JPH10120946A - Shielding material of infrared ray - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a shielding material of infrared rays, capable of forming a indium oxide membrane containing tin and excellent in transparency and shielding properties of the infrared rays by including a fine powder of tin- containing indium oxide and obtained by a specific method, a coating binder and a solvent. SOLUTION: This shielding material of infrared rays comprises (A) indium oxide fine powder containing tin obtained by heat treating the hydrate of the tin oxide and indium oxide obtained by adding an aqueous alkali solution (preferably aqueous ammonia or an aqueous solution of an ammonium salt) to a solution of a tin salt and an indium salt while keeping the temperature <=30 deg.C, under an inert gas atmosphere or a reductive gas atmosphere, (B) a coating material binder and (C) a solvent. Preferably, the shielding material is obtained by using the tin and the indium so that the weight ratio of SnO2 :In2 O3 may be (4:26) to (15:85), adding the aqueous alkali solution thereto so that the pH may be 5-9 for 30min to 12hr, and heating the resultant hydrate under the before atmosphere at 300-1,000 deg.C. The content of the component A is preferably 40-95wt.% in the solid of the objective material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an infrared shielding material suitable for forming an infrared shielding film by a coating method.

[0002]

2. Description of the Related Art Conventionally, conductive materials such as tin oxide, zinc oxide and tin-containing indium oxide (ITO) have been used because of their conductivity, transparent electrodes such as solar cells and liquid crystal displays, or transparent conductive films such as electroluminescent displays and touch panels. While it is widely used as a film, it is also used as a heat ray reflection (infrared ray shielding) film utilizing selective translucency which is another function. Specifically, it is deposited on the bulbs of incandescent lamps and halogen lamps, or on the surface of the lamp housing, to block the strong heat rays from each light source or to increase the heat ray radiation. In winter, it prevents radiation loss of indoor warm air, and in summer, it prevents solar heat rays and releases cold indoor air to achieve energy saving effects. Among the thin films made of these conductive materials, ITO films have high reflectivity in the infrared region in addition to excellent transparency in the visible region,
It can be said that it is most suitable for this use. Such an ITO
The film is formed by a sputtering method, a vacuum evaporation method, a coating method, or the like. Among them, the coating method can be processed into a large area or a complicated shape which is difficult by a sputtering method or a vacuum evaporation method, and is advantageous in cost. As a coating method, a so-called spray pyrolysis method using an inorganic or organic indium salt is generally used, but with the development of fine particle manufacturing technology in recent years, a method of applying this using fine powder has a film forming temperature. Has been attracted attention because it is possible to reduce the amount of material used, increase the degree of freedom in selecting the material of the base material, and reduce the cost.

In the case of using ITO fine powder, forming it into a paint and applying it on a substrate to form a thin film, first, its dispersibility is important. If this is insufficient, the transmittance in the visible part and the infrared Reflectivity is low. In order to improve the dispersibility, it is essential that the fine ITO powder is fine, the number of coarse particles is small, and the width of the particle size distribution is narrow.

[0004] In order to improve the reflectivity in the infrared region, it is necessary to increase the conductivity of the film by using the relationship between the plasma wavelength and the carrier concentration based on Drude's classical dispersion theory (the absorption by free electrons is maximized). The plasma wavelength shifts to a shorter wavelength side as the carrier concentration increases, that is, as the conductivity increases, and light having a wavelength longer than that wavelength is reflected.)

Therefore, in the case of an infrared shielding material using fine ITO powder, improving the conductivity of the fine ITO powder itself leads to an increase in the reflectance in the infrared region. I
As a means for improving the conductivity of the TO fine powder, it is known to perform heating and deoxidation treatment in an inert gas atmosphere or a reducing gas atmosphere (JP-A-1-1000).
No. 23).

Hitherto, regarding the infrared shielding material using the fine ITO powder, JP-A-7-70363, JP-A-7-70445, JP-A-7-70481, and JP-A-7-70481.
Japanese Patent Application Laid-Open No. 70482/1994 or Japanese Patent Application Laid-Open No. H08-41441 has been proposed, all of which use ITO fine powder used as a conventional conductive coating material as a raw material, and then perform treatment in a pressurized inert gas atmosphere. Since the processing is performed, the following problems are included. That is, in these infrared shielding materials, those obtained by co-precipitating indium and tin hydroxide by reacting an aqueous solution of a compound of indium and tin with an aqueous alkali solution, or those obtained by heat-treating the co-precipitated hydroxide Is further treated in a pressurized inert gas atmosphere, or by using ITO fine powder obtained by a reduction treatment with methanol-containing nitrogen gas or the like. In this case, coarse particles are likely to be generated, and the particle size distribution width must be widened, and it is difficult to disperse when forming a coating, so that the resulting film is not enough for the above applications, both in transparency and infrared shielding properties It is.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an infrared shielding material capable of solving the above-mentioned problems and forming a tin-containing indium oxide (ITO) film having excellent transparency and infrared shielding properties. It is in.

