Pressure-sensitive adhesive

Abstract

An adhesive pressure-sensitive material based on at least one block copolymer should be provided, exhibiting good or improved properties, particularly temperature and aging stability, and suitable for use in elevated temperature ranges. This is achieved with an adhesive pressure-sensitive material based on at least one block copolymer BC, comprising at least one polymer block P(A) and at least one polymer block P(B), wherein - P(A) independently comprising homo- or copolymer blocks comprising a total of at least 80 wt% monomers A selected from the group consisting of methacrylic esters, methacrylamides and monomers with at least one polymerizable vinyl group; - P(B) independently comprising homo- or copolymer blocks comprising a total of at least 80 wt% monomers B selected from the group consisting of methacrylic esters, methacrylamides and monomers with at least one polymerizable vinyl group; characterized by the fact that - the monomers A to a total of at least 50 wt% one or more acrylate monomers A1 selected from the general structure CH2=C(H)(COOR 1 ) include; where R 1 in each occurrence is independently selected from a linear or branched hydrocarbon residue with 4 to 17 carbon atoms; - the monomers B to a total of at least 60 wt% one or more (meth)acrylate monomers B1 selected from the general structure CH2=C(R 2 )(COOR 3 ) include; where R 2 selected independently from H and CH3 for each occurrence; and R 3The compound is selected independently for each occurrence from an optionally substituted, cyclic or polycyclic alkyl group with at least 6 carbon atoms.

Description

[0001] The invention relates to pressure-sensitive adhesives based on at least one block copolymer, which are characterized by increased temperature stability and increased cohesion while simultaneously exhibiting high adhesive strength.

[0002] The demands on the stability of pressure-sensitive adhesives are constantly increasing. In particular, these adhesives are expected to exhibit excellent bonding properties even at high temperatures. To meet this need, (meth)acrylate block copolymers have emerged as a promising solution. These materials combine the advantageous properties of classic (meth)acrylate copolymers, such as aging resistance, water-clear transparency, and inherent tackiness, with the properties of styrene block copolymers, such as thermoreversible physical crosslinking and high cohesion.

[0003] Disadvantages of styrene block copolymer-based pressure-sensitive adhesives include, in the case of systems using unsaturated polymer chains in the elastomer block, e.g., when using styrene-isoprene-styrene (SIS) and styrene-butadiene-styrene (SBS) block copolymers, low aging resistance to ultraviolet radiation, as well as to thermo-oxidative degradation and ozonolysis. Thus, the advantage of water-clear transparent self-adhesive tapes cannot be fully utilized, as the adhesive must be protected from light exposure. This is achieved, for example, through light-absorbing additives such as titanium dioxide, the compounding of which leads to opaque products. Styrene block copolymers with chemically saturated elastomer blocks, e.g.,While the hydrogenated analogues of SBS and SIS, styrene-ethylene / butylene styrene (SEBS) and styrene-ethylene / propylene styrene (SEPS), exhibit significantly improved aging resistance, typically do not require light-absorbing additives, and can therefore be more easily processed into water-clear products, a disadvantage is that they typically do not achieve the favorable ratio of bond strength to low re-release forces known from SIS- and SBS-based pressure-sensitive adhesives. Furthermore, without the use of plasticizing agents (e.g., liquid resins, aliphatic oils), which are desirable for many formulations, the selection of sufficiently compatible adhesive resins is considerably more limited compared to, for example, SIS.

[0004] Commercially available block copolymers based on (meth)acrylates are limited by the choice of monomers used to form the various polymer blocks and the resulting glass transition temperature(s) of these blocks. Typically, commercially available block copolymers feature polymethyl methacrylate (PMMA) as the monomer of the hard (polymer) block, i.e., the block with a high glass transition temperature, and offer heat resistance that is also attributable to the glass transition temperature of PMMA. The limited use of monomers in commercial block copolymers means that the desired properties at high temperatures cannot be fully achieved. Therefore, there is a need for new, alternative block copolymer systems based on (meth)acrylates that exhibit very good or improved properties, particularly at high temperatures.

[0005] Several studies have been conducted on processes involving polar monomers, such as methacrylic or acrylic esters, in anionic polymerization. However, such polar monomers possess a residue, such as a carbonyl group, which is readily susceptible to nucleophilic attack. Therefore, achieving optimal conditions for viable polymerization during the anionic polymerization of a polar monomer is relatively difficult, as a side reaction of the monomer or an intermolecular cyclization reaction (so-called "backbiting") occurs at the growing end of the resulting polymer. Consequently, the selection of suitable monomers is limited, necessitating the development of alternative block copolymers based on different building blocks. Furthermore, anionic polymerization places very high demands on the reaction conditions, reaction control, and reactant purity.

[0006] The object of the invention is to provide an adhesive compound based on at least one block copolymer comprising essentially (meth)acrylic acid derivatives, which exhibits good adhesive strength, particularly on polar substrates, as well as good shear strength.

[0007] A first and general object of the invention, with which these problems are solved, is an adhesive compound based on at least one block copolymer BC, which comprises at least one polymer block P(A) and at least one polymer block P(B), wherein - P(A) independently comprising homo- or copolymer blocks comprising a total of at least 80 wt% monomers A selected from the group consisting of methacrylic esters, methacrylamides and monomers with at least one polymerizable vinyl group; - P(B) independently comprising homo- or copolymer blocks comprising a total of at least 80 wt% monomers B selected from the group consisting of methacrylic esters, methacrylamides and monomers with at least one polymerizable vinyl group; characterized by the fact that - the monomers A comprise a total of at least 50 wt% of one or more acrylate monomers A1 (“monomers A1”) selected from the general structure CH2=C(H)(COOR 1 ) include; where R 1 in each occurrence is independently selected from a linear or branched alkyl group with 4 to 17 carbon atoms (C atoms); - the monomers B to a total of at least 60 wt% one or more (meth)acrylate monomers B1 (“monomers B1”) selected from the general structure CH2=C(R 2 )(COOR 3 ) include; where R 2 selected independently from H and CH3 for each occurrence; and R 3The compound is selected independently for each occurrence from an optionally substituted, cyclic or polycyclic alkyl group with at least 6 carbon atoms, preferably with 6 to 14 carbon atoms.

[0008] In one embodiment, the adhesive compound is suitable for use at elevated temperatures, particularly in the temperature range up to 70 °C.

[0009] Details and embodiments of the invention are described below. Such embodiments, which are subsequently designated as preferred in any way, are combined in particularly preferred embodiments with features of other embodiments also designated as preferred in any way. Combinations of two or more of the embodiments subsequently designated as particularly preferred in any way are therefore especially preferred. Also preferred are embodiments in which a feature of one embodiment designated as preferred in any way is combined with one or more further features of other embodiments designated as preferred in any way.

[0010] Insofar as specific quantities or proportions of an element as well as preferred embodiments of the element are disclosed below, the specific quantities or proportions of the preferably embodiments are also disclosed. Furthermore, it is disclosed that, among the corresponding specific total quantities or proportions of the elements, at least some of the elements may be preferably embodiments, and in particular, that preferably embodiments may, in turn, be present within the specific total quantities or proportions.

[0011] In accordance with professional understanding, an adhesive is an adhesive that possesses pressure-sensitive properties, meaning it forms a permanent bond to a substrate even under relatively light pressure. Such adhesives or pressure-sensitive tapes are generally permanently tacky even at room temperature, meaning they exhibit a certain viscosity and tackiness, allowing them to wet the surface of a substrate even with minimal pressure. While not bound to this theory, it is often assumed that an adhesive can be considered an extremely highly viscous liquid with an elastic component, which consequently exhibits characteristic viscoelastic properties that lead to the permanent tackiness and pressure-sensitive adhesion described above.It is assumed that pressure-sensitive adhesives undergo mechanical deformation, resulting in both viscous flow processes and the development of elastic restoring forces. The viscous flow contributes to adhesion, while the elastic restoring forces are essential for cohesion. The relationships between rheology and pressure sensitivity are well-established in the art and are described, for example, in "Satas, Handbook of Pressure Sensitive Adhesives Technology," Third Edition, (1999), pages 153 to 203. The storage modulus (G') and the loss modulus (G'') are typically used to characterize the degree of elastic and viscous components. These can be determined using dynamic mechanical analysis (DMA), for example, with a rheometer.Within the scope of the present invention, an adhesive compound is preferably understood to be adhesive and thus a pressure-sensitive adhesive compound if, at a temperature of 23 °C in the deformation frequency range of 10° to 10. 1 rad / sec G' and G'' each at least partially in the range of 10 3 up to 10 7 Pa lie.

