Filter

Abstract

One embodiment of the filter of the present invention comprises a transparent substrate having a first main surface and a first light-absorbing layer disposed on the first main surface side of the transparent substrate. The first light-absorbing layer comprises a near-infrared absorbing pigment and an inorganic material. The near-infrared absorbing pigment has a maximum absorption wavelength at a wavelength of 650 nm to 760 nm and a molecular weight of 2000 or less.

Description

Technical Field

[0001] This invention relates to a filter. Prior Technology

[0002] Digital cameras and camcorders, among other imaging devices, incorporate solid-state imaging elements (CCD (Charge Coupled Device), CMOS (Complementary Metal Oxide Semiconductor), etc.) to sense people or scenery. Solid-state imaging elements exhibit a higher sensitivity to infrared light than human vision. Therefore, to make the images obtained using solid-state imaging elements closer to human vision, filters such as near-infrared cut-off filters are incorporated into the imaging device.

[0003] Generally, such filters are constructed by providing a light-absorbing layer that blocks near-infrared light on a transparent substrate. For example, Patent Document 1 discloses a near-infrared cutoff filter, which includes a laminated plate having a resin layer on at least one side of a glass substrate, and the resin layer contains a pigment as a near-infrared absorber. Previous technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2012-103340 Summary of the Invention

[0005] [The problem the invention aims to solve]

[0006] In recent years, especially with the increasing performance of camera devices in smartphones, there has been a demand for filters with excellent light resistance.

[0007] However, in the near-infrared cutoff filter of Patent Document 1, the pigment, which serves as the near-infrared absorber, is contained within the resin layer. Therefore, the pigment may react with the hydroxyl groups in the resin under sunlight or indoor light, undergoing photo-oxidation and deteriorating. Consequently, the lightfastness of the near-infrared cutoff filter of Patent Document 1 may not be sufficient.

[0008] One objective of this invention is to provide a filter with excellent lightfastness and near-infrared shielding properties. [Technical means to solve the problem]

[0009] One aspect of the filter of the present invention comprises a transparent substrate having a first main surface and a first light-absorbing layer disposed on the first main surface side of the transparent substrate. The first light-absorbing layer comprises a near-infrared absorbing pigment and an inorganic material. The near-infrared absorbing pigment has a maximum absorption wavelength at a wavelength of 650 nm to 760 nm and a molecular weight of 2000 or less. [Effects of the Invention]

[0010] One embodiment of the present invention can provide a filter with excellent light resistance and near-infrared shielding properties. Simple Explanation of the Diagram

[0011] Figure 1 is a schematic cross-sectional view of a filter according to one embodiment of the present invention. Figure 2 is a schematic cross-sectional view of a first variation of the filter according to one embodiment of the present invention. Figure 3 is a schematic cross-sectional view of a second variation of the filter according to one embodiment of the present invention. Figure 4 is a schematic cross-sectional view of a third variation of the filter according to one embodiment of the present invention. Figure 5 is a schematic cross-sectional view of the fourth variation of the filter according to one embodiment of the present invention. Figure 6 is a schematic cross-sectional view of the fifth variation of the filter according to one embodiment of the present invention. Figure 7 shows the spectral transmittance curves of the filter in Example 1 before and after the lightfastness test. Figure 8 shows the spectral transmittance curves of the filter in Example 2 before and after the lightfastness test. Figure 9 shows the spectral transmittance curves of the filter in Example 3 before and after the lightfastness test. Figure 10 shows the spectral transmittance curves of the filter in Example 4 before and after the lightfastness test. Figure 11 is a graph showing the spectral transmittance curve of the filter in Example 5. Figure 12 is a graph showing the spectral transmittance curve of the filter in Example 6. Figure 13 is a graph showing the spectral transmittance curve of the filter in Example 7. Figure 14 is a graph showing the spectral transmittance curve of the filter in Example 8. Figure 15 shows the spectral transmittance curves of the filter in Example 9 before and after the lightfastness test. Implementation

[0012] The embodiments of the present invention will be described in detail below.

[0013] A filter according to one embodiment will be described. FIG1 is a schematic cross-sectional view of a filter according to one embodiment of the present invention. As shown in FIG1, the filter 10 has a transparent substrate 1 and a first light-absorbing layer 2 disposed on a main surface (first main surface) of the transparent substrate 1.

[0014] [Transparent substrate] The transparent substrate 1 can contain any material as long as it is transparent to visible light (high transmittance). For example, the transparent substrate 1 can contain glass (white glass, near-infrared absorbing glass, etc.) or resin.

[0015] [First light absorption layer] The first light-absorbing layer 2 is a layer that absorbs near-infrared radiation. The first light-absorbing layer 2 is a layer containing a near-infrared absorbing pigment (A) and an inorganic material (B). Typically, it is a layer in which the near-infrared absorbing pigment (A) is dispersed within the inorganic material (B). In other words, it is a layer in which the inorganic material (B) and the near-infrared absorbing pigment (A) are mixed. The infrared absorbing pigment (A) can be uniformly dispersed in the inorganic material (B), or its concentration can vary along the orthogonal direction (thickness direction) of the first main surface of the transparent substrate 1.

[0016] (Near-infrared absorbing pigment) There are no particular restrictions on near-infrared absorbing pigments (A) as long as they have a maximum absorption wavelength (hereinafter referred to as "λmax") in the wavelength region of 650 nm to 760 nm and a molecular weight of less than 2000. Furthermore, λmax has an absorption peak with an absorption apex (hereinafter referred to as "the absorption peak of λmax"). Preferably, the absorption curve of the near-infrared absorbing pigment (A) not only has λmax in the wavelength region of 650 nm to 760 nm, but also exhibits less absorption in the visible light region, and the slope of the absorption peak of λmax on the visible light side is steep. Furthermore, the absorption peak of λmax preferably has a gentle slope on the longer wavelength side.

[0017] Regarding the λmax of the near-infrared absorbing pigment (A), an absorption curve in the wavelength region of 400 nm to 850 nm can be obtained by using a solution prepared by dissolving the near-infrared absorbing pigment (A) in dichloromethane, for example, using a UV-Vis-NIR spectrophotometer (manufactured by Nippon Spectrophotometer Co., Ltd., model: V770). The λmax of the aforementioned near-infrared absorbing pigment (A) can be detected from this absorption curve. In this specification, unless otherwise specified, the absorption curve is conveniently measured at an incident angle of 0°.

[0018] The near-infrared absorbing pigment (A) has a maximum absorption wavelength in the wavelength region of 650 nm to 760 nm, thereby endowing the filter 10 with excellent ability to absorb light in the near-infrared wavelength region (700 nm to 1100 nm). Furthermore, the near-infrared absorbing pigment (A) has a molecular weight of less than 2000, allowing it to be formed on a transparent substrate at low temperatures. Therefore, thermal degradation of the near-infrared absorbing pigment (A) can be suppressed, and the filter 10 can obtain the desired near-infrared absorption characteristics.

[0019] Examples of near-infrared absorbing pigments (A) include: anthocyanin compounds, phthalocyanine compounds, naphthyl phthalocyanine compounds, dithiol metal complexes, diamine compounds, polymethyl compounds, phthalolides, naphthoquinone compounds, anthraquinone compounds, indophenol compounds, and squaric acid ononium compounds.

[0020] Among these, squartzium compounds, anthocyanin compounds, and phthalocyanine compounds are preferred, with squartzium compounds being particularly preferred. Regarding the near-infrared absorbing pigment (A) containing squartzium compounds, its absorption curve shows less absorption in the visible light region, a steep slope of the absorption peak at λmax on the visible light side, and higher storage stability and light stability, thus it is preferred. Regarding the near-infrared absorbing pigment (A) containing anthocyanin compounds, its absorption curve shows less absorption in the visible light region, and higher absorption rate of long-wavelength light in the wavelength region near λmax, thus it is preferred. Furthermore, anthocyanin compounds are known to have been used as recording pigments for CD-Rs (Compact Disc-Recordable) and the like, due to their low cost and the ability to ensure long-term stability through salt formation. The near-infrared absorbing pigment (A) containing phthalocyanine compounds exhibits excellent heat resistance and weather resistance, thus it is preferred.

[0021] Regarding the near-infrared absorbing pigment (A) as a squaric acid ononium compound, specifically, at least one of the squaric acid ononium compounds represented by the following formula (F1) can be cited as examples. In this specification, the compound represented by formula (F1) is referred to as compound (F1). The same applies to other compounds.

