| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a dustproof film having high light-transmitting property, excellent resistance against light and a long service life by using a cellulose propionate having specified weight-average mol.wt. in terms of a polystyrene standard thereby forming the dustproof film for protection of a photomask. SOLUTION: This device consists of a turntable 1 which is driven to rotate and a substrate 2 mounted on the turntable 1. The substrate 2 is rotated and the upper surface of the substrate 2 is kept horizontal to make a horizontal plane 3. By supplying a cellulose propionate soln. from a nozzle 4 on the horizontal plane 3 and rotating the turntable, the substrate 2 is also rotated to spread the cellulose propionate soln. into a thin film over the horizontal plane by the centrifugal force to form a cellulose ester thin film. The obtd. dustproof film has 60000 to 470000 weight average mol.wt. in terms of a polystyrene standard. If the weight average mol.wt. is too small, the film strength is not suitable for practical use, and if the mol.wt. is too large, the solubility of the cellulose with a solvent decreases and a uniform film can not be formed.</p> |
