Latent curing accelerators

Abstract

To provide a storage-stable one-component epoxy resin composition.SOLUTION: There is provided a curable composition comprising (A) an epoxy resin containing on average more than one epoxy group per molecule; (B) a compound of formula A [-X-CO-CH2-CN]n (1), wherein A is hydrogen, an alkyl group or the like, X denotes -O- or -NR1-, wherein R1 is hydrogen, C1-C12 alkyl group which is unsubstituted or substituted, or the like, n is 1 to 4; and (C) a protected base in the form of an adduct or salt which is able to release a basic compound upon heating to a temperature greater than 70°C. The curable composition is storage-stable, allows processing over a longer period of time (pot-life) and produces cured products having outstanding mechanical and thermal properties.SELECTED DRAWING: None

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of European Patent Application No. 16205610.5, filed December 21, 2016, the entire disclosure of which is incorporated herein by reference.

[0002] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not applicable

[0003] Technical Field The present disclosure relates to a storage stable one-part epoxy resin composition comprising a cyanoacetic acid derivative as a curing agent and a protected base in the form of a salt or adduct as a curing initiator. [Background technology]

[0004] A one-liquid (1K) epoxy resin composition (1K system) consisting of an epoxy resin, a curing agent, and optionally a curing accelerator enables a long pot life in combination with a short curing time at high temperature.

[0005] A typical 1K epoxy resin composition may contain solid amines such as dicyandiamide or diaminodiphenylsulfone as hardeners. The solid state and associated particle size of the hardeners may impose constraints on certain manufacturing processes (e.g., for fiber-reinforced composites). Furthermore, these mixtures require storage at low temperatures (-18°C to +8°C).

[0006] Other approaches to stable 1K epoxy resin compositions may use accelerators of imidazoles, boron trihalogenide amine complexes, or cationic initiators for epoxy homopolymerization. Cured materials using such mechanisms typically suffer from brittleness and associated poor mechanical properties, requiring additives and formulations to compensate for property degradation.

[0007] Patent Document 1 proposes the use of cyanoacetic acid derivatives as curing agents in combination with phenol urea derivatives as curing accelerators. These epoxy resin compositions show high storage stability and provide cured products with good toughness, but the pot life is not sufficient for all applications. Furthermore, the storage stability achieved is entirely dependent on the concentration of the curing accelerator, making it difficult to achieve a balance between stability and reactivity. As a result, more stable compositions tend to react very slowly at moderate curing temperatures (below 120°C) or require higher temperatures to cure in an acceptable time. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Pat. No. 4,283,520 Summary of the Invention [Problem to be solved by the invention]

[0009] background Thus, the problem underlying the present disclosure is to improve the storage stability of epoxy resin compositions without sacrificing cure time under processing conditions. The present inventors have surprisingly found that by providing a protected base catalyst, storage stable 1K epoxy resin compositions can be produced. It has been unexpectedly found that the composition can be processed for a longer time (pot life) and rapidly produce a cured product with excellent mechanical and thermal properties. The present disclosure proposes a system for obtaining different reactivities in epoxy-based compositions by carefully selecting an acid to form a salt with a base or by adding a protecting group to the base. The base is then activated by heating the composition to a predetermined temperature. Such temperature depends on the protection mechanism used. [Means for solving the problem]

[0010] The present disclosure relates to (A) an epoxy resin containing an average of more than one epoxy group per molecule; Formula (B) (i) A[-X-CO-CH2-CN] n (1) (Wherein, A is hydrogen or unsubstituted or one or more C-C 12 Alkoxy groups, C1-C 12 Alkylcarbonyl group, C7-C 25 Arylcarbonyl group, hydroxyl group, amino group, C1-C 12 Alkylamino groups, C1-C 12 C1-C substituted with dialkylamino, cyano or halogen atoms 12 is alkyl, or A is a divalent aliphatic, cycloaliphatic, aromatic, araliphatic, or heterocyclic organic group; X represents -O- or -NR1-, where R1 is hydrogen or unsubstituted or one or more C1-C 12 Alkoxy groups, C1-C 12 Alkylcarbonyl group, C7-C 25 Arylcarbonyl group, hydroxyl group, amino group, C1-C 12 Alkylamino groups, C1-C 12 C1-C substituted with dialkylamino, cyano or halogen atoms 12 is alkyl, n is 1 or 2, and (C) a protected base in the form of an adduct or salt capable of releasing a basic compound when heated to a temperature above 70°C. The present invention relates to a curable composition comprising: DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Epoxy resins suitable as component (A) are routine in the epoxy resin art. Examples of epoxy resins suitable as component (A) are:

[0012] I) Polyglycidyl and poly(β-methylglycidyl) esters obtainable by reacting a compound having at least two carboxyl groups in the molecule with epichlorohydrin and β-methylepichlorohydrin, respectively, which reaction is preferably carried out in the presence of a base.

