Optical filter

Abstract

To provide an optical filter which is excellent in permeability of visible light and shielding property of near-infrared rays, and has large steepness of permeability change in a boundary region between the visible light and the near-infrared rays.SOLUTION: An optical filter has a base material and a dielectric multilayer film, wherein the base material has an absorption layer (1) containing a near-infrared absorbing dye (1) having a maximum absorption wavelength in a wavelength region of 690-740 nm and a resin, and an absorption layer (2) containing a near-infrared absorbing dye (2) having a maximum absorption wavelength in a wavelength region of more than 740 nm and 870 nm or less and a resin, and at least one of the absorption layer (1) and the absorption layer (2) contains SiO2 fine particles having an average primary particle diameter of 100 nm or less, and the optical filter satisfies all of specific spectral characteristics (i-1) to (i-7).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an optical filter that blocks light in the near-infrared wavelength region. [Background technology]

[0002] In imaging devices using solid-state image sensors, optical filters are used to transmit visible light (hereinafter also referred to as "visible light") and block near-infrared light (hereinafter also referred to as "near-infrared light") in order to reproduce colors well and obtain sharp images. As such optical filters, a near-infrared light cut filter is known, which combines an absorption layer containing a near-infrared absorbing dye and a reflective layer made of a dielectric multilayer film that blocks near-infrared light by reflection.

[0003] Furthermore, to improve image characteristics, greater shielding of near-infrared light is required. To achieve this, attempts are being made, for example, to combine near-infrared absorbing dyes with different maximum absorption wavelengths in the absorption layer. Patent Document 1 describes an optical filter comprising an absorption layer containing a near-infrared absorbing dye having a maximum absorption wavelength in the 700 nm wavelength band, in addition to a near-infrared absorbing dye having a maximum absorption wavelength in the 800 nm wavelength band. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2019 / 022069 [Overview of the project] [Problems that the invention aims to solve]

[0005] The optical filter described in Patent Document 1 improves the shielding performance in the near-infrared band by including a near-infrared absorbing dye having its maximum absorption wavelength in the 800 nm wavelength band. However, dyes with maximum absorption wavelengths in the longer wavelength band tend to absorb visible light as well, which may reduce the overall transmittance of visible light in the optical filter. Furthermore, as a spectral characteristic required for near-infrared light cut-off filters, it is preferable that the change in transmittance in the 650 nm wavelength band, which is the boundary region between visible light and near-infrared light, is steep, from the viewpoint of more efficiently transmitting visible light and more efficiently blocking near-infrared light. However, the optical filter described in Patent Document 1 has low steepness, and there was room for improvement in its spectral characteristics.

[0006] Therefore, the present invention aims to provide an optical filter that exhibits excellent transmittance of visible light and shielding of near-infrared light, and has a steep change in transmittance in the boundary region between visible light and near-infrared light. [Means for solving the problem]

[0007] The present invention provides an optical filter having the following configuration. [1] An optical filter comprising a substrate and a dielectric multilayer film, The substrate has an absorption layer (1) containing a near-infrared absorbing dye (1) and resin having a maximum absorption wavelength in the wavelength region of 690 to 740 nm, and an absorption layer (2) containing a near-infrared absorbing dye (2) and resin having a maximum absorption wavelength in the wavelength region of 740 nm to 870 nm. At least one of the absorption layer (1) and absorption layer (2) contains SiO2 fine particles with an average primary particle diameter of 100 nm or less. The optical filter is an optical filter that satisfies all of the following spectral characteristics (i-1) to (i-7). (i-1) Average transmittance T at an incident angle of 0 degrees in the range of 430-580 nm 430-580(0deg)AVE over 85% (i-2) Average transmittance T at an incident angle of 0 degrees in the range of 580-660 nm 580-660(0deg)AVE over 60% (i-3) Average transmittance T at an incident angle of 0 degrees in the range of 710-730 nm 710-730(0deg)AVE less than 5% (i-4) Average transmittance T at an incident angle of 0 degrees in the range of 830-850 nm 830-850(0deg)AVE less than 5% (i-5) Wavelength IR at which transmittance is 10% at an incident angle of 0 degrees in the 550~700nm range. 10(0deg)and the wavelength IR at which the transmittance is 75% 75(0deg) and the difference Δ(IR 10(0deg) -IR 75(0deg) ) is 80 nm or less (i-6) The average transmittance T at an incident angle of 50 degrees at 710 to 730 nm 710-730(50deg)AVE is 5% or less (i-7) The average transmittance T at an incident angle of 50 degrees at 830 to 850 nm 830-850(50deg)AVE is 5% or less

Advantages of the Invention

[0008] According to the present invention, an optical filter excellent in visible light transmittance and near-infrared light shielding property, and having a large steepness of transmittance change in the boundary region between visible light and near-infrared light can be provided.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an example of an optical filter according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view schematically showing another example of an optical filter according to an embodiment. [Figure 3] FIG. 3 is a diagram showing the spectral transmittance curves of the absorption layers of Example 2-2 and Example 2-4. [Figure 4] FIG. 4 is a diagram showing the spectral transmittance curve of the optical filter of Example 3-2. [Figure 5] FIG. 5 is a diagram showing the spectral transmittance curve of the optical filter of Example 3-3. [Figure 6] FIG. 6 is a diagram showing the spectral transmittance curves of the optical filters of Example 3-1 and Example 3-3.

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described.

[0011] <Optical Filter> The optical filter of the present invention (hereinafter also referred to as "this filter") comprises a substrate and a dielectric multilayer film. The substrate has an absorption layer (1) containing a near-infrared absorbing dye (1) and a resin having a maximum absorption wavelength in the wavelength region of 690 to 740 nm, and an absorption layer (2) containing a near-infrared absorbing dye (2) and a resin having a maximum absorption wavelength in the wavelength region of 740 nm to 870 nm. Furthermore, at least one of the absorption layer (1) and the absorption layer (2) contains SiO2 fine particles with an average primary particle diameter of 100 nm or less, and the optical filter satisfies specific spectral characteristics described later.

[0012] An example of the configuration of this filter will be explained using the drawings. Figures 1 and 2 are schematic cross-sectional views showing an example of an optical filter according to one embodiment.

[0013] The optical filter 1 shown in Figure 1 comprises a substrate 10 and a dielectric multilayer film 31 laminated on one main surface side of the substrate 10. The substrate 10 comprises a support 11 and absorption layers 1A and 2A laminated on one main surface side of the support. The dielectric multilayer film 31 may be laminated on top of absorption layer 2A, although this is not shown. Furthermore, the lamination order of absorption layers 1A and 2A is not limited to that shown in Figure 1.

[0014] The optical filter 1 shown in Figure 2 further comprises a dielectric multilayer film 32 laminated on the other main surface side of the substrate 10.

[0015] <Base material> The substrate of the optical filter of the present invention comprises an absorption layer (1) containing a near-infrared absorbing dye (1) and a resin having a maximum absorption wavelength in the wavelength region of 690 to 740 nm, and an absorption layer (2) containing a near-infrared absorbing dye (2) and a resin having a maximum absorption wavelength in the wavelength region of 740 nm to 870 nm. At least one of the absorption layer (1) and the absorption layer (2) contains SiO2 fine particles with an average primary particle diameter of 100 nm or less.

[0016] By using two near-infrared absorbing dyes (1) and (2) with different maximum absorption wavelengths, near-infrared light can be absorbed over a wide range. Here, it is preferable that the near-infrared absorbing dye is uniformly dispersed in the resin. When the dye aggregates, there is a risk of an increase in haze, a broadening of the absorption band, and a decrease in the transmittance in the visible light region. By coexisting SiO2 fine particles with the near-infrared absorbing dye, the dye can be adsorbed on the surface of the SiO2 fine particles, preventing aggregation in the resin.

