DE102022117183A1 - Uncrosslinked polyepoxide and adhesive composition comprising this polyepoxide - Google Patents

Abstract

The invention relates to a polyepoxide for use in reactive adhesives, wherein the polyepoxide can be produced 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, 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 alkyl group with 1 to 30 carbon 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), where R represents a linear or branched organic radical with 1 to 30 carbon 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, the third monomers being selected from the group consisting of multiepoxy-functional monomers of the formula (I), where R represents a linear or branched organic radical with 2 to 30 C atoms, which comprises at least one epoxy group, the formula (I): corresponding.

Description

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 method for producing a corresponding polyepoxide and the use of a corresponding adhesive tape for bonding two or more components.

Joining separate elements is one of the central processes in manufacturing technology. In addition to other methods, such as welding and soldering, bonding, i.e. joining using an adhesive, is particularly important today. An alternative to using shapeless adhesives, which are applied from a tube, for example, are so-called adhesive tapes.

From everyday life, pressure-sensitive adhesive tapes in particular are known in which a pressure-sensitive adhesive ensures the adhesive effect, which is permanently sticky and adhesive under normal environmental conditions. Corresponding pressure-sensitive adhesive tapes can be applied to a substrate by pressure and remain stuck there, but can later be removed more or less without leaving any residue.

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

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

Despite the mostly advantageous reactivity of the epoxy compounds known from the prior art in curing reactions, they are perceived as disadvantageous for some areas of application because of their physicochemical properties. In particular, many of the commercially relevant epoxy compounds are liquid, which in many cases functionally limits their usability in adhesives, since the cohesion of the adhesive should not be reduced too much. This is particularly relevant if a certain degree of adhesive tack is to be achieved for a reactive adhesive tape before curing for the purpose of the best possible processability by the end user, so that reactive adhesive tapes can, if necessary, be removed essentially without leaving any residue before curing, for example if there are too due to incorrect application of an adhesive tape.

In light of the above statements, there is an interest in the area of adhesive technology in obtaining epoxy compounds which have the crosslinkability necessary for curing, but which also have sufficient solubility and advantageous rheological properties, in particular increased viscosity, and which accordingly can 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 to a large extent from that which could be achieved by polymerizing epoxides , can be considered disadvantageous for some applications.

An alternative approach to this is based on the so-called partial polymerization of monomeric epoxy compounds, ie a limited polymerization or oligomerization, which increases the molecular weight of the resulting compounds, but does not result in such a crosslinking of the monomeric epoxy compounds that they are chemically complete or network too strongly. One correspond the procedure is for example in the EP 3101047 A1 disclosed. However, the processes known from the prior art are perceived as disadvantageous in many cases because the desired polymerization is often not easy to control. This is due in particular to the fact that the epoxy compounds for use in the later reactive adhesive should usually have the ability to crosslink with one another and accordingly contain two or more epoxy groups. As a result, unwanted crosslinking can easily occur during polymerization, for example due to local inhomogeneities in the initiator concentration, which results, for example, in the formation of insoluble precipitates. In addition, this procedure reduces the concentration of reactive epoxide groups, so that the reactivity and in particular the possibility of controlled adjustment of the reactivity is perceived as inadequate in many cases.

Further information on the technological background in the area 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.

The primary object of the present invention was to eliminate or at least reduce the disadvantages of the prior art described above.

In particular, it was the object of the present invention to provide uncrosslinked epoxy compounds with advantageous rheological properties which can be used in high-performance reactive adhesives with advantageous cohesion.

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.

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

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

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.

The inventors of the present invention have now found that the tasks described above can surprisingly be achieved by polyepoxides, which are produced by co-polymerization of a specific class of cycloaliphatic monoepoxy-functional monomers with specific cycloaliphatic monoepoxy-functional monomers which comprise reactive functional groups which are not are epoxy groups, and/or with specific cycloaliphatic multiepoxy-functional monomers, as defined in the claims.

This specific combination makes it surprisingly possible to obtain particularly efficiently uncrosslinked epoxy compounds with advantageous and easily adjustable rheological properties, which enable the setting of an advantageous cohesion in curable adhesives, the polyepoxides being easy to process because of their sufficient solubility in common solvents , especially when mixed with other components of the curable adhesive, and in the end use allow reliable curing of the curable adhesive.

The reactivity of the polyepoxides in the later 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 include reactive functional groups that are not epoxy groups, allows the particularly controlled introduction of reactive groups into the polyepoxides, which are available for later chemical crosslinking, without this When the epoxy monomers are polymerized, this can lead to undesirable crosslinking, which in particular also makes high concentrations of reactive groups in the polyepoxide accessible, which, depending on the design, are precisely activated via the curable adhesive mass selected curing mechanism can be controlled, for example in the course of further crosslinking of the adhesive in the adhesive tape and / or during later curing in the end application. Advantageously, however, a chemical bond to the substrate can also be made possible via the reactive groups in the later adhesive application.

The above-mentioned objects are thus achieved by the subject matter of the invention, as defined in the claims. Preferred embodiments according to the invention result from the subclaims and the following statements.

Such embodiments, which are referred to below as preferred, are combined in particularly preferred embodiments with features of other embodiments designated as preferred. Combinations of two or more of the embodiments described below as particularly preferred are therefore very particularly preferred. Also preferred are embodiments in which a feature of one embodiment that is designated as preferred to some extent is combined with one or more further features of other embodiments that are designated as preferred to some extent. Features of preferred curable adhesives, adhesive tapes, processes and uses result from the features of preferred polyepoxide.

Insofar as both specific amounts or proportions of this element and preferred embodiments of the element are disclosed below for an element, for example for the monoepoxy-functional or multiepoxy-functional monomers, in particular the specific amounts or proportions of the preferably designed elements are also disclosed. In addition, it is disclosed that in the corresponding specific total quantities or total proportions of the elements, at least some of the elements can be preferably designed and in particular also that preferably designed elements within the specific total quantities or total proportions can in turn be present in the specific quantities or proportions.

