PLASMA EDGE CAPSULING OF ADHESIVE TAPS

Description

[0001] The invention relates to a method for reducing moisture migration into a bond.

[0002] US 2016 / 0028041 A1 discloses an organic electronic element with a sealing layer. The sealing layer completely surrounds the organic electronic element, such as an OLED, which is applied to a substrate surface. To seal the organic electronic element, a liquid coating containing a silicon component is applied to the outer surface; plasma ions are then implanted into the coating. The resulting sealing layer possesses excellent gas barrier properties. Furthermore, it is transparent to visible light. The plasma causes these liquid-applied silicon compounds to react and form a solid film. A disadvantage of this process, however, is that a liquid layer must first be applied, which is then subsequently treated with a plasma in a second process step.The disadvantage is that the layer thickness cannot be precisely controlled and the process is relatively complex.

[0003] DE 10 2007 006251 A1 discloses a method for the edge-side passivation of pressure-sensitive adhesive tapes, wherein a carrier-free adhesive layer, e.g., based on acrylate, is applied to a polyester film, and a passivation layer is applied along the side edge using a plasma stream. A precursor is added to the plasma stream. WO

[0004] 2016 / 131984 A1 discloses a method for reducing the stickiness of a wound mirror by treating a film with a plasma stream to which a precursor, such as HMDSO, is added. The film with the resulting passivation layer is then applied to the wound mirror of an adhesive tape roll.

[0005] It is an object of the present invention to simplify a method mentioned above for reducing the migration of moisture into a bond.

[0006] With regard to the method, the object is achieved by a method for reducing moisture migration into a bond with the features of claim 1. Adhesive tapes are available in a wide variety of embodiments. The adhesive tape is generally provided as a section of a long adhesive tape; the adhesive tape can be provided, for example, as a sheet or as a section of a roll or, advantageously, as a die-cut or as continuous material on rolls (Archimedean spiral). The adhesive tape can be simply continuous, or holes or openings can be provided in the adhesive tape. The adhesive tape can therefore either completely cover the area delimited by its outer circumference or, if it has openings, only cover parts of it or leave them free. The adhesive tape is shaped significantly larger in two dimensions than in a third dimension.The significantly larger dimensions are the length and width, while the third and significantly smaller dimension is the thickness or height of the adhesive tape. However, the first two dimensions can also be the same size and thus have a circular, square, or other surface. Adhesive tapes can be single-layered or multi-layered, and typical thicknesses range from approximately 1 µm to 5 mm.

[0007] In a single-layer structure, the adhesive tape preferably consists of an adhesive layer; in a multi-layer structure, the adhesive tape can also comprise a carrier material arranged in a carrier layer. The carrier material can be provided with an adhesive layer on one side and another, or even with an adhesive layer on only one side. The carrier material includes all flat structures, for example, films or film sections extended in two dimensions, tapes with an extended length and a limited width, tape sections, diecuts (for example in the form of borders or boundaries of an (opto-)electronic arrangement), multi-layer arrangements, or the like. A wide variety of carriers, such as films, fabrics, nonwovens, and papers, can be combined with various plastics for different applications.

[0008] Polymer films, film composites, or films or film composites provided with organic and / or inorganic layers are preferably used as the material for the carrier layer of the adhesive tape. Such films / film composites can consist of all common plastics used in film production. Examples include, but are not limited to: polyethylene, polypropylene—particularly oriented polypropylene (OPP) produced by mono- or biaxial stretching, cyclic olefin copolymers (COC), polyvinyl chloride (PVC), polyester—particularly polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), ethylene-vinyl alcohol (EVOH), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polycarbonate (PC), polyamide (PA), polyethersulfone (PES), or polyimide (PI).

[0009] The carrier layer can also be combined with organic or inorganic coatings or layers. This can be achieved using conventional processes such as painting, printing, vapor deposition, sputtering, co-extrusion, or lamination. Examples, but not limited to, include oxides or nitrides of silicon and aluminum, indium tin oxide (ITO), or sol-gel coatings.

[0010] The adhesive layer can also be any common adhesive layer.

[0011] The term "bonding" generally describes a manufacturing process for the material-to-material bonding of substrates. During bonding, the adhesive adheres to the substrates through physical interaction – occasionally also through chemical interaction – known as adhesion, usually forming a permanent bond. Since bonding allows for a large-area, force-locking connection of the parts to be joined, and its material-friendly properties make it suitable for joining almost all materials, bonding processes are widely used in both home and industrial applications. Other joining methods, such as welding, soldering, and even screwing, are increasingly being replaced by bonding processes.

[0012] A pressure-sensitive adhesive layer is preferably used as the adhesive layer. Pressure-sensitive adhesives are adhesives that allow a permanent bond to the substrate even under relatively light pressure. They exhibit an adhesive strength greater than 1 N / cm and can be removed from the substrate after use, leaving essentially no residue. Pressure-sensitive adhesives are permanently tacky at room temperature, meaning they have a sufficiently low viscosity and high tackiness, allowing them to wet the surface of the respective substrate even under light pressure. The bondability of such adhesives is based on their adhesive properties, and their removability on their cohesive properties.

[0013] Pressure-sensitive adhesives comprise a base and a cross-linkable component, also known as reactive resin.

[0014] Various materials, especially non-polar elastomers, can be used as a basis for pressure-sensitive adhesives.

[0015] Nonpolar elastomers, such as vinylaromatic block copolymers, are characterized by their ability to dissolve in nonpolar solvents, i.e., solvents and / or solvent mixtures whose polarity corresponds to ethyl acetate or is less than polar. These are, in particular, solvents and / or solvent mixtures with a dielectric constant of less than 6.1 [http: / / en.wikipedia.org / wiki / Solvent as of October 11, 2017] and / or with Hansen parameters δP Polar ≤ 5.3; δH Hydrogen bonding ≤ 7.2 [Abbott, Steven and Hansen, Charles M. (2008) Hansen Solubility Parameters in Practice, ISBN 0-9551220-2-3 or Hansen, Charles M. (2007) Hansen solubility parameters: a user's handbook CRC Press, ISBN 0-8493-7248-8].

