Optical Filters

Abstract

The present invention relates to an optical filter comprising a substrate and a dielectric multilayer film layered as an outermost layer on at least one main surface of the substrate, wherein the substrate includes a resin film containing a resin and a pigment (A) having a maximum absorbance wavelength at 730-800 nm in dichloromethane, and the pigment (A) satisfies specific spectral characteristics in the resin.

Description

[Technical field]

[0001] The present invention relates to an optical filter that transmits light in the visible wavelength region and blocks light in the near-infrared wavelength region. [Background technology]

[0002] 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 wavelength range (hereinafter also referred to as "near-infrared light").

[0003] Such optical filters include various types, such as a reflective filter in which dielectric thin films with different refractive indices are alternately laminated (dielectric multilayer film) on one or both sides of a transparent substrate, and the optical interference is utilized to reflect light to be blocked. Since the optical thickness of the dielectric multilayer film changes depending on the angle of incidence of light, problems include changes in the spectral transmittance curve depending on the angle of incidence, light leakage in which near-infrared light that should have a high reflectance at a high angle of incidence has a high transmittance, and noise due to near-infrared light reflected by the dielectric multilayer film. If such a filter is used, the spectral sensitivity of the solid-state imaging element may be affected by the angle of incidence. Therefore, there has been a demand for an optical filter that blocks near-infrared light without substantially affecting the transmittance of visible light and without depending on the angle of incidence.

[0004] Here, Patent Documents 1 to 3 describe optical filters that include a layer containing a near-infrared absorbing dye in order to reduce the incidence angle dependency. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 022069 [Patent Document 2] International Publication No. 2019 / 168090 [Patent Document 3] Japanese Patent Application Publication No. 2019-164269 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the optical filter described in Patent Document 1 has room for improvement in terms of near-infrared light blocking properties, and the optical filters described in Patent Documents 2 and 3 have room for improvement in terms of visible light transmittance. Therefore, an object of the present invention is to provide an optical filter that maintains high transmittance of visible light while suppressing deterioration in near-infrared light shielding properties at high angles of incidence, such as light leakage, in near-infrared light shielding properties. [Means for solving the problem]

[0007] 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 includes a resin film containing a dye (A) having a maximum absorption wavelength in dichloromethane of 730 to 800 nm and a resin; The dye (A) is dissolved in the resin so that the transmittance at the maximum absorption wavelength is 10%, and the resulting coating film is coated on an alkali glass plate. In this coating film, the dye (A) satisfies all of the following spectral characteristics (i-1) to (i-3) in the spectral transmittance curve. (i-1) Average internal transmittance T in the spectral transmittance curve with wavelengths of 430 to 460 nm 430-460(AVE) More than 95% (i-2) Average internal transmittance T in the spectral transmittance curve with wavelengths of 460 to 530 nm 460-530(AVE) More than 97% (i-3) The absolute value of the difference between the shortest wavelength and the second shortest wavelength at which the internal transmittance is 50% at wavelengths of 600 nm or more is 125 nm or more. Effect of the Invention

[0008] According to the present invention, it is possible to provide an optical filter that has high transmittance for visible light and suppresses a decrease in the blocking ability for near-infrared light at a high angle of incidence. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view illustrating an example of an optical filter according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view illustrating a schematic configuration of another example of the optical filter according to the embodiment. [Diagram 3] FIG. 3 is a cross-sectional view illustrating a schematic configuration of another example of the optical filter according to the embodiment. [Figure 4] FIG. 4 is a cross-sectional view illustrating a schematic configuration of another example of the optical filter according to the embodiment. [Diagram 5] FIG. 5 is a diagram showing the spectral transmittance curves of the resin films of Examples 2-1, 2-7, and 2-12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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 made 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.

[0011] 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 {actually measured transmittance / (100-reflectance)}×100. In this specification, the transmittance of a substrate and the transmittance of a resin film including a case where a dye is contained in the resin are all "internal transmittance" even when they are described 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 actually measured transmittances.

[0012] 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. In this specification, the term "to" indicating a numerical range includes the upper and lower limits.

[0013] <Optical filters> An optical filter according to one embodiment of the present invention (hereinafter also referred to as "the present filter") includes a substrate and a dielectric multilayer film laminated as an outermost layer on at least one main surface side of the substrate.

[0014] 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 diagrammatically show an example of an optical filter according to an embodiment. 1 is an example 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.

[0015] 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.

[0016] 3 is an example in which a substrate 10 has a support 11 and a resin film 12 laminated on one main surface 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.

[0017] 4 is an example in which a 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.

[0018] <Base material> In the optical filter of the present invention, the substrate includes a resin film containing a dye (A) having a maximum absorption wavelength in dichloromethane at 730 to 800 nm and a resin. The dye (A) is a near-infrared absorbing (NIR) dye. By providing a substrate including a resin film containing a near-infrared absorbing dye, it is possible to suppress the degradation of the spectral characteristics of the dielectric multilayer film at high angles of incidence, for example, the occurrence of light leakage and noise in the near-infrared region, due to the absorption characteristics of the substrate.