[0013] As a compound having at least two carboxyl groups in the molecule, an aliphatic polycarboxylic acid can be used. Examples of such polycarboxylic acids are oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, or dimerized or trimerized linoleic acid.

[0014] However, it is also possible to use cycloaliphatic polycarboxylic acids, such as hexahydrophthalic acid or 4-methylhexahydrophthalic acid.

[0015] Aromatic polycarboxylic acids may also be used, for example phthalic acid, isophthalic acid or terephthalic acid, and partially hydrogenated aromatic polycarboxylic acids, such as tetrahydrophthalic acid or 4-methyltetrahydrophthalic acid.

[0016] II) under alkaline conditions or in the presence of an acid catalyst followed by alkaline treatment, having at least two free alcoholic and / or phenolic hydroxy groups; Polyglycidyl or poly(β-methylglycidyl) ethers obtainable by reaction of the compound with epichlorohydrin or β-methylepichlorohydrin.

[0017] Glycidyl ethers of this kind are, for example, glycidyl ethers of acyclic alcohols, such as ethylene glycol, diethylene glycol or higher poly(oxyethylene) glycols. poly(oxyethylene) glycols, propane-1,2-diol or poly(oxypropylene) glycol, propane-1,3-diol, butane-1,4-diol, poly(oxytetramethylene) glycol, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerol, 1,1,1-trimethylol-propane, pentaerythritol, sorbitol, and also from polyepichlorohydrin.

[0018] Further glycidyl ethers of this type are derived from cycloaliphatic alcohols, such as 1,4-cyclohexanedimethanol, bis(4-hydroxycyclohexyl)methane or 2,2-bis(4-hydroxycyclohexyl)propane, or from alcohols containing aromatic groups and / or further functional groups, such as N,N-bis(2-hydroxyethyl)aniline or p,p'-bis(2-hydroxyethylamino)diphenylmethane. The glycidyl ethers may also be based on mononuclear phenols, such as resorcinol or hydroquinone, or polynuclear phenols, such as bis(4-hydroxyphenyl)methane, 4,4'-dihydroxybiphenyl, bis(4-hydroxyphenyl)sulfone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane or 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane.

[0019] Further hydroxy compounds suitable for the preparation of glycidyl ethers are the novolaks obtainable by condensation of aldehydes, such as formaldehyde, acetaldehyde, chloral or furfuraldehyde, with phenols or bisphenols, unsubstituted or substituted by chlorine atoms or C1-C9 alkyl groups, such as phenol, 4-chlorophenol, 2-methylphenol or 4-tert-butylphenol.

[0020] III) Poly(N-glycidyl) compounds obtainable by dehydrochlorination of the reaction products of epichlorohydrin with amines containing at least two amine hydrogen atoms, such amines being, for example, aniline, n-butylamine, bis(4-aminophenyl)methane, m-xylylenediamine or bis(4-methylaminophenyl)methane.

[0021] However, poly(N-glycidyl) compounds also include triglycidyl isocyanurate, N,N'-diglycidyl derivatives of cycloalkene ureas such as ethylene urea or 1,3-propylene urea, and diglycidyl derivatives of hydantoins such as 5,5-dimethylhydantoin.

[0022] IV) Poly(S-glycidyl) compounds derived from dithiols, such as ethane-1,2-dithiol or bis(4-mercaptomethylphenyl) ether, such as di-S-glycidyl derivatives.

[0023] V) Cycloaliphatic epoxy resins, such as bis(2,3-epoxycyclopentyl) ether, 2,3-epoxycyclopentyl glycidyl ether, 1,2-bis(2,3-epoxycyclopentyloxy)ethane or 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate.

