Optical filter

Abstract

The present invention aims to provide an optical filter that has high transmittance of visible light, high shielding of near-infrared and ultraviolet light, and in particular, high transmittance of blue light and suppression of the decrease in shielding performance of ultraviolet light at high incidence angles. [Solution] The present invention relates to an optical filter comprising a substrate and a dielectric multilayer film laminated on at least one main surface side of the substrate, wherein the substrate has a resin film containing a dye (U) having a maximum absorption wavelength of 360 to 395 nm in dichloromethane, a dye (A) having a maximum absorption wavelength of 600 to 800 nm in dichloromethane, and a resin, and the optical filter satisfies specific spectral characteristics.

Description

[Technical Field]

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

[0002] In imaging devices using solid-state image sensors, optical filters are used that transmit visible light (hereinafter also referred to as "visible light") and block light in the ultraviolet wavelength region (hereinafter also referred to as "ultraviolet light" or "UV") and near-infrared wavelength region (hereinafter also referred to as "near-infrared light" or "NIR") in order to reproduce colors well and obtain sharp images.

[0003] Such optical filters can take various forms, such as reflective filters that alternately stack dielectric thin films with different refractive indices on one or both sides of a transparent substrate (dielectric multilayer film) and reflect the light to be blocked by utilizing light interference. However, optical filters with dielectric multilayer films have problems such as changes in the spectral transmittance curve depending on the angle of incidence, light loss where ultraviolet light that should have high reflectivity at high angles of incidence becomes highly transmittant, and noise caused by ultraviolet light reflected by the dielectric multilayer film. Using such filters may cause the spectral sensitivity of a solid-state image sensor to be affected by the angle of incidence. Therefore, there has been a need for an optical filter that blocks ultraviolet light independently of the angle of incidence without significantly affecting the transmittance of visible light.

[0004] In contrast, Patent Documents 1 to 4 describe optical filters that have low incident angle dependence for light with wavelengths of 370 to 425 nm, by combining an absorption layer containing UV-absorbing dyes and NIR-absorbing dyes in a transparent resin with a dielectric multilayer film, thereby possessing both UV-cutting and NIR-cutting capabilities. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-16649 [Patent Document 2] Japanese Patent No. 6504176 [Patent Document 3] Japanese Patent No. 6020740 [Patent Document 4] Japanese Patent No. 6256335 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, the optical filters described in Patent Documents 1 to 4 had room for improvement in terms of the transmittance of visible light, particularly blue light, and the shielding of ultraviolet light at high incident angles. Therefore, the present invention aims to provide an optical filter that has high transmittance of visible light, high shielding of near-infrared and ultraviolet light, and in particular high transmittance of blue light and suppression of the decrease in shielding performance of ultraviolet light at high incidence angles. [Means for solving the problem]

[0007] The present invention provides an optical filter having the following configuration. [1] An optical filter comprising a substrate and a dielectric multilayer film laminated on at least one main surface side of the substrate, The substrate has a resin film containing a dye (U) having a maximum absorption wavelength of 360 to 385 nm in dichloromethane, a dye (A) having a maximum absorption wavelength of 600 to 800 nm in dichloromethane, and a resin. The aforementioned dye (U) is a dye (U1) having a maximum absorption wavelength of 370-385 nm in dichloromethane. The resin film further contains a dye (U2) having a maximum absorption wavelength of 385-405 nm in dichloromethane. The optical filter is an optical filter that satisfies all of the following spectral characteristics (i-1) to (i-2) and (i-4). (i-1) Average transmittance T in the spectral transmittance curve for wavelengths of 440-480 nm 440-480 over 86% (i-2) At a wavelength of 350 to 450 nm and an incident angle of 0 degrees, the wavelength when the transmittance is 10% is defined as UV10 (0deg) , the wavelength when the transmittance is 20% is defined as UV20 (0deg) , the wavelength when the transmittance is 50% is defined as UV50 (0deg) ; and At a wavelength of 350 to 450 nm and an incident angle of 50 degrees, the wavelength when the transmittance is 10% is defined as UV10 (50deg) , the wavelength when the transmittance is 20% is defined as UV20 (50deg) , the wavelength when the transmittance is 50% is defined as UV50 (50deg) ; when UV10 (0deg) and UV10 (50deg) , the absolute value of the difference therebetween is 3 nm or less; UV20 (0deg) and UV20 (50deg) , the absolute value of the difference therebetween is 4 nm or less; UV50 (0deg) and UV50 (50deg) , the absolute value of the difference therebetween is 4 nm or less (i-4) The average transmittance T in the spectral transmittance curve at a wavelength of 370 to 400 nm and an incident angle of 0 degrees 370-400(0deg) is 1% or less

Advantages of the Invention

[0008] According to the present invention, an optical filter having high visible light transmittance, high near-infrared and ultraviolet light shielding properties, particularly high blue light transmittance, and suppression of a decrease in ultraviolet light shielding property at a high incident angle 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 cross-sectional view schematically showing another example of an optical filter according to an embodiment. [Figure 4] FIG. 4 is a cross-sectional view schematically showing another example of an optical filter according to an embodiment. [Figure 5] Figure 5 shows the spectral transmittance curve of the optical filter in Example 2-14. [Figure 6] Figure 6 shows the spectral transmittance curve of the optical filter in Example 2-15. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below. In this specification, near-infrared absorbing dyes may be abbreviated as "NIR dyes," and ultraviolet absorbing dyes may be abbreviated as "UV dyes." In this specification, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas. A dye consisting of compound (I) is also referred to as dye (I), and the same applies to other dyes. Furthermore, the group represented by formula (I) is also referred to as group (I), and the same applies to groups represented by other formulas.

[0011] In this specification, internal transmittance is defined as the transmittance obtained by subtracting the effect of interfacial reflection from the measured transmittance, as shown by the formula: measured transmittance / (100 - reflectance). In this specification, the spectral transmission of a substrate and the transmission of a resin film, including cases where the dye is contained in the resin, are all referred to as "internal transmission" even when the term "transmission" is used. On the other hand, the transmission measured by dissolving the dye in a solvent such as dichloromethane, and the transmission of an optical filter having a dielectric multilayer film, are measured transmissions.

[0012] In this specification, for a particular wavelength range, a transmittance of, for example, 90% or more means that the transmittance does not fall below 90% across the entire wavelength range, i.e., the minimum transmittance in that wavelength range is 90% or more. Similarly, for a particular wavelength range, a transmittance of, for example, 1% or less means that the transmittance does not exceed 1% across the entire wavelength range, i.e., the maximum transmittance in that wavelength range is 1% or less. The same applies to internal transmittance. The average transmittance and average internal transmittance in a particular wavelength range are the arithmetic mean of the transmittance and internal transmittance for every 1 nm in that wavelength range. In this specification, the symbol "~" used to indicate a numerical range includes both upper and lower limits.

[0013] <Optical filters> An optical filter according to one embodiment of the present invention (hereinafter also referred to as "this filter") comprises a substrate and a dielectric multilayer film laminated as the outermost layer on at least one main surface side of the substrate, and is an optical filter that satisfies specific spectral characteristics described later. Here, the substrate has a resin film containing a dye (U) having a maximum absorption wavelength of 360 to 395 nm in dichloromethane, a dye (A) having a maximum absorption wavelength of 600 to 800 nm in dichloromethane, and a resin.

