EP4100448A1

EP4100448A1 - High tg acrylate copolymers with nitrogen-containing aromatic heterocyclic group

Info

Publication number: EP4100448A1
Application number: EP21701690.6A
Authority: EP
Inventors: Christian Schuh; Helmut Ritter; Laura Hartmann; Monir Tabatabai; Philipp Reuther
Original assignee: Tesa SE
Current assignee: Tesa SE
Priority date: 2020-02-04
Filing date: 2021-01-14
Publication date: 2022-12-14
Also published as: US20230064702A1; DE102020201334A1; CN115052912B; CN115052912A; WO2021156033A1

Abstract

The invention relates to a process for the radical polymerization for preparing a copolymer, using specific monomers A, which have a glass transition temperature Tg of at least 0° and specific monomers B, which contain an aromatic heterocyclic group that contain at least one nitrogen atom in the ring. The invention also relates to copolymers that are obtained by the radical polymerization, to the use of same as accelerators in a curing reagent for adhesive compounds, and to adhesive strips containing same.

Description

High Tg acrylate copolymers with nitrogen-containing aromatic heterocyclic

group

The invention relates to a process for radical polymerization for the production of a copolymer with specific monomers A which have a Tg of at least 0 ° C. and specific monomers B which contain an aromatic heterocyclic group which contain at least one nitrogen atom in the ring. The invention further relates to the copolymers which are obtained by free radical polymerization, the use of these as accelerators in the curing reagent for adhesives and adhesive tapes which contain them.

For reactive adhesive tapes, which can be produced both from solution and from the melt, storable temperature- and / or solvent-resistant polymers are required as accelerators for the curing reaction. Many of the systems commercially available to date contain substituted imidazoles or urea derivatives.

In the prior art, for example, the following accelerators are known:

CN 106432584 A discloses acrylate copolymers with imidazole groups, which otherwise consist of low-Tg comonomers such as HEA (-20 ° C), EHA (-58 ° C) and LA (-17 ° C). The typical “rubber-toughening” materials to which this application relates are based on phase-separated low-Tg polymers that can absorb impacts on the hard epoxy network.

CN 104387525 A1 discloses terpolymers made from three different monomers. The polymers contain monomers in proportions of more than 10 mol% which, as homopolymer, have a Tg lower than 0 ° C. Furthermore, the process requires that an epoxy polymer is first produced, to which an imidazole derivative is bound in a second step.

US 2002098361 A1 describes copolymers made from monomers of N-vinyl derivatives and acrylates. The homopolymers of the acrylates should have a Tg of less than 0 ° C. The reference does not disclose a copolymer in which a monomer having a Tg of at least 0 ° C, is used in at least 30 mol%. The polymers obtained in this publication are low Tg polymers, since they are pressure-sensitive adhesives.

The US 4,071,653 discloses acrylate copolymers, which from at least 50%

Methyl methacrylate monomers and up to 10% vinyl pyrrolidone, amides, methylolamides, methyloletheramides can exist. Monomers with aromatic heterocyclic nitrogen-containing groups are not disclosed.

US 2011159195 A1 describes acrylate pressure-sensitive adhesives, the polymers being low Tg polymers. The polymers by way of example all have a 2-ethylhexyl acrylate of at least 70%, which, as a homopolymer, has a Tg of approx. -56 ° C.

US 2013/190468 A1 discloses low Tg polymers which contain between 30 and 70% of a low Tg monomer. Furthermore, no monomers with heteroaromatic groups which contain nitrogen are disclosed.

It can be perceived as disadvantageous that the abovementioned polymers are not suitable as accelerators which are exposed to high temperatures in the production process. Particularly when manufacturing adhesive tapes from the melt, more energy is introduced into the system than with conventional reactive liquid adhesives. Most of the previously known accelerators do not survive an extrusion step at up to 100 ° C, which prevails in the production from the melt, or are not active enough in their property as accelerators in the final curing. The object of the present invention was therefore to provide a stable accelerator, in particular at 100 ° C., which, despite the high temperature stability, has a sufficient accelerating effect, in particular on an epoxy-dicyanamide reaction.

The object could be achieved by the specific copolymers of the present invention and their production process.

Accordingly, in a first aspect, the invention relates to a process for free-radical polymerization for the production of a copolymer, comprising or consisting of the step: Polymerizing at least one monomer A which contains at least one unsaturated -C = C double bond and has a T _g > 0 ° C., determined on the basis of the homopolymer of the monomer A by means of DSC measurement; at least one monomer B which contains an aromatic heterocyclic group which contains at least one nitrogen atom in the ring and which furthermore contains at least one unsaturated -C = C double bond; and optionally at least one monomer C which contains at least one unsaturated -C =C double bond and is different from monomers A and B; in the presence of at least one free radical initiator and optionally at least one regulator; wherein the at least one monomer A is contained in at least 30 mol% based on the total monomers of the copolymer.

In a second aspect, the invention relates to a copolymer obtainable by free radical polymerization according to the present invention.

In a third aspect, the invention relates to an adhesive tape comprising at least one layer of a pressure-sensitive adhesive, the adhesive comprising a polymeric film-forming matrix and a curable composition, the curable composition comprising one or more epoxy resins and at least one curing reagent for epoxy resins, characterized in that that the curing reagent comprises at least one copolymer of the present invention and at least one curing agent.

Finally, in a fourth aspect, the present invention relates to the use of the copolymer of the present invention as an accelerator in the curing reagent for adhesives.

“At least one” as used herein refers to 1 or more, for example 2, 3, 4, 5, 6, 7, 8, 9 or more. In connection with constituents of the compounds described herein, this indication does not refer to the absolute amount of molecules, but to the type of constituent. “At least one monomer A” therefore means, for example, that only one type of monomer A or several different types of monomers A can be included without specifying the amount of the individual compounds. Unless stated otherwise, all of the quantitative data given in connection with the compositions described herein relate to% by weight in each case based on the total weight of the composition. Furthermore, quantities of this type which relate to at least one constituent always relate to the total amount of this type of constituent contained in the composition, unless explicitly stated otherwise. This means that such quantitative data, for example in connection with “at least one monomer A”, relates to the total amount of monomers A contained in the reaction or in the polymer, unless explicitly stated otherwise.

Numerical values that are given herein without decimal places refer to the full stated value with one decimal place. For example, “99%” stands for “99.0%”.

The expressions “approximately” “approximately” or “about” in connection with a numerical value refer to a variance of ± 10% based on the specified numerical value, preferably ± 5%, particularly preferably ± 1%, even more preferably below ± 0.1%.

Numeric ranges given in the format "in / from x to y" include the stated values. If several preferred numeric ranges are given in this format, it is understood that all ranges created by the combination of the various endpoints are also recorded.

Information on the molecular weight relates to the weight average molecular weight in g / mol, unless the number average molecular weight is explicitly mentioned. Molecular weights are preferably determined by GPC using polystyrene standards.

These and other aspects, features and advantages of the invention will become apparent to those skilled in the art from a study of the following detailed description and claims. Each feature or each embodiment from one aspect of the invention can be used in any other aspect of the invention. For example, described features or embodiments of the method can also be applied to the claimed copolymer, and vice versa. Furthermore, it goes without saying that the examples contained herein are intended to describe and illustrate the invention, but not to restrict it, and in particular the invention is not limited to these examples. The present invention relates in particular to a process for radical polymerization for the production of a copolymer, comprising or consisting of the step: polymerizing at least one monomer A which contains at least one unsaturated -C = C double bond and a T _g > 0 ° C, preferably> 40 ° C., more preferably> 70 ° C., most preferably> 90 ° C., determined on the basis of the homopolymer of monomer A by means of DSC measurement; at least one monomer B which contains an aromatic heterocyclic group which contains at least one nitrogen atom in the ring and which furthermore contains at least one unsaturated - C =C double bond; and optionally at least one monomer C which contains at least one unsaturated -C = C double bond and is different from monomers A and B, and preferably in less than 10 mol%, more preferably less than 5 mol%, most preferably 0 mol% based on the total monomers of the copolymer is contained; in the presence of at least one free radical initiator and optionally at least one regulator; wherein the at least one monomer A is contained in at least 30 mol% based on the total monomers of the copolymer.

The at least one monomer A can preferably have a molecular weight of less than 1000 g / mol, more preferably less than 750 g / mol, most preferably less than 500 g / mol.

The at least one monomer A is different from the at least one monomer B and, if present, from the at least one monomer C. In a preferred embodiment, the at least one monomer A does not comprise any nitrogen-containing aromatic heterocyclic group.

The at least one monomer A is preferably selected from acenaphthylene, maleic anhydride, N-phenylmaleimide, N-vinylpyrrolidone, 2-vinylnaphthalene acrylamide, N-vinylcaprolactam, itaconic anhydride, tert-butyl methacrylate, dihydrodicyclopentadienyl acrylate, dihydrodicyclopentadienyl acrylate, acrylic acid, tert-acrylate, methyl acrylate, tert-acrylate, butyl acrylate, acrylic acid, tert-acrylate, acrylate, acrylate, acrylic ,. Styrene and styrene derivatives such as 4-acetoxystyrene, alpha-methylstyrene, 3-methylstyrene, 4-methylstyrene, N, N-dimethylacrylamide, N-tert-butyl acrylamide, N-isopropyl acrylamide, isobornyl acrylate, acrylonitrile, methacrylonitrile, hydroxyethyl methacrylate, cyclohexyl methacrylate, tert-tertiary

Butylcyclohexyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, glycidyl methacrylate, Ethyl methacrylate, benzyl methacrylate, phenyl methacrylate, iso-butyl methacrylate, stearyl acrylate, vinyl acetate, n-butyl methacrylate, methyl acrylate, 2-phenoxyethyl acrylate, 2- (3-

Toloidylureido) ethyl methacrylate or mixtures thereof.

In an alternative preferred embodiment, the at least one monomer A is selected from acenaphthylene, maleic anhydride, N-phenylmaleimide, N-vinylpyrrolidone, 2-vinylnaphthalene, acrylamide, N-vinylcaprolactam, itaconic anhydride, tert-butyl methacrylate,

Dihydrodicyclopentadienyl acrylate, isobornyl methacrylate, tert-butyl acrylate, acrylic acid, methyl methacrylate, styrene and styrene derivatives such as 4-acetoxystyrene, 3-methylstyrene, 4-methylstyrene, N, N-dimethyl acrylamide, N-tert-butyl acrylamide, N-isopropyl acrylamide,

Isobornyl acrylate, acrylonitrile, methacrylonitrile, hydroxyethyl methacrylate, cyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, glycidyl methacrylate, ethyl methacrylate, benzyl methacrylate, phenyl methacrylate or mixtures thereof, iso-butyl methacrylate, (3-ethyl) tolacrylate, phenyl methacrylate or mixtures thereof (3-butyl methacrylate (3-ethyl) methacrylate (3-ethyl) methacrylate (3-ethyl) methacrylate, cyclohexyl methacrylate, tert-butyl methacrylate.

Dihydrodicyclopentadienyl acrylate, isobornyl methacrylate, tert-butyl acrylate, acrylic acid,

Methyl methacrylate, styrene and styrene derivatives such as 4-acetoxystyrene, 3-methylstyrene, 4-methylstyrene, N, N-dimethylacrylamide, N-tert-butylacrylamide, N-isopropylacrylamide,

Isobornyl acrylate, acrylonitrile, methacrylonitrile, hydroxyethyl methacrylate, cyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, phenyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, glycidyl methacrylate, 2- (3-toloidylureido) ethyl methacrylate, or mixtures thereof.

