EP1453614B1 - Coating method - Google Patents

Description

The invention relates to a method for the production of web-shaped, at least two-layer products, in particular adhesive tapes with a carrier material, to which an adhesive is applied.

For a long time it has been worked to produce tapes without the use of solvents or at least to make the coating process and the subsequent steps solvent-free. Corresponding products with adhesive layers based on synthetic rubbers are known. However, these products only cover the lower performance range of adhesive tapes.

Solvent-free acrylate-based adhesives have also been available for some years and can be further processed as a hot-melt adhesive for adhesive tapes. However, these usually do not achieve the shear strengths such as acrylate compositions which are coated in solvent dissolved. A major reason for this is that the viscosity of the masses during processing must not be too high, otherwise the melting and coating on a carrier from an economic point of view is too expensive. The viscosity is essentially determined by the molecular length. Shorter chain molecules, however, cause inferior shear strengths. Even with a crosslinking of the adhesive after the coating, only a limited improvement is possible.

In natural rubber adhesive systems, melting can be avoided if the components of the composition can be mixed without solvent and if the hot mass is fed directly to a coating system. Come as mixing units for example extruder in question. When mixing, the rubber may, however, be broken down only slightly, otherwise the product properties are impaired.

For acrylate systems, remelting can be avoided by removing solvent or water in-line for coating in solvents or in water polymerized masses. For example, solvent or water can be removed via vacuum zones in a suitable extruder.

For the coating of highly viscous masses slot slit nozzles are suitable. It turns out that they are also suitable for high-viscosity adhesive compositions as described above. However, from a relatively low line speed, air bubbles are trapped between the adhesive and the substrate to be coated, which is typically coated on a platen roller.

To reduce the blistering for the above task blowing nozzles, suction nozzles and so-called vacuum boxes are recommended and offered on the market. With their help, the pressure force of the mass is to be increased against the substrate.

From the film production (for example EP 0 920 973 A2) are wire, knife and needle electrodes, which are arranged transversely to the web, known, with which electrical charges are placed on the mass to be launched. As a result, the mass is pressed by electrostatic forces against a metal roller. Furthermore, combinations of electrostatic forces and forces by air movement are used (EP 0 707 940 A2).

In the literature, complex solutions are specified for the above-described coating of substrates, in which the substrate is charged before laying on the cooling roller in multi-stage preliminary processes, partially discharged by heating and cooled to finally obtain a uniform charging of the substrate on the lay-up roll (for example EP 0 299 492 A2).

However, the maximum amount of charge on the substrate here is relatively low, since it is already reduced when leaving the charging roller until no longer occurs due to the resulting charge density of the electric field strength ionization of the air.

In film production (see, for example, US Pat. No. 4,997,600 A1), roller insulation is known in which electrical charges are applied to the insulator layer before the film is laid down, in order to increase the contact pressure when the film is placed on the roller.
If no charges are applied to the insulated roller, then electrostatic pressure forces are greatly weakened when placed with increasing thickness of the insulator layer. With the requisite insulator thicknesses required for the ceramic coatings specified herein for adequate high voltage strength, achievable bubble-free coating speeds are drastically reduced.

• auf eine rotierende Walze das Haftklebesystem in einer oder mehreren Lagen mittels eines Kdebstoffauftragswerks aufgebracht wird,
• das auf der Walze befindliche Haftklebesystem in einer Bestrahlungsvorfichtung durch energiereiche Strahlung, und zwar mit Hilfe von Elektronenstrahlen (ES), UV-oder IR-Strahlen, vernetzt wird und
• an die Walze das Substrat herangeführt wird, so daß das Haftklebesystem von der Walze auf das Substrat transferiert wird und gegebenenfalls aufgerollt wird.

DE 199 05 935 A1 discloses a process for producing a coating of solvent-free pressure-sensitive adhesive systems on in particular release-coated substrates, wherein

• on a rotating roller, the pressure-sensitive adhesive system is applied in one or more layers by means of a Kdebstoffauftragswerks,
• the pressure-sensitive adhesive system on the roll is crosslinked in an irradiation preform by high-energy radiation, with the aid of electron beams (ES), UV or IR rays, and
• the substrate is brought to the roller, so that the pressure-sensitive adhesive system is transferred from the roller to the substrate and optionally rolled up.

Typical irradiation devices, which are used in the embodiment of the method shown there, are linear cathode systems, scanner systems or multi-longitudinal cathode systems, if it is electron beam accelerator.
The acceleration voltages are in the range between 40 kV and 350 kV, preferably 80 kV to 300 kV. The dose rates range from 5 to 150 kGy, especially 20 to 90 kGy.
As UV crosslinking systems, it is possible, in particular, to use two medium-pressure mercury lamps each with a power of 120 W / cm or a medium-pressure mercury lamp with a power of 240 W / cm. As cans, preferably 10 to 300 mJ / cm ^{2 are} set.

The leading of the substrate is done in particular via a second roller. The substrates used are papers, films, non-wovens and release-coated materials such as release papers, films and the like.
The second roller, also referred to as the application roller, may be provided with a rubber coating and is preferably pressed against the roller with a line pressure of 50 to 500 N / mm, in particular 100 to 200 N / mm. The application roller preferably has a Shore hardness (A) of 40 to 100, in particular a Shore hardness of 60 to 80 shore (A).
The substrate is preferably fed to the roller so that the speed of the roller surface coincides with that of the substrate. However, if a reduction in thickness is desired with the decrease of the adhesive film, the substrate may also have a higher speed.

In an advantageous embodiment, the roller is a steel roller, a chromium-plated steel roller, a rubber roller or a silicone rubber roller and / or the roller is made of elastic material. Furthermore, the roller may have a smooth or a slightly textured surface.
The smooth roller may preferably have a chromium layer. Optionally, the chrome-plated steel roller can have a highly polished surface with a roughness R _z <0.02 μm.
However, the coating roller may also be rubberized, preferably with a rubber hardness of 40 to 100 shore (A), in particular with a hardness of 60 to 80 shore (A). Of the Roll cover can be made according to the prior art of EPDM, Viton or silicone rubber or other elastic materials.

It is further found to be advantageous if the roll is heatable, preferably in a range of -10 ° C to 200 ° C, in particular from 2 ° C to 50 ° C.

If, for the production of adhesive tapes, one or both sides coated with very thin layers antiadhesive substrates with an adhesive, the release effect of the substrate is particularly affected against acrylate when the application of the adhesive is supported electrostatically with high voltage electrodes.

