Adhesive tape for flying roll splices of flat web material

Abstract

A splicing adhesive tape should be provided that can be used for the flying splice of flat web materials in production environments with high cleanliness requirements, especially in clean rooms, and thus minimizes or even eliminates material emissions during splicing. This is achieved with an adhesive tape (K) for the flying splice of flat web material (RB) wound on rolls (R, B). The adhesive tape a splittable layer (K3) comprising two polymer layers (K31, K32) lying directly on top of one another, which form a predetermined breaking surface at their interface (A) for splitting the adhesive tape (K) over its entire surface; a first adhesive layer (K1) which is arranged on the side of the polymer layer (K31) facing away from the interface (A); and a second adhesive layer (K2) which is arranged on the side of the polymer layer (K32) facing away from the interface (A), includes.

Description

[0001] The invention relates to the technical field of adhesive tapes, as they are used in many areas of technology for temporarily or permanently covering or bonding a wide variety of substrates. More specifically, the invention relates to an adhesive tape that enables on-the-fly roll splices when processing flat web material wound on rolls. The adhesive tape comprises a splittable layer, which is essentially formed by two polymer layers and can be supplemented by additional layers.

[0002] Flying splice is a common process, traditionally used in paper mills and the printing industry, and increasingly also in battery production, the packaging industry, and other sectors, for replacing an old, almost-used roll of flat web material, such as paper, with a new one without having to stop the high-speed machines. In a common process, an adhesive tape is used to create a bond between the first layer of the new roll and the remaining flat web material of the old roll. The adhesive tape also secures the first layer of the new roll to the subsequent layer.The adhesive tape bonded to the flat web material of the new roll is then deliberately split into two parts: One part of the adhesive tape with the first adhesive layer remains in a first area of ​​the flat web material, which is now bonded across both rolls, and the other part of the adhesive tape with the second adhesive layer remains in a second area of ​​the flat web material, spaced apart from the first area. For the purpose of splitting, the adhesive tape has a predetermined breaking point where a defined force is applied to tear the adhesive tape apart.

[0003] The initial section of the new roll of wound flat web material is initially applied to the first, upper adhesive layer of the usually double-sided adhesive tape; the second, lower adhesive layer is bonded to the subsequent layer of flat web material. This ensures that the outermost layer of the roll of flat web material is fixed to the roll and cannot unwind, enabling a clean connection between the material of the first and second rolls. The first section of the flat web material of the new roll only partially covers the first adhesive layer. The area of ​​the first adhesive layer not covered by the flat web material of the new roll is available for bonding the flat web material of the old roll, whereas the second adhesive layer adheres to the flat web material of the new roll.As soon as the new roll is to replace the old roll and the “flying roll change” occurs, the predetermined breaking surface of the adhesive tape should ensure a controlled and defined opening of the adhesive tape and thus a safe unwinding of the flat web material from the new roll.

[0004] The contact created between the two rolls of flat web material via the adhesive tape during a flying splice is referred to as a "splice" or "splice tape." The adhesive tapes used are often referred to as "splice tapes" or "splice adhesive tapes." Such adhesive tapes are generally known in the prior art and have been described in various forms.

[0005] EP 1 022 245 A2 describes an adhesive tape with an adhesive front side and a non-adhesive back side and two longitudinal edges for flying roll splice, with a) a paper carrier (P1) coated on one side on the front side with a self-adhesive mass (N1), wherein b) a part of the non-adhesive backing of the paper carrier (P1) is provided with a double-sided adhesive tape (DO), which on the one hand has a paper carrier (P2) made of split paper, which is coated on both sides with self-adhesive mass (N2, N3), wherein c) the double-sided adhesive tape (DO) is arranged at a distance (V) of 0.5 to 15 mm from one longitudinal edge of the adhesive tape.

[0006] EP 1 076 026 A2 describes the use of a fixing aid on the underside of a splice band for equipping a bale for flying splice, whereby a) the splice tape is glued to the second highest web of a wrapped bale using the fixing aid, and b) the splice tape is simultaneously glued to the beginning of the uppermost web of the wrapped bale in such a way that at least a part of the adhesive-coated upper side of the splice tape, which is opposite the fixing aid, is open for the adhesive coupling to a fast-moving web of another, unrolling bale, whereby c) the fixing aid is glued to the underside of the splice tape and consists of a carrier material formed from two flat materials laminated together, the lamination forming a predetermined breaking zone, and the fixing aid being provided with a pressure-sensitive adhesive on its underside.

[0007] EP 1 640 301 A1 relates to a splicing adhesive tape comprising a self-adhesive composition and a splittable system, wherein the splittable system comprises two layers which can be separated from one another.

[0008] EP 3 124 565 A1 describes an adhesive tape suitable for the flying roll change of flat web material wound on rolls, comprising a carrier layer having a first and a second surface, wherein on the side of the first surface of the carrier layer, a first adhesive layer is provided directly or indirectly over at least part of the surface, and wherein the second surface of the carrier layer has one or more surface areas on which a second adhesive layer is provided. The adhesive tape is characterized in that the adhesive tape has areas suitable for planar splitting ("predetermined breaking surfaces") in that at least the surface areas of the second surface of the carrier layer on which the second adhesive layer is provided are modified with a surface coating, wherein the adhesion forces of the lower adhesive layer to the surface coating are greater than the adhesion forces of the surface coating to the carrier layer, and / or wherein the adhesion forces of the lower adhesive layer to the surface coating are greater than the cohesion forces within the surface coating.

[0009] EP 3 460 017 A1 describes an adhesive tape (K) for the flying roll change of flat web material (RB) wound on rolls (R, B), with a carrier layer (K3) which has a first surface (K31) and a second surface (K32) opposite the first surface (K31), a first adhesive layer (K1) which is arranged directly or indirectly on the first surface (K31) of the carrier layer (K3) over at least part of its area, a second adhesive layer (K2) which is arranged on at least one surface region (FB) of the second surface (K32) of the carrier layer (K3), and at least one predetermined breaking surface for splitting the adhesive tape (K), wherein the predetermined breaking surface is designed such that the at least one surface region (FB) has a surface coating (K4) which is arranged between the carrier layer (K3) and the second adhesive layer (K2), wherein the adhesion forces of the second adhesive layer (K2) to the surface coating (K4) are greater than the adhesion forces of the surface coating (K4) to the carrier layer (K3), and / or wherein the adhesion forces of the second adhesive layer (K2) to the surface coating (K4) are greater than the cohesion forces within the surface coating (K4), characterized in that the second adhesive layer (K2) has a deactivated adhesive area (K6) on a surface (K21) facing in the direction of the carrier layer (K3).

[0010] Conventional splicing tapes contain paper-based slitting systems. When these tapes are used in production environments with stringent cleanliness requirements, the emission of paper particles and fibers caused by the paper-based slitting systems during flying roll changes proves to be extremely disruptive. In many cases, splicing tapes with paper-based slitting systems cannot be used in clean rooms and similarly demanding production environments, such as those required for the manufacture or processing of transparent materials, battery components (risk of short circuits due to contaminants such as paper fibers), or medical materials.

[0011] There is therefore a need for splicing tapes whose use greatly minimizes material emissions and, at best, eliminates them.

[0012] It was an object of the invention to provide a splicing adhesive tape that can be used for the flying roll change of flat web materials in production environments with high demands on cleanliness, in particular in clean rooms, and accordingly causes minimized or no material emission during splitting.

[0013] A further object of the invention was to provide an adhesive tape with a splitting force level suitable for flying splices, so that flying splices can be performed reliably. To this end, the adhesive tape must split under the given conditions of flying splices and exhibit sufficient initial splitting and tear resistance.

[0014] A further task was to adjust the splitting force level so that it is achieved stably during use even after prolonged storage of the adhesive tape.

[0015] A first and general subject matter of the invention, with which these objects are achieved, is an adhesive tape (K) for the flying roll change of flat web material (RB) wound on rolls (R, B), wherein the adhesive tape a splittable layer (K3) comprising two polymer layers (K31, K32) lying directly on top of one another, which form a predetermined breaking surface at their interface (A) for splitting the adhesive tape (K) over its entire surface; a first adhesive layer (K1) which is arranged on the side of the polymer layer (K31) facing away from the interface (A); and a second adhesive layer (K2) which is arranged on the side of the polymer layer (K32) facing away from the interface (A), includes.

[0016] Embodiments that are designated as preferred below are combined in particularly preferred embodiments with features of other embodiments designated as preferred. Combinations of two or more of the embodiments designated as particularly preferred below are therefore particularly preferred. Likewise preferred are embodiments in which a feature of one embodiment designated as preferred to any extent is combined with one or more further features of other embodiments designated as preferred to any extent.

