JP2005084261A - Optical thin film, display device using the same, and method for generating image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical thin film which varies its transmissivity reversibly by ultraviolet ray irradiation and visible ray irradiation, is large in variation width and has a high transmissivity and a low haze, and to provide an optical thin film which can be manufactured through a simple process. <P>SOLUTION: The optical thin film is formed of particles consisting principally of silver which has a specified particle size, an inter-particle distance, and particle number density an an element selected out of titanium, zirconium, vanadium, niobium, tantalum, chrome, molybdenum, tungsten, manganese, silicon, germanium, phosphorus, and oxygen. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical thin film whose optical characteristics can be controlled by light irradiation.

  Research has been conducted on materials whose transmittance and color change reversibly by light. For example, materials that are highly transparent and have low haze in the initial state, but whose transmittance can be reduced by UV irradiation, and that can be made highly transparent again by visible light irradiation, are frequently studied. ing.

In addition, a material for depositing silver nanoparticles on the surface of the titanium oxide film has been reported. (Reference literature The 82nd Annual Meeting of Chemical Society of Japan (2C1-14), p142 (2002) (non-patent literature 1), nature materials, vol.2, January, 29-31 (2003) (non-patent literature) 2)).
Specifically, a thin film obtained by dispersing a solution containing Ag ions on a titanium oxide film obtained by applying a suspension of titanium oxide particles on a substrate and drying it is irradiated with ultraviolet rays. It has been reported that the transmittance is lowered and the transmittance is increased again by irradiating with visible light, and this phenomenon is repeatedly exhibited.

  By the way, when using the technique of dispersing a solution containing silver ions on the surface of a titanium oxide film obtained from a titanium oxide suspension that has been reported so far, the change in transmittance of the material due to ultraviolet irradiation or visible light irradiation. There were problems that the width was narrow, the initial transmittance was low, and the haze value was high.

Further, it is generally known that a thin film produced by a wet method has a large variation in characteristics such as a film thickness, and the tendency becomes remarkable as the size and area of the thin film increase. For this reason, silver nanoparticles produced by dispersion of a solution containing Ag ions have a large variation in characteristics, and there is a problem that the photochromic function to be expressed is difficult to control. Therefore, it is said that it is difficult to apply it to display applications that require uniformity. Furthermore, since the manufacturing process is multi-stage, it is difficult to control performance and quality, and there is a problem in application to industrialization.
Proceedings of the 82nd Annual Meeting of the Chemical Society of Japan (2C1-14), p. 142 (2002) nature materials, vol.2, January, 29-31 (2003)

  Therefore, the problem to be solved by the present invention is that the change in transmittance due to ultraviolet irradiation and visible light irradiation is larger than that of the prior art, high transmittance and low haze, and the transmittance is reversible by light irradiation. It is to provide a changing optical thin film. Another object of the present invention is to provide an optical thin film that can be produced by a simple process.

The present inventors have studied to solve the above problems. As a result, any silver particle having a specific particle diameter and interparticle distance and any one selected from titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, silicon, germanium, phosphorus, and oxygen. The present inventors have found that an optical thin film composed of any of these elements can solve the above-described problems, and have completed the present invention. That is, the present invention
(1) A thin film containing silver and at least one element selected from titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, silicon, germanium, phosphorus, and oxygen,
(I) containing particles containing silver as a main component,
(II) The ratio of the number of particles (Ag-2) containing silver having a diameter of 0.5 to 50 nm as a main component to the number of particles (Ag-1) containing silver having a diameter of 0.5 nm to 1 mm as a main component is 50-100%,
(III) The number of silver particles (Ag-3) having a closest distance of 3 to 100 nm between particles mainly composed of silver having a diameter of 0.5 nm to 1 mm is 50 to 100 of the number of silver particles (Ag-1). %
(IV) The particle number density of particles mainly composed of silver having a diameter of 0.5 to 50 nm (Ag-2) is 5 × 10 ² to 2 × 10 ⁵ particles / μm ^2.
An optical thin film characterized in that
(2) Preferably, an optical thin film having a base layer made of a polymer material,
(3) Preferably, a step of forming at least particles (Ag-1);
Optical formed mainly by the step of forming a portion (base layer) composed of an element selected from titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, silicon, germanium, phosphorus, and oxygen. A thin film,
(4) Preferably, the optical layer is characterized in that the base layer has titanium and oxygen and has a diffraction peak at 2θ = 24 to 28 ° as an X-ray diffraction pattern by the θ-2θ method.
(5) Preferably, an optical thin film characterized in that the particles (Ag-1) are particles formed by a vacuum film formation method,
(6) Preferably, an optical thin film characterized in that the base layer is formed by a vacuum film formation method,
(7) A display device using the above optical thin film,
(8) A method of creating an image by irradiating the display device with a light beam and controlling the transmittance of the optical thin film.

