Optical filter, solid-state imaging device, and camera module

Abstract

To provide an optical filter which improves defects of a conventional optical filter, suppresses the occurrence of flare, particularly the occurrence of fluorescence in a near-infrared region, is excellent in visible light transmittance and has little haze.SOLUTION: A layer 1, a layer 2, and a layer 3, in which the layer 2 is located between the layer 1 and the layer 3, the layer 1 contains a near infrared absorber 11 having a maximum absorption at 650 to 800nm, the layer 2 contains a near infrared absorber 22 having a maximum absorption at 670 to 1000nm, the layer 3 contains a near infrared absorber 33 having a maximum absorption at 720 to 1700nm, and when the maximum absorption of the near infrared absorber 11 is denoted by λ 1 (nm), when an absorption maximum wavelength of the near-infrared absorber 22 is λ 2 (nm) and an absorption maximum wavelength of the near-infrared absorber 33 is λ 3 (nm), λ 1 <λ 2 <λ 3 is satisfied.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an optical filter, and a solid-state imaging device and a camera module that use the optical filter. [Background technology]

[0002] Solid-state imaging devices such as video cameras, digital still cameras, and mobile phones with camera functions use CCD and CMOS image sensors, which are solid-state imaging elements for color images. These solid-state imaging elements use silicon photodiodes in their light-receiving sections that are sensitive to near-infrared light, which the human eye cannot perceive. These solid-state imaging elements require luminosity correction to ensure that the images they produce have natural colors as seen by the human eye, and often use optical filters (e.g., near-infrared cut filters) that selectively transmit or block light in specific wavelength ranges.

[0003] As such near-infrared cut filters, filters manufactured by various methods have been used. For example, Patent Document 1 proposes a near-infrared cut filter that uses a transparent resin as a substrate and blends a squarylium dye as a near-infrared absorbing dye into the transparent resin, has a sufficient viewing angle, and can be suitably used particularly as a visibility correction filter for solid-state imaging devices such as CCD and CMOS.

[0004] In addition, squarylium dyes generally have a tendency to fluoresce due to their molecular structure, and may emit fluorescence when absorbing light, which can degrade the image quality of the camera. For this reason, Patent Document 2 proposes an optical filter that has low fluorescence transmission and excellent transmittance characteristics by using, as a near-infrared absorbing dye, a squarylium compound in combination with a specific compound that absorbs or quenches fluorescence that can be generated from the squarylium compound.

[0005] In recent years, with improvements in the performance and quantum yield of solid-state imaging devices, when optical filters of conventional configurations are used, the fluorescence that can be generated from the optical filters is insufficient, and when an image is captured around a light source of a specific wavelength, an image defect called flare occurs, in which a color different from the actual color is produced.

[0006] Regarding suppressing this flare, Patent Document 3 reports an optical filter having a laminate including a near-infrared absorbing glass substrate and a light absorbing layer, and having an average transmittance of 1% or less for light in a wavelength region of 720 to 780 nm. Patent Document 3 also reports an optical filter including three or more agents selected from the group consisting of a first near-infrared absorbent having an absorption maximum wavelength in the range of 700 nm to 720 nm, a second near-infrared absorbent having an absorption maximum wavelength in the range of more than 720 nm to 740 nm, a third near-infrared absorbent having an absorption maximum wavelength in the range of more than 740 nm to 760 nm, and a fourth near-infrared absorbent having an absorption maximum wavelength in the range of more than 760 nm to 800 nm. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-8532 [Patent Document 2] International Publication No. 2013 / 054864 [Patent Document 3] Japanese Patent Application Laid-Open No. 2024-4467 Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, optical filters capable of suppressing flare are known. However, in recent years, the sensitivity of solid-state imaging devices has improved, and when the above-described conventional optical filters are used as optical filters for such solid-state imaging devices with improved sensitivity, flare may not be sufficiently suppressed.

[0009] An object of the present invention is to provide an optical filter which overcomes the drawbacks of conventional optical filters, suppresses the generation of flare, particularly the generation of fluorescence in the near-infrared region, has excellent visible light transmittance, and has little haze. [Means for solving the problem]

[0010] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by the following configuration examples, and have thus completed the present invention. An example of the configuration of the present invention is as follows.

[0011] [1] Having Layer 1, Layer 2, and Layer 3, the layer 2 is located between the layer 1 and the layer 3; The layer 1 contains a near-infrared absorber 11 having an absorption maximum wavelength of 650 to 800 nm, The layer 2 contains a near-infrared absorber 22 having an absorption maximum wavelength of 670 to 1000 nm, The layer 3 contains a near-infrared absorber 33 having an absorption maximum wavelength of 720 to 1700 nm, The absorption maximum wavelength of the near-infrared absorbent 11 is λ1 (nm), The absorption maximum wavelength of the near-infrared absorber 22 is λ2 (nm), When the absorption maximum wavelength of the near-infrared absorber 33 is λ3 (nm), λ1<λ2<λ3 is satisfied. Optical filter.

[0012] [2] The optical filter according to [1], wherein at least one of the layers 1 to 3 is an absorptive resin layer containing a resin, and the content of the near-infrared absorbent having an absorption maximum wavelength of 650 to 1700 nm in the absorptive resin layer is 0.01 parts by mass or more per 100 parts by mass of the resin.

[0013] [3] The optical filter according to [2], wherein at least two of the layers 1 to 3 are absorptive resin layers containing a resin, and the content of the near-infrared absorbent having an absorption maximum wavelength of 650 to 1700 nm in the absorptive resin layer is 0.01 parts by mass or more per 100 parts by mass of the resin.

[0014] [4] The optical filter according to any one of [1] to [3], wherein the side of the layer 2 on which the layer 1 is located is used as the light incident side.

[0015] [5] The optical filter according to any one of [1] to [4], which has an average transmittance of 70% or more for light with wavelengths of 450 to 600 nm.

[0016] [6] The optical filter according to any one of [1] to [5], which has a dielectric multilayer film.

[0017] [7] A solid-state imaging device comprising the optical filter according to any one of [1] to [6]. [8] A camera module including the optical filter according to any one of [1] to [6]. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide an optical filter that overcomes the drawbacks of conventional optical filters, suppresses the generation of flare, particularly the generation of fluorescence in the near-infrared region, has excellent visible light transmittance, and has little haze (low scattered light intensity). In particular, according to the present invention, it is possible to suppress flare (pink flare) on the long wavelength side. Furthermore, according to one embodiment of the present invention, by using the optical filter, it is possible to provide a solid-state imaging element or a solid-state imaging device that can obtain a desired image in which the occurrence of flare and the like is suppressed. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional schematic explanatory diagram of light absorption and fluorescence generation in the optical filters described in Patent Documents 2 and 3. In FIG. [Figure 2] FIG. 2 is an example of a cross-sectional schematic explanatory diagram relating to light absorption and fluorescence generation in an optical filter according to one embodiment of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view of an optical filter according to one embodiment of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view of an example in which an optical filter according to an embodiment of the present invention is used in an imaging device or the like. [Figure 5] FIG. 5 is an example of a cross-sectional schematic explanatory diagram relating to light absorption and fluorescence generation in an optical filter having a dielectric multilayer film according to one embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram illustrating the measurement of transmittance in the following examples. [Figure 7] FIG. 7 is a schematic diagram illustrating the measurement of reflectance in the following examples. [Figure 8] FIG. 8 is a schematic diagram showing the haze measurement in the following examples. [Figure 9] FIG. 9 shows the spectral transmittance curve and the spectral reflectance curve of the absorbent laminate 1 obtained in Example 1 below. [Figure 10] FIG. 10 is a spectral haze curve of the absorber laminate 1 obtained in Example 1 below. [Figure 11] FIG. 11 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the dielectric multilayer film-attached optical filter 1 obtained in Example 1 below. [Figure 12] FIG. 12 shows the spectral transmittance curve and the spectral reflectance curve of the absorbent laminate 2 obtained in Example 2 below. [Figure 13] FIG. 13 is a spectral haze curve of the absorber laminate 2 obtained in Example 2 below. [Figure 14] FIG. 14 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the optical filter 2 with a dielectric multilayer film obtained in Example 2 below. [Figure 15] FIG. 15 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate 3 obtained in Example 3 below. [Figure 16] FIG. 16 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the optical filter 3 with a dielectric multilayer film obtained in Example 3 below. [Figure 17]FIG. 17 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate 4 obtained in Example 4 below. [Figure 18] FIG. 18 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the dielectric multilayer film-attached optical filter 4 obtained in Example 4 below. [Figure 19] FIG. 19 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate 5 obtained in Example 5 below. [Figure 20] FIG. 20 is a spectral haze curve of the absorber laminate 5 obtained in Example 5 below. [Figure 21] FIG. 21 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the dielectric multilayer film-attached optical filter 5 obtained in Example 5 below. [Figure 22] FIG. 22 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate 6 obtained in Example 6 below. [Figure 23] FIG. 23 is a spectral haze curve of the absorber laminate 6 obtained in Example 6 below. [Figure 24] FIG. 24 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the optical filter 6 with a dielectric multilayer film obtained in Example 6 below. [Figure 25] FIG. 25 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate 7 obtained in Example 7 below. [Figure 26] FIG. 26 is a spectral haze curve of the absorber laminate 7 obtained in Example 7 below. [Figure 27] FIG. 27 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the dielectric multilayer film-attached optical filter 7 obtained in Example 7 below. [Figure 28] FIG. 28 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate 8 obtained in Example 8 below. [Figure 29] FIG. 29 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the dielectric multilayer film-attached optical filter 8 obtained in Example 8 below. [Figure 30]FIG. 30 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate 9 obtained in Example 9 below. [Figure 31] FIG. 31 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the dielectric multilayer film-attached optical filter 9 obtained in Example 9 below. [Figure 32] FIG. 32 shows the spectral transmittance curve and the spectral reflectance curve of the absorbent laminate 10 obtained in Example 10 below. [Figure 33] FIG. 33 is a spectral haze curve of the absorber laminate 10 obtained in Example 10 below. [Figure 34] FIG. 34 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the optical filter 10 with a dielectric multilayer film obtained in Example 10 below. [Figure 35] FIG. 35 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate 11 obtained in Example 11 below. [Figure 36] FIG. 36 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the optical filter 11 with a dielectric multilayer film obtained in Example 11 below. [Figure 37] FIG. 37 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate C1 obtained in Comparative Example 1 below. [Figure 38] FIG. 38 is a spectral haze curve of the absorber laminate C1 obtained in Comparative Example 1 below. [Figure 39] FIG. 39 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the dielectric multilayer film-attached optical filter C1 obtained in Comparative Example 1 below. [Figure 40] FIG. 40 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate C2 obtained in Comparative Example 2 below. [Figure 41] FIG. 41 is a spectral haze curve of the absorber laminate C2 obtained in Comparative Example 2 below. [Figure 42] FIG. 42 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the dielectric multilayer film-attached optical filter C2 obtained in Comparative Example 2 below. [Figure 43] FIG. 43 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate C3 obtained in Comparative Example 3 below. [Figure 44] FIG. 44 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the dielectric multilayer film-attached optical filter C3 obtained in Comparative Example 3 below. [Figure 45] FIG. 45 shows the spectral transmittance curve and the spectral reflectance curve of the absorber laminate C4 obtained in Comparative Example 4 below. [Figure 46] FIG. 46 is a spectral haze curve of the absorber laminate C4 obtained in Comparative Example 4 below. [Figure 47] FIG. 47 shows the spectral transmittance curve and the spectral reflectance curve (single-surface reflectance and two-surface reflectance) of the dielectric multilayer film-coated optical filter C4 obtained in Comparative Example 4 below. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be specifically described below. In the present invention, the expression "A to B" or the like that expresses a numerical range is synonymous with "A or more, B or less," and A and B are included in the numerical range. In the present invention, optical characteristics (for example, transmittance, reflectance) at wavelengths A to B nm refer to optical characteristics at a wavelength resolution of 1 nm in a wavelength range of wavelengths equal to or greater than wavelength Am and equal to or less than wavelength B nm.

[0021] In the present invention, near-infrared light refers to light with a wavelength of 650 to 1700 nm, which is a wavelength at which human visibility is low among the detection wavelengths of silicon photodiodes, indium gallium arsenide photodiodes, and the like.

[0022] Optical Filter The optical filter according to the present invention (hereinafter also referred to as "the filter") has a layer 1, a layer 2, and a layer 3, and the layer 2 is located between the layer 1 and the layer 3, The layer 1 contains a near-infrared absorber 11 having an absorption maximum wavelength of 650 to 800 nm, The layer 2 contains a near-infrared absorber 22 having an absorption maximum wavelength of 670 to 1000 nm, The layer 3 contains a near-infrared absorber 33 having an absorption maximum wavelength of 720 to 1700 nm, The absorption maximum wavelength of the near-infrared absorbent 11 is λ1 (nm), The absorption maximum wavelength of the near-infrared absorber 22 is λ2 (nm), When the absorption maximum wavelength of the near-infrared absorber 33 is λ3 (nm), λ1<λ2<λ3 is satisfied.

[0023] The reason why this filter exhibits the above-mentioned effects is not entirely clear, but is thought to be as follows. First, Fig. 1 shows a cross-sectional schematic explanatory diagram relating to light absorption and fluorescence generation in the optical filters described in Patent Documents 2 and 3. In Fig. 1, "200" indicates a (conventional) optical filter, "210" indicates a near-infrared absorber, "220" indicates a near-infrared absorber different from the near-infrared absorber 210 (e.g., a compound that absorbs or quenches the fluorescence of the near-infrared absorber 210), and λA, λB, and λC indicate light of certain wavelengths.

[0024] Of the light incident on the optical filter 200, the wavelength of near-infrared light to be blocked is denoted by λA, and the near-infrared absorber 210 absorbs the light of wavelength λA, thereby generating light of wavelength λB (e.g., fluorescence) from the near-infrared absorber 210, and the near-infrared absorber 220 absorbs the light of wavelength λB, thereby generating light of wavelength λC (e.g., fluorescence) from the near-infrared absorber 220. When the light of wavelength λB and the light of wavelength λC are fluorescence, generally, λA<λB<λC due to the Stokes shift. In this case, it has been found that after the near-infrared absorber 210 absorbs the light of wavelength λA near the incident surface of the optical filter 200 (upper part of FIG. 1), the light of wavelength λB generated from the near-infrared absorber 210 can be absorbed by the near-infrared absorber 220, but the light of wavelength λB generated near the exit surface of the optical filter 200 (lower part of FIG. 1) is not absorbed and reaches a sensor, etc. It has also been found that after the near-infrared absorber 220 absorbs the light of wavelength λB, the generated light of wavelength λC is not absorbed by the optical filter 200 and may reach a sensor, etc. It is believed that image defects occur when light of wavelength λB or light of wavelength λC reaches a sensor or the like.

