JPH0770482A - Infrared cut-off film and forming material thereof - Google Patents

Abstract

PURPOSE:To provide a large-sized film and a film-forming material transparent to visible light and having excellent cut-off effect on IR rays and producible at a low cost without badly influencing on the environment. CONSTITUTION:A transparent film is produced from a film-forming material containing ITO powder (preferably having an action to cut-off IR rays having wavelength longer than a specific wavelength of <=1,000nm) in water and/or an alcohol together with a binder (metal alkoxide and/or organic resin).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared ray which is not an environmentally harmful organic solvent but water and / or alcohol as a powder dispersion medium and is applied, printed or sprayed, at low cost, with good mass productivity and easy enlargement of area. The present invention relates to a film forming material capable of forming a transparent film having a cutoff function and a film formed from the film forming material.

Therefore, the infrared cutoff material of the present invention is
It can be used as a means for preventing counterfeiting of cards, cash vouchers, etc., which have been occurring frequently in recent years, or as an infrared reflecting film which is highly effective in improving cooling and heating efficiency. Especially when applied to general windows of housings, roofing materials for solariums, wall materials, glass of automobiles, etc., the infrared cutoff effect of sunlight in summer brings about a significant power saving effect for cooling, and in winter, indoors. Effective for keeping warm.

[0003]

2. Description of the Related Art Conventionally known as a transparent film having an infrared cutoff function that is transparent (transmits) to light in the visible region and is reflective to light in the infrared region. (A) a thin film of tin-doped indium oxide (hereinafter abbreviated as ITO) formed on a glass substrate by physical vapor deposition, chemical vapor deposition, or sputtering, (b) phthalocyanine-based, anthraquinone-based, naphthoquinone-based,
Cyanine type, naphthalocyanine type, polymer condensed azo type,
Organic dye type near-infrared absorber such as pyrrole-based, or dithiol-based, mercaptonaphthol-based or other organometallic complex salt is formed into an ink using an organic solvent and an organic binder, and coated on a substrate, or a resin. For example, it is kneaded into a film to form a film, which is laminated on a substrate.

However, with respect to (a), since it is necessary to use an apparatus that requires high vacuum and precise atmosphere control, not only the cost becomes high, but also the size and shape of the film are limited. Moreover, there are problems such as poor mass productivity and poor versatility.

Regarding (b), although the problem of (a) is solved, it has a low light transmittance in the visible region, has a deep dark brown to dark blue coloring, and is mostly 690 ~ 1000 n
Since it has a limited near-infrared absorption of about m,
For example, when it is used for general windows of housings, roofing materials for solariums, wall materials, etc., the visibility inside and outside through the windows and glass is poor, the aesthetics due to the color tone are poor, and the effect of cooling and heating the room However, there are problems such as insufficient.

In view of these problems, (c) an organic binder (polyvinyl chloride, acrylic resin, etc.) having an infrared cut-off ability, SnO ₂ fine powder having a particle size of 0.02 to 0.2 μm and an organic solvent (ketone-based, aromatic) Recently, it has been proposed to form an infrared ray absorbing film by coating a base material with a paint prepared by adding a small amount of a dispersant (anionic surfactant) to the base material (JP 63-281837).

However, in order for this film to exhibit a sufficient infrared cutoff function, it is necessary to perform hot pressing with a film thickness of 12 μm or more. With such a thick film, the light transmittance for visible light is reduced to around 50-60%, which hinders transparency, and solvent regulation is becoming more stringent. There are many problems such as using a solvent.

As described above, at present, a transparent film having an infrared cutoff function that meets the market demand has not yet appeared.

[0009]

The object of the present invention is to (1)
A film that is highly transparent to visible light and that has an excellent infrared cutoff effect (2) is formed by using a water and / or alcohol film forming material (3) without using an organic solvent that is harmful to the environment. It is an object to provide a film forming material that can be easily formed into a large area at low cost and can be mass-produced with good efficiency, and a transparent infrared cutoff film formed from the film forming material.

