JP5689071B2 - Electrochromic material - Google Patents

Description

  The present invention relates to an electrochromic material, and more particularly to an electrochromic material comprising a hyperbranched polymer having a compound that exhibits electrochromic properties as a polymer portion.

  An electrochromic element applied to a light control element or a display element is an element that utilizes a phenomenon called electrochromism in which a redox reaction occurs reversibly when a voltage is applied and is reversibly colored or colorless. This electrochromic element is generally composed of an element in which, for example, a transparent electrode substrate, an electrochromic layer, and a counter electrode substrate are sequentially provided.

  Until now, inorganic compounds such as tungsten oxide have been known as compounds having electrochromic properties (Patent Document 1), and the inorganic oxide is deposited on a transparent electrode by vacuum deposition or sputtering. A method for manufacturing an electrochromic device has been proposed. However, this manufacturing method requires a vacuum technique at the time of film formation, and there is a problem that costs increase.

As an element that can be manufactured by a cheaper and simpler manufacturing process, various electrochromic elements using, for example, an organic electrochromic compound made of a viologen derivative or the like have been proposed.
For example, a green electrochromic display viologen compound (Patent Document 2), an electrochromic mirror using a polymer compound having a viologen structure (Patent Document 3), a precursor component of a polymer solid electrolyte and a reactive viologen compound. An electrochromic element (Patent Document 4) provided with an electrolyte layer obtained by polymerization, an electrochromic element using a polymer type electrochromic compound (Patent Document 5), and the like have been proposed.

  Furthermore, a triazine ring-containing multi-branched polymer that exhibits electrochromic properties by cation doping (Patent Document 6), and a core-shell type having a functional layer composed of a functional functional group having an electrochromic function on the outer peripheral portion Electrochromic device (Patent Document 7) having a microsphere (the microsphere is, for example, a dendrimer or a hyperbranched polymer), and a hyperbranched polymer (Patent Document 8) having a compound exhibiting electrochromic properties as a polymer portion The application of hyperbranched polymers to electrochromic devices has also been proposed.

JP-A-63-18336 JP-A-5-170738 Japanese Patent Laid-Open No. 11-38454 Japanese Patent Laid-Open No. 11-183940 Japanese Patent Laid-Open No. 11-183941 Japanese Patent Laid-Open No. 9-302073 JP 2003-121883 A International Publication No. 2009/136626 Pamphlet

The organic electrochromic compounds that have been proposed so far are compared with those of conventional liquid crystal display devices in terms of response speed, coloring efficiency, and repetitive stability, particularly from the viewpoint of application to display devices. Therefore, further improvement in performance was required.
Moreover, in the above-mentioned hyperbranched polymer type organic electrochromic compound, the solubility in various organic solvents is low, and usable solvents are limited, and it is difficult to form a thin film at the time of device fabrication. There was a problem.
On the other hand, a polymer type electrochromic compound using a copolymer of a monofunctional polymerizable monomer has advantages such as high solubility in various solvents and easy formation of a thin film. Since the density of the part is lowered, problems such as a decrease in contrast remain. Moreover, even if the copolymer is highly branched in order to increase the density of the electrochromic site, the reaction conditions are strict in the ordinary hyperbranched polymer manufacturing method, the procedure is complicated, and the production cost is high. Even if a polymer is obtained, there is a problem that a practical response speed and coloring efficiency as an electrochromic compound are not provided.

  The present invention has been made in view of such circumstances, has a high response speed, has high coloring efficiency, is excellent in repeated stability, can be used for a long time, and has excellent solubility in various solvents. Furthermore, it aims at providing the electrochromic material which manufacture is easy.

  As a result of intensive studies in order to achieve the above object, the present inventors have determined that a monomer having an electrochromic property in the same molecule and a monomer having two or more radical polymerizable double bonds to the monomer. The present inventors have found that a hyperbranched polymer obtained by polymerizing in the presence of a polymerization initiator in an amount of 20 to 300 mol% can be a polymer material having excellent electrochromic properties and solubility.

That is, as a first aspect, the present invention provides a monomer A having a portion exhibiting electrochromic properties and two or more radical polymerizable double bonds in the same molecule in an amount of 20 to 300 mol% relative to the monomer A. The present invention relates to an electrochromic material comprising a hyperbranched polymer obtained by polymerization in the presence of the polymerization initiator B.
As a second aspect, the monomer A having a moiety that exhibits electrochromic properties in the same molecule and two or more radical polymerizable double bonds is a compound represented by the following formula (1): The electrochromic material described in 1.
[Wherein, R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and A ¹ and A ² each independently represent an alkyl group having 1 to 1 carbon atoms which may contain an ether bond or an ester bond. 14 represents a divalent hydrocarbon residue, and E represents a portion that exhibits electrochromic properties. ]
As a third aspect, the present invention relates to the electrochromic material according to the second aspect, wherein A ¹ and A ^{2 in the} formula (1) are structures represented by any of the following formulas (2) to (5).
[Wherein, p, q, r and s are repeating numbers, each independently represents an integer of 1 to 6, and * is a side linked to E which is a portion that develops electrochromic properties. ]
As a fourth aspect, the present invention relates to the electrochromic material according to the second aspect, in which the monomer A represented by the formula (1) is a compound represented by the following formula (6).
[In formula, E represents the same meaning as said Formula (1). ]
As a fifth aspect, the part E expressing the electrochromic property in the formula (6) is a quaternary bipyridinium salt structure part, a 1,4-diacetylbenzene structure part, a terephthalic acid diester structure part, or biphenyl-4. , 4′-dicarboxylic acid diester structure-related electrochromic material according to the fourth aspect.
As a sixth aspect, the present invention relates to the electrochromic material according to the fifth aspect, wherein the portion E that exhibits the electrochromic characteristics in the formula (6) has a structure represented by the following formula (7).
[Wherein R ^{3 to} R ¹⁰ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. And X ⁻ and Y ⁻ are each independently Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CH ₃ COO ⁻ , PhSO ₃ ⁻ , p-TolSO ₃ ⁻ or R. ²⁷ represents SO ₄ ^— (wherein Ph represents a phenyl group, p-Tol represents a para-tolyl group, and R ²⁷ represents a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms. Represents a group). ]
As a seventh aspect, the present invention relates to the electrochromic material according to the fifth aspect, in which the part E expressing the electrochromic property in the formula (6) is represented by the following formula (8).
[Wherein R ^{11 to} R ¹⁴ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ]
As an eighth aspect, the present invention relates to the electrochromic material according to the fifth aspect, in which the portion E expressing the electrochromic property in the formula (6) is represented by the following formula (9).
[Wherein, R ^{15 to} R ¹⁸ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ]
As a ninth aspect, the present invention relates to the electrochromic material according to the fifth aspect, in which the portion E expressing the electrochromic property in the formula (6) is represented by the following formula (10).
[Wherein, R ^{19 to} R ²⁶ each independently represents a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ]
As a tenth aspect, the present invention relates to the electrochromic material according to any one of the first aspect to the ninth aspect, in which the polymerization initiator B is an azo polymerization initiator.
As an eleventh aspect, the present invention relates to the electrochromic material according to the tenth aspect, in which the polymerization initiator B is dimethyl 2,2′-azobisisobutyrate.
As a twelfth aspect, the weight average molecular weight (Mw) measured by gel permeation chromatography of the hyperbranched polymer is 1,000 to 2,000,000 in terms of polyethylene glycol, or 1,000 to 200,000 in terms of polystyrene. The electrochromic material according to any one of the first to eleventh aspects, which is 000.
As a thirteenth aspect, the monomer A represented by the following formula (6) having a portion that exhibits electrochromic properties is polymerized in the presence of a polymerization initiator B in an amount of 20 to 300 mol% with respect to the monomer A. It is related with the hyperbranched polymer obtained by making it.
[In formula, E represents the part which expresses an electrochromic characteristic. ]
As a fourteenth aspect, the present invention relates to the hyperbranched polymer according to the thirteenth aspect, in which the part E expressing the electrochromic property in the formula (6) is a structure represented by the following formula (7).
[Wherein R ^{3 to} R ¹⁰ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. And X ⁻ and Y ⁻ are each independently Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CH ₃ COO ⁻ , PhSO ₃ ⁻ , p-TolSO ₃ ⁻ or R. ²⁷ represents SO ₄ ^— (wherein Ph represents a phenyl group, p-Tol represents a para-tolyl group, and R ²⁷ represents a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms. Represents a group). ]
As a fifteenth aspect, the present invention relates to the hyperbranched polymer according to the thirteenth aspect, in which the part E expressing the electrochromic property in the formula (6) is a structure represented by the following formula (8).
[Wherein R ^{11 to} R ¹⁴ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ]
As a sixteenth aspect, the present invention relates to the hyperbranched polymer according to the thirteenth aspect, in which the part E expressing the electrochromic property in the formula (6) is a structure represented by the following formula (9).
[Wherein, R ^{15 to} R ¹⁸ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ]
As a seventeenth aspect, the present invention relates to the hyperbranched polymer according to the thirteenth aspect, in which the part E expressing the electrochromic property in the formula (6) is a structure represented by the following formula (10).
[Wherein, R ^{19 to} R ²⁶ each independently represents a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ]
As an eighteenth aspect, the present invention relates to a varnish characterized in that the electrochromic material according to any one of the first aspect to the twelfth aspect is dissolved or dispersed in at least one solvent.
As a nineteenth aspect, the present invention relates to a thin film structure containing the electrochromic material according to any one of the first to twelfth aspects.
As a twentieth aspect, an electro in which a thin film-like structure containing the electrochromic material according to any one of the first aspect to the twelfth aspect is sandwiched between two electrode layers, at least one of which is transparent. The present invention relates to a chromic element.