• i) ein oder mehrere erste Monomere in einem kombinierten Massenanteil von 50 % oder mehr, wobei die ersten Monomere ausgewählt sind aus der Gruppe bestehend aus cycloaliphatischen monoepoxyfunktionellen Monomeren der Formel (I), wobei R für eine lineare oder verzweigte Alkylgruppe mit 1 bis 30 C-Atomen steht, sowie
• ii) ein oder mehrere zweite Monomere in einem kombinierten Massenanteil von 1 % oder mehr, wobei die zweiten Monomere ausgewählt sind aus der Gruppe bestehend aus cycloaliphatischen monoepoxyfunktionellen Monomeren der Formel (I), wobei R für einen linearen oder verzweigten organischen Rest mit 1 bis 30 C-Atomen steht, der zumindest eine reaktive funktionelle Gruppe umfasst, und/oder
• iii) ein oder mehrere dritte Monomere in einem kombinierten Massenanteil von 1 % oder mehr, wobei die dritten Monomere ausgewählt sind aus der Gruppe bestehend aus multiepoxyfunktionellen Monomeren der Formel (I), wobei R für einen linearen oder verzweigten organischen Rest mit 2 bis 30 C-Atomen steht, der zumindest eine Epoxy-Gruppe umfasst, wobei die Formel (I):
  
  entspricht.

The invention relates to a polyepoxide for use in reactive adhesives, wherein the polyepoxide can be produced 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, the first monomers being selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), where R represents a linear or branched alkyl group with 1 to 30 C -atoms stands, as well
• ii) one or more second monomers in a combined mass fraction of 1% or more, the second monomers being selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), where R represents a linear or branched organic radical with 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, the third monomers being selected from the group consisting of multiepoxy-functional monomers of the formula (I), where R represents a linear or branched organic radical with 2 to 30 C atoms which comprises at least one epoxy group, the formula (I):
  
  corresponds.

The polyepoxides according to the invention are copolymers which are or can be produced by polymerization from a specific monomer composition. In accordance with expert understanding and the usual approach in the field of technology, it is expedient to use such copolymers via the manufacturing process or the manufacturing process The starting materials used must be defined, since it is largely impossible to define the corresponding materials in their entirety in any other way.

In accordance with the usual procedure in the field of technology, the producibility is stated in relation to the monomer composition, which, in accordance with the expert understanding, includes all monomeric components which are converted into monomer units of the polyepoxide in the course of the 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.

The components of the monomer composition defined above are each used as “one or more” in accordance with the understanding of those skilled in the art. The expression “one or more” refers, in the usual manner in the industry, to the chemical nature of the corresponding monomers and not to their amount of substance. For example, the monomer composition may exclusively comprise methyl 3,4-epoxycyclohexylcarboxylate as the first monomer, which would mean that the monomer composition comprises a large number of the corresponding molecules.

In the usual way, the mass proportions of the components in the monomer composition are given as combined mass proportions of the one or more monomers, which expresses that the mass proportion of the correspondingly formed monomers taken together meets the corresponding criteria, with the mass of the monomer composition forming the reference system.

The person skilled in the art adapts 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 in all cases include 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 well known to those skilled in the art 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 that is not an epoxy group, the production can also include further polymerization steps using other polymerization processes. In practice, however, these alternative polymerization processes will generally only make a small contribution in view of the high epoxide concentrations, so that polyepoxides according to the invention are preferred, which can essentially only be produced using cationic polymerization.

The above statement that the polyepoxides are suitable for use in reactive adhesives, i.e. as a reactive component of the reactive adhesives, implies to the person skilled in the art that they are uncrosslinked polyepoxides, which can be further crosslinked in a reactive adhesive and physically have chemical properties that enable them to be used in reactive adhesives, especially with regard to solubility in common solvents. Crosslinked polyepoxides, in which the polymerization has led to the formation of a network and which therefore represent essentially insoluble, mostly thermoset materials in most solvents, do not meet this suitability.

In accordance with the expert understanding, the term “uncrosslinked” refers to 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 through entanglement, phase separation or crystallization .

The person skilled in the art will understand that an uncrosslinked polyepoxide does not necessarily have to be linear, but can also have copolymer chains with branches, which can be the case in particular when the monomer composition comprises third monomers. Even if the transition from branched co-polymer chains to the network of a cross-linked polyepoxide may seem unclear in theory, the uncross-linked state or suitability for use in reactive adhesives can be determined relatively easily in practice by the person skilled in the art, whereby the A person skilled in the art can determine this, for example, based on the rheological properties or their temperature dependence or with a simple solubility test.

Based on the typical practice-relevant evaluation criteria for determining the sufficiently uncrosslinked state, the inventors believe that properties of the polyepoxides according to the invention can be specified in which the suitability for use in reactive adhesives or the “uncrosslinked” property is present in any case, based on the crosslinking state. These are given below and relate to the properties of solubility or gel content as well as the weight-average molecular weights. Conversely, in these cases it is also preferred to produce the polyepoxides according to the invention in this form because of their good suitability for use in reactive adhesives.

In this respect, preference is initially given to a polyepoxide according to the invention, the polyepoxide being soluble at 23 ° C in one or more solvents selected from the group consisting of acetone, methyl ethyl ketone, gasoline, toluene, ethanol, isopropanol, ethyl acetate and diethyl ether. In this respect, a polyepoxide according to the invention is also preferred, the polyepoxide having 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 proportion 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 fleece bag made of polyethylene (Tyvek fleece). The weight fraction of the polymer that is not soluble in the solvent is determined from the difference in the sample weights before the extraction and after a 72-hour extraction through the solvent, i.e. through toluene, acetone or methyl ethyl ketone, preferably through toluene, at 23 °C. The extractant is renewed after 24 hours and after 48 hours. The sample mass remaining in the bag results in the gel content based on the mass of the polymer, which is also referred to as the gel value. The value is given as the mean value of a triplicate determination in %.

With regard to the sufficiently uncrosslinked state, a polyepoxide according to the invention is also preferred, the co-polymer chains in the polyepoxide having a maximum molecular weight (GPC) of 10 ⁷ g/mol or less, preferably of 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, very 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 300,000 g/mol, preferably in the range from 2000 to 200,000 g/mol, particularly preferably in the range from 3000 to 100,000 g/mol, with ranges from 1000 to 10,000 g/mol or alternatively from 10,000 to 100,000 g/mol being particularly preferred.

The information about the weight-average molecular weight M _w refers to the determination using gel permeation chromatography (GPC). The determination is carried out with degassed THF as mobile phase, 100 µL 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 and a PSS SDV 10 µm ID 8 mm × 50 mm guard column, a PSS SDV 10 µm 10 ³ Å ID 8 mm × 300 mm, a PSS SDV 10 µm 10 ⁵ Å ID 8 mm × 300 mm, a PSS SDV 10 µm 10 ⁷ Å ID 8 mm × 300 mm and a SECcurity differential refractometer detector (RI). The data is recorded and evaluated using the software PSS - WinGPC UniChrome Version 8.33. The calibration is carried out using polystyrene standards, which are universally converted into a poly(methyl methacrylate) calibration using the Mark Houwink coefficients K and α.

