Optical filter

Abstract

The present invention relates to an optical filter having a substrate and a dielectric multilayer film that is laminated on at least one main surface side of the substrate and that is an outermost layer, in which the substrate contains a resin film that contains a resin and a dye (A) that has a maximum absorption wavelength in the range of 730-800 nm in dichloromethane, and the dye (A) has a maximum absorption wavelength in the range of 730-800 nm in dichloromethane. And the pigment (A) satisfies specific spectral characteristics in the resin.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 202180059114.1, filed on July 21, 2021. TECHNICAL FIELD

[0002] The present application relates to an optical filter that transmits light in the visible wavelength range and blocks light in the near-infrared wavelength range. BACKGROUND

[0003] In an imaging device using a solid-state imaging element, in order to reproduce a clear image with good color tone, an optical filter that transmits light in the visible light region (hereinafter also referred to as "visible light") and blocks light in the near-infrared wavelength range (hereinafter also referred to as "near-infrared light") is used.

[0004] For such an optical filter, for example, various methods such as a reflection type optical filter that alternately stacks thin films of media having different refractive indexes (a media multilayer film) on one or both surfaces of a transparent substrate and reflects light to be blocked by interference of light can be cited. For an optical filter having a media multilayer film, since the optical film thickness of the media multilayer film changes depending on the incident angle of light, there are problems such as a change in the spectral transmittance curve caused by the incident angle, a leak of light in which the transmittance of near-infrared light that should be obtained with high reflectance increases at a high incident angle, and noise caused by near-infrared light reflected by the media multilayer film. When such an optical filter is used, the spectral sensitivity of the solid-state imaging element can be affected by the incident angle. Therefore, there is a demand for an optical filter that blocks near-infrared light without substantially affecting the visible light transmittance and without incident angle dependence.

[0005] Here, in Patent Documents 1 to 3, an optical filter provided with a layer containing a near-infrared absorbing pigment in order to reduce the incident angle dependence is described.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT DOCUMENTS

[0008] Patent Document 1: International Publication No. 2019 / 022069

[0009] Patent Document 2: International Publication No. 2019 / 168090

[0010] Patent Document 3: Japanese Patent Application Publication No. 2019-164269 SUMMARY

[0011] PROBLEMS TO BE SOLVED BY THE INVENTION

[0012] However, in the optical filter described in Patent Document 1, there is room for improvement in terms of near-infrared light blocking properties. In the optical filters described in Patent Documents 2 and 3, there is room for improvement in terms of transmittance in the visible light region.

[0013] Accordingly, an object of the present application is to provide an optical filter which, while maintaining high visible light transmittance, suppresses a decrease in near-infrared light blocking at high angles of incidence and the like.

[0014] Means for solving the problem

[0015] The present application provides an optical filter having the following configuration.

[0016] [1] An optical filter having a substrate and a dielectric multilayer film stacked on at least one main surface side of the substrate and serving as an outermost layer, wherein the substrate includes a resin film including 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 coating 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) Average internal transmittance T in the range of wavelengths of 430 nm to 460 nm in the spectral transmittance curve 430-460(AVE) is 95% or more; (i-2) Average internal transmittance T in the range of wavelengths of 460 nm to 530 nm in the spectral transmittance curve 460-530(AVE) is 97% or more; (i-3) The absolute value of the difference between the shortest wavelength at which the internal transmittance is 50% and the second shortest wavelength in the range of wavelengths of 600 nm or more is 125 nm or more.

[0017] Effects of the Invention

[0018] According to the present application, it is possible to provide an optical filter having high visible light transmittance and suppressing a decrease in near-infrared light blocking at high angles of incidence. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a cross-sectional view schematically showing one example of an optical filter of one embodiment.

[0020] Figure 2 is a cross-sectional view schematically showing another example of an optical filter of one embodiment.

[0021] Figure 3 is a cross-sectional view schematically showing another example of an optical filter of one embodiment.

[0022] Figure 4 A cross-sectional view showing another example of a filter of one embodiment.

[0023] Figure 5 A graph showing spectral transmittance curves of the resin films of Example 2-1, Example 2-7, and Example 2-12. DETAILED DESCRIPTION

[0024] Hereinafter, an embodiment of the present application will be described.

[0025] In this specification, a near-infrared absorbing dye is sometimes referred to simply as an "NIR dye", and an ultraviolet absorbing dye is sometimes referred to simply as a "UV dye".

[0026] In this specification, a compound represented by formula (I) is referred to as compound (I). The same applies to a compound represented by another formula. A dye including compound (I) is also referred to as dye (I), and the same applies to another dye. In addition, a group represented by formula (I) is also referred to as group (I), and the same applies to a group represented by another formula.

[0027] In this specification, internal transmittance refers to transmittance obtained by subtracting the effect of interface reflection from measured transmittance, which is represented by the formula of {measured transmittance / (100-reflectance)} x 100.

[0028] In this specification, in the case of a transmittance of a substrate, a transmittance of a resin film in the case where a dye is contained in a resin, and the like, which is described as "transmittance", all of them are "internal transmittance". On the other hand, a transmittance measured with a dye dissolved in a solvent such as dichloromethane, and a transmittance of a filter having a dielectric multilayer film are measured transmittances.

[0029] In this specification, for a specific wavelength range, a transmittance of, for example, 90% or more means that the transmittance is not less than 90% in the entire wavelength range, i.e., the minimum transmittance in the wavelength range is 90% or more. Similarly, for a specific wavelength range, a transmittance of, for example, 1% or less means that the transmittance is not more than 1% in the entire wavelength range, i.e., the maximum transmittance in the wavelength range is 1% or less. The same applies to internal transmittance. The average transmittance and the average internal transmittance in a specific wavelength range are the arithmetic average of the transmittance and the internal transmittance per 1 nm in the wavelength range.

[0030] In this specification, "~" indicating a numerical range includes the upper limit and the lower limit.

[0031] <Filter>

[0032] A filter of one embodiment of the present application (hereinafter also referred to as "the present filter") has a substrate and a dielectric multilayer film stacked on at least one of main surface sides of the substrate and serving as an outermost layer.

[0033] A configuration example of the present filter will be described using the drawings. Figures 1-4 A cross-sectional view of an example of a filter of one embodiment is schematically shown.