US Pat. No. 4,748,043 A discloses a process for the production of web-shaped, at least two-layer products in which a mass emerging from an application device is applied as a layer to electrostatic charges on a web-shaped substrate. The substrate is not guided on a transport device, there is no transport device.
Under the substrate there is a metallic plate which is accordingly not provided with an electrically insulating coating.

From US Pat. No. 5,032,422 A, a process for the production of web-shaped, at least two-layered products is known in which a mass emerging from an application device is applied as a layer by applying electrostatic charges to a metallic plate. This plate is guided on a transport device. The applicator has no electrically insulating coating.

US Pat. No. 6,127,003 A discloses a process for the production of sheet-like products, at least two-layered products, in which a composition emerging from an application device is applied as a layer. The electrostatic charges are applied to the uncoated side of the substrate, not the mass to be coated.

• keine Blasen zwischen der Masseschicht und dem Substrat eingeschlossen werden,
• keine Eigenschaften des herzustellenden Produktes qualitätsbestimmend beeinträchtigt werden,
• keine Gefährdungen für das Bedienungspersonal entstehen.

The object of the invention is to enable the coating of highly viscous masses, as used for the production of adhesive tapes or similar products, under the preferred use of a slot die at sufficiently high web speeds on a substrate.
It should

• no bubbles are trapped between the ground layer and the substrate,
• no properties of the product to be produced are impaired in terms of quality,
• No danger to the operating personnel.

This problem is solved by a method as laid down in the main claim. The subclaims describe advantageous embodiments of the method.

Accordingly, the invention relates to a process for the production of web-like, at least two-layer products, in which an emerging from an applicator mass is applied as a layer with application of electrostatic charges on a web-shaped substrate which is guided on a transport device, so that on the surface of the Transporter set counter-charges and from the resulting field a force on the mass plus substrate acts, which presses both layers on the transport device, so that no air bubbles are trapped between the ground layer and the substrate, and in which and in which the mass-coated substrate is electrostatically neutralized before leaving the transport device, wherein the transport device is provided to reduce damage with an electrically insulating coating and wherein the mass is an adhesive.

In a first preferred embodiment of the method, the application device is designed as a nozzle, in particular slot die, two- or multi-channel nozzle or adapter nozzle.
The transport device is preferably coated without contact with the material emerging from the nozzle. The distance of the nozzle to the transport device may preferably be 0.01 to 60 mm, in particular 1 to 30 mm.

Further preferably, the transport device is configured as a lay-on roller, which is further embodied in particular grounded and / or tempered, and preferably in a range of -10 ° C to 200 ° C, most preferably in a range of 0 ° C to 180 ° C. , in particular from 2 ° C to 50 ° C.

In order to be able to provide the composition with the charge according to the invention, the composition can be electrostatically charged by means of at least one charging electrode, referred to below as the deposition electrode, which is located above the transport device, preferably the laying roller, in the region of the contact line of the mass layer. With the help of the charges, the layer is pressed onto the substrate.
Charges, for example electrons, are applied to the ground on one side with the lay-on electrode. On the surface of the transport device, preferably lay-on roller, counter-charges are immediately established. From the resulting field acts a force on the mass plus substrate, which presses both layers on the transport device, preferably lay-on roll.

Furthermore, it represents an excellent embodiment of the inventive concept, when the substrate coated with the mass is electrostatically neutralized by means of at least one counter-charging electrode before leaving the transport device, preferably lay-up roller, wherein the counter-charging electrode in particular on the transport device, preferably lay-on roller, in the area is located between the support layer of the ground layer and the withdrawal line of the coated substrate. Thus, electrostatic discharges, as a result of the application of charges by the lay-on electrode, can be reversed by the application of reverse charges Polarity and appropriate strength, even before leaving the coated substrate of the preferred application roller, can be avoided.

For fine adjustment, it is also advantageous to apply an active discharge device over the release line of the coated substrate from the preferred layup roll to compensate for variations in the process over time and width of the web.

Preferably, the counterelectrode electrode is in the form of a "wire", "knife" and / or "needle electrode" arranged across the web.

Without adequate neutralization of the electrical charges applied to the web by the lay-on electrode (s), corona discharge may occur between the lay-up roll and the underside of the substrate, adversely affecting particularly anti-adhesive properties of the substrate.
In addition, the corona discharge transports charges of opposite polarity as on the coating side to the underside of the web. If such a web is subsequently neutralized with conventional active or passive discharge devices, the measurable electric field is eliminated, but thereafter very large, equally high charges of opposite polarity are present on the two sides. If the electrical conductivity of the layers between charges is low, uncontrollable discharges may occur in wound bales.

Then, in order to stress the substrate slightly, the substrate should be placed with a pressure roller on the transport device, preferably lay-up roller, and / or removed with a take-off roller from the transport device, preferably lay-up roller.
It is also advantageous to select a conductive elastic coating for the preferred pressure roller with which the substrate is placed on the preferably selected application roller. If a conductive coating can not be used for reasons of process technology, it is advantageous to discharge the roll shell electrostatically in a region in which it is not covered by the substrate. Otherwise, the roller surface can absorb more electrical charges with each revolution until uncontrolled discharge phenomena occur.

Furthermore, it is advantageous to arrange a diaphragm of electrically insulating material in the web running direction in front of the laying electrode, whereby the ion-enriched space in the region of the laying electrode is limited to the nozzle side. It is also advantageous to install a grounded, electrically conductive sheet on the side of the panel facing away from the lay-up electrode. With the aperture, a corona discharge before the lay-up line can be significantly reduced by the mass layer on the substrate.

Also advantageous is an arrangement in which not only one needle electrode is used as lay-on electrode, but two in the web direction directly behind each other and in which the two electrodes are laterally offset by half a needle spacing, whereby the ability of the needle electrodes to high charging currents with a relatively uniform charge distribution is paired. It has proven to be advantageous to occupy the front electrode with a smaller high voltage than the rear.

In a further preferred embodiment of the invention, the substrate is electrostatically neutralized before coating.

In a further preferred variant of the method according to the invention, the mass is crosslinked or polymerized on the substrate before leaving the transport device, preferably lay-up roller, in particular by means of electron beams, UV rays, visible light or thermal or even a combination of said methods.

In a further preferred embodiment of the method, the thickness of the coating is thinner than 300 .mu.m, especially between 20 and 200 .mu.m very particularly between 20 and 120 .mu.m thick and / or deviates on the entire substrate-contacting surface of the transport device preferably not more than ± 20% of Mean value, in particular not more than ± 5%.

Furthermore, it is very advantageous if the coating has a low roughness and / or anti-adhesive properties.

