WO2021197772A1

WO2021197772A1 - Adhesive tape, in particular cable wrapping tape for wrapping cables in automobiles

Info

Publication number: WO2021197772A1
Application number: PCT/EP2021/055870
Authority: WO
Inventors: Timo Leermann
Original assignee: Certoplast Technische Klebebänder Gmbh
Priority date: 2020-04-01
Filing date: 2021-03-09
Publication date: 2021-10-07
Also published as: CN115362232A; DE202020101775U1

Abstract

The invention relates to an adhesive tape, in particular a cable wrapping tape for wrapping cables in automobiles, comprising a carrier (2, 3) and an adhesive coating (4) on at least one side of the carrier (2, 3), characterized in that the adhesive coating (4) is provided with embedded carbon nanotubes.

Description

Adhesive tape, in particular cable wrapping tape for wrapping cables in automobiles

Description:

The invention relates to an adhesive tape, in particular a cable wrapping tape for wrapping cables in automobiles, with a carrier and with an adhesive coating on at least one side of the carrier.

Adhesive tapes and in particular cable wrapping tapes for wrapping cables in automobiles have to meet very different requirements. In addition to easy processing and the associated hand tearability, resistance to chemicals such as oil and gasoline is typically required. In addition, such adhesive tapes must be able to withstand elevated temperatures, which can be up to 125 ° C. and more. In addition, abrasion resistance and good noise dampening behavior play a role.

In addition to these requirements, there are nowadays other properties that are required of such adhesive tapes and especially cable wrapping tapes. These manifest themselves in particular in the case of hybrid and electric vehicles, for example, in that due to the high currents of sometimes several 100 A flowing in this context at voltages in the range of up to 400 V and in the direction of 800 V, strong magnetic alternating fields arise. These can not only induce interference currents in the on-board electronics, but in principle also represent a possible source of interference for the human body. So far, there are neither relevant standards nor reliable solutions at this point. Rather, an attempt is made to provide at least partial electromagnetic shielding via, for example, shielding metal sheets inside the motor vehicle, which, however, is not sufficient overall. For example, the generic US Pat. No. 4,327,246 deals with an adhesive tape which is helically wound around electrical cables in order to provide electrical shielding. For this purpose, the known adhesive tape has, among other things, an incorporated film layer made of a conductive material such as copper, aluminum or also silver. In fact, one or more film strips are implemented at this point. However, the practical implementation of such an adhesive tape is complex and expensive.

A comparable adhesive tape is presented in WO 03/054438 A1. However, questions about a possible shielding of electromagnetic radiation are not taken into account.

The prior art has proven itself overall when it comes to using adhesive tapes and in particular cable wrapping tapes for wrapping cables in automobiles, with the aid of which the wrapped cables are in particular mechanically protected and assembled. In addition, approaches with US 4,327,256 are already available to implement additional electromagnetic shielding. However, the detailed structure of the known adhesive tape is complicated. In addition, the production costs are high, so that such embodiments have so far not experienced any or only a slight practical implementation. The invention aims to provide a remedy here overall.

The invention is based on the technical problem of further developing such an adhesive tape and in particular cable wrapping tape for wrapping cables in automobiles in such a way that electromagnetic shielding is also available in addition to the general requirements for the area of application is provided, taking into account reduced manufacturing costs compared to the prior art.

To solve this technical problem, a generic adhesive tape and in particular cable wrapping tape for wrapping cables in automobiles within the scope of the invention is characterized in that the adhesive coating is equipped with embedded carbon nanotubes.

According to an advantageous embodiment, the carbon nanotubes are present in the adhesive coating in a concentration of at least 0.01% by weight. The maximum concentration of the carbon nanotubes in the adhesive coating is up to 30% by weight. A concentration of 0.01% by weight to 10% by weight of the carbon nanotubes in the adhesive coating is preferably observed at this point. Very particularly preferred is a grammage of the carbon nanotubes in the adhesive coating in the range from 0.01% by weight to 5% by weight, the information given above relating in each case to the mass of the adhesive coating.

