[Problem] To provide a highly-transmissive polarization plate that can express achromatic white when a polarization element is arranged parallel to an absorbing axis, and achromatic black when the polarization element is arranged orthogonal to the absorbing axis.
[Solution] A polarization element, which is obtained from a base material containing a dichromatic dye formed from an azo compound, is characterized in that the single-body transmittance is 35-60%, and a* and b* values, which are acquired for a polarization element or a polarization plate using JIS·Z·8729, have an a* and b* absolute value that is: less than 1 in a single-body transmittance measurement; less than 2 when two sheets of the base material are arranged parallel to the absorbing axis direction and the a* and b* values are measured; and less than 2 when two sheets of the base material are arranged orthogonal to the absorbing axis direction and the a* and b* values are measured.
[问题]提供一种高透光率的偏振片,当偏振元件平行于吸收轴布置时,该偏振片可显示消色白,当偏振元件正交于吸收轴布置时,该偏振片可显示消色黑。
[解]一种偏振元件是由含有由偶氮化合物形成的二色
染料的基体材料制成的,其特征在于单体透射率为 35-60%,使用 JIS-
Z-8729 获取偏振元件或偏振片的 a* 和 b* 值,其 a* 和 b* 的绝对值为在单体透射率测量中小于 1;当两片基底材料平行于吸收轴方向排列并测量 a* 和 b* 值时,小于 2;当两片基底材料正交于吸收轴方向排列并测量 a* 和 b* 值时,小于 2。