WO2024090311A1

WO2024090311A1 - Light-absorbing composition, production method for light-absorbing composition, light absorption film, optical filter, and manufacturing method for optical filter

Info

Publication number: WO2024090311A1
Application number: PCT/JP2023/037742
Authority: WO
Inventors: 雄一郎久保
Original assignee: 日本板硝子株式会社
Priority date: 2022-10-27
Filing date: 2023-10-18
Publication date: 2024-05-02

Abstract

A light-absorbing composition according to the present invention contains: an ultraviolet ray-absorbing compound having a hydroxy group and a carbonyl group in a molecule; metal components; polyvinyl butyral; and isocyanate. At least some of the metal components are bonded to organic oxy groups.

Description

Light-absorbing composition, method for producing light-absorbing composition, light-absorbing film, optical filter, and method for producing optical filter

The present invention relates to a light-absorbing composition, a light-absorbing film, and an optical filter.

In imaging devices using solid-state imaging elements such as CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor), various optical filters are placed in front of the solid-state imaging element to obtain images with good color reproducibility. In general, solid-state imaging elements have a spectral sensitivity in a wider wavelength range than the human visual sensitivity corresponding to the visible light region. For this reason, a technology is known in which an optical filter that blocks some infrared or ultraviolet light is placed in front of the solid-state imaging element in order to bring the spectral sensitivity of the solid-state imaging element in the imaging device closer to the human visual sensitivity.

Conventionally, such optical filters have generally used a dielectric multilayer film to block infrared or ultraviolet rays. However, in recent years, optical filters with a film containing a light absorbing agent have been attracting attention. The transmittance characteristics of optical filters with a film containing a light absorbing agent are not easily affected by the angle of incidence, so good images with little change in color can be obtained even when light is incident on the optical filter at an angle in an imaging device. In addition, light absorbing optical filters that do not use a light reflecting film can suppress the occurrence of ghosts and flares caused by multiple reflections by the light reflecting film, making it easier to obtain good images in backlit conditions or when photographing night scenes. In addition, optical filters with a film containing a light absorbing agent are also advantageous in terms of making imaging devices smaller and thinner.

A light absorber formed from phosphonic acid and copper ions is known as such a light absorber. For example, Patent Document 1 describes an optical filter having a light absorbing layer containing a light absorber formed from phosphonic acid having a phenyl group or a halogenated phenyl group (phenyl-based phosphonic acid) and copper ions.

Also, Patent Document 2 describes an optical filter having a UV-IR absorbing layer capable of absorbing infrared and ultraviolet rays. The UV-IR absorbing layer contains a UV-IR absorbent formed of phosphonic acid and copper ions. In order for the optical filter to have predetermined optical properties, the UV-IR absorbing composition contains, for example, a phenyl-based phosphonic acid and a phosphonic acid having an alkyl group or a halogenated alkyl group (alkyl-based phosphonic acid).

Patent document 3 also describes an ophthalmic device that includes a vertical violet cutoff filter. The vertical violet cutoff filter sharply absorbs light with wavelengths in the range of approximately 400 nm to 450 nm.

International Publication No. 2018/088561 Japanese Patent No. 6232161 JP 2007-535708 A

The technologies described in Patent Documents 1 and 2 need to be reconsidered from the perspective of the blocking properties of light in the short wavelength region of 410 nm or less. Furthermore, the violet light vertical cutoff filter described in Patent Document 3 is thought to have a low transmittance of visible light with a wavelength of 450 nm or more. In addition, the technologies described in Patent Documents 1 to 3 need to be reconsidered in terms of cleaning of the optical filter or durability during the manufacturing process of the optical filter.

The present invention provides a light-absorbing composition, a light-absorbing film, and an optical filter that are advantageous in terms of reproducing human visual sensitivity, particularly in terms of light absorption characteristics in the short wavelength region, and that are also advantageous in terms of durability during cleaning or manufacturing processes of the optical filter.

The present invention relates to
an ultraviolet absorbing compound having a hydroxy group and a carbonyl group in the molecule;
Metal components,
Polyvinyl butyral,
Contains an isocyanate,
At least a portion of the metal component is bonded to an organic oxy group.
A light absorbing composition is provided.

The present invention also provides a method for producing a method for manufacturing a semiconductor device comprising the steps of:
an organic solvent, a UV-absorbing compound having a hydroxyl group and a carbonyl group in the molecule,
The method includes adding and mixing a compound containing a metal component, polyvinyl butyral, and an isocyanate.
A method for producing the light absorbing composition is provided.

The present invention also provides a method for producing a method for manufacturing a semiconductor device comprising the steps of:
an ultraviolet absorbing compound having a hydroxy group and a carbonyl group in the molecule;
Metal components,
A resin having a urethane bond,
At least a portion of the metal component is bonded to an organic oxy group.
A light absorbing film is provided.

The present invention also provides a method for producing a method for manufacturing a semiconductor device comprising the steps of:
An optical filter including the above light absorbing film is provided.

The present invention also provides a method for producing a method for manufacturing a semiconductor device comprising the steps of:
A method for producing an optical filter including the light absorbing film, comprising the steps of:
The manufacturing method provides a method for manufacturing an optical filter, the method including the steps of: (i) forming a first insulating film;
(i) forming the light absorbing film on an imaging element or an optical component;
(ii) forming the light absorbing film on a substrate and peeling the light absorbing film from the substrate;

The above light absorbing composition is advantageous from the viewpoint of reproducing human visual sensitivity, particularly the absorption characteristics of light in the short wavelength region, and is also advantageous from the viewpoint of durability during cleaning or manufacturing of the optical filter. In addition, the above light absorbing film and the above optical filter are advantageous from the viewpoint of reproducing human visual sensitivity, particularly the absorption characteristics of light in the short wavelength region. Furthermore, the above light absorbing film and the above optical filter are also advantageous from the viewpoint of durability, as they are less likely to be scratched when the surface is cleaned or wiped.

FIG. 1 is a cross-sectional view showing an example of a light absorbing film according to the present invention. FIG. 2A is a cross-sectional view showing an example of an optical filter according to the present invention. FIG. 2B is a cross-sectional view showing an example of an optical filter according to the present invention. FIG. 3 shows the transmission spectrum of the optical filter according to the first embodiment. FIG. 4 shows the transmission spectrum of the optical filter according to the fifth embodiment. FIG. 5 shows the transmission spectrum of the optical filter according to the seventh embodiment. FIG. 6 shows the transmission spectrum of the optical filter according to the ninth embodiment. FIG. 7 shows the transmission spectrum of the optical filter according to the eleventh embodiment. FIG. 8 shows the reflection spectrum of the optical filter according to the first embodiment. FIG. 9 shows the reflection spectrum of the optical filter according to the fifth embodiment. FIG. 10 shows the reflection spectrum of the optical filter according to the seventh embodiment. FIG. 11 shows the reflection spectrum of the optical filter according to the ninth embodiment. FIG. 12 shows the reflection spectrum of the optical filter according to the eleventh embodiment. FIG. 13 shows the transmission spectrum of a transparent glass substrate.

If an optical filter for an imaging device using a solid-state imaging element can effectively absorb light in the short wavelength region of 410 nm or less, the value of the optical filter can be further increased in terms of reproducing human visual sensitivity. According to the optical filter described in Patent Document 1, the wavelength at which the spectral transmittance is 50% in the wavelength range of 350 nm to 450 nm is less than 400 nm. According to the optical filter described in Patent Document 2, the wavelength at which the spectral transmittance is 50% in the wavelength range of 350 nm to 450 nm is in the range of approximately 390 nm to 415 nm. Based on these facts, it is difficult to say that the optical filters described in Patent Documents 1 and 2 are advantageous in terms of effectively absorbing light in the short wavelength region of 410 nm or less. The purple light vertical cutoff filter described in Patent Document 3 may be able to effectively absorb light in the short wavelength region of 410 nm or less, but the transmittance of the filter for visible light of wavelengths of 450 nm or more is considered to be low.

The inventors therefore conducted extensive research to develop a light-absorbing composition that is advantageous from the standpoint of reproducing human visual sensitivity, particularly in terms of effectively absorbing light in the short-wavelength region of wavelengths of 410 nm or less. As a result of extensive trial and error, the inventors have newly discovered that a light-absorbing composition containing a specific ultraviolet absorbing compound and a metal component is advantageous from the standpoint of effectively absorbing light in the short-wavelength region.

In addition, the present inventors have further studied whether advantageous properties can be imparted to the light absorbing composition containing the above ultraviolet absorbing compound and metal component in terms of durability during the cleaning or manufacturing process of the optical filter. For example, the optical filter may be cleaned by wiping it with a wipe or cloth such as a wiping cloth impregnated with an organic solvent such as alcohol or acetone, or with a microfiber. In addition, during the manufacturing process of the optical filter, the portion containing the light absorbing composition or the solidified product of the light absorbing composition may come into contact with another member or the like. In view of these circumstances, it is important for the light absorbing composition containing the above ultraviolet absorbing compound and metal component to have advantageous properties in terms of durability or solvent resistance regarding the mechanical strength of the surface during the cleaning or manufacturing process of the optical filter in order to increase the added value of the light absorbing composition, light absorbing film, or optical filter. For example, it is important for the light absorbing composition to have advantageous properties in terms of scratch resistance and solvent resistance during the cleaning or manufacturing process of the optical filter.

