optical filter

Abstract

The present application relates to an optical filter having a substrate and a dielectric multilayer film laminated on at least one main surface side of the substrate and serving as an outermost layer, wherein the substrate contains a resin film containing a resin and a pigment (A) having a maximum absorption wavelength in the range of 730 nm to 800 nm in dichloromethane, and the pigment (A) satisfies specific spectral properties in the resin.

Description

Technical Field

[0001] This invention relates to a filter that transmits light in the visible wavelength range and blocks light in the near-infrared wavelength range. Background Technology

[0002] In imaging devices using solid-state imaging elements, filters are used to obtain clear images that reproduce tones well, while blocking light in the near-infrared wavelength range (hereinafter referred to as "near-infrared light").

[0003] Examples of such filters include: reflective filters that utilize the interference of light to reflect the light to be blocked, by alternately stacking dielectric films with different refractive indices (dielectric multilayers) on one or both sides of a transparent substrate; and reflective filters. However, filters with dielectric multilayers suffer from several problems because the optical thickness of the multilayer varies with the angle of incidence: changes in the spectral transmittance curve due to the angle of incidence; light leakage due to increased transmittance of near-infrared light at high angles of incidence, where high reflectivity is desirable; and noise caused by near-infrared light reflected from the multilayer. When using such filters, the spectral sensitivity of solid-state imaging elements may be affected by the angle of incidence. Therefore, a filter that blocks near-infrared light without significantly affecting visible light transmittance and without incident angle dependence is needed.

[0004] Here, patent documents 1 to 3 describe filters having a layer containing near-infrared absorbing pigments in order to reduce incident angle dependence.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2019 / 022069

[0008] Patent Document 2: International Publication No. 2019 / 168090

[0009] Patent Document 3: Japanese Patent Application Publication No. 2019-164269 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] However, in the filter described in Patent Document 1, there is room for improvement in near-infrared light blocking. In the filters described in Patent Documents 2 and 3, there is room for improvement in visible light transmittance.

[0012] Therefore, the object of the present invention is to provide a filter that, while maintaining high visible light transmittance, suppresses the reduction in near-infrared light blocking performance at high incident angles, such as light leakage.

[0013] means for solving problems

[0014] The present invention provides a filter having the following configuration.

[0015] [1] A filter having a substrate and a dielectric multilayer film laminated on at least one main surface side of the substrate as the outermost layer, wherein,

[0016] The substrate comprises a resin film, the resin film comprising resin and pigment (A), wherein pigment (A) has a maximum absorption wavelength in dichloromethane in the range of 730 nm to 800 nm, and

[0017] For the pigment (A), in the spectral transmittance curve of the coated film obtained by dissolving the pigment (A) in the resin and coating it onto an alkali glass plate in such a way that the transmittance at the maximum absorption wavelength is 10%, all of the following spectral characteristics (i-1) to (i-3) are satisfied:

[0018] (i-1) Average internal transmittance T in the wavelength range of 430 nm to 460 nm in the spectral transmittance curve 430-460(AVE) It is over 95%;

[0019] (i-2) Average internal transmittance T in the wavelength range of 460 nm to 530 nm in the spectral transmittance curve 460-530(AVE) It is over 97%;

[0020] (i-3) In the range of wavelengths above 600 nm, the absolute value of the difference between the shortest wavelength and the second shortest wavelength when the internal transmittance is 50% is above 125 nm.

[0021] Invention Effects

[0022] According to the present invention, a filter with high visible light transmittance and suppressing the reduction of near-infrared light blocking at high incident angles can be provided. Attached Figure Description

[0023] Figure 1 A cross-sectional view is shown schematically as an example of a filter according to one embodiment.

[0024] Figure 2 A cross-sectional view is shown to schematically illustrate another example of a filter according to one embodiment.

[0025] Figure 3A cross-sectional view is shown to schematically illustrate another example of a filter according to one embodiment.

[0026] Figure 4 A cross-sectional view is shown to schematically illustrate another example of a filter according to one embodiment.

[0027] Figure 5 The graph shows the spectral transmittance curves of the resin films in Examples 2-1, 2-7, and 2-12. Detailed Implementation

[0028] The embodiments of the present invention will be described below.

[0029] In this specification, near-infrared absorbing pigments are sometimes referred to as "NIR pigments" and ultraviolet absorbing pigments are sometimes referred to as "UV pigments".

[0030] In this specification, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas. Pigments containing compound (I) are also referred to as pigment (I), and the same applies to other pigments. Furthermore, groups represented by formula (I) are also referred to as group (I), and the same applies to groups represented by other formulas.

[0031] In this specification, internal transmittance refers to the transmittance obtained by subtracting the effect of interface reflection from the measured transmittance, expressed by the formula {measured transmittance / (100 - reflectance)} × 100.

[0032] In this specification, the transmittance of the substrate and the transmittance of the resin film containing pigments in the resin are all referred to as "internal transmittance" when they are described as such. On the other hand, the transmittance measured by dissolving the pigment in a solvent such as dichloromethane and the transmittance of the filter having a dielectric multilayer film are measured transmittance.

[0033] In this specification, for a specific wavelength range, transmittance of 90% or more means that the transmittance is not less than 90% over the entire wavelength range, i.e., the minimum transmittance over that wavelength range is 90% or more. Similarly, for a specific wavelength range, transmittance of 1% or less means that the transmittance is not greater than 1% over the entire wavelength range, i.e., the maximum transmittance over that wavelength range is 1% or less. The same applies to internal transmittance. The average transmittance and average internal transmittance over a specific wavelength range are the arithmetic mean of the transmittance and internal transmittance per 1 nm over that wavelength range.

[0034] In this specification, the "~" sign indicating a numerical range includes both the upper and lower limits.

[0035] <Filter>

[0036] A filter according to one embodiment of the present invention (hereinafter also referred to as "the filter") has a substrate and a dielectric multilayer film laminated on at least one main surface side of the substrate and serving as the outermost layer.

[0037] The configuration example of this filter will be described using the accompanying drawings. Figures 1-4 A cross-sectional view is shown schematically as an example of a filter according to one embodiment.

[0038] Figure 1 The filter 1A shown is an example of having a dielectric multilayer film 30 on one main surface side of the substrate 10. It should be noted that "having a specific layer on the main surface side of the substrate" is not limited to having the layer in contact with the main surface of the substrate, but also includes having other functional layers between the substrate and the layer.

[0039] Figure 2 The filter 1B shown is an example of having a dielectric multilayer film 30 on both main surfaces of the substrate 10.

[0040] Figure 3 The filter 1C shown is an example of a substrate 10 having a support 11 and a resin film 12 laminated on one main side of the support 11. The filter 1C also has a dielectric multilayer film 30 on the resin film 12 and on the main side of the unlaminated resin film 12 on the support 11.

[0041] Figure 4 The filter 1D shown is an example of a substrate 10 having a support 11 and resin films 12 laminated on two main surfaces of the support 11. The filter 1D also has a dielectric multilayer film 30 on each resin film 12.

