MODIFYING ADDITIVE

摘要

A modifying additive of the invention relates to foundry, in particular, to compositions of modifying additives for clay binders and can be used for preparing molding sand and mixtures in foundry engineering and other similar technological processes affecting structural mechanical properties of clay materials. The inventive task is aimed at developing an additive composition to completely cancelling dependence of its modifying effect from a phenol feedstock composition taking part in a reaction of condensation with formaldehyde in acidic medium for producing a main component - novolak with simultaneous providing the required properties. The technical task is characterized in that a triannulate sulfomethylated novolak is used as novolak in the modifying additive, said triannulate sulfomethylated novolak is a product of reaction of condensation using biatomic phenol - pyrocatachin as the phenol feedstock with the ratio of reagents 3:2 and the following component ratio, (wt%): sodium salt of triannulate sulfomethylated novolak - 35-45, water - remaining. When using the additive while preparing moulding sand for fabricating formworks of advanced complexity, e.g. with deep “pockets” the modifying additive further comprises polyethylene glycol in an amount of 0.1-0.5 of wt %. The technical result provides an average increase of the process properties by 22-25%.