Die-cut, especially for temporarily closing holes

Abstract

Die cut (2), in particular for temporarily closing holes (10), in particular in sheet metal or in plastic parts, consisting of a carrier (4), the carrier being coated on one side with an adhesive (5), in particular a curable or self-adhesive adhesive, wherein the die-cut (2) has an adhesive area (9) and a grip area (3), wherein the grip area (3) is located in the delivery state with the adhesive area (9) in one plane, the die-cut plane, wherein the grip area (3) is not adhesive, characterized in that the grip area (3) consists of two sections (3a, 3b), a connecting section (3a) and a supporting section (3b), wherein the connecting section (3a) is connected to the adhesive area (9) of the die-cut (2) and, in the applied state, is inclined by an angle α from the die-cut plane and wherein the support section (3b) in the applied state is only connected to the connecting section (3a) and ensures the inclination of the connecting section (3a) from the die-cut plane.

Description

[0001] The present invention relates to a die-cut, in particular for temporarily closing holes, in particular in metal sheets or in plastic parts, consisting of a carrier, wherein the carrier is coated on one side with an adhesive, in particular a curable or self-adhesive adhesive, and to a method for temporarily closing holes.

[0002] When manufacturing more complex structures from sheet metal and / or plastic, it is necessary to cut holes into the sheet metal or plastic to access the cavities behind them, whether for painting or welding. Additional holes in the form of threaded holes are required to connect sheet metal and / or plastic parts.

[0003] During the manufacturing process, it may be necessary to temporarily seal such holes, for example, if the parts containing the holes are to be painted or otherwise coated. In this case, it may be necessary to protect the holes from being contaminated by the paint or even sealed.

[0004] Especially in the production of modern vehicles such as watercraft, land vehicles (trucks, automobiles, etc.), aircraft, spacecraft, and combinations thereof, for example, amphibious vehicles, it is inevitable that holes of varying sizes are required in many individual parts made of sheet metal or plastic during assembly. The diameters of the holes are typically between 5 and 50 mm. Many of these holes must be sealed at least once during the process to prevent clogging.

[0005] The problems underlying the invention and their solution are described below using the example of an automobile body. This application is part of the technical field in which the invention is particularly advantageous. From now on, when use in a body is mentioned, the person skilled in the art will also consider all other possible applications outside of a body.

[0006] In automotive construction, holes must be created or punched out at various points in the body. This usually occurs during the stamping and forming process of the individual sheet metal or aluminum parts, but holes can also be drilled in plastic components. The individual metal parts are then joined together using various joining processes, creating the bodyshell. The holes, openings, or penetrations contained therein serve, among other things, as paint drainage holes (for example, for cathodic dip painting), wax injection holes, wax drainage holes, holes for later screw connections during assembly, or for cable feedthroughs. Many of these holes must be sealed after the cathodic dip coating (CDP) has dried to protect them from contamination before the subsequent painting process – usually three steps: filler, basecoat, and clearcoat.

[0007] Typically, the holes or openings are sealed using injection-molded parts (plugs) made from various plastics, manufactured to meet specific requirements. These can include plugs made from PET, ABS, PP, PVC, EPDM, PA, and other commonly available plastics, or combinations of the aforementioned materials and commercially available plastic substrates not listed here. Materials containing glass fibers are also used; carbon fibers are also conceivable, providing reinforcement for the plug, for example, to prevent puncture. In principle, all common plastic substrates are possible, as long as they meet certain parameters regarding paintability, temperature stability, dimensional stability under climatic conditions, and also meet a certain level of cost-effectiveness in the plug manufacturing process.

[0008] Currently, plastic plugs are generally used to close bodywork holes. These plugs, on the one hand, do not securely seal the hole in individual cases, but can easily fall out of the thread, and on the other hand, are comparatively complex and expensive to manufacture. Each hole size requires a special plug adapted to the hole size. This represents a significant logistical and administrative burden for the plug purchaser. For example, a large number of plugs of various sizes must be kept on the production line in dedicated storage bins.

[0009] Adhesive tapes that can be cut to size or punched to fit the hole size are also suitable for this purpose. However, even adhesive tapes don't always meet the increasing demands of the market.

[0010] For example, the die-cuts described in WO 2006 / 053 827 A1 are suitable for sealing holes. They consist of a base layer made of a heat-resistant carrier that is at least partially self-adhesive on one side. The base layer's surface area is larger than the surface area of ​​the hole to be sealed and, in particular, is provided centrally on the adhesive side with a first section of a heat-activatable adhesive film. The first section's surface area is larger than the surface area of ​​the hole to be sealed and smaller than the surface area of ​​the base layer. The die-cut is applied over the hole to be sealed in such a way that the hole is essentially covered by the first section. The heat-activatable adhesive films described are well suited for sealing, but are comparatively expensive. Furthermore, they are very difficult to remove once they are no longer needed.

[0011] The same applies to the die-cuts described in WO 2005 / 097 582 A1. These offer the possibility of incorporating a component into the die-cut that, at elevated temperatures such as during a drying step in the painting area, completely fills and / or covers the hole by foaming, which should ensure reliable closure of the hole. However, it has been shown that the unfoamed component must exhibit considerable expansion to ensure complete hole closure, since the direction of expansion is limited only by the adhesive side to the one-sided self-adhesive die-cut. Such a hole closure exhibits only low strength with regard to foam adhesion to the sheet metal, since the material only comes into contact with the edge of the hole and little contact with the sheet metal on the side facing away from the die-cut. Nevertheless, removing the die-cut is difficult.

[0012] Until now, such die-cuts have typically been removed using a spatula. Unfortunately, this has been shown to easily damage the e-coating, leading to subsequent corrosion.

[0013] The object of the invention is to provide a punched part which is suitable for temporarily closing holes, in particular in sheet metal or in plastic parts of automobile bodies, which reliably closes said holes, but when it is no longer required and the hole has to be released again, can be removed easily and without damaging the surface to which it was temporarily attached.

[0014] This object is achieved by a die-cut of the type mentioned at the outset, which has an adhesive area and a grip area, wherein the grip area is located in the delivery state with the adhesive area in one plane, the die-cut plane, wherein the grip area is not adhesive and wherein the grip area consists of two sections, a connecting section and a supporting section, wherein the connecting section is connected to the adhesive area of ​​the die-cut and, in the applied state, is inclined by an angle α from the die-cut plane and wherein the supporting section, in the applied state, is only connected to the connecting section and ensures the inclination of the connecting section from the die-cut plane.

[0015] This design of the die-cut allows the grip area, with its connecting section and support section, to form a specially shaped, raised tab. This tab can be gripped without the use of tools even after painting, and allows the die-cut to be easily removed from the surface, particularly without the need for scraping or scratching with a spatula. This protects the paint and the e-coating as much as possible when removing the die-cut part.

[0016] The formation of the raised tab is carried out in particular as follows: separating the support section of the grip area from the adhesive section; folding out the grip area from the die-cut plane; Fold the support section between the support section and the connecting section towards the connecting section until the support section forms a substantially right angle with the line between the connecting section of the grip area and the adhesive area.

[0017] For the purposes of the present invention, the "as delivered" condition refers to the condition the die-cut has after its completion in production until its intended application to the hole. The "applied" condition is the condition after the die-cut has been glued and the grip area has been raised.

[0018] The area around the hole to be sealed is usually flat, at least in the area where the die-cut is applied. This plane, in which the adhesive area of ​​the die-cut is located in its applied form, is referred to as the die-cut plane.

[0019] Typically, a die-cut will have one grip area, although it is not impossible for two or more grip areas to be provided, especially if large holes are to be covered.

[0020] There are two options for making the grip area non-adhesive. First, no adhesive can be applied to the grip area, so the grip area consists only of the carrier. This design is particularly cost-effective and resource-efficient because, on the one hand, no cover layer is required and, on the other hand, less adhesive is used.

[0021] The other option is to coat the entire surface of the carrier with adhesive, and then apply a cover layer to the adhesive in the grip area. This variant is particularly easy to manufacture because the entire carrier surface is coated with adhesive, and then the cover layer is applied to the desired areas to form the grip area. This also allows for a particularly stable grip area. The degree of stability can be varied depending on the material used for the cover layer.

