JP5015911B2 - Diimonium salt compound, near-infrared absorbing composition containing the same, near-infrared absorbing filter, front plate for display - Google Patents

Description

  The present invention relates to a diimonium salt compound used in the production of a near-infrared filter and the like, a near-infrared absorbing composition containing the same, a near-infrared absorbing filter, and a display front plate.

  In recent years, various types of displays have been developed and commercialized as large displays, and one of them is a plasma display. In a display panel constituting a plasma display (referred to as a plasma display panel, hereinafter abbreviated as “PDP”), a mixed gas containing xenon and neon is enclosed between two glass plates. When a high voltage is applied to the mixed gas, ultraviolet rays are generated, and the phosphors emit light when the ultraviolet rays are applied to the glass plate.

During the discharge, near infrared rays having a wavelength of 850 nm to 1100 nm are also emitted simultaneously with ultraviolet rays. Since the near infrared wavelength region overlaps with the near infrared communication or remote control wavelength region of home electronic devices, the near infrared rays emitted from the PDP cause malfunction of the electronic device. Therefore, near infrared rays are conventionally absorbed on the front plate of the PDP using a near infrared filter containing a diimonium salt compound having near infrared absorption ability (see, for example, Patent Documents 1 and 2). Although the detailed reason is unknown, for the reasons such as ease of synthesis, price, and durability, compounds having a linear alkyl group as a terminal group have been frequently used as the diimonium salt compound. In addition, the use of a diimonium salt compound having higher heat resistance than a compound having a linear alkyl group and having a branched alkyl group such as an iso-butyl group as a terminal group has already been disclosed.
JP 61-69991 A Japanese Examined Patent Publication No. 6-26028 Japanese Patent No. 3699464

  However, a diimonium salt compound having a linear alkyl group has a property of easily changing with respect to humidity. For this reason, there has been a problem that near-infrared absorptivity decreases with time. The diimonium salt compound having a branched alkyl group such as an iso-butyl group as a terminal group is not sufficient in heat and heat resistance, and particularly has a problem that the ability to absorb near infrared rays having a relatively short wavelength decreases with time. there were.

  The present invention provides a near-infrared absorbing compound (diimonium salt compound) excellent in wet heat resistance, a near-infrared absorbing composition containing the same, a near-infrared absorbing filter, and a display front plate.

  The first diimonium salt compound of the present invention is characterized by having a structure represented by the following formula (1).

However, in the formula (1), X is an anion required to neutralize the charge, at least one of the rings A and B may have a substituent, R ₁ to R ₈ may be the same or different, and at least one of R _{1 to} R ₈ is represented by a cyclic alkyl group represented by the following formula (2) or represented by the following formula (3). An alkylene group having a cyclic alkyl group.
-(B) (2)
-(A)-(B) (3)
However, in Formula (2) and Formula (3), (B) is a cyclic alkyl group having 3 to 10 carbon atoms, and (B) may have a substituent. In Formula (3), (A) is an alkylene group having 1 to 10 carbon atoms, and (A) may have a substituent.

ただし、式（４）中において、Ｘは電荷を中和させるのに必要なアニオンであり、環Ａおよび環Ｂのうちの少なくとも１つは置換基を有していてもよく、Ｒ₁〜Ｒ₈は、それぞれ同一であっても、異なっていてもよく、Ｒ₁〜Ｒ₈のうちの少なくとも一つはアルコキシアルキル基である。 The second diimonium salt compound of the present invention is characterized by having a structure represented by the following formula (4).

However, in formula (4), X is an anion necessary for neutralizing the charge, and at least one of ring A and ring B may have a substituent, and R _{1 to} R ₈ may be the same or different, and at least one of R _{1 to} R ₈ is an alkoxyalkyl group.

  The near-infrared absorbing composition of the present invention comprises the first diimonium salt compound of the present invention or the second diimonium salt compound of the present invention and a resin.

  The near-infrared absorption filter of the present invention includes the first diimonium salt compound of the present invention or the second diimonium salt compound of the present invention.

  The display front plate of the present invention includes the near infrared absorption filter of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the near-infrared absorption compound (diimonium salt compound) excellent in heat resistance and moisture resistance, the near-infrared absorption composition containing this, a near-infrared absorption filter, and the display front board can be provided.

  Hereinafter, an example of the present invention will be described in detail.

(Embodiment 1)
In Embodiment 1, the first diimonium salt compound of the present invention will be described. The first diimonium salt compound of the present invention has a structure represented by the above formula (1).

  In the formula (1), X is an anion necessary for neutralizing the electric charge. Examples of monovalent anions include chloride ions, bromide ions, iodide ions, perchlorate ions, nitrate ions, benzenesulfonate ions, p-toluenesulfonate ions, methyl sulfate ions, ethyl sulfate ions, and propyl sulfate. Ion, tetrafluoroborate ion, tetraphenylborate ion, hexafluorophosphate ion, benzenesulfonate ion, acetate ion, trifluoroacetate ion, propionacetate ion, benzoate ion, oxalate ion, succinate ion, malon Acid ion, oleate ion, stearate ion, citrate ion, diphosphate hydrogen ion, dihydrogen phosphate ion, pentachlorostannate ion, chlorosulfonate ion, fluorosulfonate ion, trifluoromethanesulfonate ion, hexa Fluoro Arsenate ion, hexafluoroantimonate ion, molybdate ion, tungstate ion, titanate ion, zirconate ion, hexafluorophosphate ion, hexafluoroantimonate ion, bis (trifluoromethanesulfone) imido ion, Anions such as bis (pentafluoroethanesulfone) imido ion, pentafluoroethanesulfone trifluoromethanesulfonimidate ion, trifluoromethanesulfone heptafluoropropanesulfonimidate ion, or nonafluorobutanesulfone trifluoromethanesulfonimidate ion Is mentioned. Of these, hexafluorophosphate ions are particularly preferable.

