WO2019159717A1

WO2019159717A1 - Light control member

Info

Publication number: WO2019159717A1
Application number: PCT/JP2019/003588
Authority: WO
Inventors: 青木　純; 暉伊藤; 茂樹渡邉; 慎貴酒向
Original assignee: 国立大学法人名古屋工業大学; トヨタ紡織株式会社
Priority date: 2018-02-19
Filing date: 2019-02-01
Publication date: 2019-08-22
Also published as: JP7072796B2; JP2019144330A; CN111670407A; CN111670407B

Abstract

Provided is a novel light control member (1). This light control member (1) is provided with a light control pole (3), a counter pole (5) and an electrolyte (7). The electrolyte (7) contains an ionic liquid, an organic solvent, silver ions and citric acid. For example, tin-doped indium oxide (ITO) is used as the light control pole (3). An ionic liquid which contains imidazolium cations is suitable for use as the ionic liquid of the present invention. This light control member has a configuration wherein the reflectance of visible light is changed by reversibly performing formation of a silver coating film by means of electrolytic plating and dissolution of the silver coating film by means of electrolytic dissolution.

Description

Light control member

The present disclosure relates to a light control member.

Conventionally, for example, the following are known as light control members. That is, it is electrochromic light control glass (resin glass) (see Patent Document 1). In the light control glass (resin glass), a material having a light control function and / or a transparent conductor is attached to each side surface of two glass (resin glass) plates. And the adhesion surface of a glass (resin glass) board is faced inside, the electrolyte for light control is distribute | arranged between them, and it light-controls by supplying with electricity.

JP 2003-344878 A

By the way, in recent years, product development using a light control member has been extensively performed, and there are cases where a desired effect cannot be obtained with an existing light control member. Therefore, development of a light control member having a novel configuration is eagerly desired.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a novel light control member. The present invention can be realized as the following forms.

[1] A light control member,
A dimming pole,
The opposite pole,
An electrolyte sandwiched between the dimming electrode and the counter electrode,
The light control member, wherein the electrolyte contains an ionic liquid, an organic solvent, silver ions, and citric acid.

[2] The configuration according to [1], wherein the reflectance of visible light is changed by reversibly performing formation of a silver coating by electrolytic plating and elution of the silver coating by electrolytic elution. Dimmable member.

[3] The light control member according to [2], wherein the silver coating has a mirror surface.

[4] The light control member according to any one of [1] to [3], wherein the cation portion of the ionic liquid is represented by the following general formula (1).

[In formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ are each independently
Hydrogen atom,
A substituted or unsubstituted C1-C20 saturated or unsaturated linear, branched, or cyclic alkyl group,
A substituted or unsubstituted aryl group having 6 to 30 carbon atoms,
A substituted or unsubstituted arylalkyl group having 7 to 31 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms,
When the alkyl group, the aryl group or the arylalkyl group is substituted, a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acyl group, an alkylsulfanyl group, Arylsulfanyl, alkylamino, dialkylamino, arylamino, hydroxy, carboxy, formyl, mercapto, sulfo, mesyl, p-toluenesulfonyl, amino, nitro, cyano, tri Substituted with a fluoromethyl group, a trichloromethyl group, a trimethylsilyl group, a phosphinico group, or a phosphono group. ]

[5] The light control member according to any one of [1] to [4], wherein the organic solvent is a polar solvent.

[6] The light control member according to any one of [1] to [5], wherein a volume ratio of the ionic liquid to the organic solvent is 90:10 to 10:90.

[7] The light control member according to any one of [1] to [6], which is used as a light control smart window, a light control mirror, or a design part.

