1,190,644. Phenolic resin compositions. ASHLAND OIL & REFINING CO. 31 July, 1967 [1 Aug., 1966; 2 May, 1967], No. 35167/67. Heading C3R. A binder composition, particularly for founddry cores, comprises a solution of a non-aqueous phenolic resin in an organic solvent, a polyisocyanate in liquid form as hardener and a tertiary amine as catalyst. In practice, the resin solution and polyisocyanate are mixed with the aggregate, e.g. sand, the mixture is moulded, and the amine is passed through the moulded shape. The phenolic resins can be resole, A-stage or novolac resins, the latter being preferred. The polyisocyanate may be aliphatic, cycloaliphatic or aromatic and may be a prepolymer of excess polyisocyanate with a polyhydric alcohol. Solid or viscous isocyanates are employed as organic solvent solutions. Specified tertiary amines are trimethyl and triethyl amines and dimethyl ethanolamine. They may be used as such or diluted in an inert gas. The binder usually constitutes less than 10% of the foundry mix, and other additives may be included, e.g. alkoxysilanes, iron oxide, ground flax fibres, wood cereals, pitch and refractory flows.
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