  Examples of the divalent anion include naphthalene-1,5-disulfonic acid, R acid, G acid, H acid, benzoyl H acid, p-chlorobenzoyl H acid, p-toluenesulfonyl H acid, chloro H acid, chloro. Acetyl H acid, methanyl γ acid, 6-sulfonaphthyl-γ acid, C acid, ε acid, p-toluenesulfonyl R acid, naphthalene-1,6-disulfonic acid, 1-naphthol-4,8-disulfonic acid, etc. Naphthalene disulfonic acid derivative, carbonyl J acid, 4,4′-diaminostilbene-2,2′-disulfonic acid, diJ acid, naphthalic acid, naphthalene-2,3-dicarboxylic acid, diphenic acid, stilbene-4,4 '-Dicarboxylic acid, 6-sulfo-2-oxy-3-naphthoic acid, anthraquinone-1,8-disulfonic acid, 1,6-diaminoanthraquinone-2,7-disulfone Acid, 2- (4-sulfophenyl) -6-aminobenzotriazole-5-sulfonic acid, 6- (3-methyl-5-pyrazolonyl) -naphthalene-1,3-disulfonic acid, 1-naphthol-6- ( And divalent organic acid ions such as 4-amino-3-sulfo) anilino-3-sulfonic acid.

  At least one of ring A and four rings B may have 1 to 4 substituents other than the 1,4-position, or may not have a substituent. Examples of the substituent include at least one substituent selected from the group consisting of a lower alkyl group, a lower alkoxy group, a cyano group, a halogen atom, and a hydroxyl group. As a lower alkyl group, a C1-C5 alkyl group, such as a methyl group and an ethyl group, is mentioned, for example. As a lower alkoxy group, C1-C5 alkoxy groups, such as a methoxy group and an ethoxy group, are mentioned, for example. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  When at least one of the ring A and the four rings B has a substituent, the substituent is preferably a halogen atom (especially a chlorine atom or a bromine atom), a methyl group, or a cyano group.

  When all four rings B have a substituent, it is preferable that all the substituents are the same. In this case, the position of the substituent is preferably m-position with respect to the nitrogen atom bonded to the phenylenediamine skeleton, since it is easy to synthesize.

  It is more preferable in the synthesis of the diimonium salt compound that the ring A and the four rings B have no substituent other than the 1,4-position.

At least one of R _{1 to} R ₈ is an alkylene group having a cyclic alkyl group represented by the above formula (2) or a cyclic alkyl group represented by the formula (3). Since the diimonium salt compound of the present embodiment includes the cyclic alkyl group or the alkylene group having the cyclic alkyl group, the diimonium salt compound has good stability due to steric hindrance by the cyclic alkyl group. Although carbon number of a cyclic alkyl group should just be 3-10 pieces, 3-8 pieces are preferable from a viewpoint of cost. The number n of carbon atoms of the alkylene group (— (CH ₂ ) _n —) may be 1 to 10.

When the cyclic alkyl group has a substituent described later, the above “3 to 10” or “3 to 8” is a number not including carbon of the substituent, and an alkylene group (— (CH ₂ ) _n When-) has a substituent described later, the above “1 to 10” is a number that does not include carbon of the substituent.

  (B) in Formula (2) and Formula (3), and (A) in Formula (3) may have a substituent. Examples of the substituent include a cyano group, a hydroxyl group, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, an alkoxyalkoxy group having 2 to 8 carbon atoms, an alkoxyalkoxyalkoxy group having 3 to 15 carbon atoms, an allyloxy group, and a carbon number. Examples thereof include an aryloxy group having 6 to 12 carbon atoms, an alkoxycarbonyl group having 2 to 7 carbon atoms, an alkylcarbonyloxy group having 2 to 7 carbon atoms, and an alkoxycarbonyloxy group having 2 to 7 carbon atoms.

  Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom. Examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, and an n-butoxy group. Examples of the alkoxyalkoxy group having 2 to 8 carbon atoms include methoxymethoxy group, ethoxymethoxy group, methoxyethoxy group, ethoxyethoxy group, methoxypropoxy group, methoxybutoxy group, and ethoxybutoxy group. Examples of the alkoxyalkoxyalkoxy group having 3 to 15 carbon atoms include a methoxymethoxymethoxy group, a methoxymethoxyethoxy group, a methoxyethoxyethoxy group, and an ethoxyethoxyethoxy group. Examples of the aryloxy group having 6 to 12 carbon atoms include a phenoxy group, a tolyloxy group, a xylyloxy group, and a naphthyloxy group. Examples of the alkoxycarbonyl group having 2 to 7 carbon atoms include a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an isopropoxycarbonyl group, and an n-butoxycarbonyl group. Examples of the alkylcarbonyloxy group having 2 to 7 carbon atoms include a methylcarbonyloxy group, an ethylcarbonyloxy group, an n-propylcarbonyloxy group, and an n-butylcarbonyloxy group. Examples of the alkoxycarbonyloxy group having 2 to 7 carbon atoms include a methoxycarbonyloxy group, an ethoxycarbonyloxy group, an n-propoxycarbonyloxy group, and an n-butoxycarbonyloxy group.

  More specifically, examples of the cyclic alkyl group represented by the formula (2) include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a 4-methylcyclohexyl group, 4- Examples thereof include an ethylcyclohexyl group and a 4-propylcyclohexyl group. Examples of the alkylene group having a cyclic alkyl group represented by the above formula (3) include a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylpropyl group, and a 4-isopropylcyclohexylmethyl group. Among these, from the viewpoint of cost and ease of synthesis, a cyclohexylmethyl group, a cyclohexylethyl group, a 4-methylcyclohexyl group, a 4-ethylcyclohexyl group, a 4-propylcyclohexyl group, a cyclohexylpropyl group, or a 4-isopropylcyclohexylmethyl group Etc. are particularly preferred.

R _{1 to} R ₈ may all be any one of the above cyclic alkyl group and an alkylene group having a cyclic alkyl group, but some of R _{1 to} R ₈ may be the above cyclic alkyl group. Or an alkylene group having a cyclic alkyl group, and the remainder may be, for example, a branched or straight chain alkyl group. The number of carbon atoms of the branched or straight chain alkyl group is suitably 1-20. The linear alkyl group may have a substituent or may not have a substituent.

  Examples of the branched alkyl group include 1-methylethyl group (iso-propyl group), 1-methylpropyl group (sec-butyl group), 1,1-dimethylethyl group (tert-butyl group), 1 , 1-dimethylpropyl group, 1-methylbutyl group, 1,2-dimethylpropyl group, 1,2-dimethylbutyl group, 2-methylpropyl group (iso-butyl group), 2,2-dimethylpropyl group, 2- 1 to 20 carbon atoms such as methylbutyl group, 2-ethylbutyl group, 3-methylbutyl group (iso-amyl group), 1,1-dimethylbutyl group, 2,2-dimethylbutyl group, and 3,3-dimethylbutyl group These branched chain alkyl groups are exemplified. Of these, a branched alkyl group having 1 to 10 carbon atoms is preferable.