[0017] In addition, since the longer the maximum absorption wavelength, the more likely it is to be involved in the decrease in the transmittance in the visible light region, it is preferable that the absorption layer (2) containing the near-infrared absorbing dye (2) contains SiO2 fine particles in terms of facilitating the exhibition of the effects of the present invention.

[0018] <SiO2 fine particles> The absolute value Ra of the difference between the Hansen solubility parameter (hereinafter, also referred to as "HSP") of the SiO2 fine particles and the Hansen solubility parameter of the near-infrared absorbing dye (2) IR is preferably 10 or less. HSP is the solubility parameter of Hildebrand divided into three cohesive energy components: a dispersion term component, a polarization term component, and a hydrogen bond term component, and is a parameter of a vector quantity indicating the compatibility of substances. In this specification, the dispersion term component of HSP is δ d , the polarization term component is δ p , and the hydrogen bond component is δ h These three parameters are regarded as coordinates in three-dimensional space. When the HSPs of two substances are placed in three-dimensional space, the smaller the distance between the two points, the higher the affinity between the two substances. Here, the absolute value Ra IR is represented by the following mathematical formula (A), and the smaller Ra IR , the higher the affinity between the SiO2 fine particles and the near-infrared absorbing dye (2). Ra IR = [4×(δd p - δd d ) 2 + (δp p - δp d ) 2 + (δh p - δh d ) 2 ​1 / 2 (A) (The meaning of each symbol in the formula is as follows.) δd p : Dispersion term of the Hansen solubility parameter for SiO2 fine particles δp p Polarization term of the Hansen solubility parameter for SiO2 fine particles δh p :Hansen solubility parameter of SiO2 fine particles, hydrogen bonding term δd d : Dispersion term of the Hansen solubility parameter for near-infrared absorbing dyes (2) δp d : Polarization term of Hansen solubility parameter for near-infrared absorbing dyes (2) δh d (Hansen solubility parameter of near-infrared absorbing dyes (2) - hydrogen bonding term)

[0019] The SiO2 fine particles in this invention are the same as the above Ra IR Ra is preferably 10 or less, more preferably 8.5 or less. IR If the value is 10 or less, the affinity with the near-infrared absorbing dye (2) is sufficient, allowing the near-infrared absorbing dye (2) to be adsorbed onto the surface of the SiO2 fine particles and suppressing the aggregation of the dye.

[0020] The HSPs (δd, δp, δh) of a substance can be calculated by dissolving it in several solvents with known HSPs and inputting the solubility results into HSP calculation software. The HSP of a substance can also be calculated by inputting the SMILES format of its chemical structure into HSP calculation software.

[0021] SiO2 fine particles typically have hydroxyl groups on their surface, but SiO2 fine particles with an epoxy structure on their surface or SiO2 fine particles with a highly hydrophobic surface treatment may also be used. SiO2 fine particles that retain hydroxyl groups have a hydrophilic surface, which can lead to water absorption and a decrease in the moisture resistance of the absorbent layer, which is a resin film. SiO2 fine particles with a hydrophobic surface modified with functional groups are preferable because they do not absorb water themselves and are less prone to aggregation, thus avoiding a decrease in haze.

[0022] Examples of SiO2 fine particles include any shape, such as spherical, plate-like, columnar, fibrous, needle-like, irregularly shaped, or porous particles.

[0023] The SiO2 fine particles have an average primary particle diameter of 100 nm or less, preferably 50 nm or less, and more preferably 30 nm or less, from the viewpoint of suppressing the increase in haze of the optical filter. Furthermore, from the viewpoint of preventing aggregation of primary particles, it is preferably 5 nm or larger. A primary particle diameter of 5 nm or larger is preferable because the cohesive force between particles increases, and there is no concern about an increase in haze due to the formation of secondary aggregates.

[0024] The average primary particle size of SiO2 fine particles is mainly measured based on the BET method.

[0025] The content of SiO2 fine particles in the absorption layer is preferably 5% by mass or more, more preferably 25% by mass or more, from the viewpoint of sufficiently suppressing the aggregation of near-infrared absorbing dyes. Furthermore, from the viewpoint of maintaining a good appearance such as the smoothness of the absorption layer and suppressing the aggregation of the fine particles themselves, it is preferably 99% by mass or less, more preferably 80% by mass or less.

[0026] The absorption layer may also contain inorganic fine particles other than SiO2 fine particles. From the viewpoint of low reactivity with dyes, preferred types of inorganic fine particles include SiO2, alumina, zirconia, aluminosilicate, kaolinite, zinc oxide, titanium oxide, CsWO3, and LaB6, with SiO2, alumina, and titanium oxide being more preferred. These may be used individually or in combination of two or more types.

[0027] <Near-infrared absorbing dye (1)> The near-infrared absorbing dye (1) has its maximum absorption wavelength in the wavelength range of 690 to 740 nm. Here, the maximum absorption wavelength is the wavelength in the resin used in the absorbing layer (1).

[0028] Examples of the near-infrared absorbing dye (1) include at least one selected from the group consisting of cyanine dyes, phthalocyanine dyes, squarylium dyes, and naphthalocyanine dyes, which can be used individually or in combination. Among these, squarylium dyes are preferred from the viewpoint of easily exhibiting the effects of the present invention.

[0029] <Squalirium pigment> The squarylium dye is preferably a compound represented by the following formula (I) or formula (II). Furthermore, if two or more identical symbols exist in a squarylium dye compound, the definitions of those symbols may be the same or different.

[0030] <Squallium compound (I)>

[0031] [ka]

[0032] However, the definitions of the symbols in the above formula are as follows: R 24 and R 26 Each of these independently consists of a hydrogen atom, a halogen atom, a hydroxyl group, a C1-C20 alkyl or alkoxy group, a C1-C10 acyloxy group, a C6-C11 aryl group, a C7-C18 alaryl group which may have substituents and may have oxygen atoms between carbon atoms, and -NR 27 R 28 (R 27 and R 28 These are, independently, a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and -C(=O)-R 29 (R 29 (This may include hydrogen atoms, halogen atoms, hydroxyl groups, hydrocarbon groups having 1 to 25 carbon atoms that may have substituents, unsaturated bonds between carbon atoms, oxygen atoms, or saturated or unsaturated ring structures), -NHR 30 , or -SO2-R 30 (R 30(R) represents a hydrocarbon group having 1 to 25 carbon atoms, in which each hydrogen atom may be substituted with a halogen atom, hydroxyl group, carboxyl group, sulfo group, or cyano group, and which may contain unsaturated bonds, oxygen atoms, or saturated or unsaturated ring structures between carbon atoms. ) or a group represented by the following formula (S) (R) 41 , R 42 k independently represents a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 10 carbon atoms. k is 2 or 3.

[0033] [ka]

[0034] R 21 and R 22 , R 22 and R 25 , and R 21 and R 23 These may be linked together to form heterocycles A, B, and C, respectively, with nitrogen atoms, each having a membership of 5 or 6. R when a heteroalgebra A is formed 21 and R 22 This represents an alkylene group or alkylene oxy group in which the hydrogen atom may be substituted with an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an acyloxy group having 1 to 10 carbon atoms that may have substituents, as the divalent group -Q- to which these are bonded. R when a heteroalgebra B is formed 22 and R 25 , and R when a heterocyclic ring C is formed 21 and R 23 These are the divalent groups -X to which they are bonded. 1 -Y 1 -and -X 2 -Y 2 -(The side that bonds to nitrogen is X) 1 and X 2 ) as X 1 and X 2 These are the groups represented by the following formulas (1x) or (2x), and Y 1 and Y 2is a group represented by any one selected from the following formulas (1y) to (5y). X 1 and X 2 are groups represented by the following formula (2x), Y 1 and Y 2 may each be a single bond, and in that case, an oxygen atom may be present between carbon atoms.