[0034] Figure 1 The filter 1A illustrated is an example in which the dielectric multilayer film 30 is provided on one main surface side of the substrate 10. Note that "a specific layer is provided on the main surface side of the substrate" is not limited to a case where the layer is provided in contact with the main surface of the substrate, and includes a case where another functional layer is provided between the substrate and the layer.

[0035] Figure 2 The filter 1B illustrated is an example in which the dielectric multilayer film 30 is provided on both main surface sides of the substrate 10.

[0036] Figure 3 The filter 1C illustrated is an example in which the substrate 10 includes the support 11 and the resin film 12 stacked on one main surface side of the support 11. The filter 1C further includes the dielectric multilayer film 30 on each of the resin film 12 and the main surface side of the support 11 on which the resin film 12 is not stacked.

[0037] Figure 4 The filter 1D illustrated is an example in which the substrate 10 includes the support 11 and the resin film 12 stacked on both main surface sides of the support 11. The filter 1D further includes the dielectric multilayer film 30 on each of the resin films 12.

[0038] <Substrate>

[0039] In the filter of one embodiment of the present application, the substrate includes a resin film including a resin and a pigment (A) having a maximum absorption wavelength in the range of 730 nm to 800 nm in dichloromethane. The pigment (A) is a near-infrared absorbing (NIR) pigment. With the substrate including the resin film including the near-infrared absorbing pigment, the decrease in the spectral characteristics of the dielectric multilayer film at a high incident angle, e.g., the occurrence of light leakage, noise, or the like in the near-infrared region, can be suppressed by the absorption characteristics of the substrate.

[0040] <Pigment (A)>

[0041] The pigment (A) satisfies specific spectral characteristics in the resin used for the substrate. Specifically, in a spectral transmittance curve of a coating 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 the coating film on an alkali glass plate, all of the following spectral characteristics (i-1) to (i-3) are satisfied.

[0042] (i-1) The average internal transmittance T in the range of wavelengths of 430 nm to 460 nm in the spectral transmittance curve430-460(AVE) 95% or more; (i-2) Average internal transmittance T in the range of wavelengths from 460 nm to 530 nm in the spectral transmittance curve 460-530(AVE) 97% or more; (i-3) The absolute value of the difference between the shortest wavelength at which the internal transmittance is 50% and the second shortest wavelength in the range of wavelengths of 600 nm or more is 125 nm or more.

[0043] The filter of the present application containing the dye (A) satisfying all the above spectral characteristics is a filter having high visible light transmittance and suppressing the decrease in near-infrared light blocking at high incident angles by absorbing near-infrared light in a wide range.

[0044] By satisfying the spectral characteristic (i-1), a filter having excellent transmittance of visible light, particularly blue light, can be obtained.

[0045] The spectral characteristic (i-1) is preferably 96% or more.

[0046] By satisfying the spectral characteristic (i-2), a filter having excellent transmittance of visible light, particularly green light, can be obtained.

[0047] The spectral characteristic (i-2) is preferably 98% or more.

[0048] By satisfying the spectral characteristic (i-3), a filter absorbing near-infrared light in a wide wavelength range can be obtained. Thus, in a wavelength band in which the dielectric multilayer film cannot completely block light at high incident angles and light leakage easily occurs, light leakage can be effectively prevented. In order to absorb light in a wide wavelength range, a plurality of dyes having different maximum absorption wavelengths can be considered to be combined, but when a plurality of NIR dyes are combined, although light in the near-infrared region can be blocked in a wide range, on the other hand, there is a tendency that the transmittance in the visible region also decreases. By the dye (A) itself exhibiting a wide range of absorption characteristics in the resin, even without combining a plurality of NIR dyes, light in the near-infrared region can be effectively blocked using only the dye (A) while maintaining the transmittance in the visible region.

[0049] The absolute value in the spectral characteristic (i-3) is preferably 128 nm or more, and more preferably 130 nm or more.

[0050] As the dye (A), a cyanine dye, a squarylium dye, a phthalocyanine dye, an ammonium dye, and a diimmonium dye can be exemplified, and from the viewpoint of easily satisfying the above spectral characteristics (i-1) to (i-3), a cyanine dye is preferred.

[0051] As the cyanine dye, a compound represented by the following formula (A) is particularly preferred. ​

[0052]

[0053] In formula (A), the symbols are as described below.

[0054] R 1 ~R 7 each independently is a hydrogen atom, a halogen atom, a sulfo group, a hydroxyl group, a cyano group, a nitro group, a carboxyl group, a phosphoric acid group, an alkyl group having 1 to 10 carbon atoms which can have a substituent, an alkoxy group having 1 to 10 carbon atoms which can have a substituent, or an acyloxy group having 1 to 10 carbon atoms which can have a substituent.

[0055] In formula (A), R 1 ~R 7 The symbols on the left and right of the formula can be the same or different, but are preferably all the same.

[0056] As the substituent in the alkyl group having 1 to 10 carbon atoms which can have a substituent, the alkoxy group having 1 to 10 carbon atoms which can have a substituent, or the acyloxy group having 1 to 10 carbon atoms which can have a substituent, a halogen atom or an alkoxy group having 1 to 10 carbon atoms can be exemplified.

[0057] Here, in the present specification, unless otherwise specified, the alkyl group can be linear, branched, cyclic, or a structure obtained by combining these structures. The same is true for the alkyl group possessed by the alkoxy group. As the halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like can be exemplified, and a fluorine atom and a chlorine atom are preferred.

[0058] From the viewpoint of ease of synthesis and the like, R 1 Each independently 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 particularly preferably a hydrogen atom.

[0059] R 2 ~R 7 Each independently is preferably a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms which can have a substituent, an alkoxy group having 1 to 10 carbon atoms which can have a substituent, or an acyloxy group having 1 to 10 carbon atoms which can have a substituent. From the viewpoint of ease of synthesis and the like, R 2 ~R 7 Each independently 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 which can have a substituent.

[0060] From the viewpoint of solubility in a transparent resin or a solvent, R 6 ~R 7at least one of R1to R4in the formula (A) is preferably an alkyl group having 1 to 10 carbon atoms, more preferably a secondary or tertiary branched alkyl group having 10 or less carbon atoms, further preferably a tertiary butyl group, an isopropyl group, or an isobutyl group.

