JP2009229946A - Dimming sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dimming sheet which makes a tint close to white in a white turbid mode more than before. <P>SOLUTION: The dimming sheet includes a pair of transparent electrode films having transparent electrodes arranged oppositely to each other and a liquid crystal layer sandwiched between the transparent electrodes, wherein the one where a metal oxide thin film, a metal thin film, and a metal oxide thin film are laminated in this order on a surface of a transparent polymer film on the side of the liquid crystal layer is used as a transparent electrode film disposed on a viewing side. The other one where a composite oxide thin film of indium and tin is laminated on a surface of the transparent polymer film on the side of the liquid crystal layer is used as a transparent electrode film disposed on the side opposite to a viewing side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light control sheet, and more particularly, to a light control sheet using a liquid crystal material.

  Conventionally, a light control sheet in which a liquid crystal layer is sandwiched between a pair of transparent electrode films is known. The light control sheet is usually configured to be able to switch between a transparent mode and a white turbid mode by turning on / off a voltage applied between the transparent electrodes.

  The said light control sheet | seat is arrange | positioned in front surfaces, such as a display apparatus (a liquid crystal display, a plasma display, etc.), for example. And it is used suitably for uses, such as an electronic curtain which switches the display apparatus etc. which are on the back side of a light control sheet to the visible state / invisible state by turning on / off the voltage applied to a light control sheet.

  Until now, a light control sheet in which a liquid crystal layer is sandwiched between two ITO films obtained by forming an ITO sputtered thin film on a resin film such as polyethylene terephthalate has been widely used as the light control sheet. (Patent Document 1).

JP-A-2-205822

  However, the conventional light control sheet has the following problems.

  That is, when the light control sheet is in the cloudiness mode, the viewer of the light control sheet mainly sees the reflected light reflected by the light control sheet. Generally, the color of the light control sheet is favored by viewers as it is closer to white (white to blue).

  However, the conventional light control sheet (using a pair of ITO films) is dark on the other side of the light control sheet (the side opposite to the viewing side), for example, when the power of the display device is turned off. If it is black, it will look yellowish to the viewer if it is in cloudy mode. Therefore, it has been required to improve the color of the light control sheet in a design manner.

  This invention is made | formed in view of the said situation, and the subject which this invention tends to solve is providing the light control sheet which can make the color in the cloudy mode close to white compared with the past.

  In order to solve the above problems, a light control sheet according to the present invention has a pair of transparent electrode films disposed so that the transparent electrodes face each other, and a liquid crystal layer sandwiched between the transparent electrodes. The transparent electrode film placed on the viewing side has a metal oxide thin film, a metal thin film, and a metal oxide thin film laminated in this order on the surface of the transparent polymer film on the liquid crystal layer side. The gist of the transparent electrode film disposed on the side opposite to the side is that a composite oxide thin film of indium and tin is laminated on the surface of the transparent polymer film on the liquid crystal layer side.

  Here, the metal oxide thin film is preferably a titanium oxide thin film.

  The metal thin film is preferably a silver thin film or a silver alloy thin film.

  The metal oxide thin film preferably contains an organic component.

  Moreover, it is preferable that a barrier thin film mainly composed of a metal oxide is further formed on at least one surface of the metal thin film.

  Moreover, it is preferable that the metal oxide which comprises the said barrier thin film is a titanium oxide.

  Moreover, it is preferable that the transparent electrode film arrange | positioned on the opposite side to the said visual recognition side has laminated | stacked the reflective thin film on the surface on the opposite side to the surface at the side of the liquid crystal layer of a transparent polymer film.

  Moreover, the said light control sheet | seat is good to be arrange | positioned in the front surface of a display apparatus. At this time, the display device is preferably installed in a wall.

  Moreover, it is preferable that the film thickness of the said metal oxide thin film exists in the range of 5-60 nm.

  In the light control sheet according to the present invention, the transparent electrode film disposed on the viewing side has a metal oxide thin film, a metal thin film, and a metal oxide thin film in this order on the liquid crystal layer side surface of the transparent polymer film. It is configured by stacking. Moreover, the transparent electrode film arrange | positioned on the opposite side (non-viewing side) from the visual recognition side is comprised by laminating | stacking the complex oxide thin film of indium and tin on the surface at the liquid crystal layer side of a transparent polymer film. .

  The transparent electrode film on the viewing side having the above-described configuration has less transmission of the red component and the yellow component as compared with the ITO film. Therefore, it is possible to reduce the red and yellow components of the scattered reflected light that is incident from the viewer side, scattered and reflected by the liquid crystal layer, and returns to the viewer side.

  Moreover, the transparent electrode film on the non-viewing side having the above-described configuration has a relatively high reflectance, and the reflected light contains a lot of blue components. Therefore, it is possible to increase the blue component of the scattered reflected light that enters from the viewer side, reflects off the transparent electrode film on the non-viewing side, and returns to the viewer side.

  Therefore, according to the light control sheet which concerns on this invention, compared with the past, it becomes possible to make the color eyes at the time of a cloudiness mode close to white.

  Here, when the metal oxide thin film is a titanium oxide thin film, the visible light transmittance is likely to be relatively high. Therefore, it becomes easy to increase the amount of scattered reflected light returning to the viewer side, and it is easy to contribute to whitening of the color in the cloudiness mode.

  Moreover, when the said metal thin film is a silver thin film or a silver alloy thin film, it is excellent in visible light transmittance | permeability and electroconductivity. Moreover, it becomes easy to increase the amount of scattered reflected light returning to the viewer side, and to contribute to whitening of the color in the cloudy mode. Furthermore, the in-plane voltage uniformity when the voltage is on is high, and color unevenness is less likely to occur.

  Moreover, when the said metal oxide thin film contains organic content, the softness | flexibility of a light control sheet can be improved.

  In addition, when a barrier thin film mainly composed of a metal oxide is formed on at least one surface of the metal thin film, the diffusion of metal elements constituting the metal thin film into the metal oxide thin film is suppressed. can do.

  Therefore, even when exposed to a thermal environment, it is easy to maintain the color of the white color in the cloudy mode and contribute to improving the durability of the light control sheet.

  At this time, when the metal oxide constituting the barrier thin film is titanium oxide, diffusion of constituent elements of the metal thin film such as silver is easily suppressed.

  Moreover, when the reflective thin film is laminated | stacked on the surface on the opposite side to the liquid crystal layer side surface of the transparent polymer film among the surfaces of the transparent electrode film on the non-viewing side, The reflectance can be improved. Therefore, it becomes easy to contribute to whitening of the color in the cloudiness mode.

  Moreover, when the said light control sheet is arrange | positioned and used for the front surface of a display apparatus, it is excellent in the designability as a blindfold of a display apparatus.

  At this time, when the display device is installed in the wall, the color of the light control sheet in the cloudiness mode is close to white, so that the display device is turned off when the display device is turned off. The presence can be made less noticeable.

  Moreover, when the film thickness of the metal oxide thin film is in the range of 5 to 60 nm, the balance between the amount of decrease in the red component / yellow component of the transmitted light and the visible light transmittance is excellent.

  The light control sheet according to the present embodiment (hereinafter referred to as “the present sheet”) will be described in detail.

1. This sheet | seat This sheet | seat has a pair of transparent electrode film and a liquid-crystal layer. Both transparent electrode films have a transparent electrode on one side of the transparent polymer film. The liquid crystal layer is sandwiched between the transparent electrodes of a pair of transparent electrode films arranged so that the transparent electrodes are opposed to each other.

1.1 Transparent electrode film One side is arrange | positioned among the both transparent electrode films at the visual recognition side with a viewer. The other is arranged on the side opposite to the viewer (non-viewing side). For example, a display device such as a liquid crystal display, a plasma display, or an organic EL display can be placed on the non-viewing side.

  The transparent polymer film constituting both transparent electrode films is a base for forming a transparent electrode. Any material can be used as long as it has transparency in the visible light region and can form a thin film on its surface without any hindrance.

 Specific examples of the material for the transparent polymer film include polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polystyrene, polyimide, polyamide, polybutylene terephthalate, polyethylene naphthalate. Examples thereof include polymer materials such as phthalate, polysulfone, polyethersulfone, polyetheretherketone, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, triacetyl cellulose, polyurethane, and cycloolefin polymer. These may be contained alone or in combination of two or more. Two or more kinds can be laminated and used. In addition, the transparent polymer which comprises both the transparent electrode films may consist of the same material, and may consist of a different material.

  Among these materials, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, cycloolefin polymer and the like can be exemplified as suitable materials from the viewpoint of excellent transparency, durability, workability and the like.

  The transparent polymer film may have an easy adhesion layer or the like formed on one side or both sides.

  The thickness of the transparent polymer film can be variously adjusted in consideration of the application, optical characteristics, durability, and the like of the sheet. The lower limit value of the thickness of the transparent polymer film is preferably 10 μm or more, more preferably 25 μm or more, from the viewpoint of ease of handling and strength. On the other hand, the upper limit value of the thickness of the transparent polymer film is preferably 500 μm or less, more preferably 250 μm or less, from the viewpoints of transparency and economy.

  Here, the transparent electrode film on the viewing side and the transparent electrode film on the non-viewing side have different configurations of the transparent electrodes that each has. This will be described in detail below.

1.1.1 Transparent electrode provided on viewing-side transparent electrode film <Laminated structure>
The transparent electrode film on the viewing side has a metal oxide thin film (hereinafter sometimes abbreviated as “MO”) and a metal thin film (hereinafter abbreviated as “M”) on the surface of the transparent polymer film on the liquid crystal layer side. And a transparent electrode having a three-layer structure in which a metal oxide thin film (MO) is laminated in this order.

  A barrier thin film (hereinafter sometimes abbreviated as “B”) may be further formed on one side or both sides of the metal thin film (M). In addition, when forming a barrier thin film, since a barrier thin film is a thin film attached to each metal thin film, in this application, the number of lamination | stacking is counted by making the metal thin film including a barrier thin film into one layer.

  Therefore, as a laminated structure that can be taken by the transparent electrode on the viewing side, specifically, for example, MO│B / M / B│MO, MO│B / M│MO, MO│M from the transparent polymer film side. / B | MO, MO | M | MO, etc. can be exemplified. Note that “|” means a layer separation.

  Among these, as a suitable laminated structure of the transparent electrode on the viewing side, the metal element constituting the metal thin film (M) diffuses into the metal oxide thin film (MO) when exposed to a thermal environment. From the standpoint that it is easy to suppress the durability and the durability can be improved, it is preferable that the barrier thin film (B) is formed on at least one surface of the metal thin film (M). More preferably, the metal thin film (M) having the barrier thin film (B) formed on both sides thereof is preferable.

  The transparent electrode on the viewing side is a five-layer structure in which a metal thin film and a metal oxide thin film are further laminated in this order on the third metal oxide thin film, or on the third metal oxide thin film. Further, a seven-layer structure in which a metal thin film, a metal oxide thin film, a metal thin film, and a metal oxide thin film are further laminated in this order may be used. Also in these cases, a barrier thin film may be formed on one side or both sides of the metal thin film. Preferably, the transparent electrode on the viewing side may have the above-described various three-layer structures because of excellent balance between color, visibility, and manufacturing cost.

  In the transparent electrode on the viewing side, each thin film may be formed at a time or may be formed in a divided manner. In addition, some or all of the thin films included in the laminated structure may be divided and formed. When each thin film is composed of a plurality of divided layers, the number of divisions may be the same or different for each thin film. In addition, a division | segmentation layer is not counted as a lamination | stacking number, and one thin film formed by the assembly of a plurality of division layers is counted as one layer.

  The composition or material of each thin film may be formed from the same composition or material, or may be formed from different compositions or materials. This also applies to the case where each thin film is composed of a plurality of divided layers.

  The film thickness of each thin film can be varied in consideration of color, transparency, conductivity and the like.

  The transparent electrode film on the viewing side generally has the transparent electrode having the laminated structure described above. Hereinafter, each configuration of the transparent electrode will be described in more detail.

<Metal oxide thin film (MO)>
In the transparent electrode on the viewing side, the metal oxide thin film has transparency in the visible light region and can function mainly as a high refractive index thin film. Here, the high refractive index means a case where the refractive index for light of 633 nm is 1.7 or more.

Specific examples of the metal oxide include titanium oxide (TiO ₂ , titanate, etc.), zinc oxide (ZnO, etc.), indium oxide, tin oxide (SnO _2, etc.). ), An oxide of indium and tin (such as ITO), an oxide of magnesium, an oxide of aluminum, an oxide of zirconium, an oxide of niobium, an oxide of cerium, and the like. These may be contained alone or in combination of two or more. Further, these metal oxides may be double oxides in which two or more metal oxides are combined.

The metal oxide is preferably a titanium oxide such as titanium (IV) oxide (TiO ₂ ) or titanate. This is because, since the visible light transmittance is relatively easy to increase, it is easy to increase the amount of scattered reflected light returning to the viewer side, and it is easy to contribute to whitening of the color in the cloudy mode.

  Here, although the metal oxide thin film is mainly comprised from the metal oxide mentioned above, you may contain organic content other than a metal oxide. It is because the softness | flexibility of this sheet | seat can be improved more by containing an organic content. Specific examples of this type of organic component include components derived from a material for forming a metal oxide thin film, such as a component derived from a starting material of a sol-gel method.

  More specifically, examples of the organic component include organic metal compounds (including decomposition products thereof) such as metal alkoxides, metal acylates, and metal chelates of the above-described metal oxides, and the above organic metals. Examples thereof include various additives such as an organic compound (described later) that reacts with a compound to form an ultraviolet-absorbing chelate. These may be contained alone or in combination of two or more.

  The lower limit of the content of the organic component contained in the metal oxide thin film is preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably, from the viewpoint of easily imparting flexibility. It is good that it is 10% by mass or more. On the other hand, the upper limit of the content of the organic component contained in the metal oxide thin film is preferably 30% by mass or less, from the viewpoint of easily ensuring a high refractive index and easily ensuring solvent resistance. More preferably, it is 25 mass% or less, More preferably, it is good in it being 20 mass% or less.

