Use of adhesive tape for masking during the painting of automobile bodies and components

Abstract

Use of an adhesive tape for masking during the painting of automobile bodies and components, wherein the adhesive tape has a web-shaped carrier material and a coating of an adhesive applied at least on one side thereof, wherein the adhesive comprises a composition of at least one polyisobutylene (A) with a weight-average molecular weight M w from 30,000 to 800,000 g / mol, consisting of at least one polyisobutylene (B) with a weight-average molecular weight M w from 1,000,000 to 5,000,000 g / mol and at least one adhesive resin (C), selected from the group of terpene resins, aliphatic, cycloaliphatic, aromatic and mixed hydrocarbon resins, the composition having a mixing ratio of • (A) 25 to 35 wt.% • (B) 40 to 50 wt.% and • (C) 15 to 30 wt.% exhibits and wherein the sum of the shares of (A), (B) and (C) equals 100 wt.%.

Description

[0001] The present invention relates to the use of an adhesive tape for temporarily covering (masking) surfaces before further processing such as sandblasting or painting and for creating structures such as straight lines or curved lines, letters or logos in the painting of automobile bodies and components.

[0002] A self-adhesive masking tape, hereinafter also referred to as masking tape, should possess several essential properties to meet the specific requirements placed on the tape. Slight elasticity when applying tape to curves (i.e., a not excessively high maximum or tensile strength) combined with a high modulus of elasticity (estimated by the force at 1% elongation) in the range of forces occurring during unwinding or application on straight sections, no or minimal shrinkage tendency when bonded, and a low thickness are key requirements for creating a sharp and uniform paint edge on flat and curved surfaces, as well as for ensuring clean bonding in curves.

[0003] Up to now, masking tapes with a paper or film backing have been used for this application. Paper-based masking tapes generally have no negative impact on the surface being masked or on the paint layer being applied.

[0004] Users typically desire easy tearing by hand during application to ensure quick and easy processing of the masking tape. A masking tape is specifically expected not to adversely affect (damage) either the surface to which it is being masked or the paint layer being applied. This means, in particular, that the surface should show no discoloration, mechanical deformation, or residue from the masking tape (i.e., from the adhesive or film) after removal, as the function of a masking tape is precisely to protect the surface.

[0005] Masking tapes with a stack of masking film are also well known in the prior art.

[0006] From EP 1 149 883 B1, a masking tape is known, comprising an adhesive tape with a paper backing containing a self-adhesive layer. In the edge region of the self-adhesive layer, a masking material with good paint adhesion is laminated, and in the same edge region of the self-adhesive layer, a masking film is laminated, completely covering and backing the masking material. The masking tape exhibits good adhesion for paint, which therefore does not flake off even after oven drying. The masking tape is particularly suitable for masking areas not to be painted during automotive refinishing.

[0007] EP 1 149 634 B1 discloses a masking tape made of a temperature-resistant adhesive tape with a flexible film carrier and a self-adhesive backing. A masking material exhibiting good paint adhesion and absorbency is laminated to the edge of the self-adhesive backing. A masking film laminated to the same paint edge area also backs the masking material when applied. In contrast to the first-mentioned publication, this one discloses a masking material with good paint adhesion and absorbency in general. This masking tape is also suitable for marking areas to be left unpainted during the painting of automobiles.

[0008] The masking film is usually very wide, and is therefore folded and stacked next to the adhesive tape. The masking tape is typically supplied in rolls.

[0009] Adhesive films used for the temporary protection of surfaces can, for example, interact with the surface in such a way that the adhesion increases undesirably. A surface might be highly polar, for instance, and thus interact strongly with the adhesive in an attractive way.

[0010] Prolonged bonding times, especially at higher temperatures, can significantly increase the adhesive strength. Subsequent removal of the adhesive films requires considerable force, and adhesive residue can detach from the backing and remain on the surface.

[0011] Such problems are often observed with acrylate-based adhesives that initially exhibit insufficient adhesive strength and "lift" over time. Additionally, after removing the masking tape, a so-called "ghosting" effect can remain on the surface – undefined residues that leave a haze (particularly visible on dark surfaces).

[0012] For the purposes of this invention, ghosting is understood to mean that non-sticky but visually perceptible residues are detectable on the previously bonded surface when viewed at a shallow angle against a light source. Ghosting is particularly noticeable on dark painted surfaces.

[0013] In this context, "ghosting" or "ghost image" typically refers to very thin, non-sticky coatings or deposits on a surface that cause optical changes to the surface that are visible to the naked eye. These coatings or deposits are caused by a covering material that was previously in contact with the surface. The coatings are often not even wipeable, but are visually perceptible when viewed at a shallow angle against a light source. Ghosting is particularly noticeable on dark painted surfaces. Further details on the phenomenon of "ghosting" are described in US 2002 / 098353 A1.

[0014] When bonding to painted surfaces, surface deformation is also undesirable. Deformations are visually recognizable changes to a painted surface that occur when fresh, not fully cured paint is covered with an unsuitable protective film. Such deformations can be caused by impressions and can occur across the entire bonded area or only at the bonded edges. These deformations are recognizable, for example, as a matting effect, as described in DE 100 63 661 A1, which also proposes a solution to this problem.

[0015] Synthetic rubber-based adhesives exhibit significantly more consistent adhesive strength over the bonding period. However, synthetic rubber adhesives become very soft when heated and lose internal cohesion. When used as masking tape in painting applications, the adhesive film is often removed at higher temperatures (50 to 80 °C), meaning that despite ideal adhesive strength, synthetic rubber adhesives can still leave residue and / or ghosting on the surface. Therefore, synthetic rubber adhesives are not typically used as masking tapes with high temperature requirements. A qualified expert in the painting industry would always advise against using synthetic rubber adhesives for such applications.

[0016] Adhesive films with natural rubber adhesives are typically used for masking applications. These films exhibit consistent adhesive strength throughout the bonding time and also possess sufficient internal cohesion at higher temperatures. However, they are not suitable for application temperatures above approximately 160 °C because they become increasingly brittle and leave residues and / or ghosting. In particular, after removal of the adhesive film from surfaces protected by such high temperatures, yellowing occurs, which is clearly visible, especially on light (white) surfaces, and therefore unacceptable for design and aesthetic reasons.

