Patent ID: 8197726
Filing Date: 2012-06-12
Classification: B29C,B29K,C08J,C09K,G02B,G02F

Abstract:
1. A method for producing a cellulose acylate film, comprising: melt-casting a cellulose acylate satisfying Formulae (1) to (3) to form a film with use of a melt extruder having a screw in which a portion corresponding to 5 to 34% of the entire length of the screw from the most upstream end of the screw is cooled to a temperature of Tg or less of the cellulose acylate and the ratio of the length of a feeding zone to the length of a compression zone is in the range of 1.2:1 to 10:1, and wherein a temperature of an outlet side of a barrel including the screw of the melt extruder is higher than a temperature of an inlet side of the barrel including the screw of the melt extruder, by 5 to 80° C.: wherein X represents a substitution degree for an acetyl group and Y represents the sum of the substitution degrees for a propionyl group, a butyryl group, a pentanoyl group and a hexanoyl group, and wherein the number of V-shaped thickness-uneven portions having a thickness variation in the thickness direction of 0.1 to 10% of a film thickness and a width in the in-plane direction of 1 to 20 mm is in the range of 0 to 5 per 100 m in the length direction of the film.