JPH02164744A - Optical body excellent in durability and heat ray reflecting glass - Google Patents

Abstract

PURPOSE:To obtain the optical body excellent in chemical stability and wear resistance by using a tantalum oxide film as the outermost layer on the air side in the optical body obtained by forming >=2 layers of optical thin film on a substrate. CONSTITUTION:The optical body consists of the substrate 1 of transparent or colored glass, plastics, etc., a first layer 2 formed thereon and made of the film of metal, nitride, carbide, oxide, or their composite, and the tantalum oxide layer 3 formed thereon. Alternatively, the optical body is formed with a substrate 10 similar to the substrate 1, a first layer 11 of a transparent dielectric film, a second layer 12 of a nitride film, and a third layer 13 of a tantalum oxide film. Since the optical body has the tantalum oxide film excellent in scratch resistance and having sufficient chemical resistance as the outermost layer on the air side, the wear resistance and chemical stability are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a highly durable optical body having various optical functions.

[Conventional technology] Conventionally, optical functions have been added by forming thin films on transparent substrates such as glass or plastic, such as mirrors, heat-reflecting glasses, low-emission glasses, interference filters, and anti-reflection for camera lenses and eyeglass lenses. There are coats etc.

In a normal mirror, Ag is formed by an electroless plating method, or A1, Cr, etc. are formed by a vacuum evaporation method, a sputtering method, or the like. Among these, the Cr film is relatively strong, so it is partially used as a surface mirror with an exposed coated surface.

Heat-reflective glass has been formed using titanium oxide, tin oxide, or the like by a spray method, a CVD method, or a dipping method. Recently, metal films, nitride films, tin-doped indium oxide (ITO), etc., formed on glass plate surfaces by sputtering have come to be used as heat-reflecting glasses. The sputtering method allows for easy film thickness control and the ability to form multiple films in succession, and in combination with a transparent oxide film, it is possible to design transmittance, reflectance, color tone, etc. For this reason, demand is increasing for architectural applications where design is important.

Low-emissivity glass (low-emissivity glass) that reflects radiant heat from indoor heaters and walls indoors is a three-layer system of ZnO/Ag/ZnO, in which silver is sandwiched between zinc oxides, or ZnO/Ag/Z.
nO/Ag/ZnO 51il system (patent application 1986-280)
644) and is used in the form of double-glazed or laminated glass. In recent years, its popularity in cold regions of Europe has been remarkable.

Antireflection coatings for lenses and the like consist of alternating layers of high refractive index films such as titanium oxide and zirconium oxide and low refractive index films such as silicon oxide and magnesium fluoride. Usually, a vacuum evaporation method is used, and the substrate is heated during film formation to improve scratch resistance.

[Problems to be Solved by the Invention] Antireflection coatings for surface mirrors, single-panel heat-reflecting glasses, lenses, and the like are used with the coated film exposed to the air. Therefore, it must have excellent chemical stability and wear resistance. On the other hand, even low-emissivity glass can be defective due to scratches during transportation or handling before it is made into double-glazed or laminated glass. For this reason, there is a demand for an optical thin film that is stable and has excellent wear resistance and also serves as a protective film.

To improve durability, a chemically stable and transparent oxide film is usually provided on the air side. These oxide films include titanium oxide, tin oxide, zirconium oxide, silicon oxide, etc., and have been selected and used depending on the required performance.

However, although titanium oxide and zirconium oxide have excellent chemical stability, they tend to form crystalline films with large irregularities on the surface, which increases friction when rubbed and has poor wear resistance. .

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

As described above, there is no known thin film that is durable enough to be used as a veneer.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and is directed to an optical body in which an optical thin film consisting of at least two layers is formed on a substrate, in which the outermost layer on the air side is The present invention provides an optical body having excellent durability and characterized by being made of a tantalum oxide film.

FIG. 1 shows a cross-sectional view of an example of an optical body according to the present invention, in which 1 is a substrate made of transparent or colored glass or plastic, and 2 is a substrate made of metal, nitride, carbide, oxide, or any of these materials. The first layer consists of a composite of
3 is a second layer made of tantalum oxide film which is the outermost layer on the air side.
Show layers.

FIG. 2 shows a cross-sectional view of another example of the optical body according to the present invention, in which 10 is various substrates similar to the above substrate 1, 11 is a first layer made of a transparent dielectric film, and 12 is a sectional view of another example of the optical body according to the present invention. The second layer is made of a nitride film, and 13 is the third layer made of a tantalum oxide film, which is the outermost layer on the air side.

As described above, the present invention has at least a two-layer structure, but in some cases, the substrate 1 and the first layer 2 shown in FIG.
and the second layer 3, or the substrate 10 and the first layer 11 in FIG.
, the first layer 11 and the second layer 12, or the second layer 12 and the third layer 1
One layer or a plurality of layers may be formed between the layer and the layer 3 to have the function of improving adhesion, adjusting optical properties, or having various other 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, thereby making possible an optical body with excellent wear resistance and chemical stability. A tantalum oxide film has excellent scratch resistance and sufficient chemical stability, so it is very preferable as the outermost layer of an optical body with excellent durability.

