Uncrosslinked polyepoxide and adhesive compound comprising said polyepoxide

Abstract

The invention relates to a polyepoxide for use in reactive adhesive compounds, wherein the polyepoxide can be produced by the polymerisation of a monomer composition comprising, based on the mass of the monomer composition: i) one or more first monomers in a combined mass proportion of 50 % or more, wherein the first monomers are selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of formula (I), where R is a linear or branched alkyl group with 1 to 30 C-atoms, and ii) one or more second monomers in a combined mass proportion of 1 % or more, wherein the second monomers are selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of formula (I), where R is a linear or branched organic substituent with 1 to 30 C-atoms that comprises at least one reactive functional group, and / or iii) one or more third monomers in a combined mass proportion of 1 % or more, wherein the third monomers are selected from the group consisting of multiepoxy-functional monomers of formula (I), where R is a linear or branched organic substituent with 2 to 30 C-atoms that comprises at least one epoxy group, wherein the formula corresponds to (I).

Description

[0001] tesa Societas Europaea Norderstedt

[0002] Description

[0003] Uncrosslinked polyepoxide and adhesive composition comprising this polyepoxide

[0004] The invention relates to a polyepoxide for use in reactive adhesives, a corresponding curable adhesive, and an adhesive tape comprising such a curable adhesive. Also disclosed are a process for producing a corresponding polyepoxide and the use of a corresponding adhesive tape for bonding two or more components.

[0005] Joining separate elements is one of the central processes in manufacturing technology. Along with other methods such as welding and soldering, bonding—that is, joining using an adhesive—is playing a particularly important role today. Adhesive tapes represent an alternative to the use of formless adhesives, which are applied, for example, from a tube.

[0006] In this regard, pressure-sensitive adhesive tapes are particularly familiar in everyday use. These tapes are made of a pressure-sensitive adhesive that provides the adhesive effect and is permanently tacky and adhesive under normal ambient conditions. Such pressure-sensitive adhesive tapes can be applied to a substrate by pressure and remain adhered there, but can later be removed more or less residue-free.

[0007] However, another type of adhesive tape is particularly important for use in industrial manufacturing. These curable adhesive tapes, which are sometimes also referred to as reactive adhesive tapes, use a curable adhesive or reactive adhesive. In their intended application state, these curable adhesives have not yet reached their maximum degree of crosslinking and can be cured by external influences, for example, by initiating polymerization in the curable adhesive, thereby increasing the degree of crosslinking. This changes the mechanical properties of the now cured adhesive, with particular increases in viscosity, surface hardness, and strength.The curability of corresponding curable adhesives is regularly achieved through the use of polymerizable compounds, in particular crosslinkable monomers, oligomers or polymers.

[0008] An important class of polymerizable compounds for reactive adhesive tapes are epoxides, which are sometimes also referred to as epoxy resins, whereby many of the epoxy compounds used on an industrial scale today are obtained by reacting mono- or dialcohols with epichlorohydrin.

[0009] Despite the generally advantageous reactivity of the epoxy compounds known from the state of the art in curing reactions, these compounds are considered disadvantageous for some applications due to their physicochemical properties. In particular, many of the commercially relevant epoxy compounds are liquid, which in many cases functionally limits their usability in adhesives, as the cohesion of the adhesive should not be reduced too much. This is particularly relevant when, for a reactive adhesive tape, a certain degree of pressure-sensitive tack is to be achieved before curing for the purpose of optimal processability by the end user. This allows reactive adhesive tapes to be removed, if necessary, with essentially no residue, prior to curing, for example, if an adhesive tape was incorrectly applied.

[0010] In light of the above, there is interest in the field of adhesive technology in obtaining epoxy compounds that possess the crosslinkability necessary for curing, yet exhibit sufficient solubility and advantageous rheological properties, particularly increased viscosity, and which can accordingly be used in the production of high-performance reactive adhesives with advantageous cohesion. It is known from the prior art to use epoxy-functionalized novolaks, in which the increased molecular weight is formed by a backbone made of a phenolic resin. These compounds, whose polymer structure differs significantly from that achievable by polymerizing epoxides, are considered disadvantageous for some applications.

[0011] An alternative approach to this is based on the so-called prepolymerization of monomeric epoxy compounds, i.e. a limited polymerization or oligomerization that increases the molecular weight of the resulting compounds, but does not result in such crosslinking of the monomeric epoxy compounds that they chemically crosslink completely or excessively. A corresponding process is disclosed, for example, in EP 3101047 A1. However, the processes known from the prior art are often perceived as disadvantageous because the desired prepolymerization is often not easy to control. This is due in particular to the fact that the epoxy compounds for use in the subsequent reactive adhesive are usually intended to have the ability to crosslink with one another and accordingly contain two or more epoxy groups.This can easily lead to unwanted crosslinking during polymerization, for example, due to local inhomogeneities in the initiator concentration, resulting in the formation of insoluble precipitates. Furthermore, this procedure reduces the concentration of reactive epoxy groups, so that the reactivity, and especially the possibility of controlled adjustment of reactivity, is often perceived as inadequate.

[0012] Further information on the technological background in the field of epoxy-based adhesives can be found, for example, in “Epoxy Adhesive Formulations”; Edward Petrie; 2005, McGraw-Hill Professional; ISBN 978-0-07-145544-2.

[0013] The primary object of the present invention was to eliminate or at least mitigate the above-described disadvantages of the prior art. In particular, the object of the present invention was to provide uncrosslinked epoxy compounds with advantageous rheological properties that can be used in high-performance reactive adhesives with advantageous cohesion.

[0014] It was an object of the present invention that the epoxy compounds to be specified should have excellent processability in the production of reactive adhesives.

[0015] Furthermore, it was an object of the present invention that the epoxy compounds to be specified should have excellent reactivity in crosslinking reactions, wherein it was a particular object of the present invention that the reactivity should be particularly precisely controllable and adaptable to the respective application requirements.

[0016] In addition, it was a supplementary object of the present invention to provide a curable adhesive composition comprising the epoxy compounds to be specified and a reactive adhesive tape based thereon.

[0017] It was a secondary object of the present invention to provide a process for producing the corresponding uncrosslinked epoxy compounds and a use of the corresponding reactive adhesive tapes.

[0018] The inventors of the present invention have now found that the objects described above can surprisingly be achieved by polyepoxides which can be obtained by co-polymerizing a specific class of cycloaliphatic monoepoxy-functional monomers with specific cycloaliphatic monoepoxy-functional monomers comprising reactive functional groups other than epoxy groups and / or with specific cycloaliphatic multiepoxy-functional monomers, as defined in the claims.

[0019] This specific combination surprisingly makes it possible to obtain particularly efficient non-crosslinked epoxy compounds with advantageous and easily adjustable rheological properties, which enable the establishment of advantageous cohesion in curable adhesives. Due to their sufficient solubility in common solvents, the polyepoxides are easy to process, especially when mixed with other components of the curable adhesive, and allow reliable curing of the curable adhesive in the final application.

[0020] The reactivity of the polyepoxides in the subsequent crosslinking can be advantageously controlled by the cycloaliphatic epoxy-functional monomers with the reactive functional groups.In particular, the use of cycloaliphatic monoepoxy-functional monomers, which comprise reactive functional groups other than epoxy groups, allows the particularly controlled introduction of reactive groups into the polyepoxides, which are available for subsequent chemical crosslinking, without these groups leading to undesired crosslinking during polymerization of the epoxy monomers. This also makes high concentrations of reactive groups accessible in the polyepoxide, which, depending on the design, can be precisely controlled via the curing mechanism selected for the curable adhesive, for example during further crosslinking of the adhesive in the adhesive tape and / or during subsequent curing in the final application. Advantageously, however, the reactive groups can also additionally enable chemical bonding to the substrate in the subsequent adhesive application.

[0021] The above-mentioned objects are thus achieved by the subject matter of the invention as defined in the claims. Preferred embodiments of the invention emerge from the subclaims and the following statements.

[0022] Such embodiments, which are designated as preferred below, are combined in particularly preferred embodiments with features of other embodiments designated as preferred. Combinations of two or more of the embodiments designated as particularly preferred below are thus very particularly preferred. Likewise preferred are embodiments in which a feature of an embodiment designated as preferred to any extent is combined with one or more further features of other embodiments designated as preferred to any extent. Features of preferred curable adhesives, adhesive tapes, methods, and uses emerge from the features of preferred polyepoxides.