[0017] Silicone-based adhesives are often used for high-temperature applications. Nevertheless, yellowing of paints is frequently observed; in particular, silicone contamination of the environment can lead to defects in paint film formation, visible as craters or blisters in the paint, reduced paint adhesion, and consequently, subsequent paint peeling and other damage.

[0018] Polyisobutylene as a basic material for adhesives is generally known and is also described as such in the literature.

[0019] The BASF Oppanol brochure (version EVO1545, 07-2015) discloses its use as an adhesive for transport protection films.

[0020] The brochure “X-butyl regular butyl rubber” by Arlanxeo (09-2018) shows an undefined formulation with polyisobutylene for sealants; its application or suitability as a masking compound is neither indicated nor suggested.

[0021] The "Handbook of pressure-sensitive adhesives and products" (2008, CRC Press, Chapter 4: Polyisobutene-based pressure-sensitive adhesives) also describes a PIB formulation based on a high-molecular-weight PIB with three different resins in high proportions. This formulation is unsuitable for temperature masking because residues are to be expected due to the very high proportion of low-molecular-weight resins, as well as yellowing due to the carbon double bonds in the resins.

[0022] DE 103 57 321 A1 discloses a high-tack adhesive containing at least a) polyisobutylene and b) at least one tackifying resin, characterized in that c) the molecular weight distribution - i.e., the diagrammatic representation of the frequency versus the molecular weight - of the polyisobutylene has two relative maxima, d) namely one between 50,000 and 200,000 and e) a second between 1.0 * 10 6 and 3.5 * 10 6 .

[0023] US 2012 / 0118469 A1 discloses adhesive compositions described which contain a) a non-functional isobutylene(co)polymer, b) an amine-functional poly(isobutylene)polymer, optionally an acid-functional (meth)acrylate copolymer and optionally a tackifier.

[0024] From US patent 2013 / 0324651 A1, an adhesive composition is known comprising at least a first isobutylene polymer having an average molecular weight of at least 750,000 g / mol and at least a second polyisobutylene polymer having an average molecular weight of at least 100,000 g / mol and less than 500,000 g / mol; and an alkylamine adhesion promoter; wherein the alkylamine is unreactive with respect to the isobutylene polymer.

[0025] DE 20 46 189 A describes a sealing compound with a PIB having a molecular weight M w from 300 to 50,000 g / mol and a second PIB with a molecular weight Mw from 300,000 to 2,000,000 g / mol and a filler with a proportion of 20 to 85 wt.%. The sealant does not have the properties of an adhesive (no tack, hardly any adhesive strength) and is therefore not suitable in a masking film for paint protection.

[0026] DE 197 16 712 A describes a fabric tape with an adhesive made of two polyisobutylenes with molecular weights M w between 5,000 and 100,000 g / mol and DE 692 32 430 T an adhesive film for transport protection with an adhesive mass made of two polyisobutylenes with molecular weights M w of 35,000 and 1,200,000. Both adhesive tapes are used for transport protection. They are not suitable for masking films due to insufficient cohesion under heat.

[0027] Polyisobutylene adhesives for splice tape applications are known from WO 2005 / 054392 A1. The disclosed adhesive formulations have a very high proportion of low-molecular-weight polyisobutylene and recommend high amounts of resins and oils as plasticizers. The stated adhesive strengths are too high for masking applications, and the high proportion of low-molecular-weight and oil components leads to low cohesion at high temperatures.

[0028] Therefore, there is a need for an adhesive compound with a reasonably constant adhesive strength over the bonding time, which is temperature-stable with regard to automotive painting processes (for example, one hour at 170 °C), which can be removed without residue at elevated temperatures and which does not cause any changes to the bonded (paint) surface, in particular no yellowing.

[0029] The object of the invention is to provide an adhesive tape for masking during the painting of automobile bodies and components, wherein the adhesive tape has a web-shaped carrier material and a coating of an adhesive applied at least on one side, which, in addition to fulfilling the aforementioned requirements, in particular causes no adhesive residue, no ghosting and no visible "yellowing" when the adhesive tape with the adhesive on the paint layer to be protected is subjected to thermal stress in the paint oven and then peeled off at room temperature.

[0030] This problem is solved by using an adhesive tape as described in the main claim. The dependent claims relate to advantageous embodiments of the invention.

[0031] Accordingly, the invention describes the use of an adhesive tape for masking during the painting of automobile bodies and components, wherein the adhesive tape has a web-shaped carrier material and a coating of an adhesive applied at least on one side thereof, wherein the adhesive comprises a composition of at least one polyisobutylene (A) with a weight-average molecular weight M w from 30,000 to 800,000 g / mol, consisting of at least one polyisobutylene (B) with a weight-average molecular weight M w from 1,000,000 to 5,000,000 g / mol and at least one adhesive resin (C) selected from the group of terpene resins, aliphatic, cycloaliphatic, aromatic and mixed hydrocarbon resins, the composition having a mixing ratio of • (A) 25 to 35 wt.% • (B) 40 to 50 wt.% and • (C) 15 to 30 wt.% exhibits and wherein the sum of the shares of (A), (B) and (C) equals 100 wt.%.

[0032] According to the invention, an adhesive compound or pressure-sensitive adhesive is understood, as is common in general usage, to be a substance that is permanently sticky and adhesive, at least at room temperature. A characteristic of a pressure-sensitive adhesive is that it can be applied to a substrate by pressure and adheres there, whereby the pressure to be applied and the duration of this pressure are not defined in detail. Generally, however, depending on the exact type of pressure-sensitive adhesive and the substrate, as well as the temperature and humidity, the application of a short-term, minimal pressure, not exceeding a light touch for a brief moment, is sufficient to achieve the adhesive effect; in other cases, a longer duration of higher pressure may be necessary.

