JPS61132902A - Transparent film for blocking ultraviolet ray and infrared ray - Google Patents

Abstract

PURPOSE:To obtain a visible ray transmittable film which absorbs UV rays when combined with a transparent body such as glass, reflects IR rays, has high adhesive strength and is chemically and thermally stable by forming said film of the thin laminated films consisting of a thin zinc oxide film and a thin zinc oxide film contg. Al at a specified ratio. CONSTITUTION:The thin transparent ZoO film is formed by sputtering, etc. of zinc oxide on a transparent base body consisting of glass or plastic and a thin transparent ZnO film contg. 0.4-10atomic% Al is formed on said film. An Al metal, oxide, org. Al compd., Al halide, etc. are used together with ZnO for an Al-contg. ZnO target. Al may be subjected to thermal diffusion, etc. after the formation of the ZnO film. The ZnO film and the Al-contg. ZnO film may be formed in reverse order. The laminated films which absorb UV rays and reflect IR rays are thus obtd. The laminated films are suitable for preventing the temp. rise in a room, color fading of articles, etc. in a show window, automobile, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a transparent film that blocks the transmission of ultraviolet and infrared rays.

(Prior art) Generally, glass and other transparent materials are used for windows of buildings such as houses and buildings, and automobiles. It has the property of transmitting electromagnetic waves to the outside world and absorbing most infrared rays.

(Problem to be solved by the invention) However, since this type of transparent material transmits ultraviolet rays, it causes fading of the object, rapidly reducing the value of products inside the seat window and seat covers inside the car. , the transmission and absorption of infrared rays causes heat generation and temperature rise, which has become a serious problem in building design, such as the rise in temperature inside cars under the scorching sun and the decline in the cooling effect of tablets and other devices in the summer. Therefore, in order to solve these problems, it would be ideal to have a product that blocks sunlight's ultraviolet and infrared rays and transmits only visible light, but this is currently not widely used. This is impossible to achieve with transparent materials such as window glass and plastic.

On the other hand, as a transparent material that satisfies the above requirements to some extent, an indium oxide-tin oxide based transparent conductive film (ITo film) is used.
However, the inherent flaw in this ITO film is that it transmits wavelengths of approximately 300 nm or more, making it difficult to obtain sufficient ultraviolet blocking properties.Furthermore, due to the following drawbacks, it is not suitable for aircraft windows. There is a problem in that it is difficult to put it into practical use in a wide range of applications, except for special uses such as commercial use. That is, (1) Raw materials are expensive. In particular, since the rare metal indium makes up most of the composition, the raw materials are expensive and there are resource issues.

(2) In order to obtain good reflection characteristics for infrared rays,
For manufacturing purposes, high temperature treatment of about 300 to 600°C is required.

(3) Since it is difficult to obtain a film with a smooth surface and the film surface is also chemically unstable, optical properties may be adversely affected when other films are formed on the ITO film.

Accordingly, an object of the present invention is to obtain a transparent film that can be manufactured inexpensively and easily and that sufficiently blocks the transmission of ultraviolet and infrared rays.

C. Means for Solving Problems) The present invention solves the above problems by combining a crystalline thin film made of zinc oxide and a crystalline thin film made of zinc oxide containing aluminum.

The ultraviolet and infrared blocking transparent film according to the present invention is produced by forming a zinc oxide thin film and an aluminum-containing oxide film on a transparent substrate by any known thin film forming method such as sputtering, vacuum evaporation, chemical vapor deposition, or anodic oxidation. It can be formed by laminating zinc thin films.

As the transparent substrate, commercially available glass or plastic transparent materials may be used. Alternatively, a zinc oxide thin film containing aluminum may be laminated after directly forming a zinc oxide thin film on a relatively thick transparent substrate, or vice versa, a zinc oxide thin film may be formed after forming an aluminum-containing zinc oxide thin film. Furthermore, the two layers may be formed on a thin plastic transparent film, and this may be attached to the surface of another transparent material.

The content of aluminum contained in the zinc oxide thin film is
The amount is preferably 1 to 20 atom %, preferably 2 to 4 atom %, based on zinc atoms. This is because if the aluminum content is less than 1 atomic %, the effect of its addition cannot be obtained, and if it exceeds 20 atomic %, the crystallinity deteriorates. Note that the content of aluminum is 0.4 to 10 atomic % based on all the constituent elements of the aluminum-containing film.

In addition, as a method for incorporating aluminum into the zinc oxide thin film, it is preferable to introduce aluminum in the form of aluminum metal, oxide, organometallic, helodenide, etc. into the raw material during the thin film forming process. It is also possible to thermally diffuse the aluminum after formation.

(Function) Zinc oxide (ZnO) is a direct transition type semiconductor with an energy gap of approximately 3.3 eV at room temperature, and a degenerate n-type semiconductor is obtained by donor levels due to intrinsic lattice defects, and it is relatively easy to crystallize. A thin film is formed and exhibits extremely steep ultraviolet absorption characteristics. On the other hand, zinc oxide does not exhibit sufficient infrared absorption properties because its electron density is difficult to exceed the order of 1020 cm-2. However, when aluminum is introduced into it, aluminum acts as a donor and
It is possible to achieve an electron density on the order of 0"c-13, and it shows good infrared reflection characteristics. Even if the raw material is a direct transition type, if the crystallinity is highly disordered or it is amorphous, there will be a steep It is not possible to obtain the absorption edge.

