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.

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An object of the invention is to provide a dichroic substance capable of forming a light absorption anisotropic film having excellent light fastness, a composition, a light absorption anisotropic film formed of the composition, a laminate, and an image display device. A composition according to the embodiment of the invention is a composition containing a dichroic substance having an azo group, and the dichroic substance exhibits a highest occupied molecular orbital energy level of 5.60 eV or less and a CLogP value of 7.0 or greater.

An object of the invention is to provide a dichroic substance capable of forming a light absorption anisotropic film having excellent light fastness, a composition, a light absorption anisotropic film formed of the composition, a laminate, and an image display device. A composition according to the embodiment of the invention is a composition containing a dichroic substance having an azo group, and the dichroic substance exhibits a highest occupied molecular orbital energy level of 5.60 eV or less and a CLogP value of 7.0 or greater.

The present invention relates to an azo compound that is useful as a dichroic pigment used in a polarizing plate having excellent polarizing performance and durability and having little color leakage in a visible light region, and used in a neutral gray polarizing plate for vehicle mounting that uses the aforementioned polarizing plate. More specifically, the invention relates to an azo compound that is represented by formula (1) [In the formula, R.sub.1-R.sub.4 each independently represent a hydrogen atom, a C1-5 alkyl group, a C1-5 alkoxy group, a sulfo group, or a C1-5 alkoxy group having a sulfo group, X represents an amino group having a substituent, a benzoylamino group having a substituent, a phenylamino group having a substituent, a phenylazo group having a substituent, or a naphthotriazole group having a substituent, m represents 3 or 4, n represents 1 or 2, and p represents 1, 2, or 3.], or to a salt of said compound.

The present invention relates to an azo compound that is useful as a dichroic pigment used in a polarizing plate having excellent polarizing performance and durability and having little color leakage in a visible light region, and used in a neutral gray polarizing plate for vehicle mounting that uses the aforementioned polarizing plate. More specifically, the invention relates to an azo compound that is represented by formula (1) [In the formula, R.sub.1-R.sub.4 each independently represent a hydrogen atom, a C1-5 alkyl group, a C1-5 alkoxy group, a sulfo group, or a C1-5 alkoxy group having a sulfo group, X represents an amino group having a substituent, a benzoylamino group having a substituent, a phenylamino group having a substituent, a phenylazo group having a substituent, or a naphthotriazole group having a substituent, m represents 3 or 4, n represents 1 or 2, and p represents 1, 2, or 3.], or to a salt of said compound.

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 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##

The present invention relates to an azo compound that is useful as a dichroic pigment used in a polarizing plate having excellent polarizing performance and durability and having little color leakage in a visible light region, and used in a neutral gray polarizing plate for vehicle mounting that uses the aforementioned polarizing plate. More specifically, the invention relates to an azo compound that is represented by formula (1) [In the formula, R.sub.1-R.sub.4 each independently represent a hydrogen atom, a C1-5 alkyl group, a C1-5 alkoxy group, a sulfo group, or a C1-5 alkoxy group having a sulfo group, X represents an amino group having a substituent, a benzoylamino group having a substituent, a phenylamino group having a substituent, a phenylazo group having a substituent, or a naphthotriazole group having a substituent, m represents 3 or 4, n represents 1 or 2, and p represents 1, 2, or 3.], or to a salt of said compound.

The present invention relates to an azo compound that is useful as a dichroic pigment used in a polarizing plate having excellent polarizing performance and durability and having little color leakage in a visible light region, and used in a neutral gray polarizing plate for vehicle mounting that uses the aforementioned polarizing plate. More specifically, the invention relates to an azo compound that is represented by formula (1) [In the formula, R.sub.1-R.sub.4 each independently represent a hydrogen atom, a C1-5 alkyl group, a C1-5 alkoxy group, a sulfo group, or a C1-5 alkoxy group having a sulfo group, X represents an amino group having a substituent, a benzoylamino group having a substituent, a phenylamino group having a substituent, a phenylazo group having a substituent, or a naphthotriazole group having a substituent, m represents 3 or 4, n represents 1 or 2, and p represents 1, 2, or 3.], or to a salt of said compound.