| 摘要 |
PROBLEM TO BE SOLVED: To extremely reduce an optical defect by adding a specific amt. of a predetermined isocyanate compd. to a soln. for forming a cast film. SOLUTION: As a soln. for forming a cast film, a soln. prepared by adding an isocyanate compd. to a soln. prepared by dissolving a resin component in a solvent in an amt. of 5wt.% or less of the resin component is used. This isocyanate compd. is monofunctional or polyfunctional isocyanate compd. of which the b.p. under atmospheric pressure is 110 deg.C or higher, pref., 130 deg.C or higher. Further, an isocyanate compd. wherein the b.p. of a compd. formed by the reaction with water is 110 deg.C or higher, pref., 130 deg.C or higher is used. As this isocyanate compd., phenyl isocyanate, n-hexyl isocyanate or 1-naphthyl isocyanate is designated. Since moisture in a soln. is reacted with an isocyanate compd. and the isocyanate compd. is modified to a compd. having a higher b.p., the foaming caused by the sudden femoval of moisture at a time of heating and drying can be suppressed. |
