JP2002303720A - Near ir ray absorbing filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a near IR ray absorbing filter which has intense and wide absorption in the near IR region, high transmittance for light in the visible ray region, no intense absorption at a specified wavelength in the visible ray region and good processability and productivity and which is stable in the performance for a long time even at high temperature and high humidity. SOLUTION: The near IR ray absorbing filter is obtained by applying and drying a coating liquid containing a composition prepared by dispersing near IR ray absorption dyes in a binder resin on a substrate. The filter shows <=25% maximum in the change rate V (%) of the transmittance expressed by formula (1): V=100×|T0( WL) -T1( WL) |/T0( WL) . In the formula, T0( WL) is the transmittance at the wavelength WL, T1( WL) is the transmittance at the wavelength WL after the filter is stored at 60 deg.C and 95% humidity for 500 hours, and WL is the wavelength from 420 nm to 1,100 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical filter, and more particularly, to a near-infrared ray which has a high transmittance in a visible light region, is stable in performance even when left under high temperature and high humidity for a long time, and has a high efficiency. It relates to an optical filter.

[0002]

2. Description of the Related Art Conventionally, the following ones have been used as near-infrared absorption filters such as a heat ray absorption filter and a filter for correcting the visibility of a video camera. Filters containing phosphoric acid-based glass and metal ions such as copper and iron (JP-A-60-235740, JP-A-62-153144). Interference filters that transmit specific wavelengths by laminating layers having different refractive indices on a substrate and causing transmitted light to interfere (Japanese Patent Laid-Open Nos. 55-21091 and 59-18474).
No. 5 publication).

Acrylic resin filters containing copper ions in the copolymer (JP-A-6-324213).

A filter having a structure in which a dye is dispersed in a binder resin (Japanese Patent Application Laid-Open No. 57-21458, Japanese Patent Application Laid-Open No.
7-198413, JP-A-60-43605 and the like.

[0005]

The above-mentioned near-infrared absorbing filters which have been used conventionally have the following problems.

[0006] The above-mentioned filter has a steep absorption in the near infrared region, and the near infrared blocking ratio is very good. However, since it is glass, there is a problem in workability, and the degree of freedom in designing optical characteristics is narrow. In addition, a part of red in the visible region is also largely absorbed, and the transmitted color looks blue. In display applications, color balance is emphasized, and in such a case, it is difficult to use.

In the case of the above-mentioned filter, the optical characteristics can be freely designed, and it is possible to manufacture a filter substantially equivalent to the designed one. However, for this purpose, it is necessary to increase the number of layers having a difference in refractive index to a very large number, resulting in a drawback such as an increase in manufacturing cost. Further, when a large area is required, a high-accuracy film thickness uniformity is required over the entire area, and thus there is a problem in productivity.

[0008] In the case of the above-mentioned filter, workability, which is a disadvantage of the above-mentioned filter, is improved. However, like the above filters, the degree of freedom in optical design is low.
Also, some of the red color in the visible region is also greatly absorbed,
The problem that looks blue is the same as the above filter. Furthermore, since the absorption of copper ions is small and the amount of copper ions that can be contained in the acrylic resin is limited, there is a problem that the acrylic resin must be thick.

The above filter has good workability and productivity, can be manufactured at low cost, and has a relatively large degree of freedom in optical design. As near-infrared absorbing dyes, phthalocyanine-based dyes,
Many dyes such as thiol metal complex type, azo compound, polymethine type, diphenylmethane type, triphenylmethane type, quinone type, and diimonium salt type are used. However, each of them alone has insufficient absorption in the near infrared region or has a narrow absorption region, resulting in an insufficient cutoff ratio in the near infrared region. For this reason, it is common to use a mixture of multiple dyes.However, if a filter containing multiple dyes is left under high temperature and high humidity for a long time, the dyes will be denatured and the performance will deteriorate. There are many. Further, in the case of a dye that does not denature even when left under high temperature and high humidity for a long time, there is a problem that the transmittance in the visible light region is small, and the visible light region has a large specific absorption and is colored.

In recent years, a plasma display has been attracting attention as a thin large-screen display. However, there is a problem that unnecessary near-infrared rays emitted from the plasma display may cause malfunction of electronic equipment using a near-infrared remote control. Therefore, it is necessary to provide a material that absorbs near infrared rays on the front surface of the plasma display. However, conventionally used materials cannot be said to provide satisfactory materials for the reasons described above.

