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用尿醛树指、氯化铵和辉绿岩铸石粉调制的耐磨胶,硬度高,耐磨性好,用它涂在木制农具上,比较有效地解决了泥沙对农具的磨损问题,这对木制机耕船的推广有一定的促进作用。本刊76年第4期《耐磨胶》一文中对胶的调制、涂敷和使用已作过详细介绍,现将使用中应注意的几个问题作一补充。 1.甲醛的杂质要少,否则胶层易出现裂纹。甲醛含有少量杂质时,最好不要用氢氧化钠去分离杂质,不然,甲醛的碱性变大,树脂合成时间延长,造成甲醛大量挥发,出胶少。另外,甲醛极易挥发,在存放过程中其含量逐渐减小,熬制尿醛树脂的配比也应有相应变化,具体计算如下:
Urea aldehyde refers to the tree, ammonium chloride and diabase cast stone modulation of the wear-resistant plastic, high hardness, good wear resistance, use it coated on wooden farm tools, more effective solution to the problem of sand on the tool wear and tear , Which promote the promotion of wooden plow has a certain role in promoting. This issue of 76, No. 4 “wear-resistant plastic,” a article on the plastic modulation, coating and use have been described in detail, now we should pay attention to a few questions to make a supplement. 1. Formaldehyde impurities less, or prone to cracks in the plastic layer. Formaldehyde contains a small amount of impurities, it is best not to use sodium hydroxide to separate impurities, otherwise, formaldehyde, alkaline become larger, the resin synthesis time, resulting in a large number of formaldehyde evaporation, less plastic. In addition, formaldehyde is very volatile, its content gradually decreases in the storage process, boil the ratio of urea resin should also have a corresponding change, the specific calculation is as follows: