| 摘要 |
A composition of sand with 1,75 to 3,5% of its weight of a thermosetting resinous composition is used. This resinous material is a solution, in an aqueous milk of an alkaline earth base, of a novolak resin, and has the property that, on treatment with carbonic acid, CO2 or SO2, the resin is precipitated. This precipitation of resin binds the sand together, and the binding can be further strengthened by heating in a stove, 4-12% by weight of a curing agent, e.g. hexamethylenetetramine having been incorporated in the original mixture. Further fillers, &c., e.g. dextrin, chalk, may be added to the original mixture. Specification 899,776 is referred to. |
