JPS634507B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a selectively transparent laminate. More specifically, the present invention relates to a selective light transmitting laminate obtained by laminating a metal layer and a high refractive index antireflection layer on a transparent substrate. The selective light transmitting laminate is transparent to light in the visible light range, for example, but has the ability to reflect infrared light, so it is useful as a transparent heat insulating film.
Therefore, it can be used in solar energy collectors (water heaters), solar thermal power generation, greenhouses, building windows, refrigerated and frozen cases, etc. Particularly in modern buildings, the function of transparent insulating windows that can prevent solar energy utilization and energy radiation from windows that occupy a large proportion of the wall surface is expected to become increasingly important in the future. Furthermore, it is of great importance as a film for greenhouses, which is necessary for the cultivation of wild vegetables, citrus fruits, etc., and the cultivation of fruits, etc. As described above, selective light transmitting laminates are important from the viewpoint of solar energy utilization, and the industry has desired that homogeneous, high-performance films can be supplied industrially at low cost and in large quantities. Conventionally known selective light transmitting films in such selective light transmitting laminates include metal thin films such as gold, copper, silver, and palladium, and compound semiconductor films such as indium oxide, tin oxide, and copper iodide. It is known that conductive metal films such as gold, silver, copper, and palladium are selectively transparent over a certain wavelength range. As a selective light transmitting film with high infrared light reflecting ability, an indium oxide film or a tin oxide film with a thickness of several thousand angstroms, and a laminated film of a metal film and a transparent conductor film are known. However, at present, selective light transmitting films with excellent performance have not yet been produced industrially and at low cost. That is, it is difficult to obtain the above-mentioned metal thin film with high visible light transmittance because metal has high reflective ability or absorbing ability over a wide wavelength range. When visible light transmittance is increased, infrared light reflection ability is significantly reduced. If the thickness of the metal thin film is increased in order to improve the infrared reflective ability, the visible light transmittance will be significantly lowered, making it impossible to obtain a selective light transmitting film that is excellent in both properties. The above compound semiconductor thin film is formed by a thin film forming method in vacuum such as vacuum evaporation method or sputtering method. The film formation rate is actually slow due to the control, and the size of the evaporation source is limited, which limits its application to large-area substrates.It lacks industrial productivity and cannot be a cheap product. . In order to obtain films with excellent selective light transmission using semiconductors such as indium oxide, a film of semiconductors such as indium oxide with a film thickness of several thousand angstroms has been proposed, but the production speed of the film is significantly slowed down. Therefore, a large amount of valuable resources such as indium are consumed, and as a result, the manufacturing cost of the membrane increases significantly. Furthermore, this film does not have sufficiently high infrared light reflectivity. The selective light transmitting film described above is a laminate composed of a metal thin film and a transparent high refractive index thin film. For example, a selective light transmitting film composed of one metal thin film layer and two transparent high refractive index thin film layers. Examples include vacuum evaporation,
formed by reactive vapor deposition or sputtering
Bi ₂ O ₃ /Au/Bi ₂ O ₃ , ZnS/Ag/ZnS or TiO ₂ /
Laminated films with a sandwich structure such as Ag/TiO ₂ have been proposed. Incidentally, a laminated film composed of one layer of metal thin film and one layer of transparent high refractive index thin film can also serve as a selective light transmitting film, although it is insufficient. As mentioned above, when silver is used as the metal layer, due to the optical properties of silver itself, it has particularly excellent transparency in the visible light region and reflection properties for infrared light, and also has favorable properties in terms of conductivity. It is particularly excellent as a laminated film because of the fact that it is However, the laminated film consisting of a silver thin film layer covered with a transparent high refractive index thin film layer has a problem in environmental stability because its performance deteriorates due to heat, light, gas, etc. Since most of the causes of this deterioration are surface diffusion of silver due to environmental factors, improvement has become a very important issue. The present inventors have conducted intensive research to improve the environmental stability of a selectively transparent film formed by laminating a combination of a metal thin film layer and a high refractive index antireflection layer. The present invention was achieved based on the discovery that durability can be greatly improved by providing a barrier layer with a smaller refractive index than the antireflection layer in contact with the metal layer. That is, the present invention provides a laminate in which a selective light transmitting film formed by laminating a combination of a metal thin film layer (A) and a high refractive index antireflection layer (B) is provided on a transparent molded substrate. Barrier layer with at least one membrane (C)
, the barrier layer (C) exhibits a lower argon ion etching rate than the high refractive index antireflection layer (B), and the metal layer (A) is nth This is a laminate characterized in that it is the n+1th layer when . The gold layer used for the metal thin film layer (A) in the present invention may be any metal (including alloys) with low absorption loss in the visible light region, such as gold, silver, copper, aluminum, Palladium or an alloy thereof is preferably used. Examples of alloys include those containing 0.1 to 30% by weight of copper, preferably 0.3 to 15% by weight of silver;
The addition of copper can significantly improve the light resistance of silver thin films. Also, an alloy containing 3 to 30% by weight of gold in silver is also preferred as it improves the heat resistance of silver. Thus, the most preferred alloys are silver-copper-gold based alloys. The thickness of the metal thin film layer (A) is 50 to 300 Å, preferably 70 to 200 Å; if it is too thin, the infrared reflectance and heat resistance will be too low, and if it is too thick, the visible light transmittance will be too low. As a method for forming the metal thin film layer (A), a conventionally known physical paper deposition method can be applied. The high refractive index antireflection layer (B) is a layer of oxide of one or more metals selected from, for example, titanium, indium, zinc, tin, yttrium, erbium zirconium, cerium, tantalum, and hafnium. These are transparent to visible light and have a high refractive index in visible light, especially those with a refractive index of 1.6 or more.
1.8 or more is preferable. The film thickness of the high refractive index antireflection layer (B) is 50 to 500 Å, preferably 150 to 400 Å. Outside this range, visible light transmittance decreases. The high refractive index antireflection layer (B) can be provided by methods such as vacuum deposition, ion plating, sputtering, and wet coating. In the case of the wet coating method, for example, titanium oxide or zirconium oxide films formed from organic titanium compounds or organic zirconium compounds and containing 0.1 to 5% by weight of organic groups can also be used as antireflection films, and have the advantage of high productivity. have. In addition, the barrier layer (C) is made of an oxide of one or more metals selected from titanium, indium, zinc, tin, yttrium, erbium, zirconium, cerium, tantalum, hafnium, etc., or a combination of the metal oxide and the metal. The argon ion etching rate is lower than that of the high refractive index antireflection layer (B). The ratio of argon ion etching rates between the barrier layer (C) and the high refractive index antireflection layer (B) must be less than 1.0, usually less than 0.6, more preferably less than 0.4. A film having a low argon ion etching rate constituting the barrier layer (C) can be formed by adjusting the degree of oxidation of the film. For example, when using the sputtering method, it can be obtained by adjusting the composition of the target, the composition of the atmospheric gas during film formation, etc. As shown in the examples below, for example
Ar (95%) when using Ti, TiO targets
A good film can be obtained even with an atmosphere gas of +O ₂ (5%), but a good film cannot be obtained with a TiO ₂ target even with Ar (100%). Also in TiO target
Under the conditions of Ar (60%) + O ₂ (40%), the etching rate increases and a good film cannot be obtained. That is, by selecting the film forming conditions so that the degree of oxidation of the film is low, a good barrier layer (C) can be obtained. The thickness of the barrier layer (C) is 100 Å, preferably 80 Å or less; if it is too thick, the visible light transmittance will decrease. In the present invention, the barrier layer (C) can also be present in contact with the lower side of the metal thin film layer (A), in which case the metal thin film layer (A) is sandwiched between the barrier layer (C) in a sandwich pattern. It will happen. In such a configuration,
It is desirable that the total thickness of the barrier layer (C) is 140 Å or less in total. As the transparent molded base material used in the present invention, for example, a transparent sheet-like base material is suitable, and such transparent sheet-like base materials include, for example, polyethylene terephthalate resin, polyethylene naphthalate resin, polycarbonate resin, acrylic resin,
ABS resin, polystyrene resin, polyacetal resin, polyethylene resin, polypropylene resin,