On the other hand, it is not easy to provide advantageous characteristics in terms of durability during cleaning or manufacturing of optical filters while reproducing human visual sensitivity, particularly effective absorption of light in the short wavelength region of 410 nm or less. This is because the selection of components to be added to the light absorbing composition to provide durability during cleaning or manufacturing of optical filters requires careful consideration as to whether the effective absorption of light in the short wavelength region of 410 nm or less is impaired due to interactions between the components and ultraviolet absorbing compounds, etc. From this perspective, the inventor has undergone a great deal of trial and error. As a result, the inventor has newly identified an additive component that can provide advantageous characteristics in terms of durability during cleaning or manufacturing of optical filters in the light absorbing composition containing the above ultraviolet absorbing compound and metal component without impairing effective absorption of light in the short wavelength region of 410 nm or less, and has completed the present invention.

The following describes an embodiment of the present invention. Note that the following description is an example of the present invention, and the present invention is not limited to the following embodiment.

The light-absorbing composition according to the present invention contains an ultraviolet absorbing compound having a hydroxyl group and a carbonyl group in the molecule, a metal component, polyvinyl butyral (PVB), and an isocyanate. In this specification, an isocyanate is a compound containing -N=C=O (isocyanate group) in the molecule. In addition, at least a part of the metal component is bonded to an organic oxy group. Typically, at least a part of the metal component is bonded to an oxygen atom in the organic oxy group. This makes it easy for a light-absorbing film or optical filter made using the light-absorbing composition to effectively absorb light in the wavelength region of 410 nm or less. In addition, the light-absorbing film or optical filter can exhibit high transmittance in the visible light region. For this reason, this light-absorbing composition is advantageous from the viewpoint of reproducing human visual sensitivity.

Favourable conditions for ultraviolet absorbing compounds include appropriate light absorption and transmission ranges, photochemical stability, low enough photosensitisation to have no effect within the range of use, and thermochemical stability. From this perspective, it is considered that the mechanism of light absorption of ultraviolet absorbing compounds is the use of a hydrogen transfer reaction of a hydroxyl group in a molecule due to photoexcitation (intramolecular hydrogen abstraction reaction). Examples of ultraviolet absorbing compounds that exhibit this mechanism include compounds such as hydroxybenzophenone, salicylic acid, hydroxyphenylbenzotriazole, hydroxyphenyltriazine, and substituted acrylonitrile. In hydroxybenzophenone and salicylic acid, the reaction of hydrogen transfer between the hydroxyl group and the carbonyl group contained in the molecule is involved in the absorption of ultraviolet light, etc. On the other hand, in hydroxyphenylbenzotriazole, hydroxyphenyltriazine, and substituted acrylonitrile, the reaction of hydrogen transfer between the hydroxyl group and the nitrogen atom contained in the molecule is involved in the absorption of ultraviolet light, etc. These ultraviolet absorbing compounds have a hydroxy group having an unshared electron pair in the molecule, and are therefore presumed to cause interactions such as partial complexation with the coexisting metal component or hydrogen donor. In a system such as a light absorbing composition containing an ultraviolet absorbing compound and a cured product thereof, a comparison is made between a case where an ultraviolet absorbing compound having a hydroxy group exists alone and a case where a metal component or a hydrogen donor and an ultraviolet absorbing compound having a hydroxy group exist together. According to this comparison, differences arise in optical properties such as their light absorption spectrum and their light transmission spectrum, supporting the above presumption. In particular, it has been found that a phenomenon occurs in which a part of the light absorption band at wavelengths of 300 to 500 nm shifts to the long wavelength side in a light absorbing film or an optical filter having a light absorbing film obtained by curing a light absorbing composition containing an ultraviolet absorbing compound having a hydroxy group and a carbonyl group in the molecule and a metal component. For this reason, such a light absorbing film has advantageous properties for effectively and appropriately absorbing light having a wavelength of 410 nm or less. In addition, when the light absorption band shifts to the longer wavelength side, for example, the phenomenon of the maximum absorption wavelength shifting to the longer wavelength side within the wavelength range of 300 nm to 500 nm of the transmission spectrum, or the phenomenon of the wavelength at which the transmittance is 50% (UV cutoff wavelength) shifting to the longer wavelength side may become apparent. Thus, according to the light-absorbing composition of the present invention, the light-absorbing film which is the cured product thereof, and the optical filter equipped with the light-absorbing film, the absorption characteristics inherent to the ultraviolet absorbing compound are adjusted so that light in the short wavelength region can be effectively absorbed. As a result, the spectral transmittance of such a light-absorbing film or optical filter is likely to be more appropriate when used together with a solid-state imaging device or the like.

As described above, the light-absorbing composition contains PVB and isocyanate. This makes the light-absorbing composition more likely to have advantageous properties in terms of durability during the cleaning or manufacturing process of the optical filter. In particular, the light-absorbing composition containing PVB and isocyanate is advantageous in terms of improving scratch resistance and solvent resistance during the cleaning or manufacturing process of the optical filter. Moreover, even if the light-absorbing composition contains PVB and isocyanate, this does not prevent the absorption properties inherent to the ultraviolet absorbing compound from being adjusted so that light in the short wavelength region can be effectively absorbed by the above-mentioned mechanism of action.

PVB, for example, tends to have high transparency and can have high compatibility with organic solvents and the like. In addition, PVB has high weather resistance and high light resistance, and since the light absorbing composition contains PVB, the light absorbing film and optical filter obtained from the light absorbing composition also tend to exhibit high weather resistance and light resistance. Furthermore, PVB can exhibit advantageous properties as a binder for functional components such as the above-mentioned ultraviolet absorbing compound.

PVB exhibits good adhesion to the surfaces of lenses or other optical elements and substrates such as transparent dielectric substrates. For this reason, the light absorbing composition may have advantageous properties for producing composite optical elements or optical components that combine multiple members or parts.

PVB is represented, for example, by the following structural formula: In the structural formula, k is the mole fraction [%] of structural units having vinyl butyral groups, m is the mole fraction [%] of structural units derived from vinyl alcohol and having hydroxyl groups, and n is the mole fraction [%] of structural units derived from vinyl acetate.

PVB is obtained by reacting polyvinyl alcohol (PVA) with butyraldehyde. Since it is not possible to esterify all of the vinyl groups in PVA, some of the PVB contains groups that contain hydroxyl groups.

The number average molecular weight of PVB contained in the light absorbing composition is not limited to a specific value. The number average molecular weight is, for example, 12.0 × 10 ⁴ or less. This makes it easy to form a film of the light absorbing composition, and the haze of the light absorbing film and optical filter obtained from the light absorbing composition is likely to be low. The number average molecular weight of PVB is, for example, 1.0 × 10 ⁴ or more. This makes it difficult for the light absorbing composition to shrink during curing, and the haze of the light absorbing film and optical filter obtained from the light absorbing composition is likely to be low. The number average molecular weight of PVB may be 1.2 × 10 ⁴ or more, or 1.5 × 10 ⁴ or more. The number average molecular weight of PVB may be 11.5 × 10 ⁴ or less, or 11.0 × 10 ⁴ or less. The number average molecular weight of PVB can be measured, for example, according to Japanese Industrial Standards (JIS) K7252-1:2016.

The butyralization degree of PVB is not limited to a specific value. The butyralization degree is, for example, 60 mol% or more. This makes it easy to adjust the hydrophobicity and toughness of the surface of the light-absorbing film or optical filter obtained from the light-absorbing composition to the desired level. The butyralization degree is preferably 65 mol% or more. The butyralization degree is, for example, 90 mol% or less. This makes it easy for the desired amount of hydroxyl groups to be present in the PVB. The butyralization degree is preferably 80 mol% or less. The butyralization degree of PVB is, for example, a value expressed as a percentage of the molar fraction calculated by dividing the amount of ethylene groups to which butyral groups are bonded by the total amount of ethylene groups in the main chain. This butyralization degree can be calculated, for example, by measuring the degree of acetylation and the hydroxyl group content according to a method conforming to JIS K 6728 (Testing method for polyvinyl butyral), calculating the molar fraction from the measurement results, and then subtracting the degree of acetylation and the hydroxyl group content from 100 mol%.

The content of hydroxyl groups in PVB is not limited to a specific value. The content is, for example, 10 mol% or more. As a result, as described below, a sufficient amount of hydroxyl groups is likely to be present in PVB to be subjected to a reaction with isocyanate during curing of the light absorbing composition. The content of hydroxyl groups in PVB is preferably 20 mol% or more. The content of hydroxyl groups in PVB is, for example, 50 mol% or less. As a result, the PVB is likely to contain a desired amount of butyral groups from the viewpoint of toughness. The content of hydroxyl groups in PVB is preferably 40 mol% or less. The content of hydroxyl groups can be calculated, for example, according to a method in accordance with JIS K6728 (Test method for polyvinyl butyral).

Examples of PVB are S-LEC KS-1, S-LEC KS-10, S-LEC BX-L, S-LEC BX-1, S-LEC BL-S, and S-LEC BL-1 manufactured by Sekisui Chemical Co., Ltd. S-LEC is a registered trademark. Other examples of PVB are Mobital B20H, Mobital B30T, Mobital B30H, and Mobital B45H manufactured by Kuraray Co., Ltd. Mobital is a registered trademark. In the light absorbing composition, one or more types of PVB are selected from these PVBs or are mixed and used.

