JPWO2019230570A1 - Near-infrared absorbing dye, optical filter and imaging device - Google Patents

Abstract

The present invention relates to a near-infrared absorbing dye composed of a compound represented by the formula (A1) and a near-infrared absorbing dye composed of a compound represented by the formula (A2). In formulas (A1) and (A2), R1, R2, R5 and R6 may independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a substituent, and may have a substituent between carbon atoms. It is an alkyl group, an alkoxy group, an aryl group or an alaryl group which may contain an unsaturated bond or an oxygen atom. R3, R4, R7 and R8 may each independently have a substituent and may contain an unsaturated bond, an oxygen atom, an alicyclic or an aromatic ring between carbon-carbon atoms in a linear or branched manner. It is a chain alkyl group. [Chemical 1]

Description

The present invention relates to a near-infrared absorbing dye, an optical filter, and an image pickup apparatus provided with the optical filter, which transmits light in the visible wavelength region and shields light in the near-infrared wavelength region.

An image sensor using a solid-state image sensor transmits light in the visible region (hereinafter also referred to as "visible light") and transmits light in the near infrared region (hereinafter "near red") in order to reproduce color tones well and obtain a clear image. A near-infrared cut filter that blocks (also called "outside light") is used. In the near-infrared cut filter, near-infrared light is shielded by an absorption layer in which a near-infrared absorbing dye is dispersed in a resin and a reflection layer made of a dielectric multilayer film that reflects near-infrared light.

As a near-infrared absorbing dye used for such a near-infrared cut filter, a dye having a squarylium skeleton and a heteroaromatic ring structure on both sides thereof is known. For example, Patent Document 1 describes a near-infrared absorbing dye having a heteroaryl ring containing chalcogen atoms on both sides of a squarylium skeleton and having an amino group bonded to the heteroaryl ring.

International Publication No. 2017/10423

Here, in the near-infrared absorbing dye used for the near-infrared cut filter, in order to sufficiently exhibit the optical characteristics of transmitting visible light and blocking near-infrared light in the absorbing layer containing the absorbing layer, the absorbing layer is provided. Solubility in the constituent resins is required. However, a near-infrared absorbing dye having both optical properties of transmitting visible light and shielding near-infrared light and sufficient solubility in a resin has not been obtained.

The present invention relates to a near-infrared absorbing dye, an optical filter, and an image pickup apparatus using the optical filter, which have both optical properties of transmitting visible light and blocking near-infrared light and high solubility in a resin. For the purpose of providing.

The present invention comprises a near-infrared absorbing dye composed of a compound represented by the formula (A1) (hereinafter, also referred to as a near-infrared absorbing dye (A1)) and a near-infrared absorbing dye composed of a compound represented by the formula (A2) (hereinafter, also referred to as a near-infrared absorbing dye). Also referred to as a near-infrared absorbing dye (A2)).

In formula (A1),
R ¹ and R ² may independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a substituent, and may contain an unsaturated bond or an oxygen atom between carbon atoms. It is an alkoxy group, an aryl group or an alaryl group. R ¹ and R ² may be linked to each other to form a 3- to 6-membered alicyclic or aromatic ring that may contain a heteroatom, in which case the hydrogen atom attached to the ring is substituted with a substituent. It may have been.
R ³ and R ⁴ may each independently have a substituent and may contain an unsaturated bond, an oxygen atom, an alicyclic or an aromatic ring between carbon atoms in a linear or branched chain form. It is an alkyl group of.

In formula (A2),
R ⁵ and R ⁶ may independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a substituent, and may contain an unsaturated bond or an oxygen atom between carbon atoms. Alkoxy group, aryl group or alaryl group,
R ⁷ and R ⁸ may each independently have a substituent and may contain an unsaturated bond, an oxygen atom, an alicyclic or an aromatic ring between carbon atoms in a linear or branched chain form. It is an alkyl group of.

Further, the optical filter according to the present invention is characterized by including an absorption layer containing the near-infrared absorbing dye (A1) or the near-infrared absorbing dye (A2) and a resin.
Further, the image pickup apparatus according to the present invention is characterized by including a solid-state image pickup device, an image pickup lens, and the above optical filter.

According to the present invention, it is possible to provide a near-infrared absorbing dye having optical properties of transmitting visible light and shielding near-infrared light and having high solubility in a resin. Further, according to the present invention, it is possible to provide an optical filter using the dye and an imaging device using the optical filter and having excellent color reproducibility.

FIG. 1 is a cross-sectional view schematically showing an example of an optical filter of the embodiment. FIG. 2 is a cross-sectional view schematically showing another example of the optical filter of the embodiment. FIG. 3 is a cross-sectional view schematically showing another example of the optical filter of the embodiment. FIG. 4 is a cross-sectional view schematically showing another example of the optical filter of the embodiment. FIG. 5 is a cross-sectional view schematically showing another example of the optical filter of the embodiment. FIG. 6 is a cross-sectional view schematically showing another example of the optical filter of the embodiment. FIG. 7 is a cross-sectional view schematically showing another example of the optical filter of the embodiment.

Hereinafter, embodiments of the present invention will be described.
In the present specification, the near-infrared absorbing dye may be abbreviated as "NIR dye" and the ultraviolet absorbing dye may be abbreviated as "UV dye".
In the present specification, the compound represented by the formula (A1) is referred to as a compound (A1). The same applies to compounds represented by other formulas. The NIR dye composed of the compound (A1) is also referred to as NIR dye (A1), and the same applies to other dyes. Further, for example, the group represented by the formula (1a) is also described as a group (1a), and the same applies to the groups represented by other formulas.
In the present specification, "~" representing a numerical range includes upper and lower limits.

<NIR dye>
The present invention provides the NIR dye (A1) represented by the formula (A1) and the NIR dye (A2) represented by the formula (A2).

The NIR dye (A1) of the present invention has a squarylium skeleton in the center of the molecular structure, and one thiophene ring is bound to each of the left and right sides of the squarylium skeleton, and the thiophene ring is located at the α position opposite to the squarylium skeleton. , An amino group having two linear or branched alkyl groups which may have a substituent and may contain an unsaturated bond, an oxygen atom, an alicyclic ring or an aromatic ring between carbon atoms (hereinafter referred to as an amino group). , "Amino group (X)") is bonded. The amino group (X) does not have a structure in which an aromatic ring is directly bonded to a nitrogen atom.

The NIR dye (A2) of the present invention has a squarylium skeleton in the center of the molecular structure, and one thienothiophene ring is bonded to each of the left and right sides of the squarylium skeleton, and the thienothiophene ring is α on the opposite side of the squarylium skeleton. It has a structure in which an amino group (X) is bonded to the position.

The NIR dye (A1) and the NIR dye (A2) are common in that they have a squarylium skeleton and an amino group (X). The NIR dye (A1) and the NIR dye (A2) are common in that the group connecting the squarylium skeleton and the amino group (X) contains a thiophene ring. Since the NIR dye (A1) and the NIR dye (A2) of the present invention have the structure, they have excellent optical properties of transmitting visible light and blocking near-infrared light, and also have high solubility in a resin.

In the NIR dye (A1) and the NIR dye (A2), the larger the number of rings containing the thiophene ring connecting the squarylium skeleton and the amino group (X), that is, the more the NIR dye (A2) is compared with the NIR dye (A1). The maximum absorption wavelength is larger. Therefore, it is possible to properly use the NIR dye according to the desired wavelength region.