  The electrochromic material of the present invention has a fast response speed, high coloring efficiency, excellent repetitive stability, and electrochromic characteristics that can be used for a long time. In particular, the electrochromic material of the present invention can increase coloring efficiency by incorporating an electrochromic site into a highly branched polymer, and can provide high contrast even when the film thickness is reduced. Response speed can be improved by thinning.

  In addition, the electrochromic material of the present invention is easy to manufacture because it can be synthesized in one step from a monomer having an electrochromic moiety introduced. Also, by taking advantage of the characteristics of a polymer compound, it can be made into a thin film by a simple coating / drying operation. It is possible to form the structure. Moreover, since the electrochromic material of the present invention is soluble not only in N, N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) but also in alcohol or water, the varnish of the varnish is not limited. Thus, a thin film structure can be formed. Furthermore, the electrochromic material of the present invention can form a thin film-like structure not only on a normal flat plate-like substrate but also on a flexible film-like substrate. It is also possible to produce a chromic element.

FIG. 1 is a cross-sectional view showing an example of the configuration of an electrochromic element manufactured using the electrochromic material of the present invention. FIG. 2 is a cross-sectional view showing another configuration example of an electrochromic element manufactured using the electrochromic material of the present invention. FIG. 3 is a diagram showing a TEM image of the hyperbranched polymer synthesized in Example 1. FIG. 4 shows the time change of absorbance at a wavelength of 530 nm when a positive voltage or a negative voltage is applied to an electrochromic cell (EC color-developing layer film thickness: about 200 nm) using the hyperbranched polymer 1 prepared in Example 6. It is a figure shown (refer Example 7). FIG. 5 is a view showing the flexibility of the flexible electrochromic device using the hyperbranched polymer 1 produced in Example 8. FIG. 6 is a diagram showing the EC layer thickness dependence of the current-voltage characteristics of EC cells A and C produced in Example 9 (see Example 10). FIG. 7 is a diagram showing the EC layer thickness dependence of the transmittance of EC cells A and C created in Example 9 (see Example 11). FIG. 8 is a graph showing the applied voltage dependence of the absorbance of EC cell B prepared in Example 9 (see Example 12). FIG. 9 is a graph showing the applied voltage dependence of the color development response speed of the EC cell C created in Example 9 (see Example 13). FIG. 10 is a diagram showing the time change of absorbance at a wavelength of 550 nm when a positive voltage or a negative voltage is applied to the EC cell C created in Example 9 (see Example 14).

  In the electrochromic material of the present invention, a monomer A having a portion exhibiting electrochromic properties and two or more radical polymerizable double bonds in the same molecule is polymerized in an amount of 20 to 300 mol% with respect to the monomer A. It is a highly branched polymer obtained by polymerizing in the presence of initiator B. The hyperbranched polymer of the present invention is a so-called initiator fragment-incorporating hyperbranched polymer, and has a fragment of the polymerization initiator B used for polymerization at the terminal.

<Monomer A>
In the present invention, the monomer A has a portion that expresses electrochromic properties in the same molecule, and two or more vinyl groups or (meth) acryl groups, or a combination of both. It is preferable that it is a compound, More preferably, it is a compound represented by the said Formula (1).

In the formula (1), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and A ¹ and A ² each independently represent a carbon atom that may contain an ether bond or an ester bond. It represents a divalent hydrocarbon residue of formulas 1 to 14, and E represents a moiety that exhibits electrochromic properties.
The A ¹ and A ² preferably represent structures represented by the formulas (2) to (5), and in the formulas (2) to (5), p, q, r, and s are repeating numbers. Each independently represents an integer of 1 to 6, and * is the side linked to E, which is a part that develops electrochromic properties.
Especially, as the monomer A represented by the said Formula (1), the compound represented by the said Formula (6) is preferable (In Formula (6), E represents the part which expresses an electrochromic characteristic).

  In the present invention, the portion E that exhibits electrochromic properties is a quaternary bipyridinium salt structure portion, a 1,4-diacetylbenzene structure portion, a terephthalic acid diester structure portion, or a biphenyl-4,4′-dicarboxylic acid diester. Specifically, examples of the structure include structures represented by the formulas (7) to (10).