  In addition, content of the said organic content can be investigated using a X ray photoelectron spectroscopy (XPS) etc. Moreover, the kind of said organic content can be investigated using infrared spectroscopy (IR) (infrared absorption analysis) etc.

  The film thickness of the metal oxide thin film can be adjusted in consideration of the color and the visible light transparency.

  The lower limit of the thickness of the metal oxide thin film is preferably 5 nm or more, more preferably 7 nm or more, and further preferably 10 nm or more from the viewpoint of visible light transparency and the like. On the other hand, the upper limit value of the thickness of the metal oxide thin film is preferably 60 nm or less, more preferably 50 nm or less, and further preferably 40 nm or less, from the viewpoint of the color of transmitted light, visible light transparency, and the like. good.

  The metal oxide thin film having the above structure can be formed by either a vapor phase method or a liquid phase method. The liquid phase method does not need to be evacuated or use a large electric power as compared with the gas phase method. Therefore, it is advantageous in terms of cost, and is excellent in productivity.

  As the liquid phase method, a sol-gel method can be suitably used from the viewpoint of easily leaving an organic component.

  More specifically, as the sol-gel method, for example, a coating liquid containing a metal organometallic compound that constitutes a metal oxide is coated in a thin film shape, and this is dried as necessary to obtain a metal oxide. Examples of the method include forming a precursor film of a thin film and then hydrolyzing and condensing an organometallic compound in the precursor film to synthesize an oxide of a metal constituting the organometallic compound. . According to this, a metal oxide thin film containing a metal oxide as a main component and containing an organic component can be formed. Hereinafter, the above method will be described in detail.

  The coating liquid can be prepared by dissolving the organometallic compound in a suitable solvent. In this case, specific examples of the organometallic compound include organic compounds of metals such as titanium, zinc, indium, tin, magnesium, aluminum, zirconium, niobium, cerium, silicon, hafnium, and lead. Can do. These may be contained alone or in combination of two or more.

  Specific examples of the organometallic compound include metal alkoxides, metal acylates, and metal chelates of the above metals. A metal chelate is preferable from the viewpoint of stability in air.

  As the organic metal compound, in particular, a metal organic compound that can be a metal oxide having a high refractive index can be preferably used. Examples of such organometallic compounds include organic titanium compounds.

  Specific examples of the organic titanium compound include M-O-R bonds such as tetra-n-butoxy titanium, tetraethoxy titanium, tetra-i-propoxy titanium, and tetramethoxy titanium (R represents an alkyl group). , M represents a titanium atom) and an acylate of titanium having an M—O—CO—R bond (R represents an alkyl group and M represents a titanium atom) such as isopropoxy titanium stearate. Examples thereof include titanium chelates such as diisopropoxy titanium bisacetylacetonate, dihydroxy bis lactato titanium, diisopropoxy bis triethanolaminato titanium, diisopropoxy bis ethyl acetoacetate titanium, and the like. These may be used alone or in combination. These may be either monomers or multimers.

  The content of the organometallic compound in the coating liquid is preferably from 1 to 20% by mass, more preferably from 3 to 20% from the viewpoint of the film thickness uniformity of the coating film and the film thickness that can be applied at one time. It is good if it exists in the range of 15 mass%, More preferably, 5-10 mass%.

  Specific examples of the solvent for dissolving the organometallic compound include alcohols such as methanol, ethanol, propanol, butanol, heptanol and isopropyl alcohol, organic acid esters such as ethyl acetate, acetonitrile, acetone and methyl ethyl ketone. Examples thereof include ketones such as tetrahydrofuran, cycloethers such as dioxane, acid amides such as formamide and N, N-dimethylformamide, hydrocarbons such as hexane, aromatics such as toluene, and the like. These may be used alone or in combination.

  At this time, the amount of the solvent is preferably 5 to 100 times the amount of the solid content weight of the organometallic compound from the viewpoint of the film thickness uniformity of the coating film and the film thickness that can be applied at one time. More preferably, the amount is 7 to 30 times, and further preferably 10 to 20 times.

  When the amount of the solvent is more than 100 times, the film thickness that can be formed by a single coating becomes thin, and a tendency to require many coatings to obtain a desired film thickness is observed. On the other hand, when the amount is less than 5 times, the film thickness becomes too thick, and there is a tendency that the hydrolysis / condensation reaction of the organometallic compound does not proceed sufficiently. Therefore, the amount of the solvent is preferably selected in consideration of these.

  In addition, the coating liquid may contain water as necessary from the viewpoint of promoting hydrolysis by a sol-gel method and facilitating a high refractive index.

  The coating solution is prepared, for example, by using a stirring means such as a stirrer to mix an organometallic compound weighed to a predetermined ratio, an appropriate amount of solvent, and other components added as necessary. It can be prepared by a method such as stirring and mixing for a period of time. In this case, the components may be mixed at a time or may be mixed in a plurality of times.

  In addition, as a coating method of the coating liquid, from the viewpoint of easy uniform coating, a micro gravure method, a gravure method, a reverse roll coating method, a die coating method, a knife coating method, a dip coating method, a spin coating method, a bar coating method, and the like. Various wet coating methods such as a coating method can be exemplified as suitable ones. These may be appropriately selected and used, and one or more may be used in combination.

  Further, when the coated coating liquid is dried, it may be dried using a known drying apparatus. In this case, as the drying conditions, specifically, for example, a temperature range of 80 ° C to 120 ° C, Examples of the drying time include 0.5 minutes to 5 minutes.

  Specific examples of means for hydrolysis / condensation reaction of the organometallic compound in the precursor film include various means such as ultraviolet irradiation, electron beam irradiation, and heating. These may be used alone or in combination of two or more. Among these, ultraviolet irradiation can be preferably used. This is because, compared with other means, a metal oxide can be generated at a low temperature in a short time, and it is difficult to apply a load due to heat such as thermal deterioration to the transparent polymer film. In addition, there is an advantage that an organic metal compound (including a decomposition product thereof) or the like is easily left as an organic component.

  In this case, specific examples of the ultraviolet irradiator to be used include a mercury lamp, a xenon lamp, a deuterium lamp, an excimer lamp, a metal halide lamp, and the like. These may be used alone or in combination of two or more.

  Further, the amount of ultraviolet light to be irradiated can be variously adjusted in consideration of the kind of the organometallic compound mainly forming the precursor film, the thickness of the coating layer, and the like. However, if the amount of ultraviolet light to be irradiated is too small, it is difficult to increase the refractive index of the metal oxide thin film. On the other hand, if the amount of ultraviolet light to be irradiated is excessively large, the transparent polymer film may be deformed by heat generated during the ultraviolet irradiation. Therefore, these should be noted.

The amount of ultraviolet light to be irradiated is preferably 300 to 8000 mJ / cm ² , more preferably 500, when the measurement wavelength is 300 to 390 nm, from the viewpoint of the refractive index of the metal oxide thin film, the damage received by the transparent polymer film, and the like. It is good to be within the range of ˜5000 mJ / cm ² .