Hereinafter, the NIR dye (A1) and the NIR dye (A2) will be described in detail. The NIR dye (A1) is represented by the following formula (A1).

In the formula (A1), R ¹ and R ² may independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a substituent, and have an unsaturated bond or an oxygen atom between carbon atoms. It may contain an alkyl group, an alkoxy group, an aryl group or an alaryl group. R ¹ and R ² may be linked to each other to form a 3- to 6-membered alicyclic or aromatic ring that may contain a heteroatom, in which case the hydrogen atom attached to the ring is substituted with a substituent. It may have been. Two of R ¹ in the formula (A1) may be different for the left and right squarylium skeleton, it is preferable that the left and right from the viewpoint of easy production of the same. The same applies to ^{R 2} and R ³ and R ^{4 described later.}

Here, in the present specification, unless otherwise specified, the alkyl group may be linear, branched, cyclic, or a structure in which these structures are combined. The alkyl group has an unsaturated bond between carbon atoms when it is linear or branched, or when it is cyclic and does not form an aromatic ring. Cycloalkene is an example in which the alkyl group is cyclic and has an unsaturated bond between carbon atoms but does not form an aromatic ring. The alkyl group has an oxygen atom between carbon atoms in any of linear, branched and cyclic cases. The same applies to the alkyl group contained in the alkoxy group. Further, the same applies to the alkyl group when the following aryl group has an alkyl group and the alkyl group of the alaryl group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a fluorine atom and a chlorine atom are preferable.

In the present specification, unless otherwise specified, the aryl group is bonded via a carbon atom constituting an aromatic ring of an aromatic compound, for example, a benzene ring, a naphthalene ring, a biphenyl, a furan ring, a thiophene ring, a pyrrole ring, or the like. Refers to the group to be used. The aryl group includes a structure in which a hydrogen atom bonded to a ring-constituting atom other than the carbon atom contributing to the bond is substituted with an alkyl group, for example, a tolyl group or a xsilyl group.

In the present specification, unless otherwise specified, an alaryl group refers to a group in which an alkyl group is bonded to an aromatic ring and is bonded via a carbon atom constituting the alkyl group. The alaryl group includes a structure in which a hydrogen atom bonded to a ring-constituting atom other than the atom to which the alkyl group contributing to the bond is bonded is substituted with an alkyl group.

Substituents in R ¹ and R ² include halogen atoms, hydroxyl groups, carboxy groups, sulfo groups, cyano groups, amino groups, N-substituted amino groups, nitro groups, alkoxycarbonyl groups, carbamoyl groups, and N-substituted carbamoyl groups. Examples thereof include an imide group and an alkoxy group having 1 to 20 carbon atoms. When R ¹ and R ² are aryl groups or alaryl groups, the substituent is a group that substitutes a hydrogen atom bonded to an aromatic ring or a hydrogen atom of an alkyl group contained therein, and is further an aryl group in addition to the above-mentioned substituent. including.

When R ¹ and R ² are an alkyl group or an alkoxy group, the number of carbon atoms is preferably 1 to 20, more preferably 1 to 15, and even more preferably 1 to 12. When R ¹ and R ² are aryl groups, the number of carbon atoms is preferably 6 to 20, more preferably 6 to 15, and even more preferably 6 to 12. When R ¹ and R ² are alaryl groups, the number of carbon atoms is preferably 7 to 20, more preferably 7 to 16, and even more preferably 7 to 13.
When R ¹ and R ² have a substituent, the carbon number includes the carbon number of the substituent.

From the viewpoint of photostability, R ¹ is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and a hydrogen atom is particularly preferable.

R ² is a linear or branched alkyl group having 3 to 20 carbon atoms which may contain an oxygen atom between carbon atoms from the viewpoint of visible light transmission and solubility in resins and solvents. Is preferable. The number of carbon atoms of the alkyl group is more preferably 3 to 12 in the case of a linear chain, and more preferably 4 to 10 in the case of a branched chain. R ² is, for example, more preferably groups selected from the group (1a) ~ (5a), group (1a) are particularly preferred. In particular, when ^{one or both of R 3} and R ⁴ are linear alkyl groups, R ² is preferably a branched chain alkyl group having 4 to 10 carbon atoms.

From the viewpoint of ease of production, R ² is preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and a hydrogen atom is particularly preferable.

R ¹ and R ² may be linked to each other to form an alicyclic or aromatic ring, in which case the number is 3-6. The number of members is the number of atoms containing two carbon atoms of the thiophene ring to which ^{R 1} and R ^{2 are bonded.} The alicyclic or aromatic ring may contain a heteroatom. Examples of the hetero atom include an oxygen atom, a nitrogen atom, and a sulfur atom. Further, the hydrogen atom bonded to the alicyclic or aromatic ring may be substituted with a substituent, and examples of the substituent include the substituent exemplified as the substituent in ^{R 1} and R ^2.

R ³ and R ⁴ may each independently have a substituent and may contain an unsaturated bond, an oxygen atom, an alicyclic or an aromatic ring between carbon atoms in a linear or branched chain form. It is an alkyl group of.

As the ^{substituents in R 3} and R ^4, the same substituents as the substituents in R ¹ and R ² , that is, halogen atom, hydroxyl group, carboxy group, sulfo group, cyano group, amino group, N-substituted amino group, Examples thereof include a nitro group, an alkoxycarbonyl group, a carbamoyl group, an N-substituted carbamoyl group, an imide group, and an alkoxy group having 1 to 20 carbon atoms.

Substituents in R ³ and R ⁴ further include cyclic alkyl or aryl groups. As the aryl group, a phenyl group which may have 1 to 5 substituents or a naphthyl group which may have 1 to 7 substituents is preferable. As the substituent which may substitute the hydrogen atom of the phenyl group and the naphthyl group, an alkyl group having 1 to 12 carbon atoms which may contain an unsaturated bond or an oxygen atom between carbon atoms, an alkoxy group, or an alkyl Amino groups (alkyl groups have 1 to 12 carbon atoms) can be mentioned. The phenyl group and the naphthyl group are preferably unsubstituted or substituted with 1 to 3 hydrogen atoms, and the substituent is preferably a methyl group, a tertiary butyl group, a dimethylamino group, a methoxy group or the like.

When R ³ and R ⁴ contain an alicyclic or aromatic ring in the main chain or side chain, it is preferable in terms of heat resistance and lengthening of the NIR absorption wavelength. When R ³ and R ⁴ do not have an alicyclic or aromatic ring in the main chain or side chain, they are preferable in terms of light resistance, ease of production, and solubility in resins and solvents. The number of carbon atoms in the alicyclic is preferably 3 to 10. The aromatic ring preferably has 4 to 14 carbon atoms.

Examples of the carbon number of R ³ and R ^{4 include 1 to 20.} The carbon number of R ³ and R ⁴ is preferably 2 to 20 in the case of a linear structure, more preferably 3 to 16, and even more preferably 4 to 12. The carbon number of R ³ and R ⁴ is preferably 3 to 20, more preferably 4 to 16, and even more preferably 8 to 10 in the case of a branched chain.
When R ³ and R ⁴ have a substituent, and when the main chain or side chain contains an alicyclic or an aromatic ring, the carbon number includes the carbon number of the substituent, the alicyclic ring, and the aromatic ring.