[0012] Block copolymers are macromolecules consisting of two or more covalently linked polymer blocks, for example, polymer block A "P(A)" and polymer block B "P(B)". The adjacent polymer blocks consist of constitutional units derived from different monomer species or from the same monomer species but with different compositions or sequence distributions of constitutional units. The specific molecular structure of the blocks usually results in microphase separation and thus in the formation of morphologies at the nanoscale level.

[0013] The block copolymer according to the invention is a polymer system. According to the invention, the term "polymer system" refers both to a single polymer and to a mixture of two or more different polymers. In accordance with the skilled person's understanding, a "polymer" or "a single polymer" is understood to mean not only a single macromolecule, but also a plurality of macromolecules that originate from one and the same polymerization process and exhibit a specific molar mass distribution among themselves.

[0014] The pressure-sensitive adhesive according to the invention is based on at least one block copolymer BC. "Based on" or "on the basis of" or "based on" means in this context that the properties of the pressure-sensitive adhesive are at least strongly determined by the fundamental properties of the at least one block copolymer BC, whereby it is of course not excluded that these properties may be further influenced by the use of modifying auxiliaries or additives in a composition. In particular, this may mean that the proportion of the at least one block copolymer BC in the total mass of the pressure-sensitive adhesive is more than 50 wt.%.

[0015] In one embodiment, the adhesive compound according to the invention comprises at least one block polymer BC to at least 50 wt.%, preferably to at least 60 wt.%, particularly preferably to 70 wt.% based on the total weight of the adhesive compound.

[0016] The block copolymer BC comprises at least one polymer block (A) and at least one polymer block P(B). Each polymer block P(A) independently represents either homoblocks or copolymer blocks of monomer A. Each polymer block P(B) independently represents either homoblocks or copolymer blocks of monomer B.

[0017] The polymer blocks P(A), as described in the main claim or in advantageous embodiments, can be polymer chains of a single monomer type made from monomers A or copolymers made from monomers of different structures made from monomers A. In particular, the monomers A used can vary in their chemical structure and / or in the length of the alkyl group. The polymer blocks thus encompass the range from completely homogeneous polymers to polymers made from monomers of the same basic chemical structure but different chain lengths, and from those with the same number of carbon atoms but different isomers, up to statistically polymerized blocks made from monomers of different lengths and different isomerism from group A. The same applies to the polymer blocks P(B) with respect to the monomers B, which can differ, for example, in their cyclic or polycyclic alkyl group.

[0018] An advantageous embodiment is if the block copolymers have a symmetrical structure such that polymer blocks P(A) and / or polymer blocks P(B) are identical in chain length and / or chemical structure.

[0019] Furthermore, all “asymmetrical” structures are also included, in which all of the polymer blocks P(A) and P(B) that occur fulfill the above-mentioned criteria on their own, but the chemical or structural identity of the individual building blocks is not a requirement.

[0020] The block copolymer according to the invention, which is present in at least two phases, comprises at least one polymer block P(A) and at least one polymer block P(B). Each polymer block P(A) independently represents a homoblock or copolymer block of monomer A, wherein the monomers A comprise one or more monomers selected from the group consisting of methacrylic esters, methacrylamides, and monomers with at least one polymerizable vinyl group. Each polymer block P(B) independently represents a homoblock or copolymer block of monomer B, wherein the monomers B comprise one or more monomers selected from the group consisting of methacrylic esters, methacrylamides, and monomers with at least one polymerizable vinyl group.

[0021] The monomers A comprise one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides, and monomers with at least one polymerizable vinyl group, comprising at least 80 wt.%, alternatively 85 wt.%, more preferably at least 90 wt.%, and particularly preferably at least 95 wt.%, and especially at least 98 wt.%. Most preferably, the monomers A comprise exclusively one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides, and monomers with at least one polymerizable vinyl group.

[0022] The monomers A according to the invention comprise a total of at least 50 wt.%, based on the total weight of the monomers A, of one or more acrylate monomers A1 selected from the general structure CH2=C(H)(COOR 1 ); where R 1Each occurrence is independently selected from a linear or branched alkyl group with 4 to 17 carbon atoms.

[0023] In further embodiments, the monomers A according to the invention comprise one or more monomers A1 in total at least 75 wt.%, at least 85 wt.%, at least 90 wt.%, at least 95 wt.%, at least 98 wt.% or 100 wt.% based on the total weight of the monomers A.

[0024] In one embodiment, the monomers A1 are selected from the group consisting of n-butyl acrylate, iso-butyl acrylate, iso-amyl acrylate, n-hexyl acrylate, n-heptyl acrylate, 2-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, n-octyl acrylate, iso-octyl acrylate, n-nonyl acrylate, iso-nonyl acrylate, 2-propylheptyl acrylate, n-decyl acrylate, iso-decyl acrylate, lauryl acrylate, tetradecyl acrylates, heptadecyl acrylate.

[0025] The monomers B comprise one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides, and monomers with at least one polymerizable vinyl group, comprising at least 80 wt.%, alternatively 85 wt.%, more preferably at least 90 wt.%, and particularly preferably at least 95 wt.%, and especially at least 98 wt.%. Most preferably, the monomers B comprise exclusively one or more monomers selected from the group consisting of methacrylic acid esters, methacrylamides, and monomers with at least one polymerizable vinyl group.

[0026] The monomers B according to the invention comprise a total of at least 60 wt.% one or more (meth)acrylate monomers B1 selected from the general structure CH2=C(R 2 )(COOR 3 ) include; where R 2 selected independently from H and CH3 for each occurrence; and R 3The monomer B1 is selected independently at each occurrence from an optionally substituted, cyclic or polycyclic alkyl group with at least 6 carbon atoms, preferably with 6 to 14 carbon atoms. Thus, the one or more (meth)acrylate monomers B1 exhibit the following properties as R: 3 a cyclic alkyl group which may optionally have further substituents or a polycyclic alkyl group which may optionally have further substituents.

[0027] Polycyclic alkyl groups R 3Examples include bridged cycloalkyl groups, such as norbornyl or isobornyl, as well as dicyclic and polycyclic groups like adamantyl, tricyclodecanyl, or dicyclopentanyl. In this document, the number of carbon atoms of a substituent refers to the total number of carbon atoms in that substituent, including any optional substituents. Thus, norbornyl is a cyclic carbon group with 7 carbon atoms, isobornyl is a cyclic carbon group with 10 carbon atoms, adamantyl is a polycyclic group with 10 carbon atoms, and dicyclopentanyl is a polycyclic group with 10 carbon atoms. In an example substitution of a norbornyl residue with a CN group, this residue would be called a cyclic residue with 8 C atoms.

[0028] R 3It may optionally have one or more substituents. For example, the optional substituents are independently selected from the group consisting of CN and halogens in each occurrence. Preferably, the substituent R has 3 a cyclic or polycyclic basic structure that includes further alkyl groups, preferably C1-C6 alkyl groups, particularly preferably methyl or ethyl, most preferably methyl. For example, the isobornyl group (C10) has the cyclic basic structure of the norbornyl group (C7), which has three further methyl groups (3x C1).

[0029] In further embodiments, the monomers B according to the invention comprise one or more monomers B1 in total at least 75 wt.%, at least 85 wt.%, at least 90 wt.%, at least 95 wt.%, at least 98 wt.% or 100 wt.% based on the total weight of the monomers B.

[0030] In one embodiment, the monomers B1 are selected from the group consisting of cyclohexyl acrylate, tert-butylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, cyclohexyl methacrylate, 2-acryloyloxy-2-methyladamantane, norbornyl acrylate, dicyclopentanyl acrylate, tricyclodecanol acrylate and isobornyl acrylate.

[0031] In one embodiment, the monomers B according to the invention comprise at least 60 wt% of one or more (meth)acrylate monomers B1 selected from the general structure CH2=C(R 2 )(COOR 3 ) include; where R 2 equals H; and R 3 The compound is selected independently for each occurrence from an optionally substituted, cyclic or polycyclic alkyl group with at least 6 carbon atoms.

[0032] In a preferred embodiment, the monomers B1 are selected from the general structure CH2=C(H)(COOR) 3 ); where R 3is selected independently at each occurrence from a cyclic or polycyclic alkyl group having a basic structure with at least 6 carbon atoms and optionally one or more methyl or ethyl substituents, wherein the R 3 has a total of 6 to 14, preferably 7 to 12, carbon atoms.

[0033] In a particularly preferred embodiment, the monomers B1 are selected from the general structure CH2=C(H)(COOR) 3 ); where R 3 in each occurrence is independently selected from a cyclic or polycyclic alkyl group having a basic structure with at least 6 carbon atoms and optionally one or more methyl substituents, wherein the R 3 has a total of 6 to 14, preferably 7 to 12, carbon atoms.

