JPH0764599B2 - An optical body with excellent durability and heat ray reflectivity - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical body having various optical functions and excellent in durability.

[Prior Art] Conventionally, a thin film is formed on a transparent substrate such as glass or plastic to add an optical function to prevent reflection of mirrors, heat ray reflection glass, low emission glass, interference filters, camera lenses and spectacle lenses. There is a coat.

In a normal mirror, Ag is formed by an electroless plating method, or Al, Cr, or the like is formed by a vacuum deposition method, a sputtering method, or the like. Among these, the Cr film is relatively strong and is therefore used as a part of the coated surface or exposed surface mirror.

Titanium oxide, tin oxide, and the like have been formed in the heat ray reflective glass by a spray method, a CVD method, an immersion method, or the like. Recently, a metal film, a nitride film, or tin-doped indium oxide (ITO) formed on a glass plate surface by a sputtering method has been used as a heat-reflecting glass. The sputtering method can easily control the film thickness, can form a plurality of films continuously, and can design the transmittance, reflectance, color tone and the like by combining with a transparent oxide film. For this reason, demand is increasing for construction, etc., where design is important.

Low-emissivity glass (low-emissivity glass) that reflects radiant heat from indoor heaters and walls inside the room is made by sandwiching silver with zinc oxide.
It has a three-layer system of ZnO / Ag / AnO or a five-layer system of ZnO / Ag / ZnO / Ag / ZnO (see Japanese Patent Application No. 61-280644), and is used in the form of double-glazing or laminated glass. . In recent years, it has been remarkably popular in cold regions of Europe.

The antireflection coating such as a lens is formed by alternately laminating a high refractive index film such as titanium oxide or zirconium oxide and a low refractive index film such as silicon oxide or magnesium fluoride. Usually, a vacuum vapor deposition method is used, and the substrate is heated during film formation to improve scratch resistance.

[Problems to be Solved by the Invention] A surface mirror, an antireflection coat such as a single-plate heat ray-reflecting glass, and a lens are used in a state where a coated film is exposed to the air. Therefore, it must have excellent chemical stability and wear resistance. On the other hand, even low-emission glass may be defective due to scratches during transportation or handling before it becomes double glazing or laminated glass. Therefore, there is a demand for an optical thin film which is stable and has excellent wear resistance and which also serves as a protective film.

To improve durability, a chemically stable and transparent oxide film is usually provided on the air side. Examples of these oxide films include titanium oxide, tin oxide, zirconium oxide, and silicon oxide, which have been selected and used according to the required performance.

However, although titanium oxide and zirconium oxide have excellent chemical stability, they tend to form a crystalline film and tend to have large irregularities on the surface. Therefore, when they are rubbed, the friction becomes large and the wear resistance is poor. .

On the other hand, tin oxide and silicon oxide are weak against acid and alkali, respectively, and cannot withstand long-term immersion.

As described above, a thin film having high durability that can be used as a single plate is not known.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and in a heat-reflecting optical body in which an optical thin film composed of three layers is formed on a glass substrate, Metal M from the side
The first layer with an optical thickness of 1000-1800Å consisting of the oxide film of
Geometrical film thickness of a nitride film of the same metal M as the first layer 30
~ 500Å second layer, air-side outermost tantalum oxide film with a geometrical film thickness of 50 ~ 200Å third layer is formed in order to provide excellent heat ray reflectivity. An optical body having the same is provided.

FIG. 1 is a sectional view of an example of an optical body according to the present invention, in which 10 is a glass substrate, 11 is a first layer made of a transparent dielectric oxide film, and 12 is a nitride film. The second layer and the third layer 13 are the third layer made of a tantalum oxide film which is the outermost layer on the air side.

Although the present invention has a three-layer structure as described in detail, it includes the substrate 10 and the first layer 11, the first layer 11 and the second layer 12, or the second layer 12 shown in FIG.
One layer or a plurality of layers may be formed between the second layer 13 and the third layer 13 to have a function of improving the adhesive force, adjusting optical characteristics, or other various functions. The most significant feature of the present invention is that a tantalum oxide film is formed on the outermost layer on the air side, which enables an optical body having excellent wear resistance and chemical stability. The tantalum oxide film is very preferable as the outermost layer of the optical body having excellent durability because it has excellent scratch resistance and, at the same time, has sufficient chemical stability.

The tantalum oxide film is not limited to the two components of tantalum and oxygen, and may contain other components for improving durability, adjusting chemical constants, stability during film formation, or improving film formation speed. You can include it. Further, the tantalum oxide film of the present invention does not necessarily have to be transparent, and it is similarly effective even if it is an absorptive film in a state of oxygen deficiency or partially contains nitrogen.