A polyepoxide according to the invention is preferred, the polyepoxide being a thermoplastic solid at 25 ° C and 100 kPa pressure.

unterscheiden sich jedoch hinsichtlich des jeweiligen Restes R.According to the above definition, various monomeric epoxy compounds are used in the monomer composition. According to the understanding of those skilled in the art, epoxy compounds are those compounds which carry at least one oxirane group. The monomers to be used as the first, second and third monomers are each cycloaliphatic, which means that their structure includes at least one ring system, but no aromatic ring system. The monomers to be used as 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.

The first monomers have no reactive functional groups in the radical R, i.e. neither epoxy groups nor other reactive functional groups. Rather, in the case of the first monomers, the radical R is an alkyl group, which can be linear or branched in the usual way, with linear radicals being more preferred. According to the inventors' assessment, it is in particular the large mass fraction of these monoepoxy-functional monomers, which do not have any reactive functional groups in the radical R, which enables the advantageous properties of the polyepoxides according to the invention and through which the result is uncrosslinked and particularly suitable for use in reactive adhesives Polyepoxides are made possible.

In this respect, the inventors have succeeded in specifying particularly preferred embodiments for the first monomers, with which, 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 with 1 to 30 C atoms, according to the inventors' assessment, particularly advantageous polyepoxides according to the invention can be obtained. Preferred is a polyepoxide according to the invention, the first monomers being selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), where R is a linear or branched, preferably linear, alkyl group with 1 to 20 carbon atoms, preferably with 1 to 10 carbon atoms, particularly preferably with 1 to 5 carbon atoms, where R particularly preferably represents a methyl, ethyl or propyl group. Particularly preferred is a polyepoxide according to the invention, where the first monomer is 3,4-epoxycyclohexylcarboxylic acid methyl ester, and/or where 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.

The second monomers are also monoepoxy-functional monomers, but, in contrast to the first monomers, have at least one reactive functional group in the radical R. The expression “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) is already an epoxy group having. The inventors have also succeeded in specifying particularly preferred embodiments for the second monomers, which, in the inventors' opinion, are based on the cycloaliphatic monoepoxy-functional monomers of the formula (I), in which R represents a linear or branched, preferably linear, organic radical 1 to 30 carbon atoms, which comprises at least one reactive functional group, can be used to obtain particularly advantageous polyepoxides according to the invention and which are particularly suitable for targeted subsequent crosslinking via the corresponding functional groups.

In this respect, preference is initially given to a polyepoxide according to the invention, the second monomers being selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), where R is a linear or branched, preferably branched, organic radical with 2 to 20 carbon atoms with 3 to 10 carbon atoms, which includes at least one reactive functional group. Additionally or alternatively, a polyepoxide according to the invention is preferred, the reactive functional group being selected from the group consisting of alkoxysilane groups, hydroxy groups, amine groups, isocyanate groups, carboxylic acid groups, carboxylic anhydrides and C = C double bonds is selected from the group consisting of alkoxysilane groups, hydroxy groups, carboxylic acid groups, carboxylic anhydrides and C = C double bonds, particularly preferably selected from the group consisting of hydroxy groups and C = C double bonds, and / or where 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, where the second monomer is ((3,4-epoxycyclohexyl)methyl) methacrylate, and/or where 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 monomers.

In view of a pronounced crosslinkability, in the opinion of the inventors, it is possible to design the second monomers with several reactive functional groups, which can be the same or different, depending on whether a different reactivity in the side chains is desired or not. A polyepoxide according to the invention is therefore preferred, wherein the second monomers comprise two or more reactive functional groups, in particular similar reactive functional groups.

In addition or as an alternative 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.

In the inventors' opinion, preference is given to starting from the multiepoxy-functional monomers of the formula (I), in which R represents a linear or branched, preferably linear, organic radical with 2 to 30 carbon atoms, which comprises at least one epoxy group Polyepoxide according to the invention, the third monomers being selected from the group consisting of multiepoxy-functional monomers of the formula (I), where R is a linear or branched, preferably branched, substituted organic radical with 3 to 25 C atoms, preferably with 4 to 20 C atoms, particularly preferably with 6 to 15 carbon atoms, which comprises at least one epoxy group.

Preference is given to a polyepoxide according to the invention, where the epoxy group is an epoxy group or an oxetane group, preferably an epoxy group, and/or where the third monomers are selected from the group consisting of bis-epoxy-functional monomers.

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

Particularly preferred is a polyepoxide according to the invention, where the third monomer is a bis-epoxycyclohexyl derivative, preferably ((3,4-epoxycyclohexyl)methyl-3,4-epoxycyclohexylcarboxylate, and/or where the monomer composition is 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 third monomers.

In the context of the present invention, the term “monomers” is to be understood broadly and primarily serves to clearly differentiate the starting compounds from the copolymer of the polyepoxide. The term expresses that the monomers should be incorporated into the copolymer. The person skilled in the art understands that the term “monomers” also includes low molecular weight compounds that could be viewed as oligomers of one or more of the monomers. In accordance with the expert understanding, this is expedient because oligomerization can occur unnoticed and the resulting oligomers in the sense of the above definition can be produced from the corresponding monomers anyway, so that the presence of oligomers, so to speak as an intermediate stage, has no influence the producibility of the polyepoxides according to the invention from the monomer composition would have. 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 molar mass in the range from 75 to 1000 g/mol, preferably in the range from 100 to 500 g/mol. 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, the third monomers having a molecular weight in the range from 75 to 1000 g/mol, preferably in the range from 150 to 500 g/mol, with the molecular weight particularly preferably in the range from 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.

As explained above, in the inventors' opinion, 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. Building 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 depending on requirements reactive side chains with epoxy groups or other reactive functional groups can be increased.

Because of the different crosslinking chemistry this opens up, it is explicitly preferred for essentially all embodiments if the monomer composition comprises at least small amounts of second monomers, and in particular the combination of second and third monomers is 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, through which the rheological properties of the polyepoxides according to the invention can be optimized.

In this respect, the inventors have succeeded in specifying mass ratios and mass proportions of the various monomers with which, in the inventors' opinion, particularly high-performance polyepoxides according to the invention can be obtained.

First of all, preferred ranges could be identified for the mass proportions of the respective monomers. Preferred is a polyepoxide according to the invention, the combined mass fraction of the first monomers being 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. Also preferred is a polyepoxide according to the invention, the combined mass fraction of the first monomers being 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 adapting to the requirements of various applications, preference is given to a polyepoxide according to the invention, the combined mass fraction of the first monomers being 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.

