Cellulose acylate film, optical compensation film, method of producing cellulose acylate film, polarizing plate and liquid crystal display
AssigneeFuji Photo Film Co., Ltd.
InventorsTadashi Omatsu, Takeshi Senga, Yutaka Nozoe, Nobutaka Fukagawa
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Abstract
A cellulose acylate film, which has small environment dependency, particularly humidity dependency, of optical performance and simultaneously has excellent polarizing plate processability, is provided. The cellulose acylate film has a an equilibrium water content and a humidity dependency of a retardation Rth in a thickness direction of the cellulose acylate film, in which a relationship between the equilibrium water content and the humidity dependency satisfies a condition specified in the specification.
Claims15
A cellulose acylate film having an equilibrium water content and a humidity dependency of a retardation Rth in a thickness direction of the cellulose acylate film, wherein a relationship between the equilibrium water content and the humidity dependency satisfies conditional expression (1):
- 0≦A≦12
- wherein A represents a value indicated by {−(Rth(80%)−Rth(10%))/(equilibrium water content (80%)−equilibrium water content (10%))};
- Rth(X %) is a Rth value under an ambience of 25° C. and X % RH, the Rth value being normalized to a Rth value of a cellulose acylate film having a thickness of 80 μm;
- and the equilibrium water content (X %) is a equilibrium water content under an ambience of 25° C. and X % RH.
A method of producing a cellulose acylate film, comprising:
- casting a cellulose acylate solution on a support at a temperature of −10° C. to 39° C., the cellulose acylate solution comprising:
- a compound satisfying conditional expression (4);
- and cellulose acylate;
- drying the cellulose acylate solution on the support by blowing dry air at a temperature of 55° C. to 180° C. to provide a flow cast film;
- peeling off the flow cast film from the support;
- and
- drying the flow cast film to produce a cellulose acylate film:
- 0≦R≦0.9 Conditional Expression (4)
- wherein R represents an index for a degree of influence of the cellulose acylate on a self-diffusion coefficient of the compound satisfying conditional expression (4) in the cellulose acylate solution, and R is expressed as RD (subject compound)/RD (comparison compound), wherein RD is Db/Da;
- Da represents a ratio of a self-diffusion coefficient of one of the subject compound and the comparison compound as a single solute when only the single solute is dissolved in a solution;
- Db represents a self-diffusion coefficient of the single solute when cellulose acylate is co-present in the solution;
- the subject compound is the compound satisfying conditional expression (4);
- and the comparison compound is adamantine.
Dependencies are inferred from the claim text.