  As a means for hydrolyzing and condensing the organometallic compound in the precursor film, when using ultraviolet irradiation, an organic compound that reacts with the organometallic compound to form an ultraviolet-absorbing chelate in the coating liquid described above. It is good to add additives such as. When the above additives are added to the coating solution that is the starting solution, UV irradiation is performed where the UV-absorbing chelate has been formed in advance, so that the high refraction of the metal oxide thin film is relatively low. This is because it becomes easy to achieve the rate.

  Specific examples of the additive include additives such as β diketones, alkoxy alcohols, and alkanolamines. More specifically, examples of the β diketones include acetylacetone, benzoylacetone, ethyl acetoacetate, methyl acetoacetate, diethyl malonate, and the like. Examples of the alkoxy alcohols include 2-methoxyethanol, 2-ethoxyethanol, 2-methoxy-2-propanol, and the like. Examples of the alkanolamines include monoethanolamine, diethanolamine, and triethanolamine. These may be used alone or in combination.

  Of these, β diketones are particularly preferred, and acetylacetone can be most preferably used.

  The blending ratio of the additive is preferably 0.1 to 1 mol of the metal atom in the organometallic compound from the viewpoint of easiness in increasing the refractive index and stability in the state of the coating film. It is good that it is in the range of 2 times mole, more preferably 0.5 to 1.5 times mole.

<Metal thin film (M)>
In the transparent electrode on the viewing side, the metal thin film can mainly function as a conductive layer.

  Specific examples of the metal include silver, gold, platinum, copper, aluminum, chromium, titanium, zinc, tin, nickel, cobalt, niobium, tantalum, tungsten, zirconium, lead, palladium, and indium. And alloys of these metals can be exemplified. These may be contained alone or in combination of two or more.

  As the metal, silver or a silver alloy is preferable from the viewpoints of conductivity, visible light transmittance at the time of lamination, and low transmittance of yellow to red light. More preferably, silver containing silver as a main component and containing at least one metal element such as bismuth, gold, palladium, platinum, or copper from the viewpoint of improving durability against an environment such as heat, light, and water vapor. It should be an alloy. More preferably, it is a silver alloy (Ag—Bi alloy) containing bismuth from the viewpoint that the effect of suppressing the diffusion of silver is large and advantageous in terms of cost.

  In the case of using a silver alloy containing bismuth, in addition to silver and bismuth, for example, other elements and inevitable impurities may be contained as long as they do not adversely affect the aggregation / diffusion suppression effect of silver.

  Specific examples of the other elements include elements that can be dissolved in Ag such as Mg, Pd, Pt, Au, Zn, Al, Ga, In, Sn, Sb, Li, Cd, Hg, and As. ; Be, Ru, Rh, Os, Ir, Cu, Ge, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Si, Tl, Pb, etc., in Ag-Bi alloys Element which can be precipitated as a single phase in Y; La, Ce, Nd, Sm, Gd, Tb, Dy, Ti, Zr, Hf, Na, Ca, Sr, Ba, Sc, Pr, Eu, Ho, Er, Tm Examples include elements capable of precipitating intermetallic compounds with Ag such as Yb, Lu, S, Se, and Te. These may be contained alone or in combination of two or more.

  When using a silver alloy containing bismuth, the lower limit of the bismuth content is preferably 0.01 atomic% or more, more preferably 0.05 atomic% or more, and still more preferably, from the viewpoint of obtaining the effect of addition. It may be 0.1 atomic% or more.

  On the other hand, the upper limit of the bismuth content is preferably 5 atomic% or less, more preferably 2 atomic% or less, and still more preferably 1 atomic% from the viewpoint of manufacturability such as easy production of a sputtering target. It is good to be below.

  The bismuth ratio can be measured using ICP analysis.

  The lower limit of the thickness of the metal thin film is preferably 3 nm or more, more preferably 4 nm or more, and still more preferably 5 nm or more, from the viewpoints of stability and conductivity. On the other hand, the upper limit value of the thickness of the metal thin film is preferably 30 nm or less, more preferably 20 nm or less, and further preferably 15 nm or less, from the viewpoint of transparency of visible light, economy, and the like.

  Here, as a method of forming the metal thin film, specifically, for example, physical vapor deposition (PVD) such as vacuum deposition, sputtering, ion plating, MBE, laser ablation, thermal CVD, etc. Examples thereof include a vapor phase method such as a chemical vapor deposition method (CVD) such as a plasma CVD method. The metal thin film may be formed using any one of these methods, or may be formed using two or more methods.

  Of these methods, sputtering methods such as a DC magnetron sputtering method and an RF magnetron sputtering method can be preferably used from the viewpoint of obtaining a dense film quality and relatively easy film thickness control.

<Barrier thin film (B)>
In the transparent electrode on the viewing side, the barrier thin film mainly has a barrier function that suppresses diffusion of elements constituting the metal thin film into the metal oxide thin film. Moreover, by interposing between a metal oxide thin film and a metal thin film, it can also contribute to the improvement of adhesiveness of both.

  The barrier thin film is preferably a continuous film, but may have a discontinuous portion such as a floating island as long as the above diffusion can be suppressed.

  Specific examples of the metal oxide constituting the barrier thin film include, for example, titanium oxide, zinc oxide, indium oxide, tin oxide, indium and tin oxide, and magnesium oxide. And aluminum oxide, zirconium oxide, niobium oxide, cerium oxide, and the like. These may be contained alone or in combination of two or more. Further, these metal oxides may be double oxides in which two or more metal oxides are combined. The barrier thin film may contain inevitable impurities in addition to the metal oxide.

  Here, as a barrier thin film, it is good to be mainly comprised from the metal oxide which comprises a metal oxide thin film from a viewpoint of being excellent in the diffusion inhibitory effect of the metal which comprises a metal thin film, and being excellent in adhesiveness. .

More specifically, for example, when a TiO ₂ thin film is selected as the metal oxide thin film, the barrier thin film is a titanium oxide thin film mainly composed of an oxide of Ti which is a metal constituting the TiO ₂ thin film. And good.

  The barrier thin film (B) is mainly composed of a metal oxide in the same manner as the metal oxide thin film (MO), but is set to be thinner than the metal oxide thin film (MO). This is because the diffusion of the metal constituting the metal thin film (M) occurs at the atomic level, so that it is less necessary to increase the film thickness to a sufficient level to ensure the refractive index. Moreover, by forming it thinly, the film formation cost is reduced correspondingly, which can contribute to the reduction of the manufacturing cost of the sheet.

  The lower limit value of the thickness of the barrier thin film is preferably 1 nm or more, more preferably 1.5 nm or more, and further preferably 2 nm or more, from the viewpoint of easily ensuring barrier properties. On the other hand, the upper limit value of the thickness of the barrier thin film is preferably 15 nm or less, more preferably 10 nm or less, and still more preferably 8 nm or less, from the viewpoint of economy and the like.

  When the barrier thin film is mainly composed of titanium oxide, the lower limit value of the atomic molar ratio Ti / O of titanium to oxygen in the titanium oxide is 1.0 / 4.0 or more from the viewpoint of barrier properties and the like. Preferably, 1.0 / 3.8 or higher, more preferably 1.0 / 3.5 or higher, even more preferably 1.0 / 3.0 or higher, most preferably 1.0 / 2.8. It is good to be above.

