JP6959794B2 - Squalilium compound - Google Patents

Description

The present invention relates to a squarylium compound, a resin composition containing the same, a cured product thereof, and an optical filter or sensor formed from the compound.

The squarylium compound is useful as a dye having an absorption region in the red to near infrared region, and various types of squarylium compounds have been known so far. For example, Patent Documents 1 to 3 disclose a squalylium compound having a structure in which benzene rings are bonded to both sides of the squalylium skeleton, and Patent Documents 4 and 5 have heterocycles bonded to both sides of the squalylium skeleton via carbon atoms. A squarylium compound having the above-mentioned structure is disclosed. Patent Document 6 discloses a squarylium compound having a structure in which a heterocycle is bonded to both sides of a squarylium skeleton via a carbon atom, and the carbon atom and the carbon atom constituting the heterocycle form a hydrocarbon ring. There is.

International Publication No. 2014/088063 Japanese Unexamined Patent Publication No. 2012-008532 Japanese Unexamined Patent Publication No. 2015-08637 Japanese Unexamined Patent Publication No. 2008-308602 Japanese Unexamined Patent Publication No. 2014-148567 Japanese Unexamined Patent Publication No. 2016-0746949

Squalylium compounds are expected to be used in near-infrared light cut filters, near-infrared absorbing films, security inks, etc. by utilizing the property of having an absorption region in the red to near-infrared region. When the squarylium compound is applied to such an application, it is desirable that the squarylium compound is dissolved in an organic solvent, a resin or the like and handled, whereby the handleability of the squarylium compound can be improved and the processability can be improved. However, the squarylium compound generally has low solubility in an organic solvent or a resin, and in order to exhibit the spectral characteristics derived from the squarylium compound, for example, when forming an optical filter from a resin composition containing the squarylium compound, optics are used. It is necessary to form the thickness of the filter to some extent. On the other hand, since electronic devices such as optical filters are required to be smaller and thinner, it is necessary to have a squarylium compound present in a higher concentration in the optical filter in order to form a thinner optical filter. Become. Also, when a squarylium compound is used in the security ink, it is preferable that the squarylium compound is contained in the ink in a high concentration in order to enhance the color development property of the ink.

The present invention has been made in view of the above circumstances, and an object of the present invention is to have excellent solubility in an organic solvent and to transmit light in the visible light region with high transmittance when a cured resin product is obtained. It is an object of the present invention to provide a squarylium compound capable of selectively absorbing light in the red to near infrared region.

The present invention includes the following inventions.
[1] A squarylium compound represented by the following formula (1).

[In equation (1),
R ¹ and R ⁶ each independently represent a branched alkyl group having 3 or more carbon atoms which may have a substituent.
R ² and R ⁷ each independently represent a linear alkyl group having 5 or more carbon atoms which may have a substituent.
R ³ , R ⁴ , R ⁸ and R ⁹ independently represent a hydrogen atom, an organic group or a polar functional group, respectively.
Rings A and B each independently represent a 5-membered or more nitrogen-containing heterocycle, and the nitrogen-containing heterocycle may have a substituent other than ^{R 1} and R ^6. ]
[2] The squarylium compound according to [1] represented by the following formula (2).

[In equation (2),
R ^{1 to} R ⁴ and R ^{6 to} R ⁹ have the same meaning as above.
R ⁵ is a hydrogen atom bonded to the carbon atoms constituting the ring A, an alkyl group, an aryl group, an aralkyl group or a halogenoalkyl group, a plurality of R ⁵ may be the being the same or different,
R ¹⁰ represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a halogenoalkyl group bonded to a carbon atom constituting ring B, and a plurality of R ^10s may be the same or different from each other.
m and n represent integers of 1 or more. ]

[3] The R ³ , R ⁴ , R ⁸ and R ⁹ independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, an amide group or a hydroxyl group, respectively, in [1] or [2]. The squarylium compound described.
[4] The absorption spectrum of a solution obtained by diluting a filtrate obtained by filtering a solution containing 1 part by mass of a squarylium compound and 99 parts by mass of toluene with a filter having a pore size of 0.45 μm with toluene by a factor of 2500 is in the wavelength range of 450 nm to 1100 nm. The squarylium compound according to any one of [1] to [3], which has a maximum absorbance of 1.0 or more.
[5] A resin composition comprising the squarylium compound according to any one of [1] to [4] and a resin component.
[6] A cured product obtained by curing the resin composition according to [5].
[7] An optical filter comprising the resin composition according to [5] or the cured product according to [6].
[8] A sensor comprising the optical filter according to [7].

The squarylium compound of the present invention has excellent solubility in an organic solvent, and when it is made into a cured product of a resin composition containing it, it transmits light in the visible light region with high transmittance and is red to red. It is possible to selectively absorb light in the near infrared region.

The absorption spectrum of the cured resin product containing the squarylium compound B examined in the examples is shown. The absorption spectrum of the cured resin product containing the comparative squarylium compound B examined in the examples is shown.

The squarylium compound of the present invention is represented by the following formula (1). In the following formula (1), R ¹ and R ⁶ each independently represent a branched alkyl group having 3 or more carbon atoms which may have a substituent, and R ² and R ⁷ are independent of each other. It represents a linear alkyl group having 5 or more carbon atoms which may have a substituent, and R ³ , R ⁴ , R ⁸ and R ⁹ independently represent a hydrogen atom, an organic group or a polar functional group. , Ring A and Ring B each independently represent a 5-membered or more nitrogen-containing heterocycle, and the nitrogen-containing heterocycle may have a substituent other than ^{R 1} and R ^6.

The squarylium compound represented by the formula (1) has excellent solubility in an organic solvent or a resin. Therefore, it becomes possible to contain the squarylium compound in a high concentration in the resin composition, and even if the thickness is thinly formed, such as when forming an optical filter from the resin composition, the squarylium compound is derived from red to red. Light in the near-infrared region can be suitably absorbed. Further, when the squarylium compound is used in the security ink, the squarylium compound can be contained in the ink at a high concentration, and the color development property of the ink can be enhanced. The squarylium compound represented by the formula (1) also selects light in the red to near infrared region while transmitting light in the visible light region with high transmittance according to the original absorption spectrum of the squarylium compound even in the cured resin product. It becomes possible to absorb the light.

A compound having a resonance relationship may be present in the squarylium compound. Examples of the compound having a resonance relationship with the squarylium compound of the formula (1) include compounds represented by the following formulas (1a) and (1b). The squarylium compound of the present invention is assumed to contain all of these compounds having a resonance relationship. Specifically, the squarylium compound of the formula (1) has a resonance relationship as represented by the following formulas (1a) and (1b). Contains the compounds found in.

In formula (1), the groups bonded to one side and the other side of the squarylium skeleton may be the same or different from each other. That is, R ¹ , R ² , R ³ , R ⁴ and ring A may be the same as or different from ring ^{R 6} , R ⁷ , R ⁸ , R ^{9 and ring B, respectively.} When the groups bonded to one side and the other side of the squarylium skeleton are the same, improvement in the durability of the squarylium compound against heat and light can be expected. When the groups bonded to one side and the other side of the squarylium skeleton are different from each other, the association and aggregation of the molecules of the squarylium compound are suppressed, and improvement in solubility in a solvent or resin can be expected.

The squarylium compound represented by the formula (1) has R ¹ , R ² , R ⁶ and R ⁷ as alkyl groups, and tends to become more soluble in organic solvents and resins as the number of carbon atoms increases. At that time, by using R ¹ and R ⁶ as branched alkyl groups, the solubility of the squarylium compound in an organic solvent or resin can be effectively enhanced. In addition, the squarylium compound originally has a spectral characteristic of selectively absorbing light in the red to near-infrared region and transmitting light in the visible light region with high transmittance, but R ¹ and R ⁶ are linear. ^{In the case of an alkyl group, R 1} and R ⁶ are branched alkyl groups where the squarylium compound may show a new absorption peak in the visible light region (for example, in the wavelength range of 500 nm to 600 nm) in the cured resin product. If so, such a concern becomes unnecessary, and light in the visible light region can be transmitted with high transmittance even in the cured resin product. On the other hand, if R ² and R ⁷ are linear alkyl groups, the heat resistance of the squarylium compound tends to increase, and the squarylium compound is decomposed when the squarylium compound is mixed with a resin and heat-molded or heat-cured. It can be suppressed. Therefore, the squarylium compound can be present in a high concentration even in the cured resin product that has undergone the heat treatment.

Since ^{the alkyl groups of R 1} and R ⁶ are branched, the number of carbon atoms (the number of carbon atoms excluding the substituent) is 3 or more. The upper limit of the number of carbon atoms of the branched alkyl groups of R ¹ and R ⁶ is not particularly limited, but is preferably 20 or less, more preferably 12 or less, further preferably 8 or less, and even more preferably 6 or less. The branched alkyl groups of R ¹ and R ⁶ include isopropyl group, isobutyl group, tert-butyl group, isopentyl group, sec-pentyl group, 1-ethylpropyl group, neopentyl group, tert-pentyl group, isohexyl group and sec. -Hexyl group, 2-methylpentyl group, 3-methylpentyl group, tert-hexyl group, 2-ethylhexyl group and the like can be mentioned.

The ^{number of carbon atoms (the number of carbon atoms excluding substituents) of the linear alkyl groups of R 2} and R ⁷ is 5 or more, preferably 6 or more, and 7 or more from the viewpoint of ensuring solubility in an organic solvent or resin. More preferably, 8 or more is further preferable. The upper limit of the number of carbon atoms of the linear alkyl groups of R ² and R ⁷ is not particularly limited, but is preferably 30 or less, more preferably 25 or less, further preferably 20 or less, and even more preferably 18 or less. The ^{linear alkyl groups of R 2} and R ⁷ include n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group and n. -Dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecil group, n-icosyl group and the like can be mentioned.

The branched alkyl group of R ¹ and R ^{6 and} the linear alkyl group of R ² and R ⁷ may have a substituent, and the substituent includes an aryl group, a heteroaryl group, a halogeno group, and a hydroxyl group. , Carboxy group, cyano group, nitro group, sulfo group and the like. It is preferable that the branched alkyl groups of R ¹ and R ^{6 and} the linear alkyl groups of R ² and R ⁷ do not have a substituent.

