JP2001158762A - Near infrared ray absorbing compound and near infrared ray absorbing filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a near infrared ray absorbing compound having high and wide absorption in a near infrared ray region having a wavelength ranging from 800 nm to 1,300 nm, high in light transmissivity in a visible region and not having high absorption of any wavelength in a visible region, and to provide a near infrared ray absorbing filter excellent in processability and productivity by using a near infrared ray absorbing compound having the above characteristics. SOLUTION: This near infrared ray absorbing compound has a molecular structure represented by general formula (1) (wherein R1 to R5 are each a substituent; and X is a counterion for neutralization). This infrared ray absorbing filter features laminating on a substrate a resin composition where the above near infrared ray absorbing compound is dispersed in a polymer resin.

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 absorbing filter having a high transmittance in a visible light region and capable of efficiently blocking near-infrared rays. The present invention also relates to a novel near-infrared absorbing compound for obtaining the near-infrared absorbing filter. The near-infrared absorbing filter using the near-infrared absorbing compound of the present invention is, for example, light-receiving sensitivity correction and color correction of light-receiving elements and imaging elements of optical devices such as video cameras, and forgery prevention of cash cards and ID cards. It can be widely applied to applications requiring a function of blocking near infrared rays. It can also be used as a dimming material for absorbing near-infrared rays contained in sunlight, an agricultural material for controlling plant growth, a visual protection medical material such as protective glasses, and a photosensitive material.

[0002]

2. Description of the Related Art Typical near-infrared absorbing compounds and near-infrared absorbing filters that have been used in the past include:
The following are mentioned.

[0003] Filters containing phosphoric acid glass containing metal ions such as copper and iron (Japanese Patent Application Laid-Open Nos. 60-235740 and 62-153144).

[0004] Interference filters that transmit specific wavelengths by laminating layers having different refractive indices on a substrate and causing transmitted light to interfere (Japanese Patent Application Laid-Open Nos. 55-21091 and 59-91).
184745).

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

The following materials have been used as near infrared absorbing materials containing near infrared absorbing dyes. (1) JP-A-8-120186, JP-A-9-2
Phthalocyanine and naphthalocyanine dyes as disclosed in JP-A-79125 and JP-A-8-120186. (2) JP-A-60-43605, JP-A-61-1
No. 15958, Japanese Unexamined Patent Publication No. 61-291651,
JP-A-62-132963, JP-A-1-17224
No. 58, using an anthraquinone-based dye as disclosed in JP-A-58-58. (3) JP-A-60-236131, JP-A-4-1
No. 74403 using an aminium salt dye as described in JP-A-74403. (4) JP-A-57-21458, JP-A-61-21
No. 32003, JP-A-62-187302, JP-B-61-32003, JP-A-61-32
No. 003 using a dithiol metal complex dye as described in JP-A-003. (5) JP-A-5-178808, JP-A-5-29
No. 5967, and those using a diimmonium salt dye as disclosed in JP-A-9-310031.

However, the above-described near-infrared absorbing filters which have been conventionally used have the following problems.

In the case of the above-mentioned method, there is a steep absorption in the near-infrared region, and the infrared cutoff rate is very good. However, a part of red in the visible region is also largely absorbed, and the transmission color is blue. appear. In display applications, color balance is emphasized, and it is inappropriate to use in such applications. Moreover, since it is glass, there is a problem in workability.

In the case of the above-mentioned method, the optical characteristics can be freely designed, and a filter having a quality almost as designed can be manufactured. There is a drawback that it needs to be very large, and the production cost becomes high. Further, when a large area is required, it is difficult to manufacture because a high-accuracy film thickness uniformity is required over the entire area.

In the case of the above method, the workability, which is a disadvantage of the above method, is improved. However, similarly to the above-mentioned method, the degree of freedom in designing optical characteristics is low. Further, the problem of the above-described method that the red portion in the visible region also has absorption and the filter looks blue remains unchanged. 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.

In the case of the above-mentioned method, the workability and productivity are excellent, and it can be manufactured at low cost, and the degree of freedom in designing optical characteristics is relatively large. However, the infrared absorbing dyes described above which have been conventionally used have the following problems.

When the infrared absorbing dye described in the above (1) is used, absorption in the visible region is large and only a colored product can be obtained. Further, the absorption width in the near-infrared region is small, and the blocking of near-infrared rays is insufficient.

