Casting mould sand contg. polyester resin - as lustrous carbon former, in addition to bentonite and water

摘要

Bentonite- and water-contg. casting mould sand also contains 0.5-3 wt.% granulated, fibrous or ground polyester resin as lustrous C former. Pref. polyester resin undergoes pyrolytic decompsn. at =300 (500-600) degrees C. Scorching of moulding sand is prevented without forming smell and smoke. The polyesters do not absorb water and the wet breaking strength is not affected.