| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a film reduced in retardation Rth in its thickness direction. <P>SOLUTION: A dope 36 is prepared using cellulose acetate propionate (CAP) as a raw material and cast on a casting band 72 from a casting die 71 to which a feed block 70 is attached to form a cast film 80. The cast film 80 having self-supporting properties is peeled as a wet film 87 to send the wet film 87 to a tenter 100. The surface temperature of the wet film 87 is adjusted to the glass transition temperature Tg(°C) of the wet film 87 or above and a tension of 80 N/m or above to the wet film 87 in the stretching direction of the wet film 87 to form a film 101. The film 101 has in-plane retardation Re of a desired magnitude but the orientation of the CAP molecule in the thickness direction of the film is relaxed to reduce retardation Rth. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