[0019] <Dye (A)> The dye (A) satisfies specific spectral characteristics in the resin used for the substrate. Specifically, the dye (A) is dissolved in the resin so that the transmittance at the maximum absorption wavelength is 10%, and the coating film is coated on an alkali glass plate. In the spectral transmittance curve, the dye (A) satisfies all of the following spectral characteristics (i-1) to (i-3): (i-1) Average internal transmittance T in the spectral transmittance curve with wavelengths of 430 to 460 nm 430-460(AVE) More than 95% (i-2) Average internal transmittance T in the spectral transmittance curve with wavelengths of 460 to 530 nm 460-530(AVE) More than 97% (i-3) The absolute value of the difference between the shortest wavelength and the second shortest wavelength at which the internal transmittance is 50% at wavelengths of 600 nm or more is 125 nm or more.

[0020] The present filter containing the dye (A) that satisfies all of the above-mentioned spectral characteristics is an optical filter that has high visible light transmittance and, by absorbing a wide range of near-infrared light, suppresses the decrease in the near-infrared light blocking ability at high angles of incidence.

[0021] By satisfying the spectral characteristic (i-1), an optical filter having excellent transmittance of visible light, particularly blue light, can be obtained. The spectral characteristic (i-1) is preferably 96% or more.

[0022] By satisfying the spectral characteristic (i-2), an optical filter having excellent transmittance of visible light, particularly green light, can be obtained. The spectral characteristic (i-2) is preferably 98% or more.

[0023] By satisfying the spectral characteristic (i-3), an optical filter capable of absorbing near-infrared light broadly over a wide wavelength range can be obtained. This makes it possible to efficiently prevent light leakage in wavelength bands where dielectric multilayer films are unable to completely block light at high angles of incidence and light leakage is likely to occur. In order to absorb light over a wide wavelength range, it is possible to combine multiple types of dyes with different maximum absorption wavelengths. However, when multiple types of NIR dyes are combined, while it is possible to block a wide range of light in the near-infrared region, the transmittance in the visible light region also tends to decrease at the same time. Since the dye (A) itself exhibits broad absorption characteristics in the resin, it is possible to efficiently block light in the near-infrared region using only the dye (A) while maintaining good transmittance in the visible light region, without combining multiple types of NIR dyes. The absolute value of the spectral characteristic (i-3) is preferably 128 nm or more, and more preferably 130 nm or more.

[0024] Examples of the dye (A) include cyanine dyes, squarylium dyes, phthalocyanine dyes, immonium dyes, and diimmonium dyes, and cyanine dyes are preferred because they tend to satisfy the above-mentioned spectral properties (i-1) to (i-3).

[0025] As the cyanine dye, a compound represented by the following formula (A) is particularly preferred.

[0026] [ka]

[0027] Here, the symbols in formula (A) are as follows: R 1 ~R 7 are each independently a hydrogen atom, a halogen atom, a sulfo group, a hydroxyl group, a cyano group, a nitro group, a carboxy group, a phosphate group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, or an acyloxy group having 1 to 10 carbon atoms which may have a substituent. In formula (A), R 1 ~R 7 may be the same or different on the left and right sides of the formula, but it is preferable that they are all the same.

[0028] The substituent in the optionally substituted alkyl group, alkoxy group or acyloxy group having 1 to 10 carbon atoms includes a halogen atom and an alkoxy group having 1 to 10 carbon atoms.

[0029] Here, in this specification, unless otherwise specified, the alkyl group may be linear, branched, cyclic, or a combination of these structures. The same applies to the alkyl group of the alkoxy group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and the fluorine atom and the chlorine atom are preferred.

[0030] R 1 From the viewpoint of ease of synthesis, each of is preferably a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group or an acyloxy group, and particularly preferably a hydrogen atom.

[0031] R 2 ~R 7are preferably each independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, or an acyloxy group having 1 to 10 carbon atoms which may have a substituent. From the viewpoint of ease of synthesis, etc., it is preferable that these are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms which may have a substituent.

[0032] R 6 ~R 7 From the viewpoint of solubility in transparent resins and solvents, at least one of them is preferably an alkyl group having 1 to 10 carbon atoms, more preferably a secondary or tertiary branched alkyl group having 10 or less carbon atoms, and further preferably a tertiary butyl group, an isopropyl group, or an isobutyl group.

[0033] R 2 ~R 5 , R 6 ~R 7 or adjacent two may be linked to each other to form a ring having 5 to 8 members. The ring may be aliphatic or aromatic.

[0034] Formula (A) optionally has Z. Z is a 5-membered or 6-membered ring. When Z is present, it is preferable in terms of durability. The hydrogen atom bonded to the carbon atom constituting Z may be substituted with an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms.

[0035] In this specification, unless otherwise specified, an aryl group refers to a group bonded via a carbon atom constituting an aromatic ring contained in an aromatic compound, such as a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a thiophene ring, or a pyrrole ring.

[0036] X - indicates a monovalent anion. X - PF6 - , [Rf-SO2] - , [N(Rf-SO2)2] - , or BF4 -Rf represents an alkyl group substituted with at least one fluorine atom, preferably a perfluoroalkyl group having 1 to 8 carbon atoms, and particularly preferably -CF3. By having such an anion structure, a dye compound (A) having excellent light resistance can be obtained.

[0037] R 8 is a hydrogen atom, a halogen atom, or -Y 5 -R 10 (Y 5 is a single bond, an ether bond (-O-), a sulfonyl bond (-SO2-), an ester bond (-C(=O)-O- or -OC(=O)-) or a ureido bond (-NH-C(=O)-NH-), and R 10 represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms, which may have a substituent.

[0038] R 8 is a hydrogen atom, a halogen atom, Y 5 -Y is a single bond 5 -R 10 is preferred, and a hydrogen atom, a chlorine atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms which may be substituted with a halogen atom is more preferred.