An object of the present invention is to have a large and wide absorption in the near-infrared region, a high light transmittance in the visible region,
Another object of the present invention is to provide a near-infrared absorption filter which does not have large absorption at a specific wavelength in the visible region, has good processability and productivity, and is stable in performance for a long time even under high temperature or high humidity.

[0012]

The near-infrared absorbing filter of the present invention which has achieved the above object is as follows.

The first invention is a near-infrared absorbing filter formed by laminating a coat layer comprising a composition in which a near-infrared absorbing dye is dispersed in a binder resin on a substrate,
A near-infrared absorption filter characterized in that the maximum value of the rate of change of transmittance V (%) represented by the following formula (1) is 25% or less.

V = 100 × | T _{0 (WL)} −T _{1 (WL)} | / T _{0 (WL)} (1) where T _{0 (WL)} : transmittance at wavelength WL, T _{1 (WL)} : transmittance at a wavelength WL after storage at a temperature of 60 ° C. and a humidity of 95% for 500 hours, where WL represents each wavelength from 420 nm to 1100 nm.

A second invention is the near-infrared absorbing filter according to the first invention, wherein the binder resin has a glass transition temperature of 85 to 140 ° C.

The third invention is the near-infrared absorbing filter according to the first or second invention, wherein the near-infrared absorbing dye contains a diimmonium salt compound represented by the following formula (2).

[0017]

Embedded image

[0018] (wherein, R ₁ to R ₈ is a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, an aralkyl group, an alkynyl group, even each identical or different may .R ₉ also be ~ R ₁₂ represents a hydrogen atom, a halogen atom, an amino group, a cyano group, a nitro group, a carboxyl group, an alkyl group, or an alkoxy group, and may be the same or different, and may be substituted with R _{1 to} R ₁₂ . A compound capable of bonding to a group may have a substituent. X ⁻ represents an anion.) A fourth invention is a method of using a fluorinated phthalocyanine compound and / or a dithiol metal complex compound as the near-infrared absorbing dye. It is a near-infrared absorption filter according to any one of the first to third inventions.

According to a fifth aspect of the present invention, the dithiol metal complex compound is a compound represented by the following formula (3):
The near-infrared absorbing filter according to the invention.

[0020]

Embedded image

(R _{13 to} R ₁₆ are a hydrogen atom, a halogen atom,
Represents an alkyl group, an alkoxyl group, an aryl group, an aralkyl group, or an amino group, which may be the same or different. The sixth invention is the near-infrared absorbing filter according to any one of the first to fifth inventions, wherein the substrate is a transparent substrate.

A seventh invention is the near-infrared absorbing filter according to the sixth invention, wherein the transparent substrate is a polyester film.

The eighth invention is further characterized in that one or both sides have:
The near-infrared absorbing filter according to any one of the first to seventh inventions, wherein a peelable protective film is laminated.

The ninth invention is further characterized in that one or both sides have
The near-infrared absorbing filter according to any one of the first to eighth inventions, wherein a release film is laminated via an adhesive layer.

A tenth aspect of the present invention is the near-infrared absorbing filter according to any one of the first to ninth aspects, wherein a metal mesh conductive layer having an aperture ratio of 50% or more is further laminated on one or both sides. is there.

According to an eleventh invention, the transparent conductive layer is further laminated on one or both surfaces.
The near-infrared absorption filter according to any one of the inventions.

The twelfth invention is the near-infrared absorbing filter according to any one of the first to eleventh inventions, wherein an antireflection layer is further laminated on the outermost layer.

A thirteenth invention is the near-infrared absorbing filter according to any one of the first to twelfth inventions, wherein an antiglare treatment layer is further laminated on the outermost layer.

A fourteenth invention is the near-infrared absorption filter according to any one of the first to thirteenth inventions, which is installed on the front surface of the plasma display.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The near-infrared filter of the present invention prepares a coating solution in which a near-infrared absorbing dye and a binder resin are uniformly dispersed in a solvent, coats the coating solution on a substrate, evaporates the solvent by drying, and forms a binder resin film. It is produced.