The isocyanate contained in the light absorbing composition has, for example, two or more isocyanate groups in the molecule, and each isocyanate group is bonded to a carbon atom. As described above, the PVB molecule contains a hydroxyl group, and the PVB can cause a crosslinking reaction with the isocyanate. This crosslinking reaction consumes the hydroxyl group of the PVB, and a three-dimensional network structure can be formed. Specifically, as shown in the reaction formula below, a urethane bond R ¹ -NH-COO-R ² is generated by the reaction between the isocyanate group R ¹ -N=C=O and the hydroxyl group R ² -OH contained in the PVB, and crosslinking occurs. This increases the hardness of the surface of the cured product of the light absorbing composition, and advantageous mechanical properties and solvent resistance can be realized in terms of durability in the cleaning or manufacturing process of the optical filter.

The presence or absence of a urethane bond can be understood by obtaining an infrared spectrum of a sample by a method such as Fourier transform infrared spectroscopy (FT-IR) and analyzing the presence or absence or intensity of peaks characteristic of a urethane bond in the infrared spectrum. Examples of characteristic peaks include a peak derived from the stretching vibration of N-H in the range of 3450 cm ^-1 to 3000 cm ^-1 (e.g., 3290 cm ^-1 ), a peak derived from the stretching vibration of C=O (amide I) in the range of 1735 cm ^-1 to 1691 cm ^-1 (e.g., 1725 cm ^-1 and 1705 cm ^-1 ), and a peak derived from the deformation vibration of N-H (amide II) around 1530 cm ^-1 .

The isocyanate contained in the light absorbing composition is not limited to a specific isocyanate. The isocyanate is a compound having an isocyanate group in the molecule. Examples of the isocyanate are tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), phenylene diisocyanate, dinaphthalene diisocyanate, isophorone diisocyanate, and xylylene diisocyanate. Other examples of the isocyanate are trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, and trimethylhexamethylene diisocyanate. The isocyanate may be an alicyclic polyisocyanate. Examples of the alicyclic polyisocyanate are isophorone diisocyanate, dicyclohexylmethane diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, and bis(isocyanatomethyl)norbornane. The isocyanate may be an araliphatic polyisocyanate. Examples of araliphatic polyisocyanates are xylylene diisocyanate, tetramethyl xylylene diisocyanate, and ω,ω'-diisocyanate-1,4-diethylbenzene.

As described above, in the light absorbing composition, at least a part of the metal component is bonded to the organic oxy group, and the compound includes a metal component bonded to the organic oxy group. The compound containing a metal component bonded to the organic oxy group is generally a compound represented by (R ^k -O) _n -M. M represents a metal component such as a metal atom or a metal ion. The (R ^k -O) _n - group represents n organic oxy groups (or collectively referred to as organic oxy groups, the same applies hereinafter), R ^k represents an organic group containing at least a carbon atom (C) and a hydrogen atom (H), etc., and n represents the number of groups bonded or coordinated to the metal component M, and one or more organic oxy groups may be bonded or coordinated to the metal component M. The organic oxy group (R ^k -O)- may contain two or more O (oxygen), and the organic oxy group may be bonded or coordinated to the metal component M via these two or more O (oxygen). In addition, the organic group R ^k may be the same or different for each organic oxy group (R ^k -O)- to be bonded or coordinated, and a plurality of organic oxy groups may be bonded without the metal component M being interposed therebetween. The organic oxy group is not particularly limited as long as it satisfies such conditions, and may be, for example, an alkoxy group such as a methoxy group, an ethoxy group, a propyloxy group, a phenoxy group, or an alkylphenoxy group, or a vinyl group. The organic oxy group may be an organic group R ^k that contains a partial structure (group) such as an acyl group, an acetyl group, a ketone group, a vinyl group, a propionyl group, an acrylyl group, an acetoxy group, an acryloyl group, an ethyl acetate group, an ethyl acetoacetate group, an acetylacetone group, or other ester or ether. Alternatively, the organic oxy group may contain one or more groups selected from these. The metal component M may include at least one selected from the group consisting of metal components such as metal atoms and ions of, for example, Li, Na, Mg, Ca, Sr, Ba, Ge, Sn, Pb, Al, Ga, In, Tl, Zn, Cd, Cu, Ag, Au, Ni, Pd, Pt, Co, Rh, Ir, Fe, Mn, Cr, Mo, W, V, Nb, Ta, Ti, and Zr.

The arrangement of the hydroxyl group and the carbonyl group in the ultraviolet absorbing compound is not limited to a specific arrangement. In the ultraviolet absorbing compound, the hydroxyl group and the carbonyl group are preferably arranged with one to three atoms between them. This is thought to facilitate the transfer of hydrogen between the hydroxyl group and the carbonyl group in the ultraviolet absorbing compound. This effectively facilitates the shift of the light absorption band in the wavelength range of 300 to 500 nm to the longer wavelength side. As a result, the light absorbing film obtained by curing the light absorbing composition more reliably and effectively absorbs light with a wavelength of 410 nm or less.

The ultraviolet absorbing compound is not limited to a specific compound as long as it has a hydroxyl group and a carbonyl group in its molecule. The ultraviolet absorbing compound is preferably a compound that does not easily aggregate even when mixed with a metal component.

The ultraviolet absorbing compound preferably contains a benzophenone compound represented by the following formula (A1). In this case, the light absorbing film or optical filter produced using the light absorbing composition is more likely to effectively absorb light in the short wavelength region of 410 nm or less.

In formula (A1), at least one of R ₁₁ , R ₁₂ , R ₂₁ , and R ₂₂ is a hydroxy group. In formula (A1), when R ₁₁ , R ₁₂ , R ₂₁ , or R ₂₂ is a functional group other than a hydroxy group, a plurality of R ₁₁ , a plurality of R ₁₂ , a plurality of R ₂₁ , or a plurality of R ₂₂ may be present, and at least one of R ₁₁ , R ₁₂ , R ₂₁ , and R ₂₂ may not be present.

When R ₁₁ , R ₁₂ , R ₂₁ , or R ₂₂ is a functional group other than a hydroxy group, the functional group is, for example, a carboxyl group, an aldehyde group, a halogen atom, an alkyl group having 1 to 12 carbon atoms, an alkyl group having 1 to 12 carbon atoms in which one or more hydrogen atoms are substituted with halogen atoms, an alkoxy group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms in which one or more hydrogen atoms are substituted with halogen atoms.

More preferably, the ultraviolet absorbing compound contains a benzophenone compound represented by the following formula (A2). In this case, the light absorbing film or optical filter produced using the light absorbing composition is more likely to effectively absorb light in the short wavelength region of 410 nm or less.

In formula (A2), R ₃₁ is a hydrogen atom, a hydroxyl group, a carboxyl group, an aldehyde group, a halogen atom, a group having a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. In formula (A2), R ₄₁ and R ₄₂ may be a hydroxyl group, a carboxyl group, an aldehyde group, a group having a halogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R ₄₁ and R ₄₂ may not be present. In formula (A2), a plurality of R ₄₁ may be present, and a plurality of R ₄₂ may be present. The group having a halogen atom may be a halogenated alkyl group in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom. The group having a halogen atom may be a halogenated aryl group in which at least one hydrogen atom in the aryl group is substituted with a halogen atom. The group having a halogen atom may be a halogenated alkoxy group in which at least one hydrogen atom in the alkoxy group is substituted with a halogen atom.

The benzophenone compound represented by formula (A1) or formula (A2) is not limited to a specific compound. The benzophenone compound is, for example, at least one selected from the group consisting of 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4'-chlorobenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-n-octoxybenzophenone, 2-hydroxy-5-chlorobenzophenone, and 2,4-dibenzoylresorcinol.

The ultraviolet absorbing compound may contain a salicylic acid compound represented by the following formula (B). In this case, the light absorbing film or optical filter produced using the light absorbing composition is more likely to effectively absorb light in the short wavelength region around 410 nm.

In formula (B), R ₅₁ may be a hydroxy group, a carboxy group, a group containing a halogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. In formula (B), a plurality of R ₅₁ may be present, or R ₅₁ may not be present. In formula (B), R ₅₂ is a hydrogen atom, an aryl group, or a halogenated aryl group in which one or more hydrogen atoms are substituted with halogen atoms. The group having a halogen atom may be a halogenated alkyl group in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom. The group having a halogen atom may be a halogenated aryl group in which at least one hydrogen atom in the aryl group is substituted with a halogen atom. The group having a halogen atom may be a halogenated alkoxy group in which at least one hydrogen atom in the alkoxy group is substituted with a halogen atom.

The salicylic acid compound represented by formula (B) is not limited to a specific compound. The salicylic acid compound represented by formula (B) includes, for example, at least one selected from the group consisting of phenyl salicylate, 4-butylphenyl salicylate, and octylphenyl salicylate.

The metal component is not limited to a specific metal component. The metal component is typically a component that does not aggregate in the light absorbing composition and the light absorbing film produced using the light absorbing composition, and is thermally and chemically stable. In addition, the metal component is typically a component that can interact with the ultraviolet absorbing compound.

