REDUCING THE SIDE EDGE ADHESION OF A DIP TAPE ROLL

Description

[0001] The invention relates to a method for reducing the winding mirror stickiness of an adhesive tape roll and to an adhesive tape roll.

[0002] For adhesive tape rolls, especially ACX plus< -range (the ACX plus< -range of tesa includes foamed adhesive tapes with acrylate-based adhesives), it has proven disadvantageous that the side edges tend to stick together when stacked or when in contact with other objects. To counteract this undesirable effect, siliconized side discs are typically placed on the winding surface of the roll. ACX plus< Products are used for safety reasons two side windows per roll, filmicFor conventional adhesive tapes (conventional adhesive tapes with a film carrier to which an adhesive is applied), only one side panel is sufficient. This also prevents contamination from particles that bond to the pressure-sensitive adhesive during transport or processing. When using such side panels, they must be cut to size to match the roll size and packaging. For both machine and manual processing, the side panel must be removed and placed back on the winding surface after use. Overall, the use of siliconized side panels involves a considerable amount of work.

[0003] There are already various solutions for deactivating side edge stickiness.

[0004] The side edge is treated with a pressure powder coating, so that applied talc or glass beads lead to a reduction in adhesive strength. This process has a detrimental effect on the optical properties of the adhesive tape roll. Furthermore, contamination from weakly adhering talc particles occurs, which is undesirable in many applications. At the same time, long-term stability of the deactivation is not guaranteed, as the applied particles sink into the adhesive at higher temperatures or are surrounded by it.

[0005] Another solution is to coat the side edge with a conventional varnish. This process requires very long drying times. At the same time, higher roll forces are observed for large application quantities of, for example, 3 g / m². Adding water to the varnish reduces film formation, allowing the roll forces to be reduced to normal levels.

[0006] WO 2008 / 095653 A1 describes a process for passivating the edge of pressure-sensitive adhesive tapes. The passivation occurs through physical or chemical crosslinking of the pressure-sensitive adhesive on the edge or through the physical or chemical degradation of the pressure-sensitive adhesive structures responsible for the adhesive effect. This is achieved by applying a crosslinker to the side edge with subsequent UV or IR irradiation, electron beam irradiation, gamma irradiation, or plasma treatment. Crosslinkers disclosed include epoxides, amines, isocyanates, peroxides, or polyfunctional silanes. A disadvantage is the relatively complicated and complex setup of the process.

[0007] EP 1 373 423 describes a method for deactivating the adhesive layer of the edge surface of an adhesive tape roll, in which radiation-chemically crosslinkable acrylates, acrylate oligomers and acrylate prepolymers are applied and cured with ionising and electromagnetic radiation.

[0008] US 2010 / 004 47 530 describes a method for coating the side edges of an adhesive tape roll, which uses an indirect application method using radiation-curable lacquers or hot-melt polymers.

[0009] EP 1 129 791 A2 describes a process for producing anti-adhesive coatings in which the anti-adhesive layer is applied to the web-like material by low-pressure plasma polymerization, whereby the web-like material is continuously drawn through a plasma zone containing a low-pressure plasma. The anti-adhesive coatings formed by plasma polymerization are particularly suitable for adhesive tape backings and release liners.

[0010] The above-mentioned methods are only suitable to a limited extent for reducing the adhesive strength of the winding surface of an adhesive tape roll.

[0011] WO 2013 / 039737 A2 describes a method for reducing the stickiness of an edge surface of a rolled substrate, such as a roll of adhesive tape. The stickiness reduction is achieved using a radiation source with a radiation output at a wavelength of less than 200 nanometers.

[0012] It is therefore an object of the invention to provide an improved method which reduces the pressure-sensitive adhesiveness of the winding surface of an adhesive tape roll, and it is an object of the invention to provide an adhesive tape roll with reduced pressure-sensitive adhesiveness.

[0013] With regard to the method, the problem is solved by a method having the features of claim 1.

