JP7552271B2 - Optical Filters - 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.

In imaging devices using solid-state imaging elements, optical filters are used that transmit light in the visible range (hereafter also referred to as "visible light") and block light in the ultraviolet wavelength range (hereafter also referred to as "ultraviolet light") and near-infrared wavelength range (hereafter also referred to as "near-infrared light") in order to reproduce color tones well and obtain clear images.

Such optical filters can be made in a variety of ways, including reflective filters in which thin dielectric films with different refractive indices are alternately stacked (dielectric multilayer film) on one or both sides of a transparent substrate, and the interference of light is used to reflect the light to be blocked.

Optical filters with dielectric multilayer film have problems such as changes in the spectral transmittance curve depending on the angle of incidence because the optical thickness of the dielectric multilayer film changes depending on the angle of incidence, light leakage due to high transmittance of near-infrared light that should have high reflectance at high angles of incidence, and noise caused by near-infrared light reflected by the dielectric multilayer film. When such filters are used, the spectral sensitivity of the solid-state imaging element may be affected by the angle of incidence. In particular, with the recent trend toward lower height camera modules, use under high angle of incidence conditions is expected.

In addition, in dielectric multilayer films, drastic changes in transmittance (ripples) can occur due to interference caused by reflected light at the interfaces of each layer depending on the number of layers stacked in the multilayer film. The larger the angle of incidence, the greater the ripples that occur. Dielectric multilayer films used in optical filters that transmit light in the visible wavelength range and block light in the near-infrared wavelength range are designed to transmit visible light and block light with long wavelengths beyond near-infrared light. Conventional dielectric multilayer films are designed to suppress light leakage in the near-infrared range, but ripples occur in the visible light range, and the incident angle that is considered is only up to about 30 degrees.

Patent Document 1 describes a near-infrared cut filter that includes a dielectric multilayer film and suppresses ripples in the visible light region at high angles of incidence.
Patent Document 2 describes an optical filter that reduces the incidence angle dependency by combining various near-infrared absorbing dyes without providing a dielectric multilayer film.

JP 2019-120942 A JP 2019-32371 A

However, the near-infrared cut filter described in Patent Document 1 has a change in spectral transmittance curve at a high incident angle, and the blocking ability in the near-infrared light region changes.
The optical filter described in Patent Document 2 has low transmittance in the visible light region because visible light is also absorbed by the dye used in a large amount to ensure the shielding ability in the near-infrared light region and the incidence angle dependency.

The present invention aims to provide an optical filter that has high transmittance for visible light and high shielding properties for near-infrared light, suppresses ripples even at high angles of incidence, and suppresses changes in shielding properties at high angles of incidence for near-infrared light.

The present invention provides an optical filter having the following configuration.
[1] An optical filter comprising a substrate and a dielectric multilayer film laminated as an outermost layer on at least one main surface side of the substrate,
the substrate has a resin film containing a dye (IR) and a resin;
The dye (IR) has a maximum absorption wavelength in dichloromethane at 680 to 1000 nm,
The optical filter satisfies all of the following optical properties (i-1) to (i-10).
(i-1) At a wavelength of 450 to 500 nm, the average reflectance R _{450-500 (5 deg) AVE} at an incident angle of 5 degrees is 3% or less, and the average reflectance R _{450-500 (40 deg) AVE} at an incident angle of 40 degrees is 5% or less. (i-2) At a wavelength of 500 to 580 nm, the average reflectance R _{500-580 (5 deg) AVE} at an incident angle of 5 degrees is 2.5% or less, and the average reflectance R _{500-580 (40 deg) AVE} at an incident angle of 40 degrees is 4% or less. (i-3) The R _{450-500 (5 deg) AVE} > the R _{500-580 (5 deg) AVE} and the R _{450-500 (40 deg) AVE} > the R (i-4) At a wavelength of 450 to 580 nm, the maximum reflectance R _{450-580 (5 deg) MAX} at an incident angle of 5 degrees is 4% or less, and the maximum reflectance R 450-580 (40 deg _{) MAX} at an incident angle of 40 degrees is 6% or less. (i-5) At a wavelength of 450 to 500 nm, the maximum difference between the transmittance at an incident angle of 0 degrees and the transmittance at an incident angle of 40 degrees is 6% or less. (i-6) At a wavelength of 500 to 580 nm, the maximum difference between the transmittance at an incident angle of 0 degrees and the transmittance at an incident angle of 40 degrees is 5% or less. (i-7) At a wavelength of 450 to 580 nm, the average transmittance T _{450-580 (0 deg) AVE} is 88% or more (i-8) In the wavelength range of 600 to 800 nm, the absolute value of the difference between the wavelength at which the transmittance is 20% at an incident angle of 0 degrees and the wavelength at which the transmittance is 20% at an incident angle of 40 degrees is 10 nm or less (i-9) In the wavelength range of 600 to 800 nm, the wavelength at which the transmittance is 20% at an incident angle of 0 degrees is in the range of 640 to 690 nm (i-10) In the wavelength range of 750 to 1000 nm, the maximum transmittance T _{750-1000 (0 deg) MAX} at an incident angle of 0 degrees is 1% or less, and the maximum transmittance T _{750-1000 (40 deg) MAX} at an incident angle of 40 degrees is 1% or less

The present invention provides an optical filter that has high visible light transmittance and high near-infrared light shielding properties, suppresses ripples even at high angles of incidence, and suppresses changes in shielding properties at high angles of incidence of near-infrared light.

FIG. 1 is a cross-sectional view illustrating an example of an optical filter according to an embodiment. FIG. 2 is a cross-sectional view illustrating a schematic configuration of another example of the optical filter according to the embodiment. FIG. 3 is a cross-sectional view illustrating a schematic configuration of another example of the optical filter according to the embodiment. FIG. 4 is a cross-sectional view illustrating a schematic configuration of another example of the optical filter according to the embodiment. FIG. 5 is a diagram showing the spectral transmittance curve of the dielectric multilayer film 1 of Example 2-1. FIG. 6 is a diagram showing the spectral transmittance curve of the dielectric multilayer film 2 of Example 2-2.

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, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas. The dye consisting of compound (I) is also referred to as dye (I), and the same applies to other dyes. In addition, the group represented by formula (I) is also referred to as group (I), and the same applies to groups represented by other formulas.

In this specification, the internal transmittance is the transmittance obtained by subtracting the influence of interface reflection from the actually measured transmittance, which is expressed by the formula {actual transmittance/(100-reflectance)}×100.
In this specification, the transmittance of a substrate, the transmittance of a resin film including a case where a dye is contained in the resin, and the spectrum of the transmittance measured by dissolving the dye in a solvent such as dichloromethane are all "internal transmittances" even when they are referred to as "transmittances." On the other hand, the transmittance of an optical filter having a dielectric multilayer film is an actually 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 is 90% or more in the wavelength range. 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 is 1% or less in the wavelength range. 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 the wavelength range.
The optical properties can be measured using a UV-Vis spectrophotometer.
In this specification, any numerical range expressed by "to" includes the upper and lower limits.

<Optical filter>
An optical filter according to one embodiment of the present invention (hereinafter also referred to as "this filter") is an optical filter that comprises a substrate and a dielectric multilayer film laminated as an outermost layer on at least one main surface side of the substrate, and that satisfies specific optical characteristics described below.
Here, the substrate has a resin film containing a dye (IR) having a maximum absorption wavelength in dichloromethane at 680 to 1000 nm, and a resin. The dye (IR) is a NIR dye. By containing a dye that absorbs near-infrared rays in the substrate, the degradation of the optical properties of the dielectric multilayer film at high angles of incidence, for example, the occurrence of light leakage and noise in the near-infrared region, can be compensated for by the absorption properties of the substrate. Each dye and resin will be described later.

An example of the configuration of the present filter will be described with reference to the drawings. Figures 1 to 4 are cross-sectional views that show an outline of an example of an optical filter according to an embodiment.
1 is an example of an optical filter 1A having a dielectric multilayer film 30 on one main surface side of a substrate 10. Note that "having a specific layer on the main surface side of the substrate" does not only mean that the layer is provided in contact with the main surface of the substrate, but also means that another functional layer is provided between the substrate and the layer.

The optical filter 1B shown in FIG. 2 is an example having a dielectric multilayer film 30 on both main surfaces of the substrate 10.

The optical filter 1C shown in FIG. 3 is an example in which the substrate 10 has a support 11 and a resin film 12 laminated on one of the main surfaces of the support 11. The optical filter 1C further has a dielectric multilayer film 30 on the resin film 12 and on the main surface of the support 11 on which the resin film 12 is not laminated.

The optical filter 1D shown in FIG. 4 is an example in which the substrate 10 has a support 11 and resin films 12 laminated on both main surfaces of the support 11. The optical filter 1D further has a dielectric multilayer film 30 on each of the resin films 12.