Since the light control member of the present invention is a novel light control member using an electrolyte containing an ionic liquid, an organic solvent, silver ions, and citric acid, the application range of the light control member is expanded.
In a configuration in which the reflectance of visible light is changed by reversibly performing the formation of a silver coating by electrolytic plating and the elution of the silver coating by electrolytic elution, it can be effectively used as a mirror.
When the silver coating has a mirror surface, the reflectance of visible light is improved. In the present specification, visible light means light having a wavelength of 400 to 800 nm.
When an ionic liquid having a specific cation is used, formation of a silver film by electrolytic plating and elution of the silver film by electrolytic elution can be performed smoothly.
When the organic solvent is a polar solvent, citric acid is well dissolved in the electrolyte, and the formation of a silver coating by electrolytic plating and the elution of the silver coating by electrolytic elution can be performed smoothly.
When the volume ratio of the ionic liquid to the organic solvent is 90:10 to 10:90, formation of the silver coating by electrolytic plating and elution of the silver coating by electrolytic elution can be performed smoothly.
The light control member of the present invention is practically very effective when used as a light control smart window, a light control mirror, or a design part.

The invention will be further described in the following detailed description, given by way of non-limiting example of exemplary embodiments according to the invention, with reference to the mentioned drawings.
It is sectional drawing which shows the structure of a light control member typically. It is sectional drawing which shows an experimental apparatus typically. It is sectional drawing which shows a light control pole typically.

The items shown here are for illustrative purposes and exemplary embodiments of the present invention, and are the most effective and easy-to-understand explanations of the principles and conceptual features of the present invention. It is stated for the purpose of providing what seems to be. In this respect, it is not intended to illustrate the structural details of the present invention beyond what is necessary for a fundamental understanding of the present invention. It will be clear to those skilled in the art how it is actually implemented.

Hereinafter, the present invention will be described in detail. In the present specification, the description using “˜” in the numerical range includes the lower limit value and the upper limit value unless otherwise specified. For example, the description “10 to 20” includes both the lower limit “10” and the upper limit “20”. That is, “10 to 20” has the same meaning as “10 to 20”.

1. Light Control Member The light control member 1 of the present invention includes a light control electrode 3, a counter electrode 5, and an electrolyte 7, as shown in FIG. In addition, the code | symbol 9 means the sealing material which is arbitrary structural requirements.

(1) Dimming Electrode As the dimming electrode 3, a known transparent electrode used as a dimming electrode can be appropriately used. As the transparent electrode, for example, a transparent conductive film containing tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), or the like can be suitably used. Inorganic glass and resin glass such as polycarbonate (PC), polyethylene terephthalate (PET), and acrylic resin can be suitably used for the substrate of the transparent conductive film.
Pd nanoparticles may be attached to the surface of the transparent electrode. When a transparent electrode to which Pd nanoparticles are attached is used, the silver coating formed on the transparent electrode tends to exhibit a beautiful specular gloss. That is, the visible light reflectance of the silver coating formed on the transparent electrode tends to increase.
The method for attaching the Pd nanoparticles to the transparent electrode surface is not particularly limited. As a deposition method, a method in which Pd ²⁺ is strike-plated to deposit Pd nanoparticles is preferably employed.
The size of the Pd nanoparticle is not particularly limited. The average particle diameter of the Pd nanoparticle is preferably 5 to 70 nm, more preferably 10 to 60 nm, and particularly preferably 30 to 50 nm. When the average particle size is within this range, the dispersibility of the Pd nanoparticle on the transparent electrode is increased, and a silver coating with extremely high uniformity is formed by electrolytic plating.
The average particle diameter of the Pd nanoparticle is obtained by measuring the particle diameter of any 200 or more Pd nanoparticles using a scanning electron microscope (SEM) and averaging the measured values.
Moreover, the average Pd surface density in the case of carrying Pd is not particularly limited. The average Pd surface density is preferably 1.0 × 10 ⁻⁶ to 9.0 × 10 ⁻⁶ g / cm ² , more preferably 2.0 × 10 ⁻⁶ to 8.0 × 10 ⁻⁶ g / cm ^2. cm ² , more preferably 3.0 × 10 ⁻⁶ to 7.0 × 10 ⁻⁶ g / cm ² . Within this range, a sufficient transmittance for visible light can be secured for the dimming electrode before the silver coating is formed.

