JP2009103936A - Light control mirror improved in durability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light control mirror improved in durability with respect to the repetition of switching. <P>SOLUTION: The light control mirror is made transparent by being exposed into an atmosphere containing hydrogen and is made into a metal state by being exposed into an atmosphere containing oxygen. The light control mirror thin film material is characterized in that a light reflection switchable layer is formed on a transparent substrate, a catalyst layer is formed thereon and further, a protective film is applied thereon. As the protective film, metal alkoxide or Teflon (R) is applied on the catalyst layer. The light control mirror thin film material is improved in visible light transmittance in the transparent state and is provided with diffusivity of light in the transparent state by the application of the protective film. The light control mirror member comprises including the above light control mirror thin film material as a component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light-reflective dimming mirror that can be switched between a transparent state and a mirror state. More specifically, the present invention automatically applies sunlight incident from a window glass without a blind or a curtain. The present invention relates to a new light control mirror thin film material used for a light control glass to be controlled and the light control mirror member. The present invention provides a light control mirror with improved durability, which is useful as a window material technology for controlling the transmittance of sunlight in buildings and vehicles.

  In general, windows (openings) in buildings are places where large heat enters and exits. For example, the rate at which heat is lost from the windows during winter heating is about 48%, and the rate at which heat enters from the windows during summer cooling is about 71%. Therefore, enormous energy saving effect can be obtained by controlling light and heat in the window. The light control glass has been developed for such a purpose and has a function of controlling inflow and outflow of light and heat.

  There are several types of light control methods for such light control glass. Among them, 1) a material whose transmittance is reversibly changed by application of current and voltage is called an electrochromic material. 2) A material whose transmittance is changed by controlling the atmospheric gas is referred to as a gas chromic material. Among them, research on electrochromic light control glass using a tungsten oxide thin film as a light control layer is most advanced, and it has almost reached the stage of practical use, and a commercial product is also available.

  The electrochromic light control glass known so far, including this tungsten oxide, is based on the principle that light control is performed by absorbing light in the light control layer. In this case, this type of light control glass has the disadvantage that the light control layer has heat by absorbing light and is re-radiated indoors, so that the energy saving effect is reduced. In order to eliminate this, it is necessary not to perform light control by absorbing light, but to use a light reflection type that performs light control by reflecting light. That is, a material having such a property that the state of the mirror and the transparent state reversibly change has been desired.

  Such a material that changes between a mirror state and a transparent state has not been found for a long time, but in 1996, a Dutch research group found that rare earth hydrides such as yttrium and lanthanum became transparent with a mirror state by hydrogen. It has been discovered that such a material changes to a new state, and such a material has been named “light control mirror” (Non-patent Document 1). These rare earth hydrides have a large change in transmittance and are excellent in light control mirror characteristics. However, since this light control mirror uses rare earth elements as a material, there are problems in resources and costs when used for window coating and the like.

  Subsequently, it was discovered that rare earth metal and magnesium alloy thin film hydrides (Non-patent Document 2) and magnesium-nickel alloy hydrides (Non-patent Document 3) also have dimming mirror characteristics. In the group of the present inventors, it has been found that MgNix (0.1 <x <0.3), which has a large magnesium component among magnesium / nickel alloys, exhibits excellent optical properties (Non-patent Document 4). Further, it has been found that when a magnesium-titanium alloy is used, it can be almost completely colorless when transparent.

  Thus, the dimming mirror materials reported so far include hydrides of rare earth metals such as yttrium and lanthanum, hydrides of rare earth metal and magnesium alloy thin films, and hydrides of magnesium / transition metal alloys. However, among these, magnesium / nickel alloys and magnesium / titanium alloys are suitable for window glass coating from the viewpoint of resources and cost.

  Any of these light control mirror thin film materials becomes transparent by hydrogenation when exposed to an atmosphere containing hydrogen, and returns to a metal state by dehydrogenation when exposed to an atmosphere containing oxygen. However, although all materials show good switching characteristics at the beginning, they show deterioration that gradually stops switching with repetition. Deterioration of this light control mirror material is fast, and most of the materials will deteriorate in about 100 times regardless of which material is used. This was the biggest obstacle to practical use.

