JPH10265718A - Coating material for formation of glare-proof infrared ray blocking film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a glare-proof infrared ray blocking film being transparent to visible light, capable of effectively blocking infrared rays containing near- infrared rays and excellent in glare-proof property, e.g. on the surface of window glass for houses and automobiles, further, various display units (e.g. CRT or PDP). SOLUTION: This coating material is obtained by forming a coating film containing tin doped indium oxide (ITO) powder having <=0.5 μm average primary particle diameter (preferably having infrared rays-blocking ability capable of thoroughly blocking >=90% of infrared rays on wavelength side longer than at least 1,000 nm wavelength) in an amount of 25-95 wt.% based on total amount of binder solid content and further containing powder having 1-10 μm average primary particle diameter and comprising one or two or more kinds of magnesium oxide and magnesium fluoride in an amount of 0.1-5 wt.% based on total amount of binder solid content and ITO powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
(I.e., transparent), and can selectively block infrared light including near infrared without losing its transparency, and a coating for forming an antiglare infrared shielding film excellent in antiglare effect, The present invention relates to a substrate on which an anti-glare infrared shielding film formed from the coating material is formed, particularly to a transparent substrate. The paint for forming an antiglare infrared shielding film of the present invention can be applied to window glasses of automobiles and houses, and various display devices such as CRTs, LDCs, and PDPs.

[0002]

2. Description of the Related Art It is described in, for example, JP-A-7-70306 that tin-doped indium oxide (ITO) powder is transparent to visible light and can block infrared rays, and contains ITO powder. A paint for forming a transparent infrared shielding film has already been proposed, for example, in Japanese Patent Application Laid-Open No. 7-70482.

On the other hand, as a method for imparting antiglare properties to a substrate surface, a method of forming fine irregularities on a glass surface by, for example, treating the glass surface with hydrofluoric acid to which ammonium acid fluoride is added and etching the glass surface, It has been generally adopted as a non-glare treatment for a cathode ray tube or the like.

In order to enhance the anti-glare effect of this method, JP-A-3-255402 discloses hydrofluoric acid, ammonium acid fluoride, oxide powder (eg, powder of silica, sodium silicate, glass, etc.), and An anti-glare treatment method for treating a substrate surface with a treatment solution containing an organic acid is described.

[0005] These methods using hydrofluoric acid treatment can be applied only when the substrate is glass, and the treatment liquid is very corrosive, so expensive equipment is required, and the drainage treatment is troublesome. There is. Therefore, it has been attempted to impart antiglare properties by forming a resin film.

For example, Japanese Patent Application Laid-Open No. 1-2232301 discloses that an ultraviolet curable acrylic primer layer having a thickness of 0.1 μm or less is coated on a calcium carbonate powder or a conductive metal oxide powder having an average particle size of 0.1 μm or less (eg, A method for forming a UV-curable hard coating containing (i.e., ITO powder) and adjusting the surface roughness is described.

[0007]

In recent years, with respect to the window glass of automobiles and houses, the effect of blocking infrared rays has been improved in order to improve the energy efficiency of cooling and heating, and at the same time it has been troublesome for other cars and houses. It has been required to reduce the reflectance of visible light so as not to cause the problem.

However, when the coating material for forming an infrared shielding film containing the above-mentioned ITO powder is used, although the infrared shielding effect of the coating film is sufficient, the visible light reflectance of the coating film is almost equal to that of the substrate. However, the anti-glare property cannot be imparted because the anti-glare property is not low. On the other hand, a coating film formed by the above-described conventional method for imparting antiglare properties has no infrared blocking effect.

For example, in order to impart an antiglare property to a coating for forming an infrared shielding film containing ITO powder, Japanese Patent Application Laid-Open No.
It is conceivable to add fine calcium carbonate powder described in JP-A-232301. However, when a sufficient amount of fine calcium carbonate powder is added to impart antiglare properties, the transparency of the coating film is significantly impaired.

An object of the present invention is to provide a coating for forming an anti-glare infrared shielding film which is transparent to visible light, can effectively block infrared rays including near infrared rays, and has an excellent anti-glare effect. It is to provide.

[0011]

Means for Solving the Problems As a result of repeated studies to solve the above-mentioned problems, the present inventors have found that silica having a specific average primary particle diameter is contained in a coating material for forming an infrared shielding film containing ITO powder. It has been found that the addition of a powder of magnesium oxide and / or magnesium fluoride makes it possible to obtain a coating film exhibiting excellent antiglare properties while maintaining transparency and an infrared shielding effect.

