the CTL is preferably not less than 70 parts by weight per 100 parts by weight of the resin components in the CTL. Suitable solvents for use in the CTL coating liquid include ketone such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone; ethers such as dioxane, tetrahydrofuran, and ethyl cellosolve; aromatic solvents such as t