J. et al. N. Huberts, R.A. Griessen, J. et al. H. Rector, R.D. J. et al. Wijngaarden, J. et al. P. Dekker, D.M. G. de Groot, N.M. J. et al. Koeman, Nature, 380 (1996) 231 Nagengast D.G. G, van Gogh A.G. T.A. M, Kooij E .; S, Dam B, Griessen R.M. Appl. Phys. Lett. , 75 (1999) 2050 T.A. J. et al. Richardson, J. et al. L. Slack, R.M. D. Armitage, R.M. Kostecki, B.M. Farangis, and M.M. D. Rubin, Appl. Phys. Lett. , 78 (2001) 3047 K. Yoshimura, Y. et al. Yamada and M.M. Okada: Appl. Phys. Lett. , 81 (2002) 4709

  In such a situation, the present inventors, in view of the above-mentioned prior art, with the goal of improving the durability against repeated switching and developing a dimming mirror material, working on improving the durability, As a result of repeated research, it was found that by forming a protective film on the surface of the dimming mirror thin film, it was possible to dramatically improve the durability against repeated switching. It has also been found that the transmittance of visible light can be improved, and the present invention has been completed.

  An object of the present invention is to provide a dimming mirror having improved durability against repeated switching by forming a protective film on the surface of the dimming mirror thin film material by a simple method. Another object of the present invention is to provide a dimming mirror having a visible light transmittance increased in a transparent state by the formation of the protective film.

The present invention for solving the above-described problems comprises the following technical means.
(1) In a light-reflective dimming mirror that becomes transparent by being exposed to an atmosphere containing hydrogen and becomes a metal state by being exposed to an atmosphere containing oxygen, a reflective dimming layer formed on a transparent substrate; A light control mirror thin film material comprising: a catalyst layer formed thereon; and a protective film formed thereon.
(2) The light control mirror thin film material according to (1), wherein the reflective light control layer is a thin film of any one of a rare earth metal, an alloy of rare earth metal and magnesium, and an alloy of magnesium and transition metal.
(3) The light control mirror thin film material according to (1), wherein the surface of the thin film is coated with 0.5 to 100 nm of palladium or platinum as a catalyst layer.
(4) The light control mirror thin film material according to (1) above, which has a thin metal film buffer layer between the reflective light control layer and the catalyst layer.
(5) The light control mirror thin film material according to (1), wherein a metal alkoxide or Teflon is applied on the catalyst layer as the protective film.
(6) The light control mirror thin film material according to (1), wherein the visible light transmittance in a transparent state is improved by the protective film.
(7) The light control mirror thin film material according to (1), wherein the protective film provides light diffusibility in a transparent state.
(8) A light control mirror member comprising the light control mirror thin film material according to any one of (1) to (7) as a constituent element.

Next, the present invention will be described in more detail.
The present invention is a dimming mirror thin film material, which is a dimming mirror that becomes transparent when exposed to an atmosphere containing hydrogen and becomes a metal state when exposed to an atmosphere containing oxygen, on a transparent substrate. A reflection light control layer, a catalyst layer is formed thereon, and a protective film is further applied and formed thereon.

  In the present invention, the reflective dimming layer is a thin film of any one of a rare earth metal, an alloy of rare earth metal and magnesium, an alloy of magnesium and transition metal, and 0.5 nm-100 nm as a catalyst layer on the surface of the thin film. In the preferred embodiment, palladium or platinum is coated and a metal alkoxide or Teflon (registered trademark) is applied on the catalyst layer as the protective film.

  Further, in the present invention, having a thin metal film buffer layer between the reflection light control layer and the catalyst layer, the protective film has improved the visible light transmittance in a transparent state, the protective film, It is preferable to have light diffusibility in a transparent state, and the present invention is characterized in that the light control mirror member includes the light control mirror thin film material as a constituent element.

  The present invention relates to a protective film coating of a dimming mirror (Switchable Mirror). The light control mirror is a material that can be switched between a transparent state and a mirror state (metal state) or an intermediate state thereof. A rare earth thin film (special table) such as yttrium or lanthanum is formed on a transparent substrate. No. 10-503858), rare earth metal and magnesium alloy thin film (Japanese Patent Publication No. 11-514759), magnesium and transition metal alloy thin film (US 2002 / 0044717A1), or magnesium thin film (Japanese Patent Laid-Open No. 2003-261356). And JP-A-2003-335553) are vapor-deposited.

