, especially vinyl acetate, Vinyl alcohols and / or vinyl ethers used.

The residual solvent content should be less than 1% by weight.

According to the invention, only PVC-free fabrics are used as carrier materials for the adhesive tape Entrance to continue after the manufacture of the insulation or protective winding PVC-free composites are available. For example, fabrics, knitted fabrics, Nonwovens, foils, paper, felts, foams and coextrudates are used.

Instead of the soft PVC films, stretchable, conformable films are preferred Plastics such as polyolefins or, in particular, textile carrier materials selected.

The textile backing materials include woven or knitted fabrics made from natural fibers such as Cotton or synthetic fibers such as polyester, polyamide, polyethylene, polypropylene, Cotton wool and the like known; Furthermore, a wide variety of fleece carriers such as wet-laid Nonwovens, hydroentangled nonwovens or thermally bonded with or without pressure Nonwovens, needle-punched or spunbonded fabrics, stitchbonding fabrics such as Maliwatt or Malivllies be used, provided they are made from suitable fibers or filaments. Of felts, foams and other types of PVC-free substrates can also be used be used.

Pre-consolidated nonwovens are produced, for example, on sewing-knitting machines of the "Malivlies" type from Karl Meyer, formerly Malimo, and can be obtained from Naue Fasertechnik and Techtex GmbH, among others. A Mali fleece is characterized in that a cross fiber fleece is consolidated by the formation of meshes from fibers of the fleece.
A fleece of the type Kunitvlies or Multiknitvlies can also be used as a carrier. A Kunitvlies is characterized in that it results from the processing of a longitudinally oriented nonwoven fabric to form a fabric that has loops on one side and mesh webs or poly fiber folds on the other, but has neither threads nor prefabricated fabrics. Such a fleece has also been produced for a long time, for example, on sewing-knitting machines of the "Kunitvlies" type from Karl Mayer. Another characteristic feature of this fleece is that it can absorb high tensile forces in the longitudinal direction as a longitudinal fiber fleece. A multi-knit fleece is characterized in comparison to the Kunit fleece in that the fleece is strengthened both on the top and on the bottom by piercing with needles on both sides.
Finally, nonwovens are also suitable as a preliminary product to form an adhesive tape according to the invention. A sewing fleece is formed from a fleece material with a plurality of seams running parallel to one another. These seams are created by sewing or sewing continuous textile threads. Sewing-knitting machines of the "Maliwatt" type from Karl Mayer, formerly Malimo, are known for this type of fleece.

The starting materials for the textile backing are in particular polyester, polypropylene, Viscose or cotton fibers are provided. However, the present invention is not limited to the materials mentioned, but it can be recognized by those skilled in the art a large number of other fibers for production without having to be inventive of the fleece can be used.

The basic fibers of the nonwoven preferably consist of polyester fresh or polyester tear fibers. Fibers with a fiber length between 10 and 100 are particularly suitable mm and a fiber thickness of 1.5 to 10 dtex.

A particularly suitable application of the adhesive tape according to the invention is the use as a taping tape for cables, the cables having a PVC-free sheathing.
In addition to the usual cables, the term “cable” is also to be understood to mean further ones, for example plug connections, switches or corrugated tubes and the like, which are used in the area of the cable harness.
PVC-free cable sheathings made from thermoplastic elastomers, fluoropolymers and polyolefins, but also from all other PVC-free plastics, can be used. Polypropylenes, PP / PE copolymers or PP / PE compounds and crosslinked polyethylenes may be mentioned here as non-exclusive examples which can be used in an outstanding manner.

Acrylic hotmelts can be applied to the carriers mentioned in a variety of ways. In addition to the standard application methods such as direct coating from nozzles, via rollers etc. are also transfer processes with regard to the open structure of textile carriers advantageous, as disclosed in DE 43 24 748 C2. The adhesive mass first applied to an endless, anti-adhesive webbing and then in a laminating station ― if necessary using pressure and temperature to improve the mass anchorage - transferred to the carrier material.

The desired technical adhesive properties such as adhesive strength, tackiness (tack) and cohesion can to some extent be determined by the final radiation chemical Control networking and adapt it to requirements. The rolling up of the carrier material too large bales represent the end of the actual coating process.