[0024] However, epoxy groups in which the 1,2-epoxy groups are bonded to different heteroatoms or functional groups It is also possible to use resins, such as, for example, N,N,O-triglycidyl derivatives of 4-aminophenol, glycidyl ethers of salicylic acid, N-glycidyl-N'-(2-glycidyloxypropyl)-5,5-dimethylhydantoin and 2-glycidyloxy-1,3-bis(5,5-dimethyl-1-glycidylhydantoin-3-yl)propane.

[0025] The term "cycloaliphatic epoxy resin" in the context of the present disclosure denotes any epoxy resin having cycloaliphatic structural units, i.e. containing both cycloaliphatic glycidyl compounds and β-methylglycidyl compounds, as well as any epoxy resin based on cycloalkylene oxide. "Liquid at room temperature (RT)" should be understood as meaning a pourable compound that is liquid at 25°C, i.e. with low to medium viscosity (viscosity less than about 20000 mPa·s, determined at 25°C by a Rheomat apparatus, type 115; MS DIN 125; D=11 / s).

[0026] Suitable cycloaliphatic glycidyl and β-methylglycidyl compounds are the glycidyl and β-methylglycidyl esters of cycloaliphatic polycarboxylic acids such as tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, and 4-methylhexahydrophthalic acid.

[0027] Further suitable cycloaliphatic epoxy resins are the diglycidyl and β-methylglycidyl ethers of cycloaliphatic alcohols, such as 1,2-dihydroxycyclohexane, 1,3-dihydroxycyclohexane and 1,4-dihydroxycyclohexane, 1,4-cyclohexanedimethanol, 1,1-bis(hydroxymethyl)cyclohex-3-ene, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane and bis(4-hydroxycyclohexyl)sulfone.

[0028] Examples of epoxy resins having a cycloalkylene oxide structure are bis(2,3-epoxycyclopentyl)ether, 2,3-epoxycyclopentyl glycidyl ether, 1,2-bis(2,3-epoxycyclopentyl)ethane, vinylcyclohexene dioxide, 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3',4'-epoxy-6'-methylcyclohexanecarboxylate, bis(3,4-epoxycyclohexylmethyl)adipate and bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate.

[0029] Preferred cycloaliphatic epoxy resins are bis(4-hydroxycyclohexyl)methane diglycidyl ether, 2,2-bis(4-hydroxycyclohexyl)propane diglycidyl ether, tetrahydrophthalic acid diglycidyl ester, 4-methyltetrahydrophthalic acid diglycidyl ester, 4-methylhexahydrophthalic acid diglycidyl ester, 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate, and especially hexahydrophthalic acid diglycidyl ester.

[0030] Aliphatic epoxy resins can also be used as component (A). As "aliphatic epoxy resins", it is possible to use epoxidation products of unsaturated fatty acid esters. It is preferred to use epoxy-containing compounds derived from mono- and poly-fatty acids having 12 to 22 carbon atoms and iodine numbers of 30 to 400, such as lauroleic acid, myristoleic acid, palmitoleic acid, oleic acid, gadoleic acid, erucic acid, ricinoleic acid, linoleic acid, linolenic acid, elaidic acid, licanic acid, arachidonic acid and clupanodonic acid.

[0031] For example, the epoxidation products of the following are suitable: soybean oil, linseed oil, perilla oil, tung oil, oiticica oil, safflower oil, poppy seed oil, hemp oil, cottonseed oil, sunflower oil, rapeseed oil, Polyunsaturated triglycerides, triglycerides derived from Euphorbia plants, peanut oil, olive oil, olive kernel oil, almond oil, kapok oil, hazelnut oil, apricot kernel oil, beech oil, lupine oil, corn oil, sesame oil, grape seed oil, lallemantia oil, castor oil, herring oil, sardine oil, menhaden oil, whale oil, tall oil and derivatives thereof.

[0032] Also suitable are the more highly unsaturated derivatives obtainable by subsequent dehydrogenation of these oils.

[0033] The olefinic double bonds of the unsaturated fatty acid groups of the above-mentioned compounds can be epoxidized according to known methods, for example by reacting with hydrogen peroxide, optionally in the presence of a catalyst, an alkyl hydroperoxide or a peracid, such as performic acid or peracetic acid.Within the scope of the present disclosure, both fully epoxidized oils and partially epoxidized derivatives that still contain free double bonds can be used in component (A).