(2) Counter electrode As the counter electrode 5, a known electrode used as a counter electrode can be used as appropriate. As the counter electrode, for example, an Ag electrode, an ITO electrode, an FTO electrode, or the like can be suitably employed.

(3) Reference electrode The light control member may be equipped with the reference electrode. As the reference electrode, for example, an Ag / Ag ⁺ electrode, an Ag / AgCl electrode, an SCE electrode, or the like can be suitably used.

(4) Electrolyte The electrolyte 7 contains an ionic liquid, an organic solvent, silver ions, and citric acid. This “electrolyte” is sometimes referred to as an “Ag plating bath”.
Here, the background of the present invention will be described.
The conventional Ag plating bath uses highly toxic cyan as a ligand. Further, the conventional Ag plating bath is an aqueous solution-based plating bath, and when used for a light control member (device), there are problems of solvent volatilization and electrolyte salt precipitation. In addition, there is currently no Ag plating bath capable of reversibly performing electrolytic plating and electrolytic elution.
Under such circumstances, the electrolyte of the present invention was developed. The electrolyte of the present invention uses safe citric acid instead of cyanide. In addition, the electrolyte of the present invention uses a mixed system of an ionic liquid and an organic solvent instead of an aqueous system. The present inventors have found an unexpected fact that electrolytic plating and electrolytic elution can be performed reversibly by using an electrolyte containing an ionic liquid, an organic solvent, silver ions, and citric acid. The present invention has been made based on the above.
Next, each component will be described in detail.

(4.1) Ionic liquid The above-mentioned ionic liquid is in a molten state at room temperature (25 ° C.) and indicates an ionic substance composed of a cation part and an anion part.
As the cation portion of the ionic liquid, a cation used in a normal ionic liquid can be used. Examples thereof include a cation moiety selected from the group consisting of an onium cation, a quaternary ammonium cation, and a quaternary phosphonium cation of a 5- to 6-membered ring compound having 1 to 3 nitrogen atoms.

Examples of the onium cation of the 5- to 6-membered ring compound having 1 to 3 nitrogen atoms include, for example, an onium cation of a 5-membered ring compound such as an imidazolium cation and a pyrrolidinium cation, a pyridinium cation, and a piperidinium cation. Mention may be made of onium cations of member ring compounds. Among these, an imidazolium cation is preferable because it has a low melting point and easily becomes liquid.

The imidazolium cation is not particularly limited. For example, what has the structure of following General formula (1) can be mention | raise | lifted.

Substituted or unsubstituted C1-C20 saturated or unsaturated linear or branched, used as R ¹ , R ² , R ³ , R ⁴ , R ^{5 in the} chemical formula (1) Examples of the cyclic alkyl group include, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, Isoamyl group, tert-pentyl group, neopentyl group, n-hexyl group, 3-methylpentan-2-yl group, 3-methylpentan-3-yl group, 4-methylpentyl group, 4-methylpentane-2- Yl group, 1,3-dimethylbutyl group, 3,3-dimethylbutyl group, 3,3-dimethylbutan-2-yl group, n-heptyl group, 1-methylhexyl group, 3-methylhexyl group 4-methylhexyl group, 5-methylhexyl group, 1-ethylpentyl group, 1- (n-propyl) butyl group, 1,1-dimethylpentyl group, 1,4-dimethylpentyl group, 1,1-diethylpropyl Group, 1,3,3-trimethylbutyl group, 1-ethyl-2,2-dimethylpropyl group, n-octyl group, 2-methylhexane-2-yl group, 2,4-dimethylpentan-3-yl group 1,1-dimethylpentan-1-yl group, 2,2-dimethylhexane-3-yl group, 2,3-dimethylhexane-2-yl group, 2,5-dimethylhexane-2-yl group, , 5-dimethylhexane-3-yl group, 3,4-dimethylhexane-3-yl group, 3,5-dimethylhexane-3-yl group, 1-methylheptyl group, 2-methylheptyl group, 5-methylheptyl group Group, 2-methylheptan-2-yl group, 3-methylheptan-3-yl group, 4-methylheptan-3-yl group, 4-methylheptan-4-yl group, 1-ethylhexyl group, 2-ethylhexyl Group, 1-propylpentyl group, 2-propylpentyl group, 1,1-dimethylhexyl group, 1,4-dimethylhexyl group, 1,5-dimethylhexyl group, 1-ethyl-1-methylpentyl group, 1- Ethyl-4-methylpentyl group, 1,1,4-trimethylpentyl group, 2,4,4-trimethylpentyl group, 1-isopropyl-1,2-dimethylpropyl group, 1,1,3,3-tetramethyl Butyl group, n-nonyl group, 1-methyloctyl group, 6-methyloctyl group, 1-ethylheptyl group, 1- (n-butyl) pentyl group, 4-methyl-1- (n-propyl L) Pentyl group, 1,5,5-trimethylhexyl group, 1,1,5-trimethylhexyl group, 2-methyloctane-3-yl group, n-decyl group, 1-methylnonyl group, 1-ethyloctyl group 1- (n-butyl) hexyl group, 1,1-dimethyloctyl group, 3,7-dimethyloctyl group, n-undecyl group, 1-methyldecyl group, 1-ethylnonyl group, n-dodecyl group, n-tridecyl group Group, n-tetradecyl group, 1-methyltridecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, cyclopropyl group, cyclobutyl group , Cyclopentyl group, cyclohexyl group, cyclooctyl group and the like. From the viewpoint of availability, a substituted or unsubstituted C1-C8 saturated or unsaturated linear or branched alkyl group is preferable, and a methyl group and an ethyl group are particularly preferable.