[0014] An example of the configuration of this filter will be explained using the drawings. Figures 1 to 4 are schematic cross-sectional views showing an example of an optical filter according to one embodiment. The optical filter 1A shown in Figure 1 is an example in which a dielectric multilayer film 30 is provided on one main surface side of the substrate 10. Note that "having a specific layer on the main surface side of the substrate" is not limited to cases where the layer is in contact with the main surface of the substrate, but also includes cases where another functional layer is provided between the substrate and the layer.

[0015] The optical filter 1B shown in Figure 2 is an example in which a dielectric multilayer film 30 is present on both main surfaces of the substrate 10.

[0016] The optical filter 1C shown in Figure 3 is an example in which the substrate 10 has a support 11 and a resin film 12 laminated on one main surface side of the support 11. The optical filter 1C further has dielectric multilayer films 30 on top of the resin film 12 and on the main surface side of the support 11 where the resin film 12 is not laminated.

[0017] The optical filter 1D shown in Figure 4 is an example in which the substrate 10 has a support 11 and a resin film 12 laminated on both main surfaces of the support 11. The optical filter 1D further has a dielectric multilayer film 30 on each of the resin films 12.

[0018] The substrate in the optical filter of the present invention comprises a dye (U) having a maximum absorption wavelength of 360 to 395 nm in dichloromethane, a dye (A) having a maximum absorption wavelength of 600 to 800 nm in dichloromethane, and a resin. Dye (U) is a UV dye, and dye (A) is an NIR dye. By containing dyes that absorb ultraviolet and near-infrared light in the substrate, the deterioration of the spectral characteristics of the dielectric multilayer film at high incidence angles, such as light loss and noise in the ultraviolet and near-infrared regions, can be suppressed by the absorption characteristics of the substrate. Each dye and resin will be described later.

[0019] The optical filter of the present invention satisfies all of the following spectral characteristics (i-1) to (i-5). (i-1) Average transmittance T in the spectral transmittance curve for wavelengths of 440-480 nm 440-480 over 86% (i-2) The wavelength at which the transmittance is 10% at wavelengths of 350-450 nm and an incident angle of 0 degrees is UV10 (0deg) The wavelength when the transmittance is 20% is UV20 (0deg) The wavelength when the transmittance is 50% is UV50 (0deg year, UV10 is defined as the wavelength at which the transmittance is 10% at wavelengths of 350-450 nm and an incident angle of 50 degrees. (50deg) The wavelength when the transmittance is 20% is UV20 (50deg) The wavelength when the transmittance is 50% is UV50 (50deg) In that case, UV10 (0deg) and UV10 (50deg) The absolute value of the difference is 3 nm or less. UV20 (0deg) and UV20 (50deg) The absolute value of the difference is 4 nm or less. UV50 (0deg) and UV50 (50deg) The absolute value of the difference is 4 nm or less. (i-3) Average transmittance T in the spectral transmittance curve for wavelengths of 400-440 nm 400-440 over 40% (i-4) Average transmittance T in the spectral transmittance curve at wavelengths of 370-400 nm and an incident angle of 0 degrees 370-400(0deg) less than 1% (i-5) Average transmittance T in the spectral transmittance curve at wavelengths of 370-400 nm and an incident angle of 50 degrees 370-400(50deg) less than 0.5%

[0020] This filter, which satisfies all of the spectral characteristics (i-1) to (i-5), is an optical filter that maintains good transmittance of visible light, especially blue light, while suppressing the decrease in ultraviolet light shielding performance, particularly at high incidence angles.

[0021] Satisfying spectral characteristic (i-1) means that it has excellent transmittance in the visible light range. T of spectral characteristic (i-1) 440-480 The percentage is preferably 87% or more, and more preferably 89% or more.

[0022] By satisfying spectral characteristics (i-2), it means that there is little shift even at high incident angles around the UV absorption onset band of 350-450 nm, resulting in excellent color reproduction. In spectral characteristics (i-2), UV10 (0deg) and UV10 (50deg) The absolute value of the difference is preferably 2.5 nm or less, UV20 (0deg) and UV20 (50deg) The absolute value of the difference is preferably 3 nm or less, UV50 (0deg) and UV50 (50deg) The absolute value of the difference is preferably 3 nm or less.

[0023] The satisfying of spectral characteristics (i-3) means that the material exhibits excellent transmittance of blue light before the UV absorption onset band at wavelengths of 400-440 nm. 400-440 This is preferably 45% or more, and more preferably 50% or more.

[0024] Satisfying spectral characteristics (i-4) means that the light-shielding properties are high in the UV absorption band at wavelengths of 370-400 nm. 370-400(0deg) teeth, Preferably, it is 0.5% or less.

[0025] By satisfying the spectral characteristic (i-5), it means that in the UV absorption band with a wavelength of 370 to 400 nm, light leakage is less likely to occur even at a high incident angle, and the light shielding property is high. The T of the spectral characteristic (i-5) 370-400(50deg) is preferably 0.1% or less.

[0026] The optical filter of the present invention preferably further satisfies the following spectral characteristic (i-6). (i-6) At a wavelength of 350 to 450 nm and an incident angle of 0 degrees, when the transmittance is 10%, the wavelength is UV10 (0deg) , and when the transmittance is 70%, the wavelength is UV70 (0deg) When defined as such, the absolute value of the difference between UV10 (0deg) and UV70 (0deg) is 16 nm or less

[0027] By satisfying the spectral characteristic (i-6), it means that in the UV absorption start band with a wavelength of 350 to 450 nm, the slope of the spectral transmittance curve is steep. The absolute value in the spectral characteristic (i-6) is more preferably 14 nm or less, and particularly preferably 13 nm or less.

[0028] Hereinafter, the substrate and the dielectric multilayer film will be described. This filter is designed to satisfy the above spectral characteristics (i-1) to (i-5) by, for example, giving the substrate the ability to absorb ultraviolet light and near-infrared light, and by the absorption characteristics of the substrate and the reflection characteristics of the dielectric multilayer film.

[0029] <Substrate> In the optical filter of the present invention, the substrate has a resin film containing a dye (U), a dye (A) described later, and a resin.

[0030] <UV Dye> The dye (U) is a UV dye having a maximum absorption wavelength of 360 to 395 nm in dichloromethane. By containing such a dye, ultraviolet light can be effectively cut.

[0031] The dye (U) preferably has specific spectral properties in the resin. Specifically, it is preferable that the spectral transmittance curve of a coating film obtained by dissolving the dye (U) in a resin and coating it onto an alkali glass plate satisfies all of the following spectral properties (ii-1) to (ii-6). It is preferable that the resin is the same as the resin contained in the substrate.

[0032] (ii-1) Average transmittance T at wavelengths of 400-440 nm 400-440 over 40% (ii-2) Average transmittance T at wavelengths of 370-400 nm 370-400 less than 5% (ii-3) Transmittance T at a wavelength of 400 nm 400 less than 7% (ii-4) Transmittance T at a wavelength of 390 nm 390 less than 5% (ii-5) Transmittance T at a wavelength of 380 nm 380 less than 5% (ii-6) Transmittance T at a wavelength of 370 nm 370 less than 5%

[0033] Satisfying optical property (ii-1) means that the material exhibits excellent transmittance of blue light before the UV absorption onset band at wavelengths of 400-440 nm. 400-440 It is more preferably 45% or more, and particularly preferably 50% or more.

