Process for preparing foundry cores or molds and binder materials used therefor

A process for preparing a foundry core or mold which comprises forming into a shape of a core or mold a foundry mold composition containing (A) refractory particles, and (B) a foundry binder material comprising an alcohol-soluble phenolic resin selected from the group consisting of a resole, a novolac, an N-methylene-resole, a dimethylene ether-type resole, a formal-type resole and a mixture thereof, 10 to 300 parts by weight of a hydroxide and/or an oxide of a polyvalent metal selected from the group consisting of an alkaline earth metal, aluminum, zinc, iron, nickel, titanium, silicon, tin, and a mixture thereof, 100-500 parts by weight of water, 1 to 100 parts by weight of an organic solvent selected from the group consisting of an alcohol, an aromatic hydrocarbon, a ketone, an acetic ester, a phthalic ester, an ether, a cellosolve, dimethylformamide dimethyl sulfoxide and a mixture thereof, and 0.1 to 50 parts by weight of an alkali metal hydroxide, said parts by weight being based on 100 parts by weight of said alcohol-soluble phenolic resin, and then gassing said core or mold with carbon dioxide.