[0061] R 2 ~R 5 , R 6 ~R 7 The adjacent two groups in the formula (A) can be linked to each other to form a five- to eight-membered ring. The ring can be aliphatic or aromatic.

[0062] The formula (A) optionally has Z. Z is a five- or six-membered ring. In the case where the formula (A) has Z, it is preferable from the viewpoint of durability. Note that the hydrogen atom bonded to the carbon atom constituting Z can be substituted with an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms.

[0063] In the present specification, unless otherwise specified, an aryl group refers to a group bonded via a carbon atom constituting an aromatic ring possessed by an aromatic compound, such as a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a thiophene ring, a pyrrole ring, or the like.

[0064] X - represents a monovalent anion.

[0065] X - is preferably PF6 - , [Rf-SO2] - , [N(Rf-SO2)2] - , or BF4 - . Rf represents an alkyl group substituted with at least one fluorine atom, preferably a perfluoroalkyl group having 1 to 8 carbon atoms, particularly preferably a -CF3 group.

[0066] By the anion being such a structure, a pigment compound (A) having excellent light resistance can be obtained.

[0067] R 8 represents a hydrogen atom, a halogen atom, or -Y 5 -R 10 (Y 5 is a single bond, an ether bond (-O-), a sulfonyl bond (-SO2-), an ester bond (-C(=O)-O- or -O-C(=O)-), or a urea bond (-NH-C(=O)-NH-), and R 10 is 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).

[0068] R 8 is preferably a hydrogen atom, a halogen atom, -Y 5 -Y 5 -R 10More preferably, hydrogen atom, chlorine atom, alkyl group having 1 to 10 carbon atoms, aryl group having 6 to 10 carbon atoms which can be substituted with halogen atom.

[0069] In formula (A), more specifically, compounds in which the atoms or groups bonded to each skeleton are shown in the following table, respectively, can be exemplified. In all of the compounds shown in the following table, R 1 ~R 7 All of the left and right of formula are the same.

[0070] Table 1

[0071] The pigment (A) can be synthesized, for example, as shown in the synthesis flow chart of the pigment (Al) in which R 1 ~R 5 , R 7 is hydrogen atom and X - is BF4 - .

[0072]

[0073] (1) A salicylaldehyde (a) and an alkyne compound (b) having an R 6 group are reacted to obtain a compound (c).

[0074] (2) The compound (c) is reacted with 4-dimethylaminopyridine to obtain a compound (d).

[0075] (3) The compound (d) is reacted with methylmagnesium bromide and tetrafluoroboric acid to obtain a compound (e).

[0076] (4) The compound (e) is reacted with an aldehyde condensation diphenylamine hydrochloride (f) having an R 8 group to obtain the pigment (Al).

[0077] In the case where X - is PF6 - , the synthesis can be performed by using hexafluorophosphoric acid instead of tetrafluoroboric acid in the above step (3), in the case where X - is [Rf-SO2] - , the synthesis can be performed by using Rf-SO3H instead of tetrafluoroboric acid in the above step (3), and in the case where X - is [N(Rf-SO2)2] , the synthesis can be performed by using NH(Rf-SO2)2instead of tetrafluoroboric acid in the above step (3).

[0078] The resin film can contain one pigment (A) alone, or two or more pigments (A) in combination.

[0079] From the viewpoint of the spectral properties and Tg of the resin film and the solubility of the pigment (A) in the resin film, the content of the pigment (A) in the resin film is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, relative to 100 parts by mass of the resin.

[0080] < Pigment (B) >

[0081] In the present filter, the resin film preferably further contains a pigment (B) having a maximum absorption wavelength in the range of 650 to 730 nm in dichloromethane. The pigment (B) is also a near-infrared absorbing (NIR) pigment like the pigment (A). Thereby, near-infrared light can be more effectively blocked.

[0082] In the case where the resin film contains the pigment (A) and the pigment (B), the resin film preferably satisfies all of the following spectral properties (ii-1) to (ii-4).

[0083] (ii-1) When the content of the pigment (A) in the resin film is set as [A] (mass %) and the content of the pigment (B) is set as [B] (mass %), [A] / [B]<0.85; (ii-2) The internal transmittance T at a wavelength of 700 nm 700 is 5% or less; (ii-3) The average internal transmittance T in the range of 730 to 800 nm in the spectral transmittance curve 730-800(AVE) is 25% or less; (ii-4) The average internal transmittance T in the range of 430 to 460 nm in the spectral transmittance curve 430-460(AVE) is 92% or more.

[0084] By satisfying the spectral property (ii-1), it means that the pigment (A) can absorb near-infrared light in a wide range, and therefore even if the content of the pigment (A) is small, light around the maximum absorption wavelength of the pigment (A) can be sufficiently blocked.

[0085] The spectral property (ii-1) is more preferably [A] / [B]<0.75, and further preferably 0.05<[A] / [B].

[0086] By satisfying the spectral property (ii-2), it means that the blocking property of near-infrared light is high.

[0087] The spectral property (ii-2) is more preferably 4% or less.

[0088] By satisfying the spectral property (ii-3), it means that the blocking property of near-infrared light is high.

[0089] The spectral property (ii-3) is more preferably 24% or less.

[0090] By satisfying the spectral property (ii-4), it means that the transmittance of blue light is high.

[0091] The spectral property (ii-4) is more preferably 92.5% or more.

[0092] As the pigment (B), at least one selected from the group consisting of squarylium salt pigments, cyanine pigments, phthalocyanine pigments, ammonium pigments, and diimmonium pigments, and particularly preferably squarylium salt pigments.

[0093] As the squarylium salt pigment, a compound represented by the following formula (I) is preferable.

[0094]

[0095] In formula (I), the symbols are as described below.

[0096] R 24 and R 26 each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, -NR 27 R 28 (R 27 and R 28 each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, -C(=O)-R 29 (R 29 a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which can have a substituent, or an aryl group having 6 to 11 carbon atoms which can have a substituent, or an aralkyl group having 7 to 18 carbon atoms which can have a substituent and can have an oxygen atom between carbon atoms, -NHR 30 or -SO2-R 30 (R 30 each is an alkyl group having 1 to 25 carbon atoms in which one or more hydrogen atoms can be substituted with a halogen atom, a hydroxyl group, a carboxyl group, a sulfo group, or a cyano group and can have an unsaturated bond, an oxygen atom, a saturated or unsaturated ring structure between carbon atoms, or a group represented by the following formula (S) (R 41 , R 42 independently represent 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).