[0034] Satisfying optical property (ii-2) means that the light-shielding performance is high in the UV absorption band with wavelengths of 370-400 nm. 370-400 It is more preferably 3% or less, and particularly preferably 2% or less.

[0035] By satisfying optical property (ii-3), the transmittance at 400 nm, the UV absorption onset wavelength, is low, meaning that the light shielding performance is high at shorter wavelengths. Transmittance T of optical property (ii-3) 400 It is more preferably 5% or less, and particularly preferably 2% or less.

[0036] By satisfying optical properties (ii-4) to (ii-6), it means that light shielding can be ensured through absorption in the 370-390 nm wavelength band, where dielectric multilayer films are prone to light leakage due to their inability to completely block light at high incident angles. T of optical properties (ii-4) 390 It is more preferably 3% or less, and particularly preferably 1% or less. T of optical properties (ii-5) 380 It is more preferably 3% or less, and particularly preferably 1% or less. T of optical properties (ii-6) 370 It is more preferably 3% or less, and particularly preferably 1% or less.

[0037] The dye (U) preferably further satisfies the following spectral characteristics (ii-7) in the spectral transmittance curve of the above-mentioned coating film. (ii-7) Average internal transmittance T at wavelengths of 440-480 nm 440-480 A T of 79% or more satisfies optical properties (ii-7), meaning that the absorption of the dye itself does not cause a loss of transmittance in the visible light range. 440-480 It is more preferably 80% or more, and particularly preferably 81% or more.

[0038] Furthermore, the dye (U) is preferably one that satisfies the following spectral characteristics (iii-1). (iii-1) In a spectral transmittance curve measured by dissolving the dye (U) in dichloromethane so that the transmittance at the maximum absorption wavelength is 10%, when the wavelength at which the transmittance is 10% in the 350-450 nm range is defined as UV10 and the wavelength at which the transmittance is 70% is defined as UV70, the absolute value of the difference between UV10 and UV70 is 25 nm or less. Satisfying spectral characteristic (iii-1) means that the slope of the spectral transmission curve is steep in the UV absorption onset band at wavelengths of 350-450 nm. This allows for the transmission of more of the necessary blue light and efficient blocking of the ultraviolet light region that needs to be shielded. The absolute value in the spectral characteristics (iii-1) is more preferably 22 nm or less.

[0039] The dye (U) may be used alone on the substrate, or two or more may be used in combination. However, from the viewpoint of more efficiently blocking ultraviolet light with a small amount, it is preferable to use two or more dyes with different maximum absorption wavelengths in combination. Furthermore, when using two or more dyes in combination, the individual compounds do not necessarily need to have the properties of dye (U); it is sufficient for the mixture to have the properties of dye (U).

[0040] As the dye (U), a dye (U1) having a maximum absorption wavelength of 370 to 385 nm in dichloromethane is more preferred. Furthermore, if the substrate contains dye (U1), it is preferable to further contain a dye (U2) having a maximum absorption wavelength of 385 to 405 nm in dichloromethane. It is preferable that the maximum absorption wavelengths of dye (U1) and dye (U2) in the resin are different, and the absolute value of the difference in the maximum absorption wavelengths in the resin is preferably 10 nm or more and 15 nm or less, more preferably 10 nm or more and 14 nm or less. By using UV dyes with different maximum absorption wavelengths in combination, ultraviolet light can be blocked more efficiently with a smaller amount of dye.

[0041] Examples of pigments (U) include oxazole pigments, merocyanine pigments, cyanine pigments, naphthalimide pigments, oxadiazole pigments, oxazine pigments, oxazolidine pigments, naphthalic acid pigments, styryl pigments, anthracene pigments, cyclic carbonyl pigments, and triazole pigments. Among these, oxazole pigments and merocyanine pigments are preferred, and merocyanine pigments are more preferred.

[0042] Furthermore, from the viewpoint of obtaining an optical filter with excellent light resistance, it is particularly preferable to use two or more merocyanine dyes with different maximum absorption wavelengths in combination. NIR dye (A) is prone to degradation when used in combination with UV dyes, but this can be prevented by using two or more merocyanine dyes as UV dyes.

[0043] As the pigment (U), merocyanine pigments represented by the following formula (M) are particularly preferred.

[0044] [ka]

[0045] The symbols in equation (M) are as follows:

[0046] R 1 This represents a monovalent hydrocarbon group having 1 to 12 carbon atoms, which may have substituents. Preferred substituents are alkoxy groups, acyl groups, acyloxy groups, cyano groups, dialkylamino groups, or chlorine atoms. The number of carbon atoms in the alkoxy groups, acyl groups, acyloxy groups, and dialkylamino groups is preferably 1 to 6.

[0047] R without substituents 1 Specifically, preferred are C1-C12 alkyl groups in which some of the hydrogen atoms may be substituted with an aliphatic ring, an aromatic ring, or an alkenyl group, C3-C8 cycloalkyl groups in which some of the hydrogen atoms may be substituted with an aromatic ring, an alkyl group, or an alkenyl group, and C6-C12 aryl groups in which some of the hydrogen atoms may be substituted with an aliphatic ring, an alkyl group, or an alkenyl group.

[0048] R 1 If the alkyl group is an unsubstituted alkyl group, it may be linear or branched, and its carbon number is more preferably 1 to 6.

[0049] R 1When the alkyl group has 1 to 12 carbon atoms, in which some of the hydrogen atoms are substituted with an aliphatic ring, an aromatic ring, or an alkenyl group, alkyl groups with 1 to 4 carbon atoms having a cycloalkyl group with 3 to 6 carbon atoms, alkyl groups with 1 to 4 carbon atoms substituted with a phenyl group are more preferred, and alkyl groups with 1 or 2 carbon atoms substituted with a phenyl group are particularly preferred. Note that an alkyl group substituted with an alkenyl group means an alkenyl group as a whole, but without an unsaturated bond between the 1st and 2nd positions, such as an allyl group or a 3-butenyl group.

[0050] Preferred R 1 Q is a C1-C6 alkyl group in which some of the hydrogen atoms may be substituted with cycloalkyl groups or phenyl groups. Particularly preferred Q 1 This refers to an alkyl group having 1 to 6 carbon atoms, specifically including methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and t-butyl groups.

[0051] R 2 ~R 5 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. The alkyl group and alkoxy group preferably have 1 to 6 carbon atoms, and more preferably 1 to 4 carbon atoms.

[0052] R 2 and R 3 Preferably, at least one of them is an alkyl group, and more preferably, both are alkyl groups. 2 and R 3 If it is not an alkyl group, a hydrogen atom is more preferable. 2 and R 3 Alkyl alkyl groups having 1 to 6 carbon atoms are particularly preferred.

[0053] R 4 and R 5 At least one of them is preferably a hydrogen atom, and both are more preferably hydrogen atoms. 4 or R 5 If it is not a hydrogen atom, an alkyl group having 1 to 6 carbon atoms is preferred.

[0054] Y represents a methylene group or an oxygen atom substituted with R 6 and R 7 represents. R 6 and R 7 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.

[0055] X represents any of the divalent groups represented by the following formulas (X1) to (X5).