Here, the present invention provides a method for preparing a binder
Including tin-doped indium oxide (ITO) powder having an average primary particle diameter of 0.5 μm or less and powder having an average primary particle diameter of 1 to 10 μm comprising one or more of silica, magnesium oxide and magnesium fluoride. A paint for forming an antiglare infrared shielding film, which is a feature.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The paint for forming an antiglare infrared shielding film according to the present invention contains a binder solution (ie,
Binder and its solvent), an ITO powder dispersed in the binder solution, and an antiglare-imparting powder comprising one or more of silica, magnesium oxide and magnesium fluoride.

The kind of the binder is not particularly limited, and any of an organic binder and an inorganic binder can be used as long as a transparent film can be formed, and a film having characteristics suitable for the use of the paint of the present invention can be obtained. What is necessary is just to select from what can be formed.

The organic binder may be either a thermoplastic organic resin or an organic resin capable of forming a crosslinked film such as a thermosetting type, an ultraviolet setting type, and an electron beam setting type. For example, when a coating film is required to have high hardness or high scratch resistance, it is preferable to use an organic resin capable of forming a crosslinked film. Conversely, for applications requiring flexibility of the coating film, a thermoplastic resin is preferred. Examples of suitable organic binders include acrylic resins, urethane resins, polycarbonate resins, polyester resins, epoxy resins, silicone resins, polyimide resins, polyvinyl chloride resins, melamine resins, alkyd resins, and the like. Preferred organic binders are acrylic resins, urethane resins, polyester resins, and silicone resins.

As the inorganic binder, an organic compound capable of forming a metal oxide film by hydrolysis or thermal decomposition can be used. Examples of such compounds include metal alkoxides and carboxylate salts. Specific examples include tetraalkoxysilanes such as tetraethoxysilane (ethyl silicate), metal alkoxides such as titanium tetraalkoxide, zirconium tetraalkoxide and aluminum trialkoxide, and lower carboxylate salts of transition metals such as titanium and zirconium (eg, , Butyrate, isopropionate, etc.).
Preferred inorganic binders are tetraalkoxysilanes, especially ethyl silicate. Metal alkoxides such as tetraalkoxysilane can be used in a partially hydrolyzed state in order to promote film formation.

As a solvent for dissolving the binder, an appropriate solvent may be used depending on the kind of the binder. This solvent may be either an organic solvent or water. Further, the binder solution may be an emulsion (emulsion liquid) or a sol (particularly when the solvent is water). The concentration of the binder in the binder solution is not particularly limited. The concentration of the binder may be adjusted so that the paint finally obtained by adding the ITO powder and the antiglare property imparting powder has a viscosity suitable for application.

The ITO powder is added to the paint in order to give the coating film the ability to block infrared rays including near infrared rays while maintaining transparency. An ITO powder having an average primary particle diameter of more than 0.5 μm has an infrared blocking effect, but significantly impairs the transparency of the coating film. Therefore, an ITO powder having an average primary particle diameter of 0.5 μm or less is used. The average primary particle diameter of the ITO powder is preferably 0.2 μm or less, more preferably 0.1 μm or less.

It is preferable that the ITO powder has an infrared shielding ability to block at least 90% or more of infrared rays having a wavelength longer than 1000 nm. Such ITO powder is
As described in JP-A-7-70482, for example, a coprecipitate of indium hydroxide and tin hydroxide is mixed with a pressurized inert gas atmosphere (eg, 2 kgf / cm ² or more, particularly 5 to 60 kgf). / c
It can be manufactured by calcining in an atmosphere of argon, neon, nitrogen or a mixture of these gases pressurized to m ² ) or by heat-treating the ITO powder in a pressurized inert gas atmosphere. The firing or heat treatment temperature is 350 ~ 1000 ℃, especially 40
It is preferably in the range of 0 to 800 ° C. Sn / (In +) of ITO powder
The atomic ratio of Sn) is preferably in the range from 0.01 to 0.15.

The amount of the ITO powder to be added is 25 to 95 wt.% Based on the total amount of the ITO powder and the solid content of the binder in the paint (when the binder is an inorganic type, the amount in terms of metal oxide). %, More preferably 40%.
It is in the range of 9090 wt%. If the content of the ITO powder is too large, the transparency is impaired, and if it is too small, the effect of blocking infrared rays tends to be insufficient.

By simply adding the ITO powder to the binder solution, the visible light reflectance of the formed coating film is almost the same as the reflectance of the substrate, and low reflectivity (therefore, antiglare property) is not provided. Therefore, in the present invention, in order to impart low reflectivity (antiglare property) to the coating film without impairing the transparency and the infrared shielding effect, one or two or more selected from silica, magnesium oxide and magnesium fluoride are provided. One or more anti-glare imparting powders are added together with the ITO powder. As the silica powder, either amorphous or crystalline silica can be used, but amorphous is preferable in order to obtain excellent antiglare properties. The shape is preferably spherical.