[0017] To the extent that both specific amounts or proportions of an element and preferred embodiments of the element are disclosed below, the specific amounts or proportions of the preferably configured elements are also disclosed. Furthermore, it is disclosed that, with the corresponding specific total amounts or total proportions of the elements, at least some of the elements can be preferably configured, and in particular that preferably configured elements can in turn be present in the specific amounts or proportions within the specific total amounts or total proportions.

[0018] Flat web materials which can be processed with the aid of an adhesive tape according to the invention are preferably selected from papers, nonwovens, fabrics and films, in particular polymer films.

[0019] The adhesive tape (K) according to the invention comprises a splittable layer (K3). The splittable layer (K3) is the area of ​​the adhesive tape according to the invention where, during a flying roll change, the adhesive tape connected to the flat web material of the old and the new roll splits. As a result of this split, one section of the adhesive tape adheres to the end of the old roll and the other section to the beginning of the new roll – this section thus connects the two rolls of flat web material. The other section of the adhesive tape resulting from the split remains at a point on the new material web that is spaced from the beginning of the roll and is therefore slightly indented.

[0020] According to the invention, the cleavable layer (K3) comprises two polymer layers (K31, K32) lying directly on top of one another, which form a predetermined breaking surface at their interface (A) for the planar splitting of the adhesive tape (K). The invention therefore provides for an adhesive separation of the two polymer layers. “Adhesive separation” means that the separation occurs between the two polymer layers (K31, K32) and not within one of the two polymer layers. After separation, the polymer layers are therefore essentially separate from one another, in particular separate from one another. However, this does not rule out the possibility that minor amounts or traces of the respectively cleaved polymer layer may still adhere to the other polymer layer; these are considered insignificant.

[0021] Preferably, the polymers of the polymer layers (K31) and (K32) are immiscible with one another. This is particularly advantageous when the cleavable layer (K3) is produced by coextrusion. This could lead to intermixing of the polymers in the region of the interface, which in turn would make cleavage more difficult or even impossible, or at least would make the splitting force no longer precisely adjustable. "Immiscible" here means that there is a defined interface between two directly superimposed layers of the respective polymers, even in the softened or molten state, at which interface one material can be clearly distinguished from the other.

[0022] Preferably, one of the polymer layers (K31) and (K32), in particular the polymer layer (K32), comprises a total of at least 80 wt. %, more preferably a total of at least 90 wt. %, in particular a total of at least 95 wt. %, very particularly preferably a total of at least 98 wt. %, in each case based on the total weight of the layer in question, one or more polymers selected from the group consisting of polyesters, polyolefins and polyamides, more preferably from polyesters and polyolefins, in particular from polyesters. More preferably, one of the polymer layers (K31) and (K32), in particular the polymer layer (K32), is a film selected from the group consisting of polyester films, polyolefin films and polyamide films, more preferably from polyester films and polyolefin films, in particular from polyester films.Particularly preferably, one of the polymer layers (K31) and (K32), in particular the polymer layer (K32), is a film selected from the group consisting of biaxially stretched polyester films, mono- or biaxially stretched polyolefin films and biaxially stretched polyamide films, in particular biaxially stretched polyester films and biaxially stretched polyolefin films, very particularly preferably biaxially stretched polyester films.

[0023] Particularly advantageously, one of the polymer layers (K31) and (K32), in particular the polymer layer (K32), is selected from the group consisting of monoaxially oriented polypropylene films, biaxially oriented polypropylene films, biaxially stretched polyamide films, biaxially stretched polyethylene naphthalate films, biaxially stretched polyethylene terephthalate films and biaxially stretched polyethylene furanoate films. In particular, one of the polymer layers (K31) and (K32), in particular the polymer layer (K32), is selected from the group consisting of biaxially stretched polyethylene naphthalate films, biaxially stretched polyethylene terephthalate films and biaxially stretched polyethylene furanoate films. Very particular preference is given to one of the polymer layers (K31) and (K32), in particular the polymer layer (K32), being a biaxially stretched polyethylene terephthalate film. Additionally preferably, the material of the aforementioned films comprises more than 50 wt.-%, more preferably more than 75 wt.%, in particular more than 85 wt.% and most preferably completely recycled, i.e. has already undergone at least one use-recycling cycle before being processed into the above-mentioned films.

[0024] The other of the polymer layers (K31) and (K32), in particular the polymer layer (K31), is preferably a polyurethane layer, a polystyrene layer, a polyamide layer, a polybutylene terephthalate layer or a layer of a mixture of polystyrene and a styrene-butadiene copolymer.

[0025] Particularly preferably, the other of the polymer layers (K31) and (K32), in particular the polymer layer (K31), is a polyurethane layer or a polyamide layer.

[0026] If the other of the polymer layers (K31) and (K32), in particular the polymer layer (K31), is a polyamide layer, it preferably contains two polyamides. More preferably, the polyamide layer has an application weight of 2 to 4 g / m 2 More preferably, the polyamide layer is applied from an ethanolic-aqueous solution. In particular, the other of the polymer layers (K31) and (K32), in particular the polymer layer (K31), is a polyurethane layer.

[0027] The polyurethane of the polyurethane layer is preferably crosslinked. The crosslinker is preferably present in an amount of 0.5 to 10 wt.%, particularly preferably 1.0 to 8 wt.%, and in particular 1.5 to 5 wt.%, based in each case on the total weight of the polyurethane layer.

[0028] The polyurethane layer can basically be opaque, colored, optically clear or transparent.

[0029] The polyurethane layer is preferably formed by extrusion (TPU) or from a dispersion (PUD). The polyurethane layer can also be formed from a solution. "Formed" means that the material of the polyurethane layer is formed into the layered form, in which it then exists in the splittable layer (K3). Possible polyurethane layers, which differ in their production process, are described below: i) extrusion-moulded thermoplastic polyurethane-based polyurethane layer (TPU)

[0030] In a first embodiment, the polyurethane layer is based on thermoplastic polyurethane and has been formed by extrusion. Such a layer based on thermoplastic polyurethane typically refers to a layer whose proportion of thermoplastic polyurethane is at least 50% by weight. Preferably, the proportion of thermoplastic polyurethane in the polyurethane layer is at least 90% by weight; in particular, the polyurethane layer consists essentially of thermoplastic polyurethane.

[0031] The preferably crosslinked, thermoplastic polyurethane of the polyurethane layer is preferably polyester-based, but can alternatively also be polyether-based, for example, based on poly-THF as the polyol. The polyester-based or polyether-based thermoplastic polyurethane is typically thermoplastic polyurethane based on aliphatic polyester or aliphatic polyether. The glass transition temperature (Tg) of the soft molecular chain of the thermoplastic polyurethane is preferably between -20 °C and 40 °C, and the glass transition temperature of the hard molecular chain of the thermoplastic polyurethane is preferably between 60 and 110 °C. The thermoplastic polyurethane preferably has a tear strength of over 20, preferably over 35 MPa, and its Shore A hardness is preferably between 55 and 85, in particular between 55 and 70 or between 70 and 85.

[0032] The thermoplastic polyurethane is preferably a reaction product of a reaction mixture containing at least one diisocyanate, at least one polyester polyol or polyether polyol, at least one crosslinker, and optionally at least one chain extender. The polyester polyol or polyether polyol preferably has a melting temperature of at least 30°C, such as at least 100°C or at least 200°C. The choice of a suitable processing method, such as cooling conditions, can contribute to increasing the degree of crystallinity of the layer. The degree of crystallinity can be determined by differential scanning calorimetry (DSC) and is expressed as a fraction of the crystallinity in the thermoplastic polyurethane film.

[0033] The total proportion of diisocyanate in the reaction mixture is preferably 0.5 to 47 wt.%, more preferably 1 to 40 wt.%, and especially 10 to 25 wt.%. The amount of diisocyanate in the reaction mixture can also be expressed as an isocyanate index. An isocyanate index is generally understood to refer to the ratio of the equivalent amount of functional isocyanate groups used to the equivalent amount of functional hydroxy groups. The isocyanate index of the reaction mixture is preferably in a range from 0.99 to 1.20, such as from 1.00 to 1.10. The diisocyanate is preferably a diisocyanate having the structure according to formula (I) O=C=NRN=C=O (I), wherein R is selected from substituted or unsubstituted (C1-C40)alkylene, (C2-C40)alkenylene, (C4-C20)arylene, (C4-C20)arylene-(C1-C40)alkylene-(C4-C20)arylene, (C4-C20)cycloalkylene and (C4-C20)aralkylene. In further examples, the diisocyanate is selected from dicyclohexylmethane 4,4'-diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 1,4-phenylene diisocyanate, 1,3-phenylene diisocyanate, m-xylylene diisocyanate, toluene 2,4-diisocyanate, toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, poly(hexamethylene diisocyanate), 1,4-cyclohexylene diisocyanate, 4-chloro-6-methyl-1,3-phenylene diisocyanate, hexamethylene diisocyanate, diphenylmethane 4,4'-diisocyanate, 1,4-diisocyanatobutane, 1,8-diisocyanatooctane, 2,6-toluene diisocyanate, 2,5-toluene diisocyanate, 2,4-toluene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, Methylenebis(o-chlorophenyl diisocyanate), methylenediphenylene-4,4'-diisocyanate, (4,4'-diisocyanato-3,3',5,5'-tetraethyl)diphenylmethane, 4,4'-diisocyanato-3,3'-dimethoxy-biphenyl(o-dianisidine diisocyanate), 5-chloro-2,4-toluene diisocyanate, 1-chloromethyl-2,4-diisocyanatobenzene, tetramethyl-m-xylylene diisocyanate, 1,6-diisocyanatohexane, 1,12-diisocyanatododecane, 2-methyl-1,5-diisocyanatopentane, methylenedicyclohexylene-4,4'-diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 2,2,4-trimethylhexyl diisocyanate and a mixture of two or more of these compounds.

