Infrared absorption filter

Abstract

The infrared absorption filter of the present invention has a transmittance of not higher than 30% in the near-infrared region in the wavelength range of 800 to 1100 nm; a difference of 10% or less between a maximum value and a minimum value of transmittance in the visible light region in the wavelength range of 450 to 650 nm; and a transmittance of not lower than 50% at a wavelength of 550 nm, the filter being so excellent in environmental stability that after being left to stand in the air atmosphere at a temperature of 60° C. and a humidity of 95% for 1000 hours, the filter can maintain said spectral property in said range. Consequently, when used for a plasma display or the like, the filter can absorb the unwanted infrared rays radiated from the display, resulting in preventing erroneous operation of a remote control using infrared radiation even in such a high-temperature and high-humidity environment. The filter is gray in color so that when placed in front of a display, the color originated in the display can be seen without discoloration.

Description

Hot air temperature:≧80°C.  (3)
Drying time:

Binder resins for use herein are not limited insofar as they can uniformly disperse the near-infrared-absorbing material used in the invention. Suitable examples include, for example, polyester resins, acrylic resins, polyamide resins polyurethane resins, polyolefin resins, polycarbonate resins and the like. Desirably the binder resin for dispersing the near-infrared-absorbing material(s) has a glass transition temperature which is not less than the assumed guaranteed temperature for use of the filter of the invention. Thereby the stability of the near-infrared-absorbing material is increased. The assumed guaranteed temperature for use of the filter of the invention is preferably 80° C. or higher, more preferably 85° C. or higher.

Solvents useful in preparing a coating solution in the coating process can be any solvent insofar as they can uniformly disperse the near-infrared-absorbing material and the binder for use herein. Examples of useful solvents are acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, methanol, ethanol, isopropyl alcohol, ethyl cellosolve, benzene, toluene, xylene, tetrahydrofuran, n-hexane, n-heptane, methylene chloride, chloroform, N,N-dimethylformamide, water and the like to which the solvents for use herein are not limited.

There is not limitation on infrared-absorbing materials useful in the present invention. Examples are as follows.

As the near infrared-absorbing materials, in addition to the diimmonium salt compound of the formula (1), one or both of fluorine-containing phthalocyanine compound and dithiol metal complex compound can preferably be contained in the coating solution. The coating solution preferably contains at least two species of diimmonium salt compound, fluorine-containing phthalocyanine compound and nickel complex compound. Preferred proportions of the near infrared-absorbing materials are 0.5 to 0.01 parts by weight of fluorine-containing phthalocyanine compound if used and 1 to 0 part by weight of nickel complex compound, per part by weight of the diimmonium salt compound.

Examples of the diimmonium salt compound of the formula (1) are N,N,N′, N′-tetrakis(p-di-n-butylaminophenyl)-p-benzoquinone-diimmonium.ditetrafluoroantimonate, N,N,N′,N′-tetrakis(p-diethylaminophenyl)-p-benzoquinone-diimmonium.ditetrafluoroantimonate, N,N,N′,N′-tetrakis(p-di-n-butylaminophenyl)-p-benzoquinone-diimmonium.diperchlorate, N,N,N′,N′-tetrakis(p-diethylaminophenyl)-p-benzoquinone-diimmonium.diperchlorate, N,N,N′,N′-tetrakis(p-diisopropylaminophenyl)-p-benzoquinone-diimmonium.ditetrafluorophosphate, N,N,N′,N′-tetrakis(p-n-propylaminophenyl)-p-benzoquinone-diimmonium.dinitrate and so on to which, however, useful diimmonium salt compounds are not limited. Some of them are commercially available. Among them, Kayasorb IRG-022, IRG-023 and the like (products of NIPPON KAYAKU Co., Ltd.) are suitably usable.

