JP7772129B2 - Optical filter, imaging device and optical sensor - Google Patents

Description

The present invention relates to an optical filter that transmits light in the visible wavelength range and blocks light in the near-infrared wavelength range, as well as an imaging device and optical sensor equipped with the optical filter.

In order to reproduce color tones well and obtain clear images, imaging devices using solid-state imaging elements use optical filters that transmit light in the visible range (hereinafter also referred to as "visible light") and block light in the near-infrared range (hereinafter also referred to as "near-infrared light"). A known example of such an optical filter is a near-infrared cut filter, which has an absorption layer containing a near-infrared absorbing dye and resin on a glass substrate, and a reflective layer made of a dielectric multilayer film that blocks near-infrared light.

Such near-infrared cut filters are used in applications such as ambient light sensors, and in these cases, they are required to absorb light in a specific long wavelength range of near-infrared light and have high transmittance in the visible light range.

For example, Patent Document 1 discloses an optical filter for an ambient light sensor that uses a dye that has absorption capabilities in the long wavelength range of near-infrared light, that is, wavelengths of 850 to 1050 nm.

Patent Document 2 also describes a technology for near-infrared cut filters that, instead of absorbing glass that absorbs in the long wavelength region of near-infrared light, have good absorption characteristics in this wavelength region, can be easily produced in small, thin shapes, are less likely to develop micro-defects during polishing, and are cost-effective and productive. Patent Document 2 discloses a technology for obtaining near-infrared cut filters with the above characteristics using an optical film containing a transparent resin and a dye that combines a diimonium dye, a cyanine dye, and an onium salt.

International Publication No. 2017/094672 Japanese Patent Application Publication No. 2008-303130

However, the above-mentioned optical filters, which use an absorption layer containing a specific dye and transparent resin that has the ability to absorb light in the long wavelength range of near-infrared light, do not have a sufficiently high transmittance for visible light, particularly for green and red light, which have a strong influence on visual perception.

The present invention aims to provide an optical filter that can effectively block light in the long wavelength range of near-infrared light, particularly light in the wavelength range of 850 to 1100 nm, while maintaining sufficiently high transmittance for visible light, particularly green and red light, and to provide an imaging device and optical sensor that use this optical filter and have excellent color reproducibility.

An optical filter according to one aspect of the present invention is an optical filter including a transparent resin, an absorption layer containing a near-infrared absorbing dye (A) having a maximum absorption wavelength in a wavelength region of 850 to 1100 nm, and a dielectric multilayer film,
Satisfy all of the following requirements (3-2) to (3-8).
(3-2) In the optical properties measured at an incident angle of 0 degrees, the average transmittance T _{AVE490-560 (0°)} in the wavelength range of 490 to 560 nm is 82% or more.
(3-3) In the optical properties measured at an incident angle of 0 degrees, the average transmittance T _{AVE590-630 (0°)} in the wavelength range of 590 to 630 nm is 50% or more.
(3-4) In the wavelength region of 600 to 800 nm, the absolute value of the difference between the wavelength λ _{50% (0°)} at which the transmittance is 50% at an incident angle of 0 degrees and the wavelength λ _{50% (30°)} at which the transmittance is 50% at an incident angle of 30 degrees, |λ _{50% (30°)} −λ _{50% (0°)} |, is 5 nm or less.
(3-5) The average transmittance T _{AVE490-560(30°)} in the wavelength region of 490 to 560 nm measured at an incident angle of 30 degrees is 80% or more.
(3-6) The minimum OD value in the wavelength region of the maximum absorption wavelength λ _max(A)TR of the near-infrared absorbing dye (A) ±10 nm, measured at an incident angle of 30 degrees, is 3 or more.
(3-7) In the wavelength region of 600 to 800 nm, the absolute value of the difference between the wavelength λ _50%(0°) at which the transmittance is 50% at an incident angle of 0 degrees and the wavelength λ _50%(50°) at which the transmittance is 50% at an incident angle of 50 degrees, |λ _50%(50°) −λ _50%(0°) |, is 15 nm or less.
(3-8) The average transmittance T _{AVE490-560(50°)} in the wavelength region of 490 to 560 nm measured at an incident angle of 50 degrees is 70% or more.

The present invention also provides an imaging device and an optical sensor equipped with the optical filter of the present invention.

The present invention provides an optical filter that can effectively block light in the long wavelength range of near-infrared light, particularly light in the wavelength range of 850 to 1100 nm, while maintaining sufficiently high transmittance for visible light, particularly green and red light, as well as an imaging device and optical sensor that use this optical filter and have excellent color reproducibility.

FIG. 1 is a cross-sectional view schematically illustrating an example of an optical filter according to an embodiment. FIG. 2 is a cross-sectional view schematically showing another example of the optical filter according to the embodiment. FIG. 3 is a cross-sectional view schematically showing another example of the optical filter according to the embodiment. FIG. 4 is a cross-sectional view schematically showing another example of the optical filter according to the embodiment. FIG. 5 is a cross-sectional view schematically showing another example of the optical filter according to the embodiment. FIG. 6 is a cross-sectional view schematically showing another example of the optical filter according to the embodiment. FIG. 7 is a graph showing the spectral transmittance curves of the dye (A1a-5NS) in Test Example 2 in the transparent resin P and in dichloromethane. FIG. 8 is a graph showing the spectral transmittance curves of the dye (A1a-5NS) in Test Example 19 in a transparent resin other than the transparent resin P and in dichloromethane. FIG. 9 is a diagram showing the spectral transmittance curve of the absorption layer in the optical filter of the example (Example 1; Example). FIG. 10 is a diagram showing the spectral transmittance curve of the optical filter of the embodiment (Example 1; embodiment). FIG. 11 is a diagram showing the spectral transmittance curve of the absorption layer in the optical filter of the example (Example 4; Example). FIG. 12 is a diagram showing the spectral transmittance curve of the optical filter of the example (Example 4; Example). FIG. 13 is a diagram showing the spectral transmittance curve of the absorption layer in the optical filter of the example (Example 6; Example). FIG. 14 is a diagram showing the spectral transmittance curve of the optical filter of the example (Example 6; Example). FIG. 15 is a diagram showing the spectral transmittance curve of the absorption layer in the optical filter of the example (Example 8; Comparative Example). FIG. 16 is a diagram showing the spectral transmittance curve of the optical filter of the example (Example 8; Comparative Example).

Hereinafter, an embodiment of the present invention will be described.
In this specification, the near-infrared absorbing dye may be abbreviated as "NIR dye" and the ultraviolet absorbing dye may be abbreviated as "UV dye".

In this specification, a compound represented by formula (A1) is referred to as compound (A1). The same applies to compounds represented by other formulas. A dye consisting of compound (A1) is also referred to as dye (A1), and the same applies to other dyes. Furthermore, for example, a group represented by formula (1x) is also referred to as group (1x), and the same applies to groups represented by other formulas.

In this specification, internal transmittance is the transmittance obtained by subtracting the effect of interfacial reflection from the measured transmittance, as expressed by the formula: measured transmittance / (100 - reflectance). In this specification, the transmittance of a transparent substrate made of resin, and the transmittance spectrum of a resin layer, including those in which a dye such as an absorption layer is contained in the resin, are all "internal transmittance" even when referred to as "transmittance." On the other hand, the transmittance measured by dissolving a dye in a solvent such as dichloromethane, and the transmittance of an optical filter having a dielectric multilayer film are all measured transmittance.

In this specification, for example, a transmittance of 90% or more in a specific wavelength range means that the transmittance is not below 90% in the entire wavelength range, i.e., the minimum transmittance in that wavelength range is 90% or more. Similarly, for example, a transmittance of 1% or less in a specific wavelength range means that the transmittance is not more than 1% in the entire wavelength range, i.e., the maximum transmittance in that wavelength range is 1% or less. The same applies to internal transmittance. The average transmittance and average internal transmittance in a specific wavelength range are the arithmetic mean of the transmittance and internal transmittance per 1 nm in that wavelength range.
In this specification, the use of "to" to indicate a range of values includes the upper and lower limits.

<Optical filter>
An optical filter according to one embodiment of the present invention (hereinafter also referred to as "the filter") comprises a transparent resin (hereinafter also referred to as "transparent resin (P)") having a glass transition temperature (hereinafter also referred to as "Tg") of 130°C or higher, an absorption layer containing an NIR dye (A) that satisfies all of the requirements (1-1) to (1-6) below, and a reflective layer made of a dielectric multilayer film.

(1-1) In the spectral transmittance curve SC _TR at wavelengths of 350 to 1200 nm measured by incorporating the NIR dye (A) into the transparent resin (P), the maximum absorption wavelength λ _max(A)TR is in the wavelength region of 850 to 1100 nm.
(1-2) In the spectral transmittance curve SC _TR , when the internal transmittance at the maximum absorption wavelength λ _max(A)TR is 10%, the average internal transmittance T _{AVE490-560(A)TR} of light with wavelengths of 490 to 560 nm is 90% or more.

(1-3) In the spectral transmittance curve SC _TR , when the internal transmittance at the maximum absorption wavelength λ _max(A)TR is 10%, the average internal transmittance T _{AVE590-630(A)TR} of light with wavelengths of 590 to 630 nm is 90% or more.
(1-4) The spectral transmittance curve SC _TR has two wavelengths in the wavelength region of 650 to 1150 nm at which the internal transmittance is 50% when the internal transmittance at the maximum absorption wavelength λ _max(A)TR is 10%, and the width between the two wavelengths is 180 nm or more.

(1-5) The NIR dye (A) is dissolved in dichloromethane and measured at a wavelength of 350 to 1200 nm in a spectral transmittance curve SC _DCM . When the transmittance of light at the maximum absorption wavelength λ _{max(A) DCM} is set to 10%, the value obtained by subtracting the average internal transmittance T _{AVE490-560(A) TR from the average transmittance T AVE490-560(A)} DCM for light with a wavelength of 490 to 560 nm is 10% or less.
(1-6) The spectral transmittance curve SC _DCM has a maximum absorption wavelength λ _{max (A) DCM.} When the transmittance of light at this wavelength is 10%, the average transmittance T _{AVE590-630(A) DCM} for light having a wavelength of 590 to 630 nm is subtracted from the average internal transmittance T _{AVE590-630(A) TR} , which is 10% or less.

This filter's absorption layer contains an NIR dye (A) with properties (1-1) to (1-6) and a transparent resin (P), which effectively blocks light in the long wavelength range of near-infrared light, particularly light in the 850 to 1100 nm wavelength range, while maintaining sufficiently high transmittance for visible light, particularly green and red light. It is generally known that NIR dyes with maximum absorption wavelengths in the long wavelength range, due in part to aggregation, make it difficult to reproduce the high transmittance of visible light in dichloromethane in a transparent resin. As shown above in (1-5) to (1-6), the NIR dye (A) maintains high transmittance for visible light in dichloromethane in relation to the transparent resin (P).

The NIR dye (A) preferably satisfies one or more of the following (1-7) to (1-9), more preferably two or more, and particularly preferably all of them.

(1-7) The average internal transmittance T _{AVE435-480(A)TR} of light having a wavelength of 435 to 480 nm when the internal transmittance at the maximum absorption wavelength λ _{max(A)TR in the} spectral transmittance curve _{SC TR} is 10% is less than or equal to 10%.
(1-8) The value obtained by subtracting the average internal transmittance T AVE490-560(A) _{TR from the average transmittance T AVE490-560(A) DCM} is 5% or less.
(1-9) The value obtained by subtracting the average internal transmittance T AVE590-630(A) _{TR from the average transmittance T AVE590-630(A) DCM} is 5% or less.

The filter may further include a transparent substrate. In this case, the absorbing layer and the reflective layer are provided on the main surface of the transparent substrate. The filter may include the absorbing layer and the reflective layer on the same main surface of the transparent substrate, or on different main surfaces. When the absorbing layer and the reflective layer are provided on the same main surface, there are no particular limitations on the order in which they are stacked.

This filter may also have other functional layers. Examples of other functional layers include an anti-reflection layer that suppresses loss of visible light transmittance. In particular, when the absorption layer is configured as the outermost surface, loss of visible light transmittance occurs due to reflection at the interface between the absorption layer and air, so it is recommended to provide an anti-reflection layer on the absorption layer.

Next, an example of the filter configuration will be described using the drawings. FIG. 1 shows an example of an optical filter 10A having a reflective layer 12 on one major surface of an absorbing layer 11. In the optical filter 10A, the absorbing layer 11 can be composed of a layer containing an NIR dye (A) and a transparent resin (P). The absorbing layer 11 may further contain an NIR dye (B) and/or an NIR dye (C), as described below. In this case, the absorbing layer 11 may be composed of multiple laminated layers, each containing an appropriate combination of an NIR dye (A), an NIR dye (B), and/or an NIR dye (C). Note that "having a reflective layer 12 on one major surface (above) of the absorbing layer 11" does not necessarily mean that the reflective layer 12 is provided in contact with the absorbing layer 11, but also includes a case in which another functional layer is provided between the absorbing layer 11 and the reflective layer 12, and the same applies to the following configurations.

Figure 2 is a cross-sectional view schematically illustrating an example of an optical filter according to an embodiment having a transparent substrate, an absorption layer, and a reflection layer. Optical filter 10B has a transparent substrate 13, an absorption layer 11 disposed on one major surface of transparent substrate 13, and a reflection layer 12 disposed on the other major surface of transparent substrate 13. In optical filter 10B, absorption layer 11 can have the same configuration as optical filter 10A.

Figure 3 shows an example of the configuration of optical filter 10C, which includes an absorption layer 11 and reflective layers 12a and 12b on both major surfaces of the absorption layer 11. Figure 4 shows an example of the configuration of optical filter 10D, which includes an absorption layer 11 on one major surface of a transparent substrate 13 and reflective layers 12a and 12b on the other major surface of the transparent substrate 13 and on the major surface of the absorption layer 11. In optical filters 10C and 10D, the absorption layer 11 can have the same configuration as optical filter 10A.

Figure 5 shows an example configuration of an optical filter 10E that includes absorption layers 11a and 11b on both major surfaces of a transparent substrate 13, and further includes reflection layers 12a and 12b on the major surfaces of the absorption layers 11a and 11b.

In Figures 3, 4, and 5, the two combined reflective layers 12a, 12b may be the same or different. For example, reflective layers 12a, 12b may have the properties of reflecting ultraviolet light and near-infrared light and transmitting visible light, with reflective layer 12a reflecting ultraviolet light and light in the first near-infrared range, and reflective layer 12b reflecting ultraviolet light and light in the second near-infrared range.

Also, in Figure 5, at least one of the two absorption layers 11a and 11b has the above-described configuration in this filter. Absorption layers 11a and 11b may be the same or different. When absorption layers 11a and 11b are different, for example, absorption layers 11a and 11b may each be a combination of a near-infrared absorption layer and an ultraviolet absorption layer, or a combination of an ultraviolet absorption layer and a near-infrared absorption layer.

Furthermore, in the optical filter 10E, when the absorption layers 11a and 11b contain NIR dye (B) and/or NIR dye (C) described below in addition to the NIR dye (A), the NIR dyes contained in the absorption layers 11a and 11b can be combined as appropriate. For example, when the optical filter 10E contains NIR dyes (A) to (C), one of the absorption layers 11a and 11b may contain one type selected from the NIR dyes (A) to (C), and the other may contain two types. Furthermore, the absorption layers 11a and 11b may each be a single layer or a laminate of multiple layers.

Figure 6 shows an example of the configuration of an optical filter 10F that has an anti-reflection layer 14 on the main surface of the absorption layer 11 of the optical filter 10B shown in Figure 2. If no reflection layer is provided and the absorption layer is configured as the outermost surface, it is preferable to provide an anti-reflection layer on the absorption layer. The anti-reflection layer may be configured to cover not only the outermost surface of the absorption layer, but also the entire side surface of the absorption layer. In this case, the moisture-proof effect of the absorption layer can be enhanced.

The absorbing layer, the reflective layer, the transparent substrate and the anti-reflection layer will be described below.
(Absorption layer)
The absorbing layer contains an NIR dye (A) having the properties (1-1) to (1-6) above, and preferably further having one or more properties selected from the properties (1-7) to (1-9) above, and a transparent resin (P).

The absorbing layer is typically a layer or (resin) substrate in which the NIR dye (A) is uniformly dissolved or dispersed in the transparent resin (P). The absorbing layer may contain other NIR dyes in addition to the NIR dye (A) as long as the effects of the present invention are not impaired. Furthermore, the absorbing layer may contain dyes other than the NIR dye, particularly UV dyes, as long as the effects of the present invention are not impaired.