[0025] Figure 2 shows an example of a cross-sectional schematic diagram illustrating the light absorption and fluorescence generation in the present filter. In Figure 2, "10" indicates the present filter, "1" indicates the near-infrared absorber 11 contained in layer 1, "2" indicates the near-infrared absorber 22 contained in layer 2, "3" indicates the near-infrared absorber 33 contained in layer 3, and λA, λB, and λC indicate light of certain wavelengths. When light of wavelength λB and light of wavelength λC are fluorescent, generally, λA<λB<λC due to the Stokes shift. In this case, in the present filter 10, after the near-infrared absorber 11 absorbs the near-infrared light (light of wavelength λA) to be blocked, light of wavelength λB (e.g., fluorescence) may be generated. When light of wavelength λB is generated, the near-infrared absorber 22 absorbs the light of wavelength λB. Furthermore, even if light of wavelength λC (e.g., fluorescence) is generated after the near-infrared absorber 22 absorbs the light of wavelength λB, the light of wavelength λC is absorbed by the near-infrared absorber 33. In this way, the present filter 10 can efficiently block light of wavelength λA, light of wavelength λB, and light of wavelength λC, thereby making it possible to obtain an image with fewer image defects. It should be noted that, although there is a possibility that light of wavelength λD (e.g., fluorescence) longer than wavelength λC may be generated from the near-infrared absorber 33 that has absorbed light of wavelength λC, normally, this light of wavelength λD tends not to have a significant effect on image defects. If light of wavelength λD does have an effect on image defects, it is possible to obtain images with fewer image defects by providing a layer 4 or the like that absorbs light of wavelength λD, by providing a layer (light absorbing layer) until the light that may be generated from the layer closest to the sensor, etc. becomes light of a wavelength that does not affect image defects, by providing a dielectric multilayer film, or the like.

[0026] In view of the above, one embodiment of the present filter is preferably an optical filter having a layer 1 containing a near-infrared absorbent, a layer 2 that absorbs light (e.g., fluorescence) emitted after light is absorbed in layer 1, and a layer 3 that absorbs light (e.g., fluorescence) emitted after light is absorbed in layer 2.

[0027] As described above, since λA<λB<λC is satisfied due to the Stokes shift, the present filter has, in this order, a layer 1 containing a near-infrared absorber 11 having a maximum absorption wavelength of 650 to 800 nm, a layer 2 containing a near-infrared absorber 22 having a maximum absorption wavelength of 670 to 1000 nm, and a layer 3 containing a near-infrared absorber 33 having a maximum absorption wavelength of 720 to 1700 nm (wherein, when the absorption maximum wavelength of the near-infrared absorber 11 is λ1 (nm), the absorption maximum wavelength of the near-infrared absorber 22 is λ2 (nm), and the absorption maximum wavelength of the near-infrared absorber 33 is λ3 (nm), λ1<λ2<λ3 is satisfied).

[0028] The layer 1 may contain one near-infrared absorbent 11, or may contain two or more near-infrared absorbents 11. When the layer 1 contains one near-infrared absorbent 11, the absorption maximum wavelength of the one near-infrared absorbent 11 is the above-mentioned λ1 (nm), and when the layer 1 contains two or more near-infrared absorbents 11, the arithmetic mean value of the absorption maximum wavelengths of the two or more near-infrared absorbents 11 is the above-mentioned λ1 (nm). Similarly, the layer 2 may contain one near-infrared absorbent 22, or may contain two or more types of near-infrared absorbents 22. When the layer 2 contains one near-infrared absorbent 22, the absorption maximum wavelength of the one near-infrared absorbent 22 is the above-mentioned λ2 (nm), and when the layer 2 contains two or more types of near-infrared absorbents 22, the arithmetic mean value of the absorption maximum wavelengths of the two or more types of near-infrared absorbents 22 is the above-mentioned λ2 (nm). Furthermore, the layer 3 may contain one near-infrared absorbent 33, or may contain two or more types of near-infrared absorbents 33. When the layer 3 contains one near-infrared absorbent 33, the absorption maximum wavelength of the one near-infrared absorbent 33 is the above-mentioned λ3 (nm), and when the layer 3 contains two or more types of near-infrared absorbents 33, the arithmetic mean value of the absorption maximum wavelengths of the two or more types of near-infrared absorbents 33 is the above-mentioned λ3 (nm).

[0029] λ1, λ2 and λ3 are not particularly limited as long as they satisfy the relationship λ1<λ2<λ3. By using a near-infrared absorbent having such λ1, λ2, and λ3, even if light (e.g., fluorescence) is generated from the near-infrared absorbent 11, the light can be absorbed by the layer 2 or the layer 3, and even if light (e.g., fluorescence) is generated from the near-infrared absorbent 22, the light can be absorbed by the layer 3, thereby making it possible to easily obtain an optical filter in which the occurrence of flare, particularly the occurrence of fluorescence in the near-infrared region, is suppressed.

[0030] The quantum yield of sensors such as silicon photodiodes tends to decrease with increasing wavelength. Therefore, in order to prevent image defects, it is important to prevent shorter wavelength light (e.g., near-infrared light) from reaching the sensor. In order to prevent short wavelength light from reaching the sensor, the difference between λ1 and λ2 is preferably 300 nm or less, more preferably 200 nm or less, even more preferably 100 nm or less, and particularly preferably 60 nm or less. Furthermore, in order to efficiently absorb fluorescence that has undergone a Stokes shift from λ1, the difference between λ1 and λ2 is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more.

[0031] Furthermore, since the human visual sensitivity decreases with increasing wavelength, long wavelength emissions cause color defects that are invisible to the human eye. In order to suppress these color defects and to efficiently suppress the emission from λ2, the difference between λ2 and λ3 is preferably 400 nm or less, more preferably 320 nm or less, even more preferably 250 nm or less, and particularly preferably 200 nm or less. Furthermore, in order to efficiently absorb fluorescence that has undergone a Stokes shift from λ2, the difference between λ2 and λ3 is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more.

[0032] Note that Layer 1 may contain a near-infrared absorbent other than near-infrared absorbent 11, Layer 2 may contain a near-infrared absorbent other than near-infrared absorbent 22, and Layer 3 may contain a near-infrared absorbent other than near-infrared absorbent 33. In a suitable example of the present filter, Layer 2 preferably contains a near-infrared absorbent having an absorption maximum wavelength that is equal to or longer than the longest absorption maximum wavelength of the near-infrared absorbents contained in Layer 1, and Layer 3 preferably contains a near-infrared absorbent having an absorption maximum wavelength that is equal to or longer than the longest absorption maximum wavelength of the near-infrared absorbents contained in Layer 2.

[0033] The quantum yield of sensors such as silicon photodiodes tends to decrease with increasing wavelength. Therefore, in order to prevent image defects, it is important to prevent shorter wavelength light (e.g., near-infrared light) from reaching sensors. Therefore, in order to further prevent short wavelength light from reaching sensors, it is preferable that the near-infrared absorbent 11 is a near-infrared absorbent having an absorption maximum wavelength in the range of 650 to 800 nm, and that at least one of the near-infrared absorbents 22 and 33 is a near-infrared absorbent having an absorption maximum wavelength of 800 nm or less (hereinafter, a near-infrared absorbent having an absorption maximum wavelength of 800 nm or less, including the near-infrared absorbent 11, is also referred to as "near-infrared absorbent (s)"). For the same reason, when one of the near-infrared absorbents 22 and 33 is the near-infrared absorbent (s), it is preferable that the near-infrared absorbent 22 is the near-infrared absorbent (s).

[0034] The absorption maximum wavelength of the near-infrared absorbent 11 is in the range of 650 to 800 nm, preferably in the range of 660 to 780 nm, and more preferably in the range of 670 to 760 nm. The wavelength range of the maximum absorption wavelength λ1 is preferably 650 to 800 nm, more preferably 660 to 780 nm, and even more preferably 670 to 760 nm.

[0035] The maximum absorption wavelength of the near-infrared absorbent 22 is in the range of 670 to 1000 nm, preferably 680 to 900 nm, and more preferably 690 to 880 nm. The wavelength range of the maximum absorption wavelength λ2 is preferably 670 to 1000 nm, more preferably 680 to 900 nm, and even more preferably 690 to 880 nm.

[0036] The absorption maximum wavelength of the near-infrared absorbent 33 is in the range of 720 to 1700 nm, preferably 755 to 1400 nm, and more preferably 760 to 1200 nm. The wavelength range of the maximum absorption wavelength λ3 is preferably 720 to 1700 nm, more preferably 755 to 1400 nm, and even more preferably 760 to 1200 nm.

[0037] At least one of the layers 1 to 3 is preferably an absorbing resin layer containing a resin, and the content of the near-infrared absorbent having an absorption maximum wavelength of 650 to 1700 nm in the absorbing resin layer is preferably 0.01 part by mass or more, more preferably 0.01 to 40 parts by mass, even more preferably 0.02 to 30 parts by mass, and particularly preferably 0.04 to 20 parts by mass, relative to 100 parts by mass of the resin. When the content of the near-infrared absorber is within the above range, the occurrence of flare, particularly the occurrence of fluorescence in the near-infrared region, is suppressed, and an optical filter having excellent visible light transmittance and little haze can be easily obtained. For the same reason, at least two of the layers 1 to 3 are preferably absorbing resin layers containing a resin, and the content of the near-infrared absorbent having an absorption maximum wavelength of 650 to 1700 nm in the absorbing resin layer is preferably 0.01 part by mass or more, more preferably 0.01 to 40 parts by mass, even more preferably 0.02 to 30 parts by mass, and particularly preferably 0.04 to 20 parts by mass, relative to 100 parts by mass of the resin.

[0038] When the layer 1 is the absorbing resin layer, the content of the near-infrared absorber 11 in the layer 1 is preferably 0.01 part by mass or more, more preferably 0.01 to 40 parts by mass, even more preferably 0.02 to 30 parts by mass, and particularly preferably 0.04 to 20 parts by mass, relative to 100 parts by mass of the resin. When the layer 2 is the absorbing resin layer, the content of the near-infrared absorber 22 in the layer 2 is preferably 0.01 part by mass or more, more preferably 0.01 to 40 parts by mass, even more preferably 0.02 to 30 parts by mass, and particularly preferably 0.04 to 20 parts by mass, relative to 100 parts by mass of the resin. When the layer 3 is the absorbing resin layer, the content of the near-infrared absorber 33 in the layer 3 is preferably 0.01 part by mass or more, more preferably 0.01 to 40 parts by mass, even more preferably 0.02 to 30 parts by mass, and particularly preferably 0.04 to 20 parts by mass, relative to 100 parts by mass of the resin. When the contents of the near-infrared absorbers 11 to 33 in the layers 1 to 3 are within the above ranges, the occurrence of flare, particularly the occurrence of fluorescence in the near-infrared region, is suppressed, and an optical filter with excellent visible light transmittance and low haze can be easily obtained.

[0039] The quantum yield of sensors such as silicon photodiodes tends to decrease as the wavelength increases. Therefore, the concentration of the near-infrared absorbent in a layer containing the near-infrared absorbent having a short absorption maximum wavelength (e.g., 800 nm or shorter) is preferably high from the viewpoint of further suppressing light of the short wavelength from reaching the sensor or the like. For this reason, the concentration (content) of the near-infrared absorbent (s) in an absorbing resin layer (hereinafter also referred to as "layer S") containing a resin and the near-infrared absorbent (s) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the resin, and from the viewpoint of visible light transmittance, etc., the upper limit is preferably 40 parts by mass or less. A layer S having a concentration (content) of the near-infrared absorbent (s) within the above range can be said to have a high concentration of the near-infrared absorbent (s) in the layer S, and exhibits desired optical properties even when the thickness of the layer S is reduced. For this reason, it is preferable to reduce the thickness of the layer S having a concentration (content) of the near-infrared absorbent (s) within the above range (e.g., 40 μm or less), in which case the average distance between the near-infrared absorbents in the layer S can be reduced, and a layer S having such a short average distance between the near-infrared absorbents can easily suppress fluorescence that may be generated from the layer S.

[0040] Furthermore, in order to ensure that the near-infrared absorbent 22 and the near-infrared absorbent 33 sufficiently absorb the fluorescence emitted by the near-infrared absorbent 11, and in order to ensure that the near-infrared absorbent 33 sufficiently absorbs the fluorescence emitted by the near-infrared absorbent 22, it is preferable that the sum of the content of the near-infrared absorbent 11 relative to the resin and the content of the near-infrared absorbent 22 relative to the resin be equal to or greater than the content of the near-infrared absorbent 33 relative to the resin. When Layer 1 contains two or more types of near-infrared absorbents 11, the "content of near-infrared absorbents 11 relative to the resin" refers to the sum of the contents of the two or more types of near-infrared absorbents 11 relative to the resin; when Layer 2 contains two or more types of near-infrared absorbents 22, the "content of near-infrared absorbents 22 relative to the resin" refers to the sum of the contents of the two or more types of near-infrared absorbents 22 relative to the resin; and when Layer 3 contains two or more types of near-infrared absorbents 33, the "content of near-infrared absorbents 33 relative to the resin" refers to the sum of the contents of the two or more types of near-infrared absorbents 33 relative to the resin.

[0041] In order for a near-infrared absorber that has absorbed near-infrared radiation to return to its ground state via a process other than emitting fluorescence, it is effective to place a substance in the ground state that receives the excitation energy in the vicinity of the excited-state near-infrared absorber. It is known that when the concentration of near-infrared absorber in a layer is high, the near-infrared absorber that has absorbed near-infrared radiation returns to its ground state without emitting fluorescence, a phenomenon known as concentration quenching, in which the near-infrared absorber that has absorbed near-infrared radiation returns to its ground state without emitting fluorescence, is caused by the proximity of the near-infrared absorber that has absorbed near-infrared radiation to a near-infrared absorber of the same type in the ground state. As a result of extensive research by the present inventors, it has been found that, among the concentration quenching methods, Förster energy transfer, which depends on the intermolecular distance, is effective in the present invention. It is known that the energy transfer efficiency of Förster energy transfer is inversely proportional to the intermolecular distance, and therefore, in order to suppress fluorescence, it is preferable that the average distance between near-infrared absorbers is short.

[0042] The thickness of each of the layers 1 to 3 is not particularly limited and may be appropriately selected depending on the performance required for each layer (e.g., light absorbency, transparency, light reflectivity), the components used in each layer (e.g., near-infrared absorber), the total thickness of the resulting optical filter, etc., but is usually preferably 1 to 200 μm, and more preferably 1.5 to 200 μm. When the thickness of each of Layers 1 to 3 is equal to or greater than the lower limit, the near-infrared absorbent in each layer can be prevented from becoming excessively concentrated, and poor appearance due to aggregation of the near-infrared absorbent and the generation of fluorescence in the near-infrared region can be suppressed. When the thickness of each of Layers 1 to 3 is equal to or less than the upper limit, the total thickness of the obtained optical filter can be made thin.

[0043] When forming each layer, even if the same mass (g) of near-infrared absorbent is used, a layer with a high concentration of near-infrared absorbent can be easily formed, and a layer with a short average distance between the near-infrared absorbents can be easily formed. From these points of view, the thickness of each of Layers 1 to 3 is preferably 40 μm or less, more preferably 20 μm or less, even more preferably 15 μm or less, and particularly preferably 5 μm or less.