The near-infrared absorbing filter of the present invention has stable spectral characteristics even when left under high temperature and high humidity for a long time. Specifically, in an environment of a temperature of 60 ° C. and a humidity of 95%, 5
Before and after storage for 00 hours, the wavelength from 420 nm to 1100
The maximum value of the change rate V (%) of the transmittance (%) at each wavelength of nm is 25% or less. The rate of change of transmittance V (%) at each wavelength is represented by the above equation (1).

In the near-infrared absorbing filter of the present invention, the amount of the residual solvent in the coating layer laminated on the substrate has a great influence on the stability of the near-infrared dye. That is,
In the present invention, the amount of the residual solvent in the coat layer is set to 5.
When the content is 0% by mass or less, the stability of the near-infrared absorbing dye under high temperature and high humidity is dramatically improved.

In general, when performing coating, it is necessary to dry the coating so as not to cause blocking. In this case, the concentration of the residual solvent is about 7.0% by mass or less. When the amount of the residual solvent is more than 5.0% by mass and not more than 7.0% by mass, it is apparently dry and no blocking occurs. However, when it is left for a long time under high temperature and high humidity, the apparent appearance of the binder resin is obtained. , The near infrared absorbing dye is denatured due to the interaction between the residual solvent and the dye, the interaction between the binder resin and the dye, the interaction between different dyes, and the like. As a result, absorption in the near-infrared region decreases, and it becomes impossible to sufficiently block near-infrared rays. Further, light transmittance in the visible region is reduced, or absorption of a specific wavelength appears in the visible region, and the filter is colored.

In the present invention, the amount of the residual solvent in the coating layer is particularly preferably 0.05 to 3.0% by mass.
When the amount of the residual solvent is less than 0.05% by mass, the denaturation of the near-infrared absorbing dye when left under high temperature and high humidity for a long time is small. The infrared absorbing dye is easily denatured.

In order to reduce the amount of the residual solvent in the coating layer to 5.0% by mass or less, it is necessary to simultaneously satisfy the drying conditions of the following formulas (4) to (6). The following equation (4)
The unit of the factors used in (6) is wind speed m / sec, hot air temperature is ° C., drying time is minute, and coat thickness is μm. Wind speed × (hot air temperature−20) × drying time / coat thickness> 48 (4) Hot air temperature: ≧ 80 ° C. (5) Drying time: ≦ 60 minutes (6).

The near-infrared absorbing dye used in the present invention preferably contains a diimonium salt compound represented by the above formula (2).

The diimmonium salt compound represented by the above formula (2) has a large absorption in the near infrared region and a wide absorption range.
The transmittance in the visible region is also high. However, the diimmonium salt-based compound is denatured under high temperature or high humidity, the absorption in the near-infrared region is reduced, the transmittance in a part of the visible region is reduced, and the compound is colored. This phenomenon is further accelerated when other dyes are mixed. However, in the case of the diimmonium salt compound represented by the formula (2), if the amount of the residual solvent in the composition in which the dye is dispersed in the binder resin is adjusted to 5.0% by mass or less, the heat resistance and the moisture resistance are particularly improved. We have found that significant. Further, by setting the amount of the residual solvent to 3.0% by mass or less, improvement in heat resistance and moisture resistance is further promoted.

Specific examples of R _{1 to} R _{8 in} the above formula (2) include, as an alkyl group, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an iso-butyl group.
Butyl group, ter-butyl group, n-amyl group, n-hexyl group, n-octyl group, 2-hydroxyethyl group, 2
-A cyanoethyl group, a 3-hydroxypropyl group, a 3-cyanopropyl group, a methoxyethyl group, an ethoxyethyl group, a butoxyethyl group, and the like. As the aryl group, a phenyl group, a fluorophenyl group, a chlorophenyl group, a tolyl group, a diethylaminophenyl, A naphthyl group and the like; an alkenyl group such as a vinyl group, a propenyl group, a butenyl group and a pentenyl group; and an aralkyl group such as a benzyl group, a p-fluorobenzyl group, a p-chlorophenyl group, a phenylpropyl group and a naphthylethyl group. And the like. Further, as R _{9 to} R ₁₂ , hydrogen, fluorine,
Chlorine, bromine, diethylamino, dimethylamino, cyano, nitro, methyl, ethyl, propyl,
Examples include a trifluoromethyl group, a methoxy group, an ethoxy group, and a propoxy group. X ⁻ is, for example, a fluorine ion, chlorine ion, bromine ion, iodine ion, perchlorate ion, hexafluoroantimonate ion, hexafluorophosphate ion, or tetrafluoroborate ion. However, the present invention is not limited to those described above. Some of these are available as commercial products, for example, Nippon Kayaku Kayasorb IRG-
022 or the like can be suitably used.