[0034] Surprisingly, the acrylate compounds as monomers B1 exhibit good adhesive strengths and shear strengths, which were otherwise only achieved with methacrylate compounds or styrene. Furthermore, acrylate compounds are characterized by their good commercial availability.

[0035] In one embodiment, R 3 a cyclic or polycyclic alkyl group with 6 to 14 carbon atoms, preferably with 7 to 12 carbon atoms.

[0036] In one embodiment, R 3 a polycyclic alkyl group with at least 7 carbon atoms.

[0037] In one embodiment, R 3 a bi- or tricyclic alkyl group with at least 7 carbon atoms.

[0038] In a preferred embodiment, the monomers B1 are selected from the group consisting of norbornyl acrylate, tricyclodecanol acrylate and dicyclopentanyl acrylate.

[0039] In one embodiment, R 3a tricyclic alkyl group with 10 carbon atoms.

[0040] In a preferred embodiment, R 3 a dicyclopentanyl substituent.

[0041] In a particularly preferred embodiment, the monomers B1 are equivalent to dicyclopentanyl acrylate.

[0042] In one embodiment, the block copolymer contains less than 17 wt% isobornyl acrylate.

[0043] In a preferred embodiment, the monomers B1 are not isobornyl acrylate. Allergic contact dermatitis has been observed with adhesives containing isobornyl acrylate when applied to the skin and in close-contact applications (such as watches / smartwatches).

[0044] The block copolymer according to the invention is a polymer system which preferably exists in at least two phases. Those skilled in the art understand this to mean that one phase is rich in, or essentially consists of, one component of the block copolymer, for example, polymer block P(A), and the other phase is rich in, or essentially consists of, another component, for example, polymer block P(B). The presence of small amounts of one component in the other, which does not preclude the formation of the multiphase structure, is considered negligible.

[0045] If the block copolymer according to the invention has more than two phases, the foregoing applies accordingly to all of these phases.

[0046] The phase separation is particularly preferably realized such that discrete regions (“domains”) rich in polymer block P(A) or polymer block P(B) – i.e., essentially composed of polymer block P(A) or polymer block P(B) – are present in a continuous matrix rich in the other polymer block – i.e., essentially composed of the other polymer block. A block copolymer according to the invention is considered to be present in at least two phases, in particular, if at least one of the following criteria a) - c) is met: a) Phase boundaries can be identified in a height profile analysis or an analysis of the Young modulus of an atomic force microscopy (AFM) image of the block copolymer. b) At least two independent glass transition temperatures are obtained from a Dynamic Differential Scanning Calorimetry (DSC) measurement performed on the block copolymer. c) At least two tan δ maxima are obtained from a Dynamic Mechanical Analysis (DMA) performed on the block copolymer.

[0047] According to the invention, a block copolymer BC consisting of at least two phases also comprises a microphase-separated block copolymer, i.e., a polymer system in which the discontinuous phase is present in a microscopically fine distribution.

[0048] In one embodiment, the adhesive compound according to the invention is based on at least one block polymer BC present in at least two phases.

[0049] The process according to the invention is intended to result in a polymer system consisting of at least two phases. Furthermore, it was an objective of the invention to provide the two- or multi-phase polymer system with the highest possible cohesion. Therefore, it seemed important to consider these and, if applicable, other properties of the final polymer system when selecting the monomers used in the two polymerization steps.

[0050] Monomers with a glass transition temperature of the homopolymer in question of ≤ 0 °C, more preferably of ≤ -10 °C, particularly of ≤ -20 °C, i.e., monomers that are particularly suitable for the polymer block P(A), are selected, for example, from the group consisting of ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, iso-amyl acrylate, n-hexyl acrylate, 2-heptyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, n-octyl acrylate, iso-octyl acrylate, n-nonyl acrylate, iso-nonyl acrylate, 2-propylheptyl acrylate, n-decyl acrylate, iso-decyl acrylate, lauryl acrylate, 2-[[(Butylamino)carbonyl]oxy]ethyl acrylate, 2-Cyanoethyl acrylate, 2-(2-Ethoxyethoxy)ethyl acrylate, phenoxyethyl acrylate, iso-stearyl acrylate, docosyl acrylate, and 2-[2-(2-Methoxyethoxy)-ethoxy]ethyl acrylate.

[0051] Monomers with a glass transition temperature of the homopolymer of ≥ 50 °C, more preferably ≥ 75 °C, and in particular ≥ 100 °C, i.e., monomers particularly suitable for polymer block P(B), are selected, for example, from the group consisting of dicyclopentanyl acrylate, isobornyl acrylate, norbornyl acrylate, benzyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, cyclohexyl acrylate, 4-[(6-acryloyloxy)hexyloxy]4'-cyanobiphenyl, N-succinimidyl acrylate, 1-ethylcyclopentyl acrylate, N-tert-octylacrylamide, N-tert-butylacrylamide, dimethyl acrylamide, diethyl acrylamide, acrylamide, N-[3-(dimethylamino)propyl]acrylamide, diacetone acrylamide, and N-(butoxymethyl)acrylamide. N-phenylacrylamide, N-[2-(dimethylamino)ethyl]acrylamide, N-[2-(diethylamino)ethyl]acrylamide, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, isobornyl methacrylate, glycerol formal methacrylate, 2-dimethylaminoethyl methacrylate, phenoxyethyl methacrylate, 9-anthrylmethyl methacrylate,2-Ethyl-2-adamantylmethacrylat, 2-(Acetoacetyloxy)ethylmethacrylat, 2-Isopropyl-2-methacryloyloxyadamantan, isoPropylmethacrylat, iso-Butylmethacrylat, tert-Butylmethacrylat, Furfurylmethacrylat, 2-Methacryloyloxy-2-methyladamantan, Phenylmethacrylat, N-Succinimidylmethacrylat, 2-(tert-Butylamino)ethylmethacrylat, 2-Cyclohexylpropan-2-ylmethacrylat, 1-Adamantylmethacrylat, 1-Methylcyclopentylmethacrylat, 3-Dimethylaminopropylmethacrylamid, N-tert-Butylmethacrylamid, N-(Methoxymethyl)methacrylamid, N,N-Dimethylmethacrylamid, Methacrylamid, N-Phenylmethacrylamid, N,N-Dimethylmethacrylamid, N-Vinylformamid, N-Vinylpyrrolidon, N-Vinylcaprolactam, N-Vinylcrbazol, N-Vinylimidazol, Vinylmethyloxazolidinon und N-Vinyl-N-methylacetamid.,

[0052] Against this background, in one embodiment of the invention, the monomers A comprise at least 50 wt.%, more preferably at least 60 wt.%, in particular at least 75 wt.%, of one or more monomers with a glass transition temperature of the homopolymer in question of ≤ 0 °C, more preferably of ≤ -10 °C, in particular of ≤ -20 °C; and the monomers B comprise at least 60 wt.%, more preferably at least 70 wt.%, in particular at least 80 wt.%, of one or more monomers with a glass transition temperature of the homopolymer in question of ≥ 50 °C, more preferably of ≥ 75 °C, in particular of ≥ 100 °C, wherein - unless otherwise specified - the glass transition temperatures are determined by means of method 1 (see section Measurement and Testing Methods).

[0053] In a further embodiment of this embodiment, the monomers A preferably comprise at least 50 wt.%, more preferably at least 60 wt.%, in particular at least 75 wt.%, one or more monomers A1, and the monomers B comprise at least 60 wt.%, more preferably at least 70 wt.%, in particular at least 80 wt.%, one or more monomers B1.

[0054] More preferably, the monomers A comprise at least 50 wt.%, more preferably at least 60 wt.%, and in particular at least 75 wt.%, one or more monomers selected from the group consisting of n-butyl acrylate, iso-amyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, iso-octyl acrylate, n-octyl acrylate, 2-propylheptyl acrylate, n-decyl acrylate, and iso-decyl acrylate; and the monomers B comprise at least 60 wt.%, more preferably at least 70 wt.%, and in particular at least 80 wt.%, one or more monomers selected from the group consisting of 3,3,5-trimethylcyclohexyl acrylate, dicyclopentanyl acrylate, isobornyl acrylate, tricyclodecanol acrylate, and norbornyl acrylate.