  Among these materials, MgNix (0.1 <x <0.3) is a suitable material for the light control mirror because of its low material cost and excellent optical characteristics. These light control thin film layers can be produced by sputtering, vacuum deposition, electron beam deposition, chemical vapor deposition (CVD), plating, or the like. However, it is not limited to these methods. The thickness of the light control thin film layer is 10 nm to 300 nm.

  A catalyst layer is formed on the light control thin film layer. As the catalyst layer, palladium or platinum is preferably used. However, it is not limited to these, and can be used similarly if they have the same effect. This catalyst layer is preferably formed by coating palladium or platinum of 0.5 nm to 10 nm on the surface of the magnesium thin film. However, the formation method and form of the catalyst layer are not particularly limited.

  The catalyst layer can be produced by sputtering, vacuum vapor deposition, electron beam vapor deposition, chemical vapor deposition (CVD), plating, or the like. However, it is not limited to these methods. A light control mirror member or light control mirror glass is obtained by forming a light control layer made of the light control mirror material on the transparent member or glass surface of the substrate. In this case, the substrate is preferably exemplified by acrylic, plastic, transparent sheet, and glass. However, the present invention is not limited to these and can be used in the same manner as long as they have the same effect.

  When this light control mirror is exposed to an atmosphere containing hydrogen, hydrogenation occurs and the metal mirror changes to a transparent state. In addition, dehydrogenation occurs by exposure to an atmosphere containing oxygen but not hydrogen, and changes from a transparent state to a metallic state. Whichever light control mirror thin film material is used, good switching is exhibited at first and a large change in transmittance is exhibited. However, when this is repeated, deterioration occurs and the change gradually stops. As a result of investigating the cause of the deterioration, one is that magnesium under the palladium layer is deposited on the surface by repeated switching, and the other is expansion of the thin film due to repeated hydrogenation and dehydrogenation. -It was found that there are two factors that cause the thin film to break due to repeated shrinkage.

  Regarding the former deposition on the surface of magnesium, it was found that it is effective to insert a thin metal film such as titanium as a buffer layer between the palladium layer and the magnesium alloy layer (Japanese Patent Application No. 2006-130939). . However, even if a buffer layer is inserted, degradation still occurs due to the effects of expansion and contraction. However, the present inventors applied a protective film on the surface of palladium to suppress the influence and tolerate repeated switching. The present inventors have found that the properties can be dramatically improved, and have reached the present invention.

  When a metal alkoxide or Teflon (registered trademark) is applied as a protective film on the catalyst layer of the light control mirror, the deterioration can be greatly suppressed and the repeated life for switching can be extended. The application of these protective films is preferably performed using a spin coating method, a dip coating method, or sputtering, but the method is not particularly limited. Preferred examples of the metal alkoxide include titanium alkoxide, vanadium alkoxide, aluminum alkoxide and the like.

In the dimming mirror, it is desirable that the visible light transmittance when transparent is high, but the thin film in a hydrogenated state also has some absorption, so even when Mg ₆ Ni having a relatively high visible light transmittance is used. The transmittance of visible light is about 50%.

  On the other hand, it was found that when a metal alkoxide or Teflon (registered trademark) was applied as a protective film, the visible light transmittance in a transparent state was improved by about 10%. This is considered that the transmittance in the visible light region is improved by the interference effect of the multilayer thin film. Therefore, the application of these protective films provides a double merit that durability is improved and transmittance in a transparent state is improved.

  However, when this dimming mirror is used in a building, there is a problem that the sun or the like is reflected and dazzled if the mirror is too clear. In order to solve this, light may be scattered in the reflection state. By creating such a diffusive reflective surface, the reflected glass appears whitish, and the phenomenon of dazzling sunlight and the like is suppressed. It has been found that when a metal alkoxide, which is one of the materials used as a protective film in the present invention, is applied, the surface diffuses light, resulting in a more whitish diffusivity.

  The light control mirror glass of this invention can be widely used not only for the said window material but for all kinds of members or articles. Thereby, for example, a dimming mirror function can be added to a shielding object for the purpose of privacy protection, a decorative object using a change from a mirror state to a transparent state, a toy, and the like. In the present invention, an article having a light control mirror function is defined as including all kinds of goods equipped with the light control mirror glass.