[0097]

[0098] R 21 and R22 , R 22 and R 25 and R 21 and R 23 may be linked to each other and form, together with the nitrogen atom, a 5- or 6-membered heterocycle A, B and C, respectively.

[0099] For R 21 and R 22 in the case of forming heterocycle A, as the divalent group -Q- to which R 21 and R 22 are bonded, an alkylene group in which a hydrogen atom can be substituted with an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms or an acyloxy group having 1 to 10 carbon atoms which can have a substituent, or an alkyleneoxy group in which a hydrogen atom can be substituted with an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms or an acyloxy group having 1 to 10 carbon atoms which can have a substituent.

[0100] For R 22 and R 25 in the case of forming heterocycle B, and R 21 and R 23 in the case of forming heterocycle C, as the divalent group -X 22 and R 25 are bonded, a divalent group -X 1 -Y 1 - and a divalent group -X 21 -Y 23 are bonded, X 2 and X 2 are bonded (the side bonded to nitrogen is X 1 and X 2 ), X 1 and X 2 are each a group represented by the following formula (1x) or (2x), and Y 1 and Y 2 are each a group represented by any one selected from the group consisting of the following formulas (1y) to (5y). In the case where X 1 and X 2 are each a group represented by the following formula (2x), Y 1 and Y 2 may each be a single bond, in which case an oxygen atom can be present between the carbon atoms.

[0101]

[0102] In formula (1x), 4 Z's each independently represent 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 (R38 and R 39 each independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms). R 31 ~R 36 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms, R 37 represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms.

[0103] R 27 , R 28 , R 29 , R 31 ~R 37 , R 21 ~R 23 and R 25 each can be bonded to the other any one of them to form a 5-membered ring or a 6-membered ring. R 31 and R 36 may be directly bonded, R 31 and R 37 may be directly bonded.

[0104] R 21 and R 22 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms which can have a substituent or an allyl group which can have a substituent, or an aryl group having 6 to 11 carbon atoms which can have a substituent or an aralkyl group having 6 to 11 carbon atoms which can have a substituent. R 23 and R 25 each independently represents 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.

[0105] The compound (I) can be produced, for example, by the publicly known method described in the specification of U.S. Patent No. 5543086, the specification of U.S. Patent Application Publication No. 2014 / 0061505, and International Publication No. 2014 / 088063.

[0106] The resin film can contain one colorant (B) alone, or two or more colorants (B) in combination.

[0107] The content of the colorant (B) in the resin film is preferably 0.1 to 15 parts by mass, and more preferably 0.5 to 10 parts by mass, with respect to 100 parts by mass of the resin.

[0108] <Other colorants>

[0109] The resin film can contain other colorants, such as a UV colorant, in addition to the NIR colorant.

[0110] As the UV pigment, the following can be exemplified: oxazoles, merocyanines, cyanines, naphthalimides, oxadiazoles, oxazines, oxazolidines, naphthalic acids, styryls, anthracenes, cyclic carbonyls, triazoles, and the like can be exemplified. In addition, the UV pigment can be used singly or in combination of two or more kinds.

[0111] <Substrate Constitution>

[0112] The substrate in the present filter can be a single layer structure or a multi-layer structure. In addition, as the material of the substrate, as long as it is a transparent material that transmits visible light of 400 nm to 700 nm, it can be an organic material or an inorganic material, and is not particularly limited.

[0113] In the case where the substrate is a single layer structure, a resin substrate composed of a resin film containing a resin and a NIR pigment (A) is preferable.

[0114] In the case where the substrate is a multi-layer structure, a composite substrate in which a resin film containing a NIR pigment (A) is laminated on at least one main surface of a support is preferable. At this time, the support preferably contains a transparent resin or a transparent inorganic material.

[0115] As the resin, there is no limitation as long as it is a transparent resin, and one or more kinds of transparent resins selected from the group consisting of polyester resins, acrylic resins, epoxy resins, ene-thiol resins, polycarbonate resins, polyether resins, polyarylate resins, polysulfone resins, polyethersulfone resins, polyphenylene resins, polyarylene ether phosphine oxide resins, polyamide resins, polyimide resins, polyamide-imide resins, polyolefin resins, cyclic olefin resins, polyurethane resins, and polystyrene resins, and the like can be used. These resins can be used singly or in combination of two or more kinds.

[0116] From the viewpoint of the spectral properties, the glass transition temperature (Tg), and the adhesion of the resin film, one or more kinds of resins selected from the group consisting of polyimide resins, polycarbonate resins, polyester resins, and acrylic resins are preferable.

[0117] In the case where the substrate contains a NIR pigment (B), other pigments, these pigments can be contained in the resin film containing a NIR pigment (A), and in addition, can be contained in other resin films.

[0118] As the transparent inorganic material, glass or a crystalline material is preferable.

[0119] As the glass that can be used for the support body, an absorption type glass (near-infrared absorbing glass) containing a copper ion in a fluorophosphate glass or a phosphate glass or the like, a soda-lime glass, a borosilicate glass, an alkali-free glass, a quartz glass, or the like can be exemplified. As the glass, an absorption type glass is preferable depending on the purpose, and a phosphate glass, a fluorophosphate glass is preferable from the viewpoint of absorbing infrared light. When a large amount of red light (600 nm to 700 nm) is intended to be absorbed, an alkali glass, an alkali-free glass, a quartz glass is preferable. Note that the "phosphate glass" also includes a silicon phosphate glass in which a part of the glass framework is composed of SiO2.

[0120] As the glass, a chemically strengthened glass obtained by replacing alkali metal ions (for example, Li ions, Na ions) having a small ionic radius present on the main surface of a glass sheet with alkali metal ions (for example, Na ions or K ions for Li ions, K ions for Na ions) having a larger ionic radius by ion exchange at a temperature below the glass transition temperature can be used.

[0121] As the crystal material that can be used for the support body, a birefringent crystal such as a quartz, a lithium niobate, a sapphire, or the like can be exemplified.