Other preferred NIR dyes are NIR dye (B), which has a maximum absorption wavelength in the wavelength range of 1100 to 1200 nm, and NIR dye (C), which is a squarylium dye, which has a maximum absorption wavelength in the wavelength range of 630 to 750 nm, when measured in a spectral transmittance curve for wavelengths of 350 to 1200 nm when incorporated into a transparent resin (P). Depending on the required characteristics of the filter, the absorption layer may contain either NIR dye (B) or NIR dye (C), or both, in addition to NIR dye (A).

By including NIR dye (B) in the absorption layer, it is possible to absorb near-infrared light in a wavelength range longer than the absorption wavelength range of NIR dye (A), and the absorption layer can achieve absorption in a wavelength range equivalent to that of absorbing glass. By including NIR dye (C) in the absorption layer, it is possible to reduce the effect of the incidence angle dependency of the reflective layer, which is made of a dielectric multilayer film, in this filter.

[NIR dye (A)]
As defined in (1-1), the NIR dye (A) has a maximum absorption wavelength λ max _{( A)TR} in the wavelength range of 850 to 1100 nm, and preferably in the wavelength range of 900 to 1050 nm.

As defined in (1-2), the NIR dye (A) has a T _{AVE490-560(A)TR} of 90% or more. The T _{AVE490-560(A)TR} is preferably 92% or more, and more preferably 94% or more. As defined in (1-3), the NIR dye (A) has a T _{AVE590-630(A)TR} of 90% or more. The T _{AVE590-630(A)TR} is preferably 91% or more, and more preferably 94% or more.

As defined in (1-4), the NIR dye (A) has a spectral transmittance curve SC _TR , when the internal transmittance at the maximum absorption wavelength λ _{max (A) TR} is 10%, at two wavelengths in the wavelength region of 650 to 1150 nm at which the internal transmittance is 50%, and the width W _T50% between the two wavelengths is 180 nm or more. W _T50% is preferably 200 nm or more, more preferably 300 nm or more. The wavelength on the shorter wavelength side of the wavelengths at which the internal transmittance is 50% is preferably 650 nm or more, more preferably 700 nm or more. The upper limit of _{W T50%} is preferably about 380 nm, more preferably about 370 nm, and even more preferably about 320 nm.

As defined in (1-5), the NIR dye (A) has a T _{AVE490-560(A)DCM} -T _{AVE490-560(A)TR} of 10% or less, and as defined in (1-6), the T _{AVE590-630(A)DCM} -T _{AVE590-630(A)TR} of 10% or less. Each of _{T AVE490-560(A)DCM} -T _{AVE490-560(A)TR} and T _{AVE590-630(A)DCM} -T _{AVE590-630(A)TR} is preferably 8% or less.

Here, T _{AVE490-560(A)DCM} and T _{AVE590-630(A)DCM} are the average transmittance of light with a wavelength of 490 to 560 nm and the average transmittance of light with a wavelength of 590 to 630 nm, respectively, when the transmittance of light at the maximum absorption wavelength λ _max(A)DCM in the spectral transmittance curve SC _DCM of 350 to 1200 nm measured by dissolving the NIR dye (A) in dichloromethane is 10%. _{λ max(A)DCM} is preferably in the wavelength range of 850 to 1100 nm, more preferably in the wavelength range of 900 to 1000 nm.

The NIR dye (A) preferably has a T _{AVE435-480(A)DCM} -T _{AVE435-480(A)TR} shown in (1-7) of 10% or less, more preferably 9% or less, and even more preferably 7% or less. The NIR dye (A) preferably has a T _{AVE490-560(A)DCM} -T _{AVE490-560(A)TR} shown in (1-8) of 5% or less, more preferably 4% or less, and even more preferably 3% or less. The NIR dye (A) preferably has a T _{AVE590-630(A)DCM} -T _{AVE590-630(A)TR} shown in (1-9) of 5% or less, more preferably 4% or less, and even more preferably 3% or less.

There are no particular restrictions on the molecular structure of the NIR dye (A), so long as it satisfies the requirements (1-1) to (1-6) in relation to the transparent resin (P). Specific examples include at least one dye selected from the group consisting of cyanine dyes, croconium dyes, phthalocyanine dyes, squarylium dyes, diimonium dyes, tris-type immonium dyes, and diketopyrrolopyrrole dyes. Tris-type immonium dyes are particularly preferred from the standpoint of high visible light transmittance and wide absorption layer width.

Specific examples of the tris-type immonium dye that is the NIR dye (A) include one or more compounds selected from the group consisting of compounds represented by the following formula (A1) and compounds represented by the following formula (A2):

The symbols in formulas (A1) and (A2) are as follows:
R ²⁰¹ to R ²⁰⁶ and R ²²¹ to R ²²⁶ are each independently a hydrogen atom, a halogen atom, a sulfo group, a hydroxy group, a cyano group, a nitro group, a carboxyl group, a phosphate group, an optionally substituted alkyl or alkoxy group having 1 to 20 carbon atoms which may have an oxygen atom between the carbon atoms, or an optionally substituted aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, or a heterocyclic group having 3 to 14 members, excluding groups in which a substituted or unsubstituted amino group is bonded to a phenyl group. Furthermore, in R ²⁰¹ to R ²⁰⁶ and R ²²¹ to R ²²⁶ , two groups bonded to the same nitrogen atom may bond to each other to form a 3 to 8-membered heterocyclic ring together with the nitrogen atom, and a hydrogen atom bonded to the ring may be substituted with an alkyl group having 1 to 12 carbon atoms.

R ²⁰⁷ to R ²¹⁸ and R ²²⁷ to R ²³⁸ are each independently a hydrogen atom, a halogen atom, an optionally substituted amino group, an amido group, a cyano group, a nitro group, a carboxyl group, or an alkyl group or alkoxy group having 1 to 12 carbon atoms which may be substituted with a halogen atom. In R ²⁰⁷ to R ²¹⁸ and R ²²⁷ to R ²³⁸ , two adjacent groups may be bonded to each other to form a ring having 3 to 8 members together with two carbon atoms of the phenyl group, and a hydrogen atom bonded to the ring may be substituted with an alkyl group having 1 to 12 carbon atoms.

In R ²⁰¹ to R ²⁰⁶ and R ²²¹ to R ²²⁶ , examples of the substituent in the optionally substituted alkyl or alkoxy group having 1 to 20 carbon atoms, the optionally substituted aryl group having 6 to 14 carbon atoms, the aralkyl group having 7 to 14 carbon atoms, or the heterocyclic group having 3 to 14 members include a halogen atom, a hydroxyl group, an amino group which may be substituted with an alkyl group having 1 to 6 carbon atoms, a carboxyl group, a sulfo group, a cyano group, and an acyloxy group having 1 to 6 carbon atoms.

When no ring is formed, R ²⁰⁷ to R ²¹⁸ and R ²²⁷ to R ²³⁸ are each independently preferably a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 12 carbon atoms. The alkyl or alkoxy group preferably has 1 to 6 carbon atoms, and more preferably has 1 to 4 carbon atoms.

In R ²⁰⁷ to R ²¹⁸ and R ²²⁷ to R ²³⁸ , the ring formed by bonding two adjacent groups together with the two carbon atoms of the phenyl group may be an alicyclic ring, an aromatic ring, or a heterocyclic ring. Examples of heteroatoms include a nitrogen atom, an oxygen atom, and a sulfur atom.

In R ²⁰⁷ to R ²¹⁸ and R ²²⁷ to R ²³⁸ , there are six combinations in total of two pairs of adjacent groups bonded to each other in the three phenyl groups bonded to the central nitrogen atom in formula (A1) and formula (A2). Specifically, in formula (A1), there are six pairs: R ²⁰⁷ and R ²⁰⁸ , R ²⁰⁹ and R ²¹⁰ , R ²¹¹ and R ²¹² , R ²¹³ and R ²¹⁴ , R ²¹⁵ and R ²¹⁶ , and R ²¹⁷ and R ²¹⁸ . In formula (A2), there are six pairs of R ²²⁷ and R ²²⁸ , R ²²⁹ and R ²³⁰ , R ²³¹ and R ²³² , R ²³³ and R ²³⁴ , R ²³⁵ and R ²³⁶ , and R ²³⁷ and R ²³⁸ .

In R ²⁰⁷ to R ²¹⁸ in formula (A1) and R ²²⁷ to R ²³⁸ in formula (A2), the number of pairs of adjacent groups bonded may be one, two or more, or up to six pairs may all be bonded. It is preferred that one pair for each of the three phenyl groups, for a total of three pairs, be bonded.

Specific examples of the divalent group formed by bonding two adjacent groups include alkylene groups having 1 to 6 carbon atoms, which may contain 1 or 2 nitrogen atoms as heteroatoms and which may have an unsaturated bond between atoms. More specific examples include the following groups (X-1) to (X-4). Note that the hydrogen atoms in these divalent groups may be substituted with alkyl groups having 1 to 12 carbon atoms.

—(CH ₂ ) _n —(n is an integer of 1 to 6) (X-1)
-CH=CH-CH=CH-...(X-2)
-CH ₂ -CH=CH-...(X-3)
-N=CH-NH-...(X-4)

R ²⁰⁷ to R ²¹⁸ and R ²²⁷ to R ²³⁸ are each independently preferably a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 12 carbon atoms, more preferably a hydrogen atom, or an alkyl or alkoxy group having 1 to 12 carbon atoms. The alkyl or alkoxy group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms.

Furthermore, R ²⁰¹ and R ²⁰⁷ , R ²⁰² and R ²¹⁰ , R ²⁰³ and R ²¹¹ , R ²⁰⁴ and R ²¹⁴ , R ²⁰⁵ and R ²¹⁵ , R ²⁰⁶ and R ²¹⁸ , R ²²¹ and R ²²⁷ , R ²²² and R ²³⁰ , R ²²³ and R ²³¹ , R ²²⁴ and R ²³⁴ , R ²²⁵ and R ²³⁵ , and R ²²⁶ and R ²³⁸ may be bonded to each other to form a 4-8 membered heterocycle together with the nitrogen atom bonded to the phenyl group and two carbon atoms of the phenyl group, and a hydrogen atom bonded to the ring may be substituted by an alkyl group having 1 to 12 carbon atoms.
Xa ^- and Xb ^- each independently represent a monovalent anion.

In the above, the alkyl group may be linear, branched, or cyclic, or may be a combination of these structures. The same applies to the alkyl group when the aryl group below has an alkyl group, and the alkyl group of the aralkyl group below. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms, with fluorine and chlorine atoms being preferred.

In the above, an aryl group refers to a group that bonds via a carbon atom constituting an aromatic ring (but not including a heteroatom) possessed by an aromatic compound, such as a benzene ring, naphthalene ring, or biphenyl. Aryl groups also include structures in which hydrogen atoms bonded to ring-constituting atoms other than the carbon atom that contributes to the bond are substituted with alkyl groups, such as tolyl and xylyl groups.

In the above, an aralkyl group refers to a group in which an alkyl group is bonded to an aromatic ring (but does not contain heteroatoms) via a carbon atom that constitutes the alkyl group. Aralkyl groups also include structures in which a hydrogen atom bonded to a ring-constituting atom other than the atom to which the alkyl group that contributes to the bond is bonded is substituted with an alkyl group.

In the above, the heterocyclic group is a group in which the atoms constituting the ring are bonded via atoms constituting an alicyclic or aromatic ring composed of carbon atoms and atoms other than carbon atoms. Heterocyclic groups include a structure in which hydrogen atoms bonded to ring-constituting atoms other than the atoms contributing to the bond are substituted with alkyl groups. Atoms other than carbon atoms contained in the heterocyclic ring include oxygen atoms, nitrogen atoms, and sulfur atoms, and the number of atoms other than carbon atoms is preferably 1 to 2.

Xa ^- and Xb ^- each independently include Cl ^- , Br ^- , I ^- , F ^- , ClO ₄ ^- , BF ₄ ^- , PF ₆ ^- , SbF ₆ ^- , CF ₃ SO ₃ ^- , CH ₃ C ₆ H ₄ SO ₃ ^- , N[SO ₂ R _f ] ₂ ^- , C[SO ₂ R _f ] ₃ ^{- ,} and the like.

Here, _Rf is a fluoroalkyl group having 1 to 4 carbon atoms, preferably a fluoroalkyl group having 1 to 2 carbon atoms, and more preferably a fluoroalkyl group having 1 carbon atom. When the number of carbon atoms is within the above range, durability such as heat resistance and moisture resistance, and solubility in organic solvents described below are good. Examples of such _Rf include _{perfluoroalkyl} groups such as _{-CF3 , -C2F5} , _-C3F7 , _{and -C4F9} , _{-C2F4H , -C3F6H , and -C2F8H} .

From the standpoint of moisture resistance, the fluoroalkyl group is preferably a perfluoroalkyl group, and more preferably a trifluoromethyl group.

Xa ^- and Xb ^- are each independently preferably I ^- , BF ^{4 -} , SbF ₆ ^- , PF ₆ ^- , ClO ₄ ^- , N[SO ₂ CF ₃ ] ₂ ^- , C[SO ₂ CF ₃ ] ₃ ^{- ,} etc., with SbF ₆ ^- , PF ₆ ^- and N[SO ₂ CF ₃ ] ₂ ^- being more preferred in terms of small difference in optical properties between a dichloromethane solution and a resin, and SbF ₆ ^- and N[SO ₂ CF ₃ ] ₂ ^- being particularly preferred. Also, from the viewpoint of light durability, BF ^{4 -} , PF ₆ ^- , and N[SO ₂ CF ₃ ] ₂ ^- are preferred.

Dye (A1) was classified into three types of dyes (A1a) to (A1c) represented by the following formulas (A1a), (A1b), and (A1c), respectively, based on the structure of the group bonded to the nitrogen atom bonded to the 4th position of the three phenyl groups bonded to the central nitrogen atom. Dye (A2) was similarly classified into three types of dyes (A2a) to (A2c) represented by the following formulas (A2a), (A2b), and (A2c), respectively, based on the structure of the group bonded to the nitrogen atom bonded to the 4th position of the three phenyl groups bonded to the central nitrogen atom.

Dye (A1a) and dye (A2a) have a structure in which the nitrogen atoms bonded to the 4-positions of the three phenyl groups (hereinafter referred to as the 4-position nitrogen atoms) do not form a heterocycle.

Dye (A1b) and dye (A2b) each have a structure in which at least one pair of two groups bonded to three nitrogen atoms at the 4-position are bonded to each other to form a heterocycle. Two pairs of two groups bonded to three nitrogen atoms at the 4-position may be bonded to each other, or all three pairs may be bonded to each other.

Dye (A1c) and dye (A2c) have a structure in which at least one of the two groups bonded to the three nitrogen atoms at the 4-position is bonded to a group bonded to the 3- or 5-position of the phenyl group to form a heterocycle. Dye (A1c) and dye (A2c) may have 2 to 6 such heterocycles.

In formula (A1a) and formula (A2a), R ²⁰¹ to R ²⁰⁶ and R ²²¹ to R ²²⁶ are each independently a hydrogen atom, a halogen atom, a sulfo group, a hydroxy group, a cyano group, a nitro group, a carboxyl group, a phosphate group, an optionally substituted alkyl or alkoxy group having 1 to 20 carbon atoms which may have an oxygen atom between the carbon atoms, or an optionally substituted aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, or a heterocyclic group having 3 to 14 members. However, groups in which a substituted or unsubstituted amino group is bonded to a phenyl group are excluded. R ²⁰¹ to R ²⁰⁶ and R ²²¹ to R ²²⁶ are each independently preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms. R ²⁰⁷ to R ²¹⁸ and R ²²⁷ to R ²³⁸ may each independently be the same as R ²⁰⁷ to R ²¹⁸ and R ²²⁷ to R ²³⁸ in formula (A1) and formula (A2).

In formula (A1b), Q ¹ , Q ² and Q ³ represent divalent groups formed when R ²⁰¹ and R ²⁰² , R ²⁰³ and R ²⁰⁴ , and R ²⁰⁵ and R ²⁰⁶ in formula (A1) are bonded to each other to form, together with the nitrogen atom to which these groups were bonded, a heterocycle having 3 to 8 members. In formula (A2b), Q ¹¹ , Q ¹² and Q ¹³ represent divalent groups formed when R ²²¹ and R ²²² , R ²²³ and R ²²⁴ , and R ²²⁵ and R ²²⁶ in formula (A2) are bonded to each other to form, together with the nitrogen atom to which these groups were bonded, a heterocycle having 3 to 8 members.

Formula (A1b) and Formula (A2b) may each have at least one of Q ¹ to Q ³ and Q ¹¹ to Q ¹³ , and may have two or more, or even three. The hydrogen atoms bonded to Q ¹ to Q ³ and Q ¹¹ to Q ¹³ may be independently substituted with an alkyl group having 1 to 12 carbon atoms.

It is preferable that Q ¹ to Q ³ and Q ¹¹ to Q ¹³ are each independently an alkylene group represented by —(CH ₂ ) _n1 — (n1 is an integer of 2 to 7), and a hydrogen atom of the alkylene group may be substituted by an alkyl group having 1 to 12 carbon atoms.