[0008]

According to the present invention, a tin salt and indium oxide hydrate obtained by adding an aqueous alkali solution to a tin salt and indium salt solution while maintaining the temperature at 30 ° C. or lower is made inert. The present invention relates to an infrared shielding material comprising a tin-containing indium oxide fine powder obtained by heat treatment in a gas atmosphere or a reducing gas atmosphere, a paint binder, and a solvent.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The fine ITO powder used in the present invention is a hydrate of tin oxide and indium oxide obtained by adding an aqueous alkali solution to a tin salt and indium salt solution while maintaining the temperature at 30 ° C. or less. It is obtained by subjecting the product to a heat treatment in an inert gas atmosphere or a reducing gas atmosphere. The tin salt and the indium salt used may be any water-soluble ones, and examples thereof include tin chloride, tin sulfate, tin nitrate, indium chloride, indium sulfate, indium nitrate, and the like. Any of tin salts may be used. After dissolving such tin salt and indium salt in water and adding a water-soluble organic solvent such as alcohol and acetone and / or a mineral acid such as hydrochloric acid and nitric acid as necessary, the temperature is preferably 30 ° C. or lower, preferably 30 ° C. or less. While maintaining the temperature at 0 to 20 ° C, an aqueous alkali solution is added. When the temperature exceeds 30 ° C., although depending on other conditions, the particle size generally becomes coarse, and one having a needle-like shape and one having an agglomerated form are formed. Even if the temperature is lower than 0 ° C., the effect is not particularly enhanced, and the cost of the cooling refrigerant or the like increases. In this case, the ratio of tin and indium is Sn
The O ₂ : In ₂ O ₃ weight ratio is from 1:99 to 20:80, preferably from 4:96 to 15:85. If the amount of tin is too large or too small, the desired infrared shielding is obtained. I can not get the nature.

At this time, the concentration at the end of the reaction (SnO ₂
+ In ₂ O ₃ ) concentration is suitably in the range of 2 to 50 g / l, and 2 g
If it is less than 50 g / l, the particle size becomes coarse.

As the alkaline aqueous solution, ammonia water,
Aqueous solutions such as alkali hydroxide, alkali carbonate, and ammonium carbonate can be exemplified, but alkali metal salts containing a component that inhibits conductivity leading to infrared shielding properties are not suitable, and ammonia water and ammonium salts are preferred. Then, the pH of the alkaline aqueous solution is finally adjusted to 5.0 to 9.0.
The hydrate of tin oxide and indium oxide is produced by adding so as to be as follows. If the pH is less than 5.0, the reaction is incomplete, and if the pH exceeds 9.0, some products are deflocculated. Particles are generated.

The addition time of the aqueous alkali solution is not particularly limited, but is preferably about 30 minutes to 12 hours. If the time is less than 30 minutes, the product becomes gel-like, and it becomes difficult to carry out filtration and washing. Causes sintering. If the addition time is longer than 12 hours, the productivity will be reduced and the particle size will be coarse.

[0013] Under the above conditions, the primary particle size is 0.1
A hydrate of tin oxide and indium oxide of about 015 to 0.05 μm is formed. In the present invention, the hydrate may be removed, if necessary, after removing by-produced salts, or after further drying, under an inert gas atmosphere or a reducing gas atmosphere.
The desired tin-containing indium oxide fine powder can be obtained by heat treatment at 200 to 1200 ° C, preferably 300 to 1000 ° C. As an inert gas atmosphere, a nitrogen gas atmosphere, an argon gas atmosphere, or a mixed gas atmosphere thereof is used, and as a reducing gas atmosphere, a hydrogen gas atmosphere, a carbon monoxide gas atmosphere, or a mixture of these and an inert gas is used. Gas atmosphere.

The obtained ITO fine powder has a form as primary particles of about 0.015 to 0.05 μm, whereas the conventional method is a colloidal particle at the stage of forming as a hydrate, Since it is crystallized without inducing sintering in the course of subsequent drying and heat treatment, it is a fine powder having a uniform particle size without coarse particles.

[0015] The paint binder used in the present invention includes:
Any binder can be used as long as it can be used by ordinary coating techniques.Examples include organic binders such as acrylic, vinyl, carbonate, polyester, urethane, epoxy, polypropylene, phenol, polyamide, and polyimide resins. And inorganic binders such as water-soluble silicates and alkyl silicates. In addition, a mixture or a copolymer of these binders may be used, and a heat-resistant resin as a functional resin, an ultraviolet (UV) curable resin, or the like can also be used.