[0033] Pressure-sensitive adhesives possess special, characteristic viscoelastic properties that result in their permanent tackiness and bonding strength. A defining characteristic is that when mechanically deformed, both viscous flow processes and the development of elastic restoring forces occur. The relative proportions of these two processes depend on the precise composition, structure, and degree of cross-linking of the pressure-sensitive adhesive, as well as the rate and duration of deformation and the temperature.

[0034] The proportion of viscous flow is necessary to achieve adhesion. Only the viscous components, often caused by macromolecules with relatively high mobility, enable good wetting and flow onto the substrate to be bonded. A high proportion of viscous flow leads to high tack (also known as surface tack) and thus often also to high adhesion. Highly cross-linked systems, crystalline or glassy polymers, are generally not tacky or at least only slightly tacky due to a lack of flowable components.

[0035] The elastic restoring forces are necessary to achieve cohesion. They are generated, for example, by very long-chain and highly entangled macromolecules, as well as by physically or chemically cross-linked macromolecules, and enable the transmission of forces acting on an adhesive bond. This allows an adhesive bond to withstand a sustained load, such as continuous shear stress, to a sufficient degree over an extended period.

[0036] To describe and quantify the degree of elastic and viscous components, as well as their ratio, the storage modulus (G') and loss modulus (G''), which can be determined using Dynamic Mechanical Analysis (DMA), are used. G' is a measure of the elastic component, and G'' is a measure of the viscous component of a material. Both quantities depend on the deformation frequency and the temperature.

[0037] The parameters can be determined using a rheometer. The material under investigation is subjected, for example, to a sinusoidally oscillating shear stress in a plate-plate arrangement. In shear-stress controlled devices, the deformation is measured as a function of time, along with the time lag of this deformation relative to the application of the shear stress. This time lag is called the phase angle δ.

[0038] The storage modulus G' is defined as follows: G' = (τ / γ) · cos(δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between the shear stress and deformation vectors). The definition of the loss modulus G'' is: G'' = (τ / γ) · sin(δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between the shear stress and deformation vectors).

[0039] A mass is considered to be an adhesive mass, and is defined as such within the meaning of the invention, particularly if it exhibits a deformation frequency of 10°C at 23°C. 0 up to 10 1 rad / sec both G' and G'' at least partially in the range of 10 3 up to 10 7 Pa lie. “Partly” means that at least a section of the G' curve lies within the window defined by the deformation frequency range including 10 0 up to and including 10 1 rad / sec (abscissa) and the range of G' values ​​including 10 3 up to and including 10 7 Pa (ordinate) is spanned, and if at least one section of the G'' curve also lies within the corresponding window.

[0040] Tack (also known as touch tack or finger tack) describes the property of an adhesive to adhere to the substrate under low pressure and short contact times. Shear strength is a measure of the adhesive's resistance to mechanical stress (tension or compression). Adhesive strength (adhesion), in turn, refers to the bonding forces between the adhesive layer and the substrate, as they develop over time. High adhesion results in strong bonding forces.

[0041] Polyisobutylenes are homopolymers of isobutene and are inherently relatively insensitive to light because they contain no unsaturated bonds. Polyisobutylenes are commercially available in numerous molecular weights. Typically, polyisobutylenes with weight-average molar masses starting at M w Molar masses from 1000 g / mol up to over 5,000,000 g / mol are offered. These have a weight-average molar mass of approximately M. wAt a molecular weight of 200,000 g / mol, polyisobutylenes are liquid at room temperature; above this weight, they have a rubber-like consistency. In the latter case, they can be granulated into a readily processable form.

[0042] The term polyisobutylene also includes a copolymer whose monomer base consists of at least 50 wt%, preferably more than 50 wt%, isobutylene. Comonomers can be ethylene, propylene, longer-chain α-olefins, and also polyunsaturated monomers such as isoprene.

[0043] Examples of commercially available polyisobutylenes include BASF's "Oppanol" series. Examples of polyisobutylene-isoprene copolymers include Arlanxeo's "X-butyl regular butyl rubber" series.

[0044] According to a further advantageous embodiment of the invention, the at least one polyisobutylene (A) has a weight-average molecular weight M w from 35,000 to 200,000 g / mol.

[0045] According to a further advantageous embodiment of the invention, the at least one polyisobutylene (B) has a weight-average molecular weight M w from 1,000,000 to 2,500,000 g / mol.

[0046] Preferably, the polyisobutylenes (A) and polyisobutylenes (B) identified as advantageous are used in combination, particularly in the composition of the pressure-sensitive adhesive described above as advantageous.

[0047] The term "tackifier resin" refers to a resin-based substance that increases stickiness.

[0048] According to the invention, the adhesive resin (C) is selected from the group consisting of terpene resins, aliphatic, cycloaliphatic, aromatic and mixed hydrocarbon resins. The resin types mentioned can be partially or fully hydrogenated.

[0049] The resins used according to the invention have the lowest possible proportion of carbon double bonds and a minimum compatibility with polyisobutylene. Examples include the aforementioned terpenes, aliphatic, cycloaliphatic, aromatic and mixed hydrocarbons.

[0050] Particularly suitable are, among others, hydrogenated polymers of dicyclopentadiene (for example, Escorez 5300 series; Exxon Chemicals), hydrogenated polymers of preferably C8 and C9 aromatics (for example, Regalite and Regalrez series; Eastman Inc. or Arkon P series; Arakawa). These can be obtained by hydrogenation of polymers from pure aromatic streams or by hydrogenation of polymers based on mixtures of different aromatics. Also suitable are partially hydrogenated polymers of C8 and C9 aromatics (for example, Regalite and Regalrez series; Eastman Inc. or Arkon M; Arakawa), hydrogenated polyterpene resins (for example, Clearon M; Yasuhara), hydrogenated C5 / C9 polymers (for example, ECR-373; Exxon Chemicals), and aromatic-modified selectively hydrogenated dicyclopentadiene derivatives (for example, Escorez 5600 series; Exxon Chemicals). The aforementioned adhesive resins can be used alone or in mixtures.

[0051] Hydrogenated hydrocarbon resins are particularly suitable due to the absence of double bonds.

