Multi-component epoxy resin composition with accelerated curing

Abstract

The present invention relates to a multi-component epoxy resin composition comprising:-a first component comprising:-at least one epoxy resin comprising more than one epoxy group per molecule on average; -optionally, at least one reactive diluent having one epoxy group per molecule; -optionally, further additives; and-a second component comprising:-at least one amine hardener for epoxy resins; -optionally further additives; and-a third component consisting of:-an aqueous solution of at least one metal salt wherein the solution contains 20 to 80 parts by weight, preferably 30 to 70 parts by weight, in particular 40 to 60 parts by weight of said metal salt, based on 100 parts by weight of water in the aqueous solution; wherein the weight ratio of the second component to the third component is from 100: 0.3 to 100: 10, preferably from 100: 1 to 100: 5. The combination of a water-based cure-promoting third component with a common two-component epoxy resin composition results in significant cure acceleration of the two-component epoxy resin composition without requiring heating and without adversely affecting the properties of the cured epoxy resin composition.

Description

TECHNICAL FIELD

[0001] The present invention relates to multi-component epoxy resin compositions, their use as adhesives, sealants or coatings, the use of additional components for accelerating the curing of two-component epoxy resin compositions, and a method for accelerating the curing of multi-component epoxy resin compositions. PRIOR ART

[0002] Epoxy resins offer an ideal matrix for the preparation of adhesives, sealants or coatings due to their excellent properties such as excellent chemical resistance, high thermal stability, good processability and high adhesive strength. Thus, epoxy adhesives are used in many different fields such as biochemistry, construction, marine, aerospace and refinish, etc. There are several types of curing agents for curing epoxy resins. A first distinction can be made between low temperature curing agents and high temperature curing agents. High temperature curing agents require the application of heat to complete crosslinking in a reasonable time. Representatives of high temperature curing agents are polycarboxylic acids and their anhydrides, polycarboxylic acid polyhydrazides, polyhydric phenols and dicyandiamide. On the other hand, among the commonly used low temperature curing agents, which usually do not require heating, are polyamines such as polymers of alkylene amines. Other very effective fast curing agents are imidazoles, mercaptans, amines (mainly cycloaliphatic amines, aliphatic amines and low molecular polyamide compounds) and complexes (e.g. boron trifluoride amine). The curing rate of amine curing agents, from fast to slow, is aliphatic amines > cycloaliphatic amines > low molecular polyamides > aromatic amines. For epoxy-based systems, the curing process of the selected resin and hardener determines the mechanical and thermal properties as well as the processability and the final application.

[0003] In particular in the construction market, especially at low temperatures, there is a need to even more rapidly accelerate the curing process of epoxy systems, thus reducing production time and repair downtime.

[0004] In order to increase the curing rate of epoxy resins, compounds known as accelerators are usually used to reduce the curing time of the system. Current solutions include, for example, the addition or in situ generation of hydroxyl-containing substances or the increase of the curing temperature by exothermic processes within the composition or by external heating.

[0005] Higher temperatures favor curing, colder temperatures slow it down.

[0006] Promoters commonly used in the low temperature curing of epoxy resins are phenols such as hydroxybenzene and cresols. These compounds have the advantage of being readily soluble in the most commonly used liquid amino curing agents and liquid epoxy resins at ambient temperature and also exhibit good promoting activity. However, typical phenolic promoters impart odor and toxicity to the resins which precludes their use in certain applications. Benzoyl alcohol, another promoter used, is considered a semi-volatile organic compound (SVOC). SVOCs tend to have higher molecular weights and boiling points than the notorious VOCs, which means they are less likely to become vapors at room temperature. However, this does not mean they are less hazardous. In fact, their presence in adhesives, even at very low concentrations, precludes their classification as low-emission products EMICODE certified, which in the construction market is becoming a new standard and one of the central elements in the customer's purchase decision.

[0007] To overcome these drawbacks, the addition of other curing catalysts or promoters to epoxy compositions has been investigated and also documented in the literature.

[0008] For example, US4668736A teaches the use of metal salt catalysts, in particular selected from calcium nitrate, lanthanum nitrate and other metal salts having calcium, strontium or barium cations and perchlorate or triflate anions, to accelerate the curing of epoxy resin compositions. These salts are added in solid form or dissolved in solvents such as ethylene glycol ethyl ether and proposed in this publication as a good solution to accelerate the curing reaction of epoxy compositions based on glycidyl ether epoxy group-containing resins and amino-terminated curing agents. However the addition of solvents is generally undesirable in epoxy resin compositions as they can have an impact on the VOC rating and can alter the properties of the composition, for example by imparting a plasticizing effect or by reducing the adhesion properties by migrating to the surface of the composition.

[0009] US2003 / 130481 A1 discloses an assembly for forming an epoxy gel coating wherein the assembly comprises a hardener component containing an epoxy curing agent, a resin component containing a liquid epoxy resin and an aqueous promoter component consisting of an aqueous solution of inorganic nitrate salts such as ammonium, lithium, sodium, potassium or other nitrate salts. In particular, the promoter component is mixed with the resin component which then preferably contains 2 to 4 wt% of nitrate salt and 1 to 2 wt% of water. This disclosure teaches the use of a promoter to reduce the room temperature gel time of epoxy gel coatings without significantly altering the Tg of the cured gel coating.

[0010] US 2021 / 332181 A1 discloses curing agents for epoxy resins based on specific amine mixtures. Among the general teachings of this document, accelerators that can be included in the curing agents are mentioned. Among them, calcium nitrate is specifically discussed, which is advantageously used in combination with 2,4,6-tris(dimethylaminomethyl)phenol and preferably in the form of an aqueous solution having 20 to 70 wt.-% calcium nitrate. The mentioned advantages of using this accelerator combination are fast curing, especially at low temperatures, and high hardness of the cured composition.

[0011] EP 0 169 066 B1 discloses a two-component epoxy resin composition comprising a first component containing a compound with glycidyl ether epoxy groups and a second component containing an amino-terminated aliphatic polyether curing agent, and 1 to 10 parts by weight of at least one metal salt catalyst selected from calcium nitrate, lanthanum nitrate and metal salts having calcium, strontium or barium cations and perchlorate or triflate anions in at least one of the two components. The addition of these salts leads to an acceleration of the curing rate, but this document teaches that anhydrous metal salt catalysts are preferred because the presence of water, such as hydration water or water separately included in the composition, generally reduces the curing rate as measured according to exotherm.

[0012] JP 7 182 699 B2 discloses a hardener for epoxy resin compositions, which are particularly suitable for chemically fastening building elements in drilled holes. The hardener comprises at least one salt selected from nitrate salts, nitrite salts, halogen salts, triflate salts, which act as accelerators for curing the epoxy resin composition. In an exemplary experimental embodiment, the salt is dissolved in glycerol and added to the curing agent.

[0013] Furthermore, other authors have proposed the use of aromatic, heterocyclic or alicyclic polyamines as curing agents and salts of trifluoromethanesulfonic acid as catalysts, for example in US 4101459.

[0014] Fast curing epoxy resins prepared by the reaction of the diglycidyl ether of bisphenol A with isophorone diamine (IPD) and N-(3-aminopropyl)-imidazole (API) have also been recently reported, as disclosed in J. Appl. Polym. Sci. 2019, 136, 47950.

[0015] Although some of the above-mentioned catalysts can accelerate the curing rate, in many cases the mechanical properties such as peel strength and tensile strength are adversely affected as a result. As mentioned above, their use also hinders the advantageous classification of low-emission products EMICODE certification, which has become a new standard in the construction market.

[0016] These facts emphasize the necessity to consider other factors, such as toxicity, solubility, processing effects, end properties, regulatory issues, cost and ease of use, before selecting / developing a specific accelerator that matches well or is designed for a specific application.

[0017] Current two-component epoxy adhesives have high mechanical properties, good adhesion to a wide range of substrates and good durability in contact with concrete, but also have some limitations, such as limited curing rate at low temperatures. However, even though it is in principle possible to use heat externally or internally to accelerate the curing reaction, it is often difficult or even impossible to apply heat uniformly through thick adhesive layers, especially on construction sites.

[0018] In addition, most fast-curing epoxy adhesives also have a short pot life, which makes their use in large-area construction sites more complex.

[0019] It would be desirable to have an accelerator that can be easily used with almost any commercial two-component epoxy resin composition and that can accelerate its curing at low temperatures as low as, for example, 2°C by simply mixing it with the epoxy resin composition.

[0020] Therefore, there is a need for a simple, inexpensive, environmentally friendly accelerator that accelerates the curing of two-component epoxy resin compositions by mixing the accelerator, promotes the formation of mechanical properties quickly, while minimizing or eliminating any potential adverse effects on health and the environment. In addition, the accelerator should be odorless, not require special EHS labeling or ADR certification for transport, and should not adversely affect the performance of the accelerated two-component epoxy resin composition. SUMMARY

[0022] Therefore, it is an object of the present invention to provide a simple, inexpensive, environmentally friendly accelerator composition that accelerates the curing of two-component epoxy resin compositions by mixing the accelerator as an additional component into ordinary two-component epoxy resin compositions, promotes the formation of mechanical properties quickly, even at low temperatures, and does not have significant potential adverse effects on health and the environment. In addition, the accelerator should be storage-stable, easy to handle, and easy to prepare from readily available materials, and it should not adversely affect the performance of the accelerated two-component epoxy resin composition.

[0023] Surprisingly it was found that this object can be achieved by using an aqueous (water-based) solution of a metal salt as a further third component to be mixed into a two-component epoxy resin composition, thereby resulting in a multi-component epoxy resin composition as defined in claim 1. This not only leads to a significantly accelerated curing and faster development of mechanical properties of the epoxy resin composition, at least in preferred embodiments it even surprisingly improves the mechanical properties, in particular the compressive and flexural strength, of the two-component epoxy resin composition. Moreover, due to the fact that only very small amounts (e.g. < 3 wt.-% relative to the hardener component) of this third component need to be mixed in order to achieve these effects, the risk of altering the properties of the two-component epoxy resin composition (e.g. by imparting an undesired plasticizing effect) is very low. Thus, it can be added to almost any amine-cured two-component epoxy resin composition without the need to reformulate or adjust the epoxy resin composition components.