[0022] Compound (F1) is a squaric acid-based compound having the following structure: a benzene ring is bonded to the left and right sides of the squaric acid skeleton, and a nitrogen atom is bonded to the 4-position of the benzene ring, forming a saturated heterocycle containing the nitrogen atom. Compound (F1) is a compound that has the light absorption properties of the aforementioned near-infrared absorbing pigment (A). Regarding compound (F1), the substituents of the benzene ring can be appropriately adjusted within the following range according to other required properties, such as improving the solubility in the solvent (hereinafter, sometimes referred to as the "main solvent") or inorganic material (B) used in forming the first light-absorbing layer.

[0023] [Chemistry 1]

[0024] The symbols in formula (F1) are as follows. R4 and R6 independently represent hydrogen atom, halogen atom, hydroxyl group, alkyl group with 1 to 20 carbon atoms, alkoxy group with 1 to 20 carbon atoms, aceoxy group with 1 to 10 carbon atoms, aryl group with 6 to 11 carbon atoms, alkylaryl group with 7 to 18 carbon atoms that may have substituents and may have oxygen atoms between carbon atoms, -NR7R8 (R7 and R8 independently represent hydrogen atom, alkyl group with 1 to 20 carbon atoms, -C(=O)-R9 (R9 is hydrogen atom, halogen atom, hydroxyl group, may have substituents and may contain unsaturated bonds between carbon atoms, oxygen atom, alkyl group with 1 to 25 carbon atoms with saturated or unsaturated ring structure), -NHR10, or -SO2-R10 (R 10 represents one or more hydrogen atoms that may be replaced by halogen atoms, hydroxyl groups, carboxyl groups, sulfonyl groups, or cyano groups and may contain unsaturated bonds, oxygen atoms, saturated or unsaturated ring structures of hydrocarbon groups with 1 to 25 carbon atoms), or groups represented by the following formula (S) (R 41, R 42 independently represent hydrogen atoms, halogen atoms, or alkyl groups with 1 to 10 carbon atoms or alkoxy groups with 1 to 10 carbon atoms, k is 2 or 3).

[0025] [Chemistry 2] R1 and R2, R2 and R5, and R1 and R3 can be linked together to form heterocycles A, B, and C with a number of 5 or 6, together with nitrogen atoms.

[0026] Regarding R1 and R2 in the formation of heterocyclic A, as divalent groups -Q- formed by their equal bonding, it indicates that the hydrogen atom can be substituted by an alkyl group with 1 to 6 carbons, an aryl group with 6 to 10 carbons, or an alkyl group or alkoxy group with 1 to 10 carbons that has a substituent.

[0027] Regarding R2 and R5 in the formation of heterocycle B, and R1 and R3 in the formation of heterocycle C, as the divalent groups -X1-Y1- and -X2-Y2- formed by their isotropic bonding (with X1 and X2 on the nitrogen-bonded side), X1 and X2 are respectively represented by the following formula (1x) or (2x), and Y1 and Y2 are respectively represented by any one of the following formulas (1y) to (5y). When X1 and X2 are respectively represented by the following formula (2x), Y1 and Y2 can each be a single bond.

[0028] [Chemistry 3]

[0029] In formula (1x), the four Zs independently represent a hydrogen atom, a hydroxyl group, an alkyl or alkoxy group having 1 to 6 carbon atoms, or -NR 28R 29 (R 28 and R 29 independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms). R 21 to R 26 independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and R 27 represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms.

[0030] R7, R8, R9, R4, R6, R21~R27, R1~R3 ​​(when no heterocyclic ring is formed), and R5 can bond with any of the others to form a 5-membered or 6-membered ring. R21 and R26, and R21 and R27 can be directly bonded.

[0031] When no heterocycle is formed, R1 and R2 independently represent a hydrogen atom, an alkyl or allyl group having 1 to 6 carbon atoms that may have substituents, or an aryl or alkylaryl group having 6 to 11 carbon atoms. When no heterocycle is formed, R3 and R5 independently represent a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 6 carbon atoms.

[0032] Hereinafter, heterocyclic A will sometimes be simply referred to as ring A. The same applies to heterocyclic B and heterocyclic C.

[0033] In compound (F1), R4 and R6 independently represent the aforementioned atoms or groups. Examples of halogen atoms include fluorine, chlorine, and bromine. The alkyl group can be straight-chain, branched, or cyclic. Preferably, either R4 or R6 is a hydrogen atom, and the other is a combination of -NR7R8.

[0034] When compound (F1) has only ring A, only ring B, and ring C, or rings A through C, -NR 7R 8 can be introduced into either R 4 or R 6. When compound (F1) has only ring B, only ring A, and ring B, -NR 7R 8 is preferably introduced into R 4. Similarly, when compound (F1) has only ring C, only ring A, and ring C, -NR 7R 8 is preferably introduced into R 6.

[0035] As for -NR 7R 8, -NHC(=O)-R 9 is preferred from the viewpoint of solubility in the main solvent or inorganic material (B). As for R 9, it is preferred to be an alkyl group with 1 to 20 carbon atoms that may have substituents, an aryl group with 6 to 10 carbon atoms that may have substituents, or an alkylaryl group with 7 to 18 carbon atoms that may have substituents and oxygen atoms between carbon atoms. Examples of substituents include: fluorine atoms, alkyl groups with 1 to 6 carbon atoms, fluoroalkyl groups with 1 to 6 carbon atoms, alkoxy groups with 1 to 6 carbon atoms, aceoxy groups with 1 to 6 carbon atoms, etc.

[0036] As R 9, among these, it is preferably selected from the following groups: linear, branched, or cyclic alkyl groups having 1 to 17 carbon atoms that can be substituted with fluorine atoms; phenyl groups having substituted with fluoroalkyl groups having 1 to 6 carbon atoms and / or alkoxy groups having substituted with phenyl groups having 1 to 6 carbon atoms and / or having substituted with alkyl groups having 1 to 6 carbon atoms and / or having substituted with alkoxy groups having 1 to 6 carbon atoms at the 7 to 18th carbon atom with oxygen atoms between carbon atoms.

[0037] In compound (F1), for rings A, B, and C with a number of 5 or 6 formed by R1 and R2, R2 and R5, and R1 and R3 respectively, it is sufficient to form at least one of them, or two or three.

[0038] When no ring is formed, R1 and R2 independently represent a hydrogen atom, an alkyl or allyl group having 1 to 6 carbon atoms that may have substituents, or an aryl or alkylaryl group having 6 to 11 carbon atoms. The alkyl group can be straight-chain, branched, or cyclic. Examples of substituents include hydroxyl, alkoxy, and acetoxy groups having 1 to 3 carbon atoms. When no ring is formed, R3 and R5 independently represent a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 6 carbon atoms. Among these, R1, R2, R3, and R5 are preferably alkyl groups having 1 to 3 carbon atoms, especially methyl or 2-propyl, from the viewpoint of solubility in the main solvent or inorganic material (B).

[0039] Furthermore, in compound (F1), the groups R1 to R6 of the benzene rings bonded to the left and right sides of the squaric acid skeleton can be different on the left and right sides, but it is preferable that they are the same on the left and right sides.

[0040] Furthermore, compound (F1) includes compound (F1-1) represented by formula (F1-1), which has a resonance structure of the structure represented by the general formula (F1) mentioned above.

[0041] [Chemistry 4]

[0042] The symbols in equation (F1-1) are the same as those in equation (F1) above.

[0043] As a compound (F1), more specifically, examples include: the compound represented by formula (F11) having only ring B as a ring structure; the compound represented by formula (F12) having only ring A as a ring structure; and the compound represented by formula (F13) having both ring B and ring C as ring structures. Furthermore, the compound represented by formula (F11) is the same compound as the compound (F1) having only ring C as a ring structure, and R6 being -NR7R8. Also, the compounds represented by formula (F11) and formula (F13) are compounds described in U.S. Patent No. 5,543,086.

[0044] [Chemistry 5]

[0045] [Chemistry 6]

[0046] [Chemistry 7]

[0047] The symbols in equations (F11) to (F13) are the same as those in equation (F1) above, and the preferred state is also the same.

[0048] In compound (F11), X1 is preferably an ethyl group in which the hydrogen atom represented by (2x) above may be substituted with an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms. In this case, the substituent is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. Specifically, examples of X1 include: -(CH2)2-, -CH2-C(CH3)2-, -CH(CH3)-C(CH3)2-, -C(CH3)2-C(CH3)2-, etc. As for -NR 7R 8 in compound (F11), the preferred alternatives are -NH-C(=O)-CH 3, -NH-C(=O)-C 6H 13, -NH-C(=O)-C 6H 5, -NH-C(=O)-CH(C 2H 5)-C 4H 9, -NH-C(=O)-C(CH 3) 2-C 2H 5, -NH-C(=O)-C(CH 3) 2-C 3H 7, -NH-C(=O)-C(CH 3) 2-(CH 2) 3-OC 6H 3(CH 3) 2, etc.