The near-infrared absorbing filter of the present invention comprises, in addition to the diimonium salt compound represented by the above formula (2),
Other near-infrared absorbing dyes can be added for the purpose of expanding the near-infrared absorption region and adjusting the color tone. As the dye to be added, a fluorinated phthalocyanine compound and a dithiol metal complex compound are particularly preferable. Any one or both of them can be added. Examples of the fluorine-containing phthalocyanine-based compound, for example, Nippon Shokubai Co., Ltd.Excolor IR-1, IR-2, IR-3, IR-4, TXEX-805K, TXEX-
809K, TXEX-810K, TXEX-811K, TXEX-812K and the like can be suitably used.

As the dithiol metal complex compound, a compound represented by the above formula (3) is preferably used.

Specific examples of R _{13 to} R _{16 in} the above formula (3) include fluorine, chlorine and bromine as halogen atoms, and methyl, ethyl, n-propyl and iso-propyl as alkyl groups. Group, n-butyl group, iso-butyl group, t-butyl group, n-amyl group, n-hexyl group,
n-octyl group, 2-hydroxyethyl group, 2-cyanoethyl group, 3-hydroxypropyl group, 3-cyanopropyl group, methoxyethyl group, ethoxyethyl group, butoxyethyl group, etc.
An ethoxy group, a propoxy group, a butoxy group, and the like, an aryl group includes a phenyl group, a fluorophenyl group, a chlorophenyl group, a tolyl group, a diethylaminophenyl, a naphthyl group, and the like, and an aralkyl group includes a benzyl group, p
-Fluorobenzyl group, p-chlorophenyl group, phenylpropyl group, naphthylethyl group and the like, and the amino group include dimethylamino group, diethylamino group, dipropylamino group and dibutylamino group. As commercial products, SIR-128 and SIR manufactured by Mitsui Chemicals, Inc.
-130, SIR-132, SIR-159 and the like can also be suitably used.

The above-mentioned near-infrared absorbing dye is an example, and the present invention is not limited thereto.

The near-infrared absorbing filter of the present invention is produced by coating on a base material. The base material has a high transparency as well as a plastic film in terms of cost and ease of handling. preferable. Specifically, polyester-based, acrylic-based, cellulose-based, polyethylene-based, polypropylene-based, polyolefin-based, polyvinyl chloride-based, polycarbonate, phenol-based, urethane-based resin films, and the like, but polyester-based resins are particularly preferred. preferable.

The binder resin used in the present invention is not particularly limited as long as it can uniformly disperse the near-infrared absorbing dye used in the present invention. Examples of the binder resin include polyester, acrylic, polyamide, polyurethane, polyolefin, and polycarbonate resins. Resin can be suitably used.

Further, the glass transition temperature of the binder resin is preferably higher than the guaranteed use temperature of the equipment to be used. When the glass transition temperature is lower than the device operating temperature, the pigments dispersed in the binder resin react with each other or the binder resin absorbs moisture or the like in the outside air, and the pigment and the binder resin are greatly deteriorated.

In the present invention, the glass transition temperature of the resin is not particularly limited as long as it is not lower than the operating temperature of a device using a near-infrared absorbing filter.
Particularly preferred is 40 ° C. or lower. When the glass transition temperature is lower than 85 ° C., an interaction between the dye and the resin, an interaction between the dyes, and the like occur, and the dye is denatured. When the glass transition temperature exceeds 140 ° C., the resin must be dissolved in a solvent and heated to a high temperature in order to dry sufficiently when coated on a transparent substrate. When used, the pigment is deteriorated. Furthermore, when dried at a low temperature, the drying time is long and the productivity is poor, so that an inexpensive near-infrared absorbing filter cannot be produced. In addition, sufficient drying may not be possible, and the solvent remains in the coating film, and as described above, the apparent glass transition temperature of the binder resin is lowered, which also causes the pigment to be denatured.

In the present invention, the solvent used for the coating solution at the time of coating may be any solvent as long as it can uniformly disperse the near-infrared absorbing dye and the binder resin used in the present invention. For example, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, methanol, ethanol, isopropyl alcohol, ethyl cellosolve, butyl cellosolve, benzene, toluene, xylene, tetrahydrofuran, n-hexane, n-heptane, methylene chloride, chlorophorom, N , N-dimethylformamide, water and the like, but are not limited thereto.