[0122] As the support body, from the viewpoint of shape stability related to long-term reliability of spectral characteristics, mechanical characteristics, and the like, handleability at the time of filter production, and the like, an inorganic material is preferable, and a glass, a sapphire is particularly preferable.

[0123] The resin film can be formed by dissolving or dispersing the pigment (A), a resin or a raw material component of the resin, and each component as needed in a solvent to prepare a coating liquid, coating the coating liquid on a support body and drying it, and further curing it as needed. The above support body can be the support body contained in the present filter, or a peelable support body used only at the time of forming the resin film. In addition, the solvent can be a dispersion medium capable of stable dispersion or a solvent capable of dissolution.

[0124] In addition, in order to improve voids caused by minute bubbles, depressions caused by attachment of foreign matter or the like, shrinkage holes in the drying process, or the like, the coating liquid can contain a surfactant. Furthermore, at the time of coating the coating liquid, for example, a dip coating method, a flow coating method, a spin coating method, or the like can be used. The above coating liquid is coated on a support body, and then dried, whereby a resin film is formed. In addition, in the case where the coating liquid contains a raw material component of a transparent resin, further curing treatment such as heat curing, light curing, or the like is performed.

[0125] In addition, the resin film can also be made into a film shape by extrusion molding. In the case where the substrate is a single layer structure (resin substrate) composed of the resin film containing the pigment (A), the resin film can be directly used as the substrate. In the case where the substrate is a multi-layer structure (composite substrate) having a support and the resin film containing the pigment (A) laminated on at least one main surface of the support, the substrate can be manufactured by laminating the film on the support and integrating it by heat pressure bonding or the like.

[0126] The resin film can have one layer or two or more layers in the optical filter. In the case where the resin film has two or more layers, the layers can have the same constitution or different constitutions.

[0127] The thickness of the resin film is preferably 0.3 μm to 20 μm. The optical filter of the present application can effectively block near-infrared light in a wide range by containing the NIR pigment (A) satisfying the specific spectral characteristics in the resin even if the content of the pigment is small. Therefore, the resin film containing the pigment (A) can be made thin. Note that in the case where the resin film has multiple layers, the total thickness of the layers is preferably 0.6 μm to 40 μm.

[0128] In addition, in the case where the substrate is a single layer structure (resin substrate) composed of the resin film containing the pigment (A), the thickness of the resin film is preferably 50 μm to 150 μm.

[0129] In the case where the substrate is a multi-layer structure (composite substrate) having a support and the resin film containing the 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.

[0130] The shape of the substrate is not particularly limited and can be block-shaped, plate-shaped, or film-shaped.

[0131] In addition, from the viewpoint of reducing warping when forming the dielectric multilayer film and reducing the height of the optical element, the thickness of the substrate is preferably 300 μm or less, in the case where the substrate is a resin substrate composed of the resin film, the thickness of the substrate is preferably 50 μm to 300 μm, and in the case where 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.

[0132] <Dielectric Multilayer Film>

[0133] In the present optical filter, the dielectric multilayer film is laminated on at least one main surface side of the substrate and serves as the outermost layer.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] (iv-1) The wavelength at which the transmittance is 50% is in the wavelength range of 600nm to 850nm. (iv-2) The wavelength at which the transmittance is 50% is in the wavelength range of 385nm to 425nm; (iv-3) The average transmittance of light in the wavelength range of 435nm to 650nm is over 88%; (iv-4) The average transmittance of light in the wavelength range of 750nm to 1000nm is less than 10%.

[0140] Further, the NIR reflecting layer preferably has a steep change in transmittance in the wavelength range at the boundary between the transmissive region and the light blocking region. To this end, the total number of layers of the dielectric multilayer film constituting the reflecting layer is preferably 15 layers or more, more preferably 25 layers or more, and further preferably 30 layers or more. However, when the total number of layers is increased, warping or the like occurs or the film thickness increases, and thus the total number of layers is preferably 100 layers or less, more preferably 75 layers or less, and further preferably 60 layers or less. In addition, the film thickness of the reflecting layer as a whole is preferably 2 μm to 10 μm.

[0141] If the total number of layers of the dielectric multilayer film and the film thickness are within the above ranges, the NIR reflecting layer satisfies the requirements for miniaturization and can suppress the angle of incidence dependence while maintaining high productivity. In the formation of the dielectric multilayer film, for example, a vacuum film formation process such as a CVD method, a sputtering method, a vacuum evaporation method, or a wet film formation process such as a spray method or a dip method can be used.

[0142] The prescribed spectral characteristics can be imparted using one NIR reflecting layer (one set of dielectric multilayer film), or the prescribed spectral characteristics can be imparted using two or more NIR reflecting layers. In the case of having two or more NIR reflecting layers, each reflecting layer can have the same constitution or a different constitution. In the case of having two or more reflecting layers, the reflecting layers are usually constituted by a plurality of reflecting layers that differ in the reflecting wavelength band. In the case of providing two reflecting layers, one layer can be a near-infrared reflecting layer that blocks light in the short wavelength band in the near-infrared region, and the other layer can be a near-infrared / near-ultraviolet reflecting layer that blocks light in both the long wavelength band in the near-infrared region and the near-ultraviolet region.

[0143] As the antireflection layer, a dielectric multilayer film, a medium refractive index medium, a moth-eye structure in which the refractive index gradually changes, or the like can be cited. Among these, from the viewpoint of optical efficiency and productivity, a dielectric multilayer film is preferred. The antireflection layer is obtained by alternately stacking dielectric films, like the reflecting layer.

[0144] <Filter>

[0145] The filter of the present application preferably satisfies all of the following spectral characteristics (iii-1) to (iii-3) by adopting the above constitution.

[0146] (iii-1) The maximum transmittance T in the range of wavelengths from 730 nm to 800 nm in the spectral transmittance curve of light having an incident angle of 60 degrees 730-800(60°)(MAX) is 1.5% or less; (iii-2) The average transmittance T in the range of wavelengths from 435 nm to 480 nm in the spectral transmittance curve of light having an incident angle 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 at an incident angle of 30 degrees 435-480(30°)(AVE) is 85% or more.

[0147] By satisfying the spectral property (iii-1), a filter in which light at a high incident angle does not leak and which has high blocking properties for near-infrared light can be obtained.

