BINDER BASED ON POLYURETHANE FOR PRODUCING CORES AND MOULDS USING ISOCYANATES CONTAINING A URETHONIMINE AND/OR CARBODIIMIDE GROUP, A MOULD MATERIAL MIXTURE CONTAINING SAID BINDER, AND A METHOD FOR USING SAID BINDER

Binder for molding mixtures, comprises (A) one or more polyol compounds having at least 2 hydroxy groups per molecule containing at least one phenolic resin as a polyol compound and (B) one or more isocyanate compounds having at least 2 isocyanate groups per molecule containing at least one isocyanate compound having at least 2 isocyanate groups per molecule further comprising at least one urethonimine group and/or carbodiimide group per molecule. Independent claims are included for: (1) a molding mixture comprising the binder and refractory molding materials; and (2) producing a shaped body as mold part or as a core comprising (i) mixing the refractory molding materials with the binder (0.2-5 (preferably 0.4-3) wt.%) to obtain a molding material mixture, introducing the molding material mixture or its components into a mold, curing the molding material mixture in the mold to obtain a self-supporting form, and separating the cured molding from the mold and optionally further curing to obtain a cured molded article.