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分析了国内３种生产工艺和材料基本相同的酚醛树脂和国外一种覆膜砂专用酚醛树脂的性能和覆膜砂强度的关系。提出为了提高覆膜砂强度，降低酚醛树脂中游离酚含量，必须要使树脂的软化点保持在相对较低的水平，使分子量较低的观点，为改进覆膜砂专用酚醛树脂的生产工艺指明了方向
The relationship between the properties of three kinds of phenolic resins with the same production process and materials and the special phenolic resin used in foreign countries and the strength of the coated sand was analyzed. It is proposed that in order to improve the strength of coated sand and reduce the content of free phenol in the phenolic resin, it is necessary to keep the softening point of the resin at a relatively low level and to make the production process of the special phenolic resin coated with sand clear from the viewpoint of low molecular weight The direction