Pressure-sensitive adhesive composition

Abstract

The object of this invention is to provide a pressure-sensitive adhesive composition based on at least one block copolymer, said adhesive composition having good or improved properties, particularly temperature and aging stability, and suitable for use in elevated temperature ranges. This is achieved by a pressure-sensitive adhesive composition based on at least one block copolymer BC, having at least one polymer block P(A) and at least one polymer block P(B), wherein - P(A) independently comprises homopolymer or copolymer blocks comprising a total of at least 80% by weight monomer A selected from methacrylates, methacrylamides, and monomers having at least one polymerizable vinyl group; - P(B) independently comprises homopolymer or copolymer blocks comprising a total of at least 80% by weight monomer B selected from methacrylates, methacrylamides, and monomers having at least one polymerizable vinyl group; and characterized in that - said monomer A contains a total of at least 50% by weight monomer B selected from the common structure CH2=C(H)(COOR) 1 One or more acrylate monomers A1; wherein R 1 Each time it appears, it is independently selected from straight-chain or branched hydrocarbon groups having 4 to 17 carbon atoms; and - said monomer B contains a total of at least 60% by weight of a group selected from the common structure CH2=C(R 2 (COOR 3 One or more (meth)acrylate monomers B1; wherein R 2 Each time it appears, it is independently selected from H and CH3; and R 3 Each time it appears, it is independently selected from optionally substituted cyclic or polycyclic alkyl groups having at least 6 carbon atoms.

Description

Technical Field

[0001] This invention relates to pressure-sensitive adhesive compositions based on at least one block copolymer, characterized by improved temperature stability and enhanced cohesiveness while maintaining high adhesion strength. Background Technology

[0002] The demand for stability in pressure-sensitive adhesive compositions is constantly increasing. In particular, these compositions are expected to exhibit excellent adhesive properties even at high temperatures. To meet this demand, (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, clear transparency, and inherent tackiness) with the properties of styrene block copolymers (such as thermally reversible physical crosslinking and high cohesive strength).

[0003] Disadvantages of pressure-sensitive adhesive compositions based on styrene block copolymers include: in systems using unsaturated polymer chains in the elastomeric blocks—for example, when using styrene-isoprene-styrene (SIS) and styrene-butadiene-styrene (SBS) block copolymers—these systems exhibit low resistance to aging caused by UV radiation, as well as low resistance to thermal oxidative degradation and ozone decomposition. Therefore, the advantages of clear, transparent self-adhesive tapes cannot be fully realized because the pressure-sensitive adhesive composition must be protected from light. This is achieved, for example, by using light-absorbing additives such as titanium dioxide, the incorporation of which results in opaque products. Styrene block copolymers with chemically saturated elastomeric blocks, such as hydrogenated analogs of SBS and SIS—styrene-ethylene / butene-styrene (SEBS) and styrene-ethylene / propylene-styrene (SEPS)—do exhibit significantly improved aging resistance; therefore, they generally do not require light-absorbing additives and can thus be more easily processed into clear, transparent products. However, a drawback is that a good balance between adhesive strength and low re-peel force, as known in SIS and SBS-based pressure-sensitive adhesive compositions, is often not achievable. Furthermore, the selection of sufficiently compatible adhesive resins is significantly limited compared to, for example, SIS, if plasticizers (e.g., liquid resins, aliphatic oils) are not used—which is desirable for many formulations.

[0004] However, commercially available (meth)acrylate-based block copolymers are limited by the choice of monomers that form the various polymer blocks and the resulting glass transition temperatures of those polymer blocks. Typically, commercially available block copolymers contain polymethyl methacrylate (PMMA) as a monomer for the hard (polymer) blocks (i.e., blocks with high glass transition temperatures) and exhibit heat resistance attributable to the glass transition temperature of PMMA. The limited use of monomers in commercially available block copolymers means that the desired properties cannot be fully achieved at high temperatures. 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] Various studies have been conducted on methods involving polar monomers (such as methacrylates or acrylates) in anionic polymerization. However, such polar monomers contain functional groups, such as carbonyl groups, which are sensitive to nucleophilic attack. Therefore, achieving favorable conditions for living polymerization is relatively difficult in the anionic polymerization of polar monomers because side reactions or intermolecular cyclization reactions (so-called "backbiting") occur at the growth ends of the resulting polymer. Thus, the choice of monomers is limited, which is why alternative block copolymers based on different structural units are needed. Furthermore, anionic polymerization places very high demands on reaction conditions and reaction control, as well as the purity of the reactants. Summary of the Invention

[0006] The object of the present invention is to provide a pressure-sensitive adhesive composition based on at least one block copolymer, which substantially comprises a (meth)acrylic acid derivative, exhibiting good adhesion strength, particularly on polar substrates, and good shear life.

[0007] The first and general subject of the present invention (in order to achieve these objectives) is a pressure-sensitive adhesive composition 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

[0008] - P(A) independently comprises homopolymer or copolymer blocks comprising monomer A, which comprises a total of at least 80% by weight of monomer A selected from methacrylates, methacrylamides and monomers having at least one polymerizable vinyl group; - P(B) independently comprises homopolymer or copolymer blocks comprising monomer B, which comprises a total of at least 80% by weight of monomer B selected from methacrylates, methacrylamides and monomers having at least one polymerizable vinyl group; Its features - The monomer A comprises a total of at least 50% by weight of the material selected from the common structure CH2=C(H)(COOR). 1 One or more acrylate monomers A1 (“monomer A1”); wherein R1 Each time it appears, it is independently selected from straight-chain or branched alkyl groups having 4 to 17 carbon atoms; - The monomer B comprises a total of at least 60% by weight of the material selected from the common structure CH2=C(R) 2 (COOR) 3 One or more (meth)acrylate monomers B1 (“monomer B1”); wherein R 2 Each time it appears, it is independently selected from H and CH3; and R 3 Each time it appears, it is independently selected from optionally substituted cyclic or polycyclic alkyl groups having at least 6 carbon atoms, preferably 6 to 14 carbon atoms.

[0009] In one embodiment, the pressure-sensitive adhesive composition is suitable for use at elevated temperatures, particularly in a temperature range up to 70°C.

[0010] Details and embodiments of the invention are described below. The preferred embodiments, referred to in any form below, are combinations of features of particularly preferred embodiments with features of other embodiments, referred to in any form below as preferred. Therefore, combinations of two or more embodiments, referred to in any form below as “particularly preferred,” are highly particularly preferred. Also preferred are embodiments in which features of embodiments described to any degree as “preferred” are combined with one or more further features of other embodiments described to any degree as “preferred.”

[0011] When a specific quantity or proportion of an element and a preferred embodiment of that element are disclosed below, the specific quantity or proportion of the preferred embodiment is also specifically disclosed. Furthermore, it is disclosed that for a corresponding specific total quantity or proportion of an element, at least some elements may be in a preferred configuration, and in particular, the elements in the preferred configuration may exist within a specific total quantity or proportion.

[0012] As understood by those skilled in the art, pressure-sensitive adhesive compositions are adhesive compositions with pressure-sensitive properties, meaning they form a permanent bond with a substrate even under relatively light pressure. Such adhesive compositions or pressure-sensitive tapes are typically also permanently self-adhesive at room temperature, meaning they exhibit a certain viscosity and initial tack, allowing them to wet the substrate surface even under light pressure. Without wishing to be bound by this theory, it is generally assumed that pressure-sensitive adhesive compositions can be considered as extremely viscous liquids with elastic components, thus exhibiting the characteristic viscoelastic properties that lead to the aforementioned permanent self-adhesion and pressure-sensitive bonding properties. It is assumed that in pressure-sensitive adhesive compositions, mechanical deformation causes the viscous flow process and the construction of elastic restoring forces. The viscous flow component is used to achieve adhesion, while the elastic restoring force is specifically used to achieve cohesion. The relationship between rheology and pressure-sensitive adhesion is known in the prior art and is described, for example, in Satas, *Handbook of Pressure-Sensitive Adhesives*, 3rd edition (1999), pp. 153–203. To characterize the degree of elasticity and viscous components, storage modulus (G') and loss modulus (G'') are typically used; these can be determined by dynamic mechanical analysis (DMA), for example using a rheometer. In the context of this invention, if at a temperature of 23°C and 10 0 Up to 10 1 Within the rad / sec deformation frequency range, G' and G'' are each at least partially at 10 3 Up to 10 7 Within the range of Pa, the adhesive composition is preferably understood to be viscous and therefore a pressure-sensitive adhesive composition.