The powder having antiglare properties has an average primary particle diameter of 1 to 1.
Use one within the range of 10 μm. If the average primary particle size of the powder is less than 1 μm, the desired excellent anti-glare property cannot be secured, and if the average primary particle size exceeds 10 μm, transparency is impaired. The average primary particle size of the antiglare powder is preferably selected according to the thickness (film thickness) of a coating film formed from the coating material according to the present invention. Specifically, it is preferable to use an antiglare imparting powder having an average primary particle diameter larger than the thickness of the coating film.

The amount of the antiglare powder is preferably 0.1 to 5 wt.% Based on the total amount of the solid content of the binder (in the case of an inorganic binder, in terms of metal oxide) and the ITO powder. %, More preferably 0.5 to 2% by weight. If the amount of the powder is too small, the antiglare property of the coating film becomes insufficient, and if it is too large, the transparency of the coating film tends to be impaired.

The coating for forming an antiglare infrared shielding film of the present invention may contain one or more suitable additives which can be added to the transparent coating, in addition to the above essential components. Examples of such additives include crosslinking agents, polymerization catalysts, surfactants (including dispersants and wetting agents), coupling agents such as silane coupling agents, defoamers, and hydrolyzable inorganic binders. In such a case, a hydrolysis catalyst (eg, acid), an ultraviolet absorber, a dye, and the like can be used.

When the coating for forming an anti-glare infrared shielding film of the present invention is applied to an appropriate substrate, and the coating is dried or cured (heat-cured, ultraviolet-cured, etc.) as necessary, a transparent anti-glare infrared-ray A barrier film is formed on the surface of the substrate. The thickness of the coating film (the thickness after drying) is not particularly limited, but is usually 0.5 to 8 μm.
Is more preferable, and it is more preferably 1 to 5 μm.

Since this coating film is transparent, the substrate is preferably a transparent substrate, but need not necessarily be a transparent substrate. For example, a coating film of the present invention may be formed on the surface of an opaque substrate having a beautiful surface, color, pattern or display. Examples of transparent substrates include glass, PET films and other transparent resin films.

Specific examples of glass products to which the paint of the present invention can be applied include window glass for houses, buildings, etc., windows, partition glass, glass for greenhouses, window glass for automobiles, and cathode ray tubes (CRTs). Tube), liquid crystal display (L
Various display devices, such as a CD) panel and a plasma display panel (PDP).

A PET film having a PET film as a substrate and an anti-glare infrared shielding film formed on one surface thereof using the coating material of the present invention.
The T film can be used, for example, as a transparent film to be applied to window glass of an existing house, glass for a greenhouse, etc. in order to impart antiglare properties and infrared shielding properties. As the PET film, for example, a film having a thickness of about 25 to 250 μm is preferable. In this case, since the PET film is flexible, the binder is preferably an acrylic resin, a polyester resin, a urethane resin, or the like.

PE having an antiglare infrared blocking film on one side
The T film is preferably applied with an adhesive in advance on the back side of the PET film, and a release film is laminated on the adhesive layer in order to easily attach the film to a window glass or the like. . As a result, the PET film can be immediately used for attaching to a window glass or the like simply by peeling off the release film. When affixing to a house window glass,
UV absorbers (eg, benzophenone-based, benzotriazole-based, triazine-based, etc.) are added to the adhesive layer to prevent the recent adverse effects of ultraviolet rays due to the ozone hole on the human body (such as the occurrence of melanoma). Is preferably contained. As the adhesive, for example, an acrylic adhesive is preferable. The release film may be a conventional one, for example, a silicone-treated polyester film.

[0030]

EXAMPLE An ITO powder, a binder, a solvent, and an antiglare-imparting powder were mixed at the particle size and content shown in Table 1,
The coating was prepared by uniformly dispersing the powder with a conventional paint shaker. In addition, among the binders shown in Table 1, as the silica, a partial hydrolyzate of tetraethoxysilane (ethyl silicate) was actually used. This forms a silica coating after drying.

Each of the ITO powders used was obtained by calcining a coprecipitate of indium hydroxide and tin hydroxide at a temperature of 400 to 800 ° C. in a pressurized nitrogen atmosphere at a pressure of 10 to 40 kgf / cm ^2. It was manufactured and had an infrared blocking ability of blocking 90% or more of infrared rays at least on the longer wavelength side than 1000 nm. Table 1 also shows the minimum wavelength (minimum cutoff wavelength) showing a blocking ability of 90% or more in the infrared region.

Each of the obtained paints was applied to a substrate shown in Table 2 using a bar coater so that the dry film thickness was 2 μm (1 μm only when the binder was silica), and 100 ° C.
To form a coating film on the surface of the substrate.