[0010]

The present inventors have found that a particle dispersion system in which a powder of ITO (tin-doped indium oxide), which is an inorganic oxide semiconductor, is dispersed in a transparent matrix is optimal for achieving the above object. The inventors have found that and reached the present invention.

Here, the gist of the present invention is to provide an infrared cut-off film characterized by containing ITO powder and a binder soluble or dispersible in water and / or alcohol in water and / or alcohol. A forming material, and an infrared cutoff film formed from this infrared cutoff film forming material.

In a preferred embodiment, the binder is (1) S
Alkoxide of i, Al, Zr or Ti and / or its partial hydrolyzate, (2) an organic resin soluble or dispersible in water and / or alcohol, or (3) the above (1)
And a mixture of (2). In addition, the ITO powder is 1000 n
Infrared rays with wavelengths longer than m and longer than a certain wavelength are totally
It is preferable to have a characteristic of 90% or more cutoff. When such an ITO powder is used, there is little reduction in the infrared cutoff effect when combined with a binder, and infrared rays can be cut off over a wide wavelength range from the low wavelength side near the visible region of the near infrared region. it can.

ITO powder is a material developed as a transparent conductive powder, and is made into a paint by combining it with an appropriate binder.
It has been used so far as a material for forming a transparent conductive film.
However, the use of ITO powder focusing on the infrared cutoff function has never been attempted.

As a result of investigations by the present inventors, ITO powder has a high cutoff effect in the near infrared region, and a film formed by coating it with an aqueous and / or alcoholic coating is useful as an infrared cutoff film. I clarified that.

However, an inorganic oxide semiconductor other than ITO, such as antimony-doped tin oxide (abbreviated as ATO), is used.
, Aluminum-doped zinc oxide (AZO), etc. did not provide an infrared cutoff effect at a level suitable for practical use.

[ITO powder] It is preferable that the average primary particle diameter of the ITO powder is 0.2 μm or less, preferably 0.1 μm or less because transparency (transmission to visible light) is not impaired.

Therefore, the ITO powder is such a fine powder in applications requiring transparency such as an infrared cutoff film formed on a transparent substrate such as glass, a transparent film, and a transparent molded article. It is preferable. However, for applications where transparency is not required so much (eg, infrared cut-off materials for walls and roofs), ITO powder with a larger particle size can be used. The Sn doping amount in the ITO powder has a Sn / (Sn + In) molar ratio of 0.01 to 0.15, particularly 0.04 to 0.12.
It is preferably within the range.

The ITO powder is generally prepared by reacting an aqueous solution containing In and a small amount of a water-soluble salt of Sn with an alkali to coprecipitate a hydroxide of In and Sn, and use this coprecipitate as a raw material in the atmosphere. It is produced by heating and burning to convert it into an oxide. Instead of coprecipitate, it is also possible to use a hydroxide and / or oxide mixture of In and Sn as the raw material.
In the present invention, I is commercially available as the ITO powder or the conductive powder manufactured by the conventional method.
The TO powder can be used as it is.

However, the ITO powder produced by such a conventional method has excellent transparency in the visible region and good transparency, but the infrared cutoff effect is more than 1000 nm.
Most of them only cut off infrared rays in the wavelength region of 1200 nm or more, and the cutoff effect of infrared rays in the wavelength range of 1200 nm or less, particularly 1000 nm or less is often insufficient. Therefore, when such an ITO powder is dispersed in the resin matrix, it is not possible to cut off the infrared rays in the wavelength range close to the visible range, but even in this case, 1800 nm
Since infrared rays on the longer wavelength side can be cut off,
It is effective for applications such as anti-counterfeit ink for cards and ink for hidden barcodes.

