Diimonium compounds and their uses

Abstract

To provide diimonium compounds with high heat resistance, and resin compositions containing the same.SOLUTION: The invention provides diimonium compounds represented by the general formula (1) in the figure, and resin compositions and near-infrared cut filters obtained using the diimonium compounds. (In the formula (1), at least one of R1 to R8 is a methyl group.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to diimonium compounds having absorption in the infrared region and their applications, and more particularly to a near-infrared cut filter (optical filter) obtained by laminating a resin layer made of a diimonium compound with excellent heat resistance and a thermosetting resin composition containing the same. [Background technology]

[0002] Image sensors such as CCDs (Charge Coupled Devices) and CMOSs ​​(Complementary Metal Oxide Semiconductors) used in digital cameras and other devices have spectral sensitivity extending from the visible range to the near-infrared region around 1100 nm, while the human eye can perceive light with wavelengths around 400 to 700 nm. Therefore, because there is a significant difference in spectral sensitivity between image sensors and the human eye, it is necessary to equip the image sensor with a near-infrared cut filter in front of it to absorb near-infrared light and correct it to match the visual sensitivity of the human eye.

[0003] Glass filters made by adding CuO to phosphate-based glass are known as near-infrared cut filters used in image sensors. However, this glass with near-infrared absorption capability is very expensive. Furthermore, because it is glass, it has problems with processability, the degree of freedom in designing its optical properties is limited, and handling spherical surfaces is complicated. In addition, there is a limit to how thin the glass can be, which poses problems in terms of space allocation and weight reduction when incorporated into imaging optical systems.

[0004] Therefore, technology is being developed to produce near-infrared cut filters that can be made into thin films or molded into spherical shapes by coating the surface of an image sensor or filter substrate with a resin composition containing a near-infrared absorbing dye. Specifically, known near-infrared absorbing dyes include diimonium compound dyes, chromone-type squarylium compound dyes, phthalocyanine compound dyes, and naphthalene compound dyes.

[0005] It is known that the physical properties of diimonium compounds, such as heat resistance, humid heat resistance, solubility in solvents, and dispersibility in resin substrates, can be altered by changing the chemical structure of the end groups of the cation moiety or the anionic moiety. However, conventionally known diimonium compounds have insufficient heat resistance, and can undergo thermal degradation when mixed with resin compositions and processed and molded, thus posing a bottleneck to the thinning of near-infrared cut filters and, consequently, the further miniaturization and thinning of image sensors. Against this backdrop, there has been a strong demand in recent years for the development of diimonium compounds with a wide near-infrared absorption wavelength range and excellent heat resistance, as well as near-infrared cut filters using these compounds, and resin compositions for manufacturing them.

[0006] Patent Document 1 discloses a diimonium salt compound, which is a salt consisting of a diimonium cation and two tetrakis(pentafluorophenyl)boron anions, as a diimonium compound having near-infrared absorption ability. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2007-246464 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0008] The present invention aims to provide a diimonium compound having high heat resistance and a resin composition containing the same. It also aims to provide a near-infrared cut filter having a wide range of near-infrared absorption capacity and high heat resistance, which can be produced using the same. [Means for solving the problem]

[0009] As a result of intensive studies, the present inventors have found that a diimonium compound having a specific chemical structure described below has extremely excellent heat resistance, and by laminating a resin layer obtained from a thermosetting resin composition containing the diimonium compound, it contributes to the production of a near-infrared cut filter that solves the above problems, and completed the present invention.

[0010] That is, the present invention is as shown in the following (a) to (e).

[0011] (a): A diimonium compound represented by the following formula (1).

[0012]

Chemical formula

[0013] In formula (1), at least one of R1 to R8 is a methyl group.

[0014] (b): The diimonium compound according to (a), wherein R1 to R8 in formula (1) are methyl groups.

[0015] (c): A resin composition comprising the diimonium compound according to (a) or (b).

[0016] (d): The resin composition according to (c), further containing polycarbonate.

[0017] (e): A near-infrared cut filter comprising at least one resin layer containing the diimonium compound according to (a) or (b).

[0018] (f): The diimonium compound according to (a), having a melting point of 250 °C or higher.