R ³ and R ⁴ may be the same or different, but are preferably the same from the viewpoint of ease of manufacture. From the viewpoint of solubility in the resin and the solvent, one of R ³ and R ⁴ is preferably in the form of a branched chain, and more preferably both are in the form of a branched chain.

When R ³ and R ⁴ are branched chains, the number of branches is not particularly limited. The number of branches is preferably 1 to 5, more preferably 1-3. From the viewpoint of solubility in the resin and the solvent, the branch position is preferably the α-position, and from the viewpoint of ease of production, the β-position is preferable. One carbon atom may be branched into two or three.

R ³ and R ⁴ are more preferably groups selected from, for example, groups (1b) to (5b).
-CH (C _n H _{2n + 1} ) ₂ ... (1b)
-C (C _n H _{2n + 1} ) ₃ ... (1c)
−CH ₂ −CH (C _n H _{2n + 1} ) ₂ … (2b)
−CH ₂ −C (C _n H _{2n + 1} ) ₃ … (2c)
− (CH ₂ ) ₂ −CH (C _n H _{2n + 1} ) ₂ … (3b)
− (CH ₂ ) ₃ −CH (C _n H _{2n + 1} ) ₂ … (4b)
− (CH ₂ ) _m −CH ₃ … (5b)

However, in the formulas (1b) to (4b), n is an integer of 1 to 10, preferably 2 to 8, and more preferably 4 to 6. _{The two or three C n} H _{2n + 1} in the formulas (1b) to (4b) may be linear or branched, and may be the same or different. In the formula (5b), m is an integer of 0 to 19, preferably 1 to 19, more preferably 2 to 15, and even more preferably 3 to 11. Further, the groups (1b) to (5b) may have an oxygen atom between carbon atoms.

Among these, the group (1b) and the group (1c) are preferable in terms of solubility because the branching position is at the α position. The group (2b) and the group (2c) are preferable in terms of ease of production because the branching position is at the β position, and the group (2b) is particularly preferable. As the group (2b), for example, one of the above group (3a) in which two _{(C n} H _{2n + 1} ) are CH _{3 and two (C n} H _{2n + 1} ) are C ₂ H ₅ and the other is C. is a ₄ H ₉ above group (1a) are preferred.

The NIR dye (A1), more ^{particularly,} R 1 to R ⁴ are tables compounds shown in 1 below (Table 1 also shows the abbreviations as its NIR dye (A1).) Can be mentioned. In Table 1, R ^{1 to} R ⁴ indicate the symbol of the formula when it is the group for which the formula is shown. In all the compounds shown in Table 1, R ^{1 to} R ⁴ are all the same on the left and right sides of the formula.

The NIR dye (A2) is represented by the following formula (A2).

In formula (A2), ^{R 5} may be similarly including preferred embodiments of ^{R 1} in the formula (A1). Further, R ^{6 is the same as R 2} in the formula (A1) including a preferable embodiment. ^{Furthermore, R 7} and R ⁸ in formula (A2) are ^{similar to R 3} and R ⁴ in formula (A1), including preferred embodiments.

The NIR dye (A2), more ^{specifically,} R 5 to R ⁸ is, Table 2 the compounds represented below (Table 2 also shows the abbreviations as its NIR dye (A2).) Can be mentioned. In Table 2, R ^{5 to} R ⁸ indicate the symbols of the formula when the formula is shown. In all the compounds shown in Table 2, R ^{5 to} R ⁸ are all the same on the left and right sides of the formula.

The NIR dye (A1) has a maximum absorption wavelength λ _max (A1) in a dichloromethane solution in the range of approximately 600 to 750 nm. The NIR dye (A1) has a transmittance of light having a wavelength of 418 nm and light having a wavelength of 482 nm when the concentration is adjusted so that the transmittance of light _{having a maximum absorption wavelength of λ max (A1) is 10% in a dichloromethane solution.} The transmittance of each of is preferably 85% or more, more preferably 90% or more, further preferably 92% or more, and particularly preferably 94% or more.

The NIR dye (A1) preferably has a steep slope of the spectral transmittance curve on the short wavelength side of the absorption peak having _{the maximum absorption wavelength λ max (A1) in the dichloromethane solution.} As a result, for example, in an optical filter provided with an absorption layer containing an NIR dye (A1) and a dielectric multilayer film, the effect of angle dependence in which the absorption wavelength shifts depending on the incident angle of light inherent in the dielectric multilayer film is affected. The absorption characteristics of the dielectric multilayer film can be fully utilized without being affected, and as a result, an optical filter having particularly excellent near-infrared shielding characteristics can be obtained.

Among the NIR dyes (A1) shown in Table 1, the NIR dyes (A1-1) and the like are preferable from the viewpoint of solubility.

The NIR dye (A2) has a maximum absorption wavelength λ _max (A2) in a dichloromethane solution in the range of approximately 700 to 850 nm. The NIR dye (A2) has a transmittance of light having a wavelength of 418 nm and light having a wavelength of 482 nm when the concentration is adjusted so that the transmittance of light _{having a maximum absorption wavelength of λ max (A2) is 10% in a dichloromethane solution.} The transmittance of each of is preferably 85% or more, more preferably 90% or more, further preferably 92% or more, and particularly preferably 94% or more.

The NIR dye (A2) has a maximum absorption wavelength λ _{max (A2)} in the dichloromethane solution in the above range. For example, in an optical filter provided with an absorption layer containing the NIR dye (A2) and a dielectric multilayer film. In a dielectric multilayer film, it is possible to effectively suppress light loss in which part of the near-infrared light that should obtain high reflectance with the incident angle has high transmittance, resulting in an optical filter with particularly excellent near-infrared shielding characteristics. be able to.

Among the NIR dyes (A2) shown in Table 2, the NIR dye (A2-1) and the like are preferable from the viewpoint of solubility.

The NIR dye (A1) and the NIR dye (A2) have good solubility in an organic solvent and good compatibility with a transparent resin. As a result, even if the absorption layer is made thin, it has excellent spectral transmittance characteristics, and the optical filter can be made thin, so that thermal expansion of the absorption layer due to heating can be suppressed. Therefore, for example, during heat treatment when forming a reflective layer laminated on the absorption layer or a functional layer such as an antireflection layer, it is possible to suppress the occurrence of cracks in those layers.

The NIR dye (A1) and the NIR dye (A2) are, for example, combined with 3,4-dihydroxy-3-cyclobutene-1,2-dione (squaric acid) and squaric acid to form the formula (A1) or the formula (A2). ) Can be reacted with a thiophene derivative capable of forming the structure shown in). For example, when the NIR dye (A1) and the NIR dye (A2) have a symmetrical structure, 2 equivalents of a thiophene derivative having a desired structure may be reacted with 1 equivalent of squaric acid in the above range.

Below, as a specific example, the reaction route for obtaining the NIR dye (A1) is shown. Squaric acid is indicated by (s) in the following scheme (F1). In scheme ^(F1), R 1 ~R ⁴ is the same meaning as ^R 1 to R ⁴ in the formula (A1).

According to the scheme (F1), a thiophene derivative having a bromine atom at the amino group introduction position and a desired substituent (R ¹ , R ^{2) at the β position is used as a starting material.}

The thiophene derivative of the starting material ^{is reacted with a tertiary amine having a desired substituent (R 3} , R ⁴ ) to form an intermediate A1-1 having a desired substituent (R ¹ , R ² , NR ³ R ⁴ ). Obtain a thiophene derivative. Two equivalents of intermediate A1-1 are reacted with one equivalent of squaric acid (s) to give the NIR dye (A1).