In a preferred embodiment, as ITO powder,
Use the one that has the property of completely cutting off 90% or more of infrared rays on the longer wavelength side of a certain wavelength of 1000 nm or less (that is, the minimum cutoff wavelength is 1000 nm or less). Here, the minimum cutoff wavelength means the minimum wavelength at which the light cutoff rate is at least 90% in the infrared region or its vicinity (600 nm or more). This means that in the light transmission spectrum, the light transmittance is 10 in the long wavelength side direction.
It corresponds to the minimum wavelength in the wavelength region of not more than%. More preferably, the minimum cutoff wavelength of ITO powder is 700
Within the range of ~ 900 nm.

A preferred ITO powder having a minimum cut-off wavelength of 1000 nm or less is obtained by firing the raw material (hydroxide and / or oxide) in a pressurized inert gas or by firing in air. It can be manufactured by heat-treating the obtained ITO powder in a pressurized inert gas.
However, the manufacturing method is not limited to this, and an ITO powder manufactured by another method is also useful as long as the minimum cutoff wavelength is 1000 nm or less.

When the characteristics of such ITO powder were investigated, the color tone of the powder was found to be 0.220 to 0.295 as the x value on the xy chromaticity diagram.
The y-value was in the range of 0.235 to 0.325 and the lattice constant of the crystal was in the range of 10.110 to 10.160Å. Therefore, the preferable ITO powder used in the present invention can be specified also by examining this characteristic.

The raw material of this preferable ITO powder may be prepared in the same manner as in the conventional method. For example, the molar ratio of Sn / (Sn + In) is preferably 0.01 to 0.15, and particularly preferably 0.02 to 0.12.
An aqueous solution prepared by dissolving a water-soluble compound of In and Sn (eg, chloride, nitrate, etc.) in water is treated with an alkaline aqueous solution (eg, an aqueous solution of an alkali metal or ammonium hydroxide, carbonate, bicarbonate, etc.). By reacting, each water-soluble compound is hydrolyzed to precipitate an In—Sn coprecipitated hydroxide. It is preferable to proceed the reaction while dropping one aqueous solution into the other aqueous solution under stirring so that a fine precipitate is deposited at this point as much as possible.

The hydrous In-Sn coprecipitated mixed hydroxide thus obtained is used as it is, or an anhydrous mixed hydroxide obtained by heating and drying this to remove water, or further dehydration to at least partially Mixed (water) as oxide Use oxide as raw material. The heating temperature at this time may be 200 ° C. or lower, particularly 150 ° C. or lower for only drying, but higher temperature (eg, 200 to 900 ° C.) can be used for conversion to an oxide. The above-mentioned ITO powder is obtained by firing the obtained raw material in a pressurized inert gas atmosphere with oxygen blocked until it completely becomes an oxide. Alternatively, the above-mentioned preferable ITO powder can also be obtained by firing the raw material in the same manner as in the prior art, for example, to obtain an ITO powder, and then heat-treating this powder in a pressurized inert gas atmosphere.

The inert gas atmosphere during this firing or heat treatment (hereinafter collectively referred to as heat treatment) may be a rare gas such as argon or helium, a nitrogen gas, or a mixed gas thereof. The pressure condition of the inert gas atmosphere is 2 kgf / cm ² or more in total pressure at room temperature, especially 5 to 5.
It is preferably within the range of 60 kgf / cm ² .

When the pressure of the inert gas atmosphere is less than 2 kgf / cm ² , the infrared cutoff effect is about the same as that of the conventional ITO powder, and the improvement is hardly obtained, but the temperature is 80%.
At high temperature such as over 0 ℃, even if the pressure is normal pressure,
The above-mentioned preferable ITO powder may be obtained. Even if the pressure is increased to more than 60 kgf / cm ² , there is only a slight improvement in the effect, so no further pressurization is required in practice. The oxygen partial pressure in an inert gas atmosphere is 0.2 kgf / cm ² (1
It is preferably limited to 50 Torr) or less, particularly 0.02 kgf / cm ² (15 Torr) or less.