[0148] The spectral property (iii-1) is more preferably 1.0% or less.

[0149] By satisfying the spectral property (iii-2), a filter in which the transmittance of blue light is excellent can be obtained.

[0150] The spectral property (iii-2) is more preferably 89% or more.

[0151] By satisfying the spectral property (iii-3), a filter in which the transmittance of blue light is excellent even for light at a high incident angle can be obtained.

[0152] The spectral property (iii-3) is more preferably 89% or more.

[0153] The present filter may, for example, have a constituent element (layer) or the like that imparts absorption produced by inorganic fine particles or the like that control the transmittance and absorption of light in a specific wavelength range as another constituent element. As specific examples of inorganic fine particles, ITO (indium tin oxide), ATO (antimony-doped tin oxide), cesium tungstate, lanthanum boride, or the like can be listed. ITO fine particles and cesium tungstate fine particles have high visible light transmittance and have light absorption properties in a wide range of infrared wavelength ranges of greater than 1200 nm, and thus can be used in cases where blocking of such infrared light is required.

[0154] The present filter can provide an imaging device having excellent color reproducibility, for example, in the case of being used for an imaging device such as a digital camera. An imaging device using the present filter has a solid-state imaging element, an imaging lens, and the present filter. The present filter can be used, for example, in such a manner that it is disposed between the imaging lens and the solid-state imaging element, or is directly attached to the solid-state imaging element, the imaging lens, or the like of the imaging device by means of an adhesive layer.

[0155] Example

[0156] Next, the present application will be described more specifically by means of examples.

[0157] In the measurement of each spectral property, a UV-visible spectrophotometer (manufactured by Hitachi High-Technologies Corporation, UH-4150 type) was used.

[0158] Note that the spectral characteristics in cases where the angle of incidence is not specifically described are values measured under conditions in which the angle of incidence is 0 degrees (with respect to a direction perpendicular to the main surface of the optical filter).

[0159] The pigments used in each example are described below.

[0160] Compound 1, 2, 3: synthesized by the method described later

[0161] Compound 4: synthesized based on Dyes and pigments 73 (2007) 344-352.

[0162] Compound 5: synthesized based on International Publication No. 2019 / 168090.

[0163] Compound 6: manufactured by FEW Chemicals Co., Ltd., product name S2137

[0164] Compound 7: synthesized based on Japanese Patent Application Publication No. 2019-164269

[0165] Compound 8: phthalocyanine manufactured by Yamada Chemical Industry Co., Ltd., product name: FDR-026

[0166] Compound 9: synthesized based on International Publication No. 2017 / 135359

[0167] Compound 10: synthesized based on Japanese Patent No. 6358114.

[0168] Compound 11: synthesized based on U.S. Patent Application Publication No. 2014 / 0061505, International Publication No. 2014 / 088063.

[0169] Compound 12: synthesized based on U.S. Patent No. 5543086.

[0170]

[0171]

[0172]

[0173] <Synthesis of Compound 1>

[0174] <Step 1>

[0175] In a 1 L round-bottom flask, 3,3-dimethyl-1-butyne (13 g, 160 mmol) and tetrahydrofuran (40 mL) were added, cooled to -78°C and stirred, and n-butyllithium (1.6 M in n-hexane, 100 mL) was added dropwise and stirred for 1 hour at -78°C. Then, salicylaldehyde (10 g, 82 mmol) dissolved in tetrahydrofuran (80 mL) was added and stirred for 3 hours at room temperature. After the completion of the reaction, quenching was performed by adding saturated ammonium chloride aqueous solution, and extraction was performed using ethyl acetate. After removing the solvent, manganese dioxide (35 g, 400 mmol), acetone (80 mL) were added, and stirred for 16 hours at room temperature. After the completion of the reaction, filtration was performed, the solvent of the filtrate was removed, and then purification was performed by column chromatography, thereby obtaining 6.1 g (37%) of intermediate (c1).

[0176] <Step 2>

[0177] In a 500 mL round-bottom flask, intermediate (c1) (6.1 g, 30 mmol), N,N-dimethylformamide (120 mL) were added, cooled to 0°C and stirred, and 4-dimethylaminopyridine (0.37 g, 3.0 mmol) was added and reacted for 16 hours at room temperature. After the completion of the reaction, quenching was performed by adding water, extraction was performed using ethyl acetate, the solvent was removed, and then purification was performed by column chromatography, thereby obtaining 4.2 g (70%) of intermediate (d1).

[0178] <Step 3>

[0179] In a 500 mL round-bottom flask, intermediate 2 (4.2 g, 21 mmol) and tetrahydrofuran (50 mL) were added, cooled to 0°C and stirred, and methylmagnesium bromide (1 M in tetrahydrofuran, 30 mL) was added dropwise and reacted for 5 hours at room temperature. After the completion of the reaction, quenching was performed by adding ice water, 42% aqueous solution of tetrafluoroboric acid (150 mL) was added, and stirred for 30 minutes at room temperature. Extraction was performed using dichloromethane, the solvent was removed, and then the precipitated solid was washed with ethyl acetate, thereby obtaining 4.4 g (77%) of intermediate (e1).

[0180] <Step 4>

[0181] In a 500 mL round-bottom flask, intermediate (e1) (4.4 g, 15 mmol), malononitrile salt of diphenylamine hydrochloride (1.9 g, 7.5 mmol), sodium acetate (3.0 g, 36 mmol), acetic acid (60 mL), acetic anhydride (60 mL) were added, and stirred for 2 hours at 80°C. After the completion of the reaction, water was added, the precipitated solid was recovered by filtration, and purification was performed by column chromatography, thereby obtaining 1.9 g (50%) of compound 1.

[0182] <Synthesis of Compound 2>

[0183] <Step 1>

[0184] In a 500 mL eggplant flask, intermediate (d1) (5.0 g, 25 mmol) obtained by the same synthetic method as compound 1 was added, tetrahydrofuran (60 mL) was added, cooled to 0°C and stirred, methyl magnesium bromide (1M in tetrahydrofuran, 37 mL) was added dropwise, and it was allowed to react for 5 hours at room temperature. After the reaction was completed, ice water was added for quenching, 60% aqueous solution of hexafluoro-phosphoric acid (150 mL) was added, and it was stirred for 30 minutes at room temperature. Extraction was performed using dichloromethane, the solvent was removed, and then the precipitated solid was washed with ethyl acetate, thereby obtaining 7.2 g (84%) of intermediate (e2).