With regard to the second monomers, preference is given to a polyepoxide according to the invention, the combined mass fraction of the second monomers being 2% or more, preferably 5% or more, particularly preferably 10% or more, based on the mass of the monomer composition. In this respect, a polyepoxide according to the invention is also preferred, the combined mass fraction of the second monomers being 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 . In turn, preferred for adapting to the requirements of various applications is a polyepoxide according to the invention, the combined mass fraction of the third monomers being 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.

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, particularly 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. Particularly preferred is, additionally or alternatively, a polyepoxide according to the invention, the combined mass fraction of the second monomers and the third monomers being 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 monomers and the third monomers is in the range from 2 to 40%, preferably in the range from 4 to 30%, particularly preferably in the range from 10 to 20%, based on the mass of the monomer composition. Additionally or alternatively, a polyepoxide according to the invention is preferred for various application scenarios, the combined mass fraction of the second monomers and the third monomers being in the range of 1 to 5% or in the range of 5 to 20% or in the range of 20 to 40%, since With these areas in the networking, networks of different densities can be obtained, with which the application properties can be tailored particularly well to the desired requirements, especially with regard to the pressure-sensitive tack and performance as a structural adhesive.

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, particularly 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. Particularly preferred is, additionally or alternatively, a polyepoxide according to the invention, the combined mass fraction of the second monomers and the third monomers being 2% or more, preferably 4% or more, particularly preferably 10% or more, based on the mass of the monomer composition, and /or where the combination ned 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%, particularly preferably in the range from 10 to 20%, based on the mass of the monomer composition.

The person skilled in the art understands 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 where the monomer composition does not comprise any third monomers or any second monomers.

Against this background, preference is given to a polyepoxide according to the invention, the monomer composition comprising 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, most 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, particularly preferably 100% is, based on the mass of the monomer composition.

Against this background, alternatively, a polyepoxide according to the invention is preferred, the monomer composition comprising 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, most 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% is, based on the mass of the monomer composition.

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, the inventors believe it is explicitly preferred to make the polyepoxides according to the invention as largely as possible from the corresponding ones to form specific epoxy compounds. A polyepoxide according to the invention is therefore preferred, the combined mass fraction of the first monomers, the second monomers and the third monomers being 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 Monomer composition

As explained above, it is possible for the monomer composition to also include other 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.

With regard to the other monomers, the use of diepoxy-functional monomers, which are not third monomers, is initially preferred. In this respect, preference is given to a polyepoxide according to the invention, the monomer composition comprising at least one diepoxy-functional monomer, which is 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.

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

In addition, for certain applications it is also advantageous to add vinyl ethers to the monomer composition, which can also be polymerized via cationic polymerization. Preference is therefore given to a polyepoxide according to the invention, 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, the combined mass fraction of all vinyl ether monomers which are not are second monomers or third monomers, 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 molecular weight in the range from 60 to 1000 g/mol, preferably in the range from 80 to 500 g/mol, with the molecular weight particularly preferably in the range from 80 to 200 g/mol or in Range from 200 to 350 g/mol or in the range from 350 to 500 g/mol.

The inventors have succeeded in identifying particularly favorable production conditions for the production of the polymers, with which reliably advantageous, uncrosslinked polyepoxides can be obtained. In this respect, because of the high relevance of the cationic polymerization, a polyepoxide according to the invention is explicitly preferred, whereby the polyepoxide can be produced by polymerizing the monomer composition, which is initiated by a cationic initiator, the cationic initiator preferably being used in a molar fraction in the range from 0.005 to 1% is based on the number of epoxy groups in the monomer composition. Additionally or alternatively, a polyepoxide according to the invention is preferred, with the cationic initiator preferably being supplied gradually or continuously.

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 appropriate, the solvent contained therein. 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.

Cationic initiators are fundamentally familiar to those skilled in the art from the prior art. The polyepoxides according to the invention can be produced 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 generator”) being particularly preferred. Accordingly, preference is given to a polyepoxide according to the invention, wherein the polyepoxide can be produced by polymerizing the monomer composition, which is initiated by a cationic thermal initiator or cationic photoinitiator, particularly preferably by a latently thermally activatable cationic initiator.

Suitable TAGs are known to those skilled in the art and are commercially available from numerous providers. Preferred are TAG that comprise a cation selected from the group consisting of 4-substituted benzylanilinium, 4-substituted benzylpyridinium, 4-substituted benzylphosphonium, S-substituted diphenylsulfonium and substituted aryl-benzylsulfonium, preferably 4-substituted benzylanilinium.

The TAG can in principle contain any anion, with weakly coordinating anions such as tetrafluoroborate (BF ₄ ^- ), hexafluorophosphate (PF ₆ ^- ), hexafluoroantimonate (SbF ₆ ^- ), tetrakis(pentafluorophenyl)borate (B(C ₆ F ₅ ) ₄ ^- ) and trifluoromethylsulfonate (F ₃ CSO ₃ ^- ) are preferred. Trifluoromethylsulfonate (F ₃ CSO ₃ ^- ) and hexafluorantimonate (SbF ₆ ^- ) are particularly preferred.

Combinations of a TAG made of cation and anion in which the resulting initiator has an activation temperature in the range from 50 ° C to 150 ° C are advantageous, with the person skilled in the art preferably adjusting the activation energy to the respective application requirements, in particular a Range from 80 ° C to 120 ° C is preferred in many cases in order to be able to carry out the polymerization at a comparatively moderate activation temperature and still enable a clearly defined initiation. The activation temperature of reactive or chemically activated adhesives in general or of the TAG used is determined calorimetrically using Differential Scanning Calorimetry (DSC). DIN EN ISO 11357-3:2013-04 certainly. To do this, approximately 20 mg of the sample is weighed into an aluminum crucible and placed in the measuring device (device: DSC 204 F1, Netzsch). Two heating curves are then recorded with a heating rate of 10 K/min. The samples are measured in Al crucibles with a perforated lid and a nitrogen atmosphere. A chemical reaction such as the activation of TAG can be seen as an exothermic peak in the thermogram. The onset temperature is noted as the activation temperature. This is determined for a peak as the intersection of the virtual interpolated baseline and the tangent created at the inflection point of the peak start (according to DIN EN ISO 11357-1:2010-03). By integrating the hardening peak, the reaction enthalpy is obtained in J/g.

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. For examples of sulfonium-based cations see the information in US 6,908,722 B1 referred. As examples of anions that serve as counterions for the cations mentioned above, are tetrafluoroborate, tetraphenyl bora, hexafluorophosphate, perchlorate, tetrachloroferrat, hexafluoroarenate, hexafluoroantimonate, pentafluorohydroxyantimonate, hexchloro anthlete Orophhenylborate, tetrakis (pentafluoromethyl-phenyl) borate, bi- (trifluoromethylsulfonyl )-amides and tris-(trifluoromethylsulfonyl)-methides. In addition, chloride, bromide or iodide are also conceivable as anions, particularly for iodonium-based initiators, 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, 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 4,058,401A , US 4,138,255 A and US 2010/063221 A1 disclosed.

