Uncrosslinked polyepoxides and adhesives comprising such polyepoxides

Abstract

The present invention relates to a polyepoxide for a reactive adhesive, in which 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 monomer is selected from the group consisting of cycloaliphatic monoepoxy functional monomers of formula (I) wherein R represents a linear or branched alkyl group having 1 to 30 C atoms, and ii) a combined mass fraction of 1% or more of one or more second monomers wherein the second monomer is selected from the group consisting of cycloaliphatic monoepoxy functional monomers of formula (I) wherein R represents a linear or branched alkyl group having 1 to 30 C atoms, wherein R represents a linear or branched organic group having 1 to 30 C atoms comprising at least one reactive functional group, and / or iii) a combined mass fraction of 1% or more of one or more third monomers wherein the third monomers are selected from the group consisting of polyepoxy functional monomers of formula (I), wherein R represents a linear or branched organic group having 2 to 30 C atoms comprising at least one epoxy group, wherein formula (I) is: # imgabs0 #

Description

Technical Field

[0001] The invention relates to polyepoxides for reactive adhesives, corresponding curable adhesives and adhesive tapes comprising such curable adhesives. In addition, methods for producing corresponding polyepoxides and the use of corresponding adhesive tapes for bonding two or more components are disclosed. Background Art

[0002] The joining of individual components is one of the core methods of manufacturing technology. In addition to other methods such as welding and soldering, bonding, i.e. joining using adhesives, is now particularly important. As an alternative to the use of formless adhesives (which are applied, for example, from tubes), so-called adhesive tapes are used.

[0003] In particular, pressure-sensitive adhesive tapes are known in everyday life, wherein a pressure-sensitive adhesive ensures a bonding effect which is permanently tacky and adhesive under normal ambient conditions. The corresponding pressure-sensitive adhesive tapes can be applied to a substrate by pressure and remain adhered there, but can later be removed in a more or less residue-free manner.

[0004] However, another type of adhesive tape is also very important for use in industrial manufacturing technology. In these adhesive tapes, which are sometimes also referred to as reactive adhesive tapes, curable adhesives or reactive adhesives are used. The corresponding curable adhesive has not yet reached its maximum crosslinking degree under the expected application state and can be cured by external influences, such as initiating polymerization in the curable adhesive and thus increasing the crosslinking degree. In this case, the mechanical properties of the adhesive cured at this moment change, wherein in particular viscosity, surface hardness and strength increase. The curability of the corresponding curable adhesive is usually achieved by using polymerizable compounds, in particular crosslinkable monomers, oligomers or polymers.

[0005] An important class of polymerizable compounds for reactive adhesive tapes is epoxides, which are sometimes also called epoxy resins, many of which are used on a large scale today, being obtained by reacting mono- or di-ols with epichlorohydrin.

[0006] Although the epoxy compounds known from the prior art have the most favorable reactivity in the curing reaction, these compounds are considered disadvantageous for some areas of application due to their physicochemical properties. In particular, many commercially relevant epoxy compounds are liquid, which in many cases functionally limits the suitability in adhesives, since the cohesion of the adhesive should not be reduced too much. This is particularly relevant in the following cases: also for reactive adhesive tapes, a certain degree of pressure-sensitive adhesiveness should be achieved before curing for optimal processability at the end user, so that the reactive adhesive tape can be removed essentially without residue before curing if necessary, for example when the adhesive tape has been incorrectly applied.

[0007] In view of the above embodiments, in the field of adhesive technology, it is of interest to obtain epoxy compounds which have the crosslinkability required for curing but have sufficient solubility and favorable rheological properties, in particular increased viscosity, and which can accordingly be used to produce high-performance reactive adhesives with favorable cohesion.

[0008] In this regard, the prior art discloses the use of epoxy-functional novolacs in which an increased molecular weight is formed from the backbone of a phenolic resin, wherein these compounds, ie compounds whose polymer structure differs significantly from that achievable by polymerization of epoxides, are considered disadvantageous for certain applications.

[0009] For this reason, alternative methods are based on the so-called initial polymerization (preliminary polymerization, Anpolymerisieren) of monomeric epoxy compounds, that is, limited polymerization or oligomerization, which increases the molar mass of the obtained compound, but does not lead to the crosslinking of the monomeric epoxy compounds so that they are chemically completely or too strongly crosslinked. For example, a corresponding method is disclosed in EP 3101047 A1. However, the methods known in the prior art are considered to be disadvantageous in many cases, because the required initial polymerization is usually not easy to control. This is especially because the epoxy compounds used for subsequent reactive adhesives should usually have the ability to crosslink with each other and therefore contain two or more epoxy groups. Therefore, during the initial polymerization, for example, due to local inhomogeneities in the initiator concentration, undesirable crosslinking is easily caused, which leads to, for example, the formation of insoluble precipitates. In addition, these settings reduce the concentration of reactive epoxy groups, so that the possibility of reactivity and particularly controllable regulation of reactivity is considered to be insufficient in many cases.

[0010] Further information on the technical background in the field of epoxy-based adhesives can be found in "Epoxy Adhesive Formulations"; Edward Petrie; 2005, McGraw-Hill Professional; ISBN 978-0-07-145544-2. Summary of the invention

[0011] The main object of the present invention is to eliminate or at least reduce the above-mentioned disadvantages of the prior art.

[0012] In particular, it was an object of the present invention to provide non-crosslinked (uncrosslinked) epoxy compounds having advantageous rheological properties which can be used in high-performance reactive adhesives having advantageous cohesion.

[0013] In this context, it was an object of the present invention to provide epoxy compounds which have excellent processability during the preparation of reactive adhesives.

[0014] Furthermore, it was an object of the present invention that the epoxy compounds to be provided should have excellent reactivity in the crosslinking reaction, wherein a particular object of the present invention was that the reactivity should be particularly precisely controllable and adaptable to the respective application requirements.

[0015] Furthermore, it is a supplementary object of the present invention to provide curable adhesives comprising epoxy compounds to be provided and reactive adhesive tapes based thereon.

[0016] A secondary object of the present invention is to provide a process for producing the corresponding non-crosslinked epoxy compounds and the use of corresponding reactive adhesive tapes.

[0017] The inventors of the present invention have now found that, unexpectedly, the above objects can be achieved by polyepoxides obtainable by copolymerization of specific types of cycloaliphatic monoepoxy-functional monomers with specific cycloaliphatic monoepoxy-functional monomers comprising reactive functional groups other than epoxy groups and / or with specific cycloaliphatic polyepoxy-functional monomers, as defined in the claims.

[0018] This specific combination surprisingly makes it possible to obtain particularly effective non-crosslinked epoxy compounds with advantageous and easily adjustable rheological properties, which allow favorable cohesion to be set in the curable adhesive, wherein the polyepoxides, due to their sufficient solubility in conventional solvents, can be processed very well, in particular when mixed with the other components of the curable adhesive, and allow reliable curing of the curable adhesive in the final application.

[0019] Here, the reactivity of the polyepoxide in the subsequent crosslinking by the cycloaliphatic epoxy-functional monomers with reactive functional groups is advantageously controllable. Here, in particular, the use of cycloaliphatic monoepoxy-functional monomers comprising reactive functional groups other than epoxy groups allows a particularly controlled introduction of reactive groups into the polyepoxide, which are available for the subsequent chemical crosslinking without causing undesired crosslinking during the initial polymerization of the epoxide monomers, which in particular also makes the high concentration of reactive groups in the polyepoxide accessible, which reactive groups can be precisely controlled according to the design by the curing mechanism selected for the curable adhesive, for example in the further crosslinking of the adhesive in the adhesive tape and / or in the subsequent curing process in the final application. However, it is advantageous that in the subsequent adhesive application, chemical bonds can also be formed with the substrate via the reactive groups.

[0020] The above objects are therefore achieved by the subject matter of the invention as defined in the claims. Preferred embodiments according to the invention are given by the dependent claims and the following embodiments.

