| 摘要 |
<p>Abrasive based on silica sand or slag grains. The sand or slag (a) is coated with a thermosetting resin (b) which is then made insol. and unmeltable. Resin (b) pref. contains a hardening catalyst (c). The pref. abrasive uses 100 pts. silica and No. 4 (JIS) with 2 pts. resin (b) and 1 pt. cpd. (c). The mixt. (a,b,c) is pref. made in the presence of hot air to form a coating on sand (a); followed by reheating to make the coating insol. and unmeltable, esp. in a rotary drum furnace fed with a counter-current of hot air. Alternatively, reheating may be achieved via infrared heaters located above a vibratory conveyor. Used esp. for sand blasting, where conventional sand grains fracture to form dust polluting the environment and damaging the health of workers. The hard resin coating increases the abrasive effect and also prevents breakdown of the sand into dust.</p> |