The content of the ITO fine powder is preferably mixed so as to be 40 to 95% by weight in the solid content of the infrared shielding material. If the amount of the ITO fine powder is less than 40% by weight, the infrared ray shielding effect of the obtained coating film is not sufficient. I will be.

The infrared shielding material of the present invention can be obtained by dispersing or dissolving a fine ITO powder and a paint binder in a solvent. Any solvent can be used as long as it can dissolve the paint binder. Methanol, ethanol, n-propanol, i-propanol, n-
Examples include alcohols such as butanol and cyclohexanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, ethers such as methyl cellosolve and ethyl cellosolve, esters such as ethyl acetate and methyl cellosolve acetate, hexane, cyclohexane, toluene and xylene. it can. When a water-soluble resin is used, water can be used as a solvent. The proportion of these solvents used is not particularly limited and may be set according to the purpose of use. However, it is preferable that the solid content in the paint be 10 to 90% by weight in consideration of dispersion, viscosity and the like.

The preparation of the infrared shielding material of the present invention is performed according to the method described in I above.
It is carried out by mixing the TO fine powder, the paint binder and the solvent with a commonly used ball mill, sand mill, paint shaker, three rolls or the like. In this case, a silane-based or titanate-based coupling agent or a surfactant may be added for the purpose of improving dispersibility.

The infrared shielding material of the present invention prepared as described above is applied to a substrate by a coating method such as a spray method, a bar coating method, a dipping method, a doctor blade method, and dried or, if necessary, heat-treated. It is put to practical use.

[0020]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0021] Example 1 stannic chloride _{(SnCl 4 · 5H 2 O)} 5.9g and indium chloride (InCl ₃₎ 75.9 g were dissolved in water 4000 ml, added over 58 minutes a 2% aqueous ammonia thereto Then, the hydrate of tin oxide and indium oxide was co-precipitated by finally adjusting the pH to 7.85. During this time, the liquid temperature was kept at 5 ° C. Next, the coprecipitate was washed, dried, and further mixed gas of nitrogen gas and hydrogen gas (N ₂ : H ₂ = 98.0:
2.0) By baking in an atmosphere at 400 ° C. for 3 hours, a tin-containing indium oxide (IT) having a primary particle size of about 0.02 μm and a uniform particle size that is fine and does not contain coarse particles is used.
O) A fine powder was obtained. 40 g of the ITO fine powder, 8 g of a polyester resin, 50 g of a mixed solvent of (toluene-MEK-ethyl acetate), and 1 g of a nonionic surfactant were mixed for 8 hours by a paint conditioner using zirconia beads as a dispersion medium for 8 hours. Materials were prepared.

Example 2 A coprecipitate of a hydrate of tin oxide and indium oxide obtained in the same manner as in Example 1 was washed and dried, and further a mixed gas of nitrogen gas and hydrogen gas (N ₂ : H ₂ = 99.8: 0.2) By baking in an atmosphere at 400 ° C. for 3 hours, an ITO fine powder having a primary particle diameter of about 0.02 μm and a uniform fine particle size containing no fine particles was obtained. 40 g of the ITO fine powder,
8 g of polyamide resin, (toluene-i-propanol)
50 g of the mixed solvent and 1 g of the nonionic surfactant were mixed for 8 hours by a paint conditioner using zirconia beads as a dispersion medium to prepare an infrared shielding material.

Example 3 A coprecipitate of a hydrate of tin oxide and indium oxide obtained in the same manner as in Example 1 was washed, dried, and further calcined at 400 ° C. for 3 hours in a nitrogen gas atmosphere. Thus, an ITO fine powder having a primary particle diameter of about 0.02 μm and a uniform particle size that is fine and free from coarse particles was obtained. The ITO fine powder 40
g, 8 g of a polyamide resin, 50 g of a mixed solvent of (toluene-i-propanol), and 1 g of a nonionic surfactant were mixed for 8 hours with a paint conditioner using zirconia beads as a dispersion medium to prepare an infrared shielding material.

EXAMPLE 4 3.9 g of stannous chloride (SnCl ₂ .2H ₂ O) and 121.6 g of indium nitrate [In (NO ₃ ) ₃ .3H ₂ O] were added to 400 parts of water.
The solution was dissolved in 0 ml, and 2% aqueous ammonia was added thereto over 73 minutes to adjust the pH to 7.80 to coprecipitate a hydrate of tin oxide and indium oxide. During this time, the liquid temperature was maintained at 20 ° C. Next, the coprecipitate is washed and dried, and further a mixed gas of nitrogen gas and hydrogen gas (N ₂ :
(H ₂ = 98.0: 2.0) By firing at 700 ° C. for 3 hours in an atmosphere, an ITO fine powder having a primary particle diameter of about 0.035 μm and a uniform particle size that is fine and does not contain coarse particles is obtained. Was. 40 g of the ITO fine powder, 8 g of urethane resin,
(Xylene-butyl acetate) 50 g of a mixed solvent and 1 g of a nonionic surfactant were mixed for 8 hours with a paint conditioner using zirconia beads as a dispersion medium to prepare an infrared shielding material.