[0021] Those embodiments which are hereinafter referred to as preferred are combined in particularly preferred embodiments with features of further embodiments which are referred to as preferred. Therefore, very particularly preferred are combinations of two or more embodiments which are hereinafter referred to as particularly preferred. It is also preferred that the features of one embodiment which is referred to as preferred to a certain extent are combined with one or more other features of further embodiments which are referred to as preferred to a certain extent. The features of the preferred curable adhesives, adhesive tapes, methods and uses are given by the features of the preferred polyepoxides.

[0022] For the following elements, for example, for mono-epoxy-functional or poly-epoxy-functional monomers, both the specific amount or fraction of the element and the preferred embodiment of the element are disclosed, and in particular the specific amount or fraction of the element that is preferably designed is also disclosed. In addition, it is disclosed that in the corresponding specific total amount or total fraction of the element, at least a part of the element can be preferably designed, and in particular it is also disclosed that the preferably designed element can be present in a specific amount or fraction within the specific total amount or total fraction.

[0023] The present invention relates to polyepoxides for reactive adhesives, wherein the polyepoxides can be prepared by polymerizing a monomer composition, the monomer composition comprising, based on the mass of the monomer composition:

[0024] i) one or more first monomers in a combined mass fraction of 50% or more, wherein the first monomer is selected from alicyclic monoepoxy-functional monomers of formula (I), wherein R represents a linear or branched alkyl group having 1 to 30 C atoms, and

[0025] ii) one or more second monomers in a combined mass fraction of 1% or more, wherein the second monomer is selected from alicyclic monoepoxy-functional monomers of formula (I), wherein R represents a linear or branched organic group having 1 to 30 C atoms including at least one reactive functional group, and / or

[0026] iii) one or more third monomers in a combined mass fraction of 1% or more, wherein the third monomer is selected from a polyepoxy-functional monomer of formula (I), wherein R represents a linear or branched organic group having 2 to 30 C atoms including at least one epoxy group,

[0027] Wherein formula (I) is:

[0028]

[0029] The polyepoxide according to the invention is a copolymer prepared or preparable by polymerization from a specific monomer composition. According to the understanding and conventional settings of a person skilled in the art, it is advantageous to define such a copolymer by the manufacturing method or the starting materials used for its manufacture, since it is essentially impossible to ultimately define the corresponding material in a different way in its entirety.

[0030] According to conventional arrangements in the technical field, manufacturability is defined here in relation to the monomer composition, which, according to the understanding of the skilled person, includes all monomer components that are converted into monomer units of the polyepoxide during the polymerization process. Therefore, other components that are optionally present in the reaction mixture during the polymerization process but are not introduced into the polyepoxide during the polymerization process, such as solvents, catalysts or initiators, do not belong to the monomer composition.

[0031] According to the understanding of the skilled person, the components of the monomer composition defined above are each used as "one or more". The term "one or more" refers to the chemical nature of the corresponding monomers in the usual way in the industry, rather than the amount of its substance. For example, the monomer composition may only include methyl 3,4-epoxycyclohexylcarboxylate as the first monomer, which means that the monomer composition includes a plurality of corresponding molecules.

[0032] In conventional manner, the mass fractions of components in a monomer composition are expressed as the combined mass fraction of one or more monomers, thereby indicating the mass fractions of the correspondingly designed monomers which together meet the corresponding criteria, wherein in each case the mass of the monomer composition forms the reference system.

[0033] Those skilled in the art adapt the polymerization method for polymerization to the monomer present in the monomer composition, that is, the required structure of the functional group and polyepoxide that are particularly available. In practice, polymerization basically comprises cationic polymerization at least in part of the steps under all circumstances, because this is particularly suitable for the polymerization of epoxy compounds. The method for cationic polymerization (wherein the active center of chain replication is formed by cation) is well known to those skilled in the art based on its general expertise, and is one of the methods established in the field of epoxy compounds. The preferred embodiment of cationic polymerization is disclosed hereinafter. However, in particular, in the presence of the second monomer with the reactive functional group of non-epoxy group, the preparation may also include the other polymerization step using other polymerization methods in addition. However, in practice, considering high epoxy concentration, these alternative polymerization methods will only make very little contribution usually, so that the following polyepoxide according to the present invention is preferred, and it can be manufactured using cationic polymerization completely basically.

[0034] The above-mentioned provision that the polyepoxide is suitable for reactive adhesives, i.e. as a reactive component of reactive adhesives, means to the person skilled in the art that it is a non-crosslinked polyepoxide which can be further crosslinked in reactive adhesives and has physicochemical properties which allow suitability in reactive adhesives, in particular with regard to solubility in conventional solvents. Crosslinked polyepoxides, in which polymerization leads to the formation of a network and are therefore substantially insoluble in most solvents, are mainly thermosetting materials and do not meet this suitability.

[0035] According to the skilled person, the term "non-crosslinked" here relates to chemical crosslinking, i.e. the individual copolymer chains are covalently linked to one another to form a network, but not to any physical crosslinking of the copolymer chains, for example by entanglement, phase separation or crystallization.

[0036] The skilled person understands that non-crosslinked polyepoxides are not necessarily linear, but can also have copolymer chains with branches, especially when the monomer composition includes a third monomer. Although the transition from branched copolymer chains to a network of crosslinked polyepoxides seems vague in theory, it is relatively irregular for a skilled person to determine the non-crosslinked state or suitability for use in reactive adhesives in practice, where he can determine this, for example, based on rheological properties or their temperature dependence or by simple solubility tests.

[0037] Based on typical practical evaluation criteria for determining a sufficiently uncrosslinked state, the properties of the polyepoxides according to the invention can be specified (specified) according to the inventor's evaluation, wherein in any case there are suitability or "non-crosslinked" properties based on the crosslinked state for reactive adhesives. These are given below and relate to properties of solubility or gel fraction and weight-average molecular weight. On the contrary, in these cases, the implementation of the polyepoxides according to the invention in this form is also preferred due to the good suitability for reactive adhesives.

[0038] In this respect, preference is firstly given to polyepoxides 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, benzene (petroleum spirit), toluene, ethanol, isopropanol, ethyl acetate and diethyl ether. In this respect, preference is given to polyepoxides according to the invention, wherein the mass-related gel fraction of the polyepoxide is 10% or less, preferably 5% or less. The mass-related gel fraction is defined as the ratio of the fraction of the polymer that is insoluble in toluene, acetone or methyl ethyl ketone, preferably insoluble in toluene, at room temperature to the total mass of the polymer. For this purpose, a carefully dried solvent-free polymer sample is enclosed in a nonwoven bag (Tyvek nonwoven) made of polyethylene. The weight fraction of the polymer that is insoluble in the solvent can be determined from the difference in the sample weight before extraction and after extraction at 23° C. by a solvent (i.e., by toluene, acetone or methyl ethyl ketone, preferably by toluene) for 72 hours. Here, the extractant is renewed after 24 hours and 48 hours. The sample mass remaining in the bag gives the mass-based gel fraction of the polymer, which is also referred to as the gel value. This value is given here as the average value (%) of three determinations.

[0039] As regards the fully uncrosslinked state, the following polyepoxides according to the invention are also preferred, wherein the copolymer chains in the polyepoxide have 10 7 g / mol or lower, preferably 10 6 In this respect, additionally or alternatively, polyepoxides according to the invention are preferred, wherein the polyepoxides have a weight average molecular weight Mw (GPC) of 500,000 g / mol or less, preferably 250,000 g / mol or less, particularly preferably 125,000 g / mol or less, very particularly preferably 50,000 g / mol or less, and / or wherein the polyepoxides have a weight average molecular weight Mw (GPC) in the range of 1,000 to 300,000 g / mol, preferably in the range of 2,000 to 200,000 g / mol, particularly preferably in the range of 3,000 to 100,000 g / mol, wherein a range of 1,000 to 10,000 g / mol or alternatively 10,000 to 100,000 g / mol is particularly preferred.

[0040] Weight average molecular weight M w The figures here relate to the determination by gel permeation chromatography (GPC). The determination was carried out using degassed THF as eluent, an injection volume of 100 μl 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 SECecurity 1260 HPLC pump, a PSS SDV 10 μm ID 8 mm x 50 mm precolumn, a PSS SDV 10 μm ID 8mm x 300mm, PSSSDV 10μm ID 8mm x 300mm, PSS-SDV 10μm ID 8mm x 300mm and SECurity differential refractometer detector (RI). The skilled person is aware that during sample preparation, in order to obtain meaningful results, at least 95 wt. % (weight percent) of the sample to be examined is dissolved in the corresponding eluent (here THF).