[0022] Regardless of the design of the grip area, the carrier can consist of a single layer or be a laminate of two or more layers. Suitable carrier materials are described in detail below.

[0023] Particularly good handling is achieved by providing an embossed pattern in the form of a first line between the connecting section of the pull tab and the adhesive area. This embossing makes it particularly easy to fold the pull tab out of the die-cut. The embossing allows for precise and reproducible folding. Furthermore, it particularly prevents accidental folding of part of the adhesive area, which could result in insufficient adhesive surface being available to cover the hole.

[0024] Furthermore, it is preferred if an embossing in the form of a second line is provided between the two sections of the grip area, i.e., between the connecting section and the support section. Here, too, the embossing enables particularly simple and secure folding of the sections toward each other at the desired location.

[0025] When applying the die-cut, it is important to ensure that the support section of the grip area is separated from the adhesive area after it has been applied to the hole to be closed. This can either be done during production of the die-cut, in which the support section and adhesive area are separated from each other by a cut. In a particularly advantageous embodiment, the support section of the grip area is connected to the adhesive section by a perforation in the form of a line in the delivered state. In this way, the die-cut is initially compact, but the two sections can be easily separated at a defined location.

[0026] The angle α by which the connecting section is inclined from the plane of the die-cut is preferably in a range of 45° to 120°, with an angle in the range of 90° ± 10° being particularly preferred, and the simplest geometry being obtained for an angle of 90°, so a right angle is particularly preferred. If the angle α = 90°, the lines separating the connecting section and the adhesive area, as well as the support section and the adhesive area, lie on a straight line, which makes both the production of the die-cut and its handling during application particularly simple.

[0027] The die-cut is preferably formed as a circle, although other geometries, such as ovals, rectangles, or squares, are also conceivable; a circular shape is preferred.

[0028] Both the carrier and the cover layer can be formed as a film made of any polymer, either alone or in a mixture. Suitable polymers are olefinic polymers such as homopolymers or copolymers of olefins such as ethylene, propylene, or butylene (the term "copolymer" is to be understood here as including terpolymers), polypropylene homopolymers, or polypropylene copolymers, including block (impact) and random polymers.

[0029] Further polymers can be selected from the group of polyesters such as, in particular, polyethylene terephthalate (PET), polyamides, polyurethanes, polyoxymethylene, polyvinyl chloride (PVC), polyethylene naphthalate (PEN), ethylene vinyl alcohol (EVOH), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polycarbonate (PC), polyamide (PA), polyethersulfone (PES), polyimide (PI), polyarylene sulfides and / or polyarylene oxides.

[0030] The film is preferably made of polyester (in particular polyethylene terephthalate (PET)), polyurethane or PVC.

[0031] According to a further embodiment, the carrier and / or the cover layer can also comprise more than one film. In particular, the carrier film can consist of an at least two-layer laminate made of two or more film layers of any material (e.g., polyethylene, polypropylene, polyester, PA, and / or PVC). It is possible for one of the film layers to be a heavy film, such as a mineral-filled polyolefin film or an elastomer-modified bitumen film.

[0032] A heavy-duty foil consists of a foil-like layer of any thickness, in particular from 0.015 mm to over 12 mm. The heavy-duty foil is composed primarily of thermoplastic polymers, especially PE (polyethylene), EPDM (ethylene-propylene-diene rubber), and / or EVA (ethylene-vinyl acetate), and mineral fillers, especially limestone powder or calcite (CaCO3) and barite (BaSO4). Talc, slate powder, graphite, mica, or asbestos (the latter less commonly used today) can also be used for filling.

[0033] In an advantageous embodiment of the invention, a layered body consisting of metal, a metal foil, for example aluminum foil, or a metal-containing foil is present in a multilayer carrier (between two foil layers) or on the carrier.

[0034] For example, a punchable aluminum sheet, a corrosion-resistant steel sheet, or an aluminum foil with a scrim for reinforcement or strength can be laminated to the foil.

[0035] The polymers used to form the films used in the laminate can be present in pure form or in blends with additives such as antioxidants, light stabilizers, antiblocking agents, lubricants and processing aids, fillers, dyes, pigments, blowing agents, or nucleating agents. Preferably, the films do not contain any of the aforementioned additives.

[0036] According to a preferred embodiment, the thickness of the films used, unless it is a heavy film, is between 15 and 350 µm, preferably between 30 and 200 µm, more preferably between 50 and 150 µm.

[0037] According to a preferred embodiment, the thickness of a heavy foil layer is between 600 and 3500 µm, preferably between 1100 and 3500 µm, more preferably between 1700 and 3500 µm. According to a further preferred embodiment, the thickness of a heavy foil layer is between 600 and 1100 µm, between 1100 and 1700 µm, or between 1700 and 3500 µm.

[0038] In a further advantageous embodiment of the invention, in the case of the carrier and / or cover layer, the film or at least one of the films of a laminate is reinforced by integrated or attached fibers or filaments, so that their strength is increased, in particular in the longitudinal direction.

[0039] For the purposes of this invention, a filament is understood to be a bundle of parallel, straight individual fibers, often referred to in the literature as a multifilament. If necessary, this fiber bundle can be consolidated by twisting; in this case, it is referred to as spun or twisted filaments. Alternatively, the fiber bundle can be consolidated by intermingling with compressed air or a water jet. From now on, the term "filament" will be used for all of these embodiments—as well as for the fiber-reinforced embodiment.

[0040] If a film is reinforced exclusively by filaments integrated / attached in the longitudinal direction, it is referred to as a monofilament adhesive tape. In an advantageous development of the subject matter of the invention, the upper film and / or the lower film are reinforced by an open filament weave. In this case, it is referred to as a cross-filament adhesive tape.

[0041] High-strength fibers, twines, blended twines or threads with low elongation at break are added as filaments.

[0042] The individual filaments are preferably continuous filaments and / or have a fineness between 4 and 8 dtex, preferably 5 dtex. In an advantageous embodiment, all filaments are continuous filaments. In a preferred embodiment, there are between 1 and 30 filaments per centimeter of width in the carrier material, in particular between 1 and 5.

[0043] The filaments can be made of organic or inorganic materials, for example and preferably of glass, carbon, combinations of both fiber types, aramid fibers or special polyamides, or of stretched polymer fibers such as polyester fibers, polypropylene fibers, or polyethylene fibers. Furthermore, the reinforcing fibers can be at least partially colored to make the carrier material more visually appealing. This makes it easy to visually differentiate the reinforced carriers. Colored glass or polymer threads are particularly suitable for this purpose.

[0044] The film(s) are preferably laminated with the filaments. The filaments should be firmly bonded to the film(s). This can be achieved by directly incorporating or embedding the fibers, threads, yarns, or blended yarns into the film(s), for example, by weaving in woven fabrics, knitting in knitted fabrics, or embedding or inserting them during the manufacturing process.

[0045] The filaments can also be subsequently bonded to the film(s), for example by welding or laminating with an appropriate bonding layer.

[0046] Furthermore, the reinforcements are preferably inserted according to the direction of stress on the support or covering layer, i.e., primarily in the longitudinal direction. However, if more appropriate, they can also be arranged transversely or diagonally, or in a curved, spiral, zigzag pattern, or randomly.

[0047] Paper can also be used as a material for the cover layer, particularly anti-adhesive release paper, for example, based on various high-density papers such as glassine papers. The paper carrier is provided on the top and / or bottom side with a plastic coating, for example in the form of a film, with an anti-adhesive layer applied to at least one of the two plastic coatings, if present.

[0048] In a preferred variant, the adhesive applied to the carrier is a pressure-sensitive adhesive, i.e., an adhesive that allows a permanent bond to almost all substrates even under relatively light pressure and can be removed from the substrate after use, leaving essentially no residue. A pressure-sensitive adhesive is permanently tacky at room temperature, i.e., it has a sufficiently low viscosity and high tackiness, allowing it to wet the surface of the respective substrate even under light pressure. The adhesive's bondability is based on its adhesive properties, and its removability on its cohesive properties.

[0049] All known adhesive systems can be used. In addition to natural or synthetic rubber-based adhesives, silicone adhesives and polyacrylate adhesives, preferably a low-molecular-weight acrylic hotmelt pressure-sensitive adhesive, are particularly suitable.

