Adhesive based on polyvinylaromatic-polydiene-block copolymers with improved hot shear strength

Abstract

The invention relates to an adhesive mass based on polyvinylaromatic compound-polydiene block copolymers, which comprises at least one type of cationically curable reactive resin, the improvement of the hot shear strength being achieved by the curing of the reactive resin. The invention further relates to an adhesive tape comprising at least one layer of this adhesive mass and to a method for its manufacture.

Description

[0001] This invention relates to pressure-sensitive adhesives (pressure-sensitive adhesive substances, pressure-sensitive adhesive compositions) based on polyvinyl aromatic compound-polydiene block copolymers, wherein the pressure-sensitive adhesive comprises at least one cationic curable reactive resin, and the curing of the cationic curable reactive resin achieves an increase in thermal shear strength. The invention further relates to tapes comprising at least one layer of such pressure-sensitive adhesive, and to processes for preparing them.

[0002] Pressure-sensitive adhesives based on polyvinyl aromatic compounds-polydiene block copolymers are common pressure-sensitive adhesives used in self-adhesive products. They are advantageously used for bonding a wide range of materials, including non-polar materials. They exhibit high adhesive strength (peel adhesion) at normal application temperatures, while also demonstrating good cohesive strength. Pressure-sensitive adhesives based on polyvinyl aromatic compounds-polydiene block copolymers can be processed from melt and solution in a solvent-free manner.

[0003] For many applications, such as in the automotive industry, there is a persistent need for improved thermal shear strength in pressure-sensitive adhesives based on commercially available polyvinyl aromatic compounds-polydiene block copolymers. This is related to the specific physical crosslinking principles in these formulations. As a result of the targeted utilization of the incompatibility and separation between different types of blocks, domains (regions) rich in polyvinyl aromatic compounds are formed, which act as crosslinking points in the temperature range below their glass transition temperature. If the glass transition temperature is reached, the cohesive strength decreases. There is a persistent need for formulations for self-adhesive tapes that exhibit an excellent balance between high thermal shear strength and good peel adhesion.

[0004] Various methods have been described regarding how to achieve improvements in the thermal shear strength of formulations based on polyvinyl aromatic compounds-polydiene block copolymers.

[0005] For example, the thermal shear strength of pressure-sensitive adhesive formulations can be improved by influencing the molar mass (DE 10 2012212 879 A1) and structure (US 5,372,870 A) of the polyvinyl aromatic compound-polydiene block copolymer.

[0006] This includes the use of adjuvants with high softening temperatures that are miscible with domains rich in polyvinyl aromatic compounds. WO00 / 24840 A1 claims polyphenylene oxide resins for this purpose. Eastman Chemical describes highly softening aromatic compound resins in its technical bulletin (“Kristalex and Endex Hydrocarbon Resins for Improved PSA Performance”, Eastman Chemical Company, document TT-85, August 2007).

[0007] Radiation-chemical crosslinking of formulations based on polyvinyl aromatic compounds—polydiene—is also described, both without and with an additional crosslinking agent (WO00 / 22062 A1) and with an additional crosslinking agent (DE 10 2008 056 980 A1). The crosslinking agent is conventionally used in small amounts, less than 10% by weight, such as that claimed, for example, in DE 10 2015 109 659 A1 (0.05 to 5% by weight of crosslinking aid). The crosslinking here occurs via a free radical mechanism and results in covalent (chemical) bonding of elastomer molecules.

[0008] Block copolymers in combination with epoxy resins are known from descriptions of reactive coatings. Upon curing, epoxy-based reactive coatings typically exhibit high hardness but also brittleness. Such adhesives and coating materials can be impact-modified by adding thermoplastic elastomers, as illustrated, for example, in DE 10 2009 026 548 A1. The main component in such systems, also known as castings or potting materials, is conventionally an epoxy (Thomas, S., Sinturel, C., & Thomas, R. (ed.). (2014). Micro and nanostructured epoxy / rubber blends. John Wiley & Sons.).

[0009] Formulations containing polyvinyl aromatic compound block copolymers and epoxides are known from DE 10 2012 202377 A1 and DE 10 2015 212 058 A1. The formulations claimed herein are based on polystyrene-polyisobutylene block copolymers, particularly for use in water vapor barrier adhesives. The epoxide is described as a reactive diluent that results in very good laminationability of the tape prior to curing, and that it contributes to their final technical application performance properties through curing. Curing is carried out here by radiation chemistry or thermal means. No polydiene-based adhesives are disclosed in these documents. No formulations based on polyvinyl aromatic compound-polydiene block copolymers are mentioned.

[0010] JP 2000 / 290 619 A1 describes formulations comprising an elastomer (100 parts by weight), a cationic curable material such as an epoxide (10 to 200 parts by weight), and a photocationic polymerization initiator. Specifically, a combination is given as 100 parts by weight of SBS (Tufprene A and / or Epofriend A1010) with 120 parts by weight of glycidyl ether Epicoat 828. Tufprene A and Epofriend A1010 have a polystyrene (PS) fraction of 40%. The disclosure states that the tape is a reactive tape, curing immediately before adhesion to the target component. Curing of such formulations, independent of subsequent immediate lamination, may result in layers that are no longer pressure-sensitive adhesives. The disclosure does not teach compositions for self-adhesive tapes that exhibit an excellent balance between high thermal shear strength and good peel adhesion.

[0011] JP 2018 / 02 950A1 claims an adhesive based on a styrene block copolymer for use in heat-sealing films, comprising an epoxy resin, a curing agent, and 1-cyanoethyl-2-ethyl-4-methylimidazolium as a curing accelerator for the epoxy resin.

[0012] WO 1999 / 009101 A1 and US 7,429,419 B2 disclose adhesives having epoxy resin and epoxy group-functionalized block copolymers.

[0013] DE 10 2018 202 545 A1 claims specific formulations based particularly on polystyrene-polyisobutylene block copolymers, which also contain epoxides. Advantageously, however, these epoxides can be thermo-cured and / or radiochemically cured prior to lamination. Formulations based on polyvinyl aromatic compounds-polydiene block copolymers are not described.

[0014] The objective remains to provide formulations for self-adhesive tapes that exhibit an excellent balance between high thermal shear strength, more specifically a SAFT temperature of at least 150°C according to Test I, and good peel adhesion of at least 4 N / cm according to Test II.

[0015] Although the proposed formulations comprising a combination of block copolymers and epoxy resins are available from various sources, the requirement for formulations used in self-adhesive tapes—an excellent balance between high thermal shear strength and good peel adhesion—cannot be achieved through arbitrary selection of the block copolymers and epoxy resins. More surprisingly, the proposed requirement can be achieved through formulations (i.e., pressure-sensitive adhesives) containing the following base formulations:

[0016] (i) 25 to 45% by weight, preferably 30 to 40% by weight, of at least one elastomer component comprising at least one polyvinyl aromatic compound-polydiene block copolymer,

[0017] The polyvinyl aromatic compound-polydiene block copolymer wherein the polyvinyl aromatic compound-polydiene block copolymer has at least partially (proportionally, in a specific order, anteilig) ABA, (AB) n (AB) n X or (ABA) n The X structure, in which

[0018] - Block A is a polymer formed independently of each other by polymerization of at least one vinyl aromatic compound;

[0019] - Block B is a polymer formed independently of each other by polymerization of a conjugated diene having 4 to 18 carbon atoms, or a derivative of such a polymer partially hydrogenated in a polydiene block;

[0020] -X represents residues of the coupling agent or initiator; and

[0021] -n is an integer ≥2.

[0022] The at least one polyvinyl aromatic compound-polydiene block copolymer wherein the peak molar mass of the tested IVa is at least 160,000 g / mol, preferably at least 200,000 g / mol.

[0023] The fraction of the A block in the at least one polyvinyl aromatic compound-polydiene block copolymer is at least 8% by weight and at most 25% by weight, and

[0024] Optionally, up to 25% by weight of a diblock copolymer AB comprising blocks A and B as defined above may be present, based on the total elastomer composition.

[0025] (ii) 33 to 55% by weight, preferably 40 to 50% by weight, of at least one tackifier resin component having at least one tackifier resin, wherein said at least one tackifier resin has a softening temperature of ≥80°C, preferably ≥100°C, and typically up to 130°C (ring and ball method, test VII), and

[0026] (iii) 13 to 30% by weight, preferably 16 to 25% by weight, of at least one reactive resin component, comprising at least 70% by weight of a resin having a strength of 17.82 to 17.50 MPa. 1 / 2 Preferably 17.80 to 17.70 MPa 1 / 2 The dispersive component δ of the Hansen parameter D At least one reactive resin based on cyclic ether,

[0027] In their respective cases, based on the base formulation, the sum of the elastomer component and the reactive resin component is at least 38% by weight and at most 68% by weight.

[0028] In the basic formulation of the present invention, the total weight fraction of the elastomer component, the tackifier resin component, and the reactive resin component is 100% by weight. Furthermore, the sum of the elastomer component and the reactive resin component is at least 38% by weight and at most 68% by weight, preferably at least 50% by weight and at most 60% by weight, respectively, based on the basic formulation of the present invention. Preferably, if the basic formulation contains a solvent, the solvent is ignored when reporting the weight fraction.

[0029] The formulation also contains an initiator for cationic curing (curing component) of the reactive resin component, and optional additional components such as plasticizers and / or additives. Therefore, the total pressure-sensitive adhesive formulation consists of a base formulation, a curing component, and optional additional components. Within the scope of this specification, the terms "pressure-sensitive adhesive (pressure-sensitive adhesive substance, pressure-sensitive adhesive composition)" and "self-adhesive composition" are used synonymously.

[0030] Furthermore, the present invention relates to a cured pressure-sensitive adhesive that can be obtained by curing the pressure-sensitive adhesive as described above.