[0041] The data were recorded and evaluated using the software PSS-WinGPC UniChrome version 8.33. The calibration was carried out using polystyrene standards which were usually converted to poly(methyl methacrylate) calibration by means of the Mark Houwink coefficients K and α.

[0042] The polyepoxides according to the invention are preferred, wherein the polyepoxide is a thermoplastic solid at 25° C. and a pressure of 100 kPa.

[0043] According to the above definition, various monomeric epoxy compounds are used in the monomer composition. According to the understanding of the technician, epoxy compounds are compounds with at least one oxirane group. The monomers used as the first, second and third monomers are each alicyclic, which means that they include at least one ring system in their structure, but do not include an aromatic ring system. The monomers used as the first, second and third monomers each have the same basic structure described by formula (I), but are different in terms of the corresponding radical R:

[0044]

[0045] The first monomer has no reactive functional groups in the radical R, i.e., neither epoxy groups nor other reactive functional groups. In the case of the first monomer, however, the radical R is an alkyl group, which in the usual manner can be linear or branched, wherein linear groups are quite preferred. According to the inventors' estimation, in particular a large mass fraction of these monoepoxy-functional monomers, which also have no reactive functional groups in the radical R, enables the advantageous properties of the polyepoxides according to the invention to be achieved and, by means of said mass fraction, enables the acquisition of non-crosslinked polyepoxides which are accordingly particularly suitable for reactive adhesives.

[0046] In this respect, the inventors have succeeded in specifying particularly preferred embodiments for the first monomer, wherein starting from the cycloaliphatic monoepoxy-functional monomers of the formula (I) used according to the invention, in which R represents a linear or branched, preferably linear alkyl group having 1 to 30 C atoms, according to the inventors' estimation, particularly advantageous polyepoxides according to the invention can be obtained. That is, polyepoxides according to the invention are preferred in which the first monomer is selected from the cycloaliphatic monoepoxy-functional monomers of the formula (I), in which 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, wherein R particularly preferably represents a methyl, ethyl or propyl group. Polyepoxides according to the invention are particularly preferred in which the first monomer is methyl 3,4-epoxycyclohexylcarboxylate, and / or in which the monomer composition comprises methyl 3,4-epoxycyclohexylcarboxylate, preferably in a mass fraction of 50% or more, particularly preferably 70% or more, very particularly preferably 90% or more, based on the combined mass fraction of the first monomers.

[0047] The second monomer is also a monoepoxy-functional monomer, but, unlike the first monomer, has at least one reactive functional group in the radical R. The term "reactive functional group" is clear here to the person skilled in the art, who also understands that such reactive functional groups in the monoepoxy-functional monomers according to formula (I) cannot themselves be epoxy groups, since formula (I) already has epoxy groups. The inventors have also succeeded in specifying particularly preferred embodiments for the second monomer, wherein, according to the inventors' assessment, starting from alicyclic monoepoxy-functional monomers of formula (I) (in which R represents a linear or branched, preferably linear, organic radical having 1 to 30 C atoms and comprising at least one reactive functional group), particularly advantageous polyepoxides according to the invention can be obtained and are particularly effectively suitable for targeted subsequent crosslinking via the corresponding functional groups.

[0048] In this respect, preference is firstly given to polyepoxides according to the invention in which the second monomer is selected from cycloaliphatic monoepoxy-functional monomers of formula (I), in which R represents a linear or branched, preferably branched, organic radical having 2 to 20 C atoms, preferably having 3 to 10 C atoms, comprising at least one reactive functional group. Additionally or alternatively, preference is given to polyepoxides according to the invention in which the reactive functional group is selected from alkoxysilane groups, hydroxyl groups, amine groups, isocyanate groups, carboxylic acid groups, carboxylic anhydrides and C═C double bonds, preferably from alkoxysilane groups, hydroxyl groups, carboxylic acid groups, carboxylic anhydrides and C═C double bonds, particularly preferably from hydroxyl groups and C═C double bonds, and / or in which the second monomer is selected from acrylates, methacrylates and vinyl ethers, preferably from acrylates and methacrylates. The polyepoxides according to the invention are particularly preferred, 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 70% or more, very particularly preferably 90% or more, based on the combined mass fraction of the second monomer.

[0049] With regard to the significant crosslinkability, according to the inventors' estimation, depending on whether different reactivity in the side chain is desired, a second monomer with multiple reactive functional groups, which may be identical or different, may be implemented. Therefore, the following polyepoxides according to the invention are preferred, wherein the second monomer comprises two or more reactive functional groups, in particular similar reactive functional groups.

[0050] In addition or as an alternative to the second monomer, the subsequent crosslinkability of the polyepoxides according to the invention can also be achieved by means of third monomers, wherein, unlike the second monomer, these monomers contain at least one epoxy group in the radical R and are therefore polyepoxide-functional monomers.

[0051] Here, according to the inventors' estimation, starting from polyepoxy-functional monomers of the formula (I) in which R represents a linear or branched, preferably linear, organic radical having 2 to 30 C atoms comprising at least one epoxide group, the following polyepoxides according to the invention are preferred, in which the third monomer is selected from polyepoxy-functional monomers of the formula (I) in which R represents 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, comprising at least one epoxide group.

[0052] Polyepoxides according to the invention are preferred wherein the epoxy groups are epoxide groups or oxetane groups, preferably epoxide groups, and / or wherein the third monomer is selected from diepoxide-functional monomers.

[0053] Although the group R of the third monomer may in theory also include further reactive functional groups as disclosed above for the second monomer, it is preferred that the third monomer does not include further reactive functional groups in the group R other than one or more epoxy groups.

[0054] The polyepoxides according to the invention are particularly preferred, wherein the third monomer is a diepoxycyclohexyl derivative, preferably (3,4-epoxycyclohexyl)methyl-3,4-epoxycyclohexylcarboxylate, and / or wherein the monomer composition comprises a diepoxycyclohexyl derivative, preferably (3,4-epoxycyclohexyl)methyl-3,4-epoxycyclohexylcarboxylate, preferably in a mass fraction of 50% or more, particularly preferably 70% or more, very particularly preferably 90% or more, based on the combined mass fraction of the third monomers.

[0055] In the context of the present invention, the term "monomer" is widely understood and is mainly used to clearly define the starting compound for polyepoxide copolymers. This term represents that these monomers should be introduced into the copolymer. It is understood by those skilled in the art that the term "monomer" also includes low molecular weight compounds that can be regarded as oligomers of one or more monomers. According to the understanding of the technician, this is advantageous because oligomerization can occur unconsciously and the oligomer obtained can be manufactured by the corresponding monomers in any case in the sense of the above definition, so that the existence of oligomers (it can be said to be an intermediate stage) will not affect the manufacturability of manufacturing polyepoxides according to the present invention from the monomer composition. In this context, the following polyepoxide according to the present invention is preferred, wherein the first monomer and / or the second monomer, preferably the first monomer and the second monomer have a molecular weight (molar mass) in the range of 75 to 1000g / mol, preferably in the range of 100 to 500g / mol, wherein the molecular weight is particularly preferably in the range of 100 to 200g / mol or in the range of 200 to 350g / mol or in the range of 350 to 500g / mol. Additionally or alternatively, polyepoxides according to the invention are preferred in which the molecular weight of the third monomer is in the range of 75 to 1000 g / mol, preferably in the range of 150 to 500 g / mol, wherein the molecular weight is particularly preferably in the range of 150 to 250 g / mol or in the range of 250 to 350 g / mol or in the range of 350 to 500 g / mol.

[0056] As described above, according to the inventors' estimation, in particular, the high minimum fraction of the first monomer and the specific basic structure of the cycloaliphatic epoxy-functional monomer according to formula (I) open up the possibility of obtaining advantageous non-crosslinked polyepoxides. Based on this, by changing the mass ratios in the monomer composition precisely according to the respective requirements and the desired crosslinking behavior, the physicochemical properties of the polyepoxides according to the invention can be advantageously adjusted, wherein the fraction of reactive side chains with epoxy groups or other reactive functional groups can be increased as required.