When no heterocycle is formed, R ²⁰¹ to R ²⁰⁶ and R ²²¹ to R ²²⁶ can each independently be the same as R ²⁰¹ to R ²⁰⁶ and R ²²¹ to R ²²⁶ in formula (A1a) and formula (A2a). R ²⁰⁷ to R ²¹⁸ and R ²²⁷ to R ²³⁸ can each independently be the same as R ²⁰⁷ to R ²¹⁸ and R ²²⁷ to R ²³⁸ in formula (A1) and formula (A2).

In formula (A1c), Q ⁴ to Q ⁹ each represent a divalent group formed when R ²⁰¹ and R ²⁰⁷ , R ²⁰² and R ²¹⁰ , R ²⁰³ and R ²¹¹ , R ²⁰⁴ and R ²¹⁴ , R ²⁰⁵ and R ²¹⁵ , and R ²⁰⁶ and R ²¹⁸ are bonded to form a 4-8 membered heterocycle together with the nitrogen atom to which these groups are bonded and the carbon atom of the phenyl group. In formula (A2c), ^Q to Q ^each represent a divalent group formed by combining R ²²¹ and R ²²⁷ , R ²²² and R ²³⁰ , R ²²³ and R ²³¹ , R ²²⁴ and R ²³⁴ , R ²²⁵ and R ²³⁵ , and R ²²⁶ and R ²³⁸ together with the nitrogen atom to which these groups are bonded and the carbon atom of the phenyl group to form a 4-8-membered heterocycle.

Formula (A1c) and Formula (A2c) may each have at least one of ^Q4 to ^Q9 and ^Q14 to ^Q19 , and may have two or more, or up to 6. The hydrogen atoms bonded to ^Q4 to ^Q9 and ^Q14 to ^Q19 may be independently substituted with an alkyl group having 1 to 12 carbon atoms.

It is preferable that Q ⁴ to Q ⁹ and Q ¹⁴ to Q ¹⁹ are each independently an alkylene group represented by —(CH ₂ ) _n2 — (n2 is an integer of 1 to 5), and a hydrogen atom of the alkylene group may be substituted by an alkyl group having 1 to 12 carbon atoms.

When no heterocycle is formed, R ²⁰¹ to R ²¹⁸ and R ²²¹ to R ²³⁸ may each independently be the same as R ²⁰¹ to R ²¹⁸ and R ²²¹ to R ²³⁸ in formula (A1) and formula (A2).

More specifically, dye (A1a) and dye (A2a) include compounds in which R ²⁰¹ to R ²¹⁸ and R ²²¹ to R ²³⁸ are shown in Tables 1 and 2, respectively. In the exemplified dye (A1a), R ²⁰¹ , R ²⁰³ , and R ²⁰⁵ have the same group, so they are shown together in one column in Table 1. ^{R 202} , R ²⁰⁴ , and R ²⁰⁶ are also shown together in the same manner. For R ²⁰⁷ to R ²¹⁸ , the substituents at the same position in the three phenyl groups bonded to the central nitrogen atom are collectively represented as "R ²⁰⁷ , R ²¹¹ , R ²¹⁵ ,""R ²⁰⁸ , R ²¹² , R ²¹⁶ ,""R ²⁰⁹ , R ²¹³ , R ²¹⁷ ," and "R ²¹⁰ , R ²¹⁴ , R ²¹⁸ ." The same notation is used for dye (A2a).

In Table 1, for dye (A1a-21) and dye (A1a-23), the divalent groups formed by bonding three adjacent pairs of two groups, R ²⁰⁷ and R ²⁰⁸ , R ²¹¹ and R ²¹² , and R ²¹⁵ and R ²¹⁶ , are shown in the column linking "R ²⁰⁷ , R ²¹¹ , R ^{215 ,} " and the column linking "R ²⁰⁸ , R ²¹² , R ²¹⁶ ." For dye (A1a-22), the divalent groups formed by bonding three adjacent pairs of two groups, R ²⁰⁹ and R ²¹⁰ , R ²¹³ and R ²¹⁴ , and R ²¹⁷ and R ²¹⁸ , respectively, are described in the column combining "R ²⁰⁹ , R ²¹³ , R ²¹⁷ " and "R ²¹⁰ , R ²¹⁴ , R ²¹⁸ ". The same description method is used for dye (A2a-21), dye (A2a-22), and dye (A2a-23) in Table 2.

Tables 1 and 2 do not show Xa ^- and Xb ^- , but in all compounds, Xa ^- or Xb ^- is each independently Cl ^- , Br ^- , I ^- , F ^- , ClO ₄ ^- , BF ₄ ^- , PF ₆ ^- , SbF ₆ ^- , CF ₃ SO ₃ ^- , CH ₃ C ₆ H ₄ SO ₃ ^- , N[SO ₂ R _f ] ₂ ^- , or C[SO ₂ R _f ] ₃ ^- . Xa ^- and Xb ^- are each preferably independently I ^- , BF ^{4 -} , SbF ₆ ^- , PF ₆ ^- , ClO ₄ ^- , N[SO ₂ CF ₃ ] ₂ ^- or C[SO ₂ CF ₃ ] ₃ ^- .

The abbreviations for the dyes corresponding to the above-mentioned preferred monovalent anions are shown as follows: When Xa ^- in dye (A1a-1) is I ^- , it is shown as dye (A1a-1I), when it is BF ^{4 -} it is shown as dye (A1a-1B), when it is SbF ₆ ^- it is shown as dye (A1a-1Sb), when it is PF ₆ ^- it is shown as dye (A1a-1P), when it is ClO ₄ ^- it is shown as dye (A1a-1Cl), when it is N[SO ₂ CF ₃ ] ₂ ^- it is shown as dye (A1a-1NS), and when it is C[SO ₂ CF ₃ ] ₃ ^- it is shown as dye (A1a-1CS). The same applies to the other dyes shown in Tables 1 and 2. In Tables 1 and 2, Ph represents a phenyl group, and all alkyl groups such as -C ₃ H ₇ are linear alkyl groups.

More specific examples of the dye (A1b) include compounds in which Q ¹ to Q ³ and R ²⁰⁷ to R ²¹⁸ are shown in Table 3 below. In the exemplified dye (A1b), Q ¹ , Q ² , and Q ³ have the same groups, so in Table 3, these are shown together in one column. ^{R 207} to R ²¹⁸ are described in the same way as in Table 1. More specific examples of the dye (A2b) include compounds in which Q ¹¹ to Q ¹³ and R ²²⁷ to R ²³⁸ are shown in Table 4 below. In the exemplified dye (A2b), Q ¹¹ , Q ¹² , and Q ¹³ have the same groups, so in Table 4, these are shown together in one column. ^{R 227} to R ²³⁸ are described in the same way as in Table 2.

Tables 3 and 4 do not show Xa ^- and Xb ^- , but in all compounds, Xa ^- or Xb ^- is the same as that of dye (A1a) shown in Table 1. In Tables 3 and 4, all alkyl groups such as -C ₄ H ₉ are linear alkyl groups.

More specifically, dye (A1c) includes compounds in which ^Q4 to ^Q9 , " ^R202 , ^R204 , ^R206 ", " ^R208 , ^R212 , ^R216 ", " ^R209 , ^R213 , ^R217 ", and " ^R210 , ^R214 , ^R218 " are shown in Table 5 below. In the exemplified dye (A1c), ^Q4 , ^Q6 , and ^Q8 have the same group, so these are shown together in one column in Table 5. Furthermore, when ^Q5 , ^Q7 , and ^Q9 are present, ^Q5 , ^Q7 , and ^Q9 have the same group, so these are shown together in one column in Table 5. "R ²⁰² , R ²⁰⁴ , R ²⁰⁶ " and "R ²¹⁰ , R ²¹⁴ , R ²¹⁸ " are groups that are present when the dye (A1c) does not have Q ⁵ , Q ⁷ , or Q ⁹ .

More specifically, dye (A2c) includes compounds in which Q ¹⁴ to Q ¹⁹ , "R ²²² , R ²²⁴ , R ²²⁶ ,""R ²²⁸ , R ²³² , R ^{236 ,} ""R ²²⁹ , R ²³³ , R ²³⁷ ," and "R ²³⁰ , R ²³⁴ , R ²³⁸ " are shown in Table 6 below. In the exemplified dye (A2c), Q ¹⁴ , Q ¹⁶ , and Q ¹⁸ have the same group, so these are shown together in one column in Table 6. Furthermore, when Q ¹⁵ , Q ¹⁷ , and Q ¹⁹ are present, Q ¹⁵ , Q ¹⁷ , and Q ¹⁹ have the same group, so these are shown together in one column in Table 6. "R ²²² , R ²²⁴ , R ²²⁶ " and "R ²³⁰ , R ²³⁴ , R ²³⁸ " are groups that are present when the dye (A2c) does not have Q ¹⁵ , Q ¹⁷ , or Q ¹⁹ .

" ^R202 , ^R204 , ^R206 ", " ^R208 , ^R212 , ^R216 ", " ^R209 , ^R213 , ^R217 ", and " ^R210 , ^R214 , ^R218 " are described in the same way as in Table 1. " ^R222 , ^R224 , ^R226 ", " ^R228 , ^R232 , ^R236 ", " ^R229 , ^R233 , ^R237 ", and " ^R230 , ^R234 , ^R238 " are described in the same way as in Table 2.

In addition, in dye (A1c) and dye (A2c), compounds that are symmetrical on the left and right, for example, dye (A1c-1) and a compound in which "Q ⁵ , Q ⁷ , Q ⁹ " are -CH ₂ -CH ₂ -CH ₂ -CH ₂ -, "R ²⁰¹ , R ²⁰³ , R ²⁰⁵ " are -C ₂ H ₅ , and "R ²⁰⁷ , R ²¹¹ , R ²¹⁵ ", "R ²⁰⁸ , R ²¹² , R ²¹⁶ ", and "R ²⁰⁹ , R ²¹³ , R ²¹⁷ " are H, are treated as the same compound.

Tables 5 and 6 do not show ^Xa- and ^Xb- , but in all compounds, ^Xa- or ^Xb- is the same as that for dye (A1a) shown in Table 1. In Tables 5 and ₆ , all alkyl groups such as _-C3H7 are linear alkyl groups. In addition, in Tables 5 and 6, the divalent groups shown in the columns " ^Q4 , ^Q6 , ^Q8 ,"" ^Q5 , ^Q7 , ^Q9 ,"" ^Q14 , ^Q16 , ^Q18 ," and " ^Q15 , ^Q17 , ^Q19 " are in an embodiment where the left side is bonded to a nitrogen atom and the right side is bonded to a carbon atom of a phenyl group.

As the dye (A1), among these, dye (A1a) such as dye (A1a-5Sb), dye (A1a-5NS), dye (A1a-5P), dye (A1a-5Cl), dye (A1a-5B), dye (A1a-1NS), dye (A1a-4Sb), dye (A1a-4NS), dye (A1a-4P), dye (A1a-7NS), dye (A1a-7P), etc. are preferred, and dye (A1a-5Sb), dye (A1a-5NS), dye (A1a-5P), dye (A1a-4Sb), dye (A1a-4NS), and dye (A1a-4P) are more preferred.

Furthermore, as the dye (A1b), dye (A1b-1Sb), dye (A1b-1NS), dye (A1b-1P), etc. are preferred. As the dye (A1c), dye (A1c-3NS), dye (A1c-3P), dye (A1c-4NS), dye (A1c-4P), dye (A1c-10NS), dye (A1c-10P), etc. are preferred, and dye (A1b-1NS), dye (A1c-1NS), dye (A1c-4NS), dye (A1c-4P), dye (A1c-10NS), dye (A1c-10P) are more preferred.

As the dye (A2), among these, dye (A2a) such as dye (A2a-5Sb), dye (A2a-5NS), dye (A2a-5P), dye (A2a-5Cl), dye (A2a-5B), dye (A2a-1NS), dye (A2a-4Sb), dye (A2a-4NS), dye (A2a-4P), dye (A2a-7NS), and dye (A2a-7P) are preferred, with dye (A2a-5Sb), dye (A2a-5NS), dye (A2a-5P), dye (A2a-4Sb), dye (A2a-4NS), and dye (A2a-4P) being more preferred.

Furthermore, as the dye (A2b), dye (A2b-1Sb), dye (A2b-1NS), dye (A2b-1P), etc. are preferred. As the dye (A2c), dye (A2c-3NS), dye (A2c-3P), dye (A2c-4NS), dye (A2c-4P), dye (A2c-10NS), dye (A2c-10P), etc. are preferred, and dye (A2b-1NS), dye (A2b-1NS), dye (A2c-4NS), dye (A2c-4P), dye (A2c-10NS), dye (A2c-10P) are more preferred.

NIR dye (A) may consist of one type of compound, or two or more types of compounds. When consisting of two or more types of compounds, each individual compound does not necessarily have to have the properties of NIR dye (A); the mixture as a whole must have the properties of NIR dye (A).

Dye (A1) and dye (A2) can each be produced by a known method. Dye (A1a) to dye (A1c) can be produced, for example, by the method described in JP 2007-197492 A. Dye (A2a) to dye (A2c) can be produced, for example, by the method described in JP 2009-221146 A.

[NIR dye (B)]
The NIR dye (B) is a dye that has a maximum absorption wavelength λ _max(B)TR in the wavelength region of 1100 to 1200 nm in the spectral transmittance curve of 350 to 1200 nm measured when incorporated into the transparent resin (P). The maximum absorption wavelength λ _max(B)TR is preferably in the wavelength region of 1100 to 1150 nm.

It is also preferable that the NIR dye (B) has high visible transmittance in the resin.

The molecular structure of the NIR dye (B) is not particularly limited as long as the maximum absorption wavelength λmax _(B)TR is in the range of 1100 to 1200 nm. Specific examples include at least one dye selected from the group consisting of cyanine dyes, croconium dyes, phthalocyanine dyes, squarylium dyes, diimonium dyes, diketopyrrolopyrrole dyes, metal complex dyes, and metal oxides. Diimonium dyes are particularly preferred from the viewpoint of high visible light transmittance.

Specific examples of the diimonium dye that is the NIR dye (B) include one or more compounds selected from the group consisting of compounds represented by the following formula (B1) and compounds represented by the following formula (B2):

The symbols in formulas (B1) and (B2) are as follows:
R ²⁴¹ to R ²⁴⁸ and R ²⁶¹ to R ²⁶⁸ are each independently a hydrogen atom, a halogen atom, a sulfo group, a hydroxy group, a cyano group, a nitro group, a carboxyl group, a phosphate group, an alkyl group or alkoxy group having 1 to 20 carbon atoms which may have an unsaturated bond or an oxygen atom between carbon atoms and which may be substituted, or an aryl group having 6 to 14 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, or a heterocyclic group having 3 to 14 members, which may be substituted. In R ²⁴¹ to R ²⁴⁸ and R ²⁶¹ to R ²⁶⁸ , two groups bonded to the same nitrogen atom may bond to each other to form a heterocyclic ring having 3 to 8 members together with the nitrogen atom, and a hydrogen atom bonded to the ring may be substituted by an alkyl group having 1 to 12 carbon atoms.

In R ²⁴¹ to R ²⁴⁸ and R ²⁶¹ to R ²⁶⁸ , examples of the substituent in the optionally substituted alkyl or alkoxy group having 1 to 20 carbon atoms, the optionally substituted aryl group having 6 to 14 carbon atoms, the aralkyl group having 7 to 14 carbon atoms, or the heterocyclic group having 3 to 14 members include a halogen atom, a hydroxyl group, an amino group which may be substituted with an alkyl group having 1 to 6 carbon atoms, a carboxyl group, a sulfo group, a cyano group, and an acyloxy group having 1 to 6 carbon atoms.

When no ring is formed, R ²⁴¹ to R ²⁴⁸ and R ²⁶¹ to R ²⁶⁸ are each independently preferably an alkyl group or alkoxy group having 1 to 12 carbon atoms. The alkyl group or alkoxy group preferably has 1 to 8 carbon atoms.

R ²⁴¹ to R ²⁴⁸ and R ²⁶¹ to R ²⁶⁸ are preferably linear or branched alkyl groups having 4 to 6 carbon atoms from the following viewpoint: By making the number of carbon atoms 4 or more, solubility in organic solvents becomes good, and by making the number of carbon atoms 6 or less, heat resistance is improved. The reason for the improved heat resistance is thought to be that the melting point of the dye increases.

The divalent group formed when two groups bonded to the same nitrogen atom are bonded to each other, i.e., when R ²⁴¹ and R ²⁴² , R ²⁴³ and R ²⁴⁴ , R ²⁴⁵ and R ²⁴⁶ , and R ²⁴⁷ and R ²⁴⁸ are bonded to each other, is preferably an alkylene group represented by —(CH ₂ ) _n3 — (n3 is an integer of 2 to 7), and the hydrogen atom of the alkylene group may be substituted by an alkyl group having 1 to 12 carbon atoms.

