JP6543746B1 - Optical filter manufacturing method - Google Patents

Abstract

The present invention provides an optical filter having characteristics advantageous for bringing the spectral sensitivity of an imaging device close to human visual sensitivity.
An optical filter (1a) includes a light absorption layer (10). The light absorbing layer 10 is formed of a cured product of a light absorbing composition in which a light absorbing agent formed by a phosphonic acid represented by a specific formula and a copper ion is dispersed. The optical filter 1a has (I) an average spectral transmittance of 80% or more at a wavelength of 450 nm to 600 nm, (II) a spectral transmittance of 1% or less at a wavelength of 750 nm to 900 nm, and (III) a wavelength of 350 nm to It has an average spectral transmittance of 4% or less in the range of 370 nm. The infrared side cutoff wavelength with respect to the light which injects with the incident angle of (IV) 0 degree is 620 nm-680 nm, and the ultraviolet side cutoff wavelength with respect to the light which injects with the incident angle of (V) 0 degree is 380 nm-420 nm.
[Selected figure] Figure 1

Description

  The present invention relates to an optical filter and a method of manufacturing the optical filter.

  In an imaging device using an imaging device such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), various optical filters are disposed in front of the imaging device to obtain an image having good color reproducibility. There is. In general, the imaging device has spectral sensitivity in a wide wavelength range from the ultraviolet region to the infrared region. On the other hand, human visual sensitivity exists only in the visible light region. For this reason, there is known a technique in which an optical filter for shielding infrared light is disposed in front of the image pickup device in order to make the spectral sensitivity of the image pickup device in the image pickup apparatus approach human visual sensitivity.

  For example, Patent Document 1 describes a near infrared cut filter having a norbornene resin substrate and a near infrared reflection film. The near infrared reflection film is a dielectric multilayer film. The substrate made of norbornene resin contains a near infrared absorber.

  Patent Document 2 describes a near-infrared cut filter including a laminate having a resin layer on at least one surface of a glass substrate and satisfying a predetermined condition regarding the transmittance. The resin layer contains a near infrared absorber. The near infrared cut filter preferably has a dielectric multilayer film on at least one side of the laminate.

Patent Document 3 describes a near-infrared cut filter formed of a near-infrared absorber and a resin. The near infrared absorber is obtained from a predetermined phosphonic acid compound, a predetermined phosphoric acid ester compound, and a copper salt. Certain phosphonic acid compounds have the monovalent group R ¹ represented by —CH ₂ CH ₂ —R ¹¹ bonded to the phosphorus atom P. R ¹¹ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a fluorinated alkyl group having 1 to 20 carbon atoms.

JP 2005-338395 A JP 2012-103340 A JP, 2011-203467, A

According to the techniques described in Patent Documents 1 and 2, in order for the near infrared cut filter to have the desired characteristics, it is necessary to have a dielectric multilayer film that reflects or absorbs near infrared light. In any of the near infrared cut filters described in the examples of Patent Document 2, a dielectric multilayer film in which a silica (SiO ₂ ) layer and a titania (TiO ₂ ) layer are alternately stacked is formed. For this reason, according to the techniques described in Patent Documents 1 and 2, an apparatus such as a vacuum deposition apparatus is required to manufacture the near-infrared cut filter, and the manufacturing process is likely to be complicated.

  The dielectric multilayer film has the property of changing the transmittance spectrum of the optical filter with respect to light incident at different incident angles, and in particular, shifts the transmittance spectrum of the optical filter to the short wavelength side as the incident angle increases. For this reason, when the near-infrared cut filter described in Patent Document 1 is used together with the imaging element of the imaging device, the image obtained by the imaging device has a central portion of the image because the angles of light rays incident on the optical filter are different. And the periphery of the image may have different colors. In the present specification, the “transmittance spectrum” refers to the transmittance (unit:%) of light incident on an optical filter or a part of a substrate and a functional film (functional layer) constituting the optical filter or a functional layer thereof. It means what was put in order of the wavelength.

  Although the near infrared cut filter described in Patent Document 2 has a dielectric multilayer film, the resin layer contains a near infrared absorber. Thereby, the incident angle dependency of the transmittance spectrum is reduced. However, according to Patent Document 2, it is unclear how the dielectric multilayer film and the resin layer affect the transmittance spectrum of the near infrared cut filter, and the incident angle dependency of the absorption wavelength There is also room for improvement.

  The near-infrared cut filter described in Patent Document 3 does not require a dielectric multilayer film, and it is considered that the shift of the transmittance spectrum to the short wavelength side with the increase of the incident angle of light hardly occurs. This infrared cut filter is advantageous in terms of absorbing and cutting infrared rays in a relatively wide wavelength range. However, since the range of the wavelength corresponding to the transmission region of this infrared cut filter is wide, this infrared cut filter transmits infrared light of a predetermined wavelength or ultraviolet light of a predetermined wavelength, and the optical characteristics exhibited by the infrared cut filter There is a possibility that it may be misaligned with human visual sensitivity. The transmission region means a range of wavelengths corresponding to the transmittance of 70% or more in the transmittance spectrum.

  In view of such circumstances, the present invention has an advantageous characteristic for bringing the spectral sensitivity of an image pickup device close to the human visual sensitivity, and an optical having a desired characteristic without requiring a complicated process with a simple configuration. Provide a filter. In addition, a method of manufacturing such an optical filter is provided.

［式中、Ｒ₁₁は、フェニル基又はフェニル基における少なくとも１つの水素原子がハロゲン原子に置換されているハロゲン化フェニル基である。］ The present invention
A light absorber formed of a phosphonic acid and a copper ion represented by the following formula (a), a phosphate ester for dispersing the light absorber, and a curable resin, the light absorber being dispersed And a light absorbing layer formed by curing the light absorbing composition.
(I) having an average spectral transmittance of 80% or more at a wavelength of 450 nm to 600 nm,
(II) having a spectral transmittance of 1% or less at a wavelength of 750 nm to 900 nm,
(III) having an average spectral transmittance of 4% or less in the wavelength range of 350 nm to 370 nm,
(IV) A wavelength at which the spectral transmittance of the optical filter is 50% at a wavelength of 600 nm to 800 nm and having a spectral transmittance of 50% at a wavelength of 600 nm to 800 nm is defined as the infrared side cutoff wavelength The infrared side cutoff wavelength for light incident on the optical filter at an incident angle of 0 ° is 620 nm to 680 nm,
(V) A wavelength at which the spectral transmittance of the optical filter is 50% at a wavelength of 350 nm to 450 nm is defined as the ultraviolet side cutoff wavelength. The UV cut-off wavelength for light incident on the optical filter at an incident angle of 0 ° is 380 nm to 420 nm.
Provide an optical filter.

[Wherein, R ₁₁ is a phenyl group or a halogenated phenyl group in which at least one hydrogen atom in the phenyl group is substituted by a halogen atom]. ]

［式中、Ｒ₁₁は、フェニル基又はフェニル基における少なくとも１つの水素原子がハロゲン原子に置換されているハロゲン化フェニル基である。］ Also, the present invention is
Providing a substrate having a surface containing an organic fluorine compound and having a surface roughness Ra of 50 nm or less as defined in JIS B 0601: 1994;
A light absorber formed of a phosphonic acid and a copper ion represented by the following formula (a), a phosphate ester for dispersing the light absorber, and a curable resin, the light absorber being dispersed Applying the light absorbing composition on the surface of the substrate to form a coating, and curing the coating to form a light absorbing layer;
Peeling off the light absorbing layer from the substrate;
Provided is a method of manufacturing an optical filter.

[Wherein, R ₁₁ is a phenyl group or a halogenated phenyl group in which at least one hydrogen atom in the phenyl group is substituted by a halogen atom]. ]

  The above-described optical filter has advantageous characteristics for bringing the spectral sensitivity of the imaging device close to human visual sensitivity, and has desired characteristics without requiring a complicated process with a simple configuration. Further, according to the above manufacturing method, an optical filter with a simpler configuration can be obtained.