[0013] Block copolymers are macromolecules composed of two or more covalently linked polymer blocks, such as polymer block A "P(A)" and polymer block B "P(B)". Adjacent polymer blocks are composed of structural units derived from different monomer species, or from the same monomer species but with different compositions or structural unit sequence distributions. The specific molecular structure of the blocks often leads to microphase separation, and thus the formation of nanoscale morphologies.

[0014] The block copolymer of the present invention is a polymer system. As used in this invention, the term "polymer system" refers to both a single polymer and a mixture of two or more different polymers. According to the art, the term "polymer" or "single polymer" is understood to mean not only a single macromolecule, but also a multitude of macromolecules derived from the same polymerization process and exhibiting a specific molecular weight distribution among them.

[0015] The pressure-sensitive adhesive composition of the present invention is based on at least one block copolymer BC. In this context, "based on" or "with regard to" or "based on" means that the properties of the pressure-sensitive adhesive composition are at least largely determined by the fundamental properties of the at least one block copolymer BC, although these properties may be further influenced by the use of modifying agents or additives in the composition. In particular, this may mean that the at least one block copolymer BC constitutes more than 50% by weight of the total mass of the pressure-sensitive adhesive composition.

[0016] In one embodiment, the pressure-sensitive adhesive composition of the present invention comprises at least one block copolymer BC in an amount of at least 50% by weight, preferably at least 60% by weight, and most preferably 70% by weight relative to the total weight of the pressure-sensitive adhesive composition.

[0017] The block copolymer BC comprises at least one polymer block P(A) and at least one polymer block P(B). Each polymer block P(A) independently represents a homopolymer or copolymer block of monomer A in each occurrence. Each polymer block P(B) independently represents a homopolymer or copolymer block of monomer B in each occurrence.

[0018] Polymer block P(A), as described in the main claim or preferred embodiment, can be a polymer chain of a single type of monomer A or a copolymer of monomer A with different structures. In particular, the monomer A used has different chemical structures and / or different alkyl lengths. Polymer blocks thus span a range from completely homogeneous polymers, polymers of monomers with the same basic chemical structure but different chain lengths, and polymers of monomers with the same number of carbons but different isomers, to statistically polymeric blocks of monomers with different isomers from group A with different lengths. This also applies to polymer block P(B) with respect to monomer B, which may, for example, differ in its cyclic or polycyclic alkyl units.

[0019] An advantageous embodiment is wherein the block copolymer has a symmetrical structure, such that there are polymer blocks P(A) and / or polymer blocks P(B) with the same chain length and / or chemical structure.

[0020] However, this also includes all “asymmetric” structures in which all polymer blocks P(A) and P(B) satisfy the above criteria, but chemical or structural identity of individual structural units is not required.

[0021] The block copolymer of the present invention exists in at least two phases, comprising at least one polymer block P(A) and at least one polymer block P(B). Each time a polymer block P(A) appears, it independently represents a homopolymer or copolymer block of monomer A, wherein monomer A comprises one or more monomers selected from methacrylates, methacrylamide, and monomers having at least one polymerizable vinyl group. Each time a polymer block P(B) appears, it independently represents a homopolymer or copolymer block of monomer B, wherein monomer B comprises one or more monomers selected from methacrylates, methacrylamide, and monomers having at least one polymerizable vinyl group.

[0022] Monomer A comprises one or more monomers selected from methacrylates, methacrylamides, and monomers having at least one polymerizable vinyl group in an amount of at least 80% by weight, alternatively 85% by weight, more preferably at least 90% by weight, particularly preferably at least 95% by weight, and especially at least 98% by weight. Very particularly preferably, monomer A comprises only one or more monomers selected from methacrylates, methacrylamides, and monomers having at least one polymerizable vinyl group.

[0023] The monomer A of the present invention comprises at least 50% by weight, based on the total weight of monomer A, one or more of the common structure CH2=C(H)(COOR) 1 ) of acrylate monomer A1; wherein R 1 Each time it appears, it is independently selected from straight-chain or branched alkyl groups having 4 to 17 carbon atoms.

[0024] In a further embodiment, the monomer A of the present invention comprises one or more monomers A1 in total at least 75% by weight, at least 85% by weight, at least 90% by weight, at least 95% by weight, at least 98% by weight, or 100% by weight relative to the total weight of monomer A.

[0025] In one embodiment, monomer A1 is selected from n-butyl acrylate, isobutyl acrylate, isoamyl acrylate, n-hexyl acrylate, n-heptyl acrylate, 2-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, isononyl acrylate, 2-propylheptyl acrylate, n-decyl acrylate, isodecyl acrylate, lauryl acrylate, tetradecyl acrylate, and heptadecanyl acrylate.

[0026] Monomer B comprises one or more monomers selected from methacrylates, methacrylamides, and monomers having at least one polymerizable vinyl group in an amount of at least 80% by weight, alternatively 85% by weight, more preferably at least 90% by weight, particularly preferably at least 95% by weight, and especially at least 98% by weight. Very particularly preferably, monomer B comprises only one or more monomers selected from methacrylates, methacrylamides, and monomers having at least one polymerizable vinyl group.

[0027] The monomer B of the present invention comprises at least 60% by weight of one or more components selected from the common structure CH2=C(R) 2 (COOR) 3 (Meth)acrylate monomer B1; wherein R 2 Each time it appears, it is independently selected from H and CH3; and R 3 Each time it appears, it is independently selected from optionally substituted cyclic or polycyclic alkyl groups having at least 6 carbon atoms, preferably 6 to 14 carbon atoms. Thus, one or more (meth)acrylate monomers B1 have the characteristic of R 3 Cyclic alkyl groups (optionally with additional substituents) or polycyclic alkyl groups (optionally with additional substituents).

[0028] Polycyclic R 3 Examples include bridged cycloalkyl groups, such as norbornyl or isobornyl, but also bicyclic and polycyclic groups, such as adamantyl, tricyclic decyl, or dicyclopentyl. In this document, information regarding the number of carbon atoms in a substituent refers to the total number of carbon atoms present in the substituent, including any optional additional 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 dicyclopentyl is a polycyclic group with 10 carbon atoms. Where norbornyl is exemplary substituted with a CN group, that group will be designated as a cyclic group with 8 carbon atoms.

[0029] R 3 Optionally, it may contain one or more substituents. For example, the optional substituents are independently selected from CN and halogens in each case. Preferably, the substituent R 3 It has a cyclic or polycyclic basic structure containing additional alkyl groups, preferably C1-C6 alkyl groups, particularly preferably methyl or ethyl, and very particularly preferably methyl. For example, isobornyl (C10) has the cyclic basic structure of norbornyl (C7) containing three additional methyl groups (3x C1).

[0030] In a further embodiment, the monomer B of the present invention comprises one or more monomers B1 in total at least 75% by weight, at least 85% by weight, at least 90% by weight, at least 95% by weight, at least 98% by weight, or 100% by weight relative to the total weight of monomer B.

[0031] In one embodiment, monomer B1 is selected from cyclohexyl acrylate, tert-butylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, cyclohexyl methacrylate, 2-acryloyloxy-2-methyladamantane, norbornyl acrylate, dicyclopentyl acrylate, tricyclodecyl acrylate, and isobornyl acrylate.

[0032] In one embodiment, monomer B of the present invention comprises at least 60% by weight of one or more components selected from the common structure CH2=C(R) 2 (COOR) 3 (Meth)acrylate monomer B1; wherein R 2 For H; and R 3 Each time it appears, it is independently selected from optionally substituted cyclic or polycyclic alkyl groups having at least 6 carbon atoms.

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

[0034] In a particularly preferred embodiment, monomer B1 is selected from the general structure CH2=C(H)(COOR). 3 ); where R 3 Each time it appears, it is independently selected from cyclic or polycyclic alkyl groups having a basic structure containing at least 6 carbon atoms and optionally containing one or more methyl substituents, wherein R 3 It contains a total of 6 to 14, preferably 7 to 12, carbon atoms.

[0035] Surprisingly, good adhesive strength and shear lifetime were observed in acrylate compounds as monomer B1, which were previously achieved only with methacrylate compounds or styrene. Furthermore, acrylate compounds are characterized by their good commercial availability.