[0049] Examples of compounds (F11) include those represented by formulas (F11-1), (F11-2), (F11-3), (F11-4), (F11-5), (F11-6), (F11-7), and (F11-8). Among these, compounds (F11-2), (F11-3), (F11-4), (F11-5), (F11-6), (F11-7), and (F11-8) are preferred in terms of their higher solubility in the main solvent or inorganic material (B).

[0050] [Chemistry 8]

[0051] [Chemistry 9]

[0052] [Chemistry 10]

[0053] [Chemistry 11]

[0054] [Chemistry 12]

[0055] [Chemistry 13]

[0056] [Chemistry 14]

[0057] [Chemistry 15]

[0058] In compound (F12), Q is a hydrogen atom that can be substituted by an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an alkyl group having 1 to 10 carbon atoms that has a substituent, such as an alkyl group having 4 or 5 carbon atoms, or an alkoxy group having 3 or 4 carbon atoms. In the case of an alkoxy group, the oxygen atom is preferably not adjacent to N. Furthermore, Q is preferably an alkyl group having 1 to 3 carbon atoms, especially an alkyl group having 1 to 3 carbon atoms, such as an alkyl group having 1 to 3 carbon atoms, particularly an alkyl group having 1 to 3 carbon atoms, such as an alkyl group having 1 to 3 carbon atoms, such as an alkyl group having 1 to 3 carbon atoms, such as an alkyl group having 1 to 3 carbon atoms.

[0059] In compound (F12), -NR 7R 8 is preferably -NH-C(=O)-(CH 2) m-CH 3 (m is 0~19) or -NH-C(=O)-Ph-R 10 (-Ph- represents phenyl, R 10 represents hydrogen atom, hydrogen atom can be replaced by alkyl with 1~3 carbon atoms of fluorine atom or alkoxy with 1~3 carbon atoms), etc.

[0060] Here, the λmax of compound (F12) is on the relatively long wavelength side of the aforementioned wavelength region. Therefore, if compound (F12) is used, the transmission area of ​​the visible band can be extended. Examples of compounds (F12) include those represented by the following formulas (F12-1), (F12-2), and (F12-3).

[0061] [Chemistry 16]

[0062] [Chemistry 17]

[0063] [Chemistry 18]

[0064] In compound (F13), X1 and X2 are preferably, independently, ethyl groups in which the hydrogen atom represented by (2x) can be substituted with an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms. In this case, the substituent is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. Specifically, examples of X1 and X2 include: -(CH2)2-, -CH2-C(CH3)2-, -CH(CH3)-C(CH3)2-, -C(CH3)2-C(CH3)2-, etc. Examples of Y1 and Y2 are independently: -CH2-, -C(CH3)2-, -CH(C6H5)-, -CH((CH2)mCH3)- (m is 0 to 5), etc. In compound (F13), -NR 7R 8 is preferably -NH-C(=O)-C mH 2m + 1 (m is 1~20, C mH 2m + 1 can be any of straight chain, branched chain, or cyclic), -NH-C(=O)-Ph-R 10 (-Ph- represents phenyl, R 10 represents hydrogen atom, alkyl with 1~3 carbon atoms, alkoxy with 1~3 carbon atoms, or perfluoroalkyl with 1~3 carbon atoms), etc.

[0065] As a compound (F13), examples can be given of compounds represented by the following formulas (F13-1) and (F13-2).

[0066] [Chemistry 19]

[0067] [Chemistry 20]

[0068] Furthermore, as a near-infrared absorbing pigment (A), a squaric acid-based compound represented by the following formula (F2) may also be used. Formula (F2) represents a compound of formula (F1) that does not form any of rings A, B, or C (wherein R1 to R6 are described below).

[0069] [Chemistry 21]

[0070] The symbols in formula (F2) are as follows. R1 and R2 independently represent a hydrogen atom, an alkyl or allyl group with 1 to 12 carbon atoms that may have substituents, or an aryl or alkylaryl group with 6 to 11 carbon atoms. R3 and R5 independently represent a hydrogen atom, a halogen atom, or an alkyl or alkoxy group with 1 to 6 carbon atoms. R4 and R6 independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl or alkoxy group with 1 to 6 carbon atoms, an acetoxy group with 1 to 10 carbon atoms, or -NR7R8 (R7 and R8 are independently hydrogen atoms, an alkyl group with 1 to 20 carbon atoms, or -C(=O)-R9 (R9 is a hydrogen atom, an alkyl group with 1 to 20 carbon atoms that may have substituents, or an aryl group with 6 to 11 carbon atoms, or an alkylaryl group with 7 to 18 carbon atoms that may have substituents and may have oxygen atoms between carbon atoms)).

[0071] As a compound (F2), examples include compounds represented by formulas (F2-1) and (F2-2).

[0072] [Chemistry 22]

[0073] [Chemistry 23]

[0074] Furthermore, as a near-infrared absorbing pigment (A), a squaric acid-based compound represented by the following formula (F3) can also be used.

[0075] [Chemistry 24]

[0076] The aforementioned compounds (F11), (F12), (F13), etc., including compound (F11), or compounds (F2), (F3), can be manufactured by known methods. Compound (F11), such as compound (F11-1), can be manufactured, for example, by the method described in U.S. Patent No. 5,543,086. Furthermore, compound (F12) can be manufactured, for example, by the method described in J. Org. Chem. 2005, 70(13), 5164-5173.

[0077] When the near-infrared absorbing pigment (A) is a squaric acid onium compound, commercially available products can also be used. Examples of commercially available products include S2098 and S2084 (trade name, manufactured by FEW Chemicals).

[0078] Regarding near-infrared absorbing pigments (A) that are anthocyanin compounds, specifically, at least one of the anthocyanin compounds represented by the following formula (F4) can be cited as examples.

[0079] [Chemistry 25]

[0080] In formula (F4), the symbols are as follows. R 11 independently represent alkyl, alkoxy or alkylene groups having 1 to 20 carbon atoms, or their anionic species.

[0081] R12 and R13 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.

[0082] Z represents PF6, ClO4, Rf-SO2, (Rf-SO2)2-N (Rf represents an alkyl group with 1 to 8 carbon atoms in which at least one hydrogen atom is replaced by a fluorine atom), or BF4.

[0083] R 14, R 15, R 16 and R 17 each independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms. N represents an integer from 1 to 6.

[0084] Furthermore, in compound (F4), R11 is preferably an alkyl group with 1 to 20 carbon atoms, and R12 and R13 are each preferably hydrogen atoms or alkyl groups with 1 to 6 carbon atoms. R14, R15, R16 and R17 are each preferably hydrogen atoms, and the number of n is preferably 1 to 4. The left and right structures separated by n repeating units can be different, but are preferably the same.

[0085] As a compound (F4), more specifically, examples can be given by compounds represented by the following formula (F4-1), compounds represented by the following formula (F4-2), etc. The anion represented by Z- is the same as Z- in (F4) above.

[0086] [Chemistry 26]

[0087] [Chemistry 27]

[0088] Near-infrared absorbing pigments (A) that are anthocyanin compounds can also be used in commercially available products. Examples of commercially available products include: ADS680HO (trade name, manufactured by American Dye), S0830 (trade name, manufactured by FEW Chemicals), and S2137 (trade name, manufactured by FEW Chemicals).

[0089] Furthermore, examples of commercially available phthalocyanine compounds that can be used as near-infrared absorbing pigments (A) include FB22 (trade name, manufactured by Yamada Chemical Industry Co., Ltd.), TXEX720 (trade name, manufactured by Nippon Shokubai Co., Ltd.), and PC142c (trade name, manufactured by Yamada Chemical Industry Co., Ltd.).

[0090] In this embodiment, one of a plurality of compounds selected from those having the maximum absorption wavelength in the wavelength region of 650 nm to 760 nm can be used alone as the near-infrared absorbing pigment (A), or two or more can be used together. The near-infrared absorbing pigment (A) preferably contains one or more of the aforementioned near-infrared absorbing pigments (A). Furthermore, the near-infrared absorbing pigment (A) may also contain any near-infrared absorbing pigment as needed. When using a plurality of near-infrared absorbing pigments as the near-infrared absorbing pigment (A), it is preferable to combine these near-infrared absorbing pigments in a manner that exhibits the maximum absorption wavelength in the wavelength region of 650 nm to 760 nm. Furthermore, it is preferable to combine the near-infrared absorbing pigments in such a manner that, in the absorption curve, the absorption in the visible light region is less, the slope of the absorption peak at λmax on the visible light side is steep, and the slope on the longer wavelength side is gentle. Alternatively, near-infrared absorbing pigments selected from a plurality of compounds having a maximum absorption wavelength outside the wavelength region of 650 nm to 760 nm can be used in combination with near-infrared absorbing pigment (A).