The metal component includes at least one selected from the group consisting of, for example, Li, Na, Mg, Ca, Sr, Ba, Ge, Sn, Pb, Al, Ga, In, Tl, Zn, Cd, Cu, Ag, Au, Ni, Pd, Pt, Co, Rh, Ir, Fe, Mn, Cr, Mo, W, V, Nb, Ta, Ti, and Zr. In this case, the metal component is likely to interact with the above-mentioned ultraviolet absorbing compound.

The content C _M of the metal component in the light-absorbing composition is not limited to a specific value. The content C _M is, for example, 0.005% to 2% by mass. This makes it easier for a light-absorbing film or optical filter produced using the light-absorbing composition to more reliably absorb light in the short wavelength region of 410 nm or less. The content C _M is preferably 0.01% to 1%, more preferably 0.01% to 0.5%, and even more preferably 0.01% to 0.3%.

The content C _UV of the ultraviolet absorbing compound in the light absorbing composition is not limited to a specific value. The content C _UV is, for example, 0.1% to 20% by mass. This makes it easier for a light absorbing film or optical filter produced using the light absorbing composition to more reliably absorb light in the short wavelength region of 410 nm or less. The content C _UV is preferably 0.1% to 15%, more preferably 0.2 to 10%, even more preferably 0.5% to 10%, and particularly preferably 1% to 10%.

In the light-absorbing composition, the ratio R _UV/M of the content of the ultraviolet absorbing compound to the content of the metal component is not limited to a specific value. The ratio R _UV/M is, for example, 5 to 300 on a mass basis. This makes it easier for a light-absorbing film or optical filter produced using the light-absorbing composition to more reliably absorb light in the short wavelength region of 410 nm or less effectively. The ratio R _UV/M is preferably 10 to 300, more preferably 20 to 300, and even more preferably 30 to 280.

In the light absorbing composition, the ratio R _I/P of the mass of isocyanate to the mass of PVB is not limited to a specific value. The ratio R _I/P is, for example, 0.05 to 3.0. This makes it easier for the surface hardness of the cured product of the light absorbing composition to be increased by the crosslinking reaction between PVB and isocyanate. The ratio R _I/P is preferably 0.05 to 3.0, more preferably 0.1 to 0.3, and even more preferably 0.2 to 3.0.

In the light-absorbing composition, the ratio R _I/UV of the mass of the isocyanate to the mass of the ultraviolet absorbing compound is not limited to a specific value. The ratio R _I/UV is, for example, 0.1 to 3.0. This makes it easier to increase the hardness of the surface of the cured product of the light-absorbing composition, and makes it easier to achieve advantageous mechanical properties and solvent resistance from the viewpoint of durability during cleaning or manufacturing of optical filters. The ratio R _I/UV is preferably 0.2 to 3.0, more preferably 0.25 to 3.0.

The method for producing the light-absorbing composition is not limited to a specific method. For example, the light-absorbing composition can be produced by a method including adding an ultraviolet-absorbing compound having a hydroxyl group and a carbonyl group in the molecule, a compound containing a metal component, polyvinyl butyral, and an isocyanate to an organic solvent and mixing them.

The light absorbing composition can be used to provide, for example, the light absorbing film 10 shown in FIG. 1. The light absorbing film 10 can be obtained, for example, by curing the light absorbing composition. The light absorbing film 10 contains an ultraviolet absorbing compound having a hydroxyl group and a carbonyl group in the molecule, a metal component, and a resin having a urethane bond. In the light absorbing film 10, at least a part of the metal component is bonded to an organic oxy group. At least a part of the metal component is bonded to an oxygen atom in the organic oxy group. This makes it easy for the light absorbing film 10 to effectively absorb light in the short wavelength region of 410 nm or less. In addition, since the light absorbing film 10 contains a resin having a urethane bond, the light absorbing film 10 is easy to have advantageous characteristics in terms of improving durability or solvent resistance in cleaning optical filters.

As described above, in the light absorbing film 10, at least a part of the metal component is bonded to the organic oxy group, and the compound includes a metal component bonded to the organic oxy group. The compound containing the metal component bonded to the organic oxy group is generally a compound represented by (R ^k -O) _n -M. M represents a metal component such as a metal atom or a metal ion. The (R ^k -O) _n - group represents n organic oxy groups (or collectively referred to as organic oxy groups, the same applies hereinafter), R ^k represents an organic group containing at least a carbon atom (C) and a hydrogen atom (H), etc., n represents the number of atoms bonded or coordinated to the metal component M, and one or more organic oxy groups may be bonded or coordinated to the metal component M. The organic oxy group (R ^k -O)- may contain two or more O (oxygen), and the organic oxy group may be bonded or coordinated to the metal component M via these two or more O (oxygen). In addition, the organic group R ^k may be the same or different for each organic oxy group (R ^k -O)- to be bonded or coordinated, and a plurality of organic oxy groups may be bonded without the metal component M being interposed therebetween. The organic oxy group is not particularly limited as long as it satisfies such conditions, and may be, for example, an alkoxy group such as a methoxy group, an ethoxy group, a propyloxy group, a phenoxy group, or an alkylphenoxy group, or a vinyl group. The organic oxy group may be an organic group R ^k that contains a partial structure (group) such as an acyl group, an acetyl group, a ketone group, a vinyl group, a propionyl group, an acrylyl group, an acetoxy group, an acryloyl group, an ethyl acetate group, an ethyl acetoacetate group, an acetylacetone group, or other ester or ether. Alternatively, the organic oxy group may contain one or more groups selected from these. The metal component M may include at least one selected from the group consisting of metal components such as metal atoms and ions of, for example, Li, Na, Mg, Ca, Sr, Ba, Ge, Sn, Pb, Al, Ga, In, Tl, Zn, Cd, Cu, Ag, Au, Ni, Pd, Pt, Co, Rh, Ir, Fe, Mn, Cr, Mo, W, V, Nb, Ta, Ti, and Zr.

In the ultraviolet absorbing compound of the light absorbing film 10, the hydroxyl group and the carbonyl group are preferably spaced apart by 1 to 3 atoms. This makes it easier to improve the light absorbing film 10's ability to absorb light in the wavelength range of 410 nm or less.

The ultraviolet absorbing compound in the light absorbing film 10 includes, for example, a benzophenone-based compound represented by the above formula (A1). This makes it easier to improve the ability of the light absorbing film 10 to absorb light in the wavelength range of 410 nm or less.

The ultraviolet absorbing compound in the light absorbing film 10 preferably contains a benzophenone-based compound represented by the above formula (A2). This makes it particularly easy to improve the ability of the light absorbing film 10 to absorb light in the wavelength range of 410 nm or less.

The ultraviolet absorbing compound in the light absorbing film 10 may contain, for example, a salicylic acid compound represented by the above formula (B). In this case, it is easy to improve the ability of the light absorbing film 10 to absorb light in the wavelength range of 410 nm or less.

The metal component in the light absorbing film 10 includes at least one selected from the group consisting of, for example, Li, Na, Mg, Ca, Sr, Ba, Ge, Sn, Pb, Al, Ga, In, Tl, Zn, Cd, Cu, Ag, Au, Ni, Pd, Pt, Co, Rh, Ir, Fe, Mn, Cr, Mo, W, V, Nb, Ta, Ti, and Zr.

In the light absorbing film 10, the ratio r _UV/M of the content of the ultraviolet absorbing compound to the content of the metal component is not limited to a specific value. The ratio r _UV/M is, for example, 5 to 300 on a mass basis. This makes it easier for the light absorbing film or optical filter produced using the light absorbing composition to more reliably absorb light in the short wavelength region of 410 nm or less effectively. The ratio r _UV/M is preferably 10 to 300, more preferably 20 to 300, and even more preferably 30 to 280.

The transmittance _T400 of the light absorbing film 10 is, for example, 5% or less. This is advantageous from the viewpoint of reproducing the visual sensitivity of the human eye. The transmittance _T400 is the transmittance at a wavelength of 400 nm in the transmission spectrum at an incident angle of 0°. The transmittance _T400 is preferably 4.5% or less, and more preferably 4% or less.

The content of the ultraviolet absorbing compound in the light absorbing film 10 is not limited to a specific value. The content is, for example, 0.1% to 90%, preferably 0.5% to 80%, and more preferably 2% to 70%, by mass.

The content of the metal component in the light absorbing film 10 is not limited to a specific value. The content is, for example, 0.005% to 5% by mass, preferably 0.01% to 4%, and more preferably 0.03% to 3%.

In the light absorbing film 10, the ratio r _I/P of the mass of isocyanate to the mass of PVB is not limited to a specific value. The ratio r _I/P is, for example, 0.05 to 3.0, preferably 0.05 to 2.5, more preferably 0.05 to 2.0, and further preferably 1.0 to 2.0.

In the light absorbing film 10, the ratio r _I/UV of the mass of the isocyanate to the mass of the ultraviolet absorbing compound is not limited to a specific value. The ratio r _I/UV is, for example, 0.1 to 3.0, preferably 0.2 to 2.8, and more preferably 0.2 to 2.5.

The thickness of the light absorbing film 10 is not limited to a specific value. The thickness of the light absorbing film 10 is, for example, 0.5 μm to 500 μm, may be 1 μm to 100 μm, or may be 1 μm to 50 μm.