[0039] More specifically, in the formula (A), the following compounds are included in which the atoms or groups bonded to each skeleton are shown in the table below. In all of the compounds shown in the table below, R 1 ~R 7 are all identical on both sides of the equation.

[0040] [Table 1]

[0041] The dye (A) is, for example, R 1 ~R 5 , R 7 is a hydrogen atom, and X - BF4 -The dye (A1) can be synthesized as shown in the synthesis scheme.

[0042] [ka]

[0043] (1) Salicylaldehyde (a) and R 6 The compound (c) is obtained by reacting an alkyne compound (b) having a group. (2) Compound (c) is reacted with 4-dimethylaminopyridine to obtain compound (d). (3) Compound (d) is reacted with methylmagnesium bromide and tetrafluoroboric acid to obtain compound (e). (4) Compound (e) is reacted with R 8 The dye (A1) is obtained by reacting with an aldehyde dianilide hydrochloride (f) having a group.

[0044] X - PF6 - In this case, hexafluorophosphoric acid can be used instead of tetrafluoroboric acid in step (3) to obtain X - [Rf-SO2] - In this case, Rf-SO3H is used instead of tetrafluoroboric acid in step (3) to obtain X - [N(Rf-SO2)2] - In this case, they can be synthesized by using NH(Rf-SO2)2 instead of tetrafluoroboric acid in step (3) above.

[0045] The resin film may contain one type of dye (A) alone or a combination of two or more types.

[0046] The content of dye (A) in the resin film is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the resin, from the viewpoints of the spectral characteristics and Tg of the resin film, and the solubility of dye (A) in the resin film.

[0047] <Dye (B)> In the present filter, it is preferable that the resin film further contains a dye (B) having a maximum absorption wavelength in dichloromethane at 650 to 730 nm. The dye (B) is also a near-infrared absorbing (NIR) dye like the dye (A). This makes it possible to more efficiently block near-infrared light.

[0048] When the resin film contains the dye (A) and the dye (B), it is preferable that the resin film satisfies all of the following spectroscopic properties (ii-1) to (ii-4).

[0049] (ii-1) When the content of the dye (A) in the resin film is [A] (mass%) and the content of the dye (B) is [B] (mass%), [A] / [B]<0.85 (ii-2) Internal transmittance T at a wavelength of 700 nm 700 Less than 5% (ii-3) Average internal transmittance T in the spectral transmittance curve with wavelengths of 730 to 800 nm 730-800(AVE) Less than 25% (ii-4) Average internal transmittance T in the spectral transmittance curve with wavelengths of 430 to 460 nm 430-460(AVE) More than 92%

[0050] By satisfying the spectral characteristic (ii-1), the dye (A) can absorb a wide range of near-infrared light, which means that even if the content of the dye (A) is small, light near the maximum absorption wavelength of the dye (A) can be sufficiently blocked. The spectral characteristic (ii-1) is more preferably [A] / [B]<0.75, and more preferably 0.05<[A] / [B].

[0051] Satisfying the spectral characteristic (ii-2) means that the film has a high degree of blocking near-infrared light. The spectral characteristic (ii-2) is more preferably 4% or less.

[0052] Satisfying the spectral characteristic (ii-3) means that the film has a high degree of blocking near-infrared light. The spectral characteristic (ii-3) is more preferably 24% or less.

[0053] Satisfying the spectral characteristic (ii-4) means that the transmittance of blue light is high. The spectral characteristic (ii-4) is more preferably 92.5% or more.

[0054] As the dye (B), at least one selected from the group consisting of squarylium dyes, cyanine dyes, phthalocyanine dyes, immonium dyes and diimmonium dyes is preferred, and squarylium dyes are particularly preferred.

[0055] The squarylium dye is preferably a compound represented by the following formula (I).

[0056] [ka]

[0057] In the formula (I), the symbols are as follows: R 24 and R 26 each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group or an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 10 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, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 11 carbon atoms, or an aryl group having 7 to 18 carbon atoms which may have a substituent and which may have an oxygen atom between the carbon atoms), -NHR 30 , or -SO2-R 30 (R 30 represents a hydrocarbon group having 1 to 25 carbon atoms, each of which may have one or more hydrogen atoms 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 , R42 each independently represents a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 10 carbon atoms. k is 2 or 3.

[0058] [ka]

[0059] 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, heterocycle B, and heterocycle C, respectively.

[0060] R when heterocycle A is formed 21 and R 22 represents a divalent group -Q- to which these are bonded, which is an alkylene group or an 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.

[0061] R when heterocycle B is formed 22 and R 25 and R when a heterocycle C is formed. 21 and R 23 are the divalent groups -X 1 -Y 1 -and-X 2 -Y 2 - (The side that is bonded to nitrogen is X 1 and X 2 ) as X 1 and X 2 are groups represented by the following formula (1x) or (2x), and Y 1 and Y 2 Each of X is a group selected from the following formulas (1y) to (5y). 1 and X 2 are groups represented by the following formula (2x), Y 1and Y 2 may each be a single bond, in which case there may be an oxygen atom between the carbon atoms.

[0062] [ka]

[0063] 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 -NR 38 R 39 (R 38 and R 39 R each independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. 31 ~R 36 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R 37 represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms.