FIG. 1 is a cross-sectional view showing an optical filter according to an example of the present invention. FIG. 2 is a cross-sectional view showing an optical filter according to another example of the present invention. FIG. 3 is a cross-sectional view showing an optical filter according to another example of the present invention. FIG. 4 is a cross-sectional view showing an optical filter according to another example of the present invention. FIG. 5 is a cross-sectional view showing an optical filter according to another example of the present invention. FIG. 6 is a cross-sectional view showing an imaging optical system provided with an optical filter according to an example of the present invention. FIG. 7A is a transmittance spectrum of the optical filter according to Example 1. FIG. 7B is another transmittance spectrum of the optical filter according to the first embodiment. FIG. 8 is a transmittance spectrum of the optical filter according to the nineteenth embodiment. FIG. 9 is a transmittance spectrum of the optical filter according to the twentieth embodiment. FIG. 10 is a transmittance spectrum of the optical filter according to Example 21. FIG. 11 is a transmittance spectrum of the optical filter according to Example 22. FIG. 12 is a transmittance spectrum of the optical filter according to Example 23. FIG. 13 is a transmittance spectrum of the optical filter according to Example 24. FIG. 14 is a transmittance spectrum of the optical filter according to Example 25. FIG. 15 is a transmittance spectrum of the optical filter according to Comparative Example 4. FIG. 16 is a transmittance spectrum of the optical filter according to Comparative Example 5. FIG. 17 is a transmittance spectrum of the optical filter according to Comparative Example 6. FIG. 18 is a transmittance spectrum of the optical filter according to Comparative Example 7.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description relates to an example of the present invention, and the present invention is not limited thereto.

［式中、Ｒ₁₁は、フェニル基又はフェニル基における少なくとも１つの水素原子がハロゲン原子に置換されているハロゲン化フェニル基である。］ As shown in FIGS. 1 to 5, optical filters 1 a to 1 e which are examples of the optical filter according to the present invention include a light absorbing layer 10. The light absorption layer 10 may be in a state of being disposed on a predetermined substrate, or may be in a state of being peeled off from the substrate after being formed on the predetermined substrate. The light absorbing layer 10 contains a light absorbing agent formed of a phosphonic acid represented by the following formula (a) and a copper ion, a phosphate ester for dispersing the light absorbing agent, and a curable resin. It is formed of a cured product of the light absorbing composition in which the absorber is dispersed. The optical filters 1a to 1e satisfy the following (I) to (V).
(I) The optical filters 1a to 1e have an average spectral transmittance of 80% or more at wavelengths of 450 nm to 600 nm.
(II) The optical filters 1a to 1e have a spectral transmittance of 1% or less at wavelengths of 750 nm to 900 nm.
(III) The optical filters 1a to 1e have an average spectral transmittance of 4% or less in the wavelength range of 350 nm to 370 nm.
(IV) The optical filters 1a to 1e have a spectral transmittance that decreases with an increase in wavelength at wavelengths of 600 nm to 800 nm. When the wavelength at which the spectral transmittance of the optical filters 1a to 1e becomes 50% at a wavelength of 600 nm to 800 nm is defined as the infrared side cutoff wavelength, the infrared side to light incident on the optical filters 1a to 1e at an incident angle of 0 ° The cutoff wavelength is 620 nm to 680 nm.
(V) The optical filters 1a to 1e have spectral transmittances at wavelengths of 350 nm to 450 nm that increase as the wavelength increases. When the wavelength at which the spectral transmittance of the optical filters 1a to 1e becomes 50% at a wavelength of 350 nm to 450 nm is defined as the ultraviolet side cutoff wavelength, the ultraviolet side to light incident on the optical filters 1a to 1e at an incident angle of 0 ° The cutoff wavelength is 380 nm to 420 nm.

[Wherein, R ₁₁ is a phenyl group or a halogenated phenyl group in which at least one hydrogen atom in the phenyl group is substituted by a halogen atom]. ]

  When the optical filters 1a to 1d are disposed on the front surface of the imaging device by satisfying the condition (I) of the optical filters 1a to 1e, visible light received by the imaging device in the wavelength range of 450 nm to 600 nm There is a lot of light. When the optical filters 1a to 1e satisfy the above condition (II), the optical filters 1a to 1e can advantageously shield infrared light of 750 nm to 900 nm. In addition, when the optical filters 1a to 1e satisfy the above condition (III), the optical filters 1a to 1e can advantageously shield ultraviolet light of 370 nm or less. As a result, when the optical filters 1a to 1e are disposed in front of the imaging device, the spectral sensitivity of the imaging device can be advantageously brought close to human visibility. Furthermore, when the optical filters 1a to 1e satisfy the above conditions (IV) and (V), light in the infrared region and the ultraviolet region is advantageously shielded. As a result, when the optical filters 1a to 1e are disposed in front of the imaging device, the spectral sensitivity of the imaging device can be advantageously brought close to human visibility.

  Regarding the conditions of the above (I), the optical filters 1a to 1e desirably have an average spectral transmittance of 85% or more at a wavelength of 450 nm to 600 nm. Thus, when the optical filters 1a to 1e are disposed in front of the imaging device, the amount of visible light received by the imaging device is larger in the wavelength range of 450 nm to 600 nm.

  With regard to the condition (II), the optical filters 1a to 1e desirably have a spectral transmittance of 0.5% or less at wavelengths of 750 nm to 900 nm. Regarding the condition of the above (III), the optical filters 1a to 1e desirably have an average spectral transmittance of 1% or less in the wavelength range of 350 nm to 370 nm. As a result, when the optical filters 1a to 1e are disposed in front of the imaging device, the spectral sensitivity of the imaging device can be made closer to the human visual sensitivity.

  With regard to the condition (IV) above, desirably, the infrared cutoff wavelength for light incident on the optical filters 1a to 1e at an incident angle of 0 ° is 630 nm or more, or 660 nm or less. With regard to the condition (V), desirably, the ultraviolet side cutoff wavelength for light incident on the optical filters 1a to 1e at an incident angle of 0 ° is 390 nm or more, or 410 nm or less. As a result, when the optical filters 1a to 1e are disposed in front of the imaging device, the spectral sensitivity of the imaging device can be made closer to the human visual sensitivity.

The optical filters 1a to 1e desirably satisfy the following (VI) and (VII).
(VI) The difference between the infrared cutoff wavelength for light incident on the optical filters 1a to 1e at an incident angle of 0 ° and the infrared cutoff wavelength for light incident on the optical filters 1a to 1e at an incident angle of 40 ° It is 20 nm or less, preferably 10 nm or less.
(VII) The difference between the ultraviolet side cutoff wavelength for light incident on the optical filters 1a to 1e at an incidence angle of 0 ° and the ultraviolet side cutoff wavelength for light incident on the optical filters 1a to 1e at an incidence angle of 40 ° It is 20 nm or less, preferably 10 nm or less.

  When the optical filters 1a to 1e are disposed on the front of the imaging device by satisfying the conditions (VI) and (VII) described above, the spectral sensitivity of the imaging device is incident on the imaging device It is difficult to change depending on the incident angle of light.

  As shown in FIGS. 1 to 4, the optical filters 1 a to 1 d further include, for example, a transparent dielectric substrate 20.

  The transparent dielectric substrate 20 in the optical filters 1a to 1d is, for example, a dielectric substrate having an average spectral transmittance of 90% or more at 450 nm to 600 nm. The transparent dielectric substrate 20 may be a substrate made of glass containing CuO (copper oxide) having an absorbing power in the infrared region. Also in this case, the optical filters 1a to 1d which satisfy the above conditions (I) to (V) can be obtained. Of course, the transparent dielectric substrate 20 may have, for example, an average spectral transmittance of 90% or more at a wavelength of 350 nm to 900 nm. The material of the transparent dielectric substrate 20 is not limited to a specific material, and is, for example, a predetermined glass or resin. When the material of the transparent dielectric substrate 20 is glass, the transparent dielectric substrate 20 is, for example, transparent glass or infrared cut glass made of silicate glass such as soda lime glass and borosilicate glass. The infrared cut glass is, for example, phosphate glass or fluorophosphate glass containing CuO. When the transparent dielectric substrate 20 is an infrared cut glass, the infrared absorption ability of the light absorption layer 10 can be reduced by the infrared absorption ability of the infrared cut glass. As a result, the thickness of the light absorbing layer 10 can be reduced, or the concentration of the light absorbing agent contained in the light absorbing layer 10 can be reduced. The infrared side cut-off wavelength in the transmittance spectrum of the infrared cut glass tends to exist relatively on the long wavelength side. For this reason, the infrared side cutoff wavelength of the optical filters 1a to 1d is on the short wavelength side by curing the above light absorbing composition and forming the light absorbing layer 10 on the transparent dielectric substrate 20 which is infrared cut glass. It is easy to match the spectral sensitivity of the imaging device to the human visual sensitivity.