[0044] The present filter is not particularly limited as long as it has the layers 1 to 3 in this order, and may have other layers (membranes) in addition to the layers 1 to 3. The present filter may also have two or more of the layer 1, two or more of the layer 2, two or more of the layer 3, or two or more of the other layers (membranes). For example, when the present filter has two or more layers of the layer 1, these layers may be layers having the same composition, thickness, etc., or may be layers having different compositions, thicknesses, etc., as long as they contain the near-infrared absorbent 11 having an absorption maximum wavelength of λ1 (nm). This also applies to the case where the filter has two or more layers of the layers 2 and 3 or the other layers (films).

[0045] Examples of the other layer (film) include a layer (near-infrared absorbing layer) n containing a near-infrared absorber n n , a layer that absorbs light rays other than near-infrared rays, such as infrared rays and ultraviolet rays, and a conventionally known layer that has been used in an optical filter (e.g., a resin or glass layer (substrate) that does not contain a light absorbent, an adhesive layer, a dielectric multilayer film, and other functional films [e.g., an anti-reflection film, a hard coat film, an anti-static film]).

[0046] For example, the present filter may have, as the layer n, a layer 4 containing a near-infrared absorbent 44 having a maximum absorption wavelength of λ4 (nm) for the purpose of improving near-infrared absorption characteristics and the like. The content of the near-infrared absorbing agent in the layer n (eg, layer 4) and the preferred range of the thickness of the layer n (eg, layer 4) are the same as those of the layers 1 to 3 described above.

[0047] The relationship between λ4 and λ1 to λ3 is not particularly limited, and examples of such relationships include λ1<λ2<λ3<λ4, λ1<λ2<λ4<λ3, λ1<λ4<λ2<λ3, λ4<λ1<λ2<λ3, etc. When fluorescence is generated from λ3, it is possible to absorb the fluorescence, and so on. From this viewpoint, λ1<λ2<λ3<λ4 is most preferred. The relationship (stacking order) between Layer 4 and Layers 1 to 3 is not particularly limited, and examples of such stacking orders include Layer 1 / Layer 2 / Layer 3 / Layer 4, Layer 1 / Layer 2 / Layer 4 / Layer 3, Layer 1 / Layer 4 / Layer 2 / Layer 3, and Layer 4 / Layer 1 / Layer 2 / Layer 3. Here, "Layer 1 / Layer 2 / Layer 3 / Layer 4" means that Layer 1, Layer 2, Layer 3, and Layer 4 are stacked in this order. A schematic cross-sectional view of the present filter in the case of Layer 1 / Layer 2 / Layer 4 / Layer 3 is shown in Figure 3. In FIG. 3 , “10” indicates the present filter, “1” indicates the near-infrared absorbent 11 contained in layer 1, “2” indicates the near-infrared absorbent 22 contained in layer 2, “3” indicates the near-infrared absorbent 33 contained in layer 3, and “4” indicates the near-infrared absorbent 44 contained in layer 4.

[0048] The relationship between λ1 to λ4 and the stacking order of Layers 1 to 4 is not particularly limited, but when λ1<λ2<λ3<λ4, Layer 1 / Layer 2 / Layer 3 / Layer 4 is preferred; when λ1<λ2<λ4<λ3, Layer 1 / Layer 2 / Layer 4 / Layer 3 is preferred; when λ1<λ4<λ2<λ3, Layer 1 / Layer 4 / Layer 2 / Layer 3 is preferred; and when λ4<λ1<λ2<λ3, Layer 4 / Layer 1 / Layer 2 / Layer 3 is preferred. From the viewpoint of easily obtaining an optical filter in which the occurrence of flare, particularly the occurrence of fluorescence in the near-infrared region, is suppressed, it is preferable that λ1<λ2<λ3<λ4 and the layers are layer 1 / layer 2 / layer 3 / layer 4, or that λ4<λ1<λ2<λ3 and the layers are layer 4 / layer 1 / layer 2 / layer 3.

[0049] When the present filter is used in an imaging device or the like, it is preferable to use the present filter so that the absorption maximum wavelength of the near-infrared absorbent in the layer closest to the light emission side is greater than the absorption maximum wavelengths of the near-infrared absorbents contained in the other layers, in order to be able to efficiently shield fluorescence that may be generated from the near-infrared absorbent, etc. In other words, when the present filter has a layer 1 / layer 2 / layer 3 structure, it is preferable to use the layer 3 side as the light emission side and the layer 1 side as the light incidence side (the side on which the layer 1 is located relative to the layer 2 is used as the light incidence side). As an example of use of the present filter, a schematic cross-sectional view of an example of use of the present filter in an imaging device, etc. is shown in Figure 4. In Figure 4, "10" indicates the present filter, "110" indicates a lens, "120" indicates a housing, "130" indicates an image sensor, "140" indicates an image sensor frame, and "150" indicates a substrate. When this filter is used as shown in FIG. 4, the upper side of this filter 10 is the incident side of the light, and the lower side of this filter 10 (the image sensor 130 side) is the exit side of the light.

[0050] <Components of Layers 1 to 3> The layers 1 to 3 are not particularly limited as long as they contain near-infrared absorbents 11, 22, or 33, respectively, but are preferably absorbing resin layers containing a resin and a near-infrared absorbent, or absorbing glass layers (blue glass [BG]) containing glass and a near-infrared absorbent. The layer n (eg, layer 4) is also preferably an absorbing resin layer or an absorbing glass layer. The layers 1 to 3 and n may also contain additives other than the resin, glass, and near-infrared absorbing agent. Each layer may contain one or more types of near-infrared absorbents, each layer may contain one or more types of resins, each layer may contain one or more types of glasses, and each layer may contain one or more types of additives.

[0051] [Near infrared absorber] The near-infrared absorbents 11, 22, and 33 are near-infrared absorbents having the respective maximum absorption wavelengths, and any known near-infrared absorbents can be used. The near-infrared absorber nn (e.g., near-infrared absorber 44) is not particularly limited as long as it is an agent that absorbs near-infrared rays, but it preferably has an absorption maximum wavelength in the range of 650 to 1700 nm. The near-infrared absorber nn preferably has an absorption maximum wavelength in the range of 660 to 1600 nm, more preferably has an absorption maximum wavelength in the range of 670 to 1550 nm, and further preferably has an absorption maximum wavelength in the range of 670 to 1400 nm.

[0052] The absorption maximum wavelength of the near-infrared absorbent is measured from the transmittance of a film obtained by using 0.01 part by mass of the near-infrared absorbent per 100 parts by mass of Resin 1 described in the Examples below, as measured using a spectrophotometer (U-4100 manufactured by Hitachi High-Technologies Corporation). Specifically, it is measured by the method described in the Examples below. The maximum absorption wavelength of the near-infrared absorbent contained in the absorbing glass layer (blue glass [BG]) is measured from the transmittance of the absorbing glass layer using a spectrophotometer (U-4100 manufactured by Hitachi High-Technologies Corporation). Since glass generally does not have a maximum absorption wavelength in the near-infrared region, the maximum absorption wavelength of the absorbing glass layer in the near-infrared region is taken as the maximum absorption wavelength of the near-infrared absorbent contained in the absorbing glass layer.

[0053] The near-infrared absorbing agent is not particularly limited and may be any of inorganic compounds, organic compounds, and organic-inorganic compounds. For example, various known compounds used as dyes or pigments can be used.

[0054] Specific examples of near-infrared absorbers include azo compounds, azomethine compounds, azopyridone compounds, pyrazolone azo compounds, indole compounds, anthraquinone compounds, quinophthalone compounds, coumarin compounds, dipyrromethene compounds, pyrrolopyrrole compounds, diketopyrrolopyrrole compounds, diphenylmethane compounds, diimonium compounds, triarylmethane compounds, xanthene compounds, acridine compounds, polymethine compounds, oxonol compounds, merocyanine compounds, arylidene compounds, benzylidene compounds, cyanine compounds, squarylium compounds, croconium compounds, perylene compounds, dioxazine compounds, phthalocyanine compounds, porphyrin compounds, tetraazaporphyrin compounds, subphthalocyanine compounds, metal chelate compounds thereof, metal dithiolate compounds, copper complex compounds, and iron complex compounds.

[0055] The polymethine compounds are polymethine compounds excluding oxonol compounds, merocyanine compounds, arylidene compounds, benzylidene compounds, cyanine compounds, squarylium compounds, and croconium compounds, and the phthalocyanine compounds are phthalocyanine compounds excluding porphyrin compounds and tetraazaporphyrin compounds.

[0056] Among these, the near-infrared absorbing agent used in the absorbing resin layer may be an azomethine-based compound, an azopyridone-based compound, a pyrazolone azo-based compound, an indole-based compound, an anthraquinone-based compound, a coumarin-based compound, a dipyrromethene-based compound, a diimonium-based compound, a triarylmethane-based compound, a xanthene-based compound, a polymethine-based compound, a merocyanine-based compound, a benzylidene-based compound, a cyanine-based compound, a squarylium-based compound, a croconium-based compound, a perylene-based compound, a dioxazine-based compound, a phthalocyanine-based compound, a porphyrin-based compound, a tetraazaporphyrin-based compound, a subphthalocyanine-based compound, or any of these compounds. At least one selected from metal chelate compounds and copper complex compounds is preferred, and at least one selected from azomethine compounds, azopyridone compounds, pyrazolone azo compounds, indole compounds, coumarin compounds, dipyrromethene compounds, diimonium compounds, triarylmethane compounds, xanthene compounds, polymethine compounds, merocyanine compounds, cyanine compounds, squarylium compounds, croconium compounds, phthalocyanine compounds, porphyrin compounds, tetraazaporphyrin compounds, subphthalocyanine compounds, and metal chelate compounds thereof is more preferred.

[0057] In addition, from the viewpoint of solubility in resins, etc., the near-infrared absorber is preferably a compound having at least two benzene rings or heteroaromatic rings. Furthermore, from the viewpoint of solubility in resins, etc., the above-mentioned benzene rings or heteroaromatic rings are preferably polycyclic aromatic rings in which benzene rings and / or heteroaromatic rings are condensed, and the number of condensed polycyclic aromatic rings in which benzene rings and / or heteroaromatic rings are condensed is preferably 3 or less. As the near-infrared absorber having at least two benzene rings or heteroaromatic rings, polymethine compounds, diimonium compounds, cyanine compounds, squarylium compounds, and phthalocyanine compounds are preferred, and from the viewpoint of achieving low fluorescence quantum yield and low scattering intensity, cyanine compounds, squarylium compounds, and phthalocyanine compounds are particularly preferred.

[0058] Specific structures of near-infrared absorbers are described in, for example, "New Edition Dye Handbook" (edited by the Organic Synthetic Chemistry Association; Maruzen, 1970) and "Dye Handbook" (edited by Okawara et al.; Kodansha, 1986).

[0059] Of the above, copper complex compounds are preferred as the near-infrared absorbing agent used in the absorbing glass layer. Specific examples of the copper complex compound include copper phosphate, copper fluorophosphate, copper phosphonate, and complexes of copper ions with compounds having a phosphate ester group.

[0060] [resin] The absorbing resin layer may be formed using a composition containing a near-infrared absorbing agent and a resin, or may be formed using a composition containing a near-infrared absorbing agent and a curable compound. In the present invention, a compound (for example, a curable compound) that is a component constituting the resin in the formed layer may also be referred to as a "resin" for convenience.

[0061] The resin (including the resin obtained from the curable compound) is not particularly limited as long as it does not impair the effects of the present invention, but examples thereof include resins having a glass transition temperature (Tg) of preferably 110 to 380°C, more preferably 110 to 370°C, and even more preferably 120 to 360°C, from the viewpoint of ensuring thermal stability and formability into a layer and easily obtaining a layer having excellent vapor deposition resistance, particularly a layer on which a dielectric multilayer film can be formed by high-temperature vapor deposition at a vapor deposition temperature of about 100°C or higher. Furthermore, resins having a glass transition temperature of 140°C or higher are particularly preferred, because they can obtain a layer having excellent vapor deposition resistance, particularly a layer on which a dielectric multilayer film can be formed by vapor deposition at higher temperatures. The glass transition temperature (Tg) is specifically measured by the method described in the examples below.

[0062] Furthermore, the resin (including the resin obtained from the curable compound) is preferably a transparent resin, and it is desirable to use a resin or curable compound such that the total light transmittance (JIS K 7375:2008) of a 0.1 mm thick film made of the resin or a film obtained from a composition containing the curable compound (but not containing a light absorber such as a near-infrared absorber) is preferably 75 to 95%, more preferably 78 to 95%, and particularly preferably 80 to 95%. By using a resin or a curable compound having a total light transmittance within the above range, a layer or an optical filter exhibiting good transparency can be easily obtained.

[0063] In one embodiment of the present filter, as described above, it is preferable to use a layer having a high concentration of near-infrared absorber in order to suppress fluorescence, etc. On the other hand, in a layer having such a high concentration of near-infrared absorber, breakage is more likely to occur due to a decrease in entanglement between resins, etc. Therefore, in order to suppress such breakage and easily obtain a layer having flexibility that is easy to process, the weight average molecular weight (Mw) of the resin (including the resin obtained from the curable compound) in terms of standard polystyrene is preferably 40,000 or more, more preferably 50,000 or more, even more preferably 75,000 or more, and particularly preferably 100,000 or more. The upper limit of the Mw is not particularly limited, but is, for example, 350,000. A resin having a weight-average molecular weight (Mw) within this range is particularly preferably used in a layer in which the concentration of the near-infrared absorbing agent is 0.01% by mass or more. Specifically, the weight average molecular weight (Mw) is measured by the method described in the examples below.

[0064] Examples of the resin include cyclic (poly)olefin polymers, polyether polymers, polyimide polymers, polyester polymers, polycarbonate polymers, polyamide (aramid) polymers, polyarylate polymers, polysulfone polymers, polyethersulfone polymers, polyparaphenylene polymers, polyamideimide polymers, polyethylene naphthalate polymers, fluorinated aromatic polymer polymers, (modified) (meth)acrylic polymers, and epoxy polymers. Specific examples of these polymers include resins described in WO 2019 / 168090 and JP 2023-027337 A. When a resin is used in the composition, the resin used may be one type or two or more types.

[0065] When the layers 1 to 3 and n are formed from a composition containing a near-infrared absorber, a resin, and a solvent, the content of the resin relative to 100% by mass of the composition is preferably 5 to 30% by mass, and more preferably 10 to 25% by mass, in terms of the viscosity (coatability) of the composition, etc.

[0066] The curable compound is not particularly limited as long as it is a compound that is cured by light or heat. When a curable compound is used in the composition, the curable compound used may be one type or two or more types.

[0067] Examples of the curable compound include epoxy compounds, aryl ester curable compounds, silsesquioxane photocurable compounds, (meth)acrylic photocurable compounds, (meth)acrylic thermosetting compounds, and vinyl photocurable compounds. Among these, epoxy compounds, silsesquioxane photocurable compounds, (meth)acrylic photocurable compounds, and (meth)acrylic thermosetting compounds are preferred.

[0068] (epoxy compounds) Examples of the epoxy compounds include unsaturated compounds having an oxiranyl group, such as (meth)acrylic acid oxiranyl (cyclo)alkyl esters, α-alkylacrylic acid oxiranyl (cyclo)alkyl esters, and glycidyl ether compounds having an unsaturated bond; and unsaturated compounds having an oxetanyl group, such as (meth)acrylic acid esters having an oxetanyl group.