R ²⁴⁹ to R ²⁵³ and R ²⁶⁹ to R ²⁷³ are each independently a hydrogen atom, a halogen atom, an optionally substituted amino group, an amido group, a cyano group, a nitro group, a carboxyl group, or an alkyl or alkoxy group having 1 to 12 carbon atoms which may be substituted with a halogen atom. Each of the four R ²⁴⁹ to R ²⁵³ and R ²⁶⁹ to R ²⁷³ may be the same or different.

It is preferable that R ²⁴⁹ to R ²⁵³ and R ²⁶⁹ to R ²⁷³ each independently represent a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 12 carbon atoms. The alkyl or alkoxy group preferably has 1 to 6 carbon atoms, and more preferably 1 to 4 carbon atoms.

Xc ^- and Xd ^- each independently represent a monovalent anion. Examples of Xc ^- and Xd ^- include Cl ^- , Br ^- , I ^- , F ^- , ClO ₄ ^- , BF ₄ ^- , PF ₆ ^- , SbF ₆ ^- , CF ₃ SO ₃ ^- , CH ₃ C ₆ H ₄ SO ₃ ^- , N[SO ₂ R _f ] ₂ ^- , and C[SO ₂ R _f ] ₃ ^- . Among these, PF ₆ ^- , N[SO ₂ R _f ] ₂ ^- , and C[SO ₂ R _f ] ₃ ^- are preferred, and PF ₆ ^- and N[SO ₂ R _f ] ₂ ^- are more preferred.

Here, _Rf can be the same as in the above-mentioned ^Xa- and ^Xb- , including preferred embodiments.

More specifically, examples of dye (B1) and dye (B2) include compounds in which R ²⁴¹ to R ²⁵³ and R ²⁶¹ to R ²⁷³ are shown in Tables 7 and 8 below, respectively. In the exemplified dye (B1), R ²⁴¹ , R ²⁴³ , R ²⁴⁵ , and R ²⁴⁷ have the same group, so in Table 7, these are shown together in one column. The same is true for ^{R 242} , R ²⁴⁴ , R ²⁴⁶ , and R ^248. R ²⁴⁹ ₄ to R ²⁵³ ₄ indicate that R ²⁴⁹ to R ²⁵³ each have four groups or atoms, and when the four groups or atoms are the same, only one of those groups or atoms is shown. When they are different, the four atoms or groups are shown as "H, H, H, -CH ₃ ". The bonding positions of the atoms or groups are not specified. For example, "H,H,H,-CH ₃ " indicates that -CH ₃ is bonded to any of the four carbon atoms other than the carbon atom to which the nitrogen atom of the benzene ring is bonded.

In Table 7, dye (B1-6) represents a case where R ²⁴¹ and R ²⁴² , R ²⁴³ and R ²⁴⁴ , R ²⁴⁵ and R ²⁴⁶ , and R ²⁴⁷ and R ²⁴⁸ are bonded to each other to form —CH ₂ —CH ₂ —CH ₂ —CH ₂ —. The same description method for dye (B1) in Table 7 was also applied to dye (B2) in Table 8.

Tables 7 and 8 do not show Xc ^- and Xd ^- , but in all compounds, Xc ^- or Xd ^- is each independently Cl ^- , Br ^- , I ^- , F ^- , ClO ₄ ^- , BF ₄ ^- , PF ₆ ^- , SbF ₆ ^- , CF ₃ SO ₃ ^- , CH ₃ C ₆ H ₄ SO ₃ ^- , N[SO ₂ R _f ] ₂ ^- , or C[SO ₂ R _f ] ₃ ^- . Xc ^- and Xd ^- are each preferably independently I ^- , BF ^{4 -} , SbF ₆ ^- , PF ₆ ^- , ClO ₄ ^- , N[SO ₂ CF ₃ ] ₂ ^- or C[SO ₂ CF ₃ ] ₃ ^- .

The abbreviations for dyes corresponding to the above-mentioned preferred monovalent anions are shown as follows. For example, when Xc ^- in dye (B1-1) is I ^- , it is shown as dye (B1-1I), when it is BF ^{4 -} it is shown as dye (B1-1B), when it is SbF ₆ ^- it is shown as dye (B1-1Sb), when it is PF ₆ ^- it is shown as dye (B1-1P), when it is ClO ₄ ^- it is shown as dye (B1-1Cl), when it is N[SO ₂ CF ₃ ] ₂ ^- it is shown as dye (B1-1NS), and when it is C[SO ₂ CF ₃ ] ₃ ^- it is shown as dye (B1-1CS). The same applies to the other dyes shown in Tables 7 and 8. In Tables 7 and 8, Ph represents a phenyl group, and all alkyl groups such as -C ₃ H ₇ are linear alkyl groups.

Of these, dye (B1) is preferably dye (B1-5NS), dye (B1-5Sb), dye (B1-5P), dye (B1-4NS), dye (B1-4Sb), dye (B1-4P), etc. Among these, dye (B2) is preferably dye (B2-4NS), dye (B2-4P), dye (B2-5NS), dye (B2-5P), etc.

NIR dye (B) may consist of one type of compound, or two or more types of compounds. When consisting of two or more types of compounds, each individual compound does not necessarily have the properties of NIR dye (B); the mixture as a whole must have the properties of NIR dye (B).

Dye (B1) and dye (B2) can each be produced by a known method. Dye (B1) can be produced, for example, by the method described in JP-A-2009-137894. Dye (B2) can be produced, for example, by the method described in JP-A-2000-229931.

Commercially available examples of dye (B1) include Kayasorb IRG-022, IRG-023, IRG-024, IRG-068, IRG-069, and IRG-079 manufactured by Nippon Kayaku Co., Ltd., and CIR-1081, CIR-1083, CIR-1085, and CIR-RL (all trade names) manufactured by Nippon Carlit Co., Ltd.

[NIR dye (C)]
The NIR dye (C) is a squarylium dye having a maximum absorption wavelength λ _max(C)TR in the wavelength region of 630 to 750 nm in the spectral transmittance curve of 350 to 1200 nm measured when incorporated into the transparent resin (P). The maximum absorption wavelength λ _max(C)TR is preferably in the wavelength region of 650 to 740 nm.

Furthermore, the NIR dye (C) preferably has a high visible transmittance in the resin, and exhibits a steep rise in transmittance from the maximum absorption wavelength λ _{max (C) TR} to the shorter wavelength side.

The NIR dye (C) is not particularly limited as long as it is a squarylium dye that satisfies the requirement of maximum absorption wavelength λ _max(C)TR . More specifically, the NIR dye (C) is preferably a squarylium dye represented by the following formula (I) or (II):

In the formula (I), the symbols are as follows:
R ²⁴ and R ²⁶ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl or alkoxy group having 1 to 20 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, an aryl group having 6 to 11 carbon atoms, an aralkyl group having 7 to 18 carbon atoms which may have a substituent and an oxygen atom between the carbon atoms, -NR ²⁷ R ²⁸ (R ²⁷ and R ²⁸ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, -C(═O)-R ²⁹ (R ²⁹ is a hydrogen atom, a halogen atom, a hydroxyl group, a hydrocarbon group having 1 to 25 carbon atoms which may have a substituent and which may contain an unsaturated bond, an oxygen atom, or a saturated or unsaturated ring structure between the carbon atoms), -NHR ³⁰ , or -SO ₂ -R ³⁰ (R ³⁰ represents a hydrocarbon group having 1 to 25 carbon atoms, in which one or more hydrogen atoms may be substituted with a halogen atom, a hydroxyl group, a carboxyl group, a sulfo group, or a cyano group, and which may contain an unsaturated bond, an oxygen atom, or a saturated or unsaturated ring structure between carbon atoms), or a group represented by the following formula (S) (R ⁴¹ and R ⁴² independently represent a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group having 1 to 10 carbon atoms, and k is 2 or 3):

R ²¹ and R ²² , R ²² and R ²⁵ , and R ²¹ and R ²³ may be bonded to each other to form, together with the nitrogen atom, a 5- or 6-membered heterocycle A, heterocycle B, and heterocycle C, respectively.

When heterocycle A is formed, R ²¹ and R ²² bond to form a divalent group -Q-, which is an alkylene group or alkyleneoxy group in which the hydrogen atom may be substituted with an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an acyloxy group having 1 to 10 carbon atoms which may have a substituent.

R ²² and R ²⁵ when heterocycle B is formed, and R ²¹ and R ²³ when heterocycle C is formed, are bonded to divalent groups -X ¹ -Y ¹ - and -X ² -Y ² - (X ¹ and X ² are the sides bonded to the nitrogen), where X ¹ and X ² are each a group represented by the following formula (1x) or (2x), and Y ¹ and Y ² are each a group selected from the following formulas (1y) to (5y). When ^{X 1} and X ² are each a group represented by the following formula (2x), Y ¹ and Y ² may each be a single bond, in which case there may be an oxygen atom between the carbon atoms.

In formula (1x), four Z's each independently represent a hydrogen atom, a hydroxyl group, an alkyl group or alkoxy group having 1 to 6 carbon atoms, or -NR ³⁸ R ³⁹ (R ³⁸ and R ³⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms). ^{R 31} to R ³⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and R ³⁷ represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms.

R ²⁷ , R ²⁸ , R ²⁹ , R ³¹ to R ³⁷ , R ²¹ to R ²³ when they do not form a heterocycle, and R ²⁵ may be bonded to any of the others to form a 5- or 6-membered ring. R ³¹ and R ³⁶ , and R ³¹ and R ³⁷ may be directly bonded to each other.

When no heterocycle is formed, R ²¹ , R ²² , R ²³ and R ²⁵ each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group or alkoxy group having 1 to 20 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, an aryl group having 6 to 11 carbon atoms, or an aralkyl group having 7 to 18 carbon atoms which may have a substituent and which may have an oxygen atom between the carbon atoms.

In formula (I), unless otherwise specified, the hydrocarbon group is an alkyl group, an aryl group, or an aralkyl group. Unless otherwise specified, the alkyl group and the alkyl portion of the alkoxy group, aryl group, or aralkyl group may be linear, branched, cyclic, or a combination of these structures.

The same applies to the alkyl groups, alkoxy groups, aryl groups, and aralkyl groups in the other formulae below. In formula (I), examples of the substituent for R ²⁹ include a halogen atom, a hydroxyl group, a carboxyl group, a sulfo group, a cyano group, and an acyloxy group having 1 to 6 carbon atoms. Examples of the substituent when it is stated that "may have a substituent" other than R ²⁹ include a halogen atom or an alkoxy group having 1 to 15 carbon atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a fluorine atom and a chlorine atom being preferred.

Here, the symbols in formula (II) are as follows:
Ring Z is independently a 5- or 6-membered ring having 0 to 3 heteroatoms in the ring, and a hydrogen atom of ring Z may be substituted. When a hydrogen atom is substituted, examples of the substituent include a halogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent.

The carbon atoms or hetero atoms constituting ^R1 and ^R2 , ^R2 and ^R3 , and ^R1 and ring Z may be bonded to each other to form heterocycle A1, heterocycle B1, and heterocycle C1 together with the nitrogen atom, respectively, and in this case, the hydrogen atoms in heterocycle A1, heterocycle B1, and heterocycle C1 may be substituted. When a hydrogen atom is substituted, examples of the substituent include a halogen atom or an alkyl group having 1 to 15 carbon atoms which may have a substituent.

When no heterocycle is formed, ^R1 and ^R2 each independently represent a hydrogen atom, a halogen atom, or a hydrocarbon group which may contain an unsaturated bond, a heteroatom, or a saturated or unsaturated ring structure between carbon atoms and which may have a substituent. ^R4 and ^R3 when no heterocycle is formed each independently represent a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group which may contain a heteroatom between carbon atoms and which may have a substituent.

In formula (II), the hydrocarbon group may have 1 to 15 carbon atoms. The alkyl group or alkoxy group may have 1 to 10 carbon atoms. In formula (II), when it says "may have a substituent," examples of the substituent include a halogen atom or an alkoxy group having 1 to 10 carbon atoms. Examples of halogen atoms include a fluorine atom, chlorine atom, bromine atom, and iodine atom, with fluorine and chlorine atoms being preferred.

Examples of compound (I) include compounds represented by any of formulas (I-1) to (I-4).

However, the symbols in formulas (I-1) to (I-4) have the same definitions as those of the same symbols in formula (I), and the preferred embodiments are also the same.

Of the compounds (I-1) to (I-4), compounds (I-1) to (I-3) are preferred as the NIR dye (C) from the viewpoint of increasing the visible light transmittance of the resin layer containing them, with compound (I-1) being particularly preferred.

In compound (I-1), X ¹ is preferably a group (2x), and Y ¹ is preferably a single bond or a group (1y). In this case, R ³¹ to R ³⁶ are preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or a methyl group. Specific examples of -Y ¹ -X ¹ - include divalent organic groups represented by formulas (11-1) to (12-3).

-C(CH ₃ ) ₂ -CH(CH ₃ )-...(11-1)
-C( _CH3 ) ₂ - _CH2 -...(11-2)
-C( _CH3 ) ₂ -CH( _C2H5 )-... ₍ 11-3)
-C( _CH3 ) ₂ -C( _CH3 )( _nC3H7 )-...( _11-4 )
-C( _CH3 ) ₂ - _CH2 - _CH2 -...(12-1)
-C(CH ₃ ) ₂ -CH ₂ -CH(CH ₃ )-...(12-2)
-C( _CH3 ) ₂ -CH( _CH3 ) _-CH2 -...(12-3)

In addition, in compound (I-1), R ²¹ is more preferably independently a group represented by formula (4-1) or formula (4-2), from the viewpoints of solubility, heat resistance, and the steepness of the change in the spectral transmittance curve near the boundary between the visible region and the near-infrared region.

In formula (4-1) and formula (4-2), R ⁸¹ to R ⁸⁵ independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms.

In compound (I-1), R ²⁴ is preferably —NR ²⁷ R ^28. As —NR ²⁷ R ²⁸ , —NH—C(═O)—R ²⁹ is preferred from the viewpoint of solubility in the resin to be combined with NIR dye (C) and in the solvent used when forming a resin layer on a substrate. A compound in which R ²⁴ is —NH—C(═O)—R ²⁹ in compound (I-1) is shown in formula (I-11).

In the compound (I-11), R ²³ and R ²⁶ are preferably each independently a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 6 carbon atoms, and more preferably a hydrogen atom.

In compound (I-11), R ²⁹ is preferably an alkyl group having 1 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 10 carbon atoms which may have a substituent, or an aralkyl group having 7 to 18 carbon atoms which may have a substituent and which may have an oxygen atom between the carbon atoms. Examples of the substituent include a halogen atom such as a fluorine atom, a hydroxyl group, a carboxyl group, a sulfo group, a cyano group, an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and an acyloxy group having 1 to 6 carbon atoms.

R ²⁹ is preferably a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group or alkoxy group having 1 to 20 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, an aryl group having 6 to 11 carbon atoms, or an aralkyl group having 7 to 18 carbon atoms which may have a substituent and which may have an oxygen atom between the carbon atoms.

R ²⁹ is preferably a group selected from a linear, branched or cyclic alkyl group having 1 to 17 carbon atoms which may be substituted with a fluorine atom, a phenyl group which may be substituted with a fluoroalkyl group having 1 to 6 carbon atoms and/or an alkoxy group having 1 to 6 carbon atoms, and an aralkyl group having 7 to 18 carbon atoms which may have an oxygen atom between the carbon atoms and which has a phenyl group which may be substituted with an alkyl group having 1 to 6 carbon atoms which may be substituted with a fluorine atom at the terminal and/or an alkoxy group having 1 to 6 carbon atoms.

R ²⁹ may also preferably be a hydrocarbon group having 5 to 25 carbon atoms and at least one branch, in which one or more hydrogen atoms may be independently substituted with a halogen atom, a hydroxyl group, a carboxyl group, a sulfo group, or a cyano group, and which may contain an unsaturated bond, an oxygen atom, or a saturated or unsaturated ring structure between carbon atoms. Examples of such R ²⁹ include groups represented by the following formulas (11a), (11b), (12a) to (12e), and (13a) to (13e).

More specifically, examples of compound (I-11) include the compounds shown in Table 9 below. In Table 9, group (11-1) is represented as (11-1). The same applies to other groups. Groups are represented in the same way in the other tables below. In addition, in all of the compounds shown in Table 9, the symbols on the left and right of the squarylium skeleton have the same meaning. The same applies to the squarylium dyes shown in the other tables below.

In compound (I-1), from the viewpoint of increasing the transmittance of visible light, particularly the transmittance of light with a wavelength of 430 to 550 nm, R ²⁴ is preferably —NH—SO ₂ —R ^30. Compound (I-1) in which R ²⁴ is —NH—SO ₂ —R ³⁰ is represented by formula (I-12).