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

  As shown in FIG. 5, the optical filter 1e does not have a substrate such as a transparent dielectric substrate. In other words, the optical filter 1 e is a substrateless optical filter. In this case, the thickness of the optical filter 1e tends to be small.

  As described in formula (a), the phosphonic acid forming the light absorbing agent comprises a phenyl group or a halogenated phenyl group in which at least one hydrogen atom in the phenyl group is substituted with a halogen atom. Since the phenyl group and the halogenated phenyl group have high lipophilicity, they have high compatibility with an organic solvent such as toluene and the light absorber is less likely to aggregate. The light absorbing layer 10 of the optical filters 1a to 1e tends to have a flexible structure due to the phenyl group or the halogenated phenyl group which the phosphonic acid forming the light absorbing agent has. As a result, the light absorption layer 10 has good crack resistance.

  The ratio of the content of phosphonic acid to the content of phosphoric acid ester in the light absorbing composition containing the light absorbing agent formed by the phosphonic acid and the copper ion represented by the formula (a) is, for example, on a mass basis The ratio of the phosphonic acid content to the copper ion content is, for example, 0.45 to 0.80 on the basis of substance mass (mole). Thereby, in the light absorbing composition, the light absorbing agent is easily dispersed well.

  For example, in the light absorption layer 10 of the optical filters 1a to 1e, the ratio of the content of phosphonic acid to the content of phosphoric acid ester is 0.10 to 0.48 on a mass basis, and the content of copper ions The ratio of the content of phosphonic acid to is from 0.45 to 0.80 based on the mass of substance.

［式中、Ｒ₁₂は、６個以下の炭素原子を有するアルキル基である。］ The light absorbing composition may further optionally contain an auxiliary light absorbing agent formed of a phosphonic acid represented by the following formula (b) and a copper ion.

[Wherein, R ₁₂ is an alkyl group having 6 or less carbon atoms. ]

  For example, the light absorbing layer 10 of the optical filters 1a to 1e further contains an auxiliary light absorbing agent formed of the phosphonic acid represented by the above formula (b) and a copper ion.

When the light absorbing composition contains the auxiliary light absorbing agent, for example, the transmittance of light with a wavelength of 850 nm or more or a wavelength of 900 nm or more of the optical filters 1a to 1e can be advantageously reduced. The alkyl group which is R ₁₂ may be linear or branched. The ratio of the content of the phosphonic acid represented by the formula (b) to the content of the phosphonic acid represented by the formula (a) is, for example, 0.05 to 0.50 on a mass basis, preferably 0. It is 07-0.30.

The phosphoric acid ester contained in the light absorbing composition is not particularly limited as long as the light absorbing agent can be appropriately dispersed, but, for example, the phosphoric acid diester represented by the following formula (c1) and the following formula (c2) And / or at least one of the following phosphoric monoesters. Thereby, the light absorbing composition can be more reliably dispersed in the light absorbing composition without aggregation. In the following formula (c1) and the following formula (c2), R ₂₁ , R ₂₂ and R ₃ are each a monovalent functional group represented by — (CH ₂ CH ₂ O) _n R ₄ And n are integers of 1 to 25 and R ₄ represents an alkyl group having 6 to 25 carbon atoms. R ₂₁ , R ₂₂ and R ₃ are functional groups of the same or different type from one another.

  The light absorbing agent is formed, for example, by coordination of a phosphonic acid represented by the formula (a) to a copper ion. Also, for example, fine particles containing at least a light absorbing agent are formed in the light absorbing composition. In this case, the fine particles are dispersed in the light absorbing composition without aggregation due to the action of the phosphate ester. The average particle size of the fine particles is, for example, 5 nm to 200 nm. If the average particle size of the fine particles is 5 nm or more, no special process is required to make the fine particles fine, and the structure of the fine particles containing at least the light absorbing agent is less likely to be broken. In addition, fine particles are well dispersed in the light absorbing composition. In addition, when the average particle diameter of the fine particles is 200 nm or less, the influence of Mie scattering can be reduced, the transmittance of visible light can be improved in the optical filter, and the contrast and haze of the image captured by the imaging device It is possible to suppress the deterioration of characteristics. The average particle size of the particles is desirably 100 nm or less. In this case, since the influence of Rayleigh scattering is reduced, the transparency to visible light is further enhanced in the light absorbing layer formed using the light absorbing composition. The average particle size of the fine particles is more preferably 75 nm or less. In this case, the transparency of the light absorbing layer to visible light is particularly high. In addition, the average particle diameter of microparticles | fine-particles can be measured by a dynamic light scattering method.

  When the light absorbing composition contains an auxiliary light absorbing agent, the auxiliary light absorbing agent is formed, for example, by coordination of a phosphonic acid represented by the formula (b) to a copper ion. Also, for example, fine particles containing at least an auxiliary light absorbing agent are formed in the light absorbing composition. The average particle size of the particles containing the auxiliary light absorbing agent is, for example, the same as the average particle diameter of the particles containing the light absorbing agent.

The source of copper ions in the light absorbing composition is, for example, a copper salt. The copper salt is, for example, copper acetate or a hydrate of copper acetate. Copper salts can include copper chloride, copper formate, copper stearate, copper benzoate, copper pyrophosphate, copper naphthenate, and anhydrides or hydrates of copper citrate. For example, copper acetate monohydrate is represented as Cu (CH ₃ COO) ₂ .H ₂ O, and one mole of copper acetate monohydrate provides one mole of copper ions.

  The curable resin of the light absorbing composition can be dispersed, for example, a light absorbing agent, can be thermally cured or UV cured, and is a resin whose cured product is transparent to light having a wavelength of 350 nm to 900 nm. It is. The content of the phosphonic acid represented by the formula (a) is, for example, 3 to 180 parts by mass with respect to 100 parts by mass of the curable resin.

The curable resin of the light absorbing composition is desirably a polysiloxane (silicone resin). Thereby, the heat resistance of the light absorption layer formed of the light absorption composition can be improved. The polysiloxane desirably contains an aryl group such as a phenyl group. When the resin layer contained in the optical filter is hard (is rigid) and the thickness of the resin layer is increased, cracks easily occur due to curing shrinkage during the manufacturing process of the optical filter. If the curable resin of the light absorbing composition is a polysiloxane containing an aryl group, the light absorbing layer formed of the light absorbing composition tends to have good crack resistance. Moreover, the polysiloxane containing an aryl group has high compatibility with a phosphonic acid having a phenyl group or a halogenated phenyl group, and the light absorber is less likely to aggregate. Furthermore, when the curable resin of the light absorbing composition is a polysiloxane containing an aryl group, the phosphoric acid ester contained in the light absorbing composition is represented by the formula (c1) or the formula (c2) It is desirable to have a flexible linear organic functional group such as an oxyalkyl group as an ester. This is because the light absorbing agent is an interaction based on the combination of a phosphonic acid having a phenyl group or a halogenated phenyl group, a polysiloxane containing an aryl group, and a phosphoric acid ester having a linear organic functional group such as an oxyalkyl group. Is highly compatible with the curable resin and the phosphoric acid ester, and by curing the light absorbing composition, it is possible to form a light absorbing layer having both good rigidity and good flexibility. Specific examples of the polysiloxane that can be used as the curable resin include KR-255, KR-300, KR-2621-1, KR-211, KR-311, KR-216, KR-212, and KR-251. It can be mentioned. All of these are silicone resins manufactured by Shin-Etsu Chemical Co., Ltd. As curable resin, resin, such as an acrylic resin, an epoxy resin, and vinyl acetal resin, can also be used. These resins may contain any of monofunctional or polyfunctional monomers, oligomers, and polymers as constituent units. In addition, polysiloxane (silicone resin) is expected to be able to exert high adhesion to a glass substrate containing SiO ₂ or a dielectric film whose layer in contact with polysiloxane is a SiO ₂ layer.