It is particularly advantageous to electrostatically neutralize the coating in a region in which it is not covered by the substrate, before it is covered by the substrate. Otherwise it can absorb more electrical charges with each revolution until uncontrolled discharge phenomena occur. But even minor uncontrolled charges, especially if they are uneven, have a negative influence on the blistering between coating and substrate.

In an excellent embodiment, the coating consists of polyester, Teflon, Kapton, silicone rubber, polypropylene, cast resin or other materials with sufficient high-voltage strength at low layer thickness.

For example, as a cover, a shrink tube, which is pulled and shrunk on the transport device, in particular a lay-up roll, can be used.
A coated with an insulator, electrically conductive sleeve sleeve, which is pulled over the on the transport device, in particular lay-on roller, is in an excellent manner.

The coating is applied in a preferred variant of the method in excess, is optionally cured, further this is subsequently removed to a desired very constant layer thickness and polished the final for a low roughness.

By way of example, as possible embodiments of the coating, different-thickness PET films may be mentioned, furthermore casting resin applications, preferably with thicknesses between 20 μm and 300 μm, and in particular with thicknesses between 20 μm and 120 μm.

A further preferred variant is an electrically conductive conveyor belt coated with an electrical insulator, on which the substrate is guided over a laying roller for coating, the coating preferably having thicknesses between 20 μm and 300 μm and in particular thicknesses between 20 μm and 120 μm ,

Also, a thin conveyor belt made of an electrical insulator, preferably with thicknesses between 20 microns and 300 microns and in particular with thicknesses between 20 microns and 120 microns, on which the substrate is passed over a coating roller for coating, represents preferred variant.

A further preferred variant is a modification in which an auxiliary film, which is brought after unwinding of a bale between the electric conductive transport device and the substrate, after the stripping of the coated substrate from the auxiliary film is rewound into a bale.

The process can be used excellently in applications in which the substrate is a release liner for an adhesive tape.
In this case can also be used as a mass of acrylate, natural rubber, synthetic rubber or EVA adhesives.

The process can be used equally well in applications where the substrate is a precursor consisting of release liner, adhesive and carrier for a double-sided adhesive tape

Furthermore, it is found that the tendency for blistering between the mass and the substrate increases when the substrate has charged uncontrollably before being placed on the lay-up roll. It is also problematic if electrostatic discharge devices are not mounted on the side of the web on which charges can be taken by separation processes. Even in this case, although no electric field is measured from the outside, but nevertheless located on both sides of the web equally strong electrical charges with opposite polarity. The height of these double charges typically varies in the direction of the web and also across the web. These undefined double charges reduce the maximum web speed that can be safely traversed in a production process.

In an advantageous embodiment, discharge devices are always mounted on the side on which charges arise by separation processes. In the case of electrostatically difficult substrates, it may be advantageous in extreme cases to install suitable discharge devices behind each deflection roller on the contact side and already in the winding nip during unwinding.

Furthermore, it is advantageous to drive the delivered bales electrostatically controlled with the substrate already in the pre-process, or to choose the intermediate storage time due to sufficient electrical residual conductivities large enough for the confluence of double charges. The time required can also be shortened by storage at elevated temperatures.

It is particularly advantageous to provide in the web running direction between the applicator and the lay-on electrode a diaphragm of electrically insulating material, whereby the space filled with ions in the region of the laying electrode of the applicator, in particular nozzle, the transport device, in particular lay-on roller, and the aperture is limited.

Also, the coating may consist of one or more views and / or the substrate of one or more layers, wherein it is advantageous to produce multi-layer coatings with multi-channel or adapter nozzles

It is also very advantageous if, with the aid of adapters in the case of a single-channel nozzle or with a three-channel nozzle, a coating consisting of a first adhesive, a carrier and a second adhesive is discharged and the substrate is a release liner.

For the skilled person unexpectedly, the inventive method provides a solution to the tasks. Thus, a coating with a slot die on a substrate at sufficiently high web speeds is possible without bubbles between the mass layer and the substrate arise without further properties of the product to be produced, especially release properties of release liners, quality affecting and without any special hazards for the operating personnel.

Surprisingly, it has been found that bubbles are formed between the bulk layer and the substrate particularly when there is air between the substrate and the lay-up roll. With bubble-free application of the substrate to the lay-up roll could be coated with a higher line speed, without causing blistering. The coating image is much smoother than one Coating in which the substrate on the lay-up roll was not bubble-free during the manufacturing process.

Further, it can unexpectedly be found that blistering between the bulk layer and the substrate is greatly reduced when electrostatic neutralization of the substrate occurs in the web area prior to the lay-up roll, most preferably on the side where charge accumulation occurs due to charge separation processes ,

Further preferably, the substrate located on the transport device can be crosslinked by means of the irradiation device by high-energy radiation, namely with the aid of electron beams (ES), UV or IR rays, between the lay-on electrode and the discharge electrode. This is particularly advantageous when the substrate is an adhesive.

Typical irradiation devices which are used in the embodiment of the method according to the invention are linear cathode systems, scanner systems or multi-longitudinal cathode systems, if it concerns electron beam accelerators.
The acceleration voltages are preferably in the range between 40 kV and 500 kV, in particular between 80 kV and 300 kV. The dose rates range from 5 to 150 kGy, especially 15 to 90 kGy.
As UV crosslinking systems, in particular one or more medium-pressure mercury lamps with a power of up to 240 W / cm per emitter can be used. As cans, preferably 10 to 300 mJ / cm ^{2 are} set.

For crosslinking or polymerization with visible light in particular halogen lamps can be used.

As substrates, release liners with anti-adhesive coatings on which adhesives have only a slight adhesion can also be used. The support materials of release linem are typically paper or plastics, such as PET, PP or PE. The plastics used generally have good electrical insulation properties and high breakdown electric field strengths.

For papers, on the other hand, the electrical properties are largely determined by the thin anti-adhesive coating, but also by the impregnation and the moisture content. When applying the compound with the aid of electrostatic charging, the electrical properties of the applied mass are of greater importance. Although electrical insulators are mostly used as masses, they often already have such a high residual conductivity at typical coating temperatures of 100 ° C. and more that some of the charges applied flow through the mass and the paper used as a release liner into the lay-up roll before leave the roller. Since virtually all charges are still on the mass layer at the laying line with not too high electrical conductivity, nevertheless sufficiently high pressure forces for a bubble-free coating can be achieved. In the subsequent electrical neutralization by the application of countercharges must, however, note that already a portion of the charges has drained. At low line speeds, the time available to drain the charges increases, and proportionally more charges flow before reaching the detachment line. The optimum amount of countercharges is therefore dependent on the web speed.