Useful fluorine-containing phthalocyanine compounds include, for example, Excolor IR1, IR2, IR3 and IR4 (products of NIPPON SHOKUBAI Co., Ltd.). Useful dithiol metal complex compounds include, for example, SIR-128, SIR-130, SIR-132 and SIR-159 (products of Mitsui Chemicals, Inc.).

The infrared absorption filter of the present invention preferably contains a UV-absorbing agent to enhance the resistance to light. Furthermore, in the present invention, the polymer for dispersing the infrared-absorbing material may be crosslinked with a crosslinking agent to impart weather-ability and resistance to solvents to the filter.

There is no limitation on transparent substrate films for use in the infrared absorption filter of the present invention. Useful transparent substrate films include, for example, stretched films formed of polyester resins, acrylic resins, cellulose resins, polyethylene resins, polypropylene resins, polyolefin resins, polyvinyl chloride resins, polycarbonate, phenolic resins, urethane resins or the like. From the standpoint of dispersion stability, environmental load and the like, polyester films are preferable.

In the infrared absorption filter having the infrared-absorbing layer on at least one side of the transparent polymer film, the transparent polymer film preferably has a total light transmittance of not lower than 89%, a haze of not higher than 1.6%, a coefficient of static friction of not higher than 0.6 and a coefficient of dynamic friction of not higher than 0.6.

The infrared absorption filter of the invention which is often used for display purposes has desirably a high total light transmittance, and desirably a low haze. However, if inert particles capable of imparting an uneven surface to the film are used in a reduced amount to increase the total light transmittance and to reduce the haze, generally the coefficient of friction is increased and the slidability is deteriorated, making it difficult to carry out the winding or like operation. If the total light transmittance, haze and coefficient of friction are within the ranges of the invention, it is possible to bring both the windability and the total light transmittance to the desired ranges.

In order to give the total light transmittance, haze and coefficient of friction in the above mentioned ranges, it is desirable to form a coating layer of 30 to 300
(4) Total Light Transmittance and Haze

Measured with a haze meter (product of Tokyo Denshoku Kogyo K.K., Model TC-H3DP) according to JIS K 7105

(5) Coefficient of Friction

The coefficient of static friction (μs) and the coefficient of dynamic friction (μd) were obtained according to JIS K 7125.

EXAMPLE 1

A base polyester to be used as a dispersing medium was prepared as follows. Charged into an autoclave equipped with a thermometer and a stirrer were:

	Dimethyl terephthalate	136	wt. Parts
	Dimethyl isophthalate	58	wt. Parts
	Ethylene glycol	96	wt. parts
	Tricyclodecane dimethanol	137	wt. parts
	Antimony trioxide	0.09	wt. part

These ingredients were heated to 170 to 220° C. for 180 minutes to undergo an ester exchange reaction. Then the temperature of the reaction system was elevated to 245° C. to continue the reaction under a pressure of 1 to 10 mmHg for 180 minutes, giving a polyester copolymer resin (A1). The polyester copolymer resin (A1) had an inherent viscosity of 0.4 dl/g and a glass transition temperature of 90° C. NMR analysis gave the following copolymer composition ratio:

	Acid components
	Terephthalic acid	71	mol %
	Isophthalic acid	29	mol %
	Alcohol components
	Ethylene glycol	28	mol %
	Tricyclodecane dimethanol	72	mol %

A flask was charged with the infrared-absorbing materials, the above-obtained resin and the solvents shown in Table 1 in the proportions indicated therein. The mixture was heated with stirring to dissolve the infrared-absorbing materials and the binder resin in the solvents. The resin solution was applied to a highly transparent polyester film substrate of 100 μm thickness having a slidable surface on one side and a smooth surface on the other side (product of Toyo Boseki K.K., “Cosmoshine A 4100; total light transmittance 90.9%, haze 0.7, coefficient of static friction (slidable surface/smooth surface: 0.58/>1), coefficient of dynamic friction (slidable surface/smooth surface: 0.42/>1)) using an applicator with a gap of 100 μm. The deposited layer was dried at a wind velocity of 0.4 m/s and a temperature of 90° C. in a hot air drier for 1 hour. The resulting coating film had a thickness of 25 μm.

