Light absorption body, light absorbent compound, liquid dispersion of light absorbent compound, light absorbent composition, optical filter, photoelectric conversion element, ambient light sensor, and imaging device

Abstract

A light absorption body 10 has a transmission spectrum that satisfies conditions (I), (II), (III), (IV), and (V) at an entry angle of 0°. The light absorption body 10 has a haze of less than 0.20%. (I) The average value TA 0deg(460-600) is at least 75%. (II) The short wavelength-side cut-off wavelength λH 0deg(S) is 390-450 nm. (III) The long wavelength-side cut-off wavelength λH 0deg(L) is 600-680 nm. (IV) The average value TA 0deg(300-380) is at most 1.2%. (V) The average value TA 0deg(750-1000) is at most 1.2%.

Description

Light absorber, light absorbing compound, dispersion of light absorbing compound, light absorbing composition, optical filter, photoelectric conversion element, ambient light sensor, and imaging device

[0001] The present invention relates to a light absorber, a light absorbing compound, a dispersion of a light absorbing compound, a light absorbing composition, an optical filter, a photoelectric conversion element, an ambient light sensor, and an imaging device.

[0002] In an image capture device or ambient light sensor using a solid-state image sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), various optical filters are disposed in front of the solid-state image sensor. For example, in an image capture device, an optical filter may be used to obtain an image with good color reproducibility. In an ambient light sensor, an optical filter may be used to adjust the sensing of ambient light.

[0003] Generally, solid-state imaging devices have sensitivity over a wide wavelength range, from ultraviolet to infrared. However, human visual sensitivity is limited to wavelengths between approximately 380 nm and 780 nm, the so-called visible light range. Therefore, in order to bring the spectral sensitivity of the solid-state imaging device in an imaging device closer to the human visual sensitivity, a technique is known in which an optical filter is placed in front of the solid-state imaging device to block part of the infrared and ultraviolet light.

[0004] Among these, light-absorbing optical filters having a film or layer containing a light-absorbing agent have attracted attention. The transmittance characteristics of optical filters having a film containing a light-absorbing agent are less affected by the angle of incidence. Therefore, even when light is incident obliquely on an optical filter in an imaging device, for example, there is little change in color, there is little color unevenness within the surface, and good images with good reproducibility can be obtained. In addition, since light-absorbing optical filters do not use a light-reflecting film, the occurrence of ghosts or flares caused by multiple reflections due to light reflection can be suppressed, making it easier to obtain good images. Furthermore, optical filters having a film containing a light-absorbing agent are advantageous in terms of miniaturizing and thinning imaging devices.

[0005] For example, Patent Document 1 describes an optical filter including a UV-IR absorbing layer. This UV-IR absorbing layer contains a UV-IR absorber formed from phosphonic acid and copper ions, which is capable of absorbing ultraviolet and infrared rays. It also describes that the haze of the UV-IR absorbing layer is 5% or less. The haze of the UV-IR absorbing layer is 5% or less. For example, by incorporating an optical filter including such a UV-IR absorbing layer into an imaging device, high-quality images can be obtained.

[0006] Patent No. 6606626

[0007] The technology described in Patent Document 1 needs to be reconsidered from the viewpoint of improving the performance of optical filters. Therefore, the present invention provides a light absorber that is advantageous from the viewpoint of improving the performance of optical filters.

[0008] The present invention provides a light absorber having a transmission spectrum that satisfies the following conditions (I), (II), (III), (IV), and (V) at an incident angle of 0°, and having a haze of less than 0.20%. (I) The average transmittance in the wavelength range of 460 nm to 600 nm is 75% or more. (II) The short-wavelength cutoff wavelength at which the transmittance is 50% in the wavelength range of 350 nm to 450 nm is 390 nm to 450 nm. (III) The long-wavelength cutoff wavelength at which the transmittance is 50% in the wavelength range of 600 nm to 700 nm is 600 nm to 680 nm. (IV) The average transmittance in the wavelength range of 300 nm to 380 nm is 1.2% or less. (V) The average transmittance in the wavelength range of 750 nm to 1100 nm is 1.2% or less.

[0009] The present invention also provides a light-absorbing compound comprising: a first light-absorbing compound containing a copper component and a first phosphonic acid represented by the following formula (a); and a second light-absorbing compound containing a copper component and a second phosphonic acid represented by the following formula (b), wherein in formula (a), R1 is an alkyl group or a halogenated alkyl group in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom; and in formula (b), R2 is an aryl group or a modified aryl group in which at least one hydrogen atom in the aryl group is substituted with a halogen atom, a nitro group, or a hydroxy group, and the transmission spectrum of a dispersion of the light-absorbing compound satisfies the following conditions (i), (ii), (iii), and (iv): (i) the average value of the transmittance in the wavelength range of 460 nm to 600 nm is 85% or more; and (ii) the short-wavelength-side cutoff wavelength at which the transmittance is 50% in the wavelength range of 350 nm to 450 nm is 380 nm to 420 nm. (iii) The cutoff wavelength on the long wavelength side where the transmittance is 50% in the wavelength range of 600 nm to 700 nm is 600 nm to 650 nm. (iv) The average transmittance in the wavelength range of 725 nm to 1000 nm is 5% to 20%.

[0010]

[0011] The present invention also provides a dispersion liquid of a light-absorbing compound comprising: a light-absorbing compound; a solvent; and an alkoxysilane or an alkoxysilane hydrolysate, wherein the light-absorbing compound comprises a first light-absorbing compound comprising a copper component and a first phosphonic acid represented by the following formula (a), and a second light-absorbing compound comprising a copper component and a second phosphonic acid represented by the following formula (b), wherein in the following formula (a), R1 is an alkyl group or a halogenated alkyl group in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom, and in the following formula (b), R2 is an aryl group or a modified aryl group in which at least one hydrogen atom in the aryl group is substituted with a halogen atom, a nitro group, or a hydroxy group.

[0012]

[0013] The present invention also provides a light-absorbing composition comprising: a first light-absorbing compound containing a copper component and a first phosphonic acid represented by the following formula (a); a second light-absorbing compound containing a copper component and a second phosphonic acid represented by the following formula (b); a solvent; and a binder, wherein in the following formula (a), R1 is an alkyl group or a halogenated alkyl group in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom; and in the following formula (b), R2 is an aryl group or a modified aryl group in which at least one hydrogen atom in the aryl group is substituted with a halogen atom, a nitro group, or a hydroxy group, and the ratio of the content of the second phosphonic acid to the content of the first phosphonic acid is 1.8 to 9 on a mass of substance basis.

[0014]

[0015] The present invention also provides an optical filter comprising the above light absorber.

[0016] The present invention also provides a photoelectric conversion element comprising a light receiving surface and the above light absorber, wherein the light receiving surface and the light absorber are arranged in this order.

[0017] The present invention also provides an ambient light sensor including the above optical filter.

[0018] The present invention also provides an imaging device including the above optical filter.

[0019] The above light absorber is advantageous from the viewpoint of improving the performance of the optical filter.

[0020] FIG. 1A is a cross-sectional view showing an example of an optical filter according to the present invention. FIG. 1B is a cross-sectional view showing another example of an optical filter according to the present invention. FIG. 1C is a cross-sectional view showing yet another example of an optical filter according to the present invention. FIG. 1D is a cross-sectional view showing yet another example of an optical filter according to the present invention. FIG. 1E is a cross-sectional view showing yet another example of an optical filter according to the present invention. FIG. 1F is a cross-sectional view showing yet another example of an optical filter according to the present invention. FIG. 2A is a cross-sectional view showing an example of an ambient light sensor according to the present invention. FIG. 2B is a cross-sectional view showing an example of a photoelectric conversion element according to the present invention. FIG. 3A is a diagram showing an example of an imaging device according to the present invention. FIG. 3B is a diagram showing another example of an imaging device according to the present invention. FIG. 4 is a graph showing an example of the transmission spectrum of the base material shown in FIG. 1B. FIG. 5A is a graph showing the transmission spectrum at each incident angle of the light absorber according to Example 1. FIG. 5B is a graph showing the reflection spectrum at each incident angle of the light absorber according to Example 1. FIG. 5C is a graph showing the transmission spectrum of a dispersion of a light-absorbing compound according to Example 1. FIG. 6 is a graph showing the transmission spectrum at each incident angle of the light absorber according to Example 2. FIG. 7 is a graph showing the transmission spectrum at each incident angle of the light absorber according to Example 3. FIG. 8A is a graph showing the transmission spectrum at each incident angle of the light absorber according to Example 4. FIG. 8B is a graph showing the transmission spectrum of a dispersion of a light-absorbing compound according to Example 4. FIG. 9A is a graph showing the transmission spectrum at each incident angle of the light absorber according to Example 5. FIG. 9B is a graph showing the reflection spectrum at each incident angle of the light absorber according to Example 5. FIG. 9C is a graph showing the transmission spectrum of a dispersion of a light-absorbing compound according to Example 5. FIG. 10 is a graph showing the transmission spectrum at each incident angle of the light absorber according to Example 6. FIG. 11 is a graph showing the transmission spectrum at each incident angle of the light absorber according to Example 7. FIG. 12A is a graph showing the transmission spectrum at each incident angle of the light absorber according to Example 8. FIG. 12B is a graph showing the reflection spectrum at each incident angle of the light absorber according to Example 8. FIG. 12C is a graph showing the transmission spectrum of a dispersion of a light-absorbing compound according to Example 8.FIG. 13 is a graph showing the reflection spectrum at each incident angle of the light absorber according to Example 9. FIG. 14A is a graph showing the transmission spectrum at an incident angle of 0° of the light absorber according to Example 10. FIG. 14B is a graph showing the transmission spectrum of a dispersion of a light-absorbing compound according to Example 10. FIG. 15 is a graph showing the transmission spectrum at an incident angle of 0° of the light absorber according to Example 11. FIG. 16 is a graph showing the transmission spectrum at an incident angle of 0° of the light absorber according to Example 12. FIG. 17A is a graph showing the transmission spectrum at each incident angle of the optical filter according to Example 13. FIG. 17B is a graph showing the reflection spectrum at each incident angle of the optical filter according to Example 13. FIG. 18 is a graph showing the transmission spectrum at an incident angle of 0° of the light absorber according to Comparative Example 1. FIG. 19 is a graph showing the transmission spectrum at an incident angle of 0° of the light absorber according to Comparative Example 2. FIG. 20A is a graph showing the transmission spectrum at an incident angle of 0° of the light absorber according to Reference Example 1. Fig. 20B is a graph showing the transmission spectrum at an incident angle of 0° and the rate of change in transmittance with respect to wavelength of the light absorber according to Reference Example 1. Fig. 21A is a graph showing the transmission spectrum at an incident angle of 0° of the light absorber according to Reference Example 1. Fig. 21B is a graph showing the transmission spectrum at an incident angle of 0° of the light absorber according to Reference Example 1 and the rate of change in transmittance with respect to wavelength.

[0021] With the global spread of information terminals such as smartphones equipped with camera modules, the demand for the quality and performance of images captured by cameras is increasing day by day. Therefore, there is a strong demand for higher performance in optical filters incorporated into imaging devices or camera modules. In particular, for optical filters that block ultraviolet and infrared rays, the specifications for their transmission spectrum are becoming stricter and more detailed, and there is also a strong demand for minimizing their haze.

[0022] Patent Document 1 describes the content of copper ions contained in a composition for forming a UV-IR absorbing layer, and also describes a preferred range of viscosity of a liquid composition that is a precursor of the UV-IR absorbing layer. Meanwhile, the haze value of the UV-IR absorbing layer described in Patent Document 1 is at least 0.2%. If a light absorber that can achieve a smaller haze while blocking ultraviolet and infrared rays could be provided, the performance of, for example, optical filters could be further improved. After extensive research, the present inventors have finally discovered a light absorber that can achieve both a smaller haze and predetermined transmission characteristics that can block ultraviolet and infrared rays.

[0023] Hereinafter, embodiments of the present invention will be described. Note that the following description is for illustrative purposes only and the present invention is not limited to the following embodiments.

[0024] Fig. 1A is a cross-sectional view showing an optical filter 1a. As shown in Fig. 1A, the optical filter 1a includes a light absorber 10. The light absorber 10 has a transmission spectrum that satisfies the following conditions (I), (II), (III), (IV), and (V) at an incident angle of 0°. In addition, the light absorber 10 has a haze of less than 0.20%. (I) The average transmittance T in the wavelength range of 460 nm to 600 nm A (II) The cutoff wavelength λ on the short wavelength side at which the transmittance is 50% in the wavelength range of 350 nm to 450 nm is 75% or more. H 0deg(S) (III) The cutoff wavelength λ on the long wavelength side at which the transmittance is 50% in the wavelength range of 600 nm to 700 nm is 390 nm to 450 nm. H 0deg(L) (IV) The average value T of the transmittance in the wavelength range of 300 nm to 380 nm A 0 deg (300-380) is 1.2% or less. (V) Average transmittance T in the wavelength range of 750 nm to 1100 nm A 0deg (750-1000) is less than 1.2%.

[0025] In the light absorber 10, the transmittance in the visible light region is likely to be high when the conditions (I), (II), and (III) are satisfied, and in particular, the transmittance in the red band of the light absorber is likely to be high when the condition (III) is satisfied. In addition, when the condition (V) is satisfied, the light absorber 10 can effectively block infrared rays.