[0042] <Substrate>

[0043] In the filter of the present invention, the substrate comprises a resin film containing resin and a pigment (A), wherein the pigment (A) has a maximum absorption wavelength in dichloromethane in the range of 730 nm to 800 nm. The pigment (A) is a near-infrared (NIR) absorbing pigment. By having a substrate containing a resin film comprising a near-infrared absorbing pigment, the absorption characteristics of the substrate can be utilized to suppress the degradation of the spectral characteristics of the dielectric multilayer film at high incident angles, such as light leakage and noise in the near-infrared region.

[0044] <Pigment (A)>

[0045] The pigment (A) satisfies specific spectral characteristics in the resin used as the substrate. Specifically, in the spectral transmittance curve of the coated film obtained by dissolving the pigment (A) in the resin in such a way that the transmittance at the maximum absorption wavelength is 10%, all of the following spectral characteristics (i-1) to (i-3) are satisfied.

[0046] (i-1) Average internal transmittance T in the wavelength range of 430 nm to 460 nm in the spectral transmittance curve 430-460(AVE) It is over 95%;

[0047] (i-2) Average internal transmittance T in the wavelength range of 460 nm to 530 nm in the spectral transmittance curve 460-530(AVE) It is over 97%;

[0048] (i-3) In the range of wavelengths above 600 nm, the absolute value of the difference between the shortest wavelength and the second shortest wavelength when the internal transmittance is 50% is above 125 nm.

[0049] This filter, containing a pigment (A) that satisfies all of the above spectral characteristics, is a filter with high visible light transmittance and suppresses the reduction of near-infrared light blocking at high incident angles by absorbing near-infrared light over a wide range.

[0050] By satisfying the spectral characteristics (i-1), it is possible to obtain a filter with excellent transmittance of visible light, especially blue light.

[0051] The spectral characteristics (i-1) are preferably 96% or higher.

[0052] By satisfying the spectral characteristics (i-2), it is possible to obtain filters with excellent transmittance of visible light, especially green light.

[0053] The spectral characteristics (i-2) are preferably above 98%.

[0054] By satisfying the spectral characteristics (i-3), a filter that absorbs near-infrared light over a wide wavelength range can be obtained. This effectively prevents light leakage in wavelengths where multilayer films cannot completely block light at high incident angles, leading to leakage. To absorb light over a wide wavelength range, combining multiple pigments with different maximum absorption wavelengths can be considered. However, while combining multiple NIR pigments can block near-infrared light over a wide range, it also tends to decrease transmittance in the visible light region. Because pigment (A) itself exhibits wide-range absorption characteristics in the resin, even without combining multiple NIR pigments, it is possible to effectively block near-infrared light using only pigment (A) while maintaining good transmittance in the visible light region.

[0055] The absolute value in the spectral characteristics (i-3) is preferably 128 nm or more, and more preferably 130 nm or more.

[0056] As pigments (A), examples include: anthocyanins, squaric acid... From the viewpoint that salt pigments, phthalocyanine pigments, ammonium pigments, and diammonium pigments easily satisfy the above-mentioned spectral characteristics (i-1) to (i-3), anthocyanin pigments are preferred.

[0057] As anthocyanin, compounds represented by the following formula (A) are particularly preferred.

[0058]

[0059] The symbols in equation (A) are as follows.

[0060] R 1 ~R 7 Each of the following groups can be independently a hydrogen atom, a halogen atom, a sulfonyl group, a hydroxyl group, a cyano group, a nitro group, a carboxyl group, a phosphate group, an alkyl group having 1 to 10 carbon atoms that may have a substituent, an alkoxy group having 1 to 10 carbon atoms that may have a substituent, or an acyloxy group having 1 to 10 carbon atoms that may have a substituent.

[0061] In equation (A), R 1 ~R 7 The left and right sides of the formula can be the same or different, but it is preferred that they are all the same.

[0062] Examples of substituents that can be alkyl groups having 1 to 10 carbon atoms, alkoxy groups having 1 to 10 carbon atoms, or acyloxy groups having 1 to 10 carbon atoms include halogen atoms or alkoxy groups having 1 to 10 carbon atoms.

[0063] In this specification, unless otherwise stated, alkyl groups can be straight-chain, branched, cyclic, or combinations thereof. The same applies to alkyl groups containing alkoxy groups. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine, with fluorine and chlorine atoms being preferred.

[0064] Considering factors such as ease of synthesis, R 1 Each atom is preferably a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an acyloxy group having 1 to 10 carbon atoms, and is particularly preferred to be a hydrogen atom.

[0065] R 2 ~R 7 Each of the following is preferably composed of a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms that may have substituents, an alkoxy group having 1 to 10 carbon atoms that may have substituents, or an acyloxy group having 1 to 10 carbon atoms that may have substituents. From the viewpoint of ease of synthesis, R... 2 ~R 7Each is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms that may have a substituent.

[0066] From the viewpoint of solubility in transparent resins or solvents, R 6 ~R 7 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 fewer carbon atoms, and even more preferably tert-butyl, isopropyl, or isobutyl.

[0067] R 2 ~R 5 R 6 ~R 7 Two adjacent groups in a ring can connect to each other to form a five-membered to an eight-membered ring. The ring can be aliphatic or aromatic.

[0068] Formula (A) optionally has Z. Z is a five-membered ring or a six-membered ring. It is preferred from the viewpoint of durability when Formula (A) has Z. It should be noted that the hydrogen atom bonded to the carbon atom constituting Z can be replaced by an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms.

[0069] In this specification, unless otherwise stated, aryl refers to a group bonded via carbon atoms of an aromatic ring, such as a benzene ring, naphthalene ring, biphenyl ring, furan ring, thiophene ring, pyrrole ring, etc., which constitute an aromatic compound.

[0070] X - It represents a monovalent anion.

[0071] X - PF6 is preferred. - [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.

[0072] By using an anionic structure, a pigment compound (A) with excellent lightfastness can be obtained.

[0073] R 8 Represents a hydrogen atom, a halogen atom, or -Y 5 -R 10 (Y 5 The bonds are single bonds, ether bonds (-O-), sulfonyl bonds (-SO2-), ester bonds (-C(=O)-O- or -OC(=O)-), or urea bonds (-NH-C(=O)-NH-), R 10It can be an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms (which may have substituents).

[0074] R 8 Preferably, hydrogen atoms, halogen atoms, and Y atoms are used. 5 -Y for single bond 5 -R 10 More preferably, it is 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 that can be substituted by a halogen atom.

[0075] In formula (A), more specifically, compounds in which the atoms or groups bonded to the respective skeletons are shown in the table below can be listed. Of all the compounds shown in the table below, R... 1 ~R 7 The left and right sides of the expression are identical.

[0076] Table 1

[0077]

[0078] Pigment (A), for example, can be obtained as R 1 ~R 5 R 7 It is a hydrogen atom and X - BF4 - The synthesis of pigment (A1) is carried out as shown in the flowchart.