  Since the optical thin film of the present invention has the above-described configuration, the change width of the transmittance due to ultraviolet irradiation and visible light irradiation is larger and reversibly changed than before, and the transmittance is low and the transmittance is low. It has the advantage of being haze. Moreover, since it can produce by a vacuum film-forming method, it can also enlarge and has the advantage that it can expand | deploy to a display use.

  The optical thin film of the present invention is characterized by having a film made of any element selected from silver and titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, silicon, germanium, phosphorus, and oxygen. To do. In addition, the optical thin film of the present invention is preferably partially or entirely obtained by a vacuum film forming method.

  The optical thin film in the present invention can be used alone, but it is preferable that the optical thin film is formed on a substrate in consideration of strength, handling and the like. For example, when the cross-sectional configuration is exemplified, the substrate / optical thin film is obtained.

  If the base | substrate used as needed in this invention is transparent and self-supporting, there will be no restriction | limiting in particular in the material and thickness. The material is generally polymer, glass, or metal.

  The polymer material is suitable because it provides a substrate that requires light weight and flexibility. Specific examples of the polymer material that can be used in the present invention include polyethylene terephthalate (PET), polycarbonate (PC), polyether sulfone (PES), polyimide, polysulfone (PSF), polymethyl methacrylate (PMMA), Examples include polyether ether ketone (PEEK), polypropylene (PP), and triacetyl cellulose (TAC). Of these, polyethylene terephthalate (PET) is particularly preferable.

  Examples of the glass that can be used in the present invention include soda glass, alkali glass, and quartz glass. These glasses may be tempered.

  A coating layer for the purpose of improving adhesion to the optical thin film layer, improving gas barrier properties, improving weather resistance, etc. may be present on the surface of the substrate.

  The thickness of the substrate is generally 10 μm to 10 cm. If it is too thin, the rigidity may be low and handling may be difficult. The thickness of the substrate is more preferably 25 μm to 1 cm, further preferably 50 μm to 1 mm.

The optical thin film in the present invention is a thin film having at least one element selected from titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, silicon, germanium, phosphorus, oxygen and silver,
(I) containing particles containing silver as a main component,
(II) The ratio of particles (Ag-2) containing silver having a diameter of 0.5 to 50 nm as a main component to the number of particles (Ag-1) containing silver having a diameter of 0.5 nm to 1 mm as a main component is 50 to 50 100%
(III) The number of silver particles (Ag-3) having a closest distance of 3 to 100 nm between particles mainly composed of silver having a diameter of 0.5 nm to 1 mm is 50 to 100 of the number of silver particles (Ag-1). %
(IV) Particle number density of particles (Ag-2) whose main component is silver having a diameter of 0.5 to 50 nm is 5 × 10 ² to 2 × 10 ⁵ particles / μm ^2.
It is characterized by being.

  The silver-based particles of the present invention preferably have a diameter of 1 mm or less, more preferably particles (Ag-1) having a diameter of 0.5 nm to 1 mm as a main component. preferable.

  The particle (Ag-2) of the present invention refers to a particle (Ag-1) having a diameter of 0.5 to 50 nm, and the number of particles (Ag-1) (Ag-1) ) To the number is 50 to 100%, preferably 70 to 100%, more preferably 90 to 100%. In addition, among the particles (Ag-1), it is more preferable that particles containing silver having a diameter of 0.5 to 40 nm as a main component are 70% or more of the number of particles (Ag-1). In addition, among the particles (Ag-1), it is more preferable that particles containing silver having a diameter of 0.5 to 30 nm as a main component are 70% or more of the number of particles (Ag-1).

  The particle (Ag-3) of the present invention refers to a particle (Ag-1) having a closest distance of 3 to 100 nm between the particles (Ag-3). 1) The ratio to the number is more preferably 70 to 100%, still more preferably 90 to 100%.

  80 to 100% of the composition of the silver-based particle according to the present invention is silver. Moreover, the shape is not limited to a spherical shape, but includes a distorted shape. The diameter of the distorted particle is defined by the maximum diameter within the particle.

The particle number density of the particles (Ag-2) is 5 × 10 ² to 2 × 10 ⁵ particles / μm ² . The particle number density of the above-mentioned particles (Ag-2) is preferably 5 × 10 ² to 1 × 10 ⁵ particles / μm ² , particularly preferably 5 × 10 ² to 5 × 10 ⁴ particles / μm ² . If the above density is too higher than the above range, the conditions relating to the closest distance between the silver particles necessary for the present invention may not be satisfied, and the function in the present invention may not be expressed. In some cases, the silver-based particles necessary for developing the function are insufficient, and the function in the present invention is not exhibited.