The NIR dye (A2) can be produced by the following scheme (F2). Squaric acid is indicated by (s) in the following scheme (F2). In scheme (F2), R ^{5 to} R ⁸ have the same meaning as ^{R 5 to} R ⁸ in formula (A2).

In scheme (F2), intermediate was introduce a desired substituent ^{(R 5,} R ⁶⁾ is reacted with thieno thiophene derivative amino group introduction position to N- bromosuccinimide (NBS) having in bromine in β-position A2 Get -1.

Intermediate A2-1 is reacted with a tertiary amine having a desired substituent (R ⁷ , R ^{8 ) to obtain the desired substituent (R 5} , R ⁶ , NR ⁷ R ⁸ ) as intermediate A2-2. Obtain a thienothiophene derivative. The NIR dye (A2) is obtained by reacting 1 equivalent of squaric acid (s) with 2 equivalents of intermediate A2-2.

The use of the NIR dye (A1) and the NIR dye (A2) of the present invention is not particularly limited. For example, it can be applied to an optical filter that shields near-infrared light.

<Optical filter>
The optical filter of one embodiment of the present invention (hereinafter, also referred to as “the present filter”) includes an absorption layer containing the NIR dye (A1) or the NIR dye (A2) of the present invention and a resin. In this filter, the absorption layer may contain two or more kinds selected from NIR dye (A1) and NIR dye (A2). In the following description, a NIR dye consisting of one or more selected from NIR dye (A1) and NIR dye (A2) is referred to as NIR dye (A).

In addition to the absorption layer, the filter may further have a reflection layer made of a dielectric multilayer film. In the following description, the "reflective layer" refers to a reflective layer made of a dielectric multilayer film.

The filter may further have a transparent substrate. In this case, the absorption layer is provided on the main surface of the transparent substrate. When the filter has a transparent substrate and an absorption layer and a reflection layer, the absorption layer and the reflection layer are provided on the main surface of the transparent substrate. The present filter may have the absorption layer and the reflection layer on the same main surface of the transparent substrate, or may have the absorption layer and the reflection layer on different main surfaces. When the absorption layer and the reflection layer are provided on the same main surface, the stacking order thereof is not particularly limited.

The filter may also have other functional layers. Examples of other functional layers include an antireflection layer that suppresses the loss of visible light transmittance. In particular, when the absorption layer has the outermost surface structure, a visible light transmittance loss due to reflection occurs at the interface between the absorption layer and air, so it is preferable to provide an antireflection layer on the absorption layer.

Next, a configuration example of this filter will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an optical filter 10A composed of an absorption layer 11. The absorption layer 11 can be composed of a layer containing the NIR dye (A) and the resin. In the optical filter 10A, the absorption layer 11 can take the form of a film or a substrate.

FIG. 2 is a configuration example of the optical filter 10B having the reflection layer 12 on one main surface of the absorption layer 11. In the optical filter 10B, the absorption layer 11 can be composed of a layer containing the NIR dye (A) and the resin. The phrase "providing the reflective layer 12 on one main surface (upper) of the absorbent layer 11" is not limited to the case where the reflective layer 12 is provided in contact with the absorbent layer 11, and the absorbent layer 11 and the reflective layer 12 The same applies to the following configurations, including the case where another functional layer is provided between the two.

FIG. 3 is a cross-sectional view schematically showing an example of an optical filter of the embodiment having a transparent substrate and an absorption layer. FIG. 4 is a cross-sectional view schematically showing an example of an optical filter of an embodiment having a transparent substrate, an absorption layer, and a reflection layer. The optical filter 10C has an absorption layer 11 arranged on one main surface of the transparent substrate 13 and the transparent substrate 13. The optical filter 10D has an absorption layer 11 arranged on one main surface of the transparent substrate 13 and the transparent substrate 13, and a reflection layer 12 provided on the other main surface of the transparent substrate 13. In the optical filters 10C and 10D, the absorption layer 11 can be composed of a layer containing the NIR dye (A) and the resin.

FIG. 5 shows an optical filter 10E having an absorbing layer 11 on one main surface of the transparent substrate 13 and reflecting layers 12a and 12b on the other main surface of the transparent substrate 13 and on the main surface of the absorbing layer 11. This is a configuration example. FIG. 6 is a configuration example of an optical filter 10F having absorption layers 11a and 11b on both main surfaces of the transparent substrate 13 and further having reflection layers 12a and 12b on the main surfaces of the absorption layers 11a and 11b.

In FIGS. 5 and 6, the two reflective layers 12a and 12b to be combined may be the same or different. For example, the reflecting layers 12a and 12b have a property of reflecting ultraviolet light and near-infrared light and transmitting visible light, and the reflecting layer 12a reflects ultraviolet light and light in the first near-infrared region. The reflective layer 12b may be configured to reflect ultraviolet light and light in the second near-infrared region.

Further, in FIG. 6, the two absorption layers 11a and 11b may be the same or different. When the absorption layers 11a and 11b are different, for example, the absorption layers 11a and 11b may be a combination of a near-infrared absorbing layer and an ultraviolet absorbing layer, or may be a combination of an ultraviolet absorbing layer and a near-infrared absorbing layer, respectively. The near-infrared absorbing layer can be composed of a layer containing the NIR dye (A) and a resin.

FIG. 7 is a configuration example of the optical filter 10G provided with the antireflection layer 14 on the main surface of the absorption layer 11 of the optical filter 10D shown in FIG. The antireflection layer 14 may cover not only the outermost surface of the absorption layer 11 but also the entire side surface of the absorption layer 11. In that case, the moisture-proof effect of the absorption layer 11 can be enhanced.

Hereinafter, the absorption layer, the reflection layer, the transparent substrate, and the antireflection layer will be described.
(Absorption layer)
The absorption layer contains the NIR dye (A). The absorption layer may further contain an NIR dye other than the NIR dye (A) (hereinafter, referred to as another NIR dye) as long as the effect of the present invention is not impaired.

The content of the NIR dye (A) in the absorption layer is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the resin in the total amount of the NIR dye (A) and other NIR dyes. A desired near-infrared absorbing ability is obtained at 0.1 parts by mass or more, and a decrease in near-infrared absorbing ability and an increase in haze value are suppressed at 30 parts by mass or less. The total content of the NIR dye (A) and other NIR dyes is more preferably 0.5 to 25 parts by mass, and even more preferably 1 to 20 parts by mass.

Other NIR dyes have a maximum absorption wavelength in the range of 660 to 1100 nm, and there is a predetermined difference between _{the maximum absorption wavelength and the maximum absorption wavelength λ max (A) of the NIR dye (A).} preferable. The difference between the two maximum absorption wavelengths is preferably 30 nm or more, more preferably 50 nm or more, further preferably 80 nm or more, and particularly preferably 100 nm or more.

Other NIR dyes include cyanine compounds, phthalocyanine compounds, naphthalocyanine compounds, dithiol metal complex compounds, diimonium compounds, polymethine compounds, phthalide compounds, naphthoquinone compounds, anthraquinone compounds, and indophenol compounds. And squarylium compounds other than NIR dye (A) can be mentioned. As the other NIR dyes, one type may be used alone, or two or more types may be mixed and used.