[0016] If block copolymers are used as elastomers, they contain at least one block type with a softening temperature of greater than 40 °C, such as vinyl aromatics (including partially or fully hydrogenated variants), methyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate and isobornyl acrylate.

[0017] Further preferably, the block copolymer contains a block type with a softening temperature of less than - 20 °C.

[0018] Examples of polymer blocks with low softening temperatures ("soft blocks") are polyethers such as polyethylene glycol, polypropylene glycol or polytetrahydrofuran, polydienes such as polybutadiene or polyisoprene, (partially) hydrogenated polydienes such as polyethylene butylene, polyethylene propylene or polybutylene butadiene, polybutylene, polyisobutylene, polyalkyl vinyl ethers, polymer blocks of α,β-unsaturated esters such as acrylate copolymers in particular.

[0019] The soft block is designed to be non-polar and preferably contains butylene or isobutylene or hydrogenated polydienes as a homopolymer block or copolymer block, the latter preferably copolymerized with themselves or with each other or with other, particularly preferably non-polar comonomers. Suitable non-polar comonomers include, for example, (partially) hydrogenated polybutadiene, (partially) hydrogenated polyisoprene, and / or polyolefins.

[0020] The crosslinkable component, also referred to as reactive resin, consists of a cyclic ether and is suitable for radiation-chemical and, if necessary, thermal crosslinking with a softening temperature of less than 40 °C, preferably less than 20 °C.

[0021] Reactive resins based on cyclic ethers are primarily epoxides, i.e., compounds containing at least one oxirane group, or oxetanes. They can be aromatic or, in particular, aliphatic or cycloaliphatic in nature.

[0022] Usable reactive resins can be monofunctional, difunctional, trifunctional, tetrafunctional or higher functional up to polyfunctional, where the functionality refers to the cyclic ether group.

[0023] Examples, without wishing to be limited, are 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate (EEC) and derivatives, dicyclopendadiene dioxide and derivatives, 3-ethyl-3-oxetanemethanol and derivatives, tetrahydrophthalic acid diglycidyl ester and derivatives, hexahydrophthalic acid diglycidyl ester and derivatives, 1,2-ethanediglycidyl ether and derivatives, 1,3-propanediglycidyl ether and derivatives, 1,4-butanediol diglycidyl ether and derivatives, higher 1,n-alkanediglycidyl ethers and derivatives, bis-[(3,4-epoxycyclohexyl)methyl]-adipate and derivatives, vinylcyclohexyl dioxide and derivatives, 1,4-cyclohexanedimethanol bis-(3,4-epoxycyclohexanecarboxylate) and Derivatives, 4,5-epoxytetrahydrophthalic acid diglycidyl ester and derivatives, bis-[1-ethyl(3-oxetanyl)methyl] ether and derivatives, pentaerythritol tetraglycidyl ether and derivatives, bisphenol A diglycidyl ether (DGEBA), hydrogenated bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, epoxyphenol novolaks, hydrogenated epoxyphenol novolaks,Epoxycresol novolaks, hydrogenated epoxycresol novolaks, 2-(7-oxabicyclo)spiro[1,3-dioxane-5,3'-[7]oxabicyclo[4.1.0]-heptane], 1,4-bis((2,3-epoxypropoxy)methyl)cyclohexane.,

[0024] Reactive resins can be used in their monomeric or dimeric, trimeric, etc., up to their oligomeric form.

[0025] Mixtures of reactive resins with each other but also with other coreactive compounds such as alcohols (monofunctional or polyfunctional) or vinyl ethers (monofunctional or polyfunctional) are also possible.

[0026] Particularly preferably, the adhesive tape is a roll of adhesive tape which is made from the ACX plus< -range from the tesa company.

[0027] Such adhesive tapes preferably comprise a carrier layer, also referred to as the hard phase. The polymer base of the hard phase is preferably selected from the group consisting of polyvinyl chlorides (PVC), polyethylene terephthalates (PET), polyurethanes, polyolefins, polybutylene terephthalates (PBT), polycarbonates, polymethyl methacrylates (PMMA), polyvinyl butyrals (PVB), ionomers, and mixtures of two or more of the above-listed polymers. The polymer base of the hard phase is particularly preferably selected from the group consisting of polyvinyl chlorides, polyethylene terephthalates, polyurethanes, polyolefins, and mixtures of two or more of the above-listed polymers. The hard phase is essentially a polymer film whose polymer base is selected from the above materials.A "polymer film" is understood to be a thin, flat, flexible, windable web whose material basis is essentially formed by one or more polymer(s).

[0028] "Polyurethanes" are broadly understood to mean polymeric substances in which repeating units are linked together by urethane groups -NH-CO-O-.

[0029] "Polyolefins" are polymers that contain at least 50% repeat units of the general structure -[-CH2-CR1R2-]n-, where R1 represents a hydrogen atom and R2 represents a hydrogen atom or a linear or branched, saturated aliphatic or cycloaliphatic group. Where the polymer base of the hard phase comprises polyolefins, these are particularly preferably polyethylenes, in particular ultra-high molecular weight polyethylenes (UHMWPE).

[0030] The "polymer base" is understood to mean the polymer or polymers that constitute(s) the largest proportion by weight of all polymers contained in the layer or phase in question.

[0031] The thickness of the hard phase is in particular ≤ 150 µm. The thickness of the hard phase is preferably 10 to 150 µm, particularly preferably 30 to 120 µm, and in particular 50 to 100 µm, for example 70 to 85 µm. "Thickness" refers to the extent of the respective layer or phase along the z-ordinate of an imaginary coordinate system, in which the plane spanned by the machine direction and the direction transverse to the machine direction forms the xy-plane. The thickness is determined by measuring at least five different locations on the respective layer or phase and subsequently calculating the arithmetic mean of the measurement results. The thickness measurement of the hard phase is carried out in accordance with DIN EN ISO 4593.