[0050] Adhesives based on acrylate or silicone are preferred.

[0051] The adhesive can be selected from the group of natural rubbers or synthetic rubbers or from any blend of natural rubbers and / or synthetic rubbers, whereby the natural rubber or natural rubbers can basically be selected from all available qualities such as crepe, RSS, ADS, TSR or CV types, depending on the required purity and viscosity level, and the synthetic rubber or synthetic rubbers can be selected from the group of randomly copolymerized styrene-butadiene rubbers (SBR), butadiene rubbers (BR), synthetic polyisoprenes (IR), butyl rubbers (IIR), halogenated butyl rubbers (XIIR), acrylate rubbers (ACM), ethylene-vinyl acetate copolymers (EVA) and polyurethanes and / or their blends.

[0052] Furthermore, thermoplastic elastomers can preferably be added to the rubbers to improve processability, in a weight proportion of 10 to 50%, based on the total elastomer content. Representative examples include the particularly compatible styrene-isoprene-styrene (SIS) and styrene-butadiene-styrene (SBS) grades. Other suitable elastomers for blending include EPDM or EPM rubber, polyisobutylene, butyl rubber, ethylene-vinyl acetate, hydrogenated block copolymers of dienes (for example, by hydrogenation of SBR, cSBR, BAN, NBR, SBS, SIS, or IR; such polymers are known, for example, as SEPS and SEBS), or acrylate copolymers such as ACM. A 100% system based on styrene-isoprene-styrene (SIS) has also proven suitable.

[0053] Crosslinking is beneficial for improving the re-removability of the adhesive tape after application and can be achieved thermally or by irradiation with UV light or electron beams.

[0054] For the purpose of thermally induced chemical crosslinking, all previously 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 phenol resin or diisocyanate crosslinking systems with the corresponding activators, epoxidized polyester and acrylate resins and combinations thereof can be used.

[0055] The crosslinkers are preferably activated at temperatures above 50 °C, especially at temperatures from 100 °C to 160 °C, and most preferably at temperatures from 110 °C to 140 °C. Thermal excitation of the crosslinkers can also be achieved by IR radiation or high-energy alternating fields.

[0056] Solvent-based, water-based, or hot-melt adhesives can be used. An acrylic hot-melt adhesive is also suitable; this can have a K value of at least 20, in particular greater than 30, and can be obtained by concentrating a solution of such a adhesive to form a system that can be processed as a hot-melt. Concentration can take place in appropriately equipped tanks or extruders; a vented extruder is preferred, particularly for the associated degassing. Such an adhesive is described in DE 43 13 008 C1, the contents of which are hereby incorporated by reference. However, the acrylic hot-melt adhesive can also be chemically crosslinked.

[0057] In a further embodiment, copolymers of (meth)acrylic acid and its esters having 1 to 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, in particular vinyl acetate, vinyl alcohols and / or vinyl ethers, are used as self-adhesive compositions.

[0058] The residual solvent content should be less than 1 wt.%.

[0059] Another adhesive that has proven suitable is a low-molecular-weight acrylic hotmelt pressure-sensitive adhesive, such as those sold by BASF under the name acResin UV or Acronal®, particularly Acronal® DS 3458 or AC Resin A 260UV. This low-K adhesive achieves its application-specific properties through a final radiation-induced crosslinking process.

[0060] Finally, it should be mentioned that polyurethane-based adhesives are also suitable.

[0061] To optimize the properties, the self-adhesive mass used can be mixed with one or more additives such as tackifiers (resins), plasticizers, fillers, pigments, UV absorbers, light stabilizers, anti-aging agents, crosslinking agents, crosslinking promoters or elastomers.

[0062] Without exception, all previously known adhesive resins described in the literature can be used as tackifying resins to be added. Particularly suitable resins are, inter alia, non-hydrogenated, partially or fully hydrogenated resins based on indene, rosin and rosin derivatives, hydrogenated polymers of dicyclopentadiene, non-hydrogenated, partially, selectively or fully hydrogenated hydrocarbon resins based on C5, C5 / C9 or C9 monomer streams, terpene phenolic resins, terpene resins based on α-pinene and / or β-pinene and / or δ-limonene or hydrogenated polymers of preferably pure C8 and C9 aromatics, aromatic resins such as coumarone-indene resins or resins made from styrene or α-methylstyrene such as rosin and its derivatives such as disproportionated, dimerized or esterified resins, wherein glycols, glycerol or pentaerythritol.

[0063] Any combination of these and other resins can be used to tailor the properties of the resulting adhesive. In general, any (soluble) resin compatible with the respective polymer can be used. Reference is made to the current state of knowledge in the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, 1989).

[0064] Suitable fillers and pigments include carbon black, titanium dioxide, calcium carbonate, zinc carbonate, zinc oxide, silicates or silicic acid.

[0065] Suitable plasticizers include, for example, aliphatic, cycloaliphatic and aromatic mineral oils, di- or poly-esters of phthalic acid, trimellitic acid or adipic acid, liquid rubbers (for example nitrile or polyisoprene rubbers), liquid polymers of butene and / or isobutene, acrylic acid esters, polyvinyl ethers, liquid and soft resins based on the raw materials for adhesive resins, wool wax and other waxes or liquid silicones.

[0066] Examples of crosslinking agents include phenolic resins or halogenated phenolic resins, melamine and formaldehyde resins. Suitable crosslinking promoters include maleimides, allyl esters such as triallyl cyanurate, and polyfunctional esters of acrylic and methacrylic acid.

[0067] A "poly(meth)acrylate" is understood to mean a polymer whose monomer base consists of at least 60 wt.% acrylic acid, methacrylic acid, acrylic esters, and / or methacrylic esters, with acrylic esters and / or methacrylic esters being present at least in part, preferably at least 50 wt.%, based on the total monomer base of the polymer in question. In particular, a "poly(meth)acrylate" is understood to mean a polymer obtainable by radical polymerization of acrylic and / or methacrylic monomers and, optionally, other copolymerizable monomers.

[0068] According to the invention, the poly(meth)acrylate or poly(meth)acrylates are present in an amount of 30 to 65 wt. %, based on the total weight of the pressure-sensitive adhesive. The pressure-sensitive adhesive of the invention preferably contains 35 to 55 wt. %, based on the total weight of the pressure-sensitive adhesive, of at least one poly(meth)acrylate.

[0069] The glass transition temperature of the poly(meth)acrylates usable according to the invention is preferably < 0 °C, more preferably between -20 and -50 °C.

[0070] The glass transition temperature of polymers or polymer blocks in block copolymers is determined in this invention by means of dynamic scanning calorimetry (DSC).

[0071] The poly(meth)acrylates of the pressure-sensitive adhesive composition of the invention are preferably obtainable by at least partial copolymerization of functional monomers, preferably those crosslinkable with epoxy groups. These monomers are particularly preferably monomers containing acid groups (especially carboxylic acid, sulfonic acid, or phosphonic acid groups) and / or hydroxyl groups and / or acid anhydride groups and / or epoxy groups and / or amine groups; monomers containing carboxylic acid groups are particularly preferred. It is especially advantageous if the polyacrylate contains polymerized acrylic acid and / or methacrylic acid. All of these groups are crosslinkable with epoxy groups, thereby advantageously making the polyacrylate amenable to thermal crosslinking with incorporated epoxides.

[0072] Other monomers that can be used as comonomers for the poly(meth)acrylates, in addition to acrylic acid and / or methacrylic acid esters with up to 30 C atoms per molecule, include, for example, vinyl esters of carboxylic acids containing up to 20 C atoms, vinyl aromatics with up to 20 C atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of alcohols containing 1 to 10 C atoms, aliphatic hydrocarbons with 2 to 8 C atoms and one or two double bonds or mixtures of these monomers.