[0064] R 27 , R 28 , R 29 , R 31 ~R 37 , R when not forming a heterocycle 21 ~R 23 , and R 25 may be bonded to any other of these to form a 5- or 6-membered ring. 31 and R 36 , R 31 and R 37 may be directly bonded.

[0065] When R does not form a heterocycle 21 and R 22 each independently represents a hydrogen atom, an alkyl group or an aryl group having 1 to 6 carbon atoms which may have a substituent, or an aryl group or an arylaryl group having 6 to 11 carbon atoms which may have a substituent. 23 and R 25each independently represents a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 6 carbon atoms.

[0066] Compound (I) can be produced by known methods, for example, as described in U.S. Pat. No. 5,543,086, U.S. Patent Application Publication No. 2014 / 0061505, and WO 2014 / 088063.

[0067] The resin film may contain one type of dye (B) alone or a combination of two or more types.

[0068] The content of the dye (B) in the resin film is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the resin.

[0069] <Other dyes> The resin film may contain other dyes, such as UV dyes, in addition to the NIR dye. Specific examples of UV dyes 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. The UV dyes may be used alone or in combination of two or more kinds.

[0070] <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, the substrate is preferably a resin substrate made of a resin film containing a resin and an NIR dye (A). When the substrate has a multi-layer structure, it is preferably a composite substrate having a resin film containing the NIR dye (A) laminated on at least one main surface of the support, in which case the support is preferably made of a transparent resin or a transparent inorganic material.

[0071] 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 spectral characteristics, 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.

[0072] When the substrate contains the NIR dye (B) or other dyes, these dyes may be contained in the resin film containing the NIR dye (A) or in a separate resin film.

[0073] As the transparent inorganic material, glass or a crystalline material is preferable. Examples of glass that can be used for the support include absorbing glass (near-infrared absorbing glass) containing copper ions in phosphate glass or phosphate glass, soda-lime glass, borosilicate glass, alkali-free glass, and quartz glass. As for glass, absorbing glass is preferable depending on the purpose, and phosphate glass and phosphate glass are preferable from the viewpoint of absorbing infrared light. When it is desired to capture a large amount of red light (600 to 700 nm), alkali glass, alkali-free glass, and quartz glass are preferable. Note that "phosphate glass" also includes silicophosphate glass, in which part of the glass skeleton is composed of SiO2.

[0074] The glass to be used may be chemically strengthened glass obtained by exchanging alkali metal ions having a small ionic radius (e.g., Li ions, Na ions) present on the main surface of the glass sheet with alkali ions having 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 equal to or lower than the glass transition point.

[0075] Examples of crystalline materials that can be used for the support include birefringent crystals such as quartz, lithium niobate, and sapphire.

[0076] As the support, from the viewpoint of shape stability related to long-term reliability of optical properties, mechanical properties, etc., and handling properties during filter production, inorganic materials are preferred, and glass and sapphire are particularly preferred.

[0077] The resin film can be formed by dissolving or dispersing the dye (A), 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 the coating liquid to a support, drying it, and further curing it as necessary. The support may be the support included in the present filter, or may be a peelable support used only when forming the resin film. The solvent may be a dispersion medium that can be stably dispersed or a solvent that can dissolve the material.

[0078] The coating liquid may also contain a surfactant to improve voids caused by microbubbles, depressions caused by the adhesion of foreign matter, and repellency during the drying process. For example, a dip coating method, a cast coating method, or a spin coating method can be used for coating the coating liquid. After the coating liquid is applied onto a support, a resin film is formed by drying. When the coating liquid contains raw materials for a transparent resin, a curing process such as heat curing or light curing is further performed.

[0079] The resin film can also be produced in the form of a film by extrusion molding. When the substrate is a single-layer structure (resin substrate) made of a resin film containing the dye (A), the resin film can 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 the dye (A) laminated on at least one main surface of the support, the substrate can be produced by laminating this film on the support and integrating them by thermocompression or the like.

[0080] The optical filter may have one or more resin layers in it. When the optical filter has two or more resin layers, the layers may have the same or different configurations.

[0081] The thickness of the resin film is preferably 0.3 to 20 μm. The optical filter of the present invention can block near infrared light over a wide range efficiently even with a small dye content by containing an NIR dye (A) that satisfies specific spectral characteristics in the resin. This allows the resin film containing the dye (A) to be thin. When the resin film is made of multiple layers, the total thickness of the layers is preferably 0.6 to 40 μm. When the substrate has a single layer structure (resin substrate) made of a resin film containing the dye (A), the thickness of the resin film is preferably 50 to 150 μm. When the substrate has a multilayer structure (composite substrate) having a support and a resin film containing dye (A) laminated on at least one main surface of the support, the thickness of the resin film is preferably 0.3 to 20 μm.

[0082] 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, and when the substrate is a composite substrate comprising a support and a resin film, the thickness is preferably 100 to 300 μm.

[0083] <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.

[0084] 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 a NIR reflective layer), and the other of the dielectric multilayer films is preferably designed as a NIR reflective layer, a reflective layer having a reflection range other than the near-infrared range, or an anti-reflection layer.

[0085] The NIR reflective layer is a dielectric multilayer film designed to block light in the near infrared region. The NIR reflective layer has wavelength selectivity that transmits visible light and mainly reflects light in the near infrared region other than the light blocking region of the resin film that is the absorption layer. The reflection region of the NIR reflective layer may include the light blocking region in the near infrared region 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 regions other than the near infrared region, for example, the near ultraviolet region.