[0031] The present invention also relates to tapes comprising at least one layer of pressure-sensitive adhesive as described above or a layer of cured pressure-sensitive adhesive. If the tape includes a carrier, the pressure-sensitive adhesive is preferably applied over its entire area. However, the invention also covers embodiments in which only a portion of the pressure-sensitive adhesive is applied.

[0032] Furthermore, the present invention also relates to a method for preparing such a tape, wherein a solvent-based (solvent-containing) adhesive is coated and dried, and thermal curing of the adhesive is performed or initiated during the drying operation.

[0033] Preferred embodiments of the subject matter are found in the dependent claims.

[0034] Pressure-sensitive adhesives:

[0035] The composition of the pressure-sensitive adhesive of the present invention is described in more detail below.

[0036] (a) Basic formulation - (i) Elastomer component:

[0037] The elastomer component comprises at least one polyvinyl aromatic compound-polydiene block copolymer. The polyvinyl aromatic compound-polydiene block copolymer is preferably a polystyrene-polydiene block copolymer, and particularly polystyrene-polybutadiene, polystyrene-polyisoprene, or polystyrene-polyfarnes block copolymers, for example, more particularly polystyrene-polybutadiene block copolymers.

[0038] The polyvinyl aromatic compound-polydiene block copolymer has at least a proportion of ABA and (AB). n (AB) n X or (ABA) n The X structure, in which

[0039] - Block A is a polymer formed independently of each other by polymerization of at least one vinyl aromatic compound;

[0040] - Block B is a polymer formed independently of each other by polymerization of a conjugated diene having 4 to 18 carbon atoms, or a derivative of such a polymer partially hydrogenated in a polydiene block;

[0041] -X represents residues of the coupling agent or initiator; and

[0042] -n is an integer ≥2.

[0043] In this specification, triblock copolymers are typically understood to mean block copolymers having an ABA or (AB)2X structure. Similarly, in this specification, radial block copolymers are typically understood to mean block copolymers having an (AB)2X structure. n X or (ABA) n Block copolymers with an X structure, where n is an integer ≥ 3. Preferred radial block copolymers here have a structure (AB). n X, where n is an integer ≥ 3. In this specification, the terms “radial,” “star,” and “multi-arm” are used synonymously.

[0044] Therefore, suitable block copolymers (vinyl aromatic block copolymers) contain one or more rubbery blocks B (soft blocks). At least one block copolymer has two or more glassy blocks A (hard blocks). The elastomer component preferably contains at least one triblock copolymer ABA or (AB)2X and / or at least one radial (AB) n X-block copolymers, where n is an integer ≥3. Particularly preferred herein are at least one triblock copolymer ABA or (AB)2X and at least one radial (AB)2X copolymer. n A mixture of X block copolymers. In the radial direction (AB) nIn the X block copolymer, n is preferably 3 or 4. Accordingly, the at least one block copolymer preferably has an ABA, (AB)2X, (AB)3X, or (AB)4X structure, wherein A, B, and X conform to the above definitions. In an advantageous embodiment, all block copolymers have an ABA, (AB)2X, (AB)3X, or (AB)4X structure, wherein A, B, and X conform to the above definitions. However, it is also advantageous if the elastomer component consists of a mixture of block copolymers having an ABA, (AB)2X, (AB)3X, or (AB)4X structure and a small amount of block copolymers with different structures, such as diblock copolymer AB.

[0045] Segment A is also referred to as a "hard segment" in the context of this invention. Correspondingly, segment B is also referred to as a "soft segment" or "elastomeric segment". According to the invention, this reflects the segment selection according to the invention corresponding to their glass transition temperatures (at least 25°C, preferably at least 50°C, and more particularly at least 75°C for segment A, and at most 0°C, more particularly at most -50°C, for example at most -75°C, as determined by DSC, Test III in their respective cases).

[0046] The diblock copolymer AB can also be used in combination with the block copolymer. However, it has been found that excessively high fractions of diblock copolymer result in unsatisfactory hot shear strength. Therefore, the fraction of diblock copolymer in the elastomer component is at most 25% by weight, very preferably at most 20% by weight. It can also be done without any diblock copolymer. For example, a high diblock fraction resulting from the addition of diblock-rich vinyl aromatic compound block copolymers surprisingly leads not only to a deterioration in hot shear strength but also to a reduction in peel adhesion.

[0047] The at least one block copolymer typically comprises, on the one hand, polymer blocks (A blocks) mainly formed of vinyl aromatic compounds, preferably polystyrene, and on the other hand, blocks (B blocks) mainly formed of polymerizations or copolymers of 1,3-dienes such as butadiene and isoprene. The product may also be partially hydrogenated in the diene blocks. Particularly suitable block copolymers for partially hydrogenated derivatives are those in which, in particular, any vinyl group (i.e., repeating units present in an unsaturated form in the side chain, such as 1,2-polybutadiene, 1,2-polyisoprene, or 3,4-polyisoprene) has been hydrogenated (i.e., ultimately present in a hydrogenated form). An example of such partially hydrogenated block copolymers is polystyrene-polybutene-butadiene block copolymer (SBBS).

[0048] The block copolymer of the pressure-sensitive adhesive preferably has polystyrene end blocks.

[0049] The vinyl aromatic compound used to construct block A preferably comprises styrene, α-methylstyrene, and / or other styrene derivatives. Block A may be in the form of a homopolymer or copolymer. Block A is more preferably polystyrene.

[0050] Instead of the preferred polystyrene blocks, compounds with a glass transition temperature greater than 75°C, based on other aromatic compounds (preferably C8 to C4), can also be used. 12 Polymer blocks of homopolymers and copolymers of aromatic compounds, such as aromatic compound blocks containing α-methylstyrene, are vinyl aromatic compounds. Additionally, identical or different A blocks may also exist.

[0051] The fraction of A block in at least one block copolymer of the elastomer component is at least 8% by weight and at most 25% by weight.

[0052] Preferred conjugated dienes as monomers of the soft block B are particularly selected from butadiene, isoprene, farnesene, ethylbutadiene, phenylbutadiene, pentadiene, pentene, hexadiene, ethylhexadiene, and dimethylbutadiene, as well as any desired mixtures of these monomers. Block B may also be in the form of a homopolymer or copolymer.

[0053] The conjugated diene that serves as the monomer of the soft block B is more preferably selected from butadiene and isoprene. For example, the soft block B is polyisoprene, polybutadiene, or a partially hydrogenated derivative of one of these polymers, such as, in particular, polybutene-butadiene; or a polymer of a mixture of butadiene and isoprene. Very preferably, the block B is polybutadiene.

[0054] The at least one polyvinyl aromatic compound-polydiene block copolymer has a peak molar mass of at least 160,000 g / mol according to the test IVa, preferably—and especially when selecting a polystyrene-polybutadiene block copolymer—at least 200,000 g / mol.

[0055] (a) Basic formulation - (ii) Tackifier resin component:

[0056] Based on the general understanding of those skilled in the art, "tackifier resin" is understood to be an oligomer or polymer resin that improves the adhesion (tackiness, inherent tack) of a pressure-sensitive adhesive compared to a pressure-sensitive adhesive that does not contain a tackifier resin but is otherwise identical.

[0057] The molar mass of the tackifier resin (according to test IVb) is conventionally between 500 and 5000 g / mol.

[0058] The tackifying resins used in this invention are advantageously those that are compatible with the soft blocks of the polyvinyl aromatic compound-polydiene block copolymer of the elastomer component.

[0059] Therefore, a tackifier resin having a DAP (diacetone alcohol cloud point, test V) of at least 90% by weight, more preferably at least 95% by weight (based on the tackifier resin component) is selected. This DAP is greater than +5°C, preferably greater than +10°C and less than +65°C (if polyisoprene block copolymer is present in the elastomer portion), and preferably less than +50°C (if polyisoprene block copolymer is not present in the elastomer portion). Also preferably, the MMAP (mixed methylcyclohexane aniline point, test VI) of the at least one tackifier resin is at least +50°C, more preferably at least +60°C, and at most +100°C (if polyisoprene block copolymer is present in the elastomer portion), and more preferably at most +90°C (if polyisoprene block copolymer is not present in the elastomer portion). The at least one tackifier resin has a softening temperature (ring and ball method, test VII) of ≥80°C, preferably ≥100°C, and more preferably up to 130°C.

[0060] It has been found that non-polar hydrocarbon resins, such as hydrogenated and non-hydrogenated polymers of dicyclopentadiene, non-hydrogenated or partially, selectively, or fully hydrogenated hydrocarbon resins based on C5, C5 / C9, or C9 monomer streams, and polyterpene resins based on α-pinene and / or β-pinene and / or δ-limonene, can be advantageously used as tackifier resins for pressure-sensitive adhesives. The aforementioned tackifier resins can be used alone or in mixtures. Hydrocarbon resins or polyterpene resins are preferably used at a level of at least 90% by weight. Hydrogenated or non-hydrogenated tackifier resins also containing oxygen can optionally be used in the adhesive at a maximum fraction of up to 10%, based on the tackifier resin component.

[0061] More preferably, the tackifier resin is only a hydrocarbon resin or a terpene resin or a mixture thereof.

[0062] (a) Basic formulation - (iii) Reactive resin components :

[0063] The objective of this invention is achieved through a combination of specific polyvinyl aromatic compounds-polydiene block copolymers and specific reactive resins. Unbound by theory, a possible explanation for the fact that only specific representatives of the two groups of raw materials result in favorable adhesive properties involves the selective compatibility of the reactive resin with the domain of the polyvinyl aromatic compounds, wherein, in their cured form, they stabilize the cross-linked state formed due to microphase separation even at elevated temperatures.