When the infrared absorbing dye described in the above (2) is used, the absorption in the visible region is large and the product is colored, as in the case where the infrared absorbing dye described in the above (1) is used.

When the infrared absorbing dye described in the above (3) is used, although the absorption width in the near infrared region is large, there is a large absorption in the visible region, so that coloring becomes a problem.

When the infrared-absorbing dye described in (4) is used, the absorption in the visible region is smaller than that of other dyes, but the absorption width in the near-infrared region is small and the blocking of near-infrared light is insufficient.

The use of the infrared-absorbing dye described in (5) has the advantage that the problem of coloring is small because the absorption in the visible region is relatively small, and the absorption width in the near-infrared region is wide. However, the wavelength range of the infrared remote control is 8
There is a problem that absorption from 00 nm to 900 nm is insufficient.

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 are emitted from the plasma display, which 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. But,
In fact, it has not been possible to provide satisfactory materials with the materials conventionally used for the reasons described above.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to have a large and wide absorption in the near infrared region at a wavelength of 800 nm to 1300 nm; Another object of the present invention is to provide a near-infrared absorbing compound which has high light transmittance in a visible region and does not have a large absorption of a specific wavelength in a visible region.
Further, using a near infrared absorbing compound having the above characteristics,
An object of the present invention is to provide a near-infrared absorbing filter having excellent processability and productivity.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and a near-infrared absorbing compound and a near-infrared absorbing filter which can solve the above-mentioned problems are as follows. It is on the street.

The first invention of the present invention is a near infrared absorbing compound having a molecular structure represented by the following general formula (1).

Embedded image Here, R1 to R5 are substituents, and X is a counter ion for neutralization.

According to a second aspect of the present invention, there is provided a resin composition in which the near-infrared absorbing compound according to the first aspect is dispersed in a polymer resin, wherein the resin composition is laminated on a substrate. This is a near infrared absorption filter. A third invention is a near-infrared absorption filter, wherein the substrate according to the second invention has substantially no absorption in a visible light region.

A fourth invention is the near-infrared absorbing filter according to the third invention, wherein the substrate is a transparent polyester film. A fifth invention is the near-infrared absorption filter according to the second to fourth inventions, wherein the near-infrared absorption filter is provided on the front surface of the plasma display.

[0023]

Embodiments of the present invention will be described below in detail.

In the present invention, the near-infrared absorbing compound represented by the general formula (1) is prepared by a method described in the literature (Shig
eru Sasaki and Masahiko Iyoda, Chemistry Letters,
1995), for example, by synthesizing a compound represented by the following structural formula (2) and oxidizing this compound. Oxidation is performed using AgClO ₄ , AgS
With an oxidizing agent such as bF ₆ , AgBF ₄ , AgNO ₃
It can be done easily.

[0025]

Embedded image Here, R1 to R5 are substituents.

The near-infrared absorbing compound of the present invention represented by the general formula (1) has a large absorption in the near-infrared region and a large absorption width. In addition, it has a high transmittance in the visible region and is suitable for optical applications. In addition, the substituents R1 to R
By means of 5, fine adjustment of the absorption wavelength range and control of solubility in the polymer resin can be performed.

In the near-infrared absorbing compound of the present invention, all of the substituents R1 to R5 in the above formula (1) may be the same, but are not particularly limited. Also,
The substituents R1 to R4 are preferably substituted at the 4-position of the nitrogen atom. As the substituents R1 to R5, an alkyl group,
An aryl group, an alkoxy group, an alkenyl group, an aralkyl group, and others include hydrogen, fluorine, chlorine, bromine, and a cyano group. X represents a counter ion for neutralization.

Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a t-butyl group, an 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, trifluoromethyl group, etc. Is mentioned.

The aryl group includes a phenyl group, a fluorophenyl group, a chlorophenyl group, a tolyl group, a diethylaminophenyl and a naphthyl group, and the alkenyl group includes a vinyl group, a propenyl group, a butenyl group and a pentenyl group, and an aralkyl group. Examples thereof include a benzyl group, a p-fluorobenzyl group, a p-chlorophenyl group, a phenylpropyl group, a naphthylethyl group and the like.

As the alkoxy group, a methoxy group,
Examples include ethoxy, n-propoxy, iso-propoxy, n-butoxy, iso-butoxy, n-butoxy, and ter-butoxy. However, the present invention is not limited to these substituents.

