JPH0443947B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an infrared absorbing composition. More specifically, the present invention relates to an infrared absorbing composition useful for optical filters that absorbs far-red light or near-infrared light with a wavelength of 900 nm or more without substantially impairing the transmission of visible light. (Prior art) Various uses can be considered for compositions that selectively absorb far-red light or near-infrared light with a wavelength of 900 nm.
This has been strongly requested for some time, but until now we have not been able to obtain anything suitable. The main uses of conventional infrared absorbing compositions will be described below with reference to five examples. Safelight filter for infrared-sensitive photosensitive materials In recent years, many silver halide photosensitive materials (hereinafter referred to as ``sensitized materials'') that are sensitive to far-red or near-infrared light with a wavelength of 700 nm or more have been developed. It is coming. This includes black and white or color;
In addition, silver halide sensitive materials, including regular types, instant types, and heat-developable types, are equipped with infrared sensitivity to produce pseudo-color photographs for use in resource surveys, and diodes that emit light in the infrared region are used. There are some that can be used for exposure. A panchromatic safelight filter has conventionally been used for such infrared-sensitive materials. Control of plant growth It has long been known that light affects the so-called morphogenesis related to plant growth and differentiation, such as seed germination, stem elongation, leaf expansion, and flower bud and tuber formation. , has been studied as a photomorphogenetic effect. If a plastic film that selectively absorbs light with a wavelength of 700 nm or more could be obtained, for example, crops could be coated with a near-infrared absorbing film at a specific time to block light with a wavelength of 700 nm or more, thereby timing the heading period. It is expected to have the effect of slowing down or controlling growth (see Katsumi Inada, "Chemical Regulation of Plants", Vol. 6, No. 1 (1971)). Blocking heat rays Of the solar radiant energy, light in the near-infrared and infrared regions with a wavelength of 800 nm or more is absorbed by objects and converted into thermal energy. Moreover, most of the energy distribution is concentrated in the near-infrared wavelength range of 800 to 2000 nm. Therefore, films that selectively absorb near-infrared rays are extremely effective in blocking solar heat.
It is possible to suppress the rise in indoor temperature while allowing in sufficient visible light. This can be applied not only to horticultural greenhouses but also to windows of houses, offices, stores, automobiles, airplanes, etc. Conventionally, to block heat rays, a plastic film with a very thin metal layer deposited on its surface, or a glass with an inorganic compound such as FeO dispersed in it have been used. Infrared cutoff filters harmful to human eye tissues Infrared rays contained in sunlight or in the rays emitted during welding have a harmful effect on human eye tissues. One of the major uses of infrared cut filters is as eyeglasses that protect human eyes from such harmful infrared rays. For example, sunglasses, safety glasses for welders, etc. Infrared cut filter of semiconductor photodetector Currently, silicon photodiodes (hereinafter referred to as SPDs) are mainly used as photodetectors for photodetectors used in automatic exposure meters such as cameras. Figure 2 shows a graph of the relative luminous efficiency curve and the relative output value (spectral sensitivity) for each wavelength of the SPD. In order to use an SPD as a light meter, it is necessary to cut out light in the infrared region, which is invisible to the human eye, and to
It is necessary to make the SPD spectral sensitivity curve shown in the figure similar to the specific luminous efficiency curve. especially the wavelength
The output of the SPD is large for light in the range of 700 to 1100 nm, and light in this range is not perceptible to the eye, which can cause exposure meter malfunctions. For this reason, if it were possible to use an infrared absorbing plastic film that has little absorption in the visible region but absorbs the entire infrared region from 700 to 1100 nm, the light transmittance in the visible region would be large, and the output of the SPD would be large. It is clear that the performance of light meters can be significantly improved. Conventionally, this type of photodetection device has been put into practical use by attaching a glass infrared cut filter using an inorganic infrared absorber to the front of the SPD. (Problems to be Solved by the Invention) However, conventional general organic dye-based infrared absorbers have poor light resistance and heat resistance, and have hardly been practically satisfactory. Furthermore, the filter materials used for each of the above-mentioned applications also have the following drawbacks. First of all, the conventional panchromatic safe light filter for the above-mentioned purpose not only partially transmits green light, which has high visibility, but also transmits a large amount of infrared light, causing optical fog. However, the purpose of using this method as a safelight for sensitive materials could not be fully achieved. Furthermore, the plastic film with a vapor-deposited metal layer or the glass with dispersed FeO used for the above applications strongly absorbs not only infrared light but also light in the visible region, reducing the internal illuminance, making it particularly difficult to use for agricultural purposes. This was inappropriate because it would lead to an absolute shortage of sunlight. Furthermore, the glass infrared cut filters using inorganic infrared absorbers used in the above applications are relatively robust against heat and light, but have low light transmittance in the visible region, which makes SPD This was addressed by increasing the sensitivity. SPD