[0064] Accordingly, the reactive resin component contains at least 70% by weight of a resin with a strength of 17.82 to 17.50 MPa. 1 / 2 Preferably 17.80 to 17.70 MPa 1 / 2 The dispersive component δ of the Hansen parameterD At least one reactive resin based on a cyclic ether. Here, the dispersive component δ of the Hansen parameter of the reactive resin is... D The dispersive component δ of the Hansen parameter of the polyvinyl aromatic compound of the at least one polyvinyl aromatic compound-polydiene block copolymer. D The preferred difference is at most 2 MPa 1 / 2 .

[0065] The solubility parameter δ in the three-dimensional Hansen solubility space is defined as follows (Eric A. Grulke, “Polymer Handbook”, 3rd edition, Chapter VII, pp. 519-559):

[0066] δ=(δ D 2 +δ P 2 +δ H 2 ) 1 / 2 ,in

[0067] -δ D It describes the attractive force caused by the spontaneous aggregation of particles and the resulting dipoles induced in adjacent particles (see London-Dispersion).

[0068] -δ P The Debye attraction involving permanent dipoles, and

[0069] -δ H It describes specific interactions, such as hydrogen bonds or acid-base interactions.

[0070] In this invention, calculations related to the Hansen parameters are performed using the HSPiP software (http: / / hansen-solubility.com). This software employs a group contribution method based on the functional units of molecules.

[0071] Reactive resins based on cyclic ethers are preferably used for thermosetting and / or radiation-chemical curing, i.e., by photoinitiator. The reactive resin is cationically curable. Reactive resins based on cyclic ethers are preferably epoxides, i.e., compounds carrying at least one ethylene oxide group, or oxetanes. Epoxides are particularly preferred. The cyclic ether is typically aliphatic or alicyclic in nature, with alicyclic epoxides being particularly preferred. "The cyclic ether is alicyclic in nature" in this invention typically means that the cyclic ether is partially fused with an alicyclic group. The reactive resins that can be used can be monofunctional, difunctional, trifunctional, tetrafunctional, or up to multifunctional or higher, where functionality refers to the cyclic ether group. Diepoxides are particularly preferred. Without wishing to impose arbitrary limitations, preferred examples are 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexane carboxylate (EEC) and its derivatives. The reactive resin can be used in its monomeric or dimer, trimer, etc., up to its oligomeric form. EEC is preferred.

[0072] Studies show that the solubility of (3,4-epoxycyclohexyl)methyl 3,4-epoxycyclohexylcarboxylate is particularly advantageous for embedding into the styrene domain of synthetic rubber. Table 1 shows the Hansen parameters for polystyrene and various diepoxides, as well as the difference δ value Δ between the Hansen parameters of the diepoxides and polystyrene.

[0073]

[0074] Table 1: Hansen parameters and associated δ values ​​for polystyrene and various diepoxides.

[0075] The crosslinking of alicyclic epoxides in the styrene domain decreases with increasing distance from the desired (3,4-epoxycyclohexyl)methyl 3,4-epoxycyclohexylcarboxylate. This implies a decrease in the cohesive strength of the sample.

[0076] Regarding the stated purpose, aromatic epoxy resins are surprisingly unsuitable for incorporation into styrene domains, and a third phase forms in the SBC epoxy blends. This can be concluded from the AFM images and is manifested in the severe turbidity of the samples. The result regarding blend formation is particularly surprising, as it is expected that aromatic epoxides would have particularly good compatibility with aromatic styrene domains and should therefore have a positive effect in the sense of the stated purpose. However, this is not demonstrated.

[0077] It is also possible to mix reactive resins with each other or with other co-reactive compounds such as alcohols (monofunctional or polyfunctional) or vinyl ethers (monofunctional or polyfunctional).

[0078] (b) Initiator for cationic curing of the at least one reactive resin:

[0079] The pressure-sensitive adhesive of the present invention further comprises an initiator, also known as an activator, without which the curing of the reactive resin under economically viable conditions would be impossible. The initiator is typically present in an amount of 0.1 to 5% by weight, based on the amount of the reactive resin component.

[0080] The initiator is typically selected from thermally activated initiators for initiating cationic curing, photoinitiators for initiating cationic curing (i.e., radiation-activated initiators, such as, in particular, UV initiators), and mixtures thereof. These types of initiators are known to those skilled in the art. Here, the fraction of the thermally activated initiator relative to the reactive resin component is preferably at least 0.2% by weight and at most 4.0% by weight, and more preferably at least 0.3% by weight and at most 2.5% by weight. Here, the fraction of the radiation-activated initiator relative to the reactive resin is preferably at least 0.2% by weight and at most 5% by weight, and more preferably at least 0.5% by weight and at most 4% by weight.

[0081] Selecting a suitable thermal initiator (if used) for the cationic curing of reactive resins presents a particular challenge. The temperature required to activate the thermal initiator should be within the range where the adhesive can cure in a sufficiently short time. Therefore, it should be consistent with the manufacturing process used for self-adhesive tapes.

[0082] This can be achieved, in particular, by solvent-based coatings of adhesive formulations. The heat-activated initiator used for cationic curing should advantageously cause the reactive resin to cure within the temperature range of the drying operation of the solvent-based coating. In this case, the activation temperature should be at most 150°C, preferably, practically at most 100°C.

[0083] A series of thermally activated initiators for the cationic curing of, for example, epoxides have been described in the past. In this context, the term "curing catalyst" is often used instead of "initiator." However, many common curing systems used for epoxides are typically unsuitable for the purposes of this invention. These include BF3-amine complexes, acid anhydrides, imidazoles, amines, DICY, dialkylphenyl acylthioonium salts, triphenylbenzyl phosphonium salts, and amine-terminated phenylsulfonium acids. For many of these curing systems, the activation and / or curing properties are not adequately suited to the manufacturing methods used for self-adhesive tapes. For example, the pot life may be insufficient or the required curing time or technical application performance properties may not be achieved.

[0084] Thermally activated initiators suitable for the cationic curing of cyclic ethers in the sense of this invention are, in particular, pyridinium salts such as N-benzylpyridinium salt or benzylpyridinium salt, ammonium salts such as anilineium salts (e.g., N-anisylmethyl-N,N-dimethylanilineium salt), thioonium salts such as cyclohexyldiphenylthioonium salt, dicyclopentenyldipropylthioonium salt, p-methoxybenzyltetrahydrothiophenium salt, cyclopentyldiphenylthioonium salt, or especially thiolanium salts, and trifluoromethanesulfonate metal salts such as calcium, zinc, aluminum, or rare earth or lanthanide trifluoromethanesulfonates or mixtures thereof. N-benzylpyridinium salts and benzylpyridinium salts are particularly advantageous, wherein the aromatic compound may be substituted, for example, with alkyl, alkoxy, halogen, or cyano groups. (J. Polym. Sci. A,) 1995 ,33, page 505 and thereafter, US 2014 / 0367670A1, US 5,242,715, J.Polym.Sci.B, 2001 ,39, page 2397 and thereafter, EP 393893A1, Macromolecules, 1990 ,23,431 and thereafter, Macromolecules, 1991 ,24,2689,Macromol.Chem.Phys., 2001Page 2554 and thereafter, WO 2013 / 156509A and JP 2014 / 062057 A1 mention the corresponding compounds that may be preferred for use in the sense of the present invention. Among commercially available initiator systems, examples of compounds that can be used very advantageously include San-Aid SI 60L, San-Aid SI 80L, San-Aid SI 100L, San-Aid SI 35 110L, San-Aid B2A, San-Aid B3A, and San-Aid B3 from Sanshin; Opton CP-66 and Opton CP-77 from Adeka; UVC 511, UVC 522, UVC 531, UVC 542, and UVC 560 from Synlab GmbH; and K-Pure TAG 2678, K-Pure CXC 1612, K-Pure CXC 1613, and K-Pure CXC 1614 from King Industries. Lanthanide trifluoromethanesulfonates, such as samarium(III) trifluoromethanesulfonate, ytterbium(III) trifluoromethanesulfonate, erbium(III) trifluoromethanesulfonate, dysprosium(III) trifluoromethanesulfonate, and lanthanum(III) trifluoromethanesulfonate, are also readily available from Sigma Aldrich, and are available from Alfa Aesar. Suitable anions for use as initiators include hexafluoroantimonate, hexafluorophosphate, hexafluoroarsinate, tetrafluoroborate, tetra(pentafluorophenyl)borate, and trifluoromethanesulfonate. Anions according to JP 2012-056915 A1 and EP 393893 A1 are also available. Those skilled in the art will recognize other systems that can also be used in this invention.

[0085] The heat-activated initiator for cationic curing is used either uncombined or as a combination of two or more heat-activated initiators. Advantageous for the purposes of this invention is the heat-activated initiator having an activation temperature of at least 25°C and up to 200°C, preferably at least 50°C and up to 150°C, at which the cationic curing of the reactive resin can be initiated. The activation time can be 15 seconds or longer and 15 minutes or shorter, although shorter or longer activation times are not excluded. The curing operation can also continue after the activation time.

[0086] In an advantageous embodiment of the invention, the curing reaction of the tape is substantially complete at the lamination time point, in terms of the achievable conversion rate of the curing reaction. However, the curing operation may not be completely complete at the lamination time point, also in terms of the achievable conversion rate of the curing reaction.