The obtained infrared absorption filter had a color of dark gray when seen. The spectral property qf the filter is shown in FIG. 1. As shown in FIG. 1, the absorption was plotted as flat in the visible light region in the wavelength range of 400 to 650 nm. A difference was 4.8% between a maximum value and a minimum value of transmittance in the wavelength range of 450 to 650 nm, and the transmittance in the wavelength range was 69.4% at lowest. The sharp absorption was observed in the wavelength range of 700 nm or higher. The transmittance was 23.4% at highest in the wavelength range of 800 to 1100 nm.

The obtained filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours, and the spectral property was evaluated again with the results shown in FIG. 2. While a slight color change occurred, a difference of 9.8% was found between a maximum value and a minimum value of transmittance in the wavelength range of 450 to 650 nm and the transmittance in the wavelength range was 65.5% at lowest. The transmittance was 29.1% at highest in the wavelength range of 800 to 1100 nm and the filter retained the near-infrared-absorbing property.

Further, the obtained filter was left to stand in the atmosphere of a temperature of 80° C. for 1000 hours, and the spectral property was evaluated again with the results shown in FIG. 3. While a slight color change was brought about, a difference was 5.8% between a maximum value and a minimum value of transmittance in the wavelength range of 450 to 650 nm and the transmittance in the wavelength range was 67.2% at lowest. The transmittance was 21.0% at highest in the wavelength range of 800 to 1100 nm and the filter retained the near-infrared-absorbing property.

When disposed in front of a plasma display or the like, the obtained filter showed no change of color and increased the contrast, resulting in reduced level of near-infrared radiation.

TABLE 1
Ingredient	Material	Amount
Near-	Diimmonium salt compound,	3.2	wt. Parts
infrared-	Kyasorb IRG-022 manufactured
absorbing	by Nippon Kayaku Co., Ltd.
material	Fluorine-containing	0.5	wt. Part
	phthalocyanine compound,
	Excolor IR-1 manufactured by
	Nippon Shokubai Co., Ltd.
	Dithiol metal complex	1.6	wt. Parts
	compound, SIR-159
	manufactured by Mitsui
	Chemicals, Inc.
Binder resin	Polyester copolymer resin	440	wt. Parts
	(A1)
Solvent	Methyl ethyl ketone	490	wt. Parts
	Tetrahydrofuran	490	wt. Parts
	Toluene	490	wt. Parts

Comparative Example 1

Vylon RV 200 manufactured by Toyo Boseki K.K., (specific weight 1.26, glass transition temp. 67° C.) was used as a base polymer. A flask was charged with the infrared-absorbing materials, the binder resin and the solvents as shown in Table 2 in the proportions indicated therein. These ingredients were heated with stirring to dissolve the the infrared-absorbing materials and the binder resin in the solvents. The resin solution was applied to a highly transparent polyester film substrate of 100 μm thickness (product of Toyo Boseki K.K., “Cosmoshine A 4100”) using an applicator with a gap of 100 μm. The deposited layer was dried at a wind velocity of 0.4 m/s and a temperature of 90° C. in a hot air drier for 1 hour. The resulting coating film had a thickness of 25 μm. The obtained infrared absorption filter had a brown color when seen. As shown by the spectral property of the filter in FIG. 4, the absorption was plotted in a mountain-shaped form having a peak at about 550 nm in the visible light region in the wavelength range of 400 to 650 nm. A difference was 11.5% between a maximum value and a minimum value of transmittance in the wavelength range of 450 to 650 nm, and the transmittance in the wavelength range was 71.4% at lowest. The sharp absorption was observed in the wavelength range of 700 nm or higher. The transmittance was 44.0% at highest in the wavelength range of 800 to 1100 nm. The filter looked green when seen. When disposed in front of a plasma display of the like, the obtained filter lost a color balance, and turned greenish.