[0056]

Chemical formula

[0057] R 8 and R 9 each independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, and R 10 to R 19 each independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent. R 8 to R 19 Examples of the substituents of 1 are the same as the substituents in R 8 to R 19 and the preferred embodiments are also the same. When R 1 to R 19 is a hydrocarbon group having no substituent, the same embodiments as those of unsubstituted R 1 are exemplified.

[0058] In formula (X1), R 8 and R 9 may be different groups, but the same group is preferred. When R 8 and R 9 are unsubstituted alkyl groups, they may be linear or branched, and more preferably have 1 to 6 carbon atoms.

[0059] Preferred R 8 and R 9is an alkyl group having 1 to 6 carbon atoms, in which part of the hydrogen atoms may be substituted with a cycloalkyl group or a phenyl group. Particularly preferred R 8 and R 9 are both alkyl groups having 1 to 6 carbon atoms. Specifically, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, etc. can be mentioned.

[0060] In formula (X2), R 10 and R 11 are both more preferably alkyl groups having 1 to 6 carbon atoms, and it is particularly preferred that they are the same alkyl group.

[0061] In formula (X3), R 12 and R 15 are both preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms without a substituent. R 13 and R 14 which are two groups bonded to the same carbon atom, are both preferably a hydrogen atom or both are alkyl groups having 1 to 6 carbon atoms.

[0062] For the two groups R 16 and R 17 and R 18 and R 19 which are bonded to the same carbon atom in formula (X4), are both preferably a hydrogen atom or both are alkyl groups having 1 to 6 carbon atoms.

[0063] As the compound represented by formula (M), a compound in which Y is an oxygen atom and X is a group (X1), a group (X2) or a group (X5), and a compound in which Y is an unsubstituted methylene group and X is a group (X1), a group (X2) or a group (X5) are preferred.

[0064] Specific examples of the compound (M) that can be used as the dye (U) include the compounds shown in the following table.

[0065]

Table 1

[0066] [Table 2]

[0067] Specific examples of compounds (M) that can be used as dyes (U1) are listed in the table below.

[0068] [Table 3]

[0069] Specific examples of compounds (M) that can be used as dyes (U2) include the compounds shown in the table below.

[0070] [Table 4]

[0071] Among these, compounds (1-1-2), (M-1-10), (M-1-24), and (M-1-28) are preferred as compound (M) due to their solubility in resins and solvents, visible light transmission, and especially their ability to satisfy optical properties (iii-1). Furthermore, when using two compounds (M) with different maximum absorption wavelengths in combination, the combinations of compound (M-1-28) and compound (M-1-2), compound (M-1-28) and compound (M-1-10), compound (M-1-24) and compound (M-1-2), and compound (M-1-24) and compound (M-1-10) are preferred, respectively. Compound (M) can be produced by known methods.

[0072] The content of the UV dye (U) in the resin film is preferably such that the product of the total content of the dyes (U) and (A) and the thickness of the resin film is 100 (mass%·μm) or less, more preferably 80 (mass%·μm) or less, still more preferably 70 (mass%·μm) or less, and particularly preferably 50 (mass%·μm) or less. When the addition amount of the UV dye increases, it causes a decrease in resin properties, and as a result, the adhesion to the dielectric multilayer film decreases. Also, the glass transition temperature of the resin drops, raising concerns about heat resistance. If the product of the total content of the dyes and the thickness of the resin film is within the above range, such problems can be prevented. Further, from the viewpoint of satisfying the desired spectral characteristics, the product of the content and the thickness is preferably 10 (mass%·μm) or more, more preferably 15 (mass%·μm) or more.

[0073] From the viewpoint of satisfying the above range, the content of the UV dye (U) in the resin film is preferably 5 to 25 parts by mass, more preferably 5 to 20 parts by mass, per 100 parts by mass of the resin. Within such a range, the above problems can be avoided without degrading the resin properties.

[0074] <NIR dye> In the optical filter of the present invention, the substrate contains the above dye (U) and the dye (A). The dye (A) is a NIR dye having a maximum absorption wavelength at 600 to 800 nm in dichloromethane. By containing such a dye, infrared light can be effectively cut.

[0075] As the dye (A), at least one selected from the group consisting of squarylium dyes, cyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, dithiol metal complex dyes, azo dyes, polymethine dyes, phthalide dyes, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, pyrylium dyes, thiopyrylium dyes, croconium dyes, tetraaldehyde ocolin dyes, triphenylmethane dyes, aminium dyes, and diimonium dyes is preferable.

[0076] The dye (A) preferably contains at least one dye selected from squarylium dye, phthalocyanine dye, and cyanine dye. Among these NIR dyes, squarylium dye and cyanine dye are preferred from a spectroscopic viewpoint, and phthalocyanine dye is preferred from a durability viewpoint.

[0077] As the squarylium dye, the compound shown in the following formula (I) is preferred.

[0078] [ka]

[0079] However, the symbols in equation (I) are as follows: R 24 and R 26 Each of these independently consists of a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl or alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 10 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 includes a hydrogen atom, a C1-C20 alkyl group or C6-C11 aryl group which may have substituents, or a C7-C18 aryl group which may have substituents and may have oxygen atoms between carbon atoms), -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.

[0080] [ka]

[0081] 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.

[0082] 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.

[0083] 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 2 Each of these is a group represented by one of the following formulas (1y) to (5y). 1 and X 2 However, in the case of the base represented by the following formula (2x), Y 1 and Y 2 Each of these may be a single bond, in which case there may be an oxygen atom between the carbon atoms.

[0084] [ka]

[0085] In formula (1x), the four Zs are each independently a hydrogen atom, a hydroxyl group, an alkyl or alkoxy group having 1 to 6 carbon atoms, or -NR 38 R 39 (R 38 and R 39 Each of these independently represents either a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. 31 ~R 36 Each independently comprises a hydrogen atom, a C1-C6 alkyl group, or a C6-C10 aryl group, R 37 This represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms.

[0086] R 27 , R 28 , R 29 , R 31 ~R 37 , R when it does not form a heteroalgebra 21 ~R 23 , and R 25 These may bond with any of the others to form a five-membered ring or a six-membered ring. 31 and R 36 , R 31 and R 37 They may be directly joined.

[0087] When R does not form a heteroalgebra, 21 and R 22 Each of these independently represents a hydrogen atom, an alkyl or allyl group having 1 to 6 carbon atoms which may have substituents, or an aryl or alaryl group having 6 to 11 carbon atoms which may have substituents. When a heterocycle is not formed, R 23 and R 25 Each of these independently represents a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 6 carbon atoms.

[0088] As for compound (I), for example, a compound represented by formula (I-1) is preferred from the viewpoint of being able to increase the visible light transmittance.

[0089] [ka]

[0090] The symbols in formula (I-1) are the same as those specified for the same symbols in formula (I), and the preferred embodiments are also the same.

[0091] 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).

[0092] -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)

[0093] 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 formula (4-2) is independently more preferred.

[0094] [ka]

[0095] 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.

[0096] In compound (I-1), R 24 From the perspective of increasing the transmittance of visible light, especially light with wavelengths of 430-550nm, -NH-SO2-R 30 It is preferable. In compound (I-1), R 24 ga-NH-SO2-R 30 The compound is shown in formula (I-12).

[0097] [ka]

[0098] R in compound (I-12) 23 and R 26 These are preferably, independently, 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, with a hydrogen atom being more preferred in any case.