Examples of the substituted or unsubstituted aryl group having 6 to 30 carbon atoms used as R ¹ , R ² , R ³ , R ⁴ , R ^{5 in the} chemical formula (1) include, for example, a phenyl group, Biphenyl group, 1-naphthyl group, 2-naphthyl group, 9-anthryl group, 9-phenanthryl group, 1-pyrenyl group, 5-naphthacenyl group, 1-indenyl group, 2-azurenyl group, 9-fluorenyl group, terphenyl Group, quarterphenyl group, mesityl group, pentarenyl group, binaphthalenyl group, tarnaphthalenyl group, quarternaphthalenyl group, heptaenyl group, biphenylenyl group, indacenyl group, fluoranthenyl group, acenaphthylenyl group, aceanthrylenyl group, phenenyl group, fluorenyl group Group, anthryl group, bianthracenyl group, teranthracenyl group , Quarter anthracenyl group, anthraquinolyl group, phenanthryl group, triphenylenyl group, pyrenyl group, chrysenyl group, naphthacenyl group, preadenyl group, picenyl group, perylenyl group, pentaphenyl group, pentacenyl group, tetraphenylenyl group, hexaphenyl group Group, hexacenyl group, rubicenyl group, coronenyl group, trinaphthylenyl group, heptaphenyl group, heptacenyl group, pyrantrenyl group, and oberenyl group.

Examples of the substituted or unsubstituted arylalkyl group having 7 to 31 carbon atoms used as R ¹ , R ² , R ³ , R ⁴ and R ^{5 in the} chemical formula (1) include, for example, a benzyl group Phenylethyl, 3-phenylpropyl, 1-naphthylmethyl, 2-naphthylmethyl, 2- (1-naphthyl) ethyl, 2- (2-naphthyl) ethyl, 3- (1-naphthyl) A propyl group, or a 3- (2-naphthyl) propyl group is exemplified.

Examples of the alkoxy group having 1 to 20 carbon atoms used as R ¹ , R ² , R ³ , R ⁴ , R ^{5 in the} chemical formula (1) include, for example, a methoxy group, an ethoxy group, an n-propoxy group, Examples include i-propoxy group, n-butoxy group, 2-methylpropoxy group, 1-methylpropoxy group, t-butoxy group and the like. Among these, those having 1 to 4 carbon atoms are preferable.

The above-mentioned substituted or unsubstituted saturated or unsaturated linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms The hydrogen atom in the group, substituted or unsubstituted arylalkyl group, and alkylene group may be further substituted with another substituent.