^{Examples of the organic group of R 3} , R ⁴ , R ⁸ and R ⁹ of the formula (1) include an alkyl group, an alkoxy group, an alkylthio group, an alkoxycarbonyl group, an alkylsulfonyl group, an alkylsulfinyl group, an aryl group and an aralkyl group. , Aryloxy group, arylthio group, aryloxycarbonyl group, arylsulfonyl group, arylsulfinyl group, heteroaryl group, amino group, amide group, sulfonamide group, carboxy group (carboxylic acid group), cyano group and the like. ^{Examples of the polar functional groups of R 3} , R ⁴ , R ⁸ and R ⁹ of the formula (1) include a halogeno group, a hydroxyl group, a nitro group, a sulfo group (sulfonic acid group) and the like.

The alkyl groups of R ³ , R ⁴ , R ⁸ and R ⁹ include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group and heptyl group. , Octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecil group, icosyl group and other linear or branched alkyl groups. Examples thereof include cyclic (aliphatic) alkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group and cyclodecyl group. The alkyl group may have a substituent, and the substituent of the alkyl group includes an aryl group, a heteroaryl group, a halogeno group, a hydroxyl group, a carboxy group, an alkoxy group, a cyano group, a nitro group, an amino group and a sulfo group. The group etc. can be mentioned. Examples of the alkyl group having a halogeno group include a monohalogenoalkyl group, a dihalogenoalkyl group, an alkyl group having a trihalomethyl unit, a perhalogenoalkyl group and the like. As the halogeno group, a fluorine atom, a chlorine atom and a bromine atom are preferable, and a fluorine atom is particularly preferable. The number of carbon atoms of the alkyl group (the number of carbon atoms excluding the substituent) is preferably 1 to 20, and specifically, if it is a linear or branched alkyl group, the number of carbon atoms is preferably 1 to 20 and more preferably 1 to 20. It is 10, more preferably 1 to 5, and if it is a cyclic alkyl group, the number of carbon atoms is preferably 4 to 10, and more preferably 5 to 8.

For specific examples of the alkyl group contained in the alkoxy group, alkylthio group, alkoxycarbonyl group, alkylsulfonyl group and alkylsulfinyl group of ^{R 3} , R ⁴ , R ⁸ and R ^{9, the above description on the alkyl group is referred to.}

Examples ^{of the aryl group of R 3} , R ⁴ , R ⁸ and R ⁹ include a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group, an indenyl group and the like. The aryl group may have a substituent, and examples of the substituent contained in the aryl group include an alkyl group, an alkoxy group, a heteroaryl group, a halogeno group, a halogenoalkyl group, a hydroxyl group, a cyano group, a nitro group and an amino group. Examples thereof include a thiocyanate group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, a sulfo group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group and a sulfamoyl group. The number of carbon atoms of the aryl group (the number of carbon atoms excluding the substituent) is preferably 6 to 20, and more preferably 6 to 12.

Examples of the aralkyl group of R ³ , R ⁴ , R ⁸ and R ⁹ include a benzyl group, a phenethyl group, a phenylpropyl group, a phenylbutyl group, a phenylpentyl group, a naphthylmethyl group and the like. The aralkyl group may have a substituent, and the substituents contained in the aralkyl group include an alkyl group, an alkoxy group, a halogeno group, a halogenoalkyl group, a cyano group, a nitro group, a thiocyanate group, an acyl group and an alkoxycarbonyl group. , Aryloxycarbonyl group, carbamoyl group, sulfo group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group and the like. The carbon number of the aralkyl group (the number of carbon atoms excluding the substituent) is preferably 7 to 25, more preferably 7 to 15.

For specific examples of the aryl group contained in the aryloxy group, arylthio group, aryloxycarbonyl group, arylsulfonyl group, and arylsulfinyl group of ^{R 3} , R ⁴ , R ⁸ and R ^{9, the above description regarding the aryl group is referred to.} NS.

Examples of the heteroaryl groups of R ³ , R ⁴ , R ⁸ and R ⁹ include thienyl group, thiopyranyl group, isothiochromenyl group, pyrrolyl group, imidazolyl group, pyrazolyl group, pyridyl group, pyraridinyl group, pyrimidinyl group and pyridadinyl group. Examples thereof include a group, a thiazolyl group, an isothiazolyl group, a furanyl group, a pyranyl group and the like. The heteroaryl group may have a substituent, and the substituents contained in the heteroaryl group include an alkyl group, an alkoxy group, an aryl group, a halogeno group, a halogenoalkyl group, a hydroxyl group, a cyano group, an amino group and a nitro group. , Thiosianate group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, sulfo group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group and the like. The number of carbon atoms of the heteroaryl group (the number of carbon atoms excluding the substituent) is preferably 2 to 20, more preferably 3 to 15.

The amino groups of R ³ , R ⁴ , R ⁸ and R ⁹ are represented by the ^{formula: -NR a1} R ^{a2 , and R a1} and R a ² are independently hydrogen atoms, alkyl groups, alkenyl groups and alkynyl groups, respectively. , Aryl group, alkyl group, heteroaryl group and the like. Specific examples of an alkyl group, an aryl group, an aralkyl group, and a heteroaryl group refer to the above description of these groups, and the alkenyl group and the alkynyl group are one of the carbon-carbon single bonds of the alkyl group exemplified above. Examples include groups in which the moiety has been replaced with a double or triple bond. R ^a1 and R ^a2 may be connected to each other to form a ring.

The amide group of R ³ , R ⁴ , R ⁸ and R ⁹ is represented by the formula: -NH-C (= O) -R ^{a3 , and R a3} is an alkyl group, an aryl group, an aralkyl group or a heteroaryl group. Some are mentioned. Specific examples of alkyl groups, aryl groups, aralkyl groups, and heteroaryl groups are referred to in the description of these groups above.

The sulfonamide groups of R ³ , R ⁴ , R ⁸ and R ⁹ are represented by the formula: -NH-SO _2- R ^{a4 , and R a4} is an alkyl group, an aryl group, an aralkyl group, or a heteroaryl group. And so on. Specific examples of alkyl groups, aryl groups, aralkyl groups, and heteroaryl groups are referred to in the description of these groups above.

Examples of the halogeno group of R ³ , R ⁴ , R ⁸ and R ⁹ include a fluoro group, a chloro group, a bromo group, an iodine group and the like.

^{R 3} , R ⁴ , R ⁸ and R ⁹ of the formula (1) are preferably hydrogen atoms, alkyl groups, alkoxy groups, aryl groups, aralkyl groups, amide groups or hydroxyl groups, respectively. Such a squarylium compound is relatively easy to manufacture, and the maximum absorption wavelength of the squarylium compound can be controlled in a desired wavelength range by appropriately selecting ^{R 3} , R ⁴ , R ⁸ and R ^9. It becomes. Among them, from the viewpoint of stability and ease of production of the squarylium compound, ^{it is preferable that R 3} , R ⁴ , R ⁸ and R ⁹ are independently hydrogen atoms or alkyl groups, respectively. The alkyl group in this case is preferably linear or branched, and has preferably 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms.

Ring A and ring B of the formula (1) each independently represent a nitrogen-containing heterocycle having 5 or more members. The nitrogen-containing heterocycle of rings A and B is a heterocycle in which a nitrogen atom is bonded to a carbon atom at the para position of the squalylium skeleton of a benzene ring in which ring A or ring B is fused. If the ring A and the ring B are formed from such a nitrogen-containing heterocycle, the maximum absorption peak of the squarylium compound is shifted to the long wavelength side (for example, 685 nm or more) to increase the light transmittance in the red region. , It becomes easy to bring the color of the transmitted light closer to the actual one. In addition, in the nitrogen-containing heterocycle of the ring A and the ring B, the nitrogen atom bonded to the carbon atom at the para position of the squalylium skeleton of the benzene ring in which the ring A or the ring B is condensed is replaced with the nitrogen atom described above. The group R ¹ or R ⁶ is bonded, and the nitrogen-containing heterocycle may have a substituent other than ^{R 1} and R ^6. Rings A and B are preferably non-aromatic nitrogen-containing heterocycles.

The nitrogen-containing heterocycles of rings A and B may have only one nitrogen atom or two or more heteroatoms as heteroatoms constituting the ring. When it has two or more heteroatoms, it must have at least one nitrogen atom, and at least one atom selected from N (nitrogen atom), S (sulfur atom) and O (oxygen atom). Have one or more. Examples of the nitrogen-containing heterocycle of rings A and B include a pyrrolidine ring, a piperidine ring, a hexamethyleneimine ring, a heptamethyleneimine ring, a morpholine ring, a thiomorpholine ring, a piperazine ring and the like. From the viewpoint of ease of production of the squarylium compound, it is preferable that the nitrogen-containing heterocycles of rings A and B have only one nitrogen atom as a hetero atom. That is, except for the nitrogen atom bonded to the carbon atom at the para position of the bond position of the squarylium skeleton of the benzene ring in which the ring A or the ring B is fused, the ring A and the ring B are ring-formed by connecting the carbon atoms. Is preferable. Further, it is preferable that the ring A and the ring B are formed by a single bond in which a carbon atom and a nitrogen atom or carbon atoms are bonded to each other to form a ring, except for a carbon-carbon bond fused to a benzene ring.

The nitrogen-containing heterocycle of rings A and B may have a substituent other than ^{R 1} and R ^6. That is, the nitrogen-containing heterocycles of rings A and B are substituents on ring-constituting atoms other than the nitrogen atom bonded to the carbon atom at the para position of the squarylium skeleton of the benzene ring on which ring A or ring B is fused. May be attached, and examples of such a substituent include the organic group and the polar functional group described above. ^{Among them, as the substituent other than R 1} and R ⁶ which the rings A and B may have, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, a halogeno group, a halogenoalkyl group and a hydroxyl group are preferable. Alkyl groups, aryl groups, aralkyl groups and halogenoalkyl groups are more preferable. In this case, the alkyl group, the alkoxy group, and the halogenoalkyl group preferably have 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms, still more preferably 1 to 3 carbon atoms, and the aryl group has 6 to 12 carbon atoms. Preferably, 6 to 10 is more preferable, and the number of carbon atoms of the alkoxyl group is preferably 7 to 13, and more preferably 7 to 11. The alkyl group may be linear or branched. Ring A and ring B do not have to have a substituent other than ^{R 1} and R ^6.