[0069] Examples of (meth)acrylic acid oxiranyl(cyclo)alkyl esters include glycidyl (meth)acrylate, 2-methylglycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, 3,4-epoxybutyl (meth)acrylate, 6,7-epoxyheptyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate. Examples of the α-alkylacrylic acid oxiranyl(cyclo)alkyl ester include glycidyl α-ethylacrylate, glycidyl α-n-propylacrylate, glycidyl α-n-butylacrylate, 6,7-epoxyheptyl α-ethylacrylate, and 3,4-epoxycyclohexyl α-ethylacrylate. Examples of the glycidyl ether compound having an unsaturated bond include o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, and p-vinylbenzyl glycidyl ether. Examples of (meth)acrylic acid esters having an oxetanyl group include 3-((meth)acryloyloxymethyl)oxetane, 3-((meth)acryloyloxymethyl)-3-ethyloxetane, 3-((meth)acryloyloxymethyl)-2-methyloxetane, 3-((meth)acryloyloxyethyl)-3-ethyloxetane, 2-ethyl-3-((meth)acryloyloxyethyl)oxetane, 3-methyl-3-(meth)acryloyloxymethyloxetane, and 3-ethyl-3-(meth)acryloyloxymethyloxetane.

[0070] Among these, glycidyl methacrylate, 2-methylglycidyl methacrylate, 3,4-epoxycyclohexyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, 3-methacryloyloxymethyl-3-ethyloxetane, 3-methyl-3-methacryloyloxymethyloxetane, and 3-ethyl-3-methacryloyloxymethyloxetane are particularly preferred in terms of polymerizability, etc.

[0071] (Silsesquioxane-based photocurable compound) The silsesquioxane-based photocurable compound is preferably a compound represented by the following formula (1). [RSiO 3 / 2 ] n (1) (In formula (1), R is an organic functional group having one of a (meth)acryloyl group, a glycidyl group, an oxetanyl group, and a vinyl group, and n is 8, 10, 12, or 14.)

[0072] Furthermore, the silsesquioxane-based photocurable compound is also preferably a compound obtained by hydrolyzing a silicon compound represented by the following formula (2) in the presence of an organic polar solvent and a basic catalyst, while simultaneously condensing a portion of the compound, and then re-condensing the resulting hydrolysis product in the presence of a non-polar solvent and a basic catalyst. RSiX3(2) (In formula (2), R is an organic functional group having one of a (meth)acryloyl group, a glycidyl group, an oxetanyl group, and a vinyl group, and X is a hydrolyzable group.)

[0073] Examples of the organic functional group having any one of a (meth)acryloyl group, a glycidyl group, an oxetanyl group, and a vinyl group in formulas (1) and (2) include organic functional groups represented by the following formulas (3), (4), (5), and (6).

[0074] [ka] (In formulas (3) and (4), m is an integer of 1 to 3, and in formula (3), R1 is a hydrogen atom or a methyl group.)

[0075] [ka] (In formula (6), R 5 , R 6 , R 7 , R 8 and R 9 are each independently a hydrogen atom, a fluorine atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a perfluoroalkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 6.

[0076] ((Meth)acrylic photocurable compound) Examples of the (meth)acrylic photocurable compound include trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, phenoxyethyl (meth)acrylate, glycerin tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, ethylene glycol di(meth)acrylate, 1,3- Examples of the hydroxyl group-containing (meth)acrylates include butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and bis(2-hydroxyethyl)isocyanurate di(meth)acrylate; poly(meth)acrylates which are adducts of ethylene oxide or propylene oxide to the hydroxyl groups of these; oligoester (meth)acrylates having two or more (meth)acryloyl groups in the molecule; oligoether (meth)acrylates; oligourethane (meth)acrylates; and oligoepoxy (meth)acrylates.

[0077] Among these, tricyclodecane dimethanol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, pentaerythritol tetra(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate are preferred.

[0078] Commercially available (meth)acrylic photocurable compounds include, for example, Aronix, manufactured by Toagosei Co., Ltd. M-400, M-408, M-450, M-305, M-309, M-310, M-315, M-320, M-350, M-360, M-20 8, M-210, M-215, M-220, M-225, M-233, M-240, M-245, M-260, M-270, M-1100, M- KAYARAD manufactured by Nippon Kayaku Co., Ltd. D-310, D-330, DPHA, DPCA-20, DPCA-30, DPCA-60, DPCA-120, DN-0075, DN-2475, SR-295, SR-355, SR-399E, SR-494, SR-9041, SR-368, SR-41 5, SR-444, SR-454, SR-492, SR-499, SR-502, SR-9020, SR-9035, SR-111, SR-212, SR-213, SR-230, SR-259, SR-268, SR-272, SR-344, SR-349 , SR-601, SR-602, SR-610, SR-9003, PET-30, T-1420, GPO-303, TC-120S, HDDA, NPGDA, TPGDA, PEG400DA, MANDA, HX-220, HX-620, R-551, R-7 12, R-167, R-526, R-551, R-712, R-604, R-684, TMPTA, THE-330, TPA-320, TPA-330, KS-HDDA, KS-TPGDA, KS-TMPTA; Light acrylate manufactured by Kyoeisha Chemical Co., Ltd. PE-4A, DPE-6A, DTMP-4A; FA-511AS, FA-512AS manufactured by Resonac Co., Ltd.; and NK Ester A-TMM-3LM-N, A-DPH manufactured by Shin-Nakamura Chemical Co., Ltd.

[0079] When the (meth)acrylic photocurable compound is used, a photopolymerization initiator is usually used together with the (meth)acrylic photocurable compound. When the (meth)acrylic photocurable compound is used, the composition may be a composition containing the (meth)acrylic photocurable compound and a photopolymerization initiator, or a composition containing a cured product obtained by reacting and curing the (meth)acrylic photocurable compound with the photopolymerization initiator.

[0080] The photopolymerization initiator is preferably a compound that can be decomposed by light irradiation to generate radicals and initiate polymerization of a (meth)acrylic photocurable compound. Specific examples thereof include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethan-1-one, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, benzoin propyl ether, benzoin ethyl ether, benzil dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methyl Examples of suitable thioxanthone include 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone).

[0081] Examples of commercially available photopolymerization initiators include Irgacure 184, 369, 651, 500, 819, 907, 784, 2959, CGI1700, CGI1750, CGI1850, CG24-61, Darocur 1116, 1173, and Lucirin TPO, all manufactured by BASF; Ubecryl P36, all manufactured by UCB; and Ezacure KIP150, KIP65LT, KIP100F, KT37, KT55, KTO46, and KIP75 / B, all manufactured by Fratelli Lamberti.

[0082] The amount of the photopolymerization initiator used is preferably 0.5 to 15% by mass, and more preferably 1 to 8% by mass, relative to 100 parts by mass of the (meth)acrylic photocurable compound, in order to enable the (meth)acrylic photocurable compound to be sufficiently cured.

[0083] ((Meth)acrylic thermosetting compounds) The (meth)acrylic thermosetting compound is not particularly limited, but is preferably a copolymer (a12) obtained by using at least one compound (a1) selected from the group consisting of unsaturated carboxylic acids and unsaturated carboxylic acid anhydrides and at least one compound (a2) selected from the group consisting of oxiranyl-group-containing unsaturated compounds and oxetanyl-group-containing unsaturated compounds. Such a copolymer (a12) can be produced by radical copolymerization of an unsaturated mixture containing compounds (a1) and (a2) in a solvent in the presence of a polymerization initiator.

[0084] Compound (a1) is a radically polymerizable unsaturated carboxylic acid and / or unsaturated carboxylic acid anhydride, and examples thereof include monocarboxylic acids, dicarboxylic acids, anhydrides of dicarboxylic acids, mono[(meth)acryloyloxyalkyl] esters of polycarboxylic acids, mono(meth)acrylates of polymers having carboxy groups and hydroxyl groups at both ends, polycyclic compounds having carboxy groups, and anhydrides thereof.

[0085] Examples of unsaturated compounds having an oxiranyl group include glycidyl (meth)acrylate, α-ethyl glycidyl (meth)acrylate, α-n-propyl glycidyl (meth)acrylate, α-n-butyl glycidyl (meth)acrylate, 3,4-epoxybutyl (meth)acrylate, 6,7-epoxyheptyl (meth)acrylate, α-ethyl-6,7-epoxyheptyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, and p-vinylbenzyl glycidyl ether. Among these, glycidyl methacrylate, 6,7-epoxyheptyl methacrylate, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether, 3,4-epoxycyclohexyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, and the like are preferred from the viewpoints of improving copolymerization reactivity and the heat resistance and chemical resistance of the resulting layer. Examples of the oxetanyl group-containing unsaturated compound include compounds in which the oxiranyl group of the unsaturated compound having an oxiranyl group is substituted with an oxetanyl group.

[0086] In copolymer (a12), the ratio of the mass of the structural units derived from compound (a2) to the mass of the structural units derived from compound (a1) ((a2) / (a1)) is preferably 1 or more, more preferably 1.1 or more, and even more preferably 1.2 or more. When (a2) / (a1) is within the above range, a composition having high low-temperature storage stability and capable of long-term storage can be easily obtained, and a layer having excellent heat resistance, chemical resistance, etc. can be easily obtained.

[0087] The content of the structural units derived from compound (a2) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, based on 100% by mass of all structural units constituting copolymer (a12). When the content of the structural unit is within the above range, a composition having high low-temperature storage stability and capable of long-term storage can be easily obtained, and a layer having excellent heat resistance, chemical resistance, etc. can be easily obtained.

[0088] The copolymer (a12) may contain, in addition to the compounds (a1) and (a2), a structural unit derived from another unsaturated compound (a3) ​​copolymerizable therewith.

[0089] The compound (a3) ​​is not particularly limited as long as it is an unsaturated compound having radical polymerizability, and examples thereof include (meth)acrylic acid alkyl esters, (meth)acrylic acid cyclic alkyl esters, (meth)acrylic acid aryl esters, unsaturated dicarboxylic acid diesters, (meth)acrylic acid esters having a hydroxyl group, bicyclo unsaturated compounds, maleimide compounds, unsaturated aromatic compounds, conjugated dienes, unsaturated compounds having at least one skeleton selected from a tetrahydrofuran skeleton, a furan skeleton, a tetrahydropyran skeleton, a pyran skeleton, and a (poly)alkylene glycol skeleton, and unsaturated compounds having a phenolic hydroxyl group.

[0090] The content of the structural units derived from compound (a1) is preferably 5 to 40% by mass, and more preferably 5 to 25% by mass, relative to 100% by mass of the total of the structural units derived from compounds (a1), (a2), and (a3), in order to facilitate the formation of a layer that has excellent heat resistance and chemical resistance.

[0091] The content of the structural units derived from compound (a2) is preferably 10 to 80% by mass, and more preferably 20 to 60% by mass, relative to 100% by mass of the total of the structural units derived from compounds (a1), (a2), and (a3), in order to facilitate the formation of a layer that has excellent heat resistance and chemical resistance.

[0092] When an unsaturated compound having an alicyclic structure is used as compound (a3), the content of the structural units derived from the unsaturated compound is preferably 10 to 80% by mass, and more preferably 20 to 60% by mass, relative to 100% by mass of the total of the structural units derived from compounds (a1), (a2), and (a3), in order to facilitate the formation of a layer with superior heat resistance, for example.

[0093] The weight average molecular weight Mw of the (meth)acrylic thermosetting compound in terms of polystyrene is preferably 2×10 3 ~1×10 5 , more preferably 5 × 10 3 ~5×10 4 is. The molecular weight distribution (Mw / Mn) of the (meth)acrylic thermosetting compound is preferably 5.0 or less, and more preferably 3.0 or less.

[0094] The (meth)acrylic thermosetting compound can be synthesized, for example, by polymerizing the compound (a1), the compound (a2), and the compound (a3) ​​in an appropriate solvent in the presence of a radical polymerization initiator.

[0095] [Absorbent resin layer] The absorbing resin layer can be formed by a conventionally known method using the resin and the near-infrared absorbing agent. The absorbing resin layer may be a commercially available product, such as the Lumicle series manufactured by Elmec Co., Ltd., which is a copper complex-containing resin film.

[0096] [Absorbing glass layer] The absorbing glass layer (blue glass [BG]) may be a layer (plate) containing glass and a near-infrared absorbent, which is obtained by a conventionally known method or is commercially available, such as near-infrared absorbing glass (e.g., copper phosphate glass) obtained by adding CuO or the like to phosphate-based glass or the like, or fluorophosphate-based glass (e.g., copper fluorophosphate glass), or may be a layer containing glass such as soda-lime glass, borosilicate glass, alkali-free glass, quartz glass, or sapphire glass and a near-infrared absorbent. The "phosphate-based glass" also includes silicophosphate glass, in which part of the glass skeleton is composed of SiO2.

[0097] For example, commercially available copper phosphate glass or copper fluorophosphate glass may be used, and specific examples thereof include the BS series, such as BS3, BS4, BS6, BS7, BS8, BS10, BS11, BS12, BS16, and BS17, manufactured by Matsunami Glass Industry Co., Ltd.; KF-099 and K098S, manufactured by Platinum Technology Co., Ltd.; the BG series, such as BG57, BG63, and BG66, manufactured by SCHOTT; the QB89 series, manufactured by Zhejiang Crystal Optoelectronics Co., Ltd.; and the CXA series, such as CXA633 and CXA700, manufactured by HOYA Corporation.

[0098] [Additives] The absorbing resin layer may further contain additives such as an ultraviolet absorber, an antioxidant, a metal complex compound, a light stabilizer, a silane coupling agent, an adhesion promoter, a fluorescence quencher, a plasticizer, a filler, an antistatic agent, an antifouling agent, etc. In addition, when the absorbing resin layer is produced by cast molding, which will be described later, the production of the absorbing resin layer can be facilitated by adding a leveling agent or an antifoaming agent as an additive. These additives may be used alone or in combination of two or more.

[0099] These additives may be mixed with the resin when producing the absorbing resin layer, or may be added when producing the resin. The amount added may be selected appropriately depending on the desired properties, but is usually 0.01 to 5.0 parts by mass, and preferably 0.05 to 2.0 parts by mass, per 100 parts by mass of the resin.

[0100] UV absorber The ultraviolet absorber is preferably a near-ultraviolet absorber having at least one absorption maximum in the wavelength range of 300 to 420 nm. By incorporating such a near-ultraviolet absorber in addition to the near-infrared absorber, an optical filter that exhibits little incidence angle dependency even in the near-ultraviolet wavelength region can be easily obtained. Examples of near-ultraviolet absorbers include the BONASORB series (manufactured by Orient Chemical Industry Co., Ltd.), such as BONASORB UA-3701, UA3911, and UA-3912; the SEESORB series (manufactured by Shipro Kasei Co., Ltd.), such as SEESORB 709; and the Tinuvin series (manufactured by BASF), such as Tinuvin 400, Tinuvin 900, and Tinuvin PS.

