Alkali metal silicate binder compositions

Abstract

A binder composition in aqueous solution, suitable for use in the production of foundry sand moulds and cores is obtained by mixing (i) an alkali silicate (ii) a substantially water soluble carbohydrate selected from monosaccharides, disaccharides, polysaccharides and derivatives thereof and (iii) a phenolic compound selected from monohydric phenols, dihydric phenols, trihydric phenols, phenols of polynuclear hydrocarbons and phenolic acids, which is miscible with or soluble in an aqueous solution of an alkali metal silicate. The composition may also contain an oxyanion such as a borate which is capable of forming a water soluble complex with the carbohydrate. A mixture of phenolic compounds, such as a mixture consisting predominantly of isomers of di- and trihydroxy diphenyl obtained in the distillation of crude resorcinol, may be used. The preferred carbohydrate is a stabilized starch hydrolysate whose reducing power has been removed by a process such as hydrogenation.

Dependencies are inferred from the claim text.