Next, examples of the present invention will be described.

Example 1 A window glass with a thickness of 2 mm was used as a transparent substrate, and zinc oxide was used as tarded on the transparent substrate kept at room temperature.
After forming a zinc oxide thin film with a thickness of 00 nm using a high-frequency magnetron sputtering device, sputtering is performed using a tarded material containing about 3 at% of aluminum to Zn atoms to form an aluminum-containing zinc oxide thin film with a thickness of about 50 Or + L11. A transparent film was obtained by laminating the layers. The optical properties of the obtained transparent film are shown in FIGS. 1 and 2.

In FIG. 2, the solid line shows the transmission spectrum, and the broken line shows the reflection spectrum in the infrared region.

As is clear from the results shown in FIGS. 1 and 2, the transparent film according to the present invention completely absorbs or reflects ultraviolet rays with a wavelength of about 39 Or+m or less, and almost reflects infrared rays with a wavelength of about 900 nm or more. Shows sharp ultraviolet and infrared blocking properties.

When we fitted window glass with this transparent film into a window and measured the temperature rise due to irradiation with sunlight on a clear day, we found that the temperature rise was significantly lower than that of conventional window glass alone, and it was found to have a remarkable effect of preventing infrared transmission. Ta. In addition, when colored printed matter and colored clothing were irradiated with sunlight that had passed through a window glass on which the transparent film of the present invention was formed over a period of one month, it was found that the color fading of pigments was significantly greater than when sunlight that had passed through a single window glass was irradiated. The amount of UV rays was significantly reduced, and a remarkable effect of preventing ultraviolet transmission was observed.

Example 2 As a transparent substrate material, a commercially available transparent film (Saran Wrap, trade name of Asahi Ka I & Co., Ltd. Plastic R & Resin Sheet, thickness approximately 20 mm) was used.
μ■) to a thickness of 100n+1 in the same manner as in Example 1.
An aluminum-containing zinc oxide thin film having a thickness of about 600 nm and containing about 1.5 atomic % of aluminum was stacked on a substrate. The transmission spectrum and absorption spectrum of the obtained ultraviolet and infrared blocking transparent film are as follows:
It was almost the same as that of Example 1.

Example 3 A commercially available plastic sheet (manufactured by Master Co., Ltd., approximately 125 μm in thickness) was used as the transparent substrate material, and the same procedure as in Example 1 was used to coat the substrate with a thickness of about 100 μm. After forming a 100 tv+ zinc oxide thin film, an aluminum-containing zinc oxide thin film having a thickness of about 600 nm and containing about 1.5 atomic % of aluminum was laminated thereon to obtain a transparent film for blocking ultraviolet rays and infrared rays.

The obtained ultraviolet and infrared blocking transparent film exhibited transmission spectra and absorption spectrum characteristics similar to those of Example 1. (Effects of the Invention) As is clear from the above description, the ultraviolet and infrared blocking thin film according to the present invention employs a zinc oxide thin film as the main raw material, and therefore can achieve extremely sharp ultraviolet blocking properties. In addition, the raw materials zinc and aluminum are extremely cheap and abundant resources compared to indium, and cause very little pollution, and the zinc oxide thin film and aluminum-containing zinc oxide thin film that make up the transparent film are Since they are basically made of the same crystalline zinc oxide, a high-quality crystalline thin film is formed with less stress in the film, and it is also extremely stable mechanically, resulting in low manufacturing costs. Furthermore, even when both the zinc oxide thin film and the aluminum-containing zinc oxide thin film are formed at a low temperature of about 150° C. from room temperature, good ultraviolet absorption and infrared reflection characteristics can be obtained, so that production is easy. In addition, the surfaces of zinc oxide thin films and aluminum-containing zinc oxide thin films are extremely smooth, and the thin films have strong adhesion to substrates such as glass.
It is also thermally and mechanically stable, making it ideal for applications requiring multilayer coatings such as protective films.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the transmission blocking rate and wavelength of the transparent film for blocking ultraviolet rays and infrared rays according to the present invention, and FIG. 2 is a graph showing the optical characteristics of the transparent film for blocking ultraviolet rays and infrared rays according to the present invention. be. Patent applicant Osaka Tokushu Alloy Co., Ltd. Agent Patent attorney Aoyama Aoyama and 2 others Figure 1 400 5m 12001φ0 200024002
800 tables (nm) 1112 m (pml)

Claims (3)

[Claims] (1) A transparent film for blocking ultraviolet and infrared rays consisting of a zinc oxide thin film and an aluminum-containing zinc oxide thin film. (2) Claim 1, wherein the aluminum-containing zinc oxide film contains 0.4 to 10 atomic percent of aluminum.
Transparent membrane described in section. (3) Claim 1, wherein the zinc oxide thin film and the aluminum-containing zinc oxide thin film are formed on a transparent substrate.
Transparent membrane described in section.