The obtained filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours, and the spectral property was evaluated again with the following results. A difference was increased from 11.5% to 28.6% between a maximum value and a minimum value of transmittance in the wavelength range of 450 to 650 nm and the transmittance in the wavelength range was 54% at lowest. The transmittance was increased to 49.0% at highest in the wavelength range of 800 to 1100 nm. The filter was deep green when seen. The spectral property is shown in FIG. 5. When disposed in front of a plasma display or the like, the obtained filter lost a color balance, and turned greenish.

Further, the obtained filter was left to stand in the atmosphere of a temperature of 80° C. for 1000 hours, and the spectral property was evaluated again with the following results. A difference rose from 11.5% to 20.3% between a maximum value and a minimum value of transmittance in the wavelength range of 450 to 650 nm and the transmittance in the wavelength range was 61.8% at lowest. The transmittance was increased to 47.2% at highest in the wavelength range of 800 to 1100 nm. The filter was deep green when seen. The spectral property of the filter is shown in FIG. 6. When disposed in front of a plasma display or the like, the obtained filter lost a color balance, and turned greenish.

TABLE 2
Ingredient	Material	Amount
Near-	Diimmonium salt compound,	3.2	wt. parts
infrared-	Kyasorb IRG-022 manufactured
absorbing	by Nippon Kayaku Co., Ltd.
material
Binder resin	Vylon RV 200 manufactured by	440	wt. parts
	Toyo Boseki K.K.
Solvent	Methyl ethyl ketone	490	wt. parts
	Tetrahydrofuran	490	wt. parts
	Toluene	490	wt. parts

Comparative Example 2

Vylon RV 200 (product of Toyo Boseki K.K., specific weight 1.26, glass transition temp. 67° C.) was used as a base polymer. A flask was charged with the infrared-absorbing materials, the binder resin and the solvents as shown in Table 3 in the proportions indicated therein. These ingredients were heated with stirring to dissolve the infrared-absorbing materials and the binder resin in the solvents. The resin solution was applied to a highly transparent polyester film substrate of 100 μm thickness (product of Toyo Boseki K.K., “Cosmoshine A 4100”) using an applicator with a gap of 100 μm. The deposited layer was dried at a wind velocity of 0.4 m/s and a temperature of 90° C. in a hot air drier for 1 hour. The resulting coating film had a thickness of 25 μm.

The obtained infrared absorption filter was dark gray when seen. The spectral property of the filter was substantially the same as in Example 1. The absorption was plotted as flat in the visible light region in the wavelength range of 400 to 650 nm. The sharp absorption was observed at 700 nm or more.

The obtained filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours, and the spectral property was evaluated again with the results shown in FIG. 7. A difference was increased from 4.8% to 27.4% between a maximum value and a minimum value of transmittance in the wavelength range of 450 to 650 nm, and the transmittance in the wavelength range was 44.0% at lowest. The transmittance was increased to 47.2% at highest in the wavelength range of 800 to 1100 nm. The filter looked green when seen. When disposed in front of a plasma display or the like, the obtained filter lost a color balance, and turned greenish.

Further the obtained filter was left to stand in the atmosphere of a temperature of 80° C. for 1000 hours, and the spectral property was evaluated again with the results shown in FIG. 8. A difference was increased from 4.8% to 16.6% between a maximum value and a minimum value of transmittance in the wavelength range of 450 to 650 nm and the transmittance in the wavelength range was 56.3% at lowest. The transmittance was increased to 30.2% at highest in the wavelength range of 800 to 1100 nm. The filter looked green when seen. When disposed in front of a plasma display or the like, the obtained filter looked green.