In the present invention, the above-mentioned particle number density of particles mainly composed of silver is obtained as follows. That is, using TEM or SEM, the number of particles mainly composed of silver existing in the range of 100 nm □ is examined, and the existence density per 1 μm ² is calculated. In an arbitrary total of 10 regions, the particle number density is obtained, and the average thereof is defined as the particle number density in the present invention.

  The silver-based particle is a layer (base layer) composed of at least one element selected from at least titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, silicon, germanium, phosphorus, and oxygen. It is preferable that it exists in the inside or surface of. Here, as the base layer, an oxide of at least one element selected from at least titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, silicon, germanium, and phosphorus is preferable.

  When the optical thin film of the present invention is applied to an application using the change in transmittance, it is desirable that the visible light transmittance of the base layer is as high as possible and the haze is as low as possible. Here, the visible light transmittance of the base layer is high and the haze is low. When the base layer having a thickness of 200 nm is formed on glass, the visible light transmittance is 70 to 100% and the haze value is 0 to 3%. Means. A more preferable visible light transmittance is 80 to 100%, still more preferably 90 to 100%. A preferable range of the haze value is 0 to 2%, and more preferably 0 to 1%.

  In order to realize this haze value, the base layer is preferably an aggregate of particles containing the above elements, and the diameter of the particles is preferably as small as possible, and is 0.5 to 100 nm. Is more preferable. More specifically, the ratio of the number of particles having a diameter of 0.5 to 50 nm is preferably 70% or more with respect to the number of particles having a diameter of 0.5 to 100 nm present in the base layer. More preferably, the ratio of the number of particles having a diameter of 0.5 to 40 nm is 70% or more, and still more preferably the ratio of the number of particles having a diameter of 0.5 to 30 nm is 70% or more.

  The base layer according to the present invention preferably has high crystallinity. Evaluation of crystallinity may be performed by a conventionally known means. For example, crystallinity can be evaluated from an X-ray diffraction pattern by the θ-2θ method.

  The base layer according to the present invention is particularly preferably titanium oxide. The titanium oxide preferably has a diffraction peak at 2θ = 24 to 28 ° as an X-ray diffraction pattern by the θ-2θ method.

  There is no specific designation for the thickness of the base layer. However, if the total of the base layers is too thick, cracking is likely to occur due to external stress and heat distortion, and it is difficult to obtain high uniformity in terms of light transmission, color, and the like. If it is too thin, the optical thin film in the present invention may be insufficient. Therefore, the total thickness of the base layer is preferably 10 nm to 3 μm. More preferably, it is 50 nm-1 micrometer, More preferably, it is 100 nm-500 nm.

  The optical thin film in the present invention comprises a substrate and an optical functional layer, and if necessary, a protective layer and an intermediate layer. The configuration of the optical functional layer is such that a group of particles containing silver as a main component is present near or inside the surface of the base layer. Here, the particle group mainly composed of silver is an aggregate of particles mainly composed of silver that satisfy the requirements (II) to (IV).

  Configuration examples of the optical functional layer and the optical thin film will be specifically described with reference to the drawings. 1 to 8 are sectional views of an optical thin film according to the present invention. In FIG. 1, a base layer 20 is formed on one main surface of a substrate 10, and particles 30 mainly composed of Ag exist in the vicinity of the surface of the base layer 20. In FIG. 2, for example, the base layer 20 and the particles 30 mainly composed of Ag are sequentially formed on one main surface of the substrate 10, and the base layer 20 is further formed thereon. In FIG. 3, for example, particles 30 mainly composed of Ag are formed on one main surface of the substrate 10, and the base layer 20 is formed thereon. In FIG. 4, particles 30 mainly composed of Ag are formed on the outermost base layer 20 of FIG. FIG. 5 shows a configuration in which a base layer 20 is further formed on the particle 30 side mainly composed of Ag in the configuration of FIG. FIG. 6 shows a structure in which particles 30 mainly composed of Ag are dispersed in the base layer 20. FIG. 7 shows a structure in which an optical thin film 40 composed of a base layer 20 and particles 30 containing Ag as a main component is formed on one main surface of a substrate 10, and a protective layer 50 is further formed thereon. is there. FIG. 8 shows a configuration in which an intermediate layer 60 is formed on one main surface of the substrate 10 and an optical thin film 40 is further formed thereon. FIG. 9 shows a configuration in which a protective layer 50 is formed on the optical thin film 40 of FIG.