[0101] Antioxidants Examples of the antioxidant include 2,6-di-t-butyl-4-methylphenol, 2,2'-dioxy-3,3'-di-t-butyl-5,5'-dimethyldiphenylmethane, and tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, the Adekastab AO series (manufactured by ADEKA Corporation), the Irganox series (manufactured by BASF) such as Irganox 1010, the Tinuvin series (manufactured by BASF) such as Tinuvin 120 and 1600, and the Chimassorb series (manufactured by BASF) such as Chimassorb 2020FDL.

[0102] [Method for forming the absorbing resin layer] The absorbing resin layer can be formed, for example, by melt molding, cast molding, spray coating, or vapor deposition, and can be produced by a method in which, after molding, a coating agent such as an antireflection agent, a hard coating agent, and / or an antistatic agent is coated, if necessary.

[0103] Melt molding The absorbing resin layer can be produced by a method of melt-molding pellets obtained by melt-kneading a resin and a near-infrared absorbent, a method of melt-molding a resin composition containing a resin and a near-infrared absorbent, or a method of melt-molding pellets obtained by removing a solvent from a resin composition containing a near-infrared absorbent, a resin, and a solvent, etc. Examples of melt-molding methods include injection molding, melt extrusion molding, and blow molding.

[0104] Cast molding The absorbing resin layer can also be produced by a method of casting a resin composition containing a near-infrared absorbent, a resin, and a solvent onto a suitable substrate and then removing the solvent; a method of casting a resin composition containing a coating agent such as an antireflection agent, a hard coating agent, and / or an antistatic agent, a near-infrared absorbent, and a resin onto a suitable substrate; or a method of casting a curable composition containing a coating agent such as an antireflection agent, a hard coating agent, and / or an antistatic agent, a near-infrared absorbent, and a curable compound onto a suitable substrate and then curing and / or drying the composition.

[0105] Examples of the substrate include a glass plate (including the absorbing glass layer), a steel belt, a steel drum, and a transparent resin (for example, a polyester film or a cyclic olefin resin film).

[0106] The absorbing resin layer can be obtained by peeling it off from the substrate, or alternatively, a laminate of the substrate and the coating film may be used as the absorbing resin layer without peeling it off from the substrate, as long as the effects of the present invention are not impaired.

[0107] Furthermore, an absorbing resin layer can be formed directly on an optical component by coating the resin composition on an optical component such as a glass plate, quartz, or transparent plastic and then drying the solvent, or by coating the curable composition on the optical component and then curing and drying it.

[0108] The amount of residual solvent in the absorbent resin layer obtained by the above method should be as small as possible. Specifically, the amount of residual solvent is preferably 3% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less, relative to 100% by mass of the absorbent resin layer. When the amount of residual solvent is within the above range, an absorbent resin layer that is resistant to deformation and changes in properties and can easily exhibit the desired functions can be obtained.

[0109] <Lamination method for each layer (lamination process)> Examples of the lamination method (lamination process) for each of the layers include a method (process) of laminating an absorbent resin layer obtained by the absorbent resin layer manufacturing method, or an absorbent glass layer obtained by a conventionally known method or a commercially available product, via a conventionally known adhesive, adhesive sheet, etc. Furthermore, when laminating absorbing resin layers together or laminating an absorbing resin layer and an absorbing glass layer, a solvent capable of dissolving the resin contained in the absorbing resin layer to be laminated can be applied to one or both adhesive surfaces, and after bonding the layers together, the solvent can be removed by drying or the like as necessary, thereby laminating absorbing resin layers together or an absorbing resin layer and an absorbing glass layer. Furthermore, a layer formed from the resin composition or curable composition can be laminated by applying the resin composition or curable composition onto a laminate in which an absorbing resin layer, an absorbing glass layer, or at least two selected from these layers have already been laminated, and then performing a drying or curing process as necessary. In addition, when performing the above lamination, an absorbent resin layer may be used in which the substrate has been previously peeled off from the absorbent resin layer with substrate obtained by the above-mentioned method for manufacturing an absorbent resin layer, or the substrate may be peeled off after each layer is laminated. The lamination process may be carried out by combining two or more methods (e.g., after laminating Layer 1 and Layer 2 via an adhesive or adhesive sheet to obtain a laminate, Layer 3 is formed by applying a composition for forming Layer 3 onto Layer 2 of the laminate).

[0110] <Dielectric multilayer film> From the viewpoint that an optical filter having a lower transmittance of near-infrared light can be easily obtained, it is preferable that the present filter has a dielectric multilayer film. When the present filter has a dielectric multilayer film, the present filter may contain one or more dielectric multilayer films. Note that the entire dielectric multilayer film exhibiting the desired optical properties (e.g., all 22 layers in Design 1 below) is referred to as one dielectric multilayer film. When the present filter has a dielectric multilayer film, the portion of the present filter other than the dielectric multilayer film will hereinafter also be referred to as the "absorption laminate."

[0111] When the present filter has a dielectric multilayer film, it is preferable that the dielectric multilayer film is provided on one side of the present filter or on both sides of the present filter. When the dielectric multilayer film is provided on one side, the production cost and ease of the present filter are excellent, and when the dielectric multilayer film is provided on both sides, the present filter has high strength and is less likely to warp. An example of a cross-sectional schematic diagram of the present filter having dielectric multilayer films on both sides is shown in Fig. 5. In Fig. 5, "10" indicates the present filter, "1" indicates near-infrared absorber 11 contained in layer 1, "2" indicates near-infrared absorber 22 contained in layer 2, "3" indicates near-infrared absorber 33 contained in layer 3, "5 and 6" indicate the dielectric multilayer films, "7 and 8" indicate intermediate layers such as adhesive layers, and λA, λB, and λC indicate light of certain wavelengths.

[0112] The dielectric multilayer film is preferably a film capable of reflecting near-infrared rays, and is desirably a film that has an average reflectance of preferably 80% or more, more preferably 90% or more, for unpolarized light incident at an angle of 5° from the perpendicular direction to the dielectric multilayer film surface in the wavelength range of 650 to 1700 nm.

[0113] In the present invention, the average reflectance for wavelengths A to B nm is a value calculated by measuring the reflectance at each wavelength from A nm to B nm in 1 nm increments, and dividing the sum of the reflectances by the number of measured reflectances (wavelength range, B-A+1). Since it is extremely difficult to measure the reflectance of unpolarized light incident from the perpendicular direction, in the present invention, the reflection characteristics of unpolarized light incident at an angle of 5° from the perpendicular direction were measured.

[0114] "Unpolarized light" refers to light that has no polarization direction bias, and is a collection of waves in which the electric field is distributed more or less uniformly in all directions. The "average transmittance of unpolarized light" may be the average value of the "average transmittance of S-polarized light" and the "average transmittance of P-polarized light." The "average reflectance of unpolarized light" may be the average value of the "average reflectance of S-polarized light" and the "average reflectance of P-polarized light."

[0115] Furthermore, the dielectric multilayer film preferably has a reflectance of 80% or more for light having a wavelength of 800 to 1200 nm that is incident at an angle of 5° from the perpendicular direction to the dielectric multilayer film surface. In particular, when using this filter in an imaging device, it is preferable to use this filter having a dielectric multilayer film having a reflectance of 80% or more for light having a wavelength of 800 to 1200 nm on the sensor (imaging element) side. The reflectance of light incident from one surface of the dielectric multilayer film is the same as the reflectance of light incident from the other surface of the dielectric multilayer film (both the front and back surfaces have the same reflectance). Specifically, the reflectance of light incident from above the dielectric multilayer film 5 in FIG. 5 is the same as the reflectance of light incident from below the dielectric multilayer film 5 in FIG. 5. As a result, for example, in FIG. 5, if a sensor (image pickup element) is located below the dielectric multilayer film 6 and the dielectric multilayer film 6 is a dielectric multilayer film having a reflectance of 80% or more for light with a wavelength of 800 to 1200 nm, even if light that cannot be absorbed by the near-infrared absorbers 22 and 33 or fluorescence is generated from the near-infrared absorber 33, the light is reflected by the dielectric multilayer film 6 and is thereby prevented from reaching the sensor (image pickup element), which is preferable because poor image quality is less likely to occur.

[0116] The dielectric multilayer film may be, for example, a laminate in which high refractive index material layers and low refractive index material layers are alternately stacked.

[0117] The high refractive index material layer may be made of a material having a refractive index of 1.7 or higher, and typically has a refractive index ranging from 1.75 to 2.5. Examples of such a material include at least one selected from titanium oxide, zirconium oxide, tantalum pentoxide, niobium pentoxide, lanthanum oxide, yttrium oxide, zinc oxide, zinc sulfide, and indium oxide.

[0118] The low refractive index material layer can be made of a material with a refractive index of less than 1.7, and typically has a refractive index in the range of 1.2 to 1.6. Examples of such materials include at least one selected from silica, alumina, lanthanum fluoride, magnesium fluoride, and sodium aluminum hexafluoride. Among these, materials with a lower refractive index are preferred, and at least one selected from silica and magnesium fluoride is preferred.

[0119] The method for laminating the high refractive index material layers and the low refractive index material layers is not particularly limited as long as a dielectric multilayer film is formed by laminating these material layers. For example, a dielectric multilayer film can be formed by alternately laminating high refractive index material layers and low refractive index material layers directly on the absorber laminate by a CVD method, a sputtering method, a vacuum deposition method, an ion-assisted deposition method, an ion plating method, or the like.

[0120] If warping occurs in the resulting optical filter when a dielectric multilayer film is formed, this can be prevented by forming a dielectric multilayer film on both sides of the optical filter, irradiating the dielectric multilayer film surface with electromagnetic waves such as ultraviolet light, etc. When irradiating with electromagnetic waves, the electromagnetic waves may be irradiated during the formation of the dielectric multilayer film, or may be irradiated separately after the formation of the dielectric multilayer film.

[0121] The thickness of each of these high-refractive index material layers and low-refractive index material layers is usually preferably 0.1λ to 0.5λ, where λ (nm) is the near-infrared wavelength to be blocked. When the thickness is within this range, the optical film thickness, calculated as λ / 4, where n×d is the product of the refractive index (n) and the film thickness (d), is approximately the same as the thickness of each of the high-refractive index material layers and low-refractive index material layers, and this tends to make it easier to control the blocking or transmission of specific wavelengths based on the relationship between the optical properties of reflection and refraction. Furthermore, each of these high refractive index material layers and low refractive index material layers may be a layer having a thickness other than 0.1λ to 0.5λ, and it is particularly preferable that such a layer having a thickness other than 0.1λ to 0.5λ is present in the 10 layers near the absorber laminate or in the outermost layer of the dielectric multilayer film.

[0122] The total number of high refractive index material layers and low refractive index material layers in the dielectric multilayer film is preferably 5 to 60 layers, and more preferably 6 to 50 layers.

[0123] <Other functional films> In this filter, a functional film such as an anti-reflection film, a hard coat film or an anti-static film may be appropriately provided between the absorbing laminate and the dielectric multilayer film, on the surface of the absorbing laminate opposite to the surface on which the dielectric multilayer film is provided, or on the surface of the dielectric multilayer film opposite to the surface on which the absorbing laminate is provided, for the purpose of improving the surface hardness of the absorbing laminate or the dielectric multilayer film, improving chemical resistance, preventing static electricity and erasing scratches, etc., within a range that does not impair the effects of the present invention. When the present filter has a functional membrane, the present filter may contain one functional membrane or two or more functional membranes.

[0124] The method for forming the functional film is not particularly limited, but examples include melt molding or cast molding of coating agents such as anti-reflection agents, hard coating agents and / or anti-static agents onto the absorber laminate or dielectric multilayer film in the same manner as described above. Alternatively, a functional film can be formed by applying a curable composition containing the coating agent or the like onto an absorber laminate or a dielectric multilayer film using a bar coater or the like, and then curing the composition by ultraviolet irradiation or the like. In addition, in order to improve the adhesion between the absorbent laminate and the functional film and / or the dielectric multilayer film, or between the functional film and the dielectric multilayer film, the surfaces of the absorbent laminate and the functional film may be subjected to surface treatment such as corona treatment or plasma treatment.

[0125] Examples of the coating agent include ultraviolet (UV) / electron beam (EB) curable resins and thermosetting resins, specifically vinyl compounds, urethane-based, urethane acrylate-based, acrylate-based, epoxy-based, and epoxy acrylate-based resins, etc. Examples of the curable composition containing these coating agents include vinyl-based, urethane-based, urethane acrylate-based, acrylate-based, epoxy-based, and epoxy acrylate-based curable compositions, etc.

[0126] The curable composition may also contain a polymerization initiator. As the polymerization initiator, a known photopolymerization initiator or a known thermal polymerization initiator may be used, and a photopolymerization initiator and a thermal polymerization initiator may also be used in combination. The polymerization initiator may be used alone or in combination of two or more kinds.

[0127] The content of the polymerization initiator in the curable composition is preferably 0.1 to 10 mass %, more preferably 0.5 to 10 mass %, and even more preferably 1 to 5 mass %, when the total amount of the curable composition is 100 mass %. When the content of the polymerization initiator is within the above range, a curable composition excellent in curing properties and handleability can be easily obtained, and a functional film such as an antireflection film, a hard coat film, or an antistatic film having a desired hardness can be easily obtained.

[0128] Furthermore, an organic solvent may be added to the curable composition as a solvent, and known organic solvents can be used as the organic solvent. Specific examples of the organic solvent include alcohols such as methanol, ethanol, isopropanol, butanol, and octanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; ethers such as ethylene glycol monomethyl ether and diethylene glycol monobutyl ether; aromatic hydrocarbons such as benzene, toluene, and xylene; and amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. These solvents may be used alone or in combination of two or more.

[0129] The thickness of the functional film is preferably 0.1 to 20 μm, more preferably 0.5 to 10 μm, and even more preferably 0.7 to 5 μm. When the thickness of the functional film is within the above range, the occurrence of unevenness in the formation of the functional film can be easily suppressed, and the total thickness of the optical filter can be reduced.

[0130] [Features of this filter] This filter overcomes the drawbacks of conventional optical filters, suppressing the generation of flare, particularly fluorescence in the near-infrared region, and exhibiting excellent visible light transmittance and low haze.

[0131] In the wavelength region of 450 to 600 nm, the average transmittance measured from the perpendicular direction of the filter is preferably 70% or more, more preferably 75% or more, and even more preferably 80% or more. Since a higher average transmittance is preferable, the upper limit is not particularly limited and may be 100%. The present filter having this average transmittance is excellent in visible light transmittance while adequately cutting light of wavelengths in the near-infrared region that are desired to be cut.

[0132] In the present invention, the average transmittance in a certain wavelength range (wavelengths A to B nm) is a value calculated by measuring the transmittance at each wavelength from A nm to B nm in 1 nm increments, and dividing the sum of the transmittances by the number of measured transmittances (wavelength range, B-A+1).

[0133] In one embodiment of the present filter, there are cases where it is desired to sufficiently cut light in the wavelength region of 700 to 1200 nm. When the present filter is used for such an application (e.g., as a near-infrared cut filter), the average transmittance in the wavelength region of 700 to 1200 nm, as measured from the vertical direction of the present filter, is preferably 1% or less, more preferably 0.1% or less, and even more preferably 0.05% or less. Since a lower average transmittance is preferable, the lower limit is not particularly limited and may be 0%. When the average transmittance for wavelengths of 700 to 1200 nm is in this range, near-infrared rays can be sufficiently blocked, and excellent color reproducibility can be achieved, which is preferable.