[0052] In addition, non-hydrogenated resins can also be used.

[0053] Under these conditions, terpene resins based on α-pinene (Piccolyte A-series from Hercules, Dercolyte A-series from DRT) are particularly preferred, as they offer not only high cohesion but also very high adhesion, even at high temperatures. Terpene resins made from raw materials such as β-pinene and / or δ-limonene are also suitable.

[0054] Furthermore, other polymers can be added to the composition, for example, natural rubber, polybutadiene, or styrene block copolymers. Preferably, their proportion, based on 100 parts by weight of the composition (A), (B), and (C), does not exceed 100, preferably not 75, more preferably not 50, particularly preferably not 25, and particularly preferably not 10 parts by weight.

[0055] Natural rubber or natural rubbers can be of any available quality, such as crepe, RSS, ADS, TSR or CV types, depending on the required purity and viscosity level, and synthetic rubber or synthetic rubbers can be of the statistically copolymerized styrene-butadiene rubbers (SBR), butadiene rubbers (BR), butyl rubbers (IIR), halogenated butyl rubbers (XIIR), acrylate rubbers (ACM), ethylene-vinyl acetate copolymers (EVA) and polyurethanes and / or their blends.

[0056] Furthermore, thermoplastic elastomers may preferably be added. Particularly noteworthy examples are the especially biocompatible styrene-isoprene-styrene (SIS) and styrene-butadiene-styrene (SBS) types.

[0057] Furthermore, they may contain • Up to 5 parts by weight of anti-aging agents (antiozonants, antioxidants) and light stabilizers such as UV stabilizers, for example butylhydroxytoluene (BHT) • up to 10 parts by weight of fillers, in particular inorganic fillers such as TiO2, magnesium sulfate, pigments, plasticizers such as mineral oils, phthalates, fats and fatty acids, white oils, paraffin oils, low molecular weight polybutenes and polyisobutylenes (each with a weight-average molecular weight M w < 2500 g / mol) • up to 2 parts by weight of grading agents such as talc and / or • up to 35 parts by weight flame retardant

[0058] Suitable fillers and pigments include, for example, fibers, carbon black, zinc oxide, titanium dioxide, micro solid spheres, solid or hollow glass spheres, silica, silicates, chalk, carbon black, titanium dioxide, calcium carbonate and / or zinc carbonate.

[0059] Suitable anti-aging agents (antiozonants, antioxidants) are primary antioxidants such as sterically hindered phenols, secondary antioxidants such as phosphites or thiosynergists (thioethers) and / or light protectants such as UV absorbers or sterically hindered amines.

[0060] Suitable plasticizers include, for example, aliphatic, cycloaliphatic and aromatic mineral oils, di- or poly-esters of phthalic acid, trimellitic acid or adipic acid, liquid polymers of butene, acrylic acid esters, and polyvinyl ethers.

[0061] The listed additives are not mandatory; the adhesive compound also works without them being added individually or in any combination.

[0062] The substrate material can be coated with the adhesive on one or both sides. In the double-sided version, only one of the two adhesives needs to be of the type described in claim 1.

[0063] The carrier material preferably has a thickness of 20 to 100 µm, preferably 30 to 60 µm.

[0064] The backing materials used for the adhesive tape are those familiar and common to those skilled in the art, such as paper, creped paper, or films made of, for example, polyesters like polyethylene terephthalate (PET), polyolefins like polyethylene, polypropylene, expanded polypropylene, or polyvinyl chloride. Polybutylene terephthalate (PBT) and polyamide (PA) are also used. Films made of polymers, blends, and composite laminates are also possible.

[0065] Carrier materials made from renewable raw materials such as films made from, for example, polylactic acid, cellulose, modified starch, polyhydroxyalkanoate can also be used.

[0066] Films made of PET and polypropylene are particularly preferred.

[0067] PET has proven its worth for sharp paint edges and high temperature resistance of, for example, 170 °C.

[0068] Films made of polyvinyl chloride are less preferred because yellowing effects are possible.

[0069] Polyolefins typically used include polyethylene, polypropylene, and their mixtures or copolymers (for example, random copolymer or polypropylene block copolymer), or copolymers of ethylene and α-olefins such as 1-butene, 1-hexene, 1-octene (called LLDPE, VLDPE, ULDPE, or metallocene-PE depending on the proportion and manufacturing process), but also ethylene-styrene copolymers, ethylene with polar comonomers such as vinyl acetate, acrylic acid, methacrylic acid, or their salts (ionomers), and copolymers of propylene with α-olefins such as ethylene, 1-butene, 1-hexene, or 1-octene.

[0070] The films can be opaque or translucent and are preferably not colorless.

[0071] While transparency is desirable in some cases, there are instances where opacity or even complete light impermeability is required for visibility or to block light. In these cases, the substrate can be filled with opaque fillers such as titanium dioxide or carbon black, or with a dye. This ensures increased opacity, further improves the light stability of the substrate, and provides a color contrast with the adhesive surface.

[0072] The adhesive has a sufficient minimum adhesion to the substrate; in particular, when unmasking at elevated temperatures (50 to 80 °C), the adhesive does not detach completely or partially from the substrate.

[0073] Advantageous for anchoring the adhesive to the substrate is a pretreatment of the substrate via corona or etching process or the use of an adhesion promoter, a so-called primer layer, between the substrate and the adhesive.

[0074] The carrier material is particularly favored for corona treatment.

[0075] In principle, all well-known dispersion and solvent-based primers can be used, for example, those based on isoprene- or butadiene-containing rubber, acrylate rubber, polyvinyl, polyvinylidene, and / or cyclorubber. Isocyanates or epoxy resins as additives improve adhesion and, in some cases, also increase the shear strength of the pressure-sensitive adhesive. The adhesion promoter can also be applied to the carrier film by means of a co-extrusion layer. Suitable physical surface treatments include, for example, flame treatment, corona or plasma treatment, or co-extrusion layers.

[0076] Etching can be carried out with chromic acid, trichloroacetic acid, trifluoroacetic acid or hydrogen fluoride.