In the formula (7), R ^{3 to} R ¹⁰ are each independently a hydrogen atom, a linear, branched or cyclic group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represents an alkyl group, and X ⁻ and Y ⁻ are each independently Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CH ₃ COO ⁻ , PhSO ₃ ⁻ , p-TolSO _3. ^- or R ²⁷ SO ₄ ^- represents a. In the above formula, Ph represents a phenyl group, p-Tol represents a para-tolyl group, and R ²⁷ represents a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms.
R ^{11 to} R ¹⁴ in the formula (8), R ^{15 to} R ¹⁸ in the formula (9), and R ^{19 to} R ²⁶ in the formula (10) are each independently a hydrogen atom. Or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond.

R ^{3 to} R ¹⁰ and R ^{27 in} the formula (7), R ^{11 to} R ¹⁴ in the formula (8), R ^{15 to} R ¹⁸ in the formula (9), and the formula (10) Specific examples of the linear alkyl group for R ^{19 to} R ²⁶ include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-hexyl group. Specific examples of the branched alkyl group include isopropyl group, isobutyl group, 2-methylpropyl group and the like.
Furthermore, examples of the cyclic alkyl group include alicyclic aliphatic groups having a monocyclic, polycyclic or bridged cyclic structure having 3 to 30 carbon atoms. Specific examples include groups having a monocyclo, bicyclo, tricyclo, tetracyclo, pentacyclo structure or the like having 3 or more carbon atoms.

<Polymerization initiator B>
As the polymerization initiator B in the present invention, an azo polymerization initiator is preferably used.
Examples of the azo polymerization initiator include compounds shown in the following (1) to (5).
(1) Azonitrile compound:
2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 1,1′-azobis ( 1-cyclohexanecarbonitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2- (carbamoylazo) isobutyronitrile and the like;
(2) Azoamide compound:
2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [2- ( 1-hydroxybutyl)] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis [N- (2-propenyl) -2- Methylpropionamide], 2,2′-azobis (N-butyl-2-methylpropionamide), 2,2′-azobis (N-cyclohexyl-2-methylpropionamide) and the like;
(3) Cyclic azoamidine compound:
2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2′-azobis [2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) Propane], 2,2′-azobis (1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride and the like;
(4) Azoamidine compound:
2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] tetrahydrate, etc .;
(5) Other:
Dimethyl 2,2′-azobisisobutyrate, 4,4′-azobis-4-cyanovaleric acid, 2,2′-azobis (2,4,4-trimethylpentane), 1,1′-azobis (1-acetoxy-1 -Phenylethane) and the like.

  Among the above-mentioned azo polymerization initiators, from the viewpoint that the polymerization initiator is highly soluble in a solvent and easy to handle, the resulting hyperbranched polymer has a fragment of the polymerization initiator used for the polymerization at its terminal. Therefore, dimethyl 2,2′-azobisisobutyrate is preferred from the viewpoint that the solubility of the polymer can be controlled by chemical conversion of the ester group incorporated at the polymer terminal.

  The polymerization initiator B is used in an amount of 20 to 300 mol%, preferably 50 to 300 mol%, more preferably 50 to 200 mol%, based on the monomer A.

<Method for producing hyperbranched polymer>
The electrochromic material (hyperbranched polymer) of the present invention is obtained by polymerizing the above-mentioned monomer in the presence of a predetermined amount of polymerization initiator B. As the polymerization method, known methods such as solution polymerization and dispersion are used. Polymerization, precipitation polymerization, bulk polymerization and the like can be mentioned, among which solution polymerization or precipitation polymerization is preferable. In particular, it is preferable to carry out the reaction by solution polymerization in an organic solvent from the viewpoint of molecular weight control.
Examples of organic solvents used here include aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and tetralin; aliphatic or alicyclic hydrocarbon solvents such as n-hexane, n-heptane, mineral spirit, and cyclohexane Solvent: Halogen solvents such as methyl chloride, methyl bromide, methyl iodide, methylene dichloride, chloroform, carbon tetrachloride, trichloroethylene, perchloroethylene, orthodichlorobenzene; ethyl acetate, butyl acetate, methoxybutyl acetate, methyl cellosolve acetate , Ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, and other ester or ester ether solvents; diethyl ether, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cello Ether solvents such as rub, butyl cellosolve, propylene glycol monomethyl ether; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, di-n-butyl ketone, cyclohexanone; methanol, ethanol, n-propanol, isopropanol, n-butanol, iso Alcohol solvents such as butanol, tert-butanol, 2-ethylhexyl alcohol, benzyl alcohol, ethylene glycol; amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide; sulfoxide solvents such as dimethyl sulfoxide, N -Heterocyclic compound type | system | group solvents, such as methyl-2-pyrrolidone, and these 2 or more types of mixed solvents are mentioned.
Of these, preferred are aromatic hydrocarbon solvents, halogen solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, amide solvents, sulfoxide solvents, etc., and particularly preferred are toluene. Xylene, orthodichlorobenzene, butyl acetate, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, 1,4-dioxane, methyl cellosolve, N, N-dimethylformamide, N, N-dimethylacetamide and the like.

When the polymerization reaction is carried out in the presence of an organic solvent, the content of the organic solvent in the entire polymerization reaction product is preferably 1 to 100 parts by weight, more preferably 5 to 50 parts by weight with respect to 1 part by weight of the monomer A. is there.
The polymerization reaction is carried out under normal pressure, under pressure and under pressure, or under reduced pressure, and is preferably carried out under normal pressure in view of simplicity of the apparatus and operation. Further, preferably carried out in an atmosphere of inert gas such as N _2.
The temperature of the polymerization reaction is preferably 50 to 200 ° C., more preferably 70 to 150 ° C., and the polymerization time is preferably 1 to 24 hours, more preferably 3 to 10 hours.

  After completion of the polymerization reaction, the obtained hyperbranched polymer (electrochromic material) is collected by an arbitrary method, and post-treatment such as washing is performed as necessary. Examples of a method for recovering the hyperbranched polymer from the reaction solution include a method such as reprecipitation.

  The weight average molecular weight (hereinafter abbreviated as Mw) of the obtained hyperbranched polymer (electrochromic material) is 1,000 to 2,000,000, preferably 10,000 in terms of polyethylene glycol by gel permeation chromatography (GPC). To 1,000,000, or 1,000 to 200,000 in terms of polystyrene, preferably 5,000 to 100,000.

The polymer thus obtained is also an object of the present invention.
That is, in the present invention, the monomer A represented by the formula (6) having a portion exhibiting electrochromic properties is polymerized in the presence of 20 to 300 mol% of the polymerization initiator B with respect to the monomer A. The present invention also relates to a hyperbranched polymer obtained by the treatment. As described above, the hyperbranched polymer of the present invention is a so-called initiator fragment-incorporating hyperbranched polymer, and has a fragment of the polymerization initiator B used for polymerization at the terminal. For this reason, it is possible to easily adjust the physical properties (solvent solubility, etc.) of the obtained hyperbranched polymer.
Among them, the part E that exhibits electrochromic properties in the formula (6) is preferably a hyperbranched polymer having a structure represented by the formula (7), formula (8), formula (9), or formula (10). .

<Method for producing electrochromic element>
The electrochromic material of the present invention can be used as a material for an electrochromic device. The electrochromic element includes at least one transparent conductive substrate, an ion conductive material layer interposed between the substrates, and the ion conductive material layer and any one of the conductive substrates. It is composed of an electrochromic coloring layer inserted in The electrochromic coloring layer contains the electrochromic material of the present invention. A typical configuration example of such an electrochromic element is shown in FIG.

