| 摘要 |
An optically anisotropic film comprising a liquid crystal composition having twisted nematic alignment, characterized in that the helical axis of twisted nematic alignment is substantially parallel to the direction normal to the film plane, and the liquid crystal composition shows a cholesteric phase, contains at least one liquid crystal oligomer selected from the linear or cyclic liquid crystal oligomers (A) such as obtained from reaction of a vinyl monomer having a specific cholesterol group and pentamethylcyclopentasiloxane, and is defined by the fact that when the thickness of the film is represented by d ( mu m) and the helical pitch of the twisted nematic phase is represented by P ( mu m), d >/= 3 x P and P </= 0.3 mu m or P >/= 0.8 mu m, wherein when the numbers of the recurring units (I) and (II) in one molecule of the liquid crystal oligomer (A) are supposed to be n and n', respectively, n and n' are each an integer of 1 to 20 and satisfy the relations of 4 </= n + n' </= 21 and n : n' = 20 : 1 to 1 : 20, and the terminal group of the recurring unit (II) of the liquid crystal oligomer (A) is polymerized. This optically anisotropic film is capable of providing a liquid crystal display device with smaller viewing angle dependency of contrast or display color. |