[0185] <Step 2>

[0186] In a 500 mL eggplant flask, intermediate (e2) (5.2 g, 15 mmol), malonamide hydrochloride (1.9 g, 7.5 mmol), sodium acetate (3.0 g, 36 mmol), acetic acid (60 mL), acetic anhydride (60 mL) were added, and it was stirred for 2 hours at 80°C. After the reaction was completed, water was added, filtered, and the precipitated solid was recovered, and purified using column chromatography, thereby obtaining 1.8 g (41%) of compound 2.

[0187] <Synthesis of compound 3>

[0188] <Step 1>

[0189] In a 500 mL eggplant flask, intermediate (d1) (3.0 g, 15 mmol) obtained by the same synthetic method as compound 1 was added, tetrahydrofuran (36 mL) was added, cooled to 0°C and stirred, methyl magnesium bromide (1M in tetrahydrofuran, 22 mL) was added dropwise, and it was allowed to react for 5 hours at room temperature. After the reaction was completed, ice water was added for quenching, 10% aqueous solution of bis(trifluoromethylsulfonyl)imide (100 mL) was added, and it was stirred for 30 minutes at room temperature. Extraction was performed using dichloromethane, the solvent was removed, and then the precipitated solid was washed with ethyl acetate, thereby obtaining 5.3 g (75%) of intermediate (e3).

[0190] <Step 2>

[0191] In a 500 mL eggplant flask, intermediate (e3) (5.3 g, 11 mmol), malonate dibenzylideneamine hydrochloride (1.4 g, 5.3 mmol), sodium acetate (2.1 g, 26 mmol), acetic acid (50 mL), acetic anhydride (50 mL) were added and stirred at 80°C for 2 hours. After the completion of the reaction, water was added, filtered and the precipitated solid was recovered and purified using column chromatography to obtain 1.6 g (42%) of compound 3.

[0192] < Spectral properties of the pigment (A) in the resin >

[0193] < Examples 1-1 to 1-10 >

[0194] A polyimide resin (C-3G30G manufactured by Mitsubishi Gas Chemical Corporation) was dissolved in an organic solvent (cyclohexanone: γ-butyrolactone = 1:1 mass ratio) at a concentration of 8.5 mass%.

[0195] The NIR pigment compound shown in the following table was added to the polyimide resin solution prepared above so that the NIR pigment compound was 6 parts by mass with respect to 100 parts by mass of the resin, and was stirred while heating at 50°C for 2 hours. The resin solution containing the pigment was coated on a glass substrate (alkali glass, D263 manufactured by SCHOTT) and dried to obtain a resin film (coated film) having a film thickness of 1 μm.

[0196] The spectral internal transmittance curve was calculated using the spectral transmittance curve and the spectral reflectance curve of the glass substrate with the resin film, and was normalized so that the internal transmittance at the maximum absorption wavelength was 10%.

[0197] The spectral properties are shown in the following table.

[0198] Note that Examples 1-1 to 1-3 are examples, and Examples 1-4 to 1-10 are comparative examples.

[0199] 50%-50% Absorption width: The absolute value (nm) of the difference between the shortest wavelength and the second shortest wavelength at which the internal transmittance is 50% in the range of wavelengths of 600 nm or more

[0200] Table 2

[0201] As shown in Examples 1-1 to 1-3, compared with compounds 4 to 10, compounds 1 to 3 maintain high transmittance of blue light and green light in the spectrum in the resin, and show wide-range absorption properties of near-infrared light.

[0202] < Spectral properties of the resin film >

[0203] <Example 2-1 to Example 2-12>

[0204] A polyimide resin (C-3G30G manufactured by Mitsubishi Gas Chemical Company, Inc.) was dissolved in an organic solvent (cyclohexanone: γ-butyrolactone = 1:1 by mass) at a concentration of 8.5% by mass. The NIR dye (A) and the NIR dye (B) shown in the following table were added to the resin solution so that the NIR dye (A) and the NIR dye (B) were the amounts (mass parts) shown in the following table with respect to 100 mass parts of the resin, and stirring was performed while heating at 50°C for 2 hours. The resin solution containing the dyes was coated on a glass substrate (alkali glass, D263 manufactured by SCHOTT) and dried, thereby obtaining a resin film having a film thickness of 1 μm.

[0205] The spectral internal transmittance curve was calculated using the spectral transmittance curve and the spectral reflectance curve of the glass substrate with the resin film, and was normalized in such a manner that the internal transmittance at the maximum absorption wavelength was 10%.

[0206] The spectral characteristics are shown in the following table.

[0207] In addition, the spectral transmittance curves of the resin films of Example 2-1, Example 2-7, and Example 2-12 are shown in Figure 5 .

[0208] Note that Examples 2-1 to 2-4 are examples, and Examples 2-5 to 2-12 are comparative examples.

[0209] Table 3

[0210] The resin films of Example 2-1 to Example 2-4 using the NIR dye compounds 1 to 3 having excellent spectral characteristics in the resin as shown in Example 1-1 to Example 1-3 are excellent in spectral characteristics even with a small amount of the dye, that is, excellent in transmittance of blue light, and excellent in blocking of near-infrared light.

[0211] <Manufacture of Dielectric Multilayer Film>

[0212] A reflection layer including a dielectric multilayer film of 42 layers obtained by alternately laminating a TiO2 film and a SiO2 film was designed. With respect to the reflection layer, simulation was performed with the number of laminated layers of the dielectric multilayer film, the film thickness of the TiO2 film, and the film thickness of the SiO2 film as parameters, and was designed so as to satisfy the following conditions in each of the spectral transmittance curves under the conditions that the incident angle was 0 degrees and 30 degrees.

[0213] (iv-1) the wavelength at which the transmittance was 50% was in the wavelength range of 600 nm to 850 nm; (iv-2) the wavelength at which the transmittance was 50% was in the wavelength range of 385 nm to 425 nm; (iv-3) the average transmittance of light in the wavelength range of 435 nm to 650 nm is 88% or more; (iv-4) the average transmittance of light in the wavelength range of 750 nm to 1000 nm is 10% or less.