As shown in FIG. 1, as an example, the electrochromic element has an electrochromic (EC) layer 3 formed on the surface of a transparent conductive substrate having a transparent electrode layer 2 formed on one surface of the transparent substrate 1. The first laminate and the second laminate (transparent conductive substrate) in which the transparent electrode layer 5 is formed on one surface of the transparent substrate 6, the electrochromic layer 3 of the first laminate, and the second laminate The transparent electrode layers 5 of the laminated body are opposed to each other at an appropriate interval so as to face each other, and a charge transport (CT) layer 4 having an ion conductive material is sandwiched therebetween.
The element can cause an electrochromic phenomenon by applying a voltage between the electrodes, and can cause color development and decoloration. A well-known thing can be utilized as a voltage application means.

A method for forming each film and layer constituting the electrochromic element is not particularly limited, and it can be produced by a conventional method for forming a film and a layer.
For example, as shown in FIG. 2, a glass substrate with ITO is adopted as a transparent conductive substrate having a transparent electrode layer 2 formed on one surface of a transparent substrate 1, and an electrochromic material is formed on the substrate by a method exemplified below. EC (electrochromic) layer 3 containing is formed, and a first laminate (laminate A) is produced. In addition, this glass substrate with ITO is also said 2nd laminated body (laminate board B).

As the transparent substrate, a transparent resin or the like can be used in addition to a glass substrate, and it may be a hard plate or a flexible film. Examples of the resin used as the transparent substrate include transparent resins such as polyethylene terephthalate, polyester, polyethylene, polypropylene, nylon, polyvinyl chloride, polycarbonate, polyvinyl alcohol, polymethyl methacrylate, fluororesin, ethylene, and vinyl alcohol.
As the transparent electrode layer provided on the transparent substrate, in addition to the above-mentioned ITO (tin-added indium oxide), ATO (antimony-added tin oxide), FTO (fluorine-added tin oxide), AZO (aluminum-added zinc oxide), GZO ( Gallium-doped zinc oxide), noble metal thin films such as Au, Ag, and Pt can be used.

As a specific method for forming the EC layer, first, an electrochromic material is dissolved or dispersed in a solvent to form a varnish (film forming material), and the varnish is cast on a substrate, a spin coating method, Apply by blade coating method, dip coating method, roll coating method, bar coating method, die coating method, ink jet method, printing method (letter plate, intaglio plate, planographic plate, screen printing, etc.), then dry in a hot plate or oven, etc. To form a film. Among these coating methods, the spin coating method is preferable. In the case of using the spin coating method, since it can be applied in a single time, even a highly volatile solution can be used, and there is an advantage that highly uniform application can be performed.
Examples of the solvent used in the form of the varnish include N, N′-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), methanol, ethanol, propanol, water, tetrahydrofuran (THF), and trichloromethane. These solvents may be used alone, or two or more kinds of solvents may be mixed.
In addition, the concentration in which the solvent is dissolved or dispersed is arbitrary, but the concentration of the electrochromic material is 0.001 to 90% by mass with respect to the total mass (total mass) of the electrochromic material and the solvent, preferably 0. 0.002 to 80% by mass, more preferably 0.005 to 70% by mass.
The thickness of the formed EC layer is usually 0.01 μm to 50 μm, preferably 0.1 μm to 20 μm.
Further, if necessary, in addition to the electrochromic material of the present invention, a film or a layer may be formed using a compound further promoting color development.

Thereafter, the electrochromic layer 3 of the laminated plate A and the transparent electrode layer 5 of the laminated plate B are opposed to each other at an interval of about 1 to 1,000 μm, and the periphery excluding the injection port is sealed with a sealing material 7. An empty cell with a mark is produced. A liquid ion conductive material is injected from the injection port, and the injection port is appropriately sealed, thereby forming a CT (charge transport) layer 4 to complete the electrochromic device.
Alternatively, a liquid ion conductive material is dropped on the EC layer 3 of the laminate A (or the electrode layer 5 of the laminate B), and the electrode layer 5 (or laminate) of the laminate B is added to the dropped ion conductive material. The laminated plate B (or laminated plate A) is overlapped so that the EC layer 3) of A is in contact, and the periphery is sealed to complete the electrochromic device.

The ion conductive substance used for the CT layer 4 of the electrochromic element is preferably a substance that usually exhibits an ion conductivity of 1 × 10 ⁻⁷ S / cm or more at room temperature. The ion conductive material is not particularly limited, and examples thereof include a liquid ion conductive material, a gel ion conductive material, and a solid ion conductive material.
Among these, for example, as a liquid material, a solution in which a supporting electrolyte such as a salt, an acid, or an alkali is dissolved in a solvent can be used. The solvent is not particularly limited as long as it can dissolve the supporting electrolyte, but a solvent having polarity is particularly preferable. Specifically, water, methanol, ethanol, propylene carbonate, ethylene carbonate, dimethyl sulfoxide, dimethoxyethane, acetonitrile, cyclohexanone, γ-butyrolactone, γ-valerolactone, sulfolane, N, N-dimethylformamide, dimethoxyethane, tetrahydrofuran, Examples thereof include organic polar solvents such as propiononitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, N, N-dimethylacetamide, methylpyrrolidinone, dioxolane, trimethyl phosphate, and polyethylene glycol. These can be used alone or as a mixture in use.
The salt as the supporting electrolyte is not particularly limited, and examples thereof include inorganic ion salts such as various alkali metal salts and alkaline earth metal salts, quaternary ammonium salts, cyclic quaternary ammonium salts, and the like. _{4, LiSCN, LiBF 4, LiAsF} 6, LiCF 3 SO 3, LiPF 6, LiI, NaI, NaSCN, or _{NaClO 4, NaBF 4, NaAsF 6} , KSCN, alkali metal salts of KCl and the like, such as, (CH _{3) 4} NBF _{4, (C 2 H 5)} 4 NBF 4, (n-C 4 H 9) 4 NBF 4, (C 2 H 5) 4 NBr, (n-C 4 H 9) 4 NBr, (C 2 H 5) Preferred examples include quaternary ammonium salts such as ₄ NClO ₄ and (nC ₄ H ₉ ) ₄ NClO _4, cyclic quaternary ammonium salts, and the like, or mixtures thereof.

  In the electrochromic device, a spacer can be used to ensure a constant distance between the laminate A and the laminate B. Although it does not specifically limit as a spacer, The bead, fiber, or sheet | seat comprised with glass, a polymer, etc. can be used. The spacer can be inserted by a gap between the conductive substrates facing each other, or can be provided by a method of forming a projecting object made of an insulating material such as resin on the electrode of the conductive substrate.