Effects of the Invention

[0019] The diimonium compound of the present invention is excellent in heat resistance as a near-infrared absorbing dye, has a near-infrared absorbing ability that does not decrease over a long period of time, is excellent in dispersion and processability with a resin substrate, and has a wide range of near-infrared absorbing ability. In addition, since the compound itself does not contain heavy metals, there are no environmental problems.

[0020] Therefore, the resin composition containing the diimonium compound of the present invention as a near-infrared absorbing dye can be suitably used for an optical filter (near-infrared cut filter) used in an imaging device.

Embodiments for Carrying Out the Invention

[0021] The diimonium compound of the present invention is a compound represented by the following general formula (1).

[0022]

Chemical formula

[0023] In formula (1), at least one of R1 to R8 is a methyl group. Among these, in formula (1), those in which all of R1 to R8 are methyl groups are more preferable in terms of heat resistance and near-infrared absorbing ability.

[0024] The diimonium compound represented by formula (1) of the present invention can be obtained by a known method. That is, the following formula (2) obtained by reducing the product obtained by subjecting p-phenylenediamine and 1-chloro-4-nitrobenzene to an Ullmann reaction,

[0025]

Chemical formula

[0026] The compound represented by can be reacted in an organic solvent, preferably a water-soluble polar solvent such as DMF (dimethylformamide), DMI (dimethylimidazolinone), or NMP (N-methylpyrrolidone), at 30 to 160°C, preferably 50 to 140°C, with a halogenated compound corresponding to the desired R1 to R8 (for example, CH3Br when R1 to R8 are methyl groups) to obtain a compound of the following formula (3) (hereinafter referred to as the totally substituted product) in which all substituents (R1 to R8) are the same.

[0027] [ka]

[0028] The present invention provides a method for synthesizing the diimonium compound, which involves preparing the diimonium compound by a known method and then replacing its anionic portion with tetrakis(pentafluorophenyl)boric acid.

[0029] More specifically, for example, tetrakis(pentafluorophenyl)boric acid prepared according to the method described in International Publication WO2006 / 082945 is used as the anionic component. Silver is reacted with silver to produce silver tetrakis(pentafluorophenyl)borate, and the imonium compound represented by the above general formula (3) is reacted with an organic solvent such as N-methyl-2-pyrrolidone, dimethylformamide (hereinafter abbreviated as "DMF"), or acetonitrile at a temperature of 30 to 150°C. After filtering off the precipitated silver, a solvent such as water, ethyl acetate, or hexane is added, and the resulting precipitate is filtered to obtain the diimonium compound of the present invention.

[0030] The diimonium salt compound obtained in this manner is useful as a near-infrared absorbing dye, and a resin composition having near-infrared absorbing ability can be produced using this compound by known methods such as casting or melt extrusion.

[0031] The casting method involves dissolving or dispersing the diimonium compound (near-infrared absorbing dye) of the present invention in a solution of a polymer resin and a solvent, and then coating the solution onto a transparent film, panel, or glass substrate such as polyester or polycarbonate, and drying it to form a film.

[0032] The above-mentioned resins are transparent resins, such as acrylic resins, polyester resins, polycarbonate, urethane resins, cellulose resins, polyisocyanates, polyarylates, and epoxy resins.

[0033] Furthermore, the solvent is not particularly limited as long as it can dissolve the resin, but for example, organic solvents such as methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, tetrahydrofuran, 1,4-dioxane, or mixtures thereof can be used.

[0034] On the other hand, the melt extrusion method involves melting and kneading the diimonium compound of the present invention into a polymer resin, and then molding it into a panel shape by extrusion molding. Since the diimonium compound of the present invention has high heat resistance, it can be melted and kneaded at high temperatures.

[0035] The above-mentioned resins are transparent resins, such as acrylic resins, polyester resins, and polycarbonates.

[0036] The diimonium compound of the present invention can be used alone as a near-infrared absorbing dye, or it can be used with the addition of known dyes such as phthalocyanines or dithiol metal complexes to supplement its near-infrared blocking performance around a wavelength of 850 nm. Furthermore, ultraviolet absorbing dyes such as benzophenone or benzotriazole may be added to improve lightfastness. In addition, if necessary, known dyes that absorb in the visible light region may be added to adjust the color tone.