[0055] In a further development of this embodiment, the monomers A preferably comprise a total of at least 50 wt.%, more preferably a total of at least 60 wt.%, in particular a total of at least 75 wt.%, one or more monomers A1, a total of up to 35 wt.%, more preferably a total of up to 25 wt.%, in particular a total of up to 20 wt.%, one or more monomers selected from the group consisting of dicyclopentanyl acrylate, tricyclodecanol acrylate, isobornyl acrylate, norbornyl acrylate, methyl methacrylate, dimethyl acrylamide, diethyl acrylamide, 4-tert-butylcyclohexyl acrylate, tert-butyl acrylate, tert-butyl methacrylate, cyclohexyl methacrylate and cyclohexyl acrylate, and a total of up to 10 wt.%, one or more functionalized monomers; and the monomers B comprise a total of at least 60 wt.%, more preferably a total of at least 70 wt.%, in particular a total of at least 80 wt.%.-% one or more monomers B1; and a maximum total of 10 wt% of one or more functionalized monomers, wherein the functionalized monomers are selected from the group consisting of hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, 4-hydroxyethyl acrylamide, acrylic acid, methacrylic acid, 2-acryloyloxyethyl succinate, methacryloxyethyl succinate, sulfoethyl methacrylate, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexyl methyl acrylate, 3,4-epoxycyclohexyl methyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, 4-hydroxybutyl methacrylate glycidyl ether, isocyanatoethyl acrylate, isocyanatoethyl methacrylate. 2-[2- (Methacryloyloxy)ethyloxy]ethyl isocyanate, 2-[2-(Acryloyloxy)ethyloxy]ethyl isocyanate and α,α- Dimethyl-m-Isopropenylbenzyl isocyanate.

[0056] In particular, the monomers A comprise a total of at least 50 wt.%, more preferably at least 60 wt.%, and in particular at least 75 wt.%, one or more monomers selected from the group consisting of n-butyl acrylate, iso-amyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, iso-octyl acrylate, n-octyl acrylate, 2-propylheptyl acrylate, n-decyl acrylate and iso-decyl acrylate; a total of at most 35 wt.%, more preferably at most 25 wt.%, and in particular at most 20 wt.%, one or more monomers selected from the group consisting of dicyclopentanyl acrylate, isobornyl acrylate, norbornyl acrylate, methyl methacrylate, dimethylacrylamide, and a total of at most 10 wt.%.-% one or more monomers selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 3,4-epoxycyclohexyl methyl acrylate, 3,4-epoxycyclohexyl methyl methacrylate, glycidyl acrylate and glycidyl methacrylate; and the monomers B comprise a total of at least 60 wt.%, more preferably a total of at least 70 wt.%, in particular a total of at least 80 wt.%, one or more monomers selected from the group consisting of dicyclopentanyl acrylate, isobornyl acrylate and norbornyl acrylate; and a total of at most 10 wt.%.-% one or more monomers selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 3,4-epoxycyclohexyl methyl acrylate, 3,4-epoxycyclohexyl methyl methacrylate, glycidyl acrylate and glycidyl methacrylate.

[0057] In one embodiment, the monomers A and monomers B comprise a total of a maximum of 15 wt.%, preferably a total of a maximum of 10 wt.%, and particularly preferably a total of a maximum of 5 wt.% methyl methacrylate.

[0058] In a further development of this embodiment, at least the monomers B are essentially free of methyl methacrylate; more preferably, they are free of methacrylic acid esters and methacrylamides; in particular, they are free of any methacrylic compounds.

[0059] Preferably, the monomers A are essentially free of methyl methacrylate; more preferably, they are free of methacrylic acid esters and methacrylamides; in particular, they are free of any methacrylic compounds.

[0060] In a further development of these embodiments, monomers A and monomers B are essentially free of methyl methacrylate; more preferably, they are free of methacrylic acid esters and methacrylamides; in particular, they are free of any methacrylic compounds.

[0061] Essentially free of methyl methacrylate means that the monomers (A and / or B) contain less than 1 wt.%, preferably less than 0.5 wt.%, based on the total composition of methyl methacrylate, and particularly preferably no methyl methacrylate.

[0062] As has been shown, the exclusion of the aforementioned compounds has a beneficial effect on the polymerization rate.

[0063] In one embodiment, the block copolymer BC has a weight-average molar mass M w ≥ 200,000 g / mol, preferably M w ≥ 350,000 g / mol, particularly preferred M w ≥ 500,000 g / mol.

[0064] In one embodiment, the block copolymer BC has a polydispersity PD that is greater than 2, alternatively greater than 4 or greater than 6.

[0065] In one embodiment, the at least one polymer block P(A) and / or the at least one polymer block P(B) has a weight-average molar mass Mw ≥ 100,000 g / mol, preferably Mw ≥ 150,000 g / mol, particularly preferably Mw ≥ 200,000 g / mol.

[0066] In one embodiment, the block copolymer BC exists as a multimodal block copolymer. A multimodal block copolymer is understood to be a block copolymer with at least a bimodal mass distribution, i.e., a molar mass distribution with at least two maxima.

[0067] In one embodiment, the block copolymer BC comprises polymer blocks P(B) in a proportion between 5 and 49 wt.%; preferably between 7.5 and 35 wt.%; in particular between 10 and 30 wt.%; based on the total of the polymer blocks P(A) and P(B) of the block copolymer BC.

[0068] The ratios of the chain lengths of the block copolymers P(A) to those of the block copolymers P(B) are advantageously selected such that the block copolymers P(B) exist as a dispersed phase ("domains") within a continuous matrix of polymer blocks P(A). This is preferably the case when the polymer block content P(B) is less than approximately 25 wt.%. The formation of hexagonally packed cylindrical domains of the polymer blocks P(B) is also possible according to the inventive teaching, but is usually not preferred due to the less favorable tensile / elongation characteristics of such materials and the structural anisotropy of the resulting pressure-sensitive adhesives induced by the domain structure.By using an asymmetric design of the triblock copolymers, where the block lengths of the terminal polymer blocks P(B) differ in linear systems, the content of polymer blocks P(B), at which the system still exhibits a spherical morphology, can be increased to above approximately 30 wt.%. This is particularly advantageous when an increase in the internal strength of the pressure-sensitive adhesive is required, as well as for improving its mechanical properties.

[0069] In one embodiment, the structure of at least one block copolymer BC, preferably several or all block copolymers BC, can be described by one or more of the following general formulas: - P(A)−P(B)−P(A) - P(B)−P(A)−P(B) - P(B)−P(A)−P(B)−P(A)−P(B) - P(A)−P(B)−P(A)−P(B)−P(A) - [P(A)−P(B)]nX - [P(B)−P(A)]nX - [P(B)−P(A)−P(B)]nX - [P(A)−P(B)−P(A)]nX - [P(A)−P(B)]nX[P(B)]m - [P(B)−P(A)]nX[P(A)]m where n = 2 to 12, m = 1 to 12 and X represents a di- or multifunctional branching region.

[0070] The polymer blocks P(A), as described in the main claim or in advantageous embodiments, can be polymer chains of a single monomer type from monomers A or copolymers of monomers with different structures from monomers A. In particular, the monomers A used can vary in their chemical structure and / or side chain length. The polymer blocks thus encompass the range from completely homogeneous polymers to polymers of monomers with the same basic chemical structure but different chain lengths, and those with the same number of carbon atoms but different isomers, up to statistically polymerized blocks of monomers of different lengths and isomers from group A. The same applies to the polymer blocks P(B) with respect to the monomers from group B.

[0071] The unit P(A)-P(B)-P(A) can be symmetrical [corresponding to P 1 (A)-P(B)-P2 (A) with P 1 (A) = P 2 (A)] as well as asymmetrical [approximately according to formula P 3 (A)-P(B)-P 4 (A) with P 3 (A) ≠ P 4 (A), but both P 3 (A) as well as P 4 (A) each polymer blocks in the sense of the definition for P(A)] are constructed.

[0072] An advantageous embodiment is when at least one block copolymer, preferably several or all block copolymers, have a symmetrical structure such that polymer blocks P(A) and / or polymer blocks P(B) are identical in chain length and / or chemical structure. 3 (A) and P 4 (A) may differ in particular in their chemical composition and / or chain length.

[0073] In a preferred embodiment, at least one block copolymer BC, preferably several or all block copolymers BC, has at least one, particularly preferably two terminal groups P(B).

[0074] For an advantageous further development according to the invention, adhesive resins can be added to the block copolymer-containing pressure-sensitive adhesives. In principle, all resins soluble in the corresponding polymer block P(A) can be used. Suitable adhesive resins include, among others, rosin and rosin derivatives (rosin esters, also rosin derivatives stabilized by, for example, disproportionation or hydrogenation), polyterpene resins, terpene phenolic resins, alkylphenolic resins, aliphatic, aromatic, and aliphatic-aromatic hydrocarbon resins, to name just a few. Resins that are preferably compatible with polymer block (A) are preferred. The weight fraction of the resins in the block copolymer is typically up to 40 wt.%, more preferably up to 30 wt.%. For a specific embodiment of the invention, resins that are compatible with polymer block P(B) can also be used.