[0099] In compound (I-12), R 30 From the viewpoint of light resistance, preferably, independently, are C1-C12 alkyl groups which may be branched, C1-C12 alkoxy groups which may be branched, or C6-C16 hydrocarbon groups which have an unsaturated ring structure. Examples of unsaturated ring structures include benzene, toluene, xylene, furan, benzofuran, etc. 30 Independently, a C1-C12 alkyl group that may be branched or a C1-C12 alkoxy group that may be branched is more preferable. 30 In each of the groups exhibiting this characteristic, some or all of the hydrogen atoms may be substituted with halogen atoms, particularly fluorine atoms.

[0100] Compound (I) can be produced by known methods, for example, U.S. Patent No. 5,543,086, U.S. Patent Application Publication No. 2014 / 0061505, and International Publication No. 2014 / 088063.

[0101] Examples of phthalocyanine dyes include the phthalocyanine dyes described in Japanese Patent No. 5884953 and International Publication No. 2019 / 168090.

[0102] As the cyanine dye, compounds represented by the following formula (A1) or formula (A2) are preferred.

[0103] [ka]

[0104] However, the symbols in formulas (A1) and (A2) are as follows: R 101 ~R 109 and R 121 ~R 131 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl or alkoxy group having 1 to 15 carbon atoms which may have substituents, or an aryl group having 5 to 20 carbon atoms. 110 ~ 114 and R 132 ~ 136 Each of these independently represents a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 15 carbon atoms. X - This indicates a monovalent anion. n1 and n2 are independently either 0 or 1. -(CH2) n1 -Carbon rings containing -(CH2) 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.

[0105] In equations (A1) and (A2), R102 ~R 105 , R 108 , R 109 , 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.

[0106] In equations (A1) and (A2), R 110 ~R 114 and R 132 ~R 136 Each of these is preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, with hydrogen atoms being more preferred from the viewpoint of obtaining high visible light transmittance.

[0107] 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.

[0108] R 101 and R 121 The C1-C15 alkyl group or the C5-C20 aryl group is preferred, and a branched C1-C15 alkyl group is more preferred from the viewpoint of maintaining high visible light transmittance in the transparent resin, similar to that in solution.

[0109] X - As for, I - BF4 - PF6 - ClO4 - Examples include anions represented by formula (X1) or (X2), preferably BF4- , or PF6 - That is the case.

[0110] [ka]

[0111] In the following explanation, R in pigment (A1) 101 ~R 114 The part excluding this is also called the skeleton (A1). The same applies to other pigments.

[0112] In formula (A1), compounds with n1 = 1 are shown in formula (A11), and compounds with n1 = 0 are shown in formula (A11). (A12) is shown.

[0113] [ka]

[0114] In equations (A11) and (A12), R 101 ~R 114 and X - This is the same as in the case of equation (A1). R 115 ~R 120 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl or alkoxy group having 1 to 15 carbon atoms which may have substituents, or an aryl group having 5 to 20 carbon atoms. 115 ~R 120 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. 115 ~R 120 It is preferable that they are the same group.

[0115] In equation (A2), compounds with n2 = 1 are shown in equation (A21), and compounds with n2 = 0 are shown in equation (A21). (A22) is shown.

[0116] [ka]

[0117] In equations (A21) and (A22), R 121 ~R 136 and X - This is the same as in the case of equation (A2). 137 ~R 142 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl or alkoxy group having 1 to 15 carbon atoms which may have substituents, or an aryl group having 5 to 20 carbon atoms. 137 ~R 142 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. 137 ~R 142 It is preferable that they are the same group.

[0118] Furthermore, pigments (A1) and (A2) can be produced by known methods described, for example, in Dyes and pigments 73 (2007) 344-352 and J. Heterocyclic chem, 42, 959 (2005).

[0119] As described above, the content of NIR dye (A) in the substrate is preferably such that the product of the total content of dye (U) and dye (A) and the thickness of the resin film is within a specific range. From the viewpoint of satisfying the above range, the content of NIR dye (A) in the resin film is preferably 5 to 25 parts by mass, more preferably 5 to 20 parts by mass, per 100 parts by mass of resin.

[0120] <Base material composition> The substrate in this filter may have a single-layer or multi-layer structure. Furthermore, the material of the substrate is not particularly limited; it may be an organic or inorganic material as long as it is a transparent material that transmits visible light in the 400-700 nm range. When the substrate has a single-layer structure, it is preferable that the resin substrate consists of a resin and a resin film containing a UV dye (U) and an NIR dye (A). When the substrate has a multilayer structure, it is preferable that a resin film containing a UV dye (U) and an NIR dye (A) is laminated on at least one main surface of the support. In this case, it is preferable that the support is made of a transparent resin or a transparent inorganic material.

[0121] As the resin, transparent resins are preferred, and examples include polyester resin, acrylic resin, epoxy resin, ene-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, poly-p-phenylene resin, polyarylene ether phosphine oxide resin, polyamide resin, polyimide resin, polyamide-imide resin, polyolefin resin, cyclic olefin resin, polyurethane resin, and polystyrene resin. These resins may be used individually or in mixtures of two or more. Among these, polyimide resin is preferred because it has excellent visible light transmittance and a high glass transition temperature, which reduces thermal degradation of the dye.

[0122] Glass and crystalline materials are preferred as transparent inorganic materials. Examples of glass that can be used as a support include phthalate glass, phosphate glass, and other absorption-type glass containing copper ions (near-infrared absorbing glass), soda-lime glass, borosilicate glass, alkali-free glass, and quartz glass. Depending on the purpose, absorption glass is preferred, and from the viewpoint of absorbing infrared light, phosphate glass and boiling phosphate glass are preferred. When it is desired to capture a large amount of red light (600-700 nm), alkali glass, alkali-free glass, and quartz glass are preferred. Note that "phosphate glass" also includes silicate glass in which part of the glass skeleton is composed of SiO2.

[0123] As the glass, chemically strengthened glass may be used, obtained by ion exchange at a temperature below the glass transition temperature, in which alkali metal ions with small ionic radii (e.g., Li ions, Na ions) present on the main surface of the glass plate are replaced with alkali ions with larger ionic radii (e.g., Na ions or K ions for Li ions, and K ions for Na ions).

[0124] Examples of crystalline materials that can be used as supports include birefringent crystals such as quartz, lithium niobate, and sapphire.

[0125] As a support material, inorganic materials are preferred, particularly glass and sapphire, from the viewpoint of shape stability related to long-term reliability such as optical properties and mechanical properties, as well as handling during filter manufacturing.

[0126] The resin film can be formed by preparing a coating solution by dissolving or dispersing dye (U) and dye (A), resin or resin raw material components, and each component as needed in a solvent, coating this solution onto a support, drying it, and further curing it as needed. The support may be the support included in this filter, or it may be a releaseable support used only when forming the resin film. The solvent may be any dispersion medium or solvent that can stably disperse or dissolve the components.

[0127] Furthermore, the coating solution may contain a surfactant to improve voids caused by minute bubbles, indentations caused by the adhesion of foreign matter, and repulsion during the drying process. In addition, methods such as immersion coating, cast coating, or spin coating can be used for applying the coating solution. After applying the above coating solution to the support, a resin film is formed by drying. Furthermore, if the coating solution contains raw material components of a transparent resin, a curing treatment such as thermosetting or photocuring is performed.

