Patent ID: 7022178

Claim:
A binding agent for a core sand mixture used in foundry processes, comprising: (a) a binder incorporating an aqueous alkali silicate solution containing 1. an alkali silicate having the formula xSiO 2 ·yM 2 O·zH 2 O wherein M is Li + , K + , or Na + ; and 2. a hygroscopic base, sodium hydroxide, in the ratio of one part of the base per 4 to 6 parts of the alkali silicate; wherein the ratio of Na 2 O/SiO 2 is 2.5 to 3.5 and the solids content is 20 to 40% of the solution; and, in admixture therewith; (b) an emulsion containing a silicone oil having a boiling point of ≧250° in an amount of from 8 to 10% of the binder.