Increasing the sensitivity of the photodetector leads to an increase in leakage current, which causes malfunction of the photodetector and poses a major problem in terms of reliability. Furthermore, since the infrared cut filter is an inorganic material, it lacks flexibility from the viewpoint of manufacturing the photodetector, and it is difficult to improve the manufacturing process. Furthermore, inorganic infrared cut filters are expensive to manufacture and have the drawback of significantly increasing the cost of the photodetecting device. In this way, with conventional photodetection devices using inorganic cut filters, although their spectral sensitivities are close to the relative luminous efficiency curve, there are problems with lower operating performance as a photodetector, increased manufacturing costs, and improvements in the manufacturing process. It had significant drawbacks. Furthermore, near-infrared absorbing plastic films using complexes as infrared absorbers lack the solubility of the infrared absorbers in organic solvents, which has been a major drawback when producing thin plastic films. In other words, the above-mentioned applications are, for example, SPD.
For commercial filters, it is desirable to have an extremely thin film with high infrared absorption efficiency, but for this purpose a large amount of infrared absorber must be dispersed in the resin, and infrared absorbers with low solubility in organic solvents are It was not possible to satisfy that purpose. Furthermore, conventional near-infrared absorbing plastic films that use metal complexes as infrared absorbers have short maximum absorption wavelengths, making them unsuitable for applications such as light-receiving elements of semiconductor lasers, which have been increasingly used in recent years. . Therefore, the first object of the present invention is to provide an infrared absorbent having an absorption maximum on the long wavelength side, particularly at a wavelength of 900 nm or more. The second object is to provide a near-infrared absorber that has high solubility in organic solvents and good compatibility with film-forming binders. The present inventors have completed the present invention as a result of various studies to achieve the above object. (Means for solving the problem) The above objectives are achieved by the following general formula [] or []
The problem was solved by an infrared absorbing composition characterized by containing at least one complex selected from the following complexes. (In the formula, [Cat ₁ ] and [Cat ₂ ] represent cations necessary to neutralize the complex, and M ₁ and M ₂ represent nickel, copper, cobalt, palladium, or platinum.) The present invention will be explained in more detail. In the compounds represented by the general formulas [] and [], among the cations represented by [Cat ₁ ] or [Cat ₂ ], inorganic cations include alkali metals (for example, Li, Na, K, etc.), alkali Earth metals (Mg, Ca, Ba, etc.) or NH ₄ ⁺
can be given. Examples of the organic cation include quaternary ammonium ions and quaternary phosphonium ions. Among the above cations [Cat ₁ ] and [Cat ₂ ], the following general formulas (-a), (-b),
It is represented by (-c) or (-d). (In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ ,
R ⁹ , R ¹⁰ and R ¹¹ each have 1 to 20 carbon atoms
represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group having 6 to 14 carbon atoms, and Z ¹ and Z ² are bonded to the nitrogen or phosphorus atom in each formula to form a 5- or 6-membered ring. Represents a group of nonmetallic atoms that form . Examples of the substituted or unsubstituted alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, n-butyl group, iso-amyl group, n-dodecyl group, and n-octadecyl group. As an aryl group having 6 to 14 carbon atoms,
Examples include phenyl group, tolyl group, and α-naphthyl group. These alkyl or aryl groups include a cyano group, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms (for example, a methyl group, an ethyl group, an n-butyl group, an n-
octyl group, etc.), C6-C14 aryl group (e.g., phenyl group, tolyl group, α-naphthyl group, etc.), C2-C20 acyloxy group (e.g., acetoxy group, benzoyloxy group, or p-methoxybenzoyl group). (oxy group, etc.) C1-C6 alkoxy group (e.g., methoxy group, ethoxy group, propoxy group, butoxy group, etc.), aryloxy group (e.g., phenoxy group,
triloxy group) aralkyl group (such as benzyl group, phenethyl group or anisyl group),
Alkoxycarbonyl groups (e.g., methoxycarbonyl group, ethoxycarbonyl group, n-butoxycarbonyl group, etc.), aryloxycarbonyl groups (e.g., phenoxycarbonyl group, triloxycarbonyl group, etc.), acyl groups (e.g.,
acetyl group, benzoyl group, etc.), acylamino group (e.g., acetylamino group, benzoylamino group, etc.), carbamoyl group (e.g., N-
ethylcarbamoyl group, N-phenylcarbamoyl group, etc.), alkylsulfonylamino group (e.g., methylsulfonylamino group, phenylsulfonylamino group, etc.), sulfamoyl group (e.g., N-ethylsulfamoyl group, N-phenylsulfonylamino group, etc.) amoyl group, etc.), a sulfonyl group (eg, mesyl group, tosyl group, etc.). Further, Z ¹ and Z ² are a 5-membered ring or a 6-membered ring as described above.