[0034] Mixtures of the abovementioned epoxy resins I) to V) can also be used. Component (A) preferably comprises an aromatic or alicyclic glycidyl ether or glycidyl ester that is liquid or solid at 25° C., preferably a diglycidyl ether or ester of bisphenol A or bisphenol F. Preferred epoxy resins can also be obtained by reaction of polyglycidyl ethers and polyglycidyl esters with alcohols such as diols. The reaction with diols increases the molecular weight.

[0035] Particularly preferred are epoxy resins that are glycidyl ethers of bisphenol A reacted with less than an equimolar amount of bisphenol A.

[0036] According to a preferred embodiment, the composition according to the invention comprises, as component (A), bisphenol A diglycidyl ether or N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane.

[0037] When an N-glycidyl compound such as N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane is used as component (A), it is not necessary to add a protecting base as component (C) because the N-glycidyl compound is alkaline enough to initiate the curing reaction by deprotonating the cyanoacetic acid derivative. However, by adding component (C) to the above mixture, the curing temperature and time can be significantly reduced without affecting the storage stability.

[0038] Cyanoacetic acid derivatives suitable as component (B) are described, for example, in US Pat. No. 4,283,520, which is incorporated herein by reference.

[0039] Component (B) is represented by the formula A[-X-CO-CH2-CN] n (1) The compound may be:

[0040] A in formula (1) as a monovalent group can be, for example, hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, isooctyl, benzyl, 3-(dimethylamino)propyl, 3-(diethylamino)propyl, di-n-butylamino, N-molino, or phenylamino.

[0041] A in formula (1) as a divalent group is, for example, ethylene, propylene, tetramethylene, hexamethylene, 2,2-dimethylpropanediyl, 1,3-cyclohexylene, 1,4- Cyclohexylene, 1,3-cyclohexylenedimethylene, 1,4-cyclohexylenedimethylene, m-phenylene, p-phenylene, or a group of the formula: [ka] It can be.

[0042] A is 3-dimethylaminopropyl, hexamethylene, cyclohexane-1,3-diyl, m-phenylene or a compound of the formula [ka] Compounds of formula (1) representing the group

[0043] Component (C) is a "protected base". The term "protected base" as used herein refers to any salt or adduct of a basic or nucleophilic compound that can react with the oxirane ring of the epoxide (A) by deprotonating the cyanoacetic acid derivative, thereby initiating the curing reaction. The starting compounds for preparing component (C) can be, for example, aliphatic, araliphatic, aromatic or heterocyclic amines, guanidines and N-heterocyclic compounds that exhibit a pKa value of the conjugate acid greater than 7.5 (in acetonitrile), preferably greater than 8.0, more preferably greater than 8.5, in particular greater than 9.5, and can be reversibly blocked by the addition of a Bronsted or Lewis acid or an epoxide.

[0044] It is essential that upon heating to a temperature above 70°C, preferably above 85°C, and more preferably above 100°C, the shutoff is reversed and the cyanoacetic acid derivative is deprotonated, thereby releasing a compound that is basic enough to react with the oxirane ring of the epoxide molecule and initiate the curing reaction.

[0045] Examples of such compounds are aliphatic amines such as ethylamine or dimethyloctylamine, urones such as N'-(4-chlorophenyl)-N,N-dimethylurea and N'-(3,4-dichlorophenyl)-N,N-dimethylurea, guanidines such as dicyandiamide and didyandiamide / imidazoline salts, imidazoles such as 1-methylimidazole and 1-methyl-3-ethylimidazole, and amidines such as 1,8-diazabicycloundec-7-ene (DBU).

[0046] Further examples of compounds which can be used as component (C) are alkali alkoxides and alkali phenolates.

[0047] In a preferred embodiment, the hardenable composition comprises as component (C) a urea derivative, or an adduct or salt of an imidazole or amidine derivative.

[0048] An adduct or salt of 1-methyl-3-ethylimidazole, 1,8-diazabicycloundec-7-ene (DBU) or 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) is particularly preferred as component (C).

[0049] The blocking agents which reduce the alkalinity of the organic nitrogen-containing compounds and release it again at temperatures above 70° C. are Bronsted or Lewis acids or epoxides.