[0087] As a photoinitiator, a radiation-activated initiator, a compound that absorbs UV light below 350 nm and allows cation curing can be used, for example, with the photoinitiator particularly selected from thionium, iodonium, and metallocene-based photoinitiators and mixtures thereof. Thionium-based photoinitiators are particularly preferred. Examples of thionium-based cations can be found in the observations in US 6,908,722 B1 (especially columns 10 to 21). Examples of anions used as counterions to the above-mentioned cations include tetrafluoroborate, tetraphenylborate, hexafluorophosphate, perchlorate, tetrachloroferrate, hexafluoroarsenate, hexafluoroantimonate, pentafluorohydroxyantimonate, hexachloroantimonate, tetra-pentafluorophenylborate, tetra(pentafluoromethylphenyl)borate, di-(trifluoromethylsulfonyl)amide, and tri(trifluoromethylsulfonyl)methyl compounds. Specifically for iodonium-based initiators, other conceivable anions are chloride, bromide, or iodide, although preferred initiators are substantially free of chlorine and bromine. More specifically, usable systems include: thionium salts (see, for example, US 4,231,951 A, US 4,256,828 A, US 4,058,401 A, US 4,138,255 A and US2010 / 063221). A1) For example, triphenylthionium hexafluoroarsenate, triphenylthionium hexafluoroborate, triphenylthionium tetrafluoroborate, triphenylthionium tetra(pentafluorobenzyl)borate, methyl diphenylthionium tetrafluoroborate, methyl diphenylthionium tetra(pentafluorobenzyl)borate, dimethyl phenylthionium hexafluorophosphate, triphenylthionium hexafluorophosphate, triphenylthionium hexafluoroantimonate, diphenylnaphthionium hexafluoroarsenate, trimethylmethylthionium hexafluorophosphate, anisyl diphenylthionium hexafluoroantimonate, 4-butoxyphenyl diphenylthionium tetrafluoroborate, 4-butoxyphenyl diphenylthionium tetra(pentafluorobenzyl)borate, 4-chlorophenyl diphenylthionium hexafluoroantimonate, tri(4-phenoxyphenyl)thionium hexafluorophosphate, di-(4-) (-ethoxyphenyl)methylthionium hexafluoroarsenate, 4-acetylphenyldiphenylthionium tetrafluoroborate, 4-acetylphenyldiphenylthionium tetra(pentafluorobenzyl)borate, tris(4-thiomethoxyphenyl)thionium hexafluorophosphate, di(methoxysulfonylphenyl)methylthionium hexafluoroantimonate, di(methoxynaphthyl)methylthionium tetrafluoroborate, di(methoxynaphthyl)methylthionium tetra(pentafluorobenzyl)borate, di(methoxycarbonylphenyl)methylthionium hexafluorophosphate, (4-octyloxyphenyl)diphenylthionium tetra(3,5-bis(trifluoromethyl)phenyl)borate, tris[4-(4-acetylphenyl)thionium]thionium tetra(pentafluorophenyl)borate, tris(dodecylphenyl) ...5-Bis-trifluoromethylphenyl)borate, 4-acetaminophenyl diphenylthionium tetrafluoroborate, 4-acetaminophenyl diphenylthionium tetra(pentafluorobenzyl)borate, dimethylnaphthium hexafluorophosphate, trifluoromethyl diphenylthionium tetrafluoroborate, trifluoromethyl diphenylthionium tetra(pentafluorobenzyl)borate, phenylmethyl benzylthionium hexafluorophosphate, 5-methylthianthrenium hexafluorophosphate, 1-O-phenyl 9,9-Dimethylthioxanthenium hexafluorophosphate, 1-O-phenyl-9-oxothioxanthenium tetrafluoroborate, 1-O-phenyl-9-oxothioxanthenium tetra(pentafluorobenzyl)borate, 5-methyl-10-oxothiathanthium tetrafluoroborate, 5-methyl-10-oxothiathanthium tetra(pentafluorobenzyl)borate, and 5-methyl-10,10-dioxothiathanthium hexafluorophosphate, iodothium salts (see, for example, US 3,729,313 A, US 3,741,769 A, US 4,250,053 A, US 4,394,403 A and US2010 / 063221) A1) Examples include diphenyliodonium tetrafluoroborate, di(4-methylphenyl)iodonium tetrafluoroborate, phenyl-4-methylphenyliodonium tetrafluoroborate, di(4-chlorophenyl)iodonium hexafluorophosphate, dinaphthyliodonium tetrafluoroborate, di(4-trifluoromethylphenyl)iodonium tetrafluoroborate, diphenyliodonium hexafluorophosphate, di(4-methylphenyl)iodonium hexafluorophosphate, diphenyliodonium hexafluoroarsenate, di(4-phenoxyphenyl)iodonium tetrafluoroborate, phenyl-2-thienyliodonium hexafluorophosphate, 3,5-dimethylpyrazolyl-4-phenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, 2,2'-diphenyliodonium tetrafluoroborate, di(2,4-Dichlorophenyl)iodonium hexafluorophosphate, bis(4-bromophenyl)iodonium hexafluorophosphate, bis(4-methoxyphenyl)iodonium hexafluorophosphate, bis(3-carboxyphenyl)iodonium hexafluorophosphate, bis(3-methoxycarbonylphenyl)iodonium hexafluorophosphate, bis(3-methoxysulfonylphenyl)iodonium hexafluorophosphate, bis(4-acetamidophenyl)iodonium hexafluorophosphate, bis(2-benzothiophene)iodonium hexafluorophosphate, diaryliodonium trifluoromethanesulfonylmethyl compounds such as diphenyliodonium hexafluoroantimonate, diaryliodonium tetra(pentafluorophenyl)borate such as diphenyl [4-(2-hydroxy-n-tetramethylsilyloxy)phenyl]phenyliodonium tetra(pentafluorophenyl)borate, [4-(2-hydroxy-n-tetramethylsilyloxy)phenyl]phenyliodonium hexafluoroantimonate, [4-(2-hydroxy-n-tetramethylsilyloxy)phenyl]phenyliodonium trifluorosulfonate, [4-(2-hydroxy-n-tetramethylsilyloxy)phenyl]phenyliodonium hexafluorophosphate, [4-(2-hydroxy-n-tetramethylsilyloxy)phenyl]phenyliodonium tetra(pentafluorophenyl)borate, bis(4-tert-butylphenyl)iodonium Hexafluoroantimonate, bis(4-tert-butylphenyl)iodonium hexafluorophosphate, bis(4-tert-butylphenyl)iodonium trifluorosulfonate, bis(4-tert-butylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium hexafluorophosphate, bis(dodecylphenyl)iodonium trifluoromethanesulfonate, di(dodecylphenyl)iodonium hexafluoroantimonate, di(dodecylphenyl)iodonium trifluoromethanesulfonate, diphenyliodonium hydrogen sulfate, 4,4'-dichlorodiphenyliodonium hydrogen sulfate, 4, 4'-Dibromodiphenyliodonium hydrogen sulfate, 3,3'-dinitrodiphenyliodonium hydrogen sulfate, 4,4'-dimethyldiphenyliodonium hydrogen sulfate, 4,4'-bissucciniminodiphenyliodonium hydrogen sulfate, 3-nitrodiphenyliodonium hydrogen sulfate, 4,4'-dimethoxydiphenyliodonium hydrogen sulfate, bis(dodecylphenyl)iodonium tetra(pentafluorophenyl)borate, (4-octyloxyphenyl)phenyliodonium tetra(3,5-bis-trifluoromethylphenyl)borate and (tolylcumyl)iodonium tetra(pentafluorophenyl)borate, and ferrocene salts (see, for example, EP 0 542 716 B1) such as n5-(2,4-cyclopentadien-1-yl)-[(1,2,3,4,5,6,9)(1-methylethyl)benzene]iron.

[0088] Examples of commercially available photoinitiators include Cyracure UVI-6990, Cyracure UVI-6992, Cyracure UVI-6974, and Cyracure UVI-6976 from Union Carbide; Optomer SP-55, Optomer SP-150, Optomer SP-151, Optomer SP-170, and Optomer SP-172 from Adeka; San-Aid SI-45L, San-Aid SI-60L, San-Aid SI-SOL, San-Aid Sl-1 OOL, San-Aid SI-110L, San-Aid SI-150L, ​​and San-Aid SI-180L from Sanshin Chemical; SarCat CD-1010, SarCat CD-1011, and SarCat CD-1012 from Sartomer; and Degacure from Degussa. K185, Rhodorsil Photoinitiator 2074 from Rhodia, CI-2481, CI-2624, CI-2639, CI-2064, CI-2734, CI-2855, CI-2823 and CI-2758 from Nippon Soda, Omnicat 320, Omnicat 430, Omnicat 432, Omnicat 440, Omnicat 445, Omnicat 550, Omnicat 550BL and Omnicat 650 from IGM Resins, Daicat II from Daicel, UVAC 1591 from Daicel-Cytec, FFC 509 from 3M,from Midori Kagaku's BBl-102, BBl-103, BBl-105, BBl-106, BBl-109, BBl-110, BBl-201, BBI, 301, Bl-105, DPl- 105, DPl-106, DPl-109, DPI-201, DTS-102, DTS-103, DTS-105, NDS-103, NDS-105, NDS-155, NDS-159 , NDS-165, TPS-102, TPS-103, TPS-105, TPS-106, TPS-109, TPS-1000, MDS-103, MDS-105, MDS-109, M DS-205, MPl-103, MPl-105, MPl-106, MPl-109, DS-100, DS-101, MBZ-101, MBZ-201, MBZ-301, NAl-20 P Al-1001, Pl-105, Pl-106, Pl-109, PYR-100, Sl-101, Sl-105, Sl-106 and Sl-109, Kayacure PCI-204, Kayacure PCI-205, Kayacure PCI-615, Kayacure PCI-625, Kayarad from Nippon Kayaku 220 and Kayarad 620, PCI-061T, PCI-062T, PCI-020T, PCI-022T, TS-01 and TS-91 from Sanwa Chemical, Deuteron UV 1240 from Deuteron, Tego Photocompound 1465N from Evonik, UV 9380C-D1 from GE Bayer Silicones, and FX 512 from Cytec.The UV catalysts used include Siliconease UV Cata 211 from Bluestar Silicones, and Irgacure 250, Irgacure 261, Irgacure 270, Irgacure PAG 103, Irgacure PAG 121, Irgacure PAG 203, Irgacure PAG 290, Irgacure CGI 725, Irgacure CGI 1380, Irgacure CGI 1907, and Irgacure GSID 26-1 from BASF, as well as UV 387C, UV 1240, UV 1242, UV 1244, UV1707, UV 1708, and UV 2257 from Synlab. Other systems that can be used similarly in this invention will be known to those skilled in the art.