The number of ring members of rings A and B is 5 or more, preferably 6 or more, preferably 12 or less, more preferably 10 or less, and even more preferably 8 or less. In particular, when the number of ring members of rings A and B is 6 or more, the absorption peak having maximum absorption in the red to near infrared region can be sharpened, and the inclined portion on the short wavelength side of the absorption peak can be sharpened. The tilt can be absorbed. Therefore, the boundary between the transmission wavelength region and the absorption wavelength region is formed sharply, and it is possible to selectively cut the light in the wavelength region corresponding to the absorption peak.

With respect to the constitution of the ring A and the ring B described above, the squarylium compound represented by the following formula (2) is shown as a particularly preferable squarylium compound.

In the formula (2), R ^{1 to} R ⁴ and R ^{6 to} R ⁹ are as described above. R ⁵ represents a hydrogen atom or a substituent bonded to a carbon atom constituting the ring A, R ¹⁰ represents a hydrogen atom or a substituent bonded to a carbon atom constituting the ring B, and m and n are 1 or more. (Preferably an integer of 1 to 7, a more preferably an integer of 1 to 5, and even more preferably an integer of 1 to 3). The plurality of R ^5s may be the same or different from each other, and the plurality of R ^10s may be the same or different from each other. Examples of the substituents of R ⁵ and R ¹⁰ include the organic group and the polar functional group described above. The squarylium compound of formula (2) is a 6-membered or more heterocycle in which ring A and ring B have only one nitrogen atom as a heteroatom, except for a carbon-carbon bond fused with a benzene ring. A carbon atom and a nitrogen atom or carbon atoms are bonded to each other by a single bond to form a ring.

R ⁵ and R ¹⁰ are preferably groups or atoms independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, an aralkyl group, a halogeno group, a halogenoalkyl group, and a hydroxyl group. , A group or atom selected from the group consisting of a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, and a halogenoalkyl group, and a group selected from the group consisting of a hydrogen atom, an alkyl group, and a halogenoalkyl group. Alternatively, it is more preferably an atom. In this case, the alkyl group and the halogenoalkyl group preferably have 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms, and even more preferably 1 to 3 carbon atoms.

A particularly preferable example of the squarylium compound represented by the formula (2) is a compound represented by the following formula (3). In the following formula (3), the above description is referred to for ^{R 1 to} R ⁴ and R ^{6 to} R ^9. That is, ring A and ring B are 6-membered nitrogen-containing heterocycles having only one nitrogen atom as a heteroatom constituting the ring, and the nitrogen-containing heterocycle has substituents other than ^{R 1} and R ^6. It is preferable not to (preferably, among the atoms constituting the ring, no substituent is bonded to the carbon atom which does not condensate with the benzene ring).

The squarylium compound of the present invention preferably has a maximum absorption peak in the wavelength range of 650 nm to 950 nm in the absorption spectrum of the wavelength range of 450 nm to 1100 nm measured in toluene. That is, the squarylium compound has a peak having an absorption maximum in the wavelength range of 650 nm to 950 nm when the absorption spectrum is measured in toluene, and the absorption maximum of the absorption peak has a maximum value in the wavelength range of 450 nm to 1100 nm. Is preferable. The absorption maximum wavelength of the maximum absorption peak is referred to as the maximum absorption wavelength λmax. If the squarylium compound exhibits such an absorption spectrum, it can effectively absorb light in the red to near infrared region. The maximum wavelength λmax is more preferably 670 nm or more, further preferably 685 nm or more, further preferably 900 nm or less, further preferably 850 nm or less, and even more preferably 800 nm or less.

The squarylium compound of the present invention has an absorption spectrum in the wavelength range of 450 nm to 1100 nm measured in toluene, when the absorbance of the maximum absorption peak at the maximum wavelength λmax is 1, the absorbance on the shorter wavelength side than the maximum wavelength λmax. It is preferable that the inclination S _{0.5 at 0.5} is 3.00 × 10 ⁻² nm ^{-1 or more.} When the absorption spectrum of such a squarylium compound is measured, the inclination of the inclined portion on the short wavelength side of the maximum absorption peak becomes steep, so that the boundary between the transmission wavelength region and the absorption wavelength region is sharply formed. be able to. Therefore, it is possible to selectively cut the light in the wavelength range corresponding to the maximum absorption peak. For example, while selectively cutting the light in the near infrared region, the light in the visible light region on the shorter wavelength side. Can be transmitted with high transmittance including red light, and the color of the transmitted light can be brought closer to the actual one. The slope S _0.5 at an absorbance of 0.5 is more preferably 3.15 × 10 ⁻² nm ^-1 or more, further preferably 3.25 × 10 ⁻² nm ^-1 or more, and 3.35 × 10 ⁻² nm ^-1. The above is even more preferable. The upper limit of the slope S _0.5 is not particularly limited, but may be, for example, 5.00 × 10 ⁻² nm ^-1 or less, 4.00 × 10 ⁻² nm ^-1 or less, or 3.75 ×. It ^{may be 10-2} nm ^-1 or less.

The absorption spectrum is obtained by measuring the absorbance at every measurement pitch of 1 nm in the wavelength range of 450 nm to 1100 nm. The value of the absorbance at the wavelength below the measurement pitch (1 nm) is calculated by linear interpolation from the measured value of the absorbance at the measurement pitch of 1 nm. The concentration of the squarylium compound in toluene is adjusted so that the maximum value of absorbance (maximum value of absorbance at the maximum absorption peak) is 1 ± 0.003 in the wavelength range of 450 nm to 1100 nm. In the present invention, when the absorption spectrum is measured under such conditions, it is considered that the absorbance of the maximum absorption peak at the absorption wavelength λmax becomes 1.

_{The gradient S 0.5 at} the absorbance 0.5 on the shorter wavelength side than the maximum wavelength λmax _{is λ 0.55 for} the wavelength at which the absorbance is 0.55 on the shorter wavelength side than λmax, _{and λ 0.45} for the wavelength at which the absorbance is 0.45. Then, it is calculated by the formula: S _0.5 = (0.55-0.45) / (λ _0.55 − λ _0.45 ). Wavelength lambda _0.55 absorbance becomes 0.55, the wavelength lambda _0.45 absorbance becomes 0.45, determined by linear interpolation from the measured absorbance of 1nm pitch. Note that λ _0.55 means the wavelength closest to λmax, which has an absorbance of 0.55 on the shorter wavelength side than λmax, and λ _0.45 is the closest to λmax, which has an absorbance of 0.45 on the shorter wavelength side than λmax. It means a close wavelength.

As for the maximum absorption peak, it is preferable that the shoulder peak is not observed as much as possible on the shorter wavelength side than the absorption maximum λmax. Specifically, it is preferable that the absorption spectrum does not have an absorption maximum in which the absorbance increases by 0.05 or more in the range from the maximum wavelength λmax of the maximum absorption peak to 100 nm on the short wavelength side. That is, in the absorption spectrum measured at a pitch of 1 nm, there is no absorption maximum in the wavelength range from λmax-100 (nm) to λmax (nm), or even if there is an absorption maximum, the longer wavelength side and the shorter wavelength side. It is preferable that the increase in absorbance is less than 0.05. As a result, the boundary between the transmission wavelength region and the absorption wavelength region can be formed sharply. The increase in absorbance at the shoulder peak is more preferably less than 0.03, more preferably less than 0.01, and particularly preferably the absence of an absorption maximum at the shoulder peak.

The squarylium compound of the present invention preferably has an average absorbance in the wavelength range of 450 nm to 600 nm of 0.03 or less, more preferably 0.02 or less, when the absorbance of the maximum absorption peak at the maximum wavelength λmax is 1. , 0.01 or less, which can increase the light transmittance in the visible light region. The average absorbance in the wavelength range of 450 nm to 600 nm is determined by averaging the absorbance values of 151 points measured at a pitch of 1 nm in the wavelength range of 450 nm to 600 nm.

Since the squarylium compound of the present invention is excellent in solubility in an organic solvent, it is preferable to satisfy the following properties. That is, the absorption spectrum of a solution obtained by diluting a filtrate containing 1 part by mass of a squarylium compound and 99 parts by mass of toluene with a filter having a pore size of 0.45 μm with toluene 2500 times has a wavelength in the range of 450 nm to 1100 nm. The maximum absorbance is preferably 1.0 or more. If the squarylium compound is highly soluble in organic solvents, when the squarylium compound is added to toluene, more portion of the squarylium compound will dissolve and the amount of undissolved residue will decrease, so this is filtered with a filter. Then, the squarylium compound will be transferred to the filtrate side in a state of being dissolved in toluene. Therefore, if the absorption spectrum of this filtrate is measured, the absorption peak derived from the squarylium compound will appear more strongly. The details of each operation of filtering, diluting, and measuring the absorbance of the toluene solution of the squarylium compound shall be based on the examples.

The squarylium compound of the present invention can be produced by reacting a compound of the following formula (4-1) with a compound of the following formula (4-2) with squaric acid. In the following formulas (4-1) and (4-2), R ^{1 to} R ⁴ , R ^{6 to} R ⁹ , rings A and ring B have the same meanings as in the above formula (1) and are suitable thereof. Aspects are also as described above. The compound of formula (4-1) and the compound of formula (4-2) may be the same.

The reaction between squaric acid and the above compound is preferably carried out in the presence of a solvent. Examples of the solvent that can be used include chlorine-based hydrocarbons such as chloroform and methylene chloride; aromatic hydrocarbons such as benzene, toluene, xylene and trimethylbenzene; chlorine-based aromatics such as chlorotoluene and dichlorobenzene; tetrahydrofuran. Examples include ethers such as (THF), dioxane, cyclopentylmethyl ether, diisopropyl ether and diethyl ether; alcohols such as methanol, ethanol, propanol and butanol; and the like. Only one of these solvents may be used, or two or more of these solvents may be used in combination.

