Patent ID: 8808795

Claim:
A method of producing a laminate film comprising coating a continuously traveling support with coating solutions each containing one or more monomers or polymers with at least two monolayer extrusion dies to provide layers; wherein a difference in solubility parameter between the coating solution and a solute in the adjoining layer is not smaller than 0.1 for the respective coating solutions; a viscosity of the coating solution discharged from a downstream side die is lower than that of the coating solution discharged from an upstream side die for the adjoining layers; each of the coating solutions has a Capillary number Ca which satisfies a condition: Ca<1.7; a difference in surface tension |σ2−σ1| between the adjoining layers satisfies a condition: |σ2−σ1|>0.5 [mN/m], where σ1 is a surface tension of the coating solution discharged from the upstream side die and σ2 is a surface tension of the coating solution discharged from the downstream side die; a ratio h 1 /L between a coating thickness h 1 [μm] of the coating solution for an upper layer of the adjoining layers and a distance L [μm] of the upper layer from the support surface satisfies a condition: h 1 /L<0.14; and a distance M between discharge nozzles of the adjoining monolayer extrusion dies is 1 mm or more and 700 mm or less.