[0034] Particularly preferably, the at least one diisocyanate is diphenylmethane-4,4'-diisocyanate (MDI), hexane diisocyanate (HDI), isophorone diisocyanate (IPDI) or hexamethylene diisocyanate (HMDI).

[0035] The total proportion of polyester polyol or polyether polyol in the reaction mixture is preferably in the range of 43 wt% to 70 wt%, more preferably 50 wt% to 60 wt%.

[0036] The polyester polyol may contain any suitable number of hydroxy groups. For example, the polyester polyol may contain four hydroxy groups or three hydroxy groups. The polyester polyol may even contain two hydroxy groups, so that the polyester polyol is a polyester diol. In general, the polyester polyol may be a product of a condensation reaction, such as a polycondensation reaction. However, the polyester polyol is typically not produced via a ring-opening polymerization product.

[0037] In examples where the polyester polyol is prepared according to a condensation reaction, the reaction may take place between one or more carboxylic acids and one or more polyols. Examples of suitable carboxylic acids include carboxylic acids according to formulas (IIa) (dicarboxylic acids) and (IIb) (hydroxycarboxylic acids) having the structures: where R 1is selected from substituted or unsubstituted (C1-C40) alkylene, (C2-C40) alkenylene, (C4-C20) arylene, (C4-C20) cycloalkylene and (C4-C20) aralkylene;wherein R 2 is selected from substituted or unsubstituted (C1-C40) alkylene, (C2-C40) alkenylene, (C4-C20) cycloalkylene and (C4-C20) aralkylene.

[0038] Examples of suitable carboxylic acids include lactic acid (2-hydroxypropanoic acid), succinic acid (butanedioic acid), 3-hydroxybutanoic acid, 3-hydroxypentanoic acid, terephthalic acid (benzene-1,4-dicarboxylic acid), naphthalenedicarboxylic acid, 4-hydroxybenzoic acid, 6-hydroxynaphthalene-2-carboxylic acid, oxalic acid, malonic acid (propanedioic acid), adipic acid (hexanedioic acid), pimelic acid (heptanedioic acid), ethonic acid, suberic acid (octanedioic acid), azelaic acid (nonanedioic acid), sebacic acid (decanedioic acid), glutaric acid (pentanedioic acid), dodecanedioic acid, brassylic acid, thapsic acid, maleic acid, fumaric acid, glutaconic acid, 2-decenoic acid, muconic acid, glutic acid, citraconic acid, mesaconic acid, itaconic acid, malic acid (2-hydroxybutanedioic acid), aspartic acid (2-Aminobutanedioic acid), Glutamic acid (2-Aminopentanedioic acid), Tartaric acid, Tartaric acid (2,3-Dihydroxybutanedioic acid), Diaminopimelic acid, Saccharic acid, Mesoxalic acid, Oxaloacetic acid, Acetonicarboxylic acid (3-Oxopentanedioic acid), Arbinaric acid, Phthalic acid, Isophtic acid, 2,6-Naphthalenedicarboxylic acid and a mixture of two or more of the aforementioned compounds. The carboxylic acid is particularly preferably adipic acid.

[0039] The polyol is preferably a polyol according to formula (III) having the structure: HO - R 3 - OH (III), where R 3 is selected from substituted or unsubstituted (C1-C40) alkylene, (C2-C40) alkenylene, (C4-C20) arylene, (C1-C40) acylene, (C4-C20) cycloalkylene, (C4-C20) aralkylene and (C1-C40) alkoxylene.

[0040] For example, the diol may have a weight-average molecular weight in a range from 30 Daltons to 250 Daltons, preferably from 50 Daltons to 150 Daltons. The diol component may in principle contain any suitable number of carbon atoms. For example, the diol may have a number-average number of 2 carbon atoms to 50 carbon atoms, preferably 3 carbon atoms to 140 carbon atoms. Preferably, the diol is selected from ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, and a mixture of two or more of the aforementioned compounds.

[0041] Particularly preferred polyester polyols are, as above, polyalkylene adipates.

[0042] The TPU-based polyurethane layer is preferably free of additives such as antiblocking agents and waxes. Furthermore, the polyurethane preferably does not exhibit a crystalline superstructure, as manifested by a DSC peak > 210 °C. ii) dispersion-formed polyurethane layer (PUD)

[0043] In an alternative embodiment, the polyurethane layer is based on crosslinked polyurethane and formed from a dispersion. The proportion of polyurethane in such a polyurethane layer is preferably at least 50 wt.%, more preferably at least 90 wt.%. The polyurethane is preferably thermoplastic.

[0044] The polyurethane is preferably composed of at least one polyisocyanate component and at least one polyol component, ie it is preferably the reaction product of at least the components mentioned.

[0045] The polyurethane is particularly preferably an aliphatic polyester-polyurethane or an aliphatic polyether-polyurethane, i.e., in this case, the polyurethane is based on aliphatic polyester or aliphatic polyether. Likewise particularly preferably, the polyisocyanate component is aliphatic. In particular, the polyurethane is an aliphatic polyester-polyurethane, in particular based on ε-caprolactone and neopentyl glycol, or an aliphatic polyether-polyurethane, in particular based on polytetrahydrofuran, and the polyisocyanate component is aliphatic.

[0046] In principle, all known aliphatic, cycloaliphatic, araliphatic and preferably aromatic polyfunctional isocyanates can be used.

[0047] The at least one polyisocyanate component is preferably a diisocyanate; more preferably, it is selected from aromatic diisocyanates such as toluene diisocyanate (TDI), p-phenylene diisocyanate (PPDI), 4,4'-diphenylmethane diisocyanate (MDI), p,p'-bisphenyl diisocyanate (BPDI); aliphatic diisocyanates such as isophorone diisocyanate (IPDI), 1,6-hexamethylene diisocyanate (HDI), and 4,4'-diisocyanatodicyclohexylmethane (H12MDI), and diisocyanates with substituents in the form of halo, nitro, cyano, alkyl, alkoxy, haloalkyl, hydroxyl, carboxy, amido, and / or amino groups. In particular, the polyisocyanate component is toluene diisocyanate (TDI) or an aliphatic diisocyanate.

[0048] Specifically, the following may be mentioned as examples: alkylene diisocyanates having 4 to 12 carbon atoms in the alkylene radical, such as 1,12-dodecane diisocyanate, 2-ethyl-tetramethylene-1,4-diisocyanate, 2-methyl-pentamethylene-1,5-diisocyanate, tetramethylene-1,4-diisocyanate, and preferably hexamethylene-1,6-diisocyanate; cycloaliphatic diisocyanates such as cyclohexane-1,3-diisocyanate and cyclohexane-1,4-diisocyanate and any mixtures of these isomers, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), 2,4- and 2,6-hexahydrotoluene diisocyanate and any mixtures of these isomers, 4,4'-, 2,4'- and 2,2'-dicyclohexylmethane diisocyanate and any mixtures of these isomers, and preferably aromatic di- and polyisocyanates, such as 2,4- and 2,6-toluene diisocyanate and the corresponding isomer mixtures, 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate and the corresponding isomer mixtures, mixtures of 4,4'- and 2,4'-diphenylmethane diisocyanates,Polyphenylpolymethylene polyisocyanates, mixtures of 4,4'-, 2,4'-, and 2,2'-diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates (crude MDI), and mixtures of crude MDI and toluene diisocyanates. The organic di- and polyisocyanates can be used individually or as mixtures.

[0049] The polyisocyanate component preferably has a number-average molecular weight of 60 to 50,000 g / mol, in particular of 400 to 10,000 g / mol, preferably of 400 to 6,000 g / mol.