In the reaction with squaric acid, the reaction temperature may be appropriately set, for example, 30 ° C. or higher is preferable, 60 ° C. or higher is more preferable, 80 ° C. or higher is further preferable, 170 ° C. or lower is preferable, and 140 ° C. or lower is more preferable. .. The reaction is preferably carried out under reflux. The reaction time is not particularly limited and may be appropriately set according to the progress of the reaction. For example, 0.5 hours or more is preferable, 1 hour or more is more preferable, 48 hours or less is preferable, and 24 hours or less is preferable. More preferred. The atmosphere during the reaction is preferably an inert gas (nitrogen, argon, etc.) atmosphere.

The production of squarylium compounds can also be referred to in the following papers: Serguei Miltsov et al., “New Cyanine Dyes: Norindosquarocyanines”, Tetrahedron Letters, Vol.40, Issue 21, p.4067-4068 (1999).

The obtained squarylium compound can be appropriately purified by known purification means such as filtration, silica gel column chromatography, alumina column chromatography, sublimation, recrystallization, and crystallization, if necessary. The chemical structure of the squarylium compound can be analyzed by known analytical methods such as mass spectrometry, single crystal X-ray structure analysis, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy.

The squarylium compound of the present invention can be mixed with a resin component to form a resin composition. The resin composition of the present invention can be suitably applied to an optical filter by forming a resin molded product such as a film. Resin moldings also include near-infrared absorbing films and plates that block heat rays for energy savings, materials for solar cells that utilize visible and near-infrared light, and specific wavelengths for plasma display panels (PDPs) and CCDs. It can also be applied to absorption filters and the like.

The resin composition contains at least the squarylium compound of the present invention and a resin component. The squarylium compound contained in the resin composition may be only one kind or two or more kinds.

Although the squarylium compound of the present invention can be regarded as a kind of dye, the resin composition of the present invention contains other dyes together with the squarylium compound of the present invention as long as the desired performance according to the application is ensured. You may. Examples of the dye that may be contained in the resin composition include a squarylium-based dye other than the squarylium compound of the present invention, a croconium-based dye, and copper (for example, Cu (II)) or zinc (for example, Zn) as the central metal ion. (II))) Cyclic tetrapyrrole dyes (porphyrins, chlorins, phthalocyanines, choliners, etc.), cyanine dyes, quaterylene dyes, naphthalocyanine dyes, nickel complex dyes, etc. Examples thereof include copper ion dyes, diimmonium dyes, subphthalocyanine dyes, xanthene dyes, azo dyes, dipyrromethene dyes and the like. As these other dyes, only one kind may be used, or two or more kinds may be used. Among them, it is preferable to use the squarylium compound of the present invention in combination with the squarylium compound disclosed in Japanese Patent Application Laid-Open No. 2016-0744649 (the squarylium compound represented by the following formula (5)), thereby in the near infrared region. It becomes easy to form a resin composition having a wide absorption wavelength range and exhibiting a high transmittance in a wide range of the visible light region on the shorter wavelength side.

In the above formula (5), R ¹¹ and R ¹² each independently represent a group represented by the following formula (6), and in the following formula (6), the ring P is a 4- to 9-membered unsaturated hydrocarbon. Represents a hydrogen ring, where ring Q represents an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle which may have a substituent, or a fused ring containing these ring structures. R ¹³ represents a hydrogen atom, an organic group or a polar functional group, R ¹⁴ represents an organic group or a polar functional group, and * represents a bonding site with a 4-membered ring (squarylium skeleton) in the formula (5). , K is an integer from 0 to 6 and is less than or equal to h (where h is the number of members of the ring P minus 3), and when k is 2 or more, the plurality of R ^14s are the same. It may be different.

For details of the organic groups and polar functional groups of R ¹³ and R ¹⁴ , refer to the description of the organic groups and polar functional groups of ^{R 3} , R ⁴ , R ⁸ and R ^9. As R ¹³ , a hydrogen atom, an alkyl group, an alkoxycarbonyl group and an aryl group are preferable, and an alkyl group or an aryl group is more preferable. In this case, the number of carbon atoms of the alkyl group is preferably 1 to 6 if it is a linear or branched alkyl group, more preferably 1 to 4, and 4 if it is a cyclic (alicyclic) alkyl group. ~ 7 is preferable, and 5 to 6 is more preferable. The aryl group preferably has 6 to 10 carbon atoms, more preferably 6 to 8 carbon atoms. When R ¹³ is an alkyl group or an aryl group, a methyl group, an ethyl group, an isopropyl group, an isobutyl group, a t-butyl group, a cyclopentyl group, a cyclohexyl group, a phenyl group and the like are preferably mentioned. As R ¹⁴ , an alkyl group, an alkoxy group, a halogeno group, an aryl group, an alkoxycarbonyl group (ester group), an amide group, a sulfonamide group and a hydroxyl group are preferable, an alkyl group or a hydroxyl group is more preferable, and the alkyl group is more preferable. A linear or branched alkyl group having 1 to 4 carbon atoms is preferably used. It is also preferable that the ring P ^{does not have the substituent R 14} , that is, k is 0.

The structure of the ring P includes, for example, cyclobutene, cyclopentene, cyclopentadiene, cyclohexene, cyclohexadiene, cycloheptene, cycloheptadiene, cycloheptatriene, cyclooctene, cyclooctadiene, cyclooctatriene, cyclononene, cyclononadiene, cyclononatriene, and the like. Cycloalkene structures such as cyclononatetraene can be mentioned. Among them, cycloalkanemonoene such as cyclopentene, cyclohexene, cycloheptene, and cyclooctene is preferable, and cyclohexene, cyclohexene, or cyclooctene is more preferable.

Examples of the aromatic hydrocarbon ring of ring Q include a benzene ring, a naphthalene ring, a phenanthrene ring, an anthracene ring, a fluoranthene ring, a cyclotetradecaheptaene ring and the like. The aromatic hydrocarbon ring may have only one ring structure or may be a condensation of two or more ring structures. The aromatic heterocycle of ring Q contains one or more atoms selected from N (nitrogen atom), O (oxygen atom) and S (sulfur atom) in the ring structure and has aromaticity, for example. , Fran ring, thiophene ring, pyrol ring, pyrazole ring, oxazole ring, thiazole ring, imidazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, purine ring, pteridine ring and the like. The aromatic heterocycle may have only one ring structure or may be a condensed product of two or more ring structures. The fused ring containing these ring structures of ring Q has a structure in which an aromatic hydrocarbon ring and an aromatic heterocycle are fused, and for example, an indole ring, an isoindole ring, a benzimidazole ring, and a quinoline ring. , Benzimidazole ring, acridine ring, xanthene ring, carbazole ring and the like.

Ring Q may have a substituent, and examples of the substituent include the organic group and the polar functional group described above. Among them, an alkyl group (preferably a linear or branched alkyl group having 1 to 4 carbon atoms), an aryl group, an alkoxy group (preferably an alkoxy group having 1 to 4 carbon atoms), and an alkylthio group (preferably 1 to 4 carbon atoms). -2 Alkylthio groups), heteroaryl groups, amino groups, amide groups, sulfonamide groups, hydroxyl groups, thiol groups, benzothiazole groups, indolinyl groups and other electron donating groups; halogeno groups (preferably fluoro groups, chloro groups) , Bromo group), halogenoalkyl group (preferably perhalogenoalkyl group having 1 to 3 carbon atoms), cyano group, alkoxycarbonyl group (ester group), carboxy group (carboxylic acid group), carboxylic acid ester group, carboxylic acid amide. An electron-withdrawing group such as a group, a sulfo group (sulfonic acid group), or a nitro group is preferably used. Among these, an electron-withdrawing group is more preferable, and a halogeno group is particularly preferable. The ring Q does not have to have a substituent. When the ring Q has a substituent, the number thereof is preferably 1 to 3, more preferably 1 to 2, and even more preferably 1.

Specific examples of the squarylium compound represented by the formula (5) include squarylium compounds 01 to 30 described in Examples of JP-A-2016-074649. As the squarylium compound represented by the formula (5), a compound in which the ring P is a cyclohexene ring or a cyclooctene ring is preferable, a cyclooctene ring is more preferable, and the ring Q may have a substituent. A benzene ring or a naphthalene ring which may have a substituent is preferable. For details of the squarylium compound represented by the formula (5), refer to the description in JP-A-2016-0744649.

When the squarylium compound of the present invention is used in combination with the squarylium compound of the above formula (5), the content of the squarylium compound of the present invention is 100 mass in total of the squarylium compound of the present invention and the squarylium compound of the above formula (5). With respect to%, 20% by mass or more is preferable, 30% by mass or more is more preferable, 80% by mass or less is preferable, and 70% by mass or less is more preferable.

When the resin composition also contains the squarylium compound of the present invention and a dye other than the squarylium compound of the above formula (5), the content of the other dye is the squarylium compound of the present invention and the above formula (5). 100 parts by mass or less is preferable, 60 parts by mass or less is more preferable, and 30 parts by mass or less is further preferable with respect to 100 parts by mass in total with the squarylium compound.

The content of the squarylium compound in the resin composition (the total content of two or more squarylium compounds when used) is 0 in 100% by mass of the solid content of the resin composition from the viewpoint of exhibiting desired performance. It is preferably 0.01% by mass or more, more preferably 0.3% by mass or more, and further preferably 1% by mass or more. Further, from the viewpoint of improving the moldability and film forming property of the resin composition, the content of the squarylium compound in the resin composition is preferably 25% by mass or less, preferably 20% by mass, based on 100% by mass of the solid content of the resin composition. % Or less is more preferable, and 15% by mass or less is further preferable. When the resin composition also contains a dye other than the squarylium compound of the present invention, the total content thereof is preferably in the above range.

A known resin can be used as the resin component contained in the resin composition. As the resin component, one having high transparency and capable of dissolving the squarylium compound of the present invention is preferable. When other dyes are used in combination, the resin component is preferably one that can dissolve other dyes as well. By selecting such a resin component, it is possible to achieve both high transmittance in the wavelength range to be transmitted and high absorption in the wavelength range to be blocked.