[0024] The first aspect of the present invention relates to a multi-component epoxy resin composition comprising

[0025] - a first component K1 comprising:

[0026] - at least one epoxy resin A containing on average more than one epoxy group per molecule;

[0027] - optionally, at least one reactive diluent having one epoxy group per molecule;

[0028] - optionally, further additives; and

[0029] - a second component K2 comprising:

[0030] - at least one amine hardener B for epoxy resins;

[0031] - optionally, further additives; and

[0032] - a third component K3 consisting of:

[0033] - an aqueous solution of at least one metal salt M, wherein the solution contains 20 to 80 parts by weight, preferably 30 to 70 parts by weight, in particular 40 to 60 parts by weight of the metal salt M, based on 100 parts by weight of water in the aqueous solution;

[0034] wherein the weight ratio of component K2 to component K3 is 100:0.3 to 100:10, preferably 100:1 to 100:5.

[0035] The main advantages achieved with this multi-component epoxy resin composition over prior art existing solutions include:

[0036] The third (accelerator) component of the present invention is tasteless and non-toxic and it does not require special EHS labeling or ADR, thus even suitable for DIY applications. In addition to the beneficial EHS properties, the accelerator component is very simple and cheap to make, based on readily available raw materials, and is storage stable under any environmental conditions and exposure to air, sunlight, heat and humidity.

[0037] The acceleration effect is achieved even at low temperatures as low as 2°C and does not require heating.

[0038] By adding the third component as defined in claim 1, the final mechanical and adhesive properties of the cured accelerated epoxy resin composition are not significantly adversely affected. Moreover, at least in the preferred embodiments, the accelerator component surprisingly even improves some key mechanical properties of the cured accelerated two-component epoxy resin composition after curing, including compressive strength and flexural strength.

[0039] In addition, due to the acceleration of the curing of the two-component epoxy resin composition even at low temperatures as low as 2°C the addition of the third accelerator component enables the use of otherwise slowly curing two-component epoxy resin compositions in applications where heating is not possible. This eliminates or reduces the necessity to formulate additional epoxy resin compositions for each specific application.

[0040] Further aspects of the present invention are the subject of the additional independent claims. Especially preferred embodiments are the subject of the dependent claims. DETAILED DESCRIPTION

[0042] Throughout the text, the prefix “poly” in “polyisocyanate”, “polyol” or “polyphenol” for example denotes a molecule formally containing two or more of the respective functional groups.

[0043] The term “primary diamine” used in the present invention means a diamine having two terminal primary amino groups, which does not contain additional secondary amino groups. It has been proven that the introduction of secondary amino groups in the molecule is disadvantageous for the branching possibility in the continuous reaction of the amino-terminated impact strength modifier according to the present invention.

[0044] “Impact strength modifier” herein means an additive to an epoxy resin matrix, which leads to a significant increase in toughness of the cured matrix, even with small amounts of addition, in particular 0.1-15 wt.%, so that higher bending, tensile, impact or shock stresses can be withstood before the matrix breaks or cracks. Typically, the impact peel strength according to ISO 11343 is used as a measure of impact strength. Here, the breaking energy (BE) is expressed as the area under the measurement curve (from 25% to 90% according to ISO 11343). Typically, the impact peel strength according to ISO 11343 is used as a further measure of impact strength.

[0045] The term "modulus of elasticity" means the modulus of elasticity (in the range of elongation of 0.05 to 0.25%) measured according to DIN EN ISO 527, if not stated otherwise.

[0046] The term "polymer" used in this document means on the one hand a collection of chemically uniform macromolecules which are produced by a polymerization reaction (polyaddition, polycondensation, polymerization) whereas the macromolecules differ in their degree of polymerization, molecular weight and chain length. On the other hand, the term also includes derivatives of said collection of macromolecules which are produced by a polymerization reaction, i.e. compounds which are obtained by reaction (e.g. addition or substitution) of functional groups in the intended macromolecule and which can be chemically uniform or chemically non-uniform. Furthermore, the term also includes so-called prepolymers, i.e. reactive organic pre-adducts whose functional groups participate in the formation of macromolecules.

[0047] In this context, the use of the term "independently of each other" in connection with substituents, moieties or groups shall be interpreted that substituents, moieties or groups of the same name can be present at the same molecule with different definitions at the same time.

[0048] The term "room temperature" ("RT") means a temperature of 23 °C, if not stated otherwise.

[0049] All industrial standards and norms cited are, if not stated otherwise, directed to the latest version at the time of first filing of this patent application.

[0050] The term "weight" means in this context the mass of a compound or composition measured in kilograms.

[0051] The abbreviation "ADR" stands for "Agreement on the International Carriage of Dangerous Goods by Road" of September 30, 1957, is a treaty of the United Nations of 1957 on the cross-border transport of hazardous materials.

[0052] The abbreviation "EHS" stands for "Environment, Health and Safety".

[0053] Component K1

[0054] The first component K1 comprises:

[0055] - at least one epoxy resin A which contains on average more than one epoxy group per molecule;

[0056] - optionally at least one reactive diluent which has one epoxy group per molecule;

[0057] - optional further additives.

[0058] The first component K1 comprises at least one epoxy resin A which contains on average more than one epoxy group per molecule.

[0059] The epoxy resin A comprised in the first component K1 of the composition can be any conventional di- or polyfunctional epoxy resin used in the art. Suitable epoxy resins can be obtained, for example, from the reaction of an epoxide compound, such as epichlorohydrin, with a polyfunctional aliphatic or aromatic alcohol, i.e. diol, triol or polyol. One or more epoxy resins can be used.

[0060] The epoxy resin A which contains on average more than one epoxy group per molecule is preferably a liquid epoxy resin and / or a solid epoxy resin.

[0061] The term "solid epoxy resin" is well known to those skilled in the art of epoxides and is used in contrast to "liquid epoxy resin". Solid resins have a glass transition temperature above room temperature, i.e. they can be comminuted at room temperature into a free-flowing powder.

[0062] Particularly diglycidyl ethers which are suitable as liquid or solid epoxy resins are, inter alia, compounds of the formula (I)

[0063]

[0064] in which R 4 is a divalent aliphatic or mononuclear aromatic or binuclear aromatic radical.

[0065] Examples of such diglycidyl ethers are, inter alia, diglycidyl ethers of dihydric alcohols, such as ethylene glycol, butylene glycol, hexanediol or octanediol glycidyl ether, cyclohexanedimethanol diglycidyl ether, neopentyl glycol diglycidyl ether; 30

[0066] Diglycidyl ethers of dihydric, low to high molecular weight polyether polyols, such as polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether;

[0067] Diglycidyl ethers of di- and optionally trihydric phenols, which are to be understood not only as pure phenols, but also as optionally substituted phenols.

[0068] ​The type of substitution can be manifold. In particular, this is understood to mean a substitution directly on the aromatic ring bonded to the phenolic OH group. Furthermore, phenol is understood to mean not only mononuclear aromatic compounds, but also polynuclear or fused aromatic or heteroaromatic compounds having a phenolic OH group directly on the aromatic or heteroaromatic compound. As biphenols and optionally triphenols, for example 1,4-dihydroxybenzene, 1,3-dihydroxybenzene, 1,2-dihydroxybenzene, 1,3-dihydroxytoluene, 3,5-dihydroxybenzoic acid ester, 2,2-bis(4-hydroxyphenyl)propane (= bisphenol-A), bis(4-hydroxyphenyl)methane (= bisphenol-F), bis(4-hydroxyphenyl)sulfone (= bisphenol-S), naphthalene-m-phenol, dihydroxynaphthalene, dihydroxyanthraquinone, dihydroxydiphenyl, 3,3-bis(p-hydroxyphenyl)phthalide, 5,5-bis(4-hydroxy-phenyl)hexahydro-4,7-methanoindan, phenolphthalein, fluorescein, 4,4'-[bis(hydroxyphenyl)-1,3-phenylenebis(1 -methyl- ethylene)] (= bisphenol-M), 4,4'-[bis(hydroxyphenyl)-1,4-phenylenebis(1 -methyl- ethylene)] (= bisphenol-P), 2,2'-diallyl-bisphenol-A, diphenols and dimethylphenols prepared by reacting phenol or cresol with diisopropylbenzene, phloroglucinol, bile acid esters, phenol or cresol novolaks having an -OH functionality of 2.0 to 3.5 and all isomers of the aforementioned compounds.

[0069] The preferred solid epoxy resins A have the formula (II)

[0070]

[0071] In this formula, the substituents R' and R" are each independently H or CH3. Furthermore, the value of the index s is > 1.5, in particular 2 to 12.

[0072] Such solid epoxy resins are commercially available, for example from DOW, Huntsman or Hexion.

[0073] The person skilled in the art refers to compounds of the formula (II) with the index s of 1 - 1.5 as semi-solid epoxy resins. For the present application, they are likewise considered to be solid resins. However, preferred are epoxy resins in the narrower sense, i.e. with a value of the index s of > 1.5.

[0074] The preferred liquid epoxy resins A have the formula (III)

[0075]

[0076] In this formula, the substituents R'" and R"" are each independently H or CH3. Furthermore, the value of the index r is 0 - 1. Preferably, the value of r is less than 0.2.

[0077] Thus, these are preferably diglycidyl ethers of bisphenol A (DGEBA), bisphenol F and bisphenol A / F (here, the designation "A / F" means a mixture of acetone and formaldehyde, which is used as a reactant in its preparation). Such liquid resins are obtainable, for example, from Huntsman under the trade names GY 250, PY 304, GY 282 (Huntsman), or D.E.R. TM 331, or D.E.R. TM 330 (Olin), or Epikote 828 (Hexion).

[0078] Furthermore, so-called novolaks are suitable epoxy resins A. These are in particular of the formulae:

[0079] wherein R2= CH2, R1= H or methyl and z = 0 to 7.