[0050] So-called modified polyfunctional isocyanates, i.e. products obtained by chemical conversion of organic di- and / or polyisocyanates, are also frequently used. Examples include di- and / or polyisocyanates containing ester, urea, biuret, allophanate, carbodiimide, isocyanurate, uretdione and / or urethane groups. Specifically, the following are suitable: organic, preferably aromatic, polyisocyanates containing urethane groups and having NCO contents of 33.6 to 15% by weight, preferably 31 to 21% by weight, based on their total weight. Examples are crude MDI or 2,4- or 2,6-tolylene diisocyanate modified with low molecular weight diols, triols, dialkylene glycols, trialkylene glycols or polyoxyalkylene glycols with number-average molecular weights of up to 6,000 g / mol, in particular up to 1,500 g / mol. Examples of suitable di- orPolyoxyalkylene glycols include diethylene, dipropylene, polyoxyethylene, polyoxypropylene, and polyoxypropylene-polyoxyethylene glycols, triols, and / or tetrols. Also suitable are NCO-containing prepolymers with NCO contents of 25 to 3.5 wt.%, preferably 21 to 14 wt.%, based on the total weight, prepared from polyester and / or preferably polyether polyols and 4,4'-diphenylmethane diisocyanate, mixtures of 2,4'- and 4,4'-diphenylmethane diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate, or crude MDI. Liquid polyisocyanates containing carbodiimide groups and / or isocyanurate rings and having NCO contents of 33.6 to 15% by weight, preferably 31 to 21% by weight, based on the total weight, for example based on 4,4'-, 2,4'- and / or 2,2'-diphenylmethane diisocyanate and / or 2,4- and / or 2,6-toluylene diisocyanate, have also proven useful.

[0051] The modified polyisocyanates can be mixed with each other or with unmodified organic polyisocyanates such as 2,4'-, 4,4'-diphenylmethane diisocyanate, crude MDI, 2,4- and / or 2,6-toluene diisocyanate.

[0052] Diphenylmethane diisocyanate isomer mixtures or crude MDI, and in particular crude MDI with a diphenylmethane diisocyanate isomer content of 30 to 55 wt.%, as well as urethane group-containing polyisocyanate mixtures based on diphenylmethane diisocyanate with an NCO content of 15 to 33 wt.%, have proven particularly suitable as isocyanates.

[0053] Preferred weight proportions of the polyisocyanate component are from 10 to 40 wt.%, in particular 13 to 35 wt.% and particularly preferably 15 to 30 wt.%, in each case based on the total weight of the polyurethane.

[0054] The term “polyol component” includes not only compounds with at least two hydroxyl groups, but generally compounds with at least two hydrogen atoms active towards isocyanates.

[0055] Preferably, the polyol component is a diol, more preferably a polyetherdiol, a polyesterdiol, a polycarbonatediol, a polycaprolactone polyol, or a polyacrylate polyol, with polyetherdiols, polyesterdiols, and polycarbonatediols being particularly preferred. In particular, the polyol component is selected from the group consisting of glycol, propanediol, butanediol, pentanediol, hexanediol, cyclohexanediol, cyclohexyldimethanol, octanediol, neopentyl glycol, diethylene glycol, triethylene glycol, trimethylpentanediol, benzenedimethanol, benzenediol, methylbenzenediol, bisphenol A, poly(butanediol-co-adipate) glycol, poly(hexanediol-co-adipate) glycol, poly(ethanediol-co-adipate) glycol, polytetramethylene glycol, polypropylene glycol, polyethylene glycol, polytetrahydrofuran, a diol of ε-caprolactone and neopentyl glycol, and mixtures of two or more of the above compounds.

[0056] The main function of the polyol component is to react with the polyisocyanate component to form the polyurethane polymer. However, the polyol component also serves as a physical conditioner, since the elasticity of the polyurethane depends on the molecular weight of the polyol component. Generally, the higher the molecular weight of the polyol component, the softer the resulting polyurethane. The polyol component preferably has a number-average molecular weight of 60 to 50,000 g / mol, in particular of 400 to 10,000 g / mol, and preferably of 400 to 6,000 g / mol.

[0057] The following dispersions can be used as polyurethane dispersions, either alone or in combination with each other: Anionically stabilized aliphatic polyester polyurethane dispersions (dispersions based on polyester and aliphatic anionic isocyanate polyurethane). These include the following products marketed by Covestro AG: Impranil® LP RSC 1380, DL 1537 XP, DL 1554 XP, Witcobond® 373-04 from Lanxess, or PERMUTEX® RU-92-410 from Stahl. Anionically stabilized aliphatic polyether polyurethane dispersions. These include the following products, marketed by Covestro AG: Impranil® 25 LP DSB 1069 or Witcobond® 386-53 from Lanxess; Anionically stabilized aliphatic polycarbonate-polyester-polyurethane dispersions. These include the following products, marketed by Covestro AG: Impranil® DLU or Permutex® EX-RU-92-600 from Stahl; Anionically stabilized polycarbonate polyurethane dispersions. These include the following products, distributed by Covestro AG: Impranil® DL 2288 XP.

[0058] These are polyurethane dispersions with a high solids content of preferably 30 to 70 wt.%, particularly preferably 50 to 60 wt.%. All of the above-mentioned products are typically free of organic cosolvents.

[0059] The polyurethane dispersions are preferably aqueous. They are preferably free of organic solvents, but they may optionally contain organic solvents.

[0060] To adjust the properties of the polyurethane layer to be produced, it may be advantageous for the starting mixture to further contain at least one further dispersion, preferably selected from the group consisting of polyurethane dispersions, in particular those whose polyol component has a comonomer with flame retardancy; synthetic rubber dispersions; natural rubber dispersions; and polyacrylate dispersions. This allows, among other things, the stability of the polyurethane layer and its elongation at break to be adjusted.

[0061] Polyacrylate dispersions contain water-insoluble polyacrylate, which is typically dispersed in water using an emulsifier. They contain, for example, approximately 30 to 60 wt.% polyacrylate and approximately 3 wt.% emulsifier. The polyacrylate is preferably a water-insoluble polyacrylate, polymethacrylate, mixtures thereof, or copolymers with other monomers. The emulsifier can be an ionic, non-ionic, or steric emulsifier. It is preferably not permanently incorporated into the polymer chains. Acrylate dispersions may contain other additives, such as film formers or co-solvents, defoamers, flame retardants, and / or wetting agents.

[0062] Acrylic dispersions are typically obtained by emulsion polymerization of suitable monomers. These are finely dispersed in water using an emulsifier. A water-soluble radical initiator is added to the emulsion of the monomers in water. Since the radicals formed from this radical dissolve preferentially in water, their concentration in the monomer droplets is preferably low, allowing polymerization to proceed very uniformly. After polymerization, the dispersion can be used directly, but it is often mixed with additives such as defoamers, film formers, and / or wetting agents to further improve its properties.

[0063] Optionally, the reaction of the OH groups of the polyol component with the isocyanate groups can be catalyzed. The following catalysts are particularly suitable: Organic metal compounds, preferably organic tin compounds, such as tin(II) salts of organic carboxylic acids, for example tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate, tin(II) laurate and the dialkyltin(IV) salts of organic carboxylic acids, for example dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, dioctyltin diacetate as well as tertiary amines such as triethylamine, tributylamine, dimethylcyclohexylamine, dimethylbenzylamine, N-methylimidazole, N-methyl-, N-ethyl-, N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutylenediamine, N,N,N',N'-tetramethylhexylene-1,6-diamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis- (dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo-[3.3.0]-octane, 1,4-diazabicyclo-[2.2.2]-octane, as well as alkanolamine compounds such as triethanolamine, tris-isopropanolamine, N-methyl- and N-ethyldiethanolamine and dimethylethanolamine.

[0064] Other suitable catalysts are: tris-(dialkylamino)-s-hexahydrotriazines, in particular tris-(N,N-dimethylamino)-s-hexahydrotriazine, tetraalkylammonium salts such as N,N,N-trimethyl-N-(2-hydroxypropyl)formate, N,N,N-trimethyl-N-(2-hydroxypropyl)-2-ethylhexanoate, tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, alkali hydroxides such as sodium hydroxide, alkali alkoxides such as sodium methylate and potassium isopropylate, and alkali or alkaline earth salts of fatty acids having 1 to 20 C atoms and optionally pendant OH groups.

[0065] Tertiary amines, tin compounds, alkali and alkaline earth carboxylates, quaternary ammonium salts, s-hexahydrotriazines and tris-(dialkylaminomethyl)phenols are preferably used.

[0066] Preferably, 0.001 to 5% by weight, in particular 0.002 to 2% by weight of catalyst or catalyst combination, based on the total weight of the starting mixture, are used.

[0067] The polyurethane preferably comprises at least one component containing an active hydrogen atom capable of forming a hydrophilic group, preferably from 1 to 15 wt.%, in particular from 3 to 10 wt.%, and particularly preferably from 4 to 7 wt.%. "Active hydrogen atom" means that the hydrogen atom in question of the component is unstable in such a way that it can easily enter into a chemical reaction, e.g., a substitution reaction, with other compounds, so that a hydrophilic group can be formed. This component enables the polyurethane to be efficiently dispersed in water. The hydrophilic group is selected, in particular, from: -COO - , -SO3 - , -NR3 + and -(CH2CH2O) n -The at least one component containing an active hydrogen atom is particularly preferably selected from dimethylolpropionic acid (DMPA), dimethylolbutyric acid (DMBA), polyethylene oxide, bis(hydroxyethyl)amines and sodium 3-bis(hydroxyethyl)aminopropanesulfonate.