[0023] To the extent that both specific amounts or proportions of an element, for example, for the monoepoxy-functional or multiepoxy-functional monomers, and preferred embodiments of the element are disclosed below, the specific amounts or proportions of the preferably configured elements are also disclosed. Furthermore, it is disclosed that, in the corresponding specific total amounts or total proportions of the elements, at least some of the elements can be preferably configured, and in particular, that preferably configured elements can in turn be present in the specific amounts or proportions within the specific total amounts or total proportions.

[0024] The invention relates to a polyepoxide for use in reactive adhesives, wherein the polyepoxide can be prepared by polymerizing a monomer composition comprising, based on the mass of the monomer composition: i) one or more first monomers in a combined mass fraction of 50% or more, wherein the first monomers are selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), wherein R represents a linear or branched alkyl group having 1 to 30 C atoms, and ii) one or more second monomers in a combined mass fraction of 1% or more, wherein the second monomers are selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), wherein R represents a linear or branched organic radical having 1 to 30 C atoms, which comprises at least one reactive functional group,and / or iii) one or more third monomers in a combined mass fraction of,

[0025] 1% or more, wherein the third monomers are selected from the group consisting of multiepoxy-functional monomers of the formula (I), wherein R represents a linear or branched organic radical having 2 to 30 C atoms, which comprises at least one epoxy group, wherein the formula (I): corresponds.

[0026] The polyepoxides of the invention are copolymers that are or can be produced by polymerization from a specific monomer composition. In accordance with expert understanding and standard practice in the field of technology, it is expedient to define such copolymers by the production process or the starting materials used for production, since it is largely impossible to conclusively define the corresponding materials in their entirety otherwise.

[0027] In accordance with standard practice in the field of technology, manufacturability is specified with reference to the monomer composition, which, in accordance with expert understanding, includes all monomer components that are converted into monomer units of the polyepoxide during polymerization. Accordingly, other components that may be present in the reaction mixture during polymerization but are not incorporated into the polyepoxide during polymerization, such as solvents, catalysts, or initiators, are not included in the monomer composition.

[0028] The above-defined components of the monomer composition are used as "one or more" in accordance with the understanding of one skilled in the art. The term "one or more" refers, in accordance with industry practice, to the chemical nature of the respective monomers and not to their molar amount. For example, the monomer composition may comprise exclusively methyl 3,4-epoxycyclohexylcarboxylate as the first monomer, which would mean that the monomer composition comprises a plurality of the respective molecules.

[0029] Typically, the mass fractions of the components in the monomer composition are given as combined mass fractions of the one or more monomers, thereby expressing that the mass fraction of the correspondingly formed monomers taken together meets the corresponding criteria, with the mass of the monomer composition forming the reference system in each case.

[0030] The skilled person will tailor the polymerization process used for polymerization to the monomers present in the monomer composition, i.e., in particular, to the available functional groups, and the desired structure of the polyepoxide. In practice, the polymerization will essentially always comprise a cationic polymerization at least in one substep, since this is particularly suitable for the polymerization of epoxy compounds. Processes for cationic polymerization in which the active center of chain propagation is formed by a cation are widely known to the skilled person based on their general specialist knowledge and are among the established processes in the field of epoxy compounds. Preferred embodiments of cationic polymerization are disclosed below.However, particularly in the presence of second monomers which have a reactive functional group other than an epoxy group, the preparation may also comprise further polymerization steps using other polymerization processes. In practice, however, these alternative polymerization processes will generally only make a minor contribution in view of the high epoxide concentrations, so that preference is given to polyepoxides according to the invention which can be prepared essentially exclusively using cationic polymerization. The above statement that the polyepoxide is suitable for use in reactive adhesives, ieFor the skilled person, the term "polyepoxides" suitable as reactive components of reactive adhesives implies that they are uncrosslinked polyepoxides that can be further crosslinked in a reactive adhesive and have physicochemical properties that enable their use in reactive adhesives, particularly with regard to solubility in common solvents. Crosslinked polyepoxides, in which polymerization has led to the formation of a network and which consequently represent essentially insoluble, mostly thermosetting materials in most solvents, do not meet this requirement.

[0031] In accordance with the expert understanding, the term “uncrosslinked” refers to the chemical crosslinking, i.e. the covalent connection of individual copolymer strands to one another to form a network, and not to any physical crosslinking of the copolymer chains, for example by entanglement, phase separation or crystallization.

[0032] The skilled person understands that an uncrosslinked polyepoxide does not necessarily have to be linear, but can also have branched copolymer chains, which can be particularly the case if the monomer composition includes third monomers. Even if the transition from branched copolymer chains to the network of a crosslinked polyepoxide may appear blurred in theory, the uncrosslinked state or the suitability for use in reactive adhesives is relatively easy for the skilled person to determine in practice. The skilled person can determine this, for example, based on the rheological properties or their temperature dependence or with simple solubility tests.

[0033] Based on the typical practical evaluation criteria for determining the sufficiently uncrosslinked state, the inventors believe that properties of the polyepoxides of the invention can be specified for which the suitability for use in reactive adhesives, based on the crosslinking state, or the property "uncrosslinked," is always present. These are specified below and relate to the solubility properties, the gel content, and the weight-average molecular weights. Conversely, in these cases, it is also preferable to implement the polyepoxides of the invention in this form due to their good suitability for use in reactive adhesives.

[0034] In this respect, preference is given to a polyepoxide according to the invention, wherein the polyepoxide is soluble at 23°C in one or more solvents selected from the group consisting of acetone, methyl ethyl ketone, benzine, toluene, ethanol, isopropanol, ethyl acetate, and diethyl ether. A polyepoxide according to the invention is also preferred, wherein the polyepoxide has a mass-related gel content of 10% or less, preferably 5% or less. The mass-related gel content is defined as the ratio of the portion of the polymer that is not soluble in toluene, acetone, or methyl ethyl ketone, preferably not in toluene, at room temperature to the total mass of the polymer. For this purpose, the carefully dried, solvent-free polymer samples are sealed in a nonwoven bag made of polyethylene (Tyvek nonwoven). From the difference between the sample weights before extraction and after a 72-hour extraction by the solvent, ieThe weight fraction of the polymer that is not soluble in the solvent is determined by extraction with toluene, acetone, or methyl ethyl ketone, preferably toluene, at 23 °C. The extraction agent is replaced after 24 hours and 48 hours. The sample mass remaining in the sachet, based on the mass of the polymer, determines the gel fraction, also known as the gel value. This value is expressed as the mean of a triplicate determination in %.

[0035] With regard to the sufficiently uncrosslinked state, a polyepoxide according to the invention is also preferred, wherein the copolymer chains in the polyepoxide have a maximum molecular weight (GPC) of 10 7 g / mol or less, preferably 10 6 g / mol or less. In this respect, additionally or alternatively, a polyepoxide according to the invention is preferred, wherein the polyepoxide has a weight-average molecular weight M w(GPC) of 500,000 g / mol or less, preferably 250,000 g / mol or less, particularly preferably 125,000 g / mol or less, most particularly preferably 50,000 g / mol or less, and / or wherein the polyepoxide has a weight-average molecular weight M w (GPC) in the range from 1000 to 300000 g / mol, preferably in the range from 2000 to 200000 g / mol, particularly preferably in the range from 3000 to 100000 g / mol, with ranges from 1000 to 10000 g / mol or alternatively from 10000 to 100000 g / mol being particularly preferred.

[0036] The weight-average molecular weight M w refer to the determination by gel permeation chromatography (GPC). The determination is carried out using degassed THF as the mobile phase, 100 pL injection volume, and a sample concentration of 1 g / L at a flow rate of 0.5 mL / min at 25 °C on a system consisting of a PSS-SECcurity 1260 HPLC pump, a PSS SDV 10 pm ID 8 mm x 50 mm guard column, a PSS SDV 10 pm 103 Ä ID 8 mm x 300 mm, one PSS SDV 10 pm 10 5 Ä ID 8 mm x 300 mm, one PSS SDV 10 pm 10 7 Ä ID 8 mm x 300 mm and a SECcurity differential refractometer detector (RI). The competent person is aware that during sample preparation, at least 95 wt.% (weight percent) of the sample to be analyzed is dissolved in the respective mobile phase, in this case THF, to obtain a meaningful result.

[0037] The data are recorded and analyzed using the PSS - WinGPC UniChrome version 8.33 software. Calibration is performed using polystyrene standards, which are universally converted to a poly(methyl methacrylate) calibration using the Mark Houwink coefficients K and a.

[0038] Preferred is a polyepoxide according to the invention, wherein the polyepoxide is a thermoplastic solid at 25 °C and 100 kPa pressure.