In the manufacture of the light absorbing film 10, the method of curing the light absorbing composition is not limited to a specific method. For example, the conditions for curing the light absorbing composition are adjusted so that a crosslinking reaction occurs between the PVB contained in the light absorbing composition and the isocyanate. As a result, the light absorbing film 10 contains a resin having a urethane bond. For example, the light absorbing composition may be cured by heating at a predetermined temperature. In this case, the predetermined temperature is, for example, 80°C or higher, preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 140 to 180°C. This makes it easier for the light absorbing film 10 to have advantageous characteristics in terms of durability in cleaning the optical filter while preventing deterioration of the ultraviolet absorbing compound.

As shown in Figures 1 and 2A, for example,

optical filters

1a and 1b equipped with a light absorbing film 10 can be provided. The

optical filters

1a and 1b tend to effectively absorb light in the short wavelength region of 410 nm or less.

In the transmission spectrum of the

optical filters

1a and 1b at an incident angle of 0 degrees, the transmittance T ₄₁₀ at a wavelength of 410 nm is, for example, 20% or less, preferably 15% or less, and more preferably 10% or less.

In the transmission spectrum of the

optical filters

1a and 1b at an incident angle of 0 degrees, the maximum transmittance T ^M _300-380 in the wavelength range of 300 to 380 nm is, for example, 3% or less. This makes it easy for the optical filter to effectively absorb light in the wavelength range shorter than 400 nm. The maximum transmittance T ^M _300-380 is preferably 2% or less, and more preferably 1% or less.

In the transmission spectrum of the

optical filters

1a and 1b at an incident angle of 0 degrees, the wavelength at which the transmittance in the wavelength range of 300 to 520 nm is 50% is defined as the ultraviolet cutoff wavelength λ _UV . In the

optical filters

1a and 1b, for example, the condition 405 nm≦λ _UV ≦500 nm is satisfied. This makes it easier for the light absorbing film 10 to effectively absorb light in the short wavelength region around the wavelength of 410 nm, and makes it easier for light in a wavelength region that is difficult for humans to recognize to be cut in an imaging device used in combination with an imaging element. The

optical filters

1a and 1b preferably satisfy the condition 405 nm≦λ _UV ≦490 nm, and more preferably satisfy the condition 405 nm≦λ _UV ≦480 nm.

In the transmission spectrum of the

optical filters

1a and 1b at an incident angle of 0 degree, the minimum transmittance T ^m _480-600 in the wavelength range of 480 to 600 nm is, for example, 85% or more. This allows the

optical filters

1a and 1b to appropriately transmit visible light, and in an imaging device used in combination with an imaging element, it is possible to increase the light flux reaching the imaging element from the subject.

The minimum value of the transmittance T ^m _480-600 is preferably 86% or more, and more preferably 87% or more.

The transmission spectrum obtained by irradiating light having a wavelength in the range of 300 nm to 1200 nm on the

optical filters

1a and 1b at an incident angle of 0° may satisfy the following requirements (ia), (ii-a), (iii-a), (iv-a), (va), and (vi-a).
(ia) The maximum transmittance T ^M _300-380 in the wavelength range of 300 nm to 380 nm is 3% or less.
(ii-a) The transmittance T ₄₀₀ at a wavelength of 400 nm is 5% or less.
(iii-a) The transmittance T ₄₁₀ at a wavelength of 410 nm is 10% or less.
(iv-a) Within the wavelength range of 350 nm to 500 nm, the wavelength λ _UV [nm] at which the transmittance is 50% is within the range of 405 nm to 490 nm.
(va) The minimum transmittance T ^m _480-600 in the wavelength range of 480 to 600 nm is 85% or more.
(vi-a) The ratio T ⁰ _UV+ /T ⁰ _UV- of the transmittance T ⁰ _UV+ at a wavelength of (λ _UV +10) nm to the transmittance T ⁰ UV- at a wavelength of (λ _UV -10) _nm is 1.8 or more.

By satisfying the above requirement (i-a), the

optical filters

1a and 1b can exhibit high ultraviolet absorption properties.

By satisfying the above requirements (ii-a) and (iii-a) in addition to the requirement (ia), the

optical filters

1a and 1b can exhibit higher ultraviolet absorbing properties. In particular, the

optical filters

1a and 1b can be applied to optical filter applications that require higher ultraviolet absorbing performance. The transmittance _T400 is preferably 4% or less.

By satisfying the above requirement (iv-a), the

optical filters

1a and 1b can exhibit high ultraviolet absorption properties, and the spectrum to which the image sensor is sensitive can easily partially match the spectrum corresponding to the human visual sensitivity. The wavelength λ _UV is preferably 420 nm to 490 nm, more preferably 420 nm to 450 nm. In this case, purple fringing is easily suppressed in the obtained image. Purple fringing is a color bleeding that appears approximately purple, especially on the contours of the subject. In addition, the transmittance of light belonging to the human visible light range can be increased, making it easier to obtain a bright image.

By satisfying the above requirement (v-a), the transmittance of light in the human visible light range tends to be high, making it easier to obtain bright images. In particular, the transmittance of the wavelength range corresponding to the maximum sensitivity on the human luminosity curve tends to be high, making it easier for humans to perceive brightness when viewing an image.

By satisfying the above requirement (vi-a), the transmission spectrum in the vicinity of the wavelength λ _UV (UV cutoff wavelength) changes sharply, so that ultraviolet rays invisible to humans can be blocked more sharply and the amount of light contained in the visible light range can be increased. The ratio T ⁰ _UV+ /T ⁰ _UV- is preferably 1.9 or more, more preferably 2.0 or more, even more preferably 2.2 or more, and particularly preferably 2.4 or more.

The reflection spectrum obtained by making light in the wavelength range of 300 nm to 1200 nm incident on the

optical filters

1a and 1b at an incident angle of 5° may satisfy the following requirements (ib) and (ii-b). In addition, the reflection spectrum obtained by making light in the wavelength range of 300 nm to 1200 nm incident on the

optical filters

1a and 1b at an incident angle of 40° may satisfy the following requirements (iii-b) and (iv-b). Furthermore, the reflection spectrum obtained by making light in the wavelength range of 300 nm to 1200 nm incident on the

optical filters

1a and 1b at an incident angle of 60° may satisfy the following requirements (vb) and (vi-b).
(ib) The maximum reflectance R ⁵ _300-450 in the wavelength range of 300 nm to 450 nm is 20% or less.
(ii-b) The maximum reflectance R ⁵ _300-600 in the wavelength range of 300 nm to 600 nm is 25% or less.
(iii-b) The maximum reflectance R ⁴⁰ _300-450 in the wavelength range of 300 nm to 450 nm is 20% or less.
(iv-b) The maximum reflectance R ⁴⁰ _300-600 in the wavelength range of 300 nm to 600 nm is 25% or less.
(vb) The maximum reflectance R ⁶⁰ _300-450 in the wavelength range of 300 nm to 450 nm is 30% or less.
(vi-b) The maximum reflectance R ⁶⁰ _300-600 in the wavelength range of 300 nm to 600 nm is 35% or less.

Satisfying the above requirements (ib) to (vi-b) is extremely advantageous in terms of preventing ghosts, flares, or noise that occur when light reflected on the surfaces of the

optical filters

1a and 1b is repeatedly reflected or refracted, for example, inside the camera module or the housing, at the edges, or at the lens surface, and reaches the image sensor. This is an advantage of using a light absorbing type filter as a filter that cuts (blocks) ultraviolet rays. The maximum value ^R5 _300-450 is preferably 15% or less. The maximum value ^R40 _300-450 is preferably 15% or less. The maximum value ^R60 _300-450 is preferably 20% or less. The maximum value ^R5 _300-600 is preferably 20% or less. The maximum value ^R40 _300-600 is preferably 20% or less. The maximum value ^R60 _300-600 is preferably 25% or less.

The

optical filters

1a and 1b may satisfy the following requirements (ic), (ii-c), (iii-c), (iv-c), and (vc). The λ ³⁰ _UV [nm] in (ic) is a wavelength at which the transmittance is 50% in the range of 350 nm to 500 nm in the transmission spectrum when light in the range of 300 nm to 1200 nm is incident on the optical filter at an incident angle of 30°. The λ ⁴⁰ _UV [nm] in (ii-c) is a wavelength at which the transmittance is 50% in the range of 350 nm to 500 nm in the transmission spectrum when light in the range of 300 nm to 1200 nm is incident on the optical filter at an incident angle of 40°. The λ ⁵⁰ _UV [nm] in (iii-c) is a wavelength at which the transmittance is 50% in the range of 350 nm to 500 nm in the transmission spectrum when light in the range of 300 nm to 1200 nm is incident on the optical filter at an incident angle of 50°. The λ ⁶⁰ _UV [nm] of (iv-c) is a wavelength at which the transmittance is 50% in the range of 350 nm to 500 nm in the transmission spectrum when light in the range of 300 nm to 1200 nm is incident on the optical filter at an incident angle of 60°. The λ ⁷⁰ _UV [nm] of (vc) is a wavelength at which the transmittance is 50% in the range of 350 nm to 500 nm in the transmission spectrum when light in the range of 300 nm to 1200 nm is incident on the optical filter at an incident angle of 70°.
(ic) | λ ³⁰ _UV - λ _UV | ≦ 2.4 nm
(ii-c) | λ ⁴⁰ _UV - λ _UV | ≦ 3 nm
(iii-c) | λ ⁵⁰ _UV - λ _UV | ≦ 5 nm
(iv-c) | λ ⁶⁰ _UV - λ _UV | ≦ 9 nm
(vc) | λ ⁷⁰ _UV - λ _UV | ≦ 18 nm

Complete absorption type UV cut filters have the advantage that the angle dependency of the transmission spectrum is small. UV cut filters that cut UV rays with a reflective film made of a dielectric multilayer film tend to have a UV cutoff wavelength that shifts to the short wavelength side for light incident at an angle. For this reason, the UV light that you want to cut may be detected by the sensor depending on the angle of incidence. On the other hand,

optical filters

1a and 1b satisfy the above requirements (i-c) to (v-c), and there is little change in the UV cutoff wavelength for oblique incidence, and the UV cutoff wavelength is unlikely to shift to the short wavelength side. Therefore,

optical filters

1a and 1b, in addition to the function of suppressing ghosts and flares, make it easy to achieve good color reproducibility that is less likely to cause color unevenness within the surface, making it easy to obtain high-quality images.