[0073] The properties of the poly(meth)acrylate in question can be influenced, in particular, by varying the glass transition temperature of the polymer through different weight proportions of the individual monomers. The poly(meth)acrylate(s) of the invention can preferably be traced back to the following monomer composition: a) Acrylic acid esters and / or methacrylic acid esters of the following formula CH2 = C(R I )(COOR II ) where R I = H or CH3 and R II is an alkyl radical with 4 to 14 C atoms, b) olefinically unsaturated monomers with functional groups of the type already defined for reactivity with epoxide groups, c) optionally further acrylates and / or methacrylates and / or olefinically unsaturated monomers which are copolymerizable with component (a).

[0074] The proportions of the corresponding components (a), (b), and (c) are preferably selected such that the polymerization product has a glass transition temperature of < 0 °C, more preferably between -20 and -50 °C (DSC). It is particularly advantageous to select the monomers of component (a) in a proportion of 45 to 99 wt. %, the monomers of component (b) in a proportion of 1 to 15 wt. %, and the monomers of component (c) in a proportion of 0 to 40 wt. % (the figures are based on the monomer mixture for the "base polymer," i.e., without any additives to the finished polymer, such as resins, etc.).

[0075] The monomers of component (a) are, in particular, plasticizing and / or nonpolar monomers. Preferably, acrylic and methacrylic acid esters with alkyl groups consisting of 4 to 14 carbon atoms, particularly preferably 4 to 9 carbon atoms, are used as monomers (a). Examples of such monomers are n-butyl acrylate, n-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, n-amyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, n-heptyl acrylate, n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, and their branched isomers, such as isobutyl acrylate, isooctyl acrylate, isooctyl methacrylate, 2-ethylhexyl acrylate, or 2-ethylhexyl methacrylate.

[0076] The monomers of component (b) are in particular olefinically unsaturated monomers with functional groups, in particular with functional groups that can react with epoxy groups.

[0077] For component (b) it is preferred to use monomers with functional groups selected from the group comprising: hydroxyl, carboxy, sulfonic acid or phosphonic acid groups, acid anhydrides, epoxides, amines.

[0078] Particularly preferred examples of monomers of component (b) are acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, aconitic acid, dimethylacrylic acid, β-acryloyloxypropionic acid, trichloroacrylic acid, vinylacetic acid, vinylphosphonic acid, maleic anhydride, hydroxyethyl acrylate, in particular 2-hydroxyethyl acrylate, hydroxypropyl acrylate, in particular 3-hydroxypropyl acrylate, hydroxybutyl acrylate, in particular 4-hydroxybutyl acrylate, hydroxyhexyl acrylate, in particular 6-hydroxyhexyl acrylate, hydroxyethyl methacrylate, in particular 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, in particular 3-hydroxypropyl methacrylate, hydroxybutyl methacrylate, in particular 4-hydroxybutyl methacrylate, hydroxyhexyl methacrylate, in particular 6-hydroxyhexyl methacrylate, allyl alcohol, glycidyl acrylate, glycidyl methacrylate.

[0079] In principle, any vinyl-functionalized compounds that are copolymerizable with component (a) and / or component (b) can be used as component (c). The monomers of component (c) can be used to adjust the properties of the resulting pressure-sensitive adhesive. Examples of monomers of component (c) are:

[0080] Methylacrylat, Ethylacrylat, Propylacrylat, Methylmethacrylat, Ethylmethacrylat, Benzylacrylat, Benzylmethacrylat, sec-Butylacrylat, tert-Butylacrylat, Phenylacrylat, Phenylmethacrylat, Isobornylacrylat, Isobornylmethacrylat, tert-Butylphenylacrylat, tert-Butylphenylmethacrylat, Dodecylmethacrylat, Isodecylacrylat, Laurylacrylat, n-Undecylacrylat, Stearylacrylat, Tridecylacrylat, Behenylacrylat, Cyclohexylmethacrylat, Cyclopentylmethacrylat, Phenoxyethylacrlylat, Phenoxyethylmethacrylat, 2-Butoxyethylmethacrylat, 2-Butoxyethylacrylat, 3,3,5-Trimethylcyclohexylacrylat, 3,5-Dimethyladamantylacrylat, 4-Cumylphenylmethacrylat, Cyanoethylacrylat, Cyanoethylmethacrylat, 4-Biphenylacrylat, 4-Biphenylmethacrylat, 2-Naphthylacrylat, 2-Naphthylmethacrylat, Tetrahydrofufurylacrylat, Diethylaminoethylacrylat, Diethylaminoethylmethacrylat, Dimethylaminoethyl-acrylat, Dimethylaminoethylmethacrylat, 2-Butoxyethylacrylat, 2-Butoxyethylmethacrylat, 3-Methoxyacrylsäuremethylester, 3-Methoxybutylacrylat,Phenoxyethylacrlylat, Phenoxyethylmethacrylat, 2-Phenoxyethylmethacrylat, Butyldiglykolmethacrylat, Ethylenglycolacrylat, Ethylenglycolmonomethylacrylat, Methoxy Polyethylenglykolmethacrylat 350, Methoxy Polyethylenglykolmethacrylat 500, Propylenglycolmonomethacrylat, Butoxydiethylenglykolmethacrylat, Ethoxytriethylenglykolmethacrylat, Octafluoropentylacrylat, Octafluoropentylmethacrylat, 2,2,2-Trifluoroethylmethacrylat, 1,1,1,3,3,3-Hexafluoroisopropylacrylat, 1,1,1,3,3,3-Hexafluoroisopropylmethacrylat, 2,2,3,3,3-Pentafluoropropylmethacrylat, 2,2,3,4,4,4-Hexafluorobutylmethacrylat, 2,2,3,3,4,4,4-Heptafluorobutylacrylat, 2,2,3,3,4,4,4-Heptafluorobutylmethacrylat, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluorooctylmethacrylat, Dimethylaminopropylacrylamid, Dimethylaminopropylmethacrylamid, N-(1-Methyl-undecyl)acrylamid, N-(n-Butoxymethyl)acrylamid, N-(Butoxymethyl)methacrylamid, N-(Ethoxymethyl)acrylamid, N-(n-Octadecyl)acrylamid, weiterhin N,N-Dialkyl-substituierte Amide,such as N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-benzylacrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, N-tert-octylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, acrylonitrile, methacrylonitrile, vinyl ethers, such as vinyl methyl ether, ethyl vinyl ether, vinyl isobutyl ether, vinyl esters, such as Vinyl acetate, vinyl chloride, vinyl halides, vinylidene chloride, vinylidene halides, vinylpyridine, 4-vinylpyridine, N-vinylphthalimide, N-vinyllactam, N-vinylpyrrolidone, styrene, α- and p-methylstyrene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, 3,4-Dimethoxystyrene, macromonomers such as 2-Polystyrene ethyl methacrylate (weight-average molecular weight Mw, determined by GPC, from 4000 to 13000 g / mol), poly(methyl methacrylate) ethyl methacrylate (Mw from 2000 to 8000 g / mol).

[0081] Monomers of component (c) can also advantageously be selected to contain functional groups that support subsequent radiation-chemical crosslinking (e.g., by electron beams, UV). Suitable copolymerizable photoinitiators include benzoin acrylate and acrylate-functionalized benzophenone derivatives. Monomers that support crosslinking by electron irradiation include tetrahydrofurfuryl acrylate, N-tert-butylacrylamide, and allyl acrylate.

[0082] The polyacrylates ("polyacrylates" is understood in the context of the invention as synonymous with "poly(meth)acrylates") can be prepared by processes familiar to the person skilled in the art, particularly advantageously by conventional radical polymerizations or controlled radical polymerizations. The polyacrylates can be prepared by copolymerization of the monomeric components using the usual polymerization initiators and, if appropriate, regulators, polymerization being carried out at conventional temperatures in bulk, in emulsion, for example, in water or liquid hydrocarbons, or in solution.

[0083] The polyacrylates are preferably prepared by polymerizing the monomers in solvents, in particular in solvents having a boiling range of 50 to 150 °C, preferably 60 to 120 °C, using the usual amounts of polymerization initiators, which are generally from 0.01 to 5, in particular from 0.1 to 2% by weight, based on the total weight of the monomers.