[0035]

Chemical formula

[0036] In formula (1x), the four Zs are each independently a hydrogen atom, a hydroxyl group, an alkyl group or an alkoxy group having 1 to 6 carbon atoms, or -NR 38 R 39 (R 38 and R 39 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms). R 31 ~R 36 are each independently 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. R 27 、R 28 、R 29 、R 31 ~R 37 、when not forming a heterocyclic ring, R 21 ~R 23 、and R 25 may be bonded to any other of these to form a 5-membered or 6-membered ring. R 31 and R 36 、R 31 and R 37 may be directly bonded. When not forming a heterocyclic ring, R 21 、R 22 、R 23 and R 25Each of these independently represents a hydrogen atom, a halogen atom, a hydroxyl group, a C1-C20 alkyl or alkoxy group, a C1-C10 acyloxy group, a C6-C11 aryl group, or a C7-C18 alaryl group which may have substituents or oxygen atoms between carbon atoms.

[0037] Examples of compound (I) include compounds represented by any of formulas (I-1) to (I-3), and from the viewpoint of solubility in the resin, heat resistance and light resistance in the resin, and visible light transmittance of the resin layer containing it, the compound represented by formula (I-1) is particularly preferred.

[0038] [ka]

[0039] The symbols in formulas (I-1) to (I-3) are the same as those specified for the same symbols in formula (I), and the preferred embodiments are also the same.

[0040] In compound (I-1), X 1 As for the base, (2x) is preferred, Y 1 A single bond or group (1y) is preferred. In this case, R 31 ~R 36 Preferably, it is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom or a methyl group. 1 -X 1 Specifically, examples include the divalent organic groups shown in formulas (11-1) to (12-3).

[0041] -C(CH3)2-CH(CH3)- …(11-1) -C(CH3)2-CH2- …(11-2) -C(CH3)2-CH(C2H5)- …(11-3) -C(CH3)2-C(CH3)(nC3H7)- …(11-4) -C(CH3)2-CH2-CH2- …(12-1) -C(CH3)2-CH2-CH(CH3)- …(12-2) -C(CH3)2-CH(CH3)-CH2- …(12-3)

[0042] Furthermore, in compound (I-1), R 21 From the viewpoint of solubility, heat resistance, and the steepness of the change near the boundary between the visible and near-infrared regions in the spectral transmittance curve, the group represented by formula (4-1) or (4-2) is independently more preferred.

[0043] [ka]

[0044] In equations (4-1) and (4-2), R 71 ~R 75 This independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms.

[0045] In compound (I-1), R 24 -NR 27 R 28 Preferably. -NR 27 R 28 From the perspective of solubility in resins and coating solvents, -NH-C(=O)-R 29 or -NH-SO2-R 30 It is preferable.

[0046] <Squallium compound (II)>

[0047] [ka]

[0048] However, the definitions of the symbols in the above formula are as follows: Each ring Z is independently a 5-membered or 6-membered ring having 0 to 3 heteroatoms in the ring, and the hydrogen atoms in ring Z may be substituted. R 1 and R 2 , R 2 and R3 , and R 1 The carbon atoms or heteroatoms constituting ring Z may be linked to each other and form heterorings A1, B1, and C1, respectively, together with the nitrogen atom, in which case the hydrogen atoms in heterorings A1, B1, and C1 may be substituted. 1 and R 2 Each of these independently represents a hydrocarbon group which may contain an unsaturated bond, heteroatom, saturated or unsaturated ring structure between a hydrogen atom, a halogen atom, or carbon atoms, and which may have substituents. 4 and R when it does not form a heterocycle 3 Each of these independently represents an alkyl or alkoxy group which may contain a hydrogen atom, a halogen atom, or a heteroatom between carbon atoms, and which may have substituents.

[0049] Examples of compound (II) include compounds represented by any of formulas (II-1) to (II-3), and from the viewpoint of solubility in the resin and visible light transmittance in the resin, the compound represented by formula (II-3) is particularly preferred.

[0050] [ka]

[0051] In formula (II-1) and formula (II-2), R 1 and R 2 Each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 15 carbon atoms which may have substituents, and R 3 ~R 6 Each of these independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 10 carbon atoms, which may have substituents.

[0052] In formula (II-3), R 1 , R 4 , and R 9 ~R 12Each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 15 carbon atoms which may have substituents, and R 7 and R 8 Each of these independently represents a hydrogen atom, a halogen atom, or a C1-C5 alkyl group which may have substituents.

[0053] R in compound (II-1) and compound (II-2) 1 and R 2 From the viewpoint of solubility in resin, visible light transmittance, etc., an alkyl group having 1 to 15 carbon atoms is preferred, and an alkyl group having 7 to 15 carbon atoms is more preferred, R 1 and R 2 At least one of them is more preferably an alkyl group having a branched chain with 7 to 15 carbon atoms, R 1 and R 2 Alkyl groups having branched chains with 8 to 15 carbon atoms are particularly preferred for both.

[0054] R in compound (II-3) 1 From the viewpoint of solubility in transparent resins and visible light transmittance, alkyl groups having 1 to 15 carbon atoms are preferred, alkyl groups having 1 to 10 carbon atoms are more preferred, and ethyl groups and isopropyl groups are particularly preferred.

[0055] R 4 From the viewpoint of visible light transmittance and ease of synthesis, hydrogen atoms and halogen atoms are preferred, with hydrogen atoms being particularly preferred. R 7 and R 8 The following are preferred independently: a hydrogen atom, a halogen atom, and a C1-C5 alkyl group which may be substituted with a halogen atom; a hydrogen atom, a halogen atom, and a methyl group are more preferred.

[0056] R 9 ~R 12 The following are preferred independently: a hydrogen atom, a halogen atom, and a C1-C5 alkyl group which may be substituted with a halogen atom. -CR 9 R 10 -CR 11 R 12-Examples include the divalent organic groups represented by the following groups (13-1) to (13-5). -CH(CH3)-C(CH3)2- …(13-1) -C(CH3)2-CH(CH3)- …(13-2) -C(CH3)2-CH2- …(13-3) -C(CH3)2-CH(C2H5)- …(13-4) -CH(CH3)-C(CH3)(CH2-CH(CH3)2)-…(13-5)

[0057] Compounds (I) and (II) can each be prepared by known methods. Compound (I) can be prepared by the methods described in U.S. Patent No. 5,543,086, U.S. Patent Publication No. 2014 / 0061505, and International Publication No. 2014 / 088063. Compound (II) can be prepared by the methods described in International Publication No. 2017 / 135359.

[0058] <Resin in the absorption layer (1)> The resin used in the absorbent layer (1) is not limited to transparent resins, and one or more transparent resins selected from polyester resin, acrylic resin, epoxy resin, ene-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polyparaphenylene resin, polyarylene ether phosphine oxide resin, polyamide resin, polyimide resin, polyamide-imide resin, polyolefin resin, cyclic olefin resin, polyurethane resin, and polystyrene resin can be used. These resins may be used individually or in mixtures of two or more. From the viewpoint of the spectral characteristics of the absorption layer, glass transition temperature (Tg), and adhesion, one or more resins selected from polyimide resin, polycarbonate resin, polyester resin, and acrylic resin are preferred.