The electrochromic element is not limited to the above-described configuration and manufacturing method, and may further include other structures or elements.
Other structures or elements include, for example, UV-cutting layers such as UV-reflecting layers and UV-absorbing layers, and in the case of applications for electrochromic mirrors, the entire mirror layer or an overcoat layer for the purpose of protecting the surface of each film layer Etc.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited to the following Example. In the examples, sample preparation and physical property measurement were performed using the following apparatus under the following conditions.
(1) Gel permeation chromatography polystyrene conversion Device: HLC-8220GPC manufactured by Tosoh Corporation
Column: Shodex KF-804L, KF-805L
Column temperature: 40 ° C
Solvent: Tetrahydrofuran Detector: RI
Polyethylene glycol equivalent Device: HLC-8220GPC manufactured by Tosoh Corporation
Column: TSK-GEL G6000PWXL-CP, G3000PWXL-CP
Column temperature: 40 ° C
Solvent: 20 mM sodium nitrate aqueous solution Detector: RI
(2) TEM observation apparatus: Hitachi Transmission Electron Microscope H-8000 manufactured by Hitachi High-Technologies Corporation
Accelerating voltage: 200kV
(3) Spin coater: K-359SD-2 SPINNER manufactured by Kyowa Riken Co., Ltd.
(4) Laser microscope apparatus: Keyence Co., Ltd. ultra deep shape measuring microscope VK-8510
(5) Digital micrometer device: manufactured by Mitutoyo Corporation ABS Digimatic Caliper 500-150
(6) Light source device: Xenon lamp E7536 manufactured by Hamamatsu Photonics Co., Ltd.
(7) Thermal cut filter device: IRA No. manufactured by AGC Techno Glass Co., Ltd. 2
(8) UV cut filter Device: Toshiba Glass Co., Ltd. (currently AGC Techno Glass Co., Ltd.) (9) Detector Device: OptoSirius Co., Ltd. Ocean Optics USB4000
(10) Current-voltage characteristics Apparatus: Electrochemical analyzer ALS708C manufactured by BAS Co., Ltd.

The main reagents used in the synthesis examples and examples are as follows.
Chloromethylstyrene: CMS-14 manufactured by AGC Seimi Chemical Co., Ltd.
4,4′-bipyridine: manufactured by Tokyo Chemical Industry Co., Ltd. Special grade terephthalic acid: produced by Tokyo Chemical Industry Co., Ltd. Special grade 4,4′-biphenylcarboxylic acid: produced by Aldrich Co., Ltd. 1,4-diacetylbenzene: Tokyo Chemical Industry Co., Ltd. First grade 4-vinylbenzoic acid: Wako Pure Chemical Industries, Ltd. 2,6-lutidine: Tokyo Chemical Industry Co., Ltd. First grade 6-bromohexanoyl chloride: Tokyo Chemical Industry Co., Ltd. 2,2 '-Azobisisobutyric acid dimethyl: Otsuka Chemical Co., Ltd. Propylene carbonate: Tokyo Chemical Industry Co., Ltd. Special grade lithium perchlorate: Kishida Chemical Co., Ltd. Special grade polymethyl methacrylate: Aldrich Mw = 350,000

[Synthesis Example 1] Synthesis of Monomer 1
Under a nitrogen atmosphere, 4.6 g (30 mmol) of chloromethylstyrene, 0.78 g (5 mmol) of 4,4′-bipyridine and 150 mL of N, N-dimethylformamide (hereinafter abbreviated as DMF) were added to the reactor, and the mixture was heated at 60 ° C. Stir for 20 hours. After completion of the reaction, the reaction mixture was filtered, and the filtrate was washed with acetone. The obtained wet product was dried to obtain 1.2 g of monomer 1 as a yellow solid (yield 50%).

Example 1 Synthesis of Hyperbranched Polymer 1 1.15 g (2.5 mmol) of monomer 1 obtained in Synthesis Example 1 and 1.15 g (5 mmol) of dimethyl 2,2′-azobisisobutyrate in a reactor in a nitrogen atmosphere. And 44 g of ethylene glycol was added and stirred at 100 ° C. for 6 hours. After completion of the reaction, the reaction mixture was concentrated. The residue was dissolved in 5 mL of methanol, and 400 mL of ethyl acetate was added for reprecipitation. The precipitated solid was filtered and dried to obtain 1.5 g of hyperbranched polymer 1 as a light pink solid (yield: 65%).
The obtained hyperbranched polymer 1 had a weight average molecular weight (Mw) in terms of polyethylene glycol of 1,300,000.

Test Example 1 TEM (Transmission Electron Microscope) Observation of Hyperbranched Polymer 1 A 0.01% by mass methanol solution of hyperbranched polymer 1 obtained in Example 1 was dropped on a carbon mesh grid, dried, and TEM. An observation sample was prepared. When this sample was observed by TEM, spherical particles having a particle size of about 10 nm were observed. The observed TEM image is shown in FIG.
Usually, a linear polymer cannot be observed as a TEM image even if a sample is prepared under the same conditions and observed by TEM, and only a highly branched polymer can be observed by TEM. It was suggested that it was highly branched.

[Synthesis Example 2] Synthesis of Monomer 2
Under a nitrogen atmosphere, 1.0 g (6 mmol) of terephthalic acid, 0.67 g (12 mmol) of potassium hydroxide and 20 mL of methanol were added to the reactor, and the mixture was stirred at room temperature for 1 hour. After completion of the reaction, the reaction mixture was concentrated to dryness. Thereto were added 2.7 g (18 mmol) of chloromethylstyrene and 25 mL of DMF, and the mixture was stirred at 100 ° C. for 8 hours. After completion of the reaction, the reaction mixture was filtered to remove the precipitate, and the filtrate was concentrated. The residue was washed with hexane and recrystallized with ethyl acetate to obtain 0.66 g of white solid monomer 2 (yield 28%).

[Example 2] Synthesis of hyperbranched polymer 2 In a nitrogen atmosphere, 0.40 g (1 mmol) of monomer 2 obtained in Synthesis Example 2 in a reactor, 0.46 g (2 mmol) of dimethyl 2,2'-azobisisobutyrate and toluene 16g was added and it stirred at 100 degreeC for 5 hours. After completion of the reaction, the reaction mixture was concentrated. The residue was dissolved in a small amount of chloroform and re-precipitated by adding diisopropyl ether. After the precipitated solid was filtered, a reprecipitation operation was performed again in the same manner. The precipitated solid was filtered and dried to obtain 0.30 g of hyperbranched polymer 2 as a white solid (yield 35%).
The resulting hyperbranched polymer 2 had a weight average molecular weight (Mw) in terms of polystyrene of 8,800.

[Synthesis Example 3] Synthesis of Monomer 3
Under a nitrogen atmosphere, 1.5 g (6 mmol) of biphenyl-4,4′-dicarboxylic acid, 0.67 g (12 mmol) of potassium hydroxide and 20 mL of methanol were added to the reactor, and the mixture was stirred at room temperature for 4 hours. After completion of the reaction, the reaction mixture was concentrated to dryness. Chloromethylstyrene 5.6g (36mmol) and DMF25mL were added there, and it stirred at 100 degreeC for 8 hours. After completion of the reaction, the reaction mixture was filtered to remove the precipitate, and the filtrate was concentrated. The residue was recrystallized with ethyl acetate to obtain 0.66 g of monomer 3 as a white solid (yield 32%).