[0039] According to the above definition, various monomeric epoxy compounds are used in the monomer composition. According to the expert understanding, epoxy compounds are those compounds that carry at least one oxirane group. The monomers used as the first, second, and third monomers are each cycloaliphatic, meaning that their structure includes at least one ring system, but no aromatic ring system. The monomers used as the first, second, and third monomers each have the same basic structure, which is described by formula (I): However, they differ with regard to the respective residue R.

[0040] The first monomers do not have any reactive functional groups in the R radical, i.e., neither epoxy groups nor other reactive functional groups. Rather, in the case of the first monomers, the R radical is an alkyl group, which may be linear or branched in the usual way, with linear radicals being more preferred. In the inventors' opinion, it is in particular the large mass fraction of these monoepoxy-functional monomers, which also do not have any reactive functional groups in the R radical, that enables the advantageous properties of the polyepoxides according to the invention and enables the obtainment of uncrosslinked polyepoxides that are particularly suitable for use in reactive adhesives.

[0041] The inventors have thus succeeded in specifying particularly preferred embodiments for the first monomers with which, in the opinion of the inventors, particularly advantageous polyepoxides according to the invention can be obtained starting from the cycloaliphatic monoepoxy-functional monomers of the formula (I) to be used according to the invention, in which R represents a linear or branched, preferably linear, alkyl group having 1 to 30 C atoms. Preference is given to a polyepoxide according to the invention in which the first monomers are selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), where R represents a linear or branched, preferably linear, alkyl group having 1 to 20 C atoms, preferably having 1 to 10 C atoms, particularly preferably having 1 to 5 C atoms, where R particularly preferably represents a methyl, ethyl, or propyl group.Particularly preferred is a polyepoxide according to the invention wherein the first monomer is 3,4-epoxycyclohexylcarboxylic acid methyl ester, and / or wherein the monomer composition comprises 3,4-epoxycyclohexylcarboxylic acid methyl ester, preferably in a mass fraction of 50% or more, particularly preferably of 70% or more, very particularly preferably of 90% or more, based on the combined mass fraction of the first monomers.

[0042] The second monomers are also monoepoxy-functional monomers, but unlike the first monomers, they have at least one reactive functional group in the R radical. The term "reactive functional group" is clear to the person skilled in the art, who also understands that this reactive functional group in a monoepoxy-functional monomer according to formula (I) cannot itself be an epoxy group, since formula (I) already has an epoxy group.The inventors have also succeeded in specifying particularly preferred embodiments for the second monomers with which, in the opinion of the inventors, particularly advantageous polyepoxides according to the invention can be obtained starting from the cycloaliphatic monoepoxy-functional monomers of the formula (I) in which R represents a linear or branched, preferably linear, organic radical having 1 to 30 C atoms which comprises at least one reactive functional group, and which are particularly well suited for targeted subsequent crosslinking via the corresponding functional groups.

[0043] In this respect, preference is given firstly to a polyepoxide according to the invention, wherein the second monomers are selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), wherein R represents a linear or branched, preferably branched, organic radical having 2 to 20 C atoms, preferably having 3 to 10 C atoms, which comprises at least one reactive functional group.Additionally or alternatively, preference is given to a polyepoxide according to the invention, wherein the reactive functional group is selected from the group consisting of alkoxysilane groups, hydroxyl groups, amine groups, isocyanate groups, carboxylic acid groups, carboxylic acid anhydrides and C=C double bonds, preferably selected from the group consisting of alkoxysilane groups, hydroxyl groups, carboxylic acid groups, carboxylic acid anhydrides and C=C double bonds, particularly preferably selected from the group consisting of hydroxyl groups and C=C double bonds, and / or wherein the second monomers are selected from the group consisting of acrylates, methacrylates and vinyl ethers, preferably from the group consisting of acrylates and methacrylates.Particularly preferred is a polyepoxide according to the invention, wherein the second monomer is ((3,4-epoxycyclohexyl)methyl)methacrylate, and / or wherein the monomer composition comprises ((3,4-epoxycyclohexyl)methyl)methacrylate, preferably in a mass fraction of 50% or more, particularly preferably of 70% or more, very particularly preferably of 90% or more, based on the combined mass fraction of the second monomers.

[0044] With a view to achieving pronounced crosslinkability, the inventors believe it is possible to design the second monomers with several reactive functional groups, which may be the same or different, depending on whether different reactivity in the side chains is desired. Therefore, a polyepoxide according to the invention is preferred in which the second monomers comprise two or more reactive functional groups, in particular similar reactive functional groups.

[0045] In addition or alternatively to the second monomers, the subsequent crosslinkability of the polyepoxides according to the invention can also be made possible by the third monomers, which, in contrast to the second monomers, comprise at least one epoxy group in the radical R and are therefore multiepoxy-functional monomers.

[0046] In the opinion of the inventors, a polyepoxide according to the invention is preferred starting from the multiepoxy-functional monomers of the formula (I) in which R stands for a linear or branched, preferably linear, organic radical having 2 to 30 C atoms, which comprises at least one epoxy group, wherein the third monomers are selected from the group consisting of multiepoxy-functional monomers of the formula (I), wherein R stands for a linear or branched, preferably branched, substituted organic radical having 3 to 25 C atoms, preferably having 4 to 20 C atoms, particularly preferably having 6 to 15 C atoms, which comprises at least one epoxy group.

[0047] Preferred is a polyepoxide according to the invention, wherein the epoxy group is an epoxy group or an oxetane group, preferably an epoxy group, and / or wherein the third monomers are selected from the group consisting of bis-epoxy-functional monomers.

[0048] Even though the radical R of the third monomers can theoretically also comprise further reactive functional groups, as disclosed, for example, above for the second monomers, it is preferred if the third monomers in the radical R do not comprise any further reactive functional groups apart from one or more epoxy groups.

[0049] Particularly preferred is a polyepoxide according to the invention, wherein the third monomer is a bis-epoxycyclohexyl derivative, preferably ((3,4-epoxycyclohexyl)methyl-3,4-epoxycyclohexylcarboxylate, and / or wherein the monomer composition comprises a bis-epoxycyclohexyl derivative, preferably (3,4-epoxycyclohexyl)methyl-3,4-epoxycyclohexylcarboxylate, preferably in a mass fraction of 50% or more, particularly preferably of 70% or more, very particularly preferably of 90% or more, based on the combined mass fraction of the third monomers.

[0050] In the context of the present invention, the term "monomers" is to be understood broadly and serves primarily to clearly distinguish the starting compounds from the copolymer of the polyepoxide. The term expresses that the monomers are to be incorporated into the copolymer. The skilled person understands that the term "monomers" also encompasses low-molecular-weight compounds that could be regarded as oligomers of one or more of the monomers. In accordance with the skilled person's understanding, this is expedient because oligomerization can occur unnoticed and the resulting oligomers, within the meaning of the above definition, can be prepared from the corresponding monomers anyway, so that the presence of oligomers, as an intermediate stage, would have no influence on the producibility of the polyepoxides according to the invention from the monomer composition.In this context, preference is given to a polyepoxide according to the invention, wherein the first monomers and / or the second monomers, preferably the first monomers and the second monomers, have a molecular weight in the range from 75 to 1000 g / mol, preferably in the range from 100 to 500 g / mol, wherein the molecular weight is particularly preferably in the range from 100 to 200 g / mol or in the range from 200 to 350 g / mol or in the range from 350 to 500 g / mol. Additionally or alternatively, preference is given to a polyepoxide according to the invention, wherein the third monomers have a molecular weight in the range from 75 to 1000 g / mol, preferably in the range from 150 to 500 g / mol, wherein the molecular weight is particularly preferably in the range from 150 to 250 g / mol or in the range from 250 to 350 g / mol or in the range from 350 to 500 g / mol.

[0051] As explained above, in the inventors' estimation, the high minimum proportion of first monomers and the specific basic structure of the cycloaliphatic epoxy-functional monomers according to formula (I) in particular open up the possibility of obtaining advantageous, uncrosslinked polyepoxides. Based on this, the physicochemical properties of the polyepoxides according to the invention can advantageously be precisely adapted to the respective requirements and the desired crosslinking behavior by varying the mass ratios in the monomer composition. The proportion of reactive side chains with epoxy groups or other reactive functional groups can be increased as needed.

[0052] Because of the different crosslinking chemistry thus opened up, it is explicitly preferred for essentially all embodiments if the monomer composition comprises at least small amounts of second monomers, wherein in particular the combination of second and third monomers is also particularly favorable in the opinion of the inventors, since in this case, if non-epoxy functionalities are present in the polyepoxide, branching can be achieved via the third monomers, by means of which the rheological properties of the polyepoxides according to the invention can be optimized.