[0128] Furthermore, the resin film can also be manufactured in film form by extrusion molding. When the substrate is a single-layer structure (resin substrate) consisting of a resin film containing pigment (U) and pigment (A), the resin film can be used as the substrate as is. When the substrate is a multi-layer structure (composite substrate) having a support and a resin film containing pigment (U) and pigment (A) laminated on at least one main surface of the support, the substrate can be manufactured by laminating this film onto the support and integrating it by heat pressing or the like.

[0129] The resin film may be present as one layer within the optical filter, or as two or more layers. If there are two or more layers, each layer may have the same or different configuration.

[0130] The thickness of the resin film is preferably 10 μm or less, and more preferably 5 μm or less. Furthermore, when the substrate is a single-layer structure (resin substrate) consisting of a resin film containing dye (U) and dye (A), the thickness of the resin film is preferably 10 μm or less, more preferably 5 μm or less. When the substrate is a multilayer structure (composite substrate) having a support and a resin film containing dye (U) and dye (A), the thickness of the resin film is 10 μm or less, more preferably 5 μm or less. When the resin film consists of multiple layers, the total thickness of each layer is preferably 20 μm or less, more preferably 10 μm or less.

[0131] The shape of the substrate is not particularly limited and may be in the form of a block, plate, or film. Furthermore, the thickness of the substrate is preferably 300 μm or less, more preferably 50 to 300 μm, and particularly preferably 70 to 300 μm, from the viewpoint of preventing warping deformation that occurs during reliability fluctuations when a dielectric multilayer film is formed, or from handling considerations. Furthermore, the thickness of the substrate is preferably 120 μm or less when the substrate is a resin substrate containing resin and dye, due to the advantage of lowering the height, and preferably 50 μm or more from the viewpoint of reducing warping during multilayer film formation. When the substrate is a composite substrate comprising a support and a resin film, the thickness is preferably 70 μm to 110 μm.

[0132] <Dielectric multilayer film> In this filter, the dielectric multilayer film is laminated as the outermost layer on at least one main surface side of the substrate.

[0133] 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.

[0134] The NIR reflective layer is a dielectric multilayer film designed to block near-infrared light. For example, the NIR reflective layer has wavelength selectivity, transmitting visible light and primarily reflecting near-infrared light outside the light-blocking region of the resin film. 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 be designed to further block light in wavelengths other than the near-infrared region, such as the near-ultraviolet region, as appropriate.

[0135] 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, and Nb2O5. Of these, TiO2 is preferred in terms of film formation properties, reproducibility in refractive index, stability, etc.

[0136] 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 These are some examples. SiO2 is preferred in terms of reproducibility, stability, and cost-effectiveness in film formation.

[0137] Furthermore, it is preferable that the transmittance of the NIR reflective layer changes abruptly in the boundary wavelength region between the transmittance and shielding regions. For this purpose, the total number of layers of dielectric multilayer films constituting the reflective layer is preferably 15 or more, more preferably 25 or more, and even more preferably 30 or more. 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 or less, more preferably 75 or less, and even more preferably 60 or less. In addition, the film thickness of the reflective layer is preferably 2 to 10 μm overall.

[0138] If the total number of layers and thickness of the dielectric multilayer film are within the above range, the NIR reflective layer can meet the miniaturization requirements and suppress incident angle dependence while maintaining high productivity. Furthermore, for the formation of the dielectric multilayer film, vacuum deposition processes such as CVD, sputtering, and vacuum evaporation, as well as wet deposition processes such as spraying and dipping, can be used.

[0139] The NIR reflective layer may provide predetermined optical properties 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 shields light in the short-wavelength band of the near-infrared region, and the other may be a near-infrared / near-ultraviolet reflective layer that shields light in both the long-wavelength band of the near-infrared region and the near-ultraviolet region.

[0140] 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 films, similar to the reflective layer.

[0141] This filter may include, as other components, for example, a component (layer) that provides absorption by inorganic fine particles or the like that control the transmission and absorption of light in a specific wavelength range. Specific examples of the inorganic fine particles include ITO (Indium Tin Oxides), ATO (Antimony-doped Tin Oxides), cesium tungstate, lanthanum boride, and the like. ITO fine particles and cesium tungstate fine particles have a high visible light transmittance and light absorption properties in a wide range of infrared wavelength regions exceeding 1200 nm, and thus can be used when such infrared light shielding properties are required.

[0142] For example, when this filter is used in an imaging device such as a digital still camera, an imaging device with excellent color reproducibility can be provided. An imaging device using this filter includes a solid-state imaging device, an imaging lens, and this filter. This filter can be used, for example, by being disposed between the imaging lens and the solid-state imaging device, or by being directly adhered to the solid-state imaging device, imaging lens, etc. of the imaging device via an adhesive layer.

Example

[0143] Next, the present invention will be described more specifically with reference to examples. For the measurement of each optical property, an ultraviolet-visible spectrophotometer (UH-4150 type, manufactured by Hitachi High-Technologies Corporation) was used. The spectroscopic 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).

[0144] The dyes used in each example are as follows. Note that Compounds 1 to 17 are UV dyes, and Compound 18 is a NIR dye. Compound 1 (merocyanine compound): Synthesized referring to Japanese Patent No. 6504176. Compound 2: Nikkafluor U1 manufactured by Nippon Kasei Co., Ltd. was used. Compound 3 (cyanine compound): SMP-416 manufactured by Hayashibara Chemical was used. Compound 4 (cyanine compound): SMP-370 manufactured by Hayashibara Chemical was used. Compound 5 (cyanine compound): manufactured by Hayashibara Chemical Industry Co., Ltd., using SMP-471. Compound 6: manufactured by Nippon Kayaku Co., Ltd., using Kayalight 408. Compound 7: manufactured by Nippon Kayaku Co., Ltd., using Kayalight B. Compound 8: manufactured by Nippon Kagaku Kogyo Co., Ltd., using Nikkafluor MCT. Compound 9 (merocyanine compound): synthesized referring to Japanese Patent No. 6504176. Compound 10 (merocyanine compound): synthesized referring to Japanese Patent No. 6504176. Compound 11 (benzoxazole compound): manufactured by Tokyo Chemical Industry Co., Ltd., UVITEX OB Compound 12 (merocyanine compound): synthesized referring to Japanese Patent No. 6504176. Compound 13 (merocyanine compound): synthesized referring to Japanese Patent No. 6504176. Compound 14 (azo compound): synthesized referring to Japanese Patent No. 6256335. Compound 15 (merocyanine compound): synthesized referring to Japanese Patent No. 6504176. Compound 16 (triazine compound): synthesized referring to Japanese Patent No. 6256335. Compound 17 (merocyanine compound): synthesized referring to Japanese Patent No. 6504176. Compound 18 (squarylium compound): synthesized referring to Japanese Patent No. 6197940.

[0145]

Chemical formula

[0146]

Chemical formula

[0147] <Test A: Spectroscopic properties of UV dyes in dichloromethane> Each dye was uniformly dissolved in dichloromethane. For each of the resulting solutions, the maximum absorption wavelength (λ) was measured using a spectrophotometer. max The absolute difference (UV70-UV10) between the wavelength UV10 with a transmittance of 10% and the wavelength UV70 with a transmittance of 70% in the 350-450 nm range was measured. The results are shown in the table below.