In the present invention, for the purpose of blocking harmful electromagnetic waves emitted from the display, the same surface as the infrared absorbing layer,
Alternatively, a conductive layer may be provided on the opposite surface. As the conductive layer, either a metal mesh or a conductive thin film may be used. However, when a metal mesh is used, it is necessary that the metal mesh conductive layer has an aperture ratio of 50% or more. If the aperture ratio of the metal mesh is low, the electromagnetic wave shielding property is good, but there is a problem that the light transmittance is reduced. Therefore, in order to obtain good light transmittance, the aperture ratio needs to be 50% or more. As the metal mesh used in the present invention, a metal foil having a high electrical conductivity is subjected to an etching treatment to form a mesh, a woven mesh using metal fibers, a metal plated on the surface of a polymer fiber, or the like. May be used.

The metal used for such an electromagnetic wave absorbing layer is
Any metal may be used as long as it has high electric conductivity and good stability, and is not particularly limited, but copper, nickel, tungsten, and the like are preferable from the viewpoint of workability, cost, and the like.

When a conductive thin film is used (transparent conductive layer), any conductive film may be used, but a metal oxide film is preferable. Thereby, higher visible light transmittance can be obtained. In the present invention, when it is required to improve the conductivity of the transparent conductive layer, it is recommended that the transparent conductive layer has a repeating structure of three or more layers of metal oxide / metal / metal oxide. By forming a multilayer structure using a metal, conductivity can be obtained while maintaining high visible light transmittance.

The metal oxide used in the present invention may be any metal oxide as long as it has electrical conductivity and visible light transmittance. Examples include tin oxide, indium oxide, indium tin oxide, zinc oxide, titanium oxide, bismuth oxide, and the like. The above is an example, and there is no particular limitation. The metal layer used in the present invention is preferably made of gold, silver or a compound containing them from the viewpoint of conductivity.

Further, in forming the conductive layer according to the present invention into multiple layers, for example, when the number of repeating layers is three, the thickness of the silver layer (metal layer) is preferably 50 to 200 °, more preferably 50 to 100 °. It is. When the film thickness is thicker than this, the light transmittance decreases, and when the film thickness is thinner, the resistance value increases. Further, the thickness of the metal oxide layer is preferably 100 to 1000 °, more preferably 100 to 5 °.
00 °. If the thickness is larger than this thickness, the color is changed and the color tone changes, and if the thickness is smaller, the resistance value increases. Further, when forming three or more layers, for example, metal oxide / silver / metal oxide / silver / metal oxide
In the case of a layer, the thickness of the central metal oxide layer is preferably larger than the thickness of the other metal oxide layers.
By doing so, the light transmittance of the entire multilayer film is improved.

Further, in the present invention, a structure in which a releasable protective film is laminated on one or both surfaces of the film, or a pressure-sensitive adhesive layer is formed on one or both surfaces, and a release film is further laminated thereon. good.

In the present invention, an antireflection layer can be provided as the outermost layer of the near-infrared absorption filter. It is also possible to provide an antiglare layer on the outermost layer of the near-infrared absorbing filter.

In the near-infrared absorbing filter of the present invention, a UV absorber may be added for the purpose of improving light resistance.

When the infrared absorption filter of the present invention is installed in front of the plasma display, unnecessary near infrared rays emitted from the display can be absorbed, and malfunction of the remote control using the near infrared rays can be prevented. In addition, since there is no large absorption at a specific wavelength in the visible region, it can be expressed without changing the color tone emitted from the display.

[0057]

Next, examples of the present invention and comparative examples will be described. The method for measuring characteristic values and the method for evaluating effects used in the present invention are as follows.

<Amount of Residual Solvent in Coat Layer> The amount of residual solvent was measured as follows using GC-9A manufactured by Shimadzu Corporation. About 5 mg of a sample was accurately weighed, and after heating and trapping at 150 ° C. for 5 minutes at a gas chromatograph inlet, the total amount (A: ppm) of toluene, tetrahydrofuran (THF), and methyl ethyl ketone (MEK) was determined.
However, since the peaks of THF and MEK overlap, they were compared with the standard peak (toluene), and the amount in terms of toluene was calculated as the total value. Separately, a sample cut into a square of 10 cm was weighed (B: g), and then the coat layer was wiped off with a solvent, and the mass difference (C: g) between the sample before and after wiping was determined. The residual solvent amount was calculated using the following equation (7). Residual solvent amount (% by mass) = A × B × 10 ⁻⁴ / C (7).