  An example of the preparation method of the light absorptive composition concerning this invention is demonstrated. First, a copper salt such as copper acetate monohydrate is added to a predetermined solvent such as tetrahydrofuran (THF) and stirred to obtain a copper salt solution. Next, a phosphoric acid diester represented by the formula (c1) and a phosphoric acid ester compound such as a phosphoric acid monoester represented by the formula (c2) are added to the solution of the copper salt and stirred to prepare a solution A. Do. Moreover, the phosphonic acid represented by Formula (a) is added to predetermined | prescribed solvent, such as THF, and it stirs, and prepares B liquid. In the preparation of the solution B, if necessary, the phosphonic acid represented by the formula (b) may be added to a predetermined solvent. Next, while stirring solution A, solution B is added to solution A and stirred for a predetermined time. Next, a predetermined solvent such as toluene is added to the solution and stirred to obtain a solution C. Next, the solvent removal treatment is performed for a predetermined time while heating the solution C. As a result, a solvent such as THF and a component generated by dissociation of a copper salt such as acetic acid (boiling point: about 118 ° C.) are removed, and a light absorber is formed by the phosphonic acid represented by formula (a) and a copper ion. Be done. The temperature for heating solution C is determined based on the boiling point of the component to be removed which has been dissociated from the copper salt. In the desolvation treatment, a solvent such as toluene (boiling point: about 110 ° C.) used to obtain the liquid C also evaporates. Since it is desirable that this solvent remains in the light absorbing composition to a certain extent, it is preferable from this viewpoint that the amount of the solvent added and the time for the desolvation treatment be determined. In order to obtain liquid C, o-xylene (boiling point: about 144 ° C.) can be used instead of toluene. In this case, since the boiling point of o-xylene is higher than the boiling point of toluene, the amount of addition can be reduced to about one fourth of the amount of addition of toluene.

  After the desolvation treatment of the liquid C, a curable resin such as polysiloxane (silicone resin) is added and stirred for a predetermined time. For example, in this way, the light absorbing composition according to the present invention can be prepared. It is desirable that the solvent used for preparation of the light absorbing composition have a predetermined polarity from the viewpoint of appropriately forming a light absorbing agent with the phosphonic acid represented by the formula (a) and a copper ion. The reason is that the polarity of the solvent affects the dispersion of the fine particles containing at least the light absorbing agent in the light absorbing composition. For example, a solvent having an appropriate polarity is selected according to the type of phosphoric acid ester used for preparation of solution A.

  The light absorption layer 10 in the optical filters 1a to 1e has a thickness of, for example, 30 μm to 800 μm. Thus, the optical filters 1a to 1e advantageously satisfy the above conditions (I) to (V). In addition, as shown in FIG. 3, when the light absorption layer 10 is divided into two or more layers, the sum of the thickness of each layer is defined as the thickness of the light absorption layer 10. As described above, when a polysiloxane containing an aryl group is used as a curable resin of a light absorbing composition, a light absorbing layer having both good rigidity and good flexibility can be formed by curing the light absorbing composition. . For this reason, when using polysiloxane containing an aryl group as curable resin of a light absorption composition, it is easy to make thickness of the light absorption layer 10 comparatively large, and many light absorption agents are included in a light absorption layer. it can. When using a polysiloxane containing an aryl group as the curable resin of the light absorbing composition, the thickness of the light absorbing layer 10 in the optical filters 1a to 1e is desirably 80 μm to 500 μm, and more desirably 100 μm to 400 μm. is there.

  An example of the manufacturing method of the optical filter 1a which concerns on an example of this invention is demonstrated. First, a liquid light absorbing composition is applied to one main surface of the transparent dielectric substrate 20 by spin coating or application by a dispenser to form a coating film. Next, this coating film is subjected to a predetermined heat treatment to cure the coating film. Thus, the optical filter 1a can be manufactured. From the viewpoint of enhancing the optical characteristics of the optical filter 1a while firmly forming the light absorbing layer 10, the maximum value of the atmosphere temperature of the coating film in the heat treatment is, for example, 140 ° C. or higher, preferably 160 ° C. or higher. Moreover, the maximum value of the atmospheric temperature of the coating film in heat processing is 170 degrees C or less, for example.

As shown in FIG. 2, an optical filter 1 b according to another example of the present invention includes an infrared reflective film 30. The infrared reflective film 30 is a film formed by alternately laminating a plurality of materials having different refractive indexes. The material forming the infrared reflective film 30 is, for example, an inorganic material such as SiO ₂ , TiO ₂ and MgF ₂ or an organic material such as a fluorine resin. The laminate in which the infrared reflective film 30 is formed on a transparent dielectric substrate transmits, for example, light with a wavelength of 350 nm to 800 nm and reflects light with a wavelength of 850 nm to 1200 nm. The laminated body provided with the infrared reflection film 30 has a spectral transmittance of, for example, 85% or more, preferably 90% or more at a wavelength of 350 nm to 800 nm, and preferably, for example, 1% or less at a wavelength of 850 nm to 1200 nm. Have a spectral transmittance of 0.5% or less. Thereby, the optical filter 1b can block the light of the wavelength range of 850 nm to 1200 nm or the light of the wavelength range of 900 nm to 1200 nm more effectively. In addition, when the spectral transmittance of the laminate provided with the infrared reflective film 30 has the above-mentioned characteristics, the shift of the transmittance spectrum of the laminate provided with the infrared reflective film 30 due to the change of the incident angle of light causes the optical filter 1b Influence on the transmittance spectrum of This is because the light absorbing agent formed by the phosphonic acid and the copper ion represented by the formula (a) has a light absorbing ability in a region where a wavelength shift appears in the transmission spectrum of the infrared reflecting film with the fluctuation of the incident angle of light. In order to have

  The method for forming the infrared reflective film 30 of the optical filter 1b is not particularly limited, and vacuum deposition, sputtering, chemical vapor deposition (CVD), spin coating or spray depending on the type of the material forming the infrared reflective film 30. Any of the sol-gel methods utilizing a coating can be used.

  As shown in FIG. 3, in the optical filter 1 c according to another example of the present invention, the light absorption layer 10 is formed on both main surfaces of the transparent dielectric substrate 20. Thereby, the thickness of the light absorption layer necessary for the optical filter 1 c to obtain desired optical characteristics can be secured not by one light absorption layer 10 but by two light absorption layers 10. The thickness of the light absorption layer 10 on both main surfaces of the transparent dielectric substrate 20 may be the same or different. That is, the light absorbing layer 10 is formed on both main surfaces of the transparent dielectric substrate 20 so that the thickness of the light absorbing layer necessary for the optical filter 1c to obtain the desired optical characteristics may be evenly or unevenly distributed. Is formed. Thereby, the thickness of each light absorption layer 10 formed on both main surfaces of the transparent dielectric substrate 20 is relatively small. For this reason, the dispersion | variation in the thickness of the light absorption layer which arises when the thickness of a light absorption layer is large can be suppressed. Moreover, the time which apply | coats a liquid light absorptive composition can be shortened, and the time for hardening the coating film of a light absorptive composition can be shortened. When the transparent dielectric substrate 20 is very thin, forming the light absorbing layer 10 only on one of the main surfaces of the transparent dielectric substrate 20 may cause shrinkage that occurs when the light absorbing layer 10 is formed from the light absorbing composition. The stresses involved can cause the optical filter to warp. However, since the light absorption layer 10 is formed on both main surfaces of the transparent dielectric substrate 20, warpage is suppressed in the optical filter 1c even when the transparent dielectric substrate 20 is very thin.

  As shown in FIG. 4, an optical filter 1 d according to another example of the present invention further includes an auxiliary light absorbing layer 15 formed in parallel with one main surface of the transparent dielectric substrate 20. The auxiliary light absorbing layer 15 is, for example, an auxiliary light absorbing agent formed of a phosphonic acid represented by the above formula (b) and a copper ion, a phosphate ester for dispersing the auxiliary light absorbing agent, and a curing property. It is formed of a cured product of an auxiliary light absorbing composition containing a resin. By providing the auxiliary light absorption layer 15, the optical filter 1d can advantageously reduce the transmittance of light with a wavelength of 850 nm or more or a wavelength of 900 nm or more.