[0080] In particular, they are phenol or cresol novolaks (R2= CH2).

[0081] Such epoxy resins are commercially available under the trade names EPN or ECN and 556 from Huntsman, or in the product line D.E.N. TM from Dow Chemical.

[0082] Preferably, the epoxy resin A is a liquid epoxy resin of formula (III). In an even more preferred embodiment, the thermally curable epoxy resin composition contains at least one liquid epoxy resin of formula (III) and at least one solid epoxy resin of formula (II).

[0083] Particularly preferred are bisphenol A diglycidyl ether, bisphenol F diglycidyl ether or bisphenol A / F diglycidyl ether, in particular GY 240, GY 250, GY 281, GY282, GY 285, PY 304 or PY 720 (all from Huntsman), or 330, 331, 332, 336, 351, 352, 354 or ​356 (all from Olin), or novolak glycidyl ethers.

[0084] Preferred are novolak glycidyl ethers derived from phenol-formaldehyde novolaks, which are also known as epoxy phenol novolak resins.

[0085] Such phenolic glycidyl ethers are commercially available, for example from Olin, Huntsman, Momentive or Emerald Performance Materials. Preferred types are 431, 438 or 439 (from Olin), EPN 1179, EPN 1180, EPN 1182 or EPN 1183 (from Huntsman), 154, 160 or 161 (from Momentive) or 8250, 8330 or 8350 (from Emerald Performance Materials).

[0086] The proportion of epoxy resin A is preferably 10 to 50% by weight, in particular 15 to 40% by weight, more preferably 20 to 30% by weight, based on the weight of component K1.

[0087] In addition, the composition can optionally comprise at least one reactive diluent having one epoxy group per molecule in component K1. Small molecule diglycidyl ethers can also be used as additional reactive diluents.

[0088] These reactive diluents are in particular:

[0089] - monofunctional saturated or unsaturated, branched or unbranched, cyclic or open-chain C4-C 30 glycidyl ethers of alcohols, in particular selected from butanol glycidyl ether, hexanol glycidyl ether, 2-ethylhexanol glycidyl ether, allyl glycidyl ether, tetrahydrofurfuryl and furfuryl glycidyl ether, trimethoxysilyl glycidyl ether.

[0090] - difunctional saturated or unsaturated, branched or unbranched, cyclic or open-chain C2-C 30 glycidyl ethers of alcohols, in particular selected from ethylene glycol, butanediol, hexanediol or octanediol glycidyl ether, cyclohexanedimethanol diglycidyl ether and neopentyl glycol diglycidyl ether,

[0091] glycidyl ethers of tri- or polyfunctional, saturated or unsaturated, branched or unbranched, cyclic or acyclic alcohols, such as epoxidized castor oil, epoxidized trimethylolpropane, epoxidized pentaerythritol or polyglycidyl ethers of aliphatic polyols such as sorbitol, glycerol or trimethylolpropane.

[0092] glycidyl ethers of phenol and aniline compounds, in particular selected from the group consisting of phenyl glycidyl ether, cresyl glycidyl ether, p-tert-butyl phenyl glycidyl ether, nonyl phenol glycidyl ether, 3-n-pentadecenyl glycidyl ether (from cashew nut shell liquid), N,N-diglycidyl aniline and triglycidyl-p-aminophenol.

[0093] epoxidized amines, such as N,N-diglycidyl cyclohexylamine.

[0094] epoxidized mono- or di-carboxylic acids, in particular selected from the group consisting of diglycidyl neodecanoate, diglycidyl methacrylate, diglycidyl benzoate, diglycidyl phthalate, tetrahydrophthalate and hexahydrophthalate and di-glycidyl esters of dimer fatty acids and diglycidyl esters of terephthalic acid and trimellitic acid.

[0095] epoxidized di- or tri-functional, low to high molecular weight polyether polyols, in particular polyethylene glycol diglycidyl ether or polypropylene glycol diglycidyl ether.

[0096] Particularly preferred are hexanediol diglycidyl ether, cresyl glycidyl ether, p-tert-butyl phenyl glycidyl ether, polypropylene glycol diglycidyl ether and polyethylene glycol diglycidyl ether.

[0097] Advantageously, the total proportion of reactive diluents is 0.1 to 10% by weight, preferably 1 to 5% by weight, based on the weight of component K1.

[0098] Preferably, the weight ratio between the epoxy resin A and the epoxy group containing reactive diluents in component K1 is from 60 / 40 to 95 / 5, in particular from 70 / 30 to 95 / 10.

[0099] Preferably, the epoxy-functional compounds in the epoxy resin A and optional reactive diluents in component K1 are selected from the group consisting of liquid bisphenol A diglycidyl ether, liquid bisphenol F diglycidyl ether, C12 / C14 alkyl monoglycidyl ether, diglycidyl ether of 1,6-hexanediol, diglycidyl ether of 1,4-butanediol and combinations thereof.

[0100] In addition to these ingredients, component K1 can optionally contain other additives discussed below.

[0101] Component K2

[0102] The second component K2 comprises

[0103] - at least one amine hardener B for epoxy resins;

[0104] -Optional other additives.

[0105] The second component K2 firstly comprises at least one amine hardener B for epoxy resins.

[0106] The hardener is preferably contained in an amount of 4% to 50% by weight, preferably 5% to 40% by weight, in particular 7% to 25% by weight, based on the total weight of component K2.

[0107] The hardener B is preferably a compound or a mixture of compounds selected from poly(ethylene imine), polyamidoamine, amino-terminated butadiene / acrylonitrile copolymers and polyamines.

[0108] Examples of suitable hardeners B include, for example:

[0109] - aliphatic, cycloaliphatic or arylaliphatic primary diamines,

[0110] For example, ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 2-methyl-1,2-propylenediamine, 2,2-dimethyl-1,3-propylenediamine, 1,3-butanediamine, 1,4-butanediamine, 1,3-pentanediamine (DAMP), 1,5-pentanediamine, 1,5-diamino-2-methylpentane (MPMD), 2-butyl-2-ethyl-1,5-pentanediamine (C11-neodiamine), 1, 6-hexanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,2,4- and 2,4,4-trimethylhexamethylenediamine (TMD), 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,2-, 1,3- and 1,4-diaminocyclohexane, bis-(4-aminocyclohexane)methane (H 12 -MDA), bis-(4-amino-3-methylcyclohexyl)methane, bis-(4-amino-3-ethylcyclohexyl)methane, bis-(4-amino-3,5-dimethylcyclohexyl)methane, bis-(4-amino-3-ethyl-5-methylcyclohexyl)methane (M-MECA), 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (=isophoronediamine or IPDA), 2- and 4-methyl-1,3-diaminocyclohexane and mixtures thereof, 1,3- and 1,4-bis-(aminomethyl)cyclohexane, 2,5(2,6)-bis-(aminomethyl)-bicyclo[2.2.1]heptane (NBDA), 3(4),8(9)-bis-(aminomethyl)-tricyclo[5.2.1.0 2,6decane, 1,4-diamino-2,2,6-trimethylcyclohexane (TMCDA), 1,8-menthane diamine, 3,9-bis-(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane and 1,3- and 1,4-xylylenediamine;

[0111] aliphatic primary diamines containing ether groups,

[0112] for example bis(2-aminoethylether), 3,6-dioxaoctane-1,8-diamine, 4,7- dioxadecane-1,10-diamine, 4,7-dioxadecane-2,9-diamine, 4,9-dioxadodecane-1,12- diamine, 5,8-dioxadodecane-3,10-diamine, 4,7,10-trioxatridecane-1,13-diamine and higher oligomers of these diamines, bis-(3-aminopropyl)polytetrahydrofurane and other polytetrahydrofurandiamines in the molecular weight range of for example 350 to 2000, and polyoxyalkylenediamines. Generally, the latter are amination products of polyoxyalkylene glycols and are available for example under the name (From Huntsman), under the name Polyetheramin (from BASF) or under the name (From Nitroil). Particularly suitable polyoxyalkylenediamines are D-230, D-400, D-2000, XTJ-511, ED-600, ED-900, ED-2003, XTJ-568, XTJ-569, XTJ-523, XTJ-536, XTJ-542, XTJ-559, EDR-104, EDR-148, EDR-176; Polyetheramin D 230, Polyetheramin D 400 and Polyetheramin D 2000, PC DA 250, PC DA400, PC DA 650, and PC DA 2000;

[0113] polyamines having secondary amino groups,

[0114] for example diethylenetriamine (DETA), dipropylenetriamine (DPTA), bis- hexamethylenetriamine (BHMT), 3-(2-aminoethyl)aminopropylamine, N3-(3- aminopentyl)-1,3-pentanediamine, N5-(3-aminopropyl)-2-methyl-1,5- pentanediamine, N5-(3-amino-1 -ethylpropyl)-2-methyl-1,5-pentanediamine, N,N'-dibutyl ethylenediamine; N,N'-di-tert-butyl-ethylenediamine, N,N'-diethyl-1,6- hexanediamine, 1 -(1 -methylethylamino)-3-(1 -methylethylaminomethyl)-3,5,5- trimethylcyclohexane (JEFFAMINE®HT-4000 from Huntsman) 754), N4-cyclohexyl-2-methyl-N2-(2-methylpropyl)-2,4-pentanediamine, N,N'-dialkyl-1,3-xylylenediamine, bis-(4-(N-alkylamino)cyclohexyl)methane, 4,4'-trimethylenedipiperidine, N-alkylated polyetheramines, for example JEFFAMINE® types SD-231, SD-401, SD-404 and SD-2001 (from Huntsman);

[0115] - amine / polyepoxide addition products,

[0116] in particular the addition products of said polyamines with diepoxides in a molar ratio of at least 2 / 1, in particular in a molar ratio of 2 / 1 to 6 / 1 ;

[0117] - polyamidoamines

[0118] which are reaction products of a mono- or polybasic carboxylic acid or an ester or anhydride thereof, in particular of a dimer fatty acid, with an aliphatic, cycloaliphatic or aromatic polyamine, in particular a polyalkyleneamine such as DETA or triethylenetetramine (TETA), in particular the commercially available polyamidoamine JEFFAMINE® 100, 125, 140 and 150 (from Cognis), JEFFAMINE® 223, 250 and 848 (from Huntsman), JEFFAMINE® 3607, JEFFAMINE® 530 (from Huntsman), JEFFLINK® EH 651, EH 654, EH 655, EH 661 and EH 663 (from Cytec);

[0119] - polyethyleneimines (PEI)

[0120] These are branched polymeric amines derived from the polymerization of ethyleneimine. Suitable polyethyleneimines generally have an average molecular weight of 250 to 25,000 g / mol and contain tertiary, secondary and primary amino groups. Polyethyleneimines are available, for example, under the trade name Lupamin® (from BASF), for example Lupamin® FG, Lupamin®, Lupamin® G20 and Lupamin® PR 8515.