[0026] As shown in FIG. 1A, the light absorber 10 can be distributed alone as an optical filter 1a. The light absorber 10 may be in the form of a film or membrane that absorbs a portion of light. It may also be in the form of a partial layer constituting a functional film that also has other functions. The optical filter 1a may be configured like the optical filter 1b shown in FIG. 1B. The optical filter 1b includes a substrate 20 in addition to the light absorber 10. For example, the light absorber 10 may be formed so as to cover at least a portion of the surface of the substrate 20. The substrate 20 includes, for example, resin, glass, and metal. An example of the substrate 20 is Corning's D263T eco. The D263T eco, which has a thickness of 3 mm, has the transmission spectrum shown in FIG. 4 at an incident angle of 0°. In the transmission spectrum shown in FIG. 4, the transmittance in the wavelength range of 360 nm to 2300 nm is 90% or more, and the transmittance in the wavelength range of 335 nm to 2500 nm is 85% or more.

[0027] The transmission spectrum is determined, for example, by irradiating a predetermined object with light having a wavelength of 300 nm to 1200 nm at a predetermined angle of incidence (IA) and measuring the transmitted light with a spectrophotometer, etc. The reflection spectrum is determined by irradiating a predetermined object with light having a wavelength of 300 nm to 1200 nm at a predetermined angle of incidence and measuring the reflected light with a spectrophotometer, etc.

[0028] The light absorber 10 alone may satisfy the requirements regarding the transmission spectrum, or an optical filter including a substrate and the light absorber 10 may satisfy the requirements regarding the transmission spectrum. In other words, an optical filter including a substrate and the light absorber 10 may satisfy the above conditions (I), (II), (III), (IV), and (V) at an incident angle of 0°, or may satisfy the requirements regarding the transmission spectrum described below for the light absorber 10.

[0029] In this specification, unless otherwise specified, the visible light range or visible light region is defined as a wavelength range of 380 to 780 nm, and the red band is defined as a wavelength range of 580 to 780 nm or a portion of that range. Furthermore, unless otherwise specified, infrared light is defined as light (electromagnetic waves) having a wavelength greater than 780 nm, the upper limit of the visible light range, and ranging up to 1400 nm, and corresponds to near-infrared light (NIR). Ultraviolet light is defined as light (electromagnetic waves) having a wavelength ranging from 280 nm to 380 nm, the lower limit of the visible light range, and corresponds to UV-A and portions of UV-B.

[0030] Optical filters incorporated into ambient light sensors, imaging devices, and the like are naturally required to have appropriate transmission and reflection spectra. On the other hand, even if the transmittance in the visible light range is high, for example, if the haze is high, some of the light incident on the optical filter or light absorber may be scattered or diffused within the filter, resulting in cloudiness and opacity. This may affect the formation of sharp images. Meanwhile, the light absorber 10 satisfies the above conditions (I), (II), (III), (IV), and (V) and has a haze of less than 0.20%, which tends to increase the transparency of the optical filter while maintaining the desired transmission spectrum. Therefore, the light absorber 10 is suitable from the perspective of improving the quality of images acquired by imaging devices. Additionally, the light absorber 10 tends to improve the accuracy of ambient light sensing in ambient light sensors.

[0031] The haze value of the light absorber 10 may be determined by measuring the light absorber 10 alone, or may be determined by measuring an optical filter in which the light absorber 10 is provided on a substrate such as glass or resin.

[0032] The haze of the light absorber 10 may be 0.19% or less, preferably 0.18% or less, and more preferably 0.15% or less.

[0033] Regarding the above condition (I), the average value T A The transmittance at 0 degrees (460-600) is preferably 80% or more, and more preferably 85% or more. Furthermore, in the transmission spectrum of the light absorber 10 within a wavelength range of 300 nm to 1100 nm at an incident angle of 0 degrees, the wavelength corresponding to the maximum value of the transmittance may be within a range of 500 nm to 600 nm. In this case, since the region with the highest visibility in the human visibility spectrum (visibility curve) is between 500 nm and 600 nm, it is expected that an impressively brighter image will be obtained.

[0034] Regarding the above condition (II), the short wavelength cutoff wavelength λ H 0deg(S) is desirably 400 nm to 450 nm, may be 400 nm to 440 nm, may be 400 nm to 430 nm, or may be 400 nm to 420 nm.

[0035] Regarding the above condition (III), the long wavelength cutoff wavelength λ H 0deg(L) is preferably 610 nm to 680 nm, and more preferably 620 to 680 nm. H 0deg(L) may be 620 nm to 670 nm, or may be 620 nm to 660 nm.

[0036] Regarding the above condition (IV), the average value T A 0 deg (300-380) is preferably 1% or less, and more preferably 0.5% or less.

[0037] Regarding the above condition (V), the average value T A 0 deg (750-1000) is preferably 1% or less, and more preferably 0.5% or less.

[0038] The light absorber 10 may have a reflectance spectrum that satisfies, for example, the following conditions (VI) and (VII) at an incident angle of 5°: (VI) Maximum reflectance R within a wavelength range of 300 nm to 400 nm M 5 deg (300-400) is 7.5% or less. (VII) The maximum reflectance R in the wavelength range of 700 nm to 1200 nm M 5deg (700-1200) is less than 7.5%.

[0039] By satisfying the above conditions (VI) and (VII), when an optical filter including the light absorber 10 is incorporated into an imaging device, it is possible to prevent a portion of the light reflected from the optical filter from being reflected by the surfaces of the optical system, such as the housing, frame, or aperture and lens, that constitute the imaging device, or from being projected onto the aperture or its shape and entering the imaging element. This can prevent harmful light that does not contribute to image formation, such as ghosts and flares, from entering the imaging element. Furthermore, this characteristic allows an optical filter that functions to block a portion of light to achieve its purpose through the action and function of the light absorber 10 alone, without using a light-reflecting film formed of a dielectric multilayer film or the like.

[0040] Regarding the above condition (VI), the maximum value R M 5 deg (300-400) is preferably 7.0% or less, more preferably 6.5% or less, and even more preferably 6% or less.

[0041] Regarding the above condition (VII), the maximum value R M 5 deg (700-1200) is preferably 7.0% or less, more preferably 6.5% or less, and even more preferably 6% or less.

[0042] The light absorber 10 may have a transmission spectrum that satisfies the following conditions (1-i), (1-ii), (1-iii), and (1-iv) at incident angles of, for example, 0°, 40°, 50°, 60°, and 70°. H 40deg(S) , λ H 50deg(S) , λ H 60deg(S) , and λH 70deg(S) are the short wavelength cutoff wavelengths at which the transmittance is 50% in the wavelength range of 350 nm to 450 nm at incident angles of 40°, 50°, 60°, and 70°, respectively. H 40deg(S) -λ H 0deg(S) ≦2.5nm (1-ii)λ H 50deg(S) -λ H 0deg(S) ≦4.5nm (1-iii)λ H 60deg(S) -λ H 0deg(S) ≦7.5nm (1-iv)λ H 70deg(S) -λ H 0deg(S) ≦20 nm

[0043] The light absorber 10 may have a transmission spectrum that satisfies the following conditions (2-i), (2-ii), (2-iii), and (2-iv) at incident angles of, for example, 0°, 40°, 50°, 60°, and 70°. H 40deg(L) , λ H 50deg(L) , λ H 60deg(L) , and λ H 70deg(L) are the cutoff wavelengths on the long wavelength side at which the transmittance is 50% in the wavelength range of 600 nm to 700 nm at incident angles of 40°, 50°, 60°, and 70°, respectively. H 0deg(L) -λ H 40deg(L) ≦4 nm (2-ii) λ H 0deg(L) -λ H 50deg(L) ≦7nm (2-iii)λ H 0deg(L) -λ H 60deg(L) ≦12nm (2-iv)λ H 0deg(L) -λ H 70deg(L) ≦30 nm

[0044] By satisfying the conditions (1-i) to (1-iv) and (2-i) to (2-iv), when an optical filter including the light absorber 10 is incorporated into an imaging device, a difference in color is unlikely to occur between a region that contributes to the formation of an image by light incident on the optical filter at a small angle of incidence and a region that contributes to the formation of an image by light incident on the optical filter at a relatively large angle of incidence. Specifically, a difference in color is unlikely to occur between the center and periphery of an acquired image, and a difference in color is unlikely to occur even in an image acquired by an imaging device having a wide-angle lens or an ultra-wide-angle lens.

[0045] The light absorber 10 typically contains a predetermined light absorbing agent. The light absorbing agent contained in the light absorber is not limited to a specific substance as long as the transmission spectrum of the light absorber 10 at an incident angle of 0° satisfies the above conditions (I) to (V) and the light absorber 10 has a haze of less than 0.20%.

[0046] The light absorber 10 can be manufactured by, for example, curing a liquid light-absorbing composition. The light absorber 10 may be a film or a membrane formed on a predetermined object such as glass or resin, and may exist in a solid state.

[0047] The light-absorbing composition contains a light-absorbing compound and a binder. A dispersion of the light-absorbing compound may be used to prepare the light-absorbing composition. The compound or its precursor that provides the light absorber 10 with a predetermined transmission spectrum, reflection spectrum, or low haze value may naturally be contained in the light-absorbing composition, which is the precursor of the light absorber 10, and in a dispersion in which the light-absorbing compound contained in the light-absorbing composition is dispersed. Hereinafter, a dispersion of the light-absorbing compound is also referred to as a light-absorbing dispersion. Like the light-absorbing composition, the light-absorbing dispersion contains a light-absorbing compound, but differs in that it does not contain a compound that hardens upon heating or irradiation with electromagnetic waves such as light. "Curing" a resin refers to the reaction of some of its functional groups with heating, standing, or irradiation with electromagnetic waves such as light, resulting in polymerization and the formation of a polymer structure that hardens and becomes irreversible.

[0048] The light-absorbing composition includes, for example, a light-absorbing compound, a solvent, and a binder. The light-absorbing composition may further include a dispersant, if necessary. The dispersant contributes to dispersing the light-absorbing compound in the solvent. The light-absorbing composition may be a precursor to a light absorber and have curing properties, such that it is cured by heating or irradiation with electromagnetic waves. Furthermore, the light-absorbing composition is not limited to a specific composition as long as it satisfies the above requirements (I) to (V) when cured into a light absorber. The haze of the light absorber is desirably less than 0.20%.

[0049] Examples of the light absorbing compound include a compound containing a phosphonic acid and a copper component, a compound containing a phosphate ester and a copper component, a compound containing a phosphoric acid and a copper component, M n Cu y P.O. 4-z The light absorber 10 may be a phosphoric acid-copper complex represented by the formula (where M is a metal element other than Cu), a compound containing sulfonic acid and a copper component, a compound containing tungsten oxide, a metal oxide such as ITO and ATO, or a known organic dye-based compound. Examples of organic dye-based compounds are diimmonium-based compounds, cyanine-based compounds, squarylium-based compounds, phthalocyanine-based compounds, and pyrrolopyrrole-based compounds. For example, the light absorber 10 may contain a light-absorbing compound containing phosphonic acid and a copper component as a light absorber, and may also contain an ultraviolet absorber that absorbs at least a portion of ultraviolet light.

[0050] Among these, compounds having a wide absorption band in the infrared region, such as compounds containing phosphonic acid and a copper component, compounds containing phosphate ester and a copper component, compounds containing phosphoric acid and a copper component, compounds containing sulfonic acid and a copper component, and complexes of these compounds, are advantageous as light absorbers. This is because blocking of light in a predetermined wavelength range can be achieved solely through the light absorption action of the light absorber 10. In the light absorber 10, these compounds may be used alone, or multiple types of compounds may be mixed and used. Furthermore, phosphonic acid, phosphate ester, and phosphoric acid are oxides containing phosphorus (P), and these may coexist. For example, the light absorber 10 may contain a compound containing phosphonic acid, a phosphate ester, and a copper component. Even when a complex containing phosphonic acid and a copper component is obtained as a light absorber, a phosphate ester may be added as a dispersant. In this case, a compound containing phosphonic acid, a phosphate ester, and a copper component may be included in the light absorber 10.

[0051] The phosphonic acid in the light-absorbing compound is not limited to a specific phosphonic acid, as long as the transmission spectrum of the light absorber 10 at an incident angle of 0° satisfies the conditions (I) to (V) and the light absorber 10 has a haze of less than 0.20%. The phosphonic acid includes, for example, a primary phosphonic acid represented by the following formula (a): In formula (a), R1 is an alkyl group or a halogenated alkyl group in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom. In this case, the transmission band of the light absorber 10 is likely to extend to a wavelength of approximately 700 nm, and the light absorber 10 is likely to have the desired transmittance characteristics. Phosphonic acids having these groups are collectively referred to as alkylphosphonic acids. The phosphonic acid in the light-absorbing compound includes, for example, a secondary phosphonic acid represented by the following formula (b): In formula (b), R2 is an aryl group or a modified aryl group in which at least one hydrogen atom in the aryl group is substituted with a halogen atom, a nitro group, or a hydroxy group. This makes it even easier for the optical filter 1a to have the desired transmittance characteristics. Phosphonic acids having these groups are collectively called arylphosphonic acids. The modified aryl group is, for example, a halogenated phenyl group.

[0052]

[0053] The primary phosphonic acid is, for example, methylphosphonic acid, ethylphosphonic acid, normal (n-)propylphosphonic acid, isopropylphosphonic acid, normal (n-)butylphosphonic acid, isobutylphosphonic acid, sec-butylphosphonic acid, tert-butylphosphonic acid, or bromomethylphosphonic acid.

