Method of preparing resin coated foundry sand using unsaturated polyester

摘要

In preparing a resin coated sand for use in sand mold casting processes by a hot-melt process using an unsaturated polyester which is solid at room temperature as the coating material, a solution of an organic peroxide as a polymerization initiator for the unsaturated polyester is introduced into the mixture of heated foundary sand and the unsaturated polyester while the polyester is in the state of liquid coating on the sand particles, and stirring is continued to uniformly mix the solution with the unsaturated polyester and evaporate and dissipate the solvent before solidification of the polyester coating as the result of cooling of the mixture. The polyester coating contains no liquid cross-linking agent, so that the resin coated sand is untacky and high in fluidity at room temperature and, therefore, can be filled into a die cavity to shape a sand mold or core with sufficiently high bulk density.