[0086] The NIR reflective layer is composed of, for example, 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 Ta2O5, TiO2, and Nb2O5. Among these, TiO2 is preferred in terms of film formability, reproducibility in refractive index, etc., stability, etc.

[0087] 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 the material for the low refractive index film include SiO2, SiO x N y From the viewpoints of reproducibility, stability, economy, etc. in film formation, SiO2 is preferred.

[0088] The NIR reflective layer is preferably designed so as to satisfy all of the following conditions (iv-1) to (iv-4) in the spectral transmittance curves at incidence angles of 0 degrees and 30 degrees. (iv-1) The wavelength at which the transmittance is 50% is in the wavelength range of 600 to 850 nm (iv-2) The wavelength at which the transmittance is 50% is in the wavelength range of 385 to 425 nm. (iv-3) The average transmittance of light in the wavelength range of 435 to 650 nm is 88% or more. (iv-4) The average transmittance of light in the wavelength range of 750 to 1000 nm is 10% or less.

[0089] Furthermore, it is preferable that the NIR reflective layer has a steep change in transmittance in the boundary wavelength region between the transmission region and the light blocking region. For this purpose, the total number of laminated layers of the dielectric multilayer film constituting the reflective layer is preferably 15 layers or more, more preferably 25 layers or more, and even more preferably 30 layers or more. However, since warping or an increase in film thickness occurs when the total number of laminated layers is large, the total number of laminated layers is preferably 100 layers or less, more preferably 75 layers or less, and even more preferably 60 layers or less. Moreover, the film thickness of the reflective layer is preferably 2 to 10 μm overall.

[0090] If the total number of layers and the thickness of the dielectric multilayer film are within the above ranges, the NIR reflective layer satisfies the requirement for miniaturization and can suppress the incidence angle dependency while maintaining high productivity. In addition, the dielectric multilayer film can be formed by, for example, a vacuum film formation process such as a CVD method, a sputtering method, or a vacuum deposition method, or a wet film formation process such as a spray method or a dip method.

[0091] The NIR reflective layer may have a single layer (a group of dielectric multilayer films) that provides a predetermined optical characteristic, or may have two layers that provide a predetermined optical characteristic. 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 a plurality of reflective layers with different reflection bands. 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.

[0092] Examples of the antireflection layer include a dielectric multilayer film, an intermediate refractive index medium, and a moth-eye structure in which the refractive index changes gradually. Among these, a dielectric multilayer film is preferred from the viewpoints of optical efficiency and productivity. The antireflection layer is obtained by alternately laminating dielectric films in the same manner as the reflective layer.

[0093] <Optical filters> It is preferable that the optical filter of the present invention, having the above-mentioned configuration, satisfies all of the following spectral characteristics (iii-1) to (iii-3). (iii-1) Maximum transmittance T in the spectral transmittance curve with a wavelength of 730 to 800 nm and an incident angle of 60 degrees 730-800(60°)(MAX) is 1.5% or less (iii-2) Average transmittance T in the spectral transmittance curve with wavelengths of 435 to 480 nm and an incident angle of 0 degrees 435-480(0°)(AVE) More than 85% (iii-3) Average transmittance T in the spectral transmittance curve with wavelengths of 435 to 480 nm and an incident angle of 30 degrees 435-480(30°)(AVE) More than 85%

[0094] By satisfying the spectral characteristic (iii-1), an optical filter that does not lose light even when the light is incident at a high angle and has high near-infrared light blocking properties can be obtained. The spectral characteristic (iii-1) is more preferably 1.0% or less.

[0095] By satisfying the spectral characteristic (iii-2), an optical filter having excellent transmittance for blue light can be obtained. The spectral characteristic (iii-2) is more preferably 89% or more.

[0096] By satisfying the spectral characteristic (iii-3), an optical filter having excellent transmittance for blue light even at a high angle of incidence can be obtained. The spectral characteristic (iii-3) is more preferably 89% or more. The filter may also include other components (layers) that absorb light using inorganic particles that control the transmission and absorption of light in a specific wavelength range. Specific examples of inorganic particles include ITO (indium tin oxide), ATO (antimony-doped tin oxide), cesium tungstate, lanthanum boride, etc. ITO particles and cesium tungstate particles have high visible light transmittance and light absorption over a wide range of infrared wavelengths exceeding 1200 nm, and therefore can be used when such infrared light shielding is required.

[0097] When the present filter is used in an imaging device such as a digital still camera, the imaging device can provide an imaging device with excellent color reproducibility. An imaging device using the present filter includes a solid-state imaging element, an imaging lens, and the present filter. The present filter can be used, for example, by being disposed 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. EXAMPLES

[0098] 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). Unless the angle of incidence is specifically stated, the spectral characteristics are values ​​measured at an angle of incidence of 0 degrees (perpendicular to the principal surface of the optical filter).

[0099] The dyes used in each example are as follows: Compounds 1, 2, and 3: Synthesized by the method described below. Compound 4: Synthesized based on Dyes and pigments 73 (2007) 344-352. Compound 5: Synthesized based on WO 2019 / 168090. Compound 6: FEW Chemicals, product name S2137 Compound 7: Synthesized based on JP 2019-164269 A. Compound 8: Phthalocyanine manufactured by Yamada Chemical Co., Ltd. Product name: FDR-026 Compound 9: Synthesized based on WO 2017 / 135359. Compound 10: Synthesized based on Japanese Patent No. 6358114. Compound 11: Synthesized based on U.S. Patent Application Publication No. 2014 / 0061505 and WO 2014 / 088063. Compound 12: Synthesized according to the specification of US Pat. No. 5,543,086.