In an alternative preferred embodiment, the at least one monomer A is selected from acenaphthylenes, maleic anhydride, N-phenylmaleimide, N-vinylpyrrolidone, 2-vinylnaphthalene, acrylamide, N-vinylcaprolactam, itaconic anhydride, tert-butyl methacrylate,

Isobornyl acrylate, acrylonitrile, methacrylonitrile, phenyl methacrylate, 2- (3-toloidylureido) ethyl methacrylate, or mixtures thereof. In a further alternative preferred embodiment, at least two different types of monomer A are present. In a more preferred embodiment, a monomer A is N-phenylmaleimide and the further monomer A is selected from acenaphthylenes, maleic anhydride, N-vinylpyrrolidone, 2-vinylnaphthalene, acrylamide, N-vinylcaprolactam, itaconic anhydride, tert-butyl methacrylate, dihydrodicyclopentadienyl acrylate,

Isobornyl methacrylate, tert-butyl acrylate, acrylic acid, methyl methacrylate, styrene and styrene derivatives such as 4-acetoxystyrene, alpha-methylstyrene, 3-methylstyrene, 4-methylstyrene, N, N-dimethylacrylamide, N-tert-butylacrylamide, N-isopropylacrylamide, isobornyl acrylate, Acrylonitrile, methacrylonitrile, hydroxyethyl methacrylate, cyclohexyl methacrylate, tert-

Butylcyclohexyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, glycidyl methacrylate, ethyl methacrylate, benzyl methacrylate, phenyl methacrylate, iso-butyl methacrylate, stearyl acrylate, vinyl acetate, n-butyl methacrylate, methyl acrylate and 2-phenoxyethyl acrylate, 2- (3-ido) ethyl acrylate.

The at least one monomer A is preferably contained in 30 to 70 mol%, more preferably 35 to 60 mol%, in particular 35 to 60 mol%, based on the total monomers of the copolymer.

The at least one monomer B contains an aromatic heterocyclic group which contains at least one nitrogen atom in the ring and furthermore at least one unsaturated -C = C double bond. For the purposes of the present invention, the unsaturated -C =C bond is not part of the ring of the aromatic heterocyclic group. In a preferred embodiment, this is a terminal -C = CH ₂ or -CCH ₃ = CH 2 group. These radicals can directly replace a hydrogen atom on the aromatic heterocyclic group or be bonded to the aromatic heterocyclic group via a spacer group.

The at least one monomer B preferably has a molecular weight of less than 2000 g / mol, preferably less than 1500 g / mol, more preferably less than 1000 g / mol.

In a preferred embodiment, the at least one monomer B contains, as an aromatic heterocyclic group which contains at least one nitrogen atom in the ring, imidazole, pyridine or derivatives thereof, more preferably imidazole or derivatives thereof. For the purposes of the present invention, the respective derivatives of pyridine and imidazole are derived, with one or more Hydrogen atoms can be replaced by alkyl radicals or other organic groups such as, for example, ketone or aldehyde radicals, in particular methyl, ethyl, propyl, butyl, pentyl and hexyl.

In a further preferred embodiment, the aromatic heterocyclic group of the monomer B, which contains at least one nitrogen atom in the ring, is substituted by a spacer group, in particular by a substituted or unsubstituted alkyl group, a substituted or unsubstituted -C (= 0) -alkyl group-, a substituted one unsubstituted -C (= 0) -alkyl-NH- C (= 0) -NH- group, having 2 to 20, preferably 2 to 6, more preferably 2 to 4 atoms, bonded to the polymer backbone of the copolymer obtained. If present, the spacer group binds to the polymer backbone via the carbon atom of the -C (= 0) unit of the respective group. Substituted here means that one or more hydrogen atoms of the respective alkyl unit can be replaced by -F, -Cl, -Br, -CH ₃ , -CH ₂ CH ₃ , -OH or -CF ₃ . An unsubstituted alkyl unit is preferably present in each case.

In a preferred embodiment, the terminal -CH = CH ₂ or -CCH ₃ = CH ₂ group in the monomer B is replaced by a spacer group, in particular by a substituted or unsubstituted alkyl group, a substituted or unsubstituted -C (= 0) -alkyl group-, a substituted or unsubstituted -C (= 0) -alkyl-NH-C (= 0) -NH- group, with 2 to 20 or 2 to 10, preferably 2 to 6, more preferably 2 to 4 atoms, to the aromatic heterocyclic group bound, the spacer group replacing a hydrogen atom of the aromatic heterocyclic group. If present, the spacer group binds via the carbon atom of the -C (= 0) - unit of the respective group to the -CH = CH ₂ or -CCH ₃ = CH ₂ group, that is to say (meth) acrylate monomers are present. Substituted here means that one or more hydrogen atoms of the respective alkyl unit can be replaced by -F, -Cl, -Br, -CH ₃ , _{-CH 2} CH ₃ , -OH or -CF ₃ . An unsubstituted alkyl unit is preferably present in each case.

In the context of the invention, the backbone is understood to be the longest chain of the polymer which results from the polymerization of the unsaturated double bonds of monomers A and B and optionally C.

In the following a non-limiting example for the backbone and a spacer group with 4 atoms is shown: Backbone spacer group with 4 atoms

In a preferred embodiment, the monomer B does not contain an —OH radical.

In a preferred embodiment, the at least one monomer B is selected from imidazole ethyl methacrylate, imidazole ethyl acrylate, 2-methylimidazole ethyl methacrylate, 2-methylimidazole ethyl acrylate, methylaminopyridine ethyl methacrylate, methylaminopyridine ethyl acrylate, vinylimidazole, imidazole ethyl urethane methacrylate) or mixtures thereof, N-methyl-4-methyl-N-ethyl-methacrylate, N-methyl-N-methyl-urethane methacrylate, N-methyl-N-methyl-N-ethyl acrylate, N-methyl in particular imidazole ethyl methacrylate, imidazole ethyl acrylate, 2-methylimidazole ethyl methacrylate, 2-methylimidazole ethyl acrylate,

Methyl aminopyridine ethyl methacrylate, methyl aminopyridine ethyl acrylate, or mixtures thereof.

The at least one monomer B is preferably contained in 20 to 70 mol%, more preferably 25 to 60 mol%, in particular 35 to 60 mol%, based on the total monomers of the copolymer.

In a preferred embodiment, the monomers A to the monomers B are present in a molar ratio of 30 to 60 to 40 to 70, preferably 40 to 60 to 40 to 60.

The monomers C are preferably monomers with a Tg of less than 0 ° C. These also contain an unsaturated -C = C- group, preferably a terminal - CH = CH ₂ or -CCH ₃ = CH ₂ group. In a preferred embodiment, essentially no monomers C are contained, in particular no monomers C are contained.

The reaction takes place in the presence of at least one free radical initiator. All radical initiators known to the person skilled in the art in the field of radical polymerization are suitable. These include UV radical initiators, which are activated by means of UV radiation, and thermal radical initiators, which are thermally activated. Are particularly suitable Free radical initiators that are used for the polymerization of (meth) acrylates. In a preferred embodiment, the at least one free-radical initiator is azobisisobutyronitrile.

In a preferred embodiment, the at least one free radical initiator is present in less than 10 mol%, preferably in at most 5 mol%, based on the sum of the monomers A to C, which is 100 mol%.

The reaction is preferably carried out in at least one organic solvent, preferably selected from toluene, acetone, butanone, ethyl acetate, 2-propanol, dimethylformamide and mixtures thereof.

Furthermore, the reaction is preferably carried out under a protective gas atmosphere, in particular under a nitrogen or argon atmosphere.

At least one regulator can also be used in the reaction; this is preferably mercaptoethanol. In a preferred embodiment, the at least one regulator is contained preferably in less than 10 mol%, preferably in at most 5 mol%, based on the sum of the monomers A to C, which are 100 mol%.

The polymerization is preferably carried out with heating, more preferably at a temperature of at least 35 ° C, even more preferably at least 50 ° C, most preferably at least 65 ° C, the temperature preferably not being higher than 120 ° C. In a preferred embodiment, the reaction time is at least 1 hour, preferably at least 6 hours, more preferably at least 22 hours.

The free radical polymerization of the present invention will contain a copolymer, which is also an object of the invention.

The copolymer obtained preferably has a Tg of 40 to 200 ° C., measured by means of DSC. A Tg which is at least 20 ° C. above the processing temperature is preferred, in particular for shelf life. If the reactive adhesive is processed at 80 ° C., the Tg of the copolymer is correspondingly preferably greater than 100 ° C., but in order to achieve the highest possible reactivity, the Tg of the copolymer is ideally lower than the curing temperature. This means that at a curing temperature of 160 ° C, 140 ° C or, for example, 130 ° C, the Tg is correspondingly less than 160 ° C, less than 140 ° C or less than 130 ° C. The Tg is also preferably at least 20 ° C higher than the storage temperature, ie the Tg for room temperature storage (20 ° C) is at least 40 ° C. If higher temperatures are reached in the transport process, the Tg is correspondingly preferably 60 ° C, in particular 80 ° C. Furthermore, the copolymer preferably has a weight-average molecular weight Mw of at least 1000 g / mol, more preferably 2000 g / mol. A particularly good compromise between long shelf life and reactivity is achieved if the molecular weight is not greater than 500,000 g / mol, in particular 200,000 g / mol, and is preferably between 2000 and 100,000 g / mol.

The inventive copolymer obtained is used as an accelerator in the curing reagent for adhesives, in particular epoxy-based adhesives.

The invention further relates to an adhesive tape comprising at least one layer of a pressure-sensitive adhesive, the adhesive comprising a polymeric film-forming matrix and a curable composition, the curable composition comprising one or more epoxy resins and at least one curing reagent for epoxy resins, characterized in that the curing reagent comprises at least one copolymer according to the present invention and at least one hardener.

In a preferred embodiment, at least one of the epoxy resins of the curable composition is an elastomer-modified, in particular nitrile rubber-modified epoxy resin, and / or a fatty acid-modified epoxy resin.

In a further preferred embodiment, one or more thermoplastic polyurethanes or one or more non-thermoplastic elastomers are used wholly or partially as the polymeric film-forming matrix.

In the following part, which relates to the adhesives, the copolymers of the present invention are also referred to as accelerators.

Advantageously, for example, 5 to 80 parts by weight of at least the polymeric film-forming agent matrix (M) and 20 to 95 parts by weight of the one epoxy resin or the sum total Epoxy resins are used when the parts by weight of the film-forming matrix and the epoxy resins add up to 100. The preferred amount of hardening reagent to be used can vary depending on the copolymer used and, if appropriate, hardeners, see further below in this regard. For the purposes of the present invention, a hardening reagent contains at least one copolymer, that is to say accelerator, of the present invention and at least one hardener.

The curing of the adhesive, also referred to here as a curable composition, takes place in particular via the reaction of one or more reactive resins with one or more copolymers and hardeners according to the invention. The curable composition comprises at least one epoxy resin as reactive resin, but can also comprise several epoxy resins. The one epoxy resin or the several epoxy resins can be the only reactive resins in the curable composition, in particular the only components of the curable composition that can lead to curing of the composition with the curing reagent - if necessary after appropriate activation. In principle, however, it is also possible for further reactive resins that are not epoxy resins to be present in addition to the epoxy resin or in addition to the epoxy resins.

