Method for producing cellulose acylate film
AssigneeFUJIFILM Corporation
InventorsMasaru Sugiura, Fumio Kawamoto
Life of this patent
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Abstract
A casting film (24) is formed by casting a cellulose acylate solution (16) onto a cold drum (22) continuously running. The cellulose acylate solution (16) contains at most 0.01% of a compound which is extracted to a liquid incompatible with the water in a mixture of the water and the liquid. That is, at most 50 mg of the compound is contained in 100 g of cellulose acylate. In the cellulose acylate solution (16), a concentration C1 of Ca is at most 100 ppm, a proportion of the C1 to a concentration C2 of sulfuric acid satisfies the following formula: 0.5≦C1/C2≦1.5, and a concentration of Mg is in the range of 5 ppm to 50 ppm. Thereby, contamination of the surface of the cold drum (22) is prevented.
Claims8
A method for producing a cellulose acylate film comprising the steps of:
- preparing a cellulose acylate solution by dissolving cellulose acylate in a solvent, a concentration of a compound in said cellulose acylate is 0% or at most 0.05% to be extracted to a liquid incompatible with the water in a mixture of said liquid and the water;
- casting a cellulose acylate solution onto a support running continuously to form a casting film;
- peeling off said casting film as a film from said support;
- and
- drying said film by a drying device while said film being advanced.
Dependencies are inferred from the claim text.