[0077] When a film with adhesive on one side is wound up, the adhesive comes into contact with the back of the carrier of the underlying winding and establishes a certain degree of adhesion. To facilitate unwinding in application, the unwinding force can be reduced and adjusted by applying a release agent to the carrier side facing away from the adhesive.

[0078] This backcoat can be equipped with silicone or fluorosilicone compounds as well as with polyvinylstearylcarbamate, polyethyleneiminstearylcarbamide or fluoroorganic compounds as adhesive (anti-adhesive) substances.

[0079] Suitable release agents include surfactant release systems based on long-chain alkyl groups such as stearyl sulfosuccinates or stearyl sulfosuccinamates, but also polymers that can be selected from the group consisting of polyvinyl stearyl carbamates, polyethyleneimine stearyl carbamates, chromium complexes of C 14 - to C 28 Fatty acids and stearyl copolymers, as described, for example, in DE 28 45 541 A, are suitable. Release agents based on acrylic polymers with perfluorinated alkyl groups, silicones, or fluorosilicone compounds, for example, based on poly(dimethylsiloxanes), are also suitable. Examples of such silicone-based release agents include polyurethane- and / or polyurea-modified silicones.

[0080] Such release agents are based, for example, on silicone, carbamate, acrylate, or fluorine. Carbamate-based release agents such as PVSC, PVODC, and PEIODC are preferred, with PVSC being particularly desirable.

[0081] The coating thickness with adhesive is preferably in the range of 10 to 100 g / m². 2 , especially 10 to 40 g / m² 2 , preferably in the range of 20 to 30 g / m² 2 .

[0082] The adhesive tape can be manufactured using conventional coating processes known to those skilled in the art, by applying the adhesive compound partially or completely to the substrate. The adhesive compound can be dissolved in a suitable solvent and coated onto a carrier film or release liner using, for example, anilox roller coating, doctor blade coating, multi-roller coating, or a printing process. The solvent is then removed in a drying tunnel or oven.

[0083] The coating can also be applied in the form of one or more strips in the longitudinal direction (machine direction), optionally in the transverse direction, but it is primarily applied across the entire surface. Furthermore, the adhesive can be applied in a dot pattern using screen printing, whereby the adhesive dots can also be of varying sizes and / or distributions, by intaglio printing in longitudinal and transverse directions, by halftone printing, or by flexographic printing. The adhesive can be in dome form (produced by screen printing) or in other patterns such as grids, stripes, or zigzag lines. It can also be sprayed on, resulting in a more or less irregular application pattern. Finally, the adhesive can be coated onto a release liner and then bonded to the substrate using a laminating process.

[0084] For the purposes of this invention, the general term "adhesive tape" includes all planar structures whose dimensions in two spatial directions (x-direction and y-direction; length and width) are significantly greater than in the third spatial direction (z-direction; thickness), such as films or film sections, tapes with extended length and limited width, tape sections, die-cut pieces, labels and the like.

[0085] The adhesive tape can be supplied in fixed lengths, such as by the meter, or as continuous material on rolls (Archimedean spiral), i.e., disc-shaped adhesive tape rolls, which are referred to in technical terms as "pancakes".

[0086] Alternatively, the adhesive tape can be wound onto a core, similar to a textile yarn, whose length is significantly greater than the width of the tape. By superimposing a rotational movement of the core and an axial movement of the core or the tape guide element, the tape initially forms a first, radially innermost layer of helical turns. At the end of the first layer and the transition to the second layer, the orientation of the axial movement is inverted while the rotational movement remains unchanged. At the end of the second layer and the transition to the third layer, the orientation of the axial movement is inverted again, thus reverting to the original orientation, while the rotational movement remains unchanged. The pitch angle remains constant between each of these orientation reversal points. In this way, numerous layers of turns can be formed, with each turn intersecting the others (cross-wound coils).

[0087] The adhesive tapes are preferably used in widths of 9 to 50 mm, in particular 19 to 25 mm, and have a preferred thickness of 40 to 200 µm, preferably 50 to 180 µm, and more preferably 55 to 120 µm.

[0088] The widths of the rollers are usually chosen to be 10, 15, 19, 25 and 30 mm.

[0089] Furthermore, the substrate material can be pre- or post-treated. Common pre-treatments include hydrophobing, while common post-treatments include calendering, tempering, laminating, die-cutting, and covering.

[0090] The adhesive tape may also be laminated with a commercially available release film or paper, which is usually made from a base material of polyethylene, polypropylene, polyester or paper coated on one or both sides with polysiloxane.

[0091] Experts know such covering materials as release liners or liners.

[0092] A liner (release paper, release film) is not a component of an adhesive tape, but merely an aid in its manufacture, storage, or further processing by die-cutting. Furthermore, unlike an adhesive tape backing, a liner is not permanently bonded to an adhesive layer.

[0093] The adhesive tape is used for masking during painting, specifically on car bodies and components to create sharp paint edges.

[0094] The adhesive is particularly well-suited for use on sheet metal coated with BASF ProGloss clearcoat. However, the invention is not limited to this coating system, but also works on other clearcoat systems, such as Supermar from Axalta, BASF iGloss and BASF EverGloss, as well as CeramiClear and ApO from PPG, and other automotive clearcoats.

[0095] A particularly advantageous embodiment is one in which a coating of the adhesive is applied to one side of the web-shaped carrier material, wherein a covering material is applied, preferably laminated, in an edge area of ​​the coating extending in the longitudinal direction of the web-shaped carrier material, which extends over the longitudinal edge of the web-shaped carrier material.

[0096] The release liner can alternatively be fixed to the side of the adhesive tape opposite the adhesive side. Fixing preferably refers to laminating, but the release liner can also be welded, heat-sealed, glued, or otherwise secured.

[0097] The protective sheeting typically has a rectangular outer circumference with a length many times greater than its width, and a width many times greater than the thickness of the sheeting. The length of the protective sheeting can, in principle, be infinite, or at least several meters; however, the width can also range from a few centimeters or decimeters to several meters. To make such protective sheets manageable, they are folded into a stack.