[0091] (Inorganic materials) As an inorganic material (B), it is preferably an inorganic material with a refractive index of 1.38 to 2.20 at a wavelength of 500 nm.

[0092] Specifically, examples of inorganic materials (B) include: silicon dioxide, aluminum oxide, magnesium fluoride, sodium fluoride, lanthanum fluoride, lithium fluoride, calcium fluoride, barium fluoride, lanthanum oxide, cerium oxide, germanium oxide, indium oxide, magnesium oxide, zirconium oxide, tantalum oxide, yttrium oxide, tungsten oxide, zinc oxide, ITO, materials obtained by changing the valence of these compounds, and composite materials obtained by mixing any one of these as the main component and adjusting the refractive index. Among these, from the viewpoint that a smaller refractive index difference with the transparent substrate 1 makes it easier to deliberately adjust the spectroscopic characteristics and ensure practical reliability, the inorganic material is preferably selected from one or more of silicon dioxide, aluminum oxide, and magnesium fluoride. Furthermore, when using an inorganic material with a refractive index of 1.38 to 2.20 at a wavelength of 500 nm as inorganic material (B), as long as the overall refractive index is within this range, one of these inorganic materials can be used alone, or two or more can be mixed and used.

[0093] In filter 10, the matrix material used to disperse the near-infrared absorbing pigment (A) is an inorganic material. Therefore, it is believed that compared with the case where the matrix material is resin, it has fewer hydroxyl groups, which can inhibit the photo-oxidation of the near-infrared absorbing pigment (A) caused by sunlight or indoor light. Therefore, filter 10 can exhibit excellent lightfastness and near-infrared shielding properties.

[0094] The thickness of the first light-absorbing layer 2 is not particularly limited and can be appropriately determined according to the application, i.e., the placement space within the device in which it is used, or the required absorption characteristics. The thickness of the first light-absorbing layer 2 is preferably 0.1 μm to 100 μm. If the thickness is less than 0.1 μm, there is a risk that the near-infrared absorption capability may not be sufficiently exhibited. Furthermore, if the thickness exceeds 100 μm, the flatness of the film decreases, potentially resulting in uneven absorption. The thickness is more preferably 0.2 μm to 0.7 μm. Within this range, sufficient near-infrared absorption capability can be obtained. Moreover, in this specification, film thickness refers to physical film thickness.

[0095] The first light-absorbing layer 2 may also contain any other components as needed, in addition to the near-infrared absorbing pigment (A) and the inorganic material (B), without hindering the effects of the present invention. Specifically, examples of such components include: near-infrared or infrared absorbers, tone-correcting pigments, ultraviolet absorbers, leveling agents, antistatic agents, heat stabilizers, light stabilizers, antioxidants, etc. Preferably, the content of these components in the first light-absorbing layer 2 is 15 parts by mass or less relative to 100 parts by mass of the inorganic material (B).

[0096] As any component, it is preferably an ultraviolet absorber containing any of the above-mentioned components. The first light-absorbing layer 2, by containing an ultraviolet absorber, can perform both the function of absorbing near-infrared rays and the function of absorbing ultraviolet rays.

[0097] Examples of UV absorbers include triterpenoid compounds, indole compounds, methylimine compounds, benzotriazole compounds, anthocyanin compounds, benzoxazole compounds, and other UV-absorbing pigments (C), as well as inorganic UV absorbers. In terms of high absorbance, efficient absorption of the desired UV wavelength, and low transmittance in the visible wavelength range due to its high steepness, the aforementioned UV-absorbing pigments (C) are preferred UV absorbers.

[0098] As ultraviolet-absorbing pigments (C), the preferred ones are anthocyanin compounds and benzo[a]azole compounds.

[0099] Regarding the ultraviolet-absorbing pigment (C) as a part-cyanide compound, it is more preferably a part-cyanide compound represented by the following formula (U1).

[0100] [Chemistry 28]

[0101] The symbols in formula (U1) are as follows. Y represents a methylene or oxygen atom substituted with R6 and R7. R1 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms that may have substituents. R2 to R7 each independently represent a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 10 carbon atoms. X represents any of the divalent groups represented by formulas (X1) to (X5) below (wherein, R8 and R9 each independently represent a monovalent hydrocarbon group having 1 to 12 carbon atoms that may have substituents, and R10 to R19 each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms that may have substituents).

[0102] [Chemistry 29]

[0103] In formula (U1), preferably R1, R8 and R9 are each a hydrogen atom, and the portion can be replaced by a cycloalkyl or phenyl alkyl group having 1 to 6 carbon atoms, and R2 to R7 and R10 to R19 are each a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0104] In formula (U1), preferably R1, R8 and R9 are each independently an alkyl group having 1 to 6 carbon atoms, and R2 to R7 and R10 to R19 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0105] As a compound (U1), examples can be given of compounds represented by the following formulas (U1-1), (U1-2), (U1-3), (U1-4), (U1-5), and (U1-6).

[0106] [Chemistry 30]

[0107] [Chemistry 31]

[0108] [Chemistry 32]

[0109] [Chemistry 33]

[0110] [Chemistry 34]

[0111] [Chemistry 35]

[0112] Regarding ultraviolet-absorbing pigments (C) that are benzoxazole compounds, examples include compounds represented by the following formula (U2-1).

[0113] [Chemistry 36]

[0114] Examples of inorganic ultraviolet absorbers include: zinc oxide, titanium oxide, cerium oxide, zirconium oxide, mica, kaolin, sericite, etc.

[0115] [Optical Properties] The filter 10 preferably has the characteristics described in (a-1) to (a-4) below. (a-1) The average transmittance of light with a wavelength of 440 nm to 500 nm at an incident angle of 0° is over 75%. (a-2) The average transmittance of light with a wavelength of 500 nm to 600 nm at an incident angle of 0° is over 75%. (a-3) When the transmittance of the infrared wavelength region at an incident angle of 0° is 50%, the difference between the wavelength on the short wavelength side and the wavelength on the long wavelength side is more than 35 nm. (a-4) The transmittance of light with a wavelength of 700 nm at an incident angle of 0° is less than 65%.

[0116] Transmittance is a value measured using a UV-Vis-NIR spectrophotometer. In this specification, average transmittance within a specific wavelength range refers to the average transmittance across all wavelengths within that range. Furthermore, when measuring light transmittance by incident light from a direction other than that orthogonal to the principal surface of the sample, the angle between the line representing the direction of light incidence and the line orthogonal to the principal surface is called the angle of incidence. Moreover, unless otherwise specified, light transmittance refers to the percentage of light incident from a direction orthogonal to the principal surface of the sample that travels directly through the sample to the opposite side.

[0117] By possessing the characteristics described in (a-1) to (a-4) above, the filter 10 exhibits excellent near-infrared shielding properties. Therefore, it enables high sensitivity in solid-state imaging devices.

[0118] The filters 40, 50, and 60 shown in Figures 4 to 6, which have a second light absorption layer 3, preferably have the characteristics described below (b-1) to (b-7). (b-1) In the ultraviolet wavelength region with an incident angle of light of 0° to 50°, there is a wavelength λUV50% with a light transmittance of 50%, and the wavelength λUV50% is within the range of 350 nm to 420 nm. (b-2) The difference between the above wavelength λUV50% at an incident angle of 0° and the above wavelength λUV50% at an incident angle of 30° is less than 10 nm. (b-3) The average transmittance of light with wavelengths of 440 nm to 500 nm at an incident angle of 0° is over 75%. (b-4) The average transmittance of light with a wavelength of 500 nm to 600 nm at an incident angle of 0° is over 75%. (b-5) Having a wavelength λIR50% with a light transmittance of 50% in the infrared wavelength region, and the difference between the above wavelength λIR50% at an incident angle of 0° and the above wavelength λIR50% at an incident angle of 30° is less than 10 nm. (b-6) The average transmittance of light with wavelengths of 750 nm to 1000 nm at an incident angle of 0° is less than 90%. (b-7) Having a wavelength λIR20% with a light transmittance of 20% in the infrared wavelength region, and the difference between the above wavelength λIR20% at an incident angle of 0° and the above wavelength λIR20% at an incident angle of 30° is less than 5 nm.

[0119] Filters 40, 50, and 60, which have a second light-absorbing layer 3, possess the characteristics described in (b-1) to (b-7) above, and thus exhibit excellent near-infrared and ultraviolet shielding properties. Therefore, they can improve the color reproduction of solid-state imaging devices and suppress noise such as flash or ghosting during shooting.