[0050] Examples of Bronsted acids suitable as blocking agents are phenols such as phenol, o-, m- and p-cresol, bisphenol A and bisphenol F, and carboxylic acids such as acetic acid, 2-ethylhexanoic acid, salicylic acid, trimellitic acid and ethylenediaminetetraacetic acid (EDTA).

[0051] Instead of the free acids, the corresponding anhydrides can also be applied, for example trimellitic anhydride.

[0052] Suitable Lewis acids such as boron trihalides, preferably BF3 and BCl3, can be used.

[0053] Preferably, the curable composition according to the present disclosure comprises as component (C) a phenol salt, a carboxylate salt, an epoxide adduct, or a boron trihalide adduct of an organic nitrogen-containing compound.

[0054] Particularly preferred are curable compositions which contain as component (C) salts of acetic acid, 2-ethylhexanoic acid, ethylenediaminetetraacetic acid, salicylic acid, trimellitic acid, or boron trifluoride or boron trichloride adducts.

[0055] Furthermore, curable compositions comprising as component (C) a urea derivative or an adduct or salt of an imidazole or amidine derivative are preferred.

[0056] More preferably, the curable composition according to the invention comprises as component (C) an adduct or salt of 1-methyl-3-ethylimidazole or 1,8-diazabicycloundec-7-ene.

[0057] Examples of suitable components (C) are: imidazole salts such as 1-methylimidazole / acetic acid, 1-methylimidazole / 2-ethylhexanoic acid, and 1H-imidazolium with N-cyanocyanamide, 3-ethyl-1-methyl-, salts (1:1); amidine salts such as DBU / phenol, DBU / m-cresol, DBU / o-cresol, DBU / p-cresol, DBU / acetic acid, DBU / trifluoroacetic acid, DBU / 2-ethylhexanoic acid, DBU / EDTA, and DBU / trimellitic acid; and amidine / boron trihalide adducts such as DBU / BF3.

[0058] Particularly preferred components (C) are DBU / phenol, DBU / acetic acid, DBU / BF3, and 1H-imidazolium, 3-ethyl-1-methyl-, salt with N-cyanocyanamide (1:1).

[0059] Components (A) and (B) are preferably present in approximately equivalent amounts, i.e., in the amount of about 100% by weight of the acidic methylene hydrogen atoms and active hydrogen atoms bonded to the amino nitrogen atoms of the compound of formula (1) and the reactive epoxy groups. However, it is possible to use more or less than an equivalent amount of epoxy component or hardener. The amount used will depend on the desired final properties of the reaction product, as known to those skilled in the art.

[0060] Preferably, the curable composition according to the present disclosure contains components (A) and (B) such that the amount of -CO-CH2-CN groups is 0.1 to 1.0 mol, more preferably 0.2 to 0.8 mol, more preferably 0.25 to 0.45 mol per mol of epoxy groups.

[0061] The amount of component (C) in the curable composition is preferably 0.001 to 0.1 mol, more preferably 0.005 to 0.05 mol, and more preferably 0.01 to 0.04 mol, per 1 mol of epoxy groups.

[0062] The compositions according to the present disclosure may be prepared by mixing the individual components at room temperature or slightly elevated temperature, if necessary using a suitable mill, such as a ball or pin mill, kneader or mixer.

[0063] The mixture has exceptional storage stability, i.e., no significant chemical reaction between the components occurs at room temperature. Storage at low temperatures is not necessary.

[0064] The curable compositions may contain fillers, adjuvants and additives common in the epoxy resin art.

[0065] Possible fillers are, for example: metal powders, wood flour, glass powder, glass granules, SiO2 (quartz sand, quartz sand powder, silanized quartz sand powder, synthetic quartz sand powder, silanized synthetic quartz sand powder), metalloid and metal oxides such as aluminum oxide, titanium oxide and zirconium oxide, metal hydroxides such as Mg(OH)2, Al(OH)3, silanized Al(OH)3 and AlO(OH), metalloid and metal carbides (SiC and boron carbide), metal carbonates (dolomite, chalk, CaCO3), metal sulfides (barite, gypsum), rock powders from hydromagnesium and huntite, as well as natural or synthetic minerals from silicate rows such as zeolites (especially molecular sieves), talc, mica, kaloin, wollastonite, and others.