[0134] The scattered light intensity of the absorbing laminate (the present filter) in the wavelength region of 650 to 950 nm is preferably 300 nm·% or less, more preferably 150 nm·% or less, and even more preferably 70 nm·% or less. Since a lower scattered light intensity is preferable, the lower limit is not particularly limited and may be 0 nm·%. An absorbing laminate (the present filter) having a scattered light intensity within the above range can be said to be a filter with little haze. Specifically, the scattered light intensity is measured by the method described in the examples below.

[0135] [Optical filter applications] This filter has a wide viewing angle and excellent near-infrared blocking capabilities. Therefore, it is useful for correcting the visibility of solid-state imaging elements, such as CCD and CMOS image sensors in camera modules. It is particularly useful for solid-state imaging devices, such as digital still cameras, mobile phone cameras, digital video cameras, PC cameras, surveillance cameras, and automotive cameras, as well as sensing devices, such as televisions, car navigation systems, personal digital assistants, personal computers, video games, portable game consoles, fingerprint authentication systems, smart watches, and smart rings. [Example]

[0136] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Note that "parts" means "parts by mass" unless otherwise specified.

[0137] <Weight average molecular weight> The molecular weight of the resin was measured as the weight average molecular weight (Mw) in terms of standard polystyrene using a GPC device manufactured by Tosoh Corporation (HLC-8220 type, column: TSKgel α-M, developing solvent: THF).

[0138] <Glass transition temperature (Tg)> The glass transition temperature (Tg) of the resin was measured using a differential scanning calorimeter (DSC6200) manufactured by Hitachi High-Tech Science Corporation at a temperature increase rate of 20°C per minute under a nitrogen gas flow.

[0139] <Maximum absorption wavelength of near-infrared absorbent> A near-infrared absorbent solution prepared by dissolving 100 parts of Resin 1 (described below) and 0.01 parts of a near-infrared absorbent in methylene chloride (Tokyo Chemical Industry Co., Ltd.) was cast onto a glass substrate. After air-drying at room temperature for 3 hours, the resulting coating film was peeled off from the glass substrate. The resulting coating film was dried in an oven whose temperature was gradually increased from 70°C to 140°C, yielding a film with a thickness of 100 μm. The absorption maximum wavelength of the resulting film was measured using a spectrophotometer (U-4100) manufactured by Hitachi High-Tech Corporation.

[0140] The absorption maximum wavelength of the near-infrared absorbing glass (near-infrared absorber contained in the near-infrared absorbing glass) described below was measured using the near-infrared absorbing glass itself with a spectrophotometer (U-4100) manufactured by Hitachi High-Technologies Corporation.

[0141] <Transmittance> The transmittance in each wavelength range of the optical filters obtained in the following Examples and Comparative Examples was measured using a spectrophotometer (U-4100) manufactured by Hitachi High-Technologies Corporation. The transmittance measured from the perpendicular direction of the optical filter was measured for light that was transmitted perpendicularly through the optical filter. Specifically, as shown in Fig. 6, optical filter 310, mirror 320, and integrating sphere 330 were arranged, and light that was transmitted perpendicularly through optical filter 310 was measured.

[0142] <Reflectance> The reflectance in each wavelength range of the optical filters obtained in the following Examples and Comparative Examples was measured using a spectrophotometer (U-4100) manufactured by Hitachi High-Tech Corp., using an absolute reflectance measurement jig with an incident angle of 5°. Specifically, as shown in Figure 7, optical filter 310, mirror 320, and integrating sphere 330 were arranged, and the reflectance of light incident on optical filter 310 at an angle of 5° was measured.

[0143] <Scattered light intensity> For the absorber laminates (optical filters) obtained in the following examples or comparative examples, the haze at wavelengths of 650 to 950 nm was measured using a spectroscopic haze meter (HSP-150Vis) manufactured by Murakami Color Research Laboratory Co., Ltd., and the integrated value of the haze (nm·%) was taken as the scattered light intensity of the absorber laminate (optical filter). Specifically, the haze was measured by arranging an optical filter 310 and an integrating sphere 330 as shown in FIG. 8.

[0144] <Flare image evaluation> A dielectric multilayer film of the following design A was formed on glass manufactured by SHOTT (D263, thickness 100 μm) using an ion-assisted deposition apparatus (Sapio1300i, manufactured by Showa Shinku Co., Ltd.), thereby obtaining near-infrared-cutting glass A. After removing the near-infrared cut filter provided between the lens and the solid-state imaging element in the camera module of the smartphone FindX10 manufactured by OPPO, an optical filter with a dielectric multilayer film obtained in the following Examples or Comparative Examples was installed. Then, by soldering wiring, a camera module having a solid-state imaging element equipped with an optical filter with a dielectric multilayer film was fabricated. The fabricated camera module was again installed in the smartphone FindX10. In a darkroom, near-infrared cut glass A was placed in front of the camera of the smartphone FindX10 obtained, with the dielectric multilayer film side facing the camera. Images were taken using the smartphone FindX10 from a position 3 m away from a halogen lamp (manufactured by Osram, JS12V20W-AXS) serving as a light source. The captured image was divided into 256 levels of red, blue, and green intensities, and the area of ​​the region in the captured image where the red or blue intensity around the light source was 20 or more levels higher than the green intensity was calculated as R. フレア The area of ​​the region where the red, blue, and green intensities are more than 150 gradations apart is R 光源 When R フレア / R 光源 <0.1 is "AA", and 0.1≦R フレア / R 光源 If R is less than 0.5, it is called "BB" and if R is less than 0.5, it is called "BB". フレア / R 光源 The case of ≧0.5 was designated as “CC”.

[0145] [Table 1]

[0146] <Resin 1> 8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1] represented by the following formula (a) 2,5 .1 7,10100 parts of dodec-3-ene (hereinafter also referred to as "DNM"), 18 parts of 1-hexene (molecular weight modifier), and 300 parts of toluene (solvent for ring-opening polymerization reaction) were charged into a nitrogen-purged reaction vessel, and the solution was heated to 80°C. Next, 0.2 parts of a toluene solution of triethylaluminum (0.6 mol / L) and 0.9 parts of a toluene solution of methanol-modified tungsten hexachloride (concentration: 0.025 mol / L) were added as polymerization catalysts to the solution in the reaction vessel, and the solution was heated and stirred at 80°C for 3 hours to undergo ring-opening polymerization, yielding a ring-opened polymer solution. The polymerization conversion rate in this polymerization reaction was 97%.

[0147] [ka]

[0148] 1,000 parts of the ring-opened polymer solution thus obtained was charged into an autoclave, and 0.12 parts of RuHCl(CO)[P(C6H5)3]3 was added to the ring-opened polymer solution, and the mixture was heated under a hydrogen gas pressure of 100 kg / cm 2 The mixture was heated and stirred at a reaction temperature of 165°C for 3 hours to carry out a hydrogenation reaction.

[0149] The resulting reaction solution (hydrogenated polymer solution) was cooled, and the hydrogen gas pressure was released. The reaction solution was poured into a large amount of methanol, and the coagulated product was separated and collected. This product was then dried to obtain a hydrogenated polymer (hereinafter also referred to as "Resin 1"). The resulting Resin 1 had a weight-average molecular weight (Mw) of 137,000 and a glass transition temperature (Tg) of 165°C.

[0150] <Resin 2> Iupizeta RX-2136P (manufactured by Mitsubishi Gas Chemical Company, Inc., polycarbonate resin, weight average molecular weight (Mw): 58,000, glass transition temperature (Tg): 126°C) was designated as resin 2.

[0151] <Resin 3> Iupizeta FPC-8225 (manufactured by Mitsubishi Gas Chemical Company, Inc., polycarbonate resin, weight average molecular weight (Mw): 64,000, glass transition temperature (Tg): 156° C.) was designated as resin 3.

[0152] <Resin 4> In a reaction vessel equipped with a stirrer, 60 parts of 2,2-bis(4-hydroxyphenylpropane), 15 parts of 2-phenyl-3,3-bis(4-hydroxyphenyl)phthalimidine, 0.85 parts of p-tert-butylphenol as an end-capping agent, 22.9 parts of sodium hydroxide as an alkali, 0.41 parts of triethylbenzylammonium chloride as a polymerization catalyst, and 0.37 parts of sodium hydrosulfite as an antioxidant were charged and dissolved in 1750 parts of water (aqueous phase). Separately, 19.76 parts of terephthalic acid chloride (TPC) and 19.76 parts of isophthalic acid chloride (IPC) were dissolved in 1000 parts of methylene chloride (organic phase) (TPC:IPC = 50:50 (molar ratio)). The aqueous phase was pre-stirred, and the organic phase was added to the aqueous phase under strong stirring. Polymerization was carried out by interfacial polymerization at 15°C for 4 hours. Stirring was then stopped, and the aqueous and organic phases were separated by decantation. After removing the aqueous phase, 500 parts of methylene chloride, 2000 parts of pure water, and 2 parts of acetic acid were added to the organic phase to terminate the reaction, and the mixture was stirred at 15°C for 30 minutes. The organic phase was then washed 10 times with pure water and added to methanol to precipitate the polymer. The precipitated polymer was filtered and dried to obtain Resin 4. The resulting Resin 4 had a weight-average molecular weight (Mw) of 100.100 and a glass transition temperature (Tg) of 220°C.

[0153] <Near infrared absorber> As the near-infrared absorbing agent, the following near-infrared absorbing agents A-1 to A-11 were used.

[0154] A-1: Maximum absorption wavelength 670nm [ka]

[0155] A-2: Maximum absorption wavelength 699nm [ka]

[0156] A-3: Maximum absorption wavelength 733nm [ka]

[0157] A-4: Maximum absorption wavelength 760nm [ka]

[0158] A-5: Maximum absorption wavelength 786nm [ka]

[0159] A-6: Maximum absorption wavelength 843nm [ka]

[0160] A-7: Maximum absorption wavelength 886nm [ka]

[0161] A-8: Maximum absorption wavelength 1093nm [ka]

[0162] A-9: EXCITON P703TRI (maximum absorption wavelength 701 nm)

[0163] A-10: Maximum absorption wavelength 725nm [ka]

[0164] A-11: Maximum absorption wavelength 743nm [ka]

[0165] <Curable resin 1> 5 g of near-infrared absorber A-8, 95 g of methyl isobutyl ketone (MIBK) as a dispersion medium, and 175 g of zirconia beads with a diameter of 0.05 mm ("YTZ-0.05" manufactured by Nikkato Corporation) were placed in a plastic container and dispersed for 1 hour using a paint shaker. After that, the container was cooled to room temperature, and the zirconia beads were filtered off using a metal mesh to obtain an organic pigment dispersion. In a separately prepared container, 100 g of tricyclodecane dimethanol diacrylate, 3 g of 1-hydroxycyclohexyl phenyl ketone, 50 g of the obtained organic pigment dispersion, and 117 g of isopropyl alcohol were mixed to obtain a curable resin composition (hereinafter also referred to as "curable resin 1").

[0166] <Optical adhesive composition 1> Optical adhesive composition 1 (hereinafter also referred to as "OCR1") was obtained by mixing 90 g of methyl ethyl ketone, 7.5 g of Rikaresin HBE-100 (manufactured by New Japan Chemical Co., Ltd.), and 2.5 g of Fujicure FXR1030 (manufactured by T&K TOKA Corporation).

[0167] <Optical adhesive composition 2> Optical adhesive composition 2 (hereinafter also referred to as "OCR2") was obtained by mixing 96.5 g of pure water, 3.0 g of Kuraray Poval 25-88K (manufactured by Kuraray Co., Ltd.), and 5 g (1.5 g in solid content) of Sumirez Resin 650 (manufactured by Taoka Chemical Co., Ltd.).

[0168] [Example 1] 100 parts of Resin 1, 0.8 parts of near-infrared absorber A-1, and cyclopentanone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a container to obtain a solution with a resin concentration of 15 mass %. The resulting solution was then cast onto a smooth PET plate, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 20°C for 1 hour, and then dried at 120-140°C for 3 hours to form a 5 μm thick layer 1-1.

[0169] Separately, 100 parts of Resin 2, 0.4 parts of near-infrared absorber A-2, and methylene chloride were added to a container to obtain a solution with a resin concentration of 20 mass %. The resulting solution was then cast onto a smooth PET plate, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 20°C for 1 hour, and then at 120-140°C for 8 hours to form a layer 2-1 having a thickness of 10 μm.

[0170] Separately, 100 parts of Resin 1, 0.03 parts of near-infrared absorber A-3, and methylene chloride were added to a container to obtain a solution with a resin concentration of 20 mass %. The resulting solution was then cast onto a smooth PET plate, dried at 20° C. for 1 hour, and then dried at 120 to 140° C. for 2 hours to form a layer 3-1 having a thickness of 100 μm.

[0171] An optical adhesive sheet (MHM-FWD25, manufactured by Nichiei Shinka Co., Ltd.) was laminated onto Layer 1-1, and then the PET plate was peeled off from Layer 1-1. Next, Layer 2-1 was laminated onto the surface of the optical adhesive sheet, and the PET plate was peeled off from Layer 2-1, thereby obtaining a laminated film 1A in which three layers, Layer 1-1, optical adhesive sheet (intermediate layer 1), and Layer 2-1, were laminated. Hereinafter, the optical adhesive sheet (MHM-FWD25, manufactured by Nichiei Shinka Co., Ltd.) will also be referred to as "OCA1." Then, OCA1 (optical adhesive sheet, intermediate layer 2) was bonded onto layer 3-1. Layer 2-1 of laminated film 1A was bonded to the surface of OCA1. Next, the PET plate was peeled off from layer 3-1 to obtain an absorber laminate 1 (optical filter).

[0172] The evaluation results of each physical property of the absorber laminate 1 are shown in Table 6. Moreover, the spectral transmittance curve and the spectral reflectance curve of the absorber laminate 1 are shown in Fig. 9, and the spectral haze curve is shown in Fig. 10. Here, the one-side reflectance in Fig. 9 is the reflectance of the layer 1 (layer 1-1) surface of the absorber laminate 1, and the reflectance of the other surface (layer 3-1) of the absorber laminate 1 is called the two-side reflectance. The one-side reflectance of the absorber laminate in the following examples and comparative examples also refers to the reflectance of the layer 1 surface, and the reflectance of the other surface opposite to the one surface of the absorber laminate is called the two-side reflectance. Note that, since the one-side reflectance and the two-side reflectance were almost the same in the absorber laminate 1 and the absorber laminates in the following examples and comparative examples, for clarity, only the spectral reflectance curve of the one-side reflectance of each absorber laminate is shown in the figures. The absorber laminate 1 was an optical filter with excellent visible light transmittance and little haze (low scattered light intensity).

