Patent ID: 7526878

Claim:
A method for drying a coating film comprising drying a coating film of an organic solvent-containing coating liquid applied to a running band-shaped flexible substrate, the drying method comprising the steps of: providing a heater at a position opposed to the band-shaped flexible substrate at a running position immediately after coating; and heating the band-shaped flexible substrate by the heater; wherein when T W ( ° C.) denotes the surface temperature of the band-shaped flexible substrate; T H ( ° C.) denotes the surface temperature of the heater; λ(W/m·K) denotes the heat-transfer coefficient of air; d(m) denotes the distance between the heater and the band-shaped flexible substrate (web); η denotes the efficiency of heat transfer; and η denotes the Stefan-Boltzmann constant (5.670×10 −8 W/m 2 K 4 ), the ratio of radiant heat transfer represented by Q R /(Q R +Q C ) is 0.25 or more and 0.6 or less, wherein Q C and Q R are represented by the following equations, respectively: Q C =λ/d ·( T H −T W ) where Q C denotes heat transfer by air, and Q R =ησ{( T H +273) 4 −( T W +273) 4 } where Q R denotes heat transfer by radiant.