[0032] Such adhesive tapes may further comprise an adhesive layer or soft phase comprising a polymer foam, a viscoelastic mass, and / or an elastomeric mass. The polymer base of the soft phase is preferably selected from polyolefins, polyacrylates, polyurethanes, and mixtures of two or more of the above-listed polymers.

[0033] In the simplest version, the adhesive tape consists only of a soft phase.

[0034] A "polymer foam" is understood to be a structure of gas-filled spherical or polyhedral cells bounded by liquid, semi-liquid, highly viscous, or solid cell walls; furthermore, the main component of the cell walls is a polymer or a mixture of several polymers.

[0035] A "viscoelastic mass" is defined as a material that, in addition to pure elasticity (returning to its original state after external mechanical action), also exhibits characteristics of a viscous fluid, such as the occurrence of internal friction upon deformation. Polymer-based pressure-sensitive adhesives, in particular, are considered viscoelastic masses.

[0036] An "elastomeric mass" is understood to be a material that exhibits rubber-elastic behavior and can be repeatedly stretched to at least twice its length at 20 °C and immediately returns to approximately its original dimension after the constraint required for the stretching is removed.

[0037] Regarding the understanding of the terms "polymer base," "polyurethanes," and "polyolefins," the above applies. "Polyacrylates" are polymers whose molar monomer base consists of at least 50% acrylic acid, methacrylic acid, acrylic esters, and / or methacrylic esters, with acrylic esters and / or methacrylic esters generally being present at least in part, and preferably at least 50%. In particular, a "polyacrylate" is understood to mean a polymer obtainable by radical polymerization of acrylic and / or methylacrylic monomers and, optionally, other copolymerizable monomers.

[0038] The polymer base of the soft phase is particularly preferably selected from polyolefins, polyacrylates, and mixtures of two or more of the above-listed polymers. If polyolefins are part of the polymer base of the soft phase, they are preferably selected from polyethylenes, ethylene-vinyl acetate copolymers (EVA), and mixtures of polyethylenes and ethylene-vinyl acetate copolymers (PE / EVA blends). The polyethylenes can be various types of polyethylene, for example HDPE, LDPE, LLDPE, blends of these polyethylene types, and / or mixtures thereof.

[0039] In one embodiment, the soft phase comprises a foam and a pressure-sensitive adhesive layer arranged above and below the foamed layer, wherein the polymer base of the foam consists of one or more polyolefins and the polymer base of the pressure-sensitive adhesive layers consists of one or more polyacrylates. Particularly preferably, the polymer base of the foam consists of one or more polyethylenes, ethylene-vinyl acetate copolymers, and mixtures of one or more polyethylenes and / or ethylene-vinyl acetate copolymers. Most preferably, the polymer base of the foam consists of one or more polyethylenes.

[0040] The polyolefin-based foam itself is either non-adhesive or very slightly adhesive. The bond with the hard phase or the substrate is therefore advantageously achieved through the pressure-sensitive adhesive layers. The foaming of the polyolefin-based foam starting material is preferably induced by added propellant gas in the sense of physical foaming and / or by a chemical foaming agent, for example, azodicarboxylic acid diamine.

[0041] In another embodiment, the soft phase is a pressure-sensitive adhesive polymer foam whose polymer base consists of one or more polyacrylates. "Pressure-sensitive adhesive foam" means that the foam itself is a pressure-sensitive adhesive, thus eliminating the need to apply an additional pressure-sensitive adhesive layer. This is advantageous because fewer layers need to be joined during the manufacturing process, reducing the risk of delamination and other undesirable phenomena at the layer boundaries.

[0042] A "pressure-sensitive adhesive" is a material whose cured film remains permanently tacky and adhesive at room temperature in a dry state, whereby bonding occurs immediately on a variety of different substrates by light contact pressure.

[0043] The polyacrylates are preferably obtainable by at least partial polymerization of functional monomers crosslinkable with epoxy groups. These 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 particularly advantageous if the polyacrylates contain polymerized acrylic acid and / or methacrylic acid. All of these groups are crosslinkable with epoxy groups, which advantageously makes the polyacrylates amenable to thermal crosslinking with incorporated epoxides.

[0044] Other monomers that can be used as comonomers for the polyacrylates, in addition to acrylic acid and / or methacrylic acid esters with up to 30 C atoms, include 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 1 or 2 double bonds or mixtures of these monomers.

[0045] The properties of the polyacrylate 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 polyacrylates can preferably be traced back to the following monomer composition: (a) acrylic acid esters and / or methacrylic acid esters of the following formula CH 2 = C(R')(COOR") where RI< = H or CH 3 and R II< is an alkyl radical having 4 to 14 C atoms, (b) olefinically unsaturated monomers having functional groups of the type already defined for reactivity with epoxy groups, (c) optionally further acrylates and / or methacrylates and / or olefinically unsaturated monomers which are copolymerizable with component (a).

[0046] The polyacrylates are preferably based on a monomer composition containing 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.). In this case, the polymerization product has a glass transition temperature ≤ 15 °C (DMA at low frequencies) and pressure-sensitive adhesive properties.

[0047] 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, isobutyl acrylate, isooctyl acrylate, isooctyl methacrylate, and their branched isomers, such as, for example, 2-ethylhexyl acrylate or 2-ethylhexyl methacrylate.

[0048] 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.

[0049] For component (b) monomers with functional groups selected from the group comprising: hydroxyl, carboxy, sulfonic acid or phosphonic acid groups, acid anhydrides, epoxides, amines are preferably used.

[0050] 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, itasconic acid, maleic anhydride, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 6-hydroxyhexyl methacrylate, allyl alcohol, glycidyl acrylate, glycidyl methacrylate.