  Examples of the linear alkyl group include an ethyl group, an n-propyl group, and an n-butyl group. When these linear alkyl groups have a substituent, the substituent is the same as the substituent that (B) in Formula (2) and Formula (3) or (A) in Formula (3) has. . That is, as the substituent, a cyano group, a hydroxyl group, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, an alkoxyalkoxy group having 2 to 8 carbon atoms, an alkoxyalkoxyalkoxy group having 3 to 15 carbon atoms, an allyloxy group, Examples thereof include an aryloxy group having 6 to 12 carbon atoms, an alkoxycarbonyl group having 2 to 7 carbon atoms, an alkylcarbonyloxy group having 2 to 7 carbon atoms, and an alkoxycarbonyloxy group having 2 to 7 carbon atoms.

  Next, specific examples of the first diimonium salt compound of the present invention are shown in Table 1. However, the second diimonium salt compound of the present invention is not limited to the specific examples listed in Table 1.

In Table 1, when other than the 1,4-position of ring A is unsubstituted, it is abbreviated as “H”, and the same applies to ring B. When all of R _{1 to} R ₈ are cyclohexylmethyl, it is abbreviated as 8 (cyclohexylmethyl). When any four of R _{1 to} R ₈ are n-butyl and the remaining four are cyclohexylmethyl, they are abbreviated as 4 (n-butyl) and 4 (cyclohexylmethyl).

  The diimonium salt compound represented by the formula (1) of the present invention can be produced, for example, by the following method.

  First, an amino compound is obtained by a method described in, for example, US Pat. No. 3,251,881, US Pat. No. 3,575,871, Japanese Patent Application Laid-Open No. 61-69991. That is, first, as described in [Chemical Formula 3], p-phenylenediamine and 1-chloro-4-nitrobenzene are subjected to an Ullmann reaction and a reduction reaction to obtain an amino form. In [Chemical Formula 3], ring A and ring B are as defined above.

Next, for example, No. 1 in Table 1 above. In the case of obtaining a compound in which all the substituents of R _{1 to} R ₈ are the same as the compound (1) (all the same substituents), the organic solvent at 30 to 180 ° C., more preferably 50 to 150 ° C. The amino compound is dissolved, and 8 mol of a halogenated compound ((bromomethyl) cyclohexane) is reacted with 1 mol of the amino compound in an organic solvent. Thereby, all the same substitution products can be obtained. As the organic solvent, it is preferable to use a water-soluble polar solvent such as N, N-dimethylformamide, N, N-dimethylacetamide, or N-methylpyrrolidone.

When synthesizing compounds other than all the same substitution products, for example, No. 1 in Table 1 above is used. In the case of synthesizing the compound 3, the amino compound is dissolved in an organic solvent at 30 to 180 ° C., more preferably 50 to 150 ° C., and 4 mol of (bromomethyl) is added to 1 mol of the amino compound in the organic solvent. ) React cyclohexane. In this way, a cyclohexylmethyl group is introduced as four substituents among R _{1 to} R ₈ . Next, in order to introduce another substituent, 4 moles of 1-bromobutane are reacted with 1 mole of the amino compound in an organic solvent to obtain the remaining four substituents of R _{1 to} R _8. N-butyl is introduced. In the same manner as described above, any compound other than all the same substituents can be obtained.

  Next, the compound synthesized as described above is added to an organic solvent at 0 to 100 ° C., more preferably 20 to 100 ° C., together with an oxidizing agent (for example, a silver salt) corresponding to X in formula (1), Perform an oxidation reaction. As the organic solvent, it is preferable to use a water-soluble polar solvent such as tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, or N-methylpyrrolidone. When the equivalent of the oxidizing agent is 2 equivalents, the diimonium salt compound represented by the formula (1) is obtained.

  In addition to the method of reacting with the silver salt, the diimonium salt compound represented by the formula (1) can also be obtained by the following method.

  For example, a compound synthesized as described above (all the same substituted compound or any compound other than all the same substituted compound) in an organic solvent such as silver nitrate, silver perchlorate, cupric chloride, manganese dioxide, etc. Oxidize using an oxidizing agent. Salt exchange is performed by adding an acid or salt of a desired anion or an alkali of a desired cation to the obtained reaction solution. A diimonium salt compound can also be obtained by this method.

  The dimonium salt compound thus obtained has a maximum absorption wavelength of 900 nm or more, and an absorption coefficient as large as several tens of thousands to several hundreds of thousands. In addition to the use as a near-infrared absorbing compound contained in the near-infrared absorbing filter, such a compound is used as an anti-fading agent (singlet oxygen quencher) for optical recording media such as CD-R and DVD-R, a heat insulating film, Can be used for sunglasses.

(Embodiment 2)
In Embodiment 1, the second diimonium salt compound of the present invention will be described. The second diimonium salt compound of the present invention has a structure represented by the above formula (4).

In the formula (4), X is an anion necessary for neutralizing the charge. Examples of monovalent anions include chloride ions, bromide ions, iodide ions, perchlorate ions, nitrate ions, benzenesulfonate ions, p-toluenesulfonate ions, methyl sulfate ions, ethyl sulfate ions, and propyl sulfate. Ion, tetrafluoroborate ion, tetraphenylborate ion, hexafluorophosphate ion, benzenesulfonate ion, acetate ion, trifluoroacetate ion, propionacetate ion, benzoate ion, oxalate ion, succinate ion, malon Acid ion, oleate ion, stearate ion, citrate ion, diphosphate hydrogen ion, dihydrogen phosphate ion, pentachlorostannate ion, chlorosulfonate ion, fluorosulfonate ion, trifluoromethanesulfonate ion, hexa Fluoro Arsenate ion, hexafluoroantimonate ion, molybdate ion, tungstate ion, titanate ion, zirconate ion, bis (trifluoromethanesulfone) imidate ion, bis (pentafluoroethanesulfone) imidate ion, pentafluoroethane Examples include anions such as sulfone trifluoromethanesulfonimidate ion, trifluoromethanesulfone heptafluoropropanesulfonimidate ion, or nonafluorobutanesulfone trifluoromethanesulfonimidate ion. Of ^{_{these, (R f SO 2) -N}} - - (SO 2 R f ') (R f and R _f' is a fluoroalkyl group having 1 to 4 carbon atoms) anion represented by the, the near infrared absorption capacity It is preferable at a high point. Specifically, bis (trifluoromethanesulfone) imidate ion, bis (pentafluoroethanesulfone) imidate ion, and the like, in which R _f and R _f ′ are the same perfluoroalkyl group, are preferable.