For economic reasons, but also for procedural reasons, as thin as possible release coatings are used for release liners. Often also so-called "Unterdeckende coatings" are used. By this is meant that the carrier is not 100% covered by the release coating. It has been found that with such release liners, a neutralization of the coated substrate must be carried out much more accurately than, for example, in PET or PP films with completely covering silicone coatings of 1.5 g / m ² and more.

For double-sided tapes, a distinction is made between the open and the covered side of the release liner. The covered side of the release liner, after unwinding from the roll, is covered with the composite of the first adhesive layer, backing and second adhesive layer. For a trouble-free further processing after the coating to the application, the release forces of the adhesive on the open should be less than or equal to, at least not significantly greater than the separation forces be on the covered page, otherwise the reorientation of the release liner to the other side may occur.

There are also graded release liners available. With them you can ensure that the covered side has significantly higher separation forces.
In particular, in non-graded Reiease Linem damage to the open side in the production of a double-sided adhesive tape may be relatively low, if you want to avoid replacement of an undamaged release liner.

For the production of double-sided adhesive tapes, the substrate may also consist of the precursor from the first operation, namely a release liner, an adhesive layer and the carrier.

As a substrate or carrier material, it is also possible to use all known textile carriers, such as woven, knitted or nonwoven fabrics, "nonwoven" being understood to mean at least textile fabrics according to EN 29092 (1988) and stitchbonded nonwovens and similar systems.
Also, lamination fabrics and knitted fabrics can be used.
Such spacer fabrics are disclosed in EP 0 071 212 B1. Spacer fabrics are mat-shaped laminates with a cover layer of a fibrous or filament nonwoven fabric, a backing layer and individual layers or tufts of retaining fibers present between these layers, which are needled through the particle layer distributed over the surface of the laminate body and interconnect the cover layer and the backing layer. As an additional but not required feature, according to EP 0 071 212 B1 particles of inert rock particles, such as, for example, sand, gravel or the like, are present in the holding fibers.
The holding fibers needled through the particle layer keep the cover layer and the underlayer spaced apart and are bonded to the cover layer and the underlayer.
Spacer fabric or knitted fabric are described inter alia in two articles, namely an article from the trade journal "kettenwirk-praxis 3/93", 1993, pages 59 to 63 "Raschelgewirkte spacer"
and an article from the trade magazine "kettenwirk-praxis 1/94", 1994, pages 73 to 76 "Raschelgewirkte spacer"
the contents of which are hereby incorporated by reference and whose contents become part of this disclosure and invention.

Knitted fabrics are fabrics made from one or more threads or thread systems by stitching (thread grinding), in contrast to woven fabrics (fabrics), in which the surface is made by crossing two thread systems (warp and weft threads) and nonwovens (fiber composites), in which a loose batt is solidified by heat, needling, sewing or by water jets.

Knitted fabrics can be divided into knitted fabrics in which the yarns travel transversely through the textile and into knits in which the yarns run longitudinally through the textile. Due to their mesh structure, knitwear is in principle yielding, supple textiles because the meshes can stretch in length and width and endeavor to return to their original position. They are very durable with high quality material.

As nonwovens are particularly solid staple fiber webs, but also filament, meltblown and spun nonwovens in question, which are usually additionally solidify. As possible solidification methods for nonwovens mechanical, thermal and chemical solidification are known. If, in the case of mechanical consolidation, the fibers are held together purely mechanically by swirling of the individual fibers, by intermeshing fiber bundles or by sewing in additional threads, thermal or chemical methods can be used to bond adhesive (with binder) or cohesive (binder-free) fiber-fiber Achieve bonds. With suitable formulation and process control, these can be limited exclusively or at least predominantly to fiber nodes, so that a stable, three-dimensional network is formed while maintaining the loose, open structure in the nonwoven.

Nonwovens have proven to be particularly advantageous, which are solidified in particular by overmilling with separate threads or by intermeshing.

Such solidified nonwovens are produced, for example, on stitchbonding machines of the "Malivlies" type from Karl Meyer, formerly Malimo, and can be obtained, inter alia, from the companies Naue Fasertechnik and Techtex GmbH. A Malivlies is through characterized in that a cross-fiber fleece is solidified by the formation of stitches of fibers of the fleece.
As a carrier, a nonwoven type Kunitvlies or Multiknitvlies can also be used. A Kunitvlies is characterized in that it results from the processing of a longitudinally oriented nonwoven fabric to a fabric having on one side mesh and on the other mesh webs or pile fiber pleats, but has neither threads nor prefabricated fabrics. Also, such a nonwoven fabric has been produced for example for some time on stitchbonding 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 Multiknitvlies is characterized over the Kunitvlies characterized in that the fleece by the piercing both sides with needles undergoes solidification both on the top and on the bottom.
Finally, sewing nonwovens are suitable as a precursor to form an adhesive tape. A stitchbonded web is formed from a nonwoven material having a plurality of seams running parallel to one another. These seams are created by sewing or stitching of continuous textile threads. For this type of nonwoven stitching machines of the type "Maliwatt" the company Karl Mayer, formerly Malimo, known.

Also particularly advantageous is a staple fiber fleece which is preconsolidated by mechanical processing in the first step or which is a wet fleece which has been hydrodynamically laid, wherein between 2% and 50% of the fibers of the fleece are melt fibers, in particular between 5% and 40% of the fibers of the fleece.
Such a nonwoven fabric is characterized in that the fibers are wet or, for example, a staple fiber nonwoven fabric is preconsolidated by the formation of loops of fibers of the nonwoven or by needling, Vemähung or air and / or water jet machining.
In a second step, the heat-setting takes place, wherein the strength of the nonwoven fabric is further increased by the melting or melting of the melt fibers.
The solidification of the nonwoven backing can also be achieved without binders, for example by hot stamping with structured rolls, wherein properties such as strength, thickness, density, flexibility, etc. are determined by way of pressure, temperature, residence time and the embossing geometry. can be controlled.

For the use of nonwovens, the adhesive bonding of mechanically pre-consolidated or wet-laid nonwovens is of particular interest, and this can be achieved by addition of binder in solid, liquid, foamed or pasty form. Basic forms of administration are variously possible, for example solid binders as powders for trickling, as a foil or as a mesh or in the form of binding fibers. Liquid binders are dissolved in water or organic solvents or can be applied as a dispersion. Bonding dispersions are predominantly selected for adhesive bonding: thermosetting plastics in the form of phenolic or melamine resin dispersions, elastomers as dispersions of natural or synthetic rubbers or mostly dispersions of thermoplastics such as acrylates, vinyl acetates, polyurethanes, styrene-butadiene systems, PVC and the like. and their copolymers. Normally these are anionic or nonionogenically stabilized dispersions, but in special cases cationic dispersions may also be advantageous.