  In the present invention, the silver-based particles are preferably produced by a vacuum film forming method. The vacuum film-forming method is a method in which a metal such as silver or a metal oxide used in the present invention is activated and fixed to an object by heat, gas, etc., but the amount of the metal or metal oxide is controlled to be low. The particles having a particle diameter of 1 to 50 nm (Ag-2) and the particles having a closest distance of 3 to 100 nm (Ag-3), which are requirements in the present invention, are formed without forming a film by a method such as It is possible.

  On the other hand, the conventionally reported wet method generally requires the present invention because silver particles easily grow to a particle size of 50 nm or more in the process and the particles easily come into contact with each other. It is very difficult to meet the requirements.

  There is no particular designation in the method for producing a base layer made of an element selected from titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, silicon, germanium, phosphorus, and oxygen according to the present invention. Some means can be used. Among these, it is preferable to prepare by a vacuum film forming method. In vacuum film formation, it is possible to achieve a constituent particle diameter of 1 to 50 nm, which is a preferable requirement in the present invention. Therefore, it is possible to obtain an optical thin film having a low haze as compared with a wet method in which the diameter of the constituent particles easily grows to 50 nm or more in the process. In particular, in the production process, in the case where it is necessary to form a base layer on a particle group containing Ag as a main component, it is preferable to form the base layer by a vacuum film forming method. For example, this corresponds to the case of realizing the configuration shown in FIGS.

  When a base layer is formed on a group of particles containing silver as a main component by a wet method, particles containing silver as a main component may diffuse unevenly into the base layer, resulting in a desired particle size and dispersion. It may be difficult to achieve density.

  In the case of a structure in which a group of particles mainly composed of Ag is dispersed inside the base layer, it is preferable to form the group of particles mainly composed of the base layer and Ag by a vacuum film forming method. For example, the configuration shown in FIG.

  In the case of forming by a wet method, it is sufficient to prepare a base layer component and a solution containing Ag as a main component and coat it on a substrate. It is generally difficult to do.

  Further, as described above, the total thickness of the base layer particularly suitable in the present invention is 10 nm to 3 μm. While it is extremely difficult to form a layer having the thickness with high thickness accuracy by a wet method, the vacuum film formation method capable of easily controlling the thickness accuracy is a means for forming the base layer in the present invention. Useful.

  When the change in transmittance of the optical thin film is utilized, the most suitable transmittance of the base layer is 90 to 100%, and the most suitable haze value is 0 to 1%. Usually, the particle diameter is often an aggregate of particles having a diameter of 50 nm or more, and it is often difficult to obtain the transmittance and haze value. In contrast, the vacuum film-forming method is useful as a method for forming a base layer in the present invention because it is easy to form a uniform layer without generating particle aggregates.

  As the vacuum film forming method, a conventionally known method can be used. For example, a vacuum heating deposition method, an ion beam deposition method, an ion plating method, a sputtering method, or a CVD method can be used.

  In the vacuum vapor deposition method, a desired metal can be used as a vapor deposition source, and a metal thin film can be easily formed by heat vapor deposition by resistance heating, electron beam heating, or the like. In the ion plating method, vacuum deposition is performed by resistance heating a desired metal or sintered body in a reactive gas plasma or by heating with an electron beam. In the sputtering method, a desired metal or sintered body is used as a target, an inert gas such as argon or neon is used as a sputtering gas, and a reactive gas is added as necessary to perform sputtering.

  It is preferable to take measures to increase the crystallinity during or after the formation of the base layer. For example, a method of heating the substrate before or at the time of film formation or heating after forming the base layer can be used. The temperature necessary for heating needs to be determined in consideration of the material of the base layer and necessary characteristics, but the heating temperature is usually 150 to 500 ° C. When heating the base material after film formation, it is preferable to consider the heating time, but the heating time is generally 10 seconds to 24 hours.

  When a polymer material is used as the substrate, it is preferable to obtain a highly crystalline base layer by a method other than heating because the polymer material is generally easily deformed by heat.

  In order to form a base layer with high crystallinity without heating, the number of particles incident on the substrate from an oblique direction may be reduced during film formation. For example, measures such as making the distance between the target substrates longer than usual or installing a shielding plate that is bulkier than usual around the target may be used.