[0121] - cashew nutshell-based amines

[0122] These are reaction products of cardanol, the main component of cashew nut shell liquid (CNSL), with amines, resulting in phenalkamine structures. These are reusable raw materials with very good properties for use as hardener B.

[0123] Suitable polyamines as hardener B are in particular polyoxyalkylene diamines (Jeffamines®) with a molecular weight of less than 500 g / mol, such as D-230, Jeffamine D400, EDR-148), 4,7,10-trioxa-tridecane-1,13-diamine, 4,9-dioxa-dodecane-1,12-diamine, ethylenediamine and / or 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0 2,6 ]decane (TCD- manufactured by Celanese Chemicals). It has been shown that polyethyleneimines in particular with a molecular weight Mw of less than 100,000 g / mol, in particular less than 50,000 g / mol, are particularly suitable.

[0124] In particular, polyamines, which are preferably diamines or triamines, are selected from aliphatic diamines or triamines containing ether groups, in particular polyoxyalkylene diamines and polyoxyalkylene triamines; in particular polyoxyethylene diamines and triamines, polyoxypropylene diamines and triamines; polyoxybutylene diamines and polyoxybutylene triamines, amino-terminated polybutadienes and butadiene / acrylonitrile copolymers or mixtures thereof.

[0125] In particular, these are polyoxyalkylene polyamines with two or three amino groups, which are commercially available, for example, under the name Jeffamine® (from Huntsman Chemicals), under the name Polyetheramin (from BASF) or under the name PC (From Nitroil), as well as mixtures of the above-mentioned polyamines.

[0126] Furthermore, the hardener component K2 can comprise a promoter. Suitable promoters are substances which accelerate the reaction between amino groups and epoxy groups, in particular acids or compounds which can be hydrolyzed to acids, in particular organic carboxylic acids such as acetic acid, benzoic acid, salicylic acid, 2-nitrobenzoic acid, lactic acid, organic sulfonic acids such as methanesulfonic acid, p-toluenesulfonic acid or 4-dodecylbenzenesulfonic acid, sulfonic acid esters, other organic or inorganic acids such as in particular phosphoric acid, or mixtures of the aforementioned acids and acid esters; tertiary amines, for example in particular the already mentioned promoter B, or 1,4-diazabicyclo[2.2.2]octane, triethanolamine, imidazoles, for example in particular N-methylimidazole, N-vinylimidazole or 1,2-dimethylimidazole, salts of such tertiary amines, quaternary ammonium salts, in particular benzyltrimethylammonium chloride, amidines, in particular 1,8-diazabicyclo[5.4.0]undec-7-ene, guanidines, in particular 1,1,3,3-tetramethylguanidine, phenols, in particular bisphenols, phenol-formaldehyde resins or Mannich bases, for example in particular 2,4,6-tris(dimethylaminomethyl)phenol or 2,4,6-tris(N,N-dimethyl-4-amino-2-azabutyl)phenol, phosphites, for example in particular diphenyl phosphite or triphenyl phosphite, or compounds containing mercapto groups. Preferred promoters are acids, tertiary amines or Mannich bases.

[0127] Most preferred among these are salicylic acid or 2,4,6-tris(dimethylaminomethyl)phenol or 2,4,6-tris(N,N-dimethyl-4-amino-2-azabutyl)phenol or combinations thereof.

[0128] Further preferred as accelerators are compounds comprising at least one dimethylamino group, in particular benzyl dimethyl amine, alpha-methylbenzyl dimethyl amine, N,N-diethyl-N',N'-dimethyl-1,3-propanediamine, N,N-dimethylethanolamine, 3-(N,N-dimethylamino)propan-1 -ol, 2- or 4-(dimethylaminomethyl)phenol, 2,4- or 2,6-bis(N,N-dimethylaminomethyl)phenol, 2,4,6-tris(N,N-dimethylaminomethyl)phenol, 2,4,6-tris(N,N-dimethyl-4-amino-2-aza-butyl)phenol or, in particular, N,N,N',N'-tetramethyl-1,2-ethanediamine, N,N,N',N'-tetramethyl-1,3-propanediamine, N,N,N',N'-tetramethyl-1,4-butanediamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, N,N,N'N',N"-pentamethyldiethylenetriamine, N,N,N'N',N"-pentamethyldipropylenetriamine, N,N,N'N',N"-pentamethyl-N-(2-aminoethyl)-1,3-propanediamine, N,N-dimethyl-1,2-ethanediamine, N,N-dimethyl-1,3-propanediamine, N,N-dimethyl-1,4-butanediamine, N,N-dimethyl-1,6-hexanediamine, 2-(2-(dimethylamino)ethylamino)ethanamine, 2-(3-(dimethylamino)propylaminoethanamine, 3-(2-(dimethylamino)ethylamino)propanamine, 3-(3-(dimethylaminopropylamino))propylamine (DMAPAPA), bis(2-(N,N-dimethylamino)ethyl)amine or bis(3-(N,N-dimethylamino)propyl)amine.

[0129] Particularly preferred are N,N,N',N',N"-pentamethyldiethylenetriamine, 3-(3-(dimethylamino)propylamino)propylamine (DMAPAPA) or bis(3-(N,N-dimethylamino)propyl)amine. These accelerators are readily available, have a low odor and enable high compressive strengths, high adhesion and hardly any curing problems in cold. The most preferred accelerator is 3-(3-(dimethylamino)propylamino)propylamine (DMAPAPA). DMAPAPA has a low odor, is toxicologically safe and is commercially available.

[0130] Furthermore, the composition can comprise at least one impact strength modifier I in either or both of components K1 and K2.

[0131] The impact strength modifier I has the advantage of, for example, increasing the toughness of the epoxy resin composition.

[0132] Preferably, the composition comprises 3 to 25 wt.-%, preferably 4 to 20 wt.-%, in particular 5 to 15 wt.-%, based on the total weight of the sum of components K1 and K2, of at least one impact strength modifier I in one or both of components K1 and K2. This amount refers to the pure active impact modifier without solvents or other solid or liquid additives usually used for better storage, handling, dispersion, dilution or other purposes.

[0133] Suitable impact strength modifiers I include, for example, core-shell polymers. Core-shell polymers consist of an elastic core polymer and a rigid shell polymer. Particularly suitable core-shell polymers consist of a core (core) of an elastic acrylate or butadiene polymer, which is wrapped around a rigid shell of a rigid thermoplastic polymer. This core-shell structure is formed spontaneously by layering block copolymers or is predetermined by subsequent grafting through emulsion or suspension polymerization.

[0134] Preferred core-shell polymers are so-called MBS polymers, which are commercially available under the trade names from Arkema, under the trade names from Dow (formerly Rohm and Haas) or under the trade names from Zeon. Particularly preferred are core-shell polymer particles which already exist as dried polymer latices. Examples are the Silplus® from Wacker with a polysiloxane core and an acrylate shell. M23A, the radiation-crosslinked rubber particles of the NEP series manufactured by Eliokem, or the Orogan® from Lanxess or the Orogan® from Dow EXL. Further comparable examples of core-shell polymers are under the name Orofol® from Evonik Hanse GmbH (Germany). Also suitable are nanoscale silicates in an epoxy matrix, such as those offered by Evonik Hanse GmbH (Germany) under the trade name Nonopox.

[0135] Further suitable as impact strength modifiers I are liquid rubbers, which are carboxyl- or epoxide-terminated acrylonitrile / butadiene copolymers or derivatives thereof. Such liquid rubbers are, for example, available under the trade names (Formerly known as ) CTBN and CTBNX and ETBN from Emerald Performance Materials LLC. In particular derivatives of the epoxy group-containing elastomer-modified prepolymers, such as the product line Preferably the product line 36, from Company (Schill + Seilacher Group, Germany) or product line In another embodiment, the impact modifier is a polyacrylate liquid rubber, which is fully miscible with the liquid epoxy resin and only separates into droplets upon curing of the epoxy resin matrix. Such a polyacrylate liquid rubber is, for example, available from Dow (formerly Rohm and Haas) under the name 20208-XPA.

[0136] Of course, it is clear to the person skilled in the art that mixtures of liquid rubbers can also be used, in particular mixtures of carboxyl- or epoxide-terminated acrylonitrile / butadiene copolymers or derivatives thereof with epoxide-terminated or otherwise functionalized polyurethane prepolymers.

[0137] Also suitable as impact strength modifier I is the reaction product of a carboxylated solid nitrile rubber with an excess of epoxy resin.

[0138] Furthermore suitable as impact strength modifier I is a polymer of the formula (IV) which contains epoxy groups.

[0139]

[0140] wherein, R 7 is the divalent radical of a carboxyl-terminated butadiene / acrylonitrile copolymer (CTBN) after removal of the terminal carboxyl groups. The radical R 4 is as defined and described above for formula (I).

[0141] Such an epoxy-functional impact modifier should only be present in component K1.

[0142] Also suitable as impact strength modifier I is a polymer of the formula (V).