[0120] (Example of variation) Regarding variations of filter 10, references to Figures 2 through 6 will be used for explanation. Figure 2 is a schematic cross-sectional view of a first variation of the filter according to one embodiment of the present invention. Figure 3 is a schematic cross-sectional view of a second variation of the filter according to one embodiment of the present invention. Figure 4 is a schematic cross-sectional view of a third variation of the filter according to one embodiment of the present invention. Figure 5 is a schematic cross-sectional view of a fourth variation of the filter according to one embodiment of the present invention. Figure 6 is a schematic cross-sectional view of a fifth variation of the filter according to one embodiment of the present invention.

[0121] As shown in Figure 2, the first light-absorbing layer 2 may have an inorganic layer 21 containing inorganic material (B) and a pigment layer 22 containing near-infrared absorbing pigment (A). Furthermore, the interface between the inorganic layer 21 and the pigment layer 22 may be one that explicitly does not contain either the inorganic material (B) or the near-infrared absorbing pigment (A), or it may be a mixture of the inorganic material (B) and the near-infrared absorbing pigment (A). Figure 2 shows an example of lamination in the order of transparent substrate 1, inorganic layer 21, and pigment layer 22, but lamination may also be performed in the order of transparent substrate 1, pigment layer 22, and inorganic layer 21. Also, as shown in Figure 3, multiple alternating layers of inorganic layer 21 and pigment layer 22 may be laminated. In the example shown in Figure 3, the inorganic layer 21 and pigment layer 22 may also be laminated alternately in the reverse order.

[0122] As shown in Figure 4, the filter 40 may also have a second light-absorbing layer 3 on one of the main surfaces (first main surfaces) of the transparent substrate 1. In the example shown in Figure 4, the transparent substrate 1, the first light-absorbing layer 2, and the second light-absorbing layer 3 are laminated in that order. However, as shown in Figure 5, the filter 50 may also be laminated in the order of the transparent substrate 1, the second light-absorbing layer 3, and the first light-absorbing layer 2. Furthermore, as shown in Figure 6, the filter 60 may also have a first light-absorbing layer on the first main surface of the transparent substrate 1 and a second light-absorbing layer 3 on the second main surface of the transparent substrate 1.

[0123] The second light-absorbing layer 3 has an ultraviolet-absorbing pigment (C) with a maximum absorption wavelength of 300 nm to 430 nm and a matrix material. Specifically, the ultraviolet-absorbing pigment (C) can be the same as that used in the filter 10 shown in FIG1 above.

[0124] Regarding the λmax of the ultraviolet-absorbing pigment (C), an absorption curve can be obtained by using a solution prepared by dissolving the ultraviolet-absorbing pigment (C) in dichloromethane, for example, by measuring it with an ultraviolet-visible-near-infrared spectrophotometer (manufactured by Japan Spectrophotometer Co., Ltd., model: V770), and the λmax of the ultraviolet-absorbing pigment (C) can be detected from the absorption curve.

[0125] The ultraviolet-absorbing pigment (C) endows the filter 10 with excellent ability to absorb ultraviolet light in the ultraviolet wavelength region (300 nm to 430 nm) by having the maximum absorption wavelength in the wavelength region of 300 nm to 430 nm.

[0126] The matrix material can be an inorganic material or a resin. Specifically, as an inorganic material, the same inorganic material (B) as that used in the filter 10 shown in Figure 1 above can be used.

[0127] The resin is preferably a resin with a refractive index of 1.45 or higher. A refractive index of 1.5 or higher is more preferred, and 1.6 or higher is especially desirable. There is no upper limit to the refractive index of the resin, but in terms of ease of acquisition, around 1.72 is preferable.

[0128] Specifically, examples of resins include: acrylic resins, epoxy resins, olefin-thiol resins, polycarbonate resins, polyether resins, polyaryl ester resins, polyurethane resins, polyetherurethane resins, poly(p-phenylene oxide) resins, poly(aryl ether)phosphine oxide resins, polyimide resins, polyamide-imide resins, polyolefin resins, cyclic olefin resins, and polyester resins. One of these resins may be used alone, or two or more may be mixed. Furthermore, when using resins with a refractive index of 1.45 or higher, as long as the overall refractive index is 1.45 or higher, one of these resins may be used alone, or two or more may be mixed.

[0129] Of the above, considering the high solubility and high glass transition temperature of the ultraviolet-absorbing pigment (C), and the viewpoint of suppressing the thermal motion of the ultraviolet-absorbing pigment (C) to improve heat resistance, polyimide resin, polyester resin, and polycarbonate resin are preferred.

[0130] Furthermore, in this embodiment, filters 10, 20, 30, 40, 50, and 60 may have a protective layer provided on the surface (the surface in contact with the atmosphere) of the first light-absorbing layer 2 or the second light-absorbing layer 3. In the example shown in FIG6, protective layers may also be provided on both the surface of the first light-absorbing layer 2 and the surface of the second light-absorbing layer 3. Regarding the protective layer, by providing it on the surface of the first light-absorbing layer 2 or the second light-absorbing layer 3, the lightfastness of the filter can be improved by blocking light or moisture of a specific wavelength that reaches these light-absorbing layers.

[0131] The protective layer is not particularly limited and can be configured as an anti-reflective film, a reflective film that reflects light in a specific wavelength range, a selective wavelength shielding film that controls the transmission and shielding of light in a specific wavelength range, or a radiation shielding film that shields radiation such as alpha rays. Preferably, the protective layer possesses at least one of the following optical properties: optical properties that suppress visible light reflection, optical properties that reflect ultraviolet light, and optical properties that reflect infrared light. Specifically, for example, it can have at least one of the following: a visible light anti-reflective film that suppresses visible light reflection, an ultraviolet reflective film that reflects ultraviolet light, and an infrared reflective film that reflects infrared light. As a protective layer possessing such optical properties, an example is a dielectric multilayer film formed by stacking multiple layers of two or more dielectric films with different refractive indices.

[0132] Examples of materials constituting the protective layer include silicon dioxide, alumina, and composite materials with these as main components. The protective layer disposed on the surface of the first light-absorbing layer preferably contains the same material as the inorganic material (B). Furthermore, the protective layer disposed on the surface of the second light-absorbing layer preferably contains the same material as the matrix material. This results in a stronger adhesion between each light-absorbing layer and the protective layer, making them less prone to peeling. The protective layer can be a single layer or multiple layers containing different materials.

[0133] The thickness of the protective layer is preferably 0.01 μm to 10 μm, more preferably 0.1 μm to 5 μm, and from the viewpoint of thinning the filter, it is preferably thinner. Furthermore, when the protective layer comprises multiple layers, the total physical film thickness of the multiple layers is regarded as the film thickness of the protective layer.

[0134] (Manufacturing method) Regarding the manufacturing method of the filter 10, for example, a vacuum evaporation method is used, in which a near-infrared absorbing pigment (A) is heated by resistance heating and an inorganic material (B) is heated by an electron beam (EB) to form a first light-absorbing layer 2 on a transparent substrate 1. In the case of a filter 10 having a first light-absorbing layer 2 containing both near-infrared absorbing pigment (A) and ultraviolet absorbing pigment (C), for example, the near-infrared absorbing pigment (A) and ultraviolet absorbing pigment (C) are mixed and then heated by resistance heating. By using a vacuum evaporation method, compared to a wet film deposition process, the concentration of near-infrared absorbing pigment (A) contained in the first light-absorbing layer 2 can be higher, thus obtaining a filter with superior near-infrared shielding characteristics.

[0135] In the case of filter 20 shown in Figure 2, for example, an inorganic layer 21 is formed on a transparent substrate 1 by heating an inorganic material (B) with an electron beam (EB), and then a near-infrared absorbing pigment (A) is formed on the inorganic layer 21 by resistance heating. In the case of filter 30 shown in Figure 3, the above operations are repeated to form a plurality of stacked structures.

[0136] Regarding the filters 40, 50, and 60 shown in Figures 4-6, the vacuum evaporation method described above can also be applied, for example. As a method for fabricating the second light-absorbing layer 3, when an inorganic material is used as the matrix material, a vacuum evaporation method can be used, for example, to form it. When a resin is used, the following method can be used, for example, to form it. It can be manufactured by dispersing and dissolving ultraviolet-absorbing pigment (C) and resin (B) in a solvent to prepare a coating liquid, coating the coating liquid onto a transparent substrate 1 or the first light-absorbing layer 2, drying it, and then hardening it as needed.

[0137] When a protective layer is to be set, its formation can be achieved through vacuum film formation processes such as CVD (chemical vapor deposition), sputtering, and vacuum evaporation, or wet film formation processes such as spraying and immersion.