[0057] Since this opens up different crosslinking chemistries for essentially all embodiments, it is expressly preferred that the monomer composition comprises at least a small amount of a second monomer, wherein in particular, according to the inventors' assessment, a combination of a second and a third monomer is also particularly advantageous, since in this case, in the case of non-epoxy functionalities present in the polyepoxide, branching can be achieved by the third monomer, so that the rheological properties of the polyepoxide according to the invention can be optimized.

[0058] In this context, the inventors have succeeded in specifying mass ratios and mass fractions of the various monomers with which, in their estimation, particularly high-performance polyepoxides according to the invention can be obtained.

[0059] Firstly, in this regard, preferred ranges can be determined in each case for the mass fractions of the respective monomers. Polyepoxides according to the invention are preferred in practice in which 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. Polyepoxides according to the invention are also preferred in which the combined mass fraction of the first monomers is in the range of 50 to 99%, preferably in the range of 55 to 98%, particularly preferably in the range of 60 to 95%, very particularly preferably in the range of 65 to 90%, based on the mass of the monomer composition. In this regard, in order to adapt to the requirements of the respective application purpose, polyepoxides according to the invention are preferred in which the combined mass fraction of the first monomers is in the range of 70 to 80% or in the range of 80 to 90% or in the range of 90 to 95%, based on the mass of the monomer composition.

[0060] Regarding the second monomer, the polyepoxide according to the invention is preferred, wherein the combined mass fraction of the second monomer is 2% or more, preferably 5% or more, particularly preferably 10% or more, based on the mass of the monomer composition. In this regard, the polyepoxide according to the invention is also preferred, wherein the combined mass fraction of the second monomer is in the range of 1 to 40%, preferably in the range of 2 to 30%, particularly preferably in the range of 5 to 20%, based on the mass of the monomer composition. Again, in order to adapt to the requirements of various application purposes, the polyepoxide according to the invention is preferred, wherein the combined mass fraction of the third monomer is in the range of 1 to 10%, or in the range of 10 to 35%, or in the range of 35 to 49%, based on the mass of the monomer composition.

[0061] As described above, the polyepoxide according to the invention is preferred, wherein the monomer composition comprises the second monomer and the third monomer, preferably in a mass ratio in the range of 10:1 to 1:10, particularly preferably in a mass ratio in the range of 5:1 to 1:5, very particularly preferably in a mass ratio in the range of 2:1 to 1:2. In addition or alternatively, the polyepoxide according to the invention is particularly preferred, wherein the combined mass fraction of the second monomer and the third monomer is 2% or more, preferably 4% or more, particularly preferably 10% or more, based on the mass of the monomer composition, and / or wherein the combined mass fraction of the second monomer and the third monomer is in the range of 2 to 40%, preferably in the range of 4 to 30%, particularly preferably in the range of 10 to 20%, based on the mass of the monomer composition. For different application scenarios, additionally or alternatively, the following polyepoxides according to the invention are preferred, in which the combined mass fraction of the second monomer and the third monomer is in the range of 1 to 5% or in the range of 5 to 20% or in the range of 20 to 40%, because in these ranges networks of different densities can be obtained in the crosslinking, with which the application technology properties can be particularly well adapted to the required requirements, in particular with regard to pressure-sensitive adhesiveness and performance as a structural adhesive.

[0062] As described above, the polyepoxide according to the invention is preferred, wherein the monomer composition comprises the second monomer and the third monomer, preferably in a mass ratio in the range of 10:1 to 1:10, particularly preferably in a mass ratio in the range of 5:1 to 1:5, very particularly preferably in a mass ratio in the range of 2:1 to 1:2. In addition or alternatively, the polyepoxide according to the invention is particularly preferred, wherein the combined mass fraction of the second monomer and the third monomer is 2% or more, preferably 4% or more, particularly preferably 10% or more, based on the mass of the monomer composition, and / or wherein the combined mass fraction of the second monomer and the third monomer is in the range of 2 to 40%, preferably in the range of 4 to 30%, particularly preferably in the range of 10 to 20%, based on the mass of the monomer composition.

[0063] The person skilled in the art understands that in each case, preference is also given to polyepoxides according to the invention in which the presence of a second monomer or a third monomer is mandatory. On this basis, preference is given to polyepoxides according to the invention in which the first monomer in the monomer composition is predominantly, preferably exclusively, combined with the second monomer or the third monomer, and / or in which the monomer composition does not comprise a third monomer or does not comprise a second monomer.

[0064] In this context, preference is given to polyepoxides according to the invention in which the monomer composition comprises the first monomer and the second monomer, preferably in a mass ratio in the range of 1:1 to 99:1, particularly preferably in a mass ratio in the range of 1.5:1 to 49:1, very particularly preferably in a mass ratio in the range of 2.5:1 to 9:1. Additionally or alternatively, preference is given to polyepoxides according to the invention in which the combined mass fraction of the first monomer and the second monomer 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.

[0065] In this context, alternatively, the polyepoxide according to the invention is preferred, wherein the monomer composition comprises the first monomer and the third monomer, preferably in a mass ratio in the range of 1:1 to 99:1, particularly preferably in a mass ratio in the range of 1.5:1 to 49:1, very particularly preferably in a mass ratio in the range of 2.5:1 to 9:1. Additionally or alternatively, the polyepoxide according to the invention is preferred, wherein the combined mass fraction of the first monomer and the third monomer 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.

[0066] Although in principle further monomers other than the first, second or third monomer can be provided in the monomer composition, in order to obtain particularly potent polyepoxides, according to the inventors' estimation, it is explicitly preferred to form the polyepoxides according to the invention as far as possible from the corresponding specific epoxides. Therefore, polyepoxides according to the invention are preferred in which the combined mass fraction of the first monomer, the second monomer and the third monomer is 80% or more, preferably 90% or more, particularly preferably 95% or more, based on the mass of the monomer composition, and / or in which the combined mass fraction of the first monomer, the second monomer and the third monomer is in the range of 60 to 99%, preferably in the range of 65 to 98%, particularly preferably in the range of 70 to 95%, based on the mass of the monomer composition.

[0067] As mentioned above, the monomer composition may also include further monomers, which may be particularly advantageous for adjusting the physicochemical properties. In this context, polyepoxides according to the invention are preferred in which the monomer composition includes 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 of 1 to 45%, preferably in the range of 2 to 40%, particularly preferably in the range of 5 to 35%, based on the mass of the monomer composition.

[0068] As regards the further monomers, preference is given to using diepoxy-functional monomers which are not the third monomer. In this regard, polyepoxides according to the invention are preferred in which the monomer composition comprises at least one diepoxy-functional monomer selected from diepoxy 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.

[0069] In an advantageous embodiment, the polyepoxide comprises at least one oxetane monomer, in particular a polyfunctional oxetane monomer, as an additional monomer, since the resulting "spacers" between the ether groups in the polyepoxide are longer. Accordingly, the following polyepoxide according to the invention is preferred, wherein the monomer composition comprises at least one oxetane monomer, preferably a polyepoxy-functional oxetane monomer, wherein the oxetane monomer is preferably not the third monomer, wherein the oxetane monomer is particularly preferably selected from (3-ethyloxetane-3-yl)methanol and 3,3'-[oxybis(methylene)]bis(3-ethyloxetane), wherein the combined mass fraction of all oxetane monomers other than the third monomer is preferably in the range of 10 to 40%, particularly preferably in the range of 10 to 20% or in the range of 20 to 30% or in the range of 30 to 40%, based on the mass of the monomer composition. In a particularly preferred embodiment, in addition to one or more epoxy groups, the oxetane monomer further comprises one or more further reactive functional groups, preferably those as described above for the second monomer.