The epoxy resin (s) used are, for example and advantageously, one or more elastomer-modified, in particular nitrile rubber-modified, epoxy resins and / or one or more silane-modified epoxy resins and / or one or more fatty acid-modified epoxy resins.

Reactive resins are crosslinkable resins, namely oligomers or short-chain polymeric compounds comprising functional groups, in particular with a number-average molar mass M _n of not more than 10,000 g / mol; and in particular those with several functional groups in the macromolecule. Since the resins are a distribution of macromolecules of different individual masses, the reactive resins can contain fractions whose number-average molar mass is significantly higher, for example up to about 100,000 g / mol; this applies in particular to polymer-modified reactive resins, such as elastomer-modified reactive resins.

Reactive resins differ from tackifier resins frequently used for adhesives, in particular for pressure-sensitive adhesives. According to the general understanding of the art, an “adhesive resin” is understood to mean an oligomeric or polymeric resin that only the adhesion (the tack, the inherent tack) of the PSA in comparison to none Increased pressure sensitive adhesive containing adhesive resin but otherwise identical. Typically, apart from double bonds (in the case of the unsaturated resins), adhesive resins contain no reactive groups, since their properties should not change over the life of the pressure-sensitive adhesive.

The functional groups of the reactive resins are such that, under suitable conditions - in particular after activation, for example by increased temperature (thermal energy) and / or by actinic radiation (such as light, UV radiation, electron beams, etc.) and / or by initiation and / or catalysis by further chemical compounds, such as water (moisture-curing systems) - with a curing reagent lead to curing of the composition comprising the reactive resins and the curing reagent, in particular in the sense of a crosslinking reaction.

In the context of this document, epoxy resins are reactive resins comprising epoxy groups, in particular those with more than one epoxy group per molecule, that is to say those reactive resins in which the functional groups or at least some of the functional groups are epoxy groups. The conversion of the epoxy resins during the hardening reaction of the hardenable composition takes place in particular via polyaddition reactions with suitable epoxy hardeners or via polymerization via the epoxy groups. Depending on the choice of epoxy hardener, both reaction mechanisms can take place in parallel.

In this document, in accordance with DIN 55945: 1999-07, the hardener is the chemical compound (s) that act as a binder and that is (are) added to the crosslinkable resins in order to ensure the hardening (crosslinking) of the curable composition, in particular in the form of an applied film. In the curable compositions, hardener is accordingly the designation for that component which, after being mixed with the reactive resins and activated accordingly, brings about the chemical crosslinking.

In the context of this document, accelerators are those chemical compounds which, in the presence of another hardener, increase the reaction rate of the hardening reaction and / or the rate of activation of the hardening of the epoxy resins, in particular in the sense of a synergism. The hardener system of the present invention contains at least one copolymer according to the present invention as accelerator. duct tape

The curable composition of the adhesive tape according to the invention is preferably an adhesive, in particular a reactive adhesive, particularly preferably an adhesive or reactive adhesive which is pressure-sensitive at room temperature (23 ° C.).

Adhesives are (according to DIN EN 923: 2008-06) non-metallic substances that connect parts to be joined through surface adhesion and internal strength (cohesion). Adhesives can be self-adhesive and / or develop their final bond strength only through certain activation, for example through thermal energy and / or actinic radiation. Reactive adhesives (which can be self-adhesive or non-adhesive before activation) comprise chemically reactive systems which, when activated, lead to a curing reaction and can develop particularly high adhesive strengths (in particular greater than 1 MPa) to the substrates to which they are bonded.

The hardening or solidification is achieved through a chemical reaction of the building blocks with one another. In contrast to pressure-sensitive adhesives, which are also regularly crosslinked to increase cohesion, but still have viscoelastic properties after crosslinking and, in particular, no longer experience solidification after bonding, with reaction adhesives, as a rule, curing leads to the actual bonding with the desired bond strengths; the adhesive itself is often thermoset or largely thermoset ("paint-like") after curing.

With the attribute "pressure-sensitive" - also as a component of nouns such as in pressure-sensitive adhesive - or synonymously with the attribute "self-adhesive" - also as a component of nouns - in the context of this document, those compositions are referred to that are already under relatively weak pressure - if if not stated otherwise, at room temperature, i.e. 23 ° C - allow a permanent connection with the primer and can be removed from the primer after use, essentially without leaving any residue. Pressure-sensitive adhesives are preferably used in the form of adhesive tapes. For the purposes of the present invention, a pressure-sensitive adhesive tape has a bond strength in the uncured state of at least 1 N / cm. The bond strength here is determined on steel analogously to ISO 29862: 2007 (method 3) at 23 ° C. and 50% relative humidity at a peel speed of 300 mm / min and a peel angle of 180 °. An etched PET film with a thickness of 36 μm, as is available from Coveme (Italy), is used as the reinforcement film. Gluing a 2 cm wide The measuring strip is made using a rolling machine weighing 4 kg at a temperature of 23 ° C. The tape is peeled off immediately after application. The measured value (in N / cm) was the mean value from three individual measurements.

Pressure-sensitive adhesives thus have a permanently tacky effect at room temperature, that is to say they have a sufficiently low viscosity and high tack so that they wet the surface of the respective adhesive base even with a slight pressure. The adhesiveness of the pressure-sensitive adhesives is based on their adhesive properties and the redetachability on their cohesive properties.

Pressure-sensitive reactive adhesives have pressure-sensitive adhesive properties at room temperature (and are especially viscoelastic in this state), but exhibit the behavior of reactive adhesives during and after curing.

According to the invention, the curable composition, in particular the pressure-sensitive adhesive, is used in film or preferably in layer form as a component of an adhesive tape.

For this purpose, the curable composition, in particular the pressure-sensitive adhesive, is preferably applied as a layer to a permanent or a temporary carrier, in particular using the coating processes known to the person skilled in the art. The coating of the web-like material is preferably carried out solvent-free, for example by means of nozzle coating or with a multi-roller applicator. This can be done particularly effectively and advantageously with a 2- to 5-roller applicator, for example with a 4-roller applicator, so that the self-adhesive mass is shaped to the desired thickness when passing through one or more roller gaps before transfer to the web-like material. The rollers of the applicator can be individually tempered, for example set to temperatures of 20 ° C to 150 ° C.

Permanent carriers are, in particular, permanent components of single- or double-sided adhesive tapes in which one or both of the outer surfaces of the adhesive tape is formed by an (pressure-sensitive) adhesive layer. For better handling, the adhesive layers can be covered with anti-adhesive separating layers, such as siliconized papers, which are removed in each case for bonding.

The general expression “adhesive tape” thus encompasses, on the one hand, a carrier material which is provided with an (pressure-sensitive) adhesive on one or both sides and can optionally have further layers in between. In particular, the term “adhesive tape” in the context of the present invention encompasses so-called “transfer adhesive tapes”, that is to say adhesive tapes without a permanent carrier, in particular single-layer adhesive tapes without a permanent carrier.

Such adhesive transfer tapes according to the invention are applied to a temporary carrier prior to application. In particular, flexible sheet-like materials (plastic films, papers or the like) which are provided with a separating layer (for example siliconized) and / or have anti-adhesive properties (so-called separating materials, liners or release liners) serve as temporary carriers.

Temporary carriers are used in particular to make single-layer or otherwise non-self-supporting adhesive tapes - that is, in particular only composed of the (pressure-sensitive) adhesive layer - manageable and to protect.

The temporary carrier can be easily removed and is removed during use (usually after the free adhesive tape surface has been applied to the first substrate and before the other, initially covered, adhesive tape surface is bonded to the second substrate), so that the adhesive layer is used as a double-sided adhesive tape can be. Adhesive transfer tapes according to the invention can, before application, also have two temporary carriers, between which the adhesive is present as a layer. For application, a liner is then regularly first removed, the adhesive applied and then the second liner removed. The adhesive can thus be used directly to connect two surfaces. Such carrierless adhesive transfer tapes are particularly preferred according to the invention. With such a tacky, backing-free adhesive transfer tape according to the invention, an adhesive bond that is very precise in terms of positioning and dosing is made possible.

Adhesive tapes are also possible in which one does not work with two liners, but with a single liner equipped with double-sided separation. The upper side of the adhesive tape web is then covered with one side of a double-sided separating liner, its underside with the back of the double-sided separating liner, in particular an adjacent turn on a bale or roll.

In particular, adhesive tapes differ - regardless of whether they have a carrier or are without a carrier, i.e. adhesive transfer tapes - from layers of adhesive that are present on a substrate as a liquid adhesive, for example, in that the adhesive tapes are self-supporting, i.e. can be handled as an independent product. To this end, the The layer of adhesive has sufficient cohesion on and / or the entirety of the layers forming the adhesive tape, in particular, sufficient stability.

Adhesive tapes that are coated on one or both sides with adhesives are usually wound or cross-wound into a roll in the form of an Archimedean spiral at the end of the manufacturing process. In order to prevent the adhesives from coming into contact with one another in the case of double-sided adhesive tapes, or in order to prevent the adhesive from sticking to the carrier in the case of single-sided adhesive tapes, the adhesive tapes, if not already present on a liner, can advantageously be or covered on both sides with a liner that is rolled up together with the adhesive tape. In addition to covering single- or double-sided adhesive tapes, liners are also used to cover pure adhesive compounds (adhesive transfer tape) and sections of adhesive tape (e.g. labels). These liners also ensure that the adhesive is not soiled before use.

Film former matrix

The adhesive tape according to the invention comprises a polymeric film-forming matrix in which the curable composition, which comprises at least one epoxy resin and at least one curing reagent for the epoxy resin, is contained. Such adhesive tapes thus comprise an adhesive film which is basically formed from a polymeric film-forming matrix (referred to as “film-forming matrix” for short in this document) with the curable composition embedded therein, which serves in particular as a reactive adhesive. The film-forming matrix forms a self-supporting three-dimensional film (the spatial expansion in the thickness direction of the film is usually much smaller than the spatial expansion in the longitudinal and transverse directions, i.e. than in the two spatial directions of the surface area of the film; of importance of the term “film”, see also below). In this film-forming matrix, the curable composition, in particular the reactive adhesive, is preferably essentially spatially evenly distributed (homogeneously), in particular so that the reactive adhesive - which might not be self-supporting without the matrix - has essentially the same (macroscopic) spatial distribution in the adhesive film according to the invention like the film-forming matrix.

The task of this matrix is to form an inert basic structure for the reactive monomers and / or reactive resins so that these are embedded in a film or a foil. This means that otherwise liquid systems can also be offered in film form. That way easier handling is guaranteed. The polymers on which the film-forming matrix is based are able to form a self-supporting film through sufficient interactions between the macromolecules, for example - without wishing to restrict the concept of the invention unnecessarily - through the formation of a network based on physical and / or chemical crosslinking .

Inert means in this context that the reactive monomers and / or reactive resins essentially do not react with the polymeric film-forming matrix under suitably selected conditions (for example at sufficiently low temperatures).

Suitable film-forming matrices for use in the present invention are preferably a thermoplastic homopolymer or a thermoplastic copolymer (collectively referred to as “polymers” in this document), or a blend of thermoplastic homopolymers or thermoplastic copolymers or one or more thermoplastic Homopolymers with one or more thermoplastic copolymers. In a preferred procedure, completely or partially semicrystalline thermoplastic polymers are used.

