| 摘要 |
A process of coating sand with a phenolformaldehyde resin to produce a shell sand for use in shell molds and cores. The process comprises the steps of reacting phenol and formaldehyde at an elevated temperature to produce hot liquid phenolformaldehyde resin as a reaction product, transferring the hot liquid phenolformaldehyde resin to a mixing station while maintaining the resin at an elevated temperature to prevent solidification of the hot reaction product, mixing the hot liquid phenolformaldehyde resin with preheated sand at the mixing station to coat the sand with the resin, and cooling the coated sand to solidify the resin. When the phenol and formaldehyde are reacted at a location remote from the mixing station, the hot liquid phenolformaldehyde resin is transferred from the reaction station to the mixing station in insulated containers. The liquid resin is preferably maintained at a temperature of at least 250 DEG F. until it is mixed with the preheated sand. The process yields a superior shell sand for forming shell molds or shell cores.
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