<Spectral Characteristics> Self-recording spectrophotometer (Hitachi U-3)
500 type) in the wavelength range of 1500 to 200 nm.

<Environmental Stability> After the sample was left for 500 hours in an atmosphere of a temperature of 60 ° C. and a humidity of 95%, the above-mentioned spectral characteristics were measured.

Example 1 A polyester-based binder resin was produced in the following manner. In an autoclave equipped with a thermometer and a stirrer, 136 parts by mass of dimethyl terephthalate, 58 parts by mass of dimethyl isophthalate, 96 parts by mass of ethylene glycol, 137 parts by mass of tricyclodecanedimethanol, and 0.09 mass of antimony trioxide Was heated at 170 to 220 ° C. for 180 minutes to perform a transesterification reaction. Next, the temperature of the reaction system was raised to 245 ° C., and the reaction was continued for 180 minutes at a system pressure of 1 to 10 mmHg to obtain a copolymerized polyester resin.

The copolymerized polyester resin obtained had an intrinsic viscosity of 0.4 dl / g and a glass transition temperature of 90 ° C. The copolymer composition ratio by NMR analysis was as follows: terephthalic acid 71 mol%, isophthalic acid 29 mol%, alcohol component ethylene glycol 28 mol%, tricyclodecane dimethanol 72 mol%, Met.

A coating solution having the composition shown in Table 1 was prepared. Further, the prepared coating solution was applied to a thickness of 10
0 μm, highly transparent polyester film base material having an easy-adhesion layer on one side (“Cosmoshine A410 manufactured by Toyobo Co., Ltd.”
0 ") was coated with a gravure roll, and dried for 1 minute while sending hot air at 130 ° C. at a wind speed of 5 m / s. The thickness of the coat layer was 8.0 μm, and the amount of residual solvent in the coat layer was 4.1% by mass. The color of the produced near-infrared absorption filter was dark gray visually. FIG. 1 shows the spectral characteristics. As shown in FIG. 1, a filter having a flat absorption in a visible region from a wavelength of 400 nm to 650 nm and a sharp absorption at a wavelength of 700 nm or more was obtained.

The obtained filter was subjected to a temperature of 60 ° C. and a humidity of 9
When left in a 5% atmosphere for 500 hours and the spectral characteristics were measured again, the results were as shown in FIG. The maximum change rate of the transmittance from a wavelength of 420 nm to 1100 nm was 9.2%.

[0065]

[Table 1]

Example 2 A coating solution having a thickness of 100 μm was used in Example 1.
And a highly transparent polyester film base material having an easy-adhesion layer on one side (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd.)
Was coated with a gravure roll, and dried for 1 minute while sending hot air of 150 ° C. at a wind speed of 5 m / s. The thickness of the coat layer was 10 μm, and the amount of the residual solvent in the coat layer was 2.0% by mass. FIG. 3 shows the spectral characteristics of this filter. As shown in FIG.
A filter having a flat absorption in the visible region from m to 650 nm and a sharp absorption at a wavelength of 700 nm or more was obtained. This filter was heated at a temperature of 60 ° C.
% For 500 hours, and the spectral characteristics were measured again. The result was as shown in FIG. As shown in FIG. 4, no significant change was observed in the spectral curve of the filter, indicating a stable performance. The maximum change rate of the transmittance from a wavelength of 420 nm to 1100 nm was 11.5%.

Example 3 An acrylic binder resin was produced in the following manner.
In a reaction vessel, 60 g of t-butyl methacrylate as a monomer, 120 g of ethyl acetate, and 120 g of methanol
g and azobisisobutyronitrile 0.51 g, and the mixture was reacted for 8 hours while stirring at 60 ° C. under a nitrogen atmosphere.
After the reaction, the reaction solution was added to hexane, and the polymer was reprecipitated to obtain a binder resin. The molecular weight of the obtained binder resin was 100,000. The glass transition temperature was 105 ° C. Next, a coating liquid was prepared with the same composition as in Table 1 except that the acrylic resin prepared for the binder was used.