The type of binder application can be carried out according to the prior art and can be read, for example, in standard works of the coating or nonwoven technology such as "nonwovens" (Georg Thieme Verlag, Stuttgart, 1982) or "Textiltechnik-Nonwoven Production" (Employer Group Gesamttextil, Eschborn, 1996).

For mechanically pre-bonded nonwovens, which already have sufficient bond strength, the one-sided spray application of a binder is available in order to change surface properties in a targeted manner.
In addition to the economical handling of the binder, the energy requirement for drying is also significantly reduced in such an operation. Since no nip rolls are required and the dispersions remain predominantly in the upper region of the nonwoven fabric, undesirable hardening and stiffening of the nonwoven fabric can be largely prevented.
For adequate adhesive bonding of the nonwoven backing, it is generally necessary to add binders of the order of 1% to 50%, in particular 3% to 20%, based on the weight of the nonwoven fabric.

The addition of the binder can be carried out already during the nonwoven production, during the mechanical pre-consolidation or else in a separate process step, wherein this can be carried out in-line or off-line. After the binder addition, it is necessary to temporarily form the binder in a state where it becomes adhesive and adhesive connecting the fibers - this can be achieved during drying, for example, of dispersions, but also by heating, with further variations being possible via surface or partial pressure application. The activation of the binder can be done in known drying channels, with a suitable choice of binder but also by means of infrared radiation, UV radiation, ultrasound, high-frequency radiation or the like. For the later end use, it is useful, but not mandatory, that the binder has lost its stickiness after the end of the nonwoven manufacturing process. It is advantageous that volatile components such as fiber excipients are removed by thermal treatment and thus a nonwoven fabric with favorable Foggingwerten, so that when using a fogging adhesive adhesive tape can be produced with particularly favorable Foggingwerten.

Another special form of adhesive bonding is that activation of the binder occurs by solubilization or swelling. In principle, the fibers themselves or blended special fibers can take over the function of the binder here. However, since for most polymeric fibers such solvents are environmentally problematic or problematic in their handling, this method is rarely used.

As starting materials for the textile carrier in particular polyester, polypropylene, viscose or cotton fibers are provided. However, the choice is not limited to the materials mentioned, but it can, recognizing the skilled person without having to be inventive, a variety of other fibers for the production of the web can be used.

In particular, laminates and nets, but also films (for example a polyolefin from the group of polyethylenes (for example HDPE, LDPE, MDPE, LLDPE, VLLDPE, copolymers of ethylene with polar comonomers) and / or the group of polypropylenes are also used as support materials (for example, polypropylene homopolymers, polypropylene random copolymers or polypropylene block copolymers), mono- or biaxially oriented polypropylene, polyester, PVC, PET, polystyrene, polyamide or polyimide), foams, foam, for example of polyethylene and polyurethane, Foamed films and creped and uncreped papers. Furthermore, these materials can be pre- or post-treated. Common pretreatments Corona irradiation, impregnation, coating, painting and hydrophobing; Common aftertreatments include calendering, tempering, laminating, stamping and covering.

A low flammability of the carrier material and the entire adhesive tape can be achieved by adding flame retardants to the carrier and / or the adhesive. These may be bromoorganic compounds, if necessary with synergists such as antimony trioxide, but in view of the freedom from halogens of the adhesive, red phosphorus, organophosphorus, mineral or intumescent compounds such as ammonium polyphosphate alone or in combination with synergists are preferably used.

As adhesives substantially all known adhesives can be used with sufficiently high bond strength on the primer to be packaged.
The adhesive of the adhesive tape may consist of an adhesive based on solvent-containing natural rubber and acrylate adhesives. Adhesives based on acrylate dispersions are preferred, adhesives based on styrene-isoprene-styrene block copolymers being particularly preferred. These adhesive technologies are well known and used in the tape industry.

The application rate of the adhesive to the carrier material is preferably 15 to 60 g / qm. In a further preferred embodiment, the layer application of 20 to 30 g / qm is set.

The adhesive tapes can be produced by known processes. An overview of common manufacturing processes can be found, for example, in "Coating Equipment", Donatas Satas in Handbook of Pressure Sensitive Adhesive Technology, second edition, edited by Donatas Satas, Van Nostrand Reinhold New York pp. 767-808. The known methods for drying and cutting the adhesive tapes can also be found in the Handbook of Pressure Sensitive Adhesive Technology, pages 809-874.

An adhesive which is suitable on acrylate hotmelt basis, which has a K value of at least 20, in particular greater than 30 (measured in each case in 1 wt .-% solution in toluene, 25 ° C), obtainable by concentrating a solution of such Mass to a hotmelt processable system.
The concentration can take place in suitably equipped boilers or extruders, in particular in the concomitant degassing, a degassing extruder is preferred.
Such an adhesive is set forth in DE 43 13 008 C2. These acrylate masses produced in this way are completely removed from the solvent in an intermediate step.

The K value is determined in particular in analogy to DIN 53 726.

In addition, further volatile constituents are removed. After coating from the melt, these materials have only low levels of volatile components. Thus, all claimed in the above-mentioned patent monomers / formulations can be adopted. Another advantage of the compositions described in the patent is the fact that they have a high K value and thus a high molecular weight. It is known to those skilled in the art that systems with higher molecular weights can be crosslinked more efficiently. This reduces the proportion of volatile components accordingly.

The solution of the composition may contain from 5 to 80% by weight, in particular from 30 to 70% by weight, of solvent.

Commercially available solvents are preferably used, in particular low-boiling hydrocarbons, ketones, alcohols and / or esters.

Further preferably, single-screw, twin-screw or multi-screw extruders with one or in particular two or more degassing units are used.

In the adhesive based on Acrylathotmelt-based benzoin derivatives may be copolymerized, such as benzoin acrylate or benzoin methacrylate, acrylic acid or methacrylic acid ester. Such benzoin derivatives are described in EP 0 578 151 A.

The acrylate-based adhesive can be UV-crosslinked. Other types of crosslinking are also possible, for example electron beam crosslinking.

In a particularly preferred embodiment, self-adhesive compositions of (meth) acrylic acid and esters thereof having 1 to 25 carbon atoms, maleic, fumaric and / or itaconic acid and / or their esters, substituted (meth) acrylamides, maleic anhydride and other vinyl compounds , used as vinyl esters, in particular vinyl acetate, vinyl alcohols and / or vinyl ethers.

The residual solvent content should be below 1% by weight.