  When the barrier thin film is mainly composed of titanium oxide, the upper limit value of the atomic molar ratio Ti / O of titanium to oxygen in the titanium oxide is preferably 1.0 / 0.5 or less, more preferably 1.0 / 0.7 or less, more preferably 1.0 / 1.0 or less, even more preferably 1.0 / 1.2 or less, most preferably 1 0.0 / 1.5 or less is preferable.

  The Ti / O ratio can be calculated from the composition of the film. As a method for analyzing the composition of the film, energy dispersive X-ray fluorescence analysis (EDX) can be preferably used from the viewpoint that the composition of an extremely thin thin film can be analyzed relatively accurately.

  A specific composition analysis method will be described. First, using an ultrathin section method (microtome) or the like, a test piece having a thickness of 100 nm or less in the cross-sectional direction of the laminated structure including the film to be analyzed is prepared. Next, the laminated structure and the position of the film are confirmed from the cross-sectional direction with a transmission electron microscope (TEM). Next, an electron beam is emitted from the electron gun of the EDX apparatus and is incident on the vicinity of the central portion of the film to be analyzed. Electrons incident from the surface of the test specimen enter to a certain depth and generate various electron beams and X-rays. By detecting and analyzing characteristic X-rays at this time, the constituent elements of the film can be analyzed.

  The barrier thin film is preferably formed by a vapor phase method from the viewpoint that a dense film can be formed and a thin film with a thickness of several nanometers to several tens of nanometers can be formed with a uniform film thickness.

  Specific examples of the vapor phase method include physical vapor deposition methods (PVD) such as vacuum deposition, sputtering, ion plating, MBE, and laser ablation, thermal CVD, and plasma CVD. Examples thereof include chemical vapor deposition (CVD) and the like.

  At this time, since the barrier thin film is mainly formed of a metal oxide, it is necessary to introduce a gas containing oxygen into the atmosphere at the time of film formation by the respective thin film forming methods.

  Each barrier thin film that can be included in the laminated structure may be formed by using any one of these vapor phase methods, or by using two or more methods. May be.

  As the vapor phase method, a sputtering method such as a DC magnetron sputtering method or an RF magnetron sputtering method is preferable from the viewpoint of excellent adhesion at the film interface as compared with a vacuum deposition method and the like and easy control of the film thickness. Can be used.

  However, when forming a barrier thin film, for example, a gas containing oxygen as a reactive gas is mixed with an inert gas such as argon or neon as a sputtering gas, and the thin film is reacted with metal and oxygen. (Reactive sputtering method).

  In addition, for example, when a titanium oxide thin film having the Ti / O ratio is obtained by using the reactive sputtering method, the oxygen concentration in the atmosphere (volume ratio of the gas containing oxygen to the inert gas) An optimum ratio may be selected as appropriate in consideration of the thickness range.

<Lamination method of each thin film>
In forming the transparent electrode on the viewing side, the formation method of the metal oxide thin film (MO), the formation method of the metal thin film (M), and the formation method of the barrier thin film (B) are combined as appropriate. As a method of laminating the metal oxide thin film (MO), the metal thin film (M), and the barrier thin film (B) on the surface of the molecular film, specifically, for example, the following method is exemplified. Can do. Hereinafter, the case where a transparent electrode having a laminated structure of MO | B / M / B | MO is formed on the surface of the transparent polymer film will be described.

  First, a metal oxide thin film (MO) is formed on the surface of a transparent polymer film by a liquid phase method such as the sol-gel method described above, and then wound on a roll.

  Next, this roll is mounted in a film forming chamber of a thin film forming apparatus using a vapor phase method such as the above-described reactive sputtering method, and the metal oxide thin film (MO) is formed in an oxygen-containing atmosphere while the roll is fed out. A barrier thin film (B) is formed on the surface. Next, the film body is moved to another film formation chamber, and subsequently, a metal thin film (M) is formed on the surface of the barrier thin film (B) in an atmosphere substantially free of oxygen. Next, the film body is moved to another film forming chamber, and in the same manner as described above, a barrier thin film (B) is formed on the surface of the metal thin film (M) in an atmosphere containing oxygen, and this is wound on a roll. take.

  Next, while feeding out this roll, a metal oxide thin film (MO) is formed on the surface of the barrier thin film (B) in the same manner as described above, and this is wound around the roll.

  Basically, if such an operation is performed, the transparent electrode film on the viewing side can be continuously produced. When each thin film is formed of a plurality of divided layers, each operation may be repeated for the number of divisions.

In the transparent electrode on the viewing side, the materials for the metal oxide thin film (MO), the metal thin film (M), and the barrier thin film (B) can be appropriately selected from those described above as necessary. . As a suitable combination of film materials, the metal oxide thin film (MO) is a titanium oxide thin film, preferably a TiO ₂ thin film, and the metal thin film (M) is a silver or silver alloy thin film, preferably a silver alloy thin film, a barrier. The thin film (B) can be exemplified by a combination of titanium oxide thin films. This is because the balance of color tone, dimming property, and visible light transparency in the cloudy mode is good.

1.1.2 Transparent electrode provided on transparent electrode film on non-viewing side The transparent electrode film on the non-viewing side is a composite oxide thin film (ITO thin film) of indium and tin on the surface of the transparent polymer film on the liquid crystal layer side. The transparent electrode which consists of.

  The transparent electrode on the non-viewing side may be composed of one layer of ITO thin film, or may be composed of two or more layers of ITO thin film. Preferably, from the viewpoint of economy and the like, it may be composed of a single layer of ITO thin film.

  The lower limit of the thickness of the ITO thin film is preferably 5 nm or more, more preferably 10 nm or more, and further preferably 20 nm or more, from the viewpoints of conductivity and stability. On the other hand, the upper limit value of the thickness of the ITO thin film is preferably 200 nm or less, more preferably 100 nm or less, and still more preferably 50 nm or less, from the viewpoint of difficulty in cracking, economy, and the like.

  The ITO thin film is preferably formed by a vapor phase method from the viewpoint that a dense film can be formed and a thin film with a thickness of several nanometers to several tens of nanometers can be formed with a uniform film thickness.

  Specific examples of the vapor phase method include physical vapor deposition methods (PVD) such as vacuum deposition, sputtering, ion plating, MBE, and laser ablation, thermal CVD, and plasma CVD. Examples thereof include chemical vapor deposition (CVD) and the like.

  As the vapor phase method, a sputtering method such as a DC magnetron sputtering method or an RF magnetron sputtering method is preferable from the viewpoint of excellent adhesion at the film interface as compared with a vacuum deposition method and the like and easy control of the film thickness. Can be used.

1.2 Liquid Crystal Layer In this sheet, the liquid crystal layer is sandwiched between the transparent electrodes of the pair of transparent electrode films described above.

  Here, as long as the liquid crystal layer contains liquid crystal molecules and can be dimmed, the entire layer may be filled with liquid crystal molecules or a mixture of liquid crystal molecules and polymers. good. Specific examples of the latter case include, for example, a liquid crystal molecule dispersed in a polymer.