The prepared coating solution was coated to a thickness of 100 μm
And a highly transparent polyester film base material having an easy-adhesion layer on one side (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd.)
Was coated with an applicator and dried for 30 minutes while sending 100 ° C. hot air at an air velocity of 1 m / s. The residual solvent amount was 3.4% by mass. FIG.
Shows the spectral characteristics of this filter. As shown in FIG. 5, the transmittance was high in the visible region of wavelengths from 400 nm to 650 nm, the absorption in the near infrared region was large, and the spectral characteristics were wide. This filter was left in an atmosphere of a temperature of 60 ° C. and a humidity of 95% for 500 hours, and the spectral characteristics were measured again. The result was as shown in FIG. As shown in FIG. 6, no significant change was observed in the spectral curve of the filter.
It showed stable performance. In addition, from a wavelength of 420 nm to 110
The maximum change in the transmittance at 0 nm was 24.9%.

Comparative Example 1 The coating liquid used in Example 1 was
And a highly transparent polyester film base material having an easy-adhesion layer on one side (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd.)
Was coated with a gravure roll and dried for 1 minute while sending 120 ° C. hot air at a wind speed of 5 m / s. The thickness of the coat layer was 11 μm, and the amount of residual solvent in the coat layer was 6.5% by weight. The visual color was dark gray. FIG. 7 shows the spectral characteristics. As shown in FIG. 7, a filter having a flat absorption in a visible region from a wavelength of 400 nm to 650 nm and having a steep absorption at a wavelength of 700 nm or more was obtained. The filter was left in an atmosphere of 60 ° C. and 95% humidity for 500 hours, and the spectral characteristics were measured again. The result was as shown in FIG. As shown in FIG. 8, the absorption in the near infrared region decreased, and the color of the filter also changed to yellow-green. Further wavelength 420n
The maximum change in transmittance from m to 1100 nm is 154.6.
% Was extremely large.

Comparative Example 2 After coating the coating solution used in Example 1 with an applicator, hot air at 80 ° C. was blown at a velocity of 0.4 m / s.
The same operation as in Example 1 was carried out, except that drying was performed for 30 minutes while feeding in. The thickness of the coat layer was 18 μm, and the amount of residual solvent in the coat layer was 5.9% by weight. The visual color was dark gray. FIG. 9 shows the spectral characteristics.
As shown in FIG. 9, a filter having a flat absorption in a visible region from a wavelength of 400 nm to 650 nm and having a steep absorption at a wavelength of 700 nm or more was obtained. This filter was left in an atmosphere of a temperature of 60 ° C. and a humidity of 95% for 500 hours, and the spectral characteristics were measured again. The result was as shown in FIG. As shown in FIG. 10, the absorption in the near infrared region decreased, and the color of the filter also changed to yellow-green. Further, the maximum change rate of the transmittance from a wavelength of 420 nm to 1100 nm was as large as 91.0%.

[0071]

The near-infrared absorbing filter of the present invention has a large and wide absorption in the near-infrared region, a high light transmittance in the visible region, and a large absorption of a specific wavelength in the visible region. Therefore, it is suitable as a near-infrared absorption filter for optical devices such as video cameras and displays, particularly for plasma displays. In addition, processability and productivity are good, and furthermore, it has excellent environmental stability,
There is an advantage that it can withstand long-time use even under high temperature or high humidity.

[Brief description of the drawings]

FIG. 1 is a diagram showing the spectral characteristics of a near-infrared absorbing filter obtained in Example 1.

FIG. 2 is a diagram showing the spectral characteristics of the near-infrared absorbing filter obtained in Example 1 after being left in an atmosphere at a temperature of 60 ° C. and a humidity of 95% for 500 hours.

FIG. 3 is a diagram showing spectral characteristics of a near-infrared absorption filter obtained in Example 2.

FIG. 4 is a diagram showing spectral characteristics of the near-infrared absorbing filter obtained in Example 2 after being left in an atmosphere at a temperature of 60 ° C. and a humidity of 95% for 500 hours.

FIG. 5 is a diagram showing the spectral characteristics of a near-infrared absorbing filter obtained in Example 3.

FIG. 6 is a diagram showing spectral characteristics after the near-infrared absorbing filter obtained in Example 3 was left in an atmosphere at a temperature of 60 ° C. and a humidity of 95% for 500 hours.