[0068] For the purpose of dispersion, the polyurethane dispersion may alternatively or additionally contain at least one surfactant.

[0069] Particularly suitable surfactants that also act as foam stabilizers are Stokal® STA (ammonium stearate) and Stokal® SR (succinamate) from the Bozzetto Group.

[0070] However, other surfactants are also suitable, which can in particular be selected from the group consisting of ether sulfates, fatty alcohol sulfates, sarcosinates, organic amine oxides, sulfonates, betaines, amides of organic acids, sulfosuccinates, sulfonic acids, alkanolamides, ethoxylated fatty alcohols, sorbinates and combinations thereof.

[0071] As a further optional component, the starting mixture for producing the polyurethane layer can contain a thickener. For this purpose, Borchi® Gel 0625, for example, can be used. Polyetherurethane solutions such as Ortegol® PV301 from Evonik Industries are also suitable as thickeners. A thickener ensures stability during drying.

[0072] The starting mixture may contain further additives such as stabilizers and / or light stabilizers. Solvents may also be added as further additives. Suitable solvents for the production of polyurethane materials include ketones, e.g., acetone; carboxylic acid alkyl esters such as methyl acetate; alkyl carbonates; or amides such as DMF; and / or additional liquid flame retardants such as alkyl phosphates such as triethyl phosphate or tributyl phosphate; halogenated alkyl phosphates such as tris-(2-chloropropyl) phosphate or tris-(1,3-dichloropropyl) phosphate; aryl phosphates such as diphenyl cresyl phosphate; and phosphonates such as diethyl ethanephosphonate. Mixtures of the solvents mentioned can also be used.

[0073] Further optional additives are cell regulators of the type known per se such as paraffins and / or fatty alcohols and / or dimethylpolysiloxanes, flame retardants, pigments and / or dyes, stabilizers against aging and weathering influences, plasticizers, fungistatic and bacteriostatic substances, fillers such as barium sulfate, bentonite, kaolin, glass powder, glass beads, glass fibers, calcium carbonate, diatomaceous earth, quartz sand, fluoropolymers, thermoplastics, microspheres, expandable graphite, carbon black or whiting or combinations thereof.

[0074] As an alternative to the two variants described so far, the polyurethane layer can also be formed from solution.

[0075] The process for forming the polyurethane layer, preferably one made from a dispersion, preferably comprises forming using an anilox roller. In the simplest case, the dosage of the application weight can be adjusted via the engraving of the anilox roller, which is filled, for example, in a scoop trough. Particularly preferably, the process comprises a further step in which the mass to be formed passes through a smoothing doctor blade arranged downstream of the anilox roller, which is preferably a chamber doctor blade and particularly preferably a pressure chamber doctor blade. With the latter, the application weight can be adjusted particularly precisely via the pressure of the coating fluid as a further coating parameter. The coating speed is preferably 50 to 150 m / min.

[0076] The polyurethane layer preferably completely covers both the polymer layer with which it forms the interface (A), as well as the further layer connected to it, which follows in the adhesive tape structure accordingly; otherwise, there would be a risk of tears during machine passage due to exposed adhesive sections. On the other hand, there is also the requirement that the polyurethane layer is not too thick, because splicing adhesive tapes in the context described here are generally preferably made as thin as possible to avoid obstructing the flying reel splice process due to thick spots. The polyurethane layer preferably has an application weight of 1.5 to 50 g / m, regardless of its type of formation. 2 , more preferably from 1.7 to 20 g / m 2 , especially from 1.9 to 10 g / m 2 , most preferably from 2.0 to 5 g / m 2 , on.

[0077] In a preferred embodiment of the invention, one of the polymer layers (K31) and (K32), in particular the polymer layer (K32), is a polyester layer, in particular a polyester film, very particularly preferably a biaxially stretched polyethylene terephthalate film, and the other of the polymer layers (K31) and (K32), in particular the polymer layer (K31), is a polyurethane layer or a polyamide layer, more preferably a polyurethane layer, in particular an extruded polyurethane layer based on thermoplastic polyurethane or a dispersion-based polyurethane layer, in each case as described above. The composite of the polymer layers (K31) and (K32) is particularly preferably obtained by applying a polyurethane dispersion to a polyethylene terephthalate film and subsequently drying the dispersion.

[0078] The polyester layer, in particular the biaxially oriented polyethylene terephthalate film, preferably has a thickness of 9 to 100 µm, more preferably 23 to 75 µm, in particular 30 to 50 µm. If the polyester layer is too thick, it is too stiff and forms a thick spot that can lead to tearing during machine passage. On the other hand, if it is too thin, there is a risk of spotty connections between the adhesive layers K1 and K2, for example, due to adhesive residues that can occur at the cutting edges from the conversion of the adhesive tape.

[0079] In one embodiment of the invention, the splittable layer (K3) comprises a laminating adhesive layer (K33) on the side of the polymer layer (K31) facing the adhesive layer (K1) and a further polymer layer (K34) on the side thereof facing the adhesive layer (K1). As has been shown, the reliability of the splitting process can be further optimized in this way. In particular, the probability of occasional blockage of the splitting process, as can be caused, for example, by the adhesive residues from the conversion at the edges of the splittable layer described above, is further minimized. Particularly preferably, the splittable layer (K3) comprises a laminating adhesive layer (K33) on the surface of the polymer layer (K31) facing the adhesive layer (K1) and a polymer layer (K34) on the surface thereof facing the adhesive layer (K1).Most preferably, the fissile layer (K3) consists of the layer sequence. Polymer layer (K34) Laminating adhesive layer (K33) Polymer layer (K31) Polymer layer (K32).

[0080] The adhesive tape according to the invention preferably comprises the layer sequence: Adhesive layer (K1) Polymer layer (K34) Laminating adhesive layer (K33) Polymer layer (K31) Polymer layer (K32) Adhesive layer (K2).

[0081] In a further development of the embodiment with layers (K33) and (K34), polymer layers (K34) and (K32) have an overhang on both sides transverse to the web direction of the adhesive tape (K) relative to the laminating adhesive layer (K33) and the polymer layer (K31). Preferably, the composite of the laminating adhesive layer (K33) and the polymer layer (K31) is flush. The overhang is preferably 0.5 to 3.5 mm on each side, more preferably 0.7 to 3.3 mm on each side, in particular 0.9 to 3.1 mm on each side. As has been shown, such an overhang reduces the required splitting force and improves the reliability of the intended splitting at interface A.

[0082] For the laminating adhesive of layer (K33), all solvent-based, solvent-free, and aqueous adhesives known per se in the prior art with different polymer bases, e.g., polyurethane, polyester, polyethylene, or ethylene-vinyl acetate, are suitable. The laminating adhesive is preferably a polyurethane-based adhesive. "Polyurethane-based" here means that a polyurethane or a combination of several polyurethanes forms the main component of the polymer composition of this adhesive, i.e., accounts for the largest proportion of the polymer composition.

[0083] Solvent-free polyurethane adhesives can be available as one- or two-component systems. Further differences can arise from the structure of the polyurethane and the type of crosslinking. The following polymers are often preferred: 1-component system: low molecular weight prepolymers, NCO-terminated, moisture-curing; 2-component system: prepolymers with NCO end groups + polyols.

[0084] Aromatic isocyanates are frequently used, although aliphatic isocyanates are occasionally used, especially when UV stability is required. Generally, aromatic isocyanates achieve better adhesion and faster curing.

[0085] Polyether polyurethanes generally have higher temperature stability than polyester polyurethanes. However, the polyol component often consists of a mixture of polyester and polyether polyols. Tri- and higher functionalized polyols are also frequently used to generate additional crosslinking effects, which in turn often results in higher temperature stability.

[0086] In one embodiment, the laminating adhesive of the layer (K33) is based on a polyurethane dispersion.

[0087] It may be advantageous to allow a composite made of polymer layers (K31) and (K34) using the laminating adhesive layer (K33) to rest for several hours or even days to achieve full bond strength. It may also be advantageous to subject the surfaces to be bonded to a physical pretreatment, such as a corona pretreatment, prior to bonding.

[0088] The polymer layer (K34) preferably comprises at least 80% by weight, more preferably at least 90% by weight, in particular at least 95% by weight, and most preferably at least 98% by weight, each based on the total weight of the layer in question, of one or more polymers selected from the group consisting of polyesters, polyolefins, and polyamides, more preferably polyesters and polyolefins, in particular polyesters. More preferably, the polymer layer (K34) is a film selected from the group consisting of polyester films, polyolefin films, and polyamide films, particularly preferably polyester films and polyolefin films, in particular polyester films.The polymer layer (K34) is particularly preferably a film selected from the group consisting of biaxially stretched polyester films, biaxially stretched polyolefin films and biaxially stretched polyamide films, in particular from biaxially stretched polyester films and biaxially stretched polyolefin films, very particularly preferably from biaxially stretched polyester films.