[0079]

[0080] (1) Make salicylaldehyde (a) and R 6 The alkyne compound (b) with the group reacts to give compound (c).

[0081] (2) Compound (d) is obtained by reacting compound (c) with 4-dimethylaminopyridine.

[0082] (3) Compound (e) is obtained by reacting compound (d) with methylmagnesium bromide and tetrafluoroboric acid.

[0083] (4) By reacting compound (e) with R 8 The pigment (A1) is obtained by reacting the aldehyde diphenylamine hydrochloride (f) of the group.

[0084] In X - For PF6 - In the case of X, the synthesis can be carried out by using hexafluorophosphate instead of tetrafluoroboric acid in step (3) above. - [Rf-SO2] -In this case, synthesis can be carried out by using Rf-SO3H instead of tetrafluoroboric acid in step (3) above, where X is [N(Rf-SO2)2]. - In this case, the synthesis can be carried out by using NH(Rf-SO2)2 instead of tetrafluoroboric acid in step (3) above.

[0085] The resin film may contain only one pigment (A) or a combination of two or more pigments (A).

[0086] From the viewpoint of the spectral characteristics of the resin membrane and Tg and the solubility of pigment (A) in the resin membrane, the content of pigment (A) in the resin membrane is preferably 0.1 to 15 parts by mass relative to 100 parts by mass of resin, more preferably 0.5 to 10 parts by mass.

[0087] <Pigment (B)>

[0088] In this filter, the resin film preferably further comprises a pigment (B), which has a maximum absorption wavelength in dichloromethane in the range of 650 nm to 730 nm. Like pigment (A), pigment (B) is also a near-infrared (NIR) absorbing pigment. This allows for more effective blocking of near-infrared light.

[0089] When the resin film contains pigment (A) and pigment (B), the resin film preferably satisfies all of the following spectral characteristics (ii-1) to (ii-4).

[0090] (ii-1) When the content of pigment (A) in the resin film is set as [A] (mass%) and the content of pigment (B) is set as [B] (mass%),

[0091] [A] / [B]<0.85;

[0092] (ii-2) Internal transmittance T at a wavelength of 700 nm 700 Less than 5%;

[0093] (ii-3) Average internal transmittance T in the wavelength range of 730 nm to 800 nm in the spectral transmittance curve 730-800(AVE) Below 25%;

[0094] (ii-4) Average internal transmittance T in the wavelength range of 430 nm to 460 nm in the spectral transmittance curve 430-460(AVE) It is over 92%.

[0095] By satisfying the spectral characteristics (ii-1), it means that the pigment (A) can absorb near-infrared light over a wide range, so even if the content of pigment (A) is low, it can sufficiently block light near the maximum absorption wavelength of pigment (A).

[0096] The spectral characteristics (ii-1) are more preferably [A] / [B]<0.75, and even more preferably 0.05<[A] / [B].

[0097] By satisfying the spectral characteristics (ii-2), it means that the near-infrared light is highly blocked.

[0098] The spectral characteristics (ii-2) are more preferably 4% or less.

[0099] By satisfying the spectral characteristics (ii-3), it means that the near-infrared light blocking is high.

[0100] The spectral characteristics (ii-3) are more preferably 24% or less.

[0101] By satisfying the spectral characteristics (ii-4), it means that the blue light transmittance is high.

[0102] The spectral characteristics (ii-4) are more preferably 92.5% or higher.

[0103] As pigment (B), styracocyanidin is preferred. At least one of the group consisting of salt pigments, anthocyanins, phthalocyanine pigments, ammonium pigments, and diammonium pigments, particularly preferably squaric acid. Salt pigment.

[0104] As a squaric acid Salt pigments, preferably compounds represented by the following formula (I).

[0105]

[0106] The symbols in equation (I) are as follows.

[0107] R 24 and R 26 Each of the following can be independently represented: hydrogen atom, halogen atom, hydroxyl group, alkyl group with 1 to 6 carbon atoms or alkoxy group with 1 to 6 carbon atoms, acyloxy group with 1 to 10 carbon atoms, -NR. 27 R 28 (R 27 and R 28 Each independently represents a hydrogen atom, an alkyl group with 1 to 20 carbon atoms, or a -C(=O)-R group. 29 (R 29 (Hydrogen atom, alkyl group with 1 to 20 carbon atoms that may have substituents, or aryl group with 6 to 11 carbon atoms that may have substituents, or aralkyl group with 7 to 18 carbon atoms that may have substituents and may have oxygen atoms between carbon atoms), -NHR 30 or -SO2-R 30 (R 30Each of the groups consisting of one or more hydrogen atoms may be substituted with halogen atoms, hydroxyl groups, carboxyl groups, sulfonyl groups, or cyano groups, and may contain unsaturated bonds, oxygen atoms, saturated or unsaturated ring structures of 1 to 25 carbon atoms (hydrocarbon groups), or groups represented by the following formula (S) (R). 41 R 42 Independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. (k is 2 or 3).

[0108]

[0109] R 21 and R 22 R 22 and R 25 and R 21 and R 23 They can connect with each other and together with nitrogen atoms to form 5-membered or 6-membered heterocycles A, B, and C, respectively.

[0110] For R in the case of forming heterocyclic A 21 and R 22 As for R 21 and R 22 The bonded divalent group -Q- indicates that the hydrogen atom can be substituted by an alkyl group with 1 to 6 carbon atoms, an aryl group with 6 to 10 carbon atoms, or an alkylene group with 1 to 10 carbon atoms that can have a substituent, or a hydrogen atom can be substituted by an alkyl group with 1 to 6 carbon atoms, an aryl group with 6 to 10 carbon atoms, or an alkylene group with 1 to 10 carbon atoms that can have a substituent.

[0111] For R in the case of forming heterocyclic B 22 and R 25 And R in the case of forming heterocyclic C 21 and R 23 As for R 22 and R 25 The bonded divalent group -X 1 -Y 1 -and R 21 and R 23 The bonded divalent group -X 2 -Y 2 -(The side bonded to nitrogen is X) 1 and X 2 ), X 1 and X 2 Each is a group represented by the following formula (1x) or (2x), Y 1 and Y 2 Each is a group selected from any of the following formulas (1y) to (5y). In X1 and X 2 When each of the groups is represented by the following formula (2x), Y 1 and Y 2 Each can be a single bond, and in this case, there can be oxygen atoms between carbon atoms.

[0112]

[0113] In formula (1x), each of the four Zs independently represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, or -NR. 38 R 39 (R 38 and R 39 Each of the following independently represents an alkyl group having 1 to 20 hydrogen 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 It represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms.

[0114] R 27 R 28 R 29 R 31 ~R 37 R without the formation of heterocycles 21 ~R 23 and R 25 Each can bond with any of the other members to form a 5-membered ring or a 6-membered ring. R 31 and R 36 Direct bonding is possible, R 31 and R 37 They can be bonded directly.