The heat treatment temperature is generally effective in the range of 350 to 1000 ° C, preferably in the range of 400 to 800 ° C. If the treatment temperature is 350 ° C. or lower, the effect of atomization is high, but the infrared cutoff effect is hardly improved. On the other hand, when the temperature is 1000 ° C. or higher, the particle size grows remarkably, which is not preferable when used in a field requiring transparency. Regarding the heat treatment time, it suffices that uniform heat treatment is achieved for the raw material or the ITO powder,
Generally 1 to 4 though it varies depending on the charged amount and temperature.
It is within the range of time. The temperature rising / falling rate is not particularly limited.

[Film Forming Material] The film forming material of the present invention is obtained by dispersing or dissolving ITO powder and a binder in water and / or alcohol.

As a medium for dispersing the ITO powder and dissolving or dispersing the binder, water and / or alcohol is used instead of an organic solvent harmful to the environment. Examples of alcohols suitable for the medium are methanol, ethanol, propanol, isopropanol, butanol, hexanol, cyclohexanol and the like, and one or more of these can be used. Also, a mixed solvent of water and alcohol can be used.

As the binder, any binder soluble or dispersible in water and / or alcohol as a medium can be used, but preferably (1) an alkoxide of Si, Al, Zr or Ti and / or a partial hydrolysis thereof. Degradation products, (2) organic resins soluble or dispersible in water and / or alcohols, and (3) mixtures thereof.

Examples of the alkoxide of (1) include Si, Al and Zr.
And methoxide of metal selected from Ti, ethoxide,
Examples thereof include propoxide, butoxide, and the isomers thereof (isopropoxide, sec-butoxide, t-butoxide, etc.), and one or more of these can be used. When these metal alkoxides are dissolved in water or alcohol and applied, they are converted into oxides by hydrolysis during the drying process to form a transparent film made of metal oxides. Therefore, it can be used as a binder for binding the ITO particles in the present invention.

Specific examples of suitable metal alkoxides include silicon tetraethoxide (ethyl silicate),
Aluminum triisopropoxide, zirconium tetrabutoxide, titanium tetraisopropoxide, and the like. A partial hydrolyzate of a metal alkoxide obtained by adding a small amount of water and / or an acid to a metal alkoxide to form a multimer can also be used instead of the metal alkoxide or in a mixture with the metal alkoxide.

Another binder that can be used in the present invention is
It is an organic resin capable of forming a transparent film soluble or dispersible in water and / or alcohol. This type of binder includes organic resins used in water-based or alcohol-based paints. In the case of an aqueous system, a water-soluble resin or a water-dispersible emulsion resin is used. Examples of such resins are water-soluble alkyd resins, polyvinyl alcohol, polybutyl alcohol, etc., or emulsion type water-dispersible resins such as acryl, acryl-styrene, vinyl acetate. In the case of an alcohol type, a resin soluble or dispersible in alcohol such as polyvinyl acetal such as polyvinyl butyral can also be used as a binder.

When the binder is a metal alkoxide, IT
It is possible to obtain a completely inorganic film in which O particles are dispersed in a metal oxide matrix. This film is particularly excellent in visible light transmittance, has a hard film, and is also excellent in heat resistance. On the other hand, when the binder is an organic resin, a film having excellent flexibility can be obtained. Therefore, the type of binder may be selected according to the type of substrate and the application for forming a transparent film having an infrared cutoff function.

For example, when the substrate is a plastic film, an organic resin is used as a binder to ensure flexibility even in a transparent film having an infrared cutoff function so as not to impair the flexibility of the substrate. Preferably. on the other hand,
When the substrate is glass and film hardness is required, it is preferable to use a metal alkoxide as a binder.

Further, the above organic resin and metal alkoxide can be used together as a binder. Thereby, when the binder is a metal alkoxide, flexibility can be imparted to the film having an infrared cutoff function which is excellent in transparency.

The composition of the film forming material of the present invention is ITO powder 10
It is preferable that the binder (the amount of the metal alkoxide as an oxide and the amount of the resin as a solid content) be 2 to 200 parts by weight based on 0 part by weight. The amount of water and / or alcohol as the dispersion medium may be such that a viscosity suitable for the application form such as coating, printing, spraying, dipping and the like can be obtained, but usually 10 parts by weight relative to 100 parts by weight of ITO powder. Within the range of up to 1000 parts by weight.

