Patent ID: 7641462

Claim:
An apparatus for producing a multi-layer film, comprising: a feed block for joining at a joining section a first polymer solution and a second polymer solution that flow in different flow paths, so as to form and feed out a casting polymer solution stream through a path exit, said second polymer solution having lower viscosity than said first polymer solution, said first and second polymer solutions flowing in parallel to each other in said casting polymer solution stream; a casting die for extending a width of a casting polymer solution stream fed out from said feed block and for casting said casting polymer solution stream through a die lip onto a support after the extending, so as to form a casting film having a multi-layer structure; an edge slitting device for slitting off edge portions of said casting film in a widthwise direction thereof, to obtain a production area of said casting film; a distribution pin provided in said joining section in said feed block; a groove formed on said distribution pin, for controlling a flowing width of said second polymer solution when said second polymer solution flows in said groove; wherein a width Wd and a depth Dd of said groove satisfies following formulae (1) and (2), 0.6( Wa Wc/Wb )< Wd< 1.14( Wa Wc/Wb ) 0.5( Da Dg/Df )< Dd< 3.2( Da Dg/Df ) Wa: width of said path exit Wb: width of said casting film, Wc: width of the production area of said casting film Da: depth of said path exit Df: thickness of layer formed from said first polymer film in said casting film Dg: thickness of layer formed from said second polymer film in said casting film, wherein said groove is constructed of a first groove area having said width Wd and said Depth Dd and a second groove formed in a middle of said first groove in a widthwise direction of a bottom of said first groove, and wherein a width We and a depth De of said second groove satisfy following formula (3), (4): 0.05Wd<We<0.15Wd, 0.15Dd<De<1.5Dd.