[0214] The spectral characteristics of the obtained reflection layer are shown in the following table.

[0215] Table 4

[0216] Spectral characteristics of the filter

[0217] Example 3-1

[0218] The spectral characteristics of the filter in which the resin film obtained in Example 2-1 was formed on one principal surface of a glass substrate and the reflection layer containing the above-described dielectric multilayer film was formed on the other principal surface were estimated by multiplying the internal transmittance of the resin film at each wavelength in the wavelength range of 350 nm to 1200 nm by the transmittance of the reflection layer at each wavelength.

[0219] Example 3-2

[0220] The spectral characteristics of the filter were estimated in the same manner as in Example 3-1 except that the resin film was changed to the resin film obtained in Example 2-7.

[0221] Example 3-3

[0222] The spectral characteristics of the filter were estimated in the same manner as in Example 3-1 except that the resin film was changed to the resin film obtained in Example 2-12.

[0223] The spectral characteristics are shown in the following table.

[0224] Note that Example 3-1 is an embodiment, and Examples 3-2 and 3-3 are comparative examples.

[0225] Table 5

[0226] The filter of Example 3-1 has high visible light transmittance and suppresses the decrease in near-infrared light blocking property at a high incident angle by having the resin film using Compound 1 that has a high transmittance of blue light and green light in the spectrum of the resin and exhibits a wide range of absorption characteristics of near-infrared light.

[0227] The filter of Example 3-2 resulted in low visible light transmittance.

[0228] The filter of Example 3-3 does not contain a NIR dye that exhibits a wide range of absorption characteristics of near infrared light, and light leakage occurs at a high angle of incidence, and near infrared light blocking properties are reduced.

[0229] <Light resistance test>

[0230] <Examples 4-1 to 4-2>

[0231] A glass substrate with a resin film was produced using each of the compounds shown in the following table in the same manner as in Example 1-1 (spectral characteristics of the dye (A) in the resin).

[0232] A light resistance test sample was produced by forming a reflection layer containing a dielectric multilayer film of 42 layers by alternately laminating a TiO2 layer and a SiO2 layer on the surface of the resin film not in contact with the glass plate.

[0233] In the light resistance test, a super xenon weather meter SX75 (manufactured by Shukichi Test Machine Co., Ltd., product name) was used to irradiate light from the dielectric multilayer film surface of the sample under the following conditions.

[0234] Wavelength: 300 nm to 400 nm

[0235] Temperature: 40°C

[0236] Humidity: 50% RT

[0237] Cumulative light amount: 6.0 kw·hour / m 2

[0238] The spectral transmittance curve before and after irradiation was measured, and the dye residual rate was calculated according to the following formula.

[0239] Dye residual rate [%] = [absorbance at the maximum absorption wavelength after irradiation / absorbance at the maximum absorption wavelength before irradiation] x 100

[0240] The evaluation criterion was that if the dye residual rate was 70% or more, the light resistance was evaluated as excellent.

[0241] The results are shown in the following table.

[0242] Note that Example 4-1 is an example, and Example 4-2 is a comparative example.

[0243] Table 6

[0244] As can be seen from the above results, in the case of using Compound 1 that exhibits excellent spectral characteristics in the resin, the light resistance is also excellent.

[0245] The present application has been described in detail and with reference to specific embodiments, but various changes or modifications can be made without departing from the spirit and scope of the present application, which will be apparent to those skilled in the art. This application is based on Japanese Patent Application (Japanese Patent Application No. 2020-128622) filed on July 29, 2020, the contents of which are incorporated herein by reference.

[0246] Industrial applicability

[0247] The optical filter of the present application has good near-infrared light blocking properties and visible light transmittance, particularly blue light transmittance, while maintaining good near-infrared light blocking properties, particularly suppressing a decrease in near-infrared light blocking properties at high incident angles. It is useful in the use of information acquisition devices such as cameras for conveyors, sensors, and the like, which have been advancing in performance in recent years.

[0248] Explanation of reference numerals

[0249] 1A, 1B, 1C, 1D, … optical filter, 10 … base material, 11 … support, 12 … resin film, 30 … dielectric multilayer film.

Claims

1. A filter having a substrate and a dielectric multilayer film laminated on at least one main surface side of the substrate, wherein, 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 The filter satisfies all of the following spectral characteristics (iii-1) to (iii-3): (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%; (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%; (iii-3) Average transmittance T in the wavelength range of 435 nm to 480 nm in the spectral transmittance curve at an incident angle of 30 degrees. 435-480(30°)(AVE) It is over 85%. The pigment (A) is a compound represented by the following formula (A). The symbols in equation (A) are as follows: 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. Equation (A) may optionally have Z, where Z is a quinary or hexagram. X - Indicates PF6 - [Rf-SO2] - [N(Rf-SO2)2] - Or BF4 - Rf indicates an alkyl group substituted with at least one fluorine atom. R 8 It can be 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 10 It indicates an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms that may have substituents.

2. The filter as described in claim 1, wherein, 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: (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%; (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%; (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.

3. The filter as described in claim 1, wherein, The resin film further comprises a pigment (B), which has a maximum absorption wavelength in dichloromethane in the range of 650 nm to 730 nm, and The resin film satisfies all of the following spectral characteristics (ii-1) to (ii-4): (ii-1) When the content of pigment (A) in the resin film is set to [A] (mass%) and the content of pigment (B) is set to [B] (mass%), [A] / [B]<0.85; (ii-2) Internal transmittance T at a wavelength of 700 nm 700 Less than 5%; (ii-3) Average internal transmittance T in the wavelength range of 730 nm to 800 nm in the spectral transmittance curve 730-800(AVE) Below 25%; (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%.

4. The filter as described in claim 3, wherein, The pigment (B) is squaric acid. Salt pigment.

5. The filter as described in claim 1, wherein, The substrate includes a support and the resin film, and the resin film is laminated on at least one main surface of the support.

6. The filter as described in claim 5, wherein, The support is made of glass or absorbent glass.

7. The filter as claimed in claim 1, wherein, The resin comprises a polyimide resin.

8. An imaging device, wherein, The imaging device includes the filter as described in claim 1.

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