[0098] Preferably, the cover film is folded in an accordion fold, and an outer double layer is placed around the accordion stack in at least a U-shape. The U-shaped enclosure of the accordion stack by the outer double layer keeps the cover film stack closed and makes it easier to use.

[0099] In another embodiment of the invention, the double layer is folded in a spiral fold. Here, too, an outer cover layer preferably comprises the stack of cover films in a U-shape. Combinations of accordion folding and spiral folding are also conceivable.

[0100] By folding the cover film, which can easily have a width of 50 cm, 1 m, 1.5 m, 2 m, 2.5 m or more and is therefore difficult to handle, it is folded to a significantly smaller width. The width is then only 20 cm, 40 cm, 60 cm, with all intermediate dimensions also shown.

[0101] The cover film is preferably made of PE, PP, PA, PBT, or PET film, but can also be paper or a metal foil (for example, aluminum foil). Furthermore, composite films made of the above-mentioned materials are particularly advantageous. However, other materials are also conceivable.

[0102] The adhesive tape and stack of protective films are preferably supplied as roll goods in the form of an Archimedean spiral, usually wound around a cardboard tube, and further preferably attached to pins in an applicator so that they can be rotated.

[0103] This variant of the invention is described with reference to an exemplary embodiment in two figures. These show: Fig. 1 Perspective view of a stack of protective film equipped with adhesive tape in a folded and rolled-up state, Fig. 2 Sectional view along line II in Fig. 1, Fig. 3 Sectional view of another embodiment of a stack of cover films equipped with the adhesive tape.

[0104] Fig.Figure 1 shows a stack of masking film 6 equipped with adhesive tape 2, hereinafter collectively referred to as masking tape 1. The adhesive tape 2 extends in a longitudinal direction L. A tape, i.e., masking tape 1 or adhesive tape 2, is understood to be a tape extending essentially very long, in principle endlessly, in the longitudinal direction L, whose length L is many times greater than its extent along a width B. The masking film 6 extends from the longitudinal side of the adhesive tape 2. The width B of the masking tape 1 in the section of the masking film 6 is typically 500 mm to 2,500 mm.

[0105] The extent along width B is many times greater than the extent along thickness D. "Many times" here means 100 times to over 10,000 times greater.

[0106] The adhesive tape 2 usually comprises a carrier layer 3 and an adhesive layer 4. The carrier layer 3 consists of a film layer.

[0107] The adhesive layer 4 is preferably applied over the entire surface of one side of the carrier layer 3. However, it can also be arranged along a strip on the carrier layer next to the cover film.

[0108] The adhesive tape 2 has a release liner edge section 7, which can also be part of the adhesive layer 4. A release liner edge 8 of the release liner 6 is fixed to the release liner edge section 7.

[0109] The masking tape 1 in Fig.The tape 1 is very long, although only a short section L of the tape is shown here. Advantageously, the tape 1 can be wound into a roll. The tape is preferably transported and stored in this wound state before use. The adhesive layer 4 of the tape 2 is located on the inside of the roll, and the backing layer 3 of the tape 2 is located on the outside. The tape 1 can be wound around a core through which the end of a handle is inserted for application, allowing the tape 1 to be unwound continuously from the roll. The core can be made, for example, of cardboard – even siliconized cardboard – or a plastic such as polyethylene (PE).

[0110] The cover sheet 1 is folded into a stack of sheets 9. The fold lines all run parallel to the longitudinal direction L.

[0111] The Fig.The folded masking tape 1, as depicted in Figure 1, is characterized by an exposed and therefore easily accessible gripping edge 11, which is located opposite the edge of the release film 8, which is laminated onto the edge section 7 of the adhesive tape 2, on the unfolded release film 6. "Easily accessible" here means that the gripping edge 11 extends freely along the entire longitudinal dimension of the masking tape 1 and is located approximately 0 to 10 cm beside and parallel to the adhesive tape 2, more precisely next to the backing layer 3 of the adhesive tape 2. After unwinding the masking tape 1, according to Figure 1, the gripping edge 11 is located approximately 0 to 10 cm away from and parallel to the adhesive tape 2, specifically next to the backing layer 3 of the adhesive tape 2. Fig. 1, the gripping edge 11 is exposed. It is not covered by a covering material or similar, but is visible along its entire longitudinal extent and directly touchable and graspable by the user, and can be explored by semi- or fully machined optics and grasped by semi- or fully machined mechanics when the cover tape 1 is unwound from the roll.

[0112] For particularly easy identification, the handle can be highlighted visually and / or haptically, for example by color, additional folding, gluing and / or by curling.

[0113] Fig. Figure 3 shows a sectional view of another embodiment of the masking tape 1. This further embodiment of the masking tape 1 also has an adhesive tape 2 to which a stack of masking films 9 is adhered along its entire longitudinal extent. In this further embodiment according to Fig. 3 is an inner longitudinal edge of the cover film 6 adhered to an adhesive layer 4 of the adhesive tape. Of course, other fastening methods are also conceivable.

[0114] The stack of cover sheets 9 of the Fig.Figure 3 shows the spirally or snail-shaped stacked two-layer cover film 6. Here, too, an outer cover film layer 12 is wrapped around the cover film stack 9 in an approximately U-shape. The gripping edge 11 of the cover film 6 is folded back. Backwards here means folded away from the adhesive tape 2. This makes the gripping edge 11 particularly easy to grasp. It can be easily grasped, especially with the user's fingers.

[0115] The width B of the unfolded cover film 6 can be between 50 cm and 2.50 m, preferably between 1.4 m and 1.9 m. However, all other intermediate dimensions are also conceivable. The unfolded cover film can also have larger or smaller widths B.

[0116] To produce the masking tape 1, the masking film 6 is first fixed to the edge section 7 of the adhesive tape 2 along its entire longitudinal extent with the masking film edge 8 and then folded in two layers. The masking film is folded over with a slight offset along a fold line running in the longitudinal direction L, and the leading edge 11 is folded towards the adhesive tape 2, so that the leading edge 11 is located on the side of the masking film 6 opposite the adhesive layer 4.