[0053] In this respect, the inventors have succeeded in specifying mass ratios and mass fractions of the various monomers with which, in the inventors' opinion, particularly high-performance polyepoxides according to the invention can be obtained. Firstly, preferred ranges for the mass fractions of the respective monomers were identified. Preference is given to a polyepoxide according to the invention wherein the combined mass fraction of the first monomers is 70% or more, preferably 80% or more, particularly preferably 90% or more, very particularly preferably 95% or more, based on the mass of the monomer composition. Preference is also given to a polyepoxide according to the invention wherein the combined mass fraction of the first monomers is in the range from 50 to 99%, preferably in the range from 55 to 98%, particularly preferably in the range from 60 to 95%, very particularly preferably in the range from 65 to 90%, based on the mass of the monomer composition.For adaptation to the requirements of different applications, a polyepoxide according to the invention is preferred, wherein the combined mass fraction of the first monomers is in the range from 70 to 80% or in the range from 80 to 90% or in the range from 90 to 95%, based on the mass of the monomer composition.

[0054] With regard to the second monomers, preference is given to a polyepoxide according to the invention, wherein the combined mass fraction of the second monomers is 2% or more, preferably 5% or more, particularly preferably 10% or more, based on the mass of the monomer composition. In this respect, preference is also given to a polyepoxide according to the invention, wherein the combined mass fraction of the second monomers is in the range from 1 to 40%, preferably in the range from 2 to 30%, particularly preferably in the range from 5 to 20%, based on the mass of the monomer composition. Again, for adaptation to the requirements of different application purposes, preference is given to a polyepoxide according to the invention, wherein the combined mass fraction of the third monomers is in the range from 1 to 10% or in the range from 10 to 35% or in the range from 35 to 49%, based on the mass of the monomer composition.

[0055] As explained above, a polyepoxide according to the invention is preferred, wherein the monomer composition comprises second monomers and third monomers, preferably in a mass ratio in the range from 10:1 to 1:10, more preferably in a mass ratio in the range from 5:1 to 1:5, most preferably in a mass ratio in the range from 2:1 to 1:2. Additionally or alternatively, a polyepoxide according to the invention is particularly preferred, wherein the combined mass fraction of the second monomers and the third monomers is 2% or more, preferably 4% or more, more preferably 10% or more, based on the mass of the monomer composition, and / or wherein the combined mass fraction of the second monomers and the third monomers is in the range from 2 to 40%, preferably in the range from 4 to 30%, more preferably in the range from 10 to 20%, based on the mass of the monomer composition.For various application scenarios, preference is additionally or alternatively given to a polyepoxide according to the invention, wherein the combined mass fraction of the second monomers and the third monomers is in the range from 1 to 5% or in the range from 5 to 20% or in the range from 20 to 40%, since with these ranges in the crosslinking, networks of different densities can be obtained, with which the application properties can be particularly well tailored to the desired requirements, in particular with regard to pressure-sensitive adhesion and performance as a structural adhesive.

[0056] As explained above, a polyepoxide according to the invention is preferred, wherein the monomer composition comprises second monomers and third monomers, preferably in a mass ratio in the range from 10:1 to 1:10, more preferably in a mass ratio in the range from 5:1 to 1:5, most preferably in a mass ratio in the range from 2:1 to 1:2. Additionally or alternatively, a polyepoxide according to the invention is particularly preferred, wherein the combined mass fraction of the second monomers and the third monomers is 2% or more, preferably 4% or more, more preferably 10% or more, based on the mass of the monomer composition, and / or wherein the combined mass fraction of the second monomers and the third monomers is in the range from 2 to 40%, preferably in the range from 4 to 30%, more preferably in the range from 10 to 20%, based on the mass of the monomer composition.

[0057] The person skilled in the art will understand that those polyepoxides according to the invention in which the presence of second monomers or third monomers is mandatory are also preferred. Based on this, polyepoxides according to the invention are preferred in which first monomers in the monomer composition are predominantly, preferably exclusively, combined with second monomers or third monomers, and / or wherein the monomer composition does not comprise any third monomers or any second monomers.

[0058] Against this background, preference is given to a polyepoxide according to the invention, wherein the monomer composition comprises first monomers and second monomers, preferably in a mass ratio in the range from 1:1 to 99:1, particularly preferably in a mass ratio in the range from 1.5:1 to 49:1, very particularly preferably in a mass ratio in the range from 2.5:1 to 9:1. Additionally or alternatively, preference is given to a polyepoxide according to the invention, wherein the combined mass fraction of the first monomers and the second monomers is 80% or more, preferably 90% or more, particularly preferably 95% or more, very particularly preferably 99% or more, especially preferably 100%, based on the mass of the monomer composition.

[0059] Against this background, preference is alternatively given to a polyepoxide according to the invention, wherein the monomer composition comprises first monomers and third monomers, preferably in a mass ratio in the range from 1:1 to 99:1, particularly preferably in a mass ratio in the range from 1.5:1 to 49:1, very particularly preferably in a mass ratio in the range from 2.5:1 to 9:1. Additionally or alternatively, preference is given to a polyepoxide according to the invention, wherein the combined mass fraction of the first monomers and the third monomers is 80% or more, preferably 90% or more, particularly preferably 95% or more, very particularly preferably 99% or more, particularly preferably 100%, based on the mass of the monomer composition.

[0060] Even if it is in principle possible to provide further monomers in the monomer composition which are not first, second or third monomers, in order to obtain particularly high-performance polyepoxides it is, in the opinion of the inventors, explicitly preferred to form the polyepoxides according to the invention as largely as possible from the corresponding specific epoxy compounds. Therefore, a polyepoxide according to the invention is preferred wherein the combined mass fraction of the first monomers, the second monomers and the third monomers is 80% or more, preferably 90% or more, particularly preferably 95% or more, based on the mass of the monomer composition, and / or wherein the combined mass fraction of the first monomers, the second monomers and the third monomers is in the range from 60 to 99%, preferably in the range from 65 to 98%, particularly preferably in the range from 70 to 95%, based on the mass of the monomer composition.

[0061] As explained above, it is possible for the monomer composition to also comprise further monomers, which can be particularly advantageous for adjusting the physicochemical properties. Preference is given to a polyepoxide according to the invention, wherein the monomer composition comprises one or more further monomers, preferably in a combined mass fraction of 2% or more, particularly preferably 5% or more, very particularly preferably 10% or more, based on the mass of the monomer composition, and / or preferably in a combined mass fraction in the range from 1 to 45%, preferably in the range from 2 to 40%, particularly preferably in the range from 5 to 35%, based on the mass of the monomer composition.

[0062] With regard to the additional monomers, the use of diepoxy-functional monomers that are not third monomers is initially preferred. In this respect, a polyepoxide according to the invention is preferred, wherein the monomer composition comprises at least one diepoxy-functional monomer selected from the group consisting of bis-epoxy monomers based on bisphenol A, bisphenol S, or bisphenol F, in particular bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, and bisphenol F diglycidyl ether.

[0063] In an advantageous embodiment, the polyepoxide contains at least one oxetane monomer as a further monomer, in particular multifunctional oxetane monomers, since the resulting “spacer” between the ether groups in the polyepoxide is longer.Accordingly, a polyepoxide according to the invention is preferred, wherein the monomer composition comprises at least one oxetane monomer, preferably a multiepoxy-functional oxetane monomer, wherein the oxetane monomer is preferably not a third monomer, wherein the oxetane monomer is particularly preferably selected from the group consisting of (3-ethyloxetan-3-yl)methanol and 3,3'-[oxybis(methylene)]bis(3-ethyloxetanes), wherein the combined mass fraction of all oxetane monomers which are not third monomers is preferably in the range from 10 to 40%, particularly preferably in the range from 10 to 20% or in the range from 20 to 30 or in the range from 30 to 40%, based on the mass of the monomer composition.In particularly preferred embodiments, the oxetane monomer comprises, in addition to the one or more epoxy groups, also one or more further reactive functional groups, preferably those as described above for the second monomers.