Adhesive tapes according to the invention, which are produced by cutting or parting from larger bales in the desired dimensions, can be selected for bandaging cables with PVC-free sheaths, with one of the main applications for the production of wire harnesses in vehicles producing a large number of individual cables by wrapping the whole Bundle is bandaged into a strand. Adequate adhesion of the adhesive tape on the cable sheathing and on the back of the carrier are important properties that the adhesive tape must have for a permanent bandaging of such cable harnesses.
For this purpose, adhesive strengths in particular of more than 1 N / cm, in particular greater than 2 N / cm, are required, and adhesive compositions which are more than 15 g / m ^{2 in} the case of smooth film backings, more than 25 g / m ² in the case of textile backings, preferably 50 to 200 g / m ² , depending on the nature of the textile backing.

Cable sets bandaged with adhesive tapes according to the invention are largely standardized Subject to tests, which are usually found in special automotive standards or find electrical equipment manufacturers - for compatibility testing is often used as a long-term test the so-called "3000 hour test", e.g. according to FORD S95GG 14K024 BA.

This test is carried out as a short-term rapid test over 10 days at an elevated temperature.
According to the invention, the adhesive tape, if it is stuck to the cables at a temperature of at least 100 ° C. and for at least 240 h, does not damage the sheathing. The duration is preferably 480 hours, ie 24 days, during which no damage occurs.
If the adhesive tape is bonded in applications at a higher temperature, the requirements also increase. The adhesive tape / cable composite also withstands temperatures above 125 ° C., particularly preferably 150 ° C.

In the above-mentioned rapid tests, the test temperatures are 20 to 25 ° C higher chosen as the temperatures that actually occur during bonding to later Definitely exclude impairment of the casing. For the suitability level 3000h / 125 ° C the fastest tests take place at 150 ° C for at least 10 days.

While there are tapes that are predominantly based on natural rubber and synthetic rubber adhesives are based, in many cases as problematic with regard to tolerance prove, is a significant improvement with the self-adhesive tape of the invention to reach.

In addition to the improvements in compatibility, the self-adhesive tapes according to the invention offer With an acrylate adhesive, there is further potential compared to most in the past Use adhesive tapes. By choosing the polymer polyacrylate that without large proportions of admixing components such as resins, plasticizers etc. and whose cohesion is significantly increased by networking, is compared to natural and synthetic rubber adhesives an improvement in temperature resistance, achieved both in terms of peak and permanent loads.

The increased temperature resistance of the adhesive comes with a suitable carrier selection can also be used for the entire adhesive tape.

In particular in a combination of the adhesive mentioned with a carrier made of polyester, a plastic that is known for good temperature resistance and in Range of electrical adhesive tapes up to and including temperature class B (130 ° C continuous load), in some cases even class F (155 ° C continuous load) can be used finds, can meet the demands on the tapes for increased durability become.

The adhesive tape according to the invention is described below using examples without wanting to limit the invention unnecessarily.

Example 1:

A UV-crosslinkable acrylic hot-melt adhesive of the Acronal® DS 3458 type is applied to a textile carrier of the Maliwatt type of nonwoven thread sewing fabric (80 g / m ² , fineness 22, black, thickness approx. 0.3 mm) using a nozzle coating applied at 50 m / min. The temperature load on the carrier is reduced by means of a cooled counter-pressure roller. The mass application is approx. 65 g / m ² . A suitable crosslinking is achieved inline prior to winding up by irradiation with a UV system which is equipped with 6 medium-pressure mercury lamps of 120 W / cm.

Example 2:

On the same nonwoven backing as in Example 1, about 50 g / m ^{2 of the} same adhesive is transferred as a film in the transfer process via a roller bar nozzle at a speed of 10 m / min using belt tape, with a pressure in the laminating station to improve the bond strength between the backing and the adhesive layer of 8 bar and a temperature of the counter pressure roller of approx. 70 to 80 ° C is used. The melting temperature of the adhesive is approx. 100 ° C. The crosslinking is carried out as described in Example 1, but the emitter power is adapted in accordance with the lower coating speed.

Both samples are separated by winding into bars and parting into commercially available rolls of tape of 10 m and checked for their properties.
With bond strengths on steel of> 2.5 N / cm and on the back of> 3.5 N / cm, both samples surely meet the requirements for cable winding tapes (the bond strengths are measured at 180 ° according to international standards with a pull-off speed of 300 mm / min).

For the compatibility check, the test method described is used, which is used routinely by automobile manufacturers such as Renault, Peugeot etc.
The sample cable sets are stored at 100 ° C for 240 hours or at 150 ° C for 240 hours.

For the production of samples, single-core test cables (preferred wire cross-sections of 0.35 or 0.75 mm ² ) from different manufacturers are wrapped with the adhesive tape with jackets based on polyolefins; After storage, the adhesive tape is removed, the cable is bent around itself (very high stress due to the narrow bending radius) and examined for damage, namely a visual assessment of embrittlement and cracking, and a breakdown voltage test with 1 kV for 1 minute.