[0138] The embodiments of the present invention have been described above using filters 10, 20, 30, 40, 50, and 60 shown in Figures 1 to 6 as examples, but the filters are not limited to these. Their configuration can be appropriately modified as needed without departing from the spirit of the present invention. For example, any of the filters may include a reflective film that reflects light in a specific wavelength region, and a selective wavelength blocking film that controls the transmission and blocking of light in a specific wavelength region.

[0139] Filters 10, 20, 30, 40, 50, and 60 can be used as near-infrared filters for imaging devices such as smartphone cameras, digital still cameras or digital camcorders, surveillance cameras, vehicle cameras, and webcams, or for automatic exposure meters, as well as near-infrared filters for PDPs (Plasma Display Panels). Furthermore, the filters can be applied in the form of filters having two transmission bands: one for visible light and one for near-infrared light (e.g., only light with wavelengths of 850 nm or 940 nm), and blocking light of wavelengths outside these transmission bands. The filters of this invention are suitable for use in solid-state imaging devices such as smartphone cameras, digital still cameras or digital camcorders, surveillance cameras, vehicle cameras, and webcams. For example, the filters can be disposed between a camera lens and a solid-state imaging element. [Example]

[0140] Next, embodiments of the present invention will be described. The present invention is not limited to the embodiments and examples described below. In the following description, Examples 1 to 3 and Example 9 are embodiments, and Example 4 is a comparative example. Furthermore, Examples 5 to 8 are reference examples.

[0141] Fabricate filters according to Examples 1 to 9, as shown in Tables 1 and 2. Examples 1 to 9 will be described in detail below.

[0142] (Example 1) A flat glass plate (D263, manufactured by Schott Corporation) with dimensions of 50 mm in length, 50 mm in width, and 0.3 mm in thickness was used as the transparent substrate. Magnesium fluoride (MgF₂) was used as the matrix material, and compound (F11-7) (molecular weight 766.54, maximum absorption wavelength of 706 nm in dichloromethane solution, manufactured by Tokyo Chemical Industry Co., Ltd., product name: UVITEX OB) was used as the near-infrared absorbing pigment. The two were mixed and deposited on the glass plate using a vacuum evaporation apparatus to form a light-absorbing layer. Compound (F11-7) was synthesized based on an international publication (WO2014 / 088063). The light-absorbing layer thickness was appropriately adjusted to be between 200 nm and 700 nm. Silicon oxide (SiO₂) was deposited on the surface of the obtained light-absorbing layer using a vacuum evaporation apparatus to form a protective layer with a thickness of 100 nm or more, thereby obtaining the filter of Example 1.

[0143] (Example 2) Except that SiO2 was used as the matrix material in Example 1, the filter of Example 2 was obtained in the same manner as in Example 1.

[0144] (Example 3) Except for using compound (F11-8) (molecular weight 850.63, maximum absorption wavelength of 714 nm in dichloromethane solution) as the near-infrared absorbing pigment in Example 1, the filter of Example 3 was obtained in the same manner as in Example 1.

[0145] (Example 4) A solution was prepared by dissolving polyimide (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name: C-3G30G) in an organic solvent. A compound (F11-7) was mixed with the polyimide at a ratio of 4.5 parts by mass to 100 parts by mass as a near-infrared absorbing pigment. The solution was stirred and dissolved at room temperature to obtain a coating liquid. The obtained coating liquid was then spin-coated onto a flat glass plate (D263; manufactured by Schott Co., Ltd.) with dimensions of 50 mm in length, 50 mm in width, and 0.21 mm in thickness, serving as a transparent substrate. The organic solvent was removed by heating and drying to form a light-absorbing layer with a thickness of 1.11 μm, thereby obtaining the filter of Example 4.

[0146] (Example 5) Using SiO2 as the matrix material in Example 1, and compound (F11-8) (molecular weight 850.63, maximum absorption wavelength of 714 nm in dichloromethane solution) as the near-infrared absorbing pigment in Example 1, the filter of Example 5 was obtained in the same manner as in Example 1.

[0147] (Example 6) A flat glass plate (D263, manufactured by Schott) with dimensions of 50 mm in length, 50 mm in width, and 0.3 mm in thickness was used as a transparent substrate. Alumina (Al₂O₃) was used as the matrix material, and an inorganic layer with a thickness of 10 nm was formed on the glass plate by vacuum evaporation. Subsequently, on the surface of the obtained inorganic layer, a near-infrared absorbing pigment (F11-7) (molecular weight 766.54, maximum absorption wavelength of 706 nm in dichloromethane solution) was used as a pigment, and a pigment layer with a thickness of 13 nm to 20 nm was formed by vacuum evaporation. The formation of the inorganic layer was repeated 6 times, and the formation of the pigment layer was repeated 5 times. The inorganic layer and pigment layer were alternately deposited in units of 1 layer to form a light-absorbing layer containing a total of 11 layers. The outermost surface of the light-absorbing layer is an inorganic layer with a thickness of 10 nm, formed by vacuum evaporation of aluminum oxide (Al₂O₃). This inorganic layer serves as a protective layer. This is how the filter of Example 6 is obtained.

[0148] (Example 7) SiO2 was used as the matrix material in Example 6, and the SiO2 film thickness was 46 nm to 53 nm. Otherwise, the filter of Example 7 was obtained in the same manner as in Example 6. In Example 7, the outermost surface of the light absorption layer was an inorganic layer with a film thickness of 53 nm formed by vacuum evaporation using SiO2, which served as a protective layer.

[0149] (Example 8) Using SiO2 as the matrix material in Example 1, and without setting a protective layer, the filter of Example 8 was obtained in the same manner as in Example 1.

[0150] (Example 9) Magnesium fluoride (MgF2, 100 nm) was used instead of silicon oxide as a protective layer on the surface of the light-absorbing layer in Example 1. Otherwise, the filter of Example 9 was obtained in the same manner as in Example 1.

[0151] [Measurement of Spectral Transmittance] For the filters obtained in Examples 1 to 9, the transmittance at an incident angle of 0° was measured using a UV-Vis-NIR spectrophotometer (manufactured by Nippon Spectrophotometer Co., Ltd., model: V770) to obtain spectral transmittance curves. Figure 7 shows the spectral transmittance curve of the filter in Example 1, Figure 8 shows the spectral transmittance curve of the filter in Example 2, Figure 9 shows the spectral transmittance curve of the filter in Example 3, Figure 10 shows the spectral transmittance curve of the filter in Example 4, Figure 11 shows the spectral transmittance curve of the filter in Example 5, Figure 12 shows the spectral transmittance curve of the filter in Example 6, Figure 13 shows the spectral transmittance curve of the filter in Example 7, Figure 14 shows the spectral transmittance curve of the filter in Example 8, and Figure 15 shows the spectral transmittance curve of the filter in Example 9. As shown in Figures 7 to 15, it can be seen that the filters in Examples 1 to 9 have low transmittance of light near 700 nm and have near-infrared shielding characteristics.

[0152] [Evaluation of lightfastness] The filters obtained in Examples 1-4 and 9 were subjected to lightfastness tests to evaluate their lightfastness. In the lightfastness tests, a Super Xenon Weather Meter SX75 (manufactured by Suga Test Instruments) was used, and the filters were irradiated with light under the following conditions. (Irradiation conditions) Wavelength: 300~2450 nm Temperature: 40℃ Humidity: 50%RT Cumulative light intensity: 87.2 kW·h / m² After light irradiation, the transmittance at an incident angle of 0° was measured to obtain the spectral transmittance curve. Figure 7 shows the spectral transmittance curves of the filter in Example 1 before and after the lightfastness test; Figure 8 shows the spectral transmittance curves of the filter in Example 2 before and after the lightfastness test; Figure 9 shows the spectral transmittance curves of the filter in Example 3 before and after the lightfastness test; Figure 10 shows the spectral transmittance curves of the filter in Example 4 before and after the lightfastness test; and Figure 15 shows the spectral transmittance curves of the filter in Example 9 before and after the lightfastness test.

[0153] By analyzing the spectral transmittance curves before and after light irradiation, the minimum transmittance under light with wavelengths of 500 nm to 800 nm before and after irradiation is determined, and the change is calculated using the following formula. Minimum transmittance variation [%] = (Minimum transmittance of light with wavelengths of 500 nm to 800 nm before irradiation) - (Minimum transmittance of light with wavelengths of 500 nm to 800 nm after irradiation) The evaluation of lightfastness is set as follows: A is defined as the minimum transmittance variation [%] of less than 10%, and B is defined as the minimum transmittance variation [%] of more than 10%. Table 1 shows that A is considered to be qualified.