[0036] In one implementation, R 3 It is a cyclic or polycyclic alkyl group having 6 to 14 carbon atoms, preferably 7 to 12 carbon atoms.

[0037] In one implementation, R 3 It is a polycyclic alkyl group having at least 7 carbon atoms.

[0038] In one implementation, R 3 It is a bicyclic or tricyclic alkyl group having at least 7 carbon atoms.

[0039] In a preferred embodiment, monomer B1 is selected from norborneol acrylate, tricyclodecyl acrylate, and dicyclopentyl acrylate.

[0040] In one implementation, R 3 It is a tricyclic alkyl group with 10 carbon atoms.

[0041] In a preferred embodiment, R 3 It is a dicyclopentyl substituent.

[0042] In a particularly preferred embodiment, monomer B1 is dicyclopentyl acrylate.

[0043] In one embodiment, the block copolymer contains less than 17% by weight of isoborneol acrylate.

[0044] In a preferred embodiment, monomer B1 is not isoborneol acrylate. Allergic contact dermatitis has been observed in adhesive compositions containing isoborneol acrylate when applied to the skin and in applications near the body (such as watches / smartwatches).

[0045] The block copolymers of the present invention are preferably polymer systems existing in at least two phases. Those skilled in the art will understand that this means one phase is rich in, or substantially composed of, one component of the block copolymer, such as polymer block P(A), and the other phase is rich in, or substantially composed of, another component, such as polymer block P(B). The presence of one component in a small amount in the other component, which does not prevent the formation of a multiphase structure, is considered negligible. If the block copolymers of the present invention have more than two phases, the foregoing applies accordingly to all of these phases.

[0046] Phase separation is particularly preferably achieved in such a manner that discrete regions (“domains”) – rich in polymer blocks P(A) or P(B), i.e., substantially formed by polymer blocks P(A) or P(B) – exist within a continuous matrix rich in the corresponding other polymer block, i.e., substantially formed by the corresponding other polymer block. The block copolymer according to the invention is considered to exist, in particular, in at least two phases, if at least one of the criteria a)–c) listed below is satisfied: a) Phase boundaries can be identified in high-profile analysis or Young's modulus analysis of atomic force microscopy (AFM) images of block copolymers.

[0047] b) At least two independent glass transition temperatures are obtained by differential scanning calorimetry (DSC) measurements of the block copolymer.

[0048] c) At least two tan δ maximum values ​​are obtained by dynamic mechanical analysis (DMA) of the block copolymer.

[0049] According to the present invention, the block copolymer BC existing in at least two phases also includes a microphase-separated block copolymer, i.e., a polymer system in which the discontinuous phase exists in a micro-fine distribution.

[0050] In one embodiment, the pressure-sensitive adhesive composition of the present invention is based on at least one block polymer BC existing in at least two phases.

[0051] The method of this invention aims to produce polymer systems comprising at least two phases. Furthermore, an object of this invention is to provide two-phase or multiphase polymer systems with the highest possible cohesive strength. Therefore, it seems important to consider these, as well as (if applicable), other properties of the final polymer system, when selecting the monomers used in the two polymerization steps.

[0052] Monomers having a glass transition temperature ≤ 0°C, more preferably ≤ -10°C, and especially ≤ -20°C for the corresponding homopolymer, i.e., monomers particularly suitable for polymer block P(A), such as those selected from ethyl acrylate, n-butyl acrylate, isobutyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-heptyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, isononyl acrylate, 2-propylheptyl acrylate, n-decyl acrylate, isodecyl acrylate, lauryl acrylate, 2-[[(butamino)carbonyl]oxy]ethyl acrylate, 2-cyanoethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, phenoxyethyl acrylate, isostearyl acrylate, docosyl acrylate, and 2-[2-(2-methoxyethoxy)ethoxy]ethyl acrylate.

[0053] Monomers having a glass transition temperature ≥ 50°C, more preferably ≥ 75°C, and particularly ≥ 100°C for the corresponding homopolymer, i.e., monomers particularly suitable for polymer block P(B), such as those selected from dicyclopentyl acrylate, isobornyl acrylate, norbornyl acrylate, benzyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, cyclohexyl acrylate, 4-[(6-acryloyloxy)hexyl]oxy-4'-cyanobiphenyl, N-succinimide acrylate, 1-ethylcyclopentyl acrylate, N-tert-octylacrylamide, N-tert-butylacrylamide, dimethylacrylamide, diethylacrylamide, acrylamide, N- [3-(dimethylamino)propyl]acrylamide, diacetone acrylamide, 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, glyceryl methacrylate formaldehyde, 2-dimethylaminoethyl methacrylate, phenoxyethyl methacrylate, 9-anthrayl methyl methacrylate, methyl 2-Ethyl-2-adamantane acrylate, 2-(acetylacetoxy)ethyl methacrylate, 2-isopropyl-2-methacryloyloxyadamantane methacrylate, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, furfuryl methacrylate, 2-methacryloyloxy-2-methyladamantane methacrylate, phenyl methacrylate, N-succinimide methacrylate, 2-(tert-butylamino)ethyl methacrylate, 2-cyclohexylpropyl-2-yl methacrylate, methacrylate 1-Adamantane ester, 1-methylcyclopentyl methacrylate, 3-dimethylaminopropyl methacrylamide, N-tert-butylmethacrylamide, N-(methoxymethyl)methacrylamide, N,N-dimethylmethacrylamide, methacrylamide, N-phenylmethacrylamide, N,N-dimethylmethacrylamide, N-vinylformamide, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylcarbazole, N-vinylimidazolazole, vinylmethyloxazolidinone, and N-vinyl-N-methylacetamide.

[0054] In this context, in one embodiment of the invention, monomer A comprises at least 50% by weight, more preferably at least 60% by weight, even more preferably at least 60% by weight, and particularly at least 75% by weight of one or more monomers having a glass transition temperature ≤ 0°C, more preferably ≤ -10°C, and particularly ≤ -20°C of the corresponding homopolymer; and monomer B comprises at least 60% by weight, more preferably at least 70% by weight, and particularly at least 80% by weight of one or more monomers having a glass transition temperature ≥ 50°C, more preferably ≥ 75°C, and particularly ≥ 100°C of the corresponding homopolymer, wherein—unless otherwise stated—the glass transition temperature is determined using method 1 (see the Measurement and Testing Methods section).

[0055] In one development of this embodiment, monomer A preferably comprises at least 50% by weight, more preferably at least 60% by weight, and particularly at least 75% by weight of one or more monomers A1, and monomer B comprises at least 60% by weight, more preferably at least 70% by weight, and particularly at least 80% by weight of one or more monomers B1.

[0056] More preferably, monomer A comprises a total of at least 50% by weight, more preferably at least 60% by weight, and particularly at least 75% by weight, one or more monomers selected from n-butyl acrylate, isoamyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, isooctyl acrylate, n-octyl acrylate, 2-propylheptyl acrylate, n-decyl acrylate, and isodecyl acrylate; and monomer B comprises a total of at least 60% by weight, more preferably at least 70% by weight, and particularly at least 80% by weight, one or more monomers selected from 3,3,5-trimethylcyclohexyl acrylate, dicyclopentyl acrylate, isobornyl acrylate, tricyclodecyl acrylate, and norbornyl acrylate.

[0057] In yet another development of this embodiment, monomer A preferably comprises at least 50% by weight, more preferably at least 60% by weight, and particularly at least 75% by weight of one or more monomers A1, at most 35% by weight, more preferably at most 25% by weight, and particularly at most 20% by weight of one or more monomers selected from dicyclopentyl acrylate, tricyclodecyl acrylate, isoborneol acrylate, norborneol acrylate, methyl methacrylate, dimethacrylamide, diethylacrylamide, 4-tert-butylcyclohexyl acrylate, tert-butyl acrylate, tert-butyl methacrylate, cyclohexyl methacrylate, and cyclohexyl acrylate, and at most 10% by weight of one or more functionalized monomers; and monomer B comprises at least 60% by weight, more preferably at least 70% by weight, and particularly at least 80% by weight of one or more monomers B1; and at most 10% by weight of one or more functionalized monomers, wherein the functionalized monomers are selected from hydroxyethyl acrylate, ... Propyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, 4-hydroxyethylacrylamide, acrylic acid, methacrylic acid, 2-acryloyloxyethyl succinate acrylate, methacryloyloxyethyl 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, ethyl isocyanate acrylate, ethyl isocyanate methacrylate, 2-[2-(methacryloyloxy)ethoxy]ethyl isocyanate, 2-[2-(acryloyloxy)ethoxy]ethyl isocyanate and α,α-dimethyl-m-isopropenyl benzyl isocyanate.