Such tantalum oxide films are not limited to the two components tantalum and oxygen (but may also contain other components to improve durability, adjust optical constants, improve stability during film formation, or improve film formation speed). Further, the tantalum oxide film of the present invention does not necessarily have to be transparent, and it is equally effective even if it is an absorbent film in an oxygen-deficient state or partially contains nitrogen.

The tantalum oxide film that is the outermost layer (second layer 3 or third layer 13)
) is not particularly limited. The color can be determined by considering the transmitted color and reflected color depending on the application, but if it is too thin, sufficient durability cannot be obtained, so depending on the application,
It is desirable that the thickness be 50 Å or more.

On the other hand, since the tantalum oxide film has a relatively high refractive index, if it is too thick, interference effects will occur and the reflected color will be strong. In particular, it is preferably 500 Å or less.

In particular, when applied to automobile glass that requires a natural color, that is, a neutral color, low reflectance, and visible light transmittance of 70% or more, the tantalum oxide film 3 should have a film thickness of 5.
The number of participants is preferably 0 to 200 people.

The method of forming the second layer 3 or the third layer 13 is also not particularly limited. Vacuum deposition method, ion blating method, sputtering method, etc. are all possible, but heat ray reflective glass etc.
When large-area coating is required, such as for automobiles or architecture, reactive sputtering is preferred because of its excellent uniformity.

The film material of the first layer 2 is not particularly limited, and is selected from metals, nitrides, carbides, borides, oxides, silicides, or composites thereof depending on the application or required specifications.

In the case of heat-reflecting glass, the first layer 2 is a heat-absorbing film such as titanium nitride, zirconium nitride, hafnium nitride,
Nitride such as chromium nitride, tanker nitride, or tin-doped indium oxide (ITO), Ag%Au,
Metals such as Pd are mainly selected.

The thickness of the nitride film of the first layer 2 is preferably 1000 Å or less, preferably 500 Å or less, although it depends on the desired transmittance. If the number exceeds 1,000, the absorption of the nitride film becomes too large, and peeling is likely to occur due to internal stress.

When using a nitride film, it is effective to form another layer between the substrate and the nitride film to form a three-layer structure as shown in FIG. 2 in order to increase adhesion to 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, or zinc sulfide.

Considering the adhesion with the nitride film of the second layer 12 and productivity in sputtering, a dielectric film containing the same elements as the nitride film of the second layer is preferable, but it is not limited to this. The combination of the first layer 11/the second layer 2118112 can be various, such as tantalum oxide/titanium nitride, zirconium oxide/titanium nitride, or tin oxide/zirconium nitride.

Although the thickness of the dielectric film 11 is not particularly limited, these dielectrics have a large refractive index, and if an appropriate film thickness is selected, it is possible to adjust the reflectance and color tone using interference effects. In particular, when used in heat-reflecting glass that uses interference effects to achieve high transmission and low reflection in the visible range, the first layer l
The film thickness of l is preferably adjusted in the range of 1,000 to 1,800 in terms of optical film thickness. The refractive index of the first layer 11 is 2.0
It is desirable that the thickness be selected within the range of 2.5 to 2.5, but it may be outside this range as long as the optical film thickness is within an appropriate range. or,
The thickness of the nitride film of the second layer 12 depends on the desired transmittance, but is preferably 1000 Å or less, and optimally ranges from 30 to 500 Å. If the number exceeds 1,000, the absorption of the nitride film becomes too large, the transmittance decreases, and peeling tends to occur due to internal stress.

The first layer 2 is made of tin-doped indium oxide (ITO).
), it is desirable to use ITO with a high carrier concentration and mobility and a film thickness of 4000 Å or more in order to improve the heat ray reflection performance. In order to suppress reflected colors due to interference, it is preferable to form ITO with a thickness of at least 7000 Å or more. On top of that is a tantalum oxide film (second layer 3) as a protective layer.
) to form. Such a low-resistance, high-transmittance, and durable optical thin film can be used not only as heat-reflecting glass, but also as a single-pane window glass for shielding electromagnetic waves, electric windshields for automobile windshields, anti-fog for rear windows, Alternatively, it can be used as a transparent antenna. Furthermore, by taking advantage of its chemical durability, it can also be used as a protective coat for ITO (power supply electrode) of electrochromic display elements.

In the case of low-reflection glass, a film having a higher refractive index than the outermost M3 (tantalum oxide film) on the air side is formed as the first layer 2, or a multilayer structure of three or more layers is used. In the case of a three-layer film, an additional layer is formed between the substrate 1 and the first layer 2, or the first layer 2 and the second layer 3 in Fig. 1, and the refractive index and film thickness are adjusted to improve reflection. reduce the rate.

In the case of low-emission glass, it is effective to use a 3M structure of substrate/oxide film/Ag/tantalum oxide film or a five-layer structure of substrate/oxide film/Ag/oxide film/Ag/tantalum oxide film. Such an oxide film is not particularly limited, but Zn
O is given as an example. Alternatively, a tantalum oxide film may be used.