[0066] In addition to the fillers mentioned above, the curable mixture may contain antioxidants, e.g., sterically hindered phenols, flame retardants, fillers containing water of crystallization, diluents, colorants, pigments, fungicides, thixotropic agents and the like. and the usual adjuvants and additives such as hydrophobic agents, thickeners, antifoaming agents, antistatic agents, lubricants, suspending agents, wetting agents, softening agents, diluents and release agents.

[0067] The curable compositions of the present invention may optionally further comprise inorganic and / or organic additives selected from, for example, flow control additives, antifoaming agents, anti-sag agents, pigments, reinforcing agents, fillers, elastomers, stabilizers, extenders, plasticizers, flame retardants, accelerators, colorants, fibrous materials, thixotropic agents, anticorrosive pigments and solvents.

[0068] A preferred embodiment of the composition disclosed herein is the so-called 1.5K system, where components (A) and (B) are mixed in appropriate amounts and stored at room temperature. Just before application, component (C) is added. This allows for an extremely long pot life combined with very rapid curing at the target temperature.

[0069] By selecting an appropriate component (C), the pot life can be varied over a very wide range, from about 30 minutes to more than 4 months.

[0070] The compositions disclosed herein can be cured by known methods, typically by heating the mixture at a temperature of 70°C to 250°C, preferably 100°C to 180°C.

[0071] A further object of the present invention is the crosslinked products obtainable by curing the disclosed compositions.

[0072] The epoxy resin compositions and cured materials described herein can be used, for example, as coatings, adhesives, floor coverings, casting resins, tooling resins, impregnating resins, or encapsulating resins.

[0073] Preferably, the compositions of the present invention are used in the manufacture of adhesives, coatings or composite materials.

[0074] The following examples serve to illustrate the compositions disclosed herein, in which "parts" are parts by weight and "percentages" are percent by weight, unless otherwise indicated. EXAMPLES

[0075] Example 1: Bis(cyanoacetylaminomethyl)tricyclo[5.2.1.0 2,6 Synthesis of one-component mixture of decane + bisphenol A diglycidyl ether In a glass reactor (500 ml), bis(aminomethyl)-tricyclo[5.2.1.0 2,6 ]decane (50 g, 0.26 mol). Ethyl cyanoacetate (61.12 g, 0.54 mol, 2.1 eq) is added slowly to the stirred solution over 30 min, taking care that the internal temperature never rises above 50° C. The mixture is stirred at room temperature (RT) for 1 h. A vacuum (approximately 80 mbar) is then applied to remove the ethanol formed and the temperature is slowly raised to 80° C. over 30 min. The mixture is stirred at 80° C. for a further 2 h. To ensure complete conversion, the mixture is then heated to 100° C., still under vacuum, for 1 h. The amount of ethanol collected in the liquid nitrogen trap is measured. The mixture is allowed to cool to 80° C. and the vacuum is released. 294 g of Araldite® GY 250 resin (bisphenol-A-diglycidyl ether from Huntsman Advanced Materials with an average epoxy equivalent weight of 187) is added and the mixture is held under vacuum at 80° C. for 30 minutes, then cooled to 60° C. and deloaded from the reactor. Final mixed viscosity of the mixture at 50°C = 2.5 Pas

[0076] Example 2: Bis(cyanoacetylaminomethyl)tricyclo[5.2.1.0 2,6 Synthesis of a one-liquid mixture of decane + N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane In a glass reactor (500 ml), bis(aminomethyl)-tricyclo[5.2.1.0 2,6]decane (50 g, 0.26 mol). Ethyl cyanoacetate (61.12 g, 0.54 mol, 2.1 eq) is added slowly to the stirred solution over 30 minutes, taking care that the internal temperature never rises above 50° C. The mixture is stirred at room temperature for 1 hour. A vacuum (about 80 mbar) is then applied to remove the ethanol formed and the temperature is slowly raised to 80° C. over 30 minutes. The mixture is stirred at 80° C. for 2 hours. To ensure complete conversion, the mixture is then heated to 100° C., still under vacuum, for 1 hour. The amount of ethanol collected in the liquid nitrogen trap is measured. The mixture is allowed to cool to 80° C. and the vacuum is released. Resin (179 g of MY 721 resin from Huntsman Advanced Materials with an average epoxy equivalent weight of 114) is added and the mixture is kept under vacuum at 80° C. for 30 minutes, then cooled to 60° C. and unloaded from the reactor. Final mixed viscosity of the mixture at 80°C = 2.3 Pas