[0089] The polymer layer (K34) is particularly advantageously selected from the group consisting of monoaxially oriented polypropylene films, biaxially oriented polypropylene films, biaxially stretched polyamide films, biaxially stretched polyethylene naphthalate films, biaxially stretched polyethylene terephthalate films and biaxially stretched polyethylene furanoate films. In particular, the polymer layer (K34) is selected from the group consisting of biaxially stretched polyethylene naphthalate films, biaxially stretched polyethylene terephthalate films and biaxially stretched polyethylene furanoate films. Very particularly preferably, the polymer layer (K34) is a biaxially stretched polyethylene terephthalate film. Additionally preferably, the material of the polymer layer (K34) is more than 50 wt. %, more preferably more than 75 wt. %, in particular more than 85 wt.-% and most preferably completely recycled, i.e. it has already undergone at least one use-recycling cycle before being processed into the polymer layer (K34).

[0090] In a further particular embodiment of the invention, the cleavable layer (K3) comprises a coextrudate of an ethylene-vinyl acetate copolymer film and a mixture of polystyrene and a styrene-butadiene copolymer. The vinyl acetate content in the ethylene-vinyl acetate copolymer is preferably at most 20 wt. %, more preferably at most 15 wt. %, in particular at most 12 wt. %, for example at most 10 wt. The vinyl acetate content in the ethylene-vinyl acetate copolymer is particularly preferably 6 to 12 wt. %.

[0091] In the mixture of polystyrene and a styrene-butadiene copolymer, the polystyrene is preferably a high-impact polystyrene, and the weight fraction of the styrene-butadiene copolymer is preferably a maximum of 25 wt%.

[0092] As has been shown, under these conditions, the release forces that are particularly suitable for the intended use of the adhesive tape are achieved.

[0093] The adhesive layers (K1) and (K2) are preferably pressure-sensitive adhesive layers. In accordance with expert understanding, a pressure-sensitive adhesive is an adhesive that possesses pressure-sensitive adhesive properties, i.e., the ability to form a permanent bond to a substrate even under relatively light pressure. Such pressure-sensitive adhesive tapes are usually permanently tacky even at room temperature, meaning they exhibit a certain viscosity and initial tack, allowing them to wet the surface of a substrate even under light pressure. The tackiness of a pressure-sensitive adhesive tape results from the fact that a pressure-sensitive adhesive is used as the adhesive.Without wishing to be bound by this theory, it is often assumed that a pressure-sensitive adhesive can be viewed as an extremely viscous liquid with an elastic component, which consequently exhibits characteristic viscoelastic properties that lead to the permanent inherent tack and pressure-sensitive adhesive capacity described above. It is assumed that with corresponding pressure-sensitive adhesives, mechanical deformation leads to both viscous flow processes and the build-up of elastic restoring forces. The partial viscous flow serves to achieve adhesion, while the partial elastic restoring forces are particularly necessary to achieve cohesion. The relationships between rheology and pressure-sensitive tack are known in the art and are described, for example, in "Satas, Handbook of Pressure Sensitive Adhesives Technology", Third Edition, (1999), pages 153 to 203.To characterise the degree of elastic and viscous components, the storage modulus (G') and the loss modulus (G") are usually used, which can be determined by means of dynamic mechanical analysis (DMA), for example using a rheometer, as disclosed, for example, in WO 2015 / 189323 A1. In the context of the present invention, an adhesive is preferably understood to be pressure-sensitively adhesive and thus as a pressure-sensitive adhesive if, at a temperature of 23 °C in the deformation frequency range of 1 to 10 rad / sec, G' and G'' are each at least partly in the range of 10. 3 up to 10 7 Pa lie.

[0094] Preferably, the adhesive layers (K1) and (K2) are based independently of one another on one or more polymers selected from the group consisting of poly(meth)acrylates, natural rubber, synthetic rubbers, and silicones. The adhesive layers (K1) and (K2) can therefore also be based on mixtures of the aforementioned polymers.

[0095] Particularly in the case where an adhesive tape according to the invention is intended for processing flat paper webs, the adhesive layers (K1) and (K2) are preferably repulpable, in particular repulpable according to the TAPPI UM 213 measurement method (TAPPI Useful Methods 213, issued 2012). Such adhesives can be largely or completely incorporated into the pulp during paper recycling, i.e., into the paper or fiber pulp dissolved or suspended in water. However, this may require prior, e.g., mechanical, separation of the splittable layer (K3), whose materials are often not repulpable.

[0096] In the simplest case, an adhesive tape according to the invention can consist of the components listed so far, i.e., the splittable layer (K3) and the two adhesive layers (K1) and (K2). In this case, the splittable layer (K3) also serves as the carrier for the two adhesive layers (K1) and (K2).

[0097] One of the adhesive layers (K1) and (K2) in the adhesive tape according to the invention is preferably provided for applying the adhesive tape to the second layer of the new roll of flat web material. In this respect, one of the adhesive layers (K1) and (K2) is preferably an outer layer of the adhesive tape (K), in other words, a layer that completes the structure of the adhesive tape (K) on one side toward the outside. In the above, simplest embodiment, the other adhesive layer is preferably provided as a contact adhesive for the expiring roll of flat web material to be replaced and thus, in this embodiment, is also an outer layer of the adhesive tape (K).

[0098] In a further embodiment, in addition to the components listed so far, the adhesive tape comprises a carrier layer (T), which can also be referred to as the “main carrier”. The carrier layer (T) preferably comprises a material selected from the group consisting of paper, metals, and polymers. More preferably, the carrier layer (T) comprises a material selected from the group consisting of paper, polyethylene terephthalate, polyethylene, polypropylene, polyvinyl chloride, and aluminum. In particular, the carrier layer (T) comprises a material selected from the list consisting of paper, polyethylene terephthalate films, polyethylene films, polypropylene films, polyvinyl chloride films, and a laminate of aluminum and paper. The carrier layer (T) is preferably printed in black or white, colored black or white, or comprises a metal foil, in particular an aluminum foil. This advantageously allows optical or inductive detection of the adhesive tape.

[0099] Preferably, on one side of the carrier layer (T), a structure with the sequence adhesive layer (K1) - splittable layer (K3) - adhesive layer (K2) or adhesive layer (K2) - splittable layer (K3) - adhesive layer (K1), which can also be referred to as a "splitting strip", is arranged; and on the other side of the carrier layer (T), a further adhesive layer (K4), preferably a pressure-sensitive adhesive layer, is arranged. In practice, such an adhesive tape would preferably be used such that the top layer of the new flat web material roll is applied to the adhesive layer (K4) and the adhesive layer (K1) or (K2) rests on the subsequent layer of the new roll. The material of the old flat web material roll to be replaced also adheres to the adhesive layer (K4) during the roll change. The adhesive layer (K1) or (K2) establishes the contact between the carrier layer and the splittable layer (K3).

[0100] Preferably, in the adhesive tape according to the invention, the respective outer pressure-sensitive adhesives—in the simplest form, thus (K1) and (K2), in the above embodiment (K4) on the one hand and (K1) or (K2) on the other—have a high initial tack (also referred to as "tack"). This is advantageous for (K1) and (K2) because it mitigates the effects of a possibly careless adhesive tape application or a rougher substrate surface, and ensures reliable bonding to the second layer of the new flat web material roll. Therefore, a good tack is helpful here to achieve a broad processing window.

[0101] If (K1) or (K2) or – according to the above embodiment – ​​(K4) is the second outer adhesive of the adhesive tape according to the invention, these adhesives act as contact adhesives to the old material web during flying roll splices. A high tack is advantageous here because the contact between the old and new material webs is only brief, and therefore the material of the old web must immediately adhere sufficiently strongly to the adhesive tape to ensure further processing in accordance with the process.

[0102] If the adhesive tape according to the invention comprises an adhesive layer (K4) and thus (K1) or (K2) establishes the bond between the carrier layer (T) and the splittable layer (K3), this adhesive, which is arranged within the adhesive tape structure (and not externally), is characterized in particular by high shear strength and low cold flow. This is particularly advantageous for achieving high aging stability and thus avoiding subsequent blocking of the splitting system.

[0103] Preferably, more preferably, the two adhesive layers arranged on the outside each comprise adhesives based on one or more synthetic rubbers independently of one another.

[0104] If, in the structure of the adhesive tape according to the invention, one of the adhesive layers (K1) and (K2) functions as an internal adhesive layer, this preferably comprises, and more preferably is, a (meth)acrylate adhesive, in particular a pure acrylate adhesive formed from solution or a resin-blended acrylate adhesive formed from solution.