Specific examples of sulfonium salts that can be used are triphenylsulfonium hexafluoroarsenate, triphenylsulfonium hexafluoroborate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis (pentafluorobenzyl) borate, methyldiphenylsulfonium tetrafluoroborate, methyldiphenyl sulfonium tetrakis (pentafluorobenzyl) borate, dimethyl phenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, diphenylnaphthylsulfonium hexafluoroarsenate, tritolylsulfonium hexafluorophosphate, anisyldiphenylsulfonium hexafluoroantimonate, 4- Butoxyphenyldiphenylsulfonium tetrafluoroborate, 4-chlorophenyldiphenylsulfonium hexafluoroantimonate, tris-(4-phenoxyphenyl)-sulfonium hexafluoro-phosphate, di-(4-ethoxyphenyl)-methylsulfonium hexafluoroarsenate, 4-acetylphenyldiphenylsulfonium tetrafluoroborate, 4-acetylphenyldiphenylsulfonium tetrakis -(pentafluorobenzyl)-borate, tris-(4-thiomethoxyphenyl )-sulfonium hexa-fluorophosphate, di-(methoxysulfonylphenyl)-methylsulfonium hexafluoro-antimonate, di-(methoxynaphthyl)-methylsulfonium tetrafluoroborate, di-(methoxynaphthyl)-methylsulfoniumetrakis-(penta-fluorobenzyl)-borate, di-(carbomethoxyphenyl)-methylsulfonium hexafluorophosphate, (4 -Octyloxyphenyl)-diphenyl-sulfonium tetrakis-(3,5-bis-trifluoromethylphenyl)-borate, Tris-[4-(4-acetylphenyl)-thiophenyl]-sulfonium tetrakis-(pentafluorophenyl)-borate, Tris-(dodecyl-phenyl)- sulfonium tetrakis (3,5-bis-trifluoromethylphenyl) borate, 4-acetamidophenyldiphenylsulfonium tetrafluoroborate, 4-acetamidophenyldiphenylsulfonium tetrakis (penta-fluoro-benzyl) borate, dimethylnaphthylsulfonium hexafluorophosphate, trifluoromethyldiphenyl sulfonium tetrafluoroborate, trifluoromethyldiphenyl sulfone ium tetrakis (pentafluorobenzyl) borate, phenylmethylbenzylsulfonium hexafluorophosphate, 5-methylthianthrenium hexa-fluorophosphate, 10-phenyl-9,9-dimethyl-thioxanthenium hexafluorophosphate, 10-phenyl-9-oxothioxanthenium tetrafluoro-borate, 10-phenyl-9-oxothioxanthenium tetrakis-(pentafluoro-benzyl)-borate, 5-methyl-10- oxothianthrenium tetrafluoroborate, 5-methyl-10-oxothianthreni-umtetrakis-(pentafluorobenzyl)-borate and 5-methyl-10,10-dioxothianthrenium hexafluorophosphates.

Specific examples of iodonium salts that can be used 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-thienyl-iodonium 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)-iodonium hexa-fluorophosphate, di-(2-benzothienyl)-iodonium hexafluorophosphate, diaryliodonium tristrifluoromethylsulfonylme thid such as diphenyliodonium hexafluoroantimonate, diaryliodonium tetrakis-(pentafluorophenyl) borate such as diphenyl-iodonium tetrakis-(pentafluorophenyl) borate, [4-(2-hydroxy-n-tetradesiloxy)-phenyl]-phenyliodonium hexafluoroantimonate, [4-(2-hydroxy-n- tetradesiloxy)-phenyl]-phenyliodonium trifluorosulfonate, [4-(2-hydroxy-n-tetradesiloxy)-phenyl]-phenyliodonium hexafluorophosphate, [4-(2-hydroxy-n-tetradesiloxy)-phenyl]-phenyliodonium tetrakis-(pentafluorophenyl)-borate, Bis-(4-tert-butylphenyl)-iodonium hexafluoroantimonate, bis-(4-tert-butylphenyl)-iodonium hexafluoro-phosphate, bis-(4-tert-butylphenyl)-iodonium trifluorosulfonate, bis-(4-tert-butylphenyl)-iodonium tetrafluoroborate, Bis-(dodecylphenyl)-iodonium hexafluoro-antimonate, bis-(dodecylphenyl)-iodonium tetrafluoroborate, bis-(dodecylphenyl)-iodonium hexafluorophosphate, bis-(dodecylphenyl)-iodonium trifluoro-methylsulfonate, di-(dodecylphenyl)-iodonium hexafluoroantimonate, di-(dodecylphenyl)- iodonium triflate, diphenyliodonium bisulfate, 4,4'-dichlorodiphenyliodonium bisulfate, 4,4'-dibromodiphenyliodonium bisulfate, 3,3'-dinitrodiphenyliodonium bisulfate, 4,4'-dimethyldiphenyliodonium bisulfate, 4,4'-bis-succinimidodiphenyliodonium bisulfate, 3-nitrodiphenyliodonium bisulfate, 4,4'- Dimethoxydiphenyliodonium bisulfate, bis-(dodecylphenyl)-iodonium tetrakis-(pentafluoro-phenyl)-borate, (4-octyloxyphenyl)-phenyliodonium tetrakis-(3,5-bis-trifluoromethyl-phenyl)-borate and (tolylcumyl)-iodonium tetrakis-(pentafluorophenyl)- borate, and ferrocenium salts (see for example EP 0 542 716 B1 ) such as η5-(2,4-cyclopentadien-1-yl)-[(1,2,3,4,5,6,9)-(1-methylethyl)-benzene]-iron.

Photoinitiators are typically used individually or as a combination 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 the literature known to those skilled in the art, such as “Industrial Photoinitiators: A technical guide” 2010 by A.W. Green, is referred.

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

In a preferred embodiment, the initiator is not an electron-poor monoisocyanate, and accordingly 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-toluenesulfony isocyanate and benzylsulfonyl isocyanate.

Preference is given to a polyepoxide according to the invention, where the polyepoxide can be produced by polymerizing the monomer composition, which is carried out in a solvent. It is particularly preferred if the solvent is removed after the polyepoxide has been produced, since particularly pure polyepoxides are accessible in this way. In addition, for other applications it is preferred if the solvent remains in the polyepoxide after the polyepoxide has been produced, since the polyepoxides obtained in this way are particularly easy to handle and can easily be further processed, for example in adhesives or coating materials.