The present invention has the following effects.
(1) The durability against switching can be greatly improved by applying a protective film to the light control mirror.
(2) Moreover, the transmittance | permeability in the transparent state of a light control mirror can be made high by apply | coating the said protective film.
(3) It is possible to provide a highly durable dimming mirror that dramatically increases the durability against repeated switching and has an increased transmittance.
(4) According to the present invention, the application of the protective film provides the double advantage of improved durability and improved transmittance in a transparent state.
(5) Also, by applying the protective film, light diffusibility can be imparted in a transparent state.

  Next, the present invention will be described casually based on examples, but the present invention is not limited to the following examples.

  In this example, a light control mirror thin film material was produced. As reference samples, a glass substrate without a buffer layer and a magnesium / nickel alloy-based dimming mirror thin film in which the buffer layer was inserted were prepared. These films were formed by a quadruple magnetron sputtering apparatus in which metallic magnesium, metallic nickel, metallic titanium, and metallic palladium were set as targets. As a substrate, a glass plate having a size of 30 mm × 30 mm and a thickness of 1 mm was used. After cleaning this, it was set in a vacuum apparatus and evacuated.

In film formation, first, a magnesium / nickel thin film was produced by simultaneously sputtering a magnesium and nickel target. The argon gas pressure during sputtering was 0.8 Pa, and sputtering was performed by applying a power of 30 W to magnesium and 11 W to nickel by direct current sputtering to produce an alloy thin film having a composition almost similar to Mg ₄ Ni.

One sample was subjected to vapor deposition of a palladium thin film under the same vacuum condition by applying 6 W power. The thickness of the Mg ₄ Ni layer is about 40 nm, and the thickness of the palladium layer is about 4 nm. As another sample, after depositing Mg ₄ Ni, a 45 W power was applied to deposit a titanium thin film, and then a 6 W power was applied to deposit a palladium thin film. The thickness of the Mg ₄ Ni layer is about 40 nm, the thickness of the titanium layer is about 2 nm, and the thickness of the palladium layer is about 4 nm.

The switching characteristics of these samples were evaluated using an apparatus as shown in FIG. The other glass and silicon rubber spacers are bonded together so that the Pd / Mg ₄ Ni thin film produced on the glass is on the inside, and hydrogen gas diluted to 4% with argon flows in the space between them, Switching was performed by stopping.

The Pd / Mg ₄ Ni thin film (without protective film) immediately after deposition uses a metallic luster and is in a mirror state, but when a hydrogen gas is flowed, it changes to a transparent state in a few seconds. When hydrogen gas is stopped, air enters from the end face and returns to the mirror state in 2-3 minutes. The change in transmittance at a wavelength of 670 nm at this time was measured using a semiconductor laser and a silicon photodiode. FIG. 1B shows a photograph of the measuring device.

2 (a) and 2 (b) show the durability of switching between the Pd / Mg ₄ Ni thin film without the buffer layer and the Pd / Ti / Mg ₄ Ni thin film with the buffer layer, as measured by this evaluation apparatus. Show. When there is no buffer layer, the deterioration is quick, the change width gradually decreases with repeated switching, and the change width becomes very small after about 170 times. On the other hand, the sample in which the titanium buffer layer is inserted does not show any deterioration until about 300 times, but then deteriorates rapidly.

In this example, a sample in which a protective film was applied to the light control mirror sample produced in Example 1 was produced. That is, in order to suppress deterioration, a sample in which the alkoxide was applied to the surface of the sample Pd / Ti / Mg ₄ Ni prepared in Example 1 was prepared. As the alkoxide solution, 1.5 ml of Titanium tetrapropoxide was taken and dissolved in 50 ml of a mixed solution of benzene and toluene (1: 1) so that the volume concentration was 3.0%.

This solution was applied by dip coating on a magnesium / nickel light control mirror thin film (Pd / Ti / Mg ₄ Ni) with a buffer layer prepared under the same conditions as in Example 1. The sample was pulled up at a rate of 2 cm / min in the solution to form a gel film in the air. The gel film was naturally dried at room temperature for 2 hours, and further dried at 60 ° C. for 1 hour to remove organic substances.