Represents a group of nonmetallic atoms necessary to form a membered ring. Examples of these 5- or 6-membered rings include a pyridine ring, an imidazole ring, a pyrrole ring, a 2-pyrroline ring, a pyrrolidine ring, a piperidine ring, a pyrazole ring, a pyrazoline ring, and an imidazoline ring. Examples of the cation represented by the general formula (-b) include a dodecylpyridinium group, a hexadecylpyridinium group, and a dodecylimidazolium group. As the cation represented by the general formula (-c),
Examples include N-ethyl-N-hexadecylpiperidinium group and N-ethyl-N-dodecylpyrazolidinium group. The above general formulas (-a), (-b), (-c)
Among the cations represented by and (-d),
Particularly preferably used in the present invention is (-
a), (-b) and (-d). The types of the cations [Cat ₁ ] and [Cat ₂ ] affect the solubility of the compounds represented by the general formulas [] and [] in organic solvents. In general, when the substituent bonded to a quaternary heteroatom is an alkyl group, the longer the chain length, the higher the solubility, and this tendency is particularly marked in the case of tetraalkyl-substituted ammonium or phosphonium, and in the case of ammonium cations, the number of carbon atoms increases. Cations with a total of 17 or more carbon atoms, and in the case of phosphonium cations, cations with a total of 4 or more carbon atoms provide high solubility. Substituted alkyl and aralkyl groups also provide high solubility. The compounds represented by the general formulas [] and [] according to the present invention are preferably contained in a dispersed state in a binder as a composition, and are preferably highly compatible with the coating composition or the binder. In the compounds represented by the above general formulas [] and [], the preferred order of M ₁ or M ₂ is nickel, cobalt, copper, palladium, and platinum. In the case of nickel, the oxidation state is preferably trivalent rather than divalent, and a nickel complex with a divalent central metal does not exhibit strong infrared absorption. The metal complex of the general formula [] or [] has a three-dimensional structure with four-planar coordination. In addition, in the compound of the general formula [], whether the thioketone group is symmetrical or asymmetric with respect to the central metal is not uniquely determined, but in the present invention, for convenience, it is expressed as the general formula []. The compounds represented by the general formulas [] and [] can be synthesized as follows. The compound of general formula [] is disodium-1,3- obtained by reacting carbon disulfide and sodium.
First, dithiol-2-thione-4,5-dithiolate is converted into a zinc complex, and this is reacted with benzoyl chloride to form a bisbenzoylthio compound. After decomposing this with an alkali, a metal salt is reacted with the precipitated complex, which is then oxidized. In addition, the compound of the general formula [ ] is first obtained by reacting carbon disulfide with sodium, disodium-1,3-dithiol-2-thione-4,5-
Dithiolate is heated to about 130°C to form disodium-1,2-dithiol-3-thione-4,5-
Isomerize to dithiolate. This is made into a zinc complex, and this is reacted with benzoyl chloride to form a bisbenzoylthio compound. It is obtained by decomposing this with an alkali, then reacting with a metal salt, and oxidizing the precipitated complex. The 1,3-dithiol-2-thione-4,5-dithiolate anion, which is an intermediate for obtaining the compound of the general formula [] or [], is as described above.