  Examples of the divalent anion include naphthalene-1,5-disulfonic acid, R acid, G acid, H acid, benzoyl H acid, p-chlorobenzoyl H acid, p-toluenesulfonyl H acid, chloro H acid, chloro. Acetyl H acid, methanyl γ acid, 6-sulfonaphthyl-γ acid, C acid, ε acid, p-toluenesulfonyl R acid, naphthalene-1,6-disulfonic acid, 1-naphthol-4,8-disulfonic acid, etc. Naphthalene disulfonic acid derivative, carbonyl J acid, 4,4′-diaminostilbene-2,2′-disulfonic acid, diJ acid, naphthalic acid, naphthalene-2,3-dicarboxylic acid, diphenic acid, stilbene-4,4 '-Dicarboxylic acid, 6-sulfo-2-oxy-3-naphthoic acid, anthraquinone-1,8-disulfonic acid, 1,6-diaminoanthraquinone-2,7-disulfur Acid, 2- (4-sulfophenyl) -6-aminobenzotriazole-5-sulfonic acid, 6- (3-methyl-5-pyrazolonyl) -naphthalene-1,3-disulfonic acid, 1-naphthol-6 And divalent organic acid ions such as (4-amino-3-sulfo) anilino-3-sulfonic acid.

  At least one of ring A and four rings B may have 1 to 4 substituents other than the 1,4-position, or may not have a substituent. Examples of the substituent include at least one substituent selected from the group consisting of a lower alkyl group, a lower alkoxy group, a cyano group, a halogen atom, and a hydroxyl group. As a lower alkyl group, a C1-C5 alkyl group, such as a methyl group and an ethyl group, is mentioned, for example. As a lower alkoxy group, C1-C5 alkoxy groups, such as a methoxy group and an ethoxy group, are mentioned, for example. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  When at least one of the ring A and the four rings B has a substituent, the substituent is preferably a halogen atom (especially a chlorine atom or a bromine atom), a methyl group, or a cyano group.

  When all four rings B have a substituent, it is preferable that all the substituents are the same. In this case, the position of the substituent is preferably m-position with respect to the nitrogen atom bonded to the phenylenediamine skeleton, since it is easy to synthesize.

  It is preferable that the ring A and the four rings B have no substituent other than the 1,4-position, since a diimonium salt compound can be synthesized more easily.

At least one of R _{1 to} R ₈ is an alkoxyalkyl group. The alkoxyalkyl group may be either a linear alkoxyalkyl group or a branched alkoxyalkyl group. For example, methoxymethyl group, ethoxymethyl group, n-propoxymethyl group, 2-isopropoxymethyl group, isobutoxymethyl group, sec-butoxymethyl group, t-butoxymethyl group, pentyloxymethyl group, hexyloxymethyl group, 1-methoxyethyl group, 2-methoxyethyl group, 1-ethoxyethyl group, 2-ethoxyethyl group, 2-propoxyethyl group, 1-propoxyethyl group, 2-isopropoxyethyl group, 1-isopropoxyethyl group, 1-butoxyethyl group, 1- (sec-butoxy) ethyl group, 1- (t-butoxy) ethyl group, 1-isobutoxyethyl group, 2-butoxyethyl group, 2-isobutoxyethyl group, 2- (sec -Butoxy) ethyl group, 2- (t-butoxy) ethyl group, 3-ethoxypropyl group, 3-methoxy Propyl group, 2-methoxypropyl group, 1-methoxypropyl group, 2-ethoxypropyl group, 3-propoxypropyl group, 3-isopropoxypropyl group, 3- (t-butoxy) propyl group, 4-methoxybutyl group, 3-methoxybutyl group, 2-methoxybutyl group, 4-ethoxybutyl group, 3-ethoxybutyl group, 4-propoxybutyl group, 4- (t-butoxy) butyl group, 5-methoxypentyl group, 4-methoxypentyl group Group, 3-methoxypentyl group, 2-methoxypentyl group, 5-ethoxypentyl group, 4-ethoxypentyl group, 5-propoxypentyl group, 6-methoxyhexyl group, 6-ethoxyhexyl group, 6- (t-butoxy group) ) Hexyl group, 2-methoxy-1-methylethyl group, 2-ethoxy-1-methylethyl group, 2-methoxy 1-ethylethyl group, 2-butoxy-1-methylethyl group, 3-methoxy-2-methylpropyl group, 3-methoxy-1-methylpropyl group, 3-methyl-3-methoxybutyl group, tetrahydrofuranyl group, tetrahydro A pyranyl group etc. are mentioned. Of these, a 2-isopropoxyethyl group, a 2-isopropoxymethyl group, a 2-ethoxyethyl group, and a 2-propoxyethyl group are preferable because of their high near-infrared absorptivity.

All of R _{1 to} R ₈ may be the alkoxyalkyl group, but some of R _{1 to} R ₈ are the alkoxyalkyl groups, and the rest are, for example, branched or linear. It may be an alkyl group. The number of carbon atoms of the branched or straight chain alkyl group is suitably 1-20. Furthermore, the branched or straight chain alkyl group may have a substituent or may not have a substituent.

  Examples of the branched alkyl group include 1-methylethyl group (iso-propyl group), 1-methylpropyl group (sec-butyl group), 1,1-dimethylethyl group (t-butyl group), 1 , 1-dimethylpropyl group, 1-methylbutyl group, 1,2-dimethylpropyl group, 1,2-dimethylbutyl group, 2-methylpropyl group (iso-butyl group), 2,2-dimethylpropyl group, 2- 1 to 20 carbon atoms such as methylbutyl group, 2-ethylbutyl group, 3-methylbutyl group (iso-amyl group), 1,1-dimethylbutyl group, 2,2-dimethylbutyl group, and 3,3-dimethylbutyl group These branched chain alkyl groups are exemplified. Of these, a branched alkyl group having 1 to 10 carbon atoms is preferable.

  As said linear alkyl group, an ethyl group, n-propyl group, or n-butyl group etc. are mentioned, for example.

  When these branched alkyl groups or linear alkyl groups have a substituent, the substituent is a cyano group, a hydroxyl group, a halogen atom, an alkoxyalkoxy group having 2 to 8 carbon atoms, or a 3 to 15 carbon atoms. Examples include an alkoxyalkoxyalkoxy group, an aryloxy group having 6 to 12 carbon atoms, an alkoxycarbonyl group having 2 to 7 carbon atoms, an alkylcarbonyloxy group having 2 to 7 carbon atoms, or an alkoxycarbonyloxy group having 2 to 7 carbon atoms. .

  Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom. Examples of the alkoxyalkoxy group having 2 to 8 carbon atoms include methoxymethoxy group, ethoxymethoxy group, methoxyethoxy group, ethoxyethoxy group, methoxypropoxy group, methoxybutoxy group, and ethoxybutoxy group. Examples of the alkoxyalkoxyalkoxy group having 3 to 15 carbon atoms include a methoxymethoxymethoxy group, a methoxymethoxyethoxy group, a methoxyethoxyethoxy group, and an ethoxyethoxyethoxy group. Examples of the aryloxy group having 6 to 12 carbon atoms include a phenoxy group, a tolyloxy group, a xylyloxy group, and a naphthyloxy group. Examples of the alkoxycarbonyl group having 2 to 7 carbon atoms include a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an isopropoxycarbonyl group, and an n-butoxycarbonyl group. Examples of the alkylcarbonyloxy group having 2 to 7 carbon atoms include a methylcarbonyloxy group, an ethylcarbonyloxy group, an n-propylcarbonyloxy group, and an n-butylcarbonyloxy group. Examples of the alkoxycarbonyloxy group having 2 to 7 carbon atoms include a methoxycarbonyloxy group, an ethoxycarbonyloxy group, an n-propoxycarbonyloxy group, and an n-butoxycarbonyloxy group.

  Next, specific examples of the second diimonium salt compound of the present invention are shown in Table 2. However, the second diimonium salt compound of the present invention is not limited to the specific examples listed in Table 2.

In Table 2, when other than the 1,4-position of ring A is unsubstituted, it is abbreviated as “H”, and the same applies to ring B. When all of R _{1 to} R ₈ are 2-isopropoxyethyl, it is abbreviated as 8 (2-isopropoxyethyl). When any four of R _{1 to} R ₈ are 2-isopropoxyethyl and the remaining four are n-butyl, they are abbreviated as 4 (2-isopropoxyethyl), 4 (n-butyl). ing.

  The diimonium salt compound represented by the formula (4) of the present invention can be produced, for example, by the following method.

  First, for example, an amino compound is obtained by a method described in US Pat. No. 3,251,881, US Pat. No. 3,575,871, Japanese Patent Application Laid-Open No. 61-69991, and the like. That is, first, as described in the above [Chemical Formula 3], p-phenylenediamine and 1-chloro-4-nitrobenzene are subjected to an Ullmann reaction and a reduction reaction to obtain an amino form. In [Chemical Formula 3], ring A and ring B are as defined above.

Next, for example, No. 2 in Table 2 above. In the case of obtaining a compound in which all the substituents of R _{1 to} R ₈ are the same (all identical substituents), such as the compound of 13, the organic solvent at 30 to 180 ° C., more preferably 50 to 150 ° C. is used. The amino compound is dissolved, and 8 mol of a halogenated compound (2-isopropoxyethyl bromide) is reacted with 1 mol of the amino compound in an organic solvent. Thereby, all the same substitution products can be obtained. As the organic solvent, a water-soluble polar solvent such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone is preferably used.

When synthesizing a compound other than all the same substitutes, for example, No. in Table 2 above is used. In the case of synthesizing 14 compounds, the amino compound is dissolved in a water-soluble polar solvent at 30 to 180 ° C., more preferably 50 to 150 ° C., and in this solvent, 4 amino acids are added to 1 mol of the amino compound. Mole 2-isopropoxyethyl bromide is reacted. In this way, a 2-isopropoxyethyl group is introduced as four substituents among R _{1 to} R ₈ . Next, in order to introduce another substituent, 4 moles of 1-bromobutane are reacted with 1 mole of the amino compound in the above solvent to obtain the remaining four substituents of R _{1 to} R _8. N-butyl is introduced. In the same manner as described above, any compound other than all the same substituents can be obtained.

  Next, the compound synthesized as described above is added to an organic solvent at 0 to 100 ° C., more preferably 20 to 100 ° C., together with an oxidizing agent (for example, a silver salt) corresponding to X in formula (1), Perform an oxidation reaction. As the organic solvent, a water-soluble polar solvent such as tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone or the like is preferably used. When the equivalent of the oxidizing agent is 2 equivalents, the diimonium salt compound represented by the formula (1) is obtained.

  In addition to the method of reacting with the silver salt, the following method can also obtain the diimonium salt compound represented by the formula (4).

  For example, oxidation of silver nitrate, silver perchlorate, cupric chloride, manganese dioxide, etc. in an organic solvent with the compound synthesized as described above (all the same substituted compounds or any compound other than all the same substituted compounds) Oxidize with agent. Salt exchange is performed by adding an acid or salt of a desired anion or an alkali of a desired cation to the obtained reaction solution. A diimonium salt compound can also be obtained by this method.

  The dimonium salt compound thus obtained has a maximum absorption wavelength of 900 nm or more and a large extinction coefficient of about several tens of thousands to several hundreds of thousands. Furthermore, since the diimonium salt compound of this embodiment has an alkoxyalkyl group in the structure, the solubility in a solvent is high. In addition to the use as a near-infrared absorbing compound contained in the near-infrared absorbing filter, such a compound is used as an anti-fading agent (singlet oxygen quencher) for optical recording media such as CD-R and DVD-R, a heat insulating film, Can be used for sunglasses.

(Embodiment 3)
In Embodiment 3, an example of a near-infrared absorption filter using the diimonium salt compound of Embodiment 1 will be described.

  As shown in FIG. 1, the near-infrared absorbing film of the present embodiment includes a base 1 and a near-infrared absorbing layer 2 disposed on one main surface of the base 1. Since the near-infrared absorbing film of this embodiment uses the diimonium salt compound of Embodiment 1 that is not easily adversely affected by heat and humidity, the near-infrared absorbing ability is prevented from decreasing over time.

  The material of the base material 1 is not particularly limited as long as it is a material having translucency with respect to visible light. For example, a resin such as a saturated polyester resin, a polycarbonate resin, a polyacrylate resin, an alicyclic polyolefin resin, a polystyrene resin, a polyvinyl chloride resin, or a polyvinyl acetate resin is formed into a film or sheet. What was processed can be used.