[0105] Pure acrylic adhesives consist of one or more homopolymers and / or copolymers, each of which is based exclusively on acrylate and / or methacrylate monomers. Such adhesives are also referred to as "100% systems." Acrylic adhesives can also be based on copolymers of acrylic monomers, i.e., acrylates and / or methacrylates, and non-acrylic monomers, as well as on blends that each comprise at least two representatives from the group consisting of pure polyacrylates, copolymers of acrylic monomers and non-acrylic monomers, and (co)polymers composed exclusively of non-acrylic monomers.

[0106] In a further development of the embodiment of the adhesive tape according to the invention with a carrier layer (T), the splittable layer (K3) with the two adhesive layers (K1) and (K2) is applied in the form of a strip, this strip extending parallel to and at a distance (Ab) from an edge region (LK3) of the adhesive tape (K) extending in the longitudinal direction (IK) of the adhesive tape (K). The distance (Ab) formed as an indentation can be up to 10 mm, preferably it is 0.5 to 5 mm, more preferably 1 to 3 mm. This indentation also reduces the required splitting force and contributes to the reliability of the intended splitting at the interface A.

[0107] By selecting the width of the split strip—i.e., the layer sequence "adhesive layer (K1) - splittable layer (K3) - adhesive layer (K2)" or "adhesive layer (K2) - splittable layer (K3) - adhesive layer (K1)"—the splitting energy required to completely split the predetermined breaking surface can be adjusted independently of the width of the main carrier (T). This is not possible for systems in which the predetermined breaking surface extends across the entire width (bK) of the adhesive tape (K).

[0108] To overcome the splitting strength at the leading edge, an increased maximum force is required to split the splitting system or the splittable layer (K3) (initial splitting force). Furthermore, a force at a lower level is required to split across the entire width of the splitting strip (further splitting force). The initial splitting force must be set high enough to prevent the adhesive tape from opening prematurely due to the centrifugal and aerodynamic forces acting on the moving web during acceleration. On the other hand, the further splitting force must be set low enough that completely splitting the splitting system does not lead to web breaks. A key quality factor is the constant further splitting force of the splitting strip, which must be set at a defined level within narrow limits.

[0109] In addition to determining the specific materials of the polymer layers (K31) and (K32) and their configuration, the splitting forces of the adhesive tape according to the invention can also be adjusted, for example, by physically pretreating one of the two or both adjacent surfaces of the polymer layers (K31) and (K32) that form the interface (A). The physical pretreatment comprises, in particular, corona treatment or plasma application. Alternatively or additionally, the splitting forces can also be adjusted by mechanically treating one of the two or both adjacent surfaces of the polymer layers (K31) and (K32). For example, the splitting forces can be increased by roughening the polyethylene terephthalate film that is preferably present in the splittable layer (K3).

[0110] A further subject matter of the invention is a flat web material (RB) which is wound onto a roll (R) and is characterized in that an adhesive tape (K) according to the invention is applied to the flat web material (RB).

[0111] A further object of the invention is the use of an adhesive tape (K) according to the invention as an adhesive for joining two flat web materials (RB) wound on rolls (R), (B) within a flying roll change.

[0112] As already explained, the flat web material is preferably selected from paper, nonwovens, woven fabrics, and films, in particular polymer films. As has been shown, the invention brings advantages for the use of the various materials. When processing paper, for example, the invention prevents fibers from the splittable adhesive tape used from accumulating in coating or printing units, where they could lead to functional impairments of the machines in the medium term. When processing films, if the films are used for separator films or electrodes in batteries, fiber residues from the splittable adhesive tape can form defects and promote the occurrence of short circuits. This risk is significantly reduced by the invention and is generally completely avoided.Films for medical applications or for use with food, when produced using an adhesive tape according to the invention, are characterized by even higher purity, i.e. lower contamination with foreign substances.

[0113] Description of the figures: The invention is explained in more detail below with reference to the figures. Fig. 1 a schematic representation of an adhesive tape according to the invention; Fig. 2 a schematic representation of an adhesive tape according to the invention in the embodiment with a carrier layer, wherein the splittable layer is applied as a strip; Fig. 3a-d a schematic representation of a flying roll change using an adhesive tape according to the invention; Fig. 4 a schematic representation of an adhesive tape according to the invention in the embodiment with the laminating adhesive layer (K33) and the polymer layer (K34); Fig. 5a-b a schematic representation of a flying reel change using an adhesive tape according to the invention in the Fig. 4 shown embodiment.

[0114] Fig. Figure 1 schematically shows the structure of an adhesive tape (K) according to the invention in its simplest form, comprising the adhesive layers (K1) and (K2) located on top and bottom, and the splittable layer (K3) arranged between them, which is formed from the polymer layers (K31) and (K32). The interface (A) between the polymer layers (K31) and (K32) forms the predetermined breaking surface for splitting the adhesive tape (K) during a flying roll change.

[0115] Fig. Figure 2 shows schematically the structure of an adhesive tape (K) according to the invention in the embodiment with the carrier layer (T) and the adhesive layer (K4) lying on its upper side. The adhesive layer (K4) is preferably located, as in Fig. 2, over its entire surface on the main carrier (T); however, it can also be applied only partially. The composite consisting of the carrier layer (T) and the adhesive layer (K4) has on its long side the edge region (LK3) extending in the longitudinal direction (IK) of the adhesive tape (K), to which the split strip, i.e. the composite consisting of the adhesive layer (K1), the splittable layer (K3) with the polymer layers (K31) and (K32) and the predetermined breaking surface (A) running between them, as well as the adhesive layer (K2), runs parallel and indented by the distance (Ab). The total width (bK) of the adhesive tape (K) is determined by the composite consisting of the carrier layer (T) and the adhesive layer (K4).

[0116] In the Fig. 3a - 3d show an example of a flying roll change between two rolls (R) and (B) of a flat web material (RB).

[0117] Fig. Figure 3a shows that first the new roll (R) of the flat web material (RB) is prepared by applying the flat web section forming the uppermost winding to the flat web section forming the second winding using an adhesive tape (K) according to the invention, which is shown in Fig. 2, is fixed. The flat track section forming the uppermost winding is applied to the adhesive layer (K4) of the adhesive tape (K), and the adhesive layer (K2) of the adhesive tape (K) is bonded to the flat track section forming the second winding. As can be seen, a part of the adhesive layer (K4) is left open, which now, as Fig. 3b shows, is available for bonding with the last part of the material (RB) of the running-off old flat web material roll (B).

[0118] Fig. Figure 3b further shows how the thus prepared roll (R) is placed next to an almost completely unwound and thus to be replaced old roll (B) and accelerated to approximately the same circumferential speed as the old roll. The roll (B) is then pressed against the new roll (R) by means of a pressure cylinder (Z), so that, as Fig. 3c shows how the material of the old roll is bonded to the exposed area of ​​the adhesive layer (K4) and how the splice, i.e. the connection between the flat web materials (RB) of the two rolls (R) and (B), is created.

[0119] Simultaneously with or immediately after the splice is made, the adhesive tape (K) opens at the interface between the polymer layers (K31) and (K32), as shown in Fig. 3c and in particular in Fig. 3d. This allows the flat web material (RB) of the new roll (R), which is now connected to the flat web material (RB) of the unwinding roll (B), to be threaded directly into the ongoing processing, and the new roll (R) can be unwound without interrupting the process.

[0120] Fig. Figure 4 schematically shows the structure of an adhesive tape (K) according to the invention with adhesive layers (K1) and (K2) located on top and bottom and the splittable layer (K3) arranged between them, which layer is formed here from the polymer layers (K31) and (K32) as well as a laminating adhesive layer (K33) arranged on the surface of the polymer layer (K31) facing the adhesive layer (K1) and a polymer layer (K34) arranged on the surface of the polymer layer (K31) facing the adhesive layer (K1). The interface (A) between the polymer layers (K31) and (K32) forms the predetermined breaking surface for splitting the adhesive tape (K) during flying roll changes.

[0121] Fig. Figure 5a shows a section of the process of a flying roll change between two rolls (R) and (B) of a flat web material (RB) using a device extended by the laminating adhesive layer (K33) and the polymer layer (K34), otherwise similar to the illustration in Fig. 2 corresponding adhesive tape (K) according to the invention. The flat web section forming the uppermost winding was applied to a portion of the adhesive layer (K4) of the adhesive tape (K), and the adhesive layer (K2) of the adhesive tape (K) was bonded to the flat web section forming the second winding. The remaining portion of the adhesive layer (K4) creates the bond with the last portion of the material (RB) of the expiring old flat web material roll (B). In this way, the splice, i.e., the connection between the flat web materials (RB) of the two rolls (R) and (B), is created.