In the prior art according to EP 2079816 B1, there have already been attempts to work with an adhesive tape used as an adhesive packaging tape with a carrier which has carbon nanotubes in at least one of its carrier films. As a result, high modulus values are to be observed in the known packaging tape in the longitudinal direction, for example a certain tension at 10% elongation. In other words, the known teaching directed to an adhesive packaging tape is limited to mechanically upgrading the carrier or a corresponding carrier film with the aid of the carbon nanotubes. In contrast, questions of electromagnetic compatibility or shielding do not play a role. In the context of the invention, however, it has been found that even relatively low concentrations of the carbon nanotubes in the adhesive coating are sufficient to achieve a significant shielding of the electromagnetic radiation. In fact, attenuation of the electromagnetic radiation in the relevant frequency range from approx. 100 MHz to approx. 10 GHz is observed at this point, which is regularly above 5 dB, mostly above even 10 dB and preferably more than 20 dB and more. Electromagnetic radiation attenuations of 30 dB and more are often achieved. The frequency range in question from approx. 100 MHz to approx. 10 GHz is relevant insofar as, for example, the standard DIN EN 50147-1 96 is relevant at this point with regard to shielded attenuation and the test for electromagnetic compatibility (EMC) is based on this. This is evident from the explanations in DE 102017 112603 A1, which are only given by way of example and which deals with a shielded element for electrical or electronic functional elements. The shielded element in question is used in motor vehicles to dissipate electrical charges and / or to dampen electromagnetic fields in accordance with the aforementioned standard.

The carbon nanotubes used according to the invention represent small tubes, the diameter of which is regularly less than 100 nm. A few nanometers are typically observed at this point for the diameter of the carbon nanotubes in question. The term nanotubes also indicates that the length of the tubes exceeds their diameter. At this point, lengths of a few micrometers are typical. As a result, the carbon nanotubes in question are usually available in powder form. As a result, the carbon nanotubes present in powder form can easily become a component of a Represent processing compound for the adhesive coating. As a result, processing is simplified and production costs can also be significantly reduced.

The carbon nanotubes or CNT (carbon nanotube) are usually produced by laser ablation of graphite, by arc discharge between carbon electrodes or in connection with chemical vapor deposition (CVD). The individual carbon nanotubes can be single-walled or multi-walled. Their walls are each made of carbon, with the carbon atoms taking up a honeycomb-like structure with six corners.

In addition to the electromagnetic shielding properties already mentioned, such carbon nanotubes also have outstanding mechanical properties. This is because they are generally equipped with a density in the range from 1.3 g / cm ³ to 1.4 g / cm ³ . In addition, they typically have a tensile strength of 30 GPa for single-walled carbon nanotubes, which can increase up to 63 GPa for a multi-walled embodiment. In comparison, steel has a density of around 7.85 g / cm ³ and has a maximum tensile strength of 2 GPa.

In any case, in this way an adhesive tape is made available within the scope of the invention, which provides a significant shielding of electromagnetic radiation through the carbon nanotubes embedded in the adhesive coating. As a result, any electromagnetic inductions in control devices or other electronic components, in particular in motor vehicles, are prevented or at least weakened and, in addition, any possible health risks for Operators inside the motor vehicle reduced to a minimum. The shielding or attenuation of the electromagnetic radiation mainly comes into play in the relevant frequency range from approx. 100 MHz to approx. 10 Hz, so that the adhesive tapes in question are particularly predestined for use in connection with hybrid vehicles or electric automobiles. This is where the main advantages can be seen.

The processing compound with the powder from the carbon nanotubes dispersed therein for producing the adhesive coating can, for example, be designed as an extrusion compound for applying a hotmelt adhesive as an adhesive coating. In this case, the hotmelt adhesive may be, for example, one based on acrylic type, which is produced according to the invention in powder form from the extrusion compound in question with the embedded carbon nanotubes and applied to the carrier.