[0115] R without the formation of heterocycles 21 and R 22 Each can independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms that may have substituents, an allyl group having 6 to 11 carbon atoms that may have substituents, or an aryl group having 6 to 11 carbon atoms that may have substituents. R in the case where a heterocycle is not formed. 23 and R 25 Each can be independently represented by a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0116] Compound (I) can be manufactured, for example, by known methods described in U.S. Patent No. 5,543,086, U.S. Patent Application Publication No. 2014 / 0061505, and International Publication No. 2014 / 088063.

[0117] The resin film may contain only one pigment (B) or a combination of two or more pigments (B).

[0118] The content of pigment (B) in the resin film is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 10 parts by weight, relative to 100 parts by weight of resin.

[0119] <Other Pigments>

[0120] Resin films may contain other pigments besides NIR pigments, such as UV pigments.

[0121] Regarding UV pigments, the following can be listed: Zazoles, anthocyanins, naphthalenedicarboximides, diazoles, Azides Examples of UV dyes include azole alkyl groups, naphthalenedicarboxylic acid groups, styryl groups, anthracene groups, cyclic carbonyl groups, and triazole groups. Furthermore, UV dyes can be used alone or in combination with two or more types.

[0122] <Substrate Composition>

[0123] The substrate in this filter can be a single-layer structure or a multi-layer structure. Furthermore, the material used as the substrate can be any transparent material that transmits visible light in the range of 400nm to 700nm; it can be organic or inorganic, without any particular restrictions.

[0124] When the substrate has a single-layer structure, a resin substrate composed of a resin film containing resin and NIR pigment (A) is preferred.

[0125] When the substrate has a multilayer structure, it is preferable to have a composite substrate in which a resin film containing NIR pigment (A) is laminated on at least one main surface of the support. In this case, the support preferably contains a transparent resin or a transparent inorganic material.

[0126] There are no restrictions on the type of resin used, as long as it is a transparent resin. One or more transparent resins selected from polyester resins, acrylic resins, epoxy resins, olefin-thiol resins, polycarbonate resins, polyether resins, polyaryl ester resins, polysulfone resins, polyethersulfone resins, poly(p-phenylene) resins, polyaryl ether phosphine oxide resins, polyamide resins, polyimide resins, polyamide-imide resins, polyolefin resins, cycloolefin resins, polyurethane resins, and polystyrene resins can be used. These resins can be used alone or in combination of two or more.

[0127] From the viewpoints of the spectral characteristics, glass transition temperature (Tg), and adhesion of the resin film, it is preferable to select one or more resins selected from polyimide resin, polycarbonate resin, polyester resin, and acrylic resin.

[0128] When the substrate contains NIR pigment (B) or other pigments, these pigments may be contained in a resin film containing NIR pigment (A), or they may be contained in other resin films.

[0129] As a transparent inorganic material, glass or crystalline materials are preferred.

[0130] Examples of glasses suitable for use as supports include: absorbing glasses containing copper ions (near-infrared absorbing glasses), such as fluorophosphate glasses or phosphate glasses; soda-lime glass; borosilicate glass; alkali-free glass; and quartz glass. Depending on the purpose, absorbing glasses are preferred; from the viewpoint of absorbing infrared light, phosphate glasses and fluorophosphate glasses are preferred. When it is desired to absorb a large amount of red light (600nm–700nm), alkali glass, alkali-free glass, and quartz glass are preferred. It should be noted that "phosphate glass" also includes silicate phosphate glasses in which a portion of the glass framework is composed of SiO2.

[0131] As a glass, chemically strengthened glass can be used, which is obtained by replacing alkali metal ions with small ionic radii (e.g., Li ions, Na ions) present on the main surface of the glass plate with alkali metal ions with larger ionic radii (e.g., Na ions or K ions for Li ions, and K ions for Na ions) through ion exchange at a temperature below the glass transition temperature.

[0132] Examples of crystalline materials that can be used as supports include: quartz, lithium niobate, sapphire, and other birefringent crystals.

[0133] As a support, inorganic materials are preferred from the perspective of shape stability related to long-term reliability of spectral and mechanical properties, and from the perspective of processability during filter manufacturing. Glass and sapphire are particularly preferred.

[0134] The resin film can be formed by dissolving or dispersing a pigment (A), resin or resin raw material components, and other components to be formulated as needed, in a solvent to prepare a coating solution; applying the coating solution onto a support and drying it; and further curing it as needed. The support can be the support contained in this filter, or it can be a peelable support used only during the formation of the resin film. Furthermore, the solvent can be any dispersion medium that can be stably dispersed or a solvent that can dissolve the resin.

[0135] Furthermore, to improve voids caused by microbubbles, depressions caused by the adhesion of foreign matter, and pinholes during the drying process, the coating liquid may contain surfactants. Additionally, methods such as dip coating, cast coating, or spin coating can be used when applying the coating liquid. The coating liquid is applied to a support and then dried to form a resin film. Furthermore, if the coating liquid contains transparent resin components, further curing treatments such as thermosetting or photocuring are performed.

[0136] Alternatively, the resin film can also be formed into a film shape by extrusion molding. When the substrate is a single-layer structure (resin substrate) consisting of a resin film containing pigment (A), the resin film can be used directly as the substrate. When the substrate is a multilayer structure (composite substrate) having a support and a resin film containing pigment (A) laminated on at least one main surface of the support, the substrate can be manufactured by laminating the film onto the support and integrating it using methods such as hot pressing.

[0137] A filter may contain one layer of resin film or two or more layers of resin film. When there are two or more layers of resin film, each layer may have the same composition or different compositions.

[0138] The thickness of the resin film is preferably 0.3 μm to 20 μm. The filter of the present invention, by containing an NIR pigment (A) in the resin that satisfies specific spectral characteristics, can effectively block near-infrared light over a wide range, even with a low pigment content. Therefore, the resin film containing the pigment (A) can be made thinner. It should be noted that when the resin film comprises multiple layers, the total thickness of each layer is preferably 0.6 μm to 40 μm.

[0139] In addition, when the substrate is a single-layer structure (resin substrate) composed of a resin film containing pigment (A), the thickness of the resin film is preferably 50 μm to 150 μm.

[0140] When the substrate is a multilayer structure (composite substrate) having a support and a resin film containing pigment (A) laminated on at least one main surface of the support, the thickness of the resin film is preferably 0.3 μm to 20 μm.

[0141] There are no particular restrictions on the shape of the substrate; it can be in the form of a block, plate, or film.

[0142] Furthermore, from the viewpoint of reducing warpage and lowering the height of optical elements when forming a dielectric multilayer film, the thickness of the substrate is preferably 300 μm or less. When the substrate is a resin substrate composed of a resin film, the thickness of the substrate is preferably 50 μm to 300 μm. When the substrate is a composite substrate having a support and a resin film, the thickness of the substrate is preferably 100 μm to 300 μm.