  Examples of methods for processing the resin into a film or sheet include extrusion molding, calender molding, compression molding, injection molding, and a method in which the resin is dissolved in a solvent and cast. The thickness of the base material 1 is usually about 10 μm to 500 μm. The resin may contain additives such as an antioxidant, a flame retardant, a heat resistance inhibitor, an ultraviolet absorber, a surface conditioner, a lubricant, and an antistatic agent.

  The near-infrared absorbing layer 2 can be formed by applying a paint obtained by adding a near-infrared absorbing composition containing the near-infrared absorbing compound of Embodiment 1 and a resin as a binder to a solvent to a substrate. .

  The near-infrared absorbing compound contained in the near-infrared absorbing composition may be only the near-infrared absorbing compound (diimonium salt compound) of Embodiment 1, but another near-infrared absorbing compound of Embodiment 1 having a different maximum absorption wavelength. It is preferable that an infrared absorbing compound is also included. As described above, when two or more kinds of near-infrared absorbing compounds having different maximum absorption wavelengths are used, it is wider in the near-infrared wavelength region (850 nm to 1100 nm) than when one kind of near-infrared absorbing compound is used. This is because light in the wavelength range can be absorbed. It is more preferable that the near-infrared absorbing composition contains two or more kinds of near-infrared absorbing compounds having different maximum absorption wavelengths so that almost all light in the near-infrared wavelength region (850 nm to 1100 nm) can be absorbed. What is necessary is just to determine suitably the mixture ratio of 2 or more types of near-infrared absorption compounds according to the near-infrared absorption wavelength range etc. of each near-infrared absorption compound.

  As another near-infrared absorbing compound having a maximum absorption wavelength different from that of the near-infrared absorbing compound of Embodiment 1, cyanine dyes (ion binding compounds), phthalocyanine dyes (metal complex compounds), azo dyes, squarylium dyes And at least one dye selected from the group consisting of dithiol dyes.

  Examples of the combination of two or more near-infrared absorbing compounds include the diimonium compound / cyanine dye of Embodiment 1 and the diimonium salt compound / phthalocyanine dye of Embodiment 1.

  The binder resin contained in the near-infrared absorbing composition is not particularly limited as long as it has translucency to visible light, but acrylic resin, polyurethane resin, polyvinyl chloride resin, epoxy resin, polyvinyl acetate Resin, polystyrene resin, cellulose resin, polybutyral resin, polyester resin, or the like can be used. One of these resins may be used, or a polymer blend in which two or more are blended may be used. In particular, it is preferable to use a resin having a glass transition temperature of 80 ° C. or higher because the compatibility with the near-infrared absorbing compound is good.

  Although there is no restriction | limiting in particular about the mixture ratio of binder resin contained in a near-infrared absorption composition, It is preferable in it being about 1000-2000 weight part with respect to 100 weight part of near-infrared absorption compounds.

  If necessary, additives such as an antioxidant, a flame retardant, a heat resistance inhibitor, an ultraviolet absorber, a surface conditioner, a lubricant, and an antistatic agent may be added to the near-infrared absorbing composition.

  The solvent that is contained in the paint and dissolves the near-infrared absorbing compound and the binder resin is not particularly limited, but is an organic solvent such as methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, tetrahydrofuran, acetonitrile, and propionitrile, or a mixture thereof. A solvent is mentioned.

  In the present application, “dissolution of near-infrared absorbing compound” means that the near-infrared absorbing compound dissolves in the solvent and does not have a solid shape, and becomes an ion pair or complex state. It is distinguished from “dissociation”, which means a state in which it is dissolved in a solvent to the extent that it does not.

  There are no particular restrictions on the coating method, but for example, coating methods such as roll coating, die coating, air knife coating, blade coating, spin coating, reverse coating, gravure coating, gravure printing, screen printing, offset printing, inkjet printing, etc. The printing method can be used.

  The near-infrared absorption filter of the present embodiment preferably has a Haze value (defined in JIS K7105) of 1% or less. This is because, when the Haze value is 1% or less, for example, when the near-infrared absorption filter is used as a constituent member of the front plate of the PDP, the vividness of the image is not impaired. The Haze value is also called a haze value, and is a value representing the degree of haze inside or on the surface of the plastic. The lower the value, the better.

  The spectral transmittance of the near infrared absorption filter in the wavelength region 850 nm to 1100 nm is preferably 15% or less, and more preferably 10% or less. If the spectral transmittance is within this range, the malfunction of the electronic device can be sufficiently suppressed by the near infrared absorption filter. The spectral transmittance is preferably as low as possible.

  The thickness of the near infrared absorption layer 2 is preferably 2 μm or more and 15 μm or less, and more preferably 3 μm or more and 10 μm or less. When the thickness of the near-infrared absorbing layer 2 is less than 2 μm, it is necessary to increase the amount of the near-infrared absorbing compound added to the binder resin in order to make the spectral transmittance in the wavelength region 850 nm to 1100 nm 15% or less. In this case, light scattering due to the undissolved near-infrared absorbing compound occurs, and as a result, there may be a problem that the Haze value increases. When the thickness of the near infrared absorption layer 2 exceeds 15 μm, although the spectral transmittance in the wavelength region 850 nm to 1100 nm can be maintained at 15% or less, a free solvent may remain in the near infrared absorption layer 2. This residual solvent causes redissolution or dissociation of the near-infrared absorbing compound and causes deterioration of the near-infrared absorption characteristics with time. If the thickness of the near-infrared absorbing layer 2 is 2 μm or more and 15 μm or less, the residual solvent can be suitably suppressed.

  The example of the near infrared absorption filter of the present embodiment has been described above by taking the near infrared absorption filter shown in FIG. 1 as an example, but the structure of the near infrared absorption filter of the present embodiment is limited to the example shown in FIG. Not. The near-infrared absorbing filter of this embodiment may be composed of a single layer in which a near-infrared absorbing compound is dispersed in a resin. Moreover, as shown in FIG. 2, the near-infrared absorption filter may be provided with the antireflection layer 4 arrange | positioned on the opposite side to the near-infrared absorption layer 2 side of the base material 1, and the base material 1 and antireflection A hard coat layer 3 disposed between the layers 4 may be provided. The hard coat layer 3 includes, for example, a thermosetting resin or inorganic fine particles. The antireflection layer 4 may be composed of three films having different refractive indexes. In this case, the three films are a medium refractive index film 4a, a high refractive index film 4b, and a low refractive index from the hard coat layer 3 side. The films 4c are arranged in this order.

