Rapidly-curing novolak resin compsns. contain (I) hexamethylenetetramine, (II) 0.5-2.5 x their wt. of filler, and (III) 1-15 % wt., pref. 2-8% wt. boric acid (based on resin), pref. in half to equimolar ratio with the hexamethylenetetramine. The novolak resin compsns. contng. boric acid are characterised by curing very rapidly enabling uniformly cured mouldings of thick section to be prepd. The compsns. are suitable fo ruse in automatic moulding machines, including injection moulding machines. The cured resins have high thermal resistance.
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