[0054] The secondary phosphonic acid is, for example, phenylphosphonic acid, bromophenylphosphonic acid, benzylphosphonic acid, fluorophenylphosphonic acid, iodophenylphosphonic acid, nitrophenylphosphonic acid, hydroxyphenylphosphonic acid, tolylphosphonic acid, xylylphosphonic acid, naphthylphosphonic acid.

[0055] The light absorber 10, the light absorbing composition, and the light absorbing dispersion may contain one or more types of phosphonic acids selected from the above-mentioned phosphonic acids.

[0056] The phosphonic acid contained in the light absorber 10, the light-absorbing composition, and the light-absorbing dispersion may include a first phosphonic acid and a second phosphonic acid. In this case, the phosphonic acid may include one or more types of first phosphonic acids, and may include one or more types of second phosphonic acids. In the light absorber 10, the light-absorbing composition, and the light-absorbing dispersion, a first light-absorbing compound and a second light-absorbing compound may be present. The first light-absorbing compound includes a copper component and a first phosphonic acid. The second light-absorbing compound includes a copper component and a second phosphonic acid.

[0057] In the light absorber 10, the light-absorbing composition, and the light-absorbing dispersion, the ratio α of the content of the second phosphonic acid to the content of the first phosphonic acid ar / ak is not limited to a specific value. ar / ak is, for example, 1.8 to 9 on a substance amount basis. If some compounds aggregate and precipitate as lumps in the preparation of a light-absorbing composition or a light-absorbing dispersion, the haze of the light absorber increases, making the light absorber less suitable for an imaging device. ar / akBy making the ratio α 9 or less, it is possible to prevent some compounds from aggregating and forming lumps and settling during the preparation of the light-absorbing composition or light-absorbing dispersion. Therefore, the haze of the light absorber 10 is likely to be less than 0.20%. ar / ak By making the ratio 1.8 or more, it is possible to prevent the short-wavelength-side cutoff wavelength from becoming shorter than a predetermined range and the long-wavelength-side cutoff wavelength from becoming longer than a predetermined range. As a result, the transmittance of the light absorber 10 in the visible light range is likely to be high.

[0058] ratio α ar / ak When the ratio is 1.8 or more, it is easy to prevent at least one step from appearing in the curve of the transmission spectrum of the light absorber or optical filter in the wavelength range of 420 nm to 480 nm. max and the minimum value dT / dλ min The difference between the transmittance and the wavelength is 0.2 [% / nm] or more, or the minimum value of the rate of change of transmittance with respect to wavelength dT / dλ min If the value of dT / dλ is 0.2 [% / nm] or less, such a step may appear significantly. In dT / dλ, T is the transmittance [%] and λ is the wavelength [nm]. The appearance of such a step may cause adverse effects when a light absorber or optical filter is applied to an imaging device or an ambient light sensor.

[0059] ratio α ar / ak is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, particularly preferably 5.5 or more, and especially preferably 6.0 or more. ar / ak is preferably 8.5 or less, more preferably 8.0 or less, and even more preferably 7.5 or less.

[0060] In the light absorber 10, the light-absorbing composition, and the light-absorbing dispersion, the copper component is a concept that encompasses copper ions, copper complexes, and copper-containing compounds. The copper component can have favorable absorption characteristics for a portion of light in the near-infrared region and high transmittance for light in the wavelength range of 450 nm to 680 nm included in the visible light region. Specifically, excellent near-infrared absorption characteristics are exhibited by selectively absorbing light of wavelengths in the near-infrared region corresponding to this energy through the transition of electrons in the d orbital of the divalent copper ion. In particular, the copper component containing divalent copper ions can be supplied in the form of a copper salt and mixed with phosphonic acid, and the phosphonic acid can be coordinated to the copper component containing copper ions to form a copper complex (copper salt).

[0061] The source of the copper component to be coordinated with the phosphonic acid may be, but is not limited to, an anhydrous or hydrated copper salt of an organic acid such as copper acetate, copper benzoate, copper pyrophosphate, or copper stearate, or a mixture thereof. These copper salts may be used alone, or multiple copper salts or a mixture of multiple copper salts may be used.

[0062] In the light absorber 10, the light absorbing composition, and the light absorbing dispersion, the ratio α of the content of the phosphonic acid to the content of the copper component PC is not limited to a specific value. PC is, for example, 0.3 to 3 on a substance basis. When both primary phosphonic acid and secondary phosphonic acid are included, the ratio α PC can be the ratio of the sum of the content of the first phosphonic acid and the content of the second phosphonic acid to the content of the copper component. PC When the ratio is in the range of 0.3 to 3, each element or group is likely to constitute the light absorber in just the right amount, which makes it difficult for oxidation to occur in the light absorber 10, the light absorbing composition, and the light absorbing dispersion, and makes it easy for good weather resistance to be exhibited.

[0063] ratio α PC is preferably 0.4 to 2, more preferably 0.6 to 1.2, based on the amount of substance.

[0064] In the light absorber 10, the light absorbing composition, and the light absorbing dispersion, when both a first phosphonic acid and a second phosphonic acid are contained, the ratio αak / c and ratio α ar / c Each of the ratios α ak / c is the ratio of the content of primary phosphonic acid to the content of copper component, and the ratio α ar / c is the ratio of the content of secondary phosphonic acid to the content of copper component. ak / c is, for example, 0.05 to 0.8 on a substance basis. ak / c is preferably 0.1 to 0.4, and more preferably 0.1 to 0.3. ar / c is, for example, 0.2 to 1.5, preferably 0.4 to 1.2, and more preferably 0.5 to 1, based on the amount of substance.

[0065] The light absorber 10, the light-absorbing composition, and the light-absorbing dispersion may further contain a phosphate ester compound. The phosphate ester facilitates proper dispersion of the light-absorbing compound (light absorber) in the light absorber 10, the light-absorbing composition, and the light-absorbing dispersion. The phosphate ester may function as a dispersant for the light-absorbing compound, or a portion of the phosphate ester may react with a metal component to form the light-absorbing compound. For example, the phosphate ester may be coordinated to the light-absorbing compound, or may react with another portion of the compound, or may partially form a complex with the copper component. As long as the transmission spectrum of the light absorber 10 at an incident angle of 0° satisfies the conditions (I) to (V), the compound containing the phosphate ester and the copper component may also absorb light of some wavelengths. The phosphate ester may be substantially absent, or may not be present at all, as long as the light-absorbing compound containing at least a phosphonic acid and a copper component is properly dispersed in the light-absorbing composition or light-absorbing dispersion, which is the precursor of the light absorber. For example, when an alkoxysilane monomer, which will be described later, is contained as a dispersant in the light-absorbing composition, it is possible to reduce the amount of phosphate ester added.

[0066] The phosphate ester is not limited to a specific phosphate ester or compound thereof. The phosphate ester may have, for example, a polyoxyalkyl group. Examples of such phosphate esters include Plysurf A208N: polyoxyethylene alkyl (C12, C13) ether phosphate ester, Plysurf A208F: polyoxyethylene alkyl (C8) ether phosphate ester, Plysurf A208B: polyoxyethylene lauryl ether phosphate ester, Plysurf A219B: polyoxyethylene lauryl ether phosphate ester, Plysurf AL: polyoxyethylene styrenated phenyl ether phosphate ester, Plysurf A212C: polyoxyethylene tridecyl ether phosphate ester, and Plysurf A215C: polyoxyethylene tridecyl ether phosphate ester. All of these are products manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Additionally, examples of phosphate esters include NIKKOL DDP-2: polyoxyethylene alkyl ether phosphate ester, NIKKOL DDP-4: polyoxyethylene alkyl ether phosphate ester, and NIKKOL DDP-6: polyoxyethylene alkyl ether phosphate ester, all of which are products manufactured by Nikko Chemicals Co., Ltd. These phosphate ester compounds may be used alone or in combination.

[0067] In the light absorber 10, the light absorbing composition, and the light absorbing dispersion, the ratio β of the content of phosphonic acid to the content of phosphoric acid ester p / es is not limited to a specific value. p / es is, for example, 1 to 3 on a mass basis. This suppresses hydrolysis of the phosphate ester even when the light absorber 10 comes into contact with water vapor or moisture, and the light absorber 10 is likely to have good weather resistance. The ratio of the content of phosphonic acid to the content of phosphate ester in the light absorber 10 is preferably 1.2 to 3.8, and more preferably 1.5 to 2.5.

[0068] The light absorber 10, light-absorbing composition, and light-absorbing dispersion may further contain, for example, an alkoxysilane or an alkoxysilane hydrolysate. Examples of alkoxysilanes include alkoxysilane monomers, partial hydrolysis of alkoxysilane monomers, and at least partial polymerization of alkoxysilane hydrolysates to form dimers or polymers. The presence of alkoxysilanes can prevent light-absorbing agent particles from agglomerating, so even if the content of phosphate ester is reduced, the light absorber is easily dispersed well in the light-absorbing composition or a light absorber cured therefrom. Furthermore, for example, when a light absorber or optical filter is manufactured using the light-absorbing composition, a siloxane bond (—Si—O—Si—) is formed by treating the composition so that the hydrolysis reaction and condensation polymerization reaction of the alkoxysilane monomer occur sufficiently, and the light absorber has good moisture resistance. In addition, the light absorber has good heat resistance. This is because siloxane bonds have higher bond energy and are more chemically stable than bonds such as —C—C— and —C—O— bonds, and therefore have excellent heat and moisture resistance.

[0069] When the light-absorbing composition contains an alkoxysilane, the light-absorbing composition may be exposed to a relatively humid atmosphere for a certain period of time during curing to produce a light absorber, which is called a humidification treatment. It is believed that the water component in the atmosphere promotes hydrolysis of the alkoxysilane contained in the light-absorbing composition or the light absorber, thereby promoting the formation of siloxane bonds. Furthermore, the humidification treatment facilitates the formation of a hard, dense light absorber without agglomerating fine particles containing the light absorber.

[0070] The alkoxysilane is not limited to a specific alkoxysilane as long as it can form a hydrolysis-condensation polymerization compound having a siloxane bond in the light absorber through hydrolysis and condensation polymerization. The alkoxysilane may be, for example, a monomer such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, or 3-glycidoxypropylmethyldiethoxysilane, or a dimer or oligomer in which a part of these is bonded.

[0071] The binder contained in the light absorber 10 and the light-absorbing composition may contain a curable resin. The curable resin is not limited to a specific resin. The curable resin can, for example, disperse or dissolve the light-absorbing compound containing the above-mentioned phosphonic acid and copper component or other light-absorbing compounds. The curable resin is preferably a liquid resin in an uncured or unreacted state, and can disperse or dissolve at least the light-absorbing compound containing the above-mentioned phosphonic acid and copper component. Furthermore, the curable resin, when uncured and liquid, can be applied to a predetermined object by methods such as spin coating, spray coating, dip coating, and dispensing to form a coating film. The object on which the coating film is formed is a substrate having a predetermined surface, whether flat or curved. The uncured liquid resin can be cured by heating, humidifying, irradiating with energy such as light, or a combination of these methods. As long as the transmission spectrum of the light absorber 10 at an incident angle of 0° satisfies the conditions (I) to (V), or the transmission spectrum of a plate-like body having a smooth surface and a thickness of 1 mm formed by curing the resin is 90% or more at wavelengths of 450 nm to 800 nm, the light absorber 10 can satisfy either of the conditions. Examples of the curable resin include cyclic polyolefin resins, epoxy resins, polyimide resins, modified acrylic resins, silicone resins, and polyvinyl resins (PVA) such as polyvinyl butyral (PVB).

[0072] The light absorber 10 and the light absorbing composition may contain a curing catalyst that promotes the curing of the curable resin. The curing catalyst can be a catalyst that can control conditions such as the curing speed of the curable resin, the curing reactivity of the resin, and the hardness of the cured resin.

[0073] The curing catalyst is preferably an organic compound containing a metal component. The organometallic compound is not limited to a specific compound. Examples of the organometallic compound include organoaluminum compounds, organotitanium compounds, organozirconium compounds, organozinc compounds, and organotin compounds.

[0074] The organoaluminum compound is not limited to a specific compound. Examples of the organoaluminum compound include aluminum salt compounds such as aluminum triacetate and aluminum octylate, aluminum alkoxide compounds such as aluminum trimethoxide, aluminum triethoxide, aluminum dimethoxide, aluminum diethoxide, aluminum triallyl oxide, aluminum diallyl oxide, and aluminum isopropoxide, and aluminum methoxybis(ethylacetoacetate), aluminum methoxybis(acetylacetonate), aluminum ethoxybis(ethylacetoacetate), aluminum ethoxybis(acetylacetonate), and aluminum isopropoxybis(ethylacetoacetate). Examples include aluminum chelate compounds such as aluminum isopropoxybis(methyl acetoacetate), aluminum isopropoxybis(t-butyl acetoacetate), aluminum butoxybis(ethyl acetoacetate), aluminum dimethoxy(ethyl acetoacetate), aluminum dimethoxy(acetylacetonate), aluminum diethoxy(ethyl acetoacetate), aluminum diethoxy(acetylacetonate), aluminum diisopropoxy(ethyl acetoacetate), aluminum diisopropoxy(methyl acetoacetate), aluminum tris(ethyl acetoacetate), and aluminum tris(acetylacetonate). These may be used alone or in combination.

[0075] The organic titanium compound is not limited to a specific compound. Examples of the organic titanium compound include titanium chelates such as titanium tetraacetylacetonate, dibutyloxytitanium diacetylacetonate, titanium ethylacetoacetate, titanium octylene glycolate, and titanium lactate, and titanium alkoxides such as tetraisopropyl titanate, tetrabutyl titanate, tetramethyl titanate, tetra(2-ethylhexyl titanate), titanium tetra-2-ethylhexoxide, titanium butoxy dimer, titanium tetra-normal butoxide, titanium tetraisopropoxide, and titanium diisopropoxybis(ethylacetoacetate). These compounds may be used alone or in combination.

