| abstract |
The present invention pertains to a polyvinyl acetal resin film made of a polyvinyl acetal resin material, wherein the thickness thereof is 5-350 μm, formula (1): Rz1(a) > 1.1 × Rz2(a), and formula (2): 3 > Rz2(a) are satisfied, where Rz1(a) (µm) represents the average value of the ten-point average roughness of surface A which is one surface of the film rougher than the other surface, and Rz2(a) (μm) represents the average value of the ten-point average roughness of surface B which is the smoother surface, and the value obtained by dividing the standard deviation of the ten-point average roughness of surface A by Rz1(a) and the value obtained by dividing the standard deviation of the ten-point average roughness of surface B by Rz2(a) are each 0-0.30, the viscosity of a 10-mass% concentration toluene/ethanol = 1/1 (mass ratio) solution of a polyvinyl acetal resin in the polyvinyl acetal resin material is 100-1000 mPa·s as measured using a Brookfield-type (B-type) viscometer at 20°C and 30 rpm, and the amount of a plasticizer in the polyvinyl acetal resin film is 0-20 mass% with respect to the total mass of the polyvinyl acetal resin film. |