[Example 3] Synthesis of hyperbranched polymer 3 In a nitrogen atmosphere, 0.48 g (1 mmol) of monomer 3 obtained in Synthesis Example 3 in a reactor, 0.46 mg (2 mmol) of dimethyl 2,2′-azobisisobutyrate and toluene 20g was added and it stirred at 100 degreeC for 5 hours. After completion of the reaction, the reaction mixture was concentrated. The residue was dissolved in a small amount of chloroform and re-precipitated by adding diisopropyl ether. After the precipitated solid was filtered, a reprecipitation operation was performed again in the same manner. The precipitated solid was filtered and dried to obtain 0.28 g of hyperbranched polymer 3 as a white solid (yield 30%).
The resulting hyperbranched polymer 3 had a weight average molecular weight (Mw) in terms of polystyrene of 8,100.

[Synthesis Example 4] Synthesis of Monomer 4
In a mixed solution of 80 mL of acetic acid and 5 mL of 48% aqueous hydrogen bromide solution, 3.2 g (20 mmol) of 1,4-diacetylbenzene was added and cooled to 0 ° C. To this mixed solution, 6.4 g (40 mmol) of bromine was slowly added so that the reaction temperature did not exceed 20 ° C. Thereafter, the mixture was stirred at 0 ° C. for 30 minutes and at room temperature for 1 hour. After completion of the reaction, the reaction mixture was filtered, and the residue was washed with an ethanol-water mixed solution (volume ratio 1: 1). The obtained wet product was dried to obtain 5.5 g of white solid 1,4-bis (2-bromoacetyl) benzene (yield 86%).
Under a nitrogen atmosphere, 4.2 g (13 mmol) of 1,4-bis (2-bromoacetyl) benzene obtained, 3.9 g (26 mmol) of 4-vinylbenzoic acid, and 70 mL of tetrahydrofuran (hereinafter abbreviated as THF) were added. To the reactor, 5 mL (36 mmol) of triethylamine was added dropwise and stirred at room temperature for 16 hours. After completion of the reaction, the reaction mixture was filtered, and the filtrate was washed with water and ethyl acetate. The obtained wet product was dried to obtain 4.8 g of monomer 4 as a white solid (yield 81%).

Example 4 Synthesis of Hyperbranched Polymer 4 In a nitrogen atmosphere, 0.45 g (1 mmol) of monomer 4 obtained in Synthesis Example 4 in a reactor, 0.46 g (2 mmol) of dimethyl 2,2′-azobisisobutyrate and 17 g of DMF And stirred at 100 ° C. for 5 hours. After completion of the reaction, the reaction mixture was concentrated. The residue was dissolved in a small amount of THF and re-precipitated by adding diisopropyl ether. After the precipitated solid was filtered, a reprecipitation operation was performed again in the same manner. The precipitated solid was filtered and dried to obtain 0.53 g of a hyperbranched polymer 4 as a white solid (yield 60%).
The resulting hyperbranched polymer 4 had a weight average molecular weight (Mw) in terms of polystyrene of 20,000.

[Synthesis Example 5] Synthesis of Monomer 5
To the reactor were added 54 g (350 mmol) of chloromethylstyrene, 40 g (420 mmol) of potassium acetate and 150 mL of dimethyl sulfoxide (hereinafter abbreviated as DMSO), and the mixture was stirred at 40 ° C. for 48 hours. After completion of the reaction, the reaction mixture was added to 150 mL of water and extracted with ethyl acetate. The separated ethyl acetate layer was dried over anhydrous magnesium sulfate and concentrated. The residue was added to a solution in which 25 g (625 mmol) of sodium hydroxide was dissolved in 150 mL of an ethanol-water mixed solution (volume ratio 5: 1) and refluxed for 1.5 hours. Thereafter, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The separated ethyl acetate layer was dried over anhydrous magnesium sulfate and concentrated. The residue was purified by column chromatography (chloroform) to obtain 47 g of 4-hydroxymethylstyrene (yield 98%).
Under a nitrogen atmosphere, 2.7 g (20 mmol) of hydroxymethylstyrene obtained in the reactor, 2.7 mL (22 mmol) of 2,6-lutidine and 30 mL of THF were added, and the mixture was cooled to 0 ° C. with stirring. To this mixed solution, 3.2 mL (21 mmol) of bromohexanoyl chloride was dropped with a syringe over about 10 minutes. After completion of the reaction, the reaction mixture was filtered to remove the precipitate, and the filtrate was concentrated. The residue was purified by column chromatography (chloroform) to quantitatively obtain 4-vinylbenzyl 6-bromohexanoate.
Under a nitrogen atmosphere, 3.1 g (10 mmol) of 4-vinylbenzyl 6-bromohexanoate obtained in the reactor, 0.55 g (3.5 mmol) of 4,4′-bipyridine and 35 mL of DMF were added, and the mixture was stirred at 60 ° C. for 24 hours. Stir. After completion of the reaction, the reaction mixture was concentrated. Toluene was added to the residue, and insoluble matters were filtered. This filtrate was dissolved in a small amount of chloroform, and ethyl acetate was added to reprecipitate the precipitated solid, which was filtered and dried to obtain 1.7 g of monomer 5 (yield 31%).

Example 5 Synthesis of Hyperbranched Polymer 5 0.39 g (0.5 mmol) of monomer 5 obtained in Synthesis Example 5 and 0.23 g (1 mmol) of dimethyl 2,2′-azobisisobutyrate in a reactor in a nitrogen atmosphere. And 12 g of ethylene glycol was added and stirred at 100 ° C. for 6 hours. After completion of the reaction, the reaction mixture was concentrated. The residue was dissolved in a small amount of methanol, and a THF-hexane mixed solution (volume ratio 1: 1) was added to cause reprecipitation. After the precipitated solid was filtered, a reprecipitation operation was performed again in the same manner. The precipitated solid was filtered and dried to obtain 0.24 g of a hyperbranched polymer 5 as a yellow solid (yield 38%).
Since the obtained hyperbranched polymer 5 was hardly soluble in both THF and 20 mM sodium nitrate, the weight average molecular weight could not be measured by GPC.