The near-infrared absorbing filter of the present invention has a structure in which a near-infrared absorbing layer is laminated on a substrate. The near-infrared absorbing layer is mainly composed of a near-infrared absorbing compound having a molecular structure represented by the general formula (1) and a polymer resin,
It is used by dispersing a near infrared absorbing compound in a polymer resin. In the present invention, by adopting such a configuration, it is easy to control the thickness of the near-infrared absorbing layer and the content of the near-infrared absorbing compound represented by the general formula (1). The degree of absorption and the transmittance in the visible region can be controlled, and the degree of freedom in designing optical characteristics can be increased.

The method of laminating the near-infrared absorbing layer on the substrate is not particularly limited, but a gravure coating method, a reverse coating method,
It can be provided by a kiss roll coating method or a roll coating method, and is excellent in workability and productivity. The near-infrared absorbing layer of the present invention needs to contain at least one kind of near-infrared absorbing compound having a molecular structure represented by the general formula (1). When two or more near-infrared absorbing compounds having different absorption wavelengths are used in combination, these near-infrared absorbing compounds may be contained in the near-infrared absorbing layer in a mixed state as long as these near-infrared absorbing compounds do not cause interaction between molecules. . When an interaction or the like occurs between molecules, it is necessary to use each alone. In that case, a plurality of near-infrared absorbing layers each containing a single near-infrared absorbing compound having a different absorption wavelength may be laminated on the substrate. This lamination may be performed on both sides of the substrate, or a plurality of layers may be laminated on one side.

In the near-infrared absorbing layer of the near-infrared absorbing filter of the present invention, in addition to the compound represented by the above-mentioned general formula (1), the near-infrared absorbing region may be used if it does not show any interaction between molecules. For the purpose of widening the width and increasing the absorption strength, another near-infrared absorbing compound may be contained.

As other near-infrared absorbing compounds, phthalocyanine compounds, dithiol metal complex compounds, diimmonium salt compounds and the like are preferred. For example, phthalocyanine-based compounds include Excolor IR manufactured by Nippon Shokubai Co., Ltd.
-1, IR-2, IR-3, IR-4, TXEX-805K, TXEX-809K, TXEX-8
10K, TXEX-811K, TXEX-812K, and the like. Also,
As a dithiol metal complex compound, SI manufactured by Mitsui Chemicals, Inc.
Examples are R-128, SIR-130, SIR-132, SIR-159, and the like. Further, examples of diimmonium salt-based compounds include IRG-022 and IRG-023 manufactured by Nippon Kayaku.

The above-mentioned other near-infrared absorbing compounds are merely examples and are not particularly limited. If necessary, other types of dyes may be mixed.

The polymer resin which is a component of the near-infrared absorbing layer is not particularly limited as long as it can uniformly disperse the near-infrared absorbing compound of the present invention represented by the general formula (1). , Polyester, acrylic,
Polyamide-based, polyurethane-based, polyolefin-based, and polycarbonate-based resins are preferred.

The substrate is preferably a plastic film in terms of cost and ease of handling as well as high transparency. Specifically, a film formed from a polyester-based, acrylic-based, cellulose-based, polyethylene-based, polypropylene-based, polyolefin-based, polyvinyl chloride-based, polycarbonate, phenol-based, or urethane-based resin is used. However, from the viewpoint of physical properties, optical properties, chemical resistance, environmental load, etc.,
Polyester films are preferred. As the polyester film, a biaxially oriented polyester film formed of polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate or a copolymer containing a main component of these resins as a main component is preferable. The formed biaxially oriented polyethylene terephthalate film is particularly preferred.

Further, the polyester resin may contain various additives. Examples of the additive include an antistatic agent, a UV absorber, and a stabilizer.
In addition, it is preferable that substantially no inert particles for imparting lubricity are contained in the base polyester film from the viewpoint of transparency.

In order to improve the adhesion between the base film and the near-infrared absorbing layer, it is preferable that an easy-adhesion layer is previously laminated on the base film on the surface on which the near-infrared absorbing layer is to be laminated. . Above all, it is particularly preferable to provide an easy-adhesion layer on at least one surface of the unstretched or uniaxially stretched polyester film, and then laminate by an inline coating method in which the film is stretched and heat-fixed in at least one axis direction. In the easy adhesion layer laminated by the in-line coating method,
By providing fine particles having an appropriate particle size to impart slipperiness, good handling properties (slipperiness, winding property, etc.) and scratch resistance can be imparted.
For this reason, it is not necessary to include fine particles in the biaxially oriented polyester, and a highly transparent film having a total light transmittance of 89% or more can be obtained.