Examples of such substituents include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, alkyl groups such as methyl group, ethyl group, tert-butyl group and dodecyl group, phenyl group, p-tolyl. Group, xylyl group, cumenyl group, naphthyl group, anthryl group, aryl group such as phenanthryl group, alkoxy group such as methoxy group, ethoxy group, tert-butoxy group, aryloxy group such as phenoxy group, p-tolyloxy group, methoxy Alkoxycarbonyl groups such as carbonyl group, butoxycarbonyl group, phenoxycarbonyl, etc., acetoxy group, propionyloxy group, acyloxy group such as benzoyloxy group, acetyl group, benzoyl group, isobutyryl group, acryloyl group, methacryloyl group, methoxalyl group, etc. A Alkyl group, methylsulfanyl group, alkylsulfanyl group such as tert-butylsulfanyl group, arylsulfanyl group such as phenylsulfanyl group, p-tolylsulfanyl group, alkylamino group such as methylamino group, cyclohexylamino group, dimethylamino group, In addition to dialkylamino groups such as diethylamino group, morpholino group and piperidino group, arylamino groups such as phenylamino group and p-tolylamino group, hydroxy group, carboxy group, formyl group, mercapto group, sulfo group, mesyl group, p -Toluenesulfonyl group, amino group, nitro group, cyano group, trifluoromethyl group, trichloromethyl group, trimethylsilyl group, phosphinico group, phosphono group and the like.

As the imidazolium cation represented by the above formula (1), 1,3-disubstituted imidazolium cation and 1,2,3-trisubstituted imidazolium cation are preferably used from the viewpoint of easiness of synthesis. 1,3-disubstituted imidazolium cations are preferably used.
Specific examples of the imidazolium cation include 1-ethyl-3-methylimidazolium cation, 1,3-dimethylimidazolium cation, 1-methyl-3-propylimidazolium cation, and 1-butyl-3-methylimidazolium cation. 1-methyl-3-pentylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-heptyl-3-methylimidazolium cation, 1-methyl-3-octylimidazolium cation, 1-decyl-3 Dialkyl imidazolium cations such as methyl imidazolium cation, 1-dodecyl-3-methyl imidazolium cation, 1-ethyl-3-propyl imidazolium cation, 1-butyl-3-ethyl imidazolium cation; 3-ethyl-1 , 2-Dimethyl Imidazolium cation, 1,2-dimethyl-3-propylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 1,2-dimethyl-3-hexylimidazolium cation, 1,2-dimethyl-3 -Trialkylimidazolium cations such as octylimidazolium cation, 1-ethyl-3,4-dimethylimidazolium cation, and 1-isopropyl-2,3-dimethylimidazolium cation.

Examples of the pyrrolidinium cation include N, N-dimethylpyrrolidinium cation, N-ethyl-N-methylpyrrolidinium cation, N-methyl-N-propylpyrrolidinium cation, and N-butyl-N-methyl. Pyrrolidinium cation, N-methyl-N-pentylpyrrolidinium cation, N-hexyl-N-methylpyrrolidinium cation, N-methyl-N-octylpyrrolidinium cation, N-decyl-N-methylpyrrolidi Nium cation, N-dodecyl-N-methylpyrrolidinium cation, N- (2-methoxyethyl) -N-methylpyrrolidinium cation, N- (2-ethoxyethyl) -N-methylpyrrolidinium cation, N -(2-propoxyethyl) -N-methylpyrrolidinium cation, N- (2-isopro Kishiechiru) -N-, methyl pyrrolidinium cation can be exemplified.

Examples of the pyridinium cation include a pyridinium cation substituted with an alkyl group having 1 to 16 carbon atoms such as an N-methylpyridinium cation, an N-ethylpyridinium cation, an N-butylpyridinium cation, and an N-propylpyridinium cation. Can do.