When the binder is a metal alkoxide and the dispersion medium is an alcohol, 1 part by weight or less of an acid or 100 parts by weight of a metal alkoxide is added to accelerate the hydrolysis of the alkoxide, if necessary. You may add water not more than a weight part. Further, when the binder is an organic resin, a small amount of a curing agent, a cross-linking agent, etc. may be added if necessary. As the additive contained in the transparent film forming material having the infrared cutoff function of the present invention, a pH adjusting agent,
Examples include defoaming agents and wetting agents.

[Infrared Cutoff Film] The film forming material having an infrared cutoff function of the present invention is applied to a substrate by an appropriate film forming means such as coating, printing, spraying or dipping, and then heated if necessary. When the dispersion medium is removed and dried, a transparent film having an infrared cutoff function can be formed. The drying temperature may be selected according to the type of medium and binder.

The infrared cutoff film thus formed has a structure of a particle dispersion system in which ITO powder is uniformly dispersed in a metal oxide or organic resin matrix. This infrared cutoff film exhibits infrared cutoff characteristics according to the characteristics of the ITO powder used, provided that the other conditions such as the matrix type and the amount of ITO powder blended are the same. If the ITO powders are the same, the infrared cutoff effect tends to increase as the ratio of the ITO powders to the matrix increases.

For example, when the minimum cutoff wavelength of the ITO powder used is 1000 nm or less, the infrared cutoff film of the present invention generally has a light transmittance of 80% or more for visible light and an infrared cutoff film for infrared rays. It shows a characteristic that it cuts off 80% or more of infrared rays on the longer wavelength side than a certain wavelength within the range of 850 to 1500 nm. If the minimum cutoff wavelength of the ITO powder used is greater than 1000 nm, the properties of the infrared cutoff film are inferior, and the wavelength at which 80% or more of the infrared cutoff begins is longer than 1800 nm.

The light transmittance (transparency) for visible light is I
The average primary particle size of TO powder is 0.2 μm or less, especially 0.1 μm
When the particle size is m or less, when the powder is uniformly dispersed in the primary particles in the medium, the scattering of light with respect to visible light is extremely suppressed, so that the transparency of 80% or more can be maintained. Therefore, infrared rays can be selectively cut off without impairing transparency.

The infrared cut-off film of the present invention can cut off infrared rays from the near-infrared region close to the visible region with high efficiency in spite of being able to produce a large-area one with low cost and mass productivity. It is possible to exhibit extremely excellent infrared cutoff characteristics and high transparency. Furthermore, the ITO powder was originally developed as a conductive powder, and for example, the infrared cutoff film of the present invention exhibits high conductivity in the surface resistance value range of 10 ² to 10 ⁸ Ω / □. Therefore, the infrared cutoff material of the present invention,
It also has the function of preventing static electricity and the adhesion of dust, and at the same time, it has the effect of not being easily soiled when used on glass or walls.

The infrared cutoff film forming material and the infrared cutoff film containing the ITO powder of the present invention are, for example, window glass, sunroof, optical fiber, prepaid card,
Sun visor, PET (polyethylene terephthalate)
It can be applied to products such as bottles, wrapping films, and eyeglasses to impart infrared reflection effect to the products.

For window glass, the infrared cutoff film forming material of the present invention is applied to the glass by an appropriate application means (eg, coating, spraying, dipping, etc.), and a transparent film containing ITO powder is applied to the glass. Can be formed on. In this way, the transparent film containing ITO powder provided on the surface of the window glass can reflect the infrared rays of the sun's rays in a wide wavelength range, and the cooling and heating efficiency of the room can be significantly improved.

For prepaid cards, I of the present invention
A film forming material containing TO powder is applied to a predetermined portion of the prepaid card to form an infrared cutoff film. By irradiating the prepaid card with infrared rays and inspecting for the presence or absence of reflected light, it is possible to determine whether the card is counterfeit.

