| 摘要 |
PROBLEM TO BE SOLVED: To impart a good unwindability to a plastic film roll used for a vacuum treatment by specifying the expansion power of the roll to a certain value or lower. SOLUTION: This plastic film roll is prepd. so as to have an expansion power of 180 Pa or lower. Pref., the film has a thickness of 0.5-15μm and is a vacuum-metallizable one, e.g. a polyester film. Such a roll is prepd. by winding the film under such conditions of temp, humidity, and pressure that the distance between layers of the wound film is made as small as possible, the amt. of air entrapped is reduced to as small as possible, and the characteristics of air entrapped are suitable for the vacuum treatment. More specifically, the roll is prepd. by winding and drying while decreasing the winding tension from 24.5 Pa to 19.6 Pa linearly with the increase in the roll diameter and increasing the plane pressure from 539 N/m to 637 N/m linearly with the increase in the roll diameter or without changing the plane pressure.
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