Outermost tantalum oxide film (second layer 3 or third layer 13)
The film thickness of may be determined in consideration of the transmitted color and the reflected color according to the application, but if it is too thin, sufficient durability cannot be obtained, so depending on the application, the geometric film thickness is Used above 50Å.

On the other hand, since the tantalum oxide film has a relatively high refractive index, if it is too thick, an interference effect occurs and the reflected color becomes strong.
In particular, the geometrical thickness of the tantalum oxide film 3 is to be applied to automobile glass that requires a natural color, that is, a neutral color, a low reflectance, and a visible light transmittance of 70% or more.
Used in 50-200Å.

The method for forming the film of the third layer 13 is not particularly limited. Vacuum deposition method,
If any of the ion plating method and the sputtering method is possible, or if a large area coating such as heat ray reflective glass for automobiles or construction is required, the reactive sputtering method having excellent uniformity is preferable.

For the second layer 12, for example, a nitride such as titanium nitride, zirconium nitride, hafnium nitride, chromium nitride, tantalum nitride, or the like is mainly selected.

Since a nitride film is used, it is effective to form another layer between the substrate and the nitride film to form a three-layer structure as shown in FIG. 1 in order to increase the adhesion with the glass interface. The first layer 11 is preferably a transparent dielectric film made of an oxide such as titanium oxide, zirconium oxide, hafnium oxide, tin oxide, tantalum oxide or indium oxide. Considering the adhesion of the second layer 12 to the nitride film and the productivity of sputtering,
A dielectric film containing the same element as the second layer nitride film is used.

Regarding the film thickness of the dielectric film 11, these dielectrics also have a large refractive index, and if an appropriate film thickness is selected, the reflectance and color tone can be adjusted by utilizing the interference effect. In the heat ray reflective glass of the present invention which aims at high transmission and low reflection in the visible region by utilizing the interference effect, the film thickness of the first layer 11 is an optical film thickness of 1000 to 18
It is adjusted in the range of 00Å.

The refractive index of the first layer 11 is preferably selected in the range of 2.0 to 2.5, but even if it is out of this range, the optical film thickness may be in a proper range. The geometric film thickness of the nitride film of the second layer 12 is used in the range of 30 to 500Å. If it exceeds 500Å, the absorption of the nitride film becomes too large, the transmittance decreases, and peeling easily occurs due to internal stress.

In the present invention, the optical thin film may be formed on only one surface of the substrate as shown in FIG. 1, or may be formed on both surfaces of the substrate.

[Function] The outermost layer on the air side of the optical body in the present invention, that is, the third layer 13 in FIG. 1 is made of a tantalum oxide film, and has a smooth surface and low frictional resistance, which results in high durability. Therefore, it has a role of a protective layer for improving abrasion resistance and chemical resistance in the optical body of the present invention. Furthermore, by adjusting the refractive index and film thickness, the optical function, that is,
It has a function of adjusting transmittance, reflectance, color tone, and so on.

In the present invention, the layers other than the outermost layer mainly have an optical function and are responsible for transmission and reflection performance.

Further, in the optical body having a heat ray reflecting performance, the nitride film has a heat ray reflecting function. Further, in the heat ray reflective glass aiming at high transmission and low reflection in the visible region by utilizing the interference effect, the second layer 12 in FIG. 1 has a heat ray reflecting function, and the first layer 11 and the third layer 13 has a function of preventing reflection of the nitride film in the visible range.

EFFECTS OF THE INVENTION The present invention provides an optical body having excellent chemical stability and wear resistance by using a tantalum oxide film as the outermost layer viewed from the substrate, that is, the outermost layer on the air side. It makes it possible. As a result, the optical body of the present invention can be used for severe applications that could not be used conventionally.

Also, the geometrical thickness of the outermost tantalum oxide film should be 50-200.
By setting it as Å, it is possible to provide the optimum heat ray-reflecting glass for automobiles, which has neutral appearance, high transmittance and low reflectance in addition to the above-mentioned excellent chemical stability and abrasion resistance.

[Brief description of drawings]

FIG. 1 shows a partial cross-sectional view of an example of an optical body having heat ray reflection performance according to the present invention. 11: Transparent dielectric film (first layer) 12: Nitride film (second layer) 13: Tantalum oxide film (third layer)

Claims (1)

[Claims] 1. A heat-reflecting optical body comprising an optical thin film comprising three layers formed on a glass substrate, and a first layer having an optical film thickness of 1000 to 1800Å consisting of an oxide film of metal M from the substrate side. , A second layer having a geometrical film thickness of 30 to 500Å made of the same metal M nitride film as the first layer, and a third layer having a geometrical film thickness of 50 to 200Å made of an outermost tantalum oxide film on the air side. A heat-reflecting optical body having excellent durability, characterized in that