[0058] Specifically, monomer A comprises at least 50% by weight, more preferably at least 60% by weight, and particularly at least 75% by weight, one or more monomers selected from n-butyl acrylate, isoamyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, isooctyl acrylate, n-octyl acrylate, 2-propylheptyl acrylate, n-decyl acrylate, and isodecyl acrylate; at most 35% by weight, more preferably at most 25% by weight, and particularly at most 20% by weight, one or more monomers selected from dicyclopentyl acrylate, isoborneol acrylate, norborneol acrylate, methyl methacrylate, and dimethacrylamide; and at most 10% by weight, one or more monomers selected from acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, and 4-hydroxyethyl acrylate. Monomer B comprises monomers selected from dicyclopentyl acrylate, isoborneol acrylate, and norborneol acrylate, totaling at least 60% by weight, more preferably at least 70% by weight, and particularly at least 80% by weight; and at most 10% by weight of monomers selected from acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 3,4-epoxycyclohexyl acrylate, 3,4-epoxycyclohexyl acrylate, glycidyl acrylate, and glycidyl methacrylate.

[0059] In one embodiment, monomer A and monomer B contain a total of up to 15% by weight, preferably up to 10% by weight, and most preferably up to 5% by weight of methyl methacrylate.

[0060] In yet another development of this embodiment, at least monomer B is substantially free of methyl methacrylate; more preferably, it is free of methyl methacrylate and methacrylamide; in particular, it is free of any methacrylic acid compounds.

[0061] Preferably, monomer A is substantially free of methyl methacrylate; more preferably, it is free of methyl methacrylate and methacrylamide; in particular, it is free of any methacrylic acid compounds.

[0062] In yet another development of these embodiments, monomers A and B are substantially free of methyl methacrylate; more preferably, they are free of methyl methacrylate and methacrylamide; in particular, they are free of any methacrylic acid compounds.

[0063] Essentially free of methyl methacrylate means that the monomers (A and / or B) contain less than 1% by weight, preferably less than 0.5% by weight, of methyl methacrylate relative to the total composition, and particularly preferably free of methyl methacrylate.

[0064] It has been shown that excluding the above compounds has a beneficial effect on the polymerization rate.

[0065] 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, optimal value M w ≥ 500,000 g / mol.

[0066] In one embodiment, the block copolymer BC has a polydispersity PD greater than 2, or alternatively greater than 4 or greater than 6.

[0067] In one embodiment, at least one polymer block P(A) and / or at least one polymer block P(B) has a weight-average molecular weight M. w ≥ 100,000 g / mol, preferably M w ≥ 150,000 g / mol, more preferably M w ≥ 200,000 g / mol.

[0068] In one embodiment, the block copolymer BC exists as a multimodal block copolymer. A multimodal block copolymer is understood to be a block copolymer having at least a bimodal mass distribution, i.e., a molecular weight distribution having at least two maximum values.

[0069] In one embodiment, the block copolymer BC comprises polymeric blocks P(B) in a proportion of 5 to 49% by weight; preferably 7.5 to 35% by weight; particularly 10 to 30% by weight; based on the total amount of polymeric blocks P(A) and P(B) in the block copolymer BC.

[0070] The ratio of the chain length of block copolymer P(A) to that of block copolymer P(B) is chosen in a highly advantageous manner such that block copolymer P(B) exists as a dispersed phase (“domain”) within a continuous matrix of polymeric block P(A). This is preferably the case when the content of polymeric block P(B) is less than about 25% by weight. Within the scope of the teachings of this invention, it is also possible to form hexagonal stacked cylindrical domains of polymeric block P(B); however, this is generally not particularly preferred due to the less favorable tensile / elongation properties of the respective materials and the structural anisotropy of the resulting pressure-sensitive adhesive composition caused by the domain structure. By asymmetrically designing triblock copolymers, in which the block lengths of the terminal polymeric blocks P(B) differ in a linear system, the content of polymeric block P(B) (at which the system still forms a spherical morphology) can be increased to about 30% by weight or more. This is particularly preferred when it is necessary to improve the internal strength of the pressure-sensitive adhesive composition, and for improving mechanical properties.

[0071] 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) (Ia), - P(B)-P(A)-P(B) (Ib), - P(B)-P(A)-P(B)-P(A)-P(B) (IIa), - P(A)-P(B)-P(A)-P(B)-P(A) (IIb), - [P(A)-P(B)] n X (IIIa), - [P(B)-P(A)] n X (IIIb), - [P(B)-P(A)-P(B)] n X (IVa), - [P(A)-P(B)-P(A)] n X (IVb), - [P(A)-P(B)] n X[P(B)] m (Va), - [P(B)-P(A)] n X[P(A)] m (Vb), Where n = 2 to 12, m = 1 to 12, and X represents a bifunctional or multifunctional branched region.

[0072] Polymer block P(A), as described in the main claim or preferred embodiment, can be a polymer chain of a single type of monomer A or a copolymer of monomer A with different structures. Specifically, the monomer A used has different chemical structures and / or different side chain lengths. Polymer blocks thus span a range from completely homogeneous polymers, polymers of monomers with the same basic chemical structure but different chain lengths, and polymers of monomers with the same number of carbons but different isomers, to statistically polymeric blocks of monomers with different isomers from group A of different lengths. This also applies to polymer block P(B) with respect to monomers from group B.

[0073] Unit P(A)-P(B)-P(A) can be symmetric [corresponding to P] 1 (A)-P(B)-P 2 (A), where P 1 (A) = P 2 (A)] or asymmetric [for example, corresponding to equation P] 3 (A)-P(B)-P 4 (A), where P 3 (A) ≠ P 4 (A), but P is among them 3 (A) and P 4 (A) are all polymer blocks as defined by P(A).

[0074] An advantageous embodiment is that at least one, preferably several or all, of the block copolymers has a symmetrical structure, such that there are polymer blocks P(A) and / or polymer blocks P(B) with the same chain length and / or chemical structure. In particular, P... 3 (A) and P 4 (A) may differ in their chemical composition and / or chain length.

[0075] In a preferred embodiment, at least one block copolymer BC, preferably several or all block copolymers BC, includes at least one, and particularly preferably two, terminal groups P(B).

[0076] For an advantageous further development of the invention, an adhesive resin may be added to the pressure-sensitive adhesive composition comprising the block copolymer. In principle, any resin dissolved in the corresponding polymer block P(A) may be used. Suitable adhesive resins include, among others, rosin and rosin derivatives (rosin esters, including rosin derivatives stabilized, for example, by disproportionation or hydrogenation), polyterpene resins, terpene phenol resins, alkylphenol resins, aliphatic, aromatic, and aliphatic-aromatic hydrocarbon resins, to name just a few. Preferably, the resin is compatible with the polymer block (A). The weight fraction of the resin in the block copolymer is typically at most 40% by weight, more preferably at most 30% by weight. For specific embodiments of the invention, a resin compatible with the polymer block P(B) may also be used.

[0077] In addition, optionally, plasticizers, fillers (e.g., fibers, carbon black, zinc oxide, titanium dioxide, chalk, solid or hollow glass beads, microspheres made of other materials, silica, silicates), nucleating agents, foaming agents, compounding agents and / or anti-aging agents may be present, for example in the form of primary and secondary antioxidants or in the form of light stabilizers.

[0078] Preferably, the internal strength (cohesion) of the pressure-sensitive adhesive composition is generated by the physical crosslinking of the polymer block P(B). The resulting physical crosslinking is typically thermally reversible. For irreversible crosslinking, the pressure-sensitive adhesive composition may be additionally chemically crosslinked. For this purpose, pressure-sensitive adhesive compositions containing acrylate block copolymers may optionally contain a compatible crosslinking agent. Suitable crosslinking agents include, for example, metal chelates, polyfunctional isocyanates, polyfunctional amines, or polyfunctional alcohols. Polyfunctional acrylates can also be advantageously used as crosslinking agents for photochemical radiation.

[0079] In a further embodiment of the pressure-sensitive adhesive composition of the present invention, the polymer blocks P(A) and / or P(B) are functionalized in such a way that thermally initiated crosslinking is possible. Suitable crosslinking agents include, to name a few, epoxides, aziridines, isocyanates, polycarbodiimides, and metal chelates.

