Production method of polymer film
AssigneeFUJIFILM Corporation
InventorsKoju Ito, Hidekazu Yamazaki, Yoshiaki Narukawa, Hiromasa Tanaka
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Abstract
A primary dope is obtained by mixing solvent and polymer, and an additive is added to the primary dope so as to prepare three sorts of dopes. The dopes are cast from a casting die onto a casting belt to form three-layer film. The thickness of the first layer t1 is the same as the thickness of the third layer t3 or less, and the thickness of the third layer t3 is the same as the thickness of the second layer t2 or less. After the film is peeled from the casting belt, both side edge portions of the film are clipped by clips. The film is stretched in a widthwise direction and dried. The film is excellent in smoothness and optical properties.
Claims13
A production method of a polymer film, comprising steps of:
- adding an additive to a primary dope as a mixture of a polymer and an organic solvent so as to prepare three sorts of dopes;
- casting said dopes on a moving support, so as to form a casting film having three layers superimposed, said three layers being a first layer of thickness t1 (μm), a second layer of thickness t2 (μm) and an third layer of thickness t3 (μm), at least one of said thickness t1, t2 and t3 being different, a condition t1≦t3≦t2 being satisfied;
- peeling from said support said casting film as a wet film containing said organic solvent;
- clipping both side edge portions of said wet film by a clipping member;
- stretching said wet film in a widthwise direction by moving said clipping member;
- and
- drying said wet film during said stretching such that said polymer film may be obtained.
Dependencies are inferred from the claim text.