To produce the adhesive coating, the processing compound can be applied to the carrier in the form of a hot melt adhesive. At this point, a conventional nozzle application is usually used, so that the hotmelt adhesive or hotmelt adhesive is applied to the carrier as a hotmelt. Alternatively or additionally, however, a contactless adhesive coating is also conceivable in this context. Here, for example, an adhesive is applied to the carrier in the course of a pressureless coating process, such as the so-called “curtain coating process”. A closed adhesive film falls onto the substrate. As a result, a uniformly thick and consequently consistent grammage of the adhesive coating is achieved overall. The same applies in the event that, as an alternative or in addition, the adhesive is applied to the carrier with the aid of a transfer coating. Alternatively, however, the processing compound can also be applied to the carrier in the form of an application solution or dispersion to produce the adhesive coating. In this case, the carbon nanotubes are again dispersed in powder form in the application solution or dispersion and applied to the carrier together with the application solution or dispersion. The application solution can be, for example, a known dispersion-containing and solvent-containing adhesive, for example an acrylate dispersion or the like.

In this case, the application can be carried out by means of a doctor blade or a comparable line application, a roller application or roller application or also in the course of a spray application. In addition to basically water, organic solvents such as alcohols and in particular ethanol, propanol, ethylene glycol, etc. are typically used as possible solvents. Likewise toluene or, for example, ethyl acetate.

In principle, the invention independently also includes the use of rubber compound with embedded carbon nanotubes as an adhesive coating that is additionally crosslinked. The rubber compound may be applied to the carrier as a dispersion, hot melt or polymer melt. The rubber compound is then usually crosslinked with electron beams and / or UV rays. The application of the adhesive coating as a polymer compound and its subsequent crosslinking is of course also possible in principle with adhesives that are not based on rubber compound.

The carbon nanotubes are generally in a concentration of in the processing compound for producing the adhesive coating 0.01% by weight to 30% by weight based on the processing composition. As a result, the desired concentration of carbon nanotubes is also made available overall in the adhesive coating. In addition, the adhesive coating can in principle be a strip coating. Alternatively or additionally, however, the invention also works with a full-surface coating as an adhesive coating.

All variants are possible as conceivable supports in this context, for example film supports, paper supports, felt supports, multilayer supports, etc. A variant in which the support has wholly or partially at least one textile support layer is particularly preferred. Such textile backing layers are particularly suitable for the described area of application as cable wrapping tape for wrapping cables in automobiles because they can be produced inexpensively on the one hand and provide the necessary flexibility in connection with pronounced noise damping and abrasion resistance on the other hand.

Consequently, the carrier advantageously has at least one textile carrier layer in whole or in part. This textile carrier layer can be one made from a woven fabric, a fleece, a knitted fabric, a scrim, a velor individually or in combination. As a further option, the invention provides that the carrier - in addition to the adhesive coating - is also equipped with embedded or applied carbon nanotubes.

This succeeds particularly advantageously in connection with the implementation of a textile carrier layer. This is because this usually uses the plastic fibers from which it is made up. When the plastic fibers are fused, the carbon nanotubes in powder form can again be used Extrusion mass for the production of these textile plastic fibers are added. A non-woven carrier, for example, can be produced from the plastic fibers. In addition, there is the possibility of processing the plastic fibers in a fabric or of realizing and implementing the other variants such as a knitted fabric, a scrim or even a velor individually or in combination for the textile carrier layer. In this case, too, the installation of the carbon nanotubes is particularly easy and inexpensive, because they are added in powder form or as a dispersion to the processing compound or extrusion compound for the production of the plastic fibers or plastic threads, from which the textile carrier layer in question is then made.

The carrier can in principle also be constructed as a multilayer carrier from the textile carrier layer and additionally at least one further layer. This further layer can be a film layer and / or a foam layer. As an alternative to the textile carrier layer, the film layer or the foam layer can also be equipped with the carbon nanotubes. In this case, the carbon nanotubes in powder form are again added to the processing compound or extrusion compound for producing the film layer or foam layer. The processing compound may very generally be a polymer granulate.