[0080] For optional crosslinking with UV light, a UV-absorbing photoinitiator is added to the polyacrylate-containing block copolymer used in the system of the present invention. Very effective and useful photoinitiators include benzoin ethers, such as benzoin methyl ether and benzoin isopropyl ether; substituted acetophenones, such as 2,2-diethoxyacetophenone (available from Ciba Geigy® as Irgacure 651®); 2,2-dimethoxy-2-phenyl-1-phenylacetophenone, dimethoxyhydroxyacetophenone, substituted α-ketones, such as 2-methoxy-2-hydroxyacetophenone, aromatic sulfonyl chlorides, such as 2-naphthylsulfonyl chloride, and photoactive oximes, such as 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime.

[0081] In an alternative embodiment, the pressure-sensitive adhesive composition of the present invention does not contain a crosslinking agent.

[0082] In a preferred embodiment, the pressure-sensitive adhesive composition of the present invention exhibits an adhesion strength (determined according to method 5) of at least 3 N / cm on steel.

[0083] In a preferred embodiment, the pressure-sensitive adhesive composition of the present invention has a SAFT value of at least 90°C, preferably at least 120°C, as determined according to method 7.

[0084] In a preferred embodiment, the pressure-sensitive adhesive composition of the present invention has a shear life of at least 10,000 minutes at room temperature as determined according to method 4.

[0085] In a particularly preferred embodiment, the pressure-sensitive adhesive composition of the present invention has a shear life of at least 100 minutes, preferably at least 300 minutes, at 70°C as determined according to method 4.

[0086] A particularly preferred embodiment of the pressure-sensitive adhesive composition of the present invention exhibits an adhesion strength on steel (determined according to method 5) of at least 3 N / cm; a SAFT value of at least 90°C, preferably at least 120°C, determined according to method 7; a shear life of at least 10,000 minutes at room temperature, determined according to method 4; and a shear life of at least 100 minutes, preferably at least 300 minutes, determined according to method 4 at 70°C.

[0087] A further subject of the invention is a method for producing an adhesive composition based on at least one block copolymer BC according to the invention, characterized in that at least one polymerization step occurs in a closed shell and / or at least one polymerization step is RAFT polymerization.

[0088] In principle, any controlled or living polymerization method can be used to produce the block copolymer BC for the pressure-sensitive adhesive compositions of the present invention, as well as combinations of various controlled polymerization methods. In this context, by way of example and not exhaustive, in addition to anionic polymerization, ATRP, nitroxide / TEMPO controlled polymerization, or more preferably, RAFT methods may be mentioned; that is, particularly those methods that allow control over block length, polymer structure, or also (but not necessarily) stereoregularity of polymer chains.

[0089] In one embodiment, the block copolymer BC is produced in two polymerization steps, the first of which occurs in the presence of a RAFT initiator.

[0090] A method for producing at least one block copolymer BC includes the following steps: a) Polymer blocks formed by polymerization of monomer A to form polymer block P(A) or by polymerization of monomer B to form polymer block P(B); and b) To form a block copolymer comprising at least two phases by polymerizing polymer blocks from the polymer blocks of step a) to form polymer blocks P(A) formed by polymerization of monomer A or polymer blocks P(B) formed by polymerization of monomer B. Monomer A and monomer B are each used in one of polymerization steps a) or b), and preferably in step a) the RAFT initiator is used. In one development scheme, at least one polymerization step occurs in a closed shell.

[0091] The RAFT polymerization in step a) can, in principle, be carried out in any manner. For example, it can be carried out in a solvent, particularly in a solvent within a conventional reactor designed for such polymerization.

[0092] The RAFT polymerization in step b) can, in principle, be carried out in any manner. For example, it can be carried out in a solvent, particularly in a solvent within a conventional reactor designed for such polymerization.

[0093] In one embodiment, the polymerization of step a) occurs in a reactor, particularly in a reactor designed for processing high-viscosity material agglomerates, or in a closed shell; more preferably, it occurs in a planetary mixer or in a closed shell.

[0094] It is also preferred that the polymerization in step a) occurs in the absence of solvent. Trace solvent concentrations, such as those caused by production residues or within the background concentration range, are considered negligible.

[0095] "RAFT polymerization" stands for "Reversible Addition-Fragmentation Chain Transfer Polymerization." This refers to a polymerization method in which the reaction is controlled via a reversible chain transfer reaction. In this method, an active growing radical chain adds to a specific controller substance, the so-called RAFT reagent, which is already linked to another chain and thus exists as a higher molecular weight RAFT reagent (macromolecule RAFT reagent). The addition of the active radical chain produces an intermediate that, due to its structure, has the potential to break in various directions. This process again produces a macromolecule RAFT reagent and radical chains that can be used for growth, where the latter does not necessarily correspond to the previous active radical chain. Thus, the probability of growth is evenly distributed across all chains, typically resulting in a narrow molecular weight distribution.

[0096] In a preferred embodiment, the polymerization in steps a) and b) is controlled radical polymerization, particularly RAFT polymerization.

[0097] According to the foregoing, at least one, preferably all, of the polymerization steps are carried out in the presence of at least one control agent containing at least one sequence -SC(=X)-, where X represents S, O or NR', and R' represents an organic group.

[0098] The control agent substance containing at least one sequence -SC(=X)- is preferably selected from the following: Dithioesters, namely compounds with the general structure (1). (1); Dithiocarbonates, namely compounds with the general structure (2). (2); Xanthates, namely compounds with the general structure (3) (3); Dithiocarbamates, namely compounds with the general structure (4). (4); Trithiocarbonates, namely compounds with the general structure (5). (5); and Imino-dithio-carbonates, namely compounds with the general structure (6). (6), In the general structures (1) to (6), each substituent R independently represents an organic or inorganic group, preferably an organic group. In particular, at least one substituent R in the general structures (1) to (6) is included in the polymer chain formed during polymerization in the relevant step.

[0099] Particularly preferred are control agents containing at least one sequence -SC(=X)- selected from trithiocarbonates and xanthates; therefore, in the sense described above, compounds derived from the general structures (3) and (5) are preferred.

[0100] Particularly preferred is that the control agent substance in its original state contains at least one sequence -SC(X)-, i.e., not yet incorporated into the growing polymer chain, selected from dibenzyl trithiocarbonate, O-ethyl-S-(1-methoxycarbonyl)ethyl xanthate, 1,4-phenylene bis(methylene)didodecyl tricarbonotrithioate, 2,2'-[carbonthioyl bis(thio)]bis[2-methylpropionic acid] and 4-cyano-4-(((dodecylthio)carbonthioyl)thio)valerate.

[0101] For an advantageous further development according to the invention, an initiator system, particularly an azo or peroxide initiator that thermally decomposes to form free radicals, can also be used in the preparation method. However, in principle, all conventional initiators known for use with acrylates are suitable for this purpose. The generation of C-centered free radicals is described in Houben-Weyl, *Organic Chemical Methods*, Vol. E19a, pp. 60 and onwards. These methods are preferred. Examples of free radical sources include peroxides, hydroperoxides, and azo compounds. Some typical examples of free radical initiators are listed here (non-exhaustive list): potassium persulfate, benzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, cyclohexylsulfonylacetyl peroxide, di-tert-butyl peroxide, azobisisobutyronitrile, diisopropyl peroxide dicarbonate, tert-butyl peroctanoate, and benzylpinacol. In a highly preferred variant, 1,1'-azo-bis-(cyclohexyl nitrile) (Vazo 88®, DuPont®) or 2,2-azo-bis-(2-methylbutyronitrile) (Vazo67®, DuPont®) is used as the radical initiator. Additionally, photoinitiators can also be used as radical sources. A "photoinitiator" is understood to be a substance that, under the influence of light of certain wavelengths, typically at least under UV radiation, and optionally also under UV radiation in the visible light wavelength range (approximately 300–500 nm), forms radical species. At least one radical-forming photoinitiator is preferably selected from 1-hydroxycyclohexylphenyl ketone and 2,2-dimethoxy-2-acetophenone.