In the compound (I-12), R ²³ and R ²⁶ are preferably each independently a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 6 carbon atoms, and more preferably a hydrogen atom.

In compound (I-12), from the viewpoint of light resistance, R ³⁰ is preferably independently an alkyl or alkoxy group having 1 to 12 carbon atoms, which may be branched, or a hydrocarbon group having 6 to 16 carbon atoms and an unsaturated ring structure. Examples of unsaturated ring structures include benzene, toluene, xylene, furan, and benzofuran. R ³⁰ is more preferably independently an alkyl or alkoxy group having 1 to 12 carbon atoms, which may be branched. In each group represented by R ³⁰ , some or all of the hydrogen atoms may be substituted with halogen atoms, particularly fluorine atoms. The substitution of hydrogen atoms with fluorine atoms is to an extent that does not reduce the adhesion between a resin layer containing dye (I-12) and, for example, a transparent substrate.

Specific examples of R ³⁰ having an unsaturated ring structure include groups represented by the following formulae (P2), (P3), (P7), (P8), and (P10) to (P13).

More specifically, examples of compound (I-12) include the compounds shown in Table 10 below.

Examples of compound (II) include compounds represented by any of formulas (II-1) to (II-3).

In formula (II-1) and formula (II-2), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 15 carbon atoms which may have a substituent, and R ³ to R ⁶ each independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 10 carbon atoms which may have a substituent.

In formula (II-3), R ¹ , R ⁴ , and R ⁹ to R ¹² each independently represent a hydrogen atom, a halogen atom, or an optionally substituted alkyl group having 1 to 15 carbon atoms, and R ⁷ and R ⁸ each independently represent a hydrogen atom, a halogen atom, or an optionally substituted alkyl group having 1 to 5 carbon atoms.

In compounds (II-1) and (II-2), from the viewpoints of solubility in resins, visible light transmittance, and the like, R ¹ and R ² are preferably independently an alkyl group having 1 to 15 carbon atoms, more preferably an alkyl group having 7 to 15 carbon atoms, still more preferably at least one of R ¹ and R ² is an alkyl group having a branched chain having 7 to 15 carbon atoms, and particularly preferably both of R ¹ and R ² are alkyl groups having a branched chain having 8 to 15 carbon atoms.

From the viewpoints of solubility in resins, visible light transmittance, etc., ^R3 is preferably independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom, a halogen atom, or a methyl group. From the viewpoint of the steepness of the change near the boundary between the visible region and the near-infrared region, ^R4 is preferably a hydrogen atom or a halogen atom, particularly preferably a hydrogen atom. ^R5 in compound (II-1) and ^R6 in compound (II-2) are each independently preferably a hydrogen atom, a halogen atom, or an alkyl group having 1 to 5 carbon atoms which may be substituted with a halogen atom, more preferably a hydrogen atom, a halogen atom, or a methyl group.

More specifically, compound (II-1) and compound (II-2) include the compounds shown in Tables 11 and 12 below, respectively. In Tables 11 and 12, —C ₈ H ₁₇ , —C ₄ H ₉ , and —C ₆ H ₁₃ represent linear octyl, butyl, and hexyl groups, respectively.

In compound (II-3), from the viewpoints of solubility in resin, visible light transmittance, and the like, R ¹ is preferably independently an alkyl group having 1 to 15 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and particularly preferably an ethyl group or an isopropyl group.

From the viewpoints of visible light transmittance and ease of synthesis, ^R4 is preferably a hydrogen atom or a halogen atom, and particularly preferably a hydrogen atom. ^R7 and ^R8 are each preferably a hydrogen atom, a halogen atom, or an alkyl group having 1 to 5 carbon atoms which may be substituted with a halogen atom, and more preferably a hydrogen atom, a halogen atom, or a methyl group.

Preferably, R ⁹ to R ¹² are independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 5 carbon atoms which may be substituted by a halogen atom. Examples of —CR ⁹ R ¹⁰ —CR ¹¹ R ¹² — include the above groups (11-1) to (11-3) or a divalent organic group represented by the following formula (11-5):
-C( _CH3 )( _CH2 -CH( _CH3 ) ₂ )-CH( _CH3 )-...(11-5)

More specifically, examples of compound (II-3) include the compounds shown in Table 13 below.

Of these, dye (I-11) and dye (I-12) are preferred as the NIR dye (C) from the viewpoints of solubility in resins and solvents and visible light transmittance, with dye (I-11) shown in Table 9 and dye (I-12) shown in Table 10 being more preferred. Furthermore, of these, dye (I-11-7), dye (I-12-2), dye (I-12-9), dye (I-12-15), dye (I-12-23), dye (I-12-24), etc. are preferred.

NIR dye (C) may consist of one type of compound, or two or more types of compounds. When consisting of two or more types of compounds, each individual compound does not necessarily have to have the properties of NIR dye (C); the mixture as a whole only needs to have the properties of NIR dye (C).

Compound (I) and compound (II) can each be produced by known methods. Regarding compound (I), compound (I-11) can be produced, for example, by the method described in U.S. Patent No. 5,543,086. Compound (I-12) can be produced, for example, by the methods described in U.S. Patent Application Publication No. 2014/0061505 and WO 2014/088063. Compound (II) can be produced by the method described in WO 2017/135359.

Specific examples of the UV dyes optionally contained in the absorption layer include oxazole-based, merocyanine-based, cyanine-based, naphthalimide-based, oxadiazole-based, oxazine-based, oxazolidine-based, naphthalic acid-based, styryl-based, anthracene-based, cyclic carbonyl-based, and triazole-based dyes. Of these, oxazole-based and merocyanine-based dyes are preferred. The absorption layer may contain one UV dye alone, or two or more UV dyes may be used in combination.

[Transparent resin (P)]
The transparent resin (P) has a Tg of 130°C or higher and satisfies the above (1-1) to (1-6) in relation to the NIR dye (A). It is preferable that the transparent resin (P) further satisfies one or more of the above (1-7) to (1-9) in relation to the NIR dye (A).

Tg is determined by DSC (Differential Scanning Calorimetry). If the Tg of the transparent resin (P) is 130°C or higher, the absorbing layer has excellent heat resistance, maintaining the optical properties of the NIR dye (A) even when used at high temperatures. Furthermore, in a preferred embodiment, deformation due to heat or stress is unlikely to occur, and the dielectric multilayer film in this filter has excellent adhesion. Tg is preferably 200°C or higher, and more preferably 250°C or higher. There is no particular upper limit for Tg, but from the perspective of moldability, etc., the Tg of the transparent resin (P) is preferably 400°C or lower.

The transparent resin (P) is not particularly limited in type as long as it has a Tg of 130°C or higher and satisfies the above requirements (1-1) to (1-6) in relation to the NIR dye (A). For example, one or more resins selected from acrylic resins, epoxy resins, ene-thiol resins, polycarbonate resins, polyether resins, polyarylate resins, polysulfone resins, polyethersulfone resins, polyparaphenylene resins, polyarylene ether phosphine oxide resins, polyimide resins, polyamide-imide resins, polyolefin resins, cycloolefin resins, and polyester resins can be used.

Among these, at least one selected from polyimide resin, polyester resin, polycarbonate resin, cycloolefin resin, and epoxy resin is preferred. From the viewpoint of adhesion to the dielectric multilayer film, polyimide resin is preferred, and polyimide resin with a Tg of 200°C or higher is particularly preferred.

Transparent resin (P) may consist of one type of resin, or two or more types of resin. When it consists of two or more types of resin, the properties of the individual resins do not necessarily need to meet the requirements for transparent resin (P) above; the mixture as a whole must meet the requirements for transparent resin (P).

Commercially available products may be used as the transparent resin (P). Examples of commercially available products include polyester resins such as OKP4HT, B-OKP-2, and OKP-850 (all of which are product names manufactured by Osaka Gas Chemicals Co., Ltd.).

Commercially available polycarbonate resins that can be used as the transparent resin (P) include FPC-0220 (trade name, manufactured by Mitsubishi Gas Chemical Company, Inc.), Panlite (registered trademark) SP3810 (trade name, manufactured by Teijin Limited), PURE-ACE (registered trademark) M5 (trade name, manufactured by Teijin Limited), and PURE-ACE S5 (trade name, manufactured by Teijin Limited).

Commercially available polyimide resins that can be used as the transparent resin (P) include varnish-form polyimide resins such as Neoprim (registered trademark) C-3650 (manufactured by Mitsubishi Gas Chemical Company, Inc., product name), Neoprim C-3G30 (manufactured by Mitsubishi Gas Chemical Company, Inc., product name), Neoprim C-3450 (manufactured by Mitsubishi Gas Chemical Company, Inc., product name), Neoprim P500 (manufactured by Mitsubishi Gas Chemical Company, Inc., product name), and JL-20 (manufactured by New Japan Chemical Co., Ltd., product name) (these polyimide resin varnishes may contain silica).

Commercially available cycloolefin resins that can be used as the transparent resin (P) include ARTON (registered trademark) F4520 (trade name, manufactured by JSR Corporation), ZEONEX (registered trademark) K26R, F52R, T62R, APEL (registered trademark) APL5014DP, and APL6015T (all trade names, manufactured by Mitsui Chemicals, Inc.).

From the viewpoint of maintaining sufficiently high transmittance of visible light, particularly green and red light, the absorption layer is preferably composed only of the above-mentioned essential dyes, NIR dye (A), optional dyes such as NIR dye (B), NIR dye (C), and UV dye, and a transparent resin (P).

However, the absorbing layer may contain optional components such as adhesion promoters, color correction dyes, leveling agents, antistatic agents, heat stabilizers, light stabilizers, antioxidants, dispersants, flame retardants, lubricants, and plasticizers, as long as the effects of the present invention are not impaired.

When the average OD value is taken as 1 in a wavelength region of the maximum absorption wavelength λ _max(A)TR ±10 nm of the NIR dye (A), the absorbing layer preferably satisfies the following (2-1) and (2-2), more preferably satisfies one or more selected from (2-3) and (2-4), and particularly preferably satisfies all of (2-1) to (2-4):

(2-1) The average internal transmittance T _{AVE490-560 (AL)} in the wavelength region of 490 to 560 nm is 88% or more, preferably 90% or more, and more preferably 92% or more.

(2-2) The average internal transmittance T _{AVE590-630 (AL)} in the wavelength region of 590 to 630 nm is 70% or more, preferably 72% or more, and more preferably 75% or more.

(2-3) The wavelength λ _50% at which the internal transmittance is 50% is in the wavelength range of 600 to 700 nm, and the wavelength λ _50% is more preferably in the wavelength range of 610 to 640 nm.

(2-4) The total width of the wavelength range in the 600 to 1200 nm wavelength region where the internal transmittance is 30% or less is 250 nm or more. In the 600 to 1200 nm wavelength region, there may be one or more wavelength ranges in which the internal transmittance is 30% or less. The total width of the wavelength range in which the internal transmittance is 30% or less is preferably 250 nm or more, and more preferably 300 nm or more. The larger this total width, the higher the NIR absorption ability of the absorption layer.

The content of NIR dye (A) in the absorption layer is set appropriately to achieve the effects of the filter, depending on the design of the filter. From the viewpoint of blocking near-infrared light, particularly near-infrared light in the long wavelength range, while maintaining transmittance of visible light, particularly green and red light, the content of NIR dye (A) in the absorption layer is preferably 1 to 15 parts by mass per 100 parts by mass of transparent resin (P), and more preferably 1 to 10 parts by mass from the viewpoint of solubility.

When the absorption layer contains one or more NIR dyes selected from NIR dye (A) and NIR dye (B) and NIR dye (C), the content of each NIR dye is appropriately selected according to the design of the filter so that the absorption layer satisfies the characteristics (2-1) and (2-2), and preferably also satisfies one or more characteristics selected from (2-3) and (2-4).

In this case, the content of NIR dye (A) in the absorption layer is the same as above, and the content of one or more selected from NIR dye (B) and NIR dye (C) is preferably 1 to 15 parts by mass per 100 parts by mass of transparent resin (P) for each of NIR dye (B) and NIR dye (C) from the viewpoint of ensuring visible light transmittance while exhibiting the properties of NIR dye (B) and NIR dye (C), and more preferably 3 to 10 parts by mass from the viewpoint of solubility. Furthermore, the total content of NIR dye (A) and one or more selected from NIR dye (B) and NIR dye (C) is preferably 2 to 30 parts by mass per 100 parts by mass of transparent resin (P), and more preferably 5 to 27 parts by mass from the viewpoint of solubility.

In this filter, the thickness of the absorbing layer is preferably 0.1 to 100 μm. If the absorbing layer consists of multiple layers, the total thickness of the layers is preferably 0.1 to 100 μm. If the thickness is less than 0.1 μm, the desired optical properties may not be fully achieved, and if the thickness is more than 100 μm, the flatness of the layer may decrease, resulting in in-plane variations in absorbance. The thickness of the absorbing layer is more preferably 0.3 to 50 μm. Furthermore, if other functional layers such as a reflective layer or anti-reflective layer are provided, cracks may occur if the absorbing layer is too thick, depending on the material of the layer. Therefore, the thickness of the absorbing layer is more preferably 0.3 to 10 μm.

The absorption layer can be formed, for example, by dissolving or dispersing NIR dye (A), preferably one or more selected from NIR dye (A), NIR dye (B), and NIR dye (C), particularly preferably NIR dye (A), NIR dye (B), and NIR dye (C), transparent resin (P) or the raw materials for transparent resin (P), and other components blended as needed, in a solvent to prepare a coating solution, which is then applied to a substrate, dried, and optionally cured. The substrate may be the transparent substrate included in the filter, or a peelable substrate used only when forming the absorption layer. The solvent may be a dispersion medium in which the components can be stably dispersed or dissolved.

The coating liquid may also contain a surfactant to prevent voids caused by tiny bubbles, depressions caused by the adhesion of foreign matter, and repellency during the drying process. The coating liquid can be applied by, for example, dip coating, cast coating, or spin coating. After applying the coating liquid to the substrate, an absorbing layer is formed by drying. If the coating liquid contains raw materials for the transparent resin (P), it may be further subjected to a curing process such as heat curing or photocuring.

The absorption layer can also be manufactured into a film by extrusion molding, and this film can be laminated to another member and integrated by thermocompression or the like. For example, if the filter includes a transparent substrate, this film can be attached to the transparent substrate.

The filter may have one or more absorption layers. If two or more layers are present, the layers may have the same or different configurations. Furthermore, the absorption layer may consist of a single layer or a laminate of multiple layers. The absorption layer may also function as a substrate (resin substrate) itself.

(Transparent substrate)
When a transparent substrate is used in this filter, the material of the transparent substrate is not particularly limited as long as it transmits visible light of approximately 400 to 700 nm, and may be a material that absorbs near-infrared light or near-ultraviolet light, such as inorganic materials such as glass or crystal, or organic materials such as transparent resin.

Examples of glass that can be used for the transparent substrate include absorption-type glass (near-infrared absorbing glass) containing copper ions in fluorophosphate glass or phosphate glass, soda-lime glass, borosilicate glass, alkali-free glass, quartz glass, etc. Note that "phosphate glass" also includes silicophosphate glass, in which part of the glass skeleton is composed of _SiO2 .

The glass may be chemically strengthened glass obtained by ion exchange at a temperature below the glass transition point to replace alkali metal ions with small ionic radii (e.g., Li ions, Na ions) present on the main surface of the glass sheet with alkali ions with larger ionic radii (e.g., Na ions or K ions for Li ions, and K ions for Na ions).

Transparent resin materials that can be used as transparent substrates include polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyolefin resins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer, norbornene resin, acrylic resins such as polyacrylate and polymethyl methacrylate, urethane resin, vinyl chloride resin, fluororesin, polycarbonate resin, polyvinyl butyral resin, polyvinyl alcohol resin, and polyimide resin.

Crystal materials that can be used for the transparent substrate include birefringent crystals such as quartz, lithium niobate, and sapphire. The optical properties of the transparent substrate should be as described above for the optical filter obtained by laminating it with the absorption layer, reflective layer, etc. Sapphire is preferred as the crystal material.

Inorganic materials are preferred for the transparent substrate, with glass and sapphire being particularly preferred, from the standpoint of shape stability related to the long-term reliability of the optical properties and mechanical properties of the optical filter, and ease of handling during filter production.

The shape of the transparent substrate is not particularly limited and may be block, plate, or film. Its thickness is preferably, for example, 0.03 to 5 mm, and from the perspective of achieving a thinner substrate, more preferably 0.03 to 0.5 mm. From the perspective of processability, a transparent substrate made of glass and having a thickness of 0.05 to 0.5 mm is preferred.