The optical filter of the present invention satisfies all of the following optical properties (i-1) to (i-10).
(i-1) At a wavelength of 450 to 500 nm, the average reflectance R _{450-500 (5 deg) AVE} at an incident angle of 5 degrees is 3% or less, and the average reflectance R _{450-500 (40 deg) AVE} at an incident angle of 40 degrees is 5% or less. (i-2) At a wavelength of 500 to 580 nm, the average reflectance R _{500-580 (5 deg) AVE} at an incident angle of 5 degrees is 2.5% or less, and the average reflectance R _{500-580 (40 deg) AVE} at an incident angle of 40 degrees is 4% or less. (i-3) The R _{450-500 (5 deg) AVE} > the R _{500-580 (5 deg) AVE} and the R _{450-500 (40 deg) AVE} > the R (i-4) At a wavelength of 450 to 580 nm, the maximum reflectance R _{450-580 (5 deg) MAX} at an incident angle of 5 degrees is 4% or less, and the maximum reflectance R 450-580 (40 deg _{) MAX} at an incident angle of 40 degrees is 6% or less. (i-5) At a wavelength of 450 to 500 nm, the maximum difference between the transmittance at an incident angle of 0 degrees and the transmittance at an incident angle of 40 degrees is 6% or less. (i-6) At a wavelength of 500 to 580 nm, the maximum difference between the transmittance at an incident angle of 0 degrees and the transmittance at an incident angle of 40 degrees is 5% or less. (i-7) At a wavelength of 450 to 580 nm, the average transmittance T _{450-580 (0 deg) AVE} is 88% or more (i-8) In the wavelength range of 600 to 800 nm, the absolute value of the difference between the wavelength at which the transmittance is 20% at an incident angle of 0 degrees and the wavelength at which the transmittance is 20% at an incident angle of 40 degrees is 10 nm or less (i-9) In the wavelength range of 600 to 800 nm, the wavelength at which the transmittance is 20% at an incident angle of 0 degrees is in the range of 640 to 690 nm (i-10) In the wavelength range of 750 to 1000 nm, the maximum transmittance T _{750-1000 (0 deg) MAX} at an incident angle of 0 degrees is 1% or less, and the maximum transmittance T _{750-1000 (40 deg) MAX} at an incident angle of 40 degrees is 1% or less

This filter, which satisfies all of the optical properties (i-1) to (i-10), is an optical filter that has excellent visible light transmittance and near-infrared light blocking properties, and also suppresses the generation of ripples and changes in near-infrared light blocking properties at a high incident angle of 40 degrees.

Satisfying the optical properties (i-1), (i-2) and (i-4) means that the reflectance in the visible light region is sufficiently low.
In the optical property (i-1), R _{450-500 (5 deg) AVE} is preferably 2.5% or less, and R _{450-500 (40 deg) AVE} is preferably 4.5% or less.
In the optical property (i-2), R _{500-580 (5 deg) AVE} is preferably 2% or less, and R _{500-580 (40 deg) AVE} is preferably 3.5% or less.
In the optical characteristics (i-4), R _{450-580 (5 deg) MAX} is preferably 3.5% or less, and R _{450-580 (40 deg) MAX} is preferably 5.5% or less.

Satisfying the optical characteristic (i-3) means that the reflectance in the green band, which is particularly important for the visibility of the imaging device sensor, is low.

Meeting the optical characteristic (i-7) means that the transmittance in the visible light region is high, and meeting the optical characteristics (i-1), (i-2), and (i-4) to (i-6) means that ripples are suppressed even at high angles of incidence.

The optical property (i-5) is preferably 5.5% or less, and more preferably 5% or less.
The optical property (i-6) is preferably 4.5% or less, and more preferably 4% or less.

T _{450-580 (0 deg) AVE} is preferably 89% or more, more preferably 90% or more.

Satisfying the optical property (i-8) means that there is little shift (i.e., change in the near-infrared light shielding property) even at a high incident angle in the near-infrared light absorption band of wavelengths of 600 to 800 nm, and color reproducibility is excellent.
The optical property (i-8) is preferably 8 nm or less, more preferably 6 nm or less.

Satisfying the optical characteristic (i-9) means that the infrared band can be blocked and visible transmitted light can be efficiently captured. The optical characteristic (i-9) is preferably in the range of 645 to 685 nm, and more preferably in the range of 650 to 680 nm.

Satisfying the optical characteristic (i-10) means that the light-shielding properties are excellent in the near infrared light to long wavelength region of 750 to 1000 nm, both at an incident angle of 0 degree and at a high incident angle of 40 degrees. _{T 750-1000 (0 deg) MAX} is preferably 0.95% or less, more preferably 0.9% or less. _{T 750-1000 (40 deg) MAX} is preferably 0.95% or less, more preferably 0.9% or less.

<Dielectric multilayer film>
In the present filter, the dielectric multilayer film is laminated as an outermost layer on at least one of the main surfaces of the substrate.

In the present filter, it is preferable that the dielectric multilayer film satisfies all of the following optical properties (iv-1) to (iv-8).
(iv-1) At a wavelength of 450 to 580 nm, the average transmittance T _{450-580 (0 deg) AVE} at an incident angle of 0 degrees is 90% or more, and the average transmittance T _{450-580 (40 deg) AVE} at an incident angle of 40 degrees is 90% or more. (iv-2) At a wavelength of 450 to 500 nm, the absolute value of the difference between the average transmittance at an incident angle of 0 degrees and the average transmittance at an incident angle of 40 degrees is 3% or less. (iv-3) At a wavelength of 500 to 580 nm, the absolute value of the difference between the average transmittance at an incident angle of 0 degrees and the average transmittance at an incident angle of 40 degrees is 2% or less. (iv-4) At a wavelength of 450 to 500 nm, the absolute value of the difference between the average transmittance at an incident angle of 0 degrees and the average transmittance at an incident angle of 40 degrees is 2% or less. (iv-5) At a wavelength of 500 to 580 nm, the maximum difference between the transmittance at an incident angle of 0 degrees and the transmittance at an incident angle of 40 degrees is 5% or less. (iv-6) At a wavelength of 600 to 800 nm, the wavelength at which the transmittance at an incident angle of 0 degrees is 20% is in the range of 720 to 770 nm. (iv-7) At a wavelength of 780 to 850 nm, the maximum transmittance T _{780-850 (0 deg) MAX} at an incident angle of 0 degrees is 4% or more and less than 10%. (iv-8) At a wavelength of 900 to 980 nm, the maximum transmittance T _{900-980 (40 deg) MAX} at an incident angle of 40 degrees is 1% or more and less than 5%.

Satisfying the optical characteristic (iv-1) means that the transmittance in the visible light region is excellent both at an incident angle of 0 degrees and at a high incident angle of 40 degrees.
T _{450-580 (0 deg) AVE} is preferably 91% or more, more preferably 92% or more.
T _{450-580 (40 deg) AVE} is preferably 90.5% or more, more preferably 91% or more.

By satisfying the optical properties (iv-2) to (iv-5), it is meant that the occurrence of ripples in the visible light region is suppressed even at a high incident angle of 40 degrees.
The optical property (iv-2) is preferably 2.5% or less, more preferably 2% or less.
The optical property (iv-3) is preferably 1.6% or less, more preferably 1.2% or less.
The optical property (iv-4) is preferably 5.5% or less, more preferably 5% or less.
The optical property (iv-5) is preferably 4.5% or less, more preferably 4% or less.

Satisfying the optical characteristic (iv-6) means that the transmittance in the red band is excellent and the light-shielding properties are excellent in the near-infrared light region from wavelength 770 nm onwards. The optical characteristic (iv-6) is preferably in the range of 725 to 765 nm, more preferably in the range of 730 to 760 nm.

The optical characteristics (iv-7) to (iv-8) define the permissible range of light leakage in the near-infrared light region.
T _{780-850 (0 deg) MAX} is preferably 4 to 9%, more preferably 4 to 8%.
T _{900-980 (40 deg) MAX} is preferably 1 to 4.5%, more preferably 1 to 4%.

As shown in the optical characteristics (iv-2) to (iv-5), the dielectric multilayer film of the present invention suppresses the occurrence of ripples in the visible light region even at a high incident angle of 40 degrees.
On the other hand, as shown in the optical characteristics (iv-7) to (iv-8) above, light leakage may occur at angles of incidence of 0 degrees and 40 degrees and in the near-infrared wavelength region of 780 nm or more. Since such wavelength region is covered by the absorption of the NIR dye in the resin film described later, even if light leakage occurs, the optical filter as a whole is light-shielded.

By combining such a dielectric multilayer film with a resin film described later, the optical filter of the present invention has high visible light transmittance as shown in the optical characteristic (i-7) and high near-infrared light shielding as shown in the optical characteristic (i-10), and as shown in the optical characteristics (i-1) to (i-2) and (i-4) to (i-6), ripples are suppressed even at high angles of incidence, and as shown in the optical characteristic (i-8), changes in shielding properties at high angles of incidence of near-infrared light are suppressed.