[0089] Photoinitiators can be used uncombined or as a combination of two or more photoinitiators and / or thermal initiators. Advantageous photoinitiators are those with absorption less than 350 nm and advantageously greater than 250 nm. Initiators absorbing above 350 nm in the violet range, for example, can also be used. Thionium-based photoinitiators are particularly preferred because they have advantageous UV absorption properties. In this case, the activation time is typically greater than 1 second and typically less than 5 minutes, although shorter or longer activation times are not excluded. The curing process can also continue after the activation time. In an advantageous embodiment of the invention, the curing reaction of the tape is substantially completed at the lamination time point, in terms of the conversion rate achievable in the curing reaction. The curing process may not be completely finished at the lamination time point, in terms of the conversion rate achievable in the curing reaction. If a solvent-based formulation is applied, the photoinitiator is advantageously activated after the drying operation.

[0090] (c) Optional further ingredients:

[0091] When selecting alternative materials, care should be taken to ensure that no component or chemically structured group so strongly influences the curing process of the reactive resin components that the desired performance of the formulation cannot be guaranteed after curing. For example, (strong) nucleophiles or substances with basic reactivity should be avoided.

[0092] Optionally, at least one plasticizer may be used, for example. These are more particularly plasticizing resins, and very preferably polyterpene resins or hydrocarbon resins that are liquid at room temperature, preferably in fractions of 1 to 5% by weight, based on the total weight of the total pressure-sensitive adhesive.

[0093] The following additives can be selected for typical use:

[0094] • The main antioxidant, such as a sterically hindered phenol, is preferably present in a fraction of 0.2 to 1% by weight, based on the total weight of the total pressure-sensitive adhesive;

[0095] • Co-antioxidants, such as phosphites, thioesters or thioethers, preferably in fractions of 0.2 to 1% by weight, based on the total weight of the total pressure-sensitive adhesive;

[0096] • Process stabilizers, such as C radical scavengers, preferably in fractions of 0.2 to 1% by weight, based on the total weight of the total pressure-sensitive adhesive;

[0097] • Light stabilizers, such as UV absorbers or sterically hindered amines, are preferably present in a fraction of 0.2 to 1% by weight, based on the total weight of the total pressure-sensitive adhesive;

[0098] • Processing aids, preferably in fractions of 0.2 to 1% by weight, based on the total weight of the total pressure-sensitive adhesive, and

[0099] Optionally preferred are other polymers with elastomeric properties; the corresponding elastomers particularly include those based on pure hydrocarbons, such as unsaturated polydienes like naturally or synthetically produced polyisoprene or polybutadiene, chemically substantially saturated elastomers such as saturated ethylene-propylene copolymers, α-olefin copolymers, polyisobutylene, butyl rubber, and ethylene-propylene rubber, and chemically functionalized hydrocarbons such as halogenated, acrylate-containing, and allyl or vinyl ether-containing polyolefins, preferably in fractions of 0.2 to 10% by weight, based on the total weight of the total pressure-sensitive adhesive.

[0100] In one embodiment of the invention, the pressure-sensitive adhesive further comprises additional additives; non-limiting examples include crystalline or amorphous oxides, hydroxides, carbonates, nitrides, halides, carbides, or mixed oxides / hydroxides / halides of aluminum, silicon, zirconium, titanium, tin, zinc, iron, or alkali / alkaline earth metals. These are essentially alumina, such as aluminum oxides, boehmite, gibbsite, diaspore, etc. Layered silicates are particularly suitable, examples being bentonite, montmorillonite, hydrotalcite, lithium montmorillonite, kaolinite, boehmite, mica, vermiculite, or mixtures thereof. Additionally, carbon black or other modified carbons, such as carbon nanotubes, may also be used. Silica may also be present, advantageously precipitated silica, or silica surface-modified with dimethyldichlorosilane.

[0101] Adhesives can also be colored with dyes or pigments. Adhesives can be white, black, or colored.

[0102] Pressure-sensitive adhesives used for pressure-sensitive adhesive layers can be in a foamable or foamable form. For this purpose, a foaming agent can be provided in the formulation. Expanded or expandable microspheres are particularly preferred as foaming agents. However, chemical foaming agents can also be used alone or in combination with other foaming agents. Pressure-sensitive adhesives can also be physically foamed or have been physically foamed, i.e., by incorporating gaseous or supercritical fluid substances or compositions.

[0103] In the case of foaming, foaming is specifically achieved by introducing microspheres and subsequently expanding them.

[0104] "Microspheres" are understood as elastic and therefore expandable hollow microspheres (Mikrohohlkugeln) in their basic state, having a thermoplastic polymer shell. These spheres are filled with a low-boiling-point liquid or liquefied gas. The shell material used is particularly polyacrylonitrile, PVDC, PVC, or polyacrylate. Suitable low-boiling-point liquids are, in particular, lower alkanes such as isobutane or isopentane, which are encapsulated as liquefied gases within the polymer shell under pressure.

[0105] The action of heat exposure on the microspheres causes the outer polymer shell to soften. Simultaneously, the liquid propellant inside the shell transforms into its gaseous state. At this point, the microspheres undergo irreversible stretching and three-dimensional expansion. The expansion ends when the internal and external pressures reach equilibrium. Because the polymer shell is retained, a closed-cell foam is obtained.

[0106] Many types of microspheres are commercially available and vary significantly in their size (diameter in the unexpanded state: 6 to 45 μm) and the onset temperature required for their expansion (75 to 220 °C). For example, an example of commercially available microspheres is from Nouryon. DU products (DU = dry, unexpanded).

[0107] Unexpanded microsphere products can also be used as masterbatches in polymer-bonded form, for example, in ethyl vinyl acetate at a microsphere concentration of about 65% by weight. Like the DU product, the masterbatch is suitable for manufacturing the foamed pressure-sensitive adhesives of this invention.

[0108] The foamed pressure-sensitive adhesive of the present invention can also be produced using so-called pre-expanded microspheres. In this group, expansion occurs before introduction into the polymer matrix. Pre-expanded microspheres can be, for example, from Nouryon... The product name or product name Expansion DE (dry expanded) is available commercially.

[0109] According to the present invention, at least 90% of all voids formed by microspheres preferably have a maximum diameter of 20 to 75 μm, more preferably 25 to 65 μm. "Maximum diameter" refers to the maximum range of microspheres in any spatial direction.

[0110] The diameter was determined using a scanning electron microscope (SEM) at 500x magnification based on the frozen fracture edge. For each individual microsphere, the diameter was determined graphically.

[0111] When using microspheres for foaming, the microspheres can be supplied to the formulation as batches, pastes, or blended or unblended powders. They can also exist as suspensions in solvents.

[0112] The fraction of microspheres in the adhesive is between 0.5 wt% and 5 wt%, more particularly between 1.0 wt% and 2.5 wt%, based on the total composition of the total pressure-sensitive adhesive in each case. The data refer to unexpanded microspheres.

[0113] The polymer compositions used in this invention and comprising expandable hollow microspheres may additionally include non-expandable (non-expandable) hollow microspheres. The only critical factor is that almost all gas-containing cavities are sealed by a permanently impermeable membrane, whether the membrane consists solely of an elastic and thermoplastic stretchable polymer mixture or, for example, of an elastic and—within the temperature range possible in plastics processing—non-thermoplastic glass.

[0114] Other pressure-sensitive adhesives suitable for use in this invention, independent of other additive choices, are solid polymer spheres, hollow glass spheres, solid glass spheres, hollow ceramic spheres, solid ceramic spheres, and / or solid carbon spheres (“carbon microspheres”).

[0115] The total amount of additional components that may be used optionally may be up to about 20% by weight, but may also be up to 15% by weight, 10% by weight, or 5% by weight, based on the total weight of the total pressure-sensitive adhesive.

[0116] The present invention also covers cured pressure-sensitive adhesives that can be obtained or obtained by curing the pressure-sensitive adhesives described above.

[0117] adhesive tape:

[0118] The present invention also covers tapes comprising at least one layer of the pressure-sensitive adhesive or cured pressure-sensitive adhesive of the present invention as described above in their respective cases.

[0119] In a preferred embodiment, the tape is a transfer tape, which preferably consists of a single layer of pressure-sensitive adhesive or cured pressure-sensitive adhesive as described above in their respective cases.

[0120] In an alternative preferred embodiment, the tape comprises at least one carrier, i.e., a permanent carrier, on which a layer of pressure-sensitive adhesive or cured pressure-sensitive adhesive, as described above in each case, is applied to at least one side, preferably both sides. The carrier is preferably a foam carrier, more particularly a polyolefin, polyurethane, or polyacrylate foam carrier. A further preferred permanent carrier is a film carrier, which particularly contains a thermoplastic polymer such as polyester or polypropylene. This permanent carrier may be uniaxially or biaxially oriented.

[0121] In adhesive tape, the exposed outer surface of the adhesive layer may be equipped with a double-sided non-stick coating material, such as release paper or release film, also known as a backing. The backing (release paper, release film) is not part of the tape, but merely a means of its manufacture, storage, and / or use for further processing via die-cutting. Furthermore, unlike the tape carrier, the backing is not non-fixed (firmly) bonded to the adhesive layer.