As thermoplastic polymers, for example polyesters, copolyesters, polyamides, copolyamides, polyacrylic acid esters, acrylic acid ester copolymers, polymethacrylic acid esters, methacrylic acid ester copolymers, thermoplastic polyurethanes and chemically or physically crosslinked substances of the aforementioned compounds can be chosen. The polymers mentioned can each be used as the only polymer used or as a component of a blend.

Furthermore, elastomers and - as representatives of the thermoplastic polymers already mentioned - thermoplastic elastomers alone or in a mixture as a polymeric film-forming matrix are conceivable. Thermoplastic elastomers, in particular semicrystalline, are preferred. The named - in particular thermoplastic - elastomers can each be used as the only polymer used or as a component of a blend, for example with further elastomers and / or thermoplastic elastomers and / or other thermoplastic polymers, such as those mentioned in the preceding paragraph.

Thermoplastic polymers with softening temperatures below 100 ° C. are particularly preferred. In this context, the term softening temperature stands for the temperature from which the thermoplastic granulate sticks to itself. If the component is If the polymeric film former matrix is a semicrystalline thermoplastic polymer, then it very preferably has a glass transition temperature of at most 25 ° C., preferably at most 0 ° C., in addition to its softening temperature (which is related to the melting of the crystallites).

In a preferred embodiment according to the invention, a thermoplastic polyurethane is used. The thermoplastic polyurethane preferably has a softening temperature of less than 100.degree. C., in particular less than 80.degree.

In a particularly preferred embodiment according to the invention, Desmomelt 530® is used as a polymeric film-forming matrix, which is commercially available from Bayer Material Science AG, 51358 Leverkusen, Germany. Desmomelt 530® is a hydroxyl-terminated, largely linear, thermoplastic, strongly crystallizing polyurethane elastomer.

For example, 5 to 80 parts by weight of at least the polymeric film-forming agent matrix can advantageously be used within a reactive adhesive film. According to the invention, the amount of the polymeric film-forming agent matrix within a reactive adhesive film is preferably in the range from about 15 to 60% by weight, preferably from about 30 to 50% by weight, based on the total amount of polymers of the polymeric film-forming matrix and reactive resins of the curable composition . Adhesives with particularly high bond strengths after curing are obtained when the proportion of the film-forming matrix is in the range from 15 to 25% by weight. Such adhesives, in particular with less than 20% film-forming matrix, are very soft and less dimensionally stable in the uncured state. The dimensional stability is improved if more than 20% by weight, in particular more than 30%, are used. Between 40 and 50% by weight pressure-sensitive adhesives are obtained which exhibit the best properties with regard to dimensional stability, but the maximum achievable bond strength drops. Very balanced adhesives with regard to dimensional stability and bond strength are obtained in the range from 30 to 40% by weight of film-forming matrix. The above% by weight figures are in each case based on the sum of the polymers and epoxy resins forming the film-forming matrix.

In a further very preferred procedure, non-thermoplastic elastomers are used as matrix polymers. The non-thermoplastic elastomers can in particular be a nitrile rubber or a mixture of several nitrile rubbers or act as a mixture of one or more other non-thermoplastic elastomers with one or more nitrile rubbers.

“Non-thermoplastic” in the context of the present specification is understood to mean those substances or compositions which, when heated to a temperature of 150 ° C, preferably when heated to a temperature of 200 ° C, very preferably when heated to a temperature of 250 ° C show no thermoplastic behavior, in particular in such a way that they are not considered thermoplastic in the thermoplasticity test (see experimental part).

The term "nitrile rubber" stands for "acrylonitrile butadiene rubber", the abbreviation NBR, derived from nitrile butadiene rubber, and denotes synthetic rubbers that are produced by copolymerizing acrylonitrile and butadiene in mass ratios of approximately 10:90 to 52:48 (acrylonitrile : Butadiene) can be obtained.

Nitrile rubbers are produced almost exclusively in an aqueous emulsion. In the prior art, the resulting emulsions are used as such (NBR latex) on the one hand or worked up to solid rubber on the other.

The properties of nitrile rubber depend on the ratio of the starting monomers and on its molar mass. Vulcanizates made from nitrile rubber have a high resistance to fuels, oils, fats and hydrocarbons and are distinguished from those made from natural rubber by their more favorable aging behavior, lower abrasion and reduced gas permeability.

Niril rubbers are available in a wide range. In addition to the acrylonitrile content, the different types are distinguished in particular on the basis of the viscosity of the rubber. This is usually indicated by the Mooney viscosity. This in turn is determined on the one hand by the number of chain branches in the polymer and on the other hand by the molar mass. In principle, a distinction is made between so-called cold and hot polymerization in polymerization. The cold polymerization is usually carried out at temperatures of 5 to 15 ° C. and, in contrast to the hot polymerization, which is usually carried out at 30 to 40 ° C., leads to a lower number of chain branches. Nitrile rubbers suitable according to the invention are available from a large number of manufacturers such as, for example, Nitriflex, Zeon, LG Chemicals and Lanxess.

Carboxylated nitrile rubber types are produced by the terpolymerization of acrylonitrile and butadiene with small amounts of acrylic acid and / or methacrylic acid in emulsion. They are characterized by high strength. The selective hydrogenation of the C = C double bond of nitrile rubber leads to hydrogenated nitrile rubbers (H-NBR) with improved resistance against temperature increases (up to 150 ° C in hot air or ozone) or swelling agents (e.g. sulfur-containing crude oils, brake or hydraulic fluids). Vulcanization takes place with common sulfur crosslinkers, peroxides or by means of high-energy radiation.

In addition to carboxylated or hydrogenated nitrile rubbers, there are also liquid nitrile rubbers. These are limited in their molar mass during the polymerization by the addition of polymerization regulators and are therefore obtained as liquid rubbers.

In order to improve the processability of rubbers, for example granulating granules from large rubber balls before further processing in mixers, inert separating aids such as talc, silicates (talc, clay, mica), zinc stearate and PVC powder are often added to the rubbers.

In one embodiment of the invention, the non-thermoplastic elastomers used are partially or exclusively those nitrile rubbers which have an acrylonitrile content of at least 25%, preferably at least 30%, very preferably at least 35%.

Hot-polymerized nitrile rubbers can be used excellently as matrix polymers. Such nitrile rubbers are highly branched and therefore have a particularly high tendency towards physical crosslinking and thus show particularly good shear strengths even in the uncured state.

Hardening reagent

As already stated above, the hardening reagent comprises all of the present accelerators and at least one hardener, with at least one copolymer according to the invention being present as accelerator.

Copolymers according to the invention usually do not have to be used in stoichiometric amounts, based on the functionality of the epoxy resin to be cured, in order to develop a good effect.

Typical amounts used are 15 to 35 parts by weight per 100 parts by weight of the epoxy resin (s) to be cured. If several copolymers according to the invention are used, the sum of the amounts used is advantageously in the abovementioned range.

In alternative embodiments, the amount used of the copolymers according to the invention is preferably in the range from 0.1 to 10 parts by weight, in particular from 0.5 to 5 parts by weight, preferably from 1 to 3 parts by weight, based in each case on 100 parts by weight . -Parts of the epoxy resin (s) to be cured - especially if the copolymer - for example in combination with Dicyandiamide, - are used. In some cases, amounts in the range of 4-8 parts by weight are advantageously used.

The compositions can also contain at least one further accelerator different from the copolymers of the present invention in the curing reagent. These are known to those skilled in the art of curable adhesives.

The curing reagent comprises - in addition to the copolymer (s) according to the invention - one or more hardeners for the epoxy resins and optionally one or more further accelerators for the curing reaction of the epoxy resins, these hardeners or accelerators not being copolymers according to the invention.

Compounds from the following list of dicyandiamide, anhydrides, epoxy-amine adducts, hydrazides and reaction products of diacids and multifunctional amines can particularly advantageously be selected as such additional hardeners or accelerators. Reaction products from diacids and multifunctional amines are, for example, reaction products from phthalic acid and diethylenetriamine.

In a very preferred embodiment of the invention, the curing reagent comprises dicyandiamide and one or more copolymer (s) according to the invention. Even more preferably, the curing reagent consists exclusively of dicyandiamide and one or more copolymers according to the invention. In combination with dicyandiamide, the at least one copolymer according to the invention takes on the effect of an accelerator, i.e. increases the reaction rate of the curing reaction of the epoxy resin compared to the situation in which dicyandiamide would be the only component of the curing reagent. The invention thus furthermore relates to an adhesive tape comprising at least one layer of a pressure-sensitive adhesive, the adhesive comprising a polymeric film-forming matrix and a curable composition, the curable composition comprising at least one epoxy resin and at least one curing reagent for the epoxy resin, and the curing reagent i) comprises or consists of at least one copolymer according to the invention and ii) dicyandiamide. Stoichimetric hardeners such as dicyandiamide are preferably used based on the amount of epoxy in the adhesive. To do this, the EEW of the epoxy mixture is first calculated using the following formula: where rriges = sum m, rrii masses of the individual components i of the mixture EEW, = epoxy equivalents of the components i

The amount of hardener m _H results from the amine equivalent of the hardener (AEW) and the EEWges of the epoxy mixture as follows: m _H = AEW * (mi / EEWges)

The copolymer (s) according to the invention acting as accelerator is / are then advantageously from 0.1 to 10 parts by weight, in particular from 0.5 to 5 parts by weight, preferably from 1 to 3 parts by weight Parts used, each based on 100 parts by weight of the epoxy resin to be cured. In some cases - especially when the copolymers according to the invention are a somewhat weaker accelerator - amounts in the range from 4 to 8 parts by weight are used.

If, in addition to the epoxy resins, other reactive resins are also present in the curable composition, further specific hardeners and / or accelerators can also be added to react with these components.

Epoxy resins

A single epoxy resin or a mixture of epoxy resins can be used as the epoxy resin (s) of the curable composition. In principle, epoxy resins which are liquid at room temperature or epoxy resins which are solid at room temperature or mixtures thereof can be used.

The one epoxy resin or at least one of the epoxy resins is preferably a solid; in particular one with a softening temperature of at least 45 ° C or one with a viscosity at 25 ° C of at least 20 Pa s, preferably 50 Pa s, in particular at least 150 Pa s (measured according to DIN 53019-1; 25 ° C, shear rate 1 xs ^_1 ). In a favorable embodiment of the adhesive tape according to the invention, the epoxy resins comprise a mixture of epoxy resins that are liquid at 25.degree. C. and that are solid at 25.degree. The proportion of the liquid epoxy resins in the epoxy hearts (E) is in particular from 10 to 90% by weight, more preferably from 20 to 75% by weight. The respective difference to 100% by weight of the epoxy resins is then given by solid epoxy resins. Adhesive tapes with such proportions of liquid and solid epoxy components show particularly balanced adhesive properties in the uncured state. If an adhesive tape with particularly good flow properties is desired, the proportion of liquid epoxy components is preferably 50 to 80% by weight. For applications in which the adhesive tapes have to bear a higher load even in the uncured state, a proportion of 15 to 45% by weight is particularly preferred. Such a resin or a mixture of different resins can be used.