[0014] According to the invention, a precursor containing organic polyfunctional silanes is fed into an atmospheric-pressure plasma stream. The plasma stream enriched with the precursor is directed onto a wound mirror, and the wound mirror is coated with a SiOx coating. Advantageously, the plasma stream enriched with the precursor is directed directly onto the wound mirror, so that the wound mirror is immediately and directly coated with a SiOx coating.

[0015] It has surprisingly been found that a plasma coating process can be applied directly to the winding surface of a roll of adhesive tape. The adhesive tape roll is a wound adhesive tape whose length is significantly greater than its width and whose width in turn is significantly greater than its thickness. In its simplest embodiment, the adhesive tape consists of a single, in particular foamed, layer of adhesive. The adhesive tape furthermore has at least one substrate web and a pressure-sensitive adhesive web applied to the substrate web. It is of course also possible for further webs or layers to be provided between the substrate and the pressure-sensitive adhesive web. However, it is essential for the invention that when the adhesive tape is wound onto a roll of adhesive tape, the narrow sides of the pressure-sensitive adhesive web are exposed between the substrate webs and can adhere to other objects or absorb dirt.The end face of the sequence of wound substrate webs and pressure-sensitive adhesive webs, which may be alternating, is referred to as the wound mirror. The SiOx coating is preferably applied over the entire surface of the wound mirror. Advantageously, the coating is of constant thickness across the entire length of the wound mirror. The coating is preferably between 60 nm and 600 nm thick, and more preferably, the thickness is between 100 nm and 200 nm.

[0016] Adhesive tape rolls are preferably manufactured by first producing a very wide tape roll, with widths up to 2,000 mm. This wide tape roll is then cut into tape rolls. The cut tape rolls have particularly sticky ends.

[0017] In a further development of the invention, a master roll is cut transversely to the longitudinal axis into separate adhesive tape rolls, and the winding surfaces of the separate adhesive tape rolls are first passivated with the SiOx coating. One, two, or any higher number of adhesive tape rolls can then even be unwound and rewound in a traversing manner. Traversing winding initially involves unwinding a narrow adhesive tape from an equally narrow adhesive tape roll, with the narrow adhesive tape then being wound in a traversing manner onto a significantly longer winding axis so that the adhesive tape layers not only lie directly on top of one another, but are initially wound next to one another along the winding axis until a first winding layer is wound up, and then a second winding layer is wound up in the opposite direction on the winding axis.

[0018] The invention is achieved with regard to the adhesive tape roll by an adhesive tape roll having the features of claim 7.

[0019] The adhesive tape roll is preferably produced by one of the above-mentioned processes and is characterized by at least one, preferably exactly two, winding mirrors, to which a SiOx coating is applied over the entire surface, advantageously using a plasma process. The SiOx coating can have a thickness of 60 nm to 600 nm, preferably between 100 nm and 200 nm, and it is preferably applied in a constant layer thickness over the entire extent of the winding mirror.

[0020] The adhesive tape rolls are in particular those of the ACX plus< -range from tesa.

[0021] Such adhesive tapes 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).

[0022] "Polyurethanes" are broadly understood to mean polymeric substances in which repeating units are linked together by urethane groups -NH-CO-O-.

[0023] "Polyolefins" are polymers that contain at least 50% repeat units of the general structure -[-CH2-CR1 R2-]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).

[0024] 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.

[0025] 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 points 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.

[0026] Such adhesive tapes may further comprise a 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.

[0027] In the simplest version, the adhesive tape consists only of a soft phase.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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(RI< )(COOR II< ) where RI< = H or CH 3 and R II< is an alkyl radical having 4 to 14 C atoms, b) olefinically unsaturated monomers with 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).

[0040] 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.

[0041] 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.

[0042] 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.

[0043] For component (b), monomers with functional groups selected from the group consisting of: hydroxyl, carboxy, sulfonic, or phosphonic acid groups, acid anhydrides, epoxides, and amines are preferably used. 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, itaconic acid, maleic anhydride, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 6-hydroxyhexyl methacrylate, allyl alcohol, glycidyl acrylate, and glycidyl methacrylate.