  The protective layer employed as necessary in the present invention is a layer for protecting the optical functional layer from the atmosphere or external force, and a known material can be used without limitation. Specifically, commonly used antifouling materials, moisture proof materials, and hard coat materials can be used. More specifically, thin films such as titanium oxide, silicon oxide, zinc oxide, indium oxide, and tin oxide, and films such as acrylic resin, ethylene copolymer, and ethylene-vinyl alcohol copolymer can be used. The thickness of the protective layer is not particularly specified, and is determined in consideration of the material to be used, necessary protective ability, and light transmittance as necessary. Usually, it is 3 nm to 200 μm.

  The intermediate layer employed as necessary in the present invention is formed mainly for the purpose of improving the adhesion between the substrate and the optical functional layer, improving the function of the optical functional layer, and the like. There are no particular restrictions on the material. In general, titanium oxide, silicon oxide, zinc oxide, titanium, nickel, chromium, nickel chromium alloy or the like is used. The thickness of the intermediate layer is not particularly specified, and is determined in consideration of the material to be used, the necessary capacity, and the light transmittance as necessary. Usually, it is 3 nm to 10 μm.

  What is necessary is just to select the optimal light transmittance for a base | substrate, a protective layer, and an intermediate | middle layer with the use and usage method. If the application uses the change in light transmittance of the optical thin film, it is desirable that the light transmittance of the substrate and the optical thin film is high. For that purpose, it is desirable that the light transmittance of the substrate, the protective layer, and the intermediate layer is high. . Here, high light transmittance means that the transmittance at a wavelength of 550 nm is 60 to 100%. If the application uses the color change of the optical thin film itself, it is important to control the light transmittance of the layer located in the direction in which the color of the optical thin film is visually recognized. For applications that are visible from the protective layer side, it is desirable that the transparency of the protective layer is high, that is, the transmittance at a wavelength of 550 nm is preferably 60 to 100%. It is necessary that the light transmittance is high, and the protective layer is not necessarily required to have a high light transmittance. However, when viewing from both sides, it is natural that the protective layer, the intermediate layer, and the substrate each have high light transmittance.

  The optical thin film in the present invention changes its transmittance by receiving ultraviolet rays and visible rays. When the optical thin film immediately after film formation is exposed to ultraviolet rays, the transmittance decreases in any part of the visible light region or in the entire region. This state is referred to as state 1. Subsequent exposure to visible light increases its transmittance in any or all of the visible light region. This state is referred to as state 2. The optical thin film reaches state 1 when exposed to ultraviolet rays again, and reaches state 2 when exposed to visible light. As described above, the state can be reversibly changed to the state 1 and the state 2 by exposure to ultraviolet rays or visible light. The optical thin film according to the present invention is characterized in that the difference in transmittance (change in transmittance) between the state 1 and the state 2 is significantly larger than that in the prior art.

  Since the optical thin film of the present invention controls the particle size and distribution state of particles mainly composed of Ag, a preferable transmittance change amount between the state 1 and the state 2 is 6 to 60%, Preferably it is 10 to 60%, More preferably, it is 15 to 60%. More preferably, it is 20 to 60%, and this can be realized at a wavelength set according to the application. On the other hand, in the conventional wet method, the transmittance change amount is about 1 to 6% for light with a wavelength of 550 nm, and 5% or less for light with a wavelength of 650 nm. An extremely high transmittance difference can be realized.

  Moreover, the optical thin film of the present invention has high durability. Here, the durability is defined by the ratio of ΔT before and after the treatment by exposing the optical thin film to an environment at a temperature of 60 ° C. and a humidity of 90%, examining the transmittance difference ΔT between the state 1 and the state 2 before and after that. Specifically, the transmittance before processing is ΔTb, the transmittance after processing is ΔTa, and the larger ΔTa / ΔTb is, the higher the durability of the optical thin film in the present invention is. The durability ΔTa / ΔTb of the optical thin film of the present invention is preferably 0.3 to 1, and preferably 0.6 to 1.

In the present invention, the conditions for irradiating the optical thin film in the initial unirradiated state or in the state 2 with ultraviolet rays are as follows: the wavelength is 300 to 400 nm or the entire region, the intensity is 0.5 mWcm ⁻² or more, The time is 3 minutes or more. Moreover, the conditions at the time of irradiating visible light to the optical thin film in the state 1 are that the wavelength is either 400 to 800 nm or the entire region, the intensity is 10 mWcm ⁻² or more, and the time is 3 minutes or more. Here, as the intensity of light increases, the transmittance increases in a shorter time, and the state 1 is changed to the state 2. For example, if the light intensity is 50 mWcm ⁻² , the change from the state 1 to the state 2 is completed after about 30 minutes. If the light intensity is about 200 mWcm ⁻² , the change from the state 1 to the state 2 is completed after about 5 minutes.