[0122] Preferably, all layers are substantially cuboid in shape. More preferably, all layers are interconnected over their entire area. This interconnection can be optimized through pretreatment of the carrier surface.

[0123] In the general sense of this invention, the term "tape" (pressure-sensitive adhesive tape) encompasses all sheet-like structures such as two-dimensionally extended films or film portions (segments), strips having an extended length and a finite width, strip portions (segments), etc., and finally, die-cut pieces or labels. Therefore, the pressure-sensitive adhesive strip has a longitudinal extent (x-direction) and a transverse extent (y-direction). The pressure-sensitive adhesive strip also has a thickness (z-direction) perpendicular to both extents, wherein the width and length extents are several times larger than the thickness. The thickness is as uniform as possible, preferably identical, across the entire surface of the pressure-sensitive adhesive strip defined by its length and width.

[0124] The tape of the present invention is more particularly present in the form of a web. A web is an object whose length (in the x-direction) is several times greater than its width (in the y-direction), and whose width remains substantially the same and preferably identical along its entire length.

[0125] The formulations according to the invention are characterized by good peel adhesion and simultaneously improved thermal shear strength, and are therefore particularly suitable for use in pressure-sensitive tapes in applications requiring these properties. These applications include, for example, applications in the interior and exterior areas of motor vehicles, electronic applications in devices sold in hot countries, and use as construction tapes exposed to intense heat in summer. Tapes are particularly advantageous if they achieve the following performance properties (Table 2):

[0126] Required performance range Preferred performance range SAFT Test I thermal shear strength Minimum 150℃ Minimum 170℃ Peel adhesion Test II Adhesion strength Minimum 4N / cm Minimum 7N / cm

[0127] Table 2: Preferred performance properties of the tape.

[0128] Manufacturing method:

[0129] The present invention also relates to a method for manufacturing the tape of the invention, wherein a solvent-based adhesive is coated and dried, and thermal curing of the adhesive is carried out or initiated during the drying operation. Therefore, thermal curing or its initiation preferably occurs during the drying operation. Alternatively, curing can be achieved by radiation, for example, particularly UV radiation. UV initiation can be carried out independently of drying. Those skilled in the art will recognize that, in their respective cases, initiators suitable for thermal curing or photochemical curing will be used.

[0130] Therefore, the method for preparing the adhesive tape is preferably solvent-based. It is preferable to use at least one solvent having a boiling point of at least 75°C, preferably at least 90°C, at a pressure of 1013 mbar, and also having a calorific value greater than 7.5 cal. 1 / 2 cm -3 / 2 And less than 10 calories 1 / 2 cm -3 / 2 The Hildebrand parameter.

[0131] As a solvent, a mixture of polar solvents (e.g., ethyl acetate, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), 2-pentanone and / or butyl acetate) and non-polar solvents (e.g., toluene, methylcyclohexane and / or light gasoline) can be used additionally and preferably. When selecting a solvent for manufacturing a solvent-based adhesive, selection concepts typically known to those skilled in the art are used prior to application.

[0132] While solvent-based manufacturing methods offer advantages, solvent-free manufacturing methods are also conceivable.

[0133] In particular, those methods that cover continuous mixing components such as extruders. Example:

[0134] In the examples and comparative examples, percentages refer to weight %. Unless otherwise stated, the formulation components total 100% by weight in their respective cases, with solvents being ignored. In contrast, figures for the amount of initiator used are based on the amount of reactive resin component used.

[0135] raw material:

[0136] The raw materials used in the examples and comparative examples are as follows (Table 3).

[0137]

[0138]

[0139]

[0140] Table 3: Raw materials used in the embodiments and comparative examples of the present invention.

[0141] Manufacturing and properties of the tape sample:

[0142] To prepare the tape samples of Examples E1 to E18 and Comparative Examples V1 to V22, all the required formulation components (as shown in Table 3) for each case were dissolved in a solvent mixture of ethyl acetate / toluene / light gasoline (14 wt% / 30 wt% / 56 wt%). The initiator was added either supplied (K-Pure CXC 1613 solution) or internally dissolved (UVC 531 or Irgacure 290, each as a 33 wt% solution of methyl ethyl ketone), and the mixture was stirred for 30 minutes using a propeller stirrer. In each case, the solvent content in the resulting solution was 40 wt%. The solution was then coated onto a siliconized PET film accordingly.

[0143] Unless otherwise specified, pre-dry the samples at room temperature for 10 minutes, then dry at 120°C for 15 minutes. After drying, or drying and foaming, the adhesive layer thickness of the coating is 50 μm (within the usual tolerance range). Evaluate the tape samples after 24 hours. Details of the study can be found specifically in the Test Methods section.

[0144] I: Comparative Examples V1 to V22:

[0145] a) Formulation optimization:

[0146] In Comparative Examples V1 to V10, the amounts of the components of the base formulation (i.e., the elastomer component, the tackifier resin component, the reactive resin component, and the initiator for cationic curing of the reactive resin) were different in order to optimize the hot shear strength (SAFT) and peel adhesion on steel. The composition and properties of the tapes from Comparative Examples V1 to V10 are shown in Table 4.

[0147]

[0148]

[0149] Table 4: Composition and properties of tapes from comparative examples V1 to V10. a The K-Pure CXC 1613 solution fraction, expressed as a percentage by weight, is based on the amount of reactive resin Uvacure 1500.

[0150] V1 shows no Uvacure 1500 and therefore no epoxy-cured blends. SAFT results above 140°C cannot be achieved here.

[0151] V2 further shows that, because no initiator was added, the epoxide could not react under heat-curing conditions. The epoxide did not cure, and therefore its thermal stability was even worse than that of the control formulation V1. The epoxide here acts as a plasticizer.

[0152] V3 through V7 clearly demonstrate that, in terms of the fraction of each component, there exists only one specific channel (Korridor) within which both acceptable peel adhesion and excellent thermal stability can be achieved. All results using these combinations of raw materials exhibit excessively low thermal shear strength.

[0153] V8 shows that the initiator alone has no effect on the achievement of performance requirements.

[0154] Furthermore, V9 and V10 show that an excessively high fraction of cured reactive resin leads to a sharp decrease in peel adhesion, causing the tape to lose its pressure-sensitive adhesive properties.

[0155] b) Elastomer screening:

[0156] In Comparative Examples V11 to V15, the selected elastomers were varied. Here, in addition to 40 wt% of the corresponding elastomer, 40 wt% of tackifier resin (Piccolyte A 115), 20 wt% of reactive resin (Uvacure 1500), and 3 wt% of initiator solution (K-Pure CXC 1613 solution) were used, based on the amount of Uvacure 1500. Table 5 shows the SAFT temperatures of the elastomers used and the resulting tapes. Furthermore, the SAFT temperatures generated when the reactive resin Uvacure 1500 was omitted from the adhesive formulation in their respective cases are also reported (where the amounts of other components remained constant).

[0157]

[0158]

[0159] Table 5: SAFT values ​​of the elastomers used in comparative examples V11 to V15 and the resulting tapes. a Uvacure 1500 is available; b Uvacure 1500 is not available.

[0160] V11 to V15 show that only small property channels exist for the elastomer, within which epoxide compatibility of the polystyrene domain can be achieved.

[0161] c) Epoxide screening:

[0162] In Comparative Examples V16 to V22, the selected epoxide, i.e., the reactive resin, was varied. Here, in addition to 20 wt% of the corresponding epoxide, 40 wt% of elastomer (Kraton D1116), 40 wt% of tackifier resin (Piccolyte A 115), and 3 wt% of initiator solution (K-Pure CXC 1613 solution) were used, based on the amount of epoxide. Table 6 shows the corresponding epoxides used and the SAFT temperature of the resulting tapes.

[0163] V16 to V22 indicate that the solubility of epoxides plays an important role in achieving performance requirements.

[0164]

[0165] Table 6: SAFT values ​​of the epoxides (reactive resins) used in comparative examples V16 to V22 and the resulting tapes

[0166] II: Embodiments E1 to E18 according to the present invention:

[0167] a) The pressure-sensitive adhesive of the present invention based on polystyrene-polybutadiene block copolymer:

[0168] Table 7 shows the quantitative composition and properties of the tapes according to the invention from Examples E1 to E14, wherein the elastomer of the tapes is, in each case, a polystyrene-polybutadiene block copolymer in the form of Kraton D1116.

[0169]

[0170] Table 7: Composition and properties of the adhesive tapes according to the present invention from Examples E1 to E14. a The K-Pure CXC1613 solution fraction, expressed as a percentage by weight, is based on the amount of reactive resin Uvacure 1500. b Instead of 3% K-Pure CXC 1613 solution, 1.5% UVC 531 solution was used here, also based on Uvacure 1500 volumetrics.

[0171] Examples E1 to E14 specifically demonstrate that the fraction of the reactive resin according to the invention in the polystyrene-polybutadiene block copolymer matrix according to the invention results in high thermal shear strength after curing, while also satisfying the requirement for good peel adhesion.

[0172] b) Pressure-sensitive adhesives according to the invention based on polystyrene-polyisoprene block copolymers:

[0173] Table 8 shows the quantitative composition and properties of the tapes according to the invention from Examples E15 and E16, wherein the elastomer of the tapes is, in each case, a polystyrene-polyisoprene block copolymer in the form of Vector 4113.

[0174]

[0175] Table 8: Composition and properties of the adhesive tapes according to the invention from Examples E15 and E16. a The K-Pure CXC1613 solution fraction by weight, based on the volume of Uvacure 1500.

[0176] Examples E15 and E16 show that this concept can also be applied to polystyrene-polyisoprene block copolymers as matrix polymers.