In addition to the reduction method using Na, it can also be obtained by electrochemical reduction. Preferred examples of the compounds represented by the general formulas [] and [] are as follows, but it goes without saying that the present invention is not limited to these exemplified compounds. The infrared absorbing composition of the present invention is a composition in which a compound represented by the above general formula [] or [] is appropriately contained in a binder. There are no particular restrictions on the binder, and any binder can be used regardless of whether it is organic or inorganic as long as it exhibits infrared absorbing properties. Such binders include polymeric materials such as plastics, inorganic materials such as glass, and the like. Preferably, the binder used is a binder that forms a film with excellent transparency and mechanical properties. Examples of such film-forming binders include polyesters represented by polyethylene terephthalate, cellulose esters such as cellulose diacetate, cellulose triacetate, and cellulose acetate butyrate, polyolefins such as polyethylene and polypropylene, and polychloride. Hydrophilic materials such as vinyl, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl compounds such as polystyrene, acrylic addition polymers such as polymethyl methacrylate, polycarbonate consisting of polycarbonate, phenolic resin, urethane resin, or gelatin. Known film-forming binders such as binders can be mentioned. As a method of forming a film by adding and retaining the compound of the general formula [] or [] to the above-mentioned plastic material, there is a first method of blending it into the plastic at the time of film preparation. That is, if the compound of formula [] or [] is mixed with various additives into polymer powder or pellets, melted and extruded by a T-die method or inflation method, or made into a film by a calendar method, the compound can be obtained. A uniformly dispersed film is obtained. Further, when producing a film from a polymer solution by a casting method, the compound of the general formula [] or [] may be contained in the solution. Second, an infrared absorbing layer is formed by applying a polymer solution or dispersion containing the compound of the general formula [] or [] to the surface of various plastic films or glass plates manufactured by an appropriate method. There is a way to form it. As the binder polymer used in the coating solution, one is selected that can dissolve the compound of general formula [] or [] as well as possible and has excellent adhesiveness to the plastic film or glass plate serving as the support. Polymethyl methacrylate, cellulose acetate butyrate, polycarbonate, etc. are suitable for this purpose. The support film may be previously coated with a suitable primer to improve adhesion. The third method is to mix the compound of the general formula [] or [] with a polymerizable monomer in the light incident window frame of the element that is to block infrared rays, add a suitable polymerization initiator, and apply heat or light. Additionally, there is a method of polymerizing and forming a filter on the window frame using the resulting polymer. In this method, the entire device can also be embedded in a plastic made from polyaddition compositions such as ethylenically unsaturated polymerizable monomers or epoxy resins. The fourth method is a method in which the compound [] or [] according to the present invention is vapor-deposited on a suitable support. In this method, a suitable film-forming binder layer may also be provided as a protective layer at a position remote from the support. A method of using the near-infrared absorber according to the present invention in a color solid-state image sensor is described. After forming a striped or mosaic color separation filter layer having a plurality of predetermined spectral characteristics, a surface protective layer is provided on the filter layer. The near-infrared absorber of the present invention may be contained in the color separation filter layer, the absorber may be vapor-deposited, the near-infrared absorber of the present invention may be used in combination with a dye that absorbs visible light in the color separation filter layer, or the near-infrared absorber of the present invention may be used in combination with a color separation filter layer. It is also possible to incorporate this near-infrared absorber into a transparent intermediate layer or a smooth surface layer provided in the color separation filter. The optical filter obtained from the infrared absorbing composition of the present invention is particularly effective when used in combination with color separation filters such as those described in JP-A-57-58107, JP-A-59-9317 and JP-A-59-30509. It is. In the infrared absorbing composition of the present invention, two or more compounds represented by the general formula [] or [] may be used in combination. It can also be used in combination with known near-infrared absorbers of organic or metal complex type. In particular, when used in combination with absorbers with different absorption maximums, the absorption wavelength range can be expanded. In the infrared absorbing composition of the present invention, in order to further improve the light resistance, it is effective to add an ultraviolet absorber, such as substituted or unsubstituted benzoic acid esters such as resorcin monobenzoate, methyl salicylate, 2-oxy-3 -Cinnamate esters such as butyl methoxycinnamate, benzophenones such as 2,4-dioxybenzophenone, α,β-unsaturated ketones such as dibenzalacetone, 5,7
- Coumarins such as dioxycoumarin, 1,4-
Carbostyryls such as dimethyl-7-oxycarbostyryl, azoles such as 2-phenylbenzimidazole and 2-(2-hydroxyphenyl)benzotriazole, and the like are used. In addition, in the case of a film made by a coating method using the infrared absorbing composition of the present invention, a thin plastic film is pasted or coated on the surface of the coating layer for the purpose of protecting the coating layer and imparting droplet properties. You can also set it up. For example, by layering 0.05mm thick polyvinyl chloride film.