[0154] [Table 1] Example 1 Example 2 Example 3 Example 4 Example 9 Transparent substrate Glass (D263) Glass (D263) Glass (D263) Glass (D263) Glass (D263) Light absorption layer matrix materials MgF2 SiO 2 MgF2 Polyimide MgF2 Near-infrared absorbing pigments compound (F11-7) compound (F11-7) compound (F11-8) compound (F11-7) compound (F11-7) Maximum absorption wavelength of near-infrared absorbing pigments [nm] 706 706 714 706 706 Near-infrared absorbing pigment molecular weight 766.54 766.54 850.63 766.54 766.54 protective layer SiO 2 SiO 2 SiO 2 SiO 2 MgF2 Lightfastness A A A B A

[0155] [Table 2] Example 5 Example 6 Example 7 Example 8 Transparent substrate Glass (D263) Glass (D263) Glass (D263) Glass (D263) Light absorption layer matrix materials SiO 2 Al₂O₃ SiO 2 SiO 2 Near-infrared absorbing pigments compound (F11-8) compound (F11-7) compound (F11-7) compound (F11-7) Maximum absorption wavelength of near-infrared absorbing pigments [nm] 714 706 706 706 Near-infrared absorbing pigment molecular weight 850.63 766.54 766.54 766.54

[0156] As shown in Table 1, the filters in Examples 1-3 and 9, which use inorganic materials as the matrix material, are filters with good lightfastness. Since the matrix material is inorganic, it is believed that compared with the case where the matrix material is resin, there are fewer hydroxyl groups, and the photo-oxidation of near-infrared absorbing pigments (A) caused by light is suppressed.

[0157] (State of the invention) The present invention includes the following states. <State 1> A filter comprising a transparent substrate having a first main surface, and The first light-absorbing layer disposed on the first main surface side of the above-mentioned transparent substrate, and The aforementioned first light-absorbing layer includes near-infrared absorbing pigments and inorganic materials. The aforementioned near-infrared absorbing pigments have a maximum absorption wavelength of 650 nm to 760 nm and a molecular weight of less than 2000. <State 2> As described in Sample 1, the first light-absorbing layer is formed by a mixture of the near-infrared absorbing pigment and the inorganic material. <State 3> As described in Sample 2, the concentration of the near-infrared absorbing pigment is different in the orthogonal direction of the first principal surface. <State 4> As described in Sample 1, the first light-absorbing layer has a pigment layer containing the near-infrared absorbing pigment and an inorganic layer containing the inorganic material. <State 5> The filter described in any of the examples 1 to 4 has the following characteristics. (a-1) The average transmittance of light with a wavelength of 440 nm to 500 nm at an incident angle of 0° is over 75%. (a-2) The average transmittance of light with a wavelength of 500 nm to 600 nm at an incident angle of 0° is over 75%. (a-3) When the transmittance of the infrared wavelength region at an incident angle of 0° is 50%, the difference between the wavelength on the short wavelength side and the wavelength on the long wavelength side is more than 35 nm. (a-4) The transmittance of light with a wavelength of 700 nm at an incident angle of 0° is less than 65%. <State 6> The filter described in any one of samples 1 to 5, wherein the near-infrared absorbing pigment is selected from at least one of the group consisting of succinate compounds, phthalocyanine compounds, and anthocyanin compounds. <State 7> The filter described in sample 6 has the structure represented by the following formula (F1) of the above-mentioned squaric acid onium compound.

[0158] [Chemistry 1] The symbols in formula (F1) are as follows: R4 and R6 independently represent hydrogen atom, halogen atom, hydroxyl group, alkyl group with 1-20 carbon atoms, alkoxy group with 1-20 carbon atoms, aceoxy group with 1-10 carbon atoms, aryl group with 6-11 carbon atoms, alkylaryl group with 7-18 carbon atoms that may have substituents and may have oxygen atoms between carbon atoms, -NR7R8 (R7 and R8 independently represent hydrogen atom, alkyl group with 1-20 carbon atoms, -C(=O)-R9 (R9 is hydrogen atom, halogen atom, hydroxyl group, may have substituents and may contain unsaturated bonds between carbon atoms, oxygen atom, saturated or unsaturated ring structure of hydrocarbon group with 1-25 carbon atoms), -NHR10, or -SO2-R10 (R 10 represents one or more hydrogen atoms that may be replaced by halogen atoms, hydroxyl groups, carboxyl groups, sulfonyl groups, or cyano groups and may contain unsaturated bonds, oxygen atoms, saturated or unsaturated ring structures of hydrocarbon groups with 1 to 25 carbon atoms), or groups represented by the following formula (S) (R 41, R 42 independently represent hydrogen atoms, halogen atoms, or alkyl groups with 1 to 10 carbon atoms or alkoxy groups with 1 to 10 carbon atoms, k is 2 or 3).

[0159] [Chemistry 2] R1 and R2, R2 and R5, and R1 and R3 can be linked together to form heterocycles A, B, and C with a number of 5 or 6, together with nitrogen atoms. <State 8> The filter described in any of the examples 1 to 7 has a refractive index of 1.38 to 2.20 at a wavelength of 500 nm, as described above for the inorganic material. <State 9> As described in Sample 8, the inorganic material is selected from at least one of the group consisting of silicon dioxide, aluminum oxide, and magnesium fluoride. <Style 10> The filter described in any of the examples 1 to 9 has a protective layer on the surface of the first light-absorbing layer. <State 11> As described in Sample 10, the protective layer disposed on the surface of the first light-absorbing layer comprises the same material as the inorganic material. <Style 12> The filter described in sample 10 or 11 has a protective layer disposed on the surface of the first light-absorbing layer having at least one of the optical properties of suppressing visible light reflection, reflecting ultraviolet light, and reflecting infrared light. <State 13> The filter described in any one of 1 to 12 has a second light-absorbing layer on the first main surface side of the transparent substrate, and The second light-absorbing layer contains ultraviolet-absorbing pigments and matrix materials. The aforementioned ultraviolet-absorbing pigments have the maximum absorption wavelength in the range of 300 nm to 430 nm. <Style 14> As described in Sample 13, the matrix material is selected from any one of the group consisting of silicon dioxide, aluminum oxide, magnesium fluoride, polyimide resin, polyester resin, and polycarbonate resin. <Style 15> As described in sample 13 or 14, the ultraviolet-absorbing pigment is selected from at least one of the group consisting of triazine compounds, indole compounds, methylimine compounds, benzotriazole compounds, anthocyanin compounds, and benzotriazole compounds. <Style 16> The filter described in Sample 15 contains anthocyanin compounds represented by the formula (U1).

[0160] [Chemistry 3] The symbols in equation (U1) are as follows.

[0161] Y represents a methylene or oxygen atom substituted with R6 and R7.

[0162] R1 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms that may have substituents. R2 to R7 each independently represent a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 10 carbon atoms.

[0163] X represents any one of the divalent groups represented by the following formulas (X1) to (X5) (where R8 and R9 independently represent monovalent hydrocarbon groups with 1 to 12 carbon atoms that may have substituents, and R10 to R19 independently represent hydrogen atoms or monovalent hydrocarbon groups with 1 to 12 carbon atoms that may have substituents).

[0164] [Chemistry 4] <State 17> As described in sample 16, in formula (U1), R1, R8 and R9 are each independently a hydrogen atom and can be replaced by a cycloalkyl or phenyl alkyl group having 1 to 6 carbon atoms, and R2 to R7 and R10 to R19 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. <State 18> The filter described in sample 16, wherein in formula (U1), R1, R8 and R9 are each independently an alkyl group having 1 to 6 carbon atoms, and R2 to R7 and R10 to R19 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. <Style 19> As described in Sample 15, the ultraviolet-absorbing pigment is a benzoxazole compound. <Style 20> The filter described in any of 13 to 19 has a protective layer on the surface of the second light-absorbing layer. <State 21> As described in Sample 20, the protective layer on the surface of the second light-absorbing layer comprises the same material as the matrix material. <State 22> The filter described in sample 20 or 21 has a protective layer on the surface of the second light-absorbing layer having at least one of the optical properties of suppressing visible light reflection, reflecting ultraviolet light, and reflecting infrared light. <State 23> The filter described in any of 13 to 22 has the following characteristics. (b-1) In the ultraviolet wavelength region with an incident angle of light of 0° to 50°, there is a wavelength λUV50% that allows light transmittance of 50%, wherein the wavelength λUV50% is in the range of 350 nm to 420 nm. (b-2) The difference between the above wavelength λUV50% at an incident angle of 0° and the above wavelength λUV50% at an incident angle of 30° is less than 10 nm. (b-3) The average transmittance of light with wavelengths of 440 nm to 500 nm at an incident angle of 0° is over 75%. (b-4) The average transmittance of light with a wavelength of 500 nm to 600 nm at an incident angle of 0° is over 75%. (b-5) Having a wavelength λIR50% in the infrared wavelength region that allows light transmittance of 50%, wherein the difference between the aforementioned wavelength λIR50% at an incident angle of 0° and the aforementioned wavelength λIR50% at an incident angle of 30° is less than 10 nm. (b-6) The average transmittance of light with wavelengths of 750 nm to 1000 nm at an incident angle of 0° is less than 90%. (b-7) The wavelength λIR20% with a light transmittance of 20% in the infrared wavelength region, and the difference between the above wavelength λIR20% at an incident angle of 0° and the above wavelength λIR20% at an incident angle of 30° is less than 5 nm.