  The liquid crystal molecules used are not particularly limited. Specifically, for example, any liquid crystal molecule such as nematic type, cholesteric type, and smectic type is applicable. Preferably, it contains nematic liquid crystal molecules. You may use these 1 type or in mixture of 2 or more types.

  Specific examples of nematic liquid crystal molecules include poly (p-phenylene terephthalamide), poly (p-benzamide), poly (p-phenylene benzobisoxazole), poly (p-phenylene benzobisthiazole), and the like. Examples thereof include 4'-methoxybenzylidene-4'butylaniline, 4-cyano-4'-hexoxybiphenyl, a cyanobiphenyl compound, a cyanophenylcyclohexane compound, and a cyanocyclohexylcyclohexane compound.

  Specific examples of cholesteric liquid crystal molecules include cholesteryl linoleate, cholesteryl oleate, cellulose, cellulose derivatives, and polypeptides.

  Specific examples of smectic liquid crystal molecules include polyester.

  As the polymer, any polymer can be used as long as it has transparency and does not adversely affect the alignment of liquid crystal molecules. Specific examples include vinyl ether acrylate and copolymers of vinyl ether acrylate and other monomers. These may be used alone or in combination.

  Among these, a vinyl ether acrylate copolymer is preferable from the viewpoints of excellent transparency and a good relationship with the refractive index with liquid crystal molecules.

  Moreover, when mixing a liquid crystal molecule and polymer | macromolecule, the ratio of both is not specifically limited, An optimal ratio can be selected in consideration of light control property, cost, etc. Specifically, for example, the preferred range is 50 to 90% by weight as the proportion of the liquid crystal molecules and 10 to 50% by weight as the proportion of the polymer.

  In the liquid crystal layer, one or more additives such as a photoinitiator such as an ultraviolet initiator and an antioxidant may be contained as necessary.

  The thickness of the liquid crystal layer can be variously adjusted in consideration of the color in the cloudy mode, the driving voltage, the economy, and the like. Basically, as the thickness is increased, the amount of scattered light reflected and returned to the viewer side increases, and the effect of improving the color tends to increase.

  The lower limit of the thickness of the liquid crystal layer is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 7 μm or more, from the viewpoint of increasing the amount of scattered reflected light that returns to the viewer side. Good to be. On the other hand, the upper limit of the thickness of the liquid crystal layer is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less, from the viewpoints of driving voltage and economy.

  The liquid crystal layer may be sealed by, for example, providing a sealing material on the outer periphery of the light control region from the viewpoint of blocking moisture and the like and preventing leakage of the liquid crystal material. In addition, a region without a transparent electrode may be formed on the outer periphery of the light control region, and the two transparent polymer films may be heat-sealed and sealed.

  In this case, specific examples of the sealing material include photo-curing resins such as thermosetting resins and ultraviolet-curing resins, and mixtures thereof.

  As a method for forming the liquid crystal layer, specifically, for example, a method in which the transparent electrode surfaces of a pair of transparent electrode films are opposed to each other, a predetermined gap is formed, and a liquid crystal material is naturally or vacuum injected into the gap. Examples include a method in which a liquid crystal material is dropped or applied on the transparent electrode surface of the transparent electrode film, and then the transparent electrode surface of the other transparent electrode film is bonded. In addition, in order to form the said clearance gap uniformly, you may spray a spacer etc.

  When a liquid crystal layer containing a polymer is formed, a mixture of liquid crystal molecules and a polymer may be used from the beginning, and this may be injected into the gap. A monomer capable of generating the polymer may be used as the gap. After injection into the polymer, the monomer may be polymerized using heat or light to form a polymer.

  The latter can be preferably used from the viewpoint of low molecular weight, high fluidity, and ease of injection.

1.3 Reflective thin film In this sheet, a reflective thin film may be laminated on the surface of the transparent electrode film on the non-viewing side opposite to the liquid crystal layer side. In this case, the reflectance of the transparent electrode film on the non-viewing side can be improved. Therefore, there is an advantage that it is easy to contribute to whitening of the color in the cloudy mode.

Specifically, as the reflective thin film, for example, a laminated film in which a high refractive index thin film such as a TiO ₂ thin film and a low refractive index thin film such as a SiO ₂ thin film are alternately laminated (preferably, the lower layer is a high refractive index thin film). And a laminated film having a two-layer structure in which the upper layer is a low refractive index thin film).

  The thickness of the reflective thin film is preferably 20 to 60 nm for the high refractive thin film and 50 to 200 nm for the low refractive thin film, more preferably from the viewpoint of increasing the reflectance of blue light among visible light wavelengths. The high refractive index thin film is preferably in the range of 30 to 50 nm, and the low refractive index thin film is in the range of 60 to 150 nm.

2. Application of this sheet For example, this sheet takes out an extraction electrode for applying a voltage from the outer periphery of the light control region of each transparent electrode film, and uses this to control on / off of the voltage between the transparent electrodes. Thus, it is possible to switch between the transparent mode and the cloudy mode.

  Examples of the use of this sheet include electronic curtains, display effects, and viewing angle switching sheets.

  Hereinafter, an example in the case of using this sheet as an electronic curtain will be described. That is, for example, this sheet is disposed on the front surface of a display device such as a liquid crystal display, a plasma display, or an organic EL display.

  And when the power supply of a display apparatus is off, the power supply of this sheet | seat is turned off and it is set as the cloudiness mode. At this time, the display device becomes dark or black, but the color of the sheet in the cloudy mode is whitened. Therefore, it is possible to make it difficult for the viewer to feel the presence of the present sheet and thus the display device.

  On the other hand, when the power of the display device is on, the power of the sheet is turned on to set the transparent mode. At this time, the transmitted light from the display device passes through the transparent electrode film on the non-viewing side → the liquid crystal layer → the transparent electrode film on the viewing side and is viewed by the viewer.

  At this time, if the display device is embedded in the wall, the presence of the display device can be made more inconspicuous by arranging the sheet on the wall surface.

  Hereinafter, the present invention will be described in detail using Examples and Comparative Examples. The refractive index below is a value at a wavelength of 633 nm.

1. Preparation of transparent electrode film 1.1 1-No. The transparent electrode film which concerns on No. 5 As a transparent electrode film applied to the visual recognition side of the light control film which concerns on an Example, No. 5 is used. 1-No. The transparent electrode film which concerns on 5 was produced.

Here, no. 1-No. The transparent electrode film according to No. 5 is basically a TiO ₂ thin film by a sol-gel method as a first layer on one side of a PET film, and a titanium oxide thin film (barrier thin film) / Ag as a second layer. -Bi alloy thin film / titanium oxide thin film (barrier thin film) The third layer has a transparent electrode having a three-layer structure in which TiO ₂ thin films by a sol-gel method are sequentially laminated.

  The barrier thin film is included in the Ag-Bi alloy thin film as a thin film accompanying the Ag-Bi alloy thin film, and the number of layers is counted.

  Hereinafter, no. 1-No. The specific preparation procedure of the transparent electrode film which concerns on 5 is shown.