[0177] c) Pressure-sensitive adhesives according to the invention containing a photoinitiator:

[0178] The other tape, E17, is prepared from 40 wt% Kraton HT1200 as an elastomer, 40 wt% Regalite R1090 as a tackifying resin, and 20 wt% Uvacure 1500 as a reactive resin. Instead of a thermal initiator, a photoinitiator in the form of a solution of Irgacure 290 is used, based on the reactive resin Uvacure 1500. The tape is prepared as a thermosetting tape, wherein it is subsequently cured by UV light irradiation using a mercury-doped UV lamp with a power of 160 W / cm on an Eltosch bandanlage at a web speed of 4 m / min.

[0179] The resulting tape had a SAFT temperature of 212°C and a peel adhesion of 5.1 N / cm on steel. Example E17 shows that a photoinitiator can also be used instead of a thermal initiator for curing.

[0180] d) Pressure-sensitive adhesive according to the invention, foamed with microspheres:

[0181] The manufacturing process of tape E18 differs from that of tape E13 in that, prior to coating onto the silicone-coated PET film, the adhesive solution is mixed with 1.5% by weight of expandable microspheres Expansion 920DUT40, wherein the microspheres are used in suspension form in light gasoline. The weight fraction of the microspheres is based on the dry weight of the solution to which they are added (i.e., the dry weight of the solution is set to 100%). Pre-drying at room temperature for 10 minutes and then drying at 100°C for 15 minutes produces an unfoamed tape. Another layer of silicone-coated PET film is then applied to the open sides of the tape, and the tape is foamed at 170°C for 1 minute.

[0182] The foamed tape has a SAFT temperature of 180°C and a peel adhesion of 5.7 N / cm on steel. Example E18 shows that even tapes using microsphere foaming can possess desired performance properties, such as, in particular, high thermal shear strength.

[0183] Test method:

[0184] Unless otherwise stated, all measurements were performed at 23°C and 50% relative humidity.

[0185] The mechanical and technical data of the adhesive are determined as follows:

[0186] Test I – Thermal Shear Strength (SAFT)

[0187] This test is used to quickly assess the shear strength of adhesive tape under temperature load. To do this, the tape under study is adhered to a temperature-controlled steel plate, a 50g load is applied, and the shear distance is recorded.

[0188] Sample preparation:

[0189] The tape to be studied (50μm transfer tape) was adhered to a 50μm thick aluminum foil with one adhesive side attached. The prepared tape was then cut into 10mm x 50mm pieces.

[0190] The trimmed tape is adhered with the other adhesive side to a polished steel test plate (material 1.4301, DIN EN 10088-2, surface 2R, surface roughness R) cleaned with acetone. a =30 to 60 nm, dimensions 50 mm * 13 mm * 1.5 mm), the adhesion is performed such that the adhesion area of ​​the sample is 13 mm * 10 mm in height * width, and the steel test plate protrudes 2 mm from the upper edge. Subsequently, it is rolled 6 times with a 2 kg steel roller at a speed of 10 m / min to fix it. The sample is then reinforced flush with a stable (firm) adhesive strip, which serves as a support for the distance sensor. The sample is then suspended by means of the steel plate, with the longer protruding end of the adhesive strip pointing vertically downwards.

[0191] Measurement:

[0192] A 50g weight is applied to the bottom of the sample to be measured. The steel test plate with the adhered sample is heated from 25°C to a final temperature of 200°C at a rate of 9K / min.

[0193] Using a distance sensor, the slip distance of the sample as a function of temperature and time was observed. The maximum slip distance was set at 1000 μm (1 mm); if exceeded, the test was stopped and the failure temperature was recorded. Test conditions: room temperature 23 ± 3 °C, relative humidity 50 ± 5%. Results were reported as the average of two separate measurements, in °C.

[0194] Test II – Peel Adhesion

[0195] The study was conducted according to PSTC-1. A 2 cm wide and 15 cm long strip of 50 μm thick adhesive tape was lined with a 25 μm thick PET film on one of its adhesive sides and adhered to a polished steel plate (ASTM) through the other adhesive side. Defined adhesion was ensured by rolling back and forth five times with a 4 kg roller. The plate was clamped and the self-adhesive strip was peeled off at a peel angle of 180° and a speed of 300 mm / min via the free end of the self-adhesive strip on a tensile testing machine. Test conditions were 23°C + / - 3°C / 50% + / - 5% indoor humidity (rH). Results are reported as the average of three individual measurements, in N / cm.

[0196] Test the glass transition temperature of the III-polymer block, DSC

[0197] The glass transition temperature of the polymer blocks in the block copolymer was determined by dynamic scanning calorimetry (DSC). For this determination, approximately 5 mg of untreated block copolymer sample was weighed into a small aluminum crucible (25 μl volume) and sealed with a perforated cap. Measurements were performed using a Netzsch DSC 204F1, operated under nitrogen atmosphere for inertization. The sample was first cooled to -150 °C, heated to +150 °C at a heating rate of 10 K / min, and then cooled again to -150 °C. A second heating curve was then run again at 10 K / min, and the change in heat capacity was recorded. The glass transition was identified as a step in the thermogram. The glass transition temperature was evaluated as follows: tangents were applied to the baseline of the thermogram, respectively, before and after step 1 and step 2. In the step region, the best-fit line 3 was placed parallel to the ordinate such that the two tangents intersected, specifically forming two regions 4 and 5 of equal area (between the corresponding tangent, the best-fit line, and the measurement plot). Therefore, the intersection of the best-fit line for the corresponding location and the measurement plot gives the glass transition temperature.

[0198] Test IV-molar mass, GPC

[0199] (a) Peak molar mass of the block copolymer mode alone:

[0200] GPC is suitable as a metrological method for determining the molar mass of individual polymer patterns in mixtures of different polymers. For block copolymers prepared by living anionic polymerization that are suitable for the purposes of this invention, the molar mass distribution is typically narrow enough to allow polymer patterns assigned to triblock copolymers, diblock copolymers, or multiblock copolymers to appear in the elution spectrum with sufficient resolution. The peak molar mass of the individual polymer patterns can then be read from the elution spectrum.

[0201] Peak molar mass M P The determination was performed by gel permeation chromatography (GPC). THF was used as the eluent. Measurements were taken at 25°C. A PSS-SDV, 10 μm, ID 8.0 mm x 50 mm preparative column was used. For separation, a PSS-SDV, 10 μm column was used. as well as and Each sample has an ID of 8.0 mm x 300 mm. The sample concentration is 3 g / L, and the flow rate is 1.0 ml / min. Measurements were performed relative to PS standards. Calibration was performed using the commercially available ReadyCal kit Poly(styrene)high from PSS Polymer Standard Service GmbH, Mainz (μ = μm). ).

[0202] (b) Weight-average molar mass of the tackifier resin in particular:

[0203] Weight-average molecular weight M w (MW) was determined by gel permeation chromatography (GPC). THF was used as the eluent. Measurements were performed at 25°C. A PSS-SDV, 10 μm column was used for preparation. ID 8.0mm x 50mm. For separation, a PSS-SDV column, 10μm, was used. as well as and Each sample has an ID of 8.0 mm x 300 mm. The sample concentration is 3 g / L, and the flow rate is 1.0 ml / min. Measurements are performed relative to PS standards. Calibration is performed using the commercially available ReadyCal kit Poly(styrene)high from PSS Polymer StandardService GmbH, Mainz (μ = μm). ).

[0204] Testing V-resin compatibility, DACP

[0205] Weigh 5.0 g of the test substance (the tackifying resin sample to be studied) into a dry test tube and add 5.0 g of xylene (a mixture of isomers, CAS [1330-20-7], ≥98.5%, Sigma-Aldrich #320579 or similar). Dissolve the test substance at 130 °C, then cool the solution to 80 °C. Replenish any xylene that has escaped with additional xylene, so that 5.0 g of xylene is present again. Then add 5.0 g of diacetone alcohol (4-hydroxy-4-methyl-2-pentanone, CAS [123-42-2], 99%, Aldrich #H41544 or similar). Shake the test tube until the test substance is completely dissolved. For this purpose, heat the solution to 100 °C. Then introduce the test tube containing the resin solution into a Novomatics ChemotronicCool cloud point measuring instrument and heat it to 110 °C. Cool at a cooling rate of 1.0 K / min. The cloud point was determined using optical methods. For this purpose, the temperature at which the solution reached 70% turbidity was recorded. Results were reported in °C. The lower the DAP, the higher the polarity of the tested substance.

[0206] Testing VI-resin compatibility, MMAP

[0207] Weigh 5.0 g of the test substance (the tackifying resin sample to be studied) into a dry test tube, and add 10 ml of dry aniline (CAS [62-53-3], ≥99.5%, Sigma-Aldrich #51788 or similar) and 5 ml of dry methylcyclohexane (CAS [108-87-2], ≥99%, Sigma-Aldrich #300306 or similar). Shake the test tube until the test substance is completely dissolved. For this purpose, heat the solution to 100°C. Then, introduce the test tube containing the resin solution into the Novomatics Chemotronic Cool cloud point measuring instrument and heat it to 110°C. Cool at a cooling rate of 1.0 K / min. The cloud point is detected optically. For this purpose, record the temperature at which the turbidity of the solution is 70%. The results are reported in °C. The lower the MMAP, the higher the aromaticity of the test substance.

[0208] Test VII - Resin softening temperature

[0209] The softening temperature of the tackifier resin was determined according to a relevant methodology known as the ring and ball method and standardized according to ASTM E28.

