| 摘要 |
PURPOSE:To improve the collapsing property of a casting mold by compounding specific % of a novolak resin which is condensed by an acidic catalyst and is added with a phosphorus compd. etc., with a resol resin prepd. by co- condensation of a polyhydric phenol and formaldehyde with a phenol. CONSTITUTION:The resol resin is formed by addition and cocondensation of 0.15-2.0mol polyhydric phenol and 1.15-10.5mol formaldehyde with 1.0mol phenol by an alkaline catalyst. The novolak resin is then prepd. by condensing 0.6-1.6mol formaldehyde with 1.0mol phenol by an acidic catalyst, then adding a prescribed ratio of phosphate, etc., thereto and is compounded with the resol resin at 35-100pts.wt. with 100pts. with said resin to form a binder. The oxygen atoms contained in the phenolic resin in the binder increase and the rate of carbonization increases, by which the collapsing property of the casting mold is improved.
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