[0044] In principle, any vinyl-functionalized compounds that are copolymerizable with component (a) and / or component (b) can be used as component (c). The monomers of component (c) can be used to adjust the properties of the resulting pressure-sensitive adhesive. Examples of monomers of component (c) are:

[0045] 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-Butoxyethylmethacrylat, 2-Butoxyethylacrylat, 3,3,5-Trimethylcyclohexylacrylat, 3,5-Dimethyladamantylacrylat, 4-Cumylphenylmethacrylat, Cyanoethylacrylat, Cyanoethylmethacrylat, 4-Biphenylacrylat, 4-Biphenylmethacrylat, 2-Naphthylacrylat, 2-Naphthylmethacrylat, Tetrahydrofufurylacrylat, Diethylaminoethylacrylat, Diethylaminoethylmethacrylat, Dimethylaminoethyl-acrylat, Dimethylaminoethylmethacrylat, 2-Butoxyethylacrylat, 2-Butoxy¬ethylmethacrylat, 3-Methoxyacrylsäuremethylester,3-Methoxybutylacrylat, Phenoxyethylacrlylat, Phenoxyethylmethacrylat, 2-Phenoxyethylmethacrylat, Butyldiglykolmethacrylat, Ethylenglycolacrylat, Ethylenglycolmonomethylacrylat, Methoxy Polyethylenglykolmethacrylat 350, Methoxy Polyethylenglykolmethacrylat 500, Propylenglycolmonomethacrylat, Butoxydiethylenglykolmethacrylat, Ethoxytriethylenglykolmethacrylat, Octafluoropentylacrylat, Octafluoropentylmethacrylat, 2,2,2-Trifluoroethylmethacrylat, 1,1,1,3,3,3-Hexafluoroisopropylacrylat, 1,1,1,3,3,3-Hexafluoroisopropylmethacrylat, 2,2,3,3,3-Pentafluoropropylmethacrylat, 2,2,3,4,4,4-Hexafluorobutylmethacrylat, 2,2,3,3,4,4,4-Heptafluorobutylacrylat, 2,2,3,3,4,4,4-Heptafluorobutylmethacrylat, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluorooctylmethacrylat, Dimethylaminopropylacrylamid, Dimethylaminopropylmethacrylamid, N-(1-Methylundecyl)acrylamid, N-(n-Butoxymethyl)acrylamid, N-(Butoxymethyl)methacrylamid, N-(Ethoxymethyl)acrylamid, N-(n-Octadecyl)acrylamid, weiterhin N,N-dialkyl-substituted amides, such as N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-benzyl-acrylamide, 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).

[0046] 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.

[0047] 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.

[0048] 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).

[0049] 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.

[0050] Suitable solvents for the preparation of the polyacrylates are alcohols such as methanol, ethanol, n- and iso-propanol, n- and iso-butanol, preferably isopropanol and / or isobutanol, as well as 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 as well as 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.

[0051] 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).

[0052] 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.

[0053] The weight-average molecular weights MW 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 MW 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 the eluent. The measurement was carried out at 25 °C. The pre-column used was PSS-SDV, 5 µm, 10 3< Å, ID 8.0 mm × 50 mm. 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 was 1.0 ml per minute. It was measured against PMMA standards.

[0054] The weight-average molecular weight M w is determined by gel permeation chromatography (GPC). THF with 0.1 vol% trifluoroacetic acid is used as the eluent. The measurement is carried out at 25 °C. The precolumn is PSS-SDV, 5 µ, 10 3< Å, ID 8.0 mm × 50 mm. The columns PSS-SDV, 5 µ, 10 3< Å, 10 5< Å, and 10 6< Å, each with ID 8.0 mm × 300 mm, are used for separation. The sample concentration is 4 g / L, and the flow rate is 1.0 ml per minute. The measurement is carried out 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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).

[0060] 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.

[0061] The thermal crosslinker, for example the trimerized isocyanate, is preferably used 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.

[0062] 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.

[0063] 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).