In this filter, at least one of the dielectric multilayer films is preferably designed as a near-infrared reflective layer (hereinafter also referred to as an NIR reflective layer). The other of the dielectric multilayer films is preferably designed as an NIR reflective layer, a reflective layer having a reflection range other than the near-infrared range, or an anti-reflection layer.

The NIR reflective layer is a dielectric multilayer film designed to block light in the near-infrared range. The NIR reflective layer has wavelength selectivity that transmits visible light and mainly reflects light in the near-infrared range other than the light-shielding range of the resin film that is the absorption layer. The reflective region of the NIR reflective layer may include the light-shielding region in the near-infrared range of the resin film. The NIR reflective layer is not limited to NIR reflection characteristics, and may be appropriately designed to further block light in wavelength ranges other than the near-infrared range, for example, the near-ultraviolet range.

The NIR reflective layer is, for example, composed of a dielectric multilayer film in which a dielectric film with a low refractive index (low refractive index film) and a dielectric film with a high refractive index (high refractive index film) are alternately laminated. The high refractive index film preferably has a refractive index of 1.6 or more, more preferably 2.2 to 2.5. Examples of materials for the high refractive index film include Ta ₂ O ₅ , TiO ₂ , and Nb ₂ O _5. Among these, TiO ₂ is preferred from the viewpoints of film formation, reproducibility in refractive index, stability, etc.

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 standpoint of reproducibility, stability, economy _, etc. in film formation.

To suppress ripples even at high angles of incidence, but allow light leakage in the near-infrared wavelength region of 780 nm and above, a multilayer film can be made with a reduced number of layers, for example.

In the NIR reflective layer, the total number of laminated layers of the dielectric multilayer film constituting the reflective layer is preferably 20 or more, more preferably 25 or more, and even more preferably 30 or more, from the viewpoint of light shielding properties in the near-infrared wavelength region. However, since a large total number of laminated layers may cause ripples or warping or an increase in film thickness, the total number of laminated layers is preferably 100 or less, more preferably 75 or less, and even more preferably 60 or less.
Moreover, the thickness of the reflective layer is preferably 2 to 10 μm as a whole from the viewpoint of reducing warping of the optical filter.

The dielectric multilayer film can be formed using vacuum deposition processes such as CVD, sputtering, and vacuum deposition, or wet deposition processes such as spraying and dipping.

The NIR reflective layer may be one layer (a group of dielectric multilayer films) that imparts the desired optical characteristics, or two layers that impart the desired optical characteristics. When there are two or more 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. When there are two reflective layers, 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.

Examples of anti-reflection 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 standpoint of optical efficiency and productivity. Anti-reflection layers are obtained by alternately stacking dielectric multilayer films, just like reflective layers.

<Substrate>
In the optical filter of the present invention, the substrate has a resin film containing an NIR dye (IR) and a resin, which will be described later.

<Optical properties of resin film>
It is preferable that the resin film satisfies all of the following optical properties (ii-1) to (ii-6).
(ii-1) Average internal transmittance T _{450-580 AVE} at wavelengths of 450 to 580 nm is 88% or more; (ii-2) At wavelengths of 600 to 700 nm, the wavelength at which the internal transmittance is 20% is in the range of 640 to 690 nm; (ii-3) Internal transmittance T ₇₀₀ at a wavelength of 700 nm is 1% or less; (ii-4) Internal transmittance T ₇₅₀ at a wavelength of 750 nm is 10% or less; (ii-5) Internal transmittance T ₈₀₀ at a wavelength of 800 nm is 20% or less; (ii-6) Internal transmittance T ₉₅₀ at a wavelength of 950 nm is 60% or more and 95% or less.

Satisfying the optical characteristic (ii-1) means that the transmittance in the visible light region is high.
T _450-580AVE is preferably 89% or more, more preferably 90% or more.

Satisfying the optical characteristic (ii-2) means that it is possible to compensate for the oblique incidence shift of a dielectric multilayer film that has excellent transmittance in the red band and excellent light blocking properties in the near-infrared light region with wavelengths of 700 nm and above.
The optical property (ii-2) is preferably in the range of 645 to 685 nm, more preferably 650 to 680 nm.

By satisfying the optical properties (ii-3) to (ii-5), it is possible to block light by absorption in the wavelength range in which light leakage is likely to occur in the dielectric multilayer film.
_T700 is preferably 0.9% or less.
T ₇₅₀ is preferably 9.5% or less, more preferably 9% or less.
T ₈₀₀ is preferably 18% or less, more preferably 16% or less.

The optical property (ii-6) defines the range of transmittance permitted in the long wavelength region.
T ₉₅₀ is preferably 60% or more and 92.5% or less, more preferably 60% or more and 90% or less.

<NIR Dye>
The NIR dye (IR) is a NIR dye that has a maximum absorption wavelength in dichloromethane at 680 to 1000 nm. By including such a dye, near-infrared light can be effectively blocked.

The dye (IR) preferably satisfies the following characteristic (iii-1) in a spectral internal transmittance curve measured by dissolving the dye (IR) in a resin so that the internal transmittance at the maximum absorption wavelength in the resin constituting the resin film is 10%.
(iii-1) When the maximum absorption wavelength in the resin is D [nm] and the average internal transmittance in the range of 450 to 580 nm is E, E>100-(D/100).

The dye (IR) has a maximum absorption wavelength in the near-infrared region, but the larger the maximum absorption wavelength, the easier it is to absorb visible light, so the transmittance in the visible region tends to decrease. The characteristic (iii-1) specifies the relationship between the maximum absorption wavelength and the lower limit of the visible light transmittance. Therefore, if the dye (IR) satisfies the characteristic (iii-1), it means that the visible light transmittance is sufficiently high.
The property (iii-1) is more preferably E>101.5-(D/100).

The NIR dye (IR) may be composed of one type of compound, or may contain two or more types of compounds. From the viewpoint of easily satisfying the optical properties (ii-3) to (ii-6) of the resin film, that is, absorbing light in a wide wavelength range of 700 to 1000 nm, it is preferable to contain three or more types of compounds having a maximum absorption wavelength in dichloromethane at 680 to 1000 nm, and more preferably to contain one or more compounds selected from each of the following compounds (A) to (C):
Compound (A): A compound having a maximum absorption wavelength in dichloromethane at a wavelength of 690 nm or more and less than 735 nm. Compound (B): A compound having a maximum absorption wavelength in dichloromethane at a wavelength of 735 nm or more and less than 835 nm. Compound (C): A compound having a maximum absorption wavelength in dichloromethane at a wavelength of 900 nm or more and less than 1000 nm.

In addition, the maximum difference between the maximum absorption wavelength of compound (A) and the maximum absorption wavelength of compound (B) is preferably 40 nm or more, more preferably 50 nm or more. This allows efficient light blocking by absorption in the wavelength range where light leakage through the dielectric multilayer film is likely to occur.

From the viewpoints of transmittance in the visible light range, solubility in resin, and durability, it is preferable that compound (A) is selected from at least one of squarylium compounds and cyanine compounds, compound (B) is selected from at least one of squarylium compounds and cyanine compounds, and compound (C) is selected from at least one of squarylium compounds, cyanine compounds, and immonium compounds.

<Squarylium Compounds>
The squarylium compound is preferably a compound represented by the following formula (I), a compound represented by formula (II) described below, or a compound represented by formula (V) described below.
When two or more identical symbols are present in a squarylium compound, those symbols may be the same or different. The same applies to a cyanine compound.

<Squarylium compound (I)>

Here, the symbols in the above formula are as follows:
R ²⁴ and R ²⁶ 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, an araryl group having 7 to 18 carbon atoms which may have a substituent and which may have an oxygen atom between the carbon atoms, -NR ²⁷ R ²⁸ (R ²⁷ and R ²⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, -C(═O)-R ²⁹ (R ²⁹ represents 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 and ^{R 30} each represent 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 carboxy 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 each independently represent a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group having 1 to 10 carbon atoms; k is 2 or 3).

R ²¹ and R ²² , R ²² and R ²⁵ , and R ²¹ and R ²³ may be linked to each other to form, together with the nitrogen atom, a 5- or 6-membered heterocycle A, a heterocycle B, and a heterocycle C, respectively.
When a heterocycle A is formed, R ²¹ and R ²² bond to each other to form a divalent group -Q-, which is an alkylene 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, or an alkyleneoxy group.
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), the four Z's each independently represent a hydrogen atom, ^a hydroxyl group, an alkyl group or an alkoxy group having 1 to 6 carbon atoms, or ^-NR38R39 ( ^R38 and ^R39 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms). ^R31 to ^R36 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 ^R37 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 not forming ^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 an 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 araryl 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 compound (I) include compounds represented by any of formulas (I-1) to (I-3). From the viewpoints of solubility in the resin, heat resistance and light resistance in the resin, and the visible light transmittance of the resin layer containing it, the compound represented by formula (I-1) is particularly preferred.