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, 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 very particularly preferred, since they are excellently able to dissolve the reactants used.

The solvent can in principle be used in any mixing ratio with the monomer composition, the initiator and optionally the other reactants, with addition in a mass proportion of 5% or more (based on the mass of the resulting overall formulation) being preferred. The range from 5% to 40% is particularly preferred since the use of solvent can be kept low. In addition, the range from 70% to 95% is particularly preferred, since this results in solutions with a low polyepoxide content and thus keeps the risk of gelling low becomes. The range from 40% to 70% is particularly preferred, as there is a good compromise between the amount of solvent and the risk of gelling.

An important process variable for controlling the molecular weight of the polyepoxides is temperature. Particularly preferred for essentially all embodiments is a polyepoxide according to the invention, wherein the polyepoxide can be produced by polymerizing the monomer composition, which is carried out at a temperature in the range from 50 to 150 ° C, preferably in the range from 60 to 130 ° C, whereby 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. The range from 50 to 90 °C is preferred because the reaction progress under these conditions is relatively slow and the reaction can be easily controlled, whereas the range between 90 and 120 °C is preferred because a balanced ratio of control and reaction rate is achieved .

ist, wobei das Polyepoxid bezogen auf die Masse des Polyepoxids umfasst:

• i.b) eine oder mehrere erste Monomereinheiten, in denen R für eine lineare oder verzweigte Alkylgruppe mit 1 bis 30 C-Atomen steht, in einem kombinierten Massenanteil von 50 % oder mehr, sowie
• ii.b) eine oder mehrere zweite Monomereinheiten, in denen R für einen linearen oder verzweigten organischen Rest mit 1 bis 30 C-Atomen steht, der zumindest eine reaktive funktionelle Gruppe umfasst, wobei R keine Epoxy-Gruppe umfasst, in einem kombinierten Massenanteil von 1 % oder mehr, und/oder
• iii.b) eine oder mehrere dritte Monomereinheiten, in denen R für einen linearen oder verzweigten organischen Rest mit 2 bis 30 C-Atomen steht, der zumindest eine Epoxy-Gruppe umfasst, in einem kombinierten Massenanteil von 1 % oder mehr.

The person skilled in the art 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, whereby the above statements regarding the underlying monomers apply accordingly. The invention is therefore closely related to a polyepoxide for use in reactive adhesives, the polyepoxide being a copolymer with a large number of monomer units of the formula (II):

is, 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 with 1 to 30 carbon 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 with 1 to 30 carbon atoms, which comprises at least one reactive functional group, where 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 with 2 to 30 carbon atoms, which comprises at least one epoxy group, in a combined mass fraction of 1% or more.

• a) Herstellen oder Bereitstellen einer Monomerzusammensetzung umfassend bezogen auf die Masse der Monomerzusammensetzung:
  • i) ein oder mehrere erste Monomere in einem kombinierten Massenanteil von 50 % oder mehr, wobei die ersten Monomere ausgewählt sind aus der Gruppe bestehend aus cycloaliphatischen monoepoxyfunktionellen Monomeren der Formel (I), wobei R für eine lineare oder verzweigte Alkylgruppe mit 1 bis 30 C-Atomen steht, sowie
  • ii) ein oder mehrere zweite Monomere in einem kombinierten Massenanteil von 1 % oder mehr, wobei die zweiten Monomere ausgewählt sind aus der Gruppe bestehend aus cycloaliphatischen monoepoxyfunktionellen Monomeren der Formel (I), wobei R für einen linearen oder verzweigten substituierten organischen Rest mit 1 bis 30 C-Atomen steht, der zumindest eine reaktive funktionelle Gruppe umfasst, und/oder
  • iii) ein oder mehrere dritte Monomere in einem kombinierten Massenanteil von 1 % oder mehr, wobei die dritten Monomere ausgewählt sind aus der Gruppe bestehend aus multiepoxyfunktionellen Monomeren der Formel (I), wobei R für einen linearen oder verzweigten substituierten organischen Rest mit 2 bis 30 C-Atomen steht, der zumindest eine Epoxy-Gruppe umfasst,

wobei die Formel (I):

entspricht, und

• b) Polymerisieren der Monomerzusammensetzung zum Erhalt des Polyepoxids, bevorzugt mittels kationischer Polymerisation.

What is disclosed in this respect is a process for producing a polyepoxide, preferably a polyepoxide according to the invention, comprising the 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, the first monomers being selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), where R represents a linear or branched alkyl group with 1 to 30 C -atoms stands, as well
  • ii) one or more second monomers in a combined mass fraction of 1% or more, the second monomers being selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), where R represents a linear or branched substituted organic radical with 1 to 30 carbon 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, the third monomers being selected from the group consisting of multiepoxy-functional monomers of the formula (I), where R represents a linear or branched substituted organic radical with 2 to 30 C atoms, which includes at least one epoxy group,

where formula (I):

corresponds, and

• b) polymerizing the monomer composition to obtain the polyepoxide, preferably by means of cationic polymerization.

In a preferred embodiment of the corresponding process, the polymerization is ended by an additional step after a predetermined reaction time or when a desired epoxy monomer conversion is reached. This can be done, for example, by cooling, diluting or adding a stopper. In order to optimally set the desired, low degree of branching and the desired molecular weights, a corresponding process is therefore preferred, the polymerization in process step b) being slowed down or stopped after the polymerization has begun by one or more slowing measures, the slowing down measure being selected from the group consisting of Cooling, diluting and adding 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.

A stopper reagent or stopper is a substance or a mixture of substances that interacts with the reactive species of a polymerization through a chemical reaction and thus prevents 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 from the time the stopper is added until the polymerization stops. In the context of the present invention, a stopper is a substance or a mixture which ensures that no further epoxy monomer conversion can be observed no later than 30 minutes after mixing. 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, imidazoline, (iso)quinoline, purine, Pyrimidine, 4-vinylpyridine or 4-ethylpyridine, with pyridine and 4-ethylpyridine being extremely preferred, and 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 the light of the above statements, a corresponding process is preferred, the polymerization in process step b) being carried out in such a way that an epoxy group conversion of 10% or more, preferably 30% or more, is achieved, the epoxy group conversion preferably being in the range is from 20 to 35%. If no third monomers are used whose second epoxy group is to be retained, a corresponding process is even preferred, with the polymerization in process step b) taking place in such a way that an epoxy group conversion of 50% or more, very particularly preferably 70% or more, particularly preferably 90% or more, is achieved, the epoxy group conversion preferably being in the range from 35 to 60% or in the range from 60 to 100%.

