JP4934909B2 - Method for manufacturing electrochromic display medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display medium such as a card having a reversible display portion that can be electrically recorded and erased.
[0002]
[Prior art]
Conventionally, in a display medium such as a card, a method of forming a display layer on a display medium such as a card using a thermoreversible material capable of repeatedly writing and erasing information by heat is easy to manufacture. It is widely used in terms of
[0003]
This display layer utilizes the fact that an organic low molecular weight substance is dispersed in a resin, a transparent state and a cloudy state are reversibly changed by heating, and the two forms are maintained even at room temperature.
[0004]
However, depending on the use frequency and the use environment, if writing and erasing are repeated, the reflection density of the display layer is not changed and becomes unreadable and there is a problem with repeated durability. Furthermore, as a display form, only transparent and cloudy contrast is provided, and multicolor display is difficult.
[0005]
A method of laminating magnetic powder instead of a thermoreversible material and magnetizing and displaying the magnetic powder has also been proposed, but there is still a problem with repeated resistance.
[0006]
Based on these, in recent years, display elements using electrochemical reactions such as electrochromic display elements have attracted attention. The electrochromic display element is excellent in repeated resistance, and multicolor display is possible by selecting an electrochromic material.
[0007]
However, as an electrochromic display element, a nonaqueous electrolytic solution such as a combination of lithium perchlorate and propylene carbonate is used and sealed in a cell.
[0008]
Thus, the electrochromic element in which the electrolytic solution is sealed in the cell does not have flexibility, so that it is difficult to adapt as a display medium such as the aforementioned card.
[0009]
As a solution to this problem, a so-called gel type polymer electrolyte in which a matrix polymer is swollen with a solution in which a supporting electrolyte is dissolved in a solvent as an electrolyte has been used.
[0010]
Specifically, propylene carbonate, γ-butyrolactan, acetonitrile or the like is used as the solvent, and as the supporting electrolyte, quaternary alkyl ammonium ions, lithium ions, sodium ions, alkyl phosphoniums are often used as cations, and as anions. In this case, halogen ion, nitrate ion, BF ₄ or the like is used.
[0011]
As the polymer, a polymer having an ionic group in the molecule, such as polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyethyleneimine, and polyphosphazene is used.
[0012]
[Problems to be solved by the invention]
However, when a gel type polymer electrolyte impregnated with a liquid electrolyte is used, leakage of the electrolyte occurs when pressure is applied to the reversible display area, damage to the equipment, and the solvent is contained in the matrix polymer. There is a problem that the properties as an electrolyte change due to coming out of the above, and there is a problem that it lacks long-term reliability.
[0013]
Further, sealing for preventing liquid leakage is necessary, and the degree of freedom is limited with respect to the form of the display unit.
[0014]
An object of the present invention is to provide an electrochromic display medium which eliminates the disadvantages of conventional display media such as cards, has excellent repeatability, and has a high degree of freedom with respect to the form of the display unit without impairing performance such as flexibility. The purpose is to provide.
[0015]
[Means for Solving the Problems]
The invention according to claim 1 is a method of manufacturing a display medium having a reversible display portion that can be electrically recorded and erased on at least a flexible light-transmitting substrate, wherein the polycrystal previously dissolved in a solvent is used. A step of preparing a polymer solid electrolyte material by adding a supporting electrolyte and a viologen compound previously dissolved in a solvent to a matrix polymer having an ether skeleton, and the polymer solid electrolyte material comprising a flexible electrode having a transparent electrode Forming a polymer solid electrolyte layer on the transparent translucent substrate by coating, and forming another flexible translucent substrate having a transparent electrode on the polymer solid electrolyte layer. And a laminating step . A method for producing an electrochromic display medium.
[0016]
The invention according to claim 2 is the method for producing an electrochromic display medium according to claim 1, wherein polymerizable polyalkylene oxide is added as a crosslinking agent in the step of preparing the polymer solid electrolyte material. .
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Details of the present invention will be described below. The display medium according to the present invention is not particularly limited and can be applied to various media. Here, an example applied to a card with good handling will be described.
[0031]
When a solid electrolyte is used for an electrochromic display element, a separator impregnated with the electrolyte is not required, and the manufacture of the element can be simplified.At the same time, there is no risk of performance degradation due to liquid leakage, etc. Can be manufactured.
[0032]
The electrochromic display medium of the present invention is a display medium having a reversible display portion that can be electrically recorded and erased, sandwiched between two electrodes, on at least a flexible translucent substrate, The reversible display portion is at least an electrochromic material layer and a polymer solid electrolyte layer having a polyether skeleton in which a supporting electrolyte is dissolved, or a polymer solid electrolyte having a polyether skeleton in which an electrochromic material and a supporting electrolyte are dissolved. Including a reversible display portion consisting of a plurality of layers. Although the layer structure is not particularly limited, for example, a reversible display portion made of an electrochromic material or a polymer solid electrolyte is sandwiched between two electrodes, and a flexible base material is laminated on the outside thereof. The thing which becomes. Further, at least one of the electrode and the flexible substrate may be translucent, and the other may be in any form such as translucency, translucency, semi-translucency, and reflectivity. .