[0075] Optionally, plasticizers, fillers (e.g., fibers, carbon black, zinc oxide, titanium dioxide, chalk, solid or hollow glass spheres, microspheres made of other materials, silicic acid, silicates), nucleating agents, blowing agents, compounding agents and / or anti-aging agents, e.g., in the form of primary and secondary antioxidants or in the form of light stabilizers, may also be added.

[0076] Preferably, the internal strength (cohesion) of the pressure-sensitive adhesive is generated by the physical cross-linking of the polymer blocks P(B). The resulting physical cross-linking is typically thermoreversible. For non-reversible cross-linking, the pressure-sensitive adhesives can be additionally chemically cross-linked. For this purpose, the acrylate block copolymer-containing pressure-sensitive adhesives can optionally contain compatible cross-linking agents. Suitable cross-linking agents include, for example, metal chelates, multifunctional isocyanates, multifunctional amines, or multifunctional alcohols. Multifunctional acrylates can also be advantageously used as cross-linking agents for actinic irradiation.

[0077] In a further embodiment of the pressure-sensitive adhesive compound designed according to the invention, polymer blocks P(A) and / or P(B) are functionalized such that thermally initiated crosslinking can be carried out. Suitable crosslinkers include, among others, epoxides, aziridines, isocyanates, polycarbodiimides, and metal chelates, to name just a few.

[0078] For optional crosslinking with UV light, UV-absorbing photoinitiators are added to the polyacrylate-containing block copolymers used in the systems according to the invention. Useful photoinitiators that are very suitable for use include benzoin ethers, such as benzoin methyl ether and benzoin isopropyl ether; substituted acetophenones, such as 2,2-diethoxyacetophenone (available as Irgacure 651® from Ciba Geigy®), 2,2-dimethoxy-2-phenyl-1-phenylethanone, dimethoxyhydroxyacetophenone; substituted α-ketols, such as 2-methoxy-2-hydroxypropiophenone; aromatic sulfonyl chlorides, such as 2-naphthyl sulfonyl chloride; and photoactive oximes, such as... B. 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime.

[0079] In an alternative embodiment, the adhesive compound according to the invention does not contain a crosslinker.

[0080] In a preferred embodiment, the adhesive compound according to the invention has an adhesive strength on steel, which is determined according to method 5, of at least 3 N / cm.

[0081] In a preferred embodiment, the adhesive compound according to the invention has a SAFT value, which is determined according to method 7, of at least 90 °C, preferably at least 120 °C.

[0082] In a preferred embodiment, the adhesive compound according to the invention has a shear life at room temperature, which is determined according to method 4, of at least 10,000 minutes.

[0083] In a particularly preferred embodiment, the adhesive compound according to the invention has a shear life at 70°C, which is determined according to method 4, of at least 100 minutes, preferably at least 300 minutes.

[0084] Particularly preferred embodiments of the adhesive compounds according to the invention have an adhesion strength on steel, determined according to method 5, of at least 3 N / cm; a SAFT value, determined according to method 7, of at least 90 °C, preferably at least 120 °C; a shear life at room temperature, determined according to method 4, of at least 10,000 minutes; and a shear life at 70 °C, determined according to method 4, of at least 100 minutes, preferably at least 300 minutes.

[0085] Another object of the invention is a method for producing an adhesive compound according to the invention based on at least one block copolymer BC, characterized in that at least one polymerization step takes place in a closed shell and / or at least one polymerization step is a RAFT polymerization.

[0086] In principle, all controlled or live polymerization processes can be used to produce the BC block copolymers for the pressure-sensitive adhesive according to the invention, as well as combinations of different controlled polymerization processes. These include, but are not limited to, anionic polymerization, ATRP, nitroxide / TEMPO-controlled polymerization, or, more preferably, the RAFT process – in particular, processes that allow control of the block lengths, polymer architecture, or, but not necessarily, the tacticity of the polymer chain.

[0087] In one embodiment, the block copolymer BC is produced in two polymerization steps, the first polymerization step being carried out in the presence of a RAFT regulator.

[0088] The process for producing at least one block copolymer BC comprises the following steps: a) the polymerization of a polymer block from monomers A to polymer block P(A) or from monomers B to polymer block P(B); and b) the polymerization of a further polymer block from monomers A to polymer block (A) or from monomers B to polymer block (B) to the polymer block from step a) to form a block copolymer existing in at least two phases; wherein the monomers A and the monomers B are each used in one of the polymerization steps a) or b), and preferably a RAFT regulator is used in step a). In a further development, at least one polymerization step takes place in a closed shell.

[0089] The RAFT polymerization of step a) can, in principle, be carried out in any manner. For example, it can be carried out in solvents, in particular in solvents in a conventional reactor designed for such polymerizations.

[0090] The RAFT polymerization of step b) can also be carried out in any way imaginable. For example, it can be carried out in solvents, in particular in solvents in a conventional reactor designed for such polymerizations.

[0091] In one embodiment, the polymerization of step a) takes place in a reactor, in particular in a reactor designed for processing highly viscous masses, or in a closed shell; more preferably, it takes place in a planetary mixer or in a closed shell.

[0092] The polymerization of step a) is also preferably carried out in the absence of solvent. Minimal solvent concentrations, e.g., resulting from production residues or at the level of ubiquitous solvent concentrations, are considered negligible.

[0093] "RAFT polymerization" stands for "reversible addition-fragmentation chain transfer polymerization." This refers to a polymerization process in which the reaction is controlled by reversible chain transfer reactions. In this process, an active, growing radical chain adds to a specific regulatory substance, the so-called RAFT agent, which is already bound to another chain and thus exists as a higher molecular weight RAFT agent (macro-RAFT agent). The addition of the active radical chain creates an intermediate that, due to its structure, can fragment in various directions. This process generates another macro-RAFT agent and an active radical chain available for propagation, the latter of which does not necessarily correspond to the previous active radical chain. In this way, the propagation probability is evenly distributed across all chains, typically resulting in a narrow molecular weight distribution.

[0094] In a preferred embodiment of this embodiment, the polymerization of step a) and step b) is a controlled radical polymerization, particularly preferably a RAFT polymerization.

[0095] In accordance with the above, at least one of the polymerization steps, preferably all polymerization steps, is carried out in the presence of at least one regulator substance containing at least one sequence -SC(=X)-, wherein X represents S, O or NR', where R' represents an organic residue.

[0096] The regulator substance containing at least one sequence -SC(=X)- is preferably selected from the group consisting of

[0097] Dithioesters, i.e. compounds of the general structure (1)

[0098] Dithiocarbonates, i.e. compounds of the general structure (2)

[0099] Xanthates, compounds of the general structure (3)

[0100] Dithiocarbamates, compounds of the general structure (4)

[0101] Trithiocarbonates, i.e., compounds of the general structure (5), and imido-dithiocarbonates, i.e., compounds of the general structure (6), wherein in the general structures (1) to (6), the substituents R each independently represent an organic or inorganic, preferably an organic, residue. In particular, at least one substituent R in the general structures (1) to (6) comprises a polymer chain formed during the polymerization in the relevant step.

[0102] Particularly preferred is the regulator substance containing at least one sequence -SC(=X)- selected from trithiocarbonates and xanthates; in the foregoing sense, therefore preferably from compounds according to the general structures (3) and (5).

[0103] Particularly preferred is the regulator substance containing at least one sequence -SC(X)- in its original state, i.e. without encompassed growing polymer chains, selected from the group consisting of dibenzyltrithiocarbonate, O-ethyl-S-(1-methyloxycarbonyl)ethylxanthate, 1,4-phenylenebis(methylene)didodecyltricarbonotrithioate, 2,2'-[Carbonothioylbis(thio)]bis[2-methylpropanoic acid] and 4-cyano-4-(((dodecylthio)carbonothioyl)thio)pentanoic acid.

[0104] For advantageous further development according to the invention, initiator systems can also be used in the manufacturing process, in particular thermally decomposing radical-forming azo or peroxide initiators. In principle, however, all conventional initiators known for acrylates are suitable for this purpose. The production of C-centered radicals is described in Houben-Weyl, Methods of Organic Chemistry, Vol. E19a, pp. 60ff. These methods are preferably used. Examples of radical sources are peroxides, hydroperoxides, and azo compounds. Some non-exclusive examples of typical radical initiators are: potassium peroxodisulfate, dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, cyclohexylsulfonylacetyl peroxide, di-tert-butyl peroxide, azodiisobutyronitrile, diisopropyl percarbonate, tert-butyl peroctoate, and benzpinacol.In a highly preferred embodiment, 1,1'-azo-bis-(cyclohexylnitrile) (Vazo 88®, DuPont®) or 2,2-azo-bis-(2-methylbutanitrile) (Vazo 67®, DuPont®) is used as the radical initiator. Photoinitiators can also be used as radical sources. A "photoinitiator" is defined as a substance that forms radical species under the influence of light of certain wavelengths, usually at least under the influence of UV radiation, and optionally also under UV radiation in the wavelength range of visible light (approximately 300–500 nm). The photoinitiator forming at least one radical is preferably selected from the group consisting of 1-hydroxycyclohexyl phenyl ketone and 2,2-dimethoxy-2-acetophenone.