[Example 6] Electrochromic evaluation (color development with voltage application)
Using the hyperbranched polymers 1 to 5 obtained in Examples 1 to 5, an electrochromic cell according to the configuration shown in FIG. 1 was prepared and evaluated by the following method.
<Cleaning of ITO glass substrate>
The dust on the surface of the ITO glass substrate (26 mm × 22 mm) was blown off with an air duster, and the ITO glass substrate was washed with boiling ethanol.
<Preparation of electrochromic (EC) layer>
Hyperbranched polymers 1 to 5 were dissolved in the solvents shown in Table 1 to prepare 5 mass% solutions. Each solution obtained was applied to the ITO surface of the ITO glass substrate by spin coating (2,000 rpm, 1 minute), and then dried on a 40 ° C. hot plate for 1 day to form a film.
A part of the obtained film was scratched with a razor and observed with a laser microscope, and the film thickness was determined from the difference in focal length between the scratched part and the film part. The EC layer using any hyperbranched polymer had a thickness of about 200 nm.
<Preparation of charge transport (CT) layer>
In 10 mL of propylene carbonate, 0.5 g of lithium perchlorate was dissolved, and 10 g of polymethyl methacrylate and 30 mL of acetonitrile were added to this mixture. The mixture was stirred for 24 hours while heating at 110 ° C. to prepare a lithium electrolyte solution.
The obtained lithium electrolyte solution was uniformly cast on an ITO glass substrate and dried on a hot plate at 40 ° C. for 1 hour.
<Production of EC cell>
The above-mentioned lithium electrolyte solution was dropped on the EC layer produced on the ITO glass substrate, and an ITO glass substrate on which a CT layer was arranged so that the glass substrate side was on the outer side was placed thereon. As a result, the lithium electrolyte solution spread across the entire surface between the two glass substrates, and a uniform film was formed. This was dried on a hot plate at 40 ° C. for 1 day to produce an EC cell.
When the thickness of the CT layer of the obtained EC cell was measured with a digital micrometer, the EC layer using any hyperbranched polymer had a CT layer thickness of about 15 μm.
<Evaluation of drive voltage and color development>
A negative voltage was gradually applied to the produced EC cell, and the colored voltage and its color were evaluated. The results are shown in Table 1.

  As shown in Table 1, when the highly branched polymer 1 was used, a magenta color was developed with a particularly low driving voltage.

[Example 7] Electrochromic evaluation (discoloration with positive / negative voltage application)
A change in absorbance at a wavelength of 530 nm when a positive / negative voltage of 2 V was alternately applied to the EC cell using the highly branched polymer 1 produced in Example 6 was measured. A xenon lamp was used as the light source, and the light passing through the heat cut filter and the UV cut filter was measured with a detector.
It was confirmed that the EC cell that developed a color of magenta at −2V disappeared when a reverse voltage of + 2V was applied, and reversibly disappeared. Further, it was confirmed that when the applied voltage was raised to -2.5 V, the contrast was increased and the color was more clearly erased. The results are shown in FIG.

[Example 8] Production of flexible electrochromic device <Production of patterned ITO substrate>
A positive resist (Tokyo Ohka Kogyo Co., Ltd., TMSR-8900) is applied to the ITO electrode surface of a polycarbonate ITO substrate (Teijin Limited, 76 mm × 70 mm) by spin coating (300 rpm × 3 seconds, then 4, 000 rpm × 30 seconds) and dried by heating on a 40 ° C. hot plate for 5 minutes. The obtained resist film was subjected to mask exposure and then developed with a developer (manufactured by Tokyo Ohka Kogyo Co., Ltd., NMD-3). Next, this substrate was immersed in an ITO etching solution (manufactured by Kanto Chemical Co., Ltd., ITO-07N) for 5 minutes to remove ITO in the pattern exposure portion. Finally, the resist film remaining on the substrate was removed with acetone, washed with ion-exchanged water, and dried to prepare a patterned ITO substrate.
<Preparation of electrochromic (EC) layer>
The hyperbranched polymer 1 obtained in Example 1 was dissolved in methanol to prepare a 2% by mass solution. The obtained solution was applied to the ITO electrode surface of the patterned ITO substrate by spin coating (100 rpm × 10 seconds, then 2,000 rpm × 60 seconds). This coating film was dried on a hot plate at 40 ° C. for 24 hours to obtain an EC layer.
<Preparation of charge transport (CT) layer>
2.0 g of lithium perchlorate was dissolved in 10 mL of propylene carbonate, and 10 g of polymethyl methacrylate and 30 mL of acetonitrile were added to this mixture. The mixture was stirred for 24 hours while heating at 110 ° C. to prepare a lithium electrolyte solution to be a CT layer.
The obtained lithium electrolyte solution was cast uniformly on the ITO electrode surface of another polycarbonate ITO substrate (76 mm × 70 mm) and dried on a hot plate at 40 ° C. for 1 hour.
<Production of flexible EC element>
The above-mentioned lithium electrolyte solution was cast on the EC layer produced on the patterned ITO substrate, and the ITO substrate on which the CT layer was further placed was placed thereon so that the CT layer was inside. As a result, the CT layer solution spread across the entire surface between the two ITO substrates, and a uniform CT layer was obtained. This was dried on a hot plate at 40 ° C. for 24 hours to produce a flexible EC element.
When a voltage of −3 V was applied to the obtained EC element, the produced pattern was colored and displayed in magenta. Moreover, the pattern display was maintained even when the voltage application was stopped. Further, as shown in FIG. 5, this EC element is a flexible EC element having flexibility, and its thickness (ITO substrate + EC layer + CT layer + ITO substrate) was 0.4 mm.

[Example 9] Production of electrochromic devices (EC cells) A, B and C <Cleaning of ITO glass substrate>
The dust on the surface of the ITO glass substrate (10 mm × 20 mm) was blown off with an air duster, and the ITO glass substrate was washed with boiling ethanol.
<Preparation of electrochromic (EC) layer>
Hyperbranched polymer 1 was dissolved in methanol to prepare methanol solutions having the concentrations shown in Table 2, respectively. Each of the obtained solutions was applied to the ITO surface of the ITO glass substrate by the spin coating method under the conditions shown in Table 2, and then dried on a 40 ° C. hot plate for 1 day to form a film.
A part of the obtained film was scratched with a razor and observed with a laser microscope, and the film thickness was determined from the difference in focal length between the scratched part and the film part. The results are shown in Table 2.
<Preparation of charge transport (CT) layer>
Lithium perchlorate (2.0 g) was dissolved in propylene carbonate (40 mL), and polymethyl methacrylate (10 g) and acetonitrile (80 mL) were added to the mixture. The mixture was stirred for 6 hours while heating at 90 ° C. to prepare a lithium electrolyte solution.
The obtained lithium electrolyte solution was cast uniformly on an ITO glass substrate.
<Production of EC cell>
The above-mentioned lithium electrolyte solution was dropped on the EC layer produced on the ITO glass substrate, and an ITO glass substrate on which a CT layer was arranged so that the glass substrate side was on the outer side was placed thereon. As a result, the lithium electrolyte solution spread across the entire surface between the two glass substrates, and a uniform film was formed. This was dried on a hot plate at 40 ° C. for 1 day to produce an EC cell.
When the film thickness of the CT layer of the obtained EC cell was measured with a digital micrometer, the CT layer thickness of any EC cell was approximately 15 μm.

Example 10 Dependence of Current-Voltage Characteristics on EC Layer Thickness Current-voltage characteristics of EC cell A (EC layer thickness 150 nm) and EC cell C (EC layer thickness 300 nm) fabricated in Example 9 were measured. In the present specification, positive voltage application means that the electrode on the EC layer side is the positive electrode, and negative voltage application means that the electrode on the CT layer side is the positive electrode.
In any EC cell, a current started to flow from around −2 V, and a magenta color was developed. It was also confirmed that the thicker the EC layer, the greater the current value and the greater the contrast. The results are shown in FIG.