[0051] In principle, any vinyl-functionalized compound that is 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.

[0052] Beispielhafte Monomere der Komponente (c) sind: Methylacrylat, Ethylacrylat, Propylacrylat, Methylmethacrylat, Ethylmethacrylat, Benzylacrylat, Benzylmethacrylat, sec-Butylacrylat, tert-Butylacrylat, Phenylacrylat, Phenylmethacrylat, Isobornylacrylat, Isobornylmethacrylat, tert-Butylphenylacrylat, tert-Butylaphenylmethacrylat, Dodecylmethacrylat, Isodecylacrylat, Laurylacrylat, n-Undecylacrylat, Stearylacrylat, Tridecylacrylat, Behenylacrylat, Cyclohexylmethacrylat, Cyclopentylmethacrylat, Phenoxyethylacrlylat, Phenoxyethylmethacrylat, 2-Butoxyethyl-methacrylat, 2-Butoxyethylacrylat, 3,3,5-Trimethylcyclohexylacrylat, 3,5-Dimethyl-adamantylacrylat, 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, Ethoxytriethylen-glykolmethacrylat, Octafluoropentylacrylat, Octafluoropentylmethacrylat, 2,2,2-Trifluoro-ethylmethacrylat, 1,1,1,3,3,3-Hexafluoroisopropylacrylat, 1,1,1,3,3,3-Hexafluoro-isopropylmethacrylat, 2,2,3,3,3-Pentafluoropropylmethacrylat, 2,2,3,4,4,4-Hexafluoro-butylmethacrylat, 2,2,3,3,4,4,4-Heptafluorobutylacrylat, 2,2,3,3,4,4,4-Heptafluoro-butylmethacrylat, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluorooctylmethacrylat, Dimethyl-aminopropylacrylamid, Dimethylaminopropylmethacrylamid, N-(1-Methylundecyl)acrylamid, N-(n-Butoxymethyl)acrylamid, N-(Butoxymethyl)methacrylamid, N-(Ethoxymethyl)acrylamid,N-(n-octadecyl)acrylamide, further N,N-dialkyl-substituted amides, 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-vinyl lactam, N-vinylpyrrolidone, styrene, a- and p-methylstyrene, a-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, 3,4-Dimethoxystyrene. Macromonomers such as 2-polystyrene ethyl methacrylate (molecular weight M w from 4000 to 13000 g / mol), poly(methyl methacrylate) ethyl methacrylate (M w from 2000 to 8000 g / mol).

[0053] 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.

[0054] 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.

[0055] 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 0.01 to 5, in particular 0.1 to 2 wt.% (based on the total weight of the monomers).

[0056] 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, cyclohexylsulfonyl acetyl peroxide, diisopropyl percarbonate, t-butyl peroctoate, and benzpinacol. A highly preferred procedure 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.

[0057] Suitable solvents for the preparation of the polyacrylates are alcohols such as methanol, ethanol, N- and isopropanol, N- and isobutanol, 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.

[0058] Preferably, after the production (polymerization) of the polyacrylates, a concentration step is carried out, 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).

[0059] After the concentration step, the polymers can be transferred to a compounder. If necessary, the concentration and compounding can also take place in the same reactor.

[0060] 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 of 100,000 to 1,000,000 g / mol, extremely preferably in a range of 150,000 to 500,000 g / mol (the data for the average molecular weight M w and the polydispersity PD in this document refer to the determination by gel permeation chromatography. THF with 0.1 vol.% trifluoroacetic acid was used as eluent. The measurement was carried out at 25 °C. PSS-SDV, 5 µm, 10 3< Å, ID 8.0 mm × 50 mm was used as pre-column. For separation, the columns PSS-SDV, 5 µm, 10 3< Å, 10 5< Å and 10 6< Å, each with ID 8.0 mm × 300 mm, were used. The sample concentration was 4 g / l, the Flow rate 1.0 ml per minute. Measurements were made against PMMA standards (µ = µm; 1 Å = 10 -10 < m).For this purpose, it may be advantageous to carry out the polymerization in the presence of suitable polymerization regulators such as thiols, halogen compounds and / or alcohols in order to adjust the desired average molecular weight.

[0061] The polyacrylate preferably has 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.

[0062] Polyacrylates with a narrow molecular weight distribution (polydispersity PD < 4) are particularly suitable. Despite their relatively low molecular weight, these materials have particularly good shear strength after crosslinking. Furthermore, the lower polydispersity enables easier processing from the melt, since 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 advantageously be produced by anionic polymerization or by controlled radical polymerization methods, the latter being particularly suitable. Examples of such polyacrylates produced by the RAFT process are described in US Pat. Nos. 6,765,078 B2 and 6,720,399 B2. Corresponding polyacrylates can also be produced via N-oxyls, as described, for example, in EP 1 311 555 B1.Atom transfer radical polymerization (ATRP) can also be advantageously used for the synthesis of narrowly distributed polyacrylates. Monofunctional or difunctional, secondary or tertiary halides are preferred as initiators, and Cu, Ni, Fe, Pd, Pt, Ru, Os, Rh, Co, Ir, Ag, or Au complexes are used for abstraction of the halide(s). The various ATRP options are described in US Pat. Nos. 5,945,491 A, 5,854,364 A, and 5,789,487 A.

[0063] The monomers used to produce the polyacrylates 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.

[0064] The polyacrylate(s) are preferably crosslinked by linking reactions—particularly in the sense of addition or substitution reactions—of the functional groups contained therein with thermal crosslinkers. Any thermal crosslinker may be used that both ensures a sufficiently long processing time to prevent gelling during processing and leads to rapid post-crosslinking of the polymer to the desired degree of crosslinking at temperatures lower than the processing temperature, particularly at room temperature. For example, a combination of polymers containing carboxyl, amine, and / or hydroxyl groups and isocyanates as crosslinkers is possible, in particular the aliphatic or amine-deactivated trimerized isocyanates described in EP 1 791 922 A1.