The epoxy resins further preferably comprise at least two different epoxy resins (E-1) and (E-2), of which a. the first epoxy resin (E-1) has a dynamic viscosity of less than 500 Pa * s at 25 ° C., measured according to DIN 53019-1 at a measurement temperature of 25 ° C. and a shear rate of 1 × s ¹ , and b. of which the second epoxy resin (E-2) has a softening temperature of at least 45 ° C or at 25 ° C a dynamic viscosity of at least 1000 Pa * s, measured according to DIN 53019-1 at a measuring temperature of 25 ° C and a shear rate of 1 xs ¹ , where in particular the proportion of the first epoxy resin (E-1) 10 to 90% by weight, preferably 20 to 75% by weight and the proportion of the second epoxy resin (E-2) 10 to 90% by weight, is preferably 25 to 80 wt .-%, based on the total of epoxy resins. The epoxy resin component advantageously consists of these two epoxy resins (E-1) and (E-2), so that the proportion of the two epoxy resins (E-1) and (E-2) in the total epoxy resin is 100% by weight add. Particularly good pressure-sensitive adhesives are obtained when the proportion of epoxy resin (E2) is in the range from 40 to 80% by weight, in particular from 60 to 75% by weight. In a special embodiment, the proportion of epoxy resins (E-2) which have a softening temperature of at least 45 ° C. is at least 35% by weight, in particular in the range from 40 to 70% by weight.

The cohesion of the uncrosslinked pressure-sensitive adhesives while still having sufficient pressure-sensitive adhesiveness is particularly good if the proportion of epoxy resins with a softening temperature of at least 45 ° C. is at least 15% by weight, in particular in the range from 20% by weight to 75% by weight is based on the total epoxy resin. The flow behavior is improved if it contains less than 55% by weight, in particular between 25% by weight and 45% by weight.

Epoxy resins to be used advantageously as epoxy resin or as part of the totality of epoxy resins are, for example, elastomer-modified epoxy resins, silane-modified epoxy resins or fatty acid-modified epoxy resins.

As elastomer-modified epoxy resins for the purposes of the present invention are - in particular liquid, usually highly viscous - epoxy resins with an average functionality of at least two and an elastomer content of up to 50 wt .-%, preferably with such a functionality of 5 - 40 wt .-% , to understand. The epoxy groups can be terminal and / or arranged in the side chain of the molecule. The elastomeric structural component of these flexibilized epoxy resins consists of polyenes, diene copolymers and polyurethanes, preferably of polybutadiene, butadiene-styrene or butadiene-acrylonitrile copolymers.

An epoxy resin modified by butadiene-acrylonitrile copolymers (nitrile rubber) is, for example, an epoxy prepolymer which is obtained by modifying an epoxy resin with at least two epoxy groups in the molecules with a nitrile rubber. A reaction product of glycerol or propylene glycol and a halogen-containing epoxy compound, such as epichlorohydrin, or the reaction product of a polyhydric phenol, such as hydroquinone, bisphenol-A, and a halogen-containing epoxide is advantageously used as the epoxy base. A reaction product of a bisphenol A type epoxy resin having two terminal epoxy groups is desirable.

To bind the epoxy resins, in the case of butadiene polymers or butadiene-acrylonitrile copolymers (so-called nitrile rubbers), a third monomer with an acid function - for example acrylic acid - can also be polymerized.

So-called carboxy-terminated nitrile rubbers (CTBN) are obtained from the acid and the nitrile rubbers. As a rule, these compounds contain acid groups not only at the ends, but also along the main chain. CTBN are offered, for example, under the trade name Hycar from B. F. Goodrich. These have molecular weights between 2000 and 5000 and acrylonitrile contents between 10% and 30%. Specific examples are Hycar CTBN 1300 x 8, 1300 x 13 or 1300 x 15.

The reaction with butadiene polymers proceeds accordingly. By reacting epoxy resins with CTBN, so-called epoxy-terminated nitrile rubbers (ETBN) are obtained, which are used with particular preference for this invention. Such ETBNs are commercially available, for example, from Emerald Materials under the name HYPRO ETBN (previously Hycar ETBN) - such as Hypro 1300X40 ETBN, Hypro 1300X63 ETBN and Hypro 1300X68 ETBN.

An example of an epoxy-terminated butadiene rubber is Hypro 2000X174 ETB.

Further examples of elastomer-modified epoxy-functional compounds are a reaction product of a diglycidyl ether of neopentyl alcohol and a butadiene / acrylonitrile elastomer with carboxyl ends (e.g. EPONTM Resin 58034 from Resolution Performance Products LLC), a reaction product of a diglycidyl ether of bisphenol A and a butadiene / acrylonitrile elastomer with carboxyl ends (e.g. EPON ™ Resin 58006 from Resolution Performance Products LLC), a butadiene / acrylonitrile elastomer with carboxyl ends (e.g. CTBN-1300X8 and CTBN-1300X13 from Noveon , Inc., Cleveland, Ohio) and an amine-terminated butadiene / acrylonitrile elastomer (e.g., ATBN-1300X16 and ATBN-1300X42 from Noveon, Inc.). An example of the elastomer-modified epoxy resin adduct is the reaction product of an epoxy resin based on bisphenol F and a butadiene / acrylonitrile elastomer with carboxyl ends (e.g. EPON ™ Resin 58003 from Resolution Performance Products LLC).

The proportion of elastomer-modified epoxy resins based on the total amount of epoxy resins in the curable composition can be between 0 and 100%. For bonds with particularly high bond strengths and low elongation, rather lower proportions - such as, for example, 0 to 15% by weight - are chosen. In contrast to this, adhesives with high elongation values are obtained if the proportion is greater than 40% by weight, in particular greater than 60% by weight. For many applications, a balanced relationship between bond strength and elongation is desired. Here proportions between 20 to 60% by weight, in particular 30 to 50% by weight, are preferred. Depending on the requirement profile, it can also be advantageous to use adhesives with a proportion of up to 100%.

Silane-modified epoxy resins can be used very advantageously as further suitable representatives for the epoxy resins. A single silane-modified epoxy resin or two, three or even more silane-modified epoxy resins can be present in the curable composition. The curable composition can be limited to the silane-modifiable epoxy resin (s) as curable reactive resins. In addition to the epoxy resin (s), other epoxy resins can also be present, which not silane-modified - for example elastomer-modified, in particular nitrile rubber-modified - epoxy resins and / or fatty acid-modified epoxy resins, as detailed in detail in this document - and / or reactive resins that are not epoxy resins.

If a single silane-modified epoxy resin is present, this can in particular be selected from the silane-modified epoxy resins described below as being preferred. If several silane-modified epoxy resins are present, at least one of the epoxy resins is advantageously one of the compounds described below as preferred silane-modified epoxy resins. Further preferred are all silane-modified epoxy resins such as are described below as being preferred.

The chemical modification of epoxy resins can be used to control the properties of adhesives. Modified epoxy resins according to the invention are selected in particular from silane-modified epoxy resins. Silane group-modified epoxy resins are epoxy resins to which one or more silane groups are chemically bonded.

In principle, there are different ways of chemically bonding silane groups to epoxy resins.

In a preferred procedure, the epoxy resin used is a silane-modified epoxy resin that is obtainable by dealcoholization condensation reaction between a bisphenol epoxy resin and a hydrolyzable alkoxysilane. Such epoxy resins are described, for example, in EP 1114834 A, the disclosure content of which is intended to be incorporated into the present document by reference.

The bisphenol epoxy resin can advantageously be selected in such a way that it has an epoxy equivalent weight of more than 180 g / eq, and preferably of less than 5000 g / eq. The epoxy equivalent weight (abbreviation EEW) is a characteristic and important parameter for epoxy resins or epoxy crosslinkers. According to DIN EN ISO 3001: 1999-11, the epoxy equivalent weight indicates the solid content of the substance in question in grams per epoxy group. It is preferred to use epoxy resins with an EEW> 180 g / eq, since otherwise there may not be sufficient hydroxyl groups for the condensation reaction with the alkoxysilanes.

The bisphenol-epoxy resin for reaction with the hydrolyzable alkoxysilane is preferably a compound corresponding to the following formula used. As a rule, this is a mixture of corresponding compounds of the above bisphenol-epoxy resin formula with a varying number of repetitions m of the unit in square brackets. The bisphenol-epoxy resin is selected in particular in such a way that the average is from m 0.07 to 16.4, i.e. the number-average molar masses are between approximately 350 g / mol and 4750 g / mol.

In a further preferred manner, the hydrolyzable alkoxysilane is either a compound corresponding to the general formula

R ^x _p Si (OR ^Y ) ₄ -p where p is 0 or 1, R ^{x is} a CC alkyl group, an aryl group or an unsaturated aliphatic hydrocarbon group which can have a functional group bonded directly to a carbon atom, R ^{Y is} a hydrogen atom or represents a lower alkyl group, and the radicals R ^{Y can be} identical or different, or the hydrolyzable alkoxysilane is a partial condensate of the compound mentioned. The functional group directly bonded to a carbon atom may be, for example, vinyl group, mercapto group, epoxy group, glycidoxy group, and so on. The lower alkyl group may, for example, be a straight or branched alkyl group having 6 or fewer carbon atoms.

Examples of the hydrolyzable alkoxysilane include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabuthoxysilane and the like tetraalkoxysilanes; Methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, Methyltributhoxysilan, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-Mercaptopropyltrimethoxy- silane, 3-mercaptopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3,4-epoxyclohexylethyltrimethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane and like trialkoxysilanes; or partial condensates of these compounds.

Among these compounds, tetramethoxysilane, tetraethoxysilane and like tetraalkoxysilanes or partial condensates thereof are preferred. It is particularly preferred Poly (tetramethoxysilane) which is a partial condensate of tetramethoxysilane represented by the formula

(where the average of n is 1 to 7). The poly (tetramethoxysilane) represented by the above formula may contain a molecule in which n is 0 so long as the average of n is 1 or more. The number average molecular weight of the poly (tetramethoxysilane) is preferably from about 260 to about 1200. In addition, unlike tetramethoxysilane, poly (tetramethoxysilane) is not toxic.

In a further preferred procedure, the epoxy resin used is such a silane-modified epoxy resin which can be obtained by modifying bisphenol diglycidyl ether with alkoxysilanes which carry an epoxy group. Such silane-modified epoxides and their production method are described in US Pat. No. 8,835,574 A, the disclosure content of which is also incorporated into this document by reference. In the process described there, the epoxyalkoxysilane is first partially hydrolyzed and partially condensed in the presence of water. In a second step, a bisphenol diglycidyl ether is added and bound to the siloxane partial condensate.

In a further synthesis route of silane-modified epoxy resins which can advantageously be used according to the invention, alkoxysilanes which contain an isocyanate group are bound to the aliphatic hydroxyl groups with the formation of a urethane group.

The proportion of silane-modified epoxy resins based on the total amount of epoxy resins in the curable composition can be between 0 and 100%. In order to reduce the drawing on of certain siliconized liners, lower proportions - such as 5 to 25% - are chosen. For a balanced performance even after moist and warm storage, proportions between 10 to 50% by weight, in particular 20 to 40% by weight, have proven to be outstanding.

According to the invention, fatty acid-modified epoxides can also be used very advantageously as epoxy resins. Epoxy resin esters, also referred to as epoxy esters, are preferably used as fatty acid-modified epoxy resins, that is to say the esterification products of epoxy resins with saturated or unsaturated fatty acids.