[0059] <Near-infrared absorbing dye (2)> The near-infrared absorbing dye (2) has a maximum absorption wavelength in the wavelength range between 740 nm and 870 nm. Here, the maximum absorption wavelength is the wavelength in the resin used in the absorbing layer (2).

[0060] Examples of the near-infrared absorbing dye (2) include at least one selected from the group consisting of cyanine dyes, phthalocyanine dyes, squarylium dyes, and naphthalocyanine dyes, which can be used individually or in combination. Among these, cyanine dyes are preferred from the viewpoint of easily exhibiting the effects of the present invention.

[0061] <Cyanine pigment> The cyanine dye is preferably a compound represented by any of the following formulas (III) to (V).

[0062] <Cyanine compounds (III), (IV), (V)>

[0063] [ka]

[0064] [ka]

[0065] However, the symbols in the above formula are as follows: R 101 ~R 111 and R 121 ~R 131 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 15 carbon atoms (which may have substituents), or an aryl group having 5 to 20 carbon atoms. Y represents a halogen atom or an optionally substituted phenyl group. X - This indicates a monovalent anion. n1 and n2 are either 0 or 1. -(CH2) n1 -Carbon rings containing -(CH2) n2The hydrogen atom bonded to the carbon ring containing - may be substituted with a halogen atom, a C1-C15 alkyl group which may have substituents, or a C5-C20 aryl group.

[0066] In the above, the alkyl group (including the alkyl group of the alkoxy group) may be linear, branched, or saturated. The aryl group is a group that is bonded via carbon atoms constituting the aromatic ring of an aromatic compound, such as a benzene ring, naphthalene ring, biphenyl, furan ring, thiophene ring, pyrrole ring, etc. Substituents in C1-C15 alkyl or alkoxy groups, or C5-C20 aryl groups, which may have substituents, include halogen atoms and C1-C10 alkoxy groups.

[0067] In equations (III) to (V), R 101 and R 121 The alkyl group is preferably a C1-C15 alkyl group or a C5-C20 aryl group, and a branched C1-C15 alkyl group is more preferred from the viewpoint of maintaining high visible light transmittance in the resin.

[0068] In equations (III) to (V), R 102 ~R 105 , R 108 , R 109 , R 110 , R 111 , R 122 ~R 127 , R 130 and R 131 Each of these is preferably an independent hydrogen atom, an alkyl or alkoxy group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms, with hydrogen atoms being more preferred from the viewpoint of obtaining high visible light transmittance.

[0069] In formulas (III) and (IV), the halogen atom in Y can be a fluorine atom, a chlorine atom, or a bromine atom. When Y is a phenyl group, the substituent can be an alkyl group having 1 to 15 carbon atoms. From the viewpoint of obtaining high visible light transmittance, a chlorine atom or a phenyl group is more preferable for Y.

[0070] R 106 , R 107 , R 128 and R 129 Each of these is preferably a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms (which may include linear, cyclic, or branched alkyl groups), and more preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms. 106 and R 107 , R 128 and R 129 The same group is preferable.

[0071] X - As for, I - BF4 - PF6 - ClO4 - Examples include anions represented by formulas (X1) and (X2), preferably BF4 - , or PF6 - That is the case.

[0072] [ka]

[0073] Dyes (III), (IV), and (V) can be produced by methods described, for example, in Dyes and Pigments 73 (2007) 344-352 and J. Heterocyclic Chem, 42, 959 (2005).

[0074] <Resin in the absorption layer (2)> The resin used in the absorbent layer (2) is not limited to transparent resins, and one or more transparent resins selected from polyester resin, acrylic resin, epoxy resin, ene-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, poly-paraphenylene resin, polyarylene ether phosphine oxide resin, polyamide resin, polyimide resin, polyamide-imide resin, polyolefin resin, cyclic olefin resin, polyurethane resin, and polystyrene resin can be used. These resins may be used individually or in combination of two or more.

[0075] From the viewpoints of the spectral characteristics of the absorption layer, the glass transition temperature (Tg), adhesion, and the ability to improve the dispersibility of the dye, epoxy resins are particularly preferred. The epoxy resin is not particularly limited as long as it is a resin obtained by polymerizing epoxy compounds as constituent components (monomers). From the viewpoint of improving the dispersibility of the dye, epoxy resins with a molecular weight of 10,000 or less are preferred. Examples of epoxy compounds include alicyclic epoxy compounds, hydrogenated epoxy compounds, aromatic epoxy compounds, or aliphatic epoxy compounds. Furthermore, from the viewpoint of transparency, heat resistance, and light resistance, the epoxy resin is preferably a resin obtained by polymerizing alicyclic epoxy compounds.

[0076] The content of the near-infrared absorbing dye (1) in the absorption layer (1) is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 15 parts by mass, per 100 parts by mass of resin. When two or more compounds are combined, the above content is the sum of the individual compounds.

[0077] The content of the near-infrared absorbing dye (2) in the absorption layer (2) is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 15 parts by mass, per 100 parts by mass of resin. When two or more compounds are combined, the above content is the sum of the content of each compound.

[0078] At least one of the absorbing layer (1) and absorbing layer (2) may contain other dyes, such as ultraviolet light absorbing dyes, as long as they do not impair the effects of the present invention. Examples of ultraviolet light absorbing dyes include oxazole dyes, merocyanine dyes, cyanine dyes, naphthalimide dyes, oxadiazole dyes, oxazine dyes, oxazolidine dyes, naphthalic acid dyes, styryl dyes, anthracene dyes, cyclic carbonyl dyes, and triazole dyes.

[0079] The substrate material in this filter can be any transparent material that transmits visible light, whether organic or inorganic, and is not particularly limited. A composite substrate is preferred, in which an absorbent layer (1) and an absorbent layer (2) are laminated on at least one main surface of a support. In this case, the support is preferably made of a resin or an inorganic material.

[0080] The inorganic material can be at least one selected from the group consisting of glass, glass ceramics, quartz, and sapphire, and can be used individually or in combination with other materials.

[0081] The thickness of the support is preferably 400 μm or less, and usually 50 μm or more, from the viewpoint of reducing warping during dielectric multilayer film deposition and reducing the height of the optical filter.

[0082] The absorption layer can be formed by preparing a coating solution by dissolving or dispersing a near-infrared absorbing dye, a resin, SiO2 fine particles, and a polymerization initiator (if necessary) in a solvent, coating this solution onto a support, drying it, and further curing it if necessary. The support may be the support included in this filter, or a releaseable support used only when forming the absorption layer. The solvent may be any dispersion medium or solvent that can stably disperse or dissolve the components. As polymerization initiators, photopolymerization initiators, thermal polymerization initiators, etc., can be used. From the viewpoint of obtaining a coating film with a high degree of polymerization, it is preferable to use a thermal polymerization initiator.

[0083] For coating the coating solution, methods such as immersion coating, cast coating, or spin coating can be used. Before applying the coating solution to the support, the support may be surface-treated using a silane coupling agent or the like to improve adhesion.

[0084] After applying the above coating liquid onto the support, an absorbent layer is formed by drying the coating film or curing it after drying.

[0085] The method for curing the coating film is not particularly limited, and various methods such as thermal curing and photocuring (curing by irradiation with active energy rays) can be suitably used. For thermal curing, curing at around 30 to 400°C is preferable, and for photocuring, 10 to 10,000 mJ / cm² is preferable. 2 It is preferable that the material hardens in this manner. Hardening may be carried out in one stage, or in two stages, such as primary hardening (pre-hardening) and secondary hardening (main hardening). The hardening process can be carried out in air or in an inert gas atmosphere such as nitrogen.

[0086] The thickness of the absorption layer (1) is preferably 0.1 to 20 μm, more preferably 0.3 to 10 μm. The thickness of the absorption layer (2) is preferably 0.1 to 20 μm, more preferably 0.3 to 10 μm.