[0037] In this invention, the melting point of the diimonium compound is defined as the temperature (°C) relative to the maximum value of the melting peak of the diimonium compound when approximately 5 mg of the diimonium compound is weighed into an aluminum open pan using a thermogravimetric differential thermal analyzer (TG-DTA) (for example, an apparatus similar to the NEXTA STA300 (manufactured by Hitachi High-Tech Science Corporation)), and the diimonium compound is heated at a rate of 10°C / min.

[0038] The near-infrared cut filter (optical filter) of the present invention may be provided on a substrate or the substrate itself. The substrate is not particularly limited as long as it can be used for optical filters in general, but typically glass or resin substrates are used. The layer thickness is usually about 0.05 μm to 10 mm, but is appropriately determined according to the purpose, such as the near-infrared cut rate. Furthermore, the image sensor itself, such as a CCD or CMOS, can also be used as the substrate.

[0039] The content of the near-infrared absorbing dye used in the near-infrared cut filter of the present invention is also appropriately determined according to the desired near-infrared cut rate. Examples of resin substrates used include vinyl compounds such as polyethylene, polycycloalkanes, polycycloolefins, polystyrene, polyacrylic acid, polyacrylic acid esters, polyvinyl acetate, polyacrylonitrile, polyvinyl chloride, and polyvinyl fluoride, as well as addition polymers of these vinyl compounds, copolymers of vinyl compounds or fluorine compounds such as polymethacrylic acid, polymethacrylic acid esters, polyvinylidene chloride, polyvinylidene fluoride, polyvinylidene cyanide, vinylylidene fluoride / trifluoroethylene copolymer, vinylylidene fluoride / tetrafluoroethylene copolymer, and vinylylidene cyanide / vinyl acetate copolymer, fluorine-containing resins such as polytrifluoroethylene, polytetrafluoroethylene, and polyhexafluoropropylene, polyamides such as nylon 6 and nylon 66, polyimides, polyurethanes, polypeptides, polyesters such as polyethylene terephthalate, polycarbonates, polyethers such as polyoxymethylene, epoxy resins, polyvinyl alcohol, and polyvinyl butyral.

[0040] The method for producing the near-infrared cut filter (optical filter) of the present invention is not particularly limited, and known methods can be used. For example, 1) a method of producing a resin plate or film by forming a thermosetting resin composition consisting of a thermosetting resin, a curing agent, and a near-infrared absorbing dye, and then heating and curing it after molding; 2) a method of producing a coating containing a near-infrared absorbing dye, forming a resin composition, and coating a transparent resin plate, a transparent film, a transparent glass plate, or an image sensor; 3) a method of producing a composition containing a near-infrared absorbing dye and a resin (adhesive) (the thermosetting resin composition of the present invention) and producing a laminated resin plate, a laminated resin film, or a laminated glass plate.

[0041] Method 1) involves preparing a thermosetting resin composition consisting of a thermosetting resin, a curing agent, and a near-infrared absorbing dye, injecting it into a mold, and curing it by heating, or pouring it into a mold and heating it until it becomes a hard product. The processing temperature and film formation (resin sheet formation) conditions vary slightly depending on the composition used, but typically curing conditions of 100-200°C for 30 minutes to 5 hours are applied. The amount of near-infrared absorbing dye added varies depending on the thickness of the resin sheet or film to be produced, the absorption intensity, the visible light transmittance, etc., but typically about 0.01-30% by mass, preferably about 0.01-15% by mass, is used per 1 part by mass of the base resin.

[0042] Method 2) involves dissolving or dispersing a near-infrared absorbing dye in a binder resin to produce a coating, and a solvent can also be used during the coating process. Suitable solvents include halogen compounds, alcohol compounds, ketone compounds, ester compounds, aliphatic hydrocarbon compounds, aromatic hydrocarbon compounds, ether compounds, or mixtures thereof. The concentration of the near-infrared absorbing dye varies depending on the thickness, absorption intensity, and visible light transmittance of the coating to be produced, but is usually around 0.01 to 30% by mass per 1 part by mass of binder resin. The coating thus obtained can be coated onto a transparent resin plate, transparent film, transparent glass plate, or image sensor using a spin coater, bar coater, roll coater, gravure coater, offset coater, spray, etc., to obtain a near-infrared cut filter or an image sensor equipped with one.