[0065] 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 types 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).

[0066] 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.

[0067] The thermal crosslinker used is preferably, for example, trimerized isocyanate, in an amount of 0.1 to 5% by weight, in particular 0.2 to 1% by weight, based on the total amount of the polymer to be crosslinked.

[0068] The thermal crosslinker preferably comprises at least one substance containing epoxy groups. These substances are, in particular, multifunctional epoxides, i.e., those with at least two epoxy groups; accordingly, the building blocks bearing the functional groups are indirectly linked. The epoxy-containing substances can be both aromatic and aliphatic compounds.

[0069] 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).

[0070] 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.

[0071] Particularly preferred 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.

[0072] Amines (formally to be understood as substitution products of ammonia; in the following formulas, 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.

[0073] In principle, primary (NRH 2 ), secondary (NR 2 H), and tertiary amines (NR 3 ) can be selected as accelerators, including, of course, 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 advantageously used as accelerators. Diethylenetriamine, triethylenetetramine, and trimethylhexamethylenediamine, for example, are particularly suitable.

[0074] 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 include 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 be used.

[0075] 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.

[0076] Furthermore, it can be provided that an inherently pressure-sensitive polymer foam with a polymer base consisting of polyacrylate(s) is coated on the top and / or bottom with a pressure-sensitive adhesive, wherein the polymer base of this pressure-sensitive adhesive preferably also consists of polyacrylates. Alternatively, other or differently pretreated adhesive layers, for example, pressure-sensitive adhesive layers and / or heat-activatable layers based on polymers other than poly(meth)acrylates, can be laminated to the foamed layer. Suitable base polymers are natural rubbers, synthetic rubbers, acrylate block copolymers, vinylaromatic block copolymers, in particular styrene block copolymers, EVA, polyolefins, polyurethanes, polyvinyl ethers, and silicones.Preferably, these layers do not contain any significant proportions of migratable components that are so compatible with the material of the foamed layer that they diffuse into the foamed layer in significant quantities and change its properties.

[0077] In general, the soft phase of the adhesive tape can contain at least one tackifying resin. Particularly suitable tackifying resins are aliphatic, aromatic, and / or alkylaromatic hydrocarbon resins, hydrocarbon resins based on pure monomers, hydrogenated hydrocarbon resins, functional hydrocarbon resins, and natural resins. The tackifying resin is preferably selected from the group comprising pinene, indene, and rosin resins, their disproportionated, hydrogenated, polymerized, and / or esterified derivatives and salts, terpene resins and terpene-phenolic resins, as well as C5, C9, and other hydrocarbon resins. Combinations of these and other resins can also be advantageously used to adjust the properties of the resulting adhesive as desired. The tackifying resin is particularly preferably selected from the group comprising terpene-phenolic resins and rosin esters.

[0078] The soft phase of the adhesive tape may contain one or more fillers. The filler(s) may be present in one or more layers of the soft phase.

[0079] The soft phase preferably comprises a polymer foam, and the polymer foam contains partially or fully expanded microballoons, particularly when the polymer base of the polymer foam comprises one or more polyacrylates, and very particularly preferably when the polymer base of the polymer foam consists of one or more polyacrylates. Microballoons are elastic hollow spheres that have a thermoplastic polymer shell; they are therefore also referred to as expandable polymer microspheres or hollow microspheres. These spheres are filled with low-boiling liquids or liquefied gas. Polyacrylonitrile, polyvinyl dichloride (PVDC), polyvinyl chloride (PVC), polyamides, or polyacrylates are particularly used as shell materials. Lower alkanes, for example isobutane or isopentane, are particularly suitable as low-boiling liquids, which are enclosed in the polymer shell as liquefied gas under pressure.Through physical action on the microballoons, for example, through the application of heat, particularly through the supply or generation of heat, e.g., caused by ultrasound or microwave radiation, the outer polymer shell softens, while the liquid propellant gas contained within the shell simultaneously transforms into a gaseous state. At a certain pressure-temperature pairing—also known as the critical pairing—the microballoons expand irreversibly and expand three-dimensionally. The expansion is complete when the internal and external pressures equalize. Since the polymer shell is retained, a closed-cell foam is created.

[0080] A variety of microballoon types are commercially available, such as the Expancel DU types (dry unexpanded) from Akzo Nobel, which differ essentially in their size (6 to 45 µm diameter in the unexpanded state) and the starting temperature required for expansion (75 °C to 220 °C).

[0081] Furthermore, unexpanded microballoon types are also available as an aqueous dispersion with a solids or microballoon content of approximately 40 to 45 wt.%, as well as polymer-bound microballoons (masterbatches), for example, in ethyl vinyl acetate with a microballoon concentration of approximately 65 wt.%. So-called microballoon slurry systems are also available, in which the microballoons are present as an aqueous dispersion with a solids content of 60 to 80 wt.%. Like the DU types, both the microballoon dispersions, the microballoon slurries, and the masterbatches are suitable for foaming a polymer foam contained in the soft phase of the adhesive tape.

[0082] The polymer foam particularly preferably contains microballoons which, in the unexpanded state at 25 °C, have a diameter of 3 µm to 40 µm, in particular 5 µm to 20 µm, and / or after expansion a diameter of 10 µm to 200 µm, in particular 15 µm to 90 µm.

[0083] The polymer foam preferably contains up to 30 wt.% microballoons, in particular between 0.5 wt.% and 10 wt.%, in each case based on the total mass of the polymer foam.

[0084] The polymer foam of the soft phase of the adhesive tape, if it comprises a polymer foam, is preferably characterized by the substantial absence of open-cell cavities. Particularly preferably, the polymer foam has a proportion of cavities without their own polymer shell, i.e., open-cell cavities, of no more than 2 vol%, in particular no more than 0.5 vol%. The polymer foam is thus preferably a closed-cell foam.

