This achromatic polarizing plate has a high transmissivity, while expressing an achromatic white color when the absorption axes of the polarizing elements are positioned in parallel, and expressing an achromatic black color when the absorption axes of the polarizing elements are positioned orthogonally to one another. This polarizing element contains at least two specific azo compounds, and the absolute value of the difference between the average transmissivity of 420 nm to 480 nm light and the average transmissivity of 520 nm to 590 nm light is equal to or less than 2.5, and the absolute value of the difference between the average transmissivity of 520 nm to 590 nm light and the average transmissivity of 590 nm to 640 nm light is equal to or less than 2.0.

This achromatic polarizing plate has a high transmissivity, while expressing an achromatic white color when the absorption axes of the polarizing elements are positioned in parallel, and expressing an achromatic black color when the absorption axes of the polarizing elements are positioned orthogonally to one another. This polarizing element contains at least two specific azo compounds, and the absolute value of the difference between the average transmissivity of 420 nm to 480 nm light and the average transmissivity of 520 nm to 590 nm light is equal to or less than 2.5, and the absolute value of the difference between the average transmissivity of 520 nm to 590 nm light and the average transmissivity of 590 nm to 640 nm light is equal to or less than 2.0.

An azo compound and an ink composition containing the azo compound are used as inks for ink jet recording and have excellent gas (ozone) resistance when recording is done on special ink jet paper. The azo compound is represented by formula (1) or a tautomer thereof, or a salt of these. In formula (1), R.sup.1 represents a C1-C4 alkyl group, R.sup.2 represents a cyano group, R.sup.3 and R.sup.4 each independently represent a C1-C4 alkoxy, R.sup.5-R.sup.10 each independently represent a group represented by formula (2), and R.sup.11-R.sup.13 each independently represent a nitro group. In formula (2), R.sup.14 is an anilino group, and R.sup.15 is a mono- or di-C1-C6 alkylamino group

##STR00001##

An azo compound and an ink composition containing the azo compound are used as inks for ink jet recording and have excellent gas (ozone) resistance when recording is done on special ink jet paper. The azo compound is represented by formula (1) or a tautomer thereof, or a salt of these. In formula (1), R.sup.1 represents a C1-C4 alkyl group, R.sup.2 represents a cyano group, R.sup.3 and R.sup.4 each independently represent a C1-C4 alkoxy, R.sup.5-R.sup.10 each independently represent a group represented by formula (2), and R.sup.11-R.sup.13 each independently represent a nitro group. In formula (2), R.sup.14 is an anilino group, and R.sup.15 is a mono- or di-C1-C6 alkylamino group

##STR00001##

An azo compound represented by the following formula (1) or a salt thereof, Wherein A.sup.1 represents a naphthyl group which may have a substituent; A.sup.2, A.sup.3, and A.sup.4 each independently represent a phenyl group which may have a substituent or a naphthyl group which may have a substituent; R.sup.1 represents a hydrogen atom, a hydroxy group, a C1-4 alkoxy group, or a substituted or unsubstituted amino group; m represents an integer of 0 to 5; M represents a hydrogen atom or ion, a metal ion, or an ammonium ion; n represents 1 or 2; k represents 0 or 1; and each hydrogen atom on ring a and ring b may be substituted with the substituent R.sup.1 or substituent SO.sub.3M. ##STR00001##

An azo compound represented by the following formula (1) or a salt thereof, Wherein A.sup.1 represents a naphthyl group which may have a substituent; A.sup.2, A.sup.3, and A.sup.4 each independently represent a phenyl group which may have a substituent or a naphthyl group which may have a substituent; R.sup.1 represents a hydrogen atom, a hydroxy group, a C1-4 alkoxy group, or a substituted or unsubstituted amino group; m represents an integer of 0 to 5; M represents a hydrogen atom or ion, a metal ion, or an ammonium ion; n represents 1 or 2; k represents 0 or 1; and each hydrogen atom on ring a and ring b may be substituted with the substituent R.sup.1 or substituent SO.sub.3M. ##STR00001##

Azo-azomethine dyes, a dichroic dye mixture including azo-azomethine dyes, a liquid crystal composition with the azo-azomethine dyes, and methods for producing the dyes and dye compositions. The dyes can be used in liquid crystal systems, transmissive displays, and smart windows. ##STR00001##

Azo-azomethine dyes, a dichroic dye mixture including azo-azomethine dyes, a liquid crystal composition with the azo-azomethine dyes, and methods for producing the dyes and dye compositions. The dyes can be used in liquid crystal systems, transmissive displays, and smart windows. ##STR00001##

A polarizer contains, in a base thereof, at least one of an azo compound represented by Formula (1) or a salt thereof (as compound A), and at least one of an azo compound represented by Formula (2-I), (2-II), (3), (4-I), (4-II), (5-I) or (5-II), or a salt thereof (as compound B).

A polarizer contains, in a base thereof, at least one of an azo compound represented by Formula (1) or a salt thereof (as compound A), and at least one of an azo compound represented by Formula (2-I), (2-II), (3), (4-I), (4-II), (5-I) or (5-II), or a salt thereof (as compound B).