Furthermore, an adhesive may be used which consists of the group of natural rubbers or synthetic rubbers or of any blend of natural rubbers and / or synthetic rubbers, wherein the natural rubber or natural rubbers in principle from all available qualities such as crepe, RSS, ADS , TSR or CV types, depending on the required level of purity and viscosity, and the synthetic rubber or synthetic rubbers from the group of random copolymerized styrene-butadiene rubbers (SBR), butadiene rubbers (BR), the synthetic polyisoprenes ( IR), butyl rubbers (IIR), halogenated butyl rubbers (XIIR), acrylate rubbers (ACM), ethylene-vinyl acetate copolymers (EVA) and polyurethanes and / or blends thereof.

Further, it is preferable to add to the rubbers, for the purpose of improving the processability, thermoplastic elastomers having a weight proportion of 10 to 50% by weight, based on the total elastomer content.
Representative may be mentioned at this point especially the most compatible styrene-isoprene-styrene (SIS) and styrene-butadiene-styrene (SBS) types.

As tackifying resins, all previously known adhesive resins described in the literature can be used without exception. Mention may be made representative of the rosins, their disproportionated, hydrogenated, polymerized, esterified derivatives and salts, the aliphatic and aromatic hydrocarbon resins, terpene resins and terpene phenolic resins. Any combination of these and other resins can be used to adjust the properties of the resulting adhesive as desired.

The presentation of the state of knowledge in the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, 1989) is expressly pointed out.

Hydrocarbon resin is a collective term for thermoplastic, colorless to intense brown colored polymers having a molecular weight of generally <2000.

They can be classified according to their provenance in three major groups: In petroleum, coal tar and terpene resins. The most important coal tar resins are the coumarone-indene resins. The hydrocarbon resins are obtained by polymerization of the unsaturated compounds which can be isolated from the raw materials.

The hydrocarbon resins are also calculated by polymerization of monomers such as styrene or by polycondensation (certain formaldehyde resins) accessible polymers having a correspondingly low molecular weight. Hydrocarbon resins are products with a softening range varying from <0 ° C (at 20 ° C liquid hydrocarbon resins) to> 200 ° C in a wide range and a density of about 0.9 to 1.2 g / cm ³ .

They are soluble in organic solvents such as ethers, esters, ketones and chlorinated hydrocarbons, insoluble in alcohols and water.

Rosin resin is understood to mean a natural resin derived from the crude resin of conifers. A distinction is made between three types of rosin: balsam resin as distillation residue of turpentine oil, root resin as extract of coniferous rootstocks and tall resin, the distillation residue of tall oil. The most important in terms of quantity is balsam resin.

Rosin is a brittle, transparent product of red to brown color. It is insoluble in water but soluble in many organic solvents such as (chlorinated) aliphatic and aromatic hydrocarbons, esters, ethers and ketones as well as in vegetable and mineral oils. The softening point of rosin is in the range of about 70 to 80 ° C.

Rosin is a mixture of about 90% resin acids and 10% neutral substances (fatty acid esters, terpene alcohols and hydrocarbons). The most important rosin resin acids are unsaturated carboxylic acids of the general formula C20H30O2, abietic, neoabietin, Levopimaric, pimaric, isopimaric, and palustric acids, in addition to hydrogenated and dehydrated abietic acid.
The proportions of these acids vary depending on the provenance of the rosin.

As plasticizers, it is possible to use all softening substances known from adhesive tape technology. These include, among others, the paraffinic and naphthenic oils, (functionalized) oligomers such as oligobutadienes, isoprenes, liquid nitrile rubbers, liquid terpene resins, vegetable and animal oils and fats, phthalates, functionalized acrylates.

For the purpose of thermally induced chemical crosslinking, all known thermally activatable chemical crosslinkers such as accelerated sulfur or sulfur donor systems, isocyanate systems, reactive melamine, formaldehyde and (optionally halogenated) phenol-formaldehyde resins or reactive phenolic resin or Diisocyanatvemetzungssysteme with the corresponding activators, epoxidized polyester - And acrylate resins and their combinations used.
The crosslinkers are preferably activated at temperatures above 50 ° C, in particular at temperatures of 100 ° C to 160 ° C, most preferably at temperatures of 110 ° C to 140 ° C.
The thermal excitation of the crosslinkers can also be done by IR radiation or other high-energy electromagnetic alternating fields.

With reference to the figures described below, particularly advantageous embodiments of the invention are explained in more detail without wishing to be unnecessarily limited by the choice of the figures shown.

Figur 1

das erfindungsgemäße Verfahren in einer besonders vorteilhaften Ausführungsform sowie

Figur 2

das erfindungsgemäße Verfahren in einer zweiten besonders vorteilhaften Ausführungsform.

Show it

FIG. 1

the inventive method in a particularly advantageous embodiment and

FIG. 2

the inventive method in a second particularly advantageous embodiment.

Thus, FIG. 1 shows a device in which an adhesive 8 is applied to a substrate 7. It thus shows a process for the production of adhesive tapes.
The device has a lay-on roller 6 with a thin electrically insulating coating 10. In this case, a grounded cooling roll is used. The substrate 7 is a release liner, consisting of a monoaxially stretched polypropylene film, which was equipped on both sides with anti-adhesive silicone layers. The coating 10 is intended to reduce damage to the anti-adhesive silicone layers caused by the electrostatic application.
The substrate 7 is placed on the laying roller 6 with an electrically insulating coating 10 via a pressure roller 4, which removes the air between the substrate 7 and the laying roller 6. Finally, via the coating nozzle 5, the mass 8, in this case an adhesive, is applied, which is carried out under the lay-up electrode 1.
With the lay-on electrode 1 here ions are applied on one side to the mass 8. Under the electrically insulating coating 10 of the laying roller 6 counter-charges are immediately set. From the resulting field, a force acts on the mass plus substrate, which presses both layers onto the lay-up roller 6.
After passing through the counter-charging electrode 2 and the discharge electrode 3, the coated with the mass 8 substrate 7 is removed from the laying roller 6.
The counter-charging electrode 2 brings opposite charges as the charging electrode to the mass 8, so that the charges largely neutralize.

At the discharge electrode 3, finally, the last charges on the ground 8 are removed.
With the aperture 9 in front of the lay-on electrode 1, the space enriched with ions is limited.
The lay-up roller 6 is provided with an insulating coating 10, in this case a PET casting resin.
With the discharge electrode 11, a charge of the insulator layer 10 is to be prevented.

FIG. 2 shows a device in which an adhesive 8 is applied to a substrate 7. It thus shows a process for the production of adhesive tapes.