[0064] In addition, for certain applications, the addition of vinyl ethers to the monomer composition is advantageous, which can also be polymerized via cationic polymerization.A polyepoxide according to the invention is therefore preferred, wherein the monomer composition comprises at least one vinyl ether monomer, wherein the vinyl ether monomer is preferably not a second monomer or third monomer, wherein the combined mass fraction of all vinyl ether monomers which are not second monomers or third monomers is preferably in the range from 10 to 40%, particularly preferably in the range from 10 to 20% or in the range from 20 to 30 or in the range from 30 to 40%, based on the mass of the monomer composition, and / or wherein the vinyl ether monomer has a molar mass in the range from 60 to 1000 g / mol, preferably in the range from 80 to 500 g / mol, wherein the molar mass is particularly preferably in the range from 80 to 200 g / mol or in the range from 200 to 350 g / mol or in the range from 350 to 500 g / mol.

[0065] The inventors have succeeded in identifying particularly favorable production conditions for the production of the polymers, with which advantageous, uncrosslinked polyepoxides can be reliably obtained. Due to the high relevance of cationic polymerization, explicit preference is given to a polyepoxide according to the invention, which can be prepared by polymerizing the monomer composition initiated by a cationic initiator, the cationic initiator preferably being used in a molar fraction in the range of 0.005 to 1%, based on the number of epoxide groups in the monomer composition. Additionally or alternatively, preference is given to a polyepoxide according to the invention, the cationic initiator preferably being added stepwise or continuously.

[0066] In a preferred embodiment, the initiator is first dissolved in at least one solvent, and the resulting initiator solution is metered into the monomer composition and, if present, the solvent. Organic polar aprotic solvents such as acetone, methyl ethyl ketone, diethyl ketone, dimethyl sulfoxide, N,N-dimethylformamide, and acetonitrile are preferred for dissolving the initiator, with acetone and methyl ethyl ketone being particularly preferred.

[0067] Cationic initiators are generally familiar to those skilled in the art from the prior art. The polyepoxides according to the invention can be prepared particularly advantageously if the cationic initiator is selected from the group consisting of cationic photoinitiators and cationic thermal initiators, with latent, thermally activatable cationic initiators (TAG; so-called "thermal acid generators") being particularly preferred. Accordingly, a polyepoxide according to the invention is preferred, wherein the polyepoxide is preparable by polymerizing the monomer composition initiated by a cationic thermal initiator or cationic photoinitiator, particularly preferably by a latent, thermally activatable cationic initiator.

[0068] Suitable TAGs are known to those skilled in the art and are commercially available from numerous suppliers. Preference is given to TAGs comprising a cation selected from the group consisting of 4-substituted benzylanilinium, 4-substituted benzylpyridinium, 4-substituted benzylphosphonium, S-substituted diphenylsulfonium, and substituted arylbenzylsulfonium, preferably 4-substituted benzylanilinium.

[0069] In principle, the TAG can contain any anion, with weakly coordinating anions such as tetrafluoroborate (BF4), hexafluorophosphate (PFe), hexafluoroantimonate (SbF6), tetrakis(pentafluorophenyl)borate (B(C6F5)4-), and trifluoromethylsulfonate (F3CSO3) being preferred. Trifluoromethylsulfonate (F3CSO3) and hexafluoroantimonate (SbF6) are particularly preferred.

[0070] Advantageous combinations of a TAG consisting of cation and anion are those in which the resulting initiator has an activation temperature in the range from 50 °C to 150 °C, with the person skilled in the art preferably adjusting the activation energy to the respective application requirements, with a range from 80 °C to 120 °C being particularly preferred in many cases in order to be able to carry out the polymerization at a comparatively moderate activation temperature and nevertheless enable clearly defined initiation. The activation temperature of reactive or chemically activatable adhesives in general or of the TAG used is determined calorimetrically using differential scanning calorimetry (DSC) in accordance with DIN EN ISO 11357-3:2013-04. For this purpose, approximately 20 mg of the sample is weighed into an aluminum crucible and introduced into the measuring device (device: DSC 204 F1, Netzsch). Two heating curves are then recorded at a heating rate of 10 K / min.The samples are measured in aluminum crucibles with perforated lids and a nitrogen atmosphere. A chemical reaction such as the activation of the TAG is evident as an exothermic peak in the thermogram. The onset temperature is recorded as the activation temperature. This is determined for a peak as the intersection point of the virtual interpolated baseline and the tangent drawn at the inflection point of the peak beginning (according to DIN EN ISO 11357-1:2010-03). The reaction enthalpy in J / g is obtained by integrating the curing peak.

[0071] Sulfonium, iodonium, and metallocene-based systems, which are commercially available from a variety of suppliers, can be used as initiators for cationic UV-induced curing of epoxy compounds. Examples of sulfonium-based cations can be found in US Pat. No. 6,908,722 B1. Examples of anions that serve as counterions for the above-mentioned cations include tetrafluoroborate, tetraphenylborate, hexafluorophosphate, perchlorate, tetrachloroferrate, hexafluoroarsenate, hexafluoroantimonate, pentafluorohydroxyantimonate, hexachloroantimonate, tetrakispentafluorophenylborate, tetrakis(pentafluoromethylphenyl)borate, bi(trifluoromethylsulfonyl)amide, and tris(trifluoromethylsulfonyl)methide. In addition, especially for iodonium-based initiators, chloride, bromide or iodide are also conceivable as anions, although initiators that are essentially free of chlorine and bromine are preferred.A powerful example of such a system is triphenylsulfonium hexafluoroantimonate. Other suitable initiators are disclosed, for example, in US 3,729,313 A, US 3,741,769 A, US 4,250,053 A, US 4,394,403 A, US 4,231,951 A, US 4,256,828 A, US 4,058,401 A, US 4,138,255 A, and US 2010 / 063221 A1.

[0072] Konkrete Beispiele für einsetzbare Sulfonium-Salze sind Triphenylsulfoniumhexafluoroarsenat, Triphenylsulfoniumhexafluoroborat, Triphenylsulfoniumtetrafluoroborat, Triphenylsulfoniumtetrakis-(pentafluoro- benzyl)-borat, Methyldiphenylsulfoniumtetrafluoroborat, Methyldiphenyl- sulfoniumtetrakis-(pentafluorobenzyl)-borat, Dimethylphenylsulfoniumhexafluoro- phosphat, Triphenylsulfoniumhexafluorophosphat, Triphenylsulfoniumhexa- fluoroantimonat, Diphenylnaphthylsulfoniumhexafluoroarsenat, T ritolyl- sulfoniumhexafluorophosphat, Anisyldiphenylsulfoniumhexafluoroantimonat, 4- Butoxyphenyldiphenylsulfoniumtetrafluoroborat, 4-Chlorophenyldiphenyl- sulfoniumhexafluoroantimonat, Tris-(4-phenoxyphenyl)-sulfoniumhexafluoro- phosphat, Di-(4-ethoxyphenyl)-methylsulfoniumhexafluoroarsenat, 4- Acetylphenyldiphenylsulfoniumtetrafluoroborat, 4-Acetylphenyldiphenylsulfonium- tetrakis-(pentafluorobenzyl)-borat, Tris-(4-thiomethoxyphenyl)-sulfoniumhexa- fluorophosphat,Di-(methoxysulfonylphenyl)-methylsulfoniumhexafluoro- antimonat, Di-(methoxynaphthyl)-methylsulfoniumtetrafluoroborat, Di-(methoxy- naphthyl)-methylsulfoniumetrakis-(penta-fluorobenzyl)-borat, Di-(carbomethoxy- phenyl)-methylsulfoniumhexafluorophosphat, (4-Octyloxyphenyl)-diphenyl- sulfoniumtetrakis-(3,5-bis-trifluoromethylphenyl)-borat, Tris-[4-(4-acetylphenyl)- thiophenyl]-sulfoniumtetrakis-(pentafluorophenyl)-borat, Tris-(dodecyl-phenyl)- sulfoniumtetrakis-(3,5-bis-trifluoromethylphenyl)-borat, 4-Acetamidphenyldiphe- nylsulfoniumtetrafluoroborat, 4-Acetamidphenyldiphenylsulfoniumtetrakis-(penta- fluoro-benzyl)-borat, Dimethylnaphthylsulfoniumhexafluorophosphat, T rifluoro- methyldiphenyl-sulfoniumtetrafluoroborat, Trifluoromethyldiphenylsulfonium- tetrakis-(pentafluorobenzyl)-borat, Phenylmethylbenzylsulfoniumhexafluoro- phosphat, 5-Methylthianthreniumhexa-fluorophosphat, 10-Phenyl-9,9-dimethyl- thioxantheniumhexafluorophosphat, 10-Phenyl-9-oxothioxantheniumtetrafluoro- borat,10-Phenyl-9-oxothioxantheniumtetrakis-(pentafluoro-benzyl)-borat, 5- Methyl-10-oxothianthreniumtetrafluoroborat, 5-Methyl-10-oxothianthreni- umtetrakis-(pentafluorobenzyl)-borat und 5-Methyl-10,10-dioxothianthrenium- hexafluorophosphate.,

