| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a production method of a cellulose acylate film having excellent productivity of a long film and giving a polarizing plate excellent in durability and contrast property.SOLUTION: The production method of a cellulose acylate film aims to produce a laminate having a three-layer structure composed of a cellulose acylate layer A having an acyl group substitution degree of 2.7 or less and cellulose acylate layers B having an acyl group substitution degree larger than that of the layer A, on either side of the layer A. The method includes: a step (1) of preparing a cellulose acetate resin (a) solution 1 having an acyl group substitution degree of 2.7 or less; a step (2) of preparing a mixture solution 2 of a cellulose acetate resin (b) having an acyl group substitution degree of larger than 2.8 and a cellulose acetate resin (d) having an acyl group substitution degree of 2.7 or less, so as to obtain an acyl group substitution degree of larger than 2.7 in the layer B; and a step (3) of co-flow casing the solution 1 and the solution 2 to produce a film having a dry film thickness of the layer B in the range from 0.5 to 15μm.</p> |