  As shown in FIG. 4, for example, the light absorption layer 10 is formed on one main surface of the transparent dielectric substrate 20, and the auxiliary light absorption layer 15 is formed on the other main surface of the transparent dielectric substrate 20. . In this case, the stress applied to the transparent dielectric substrate 20 with the formation of the light absorption layer 10 and the stress applied to the transparent dielectric substrate 20 with the formation of the auxiliary light absorption layer 15 are balanced, and a warp occurs in the optical filter 1 d. Can be prevented.

  As the phosphate ester and the curable resin in the auxiliary light absorbing composition, for example, the same material as the phosphate ester and the curable resin in the light absorbing composition can be used.

  A liquid auxiliary light absorbing composition is applied to one main surface of the transparent dielectric substrate 20 by spin coating or application by a dispenser to form a coating film. Next, this coating film is subjected to a predetermined heat treatment to cure the coating film. Thus, the optical filter 1d can be manufactured. From the viewpoint of enhancing the optical characteristics of the optical filter 1d while firmly forming the auxiliary light absorbing layer 15, the maximum value of the atmosphere temperature of the coating film in the heat treatment is, for example, 140 ° C. or higher, preferably 160 ° C. or higher. Moreover, the maximum value of the atmospheric temperature of the coating film in heat processing is 170 degrees C or less, for example. The heat treatment for forming the light absorption layer 10 and the auxiliary light absorption layer 15 may be performed simultaneously.

  As shown in FIG. 5, an optical filter 1e according to another example of the present invention is substrateless. An example of a method of manufacturing the optical filter 1 e will be described. The liquid light absorbing composition is applied to one main surface of a predetermined substrate by spin coating or application by a dispenser to form a coating. Next, the coating film is subjected to a predetermined heat treatment to cure the coating film to obtain a light absorbing layer. Thereafter, the light absorption layer is peeled off from the substrate to produce the optical filter 1e. In this case, the surface roughness Ra defined in Japanese Industrial Standard (JIS) B 0601: 1994 on the substrate is, for example, 50 nm or less, preferably 10 nm or less, and more preferably 5 nm or less. The material and the transparency of the substrate are not particularly limited because it is intended to peel off the light absorbing layer from the substrate. As the substrate, in addition to a glass substrate, a metal substrate, a ceramic substrate, and a resin substrate can be used. Among them, the use of a glass substrate is desirable because of having a smooth surface, the ready availability of substrates of various thicknesses, and the low cost. Among the glass substrates, for example, a glass substrate with a parting film is used. Desirably, a glass substrate having a film (surface) containing an organic fluorine compound is provided. Then, the light absorbing composition is applied onto the surface of the substrate to form a coating, and the coating is cured to form a light absorbing layer. By the function of the film (surface) containing the organic fluorine compound, it can be peeled from the glass substrate without damaging the light absorption layer. It is desirable that the surface roughness of the surface of the glass substrate on which a mold release film such as a film containing such an organic fluorine compound is formed be maintained within the above range. In addition, although it does not specifically limit as a board | substrate, The board | substrates of fluororesins, such as a polytetrafluoroethylene, polychloro trifluoro ethylene, and polyvinyl fluoride, can also be used. Thus, the substrate desirably has a surface comprising an organofluorine compound.

  An ordinary glass substrate has high adhesion to the light absorbing layer, so when peeling the light absorbing layer from the substrate, the surface of the light absorbing layer is easily scratched or wrinkled, which causes the haze of the optical filter to increase. sell. Further, depending on the state of the main surface of the substrate, it may be difficult to peel off the light absorption layer itself. On the other hand, if a substrate made of a fluorine resin is used, it is possible to peel off the light absorption layer without damaging it. However, the surface of the fluorocarbon resin substrate manufactured according to the normal processing accuracy has unevenness, and the shape of the unevenness is transferred to the surface of the light absorption layer, which may be a factor to increase the haze in the optical filter. For this reason, it is desirable to use a substrate in which a film containing an organic fluorine compound is formed on a glass substrate having a smooth surface for the release of a light absorption layer. The organic fluorine compound is not limited to a specific compound as long as the desired releasability can be imparted to the substrate. Organic fluorine compounds include, for example, perfluoropolyethers. For example, a coating liquid containing OPTOOL DSX manufactured by Daikin Industries, Ltd. can be applied to one main surface of a glass substrate to produce a glass substrate with a releasing film. The application of the coating liquid can be performed by coating such as spin coating, dip coating, and spray coating.

  It is desirable that the state of the surface of the glass substrate be a smooth state without any unevenness that adversely affects the haze of the optical filter. For this reason, after a coating liquid is apply | coated to one main surface of a glass substrate, a coating film is formed, and the coating film is fully dried, then, it is a liquid containing inactive organic fluorine compounds, such as a hydrofluoroether. It is effective to immerse the glass substrate for ultrasonic treatment. This is because the excess organic fluorine compound is removed by this.

  When forming a light absorption layer on the surface containing the organic fluorine compound of the substrate, or when peeling off the formed light absorption layer from the film containing the organic fluorine compound of the substrate, a part of the film containing the organic fluorine compound Component of the light absorbing layer may penetrate into the light absorbing layer. There is also a possibility that a part of the film containing the organic fluorine compound is transferred onto the light absorption layer. In this case, an organic fluorine compound may be contained in the light absorption layer. For example, the light absorbing layer may contain 10% by mass or less of fluorine atoms. When an organic fluorine compound is present on the surface of the light absorption layer, when a film such as an antireflective film is formed on the light absorption layer, the film may be easily peeled off or the adhesion of the film may be reduced. is there. For this reason, the fluorine atom contained in the light absorbing layer is desirably 5% by mass or less, and more desirably 1% by mass or less, from the viewpoint of ease of rework. In order to remove the organic fluorine compound contained in the light absorption layer, the light absorption layer may be washed with a suitable cleaning agent such as a solvent.

  Desirably, a frame is disposed on the surface of a substrate such as a substrate having a surface comprising an organic fluorine compound, and the light absorbing composition is applied to the inside of the frame and onto the surface of the substrate. The frame is desirably formed of a material having an Asker C hardness of 10-80.

  The light absorbing layer desirably has a thickness of 30 μm or more. When the light absorbing composition is applied to a glass substrate, if the viscosity of the light absorbing composition is low, the light absorbing composition flows out of the desired range on the glass substrate and the light absorbing composition has a sufficient thickness. It is difficult to obtain a layer. Then, if the frame which functions as a dam for preventing the outflow of a light absorptive composition is used, the light absorption layer which has appropriate thickness will be easy to be obtained. Although the shape of the frame is not particularly limited, it may be, for example, a square shape in plan view, and may have a mouth shape. This frame desirably adheres to the glass substrate to such an extent that the light absorbing composition does not leak from the gap, and can be separated from the glass substrate after the formation of the light absorbing layer. The material of the frame is, for example, resin, glass or metal. Among them, the material of the frame is preferably a resin, more preferably a resin such as polyurethane and silicone. These resins are suitably soft, have adequate adhesion to the smooth surface of the glass substrate, and can arrange a resin frame on the glass substrate without any special surface treatment. The hardness of the resin of the resin frame is, for example, 10 to 80 in Asker C hardness, and preferably 10 to 65 in Asker C hardness. When the resin has such hardness, it is possible to easily attach the resin frame to the glass and to easily separate the resin frame from the glass. In addition, when the thickness of the light absorbing layer has a specific thickness of, for example, 30 μm or more, the light absorbing layer can be peeled together from the glass substrate by peeling the frame from the glass substrate, and the optical filter is easily made Can be manufactured. When the frame is made of resin, the light absorbing composition also contains the resin, so the adhesion with the resin frame tends to be high, and a certain degree of integrity occurs, and such a thing is realized It becomes possible. In addition, the hardness of the material of a frame can be evaluated based on JISK7312: 1996. Using a durometer (Asker rubber hardness meter C, manufactured by Kobunshi Keiki Co., Ltd.), press the push needle in a state where three 50 mm square (5 mm thick) test pieces are stacked, and obtain the hardness value from the pressing depth Can. Measured values are measured, for example, at 5 points at a distance of 6 mm or more, and the median value is adopted.

  In order to peel the light absorbing layer from the substrate, it is conceivable to pinch the end of the light absorbing layer with tweezers or to attach an adhesive sheet to the light absorbing layer, but this is not an efficient method. As described above, the method of peeling the light absorption layer from the substrate together with the resin frame is efficient. This method is applicable to a light absorption layer having a thickness of 30 μm or more, and more effectively applicable to a light absorption layer having a thickness of 80 μm or more.