[0173] A dielectric multilayer film of Design 1 below was formed on Layer 1 (Layer 1-1) (first side) of the obtained absorber laminate 1, and a dielectric multilayer film of Design 2 below was formed on Layer 3 (Layer 3-1) (second side) of the obtained absorber laminate 1, using an ion-assisted deposition apparatus (Sapio1300i, manufactured by Showa Vacuum Co., Ltd.), thereby obtaining an optical filter 1 with a dielectric multilayer film. The evaluation results of each physical property of the optical filter 1 with a dielectric multilayer film are shown in Table 6. The spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the optical filter 1 with a dielectric multilayer film are shown in Figure 11. The optical filter 1 with a dielectric multilayer film had transmittance characteristics that were optimal for luminosity correction, and was an optical filter that produced little flare.

[0174] [Table 2]

[0175] [Table 3]

[0176] [Example 2] 100 parts of Resin 1, 0.6 parts of near-infrared absorber A-2, and cyclopentanone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a container to obtain a solution with a resin concentration of 15 mass %. The resulting solution was then cast onto a smooth PET plate, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 20°C for 1 hour, and then at 120-140°C for 3 hours to form a layer 1-2 with a thickness of 7 μm.

[0177] Separately, 100 parts of Resin 1, 0.075 parts of near-infrared absorber A-3, and methylene chloride were added to a container to obtain a solution with a resin concentration of 20 mass %. The resulting solution was then cast onto a smooth PET plate, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 20°C for 1 hour, and then at 120-140°C for 8 hours to form a layer 2-2 with a thickness of 40 μm.

[0178] Separately, 100 parts of Resin 3, 1 part of Near-Infrared Absorbent A-4, and methylene chloride were added to a container to obtain a solution with a resin concentration of 20 mass %. The resulting solution was then cast onto a smooth PET plate, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 20°C for 1 hour, and then at 120-140°C for 2 hours to form a layer 3-2 having a thickness of 5 μm.

[0179] Separately, 100 parts of Resin 1 and methylene chloride were added to a container to obtain a solution with a resin concentration of 20 mass %. The resulting solution was then cast onto a smooth PET plate, dried at 20°C for 1 hour, and then dried at 120-140°C for 2 hours to form another layer-2 having a thickness of 100 µm.

[0180] After OCA1 (optical adhesive sheet) was laminated onto Layer 1-2, the PET plate was peeled off from Layer 1-2. Next, Layer 2-2 was laminated onto the surface of OCA1, and the PET plate was peeled off from Layer 2-2, to obtain a laminated film 2A having three layers laminated together: Layer 1-2, OCA1 (intermediate layer 1), and Layer 2-2. Furthermore, OCA1 (optical adhesive sheet) was laminated onto the other layer-2, and then the PET plate was peeled off from the other layer-2. Next, layer 3-2 was laminated onto the OCA1 surface, and the PET plate was peeled off from layer 3-2, thereby obtaining a laminated film 2B in which three layers, other layer-2, OCA1 (intermediate layer 3), and layer 3-2, were laminated. Thereafter, the laminate films 2A and 2B were laminated using OCA1 (optical adhesive sheet, intermediate layer 2) so that layer 2-2 of laminate film 2A and layer 3-2 of laminate film 2B were in contact with each other, thereby obtaining an absorber laminate 2 (optical filter). The evaluation results of each physical property of the absorber laminate 2 are shown in Table 6. The spectral transmittance curve and spectral reflectance curve of the absorber laminate 2 are shown in Fig. 12, and the spectral haze curve is shown in Fig. 13.

[0181] Furthermore, in the same manner as in Example 1, the dielectric multilayer film of Design 1 was formed on Layer 1 (Layer 1-2) (first surface) of the obtained absorber laminate 2, and the dielectric multilayer film of Design 2 was formed on another layer (Another Layer-2) (second surface) of the obtained absorber laminate 2, thereby obtaining an optical filter 2 with a dielectric multilayer film. Table 6 shows the evaluation results of each physical property of the optical filter 2 with a dielectric multilayer film. Furthermore, Fig. 14 shows the spectral transmittance curve and spectral reflectance curve (first surface reflectance and second surface reflectance) of the optical filter 2 with a dielectric multilayer film.

[0182] [Example 3] Layers 1 to 3 and other layers (hereinafter also referred to as "layers 1-3 to 3-3 and other layer-3," respectively) were formed in the same manner as in Example 2, except that the type of resin, the type and amount of near-infrared absorber used, and the thickness of each layer were changed as shown in Table 6.

[0183] Using a lab coater (automatic film applicator, manufactured by Yasuda Seiki Seisakusho, Model No. 542-AB) and a coater bar (ROD No. 3), the OCR1 was applied to the formed layer 1-3 to a thickness of 0.1 μm. The OCR1 surface was then laminated to layer 2-3, and the resulting mixture was dried at 60°C for one week using an inert oven (inert oven DN410I, manufactured by Yamato Scientific Co., Ltd.). The PET plate was then peeled off from layer 2-3 to obtain laminated film 3A, which was composed of a PET plate, layer 1-3, OCR1 (intermediate layer 1), and layer 2-3. Furthermore, using a lab coater (automatic film applicator, manufactured by Yasuda Seiki Seisakusho, Model No. 542-AB) and a coater bar (ROD No. 3), the OCR1 was applied to the formed layer 4-3 to a thickness of 0.1 μm. The OCR1 surface was then laminated to layer 3-3, and the resulting mixture was dried at 60°C for one week using an inert oven (inert oven DN410I, manufactured by Yamato Scientific Co., Ltd.). The PET plate was then peeled off from layers 3-3 and 4-3, yielding a laminated film 3B in which layer 3-3, OCR1 (intermediate layer 3), and other layers 3 were laminated. Then, using a lab coater (automatic film applicator, manufactured by Yasuda Seiki Seisakusho, Model No. 542-AB) and a coater bar (ROD No. 3), the OCR1 was applied to layer 3-3 of laminate film 3B to a thickness of 0.1 μm. The OCR1 surface was then laminated to layer 2-3 of laminate film 3A, and the resulting laminate was dried at 60°C for one week using an inert oven (inert oven DN410I, manufactured by Yamato Scientific Co., Ltd.). The PET plate was then peeled off from layer 1-3, yielding an absorber laminate 3 (optical filter) consisting of layer 1-3, OCR1 (intermediate layer 1), layer 2-3, OCR1 (intermediate layer 2), layer 3-3, OCR1 (intermediate layer 3), and another layer 3. The evaluation results for each physical property of the absorber laminate 3 are shown in Table 6. The spectral transmittance curve and spectral reflectance curve of the absorber laminate 3 are shown in Figure 15.

[0184] Furthermore, in the same manner as in Example 2, the dielectric multilayer film of Design 1 was formed on Layer 1 (Layer 1-3) of the obtained absorber laminate 3, and the dielectric multilayer film of Design 2 was formed on another layer (Another Layer-3) of the obtained absorber laminate 3, to obtain an optical filter 3 with a dielectric multilayer film. Table 6 shows the evaluation results of each physical property of the optical filter 3 with a dielectric multilayer film. Furthermore, Fig. 16 shows the spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the optical filter 3 with a dielectric multilayer film.

[0185] [Example 4] An absorber laminate 4 (optical filter) and a dielectric multilayer film-coated optical filter 4 were obtained in the same manner as in Example 1, except that in Example 1, the type of resin, the amount of near-infrared absorber used, and the thickness of each layer were changed as shown in Table 6, and an optical adhesive sheet (Panaclean PDS1T8A, manufactured by PANAC Corporation) was used instead of OCA1 (optical adhesive sheet). The evaluation results of each physical property of the absorber laminate 4 and the dielectric multilayer film-coated optical filter 4 are shown in Table 6. The spectral transmittance curve and spectral reflectance curve of the absorber laminate 4 are shown in FIG. 17, and the spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the dielectric multilayer film-coated optical filter 4 are shown in FIG. In the following, the optical adhesive sheet (Panaclean PDS1T8A, manufactured by Panac Corporation) will also be referred to as "OCA2."

[0186] [Example 5] In Example 2, the type of resin, the amount of near-infrared absorber used, and the thickness of each layer were changed as shown in Table 6. A near-infrared absorbing glass (BG66, manufactured by SCHOTT Corporation, maximum absorption wavelength 855 nm, thickness 200 μm) was used as Layer 4-4 instead of Layer 2. An optical adhesive sheet (Clearfit VegaU, manufactured by Mitsubishi Chemical Corporation) was used instead of OCA1 (optical adhesive sheet) when bonding Layer 1 to Layer 2 and Layer 2 to Layer 3. An absorber laminate 5 (optical filter) and an optical filter 5 with a dielectric multilayer film were obtained in the same manner as in Example 2. The evaluation results for each physical property of the absorber laminate 5 and the optical filter 5 with a dielectric multilayer film are shown in Table 6. The spectral transmittance and spectral reflectance curves of the absorber laminate 5 are shown in FIG. 19 , the spectral haze curve is shown in FIG. 20 , and the spectral transmittance and spectral reflectance curves (single-side reflectance and two-side reflectance) of the optical filter 5 with a dielectric multilayer film are shown in FIG. 21 . In the following, the optical adhesive sheet (Clearfit VegaU, manufactured by Mitsubishi Chemical Corporation) will also be referred to as "OCA3."

[0187] [Example 6] 100 parts of Resin 1, 0.4 parts of near-infrared absorber A-2, and cyclopentanone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a container to obtain a solution with a resin concentration of 15 mass %. The resulting solution was then cast onto a smooth PET plate, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 20°C for 1 hour, and then at 120-140°C for 3 hours to form a layer 1-6 having a thickness of 10 μm.

[0188] Separately, 100 parts of Resin 1, 0.4 parts of near-infrared absorber A-6, and methylene chloride were added to a container to obtain a solution with a resin concentration of 20 mass %. The resulting solution was then cast onto a smooth PET plate, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 20°C for 1 hour, and then at 120-140°C for 8 hours to form a layer 2-6 having a thickness of 14 μm.

[0189] Separately, 100 parts of Resin 1, 1.2 parts of Near-Infrared Absorbent A-9, and methylene chloride were added to a container to obtain a solution with a resin concentration of 20 mass %. The resulting solution was then cast onto a smooth PET plate, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 20°C for 1 hour, and then dried at 120-140°C for 2 hours to form a 5 μm thick layer 4-6.

[0190] As the PET plate-attached layer 3, a PET plate-attached layer 3-6 obtained as follows was used. Curable resin 1 was cast onto a smooth PET plate, dried at 80°C for 1 hour, and then cured at 160°C for 15 minutes to form a layer 3-6 having a thickness of 2.5 µm (PET plate-attached layer 3-6 was formed).

[0191] Using a lab coater (automatic film applicator, manufactured by Yasuda Seiki Seisakusho, Model No. 542-AB) and a coater bar (ROD No. 10), the OCR2 was applied to the formed layer 1-6 to a thickness of 0.6 μm. The OCR2 surface was then laminated to layer 2-6, and the resulting mixture was dried at 140° C. for 15 minutes using an inert oven (inert oven DN410I, manufactured by Yamato Scientific Co., Ltd.). The PET plate was then peeled off from layers 1-6 and 2-6 to obtain a laminated film 6A in which layer 1-6, OCR2 (intermediate layer 1), and layer 2-6 were laminated. Furthermore, OCA1 (optical adhesive sheet) was laminated onto Layer 4-6, and then the PET plate was peeled off from Layer 4-6. Next, Layer 3-6 was laminated onto the OCA1 surface, and the PET plate was peeled off from Layer 3-6, thereby obtaining a laminated film 6B in which three layers, Layer 4-6, OCA1 (intermediate layer 3), and Layer 3-6, were laminated. Thereafter, laminate films 6A and 6B were laminated using OCA1 (optical adhesive sheet, intermediate layer 2) so that layer 2-6 of laminate film 6A and layer 4-6 of laminate film 6B were in contact with each other, thereby obtaining an absorber laminate 6 (optical filter). The evaluation results of each physical property of the absorber laminate 6 are shown in Table 6. The spectral transmittance curve and spectral reflectance curve of the absorber laminate 6 are shown in Figure 22, and the spectral haze curve is shown in Figure 23.

[0192] Furthermore, in the same manner as in Example 2, the dielectric multilayer film of Design 1 was formed on Layer 1 (Layer 1-6) of the obtained absorber laminate 6, and the dielectric multilayer film of Design 2 was formed on Layer 3 (Layer 3-6) of the obtained absorber laminate 6, to obtain an optical filter 6 with a dielectric multilayer film. Table 6 shows the evaluation results of each physical property of the optical filter 6 with a dielectric multilayer film. Furthermore, Fig. 24 shows the spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the optical filter 6 with a dielectric multilayer film.

[0193] [Example 7] 100 parts of Resin 1, 0.056 parts of near-infrared absorber A-6, and methylene chloride were added to a container to obtain a solution with a resin concentration of 20 mass %. The resulting solution was then cast onto a smooth PET plate, dried at 20° C. for 1 hour, and then dried at 120 to 140° C. for 8 hours to form a layer 2-7 having a thickness of 100 μm.

[0194] Separately, 100 parts of resin 1, 1.5 parts of near-infrared absorber A-4, 0.56 parts of near-infrared absorber A-5, and methylene chloride were added to a container to obtain a solution with a resin concentration of 20 mass%. Next, the obtained solution was cast onto the formed layer 2-7, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution, and then dried at 20°C for 1 hour, and then dried at 120 to 140°C for 8 hours to form a layer 1-7 with a thickness of 5 μm, thereby obtaining a laminate of layer 2-7 and layer 1-7.

[0195] Curable resin 1 was cast onto the surface of layer 1-7 of the resulting laminate of layers 2-7 and 1-7, dried at 80°C for 1 hour, and then cured at 160°C for 15 minutes to form layer 4-7 having a thickness of 2.5 μm. Then, curable resin 1 was cast onto the surface of layer 2-7 of the laminate on which layer 4-7 had been formed, dried at 80°C for 1 hour, and then cured at 160°C for 15 minutes to form layer 3-7 having a thickness of 2.5 μm. The laminate formed in this manner is referred to as the absorber laminate 7 (optical filter). The evaluation results of each physical property of the absorber laminate 7 are shown in Table 6. The spectral transmittance curve and the spectral reflectance curve of the absorber laminate 7 are shown in Fig. 25, and the spectral haze curve is shown in Fig. 26.

[0196] Furthermore, in the same manner as in Example 2, the dielectric multilayer film of Design 1 was formed on Layer 4 (Layer 4-7) of the obtained absorber laminate 7, and the dielectric multilayer film of Design 2 was formed on Layer 3 (Layer 3-7) of the obtained absorber laminate 7, thereby obtaining an optical filter 7 with a dielectric multilayer film. Table 6 shows the evaluation results of each physical property of the optical filter 7 with a dielectric multilayer film. Furthermore, Fig. 27 shows the spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the optical filter 7 with a dielectric multilayer film.

[0197] [Example 8] Layers 1 to 3 (hereinafter also referred to as "layers 1-8 to 3-8," respectively) were formed in the same manner as in Example 1, except that the type of resin, the type and amount of near-infrared absorber used, and the thickness of each layer were changed as shown in Table 6.