Claims

1. Pressure-sensitive adhesives, including: a) Basic formulation, containing (i) 25 to 45% by weight of at least one elastomer component comprising at least one polyvinyl aromatic compound-polydiene block copolymer, The polyvinyl aromatic compound-polydiene block copolymer wherein the polyvinyl group at least partially contains ABA, (AB) n (AB) n X or (ABA) n The X structure, in which - Block A is a polymer formed independently of each other by polymerization of at least one vinyl aromatic compound; - Block B is a polymer formed independently of each other by polymerization of a conjugated diene having 4 to 18 carbon atoms, or a derivative of such a polymer partially hydrogenated in a polydiene block; - X is a residue of the coupling agent or initiator; and - n is an integer ≥ 2, The at least one polyvinyl aromatic compound-polydiene block copolymer wherein the peak molar mass of test IVa is at least 160,000 g / mol. The fraction of the A block in the at least one polyvinyl aromatic compound-polydiene block copolymer is at least 8% by weight and at most 25% by weight, and Optionally, up to 25% by weight of a diblock copolymer AB comprising blocks A and B as defined above may be present, based on the total elastomer composition. (ii) 33 to 55% by weight of at least one tackifier resin component having at least one tackifier resin, wherein said at least one tackifier resin has a softening temperature of ≥80°C as measured by test VII according to the ring and ball method, and (iii) 13 to 30% by weight of at least one reactive resin component, comprising at least 70% by weight of a resin having a strength of 17.70 to 17.82 MPa. 1 / 2 The dispersive component δ of the Hansen parameter D At least one reactive resin based on cyclic ether, In their respective cases, based on the base formulation, the sum of the elastomer component and the reactive resin component is at least 38% by weight and at most 68% by weight. b) 0.1 to 5% by weight of at least one initiator for cationic curing of said at least one reactive resin, based on the amount of reactive resin component. c) Optionally at least one plasticizer, and d) Optionally, at least one additive.

2. The pressure-sensitive adhesive according to claim 1, wherein the at least one polyvinyl aromatic compound-polydiene block copolymer has a peak molar mass of at least 200,000 g / mol according to test IVa.

3. The pressure-sensitive adhesive according to claim 1, wherein the at least one tackifier resin has a softening temperature of ≥100°C as measured by test VII according to the ring and ball method.

4. The pressure-sensitive adhesive according to claim 1, wherein the at least one tackifier resin has a softening temperature of up to 130°C as measured by test VII according to the ring and ball method.

5. The pressure-sensitive adhesive according to claim 1, wherein the reactive resin component comprises at least 70% by weight of a resin having a pressure sensitivity of 17.70 to 17.80 MPa. 1 / 2 The dispersive component δ of the Hansen parameter D At least one reactive resin based on cyclic ether.

6. The pressure-sensitive adhesive according to claim 1, wherein the polyvinyl aromatic compound-polydiene block copolymer is a polystyrene-polybutadiene block copolymer, a polystyrene-polyisoprene block copolymer, or a polystyrene-polyfarnes block copolymer.

7. The pressure-sensitive adhesive according to claim 6, wherein the polyvinyl aromatic compound-polydiene block copolymer is a polystyrene-polybutadiene block copolymer.

8. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the polyvinyl aromatic compound-polydiene block copolymer is (i) a triblock copolymer ABA or (AB)2X and (ii) a radial (AB) n A mixture of X block copolymers, where n is an integer ≥3.

9. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the dispersion component δ of the Hansen parameter of the reactive resin is... D The dispersive component δ of the Hansen parameter of the polyvinyl aromatic compound of the at least one polyvinyl aromatic compound-polydiene block copolymer. D The difference is at most 2 MPa 1 / 2 .

10. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the at least one cyclic ether-based reactive resin is an epoxide or an oxetine.

11. The pressure-sensitive adhesive according to claim 10, wherein the at least one cyclic ether-based reactive resin is an epoxide.

12. The pressure-sensitive adhesive according to claim 10, wherein the at least one cyclic ether-based reactive resin is a diepoxide.

13. The pressure-sensitive adhesive according to claim 10, wherein the cyclic ether-based reactive resin is aliphatic or alicyclic in nature.

14. The pressure-sensitive adhesive according to claim 13, wherein the cyclic ether-based reactive resin is alicyclic in nature.

15. The pressure-sensitive adhesive according to claim 13, wherein the cyclic ether-based reactive resin is (3,4-epoxycyclohexyl)methyl 3,4-epoxycyclohexylcarboxylic acid ester.

16. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the initiator is selected from thermally activated initiators for initiating cationic curing, radiochemical initiators for initiating cationic curing, and mixtures thereof.

17. The pressure-sensitive adhesive according to claim 16, wherein the initiator is a UV initiator.

18. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the base formulation comprises 40 to 50% by weight of at least one tackifier resin component having at least one tackifier resin.

19. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the base formulation comprises 16 to 25% by weight of at least one reactive resin component.

20. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the sum of the elastomer component and the reactive resin component is at least 50% by weight and at most 60% by weight.

21. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the glass transition temperature of block A is at least 25°C, as determined by DSC, test III.

22. The pressure-sensitive adhesive according to claim 21, wherein the glass transition temperature of block A is at least 50°C.

23. The pressure-sensitive adhesive according to claim 21, wherein the glass transition temperature of block A is at least 75°C.

24. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the glass transition temperature of block B is at most 0°C, as determined by DSC, test III.

25. The pressure-sensitive adhesive according to claim 24, wherein the glass transition temperature of block B is at most -50°C.

26. The pressure-sensitive adhesive according to claim 24, wherein the glass transition temperature of block B is at most -75°C.

27. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the fraction of the diblock copolymer in the elastomer component is at most 20% by weight.

28. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the elastomer component contains no diblock copolymers at all.

29. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the molar mass of the tackifier resin, as determined according to test IVb, is between 500 and 5000 g / mol.

30. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the tackifier resin is one of those compatible with block B of the polyvinyl aromatic compound-polydiene block copolymer of the elastomer component.

31. The pressure-sensitive adhesive of claim 6, wherein if a polyisoprene block copolymer is present in the elastomer portion, the tackifier resin is a tackifier resin having a diacetone alcohol cloud point (DACP) greater than +5°C as measured by test V, in at least 90% by weight based on the tackifier resin component; and if a polyisoprene block copolymer is not present in the elastomer portion, the tackifier resin is a tackifier resin having a diacetone alcohol cloud point (DACP) less than +50°C as measured by test V, in at least 90% by weight based on the tackifier resin component.

32. The pressure-sensitive adhesive of claim 6, wherein if a polyisoprene block copolymer is present in the elastomer portion, the mixed methylcyclohexane aniline point MMAP of the at least one tackifier resin, as measured according to Test VI, is at least +50°C and at most +100°C; and if a polyisoprene block copolymer is not present in the elastomer portion, the mixed methylcyclohexane aniline point MMAP of the at least one tackifier resin, as measured according to Test VI, is at most +90°C.

33. The pressure-sensitive adhesive according to any one of claims 1 to 7, wherein the tackifier resin is a hydrocarbon resin or a polyterpene resin in at least 90% by weight.

34. The pressure-sensitive adhesive according to claim 33, wherein the tackifier resin is only a hydrocarbon resin or a terpene resin or a mixture thereof.

35. The pressure-sensitive adhesive of claim 16, wherein the thermally activated initiator for initiating cationic curing is present in a fraction of at least 0.2% by weight and at most 4.0% by weight relative to the reactive resin component.

36. The pressure-sensitive adhesive of claim 35, wherein the thermally activated initiator for initiating cationic curing is present in a fraction of at least 0.3% by weight and at most 2.5% by weight relative to the reactive resin component.

37. The pressure-sensitive adhesive of claim 16, wherein the radiochemical initiator for initiating cationic curing is present in a fraction of at least 0.2% by weight and at most 5% by weight relative to the reactive resin.

38. The pressure-sensitive adhesive of claim 37, wherein the radiochemical initiator for initiating cationic curing is present in a fraction of at least 0.5% by weight and at most 4% by weight relative to the reactive resin.

39. The pressure-sensitive adhesive of claim 16, wherein the heat-activated initiator for initiating cationic curing has an activation temperature of at least 25°C and at most 200°C.

40. The pressure-sensitive adhesive of claim 39, wherein the heat-activated initiator for initiating cationic curing has an activation temperature of at least 50°C and at most 150°C.

41. A cured pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive according to any one of claims 1 to 40.

42. A tape comprising at least one layer of pressure-sensitive adhesive according to any one of claims 1 to 40 or a layer of cured pressure-sensitive adhesive according to claim 41.

43. The tape according to claim 42, wherein the tape is a transfer tape.

44. The tape of claim 43, wherein the tape comprises a single layer of pressure-sensitive adhesive according to any one of claims 1 to 40 or a layer of cured pressure-sensitive adhesive according to claim 41.

45. The tape of claim 42, wherein the tape comprises at least one carrier having a layer of pressure-sensitive adhesive according to any one of claims 1 to 40 or a layer of cured pressure-sensitive adhesive according to claim 41 applied to at least one side.

46. ​​The tape of claim 45, wherein the carrier is provided with a layer of pressure-sensitive adhesive according to any one of claims 1 to 40 or a layer of cured pressure-sensitive adhesive according to claim 41 on both sides.

47. The tape according to claim 45, wherein the carrier is a foam carrier.

48. The tape of claim 47, wherein the carrier is a polyolefin, polyurethane, or polyacrylate foam carrier.

49. A method for preparing an adhesive tape according to any one of claims 42 to 48, wherein a solvent-containing adhesive is coated and dried, and thermal curing of the adhesive is carried out or initiated during the drying operation.

50. The method of claim 49, wherein at least one solvent is used, having a temperature of at least 75°C at a pressure of 1013 mbar, and further having a concentration greater than 7.5 cal. 1 / 2 cm -3 / 2 And less than 10 cal 1 / 2 cm -3 / 2 Hildebrand parameters.

51. The method of claim 50, wherein the solvent has a boiling point of at least 90°C at a pressure of 1013 mbar.

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