[0073] Specific examples of usable iodonium salts are diphenyliodonium tetrafluoroborate, di-(4-methylphenyl)iodonium tetrafluoroborate, phenyl-4-methylphenyliodonium tetrafluoroborate, di-(4-chlorophenyl)iodonium hexafluorophosphate, dinaphthyliodonium tetrafluoroborate, di-(4-trifluoromethylphenyl)iodonium tetrafluoroborate, diphenyliodonium hexafluorophosphate, di-(4-methylphenyl)iodonium hexafluorophosphate, diphenyliodonium hexafluoroarsenate, di-(4-phenoxyphenyl)iodonium tetrafluoroborate, phenyl-2-thienyliodonium hexafluorophosphate, 3,5-dimethylpyrazolyl-4-phenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, 2,2'-diphenyliodonium- tetrafluoroborate, di-(2,4-dichlorophenyl)-iodonium hexafluorophosphate, di-(4-bromophenyl)-iodonium hexafluorophosphate, di-(4-methoxyphenyl)-iodonium hexa-fluorophosphate, di-(3-carboxyphenyl)-iodonium hexafluorophosphate, di-(3-methoxycarbonylphenyl)-iodonium hexafluorophosphate, Di-(3-methoxysulfonyl-phenyl)-iodonium hexafluorophosphate,Di-(4-acetamidophenyl)-iodoniumhexa- fluorophosphat, Di-(2-benzothienyl)-iodoniumhexafluorophosphat, Diaryl- iodoniumtristrifluormethylsulfonylmethid wie Diphenyliodoniumhexafluoro- antimonat, Diaryliodoniumtetrakis-(pentafluorophenyl)-borat wie Diphenyl- iodoniumtetrakis-(pentafluorophenyl)-borat, [4-(2-Hydroxy-n-tetradesiloxy)- phenyl]-phenyliodoniumhexafluoroantimonat, [4-(2-Hydroxy-n-tetradesiloxy)- phenyl]-phenyliodoniumtrifluorosulfonat, [4-(2-Hydroxy-n-tetradesiloxy)-phenyl]- phenyliodoniumhexafluorophosphat, [4-(2-Hydroxy-n-tetradesiloxy)-phenyl]- phenyliodoniumtetrakis-(pentafluorophenyl)-borat, Bis-(4-tert-butylphenyl)- iodoniumhexafluoroantimonat, Bis-(4-tert-butylphenyl)-iodoniumhexafluoro- phosphat, Bis-(4-tert-butylphenyl)-iodoniumtrifluorosulfonat, Bis-(4-tert- butylphenyl)-iodoniumtetrafluoroborat, Bis-(dodecylphenyl)-iodoniumhexafluoro- antimonat, Bis-(dodecylphenyl)-iodoniumtetrafluoroborat, Bis-(dodecylphenyl)- iodoniumhexafluorophosphat,Bis-(dodecylphenyl)-iodoniumtrifluoro- methylsulfonat, Di-(dodecylphenyl)-iodoniumhexafluoroantimonat, Di-(dodecyl- phenyl)-iodoniumtriflat, Diphenyliodoniumbisulfat, 4,4'-Dichlorodiphenyl- iodoniumbisulfat, 4,4'-Dibromodiphenyliodoniumbisulfat, 3,3'-Dinitrodiphenyl- iodoniumbisulfat, 4,4'-Dimethyldiphenyliodoniumbisulfat, 4,4'-Bis-succinimido- diphenyliodoniumbisulfat, 3-Nitrodiphenyliodoniumbisulfat, 4,4'-Dimethoxy- diphenyliodoniumbisulfat, Bis-(dodecylphenyl)-iodoniumtetrakis-(pentafluoro- phenyl)-borat, (4-Octyloxyphenyl)-phenyliodoniumtetrakis-(3,5-bis-trifluoromethyl- phenyl)-borat und (Tolylcumyl)-iodoniumtetrakis-(pentafluorophenyl)-borat, und Ferrocenium-Salze (siehe zum Beispiel EP 0 542 716 B1 ) wie r]5-(2,4- cyclopentadien-1 -yl)-[(1 ,2,3,4,5,6,9)-(1 -methylethyl)-benzol]-eisen.,

[0074] Photoinitiators are typically used individually or in combinations of two or more photoinitiators. When using photoinitiators, combinations with so-called sensitizers are very helpful for adapting the activation wavelength of the photoinitiation system to the selected emission spectrum. For this, reference is made to literature familiar to those skilled in the art, such as "Industrial Photoinitiators: A Technical Guide" (2010) by AW Green.

[0075] When using a photoinitiator, activation by irradiation can occur initially, repeatedly or continuously.

[0076] In a preferred embodiment, the initiator is not an electron-deficient monoisocyanate and, accordingly, is preferably not selected from the group consisting of p-tolyl isocyanate, o-tolyl isocyanate, and sulfonyl isocyanates, p-toluenesulfonylmethyl isocyanate, o-toluenesulfonylmethyl isocyanate, 4-chlorobenzylsulfonyl isocyanate, o-toluenesulfonyl isocyanate, p-toluenesulfonyl isocyanate, and benzylsulfonyl isocyanate. Preference is given to a polyepoxide according to the invention, wherein the polyepoxide is preparable by polymerization of the monomer composition, which is carried out in a solvent. It is particularly preferred if the solvent is removed after the polyepoxide has been prepared, since this allows particularly pure polyepoxides to be obtained.In addition, for other applications it is preferred if the solvent remains in the polyepoxide after production of the polyepoxide, since the polyepoxides obtained in this way are particularly easy to handle and can be further processed in a simple manner, for example in adhesives or coating materials.

[0077] The solvent is preferably selected from the group consisting of water, organic polar protic solvents, organic polar aprotic solvents and organic non-polar aprotic solvents and mixtures of these solvents, for example mixtures of different organic polar aprotic solvents with one another or mixtures of an organic non-polar aprotic solvent with one or more organic polar protic solvents, with organic aprotic solvents being particularly preferred due to their chemical inertness.These include, for example, pentane, hexane, heptane, (iso)octane, methylcyclohexane, gasoline and other alkanes, benzene, toluene, xylene and other aromatic hydrocarbons, dichloromethane, chloroform, dichloroethane and other halogenated hydrocarbons, dimethyl ether, diethyl ether, methyl tert-butyl ether, diphenyl ether, dibutyl ether, ethyl acetate, methyl ethyl ketone, acetone, n-butyl acetate and other carboxylic acid esters, as well as carbon disulfide. Toluene, methylcyclohexane, n-butyl acetate, ethyl acetate, and methyl ethyl ketone are particularly preferred, as they are excellent at dissolving the reactants used.

[0078] The solvent can, in principle, be used in any mixing ratio with the monomer composition, the initiator, and optionally the other reactants, although an addition in a mass fraction of 5% or more (based on the mass of the resulting total formulation) is preferred. The range from 5% to 40% is particularly preferred, as the solvent usage can be kept low. Furthermore, the range from 70% to 95% is particularly preferred, as this results in solutions with a low polyepoxide content and thus minimizes the risk of gelling. The range from 40% to 70% is very particularly preferred, as this represents a good compromise between the amount of solvent and the risk of gelling.

[0079] An important process variable for controlling the molecular weight of the polyepoxides is temperature. For essentially all embodiments, particular preference is given to a polyepoxide according to the invention, wherein the polyepoxide is preparable by polymerizing the monomer composition at a temperature in the range from 50 to 150°C, preferably in the range from 60 to 130°C, with the polymerization of the monomer composition particularly preferably being carried out at a temperature in the range from 50 to 90°C or in the range between 90 and 120°C. The range from 50 to 90°C is preferred because the reaction progresses relatively slowly under these conditions and the reaction is easily controllable, whereas the range between 90 and 120°C is preferred because this achieves a balanced ratio of control and reaction rate.

[0080] The skilled person understands that a preferred polymer structure can be derived from the above statements, in which the polymer comprises the monomer units derived from the respective monomers, wherein the above statements regarding the underlying monomers apply accordingly. The invention is thus closely related to a polyepoxide for use in reactive adhesives, wherein the polyepoxide is a copolymer with a plurality of monomer units of the formula (II): wherein the polyepoxide comprises, based on the mass of the polyepoxide: ib) one or more first monomer units in which R represents a linear or branched alkyl group having 1 to 30 C atoms, in a combined mass fraction of 50% or more, and ii.b) one or more second monomer units in which R represents a linear or branched organic radical having 1 to 30 C atoms which comprises at least one reactive functional group, wherein R does not comprise an epoxy group, in a combined mass fraction of 1% or more, and / or iii.b) one or more third monomer units in which R represents a linear or branched organic radical having 2 to 30 C atoms which comprises at least one epoxy group, in a combined mass fraction of 1% or more.