As a result, an adhesive tape is made available which is initially particularly predestined for use in or on a motor vehicle and here as a cable wrapping tape for wrapping cables. For this purpose, the known adhesive tape is not only designed to be resistant and typically tearable by hand, but also prevents any rattling noises. Of particular importance is then that property according to the invention, namely to be able to provide a significant attenuation of electromagnetic radiation. This is ensured by the embedded carbon nanotubes.

If at this point the carrier is designed with a textile carrier layer in the form of a fabric or also as a multi-layer carrier, typical abrasion resistance according to standard LV 312 (status 10/2009) at least class B or C can be achieved. This applies in particular to the case that a certain fabric is used as a textile carrier layer or, in this context, weft threads are used that are thicker than the associated warp threads. With all of this, production is particularly easy and inexpensive because the carbon nanotubes are added in powder form to the processing compound for the adhesive coating. This is where the main advantages can be seen.

The invention is explained in more detail below with the aid of a drawing showing only one exemplary embodiment; show it:

Fig. 1 shows the adhesive tape used according to the invention schematically in

Longitudinal section,

2A and 2B show the adhesive tape in connection with the wrapping and bundling of cables as well

3 shows the attenuation achieved in relation to electromagnetic

Radiation in the frequency range between 100 MHz and In the figures, an adhesive tape for electrical cables 1 is shown. According to the exemplary embodiment and not by way of limitation, the electrical cables 1 are cables 1 as components of cable harnesses in automobiles. The adhesive tape in question can in principle be wrapped around the cable 1 as a lengthwise envelope, as is shown in principle in FIG. 2B. As a rule, however, the procedure is such that the adhesive tape is looped helically around the cable 1, as can be seen from FIG. 2A.

As evidenced by the sectional view in FIG. 1, the adhesive tape has a carrier 2, 3 which, according to the exemplary embodiment, has a multilayer design. In fact, the carrier 2, 3 completely or partially has at least one textile carrier layer 2. The textile carrier layer 2 is a fabric which is made up of warp threads 2a running in the longitudinal direction and weft threads 2b running transversely thereto.

In addition to the textile carrier layer 2, the known carrier 2, 3 according to the exemplary embodiment is also equipped with a film layer 3. The film layer 3 is also equipped with an adhesive coating 4 on its outwardly facing surface. The adhesive layer 4 is applied over the entire surface or over part of the surface of the film layer 3. In principle, however, the adhesive layer 4 can also be applied directly to the textile carrier layer 2.

Instead of the fabric shown as the textile carrier layer 2, a fleece, a knitted fabric, a scrim or even a velor can be used individually or in combination at this point. In addition, the invention also includes variants such that the textile carrier layer 2 consists of two interconnected fabrics, one fabric and a non-woven fabric, a woven fabric and a velor, etc. is constructed. However, this is not shown in detail.

In the context of the invention, the adhesive coating 4 is equipped with embedded carbon nanotubes. The carbon nanotubes are present in the adhesive coating 4 in a concentration of generally more than 0.01% by weight. At the maximum concentration of the carbon nanotubes is in the adhesive coating 430 wt .-%, each based on the mass of the adhesive coating 4. According to the embodiment, the adhesive coating 4 having a basis weight of 150 g / m ² on the films layer 3 applied.

In the exemplary embodiment, the carbon nanotubes are in powder form and form part of the processing compound for the adhesive coating 4. The processing compound is specifically an extrusion compound with the aid of which the adhesive coating 4 is applied to the carrier 2, 3. According to the exemplary embodiment, an extrusion compound for the application of a hot melt adhesive is used as an adhesive coating 4 at this point, which of course only applies as an example and is not to be understood as limiting.

The sectional illustration in FIG. 1 shows that the warp threads 2a and the weft threads 2b of the textile carrier layer 2 have the same thread count. In principle, however, it would also be possible to work with weft threads 2b which are made significantly thicker than the warp threads 2a. As a result, the abrasion resistance of the adhesive tape can be increased if necessary. The carrier 2, 3 can - in addition to the adhesive coating 4 - also be equipped with embedded carbon nanotubes to implement electromagnetic shielding. However, that's only as Understand option. Because, as a rule, it is sufficient if only the adhesive coating 4 of the illustrated adhesive tape is equipped with the embedded carbon nanotubes. With reference to Fig. 3 you can now understand the effect achieved in terms of shielding against electromagnetic radiation using the fiction, contemporary adhesive tape. In fact, FIG. 3 shows the shielding effect of the adhesive coating 4 alone. As already explained above, the adhesive coating 4 has a weight per unit area of 150 g / m ^2. This results in different grammages or concentrations of the carbon nanotubes, which are reflected in the three curves shown in FIG.