[0122] As in Fig. As can be further seen in Figure 5a, the adhesive tape (K) opens between the polymer layer (K31) - which is bonded to the subsequent layers of the adhesive tape (K) by means of the layer sequence "adhesive layer (K1) / polymer layer (K34) / laminating adhesive layer (K33)" - and the polymer layer (K32). This allows the flat web material (RB) of the new roll (R), now bonded to the flat web material (RB) of the unwinding roll (B), to be threaded directly into the ongoing processing, and the new roll (R) can be unwound without interrupting the process.

[0123] Fig.Figure 5b shows the process just described at an advanced stage. The splitting of the adhesive tape (K) between the polymer layers (K31) and (K32) is now clearly visible. Connected to the top layer of the new roll (R) of flat web material (RB) and the last part of the unwinding roll (B), one part of the split adhesive tape (K) remains, consisting of the polymer layer (K31), laminating adhesive layer (K33), polymer layer (K34), adhesive layer (K1), carrier layer (T), and adhesive layer (K4), while the other part, here consisting of the polymer layer (K32) and adhesive layer (K2), remains on the second layer of the new flat web material roll (R). Measurement methodsMethod 1 - Determination of the splitting force

[0124] To determine the splitting force (initial force to initiate the splitting process of the predetermined breaking point), tab samples of the adhesive tape according to the invention are produced in DIN A4 size.

[0125] One edge of the rag sample is then trimmed to create a smooth cut edge. A tear-resistant paper is placed on one adhesive layer of the sample to be tested; the exposed adhesive surface is covered with siliconized paper. The tear-resistant paper is lightly coated with a finger to prevent air pockets. The hand roller is then quickly rolled over the composite twice to achieve perfect bond strength. The bond must be created so that the end of the tear-resistant paper protrudes beyond the adhesive tape body at the smooth edge. Using a steel ruler, strips are cut out from the smooth edge of the composite. These strips are 15 mm wide (parallel to the smooth edge) and approximately 20 cm long (at right angles to the smooth edge). The protruding end of the paper is located at one end. This protruding end of the paper will then serve as a handle.

[0126] A sample produced as described above is clamped into a tensile testing machine, whereby the siliconized paper on the front adhesive layer is peeled off and the sample, with its now exposed surface, is firmly bonded horizontally to a carrier clamped in the tensile machine by means of a clamping device. Care must be taken to ensure that the predetermined breaking point has not yet split before the measurement begins. The paper (grip tab) applied to the back adhesive layer is then pulled at a speed of 300 m / min such that the sample splits at an angle of 90° at the predetermined breaking point. The initial force is recorded (this corresponds to the maximum of the force-displacement curve), and the measured value is standardized to a 1 cm sample width based on the actual sample width. The average of three measurements is given (in N / cm). Method 2 - Determination of the splitting force

[0127] To determine the further splitting force, test strips corresponding to method 1 are prepared with the only difference that tear-resistant papers with protruding ends are applied to both the surface of the first and the surface of the second adhesive (on the lower surface instead of the siliconized paper).

[0128] To measure the further splitting force, the prepared sample is first split by hand along one of its narrow edges. The sample is then clamped into the clamping devices of a tensile testing machine at both grips of the covering paper and held in place with the fingers so that it is perpendicular to both tensile directions and the splitting process continues at the initial gap when the tensile testing machine is started up. Both grips are pulled equally so that the sample splits further at a speed of 300 mm / min at an angle of 180°. The splitting occurs at the predetermined breaking point. The force required to continue the splitting process is specified, standardized to a 1 cm sample width (in cN / cm).

[0129] Test conditions for methods 1 and 2: temperature 23 ± 1 °C; 50 ± 5% relative humidity; air pressure 1013 ± 5 mbar. Experiment description

[0130] A laboratory splice machine (LSM) was used, which can be used to conduct application tests on flying splices of flat web materials. The LSM consists of two rubberized rollers, each with a diameter of 600 mm, which can be moved together to a predefined position. The rubber coating has a hardness of 50 Shore A, and that of the lower roller has a hardness of 80 Shore A.

[0131] Before the test, a roller position corresponding to a line pressure of 200 N / m was calibrated with the machine stationary.

[0132] Both rollers were wrapped with biaxially oriented polypropylene film. The splicing tape to be tested was applied to the lower roller. The following tapes were used: a) tesa Easysplice® 51918 FilmLine Black S (commercially available splicing tape with paper-based splitting mechanism b) a splicing tape manufactured as follows: The structure of splicing tape a) was reproduced, with the difference that the paper-based splitting mechanism was replaced by a PET / PU splitting mechanism. For this purpose, a PU varnish with an application weight of 2 g / m 2 applied to a 36 µm PET film. The two outer adhesives of splicing tape a) were each coated onto process liner and laminated to both sides of the previously prepared PET / PU splitting system (identical application weight as for tape a)). The resulting structure was applied to the underside of the carrier layer, which had already been coated with adhesive on the top side, according to tape a). The resulting tape was cut to the same dimensions as tape a).

[0133] Both rollers were accelerated in synchronization to a surface speed of 1,000 m / min. Both adhesive tapes maintained their position on the substrate of the lower roller during acceleration. After reaching the target speed, the rollers were moved together for one revolution to the previously calibrated position.

[0134] Both adhesive tapes bonded to the substrate of the upper roller and were split as desired, so that the lower adhesive tape portion remained on the film material of the lower roller and the upper tape portion was transferred to the film material of the upper roller. After both rollers came to a standstill, both adhesive tape portions were visually inspected.

[0135] In the case of adhesive tape a), a clearly perceptible fiber tear was observed.

[0136] For adhesive tape b), no material tearing was detected. Reference symbol A interface From distance B old role bK Total width of the adhesive tape K Adhesive tape K1 adhesive layer K2 adhesive layer K3 fissile layer K31 polymer layer K32 polymer layer K33 laminating adhesive layer K34 polymer layer K4 adhesive layer IK Longitudinal direction of the adhesive tape LK3 edge area T Carrier layer R new role RB flat track material Z pressure cylinder QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 1 022 245 A2

[0005] EP 1 076 026 A2

[0006] EP 1 640 301 A1

[0007] EP 3 124 565 A1

[0008] EP 3 460 017 A1

[0009] WO 2015 / 189323 A1

[0093] Cited non-patent literature

[0000] Satas, Handbook of Pressure Sensitive Adhesives Technology“, Third Edition, (1999), pages 153 to 203

[0093] Measuring method TAPPI UM 213 (TAPPI Useful Methods 213, issued 2012

[0095]

Claims

[1] Adhesive tape (K) for the flying roll change of flat web material (RB) wound on rolls (R, B), wherein the adhesive tape a splittable layer (K3) comprising two polymer layers (K31, K32) lying directly on top of one another, which form a predetermined breaking surface at their interface (A) for splitting the adhesive tape (K) over its entire surface; a first adhesive layer (K1) which is arranged on the side of the polymer layer (K31) facing away from the interface (A); and a second adhesive layer (K2) which is arranged on the side of the polymer layer (K32) facing away from the interface (A). [2] Adhesive tape (K) according to claim 1, characterized by that one of the polymer layers (K31) and (K32) comprises at least 80% by weight, based on the total weight of the layer, of one or more polymers selected from the group consisting of polyesters, polyolefins and polyamides. [3] Adhesive tape (K) according to one of claims 1 and 2, characterized by that one of the polymer layers (K31) and (K32) is selected from the group consisting of biaxially stretched polyester films, mono- or biaxially stretched polyolefin films and biaxially stretched polyamide films. [4] Adhesive tape (K) according to one of the preceding claims, characterized by that one of the polymer layers (K31) and (K32) is a biaxially stretched polyethylene terephthalate film. [5] Adhesive tape (K) according to one of claims 2 to 4, characterized by that this polymer layer is the polymer layer (K32). [6] Adhesive tape (K) according to one of the preceding claims, characterized by that the polymer layer (K31) is a polyurethane layer. [7] Adhesive tape (K) according to one of the preceding claims, characterized bythat the splittable layer (K3) comprises a laminating adhesive layer (K33) on the side of the polymer layer (K31) facing the adhesive layer (K1) and a polymer layer (K34) on the side thereof facing the adhesive layer (K1). [8] Adhesive tape (K) according to one of the preceding claims, characterized by that the adhesive layers (K1) and (K2) are pressure-sensitive adhesive layers. [9] Adhesive tape (K) according to one of claims 7 and 8, characterized by that the polymer layers (K34) and (K32) have an overhang on both sides transverse to the web direction of the adhesive tape (K) towards the laminating adhesive layer (K33) and the polymer layer (K31). [10] Adhesive tape (K) according to one of the preceding claims, characterized by that the adhesive tape comprises a carrier layer (T) which is printed in black or white or coloured in black or white or comprises a metal foil. [11] Flat web material (RB) wound on a roll (R, B), characterized bythat an adhesive tape (K) according to one of claims 1 to 10 is applied to the flat web material (RB). [12] Use of an adhesive tape (K) according to one of claims 1 to 10 as an adhesive for joining two flat web materials (RB) wound on rolls within a flying roll change.