[0102] To produce adhesive compositions, particularly pressure-sensitive adhesive compositions, by extrusion, the polymer system of the present invention (which optionally exists within a closed shell) is heated in an extruder to a temperature at which the shell material melts and can thus be uniformly incorporated into the polymer system. It has been shown that the effect of the coating material on the properties of adhesive compositions produced using the polymer system of the present invention is below a technically relevant threshold. The polymer system is heated to such an extent that it becomes deformable, particularly flowable. It has been found that the specific polymer systems of the present invention generally exhibit lower viscosity than polymers conventionally used for the production of pressure-sensitive adhesive compositions, and therefore better deformability and flowability. Thus, the polymer system of the present invention can be processed in an extruder under the influence of heat and shear, and, if desired, incorporated with other components to form an adhesive compound, and ultimately molded. The temperatures typically used in this process do not cause the decomposition of the control agents incorporated into the polymer framework (main chain), and therefore do not lead to polymer degradation. A key advantage of the present invention is that solvent removal is not required before processing the polymer system in the extruder, a step that often leads to the degradation processes just described.

[0103] Further processing steps, such as mixing with additives, filtering, or degassing, can also be carried out in an extruder. The resulting adhesive composition, particularly a pressure-sensitive adhesive composition, can be formed into the desired layer form, for example, by calendering onto a substrate or release liner. During the processing of the polymer system into adhesive formulations, particularly pressure-sensitive adhesive compositions, the polymer system can be mixed with other components. These other components can be selected from: other polymers; tackifying resins; fillers, such as conductive fillers, thermally conductive fillers, etc.; flame retardants, such as ammonium polyphosphate and its derivatives; foaming agents; anti-aging agents; light stabilizers; plasticizers; and compounding particles.

[0104] The pressure-sensitive adhesive composition of the present invention can be used as is, for example, in the form of a laminate or a carrier-free layer of the pressure-sensitive adhesive composition of the present invention, also referred to as a "transfer tape". This transfer tape is preferably applied only to materials that temporarily protect the bonding surface, facilitate handling, and facilitate the application of the pressure-sensitive adhesive composition. Such materials are also referred to as release liner or simply "liner" and are generally easy to remove, particularly by a suitable surface coating. A liner may also be provided on a second side of the transfer tape.

[0105] Release liner materials, particularly carrier materials, are anti-stick (coated or treated) on one side or preferably on both sides. Various types of paper, optionally combined with a stabilized extrusion coating, are suitable as carrier materials for release liner materials. Other suitable liner carrier materials include films, particularly polyolefin films, such as those based on ethylene, propylene, butene, and / or hexene. Preferred carrier materials are paper, such as cellophane. Paper is preferred, especially because the concept of components derived from renewable raw materials can therefore also be extended to auxiliary materials for adhesive tapes.

[0106] Silicone systems are frequently used as anti-stick and peel-off coatings. Commonly used pads include, for example, silicone-coated paper and silicone-coated films.

[0107] When using transfer tape to bond to a substrate surface, the backing or pads are then removed, leaving each of the two adhesive sides in direct contact with the substrate surfaces to be bonded together. Therefore, the backing does not constitute a functional component and is correspondingly not considered part of the tape, but rather serves only as an aid in its processing.

[0108] The pressure-sensitive adhesive composition of the present invention can also be used in the construction or production of multilayer tapes. Such multilayer tapes typically include at least one carrier layer and may have outer layers of the pressure-sensitive adhesive composition of the present invention on one or both sides. In the case of double-sided tapes, one or both outer layers may be the pressure-sensitive adhesive composition of the present invention. In the latter case, the pressure-sensitive adhesive composition layers may differ in their chemical composition and / or chemical and / or physical properties and / or their geometry (e.g., layer thickness); however, it is particularly preferred that they are identical in their chemical composition and / or chemical and / or physical properties. Even in the case of multilayer tapes, one or two outer pressure-sensitive adhesive composition layers may be covered by a pad.

[0109] The tape may include additional layers, such as additional carrier layers, functional layers, etc.

[0110] Bio-based materials are preferably selected as carrier materials for multilayer adhesive tapes, and include, for example, materials selected from the following list: paper; bio-based fabrics or nonwovens, such as those made of cotton or viscose; cellophane; cellulose acetate; bio-based polyethylene (PE) and polypropylene (PP) films; films made of thermoplastic starch; and bio-based polyester films, such as those made of polylactide (PLA; polylactic acid), polyethylene terephthalate (PET), polyethylene tetrahydrofuranose (PEF), or polyhydroxyalkanoates (PHA). PET films are particularly preferred as carrier materials. PET films are preferred, for example, because they can be used as recycled materials and thus contribute to sustainability.

[0111] To anchor the pressure-sensitive adhesive composition to a carrier or another substrate, it may be advantageous to treat the adhesive and / or substrate with corona or plasma prior to coating. Furthermore, to anchor the pressure-sensitive adhesive composition layer to another layer, particularly the carrier layer, chemical anchoring (e.g., via a primer) may be advantageous. Detailed Implementation

[0112] Example

[0113] Measurement and testing methods: Method 1 – Determination of the Glass Transition Temperature of Polymers The static glass transition temperature of the polymer was determined using dynamic scanning calorimetry (DSC). For this purpose, 5 mg of the untreated sample of the polymer was weighed into an aluminum crucible (25 µl volume) and sealed with a perforated cap. Measurements were performed using a DSC204 F1 from Netzsch. The experiments were conducted under nitrogen inertization. The sample was first cooled to -150°C, then heated to +150°C at a rate of 10 K / min, and then cooled again to -150°C. A second heating curve was then run at 10 K / min, and the change in heat capacity was recorded. The glass transition temperature is shown in the thermogram (heat flow-temperature plot, see [link]). Figure 1 It was identified as a ladder in the text.

[0114] The glass transition temperature Tg was obtained as follows (see Figure 1 ): The corresponding linear segments of the measurement curves before and after the step extend in the direction of increasing temperature (segment before the step) or decreasing temperature (segment after the step) (extensions and sums). In the step region, a fitted line is drawn parallel to the y-axis such that it intersects the two extensions, thus forming two regions of equal area (between the corresponding extensions, the fitted line, and the measurement curve). The intersection of the fitted line and the measurement curve, thus positioned, gives the glass transition temperature.

[0115] Method 2 – Determination of Molar Mass

[0116] The weight-average molar mass M given in this article w The value refers to the established determination by gel permeation chromatography (GPC). This determination was performed on 100 µl of clearly filtered sample (sample concentration 3 g / L). Tetrahydrofuran was used as the eluent. Measurements were performed at 25°C.

[0117] Using PSS-SDV columns, 5 µm, 10 3 Å, 8.0 mm × 50 mm (Specifications below are in the following order: type, particle size, inner diameter × length; 1 Å = 10 -10 m) as the pre-column. For separation, a combination of PSS and SDV columns was used, 5 µm, 10 3 Å, 10 5 Å and 10 6 Å, each 8.0 mm × 300 mm (columns from Agilent; via PSS SECcurity) 2(Differential refractometer detection). Flow rate was 1.0 ml per minute. Calibration was performed using a ReadyCal-Kit Poly(styrene) high, commercially available from Agilent. The data were universally converted to polymethyl methacrylate (PMMA) using Mark-Houwink parameters K and alpha, so that data are reported in PMMA mass equivalents.

[0118] Weight-average molecular weight M w Determined by gel permeation chromatography (GPC). THF was used as the eluent. Measurements were performed at 23°C. A PSS-SDV pre-column, 5 µm, 10 µm was used. 3 Å, ID 8.0 mm × 50 mm. For separation, a PSS-SDV column was used, 5µm, 10 3 Å, and 10 4 Å and 10 6 Each sample had an ID of 8.0 mm × 300 mm. The sample concentration was 4 g / L, and the flow rate was 1.0 ml per minute. Calibration was performed using a ReadyCal-KitPoly (styrene) high, commercially available from Mainz PSS Polymer Standard Service GmbH.

[0119] As is well known to those skilled in the art, polydispersity (PDI) is defined as the ratio of weight-average molecular weight to number-average molecular weight.

[0120] Method 3 – Dynamic Mechanics Analysis (DMA)

[0121] G' and G'' were determined using a rheometer. The material under study was subjected to sinusoidal oscillating shear stress in a plate-plate configuration. In a shear stress-controlled instrument, deformation as a function of time, and the time lag of this deformation relative to the application of the shear stress, were measured. This time lag is called the phase angle δ.