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] Amino alcohols are also preferred as accelerators. Secondary and / or tertiary amino alcohols are particularly preferred, with at least one, preferably all, of the amine functionalities being secondary and / or tertiary in the case of multiple amine functionalities per molecule. Preferred amino alcohol accelerators that can be used are triethanolamine, N,N-bis(2-hydroxypropyl)ethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, 2-aminocyclohexanol, bis(2-hydroxycyclohexyl)methylamine, 2-(diisopropylamino)ethanol, 2-(dibutylamino)ethanol, N-butyldiethanolamine, N-butylethanolamine, 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)-1,3-propanediol, 1-[bis(2-hydroxyethyl)amino]-2-propanol, triisopropanolamine, 2-(dimethylamino)ethanol, 2-(diethylamino)ethanol, 2-(2-dimethylaminoethoxy)ethanol, N,N,N'-trimethyl-N'-hydroxyethylbisaminoethyl ether, N,N,N'-trimethylaminoethylethanolamine and / or N,N,N'-trimethylaminopropylethanolamine.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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 remains intact, a closed-cell foam is created.

[0074] 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).

[0075] 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 ethylene-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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] Optionally, the soft phase of the adhesive tape can 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.

[0080] Furthermore, flame-resistant 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; anti-aging agents, light stabilizers, ozone protectants and / or compounding agents can be included in the soft phase. Preferably, both primary, e.g., 4-methoxyphenol or Irganox®< 1076, and secondary anti-aging agents, 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] In another specific embodiment, the adhesive tape consists, in the order 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, i.e., the side facing the substrate, of the soft phase can be covered with a release liner; however, this is not considered part of the adhesive tape.

[0088] The adhesive tapes are preferably foamed acrylate masses, in particular of the type described above, which may additionally have one (or more) intermediate carriers.

[0089] The method according to the invention can be used particularly advantageously to reduce the adhesiveness of the winding surface of an adhesive tape roll when the winding surface of the adhesive tape roll is contaminated.

[0090] Such contamination of the winding surface often occurs during the cutting process, especially when individual rolls of adhesive tape are cut in a plate-like manner from a parent roll. Cutting aids, such as oils or water, are then used for the cutting process. These cutting aids are found on the winding surfaces.

[0091] Adhesive tapes are usually manufactured by unwinding a wide roll of backing material and then coating it with an adhesive. This adhesive can then be covered with a liner. After any further processing steps, such as drying, the backing material coated with adhesive, called the adhesive tape web, is wound up together with the liner into a so-called parent roll. For cutting, the parent roll is unwound and the liner-coated adhesive tape web is fed into a corresponding cutting device in which the adhesive tape web is cut into individual adhesive tapes, which are then usually wound onto cores made of cardboard or plastic, for example. Cutting can also take place directly after production, i.e. without the adhesive tape web and liner being wound and unwound again.

[0092] In addition, adhesive tapes are produced by cutting adhesive tape rolls directly from a jumbo or master roll.

[0093] It is also possible to cut the adhesive tape strip without a liner and to apply the liner in the appropriate width to the open adhesive side after the cutting process.

[0094] A relevant parting-off machine is described, for example, in EP 1 436 112 A1.

[0095] Surprisingly, a contaminated wound mirror can be passivated to the same quality as a non-contaminated wound mirror.

[0096] The invention is described using an embodiment in two figures, in which: Fig. 1 shows a basic structure of a plasma nozzle used, Fig. 2 shows a winding mirror of an adhesive tape roll provided with a SiOx coating.

[0097] Fig. 1shows the basic view of a plasma nozzle 1, which is an OpenAir system of the Plasmatreat GmbH.

[0098] The plasma nozzle 1 comprises a precursor unit 2, which is located in the Fig. 1 shown 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.

[0099] 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.

[0100] 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 can be used as the precursor 4, for example, octyltriethoxysilane (OCS), (3-glycidyloxypropyl)trimethoxysilane (GLYMO), and hexamethyldisiloxane (HMDSO).

[0101] Precursor 4 used here is hexamethyldisiloxane (HMDSO), which is added to the carrier gas in quantities of 10, 20, 40, and up to 150 grams per hour. The temperature in evaporator 18 is approximately 120 °C, thus above the boiling point of HMDSO, which is approximately 100 °C.

[0102] 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 6 thus reaches a wound mirror 20 with the plasma 7.