  In the optical thin film of the present invention, the wavelength at which the transmittance increases after irradiation with visible light can be selected by controlling the wavelength of visible light exposed at the stage of state 1. Further, it is possible to select the shape of the transmission spectrum of the optical thin film in the state 1 by controlling the wavelength of the ultraviolet light that is exposed in the initial stage where the ultraviolet light or visible light is not irradiated or in the state 2 stage.

The optical thin film in the present invention can be used for a display material, a light shielding material and the like.
For example, an optical thin film having a light transmittance of 30% or less at a wavelength of 400 to 500 nm in state 1 and a light transmittance of 60% or more in the state 2 is formed on a transparent substrate. Next, a planar light emitter that emits light having a wavelength of 400 to 500 nm is prepared, and an optical thin film formed on a transparent substrate is placed on the front surface of the light emitter to obtain a display element.

An example of a method for forming an image on the light emitting element is as follows. That is, after determining the position where a specific shape is displayed in the optical thin film surface and irradiating visible light including light having a wavelength of 400 to 500 nm to a portion to be displayed using a known photomask or the like, Emits the illuminant. Here, if the light emission intensity of the light emitter located on the back surface is too high, the transmittance of the portion that has not been irradiated with visible light previously may be increased, and the display shape may be impaired. Usually, it is preferably 1 to 30 mWcm ⁻² , more preferably 1 to 20 mWcm ⁻² , and still more preferably 1 to 15 mWcm ⁻² . As described above, since the entire surface of the display element can be returned to the state 1 by being exposed to ultraviolet light, it can be used repeatedly.

  Moreover, the optical thin film in the present invention can be used as a light shielding material capable of controlling the light shielding performance. For example, when it is used for a transparent plate portion of a showcase, it is possible to freely create an open / closed state without using a black curtain. That is, the optical thin film may be in state 2 when the contents are disclosed, and in state 1 when the contents are not disclosed. As described above, state 1 and state 2 can be switched by irradiation with ultraviolet rays or irradiation with visible light.

  It is also possible to automatically change the transmittance by using the amount of ultraviolet rays as an index. For example, it can be used as a light-transmitting and light-shielding material for building or vehicle window materials or sunglasses. Usually, outside light contains a lot of ultraviolet light in a situation where there is a lot of outside light and a constant light shielding is necessary because it is too bright. When the optical thin film according to the present invention is used, a certain amount of external light can be blocked under a large amount of external light, and a large amount of external light can be taken under a low external light condition.

The optical thin film in the present invention can also be used as a display material using the color. In particular,
When the optical thin film is in the state 1 and irradiated with, for example, blue light (wavelength 450 nm, width 10 nm), the transmittance increases at the wavelength of the irradiated light, and the brown optical thin film changes to blue. When green light (wavelength 550 nm, width 10 nm) or red light (wavelength 650 nm, width 10 nm) is irradiated, the transmittance increases at each wavelength, and the brown film changes to green or red.

  Using this phenomenon, a specific shape can be drawn in multiple colors by irradiating the optical thin film with light of an appropriate wavelength.

  Moreover, it is possible to erase the shape drawn above by irradiating with ultraviolet rays as necessary, and it is possible to repeatedly draw a specific shape by irradiating light of an appropriate wavelength.

  Since the display element obtained by using the optical thin film according to the present invention can be rewritten, it can be expected as a display material for electronic paper which has been rapidly developed recently.

  The composition of the optical thin film in the present invention can be analyzed using a conventionally known means. The atomic composition of the surface is Auger electron spectroscopy (AES), X-ray fluorescence (XRF), X-ray microanalysis (XMA), charged particle excitation X-ray analysis (RBS), X-ray photoelectron spectroscopy (XPS) ), Vacuum ultraviolet photoelectron spectroscopy (UPS), infrared absorption spectroscopy (IR), Raman spectroscopy, secondary ion mass spectrometry (SIMS), low energy ion scattering spectroscopy (ISS), and the like. In addition, the atomic composition and film thickness in the optical thin film should be examined by performing X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS) in the depth direction. Can do. In addition, the configuration of the optical thin film and the state of each layer, in particular, the diameter and existence ratio of particles mainly composed of silver, the closest approach distance and the existence ratio of the particles are the optical microscope measurement of the cross section, the scanning electron microscope measurement (SEM), It can be examined using transmission electron microscopy (TEM).