[0117] The cover film 6 is then laid in a double layer over essentially its entire extent. It is subsequently folded accordion-style on the side opposite the handle edge 11 towards the film stack 9, forming a double layer. The accordion fold is made from the outside in, i.e., towards the handle edge 11. This creates an outer folded layer 12 of the cover film 6, which surrounds the other folded layers in a U-shape, preferably completely on three sides, on a side of the film stack 9 facing away from the adhesive tape 2.

[0118] Another method for manufacturing the masking tape begins with folding the film into a double layer. The use of an asymmetrically folded film, already wound onto a core, has proven particularly advantageous. This type of film is obtained, for example, from blown film extrusion, where, in double-sided production, the resulting film tube is cut asymmetrically and then wound up after being folded.

[0119] Another method involves a symmetrical cut, resulting in a tube with a slit at the edge. This tube is then precisely folded on top of each other, and a subsequent edge trim creates asymmetrical film sections. The asymmetrically folded film is then folded according to the previously described procedure, producing the finished film stack. Adhesive tape is then applied to the film stack. In principle, the adhesive tape can be applied to the edge of the release film at any point during production.

[0120] The stack of film can also be pre-folded and wound onto a core. The adhesive tape is then locally fixed to the edge of the release film using a tool that can hold and guide both the tape and the wound stack of film, so that the release tape can be produced with the tool.

[0121] Fig.Figure 1 does not show that the masking tape 1 is wound up. Usually, the masking tape 1 is wound around a Fig. 1 winding axis arranged below the cover tape 1, so that the adhesive layer 4 is arranged on the inside of the winding and the carrier layer 3 of the adhesive tape 1 is arranged on the outside of the winding.

[0122] Advantages of accordion folding according to Fig. One advantage of the cover film 6 is that the cover film 6 of the masking tape 1, which is adhered to the (not shown) work surface, can be completely unfolded by grasping the gripping edge 11 and pulling. Another advantage is that the adhered but not yet unfolded cover film 6 remains in its position, since the outer folded layer 12 completely encloses the stack of cover films 9. This prevents it from unfolding on its own.

[0123] Furthermore, the folds of the foil stack do not have to be at the same height, but can be offset from each other. Examples Sketch of the examples

[0124] Adhesive tapes with the pressure-sensitive adhesive compound are described below in a preferred embodiment using examples, without intending to subject the invention to any limitations.

[0125] Furthermore, comparative examples are listed, illustrating unsuitable adhesive tapes. formulation V1 V2 V3 V4 V5 V6 V7 E1 E2 E3 Base polymer(s) NR Si 80 PIB2 20 PIB3 27 PIB1 30 PIB3 30 PIB1 50 PIB3 28 PIB1 25 PIB3 13 PIB1 37 PIB3 30 PIB1 50 PIB3 35 PIB1 50 PIB3 30 PIB1 40 PIB3 Resin(s) - - - 25 H1 18 H4 20 H1 13 H1 34 H4 11 H3 39 H4 20 H3 15 H3 30 H4 Adhesive strength of steel (N / cm) 3,8 3,5 1,5 15 6,1 21 (KB) 5,0 7,1 5,3 7,3 Tack OK OK OK OK OK OK OK OK OK OK Strip test yellowing Paint defects OK Residues Ghosting Ghosting OK OK OK OK Total (OK / not OK) OK OK nOK (adhesive strength too low, tack) OK OK nOK (too high KK + KB) nOK (too low a track) OK OK OK Legend / Abbreviations KK = Adhesive strength KB = Cohesive fracture Raw materials used - NR: Commercially available natural rubber-based adhesive, such as that used on the product tesa® 51109 - SI: Commercially available silicone-based adhesive, such as that used in the product tesa® 61124 - PIB1: BASF Oppanol B10 SFN, polyisobutylene with weight average molecular weight M w of 36,000 g / mol - PIB2: BASF Oppanol N50 SF, polyisobutylene with weight average molecular weight M w of 340,000 g / mol - PIB3: BASF Oppanol B150, polyisobutylene with weight average molecular weight M w of 2,500,000 g / mol - H1: Yasuhara YS Polyester U115, hydrogenated resin based on terpenephenol - H3: Regalite R1125, resin based on fully hydrogenated hydrocarbon - H4: Regalite R1090, resin based on fully hydrogenated hydrocarbon

[0126] The table on the previous page describes formulations tested as part of the adhesive development process (comparative examples, V1 - V7).

[0127] There are clear differences between suitable adhesive tapes (“good examples” E1 to E3) and those that are not suitable for corresponding masking applications.

[0128] The following explains why the adhesive tapes from the comparison examples are unsuitable.

[0129] V1 shows yellowing. It is an adhesive tape with a PET backing and natural rubber adhesive containing a terpene phenol resin. The yellowing is likely due to components of the adhesive (e.g., accompanying substances in the natural rubber).

[0130] V2 contains a silicone adhesive that can cause yellowing and lead to paint defects and "craters".

[0131] V3 exhibits insufficient adhesive strength, particularly due to strong cohesion combined with low adhesion resulting from the high molecular weight synthetic rubber backbone.

[0132] V4 exhibits both excessively strong adhesive forces and visible adhesive residue after demasking. Furthermore, the proportion of low-molecular-weight PIB is relatively high, resulting in reduced cohesion.

[0133] V5 shows “ghosting”, possibly caused by or at least promoted by the contained terpene phenol resin H1.

[0134] V6 is unsuitable as an adhesive for masking tape because the formulation contains too little high-molecular-weight PIB, resulting in a risk of cohesive failure. Furthermore, the resin content is too high, leading to excessive adhesive strength.

[0135] V7 has insufficient tack, resulting in insufficient initial adhesion of the adhesive, due to the low proportion of low molecular weight PIB.

[0136] The examples are suitable because they meet all the requirements for masking applications.

[0137] The table shows only basic formulations. Therefore, it should be noted that the commercial formulation may also contain antioxidants and fillers.