The symbols in formulas (I-1) to (I-3) are the same as those in formula (I), and the preferred embodiments are also the same.

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(CH ₃ ) ₂ -CH(C ₂ H ₅ )-...(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 the compound (I-1), from the viewpoints of solubility, heat resistance, and steepness of change in the vicinity of the boundary between the visible region and the near-infrared region in the spectral transmittance curve, R ²¹ is more preferably independently a group represented by formula (4-1) or (4-2).

In formula (4-1) and formula (4-2), R ⁷¹ to R ⁷⁵ independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms.

In the compound (I-1), R ²⁴ is preferably —NR ²⁷ R ^28. —NR ²⁷ R ²⁸ is preferably —NH—C(═O)—R ²⁹ or —NH—SO ₂ —R ³⁰ from the viewpoint of solubility in the resin and the coating solvent.

In compound (I-1), a compound in which R ²⁴ is —NH—C(═O)—R ²⁹ is shown in formula (I-11).

R ²³ and R ²⁶ are each preferably 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.

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 araryl 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 hydroxyl group, a carboxy 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 group selected from a linear, branched or cyclic alkyl group having 1 to 17 carbon atoms, a phenyl group which may be substituted with an alkoxy group having 1 to 6 carbon atoms, and an araryl group having 7 to 18 carbon atoms which may have an oxygen atom between the carbon atoms.

As R ²⁹ , a group which is 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 hydroxyl group, a carboxy 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, can also be preferably used.

More specifically, examples of compound (I-11) include the compounds shown in the table below. In addition, in the compounds shown in the table below, the meanings of the symbols on the left and right of the squarylium skeleton are the same.

Among these, compounds (I-11-11) to (I-11-15) and (I-11-26) to (I-11-30) are preferred as compound (I-11) from the viewpoints of transparency in the visible light range and solubility in resin.

In compound (I-1), a compound in which R ²⁴ is —NH—SO ₂ —R ³⁰ is shown in formula (I-12).

R ²³ and R ²⁶ are each preferably 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.

From the viewpoint of light resistance, R ³⁰ is preferably an alkyl group 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 the unsaturated ring structure include benzene, toluene, xylene, furan, and benzofuran. R ³⁰ is more preferably an alkyl group 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.

More specifically, examples of compound (I-12) include the compounds shown in the table below. In addition, in the compounds shown in the table below, the meanings of the symbols on the left and right of the squarylium skeleton are the same.

Among these, compounds (I-12-11) to (I-12-15) and (I-12-26) to (I-12-30) are preferred as compound (I-12) from the viewpoints of transparency in the visible light range and solubility in resins.

<Squarylium compound (II)>

Here, the symbols in the above formula are as follows:
Each ring Z is independently a 5- or 6-membered ring having 0 to 3 heteroatoms in the ring, and the hydrogen atoms in ring Z may be substituted.
R ¹ and R ² , R ² and R ³ , and R ¹ and the carbon atom or hetero atom constituting ring Z may be linked together to form heterocycle A1, heterocycle B1, and heterocycle C1, respectively, together with the nitrogen atom, in which case the hydrogen atoms in heterocycle A1, heterocycle B1, and heterocycle C1 may be substituted. When no heterocycle is formed, R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, or a hydrocarbon group that may contain an unsaturated bond, a heteroatom, or a saturated or unsaturated ring structure between carbon atoms and may have a substituent. When no heterocycle is formed, ^{R 4} and R ³ each independently represent a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group that may contain a heteroatom between carbon atoms and may have a substituent.

Examples of compound (II) include compounds represented by any of formulas (II-1) to (II-3), and from the viewpoints of solubility in the resin and visible light transmittance in the resin, the compound represented by formula (II-3) is particularly preferred.

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 compound (II-1) and compound (II-2), from the viewpoints of solubility in resin, 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, further 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.

In the compound (II-3), from the viewpoints of solubility in a transparent 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, R ⁴ is preferably a hydrogen atom or a halogen atom, and particularly preferably a hydrogen atom.
R ⁷ and R ⁸ 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.

R ⁹ to R ¹² are preferably each 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 divalent organic groups represented by the following groups (13-1) to (13-5).
-CH( _CH3 )-C( _CH3 ) ₂ -...(13-1)
-C(CH ₃ ) ₂ -CH(CH ₃ )-...(13-2)
-C( _CH3 ) ₂ - _CH2 -...(13-3)
-C(CH ₃ ) ₂ -CH(C ₂ H ₅ )-...(13-4)
-CH( _CH3 )-C( _CH3 )( _CH2 -CH( _CH3 ) ₂ )-...(13-5)

More specifically, examples of compound (II-3) include the compounds shown in the table below. In addition, in the compounds shown in the table below, the meanings of the symbols on the left and right of the squarylium skeleton are the same.

Compounds (I) to (II) can each be produced by a known method. Compound (I) can be produced by the method described in U.S. Pat. No. 5,543,086, 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.

<Cyanine Compound>
The cyanine compound is preferably a compound represented by the following formula (III) or formula (IV).

<Cyanine compounds (III) and (IV)>

Here, the symbols in the above formula are as follows:
R ¹⁰¹ to R ¹⁰⁹ and R ¹²¹ to R ¹³¹ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms. R ¹¹⁰ to R ¹¹⁴ and R ¹³² to R ¹³⁶ each independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 15 carbon atoms.
X ⁻ represents a monovalent anion.
n1 and n2 are 0 or 1. A hydrogen atom bonded to the carbocycle containing -(CH ₂ ) _n1 - and the carbocycle containing -(CH ₂ ) _n2 - may be substituted with a halogen atom, an alkyl group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms.

In the above, the alkyl group (including the alkyl group of the alkoxy group) may be linear or may have a branched structure or a saturated ring structure. The aryl group refers to a group that bonds via a carbon atom that constitutes an aromatic ring of an aromatic compound, such as a benzene ring, a naphthalene ring, a biphenyl, a furan ring, a thiophene ring, or a pyrrole ring. Examples of the substituents in the alkyl group or alkoxy group having 1 to 15 carbon atoms, which may have a substituent, or the aryl group having 5 to 20 carbon atoms, include halogen atoms and alkoxy groups having 1 to 10 carbon atoms.

In formula (III) and formula (IV), R ¹⁰¹ and R ¹²¹ are preferably an alkyl group having 1 to 15 carbon atoms or an aryl group having 5 to 20 carbon atoms, and more preferably a branched alkyl group having 1 to 15 carbon atoms from the viewpoint of maintaining a high visible light transmittance in the resin.

In formula (III) and formula (IV), R ¹⁰² to R ¹⁰⁵ , R ¹⁰⁸ , R ¹⁰⁹ , R ¹²² to R ¹²⁷ , R ¹³⁰ and R ¹³¹ each independently represent preferably a hydrogen atom, an alkyl or alkoxy group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms, and more preferably a hydrogen atom from the viewpoint of obtaining a high visible light transmittance.

In formulae (III) and (IV), R ¹¹⁰ to R ¹¹⁴ and R ¹³² to R ¹³⁶ each independently preferably represent a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, and more preferably a hydrogen atom from the viewpoint of obtaining a high visible light transmittance.

R ¹⁰⁶ , R ¹⁰⁷ , R ¹²⁸ and R ¹²⁹ are each independently preferably a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms (which may include a linear, cyclic or branched alkyl group), more preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms. It is also preferable that R ¹⁰⁶ and R ¹⁰⁷ , and R ¹²⁸ and R ¹²⁹ are the same group.

Examples of X ⁻ include I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , and anions represented by the formulae (X1) and (X2), and preferably BF ₄ ⁻ or PF ₆ ⁻ .

In the following explanation, the portion of compound (III) excluding R ¹⁰¹ to R ¹¹⁴ is also referred to as skeleton (III), and the same applies to compound (IV).

In formula (III), compounds where n1 is 1 are shown in formula (III-1) below, and compounds where n1 is 0 are shown in formula (III-2) below.

In formula (III-1) and formula (III-2), R ¹⁰¹ to R ¹¹⁴ and X ^- are the same as in formula (III). R ¹¹⁵ to R ¹²⁰ each independently represent a hydrogen atom, a halogen atom, an alkyl group or alkoxy group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms. R ¹¹⁵ to R ¹²⁰ each independently represent preferably a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms (which may include a linear, cyclic, or branched alkyl group), more preferably a hydrogen atom, or an alkyl group having 1 to 15 carbon atoms. In addition, R ¹¹⁵ to R ¹²⁰ are preferably the same group.

In formula (IV), compounds where n2 is 1 are shown in formula (IV-1) below, and compounds where n2 is 0 are shown in formula (IV-2) below.

