JPH11305033A - Infrared ray absorption filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a filter have absorption in a near-infrared ray region, to improve the light transmissivity in a visible region and to prevent the filter from having the large absorption of a specified wavelength in the visible region by making the transmissivity in the near infrared ray region of a specified wavelength range less than a specified value. SOLUTION: For this infrared-ray absorption filter, the transmissivity in a near infrared-ray region of a wavelength 800 nm-1,100 nm is less than 30%. Since the transmissivity in this area is low, in the case of using it in a plasma display or the like, unrequired infrared rays emitted from the display are absorbed and the malfunction of a remote controller using the infrared rays is prevented. Also, it is desirable that the difference of the maximum value and minimum value of the transmissivity in the visible region of the wavelength 450 nm-650 nm be within 10%. When the transmissivity difference of the wavelength 450 nm-650 nm is within the range, the color tone becomes gray and in the case of placing it on the display front surface, the color tone emitted from the display is expressed without being changed. Further, it is preferable that the transmissivity of the wavelength 550 nm is more than 50%.

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 an optical filter having a high transmittance in a visible light region and blocking infrared rays.

[0002]

2. Description of the Related Art Conventionally, the following materials have been widely used as a heat ray absorption filter, a video camera visibility correction filter, and the like. (1) Filters containing phosphoric acid-based glass and metal ions such as copper and iron (JP-A-60-235740;
(2) Layers having different refractive indices are laminated on a substrate, and an interference filter that transmits a specific wavelength by causing transmitted light to interfere (Japanese Patent Laid-Open Nos. 55-21091 and 59-184745).
(3) Acrylic resin filter containing copper ions in the copolymer (JP-A-6-324213) (4) Filter having a structure in which a pigment is dispersed in a binder resin (JP-A-57-21458, JP-A-57-21857) -19841
3, JP-A-60-43605, etc.)

[0003]

The above-mentioned conventionally used infrared absorption filters have the following problems. In the above-mentioned method (1), absorption is sharp in the near-infrared region, and the infrared cutoff rate is very good.
Part of the red in the visible region is also greatly absorbed, and the transmitted color looks blue. In display applications, color balance is emphasized, and in such a case, it is difficult to use. Moreover, since it is glass, there is a problem in workability. In the case of the above-mentioned method (2), the optical characteristics can be freely designed, and a filter almost equivalent to the designed one can be manufactured.
For this reason, there is a disadvantage that the number of layers having a difference in the refractive index becomes extremely large and the manufacturing cost becomes high. In addition, when a large area is required, high-accuracy film thickness uniformity is required over the entire area, and manufacturing is difficult. In the case of the method (3), the workability of the method (1) is improved. However, similar to the method (1), although there is a steep absorption characteristic, the problem that the red portion also absorbs and the filter looks blue remains unchanged. In the method (4), many infrared absorbing dyes such as phthalocyanine, nickel complex, azo compound, polymethine, diphenylmethane, triphenylmethane, and quinone are used. However, each of them has problems such as insufficient absorption and absorption of a specific wavelength in the visible region. Furthermore, if the filter is left under high temperature or humidification for a long time, there is a problem that the decomposition and oxidation of the dye occur, absorption in the visible region occurs, and absorption in the infrared region disappears. .

[0004]

SUMMARY OF THE INVENTION The present invention has an absorption in the near-infrared region, a high light transmittance in the visible region, and does not have a large absorption of a specific wavelength in the visible region. The object of the present invention is to provide a near-infrared absorption filter having good productivity and productivity. That is, the present invention provides a wavelength of 800 nm to 1100 nm.
Wherein the transmittance in the near infrared region is 30% or less. Due to the low transmittance in this region, when used for a plasma display or the like, unnecessary infrared rays radiated from the display can be absorbed and malfunction of a remote controller using infrared rays can be prevented. Also,
In the present invention, it is desirable that the difference between the maximum value and the minimum value of the transmittance in the visible region of a wavelength of 450 nm to 650 nm is within 10%. When the transmittance difference between the wavelengths of 450 nm and 650 nm is within this range, the color tone becomes gray, and when placed in front of the display, the color tone emitted from the display can be expressed without change. Furthermore, in the present invention, the transmittance at a wavelength of 550 nm is preferably 50% or more. If the transmittance in the long range is 50% or less, the display becomes very dark when installed on the front of the display. In the present invention, it is preferable that an infrared absorbing dye is dispersed in a polymer, and this is further coated on a transparent substrate.
With such a configuration, the production becomes simple,
It is also possible to handle small lot production. Further, the polymer for dispersing the dye according to the present invention preferably has a glass transition temperature that is higher than or equal to the assumed guaranteed temperature at which the filter of the present invention is used. Thereby, the stability of the dye is improved.
The infrared-absorbing dye used in the present invention is not particularly limited, but the following may be mentioned as an example.

[0005] Nippon Kayaku Kayasorb IRG-022, IRG
-023, Nippon Shokubai ExcolorIR1, IR2, IR3, IR
4, Mitsui Chemicals SIR-128, SIR-130, SIR-132, SIR-
159, and the like, but the infrared absorbing dye is only an example, and is not particularly limited.