[0100] [ka]

[0101] [ka]

[0102] [ka]

[0103] <Synthesis of Compound 1>

[0104] [ka]

[0105] <Step 1> 3,3-Dimethyl-1-butyne (13g, 160mmol) and tetrahydrofuran (40mL) were placed in a 1L eggplant flask, cooled to -78°C and stirred, and n-butyllithium (1.6M in n-hexane, 100mL) was added dropwise and stirred at -78°C for one hour. Then, salicylaldehyde (10g, 82mmol) dissolved in tetrahydrofuran (80mL) was added and stirred at room temperature for three hours. After the reaction was completed, the reaction was quenched by adding a saturated aqueous ammonium chloride solution and extracted with ethyl acetate. After removing the solvent, manganese dioxide (35g, 400mmol) and acetone (80mL) were added and stirred at room temperature for 16 hours. After the reaction was completed, a filtration operation was performed, and the solvent of the filtrate was removed, followed by purification by column chromatography to obtain 6.1g (37%) of intermediate (c1). <Step 2> Intermediate (c1) (6.1 g, 30 mmol) and N,N-dimethylformamide (120 mL) were placed in a 500 mL recovery flask, cooled to 0°C and stirred, 4-dimethylaminopyridine (0.37 g, 3.0 mmol) was added, and the reaction was allowed to proceed at room temperature for 16 hours. After the reaction was completed, water was added to quench the reaction, and the mixture was extracted with ethyl acetate. The solvent was removed, and the mixture was purified by column chromatography to obtain 4.2 g (70%) of intermediate (d1). <Step 3> Intermediate 2 (4.2 g, 21 mmol) and tetrahydrofuran (50 mL) were placed in a 500 mL eggplant flask, cooled to 0°C and stirred, methylmagnesium bromide (1 M in tetrahydrofuran, 30 mL) was added dropwise, and the reaction was allowed to proceed at room temperature for 5 hours. After the reaction was completed, ice water was added to quench the reaction, and 42% aqueous tetrafluoroboric acid solution (150 mL) was added and the reaction was allowed to proceed at room temperature for 30 minutes. After extraction with dichloromethane and removal of the solvent, the precipitated solid was washed with ethyl acetate to obtain 4.4 g (77%) of intermediate (e1). <Step 4> In a 500 mL eggplant flask, intermediate (e1) (4.4 g, 15 mmol), malonaldehyde dianilide hydrochloride (1.9 g, 7.5 mmol), sodium acetate (3.0 g, 36 mmol), acetic acid (60 mL), and acetic anhydride (60 mL) were placed and stirred at 80 degrees for 2 hours. After the reaction was completed, water was added and the precipitated solid was collected by filtration and purified by column chromatography to obtain 1.9 g (50%) of compound 1.

[0106] <Synthesis of compound 2>

[0107] [ka]

[0108] <Step 1> Intermediate (d1) (5.0 g, 25 mmol) obtained by the same synthesis method as compound 1 was placed in a 500 mL eggplant flask, tetrahydrofuran (60 mL) was added, and the mixture was cooled to 0 degrees and stirred. Methyl magnesium bromide (1 M in tetrahydrofuran, 37 mL) was added dropwise and reacted at room temperature for 5 hours. After the reaction was completed, ice water was added to quench the reaction, and 60% hexanefluorophosphoric acid aqueous solution (150 mL) was added and stirred at room temperature for 30 minutes. After extraction with dichloromethane and removal of the solvent, the precipitated solid was washed with ethyl acetate to obtain 7.2 g (84%) of intermediate (e2). <Step 2> In a 500 mL eggplant flask, intermediate (e2) (5.2 g, 15 mmol), malonaldehyde dianilide hydrochloride (1.9 g, 7.5 mmol), sodium acetate (3.0 g, 36 mmol), acetic acid (60 mL), and acetic anhydride (60 mL) were placed and stirred at 80 degrees for 2 hours. After the reaction was completed, water was added and the precipitated solid was collected by filtration and purified by column chromatography to obtain 1.8 g (41%) of compound 2.

[0109] <Synthesis of compound 3>

[0110] [ka]

[0111] <Step 1> Intermediate (d1) (3.0 g, 15 mmol) obtained by the same synthesis method as compound 1 was placed in a 500 mL eggplant flask, tetrahydrofuran (36 mL) was added, and the mixture was cooled to 0 degrees and stirred. Methyl magnesium bromide (1 M in tetrahydrofuran, 22 mL) was added dropwise and reacted at room temperature for 5 hours. After the reaction was completed, ice water was added to quench the reaction, and a 10% aqueous solution of bis(trifluoromethanesulfonyl)imide (100 mL) was added and stirred at room temperature for 30 minutes. After extraction with dichloromethane and removal of the solvent, the precipitated solid was washed with ethyl acetate to obtain 5.3 g (75%) of intermediate (e3). <Step 2> In a 500 mL eggplant flask, intermediate (e3) (5.3 g, 11 mmol), malonaldehyde dianilide hydrochloride (1.4 g, 5.3 mmol), sodium acetate (2.1 g, 26 mmol), acetic acid (50 mL), and acetic anhydride (50 mL) were placed and stirred at 80 degrees for 2 hours. After the reaction was completed, water was added and the precipitated solid was collected by filtration and purified by column chromatography to obtain 1.6 g (42%) of compound 3.