[0070] Furthermore, for certain application purposes, it is advantageous to add vinyl ethers to the monomer composition, which can also be polymerized by cationic polymerization. Therefore, the following polyepoxides according to the invention are preferred, wherein the monomer composition comprises at least one vinyl ether monomer, wherein the vinyl ether monomer is preferably not the second monomer or the third monomer, wherein the combined mass fraction of all vinyl ether monomers that are not the second monomer or the third monomer is preferably in the range of 10 to 40%, particularly preferably in the range of 10 to 20% or in the range of 20 to 30 or in the range of 30 to 40%, based on the mass of the monomer composition, and / or wherein the vinyl ether monomer has a molecular weight in the range of 60 to 1000 g / mol, preferably in the range of 80 to 500 g / mol, wherein the molecular weight is particularly preferably in the range of 80 to 200 g / mol or in the range of 200 to 350 g / mol or in the range of 350 to 500 g / mol.

[0071] The inventors have succeeded in identifying particularly advantageous production conditions for the production of polymers, with which advantageous non-crosslinked polyepoxides can be reliably obtained. In this respect, due to the high relevance of cationic polymerization, explicit preference is firstly given to polyepoxides according to the invention which can be prepared by polymerization of a monomer composition initiated by a cationic initiator, wherein the cationic initiator is preferably used in an amount fraction (or molar fraction) in the range of 0.005 to 1%, based on the number of epoxide groups in the monomer composition. Additionally or alternatively, polyepoxides according to the invention which are preferably supplied stepwise or continuously are preferred.

[0072] In a preferred embodiment, the initiator is first dissolved in at least one solvent and the initiator solution obtained in this way is added to the monomer composition and the solvent present is optionally metered in. Preferred for dissolving the initiator are organic polar aprotic solvents such as acetone, methyl ethyl ketone, diethyl ketone, dimethyl sulfoxide, N,N-dimethylformamide and acetonitrile, with acetone and methyl ethyl ketone being particularly preferred.

[0073] Cationic initiators are in principle known to the skilled person from the prior art. The polyepoxides according to the invention can be produced particularly advantageously when the cationic initiator is selected from cationic photoinitiators and cationic thermal initiators, wherein latent, thermally activatable cationic initiators (TAGs; so-called "thermal acid generators") are particularly preferred. Therefore, the following polyepoxides according to the invention are preferred, wherein the polyepoxides can be prepared by polymerization of a monomer composition initiated by a cationic thermal initiator or a cationic photoinitiator, particularly preferably by a latent, thermally activatable cationic initiator.

[0074] Suitable TAGs are known to those skilled in the art and are commercially available from a number of suppliers. TAGs comprising a cation selected from the group consisting of: 4-substituted benzylaniline , 4-substituted benzylpyridine , 4-substituted benzyl , S-substituted diphenylsulfonium and substituted arylbenzylsulfonium, preferably 4-substituted benzylaniline .

[0075] TAG can in principle contain any anion, among which weakly coordinating anions such as tetrafluoroborate (BF4 - ), hexafluorophosphate (PF6 - ), hexafluoroantimonate (SbF6 - ), tetrakis(pentafluorophenyl)borate (B(C6F5)4 - ) and trifluoromethanesulfonate (F3CSO3 -) is preferred. Here, trifluoromethanesulfonate (F3CSO3 - ) and hexafluoroantimonate (SbF6 - ) is particularly preferred.

[0076] The combination of TAGs consisting of cations and anions is advantageous, wherein the resulting initiator has an activation temperature in the range of 50°C to 150°C, wherein the technician preferably adjusts the activation energy according to the respective application requirements, wherein in particular the range of 80°C to 120°C is preferred in many cases, to enable polymerization at relatively mild activation temperatures, and still allow well-defined initiation. Typically, the activation temperature of a reactive or chemically activatable adhesive or the activation temperature of the TAG used is determined calorimetrically by differential scanning calorimetry (DSC) according to DIN EN ISO 11357-3:2013-04. For this purpose, about 20 mg of the sample is weighed into an aluminum crucible and introduced into the instrument (instrument: DSC 204F1, Netzsch). Two heating curves are then recorded at a heating rate of 10K / min. The sample is measured in an Al crucible with a perforated cover under a nitrogen atmosphere. The activation of a chemical reaction such as TAG is evident in the thermogram as an exothermic peak. The starting temperature is recorded as the activation temperature. For a peak, this is determined as the intersection of a virtual interpolated baseline with the tangent line at the inflection point at the beginning of the peak (according to DIN EN ISO 11357-1:2010-03). The reaction enthalpy in J / g is obtained from the integration of the curing peak.

[0077] As initiators for the cationic UV-induced curing of epoxy compounds, in particular sulfonium, iodine-based and metallocene systems, which are commercially available from many suppliers. For examples of sulfonium-based cations, reference may be made to the embodiments in US Pat. No. 6,908,722 B1. Examples of anions used as counterions to the above cations include tetrafluoroborate, tetraphenylborate, hexafluorophosphate, perchlorate, tetrachloroferrate, hexafluoroarsenate, hexafluoroantimonate, pentafluorohydroxyantimonate, hexachloroantimonate, tetrakispentafluorophenylborate, tetrakis(pentafluoromethylphenyl)borate, bis(trifluoromethanesulfonyl)amide and tris(trifluoromethanesulfonyl)methyl. In addition, particularly for iodine-based Initiator, conceivable anion also includes chloride, bromide or iodide, although the initiator substantially free of chlorine and bromine is preferred. An effective example of such a system is for example triphenylsulfonium hexafluoroantimonate. Further suitable initiators are disclosed in for example US 3,729,313 A, US 3,741,769 A, US 4,250,053 A, US 4,394,403A, US 4,231,951 A, US 4,256,828 A, US 4,058,401 A, US 4,138,255A and US2010 / 063221 A1.

[0078] Specific examples of sulfonium salts that can be used are triphenylsulfonium hexafluoroarsenate, triphenylsulfonium hexafluoroborate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis(pentafluorobenzyl)borate, methyldiphenylsulfonium tetrafluoroborate, methyldiphenylsulfonium tetrakis(pentafluorobenzyl)borate, dimethylphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, diphenylnaphthylsulfonium hexafluoroarsenate, tritolyl ... Phosphate, methoxyphenyl diphenylsulfonium hexafluoroantimonate, 4-butoxyphenyl diphenylsulfonium tetrafluoroborate, 4-chlorophenyl diphenylsulfonium hexafluoroantimonate, tris(4-phenoxyphenyl)sulfonium hexafluorophosphate, di(4-ethoxyphenyl)methylsulfonium hexafluoroarsenate, 4-acetylphenyl diphenylsulfonium tetrafluoroborate, 4-acetylphenyl diphenylsulfonium tetrakis(pentafluorobenzyl)borate, tris(4-thiomethoxyphenyl)sulfonium hexafluorophosphate, bis(methoxysulfonylphenyl)methylsulfonium hexafluoroantimonate, bis(methoxynaphthyl)methylsulfonium tetrafluoroborate, bis(methoxynaphthyl)methylsulfonium tetrakis(pentafluorobenzyl)borate, bis(carbomethoxyphenyl)methylsulfonium hexafluorophosphate, (4-octyloxyphenyl)diphenylsulfonium tetrakis(3,5-bistrifluoromethylphenyl)borate, tris[4-4-(acetylphenyl)thiophenyl]sulfonium tetrakis(pentafluorophenyl) ) borate, tri(dodecylphenyl)sulfonium tetra(3,5-bis(trifluoromethylphenyl)borate, 4-acetamidophenyldiphenylsulfonium tetrafluoroborate, 4-acetamidophenyldiphenylsulfonium tetra(pentafluorobenzyl)borate, dimethylnaphthylsulfonium hexafluorophosphate, trifluoromethyldiphenylsulfonium tetrafluoroborate, trifluoromethyldiphenylsulfonium tetra(pentafluorobenzyl)borate, phenylmethylbenzylsulfonium hexafluorophosphate, 5-methylthianthrene Hexafluorophosphate, 10-phenyl-9,9-dimethylthioxanthene Hexafluorophosphate, 10-phenyl-9-oxythioxanthene Tetrafluoroborate, 10-phenyl-9-oxythioxanthene Tetrakis(pentafluorobenzyl)borate, 5-methyl-10-oxythianthrene Tetrafluoroborate, 5-methyl-10-oxythianthrene Tetrakis(pentafluorobenzyl)borate and 5-methyl-10,10-dioxythianthrene Hexafluorophosphate.