[0165] This international application claims priority based on Japanese Patent Application No. 2021-121013, filed on July 21, 2021, the entire contents of which are incorporated herein by reference.

[0166] 1: Transparent substrate 2: First light absorption layer 3: Second light absorption layer 10: Filters 20: Filter 21: Inorganic layer 22: Pigment layer 30: Filter 40: Filter 50: Filter 60: Filter

Claims

1. A filter comprising a transparent substrate having a first main surface and a first light-absorbing layer disposed on the first main surface side of the transparent substrate, wherein the first light-absorbing layer is a vapor-deposited film comprising a near-infrared absorbing pigment and an inorganic material, wherein the near-infrared absorbing pigment has a maximum absorption wavelength at a wavelength of 650 nm to 760 nm and a molecular weight of 2000 or less.

2. The filter of claim 1, wherein the first light-absorbing layer is formed by a mixture of the near-infrared absorbing pigment and the inorganic material.

3. The filter of claim 2, wherein the concentration of the near-infrared absorbing pigment is different in the orthogonal direction of the first principal surface.

4. The filter of claim 1, wherein the first light-absorbing layer comprises a pigment layer containing the near-infrared absorbing pigment and an inorganic layer containing the inorganic material.

5. The filter as claimed in item 2 or 4 has the following characteristics: (a-1) the average transmittance of wavelengths from 440 nm to 500 nm at an incident angle of 0° is 75% or more; (a-2) the average transmittance of wavelengths from 500 nm to 600 nm at an incident angle of 0° is 75% or more; (a-3) when the transmittance of the infrared wavelength region at an incident angle of 0° is 50%, the difference between the wavelength on the short wavelength side and the wavelength on the long wavelength side is 35 nm or more; (a-4) the transmittance of wavelengths from 700 nm at an incident angle of 0° is 65% or less.

6. The filter of claim 1, wherein the near-infrared absorbing pigment is at least one selected from the group consisting of succinate compounds, phthalocyanine compounds, and anthocyanin compounds.

7. The filter of claim 6, wherein the above-mentioned squaric acid onium compound has the structure represented by the following formula (F1): [Chemical 1] wherein, The symbols in formula (F1) are as follows: R4 and R6 independently represent hydrogen atom, halogen atom, hydroxyl group, alkyl group with 1 to 20 carbon atoms, alkoxy group with 1 to 20 carbon atoms, aceoxy group with 1 to 10 carbon atoms, aryl group with 6 to 11 carbon atoms, alkylaryl group with 7 to 18 carbon atoms that may have substituents and may have oxygen atoms between carbon atoms, -NR7R8 (R7 and R8 independently represent hydrogen atom, alkyl group with 1 to 20 carbon atoms, -C(=O)-R9 (R9 is hydrogen atom, halogen atom, hydroxyl group, may have substituents and may contain unsaturated carbon atoms between carbon atoms) The following groups may be used: -NHR10, or -SO2-R10 (where R10 may be one or more hydrogen atoms that can be replaced by halogen atoms, hydroxyl groups, carboxyl groups, sulfonyl groups, or cyano groups and may contain unsaturated bonds, oxygen atoms, or saturated or unsaturated ring structures with carbon atoms in between) or groups represented by the following formula (S) (R41, R42 independently represent hydrogen atoms, halogen atoms, or alkyl groups with carbon atoms of 1 to 10 or alkoxy groups with carbon atoms of 1 to 10, and k is 2 or 3), [Chemical 2] R1 and R2, R2 and R5, and R1 and R3 may be linked together with nitrogen atoms to form heterocycles A, B, and C with a membership of 5 or 6.

8. The filter of claim 7, wherein the refractive index of the inorganic material at a wavelength of 500 nm is 1.38 to 2.

20.

9. The filter of claim 8, wherein the inorganic material is selected from at least one of the group consisting of silicon dioxide, aluminum oxide, and magnesium fluoride.

10. The filter of claim 9 has a protective layer on the surface of the first light-absorbing layer.

11. The filter of claim 10, wherein the protective layer disposed on the surface of the first light-absorbing layer comprises the same material as the inorganic material.

12. The filter of claim 11, wherein the protective layer disposed on the surface of the first light-absorbing layer has at least one of the optical properties of suppressing visible light reflection, reflecting ultraviolet light, and reflecting infrared light.

13. The filter of claim 12, wherein a second light-absorbing layer is provided on the first main surface side of the transparent substrate, and the second light-absorbing layer comprises an ultraviolet-absorbing pigment and a matrix material, wherein the ultraviolet-absorbing pigment has a maximum absorption wavelength at a wavelength of 300 nm to 430 nm.

14. The filter of claim 13, wherein the matrix material is selected from any one of the group consisting of silicon dioxide, aluminum oxide, magnesium fluoride, polyimide resin, polyester resin and polycarbonate resin.

15. The filter of claim 14, wherein the ultraviolet-absorbing pigment is selected from at least one of the group consisting of triazole compounds, indole compounds, methylimine compounds, benzotriazole compounds, anthocyanin compounds, and benzoazole compounds.

16. The filter of claim 15, wherein the ultraviolet-absorbing pigment comprises a cyanide compound represented by the following formula (U1): [Chemical 3] wherein, The symbols in formula (U1) are as follows: Y represents a methylene or oxygen atom substituted with R6 and R7; R1 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms that may have substituents; R2 to R7 independently represent a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 10 carbon atoms, respectively; X represents any of the divalent groups represented by the following formulas (X1) to (X5) (wherein, R8 and R9 independently represent monovalent hydrocarbon groups having 1 to 12 carbon atoms that may have substituents, and R10 to R19 independently represent a hydrogen atom, or a monovalent hydrocarbon group having 1 to 12 carbon atoms that may have substituents, respectively); [Chemical 4].

17. The filter of claim 16, wherein in formula (U1), R1, R8 and R9 are each independently hydrogen atoms and may be substituted with 1 to 6 carbon alkyl groups of cycloalkyl or phenyl groups, and R2 to R7 and R10 to R19 are each independently hydrogen atoms or 1 to 6 carbon alkyl groups.

18. The filter of claim 16, wherein in formula (U1), R1, R8 and R9 are each independently an alkyl group having 1 to 6 carbon atoms, and R2 to R7 and R10 to R19 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

19. The filter of claim 15, wherein the ultraviolet-absorbing dye is a benzoazole compound.

20. The filter of claim 19 has a protective layer on the surface of the second light-absorbing layer.

21. The filter of claim 20, wherein the protective layer on the surface of the second light-absorbing layer comprises the same material as the matrix material.

22. The filter of claim 21, wherein the protective layer on the surface of the second light-absorbing layer has at least one of the optical properties of suppressing visible light reflection, reflecting ultraviolet light, and reflecting infrared light.

23. The filter of claim 13 has the following characteristics: (b-1) It has a wavelength λUV50% in the ultraviolet wavelength region at an incident angle of light of 0° to 50°, wherein the wavelength λUV50% is in the range of 350 nm to 420 nm; (b-2) The difference between the wavelength λUV50% at an incident angle of light of 0° and the wavelength λUV50% at an incident angle of light of 30° is 10 nm or less; (b-3) The average transmittance of wavelengths from 440 nm to 500 nm at an incident angle of light of 0° is 75% or more; (b-4) The average transmittance of wavelengths from 500 nm to 600 nm at an incident angle of light of 0° is 75% or more. (b-5) Having a wavelength λIR50% in the infrared wavelength region that allows light transmittance of 50%, wherein the difference between the wavelength λIR50% at an incident angle of 0° and the wavelength λIR50% at an incident angle of 30° is 10 nm or less; (b-6) Having an average transmittance of 90% or less for wavelengths from 750 nm to 1000 nm at an incident angle of 0°; (b-7) Having a wavelength λIR20% in the infrared wavelength region that allows light transmittance of 20%, wherein the difference between the wavelength λIR20% at an incident angle of 0° and the wavelength λIR20% at an incident angle of 30° is 5 nm or less.

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