TABLE 3
Ingredient	Material	Amount
Near-	Diimmonium salt compound,	3.2	wt. parts
infrared-	Kyasorb IRG-022 manufactured
absorbing	by Nippon Kayaku Co., Ltd.
material	Fluorine-containing	0.5	wt. part
	phthalocyanine compound,
	Excolor IR-1 manufactured by
	Nippon Shokubai Co., Ltd.
	Dithiol metal complex	1.6	wt. parts
	compound, SIR-159
	manufactured by Mitsui
	Chemcials, Inc.
Binder resin	Vylon RV 200 manufactured by	440	wt. parts
	Toyo Boseki K.K.
Solvent	Methyl ethyl ketone	490	wt. parts
	Tetrahydrofuran	490	wt. parts
	Toluene	490	wt. parts

EXAMPLE 2

A coating solution was prepared using the polyester copolymer resin (A1) described in Example 1 together with the other ingredients shown in Table 1 in the proportions indicated therein. The coating solution thus obtained was applied to a highly transparent polyester film substrate of 100 μm thickness (product of Toyo Boseki K.K., “Cosmoshine A 4300”, total transmittance 90.9%, haze 0.7, coefficient of static friction (both surfaces) 0.58, coefficient of dynamic friction (both surfaces) 0.42) by a gravure roll. The deposited layer was dried for 1 minute by feeding hot air at a wind velocity of 5 m/s and a temperature of 130° C. and then the filter was wound into a roll. The resulting coating layer had a thickness of 8.0 pm. The amount of residual solvents in the coating layer was 4.1 wt %. The filter had a high slidability and showed a good roll appearance.

The obtained infrared absorption filter looked dark gray when seen. The spectral property of the filter is shown in FIG. 9. As shown in FIG. 9, the absorption was plotted as flat in the visible light region in the wavelength range of 400 to 650 nm. The sharp absorption was observed at a wavelength of 700 nm or more.

The obtained filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours, and the spectral property was evaluated again with the results shown in FIG. 10. The filter showed no great change in the spectral curve and exhibited stable performance.

Comparative Example 3

The coating solution used in Example 1 was applied to a highly transparent polyester film substrate (product of Toyo Boseki K.K., “Cosmoshine A 4300”) by a gravure roll. The deposited layer was dried for 1 minute by feeding hot air at a wind velocity of 5 m/s and a temperature of 120° C. The coating layer had a thickness of 11 μm. The amount of residual solvents in the coating layer was 6.5 wt. %. The filter looked dark gray when seen. The spectral property of the filter is shown in FIG. 11. As shown in FIG. 11, the absorption was plotted as flat in the visible light region in the wavelength range of 450 to 650 nm. The sharp absorption was observed at a wavelength of 700 nm or more.

The obtained filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours, and the spectral property was evaluated again with the results shown in FIG. 12. As indicated in FIG. 12, the absorption in the near-infrared region lowered and the color of the filter turned yellowish green.

EXAMPLE 3

In the transparent polyester film having the infrared-absorbing layer as obtained in Example 2, a hard coat-treated layer (HC) was formed on the surface of the side opposed to the infrared-absorbing layer. Used as a hard coat material was a UV-curable resin composition comprising 100 parts of an epoxy acrylic resin and 4 parts of benzophenone. The hard coat-treated layer was formed by a bar coat method. Then, preliminary drying was conducted at 80° C. for 5 minutes and the layer was cured by UV radiation with 500 mJ/cm². The cured hard coat-treated layer (HC) had a thickness of 5 μm.

Copper foil of 9 μm thickness was bonding to the surface of infrared-absorbing layer with a UV-curing adhesive, the bonded copper foil was patterned with photoresist and etched to give a an electromagnetic wave shielding layer. The copper foil had lines of 15 μm width, a pitch of 115 μm and an aperture ration of 75%.

FIG. 13 shows the spectral property of the filter having, as described above, the hard coat-treated layer on one side of the transparent polyester film substrate, and the infrared-absorbing layer and the electromagnetic wave shielding layer superposed in this order on the other side thereof. As shown in FIG. 13, it was found that the filter can absorb near-infrared rays, has a gray color and exhibits a high visible light transmission while absorbing an electromagnetic wave.