[0143]

[0144] In this formula, n and n' are each, independently of one another, a value from 0 to 7, preferably 0 or 1 or 2, with the proviso that n + n' is a value from 1 to 8, in particular 1 or 2.

[0145] Furthermore, R 1 is a linear or branched polyurethane prepolymer which is terminated with n + n' isocyanate groups after removal of all terminal isocyanate groups. R 2 and R 3 are each, independently of one another, an aliphatic, cycloaliphatic, aromatic or araliphatic radical having 1 to 20 C atoms and optionally a heteroatom selected from O, N and S, in particular O and N.

[0146] If the substituents R 2 and R3 If the substituent R is reactive toward epoxy groups, the impact strength modifier I of formula (V) is part of component K2. 2 and R 3 If the impact modifier I of formula (V) is reactive toward amino groups, it is part of the hardener component K1. Such impact modifiers that are non-reactive or compatible with both components K1 and K2 can be incorporated into one or both components K1 or K2. This principle applies to all impact modifiers, not just those of formula (V).

[0147] In a preferred embodiment of the impact strength modifier according to formula (V), R 1 is a linear polyurethane prepolymer containing at least n+n' terminal isocyanate groups after removal of n+n' terminal isocyanate groups;

[0148] R 2 and R 3 It is the residue of cardanol after removing the hydroxyl H atom and is bonded through an oxygen atom.

[0149] Cardanol (CAS Registry Number: 37330-39-5) is a phenolic lipid derived from anacardic acid and is the primary component of cashew nut shell liquid (CNSL), a byproduct of cashew processing. The substance's name is derived from the abbreviation of the genus Anacardium, which includes the cashew tree (Anacardium occidentale). In addition to being a particularly effective impact strength modifier, this cardanol-capped impact modifier I has the advantage of being partially based on natural, renewable resources and is inexpensive.

[0150] Cardanol is available, for example, under the trade name NC-700 is commercially available from Cardolite Corporation.

[0151] Also suitable as impact strength modifier I are block copolymers, in particular solid block copolymers. Block copolymers can be obtained by anionic or controlled radical polymerization of methacrylates with at least one other monomer having an olefinic double bond. Preferred monomers having an olefinic double bond are those in which the double bond is directly conjugated to a heteroatom or to at least one other double bond. In particular, monomers selected from styrene, butadiene, acrylonitrile and vinyl acetate are suitable. Preferred are acrylate-styrene-acrylic acid (ASA) copolymers, such as those known under the name 1020 is available from GE Plastics. Particularly preferred block copolymers are block copolymers of methyl methacrylate, styrene and butadiene. Such block copolymers are available, for example, as triblock copolymers from Arkema under the group name SBM.

[0152] Also suitable as impact strength modifiers I are amino-terminated acrylonitrile / butadiene copolymers, which are part of the hardener component K2.

[0153] Also suitable as impact strength modifiers I are epoxy-terminated polyurethane polymers, in which a prepolymer is first prepared from di- / triisocyanates, polymer polyols and alkoxylated bisphenols and then reacted with an epoxy compound containing primary or secondary hydroxyl groups. These are described in EP 1 972 646 A1.

[0154] Furthermore, suitable impact strength modifiers I are described in EP 2 917 254 A1 and EP 2 917 255 A1.

[0155] Preferably, the weight ratio of all epoxy-functional compounds in the composition (e.g., epoxy resin A, reactive diluent) to the pure impact modifier I in the composition (without any solvent, additives, etc.) is 1 to 3 (w / w), preferably 1.2 to 2.9 (w / w), and more preferably 1.3-2.7 (w / w). This ratio enables particularly effective toughening of the composition, so that beneficial mechanical properties can be achieved using a wide range of different impact modifiers I. It is worth noting that epoxy-functional impact modifiers are not considered epoxy-functional compounds in this calculation, but are always considered impact modifier I. Impact modifiers functionalized in other ways (e.g., having amino groups) are of course always counted as impact modifier I in the calculation of the weight ratio.

[0156] Furthermore, the composition preferably comprises at least one filler F in either or both of components K1 and K2.

[0157] Preferably, the composition comprises between 15% and 80% by weight, preferably between 17% and 70% by weight, in particular between 20% and 60% by weight, of at least one filler F in either or both components K1 and K2, based on the total weight of the combination of components K1 and K2.

[0158] The use of fillers is advantageous since they improve the aging resistance of the adhesive and have a favorable influence on the mechanical properties.

[0159] Suitable fillers F are inorganic and organic fillers, for example ground or precipitated calcium carbonate, optionally coated with fatty acids, in particular stearates, barium sulfate (barytes), talc, quartz powder, quartz sand, dolomite, wollastonite, kaolin, mica (potassium aluminum silicate), molecular sieves, aluminum oxide, aluminum hydroxide, silicon dioxide (pyrogenic or precipitated), cristobalite, cement, gypsum, flue dust, carbon black, graphite, metal powders such as aluminum, copper, iron, silver or steel, PVC powder or hollow spheres, such as solid or hollow glass spheres and organic hollow spheres.

[0160] Also suitable as fillers F are layered minerals, in particular layered minerals exchanged with organic ions. The ion-exchanged layered minerals can be cation-exchanged or anion-exchanged layered minerals. The adhesive can also contain both cation-exchanged and anion-exchanged layered minerals. Such layered minerals can have the additional advantage of being corrosion inhibitors. If this is the case and these minerals have a significant anti-corrosion effect, they are considered corrosion inhibitors within the meaning of the present invention, as discussed further below.

[0161] Therefore, cation-exchanged layered minerals are obtained from layered minerals in which at least some of the cations have been replaced by organic cations. Examples of such cation-exchanged layered minerals are particularly those mentioned in U.S. Patent No. 5,707,439 or U.S. Patent No. 6,197,849. Methods for preparing these cation-exchanged layered minerals are also described. Preferred layered minerals are phyllosilicates. Layered minerals are particularly preferably phyllosilicates, as described in U.S. Patent No. 6,198,849, column 2, line 38 to column 3, line 5, in particular bentonite. Layered minerals such as kaolinite or montmorillonite or hectorite or illite have proven to be particularly suitable.

[0162] Preferred cation-exchanging layered minerals are known to those skilled in the art under the names organoclays or nanoclays and are commercially available, for example under the series of names (BYK Additives&Instruments)or (BYK Additives&Instruments)、 (or (Nanocor Inc.) or (BYK Additives&Instruments).

[0163] Anion-exchanged layered minerals can be obtained from layered minerals in which at least some of the anions have been exchanged for organic anions. An example of an anion-exchanged layered mineral is hydrotalcite, in which at least part of the carbonate anions of the middle layer have been replaced by organic anions.

[0164] The filler F preferably comprises particles having an average particle size of at least 0.1 to 1 mm, preferably at least 0.2 to 2 mm, and in particular at least 0.5 to 5 mm. This offers the additional advantage that such large filler particles act as spacers, which ensure a sufficiently thick adhesive layer and prevent adhesive material from squeezing out when the reinforcing element S is pressed onto the applied adhesive.

[0165] The average particle size of the filler F is generally determined by methods such as dynamic light scattering or, preferably, sieve analysis according to ASTM C136-06.

[0166] Furthermore, the multi-component epoxy resin composition can comprise further additives in either or both of the components K1 and K2. These are, for example:

[0167] - solvents, film-forming assistants or extenders, such as toluene, xylene, methyl ethyl ketone, 2-ethoxyethanol, 2-ethoxyethyl acetate, benzyl alcohol, ethylene glycol, diethylene glycol butyl ether, dipropylene glycol butyl ether, ethylene glycol butyl ether, ethylene glycol phenyl ether, N-methylpyrrolidone, propylene glycol butyl ether, propylene glycol phenyl ether, diphenylmethane, diisopropyl naphthalene, mineral oil fractions such as Solvesso types (from Exxon), aromatic hydrocarbon resins, in particular of the type containing phenolic groups, sebacic esters, phthalic esters, organic phosphoric and sulfonic esters and sulfonamides;

[0168] - anticorrosives, also called corrosion inhibitors, in particular layered minerals, such as ground phlogopite and micronized muscovite, and modified hydrotalcites (MHTs), also called "layered double hydroxides" (LHDs), organic corrosion inhibitors, such as amines, ureas, mercaptobenzothiazoles (MBT), benzotriazoles and tolyltriazoles, aldehydes, heterocyclic nitrogen compounds, sulfur-containing compounds and acetylenic compounds, and also ascorbic acid, succinic acid, tryptamine, caffeine and extracts of natural substances;

[0169] - reactive diluents, such as the above-mentioned epoxy-reactive diluents, epoxidized soybean or linseed oil, compounds with acetoacetate groups, in particular acetoacetylated polyols, butyrolactone and also isocyanates and silicones with reactive groups;

[0170] - polymers, such as polyamides, polysulfides, polyvinylformal (PVF), polyvinylbutylal (PVB), polyurethanes (PUR), polymers containing carboxyl groups, polyamides, butadiene-acrylonitrile copolymers, styrene-acrylonitrile copolymers, butadiene-styrene copolymers, homopolymers or copolymers of unsaturated monomers, in particular of the group comprising ethylene, propylene, butylene, isobutylene, isoprene, vinyl acetate and alkyl (meth)acrylates, in particular chlorosulfonated polyethylene and fluorine-containing polymers, sulfonamide-modified melamine and clean montan wax;

[0171] - fibers, such as fibers of plastic, carbon or glass;

[0172] - pigments, such as titanium dioxide or iron oxide or organic pigments;

[0173] - rheology modifiers, such as in particular thickeners, such as sheet silicates such as bentonite, castor oil derivatives, hydrogenated castor oil, polyamides, polyurethanes, urea compounds, pyrogenic silicic acid, cellulose ethers and hydrophobically modified polyoxyethylenes;

[0174] - adhesion promoters, for example organic alkoxysilanes, such as 3-glycidoxypropyltrimethoxysilane, 3- aminopropyltrimethoxysilane, N-(2-aminoethyl)-3- aminopropyltrimethoxysilane, N-(2-aminoethyl)-N'- [3-(trimethoxysilyl)propyl]ethylenediamine, 3- ureidopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, vinyltrimethoxysilane, or the corresponding organosilanes with ethoxy or (poly)etheroxy groups instead of methoxy groups;