[0143] <Dielectric Multilayer Film>

[0144] In this filter, a dielectric multilayer film is stacked on at least one main surface side of the substrate and serves as the outermost layer.

[0145] 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). The other dielectric multilayer film is preferably designed as an NIR reflective layer, a reflective layer having a reflective region other than the near-infrared region, or an anti-reflective layer.

[0146] A NIR reflective layer is a dielectric multilayer film designed to block light in the near-infrared region. For example, an NIR reflective layer may transmit visible light and primarily reflect light in the near-infrared region, excluding the light-blocking region of the resin film acting as an absorption layer. It should be noted that the reflective region of the NIR reflective layer may also include the light-blocking region of the resin film in the near-infrared region. The NIR reflective layer may also be appropriately designed to block light in wavelength ranges other than the near-infrared region, such as near-ultraviolet light, in addition to its NIR reflective properties.

[0147] The NIR reflective layer is, for example, composed of a dielectric multilayer film obtained by alternating layers of a low-refractive-index dielectric film (low-refractive-index film) and a high-refractive-index dielectric film (high-refractive-index film). The refractive index of the high-refractive-index film is preferably 1.6 or higher, 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 from the viewpoints of film formation properties, reproducibility of refractive index, and stability.

[0148] On the other hand, the refractive index of the low-refractive-index film is preferably less than 1.6, more preferably greater than or equal to 1.45 and less than 1.55. Examples of materials that can be used for low-refractive-index films include SiO2 and SiO2. x N y From the perspectives of film-forming reproducibility, stability, and economy, SiO2 is preferred.

[0149] The NIR reflector is preferably designed to satisfy all of the following conditions (iv-1) to (iv-4) in the spectral transmittance curves at incident angles of 0 degrees and 30 degrees.

[0150] (iv-1) The wavelength at which the transmittance is 50% is in the range of 600 nm to 850 nm.

[0151] (iv-2) The wavelength at which the transmittance is 50% is in the wavelength range of 385nm to 425nm;

[0152] (iv-3) The average transmittance of light in the wavelength range of 435nm to 650nm is over 88%;

[0153] (iv-4) The average transmittance of light in the wavelength range of 750nm to 1000nm is less than 10%.

[0154] Furthermore, the transmittance of the NIR reflective layer preferably changes steeply within the boundary wavelength range between the transmission region and the light-blocking region. For this purpose, the total number of layers in the dielectric multilayer film constituting the reflective layer is preferably 15 or more, more preferably 25 or more, and even more preferably 30 or more. However, when the total number of layers increases, warping or an increase in film thickness may occur; therefore, the total number of layers is preferably 100 or less, more preferably 75 or less, and even more preferably 60 or less. Additionally, the overall film thickness of the reflective layer is preferably 2 μm to 10 μm.

[0155] If the total number of layers and the film thickness of the dielectric multilayer film are within the above range, the NIR reflective layer meets the requirements for miniaturization and can suppress incident angle dependence while maintaining high productivity. Furthermore, in the formation of the dielectric multilayer film, vacuum film deposition processes such as CVD, sputtering, and vacuum evaporation can be used; wet film deposition processes such as spraying and immersion can also be used.

[0156] A specific spectral characteristic can be imparted using a single NIR reflective layer (a set of dielectric multilayer films), or it can be imparted using two or more NIR reflective layers. When there are two or more NIR reflective layers, each reflective layer can have the same or different configurations. Typically, multiple reflective layers with different reflection bands are used. In the case of two reflective layers, one layer can be a near-infrared reflective layer that blocks short-wavelength light in the near-infrared region, and the other layer can be a near-infrared / near-ultraviolet reflective layer that blocks both long-wavelength and near-ultraviolet light in the near-infrared region.

[0157] Examples of antireflective layers include: multilayer dielectric films, intermediate refractive index media, and moth-eye structures with gradually changing refractive index. Among these, multilayer dielectric films are preferred from the perspective of optical efficiency and productivity. Like reflective layers, antireflective layers are obtained by alternately stacking dielectric films.

[0158] <Filter>

[0159] The filter of the present invention preferably satisfies all of the following spectral characteristics (iii-1) to (iii-3) by adopting the above-described configuration.

[0160] (iii-1) The maximum transmittance T in the wavelength range of 730 nm to 800 nm in the spectral transmittance curve at an incident angle of 60 degrees. 730-800(60°)(MAX)Below 1.5%;

[0161] (iii-2) Average transmittance T in the wavelength range of 435 nm to 480 nm in the spectral transmittance curve with an incident angle of 0 degrees. 435-480(0°)(AVE) It is over 85%;

[0162] (iii-3) Average transmittance T in the wavelength range of 435 nm to 480 nm in the spectral transmittance curve with an incident angle of 30 degrees. 435-480(30°)(AVE) It is over 85%.

[0163] By satisfying the spectral characteristics (iii-1), it is possible to obtain a filter with high blocking properties for near-infrared light, which does not leak light even at high incident angles.

[0164] The spectral characteristics (iii-1) are more preferably 1.0% or less.

[0165] By satisfying the spectral characteristics (iii-2), a filter with excellent blue light transmittance can be obtained.

[0166] The spectral characteristics (iii-2) are more preferably 89% or higher.

[0167] By satisfying the spectral characteristics (iii-3), it is possible to obtain a filter that exhibits excellent blue light transmittance even at high incident angles.

[0168] The spectral characteristics (iii-3) are more preferably 89% or higher.

[0169] This filter can have, for example, constituent elements (layers) that impart absorption by inorganic microparticles that control the transmission and absorption of light within a specific wavelength range. Specific examples of inorganic microparticles include: ITO (indium tin oxide), ATO (antimony-doped tin oxide), cesium tungstate, and lanthanum boride. ITO microparticles and cesium tungstate microparticles have high visible light transmittance and exhibit light absorption over a wide range of infrared wavelengths greater than 1200 nm, thus enabling their use in applications requiring infrared light blocking.

[0170] This filter, for example, can provide an imaging device with excellent color reproduction when used in imaging devices such as digital cameras. An imaging device using this filter includes a solid-state imaging element, an imaging lens, and the filter itself. This 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.

[0171] Example

[0172] The invention will now be described in more detail through examples.

[0173] The various spectral characteristics were measured using a UV-Vis spectrophotometer (manufactured by Hitachi High Technology Co., Ltd., model UH-4150).

[0174] It should be noted that the spectral characteristics, unless otherwise specified, are values ​​measured at an incident angle of 0 degrees (perpendicular to the main surface of the filter).

[0175] The pigments used in each example are described below.

[0176] Compounds 1, 2, and 3: synthesized using the methods described later.

[0177] Compound 4: synthesized based on Dyes and pigments 73 (2007) 344-352.

[0178] Compound 5: Synthesized based on International Publication No. 2019 / 168090.