Thermoplastic resins such as polyamide resins and fluororesins, thermosetting resins such as epoxy resins, sialyl phthalate resins, phenolic resins, and urea resins, as well as polyvinyl alcohol, polyacrylonitrile, polyurethane, aromatics, and polyamides. Examples include sheet-shaped molded products such as solvent-soluble resins such as polyimide resins. These may be used alone or as a mixture of two or more as homopolymers or copolymers. Inorganic molded products include glass such as soda glass, borosilicate glass, and silicate glass, metal oxides such as alumina, magnesia, zirconia, and silica, compound semiconductors such as gallium-arsenic, indium-phosphorous, and silicon. , molded products of semiconductors such as germanium. Note that the thickness of the sheet-like base material is not particularly limited,
It represents a wide range of contents, from so-called plate-like objects to film-like objects. In the present invention, the argon ion etching rate was measured as follows unless otherwise specified. (1) Equipment ESCA equipment manufactured by JEOL Ltd. (JESCA-
4) (Ion gun 931-2043 manufactured by Balyan Co., Ltd.) (2) Measurement method High refractive index anti-reflection layer (B ₁ ) and metal layer on the substrate
A laminate in which (A), a barrier layer (C), and a high refractive index antireflection layer (B ₂ ) are provided in the stated order will be described. Four substrates are prepared, and all of the above layers are formed on one substrate (1). In each step of forming layers (B ₁ ), (C) and (B ₂ ) on the substrate (1), the remaining 3
Under exactly the same conditions as when the layers (B ₁ ), (C) and (B ₂ ) are respectively formed on the substrate (1) by placing the substrates (2), (3) and (4) side by side. Layer (B ₁ )′ on substrate (2),
A layer (C)' is formed on the substrate (3), and a layer (B ₂ )' is further formed on the substrate (4). Thus, the following four types (i) Substrate (1)/layer (B ₁ )/layer (A)/layer (C)/layer (B ₂ ) (ii) Substrate (2)/layer (B ₁ )′ (iii) Substrate (3)/layer (C)′ (iv) Create a sample of substrate (4)/layer (B ₂ )′. Samples (ii), (iii) and (iv)
Determine the thickness of each layer on the substrate, then perform argon ion etching and determine the time it takes for each layer to be etched. The etching time for layer (C)/layer (B ₂ ) on substrate (1) is the same as that for substrate (3) and substrate (4).
This corresponds to the sum of the etching times determined for each of the upper layers. The etching rate is the layer thickness (Å) divided by the etching time (minutes) (Å/min). (3) Etching conditions and ESCA measurement conditions Etching conditions: Argon 2×10 ^-4 Torr (back pressure 5×10 ^-7 Torr) Argon incident angle 45°, emission current 25
mA, sample current 15μA, beam energy
2.75KV ESCA measurement conditions: X-ray target Mg Emission current 50mA Applied voltage 9KV Photoelectron analysis Detector voltage 3KV Step width 0.30V Step time 0.1 seconds Integration number 80 times Vacuum degree 5×10 ^-8 Torr In the present invention, selective light transmitting membrane It is unclear why it is effective to provide a layer (barrier layer) with a lower argon ion etching rate in contact with the metal layer than a high refractive index antireflection layer to improve environmental stability. No, but
This is probably related to the fact that the argon ion etching rate is a characteristic that reflects structural factors such as layer honeyness and polarity. The present invention will be described in more detail below using Examples. Examples 1 to 7, Comparative Examples 1 to 3 Titanium oxide thin film layer (B) with a thickness of 200 Å on a biaxially stretched polyethylene terephthalate film with a light transmittance of 86% and a thickness of 50 μm, and an alloy of silver and copper with a thickness of 150 Å A thin film layer (A) consisting of (92% by weight silver, 8% by weight copper),
A barrier layer (C) and a titanium oxide thin film layer (B) having a thickness of 200 Å were sequentially laminated to obtain a selectively transparent laminate. The titanium oxide thin film layer is made of 3 parts of tetramer of tetrabutyl titanate and 97% of isopropyl alcohol.
Apply a solution consisting of
Heat and set for a minute. The silver-copper alloy layer was formed by direct current sputtering targeting a silver-copper alloy (92% by weight silver, 8% by weight copper). Table 1 shows the method for manufacturing the barrier layer, the thickness of the barrier layer, the visible light transmittance and the infrared light (10μ) reflectance of the selective light transmitting laminate. Table 2 shows the barrier layer etching rate and the ratio of the barrier layer etching rate to the high refractive index antireflection layer of the selectively transparent laminate according to the method of the present invention,
In addition, a thermal deterioration acceleration test was performed by placing the selective light transmitting laminate in a hot air dryer set at 90°, and the time required for the infrared light (10 μ) reflectance to reach 85% of the initial value was measured. This is defined as the deterioration time. Comparative examples are also shown.