A single fatty acid-modified epoxy resin or two, three or even more fatty acid-modified epoxy resins can be present in the curable composition. The curable composition can be limited to the fatty acid-modifiable epoxy resin or resins as curable reactive resins. In addition to the fatty acid-modified epoxy resin (s), other epoxy resins that are not fatty acid-modified - for example elastomer-modified, in particular nitrile rubber-modified - epoxy resins and / or silane-modified epoxy resins, as detailed in this document - and / or reactive resins that do not Are epoxy resins.

If a single fatty acid-modified epoxy resin is present, this can in particular be selected from the fatty acid-modified epoxy resins described below as preferred. If several fatty acid-modified epoxy resins are present, at least one of the epoxy resins is advantageously one of the compounds described below as preferred fatty acid-modified epoxy resins. All fatty acid-modified epoxy resins are more preferably those as described below as being preferred.

The chemical modification of epoxy resins can be used to control the properties of adhesives. Modified epoxy resins according to the invention are selected in particular from fatty acid-modified epoxy resins. Fatty acid group-modified epoxy resins are those epoxy resins to which one or more fatty acids are chemically bonded, in particular through esterification reactions.

Epoxy resins of the bisphenol A / epichlorohydrin type in accordance with the general formula already introduced above can be used as the epoxy resin base for the fatty acid-modified epoxy resins, in particular epoxy esters serve. As the basis for the fatty acid-modified epoxides, the bisphenol-epoxy resin of the above formula is chosen in particular such that the average is from m = 0.07 to 16.4, the number-average molar masses are between about 350 g / mol and 4750 g / mol. Compounds of formula 1 with m = 2.3 to m = 10 are particularly preferably used in pure form (with integer values for m) or in the form of mixtures (corresponding to number average molar masses between about 1000 and about 3000 g / mol).

Both the terminal epoxy groups and the secondary hydroxyl groups of bisphenol-based epoxy resins can react with fatty acids. During the esterification, the two epoxy rings are usually opened first, then the hydroxyl groups react.

Each epoxy group is equivalent to 2 hydroxyl groups, since a ß-hydroxy ester is formed after the reaction of an acid group with an epoxide. These ß-hydroxy groups can also react with fatty acids. The production is typically carried out at temperatures of 240-260 ° C. under a protective gas atmosphere, preferably under azeotropic conditions, in order to remove the water of reaction that is released. The reaction is optionally accelerated by adding catalysts such as calcium or zinc soaps, for example fatty acids such as stearic acid. Depending on the desired property, 40 to 80% of the available functional groups of the epoxy resin are converted with fatty acids.

An epoxy resin of type n (corresponds to the number of free OH groups along the chain) can theoretically bind a maximum of n + 4 fatty acid molecules per epoxy resin molecule (degree of esterification 100%). Accordingly, the “oil length” for epoxy resin esters is defined as follows: short oil: degree of esterification 30-50%; medium oil: degree of esterification 50-70%; long oil: degree of esterification 70-90%.

As fatty acids for the esterification, for example coconut oil fatty acid, ricineal fatty acid (fatty acid of dehydrated castor oil), linseed oil fatty acid, soybean oil fatty acid or tall oil fatty acid are well suited according to the invention.

Further fatty acids advantageous according to the invention are α-linolenic acid, stearidonic acid, eicosapentaenoic acid, docosahexaenoic acid, linoleic acid, g-linolenic acid, dihomogammlinolenic acid, arachidonic acid, docosa-7,10,13,16-tetrain-1 acid, palmitoleic acid, vaccenic acid, Oleic acid, elaidic acid, gadoleic acid, 13-eicosenoic acid, erucic acid, nervonic acid, stearic acid, Mead ^'s acid.

Dimers and oligomers of unsaturated fatty acids can also be used, for example the dimers of tall oil fatty acids.

The proportion of fatty acid-modified epoxy resins based on the total amount of epoxy resins in the curable composition can be between 0 and 100%. For bonds with particularly high bond strengths even at high temperatures, rather lower proportions - such as, for example, 5 to 25% by weight - are chosen. For a good performance even after moist and warm storage, proportions between 10 to 50% by weight, in particular 20 to 40% by weight, have proven to be outstanding.

Manufacturing process

The adhesives used according to the invention can in principle be prepared by the processes known to the person skilled in the art.

A very gentle process with which even difficult to process raw materials such as non-thermoplastic elastomers - for example nitrile rubbers - can be processed is extrusion, in particular using a planetary roller extruder. This even enables the incorporation of the sensitive components of the curable composition, such as reactive resins and hardeners, without these components reacting in advance or causing other problems in the process. Such a preliminary reaction would already cure or at least partially cure the adhesive tape and would run counter to the goal of a storable, transportable adhesive tape which is only intended to be cured after application.

Planetary roller extruders as a continuously operating unit have been known for a long time and were first used in the processing of thermoplastics such as PVC, where they were mainly used to feed the downstream units such as calenders or rolling mills. Due to their advantage of the large surface renewal for material and heat exchange, with which the energy introduced via friction can be dissipated quickly and effectively, as well as the short dwell time and the narrow dwell time spectrum, their field of application has recently expanded to include compounding processes, among other things require temperature-controlled driving style. Planetary roller extruders consist of several parts, namely a rotating central spindle, a housing surrounding the central spindle at a distance with internal teeth and planetary spindles, which in the cavity between the central spindle and the internally toothed housing rotate like planets around the central spindle. Insofar as internal toothing of the housing is mentioned in the following, this also includes a multi-part housing with a bushing, which forms the internal toothing of the housing. In the planetary roller extruder, the planetary spindles mesh with both the central spindle and the internally toothed housing. At the same time, the planetary spindles slide with the end pointing in the conveying direction on a stop ring. The planetary roller extruders have an extremely good mixing effect compared to all other types of extruder, but a much lower conveying effect.

Planetary roller extruders are available in different designs and sizes, depending on the manufacturer. Depending on the desired throughput, the diameter of the roller cylinders is typically between 70 mm and 400 mm.

Planetary roller extruders usually have a filling part and a compounding part.

The filling part, usually corresponding to a filling zone, consists of a screw conveyor to which all solid components - present in particular the non-thermoplastic elastomers and possibly other components - are continuously metered. The screw conveyor then transfers the material to the compounding section. The area of the filling part with the screw is preferably cooled in order to avoid caking of materials on the screw. However, there are also embodiments without a screw part, in which the material is fed directly between the central and planetary spindles. However, this is not important for the effectiveness of the method according to the invention. The central spindle can also preferably be cooled.

The compounding part usually consists of a driven central spindle and several planetary spindles which rotate around the central spindle within a roller cylinder with internal helical teeth. The speed of the central spindle and thus the speed of rotation of the planetary spindles can be varied and is therefore an important parameter for controlling the compounding process. The compounding part can be made up of a single compounding cell or a sequence of several - in particular with stop rings and optionally additional injection or dispersing rings - separate compounding zones are formed. The number and arrangement of the planetary spindles can vary from compounding zone to compounding zone. Typically, the compounding part will preferably consist of at least two, but particularly preferably three or four coupled roller cylinders, each roller cylinder being able to have one or more separate temperature control circuits.

The surrounding housing has a contemporary design with a double jacket. The inner jacket is formed by a bushing that is provided with internal teeth. The important cooling of the planetary roller extruder is provided between the inner and outer jacket.

The planetary spindles do not require any guidance in the circumferential direction. The toothing ensures that the distance between the planetary spindles remains the same in the circumferential direction. It can be said that it is self-guided

The materials are circulated between central and planetary spindles or between planetary spindles and the helical gearing of the roller part, so that the materials are dispersed to form a homogeneous compound under the influence of shear energy and external temperature control.

The number of planetary spindles rotating in each roller cylinder can be varied and thus adapted to the requirements of the process. The number of spindles influences the free volume within the planetary roller extruder, the dwell time of the material in the process and also determines the area size for the heat and material exchange. The number of planetary spindles has an influence on the compounding result via the shear energy introduced. With a constant roller cylinder diameter, a greater number of spindles can achieve better homogenizing and dispersing performance or a greater product throughput. To achieve a good ratio of compounding quality to product rate, preferably at least half or even at least 3/4 of the possible number of planetary spindles should be used.

The maximum number of planetary spindles that can be installed between the central spindle and the roller cylinder depends on the diameter of the roller cylinder and the diameter of the planetary spindles used. When using larger roller diameters, as are necessary to achieve throughput rates on a production scale, or smaller diameters for the planetary spindles, the roller cylinders can be equipped with a larger number of planetary spindles. Typically, with a roll diameter of D = 70 mm up to seven planetary spindles are used, while with a roller diameter of D = 200 mm, for example, ten and with a roller diameter of D = 400 mm, for example, 24 planetary spindles can be used.

Of course, each roller cylinder can be equipped differently with regard to the number and type of planetary spindles and thus be adapted to the respective formulation and process requirements.

According to the invention, it has been possible to provide storage-stable, curable compositions based on epoxy which are outstandingly suitable for use as adhesives in adhesive tapes and with which it is possible to produce even very thick adhesive tapes. The products produced have very good adhesion, in particular to glass surfaces. The selected components have made it possible to reduce the solubility of the hardeners used in the other components or to avoid it altogether, resulting in products that are very stable in storage, which are easy to transport and store and also when used by the customer - even after a long storage period. ensure their full bonding performance.

The curing of the adhesives or adhesive tapes according to the invention after application can advantageously take place at temperatures between 120 ° C. and 200 ° C. for 10 to 120 minutes. The exact conditions depend on the hardener used and the accelerator used, if any, and the amount of accelerator used. Typically, accelerators between 0.5 phr and 5 phr are used, phr referring to the amount of epoxy resins used. Exemplary curing conditions are 30 minutes at 180 ° C, 30 minutes at 160 ° C, 35 minutes at 145 ° C, 60 minutes at 130 ° C, 120 minutes at 120 ° C.

According to the invention, very thick adhesive tapes can be produced. The administration of adhesives of high viscosity per se in the form of stable films - for example by embedding the reactive adhesive in a polymeric film-forming matrix - opens up, with the adhesives of the invention, access to very storage-stable adhesive films in a wide variety of dimensions.

It is possible to use adhesive films in a very thin form - for example from a few μm thick - over conventional adhesive tape thicknesses, for example with adhesive layers from 25 μm to 100 μm thick - such as about 50 μm thick adhesive layers - up to adhesive tapes with very thick adhesive layers of over 100 μm, preferably over 200 μm, even 300 μm or more, 500 mm or more, 1 mm or more up to layers of adhesive in the range of a few millimeters and even Centimeters, both as single-layer adhesive films (transfer adhesive tapes) and as single- or double-sided adhesive multi-layer adhesive tapes, in particular also with a carrier material.

Reference methods

The respective parameter data in the context of this document relate to the following reference determination methods, unless otherwise specified or indicated in detail.

viscosity

Dynamic viscosity is a measure of the flowability of the fluid coating material. The dynamic viscosity is determined according to DIN 53019. A viscosity of less than 108 Pa s is referred to as a fluid. The viscosity is measured in a cylinder rotation viscometer with a standard geometry according to DIN 53019-1 at a measuring temperature of 23 ° C. and a shear rate of 1 s-1.

molar mass

Information on the number-average molar mass Mn or the weight-average molar mass Mw refer to the measurement by means of gel permeation chromatography (GPC) as follows:

THF (tetrahydrofuran) with 0.1% by volume of trifluoroacetic acid was used as the eluent. The measurement was carried out at 25 ° C. PSS-SDV, 5 m, 10 ³ Å, ID 8.0 mm x 50 mm was used as the guard column. The columns PSS-SDV, 5 m, 10 ³ and 105 and 106, each with an ID of 8.0 mm × 300 mm, were used for the separation. The sample concentration was 4 g / l, the flow rate 1.0 ml per minute. It was measured against polystyrene standards.