[0179] Compound 6: Manufactured by FEW Chemicals, product name S2137

[0180] Compound 7: Synthesized based on Japanese Patent Application Publication No. 2019-164269

[0181] Compound 8: Phthalocyanine manufactured by Yamada Chemical Co., Ltd., trade name: FDR-026

[0182] Compound 9: Synthesis based on International Publication No. 2017 / 135359

[0183] Compound 10: synthesized based on Japanese Patent No. 6358114.

[0184] Compound 11: synthesized based on U.S. Patent Application Publication No. 2014 / 0061505 and International Publication No. 2014 / 088063.

[0185] Compound 12: synthesized based on the specification in U.S. Patent No. 5,543,086.

[0186] Compound 1

[0187] Compound 2

[0188] Compound 3

[0189] Compound 4

[0190] Compound 5

[0191] Compound 6

[0192] Compound 7

[0193] The structure of compound 8 is unknown.

[0194] Compound 9

[0195] Compound 10

[0196] Compound 11

[0197] Compound 12

[0198] <Synthesis of Compound 1>

[0199]

[0200] <Step 1>

[0201] 3,3-Dimethyl-1-butyne (13 g, 160 mmol) and tetrahydrofuran (40 mL) were added to a 1 L flask, cooled to -78 °C and stirred. Butyllithium (1.6 M, 100 mL in hexane) was added dropwise, and the mixture was stirred at -78 °C for 1 hour. Then, salicylaldehyde (10 g, 82 mmol) dissolved in tetrahydrofuran (80 mL) was added, and the mixture was stirred at room temperature for 3 hours. After the reaction was complete, the mixture was quenched with a saturated aqueous ammonium chloride solution and extracted with ethyl acetate. The solvent was removed, and then manganese dioxide (35 g, 400 mmol) and acetone (80 mL) were added, and the mixture was stirred at room temperature for 16 hours. After the reaction was complete, the solvent in the filtrate was removed by filtration, and the filtrate was purified by column chromatography to give 6.1 g (37%) of intermediate (c1).

[0202] <Step 2>

[0203] Intermediate (c1) (6.1 g, 30 mmol) and N,N-dimethylformamide (120 mL) were added to a 500 mL round-bottom flask. The mixture was cooled to 0 °C and stirred. 4-Dimethylaminopyridine (0.37 g, 3.0 mmol) was added, and the reaction was carried out at room temperature for 16 hours. After the reaction was completed, water was added to quench the reaction, and the solvent was removed by extraction with ethyl acetate. The solution was then purified by column chromatography to obtain 4.2 g (70%) of intermediate (d1).

[0204] <Step 3>

[0205] Intermediate 2 (4.2 g, 21 mmol) and tetrahydrofuran (50 mL) were added to a 500 mL pear-shaped flask, cooled to 0 °C and stirred. Methylmagnesium bromide (1 M, 30 mL in tetrahydrofuran) was added dropwise, and the mixture was allowed to react at room temperature for 5 hours. After the reaction was complete, ice water was added to quench the reaction, followed by the addition of 150 mL of a 42% aqueous solution of tetrafluoroboric acid, and the mixture was stirred at room temperature for 30 minutes. The solvent was removed by extraction with dichloromethane, and the precipitated solid was then washed with ethyl acetate to obtain 4.4 g (77%) of intermediate (e1).

[0206] <Step 4>

[0207] In a 500 mL flask, intermediate (e1) (4.4 g, 15 mmol), malondialdehyde diphenylamine hydrochloride (1.9 g, 7.5 mmol), sodium acetate (3.0 g, 36 mmol), acetic acid (60 mL), and acetic anhydride (60 mL) were added and stirred at 80 °C for 2 hours. After the reaction was complete, water was added, the mixture was filtered, and the precipitated solid was recovered and purified by column chromatography to obtain 1.9 g (50%) of compound 1.

[0208] <Synthesis of Compound 2>

[0209]

[0210] <Step 1>

[0211] In a 500 mL flask, intermediate (d1) (5.0 g, 25 mmol), obtained by the same synthetic method as compound 1, was added, followed by 60 mL of tetrahydrofuran. The mixture was cooled to 0 °C and stirred. Magnesium methyl bromide (1 M, 37 mL in tetrahydrofuran) was added dropwise, and the mixture was allowed to react at room temperature for 5 hours. After the reaction was complete, ice water was added to quench the reaction, followed by 150 mL of a 60% aqueous solution of hexafluorophosphate. The mixture was stirred at room temperature for 30 minutes. The solvent was removed by extraction with dichloromethane, and the precipitated solid was washed with ethyl acetate to give 7.2 g (84%) of intermediate (e2).

[0212] <Step 2>

[0213] In a 500 mL flask, intermediate (e2) (5.2 g, 15 mmol), malondialdehyde diphenylamine hydrochloride (1.9 g, 7.5 mmol), sodium acetate (3.0 g, 36 mmol), acetic acid (60 mL), and acetic anhydride (60 mL) were added and stirred at 80 °C for 2 hours. After the reaction was complete, water was added, the mixture was filtered, and the precipitated solid was recovered and purified by column chromatography to obtain 1.8 g (41%) of compound 2.

[0214] <Synthesis of Compound 3>

[0215]

[0216] <Step 1>

[0217] In a 500 mL flask, intermediate (d1) (3.0 g, 15 mmol), obtained by the same synthetic method as compound 1, was added, followed by tetrahydrofuran (36 mL). The mixture was cooled to 0 °C and stirred. Magnesium methyl bromide (1 M, 22 mL in tetrahydrofuran) was added dropwise, and the mixture was allowed to react at room temperature for 5 hours. After the reaction was complete, ice water was added to quench the reaction, followed by the addition of a 10% aqueous solution of bis(trifluoromethanesulfonyl)imide (100 mL), and the mixture was stirred at room temperature for 30 minutes. The solvent was removed by extraction with dichloromethane, and the precipitated solid was washed with ethyl acetate to give 5.3 g (75%) of intermediate (e3).

[0218] <Step 2>

[0219] In a 500 mL flask, intermediate (e3) (5.3 g, 11 mmol), malondialdehyde diphenylamine hydrochloride (1.4 g, 5.3 mmol), sodium acetate (2.1 g, 26 mmol), acetic acid (50 mL), and acetic anhydride (50 mL) were added and stirred at 80 °C for 2 hours. After the reaction was complete, water was added, the mixture was filtered, and the precipitated solid was recovered and purified by column chromatography to obtain 1.6 g (42%) of compound 3.

[0220] <Spectroscopic characteristics of pigment (A) in resin>

[0221] <Example 1-1~Example 1-10>

[0222] The 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% by mass.

[0223] The NIR pigment compounds shown in the table below were added to the polyimide resin solution prepared above, such that the ratio of NIR pigment compound to resin was 6 parts by mass relative to 100 parts by mass, and the solution was heated at 50°C while stirring for 2 hours. The pigment-containing resin solution was coated onto a glass substrate (alkali glass, D263 manufactured by Schott AG) and dried to obtain a resin film (coated film) with a thickness of 1 μm.