A laminated film is obtained by heat-pressing at 120-140°C. In the infrared absorbing composition of the present invention, the compound represented by the general formula [] or [] is contained in an amount of 0.1 to 50 parts by weight, preferably 0.5 parts by weight, per 100 parts of the binder.
Contain ~10 parts. The optical filter obtained from the infrared absorbing composition of the present invention only needs to have a low transmittance in the wavelength range that should be blocked functionally to the extent that it can achieve the intended purpose. 10% at the transmittance valley wavelength of 900 nm or more
Preferably 2.0% or less, particularly preferably 0.1%
It is important to adjust the amount added per binder and the thickness of the filter so that the transmittance is as follows. The practical thickness is 0.002 mm to 0.5 mm, but it is possible to design a filter with a thickness outside this range depending on the application. (Effects of the Invention) According to the present invention, a near-infrared absorbing composition having a maximum absorption wavelength of about 900 nm or more can be obtained. Further, an optical filter having excellent fastness to heat and light can be obtained, and a low-cost optical filter can be obtained. Furthermore, in the infrared absorbing composition of the present invention, the solubility in solvents can be adjusted by appropriately selecting and combining the cation species for the complex ion of the infrared absorber made of a metal complex, so that a wide variety of binders can be used. It has the advantage of The optical filter obtained from the infrared-absorbing composition of the present invention can be used as an infrared-absorbing material, as a safe light filter for infrared-sensitive materials, for controlling plant growth, blocking heat rays, and for human eye tissue. Harmful infrared cut filter, for infrared cut filter of semiconductor photodetector color solid-state image sensor,
In addition to being used as an infrared light cut filter in optoelectronic integrated circuits in which elements having both electrical and optical functions are incorporated on the same substrate, they can be used for a variety of other purposes. Furthermore, the composition according to the present invention can be applied to applications other than optical filters based on its infrared absorption properties. For example, when added to the inkjet printer ink described in JP-A No. 56-135568, reading efficiency by near-infrared light can be improved, and the reading efficiency of near-infrared light can be improved. It can also be applied to media. Furthermore, the composition of the present invention has the property of converting absorbed near-infrared light into heat, and can also be used as an infrared/heat exchange agent. Typical examples include: 1) Mixing caused by the heat generated by adding to a laser heat-sensitive recording material as described in JP-A-57-14095 or JP-A-57-14096 and irradiating it with an infrared laser. 2) For example, in JP-A-57-2009, the solubility changes due to the action of heat based on laser light.
3) When the compound of the present invention is included in a heat-drying or thermosetting composition as described in JP-A-56-143242, it causes a reaction. It can be promoted. The compound according to the present invention is also disclosed in Japanese Patent Application Laid-Open No.
As described in No. 214162, it can also be used as an electrophotographic photosensitive coating for an electrophotographic printer using a semiconductor laser as a light source. It can also be applied to coatings for optical discs that can be written and read using semiconductor lasers. Of course, the above description does not limit the uses of the compounds according to the present invention. (Examples) Next, the present invention will be described in more detail based on Examples. Reference Example 1 <Synthesis of Exemplary Compound (2)> (1-1) Bis(tetraethylammonium)
-bis(1,3-dithiol-2-thione-4,
Synthesis of 5-dithiolat) zinc complex. All reaction operations were performed under an argon atmosphere.
Cut 23g of sodium into small pieces and add 180ml of carbon disulfide.
After being dispersed in the solution, 200 ml of dimethylformamide was slowly added dropwise to the solution while stirring. Be careful not to overheat at this time. After dropping dimethylformamide, the mixture was carefully heated and refluxed for 24 hours. After the reaction was completed, unreacted sodium was filtered off. Then add 50ml of ethanol to the filtrate.
was added and stirred at room temperature for 2 hours. Carbon disulfide is distilled off from this solution under reduced pressure at room temperature. Then 300ml of water
was slowly added dropwise, and the resulting solution was filtered. Next, add 20g of zinc chloride to methanol in advance.