As the resin of the easy-adhesion layer, copolymerized polyester resin, polyurethane resin, acrylic resin, styrene-maleic acid graft polyester resin,
Acrylic graft polyester resin and the like can be mentioned, and it is preferable to use at least one or more kinds. Among them, a resin composed of a copolymerized polyester resin and a polyurethane resin, and a styrene-maleic acid-grafted polyester resin are particularly preferable.

In the present invention, the method of laminating the resin composition in which the near-infrared absorbing composition is dispersed in a binder resin on a substrate includes, but is not particularly limited to, a coextrusion method and a coating method. Among them, the coating method is preferable in terms of thickness uniformity and cost. In the case of the coating method, the solvent used for the coating liquid 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,
Examples include, but are not limited to, butyl cellosolve, benzene, toluene, xylene, tetrahydrofuran, n-hexane, n-heptane, methylene chloride, chlorophorom, N, N-dimethylformamide, water, and the like.

[0042]

Next, a method for producing a near-infrared ray absorbing compound and a near-infrared ray absorbing filter of the present invention will be described with reference to polyethylene terephthalate (hereinafter abbreviated as PET) as a substrate.
Will be described as an example, but the present invention is not limited to this. “Parts” in Examples and Comparative Examples are “parts by weight” unless otherwise specified. Further, the spectral characteristics described in this specification are based on a self-recording spectrophotometer (Hitachi U-350).
0), and the measured wavelength is 1
The range is from 500 to 200 nm.

Example 1 A compound represented by the following structural formula (3) was prepared by a method described in a literature (Shig
eru Sasaki and Masahiko Iyoda, Chemistry Letters,
1995). Next, 1 part of the compound represented by the following structural formula (3) was dissolved in 20 parts of acetone, and a 2-fold molar amount of silver hexafluoroantimonate was added to the compound. After stirring at room temperature for 2 hours, the precipitated silver was separated by filtration, the filtrate was diluted with ether, the precipitated solid was collected, washed with ether and hexane, and the near-infrared absorbing compound 0 represented by the following structural formula (4) was added. 0.5 parts were obtained. This near-infrared absorbing compound was dissolved in a methylene chloride solution, a 10 mg / l solution was prepared, and the solution was placed in a 1 cm long quartz cell, and the transmittance was measured by a spectrophotometer. Table 2
As shown in the above, the near-infrared absorbing compound represented by the following structural formula (4) had a high transmittance in the visible region at 550 nm, and also had a large absorption in the near-infrared region from 800 nm to 900 nm.

[0044]

Embedded image Here, n-Bu is an abbreviation for n-butyl group.

[0045]

Embedded image Here, n-Bu is an abbreviation for n-butyl group.

Example 2 A polymer resin in which the above-mentioned near-infrared absorbing compound was dispersed was produced in the following manner. In an autoclave equipped with a thermometer and a stirrer, 136 parts by weight of dimethyl terephthalate, 58 parts by weight of dimethyl isophthalate 96 parts by weight of ethylene glycol, 137 parts by weight of tricyclodecane dimethanol 0.09 part by weight of antimony trioxide The part was charged and heated at 170 to 220 ° C. for 180 minutes to perform a transesterification reaction. Next, the temperature of the reaction system was set to 245 ° C.
Then, the reaction was continued for 180 minutes at a system pressure of 1.33 to 13.3 hPa to obtain a copolymerized polyester resin (A1). Copolyester resin (A
The intrinsic viscosity of 1) was 0.40 dl / g, and the glass transition temperature was 90 ° C.

The above-mentioned copolymerized polyester resin (A1)
The copolymer composition ratio by NMR analysis was as follows: 71 mol% of terephthalic acid and 29 mol% of isophthalic acid as acid components, and 28 mol of ethylene glycol as alcohol component.
Mol%, tricyclodecane dimethanol was 72 mol%.

Next, the copolymerized polyester resin (A
1) A near-infrared absorbing compound represented by the structural formula (4) described in Example 1 and a solvent were placed in a flask having a composition shown in Table 1, and the mixture was stirred while heating. The polymerized polyester resin (A1) was dissolved. This solution was used as a coating solution for the near infrared absorbing layer.