[0033]
The flexible translucent substrate used in the present invention is not particularly limited, and any material may be used as long as it has flexibility and translucency. For example, polyethylene terephthalate (hereinafter referred to as PET), polypropylene, cycloolefin polymer, polyamide, polyether sulfone, polymethyl methacrylate, polycarbonate and the like can be used. Moreover, as a flexible light-impermeable base material, a flexible semi-light-transmissive base material, and a flexible reflective base material, a well-known material, for example, a light-transmissive, semi-light-transmissive plastic, a metal material, A film provided with a metal thin film can be used.
[0034]
As the transparent electrode, a composite oxide of indium and tin (hereinafter referred to as ITO), a composite oxide of indium and zinc, a composite oxide of aluminum and zinc, or the like can be used. Moreover, well-known materials, such as a metal material, can be used as an opaque electrode, a semi-transparent electrode, and a reflective electrode.
[0035]
In the present invention, a polymer solid electrolyte is used as the solid electrolyte. The polymer solid electrolyte is advantageous in that it is excellent in processability and moldability, the obtained solid electrolyte is flexible, and a thin film can be formed.
[0036]
The solid polymer electrolyte in the present invention is characterized in that it has a polyether skeleton in part as a matrix polymer. Here, examples of the polyether include polyethylene oxide, polypropylene oxide, glycerin polyether, silicone polyether, acrylic poly Examples include ether and phosphazene polyether. Of these, polyethylene glycol and polypropylene oxide are preferable because they are relatively available and have excellent processability.
[0037]
In addition, by adding a polymerizable polyalkylene oxide as a cross-linking agent to the above polyether and cross-linking it, the film strength of the polymer solid electrolyte can be improved and the ion conductivity at room temperature can be improved. It is.
[0038]
Here, as the polymerizable polyalkylene oxide, acrylate derivatives, methacrylate derivatives, and vinyl derivatives of polyalkylene glycol are suitable. Specifically, methoxyethylene glycol mono (meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate, Octoxy polyethylene glycol-block-polypropylene glycol mono (meth) acrylate, lauroxy polyethylene glycol mono (meth) acrylate, stearoxy polyethylene glycol mono (meth) acrylate, allyloxy polyethylene glycol mono (meth) acrylate, nonylphenoxy polyethylene glycol mono (Meth) acrylate, nonylphenoxypolypropylene glycol mono (meth) acrylate, nonylpheno Sipoly (ethylene glycol-propylene glycol) mono (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyethylene glycol block Polypropylene glycol block Polyethylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, poly (ethylene glycol-tetramethylene glycol) di (meth) acrylate, poly (propylene glycol-tetramethylene glycol) di ( And (meth) acrylate. In addition, ethylene oxide-modified bisphenol A di (meth) acrylate, ethylene oxide-propylene oxide-modified bisphenol A di (meth) acrylate, and propylene oxide-tetramethylene oxide-modified bisphenol A in which block chains k and m are bonded with bisphenol A. Examples include di (meth) acrylate, ethylene oxide-block-propylene oxide-modified bisphenol A di (meth) acrylate, and the like.
[0039]
The method for crosslinking these polymerizable polyalkylene oxides can be carried out by a known method such as thermal crosslinking, ultraviolet irradiation, electron beam irradiation, and is not particularly limited. Moreover, there is no restriction | limiting also regarding adding a peroxide, a photoinitiator, etc. as a crosslinking adjuvant by a crosslinking method.
[0040]
The molecular weight of the matrix polymer of the solid electrolyte in the present invention is required to be 10,000 or more. When the molecular weight is small, the crystallinity of the polymer solid electrolyte is increased, resulting in a decrease in ion conductivity, and at the same time, sufficient film strength cannot be obtained when laminated as a display member on a display medium. .
[0041]
The glass transition temperature Tg of the polymer solid electrolyte material in the present invention is desirably −40 ° C. or lower. This is because, for example, when a Li-based compound is used for the supporting electrolyte, lithium ions dissociated into the matrix polymer create an association with oxygen in the polymer, solvate, and repeatedly apply association and dissociation by applying an electric field. However, at this time, ions move by changing the local arrangement of polymer chains due to the thermal motion of the amorphous layer. Therefore, it is necessary to select one having a low glass transition temperature. When Tg is high, ion conductivity at room temperature is lowered and sufficient display performance cannot be exhibited.
