| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a polarization film excellent in optical characteristics. <P>SOLUTION: The manufacturing method of a polarization film includes steps of performing: a swelling treatment; a dyeing treatment; a boric acid treatment; and a washing treatment on a polyvinyl alcohol type film 1 in this order, and before or during any of the steps, the polyvinyl alcohol type film 1 is subjected to a uniaxial stretching utilizing a circumferential speed difference between two nip rolls 2 and 2'. The uniaxial stretching includes a step in which at least one widening roll 3 is positioned between the two nip rolls 2 and 2' to carry out widening and uniaxial stretching on the polarization film. Integrated stretching ratio up to the widening step including the widening step (when any other stretching step is not included up to the widening step, the stretching ratio at the widening step) is 1.6 times or more; and in the widening step, an angle in the widening direction of the widening roll 3 with respect to the transportation direction of the film 1 fed out from the widening roll 3 is within the range of -40°-70° (here, a transportation direction of the film from the widening roll as the flow direction of the film is viewed from the left to the right is defined as 0°; the clockwise angle with respect to the transportation direction is defined as -; and a counterclockwise angle is defined as +). <P>COPYRIGHT: (C)2012,JPO&INPIT |
