Achromatic polarization element, and polarization plate
AssigneesNippon Kayaku Kabushiki Kaisha, Polatechno Co., Ltd.
InventorNoriaki Mochizuki
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Abstract
a* and b* values, which define, the hue of a polarization element or a polarization plate using JIS.Z.8729, are adjusted such that the absolute value of the a* and b* values is: less than 1 during a single-body transmittance measurement; less than 2 when two sheets of a 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.
Claims14
A polarization element comprising a stretched base material containing iodine and a dichroic dye that is an azo compound and having a polarizing function, wherein the polarization element is characterized in that:
- a* value and b* value of hue calculated in accordance with JIS Z 8729 are such that absolute values of the a* value and the b* value when single-body transmittance is measured are no more than 1, absolute values of the a* value and the b* value measured with two of the base materials being arranged in parallel with respect to an absorption axis direction are no more than 2, and absolute values of the a* value and the b* value measured with two of the base materials being arranged orthogonally with respect to the absorption axis direction are no more than 2;
- and
- the single-body transmittance is 35% or above, and
- wherein said polarization element comprises a plurality of azo compounds, and wherein the plurality of azo compounds comprises, an azo compound represented in a form of a free acid by formula (1) and an azo compound represented in a form of a free acid by formula (2);
- or an azo compound represented in a form of a free acid by formula (1) and an azo compound represented in a form of a free acid by formula (3):
- (wherein A1 represents a phenyl group or naphthyl group having a substituent group;
- R1 to R4 each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower alkoxy group having a sulfo group;
- X1 represents an amino group optionally having a substituent group, a benzoylamino group optionally having a substituent group, a phenylamino group optionally having a substituent group, or a phenylazo group optionally having a substituent group;
- k represents an integer of 0 or 1;
- and when k is 1, X1 represents a benzoylamino group optionally having a substituent group);
- (wherein A2 represents a phenyl group or naphthyl group having a substituent group;
- R5 represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower alkoxy group having a sulfo group;
- and X2 represents a hydrogen atom, a lower alkyl group, or a lower alkoxyl group);
- (wherein A3 represents a phenyl group having a substituent group;
- R6 to R9 each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower alkoxy group having a sulfo group;
- and R10 and R11 each independently represent a hydrogen atom, a methyl group, a methoxy group, a sulfo group, an amino group, or a substituted amino group, with the proviso that all of R6 to R9 do not represent a lower alkoxy group simultaneously.
Dependencies are inferred from the claim text.