In addition, preferred embodiments for the corresponding process result from the above statements on the producibility of the polyepoxides according to the invention.

An analogous process is preferred, in which the polymerization of the monomer composition is initiated by a cationic initiator, the initiator preferably being 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.

A corresponding analogous process is therefore 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.

A corresponding analogous process is also preferred, with the polymerization of the monomer composition being carried out in a solvent.

A corresponding analogous process is therefore also preferred, with the polymerization of the monomer composition being carried out 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 at a temperature in the range from 50 to 90 °C or in the range between 90 and 120 °C.

A corresponding process is also preferred, with the process being carried out as a semi-batch or fed-batch process.

• c) Teilweises Vernetzen der Polyepoxide zur Steigerung des gewichtsmittleren Molekulargewichts Mw, wobei das Vernetzen zumindest teilweise, bevorzugt überwiegend, besonders bevorzugt im Wesentlichen vollständig, über die von zweiten Monomeren und/oder dritten Monomeren abgeleiteten Monomereinheiten, bevorzugt über die von zweiten Monomeren abgeleiteten Monomereinheiten, erfolgt.

Particularly in the case of the implementation of a preferred monomer composition which comprises second monomers, it is a great advantage of the corresponding process that the polyepoxides produced, if necessary, have the reactive functional groups, their concentration in the co-polymers, very precisely before use in an adhesive can be controlled, can be further networked in a controlled manner in order to improve the rheological properties. A corresponding process is therefore preferred, additionally comprising the process step:

• c) partial crosslinking of the polyepoxides to increase the weight-average molecular weight Mw, the crosslinking being carried out at least partially, preferably predominantly, particularly preferably essentially completely, via the monomer units derived from second monomers and/or third monomers, preferably via the monomer units derived from second monomers, he follows.

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

The curable adhesive according to the invention is curable. Due to the possibility of curing, the curable adhesive 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 longer period of time (according to ASTM definition: “bonding agents used for transferring required loads between adherends exposed to service environments typical for the structure involved”). These are adhesives for bonds that are subject to high chemical and physical stress and which, when cured, contribute to the strengthening of the adhesive tapes. In other words, it is a reactive adhesive.

With a view to the subsequent end use, it is particularly preferred if the curable adhesive is a pressure-sensitive adhesive, the setting of the cohesion of the adhesive necessary for the pressure-sensitive tack being advantageously promoted by the use of the polyepoxides according to the invention.

According to the expert understanding, a pressure-sensitive adhesive is an adhesive that has pressure-sensitive adhesive properties, ie the property of forming a permanent bond to an adhesive base even under relatively weak pressure. Corresponding pressure-sensitive adhesive tapes can usually be removed from the adhesive base after use essentially without leaving any residue and are usually permanently self-adhesive even at room temperature, which means that they have a certain viscosity and stickiness to the touch, so that they wet the surface of a substrate even with slight pressure. Without wishing to be bound to this theory, it is often assumed that a pressure-sensitive adhesive can be viewed as an extremely high-viscosity liquid with an elastic component, which therefore has characteristic viscoelastic properties that lead to the permanent inherent tack and pressure-sensitive adhesive ability 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 proportionate viscous flow serves to achieve adhesion, while the proportionate elastic restoring forces are necessary in particular to achieve cohesion. The connections 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 characterize the degree of elastic and viscous proportion, the storage modulus (G`) and the loss modulus (G'') are usually used, which are determined using dynamic mechanical analysis (DMA), for example using a rheometer, as described, for example, in WO 2015/189323 is revealed. In the context of the present invention, an adhesive is preferably understood to be pressure-sensitively tacky and thus a pressure-sensitive adhesive if, at a temperature of 23 ° C in the deformation frequency range of 10 ° to 10 ¹ rad / sec, G 'and G'' are each at least partially in the range of 10 ³ to 10 ⁷ Pa.

The usual initiators known to those skilled in the art can be used as initiators for the curable adhesives, with particular preference being given to the use of initiators which are disclosed above as being preferred with regard to the production of the polyepoxides.

It can be seen as an advantage of curable adhesives according to the invention that, in addition to the presence of the polyepoxides according to the invention, they are very flexible with regard to the use of typical additives, so that the physico-chemical properties can be further tailored to the requirements of the respective application. A curable adhesive according to the invention is therefore preferred, wherein the curable adhesive comprises one or more further additives, preferably in a combined mass proportion in the range from 0.1 to 50%, preferably in the range from 0.2 to 40%, based on the mass of Adhesive, and/or wherein the one or more further additives are preferably selected from the group consisting of adhesive resins, anti-aging agents, light stabilizers, UV absorbers, fillers and rheological additives.

The invention also relates to an adhesive tape comprising the curable adhesive composition according to the invention. The person skilled in the art understands that the adhesive tape according to the invention is a reactive adhesive tape and, in light of the above statements, is preferably a pressure-sensitive adhesive tape.

An adhesive tape according to the invention is preferred, wherein the adhesive tape comprises a carrier layer or a separating 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 which is arranged on the adhesive.

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

Preferred embodiments of the invention are further explained and described below with reference to experiments.

A. Sample preparation:

Polyepoxides E1 to E6 were produced. For this purpose, a screw cap glass equipped with a magnetic stirring bar and rubber septum was charged with the respective initiator (0.017 - 0.400 mol%, see Table 1) and this was dissolved in acetone, so that a 5% solution was created.

The monomer composition (ca. 5.0 g) and the solvent (ca. 5.0 g) were added, the jar was sealed and the reaction mixture was stirred for 5 min at room temperature. The polymerization was then carried out at the temperature given in Table 1 (80-110 ° C) and 200 rpm for t = 24 h and then ended by adding pyridine (ten times the amount of initiator) and cooled to room temperature.