[0175] - oxidation, heat, light and UV radiation stabilizers;

[0176] - flame retardants, in particular compounds such as aluminum oxide (Al(OH)3; also known as ATH, "aluminum trihydrate"), magnesium hydroxide (Mg(OH)2; also known as MDH, "magnesium dihydrate"), ammonium sulfate ((NH4)2SO4), boric acid (B(OH)3), zinc borate, melamine borate and melamine cyanurate; phosphorus-containing compounds such as ammonium phosphate ((NH4)3PO4), ammonium polyphosphate, melamine phosphate, melamine pyrophosphate, triphenyl phosphate, diphenylcresyl phosphate, tricresyl phosphate, triethyl phosphate, tri-(2- ethylhexyl)phosphate, trioctyl phosphate, mono-, bis- and tris(isopropylphenyl)phosphate, resorcinol bis(diphenyl phosphate), resorcinol diphosphate oligomer, tetraphenyl resorcinol diphosphite, ethylenediamine diphosphate and bisphenol A bis(diphenyl phosphate); halogen-containing compounds such as chloroalkyl phosphates, in particular tris(chloroethyl)phosphate, tris(chloropropyl)phosphate and tris(dichloroisopropyl)phosphate, polybrominated diphenyl ethers, in particular decabromodiphenyl ether, polybrominated diphenyl ethers, tris[3-bromo-2,2-bis(bromomethyl)propyl]phosphate, tetrabromobisphenol A, bis(2,3-dibromopropyl ether) of bisphenol A, brominated epoxy resins, ethylene-bis(tetrabromophthalimide), ethylenebis(dibromonaphthalene dicarboxamide), 1,2-bis-(tribromophenoxy)ethane, tris(2,3-dibromopropyl)isocyanurate, tribromophenol, hexabromocyclododecane, bis(hexachlorocyclopentadieno)cyclooctane and chlorinated paraffins; and combinations of halogen-containing compounds and antimony trioxide (Sb2O3) or antimony pentoxide (Sb2O5);

[0177] - surface-active agents, for example wetting agents, flow control agents, degassing agents or defoamers;

[0178] - biocides, for example algicides, fungicides or substances which inhibit the growth of fungi.

[0179] It is clear and known to the person skilled in the art which additives can be added to the resin component K1 and which additives can be added to the hardener component K2. Here, in particular, it must be ensured that the storage stability is not impaired or only slightly impaired by these additives. It is therefore clear to the person skilled in the art that polyamines will react with the epoxide in the resin component K1 and can therefore only be contained in the hardener component K2.

[0180] In a preferred embodiment, the multi-component epoxy resin composition contains an additive in either or both of the components K1 and K2, which is preferably selected from adhesion promoters, wetting agents and degassing agents, in an amount of 0.1 to 5% by weight, preferably 0.25 to 4% by weight, in particular 0.5 to 3% by weight, based on the combined weight of components K1 and K2.

[0181] In the epoxy resin composition, the ratio of the number of amine groups that are reactive towards epoxy groups to the number of epoxy groups is preferably in the range from 0.7 to 1.5, in particular from 0.8 to 1.2.

[0182] In the epoxy resin composition, the weight ratio of epoxy resin A, hardener B, impact modifier I and filler F is preferably A:B:I:F = 1 : (0.25-1) : (0.25-1) : (1-4), in particular = 1 : (0.3-0.5) : (0.3-0.5) : (1.5-3.5).

[0183] Component K3

[0184] The third component K3 of the multi-component epoxy resin composition consists of an aqueous solution of at least one metal salt M, wherein the solution contains 20 parts by weight to 80 parts by weight, preferably 30 parts by weight to 70 parts by weight, in particular 40 parts by weight to 60 parts by weight, of the metal salt M, based on 100 parts by weight of water in the aqueous solution.

[0185] Furthermore, the weight ratio of component K2 to component K3 is in all embodiments 100:0.3 to 100:10, in particular 100:0.5 to 100:7.5, preferably 100:1 to 100:5, most preferably 100:1.5 to 100:3.

[0186] The metal salt M plays a crucial role in the present invention. However, this effect is only achieved if the salt is completely dissolved in water in the above-mentioned amount range. Surprisingly, it was found that an aqueous solution of the metal salt M leads to a synergistic effect which exceeds the effect of using the solid salt M and water alone. While an undissolved metal salt M can accelerate the curing of the epoxy resin composition and pure water can lead to a similar effect, the effect of the aqueous solution as defined above was found to have an unexpectedly higher accelerating effect, even leading to a surprising improvement of the mechanical properties of the cured epoxy resin composition.

[0187] Suitable metal salts M are in principle all water-soluble salts based on metal cations and inorganic or organic anions.

[0188] For example, salts of Na, Ca, Mg, K, Be, Sr, Ba, La and transition metals are suitable, as long as they are able to form a stable solution in water in the claimed range.

[0189] Preferred are magnesium salts or calcium salts, preferably calcium salts.

[0190] Most preferred is Ca, since calcium as metal cation used as accelerator is particularly active and leads to an improvement of the mechanical properties of the composition, is non-toxic, easily available and cheap.

[0191] Preferred anions of the metal salt M include chlorate and nitrate anions. Most preferred is nitrate. Nitrate leads to the particularly accelerating component K3 and surprisingly improves the mechanical properties of the cured epoxy resin composition. Furthermore, nitrate has low toxicity, is easily available and cheap.

[0192] Therefore, the most preferred metal salt M is Ca(N03)2.

[0193] Mixtures of different metal salts M in component K3 can be used.

[0194] Component K3 contains 20 to 80 parts by weight, preferably 30 to 70 parts by weight, in particular 40 to 60 parts by weight of the metal salt M, based on 100 parts by weight of water in the aqueous solution. Most preferably, a solution of about 50 parts by weight of the metal salt M dissolved in 100 parts by weight of water is used. This concentration leads to the best accelerating effect and it can be mixed into components K1 and K2 in an amount which is low enough so that the curing and the mechanical properties of the epoxy resin composition are not adversely affected.

[0195] Component K3 can be simply prepared by dissolving the metal salt M in water. Preferably, distilled water or osmosis purified water is used, but tap water can also be used if it is not heavily contaminated with substances which can interfere with the epoxy resin composition.

[0196] One advantage of the present invention is that component K3 can be prepared on site, which means that only the solid metal salt M has to be transported and stored, whereas component K3 can simply be prepared by dissolving the salt in the required amount in water, which is usually available. This provides the advantage of lower transportation costs and storage requirements.

[0197] Component K3 of the present invention can be used with almost any available two-component amine-cured epoxy resin composition and by increasing the concentration of the metal salt M a higher acceleration activity can be established when slower curing epoxy resin compositions are used.

[0198] In addition to water and the metal salt M, component K3 can contain further additives. These additives include colorants, solution stabilizers, surfactants, biocides, stabilizers and other additives which do not interfere with the homogeneity of the aqueous solution of component K3 or do not adversely affect the epoxy resin composition.

[0199] Components K1 and K2 and K3 of the epoxy resin composition are stored in separate containers and are only mixed just before or during application. Suitable containers for storing the resin K1 or hardener K2 components are in particular pails, tubs, bags, sachets, cans, cartridges or tubes. Component K3 can be stored in any water-proof container, for example a glass jar, bag, pail or any other suitable container. The components are recyclable, which means that they can be stored for months to a year or more before use without changing their respective properties to a degree relevant to their use. For the application of the epoxy resin adhesive, the resin and hardener components K1 and K2 and the accelerator component K3 are mixed together shortly before or during application.

[0200] The mixing of the components is carried out by suitable methods. The mixing can be continuous or batch-wise. If the mixing is carried out before application, care must be taken that the mixing and application of the components does not take too much time, as this can lead to disturbances, for example a slow or incomplete build-up of adhesion. The mixing is in particular carried out at ambient temperature, which is usually in the range of about 0-40°C, preferably about 5-30°C.

[0201] When the components are mixed, the curing is initiated by chemical reactions. In this case, the epoxy groups react with the amino hydrogen of the amino group and any other group which is reactive towards epoxy groups and ring-open to produce amino alcohol units. Further epoxy groups react with each other under anionic polymerization, in particular catalyzed by dimethylamino. The dissolved metal salt M further accelerates the curing. As a result of these reactions, the adhesive cures to a cross-linked material. It is known to the person skilled in the art that primary amino groups are "difunctional" towards epoxy groups, which means that they can react with two separate epoxy groups.

[0202] The curing takes place in particular at ambient temperature or at temperatures as low as 2°C. The curing usually takes place within a few hours to a few days until it is largely complete under the given conditions. Important influencing factors are the temperature, the stoichiometry and the presence of accelerators.

[0203] As a result of the curing reaction, a cured adhesive is obtained.

[0204] Preferably, the application and curing of the adhesive take place at ambient temperature, in particular at temperatures of 0 to 40°C, in particular 5 to 30°C. This makes the handling of the adhesive particularly simple and is particularly advantageous in outdoor, construction site and unheated industrial buildings.

[0205] A further aspect of the present application is a method for accelerating the curing of a multi-component epoxy resin composition, comprising the following steps:

[0206] a) providing a two-component epoxy resin composition consisting of a first component K1 and a second component K2 as described above;

[0207] b) providing a third component K3 as described above;

[0208] c) mixing the components K1, K2 and K3 in any order;

[0209] d) applying the mixture of components K1, K2 and K3 to at least one substrate;

[0210] e) allowing the applied mixture to cure spontaneously at a temperature of at least 2°C.

[0211] All preferred embodiments of components K1, K2 and K3 described above further for the composition itself also apply to the method.

[0212] In a preferred embodiment of the method, in step d) the mixture is cured at a temperature of 5°C to 30°C, preferably 10°C to 25°C.