Prepare a solution by dissolving 53g of tetraethylammonium bromide in 250ml of water and adding 500ml of concentrated ammonia water to it. Add this to the above reaction solution and stir for 5 minutes (at room temperature), then add an aqueous solution of 53g of tetraethylammonium bromide dissolved in 250ml of water. Immediately, a red precipitate begins to separate out. This was filtered and air-dried to obtain a zinc complex. (1-2)4,5-bis(benzoylthio)-
Synthesis of 1,3-dithiol-2-thione. Add 22 g of the zinc complex obtained in (1-1) to 500 g of acetone.
Dissolve in ml and filter. While stirring the filtrate, add 150 ml of denzoyl chloride. A yellow precipitate immediately separates out. Filter, wash with water and air dry to obtain the title compound 16.
I got g. (1-3) Bis(tetrabutylphosphonium)
-bis(1,3-dithiol-2-thione-4,
Synthesis of 5-dithiolat)nickel() complex Bis(benzoylthio) compound obtained in (1-2)
Dissolve 9.2g in 50ml of methanol. Add 6.3 g of a 28% methanol solution of sodium methoxide to this and stir for 10 minutes. A solution of 2.4 g of nickel chloride (hexahydrate) dissolved in 50 ml of methanol is added to this solution, and the mixture is stirred at room temperature for 30 minutes. When a solution of 8.5 g of tetrabutylphosphonium bromide dissolved in 100 ml of methanol is added to this solution, a black precipitate is immediately deposited. Stir for an additional 20 minutes and filter. Washing with acetone, air drying, and recrystallization from acetone-isopropyl alcohol gave the title compound. Yield 3.8g (1-4) Tetrabutylphosphonium-bis(1,3-dithiol-2-thione-4,5-dithiolato)nickel() complex (exemplified compound (2))
synthesis of. 1 g of the nickel complex obtained in (1-3) was dissolved in 60 ml of acetone, 30 ml of acetic acid was added thereto, and the mixture was stirred for 3 hours and the solvent was distilled off. Black crystals were precipitated. These were recrystallized from acetone-methanol. In this way, the target exemplary compound (2) was obtained. Yield 0.4g
mp185℃ λmax: 1125nm, εmax: 2.51×10 ⁴
(in CH ₂ Cl ₂ ) Reference Example 2 <Synthesis of Exemplary Compound (10)> (1-1) Bis(tetraethylammonium)
-bis(1,2-dithiol-3-thione-4,
Synthesis of 5-dithiolat) zinc complex. All reaction operations were performed under an argon atmosphere.
Cut 23g of sodium into small pieces and add 180ml of carbon disulfide.
After being dispersed in the solution, 200 ml of dimethylformamide was slowly added dropwise to the solution while stirring. Be careful not to overheat at this time. After dropping dimethylformamide, the mixture was carefully heated and refluxed for 24 hours. After the reaction was completed, unreacted sodium was filtered off, and carbon disulfide was distilled off from the filtrate under reduced pressure at room temperature. The resulting solution was placed in an oil bath.
After stirring at 140°C for 2 hours, the mixture was allowed to cool to room temperature, 50 ml of ethanol was added thereto, stirred at room temperature for 2 hours, 300 ml of water was slowly added, and the resulting solution was filtered. Next, pre-prepared zinc chloride 20
g was dissolved in 500 ml of methanol, and 500 ml of concentrated aqueous ammonia was added thereto. The solution was added to the above reaction solution (at room temperature) and stirred for 5 minutes, and then an aqueous solution of 53 g of tetraethylammonium bromide dissolved in 250 ml of water was added. A red precipitate will immediately separate out. This was filtered and air-dried to obtain the title zinc complex. (1-2)4,5-bis(benzoylthio)-
Synthesis of 1,2-dithiol-3-thione. Add 18 g of the zinc complex obtained in (1-1) to 500 g of acetone.
Dissolve in ml and filter. While stirring the filtrate, add 150 ml of denzoyl chloride. A yellow precipitate immediately separates out. Filter, wash with water and air dry to obtain the title compound.