[0087] The shape of the substrate is not particularly limited and may be in the form of a block, plate, or film.

[0088] In this filter having the above configuration, it is preferable that the substrate satisfies all of the following spectral characteristics (ii-1) to (ii-5). (ii-1) Average internal transmittance T at 430~580nm 430-580AVE over 80% (ii-2) Average internal transmittance T at 580~660nm 580-660AVE over 87% (ii-3) Average internal transmittance T at 710~730nm 710-730AVE less than 20% (ii-4) Average internal transmittance T at 830~850nm 830-850AVE less than 30% (ii-5) Wavelength IR at which internal transmittance is 10% in the 550~700nm range 10 And the wavelength IR with an internal transmittance of 75% 75 The difference Δ(IR) 10 -IR 75 ) 75nm or less

[0089] Satisfying spectral characteristics (ii-1) to (ii-5) means that the material exhibits excellent transmittance of visible light and shielding of near-infrared light, and that the change in transmittance in the boundary region between visible light and near-infrared light is steep.

[0090] Average internal transmittance T 430-580AVE It is more preferably 90% or more. Average internal transmittance T 580-660AVE It is more preferably 87.5% or higher. Average internal transmittance T 710-730AVE It is more preferable to have 15% or less. T 830-850AVE It is more preferable to have 20% or less. Δ(IR 10 -IR 75 ) is more preferably within 73 nm.

[0091] <Dielectric multilayer film> In this filter, it is preferable that the dielectric multilayer film is laminated as the outermost layer on at least one main surface side of the substrate.

[0092] In this filter, it is preferable that at least one of the dielectric multilayer films is designed as a near-infrared reflective layer (hereinafter also referred to as the NIR reflective layer). The other dielectric multilayer film is preferably designed as an NIR reflective layer, a reflective layer having a reflection region other than the near-infrared region, or an anti-reflective layer.

[0093] The NIR reflective layer is a dielectric multilayer film designed to shield near-infrared light. The NIR reflective layer, for example, transmits visible light and has wavelength selectivity to primarily reflect near-infrared light outside the light-shielding region of the resin film, which is the absorption layer. The reflective region of the NIR reflective layer may also include the light-shielding region of the resin film in the near-infrared region. The NIR reflective layer may be designed to further block light in wavelengths other than the near-infrared region, such as the near-ultraviolet region, not just its NIR reflection characteristics.

[0094] The NIR reflective layer is composed of a dielectric multilayer film in which a low refractive index dielectric film (low refractive index film) and a high refractive index dielectric film (high refractive index film) are alternately stacked. The high refractive index film preferably has a refractive index of 1.6 or higher, and more preferably 2.2 to 2.5. Examples of materials for the high refractive index film include Ta2O5, TiO2, TiO, Ti2O3, and Nb2O5. Other commercially available products include OS50 (Ti3O5), OS10 (Ti4O7), OA500 (a mixture of Ta2O5 and ZrO2), and OA600 (a mixture of Ta2O5 and TiO2), all manufactured by Canon Optron. Of these, TiO2 is preferred in terms of film formation properties, reproducibility in refractive index, stability, etc.

[0095] On the other hand, the low refractive index film preferably has a refractive index of less than 1.6, and more preferably 1.45 or more and less than 1.55. Examples of materials for the low refractive index film are SiO2, SiO2, and SiO2. x N y Examples include MgF2. Other commercially available products include S4F and S5F (a mixture of SiO2 and AlO2) manufactured by Canon Optron. SiO2 is preferred in terms of reproducibility, stability, and cost-effectiveness in film formation.

[0096] The NIR reflective layer preferably has a total number of layers of dielectric multilayer films constituting the reflective layer, more preferably 25 layers or more, and even more preferably 30 layers or more, from the viewpoint of light shielding in the near-infrared wavelength region. However, as the total number of layers increases, warping and other issues may occur, and the film thickness may increase, so the total number of layers is preferably 100 layers or less, more preferably 75 layers or less, and even more preferably 60 layers or less. Furthermore, the thickness of the reflective layer is preferably 2 to 10 μm overall from the viewpoint of reducing the warping of the optical filter.

[0097] Furthermore, for the formation of dielectric multilayer films, vacuum deposition processes such as CVD, sputtering, and vacuum evaporation, as well as wet deposition processes such as spraying and dipping, can be used.

[0098] The NIR reflective layer may provide predetermined spectral characteristics with a single layer (a group of dielectric multilayer films) or with two layers. If there are two or more layers, each reflective layer may have the same or different configuration. When there are two or more reflective layers, they are usually composed of multiple reflective layers with different reflection bands. When two reflective layers are provided, one may be a near-infrared reflective layer that blocks light in the short-wavelength band of the near-infrared region, and the other may be a near-infrared / near-ultraviolet reflective layer that blocks light in both the long-wavelength band of the near-infrared region and the near-ultraviolet region.

[0099] Examples of anti-reflective layers include dielectric multilayer films, intermediate refractive index media, and moth-eye structures with gradually changing refractive indices. Among these, dielectric multilayer films are preferred from the viewpoint of optical efficiency and productivity. The anti-reflective layer is obtained by alternately stacking dielectric multilayer films, similar to the reflective layer.

[0100] <Optical filters> The filter having the above configuration is an optical filter with excellent light transmission selectivity that transmits visible light and blocks near-infrared light. The optical filter of the present invention satisfies all of the following spectral characteristics (i-1) to (i-7). (i-1) Average transmittance T at an incident angle of 0 degrees in the range of 430-580 nm 430-580(0deg)AVE over 85% (i-2) Average transmittance T at an incident angle of 0 degrees in the range of 580-660 nm 580-660(0deg)AVE over 60% (i-3) Average transmittance T at an incident angle of 0 degrees in the range of 710-730 nm 710-730(0deg)AVE less than 5% (i-4) Average transmittance T at an incident angle of 0 degrees in the range of 830-850 nm 830-850(0deg)AVE less than 5% (i-5) Wavelength IR at which transmittance is 10% at an incident angle of 0 degrees in the 550~700nm range. 10(0deg) And the wavelength IR with a transmittance of 75% 75(0deg) The difference Δ(IR) 10(0deg) -IR 75(0deg) ) is 80nm or less (i-6) Average transmittance T at an incident angle of 50 degrees in the range of 710-730 nm 710-730(50deg)AVE less than 5% (i-7) Average transmittance T at an incident angle of 50 degrees in the range of 830-850 nm 830-850(50deg)AVE less than 5%

[0101] Satisfying spectral characteristics (i-1) to (i-5) means that the material exhibits excellent transmittance of visible light and shielding of near-infrared light, and that the change in transmittance in the boundary region between visible light and near-infrared light is steep. Satisfying spectral characteristics (i-6) to (i-7) means that the device exhibits excellent shielding of near-infrared light even at high incidence angles.

[0102] Average transmittance T 430-580(0deg)AVE Preferably, it is 86% or more. Average transmittance T 580-660(0deg)AVE Preferably, it is 62% or more. Average transmittance T 710-730(0deg)AVE It is preferably 1.5% or less. Average transmittance T 830-850(0deg)AVE It is preferably 1.5% or less. Δ(IR 10(0deg) -IR 75(0deg) ) is preferably 79 nm or less.

[0103] Average transmittance T 710-730(50deg)AVE It is preferably 1.5% or less. Average transmittance T 830-850(50deg)AVE It is preferably 1.5% or less.