[0122] The energy storage modulus G' is defined as follows: G' = (τ / γ) cos(δ) (τ = shear stress, γ = strain, δ = phase angle = phase shift between shear stress and strain vectors). The loss modulus G'' is defined as: G'' = (τ / γ) sin(δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between shear stress and deformation vectors).

[0123] tan δ = G'' / G'.

[0124] Instrument: MCR 302e rheometer (Anton Paar), plate-to-plate, ø 12 mm

[0125] Deformation: Dynamic Adjustment

[0126] Measurement frequency: 1 Hz

[0127] Measurement method: frequency scanning

[0128] Measurement range: 10 -5 – 10 2 Hz

[0129] Method 4 – Determination of Static Shear Strength (Shear Life; SSZ)

[0130] Shear strength is a measure of the internal strength of an adhesive, and is tested in the so-called static shear test as follows: Tests were conducted under standard conditions (23°C, 50% relative humidity; SSZ (RT) 1 kg) using a 1 kg weight. A 1.3 cm wide sample strip (50 µm polymer layer on a 36 µm etched PET film) was bonded to a polished steel plate over a 2 cm length by rolling with a 2 kg roller (twice back and forth). The plate was equilibrated under the test conditions for 30 minutes without loading. The test weight (1 kg) was then attached, applying shear stress parallel to the bonded surface, and the time until adhesive failure was measured. Measurements are given in minutes. The median of three individual measurements is reported. A shear lifetime of at least 10,000 minutes at room temperature is considered a good result.

[0131] Shear life was determined under test conditions of 70 ± 1°C and 10% ± 10% relative humidity (“SSZ (70°C) 0.5 kg”), performed in the same manner as described above, wherein the prepared plates were equilibrated under test conditions of 70°C for 30 minutes and then suspended with a weight of 0.5 kg. A shear life of at least 100 minutes at 70°C was considered a good result for temperature stability. A shear life of at least 300 minutes at 70°C was considered a very good result for temperature stability.

[0132] Method 5 – Adhesion to Steel

[0133] Adhesion strength was determined under test conditions of 23°C ± 1°C and 50% ± 5% relative humidity. Samples were cut to a width of 20 mm and bonded to a steel sheet (ASTM). The steel sheet was cleaned and conditioned prior to bonding. For this purpose, the sheet was first wiped with solvent and then allowed to air dry for 5 minutes to allow the solvent to evaporate. The side of the tape away from the test substrate was then covered with a 25 µm thick etched PET film, which prevented the sample from stretching during measurement. The test specimen was then rolled onto the substrate. For this purpose, the tape was rolled back and forth five times using a 4 kg roller at a rolling speed of 10 m / min. One minute after rolling, the sheet was placed in a dedicated support. Adhesion strength was measured using a Zwick tensile testing machine; the sample was peeled at a 180° angle at a speed of 300 mm / min. Measurements are given in N / cm and are the average of three individual measurements. An adhesion strength of at least 3 N / cm is considered a good result.

[0134] Method 6 – Determining Viscosity

[0135] In this test, a 5.6 g steel ball is rolled down a 65 mm high ramp (21° inclination) onto a horizontal strip of the adhesive being tested. The distance the ball travels until it stops is measured (test conditions: 23°C, 50% relative humidity). A distance not exceeding 300 mm is considered a good result.

[0136] The ball was cleaned with cellulose and acetone before measurement and conditioned in the test environment for 30 minutes.

[0137] The adhesive is conditioned for 1 day in the test climate before measurement.

[0138] Method 7 – Determination of Shear Adhesion Failure Temperature (SAFT)

[0139] SAFT was determined as follows: A polished steel surface was used as the defined substrate. The adhesive surface element to be tested was cut to a width of 10 mm and a length of approximately 5 cm, and then immediately pressed three times onto the selected substrate (with an area of ​​10 x 13 mm) using a 2 kg steel roller at a feed speed of 10 m / min. Immediately afterwards, a 0.5 N load was applied at a 180° angle, and a temperature ramp of 9°C / min was applied. The temperature was measured when the sample traveled 1 mm. The measurements (in °C) were calculated as the average of two separate measurements. SAFT values ​​exceeding 90°C were considered good results, and SAFT values ​​exceeding 120°C were considered very good results.

[0140] Preparation of polymer A

[0141] A 3 L container, commonly used for free radical polymerization, was loaded with 900 g of n-butyl acrylate (nBA), 3.933 g of 1,4-phenylene bis(methylene)didodecyl dicarbonotrithioate (BM1812; CAS 960256-58-0), and 900 g of ethyl acetate (EtAc). After passing nitrogen through the mixture with stirring for 45 minutes, the reactor contents were heated to 58°C and 0.229 g of Vazo® 67 was added. The reactor contents were then further heated to 65°C. After a 24-hour reaction time, the reactor contents were cooled to 35°C. The conversion was >95%, and polymer A comprised 50% by weight of the polymer solution.

[0142] Polymer A has a weight-average molecular weight M of 238,000 g / mol. w And the polydispersity index (PDI) of 1.46.

[0143] Preparation of polymer B

[0144] A 3 L container, commonly used for free radical polymerization, was loaded with 810 g of 2-ethylhexyl acrylate, 90 g of acrylic acid, 3.159 g of 1,4-phenylenebis(methylene)bisdodecylbis(trithiocarbonate) (BM1812; CAS 960256-58-0), and 900 g of ethyl acetate (EtAc). After passing nitrogen through the mixture with stirring for 45 minutes, the reactor contents were heated to 58°C and 0.092 g of Vazo® 67 was added. The reactor contents were then further heated to 65°C. After a 24-hour reaction time, the reactor contents were cooled to 35°C. The conversion was >95%, and polymer A comprised 50% by weight of the polymer solution.

[0145] Polymer B has a weight-average molecular weight M of 481,000 g / mol. w And the polydispersity index (PDI) of 2.6.

[0146] Preparation of polymer C

[0147] A 3 L container, commonly used for free radical polymerization, was loaded with 900 g of n-butyl acrylate (nBA), 24.516 g of 1,4-phenylenebis(methylene)bisdodecylbis(trithiocarbonate) (BM1812; CAS 960256-58-0), and 900 g of ethyl acetate (EtAc). After passing nitrogen through the mixture with stirring for 45 minutes, the reactor contents were heated to 58°C and 0.715 g of Vazo® 67 was added. The reactor contents were then further heated to 65°C. After a 24-hour reaction time, the reactor contents were cooled to 35°C. The conversion was >95%, and polymer A comprised 50% by weight of the polymer solution.

[0148] Polymer C has a weight-average molecular weight M of 37,200 g / mol. w And the polydispersity index (PDI) of 1.2.

[0149] Preparation of block copolymer BC1

[0150] A 3 L container, commonly used for free radical polymerization, was loaded with a polymer solution of 1,350 g of polymer A, 225 g of isobornyl acrylate (IBOA), and 225 g of ethyl acetate (EtAc). After passing nitrogen through the mixture with stirring for 45 minutes, the reactor contents were heated to 58°C and 0.172 g of Vazo® 67 was added. The reactor contents were then further heated to 65°C. After 3 hours, the mixture was diluted with 300 g of ethyl acetate, and after 5 hours, it was diluted again with 300 g of ethyl acetate. After a 24-hour reaction time, the reactor contents were cooled to 35°C. The conversion rate was >98%.

[0151] The block copolymer BC1 has a weight-average molecular weight M of 706,000 g / mol. w And the polydispersity index (PDI) of 10.2.

[0152] Preparation of block copolymer BC2

[0153] A 3 L container, commonly used for free radical polymerization, was loaded with a polymer solution of polymer A (1350 g), 225 g of dicyclopentyl acrylate (DCPA), and 225 g of ethyl acetate (EtAc). Nitrogen gas was passed through the mixture with stirring for 45 minutes. The reactor contents were then heated to 58°C and 0.172 g of Vazo® 67 was added. The reactor contents were then further heated to 65°C. After 3 hours, the mixture was diluted with 300 g of ethyl acetate, and after 5 hours, it was diluted again with 300 g of ethyl acetate. After a 24-hour reaction time, the reactor contents were cooled to 35°C. The conversion rate was >98%.

[0154] The block copolymer BC2 has a weight-average molecular weight M of 657,000 g / mol. w And the polydispersity index (PDI) of 8.2.