As for the remaining sunroofs, optical fibers, sun visors, PET bottles, packaging films, and glasses, an ITO-containing transparent film having an infrared reflection effect is formed from a film-forming material containing ITO powder, as in the above window glass. Can be formed.

In addition to the above-mentioned uses, the ITO powder-containing film forming material of the present invention can be applied to other uses requiring infrared reflection. For example, when a transparent film containing ITO powder is formed on the transparent wall of glass or plastic in the storage, it is possible to prevent dew condensation on the outer surface of the storage and temperature rise in the storage. Even if the wall of the storage is opaque, IT
If the O powder-containing film is formed, it is possible to block infrared rays from the outside and prevent the temperature rise in the refrigerator and the deterioration of the stored article due to the temperature rise.

When applied to a greenhouse or greenhouse, the film forming material of the present invention is applied to the surface of a film or glass.
By forming the film containing the TO powder, it is possible to obtain the effect of promoting the growth of plants due to the heat retaining effect in the house.

The film forming material containing the ITO powder of the present invention can be applied to a textile product such as clothes and futon by spraying or spraying to form a film containing the ITO powder on the fiber surface. As a result, the far infrared rays radiated from the human body come to be reflected from the fibers, so that the heat retaining property is improved.

For a peep window of a roasting room, a microwave oven, a toaster, an oven, etc., the same method as the glass window is used.
A TO powder-containing film forming material can be applied. Similarly, in an electric heater using a glass heater, by forming a film containing ITO powder around the glass heater, the heat radiated from the electric resistor is efficiently reflected and the heating effect is enhanced. . According to the present invention, the above-mentioned functions can be more effectively exhibited than ever before.

[0052]

The present invention will be further described below with reference to Examples and Comparative Examples, but these do not limit the present invention. In the following examples and comparative examples, the average primary particle size of the powder is calculated from the measured value of the specific surface area (BET) by the following particle size formula: a (μm) = 6 / (ρ × B) [a: average particle Diameter, ρ: true specific gravity, B: specific surface area (m ² / g)]. Thus, it has been confirmed that the particle size obtained from the specific surface area is almost the same as the particle size directly observed by the transmission electron microscope. The specific surface area according to the BET method was measured using a Betasorb automatic surface area meter Model 4200 manufactured by Microtrac. In addition, the light transmission spectra of the powder and film can be measured using the self-recording spectrophotometer U-4000 with an integrating sphere.
It was measured by a diffuse reflection method using a mold (manufactured by Hitachi, Ltd.).

A. Production of powder (Production Example 1) InC1 ₃ aqueous solution 1.8 L (containing 600 g of In metal) and 60
% SnC1 ₄ aqueous solution (22.92 g (containing 6.27 g of Sn metal)) was added dropwise to an aqueous solution of NH ₄ HCO ₃ 3100 g / 12 L with stirring at 70 ° C to a final pH of 8.5. In-
Sn coprecipitated hydroxide was deposited. Next, after allowing the precipitate to settle by allowing it to stand, remove the supernatant liquid, add ion-exchanged water, and perform standing and sedimentation and removal of the supernatant liquid 6 times (the amount of water added is 10 L each time). ) By repeating the procedure, the precipitate was sufficiently washed with water and then filtered by suction filtration to obtain a hydrous hydroxide precipitate. The precipitate was dried overnight at 110 ° C.

250 g of this dried coprecipitated hydroxide
Place in a 250 mm half-split quartz boat, inner diameter 70 mm, length 700
It was fired in a pressurized nitrogen gas atmosphere using a closed pressure tubular furnace made of mm Incoloy 800 tube. That is, after putting the boat in a tubular furnace, the system was evacuated to a vacuum, pressurized with nitrogen gas to a pressure of 15 kgf / cm ² , heated up to 600 ° C. in a sealed state, and kept at this temperature for 3 hours. It was fired to obtain ITO powder.