  In the manufacture of the optical filter 1e, a predetermined heat treatment is performed to cure the coating of the light absorbing composition. The conditions of the heat treatment are, for example, the same as the conditions of the heat treatment in the production of the optical filter 1a.

The optical filter 1 e may be changed to an optical filter further including an antireflective film formed on one main surface of the light absorption layer 10 or both main surfaces of the light absorption layer 10. The antireflective film is formed to form an interface between the optical filter and the air, and is a film for reducing the reflection of light in the visible light region. The antireflective film is formed of, for example, a dielectric such as a resin, an oxide, and a fluoride. The antireflective film may be a multilayer film formed by laminating two or more types of dielectrics having different refractive indexes. In particular, the antireflective film may be a dielectric multilayer film composed of a low refractive index material such as SiO ₂ and a high refractive index material such as TiO ₂ or Ta ₂ O ₅ . In this case, Fresnel reflection at the interface between the optical filter and the air is reduced, and the amount of light in the visible light region of the optical filter can be increased. In some cases, in order to improve the adhesion of the antireflective film, a resin layer containing a silane coupling agent may be formed between the light absorbing layer and the antireflective film.

  As shown in FIG. 6, for example, the imaging optical system 100 can be provided using the optical filter 1a. The imaging optical system 100 further includes, for example, an imaging lens 3 in addition to the optical filter 1a. The imaging optical system 100 is disposed in front of the imaging element 2 in an imaging device such as a digital camera. The imaging device 2 is, for example, an imaging device such as a CCD or a CMOS. As shown in FIG. 6, light from the subject is condensed by the imaging lens 3, and after ultraviolet light and infrared light are cut by the optical filter 1 a, the light enters the imaging element 2. For this reason, the spectral sensitivity of the imaging device 2 is close to human visual sensitivity, and a good image with high color reproducibility can be obtained. The imaging optical system 100 may include any of an optical filter 1b, an optical filter 1c, an optical filter 1d, and an optical filter 1e, instead of the optical filter 1a.

  The examples illustrate the invention in more detail. The present invention is not limited to the following examples. First, an evaluation method regarding the spectral transmittance of the optical filter according to the example and the comparative example will be described.

<Transmittance spectrum measurement of optical filter>
The transmittance spectrum when light in the wavelength range of 300 nm to 1200 nm is made incident on the optical filters according to some examples and some comparative examples is a UV-visible spectrophotometer (manufactured by JASCO, product name: V It measured using -670). In this measurement, the incident angle of the incident light to the optical filters according to some examples and some comparative examples was set to 0 ° (degree). In order to exclude the influence of the transmittance | permeability spectrum by the difference in the thickness of the light absorption layer of an optical filter, the transmittance | permeability in wavelength 750nm-900 nm was normalized so that it might become a predetermined value, respectively. Specifically, the transmittance spectra measured for optical filters according to some examples and some comparative examples are multiplied by 100/92 to cancel reflection at the interface, and the transmittance at each wavelength is converted to absorbance. Then, the normalized transmittance spectrum was calculated by further multiplying 92/100 by the value adjusted and multiplied by the normalization coefficient. Here, the normalization factor was determined in accordance with each of the following two conditions (1) and (2).
Condition (1): Adjustment condition (2) in the measured transmittance spectrum such that the maximum transmittance in the wavelength range of 750 to 900 nm is 1.0% in the measured transmittance spectrum Adjusted to have a maximum transmittance of 0.5%.

  The above conditions (1) and (2) for the determination of the normalization factor were determined with reference to the transmittance characteristics in the wavelength range of 750 nm to 900 nm required for the optical filter. Thus, in the study for optimization of the material and conditions of the optical filter, a layer (light absorbing layer) of an appropriate thickness (for example, about 50 μm to about 100 μm) is formed using the material to be examined. It is efficient to normalize the transmittance spectrum measured about the layered product sample provided with the layer under predetermined conditions, and to evaluate the subject based on the result of the normalization. In the case of producing an optical filter to be put to practical use, the thickness of the layer may be adjusted so as to obtain a desired transmittance spectrum according to the materials and conditions under which a positive result is obtained in such evaluation. .

<Evaluation of incidence angle dependency of transmittance spectrum>
UV-visible spectrophotometer (Transmittance spectrum) when light in the wavelength range of 300 nm to 1200 nm is incident on the optical filters according to some examples and some comparative examples at incident angles of 0 ° and 40 ° Measured using JASCO Corporation, product name: V-670), and normalized as described above. Transmittance spectrum comparing the normalized transmission spectrum at 0 ° incidence angle with the normalized transmission spectrum at 40 ° incidence angle for each of some examples and some comparative examples Of the incident angle dependence of

Example 1
1.125 g of copper acetate monohydrate and 60 g of tetrahydrofuran (THF) were mixed and stirred for 3 hours to obtain a copper acetate solution. Next, 1.55 g of Plysurf A208F (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), which is a phosphoric acid ester compound, was added to the obtained copper acetate solution and stirred for 30 minutes to obtain a solution A. 10 g of THF was added to 0.4277 g of phenylphosphonic acid (manufactured by Nissan Chemical Industries, Ltd.) and stirred for 30 minutes to obtain a solution B-1. 10 g of THF was added to 0.2747 g of 4-bromophenylphosphonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and the mixture was stirred for 30 minutes to obtain a solution B-2. Next, while stirring solution A, solutions B-1 and B-2 were added to solution A, and stirred at room temperature for 1 minute. Next, after adding 28 g of toluene to this solution, it stirred at room temperature for 1 minute, and obtained C liquid. The solution C is placed in a flask and heated in an oil bath (manufactured by Tokyo Rika Kikai Co., Ltd., model: OSB-2100) while removing solvent for 18 minutes by a rotary evaporator (manufactured by Tokyo Rika Kikai Co., Ltd., model: N-1110SF) I did the processing. The set temperature of the oil bath was adjusted to 105 ° C. After that, the solution after desolvation was taken out of the flask. 4.400 g of silicone resin (Shin-Etsu Chemical Co., Ltd. product name: KR-300) was added to the taken-out solution, and it stirred at room temperature for 30 minutes, and obtained the light absorptive composition concerning Example 1. The addition amount of each material is shown in Table 1. The light absorbing composition according to Example 1 had high transparency, and in the light absorbing composition according to Example 1, the fine particles of the light absorbing agent were well dispersed.

  Using a dispenser in the range of about 30 mm × 30 mm at the center of one main surface of a transparent glass substrate (SCHOTT's product name: D263) made of borosilicate glass having dimensions of 76 mm × 76 mm × 0.21 mm About 0.3 g of the light absorbing composition according to Example 1 was applied to form a coating. Next, the transparent glass substrate having an undried coating film is put in an oven at 85 ° C. for 3 hours, then at 125 ° C. for 3 hours, then at 150 ° C. for 1 hour, then at 170 ° C. for 3 hours The coated film was heat-treated to cure the coated film, and an optical filter according to Example 1 provided with a light absorbing layer was produced. The transmittance spectra of the optical filter according to Example 1 normalized according to the above conditions (1) and (2) are shown in FIGS. 7A and 7B, respectively. Further, main values in the transmittance spectrum of the optical filter according to the first embodiment, which is normalized, are shown in Table 2. As shown in FIG. 7A, FIG. 7B, and Table 2, it was confirmed that the above conditions (I) to (V) were satisfied in the optical filter according to Example 1 provided with the light absorbing layer. Furthermore, as a result of comparison of the normalized transmittance spectrum at an incidence angle of 0 ° with the normalized transmittance spectrum at an incidence angle of 40 ° for the optical filter according to Example 1, the optical filter according to Example 1 The above conditions (VI) and (VII) were satisfied. It has been suggested that the optical filter according to Example 1 has desirable characteristics for use with an imaging device in an imaging device.