The absorption layer contains a NIR dye (A) and a resin, and is typically a layer or a (resin) substrate in which the NIR dye (A) is uniformly dissolved or dispersed in the resin. The resin is usually a transparent resin, and the absorption layer may contain other NIR dyes in addition to the NIR dye (A). Further, the absorption layer may contain a dye other than the NIR dye, particularly a UV dye.

Specific examples of the UV dye include oxazole-based, merocyanine-based, cyanine-based, naphthalimide-based, oxadiazole-based, oxazine-based, oxazolidine-based, naphthalic acid-based, styryl-based, anthracene-based, cyclic carbonyl-based, and triazole-based. Pigments can be mentioned. Of these, oxazole-based and merocyanine-based pigments are preferable. In addition, one type of UV dye may be used alone for the absorption layer, or two or more types may be used in combination.

As the transparent resin, acrylic resin, epoxy resin, en-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyether sulfone resin, polyparaphenylene resin, polyarylene ether phosphine oxide resin, polyimide Examples thereof include resins, polyamideimide resins, polyolefin resins, cyclic olefin resins, and polyester resins such as polyethylene terephthalate resins and polyethylene naphthalate resins. One of these resins may be used alone, or two or more of these resins may be mixed and used.

The transparent resin is preferably a resin having a high glass transition point (Tg) from the viewpoints of transparency, solubility of the NIR dye (A), and heat resistance. Specifically, one or more selected from polyester resin, polycarbonate resin, polyether sulfone resin, polyarylate resin, polyimide resin, and epoxy resin is preferable, and one or more selected from polyester resin and polyimide resin is more preferable. ..

The absorption layer further comprises an adhesion imparting agent, a color tone correcting dye, a leveling agent, an antistatic agent, a heat stabilizer, a light stabilizer, an antioxidant, a dispersant, a flame retardant, as long as the effects of the present invention are not impaired. It may have an optional component such as a lubricant or a plasticizer.

For the absorption layer, for example, a dye containing the NIR dye (A), a resin or a raw material component of the resin, and each component to be blended as needed are dissolved or dispersed in a solvent to prepare a coating liquid. This can be applied to a substrate, dried, and further cured if necessary to form the substrate. The base material may be a transparent substrate arbitrarily included in the present filter, or may be a peelable base material used only when forming an absorption layer. The solvent may be a dispersion medium that can be stably dispersed or a solvent that can be dissolved.

Further, the coating liquid may contain a surfactant in order to improve voids due to minute bubbles, dents due to adhesion of foreign substances, repellency in the drying step, and the like. Further, for the coating of the coating liquid, for example, a dip coating method, a cast coating method, a spin coating method or the like can be used. An absorption layer is formed by applying the above coating liquid on a substrate and then drying it. When the coating liquid contains a raw material component of a resin, further curing treatments such as thermosetting and photocuring are performed.

Further, the absorption layer can be manufactured in the form of a film by extrusion molding, and this film may be laminated on another member and integrated by thermocompression bonding or the like. For example, when the filter includes a transparent substrate, this film may be attached onto the transparent substrate.

This filter may have two or more absorption layers. When the absorption layer is composed of two or more layers, each layer may be the same or different. When the absorption layer has two or more layers, there is an example in which one layer is a near-infrared absorption layer made of a resin containing a NIR dye and the other layer is an ultraviolet absorption layer made of a resin containing a UV dye. .. Further, the absorption layer itself may be a substrate (resin substrate).

In this filter, the thickness of the absorption layer is preferably 0.1 to 100 μm. When the absorption layer is composed of a plurality of layers, the total thickness of each layer is preferably 0.1 to 100 μm. If the thickness is less than 0.1 μm, the desired optical characteristics may not be sufficiently exhibited, and if the thickness is more than 100 μm, the flatness of the layer may be lowered and the absorption rate may vary in the plane. The thickness of the absorption layer is more preferably 0.3 to 50 μm. Further, when another functional layer such as a reflective layer or an antireflection layer is provided, cracks or the like may occur if the absorbing layer is too thick depending on the material thereof. Therefore, the thickness of the absorption layer is more preferably 0.3 to 10 μm.

(Transparent board)
The transparent substrate is an arbitrary component in this filter. When the present filter includes a transparent substrate, the thickness of the transparent substrate is preferably 0.03 to 5 mm, and more preferably 0.05 to 1 mm from the viewpoint of thinning. As the material of the transparent substrate, glass, (birefringent) crystal, or resin can be used as long as it transmits visible light.

As the glass for the transparent substrate, absorption type glass (near infrared absorption glass base material) in which CuO or the like is added to fluoride-based glass, phosphate-based glass, etc., soda lime glass, borosilicate glass, non-alkali glass, etc. , Quartz glass and the like. The "phosphate glass" also includes a silicate glass in which a part of the skeleton of the _{glass is composed of SiO 2.}

When the transparent substrate is fluorinated glass, specifically, in cation% display, P ⁵⁺ : 20 to 45%, Al ³⁺ : 1 to 25%, R ⁺ : 1 to 30% (however, R ⁺ is Li ^At least one of +, Na ⁺ , and K ⁺ , and the value on the left is the total value of the respective contents), Cu ²⁺ : 1 to 20%, R ²⁺ : 1 to 50% (provided that , R ²⁺ is ^{at least one of Mg 2+} , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , and Zn ²⁺ , and the value on the left is the total value of each content) and anion. In% representation, ^{it preferably contains F −} : 10 to 65% and O ² : 35 to 90%.

When the transparent substrate is phosphate glass, P ₂ O ₅ : 30 to 80%, Al ₂ O ₃ : 1 to 20%, R ₂ O: 0.5 to 30%, in terms of mass%, ( However, R ₂ O is _{at least one of Li 2} O, Na ₂ O, and K ₂ O, and the value on the left is the total value of the respective contents), CuO: 1 to 1. 12%, RO: 0.5 to 40% (However, RO is at least one of MgO, CaO, SrO, BaO, and ZnO, and the value on the left is the total value of the respective contents. Is).

Examples of commercially available products include NF-50E, NF-50EX, NF-50T, NF-50TX, NF-50GX (manufactured by AGC Co., Ltd., trade name), etc., BG-60, BG-61 (all manufactured by Shot Co., Ltd.). , Product name), etc., CD5000 (manufactured by HOYA Corporation, product name) and the like.

The CuO-containing glass described above may further contain a metal oxide. When one or more of, for example, Fe ₂ O ₃ , MoO ₃ , WO ₃ , CeO ₂ , Sb ₂ O ₃ , V ₂ O _5, etc. are contained as the metal oxide, the CuO-containing glass has an ultraviolet absorbing property. Have. The content of these metal oxides, relative to the CuO-containing glass 100 parts by _weight, the _{Fe 2 O 3, MoO 3,} WO 3 and at least one selected from the group consisting of CeO _{2, Fe} 2 _{O 3} : 0.6 to 5 parts by mass, MoO ₃ : 0.5 to 5 parts by mass, WO ₃ : 1 to 6 parts by mass, CeO ₂ : 2.5 to 6 parts by mass, or Fe ₂ O ₃ and Sb ₂ O ₃ of the two _Fe 2 _O 3: 0.6 to 5 parts by mass ₊ Sb ₂ O 3: _0.1~5 parts by weight, or _V 2 _{O 5} and the two CeO _{2 V 2 O} 5: 0.01~ 0.5 parts by mass + CeO ₂ : 1 to 6 parts by mass is preferable.