The average primary particle size of the obtained ITO powder is 0.
The light transmission spectrum was 94% or more, and an excellent infrared cut-off effect of 94% or more was observed on the whole surface at 750 nm or more. Its minimum cutoff wavelength was 700 nm.

(Production Example 2) For comparison, as an example of a conductive powder other than ITO, antimony-doped tin oxide (ATO) was used.
The powder was prepared as follows. SnC1 ₄ aqueous solution 1.8 L
(Containing 600 g of Sn metal) and 0.2 L of SbCl ₃ aqueous solution (Sb metal 80
(containing g) is added dropwise to an aqueous solution of 900 g / 12 L of NaOH while heating at 90 ° C with stirring to give a final pH of 7
Then, Sn-Sb coprecipitated hydroxide was deposited. Next, after allowing the precipitate to settle by allowing it to stand, remove the supernatant liquid, add ion-exchanged water, and perform standing and sedimentation and removal of the supernatant liquid 6 times (the amount of water added is 10 L each time). By repeatedly washing the precipitate with water by repeating, the precipitate is filtered off by suction filtration,
A hydrous hydroxide precipitate was obtained. The precipitate was dried overnight at 110 ° C.

Next, firing was performed under the same conditions as in Production Example 1 to obtain ATO powder. The average primary particle size of this powder is 0.
029 μm, optical transmission spectrum is 33% at 1200 nm
As mentioned above, it was confirmed that 96% or more of the infrared rays were finally cut off over 1240 nm. Its minimum cutoff wavelength was 1240 nm.

B. Formation of Infrared Cutoff Film (Example 1) 10 g of the ITO powder obtained in Production Example 1 was dispersed in 20 g of ethyl alcohol for 60 minutes using a paint shaker (25 g of glass beads). Next, 10 g of ethyl silicate as a binder was added to this powder dispersion, 0.4 g of 1N hydrochloric acid was added to accelerate hydrolysis of this alkoxide, and 2 g of pure water was added.
Was added, and the mixture was shaken for an additional 150 minutes, and the beads were removed to prepare a film forming agent. Next, this film forming agent was applied to a polyethylene terephthalate (PET) film using a bar coater so that the dry film thickness was 1 μm, and the temperature was 100 ° C.
After drying in, the characteristics of the obtained transparent film were examined.

(Example 2) 10 g of the ITO powder obtained in Production Example 1
Was dispersed in 90 g of isopropyl alcohol for 60 minutes using a paint shaker (25 g of glass beads).
Next, ethyl silicate as a binder was added to this powder dispersion.
10 g and 3.5 g of titanium tetrapropoxide were added, and the mixture was further shaken for 150 minutes, and the beads were removed to prepare a film forming agent. Then, a transparent film was formed in the same manner as in Example 1.

(Example 3) 10 g of the ITO powder obtained in Production Example 1
Was dispersed in 10 g of pure water for 120 minutes using a paint shaker (25 g of glass beads). Next, a water-soluble alkyd resin (solid content 50
%) 7 g and cobalt naphthenate 0.3 g as a curing agent were added, and the mixture was further shaken for 150 minutes, and the beads were removed to prepare a film forming agent. Then, a transparent film was formed in the same manner as in Example 1.

Example 4 10 g of ITO powder obtained in Production Example 1
Was dispersed in 10 g of pure water for 120 minutes using a paint shaker (25 g of glass beads). Next, an emulsion type acrylic resin as a binder was added to the powder dispersion.
(Solid content 40%) 5 g was added, and the mixture was further shaken for 90 minutes, and the beads were removed to prepare a film forming agent. Then, a transparent film was formed in the same manner as in Example 1.

(Example 5) 10 g of the ITO powder obtained in Production Example 1
Was dispersed in 20 g of ethyl alcohol for 60 minutes using a paint shaker (25 g of glass beads). next,
To this powder dispersion, 10 g of ethyl silicate as a binder and 0.5 g of polybutyl alcohol resin dissolved in 10 g of ethyl alcohol were added, and further shaken for 90 minutes to remove the beads and prepare a film forming agent. Then, a transparent film was formed in the same manner as in Example 1.