[0076] The organic zirconium compound is not limited to a specific compound. Examples of the organic zirconium compound include zirconium chelates such as zirconium tetraacetylacetonate, zirconium dibutoxybis(ethylacetoacetate), zirconium monobutoxyacetylacetonate bis(ethylacetoacetate), zirconium tributoxymonoacetylacetonate, and zirconium tetraacetylacetonate, and zirconium alkoxides such as zirconium tetra-normal butoxide and zirconium tetra-normal propoxide. These may be used alone or in combination.

[0077] Examples of organic zinc compounds include zinc alkoxides such as dimethoxyzinc, diethoxyzinc, and ethylmethoxyzinc, which may be used alone or in combination.

[0078] Examples of organotin compounds include tin alkoxides such as dimethyltin oxide, diethyltin oxide, dipropyltin oxide, dibutyltin oxide, dipentyltin oxide, dihexyltin oxide, diheptyltin oxide, and dioctyltin oxide, which may be used alone or in combination.

[0079] The curing catalyst may further contain at least one of an alkoxide having a metal component and a hydrolyzate of an alkoxide having a metal component, as described above. The alkoxide having a metal component and the hydrolyzate of an alkoxide having a metal component are collectively referred to as a "metal alkoxide compound." The metal alkoxide is represented by the general formula M(OR) n (M is a metal element, n is an integer of 1 or greater), and is a compound in which the hydrogen atom of a hydroxy group of an alcohol is substituted with the metal element M. Metal alkoxides form M-OH upon hydrolysis and further form M-O-M bonds upon reaction with metal alkoxides of other molecules. For example, when a light-absorbing composition contains a compound such as a curable resin and the flowable light-absorbing composition is cured to form the light absorber 10, the metal alkoxide compound may function as a catalyst to promote curing of the light-absorbing composition. When the light-absorbing composition is cured by heat treatment, the higher the heat treatment temperature, the more likely it is that environmental resistance, such as heat resistance, will improve. On the other hand, high heat treatment temperatures may deteriorate the properties of some light-absorbing compounds or ultraviolet absorbers described below. Deterioration of the properties of the ultraviolet absorber may cause the wavelength of light absorbed by the ultraviolet absorber to deviate from the intended absorption wavelength. There is also a possibility that the absorption ability of the ultraviolet absorber may decrease or disappear. However, when the light absorber contains a metal alkoxide compound, curing of the light-absorbing composition can be promoted even without high heat treatment temperatures. As a result, the light absorber 10 tends to have high environmental resistance.

[0080] The metal component contained in the metal alkoxide compound is not limited to a specific component, and examples of the metal component include Al, Ti, Zr, Zn, Sn, and Fe. Examples of metal alkoxides include CAT-AC and DX-9740, which are aluminum alkoxides manufactured by Shin-Etsu Chemical Co., Ltd., ORGATIXX AL-3001, which is an aluminum alkoxide manufactured by Matsumoto Fine Chemical Co., Ltd., aluminum isopropoxide, which is an aluminum alkoxide manufactured by Tokyo Chemical Industry Co., Ltd., titanium alkoxides D-20, D-25, and DX-175 manufactured by Shin-Etsu Chemical Co., Ltd., titanium alkoxides ORGATIXX TA-8, TA-21, TA-30, TA-80, and TA-90 manufactured by Matsumoto Fine Chemical Co., Ltd., zirconia alkoxides D-15 and D-31 manufactured by Shin-Etsu Chemical Co., Ltd., and zirconia alkoxides ORGATIXX ZA-45 and ZA-65 manufactured by Matsumoto Fine Chemical Co., Ltd. can be used.

[0081] In the light absorber 10 and the light absorbing composition, the ratio γ of the content of the copper component to the content of the metal component contained in the metal alkoxide compound MC is not limited to a specific value. MC is, for example, 1 × 10 2 ~7 x 10 2 and preferably 2×10 2 ~6 x 10 2 and more preferably 3×10 2 ~5 x 10 2 is.

[0082] In the light absorber 10 and the light absorbing composition, the ratio γ of the content of the phosphorus component to the content of the metal component contained in the metal alkoxide compound MP is not limited to a specific value. MP , for example, 0.5×10 2 ~5 x 10 2 and preferably 1×10 2 ~4 x 10 2 and more preferably 1.5×10 2 ~3 x 10 2 is.

[0083] The light absorber 10 and the light-absorbing composition may contain an ultraviolet absorber that absorbs a portion of ultraviolet light. The ultraviolet absorber is not limited to a specific compound as long as the transmission spectrum of the light absorber 10 at an incident angle of 0° satisfies conditions (I) to (V). The ultraviolet absorber is, for example, a compound that does not have both a hydroxy group and a carbonyl group in its molecule, i.e., a compound that does not have both a hydroxy group and a carbonyl group in its molecule when represented by a structural formula. The curing of the light-absorbing composition can be promoted by, for example, the coordination of a reactant or precursor to a specific position in the molecule of an alkoxide or the like containing a metal component. For example, the presence of a group that is more likely to coordinate with a substance other than the substance used in the reaction for curing the light-absorbing composition may weaken the catalytic action. In particular, both hydroxy groups and carbonyl groups have high electron-donating properties, and when an alkoxide compound reacts or coordinates with a UV absorber containing these groups, some of them form a complex, which may change the UV absorption properties inherent to the UV absorber. However, when the ultraviolet absorber is a compound that does not have both a hydroxy group and a carbonyl group in the molecule, the alkoxide compound is unlikely to form a complex with the ultraviolet absorber, and the ultraviolet absorber's inherent ultraviolet absorbing properties are likely to be exhibited. Note that the ultraviolet absorber may contain only one of a hydroxy group and a carbonyl group in the molecule.

[0084] The ultraviolet absorber is preferably selected from the viewpoints of absorbing light in a desired wavelength range, being compatible with a specific solvent, dispersing well in a light-absorbing composition, particularly a curable resin, and having excellent environmental resistance. Examples of ultraviolet absorbers include benzophenone-based compounds, benzotriazole-based compounds, salicylic acid-based compounds, and triazine-based compounds. For example, Tinuvin PS, Tinuvin 99-2, Tinuvin 234, Tinuvin 326, Tinuvin 329, Tinuvin 900, Tinuvin 928, Tinuvin 405, and Tinuvin 460 can be used as ultraviolet absorbers. These are ultraviolet absorbers manufactured by BASF, and Tinuvin is a registered trademark.

[0085] The content of the ultraviolet absorber in the light absorber is not limited to a specific value as long as the transmission spectrum of the light absorber 10 at an incident angle of 0° satisfies conditions (I) to (V). High light absorption capacity can be achieved by including a small amount of ultraviolet absorber. The ratio of the content of the ultraviolet absorber to the content of the copper component in the light absorber 10 is, on a mass basis, for example, 0.01 to 1, preferably 0.02 to 0.5, and more preferably 0.07 to 0.14. The ratio of the content of the ultraviolet absorber to the content of the phosphorus component in the light absorber is, on a mass basis, for example, 0.02 to 2, preferably 0.04 to 1, and more preferably 0.12 to 0.26.

[0086] The light-absorbing dispersion contains at least a light-absorbing compound (light absorber) and a solvent. The light-absorbing dispersion may contain a dispersant that contributes to the dispersion of the light-absorbing compound. For example, a light-absorbing composition is obtained by adding an appropriate curable resin to the light-absorbing dispersion. For example, the light-absorbing composition is cured to produce the light absorber 10.

[0087] The light-absorbing dispersion may contain, for example, a solvent, a light-absorbing compound containing a phosphonic acid and a copper component, and a phosphate ester that contributes to the dispersion of the light-absorbing compound in the solvent. The light-absorbing dispersion is substantially free of a curable resin. Therefore, there is no concern that the dispersion will harden during distribution of the light-absorbing dispersion, and a person seeking to obtain the light absorber 10 can prepare a light-absorbing composition that is a precursor to the light absorber 10 by mixing the light-absorbing dispersion with a separately prepared curable resin. Reducing concerns about hardening or thickening of the material during product distribution can also contribute to extending the shelf life or pot life of the dispersion.

[0088] The term "light-absorbing dispersion substantially free of curable resin" means that the light-absorbing dispersion does not solidify even when external energy such as heating or irradiation with electromagnetic waves (including visible light and ultraviolet rays) is applied to the light-absorbing dispersion. The light-absorbing dispersion may contain a curable resin to the extent that it does not solidify. The type of energy applied to cure the curable resin mixed with the light-absorbing dispersion is not limited. Application of energy includes heating and irradiation with electromagnetic waves such as light. For example, curing by leaving (standing) at normal room temperature (20°C to 28°C) is also included in the application of energy as heating in a broad sense. The light-absorbing dispersion does not contain a curable resin, such as a curable epoxy resin, a phenolic resin, a melamine resin, an unsaturated polyester resin, an alkyd resin, a silicone resin, a polyurethane resin, a polyimide resin, an acrylic resin, a urea resin, or a modified product thereof. Curable acrylic resins include modified acrylate resins such as epoxy acrylate and urethane acrylate. Furthermore, when the light-absorbing dispersion is substantially free of a curable resin, at least curing does not occur. On the other hand, the curable resin may be supplied in two or more parts, such as a combination of the agent and a curing agent, or a combination of the agent and a catalyst. When considering the circumstances of such a set of curable resins, the light-absorbing dispersion liquid that is a specific example of the present invention includes a system that contains the agent but does not contain a curing agent or a catalyst.

[0089] The light-absorbing dispersion may contain a primary phosphonic acid and a secondary phosphonic acid. A light-absorbing compound containing an alkylphosphonic acid has high absorbency at wavelengths from 800 nm to 1200 nm in the near-infrared region, while a light-absorbing compound containing an arylphosphonic acid has high absorbency at wavelengths around 680 nm. In many cases, it is meaningful for the light-absorbing dispersion to contain both a primary phosphonic acid and a secondary phosphonic acid. In the light-absorbing dispersion, a light-absorbing compound containing an arylphosphonic acid and a copper component, and a light-absorbing compound containing an alkylphosphonic acid and a copper component may be contained in a solvent that does not contain the curable resin.

[0090] The solvent contained in the light-absorbing dispersion is not limited to a specific solvent. The solvent contained in the light-absorbing dispersion is, for example, an organic solvent. The solvent contained in the light-absorbing dispersion is not limited thereto, but may be tetrahydrofuran (THF), toluene, acetone, acetonitrile, acetylacetone, allyl alcohol, benzene, benzyl alcohol, butanol, methyl ethyl ketone, butyl alcohol, epichlorohydrin, cresol, methanol, ethanol, or a mixture of two or more organic solvents selected from these.

[0091] The light-absorbing dispersion liquid has, for example, a specific transmission spectrum. The light-absorbing dispersion liquid has, for example, a transmission spectrum that satisfies the following (i), (ii), (iii), and (iv). This transmission spectrum can be obtained, for example, by irradiating light having a wavelength of 300 nm to 1600 nm onto the light-absorbing dispersion liquid and normalizing the obtained transmission spectrum so that the transmittance at a wavelength of 700 nm is 20%. (i) The average value T of the transmittance in the wavelength range of 460 nm to 600 nm A DP(460-600) is 85% or more. (ii) The cutoff wavelength λ on the short wavelength side where the transmittance is 50% in the wavelength range of 350 nm to 450 nm H DP(S) (iii) The cutoff wavelength λ on the long wavelength side at which the transmittance is 50% in the wavelength range of 600 nm to 700 nm is 380 nm to 420 nm. H DP(L) (iv) The average value T of the transmittance in the wavelength range of 725 nm to 1000 nm A DP(725-1000) is 5% to 20%.

[0092] A dispersion of a light-absorbing compound is prepared, for example, by dispersing the light-absorbing compound in toluene at a predetermined concentration. The dispersion is then placed in a commercially available quartz cell to prepare a measurement workpiece. The transmission spectrum of the workpiece is measured using a spectrophotometer, and a baseline is subtracted to obtain the transmission spectrum of the dispersion of the light-absorbing compound. Furthermore, the transmittance is normalized over the measurement wavelength range so that the transmittance at a wavelength of 700 nm is 20%. The baseline can be determined, for example, by placing the transmission spectrum of toluene without the light-absorbing compound in the same quartz cell and measuring it using a spectrophotometer.

[0093] When the transmission spectrum of a dispersion of a light-absorbing compound satisfies the above conditions (i) to (iv), a light absorber produced by mixing this dispersion with various curable resins to obtain a light-absorbing composition and curing the composition, or an optical filter comprising the light absorber, is likely to satisfy the above conditions (I) to (V).

[0094] Short wavelength cutoff wavelength λ H DP(S) The long wavelength cutoff wavelength λ may be 390 nm to 410 nm. H DP(L) may be 610 nm to 640 nm, or may be 615 nm to 635 nm.

[0095] The transmission spectrum of the dispersion of the light-absorbing compound may satisfy the following conditions (v), (vi), (vii), and (viii): (v) a wavelength λ corresponding to a minimum value of transmittance in the wavelength range of 700 nm to 1500 nm; min DP(700-1500) is in the range of 750 nm to 950 nm. (vi) The difference λ between the longest and shortest wavelengths at which the transmittance is 20% in the wavelength range of 600 nm to 1500 nm. range(20) (vii) The difference λ between the longest and shortest wavelengths at which the transmittance is 50% in the wavelength range of 600 nm to 1500 nm. range(50)(viii) The difference λ between the longest and shortest wavelengths at which the transmittance is 50% in the wavelength range of 350 nm to 700 nm range(50) DP(350-700) is 180 nm to 280 nm.

