Method of hardening epoxy resins

Filled moulding masses which can be stored and are hardenable by pressure and heat, comprise a polyepoxide and a hardener therefore which is a liquid aromatic amine having at least two primary amino groups and at least two alkyl groups which are bound to the aromatic nucleus, the amino groups each being in the ortho position to at least one alkyl group. Specified amines are 1,3-diethyl-4,6-diaminobenzene; 1,3 - diethyl - 2,6 - diaminobenzene; 1,3,5 - triethyl - 2,4 - diaminobenzene; 1-methyl - 3,5 - diethyl - 2,4 - diaminobenzene; 1 - ethyl - 3,5 - di - isopropyl - 2,4 - diaminobenzene; 1 - isopropyl - 3,5 - dibutyl - 2,4 - diaminobenzene; 3,31,5,51 - tetraethylbenzidine and liquid mixtures of such amines with solid aromatic amines, e.g. commercial mixtures of 1 - methyl - 3,5 - diethyl - 2,4 - diaminobenzene with 1 - methyl - 3,5 - diethyl - 2,6 - diaminobenzene, m-phenylenediamine and 4,41-diaminodiphenylmethane. The mixture of polyepoxide and hardener is mixed with a pulverulent, granular or fibrous filler or used to impregnate fibrous structures possibly in conjunction with a filler of small particle size. Pre-condensation to a friable, fusible and curable mass takes place on standing at room temperature or on heating for a short time. Curing takes place on heating to 150-180 DEG C. using pressures of 1.5-20 kg./cm2. The moulding masses may be used as moulding powders and in the manufacture of laminates.