(reflective layer)
The reflective layer is made of a dielectric multilayer film and has the function of blocking light in a specific wavelength range. Examples of reflective layers include those that transmit visible light and have wavelength selectivity that mainly reflects light of wavelengths other than the light-blocking range of the absorbing layer. The reflective layer preferably has a reflective region that reflects near-infrared light. In this case, the reflective region of the reflective layer may include the light-blocking region of the absorbing layer in the near-infrared range. The reflective layer is not limited to the above characteristics and may be appropriately designed to further block light in a specified wavelength range, for example, the near-ultraviolet range.

When the reflective layer has a reflective region that reflects near-infrared light, the reflective layer preferably specifically satisfies the following (iii-1):
(iii-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T _{RE850-1100ave0°} of light having a wavelength of 850 to 1100 nm is 0.2% or less.
The average transmittance T _{RE850-1100ave0°} is preferably 0.15% or less, and more preferably 0.05% or less.

When the reflective layer has a reflective region that reflects near-infrared light, it is preferable that the absorbing layer and the reflective layer have the following relationship:

In the case where the wavelength λ _ABSHT20-0° on the short wavelength side, at which the absorbing layer exhibits a transmittance of 20% for light with an incident angle of 0 degrees, satisfies 650 nm≦λ _ABSHT20-0° ≦800 nm, it is preferable that the relationship between the wavelength λ _ABSHT20-0° and the wavelength λ _RESHT20-0° on the short wavelength side, at which the reflective layer exhibits a transmittance of 20% in the wavelength region of 650 nm or more for light with an incident angle of 0 degrees, satisfies (iii-2).
(iii-2) λ _ABSHT20-0° +30nm≦λ _RESHT20-0° ≦790nm

It is preferable that the reflective layer further satisfies (iii-3).
(iii-3) The average transmittance for light in the wavelength region from λ _RESHT20-0° to λ _RESHT20-0° +300 nm is 10% or less.

The reflective layer is composed of a dielectric multilayer film in which low-refractive-index dielectric films (low-refractive-index films) and high-refractive-index dielectric films (high-refractive-index films) are alternately laminated. The high-refractive-index films preferably have a refractive index of 1.6 or more, more preferably 2.2 to 2.5. Examples of materials for the high-refractive-index films include Ta ₂ O ₅ , TiO ₂ , and Nb ₂ O ₅ . Of these, TiO ₂ is preferred from the standpoints of film formability, reproducibility in refractive index, etc., and stability.

On the other hand, the low refractive index film preferably has a refractive index of less than 1.6, more preferably 1.45 or more and less than 1.55. Examples of materials for the low refractive index film include _SiO2 and _SiOxNy . _SiO2 is preferred from the standpoints of reproducibility, stability, economy _, etc. in film formation.

Furthermore, it is preferable that the reflective layer exhibit a steep change in transmittance in the boundary wavelength region between the transmission and blocking regions. For this purpose, the total number of laminated layers in the dielectric multilayer film constituting the reflective layer is preferably 15 or more, more preferably 25 or more, and even more preferably 30 or more. However, as the total number of laminated layers increases, warping and an increase in film thickness may occur, so the total number of laminated layers is preferably 100 or less, more preferably 75 or less, and even more preferably 60 or less. Furthermore, the film thickness of the dielectric multilayer film is preferably 2 to 10 μm.

If the total number of layers and film thickness of the dielectric multilayer film are within the above ranges, the reflective layer will meet the requirements for miniaturization and suppress incidence angle dependency while maintaining high productivity. Furthermore, the dielectric multilayer film can be formed using, for example, vacuum film formation processes such as CVD, sputtering, and vacuum deposition, or wet film formation processes such as spraying and dipping.

The reflective layer may be a single layer (a group of dielectric multilayer films) that provides the desired optical characteristics, or two layers that provide the desired optical characteristics. When there are two or more reflective layers, each reflective layer may have the same or different configurations. When there are two or more reflective layers, they are usually composed of multiple reflective layers with different reflection bands.

For example, when two reflective layers are provided, one may be a near-infrared reflective layer that blocks light in the short wavelength band of the near-infrared region, and the other may be a near-infrared/near-ultraviolet reflective layer that blocks light in both the long wavelength band of the near-infrared region and the near-ultraviolet region. Also, for example, when the present filter has a transparent substrate and two or more reflective layers are provided, all may be provided on one major surface of the transparent substrate, or each reflective layer may be provided on both major surfaces of the transparent substrate, sandwiching the transparent substrate.

(Anti-reflection layer)
Examples of antireflection layers include dielectric multilayer films, intermediate refractive index media, and moth-eye structures in which the refractive index changes gradually. Among these, dielectric multilayer films are preferred from the viewpoints of optical efficiency and productivity. Antireflection layers are obtained by alternately laminating dielectric films, similar to reflective layers.

This filter may also include other components (layers) that provide absorption using inorganic fine particles that control the transmission and absorption of light in specific wavelength ranges. Specific examples of inorganic fine particles include ITO (indium tin oxide), ATO (antimony-doped tin oxide), cesium tungstate, and lanthanum boride. ITO fine particles and cesium tungstate fine particles have high transmittance for visible light and absorb light over a wide range of infrared wavelengths above 1200 nm, making them suitable for use in applications requiring blocking of such infrared light.

This filter has a reflective layer and an absorption layer containing an NIR dye (A) and a transparent resin (P), which allows it to maintain good transmittance of visible light, particularly green and red light, while providing excellent near-infrared light blocking, particularly long-wavelength near-infrared light blocking.

It is preferable that this filter satisfy all of the following requirements (3-1) to (3-3) regarding its optical characteristics measured at an incident angle of 0 degrees. It is even more preferable that this filter satisfy all of the following requirements (3-4) to (3-9) in addition to these.

(3-1) The minimum OD value in the wavelength region of the maximum absorption wavelength λ _max(A)TR of the NIR dye (A) ±10 nm is 4 or more. The minimum OD value at an incident angle of 0 degrees is more preferably 5 or more.

(3-2) The average transmittance T AVE490-560(0 _{° )} in the wavelength region of 490 to 560 nm is 82% or more, more preferably 83.0% or more, and even more preferably 83.5% or more.

(3-3) The average transmittance T AVE590-630 _{( 0°)} in the wavelength region of 590 to 630 nm is 50% or more, more preferably 55% or more, and even more preferably 60% or more.

(3-4) In the wavelength region of 600 to 800 nm, the absolute value of the difference between the wavelength λ _50%(0°) at which the transmittance is 50% at an incident angle of 0 degrees and the wavelength λ _50%(30°) at which the transmittance is 50% at an incident angle of 30 degrees, |λ _50%(30°) -λ _50%(0°) |, is 5 nm or less. |λ _50%(30°) -λ _50%(0°) | is more preferably 4 nm or less, and even more preferably 3 nm or less.

(3-5) The average transmittance T _{AVE490-560(30°)} in the wavelength region of 490 to 560 nm measured at an incident angle of 30 degrees is 80% or more. The average transmittance T _{AVE490-560(30°)} is more preferably 81% or more, and even more preferably 83% or more.

(3-6) The minimum OD value in the wavelength region of the maximum absorption wavelength λ _max(A)TR of the NIR dye (A) ±10 nm, measured at an incident angle of 30 degrees, is 3 or more. The minimum OD value at an incident angle of 30 degrees is more preferably 4 or more.

(3-7) In the wavelength region of 600 to 800 nm, the absolute value of the difference between the wavelength λ _50%(0°) at which the transmittance is 50% at an incident angle of 0 degrees and the wavelength λ _50%(50°) at which the transmittance is 50% at an incident angle of 50 degrees, |λ _50%(50°) -λ _50%(0°) |, is 15 nm or less. |λ _50%(50°) -λ _50%(0°) | is more preferably 13 nm or less, and even more preferably 10 nm or less.

(3-8) The average transmittance T _{AVE490-560(50°)} in the wavelength region of 490 to 560 nm measured at an incident angle of 50 degrees is 70% or more. The average transmittance T _{AVE490-560(50°)} is more preferably 72% or more, and even more preferably 74% or more.

(3-9) The minimum OD value in the wavelength region of the maximum absorption wavelength λ _max(A)TR of the NIR dye (A) ±10 nm, measured at an incident angle of 50 degrees, is 3 or more. The minimum OD value at an incident angle of 50 degrees is more preferably 4 or more.

This filter is useful as an optical filter for imaging devices, such as digital still cameras, in devices that have both imaging devices and optical components that use laser light. This filter is also useful for optical sensors, such as ambient light sensors.

An imaging device using this filter comprises a solid-state imaging element, an imaging lens, and this filter. This filter can be used, for example, by being placed between the imaging lens and the solid-state imaging element, or by being directly attached to the solid-state imaging element, imaging lens, etc. of the imaging device via an adhesive layer.

Next, the present invention will be explained in more detail using examples. First, a synthesis example and characteristics of the NIR dye (A) used in the absorption layer of the example will be described. Next, an example of an optical filter will be described.

[Test Examples 1 to 29: Synthesis and Evaluation of Dyes]
(Synthesis and evaluation of pigments)
NIR dye (A), NIR dye (B), and other NIR dyes were synthesized by the following methods. Synthesis Examples 1 to 11 are synthesis examples of NIR dye (A), Synthesis Examples 12 to 15 are synthesis examples of NIR dye (B), and Synthesis Examples 16 and 17 are synthesis examples of other NIR dyes. Furthermore, as the NIR dye (A), a commercially available product manufactured by Few Chemicals and shown in the following formula (S0772) was prepared, and as the other NIR dye, a commercially available product manufactured by Few Chemicals and shown in the following formula (S2437) was prepared, shown in the following formula (S2437):

The optical properties of these dyes were evaluated using an ultraviolet-visible-near-infrared spectrophotometer (UH4150, manufactured by Hitachi High-Tech Science Corporation), and the UH4150 was also used to evaluate the optical properties (spectral transmittance curves) below.

[Synthesis Example 1]
The dye (A1a-5Sb) was synthesized according to the reaction pathway shown below.

<Step 1>
Tris(4-nitrophenyl)amine (25 g, 66 mmol), palladium-activated carbon (palladium 10%) (6.5 g), 1,4-dioxane (350 mL), and methanol (300 mL) were added to a 1 L recovery flask and stirred. The mixture was cooled to 0°C and stirred. Ammonium formate (65 g, 990 mmol) was added and stirred at room temperature for 4 hours. After filtering the reaction mixture, the filtrate was extracted with dichloromethane, the solvent was removed, and the remaining solid was added with 300 mL of hexane and stirred for one day. The mixture was washed. After removing the hexane by filtration, 18.1 g (yield 95%) of intermediate 1 was obtained as a gray solid.

<Step 2>
Intermediate 1 (15 g, 52 mmol) obtained in Step 1, potassium carbonate (71.4 g, 520 mmol), 1-bromo-2-methylpropane (127 g, 930 mmol), and N,N-dimethylformamide (150 mL) were added to a 1 L recovery flask and stirred at 115°C for 24 hours. After returning to room temperature, a filtration operation was carried out and the mixture was washed with dichloromethane. The filtrate was extracted with dichloromethane, and after removing the solvent, the extract was washed with methanol, yielding 18.2 g (yield 56%) of intermediate 2 as a brown solid.

<Step 3>
Intermediate 2 (3 g, 4.8 mmol) obtained in step 2 and N,N-dimethylformamide (60 mL) were added to a 500 mL recovery flask and stirred at 60 °C until dissolved. Subsequently, a solution of silver hexafluoroantimonate(V) (3.79 g, 11 mmol) dissolved in N,N-dimethylformamide (30 mL) was added to the solution containing Intermediate 2 and stirred at 60 °C for 3 h. The precipitated solid was filtered, and the recovered solid was isolated by column chromatography (dichloromethane:methanol = 1000:30). After removing the solvent, the solid was dissolved in a small amount of dichloromethane and reprecipitated using ethyl acetate, yielding 2.8 g (yield 54%) of the dye (A1a-5Sb) as a green solid.

[Synthesis Example 2]
Intermediate 2 (3 g, 4.8 mmol) obtained in Step 2 of Synthesis Example 1 and ethyl acetate (50 mL) were added to a 500 mL recovery flask and stirred at 60 °C until dissolved. Subsequently, a solution of potassium bis(trifluoromethylsulfonyl)imide (3.8 g, 12 mmol) and ammonium peroxodisulfate (2.7 g, 12 mmol) dissolved in a mixed solvent of acetonitrile (30 mL) and water (30 mL) was added to the solution containing intermediate 2 and stirred at 60 °C for 4 h. After completion of the reaction, the mixture was returned to room temperature, water (100 mL) and hexane (200 mL) were added, and the solid was precipitated, filtered, and washed with ethyl acetate. The recovered solid was isolated by column chromatography (dichloromethane:methanol = 1000:30). After removing the solvent, the solid was dissolved in a small amount of dichloromethane and reprecipitated using ethyl acetate, yielding 3.6 g (yield 63%) of a green solid dye (A1a-5NS).

[Synthesis Example 3]
A green solid dye (A1a-5P) (2.6 g, yield 59%) was obtained in the same manner as in Synthesis Example 2, except that potassium bis(trifluoromethylsulfonyl)imide was replaced with potassium hexafluorophosphate (2.2 g, 12 mmol).

[Synthesis Example 4]
A green solid dye (A1a-5Cl) (2.5 g, yield 63%) was obtained in the same manner as in Synthesis Example 2, except that potassium bis(trifluoromethylsulfonyl)imide was changed to sodium perchlorate (1.5 g, 12 mmol).

[Synthesis Example 5]
A green solid dye (A1a-5B) (2.7 g, yield 71%) was obtained in the same manner as in Synthesis example 2, except that potassium bis(trifluoromethylsulfonyl)imide was changed to sodium tetrafluoroborate (1.3 g, 12 mmol).

[Synthesis Example 6]
The dye (A1a-4P) was synthesized according to the reaction pathway shown below.

<Step 1>
A reaction was carried out using the same starting materials as in Step 2 of Synthesis Example 1, except that 1-bromo-2-methylpropane was changed to 1-bromobutane (127 g, 930 mmol). The reaction product was extracted with dichloromethane and then isolated by column chromatography (hexane:ethyl acetate=1000:40) to obtain 23 g (yield 71%) of Intermediate 3 as a pale yellow oily substance.

<Step 2>
Intermediate 3 (3 g, 4.8 mmol) obtained in Step 1 of Synthesis Example 6 and ethyl acetate (50 mL) were added to a 500 mL recovery flask and stirred at 60 °C until dissolved. Subsequently, a solution of potassium hexafluorophosphate (2.2 g, 12 mmol) and ammonium peroxodisulfate (2.7 g, 12 mmol) dissolved in a mixed solvent of acetonitrile (30 mL) and water (30 mL) was added to the solution containing Intermediate 3 and stirred at 60 °C for 4 h. After completion of the reaction, the mixture was returned to room temperature, and water (100 mL) and hexane (200 mL) were added to precipitate a solid, which was then filtered and washed with ethyl acetate. The recovered solid was isolated by column chromatography (dichloromethane:ethyl acetate = 10:1). After removing the solvent, the solid was dissolved in a small amount of dichloromethane and reprecipitated using hexane to obtain 2.8 g (yield 63%) of a green solid dye (A1a-4P).

[Synthesis Example 7]
A method similar to that used in Step 2 of Synthesis example 6 was used, except that potassium hexafluorophosphate was changed to potassium bis(trifluoromethylsulfonyl)imide (3.8 g, 12 mmol), to obtain 3.1 g (yield: 54%) of a green solid dye (A1a-4NS).

[Synthesis Example 8]
0.9 g (yield 22%) of dye (A1a-4B) as a green solid was obtained in the same manner as in Step 2 of Synthesis example 6, except that potassium hexafluorophosphate was changed to sodium tetrafluoroborate (1.3 g, 12 mmol).

[Synthesis Example 9]
The dye (A1a-7P) was synthesized according to the method described below.

<Step 1>
A reaction was carried out using the same starting materials as in Step 2 of Synthesis Example 1, except that 1-bromo-2-methylpropane was replaced with 1-bromooctane (18 equivalents relative to Intermediate 1). The reaction product was extracted with dichloromethane and then isolated by column chromatography (hexane:ethyl acetate=1000:40), yielding 13.4 g (yield 67%) of Intermediate 4, a pale yellow oily substance.

<Step 2>
In the same manner as described in Step 2 of Synthesis Example 6, except that Intermediate 3 was changed to Intermediate 4, 1.0 g (yield 20%) of a green solid dye (A1a-7P) was obtained.

[Synthesis Example 10]
A green solid dye (A1a-7NS) (2.4 g, yield 37%) was obtained in the same manner as in Step 2 of Synthesis Example 9, except that the potassium hexafluorophosphate used in Step 2 was changed to potassium bis(trifluoromethylsulfonyl)imide.

[Synthesis Example 11]
The dye (A1a-1NS) was synthesized according to the method described below.