[0096] When the transmission spectrum of a dispersion of a light-absorbing compound satisfies the above conditions (v) to (viii), a light absorber produced by mixing this dispersion with various binders to obtain a light-absorbing composition and curing the mixture, or an optical filter comprising the light absorber, is more likely to satisfy the above conditions (I) to (V).

[0097] wavelength λ min DP(700-1500) may be in the range of 800 nm to 900 nm, or in the range of 820 nm to 880 nm. range(20) DP(600-1500) may be 400 nm to 550 nm. range(50) DP(600-1500) may be 620 nm to 720 nm, or 630 nm to 710 nm. range(50) DP(350-700) may be 190 nm to 260 nm, or may be 200 nm to 250 nm.

[0098] In the optical filter 1a, the thickness of the light absorber 10 is not limited to a specific thickness. The thickness is, for example, about 200 nm or less, which contributes greatly to reducing the height of the device. On the other hand, the optical filter 1b including the substrate 20 tends to have high rigidity or mechanical strength, and can provide a rigid optical filter.

[0099] The substrate 20 is not limited to a specific substrate. For example, the substrate 20 may be selected so that the optical filter 1b satisfies the above conditions (I) to (V), or may be selected so that the optical filter 1b further satisfies the above conditions (VI) and (VII). The substrate 20 may be selected so that the optical filter 1b satisfies the above conditions (1-i) to (1-iv) and conditions (2-i) to (2-iv).

[0100] The shape of the substrate 20 is not limited to a specific shape. As shown in FIG. 1B, the substrate may be flat. In this case, when the substrate 20 is used as a support for the optical filter 1b, it is easy to apply a light-absorbing composition, and the substrate 20 is considered to have high versatility as an optical filter. On the other hand, the substrate 20 may include a curved surface and may have a convex or concave surface. The substrate 20 may have a shape other than a plate. For example, examples of the substrate 20 include optical elements such as lenses, polarizers, prisms, reflective elements, and diffraction gratings. These optical elements may have surfaces that include curved and flat surfaces. Further examples of the substrate 20 include photoelectric conversion elements such as photodiodes and phototransistors, image sensors in which a large number of photoelectric conversion elements such as CCDs or CMOSs ​​are arranged, or image sensors equivalent to such image sensors, and even microlens arrays integrated with image sensors. Yet another example of the substrate 20 is a display device such as a display of a portable information terminal.

[0101] The substrate 20 may be transparent. When the substrate 20 is transparent, the transmission spectrum of the light absorber 10 is likely to be reflected in the transmission spectrum of the optical filter 1b including the light absorber 10 and the substrate 20. In the transmission spectrum of a 3 mm thick flat plate made of the same material as the substrate 20, the transmittance may be 90% or more in the wavelength range of 360 nm to 900 nm, and 85% or more in the wavelength range of 350 nm to 1200 nm. A typical example of the substrate 20 having such transparency is a glass substrate. The substrate 20 may be silicate glass such as soda-lime glass or borosilicate glass, or phosphate glass or fluorophosphate glass containing coloring components such as Cu and Co. Phosphate glass and fluorophosphate glass containing coloring components are, for example, infrared-absorbing glasses and are themselves light-absorbing. When a light absorber is used together with a substrate of infrared absorbing glass, the light absorption and transmission spectrum of both can be adjusted to produce an optical filter having desired optical characteristics, allowing for a high degree of freedom in designing optical filters.

[0102] A typical example of the substrate 20 is a resin substrate. The resin contained in the resin substrate is a cycloolefin resin such as a norbornene resin, a polyarylate resin, an acrylic resin, a modified acrylic resin, a polyimide resin, a polyetherimide resin, a polyolefin resin, a polysulfone resin, a polyethersulfone resin, a polycarbonate resin, or a silicone resin. Resins are significantly more processable and moldable than glass. This makes it easy to prepare substrates of various shapes, such as for optical elements.

[0103] An anti-reflection film or a reflection-reducing film may be provided on the surface of the light absorber 10 or an optical filter including the light absorber 10 in order to reduce reflectance or increase transmittance of light of a predetermined wavelength. Each of Figures 1C to 1D shows an example of an optical filter including the light absorber 10 and an anti-reflection film.

[0104] 1C, an antireflection film 31a is disposed on one main surface of the light absorber 10, and an antireflection film 32a is disposed on the other main surface. Each of the antireflection films 31a and 32a has a single-layer structure.

[0105] 1D, an antireflection film 31b is disposed on one main surface of the light absorber 10, and an antireflection film 32b is disposed on the other main surface. Each of the antireflection films 31b and 32b has a two-layer structure.

[0106] 1E, an antireflection film 31c is disposed on one main surface of the light absorber 10, and an antireflection film 32c is disposed on the other main surface. Each of the antireflection films 31c and 32c has a three-layer structure.

[0107] 1F, an antireflection film 31d is disposed on one main surface of the light absorber 10, and an antireflection film 32d is disposed on the other main surface. Each of the antireflection films 31d and 32d is an antireflection film with a multilayer structure having three or more layers.

[0108] When the optical filter includes a transparent substrate and a light absorber 10 formed on the transparent substrate, an anti-reflection film may be formed on the surface of the light absorber 10 and on the surface of the transparent substrate that is not in contact with the light absorber 10.

[0109] The antireflection film can increase the transmittance of the light absorber 10 or an optical filter in a transmission wavelength band, which is a wavelength band of light that can transmit the light absorber 10 or an optical filter including the light absorber 10. The transmission wavelength band may be a wavelength band in which the transmittance is 50% or more in the transmission spectrum of the light absorber 10 or an optical filter including the light absorber 10.

[0110] When an antireflection film is formed on the light absorber 10, an optical filter including the light absorber 10, or a transparent substrate for supporting them (for example, Corning D263T eco), the reflectance at wavelengths of 400 nm to 600 nm when light with a wavelength of 300 nm to 1200 nm is incident at an incident angle of 5° is, for example, 1% or less, preferably 0.5% or less, and more preferably 0.25% or less.

[0111] When an antireflection film is formed on the light absorber 10, an optical filter including the light absorber 10, or a transparent substrate for supporting them, the average value of the reflectance at wavelengths of 700 nm to 1200 nm when light with a wavelength of 300 nm to 1200 nm is incident at an incident angle of 5° is, for example, 1% or less, preferably 0.5% or less, and more preferably 0.25% or less. This makes it less likely that a part of the light belonging to the infrared range will be reflected, resulting in ghosts or flares in the obtained image.

[0112] In an optical filter including the light absorber 10 and an anti-reflection film, when light having a wavelength of 300 nm to 1200 nm is incident at an incident angle of 50°, the reflectance at wavelengths of 400 nm to 600 nm is, for example, 3% or less, preferably 1% or less. In addition, when light having a wavelength of 300 nm to 1200 nm is incident at an incident angle of 50° in the optical filter, the average value of the reflectance at wavelengths of 700 nm to 1200 nm is, for example, 3% or less, preferably 1.5% or less. This makes it easy to prevent reflection of light even when the incident angle to the light absorber 10 or an optical filter including the light absorber 10 becomes large.

[0113] The anti-reflection film is not limited to a specific film. The anti-reflection film includes, for example, at least one layer selected from the group consisting of the following (a), (b), and (c). The anti-reflection film may include a combination of two or more types of layers: (a) a layer formed by a sol-gel method using a silicon-containing reactive material; (b) a layer formed by a sol-gel method using a silicon-containing reactive material, and further including fine particles; (c) a layer formed by a physical film formation method such as vacuum deposition or sputtering.

[0114] Regarding the above layers (a) and (b), the silicon-containing reactive material is not limited to a specific material, and the functional group contained in the reactive material is not limited to a specific functional group. The silicon-containing reactive material preferably includes a trifunctional silane such as methyltriethoxysilane (MTES) and a tetrafunctional silane such as tetraethoxysilane (TEOS). Tetrafunctional silanes are important for forming coatings with a strong and dense skeleton. On the other hand, using tetrafunctional silanes alone can cause problems such as difficulty in controlling reactivity, poor polarity selectivity, and easy cracking. Using a trifunctional silane in addition to a tetrafunctional silane improves the flexibility of the silica skeleton and improves polarity selectivity. This enables the adjustment of the refractive index (polarity adjustment) required for the anti-reflective coating. Additionally, cracking is also easily suppressed. The organic functional group attached to the trifunctional silane is not particularly limited. Preferably, a trifunctional silane having a methyl group is used in combination with a tetrafunctional silane. This is because a homogeneous liquid and coating film can be easily formed. The amounts of trifunctional silane and tetrafunctional silane are preferably in the range of trifunctional silane:tetrafunctional silane = 5:1 to 1:3. This allows the trifunctional silane to suppress the occurrence of cracks in the anti-reflective coating, while the tetrafunctional silane can form a strong skeleton. The silicon-containing reactive material may include a bifunctional silane. The raw materials for the layer (a) may include components other than those involved in the sol-gel process.

[0115] The trifunctional silane is not limited to a specific silane. Examples of trifunctional silanes include methyltriethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, ethyltrimethoxysilane, propyltriethoxysilane, propyltrimethoxysilane, butyltriethoxysilane, butyltrimethoxysilane, pentyltrimethoxysilane, pentyltriethoxysilane, hexyltriethoxysilane, and hexyltrimethoxysilane, and may also be trifunctional silanes having an alkyl group directly bonded to a silicon atom (Si). The tetrafunctional silane is not limited to a specific silane. Examples of tetrafunctional silanes include tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0116] Each silane compound produces a hydrolyzate of a silane compound containing a silanol group upon hydrolysis, and the trifunctional silane is converted to (poly)silsesquioxane, and the tetrafunctional silane is converted to silica by condensation polymerization of the hydrolyzate. Since the refractive index of (poly)silsesquioxane and silica is low, at approximately 1.46, it is possible to form a layer having a low refractive index. Therefore, a layer containing at least one selected from the group consisting of (poly)silsesquioxane and silica is suitable as a layer to be included in the antireflection film of the light absorber 10 or an optical filter equipped with the light absorber 10.

[0117] In forming the layers (a) and (b), for example, a coating film of a liquid composition containing a silicon-containing reactive material may be formed and then baked. The baking of the coating film may be carried out, for example, at a temperature in the range of 60°C to 170°C, preferably 60°C to 150°C, and more preferably 60°C to 115°C.

[0118] Regarding the layer (b) above, a layer containing a silicon-containing reactive material, a hydrolyzate of that reactive material, or a polycondensate of that hydrolyzate may contain a particulate compound. Such particulate compounds are, for example, fine particles containing silica, titania, zirconia, or alumina. The refractive index of the material forming the fine particles is, for example, 1.40 to 2.55. The material constituting the fine particles is preferably silica. In a layer containing at least one selected from the group consisting of silica and (poly)silsesquioxane, these act as a binder surrounding the fine particles. Therefore, the bonding strength between the fine particles and the binder is strengthened via silanol groups, etc., and improved reliability, such as weather resistance, can be expected.

[0119] The fine particles contained in the layer (b) may be hollow fine particles. Since hollow fine particles have an empty space inside, their refractive index tends to be very low. The refractive index of hollow fine particles is, for example, 1.02 to 1.50.

[0120] The average particle diameter of the hollow fine particles is, for example, 5 nm to 200 nm. The average particle diameter of the hollow fine particles can be determined, for example, by measuring the maximum diameters of 50 or more randomly selected particles in the cross section of the layer (b) using a microscope such as an optical microscope, an electron microscope, or a metallurgical microscope, and then calculating the arithmetic average of the maximum diameters.

[0121] The content of the hollow fine particles in the layer (b) is, for example, 5 to 95% by mass.

[0122] When the layer (b) contains hollow fine particles, the refractive index of the layer tends to be very low. When the layer (b) contains hollow fine particles, the refractive index of the layer (b) is, for example, 1.00 to 1.45 (excluding 1.00). For example, Sururia 4110 manufactured by JGC Catalysts and Chemicals, Ltd. can be used as the hollow fine particles.

[0123] In a layer containing at least one selected from the group consisting of silica and (poly)silsesquioxane, when hollow particles are included and when no hollow particles are included, the refractive index of the layer tends to be lower when hollow particles are included. The antireflection film may be configured so that a layer containing at least one selected from the group consisting of silica and (poly)silsesquioxane and hollow particles, a layer containing at least one selected from the group consisting of silica and (poly)silsesquioxane but not hollow particles, and a light absorber 10 or an optical filter equipped with a light absorber 10 are arranged in this order. In this case, an improved antireflection effect may be expected.

[0124] The fine particles contained in the layer (b) may be solid fine particles. The refractive index of the solid fine particles is, for example, 1.25 to 1.65, more preferably 1.30 to 1.65. When the layer (b) contains solid fine particles, the refractive index of the layer (b) is, for example, 1.10 to 1.55. The average particle diameter of the solid fine particles is, for example, 2 nm to 200 nm. The average particle diameter of the solid fine particles can be determined, for example, in the same manner as the average particle diameter of hollow fine particles. For example, Snowtex MP-2040 manufactured by Nissan Chemical Industries, Ltd. can be used as the solid fine particles.