  The diimonium salt compound of Embodiment 1 contained in the said near-infrared absorption filter is not limited to 1 type, Two or more types may be sufficient. Moreover, in the said near-infrared absorption filter, although the diimonium salt compound of Embodiment 1 is used, it may replace with this and may use the 1 or more types of diimonium salt compound of Embodiment 2. FIG. Since the diimonium salt compound of Embodiment 2 is also less susceptible to adverse effects due to heat and humidity, it is possible to provide a near-infrared absorption filter in which the near-infrared absorption ability is suppressed from decreasing with time. The near-infrared absorption filter may include both the diimonium salt compound of the first embodiment and the diimonium salt compound of the second embodiment.

(Embodiment 4)
In Embodiment 4, an example of the display front plate of the present invention will be described. As shown in FIG. 3, the display front plate 11 of the present embodiment includes a substrate 12, a near-infrared absorption filter 13 disposed on one main surface side of the substrate 12, and the other main surface side of the substrate 12. The electromagnetic wave shielding layer 14 and the electrode (earth) 15 are arranged.

  The material of the board | substrate 12 will not be specifically limited if it is a material which has translucency with respect to visible light, For example, a tempered glass etc. can be used. As the near-infrared absorption filter 13, for example, the near-infrared absorption filter of Embodiment 3 can be used.

  Since the near-infrared absorption filter of Embodiment 3 is used for the display front plate of this embodiment, the deterioration with time of near-infrared absorption characteristics under high temperature and high humidity use conditions is suppressed.

  Hereinafter, based on an Example, this invention is demonstrated more concretely. In addition, this invention is not limited to a following example.

Example 1
Prepare 10.8 parts by weight of p-phenylenediamine, 94.5 parts by weight of p-nitrochlorobenzene, 34.5 parts by weight of anhydrous potassium carbonate, and 2 parts by weight of copper powder, and stir these in 150 parts by weight of dimethylformamide. Refluxed under. Refluxing was performed for 15 hours. After this reaction, the reaction mixture was filtered, and the filtrate was thoroughly washed with dimethylformamide, water and acetone, then dried and reddish brown N, N, N ′, N′-tetrakis (p-nitrophenyl) -p -30 weight part of phenylenediamine was obtained.

Next, in an autoclave, 25 parts by weight of N, N, N ′, N′-tetrakis (p-nitrophenyl) -p-phenylenediamine is combined with 1 part by weight of a palladium-carbon hydrogenation catalyst and 100 parts by weight of dimethylformamide. Added inside. At that time, the mixture was stirred at 90 ° C. to 100 ° C. until hydrogen absorption stopped while applying a hydrogen gas pressure of 5.0 kg / cm ² . The reaction solution thus obtained was filtered, and then the filtrate was placed in 350 parts by weight of ice water and stirred for a while, and then the precipitate was filtered. Thereafter, the precipitate was recrystallized in a mixed solvent of ethanol-dimethylformamide (volume ratio 5: 7), and 14 weight of N, N, N ′, N′-tetrakis (p-aminophenyl) -p-phenylenediamine was obtained. I got a part. By liquid chromatography analysis, the purity of N, N, N ′, N′-tetrakis (p-aminophenyl) -p-phenylenediamine was 95.8%. As a result of nuclear magnetic resonance spectrum (d ₆ -DMSO) analysis, the NMR chart shows that the absorption of the amino group of 8H at δ3.35ppm is a 20H minute aromatic ring of a doublet broad at δ6.40 to 6.51ppm. Absorption was observed.

  3.8 parts of the above amino compound, 30 parts by weight of N, N′-dimethylformamide (DMF), 15 parts by weight of potassium carbonate, and 12.8 parts by weight of bromomethylcyclohexane were prepared, and these were stirred at 120 to 140 ° C. for 8 hours. . Then, after cooling, the precipitated crystals are filtered, washed with water, dried, recrystallized using tetrahydrofuran (THF), and N, N, N ′, N′-tetrakis [p-di (cyclohexylmethyl) amino. 2.01 parts by weight of phenyl] -p-phenylenediamine were obtained.

  1 part by weight of N, N, N ′, N′-tetrakis [p-di (cyclohexylmethyl) aminophenyl] -p-phenylenediamine is added to 10 parts by weight of THF, and at 70 ° C., 10 parts by weight of DMF is added thereto. Dissolved silver hexafluorophosphate was further added. The number of moles of silver hexafluorophosphate was twice that of N, N, N ′, N′-tetrakis [p-di (cyclohexylmethyl) aminophenyl] -p-phenylenediamine. These were reacted for 1 hour, and the precipitated silver was filtered off. 5 parts by weight of water was added to the filtrate, and the precipitated crystals were collected by filtration and dried. 0.98 parts by weight of compound 1 were obtained. No. The compound 1 had a maximum absorption wavelength of 1092 nm and was a compound having a large absorption region with respect to light in the near infrared region.

(Example 2)
A compound No. 2 in Table 1 was obtained in the same manner as in Example 1 except that silver hexafluoroantimonate was used instead of silver hexafluorophosphate.

(Example 3)
A compound No. 7 in Table 1 was obtained in the same manner as in Example 1 except that 1-bromo-2-cyclohexylethane was used instead of bromomethylcyclohexane.

Example 4
A compound No. 8 in Table 1 was obtained in the same manner as in Example 3 except that silver hexafluoroantimonate was used instead of silver hexafluorophosphate.

(Example 5)
3.8 parts by weight of N, N, N ′, N′-tetrakis (p-aminophenyl) -p-phenylenediamine, 30 parts by weight of DMF, 15 parts by weight of potassium carbonate, and 13.4 parts by weight of isopropoxyethyl bromide are prepared. These were stirred at 100 to 130 ° C. for 8 hours. Next, the obtained reaction solution was placed in 100 parts by weight of ice water and stirred, and then the precipitate was collected by filtration. The precipitate collected by filtration was dried and purified using a silica gel column, and N, N, N ′, N′-tetrakis [p-di (isopropoxyethyl) aminophenyl] -p-phenylenediamine 3.53 wt. Got a part.

