Foundry moulding sand contg. phenol!-formaldehyde! resin binder - and partially alkylated phenol!-formaldehyde! novolak resins to improve heat distortion properties

摘要

A foundry compsn. comprises sand, 1-10 wt.% (on wt. of sand) of a phenol-HCHO resin to bind the sand particles and an additive to improve heat distortion properties comprising ortho alkyl, para alkyl and/or ortho and para dialkyl substd. phenol-HCHO novolak resins. The latter resins are partially alkylated with 1-22C alkyl,3-22C alkene, 8-12C alkylbenzene and/or 6-20C (un)satd. alicyclic gps. The additive imparts improved plasticity and heat distortion temps. to foundry cores and moulds for use in shell moulding and in hot box no bake, cold box processes. Reduced emission of smoke and odour is achieved.