[0125] The (b) layer may contain fine particles with a relatively high refractive index. This facilitates the (b) layer's high refractive index. In this case, the fine particles may contain at least one material selected from the group consisting of TiO2 (titanium oxide, refractive index 2.33-2.55), Ta2O5 (tantalum oxide, refractive index 2.16), Nb2O5 (niobium oxide, refractive index 2.33), and Si3N4 (silicon nitride, refractive index 2.02). The fine particles may contain two or more materials. The (b) layer preferably contains fine particles such as TiO2. In this case, the refractive index of the (b) layer is likely to be high, resulting in a high-refractive-index film, in contrast to a low-refractive-index film containing, for example, hollow silica (SiO2) particles. When the (b) layer contains TiO2 fine particles, the refractive index of this layer is, for example, 1.50-2.30. For example, the refractive index of the (b) layer can be controlled by adjusting the content of the fine particles relative to the amount of the film components.

[0126] The average particle diameter of the TiO2 fine particles is, for example, 2 nm to 200 nm. The average particle diameter of the TiO2 fine particles can be determined, for example, in the same manner as the average particle diameter of hollow fine particles. The content of the TiO2 fine particles in layer (b) is, for example, 2% to 50% by mass. As the TiO2 fine particles, for example, NS405 manufactured by Teika Corporation or TTO-51A manufactured by Ishihara Sangyo Kaisha, Ltd. can be used.

[0127] The particles contained in the layer (b) may be surface-treated with a coupling agent such as a silane coupling agent or a titanium coupling agent before being mixed with the binder or matrix. This improves the adhesion or wettability between the binder or matrix and the particles. This surface treatment is also effective when particles other than TiO2 and SiO2 are used.

[0128] For example, the antireflection film may be configured by combining a low-refractive index layer, a medium-refractive index layer, and a high-refractive index layer. The low-refractive index layer is, for example, a layer containing at least one selected from the group consisting of silica and (poly)silsesquioxane and hollow fine particles. The medium-refractive index layer is, for example, a layer containing at least one selected from the group consisting of silica and (poly)silsesquioxane and not containing hollow fine particles. The high-refractive index layer is, for example, a layer containing at least one selected from the group consisting of silica and (poly)silsesquioxane and TiO fine particles. When combining a low-refractive index layer, a medium-refractive index layer, and a high-refractive index layer in the antireflection film, the antireflection film may be configured by taking into consideration conditions such as the thickness of each layer, the number of each layer, and the repeating pattern of these layers.

[0129] The (c) layer can be formed by physical methods such as vacuum deposition, including ion-assisted deposition (IAD), sputtering, and ion plating. These methods are collectively called deposition methods. By using deposition methods, a layer containing a dielectric and a metal oxide can be obtained as the (c) layer. The material of the (c) layer formed by deposition methods is not limited to a specific material. Examples of materials for the (c) layer include SiO2, TiO2, Ta2O3, SnO2, In2O3, Nb2O5, Si3N4, and TiN. x and MgF2. The layer (c) may be a layer in which two or more inorganic compounds selected from these inorganic compounds are mixed in a predetermined ratio.

[0130] The layer (c) may have a single layer structure made of only the same material, or may have a multilayer structure in which two or more layers made of different materials (which may be a mixture of materials) selected from the inorganic compounds described above are laminated. When the antireflection coating is a multilayer coating, the antireflection coating may be formed by alternately laminating layers made of materials having a relatively high refractive index, such as TiO2, Ta2O3, and Nb2O5, or a mixture of these materials, and layers made of materials having a relatively low refractive index, such as SiO2 and MgF2, or a mixture of these materials, while adjusting the thickness of these layers and the number of times they are laminated.

[0131] The optical filter including the light absorber 10 may be used in an ambient light sensor. An ambient light sensor is a device that is mounted on an apparatus and detects the brightness or hue of the surroundings of the apparatus. The ambient light sensor recognizes the attributes of the light around the apparatus and automatically adjusts, for example, the brightness of a display device such as a display mounted on the apparatus. The ambient light sensor is also sometimes called a luminance sensor or an illuminance sensor.

[0132] FIG. 2A is a cross-sectional view showing an example of an ambient light sensor. As shown in FIG. 2A , the ambient light sensor 2 includes, for example, an electric circuit board 3, a photoelectric conversion element 4, a housing 5, and an optical filter 1a. The ambient light sensor 2 detects, for example, attributes of light in the visible light range among attributes of light around a device including the ambient light sensor 2. The electric circuit board 3 supports the ambient light sensor 2 and electrically connects the ambient light sensor 2 to peripheral devices. The photoelectric conversion element 4 is disposed on the electric circuit board 3 and includes, for example, an element such as a photodiode or a phototransistor. The housing 5 is disposed on the electric circuit board 3 and surrounds the periphery of the photoelectric conversion element 4. The optical filter 1a is disposed, for example, in front of the photoelectric conversion element 4 and blocks a portion of light traveling toward the photoelectric conversion element 4. The optical filter 1a blocks, for example, a portion of light belonging to ultraviolet or infrared rays. The optical filter 1a is supported by the housing 5.

[0133] The ambient light sensor may include an optical filter including a light absorber 10 as shown in FIG. 2A , or may include an integrated photoelectric conversion element in which the light absorber 10 and a photoelectric conversion element are integrated as shown in FIG. 2B . The photoelectric conversion element 2b shown in FIG. 2B includes a light receiving surface 2f and a light absorber 10. In the photoelectric conversion element 2b, the light receiving surface 2f and the light absorber 10 are arranged in this order. The photoelectric conversion element 2b is an integrated photoelectric conversion element. The integrated photoelectric conversion element can be obtained, for example, by applying the above-mentioned light-absorbing composition to the surface of the light receiving surface (window) of the photoelectric conversion element and curing it to form the light absorber 10. When such a photoelectric conversion element is used, there is no need to use a light absorber separately from the photoelectric conversion element. Such an ambient light sensor can block some light outside the visible light range, such as ultraviolet or infrared light, by absorption in the light absorber 10, significantly improving the ease of use of the ambient light sensor as an ambient light sensor specialized for detecting light in the approximately visible light range. In addition, simplification of the supply chain for product distribution can also be expected.

[0134] In the photoelectric conversion element 2b, for example, a first electrode E1 and a photoelectric conversion layer L are stacked in this order on an electric circuit board 3. In addition, a second electrode E2, a light receiving surface 2f, and a light absorber 10 are disposed on the photoelectric conversion layer L.

[0135] An anti-reflection film or a reflection reduction film may be provided on the surface of the light absorber 10 or the optical filter including the light absorber 10 mounted on the ambient light sensor in order to reduce reflectance and increase transmittance of light of a specified wavelength.

[0136] The optical filter including the light absorber 10 may be used in an imaging device or a camera module. The imaging device or camera module includes, for example, an image sensor, an electric circuit board, a lens system, and an optical filter including the light absorber 10. In the image sensor, for example, a large number of photoelectric conversion elements such as CCD or CMOS are arranged. The electric circuit board electrically connects the image sensor to an external device. The lens system includes one or more lens groups for collecting light from a subject or the like onto the image sensor to form an image. The optical filter including the light absorber 10 can block some light belonging to ultraviolet and infrared rays.

[0137] For example, in an imaging device equipped with an optical filter including the light absorber 10, some ultraviolet and infrared light is blocked by absorption, while light in the visible light range passes through the optical filter toward the image sensor. If the optical filter has the function of reflecting some light using a dielectric multilayer film or the like, some of the light reflected by the optical filter may be reflected inside the housing or on the surface of a lens system located in front of the optical filter, or some of the reflected light may project onto the aperture or its shape and reach the light receiving surface of the imaging element, resulting in phenomena that degrade contrast, such as ghosts and flares. On the other hand, with an imaging device equipped with an optical filter including the light absorber 10, such phenomena are less likely to occur, and ghosts, flares, etc. are less noticeable in the captured image.

[0138] FIG. 3A is a diagram showing an example of an imaging device. This diagram shows an outline of the imaging device, and only elements necessary for explanation are schematically depicted, with other parts or elements omitted. As shown in FIG. 3A , an imaging device 6a includes an image sensor 7, a lens system 8, and an optical filter 1a. In the imaging device 6a, the optical filter 1a is disposed, for example, between the image sensor 7 and the lens system 8 and immediately before the image sensor 7. The arrangement of the optical filter is not limited to the arrangement shown in FIG. 3A . The optical filter may be disposed on the subject side, in front of the lens system 8. In this case, the optical filter includes, for example, a light absorber 10 and a transparent dielectric substrate that supports the light absorber 10. If a rigid substrate such as a glass substrate is used as the transparent dielectric substrate, the optical filter can be expected to function as a protective filter that protects the imaging device and the lens system from the outside.

[0139] FIG. 3B is a diagram showing another example of an imaging device. The imaging device 6b is configured similarly to the imaging device 6a, except for portions not particularly described. As shown in FIG. 3B , in the imaging device 6a, a light absorber 10 is disposed on the surface of some of the lenses 8a included in the lens system 8. For example, the above-described light-absorbing composition can be applied to the surface of the lens 8a and cured, and the light absorber 10 can be disposed so as to form an interface with the lens 8a. This allows the lens system 8 to have the desired light-blocking properties without providing a light-absorbing optical filter separately from the lens system 8, thereby significantly simplifying the assembly or manufacturing of the imaging device. Lenses 8a integrally formed with such light absorbers 10, or lens systems including such lenses 8a, may be distributed. An anti-reflection or reflection-reducing film may be formed on the surface of the light absorber 10. This reduces reflected light from the surface of the light absorber 10, making it easier to increase transmitted light in the visible light range. In the imaging device 6b, the arrangement of the light absorbers 10 is not limited to the arrangement shown in FIG. 3B .

[0140] The lens system of an imaging device may include a group of lenses formed by bonding the surfaces of two or more lenses together. An adhesive or a curable resin may be used to bond the lenses together. Although not shown, the above-described light-absorbing composition, the above-described light-absorbing dispersion, or the above-described light-absorbing compound may be included in an adhesive or the like used to bond the lenses together. In this case, the light absorber 10 is less susceptible to the external environment of the lens system, and protection of the light absorber 10 or components contained in the light absorber 10 is expected. When a curable resin is selected so that the refractive indexes of the light absorber 10 and the lens are approximately the same, reflection at the interface between the light absorber 10 and the lens can be significantly reduced, resulting in the advantage of eliminating the need for an anti-reflection coating.

[0141] The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0142] Example 1: 4.500 g of copper acetate monohydrate and 240 g of tetrahydrofuran (THF) were mixed and stirred for 3 hours to obtain a copper acetate solution. Next, 1.77 g of Plysurf A208N (Dai-ichi Kogyo Seiyaku Co., Ltd.), a phosphate ester compound, was added to the obtained copper acetate solution and stirred for 30 minutes to obtain Solution A. 40 g of THF was added to 0.552 g of phenylphosphonic acid and stirred for 30 minutes to obtain Solution B. 40 g of THF was added to 3.308 g of 4-bromophenylphosphonic acid and stirred for 30 minutes to obtain Solution C. 40 g of THF was added to 0.588 g of n-butylphosphonic acid and stirred for 30 minutes to obtain Solution D. To the mixture obtained by mixing Solution A, Solution B, Solution C, and Solution D, 6.68 g of methyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13) and 2.19 g of tetraethoxysilane (manufactured by Kishida Chemical Co., Ltd., special grade) were further added, and the mixture was stirred for 1 minute to obtain Solution E. Next, 120 g of toluene was added to Solution E, and the mixture was stirred for 1 minute at room temperature to obtain Solution F. Solution F was placed in a flask and heated in an oil bath (manufactured by Tokyo Rikakikai Co., Ltd., model: OSB-2100), while a solvent removal treatment was carried out using a rotary evaporator (manufactured by Tokyo Rikakikai Co., Ltd., model: N-1110SF). The set temperature of the oil bath was adjusted to 105°C. Thereafter, the liquid after the solvent removal treatment was removed from the flask. In this way, a dispersion liquid (Solution G) of the light-absorbing compound according to Example 1 containing phosphonic acid and a copper component was obtained.

[0143] Table 1 shows the raw materials and the amounts of raw materials added in preparing the light-absorbing compound and the dispersion of the light-absorbing compound according to Example 1. Table 2 shows the content ratios of the phosphonic acid, copper component, and phosphate ester contained in the dispersion of the light-absorbing compound, based on the amount of substance or by mass. It should be noted that the dispersion of the light-absorbing compound according to Example 1 contains the light-absorbing compound to be contained in the light absorber, but does not contain a curable resin or a curing catalyst.

[0144] 8.98 g of silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300), 0.16 g of catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., product name: CAT-AC), 6.96 g of methyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13) as a trifunctional alkoxysilane, 4.05 g of tetraethoxysilane (manufactured by Kishida Chemical Co., Ltd., special grade) as a tetrafunctional alkoxysilane, and 4.07 g of dimethyldiethoxysilane (DMDES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-22) as a bifunctional alkoxysilane were mixed and stirred for 30 minutes to obtain a liquid curable resin (H liquid) that acts as a binder or matrix resin.

[0145] Next, the liquid G, which is a dispersion liquid of the light-absorbing compound, and the liquid H, which is a curable resin, were mixed and stirred for 30 minutes to obtain the light-absorbing composition of Example 1. Table 1 shows the raw materials of the curable resin, curing catalyst, and alkoxysilane used in producing the light-absorbing composition of Example 1, and the amounts added thereof.