As the transparent resin for the transparent substrate, acrylic resin, epoxy resin, en-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyether sulfone resin, polyparaphenylene resin, polyarylene ether phosphine Examples thereof include oxide resins, polyimide resins, polyamideimide resins, polyolefin resins, cyclic olefin resins, and polyester resins such as polyethylene terephthalate resins and polyethylene naphthalate resins. One of these resins may be used alone, or two or more of these resins may be mixed and used.

(Reflective layer)
The reflective layer is an arbitrary component in this filter. The reflective layer is made of a dielectric multilayer film and has a function of shielding light in a specific wavelength range. Examples of the reflective layer include those having wavelength selectivity that transmits visible light and mainly reflects light having a wavelength other than the light-shielding region of the absorption layer. In this case, the reflection region of the reflection layer may include a light-shielding region in the near-infrared region of the absorption layer. The reflective layer is not limited to the above characteristics, and may be appropriately designed according to specifications for shielding light in a predetermined wavelength range.

When the present filter is provided with a reflective layer, it is preferable that the NIR dye (A) has a reflective property having a transmittance of 1% or less in light having _{a maximum absorption wavelength λ max (A).} As a result, this filter synergistically obtains high light-shielding property (high OD value) at _{the maximum absorption wavelength λ max (A) of the NIR dye (A).}

This filter may have one reflective layer or two or more reflective layers. When the reflective layer is composed of two or more layers, each layer may be the same or different. When the number of reflective layers is two or more, one layer shields at least near-infrared light, particularly, a near-infrared shielding layer having the above-mentioned reflective characteristics, and the other layer shields at least ultraviolet light. A combination of an ultraviolet shielding layer may be used.

The reflective layer is composed of a dielectric multilayer film in which a low refractive index dielectric film (low refractive index film) and a high refractive index dielectric film (high refractive index film) are alternately laminated. Examples of the material of the high refractive index film include Ta ₂ O ₅ , TiO ₂ , and Nb ₂ O ₅ . _{Of these, TiO 2} is preferable from the viewpoints of film formation property, reproducibility in refractive index and the like, stability and the like. Examples of the material of the low refractive index film include SiO ₂ , SiO _x N _{y and the} like. _{SiO 2} is preferable from the viewpoint of reproducibility, stability, economy and the like in terms of film forming property. The film thickness of the reflective layer is preferably 2 to 10 μm.

(Anti-reflective layer)
Examples of the antireflection layer include a dielectric multilayer film, an intermediate refractive index medium, and a moth-eye structure in which the refractive index gradually changes. Above all, the use of a dielectric multilayer film is preferable from the viewpoint of high light utilization efficiency and productivity.

By having an absorption layer containing the NIR dye (A), this filter can realize excellent light-shielding property against near-infrared light and can realize high visible light transmission. This filter can be used, for example, in an imaging device such as a digital still camera, an ambient light sensor, or the like.

An image pickup device using this filter includes a solid-state image pickup device, an image pickup lens, and this filter. This filter can be used, for example, by being arranged between an image pickup lens and a solid-state image sensor, or by being directly attached to a solid-state image sensor, an image sensor, or the like of an image pickup device via an adhesive layer.

Next, the present invention will be described in more detail with reference to Examples. First, in Examples 1 and 2, the NIR dyes (A1-1) and NIR dyes (A2-1) shown in Tables 1 and 2, respectively, were produced. Further, in Examples 3 and 4, NIR dyes (Acf1) and NIR dyes (Acf2) of Comparative Examples having different structures from the NIR dye (A) were produced. The optical characteristics of the obtained NIR dye were measured and evaluated.

In addition, an example (Example 5) of an optical filter having an absorption layer containing the obtained NIR dye will be described.

In each of the following examples, the structure of the produced NIR dye was confirmed by 1H NMR. An ultraviolet-visible spectrophotometer (U-4150 type manufactured by Hitachi High-Technologies Corporation) was used to evaluate the optical characteristics of the NIR dye and the absorption layer containing the NIR dye.

[Example 1]
NIR dye (A1-1) was synthesized according to the reaction pathway shown below.

<Step A1-1-1>
2-Bromothiophene (2.00 g, 12.3 mmol) and shaving magnesium (0.597 g, 24.6 mmol) were placed in a flask and dissolved in anhydrous tetrahydrofuran (18 ml) under a nitrogen atmosphere. The solution was refluxed for 3 hours and cooled to −40 ° C. In a separate flask, N-chlorosuccinimide (1.64 g, 12.3 mmol) was dissolved in anhydrous toluene (31 ml) under a nitrogen atmosphere, and bis- (2-ethylhexyl) amine (2.96 g, 12.3 mmol) was added. , Stirred for 20 minutes. Tetraisopropyl orthotitamate (3.49 g, 12.3 mmol) was added dropwise to a mixed solution cooled to -40 ° C, and the mixture was stirred for 5 minutes, followed by mixing N-chlorosuccinimide and bis- (2-ethylhexyl) amine. The solution was added dropwise. The mixture was stirred at room temperature for 3 hours, and after completion of the reaction, a saturated aqueous potassium carbonate solution (25 ml) was added. It was subsequently diluted with ethyl acetate and filtered, and the resulting solution was extracted with ethyl acetate. The obtained organic layer was washed with saturated brine, the solvent was removed, and intermediate A1-1-1 (1.00 g, yield 25%) was obtained by silica gel column chromatography (hexane: triethylamine = 100: 3). Obtained.

<Step A1-1-2>
Intermediate A1-1-1 (1.00 g, 3.09 mmol) obtained in step A1-1-1 in a flask, 3,4-dihydroxy-3-cyclobutene-1,2-dione (0.176 g, 1). .55 mmol) was added and dissolved in a mixed solution of normal butanol (8 ml) and toluene (8 ml) under a nitrogen atmosphere. The mixture was stirred under reflux for 3 hours, and after completion of the reaction, the solvent was removed to obtain NIR dye (A1-1) (0.570 g, yield 51%) by silica gel chromatography (dichloromethane: methanol = 20: 1). ..

[Example 2]
NIR dye (A2-1) was synthesized according to the reaction pathway shown below.

<Step A2-1-1>
Thieno [3,2-b] thiophene (4.00 g, 28.5 mmol) was placed in a flask and dissolved in anhydrous dimethylformamide (28.5 ml) under a nitrogen atmosphere. The above solution was cooled to −15 ° C., and an anhydrous dimethylformamide solution (28.5 ml) in which N-bromosuccinimide (5.08 g, 28.5 mmol) was dissolved was added dropwise. The mixture was stirred at room temperature for 30 minutes and then at 60 ° C. for 5 hours. After completion of the reaction, the mixture was poured into ice water and extracted with diisopropyl ether. The obtained organic layer was washed with saturated brine to remove the solvent, and then intermediate A2-1-1 (5.09 g, yield 81%) was obtained by silica gel column chromatography (hexane).

<Step A2-1-2>
Intermediate A2-1-1 (2.00 g, 9.13 mmol) obtained in step A2-1-1 and shaving magnesium (0.440 g, 18.3 mmol) were placed in a flask, and anhydrous tetrahydrofuran was added under a nitrogen atmosphere. It was dissolved in (13 ml). The solution was refluxed for 3 hours and cooled to −40 ° C. In a separate flask, N-chlorosuccinimide (0.490 g, 3.65 mmol) was dissolved in anhydrous toluene (18 ml) under a nitrogen atmosphere, and bis- (2-ethylhexyl) amine (0.880 g, 3.65 mmol) was added. , Stirred for 20 minutes.