The obtained filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours, and the spectral property was evaluated again with the following results. Although a little changed in color, the filter maintained the near-infrared absorbing property. When disposed in front of a plasma display or the like, the obtained filter did not undergo change of color and increased the contrast, resulting in the decrease in radiation of near-infrared beams and in radiation of electromagnetic wave.

EXAMPLE 4

In the transparent polyester film having an infrared-absorbing layer as obtained in Example 2, a hard coat-treated layer (HC) was formed on the surface of the side opposed to the infrared-absorbing layer. Used as a hard coat material was a UV-curing resin composition comprising 100 parts of an epoxy acrylic resin and 4 parts of benzophenone. The hard coat-treated layer was formed by a bar coat method. Then, preliminary drying was conducted at 80° C. for 5 minutes and the layer was cured by UV radiation with 500 mJ/cm². The cured hard coat-treated layer (HC) had a thickness of 5 μm.

A thin film of tin oxide with 380 Å thickness was formed on the infrared-absorbing layer by a high-frequency magnetron sputtering device. Then a thin film of silver with 200 Å thickness was laminated on said thin film by a DC magnetron sputtering device. Further a thin film of tin oxide with 410 Å thickness was laminated thereon to form a electromagnetic wave shielding layer. The electromagnetic wave shielding layer had a surface resistance value of 4 Ω/□. FIG. 14 shows the spectral property of the filter having, as described above, the hard coat-treated layer on one side of the transparent polyester film substrate, and the infrared-absorbing layer and the electromagnetic wave shielding layer laminated in this order on the other side thereof. As shown in FIG. 14, the filter can absorb near-infrared rays, has a gray color, and exhibits a high visible light transmission while absorbing the electromagnetic wave.

The obtained filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours, and the spectral property was evaluated again with the following results. Although a little changed in color, the filter maintained the near-infrared absorbing property. When disposed in front of a plasma display or the like, the obtained filter did not undergo change of color and increased the contrast, resulting in the decrease in radiation of near-infrared beams and in radiation of electromagnetic wave.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the spectral property of the infrared absorption filter prepared in Example 1.

FIG. 2 shows the spectral property of the infrared absorption filter prepared in Example 1 after the filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours.

FIG. 3 shows the spectral property of the infrared absorption filter prepared in Example 1 after the filter was left to stand in the atmosphere of a temperature of 80° C. for 1000 hours.

FIG. 4 shows the spectral property of the infrared absorption filter prepared in Comparative Example 1.

FIG. 5 shows the spectral property of the infrared absorption filter prepared in Comparative Example 1 after the filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours.

FIG. 6 shows the spectral property of the infrared absorption filter prepared in Comparative Example 1 after the filter was left to stand in the atmosphere of a temperature of 80° C. for 1000 hours.

FIG. 7 shows the spectral property of the infrared absorption filter prepared in Comparative Example 2 after the filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours.

FIG. 8 shows the spectral property of thy infrared absorption filter prepared in Comparative Example 2 after the filter was left to stand in the atmosphere of a temperature of 80° C. for 1000 hours.

FIG. 9 shows the spectral property of the infrared absorption filter prepared in Example 2.

FIG. 10 shows the spectral property of the infrared absorption filter prepared in Example 2 after the filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours.

FIG. 11 shows the spectral property of the infrared absorption filter prepared in Comparative Example 3.

FIG. 12 shows the spectral property of the infrared absorption filter prepared in Comparative Example 3 after the filter was left to stand in the atmosphere of a temperature of 60° C. and a humidity of 95% for 1000 hours.

FIG. 13 shows the spectral property of the infrared absorption filter prepared in Example 3.

FIG. 14 shows the spectral property of the infrared absorption filter prepared in Example 4.