[0105] To produce an adhesive, in particular a pressure-sensitive adhesive, in an extrusion process, the polymer system according to the invention, which optionally exists in a closed shell, is heated in the extruder to a temperature at which the shell material melts and can thus be homogeneously incorporated into the polymer system. As has been shown, the influence of the shell material on the properties of the adhesives produced with the polymer system according to the invention is below the threshold of technical relevance. The polymer system is heated to such an extent that it is deformable, in particular flowable. As has been found, the special polymer systems of the present invention often exhibit lower viscosities and thus better deformability and flowability than conventional polymers used, in particular, for the production of pressure-sensitive adhesives.The polymer system according to the invention can thus be processed into an adhesive mass in an extruder under the influence of heat and shear, optionally also with the incorporation of further components, and finally formed. The temperatures typically used in this process do not lead to the decomposition of the regulatory substances incorporated into the polymer backbones and therefore also not to polymer degradation. A significant advantage of the invention is that no solvent removal is required before processing the polymer systems in the extruder, a process that regularly leads to the degradation processes just described.

[0106] Further processing steps, such as mixing with additives, filtration, or degassing, can also take place in the extruder. The resulting adhesive, particularly pressure-sensitive adhesive, can then be formed into a desired layer shape, for example, using a calender onto a substrate or release liner. During the processing of the polymer system into an adhesive, especially a pressure-sensitive adhesive, the polymer system can be mixed with other components. These additional components can be selected from the following groups: other polymers; adhesive-enhancing resins; fillers, such as electrically conductive fillers, thermally conductive fillers, and the like; flame retardants, such as ammonium polyphosphate and its derivatives; foaming agents; antioxidants; light stabilizers; plasticizers; and compounding particles.

[0107] The adhesive compound according to the invention can be used as such, e.g., in the form of a layered body or a carrier-free layer of the adhesive compound according to the invention, which is also referred to as "transfer adhesive tape". Such a transfer adhesive tape is preferably applied only to a material that temporarily serves to protect the adhesive surface, to facilitate handling, and to make the adhesive compound easier to apply.

[0108] These materials are also known as release liners or simply "liners" and are generally easy to remove, especially due to suitable surface coatings. The other side of the transfer tape can also be coated with a liner.

[0109] Release liners are carrier materials that are coated or treated with an anti-adhesive finish on one or, preferably, both sides. Suitable carrier materials for release liners include various papers, optionally in combination with a stabilizing extrusion coating. Other suitable liner carrier materials are films, especially polyolefin films, for example, based on ethylene, propylene, butylene, and / or hexylene. Preferred carrier materials are papers, such as glassine papers. Papers are preferred, not least because the concept of using components derived from renewable raw materials can thus be extended to the adhesive tape's auxiliary materials.

[0110] Silicone systems are frequently used as anti-adhesive release liners. Commonly used liners include, for example, siliconized papers and siliconized films.

[0111] For using the transfer tape to bond to a substrate surface, the liner(s) are removed so that the two adhesive sides make direct contact with the substrate surfaces to be bonded. The liner is therefore not a productive component and is not considered part of the tape itself, but rather merely an aid for handling it.

[0112] The adhesive compound according to the invention can also be used in the construction or production of multilayer adhesive tapes. Such multilayer adhesive tapes typically comprise at least one carrier layer and can have an outer layer of the adhesive compound according to the invention on one or both sides. In the case of double-sided adhesive tapes, either one or both outer layers can be adhesive compounds according to the invention. In the latter case, the adhesive layers can differ with respect to their chemical composition and / or their chemical and / or physical properties and / or their geometry (e.g., layer thickness); however, they are particularly preferably identical with respect to their chemical composition and / or their chemical and / or physical properties.Even with multi-layered adhesive tapes, one or both outer adhesive layers can be covered with liners.

[0113] The adhesive tapes may have additional layers, e.g., additional backing layers, functional layers, or the like.

[0114] Bio-based materials are preferably selected as backing materials for the multilayer adhesive tape, for example, those selected from the following list: papers; bio-based woven or nonwoven fabrics, for example, made of cotton or viscose; cellophane; cellulose acetate; bio-based polyethylene (PE) and polypropylene (PP) films; films made of thermoplastic starch; bio-based polyester films, e.g., films made of polylactic acid (PLA), polyethylene terephthalate (PET), polyethylene tetrahydrofuranoate (PEF), or polyhydroxyalkanoate (PHA). A PET film is particularly preferred as the backing material. PET films are preferred, for example, because they can be used as a recycled material and thus meet the requirements of sustainability.

[0115] For the adhesion of the pressure-sensitive adhesive to the carrier or another substrate, it can be advantageous to treat the adhesive and / or the substrate with corona or plasma before coating. Furthermore, for the adhesion of the pressure-sensitive adhesive layer to subsequent layers, especially to a carrier layer, it can be advantageous to use chemical bonding, e.g., via a primer. Examples of measurement and testing methods: Method 1 - Determination of the glass transition temperature of polymers

[0116] The static glass transition temperature of the polymers was determined using Dynamic Scanning Calorimetry (DSC). For this purpose, 5 mg of an untreated sample of the polymer in question was weighed into an aluminum crucible (volume 25 µl) and sealed with a perforated lid. A Netzsch DSC 204 F1 was used for the measurement. The sample was inerted under nitrogen. It was first cooled to -150 °C, then heated to +150 °C at a rate of 10 K / min and cooled again to -150 °C. The subsequent second heating cycle was also performed at 10 K / min, and the change in heat capacity was recorded. Glass transitions are represented as steps in the thermogram (heat flow-temperature diagram, see [reference]). Fig. 1) identified.

[0117] The glass transition temperature T g is obtained as follows (see Fig. 1): The linear portions of the measurement curve before and after the step are extended in the direction of increasing (before the step) and decreasing (after the step) temperatures, respectively (extension lines ① and ②). Within the step, a regression line ⑤ is placed parallel to the ordinate such that it intersects the two extension lines, creating two areas (③ and ④) of equal area (between the respective extension lines, the regression line, and the measurement curve). The intersection of this regression line with the measurement curve yields the glass transition temperature. Method 2 - Determination of molar masses

[0118] The values ​​for weight-average molar mass M wThis document refers to the well-known determination by gel permeation chromatography (GPC). The determination is performed on 100 µl of clear filtered sample (sample concentration 3 g / l). Tetrahydrofuran is used as the eluent. The measurement is carried out at 25 °C.

[0119] A PSS-SDV type column, 5 µm, 10 is used as a pre-column. 3 Å, 8.0 mm * 50 mm (Specifications here and below in the order: type, particle size, inner diameter * length; 1 Å = 10 -10 m) is used. For separation, a combination of columns of type PSS SDV, 5 µm, 10 is used. 3 Å and 10 5 Å and 10 6 Å with 8.0 mm * 300 mm each (Agilent columns; detection using PSS SECcurity differential refractometer) 2The flow rate is 1.0 ml per minute. Calibration is performed using the commercially available Agilent ReadyCal kit for poly(styrene) high. This is universally converted to polymethyl methacrylate (PMMA) using the Mark Houwink parameters K and alpha, so that the data is given in PMMA mass equivalents.

[0120] The weight-average molecular weight M w The concentration is determined by gel permeation chromatography (GPC). THF is used as the eluent. The measurement is performed at 23 °C. PSS-SDV, 5 µm, 10⁻⁵, is used as the guard column. 3 Å, ID 8.0 mm x 50 mm is used. The columns PSS-SDV, 5 µ, 10 are used for separation. 3 Å, 104 Å, and 106 Å, each with an ID of 8.0 mm x 300 mm, were used. The sample concentration was 4 g / l, and the flow rate was 1.0 ml per minute. Calibration was performed using the commercially available ReadyCal kit Poly(styrene) high from PSS Polymer Standard Service GmbH, Mainz, Germany.

[0121] Polydispersity (PDI) is determined, as is known to those skilled in the art, as the quotient of weight-average and number-average molar mass. Method 3 - Dynamic-Mechanical Analysis (DMA)

[0122] G' and G'' are determined using a rheometer. The material under investigation is subjected to a sinusoidally oscillating shear stress in a plate-plate arrangement. In shear-stress controlled instruments, the deformation is measured as a function of time, along with the time lag of this deformation relative to the application of the shear stress. This time lag is called the phase angle δ.