Comparative Example 1 ATO powder 10 obtained in Production Example 2
g, it was dispersed in 20 g of ethyl alcohol for 60 minutes using a paint shaker (glass beads: 25 g). next,
10 g of ethyl silicate as a binder in this powder dispersion,
1N hydrochloric acid 0.4 to accelerate the hydrolysis of this alkoxide
g and 2 g of pure water were added, and the mixture was further shaken for 150 minutes to remove beads and prepare a film forming agent. Then, a transparent film was formed in the same manner as in Example 1.

The light transmission spectra of the films obtained in the above Examples and Comparative Examples are summarized in FIG. The ITO powder-containing films obtained in Examples 1 to 5 all showed excellent light transmittance of around 80% or more in the visible region, and were longer than a certain wavelength within the range of 800 to 1100 nm in the infrared region. It has an excellent infrared cutoff function that can cut off 80% or more of infrared rays on the wavelength side. As in Examples 1 and 2, the completely inorganic transparent film in which the matrix is formed of a metal alkoxide has a higher infrared cutoff effect and cuts off infrared light from a lower wavelength side, and from a portion close to the visible region. It has a very excellent cutoff effect that can cut off 80% or more of infrared rays over the entire surface.

In the ATO-containing film of Comparative Example 1, even at 1200 nm, the infrared cutoff ratio was only a little over 30%, and the infrared cutoff effect was very poor. In this case, the infrared cutoff rate exceeds 80% at a wavelength of 1630 nm or more, which is not practical as an infrared cutoff material.

[0066]

As described above, the infrared cutoff film of the present invention has (1) high transparency to visible light and a high cutoff effect to infrared rays, and (2)
It is harmful to the environment, and it is possible to form a film with water and / or alcohol without using an organic solvent. (3) Low cost, large area is easy, and mass productivity is excellent. Therefore, it can be easily applied to general windows for housings, roofing materials for solariums, wall materials for automobiles, or glass for automobiles, etc., thereby almost completely reflecting the infrared rays of summer sunlight, and cooling etc. Help to save a lot of electricity. In winter, it also helps improve the heat insulation effect inside the room. Further, since the infrared cutoff film of the present invention can be detected by irradiation of infrared rays, it can be used as a forgery preventing means for cards and the like.

[Brief description of drawings]

FIG. 1 is light transmission spectra of films obtained in Examples and Comparative Examples.

[Procedure amendment]

[Submission date] July 4, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

The composition of the film forming material of the present invention is ITO powder 1
The binder (the amount of metal alkoxide as an oxide, the amount of resin as a solid content) is 1 to 2000 parts by weight with respect to 00 parts by weight.
Parts by weight, preferably 10 to 400 parts by weight, more preferably
Is in the range of 20 to 200 parts by weight. The amount of water and / or alcohol as the dispersion medium may be an amount such that the viscosity suitable for the application form such as coating, printing, spraying, dipping and the like can be obtained, but it is usually 5 per 100 parts by weight of the ITO powder. ~
It is in the range of 5000 parts by weight, preferably 10 to 500 parts by weight .

Claims (4)

[Claims] 1. An infrared cut-off film forming material comprising tin-doped indium oxide powder and a binder soluble or dispersible in water and / or alcohol in water and / or alcohol. 2. The binder is (1) an alkoxide of Si, Al, Zr or Ti and / or a partial hydrolyzate thereof,
2. The infrared cutoff film formation according to claim 1, which is (2) an organic resin soluble or dispersible in water and / or alcohol, or (3) a mixture of (1) and (2). Material. 3. The tin-doped indium oxide powder is 1000 n
Infrared rays with wavelengths longer than m and longer than a certain wavelength are totally
Claim 1 or 2 which cuts off 90% or more.
Infrared cut-off film forming material described. 4. An infrared cutoff film formed from the infrared cutoff film forming material according to claim 1.