[0155] Preparation of block copolymer BC3

[0156] A 3 L container, commonly used for free radical polymerization, was loaded with a polymer solution of 1417 g of polymer A, 192 g of norbornyl acrylate, and 192 g of ethyl acetate (EtAc). After passing nitrogen through the mixture with stirring for 45 minutes, the reactor contents were heated to 58°C and 0.181 g of Vazo® 67 was added. The reactor contents were then further heated to 65°C. After 3 hours, the mixture was diluted with 300 g of ethyl acetate, and after 5 hours, it was diluted again with 300 g of ethyl acetate. After a 24-hour reaction time, the reactor contents were cooled to 35°C. The conversion rate was >98%.

[0157] The block copolymer BC3 has a weight-average molecular weight M of 696,000 g / mol. w And the polydispersity index (PDI) of 7.0.

[0158] Preparation of block copolymer BC4

[0159] A 3 L container, commonly used for free radical polymerization, was loaded with a polymer solution of polymer B, 153 g of dicyclopentyl acrylate (DCPA), and 153 g of ethyl acetate (EtAc). After passing nitrogen through the mixture with stirring for 45 minutes, the reactor contents were heated to 58°C and 0.052 g of Vazo® 67 was added. The reactor contents were then further heated to 65°C. After 3 hours, the mixture was diluted with 300 g of ethyl acetate, and after 5 hours, it was diluted again with 300 g of ethyl acetate. After a 24-hour reaction time, the reactor contents were cooled to 35°C. The conversion rate was >98%.

[0160] The block copolymer BC4 has a weight-average molecular weight M of 801,000 g / mol. w And the polydispersity index (PDI) of 13.7.

[0161] Preparation of block copolymer BC5 (Comparative Example 2)

[0162] A 3-liter reactor, commonly used for free radical polymerization, was loaded with a polymer solution of 1340 g of polymer C, 230 g of dicyclopentyl acrylate (DCPA), and 230 g of ethyl acetate (EtAc). After passing nitrogen through the mixture with stirring for 45 minutes, the reactor contents were heated to 58°C and 0.532 g of Vazo® 67 was added. The reactor contents were then further heated to 65°C. After 5 hours, the mixture was diluted with 300 g of ethyl acetate. After a 24-hour reaction time, the reactor contents were cooled to 35°C. Conversion >98%.

[0163] The block copolymer BC5 has a weight-average molecular weight M of 52.700 g / mol. w And a polydispersity index (PDI) of 1.5.

[0164] Sample preparation for measurement and testing methods

[0165] Unless otherwise specified, the prepared block copolymer was applied from solution to a silicone-coated release film (50 µm polyester) using a doctor blade and subsequently dried (coating speed 2.5 m / min, drying channel 15 m, temperature: zone 1: 40°C, zone 2: 70°C, zone 3: 95°C, zone 4: 105°C). The mass application rate after drying was 50 g / m. 2 .

[0166] Table 1: Adhesion strength and shear life of block copolymers

[0167] Commercially available LA2330 (Kuraray Co., LTD.; Comparative Example 1) is a block copolymer based on n-butyl acrylate containing approximately 20% by weight PMMA.

[0168] Comparative Example 2 exhibited cohesive failure in the failure modes measured by adhesion strength. Due to insufficient cohesion, Comparative Example 2 is unsuitable for use as a pressure-sensitive adhesive composition.

[0169] For Examples BC2 and BC4, SAFT values ​​and 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 of 1801 minutes [SSZ (70°C) 0.5 kg]. BC4 has a SAFT value of 140°C and a shear life at 70°C of 350 minutes [SSZ (70°C) 0.5 kg].

Claims

1. A pressure-sensitive adhesive composition based on at least one block copolymer BC, having at least one polymer block P(A) and at least one polymer block P(B), wherein - P(A) independently comprises homopolymer or copolymer blocks comprising a total of at least 80% by weight of monomer A selected from methacrylates, methacrylamides and monomers having at least one polymerizable vinyl group; - P(B) independently comprises homopolymer or copolymer blocks comprising a total of at least 80% by weight monomer B selected from methacrylates, methacrylamides, and monomers having at least one polymerizable vinyl group; and Its features are, - the monomers A contain at least 50 wt.-% in total of one or more acrylate monomers A1 of the general structure CH2=C(H)(COOR 1 ); wherein R 1 is independently at each occurrence selected from linear or branched alkyl groups having 4 to 17 carbon atoms; and - The monomer B comprises a total of at least 60% by weight of the material selected from the common structure CH2=C(R) 2 (COOR 3 One or more (meth)acrylate monomers B1; wherein R 2 Each time it appears, it is independently selected from H and CH3; and R 3 Each time it appears, it is independently selected from optionally substituted, cyclic, or polycyclic alkyl groups having at least 6 carbon atoms.

2. The pressure-sensitive adhesive composition according to claim 1, characterized in that, Each of the monomers B1 has a glass transition temperature of the corresponding homopolymer greater than or equal to 90°C, preferably greater than or equal to 100°C, and particularly greater than or equal to 105°C.

3. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, Each of the monomers A1 has a glass transition temperature of the corresponding homopolymer that is less than or equal to 0°C, more preferably less than or equal to -10°C, and particularly preferably less than or equal to -20°C.

4. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, The block copolymer BC has a weight-average molar mass M w ≥ 200,000 g / mol, preferably M w ≥ 350,000 g / mol, with M being particularly preferred. w ≥500,000 g / mol.

5. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, The block copolymer BC has a polydispersity greater than 2, preferably greater than 4, and particularly preferably greater than 6.

6. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, The polymer block P(B) is present in a proportion between 5 and 49% by weight, preferably between 7.5 and 35% by weight, and particularly between 10 and 30% by weight, relative to the total amount of the polymer blocks P(A) and P(B) of the block copolymer BC.

7. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, The block copolymer BC can be described by one or more of the following general formulas: P(A)-P(B)-P(A) (Ia) P(B)-P(A)-P(B) (Ib) P(B)-P(A)-P(B)-P(A)-P(B) (IIa) P(A)-P(B)-P(A)-P(B)-P(A) (IIb) [P(A)-P(B)] n X (IIIa) [P(B)-P(A)] n X (IIIb) [P(B)-P(A)-P(B)] n X (IVa) [P(A)-P(B)-P(A)] n X (IVb) [P(A)-P(B)] n X[P(B)] m (Go) [P(B)-P(A)] n X[P(A)] m (Vb) Where n = 2 to 12, m = 1 to 12, and X represents a bifunctional or multifunctional branched region.

8. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, The polymer blocks P(A) and P(B) are not homogeneously miscible with each other.

9. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, The monomer A1 is selected from n-butyl acrylate, isobutyl acrylate, isoamyl acrylate, n-hexyl acrylate, n-heptyl acrylate, 2-heptyl acrylate, 2-ethylhexyl acrylate, 2-octyl acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, isononyl acrylate, 2-propylheptyl acrylate, n-decyl acrylate, isodecyl acrylate, lauryl acrylate, tetradecyl acrylate, and heptadecanyl acrylate.

10. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, The monomer B1 is selected from the general structure CH2=C(R) 2 (COOR) 3 ); where R 2 For H; and R 3 Each time it appears, it is independently selected from cyclic or polycyclic alkyl groups having 6 to 14 carbon atoms, preferably 7 to 12 carbon atoms.

11. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, The monomer B1 is not isobornyl acrylate.

12. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, The monomer B1 is selected from norborneol acrylate, tricyclodecyl acrylate and dicyclopentyl acrylate, and preferably the monomer B1 is dicyclopentyl acrylate.

13. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, The monomers A and B contain a total of up to 15% by weight, preferably up to 10% by weight, and particularly preferably up to 5% by weight of methyl methacrylate.

14. The pressure-sensitive adhesive composition according to any one of the preceding claims, characterized in that, The monomers A and / or B are substantially free of methyl methacrylate; more preferably free of methyl methacrylate and methacrylamide; and in particular free of any methacrylic acid compounds.

15. The pressure-sensitive adhesive composition according to any one of the preceding claims, comprising at least one block polymer BC in an amount of at least 50% by weight, preferably at least 60% by weight, and particularly preferably 70% by weight relative to the total weight of the pressure-sensitive adhesive composition.

16. A tape comprising a pressure-sensitive adhesive composition according to any one of claims 1 to 15.

17. A method for producing a pressure-sensitive adhesive composition according to any one of claims 1 to 15, characterized in that, At least one polymerization step is carried out in a closed shell and / or RAFT polymerization.

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