Obtained 12g. (1-3) Bis(tetrabutylammonium)
-bis(1,2-dithiol-3-thione-4,
Synthesis of 5-dithiolat)nickel() complex Bis(benzoylthio) compound obtained in (1-2)
Dissolve 9.2g in 50ml of methanol. To this was added 6.3 g of a 28% methanol solution of sodium methoxide, and the mixture was stirred for 10 minutes. Next, a solution of 2.4 g of nickel chloride (hexahydrate) dissolved in 50 ml of methanol was added to this solution, and after stirring at room temperature for 30 minutes, a solution of 7.5 g of tetrabutylammonium bromide dissolved in 100 ml of methanol was added to this solution. ,
A black precipitate was immediately deposited. The mixture was further stirred for 20 minutes, filtered, washed with acetone, and air-dried. Recrystallization from acetone-isopropyl alcohol gave the title compound. Yield 2.8g (1-4) Tetrabutylammonium-bis(1,2-dithiol-3-thione-4,5-dithiolato)nickel() complex (exemplified compound (10))
synthesis of. 1 g of the nickel complex obtained in (1-3) was dissolved in 60 ml of acetone, 30 ml of acetic acid was added thereto, the mixture was stirred for 3 hours, and the solvent was distilled off, resulting in the precipitation of black crystals. When this was recrystallized from acetone-methanol, the title exemplary compound (10) was obtained. Yield 0.3g mp207℃ λmax: 1138nm, εmax:
2.50×10 ⁴ (in CH ₂ Cl ₂ ) Example 1 An infrared absorbing composition was prepared using the exemplary compound (2) synthesized in Reference Example 1, and an optical filter was created. That is, each component is mixed with the composition shown below in parts by weight, stirred well, filtered, coated on a metal support by a casting method, formed into a film, and then peeled off to form the desired optical filter. Obtained. Several types of optical filters with dry film thicknesses varying between 0.02 and 0.3 mm were obtained. The optical density of the optical filter (25 microns thick) thus obtained is shown in FIG. Composition example TAC (cellulose triacetate) 170 parts TPP (triphenyl phosphate) 10 parts Methylene chloride 800 parts Methanol 160 parts Exemplary compound (2) 2 parts Example 2 Contains an ultraviolet absorber in the same manner as in Example 1 An optical filter with a thickness of 0.19mm was created. The composition of the casting composition is shown below. TAC (cellulose triacetate) 170 parts TPP (triphenylphosphite) 10 parts Methylene chloride 800 parts Methanol 160 parts Exemplary compound (2) 2 parts 2-(5-tert-butyl-2-hydroxyphenyl)benzotriazole 0.2 Part application example 1 Optical filter manufactured in Example 1 (thickness 0.05
mm) was attached to a silicon photodiode as a near-infrared cut filter, and the operating performance of the photodetector was greatly improved. Furthermore, the operational reliability showed no change at all even after a forced aging test at 50°C. When an ultraviolet absorber is used in combination with the metal complex according to the present invention, the light resistance of the filter is significantly improved. The light resistance of such a filter was determined by mixing the exemplified compound (2) and the ultraviolet absorber 2-(5-t-butyl-2-hydroxyphenyl)benzotriazole (compound (U)) in a weight ratio of 10:1. The table below shows the change over time in the optical density of the filter under light irradiation when the filters are used in combination at different ratios.

[Table] As can be seen from the above table, when the compound according to the present invention and an ultraviolet absorber were used in combination, the light fastness of the optical filter material could be dramatically improved.

[Brief explanation of drawings]

Figure 1 is a graph showing the optical density of an optical filter obtained from the infrared absorbing composition of the present invention, and Figure 2 is a graph showing the relative sensitivity of the human eye to the wavelength of light and
It is a graph showing the relative sensitivity of SPD. FIG. 1 is an optical density curve of an optical filter (thickness: 25 microns) using exemplified compound (2) obtained in Example 1.

Claims (1)

[Scope of Claims] 1. An infrared absorbing composition containing at least one compound selected from the following general formulas () and (). (In the formula, [Cat ₁ ] and [Cat ₂ ] represent cations necessary to neutralize the complex, and M ₁ and M ₂ represent nickel, copper, cobalt, palladium, or platinum.)