[0085] Optionally, the soft phase of the adhesive tape may also contain powdered and / or granular fillers, dyes and pigments, in particular abrasive and reinforcing fillers, such as chalks (CaCO3), titanium dioxide, zinc oxides and carbon black, even in high proportions, i.e. from 0.1 to 50 wt.% based on the total mass of the soft phase.

[0086] Furthermore, flame-retardant fillers such as ammonium polyphosphate; electrically conductive fillers such as conductive carbon black, carbon fibers and / or silver-coated spheres; thermally conductive materials such as boron nitride, aluminum oxide, silicon carbide; ferromagnetic additives such as iron(III) oxides; other additives to increase volume such as blowing agents, solid glass spheres, hollow glass spheres, carbonized microspheres, phenolic hollow microspheres, microspheres made of other materials; silicic acid, silicates, organically renewable raw materials such as wood flour, organic and / or inorganic nanoparticles, fibers; ageing inhibitors, light stabilizers, ozone protectants and / or compounding agents can be included in the soft phase. Preferably, primary ageing inhibitors, e.g. 4-methoxyphenol or Irganox®< 1076, as well as secondary ageing inhibitors, e.g.Irgafos ®< TNPP or Irgafos ®< 168 from BASF can be used, optionally in combination with each other. Phenothiazine (C radical scavenger) and hydroquinone methyl ether in the presence of oxygen, as well as oxygen itself, can be used as additional anti-aging agents.

[0087] The thickness of the soft phase is preferably 200 to 1800 µm, particularly preferably 300 to 1500 µm, especially 400 to 1000 µm. The thickness of the soft phase is determined according to ISO 1923.

[0088] The bonding of the hard and soft phases, or of the layers provided within the hard and / or soft phases, to form an adhesive tape can be achieved, for example, by lamination, coating, or coextrusion. It is possible for the hard and soft phases to be bonded directly to each other. It is also possible for one or more adhesion-promoting layers to be arranged between the hard and soft phases. The adhesive tape may also contain additional layers.

[0089] Preferably, at least one of the layers to be joined together is pretreated, more preferably several of the layers to be joined together are pretreated, and most preferably all of the layers to be joined together are pretreated with corona (with air or nitrogen), plasma (air, nitrogen or other reactive gases or reactive compounds that can be used as aerosol) or flame pretreatment methods.

[0090] On the reverse side, i.e., on the side of the hard phase facing away from the substrate, a functional layer is preferably applied, which, for example, has release properties or UV-stabilizing properties. This functional layer preferably consists of a film with a thickness of ≤ 20 µm, more preferably ≤ 10 µm, in particular ≤ 8 µm, for example ≤ 5 µm, or a varnish with a thickness of ≤ 10 µm, more preferably ≤ 6 µm, in particular ≤ 3 µm, for example ≤ 1.5 µm. Both the film and the varnish preferably contain a UV absorber, and / or the polymer base of the film or varnish contains UV-absorbing and / or UV-repellent groups.

[0091] Films can be applied to the back of the hard phase by lamination, coating, or coextrusion. The film is preferably a metallized film. The polymer base of the film is preferably selected from the group consisting of polyarylenes, polyvinyl chlorides (PVC), polyethylene terephthalates (PET), polyurethanes, polyolefins, polyethylene terephthalates (PBT), polycarbonates, polymethyl methacrylates (PMMA), polyvinyl butyrals (PVB), ionomers, and mixtures of two or more of the above-listed polymers. "Main component" here means "component with the largest weight fraction based on the total weight of the film." With the exception of polyarylenes, all listed film materials preferably have a high content of UV stabilizers.

[0092] In a specific embodiment, the adhesive tape consists, in order directed toward the substrate, of a functional layer (as described above), a hard phase, and a soft phase consisting of a pressure-sensitive adhesive layer, a polymer foam whose polymer base consists of one or more polyolefins, and another pressure-sensitive adhesive layer. The lower pressure-sensitive adhesive layer can be covered with a release liner, but this is not considered part of the adhesive tape.

[0093] In another specific embodiment, the adhesive tape consists, in a sequence directed toward the substrate, of a functional layer (as described above), a hard phase, and a pressure-sensitive soft phase whose polymer base consists of one or more polyacrylates. In this embodiment, too, the underside of the soft phase, i.e., the side facing the substrate, can be covered with a release liner, but this is not considered part of the adhesive tape.

[0094] The adhesive tapes are preferably foamed acrylate masses, in particular of the type described above, which may additionally have one (or more) intermediate carriers.

[0095] Essential to the invention of the method is that a hydrophobic passivation layer is applied by means of a plasma stream, particularly to the outer side edges of the adhesive tape during its production or after the adhesive tape has been applied to a substrate surface. An atmospheric pressure plasma process is preferably used.

[0096] The risk of moisture migrating behind a bond is prevented by applying a hydrophobic passivation layer to the outside edge of the adhesive layer using a plasma stream. Typically, after the adhesive tape is applied between two substrate surfaces being bonded together, only the outer edge surrounding the adhesive tape is exposed and exposed to the risk of moisture migrating behind the adhesive layer due to water and humidity.

[0097] The free side edge is coated with a hydrophobic passivation layer. According to the invention, a plasma process is used for this purpose. The treatment of the side edge of the adhesive layer takes place at or near atmospheric pressure.