<Step 1>
A reaction was carried out using the same starting materials as in Step 2 of Synthesis Example 1, except that 1-bromo-2-methylpropane was replaced with bromoethane (18 equivalents relative to Intermediate 1). After extraction with dichloromethane, the product was isolated by column chromatography (hexane:ethyl acetate=8:2), yielding 1.7 g (yield 12%) of Intermediate 5, which was a pale yellow oily substance.

<Step 2>
In a similar manner to Synthesis Example 6, except that Intermediate 3 described in Step 2 was changed to Intermediate 5 and potassium hexafluorophosphate was changed to potassium bis(trifluoromethylsulfonyl)imide, 0.8 g (yield 22%) of a dye (A1a-1NS) was obtained as a green solid.

[Synthesis Example 12]
The dye (B1-5Sb) was synthesized according to the reaction pathway shown below.

<Step 1>
4-Bromoaniline (25.4 g, 148 mmol) and N,N-dimethylformamide (80 mL) were added to a 1 L recovery flask and stirred at 110°C until dissolved. Subsequently, 1-bromo-2-methylpropane (54.7 g, 399 mmol) and N-ethyldiisopropylamine (57.3 g, 444 mmol) were added, and the mixture was allowed to react at 130°C for 15 hours. After returning the mixture to room temperature, an extraction operation was carried out with a mixed solvent of ethyl acetate and hexane (1:4). After removing the solvent, the mixture was isolated by column chromatography (hexane:ethyl acetate=1000:50), yielding 15 g (yield 36%) of intermediate 6 as a white solid.

<Step 2>
Intermediate 6 (12 g, 42 mmol) obtained in Step 1, 1,4-phenylenediamine (1.1 g, 9.8 mmol), sodium tert-butoxide (8 g, 83 mmol), tris(dibenzylideneacetone)dipalladium(0) (1 g, 1.1 mmol), 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (2 g, 4 mmol), and 1,4-dioxane (80 mL) were added to a 1 L recovery flask and reacted at 100 °C for 20 h. After returning to room temperature and removing the remaining catalyst solid by filtration through Celite, extraction was performed with dichloromethane and saturated aqueous ammonium chloride solution. After removing the solvent, the precipitated solid was washed with methanol to obtain 17.5 g (97% yield) of intermediate 7 as a brown solid.

<Step 3>
Intermediate 7 (2 g, 2 mmol) obtained in step 2 and N,N-dimethylformamide (20 mL) were added to a 500 mL recovery flask and stirred at 60 °C until dissolved. Subsequently, a solution of silver hexafluoroantimonate(V) (1.6 g, 4.5 mmol) dissolved in N,N-dimethylformamide (20 mL) was added to the solution containing Intermediate 7 and stirred at 60 °C for 2 h. The precipitated solid was filtered and washed with N,N-dimethylformamide. Approximately 150 mL of water was slowly added dropwise to the filtrate. The precipitated solid was filtered again, washed with water and hexane, and isolated by column chromatography (dichloromethane:ethyl acetate = 7:3). After removing the solvent, the solid was dissolved in a small amount of dichloromethane and reprecipitated using ethyl acetate, yielding 1.3 g (43% yield) of the dye (B1-5Sb) as a reddish-brown solid.

[Synthesis Example 13]
Intermediate 7 (5 g, 5.4 mmol) obtained in Step 2 of Synthesis Example 12 and ethyl acetate (50 mL) were added to a 500 mL recovery flask and stirred at 60 °C until dissolved. Subsequently, a solution of potassium bis(trifluoromethylsulfonyl)imide (4.4 g, 13.8 mmol) and ammonium peroxodisulfate (3.1 g, 13.5 mmol) dissolved in a mixed solvent of acetonitrile (30 mL) and water (30 mL) was added to the solution containing intermediate 7 and stirred at 60 °C for 4 h. After completion of the reaction, the mixture was returned to room temperature, water (100 mL) and hexane (200 mL) were added, and the solid was precipitated, filtered, and washed with ethyl acetate. The recovered solid was isolated by column chromatography (dichloromethane:methanol = 1000:30). After removing the solvent, the solid was dissolved in a small amount of dichloromethane and reprecipitated using hexane to obtain 6.0 g (yield 75%) of a reddish-brown solid dye (B1-5NS).

[Synthesis Example 14]
A reddish-brown solid dye (B1-5P) was obtained in a yield of 36% in the same manner as in Synthesis Example 2, except that potassium bis(trifluoromethylsulfonyl)imide was replaced with potassium hexafluorophosphate.

[Synthesis Example 15]
An n-butyl-modified intermediate was synthesized (yield 89%) in the same manner as in Step 1 of Synthesis Example 12, except that 1-bromo-2-methylpropane used in Step 1 was changed to 1-bromobutane (54.7 g, 399 mmol). Using the same methods as in Steps 2 and 3 of Synthesis Example 12, a reddish-brown solid dye (B1-4Sb) was obtained in a yield of 72%.

[Synthesis Example 16]
Dye (S1) was synthesized according to the reaction pathway shown below. Specifically, product (10) (6.5 mmol), prepared with reference to European Journal of Medicinal Chemistry, 54, 647, (2012), and squaric acid (3.4 mmol) were placed in a 500 mL recovery flask, dissolved in toluene (330 mL) and 1-butanol (110 mL), and quinoline (8 mmol) was added. The mixture was stirred at 150°C for 4 hours. Product _{( 10} ) is the iodide salt of a compound in which the hydrogen at position 1 of 2-methyl-benzo[c,d]indole is substituted with R, where R is _-CH2 -CH( _C6H13 )( _C8H17 ).

After the reaction was complete, the solvent was removed, and the product was isolated by column chromatography (hexane:ethyl acetate = 8:2). After the solvent was removed and the product was washed with hexane, a reddish-brown solid, dye (S1) (0.5 g, yield 25%), was obtained.

[Synthesis Example 16]
Dye (S2) was synthesized according to the reaction pathway shown below.

<Step 1>
A 1-L three-neck flask was charged with benzo[cd]indol-2(1H)-one (30 g, 177 mmol) and chloroform (500 mL), and the mixture was heated and stirred at 65°C to dissolve the raw materials. The mixture was then cooled to 0°C, and bromine (28.3 g, 177 mmol) was slowly added dropwise. After the addition was complete, the mixture was returned to room temperature and stirred for 24 hours. Hexane was then added to the reaction mixture to dilute it, and the precipitate was collected by filtration. The solid on the filter paper was washed multiple times with hexane and dried in vacuo, yielding 60 g (yield of over 100%) of intermediate 8, an ochre solid.

<Step 2>
Intermediate 8 (30 g, 121 mmol) synthesized in Step 1, 4-dimethylaminopyridine (2.0 g, 16 mmol), potassium iodide (4.0 g, 24 mmol), and sulfolane (300 mL) were added to a 1 L recovery flask and stirred at 70 °C for 1 h. Potassium hydroxide (21 g, 374 mmol) and 7-(bromomethyl)pentadecane (111 g, 363 mmol) were added to the reaction solution, and the reaction was allowed to proceed at 70 °C for 19 h. After completion of the reaction, the mixture was returned to room temperature, and extraction was performed using an organic solvent mixture of hexane and ethyl acetate (4:1) and water, followed by solvent removal. The product was then isolated by column chromatography (hexane:ethyl acetate = 1000:10), yielding 45 g (78% yield) of intermediate 9, a yellow oily substance.

<Step 3>
Intermediate 9 (33 g, 70 mmol) synthesized in Step 2, ethyl acetate (2.5 g, 28 mmol), copper(I) iodide (1.9 g, 10 mmol), and 28% sodium methoxide/methanol solution (42 g) were added to a 1 L eggplant flask and stirred at 90 °C for 6 h. Copper(I) iodide (1 g, 5 mmol) and 28% sodium methoxide/methanol solution (20 g) were then added and stirred at 90 °C for an additional 15 h. After the reaction was complete, the mixture was returned to room temperature, filtered through Celite, and extracted with dichloromethane and water to remove the solvent. The mixture was then isolated by column chromatography (hexane:ethyl acetate = 1000:30) to obtain 26 g (88% yield) of intermediate 10, a yellow oily substance.

<Step 4>
Intermediate 10 (26 g, 61 mmol) synthesized in Step 3 and dichloromethane (500 mL) were placed in a 2 L three-neck flask and cooled to -78 °C. Then, 1 M boron tribromide dichloromethane solution (200 mL) was slowly added dropwise. After the addition was complete, the reaction solution was returned to room temperature and stirred for 2 h. After the reaction was complete, the mixture was cooled to 0 °C, and 200 mL of water was slowly added to quench the boron tribromide. The precipitated solid was filtered, and the filtrate was extracted with dichloromethane and aqueous sodium bicarbonate solution to remove the solvent. This was combined with the solid recovered during filtration and washed multiple times with hexane to obtain 24 g (95% yield) of intermediate 11 as a yellow solid.

<Step 5>
Intermediate 11 (10 g, 24 mmol) synthesized in Step 4, potassium carbonate (16.9 g, 120 mmol), and DMF (120 mL) were added to a 1 L three-neck flask and stirred at 70°C. Then, 7-(bromomethyl)pentadecane (8.95 g, 29 mmol) was added dropwise, and the mixture was stirred at 70°C for 2 hours. After completion of the reaction, extraction was performed with an organic solvent mixture of hexane and ethyl acetate in a ratio of 1:1 and water, and the solvent was removed. The product was then isolated by column chromatography (hexane:ethyl acetate=10:1), yielding 14 g (yield 91%) of intermediate 12, a yellow oily substance.

<Step 6>
Intermediate 12 (14 g, 22 mmol) synthesized in Step 5, epichlorohydrin (8.2 g, 88 mmol), chloroform (50 mL), and diethyl ether (20 mL) were added to a 1-L three-neck flask and stirred at 70 °C. A mixed solution of boron trifluoride-ethyl ether complex (15.9 g, 110 mmol) and chloroform (30 mL) was added dropwise, and the mixture was heated to 130 °C and stirred for 15 hours. The reaction solution was then cooled, toluene was added, and the solvent was removed twice using an evaporator to obtain an orange-brown oily substance (Intermediate 13'). Ethanol (20 mL) and Meldrum's acid (4.6 g, 32 mmol) were added to the oily substance, followed by triethylamine (11.4 g, 110 mmol), and the mixture was stirred at room temperature for 5 hours. After the reaction was completed, toluene was added, and the solvent was removed twice using an evaporator. The residue was then isolated by column chromatography (hexane:ethyl acetate=6:4) to obtain 8 g (yield 47%) of Intermediate 13, a magenta oily substance.

<Step 7>
Intermediate 13 (8 g, 10 mmol) synthesized in Step 6 and hydrochloric acid (15 mL) were added to a 1 L recovery flask and heated at 130°C for 1 hour. Tetrafluoroboric acid (3 mL) was then added and the reaction was continued for another 1 hour. After the reaction was completed, the mixture was returned to room temperature, 50 mL of water was added, and 20 mL of tetrafluoroboric acid was added. After that, an extraction operation was performed using dichloromethane and water, and the solvent was removed, yielding 7.1 g (yield 94%) of intermediate 14, an orange oily substance.

<Step 8>
Intermediate 14 (7.1 g, 10 mmol) synthesized in Step 7, squaric acid (0.59 g, 5.2 mmol), toluene (500 mL), 1-butanol (170 mL), and quinoline (1.77 g) were added to a 1 L recovery flask and reacted for 2 hours at 130°C. The solvent was then removed using an evaporator, and the residue was isolated by column chromatography (hexane:ethyl acetate=9:1), yielding 3.4 g (yield 55%) of dye (S2) as a black solid.

Dye-containing resin layers were produced using the various dyes and transparent resins prepared above, and their optical properties were measured. Additionally, various dyes were dissolved in dichloromethane, and their optical properties were measured and compared with those of the dye-containing resin layer. The following commercially available transparent resins were used. The results are shown in Table 14.

(Transparent resin (P))
Resin A: Neoprim (registered trademark) C-3G30 (trade name, manufactured by Mitsubishi Gas Chemical Company, Inc.), varnish containing polyimide resin, Tg of the contained polyimide resin: 320°C
Resin B: ARTON (registered trademark) F4520 (trade name, manufactured by JSR Corporation), cycloolefin resin, Tg: 151°C
Resin C: B-OKP-2 (trade name, manufactured by Osaka Gas Chemicals Co., Ltd.), polyester resin, Tg: 150°C
Resin D: OKP-850 (trade name, manufactured by Osaka Gas Chemicals Co., Ltd.), polyester resin, Tg: 151°C
Resin E: Panlite (registered trademark) SP3810 (trade name, manufactured by Teijin Limited), polycarbonate resin, Tg: 150°C
(Other transparent resins)
Resin F: BR50 (trade name, manufactured by Mitsubishi Rayon Co., Ltd.), acrylic resin, Tg: 100°C

The dye prepared above was uniformly dissolved in a transparent resin dissolved in cyclohexanone at a concentration of 10% by mass relative to the solids concentration of the transparent resin. The resulting solution was applied to a glass plate (D263: trade name, manufactured by SCHOTT) and dried to obtain a dye-containing resin layer with a thickness of approximately 1 μm. The spectral transmittance curve of the dye-containing resin layer was obtained using the spectral transmittance curve of the glass plate with the dye-containing resin layer and the spectral transmittance curve of the glass plate.

The internal transmittance spectrum of the prepared dye-containing resin layer was measured in the wavelength range of 350 to 1200 nm using an ultraviolet-visible-near-infrared spectrophotometer, and calculated using the internal transmittance T [%] (= measured transmittance [%] / (100 - measured reflectance [%]) × 100 [%]). The amount of dye added (dye concentration) shown in the table is the mass parts per 100 mass parts of transparent resin when adjusted so that the internal transmittance of light at the maximum absorption wavelength λ _maxTR is 10% at a film thickness of 2 μm.

From the spectral transmittance curve adjusted so that the light transmittance at the maximum absorption wavelength λ _maxTR was 10%, the average internal transmittance T _AVE435-480TR for light with wavelengths of 435 to 480 nm, the average internal transmittance T _AVE490-560TR for light with wavelengths of 490 to 560 nm, and the average internal transmittance T _AVE590-630TR for light with wavelengths of 590 to 630 nm were determined. When there are two wavelengths in the wavelength range of 650 to 1150 nm at which the internal transmittance is 50%, the width W _T50% between the two wavelengths was determined. In the table, the wavelength on the short wavelength side at which the internal transmittance is 50% in the wavelength range of 650 to 1150 nm is shown as λ _SH50% and the wavelength on the long wavelength side is shown as λ _LG50% .

The dye was dissolved in dichloromethane and the optical absorption spectrum at a wavelength of 350 to 1200 nm was measured, and the maximum absorption wavelength λ _maxDCM was determined from the spectral transmittance curve. Furthermore, the dye concentration in dichloromethane was adjusted so that the light transmittance at the maximum absorption wavelength λ _maxDCM was 10% from the spectral transmittance curve, and the average transmittance T _{AVE435-480DCM} of light with a wavelength of 435 to 480 nm, the average transmittance T _{AVE490-560DCM} of light with a wavelength of 490 to 560 nm, and the average transmittance T _{AVE590-630DCM} of light with a wavelength of 590 to 630 nm was calculated, and the difference from the average internal transmittance of the dye-containing resin layer was calculated. In the table, T _{AVE435-480DCM} - T _AVE435-480TR is shown in the "Difference between T _AVE435-480 " column. Similarly, the column "Difference between T _{AVE490 and} T AVE560" shows T _{AVE490-560DCM} - T _AVE490-560TR , and the column "Difference between T _AVE590 and T _{AVE590-630DCM} - T _AVE590-630TR ."

7 shows the spectral transmittance curves of the dye (A1a-5NS) in a transparent resin (P; resin A) and in dichloromethane in Test Example 2. Furthermore, FIG. 8 shows the spectral transmittance curves of the dye (A1a-5NS) in a transparent resin (resin F) and in dichloromethane in Test Example 19. In FIGS. 7 and 9, the spectral transmittance curves of the dye measured in the transparent resin are indicated by double-headed arrows to indicate the range of W _T50% .

From Table 14, it can be seen that the combinations of NIR dye (A) and transparent resin (P) in Test Examples 1 to 18 have the characteristics (1-1) to (1-6). It can be seen that tris-type immonium dyes are preferred for the NIR dye (A) in terms of the wide range of near-infrared light absorption shown at _WT50% . Furthermore, it can be seen that for the NIR dye (A), in terms of the small difference in optical properties between the dichloromethane solution and the resin, Xa ^- is preferably N[SO ₂ CF ₃ ] ₂ ^- , SbF ₆ ^- , or PF ₆ ^- , and N[SO ₂ CF ₃ ] ₂ ^- is particularly preferred. It can be seen that polyimide resins are preferred as the transparent resin (P) in terms of the high visible light transmittance.