[0103] In the Fig. 2 A roll of adhesive tape 21 is shown with one of the two winding mirrors 20. The roll of adhesive tape 21 consists of a rolled-up adhesive tape, which in turn has a substrate web 22, to which a pressure-sensitive adhesive is applied over the entire surface on one side as a pressure-sensitive adhesive web 23. The substrate web 22 can be a film, a fabric, or a paper.

[0104] The substrate web 22 and the pressure-sensitive adhesive web 23 together form the adhesive tape, which Fig. 2 is rolled up. The substrate web 22 is usually manufactured and supplied in widths of 500 mm to 2,000 mm and is also coated with the pressure-sensitive adhesive in this width. The substrate web 22 is wound up together with the pressure-sensitive adhesive web 23 formed on it, so that a wide adhesive tape roll is created, also in a width of 500 mm to 2,000 mm. Only then is the wide adhesive tape roll cut onto adhesive tape rolls 21 of the desired working width. After the cutting process, the pressure-sensitive adhesive on the cut edges of the adhesive tape rolls 21, in particular the pressure-sensitive adhesive webs 23, is exposed and, due to its adhesive properties, can make further processing and product use difficult or even impossible.

[0105] The changing mirror 20 of the Fig. 2is characterized by an alternating sequence of substrate webs 22 and pressure-sensitive adhesive webs 23. In embodiments of the adhesive tape roll 21, the adhesive tape has a very small ratio of the thickness of the substrate web 22 to the thickness of the pressure-sensitive adhesive web 23. In such adhesive tapes, which are referred to as thick-film products, viscoelastic materials with their own adhesive properties are often used for the substrate webs 22, so that almost the entire winding surface 20 of the adhesive tape roll 21 is adhesive. The pressure-sensitive adhesiveness of the winding surface 20 means that, after contact with other objects, the adhesive tape roll 21 is destroyed or deformed upon removal, or is no longer usable. This is particularly a problem with narrow rolls, which have only low mechanical strength.

[0106] The adhesive strength of the wound mirror 20 is reduced by applying a passivation layer. According to the invention, the passivation layer is a SiOx coating, which is applied with the aid of the Fig. 1 The plasma nozzle 1 shown is applied over the entire surface of the winding mirror 20 in a plasma process.

[0107] The plasma nozzle 1 is at a perpendicular angle to a surface of the winding mirror 20 and opens into the nozzle head 8, wherein the winding mirror 20 rests on a rotating table, not shown.

[0108] The treatment of the wound mirror 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, which forms the actual silicon oxide layer on the surface of the wound mirror 20, is then fed to the process gas 11 in the nozzle head 8 via a gas-conducting channel via the lateral inlet 17. Example 1:

[0109] In this example, hexamethyldisiloxane (HMDSO) is added to the process gas 11 as precursor 4, which is excited in the process gas 11 and thereby significantly increases its reactivity. As a result, SiOx optimally deposits on the surface of the wound mirror 20 and binds firmly. In the present examples, wound mirrors 20 are made of so-called ACX plus< Rolls whose side edge stickiness is to be reduced are considered. First, not the winding surface 20 itself, but a rag sample is treated using the plasma process described above. The test setup includes the following parameters, conditions, and technical data to be considered: Material to be treated: ACX plus< - 7056 as Lappenmuster Plasma nozzle: Generator FG 5001, fixed nozzle 216028WE Precursor: Hexamethyldisiloxane (HMDSO) Precursor quantity: 10, 20, 40 g / hour Number of treatments: 1 to 3 times Treatment speed: 40 m / min for flat KM surfaces Nozzle distance: 15 mm PCT (Pulse Cycle Time): 20% and 100%

[0110] The PCT value controls the glass-like appearance of the silane layer.

[0111] PCT (Pulse Cycle Time) refers to the modulation of the plasma discharge by pulses. Switching the discharge on and off can improve the service life of the electrode tips 14 and influence the formation of reactive species. 100 percent corresponds to a continuous discharge.

[0112] Table 1 shows the tack results of untreated and treated ACX plus< -7056 flap samples in the Proptec standard procedure.