The resin component includes not only a completely polymerized resin but also a resin raw material (including a resin precursor, a raw material of the precursor, a monomer constituting the resin, etc.), and when molding a resin composition. It is also possible to use a resin which is incorporated into a resin by a polymerization reaction or a cross-linking reaction. In the present invention, any resin is included in the resin component. In the latter case, a part of the structure of the squarylium compound is caused by the unreacted substance, the reactive terminal functional group, the ionic group, the catalyst, the acid / basic group, etc., which are present in the reaction solution obtained by the polymerization reaction. Or it is possible that everything will be disassembled. Therefore, when there is such a concern, it is desirable to add a squarylium compound to the polymerized resin to form a resin composition.

As the resin component, it is preferable to use a highly transparent resin, whereby the light selective absorption characteristics of the squarylium compound contained in the resin composition can be suitably utilized. The resin component may be, for example, a thermoplastic resin or a thermosetting resin. Examples of the resin component include (meth) acrylic resin, (meth) acrylic urethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyolefin resin (for example, polyethylene resin and polypropylene resin), cycloolefin resin, and the like. Melamine resin, urethane resin, styrene resin, polyvinyl acetate, polyamide resin (eg nylon), aramid resin, polyimide resin, polyamideimide resin, alkyd resin, phenol resin, epoxy resin, polyester resin (eg polybutylene terephthalate (eg, polybutylene terephthalate) PBT) resin, polyethylene terephthalate (PET) resin, polyarylate resin, etc.), polysulfone resin, butyral resin, polycarbonate resin, polyether resin, ABS resin (acrylonitrile butadiene styrene resin), AS resin (acrylonitrile-styrene copolymer) , Silicone resin, modified silicone resin (eg, (meth) acrylic silicone resin, alkylpolysiloxane resin, silicone urethane resin, silicone polyester resin, silicone acrylic resin, etc.), fluororesin (eg, fluorinated aromatic polymer, etc.) Polytetrafluoroethylene (PTFE), perfluoroalkoxyfluororesin (PFA), fluorinated polyaryl ether ketone (FPEK), fluorinated polyimide (FPI), fluorinated polyamic acid (FPAA), fluorinated polyether nitrile (FPEN) Etc.) etc. Among these, from the viewpoint of excellent transparency and heat resistance, polyimide resin, polyamideimide resin, (meth) acrylic resin, cycloolefin resin, epoxy resin, polyester resin, polyarylate resin, polyamide resin, polycarbonate resin, polysulfone. Resins and fluorinated aromatic polymers are preferable.

The polyimide resin is a polymer containing an imide bond in the repeating unit of the main chain. For example, polycarboxylic acid dianhydride and diamine are polycondensed to obtain polyamic acid, which is dehydrated and cyclized (imidized). ) Can be manufactured. As the polyimide resin, it is preferable to use an aromatic polyimide in which aromatic rings are linked by an imide bond. Polyimide resins include, for example, Neoprim (registered trademark) manufactured by Mitsubishi Gas Chemical Company, Kapton (registered trademark) manufactured by DuPont, Aurum (registered trademark) manufactured by Mitsui Chemical Company, Meldin (registered trademark) manufactured by Coralvan, and Toray. TPS (registered trademark) TI3000 series manufactured by Plastic Seiko Co., Ltd. can be used.

The polyamide-imide resin is a polymer containing an amide bond and an imide bond in the repeating unit of the main chain. As the polyamide-imide resin, for example, Toron (registered trademark) manufactured by Solvay Advanced Polymers, Viromax (registered trademark) manufactured by Toyobo, TPS (registered trademark) TI5000 series manufactured by Toray Plastics Precision Precision Co., Ltd., and the like can be used.

The (meth) acrylic resin is a polymer having a repeating unit derived from (meth) acrylic acid or a derivative thereof, and for example, a repeating unit derived from (meth) acrylic acid ester such as a poly (meth) acrylic acid ester resin. The resin to have is preferably used. The (meth) acrylic resin preferably has a ring structure in the main chain, for example, a carbonyl group-containing ring structure such as a lactone ring structure, a glutaric anhydride structure, a glutalimido structure, a maleic anhydride structure, and a maleimide ring structure; oxetane. Examples thereof include a carbonyl group-free ring structure such as a ring structure, an azetidine ring structure, a tetrahydrofuran ring structure, a pyrrolidine ring structure, a tetrahydropyran ring structure, and a piperidine ring structure. The carbonyl group-containing ring structure also includes a structure containing a carbonyl group derivative group such as an imide group. Examples of the (meth) acrylic resin having a carbonyl group-containing ring structure are described in JP-A-2004-168882, JP-A-2008-179677, International Publication No. 2005/54311, JP-A-2007-31537 and the like. The described ones can be used.

The cycloolefin-based resin is a polymer obtained by using cycloolefin as at least a part of the monomer component and polymerizing the cycloolefin, and is not particularly limited as long as it has an alicyclic structure in a part of the main chain. Examples of cycloolefin resins include Topas (registered trademark) manufactured by Polyplastics, Appel (registered trademark) manufactured by Mitsui Chemicals, Zeonex (registered trademark) and Zeonoa (registered trademark) manufactured by Zeon Corporation, and JSR Corporation. Arton (registered trademark) manufactured by Zeon Corporation can be used.

Epoxy resin is a resin that can be cured by cross-linking an epoxy compound (prepolymer) in the presence of a curing agent or a curing catalyst. Examples of the epoxy compound include aromatic epoxy compounds, aliphatic epoxy compounds, alicyclic epoxy compounds, hydrogenated epoxy compounds and the like. For example, fluorene epoxy manufactured by Osaka Gas Chemical Co., Ltd. (Ogsol (registered trademark) PG-100). , Mitsubishi Chemical's bisphenol A type epoxy compound (JER (registered trademark) 828EL), hydrogenated bisphenol A type epoxy compound (JER (registered trademark) YX8000), and Daicel's alicyclic liquid epoxy compound (celloxide (registered)) Trademark) 2021P) and the like can be used.

The polyester resin is a polymer containing an ester bond in the repeating unit of the main chain, and can be obtained, for example, by polycondensing a polyvalent carboxylic acid (dicarboxylic acid) and a polyalcohol (diol). Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate and the like. For example, OKP series manufactured by Osaka Gas Chemical Co., Ltd., TRN series manufactured by Teijin Co., Ltd., Theonex ( Registered trademark), Dupont's Lynite (registered trademark), Mitsubishi Chemical's Novapex (registered trademark), Mitsubishi Engineering Plastics' Novaduran (registered trademark), Toray's Lumirer (registered trademark), Trecon (registered trademark) Registered trademark), Elitel (registered trademark) manufactured by Unitica, etc. can be used.

The polyarylate resin is a polymer obtained by polycondensing a divalent phenol compound and a dibasic acid (for example, an aromatic dicarboxylic acid such as phthalic acid), and has an aromatic ring and an ester bond in the repeating unit of the main chain. It has a repeating unit including and. As the polyarylate resin, for example, Vectran (registered trademark) manufactured by Kuraray, U polymer (registered trademark) manufactured by Unitika Ltd., Unifiedr (registered trademark), and the like can be used.

The polyamide resin is a polymer containing an amide bond in the repeating unit of the main chain, and can be obtained, for example, by polycondensing diamine and a dicarboxylic acid. The polyamide resin may have an aliphatic skeleton in the main chain, and as such an amide resin, for example, nylon can be used. The polyamide resin may have an aromatic skeleton, and an aramid resin is known as such a polyamide resin. Aramid resin is preferably used because it has excellent heat resistance and strong mechanical strength. For example, Teijin's Twaron (registered trademark), Cornex (registered trademark), DuPont's Kevlar (registered trademark), and Nomex. (Registered trademark) and the like can be used.

The polycarbonate resin is a polymer containing a carbonate group (-O- (C = O) -O-) as a repeating unit of the main chain. Polycarbonate resins include Teijin Panlite (registered trademark), Mitsubishi Engineering Plastics Iupilon (registered trademark), Novarex (registered trademark), Zanter (registered trademark), and Sumika Stylon Polycarbonate SD Polycarbonate. (Registered trademark) and the like can be used.

The polysulfone resin is a polymer having a repeating unit containing an aromatic ring, a sulfonyl group (−SO _{2−), and an oxygen atom.} As the polysulfone resin, for example, Sumika Excel (registered trademark) PES3600P or PES4100P manufactured by Sumitomo Chemical Co., Ltd., UDEL (registered trademark) P-1700 manufactured by Solvay Specialty Polymers, etc. can be used.

The fluorinated aromatic polymer is a repeat containing an aromatic ring having one or more fluorine atoms and at least one bond selected from the group consisting of an ether bond, a ketone bond, a sulfone bond, an amide bond, an imide bond and an ester bond. It is a polymer having a unit, and among these, a polymer essentially containing a repeating unit containing an aromatic ring having one or more fluorine atoms and an ether bond is preferable. As the fluorinated aromatic polymer, for example, those described in JP-A-2008-181121 can be used.

The resin component preferably has high transparency, which facilitates suitable application of the resin composition to optical applications. For the resin component, for example, the total light transmittance at a thickness of 0.1 mm is preferably 75% or more, more preferably 80% or more, still more preferably 85% or more. The upper limit of the total light transmittance of the resin component is not particularly limited, and the total light transmittance may be 100% or less, but may be, for example, 95% or less. Total light transmittance is measured based on JIS K 7105.

The resin component preferably has a high glass transition temperature (Tg), which can enhance the heat resistance of the resin composition and various molded articles obtained from the resin composition. The glass transition temperature of the resin component is, for example, preferably 110 ° C. or higher, more preferably 120 ° C. or higher, and even more preferably 130 ° C. or higher. The upper limit of the glass transition temperature of the resin component is not particularly limited, but is preferably 380 ° C. or lower, for example, from the viewpoint of ensuring the molding processability of the resin composition.

The resin composition may contain a solvent or may be a paint. The coated resin composition facilitates coating of the resin composition by containing a solvent. The paint-based resin composition can be obtained, for example, by dissolving the squarylium compound in a solvent containing a resin component, or by dispersing the squarylium compound in a solvent (dispersion medium) containing a resin component. The solvent may function as a solvent (solvent) for the squarylium compound, or may function as a dispersion medium. Examples of the solvent include ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; glycol derivatives such as PGMEA (2-acetoxy-1-methoxypropane), ethylene glycol monobutyl ether, ethylene glycol monoethyl ether and ethylene glycol ethyl ether acetate. Classes (ether compounds, ester compounds, ether ester compounds, etc.); amides such as N, N-dimethylacetamide; esters such as ethyl acetate, propyl acetate, butyl acetate; N-methyl-pyrrolidone (specifically, 1). Pyrrolidones such as −methyl-2-pyrrolidone); aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as cyclohexane and heptane; ethers such as tetrahydrofuran, dioxane, diethyl ether and dibutyl ether; etc. Can be mentioned. Only one of these solvents may be used, or two or more of these solvents may be used in combination.