[0084] In principle, all conventional initiators familiar to the skilled person are suitable. Examples of radical sources are peroxides, hydroperoxides, and azo compounds, for example, dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-t-butyl peroxide, cyclohexylsulfonylacetyl peroxide, diisopropyl percarbonate, t-butyl peroctoate, and benzpinacol. A highly preferred approach uses 2,2'-azobis(2-methylbutyronitrile) (Vazo® 67™ from DuPont) or 2,2'-azobis(2-methylpropionitrile) (2,2'-azobisisobutyronitrile; AIBN; Vazo® 64™ from DuPont) as the radical initiator.

[0085] Suitable solvents for the preparation of the poly(meth)acrylates are alcohols such as methanol, ethanol, n- and iso-propanol, n- and iso-butanol, preferably isopropanol and / or isobutanol, and hydrocarbons such as toluene and in particular gasolines with a boiling range of 60 to 120 °C. Furthermore, ketones such as preferably acetone, methyl ethyl ketone, methyl isobutyl ketone and esters such as ethyl acetate and mixtures of solvents of the type mentioned can be used, with preference being given to mixtures containing isopropanol, in particular in amounts of 2 to 15% by weight, preferably 3 to 10% by weight, based on the solvent mixture used.

[0086] Preferably, concentration takes place after the production (polymerization) of the polyacrylates, and further processing of the polyacrylates is carried out essentially solvent-free. The concentration of the polymer can be carried out in the absence of crosslinking and accelerator substances. However, it is also possible to add one of these compound classes to the polymer prior to concentration, so that the concentration then takes place in the presence of this substance(s).

[0087] The weight-average molecular weights M w of the polyacrylates are preferably in a range from 20,000 to 2,000,000 g / mol; very preferably in a range from 100,000 to 1,500,000 g / mol, extremely preferably in a range from 150,000 to 1,000,000 g / mol. The data for the average molecular weight M wand polydispersity (PD) in this document refer to the determination by gel permeation chromatography. For this purpose, it may be advantageous to conduct the polymerization in the presence of suitable polymerization regulators such as thiols, halogen compounds, and / or alcohols to adjust the desired average molecular weight.

[0088] The polyacrylates preferably have a K value of 30 to 90, particularly preferably 40 to 70, measured in toluene (1% solution, 21°C). The Fikentscher K value is a measure of the molecular weight and viscosity of the polymer.

[0089] Polyacrylates with a narrow molecular weight distribution (polydispersity PD < 4) are particularly suitable for the invention. Despite their relatively low molecular weight, these materials exhibit particularly good shear strength after crosslinking. Furthermore, the lower polydispersity enables easier melt processing, as the flow viscosity is lower than that of a more broadly distributed polyacrylate while maintaining largely the same application properties. Narrowly distributed poly(meth)acrylates can be advantageously produced by anionic polymerization or by controlled radical polymerization methods, the latter being particularly suitable. Corresponding polyacrylates can also be produced via N-oxyls.Furthermore, atom transfer radical polymerization (ATRP) can be used advantageously for the synthesis of narrowly distributed polyacrylates, whereby monofunctional or difunctional secondary or tertiary halides are preferably used as initiator and Cu, Ni, Fe, Pd, Pt, Ru, Os, Rh, Co, Ir, Ag or Au complexes are used for abstraction of the halide(s).

[0090] The monomers used to produce the poly(meth)acrylates preferably contain a proportion of functional groups capable of entering into linking reactions with epoxy groups. This advantageously enables thermal crosslinking of the polyacrylates by reaction with epoxides. Linking reactions are understood to mean, in particular, addition and substitution reactions. Preferably, therefore, the building blocks bearing the functional groups are linked to building blocks bearing epoxy groups, in particular by crosslinking the polymer building blocks bearing the functional groups via crosslinker molecules bearing epoxy groups as linking bridges. The substances containing epoxy groups are preferably multifunctional epoxides, i.e., those with at least two epoxy groups; accordingly, the building blocks bearing the functional groups are preferably linked indirectly overall.

[0091] The poly(meth)acrylates of the pressure-sensitive adhesive of the invention are preferably crosslinked by linking reactions—particularly in the sense of addition or substitution reactions—of the functional groups contained therein with thermal crosslinkers. All thermal crosslinkers can be used that ensure a sufficiently long processing time so that gelling does not occur during the processing process, in particular the extrusion process, and also lead to rapid post-crosslinking of the polymer to the desired degree of crosslinking at temperatures lower than the processing temperature, in particular at room temperature. For example, a combination of polymers containing carboxyl, amine, and / or hydroxyl groups and isocyanates, in particular aliphatic or amine-deactivated trimerized isocyanates, as crosslinkers is possible.

[0092] Suitable isocyanates include, in particular, trimerized derivatives of MDI [4,4-methylenedi(phenyl isocyanate)], HDI [hexamethylene diisocyanate, 1,6-hexylene diisocyanate], and / or IPDI [isophorone diisocyanate, 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane], for example the grades Desmodur® N3600 and XP2410 (each from Bayer AG: aliphatic polyisocyanates, low-viscosity HDI trimers). Also suitable is the surface-deactivated dispersion of micronized trimerized IPDI BUEJ 339®, now HF9® (Bayer AG).

[0093] In principle, other isocyanates such as Desmodur VL 50 (polyisocyanate based on MDI, Bayer AG), Basonat F200WD (aliphatic polyisocyanate, BASF AG), Basonat HW100 (water-emulsifiable polyfunctional isocyanate based on HDI, BASF AG), Basonat HA 300 (allophanate-modified polyisocyanate based on isocyanurate, HDI, BASF) or Bayhydur VPLS2150 / 1 (hydrophilically modified IPDI, Bayer AG) are also suitable for crosslinking.

[0094] Thermal crosslinkers are preferably used at 0.1 to 5 wt.%, in particular at 0.2 to 1 wt.%, based on the total amount of the polymer to be crosslinked.

[0095] The poly(meth)acrylates of the pressure-sensitive adhesive composition of the invention are preferably crosslinked by means of epoxide(s) or by means of one or more substance(s) containing epoxy groups. The substances containing epoxy groups are, in particular, multifunctional epoxides, i.e., those with at least two epoxy groups; accordingly, the overall result is an indirect linkage of the building blocks of the poly(meth)acrylates bearing the functional groups. The substances containing epoxy groups can be both aromatic and aliphatic compounds.

[0096] Excellently suitable multifunctional epoxides are oligomers of epichlorohydrin, epoxy ethers of polyhydric alcohols (especially ethylene, propylene, and butylene glycols, polyglycols, thiodiglycols, glycerol, pentaerythritol, sorbitol, polyvinyl alcohol, polyallyl alcohol and the like), epoxy ethers of polyhydric phenols [especially resorcinol, hydroquinone, bis-(4-hydroxyphenyl)methane, bis-(4-hydroxy-3-methylphenyl)methane, bis-(4-hydroxy-3,5-dibromophenyl)methane, bis-(4-hydroxy-3,5-difluorophenyl)methane, 1,1-bis-(4-hydroxyphenyl)ethane, 2,2-bis-(4-hydroxyphenyl)propane, 2,2-bis-(4-hydroxy-3-methylphenyl)propane, 2,2-bis-(4-hydroxy-3-chlorophenyl)propane, 2,2-bis-(4-hydroxy-3,5-dichlorophenyl)-propane, 2,2-bis-(4-hydroxy-3,5-dichlorophenyl)-propane, bis-(4-hydroxyphenyl)-phenylmethane, bis-(4-hydroxyphenyl)-phenylmethane, bis-(4-hydroxyphenyl)-diphenylmethane, bis-(4-hydroxyphenyl)-4'-methylphenylmethane, 1,1-Bis-(4-hydroxyphenyl)-2,2,2-trichloroethane, bis-(4-hydroxyphenyl)-(4-chlorophenyl)-methane, 1,1-bis-(4-hydroxyphenyl)-cyclohexane, bis-(4-hydroxyphenyl)-cyclohexylmethane, 4,4'-dihydroxydiphenyl, 2,2'-dihydroxydiphenyl, 4,4'-dihydroxydiphenylsulfone] and their hydroxyethyl ethers, phenol-formaldehyde condensation products, such as phenol alcohols, phenolaldehyde resins and similar, S- and N-containing epoxides (for example N,N-diglycidylanillin, N,N'-dimethyldiglycidyl-4,4-diaminodiphenylmethane) and epoxides which have been prepared by conventional processes from polyunsaturated carboxylic acids or monounsaturated carboxylic acid residues of unsaturated alcohols, glycidyl esters, polyglycidyl esters which can be obtained by polymerization or copolymerization of glycidyl esters of unsaturated acids or from other acidic compounds (cyanuric acid, Diglycidyl sulfide, cyclic trimethylenetrisulfone or their derivatives and others).