Example 2
1.125 g of copper acetate monohydrate and 60 g of THF were mixed and stirred for 3 hours to obtain a copper acetate solution. Next, 2.3382 g of Plysurf A208F (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), which is a phosphoric acid ester compound, was added to the obtained copper acetate solution and stirred for 30 minutes to obtain a solution A. Further, 10 g of THF was added to 0.5848 g of phenylphosphonic acid (manufactured by Nissan Chemical Industries, Ltd.) and stirred for 30 minutes to obtain a solution B. Next, the solution A was added to the solution A while stirring the solution A, and the solution was stirred at room temperature for 1 minute. Next, 45 g of toluene was added to this solution, followed by stirring at room temperature for 1 minute to obtain a solution C. The solution C is placed in a flask and heated in an oil bath (manufactured by Tokyo Rika Kikai Co., Ltd., model: OSB-2100) while removing the solvent for 25 minutes by a rotary evaporator (manufactured by Tokyo Rika Kikai Co., Ltd., model: N-1110SF) I did the processing. The set temperature of the oil bath was adjusted to 120 ° C. After that, the solution after desolvation was taken out of the flask. 4.400 g of silicone resin (Shin-Etsu Chemical Co., Ltd. product name: KR-300) was added to the solution taken out, and it stirred at room temperature for 30 minutes, and obtained the light absorptive composition concerning Example 2. The addition amount of each material is shown in Table 1. In the light absorbing composition according to Example 2, the fine particles of the light absorbing agent were well dispersed. In Plysurf A208F, in the above formulas (c1) and (c2), R ₂₁ , R ₂₂ and R ₃ are respectively the same type (CH ₂ CH ₂ O) _n R ₄ and R ₄ Is a phosphoric acid ester compound which is a monovalent group having 8 carbon atoms.

  An optical filter according to Example 2 was produced in the same manner as Example 1 except that the light absorbing composition according to Example 2 was used instead of the light absorbing composition according to Example 1. Main values in the transmittance spectrum of the optical filter according to Example 2 normalized according to the above conditions (1) and (2) are shown in Table 2. As shown in Table 2, in the optical filter according to Example 2 provided with the light absorption layer, it was confirmed that the above conditions (I) to (V) were satisfied. Furthermore, as a result of comparison between the normalized transmittance spectrum at an incidence angle of 0 ° and the normalized transmittance spectrum at an incidence angle of 40 ° for the optical filter according to Example 2, the optical filter according to Example 2 The above conditions (VI) and (VII) were satisfied. It has been suggested that the optical filter according to Example 2 has desirable characteristics for use with an imaging device in an imaging device.

Examples 3 to 18
Light absorbing compositions according to Examples 3 to 15 were obtained in the same manner as in Example 2 except that the amounts of phenylphosphonic acid and phosphoric acid ester compound (Plysurf A 208 F) were changed as shown in Table 1. Example 2 and Example 2 except that NIKKOL DDP-2 (manufactured by Nikko Chemicals Co., Ltd.) was used instead of Plysurf A208F as the phosphoric acid ester compound, and the addition amounts of phenylphosphonic acid and phosphoric acid ester compound were adjusted as shown in Table 1. Similarly, a light absorbing composition according to Example 16 was obtained. In NIKKOL DDP-2, in the above formulas (c1) and (c2), R ₂₁ , R ₂₂ and R ₃ are respectively the same kind of (CH ₂ CH ₂ O) _m R ₅ and m = 2 And R ₅ is a phosphoric acid ester compound which is a monovalent group having 12 to 15 carbon atoms. Example 2 was repeated except that NIKKOL DDP-6 (manufactured by Nikko Chemicals Co., Ltd.) was used instead of Plysurf A208F as the phosphoric acid ester compound, and the addition amounts of phenylphosphonic acid and phosphoric acid ester compound were adjusted as shown in Table 1. Similarly, a light absorbing composition according to Example 17 was obtained. In NIKKOL DDP-6, in the above formulas (c1) and (c2), R ₂₁ , R ₂₂ and R ₃ are respectively the same kind of (CH ₂ CH ₂ O) _m R ₅ and m = 6 And R ₅ is a phosphoric acid ester compound which is a monovalent group having 12 to 15 carbon atoms. A light absorbing composition according to Example 18 was obtained in the same manner as Example 2, except that the addition amounts of the phenylphosphonic acid and the phosphoric acid ester compound were adjusted as shown in Table 1. In the light absorbing compositions according to Examples 3 to 18, fine particles of the light absorbing agent were well dispersed.

  The optics according to Examples 3 to 18 are the same as Example 1, except that the light absorbing composition according to each of Examples 3 to 18 is used instead of the light absorbing composition according to Example 1. A filter was made. The main values in the transmittance spectrum of the optical filter according to Examples 3 to 18 normalized according to the above conditions (1) and (2) are shown in Table 2. As shown in Table 2, in the optical filters according to Examples 3 to 18 provided with the light absorption layer, it was confirmed that the above conditions (I) to (V) were satisfied. Furthermore, in each of the optical filters according to Examples 3 to 18, the comparison was performed between the normalized transmittance spectrum at an incidence angle of 0 ° and the normalized transmittance spectrum at an incidence angle of 40 °. The optical filters according to Examples 3 to 18 satisfied the conditions (VI) and (VII) described above. It has been suggested that the optical filters according to Examples 3 to 18 have desirable characteristics for use with an imaging device in an imaging device.

Examples 19 to 24
The light absorbing composition according to Example 1 was applied to one principal surface of a transparent glass substrate (manufactured by SCHOTT, product name: D263) made of borosilicate glass having dimensions of 76 mm × 76 mm × 0.21 mm. The transparent glass substrate having an undried coated film is put in an oven and coated at 85 ° C. for 3 hours, then at 125 ° C. for 3 hours, then at 150 ° C. for 1 hour, then at 170 ° C. for 8 hours Then, the coating was cured to obtain an optical filter according to Example 19 provided with a light absorbing layer. In addition, the thickness of the light absorption layer of the optical filter concerning Example 19 was adjusted so that the maximum value of the transmittance | permeability of the light in wavelength 750nm-900 nm might be 0.4-0.5%. Thus, based on the result of the transmittance spectrum of the optical filter according to Example 1 normalized by the above-mentioned condition (2), the thickness of the light absorption layer of the optical filter according to Example 19 was determined. Optical filters according to Examples 20, 21, 22, 23, and 24 in the same manner as Example 19 except that the light absorbing compositions according to Examples 2, 6, 13, 15, and 17 were used. I got The transmittance | permeability spectrum of the optical filter which concerns on Examples 19-24 is shown in FIGS. 8-13, respectively. Moreover, the main value regarding the transmittance | permeability of the optical filter which concerns on Examples 19-24, and the thickness of a light absorption layer are shown in Table 3. The thickness of the light absorbing layer was measured by a digital micrometer. The optical filters according to Examples 19 to 24 were confirmed to satisfy the conditions (I) to (V). In addition, according to Examples 19 to 24, it was suggested that the optical filter normalized by the condition (2) can be reproduced. It was suggested that the optical filters according to Examples 19 to 24 have desirable characteristics for use with an imaging device in an imaging device.

Example 25
Mix 0.1 g of OPTOOL DSX (manufactured by Daikin Industries, concentration of active ingredient: 20% by weight) and 19.9 g of a hydrofluoroether-containing solvent (manufactured by 3M, product name: Novec 7100) and stir for 5 minutes, A coating solution (concentration of active ingredient: 0.1% by weight) was prepared. This coating liquid is spin coated at a rotational speed of 3000 rpm on a transparent glass substrate (manufactured by SCHOTT, product name: D263 T eco) made of borosilicate glass having dimensions of 76 mm × 76 mm × 0.21 mm. A coating was formed. Thereafter, the coating was allowed to stand at room temperature for 24 hours to obtain a release film-attached glass.

  A square frame having an outer size of 70 mm × 70 mm, an inner size of 50 mm × 50 mm, a width of 10 mm, and a height of about 5 mm was disposed on the release film of the glass substrate with release film described above. This frame is made of a polyurethane resin (manufactured by Polycis, Asker C hardness: 15), taking care that air does not enter between the glass substrate and the frame made of polyurethane resin, while the glass substrate and the frame Made to stick. Next, a light absorbing composition prepared in the same manner as in Example 1 was applied to the inside of the frame using a dispenser to form a coating. Next, the glass substrate which has an undried coating film was put into oven, and the heat processing was performed at 85 degreeC for 3 hours. Thereafter, the glass substrate was taken out of the oven, and the frame was peeled off from the glass substrate, whereby the semifinished product of the optical filter formed on the inside of the frame and the frame were integrally peeled off from the substrate. Furthermore, the semifinished product of the optical filter is removed from the frame, and the semifinished product of the optical filter is placed in an oven and heat treated at 125 ° C. for 3 hours, 150 ° C. for 1 hour, and 170 ° C. for 3 hours, Cured completely. Thus, an optical filter according to Example 25 was obtained. The thickness of the optical filter according to Example 25 was 132 μm. The thickness of the optical filter according to Example 25 was measured by a digital micrometer.