The optical filter 1a is, for example, composed of a single light absorbing film 10. In this case, the optical filter 1a can be used, for example, separately from the imaging element or optical component. The optical filter 1a may be bonded to the imaging element and the optical component. On the other hand, the optical filter 1a may be constructed by applying the above-mentioned light absorbing composition to the imaging element or optical component and curing the light absorbing composition. In this way, the optical filter 1a may be manufactured by forming the light absorbing film 10 on the imaging element or optical component.

The optical filter 1a can be produced, for example, by peeling off the light absorbing film 10 formed on the substrate from the substrate. In this case, the material of the substrate may be glass, resin, or metal. The surface of the substrate may be subjected to a surface treatment such as coating with a fluorine-containing compound. In this way, the optical filter 1a may be manufactured by forming the light absorbing film 10 on the substrate and peeling off the light absorbing film 10 from the substrate.

As shown in FIG. 2A, the optical filter 1b includes a light absorbing film 10 and a transparent dielectric substrate 20. The light absorbing film 10 is provided parallel to one of the main surfaces of the transparent dielectric substrate 20. The light absorbing film 10 may be in contact with one of the main surfaces of the transparent dielectric substrate 20, for example. In this case, the light absorbing film 10 can be formed, for example, by applying the above-mentioned light absorbing composition to one of the main surfaces of the transparent dielectric substrate 20 and curing the light absorbing composition.

The type of the transparent dielectric substrate 20 is not limited to a specific type. The transparent dielectric substrate 20 may have an absorption ability in the infrared region. The transparent dielectric substrate 20 may have an average spectral transmittance of 90% or more at wavelengths of, for example, 350 nm to 900 nm. The material of the transparent dielectric substrate 20 is not limited to a specific material, but may be, for example, a specific glass or resin. When the material of the transparent dielectric substrate 20 is glass, the transparent dielectric substrate 20 may be, for example, transparent glass made of silicate glass such as soda-lime glass and borosilicate glass, or phosphate glass and fluorophosphate glass containing coloring components such as Cu and Co. Phosphate glass and fluorophosphate glass containing coloring components are, for example, infrared absorbing glass, and are themselves light absorbing. When the light absorbing film 10 is used together with the transparent dielectric substrate 20 of infrared absorbing glass, the light absorption and transmission spectrum of both can be adjusted to produce an optical filter having desired optical characteristics, and the degree of freedom in designing the optical filter is high.

When the material of the transparent dielectric substrate 20 is a resin, the resin is, for example, a cyclic olefin resin such as a norbornene resin, a polyarylate resin, an acrylic resin, a modified acrylic resin, a polyimide resin, a polyetherimide resin, a polysulfone resin, a polyethersulfone resin, a polycarbonate resin, or a silicone resin.

Each of the

optical filters

1a and 1b may be modified to further include other functional films such as an infrared absorbing film, an infrared reflecting film, and an anti-reflection film. Such functional films may be provided on the light absorbing film 10 or the transparent dielectric substrate 20. For example, the optical filter may include an anti-reflection film to increase the transmittance in a predetermined wavelength range (for example, the visible light range). The anti-reflection film may be configured as a layer of a low refractive index material such as _MgF2 and _SiO2 , or may be configured as a laminate of such a layer of a low refractive index material and a layer of a high refractive index material such as _TiO2 , or may be configured as a dielectric multilayer film. Such an anti-reflection film may be formed by a method involving a physical reaction such as vacuum deposition and sputtering, or by a method involving a chemical reaction such as CVD and sol-gel.

The optical filter may be configured, for example, with the light absorbing film 10 disposed between two sheets of glass. In this case, the light absorbing film 10 acts as a so-called intermediate film. This improves the rigidity and mechanical strength of the optical filter. In addition, the main surface of the optical filter becomes hard, which is advantageous from the standpoint of preventing scratches, etc. This advantage is particularly important when a relatively flexible resin is used as the binder or matrix in the light absorbing film 10.

By providing an anti-reflection film on the surface of the light absorbing film and optical filter obtained by curing the light absorbing composition, an optical filter with even better optical properties can be provided. For example, as shown in FIG. 2B, an optical filter 1c can be provided that includes a light absorbing film 10 and an anti-reflection film 30. In an optical filter having an anti-reflection film, when light is incident on the optical filter at a predetermined angle of incidence, the light reflected from the optical filter is reduced and approaches zero. This is extremely advantageous in an imaging device equipped with an optical filter having an anti-reflection film, from the viewpoint of preventing ghosts, flares, and noise that occur due to multiple scattering of reflected light within the imaging device or camera module, for example.

The material of the anti-reflective film is not limited to a specific material. The method of forming the anti-reflective film is not limited to a specific method. The method of forming the anti-reflective film may be a gas phase method or a liquid phase method. For example, the method of forming the anti-reflective film may be a vapor deposition method. The method of forming the anti-reflective film may be a sol-gel method using a reactive material containing silicon, which is a liquid phase method that is excellent for forming anti-reflective films.

The anti-reflective film may be a single layer film made of the same type of material, or a multilayer film made of two or more different materials. The material constituting each layer of the film and multilayer film is not limited to a specific material. The material is, for example, an inorganic compound such as SiO ₂ , TiO ₂ , Ta ₂ O ₃ , MgF ₂ , Al ₂ O ₃ , CaF ₂ , ZrO ₂ , CeO ₂ , and ZnS. For example, when the anti-reflective film or a layer contained in the anti-reflective film contains SiO ₂ , the film or layer may be formed by a so-called sol-gel method using an alkoxysilane compound as a starting material. By the sol-gel method, the alkoxysilane compound is hydrolyzed and then condensed in the presence of water and a catalyst to obtain a dense and hard film containing SiO _2. The sol-gel method has the advantage that a film or layer containing SiO ₂ can be formed without requiring high temperatures.

When forming an anti-reflective coating using the sol-gel method, the starting material is not limited to a specific material, and the functional group of the starting material is not limited to a specific functional group. The starting material preferably includes "trifunctional silanes containing alkyl groups" such as MTES (methyltriethoxysilane) and TEOS (tetraethoxysilane), and "tetrafunctional silanes". Tetrafunctional silanes are essential for forming a film or layer with a strong and dense skeleton. On the other hand, it is difficult to control the reactivity with tetrafunctional silanes alone, and it is difficult to adjust the polarity of the film or layer. In addition, cracks are likely to occur in the film or layer. If the starting material contains trifunctional silane in addition to tetrafunctional silane, the flexibility of the silica skeleton is improved, the polarity of the film or layer is easily adjusted, and cracks in the film or layer are easily suppressed. It is desirable to be able to easily adjust the polarity of the film or layer from the viewpoint of adjusting the refractive index of the anti-reflective coating. The organic functional groups in the trifunctional silanes are not originally limited to specific functional groups. In particular, trifunctional silanes that have a methyl group as an organic functional group are desirable in order to form homogeneous liquids and coatings when combined with tetrafunctional silanes.

In the starting material, the ratio of the amount of "trifunctional silane containing an alkyl group" to the amount of "tetrafunctional silane" is not limited to a specific value. Preferably, in the starting material, the relationship of the amount of "trifunctional silane containing an alkyl group" to the amount of "tetrafunctional silane" = 5:1 to 1:3 is satisfied on a mass basis. This makes it easier to suppress cracks in the anti-reflective film, and makes it easier for the tetrafunctional silane to form a strong skeleton. The starting material may contain components other than those involved in the sol-gel method. For example, the starting material may contain fine particles and fillers for adjusting the refractive index. In this case, the fine particles and fillers may be hollow or may be high refractive index materials. The starting material may contain components that decompose at low temperatures. This makes it easier to adjust the refractive index of the anti-reflective film. The temperature at which the coating film is baked in the sol-gel method is not limited to a specific temperature. The temperature is, for example, in the range of 60°C to 250°C, preferably in the range of 70°C to 230°C, and more preferably in the range of 80°C to 200°C.