The device has a lay-on roller 6, over which an electrically conductive conveyor belt 10 runs with a thin electrically insulating coating. It is used a grounded cooling roll. The substrate 7 is a release liner consisting of a release paper, which has been equipped on both sides with anti-adhesive silicone layers. The conveyor belt 10 with an electrically insulating coating is intended to reduce damage to the anti-adhesive silicone layers caused by the electrostatic application.
The substrate 7 is placed over a pressure roller 4 on the laying roller 6, with the conveyor belt 10 therebetween. Finally, via the coating nozzle 5, the mass 8, in this case an adhesive, is applied, which is carried out under the lay-up electrode 1.
With the lay-on electrode 1 here ions are applied on one side to the mass 8. Under the electrically insulating coating of the grounded via the laying roller conveyor belt 10 immediately counter charges. From the resulting field, a force acts on the mass plus substrate, which presses both layers onto the conveyor belt 10.
After passing through the counter-charging electrode 2 and the discharge electrode 3, the coated with the mass 8 substrate 7 is removed from the laying roller 6.
The counter-charging electrode 2 brings opposite charges on the mass 8, so that the charges largely neutralize.
At the discharge electrode 3, finally, the last charges on the ground 8 are removed.
With the aperture 9 in front of the lay-on electrode 1, the space enriched with ions is limited.
With the discharge electrode 11, a charge of the insulator layer of the conveyor belt 10 is to be prevented.
The discharge electrode 12 prevents damage to the silicone layers during the removal of the coated substrate from.

Examples example 1

An acrylate adhesive was polymerized in solvents and concentrated in an extruder. In another extruder, resins were used as anti-aging agents and other additives added. The coating of the mass was carried out via a melt pump through a slot die (Extrusion Dies Inc./USA), with a coating width of 35 cm on a 70 micron thick polypropylene release film, which was placed with a pressure roller on a temperature-controlled application roller. On the coated side of this film, which was coated on both sides with 0.5 g / m ² anti-adhesive silicone layers, a 50 μm thick BOPP film was laminated in a subsequent laminating station. Thereafter, the laminate was wound up.

To charge the ground layer, a needle electrode was used as a lay-on electrode (type: R130A from Eltex), which was supplied by a high-voltage generator (type KNH34 / N from Eltex). In addition, a similar second needle electrode (counter charge electrode) in the area between the ground contact line and the line of departure of the coated substrate from the lay-up roller was attached and supplied by another high voltage generator (type KNH34 / P from. Eltex) with high voltage of the opposite polarity. The laying electrode was subjected to a negative high voltage of -15.8 kV at a line speed of 75 m / min. The distance of the needle tips from the roll surface, the position of the electrode in the web running direction and the angle of inclination of the electrode to the tangent of the lay-up roll were optimized until no bubbles could be observed between mass and substrate. The needle spacing was about 5 mm from the roll surface, the position of the electrode was about 8 mm in the web running direction behind the laying point and the angle of inclination to the tangent of the laying roll was 90 °.

The counter-charge electrode was covered with an opposite, ie positive, high voltage of +13.7 kV, so that the absolute value of the electrode current was equal to that of the lay-up electrode and the coated substrate was thus electrostatically neutralized before leaving the roll. The distance of the needle tips of the counter-charging electrode from the roll surface was about 12 mm.
However, an active discharge electrode (type R51 A from Eltex), which was supplied with 8 kV alternating current at a frequency of 50 Hz from a power supply unit (Eltex type: ES52), was additionally supplied over the detachment line of the web from the lay-up roll.

The aim of the test was, at a coating speed of 85 m / min and a mass application of 85 g / m ^2, a damage found in the above experimental setup reduce the anti-adhesive properties of the release film without bubbles between mass and substrate are observed.

Blistering was determined on the one hand in-line with a camcorder, a strong light source and a monitor with the help of still images at exposure times between 100 and 1000 microseconds and on the other hand by observing patterns after stopping the web.

In the following, the lay-up roll was wrapped with one layer of polyester film of different thicknesses. At the interface, the beginning and the end of the film overlapped. The beginning was fixed with an adhesive film on the roll shell and the end corresponding to the beginning of the film. Bubbles between mass and substrate were formed at the seams at much lower web speeds than in the remaining area.
The Folienumwicklungen tended, however, to uncontrolled electrostatic charging. An active discharge electrode (type R51A from Eltex) was therefore placed in the region not covered by the substrate between the draw line of the coated substrate and the application roller and the pressure roller.
The following web speeds could be achieved bubble-free with different thick film wrappings: 190 μm PET film 40 m / min 75 μm PET film 75 m / min 50 μm PET film 85 m / min 25 μm PET film 85 m / min

In the following, the damage of the anti-adhesive properties of the release film in the experimental setting with the 50 micron PET film and 85 m / min, and at the same speed without film coverage of the lay-up roll was determined. Care was taken to ensure that the seams did not flow into the measurement results.

The damage was determined with the following measuring method.

Measurement of the separation force

On the side of the release liner to be measured, a double-sided test adhesive tape is applied bubble-free and pressed with a 2 kg steel roller by rolling over five times. This is followed by storage for one week in a heating chamber at 70.degree. To measure the pull-off force (release force), the side of the test band facing away from the release liner is fixed on a steel rail. Subsequently, the release liner adhered to the test tape is peeled off at an angle of 180 ° at a speed of 300 mm / min. The required tensile force (in cN / cm) is measured on a tensile tester under standardized conditions (23 ° C, 50% humidity).

The minimum, the maximum and the average of five individual measurements are given. Measured separation forces with the specified measuring method minimum maximum Average Undamaged reference pattern 8 cN / cm 10 cN / cm 9 cN / cm Open side of the release film lay-up roller not covered 17 cN / cm 30 cN / cm 24 cN / cm Covered side of the release film lay-up roller not covered 14 cN / cm 20 cN / cm 17 cN / cm Open side of the release film lay-up roller covered with 50 μm PET 15 cN / cm 23 cN / cm 19 cN / cm Covered side of the release film lay-up roller covered with 50 μm PET 13 cN / cm 17cN / cm 15 cN / cm

The results show that in a roll wrap with an electrical insulator the release film was less damaged. When wrapping the lay-up roll with thicker foils, however, the achievable web speed is reduced without bubbles.