EFFECTS OF THE INVENTION

The infrared absorption filter of the present invention has broad absorption in the near-infrared region, shows a high visible light transmission and does not markedly absorb a specific light in the visible light wavelengths. When used for a plasma display or the like, the filter can absorb the unwanted infrared radiation emitted from the display, thereby making it possible to prevent erroneous operational of a remote control using infrared radiation. The infrared absorption filter of the present invention is gray in color so that it is unlikely to cause color change when used for a video camera, display or the like. Further the filter of the invention has such a high environmental stability that the filter can maintain said properties in an environment of a high temperature and a high humidity.

Claims

1. An infrared absorption filter which has a transmittance of not higher than 30% in the near-infrared region in the wavelength range of 800 to 1100 nm;

a difference of 10% or less between a maximum value and a minimum value of transmittance in the visible light region in the wavelength range of 450 to 650 nm; and

a transmittance of not lower than 50% at a wavelength of 550 nm,

said filter, after being left to stand in the air atmosphere at a temperature of 60° C. and a humidity of 95% for 1000 hours, having

a transmittance of not higher than 30% in the near-infrared region in the wavelength range of 800 to 1100 nm, and

a difference of 10% or less between a maximum value and a minimum value of transmittance in the visible light region in the wavelength range of 450 to 650 nm,

said filter having an infrared-absorbing layer on a transparent substrate,

the infrared-absorbing layer being composed of a coloring matter, dye or pigment absorbing infrared radiation and a polymer serving as a dispersing medium and

the transparent substrate having a total light transmittance of not lower than 89%, a haze of not higher than 1.6%, a coefficient of static friction of not higher than 0.6 and a coefficient of dynamic friction of not higher than 0.6.

2. The infrared absorption filter according to claim 1, wherein after being left to stand in the air atmosphere at a temperature of 80° C. for 1000 hours, the filter has a transmittance of not higher than 30% in the near-infrared region in the wavelength of 800 to 1100 nm and has a difference of 10% or less between a maximum value and a minimum value of transmittance in the visible light region in the wavelength of 450 to 650 nm.

3. The infrared absorption filter according to claim 1, wherein the amount of a solvent remaining in the infrared-absorbing layer is 5.0 wt % or less.

4. The infrared absorption filter according to claim 1, wherein the transparent substrate is a polyester film.

5. The infrared absorption filter according to claim 1, wherein the polymer constituting the infrared-absorbing layer has a glass transition temperature of not lower than 80° C.

6. The infrared absorption filter according to claim 5, wherein the polymer constituting the infrared-absorbing layer is a polyester resin.

7. The infrared absorption filter according to claim 1, wherein the filter has an electroconductive layer of metal mesh having an aperture ratio of not less than 50% on the same side as the infrared-absorbing layer of the filter or on the opposed side thereof.

8. The infrared absorption filter according to claim 1, wherein the filter has a transparent electroconductive layer on the same side as the infrared-absorbing layer of the filter or on the opposed side thereof.

9. The infrared absorption filter according to claim 8, wherein the transparent electroconductive layer is formed of a metal oxide.

10. The infrared absorption filter according to claim 8, wherein the transparent electroconductive layer has a repeatedly laminated structure in which at least three layers are laminated in the order of metal oxide/metal/metal oxide.

11. The infrared absorption filter according to claim 10, wherein the constituent metal layer of the transparent electroconductive layer is formed of silver, gold or a compound containing any of them.

12. The infrared absorption filter according to claim 1, wherein a hard coat-treated layer is formed as an outermost layer of the filter.

13. The infrared absorption filter according to claim 1, wherein an antireflection layer is formed as an outermost layer of the filter.

14. The infrared absorption filter according to claim 1, wherein an antiglare-treated layer is formed as an outermost layer of the filter.

15. The infrared absorption filter according to claim 1, wherein the filter is disposed in front of a plasma display.

16. An infrared absorption filter comprising a transparent substrate and an infrared-absorbing layer formed thereon,

the filter being prepared by coating the transparent substrate with a coating solution comprising an infrared-absorbing material, a binder resin and a solvent,

the binder resin being selected from polyester resins, acrylic resins, polyamide resins, polyurethane resins, polyolefin resins and polycarbonate resins, and

the amount of the solvent remaining in the infrared-absorbing layer being 5.0 wt. % or less.