[0148] [Table 5]

[0149] <Test B: Spectral properties of UV dyes in resin> <Example 1-1> A polyimide resin (Mitsubishi Gas Chemical's Polyimide Varnish C-3G30G) diluted with an organic solvent (a mixed solvent of gamma-butyrolactone and cyclohexanone) was mixed with the UV dye of Compound 1 (2.5% by mass) and the NIR dye of Compound 18 (2.3% by mass), and the polyimide solution and dyes were thoroughly dissolved. The obtained resin solution was applied to a glass substrate (alkali glass, Shotto D263) using spin coating, and a 5 μm thick dye-containing polyimide thin film was fabricated by thoroughly heating and removing the organic solvent. The obtained thin film was subjected to transmission spectroscopy in the incident direction at 0 degrees in the wavelength range of 350 nm to 1200 nm using a spectrophotometer. The results are shown in the table below.

[0150] <Examples 1-2 to 1-16> A dye-containing resin thin film was prepared using the same method as in Example 1-1, except that the type of UV dye, the amount of UV dye added, the amount of NIR dye added, and the thickness of the resin thin film were set to the values ​​listed in the table below, and transmission spectroscopy was measured. The results are shown in the table below.

[0151] Examples 1-2, 1-5 to 1-11, 1-15, and 1-16 are examples, while examples 1-1, 1-3, 1-4, and 1-12 to 1-14 are comparative examples. T 440-480 : Average transmittance (%) in the spectral transmittance curve for wavelengths of 440-480 nm T 400-440 : Average transmittance (%) in the spectral transmittance curve with wavelengths of 400 - 440 nm T 370-400 : Average transmittance (%) in the spectral transmittance curve with wavelengths of 370 - 400 nm T 400 : Transmittance (%) in the spectral transmittance curve at a wavelength of 400 nm T 390 : Transmittance (%) in the spectral transmittance curve at a wavelength of 390 nm T 380 : Transmittance (%) in the spectral transmittance curve at a wavelength of 380 nm T 370 : Transmittance (%) in the spectral transmittance curve at a wavelength of 370 nm

[0152]

Table 6

[0153] From the above results, in Examples 1 - 2, 1 - 5 to 1 - 11, 1 - 15, 1 - 16 using UV dyes with a maximum absorption wavelength in the range of 360 - 395 nm in dichloromethane, the transmittance of blue light and the light-shielding property of ultraviolet light were high, showing excellent spectral characteristics. In Example 1 - 16 using a combination of two types of UV dyes, the spectral characteristics were particularly excellent. Although Example 1 - 2 had excellent spectral characteristics, it was necessary to increase the content of the UV dye and the thickness of the resin film to obtain the desired spectral characteristics.

[0154] <Example 2 - 1: Spectral Characteristics of Optical Filter> An ultraviolet and infrared cut multilayer film having a transmission band at 400 nm - 700 nm was formed on a glass substrate (alkali glass, D263 manufactured by Shotto). A resin thin film (absorption film) similar to that in Example 1 - 1 was fabricated by spin coating on the multilayer film. Then, a dielectric multilayer film (anti-reflection film) composed of SiO2 and TiO2 was formed by vapor deposition on the resin thin film to create an absorption type infrared cut filter. For the obtained infrared cut filter, the transmission spectra in the wavelength range of 350 nm - 1200 nm at incident directions of 0 deg and 50 deg were measured with a spectrophotometer. The results are shown in the following table.

[0155] <Examples 2-2 to 2-15> An infrared cut filter was prepared using the same method as in Example 2-1, except that the type of UV dye, the amount of UV dye added, the amount of NIR dye added, and the thickness of the resin thin film were set to the values ​​listed in the table below, and transmission spectroscopy was measured. The results are shown in the table below.

[0156] Furthermore, Figure 5 shows the spectral transmittance curve of the infrared cut filter for Example 2-14, and Figure 6 shows the spectral transmittance curve of the infrared cut filter for Example 2-15. The solid line represents the spectral transmittance curve at 0 degrees in the incident direction, and the dashed line represents the spectral transmittance curve at 50 degrees in the incident direction.

[0157] Examples 2-5, 2-6, 2-9, 2-10, and 2-15 are examples, while examples 2-1 to 2-4, 2-7, 2-8, and 2-11 to 2-14 are comparative examples.

[0158] λ max : Maximum absorption wavelength (nm) T 440-480 : Average transmittance (%) in the spectral transmittance curve for wavelengths of 440-480 nm T 400-440 : Average transmittance (%) in the spectral transmittance curve for wavelengths of 400-440 nm T 370-400(0deg) : Average transmittance (%) in the spectral transmittance curve at an incident angle of 0 degrees and a wavelength of 370-400 nm. T 370-400(50deg) : Average transmittance (%) in the spectral transmittance curve at an incident angle of 50 degrees and a wavelength of 370-400 nm UV10 (0deg) : Wavelength (nm) when the transmittance is 10% at wavelengths of 350-450 nm and an incident angle of 0 degrees. UV10 (50deg) : Wavelength (nm) when the transmittance is 10% at wavelengths of 350-450 nm and an incident angle of 50 degrees. UV20 (0deg) : Wavelength (nm) when the transmittance is 20% at wavelengths of 350-450 nm and an incident angle of 0 degrees. UV20 (50deg): Wavelength (nm) when the transmittance is 20% at wavelengths of 350-450 nm and an incident angle of 50 degrees. UV50 (0deg) : Wavelength (nm) at which transmittance is 50% at wavelengths of 350-450 nm and an incident angle of 0 degrees. UV50 (50deg) : Wavelength (nm) when the transmittance is 50% at wavelengths of 350-450 nm and an incident angle of 50 degrees. UV70 (0deg) : Wavelength (nm) at which the transmittance is 70% at wavelengths of 350-450 nm and an incident angle of 0 degrees. |UV70 (0deg) -UV10 (0deg) |:UV10 (0deg) and UV70 (0deg) The absolute value of the difference between |UV10 (50deg) -UV10 (0deg) |:UV10 (0deg) and UV10 (50deg) The absolute value of the difference (nm) |UV20 (50deg) -UV20 (0deg) |:UV20 (0deg) and UV20 (50deg) The absolute value of the difference (nm) |UV50 (50deg) -UV50 (0deg) |:UV50 (0deg) and UV50 (50deg) The absolute value of the difference (nm)

[0159] [Table 7]

[0160] Based on the above results, the optical filters in Examples 2-5, 2-6, 2-9, 2-10, and 2-15, which used UV dyes with a maximum absorption wavelength in dichloromethane in the range of 360-395 nm and whose solution spectroscopy (UV70-UV10) in Test A and resin spectroscopy in Test B were within the specified range, exhibited high transmittance of blue light and high shielding of ultraviolet light even at high incidence angles, demonstrating excellent spectral characteristics. Example 2-15, which used a combination of two types of UV dyes, showed particularly excellent spectral characteristics. On the other hand, the optical filters in examples 2-1, 2-3, 2-4, 2-12, 2-13, and 2-14, which did not meet the range of maximum absorption wavelength, and the optical filters in examples 2-2, 2-7, 2-8, and 2-11, whose solution spectroscopy in Test A was not within the specified range, showed poor transmission of blue light or poor shielding of ultraviolet light at high incidence angles.