[0213] In the same or other preferred embodiments of the method, the at least one substrate is selected from the group consisting of concrete, mortar, cement screed, fiber cement, brick, tile, natural stone, masonry brick, steel, copper, iron, aluminum, wood, carbon fiber fabric, polyester, PVC, epoxy resin, glass and painted surfaces.

[0214] If desired, the surface of the substrate can be subjected to a surface treatment before the adhesive is applied. Such pre-treatment in particular comprises physical and / or chemical cleaning processes, such as grinding, sandblasting, shot blasting, brushing and / or blowing off, and further treatment with cleaning agents or solvents, or the application of an adhesion promoter, a primer solution or a primer.

[0215] In another preferred embodiment, the substrate is a part of a vehicle, in particular a road vehicle, an air vehicle or a water vehicle. The vehicle is preferably a bus, a truck, a train, a rail vehicle, an airplane, a helicopter, a ship, a boat or a submarine. Most preferred vehicles are large road vehicles, in particular buses or air vehicles.

[0216] Another aspect of the present application is the use of the multi-component epoxy resin composition as described above as an adhesive, a sealant or a coating, in particular for the construction or renovation of a building or a civil engineering structure.

[0217] All preferred embodiments of components K1, K2 and K3 of the multi-component composition further described above for the composition itself also apply to this use.

[0218] Another aspect of the present application is the use of an aqueous solution of at least one metal salt M as a curing accelerator for a two-component epoxy resin composition, wherein the solution contains 20 to 80 parts by weight, preferably 30 to 70 parts by weight, in particular 40 to 60 parts by weight of the metal salt M, based on 100 parts by weight of water in the aqueous solution.

[0219] The two components of the two-component epoxy resin composition refer to the epoxy resin component and the hardener component. Further components can also be used, for example a hydraulic binder component.

[0220] All commercially available two-component amine-cured epoxy resin compositions are suitable for this use. Such compositions are for example available under the trade names are commercially available. Examples thereof include - 31 +, - 32+ and - 42+ VLE Hot Climate, all from Sika.

[0221] Preferably, the two-component epoxy resin composition consisting of components K1 and K2 as described above is used as the two-component epoxy resin composition in this use. Also preferably, an aqueous solution of at least one metal salt M corresponding to component K3 as described above is used in this use. All preferred embodiments of components K1, K2 and K3 for the multi-component composition itself as further described above also apply to this use.

[0222] In a preferred embodiment of the use of an aqueous solution of at least one metal salt M as a curing accelerator for a two-component epoxy resin composition, the metal salt M is a calcium salt.

[0223] In the same or further preferred embodiments using an aqueous solution of at least one metal salt M as a curing accelerator for two-component epoxy resin compositions, the metal salt M is a nitrate or chlorate salt, preferably a nitrate salt. Examples

[0224] The examples given below further illustrate the application, but do not limit the scope of the application in any way and merely illustrate some possible embodiments. "Standard conditions" or "standard climate" ("NK") means a temperature of 23°C and a relative humidity (r.h.) of 50%.

[0225] Test methods

[0226] The following test methods were employed:

[0227] Compressive and flexural strength (EN-196-1)

[0228] Compressive strength (CS)

[0229] Prisms of the sample to be tested in the size of 40 x 40 x 160 mm were prepared in steel formwork. After 1 or 7 days at 23°C and 50% r.h., the samples were loaded under compressive stress at a constant rate of 2.4 kN / s with a pre-load of 0.5 kN until their breaking point or until the first crack appeared. The compressive strength values were read at maximum force in each case.

[0230] Flexural strength (FS)

[0231] Prisms of the sample to be tested in the size of 40 x 40 x 160 mm were prepared in steel formwork. After 7 days at 23°C and 50% r.h., the samples were loaded into a 3-point bending jig and bent at 0.5 kN / s until their breaking point. The force values of the bending strength were read at the breaking point in each case.

[0232] Tensile strength (TS), elongation at break (EOB) and modulus of elasticity (E-Mod) (DIN EN ISO 527) Cure rate measurements

[0233] Dumbbell-shaped bars with a thickness of 10 mm, a length of 150 mm, a platform length of 80 mm and a platform width of 10 mm were formed by applying and curing the mixed adhesive into silicone molds under standard climate. After a 7-day curing time (NK), the test specimens were removed from the mold. The test specimens were measured under standard conditions at a pulling speed of 2 mm / min. The tensile strength, the elongation at break and the modulus of elasticity of 0.05-0.25% were determined according to DIN EN ISO 527.

[0234] Time to peak exotherm temperature (TEPT)

[0235] In comparative studies the curing rate was determined by measuring the time to reach the exotherm peak temperature of the cured sample or by measuring the time to reach a certain Shore A hardness in the sample.

[0236] Time to Shore A hardness (TSAH)

[0237] The time to reach the exotherm peak temperature (TETP) and the exotherm peak temperature (T a ) were determined according to ASTM D 2471-99 on a 110 g freshly mixed sample in a plastic box with a diameter of 63 mm and a height of 65 mm under normal climate. The time to reach this temperature and the peak measured temperature were recorded. A faster reaching of the exotherm peak temperature means a faster curing rate. The respective curing temperature and other relevant conditions were stated in each experiment.

[0238] Two-component epoxy resin composition used

[0239] The time to reach a certain Shore A hardness was determined according to DIN 53505 on a sample with a layer thickness of 10 mm by measuring the time at 23 °C at 10 minute intervals. The respective curing temperature and other relevant conditions were stated in each experiment.

[0240] Examples of component K3

[0241] The two-component epoxy resin compositions used are listed in Table 1.

[0242] The adhesives in Table 1 are typical commercial two- or three-component epoxy resin compositions which have different formulations, for example differ in the fillers and the specific reactive ingredients. However, all of these adhesives in Table 1 comprise a first component K1 and a second component K2. In each of these adhesives the epoxy-functional compounds in the epoxy resin A and the optional reactive diluent in each respective component K1 are selected from the group consisting of liquid bisphenol A diglycidyl ether, liquid bisphenol F diglycidyl ether, C12 / C14-alkyl monoglycidyl ether, diglycidyl ether of 1,6-hexanediol, diglycidyl ether of 1,4-butanediol and combinations thereof. Furthermore, in each of these adhesives the respective second component K2 comprises a hardener B which is a compound or mixture of compounds selected from the group consisting of poly(ethyleneimine), polyamidoamine, amino-terminated butadiene / acrylonitrile copolymer and polyamine.

[0243]

[0244] Table 1 : Two-component epoxy resin adhesives used.

[0245] Accelerated cure rate test

[0246] A series of components K3 was prepared by dissolving specific amounts of each metal salt M in distilled water. Details of the components K3-1 to K3-9 thus prepared are shown in Table 2. The amounts in Table 2 describe the parts by weight of each metal salt added to 100 parts by weight of distilled water.

[0247] K3-1* K3-2 K3-3 K3-4 K3-5 K3-6 K3-7* K3-8* K3-9 Ca(NO3)2 0 25 50 80 0 0 0 0 0 Ca(ClO4)2 0 0 0 0 50 70 0 0 0 (NH4)H2PO4* 0 0 0 0 0 0 50 80 0 Mg(NO3)2 0 0 0 0 0 0 0 0 50

[0248] Table 2: Example components K3. * not according to the invention.

[0249] For testing, the homogeneous mixtures of the above components K3 detailed in Table 2 were combined with the hardener component K2 of each respective two-component epoxy resin composition used in each respective example. The epoxy resin component K1 and the hardener component K2 of each of the commercially available epoxy resin compositions were then mixed according to the respective commercially available product's instructions. For each example, the resin component K1 and the hardener component K2 (containing the respective component K3) were then processed into a homogeneous paste by a centrifugal mixer and immediately tested as described above.

[0250] Details and results of these experiments are shown in Table 3.

[0251] Mechanical property test

[0252] The following Tables 3 and 4 show the effect of the addition of component K3 on the curing rate as measured in the time to reach a Shore A hardness and the time to reach the exotherm peak temperature.

[0253]

[0254] Table 3: Time to reach Shore A = 40 measured at 20°C.

[0255] * not according to the invention.

[0256] 1 Parts by weight of each respective K3 mixed with 100 parts by weight of the respective hardener component K2. The ambient temperature during curing was 20°C in all experiments. The numerical results represent the time (in minutes) until a Shore A value of 40 was reached in each experiment. The shorter the time, the faster the curing rate, "n / m" means not measured.

[0257] Table 3 shows that the addition of the components K3 of the invention to the hardener component K2 leads to a significant acceleration of the curing within a broad concentration range. The addition of pure water leads initially to a small acceleration, but at higher concentrations this effect is reversed. This is also visible if too high amounts of the aqueous accelerator are added: when 16 parts by weight of the accelerator K3-3 are added, the curing is delayed by more than 24 hours in Combiflex and SD-32.

[0258]

[0259]

[0260] Table 4: Exotherm peak temperature T a and time to reach the same temperature (TEPT).

[0261] * not according to the invention.

[0262] 1 Parts by weight of respective K3-3 mixed with 100 parts by weight of the respective hardener component K2. The ambient temperature during curing was 20°C in all experiments. The numerical results indicate the compressive strength (CS) and the flexural strength (FS) in each experiment after curing: ** 6 hours at 20°C, *** 8 hours at 20°C, or **** 1 day at 20°C. "n / m" means not measured, "n / p" means that the value could not be measured due to insufficient curing. a in minutes and the exotherm peak temperature T a . The shorter the time, the faster the curing rate. "n / m" means not measured.

[0263] Table 4 shows that the exotherm peak temperature itself is hardly affected by the addition of component K3. However, when component K3 is added, a clear acceleration effect can be seen, which increases with increasing amount of addition. The time to reach the exotherm peak temperature is a clear indicator of the curing rate of the composition.

[0264] Test of metal salt M concentration in component K3

[0265] The following Tables 5a and 5b show the effect of the addition of component K3 on the mechanical properties of the cured epoxy resin adhesive.

[0266]

[0267] Table 5a: Compression and flexural strength tests.