Softening temperatures of polymers or resins

Unless otherwise specified, the softening temperature is carried out according to the relevant method known as "Ring and Ball" and standardized according to ASTM E28.

An HRB 754 ring-ball machine from Herzog is used to determine the softening temperature. The samples to be measured - such as the resin or the elastomer - are first finely ground in a mortar. The resulting powder is filled into a brass cylinder with a bottom opening (inner diameter at the upper part of the cylinder 20 mm, diameter of the bottom opening of the cylinder 16 mm, height of the cylinder 6 mm) and placed on a heating table melted. The filling quantity is chosen so that the sample completely fills the cylinder without protrusion after melting.

The resulting test specimen, including the cylinder, is placed in the test holder of the HRB 754. Glycerine is used to fill the bath if the softening temperature is between 50 ° C and 150 ° C. A water bath can also be used at lower softening temperatures. The test balls have a diameter of 9.5 mm and weigh 3.5 g. According to the HRB 754 procedure, the ball is placed above the test specimen in the temperature bath and placed on the test specimen. There is a collecting plate 25 mm below the cylinder base, and a light barrier 2 mm above it. During the measurement process, the temperature is increased at 5 ° C / min. In the temperature range of the softening temperature, the ball begins to move through the bottom opening of the cylinder until it finally comes to a stop on the collecting plate. In this position it is detected by the light barrier and the temperature of the bath is registered at this point in time. There is a double determination. The softening temperature is the mean value from the two individual measurements.

Static glass transition temperature

The static glass transition temperature (Tg) is determined using dynamic differential calorimetry in accordance with DIN 53765: 1994-03. For this purpose, approximately 7 mg of the sample are weighed exactly into an aluminum pan and then introduced into the measuring device (device: DSC 204 F1, Netzsch). An empty crucible is used as a reference. Two heating curves are then recorded with a heating rate of 10 K / min. The information on the glass transition temperature Tg relates to the glass transition temperature Tg according to DIN 53765: 1994-03 of the second heating curve, unless otherwise stated in the individual case.

Further reference methods result from the test methods in the experimental part.

Experimental part

Shelf life

The shelf life (Lf) of the (uncured) copolymers was determined by DSC. For this purpose, the heat of reaction of a fresh mixture of Epikote828LVEL with 7.03% dicyandiamide (Dyhard 100SF) and, unless otherwise noted, 5phr of the copolymer to be tested is determined (AH _f nsc _h ) and the residual heat of reaction after storage for 10d at 60 ° C ( DHKMQO) compared.

Lf = DHΐ (M60 / ÄHfnsch

The shelf life within the meaning of the invention is fulfilled when Lf is> 85%, in particular> 95%, and is referred to in the experiments as “passed”.

Tpeak

The _{temperature of the curing curve} , determined by DSC, from the shelf life measurement, which is reached at the maximum of the exothermic reaction signal, is referred to as Tpeak.

Used raw materials:

List of the monomers used to prepare the exemplary polymers a) High-Tg monomers

“TUEMA” 2- (3-toloidylureido) ethyl methacrylate (homopolymer-Tg ~ 137 ° C)

“PhMal” n-phenyl maleimide (homopolymer Tg ~ 325 ° C)

“MMA” methyl methacrylate (homopolymer Tg ~ 105 ° C)

“S” styrene (homopolymer Tg ~ 100 ° C) b) Monomers with tertiary aromatic amine groups

“VI m” vinylimidazole (homopolymer Tg ~ 131 ° C)

“ImEMA” imidazole ethyl methacrylate (homopolymer Tg ~ 60 ° C)

“ImEUr-M” imidazole ethyl urethane methacrylate (homopolymer Tg ~ 32 ° C)

“2M-lmEMA” 2-methylimidazole ethyl methacrylate (homopolymer Tg ~ 76 ° C)

“DMAP-M” N-methyl-N- (4-pyridyl) amino) ethyl methacrylate) (homopolymer Tg ~ 29 ° C) PMI (TCI Chemicals, no purification before use), MMA (Sigma Aldrich, distilled before use), S (Merck, distilled before use) and Vlm (Sigma-Aldrich, no purification before use).

Production of the non-commercial monomers p-toluidine urea ethyl methacrylate

0.760 g (7.09 mmol) of p-toluidine and 0.0365 g (0.325 mmol) of 1,4-diazabicyclo [2.2.2] octane in 10 ml of tetrahydrofuran were placed in a two-necked flask under a nitrogen atmosphere. 1.00 ml (7.08 mmol) of 2-isocyanatoethyl methacrylate were added dropwise to the solution. The reaction mixture was then stirred at 60 ° C. for 3 h and the solvent was removed under reduced pressure. The resulting crude product was dissolved in DCM, washed once with water and twice with saturated sodium chloride solution, the solution was dried with magnesium sulfate, and then the solvent was removed under reduced pressure. Purification by column chromatography (silica gel; nH: EA 2: 1 to 1: 1) gave 1.60 g (6.10 mmol; 86%) of a beige solid.

Imidazole ethyl methacrylate (ImEMA) In a two-necked flask with a reflux condenser, 8.01 g (0.118 mol) of imidazole and 16.0 g of ethylene carbonate (0.182 mol) were dissolved in 30 ml of toluene and heated under reflux for 6 h. After cooling to room temperature, the toluene phase was removed and 11 ml of concentrated hydrochloric acid were added while cooling in a water bath. The solution was washed three times with DCM and the aqueous phase was adjusted to pH 12 by adding potassium carbonate. The aqueous phase was extracted with dichloromethane and the resulting solution was dried with magnesium sulfate, and then the solvent was removed under reduced pressure. 6.14 g (0.0548 mol; 47%) of the product were obtained in the form of a brown, oily liquid. In a two-necked flask under a nitrogen atmosphere, a solution of 1.92 g (17.1 mmol) of hydroxyethylimidazole, 2.80 ml of triethylamine (20.2 mmol) and 10 mg of phenothiazine in 8 ml of THF was added to a solution of 2.00 ml in an ice bath (20.5 mmol) methacryloyl chloride in 4 ml THF was slowly added dropwise. The solution was allowed to warm to room temperature overnight and the solid formed was then filtered off. The solvent was then removed under reduced pressure. Purification by column chromatography (silica gel) with DCM: MeOH 100: 3 gave 2.15 g (11.9 mmol; 70%) of a yellowish liquid. 2-methylimidazole ethyl methacrylate (2M-lmEMA) In a two-necked flask with a reflux condenser, 5.00 g (0.0609 mol) of 2-methylimidazole and 8.34 g of ethylene carbonate (0.0947 mol) were dissolved in 20 ml of toluene and heated under reflux for 5 hours 30 minutes. After cooling to room temperature, the toluene phase was removed and 11 ml of concentrated hydrochloric acid were added while cooling in a water bath. The solution was washed three times with DCM and the aqueous phase was adjusted to pH 12 by adding potassium carbonate. The aqueous phase was extracted with dichloromethane and the resulting solution was dried with magnesium sulfate, and then the solvent was removed under reduced pressure. 4.58 g (0.0363 mol; 60%) of the product were obtained in the form of a brown, oily liquid. In a two-necked flask under a nitrogen atmosphere, a solution of 3.21 g (25.4 mmol) of PR040, 4.30 ml of triethylamine (31.0 mmol) and 10 mg of phenothiazine in 13 ml of THF was added to a solution of 3.03 ml in an ice bath (31.0 mmol) methacryloyl chloride in 7 ml THF was slowly added dropwise. The solution was allowed to warm to room temperature overnight and the solid formed was then filtered off. The solvent was then removed under reduced pressure. After purification by column chromatography (silica gel) with DCM: MeOH 100: 3, 1.25 g (6.04 mmol; 24%) of a yellowish liquid were obtained. Methylaminopyridine ethyl methacrylate (DMAP-M)

In a two-necked flask under a nitrogen atmosphere, 7.51 g (50.1 mmol) of 4-chloropyridine hydrochloride were dissolved in 50.0 ml (622 mmol) of 2-methylaminoethanol and the mixture was stirred at 120 ° C. for 14 h. The 2-methylaminoethanol was then distilled off and the residue that remained was dissolved in ethyl acetate and washed three times with saturated sodium chloride solution. Sodium hydroxide was added to the collected aqueous phases and these were extracted three times with ethyl acetate. The collected organic phases were dried with magnesium sulfate, the solvent was removed under reduced pressure and the crude product was purified by means of column chromatography (silica gel, DCM: MeOH 10: 1 to 10: 2). 5.14 g (33.6 mmol; 67%) of a yellow crystalline solid were obtained

In a two-necked flask under a nitrogen atmosphere, a solution of 1.54 ml was added to a solution of 2.01 g (13.2 mmol) of PR065, 2.20 ml of triethylamine (15.9 mmol) and 10 mg of phenothiazine in 15 ml of THF in an ice bath (15.8 mmol) methacryloyl chloride in 10 ml THF was slowly added dropwise. The solution was allowed to warm to room temperature overnight and the solid formed was then filtered off. The solvent was then removed under reduced pressure. Purification by column chromatography (silica gel; DCM: MeOH 10: 1) gave 1.62 g (7.35 mmol; 55%) of a yellowish liquid.

Imidazole ethyl urethane methacrylate (ImEUr-M)

In a two-necked flask with a reflux condenser, 8.01 g (0.118 mol) of imidazole and 16.0 g of ethylene carbonate (0.182 mol) were dissolved in 30 ml of toluene and heated under reflux for 6 h. After cooling to room temperature, the toluene phase was removed and 11 ml of concentrated hydrochloric acid were added while cooling in a water bath. The solution was washed three times with DCM and the aqueous phase was adjusted to pH 12 by adding potassium carbonate. The aqueous phase was extracted with dichloromethane and the solution obtained was dried with magnesium sulfate and then the solvent is removed under reduced pressure. 6.14 g (0.0548 mol; 47%) of the product were obtained in the form of a brown, oily liquid.

2) 1.59 g (14.2 mmol) of hydroxethylimidazole and 0.0801 g (0.714 mmol) of 1,4-diazabicyclo [2.2.2] octane in 30 ml of tetrahydrofuran were placed in a two-necked flask under a nitrogen atmosphere. 2 ml (14.2 mmol) of 2-isocyanatoethyl methacrylate were added dropwise to the solution. The reaction mixture was then stirred at 65 ° C. for 6 h and the solvent was removed under reduced pressure. After purification by column chromatography (silica gel) DCM: MeOH 100: 1 to 100: 5), 2.89 g (11.1 mmol; 86%) of a beige solid were obtained.

Polymerizations

General instruction: The respective monomer compositions, 5 mol% AIBN and regulator (mercaptoethanol, if used) were dissolved in DMF (30% strength solution) and the solutions were each flushed for 3 min with argon. The polymerization was then carried out for 22 h at 65 ° C. in an oil bath. Polymers obtained were precipitated in diethyl ether and dried under reduced pressure at 60 ° C.

List of exemplary polymers

Table 1

Table 1 shows the Tpeak temperatures of the respective polymers and indicates whether the storage test was passed or not.