[0123] The storage modulus G' is defined as follows: G' = (τ / γ) ·cos(δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between the shear stress and deformation vectors). The definition of the loss modulus G'' is: G'' = (τ / γ) ·sin(δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between the shear stress and deformation vectors). tan δ = G'' / G'. Device: MCR 302e rheometer (Anton Paar), plate-plate, ø 12 mm Deformation: Dynamic adaptation Measurement frequency: 1 Hz Measurement method: Frequency Sweep Measuring range: 10 -5 - 10 2 Hz Method 4 - Determination of static shear strength (shear life; SLS)

[0124] Shear strength is a measure of the internal strength of the adhesive and was tested in the so-called static shear test as follows: The test was performed under standard climate conditions (23 °C, 50% relative humidity; SLS (RT) 1 kg) using a 1 kg weight. A 1.3 cm wide strip of the sample (50 µm polymer layer on 36 µm etched PET film) was bonded to a polished steel plate over a length of 2 cm by rolling it with a 2 kg roller (twice in each direction). The plates were equilibrated for 30 min under test conditions but without a load. Then the test weight (1 kg) was attached, creating a shear stress parallel to the bonded area, and the time until bond failure was measured. The measurement result is given in minutes. The median of three individual measurements is reported. A shear life at room temperature of at least 10,000 min is considered a good result.

[0125] The shear life is determined under a test climate of 70 ± 1 °C and 10% ± 10% relative humidity (“SSZ (70°C) 0.5 kg”) analogously to the procedures described above, whereby the prepared plate was equilibrated for 30 minutes under the test conditions at 70 °C before a 0.5 kg weight was suspended. A shear life of at least 100 minutes at 70 °C is considered a good result for temperature stability. A shear life of at least 300 minutes at 70 °C is considered a very good result for temperature stability. Method 5 - Adhesive strength of steel

[0126] The adhesive strength was determined under a test climate of 23 °C ± 1 °C and 50% ± 5% relative humidity. The samples were cut to a width of 20 mm and adhered to a steel plate (ASTM). The steel plate was cleaned and conditioned before adhesion. For this, the plate was first wiped with solvent and then left to air dry for 5 minutes to allow the solvent to evaporate. The side of the adhesive tape facing away from the test substrate was then covered with 25 µm thick etched PET film, preventing the sample from stretching during measurement. The test sample was then rolled onto the substrate. For this, the tape was rolled back and forth five times with a 4 kg roller at a winding speed of 10 m / min. One minute after rolling, the plate was inserted into a special holder.The adhesive strength was measured using a Zwick tensile testing machine; the samples were peeled off at an angle of 180° at a speed of 300 mm / min. The measurement results are given in N / cm and are averaged from three individual measurements. An adhesive strength of at least 3 N / cm is considered a good result. Method 6 - Determination of the Tack

[0127] In this test, a 5.6 g steel ball rolled from a 65 mm high ramp (21° incline) onto a horizontal strip of the adhesive being tested. The distance the ball traveled until it came to a stop was measured (test climate 23°C, 50% relative humidity). A distance of up to 300 mm is considered a good result.

[0128] The spheres were cleaned with cellulose and acetone before measurement and conditioned in the test climate for 30 minutes.

[0129] The adhesive was conditioned in the test climate for one day before measurement. Method 7 - Determination of the Shear Adhesion Failure Temperature (SAFT)

[0130] The SAFT determination was performed as follows: A polished steel surface was used as the defined bonding surface. The bondable surface element to be tested was cut to a width of 10 mm and a length of approximately 5 cm and immediately pressed three times onto the selected bonding surface (10 x 13 mm area) using a 2 kg steel roller at a feed rate of 10 m / min. Immediately afterward, the bonded surface element was subjected to a load of 0.5 N at an angle of 180° and a temperature ramp of 9°C / min was applied. The temperature at which the sample traveled a sliding distance of 1 mm was measured. The measured value (in °C) is the average of two individual measurements. A SAFT value above 90 °C is considered a good result, and a SAFT value above 120 °C is considered a very good result. Production of polymer A

[0131] A conventional 3 L vessel for radical polymerizations was filled with 900 g of n-butyl acrylate (nBA), 3.933 g of 1,4-phenylenebis(methylene)didodecyl dicarbonotrithioate (BM1812; CAS 960256-58-0), and 900 g of ethyl acetate (EtAc). After 45 minutes of nitrogen gas purging with stirring, the reactor contents were heated to 58°C, and 0.229 g of Vazo® 67 was added. The reactor contents were then heated further to 65°C. After a reaction time of 24 hours, the reactor contents were cooled to 35°C. The conversion was >95%, and the proportion of polymer A in the polymer solution was 50 wt%.

[0132] The polymer A has a weight-average molar mass M w of 238,000 g / mol and a polydispersity PDI of 1.46. Production of polymer B

[0133] A conventional 3 L vessel for radical polymerizations was filled with 810 g of 2-ethylhexyl acrylate, 90 g of acrylic acid, 3.159 g of 1,4-phenylenebis(methylene)didodecyl dicarbonotrithioate (BM1812; CAS 960256-58-0), and 900 g of ethyl acetate (EtAc). After passing nitrogen gas through the reactor for 45 minutes while stirring, the contents were heated to 58°C and 0.092 g of Vazo® 67 was added. The reactor contents were then heated further to 65°C. After a reaction time of 24 hours, the reactor contents were cooled to 35°C. The conversion was >95%, and the proportion of polymer A in the polymer solution was 50 wt%.

[0134] Polymer B has a weight-average molar mass M w of 481,000 g / mol and a polydispersity PDI of 2.6. Production of polymer C

[0135] A conventional 3 L vessel for radical polymerizations was filled with 900 g of n-butyl acrylate (nBA), 24.516 g of 1,4-phenylenebis(methylene)didodecyl dicarbonotrithioate (BM1812; CAS 960256-58-0), and 900 g of ethyl acetate (EtAc). After passing nitrogen gas through the reactor for 45 minutes with stirring, the contents were heated to 58°C and 0.715 g of Vazo® 67 was added. The reactor contents were then heated further to 65°C. After a reaction time of 24 hours, the reactor contents were cooled to 35°C. The conversion was >95%, and the proportion of polymer A in the polymer solution was 50 wt%.

[0136] The polymer C has a weight-average molar mass M w of 37,200 g / mol and a polydispersity PDI of 1.2. Production of the block copolymer BC1

[0137] A conventional 3 L vessel for radical polymerizations was filled with 1350 g of the polymer solution of polymer A, 225 g of iso-bornyl acrylate (IBOA), and 225 g of ethyl acetate (EtAc). After passing nitrogen gas through the vessel for 45 minutes while stirring, the reactor contents were heated to 58°C, and 0.172 g of Vazo® 67 was added. The reactor contents were then heated further to 65°C. After 3 h, the mixture was diluted with 300 g of ethyl acetate, and again after 5 h with another 300 g of ethyl acetate. After a reaction time of 24 h, the reactor contents were cooled to 35°C. The conversion was >98%.

[0138] The block copolymer BC1 has a weight average molar mass M w of 706,000 g / mol and a polydispersity PDI of 10.2. Production of the block copolymer BC2

[0139] A conventional 3 L vessel for radical polymerizations was filled with 1350 g of the polymer solution of polymer A, 225 g of dicyclopentanyl acrylate (DCPA), and 225 g of ethyl acetate (EtAc). After 45 minutes of nitrogen gas purging with stirring, the reactor contents were heated to 58°C, and 0.172 g of Vazo® 67 was added. The reactor contents were then heated further to 65°C. After 3 h, the mixture was diluted with 300 g of ethyl acetate, and again after 5 h with another 300 g of ethyl acetate. After a reaction time of 24 h, the reactor contents were cooled to 35°C. The conversion was >98%.

[0140] The block copolymer BC2 has a weight-average molar mass M w of 657,000 g / mol and a polydispersity PDI of 8.2. Production of the block copolymer BC3

[0141] A conventional 3 L vessel for radical polymerizations was filled with 1417 g of the polymer solution of polymer A, 192 g of norbornyl acrylate, and 192 g of ethyl acetate (EtAc). After passing nitrogen gas through the reactor for 45 minutes while stirring, the contents were heated to 58°C and 0.181 g of Vazo® 67 was added. The reactor contents were then heated further to 65°C. After 3 h, the mixture was diluted with 300 g of ethyl acetate, and again after 5 h with another 300 g of ethyl acetate. After a reaction time of 24 h, the reactor contents were cooled to 35°C. The conversion was >98%.