In formula (IV-1) and formula (IV-2), R ¹²¹ to R ¹³⁶ and X ^- are the same as in formula (IV). R ¹³⁷ to R ¹⁴² each independently represent a hydrogen atom, a halogen atom, an alkyl group or alkoxy group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms. R ¹³⁷ to R ¹⁴² each independently represent preferably a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms (which may include a linear, cyclic, or branched alkyl group), more preferably a hydrogen atom, or an alkyl group having 1 to 15 carbon atoms. In addition, it is preferable that R ¹³⁷ to R ¹⁴² are the same group.

More specifically, the compounds represented by formula (III-1), formula (III-2), formula (IV-1), and formula (IV-2) each include compounds in which an atom or group bonded to each skeleton is an atom or group shown in the table below. In all compounds shown in the table below, R ¹⁰¹ to R ¹⁰⁹ are all the same on the left and right sides of the formula. In all compounds shown in the table below, R ¹²¹ to R ¹³¹ are the same on the left and right sides of the formula.

R ¹¹⁰ -R ¹¹⁴ in the table below and R ¹³² -R ¹³⁶ in the table below indicate atoms or groups bonded to the central benzene ring of each formula, and when all five are hydrogen atoms, it is written as "H". When any one of R ¹¹⁰ -R ¹¹⁴ is a substituent and the rest are hydrogen atoms, only the combination of the symbol that is the substituent and the substituent is written. For example, the description "R ¹¹² -C(CH ₃ ) ₃ " indicates that R ¹¹² is -C(CH ₃ ) ₃ and the rest are hydrogen atoms. The same applies to ^{R 132} -R ¹³⁶ .

R ¹¹⁵ -R ¹²⁰ in Table 4 and R ¹³⁷ -R ¹⁴² in Table 6 represent atoms or groups bonded to the central cyclohexane ring in formula (III-1) and formula (IV-1), and when all six are hydrogen atoms, they are represented as "H". When any one of R ¹¹⁵ -R ¹²⁰ is a substituent and the rest are hydrogen atoms, only the combination of the symbol representing the substituent and the substituent is represented. The same applies to R ¹³⁷ -R ¹⁴² .

R ¹¹⁵ -R ¹¹⁸ in Table 5 and R ¹³⁷ -R ¹⁴⁰ in Table 7 represent atoms or groups bonded to the central cyclopentane ring in formula (III-2) and formula (IV-2), and when all four are hydrogen atoms, they are represented as "H". When any one of R ¹¹⁵ -R ¹¹⁸ is a substituent and the rest are hydrogen atoms, only the combination of the symbol representing the substituent and the substituent is represented. The same applies to R ¹³⁷ -R ¹⁴⁰ .

In the following table, X ^- is not shown, but in all the compounds, X ^- is BF ₄ ^- or PF ₆ ^- .

Among these, compounds (III-1-1) to (III-1-5) are preferred as compound (III-1) in terms of transparency in the visible light range and solubility in resin.

Among these, compounds (III-2-1) to (III-2-5) are preferred as compound (III-2) in terms of transparency in the visible light range and solubility in resin.

Among these, compounds (IV-1-1) to (IV-1-5) are preferred as compound (IV-1) in terms of transparency in the visible light range and solubility in resin.

Among these, compounds (IV-2-1) to (IV-2-5) are preferred as compound (IV-2) in terms of transparency in the visible light range and solubility in resin.

As described above, compound (III) and compound (IV) have different skeletons, which results in different wavelength regions of maximum absorption. In compound (III), the maximum absorption wavelength is in the wavelength region of approximately 760 to 830 nm, depending on the types and combinations of atoms and groups bonded to the skeleton. In compound (IV), the maximum absorption wavelength is in the wavelength region of approximately 800 to 900 nm, depending on the types and combinations of atoms and groups bonded to the skeleton.

Furthermore, in compound (III), the maximum absorption wavelength differs when n1 of the skeleton is 1 from when n1 is 0. Although it depends on the types and combinations of atoms and groups bonded to the skeleton, when n1 is 1, the maximum absorption wavelength is in the wavelength region of approximately 760 to 800 nm, and when n1 is 0, the maximum absorption wavelength is in the wavelength region of approximately 800 to 830 nm.

Similarly, in compound (IV), the maximum absorption wavelength differs when n2 is 1 from when n2 is 0. Although it depends on the types and combinations of atoms and groups bonded to skeleton (IV-1), when n2 is 1, the maximum absorption wavelength is in the wavelength region of approximately 800 to 830 nm, and when n2 is 0, the maximum absorption wavelength is in the wavelength region of approximately 830 to 900 nm.

Compounds (III) and (IV) can be produced, for example, by the methods described in Dyes and Pigments 73 (2007) 344-352 and J. Heterocyclic Chem, 42, 959 (2005).

<Squarylium compounds (V)>

In formula (V), R ⁵¹ to R ⁵⁴ each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, an aryl group or an araryl group.
The alkyl group, aryl group or araryl group may have a substituent.
In addition, the alkyl group, aryl group, or araryl group may contain an unsaturated bond, an oxygen atom, an ester bond, an amide bond, or a thioamide bond between carbon atoms.
Furthermore, the alkyl group, aryl group, or araryl group may have an oxygen atom, an ester bond, an amide bond, or a thioamide bond at the end bonding to the thiophene ring.
R ⁵¹ and R ⁵² , R ⁵² and R ⁵³ , and R ⁵³ and R ⁵⁴ may be linked to each other to form a monocycle or a polycycle having 2 to 4 condensed rings, in which case a hydrogen atom bonded to the ring may be substituted with a substituent.

Halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc., with fluorine atoms and chlorine atoms being preferred.

When R ⁵¹ to R ⁵⁴ are each an alkyl group, the alkyl group preferably has 1 to 20 carbon atoms, more preferably has 1 to 15 carbon atoms, and further preferably has 1 to 12 carbon atoms.
When R ⁵¹ to R ⁵⁴ are each an aryl group, the aryl group preferably has 4 to 20 carbon atoms, more preferably has 4 to 17 carbon atoms, and further preferably has 4 to 14 carbon atoms.
When R ⁵¹ to R ⁵⁴ are each an araryl group, the group preferably has 5 to 20 carbon atoms, more preferably 5 to 18 carbon atoms, and even more preferably 5 to 15 carbon atoms.
When R ⁵¹ to R ⁵⁴ have a substituent, the above carbon number includes the carbon number of the substituent.

Examples of the substituents in R ⁵¹ to R ⁵⁴ include halogen atoms, hydroxyl groups, carboxy groups, sulfo groups, cyano groups, amino groups, N-substituted amino groups, nitro groups, alkoxycarbonyl groups, carbamoyl groups, N-substituted carbamoyl groups, imido groups, and alkoxy groups having 1 to 10 carbon atoms. When R ⁵¹ to R ⁵⁴ are aryl groups or araryl groups, the substituents are hydrogen atoms bonded to the aromatic ring or groups substituting hydrogen atoms of the alkyl groups contained therein, and further include aryl groups in addition to the above-mentioned substituents.

R ⁵¹ and R ⁵² , R ⁵² and R ⁵³ , and R ⁵³ and R ⁵⁴ may be linked to each other to form a monocycle or a polycycle having 2 to 4 condensed rings, in which case a hydrogen atom bonded to the ring may be substituted with a substituent.

When R ⁵² and R ⁵³ are linked together, the squarylium compound (V) has a structure in which a ring is formed between two thiophene rings to form at least three condensed rings. A hydrogen atom bonded to the ring formed by linking R ⁵² and R ⁵³ may be substituted with a substituent.
Examples of the substituent that replaces the hydrogen atom bonded to the ring formed by connecting R ⁵² and R ⁵³ include the same groups as the substituents in R ⁵¹ to R ⁵⁴ , and a phenyl group which may have a substituent. Examples of the substituent in the phenyl group include the same groups as the substituents in R ⁵¹ to R ⁵⁴ .

R ⁵⁵ and R ⁵⁶ are each independently an alkyl group or an araryl group which may have a substituent and which may contain an unsaturated bond between carbon atoms, an oxygen atom or a nitrogen atom, or R ⁵⁵ and R ⁵⁶ may be linked together to form a cycloheterocycle having 5 to 10 members together with the nitrogen atom, in which case a hydrogen atom bonded to the ring may be substituted with a substituent.

Examples of the substituents in R ⁵⁵ and R ⁵⁶ include the same substituents as those in R ⁵¹ to R ^54. When R ⁵⁵ and R ⁵⁶ are araryl groups, the alkyl groups contained therein may be further substituted with an aryl group.

When R ⁵⁵ and R ⁵⁶ are an alkyl group, the number of carbon atoms is preferably 1 to 20, more preferably 1 to 12, and even more preferably 1 to 10. From the viewpoint of visible light transmittance and solubility in resins and solvents, R ⁵⁵ and R ⁵⁶ are preferably linear, branched, or cyclic alkyl groups having 3 to 20 carbon atoms and which may contain an oxygen atom between the carbon-carbon atoms. The number of carbon atoms in the alkyl group is more preferably 3 to 12 in the case of a linear group, more preferably 3 to 10 in the case of a branched group, and more preferably 5 to 10 in the case of a cyclic group. When R ¹⁵ and R ¹⁶ have a substituent, the number of carbon atoms in the substituent is included in the number of carbon atoms in the above-mentioned carbon group.
R ⁵⁵ and R ⁵⁶ are, for example, more preferably a group selected from groups (1a) to (15a), and particularly preferably group (1a).