[0224] The internal spectral transmittance curve was calculated using the spectral transmittance and spectral reflectance curves of the glass substrate with the resin film, and normalized to such that the internal transmittance at the maximum absorption wavelength is 10%.

[0225] The spectral characteristics are shown in the table below.

[0226] It should be noted that Examples 1-1 to 1-3 are examples, and Examples 1-4 to 1-10 are comparative examples.

[0227] 50%-50% absorption width: The absolute value (nm) of the difference between the shortest wavelength and the second shortest wavelength when the internal transmittance is 50% in the wavelength range above 600nm.

[0228]

[0229] Compared with compounds 4 to 10, as shown in Examples 1-1 to 1-3, compounds 1 to 3 maintain high transmittance of blue and green light in the spectrum of the resin and exhibit a wide range of absorption characteristics in the near-infrared range.

[0230] <Spectral properties of resin films>

[0231] <Example 2-1~Example 2-12>

[0232] 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% by mass. NIR pigments (A) and (B) as shown in the table below were added to the resin solution such that the amounts (parts by mass) of resin, NIR pigment (A), and NIR pigment (B) relative to 100 parts by mass are as shown in the table below, and the mixture was heated at 50°C while stirring for 2 hours. The pigment-containing resin solution was coated onto a glass substrate (alkali glass, D263 manufactured by Schott AG) and dried to obtain a resin film with a thickness of 1 μm.

[0233] The internal spectral transmittance curve was calculated using the spectral transmittance and spectral reflectance curves of the glass substrate with the resin film, and normalized to such that the internal transmittance at the maximum absorption wavelength is 10%.

[0234] The spectral characteristics are shown in the table below.

[0235] In addition, the spectral transmittance curves of the resin films of Examples 2-1, 2-7, and 2-12 are shown in... Figure 5 middle.

[0236] It should be noted that Examples 2-1 to 2-4 are examples, and Examples 2-5 to 2-12 are comparative examples.

[0237]

[0238] The resin films of Examples 2-1 to 2-4, which use NIR pigment compounds 1 to 3 as shown in Examples 1-1 to 1-3, exhibit excellent spectral characteristics even with low pigment content; that is, they have excellent blue light transmittance and excellent near-infrared light blocking properties.

[0239] <Fabrication of Dielectric Multilayer Films>

[0240] A reflective layer comprising a 42-layer dielectric multilayer film obtained by alternating stacking of TiO2 and SiO2 films was designed. Regarding the reflective layer, simulations were performed using the number of layers in the dielectric multilayer film, the thickness of the TiO2 film, and the thickness of the SiO2 film as parameters. The design was optimized to satisfy the following conditions in the spectral transmittance curves under incident angles of 0 degrees and 30 degrees.

[0241] (iv-1) The wavelength at which the transmittance is 50% is in the range of 600 nm to 850 nm.

[0242] (iv-2) The wavelength at which the transmittance is 50% is in the wavelength range of 385nm to 425nm;

[0243] (iv-3) The average transmittance of light in the wavelength range of 435nm to 650nm is over 88%;

[0244] (iv-4) The average transmittance of light in the wavelength range of 750nm to 1000nm is less than 10%.

[0245] The spectral characteristics of the obtained reflective layer are shown in the table below.

[0246] Table 4

[0247] 0 degrees 30 degrees Spectral characteristics (iv-1) (nm) 714 686 Spectral characteristics (iv-2) (nm) 408 396 Spectral characteristics (iv-3) (%) 95.2 94.5 Spectral characteristics (iv-4) (%) 0.6 0.3

[0248] <Spectral characteristics of filters>

[0249] <Example 3-1>

[0250] By multiplying the internal transmittance of the resin film obtained in Example 2-1 at each wavelength within the wavelength range of 350 nm to 1200 nm with the transmittance of the reflective layer containing the above-mentioned dielectric multilayer film, the spectral characteristics of a filter having a resin film formed on one main surface of a glass substrate and a reflective layer formed on another main surface were estimated.

[0251] <Example 3-2>

[0252] Except that the resin film was changed to the resin film obtained in Examples 2-7, the spectral characteristics of the filter were estimated in the same manner as in Example 3-1.

[0253] <Example 3-3>

[0254] Except that the resin film was changed to the resin film obtained in Example 2-12, the spectral characteristics of the filter were estimated in the same manner as in Example 3-1.

[0255] The spectral characteristics are shown in the table below.

[0256] It should be noted that Example 3-1 is an example, while Examples 3-2 and 3-3 are comparative examples.

[0257] Table 5

[0258] Example 3-1 Example 3-2 Example 3-3 resin film Example 2-1 Example 2-7 Example 2-12 <![CDATA[(iii-1)T 730 -800(60°)(MAX)]]> 1.0 1.1 2.2 <![CDATA[(iii-2)T 435 -480(0°)(AVE)]]> 90.3 89.2 91.7 <![CDATA[(iii-3)T 435 -480(30°)(AVE)]]> 89.5 88.3 90.8

[0259] The filter of Example 3-1 has high visible light transmittance and suppresses the reduction of near-infrared light blocking at high incident angles by using a resin film containing compound 1, which has high transmittance of blue and green light in the spectrum of the resin and exhibits a wide range of absorption characteristics of near-infrared light.

[0260] The filter in Example 3-2 resulted in low visible light transmittance.

[0261] The filter in Example 3-3 does not contain NIR pigments that exhibit a wide range of absorption characteristics in the near-infrared region, resulting in light leakage at high incident angles and reduced near-infrared light blocking.

[0262] <Lightfastness Test>

[0263] <Example 4-1~Example 4-2>

[0264] Glass substrates with resin films were fabricated using the compounds shown in the table below, in the same manner as in Example 1-1 (spectral characteristics of pigment (A) in resin) above.

[0265] A reflective layer of a dielectric multilayer film containing 42 layers was formed by alternately stacking TiO2 and SiO2 layers on the surface of the resin film that does not contact the glass plate, thereby creating a lightfastness test sample.

[0266] In the lightfastness test, the sample was irradiated with light from the surface of the medium multilayer film using a super xenon weathering machine SX75 (manufactured by Suga Testing Machine Co., Ltd.).

[0267] Wavelength: 300nm~400nm

[0268] Temperature: 40℃

[0269] Humidity: 50% RT

[0270] Cumulative light intensity: 6.0 kW·h / m 2

[0271] Measure the spectral transmittance curves before and after irradiation, and calculate the pigment residue rate according to the following formula.

[0272] Pigment residue rate [%) = [Absorbance at the maximum absorption wavelength after irradiation / Absorbance at the maximum absorption wavelength before irradiation] × 100

[0273] The criterion is that if the pigment residue rate is above 70%, it is evaluated as having excellent lightfastness.

[0274] The results are shown in the table below.

[0275] It should be noted that Example 4-1 is an example, and Example 4-2 is a comparative example.

[0276] Table 6

[0277] NIR Pigment (A) Pigment Residue Rate Example 4-1 Compound 1 82％ Example 4-2 Compound 5 52％

[0278] The results above show that when using compound 1, which exhibits excellent spectral properties in the resin, the lightfastness is also excellent.