[0043] Method 3) involves creating a near-infrared cut filter by using a thermosetting resin composition obtained by adding approximately 0.1 to 30% by mass of a near-infrared absorbing dye to a transparent adhesive known for use with resin compounds such as silicone-based, urethane-based, and acrylic-based adhesives, such as polyvinyl butyral adhesive or ethylene-vinyl acetate adhesive, for laminated glass, and bonding transparent resin plates together, resin plates and resin films, resin films and glass, and glass plates together. In addition, during kneading and mixing in each method, conventional additives used in resin molding, such as ultraviolet absorbers and plasticizers, may be added. [Examples]

[0044] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to these examples. In the examples, "mass%" will be abbreviated as "%", and "parts by weight" will be abbreviated as "parts".

[0045] Example 1 (1) 31.9 parts of silver tetrakis(pentafluorophenyl)borate and 11.8 parts of N,N,N',N'-tetrakis(p-dimethylaminophenyl)-p-phenylenediamine were added to 100 parts of DMF and reacted at 60°C for 3 hours. The resulting silver was filtered off. Next, 315 parts of water were added to the filtrate, and the resulting precipitate was filtered and dried to obtain 33.3 parts of N,N,N',N'-tetrakis(p-dimethylaminophenyl)-p-phenylenedimonium tetrakis(pentafluorophenyl)borate. This is a near-infrared absorbing dye with a maximum absorption wavelength (hereinafter abbreviated as "λmax") of 1046 nm and a molar extinction coefficient of 93000 [L·mol]. -1 ·cm -1 ] was. (2) The heat resistance of the obtained dyes was evaluated when heated at 190°C, 210°C, and 230°C. Specifically, the dye powder was dissolved in acetone, and a solution was prepared with a concentration of 10-20 mg / L. This solution was measured using a spectrophotometer, and the initial (before heating) molar extinction coefficient at a wavelength of 1000 nm was determined. After allowing the dye powder to stand for 60 minutes at each temperature, the molar extinction coefficient of the similarly prepared solution was measured, and the percentage of the molar extinction coefficient after heating relative to the initial (pre-heating) molar extinction coefficient was evaluated as the dye retention rate. The results are shown in Table 1.