[0104] The optical filter of the present invention preferably further satisfies the following spectral characteristics (i-8). (i-8) Wavelength IR at an incident angle of 0 degrees where the transmittance is 50% in the 550-700nm range. 50(0deg)And the wavelength IR at an incident angle of 50 degrees where the transmittance is 50%. 50(50deg) The difference Δ(IR) 50(0deg) -IR 50(50deg) ) is 20nm or less Satisfying the spectral characteristics (i-8) means that the transmittance of visible light and the shielding of near-infrared light do not depend on the angle of incident light. Δ(IR 50(0deg) -IR 50(50deg) ) is more preferably 10 nm or less.

[0105] The optical filter of the present invention can provide an imaging device with excellent color reproduction when used, for example, in an imaging device such as a digital still camera. Such an imaging device comprises a solid-state image sensor, an imaging lens, and the optical filter of the present invention. The optical filter of the present invention can be used, for example, by being placed between the imaging lens and the solid-state image sensor, or by being directly attached to the solid-state image sensor, imaging lens, etc. of the imaging device via an adhesive layer.

[0106] As described above, this specification discloses the following optical filters, etc. [1] An optical filter comprising a substrate and a dielectric multilayer film, The substrate has an absorption layer (1) containing a near-infrared absorbing dye (1) and resin having a maximum absorption wavelength in the wavelength region of 690 to 740 nm, and an absorption layer (2) containing a near-infrared absorbing dye (2) and resin having a maximum absorption wavelength in the wavelength region of 740 nm to 870 nm. At least one of the absorption layer (1) and absorption layer (2) contains SiO2 fine particles with an average primary particle diameter of 100 nm or less. The optical filter is an optical filter that satisfies all of the following spectral characteristics (i-1) to (i-7). (i-1) Average transmittance T at an incident angle of 0 degrees in the range of 430-580 nm 430-580(0deg)AVE over 85% (i-2) Average transmittance T at an incident angle of 0 degrees in the range of 580-660 nm 580-660(0deg)AVE over 60% (i-3) Average transmittance T at an incident angle of 0 degrees in the range of 710-730 nm 710-730(0deg)AVE less than 5% (i-4) Average transmittance T at an incident angle of 0 degrees in the range of 830-850 nm 830-850(0deg)AVE less than 5% (i-5) Wavelength IR at which transmittance is 10% at an incident angle of 0 degrees in the 550~700nm range. 10(0deg) And the wavelength IR with a transmittance of 75% 75(0deg) The difference Δ(IR) 10(0deg) -IR 75(0deg) ) is 80nm or less (i-6) Average transmittance T at an incident angle of 50 degrees in the range of 710-730 nm 710-730(50deg)AVE less than 5% (i-7) Average transmittance T at an incident angle of 50 degrees in the range of 830-850 nm 830-850(50deg)AVE less than 5% [2] The optical filter according to [1], wherein the substrate satisfies all of the following spectral characteristics (ii-1) to (ii-5). (ii-1) Average internal transmittance T at 430~580nm 430-580AVE over 80% (ii-2) Average internal transmittance T at 580~660nm 580-660AVE over 87% (ii-3) Average internal transmittance T at 710~730nm 710-730AVE less than 20% (ii-4) Average internal transmittance T at 830~850nm 830-850AVE less than 30% (ii-5) Wavelength IR at which internal transmittance is 10% in the 550~700nm range 10 And the wavelength IR with an internal transmittance of 75% 75 The difference Δ(IR) 10 -IR 75 ) 75nm or less [3] The optical filter according to [1] or [2], wherein the absorption layer (2) contains SiO2 fine particles with an average primary particle diameter of 100 nm or less. [4] The optical filter according to any one of [1] to [3], wherein at least one of the resin in the absorption layer (1) and the resin in the absorption layer (2) is an epoxy resin. [5] An optical filter as described in any one of [1] to [4], wherein the haze is 1% or less. [6] The optical filter according to any one of [1] to [5], wherein the content of SiO2 fine particles in the absorption layer (1) or the absorption layer (2) is 5% by mass or more. [7] The optical filter according to any one of [1] to [6], wherein the near-infrared absorbing dye (2) contains a cyanine dye. [8] The optical filter according to any one of [1] to [7], wherein the near-infrared absorbing dye (1) contains a squarylium dye. [9] The absolute value Ra of the difference between the Hansen solubility parameter of the SiO2 fine particles and the Hansen solubility parameter of the near-infrared absorbing dye (2), calculated by the following formula (A): IR An optical filter according to any one of [1] to [8], wherein the value is 10 or less. Ra IR =[4×(δd p -δd d ) 2 +(δp p -δp d ) 2 +(δh p -δh d ) 2 ] 1 / 2 (A) (The meaning of each symbol in the formula is as follows.) δd p : Dispersion term of the Hansen solubility parameter for SiO2 fine particles δp p Polarization term of the Hansen solubility parameter for SiO2 fine particles δh p :Hansen solubility parameter of SiO2 fine particles, hydrogen bonding term δd d : Dispersion term of the Hansen solubility parameter for near-infrared absorbing dyes (2) δp d : Polarization term of Hansen solubility parameter for near-infrared absorbing dyes (2) δh d (Hansen solubility parameter of near-infrared absorbing dyes (2) - hydrogen bonding term)

[10] The optical filter according to any one of [1] to [9], wherein the near-infrared absorbing dye (2) comprises at least one of the cyanine dyes shown in the following formulas (III) to (V).

[0107]

Chem.

[0108]

Chem.

[0109] 〔The symbols in the above formula are as follows. R 101 ~R 111 and R 121 ~R 131 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms. Y represents a halogen atom or a phenyl group which may have a substituent. X - represents a monovalent anion. n1 and n2 are 0 or 1. -(CH2) n1 -containing carbocyclic ring, and the hydrogen atom bonded to the -(CH2) n2 -containing carbocyclic ring may be substituted with a halogen atom, an alkyl group having 1 to 15 carbon atoms which may have a substituent or an aryl group having 5 to 20 carbon atoms.〕 〔11〕 An imaging device provided with the optical filter according to any one of 〔1〕 to 〔10〕.

Examples

[0110] Next, the present invention will be described more specifically by way of examples. For the measurement of each spectral characteristic, an ultraviolet-visible spectrophotometer (manufactured by Hitachi High-Technologies Corporation, UH-4150 model) was used. In addition, the spectral characteristics when the incident angle is not specifically specified are the values measured at an incident angle of 0 degrees (perpendicular to the main surface of the optical filter).

[0111] <SiO2 fine particles> The SiO2 fine particles used in each example are as follows.

[0112]

Table 1

[0113] <Dye> The dye compounds used in each example are as follows. Compound B1 (merocyanine dye): Synthesized based on the specification of German Patent Publication No. 10109243. Compound B2 (squarylium dye): Synthesized based on International Publication No. 2014 / 088063 and International Publication No. 2016 / 133099. Compound B3 (cyanine dye): S0712 manufactured by FEW Chemicals was used. Compound B4 (cyanine dye): Synthesized based on Dyes and Pigments, 73, 344 - 352 (2007). Note that Compound B1 is an ultraviolet light - absorbing dye, and Compounds B2 - B4 are near - infrared light - absorbing dyes.

[0114]

Chemical formula

[0115] <Calculation of Hansen solubility parameters (HSP) of SiO2 microparticles> The HSP (dispersion term δd, polarization term δp, hydrogen - bonding term δh) of the SiO2 microparticles used in the test was calculated by inputting the dissolution test into the HSP calculation software (HSPiP 5th Edition version 5.3.04). First, 30 mg of each SiO2 microparticle was added to 1.2 ml of 21 kinds of solvents with known HSP shown in the following table. The solution with the added sample was shaken at 40 kHz for 5 minutes using an ultrasonic cleaner MCS - 2 (manufactured by AS ONE Corporation). Samples where all the particles dissolved within 1 hour after ultrasonic cleaning were judged as ○, and those where the particles did not dissolve were judged as ×. The results are shown in the following table. Next, the solubility results in various solvents were input using HSPiP to obtain the HSP of each SiO2 microparticle.