[0279] The present invention has been described in detail with reference to specific embodiments; however, various changes or modifications may be made without departing from the spirit and scope of the invention, as will be apparent to those skilled in the art. This application is based on Japanese Patent Application No. 2020-128622, filed on July 29, 2020, the contents of which are incorporated herein by reference.

[0280] Industrial practicality

[0281] The filter of the present invention maintains good near-infrared light blocking and visible light transmittance, especially blue light transmittance, while exhibiting excellent near-infrared light blocking characteristics, particularly suppressing the decrease in near-infrared light blocking at high incident angles. It is useful in applications where high-performance information acquisition devices such as conveyor cameras and sensors are increasingly being developed.

[0282] Label Explanation

[0283] 1A, 1B, 1C, 1D... Filters, 10... Substrate, 11... Support, 12... Resin film, 30... Dielectric multilayer film

Claims

1. An optical filter having a substrate and a dielectric multilayer film laminated on at least one principal surface side of the substrate and as an outermost layer, wherein the substrate comprises a resin film comprising a resin and a pigment (A) having a maximum absorption wavelength in the range of 730 nm to 800 nm in dichloromethane, and for the pigment (A), in a spectral transmittance curve of a coated film obtained by dissolving the pigment (A) in the resin in such a manner that the transmittance at the maximum absorption wavelength is 10% and coating on an alkali glass plate, all of the following spectral properties (i-1) to (i-3) are satisfied: (i-1) the absolute value of the difference between the longest wavelength at which the internal transmittance is 50% and the second longest wavelength in the range of wavelengths of 400 nm or more is 100 nm or less, (i-2) the absolute value of the difference between the longest wavelength at which the internal transmittance is 50% and the second longest wavelength in the range of wavelengths of 600 nm or more is 125 nm or more, and (i-3) the absolute value of the difference between the longest wavelength at which the internal transmittance is 50% and the second longest wavelength in the range of wavelengths of 700 nm or more is 150 nm or more, the pigment (A) is a compound represented by the following formula (A), wherein the symbols in formula (A) are as described below, formula (A) optionally has Z, and Z is a five-membered ring or a six-membered ring, the resin film further comprises a pigment (B) having a maximum absorption wavelength in the range of 650 nm to 730 nm in dichloromethane, and the resin film satisfies all of the following spectral properties (ii-1) to (ii-4): (ii-1) when the content of the pigment (A) in the resin film is set to [A] (mass%) and the content of the pigment (B) is set to [B] (mass%), [A] / [B] < 0.85, (ii-2) the absolute value of the difference between the longest wavelength at which the internal transmittance is 50% and the second longest wavelength in the range of wavelengths of 400 nm or more is 100 nm or less, (ii-3) the absolute value of the difference between the longest wavelength at which the internal transmittance is 50% and the second longest wavelength in the range of wavelengths of 600 nm or more is 125 nm or more, and (ii-4) the absolute value of the difference between the longest wavelength at which the internal transmittance is 50% and the second longest wavelength in the range of wavelengths of 700 nm or more is 150 nm or more.

2. The optical filter according to claim 1, wherein the substrate comprises a support and the resin film is laminated on at least one principal surface of the support.

3. The optical filter according to claim 2, wherein the support is glass or absorbing glass. (i-1) the average internal transmission T in the range of wavelengths 430 nm to 460 nm in the spectral transmission curve 430-460(AVE) is 95% or more; (i-2) the average internal transmission T in the range of wavelengths 460 nm to 530 nm in the spectral transmission curve 460-530(AVE) is 97% or more; 4. The optical filter according to any one of claims 1 to 3, wherein the resin comprises a polyimide resin.

5. The optical filter according to any one of claims 1 to 4, wherein the optical filter satisfies all of the following spectral properties (iii-1) to (iii-3): (iii-1) the absolute value of the difference between the longest wavelength at which the internal transmittance is 50% and the second longest wavelength in the range of wavelengths of 400 nm or more is 100 nm or less, (iii-2) the absolute value of the difference between the longest wavelength at which the internal transmittance is 50% and the second longest wavelength in the range of wavelengths of 600 nm or more is 125 nm or more, and (iii-3) the absolute value of the difference between the longest wavelength at which the internal transmittance is 50% and the second longest wavelength in the range of wavelengths of 700 nm or more is 150 nm or more. ​ R 1 ~R 7 Each of the following groups can be independently composed of a hydrogen atom, a halogen atom, a sulfonyl group, a hydroxyl group, a cyano group, a nitro group, a carboxyl group, a phosphate group, an alkyl group having 1 to 10 carbon atoms that can have substituents, an alkoxy group having 1 to 10 carbon atoms that can have substituents, or an acyloxy group having 1 to 10 carbon atoms that can have substituents. 2 ~R 5 R 6 ~R 7 Two adjacent groups in a ring can connect with each other to form a five-membered to an eight-membered ring. ​ X - represents PF6 - , [Rf-SO2] - , [N(Rf-SO2)2] - or BF4 - , Rf represents an alkyl group substituted with at least one fluorine atom, R 8 is a hydrogen atom, a halogen atom or -Y 5 -R 10 , Y 5 is a single bond, an ether bond (-0-), a sulfonyl bond (-S02-), an ester bond (-C(=0)-0- or -0-C(=0)-) or a ureido bond (-NH-C(=0)-NH-), R 10 represents an alkyl group having 1 to 20 carbon atoms which can have a substituent or an aryl group having 6 to 30 carbon atoms which can have a substituent.

2. The filter of claim 1, wherein, ​ ​ ​ ​ (ii-2) internal transmittance T at a wavelength of 700 nm 700 is 5% or less; (ii-3) the average internal transmission T in the range of wavelengths from 730 nm to 800 nm in the spectral transmission curve 730-800(AVE) is 25% or less; (ii-4) the average internal transmittance T in the range of wavelengths 430 nm to 460 nm in the spectral transmittance curve 430-460(AVE) is 92% or more.

3. The filter of claim 2, wherein, The colorant (B) is a squarylium salt colorant. Squarylium salt colorant.

4. The filter of claim 1, wherein, ​ 5. The filter of claim 4, wherein, ​ 6. The filter of claim 1, wherein, ​ 7. The filter of claim 1, wherein, ​ (iii-1) the maximum transmittance T in the range of wavelengths from 730 nm to 800 nm in the spectral transmittance curve for an angle of incidence of 60 degrees 730-800(60°)(MAX) is 1.5% or less; (iii-2) average transmittance T in the range of wavelengths from 435 nm to 480 nm in the spectral transmittance curve for an angle of incidence of 0 degrees 435-480(0°)(AVE) is 85% or more; (iii-3) average transmittance T in the range of wavelengths from 435 nm to 480 nm in the spectral transmittance curve for an angle of incidence of 30 degrees 435-480(30°)(AVE) is 85% or more.

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