[Example 11] Dependence of transmittance on EC layer film thickness A voltage of -2.8 V was applied to EC cell A (EC layer thickness 150 nm) and EC cell C (EC layer thickness 300 nm) fabricated in Example 9, The transmittance of each EC cell that developed a magenta color was measured. In addition, the transmittance | permeability at the time of decoloring of each EC cell was 100%.
Each EC cell showed an absorption peak around 550 nm. In addition, it was confirmed that the thicker the EC layer, the lower the transmittance, that is, the color development is deeper. The obtained spectrum is shown in FIG.

[Example 12] Dependence of absorbance on applied voltage The absorbance of the EC cell was measured when voltages of -2.5 V, -2.0 V, and 0 V were applied to the EC cell B prepared in Example 9, respectively. The absorbance was measured in the same manner as in Example 7.
The absorbance of the EC cell was dependent on the applied voltage, and it was confirmed that coloring with a higher color by applying a higher negative voltage. The obtained spectrum is shown in FIG.

[Example 13] Dependence of color development response speed on applied voltage The EC cell C produced in Example 9 was subjected to -2.8V, -2.4V, and -2.0V, respectively. The time change of absorbance at a wavelength of 550 nm was measured. The absorbance was measured in the same manner as in Example 7.
The change in absorbance of the EC cell was dependent on the applied voltage, and it was confirmed that color development was faster, that is, the color development response speed was faster by applying a higher negative voltage. The obtained spectrum is shown in FIG.

[Example 14] Color fading accompanying application of positive and negative voltages The EC cell C produced in Example 9 was measured for changes in absorbance at a wavelength of 550 nm when a positive and negative voltage of 2.5 V was applied. The absorbance was measured in the same manner as in Example 7.
It was confirmed that EC cells that developed a magenta color at −2.5 V were colored as they were even when the voltage application was stopped, and exhibited a memory property. In addition, it was confirmed that the color disappears when the voltage of +2.5 V is applied, and the color disappears reversibly.

DESCRIPTION OF SYMBOLS 1 ... Transparent substrate 2 ... Transparent electrode layer 3 ... Electrochromic layer 4 ... Charge transport layer 5 ... Transparent electrode layer 6 ... Transparent substrate 7 ... Sealing material A ... Laminate A (first laminate)
B ... Laminated board B (second laminated body)

Claims (20)

A monomer A having a portion exhibiting electrochromic properties and two or more radical polymerizable double bonds in the same molecule is polymerized in the presence of 20 to 300 mol% of a polymerization initiator B with respect to the monomer A. An electrochromic material consisting of a hyperbranched polymer obtained by processing. 2. The electrochromic according to claim 1, wherein the monomer A having an electrochromic property in the same molecule and two or more radical polymerizable double bonds is a compound represented by the following formula (1). material.
[Wherein, R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and A ¹ and A ² each independently represent an alkyl group having 1 to 1 carbon atoms which may contain an ether bond or an ester bond. 14 represents a divalent hydrocarbon residue, and E represents a portion that exhibits electrochromic properties. ] The electrochromic material according to claim 2, wherein A ¹ and A ^{2 in the} formula (1) have a structure represented by any one of the following formulas (2) to (5).
[Wherein, p, q, r and s are repeating numbers, each independently represents an integer of 1 to 6, and * is a side linked to E which is a portion that develops electrochromic properties. ] The electrochromic material according to claim 2, wherein the monomer A represented by the formula (1) is a compound represented by the following formula (6).
[In formula, E represents the same meaning as said Formula (1). ] The part E expressing the electrochromic property in the formula (6) is a part of a quaternary bipyridinium salt structure, a part of a 1,4-diacetylbenzene structure, a part of a terephthalic acid diester structure, or biphenyl-4,4′-dicarboxylic The electrochromic material according to claim 4, which is a part of an acid diester structure. The electrochromic material according to claim 5, wherein the portion E expressing the electrochromic property in the formula (6) has a structure represented by the following formula (7).
[Wherein R ^{3 to} R ¹⁰ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. And X ⁻ and Y ⁻ are each independently Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CH ₃ COO ⁻ , PhSO ₃ ⁻ , p-TolSO ₃ ⁻ or R. ²⁷ represents SO ₄ ^— (wherein Ph represents a phenyl group, p-Tol represents a para-tolyl group, and R ²⁷ represents a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms. Represents a group). ] The electrochromic material according to claim 5, wherein the portion E expressing the electrochromic property in the formula (6) is represented by the following formula (8).
[Wherein R ^{11 to} R ¹⁴ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ] The electrochromic material according to claim 5, wherein the portion E that expresses the electrochromic property in the formula (6) is represented by the following formula (9).
[Wherein, R ^{15 to} R ¹⁸ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ] The electrochromic material according to claim 5, wherein the portion E that exhibits electrochromic properties in the formula (6) is represented by the following formula (10).
[Wherein, R ^{19 to} R ²⁶ each independently represents a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ] The electrochromic material according to any one of claims 1 to 9, wherein the polymerization initiator B is an azo polymerization initiator. The electrochromic material according to claim 10, wherein the polymerization initiator B is dimethyl 2,2'-azobisisobutyrate. The weight average molecular weight (Mw) measured by gel permeation chromatography of the hyperbranched polymer is 1,000 to 2,000,000 in terms of polyethylene glycol, or 1,000 to 200,000 in terms of polystyrene. The electrochromic material according to any one of claims 1 to 11. It is obtained by polymerizing the monomer A represented by the following formula (6) having a portion exhibiting electrochromic properties in the presence of a polymerization initiator B in an amount of 20 to 300 mol% with respect to the monomer A. Hyperbranched polymer.
[In formula, E represents the part which expresses an electrochromic characteristic. ] The hyperbranched polymer of Claim 13 whose part E which expresses the electrochromic characteristic in the said Formula (6) is a structure represented by following formula (7).
[Wherein R ^{3 to} R ¹⁰ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. And X ⁻ and Y ⁻ are each independently Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CH ₃ COO ⁻ , PhSO ₃ ⁻ , p-TolSO ₃ ⁻ or R. ²⁷ represents SO ₄ ^— (wherein Ph represents a phenyl group, p-Tol represents a para-tolyl group, and R ²⁷ represents a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms. Represents a group). ] The hyperbranched polymer of Claim 13 whose part E which expresses the electrochromic characteristic in said Formula (6) is a structure represented by following formula (8).
[Wherein R ^{11 to} R ¹⁴ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ] The hyperbranched polymer of Claim 13 whose part E which expresses the electrochromic characteristic in said Formula (6) is a structure represented by following formula (9).
[Wherein, R ^{15 to} R ¹⁸ each independently represents a hydrogen atom, or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ] The hyperbranched polymer of Claim 13 whose part E which expresses the electrochromic characteristic in said Formula (6) is a structure represented by following formula (10).
[Wherein, R ^{19 to} R ²⁶ each independently represents a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms which may contain an ether bond or an ester bond. Represent. ] A varnish, wherein the electrochromic material according to any one of claims 1 to 12 is dissolved or dispersed in at least one solvent. A thin film structure containing the electrochromic material according to any one of claims 1 to 12. An electrochromic element in which a thin film-like structure containing the electrochromic material according to any one of claims 1 to 12 is sandwiched between two electrode layers, at least one of which is transparent.