| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a driving belt which is high in heat resistance and low in tension lowering on an industrial scale by blanking a thermosetting resin molded into a sheet form by a soln. polymn. method to an annular shape and stretching this resin. SOLUTION: A soln. 1 prepd. by dissolving a prepolymer and a crosslinking agent in an org. solvent is dropped and spread on release paper 2 and after the solvent is vaporized in a drying furnace, the soln. is heated in a heating furnace 3 to accelerate curing, to form a urethane sheet of a thickness below 0.5 mm. At this time, the desired sheet thickness is obtd. by controlling the soln. viscosity by changing the solute density in the soln. The sheet is formed by the soln. polymn. method, by which the belt uniformly in a circumferential direction is obtd. without the occurrence of anisotropy. The thermosetting resin of the material is preferably thermosetting polyurethane or the like of which the essential components consists of org. diisocyanate, high-polymer diol and chain extender and which are workable at a high temp. and have excellent wear resistance and durability. The doughnut-shaped ring is blanked from this sheet and is stretched at the circumferential length under prescribed conditions, to obtain the belt.</p> |