[0097] Very suitable ethers are, for example, 1,4-butanediol diglycidyl ether, polyglycerol-3-glycidyl ether, cyclohexanedimethanol diglycidyl ether, glycerol triglycidyl ether, neopentyl glycol diglycidyl ether, pentaerythritol tetraglycidyl ether, 1,6-hexanediol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, bisphenol A diglycidyl ether and bisphenol F diglycidyl ether.

[0098] Particularly preferred for the poly(meth)acrylates as polymers to be crosslinked is the use of a crosslinker-accelerator system ("crosslinking system"), as described, for example, in EP 1 978 069 A1, in order to obtain better control over both the processing time, crosslinking kinetics, and the degree of crosslinking. The crosslinker-accelerator system comprises at least one substance containing epoxy groups as a crosslinker and at least one substance that accelerates crosslinking reactions using compounds containing epoxy groups at a temperature below the melting temperature of the polymer to be crosslinked.

[0099] According to the invention, amines (formally to be understood as substitution products of ammonia; in the following formulae, these substituents are represented by “R” and include in particular alkyl and / or aryl radicals and / or other organic radicals) are particularly preferably used as accelerators, particularly preferably those amines which do not react or only react slightly with the building blocks of the polymers to be crosslinked.

[0100] In principle, primary (NRH2), secondary (NR2H), and tertiary amines (NR3) can be selected as accelerators, including those containing multiple primary and / or secondary and / or tertiary amine groups. Particularly preferred accelerators, however, are tertiary amines such as triethylamine, triethylenediamine, benzyldimethylamine, dimethylaminomethylphenol, 2,4,6-tris(N,N-dimethylaminomethyl)phenol, and N,N'-bis(3-(dimethylamino)propyl)urea. Multifunctional amines such as diamines, triamines, and / or tetramines can also be used advantageously as accelerators. Diethylenetriamine, triethylenetetramine, and trimethylhexamethylenediamine, for example, are excellently suited.

[0101] Amino alcohols are also preferred as accelerators. Secondary and / or tertiary amino alcohols are particularly preferred, with at least one, preferably all, of the amine functionalities being secondary and / or tertiary in the case of multiple amine functionalities per molecule. Preferred amino alcohol accelerators that can be used are triethanolamine, N,N-bis(2-hydroxypropyl)ethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, 2-aminocyclohexanol, bis(2-hydroxycyclohexyl)methylamine, 2-(diisopropylamino)ethanol, 2-(dibutylamino)ethanol, N-butyldiethanolamine, N-butylethanolamine, 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)-1,3-propanediol, 1-[bis(2-hydroxyethyl)amino]-2-propanol, triisopropanolamine, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 2-(2-dimethylaminoethoxy)ethanol, N,N,N'-trimethyl-N'-hydroxyethylbisaminoethyl ether, N,N,N'-trimethylaminoethylethanolamine and / or N,N,N'-trimethylaminopropylethanolamine.

[0102] Other suitable accelerators include pyridine, imidazoles (such as 2-methylimidazole), and 1,8-diazabicyclo[5.4.0]undec-7-ene. Cycloaliphatic polyamines can also be used as accelerators. Phosphate-based accelerators such as phosphines and / or phosphonium compounds, such as triphenylphosphine or tetraphenylphosphonium tetraphenylborate, are also suitable.

[0103] Acrylic pressure-sensitive adhesives are typically radically polymerized copolymers of acrylic acid alkyl esters or methacrylic acid alkyl esters of C1 to C20 alcohols such as methyl acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, iso-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, tetradecyl (meth)acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate and stearyl (meth)acrylate in addition to other (meth)acrylic acid esters such as isobornyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate and 2-bromoethyl (meth)acrylate. Alkoxyalkyl (meth)acrylates such as ethoxyethyl (meth)acrylate. These also include esters of ethylenically unsaturated di- and tricarboxylic acids and anhydrides such as ethyl maleate, dimethyl fumarate, and ethyl methyl itaconate.Also included are vinyl aromatic monomers such as styrene, vinyltoluene, methylstyrene, n-butylstyrene and decylstyrene.

[0104] Other possible monomers are vinyl esters of carboxylic acids containing up to 20 carbon atoms, such as vinyl acetate or vinyl laurate, vinyl ethers of alcohols containing up to 10 carbon atoms, such as vinyl methyl ether or vinyl isobutyl ether, vinyl halides such as vinyl chloride or vinylidene dichloride, nitriles such as acrylonitrile or methacrylonitrile, acid amides such as acrylamide or methacrylamide, and unsaturated hydrocarbons with 2 to 8 carbon atoms, such as ethylene, propene, butadiene, isoprene, 1-hexene, or 1-octene.

[0105] To influence the physical and optical properties of the pressure-sensitive adhesive, multifunctional ethylenically unsaturated monomers can be used as crosslinking monomers. Examples include divinylbenzene, alkyl diacrylates such as 1,2-ethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, or 1,12-dodecanediol diacrylate, triacrylates such as trimethylolpropane triacrylate, and tetraacrylates such as pentaerythritol tetraacrylate. The group of multifunctional monomers also includes UV-crosslinkable monomers, such as (meth)acrylate-functionalized derivatives of benzophenone or benzoin.

[0106] Another group of monomers are those that generate a latent crosslinking potential in the polymer and, after the adhesive has dried, spontaneously (often catalyzed) lead to network formation. One such monomer is glycidyl methacrylate, whose oxirane ring with hydroxyl or, in particular, carboxylate functions leads to a covalent bond through ring opening. This reaction is accelerated in the presence of zinc ions or, especially in the presence of carboxyl functions, amines.

[0107] To achieve pressure-sensitive adhesive properties, the processing temperature of the adhesive must be above its glass transition temperature in order to have viscoelastic properties.

[0108] Furthermore, activatable adhesives based on acrylate according to the invention can be used. In a particularly preferred embodiment, the activatable adhesives consist of a base polymer a) consisting of a1) 40 to 95 wt.% of acrylic acid esters and / or methacrylic acid esters having the following formula CH2 = C(R1)(COOR2), where R1 = H or CH3 and R2 = H and / or alkyl chains with 1 to 30 C atoms. a2) 5 to 30 wt.% of a copolymerizable vinyl monomer having at least one carboxylic acid and / or sulfonic acid and / or phosphonic acid group a3) 1 to 10 wt.% of a copolymerizable vinyl monomer having at least one epoxy group or one acid anhydride function a4) 0 to 20 wt.% of a copolymerizable vinyl monomer which, with the functional group, can contribute to increasing cohesion, increasing the reactivity of the crosslinking, or to direct crosslinking, and b) 5 to 50 wt.% of an epoxy resin or a mixture of several epoxy resins

[0109] The polymer a) can comprise an activatable pressure-sensitive adhesive that becomes tacky under the influence of temperature and optionally pressure and, after bonding and cooling, builds up a high bond strength through solidification. Depending on the application temperature, these activatable pressure-sensitive adhesives exhibit different static glass transition temperatures T G,A or a melting point T S,A on.

[0110] In a very preferred embodiment, acrylic monomers comprising acrylic and methacrylic acid esters with alkyl groups consisting of 4 to 14 carbon atoms, preferably 4 to 9 carbon atoms, are used for the monomers a1). Specific examples, without wishing to be limited by this list, are n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate, n-nonyl acrylate, lauryl acrylate, stearyl acrylate, behenyl acrylate, and their branched isomers, such as 2-ethylhexyl acrylate. Other classes of compounds that can also be used and added in small amounts under c1) are methyl methacrylates, cyclohexyl methacrylates, isobornyl acrylate, and isobornyl methacrylates.