R ⁵⁵ and R ⁵⁶ may be linked together to form a cyclohetero ring having 5 to 10 members together with the nitrogen atom. The cyclohetero ring may contain an oxygen atom in addition to the nitrogen atom as a ring-constituting element. The number of members of the cyclohetero ring is preferably 5 or 6, and particularly preferably 5. When a hydrogen atom bonded to the cyclohetero ring is substituted, examples of the substituent substituting the hydrogen atom include a halogen atom, a hydroxyl group, an alkyl group or an alkoxy group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aryl group having 7 to 20 carbon atoms.

When the divalent group to which R ⁵⁵ and R ⁵⁶ are bonded is represented by -Q-, specific examples of -Q- include the following groups (11) to (14).

-( _CH2 ) ₄ -...(11)
-( _CH2 ) ₅ -...(12)
-C( _CH3 ) ₂ ( _CH2 ) _2C ( _CH3 ) ₂ -...(13)
-C( _CH3 ) ₂ ( _CH2 ) _3C ( _CH3 ) ₂ -...(14)

As the squarylium compound (V), for example, a compound represented by the following formula (V-1) or a compound represented by the following formula (V-2) is preferable. The squarylium compound (V-1) is a squarylium compound (V) in which R ⁵² and R ⁵³ are linked to form a cyclopentadithiophene ring. The squarylium compound (V-2) is a squarylium compound (V) in which R ⁵² and R ⁵³ are not linked to each other and which includes a structure in which two thiophene rings are bonded.

R ⁵¹ , R ⁵⁴ , R ⁵⁵ and R ⁵⁶ are the same as R ⁵¹ , R ⁵⁴ , R ⁵⁵ and R ⁵⁶ in formula (V), including preferred embodiments thereof.
R ^52b and R ^53b are the same as R ⁵² and R ⁵³ in formula (V), including preferred embodiments, except that they are not linked to each other to form a ring.

From the viewpoints of visible light transmittance, light resistance, and solubility in resins and solvents, R ^52a and R ^53a are preferably linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms and which may contain an oxygen atom between the carbon atoms. The number of carbon atoms in the alkyl group is more preferably 1 to 12 in the case of a linear group, more preferably 3 to 10 in the case of a branched group, and more preferably 5 to 10 in the case of a cyclic group. R ^52a and R ^53a are more preferably groups selected from groups (1a) to (15a), for example, and particularly preferably group (1a), group (3a), or group (9a).

From the viewpoint of transmittance in the visible light region and light resistance, R ^52a and R ^53a are preferably a phenyl group which may have 1 to 5 substituents, a naphthyl group which may have 1 to 7 substituents, or an alkyl group having 1 to 10 carbon atoms. Examples of the substituents of the phenyl group and naphthyl group include an alkyl group having 1 to 12 carbon atoms, which may contain an unsaturated bond or an oxygen atom between the carbon-carbon atom, an alkoxy group, or an alkylamino group (the alkyl group has 1 to 12 carbon atoms), and in particular, a methyl group, a tertiary butyl group, a dimethylamino group, a methoxy group, etc. are preferred. The phenyl group and naphthyl group are preferably unsubstituted or substituted with 1 to 3 hydrogen atoms.

Specific examples of phenyl groups that may have 1 to 5 substituents include groups (P1) to (P9).

Specific examples of naphthyl groups that may have 1 to 7 substituents include groups (N1) to (N9).

More specifically, examples of compound (V-1) include the compounds shown in the table below. In addition, in the compounds shown in the table below, the meanings of the symbols on the left and right of the squarylium skeleton are the same.

Among these, compounds (V-1-5), (V-1-12), etc. are preferred as compound (V-1) in terms of transparency in the visible light range and solubility in resin.

More specifically, examples of compound (V-2) include the compounds shown in the table below. In addition, in the compounds shown in the table below, the meanings of the symbols on the left and right of the squarylium skeleton are the same.

The squarylium compound (V) can be produced by a known method. For example, it can be produced by the method described in WO 2019/230660.

<Imonium compounds>
The immonium compound is preferably a compound represented by the following formula (A1) or formula (A2).

The symbols in formulae (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 phosphoric acid group, an alkyl group or alkoxy group having 1 to 20 carbon atoms which may have an oxygen atom between the 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. However, groups in which a substituted or unsubstituted amino group is bonded to a phenyl group are excluded. Furthermore, in R ²⁰¹ to R ²⁰⁶ and R ²²¹ to R ²²⁶ , two groups bonded to the same nitrogen atom may be bonded 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 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 the 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 or an aromatic ring, or may be a heterocyclic ring. Examples of the heteroatom 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 of the three phenyl groups bonded to the central nitrogen atom in formula (A1) and formula (A2). Specifically, in formula (A1), there are six pairs of 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 pair, or two or more pairs, or up to six pairs may be bonded. It is preferable that one pair each for three phenyl groups is bonded, for a total of three pairs.

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 may have an unsaturated bond between atoms. More specific examples include the following groups (X-1) to (X-4). The hydrogen atoms in these divalent groups may be substituted with alkyl groups having 1 to 12 carbon atoms.

-( _CH2 ) _n- (n is an integer from 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, and more preferably a hydrogen atom, or an alkyl or alkoxy group having 1 to 12 carbon atoms. The number of carbon atoms in the alkyl or alkoxy group is preferably 1 to 6, and more preferably 1 to 4.

In addition, 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 heterocycle having 4 to 8 members 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 groups in the aryl groups below that have an alkyl group, and to the alkyl groups in the aralkyl groups. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, with fluorine atoms and chlorine atoms being preferred.

In the above, the aryl group refers to a group that bonds via a carbon atom that constitutes an aromatic ring (not including a heteroatom) of an aromatic compound, such as a benzene ring, a naphthalene ring, or a biphenyl ring. The aryl group includes a structure in which a hydrogen atom that is bonded to a ring-constituting atom other than the carbon atom that contributes to the bond is substituted with an alkyl group, such as a tolyl group or a xylyl group.

In the above, the aralkyl group refers to a group in which an alkyl group is bonded to an aromatic ring (but does not contain a heteroatom) via a carbon atom that constitutes the alkyl group. The aralkyl group includes a structure in which a hydrogen atom that is 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 ring or aromatic ring consisting of carbon atoms and atoms other than carbon atoms. The heterocyclic group includes a structure in which hydrogen atoms bonded to ring-constituting atoms other than the atoms contributing to the bond are substituted with alkyl groups. Examples of atoms other than carbon atoms contained in the heterocyclic ring include oxygen atoms, nitrogen atoms, and sulfur atoms, and the number of atoms is preferably 1 to 2.

^Xa- and ^Xb- each independently include Cl- ^, Br- ^, I- ^{, F-} _, ^ClO4- _{, BF4- , PF6-} ^, _SbF6- ^, _CF3SO3- ^{, CH3C6H4SO3-} _, N[ _SO2Rf ^] _2- , _C [ _{SO2Rf ]} ^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 viewpoint 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- ^{, BF4-} , _SbF6- , ^PF6- _{, ClO4-} ^, N[ _SO2CF3 ^] _2- ^, C[ _{SO2CF3 ] 3-} ^, etc., more preferably _SbF6- , _PF6- and N[ _SO2CF3 ^] _2- in terms ^of the small difference in optical properties between the dichloromethane solution and the resin, ^and particularly preferably _SbF6- and _N ^[ _SO2CF3 ] ^2- . Also, _{from the} viewpoint of light durability _, ^BF4- , _PF6- ^and N[ _SO2CF3 ] _2- ^are _preferred .

The content of the NIR dye (IR) in the resin film is preferably 0.1 to 25 parts by mass, more preferably 0.3 to 15 parts by mass, per 100 parts by mass of the resin. When two or more types of compounds are combined, the above content is the sum of the amounts of the compounds.
Furthermore, when the NIR dye (IR) contains the compounds (A) to (C), the content of the compound (A) is preferably 0.1 to 5 parts by mass, the content of the compound (B) is preferably 0.1 to 5 parts by mass, and the content of the compound (C) is preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the resin.

<Other dyes>
The resin film may contain other dyes, such as UV dyes, in addition to the NIR dye.
Specific examples of the UV dye 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, triazole-based dyes, etc. Furthermore, the UV dye may be used alone or in combination of two or more kinds.