  The transmittance spectrum of the optical filter according to Example 25 is shown in FIG. Moreover, the characteristic regarding conditions of said (I)-(V) of the transmittance | permeability spectrum of the optical filter which concerns on Example 25 read from this transmittance | permeability spectrum is shown in Table 4. FIG. The optical filter according to Example 25 satisfied the above conditions (I) to (V), and it was suggested that the optical filter has desirable characteristics for use with an imaging device in an imaging device. The above normalization is not performed in this transmittance spectrum.

<Comparative Examples 1 to 7>
The compositions according to Comparative Examples 1 and 2 were obtained in the same manner as Example 2, except that the addition amounts of the phenylphosphonic acid and the phosphoric acid ester compound were changed as shown in Table 5. Comparative Example in the same manner as Example 2 except that 4-bromophenylphosphonic acid was used instead of phenylphosphonic acid, and the addition amounts of 4-bromophenylphosphonic acid and phosphoric acid ester compound were adjusted as shown in Table 5. The composition according to 3 was obtained. The transparency of the compositions according to Comparative Examples 1 to 3 was low, and in the compositions according to Comparative Examples 1 to 3, the microparticles of copper phosphonate were not dispersed, and the microparticles of copper phosphonate were aggregated. The compositions according to Comparative Examples 1 to 3 were considerably difficult to use as light absorbing compositions, and it was not possible to produce an optical filter using the compositions according to Comparative Examples 1 to 3. From the contrast between the light absorbing composition according to Examples 1 to 18 and the composition according to Comparative Examples 1 to 3, the light absorbing composition containing a phosphonic acid represented by Formula (a) and a copper ion is included. In the light absorbing composition, the ratio of the content of phosphonic acid to the content of phosphoric acid ester is 0.10 to 0.48 on a mass basis, and the ratio of the content of phosphonic acid to the content of copper ions It was suggested that fine particles of the light absorbing agent tend to be well dispersed if the weight ratio of the substance is (0.45 to 0.80) based on the amount of substance (mol).

  Comparative Example 4 was carried out in the same manner as Example 2, except that n-butylphosphonic acid was used instead of phenylphosphonic acid, and the addition amounts of n-butylphosphonic acid and phosphoric acid ester compound were adjusted as shown in Table 5. The light absorbing composition was obtained. The light according to Comparative Examples 5 and 6 is the same as Example 2, except that hexyl phosphonic acid is used instead of phenyl phosphonic acid, and the addition amounts of hexyl phosphonic acid and phosphoric acid ester compound are adjusted as shown in Table 5. An absorbent composition was obtained. The light absorbability according to Comparative Example 7 is the same as in Example 2 except that ethylphosphonic acid is used instead of phenylphosphonic acid and the addition amounts of ethylphosphonic acid and phosphoric acid ester compound are adjusted as shown in Table 5. The composition was obtained. The light absorbing compositions according to Comparative Examples 4 to 7 have high transparency, and in the light absorbing compositions according to Comparative Examples 4 to 7, fine particles of the light absorbing agent were well dispersed.

  The optical filters according to Comparative Examples 4 to 7 are the same as in Example 1 except that the light absorbing compositions according to Comparative Examples 4 to 7 are used instead of the light absorbing composition according to Example 1. Made. Transmittance spectra of optical filters according to Comparative Examples 4 to 7 normalized according to the above conditions (1) and (2) are shown in FIGS. 15 to 18, respectively. In FIG. 15 to FIG. 18, the solid line graph indicates the transmittance spectrum normalized according to the condition (1), and the dashed line graph indicates the transmittance spectrum normalized according to the condition (2). Further, main values regarding the transmittance spectra of the optical filters according to Comparative Examples 4 to 7 normalized according to the above conditions (1) and (2) are shown in Table 6. None of the transmittance spectra of the optical filters according to Comparative Examples 4 to 7 normalized according to the above conditions (1) and (2) could simultaneously satisfy the above conditions (I) to (V) . In particular, in the transmittance spectra of the optical filters according to Comparative Examples 4 to 7, it was suggested that the IR cutoff wavelength tends to exist on the relatively long wavelength side and the UV cutoff wavelength tends to exist on the relatively short wavelength side.

  Light of the optical filter according to Comparative Examples 4 to 7 by increasing the concentration of the light absorbing agent (copper phosphonate) or increasing the thickness of the light absorbing layer in the light absorbing layer of the optical filter according to Comparative Examples 4 to 7 It is conceivable to increase the content of the light absorbing agent in the absorbing layer. In this case, the UV cutoff wavelength may be shifted to the long wavelength side while the IR cutoff wavelength is shifted to the short wavelength side in the transmittance spectrum of the optical filter, and the above conditions (IV) and (V) It seems to be advantageous to meet at the same time. However, when the content of the light absorbing agent in the light absorbing layer of the optical filter according to Comparative Examples 4 to 7 is increased, the transmittance in the visible light region is inevitably reduced, and the above conditions (I) to (I) It is quite difficult to satisfy V) at the same time.

  On the contrary, according to the embodiment, the range of design parameters that can be permitted to satisfy the above conditions (I) to (V) simultaneously is wide. As described above, according to the embodiment of the present invention supported by the examples, the degree of freedom in design of the optical filter satisfying the above conditions (I) to (V) is high.

1a to 1e Optical filter 2 Imaging device 3 Imaging lens 10 Light absorption layer 15 Auxiliary light absorption layer 20 Transparent dielectric substrate 30 Infrared reflection film 100 Imaging optical system

Claims (4)

Providing a substrate having a surface containing an organic fluorine compound and having a surface roughness Ra of 50 nm or less as defined in JIS B 0601: 1994;
A light absorber formed of a phosphonic acid and a copper ion represented by the following formula (a), a phosphate ester for dispersing the light absorber, and a curable resin, the light absorber being dispersed Applying the light absorbing composition on the surface of the substrate to form a coating, and curing the coating to form a light absorbing layer;
Peeling the light absorbing layer from the substrate;
In the light absorption layer, the ratio of the content of the phosphonic acid to the content of the phosphoric acid ester is 0.10 to 0.48 on a mass basis, and the ratio of the phosphonic acid to the content of the copper ion The content ratio is 0.45 to 0.80 based on the substance mass
Optical filter manufacturing method.

[Wherein, R ₁₁ is a phenyl group or a halogenated phenyl group in which at least one hydrogen atom in the phenyl group is substituted by a halogen atom]. ] The optical filter is
(I) having an average spectral transmittance of 80% or more at a wavelength of 450 nm to 600 nm,
(II) having a spectral transmittance of 1% or less at a wavelength of 750 nm to 900 nm,
(III) having an average spectral transmittance of 4% or less in the wavelength range of 350 nm to 370 nm,
In the optical filter,
(IV) A wavelength at which the spectral transmittance of the optical filter is 50% at a wavelength of 600 nm to 800 nm and having a spectral transmittance of 50% at a wavelength of 600 nm to 800 nm is defined as the infrared side cutoff wavelength The infrared side cutoff wavelength for light incident on the optical filter at an incident angle of 0 ° is 620 nm to 680 nm,
(V) A wavelength at which the spectral transmittance of the optical filter is 50% at a wavelength of 350 nm to 450 nm is defined as the ultraviolet side cutoff wavelength. The UV cut-off wavelength for light incident on the optical filter at an incident angle of 0 ° is 380 nm to 420 nm.
The method according to claim 1. A frame formed of a material having an Asker C hardness of 10 to 80 is disposed on the surface of the substrate,
Applying the light absorbing composition to the inside of the frame and onto the surface;
The manufacturing method of Claim 1 or 2. Heating the coating film on the substrate at a first temperature when forming the light absorption layer; and heating the light absorption layer separated from the substrate at a second temperature higher than the first temperature; The method according to any one of claims 1 to 3, further comprising

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