[0146] 0.1 g of a surface antifouling coating agent (manufactured by Daikin Industries, Ltd., product name: Optool DSX, active ingredient concentration: 20% by mass) and 19.9 g of a hydrofluoroether-containing liquid (manufactured by 3M, product name: Novec 7100) were mixed and stirred for 5 minutes to prepare a fluorine treatment agent (active ingredient concentration: 0.1% by mass). This fluorine treatment agent was applied to one main surface of a borosilicate glass substrate (manufactured by SCHOTT, product name: D263 T eco) measuring 130 mm x 100 mm x 0.70 mm. The glass substrate was then left at room temperature for 24 hours to dry the coating of the fluorine treatment agent. The glass surface was then lightly wiped with a dust-free cloth containing Novec 7100 to remove excess fluorine treatment agent. In this manner, a fluorine-treated substrate was prepared.

[0147] The light-absorbing composition according to Example 1 was applied to an 80 mm x 80 mm area in the center of one main surface of a fluorine-treated substrate using a dispenser to form a coating film. The resulting coating film was thoroughly dried at room temperature and then placed in an oven and heated sufficiently within a range of room temperature to 85°C to fully promote the reaction of the alkoxysilane and volatilize the contained solvent. The coating film was then left to stand for an additional 24 hours in an environment at a temperature of 85°C and a relative humidity of 85% to perform post-cure and complete the reaction. Finally, the coating film was peeled off from the fluorine-treated substrate to obtain a light absorber according to Example 1. When used to exert its function alone, this light absorber can be used as an optical filter.

[0148] (Measurement of Transmission Spectrum and Reflection Spectrum of Light Absorber) Using an ultraviolet-visible-near-infrared spectrophotometer V-770 equipped with a transmitted light measurement attachment manufactured by JASCO Corporation, the transmission spectrum of the light absorber according to Example 1 was measured at incident angles of 0°, 40°, 50°, 60°, and 70°. Unless otherwise specified, the measurement of the transmission spectrum was carried out with the temperature of the environment surrounding the measurement subject set to 22 to 25°C. Furthermore, in the ultraviolet-visible-near-infrared spectrophotometer V-770, the attachment was replaced with an attachment for measuring reflected light, and the reflection spectrum of the light absorber according to Example 1 was measured at incident angles of 5°, 40°, 50°, 60°, and 70°. Unless otherwise specified, the measurement of the transmission spectrum was carried out with the temperature of the environment surrounding the measurement subject set to 22 to 25°C.

[0149] Fig. 5A shows the transmission spectrum at each incident angle of the light absorber according to Example 1. Fig. 5B shows the reflection spectrum at each incident angle of the light absorber according to Example 1. Table 3 shows the characteristics corresponding to the above conditions (I) to (VII) of the light absorber according to Example 1 at an incident angle of 0° or an incident angle of 5°. Tables 4 and 5 show predetermined characteristics at each incident angle.

[0150] (Measurement of Transmission Spectrum of Dispersion of Light-Absorbing Compound) An appropriate amount of toluene was added to the dispersion of the light-absorbing compound according to Example 1 (Liquid G) to prepare a dispersion of the light-absorbing compound for measuring optical properties. The concentration of the light-absorbing compound in the dispersion of the light-absorbing compound for measuring optical properties was adjusted so that the transmittance at a wavelength of 700 nm was approximately 20% in the transmission spectrum of the dispersion of the light-absorbing compound. The dispersion of the light-absorbing compound for measuring optical properties thus prepared was placed in a quartz cell (manufactured by JASCO Corporation, model number: J / 1 / Q / 1, optical path length: 1 mm, optical path width: 10 mm, external dimensions: length 3.5 mm, width 12.5 mm, height 45 mm, capacity: 0.400 ml). The primary transmission spectrum of the dispersion of the light-absorbing compound according to Example 1 at an incident angle of 0° was measured using a UV-Visible-Near-Infrared Spectrophotometer V-770 manufactured by JASCO Corporation, equipped with a transmitted light measurement attachment capable of mounting a quartz cell. The measurement of the transmission spectrum was carried out with the temperature of the environment surrounding the measurement object set to 22 to 25° C. unless otherwise specified.

[0151] Furthermore, a transmission spectrum at an incident angle of 0° was similarly measured for a quartz cell filled with only toluene. The transmission spectrum of toluene was subtracted from the transmission spectrum of the dispersion of the light-absorbing compound to calculate a secondary transmission spectrum of the dispersion of the light-absorbing compound according to Example 1. Next, the obtained transmission spectrum was normalized so that the transmittance at a wavelength of 700 nm was 20%, thereby obtaining the final transmission spectrum of the dispersion of the light-absorbing compound. Note that the measurement for obtaining the transmission spectrum of the dispersion was carried out in the wavelength range of 300 nm to 1600 nm.

[0152] 5C shows the transmission spectrum of the dispersion of the light absorbing compound according to Example 1. Table 6 shows the characteristic values ​​determined from the transmission spectrum of the dispersion of the light absorbing compound.

[0153] (Haze Measurement) Using a haze meter (manufactured by Murakami Color Research Laboratory Co., Ltd., product name: HM-65L2), the haze of the light absorber according to Example 1 was measured in accordance with Japanese Industrial Standards (JIS) K 7136: 2000. Table 3 shows the haze value (0.13%) of the light absorber according to Example 1.

[0154] (Thickness Measurement) Using a laser displacement meter LK-H008 manufactured by Keyence Corporation, the thickness of the light absorber according to Example 1 was measured. Table 3 shows the thickness (192 μm) of the light absorber according to Example 1.

[0155] Example 2: 4.500 g of copper acetate monohydrate and 240 g of tetrahydrofuran (THF) were mixed and stirred for 3 hours to obtain a copper acetate solution. Next, 1.73 g of Plysurf A208N (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), a phosphate ester compound, was added to the obtained copper acetate solution and stirred for 30 minutes to obtain Solution A. 40 g of THF was added to 0.572 g of phenylphosphonic acid and stirred for 30 minutes to obtain Solution B. 40 g of THF was added to 3.431 g of 4-bromophenylphosphonic acid and stirred for 30 minutes to obtain Solution C. 40 g of THF was added to 0.410 g of ethylphosphonic acid and stirred for 30 minutes to obtain Solution D. To the mixed solution obtained by mixing Solution A, Solution B, Solution C, and Solution D, 6.93 g of methyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13) and 2.27 g of tetraethoxysilane (manufactured by Kishida Chemical Co., Ltd., special grade) were added, and the mixture was stirred for another 1 minute to obtain Solution E. Next, 120 g of toluene was added to Solution E, and the mixture was stirred at room temperature for 1 minute to obtain Solution F. Solution F was placed in a flask and heated in an oil bath (manufactured by Tokyo Rikakikai Co., Ltd., model: OSB-2100), while a solvent removal treatment was carried out using a rotary evaporator (manufactured by Tokyo Rikakikai Co., Ltd., model: N-1110SF). The set temperature of the oil bath was adjusted to 105°C. Thereafter, the liquid after the solvent removal treatment was removed from the flask. In this way, the light-absorbing compound of Example 2 containing a phosphonic acid and a copper component, and a dispersion of the light-absorbing compound of Example 2 (Liquid G) were obtained.

[0156] Table 1 shows the raw materials and the amounts of the raw materials added in preparing the light-absorbing compound according to Example 2 and the dispersion of the light-absorbing compound according to Example 2. Table 2 shows the content ratios of the phosphonic acid, copper component, and phosphate ester contained in the dispersion of the light-absorbing compound on a substance amount basis or mass basis. It should be noted here that the dispersion of the light-absorbing compound according to Example 2 contains the light-absorbing compound to be contained in the light absorber, but does not contain a curable resin or a curing catalyst.

[0157] 8.98 g of silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300), 0.16 g of catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., product name: CAT-AC), 6.96 g of methyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13) as a trifunctional alkoxysilane, 4.05 g of tetraethoxysilane (manufactured by Kishida Chemical Co., Ltd., special grade) as a tetrafunctional alkoxysilane, and 4.07 g of dimethyldiethoxysilane (DMDES) as a bifunctional alkoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-22) were mixed and stirred for 30 minutes to obtain a liquid curable resin H according to Example 2, which acts as a binder or matrix resin. Next, the G liquid according to Example 2, which is a dispersion containing a light-absorbing compound, and the curable resin H liquid were mixed and stirred for 30 minutes to obtain a light-absorbing composition according to Example 2.

[0158] Table 1 shows the curable resin (matrix or binder), curing catalyst, and alkoxysilane raw materials and the amounts of the raw materials added in the preparation of the light-absorbing composition according to Example 2.

[0159] The light-absorbing composition I according to Example 2 was applied using a dispenser to an 80 mm x 80 mm area in the center of one main surface of borosilicate glass (manufactured by SCHOTT, product name: D263 T eco) having dimensions of 130 mm x 100 mm x 0.70 mm, forming a coating film. The resulting coating film was thoroughly dried at room temperature and then placed in an oven and heated sufficiently between room temperature and 85°C to fully promote the reaction of the alkoxysilane and volatilize the contained solvent. The composition was then left to stand for an additional 24 hours in an environment at a temperature of 85°C and a relative humidity of 85% to perform post-cure and complete the reaction. The light absorber according to Example 2 was integrated onto the main surface of the transparent glass. The light absorber according to Example 2 formed on a glass substrate can be used as an optical filter when used to perform its function alone.

[0160] The transmission spectrum, reflection spectrum, haze value, and thickness of the light absorber formed on the glass substrate according to Example 2, and the transmission spectrum of the dispersion of the light absorbing compound according to Example 2 were measured in the same manner as in Example 1. In Example 2, the transmission spectrum, reflection spectrum, and haze value of the light absorber were measured for a laminate of the glass substrate and the light absorber.

[0161] 6 shows the transmission spectrum at each incident angle of the light absorber formed on the glass substrate according to Example 2. Table 3 shows the characteristics corresponding to the above conditions (I) to (VII) of the light absorber formed on the glass substrate according to Example 2 at an incident angle of 0° or an incident angle of 5°. Tables 4 and 5 show predetermined characteristics at each incident angle of the light absorber formed on the glass substrate according to Example 2. Table 3 shows the haze value (0.13%) of the light absorber formed on the glass substrate according to Example 2 and the thickness (182 μm) of the light absorber according to Example 2.

[0162] Example 3 A light-absorbing compound, a dispersion of the light-absorbing compound, a light-absorbing composition, and a light absorber formed on a glass substrate according to Example 3 were produced by the same method and under the same conditions as in Example 2, except that the raw materials and the amounts of the raw materials added were adjusted as shown in Table 1. The transmission spectrum, reflection spectrum, haze value, and thickness of the light absorber formed on the glass substrate according to Example 3, and the transmission spectrum of the dispersion of the light-absorbing compound according to Example 3 were measured by the same method and under the same conditions as in Example 1.

[0163] 7 shows the transmission spectrum at each incident angle of the light absorber according to Example 3. Table 3 shows the characteristics corresponding to the above conditions (I) to (VII) of the light absorber formed on the glass substrate according to Example 3 at an incident angle of 0° or an incident angle of 5°. Tables 4 and 5 show predetermined characteristics at each incident angle of the light absorber formed on the glass substrate according to Example 3. Table 3 shows the haze value (0.12%) of the light absorber formed on the glass substrate according to Example 3 and the thickness (180 μm) of the light absorber according to Example 3.

[0164] Example 4 A light-absorbing compound, a dispersion of the light-absorbing compound, a light-absorbing composition, and a light absorber formed on a glass substrate according to Example 4 were produced by the same method and under the same conditions as in Example 2, except that the raw materials and the amounts of the raw materials added were adjusted as shown in Table 1. The transmission spectrum, reflection spectrum, haze value, and thickness of the light absorber formed on the glass substrate according to Example 4, and the transmission spectrum of the dispersion of the light-absorbing compound according to Example 4 were measured by the same method and under the same conditions as in Example 1.

[0165] FIG. 8A shows the transmission spectrum of the light absorber formed on the glass substrate according to Example 4 at each incident angle. FIG. 8B shows the transmission spectrum of the dispersion of the light-absorbing compound according to Example 4. Table 3 shows the characteristics of the light absorber formed on the glass substrate according to Example 4 at an incident angle of 0° or an incident angle of 5°, corresponding to the above conditions (I) to (VII). Tables 4 and 5 show predetermined characteristics of the light absorber formed on the glass substrate according to Example 4 at each incident angle. Table 6 shows characteristic values ​​determined from the transmission spectrum of the dispersion of the light-absorbing compound. Table 3 shows the haze value (0.08%) of the light absorber formed on the glass substrate according to Example 4 and the thickness (171 μm) of the light absorber according to Example 4.

[0166] Examples 5 to 12 Light-absorbing compounds, dispersions of light-absorbing compounds, light-absorbing compositions, and light absorbers formed on glass substrates according to Examples 5 to 12 were produced by the same method and under the same conditions as in Example 1, except that the raw materials and the amounts of the raw materials added were adjusted as shown in Table 1. The transmission spectra, reflection spectra, haze values, and thicknesses of the light absorbers formed on glass substrates according to Examples 5 to 12, and the transmission spectra of the dispersions of light-absorbing compounds according to Examples 5, 8, and 10 were measured by the same method and under the same conditions as in Example 1.