[0111] In a preferred manner, itaconic acid, acrylic acid, methacrylic acid, vinylacetic acid, fumaric acid, crotonic acid, aconitic acid, dimethylacrylic acid, β-acryloyloxypropionic acid, trichloroacrylic acid, vinylphosphonic acid, vinylsulfonic acid and vinylsulfonic acid are used as monomers a2).

[0112] In a preferred manner, glycidyl methacrylate, maleic anhydride and itaconic anhydride are used as monomers a3).

[0113] In a very preferred embodiment, vinyl esters, vinyl ethers, vinyl halides, vinylidene halides, and vinyl compounds with aromatic rings and heterocycles in the α-position are used for the monomers a4). Some examples, not limited to vinyl acetate, vinylformamide, vinylpyridine, ethyl vinyl ether, vinyl chloride, vinylidene chloride, and acrylonitrile, are also used.

[0114] In a further very preferred embodiment for the monomers a4) monomers with the following functional groups are used: hydroxyl, acid amide, isocyanato or amino groups.

[0115] Further particularly preferred examples of component a4) are hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, allyl alcohol, acrylamide, benzyl acrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate, t-butylphenyl acrylate, t-butylaphenyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, 2-Butoxyethyl methacrylate, 2-butoxyethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, cyanoethyl methacrylate, cyanoethyl acrylate, 6-hydroxyhexyl methacrylate, N-tert-butylacrylamide, N-methylol methacrylamide, N-(buthoxymethyl)methacrylamide, N-methylolacrylamide, N-(ethoxymethyl)acrylamide, N-isopropylacrylamide, Tetrahydrofurfuryl acrylate, although this list is not exhaustive.

[0116] In a further preferred embodiment, aromatic vinyl compounds are used for component a4), wherein the aromatic nuclei preferably consist of C4 to C18 and may also contain heteroatoms. Particularly preferred examples are styrene, 4-vinylpyridine, N-vinylphthalimide, methylstyrene, 3,4-dimethoxystyrene, and 4-vinylbenzoic acid, although this list is not exhaustive.

[0117] For polymerization, the monomers are again selected such that the resulting polymers can be used as industrially usable adhesives or pressure-sensitive adhesives, in particular such that the resulting polymers possess adhesive or pressure-sensitive adhesive properties according to the "Handbook of Pressure Sensitive Adhesive Technology" by Donatas Satas (van Nostrand, New York 1989). Here, too, the desired glass transition temperature can be controlled by applying the Fox equation (G1) when composing the monomer mixture underlying the polymerization. For pressure-sensitive adhesives, the static glass transition temperature of the resulting polymer is advantageously below 15 °C.

[0118] To achieve a glass transition temperature T G,A the polymers of T G,A≥30 °C for heat-activated adhesives, the monomers are very preferably selected in accordance with the above and the quantitative composition of the monomer mixture is advantageously selected such that according to the Fox equation (G1) (cf. TG Fox, Bull. Am. Phys. Soc. 1 (1956) 123) the desired T G,A -value for the polymer. 1TG=∑nwNTG,n

[0119] Here, n represents the number of monomers used, w n the mass fraction of the respective monomer n (wt%) and T G,n the respective glass transition temperature of the homopolymer from the respective monomers n in K.

[0120] Conventional radical polymerizations or controlled radical polymerizations are advantageously carried out to produce the adhesives. For radical polymerizations, initiator systems that additionally contain other radical initiators for polymerization are preferred, in particular thermally decomposing, radical-forming azo or peroxo initiators. In principle, however, all conventional initiators for acrylates familiar to the person skilled in the art are suitable. The production of C-centered radicals is described in Houben-Weyl, Methoden der Organischen Chemie, Vol. E 19a, pages 60 to 147. These methods are preferably applied analogously.

[0121] Examples of radical sources include peroxides, hydroperoxides, and azo compounds. Non-exclusive examples of typical radical initiators include potassium peroxodisulfate, dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-t-butyl peroxide, azodiisobutyronitrile, cyclohexylsulfonylacetyl peroxide, diisopropyl percarbonate, t-butyl peroctoate, and benzpinacol. In a highly preferred embodiment, 1,1'-azobis(cyclohexanecarbonitrile) (Vazo 88™ from DuPont) is used as the radical initiator.

[0122] The average molecular weights M n The molecular weights of the pressure-sensitive adhesives produced during radical polymerization are very preferably selected in a range from 20,000 to 2,000,000 g / mol; especially for further use as hot melt pressure-sensitive adhesives, pressure-sensitive adhesives with average molecular weights M n from 100,000 to 500,000 g / mol.

[0123] The polymerization can be carried out in bulk, in the presence of one or more organic solvents, in the presence of water, or in mixtures of organic solvents and water. The aim is to keep the amount of solvent used as low as possible.

[0124] The polymerization time is between 4 and 72 hours, depending on the conversion and temperature. The higher the reaction temperature, i.e., the higher the thermal stability of the reaction mixture, the shorter the reaction time can be.

[0125] To increase the cohesion between the adhesive and the film, the film can be subjected to a corona treatment. Etching the film is also advantageous for anchoring the adhesive.

[0126] In one variant of the invention, a primer is applied between the lower film and the adhesive to improve the adhesion of the adhesive to the film. Descriptions of commonly used primers can be found, for example, in Donatas Satas' "Handbook of Pressure Sensitive Adhesive Technology" (van Nostrand, 1989).

[0127] Preferably, the upper and lower foils in the die-cut product have the same shape and size and are arranged congruently. Furthermore, these conditions preferably also apply to any additional foils present.

[0128] A typical size for the die cut, which can be used to close many of the smaller holes, is a (circular) disc with a diameter of 10 to 60 mm, in particular 30 to 40 mm.

[0129] Preferably, the lower film is fully coated with the adhesive.

[0130] A method for closing a hole, in particular in a car body, with a punched piece according to the invention is characterized by the following steps: • Apply the die-cut to the hole to be closed in such a way that the hole is completely covered by the die-cut • Exposure to temperatures of 120 °C to 200 °C, especially 175 °C for 15 minutes on the die-cut, so that the heat-activated adhesive hardens and the hole is sealed

[0131] The die-cut product can also withstand temperatures of, for example, 190°C or more for a few minutes, for example if there is a system malfunction and the (automotive) bodies are left in the drying ovens for a longer period of time.

[0132] Preferably, the adhesive cures by applying heat during the usual finishing process of the bodyshell, especially during painting, underbody protection, or cathodic dip drying. This eliminates the need for any additional work steps.

[0133] Due to the necessary heating of the body during the drying processes, sufficient energy is available.

[0134] Alternatively, local energy supply via heat or infrared radiators is possible.

[0135] It is preferable for the die-cut to be applied concentrically over the hole to be sealed. However, it is also possible for the die-cut to be offset to one side. It is important that the adhesive area of ​​the die-cut covers the hole and also a minimum area around the hole.

[0136] Advantageously, the contours of the die-cut product correspond to the contour of the hole to be sealed. This results in a symmetrical overhang of the individual layers of the die-cut product. The overhang is preferably between 1 and 20 mm, more preferably between 5 and 10 mm.

[0137] The die-cut is preferably formed as a circle, although other geometries, such as ovals, rectangles, or squares, are also conceivable; a circular shape is preferred.

[0138] The die-cut according to the invention, thanks to its specially designed grip area, allows for easy removal without damaging or even destroying existing cathodic dip coatings or other paint layers or other coatings. A single embodiment of the die-cut can cover a multitude of holes of different sizes.

[0139] The present invention also relates to a method for closing a hole, in particular in a body, with a punched piece according to the present invention, which comprises the following steps: Applying the die-cut to the hole to be closed in such a way that the hole is completely covered by the adhesive area of ​​the die-cut; Separating the support section of the grip area from the adhesive section; folding the grip area out of the die-cut plane; Folding the support section at the embossing in the form of a second line between the support section and the connecting section in the direction of the connecting section until the support section forms a substantially right angle with the embossing in the form of a first line between the connecting section of the grip area and the adhesive area.