[0098] To carry out the plasma process, a setup with a plasma nozzle is used, to which a process gas to be ionized, preferably in the form of ambient air, is fed. Furthermore, a precursor is fed to the outlet of the plasma nozzle. The precursor is a silane or siloxane that is vaporized and introduced into the plasma stream using a carrier gas, such as nitrogen or a noble gas. The precursor is aminopropyltriethoxysilane, perfluorooctyltriethoxysilane, or hexamethyldisiloxane. A pure silicon oxide layer is not to be expected during polymerization, i.e., the application of the plasma stream to the substrate surface. The proportion of carbon due to unreacted hydrocarbon chains from the precursor molecule, i.e., the hexamethyl chains in the case of hexamethyldisiloxane, can be up to 12% by weight of the coating.This additional weight fraction in the silicon oxide layer creates a hydrophobic effect. The non-hydrophilic layer allows water droplets to bead up and release water from the adhesive tape sides and the bonding interface. This removes the liquid medium, i.e., the condensed water, from the bonding zone, and water migration into the bond is prevented due to the water's polarity.

[0099] The adhesive tape usable in the process according to the invention comprises an adhesive layer with a longitudinal extension and at least one lateral edge running along the longitudinal extension. A hydrophobic passivation layer is applied along the lateral edge of the adhesive layer. The hydrophobic passivation layer is applied according to one of the above-mentioned methods.

[0100] In a preferred embodiment of the adhesive tape, the hydrophobic passivation layer is formed as a SiOx layer with a weight fraction of up to 12% carbon.

[0101] The hydrophobic passivation layer is preferably produced in an atmospheric pressure plasma process with one of the above-mentioned precursors, in particular HMDSO, using ambient air as process gas.

[0102] Advantageously, the adhesive layer has at least two, preferably exactly two, side edges provided with the hydrophobic passivation layer. The adhesive layer is preferably a layer of an adhesive tape wound onto a roll.

[0103] The adhesive layer may comprise at least one elastomer and one reactive resin. Regarding the structure of the elastomer and the reactive resin, reference is made to the above explanations. The adhesive layer may also comprise a pressure-sensitively adhesive soft phase. Reference is also made to the above explanations in this regard.

[0104] The invention is described using an exemplary embodiment in two figures. Showing: Fig. 1 shows a basic structure of a plasma nozzle used, Fig. 2 shows a bar graph for evaluating the effect of plasma edge encapsulation.

[0105] Fig. 1 shows the basic view of a plasma nozzle 1, which is an OpenAir system of the Plasmatreat GmbH.

[0106] A plasma nozzle 1 comprises a precursor unit 2, which is located in the Fig. 1shown on the left, and a plasma unit 3. The precursor unit 2 generates a carrier gas 6 enriched with a precursor 4, while the plasma unit 3 generates a plasma 7. The precursor 4 and the plasma 7 are combined in a nozzle head 8.

[0107] Plasma 7 is understood here to be a high-energy process gas 11, in particular an excited and ionized air-nitrogen mixture. To generate it, the process gas 11 is first fed to the plasma unit 3 through an inlet 9. The process gas 11 here is air or nitrogen or a mixture thereof. The process gas 11 is introduced into the plasma unit 3 through the inlet 9 and passes through a diaphragm 12 with bores into a discharge zone 13, through which the process gas 11 flows. In the discharge zone 13, the process gas 11 is guided past an electrode tip 14, to which a high-frequency alternating voltage of several kilovolts and a frequency of 10 kHz is connected.A strong alternating electric field is created between the electrode tip 14 and a counter electrode, which can be, for example, a grounded stainless steel housing 16. This field leads to a so-called corona discharge, which ionizes the process gas 11 flowing past the electrode tip 14 through the plasma unit 3 and converts it into a stream of plasma 7. The plasma 7 is guided through the nozzle head 8, to which the precursor unit 2 is connected at a lateral inlet 17.

[0108] The side inlet 17 of the nozzle head 8 is connected to the precursor unit 2. The precursor unit 2 comprises a first supply for the precursor 4 and a second supply for the carrier gas 6. Air, nitrogen, or a mixture of air and nitrogen can also be used as the carrier gas 6. The precursor 4 is atomized and added to the carrier gas 6 in droplet form. The mixture enters an evaporator 18, where temperatures above the boiling point of the precursor 4 prevail. An organic polyfunctional silane, for example, hexamethyldisiloxane (HMDSO), can be used as the precursor 4.

[0109] The precursor 4 used here is hexamethyldisiloxane (HMDSO), which is added to the carrier gas 6 at rates ranging from 10, 20, 40 g / h to 150 g / h. The temperature in the evaporator 18 is approximately 120 °C, thus above the boiling point of HMDSO, which is approximately 100 °C.

[0110] A precursor gas 19 escaping from the evaporator 18 is fed to the nozzle head 8 and mixed there with the plasma 7. The precursor 4 thus reaches a side edge of an adhesive layer 20 with the plasma 7.

[0111] The plasma nozzle 1 is at a perpendicular angle to the side edge of the adhesive layer 20 and opens into the nozzle head 8.

[0112] The treatment of the side edge of the adhesive layer 20 takes place at or near atmospheric pressure, although the pressure in the electrical discharge zone 13 of the plasma nozzle 1 may also be higher. In this exemplary embodiment, a plasma 7 is understood to be an atmospheric-pressure plasma, which is an electrically activated homogeneous reactive gas that is not in thermal equilibrium, with a pressure close to ambient pressure in its effective range. Generally, the pressure is 0.5 bar higher than ambient pressure. The electrical discharges or the ionization processes in the electric field of the discharge zone 13 activate the process gas 11, and highly excited states are generated in the gas components.The precursor 4 is then supplied in gaseous form or as an aerosol to the process gas 11 in the nozzle head 8 via a gas-conducting channel via the lateral inlet 17, which precursor forms the actual silicon oxide layer on the surface of the side edge of the adhesive layer.

[0113] Ambient air is used as process gas 11.