[0268] * not according to the invention.

[0269] 1 Parts by weight of K3-3 mixed with 100 parts by weight of the respective hardener component K2. The ambient temperature during curing was 20°C in all experiments. The numerical results indicate the compressive strength (CS) and the flexural strength (FS) in each experiment after curing: ** 6 hours at 20°C, *** 8 hours at 20°C, or **** 1 day at 20°C. "n / m" means not measured, "n / p" means that the value could not be measured due to insufficient curing.

[0270]

[0271] Table 5b: Compression and flexural strength tests.

[0272] * not according to the invention.

[0273] 1Parts by weight of K3-3 mixed with 100 parts by weight of the corresponding hardener component K2. The ambient temperature during curing in all experiments was 20°C. The numerical results represent the compressive strength (CS) and the flexural strength (FS) after 1 day of curing at 20°C in each experiment. "n / p" means that the value could not be measured due to insufficient curing.

[0274] The results in Tables 5a and 5b show that the mechanical properties are surprisingly improved, especially at low addition levels of K3 relative to the corresponding K2. At higher addition levels, this effect is less pronounced or even reversed.

[0275] SD-31

[0276] The following Table 6 shows the effect of the metal salt M concentration of component K3 on the curing rate.

[0277] K3 in K2 1 ]] Combiflex n / m K3-2 175 180 K3-3 180 180 K3-4 175 Low cure temperature test

[0278] Table 6: Time to reach Shore A = 40 measured at 20°C.

[0279] 1 In each experiment, 1.5 parts by weight of K3 were mixed into 100 parts by weight of the corresponding hardener component K2. The ambient temperature during curing in all experiments was 20°C. The numerical results represent the time (in minutes) until the Shore A value reached 40 in each experiment. The shorter the time, the faster the curing rate. "n / m" means not measured.

[0280] The data given in Table 6 show that the acceleration effect is not linearly dependent on the salt concentration. Already very low salt concentrations show a significant acceleration effect. However, in component K3, at levels below 20 parts by weight of metal salt M per 100 parts by weight of water, it was found that the concentration is too low to have an acceleration effect without necessarily adding an excess of component K3, which can have undesired effects due to the addition of large amounts of water.

[0281] Test of different metal salts M in component K3

[0282] The following Tables 7 and 8 show the effect of the addition of component K3 on the curing rate, as measured in the time to reach a Shore A hardness, and on the mechanical properties of samples cured at low temperature after curing.

[0283]

[0284] Table 7: Time to reach Shore A = 40 measured at 2°C and 5°C.

[0285] * not according to the invention.

[0286] 11.5 parts by weight of K3 were mixed into 100 parts by weight of the respective hardener component K2. The ambient temperature during curing was 2°C or 5°C, respectively. The numerical results indicate the time (in hours) until a Shore A value of 40 was reached in each experiment. The shorter the time, the faster the curing rate.

[0287] Table 7 shows that the addition of component K3 has a significant accelerating effect on both investigated adhesives, even at low temperatures as low as 2°C. At the lower temperature of 2°C, the effect is even stronger than at 5°C.

[0288] SD-31

[0289] The following Tables 8 and 9 show the influence of other types of metal salts M in component K3 on the curing rate and the compressive strength after curing.

[0290]

[0291] Table 8: Time to reach Shore A = 40 at 20°C.

[0292] * not according to the invention.

[0293] 1 Parts by weight of the respective K3 mixed with 100 parts by weight of the respective hardener component K2. In all experiments, the ambient temperature during curing was 20°C. The numerical results indicate the time (in minutes) until a Shore A value of 40 was reached in each experiment. The shorter the time, the faster the curing rate. "n / m" means not measured.

[0294] K3 in K2 1 ]]> Combiflex Without K3* Dissolution test of metal salt M in component K3 50 46 K3-5 46 40 K3-6 57 49

[0295] Table 9: Compressive strength test.

[0296] * not according to the invention.

[0297] 1 In each experiment with component K3, 1.5 parts by weight of K3 were mixed into 100 parts by weight of the respective hardener component K2. The ambient temperature during curing was 20°C in all experiments. The numerical results indicate the compressive strength (CS) in each experiment after curing at 20°C for 1 day.

[0298] Tables 8 and 9 show that the effect of the invention can also be achieved with other metal salts M.

[0299] SD-31

[0300] The following Table 10 shows the influence of the state of dissolution of the metal salt M in component K3 on the curing rate. For this investigation, a comparative experiment with an undissolved (solid powder) salt M was carried out.

[0301] K3 in K2 1 ]] Combiflex SD-32 SD-42VLE Without K3* K3-3 (1.5 parts by weight) 166 76 50 360 n / m 94 50 25 275 Ca(NO3)2(1.5 parts by weight) *]] 162 105 n / m K3-3 (5 parts by weight) n / m 57 30 19 150 Ca(NO3)2(5 parts by weight) * 6H2O 141 K3-9 (1.5 parts by weight) 50 312 n / m 83 68 n / m n / m Mg(NO3)2(1.5 parts by weight) * 6H2O 135 92 n / m n / m

[0302] Table 10: Time to reach exotherm peak temperature (TEPT) at 20°C.

[0303] * not according to the invention.

[0304] 1 In each experiment, 1.5 or 5 parts by weight of K3 or a corresponding amount of a powder salt were mixed into 100 parts by weight of the respective hardener component K2 as defined in each experiment. The ambient temperature during curing in all experiments was 20°C. Numerical results indicate TEPT (min). "n / m" means not measured.

[0305] Tables 8-10 show that various different metal salts M have the ability to accelerate curing and to improve mechanical properties when used as aqueous solutions in component K3 of the invention. Table 10 on the other hand shows that the addition of salts in powder form does not lead to significant curing acceleration. Together with the further data described above including K3-1 this demonstrates the synergistic effect resulting from solutions of metal salts M as component K3 of the invention.

[0306] Further experiments were conducted with components K3-7 and K3-8 (as defined in Table 2). These components K3 did not accelerate curing nor did they improve the mechanical properties of the test epoxy resin compositions. This shows that non-metal salts such as (NH4)H2PO4 are not suitable in the sense of the invention.

Claims

1. A multi-component epoxy resin composition comprising: - a first component K1 comprising at least one epoxy resin A containing on average more than one epoxy group per molecule; - optionally, at least one reactive diluent having one epoxy group per molecule; - optionally, other additives; and - A second component K2 comprising: - at least one amine hardener B for epoxy resins; - optionally, other additives; and - A third component K3, consisting of: - an aqueous solution of at least one metal salt M, wherein the solution contains 20 to 80 parts by weight, preferably 30 to 70 parts by weight, in particular 40 to 60 parts by weight of the metal salt M, based on 100 parts by weight of water in the aqueous solution; The weight ratio of component K2 to component K3 is 100:0.3 to 100:10, preferably 100:1 to 100:

5.

2. The multi-component epoxy resin composition according to claim 1, characterized in that The metal salt M is a magnesium salt or a calcium salt, preferably a calcium salt.

3. The multi-component epoxy resin composition according to any one of claims 1 or 2, characterized in that The metal salt M is nitrate or chlorate, preferably nitrate.

4. The multi-component epoxy resin composition according to any one of claims 1 to 3, characterized in that The composition contains at least one impact strength modifier I in either or both of components K1 and K2.

5. The multi-component epoxy resin composition according to any one of claims 1 to 3, characterized in that The composition contains at least one filler F in either or both of components K1 and K2.

6. The multi-component epoxy resin composition according to any one of claims 1 to 5, characterized in that The molar ratio of all amino groups reactive toward epoxy groups in component K2 relative to the number of epoxy groups in component K1 is from 0.7 to 1.5, in particular from 0.8 to 1.

2.

7. The multi-component epoxy resin composition according to claim 1, characterized in that The amine in the amine hardener B in component K2 is selected from aliphatic polyamines, aromatic polyamines, alicyclic polyamines, polyaminoamides, phenalkamines, phenalkamides and mixtures thereof.

8. The multi-component epoxy resin composition according to any one of claims 1 to 7, characterized in that The epoxy functional compound in the epoxy resin A in component K1 and the optional reactive diluent are selected from liquid bisphenol A diglycidyl ether, liquid bisphenol F diglycidyl ether, C12 / C14-alkyl monoglycidyl ether, diglycidyl ether of 1,6-hexanediol, diglycidyl ether of 1,4-butanediol, and combinations thereof.

9. A method for accelerating the curing of a multi-component epoxy resin composition, comprising the steps of: a) providing a two-component epoxy resin composition consisting of a first component K1 and a second component K2 according to any one of claims 1 to 8; b) providing a third component K3 according to any one of claims 1 to 8; c) mixing components K1, K2 and K3 in any order; d) applying the mixture of components K1, K2 and K3 to at least one substrate; e) allowing the applied mixture to cure spontaneously at a temperature of at least 2°C.

10. The method according to claim 9, characterized in that In step d), the mixture is cured at a temperature of 5°C to 30°C, preferably 10°C to 25°C.

11. The method according to any one of claims 9 or 10, characterized in that The at least one substrate is selected from the group consisting of concrete, mortar, cement flooring, fiber cement, brick, tile, natural stone, masonry, steel, copper, iron, aluminum, wood, carbon fiber fabric, polyester, PVC, epoxy resin, glass, and painted surfaces.

12. Use of the multicomponent epoxy resin composition according to any of claims 1 to 8 as an adhesive, sealant or coating, in particular for the construction or renovation of building or civil engineering structures.

13. Use of an aqueous solution of at least one metal salt M as a curing accelerator for a two-component epoxy resin composition, wherein the solution contains 20 to 80 parts by weight, preferably 30 to 70 parts by weight, in particular 40 to 60 parts by weight of the metal salt M, based on 100 parts by weight of water in the aqueous solution.

14. Use according to claim 13, characterized in that The metal salt M is a magnesium salt or a calcium salt, preferably a calcium salt.

15. The use according to claim 13 or 14, characterized in that The metal salt M is nitrate or chlorate, preferably nitrate.

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