FIG. 7 is a diagram showing spectral characteristics of a near-infrared absorbing filter obtained in Comparative Example 1.

FIG. 8 is a view showing the spectral characteristics of the near-infrared absorbing filter obtained in Comparative Example 1 after being left in an atmosphere at a temperature of 60 ° C. and a humidity of 95% for 500 hours.

FIG. 9 is a diagram showing the spectral characteristics of the near-infrared absorbing filter obtained in Comparative Example 2.

FIG. 10 is a diagram showing spectral characteristics of the near-infrared absorbing filter obtained in Comparative Example 2 after being left in an atmosphere at a temperature of 60 ° C. and a humidity of 95% for 500 hours.

[Explanation of symbols]

 Wavelength (nm) Wavelength when measuring spectral characteristics Transmittance (%) Light transmittance when measuring spectral characteristics

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanori Kobayashi 2-1-1 Katata, Otsu-shi, Shiga Inside Toyobo Co., Ltd. Research Institute (72) Inventor Seiichiro Yokoyama 2-1-1 Katata, Otsu-shi, Shiga Toyobo Co., Ltd. Research Laboratory F-term (reference) 2H048 CA04 CA12 CA19

Claims (14)

[Claims] 1. A near-infrared absorbing filter formed by laminating a coat layer comprising a composition in which a near-infrared absorbing dye is dispersed in a binder resin on a substrate, wherein the transmittance is represented by the following formula (1): A maximum value of a rate of change V (%) of the near-infrared absorption filter is 25% or less. V = 100 × | T _{0 (WL)} −T _{1 (WL)} | / T _{0 (WL)} (1) where T _{0 (WL)} : transmittance at wavelength WL T _{1 (WL)} : The transmittance at a wavelength WL after storage at a temperature of 60 ° C. and a humidity of 95% for 500 hours, where WL represents each wavelength from 420 nm to 1100 nm. 2. The near-infrared absorbing filter according to claim 1, wherein the binder resin has a glass transition temperature of 85 to 140 ° C. 3. The near-infrared absorbing dye according to the following formula (2)
The near-infrared absorption filter according to claim 1, comprising a diimonium salt compound represented by the following formula: Embedded image (Wherein, R _{1 to} R ₈ represent a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, an aralkyl group, or an alkynyl group, and may be the same or different.
₉ to R ₁₂ is a hydrogen atom, a halogen atom, an amino group, a cyano group, a nitro group, a carboxyl group, an alkyl group, an alkoxy group, be each the same or may be different. Those capable of bonding a substituent at R _{1 to} R ₁₂ may have a substituent. X ^- represents an anion. ) 4. The near-infrared absorbing filter according to claim 1, wherein the near-infrared absorbing dye contains a fluorinated phthalocyanine compound and / or a dithiol metal complex compound. 5. The near-infrared absorbing filter according to claim 4, wherein the dithiol metal complex-based compound is a compound represented by the following formula (3). Embedded image (R _{13 to} R ₁₆ are a hydrogen atom, a halogen atom, an alkyl group,
Represents an alkoxyl group, an aryl group, an aralkyl group, or an amino group, which may be the same or different. ) 6. The substrate according to claim 1, wherein the substrate is a transparent substrate.
A near-infrared absorption filter according to any one of claims 1 to 5. 7. The near-infrared absorbing filter according to claim 6, wherein the transparent substrate is a polyester film. 8. The near-infrared absorbing filter according to claim 1, wherein a peelable protective film is further laminated on one or both sides. 9. The method according to claim 1, wherein a release film is laminated on one or both sides of the release film via an adhesive layer.
9. The near-infrared absorption filter according to any one of items 1 to 8. 10. An aperture ratio of 50 on one or both sides.
The near-infrared absorption filter according to any one of claims 1 to 9, wherein a metal mesh conductive layer of at least% is laminated. 11. The near-infrared absorbing filter according to claim 1, wherein a transparent conductive layer is further laminated on one or both sides. 12. The near-infrared absorbing filter according to claim 1, wherein an anti-reflection layer is further laminated on the outermost layer. 13. The near-infrared absorbing filter according to claim 1, wherein an antiglare treatment layer is further laminated on the outermost layer. 14. The near-infrared absorbing filter according to claim 1, which is installed on a front surface of the plasma display.