[0167] 9A, 9B, and 9C show the transmission spectrum of the light absorber at each incident angle, the reflection spectrum of the light absorber at each incident angle, and the transmission spectrum of a dispersion of a light-absorbing compound, respectively, according to Example 5. FIG. 10 shows the transmission spectrum of the light absorber at each incident angle, according to Example 6. FIG. 11 shows the transmission spectrum of the light absorber at each incident angle, according to Example 7. FIGS. 12A, 12B, and 12C show the transmission spectrum of the light absorber at each incident angle, the reflection spectrum of the light absorber at each incident angle, and the transmission spectrum of a dispersion of a light-absorbing compound, respectively, according to Example 8. FIG. 13 shows the transmission spectrum of the light absorber at a 0° incident angle, according to Example 9. FIGS. 14A and 14B show the transmission spectrum of the light absorber at a 0° incident angle, according to Example 10, and the transmission spectrum of a dispersion of a light-absorbing compound, respectively. FIG. 15 shows the transmission spectrum of the light absorber at a 0° incident angle, according to Example 11. FIG. 16 shows the transmission spectrum of the light absorber according to Example 12 at an incident angle of 0°.

[0168] Table 3 shows the properties of the light absorbers according to Examples 5 to 12 at an incident angle of 0° or an incident angle of 5°, corresponding to the above conditions (I) to (VII). Tables 4 and 5 show predetermined properties of the light absorbers according to Examples 5 to 12 at each incident angle. Table 6 shows characteristic values ​​determined from the transmission spectra of the dispersions of the light-absorbing compounds according to Examples 5, 8, and 10. Table 3 shows the haze values ​​and thicknesses (171 μm) of the light absorbers according to Examples 5 to 12.

[0169] Example 13 A light-absorbing compound, a dispersion of a light-absorbing compound, a light-absorbing composition, and a light absorber according to Example 13 were prepared by the same method and under the same conditions as in Example 1, except that the raw materials and the amounts of the raw materials added were adjusted as shown in Table 1.

[0170] An antireflection film was formed on both main surfaces of the light absorber of Example 13 to obtain an optical filter of Example 13. Appropriate amounts of methyltriethoxysilane (MTES), tetraethoxysilane (TEOS), water for hydrolysis, and ethanol were mixed and stirred to prepare an antireflection film coating agent, which is a precursor to the antireflection film. The antireflection film coating agent was applied to both main surfaces of the light absorber of Example 13. The antireflection film coating agent was applied to one main surface of the light absorber at a time. After application of the antireflection film coating agent to one main surface, the antireflection film coating agent was left to stand for about one minute until the surface coated with the antireflection film coating agent was confirmed to be dry, and then the antireflection film coating agent was applied to the other main surface in the same manner. The light absorber was then placed in a thermostatic chamber and heated for one hour in an 85°C atmosphere to evaporate and remove excess solvent and by-products, resulting in antireflection films being formed on both main surfaces of the light absorber. The antireflection film was porous and had a thickness of about 180 nm on both main surfaces. In this way, an optical filter according to Example 13 having an antireflection film was obtained.

[0171] 17A and 17B show the transmission spectrum at each incident angle of the optical filter according to Example 13 and the reflection spectrum at each incident angle of the optical filter according to Example 13, respectively. These transmission spectra and reflection spectra were obtained using the same method and conditions as in Example 1. Table 3 shows the characteristic values ​​corresponding to the above conditions (I) to (VII) of the optical filter according to Example 13 at an incident angle of 0° or an incident angle of 5°. Tables 4 and 5 show predetermined characteristics of the optical filter according to Example 13 at each incident angle. Table 6 shows characteristic values ​​determined from the transmission spectrum of the dispersion of the light-absorbing compound according to Example 13. The transmission spectrum of the dispersion of the light-absorbing compound according to Example 13 was obtained using the same method and conditions as in Example 1. Table 3 shows the haze value and the thickness of the light absorber of the optical filter according to Example 13.

[0172] <Comparative Examples 1 and 2> A light-absorbing compound, a dispersion of a light-absorbing compound, a light-absorbing composition, and a light absorber according to Comparative Examples 1 and 2 were prepared by the same method and conditions as in Example 1, except that the raw materials and the amounts of the raw materials added were adjusted as shown in Table 1. In Comparative Example 1, the ratio of the arylphosphonic acid content to the alkylphosphonic acid content was 9.414 on a mass basis, and in Comparative Example 2, the ratio of the arylphosphonic acid content to the alkylphosphonic acid content was 12.983 on a mass basis. The transmission spectrum, reflection spectrum, haze value, and thickness of the light absorbers according to Comparative Examples 1 and 2 were measured by the same method and conditions as in Example 1.

[0173] 18 and 19 show the transmission spectra of the light absorbers according to Comparative Examples 1 and 2 at an incident angle of 0°, respectively. Table 3 shows characteristic values ​​corresponding to the above conditions (I) to (VII) of the optical filter according to Example 13 at an incident angle of 0° or an incident angle of 5°. Table 6 shows the haze values ​​and thicknesses of the light absorbers according to Comparative Examples 1 and 2. The haze values ​​of the light absorbers according to Comparative Examples 1 and 2 were 0.38 and 7.75, respectively.

[0174] Reference Examples 1 and 2 A light-absorbing compound, a dispersion of a light-absorbing compound, a light-absorbing composition, and a light absorber according to Reference Examples 1 and 2 were prepared by the same method and conditions as in Example 1, except that the raw materials and the amounts of the raw materials added were adjusted as shown in Table 1. In Reference Examples 1 and 2, the ratio of the arylphosphonic acid content to the alkylphosphonic acid content was 1.620 on a substance amount basis. The transmission spectrum, reflection spectrum, haze value, and thickness of the light absorbers according to Reference Examples 1 and 2 were measured by the same method and conditions as in Example 1.

[0175] 20A and 21A show the transmission spectra at an incident angle of 0° of the light absorbers according to Reference Examples 1 and 2, respectively. 20B and 21B show the transmission spectra in a wavelength range of 400 nm to 500 nm of the transmission spectra at an incident angle of 0° of the light absorbers according to Reference Examples 1 and 2, respectively, and the rate of change of transmittance with respect to wavelength, dT / dλ. In the transmission spectra of the light absorbers according to Reference Examples 1 and 2, a step is observed in a wavelength range of 420 nm to 480 nm, and the rate of change of transmittance with respect to wavelength at a wavelength of 420 nm to 480 nm has a minimum value of 0.1 [% / nm] or less in a wavelength range of 440 nm to 460 nm, and the difference between the maximum and minimum values ​​of the rate of change of transmittance with respect to wavelength in the wavelength range of 420 nm to 480 nm exceeds 0.4 [% / nm].

[0176] Table 3 shows the characteristic values ​​corresponding to the above conditions (I) to (VII) of the optical filters according to Reference Examples 1 and 2 at an incident angle of 0° or an incident angle of 5°. In addition, Table 3 shows the haze values ​​and thicknesses of the light absorbers according to Reference Examples 1 and 2. The haze values ​​of Reference Examples 1 and 2 were 0.14 and 0.16, respectively.

[0177]

[0178]

[0179]

[0180]

[0181]

[0182]

Claims

1. A copper component, It contains phosphonic acid, Having less than 0.20% haze, Light absorber.

2. The phosphonic acid is A monophosphonic acid represented by the following formula (a), The compound comprises a depticon represented by the following formula (b), In the following equation (a), R 1 This is an alkyl group or a halogenated alkyl group in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom. In the following equation (b), R 2 This is an aryl group or a modified aryl group in which at least one hydrogen atom in the aryl group is substituted with a halogen atom, a nitro group, or a hydroxyl group. The light absorber according to claim 1. 【Chemistry 1】

3. The ratio of the content of the secondary phosphonic acid to the content of the primary phosphonic acid is 1.8 to 9 on a molar basis. The light absorber according to claim 2.

4. The ratio of the sum of the content of the first phosphonic acid and the content of the second phosphonic acid to the content of the copper component is 0.3 to 3 on a molar basis. The light absorber according to claim 3.

5. The ratio of the content of the primary phosphonic acid to the content of the copper component is 0.05 to 0.8 on a molar basis. The ratio of the content of the secondary phosphonic acid to the content of the copper component is 0.2 to 1.5 on a molar basis. The light absorber according to claim 4.

6. The light absorber further comprises a metal component other than the copper component, The mass ratio of the copper content to the metal content is 1 × 10² to 7 × 10². The light absorber according to claim 1.

7. The light absorber is capable of transmitting light having a first transmission spectrum for incident light with an incident angle of 0° having a wavelength in the range of 300 nm to 1200 nm, The aforementioned first transmission spectrum satisfies the following conditions (I), (II), (III), (IV), and (V): The light absorber according to claim 1. (I) The average transmittance in the wavelength range of 460 nm to 600 nm is 75% or higher. (II) The short-wavelength cutoff wavelength at which the transmittance is 50% in the wavelength range of 350 nm to 450 nm is 390 nm to 450 nm. (III) The long-wavelength cutoff wavelength at which the transmittance is 50% in the wavelength range of 600 nm to 700 nm is 600 nm to 680 nm. (IV) The average transmittance in the wavelength range of 300 nm to 380 nm is 1.2% or less. (V) The average transmittance in the wavelength range of 750 nm to 1100 nm is 1.2% or less.

8. A light-absorbing compound, A primary light-absorbing compound containing a copper component and a primary phosphonic acid represented by the following formula (a), A deuterated light-absorbing compound comprising a copper component and a deuterated phosphonic acid represented by the following formula (b), In the following equation (a), R 1 This is an alkyl group or a halogenated alkyl group in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom. In the following equation (b), R 2 This is an aryl group or a modified aryl group in which at least one hydrogen atom in the aryl group is substituted with a halogen atom, a nitro group, or a hydroxyl group. The dispersion of the light-absorbing compound is capable of transmitting light having a second transmission spectrum for incident light with an incident angle of 0° having a wavelength in the range of 300 nm to 1600 nm. The second transmission spectrum satisfies the following conditions (i), (ii), (iii), and (iv): Light-absorbing compounds. (i) The average transmittance in the wavelength range of 460 nm to 600 nm is 85% or higher. (ii) The short-wavelength cutoff wavelength at which the transmittance is 50% in the wavelength range of 350 nm to 450 nm is 380 nm to 420 nm. (iii) The long-wavelength cutoff wavelength at which the transmittance is 50% in the wavelength range of 600 nm to 700 nm is 600 nm to 650 nm. (iv) The average transmittance in the wavelength range of 725 nm to 1000 nm is 5% to 20%. 【Chemistry 2】

9. The ratio of the content of the secondary phosphonic acid to the content of the primary phosphonic acid is 1.8 to 9 on a molar basis. The light-absorbing compound according to claim 8.

10. The ratio of the sum of the content of the first phosphonic acid and the content of the second phosphonic acid to the content of the copper component is 0.3 to 3 on a molar basis. The light-absorbing compound according to claim 8.

11. The ratio of the content of the primary phosphonic acid to the content of the copper component is 0.05 to 0.8 on a molar basis. The ratio of the content of the secondary phosphonic acid to the content of the copper component is 0.2 to 1.5 on a molar basis. The light-absorbing compound according to claim 8.

12. A primary light-absorbing compound containing a copper component and a primary phosphonic acid represented by the following formula (a), A deuterated light-absorbing compound comprising a copper component and a deuterated phosphonic acid represented by the following formula (b), Solvent and, A curable resin, In the following equation (a), R 1 This is an alkyl group or a halogenated alkyl group in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom. In the following equation (b), R 2 This is an aryl group or a modified aryl group in which at least one hydrogen atom in the aryl group is substituted with a halogen atom, a nitro group, or a hydroxyl group. The ratio of the content of the secondary phosphonic acid to the content of the primary phosphonic acid is 1.8 to 9 on a molar basis. Light-absorbing composition. 【Transformation 3】

13. The ratio of the sum of the content of the first phosphonic acid and the content of the second phosphonic acid to the content of the copper component is 0.3 to 3 on a molar basis. The light-absorbing composition according to claim 12.

14. The ratio of the content of the primary phosphonic acid to the content of the copper component is 0.05 to 0.8 on a molar basis. The ratio of the content of the secondary phosphonic acid to the content of the copper component is 0.2 to 1.5 on a molar basis. The light-absorbing composition according to claim 12.

15. The light-absorbing composition can be solidified into a light-absorbing material having less than 0.20% haze, The light absorber is capable of transmitting light having a third transmission spectrum for incident light with an incident angle of 0° having a wavelength in the range of 300 nm to 1200 nm. The third transmission spectrum satisfies the following conditions (I), (II), (III), (IV), and (V): The light-absorbing composition according to any one of claims 12 to 14. (I) The average transmittance in the wavelength range of 460 nm to 600 nm is 75% or higher. (II) The short-wavelength cutoff wavelength at which the transmittance is 50% in the wavelength range of 350 nm to 450 nm is 390 nm to 450 nm. (III) The long-wavelength cutoff wavelength at which the transmittance is 50% in the wavelength range of 600 nm to 700 nm is 600 nm to 680 nm. (IV) The average transmittance in the wavelength range of 300 nm to 380 nm is 1.2% or less. (V) The average transmittance in the wavelength range of 750 nm to 1100 nm is 1.2% or less.

16. An optical filter comprising a light absorber according to any one of claims 1 to 7.

17. An object having a light-receiving surface, A light absorber according to any one of claims 1 to 7, comprising: The light absorber is provided such that light transmitted through the light absorber is incident on the light receiving surface. Photoelectric conversion element.

18. An ambient light sensor comprising the optical filter described in claim 16.

19. An imaging device comprising a light absorber according to any one of claims 1 to 7.

20. Multiple lenses, The light absorber is provided on the surface of at least one lens of the plurality of lenses, Equipped with an image sensor and, in order, The imaging device according to claim 19.

Images