[0140] The die-cut according to the invention can be used to seal any holes, especially those that are only temporarily sealed, i.e., where the best possible, residue-free removal is desired. The die-cut according to the invention is particularly suitable for use in the automotive industry. Test methods

[0141] The measurements are carried out (unless otherwise stated) at a test temperature of 23 ± 1 °C and 50 ± 5 % relative humidity. Molar mass Mn and weight-average molecular mass Mw

[0142] The number-average molar mass Mn and weight-average molar mass Mw values ​​in this document refer to the determination by gel permeation chromatography (GPC). The determination is carried out on 100 µl of a clear-filtered sample (sample concentration 4 g / l). Tetrahydrofuran with 0.1 vol% trifluoroacetic acid is used as the eluent. The measurement is carried out at 25 °C.

[0143] The guard column is a column type PSS-SDV, 5 µm, 10 3 Å, 8.0 mm * 50 mm (information here and below in the order: type, particle size, porosity, inner diameter * length; 1 Å = 10 -10 m) is used. For separation, a combination of columns of type PSS-SDV, 5 µm, 10 3 Å and 10 5 Å and 10 6 Å columns with a diameter of 8.0 mm x 300 mm each were used (columns from Polymer Standards Service; detection using a Shodex RI71 differential refractometer). The flow rate was 1.0 ml per minute. Calibration was performed against PMMA standards (polymethyl methacrylate calibration) for polyacrylates and against PS standards (polystyrene calibration) for other materials (resins, elastomers).

[0144] The polyacrylates preferably have a K value of 30 to 90, particularly preferably 40 to 70, measured in toluene (1% solution, 21°C). The Fikentscher K value is a measure of the molecular weight and viscosity of the polymer. K-value

[0145] The principle of the method is based on the capillary viscometric determination of the relative solution viscosity. For this purpose, the test substance is dissolved in toluene by shaking for 30 minutes to obtain a 1% solution. The flow time is measured in a Vogel-Ossag viscometer at 25 °C, and the relative viscosity of the sample solution is determined from this in relation to the viscosity of the pure solvent. The K value can be read from tables according to Fikentscher [PE Hinkamp, ​​Polymer, 1967, 8, 381] (K = 1000 k). Glass transition temperature

[0146] The glass transition temperature is determined using dynamic scanning calorimetry (DSC). For this purpose, 5 mg of an untreated polymer sample is weighed into an aluminum crucible (volume 25 µL) and sealed with a perforated lid. A Netzsch DSC 204 F1 is used for the measurement. The measurement is carried out under nitrogen for inerting. The sample is first cooled to -150 °C, then heated at a heating rate of 10 K / min to +150 °C and cooled again to -150 °C. The subsequent second heating curve is run again at 10 K / min, and the change in heat capacity is recorded. Glass transitions are detected as steps in the thermogram.

[0147] In the following, an embodiment of the punched part for temporarily closing holes, particularly in sheet metal or in plastic parts of automobile bodies, will be explained in more detail without being intended to be restrictive in any way.

[0148] It shows Fig. 1 shows the product structure of an embodiment according to the invention in cross section; Fig. 2 the product structure of a die-cut product of the state of the art; Fig. 3 is a plan view of an embodiment of the invention; Fig. 4 is a plan view of a prior art die-cut applied to a hole; Fig. 5 is a plan view of a die-cut according to the invention applied to a hole before folding; Fig. 6 a perspective view of a die-cut according to the invention applied to a hole after folding; Fig. 7 a plan view of a die-cut according to the invention applied to a hole after folding.

[0149] There is a hole 10 in the body 1 that needs to be closed.

[0150] For this purpose, a die cut 2, the structure of which is Fig. 1, with a carrier made of a laminate of at least one carrier 4, an adhesive 5 and a cover layer 6 fixed on a hole 10 in such a way that the hole is completely covered by the die-cut, namely by the adhesive area 9 of the die-cut, in which the adhesive surface 5 is not deactivated by the cover layer 6.

[0151] While in a state-of-the-art die-cut, as in Fig. 4, it must only be ensured that the area of ​​the punched piece 2 is larger than the area of ​​the hole 10 to be closed, in a punched piece 2 according to the invention, as shown in Fig. 5, it should be noted that the adhesive area 9 of the die-cut covers the hole, i.e. is larger than the area of ​​the hole 10.

[0152] The die-cut 2 consists of an adhesive area 9 and a grip area 3. The grip area 3 is separated from the adhesive area 9 by an embossing in the form of a first line (first embossing line) 7a and a punching line 8. The grip area 3 is divided into a connecting section 3a and a supporting section 3b by an embossing in the form of a second line (second embossing line) 7b.

[0153] During application, the die-cut 2 is first glued over the hole 10, as explained above, in such a way that the adhesive area 9 of the die-cut 2 completely covers it. In a next step, the support section 3b of the grip area 3 is detached from the adhesive section at the perforation 8. The entire grip area 3 is then folded upwards or in the direction of the adhesive area 9 until an angle of approximately 90° is reached. In a next step, the support section 3b is folded in the direction of the connecting section 3a until an angle of approximately 90° is reached with respect to the embossing in the form of a first line 7a or perforation in the form of a line 8, as shown in Fig. 6 and Fig. 7. Connecting section 3a and support section 3b now form a handle that allows easy removal of the entire die-cut 2.

Claims

[1] Die-cut (2), in particular for temporarily closing holes (10), in particular in sheet metal or in plastic parts, consisting of a carrier (4), the carrier being coated on one side with an adhesive (5), in particular a curable or self-adhesive adhesive, wherein the die-cut (2) has an adhesive area (9) and a grip area (3), wherein the grip area (3) is located in the delivery state with the adhesive area (9) in one plane, the die-cut plane, wherein the grip area (3) is not adhesive, characterized by that the grip area (3) consists of two sections (3a, 3b), a connecting section (3a) and a supporting section (3b), wherein the connecting section (3a) is connected to the adhesive area (9) of the die-cut (2) and, in the applied state, is inclined by an angle α from the die-cut plane and wherein the support section (3b) in the applied state is only connected to the connecting section (3a) and ensures the inclination of the connecting section (3a) from the die-cut plane. [2] Die-cut (2) according to claim 1, characterized by that the carrier (4) is coated with adhesive (5) over its entire surface and a cover layer (6) is applied to the adhesive (5) in the grip area (3). [3] Die-cut (2) according to claim 1, characterized by that the carrier (4) is coated with adhesive (5) only in the adhesive area (9) and no adhesive is applied in the grip area (3). [4] Die-cut (2) according to one of claims 1 to 3, characterized by that an embossing in the form of a first line (7a) is provided between the connecting section (3a) of the grip area (3) and the adhesive area (9). [5] Die-cut (2) according to one of claims 1 to 4, characterized bythat an embossing in the form of a second line (7b) is provided between the connecting section (3a) and the support section (3b) of the grip area (3). [6] Die-cut (2) according to one of the preceding claims, characterized by that in the delivery state the support section (3b) of the grip area (3) is connected to the adhesive area (9) by a perforation in the form of a line (8). [7] Die-cut (2) according to one of the preceding claims, characterized by that an acrylate-based self-adhesive is chosen as the adhesive (5). [8] Die-cut (2) according to one of the preceding claims, characterized by that a reactive heat-activatable adhesive, in particular made of nitrile rubber and phenolic resin, is selected as the adhesive (5). [9] Method for closing a hole (10), in particular in a body, with a punched piece (2) according to one of the preceding claims in conjunction with claims 4 and 5, characterized by following steps: Applying the die-cut (2) to the hole (10) to be closed in such a way that the hole (10) is completely covered by the adhesive area (9) of the die-cut (2); Separating the support section (3b) of the grip area (3) from the adhesive area (9); Folding out the grip area (3) from the die-cutting plane; Folding the support section (3b) at the embossing in the form of a second line (7b) between the support section (3b) and the connecting section (3a) in the direction of the connecting section (3a) until the support section (3b) forms a right angle with the embossing in the form of a first line (7a) between the connecting section (3a) of the grip area (3) and the adhesive area (9). [10] Method according to claim 9, characterized by that the punched piece (2) is applied concentrically over the hole (10) to be closed. [11] Method according to claim 9 or 10, characterized bythat the contours of the punched piece (2) correspond to the contour of the hole (10) to be closed, so that a symmetrical projection of the punched piece results. [12] Use of a punched piece (2) according to one of claims 1 to 8 for temporarily closing a hole (10) in an automobile body.

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