[0077] Example 3: Synthesis of DBU / Acetate A round bottom flask is charged with acetic acid (6 g, 0.1 mol), THF (40 ml) and a stir bar and cooled in an ice bath. 1,8-diazabicycloundec-7-ene (DBU) (15.2 g, 0.1 mol) is added dropwise via syringe to the stirring solution. The mixture is stirred at room temperature for 2 hours and the THF is evaporated on a rotavapor to give the compound as a viscous oil.

[0078] Example 4: Synthesis of DBU / BF3 salt A round-bottom flask is charged with DBU (15.2 g, 0.1 mol), THF (40 ml), and a magnetic stir bar and cooled in an ice bath. BF3-etherate (14.2 g, 0.1 mol) is added dropwise via syringe to the stirring solution. The mixture is stirred at room temperature for 2 h and the THF is evaporated on a rotavapor to give the compound as a white solid.

[0079] Example 5: Hardening of 1K Mixtures with DBU / Acetate The one-part mixture of Example 1 (about 10 g) is heated in a glass reactor at 40° C. and the DBU / acetate of Example 3 (0.173 g, about 2 mol % relative to the number of epoxy groups) is added. The mixture is stirred under vacuum at 40° C. for 15 minutes and then poured into a mold. The mold is heated according to the following curing schedule: 110° C. for 30 minutes + 140° C. for 30 minutes and 170° C. for 10 minutes to obtain a hard material with a glass transition temperature of about 155° C.

[0080] Example 6: Hardening of 1K mixtures with DBU / BF3 salt The one-part mixture of Example 1 (about 10 g) is heated in a glass reactor at 40° C. and the DBU / BF3 salt of Example 4 (0.18 g, about 2 mol % based on the moles of epoxy groups) is added. The mixture is stirred under vacuum at 40° C. for 15 minutes and then poured into a mold. The mold is heated according to the following curing schedule: 1 h / 80° C., 1 h / 140° C., 1 h / 170° C. to obtain a hard material with a glass transition temperature of about 165° C.

[0081] Example 7: Curing of 1K mixtures using imidazole adduct protected bases The one-part mixture of Example 1 (10 g) is heated in a glass reactor at 40° C. and the commercial Aradur® 3123 hardener, 1-((2-methyl-1H-imidazol-1-yl)methyl)naphthalen-2-ol, CAS number: 185554-99-8 (0.19 g, 2 mol % based on the number of epoxy groups) is added. The mixture is stirred under vacuum at 40° C. for 15 minutes and then poured into a mold. The mold is heated according to the following curing schedule: 110° C. for 30 minutes + 140° C. for 30 minutes and 170° C. for 10 minutes to obtain a hard material with a glass transition temperature of about 170° C.

[0082] Example 8: Hardening of 1K mixtures using asymmetric urea protected bases The one-part mixture of Example 1 (10 g) is heated in a glass reactor at 40° C. and commercially available 1,1-(4-methyl-m-phenylene)bis(3,3″-dimethylurea) (Dyhard UR 500, Alzchem), CAS number: 17526-94-2 (0.216 g, 2 mol % based on the number of epoxy groups) is added. The mixture is stirred under vacuum at 40° C. for 15 minutes and then poured into a mold. The mold is heated according to the following curing schedule: 110° C. for 30 minutes + 140° C. for 30 minutes and 170° C. for 10 minutes to obtain a hard material with a glass transition temperature of about 150° C.

[0083] Example 9: Hardening of 1K mixtures using polymeric salts The one-part mixture of Example 1 (approximately 8.3 g) is heated in a glass reactor at 40° C. and commercial Aradur® 1167 hardener (0.17 g, 2 wt %) is added. The mixture is stirred under vacuum at 40° C. for 15 minutes and then poured into molds. The molds are cured according to the following curing schedule: Heating is then performed: 110°C for 30 minutes + 140°C for 30 minutes and 170°C for 10 minutes to obtain a hard material with a glass transition temperature of about 120°C.