[0114] In one embodiment, the following structure with the following conditions and parameters was used for the side edge encapsulation: Plasma nozzle: Generator FG 5001, fixed nozzle 216028WE (Plasmatreat) Precursor: Hexamethyldisiloxane (HMDSO), precursor quantity: 10 - 150 g / hour Treatment speed: 40 m / min Nozzle distance: 15 mm PCT (Pulse Cycle Time): 20% and 100% Evaporator temperature: 120 °C

[0115] In principle, nanocoated side edges reduce the absorption of water into the adhesive, particularly the carrier components of ACX plus< . This is particularly achieved with parameter settings that primarily produce a glassy deposit with low organic content. An example is ACX plus< 6812, which shows significant improvements under stress conditions such as damp heat 85 / 85 and 40 °C at 100% relative humidity. Precursors that can impart pronounced hydrophobicity are also interesting. Adhesive joints are normally permanently wetted with a layer of water under test conditions because the ingredients of the adhesive products contain sufficient polar groups. This promotes the migration of water molecules into the bulk of the adhesive product and the migration of moisture into the boundary layer.Hydrophobic properties of an adhesive joint cause water to "drain" away as droplets and prevent the formation of a continuous water film. Initial results with hydrophobic precursors can produce a significant improvement in warm-moisture resistance, demonstrating higher strength values ​​than the reference without storage. The precursors used were octyltriethoxysilane (OCS), (3-glycidyloxypropyl)trimethoxysilane (GLYMO), and hexamethyldisiloxane (HMDSO). By modifying the plasma parameters (power, distance, speed, and pulse cycle time), it is possible to influence the organic content of the applied layer. When deactivating adhesives, the parameter selection is deliberately geared to the total conversion of the precursor in order to remove the predominantly organic content for a glassy layer through plasma polymerization. Here, the opposite goal is pursued: to achieve a high level of hydrophobicity.In addition, the flow rate of the precursor was increased.

[0116] Coatings with atmospheric pressure plasma, for example, in the case of HMDSO, result in glassy layers on the substrate. However, with suitable parameter control (pulse width modulation), it is possible to influence the conversion of the HMDO. A pure SiOx layer is not to be expected with this polymerization. The proportion of carbon due to unreacted hydrocarbon chains from the precursor molecule (in the case of HMDSO, the hexamethyl chain) can be up to 12% by weight of the coating. This leads to hydrophobization. This non-hydrophilic layer leaves the adhesive tape sides and the bonding interfaces free of water due to the beading of water droplets. Ultimately, the liquid medium is carried away from the zone of influence where the negative effect on adhesion occurs, and migration cannot occur due to the polarity (see film with hydrophobized cellulose and without treatment).

[0117] Fig. 2This bar graph shows the bond strength of ACX plus< 6812 to polypropylene (PP) after three days (3d) at room temperature (RT) and after three days at 40°C and 100% relative humidity. The two left-hand bars show no passivation of the side edges, while the right-hand bars show passivation. The bond strength was determined at a peel angle of 90°. A significant increase in bond strength is evident due to the passivation of the side edges. This effect is particularly pronounced at high humidity.

[0118] The dashed line in the bar graph represents the bond strength during cohesive splitting of the bond. Bond strength exceeding the dashed line above is due to different measurement setups, measurement errors, etc. In any case, the bar graph clearly shows that plasma wall encapsulation leads to significantly increased bond strength, particularly enabling longer storage.

[0119] Edge encapsulation reduces the barrier function against migratory substances, especially against gas diffusion, as the following table shows:

[0120] The HMDSO treatment is an example of a treatment for siloxane-containing precursors. The treatment was carried out using the aforementioned plasma nozzle: generator FG 5001, fixed nozzle 216028WE from Plasmatreat. The results show that permeability can be significantly reduced by plasma treatment. List of reference symbols

[0121] 1Plasma nozzle 2Precursor unit 3Plasma unit 4Precursor 6Carrier gas 7Plasma 8Nozzle head 9Inlet 11Process gas 12Aperture 13Discharge zone 14Electrode tip 16Earthed stainless steel housing 17Side inlet 18Evaporator 19Precursor gas 20Adhesive layer

Claims

1. Method for reducing rearward infiltration of moisture into an adhesive bond, by adhering an adhesive tape with a layer (20) of adhesive to a substrate surface and, by means of a plasma stream, applying a hydrophobic passivation layer externally along one side edge of the layer (20) of adhesive, wherein a precursor (4) is supplied to the plasma stream and the precursor (4) used comprises silanes and / or siloxanes and the precursor (4) is selected from the group of aminopropyltriethoxysilane, perfluorooctyltriethoxysilane and HMDSO.

2. Method according to Claim 1, characterized in that the precursor (4) is evaporated and transported into the plasma stream by means of an inert gas.

3. Method according to at least one of the preceding claims, characterized in that a process gas (11) is excited and ambient air is used as process gas (11).

4. Method according to at least one of the preceding claims, characterized in that the layer (20) of adhesive comprises at least an elastomer and a reactive resin.

5. Method according to Claim 4, characterized in that the elastomer is selected from the group of vinylaromatics, methyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate and isobornyl acrylate or from the group of polyethers, or from the group of polydienes, or polyisoprene, semi- hydrogenated or hydrogenated polydienes, or polybutylene-butadiene, polybutylene, polyisobutylene, polyalkyl vinyl ethers, and polymer blocks of α,β-unsaturated esters.

6. Method according to at least one of the preceding claims, characterized in that the layer (20) of adhesive used comprises a pressure-sensitively tacky soft phase.

7. Method according to Claim 6, characterized in that the pressure-sensitively tacky soft phase used comprises a pressure-sensitively tacky polymer foam which comprises one or more polyacrylates.

8. Method according to Claim 7, characterized in that the polyacrylates comprise: (a) acrylic esters and / or methacrylic esters of the following formula         CH2=C(RI)(COORII) where RI = H or CH3 and RII is an alkyl radical having 4 to 14 carbon atoms, (b) olefinically unsaturated monomers having functional groups of the type already defined for reactivity with epoxide groups, (c) further acrylates and / or methacrylates and / or olefinically unsaturated monomers which are copolymerizable with component (a).