Example 5 5.9 g of stannic chloride (SnCl ₄ .5H ₂ O) and 75.9 g of indium chloride (InCl ₃ ) were dissolved in 4000 ml of water, and a 4.5% NH ₄ HCO ₃ aqueous solution was added thereto. The hydrate of tin oxide and indium oxide was co-precipitated by adding over 360 minutes to a final pH of 5.8. During this time, the liquid temperature was 2
It was kept at 5 ° C. Next, the coprecipitate was washed, dried, and further mixed with a nitrogen gas and a hydrogen gas (N ₂ : H ₂ = 9).
8.0: 2.0) firing at 900 ° C. for 3 hours in an atmosphere;
An ITO fine powder having a primary particle size of about 0.045 μm and a uniform particle size that is fine and free from coarse particles was obtained. Using the ITO fine powder, an infrared shielding material was prepared in the same manner as in Example 1.

Comparative Example 1 The procedure of Example 1 was repeated except that the solution temperature was maintained at 35 ° C.
TO fine powder was obtained. The fine powder has a minor axis diameter of 0.05 to 0.07.
μm and a needle-like shape having a long axis diameter of 0.30 to 0.35 μm. Using the fine powder, an infrared shielding material was prepared in the same manner as in Example 1.

Comparative Example 2 An ITO fine powder was obtained in the same manner as in Example 1 except that the pH was finally adjusted to 4.5. The fine powder contained a large amount of coarse particles. Using the fine powder, an infrared shielding material was prepared in the same manner as in Example 1.

Comparative Example 3 An ITO fine powder was obtained in the same manner as in Example 1 except that the pH was finally changed to 9.5. The fine powder contained a large amount of coarse particles as in Comparative Example 2. Example 1 using the fine powder
An infrared shielding material was prepared in the same manner as described above.

Comparative Example 4 The procedure of Example 1 was repeated except that the addition time was changed to 20 minutes.
TO fine powder was obtained. The fine powder contained a large amount of coarse particles as in Comparative Example 2. Using the fine powder, an infrared shielding material was prepared in the same manner as in Example 1.

Test Example 1 Each infrared ray shielding material prepared in Examples 1 to 5 and Comparative Examples 1 to 4 was applied on a polyester sheet using a 1 mil doctor blade and dried at room temperature to obtain a coating film. FIG. 1 shows the results of measuring the spectral characteristics of each coating film using a spectrophotometer UV-3100PC (manufactured by Shimadzu Corporation). FIG. 1 shows the results of Examples 1 and 2 and Comparative Examples 1 to 4. FIG. 1 shows that the film formed by the infrared shielding material of the present invention maintains a transmittance of 80% or more in the visible light region while maintaining a transmittance of 120% or more.
It is clear that infrared rays of 0 nm or more are effectively shielded. On the other hand, Comparative Example 1 has excellent infrared shielding properties but low transmittance, Comparative Examples 2 and 3 have the same transmittance but are inferior in infrared shielding properties, and Comparative Example 4 has poor transmittance and infrared shielding properties. It is enough.

[0031]

As described above, since the infrared shielding material of the present invention uses ITO fine powder having a uniform particle size without coarse particles, a coating film formed using this is excellent in transparency and infrared shielding property. If the film is formed on the bulb of an incandescent lamp or halogen lamp, or on the surface of the lamp housing, it will block the strong heat rays from each light source or increase the heat ray radiation. When applied, it prevents radiation loss of indoor warm air in winter, and prevents solar heat rays and discharge of indoor cool air in summer, thus exhibiting energy saving effects.

[Brief description of the drawings]

FIG. 1 is a light transmission spectrum of a film formed from infrared shielding materials obtained in Examples and Comparative Examples.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hitoshi Okada 96-1 Ikuno, Dojo-machi, Kita-ku, Kobe-shi, Hyogo Prefecture Inside the Kobe Research Laboratory, Fuji Titanium Industry Co., Ltd. 96 Ikuno 1 Kobe Research Laboratory, Fuji Titanium Industry Co., Ltd.

Claims (1)

[Claims] 1. The temperature of a solution of a tin salt and an indium salt is set to 3
Tin-containing indium oxide fine powder obtained by heating a hydrate of tin oxide and indium oxide obtained by adding an aqueous alkali solution while maintaining the temperature to 0 ° C. or lower under an inert gas atmosphere or a reducing gas atmosphere. An infrared shielding material comprising: a paint binder and a solvent.