[0079] Available iodine A specific example of a salt is diphenyl iodide Tetrafluoroborate, di(4-methylphenyl)iodide Tetrafluoroborate, phenyl-4-methylphenyl iodide Tetrafluoroborate, di(4-chlorophenyl)iodide Hexafluorophosphate, dinaphthyl iodide Tetrafluoroborate, bis(4-trifluoromethylphenyl)iodide Tetrafluoroborate, diphenyl iodide Hexafluorophosphate, di(4-methylphenyl)iodide Hexafluorophosphate, diphenyl iodide Hexafluoroarsenate, bis(4-phenoxyphenyl)iodide Tetrafluoroborate, phenyl-2-thienyl iodide Hexafluorophosphate, 3,5-dimethylpyrazolyl-4-phenyl iodide Hexafluorophosphate, diphenyl iodide Hexafluoroantimonate, 2,2'-diphenyliodide Tetrafluoroborate, bis(2,4-dichlorophenyl)iodide Hexafluorophosphate, di(4-bromophenyl)iodide Hexafluorophosphate, di(4-methoxyphenyl)iodide Hexafluorophosphate, di(3-carboxyphenyl)iodide Hexafluorophosphate, bis(3-methoxycarbonylphenyl)iodide Hexafluorophosphate, bis(3-methoxysulfonylphenyl)iodide Hexafluorophosphate, bis(4-acetylaminophenyl)iodide Hexafluorophosphate, di(2-benzothienyl)iodide Hexafluorophosphate, diaryl iodide Tris(trifluoromethanesulfonyl)methyl)diphenyl iodide Hexafluoroantimonate, diaryl iodide Tetrakis(pentafluorophenyl)borate as diphenyl iodide Tetrakis(pentafluorophenyl)borate, [4-2-(hydroxy-n-tetradesiloxy)phenyl]phenyl iodide Hexafluoroantimonate, [4-2-(hydroxy-n-tetradecyloxy)phenyl]phenyl iodide Trifluorosulfonate, [4-2-(hydroxy-n-tetradecyloxy)phenyl]phenyl iodide Hexafluorophosphate, [4-2-(hydroxy-n-tetradecyloxy)phenyl]phenyl iodide Tetrakis(pentafluorophenyl)borate, bis(4-tert-butylphenyl)iodide Hexafluoroantimonate, bis(4-tert-butylphenyl)iodide Hexafluorophosphate, bis(4-tert-butylphenyl)iodide Trifluorosulfonate, bis(4-tert-butylphenyl)iodide Tetrafluoroborate, bis(dodecylphenyl)iodide Hexafluoroantimonate, bis(dodecylphenyl)iodide Tetrafluoroborate, bis(dodecylphenyl)iodide Hexafluorophosphate, bis(dodecylphenyl)iodide Trifluoromethanesulfonate, di(dodecylphenyl)iodide Hexafluoroantimonate, didodecylphenyl iodide Trifluoromethanesulfonate, diphenyl iodide Bisulfate, 4,4'-dichlorodiphenyl iodide Bisulfate, 4,4'-dibromodiphenyl iodide Bisulfate, 3,3'-Dinitrodiphenyl iodide Bisulfate, 4,4'-dimethyldiphenyl iodide Bisuccinimidyl diphenyl iodide Bisulfate, 3-nitrodiphenyl iodide Bisulfate, 4,4'-dimethoxydiphenyl iodide Bis(dodecylphenyl)iodide Tetrakis(pentafluorophenyl)borate, (4-octyloxyphenyl)phenyl iodide Tetrakis(3,5-bis(trifluoromethylphenyl)borate and tolylcumyl)iodide Tetrakis(pentafluorophenyl)borate; and ferrocenium salts (see, e.g., EP 0 542 716 B1) such as n 5 -(2,4-cyclopentadien-1-yl)[1,2,3,4,5,6,9)-(1-methylethyl)phenyl]iron.

[0080] Photoinitiators are usually used alone or as a combination of two or more photoinitiators. When using photoinitiators, a combination with a so-called sensitizer for adapting the activation wavelength of the photoinitiating system to the selected emission spectrum is very helpful, for which reference is made to the literature known to those skilled in the art, for example "Industrial Photoinitiators: A technical guide" 2010 by AW Green.

[0081] When photoinitiators are used, activation by irradiation can be carried out initially, repeatedly or continuously.

[0082] In a preferred embodiment, the initiator is not an electron-poor monoisocyanate and is therefore preferably not selected from p-tolyl isocyanate, o-tolyl isocyanate and sulfonyl isocyanate, p-toluenesulfonyl methyl isocyanate, o-toluenesulfonyl methyl isocyanate, 4-chlorobenzylsulfonyl isocyanate, o-toluenesulfonyl isocyanate, p-toluenesulfonyl isocyanate and benzylsulfonyl isocyanate.

[0083] Preferred are polyepoxides according to the invention which can be prepared by polymerization of a monomer composition carried out in a solvent. It is particularly preferred to remove the solvent after the production of the polyepoxide, since in this way a particularly pure polyepoxide can be obtained. For other applications, it is also preferred that the solvent remains in the polyepoxide after the production of the polyepoxide, since the polyepoxide obtained in this way is particularly easy to handle and can be easily further processed into, for example, adhesives or coating materials.

[0084] The solvent is preferably selected from water, organic polar protic solvents, organic polar aprotic solvents and organic non-polar aprotic solvents and mixtures of these solvents, such as mixtures of different organic polar aprotic solvents with each other or mixtures of organic non-polar aprotic solvents with one or more organic polar protic solvents, wherein organic aprotic solvents are particularly preferred due to their chemical inertness. These include, for example, pentane, hexane, heptane, (iso) octane, methylcyclohexane, volatile oils and other alkanes, benzene, toluene, xylene and other aromatic hydrocarbons, methylene chloride, chloroform, ethylene dichloride 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 and carbon disulfide. Here, toluene, methylcyclohexane, n-butyl acetate, ethyl acetate and methyl ethyl ketone are very particularly preferred because they can dissolve the reactants used very well.

[0085] In principle, the solvent can be used with the monomer composition, the initiator and optionally the further reactants in any mixing ratio, wherein preferably it is added in a mass fraction of 5% or more (based on the mass of the resulting total formulation). In this case, a range of 5% to 40% is particularly preferred, since the amount of solvent used can be kept low. Furthermore, a range of 70% to 95% is particularly preferred, since solutions with a low epoxide fraction are obtained and the risk of yellowing is thus reduced. A range of 40% to 70% is very particularly preferred, since here a good compromise is achieved between the amount of solvent and the risk of yellowing.

[0086] Temperature is an important process parameter for controlling the molecular weight of the polyepoxide. For essentially all embodiments, the polyepoxide according to the invention is particularly preferred, wherein the polyepoxide can be prepared by polymerization of a monomer composition carried out at a temperature in the range of 50 to 150° C., preferably in the range of 60 to 130° C., wherein the polymerization of the monomer composition is particularly preferably carried out in the range of 50 to 90° C. or in the range between 90 and 120° C. The range of 50 to 90° C. is preferred here, because under these conditions the reaction proceeds relatively slowly and the reaction can be effectively controlled, while the range between 90 and 120° C. is preferred, because a balance between control and reaction speed is thus achieved.

[0087] The skilled person will appreciate that preferred polymer structures can be obtained from the above embodiments, wherein the polymer comprises monomer units obtained from the corresponding monomers, wherein the above embodiments regarding the base monomers also apply accordingly. Therefore, the present invention is closely related to polyepoxides for reactive adhesives, wherein the polyepoxides are copolymers having a plurality of monomer units of formula (II):

[0088]

[0089] Among them, based on the mass of polyepoxide, polyepoxide includes:

[0090] ib) one or more first monomer units in a combined mass fraction of 50% or more, wherein R represents a straight or branched alkyl group having 1 to 30 C atoms,

[0091] as well as

[0092] ii.b) one or more second monomer units in a combined mass fraction of 1% or more, wherein R represents a linear or branched organic group having 1 to 30 C atoms and including at least one reactive functional group, wherein R does not include an epoxy group, and / or

[0093] iii.b) one or more third monomer units in a combined mass fraction of 1% or more, wherein R represents a linear or branched organic group having 2 to 30 C atoms including at least one epoxy group.