[0046] Comparative Example 1 To 100 parts of DMF, 20.3 parts of silver tetrakis(pentafluorophenyl)borate and 11.8 parts of N,N,N',N'-tetrakis(p-diisobutylaminophenyl)-p-phenylenediamine were added and reacted at 60°C for 3 hours. The resulting silver was filtered off. Next, 200 parts of water were added to the filtrate, and the resulting precipitate was filtered and dried to obtain 24.8 parts of N,N,N',N'-tetrakis(p-diisobutylaminophenyl)-p-phenylenedimonium tetrakis(pentafluorophenyl)borate. This is a near-infrared absorbing dye with a maximum absorption wavelength (hereinafter abbreviated as "λmax") of 1077 nm and a molar extinction coefficient of 105,000 [L·mol]. -1 ·cm -1 ] was. The obtained dyes were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0047] Comparative Example 2 157.5 parts of DMF were mixed with 15.7 parts of silver bis(trifluoromethanesulfone)imate and 11.8 parts of N,N,N',N'-tetrakis(p-dimethylaminophenyl)-p-phenylenedimonium, and the mixture was reacted at 60°C for 3 hours. The resulting silver was filtered off. Next, 315 parts of water were added to the filtrate, and the resulting precipitate was filtered and dried to obtain 19.2 parts of N,N,N',N'-tetrakis(p-dimethylaminophenyl)-p-phenylenedimonium bis(trifluoromethanesulfone)imate. This is a near-infrared absorbing dye with a maximum absorption wavelength (hereinafter abbreviated as "λmax") of 1046 nm and a molar extinction coefficient of 93000 [L·mol]. -1 ·cm -1 ] was. The obtained dyes were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0048] Comparative Example 3 To 100 parts of DMF, 10 parts of silver bis(trifluoromethanesulfone)imate and 11.8 parts of N,N,N',N'-tetrakis(p-diisobutylaminophenyl)-p-phenylenediamine were added and reacted at 60°C for 3 hours. The resulting silver was filtered off. Next, 200 parts of water were added to the filtrate, and the resulting precipitate was filtered and dried to obtain 15.7 parts of N,N,N',N'-tetrakis(p-diisobutylaminophenyl)-p-phenylenedimonium bis(trifluoromethanesulfone)imate. This is a near-infrared absorbing dye with a maximum absorption wavelength (hereinafter abbreviated as "λmax") of 1077 nm and a molar extinction coefficient of 105,000 [L·mol]. -1 ·cm -1 ] was. The obtained dyes were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0049] Comparative Example 4 To 100 parts of DMF, 20.3 parts of silver tetrakis(pentafluorophenyl)borate and 11.8 parts of N,N,N’,N’-tetrakis(p-dibutylaminophenyl)-p-phenylenediamine were added, and the mixture was reacted at 60 °C for 3 hours. The generated silver was filtered off. Subsequently, 200 parts of water was added to the filtrate, and the generated precipitate was filtered and then dried to obtain 24.8 parts of N,N,N’,N’-tetrakis(p-dibutylaminophenyl)-p-phenylenediimmonium tetrakis(pentafluorophenyl)borate. This is a near-infrared absorbing dye, with a maximum absorption wavelength (hereinafter abbreviated as "λmax") of 1072 nm and a molar absorption coefficient of 102000 [L·mol -1 ·cm -1 . The heat resistance of the obtained dye was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0050] Comparative Example 5 To 100 parts of DMF, 10 parts of silver bis(trifluoromethanesulfonyl)imide and 11.8 parts of N,N,N’,N’-tetrakis(p-dibutylaminophenyl)-p-phenylenediamine were added, and the mixture was reacted at 60 °C for 3 hours. The generated silver was filtered off. Subsequently, 200 parts of water was added to the filtrate, and the generated precipitate was filtered and then dried to obtain 15.7 parts of N,N,N’,N’-tetrakis(p-dibutylaminophenyl)-p-phenylenediimmonium bis(trifluoromethanesulfonyl)imide. This is a near-infrared absorbing dye, with a maximum absorption wavelength (hereinafter abbreviated as "λmax") of 1072 nm and a molar absorption coefficient of 102000 [L·mol -1 [[ID=…]]·cm -1 . The heat resistance of the obtained dye was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0051] Comparative Example 6 132 parts of DMF were mixed with 26.8 parts of silver tetrakis(pentafluorophenyl)borate and 11.8 parts of N,N,N',N'-tetrakis(p-diethylaminophenyl)-p-phenylenediamine. The mixture was reacted at 60°C for 3 hours, and the resulting silver was filtered off. Next, 264 parts of water were added to the filtrate, and the resulting precipitate was filtered and dried to obtain 29.6 parts of N,N,N',N'-tetrakis(p-diethylaminophenyl)-p-phenylenedimonium tetrakis(pentafluorophenyl)borate. This is a near-infrared absorbing dye with a maximum absorption wavelength (hereinafter abbreviated as "λmax") of 1057 nm and a molar extinction coefficient of 99700 [L·mol]. -1 ·cm -1 ] was. The heat resistance of the obtained dyes was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0052] Comparative Example 7 13.2 parts silver bis(trifluoromethanesulfone)imate and 11.8 parts N,N,N',N'-tetrakis(p-diethylaminophenyl)-p-phenylenedimonium were added to 132 parts DMF and reacted at 60°C for 3 hours. The resulting silver was filtered off. Next, 264 parts water was added to the filtrate, and the resulting precipitate was filtered and dried to obtain 17.7 parts N,N,N',N'-tetrakis(p-diethylaminophenyl)-p-phenylenedimonium bis(trifluoromethanesulfone)imate. This is a near-infrared absorbing dye with a maximum absorption wavelength (hereinafter abbreviated as "λmax") of 1057 nm and a molar extinction coefficient of 99700 [L·mol]. -1 ·cm -1 ] was. The heat resistance of the obtained dyes was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0053] [Table 1]

[0054] In Table 1, "End group of cation" indicates that R1 to R8 in formula (1) are the corresponding end groups, "TEPB" indicates the tetrakis(pentafluorophenyl)boron anion, and "TFSI" indicates the bis(trifluoromethanesulfonyl)imide anion.

