フラン及びオイル・ウレタン鋳型の常温並びに高温性質

抄録

  A comparison of two nobake binders (low-nitrogen furan and oil-urethane) is presented. The discussion centers around effects of different sands, hot compressive strength and gas evolution. Twenty four hour compressive strengths were studied at catalyst levels which produce strip times in the range of 45-60min. Furan binder exhibits stronger adhesive strength at the binder-sand interface, and wets the sand surface more easily than urethane binder. This is the reason why furan binder is sensitive to the nature of sand grains. To reduce the binder level, dry sand reclamation which retains the smooth resin film on the sand grains is recommended. The lower hot strength of urethane binder is explained based on the level of residual carbon which is calculated from the gaseous decomposition products derived from resins upon exposure to 1,000°C. Furan core has larger H₂O (cal.50%) and less H₂ and hydrocarbons as compared with urethane core. During 4 min of exposure at 1,200°C, urethane core generates 90% of the total gas whereas the furan core produces only 50% of the gas, However, during 8 min of exposure at 400°C, urethane core exhausts only 40% of gas, while furan core emit 80% of gas.