[0116]

Table 2

[0117] <Calculation of Hansen solubility parameters (HSP) of pigments (Pigments B1, B2)> The HSP was calculated by inputting the structural formula of each compound in the SMILES format into the HSP calculation software (HSPiP 5th Edition version 5.3.04).

[0118] <Calculation of Hansen solubility parameters (HSP) of pigments (Pigments B3, B4)> The HSP (dispersion term δd, polarization term δp, hydrogen bonding term δh) of the pigments used in the test was calculated by inputting the dissolution test into the HSP calculation software (HSPiP 5th Edition version 5.3.04). First, 5 mg of each pigment was added to 140 μl of 20 - 29 types of solvents with known HSP shown in Table 3 or Table 4 below. After stirring about 30 times by hand, those in which all the pigments dissolved within 1 hour were judged as ○, and those in which the pigments did not dissolve were judged as ×. The results are shown in the table below. Next, the solubility results in various solvents were input using HSPiP to determine the HSP of each pigment.

[0119]

Table 3

[0120]

Table 4

[0121] <Calculation of the absolute value of the difference from the Hansen solubility parameter (Ra IR ) The absolute value of the difference Ra IR between the HSP of the SiO2 fine particles and the HSP of the pigment was determined from the following formula. Ra IR =[4×(δd p -δd d ) 2 +(δpp -δp d ) 2 +(δh p -δh d ) 2 1 / 2 (where δd p 、δp p 、δh p represent the dispersion term, polarization term, and hydrogen bonding term of the HSP of SiO2 microparticles respectively, and δd d 、δp d 、δh d represent the dispersion term, polarization term, and hydrogen bonding term of the HSP of the dye respectively.)

[0122] The HSP of SiO2 microparticles obtained above, the HSP of the dye, and the absolute value Ra IR of the difference between the HSP of SiO2 microparticles and the HSP of the dye are shown in Tables 5 to 7 below respectively.

[0123]

Table 5

[0124]

Table 6

[0125]

Table 7

[0126] <Resin> As the resin of the absorption layer, a polyimide resin or an epoxy resin was used. The polyimide resin used was C-3G30G manufactured by Mitsubishi Gas Chemical Company, Inc. The epoxy resin was synthesized by using the following epoxy compound (VG3101L manufactured by Printec Co., Ltd., molecular weight: 597.28) as a monomer and a thermal cationic generator (SI-B3 manufactured by Sanshin Chemical Industry Co., Ltd.) as a polymerization initiator for polymerization.

[0127]

Chemical formula

[0128] <Characteristics of the absorption layer> [Examples 1-1, 1-6] The dyes listed in Table 8 or Table 9 were mixed with C-3G30G (Mitsubishi Gas Chemical Co., Ltd., polyimide varnish) diluted with an organic solvent, and the polyimide solution and dyes were thoroughly dissolved. The resulting resin solution was coated onto a glass substrate (alkali glass, Matsunami Glass Co., Ltd., D263) using a spin coater, and the organic solvent was removed by heating to obtain an absorption layer with a thickness of 1 μm.

[0129] [Examples 1-2, 1-7] A dye solution was prepared by mixing an epoxy compound with the amounts of dye and initiator listed in Table 8 or Table 9. The obtained dye solution was applied to a glass substrate (alkali glass, D263 manufactured by Matsunami Glass Co., Ltd.), and the resin composition was heat-cured by sequentially heating at 80°C for 5 minutes and then at 160°C for 1 hour to obtain an absorption layer with a thickness of 1 μm.

[0130] [Examples 1-3 to 1-5, 1-8 to 1-11] A dye solution was prepared by mixing an epoxy compound with the amounts of dye, initiator, and SiO2 fine particles listed in Table 8 or Table 9. The obtained dye solution was applied to a glass substrate (alkali glass, D263 manufactured by Matsunami Glass Co., Ltd.), and the resin composition was heat-cured by sequentially heating at 80°C for 5 minutes and then at 160°C for 1 hour to obtain an absorption layer with a thickness of 1 μm.

[0131] <Spectral properties of the absorption layer> The obtained absorption layer was measured using a UV-Vis spectrophotometer (Hitachi High-Technologies Corporation, UH-4150 model) in the wavelength range of 350 nm to 1200 nm, with transmission spectroscopy at 0 degrees of incidence and reflection spectroscopy at 5 degrees of incidence. The transmittance is expressed as the internal transmittance using the following formula. Internal transmittance = [Measured transmittance (incident angle 0 degrees) / (100 - reflectance (incident angle 5 degrees))] × 100

[0132] <Haze in the absorption layer> For the obtained absorption layer, measurement was carried out using a haze meter NDH7000SPII (manufactured by Nippon Denshoku Industries Co., Ltd.) with a D265 light source as the light source.

[0133] Each characteristic is shown in Tables 8 and 9 below. Note that Examples 1-1 to 1-11 are reference examples.

[0134]

Table 8

[0135]

Table 9

[0136] <Characteristics of the absorption layer> 〔Examples 2-1 to 2-4〕 The materials described in Table 10 were mixed and stirred at 50°C for 30 minutes or more to prepare Formulation Liquids Type A to Type D. The content unit of each material is mass%.

[0137] (Example 2-1) Formulation Liquid Type A was spin-coated on an alkali glass substrate to form an absorption layer with a thickness of 1 μm.

[0138] (Examples 2-2 to 2-4) Formulation Liquid Type A was spin-coated on an alkali glass substrate to form an absorption layer (first layer) with a thickness of 1 μm. Subsequently, one of the Formulation Liquids Type B, Type C, or Type D was spin-coated on the above absorption layer (first layer), and the resin composition was thermally cured by sequentially heating at 80°C for 5 minutes and 160°C for 1 hour to form an absorption layer (second layer) with a thickness of 1 μm.

[0139] <Spectral characteristics of the absorption layer> The obtained absorption layer was measured using a UV-Vis spectrophotometer (Hitachi High-Technologies Corporation, UH-4150 model) in the wavelength range of 350 nm to 1200 nm, with transmission spectroscopy at 0 degrees of incidence and reflection spectroscopy at 5 degrees of incidence. The transmittance is expressed as the internal transmittance using the following formula. Internal transmittance = [Measured transmittance (incident angle 0 degrees) / (100 - reflectance (incident angle 5 degrees))] × 100

[0140] Each characteristic is shown in Table 10 below. Furthermore, the spectral transmittance curves of the absorption layers in Examples 2-2 and 2-4 are shown in Figure 3. Examples 2-1 to 2-4 are for reference only.

[0141] [Table 10]

[0142] <Optical filters> [Examples 3-1 to 3-3] The materials listed in Table 12 were mixed and stirred at 50°C for at least 30 minutes to prepare formulations Type A to Type D. The content of each material is expressed in mass percent. A reflective layer consisting of a dielectric multilayer film with the configuration of Type 1 shown in Table 11, designed to shield near-infrared light, was fabricated on an alkali glass substrate by vapor deposition to obtain a dielectric multilayer film-coated substrate. On the main surface of the obtained dielectric multilayer substrate that did not have the dielectric multilayer film laminated, the Type A formulation was spin-coated to form a 1 μm thick absorption layer (first layer). Next, one of the Type B, Type C, or Type D formulations was spin-coated onto the absorption layer (first layer), and the resin composition was heat-cured by sequentially heating at 80°C for 5 minutes and then at 160°C for 1 hour, thereby forming a 1 μm thick absorption layer (second layer). Next, an anti-reflective film made of SiO2 / TiO2 was deposited on the above-mentioned absorption layer (second layer). An optical filter was fabricated based on the above.