[0042]
The residual solvent amount of the polymer solid electrolyte material in the present invention needs to be 1% by weight or less. When the amount of the residual solvent is large, the ion conductivity is lowered and the adhesion and adhesion to the electrode are deteriorated.
[0043]
In the mechanical properties of the polymer solid electrolyte material in the present invention, the tensile elastic modulus in the static tensile test needs to be 10,000 Pa to 100,000,000 Pa. In particular, 50,000 Pa to 50,000,000 Pa is more preferable. For example, when it is used as a display member for a card, it is assumed that the card is used in a situation with a certain degree of deformation. Therefore, the tensile elastic modulus in the above range is required. However, if the tensile modulus is too high, the solid electrolyte layer becomes hard and brittle, and the mechanical resistance is poor. Further, when the tensile elastic modulus is low, flexibility can be imparted, but handling becomes worse. From the above points, a tensile elastic modulus within the above range is desirable.
[0044]
The supporting electrolyte in the present invention refers to an electrolyte salt compound added to the matrix polymer.
As the supporting electrolyte, LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiPF ₆ , LiI, LiBr, LiSCN, LiN (CF ₃ SO ₂ ) ₂ , NaI, Li ₂ B ₁₀ Cl ₁₀ , LiCF ₃ CO ₂ , NaBr, NaSCN, KSCN, MgCl ₂ , Mg (ClO ₄ ) ₂ , (CH ₃ ) ₄ NBF ₄ , (CH ₃ ) ₄ NBr, (C ₂ H ₅ ) ₄ NClO ₄ , (C ₂ H ₅ ) ₄ Ni , (C ₃ H ₇ ) ₄ NBr, (n-C ₄ H ₉ ) ₄ NClO ₄ , (n-C ₄ H ₉ ) ₄ Ni, (n-C ₅ H ₁₁ ) ₄ Ni, and the like. Among these, Li salts such as LiClO ₄ , LiPF ₆ , and LiBF ₄ are more preferable.
[0045]
In the present invention, the usage amount of the supporting electrolyte is desirably 10 to 50% by weight, preferably 20 to 40% by weight, based on the weight of the matrix polymer. When the amount of the supporting electrolyte is small, the ionic conductivity is low, and when it is large, the workability, formability, and mechanical strength are lowered.
[0046]
Electrochromic materials that are colored or decolored by an electrical redox reaction in the present invention include inorganic molecules such as WO ₃ and V ₂ O ₅ , low molecular weight compounds such as viologen dyes, aromatic amine dyes, and anthraquinone dyes. A pigment | dye etc. can be used. Of these, the method of vacuum-depositing tungsten oxide on the electrode is preferable because, for example, when a display element is stacked on a card, it can be formed relatively easily.
[0047]
A viologen compound is also preferable because it can be easily prepared by dissolving it in advance in a polymer solid electrolyte alone or in a solvent such as methanol.
[0048]
Further, by patterning the electrochromic material, the transparent electrode, the non-translucent electrode, the semi-transparent electrode, or the reflective electrode, display portions having various patterns such as segments can be obtained. Moreover, a well-known technique can be used for the patterning method.
[0049]
It is considered that a so-called general film forming method can be applied to the method for producing an electrochromic display medium using a polymer solid electrolyte in the present invention. Regarding mixing of the polymer and the supporting electrolyte, a method of mixing mechanically and a method of dissolving in a solvent and mixing to remove the solvent can be considered.
[0050]
When a solvent is used, various polar solvents such as acetone, acetonitrile, chloroform, methyl ethyl ketone, tetrahydrofuran and the like are used alone or in combination. Although it does not restrict | limit especially regarding the density | concentration of a solution, When considering the film thickness after film forming etc., 5 to 40 weight% is preferable.
[0051]
As a film-forming method using a solvent, a solution in which a polymer and a supporting electrolyte are dissolved is directly applied to an electrode by a die coater or a spin coat and dried. A method of laminating the formed solid electrolyte membrane between the electrodes is conceivable. In the case of laminating, since the manufacturing process increases and the cost increases due to the use of release paper, the direct coating method is more preferable.
[0052]
Various kneaders, open rolls, extruders, and the like are conceivable as the mechanical mixing method. The mixed polymer solid electrolyte material can be formed by extrusion using a general T die and calendering.
[0053]
By using these molding methods that do not use a solvent, it is not necessary to recover the solvent used, and it is possible to reduce the cost and manufacture with less burden on the environment.
[0054]
【Example】
Examples of the present invention will be described below by examples applied to a card, but the present invention is not limited to these examples.
[0055]
As a layer configuration, a polymer solid electrolyte film in which a supporting electrolyte is dissolved is laminated between transparent electrodes obtained by depositing ITO on a polyester substrate.