[0081] In this respect, a process for producing a polyepoxide, preferably a polyepoxide according to the invention, comprising the

[0082] Process steps: a) Producing or providing a monomer composition comprising, based on the mass of the monomer composition: i) one or more first monomers in a combined mass fraction of 50% or more, wherein the first monomers are selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), wherein R represents a linear or branched alkyl group having 1 to 30 C atoms, and ii) one or more second monomers in a combined mass fraction of 1% or more, wherein the second monomers are selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), wherein R represents a linear or branched substituted organic radical having 1 to 30 C atoms, which comprises at least one reactive functional group, and / or iii) one or more third monomers in a combined

[0083] Mass fraction of 1% or more, wherein the third monomers are selected from the group consisting of multiepoxy-functional monomers of the formula (I), wherein R represents a linear or branched substituted organic radical having 2 to 30 C atoms, which comprises at least one epoxy group, wherein the formula (I): and b) polymerizing the monomer composition to obtain the polyepoxide, preferably by means of cationic polymerization.

[0084] In a preferred embodiment of the corresponding process, the polymerization is terminated by an additional step after a predetermined reaction time or upon reaching a desired epoxy monomer conversion. This can be done, for example, by cooling, dilution or the addition of a stopper. For optimal adjustment of the desired, low degree of branching and the targeted molecular weights, preference is therefore given to a corresponding process in which the polymerization in process step b) is slowed down or terminated after the start of the polymerization by one or more slowing measures, wherein the slowing measure is selected from the group consisting of cooling, dilution and addition of a stopper reagent, wherein the slowing measure preferably comprises the addition of a stopper reagent, with the addition of a stopper reagent before cooling being particularly preferred.

[0085] A stopper reagent or stopper is a substance or mixture of substances that interacts with the reactive species of a polymerization through a chemical reaction, thus preventing further chain growth. This chemical interaction is usually based on the establishment of a chemical equilibrium, so that a certain amount of time can elapse between the addition of the stopper and the cessation of polymerization. In the context of the present invention, a stopper is a substance or mixture that ensures that no further epoxy monomer conversion can be observed at the latest 30 minutes after addition.The stopper reagent particularly preferably contains an organic or inorganic base such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, potassium acetate, ammonium acetate, sodium acetate, pyridine, pyrrolidine, pyrrole, piperidine, indole, imidazole, pyrazole, imidazolines, (iso)quinoline, purine, pyrimidine, 4-vinylpyridine, or 4-ethylpyridine, with pyridine and 4-ethylpyridine being extremely preferred, as well as preferably a solvent. The addition of a gas as a stopper reagent is also preferred, as this can be distributed particularly quickly in the reaction mixture. The use of ammonia is particularly preferred in this case.

[0086] In light of the above, a corresponding process is preferred, wherein the polymerization in process step b) is carried out such that an epoxy group conversion of 10% or more, preferably of 30% or more, is achieved, wherein the epoxy group conversion is preferably in the range from 20 to 35%. If no third monomers are used whose second epoxy group is to be obtained, a corresponding process is even preferred, wherein the polymerization in process step b) is carried out such that an epoxy group conversion of 50% or more, very particularly preferably of 70% or more, especially preferably of 90% or more, is achieved, wherein the epoxy group conversion is preferably in the range from 35 to 60% or in the range from 60 to 100%.

[0087] Furthermore, preferred embodiments for the corresponding process result from the above statements on the producibility of the polyepoxides according to the invention.

[0088] A corresponding process is preferred, wherein the polymerization of the monomer composition is initiated by a cationic initiator, wherein the initiator is preferably used in a molar fraction in the range from 0.005 to 1%, based on the number of epoxide groups in the monomer composition, and / or wherein the initiator is preferably added stepwise or continuously.

[0089] Thus, a corresponding process is also preferred, wherein the polymerization of the monomer composition is initiated by a cationic thermal initiator or cationic photoinitiator, particularly preferably by a latently thermally activatable cationic initiator.

[0090] A corresponding process is also preferred, wherein the polymerization of the monomer composition is carried out in a solvent.

[0091] Thus, furthermore, a corresponding process is preferred, wherein the polymerization of the monomer composition is carried out at a temperature in the range from 50 to 150 °C, preferably in the range from 60 to 130 °C, wherein the polymerization of the monomer composition is particularly preferably carried out at a temperature in the range from 50 to 90 °C or in the range between 90 and 120 °C.

[0092] A corresponding process is also preferred, wherein the process is carried out as a semi-batch or fed-batch process. Particularly in the case of the implementation of a preferred monomer composition comprising second monomers, a major advantage of the corresponding process is that the polyepoxides produced can be further crosslinked in a controlled manner, if necessary via the reactive functional groups, whose concentration in the copolymers can be very precisely controlled, before use in an adhesive composition in order to improve their rheological properties.Thus, a corresponding process is preferred, additionally comprising the process step: c) Partial crosslinking of the polyepoxides to increase the weight-average molecular weight Mw, wherein the crosslinking takes place at least partially, preferably predominantly, particularly preferably substantially completely, via the monomer units derived from second monomers and / or third monomers, preferably via the monomer units derived from second monomers.

[0093] The invention also relates to a curable adhesive comprising the polyepoxide according to the invention.

[0094] The curable adhesive composition according to the invention is curable. Due to its ability to cure, the curable adhesive composition can function as a structural adhesive after curing. According to DIN EN 923: 2006-01, structural adhesives are adhesives that form adhesive bonds that can maintain a specified strength in a structure for a specified, extended period of time (according to the ASTM definition: "bonding agents used for transferring required loads between adherends exposed to service environments typical for the structure involved"). These are therefore adhesives for bonds subject to high chemical and physical stresses, which, when cured, contribute to the strengthening of the adhesive tapes. In other words, this is a reactive adhesive composition.

[0095] With a view to the subsequent end use, it is particularly preferred if the curable adhesive is a pressure-sensitive adhesive, the establishment of the cohesion of the adhesive required for pressure-sensitive adhesion being advantageously promoted by the use of the polyepoxides according to the invention. In accordance with the expert understanding, a pressure-sensitive adhesive is an adhesive which has pressure-sensitive adhesive properties, i.e. the property of forming a permanent bond to a substrate even under relatively light pressure. Corresponding pressure-sensitive adhesive tapes can usually be removed from the substrate essentially without residue after use and are generally permanently tacky even at room temperature, which means that they have a certain viscosity and tackiness, so that they wet the surface of a substrate even under light pressure.Without wishing to be bound by this theory, it is often assumed that a pressure-sensitive adhesive can be viewed as an extremely viscous liquid with an elastic component, which consequently exhibits characteristic viscoelastic properties that lead to the permanent inherent tack and pressure-sensitive adhesive capacity described above. It is assumed that with corresponding pressure-sensitive adhesives, mechanical deformation leads to both viscous flow processes and the build-up of elastic restoring forces. The partial viscous flow serves to achieve adhesion, while the partial elastic restoring forces are necessary in particular to achieve cohesion. The relationships between rheology and pressure-sensitive tack are known in the art and are described, for example, in "Satas, Handbook of Pressure Sensitive Adhesives Technology", Third Edition, (1999), pages 153 to 203.To characterise the degree of elastic and viscous components, the storage modulus (G') and the loss modulus (G") are usually used, which can be determined by means of dynamic mechanical analysis (DMA), for example using a rheometer, as disclosed, for example, in WO 2015 / 189323. In the context of the present invention, an adhesive is preferably understood to be pressure-sensitive and thus a pressure-sensitive adhesive if, at a temperature of 23°C in the deformation frequency range from 10° to 10. 1 rad / sec G' and G“ each at least partly in the range of 10 3 up to 10 7 Pa lie.

[0096] The initiators used for the curable adhesive compositions can again be the customary initiators known to the person skilled in the art, with particular preference being given to the use of initiators disclosed above as preferred with regard to the preparation of the polyepoxides.