In fact, the solid curve corresponds to a concentration of 4.1% by weight of the carbon nanotubes in the adhesive coating 4, while the other and dashed variant has a grammage of 7.5% by weight based on the mass of the adhesive coating 4 is equipped. The last; The curve shown in dash-dotted lines relates to a grammage or concentration of the carbon nanotubes of 10.5% by weight.

It can be seen that even at the lowest concentration of 4.1% by weight of the carbon nanotubes in the adhesive coating 4, an attenuation of the electromagnetic radiation in the relevant frequency range from approx. 100 MHz to approx. 10 GHz of consistently more than 30 dB will. These

With the increased concentration of the carbon nanotubes in the third example, attenuation can be increased to values of almost 50 dB or even more, taking into account 10.5% by weight. This makes it clear that with increasing concentration of carbon nanotubes in the

Adhesive coating 4 increases the damping effect against electromagnetic radiation in the observed frequency range of 100 MHz-10 GHz.

Claims

Patent claims:

1. Adhesive tape, in particular cable wrapping tape for wrapping cables in automobiles, with a carrier (2, 3), and with an adhesive coating (4) on at least one side of the carrier (2, 3), characterized in that the adhesive coating (4) with embedded carbon nanotubes is equipped.

2. Adhesive tape according to claim 1, characterized in that the carbon nanotubes in the adhesive coating (4) in a concentration of 0.01 wt .-% to 30 wt .-%, preferably from 0.01 wt .-% to 10 % By weight, particularly preferably from 0.01% by weight to 5% by weight, based in each case on the mass of the adhesive coating (4).

3. Adhesive tape according to claim 1 or 2, characterized in that the carbon nanotubes are in powder form and represent a component of a processing compound for the adhesive coating (4).

4. Adhesive tape according to claim 3, characterized in that the processing compound for producing the adhesive coating (4) is applied in the form of a hot melt adhesive.

5. Adhesive tape according to one of claims 1 to 4, characterized in that an adhesive is applied to the carrier (2, 3) via a nozzle and / or a curtain coating process and / or a transfer coating.

6. Adhesive tape according to one of claims 3 to 5, characterized in that the processing compound for producing the adhesive coating (4) is applied in the form of a dispersion or solution.

7. Adhesive tape according to claim 6, characterized in that the application of the dispersion or solution is carried out by means of a doctor blade or a comparable line application, a roller application or roller application or also in the course of a spray application.

8. Adhesive tape according to one of claims 1 to 7, characterized in that the carbon nanotubes are present in the processing composition in a concentration of 0.01% by weight to 30% by weight.

9. Adhesive tape according to one of claims 1 to 8, characterized in that the adhesive coating (4) is designed as a strip coating.

10. Adhesive tape according to one of claims 1 to 9, characterized in that the adhesive coating (4) is designed as a full-surface coating.

11. Adhesive tape according to one of claims 1 to 10, characterized in that the carrier (2, 3) has wholly or partially at least one textile carrier layer (2).

12. Adhesive tape according to claim 11, characterized in that the textile carrier layer (2) consists of a woven fabric, a fleece, a knitted fabric, a scrim, a velor individually or in combinations.

13. Adhesive tape according to one of claims 1 to 12, characterized in that the carrier (2, 3) is equipped with embedded or applied carbon nanotubes.

14. Adhesive tape according to one of claims 1 to 13, characterized in that the carrier (2, 3) is designed as a multi-layer carrier from the textile carrier layer (2) and additionally at least one further layer (3).

15. Adhesive tape according to claim 14, characterized in that the further

Layer (3) is designed as a film layer (3) and / or foam layer.