[0049]

[Table 1]

Next, the coating solution prepared above was applied to a layer having a thickness of 10
0 μm highly transparent biaxially oriented polyethylene terephthalate film substrate (Cosmo Shine A4 manufactured by Toyobo Co., Ltd.)
100), coated on one side with a gravure roll and dried for 1 minute while sending hot air at 150 ° C. to the film surface at an air velocity of 5 m / s to produce a near infrared absorbing filter. The thickness of the coating layer (near-infrared absorbing layer) after drying was 8.0 μm. Table 1 shows the spectral characteristics of the obtained near-infrared absorbing filter. As shown in Table 1, the obtained near-infrared absorbing filter had a high transmittance in the visible region at 550 nm and a large absorption in the near-infrared region from 800 nm to 900 nm.

Example 3 A near-infrared absorbing compound represented by the following structural formula (5) was
The synthesis was performed in the same manner as in the synthesis method described in Example 1. Next, Example 2 was repeated except that this near-infrared absorbing compound was used.
A near-infrared absorbing filter was manufactured in the same manner as in Example 1 and the spectral characteristics were measured. As shown in Table 1, the obtained near-infrared absorbing filter had a high transmittance in the visible region at 550 nm and a large absorption from 800 nm to 900 nm.

[0052]

Embedded image Here, n-Bu is an abbreviation for n-butyl group.

Example 4 A near-infrared absorbing compound represented by the following structural formula (6) was synthesized in the same manner as in the synthesis method described in Example 1. Next, a near-infrared absorbing filter was manufactured in the same manner as in Example 2 except that this near-infrared absorbing compound was used, and its spectral characteristics were measured. As shown in Table 1, the obtained near-infrared absorption filter has a high transmittance at 550 nm in the visible region,
The absorption from 800 nm to 900 nm was also large.

[0054]

Embedded image

Comparative Example 1 A near-infrared absorbing compound was changed to a diimmonium salt-based compound (IRG-022, manufactured by Nippon Kayaku Co., Ltd.).
The spectral characteristics were measured in the same manner as in Example 1. As shown in Table 1, the diimmonium salt-based compound had high transmittance in the visible region at 550 nm, but had insufficient absorption in the near infrared region from 800 nm to 900 nm.

Comparative Example 2 A diimmonium salt compound (IRG-022, manufactured by Nippon Kayaku Co., Ltd.) was used as the near-infrared absorbing compound, except that
The spectral characteristics were measured in the same manner as in Example 2. As shown in Table 1, although the obtained near-infrared absorption filter had a high transmittance in the visible region at 550 nm, the absorption in the near-infrared region from 800 nm to 900 nm was insufficient.

[0057]

[Table 2]

[0058]

As described above, the near-infrared absorbing compound and near-infrared absorbing filter of the present invention have a large absorption in the near-infrared region, a wide absorption, and a high light transmittance in the visible region. In addition, since it has excellent environmental stability and durability, it can be used for near-infrared absorption filters for plasma displays, wavelength-selective dimming materials, visual protection medical materials, and other optical communication and light detection devices. It is suitable for an infrared cut filter, a near infrared photosensitive material, a wavelength selective near infrared cut filter for agricultural use, and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C07C 211/56 C07C 211/56 217/92 217/92 C09K 3/00 105 C09K 3/00 105 G02B 5 / 22 G02B 5/22 F term (reference) 2H048 CA04 CA12 CA19 CA29 FA01 FA15 FA22 4F100 AH03A AK01A AK41B AL01A AT00B BA02 BA15 CA30A GB41 JD14A JL00 JL01 JL02 JN01B 4H006 AA01 AA03 AB92

Claims (5)

[Claims] 1. A near-infrared absorbing compound having a molecular structure represented by the following general formula (1). Embedded image Here, R1 to R5 are substituents, and X is a counter ion for neutralization. 2. A near-infrared absorbing filter, comprising: a resin composition in which the near-infrared absorbing compound according to claim 1 is dispersed in a polymer resin, wherein the resin composition is laminated on a base material. 3. A near-infrared absorbing filter, wherein the substrate according to claim 2 has substantially no absorption in a visible light region. 4. The near-infrared absorbing filter according to claim 3, wherein the substrate is a transparent polyester film. 5. The near-infrared absorbing filter according to claim 2, wherein the near-infrared absorbing filter is installed on a front surface of the plasma display.