[0112] <Spectral characteristics of dye (A) in resin> <Examples 1-1 to 1-10> 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, an NIR dye compound shown in the table below 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, Shotto D263) and dried to obtain a resin film (coated film) with a thickness of 1 μm. Using the spectral transmittance curve and the spectral reflectance curve of this resin-film-coated glass substrate, a spectral internal transmittance curve was calculated and normalized so that the internal transmittance at the maximum absorption wavelength was 10%. The spectral characteristics are shown in the table below. Examples 1-1 to 1-3 are working examples, and Examples 1-4 to 1-10 are comparative examples.

[0113] 50%-50% absorption width: The absolute value (nm) of the difference between the shortest and second shortest wavelengths at which the internal transmittance is 50% for wavelengths 600 nm or greater

[0114] [Table 2]

[0115] As shown in Examples 1-1 to 1-3, compared with Compounds 4 to 10, Compounds 1 to 3 exhibited a wide range of near-infrared light absorption characteristics while maintaining high transmittance of blue and green light in the spectrum in the resin.

[0116] <Spectral characteristics of resin film> <Examples 2-1 to 2-12> Polyimide resin (Mitsubishi Gas Chemical C-3G30G) was dissolved in an organic solvent (cyclohexanone: gamma-butyrolactone = 1:1 mass ratio) at a concentration of 8.5 mass%. NIR dye (A) and NIR dye (B) shown in the table below were added to this resin solution in the amounts (parts by mass) shown in the table below per 100 parts by mass of 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, Shotto D263) and dried to obtain a resin film with a thickness of 1 μm. Using the spectral transmittance curve and the spectral reflectance curve of this resin-film-coated glass substrate, a spectral internal transmittance curve was calculated and normalized so that the internal transmittance at the maximum absorption wavelength was 10%. The spectral characteristics are shown in the table below. FIG. 5 shows the spectral transmittance curves of the resin films of Examples 2-1, 2-7, and 2-12. Examples 2-1 to 2-4 are working examples, and Examples 2-5 to 2-12 are comparative examples.

[0117] [Table 3]

[0118] As shown in Examples 1-1 to 1-3, the resin films of Examples 2-1 to 2-4, which use NIR dye compounds 1 to 3 having excellent spectral characteristics in the resin, have excellent spectral characteristics, i.e., excellent blue light transmittance and excellent near-infrared light blocking properties, even with a small dye content.

[0119] <Manufacturing of dielectric multilayer films> We designed a reflective layer consisting of 42 layers of dielectric multilayer film, in which TiO2 and SiO2 films are alternately laminated. The reflective layer was designed to satisfy the following conditions for the spectral transmittance curves at incidence angles of 0 degrees and 30 degrees by simulating the number of layers in the dielectric multilayer film, the thickness of the TiO2 film, and the thickness of the SiO2 film as parameters. (iv-1) The wavelength at which the transmittance is 50% is in the wavelength range of 600 to 850 nm (iv-2) The wavelength at which the transmittance is 50% is in the wavelength range of 385 to 425 nm. (iv-3) The average transmittance of light in the wavelength range of 435 to 650 nm is 88% or more. (iv-4) The average transmittance of light in the wavelength range of 750 to 1000 nm is 10% or less. The optical properties of the resulting reflective layer are shown in the table below.

[0120] [Table 4]

[0121] <Spectral characteristics of optical filters> <Example 3-1> The internal transmittance of the resin film obtained in Example 2-1 and the transmittance of the reflective layer made of the above-mentioned dielectric multilayer film were multiplied at each wavelength in the wavelength range of 350 to 1200 nm to estimate the spectral characteristics of an optical filter in which a resin film is formed on one main surface of a glass substrate and a reflective layer is formed on the other main surface.

[0122] <Example 3-2> The spectral characteristics of the optical filter were estimated in the same manner as in Example 3-1, except that the resin film was changed to the resin film obtained in Example 2-7.

[0123] <Example 3-3> The spectral characteristics of the optical filter were estimated in the same manner as in Example 3-1, except that the resin film was changed to the resin film obtained in Example 2-12.

[0124] The spectral characteristics are shown in the table below. It should be noted that Example 3-1 is an embodiment, and Examples 3-2 and 3-3 are comparative examples.

[0125] [Table 5]

[0126] The optical filter of Example 3-1 has a resin film using Compound 1, which exhibits a wide range of near-infrared light absorption characteristics while maintaining high transmittance of blue light and green light in the spectrum in the resin, and thus has high visible light transmittance and suppresses the decrease in the near-infrared light shielding ability at a high incident angle. The optical filter of Example 3-2 resulted in a low transmittance of visible light. The optical filter of Example 3-3 did not contain an NIR dye exhibiting a wide range of near-infrared light absorption characteristics, and light leakage occurred at high incident angles, resulting in a decrease in the near-infrared light shielding properties.