[0055] As described above, the diimonium compounds of the embodiments of the present invention have high heat resistance.

[0056] Example 2 0.5 parts of the diimonium compound obtained in Example 1 and 99.5 parts of polycarbonate resin (Panlite L-1250Y, manufactured by Teijin Limited) were fed into the feed port of a twin-screw kneader (Laboplastmill, manufactured by Toyo Seiki Seisakusho Co., Ltd.) and melt-mixed at a temperature of 260°C to obtain a resin composition. The obtained resin composition was pressed using a hot press at a temperature of 230°C to obtain an infrared cut filter with a thickness of 0.25 mm.

[0057] Comparative Example 8 An infrared cut filter was obtained in the same manner as in Example 2, except that the diimonium compound of Example 1 was replaced with that of Comparative Example 1.

[0058] Comparative Example 9 An infrared cut filter was obtained in the same manner as in Example 2, except that the diimonium compound of Example 1 was replaced with that of Comparative Example 2.

[0059] Comparative Example 10 An infrared cut filter was obtained in the same manner as in Example 2, except that the diimonium compound of Example 1 was replaced with that of Comparative Example 3.

[0060] Comparative Example 11 An infrared cut filter was obtained in the same manner as in Example 2, except that the diimonium compound of Example 1 was replaced with that of Comparative Example 4.

[0061] Comparative Example 12 An infrared cut filter was obtained in the same manner as in Example 2, except that the diimonium compound of Example 1 was replaced with that of Comparative Example 5.

[0062] Comparative Example 13 An infrared cut filter was obtained in the same manner as in Example 2, except that the diimonium compound of Example 1 was replaced with that of Comparative Example 6.

[0063] Comparative Example 14 An infrared cut filter was obtained in the same manner as in Example 2, except that the diimonium compound of Example 1 was replaced with that of Comparative Example 7.

[0064] Table 2 shows the results of measuring the transmittance of the obtained infrared cut filter at wavelengths of 1000 nm and 500 nm using a spectrophotometer.

[0065] [Table 2]

[0066] In Table 2, "cationic terminal group" indicates that R1 to R8 in formula (1) are the corresponding terminal groups, "TEPB" indicates the tetrakis(pentafluorophenyl)boron anion, and "TFSI" indicates the bis(trifluoromethanesulfonyl)imide anion.

[0067] As described above, the near-infrared cut filter of the embodiment of the present invention has a wide range of near-infrared absorption capacity and high heat resistance. [Industrial applicability]

[0068] The resin composition containing the diimonium compound of the present invention, which has near-infrared absorbing ability, can be used in a variety of applications, and is suitably used, for example, in near-infrared blocking filters for PDPs, near-infrared blocking filters for automotive glass or building material glass. Furthermore, the near-infrared absorbing dye of the present invention can also be used as a dye or quencher for optical recording media such as CD-R and DVD-R, which is a conventional application.

[0069] The near-infrared cut filter of the present invention can be used not only for image sensors and display front panels, but also for filter films that need to cut near-infrared rays, such as heat insulating films, optical products, and sunglasses.

Claims

1. A diimonium compound represented by the following formula (1). 【Chemistry 1】 (In formula (1), R １ ~R ８ (This is a methyl group.)

2. A resin composition characterized by containing the diimonium compound described in claim 1.

3. The resin composition according to claim 2, further containing polycarbonate.

4. A near-infrared cut filter characterized by comprising at least a resin layer containing the diimonium compound described in claim 1.

5. The diimonium compound according to claim 1, wherein the melting point is 250°C or higher.

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