(Preparation of coating solution)
First, a coating solution used for forming a TiO ₂ thin film by a sol-gel method was prepared. That is, tetra-n-butoxytitanium tetramer (manufactured by Nippon Soda Co., Ltd., “B4”) as titanium alkoxide, and acetylacetone as an additive that forms an ultraviolet-absorbing chelate, n-butanol and isopropyl It mix | blended with the mixed solvent with alcohol, and this was mixed for 10 minutes using the stirrer, and the coating liquid was prepared. At this time, the composition of tetra-n-butoxy titanium tetramer / acetylacetone / n-butanol / isopropyl alcohol was 6.75% by mass / 3.38% by mass / 59.87% by mass / 30.00% by mass, respectively. did.

(Preparation of transparent electrode)
As a transparent polymer film, a polyethylene terephthalate film (Toyobo Co., Ltd., “Cosmo Shine (registered trademark) A4100”) (hereinafter referred to as “PET film”) having an easy-adhesion layer formed on one side is used. Used, a TiO ₂ thin film was formed as a first layer on the surface (PET surface) side opposite to the easily adhesive layer surface side of this PET film by the following procedure.

That is, the coating liquid was continuously applied at a predetermined linear velocity on the PET surface side of the PET film using a micro gravure coater. Next, the coating film was dried at 100 ° C. for 80 seconds using an in-line drying furnace to form a precursor film of a TiO ₂ thin film. Then, using an in-line ultraviolet irradiator [high pressure mercury lamp (160 W / cm)], the precursor film was continuously irradiated with ultraviolet rays for 1.5 seconds at the same linear velocity as that during the coating. As a result, a TiO ₂ thin film was formed on the PET film by a sol-gel method.

Next, each thin film constituting the second layer was formed on the first TiO ₂ thin film.

That is, a lower titanium oxide thin film (barrier thin film) was formed by reactive sputtering on the first TiO ₂ thin film using a DC magnetron sputtering apparatus. Next, an Ag—Bi alloy thin film was formed on the lower titanium oxide thin film (barrier thin film) by sputtering. Next, an upper titanium oxide thin film (barrier thin film) was formed on this Ag—Bi alloy thin film by reactive sputtering.

At this time, the film formation conditions of the upper and lower titanium oxide thin films (barrier thin films) were as follows: Ti target (purity 4N), vacuum ultimate pressure: 5 × 10 ⁻⁶ (Torr), inert gas: Ar, reactivity Gas: O ₂ , Gas flow ratio: Ar / O ₂ = 100/20, Gas pressure: 2.5 × 10 ⁻³ (Torr), Input power: 8.3 (W / cm ² ), Film formation time: 1 .5 seconds.

The film formation conditions of the Ag—Bi alloy thin film are as follows: Ag—Bi alloy target (Bi content 0.5 atomic%), vacuum ultimate pressure: 5 × 10 ⁻⁶ (Torr), inert gas: Ar, gas pressure : 2.5 × 10 ⁻³ (Torr), input power: 1.1 (W / cm ² ), and film formation time: 1.5 seconds.

Next, as the third layer, a TiO ₂ thin film was formed by a sol-gel method on the upper titanium oxide thin film (barrier thin film) of the second layer. Here, a predetermined film thickness is obtained by performing the film formation procedure according to the first layer once.

  From the above, No. 1-No. The transparent electrode film which concerns on 5 was produced.

The refractive index of the TiO ₂ thin film (measurement wavelength 633 nm), was determined by FilmTek3000 (manufactured by Scientific Computing International, Inc.). Further, the content of the organic component contained in the TiO ₂ thin film was measured by X-ray photoelectron spectroscopy (XPS).

  Moreover, EDX analysis was performed about each titanium oxide thin film (barrier thin film), and Ti / O ratio was calculated | required as follows.

  That is, a transparent electrode film was cut out by a microtome (LKB Co., Ltd., “Ultrome V2088”), and a test piece having a thickness in a cross-sectional direction of a laminated structure including a titanium oxide thin film (barrier thin film) to be analyzed was 100 nm or less. Produced.

  Subsequently, the cross section of this test piece was confirmed with a field emission electron microscope (HRTEM) (manufactured by JEOL Ltd., “JEM2001F”).

  Next, using an EDX apparatus (resolution of 133 eV or less) (“JED-2300T” manufactured by JEOL Ltd.), an electron beam is emitted from the electron gun of this apparatus, and a titanium oxide thin film (barrier thin film) to be analyzed The elemental element of the titanium oxide thin film (barrier thin film) was analyzed by detecting the incident characteristic X-ray and analyzing it.

Moreover, Bi content in an Ag-Bi alloy thin film was calculated | required as follows. That is, under the above-described film forming conditions, a test piece in which an Ag-Bi alloy thin film is formed on a glass substrate is prepared separately, and the test piece is immersed in a 6% HNO ₃ solution and subjected to elution with ultrasonic waves for 20 minutes. Thereafter, the obtained sample solution was used for measurement by the concentration method of ICP analysis.

  Table 1 shows the No. produced. 1-No. 5 shows a detailed layer structure of a transparent electrode of the transparent electrode film according to FIG.

1.2 ITO Film An ITO film was produced by the following procedure as a transparent electrode film applied to the non-viewing side of the light management film according to the example and the viewing side and non-viewing side of the light control sheet according to the comparative example. did.

  That is, as a transparent polymer film, a polyethylene terephthalate film (Toyobo Co., Ltd., “Cosmo Shine (registered trademark) A4100”) having an easy-adhesion layer formed on one side (hereinafter referred to as “PET film”). ), An indium tin oxide (ITO) thin film (thickness 30 nm) is formed by sputtering deposition on the surface (PET surface) opposite to the easy adhesion layer side of this PET film, Produced.

1.3 Characteristics of single transparent electrode film (transmission / reflection spectrum of single transparent electrode film)
No. The transmission / reflection spectrum was measured in advance for the transparent electrode film and the ITO film alone according to 1 to 5.

  At this time, the transmission / reflection spectrum was determined by measuring a wavelength of 300 to 1000 nm every 1 nm using a spectrophotometer (manufactured by Shimadzu Corporation, “UV3100”).

  In FIG. 1, the measurement result of the transmission spectrum of each transparent electrode film single-piece | unit is shown. In FIG. 2, the measurement result of the reflection spectrum of each transparent electrode film single-piece | unit is shown. According to these, no. It can be seen that the transparent electrode films 1 to 5 have less transmission of the red component and the yellow component as compared with the ITO film. Also, the reflectance is low. On the other hand, it can be seen that the ITO film has a large amount of transmission of red and yellow components. It can also be seen that the reflectance is high and the reflected light contains a lot of blue components.

(Durability of transparent electrode film alone)
No. About the transparent electrode film single-piece | unit which concerns on 1-5, the visible light transmittance | permeability and the surface resistance value were evaluated in advance. No. About the transparent electrode film single-piece | unit which concerns on 1, the visible light transmittance | permeability and surface resistance value after heat-processing at 100 degreeC for 125 hours were further evaluated in advance.

