Latent curing accelerators
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—CH 2 —CN] n (1), wherein A is hydrogen or C 1 -C 12 alkyl which is unsubstituted or substituted by one or more C 1 -C 12 alkoxy groups, C 1 -C 12 alkylcarbonyl groups, C 7 -C 25 arylcarbonyl groups, hydroxyl groups, amino groups, C 1 -C 12 alkylamino groups, C 1 -C 12 dialkylamino groups, cyano groups or halogen atoms, or A is a bivalent aliphatic, cycloaliphatic, aromatic, araliphatic or heterocyclic organic radical, X denotes —O—or —NR 1 —, wherein R 1 is hydrogen or C 1 -C 12 alkyl which is unsubstituted or substituted by one or more C 1 -C 12 alkoxy groups, C 1 -C 12 alkylcarbonyl groups, C 7 -C 25 arylcarbonyl groups, hydroxyl groups, amino groups, C 1 -C 12 alkylamino groups, C 1 -C 12 dialkylamino groups, cyano groups or halogen atoms, n is 1 or 2; 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., is storage-stable, allows processing over a longer period of time (pot-life) and produces cured products having outstanding mechanical and thermal properties.
1. 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—CH 2 —CN] n (1),
wherein A is hydrogen or C 1 -C 12 alkyl which is unsubstituted or substituted by one or more C 1 -C 12 alkoxy groups, C 1 -C 12 alkylcarbonyl groups, C 7 -C 25 arylcarbonyl groups, hydroxyl groups, amino groups, C 1 -C 12 alkylamino groups, dialkylamino groups with C 1 -C 12 alkyls, cyano groups or halogen atoms or
A is a bivalent aliphatic, cycloaliphatic, aromatic, araliphatic or heterocyclic organic radical, X denotes —O— or —NR 1 — wherein R 1 is hydrogen or a C 1 -C 12 alkyl which is unsubstituted or substituted by one or more C 1 -C 12 alkoxy groups, C 1 -C 12 alkylcarbonyl groups, C 7 -C 25 arylcarbonyl groups, hydroxyl groups, amino groups, C 1 -C 12 alkylamino groups, dialkylamino groups with C 1 -C 12 alkyls, cyano groups or halogen atoms, and
n is 1 or 2; 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. wherein the protected base is selected from at least one of (i) a bronsted acid salt, a carboxylic acid salt, an epoxide adduct or a boron trihalide adduct of an aliphatic amine wherein the bronsted acid is selected from phenol, o-cresol, m-cresol, p-cresol, bisphenol A and bisphenol F, (ii) a phenol salt, a carboxylic acid salt, an epoxide adduct or a boron trihalide adduct of dicyandiamide, (iii) a bronsted acid salt, an epoxide adduct or a boron trihalide adduct of an imidazole wherein the bronsted acid is selected from phenol, o-cresol, m-cresol, p-cresol, bisphenol A and bisphenol F, (iv) a carboxylic acid salt, an epoxide adduct or a boron trihalide adduct of 1,8-diazabicycloundec-7-ene wherein the carboxylic acid salt is selected from the group consisting of an acetic acid salt, an ethylenediaminetetraacetic acid salt and a salicylic acid salt, (v) a phenol salt, a carboxylic acid salt, an epoxide adduct or a boron trihalide adduct of 1,5-diazabicyclo [4.3.0] non-5-ene, (vi) a phenol salt, a carboxylic acid salt, an epoxide adduct or a boron trihalide adduct of N′-(4-chlorophenyl)-N,N-dimethylurea or N′-(3,4-dichlorophenyl)-N,N-dimethylurea, and (vii) a 1H-imidazolium,3-ethyl-1-methyl-, salt with N-cyanocyanamide(1:1).
2. The curable composition according to claim 1 comprising as component (A) a bisphenol A diglycidylether or N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane.
3. The curable composition according to claim 1 comprising as component (B) a compound of formula (1), wherein A represents 3-dimethylaminopropyl, cyclohexane-1,3-diyl, m-phenylene or a group of the formulae
4. The curable composition according to claim 1 containing components (A) and (B) in such amounts that 0.1 mol to 10 mol —CO—CH 2 —CN groups are present per mol epoxy groups.
5. The curable composition according to claim 1 containing component (C) in an amount of 0.001 mol to 0.1 mol per mol epoxy groups.
6. A process for the preparation of a cured article which comprises heating the composition according to claim 1 to a temperature of 100° C. to 250° C.
7. An adhesive comprising the composition of claim 1 .
8. A coating comprising the composition of claim 1 .
9. A casting comprising the composition of claim 1 .
10. A composite material comprising the composition of claim 1 .