When the anti-reflective film is a single-layer film, it is desirable that the material of the single-layer film has a low refractive index. The refractive index n ₁ of the material of the anti-reflective film is likely to be the smallest when n ₁ = √n _0. n ₀ is the refractive index of the substrate on which the anti-reflective film is formed. For example, when the anti-reflective film contains hollow particles formed of metal oxides such as SiO ₂ and TiO ₂ or organic materials such as PMMA, the inside of the hollow particles is occupied by air with a refractive index of about 1, so that the effective refractive index of the particles can be lowered and the refractive index of the anti-reflective film is likely to be low. The dielectric constant and refractive index of a mixture consisting of multiple phases can be obtained by an effective medium approximation method using the Bruggemann formula. When the refractive index required for the anti-reflective film is not so low, the anti-reflective film may contain solid particles formed of the above materials. When mechanical strength such as scratch resistance is required for the anti-reflective film, it is advantageous for the anti-reflective film to contain such solid particles. A film may be formed by a sol-gel method in a state containing such hollow particles or solid particles. In particular, when hollow or solid particles made of _SiO2 are used, the affinity between the _SiO2 in the film formed by the sol-gel method and the hollow or solid particles is good, and aggregation of the hollow or solid particles is suppressed, which is expected to suppress bleed-out, etc.

The anti-reflection film may have a multilayer structure including a layer containing SiO ₂ formed by a sol-gel method and a layer formed by, for example, a vacuum deposition method, a sol-gel method, or other methods. For example, by forming the anti-reflection film into a multilayer structure using two or more materials having different refractive indexes, the wavelength band in which the anti-reflection effect can be obtained is relatively wide, and the minimum value of the reflectance in the optical filter is likely to be low. When the anti-reflection film is combined with a layer containing SiO ₂ formed by a sol-gel method to form a multilayer structure, the layer to be combined may be, for example, a layer containing hollow particles and containing SiO ₂ formed by a sol-gel method, a layer made of a material having a relatively high refractive index such as TiO ₂ and Ta ₂ O ₃ , or a layer made of other materials such as MgF ₂ .

The present invention will be explained in more detail using examples. Note that the present invention is not limited to the following examples. First, the evaluation method of the optical filters in each example and each comparative example will be explained.

<Measurement of Transmission Spectrum and Reflection Spectrum>
The transmission spectrum and reflection spectrum of each optical filter at a predetermined angle of incidence were measured using an ultraviolet-visible-near infrared spectrophotometer (manufactured by JASCO Corporation, product name: V-670).

<Thickness measurement>
The distance from the surface of each optical filter was measured using a laser displacement meter (Keyence Corporation, product name: LK-H008), and the thickness of the light absorbing film was measured by subtracting the thickness of the transparent glass substrate.

<Scratch resistance test>
Kuraray Kuraclean Wiper LF-8G was soaked with ethanol, propylene glycol monomethyl ether (PGME), or propylene glycol monomethyl ether acetate (PGMEA) to obtain an alcohol-soaked wiper. The alcohol-soaked wiper was pressed against the light-absorbing film obtained in each Example and Comparative Example at a pressure of 40 to 60 g/cm ² and reciprocated 10 times over a length of about 3 cm to rub the surface of the light-absorbing film. Thereafter, the condition of the surface of the light-absorbing film was visually confirmed, and the case where there was no particular change was evaluated as "A", the case where scratches were observed on the surface was evaluated as "B", and the case where peeling of the light-absorbing film occurred was evaluated as "C". The results are shown in Table 8.

<Ultraviolet absorbing compound>
The following ultraviolet absorbing compounds were used in the production of the optical filters according to the examples and comparative examples.

The structural formulas of the ultraviolet absorbing compounds (1-1) and (1-2) are represented by the following formulas (C) and (D), respectively.

<Compounds containing metal components>
In producing the optical filters according to the examples and comparative examples, materials containing the following metal components were used.

Example 1
5.0 g of the ultraviolet absorber (1-1) shown in Table 1, 80.0 g of cyclohexanone as a solvent, and 8.0 g of polyvinyl butyral (PVB) S-LEC KS-10 (molecular weight 1.7×10 ⁴ , degree of acetalization 74 mol %, hydroxyl group content 25 mol %) manufactured by Sekisui Chemical Co., Ltd. were mixed and stirred for 30 minutes. Next, 0.308 g of the material (2-1) containing a metal component shown in Table 2 was added to the obtained mixture and stirred for 30 minutes. 4.0 g of tolylene diisocyanate (TDI) was further added to the obtained mixture and stirred for 30 seconds to obtain a light absorbing composition according to Example 1. The content of each component, the mass ratio of the predetermined components, and the substance amount ratio of the predetermined components in the light absorbing composition according to Example 1 are shown in Tables 3 and 4. Note that the content of the metal component in the material (2-1) containing a metal component was determined to be 6.5 mass %, as shown in Table 2, and the mass ratio or substance amount ratio of the components of the light-absorbing composition according to Example 1 was calculated based on this premise.

The light absorbing composition according to Example 1 was spin-coated at 500 rotations per minute (rpm) on one main surface of a transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) made of borosilicate glass having dimensions of 76 mm x 76 mm x 0.21 mm to form a coating film. The resulting coating film was thoroughly dried at room temperature, and then placed in an oven and heat-treated at 140°C for 1 hour and at 160°C for 2 hours to cause a crosslinking reaction between PVB and TDI, thereby obtaining a light absorbing film according to Example 1. In this manner, an optical filter provided with a light absorbing film according to Example 1 was produced. Figure 3 shows the transmission spectrum of the optical filter according to Example 1. Figure 8 shows the reflection spectrum of the optical filter according to Example 1. Values related to the film thickness and optical properties of the light absorbing film of the optical filter according to Example 1 are shown in Tables 5, 6, and 7. The results of the scratch resistance test of the light absorbing film according to Example 1 are shown in Table 8. Figure 13 shows the transmission spectrum of the transparent glass substrate at an incident angle of 0 degrees.

<Examples 2 to 4>
The light-absorbing compositions according to Examples 2 to 4 were prepared in the same manner as in Example 1, except that the amount of isocyanate added and/or the type of PVB were changed as shown in Table 3. The light-absorbing films and optical filters according to Examples 2 to 4 were produced in the same manner as in Example 1, except that the light-absorbing compositions according to Examples 2 to 4 were used instead of the light-absorbing composition according to Example 1. The PVB used in Example 4 was S-LEC KS-1 (molecular weight 2.7×10 ⁴ , acetalization degree 74 mol %, hydroxyl group content 25 mol %) manufactured by Sekisui Chemical Co., Ltd. Tables 5, 6, and 7 show values related to the optical properties that can be seen from the transmission spectrum and reflection spectrum of the optical filters according to Examples 2 to 4. From these results, it can be understood that good optical properties can be obtained even if the ratio of the mass of isocyanate to the mass of PVB in the light-absorbing composition varies in the range of 0.18 to 1.50. The results of the scratch resistance test of the light-absorbing films according to Examples 2 to 4 are shown in Table 8.

<Examples 5 and 6>
Light absorbing compositions according to Examples 5 and 6 were prepared in the same manner as in Example 1, except that the type of PVB and the type and amount of isocyanate added were changed as shown in Table 3. Light absorbing films and optical filters according to Examples 5 and 6 were produced in the same manner as in Example 1, except that the light absorbing compositions according to Examples 5 and 6 were used instead of the light absorbing composition according to Example 1. The PVB used in Example 5 was S-LEC BX-L (molecular weight 1.8×10 ⁴ , acetalization degree 67 mol %, hydroxyl group content 32 mol %) manufactured by Sekisui Chemical Co., Ltd., and the PVB used in Example 6 was S-LEC BX-1 (molecular weight 10×10 ⁴ , acetalization degree 72 mol %, hydroxyl group content 27 mol %) manufactured by Sekisui Chemical Co., Ltd. The isocyanate used in Example 5 was diphenylmethane diisocyanate (MDI), and the isocyanate used in Example 6 was hexamethylene diisocyanate (HDI). FIG. 4 shows the transmission spectrum of the optical filter according to Example 5. FIG. 9 shows the reflection spectrum of the optical filter according to Example 5. Tables 5, 6, and 7 show the optical property values of the optical filters according to Examples 5 and 6. According to Examples 5 and 6, it is understood that good optical properties can be obtained even if MDI or HDI is used instead of TDI. Table 8 shows the results of the scratch resistance test of the light absorbing films according to Examples 5 and 6.

<Examples 7 to 14>
Light absorbing compositions according to Examples 7 to 14 were prepared in the same manner as in Example 1, except that the type or amount of the ultraviolet absorbing compound, the material containing a metal component, the PVB, or the isocyanate was changed as shown in Table 3. Light absorbing films and optical filters according to Examples 7 to 14 were produced in the same manner as in Example 1, except that the light absorbing compositions according to Examples 7 to 14 were used instead of the light absorbing composition according to Example 1. The PVB used in Example 7 was S-LEC BX-1 manufactured by Sekisui Chemical Co., Ltd. The PVB used in Example 8 was S-LEC KS-1 manufactured by Sekisui Chemical Co., Ltd. The PVB used in Example 12 was S-LEC BL-S manufactured by Sekisui Chemical Co., Ltd. (molecular weight 2.3×10 ⁴ , acetalization degree 72 mol%, hydroxyl group content 23 mol%). The PVB used in Example 13 was S-LEC BL-1 (molecular weight 1.9×10 ⁴ , acetalization degree 63 mol %, hydroxyl group content 36 mol %) manufactured by Sekisui Chemical Co., Ltd. In Examples 9, 10, 11, and 14, S-LEC KS-10 manufactured by Sekisui Chemical Co., Ltd. was used as the PVB. Figures 5, 6, and 7 show the transmission spectra of the optical filters according to Examples 7, 9, and 11, respectively. Figures 10, 11, and 12 show the reflection spectra of the optical filters according to Examples 7, 9, and 11, respectively. Furthermore, values related to the optical properties of the optical filters according to Examples 7 to 14 are shown in Tables 5, 6, and 7. The results of the scratch resistance test of the light absorbing films according to Examples 7 to 14 are shown in Table 8.

