Alkali metal silicate binder compositions
First Claim
1. In a binder composition obtained by mixing, in aqueous solution, an alkali metal silicate and a hydrogenated starch hydrolysate, the improvement comprising including urea in said composition.
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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 metal silicate
(ii) a substantially water soluble carbohydrate selected from monosaccharides, disaccharides, polysaccharides and derivatives thereof and
(iii) urea.
The composition may also contain an oxyanion such as a borate which is capable of forming a water soluble complex with the carbohydrate. The preferred carbohydrate is a stabilized starch hydrolysate whose reducing power has been removed by a process such as hydrogenation.
Moulds and cores bonded using the composition may be hardened by injection of carbon dioxide gas, or a chemical hardening agent for the alkali metal silicate may be added to the sand.
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Citations
18 Claims
- 1. In a binder composition obtained by mixing, in aqueous solution, an alkali metal silicate and a hydrogenated starch hydrolysate, the improvement comprising including urea in said composition.
- 8. In a binder composition obtained by mixing, in aqueous solution, an alkali metal silicate, a substantially water soluble carbohydrate selected from monosaccharides, disaccharides, polysaccharides and derivatives thereof and an oxyanion salt, the improvement comprising including urea in said composition.
Specification