(Example 1)
One surface of a transparent polyethylene terephthalate film (manufactured by Teijin DuPont, brand name OGX size 50 × 50 mm, thickness 75 μm) is spin-coated with a titanium oxide dispersion (made by Ishihara Sangyo, brand name STS-01), 60 Dry at 30 ° C. for 30 minutes to obtain a titanium oxide film having a thickness of 1 μm. The titanium oxide film corresponds to a base layer. The transmittance and haze value at a wavelength of 550 nm of this titanium oxide film are 70% and 3%, respectively, when the thickness is 200 nm.
Subsequently, particles containing Ag as a main component are formed on the titanium oxide film by using a direct current magnetron sputtering method. The target is pure Ag (purity 99.99%), the sputtering gas is argon, the pressure is 0.5 Pa, the input power is 100 w, and the formation time is 0.25 seconds. Thus, an optical thin film is obtained.
The diameter and the existence ratio of particles mainly composed of silver in the optical thin film obtained above, and the closest distance and the existence ratio of the particles are determined by performing TEM analysis.

Subsequently, ultraviolet rays were irradiated for 10 minutes using a mercury lamp. The wavelength of the irradiated ultraviolet rays was 300 to 400 nm, and the intensity was 1 mWcm ⁻² . The transmittance of light having wavelengths of 450 nm, 550 nm, and 650 nm is measured.
Thereafter, visible light is irradiated for 1 hour using a xenon lamp. In the visible light irradiation, a band-pass filter is used, and only light having a wavelength of 400 to 800 nm is irradiated. The irradiation intensity is 50 mWcm ⁻² . The transmittance of light having wavelengths of 450 nm, 550 nm, and 650 nm is measured, and the amount of change in transmittance before and after irradiation with visible light is obtained.

(Example 2)
This was carried out in the same manner as in Example 1 except that the formation time for forming particles mainly composed of Ag was 0.5 seconds.

(Example 3)
The same operation as in Example 1 was performed except that the formation time for forming particles containing Ag as a main component was 0.75 seconds.

Example 4
It was carried out in the same manner as in Example 1 except that the formation time was set to 1 second when forming the particles mainly composed of Ag.

(Example 5)
The same procedure as in Example 1 was performed except that the formation time was set to 1.25 seconds when forming particles containing Ag as a main component.

(Example 6)
It was carried out in the same manner as in Example 1 except that the formation time was set to 1.5 seconds when forming particles containing Ag as a main component. .

(Example 7)
It was carried out in the same manner as in Example 1 except that the formation time was set to 1.75 seconds when forming particles containing Ag as a main component.

(Example 8)
The same operation as in Example 4 is performed except for the following items.
When producing a base layer composed of a titanium oxide film, a titanium oxide film is formed on one main surface of a transparent polyethylene terephthalate film (manufactured by Teijin DuPont, brand name: OGX size 50 × 50 mm, thickness 75 μm) using a high-frequency sputtering method. A film was formed.
The target is titanium dioxide (purity 99.99%), the sputtering gas is an argon-oxygen mixed gas [partial pressure ratio argon / oxygen = 0.5], the pressure is 0.5 Pa, the input power is 500 w, and the thickness is controlled to be about 200 nm. did.
A shielding plate having a height of 50 mm is installed around the target for the purpose of reducing the number of particles incident on the substrate from an oblique direction during film formation.

  By examining the crystallinity of the base layer using the XRD method (θ-2θ method), it can be confirmed that the X-ray diffraction pattern has a peak at a position of 2θ = 24 to 28 °.

(Comparative Example 1)
The same procedure as in Example 1 is performed except that the formation time is set to 2 seconds when forming particles containing Ag as a main component.

(Comparative Example 2)
When forming particles containing Ag as a main component, the glass substrate on which the titanium oxide layer is formed is immersed in an aqueous silver nitrate solution having a concentration of 1 mol / l for 0.5 minutes, and then the aqueous silver nitrate solution is poured in pure water, and then the temperature is 60. The same procedure as in Example 1 is performed except that drying is performed at 30 ° C. for 30 minutes.

(Comparative Example 3)
The same procedure as in Comparative Example 2 is performed except that the glass substrate on which the titanium oxide layer is formed is immersed in an aqueous silver nitrate solution having a concentration of 1 mol / l for 3 minutes.

(Comparative Example 4)
The same procedure as in Comparative Example 2 is performed except that the glass substrate on which the titanium oxide layer is formed is immersed in an aqueous silver nitrate solution having a concentration of 1 mol / l for 5 minutes.

  The results of Examples 1 to 8 and Comparative Examples 1 to 4 are shown in Table 1. In all the examples, the difference between the transmittance after ultraviolet irradiation and the transmittance after visible light irradiation is 10% or more at any wavelength, which is at a practical level.