[0097] It can be seen as an advantage of curable adhesives according to the invention that, beyond the presence of the polyepoxides according to the invention, they are very flexible with regard to the use of typical additives, so that the physicochemical properties can be further adapted specifically to the requirements of the respective application. Thus, a curable adhesive according to the invention is preferred, wherein the curable adhesive comprises one or more further additives, preferably in a combined mass fraction in the range from 0.1 to 50%, preferably in the range from 0.2 to 40%, based on the mass of the adhesive, and / or wherein the one or more further additives are preferably selected from the group consisting of tackifier resins, ageing inhibitors, light stabilizers, UV absorbers, fillers, and rheological additives.

[0098] The invention also relates to an adhesive tape comprising the curable adhesive composition of the invention. Those skilled in the art will understand that the adhesive tape of the invention is a reactive adhesive tape and, in light of the above explanations, preferably a pressure-sensitive adhesive tape.

[0099] An adhesive tape according to the invention is preferred, wherein the adhesive tape comprises a carrier layer or a release layer on which the adhesive is arranged. An adhesive tape according to the invention is also preferred, wherein the adhesive tape comprises a cover layer arranged on the adhesive.

[0100] Finally, the use of an adhesive tape according to the invention for bonding two or more components is disclosed. A preferred use is one in which curing occurs at least partially by reacting a reactive functional group of the polyepoxides according to the invention that is not an epoxy group.

[0101] Preferred embodiments of the invention are further explained and described below with reference to experiments. A. Sample Preparation:

[0102] Polyepoxides E1 to E6 were prepared. A screw-capped vial equipped with a magnetic stir bar and a rubber septum was charged with the respective initiator (0.017–0.400 mol%, see Table 1) and dissolved in acetone to form a 5% solution.

[0103] The monomer composition (approx. 5.0 g) and the solvent (approx. 5.0 g) were added, the vial was sealed, and the reaction mixture was stirred for 5 min at room temperature. The polymerization was then carried out at the temperature specified in Table 1 (80-110 °C) and 200 rpm for t = 24 h and then quenched by adding pyridine (ten times the amount of the

[0104] initiator) and cooled to room temperature.

[0105] The parameters used in production are summarized in Table 1.

[0106] Table 1

[0107] Monomers

[0108] The substances used are listed in Table 2.

[0109] Table 2

[0110] B. Analysis

[0111] To determine the conversion of epoxy groups, samples (0.40 mL each) were taken through the septum with a syringe both before the start of polymerization and at set intervals and mixed with a 6.25% solution of pyridine in ethanol (40 pL).

[0112] The molecular weight distribution of the resulting polymer solution was determined by GPC. The determination was carried out using degassed THF as the mobile phase, a 100 pL injection volume, and a sample concentration of 1 g / L at a flow rate of 0.5 mL / min at 25 °C on a system consisting of a PSS-SECcurity 1260 HPLC pump, a PSS SDV 10 pm ID 8 mm x 50 mm guard column, and a PSS SDV 10 pm 10 3 Ä ID 8 mm x 300 mm, one PSS SDV 10 pm 10 5 Ä ID 8 mm x 300 mm, one PSS SDV 10 pm 10 7ID 8 mm x 300 mm and a SECcurity differential refractometer detector (RI). The data were recorded and evaluated using the PSS - WinGPC UniChrome version 8.33 software. Calibration was performed using polystyrene standards, which are universally converted into a poly(methyl methacrylate) calibration using the Mark Houwink coefficients K and a. Obtaining a GPC result simultaneously fulfills the solubility criterion of the polyepoxides according to the invention. This demonstrates that the polyepoxides present here are uncrosslinked. It is clear to the expert that, for a meaningful result, at least 95 wt.% of the sample to be analyzed must be dissolved in the respective mobile phase, in this case THF, during sample preparation.

[0113] The epoxy conversion was determined by FTIR or NMR, depending on the substance observed.

[0114] To quantify the time-dependent epoxy monomer conversion, the shrinkage of the epoxy band in the IR spectrum was used for Monol. For this purpose, the integral ratio of the epoxy band (778 to 812 cm-1) and the carbonyl band (1650 to 1800 cm-1) was calculated. The integral ratio before the start of polymerization served as a reference for a conversion of 0%. The time-dependent epoxy monomer conversion U(t) was thus obtained using the following relationship: 100%

[0115] To quantify the time-dependent epoxy monomer conversion of Mono2, the growth of the polyether band in the IR spectrum was used. For this purpose, the integral ratio of the polyether region (996 to 1115 cm -1 ) and carbonyl band (1660 to 1770 cm' 1 ) was formed. The time-dependent epoxy monomer conversion U(t) was determined using a correlation equation created by calibration with conversion determined by NMR spectroscopy:

[0116] The Fourier transform infrared spectra (FTIR) were recorded on a Bruker Vertex 70 with a platinum diamond ATR unit in the spectral range from 4000 to 400 cm' 1 at a resolution of 2 cm' 1 The OPUS software was used for analysis. 1 H NMR spectra of samples dissolved in CDCh were recorded on a Bruker AVI II (300 MHz) or Bruker AVII+ (500 MHz) with a 10 mm BBO / 5 mm BBFO probe head. TopSpin software was used for analysis.

[0117] The results obtained are summarized in Table 3.

[0118] Table 3

[0119] The GPC results show that uncrosslinked polyepoxides of the invention with advantageous molecular weights can be obtained, and in particular, uncrosslinked polyepoxides of the invention with high molecular weights (cf. Examples E4-E6) can also be obtained. These are particularly outstandingly suitable for formulating reactive pressure-sensitive adhesives. For this purpose, the dissolved polyepoxides of Examples E4 to E6 were formulated with 1,6-hexanediol diacrylate (HDDA) in a ratio of 90 wt. % to 10 wt. %, based on the solids content, spread by methods known to those skilled in the art, and dried. The films produced all exhibited advantageous pressure-sensitive adhesive properties.

[0120] The skilled person recognizes the advantageous properties of the polyepoxides of the invention by the easy controllability of the properties via the number (proportion of monomer 2 and / or monomer 3, initiator concentration) and the type (selection of monomer 2 and / or monomer 3) of crosslinking points along the polyepoxide polymer chain. In particular, the skilled person recognizes that the polyepoxides of the invention can be advantageously used for the synthesis of reactive pressure-sensitive adhesives, since the polyepoxide of the invention can first be used to formulate a pressure-sensitive adhesive, which can then be processed into a pressure-sensitive adhesive tape, which can be cured in a further step after application of the pressure-sensitive adhesive tape.

[0121] In contrast, state-of-the-art epoxy adhesives are generally applied and cured in a single step as a fluid formulation. Alternative approaches to epoxy-based pressure-sensitive adhesive tapes based on epoxy-functionalized novolaks or the polymerization of monomeric epoxy compounds or epoxy resins exhibit the disadvantages discussed above, which are readily apparent to those skilled in the art.

Claims

Claims 1. A polyepoxide for use in reactive adhesives, wherein the polyepoxide is preparable by polymerizing a monomer composition comprising, based on the mass of the monomer composition: i) one or more first monomers in a combined mass fraction of 50% or more, wherein the first monomers are selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), wherein R represents a linear or branched alkyl group having 1 to 30 C atoms, and ii) one or more second monomers in a combined mass fraction of 1% or more, wherein the second monomers are selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), wherein R represents a linear or branched organic radical having 1 to 30 C atoms, which comprises at least one reactive functional group, and / or iii) one or more third monomers in a combined mass fraction of 1% or more,wherein the third monomers are selected from the group consisting of multiepoxy-functional monomers of the formula (I), wherein R represents a linear or branched organic radical having 2 to 30 C atoms which comprises at least one epoxy group, wherein the formula (I): corresponds.

2. The polyepoxide of claim 1, wherein the monomer composition comprises second monomers.

3. Polyepoxide according to one of claims 1 or 2, wherein the monomer composition comprises third monomers.

4. Polyepoxide according to any one of claims 1 to 3, wherein the polyepoxide has a gel content of 10% or less by mass in toluene.

5. Polyepoxide according to one of claims 1 to 4, wherein the polyepoxide has a weight-average molecular weight M w (GPC) of 500000 g / mol or less.

6. Polyepoxide according to any one of claims 1 to 5, wherein the polyepoxide is preparable by polymerization of the monomer composition initiated by a cationic initiator.

7. Polyepoxide according to any one of claims 1 to 5, wherein the polyepoxide is preparable by polymerization of the monomer composition, which is carried out in a solvent.

8. Polyepoxide according to any one of claims 1 to 7, wherein the polyepoxide is preparable by polymerization of the monomer composition, which is carried out at a temperature in the range of 50 to 150 °C 9. A curable adhesive composition comprising a polyepoxide according to any one of claims 1 to 8.

10. Adhesive tape comprising a curable adhesive composition according to claim 9.

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