The content of the solvent is preferably, for example, 50% by mass or more, more preferably 70% by mass or more, preferably less than 100% by mass, and more preferably 95% by mass or less in 100% by mass of the resin composition. By adjusting the content of the solvent within such a range, it becomes easy to obtain a resin composition having a high concentration of the squarylium compound.

Since amides such as N and N-dimethylacetamide may decompose the squarylium compound, it is preferable that the amount used is small. Therefore, the content of amides is preferably 60% by mass or less, more preferably 40% by mass or less, further preferably 20% by mass or less, still more preferably 5% by mass or less, and 0% by mass in 100% by mass of the resin composition. % Is particularly preferred (ie, does not contain amides).

The resin composition may contain, for example, a compound (ultraviolet absorber) having an absorbent ability in the wavelength range of 350 nm to 400 nm. Due to the presence of these compounds, deterioration of the resin composition due to light in the wavelength range of 350 nm to 400 nm can be suppressed. When a compound having an absorbing ability in the wavelength range of 350 nm to 400 nm is used in combination, examples of the compound having an absorbing ability in the wavelength range of 350 nm to 400 nm include TINUVIN (registered trademark) series manufactured by BASF and Sankyo Kasei Co., Ltd. Dislyzer (registered trademark) series, Adecastab (registered trademark) series manufactured by Adeca, Sumisorb (registered trademark) series manufactured by Sumitomo Chemical Co., Ltd., Biosorb (registered trademark) series manufactured by Kyodo Yakuhin Co., Ltd. Trademark) series and the like can be used.

The resin composition may contain a surface conditioner, which suppresses appearance defects such as striations and dents in the resin layer when the resin composition is cured to form a resin layer. can do. The type of the surface conditioner is not particularly limited, and a siloxane-based surfactant, an acetylene glycol-based surfactant, a fluorine-based surfactant, an acrylic-based leveling agent, and the like can be used. As the surface conditioner, for example, BYK (registered trademark) series manufactured by Big Chemie Co., Ltd., KF series manufactured by Shin-Etsu Chemical Co., Ltd., and the like can be used.

The resin composition may contain a dispersant, whereby even if a part of the squarylium compound in the resin composition is present in a dispersed state, the dispersibility is stabilized and the reaggregation of the squarylium compound is suppressed. can do. The type of dispersant is not particularly limited, and is EFKA series manufactured by Fuka Additives, BYK (registered trademark) series manufactured by Big Chemie, Solsperse (registered trademark) series manufactured by Japan Lubrizol, and Disparon manufactured by Kusumoto Kasei Co., Ltd. (Registered Trademark) Series, Ajinomoto Fine Techno Co., Ltd. Ajispar (Registered Trademark) Series, Shinetsu Chemical Industry Co., Ltd. KP Series, Kyoeisha Chemical Co., Ltd. Polyflow Series, DIC Co., Ltd. MegaFuck (Registered Trademark) Series, A Disper Aid series manufactured by San Nopco Ltd. can be used.

The resin composition may contain a silane coupling agent, a hydrolyzate thereof, or a hydrolyzed condensate thereof, and when the resin composition is cured on the substrate to form a resin layer, the substrate of the resin layer is formed. Adhesion to the plastic can be improved.

The resin composition may contain various additives such as a plasticizer, a surfactant, a viscosity modifier, an antifoaming agent, a preservative, and a resistivity adjuster, if necessary.

The resin composition can be made into a cured product by curing. The resin composition may be cured by heating (softening) and cooling, or may be cured by a reaction of resin components (for example, a polymerization reaction or a cross-linking reaction). The contained solvent may be removed and cured. Examples of the resin composition include a thermoplastic resin composition that can be molded by injection molding, extrusion molding, or the like, a spin coating method, a solvent casting method, a roll coating method, a spray coating method, a bar coating method, and a dip coating method. , A resin composition that has been made into a paint so that it can be coated by a screen printing method, a flexo printing method, an inkjet method, or the like can be used.

When the resin composition is a thermoplastic resin composition, a cured product can be obtained by subjecting the resin composition to injection molding, extrusion molding, vacuum molding, compression molding, blow molding, or the like. In this method, a molded product can be obtained by blending a squarylium compound with a thermoplastic resin and heat-molding. For example, it is preferable to add a squarylium compound to the powder or pellet of the base resin, heat it to about 150 ° C. to 350 ° C. to dissolve it, and then mold it. The shape of the molded product is not particularly limited, but plate-like, sheet-like, granular, powder-like, lump-like, particle-aggregate-like, spherical, elliptical-spherical, lenticular-like, cubic-like, columnar, rod-like, and conical-like. Examples include a tubular shape, a needle shape, a fibrous shape, a hollow thread shape, and a porous shape. Further, when kneading the resin, an additive used for ordinary resin molding such as a plasticizer may be added.

When the resin composition is a paint-based resin composition, a liquid or paste-like resin composition containing a squarylium compound is applied onto a substrate (for example, a resin plate, a film, a glass plate, etc.). It is possible to obtain a cured product in the form of a film having a thickness of 200 μm or less or in the form of a sheet having a thickness of more than 200 μm. The cured product thus obtained can be peeled off from the base material and handled as a film or sheet, or can be handled integrally with the base material.

The cured product of the resin composition may be composed of a single resin layer (a layer formed by curing the resin composition), or may be composed of a plurality of resin layers. When the cured product is handled integrally with the base material, the cured product may be formed on only one side of the base material or on both sides. The cured product and the base material integrated can also be formed by thermocompression bonding or chemically bonding the molded product formed from the resin composition to the base material.

The resin composition of the present invention can be preferably used as a resin composition for forming a filter used in various applications such as opt device applications, display device applications, mechanical parts, and electrical / electronic parts. The resin composition and its cured product can be suitably applied to, for example, an optical filter such as a near-infrared cut filter. Such a filter may be formed from a single or a plurality of resin layers, or may be formed integrally with a support.

The filter integrated with the support is, for example, when the resin composition has another layer such as a binder layer between the support surface (or the support and the resin layer, the surface of the other layer). ) Can be formed by applying it to) by a spin coating method or a solvent casting method, and drying or curing it. Further, the filter may be formed by thermocompression bonding a planar molded body formed of the resin composition to the support.

The resin layer formed from the resin composition may be provided on only one side of the support, or may be provided on both sides. The thickness of the resin layer is not particularly limited, but from the viewpoint of ensuring the desired near-infrared ray cutting performance, for example, 0.5 μm or more is preferable, 1 μm or more is more preferable, 2 μm or more is further preferable, and 1 mm or less is preferable, and 500 μm. The following is more preferable, and 200 μm or less is further preferable. When the resin layer is formed by applying a paint-based resin composition on the support, the strength of the filter can be ensured by the support, so that the thickness of the resin layer should be further reduced. Can be done. When the resin layer is formed on the support, the thickness of the resin layer is, for example, preferably 50 μm or less, more preferably 20 μm or less, further preferably 10 μm or less, and particularly preferably 5 μm or less.

As the support, it is preferable to use a transparent substrate such as a resin plate, a resin film, or a glass plate. As the resin plate or resin film used for the support, for example, one formed from the resin components described above is preferably used. From the viewpoint of increasing the heat resistance of the optical filter, it is preferable to use a glass substrate as the support, and the optical filter formed in this way can be mounted on an electronic component by, for example, solder reflow. Further, since the glass substrate is less likely to crack or warp even when exposed to a high temperature, it becomes easy to secure the adhesion with the resin layer. When a glass substrate is used as the support, a binder layer formed of, for example, a silane coupling agent may be provided between the support and the resin layer, thereby improving the adhesion between the resin layer and the glass substrate. Can be done. Even if the resin composition forming the resin layer contains a silane coupling agent as an adhesion improver, the adhesion between the resin layer and the glass substrate can be improved.

The thickness of the support (board) is preferably 0.05 mm or more, more preferably 0.1 mm or more, and preferably 0.4 mm or less, preferably 0.3 mm, from the viewpoint of ensuring strength. The following is more preferable.

A protective layer made of the same or different resin as the resin layer may be laminated on the resin layer formed from the resin composition as a second resin layer. By providing the protective layer, the durability (decomposition resistance) of the squarylium compound contained in the resin layer can be enhanced. The protective layer may be provided on only one side of the resin layer, or may be provided on both sides. When the resin layer is provided on the support, it is preferable that the protective layer is provided on the surface of the resin layer opposite to the support.

When forming an optical filter from the resin composition of the present invention, the optical filter is a layer having antireflection and antiglare properties (antireflection film) that reduces reflection of fluorescent lamps and the like, and a layer having scratch prevention performance. , A transparent base material having other functions, etc. may be provided.

The optical filter may have a near-infrared reflective film (for example, a reflective film in the wavelength range of 700 nm to 800 nm) on the resin layer. The near-infrared reflective film is preferably provided on the light receiving side of the resin layer. If the optical filter is provided with a near-infrared reflective film, the near-infrared rays can be further cut from the transmitted light of the optical filter. The near-infrared reflective film may also have an ultraviolet reflecting function.

The near-infrared reflective film and the antireflection film (visible light antireflection film) can be composed of a dielectric multilayer film in which high refractive index material layers and low refractive index material layers are alternately laminated. Therefore, when imparting such a function to the optical filter, it is preferable that the optical filter has a dielectric multilayer film. As a material constituting the high refractive index material layer, a material having a refractive index of 1.7 or more can be used, and a material having a refractive index in the range of 1.7 to 2.5 is usually selected. Examples of the material constituting the high refractive index material layer include oxides such as titanium oxide, zinc oxide, zirconium oxide, lanthanum oxide, yttrium oxide, indium oxide, niobium oxide, tantalum oxide, tin oxide, and bismuth oxide; silicon nitride. The oxides and mixtures of the nitrides, and those obtained by doping them with metals such as aluminum and copper or carbon (for example, tin-doped indium oxide (ITO), antimonated tin oxide (ATO)) and the like can be mentioned. Be done. As the material constituting the low refractive index material layer, a material having a refractive index of 1.6 or less can be used, and a material having a refractive index in the range of 1.2 to 1.6 is usually selected. Examples of the material constituting the low refractive index material layer include silicon dioxide (silica), alumina, lanthanum fluoride, magnesium fluoride, sodium hexafluoride, and the like.

