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—CH2—CN]n (1),
• wherein A is hydrogen or C1-C12 alkyl which is unsubstituted or substituted by one or more C1-C12 alkoxy groups, C1-C12 alkylcarbonyl groups, C7-C25 arylcarbonyl groups, hydroxyl groups, amino groups, C1-C12 alkylamino groups, dialkylamino groups with C1-C12 alkyls, cyano groups or halogen atoms or
• A is a bivalent aliphatic, cycloaliphatic, aromatic, araliphatic or heterocyclic organic radical, X denotes —O— or —NR1— wherein R1 is hydrogen or a C1-C12 alkyl which is unsubstituted or substituted by one or more C1-C12 alkoxy groups, C1-C12 alkylcarbonyl groups, C7-C25 arylcarbonyl groups, hydroxyl groups, amino groups, C1-C12 alkylamino groups, dialkylamino groups with C1-C12 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).