[0161] <Example 3-1: Lightfastness Evaluation> A polyimide resin (Mitsubishi Gas Chemical's Polyimide Varnish C-3G30G) diluted with an organic solvent (a mixed solvent of gamma-butyrolactone and cyclohexanone) was mixed with the UV dye of Compound 1 (7.5% by mass), the UV dye of Compound 13 (3.5% by mass), and the NIR dye of Compound 18 (7% by mass), and the polyimide solution and dyes were thoroughly dissolved. The amount of dye added is indicated relative to the amount added to the resin. The obtained solution was coated onto a glass substrate (alkali glass, Shotto D263) by spin coating, and the organic solvent was removed by sufficient heating to produce a dye-containing polyimide film with a thickness of 1.5 μm. An anti-reflective coating similar to that in Example 2-1 was deposited onto the obtained polyimide film by vapor deposition. The obtained optical samples were subjected to a lightfastness test using a Super Xenon Weathermeter manufactured by Suga Test Instruments Co., Ltd. The incident surface was the surface with the anti-reflective coating. The light intensity is 80,000 J / mm² as an integrated light intensity in the wavelength range of 300-2450 nm. 2 The following was done. The remaining percentage of NIR dye was calculated from the absorption coefficients at 400 nm and 680 nm before and after the lightfastness test. The results are shown in the table below. Furthermore, a survival rate of 85% or higher at 400nm (T400nm survival rate) and 75% or higher at 680nm (T680nm survival rate) was considered to indicate excellent light resistance.

[0162] <Examples 3-2 to 3-10: Lightfastness Evaluation> The lightfastness test was conducted in the same manner as in Example 3-1, except that the type and content of the pigments were set to the values ​​listed in the table below. The results are shown in the table below.

[0163] Examples 3-1 to 3-4, 3-5, and 3-7 to 3-10 are examples, while Example 3-6 is a comparative example.

[0164] [Table 8]

[0165] From the results above, a comparison between Example 3-6 and Examples 3-4 to 3-5 shows that when UV dyes and NIR dyes are used together, the NIR dyes tend to degrade. Here, as shown in Examples 3-1 to 3-3, it can be seen that the degradation of NIR dyes can be suppressed by using a combination of multiple merocyanine compounds as UV dyes.

[0166] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2020-126700, filed on 27 July 2020, the contents of which are incorporated herein by reference. [Industrial applicability]

[0167] The optical filter of the present invention maintains good shielding of near-infrared light and transmittance of visible light, particularly blue light, while suppressing the decrease in ultraviolet light shielding performance, especially at high incidence angles. It is useful in applications such as information acquisition devices like cameras and sensors for transport aircraft, where performance has been steadily increasing in recent years. [Explanation of Symbols]

[0168] 1A, 1B, 1C, 1D... Optical filters, 10... Substrate, 11... Support, 12... Resin film, 30... Dielectric multilayer film

Claims

1. An optical filter comprising a substrate and a dielectric multilayer film laminated on at least one main surface side of the substrate, The substrate has a resin film comprising a dye (U) having a maximum absorption wavelength of 360 to 385 nm in dichloromethane, a dye (A) having a maximum absorption wavelength of 600 to 800 nm in dichloromethane, and a resin. The aforementioned dye (U) is a dye (U1) having a maximum absorption wavelength of 370 to 385 nm in dichloromethane. The resin film further contains a dye (U2) having a maximum absorption wavelength of 385 to 405 nm in dichloromethane. The optical filter is an optical filter that satisfies all of the following spectral characteristics (i-1) to (i-2) and (i-4). (i-1) Average transmittance T in the spectral transmittance curve at wavelengths of 440-480 nm ４４０－４８０ over 86% (i-2) The wavelength at which the transmittance is 10% at wavelengths of 350-450 nm and an incident angle of 0 degrees is defined as UV10. （０ｄｅｇ） The wavelength when the transmittance is 20% is UV20. （０ｄｅｇ） The wavelength when the transmittance is 50% is UV50. （０ｄｅｇ） year, UV10 is defined as the wavelength at which the transmittance is 10% at wavelengths of 350-450 nm and an incident angle of 50 degrees. （５０ｄｅｇ） The wavelength when the transmittance is 20% is UV20. （５０ｄｅｇ） The wavelength when the transmittance is 50% is UV50. （５０ｄｅｇ） In that case, UV10 （０ｄｅｇ） and UV10 （５０ｄｅｇ） and the absolute value of the difference is 3 nm or less UV20 （０ｄｅｇ） and UV20 （５０ｄｅｇ） The absolute value of the difference is 4 nm or less. UV50 （０ｄｅｇ） and UV50 （５０ｄｅｇ） The absolute value of the difference is 4 nm or less. (i-4) Average transmittance T in the spectral transmittance curve at wavelengths of 370-400 nm and incidence angle of 0 degrees ３７０－４００（０ｄｅｇ） less than 1%

2. The optical filter according to claim 1, wherein the optical filter further satisfies the following spectral characteristics (i-5). (i-5) Average transmittance T in the spectral transmittance curve at wavelengths of 370-400 nm and an incident angle of 50 degrees ３７０－４００（５０ｄｅｇ） less than 0.5%

3. The optical filter according to claim 1 or 2, wherein the optical filter further satisfies the following spectral characteristics (i-6). (i-6) The wavelength at which the transmittance is 10% at wavelengths of 350-450 nm and an incident angle of 0 degrees is defined as UV10. （０ｄｅｇ） The wavelength when the transmittance is 70% is UV70. （０ｄｅｇ） In that case, UV10 （０ｄｅｇ） and UV70 （０ｄｅｇ） The absolute value of the difference is 16 nm or less.

4. The optical filter according to any one of claims 1 to 3, wherein the thickness of the resin film is 10 μm or less.

5. The optical filter according to any one of claims 1 to 4, wherein the dye (U) satisfies all of the following spectral characteristics (ii-1) to (ii-6) in the spectral transmittance curve of a coating film obtained by dissolving the dye (U) in the resin and coating it on an alkali glass plate. (ii-1) Average transmittance T at wavelengths of 400-440 nm ４００－４４０ over 40% (ii-2) Average transmittance T at wavelengths of 370-400 nm ３７０－４００ less than 5% (ii-3) Transmittance T at a wavelength of 400 nm ４００ less than 7% (ii-4) Transmittance T at a wavelength of 390 nm ３９０ less than 5% (ii-5) Transmittance T at a wavelength of 380 nm ３８０ less than 5% (ii-6) Transmittance T at a wavelength of 370 nm ３７０ less than 5%

6. The optical filter according to any one of claims 1 to 5, wherein the optical filter further satisfies the following spectral characteristics (i-3). (i-3) Average transmittance T in the spectral transmittance curve at wavelengths of 400-440 nm ４００－４４０ over 40%

7. The optical filter according to any one of claims 1 to 5, wherein the absolute value of the difference in the maximum absorption wavelengths of the dye (U1) and the dye (U2) in the resin is 10 nm or more and 15 nm or less.

8. The optical filter according to any one of claims 1 to 7, wherein the substrate has a support, and the support is one of phosphate-based glass, boiling phosphate-based glass, alkali glass, alkali-free glass, or quartz glass.

9. The optical filter according to any one of claims 1 to 8, wherein the resin film is a single layer.

10. The optical filter according to any one of claims 1 to 9, having two or more layers of the aforementioned resin film.

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

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