The optical filter may also have an aluminum vapor deposition film, a noble metal thin film, a resin film in which metal oxide fine particles containing indium oxide as a main component and a small amount of tin oxide are dispersed.

The thickness of the optical filter is preferably 1 mm or less, for example. Thereby, for example, it is possible to sufficiently meet the demand for miniaturization of the image sensor. The thickness of the optical filter is more preferably 500 μm or less, still more preferably 300 μm or less, even more preferably 150 μm or less, preferably 30 μm or more, still more preferably 50 μm or more.

The optical filter can be used as one of the constituent members of a sensor such as an image sensor (imaging element), an illuminance sensor, and a proximity sensor. For example, an image sensor is used as an electronic component that converts the light of a subject into an electric signal or the like and outputs it, and examples thereof include a CCD (Charge Coupled Device) and a CMOS (Complementary Metal-Oxide Semiconductor). The image sensor can be used for a mobile phone camera, a digital camera, an in-vehicle camera, a surveillance camera, a display element (LED or the like), or the like. The sensor includes one or more of the above optical filters, and may have other filters (for example, a visible light cut filter, an infrared cut filter, an ultraviolet cut filter, etc.) and a lens, if necessary.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples, and is carried out with appropriate modifications to the extent that it can be adapted to the gist of the above and the following. It is also possible, and all of them are included in the technical scope of the present invention.

(1) Synthesis of compound (1-1) Synthesis example 1: Synthesis of squarylium compound A 5 g of dimethylformamide, 2.2 g of potassium carbonate, 1.07 g of 1,2,3,4-tetrahydroquinoline in a 300 mL 4-neck flask. (0.008 mol), 1.4 g of 2-iodopropane was added, and the mixture was reacted under 80 ° C. conditions for 4 hours while stirring with a stirring blade under nitrogen flow (10 mL / min). After completion of the reaction, the obtained reaction solution was added to a beaker containing 50 mL of an aqueous potassium hydroxide solution and 50 mL of ethyl acetate with stirring. The aqueous solution was alkaline. After stirring for a while, the organic phase was extracted with a separating funnel, and magnesium sulfate (anhydrous) was added to the extracted organic phase for dehydration. After the solid matter (inorganic component) was filtered off from this organic phase, the solvent was distilled off using an evaporator. After distillation, silica gel column chromatography (developing solvent: chloroform) was appropriately used, and the mixture was concentrated and vacuum dried to obtain 0.9 g of Intermediate A1. The yield based on 1,2,3,4-tetrahydroquinoline was 64.2 mol%.

Next, 2.80 g (0.0160 mol) of intermediate A1 and 46 g of sulfuric acid were placed in a 50 mL two-necked flask under nitrogen flow (10 mL / min), and the temperature inside the flask was 0 while stirring using a stirring blade. It was ice-cooled to ~ 5 ° C. 8.2 g of a mixed acid composed of 1.6 g of nitric acid and 6.6 g of sulfuric acid was gently added dropwise thereto so that the temperature in the flask could be maintained at 0 to 5 ° C., and stirring was continued for 1 hour after the completion of the addition. After completion of stirring, the obtained reaction solution was put into 200 g of ice water, and 60 g of potassium hydroxide was added little by little to neutralize. After the addition of potassium hydroxide, the aqueous solution was alkaline. After adding 200 g of ethyl acetate and stirring for a while, the organic phase was extracted with a separating funnel, and magnesium sulfate (anhydrous) was added to the extracted organic phase for dehydration. After the solid matter (inorganic component) was filtered off from this organic phase, the solvent was distilled off using an evaporator. After distillation, silica gel column chromatography (developing solvent: chloroform) was appropriately used, and the mixture was concentrated and vacuum dried to obtain 3.1 g of Intermediate A2. The yield with respect to Intermediate A1 was 88.0 mol%.

Next, 2.64 g (0.012 mol) of intermediate A2 and 9.0 g of concentrated hydrochloric acid (hydrochloric acid concentration 36% by weight) were placed in a 100 mL two-necked flask, and a magnetic stirrer was placed under nitrogen flow (5 mL / min). A solution containing 9.1 g of tin chloride dihydrate and 9.1 g of concentrated hydrochloric acid (hydrochloric acid concentration 36% by weight) was added little by little while paying attention to the heat of reaction. After the addition, the mixture was stirred at room temperature for about 3 hours. Then, the obtained reaction solution was added to a beaker containing 100 g of pure water and 100 g of ethyl acetate with stirring. Potassium hydroxide solution is added little by little, and after stirring for a while when the pH of the aqueous solution becomes around 10, the organic phase is extracted with a liquid separation funnel, and magnesium sulfate (anhydrous) is added to the extracted organic phase. And dehydrated. After the solid matter (inorganic component) is filtered off from this organic phase, the solvent is concentrated using an evaporator, and then silica gel column chromatography (developing solvent: chloroform) is appropriately used, and the mixture is concentrated and vacuum dried. 0.96 g of body A3 was obtained. The yield with respect to Intermediate A2 was 42.0 mol%.

Next, 2.72 g (0.0143 mol) of intermediate A3 and 50 g of super-dehydrated chloroform were placed in a 100 mL three-necked flask, and triethylamine was added under nitrogen flow (5 mL / min) while stirring with a magnetic stirrer. 4.34 g (0.0429 mol) and 5.45 g (0.0286 mol) of n-decanoyl chloride were added, and the mixture was reacted at room temperature for 12 hours. After completion of the reaction, the obtained reaction solution was added to ion-exchanged water and extracted with ethyl acetate. Magnesium sulfate (anhydrous) was added to the extracted organic phase for dehydration. After the solid matter (inorganic component) is filtered off from this organic phase, the solvent is concentrated using an evaporator, and then silica gel column chromatography (developing solvent: chloroform) is appropriately used, and the mixture is concentrated and vacuum dried. 3.10 g of body A4 was obtained. The yield with respect to Intermediate A3 was 62.9 mol%.

Next, 4.93 g (0.0143 mol) of intermediate A4, 0.82 g (0.0072 mmol) of squaric acid, 30 g of 1-butanol, and 30 g of toluene were placed in a 300 mL two-necked flask, and the mixture was placed under nitrogen flow (10 mL / min). ), Stirrer using a magnetic stirrer, and reacting under reflux conditions for 3 hours while removing the eluted water using a Dean-Stark apparatus. After completion of the reaction, the mixture was cooled to room temperature and the precipitate was filtered off. The filtered precipitate was washed with methanol, and only the precipitate was filtered again, and the obtained cake (solid) was purified by column chromatography with alumina (developing solvent: chloroform). The obtained purified product was dried at 60 ° C. for 12 hours using a vacuum dryer to obtain 3.9 g of the target squarylium compound A. The yield with respect to squaric acid was 71.1 mol%.

(1-2) Synthesis Example 2: Synthesis of Squalylium Compound B Follow the same procedure as in Synthesis Example 1 except that n-decanoyl chloride was changed to palmitoyl chloride (n-hexadecanoyl chloride) in Synthesis Example 1. The squarylium compound B shown in Table 1 was obtained. The yield with respect to squaric acid was 86.1 mol%.

(1-3) Synthesis Example 3: Synthesis of Squalylium Compound C 110 g of chloroform, 1.8 g of acetic acid, and 5.4 g (0.0303 mol) of 7-nitro-1,2,3,4-tetrahydroquinoline in a 300 mL 4-neck flask. ), 12.84 g (0.0606 mol) of sodium triacetoxyborohydride was added, and 4.37 g (0.0606 mol) of isobutyraldehyde was added over 10 minutes while stirring with a stirring blade under nitrogen flow (10 mL / min). Dropped. After completion of the dropping, the obtained reaction solution was added to 300 g of water and neutralized with hydrochloric acid. 300 g of ethyl acetate was added thereto, the organic phase was extracted with a separating funnel, and magnesium sulfate (anhydrous) was added to the extracted organic phase for dehydration. After the solid matter (inorganic component) is filtered off from this organic phase, the solvent is concentrated using an evaporator, and then silica gel column chromatography (developing solvent: chloroform) is appropriately used, and the mixture is concentrated and vacuum dried. 6.13 g of body C1 was obtained. The yield on 7-nitro-1,2,3,4-tetrahydroquinoline was 86.4 mol%. Then, from the intermediate C1, the intermediate C2 was synthesized according to the procedure for synthesizing the intermediate A2 to the intermediate A3 of Synthesis Example 1 (however, the intermediate A2 is changed to the intermediate C1). The yield of Intermediate C2 with respect to Intermediate C1 was 83.0 mol%. Further, from the intermediate C2, the intermediate C3 was synthesized according to the procedure for synthesizing the intermediate A3 to the intermediate A4 of Synthesis Example 1 (however, the intermediate A3 is changed to the intermediate C2). The yield of Intermediate C3 with respect to Intermediate C2 was 92.0 mol%. Then, from the intermediate C3, the squalylium compound C was synthesized according to the procedure for synthesizing the squalylium compound A from the intermediate A4 of Synthesis Example 1 (however, the intermediate A4 was changed to the intermediate C3). The yield of squalylium compound C with respect to squaric acid was 63.5 mol%.

(1-4) Synthesis Example 4: Synthesis of Squalylium Compound D The squalylium compound D shown in Table 1 was prepared by the same procedure as in Synthesis Example 3 except that n-decanoyl chloride was changed to palmitoyl chloride in Synthesis Example 3. Obtained. The yield with respect to squaric acid was 77.4 mol%.

(1-5) Synthesis Example 5: Synthesis of Comparative Squalylium Compound A Comparative Squalylium Compound A shown in Table 1 was prepared by the same procedure as in Synthesis Example 2 except that 2-iodopropane was changed to iodomethane in Synthesis Example 2. Obtained. The yield with respect to squaric acid was 51.8 mol%.