[0113] The Proptec method is a method for measuring the instant bond strength, or tack, of an adhesive. This can be used as a quality indicator for passivation and can provide a quantified value.

[0114] tesa ®< ACX plus< 7056 is a transparent, linerless acrylic adhesive tape with a foamed, acrylic-based pressure-sensitive adhesive with a thickness of 1500 µm. One adhesive side of a ACX plus<coated rag coated with HMDSO, where the left column represents the amount of HMDSO applied per hour, the second column the speed at which the nozzle head 8 is moved over the rag, the third column the distance of the nozzle head 8 from the rag, and PCT the aforementioned pulse cycle time. Fmax indicates the maximum force required to remove the stamp pressed onto the rag, and the right column indicates the energy required for this.

[0115] The surface area of ​​the circular Proptec stamp is 25.4 mm, the stamp is pressed onto the rag with a force of 4.5 N for 1 second.

[0116] The 'Remarks' section shows how strongly the rag (KM) adheres to the stamp. The bottom line shows the reference of a ACX plus< coated flap without plasma-polymerized coating. It is clearly visible that compared to the untreated adhesive surface of the ACX plus<product, significant reductions in adhesive force are measurable. Adhesive force is also referred to as stickiness. The above measurements are also applicable to the winding mirror 20 of ACX plus< Roles transferable. In the treated ACX plus< The rollers not only do not stick to metallic substrates, but they can also be removed without any problems. In addition, the plasma polymerization layer has a dirt-repellent effect, as dust, fibers, and paper hardly stick to the adhesive. Even over a period of eight hours, no noticeable contamination of the nozzle components of plasma unit 3 by precursor 4 was detected. List of reference symbols

[0117] 1Plasma nozzle 2Precursor unit 3Plasma unit 4Precursor 6Carrier gas 7Plasma 8Nozzle head 9Inlet 11Process gas 12Aperture 13Discharge zone 14Electrode tip 16grounded stainless steel housing 17side inlet 18evaporator 19precursor gas 20Wrapping mirror 21Adhesive tape roll 22Substrate web 23Adhesive web

Claims

1. A method for reducing the roll end face tackiness of a roll of adhesive tape (21), wherein the adhesive tape forming the roll of adhesive tape (21) has at least one substrate web (22) and a web of pressure-sensitive adhesive (23) applied to the substrate web (22), in which a precursor (4) containing an organic polyfunctional silane is supplied to a stream of plasma, the stream of plasma enriched with the precursor (4) is directed onto the roll end face (20) and the roll end face (20) is coated with a coating of SiOx.

2. The method as claimed in claim 1, characterized in that a polyfunctional silane from the group: hexamethyldisiloxane (HMDSO), (3-glycidyloxypropyl)trimethoxysilane (GLYMO), octyltriethoxysilane (OCS) is used as the precursor (4) .

3. The method as claimed in claim 1 or 2, characterized in that a master roll is slit into individual rolls of adhesive tape transversely to the longitudinal direction and the roll end face of the separate rolls of adhesive tape are initially passivated with the SiOx coating and at least one of the separate rolls of adhesive tape (21) is unrolled and transverse wound.

4. The method as claimed in claim 1, 2 or 3, characterized in that the SiOx coating is applied with a thickness of between 60 nm to 600 nm.

5. The method as claimed in one of the preceding claims, characterized in that the SiOx coating is applied to the entire surface of the roll end face (20).

6. The method as claimed in one of the preceding claims, characterized in that the SiOx coating has a constant thickness over its entire extent.

7. A roll of adhesive tape manufactured in one of the methods defined above, with a roll end face (20), with a SiOx coating applied to the entire surface of the roll end face (20).

8. The roll of adhesive tape as claimed in claim 7, characterized in that the SiOx coating has a thickness of 60 nm to 600 nm.

9. The roll of adhesive tape as claimed in claim 8, characterized in that the SiOx coating has a constant thickness over its entire extent.

10. The roll of adhesive tape as claimed in at least one of claims 7 to 9, characterized in that the roll end face of the roll of adhesive tape is contaminated with slitting aid.