| 摘要 |
<p>A foundry moulding composition comprising (a) a granular refractory material, (b) from 0.25 to 2.5% based on the weight of the refractory material of an aqueous solution of a potassium alkali phenol-formaldehyde resin, said aqueous solution having a solids content of from 50 to 75% and said resin having a weight average molecular weight ( &upbar& Mwr) of from 700 to 2000, a formaldehyde:phenol molar ratio of from 1.2:1 to 2.6:1 and a potassium hydroxide:phenol molar ratio of from 0.5:1 to 1.2:1; (c) from 0.05 to 3% based on the weight of said aqueous solution, of at least one silane, and (d) from 20 to 110% based on the weight of said aqueous solution of at least one ester active to catalyze curing of said resin.</p> |