(1-6) Synthesis Example 6: Synthesis of Comparative Squalylium Compound B Comparative Squalylium Compound B shown in Table 1 was obtained by the same procedure as in Synthesis Example 4 except that isobutyraldehyde was changed to propionaldehyde in Synthesis Example 4. rice field. The yield with respect to squaric acid was 69.9 mol%.

(1-7) Synthesis Example 7: Synthesis of Comparative Squalylium Compound C Table 1 follows the same procedure as in Synthesis Example 6 except that palmitoyl chloride was changed to valeryl chloride (n-pentanoyl chloride) in Synthesis Example 6. The comparative squarylium compound C shown in the above was obtained. The yield with respect to squaric acid was 77.3 mol%.

(1-8) Synthesis Example 8: Synthesis of Comparative Squalylium Compound D The comparative squalylium compound D shown in Table 1 was prepared by the same procedure as in Synthesis Example 4 except that palmitoyl chloride was changed to valeryl chloride in Synthesis Example 4. Obtained. The yield with respect to squaric acid was 48.2 mol%.

(1-9) Synthesis Example 9: Synthesis of Comparative Squalylium Compound E The comparative squalylium compound E shown in Table 1 was synthesized with reference to the squalylium compound disclosed in Formula 17 of US Pat. No. 5,543,086. ..

(2) Preparation of resin composition (2-1) Preparation of curing catalyst Ando Parachemy Co., Ltd. with a TPB (tris (pentafluorophenyl) borane) content of 7% according to the synthesis method described in International Publication No. 1997/031924. (Registered Trademark) Isopar (registered trademark) E solution (255 g) was prepared. Water was added dropwise to this solution at 60 ° C. to precipitate white crystals, which were cooled to room temperature, suction filtered, and washed with n-heptane. The obtained cake was dried under reduced pressure at 60 ° C. to obtain 18.7 g of a TPB / water complex (TPB-containing powder) as white crystals. This complex had a water content of 9.2% (Karl Fischer titer) and a TPB content of 90.8%. ¹⁹ F-NMR analysis and GC analysis were performed on the dried complex, but no peaks other than TPB were detected. 2.0 g of the obtained TPB / water complex and 1.1 g of toluene were mixed and mixed at room temperature for 10 minutes. Then, 2.6 g of a 2 mol / L ammonia / ethanol solution was added and mixed at room temperature for 60 minutes to prepare a uniform solution of the TPB catalyst. This was used as a cationic curing catalyst.

(2-2) Preparation of silane hydrolyzate solution 3-glycidoxypropyltrimethoxysilane (manufactured by Toray Dow Corning, ofs-6040) 24.7 parts by mass, 2-propanol 32.1 parts by mass and distilled water 3.4 parts by mass was mixed and mixed uniformly at 25 ° C. To this, 1.54 parts by mass of formic acid was added and mixed for 90 minutes to proceed with the hydrolysis reaction of 3-glycidoxypropyltrimethoxysilane to obtain a silane hydrolyzate solution.

(2-3) Preparation of Resin Composition 1 As an epoxy resin, 1,2-epoxy-4- (2-oxylanyl) cyclohexane adduct of 2,2-bis (hydroxymethyl) -1-butanol (manufactured by Daicel Co., Ltd., EHPE3150) ) Is 100 parts by mass, 150 parts by mass of toluene and 75 parts by mass of o-xylene as a solvent, 8.9 parts by mass of the squarylium compound B obtained in Synthesis Example 2 above, and BYK-306 manufactured by Big Chemie as a surface conditioner. (Polyether-modified polydimethylsiloxane) was blended in an amount of 0.3 parts by mass and mixed uniformly at 40 ° C. After the temperature of the obtained mixture is lowered to 25 ° C., 2.5 parts by mass of the cation curing catalyst obtained above and 10 parts by mass of the silane hydrolyzate solution are added and mixed uniformly, and this is mixed with a filter having a pore size of 0.45 μm. A resin composition 1 was obtained by filtering with a chromatographic disk non-aqueous 13N) manufactured by GL Sciences Co., Ltd. to remove foreign substances.

(2-4) Preparation of Resin Composition 2 In the above preparation example of the resin composition 1, the same procedure was followed except that the comparative squarylium compound B obtained in Synthesis Example 6 was used instead of the squarylium compound B. Epoxy resin composition 2 was obtained.

(3) Preparation of Optical Filter After 2 cc of each of the resin compositions obtained above was dropped on a glass substrate (D263Teco manufactured by Schott), a spin coater (1HD7 manufactured by Mikasa) was used. The resin composition was formed on a glass substrate at 1600 rotations over 2 seconds, held at that rotation speed for 20 seconds, and then at 0 rotations over 0.2 seconds. The glass substrate on which the resin composition was formed was initially dried at 100 ° C. for 3 minutes using a precision incubator (manufactured by Yamato Scientific Co., Ltd., DH611). Then, nitrogen was replaced at 50 ° C. for 30 minutes using an inert oven (manufactured by Yamato Scientific Co., Ltd., DN610I), the temperature was raised to 190 ° C. in about 15 minutes, and the mixture was dried at 190 ° C. for 30 minutes in a nitrogen atmosphere. A resin layer (absorption layer) was formed on the glass substrate. The thickness of the resin layer formed on the glass substrate was 2 μm. The thickness of the resin layer was determined by measuring the thickness of the glass substrate on which the resin layer was formed and the thickness of the glass substrate alone with a micrometer, and determining the difference between the two.

(4) Evaluation (4-1) Solubility 9.9 g of toluene was added to 0.1 g of each of the squarylium compounds shown in Table 1, and the mixture was heated and stirred at 40 ° C. for 1 hour, and then stirred at room temperature for 1 hour to obtain the results. The solution was filtered through a polytetrafluoroethylene (PTFE) syringe filter (GL Sciences, Inc., chromatodisk 13N) having a pore size of 0.45 μm. The filtrate was weighed into a 50 mL volumetric flask with a 1 mL volumetric pipette, scalpel-up with toluene, and mixed well. The obtained diluted solution was further weighed into a 50 mL volumetric flask with a 1 mL volumetric pipette, scalpel-up with toluene, and mixed well. The absorption spectrum of the solution (2500-fold diluted solution) thus obtained was measured at a measurement pitch of 1 nm using a spectrophotometer (manufactured by Shimadzu Corporation, UV-1800), and the maximum in the wavelength range of 300 nm to 1100 nm. The absorbance was determined and summarized in Table 2. The maximum absorption wavelength of each squarylium compound in toluene was about 700 nm, and no absorption peak was substantially shown in the wavelength range of 450 nm to 600 nm in the visible light region.

(4-2) Transmission spectrum of optical filter For each optical filter having a resin layer formed on a glass substrate, the transmission spectrum was measured at a measurement pitch of 1 nm using a spectrophotometer (UV-1800, manufactured by Shimadzu Corporation). The transmittance of light at a wavelength of 300 nm to 1100 nm was determined. The transmission spectrum of the optical filter formed from the resin composition 1 containing the squarylium compound B is shown in FIG. 1, and the transmission spectrum of the optical filter formed from the resin composition 2 containing the comparative squarylium compound B is shown in FIG.

The optical filter formed from the resin composition 2 containing the comparative squarylium compound B showed an absorption peak having an absorption maximum near a wavelength of 700 nm and an absorption peak having an absorption maximum near a wavelength of 560 nm. The comparative squarylium compound B did not exhibit the original spectral characteristics of the comparative squarylium compound B as shown in the solution in the cured resin product. On the other hand, the optical filter formed from the resin composition 1 containing the squarylium compound B shows an absorption peak having an absorption maximum near a wavelength of 700 nm, and substantially shows an absorption peak in the wavelength range of 450 nm to 600 nm in the visible light region. There wasn't. Comparative Squalylium compounds other than Squalylium compound B exhibited the original spectral characteristics of the squarylium compound as shown in the solution in the cured resin product.

(4-3) Summary In the squarylium compounds A to D, R ¹ and R ⁶ of the above formula (1) are branched alkyl groups having 3 or more carbon atoms, and R ² and R ⁷ are linear chains having 5 or more carbon atoms. Since it was an alkyl group, it had high solubility in toluene, a small amount of undissolved residue, and a high maximum absorbance in a toluene solution. In the cured resin product, light in the red to near infrared region is selectively absorbed while transmitting light in the visible light region with high transmittance according to the original absorption spectrum of the squarylium compound. On the other hand, in the comparative squarylium compounds A, C to E, since R ¹ and R ⁶ of the above formula (1) were linear alkyl groups or R ² and R ⁷ were alkyl groups having 4 or less carbon atoms, they were converted to toluene. The solubility of the compound was low, and the maximum absorbance in the toluene solution was low. Comparative squarylium compound B had high solubility in toluene, but showed a new absorption peak with maximum absorption near the wavelength of 560 nm, which was not seen in the solution in the cured resin, and the visible light transmittance was increased. It became inferior.

The squarylium compound of the present invention can be used, for example, in electronic components such as mobile phone cameras, digital cameras, in-vehicle cameras, surveillance cameras, display elements (LEDs, etc.), security inks, and the like.

Claims (6)

A squarylium compound represented by the following formula ( 3).

[In equation ( 3 ),
Each R ¹ and ^{R 6} independently represent a carbon number 3 to 6 branched alkyl group,
R ² and ^{R 7} each independently represent a carbon number 8 to 18 linear alkyl group,
R ^{3, R} 4, ^{R 8} and ^{R 9} to display the hydrogen atom. ] The absorption spectrum of a solution obtained by diluting a filtrate containing 1 part by mass of a squarylium compound and 99 parts by mass of toluene with a filter having a pore size of 0.45 μm and diluting it 2500 times with toluene has a maximum absorbance in the wavelength range of 450 nm to 1100 nm. The squarylium compound according to claim 1, wherein the content is 1.0 or more. A resin composition comprising the squarylium compound according to claim 1 or 2 and a resin component. A cured product obtained by curing the resin composition according to claim 3. Optical filter which comprises a cured product according to the resin composition or claim 4 according to claim 3. A sensor comprising the optical filter according to claim 5.

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