<Base material composition>
The substrate in the present filter may have a single-layer structure or a multi-layer structure, and the material of the substrate is not particularly limited and may be an organic or inorganic material as long as it is a transparent material that transmits visible light of 400 to 700 nm.
When the substrate has a single layer structure, a resin substrate made of a resin film containing a resin and a NIR dye (IR) is preferred.
When the substrate has a multi-layer structure, it is preferably a composite substrate having a resin film containing an NIR dye (IR) laminated on at least one main surface of the support. In this case, the support is preferably made of a transparent resin or a transparent inorganic material.

The resin is not limited as long as it is a transparent resin, and one or more transparent resins selected from polyester resin, acrylic resin, epoxy resin, ene-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polyparaphenylene resin, polyarylene ether phosphine oxide resin, polyamide resin, polyimide resin, polyamideimide resin, polyolefin resin, cyclic olefin resin, polyurethane resin, polystyrene resin, etc. may be used. One of these resins may be used alone, or two or more may be used in combination.
From the viewpoints of the optical properties, glass transition point (Tg) and adhesion of the resin film, one or more resins selected from polyimide resins, polycarbonate resins, polyester resins and acrylic resins are preferred.

When multiple compounds are used as NIR dyes (IR) or other dyes, they may be contained in the same resin film, or each may be contained in a separate resin film.

As the transparent inorganic material, glass or a crystalline material is preferable.
Examples of glass that can be used for the support include absorption-type glass (near-infrared absorbing glass) containing copper ions in fluorophosphate glass or phosphate glass, soda-lime glass, borosilicate glass, non-alkali glass, and quartz glass.
As the glass, phosphate glass and fluorophosphate glass are preferable from the viewpoint of absorbing infrared light (especially 900 to 1200 nm). 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 exchanging alkali metal ions (e.g., Li ions, Na ions) with a small ionic radius present on the main surface of the glass sheet with alkali ions with a larger ionic radius (e.g., Na ions or K ions for Li ions, and K ions for Na ions) through ion exchange at a temperature below the glass transition point.

Crystal materials that can be used for the support include birefringent crystals such as quartz, lithium niobate, and sapphire.

As the support, inorganic materials are preferred from the viewpoint of shape stability related to the long-term reliability of optical properties, mechanical properties, etc., and handling properties during filter production, and glass and sapphire are particularly preferred.

The resin film can be formed by dissolving or dispersing the dye (IR), the resin or the raw material components of the resin, and each component that is mixed as necessary in a solvent to prepare a coating liquid, applying this to a support, drying it, and further curing it as necessary. The support may be the support included in this filter, or it may be a peelable support that is used only when forming the resin film. The solvent may be a dispersion medium in which the dye can be stably dispersed or a solvent in which the dye can be dissolved.

The coating liquid may also contain a surfactant to improve voids caused by tiny bubbles, depressions caused by the adhesion of foreign matter, and repellency during the drying process. For example, the dip coating method, cast coating method, spin coating method, etc. can be used to apply the coating liquid. After the coating liquid is applied onto the support, a resin film is formed by drying. If the coating liquid contains raw materials for a transparent resin, a curing process such as heat curing or light curing is further performed.

The resin film can also be manufactured into a film shape by extrusion molding. When the substrate is a single-layer structure (resin substrate) consisting of a resin film containing a dye (IR), the resin film may be used as is as the substrate. When the substrate is a multi-layer structure (composite substrate) having a support and a resin film containing a dye (IR) laminated on at least one main surface of the support, the substrate can be manufactured by laminating this film onto the support and integrating them by thermocompression or the like.

The optical filter may have one resin film layer or two or more resin films. When the optical filter has two or more resin films, each layer may have the same or different configurations.

When the substrate has a single-layer structure (resin substrate) made of a resin film containing a dye (IR), the thickness of the resin film is preferably 20 to 150 μm.
When the substrate is a multi-layer structure (composite substrate) having a support and a resin film containing a dye (IR) laminated on at least one main surface of the support, the thickness of the resin film is preferably 0.3 to 20 μm. When the optical filter has two or more resin films, the total thickness of the resin films is preferably within the above range.

The shape of the substrate is not particularly limited, and may be a block, plate, or film.
In addition, the thickness of the substrate is preferably 300 μm or less from the viewpoints of reducing warping during formation of the dielectric multilayer film and reducing the height of the optical element. When the substrate is a resin substrate made of a resin film, the thickness is preferably 50 to 300 μm. When the substrate is a composite substrate comprising a support and a resin film, the thickness is preferably 50 to 300 μm.

The filter may also include other components (layers) that provide absorption by inorganic fine particles that control the transmission and absorption of light in a specific wavelength range. Specific examples of inorganic fine particles include ITO (indium tin oxide), ATO (antimony-doped tin oxide), cesium tungstate, lanthanum boride, etc. ITO fine particles and cesium tungstate fine particles have high visible light transmittance and light absorption over a wide range of infrared wavelengths exceeding 1200 nm, so they can be used when blocking such infrared light is required.

Next, the present invention will be described more specifically with reference to examples.
The optical properties were measured using an ultraviolet-visible spectrophotometer (UH-4150, manufactured by Hitachi High-Technologies Corporation).
In addition, unless the angle of incidence is specifically stated, the optical characteristics are values measured at an angle of incidence of 0 degrees (perpendicular to the principal surface of the optical filter).

The dyes used in each example are as follows:
Compound 1 (squarylium compound): synthesized based on U.S. Patent Application Publication No. 2014/0061505 and WO 2014/088063.
Compound 2 (phthalocyanine compound): Synthesized based on Japanese Patent No. 4,081,149.
Compound 3 (squarylium compound): Synthesized based on WO 2017/135359.
Compounds 4 to 6 (cyanine compounds): Synthesized based on Dyes and pigments 73 (2007) 344-352.
Compound 7 (squarylium compound): Synthesized based on WO 2019/230660.
Compound 8 (diimonium compound): Synthesized based on JP 2014-25016 A.

Optical Properties of IR Dyes
A polyimide resin (C-3G30G manufactured by Mitsubishi Gas Chemical Co., Ltd.) was dissolved in an organic solvent (cyclohexanone:γ-butyrolactone=1:1 mass ratio) at a concentration of 8.5 mass %.
To the polyimide resin solution prepared above, each dye compound was added in an amount of 6 parts by mass per 100 parts by mass of the resin, and the mixture was stirred for 2 hours while heating to 50° C. The dye-containing resin solution was applied to a glass substrate (alkali glass, Schott D263) and dried to obtain a resin film (coated film) having a thickness of 1 μm.
Using the spectral transmittance curve and the spectral reflectance curve of this resin-coated glass plate, a spectral internal transmittance curve was calculated and normalized so that the transmittance at the maximum absorption wavelength was 10%.
The optical properties are shown in the table below.

<Examples 1-1 to 1-5: Optical properties of resin film>
A polyimide resin (C-3G30G manufactured by Mitsubishi Gas Chemical Co., Ltd.) was dissolved in an organic solvent (cyclohexanone:γ-butyrolactone=1:1 mass ratio) at a concentration of 8.5 mass %.
To the polyimide resin solution prepared above, each compound was added in an amount (parts by mass) shown in the table below relative to 100 parts by mass of the resin, and the mixture was stirred for 2 hours while heating to 50° C. The dye-containing resin solution was applied to a glass substrate (alkali glass, D263 manufactured by Schott) and dried to obtain a resin film (coated film) with a thickness of 2 μm.
The obtained resin film was subjected to measurement of transmission spectroscopy at an incident angle of 0° and reflection spectroscopy at an incident angle of 5° in the wavelength range of 350 nm to 1200 nm. The transmittance was expressed as the internal transmittance represented by the following formula.
Internal transmittance = measured transmittance / (100 - reflectance) * 100
The optical properties are shown in the table below.
Examples 1-1 to 1-5 are reference examples.

In Examples 1-1 to 1-3, only the amount of dye necessary to absorb light in the near-infrared region where light leakage can occur in the multilayer film is blended, and therefore the visible light transmittance is high.
In Example 1-4, the amount of dye blended is small, so that the near-infrared light region, which can cause light leakage in the multilayer film, is not completely absorbed.
Example 1-5 has a wide absorption band in the near infrared region, but a low visible light transmittance. This is presumably because the amount of dye added was increased to broaden the absorption band, resulting in absorption in the visible region as well.

<Examples 2-1 to 2-2: Optical properties of dielectric multilayer films>
Dielectric multilayer film 1 was designed to have a total thickness of 3.94 μm by laminating 32 TiO ₂ films and SiO ₂ films alternately, and dielectric multilayer film 2 was designed to have a total thickness of 4.94 μm by laminating 40 layers.
The optical characteristics of the dielectric multilayer film 1 and the dielectric multilayer film 2 are shown in the table below.
The spectral transmittance curves of the dielectric multilayer film 1 and the dielectric multilayer film 2 are shown in FIG. 5 and FIG.
It should be noted that Examples 2-1 and 2-2 are reference examples.