[0142] The block copolymer BC3 has a weight-average molar mass M w of 696,000 g / mol and a polydispersity PDI of 7.0. Production of the block copolymer BC4

[0143] A conventional 3 L vessel for radical polymerizations was filled with 1494 g of the polymer solution of polymer B, 153 g of dicyclopentanyl acrylate (DCPA), and 153 g of ethyl acetate (EtAc). After passing nitrogen gas through the reactor for 45 minutes with stirring, the contents were heated to 58°C and 0.052 g of Vazo® 67 was added. The reactor contents were then heated further to 65°C. After 3 h, the mixture was diluted with 300 g of ethyl acetate, and again after 5 h with another 300 g of ethyl acetate. After a reaction time of 24 h, the reactor contents were cooled to 35°C. The conversion was >98%.

[0144] The block copolymer BC4 has a weight-average molar mass M w of 801,000 g / mol and a polydispersity PDI of 13.7. Production of the block copolymer BC5 (comparative example 2)

[0145] A conventional 3 L vessel for radical polymerizations was filled with 1340 g of the polymer solution of polymer C, 230 g of dicyclopentanyl acrylate (DCPA), and 230 g of ethyl acetate (EtAc). After 45 minutes of nitrogen gas purging with stirring, the reactor contents were heated to 58°C, and 0.532 g of Vazo® 67 was added. The reactor contents were then heated further to 65°C. After 5 h, the mixture was diluted with 300 g of ethyl acetate. After a reaction time of 24 h, the reactor contents were cooled to 35°C. The conversion was >98%.

[0146] The block copolymer BC5 has a weight-average molar mass M w of 52,700 g / mol and a polydispersity PDI of 1.5. Propene preparation for measurement and testing methods

[0147] Unless otherwise specified, the prepared block copolymers were coated from solution onto a siliconized release film (50 µm polyester) using a doctor blade and subsequently dried (coating speed 2.5 m / min, drying tunnel 15 m, temperatures Zone 1: 40 °C, Zone 2: 70 °C, Zone 3: 95 °C, Zone 4: 105 °C). The mass deposition after drying was 50 g / m². 2 . Table 1: Adhesive strength and shear life of the block copolymers Block copolymer Adhesive strength (ASTM; failure pattern) SSZ (RT) 1kg BC1 4.1 N / cm (adhesive failure) > 10,000 min BC2 3.8 N / cm (adhesive failure) > 10,000 min BC3 4.1 N / cm (adhesive failure) > 10,000 min BC4 4.2 N / cm (adhesive failure) > 10,000 min Comparison example 1 (Kuraray LA2330, Kuraray Co., LTD.) 1.6 N / cm (adhesive failure) > 10,000 min BC5;Comparison example 2 4.3 N / cm (cohesive failure) < 10 min

[0148] The commercially available LA2330 (Kuraray Co., LTD.; Comparative Example 1) is an n-butyl acrylate-based block copolymer which has a PMMA content of approximately 20 wt.%.

[0149] Example 2 exhibits cohesive failure in the adhesive strength measurement failure pattern. Due to insufficient cohesion, example 2 is not suitable as an adhesive compound.

[0150] For examples BC2 and BC4, the SAFT value and the shear life at 70 °C [SSZ (70°C) 0.5 kg] were determined. BC2 has a SAFT value of 173 °C and a shear life at 70 °C [SSZ (70°C) 0.5 kg] of 1801 minutes. BC4 has a SAFT value of 140 °C and a shear life at 70 °C [SSZ (70°C) 0.5 kg] of 350 minutes. QUOTES INCLUDED IN THE DESCRIPTION

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

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

[0011] Houben-Weyl, Methods of Organic Chemistry, Vol. E19a, p. 60ff

[0104]

Claims

[1] Pressure-sensitive adhesive based on at least one block copolymer BC comprising at least one polymer block P(A) and at least one polymer block P(B), wherein - P(A) independently comprising homo- or copolymer blocks comprising a total of at least 80 wt% monomers A selected from the group consisting of methacrylic esters, methacrylamides and monomers with at least one polymerizable vinyl group; - P(B) independently comprising homo- or copolymer blocks comprising a total of at least 80 wt% monomers B selected from the group consisting of methacrylic esters, methacrylamides and monomers with at least one polymerizable vinyl group; characterized by , that - the monomers A to a total of at least 50 wt% one or more acrylate monomers A1 selected from the general structure CH2=C(H)(COOR 1 ) include; where R 1Each occurrence is independently selected from a linear or branched alkyl group with 4 to 17 carbon atoms; - the monomers B to a total of at least 60 wt% one or more (meth)acrylate monomers B1 selected from the general structure CH2=C(R 2 )(COOR 3 ) include; where R 2 selected independently from H and CH3 for each occurrence; and R 3 The compound is selected independently for each occurrence from an optionally substituted, cyclic or polycyclic alkyl group with at least 6 carbon atoms. [2] Adhesive compound according to claim 1, characterized by that the monomers B1 each have a glass transition temperature of the homopolymer in question which is greater than or equal to 90°C, preferably greater than or equal to 100°C, and in particular greater than or equal to 105°C. [3] Adhesive compound according to any of the preceding claims, characterized bythat the monomers A1 each have a glass transition temperature of the homopolymer in question which is less than or equal to 0 °C, more preferably less than or equal to -10 °C, and in particular preferably less than or equal to -20 °C. [4] Adhesive compound according to any of the preceding claims, characterized by that the block copolymer BC has a weight-average molar mass M w ≥ 200,000 g / mol, preferably M w ≥ 350,000 g / mol, particularly preferred M w has a density of ≥ 500,000 g / mol. [5] Adhesive compound according to any of the preceding claims, characterized by , that the block copolymer BC has a polydispersity greater than 2. [6] Adhesive compound according to any of the preceding claims, characterized by , that the polymer blocks P(B) are present in a proportion between 5 and 49 wt.%; preferably between 7.5 and 35 wt.%; in particular between 10 and 30 wt.%; based on the total of the polymer blocks P(A) and P(B) of the block copolymer BC. [7] Adhesive compound according to any of the preceding claims, characterized by , that the block copolymer BC can be described by one or more of the following general formulas: P(A)−P(B)−P(A) P(B)−P(A)−P(B) P(B)−P(A)−P(B)−P(A)−P(B) P(A)−P(B)−P(A)−P(B)−P(A) [P(A)−P(B)]nX [P(B)−P(A)]nX [P(B)−P(A)−P(B)]nX [P(A)−P(B)−P(A)]nX [P(A)−P(B)]nX[P(B)]m [P(B)−P(A)]nX[P(A)]m where n = 2 to 12, m = 1 to 12 and X represents a di- or multifunctional branching region. [8] Adhesive compound according to any of the preceding claims, characterized by that the polymer blocks P(A) and P(B) are not homogeneously miscible with each other. [9] Adhesive compound according to any of the preceding claims, characterized by, that the monomers A1 are selected from the group consisting of n-butyl acrylate, iso-butyl acrylate, iso-amyl acrylate, n-hexyl acrylate, n-heptyl acrylate, 2-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, n-octyl acrylate, iso-octyl acrylate, n-nonyl acrylate, iso-nonyl acrylate, 2-propylheptyl acrylate, n-decyl acrylate, iso-decyl acrylate, lauryl acrylate, tetradecyl acrylates, heptadecyl acrylate. [10] Adhesive compound according to any of the preceding claims, characterized by , that the monomers B1 are selected from the general structure CH2=C(R 2 )(COOR 3 ); where R 2 equals H; and R 3 The alkyl group is selected independently for each occurrence from a cyclic or polycyclic alkyl group with 6 to 14 carbon atoms, preferably 7 to 12 carbon atoms. [11] Adhesive compound according to any of the preceding claims, characterized by that the monomers B1 are not isobornyl acrylate. [12] Adhesive compound according to any of the preceding claims, characterized by that the monomers B1 are selected from the group consisting of norbornyl acrylate, tricyclodecanol acrylate and dicyclopentanyl acrylate, preferably the monomers B1 being equal to dicyclopentanyl acrylate. [13] Adhesive compound according to any of the preceding claims, characterized by that the monomers A and monomers B contain a total of no more than 15 wt.%, preferably no more than 10 wt.%, and particularly preferably no more than 5 wt.% methyl methacrylate. [14] Adhesive compound according to any of the preceding claims, characterized by that the monomers A and / or monomers B are essentially free of methyl methacrylate; more preferably free of methacrylic acid esters and methacrylamides; in particular free of any methacrylic compounds. [15] Adhesive compound according to any of the preceding claims, comprising at least one block polymer BC to at least 50 wt.%, preferably to at least 60 wt.%, particularly preferably to 70 wt.% based on the total weight of the adhesive compound. [16] Adhesive tape comprising an adhesive compound according to any one of claims 1 to 15. [17] Method for producing an adhesive compound according to any one of claims 1 to 15 characterized by that at least one polymerization step takes place in a closed shell and / or is a RAFT polymerization.

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