The activating effect of the nitrogen-containing aromatic heterocyclic group is surprisingly particularly effective when it is not bound directly to the polymer backbone. This becomes clear when comparing B1 and B2. Both accelerators are storage-stable and show an accelerating effect. However, the peak temperature of B2 is 10 ° C lower. Without being tied to a theory, it is assumed that decoupling from the polymer backbone by at least 2, preferably 4 atoms results in the amino groups being more accessible to the reactive resin when the Tg is exceeded.

B4-B7 are examples according to the invention with different amounts of monomers B in the polymer (20% -60%). The examples can be stored and show strong activating properties (B4-B6 Tp _e ak = 152/153 ° C, B7 T _Pe ak = 167 ° C). The activating property of B7 with only 20% monomer B initially appears to be weaker. However, the same amount of accelerator (5phr) was used in the DSC experiment. Because of the lower amount in the copolymer, there are fewer accelerating groups in the curing test. This can be counteracted by simply increasing the amount of accelerator. Surprisingly, the activating effect does not increase with an increasing amount of monomer B, as can be clearly seen in the range according to the invention between 45% and 60% (B4-B6), as well as in the counterexample V1, which consists of 100% ImEMA. Without being tied to a theory, it is assumed that if the ImEMA proportions are too high, the solubility that is introduced via the high Tg monomers (monomers A) is greatly reduced, so that the accelerating monomers B are not sufficiently effective Form are available. Accelerator polymers according to the invention can also be obtained with commercially available high-Tg monomers such as MMA and n-phenylmalimide. This is shown with B8 and B9. Imidazoles have proven to be particularly reactive and at the same time easy to store (B2 unsubstituted imidazole, B10 methylimidazole). But other tertiary aromatic amino groups also have an accelerating effect and can still be used for very storable epoxy resin adhesives. This is shown by way of example in B11 with a tertiary aromatic amine comparable to DMAP.

Use in reactive pressure-sensitive adhesive

Raw materials used

Breon N41 H80 Hot-polymerized nitrile-butadiene rubber with an acrylonitrile content of 41% by weight from Zeon Chemicals (London, UK). Mooney viscosity according to technical data sheet 70 - 95.

PolyDis PD3611 nitrile rubber modified epoxy resin based on bisphenol F diglycidyl ether with an elastomer content of 40% by weight and a weight per epoxy of 550 g / eq from Schill + Seilacher "Struktol". Viscosity at 25 ° C of 10000 Pa s.

PolyDis PD3691 Nitrile rubber modified epoxy resin based on

Bisphenol A diglycidyl ether with an elastomer content of 5% by weight and a weight per epoxide of 205 g / eq from Schill + Seilacher “Struktol”. Viscosity at 25 ° C of 300 Pa s.

Dyhard 100S Latent hardener from AlzChem for epoxy systems consisting of micronized dicyandiamide in which 98% of the particles are smaller than 10 μm.

Dyhard UR500 Latent accelerator based on dimethyl urea for epoxy systems in which 98% of the particles are smaller than 10 pm. Adhesives

Mass composition K1 mass composition KV1 In comparison to KV1 with the commercial dimethyl urea accelerator Dyhard UR500, K1 shows that the accelerators according to the invention (polymer B2) achieve comparable bond strengths on curing. However, the shelf life of the two adhesives is very different. K1 shows no change in the DSC heat of reaction either on storage for 10 days at 40 ° C. or for 10 days at 60 ° C. (Lf ₄ o = Lf ₆ o = 100%).

In contrast, the adhesive reacted 59% with the commercial urea accelerator KV1 at 40 ° C storage after 10 days (Lf ₄ o = 41%) and fully cured at 60 ° C storage after 10 days.

Claims

A method for free-radical polymerization for the production of a copolymer, comprising or consisting of the polymerization of at least one monomer A which contains at least one unsaturated -C = C double bond and has a T _g > 0 ° C, determined on the basis of the homopolymer of the monomer A. by means of DSC measurement; at least one monomer B which contains an aromatic heterocyclic group which contains at least one nitrogen atom in the ring and which furthermore contains at least one unsaturated -C = C double bond; and optionally at least one monomer C which contains at least one unsaturated - C =C double bond and is different from monomers A and B; in the presence of at least one free radical initiator and optionally at least one regulator; wherein the at least one monomer A is contained in at least 30 mol% based on the total monomers of the copolymer.

Process according to claim 1, characterized in that i) the at least one monomer A has a molecular weight of less than 1000 g / mol; and / or ii) the at least one monomer A does not comprise a nitrogen-containing aromatic heterocyclic group; and / or iii) the at least one monomer A is selected from one of the following groups iiia) to iiid), iiia) acenaphthylene, maleic anhydride, N-phenylmaleimide, N-vinylpyrrolidone, 2-vinylnaphthalene, acrylamide, N-vinylcaprolactam, itaconic anhydride, tert .- butyl methacrylate, dihydrodicyclopentadienyl acrylate, isobornyl methacrylate, tert-butyl acrylate, acrylic acid, methyl methacrylate, styrene and styrene derivatives, N, N-dimethylacrylamide, N-tert-butyl acrylamide, N-isopropyl acrylamide,

Isobornyl acrylate, acrylonitrile, methacrylonitrile, hydroxyethyl methacrylate, cyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, 3,4-

Epoxycyclohexylmethyl methacrylate, glycidyl methacrylate, ethyl methacrylate, benzyl methacrylate, phenyl methacrylate, iso-butyl methacrylate, stearyl acrylate, vinyl acetate, n-butyl methacrylate, methyl acrylate, 2-phenoxyethyl acrylate, 2- (3-toloidylureido) ethyl methacrylate, or mixtures thereof; or iiib) acenaphthylene, maleic anhydride, N-phenylmaleimide, N-vinylpyrrolidone, 2-

Vinyl naphthalene, acrylamide, N-vinylcaprolactam, itaconic anhydride, tert-butyl methacrylate, dihydrodicyclopentadienyl acrylate, isobornyl ethacrylate, tert-butyl acrylate, acrylic acid, methyl ethacrylate, styrene and styrene derivatives, N, N-dimethylacrylamide, N-tert-butyl acrylamide,

Epoxycyclohexylmethyl methacrylate, glycidyl methacrylate, ethyl methacrylate, benzyl methacrylate, phenyl ethacrylate, iso-butyl methacrylate, 2- (3-toloidylureido) ethyl methacrylate, or mixtures thereof; or iiic) acenaphthylene, maleic anhydride, N-phenylmaleimide, N-vinylpyrrolidone, 2-

Vinyl naphthalene, acrylamide, N-vinylcaprolactam, itaconic anhydride, tert-butyl methacrylate, dihydrodicyclopentadienyl acrylate, isobornyl methacrylate, tert-butyl acrylate, acrylic acid, methyl methacrylate, styrene and styrene derivatives, N, N-dimethylacrylamide, N-isopropyl acrylamide, N-tert-butyl acrylamide

Isobornyl acrylate, acrylonitrile, methacrylonitrile, hydroxyethyl methacrylate, cyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, phenyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, glycidyl methacrylate, 2- (3-toloidylureido) ethyl methacrylate, or mixtures thereof; or iiid) acenaphthylenes, maleic anhydride, N-phenylmaleimide, N-vinylpyrrolidone,

2-vinylnaphthalene, acrylamide, N-vinylcaprolactam, itaconic anhydride, tert-butyl methacrylate, dihydrodicyclopentadienyl acrylate, isobornyl methacrylate, tert-butyl acrylate, acrylic acid, methyl methacrylate, styrene and styrene derivatives, N, N-dimethylacrylamide, N-tert-butyl acrylamide, N-tert-butyl acrylamide

Isobornyl acrylate, acrylonitrile, methacrylonitrile, phenyl methacrylate, 2- (3-toloidylureido) ethyl methacrylate, or mixtures thereof

Method according to one of the preceding claims, characterized in that the at least two different monomers A are polymerized, preferably one monomer A is N-phenylmaleimide and the further monomer A is selected from acenaphthylenes, maleic anhydride, N-vinylpyrrolidone, 2-vinylnaphthalene, acrylamide, N-vinylcaprolactam, itaconic anhydride, tert-butyl methacrylate, dihydrodicyclopentadienyl acrylate, isobornyl methacrylate, tert-butyl acrylate, acrylic acid, methyl methacrylate, styrene and styrene derivatives such as 4-acetoxystyrene, alpha-methyl styrene, N-methyl styrene, 4-methyl styrene, for example , N-tert- Butyl acrylamide, N-isopropyl acrylamide, isobornyl acrylate, acrylonitrile, methacrylonitrile, hydroxyethyl methacrylate, cyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, glycidyl methacrylate, ethyl methacrylate, ethyl methacrylate, methacrylate, methacrylate, methacrylate, acrylate, methacrylate, stacrylate, methacrylate, methacrylate, stacrylate, methacrylate, stacrylate, methacrylate, stacrylate, methacrylate, stacrylate, methacrylate, stacrylate, methacrylate, methacrylate, stacrylate, methacrylate, stacrylate, methacrylate, stacrylate, methacrylate, stacrylate, methacrylate, stacrylate, methacrylate -Phenoxyethyl acrylate and 2- (3-toloidylureido) ethyl methacrylate.

Process according to one of the preceding claims, characterized in that i) the at least one monomer B has a molecular weight of less than 2000 g / mol; and / or ii) the at least one monomer B, as an aromatic heterocyclic group which contains at least one nitrogen atom in the ring, contains imidazole, pyridine or derivatives thereof; and / or iii) that the aromatic heterocyclic group which contains at least one nitrogen atom in the ring is bonded to the polymer backbone of the resulting copolymer through a spacer group with 2 to 20 atoms; and / or iv) the at least one monomer B is contained in 20 to 70 mol% based on the total monomers of the copolymer; and / or v) the at least one monomer B does not contain an —OH radical.

Process according to one of the preceding claims, characterized in that the molar ratio of the monomers A to the monomers B is from 30 to 60 to 40 to 70.

Method according to one of the preceding claims, characterized in that the at least one radical initiator is a UV radical initiator or a thermal radical initiator; and / or the at least one free radical initiator is contained in less than 10 mol% based on 100 mol% of the monomers A to C.

Process according to one of the preceding claims, characterized in that the polymerization i) is carried out in at least one organic solvent; and / or ii) is carried out under a protective gas atmosphere; and / or iii) that at least one regulator is also used. 8. The method according to any one of the preceding claims, characterized in that i) the polymerization is carried out with heating and / or ii) the reaction time is at least 1 hour.

9. Copolymer obtainable by radical polymerization according to a process of claims 1 to 8.

10. An adhesive tape comprising at least one layer of a pressure-sensitive adhesive, the adhesive comprising a polymeric film-forming matrix and a curable composition, the curable composition comprising one or more epoxy resins and at least one curing reagent for epoxy resins, characterized in that the curing reagent comprises at least one copolymer according to claim 9 and comprises at least one hardener.

11. Adhesive tape according to Claim 10, characterized in that at least one of the epoxy resins of the curable composition is an elastomer-modified epoxy resin and / or a fatty acid-modified epoxy resin.

12. Adhesive tape according to claim 10 or 11, characterized in that one or more thermoplastic polyurethanes or one or more non-thermoplastic elastomers are used in whole or in part as the polymeric film-forming matrix.

13. Use of the copolymer according to claim 9 as an accelerator in the curing reagent for adhesives, in particular adhesives based on epoxy.