When applied to a surface mirror, it is sufficient to form a metal such as ROM, which has good adhesion to glass, as the first layer 2 on the substrate, and then form the tantalum oxide film of the present invention as the second layer 3 on top of it. .

The substrate l or 10 is usually made of glass, plastic, or the like. When used as a mirror, the substrate is not limited to this, and an opaque substrate such as metal or ceramic may be used as long as it is smooth.

As another application, although it is not an optical thin film, it can also be used as a protective film for memory disks such as thermal heads and magnetic disks.

Further, in the present invention, the optical thin film may be formed on only one side of the substrate as shown in FIGS. 1 and 2, or may be formed on both sides of the substrate.

[Function] The outermost M on the air side of the optical body in the present invention, that is, the second layer 3 in FIG. 1 or the third layer 13 in FIG. Since it has low resistance and therefore high durability, it plays the role of a protective layer for improving wear resistance and chemical resistance in the optical body of the present invention. Furthermore, by adjusting the refractive index, film thickness, etc.
It has optical functions, that is, functions for adjusting transmittance, reflectance, color tone, etc.

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

In addition, in an optical body having heat ray reflecting performance, the nitride film also has a heat ray reflecting function. In addition, in heat-reflecting glass that aims to achieve high transmission and low reflection in the visible range by utilizing interference effects, the second layer 12 in Fig. 2 has a heat-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.

[Example] (Example 1) A glass substrate was set in a vacuum chamber of a sputtering device.
It was evacuated to X 10-' Torr. After introducing a mixed gas of argon and nitrogen to set the pressure to 2×10°3 Torr, titanium was reactively sputtered to form about 40 titanium nitrides (first layer).

Next, switch to a mixed gas of argon and oxygen and increase the pressure to 2
Approximately 100 tantalum oxides (second layer) were formed by reactive sputtering of tantalum at 10-'' Torr.

Visible light transmittance TV of the heat ray reflective glass obtained in this way,
What are the sunlight transmittance TE, coated surface visible light reflectance F, and glass surface visible light reflectance RVG? 1.1.61
．． It was 6.11.4.9.1 (%). The appearance of the film was neutral in color with no interference color observed. To examine the durability of the membrane, it was immersed in 0.1N sulfuric acid or sodium hydroxide for 120 hours, or in boiling water for 2 hours, but in both cases the change in transmittance and reflectance was within 1%.

Even in a rubbing test with a sand eraser, there were almost no scratches and it showed extremely excellent abrasion resistance.

(Example 2) In the same manner as in Example 1, about 40 people formed a titanium nitride film, and then about 1000 people formed an oxygen tantalum film.

The sample thus obtained had the same chemical resistance as Example 1,
Although it exhibited water resistance and abrasion resistance, strong interference colors were observed in its appearance.

(Comparative Example) In order to see the durability effect of the example, about 40 people formed a titanium nitride film in the same manner as in Example 1, then switched to a mixed gas of argon and oxygen, and the pressure was increased to 2 x 10- “To
rr and reactively sputtering tin to form tin oxide of approx.
00 people formed.

When the sample thus obtained was immersed in sulfuric acid, both the transmittance and reaction rate changed significantly.

[Effects of the Invention] By using a tantalum oxide film as the outermost layer when viewed from the substrate, that is, the outermost layer on the air side, the present invention improves chemical stability and wear resistance as shown in Examples 1 and 2. This makes it possible to obtain an optical body with excellent properties. This allows the optical body of the present invention to be used in severe applications that could not be used conventionally.

In addition, by setting the thickness of the outermost tantalum oxide film to 50 to 200 mm, in addition to the excellent chemical stability and abrasion resistance mentioned above, it has a neutral appearance, high transmittance, and low reflectance. We can provide heat-reflecting glass that is ideal for automobiles.

[Brief explanation of the drawing]

FIG. 1 shows a partial cross-sectional view of an example of an optical body according to the present invention, and FIG. 2 shows a partial cross-sectional view of an example of an optical body having heat ray reflecting performance according to the present invention. 1.10: Substrate 2: Metal, nitride, carbide, boride, oxide film, silicide,
Or a film made of a composite of these (first layer) 3: 11: 12: 13: tantalum oxide film (second layer) transparent dielectric film (first layer) nitride film (second M) tantalum oxide film (third N ) Figure 2

Claims (4)

[Claims] (1) An optical body having excellent durability, in which an optical thin film consisting of at least two layers is formed on a substrate, and the outermost layer on the air side is made of a tantalum oxide film. (2) A highly durable heat-reflecting glass characterized by having a heat-absorbing film and a tantalum oxide film sequentially formed on a substrate. (3) The heat ray reflective glass with excellent durability according to claim 2, wherein a nitride film and a tantalum oxide film are sequentially formed on the substrate. (4) The optical body or heat-reflecting glass with excellent durability according to any one of claims 1 to 3, wherein the tantalum oxide film has a thickness of 50 to 200 Å.