[0143] [Table 11]

[0144] <Spectral characteristics of optical filters> The obtained optical filters were subjected to transmission spectroscopy in the wavelength range of 350 nm to 1200 nm, at incident angles of 0 and 50 degrees, using a UV-Vis spectrophotometer (Hitachi High-Technologies Corporation, UH-4150 model).

[0145] <Haze in optical filters> The obtained optical filters were measured using a haze meter NDH7000SPII (manufactured by Nippon Denshoku Industries Co., Ltd.) and a D265 light source.

[0146] Each characteristic is shown in Table 12 below. Furthermore, the spectral transmittance curve of the optical filter in Example 3-2 is shown in Figure 4. The spectral transmittance curve of the optical filter in Example 3-3 is shown in Figure 5. The spectral transmittance curves of the optical filters in Example 3-1 and Example 3-3 are shown in Figure 6. Note that Example 3-1 is a comparative example, while Examples 3-2 to 3-3 are examples of actual cases.

[0147] [Table 12]

[0148] From the above results, it can be seen that the optical filters of Examples 3-2 and 3-3, which have an absorption layer containing SiO2 fine particles, exhibit excellent visible light transmittance and near-infrared light shielding, and show a steep change in transmittance in the 650 nm band. The optical filter in Example 3-1, which does not have an absorption layer containing SiO2 fine particles, has an average transmittance T 580-660(0deg)AVE The transmittance must be less than 60%, and the average transmittance must be T 430-580(0deg)AVE Since it is smaller than in Examples 3-2 and 3-3, the transmittance of visible light is low, and Δ(IR 10(0deg) -IR 75(0deg) Since the value exceeds 80 nm, it can be seen that the steepness of the transmittance change in the 650 nm band is small. [Explanation of Symbols]

[0149] 1…Optical filter, 10…Substrate, 11…Support, 1A,2A…Absorption layer, 31,32…Dielectric multilayer film

Claims

1. An optical filter comprising a substrate and a dielectric multilayer film, The substrate comprises an absorption layer (1) containing a near-infrared absorbing dye (1) and resin having a maximum absorption wavelength in the wavelength region of 690 to 740 nm, and an absorption layer (2) containing a near-infrared absorbing dye (2) and resin having a maximum absorption wavelength in the wavelength region of 740 nm to 870 nm. At least one of the absorption layer (1) and absorption layer (2) is made of SiO with an average primary particle size of 100 nm or less. ２ Contains fine particles, The optical filter is an optical filter that satisfies all of the following spectral characteristics (i-1) to (i-7). (i-1) Average transmittance T at an incident angle of 0 degrees in the range of 430 to 580 nm ４３０－５８０（０ｄｅｇ）ＡＶＥ over 85% (i-2) Average transmittance T at an incident angle of 0 degrees in the range of 580 to 660 nm ５８０－６６０（０ｄｅｇ）ＡＶＥ over 60% (i-3) Average transmittance T at an incident angle of 0 degrees in the range of 710-730 nm ７１０－７３０（０ｄｅｇ）ＡＶＥ less than 5% (i-4) Average transmittance T at an incident angle of 0 degrees in the range of 830 to 850 nm ８３０－８５０（０ｄｅｇ）ＡＶＥ less than 5% The wavelength IR at which the transmittance is 10% at an incident angle of 0 degrees in the range of 550 to 700 nm １０（０ｄｅｇ） and the wavelength IR at which the transmittance is 75% ７５（０ｄｅｇ） and the difference Δ(IR １０（０ｄｅｇ） −IR ７５（０ｄｅｇ） ) is 80 nm or less (i-6) Average transmittance T at an incident angle of 50 degrees in the range of 710-730 nm ７１０－７３０（５０ｄｅｇ）ＡＶＥ less than 5% (i-7) Average transmittance T at an incident angle of 50 degrees in the range of 830-850 nm ８３０－８５０（５０ｄｅｇ）ＡＶＥ less than 5%

2. The optical filter according to claim 1, wherein the substrate satisfies all of the following spectral characteristics (ii-1) to (ii-5). (ii-1) Average internal transmittance T at 430-580 nm ４３０－５８０ＡＶＥ over 80% (ii-2) Average internal transmittance T in the range of 580 to 660 nm ５８０－６６０ＡＶＥ over 87% (ii-3) Average internal transmittance T at 710-730 nm ７１０－７３０ＡＶＥ less than 20% (ii-4) Average internal transmittance T at 830-850 nm ８３０－８５０ＡＶＥ less than 30% (ii-5) Wavelength IR at which internal transmittance is 10% in the range of 550-700 nm １０ And the wavelength IR with an internal transmittance of 75% ７５ The difference Δ(IR) １０ -IR ７５ ) is 75 nm or less

3. The absorption layer (2) is SiO with an average primary particle size of 100 nm or less. ２ The optical filter according to claim 1, comprising fine particles.

4. The optical filter according to claim 1, wherein at least one of the resin in the absorption layer (1) and the resin in the absorption layer (2) is an epoxy resin.

5. The optical filter according to claim 1, wherein the haze is 1% or less.

6. The SiO in the absorbent layer (1) or the absorbent layer (2) ２ The optical filter according to claim 1, wherein the content of fine particles is 5% by mass or more.

7. The optical filter according to claim 1, wherein the near-infrared absorbing dye (2) includes a cyanine dye.

8. The optical filter according to claim 1, wherein the near-infrared absorbing dye (1) includes a squarylium dye.

9. The SiO calculated by the following formula (A) ２ The absolute value Ra of the difference between the Hansen solubility parameter of the fine particles and the Hansen solubility parameter of the near-infrared absorbing dye (2) ＩＲ The optical filter according to claim 1, wherein the value is 10 or less. Ra ＩＲ =[4×(δd ｐ -δd ｄ ) ２ +(δp ｐ -δp ｄ ) ２ +(δh ｐ -δh ｄ ) ２ ] １／２ (A) (The meaning of each symbol in the formula is as follows.) δd ｐ SiO ２ Dispersion term of the Hansen solubility parameter for fine particles δp ｐ SiO ２ Polarization term of Hansen solubility parameter for fine particles δh ｐ SiO ２ Hydrogen bonding term of Hansen solubility parameter for fine particles δd ｄ : Dispersion term of the Hansen solubility parameter for near-infrared absorbing dye (2) δp ｄ : Polarization term of Hansen solubility parameter for near-infrared absorbing dye (2) δh ｄ (Hansen solubility parameter of near-infrared absorbing dye (2) - hydrogen bonding term)

10. The optical filter according to claim 1, wherein the near-infrared absorbing dye (2) includes at least one of the cyanine dyes shown in the following formulas (III) to (V). 【Chemistry 1】 【Chemistry 2】 [The symbols in the above formula are as follows: R １０１ ~R １１１ and R １２１ ~R １３１ Each of these independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 15 carbon atoms (which may have substituents), or an aryl group having 5 to 20 carbon atoms. Y represents a halogen atom or an optionally substituted phenyl group. X － This indicates a monovalent anion. n1 and n2 are either 0 or 1. - (CH ２ ) ｎ１ A carbon ring containing -, and - (CH ２ ) ｎ２ The hydrogen atom bonded to the carbon ring containing - may be substituted with a halogen atom, a C1-C15 alkyl group which may have substituents, or a C5-C20 aryl group.

11. An imaging apparatus comprising an optical filter according to any one of claims 1 to 10.

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