The parameters used in production are summarized in Table 1. Table 1 sample Mono1 /% Mono2 /% Mono3 /% Lsgm. initiator c(lnit.)* / mol% T / °C t/h E1 90 10 - toluene CXC-1614 0.400 110 24 E2 90 - 10 toluene CXC-1614 0.030 110 24 E3 90 - 10 MEK CXC-1612 0.064 80 24 E4 90 10 - MEK CXC-1612 0.017 80 24 E5 90 10 - MEK CXC-1612 0.064 80 24 E6 90 10 - MEK CXC-1612 0.256 80 24 *Concentration of the initiator in mol% refers to the total of the epoxy monomers

The substances used here are listed in Table 2. Table 2 Mono1 3,4-Epoxycyclohexylcarboxylic acid methyl ester, CAS no. 41088-52-2; ECCM ; Cycloaliphatic epoxide with methyl ester function from Chemos Mono2 ((3,4-Epoxycyclohexyl)methyl)methacrylate, CAS no. 82428-30-6; TTA15 ; Cycloaliphatic epoxy with methacrylate function from Jiangsu Tetra New Materials Mono3 ((3,4-Epoxycyclohexyl)methyl-3,4-epoxycyclohexylcarboxylate, CAS No. 2386-87-0; Cycloaliphatic bis-epoxide from Cytec; CXC-1612 ((4-Methoxybenzyl)-dimethylphenyl)ammonium hexafluoroantimonate; latent cationic initiator based on blocked superacid “blocked acid catalyst” from King Industries, CXC-1614 ((4-Methoxybenzyl)-dimethylphenyl)ammonium triflate; Latent cationic initiator based on blocked super acid “blocked acid catalyst” from King Industries

B. Analysis

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

The molecular weight distribution of the resulting polymer solution was determined using GPC. The determination was carried out with degassed THF as mobile phase, 100 µL 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 PSS SDV 10 µm ID 8 mm × 50 mm guard column, a PSS SDV 10 µm 10 ³ Å ID 8 mm × 300 mm, a PSS SDV 10 µm 10 ⁵ Å ID 8 mm × 300 mm, a PSS SDV 10 µm 10 ⁷ Å ID 8 mm × 300 mm and a SECcurity differential refractometer detector (RI). The data were recorded and evaluated using the software PSS - WinGPC UniChrome Version 8.33. The calibration was carried out using polystyrene standards, which are universally converted into a poly(methyl methacrylate) calibration using the Mark Houwink coefficients K and α. By obtaining a GPC result, the solubility criterion of the polyepoxides according to the invention is also met. This shows that the polyepoxides present here are uncrosslinked.

The epoxy conversion was determined using FTIR or NMR, depending on the substance observed.

For Mono1, the shrinkage of the epoxy band in the IR spectrum was used to quantify the time-dependent epoxy monomer conversion. For this purpose, the integral ratio of the epoxy band (778 to 812 cm-1) and carbonyl band (1650 to 1800 cm-1) was formed. 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) could therefore be obtained from the following relationship: $$U\left(t\right)=\left(1-\frac{verH\ddot{a}ltnisd.InteGrale\frac{EpOxy}{CarbOnyl}\left(t\right)}{verH\ddot{a}ltnisd.InteGrale\frac{EpOxy}{CarbOnyl}\left(t=0\right)}\right)\ast 100\%$$

For Mono2, the growth of the polyether band in the IR spectrum was used to quantify the time-dependent epoxy monomer conversion. 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 one Epoxy monomer conversion U(t) was determined using a correlation equation created by calibration with conversion determined by NMR spectroscopy: $$U\left(t\right)=\left(\mathrm{46,718}\ast \left(verHaltnisd.InteGrale\frac{EpOxy}{CarbOnyl}\right)-\mathrm{29,584}\right)\ast 100\%$$

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 evaluation. ¹ H NMR spectra of samples dissolved in CDCI ₃ were recorded on a Bruker AVIII (300 MHz) or Bruker AVII+ (500 MHz) with a 10 mm BBO / 5 mm BBFO probe head. The TopSpin software was used for the evaluation.

The results obtained are summarized in Table 3. Table 3 sample Final sales /% Mw / (g/mol) PDI E1 >99 5100 6.9 E2 >99 4200 4.3 E3 100 1000 2.5 E4 100 19000 10.0 E5 100 24000 72.8 E6 100 58600 231.1

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

The person skilled in the art recognizes the advantageous properties of the polyepoxides according to the invention from 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 the crosslinking points along the polyepoxide polymer chain . In particular, the person skilled in the art recognizes that the polyepoxides according to the invention can be used advantageously for the construction of reactive pressure-sensitive adhesives, since the polyepoxide according to the invention can first be used to formulate a pressure-sensitive adhesive, which can then be processed into a pressure-sensitive adhesive tape, which after application of the pressure-sensitive adhesive tape in another step can be cured.

In contrast, epoxy adhesives according to the prior art are generally applied and cured in one 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 have the disadvantages explained above that are easily recognizable to those skilled in the art.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 3101047 A1 [0009]
• US 6908722 B1 [0070]
• US 3729313 A [0070]
• US 3741769 A [0070]
• US 4250053 A [0070]
• US 4231951 A [0070]
• US 4256828 A [0070]
• US 4058401 A [0070]
• EP 0542716 B1 [0072]
• WO 2015/189323 [0095]

Non-patent literature cited

• DIN EN ISO 11357-3:2013-04 [0069]

Claims (10)

Polyepoxide for use in reactive adhesives, wherein the polyepoxide can be produced 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, the first monomers being selected from Group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), where R represents a linear or branched alkyl group with 1 to 30 carbon atoms, and ii) one or more second monomers in a combined mass fraction of 1% or more, the second Monomers are selected from the group consisting of cycloaliphatic monoepoxy-functional monomers of the formula (I), where R represents a linear or branched organic radical with 1 to 30 carbon atoms, which comprises at least one reactive functional group, and / or iii) one or several third monomers in a combined mass fraction of 1% or more, the third monomers being selected from the group consisting of multiepoxy-functional monomers of the formula (I), where R represents a linear or branched organic radical with 2 to 30 carbon atoms, which comprises at least one epoxy group, the formula (I):

corresponds. Polyepoxide after Claim 1 , wherein the monomer composition comprises second monomers. Polyepoxide according to one of the Claims 1 or 2 , wherein the monomer composition comprises third monomers. Polyepoxide according to one of the Claims 1 until 3 , where the polyepoxide in toluene has a mass-related gel content of 10% or less. Polyepoxide according to one of the Claims 1 until 4 , wherein the polyepoxide has a weight average molecular weight M _w (GPC) of 500,000 g / mol or less. Polyepoxide according to one of the Claims 1 until 5 , wherein the polyepoxide can be produced by polymerizing the monomer composition, which is initiated by a cationic initiator. Polyepoxide according to one of the Claims 1 until 5 , wherein the polyepoxide can be produced by polymerization of the monomer composition, which is carried out in a solvent. Polyepoxide according to one of the Claims 1 until 7 , wherein the polyepoxide can be produced by polymerizing the monomer composition, which is carried out at a temperature in the range from 50 to 150 ° C Curable adhesive composition comprising a polyepoxide according to one of Claims 1 until 8th . Adhesive tape, comprising a curable adhesive Claim 9 .