  At this time, the visible light transmittance is measured according to JIS R3106, using a spectrophotometer (manufactured by Shimadzu Corporation, “UV3100”) to measure a transmission spectrum with a wavelength of 300 to 1000 nm, and the visible light transmittance is This was done by calculating. Further, an eddy current meter (manufactured by Coper Electronics Co., Ltd., “non-contact resistivity meter model 717”) was used for the measurement of the surface resistance value.

  In Table 2, no. The result obtained about the transparent electrode film single-piece of 1-5 is shown collectively.

  According to Table 2 above, the following can be understood. That is, no. Although the transparent electrode film which concerns on 1 has a silver alloy thin film in a transparent electrode, it turns out that the visible light transmittance | permeability hardly fluctuates even after the heating. It can also be seen that the surface resistance is low even after the initial heating.

  It is known that silver is likely to diffuse into other thin films when exposed to a heated environment. When the barrier thin film is provided, diffusion of silver constituting the silver alloy thin film can be easily suppressed, transparency to visible light and conductivity can be easily maintained for a long time, and durability and heat resistance can be excellent. It could be confirmed.

  In addition, No. The above-mentioned No. 2 to 5 transparent electrode films were also used. No. 1 having the same durability as the transparent electrode film is No. 1. No. 2-5 transparent electrode structure of transparent electrode film, No. It can be easily inferred from the result of one transparent electrode film.

2. Preparation of light control sheet (Examples 1 to 10)
Next, each transparent electrode film (Example 1 and Example 6 is No. 1, Example 2 and Example 7 is No. 2, Example 3 and Example 8 are No. 3 as the transparent electrode film on the viewing side. No. 4 is used for Examples 4 and 9, No. 5 is used for Examples 5 and 10, and an ITO film is used as a transparent electrode film on the non-viewing side, and a liquid crystal layer is sandwiched between these films. (Examples 1 to 5 have a thickness of 10 μm, Examples 6 to 10 have a thickness of 30 μm), and light control sheets according to Examples 1 to 10 were produced.

  Specifically, first, 80 parts by weight of a liquid crystal material (manufactured by Merck Co., Ltd., “nematic liquid crystal TL213”), 17.5 parts by weight of 3,5,5-trimethylhexyl acrylate, 2.5 parts by weight of hexanediol vinyl ether acrylate 1 part by weight of 2,2-dimethoxy-2-phenylacetophenone was further added as an ultraviolet initiator to prepare a liquid liquid crystal composition.

  Next, the transparent electrode surface of the predetermined transparent electrode film disposed on the viewing side and the transparent electrode surface of the predetermined ITO film disposed on the non-viewing side were opposed to each other with a predetermined gap.

  Next, the liquid crystal composition was naturally injected into the gap. Thereafter, the entire surface was irradiated with ultraviolet light uniformly to polymerize the monomer.

  The light control sheet which concerns on Examples 1-10 was produced by the above.

(Comparative Examples 1 and 2)
The light control sheet according to Comparative Example 1 is the same as the light control sheet according to Examples 1 to 5 (thickness of the liquid crystal layer: 10 μm) except that an ITO film is used as the transparent electrode film on the viewer side and the non-view side. Was made.

  Moreover, the adjustment which concerns on the comparative example 2 is carried out similarly to the light control sheet (thickness of a liquid-crystal layer: 30 micrometers) which concerns on Examples 6-10 except having used the ITO film as a transparent electrode film of a visual recognition side and a non-visual recognition side. A light sheet was produced.

3. Checking the color of the light control sheet The electrode was taken out from one of the short sides of each light control sheet (5 cm × 10 cm), and AC 60 Hz · 12 V was applied to make each light control sheet a cloudy mode.

  Then, the visible light scattering reflection spectrum of each light control sheet in the cloudiness mode was measured using a spectrophotometer. The results are shown in FIGS.

  Moreover, based on JIS R3106 and JIS Z8722, the visible light scattering reflectance and the color coordinate of the reflected color were measured. The results are shown in Table 3.

4). Discussion According to FIGS. 1 to 4 and Table 3, the following can be understood. That is, the light control sheet according to the comparative example uses an ITO film as the transparent electrode film on both the viewing side and the non-viewing side.

  Therefore, the visible light scattered / reflected light has a large amount of yellow and red components, and as a result, it can be seen that the viewer looks yellowish in the cloudy mode.

  On the other hand, the light control sheet which concerns on an Example uses the transparent electrode film which has a specific transparent electrode for all at the visual recognition side, and uses the ITO film at the non-visual recognition side. Therefore, the yellow component and the red component contained in the visible light scattered / reflected light are small, and the blue component is large. As a result, the reflected color in the cloudy mode shifted to the blue side, the yellowish color disappeared, and the color could be whitened.

  Moreover, when Examples were compared with each other, by increasing the thickness of the liquid crystal layer, the visible light scattering reflectance was increased, and the apparent whiteness could be further improved.

  Further, it was found that the reflectance of red / yellow light can be further reduced by reducing the thickness of the metal oxide thin film in the transparent electrode film on the viewing side.

  Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention. .

No. It is the figure which showed the measurement result of the transmission spectrum of 1-5 transparent electrode films single-piece | unit and ITO film single-piece | unit. No. It is the figure which showed the measurement result of the reflection spectrum of 1-5 transparent electrode films single-piece | unit and ITO film single-piece | unit. It is the figure which showed the measurement result of the visible light scattering reflectance of the light modulation sheet which concerns on Examples 1-5 and Comparative Example 1. FIG. It is the figure which showed the measurement result of the visible light scattering reflectance of the light modulation sheet which concerns on Examples 6-10 and the comparative example 2. FIG.

Claims (10)

A light control sheet comprising a pair of transparent electrode films arranged so that the transparent electrodes of each other face each other, and a liquid crystal layer sandwiched between the transparent electrodes,
The transparent electrode film placed on the viewer side is
A metal oxide thin film, a metal thin film, and a metal oxide thin film are laminated in this order on the surface of the transparent polymer film on the liquid crystal layer side,
The transparent electrode film placed on the side opposite to the viewing side is
A light control sheet, wherein a composite oxide thin film of indium and tin is laminated on a surface of a transparent polymer film on a liquid crystal layer side.   The light control sheet according to claim 1, wherein the metal oxide thin film is a titanium oxide thin film.   The light control sheet according to claim 1, wherein the metal thin film is a silver thin film or a silver alloy thin film.   The light control sheet according to claim 1, wherein the metal oxide thin film contains an organic component.   The light control sheet according to any one of claims 1 to 4, wherein a barrier thin film mainly composed of a metal oxide is further formed on at least one surface of the metal thin film.   The light control sheet according to claim 5, wherein the metal oxide constituting the barrier thin film is titanium oxide.   The transparent electrode film disposed on the side opposite to the viewing side has a reflective thin film laminated on a surface opposite to the surface on the liquid crystal layer side of the transparent polymer film. The light control sheet | seat in any one.   The light control sheet according to claim 1, wherein the light control sheet is disposed on a front surface of the display device.   The light control sheet according to claim 8, wherein the display device is installed in a wall.   The thickness of the said metal oxide thin film exists in the range of 5-60 nm, The light control sheet in any one of Claim 1 to 9 characterized by the above-mentioned.

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