尿素系合成樹脂を粘結劑とする鋳物砂に対する二三の実験

抄録

  During and after the World War Ⅱ, synthetic resins have been used in England and the United States for core binders and have given good results in the foundry. According to the investigations, synthetic resins offer exceptional advantages as a core binder, i. e., rapid curing, high dry strength and excellent knock-out characteristics. In this paper, the properties for the core binder of urea-formaldehyde resins are described in compared with linseed oil on the basis of some experimental results. The dry strength of urea resin sand mixed with 2.5% resin is nearly equal to that of linseed oil sand with 4.5% oil, 1300 p.s.i. Gas volume evolved when baked resin sand is rapidly heated to high temperature is less than that when oil bonded sand, but resin begins to decompose earlier than oil. Baked urea resin sand (in air) adsorpts a little more moisture than linseed oil sand. But the suitable baking temperature of resin sand is lower and the baking time is shorter than those of oil sand. It is thought that urea resin is economical and a promising core binder.