  FIG. 2C shows the change in transmittance when this sample is switched. Compared with the case where the protective film of Example 1 is not provided, the durability against switching is greatly improved, and almost no deterioration occurs until around 1700 times.

  FIG. 3 shows the change in optical transmittance with respect to time, and the sample with the protective film changes from the metallic state to the transparent state and the sample without the protective film. It can be seen that there is no significant difference in the reaction time from the transparent state to the metal state, and the transmittance when it becomes transparent is increased by about 10%.

  Thus, the application of the protective film using the metal alkoxide improves the durability and increases the transmittance when transparent. FIG. 4 shows the state of reflection in a metal state between a sample without a protective film and a sample with a metal alkoxide protective film. It can be seen that the sample without the protective film is close to the mirror and reflects the near one well, whereas the sample with the protective film is whitish due to surface diffusion.

An example in which Teflon (registered trademark) is coated as a material for suppressing deterioration will be described. The original sample was the same as the sample Pd / Ti / Mg ₄ Ni produced in Example 1, and the surface was coated with a thin film of Teflon (registered trademark) using a sputtering apparatus. A Teflon (registered trademark) plate having a diameter of 50 mm and a thickness of 1 mm is fixed on a copper substrate with an adhesive, and argon gas and CF ₄ gas are used as a target so that the pressure is 0.73 Pa at a flow ratio of 10: 1. Was sputtered at about 30 W.

  A Teflon (registered trademark) film having a thickness of about 1 μm was obtained by sputtering for 40 minutes. FIG. 5 shows durability regarding switching of a sample coated with the Teflon (registered trademark) protective film. Compared to the case without the protective film (FIGS. 2A and 2B), it can be seen that the durability is significantly improved and switching is possible up to about 1500 times.

  As described above in detail, the present invention relates to a light control mirror with improved durability. By applying a protective film to the light control mirror according to the present invention, the durability is greatly improved. At the same time, it is possible to provide a light control mirror having improved transmittance in a transparent state. According to the present invention, it is possible to provide a light control mirror that improves the visible light transmittance in a transparent state and has light diffusibility by applying the protective film. INDUSTRIAL APPLICATION This invention is useful as what provides the new technique and new product which enabled realization of the light control mirror which improved the durability with respect to the repetition of switching dramatically.

FIG. 1 is a schematic diagram of a dimming mirror characteristic evaluation apparatus. (A) is a schematic diagram, (b) is a photograph. FIG. 2 shows the durability against switching of the Mg—Ni dimming mirror. (A) No buffer layer, no protective film, (b) With a buffer layer, no protective film, (c) With a buffer layer, with a protective film. FIG. 3 shows the switching characteristics of a sample without a protective film and a sample coated with an alkoxide protective film. FIG. 4 shows the appearance of a sample without a protective film (left) and a sample coated with alkoxide as a protective film (right). FIG. 5 shows the durability against switching of a sample with a Teflon (registered trademark) protective film.

Claims (8)

  In a light reflective dimming mirror that becomes transparent when exposed to an atmosphere containing hydrogen and becomes a metal state when exposed to an atmosphere containing oxygen, a reflective dimming layer formed on a transparent substrate, A light control mirror thin film material comprising: a formed catalyst layer; and a protective film formed thereon.   The light control mirror thin film material according to claim 1, wherein the reflection light control layer is a thin film of any one of a rare earth metal, an alloy of rare earth metal and magnesium, and an alloy of magnesium and transition metal.   The light control mirror thin film material according to claim 1, wherein the surface of the thin film is coated with 0.5 nm to 100 nm of palladium or platinum as a catalyst layer.   The light control mirror thin film material according to claim 1, further comprising a thin metal film buffer layer between the reflection light control layer and the catalyst layer.   The light control mirror thin film material according to claim 1, wherein a metal alkoxide or Teflon is applied on the catalyst layer as the protective film.   The light control mirror thin film material according to claim 1, wherein the visible light transmittance in a transparent state is improved by the protective film.   The light control mirror thin film material according to claim 1, wherein the protective film provides light diffusibility in a transparent state.   A light control mirror member comprising the light control mirror thin film material according to claim 1 as a constituent element.