METHOD AND APPARATUS FOR DRYING COATING FILM, AND METHOD FOR PREPARING OPTICAL FILM

PROBLEM TO BE SOLVED: To provide a method and apparatus for drying coating film at a high speed per unit surface area and per unit time upon drying a wide and long surface of coating film formed by applying a various liquid compositions onto a continuously traveling flexible support-belt. SOLUTION: The method for drying coating film formed on a continuously traveling flexible support-belt 11 (web 11) by heating the web 11 with a heater 40 disposed to face the web 11 immediately downstream of the coating position along the traveling route of the web 11 is characterized in that the ratio of heat transferred by radiation represented by the equation of QR/(QR+QC) is not lower than 0.25 and not higher than 0.6; wherein QCrepresents heat transferred via air as shown in the equation of QC=λ/d×(TH-TW), and QRrepresents heat transferred by radiation as shown in the equation of QR=ηä(TH+273)4-(TW+273)4} with TW(°C) representing a surface temperature of the flexible support-belt (web) 11, TH(°C) representing a surface temperature of the heater 40, λ(W/m×K) representing heat transfer coefficient of air, d (m) representing the distance between the heater 40 and the web 11, and η representing heat transfer efficiency. COPYRIGHT: (C)2008,JPO&INPIT