With respect to the substrate on which the coating film was formed, JI
According to SR 3106, measurement of visible light reflectance to evaluate anti-glare property, measurement of visible light transmittance and haze to evaluate transparency, and measurement of solar transmittance to evaluate infrared blocking effect Was done. All of the measured values are actual measured values from which the value of the substrate has not been subtracted. If the visible light reflectance is 6% or less, the antiglare property is good, and the visible light transmittance is
If the haze is 2 or less at 80% or more, the transparency is good, and if the solar transmittance is 65% or less, it can be determined that the infrared shielding ability is good. These measurement results are also shown in Table 2.

[0034]

[Table 1]

[0035]

[Table 2]

As can be seen from the results shown in Table 2, when only the ITO powder was added to the binder solution as in Comparative Example 1, the coating film had a visible light reflectance of about 80% and a haze of 1.
Although the transparency is good at 2% and the solar transmittance is good at 60% or less, the visible light reflectance is as high as 9.7%.
It is almost the same as the visible light reflectivity of the ET substrate, and does not have the low reflectivity required for antiglare properties.

On the other hand, in Example 1 in which the antiglare property-imparting powder was added to the paint of Comparative Example 1 according to the present invention, the high visible light transmittance, low haze, and solar transmittance of the coating film of Comparative Example 1 were reduced. 5.4% visible light reflectance while maintaining approximately the same value
Has dropped. That is, it can be seen that the addition of the antiglare powder imparts good antiglare properties while maintaining transparency and infrared blocking ability.

Similarly, as shown in Example 2 and below, even if the binder is another organic resin or silica, the required antiglare property is imparted while maintaining good transparency and infrared shielding ability. did it.

However, as shown in Comparative Example 2 and below, if the average primary particle size of the antiglare powder is too small, the effect of imparting antiglare properties cannot be obtained. Conversely, if it is too large, the transparency of the coating film will be poor. Significantly inhibited. On the other hand, if the amount of the antiglare powder was too small, the effect of imparting antiglare properties could not be obtained, while if it was too large, the transparency of the coating film, particularly haze, was significantly inhibited. further,
In the calcium carbonate anti-glare imparting powder, even if the average primary particle diameter and the amount of addition is appropriate, the effect of imparting anti-glare is small,
If a large amount is added, some anti-glare properties can be obtained, but the transparency of the coating film is impaired. The results were similar for other powders.

[0040]

As described above, the coating film obtained by the coating material for forming an antiglare infrared shielding film according to the present invention has the following properties:
While exhibiting excellent anti-glare properties, it also has excellent transparency and infrared blocking effect. Therefore, for example, when this coating is applied to a window glass of an automobile or a house, etc., it is possible to obtain an improvement in energy efficiency of cooling and heating by an infrared ray blocking effect and to achieve an anti-glare effect while sufficiently ensuring indoor brightness. It is possible to prevent inconvenience to other vehicles and houses caused by reflected light due to the nature.

Also, when applied to various display devices such as CRT tubes, LCD panels, PDPs, etc., it is possible to prevent the malfunction of the infrared sensor due to the leakage of the infrared ray due to the infrared ray blocking effect, and to achieve good transparency and prevention. The effect that the display becomes easy to see due to the glare is exhibited. Furthermore, PET
The film formed with this coating film is useful for imparting antiglare properties and infrared shielding properties to window glass and the like of existing houses.

Claims (7)

[Claims] 1. The method according to claim 1, wherein the binder solution has an average primary particle size of 0.
5 μm or less of tin-doped indium oxide (ITO) powder and one or more of silica, magnesium oxide and magnesium fluoride having an average primary particle size of 1 to 2
A coating material for forming an antiglare infrared shielding film, comprising a 10 μm antiglare powder. 2. The coating material for forming an antiglare infrared ray shielding film according to claim 1, wherein the ITO powder has an infrared ray shielding ability of totally blocking 90% or more of infrared rays having a wavelength longer than 1000 nm. 3. The content of the ITO powder is 25 to 95 wt% based on the total amount of the binder solids, and the content of the antiglare powder is based on the total amount of the binder solids and the ITO powder. 3. The coating composition according to claim 1, wherein the content is 0.1 to 5% by weight. 4. A substrate having an anti-glare infrared shielding ability, wherein an anti-glare infrared shielding film formed from the paint according to claim 1 is formed on the surface of the substrate. 5. The substrate according to claim 4, wherein said substrate is a transparent substrate. 6. The substrate according to claim 4, wherein said substrate is glass. 7. The transparent substrate is a PET film,
The substrate according to claim 4, wherein an adhesive and a release film are laminated on the back side of the PET film.