Example 2

In this experiment, the same structure as in Example 1 was chosen. However, the substrate was passed over the lay-up roll on a conveyor belt. An additional An active discharge electrode was placed over the discharge line of the coated substrate from the transfer belt, and the roller winding discharge electrode was displaced so as to face against the side of the conveyance belt facing the substrate.
First, a 3 mm thick non-conductive belt cloth with fabric reinforcement was used on the coater. Only a web speed of 20 m / min without bubbles between coating and substrate was achieved. In particular, at higher speeds, the tissue structure in the webbing, despite a smooth surface to the substrate, was distinguished in the image of the bubbles between the coating and the substrate.
In the following, instead of the existing belt cloth, the same PET films were used as in Experiment 1. They were guided over the same deflection and tensioning rollers and the web edge control as the belt.
The test results with regard to the achievable bubble-free web speed and the damage to the release film are identical within the scope of the measurement accuracies.

Example 3

In this experiment, the same structure as in Example 1 was chosen. Instead of wrapping the lay-up roll with a film, the lay-up roll was coated bubble-free with a PET casting resin. The coating was in excess. In the following operation, the coating was removed to a thickness of 100 microns with an accuracy of ± 3 microns and polished.
With this relatively high thickness of this roller coating (see Example 1), a web speed of 70 m / min was achieved without bubbles. The damage to the release film could be lowered as in the Walzenumwicklungen. The following values were achieved with the measuring method indicated in Example 1: minimum maximum Average Undamaged reference pattern 7 cN / cm 11 cN / cm 9 cN / cm Open side of the release film 15 cN / cm 22 cN / cm 18 cN / cm Covered side of the release film 14 cN / cm 18 cN / cm 16 cN / cm Within the measuring accuracy, these values correspond to those with the wrapping with a 50 μm PET film in Example 1.

Claims (24)

1. Process for producing products in web form comprising at least two layers, in which a composition emerging from an applicator is applied as a layer to a substrate in web form which is guided on a transport means, said application taking place with application of electrostatic charges, so that on the surface of the transport means countercharges come about and the resulting field causes a force to act on the composition plus substrate, which presses both coats onto the transport means, so that no air bubbles are included between the composition layer and the substrate, and in which the substrate coated with the composition is electrostatically neutralized before departing the transport means, the transport means being provided with an electrically insulating coating and the composition being an adhesive.
2. Process according to Claim 1, characterized in that said applicator is configured as a die, in particular a slot die, two-manifold or multiple-manifold die or adaptor die.
3. Process according to Claim 1 or 2, characterized in that said transport means is configured as a lay-on roller, which in particular is of earthed and/or temperature-controllable design.
4. Process according to at least one of the preceding claims, characterized in that the composition is electrostatically charged by means of at least one lay-on electrode which is located in particular above the transport means, preferably lay-on roller, in the region of the lay-on line of the composition coat.
5. Process according to at least one of the preceding claims, characterized in that as a lay-on electrode two needle electrodes arranged directly following one another in the web direction are used, the needles in particular being laterally offset by half the distance of a needle.
6. Process according to at least one of the preceding claims, characterized in that the substrate coated with the composition is electrostatically neutralized by means of at least one countercharging electrode before departing the transport means, preferably lay-on roller, the counterelectrode being located in particular over the transport means, preferably lay-on roller, in the region between the lay-on line of the composition coat and the take-off line of the coated substrate.
7. Process according to at least one of the preceding claims, characterized in that the substrate coated with the composition is kept electrostatically neutral by means of at least one discharge electrode on departing the transport means, preferably lay-on roller, the discharge electrode being located in particular over the transport means, preferably lay-on roller, in the region of the take-off line of the coated substrate.
8. Process according to at least one of the preceding claims, characterized in that the electrically insulating coating of the transport means, preferably lay-on roller, is electrostatically neutralized by means of at least one discharge electrode upstream of the lay-on line of the substrate onto the transport means.
9. Process according to at least one of the preceding claims, characterized in that the substrate is placed with a contact roller onto the transport means, preferably lay-on roller, and/or is removed from the transport means, preferably lay-on roller, with a take-off roller.
10. Process according to at least one of the preceding claims, characterized in that a baffle made of electrically insulating material is mounted in the running direction of a web between the applicator and the lay-on electrode.
11. Process according to at least one of the preceding claims, characterized in that the substrate is electrostatically neutralized prior to coating.
12. Process according to at least one of the preceding claims, characterized in that the composition on the substrate is crosslinked before departing the transport means, preferably lay-on roller, in particular by means of electron beams, UV rays, visible light or thermally or by means of a combination of said processes.
13. Process according to at least one of the preceding claims, characterized in that the thickness of the coating is less than 300 µm, in particular between 30 and 200 µm, very particularly between 40 and 120 µm, and/or the thickness deviates by not more than ± 20% from the average value, in particular not more than ± 5%, over the entire surface of the transport means.
14. Process according to at least one of the preceding claims, characterized in that the coating has a low roughness and/or antiadhesive properties.
15. Process according to at least one of the preceding claims, characterized in that the coating is composed of polyester, Teflon, capton, silicone rubber, polypropylene, casting resin or other materials having sufficient high-voltage resistance at low coat thickness.
16. Process according to at least one of the preceding claims, characterized in that the coating used is a shrink sleeve which is pulled over the transport means, especially a lay-on roller, and shrunk.
17. The process as claimed in at least one of the preceding claims, characterized in that a conductive sleeve with an insulating coating is pulled over a transport means configured, in particular, as a lay-on roller.
18. Process according to at least one of the preceding claims, characterized in that the substrate is guided over a lay-on roller on an electrically conductive conveyor belt which is coated with an electrical insulator.
19. Process according to at least one of the preceding claims, characterized in that the substrate is guided over a lay-on roller on a thin conveyor belt composed of an electrical insulator, preferably with thicknesses of between 20 µm and 300 µm and in particular between 20 µm and 120 µm.
20. Process according to at least one of the preceding claims, characterized in that the substrate is guided over a conductive transport means, preferably lay-on roller, on a thin, electrically insulating auxiliary sheet, with thicknesses of preferably between 20 µm and 300 µm and in particular between 20 µm and 120 µm, which is unwound from a bale, and in that the auxiliary sheet is subsequently wound up into a bale again.
21. Process according to at least one of the preceding claims, characterized in that the substrate is a release liner for an adhesive tape.
22. Process according to at least one of the preceding claims, characterized in that the substrate is an initial product consisting of release liner, adhesive, and carrier for a double-sided adhesive tape and the composition is an adhesive.
23. Process according to at least one of the preceding claims, characterized in that the substrate is a release liner and the coating, consisting of a first adhesive, carrier, and a second adhesive, is applied from a triple-manifold or adaptor die.
24. Process according to at least one of the preceding claims, characterized in that said composition comprises acrylic, natural rubber, synthetic rubber or EVA adhesives.

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