[0094] In this regard, a method for producing a polyepoxide, preferably a polyepoxide according to the present invention, is disclosed, comprising the following method steps:

[0095] a) manufacturing or providing a monomer composition, based on the mass of the monomer composition, the monomer composition comprising:

[0096] i) one or more first monomers in a combined mass fraction of 50% or more, wherein the first monomer is selected from alicyclic monoepoxy-functional monomers of formula (I), wherein R represents a linear or branched alkyl group having 1 to 30 C atoms, and

[0097] ii) one or more second monomers in a combined mass fraction of 1% or more, wherein the second monomer is selected from alicyclic monoepoxy-functional monomers of formula (I), wherein R represents a linear or branched organic group having 1 to 30 C atoms including at least one reactive functional group, and / or

[0098] iii) one or more third monomers in a combined mass fraction of 1% or more, wherein the third monomer is selected from a polyepoxy-functional monomer of formula (I), wherein R represents a linear or branched organic group having 2 to 30 C atoms including at least one epoxy group, wherein formula (I) is:

[0099]

[0100] b) polymerizing the monomer composition to obtain the polyepoxide, preferably by cationic polymerization.

[0101] In a preferred embodiment of the corresponding method, the polymerization is terminated after a predetermined reaction time or when the desired conversion of the epoxy monomer is achieved by a further step. This can be achieved, for example, by cooling, diluting or adding a stopper. Therefore, in order to optimally adjust the desired low degree of branching and the desired molecular weight, the following corresponding method is preferred, wherein after the start of the polymerization, the polymerization is slowed down or terminated in method step (b) by one or more deceleration measures, wherein the deceleration measures are selected from cooling, diluting and adding a stopper, wherein the deceleration measures preferably include adding a stopper, wherein particularly preferably adding a stopper before cooling.

[0102] Terminator or terminator is a substance or mixture of substances that interacts with the reactive species of the polymerization reaction and prevents further chain growth by chemical reaction. This chemical interaction is usually based on the setting of chemical equilibrium, so that a certain time can be passed from the addition of terminator to the polymerization stop. Within the scope of the present invention, terminator is a substance or mixture that can ensure that no further epoxy monomer conversion is observed within 30 minutes at the latest after mixing. Particularly preferably, terminator comprises an organic or inorganic base and preferably a solvent, and the organic or inorganic base is, for example, sodium hydroxide, potassium hydroxide, ammonium hydroxide, potassium acetate, ammonium acetate, sodium acetate, pyridine, pyrrolidine, pyrroles, piperidine, indole, imidazoles, pyrazoles, imidazoline, (iso) quinoline, purine, pyrimidine, 4-vinylpyridine or 4-ethylpyridine, wherein pyridine and 4-ethylpyridine are very preferred. Also preferably add gas as terminator, because this can be distributed in the reaction mixture particularly quickly. At this, particularly preferably use ammonia.

[0103] In view of the above-mentioned embodiments, the corresponding process is preferred, wherein the polymerization in process step b) is carried out so that an epoxy group conversion of 10% or more, preferably 30% or more, is achieved, wherein the epoxy group conversion is preferably in the range of 20 to 35%. If no third monomer is used to obtain a second epoxy group, even the corresponding process is preferred, wherein the polymerization in process step b) is carried out so that an epoxy group conversion of 50% or more, very particularly preferably 70% or more, particularly preferably 90% or more, is achieved, wherein the epoxy group conversion is preferably in the range of 35 to 60% or in the range of 60 to 100%.

[0104] Furthermore, preferred embodiments with regard to the producibility of the polyepoxide according to the invention for a corresponding method emerge from the above-described embodiments.

[0105] Analogously, corresponding processes are preferred in practice, in which 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 epoxy groups in the monomer composition, and / or wherein the initiator is preferably supplied gradually or continuously.

[0106] Analogously, therefore, corresponding processes are also preferred, in which the polymerization of the monomer composition is initiated by a cationic thermal initiator or a cationic photoinitiator, particularly preferably by a latent, heat-activatable cationic initiator.

[0107] Analogously, corresponding processes are likewise preferred, in which the polymerization of the monomer composition is carried out in a solvent.

[0108] Furthermore, analogously, corresponding processes are therefore preferred, in which the polymerization of the monomer composition is carried out at a temperature in the range of 50 to 150° C., preferably 60 to 130° C., wherein the polymerization of the monomer composition is particularly preferably carried out at a temperature in the range of 50 to 90° C. or in the range between 90 and 120° C.

[0109] Furthermore, preference is given to corresponding processes which are carried out as a semi-batch or fed-batch process.

[0110] In particular, in the case of the reaction of the preferred monomer composition comprising the second monomer, a great advantage of the corresponding process is that, if desired, the polyepoxide produced can be further crosslinked in a controlled manner by reactive functional groups, the concentration of which in the copolymer can be controlled very accurately, even before use in the adhesive to improve the rheological properties. Preference is therefore given to corresponding processes which additionally comprise the following process steps:

[0111] c) partially crosslinking the polyepoxide to increase the weight average molecular weight M w wherein the crosslinking is effected at least partially, preferably predominantly, particularly preferably substantially completely, via monomer units derived from the second monomer and / or the third monomer, preferably via monomer units derived from the second monomer.

[0112] The invention also relates to a curable adhesive comprising the polyepoxide according to the invention.

[0113] Curable adhesive according to the present invention is curable. Due to the possibility of curing, curable adhesive can be used as structural adhesive after curing. According to DIN EN 923:2006-01, structural adhesive is an adhesive that forms the following adhesive connection, and the adhesive connection can keep the fixed strength (according to ASTM definition: "bonding agents used for transferring required loads between adherends exposed to service environments typical for the structure involved") in a given long time in the structure. Therefore, it is an adhesive for chemical and physical high stress bonding, which helps to strengthen the tape in the cured state. In other words, it is a reactive adhesive.

[0114] For the subsequent end use, the curable adhesive is particularly preferably a pressure-sensitive adhesive, wherein the adjustment of the cohesion required for the pressure-sensitive adhesive properties of the adhesive is advantageously facilitated by the use of the polyepoxides according to the invention.

[0115] According to the understanding of the technician, pressure-sensitive adhesive is understood to refer to an adhesive with pressure-sensitive adhesive properties, that is, the ability to form a permanent connection with the adhesion substrate even under relatively weak applied pressure. The corresponding pressure-sensitive tape can be separated (peeled off) again from the adhesion substrate substantially without residue after use, and generally, even at room temperature, there is permanent inherent viscosity, which means that they have a certain viscosity and touch viscosity (contact viscosity), so that they can wet the surface of the substrate even under low applied pressure. Do not wish to be bound by this theory, often assume that pressure-sensitive adhesive can be regarded as a fluid with extremely high viscosity of elastic components (components), which correspondingly has the characteristic viscoelastic properties that cause the above-mentioned permanent inherent viscosity and pressure-sensitive adhesive ability. Assume that in the case of the corresponding pressure-sensitive adhesive, when mechanically deformed, there is both a viscous flow process and the formation of elastic restoring force. Proportional (at a certain proportion) viscous flow is used to realize adhesion here, and for realizing cohesion, proportional (at a certain proportion) elastic restoring force is particularly required. The relationship between rheology and pressure-sensitive adhesive properties is known in the prior art and is described, for example, in Satas, "Handbook of Pressure Sensitive Adhesives Technology", 3rd edition (1999), pages 153 to 203. To characterize the measure of the elastic and viscous components, the storage modulus (G') and the loss modulus (G") which can be determined by means of dynamic mechanical analysis (DMA) (e.g., using a rheometer) are usually used, as disclosed, for example, in WO 2015 / 189323. Within the scope of the present invention, if at a temperature of 23°C, at 10 0 Up to 10 1 rad / sec (radian / sec), G′ and G″ are each at least partially located within the range of 10 3 Up to 10 7 Pa, the adhesive is preferably understood to be pressure-sensitive and therefore as a pressure-sensitive adhesive.

[0116] Initiators for the curable adhesive may in turn be the customary initiators known to the person skilled in the art, particular preference being given to using initiators of the type disclosed above in connection with the preparation of the preferred polyepoxides.