The results listed in the table apply to adhesive tapes according to Examples 1 and 2 based on an acrylic hot melt adhesive of the acResin type.

As a comparative example is a known standard adhesive tape for bandaging PVC-coated Cables based on a natural rubber adhesive.

Prüftemperatur: 100 °C für Klasse 1 (Dauertemperaturbeständigkeit 80°C);

Prüftemperatur: 150 °C für Klasse 3 (Dauertemperaturbeständigkeit 125°C).

Temperatur- klasse Kabel- hersteller Kabel- typ Kompatibilität mit Klebeband 1 und 2 (Acrylat-Hotmelt) Kompatibilität mit Stan- dardklebeband für PVC-Kabel (Naturkautschuk) Klasse 1 (80 °C) A PP i.O. (>480 h) B PE i.O. (> 480 h) Klasse 3 (125 °C) C PP i.O. (>240 h) n.i.O. (ca. 100 h) D PP/PE n.i.O. (ca. 200 h) n.i.O. (ca. 100-150 h) E PE i.O. (>240 h) n.i.O. (ca. 175-200 h) F PP/PE i.O. (> 480 h) i.O. (> 240 h) The test is considered passed (assessment: OK) if no damage can be determined after 240 hours (corresponding to 10 days at an elevated storage temperature)

Test temperature: 100 ° C for class 1 (permanent temperature resistance 80 ° C);

Test temperature: 150 ° C for class 3 (permanent temperature resistance 125 ° C).

Temperature class Cable manufacturer Cable type Compatibility with adhesive tape 1 and 2 (acrylate hot melt) Compatibility with standard adhesive tape for PVC cables (natural rubber) Class 1 (80 ° C) A PP OK (> 480 h) B PE OK (> 480 h) Class 3 ( 125 ° C) C. PP OK (> 240 h) not ok (approx. 100 h) D PP / PE not ok (approx. 200 h) not ok (approx. 100-150 h) E PE OK (> 240 h) not ok (approx. 175-200 h) F PP / PE OK (> 480 h) OK (> 240 h)

Claims (12)

Use of an adhesive tape as a taping tape for cables, the cables have a PVC-free sheath comprising a PVC-free support on which A pressure-sensitive adhesive based on acrylate is applied to at least one side is, the adhesive tape when it is at a temperature of at least 100 ° C and for a duration of at least 240 h is glued to the cables, to no damage the sheathing leads. Adhesive tape according to one of the preceding claims, characterized in that the adhesive is coated as a pure acrylate, compound and / or blend from the solution, as an aqueous system or as a hot melt from the melt. Use according to claim 1, characterized in that a pressure-sensitive adhesive based on acrylate hotmelt is used. Use according to one of the preceding claims, characterized in that a pressure-sensitive adhesive is used which has a K value of at least 20, in particular greater than 30, measured in a 1% strength by weight solution in toluene at 25 ° C. Use according to one of the preceding claims, characterized in that the adhesive is obtainable by concentrating a solution of such a mass to form a system which can be processed as a hot melt. Use according to one of the preceding claims, characterized in that the solution of the mass contains 5-80% by weight, in particular 30-70% by weight, of solvent. Use according to one of the preceding claims, characterized in that commercially available solvents are used, in particular low-boiling hydrocarbons, ketones, alcohols and / or esters. Use according to one of the preceding claims, characterized in that single-screw, twin-screw or multi-screw extruders with one or in particular two or more degassing units are used. Use according to one of the preceding claims, characterized in that the adhesive can be crosslinked by chemical or thermal treatment, in particular by radiation chemical treatment. Use according to one of the preceding claims, characterized in that the adhesive is admixed with radiation-chemically and / or chemically and / or chemically activatable substances and / or is polymerized into it, in particular photoinitiators, in particular benzoin derivatives. Use according to one of the preceding claims, characterized in that copolymers of (meth) acrylic acid and their esters with 1 to 25 carbon atoms, maleic, fumaric and / or itaconic acid and / or their esters are substituted as self-adhesive compositions
(Meth) acrylamides, maleic anhydride and other vinyl compounds, such as vinyl esters, in particular vinyl acetate, vinyl alcohols and / or vinyl ethers. Use according to one of the preceding claims, characterized in that fabrics, knitted fabrics, fleeces, foils, paper, felts, foams and coextrudates are used as carriers.