Tetraisopropyl orthotitamate (2.59 g, 9.13 mmol) was added dropwise to the mixed solution cooled to -40 ° C, and the mixture was stirred for 5 minutes, followed by mixing N-chlorosuccinimide and bis- (2-ethylhexyl) amine. The solution was added dropwise. The mixture was stirred at room temperature for 3 hours, and after completion of the reaction, a saturated aqueous potassium carbonate solution (18 ml) was added. It was subsequently diluted with ethyl acetate and filtered, and the resulting solution was extracted with ethyl acetate. The obtained organic layer was washed with saturated brine, the solvent was removed, and intermediate A2-1-2 (0.987 g, yield 28%) was obtained by silica gel column chromatography (hexane: triethylamine = 100: 3). Obtained.

<Step A2-1-3>
Intermediate A2-1-2 (0.411 g, 1.08 mmol) obtained in step A2-1-2, 3,4-dihydroxy-3-cyclobutene-1,2-dione (0.0617 g, 0) in a flask. .541 mmol) was added and dissolved in a mixed solution of normal butanol (3 ml) and toluene (3 ml) under a nitrogen atmosphere. The mixture was stirred under reflux for 3 hours, and after completion of the reaction, the solvent was removed to obtain NIR dye (A2-1) (0.100 g, yield 22%) by silica gel chromatography (dichloromethane: methanol = 50: 1). ..

[Example 3]
The NIR dye (Acf1) was synthesized according to the reaction pathway shown below.

<Step Acf1-1>
Ditieno [3,2-b: 2', 3'-d] thiophene (2.00 g, 10.2 mmol) was placed in a flask and dissolved in anhydrous dimethylformamide (10 ml) under a nitrogen atmosphere. The above solution was cooled to −15 ° C., and an anhydrous dimethylformamide solution (10 ml) in which N-bromosuccinimide (1.81 g, 10.2 mmol) was dissolved was added dropwise. The mixture was stirred at room temperature for 30 minutes and then at 60 ° C. for 5 hours. After completion of the reaction, the mixture was poured into ice water and extracted with diisopropyl ether. The obtained organic layer was washed with saturated brine to remove the solvent, and then the intermediate Acf1-1 (2.58 g, yield 92%) was obtained by silica gel column chromatography (dichloromethane).

<Step Acf1-2>
The intermediate Acf1-1 (2.57 g, 9.34 mmol) obtained in step Acf1-1 and shaving magnesium (0.450 g, 18.7 mmol) were placed in a flask and placed in anhydrous tetrahydrofuran (13 ml) under a nitrogen atmosphere. Dissolved. The solution was refluxed for 3 hours and cooled to −40 ° C. In a separate flask, N-chlorosuccinimide (1.25 g, 9.34 mmol) was dissolved in anhydrous toluene (23 ml) under a nitrogen atmosphere, and bis- (2-ethylhexyl) amine (2.26 g, 9.34 mmol) was added. , Stirred for 20 minutes.

Tetraisopropyl orthotitamate (2.65 g, 9.34 mmol) was added dropwise to the mixed solution cooled to -40 ° C, and the mixture was stirred for 5 minutes, followed by mixing N-chlorosuccinimide and bis- (2-ethylhexyl) amine. The solution was added dropwise. The mixture was stirred at room temperature for 3 hours, and after completion of the reaction, a saturated aqueous potassium carbonate solution (18 ml) was added. It was subsequently diluted with ethyl acetate and filtered, and the resulting solution was extracted with ethyl acetate. The obtained organic layer was washed with saturated brine, the solvent was removed, and intermediate Acf1-2 (1.02 g, yield 25%) was obtained by silica gel column chromatography (hexane: triethylamine = 100: 3). ..

<Step Acf1-2>
In a flask, add the intermediate Acf1-2 (1.02 g, 2.35 mmol) obtained in step Acf1-2 and 3,4-dihydroxy-3-cyclobutene-1,2-dione (0.134 g, 1.17 mmol). And dissolved in a mixed solution of normal butanol (6 ml) and toluene (6 ml) under a nitrogen atmosphere. The mixture was stirred under reflux for 3 hours, the solvent was removed after the reaction was completed, and the dye (Acf1) (0.569 g, yield 51%) was obtained by silica gel chromatography (hexane: ethyl acetate: triethylamine = 100: 1: 3). Obtained.

[Example 4]
The NIR dye (Acf2) was synthesized according to the reaction pathway shown below.

<Step Acf2-1>
In a flask, 3-bromothieno [3,2-b] thiophene (3 g, 13.7 m mmol), [1,1'-bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct (0.0447 g, 0. 0548 mmol) was added, and the mixture was dissolved in a tetrahydrofuron solution (41 ml, 20.6 mmol) of 0.5 M isobutylzinc bromide under a nitrogen atmosphere, and the mixture was stirred with reflux for 24 days. After completion of the reaction, a saturated aqueous solution of ammonium chloride was added and extracted with diisopropyl ether to obtain an organic layer. The organic layer was washed with 5% aqueous hydrochloric acid solution, then with saturated brine, and the solvent was removed to obtain intermediate Acf2-1 (2.32 g, 58%) by silica gel column chromatography (hexane). ..

<Step Acf2-2>
The intermediate Acf2-1 (2.32 g, 11.8 mmol) obtained in step Acf2-1 was placed in a flask and dissolved in anhydrous dimethylformamide (12 ml) under a nitrogen atmosphere. The above solution was cooled to −15 ° C., and an anhydrous dimethylformamide solution (12 ml) in which N-bromosuccinimide (4.63 g, 26.0 mmol) was dissolved was added dropwise. The mixture was stirred at room temperature for 30 minutes and then at 60 ° C. for 5 hours. After completion of the reaction, the mixture was poured into ice water and extracted with diisopropyl ether. The obtained organic layer was washed with saturated brine to remove the solvent, and then the intermediate Acf2-2 (3.55 g, yield 85%) was obtained by silica gel column chromatography (hexane).

<Step Acf2-3>
Palladium acetate (II) (0.111 g, 0.0.494 mmol), sodium tertiary buttoxide (1.92 g, 20.0 mmol), and triterchary butylphosphine (0.200 g, 0.991 mmol) were placed in a flask. It was dissolved in anhydrous toluene (15 ml) under a nitrogen atmosphere. The mixed solution was stirred at 60 ° C. for 10 minutes and returned to room temperature with 4,4'-dinormal octyldiphenylamine (3.94 g, 10.0 mmol) and the intermediate Acf2-2 obtained in step Acf2-2 (). A mixed solution prepared by dissolving 3.55 g (10.0 mmol) in anhydrous toluene (4 ml) was added dropwise, and the mixture was stirred under reflux for 3 hours. After completion of the reaction, the solvent was removed from the filtrate obtained by filtration, and intermediate Acf2-3 (1.56 g, 23%) was obtained by silica gel column chromatography (hexane).

<Step Acf2-4>
Intermediate Acf2-3 (1.56 g, 2.35 mmol) obtained in step Acf2-3, palladium (II) acetate (0.0269 g, 0.120 mmol), xantphos (0.102 g, 0.176 mmol) in a flask. , Triethylsilane (3.58 g, 30.8 mmol) was added and dissolved in anhydrous toluene (23 ml) under a nitrogen atmosphere. The mixed solution was refluxed and stirred for 7 hours. After completion of the reaction, the solvent was removed to obtain intermediate Acf2-4 (1.16 g, 84%) by silica gel column chromatography (hexane).