[0117] It can be seen that the advantage of the curable adhesive according to the invention is that, in addition to the presence of the polyepoxide according to the invention, the curable adhesive is very flexible in terms of the use of typical additives, so that the physicochemical properties can be further specifically adapted to the requirements of the respective application purpose. Therefore, the following 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 of 0.1 to 50%, preferably in the range of 0.2 to 40%, based on the mass of the adhesive, and / or wherein the one or more further additives are preferably selected from tackifying resins, anti-aging agents, light protection agents, UV absorbers, fillers and rheological additives.

[0118] The present invention also relates to an adhesive tape comprising a curable adhesive according to the invention. The skilled person will appreciate that the adhesive tape according to the invention is a reactive adhesive tape and, according to the above-described embodiment, preferably a pressure-sensitive adhesive tape. An adhesive tape according to the invention is preferred in which 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 in which the adhesive tape comprises a cover layer arranged on the adhesive.

[0119] Finally, the use of the adhesive tape according to the invention for bonding two or more components is disclosed. Preference is given to uses in which curing takes place at least partially by reaction of reactive functional groups of the polyepoxide according to the invention which are not epoxide groups.

[0120] Hereinafter, preferred embodiments of the present invention will be further explained and described with reference to experiments. DETAILED DESCRIPTION

[0121] A. Sample manufacturing:

[0122] Polyepoxides E1 to E6 were produced. For this purpose, a screw-top glass equipped with a magnetic stirring bar and a rubber septum was charged with the corresponding initiator (0.017-0.400 mol %, see Table 1) and dissolved in acetone to give a 5% solution.

[0123] The monomer composition (about 5.0 g) and the solvent (about 5.0 g) were added, the glass was sealed, and the reaction mixture was stirred at room temperature for 5 minutes. Then, polymerization was carried out at the temperature (80-110° C.) and 200 rpm shown in Table 1 for t=24 hours, after which it was terminated by adding pyridine (ten times the amount of the initiator) and cooled to room temperature.

[0124] The parameters used in the fabrication are listed in Table 1.

[0125] Table 1

[0126]

[0127]

[0128] *The concentration of initiator in mol% refers to the total amount of epoxy monomer

[0129] The materials used here are listed in Table 2.

[0130] Table 2

[0131]

[0132] B. Analysis

[0133] To determine the conversion of epoxy groups, samples (0.40 mL each time) were taken through the septum with a syringe not only before the start of the polymerization but also at specified intervals and mixed with a 6.25% solution of pyridine in ethanol (40 μL).

[0134] The molecular weight distribution of the obtained polymer solution was determined by GPC. The determination was carried out at a flow rate of 0.5 mL / min at 25°C using degassed THF as eluent, 100 μL injection volume and 1 g / L sample concentration on a system consisting of a PSS SECecurity 1260 HPLC pump, a PSS SDV 10 μm ID 8 mm x 50 mm precolumn, a PSS SDV 10 μm 10 3 ID 8mm x 300mm, PSSSDV 10μm 10 5 ID 8mm x 300mm, PSS-SDV 10μm 10 7 ID 8mm x300mm and SECcurity differential refractometer detector (RI). PSS-WinGPC UniChrome 8.33 version software is used to record and evaluate data. Polystyrene standards are used for calibration, and the polystyrene standards are usually converted to poly (methyl methacrylate) calibration by means of Mark Houwink coefficients K and α. By obtaining GPC results, the solubility standards of the polyepoxides according to the present invention are met at the same time. This shows that the polyepoxides present here are non-crosslinked. The technician is aware that in the sample preparation process, in order to obtain meaningful results, at least 95% by weight of the sample to be examined is dissolved in the corresponding eluent (THF in this case).

[0135] The conversion of the epoxy resin was determined by FTIR or NMR based on the observed species.

[0136] In order to quantify the time-dependent conversion of the epoxy monomer in the case of monomer 1, the shrinkage of the epoxy band in the infrared spectrum was used. For this purpose, the epoxy band (778 to 812 cm -1 ) and carbonyl bands (1650 to 1800 cm -1 ). The integral ratio before the start of polymerization is used as a reference for 0% conversion. Therefore, the epoxy monomer conversion rate U(t) that changes with time can be obtained by the following relationship:

[0137]

[0138] In the case of monomer 2, in order to quantify the conversion of the epoxy monomer over time, the growth of the polyether band in the IR spectrum was used. For this purpose, the polyether region (996 to 1115 cm -1 ) and carbonyl bands (1660 to 1770 cm -1 The time-varying epoxy monomer conversion U(t) is determined by means of a correlation equation created by calibration using the conversion determined using NMR spectroscopy:

[0139]

[0140] Fourier transform infrared spectroscopy (FTIR) was performed using a Platinum Diamant-ATR unit in the range of 4000 to 400 cm -1 The spectral range is within 2cm -1 The samples were recorded on a Bruker Vertex 70 at a resolution of 1.5 Å. The evaluation was performed using OPUS software. 1 H NMR spectra were recorded on a Bruker AVIII (300 MHz) or Bruker AVII+ (500 MHz) with a 10 mm BBO / 5 mm BBFO sample head. Evaluation was performed using TopSpin software.

[0141] The obtained results are summarized in Table 3.

[0142] Table 3

[0143]

[0144]

[0145] The GPC results show that non-crosslinked polyoxides according to the invention can be obtained with advantageous molecular weights, wherein in particular non-crosslinked polyepoxides according to the invention with high molecular weights can also be obtained (see Examples E4-E6). These are particularly well suited for the formulation of reactive pressure-sensitive adhesives. For this purpose, the dissolved polyepoxides of Examples E4 to E6 were formulated with 1,6-hexanediol diacrylate (HDDA) in each case in a ratio of 90% by weight to 10% by weight (based on the solids content), applied and dried according to methods known to those skilled in the art. The films produced all showed advantageous pressure-sensitive adhesive properties.

[0146] The person skilled in the art recognizes the advantageous properties of the polyepoxides according to the invention from the fact that they can be easily controlled via the number (fraction of monomer 2 and / or monomer 3, initiator concentration) and type (selection of monomer 2 and / or monomer 3) of crosslinking points along the polyepoxide polymer chain. The person skilled in the art recognizes in particular that the polyepoxides according to the invention can be advantageously used to construct reactive pressure-sensitive adhesives, since the polyepoxides according to the invention can first be used to formulate pressure-sensitive adhesives, which can then be processed to give pressure-sensitive adhesive tapes, which can be cured in a further step after the pressure-sensitive adhesive tapes have been applied.

[0147] In contrast, epoxy adhesives according to the prior art are usually applied as a fluid formulation and cured in one step. Alternatives to epoxy-based pressure-sensitive adhesive tapes based on epoxy-functionalized novolacs or monomeric epoxy compounds or on the basis of initial polymerization of epoxy resins There are the above-mentioned disadvantages which are easily recognized by those skilled in the art.

Claims

1. A polyepoxide for use in a reactive adhesive, 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 monomer is selected from alicyclic monoepoxy-functional monomers of 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 monomer is selected from alicyclic monoepoxy-functional monomers of formula (I), wherein R represents a linear or branched organic group having 1 to 30 C atoms including 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 monomer is selected from a polyepoxy-functional monomer of formula (I), wherein R represents a linear or branched organic group having 2 to 30 C atoms including at least one epoxy group, wherein formula (I) is:

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

3. The polyepoxide according to claim 1, wherein the monomer composition comprises a third monomer. 4 . The polyepoxide according to claim 1 , wherein the polyepoxide has a mass-related gel fraction in toluene of 10% or less.

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

6. The polyepoxide according to claim 1, wherein the polyepoxide is preparable by polymerization of a monomer composition initiated by a cationic initiator.

7. The polyepoxide according to claim 1, wherein the polyepoxide is preparable by polymerization of a monomer composition carried out in a solvent.

8. The polyepoxide according to claim 1, wherein the polyepoxide is preparable by polymerization of the monomer composition carried out at a temperature in the range of 50 to 150°C.

9. A curable adhesive comprising a polyepoxide according to any one of claims 1 to 8.

10. An adhesive tape comprising the curable adhesive according to claim 9.

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