[0198] Using a lab coater (automatic film applicator, manufactured by Yasuda Seiki Seisakusho, Model No. 542-AB) and a coater bar (ROD No. 10), the OCR2 was applied to the formed layer 1-8 to a thickness of 0.6 μm. Next, the OCR2 surface was laminated to layer 2-8, and the resulting mixture was dried at 140° C. for 15 minutes using an inert oven (inert oven DN410I, manufactured by Yamato Scientific Co., Ltd.). The PET plate was then peeled off from layers 1-8 and 2-8 to obtain a laminated film 8A in which layer 1-8, OCR2 (intermediate layer 1), and layer 2-8 were laminated. Thereafter, OCA1 (optical adhesive sheet) was laminated onto Layer 2-8 of laminate film 8A, and then Layer 3-8 was laminated onto the OCA1 surface. The PET plate was peeled off from Layer 3-8 to obtain an absorber laminate 8 (optical filter) in which Layer 1-8, OCR2 (intermediate layer 1), Layer 2-8, OCA1 (intermediate layer 2), and Layer 3-8 were laminated. The evaluation results of each physical property of the absorber laminate 8 are shown in Table 6. The spectral transmittance curve and spectral reflectance curve of the absorber laminate 8 are shown in Figure 28.

[0199] Furthermore, in the same manner as in Example 1, the dielectric multilayer film of Design 1 was formed on Layer 1 (Layer 1-8) of the obtained absorber laminate 8, and the dielectric multilayer film of Design 2 was formed on Layer 3 (Layer 3-8) of the obtained absorber laminate 8, thereby obtaining an optical filter 8 with a dielectric multilayer film. Table 6 shows the evaluation results of each physical property of the optical filter 8 with a dielectric multilayer film. Furthermore, Fig. 29 shows the spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the optical filter 8 with a dielectric multilayer film.

[0200] [Example 9] A solution with a resin concentration of 15% by mass was obtained by adding 100 parts of resin 1, 0.8 parts of near-infrared absorber A-2, 1 part of near-infrared absorber A-4, and cyclopentanone (manufactured by Tokyo Chemical Industry Co., Ltd.) to a container. The resulting solution was then cast onto a smooth PET plate, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 20°C for 1 hour, and then dried at 120-140°C for 3 hours to form a 5 μm thick layer 1-9.

[0201] Separately, 100 parts of resin 1, 0.15 parts of near-infrared absorber A-3, 0.14 parts of near-infrared absorber A-5, and methylene chloride were added to a container to obtain a solution with a resin concentration of 20% by mass. The resulting solution was then cast onto a smooth PET plate, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 20°C for 1 hour, and then dried at 120-140°C for 8 hours to form a layer 2-9 having a thickness of 20 μm.

[0202] OCA1 (optical adhesive sheet) was laminated on top of layer 1-9, then layer 2-9 was laminated on the OCA1 surface, and the PET plate was peeled off from layer 2-9 to obtain laminated film 9A, which is composed of four layers: PET plate, layer 1-9, OCA1 (intermediate layer 1), and layer 2-9.

[0203] The curable resin 1 was cast onto a glass plate (manufactured by SCHOTT, D263, thickness 200 μm) as another layer-9, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 80°C for 1 hour and then cured at 160°C for 15 minutes to form a layer 3-9 with a thickness of 2.5 μm.

[0204] Using a lab coater (automatic film applicator, manufactured by Yasuda Seiki Seisakusho Co., Ltd., model number 542-AB) and a coater bar (ROD No. 3), the OCR1 (intermediate layer 2) was applied to a thickness of 0.1 μm on the surface of the glass plate (other layer-9) on which layer 3-9 was formed, opposite the surface on which layer 3-9 was formed. The OCR1 surface was then bonded to layer 2-9 of laminated film 9A, and the resulting film was dried at 60°C for one week using an inert oven (inert oven DN410I, manufactured by Yamato Scientific Co., Ltd.). The PET plate was then peeled off from layer 1-9, yielding absorber laminate 9 (optical filter). The evaluation results for each physical property of absorber laminate 9 are shown in Table 6. The spectral transmittance curve and spectral reflectance curve of absorber laminate 9 are shown in FIG. 30.

[0205] A dielectric multilayer film of Design 3 below was formed on Layer 1 (Layer 1-9) of the obtained absorber laminate 9, and a dielectric multilayer film of Design 4 below was formed on Layer 3 (Layer 3-9) of the obtained absorber laminate 9, using an ion-assisted deposition apparatus (Sapio1300i, manufactured by Showa Vacuum Co., Ltd.), thereby obtaining an optical filter 9 with a dielectric multilayer film. The evaluation results of each physical property of the optical filter 9 with a dielectric multilayer film are shown in Table 6. The spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the optical filter 9 with a dielectric multilayer film are shown in Figure 31.

[0206] [Table 4]

[0207] [Table 5]

[0208] [Example 10] In the preparation of laminated film 9A of Example 9, the type of resin, the type and amount of near-infrared absorber used, and the thickness of each layer of Layer 1 and Layer 2 (hereinafter also referred to as "Layer 1-10 and 2-10", respectively) were changed as shown in Table 6, and OCA2 (intermediate layer 1) was used to bond Layer 1 and Layer 2. A laminated film 10A was obtained in the same manner as in Example 9.

[0209] The curable resin 1 was cast onto near-infrared absorbing glass (manufactured by SCHOTT, BG66, maximum absorption wavelength 855 nm, thickness 200 μm) as layer 3-10, and the cast solution was passed through a gap formed by a smooth metal to smooth the top of the cast solution. After that, it was dried at 80°C for 1 hour and then cured at 160°C for 15 minutes to form a layer 4-10 with a thickness of 2.5 μm.

[0210] Thereafter, OCA2 (optical adhesive sheet) was attached to the surface opposite to the surface on which layer 4-10 was formed of the near-infrared absorbing glass (layer 3-10), and then layer 2-10 of laminated film 10A was attached to the surface of OCA2. The PET plate was peeled off from layer 1-10 to obtain an absorber laminate 10 (optical filter) in which layer 1-10, OCA2 (intermediate layer 1), layer 2-10, OCA2 (intermediate layer 2), layer 3-10, and layer 4-10 were laminated. The evaluation results of each physical property of the absorber laminate 10 are shown in Table 6. The spectral transmittance curve and spectral reflectance curve of the absorber laminate 10 are shown in FIG. 32, and the spectral haze curve is shown in FIG. 33.

[0211] Furthermore, in the same manner as in Example 2, the dielectric multilayer film of Design 1 was formed on Layer 1 (Layer 1-10) of the obtained absorber laminate 10, and the dielectric multilayer film of Design 2 was formed on Layer 4 (Layer 4-10) of the obtained absorber laminate 10, thereby obtaining an optical filter 10 with a dielectric multilayer film. Table 6 shows the evaluation results of each physical property of the optical filter 10 with a dielectric multilayer film. Furthermore, Fig. 34 shows the spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the optical filter 10 with a dielectric multilayer film.

[0212] [Example 11] An absorber laminate 11 (optical filter) was obtained in the same manner as in Example 2, except that the type of resin, the type of near-infrared absorber, the amount of near-infrared absorber used, and the thickness of each layer were changed as shown in Table 6, and OCA2 was used instead of OCA1 when bonding Layer 1 to Layer 2 and Layer 2 to Layer 3. The evaluation results of each physical property of the absorber laminate 11 are shown in Table 6. The spectral transmittance curve and the spectral reflectance curve of the absorber laminate 11 are shown in Fig. 35.

[0213] Furthermore, in the same manner as in Example 2, the dielectric multilayer film of Design 3 was formed on Layer 1 (first surface) of the obtained absorber laminate 11, and the dielectric multilayer film of Design 2 was formed on the other layer (second surface) of the obtained absorber laminate 11, thereby obtaining an optical filter 11 with a dielectric multilayer film. Table 6 shows the evaluation results of each physical property of the optical filter 11 with a dielectric multilayer film. Furthermore, Fig. 36 shows the spectral transmittance curve and spectral reflectance curve (first surface reflectance and second surface reflectance) of the optical filter 11 with a dielectric multilayer film.

[0214] [Comparative Example 1] An absorber laminate C1 (optical filter) and a dielectric multilayer film-coated optical filter C1 were obtained in the same manner as in Example 3, except that the type and amount of near-infrared absorber used and the thickness of each layer were changed as shown in Table 7, and layer 3 and other layers were not used. Table 7 shows the evaluation results of the physical properties of the absorber laminate C1 and the dielectric multilayer film-coated optical filter C1. The spectral transmittance curve and spectral reflectance curve of the absorber laminate C1 are shown in FIG. 37, the spectral haze curve is shown in FIG. 38, and the spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the dielectric multilayer film-coated optical filter C1 are shown in FIG. 39.

[0215] Comparative Example 2 A solution with a resin concentration of 20 mass % was obtained by adding 100 parts of resin 1, 0.0075 parts of near-infrared absorber A-9, 0.028 parts of near-infrared absorber A-10, 0.03 parts of near-infrared absorber A-11, 0.029 parts of near-infrared absorber A-5, and methylene chloride to a container. The resulting solution was then cast onto a smooth PET plate, dried at 20°C for 1 hour, and then dried at 120-140°C for 8 hours to form a layer with a thickness of 200 µm. The PET plate was peeled off from the formed layer to obtain an absorbent laminate C2 (optical filter) consisting only of the layer. The evaluation results of each physical property of the absorbent laminate C2 are shown in Table 7. The spectral transmittance curve and spectral reflectance curve of the absorbent laminate C2 are shown in Figure 40, and the spectral haze curve is shown in Figure 41.

[0216] Furthermore, in the same manner as in Example 1, the dielectric multilayer film of Design 1 was formed on one surface of the obtained absorber laminate C2, and the dielectric multilayer film of Design 2 was formed on the other surface of the obtained absorber laminate C2, thereby obtaining an optical filter C2 with a dielectric multilayer film. Table 7 shows the evaluation results of each physical property of the optical filter C2 with a dielectric multilayer film. Furthermore, Figure 42 shows the spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the optical filter C2 with a dielectric multilayer film.

[0217] Comparative Example 3 A solution with a resin concentration of 20% by mass was obtained by adding 100 parts of resin 2, 0.04 parts of near-infrared absorber A-1, 0.04 parts of near-infrared absorber A-2, 0.05 parts of near-infrared absorber A-4, and methylene chloride to a container. Next, the obtained solution was cast onto a glass plate (D263 manufactured by SCHOTT, thickness 145 μm), dried at 20°C for 1 hour, and then dried at 120 to 140°C for 8 hours to form a layer with a thickness of 100 μm, thereby obtaining an absorber laminate C3 (optical filter). The evaluation results of each physical property of the absorber laminate C3 are shown in Table 7. In addition, the spectral transmittance curve and spectral reflectance curve of the absorber laminate C3 are shown in Figure 43.

[0218] Furthermore, in the same manner as in Example 1, the dielectric multilayer film of Design 1 was formed on the layer formed above of the obtained absorber laminate C3, and the dielectric multilayer film of Design 2 was formed on the glass plate of the obtained absorber laminate C3, thereby obtaining an optical filter C3 with a dielectric multilayer film. The evaluation results of each physical property of the optical filter C3 with a dielectric multilayer film are shown in Table 7. The spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the optical filter C3 with a dielectric multilayer film are shown in Figure 44.

[0219] Comparative Example 4 An absorber laminate C4 (optical filter) and a dielectric multilayer film-coated optical filter C4 were obtained in the same manner as in Example 1, except that in Example 1, the type of resin, the type and amount of near-infrared absorber used, and the thickness of each layer were changed as shown in Table 7, and a near-infrared absorbing glass (manufactured by SCHOTT Corporation, BG66, maximum absorption wavelength 855 nm, thickness 200 μm) was used as layer 2. The evaluation results of the physical properties of the absorber laminate C4 and the dielectric multilayer film-coated optical filter C4 are shown in Table 7. The spectral transmittance curve and spectral reflectance curve of the absorber laminate C4 are shown in FIG. 45, the spectral haze curve is shown in FIG. 46, and the spectral transmittance curve and spectral reflectance curve (single-side reflectance and two-side reflectance) of the dielectric multilayer film-coated optical filter C4 are shown in FIG. 47.

[0220] [Table 6]

[0221] [Table 7]

[0222] According to the present invention, an optical filter can be obtained that suppresses the occurrence of flare, particularly the occurrence of fluorescence in the near-infrared region, has excellent visible light transmittance, and has little haze (low scattered light intensity). [Industrial Applicability]

[0223] The present filter can be suitably used in digital still cameras, mobile phone cameras, digital video cameras, PC cameras, surveillance cameras, car cameras, televisions, car navigation systems, personal digital assistants, personal computers, video games, portable game consoles, fingerprint authentication systems, smart watches, smart rings, etc. [Explanation of symbols]

[0224] 1: Near infrared absorber 11 contained in layer 1 2: Near-infrared absorber 22 contained in layer 2 3: Near-infrared absorber 33 contained in layer 3 4: Near-infrared absorber 44 contained in layer 4 5 and 6: Dielectric multilayer film 7 and 8: Intermediate layer (e.g. adhesive layer) 10: Main filter 110: Lens 120: Cabinet 130: Image sensor 140: Image sensor frame 150: Circuit board 200: (conventional) optical filter 210: Near infrared absorber 220: Near-infrared absorber different from near-infrared absorber 210 310: Optical filter 320: Mirror 330: Integrating sphere λA: Light of wavelength λA (near infrared light to be absorbed) λB: Light of wavelength λB (fluorescence) λC: Light of wavelength λC (fluorescence)

Claims

1. having Layer 1, Layer 2, and Layer 3; the layer 2 is located between the layer 1 and the layer 3; The layer 1 contains a near-infrared absorber 11 having an absorption maximum wavelength of 650 to 800 nm, The layer 2 contains a near-infrared absorber 22 having an absorption maximum wavelength of 670 to 1000 nm, the layer 3 contains a near-infrared absorber 33 having an absorption maximum wavelength of 720 to 1700 nm; The absorption maximum wavelength of the near-infrared absorbent 11 is λ1 (nm), The absorption maximum wavelength of the near-infrared absorber 22 is λ2 (nm), When the absorption maximum wavelength of the near-infrared absorbent 33 is λ3 (nm), λ1<λ2<λ3 is satisfied. Optical filter.

2. 2. The optical filter according to claim 1, wherein at least one of the layers 1 to 3 is an absorbing resin layer containing a resin, and the content of the near-infrared absorbent having an absorption maximum wavelength of 650 to 1700 nm in the absorbing resin layer is 0.01 parts by mass or more relative to 100 parts by mass of the resin.

3. 3. The optical filter according to claim 2, wherein at least two of the layers 1 to 3 are absorbing resin layers containing a resin, and the content of the near-infrared absorbent having an absorption maximum wavelength of 650 to 1700 nm in the absorbing resin layer is 0.01 parts by mass or more relative to 100 parts by mass of the resin.

4. 2. The optical filter according to claim 1, wherein the side of said layer 1 relative to said layer 2 is used as the light incident side.

5. 2. The optical filter according to claim 1, wherein the average transmittance of light having a wavelength of 450 to 600 nm is 70% or more.

6. The optical filter according to claim 1 , comprising a dielectric multilayer film.

7. A solid-state imaging device comprising the optical filter according to any one of claims 1 to 6.

8. A camera module comprising the optical filter according to any one of claims 1 to 6.

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