<Comparative Example 1>
A light-absorbing composition according to Comparative Example 1 was prepared in the same manner as in Example 1, except that no isocyanate was added. A light-absorbing film and an optical filter according to Comparative Example 1 were produced in the same manner as in Example 1, except that the light-absorbing composition according to Comparative Example 1 was used instead of the light-absorbing composition according to Example 1. Values relating to the optical properties of the optical filter according to Comparative Example 1 are shown in Tables 5, 6, and 7. The results of the scratch resistance test of the light-absorbing film according to Comparative Example 1 are shown in Table 8.

The optical filters according to each of the Examples and Comparative Example 1 had good optical characteristics from the viewpoint of reproducing the visual sensitivity of humans. On the other hand, a comparison between the Examples and Comparative Examples suggested that the light-absorbing composition containing both PVB and isocyanate is likely to provide good solvent resistance and scratch resistance. In particular, it was suggested that good solvent resistance and scratch resistance are likely to be obtained when the ratio of the mass of isocyanate to the mass of PVB in the light-absorbing composition is 0.15 or more. From the viewpoint of good solvent resistance and scratch resistance, the ratio of the mass of isocyanate to the mass of PVB is preferably 0.15 or more, and more preferably 0.18 or more. It is considered that the upper limit of the ratio of the mass of isocyanate to the mass of PVB is not limited to a specific value, but from the viewpoint of suppressing the hardening of the light-absorbing composition immediately after application of the light-absorbing composition due to an increase in isocyanate, and facilitating the formation of a light-absorbing film with a flat and uniform thickness, it is considered that the ratio is preferably 1.50 or less. From the viewpoint of good optical properties, solvent resistance, and scratch resistance, it was suggested that the ratio of the mass of the isocyanate to the mass of the UV-absorbing compound is preferably 0.3 or more, and more preferably in the range of 0.3 to 2.4.

Claims

an ultraviolet absorbing compound having a hydroxy group and a carbonyl group in the molecule;
Metal components,
Polyvinyl butyral,
Contains an isocyanate,
At least a portion of the metal component is bonded to an organic oxy group.
Light absorbing composition.
The content of the metal component in the light absorbing composition is 0.005% to 2% by mass.
The light absorbing composition of claim 1 .
The content of the ultraviolet absorbing compound in the light absorbing composition is 0.1% to 20% by mass.
The light absorbing composition according to claim 1 or 2.
the ratio of the mass of the ultraviolet absorbing compound to the mass of the metal component is 5 to 300;
The light absorbing composition according to any one of claims 1 to 3.
The ratio of the mass of the isocyanate to the mass of the polyvinyl butyral is 0.05 to 3.0;
The light absorbing composition according to any one of claims 1 to 4.
the ratio of the mass of the isocyanate to the mass of the ultraviolet absorbing compound is 0.1 to 3.0;
The light absorbing composition according to any one of claims 1 to 5.
the hydroxy group and the carbonyl group are separated by 1 to 3 atoms;
The light absorbing composition according to any one of claims 1 to 6.
The ultraviolet absorbing compound includes a benzophenone-based compound represented by the following formula (A1):
The light absorbing composition according to any one of claims 1 to 7.

[In formula (A1), at least one of R 11 , R 12 , R 21 , and R 22 is a hydroxy group. In formula (A1), when R 11 , R 12 , R 21 , or R 22 is a functional group other than a hydroxy group, a plurality of R 11 , a plurality of R 12 , a plurality of R 21 , or a plurality of R 22 may be present, and at least one of R 11 , R 12 , R 21 , and R 22 may not be present.]
The ultraviolet absorbing compound includes a benzophenone-based compound represented by the following formula (A2):
The light absorbing composition according to any one of claims 1 to 8.

[In formula (A2), R 31 is a hydrogen atom, a hydroxyl group, a carboxyl group, an aldehyde group, a halogen atom, a group having a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. In formula (A2), R 41 and R 42 may be a hydroxyl group, a carboxyl group, an aldehyde group, a group having a halogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R 41 and R 42 may not be present. In formula (A2), a plurality of R 41 may be present, and a plurality of R 42 may be present.]
The metal component includes at least one selected from the group consisting of Li, Na, Mg, Ca, Sr, Ba, Ge, Sn, Pb, Al, Ga, In, Tl, Zn, Cd, Cu, Ag, Au, Ni, Pd, Pt, Co, Rh, Ir, Fe, Mn, Cr, Mo, W, V, Nb, Ta, Ti, and Zr;
The light absorbing composition according to any one of claims 1 to 9.
an organic solvent, a UV-absorbing compound having a hydroxyl group and a carbonyl group in the molecule,
The method includes adding and mixing a compound containing a metal component, polyvinyl butyral, and an isocyanate.
A method for producing the light absorbing composition according to any one of claims 1 to 10.
an ultraviolet absorbing compound having a hydroxy group and a carbonyl group in the molecule;
Metal components,
A resin having a urethane bond,
At least a portion of the metal component is bonded to an organic oxy group.
Light absorbing film.
the ratio of the mass of the ultraviolet absorbing compound to the mass of the metal component is 5 to 300;
The light absorbing film according to claim 12.
the urethane bond is formed between a first moiety derived from polyvinyl butyral and a second moiety derived from an isocyanate;
The ratio of the mass of the isocyanate and the second portion to the mass of the polyvinyl butyral and the first portion is 0.05 to 3.0;
The light absorbing film according to claim 12 or 13.
the urethane bond is formed between a first moiety derived from polyvinyl butyral and a second moiety derived from an isocyanate;
the ratio of the mass of the isocyanate and the second portion to the mass of the ultraviolet absorbing compound is 0.1 to 3.0;
The light absorbing film according to any one of claims 12 to 14.
the hydroxy group and the carbonyl group are separated by 1 to 3 atoms;
The light absorbing film according to any one of claims 12 to 15.
In the transmission spectrum at an incident angle of 0 degrees, the transmittance T400 at a wavelength of 400 nm is 5% or less.
The light absorbing film according to any one of claims 12 to 16.
The ultraviolet absorbing compound includes a benzophenone-based compound represented by the following formula (A1):
The light absorbing film according to any one of claims 12 to 17.

[In formula (A1), at least one of R 11 , R 12 , R 21 , and R 22 is a hydroxy group. In formula (A1), when R 11 , R 12 , R 21 , or R 22 is a functional group other than a hydroxy group, a plurality of R 11 , a plurality of R 12 , a plurality of R 21 , or a plurality of R 22 may be present, and at least one of R 11 , R 12 , R 21 , and R 22 may not be present.]
The ultraviolet absorbing compound includes a benzophenone-based compound represented by the following formula (A2):
The light absorbing film according to any one of claims 12 to 18.

[In formula (A2), R 31 is a hydrogen atom, a hydroxyl group, a carboxyl group, an aldehyde group, a halogen atom, a group having a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. In formula (A2), R 41 and R 42 may be a hydroxyl group, a carboxyl group, an aldehyde group, a group having a halogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R 41 and R 42 may not be present. In formula (A2), a plurality of R 41 may be present, and a plurality of R 42 may be present.]
A transmission spectrum obtained by irradiating light having a wavelength in the range of 300 nm to 1200 nm at an incident angle of 0° onto the light absorbing film satisfies the following requirements (ia), (ii-a), (iii-a), (iv-a), (va), and (vi-a):
The light absorbing film according to any one of claims 12 to 19.
(ia) The maximum transmittance in the wavelength range of 300 nm to 380 nm is 3% or less.
(ii-a) The transmittance at a wavelength of 400 nm is 5% or less.
(iii-a) The transmittance at a wavelength of 410 nm is 10% or less.
(iv-a) Within the wavelength range of 350 nm to 500 nm, the wavelength λ UV at which the transmittance is 50% is within the range of 405 nm to 490 nm.
(va) The minimum transmittance in the wavelength range of 480 to 600 nm is 85% or more.
(vi-a) The ratio of the transmittance at a wavelength of (λ UV +10) nm to the transmittance at a wavelength of (λ UV -10) nm is 1.8 or more.
An optical filter comprising a light absorbing film according to any one of claims 12 to 20.
A method for producing an optical filter including the light-absorbing film according to any one of claims 12 to 20, comprising the steps of:
The manufacturing method of the optical filter includes the steps of either (i) or (ii) below:
(i) forming the light absorbing film on an imaging element or an optical component;
(ii) forming the light absorbing film on a substrate and peeling the light absorbing film from the substrate;