A process and a compsn. are claimed for coating a material, particularly sand, which can then be moulded and catalytically hardened, the compsn, comprising a polyisocyanate, a polyhydroxy cpd. and opt. a solvent. The improvement consists in the polyhydroxy cpd. comprising 5-100 wt % polyols contg. 2-6, pref. 2-3 terminal or side gps. of formula (I)-(IV): (where R1 and R2 are H or CH3). The use of above polyols results in the coating compsn. being as reactive as those based on phenols without the attendant drawback of pollution caused by presence of phenol. The moulding compsn. has good heat shock resistance and can be readily disintegrated after moulding the metals (e.g. iron, steel or light metals).
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