[0127] <Light resistance test> <Examples 4-1 to 4-2> Using each compound shown in the table below, a glass substrate with a resin film was produced in the same manner as in Example 1-1 (spectral properties of dye (A) in resin) described above. A reflective layer consisting of 42 dielectric multilayer films was formed by alternately laminating TiO2 layers and SiO2 layers on the surface of the resin film that was not in contact with the glass plate, and a light resistance test sample was prepared. In the light resistance test, a Super Xenon Weather Meter SX75 (product name, manufactured by Suga Test Instruments Co., Ltd.) was used to irradiate light onto the dielectric multilayer film surface of the sample under the following conditions. Wavelength: 300~400nm Temperature: 40℃ Humidity: 50%RT Accumulated light output: 6.0kw / hour / m 2 Before and after irradiation, the spectral transmittance curve was measured, and the dye remaining rate was calculated according to the following formula. Dye remaining rate [%] = [absorbance at maximum absorption wavelength after irradiation / absorbance at maximum absorption wavelength before irradiation] x 100 The criterion for judgment was that a pigment remaining rate of 70% or more was considered to be excellent in light resistance. The results are shown in the table below. It should be noted that Example 4-1 is an embodiment, and Example 4-2 is a comparative example.

[0128] [Table 6]

[0129] From the above results, it is understood that when Compound 1, which exhibits excellent spectral characteristics in a resin, is used, the light resistance is also excellent.

[0130] Although the present invention has been described in detail and with reference to specific embodiments, it is 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. 2020-128622) filed on July 29, 2020, the contents of which are incorporated herein by reference. [Industrial Applicability]

[0131] The optical filter of the present invention has good near-infrared light shielding properties, in which the near-infrared light shielding property is suppressed from decreasing particularly at a high incidence angle, while maintaining good near-infrared light shielding properties and visible light transmittance, particularly blue light transmittance, and 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. [Explanation of symbols]

[0132] 1A, 1B, 1C, 1D...optical filter, 10...substrate, 11...support, 12...resin film, 30...dielectric multilayer film

Claims

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 includes a resin film containing a dye (A) having a maximum absorption wavelength in dichloromethane at 730 to 800 nm and a resin; the dye (A) satisfies all of the following spectral characteristics (i-1) to (i-3) in a spectral transmittance curve of a coating film obtained by dissolving the dye (A) in the resin and coating the resulting solution on an alkali glass plate so that the transmittance at the maximum absorption wavelength is 10%, The optical filter, wherein the dye (A) is a compound represented by the following formula (A): (i-1) Average internal transmittance T in the spectral transmittance curve for wavelengths of 430 to 460 nm ４３０－４６０（ＡＶＥ） More than 95% (i-2) Average internal transmittance T in the spectral transmittance curve for wavelengths of 460 to 530 nm ４６０－５３０（ＡＶＥ） More than 97% (i-3) The absolute value of the difference between the shortest wavelength and the second shortest wavelength at which the internal transmittance is 50% at wavelengths of 600 nm or more is 125 nm or more. 【Chemistry 1】 Here, the symbols in formula (A) are as follows: R 1 to R 7 are each independently a hydrogen atom, a halogen atom, a sulfo group, a hydroxyl group, a cyano group, a nitro group, a carboxy group, a phosphate group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, or an acyloxy group having 1 to 10 carbon atoms which may have a substituent. Two adjacent groups of R 2 to R 5 and R 6 to R 7 may be linked to each other to form a ring having 5 to 8 members. Formula (A) optionally includes Z. Z is a 5- or 6-membered ring. X − represents PF 6 − , [Rf—SO 2 ] − , [N(Rf—SO 2 ) 2 ] − (Rf represents an alkyl group substituted with at least one fluorine atom), or BF 4 − . R 8 represents a hydrogen atom, a halogen atom, or -Y 5 -R 10 (Y 5 represents a single bond, an ether bond (-O-), a sulfonyl bond (-SO 2 -), an ester bond (-C(=O)-O- or -O-C(=O)-) or a ureido bond (-NH-C(=O)-NH-), and R 10 represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms which may have a substituent).

2. the resin film further contains a dye (B) having a maximum absorption wavelength in dichloromethane at 650 to 730 nm; 2. The optical filter according to claim 1, wherein the resin film satisfies all of the following spectral characteristics (ii-1) to (ii-4): (ii-1) When the content of the dye (A) in the resin film is [A] (mass%) and the content of the dye (B) in the resin film is [B] (mass%), [A] / [B]<0.85 (ii-2) Internal transmittance T at a wavelength of 700 nm ７００ Less than 5% (ii-3) Average internal transmittance T in the spectral transmittance curve for wavelengths of 730 to 800 nm ７３０－８００（ＡＶＥ） Less than 25% (ii-4) Average internal transmittance T in the spectral transmittance curve of 430 to 460 nm ４３０－４６０（ＡＶＥ） More than 92%

3. 3. The optical filter of claim 2, wherein the dye (B) is a squarylium dye.

4. 4. 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.

5. 5. The optical filter of claim 4, wherein the support is glass or an absorbing glass.

6. 6. The optical filter according to claim 1, wherein the resin includes a polyimide resin.

7. The optical filter according to any one of claims 1 to 6, which satisfies all of the following spectral characteristics (iii-1) to (iii-3): (iii-1) Maximum transmittance T in a spectral transmittance curve with a wavelength of 730 to 800 nm and an incident angle of 60 degrees ７３０－８００（６０°）（ＭＡＸ） is 1.5% or less (iii-2) Average transmittance T in a spectral transmittance curve with a wavelength of 435 to 480 nm and an incident angle of 0 degrees ４３５－４８０（０°）（ＡＶＥ） More than 85% (iii-3) Average transmittance T in a spectral transmittance curve with a wavelength of 435 to 480 nm and an incident angle of 30 degrees ４３５－４８０（３０°）（ＡＶＥ） More than 85%

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