[0138] The masking tape is specifically designed for automotive bodies and components such as bumpers, motorcycle tanks, etc., during the painting process. It creates sharp paint edges and is suitable for use on flat and highly curved surfaces, as well as for bonding around very tight curves. The masking tape is characterized by the fact that it leaves no residue, ghosting, or yellowing on masked, critical paint surfaces, even after high thermal stress. Assessment criteria; Conducting the tests

[0139] Unless explicitly stated otherwise, measurements are carried out under a test climate of 23 ± 1 °C and 50 ± 5 % relative humidity. Molecular weight

[0140] The molecular weight determinations (of the number-mean molecular weights M) n and) the weight-mean molecular weights M wThe measurements are performed using gel permeation chromatography (GPC). THF (tetrahydrofuran) with 0.1 vol% trifluoroacetic acid is used as the eluent. The measurement is performed at 23 °C. PSS-SDV, 10 µm, 10 3 Å, ID 8.0 mm x 50 mm is used. The columns PSS-SDV, 10 µ, 10 are used for separation. 3 as well as 105 and 107, each with an ID of 8.0 mm x 300 mm. The sample concentration is 0.5 g / l, and the flow rate is 0.5 ml per minute. Calibration is performed using the commercially available ReadyCal kit Poly(styrene) high from PSS Polymer Standard Service GmbH, Mainz, Germany. This is converted universally to polymethyl methacrylate (PMMA) using the Mark Houwink parameters K and alpha, so that the data are given in PMMA mass equivalents. Adhesive strength, KK

[0141] To measure adhesive strength (according to AFERA ​​5001, test method A, test speed: 300 mm / min), 19 mm wide test strips are adhered bubble-free to a finely sanded (FEPA grit 240) stainless steel plate and pressed down with a rubber-wrapped 2 kg roller at a speed of 10 m / min. The steel plate and the protruding end of the adhesive tape are then clamped into the ends of a tensile testing machine so that a pull-off angle of 180° is created. The adhesive tape is pulled off the steel plate at a speed of 300 mm / min. The adhesive strength is given in N / cm. Strip test

[0142] In this test, an adhesive strip is applied to a surface (painted metal sheet with clear lacquer) and then subjected to a temperature load, in this case one hour at 170 °C. The test strip is then quickly removed from the surface at two different angles: 90° and 180° (v = approx. 6 m / min).

[0143] This is done both at room temperature after a 10-minute cooling phase ("cold demasking") and at 60 °C ("warm demasking"). After demasking, the test substrate is subjectively examined and evaluated for discoloration ("yellowing"), adhesive residue, edge formation, and "ghosting" by comparing the results.

[0144] White-painted test panels (clear coats BASF iGloss, BASF StarGloss, BASF ProGloss, PPG CeramiClear 7.0, Axalta Supermar, PPG HTC 2.1) are used for yellowing investigations, while ghosting is investigated on black-painted test panels (BASF ProGloss). Tack

[0145] Tack describes the immediate adhesion of an adhesive to a surface (e.g., thumbtip, so-called finger tack) under a very short contact time (approx. 1 s) and very low contact pressure (approx. 1.5 N).

[0146] The tack must not be too low, as this would prevent rapid adhesive strength development (and therefore rapid adhesion to the substrate). The OK / nOK determination is made in comparison to the commercial reference products (V1, V2). List of reference symbols 1 masking tape 2 adhesive tapes 3 Carrier layer 4 adhesive layers 6 Cover film 7 edge section on the cover film side 8 Cover film edge 9 stacks of foil 11 Handle edge 12 outer folded layers B Width Thickness L Longitudinal direction

Claims

[1] Use of an adhesive tape for masking during the painting of automobile bodies and components, wherein the adhesive tape has a web-shaped carrier material and a coating of a pressure-sensitive adhesive applied thereto on at least one side, wherein the pressure-sensitive adhesive comprises a composition of at least one polyisobutylene (A) having a weight-average molecular weight M w from 30,000 to 800,000 g / mol, of at least one polyisobutylene (B) having a weight-average molecular weight M w from 1,000,000 to 5,000,000 g / mol and at least one adhesive resin (C) selected from the group consisting of terpene resins, aliphatic, cycloaliphatic, aromatic and mixed hydrocarbon resins, wherein the composition has a mixing ratio of • (A) 25 to 35 wt.% • (B) 40 to 50 wt.% and • (C) 15 to 30 wt.% and wherein the sum of the proportions of (A), (B) and (C) is 100 wt.%. [2] Use according to claim 1, characterized by , that at least one polyisobutylene (A) has a weight-average molecular weight M w from 35,000 to 200,000 g / mol and / or at least one polyisobutylene (B) has a weight-average molecular weight M w from 1,000,000 to 2,500,000 g / mol. [3] Use according to claim 1 or 2, characterized by , that per 100 parts by weight of the composition of (A), (B) and (C) • up to 5 parts by weight of UV stabilizers, • up to 10 parts by weight of fillers such as TiO2, pigments, plasticizers such as white oil, paraffin oil • up to 2 parts by weight of graduation agent such as talc and / or • up to 35 parts by weight of flame retardant are added. [4] Use of an adhesive tape according to at least one of claims 1 to 3, characterized bythat a film made of PVC, PO or PET is used as the web-shaped carrier material, preferably PET. [5] Use of an adhesive tape according to at least one of the preceding claims, characterized by that the web-shaped carrier material has a thickness of 20 to 100 µm, preferably 30 to 60 µm. [6] Use of an adhesive tape according to at least one of the preceding claims, characterized by that on one side of the web-shaped carrier material a coating of the pressure-sensitive adhesive is applied and on the other side of the carrier material a release varnish, preferably PVSC carbamate, is applied at least partially, preferably over the entire surface. [7] Use of an adhesive tape according to at least one of the preceding claims, characterized bythat a coating of the pressure-sensitive adhesive is applied to one side of the web-shaped carrier material, wherein a cover material is applied, preferably laminated, in an edge region of the coating extending in the longitudinal direction of the web-shaped carrier material, which cover material extends over the longitudinal edge of the web-shaped carrier material.

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