【table】

[Table] From Table 2, the effects of the present invention are clear. Examples 8 to 11, Comparative Examples 4 and 5 In the same manner as in Example 1, barrier layers (C) were provided on both sides of the thin film layer (A) made of an alloy of silver and copper, and the characteristics were evaluated. The results are shown in Table-3. The under barrier and top barrier were fabricated using the same method.

[Table] Example 12, Comparative Example 6 In the method of Example 1, titanium oxide thin film layer (B)
Instead, a zirconium oxide thin film layer (B) is laminated,
Further, as a barrier layer (C), RF sputtering was performed using Zr as a target instead of Ti, and the layer was laminated to obtain a light selectively transmitting laminate. The structure of the laminate is polyethylene terephthalate film\zirconium oxide thin film layer (B) (200Å)
\Silver-copper alloy layer (A) (150Å) \Barrier layer (C) (30
Å)\Zirconium oxide thin film layer (B) (200 Å). Here, the zirconium oxide thin film layer was coated with a solution consisting of 3 parts of tetrabutyl zirconate and 97 parts of isopropyl alcohol using a bar coater, and
Heat and set for a minute. The etching rate of the laminate with argon ions was measured by quantifying the amount of zirconium remaining in the laminate using a fluorescent X-ray method after etching for a certain period of time. The intensity of the ZrKa line before etching is set to 1.0,
Figure 1 shows the relative intensity of ZrKa lines in the laminate after argon ion etching for various times. Furthermore, a laminate without the barrier layer (C) was produced in the same manner. Argon ion etching of the laminate is also shown as Comparative Example 6. The area shown in FIG. 3 shows etching of the zirconium oxide thin film layer (B) in both Comparative Example 6 and Example 12. In Example 12, the region indicates the barrier layer (C), and the region indicates the silver-copper alloy layer. In Comparative Example 6, the area indicates a silver-copper alloy layer. From this, it can be seen that the average etching rates of the zirconium oxide thin film layer (B) and the barrier layer (C) by argon ions are 11 Å/min and 2.0 Å/min, respectively, and the barrier layer etching rate is smaller. Table of visible light transmittance, infrared light reflectance, and deterioration time.
4.

【table】 [Brief explanation of the drawing]

Figure 1 is a diagram showing the etching speed.

Claims (1)

[Scope of Claims] 1. In a laminate in which a selective light transmitting film formed by laminating a combination of a metal thin film layer (A) and a high refractive index antireflection layer (B) is provided on a transparent molded substrate, the light-transmissive film has at least one barrier layer (C), the barrier layer (C) exhibiting a lower argon ion etching rate than the high refractive index antireflection layer (B);
A laminate characterized in that the metal layer (A) is the n+1th layer when the metal layer (A) is the nth layer based on the transparent molded substrate. 2 The barrier layer (C) and the high refractive index antireflection layer
The ratio of argon ion etching rate to (B) is 0.6.
The laminate according to claim 1, which is as follows.