17. The infrared absorption filter according to claim 16, wherein the binder resin has a glass transition temperature of not lower than 80° C.

18. The infrared absorption filter according to claim 16, wherein the binder resin is a polyester resin.

19. The infrared absorption filter according to claim 16, wherein the filter has an electroconductive layer of metal mesh having an aperture ratio of not less than 50% on the same side as the infrared-absorbing layer of the filter or on the opposed side thereof.

20. The infrared absorption filter according to claim 16, wherein the filter has a transparent electroconductive layer on the same side as the infrared-absorbing layer of the filter or on the opposed side thereof.

21. The infrared absorption filter according to claim 20, wherein the transparent electroconductive layer is formed of a metal oxide.

22. The infrared absorption filter according to claim 20, wherein the transparent electroconductive layer has a repeatedly laminated structure in which at least three layers are laminated in the order of metal oxide/metal/metal oxide.

23. The infrared absorption filter according to claim 22, wherein the constituent metal layer of the transparent electroconductive layer is formed of silver, gold or a compound containing any of them.

24. The infrared absorption filter according to claim 16, wherein a hard coat-treated layer is formed as an outermost layer of the filter.

25. The infrared absorption filter according to claim 16, wherein an antireflection layer is formed as an outermost layer of the filter.

26. The infrared absorption filter according to claim 16, wherein an antiglare-treated layer is formed as an outermost layer of the filter.

27. The infrared absorption filter according to claim 16, wherein the filter is disposed in front of a plasma display.

28. The infrared absorption filter according to claim 16, wherein the filter has a transmittance of not higher than 30% in the near-infrared region in the wavelength range of 800 to 1100 nm, and

after being left to stand in the air atmosphere at a temperature of 60° C. and a humidity of 95% for 1000 hours, the filter has a transmittance of not higher than 30% in the near-infrared region in the wavelength range of 800 to 1100 nm.

29. The infrared absorption filter according to claim 28, wherein the filter has a difference of 10% or less between the maximum value and the minimum value of transmittance in the visible light region in the wavelength range of 450 to 650 nm and a transmittance of not lower than 50% at a wavelength of 550 nm, and

after being left to stand in the air atmosphere at a temperature of 60° C. and a humidity of 95% for 1000 hours, the filter has a difference of 10% or less between the maximum value and the minimum value of transmittance in the visible light region in the wavelength range of 450 to 650 nm.

30. The infrared absorption filter according to claim 16, wherein the filter has a transmittance of not higher than 30% in the near-infrared region in the wavelength range of 800 to 1100 nm, and

after being left to stand in the air atmosphere at a temperature of 80° C. for 1000 hours, the filter has a transmittance of not higher than 30% in the near-infrared region in the wavelength range of 800 to 1100 nm.

31. The infrared absorption filter according to claim 30, wherein the filter has a difference of 10% or less between the maximum value and the minimum value of transmittance in the visible light region in the wavelength range of 450 to 650 nm and a transmittance of not lower than 50% at a wavelength of 550 nm, and

after being left to stand in the air atmosphere at a temperature of 80° C. for 1000 hours, the filter has a difference of 10% or less between the maximum value and the minimum value or transmittance in the visible light region in the wavelength range of 450 to 650 nm.

32. The infrared absorption filter according to claim 16, wherein the infrared-absorbing material contains a dimmonium salt compound.

33. The infrared absorption filter according to claim 32, wherein the dimmonium salt compound is represented by the formula (1): ##STR00002##

34. The infrared absorption filter according to claim 16, wherein the infrared-absorbing material contains at least two species of dimmonium salt compound, fluorine-containing phthalocyanine compound and nickel complex compound.