[0056]
One of the features of the present invention is the high degree of freedom regarding the form of the display member. For example, an electrochromic material is partially deposited by masking or the like on a film in which an ITO transparent electrode is deposited on a polyester base material. It shows that it is possible to laminate the polymer electrolyte only on the part.
[0057]
When a gel type polymer electrolyte is used, when the polymer electrolyte is partially laminated, it is difficult to seal only the display portion, and it is necessary to seal the entire card. The invention is excellent.
[0058]
<Example 1>
Commercially available acetonitrile (Kanto Chemical Co., Ltd .: special grade) was used as a solvent, and 20% by weight of polyethylene oxide (molecular weight 500,000) was dissolved therein. LIBF ₄ was added at a ratio of 40 to 100 parts by weight of the polymer, and a solution obtained by dissolving methyl viologen in ethanol was added so that the ratio of methyl viologen was 1 with respect to 100 parts by weight of the polymer. Defoamed to obtain a coating solution.
[0059]
The coating solution was applied to a commercially available PET / ITO film (Nitto Denko Corporation, Electrister 300-O) with a bar coater and dried at 80 ° C. for 5 minutes to form a polymer solid electrolyte membrane. Thereafter, the same PET / ITO film as described above was laminated on the solid electrolyte membrane, and then the laminate was cut out to a general card size (85 mm × 57 mm).
[0060]
With respect to the produced card, an electrode was attached, and a color change when a charge of 3 V was applied was observed, and the cycle resistance was observed.
[0061]
<Example 2>
By masking the PET / ITO film, vacuum deposition is performed under the conditions of a vacuum degree of 3 × 10 ⁻⁵ torr, an acceleration voltage of 6 keV, a current of 10 to 20 mA, and a film forming speed of 1.5 to 2 nm. Vacuum-deposited into shape.
[0062]
The polymer solid electrolyte was obtained by extruding a sample obtained by kneading polyethylene oxide and LIBF ₄ with an open roll at a kneading temperature of 80 ° C. using a T die at a processing temperature of 120 ° C. As release paper, commercially available release PET (Tosero Co., Ltd. Release PET: 03-3)
8-MB), a solid polymer electrolyte membrane could be formed on the release paper with a uniform thickness.
[0063]
The above-mentioned star-shaped tungsten oxide vapor-deposited PET / ITO film was cut into a card shape, and a polymer solid electrolyte film and PET / ITO film cut into a size covering the star shape were laminated to obtain a laminate. A schematic diagram is shown in FIG. About this laminated body, the electrode was attached like Example 1, the color change at the time of applying the electric charge of 3V was observed, and the cycle tolerance was observed.
[0064]
It was confirmed that the film was colored by applying an electric charge in both Example 1 and Example 2. The time required for the optical reflection density to reach 1 was about several seconds. The colored sample did not lose its color when observed after 2 hours, and had a memory property.
[0065]
In Example 2, the appearance of coloring in a star shape deposited with tungsten oxide was observed.
[0066]
Moreover, by changing the electrode and applying a reverse charge, it was confirmed that the color disappeared, and it returned to the initial state in about several seconds. This coloring and decoloring were repeated to examine the cycle resistance, but no deterioration was observed in the observation up to 1000 cycles, and the initial display characteristics were maintained.
[0067]
【Effect of the invention】
As is clear from the above explanation, according to the present invention, by using a polymer solid electrolyte having a polyether skeleton as an electrolyte material and having a supporting electrolyte dissolved therein, the repetition resistance is high, there is no liquid leakage, and the like. An electrochromic display medium that does not impair flexibility can be easily manufactured.
[0068]
In addition, when the present invention is applied to a card, as is apparent from the examples, the present invention has a higher degree of freedom with respect to the form of the display unit than the conventional card with a display unit, and simply laminating. A card with a display unit could be manufactured.
[0069]
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of a card according to a second embodiment.
DESCRIPTION OF SYMBOLS 1 ... Flexible translucent base material 2 ... Transparent electrode layer 3 ... Polymer solid electrolyte layer 4 ... Electrochromic layer

Claims (2)

A method of manufacturing a display medium having a reversible display portion that can be electrically recorded and erased on at least a flexible translucent substrate , and supported by a matrix polymer having a polyether skeleton previously dissolved in a solvent A step of preparing a polymer solid electrolyte material by adding an electrolyte and a viologen compound previously dissolved in a solvent, and coating the polymer solid electrolyte material on one flexible translucent substrate having a transparent electrode. Forming a polymer solid electrolyte layer by a method, and laminating another flexible translucent substrate having a transparent electrode on the polymer solid electrolyte layer. A method for producing an electrochromic display medium. The method for producing an electrochromic display medium according to claim 1, wherein a polymerizable polyalkylene oxide is added as a crosslinking agent in the step of preparing the polymer solid electrolyte material .

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