  1 part by weight of N, N, N ′, N′-tetrakis [p-di (isopropoxyethyl) aminophenyl] -p-phenylenediamine is added to 10 parts by weight of DMF, and 10 parts by weight of DMF is added thereto while stirring at 70 ° C. Further, bis (trifluoromethanesulfone) imidate silver dissolved in was added. The number of moles of silver bis (trifluoromethanesulfone) imidate was twice that of N, N, N ′, N′-tetrakis [p-di (isopropoxyethyl) aminophenyl] -p-phenylenediamine. After reacting these for 1 hour, the precipitated silver was filtered off. 10 parts by weight of water was added to the filtrate, and the precipitated crystals were collected by filtration and dried. 0.76 parts by weight of 13 compounds were obtained. The absorption maximum wavelength of the compound of No. 13 was 1068 nm, and the compound of No. 13 was a compound which showed a large absorption with respect to light in the near infrared region.

(Example 6)
A compound of No. 15 in Table 1 was obtained in the same manner as in Example 5 except that isopropoxymethyl bromide was used instead of isopropoxyethyl bromide.

  The compound No.1, No.2, No.7, No.8, No.13, No.15 obtained as described above with respect to 100 parts by weight of polymethyl methacrylate (PMMA) is 7.25. 233 parts by weight of methyl ethyl ketone was further added as a solvent, and a paint for forming a near-infrared absorbing layer was obtained. This paint was applied to a substrate using a micro gravure coater, and the applied paint was dried to obtain a near infrared absorption filter. The coating of the paint was performed so that the film thickness after drying was 4 μm. As a base material, a polyethylene terephthalate (PET) film (“U-34” manufactured by Toray Industries, Inc.) having a thickness of 100 μm and subjected to easy adhesion treatment on both front and back surfaces was used.

(Comparative Example 1)
N, N, N ′, N′-tetrakis [p-di (n-butyl) aminophenyl] -p in the same manner as in Example 1 except that n-butyl bromide was used instead of bromomethylcyclohexane. -Phenylenediamine was obtained. Next, in the same manner as in Example 2, this compound was reacted with silver hexafluoroantimonate to obtain a diimonium salt compound having a linear alkyl group. Moreover, the near-infrared absorption filter was obtained like Example 1 using the diimonium salt compound which has a linear alkyl group.

(Comparative Example 2)
N, N, N ′, N′-tetrakis [p-di (iso-butyl) aminophenyl] -p in the same manner as in Example 1 except that iso-butyl bromide was used instead of bromomethylcyclohexane. -Phenylenediamine was obtained. Next, in the same manner as in Example 1, this compound was reacted with silver hexafluorophosphate to obtain a diimonium salt compound having a branched alkyl group. Moreover, the near-infrared absorption filter was obtained like the Example using the diimonium salt compound which has a branched alkyl group.

(Moisture and heat resistance test)
The near-infrared absorption filters of Examples 1 to 6 and Comparative Examples 1 and 2 were tested for storage for 48 hours at a temperature of 80 ° C. and a humidity of 95%, and the spectral transmittance before and after this test was measured using a spectrophotometer (manufactured by JASCO) U-Best V-570 "). And the change rate of the transmittance | permeability of a specific wavelength was computed. The resulting transmittance change rate was evaluated according to the following criteria, and the results are shown in Table 3.

〔Evaluation criteria〕
A: Change in transmittance before and after test is less than 0.5% B: Change in transmittance before and after test is 0.5% or more and less than 1.5% Δ: Change in transmittance before and after test is 1.5% or more and 3.0 Less than% ×: The change in transmittance before and after the test is 3.0% or more

  As shown in Table 3, the near-infrared absorption filters of Examples 1 to 4 using a diimonium salt compound having a cyclic alkyl group or an alkylene group having a cyclic alkyl group are diimonium salt compounds having a linear alkyl group. It is confirmed that the degree of deterioration of the near-infrared absorptivity after the wet heat resistance test is smaller than that of the near-infrared absorption filter of Comparative Example 1 using a diamonium salt compound having a branched alkyl group and Comparative Example 2 did it.

  Further, it was confirmed that when the anion constituting the diimonium salt compound was a hexafluorophosphate ion, the deterioration of the near-infrared absorption ability after the wet heat resistance test was very small.

  In addition, as shown in Table 3, the near-infrared absorption filters of Examples 5 and 6 using a diimonium salt compound having an alkoxyalkyl group are also more resistant to heat and humidity than the near-infrared absorption filters of Comparative Example 1 and Comparative Example 2. It was confirmed that the transmittance change before and after the test was small, particularly in the short wavelength region, and the degree of deterioration of the near infrared ray absorbing ability was small.

  Since the diimonium salt compound of the present invention has excellent heat resistance and moisture resistance, it can be used in various applications. For example, it can be used for a PDP display front plate, automobile glass, a near infrared absorption filter for building materials, and the like, and is particularly useful as a near infrared absorption filter for a PDP display front plate. The diimonium salt compound of the present invention can also be used as a dye used for optical recording media such as CD-R and DVD-R.

It is sectional drawing which shows an example of the near-infrared absorption filter of this embodiment. It is sectional drawing which shows the other example of the near-infrared absorption filter of this embodiment. It is sectional drawing which shows an example of the front plate for a display of this embodiment.

Claims (13)

A diimonium salt compound having a structure represented by the following formula (1):

However, in the formula (1), X is hexafluorophosphate ion, other than 1,4-position of ring A and ring B are all unsubstituted, R ₁ to R ₈ are cyclohexylmethyl group Or it is a cyclohexylethyl group .   The near-infrared absorption composition containing the diimonium salt compound of Claim 1, and resin.   The near-infrared absorbing composition according to claim 2, further comprising at least one dye selected from the group consisting of a cyanine dye, a phthalocyanine dye, an azo dye, a squarylium dye, and a dithiol dye.   The near-infrared absorption filter containing the diimonium salt compound of Claim 1.   The near-infrared absorption filter according to claim 4, further comprising at least one dye selected from the group consisting of a cyanine dye, a phthalocyanine dye, an azo dye, a squarylium dye, and a dithiol dye. Comprising a base material, and a near-infrared absorbing layer disposed on one main surface side of the base material,
The near-infrared absorption layer includes the diimonium salt compound according to claim 1.   The near-infrared absorption filter according to claim 6, further comprising an antireflection layer disposed on the opposite side of the main surface of the base material on the near-infrared absorption layer side.   The near-infrared absorption filter according to claim 7, further comprising a hard coat layer disposed between the base material and the antireflection layer.   A display front plate comprising the near-infrared absorbing filter according to claim 4.   A display front plate comprising the near-infrared absorbing filter according to claim 5.   A front plate for a display comprising the near-infrared absorbing filter according to claim 6.   A display front plate comprising the near-infrared absorbing filter according to claim 7.   A display front plate comprising the near-infrared absorbing filter according to claim 8.

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