| 摘要 |
PURPOSE:To obtain a binder having moderate moldability, heat resistance and thermally decomposable property by specifying the max. rate of loss of weight and specifying temp. and loss of weight under heating conditions of specific rates of temp. elevation. CONSTITUTION:This is a binder of which the max. rate of loss of weight is <=25wt%/min and the loss of weight at 450 deg.C is >=30wt% and <=75wt% when it is heated at 20 deg.C rate of temp. elevation per minute in air. This is produced by a method of selecting an org. compound which is, for example, the 1st component, and an initial condensate of a thermosetting resin which is the 2nd component as a combiation wherein a common solvent exists, dissolving this in a solvent, and mixing the soln. with casting sand then evaporating the solvent away thereby obtaining the sand coated with the mixture of the two components. Then, this coated sand is packed in core molding molds, and is subjected to a heat treatment, whereby the sand is bound simultaneously with the partial reaction of the two components and the core molding is obtained. |
