Patent ID: 8247041
Filing Date: 2012-08-21
Classification: B29C,B29K,B29L,C08J,C09K,Y02P,Y10T

Abstract:
1. A method of producing a cellulose acylate film comprising a step of melt-casting film formation from a melt of a cellulose acylate composition that contains a fatty acid having from 2 to 6 carbon atoms and has a sulfuric acid amount of from 0 ppm to 200 ppm, wherein the cellulose acylate satisfies formula (4): where X represents a substitution degree for an acetyl group; Y represents a total substitution degree for a propionyl group, a butyryl group, a pentanoyl group and a hexanoyl gram; wherein when at least ½ of Y is a propionyl group, the cellulose acylate further satisfies formula (5): when less than ½ of Y is a propionyl group, the cellulose acylate further satisfies formula (8): wherein the melt has a storage elastic modulus G′ at 180° C. to 240° C. of from 100 Pa to 30000 Pa, a loss elastic modulus G″ at 180° C. to 240° C. of from 1000 Pa to 30000 Pa and a tan δ at 180° C. to 240° C. of from 1 to 6 where tan δ is computed as G″/G′, and wherein prior to any stretching step, on the surface of the film, the total of: the number of projections having a height of from 0.1 μm to 100 μm and a length of at least 1 mm, and the number of depressions having a depth of from 0.1 μm to 100 μm and a length of at least 1 mm, is at most 10 per 10 cm of the width of the film.