The dielectric multilayer film 1 has small ripples, but light leakage occurs at wavelengths of 780 nm and above.
The dielectric multilayer film 2 has large ripples, but almost no light leakage occurs at wavelengths of 780 nm and above.

<Example 3-1: Optical characteristics of optical filters>
The dielectric multilayer film 1 of Example 2-1 was laminated on the main surface of a glass substrate (alkali glass, D263 manufactured by Schott). The resin film of Example 1-1 was formed on the other main surface of the glass substrate by spin coating, and a dielectric multilayer film (anti-reflection film) in which _SiO2 and _TiO2 were alternately laminated was formed on the resin film by vapor deposition, thereby producing an optical filter 1.

<Example 3-2: Optical characteristics of optical filters>
An optical filter 2 was produced in the same manner as in Example 3-1, except that the dielectric multilayer film 2 of Example 2-2 was laminated in place of the dielectric multilayer film 1 of Example 2-1.

<Example 3-3: Optical characteristics of optical filter>
An optical filter 3 was produced in the same manner as in Example 3-1, except that the resin film of Example 1-5 was formed instead of the resin film of Example 1-1.

The optical characteristics of the optical filters 1 to 3 are shown in the table below.
Example 3-1 is an embodiment, and Examples 3-2 and 3-3 are comparative examples.

The optical filter of Example 3-1 had high visible light transmittance, small ripples at a high incident angle of 40 degrees, and was able to block light in the long wavelength region including the near infrared region of 750 to 1000 nm.
In the optical filter of Example 3-2, the dielectric multilayer film had a large incidence angle dependency, and low ripples could not be achieved at a high incidence angle of 40 degrees.
In the optical filter of Example 3-3, the visible light transmittance was significantly reduced due to excessive absorption by the dye.

The optical filter of the present invention has excellent visible light transmittance and good near-infrared light shielding properties with suppressed changes in near-infrared light shielding properties at high angles of incidence. It is useful for applications in information acquisition devices such as cameras and sensors for transport aircraft, which have become increasingly high-performance in recent years.

1A, 1B, 1C, 1D...optical filter, 10...substrate, 11...support, 12...resin film, 30...dielectric multilayer film

Claims (10)

An optical filter comprising a substrate and a dielectric multilayer film laminated as an outermost layer on at least one main surface side of the substrate,
the substrate has a resin film containing a dye (IR) and a resin;
The optical filter satisfies all of the following optical properties (i-1) to ( i-10).
(i-1) On at least one surface of the optical filter, the average reflectance R _{450-500 (5 deg) AVE} at a wavelength of 450 to 500 nm and an incident angle of 5 degrees is 3% or less, and the average reflectance R _{450-500 (40 deg) AVE} at an incident angle of 40 degrees is 5% or less. (i-2) On at least one surface of the optical filter, the average reflectance R _{500-580 (5 deg) AVE} at a wavelength of 500 to 580 nm and an incident angle of 5 degrees is 2.5% or less, and the average reflectance R _{500-580 (40 deg) AVE} at an incident angle of 40 degrees is 4% or less.
(i-3) At least one surface of the optical filter satisfies the relationships R _{450-500 (5 deg) AVE} > R _{500-580 (5 deg) AVE} and R _{450-500 (40 deg) AVE} > R _{500-580 (40 deg) AVE} .
(i-4) On at least one surface of the optical filter, the maximum reflectance R _{450-580 (5 deg) MAX} at a wavelength of 450 to 580 nm and an incident angle of 5 degrees is 4% or less, and the maximum reflectance R _{450-580 (40 deg) MAX} at an incident angle of 40 degrees is 6% or less.
(i-5) At wavelengths of 450 to 500 nm, the maximum difference between the transmittance at an incident angle of 0 degrees and the transmittance at an incident angle of 40 degrees is 6% or less. (i-6) At wavelengths of 500 to 580 nm, the maximum difference between the transmittance at an incident angle of 0 degrees and the transmittance at an incident angle of 40 degrees is 5% or less. (i-7) At wavelengths of 450 to 580 nm, the average transmittance T _{450-580 (0 deg) AVE} at an incident angle of 0 degrees is 88% or more. (i-8) At wavelengths of 600 to 800 nm, the absolute value of the difference between the wavelength at which the transmittance is 20% at an incident angle of 0 degrees and the wavelength at which the transmittance is 20% at an incident angle of 40 degrees is 10 nm or less. (i-9) At wavelengths of 600 to 800 nm, the wavelength at which the transmittance is 20% at an incident angle of 0 degrees is in the range of 640 to 690 nm. (i-10) At wavelengths of 750 to 1000 nm, the maximum transmittance T at an incident angle of 0 degrees _{750-1000 (0 deg) MAX} is 1% or less, and the maximum transmittance T at an incident angle of 40 degrees _{750-1000 (40 deg) MAX} is 1% or less 2. The optical filter according to claim 1 , wherein the resin film satisfies all of the following optical properties (ii-1) to (ii-6):
(ii-1) Average internal transmittance T _{450-580 AVE} at wavelengths of 450 to 580 nm is 88% or more; (ii-2) At wavelengths of 600 to 700 nm, the wavelength at which the internal transmittance is 20% is in the range of 640 to 690 nm; (ii-3) Internal transmittance T ₇₀₀ at a wavelength of 700 nm is 1% or less; (ii-4) Internal transmittance T ₇₅₀ at a wavelength of 750 nm is 10% or less; (ii-5) Internal transmittance T ₈₀₀ at a wavelength of 800 nm is 20% or less; (ii-6) Internal transmittance T ₉₅₀ at a wavelength of 950 nm is 60% or more and 95% or less. 3. The optical filter according to claim 1, wherein the dielectric multilayer film satisfies all of the following optical properties (iv-1) to (iv-8):
(iv-1) At a wavelength of 450 to 580 nm, the average transmittance T _{450-580 (0 deg) AVE} at an incident angle of 0 degrees is 90% or more, and the average transmittance T _{450-580 (40 deg) AVE} at an incident angle of 40 degrees is 90% or more. (iv-2) At a wavelength of 450 to 500 nm, the absolute value of the difference between the average transmittance at an incident angle of 0 degrees and the average transmittance at an incident angle of 40 degrees is 3% or less. (iv-3) At a wavelength of 500 to 580 nm, the absolute value of the difference between the average transmittance at an incident angle of 0 degrees and the average transmittance at an incident angle of 40 degrees is 2% or less. (iv-4) At a wavelength of 450 to 500 nm, the absolute value of the difference between the average transmittance at an incident angle of 0 degrees and the average transmittance at an incident angle of 40 degrees is 2% or less. (iv-5) At a wavelength of 500 to 580 nm, the maximum difference between the transmittance at an incident angle of 0 degrees and the transmittance at an incident angle of 40 degrees is 5% or less. (iv-6) At a wavelength of 600 to 800 nm, the wavelength at which the transmittance at an incident angle of 0 degrees is 20% is in the range of 720 to 770 nm. (iv-7) At a wavelength of 780 to 850 nm, the maximum transmittance T _{780-850 (0 deg) MAX} at an incident angle of 0 degrees is 4% or more and less than 10%. (iv-8) At a wavelength of 900 to 980 nm, the maximum transmittance T _{900-980 (40 deg) MAX} at an incident angle of 40 degrees is 1% or more and less than 5%. The dye (IR) is
A compound (A) having a maximum absorption wavelength in dichloromethane at a wavelength of 690 nm or more and less than 735 nm;
A compound (B) having a maximum absorption wavelength in dichloromethane at a wavelength of 735 nm or more and less than 835 nm;
4. The optical filter according to claim 1, comprising at least one compound selected from the group consisting of compounds (C) having a maximum absorption wavelength in dichloromethane in the range of 900 nm to 1000 nm. 5. The optical filter according to claim 4 , wherein the maximum difference between the maximum absorption wavelength of said compound (A) and the maximum absorption wavelength of said compound (B) is 40 nm or more. The optical filter according to any one of claims 1 to 5, wherein the dye (IR) satisfies the following characteristic (iii-1) in a spectral internal transmittance curve measured by dissolving the dye (IR) in a resin constituting the resin film such that the internal transmittance at a maximum absorption wavelength in the resin is 10%.
(iii-1) When the maximum absorption wavelength in the resin is D [nm] and the average internal transmittance in the range of 450 to 580 nm is E, E>100-(D/100). 5. The optical filter according to claim 4, wherein the compound (A) is at least one selected from either a squarylium compound or a cyanine compound, the compound (B) is at least one selected from either a squarylium compound or a cyanine compound, and the compound (C) is at least one selected from either a squarylium compound, a cyanine compound, and an immonium compound. 8. The optical filter according to claim 1 , wherein the base material includes a support and the resin film, and the resin film is laminated on at least one main surface of the support. The optical filter according to any one of claims 1 to 8 , wherein the resin is a polyimide resin. An information acquisition device comprising the optical filter according to any one of claims 1 to 9.

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