In the present invention, the transparent substrate used for coating the substrate with a polymer in which an infrared absorbing dye is dispersed is not particularly limited, but polyester, acrylic, cellulose, polyethylene Examples thereof include a resin, a polypropylene, a polyolefin, a polyvinyl chloride, a polycarbonate, a phenol, and a urethane resin, and a polyester resin is particularly preferable from the viewpoint of dispersion stability, environmental load, and the like.

In the infrared absorbing filter of the present invention, it is preferable to add a UV absorber for the purpose of improving light resistance. Furthermore, in the present invention, in order to impart weather resistance and solvent resistance, a polymer dispersing an infrared absorbing dye,
Crosslinking may be performed using a crosslinking agent.

Example 1 A base polyester as a dispersion medium 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 raised to 245 ° C., and the reaction was continued for 180 minutes at a system pressure of 1 to 10 mmHg, thereby obtaining a copolymerized polyester resin (A1).

The copolymerized polyester resin (A1) had an intrinsic viscosity of 0.4 and a glass transition temperature of 90 ° C. Also NM
The copolymer composition ratio by R analysis was 71 mol% of terephthalic acid and 29 mol% of isophthalic acid with respect to the acid component, 28 mol% of ethylene glycol with respect to the alcohol component, and 72 mol% of tricyclodecane dimethanol.

Next, an infrared absorbing dye, a prepared resin and a solvent having the composition shown in Table 1 were put into a flask, and the resulting mixture was stirred with heating to dissolve the dye and the binder resin. Further, the dissolved resin is applied to a highly transparent polyester film substrate (Cosmo Shine A410 manufactured by Toyobo Co., Ltd.).
0) was coated using an applicator having a gap of 100 μm, and dried at a drying temperature of about 90 ° C. for 1 hour. At this time, the coating thickness was about 25 μm. The color of the obtained infrared absorbing film was dark gray visually. FIG. 1 shows the spectral characteristics. FIG.
As shown in Fig. 7, a film was obtained in which the absorption was flat in the visible region from a wavelength of 400 nm to 650 nm, and the absorption was sharp at a wavelength of 700 nm or more.

[0011] The obtained film is placed at 60 ° C in a 95% atmosphere.
When left for 00 hr and the spectral characteristics were measured again, the results were as shown in FIG. 2. Although a slight color change was observed, the near-infrared absorption characteristics were maintained.

When the obtained film was disposed on the front surface of a plasma display or the like, there was no change in color, the contrast was improved, and the emission of near-infrared rays was reduced.

[0013]

[Table 1]

[0014]

[Table 2]

Comparative Example 1 An infrared absorbing dye, a binder resin, and a solvent having a composition as shown in Table 2 were used in a flask using Toyobo Byron RV200 (specific gravity: 1.26, glass transition temperature: 67 ° C.) as a base polymer. The mixture was stirred while heating to dissolve the dye and the binder resin. Next, the melted resin was coated on a highly transparent polyester film substrate (Cosmoshine A4100 manufactured by Toyobo Co., Ltd.) using an applicator having a gap of 100 μm, and dried at a drying temperature of about 90 ° C. for 1 hour. The coating thickness was about 25 μm. The obtained infrared absorbing film had a visual coloration of brown. FIG. 3 shows the spectral characteristics. As shown in FIG.
An infrared absorbing film having a mountain-like characteristic having a peak at about 550 nm in the visible region up to nm was obtained.
The obtained film was left for 500 hours in an atmosphere of 60 ° C. and 95%, and the spectral characteristics were measured again. As a result, absorption in the near infrared region was lost. Also, the appearance had changed to green. In addition, when the obtained film was placed on the front surface of a plasma display or the like, the color balance was lost, and the color became greenish.

[0016]

According to the present invention, an infrared absorption filter which has a wide absorption in the near-infrared region and a high transmittance in the visible region and does not significantly absorb a specific visible region wavelength can be obtained. Even with little color shift. In addition, it is found that it has excellent environmental stability and can be used for a long period of time.

[Brief description of the drawings]

FIG. 1 shows the spectral characteristics of an infrared absorption filter obtained in Example 1.

FIG. 2 shows the spectral characteristics of the infrared absorption filter obtained in Example 1 after a moisture and heat resistance test.

FIG. 3 shows the spectral characteristics of the infrared absorption filter obtained in Comparative Example 1.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yozo Yamada 2-1-1 Katada, Otsu City, Shiga Prefecture Toyobo Co., Ltd. Research Laboratory

Claims (7)

[Claims] 1. An infrared absorbing filter characterized in that the transmittance in the near infrared region of wavelengths from 800 nm to 1100 nm is 30% or less. 2. The filter according to claim 1, wherein the wavelength is 450 nm.
The difference between the maximum and minimum transmittance in the visible region of 650 nm is 1
An infrared absorption filter characterized by being within 0%. 3. An infrared absorbing filter according to claim 2, wherein the transmittance of the filter at a wavelength of 550 nm is 50% or more. 4. An infrared absorbing filter comprising a transparent base material coated with a polymer in which the dye or dye for absorbing infrared light according to claim 1 is dispersed. 5. An infrared absorption filter wherein the polymer according to claim 1 is a polyester resin. 6. An infrared absorption filter, wherein the transparent substrate according to claim 1 is a polyester film. 7. An infrared absorption material, wherein a glass transition temperature of a polymer used as a dispersion medium for dispersing the dye according to any one of claims 1 to 6 is equal to or higher than a use guarantee temperature of a device using the filter. filter.