<Step Acf2-5>
The flask is filled with the intermediate Acf2-4 (1.16 g, 1.98 mmol) obtained in step Acf2-4 and 3,4-dihydroxy-3-cyclobutene-1,2-dione (0.113 g, 0.988 mmol). And dissolved in a mixed solution of normal butanol (5 ml) and toluene (5 ml) under a nitrogen atmosphere. The mixture was stirred under reflux for 3 hours, and after completion of the reaction, the solvent was removed to obtain NIR dye (Acf2) (0.464 g, yield 37%) by silica gel chromatography (dichloromethane: hexane = 2: 1).

[Evaluation]
(Measurement of transmittance in dichloromethane)
The NIR dyes (A1-1) and (A2-1) obtained above, and the NIR dyes (Acf1) and (Acf2) were dissolved in dichloromethane, and the light absorption spectrum having a wavelength of 400 to 1000 nm was measured to measure the absorbance curve. The maximum absorption wavelength λ _{max (A) DCM} was obtained from the above. Furthermore, from the absorbance curve in which the dye concentration in dichloromethane was adjusted so that the light transmittance at the _{maximum absorption wavelength λ max (A) DCM was 10%, the transmittance T 418 (A) DCM at a} wavelength of 418 nm and the wavelength A transmittance T _{482 (A) DCM} at 482 nm was determined. The results are shown in Table 3. For the wavelengths of 418 nm and 482 nm, the absorption wavelengths next to the maximum absorption wavelengths of the NIR dye (A1-1) and the NIR dye (A2-1) in the measurement wavelength region were selected and compared.

(Solubility of resin in coating solution)
The solubility of the NIR dyes (A1-1) and (A2-1) obtained above and the NIR dyes (Acf1) and (Acf2) in the transparent resin coating solution was evaluated.

That is, a transparent resin (Neoprim (registered trademark) C3G30 (manufactured by Mitsubishi Gas Chemicals, Inc., trade name, polyimide resin)) was dissolved in a mixed solution (1: 1) of γ-butyrolactone and cyclohexanone at a concentration of 10% by mass. The above NIR dye was dissolved in the solution, and the solubility (% by mass) in the resin was evaluated. The results are shown in Table 3.

As is clear from the above evaluation results, the NIR dyes (A1-1) and (A2-1) and the NIR dyes (Acf1) and (Acf2) all have high light-shielding properties against near-infrared light. Further, from the above evaluation results, the NIR dye (Acf1) of Example 3 and the NIR dye (Acf2) of Example 4 which are comparative examples were carried out as compared with the case where either the visible light transmittance or the solubility in the coating solution was low. It can be seen that the NIR dye (A1-1) of Example 1 and the NIR dye (A2-1) of Example 2, which are examples, have high visible light transmittance and high solubility in the coating solution. Further, for the NIR dye (A1-1) and the NIR dye (A2-1), the coating solution obtained in the above test was applied onto a glass plate (D263; manufactured by SCHOTT, trade name), dried and filmed. An absorption layer having a thickness of 1 μm could be obtained.

[Example 5]
The optical filter having the configuration shown in FIG. 7 is manufactured by the following method.
As a transparent substrate, a glass substrate having a thickness of 0.21 mm made of CuO-containing borosilicate glass (manufactured by AGC Inc., trade name: NF-50GX) or a glass substrate having a thickness of 0.2 mm (D263; manufactured by SCHOTT, product). First name) is used.

As the reflective layer, a dielectric multilayer film formed as follows is used. The dielectric multilayer film is formed by alternately laminating a total of 42 layers _{of, for example, TiO 2} film and SiO ₂ film on one main surface of a glass substrate by a vapor deposition method. The structure of the reflective layer is _{simulated by using the number of laminated dielectric multilayer films, the film thickness of TiO 2} film, and the film thickness of SiO ₂ film as parameters, and light with a wavelength of 850 to 1100 nm in a spectral transmittance curve with an incident angle of 0 degrees. It is designed so that the average transmittance of is 0.03%.

Further, on the main surface opposite to the reflection layer of the glass substrate formed, one or more of the transparent resin and the NIR dye (A) are combined to form an absorption layer having a thickness of about 1.0 μm. Form. _{After that, seven layers of TiO 2} film and SiO ₂ film are alternately laminated on the surface of the absorption layer by a vapor deposition method to form an antireflection layer, and an optical filter (NIR filter) is obtained.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on May 29, 2018 (Japanese Patent Application No. 2018-102387), the contents of which are incorporated herein by reference.

The near-infrared absorbing dye of the present invention can realize excellent light-shielding property against near-infrared light and has high solubility in a solvent or resin, so that a homogeneous absorbing layer can be formed, and near-infrared light can be formed. It is applicable to optical filters that block light. The optical filter of the present invention can be applied to an imaging device.

10A, 10B, 10C, 10D, 10E, 10F, 10G ... Optical filter, 11, 11a, 11b ... Absorption layer, 12, 12a, 12b ... Reflective layer, 13 ... Transparent substrate, 14 ... Antireflection layer.

Claims (11)

A near-infrared absorbing dye composed of a compound represented by the formula (A1).

In formula (A1),
R ¹ and R ² may independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a substituent, and may contain an unsaturated bond or an oxygen atom between carbon atoms. It is an alkoxy group, an aryl group or an alaryl group. R ¹ and R ² may be linked to each other to form a 3- to 6-membered alicyclic or aromatic ring that may contain a heteroatom, in which case the hydrogen atom attached to the ring is substituted with a substituent. It may have been.
R ³ and R ⁴ may each independently have a substituent and may contain an unsaturated bond, an oxygen atom, an alicyclic or an aromatic ring between carbon atoms in a linear or branched chain form. It is an alkyl group of. The near-infrared absorbing dye according to claim ^1, wherein R 1 is a hydrogen atom. A near-infrared absorbing dye composed of a compound represented by the formula (A2).

In formula (A2),
R ⁵ and R ⁶ may independently have a hydrogen atom, a halogen atom, a hydroxyl group, or a substituent, and may contain an unsaturated bond or an oxygen atom between carbon atoms. It is an alkoxy group, an aryl group or an alaryl group.
R ⁷ and R ⁸ may each independently have a substituent and may contain an unsaturated bond, an oxygen atom, an alicyclic or an aromatic ring between carbon atoms in a linear or branched chain form. It is an alkyl group of. The near-infrared absorbing dye according to claim 3, wherein R ^{5 is a hydrogen atom.} An optical filter comprising an absorbing layer containing the near-infrared absorbing dye according to any one of claims 1 to 4 and a resin. The optical filter according to claim 5, further comprising a reflective layer including a dielectric multilayer film. The optical filter according to claim 5 or 6, further comprising a transparent substrate and having the absorption layer on the transparent substrate. The optical filter according to claim 7, wherein the transparent substrate is made of glass. The optical filter according to claim 8, wherein the glass is a near-infrared absorbing glass. The optical filter according to claim 7, wherein the transparent substrate is made of a resin. An image pickup apparatus comprising a solid-state image pickup device, an image pickup lens, and an optical filter according to any one of claims 5 to 10.

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