Example 9
The same operation as in Example 4 was performed except for the following items.
After forming particles containing Ag as a main component, TiO ₂ was formed thereon using a high-frequency magnetron sputtering method. The target is titanium dioxide (purity 99.99%), the sputtering gas is argon-oxygen mixed gas [partial pressure ratio argon / oxygen = 0.5], the pressure is 0.5 Pa, the input power is 500 w, and the thickness is about 200 nm. Controlled.
A shielding plate having a height of 50 mm is installed around the target for the purpose of reducing the number of particles incident on the substrate from an oblique direction during film formation.

  By examining the crystallinity of the base layer using the XRD method (θ-2θ method), it can be confirmed that the X-ray diffraction pattern has a peak at a position of 2θ = 24 to 28 °. The transmittance and haze value of the base layer produced here at a wavelength of 550 nm are 90% and 0.1%, respectively, when the thickness is 200 nm.

The produced optical thin film was placed under conditions of a temperature of 60 ° C. and a humidity of 90% for 24 hours, and then irradiated with ultraviolet rays for 10 minutes using a mercury lamp. The wavelength of the irradiated ultraviolet light is 300 to 400 nm, and the intensity is 1 mWcm ⁻² . The transmittance of light having a wavelength of 450 nm is measured.
Thereafter, visible light is irradiated for 1 hour using a xenon lamp. In the visible light irradiation, a band-pass filter is used, and only light having a wavelength of 400 to 800 nm is irradiated. The irradiation intensity is 50 mWcm ⁻² . The transmittance of light having a wavelength of 450 nm is measured, and the amount of change in transmittance before and after irradiation with visible light is obtained.
(Comparative Example 5)
An optical thin film was prepared in the same manner as in Comparative Example 3, and after 24 hours in an environment at a temperature of 60 ° C. and a humidity of 90% as in Example 9, the transmittance after irradiation with ultraviolet rays and the transmittance after irradiation with visible light were measured. Then, the amount of change was examined.
(Example 10)
An optical thin film was prepared in the same manner as in Example 4, and after 24 hours in an environment at a temperature of 60 ° C. and a humidity of 90% as in Example 9, the transmittance after ultraviolet irradiation and the transmittance after irradiation with visible light were measured. Then, the amount of change was examined.

  The above results are shown in Table 2. It can be seen that when the titanium oxide layer is formed on particles containing Ag as a main component as in Example 9, high durability is exhibited.

Sectional drawing which shows an example of the optical thin film of this invention Sectional drawing which shows an example of the optical thin film of this invention Sectional drawing which shows an example of the optical thin film of this invention Sectional drawing which shows an example of the optical thin film of this invention Sectional drawing which shows an example of the optical thin film of this invention Sectional drawing which shows an example of the optical thin film of this invention Sectional drawing which shows an example of the optical thin film of this invention Sectional drawing which shows an example of the optical thin film of this invention Sectional drawing which shows an example of the optical thin film of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Base | substrate 20 Base layer 30 Particle 40 which has Ag as a main component Optical thin film 50 which consists of the base layer 20 and the particle 30 which has Ag as a main component 50 Protective layer 60 Intermediate layer

Claims (8)

A thin film containing silver and one or more elements selected from titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, silicon, germanium, phosphorus, and oxygen,
(I) containing particles containing silver as a main component,
(II) The ratio of the number of particles (Ag-2) containing silver having a diameter of 0.5 to 50 nm as a main component to the number of particles (Ag-1) containing silver having a diameter of 0.5 nm to 1 mm as a main component is 50-100%,
(III) The number of silver particles (Ag-3) having a closest distance of 3 to 100 nm between particles mainly composed of silver having a diameter of 0.5 nm to 1 mm is 50 to 100 of the number of silver particles (Ag-1). %
(IV) The particle number density of the particles (Ag-2) is 5 × 10 ^{2 to 2} × 10 ⁵ particles / μm ^2.
An optical thin film characterized by The optical thin film according to claim 1, further comprising a base layer made of a polymer material. Forming at least particles (Ag-1);
2. The step of forming a portion (base layer) composed of an element selected from titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, silicon, germanium, phosphorus, and oxygen. Optical thin film. 4. The optical thin film according to claim 3, wherein the base layer has titanium and oxygen and has a diffraction peak at 2θ = 24 to 28 ° as an X-ray diffraction pattern by the θ-2θ method.   2. The optical thin film according to claim 1, wherein the particles (Ag-1) are particles formed by a vacuum film forming method. 4. The optical thin film according to claim 3, wherein the base layer is formed by a vacuum film forming method. A display device using the optical thin film according to claim 1. A method of creating an image by irradiating the display device according to claim 7 with light rays and controlling the transmittance of the optical thin film.

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