In Test Examples 19 to 23, either the NIR dye or the transparent resin did not meet the requirements for an NIR dye (A) or a transparent resin (P), and therefore did not meet one or more of the characteristics (1-1) to (1-6). Test Examples 24 to 28 are examples in which a dye (B1) was combined with a transparent resin (P) or a transparent resin that does not meet the requirements for a transparent resin (P), and it was found that the dye (B1) functions favorably as an NIR dye (B) when combined with a transparent resin (P) such as a polyimide resin.

[Examples 1 to 11: Production and evaluation of optical filters]
(Manufacturing of optical filters)
Optical filters having the same configuration as the optical filter 10B shown in Figure 2 were manufactured and evaluated by the following method. The configurations of the optical filters and the evaluation results are shown in Table 15. Examples 1 to 7 are working examples, and Examples 8 to 11 are comparative examples.

In each example, a CuO-containing fluorophosphate glass substrate (manufactured by AGC Inc., thickness 0.2 mm) or a 0.08 mm thick Teijin PureAce WRM5-80 resin substrate (manufactured by Teijin Limited, trade name, polycarbonate resin, Tg 215°C) was used as the transparent substrate. In the table, these are referred to as "absorbing glass" and "PC resin," respectively.

The reflective layer used was a dielectric multilayer film formed as follows. The dielectric multilayer film was formed by laminating a total of 42 alternating layers of _TiO2 and _SiO2 films by vapor deposition on one main surface of a transparent substrate. The configuration of the reflective layer was simulated using the number of layers in the dielectric multilayer film, the thickness of the _TiO2 film, and the thickness of the _SiO2 film as parameters, and was designed to have an average transmittance of 0.03% for light with wavelengths of 850 to 1100 nm on the spectral transmittance curve at an incident angle of 0 degrees.

Furthermore, on the main surface of the transparent substrate opposite to the surface on which the reflective layer was formed, an absorbing layer having a thickness of approximately 2.0 μm was formed by combining the transparent resin shown in the table with NIR dye (A), NIR dye (B), NIR dye (C) (dye (I-12-23)), and other NIR dyes. Here, for dye (I-12-23), the maximum absorption wavelength λ _max(C)TR in the spectral transmittance curve for wavelengths of 350 to 1200 nm measured after being incorporated into resin A was 714 nm.
The content of the dye in the table is the parts by mass of the dye relative to 100 parts by mass of the transparent resin.

The following dyes (15), (16), and (17) were used as other NIR dyes. Here, dye (15) is a dye that, when incorporated into resin A and measured, has a maximum absorption wavelength λ _max(A)TR of 937 nm in the spectral transmittance curve for wavelengths of 350 to 1200 nm, but does not satisfy the characteristic (1-4). For dyes (16) and (17), when incorporated into resin F and measured, the maximum absorption wavelengths λ _maxTR are 839 nm and 771 nm, respectively.

[Synthesis of dye (15)]
Dye (15) was synthesized according to the reaction scheme shown below.

<Step b1>
2-Bromothiophene (9.00 g, 55.2 mmol) and magnesium (4.03 g, 165 mmol) were placed in a flask and dissolved in anhydrous tetrahydrofuran (55 mL) under a nitrogen atmosphere. The mixed solution was stirred at 80°C for 1 hour. [1,3-bis(diphenylphosphino)propane]nickel(II) dichloride (1.20 g, 2.21 mmol) and 2,3-dibromothiophene (12.7 g, 52.5 mmol) were placed in a separate flask and dissolved in anhydrous diethyl ether (110 mL). The diethyl ether mixed solution was cooled to 0°C, and the tetrahydrofuran mixed solution was added dropwise, followed by stirring at room temperature for 3 hours. After completion of the reaction, water (55 mL) was added to the mixed solution, followed by extraction with ethyl acetate. The organic layer was washed with saturated brine, the solvent was removed, and intermediate A3-11 (8.93 g, yield 66%) was obtained by column chromatography (hexane).

<Step b2>
Intermediate A3-11 (8.09 g, 33 mmol) obtained in step b1 was placed in a flask and dissolved in anhydrous diethyl ether (230 mL) under a nitrogen atmosphere. The solution was cooled to -78°C, and a 1.6 M solution of n-butyllithium in hexane (20 mL, 32.0 mmol) was added dropwise, followed by stirring for 1 hour. Subsequently, a solution of benzophenone (6.56 g, 36.0 mmol) in anhydrous diethyl ether (120 mL) was added dropwise. The mixture was stirred at room temperature for 24 hours. After completion of the reaction, saturated aqueous ammonium chloride solution (200 mL) was added, followed by extraction with diisopropyl ether. The resulting organic layer was washed with saturated brine, the solvent was removed, and intermediate A3-12 (8.81 g, yield 77%) was obtained by column chromatography (hexane:dichloromethane = 1:1).

<Step b3>
Intermediate A3-12 (4.94 g, 14.4 mmol) obtained in step b2 and Amberlyst 15 (2.30 g) were placed in a flask and dissolved in anhydrous toluene (300 mL) under a nitrogen atmosphere. The mixture was refluxed and stirred for 7 hours. After the reaction was completed, the filtrate was filtered, the solvent was removed, and intermediate A3-13 (4.29 g, 91%) was obtained by column chromatography (hexane:dichloromethane = 2:1).

<Step b4>
Intermediate A3-13 (4.00 g, 12.1 mmol) obtained in step b3 was placed in a flask and dissolved in anhydrous dimethylformamide (120 mL) under a nitrogen atmosphere. To the solution, an anhydrous dimethylformamide solution (30 mL) of N-bromosuccinimide (2.16 g, 12.1 mmol) was added dropwise. The mixture was stirred at room temperature for one day. After the reaction was completed, the mixture was poured into ice water and extracted with diisopropyl ether. The resulting organic layer was washed with saturated brine, the solvent was removed, and intermediate A3-14 (3.67 g, yield 74%) was obtained by column chromatography (dichloromethane).

<Step b5>
Intermediate A3-14 (3.50 g, 8.55 mmol) obtained in step b4 and magnesium turnings (0.416 g, 17.1 mmol) were placed in a flask and dissolved in anhydrous tetrahydrofuran (20 ml) under a nitrogen atmosphere. The solution was refluxed for 3 hours and cooled to -40°C. In a separate flask, N-chlorosuccinimide (1.03 g, 7.70 mmol) was dissolved in anhydrous toluene (20 ml) under a nitrogen atmosphere, and bis-(2-ethylhexyl)amine (1.86 g, 7.70 mmol) was added and stirred for 20 minutes.

Tetraisopropyl orthotitanate (2.43 g, 8.55 mmol) was added dropwise to the mixed solution cooled to -40°C and stirred for 5 minutes, followed by the dropwise addition of a mixed solution of N-chlorosuccinimide and bis-(2-ethylhexyl)amine. The mixture was stirred at room temperature for 3 hours, and after the reaction was complete, saturated aqueous potassium carbonate solution (17 ml) was added. The mixture was then diluted with ethyl acetate and filtered, and the resulting solution was extracted with ethyl acetate. The resulting organic layer was washed with saturated brine, the solvent was removed, and intermediate A3-15 (1.34 g, yield 27.5%) was obtained by column chromatography (hexane:triethylamine=100:3).

<Step b6>
Intermediate A3-15 (1.30 g, 2.28 mmol) obtained in step b5 and 3,4-dihydroxy-3-cyclobutene-1,2-dione (0.130 g, 1.14 mmol) were placed in a flask and dissolved in a mixed solution of normal butanol (6 ml) and toluene (6 ml) under a nitrogen atmosphere. The mixture was refluxed and stirred for 3 hours, and after the reaction was completed, the solvent was removed and dye (15) (0.445 g, yield 32%) was obtained by column chromatography (dichloromethane:methanol:triethylamine=100:1:3).

[Synthesis of dye (16) and dye (17)]
Dyes (16) and (17) were synthesized according to the method described in J. Heterocyclic. Chem., 42, 959, (2005).

(evaluation)
<Optical properties of absorption layer>
Spectral transmittance curves at an incident angle of 0 degree were obtained for the absorption layers of the obtained optical filters of Examples 1 to 11. When the average OD value in the wavelength region of the maximum absorption wavelength λ _max(A)TR ±10 nm of the NIR dye (A) in the spectral transmittance curves was set to 1, the average internal transmittance T _{AVE435-480(AL)} in the wavelength region of 435 to 480 nm, the average internal transmittance T _{AVE490-560(AL)} in the wavelength region of 490 to 560 nm, and the average internal transmittance T _{AVE590-630(AL)} in the wavelength region of 590 to 630 nm were determined.

Furthermore, when the average OD value in the wavelength region of the maximum absorption wavelength λ _max(A)TR ±10 nm of the NIR dye (A) was set to 1, the wavelength λ _50% at which the internal transmittance was 50% in the wavelength region of 600 to 800 nm and the sum of the width of the wavelength region at which the internal transmittance was 30% or less in the wavelength region of 600 to 1200 nm ("Width of T _30% or less" in the table) were calculated. The table also shows the transmittance T ₅₀₀ at a wavelength of 500 nm and the transmittance T ₆₀₀ at a wavelength of 600 nm.

<Optical characteristics of optical filters>
Furthermore, the spectral transmittance curves of the obtained optical filters of Examples 1 to 11 were obtained at angles of incidence of 0 degrees, 30 degrees, and 50 degrees, and the following optical properties were determined.

The minimum OD value in the wavelength region of the maximum absorption wavelength λ _max(A)TR ±10 nm of the NIR dye (A) at an incident angle of 0 degrees, the average transmittance T _{AVE435-480(0°)} in the wavelength region of 435 to 480 nm, the average transmittance T _{AVE490-560(0°)} in the wavelength region of 490 to 560 nm, the average transmittance T _{AVE590-630(0°)} in the wavelength region of 590 to 630 nm, and the wavelength λ _50%(0°) at which the transmittance becomes 50% in the wavelength region of 600 to 800 nm were determined.

The minimum OD value in the wavelength region of the maximum absorption wavelength λ _max(A)TR of the NIR dye (A) at an incident angle of 30 degrees ±10 nm, the absolute value of the difference |λ _{50%(30°) −λ 50%(0°)} | between the wavelength λ 50%(0°) at which the transmittance is 50% at an incident angle of 0 degrees and the wavelength λ _50%(30°) at which the transmittance is _{50 % at an incident angle of 30 degrees} in the wavelength region of 600 to 800 nm, and the average transmittance T _{AVE490-560(30°)} in the wavelength region of 490 to 560 nm were determined.

The minimum OD value in the wavelength region of the maximum absorption wavelength λ _max(A)TR of the NIR dye (A) at an incident angle of 50 degrees ±10 nm, the absolute value of the difference |λ _{50%(50°) −λ 50%(0°)} | between the wavelength λ 50%(0°) at which the transmittance is 50% at an incident angle of 0 degrees and the wavelength λ _50%(50°) at which the transmittance is _{50 %} at an incident angle of 50 degrees in the wavelength region of 600 to 800 nm, and the average transmittance T _{AVE490-560(50°)} in the wavelength region of 490 to 560 nm were determined.

9 and 10 show the spectral transmittance curves of the absorption layer and optical filter in the optical filters of Example 1, FIG. 11 and FIG. 12 show the spectral transmittance curves of Example 4, and FIG. 13 and FIG. 14 show the spectral transmittance curves of Example 6. FIGS. 15 and 16 show the spectral transmittance curves of the absorption layer and optical filter in the optical filter of Comparative Example 8. In the spectral transmittance curves of the absorption layer in each example, the "width of _30% or less of T" is indicated by W or Wa and Wb. In Examples 4, 6, and 8, the "width of _30% or less of T" is the sum of Wa and Wb.

Table 15 and Figures 10, 12, and 14 show that the optical filters of Examples 1 to 7 maintain sufficiently high transmittance for visible light, particularly for green and red light, and also have excellent near-infrared light blocking properties, particularly for long-wavelength near-infrared light.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2019-114575) filed on June 20, 2019, the contents of which are incorporated herein by reference.

The optical filter of the present invention maintains sufficiently high transmittance for visible light, particularly for green and red light, and also exhibits excellent near-infrared light blocking properties, particularly long-wavelength near-infrared light blocking properties. According to the present invention, an imaging device and optical sensor that use this optical filter can be provided that have excellent color reproducibility and durability.

10A, 10B, 10C, 10D, 10E, 10F...optical filters, 11, 11a, 11b...absorption layers, 12, 12a, 12b...reflective layers, 13...transparent substrate, 14...anti-reflection layer.

Claims (14)

An optical filter comprising an absorption layer containing a transparent resin, a near-infrared absorbing dye (A) having a maximum absorption wavelength in a wavelength region of 850 to 1100 nm , and a near-infrared absorbing dye (C) having a maximum absorption wavelength in a wavelength region of 630 to 750 nm , and a dielectric multilayer film,
An optical filter that satisfies all of the following requirements (3-2) to (3-8).
(3-2) In the optical properties measured at an incident angle of 0 degrees, the average transmittance T _{AVE490-560 (0°)} in the wavelength range of 490 to 560 nm is 82% or more.
(3-3) In the optical properties measured at an incident angle of 0 degrees, the average transmittance T _{AVE590-630 (0°)} in the wavelength range of 590 to 630 nm is 50% or more.
(3-4) In the wavelength region of 600 to 800 nm, the absolute value of the difference between the wavelength λ _{50% (0°)} at which the transmittance is 50% at an incident angle of 0 degrees and the wavelength λ _{50% (30°)} at which the transmittance is 50% at an incident angle of 30 degrees, |λ _{50% (30°)} −λ _{50% (0°)} |, is 5 nm or less.
(3-5) The average transmittance T _{AVE490-560(30°)} in the wavelength region of 490 to 560 nm measured at an incident angle of 30 degrees is 80% or more.
(3-6) The minimum OD value in the wavelength region of the maximum absorption wavelength λ _max(A)TR of the near-infrared absorbing dye (A) ±10 nm, measured at an incident angle of 30 degrees, is 3 or more.
(3-7) In the wavelength region of 600 to 800 nm, the absolute value of the difference between the wavelength λ _50%(0°) at which the transmittance is 50% at an incident angle of 0 degrees and the wavelength λ _50%(50°) at which the transmittance is 50% at an incident angle of 50 degrees, |λ _50%(50°) −λ _50%(0°) |, is 15 nm or less.
(3-8) The average transmittance T _{AVE490-560(50°)} in the wavelength region of 490 to 560 nm measured at an incident angle of 50 degrees is 70% or more. 2. The optical filter according to claim 1, wherein the optical characteristics measured at an incident angle of 0 degrees satisfy the following requirement (3-1):
(3-1) The near-infrared absorbing dye (A) has a minimum OD value of 4 or more in a wavelength region of the maximum absorption wavelength λ _max(A)TR ±10 nm. The optical filter according to claim 1 or 2, further satisfying the following requirement (3-9):
(3-9) The minimum OD value in the wavelength region of the maximum absorption wavelength λ _max(A)TR of the near-infrared absorbing dye (A) ±10 nm, measured at an incident angle of 50 degrees, is 3 or more. An optical filter according to any one of claims 1 to 3, wherein, in requirement (3-4), the absolute value |λ50%(30°)-λ50%(0°)| is 4 nm or less. 5. The optical filter according to claim 1, wherein in the requirement (3-7), the absolute value |λ _50%(50°) −λ _50%(0°) | is 10 nm or less. 6. The optical filter according to claim 1, wherein the absorption layer satisfies the following (2-1) and (2-2):
(2-1) The average internal transmittance T _{AVE490-560(AL)} in the wavelength region of 490 to 560 nm is 88% or more.
(2-2) The average internal transmittance T _{AVE590-630(AL)} in the wavelength region of 590 to 630 nm is 70% or more. 7. The optical filter according to claim 6, wherein the absorption layer satisfies the following (2-3):
(2-3) It has a wavelength λ _50% in the wavelength region of 600 to 700 nm, at which the internal transmittance is 50%. 7. The optical filter according to claim 6, wherein the absorption layer satisfies the following (2-4):
(2-4) The total width of the wavelength range in which the internal transmittance is 30% or less in the wavelength range of 600 to 1200 nm is 250 nm or more. The optical filter described in any one of claims 1 to 8, wherein the transparent resin is a polyimide resin. The optical filter according to any one of claims 1 to 9, further comprising a transparent substrate, the absorption layer and the dielectric multilayer film being respectively provided on the main surface of the transparent substrate. The optical filter according to claim 10 , wherein the transparent substrate is made of a transparent resin material or glass. The optical filter described in claim 11, wherein the glass is a fluorophosphate-based glass doped with copper ions or a phosphate-based glass doped with copper ions. An imaging device equipped with the optical filter according to any one of claims 1 to 12. An optical sensor equipped with the optical filter according to any one of claims 1 to 12.