[0084] Comparative Example 1: Hardening of 1K Mixtures with DBU as the Unprotected Base As described in Example 5, the one-part mixture of Example 1 (50 g) is heated in a glass reactor at 40° C. and DBU of Example 3 (0.63 g, approximately 2 mol % based on the number of epoxy groups) is added. The mixture is stirred under vacuum at 40° C. for 15 minutes and then poured into a mold. The mold is heated according to the following cure schedule: 110° C. for 30 minutes + 140° C. for 30 minutes and 170° C. for 10 minutes. A hard material is obtained with a glass transition temperature of about 150°C.

[0085] The pot life and glass transition temperatures of the cured products of Examples 5-7 are summarized in Table 1: [Table 1] *Cure schedule for all samples except DBU-BF3 catalyst: 110°C for 30 minutes + 140°C for 30 minutes and 170°C for 10 minutes. ** Pot life is defined as the time it takes for the viscosity of the system to double at 23°C. *** Measured by DSC (scan rate 10°C / min) at the midpoint of the transition temperature. All catalysts are used at a loading of 2 mol % based on moles of epoxy groups, except for Example 9 which was used at 2 wt %.

Claims

1. Epoxy resins containing an average of more than one epoxy group per molecule; formula 4[-X-CO-CH ２ --N] ｎ (1) (Wherein, A is hydrogen or unsubstituted or one or more C １ -C １２ Alkoxy group, C １ -C １２ Alkylcarbonyl group, C ７ -C ２５ Arylcarbonyl group, hydroxyl group, amino group, C １ -C １２ Alkylamino group, C １ -C １２ C substituted with a dialkylamino group, a cyano group or a halogen atom １ -C １２ is alkyl, or A is a divalent aliphatic, cycloaliphatic, aromatic, araliphatic, or heterocyclic organic group; X is -O- or -NR １ -, where R １ is hydrogen, or unsubstituted or one or more C １ -C １２ Alkoxy group, C １ -C １２ Alkylcarbonyl group, C ７ -C ２５ Arylcarbonyl group, hydroxyl group, amino group, C １ -C １２ Alkylamino group, C １ -C １２ C substituted with a dialkylamino group, a cyano group or a halogen atom １ -C １２ is alkyl, n is 1 to 4; and A protected base in the form of an adduct or salt capable of releasing a basic compound when heated to a temperature above 70° C.

1. A curable composition comprising:

2. 2. The curable composition of claim 1, comprising as component (A) bisphenol A diglycidyl ether or N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane.

3. As the component (B), a compound represented by the formula (1) (wherein A is 3-dimethylaminopropyl, cyclohexane-1,3-diyl, m-phenylene or the formula 【Chemistry 1】 The curable composition according to claim 1 or 2, comprising a compound of formula (I)

4. The curable composition according to any one of claims 1 to 3, comprising as component (C) a phenol salt, a carboxylate salt, an epoxide adduct or a boron trihalide adduct of an organic nitrogen-containing compound.

5. Component (C) is selected from the group consisting of acetic acid, 2-ethylhexanoic acid, ethylenediaminetetraacetic acid, salicylic acid, trimellitic acid, and a salt of trimellitic anhydride, and BF ３ The curable composition of claim 4 comprising an adduct.

6. 6. The curable composition according to claim 1, comprising as component (C) a urea derivative or an adduct or salt of an imidazole or amidine derivative.

7. 7. The curable composition of claim 6, comprising as component (C) an adduct or salt of 1-methylimidazole, 1,8-diazabicycloundec-7-ene (DBU) or 1,5-diazabicyclo[4.3.0]non-5-ene (DBN).

8. Components (A) and (B) are mixed together in an amount of 0.1 mol to 10 mol of -C per 1 mol of epoxy group. O-CH ２ A curable composition according to any one of claims 1 to 7, comprising -CN groups in such an amount that they are present.

9. The curable composition according to any one of claims 1 to 8, comprising component (C) in an amount of 0.001 mol to 0.1 mol per 1 mol of epoxy groups.

10. A method for producing a cured article comprising heating the composition of claim 1 to a temperature of from 100°C to 250°C.

11. 10. Use of the composition according to claim 1 for the production of adhesives, coatings, casting materials or composite materials.

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