Examples of piperidinium cations include N, N-dimethylpiperidinium cation, N-ethyl-N-methylpiperidinium cation, N-methyl-N-propylpiperidinium cation, and N-butyl-N-methyl. Piperidinium cation, N-methyl-N-pentylpiperidinium cation, N-hexyl-N-methylpiperidinium cation, N-methyl-N-octylpiperidinium cation, N-decyl-N-methylpiperidi Nium cation, N-dodecyl-N-methylpiperidinium cation, N- (2-methoxyethyl) -N-methylpiperidinium cation, N- (2-methoxyethyl) -N-ethylpiperidinium cation, N -(2-Ethoxyethyl) -N-methylpiperidinium cation, N-methyl-N- (2 Methoxyphenyl) piperidinium cation, N-methyl-N- (4-methoxyphenyl) piperidinium cation, N-ethyl-N- (2-methoxyphenyl) piperidinium cation, N-ethyl-N- (4 -Methoxyphenyl) piperidinium cation.

It does not specifically limit regarding the anion part of an ionic liquid (1), It is possible to use the anion used with a general ionic liquid. For example, as the anion moiety, Cl ⁻ , Br ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) n ⁻ , (CN) ₂ N ⁻ , SCN ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ ) (CF ₃ CO ) N ^- it is possible to use an anion commonly used in ionic liquids such as.
Among these, an anion having a halogen atom is preferable, a fluorine atom-containing anion is particularly preferable, and a fluorine-containing imide anion represented by the following general formula (2) is preferably used.

(C _n F _{2n + 1} SO ₂ ) ₂ N ⁻ (2)
(Where n is an integer from 0 to 15)

Specifically, as the fluorine-containing imide anion represented by the general formula (2), it is preferable to use a bis (trifluoromethanesulfonyl) imide anion or a bis (fluorosulfonyl) imide anion. The above n is usually 0 to 15, preferably 0 to 8, particularly preferably 0 to 4.

The method for producing the ionic liquid is not particularly limited. For example, a known method such as an anion exchange method or an acid ester method can be applied as the production method. More specifically, for example, it can be obtained by an anion exchange reaction using a halogenated salt of an organic cation to be used and an alkali metal salt of a perfluoroalkylsulfonate anion. The halogen of the halogenated salt includes chlorine or bromine. Examples of the alkali metal of the alkali metal salt include sodium and potassium.

(4.2) Organic solvent The organic solvent contained in the electrolyte is not particularly limited. The organic solvent is preferably a polar solvent from the viewpoint that it is easy to dissolve citric acid. Examples of the polar solvent include acetonitrile, ethanol, isopropanol, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N, N-dimethylacetamide, tetrahydrofuran (THF), methyl triglycol diester succinate, acetone, Acetic acid etc. are mentioned, These 1 type can be used individually or in combination of 2 or more types.

(4.3) Volume ratio between ionic liquid and organic solvent The volume ratio between the ionic liquid and the organic solvent is not particularly limited. The volume ratio of the ionic liquid to the organic solvent is preferably 90:10 to 10:90, more preferably 60:40 to 40:60, and still more preferably 55:45 to 45:55. . Within this range, citric acid can be sufficiently dissolved in the electrolyte.

(4.4) Silver ion Although it does not specifically limit as a silver ion source, Silver nitrate, silver sulfate, etc. are mentioned as what is generally easy to obtain. Use of these is desirable also in terms of versatility and cost.
The concentration of silver ions in the electrolyte is not particularly limited. The concentration of silver ions is preferably 0.01 to 2.0M, more preferably 0.02 to 0.8M, and still more preferably 0.1 to 0.3M. When the concentration of silver ions is within this range, a sufficient amount of current that can be passed through the electrolyte for reversible reaction can be secured.

(4.5) Citric acid In the present invention, by containing citric acid in the electrolyte, formation of a silver coating by electrolytic plating and elution of the silver coating by electrolytic elution can be performed reversibly.
The concentration of citric acid in the electrolyte is not particularly limited. The concentration of citric acid is preferably 0.5 to 1000 mM, more preferably 5 to 250 mM, and still more preferably 20 to 100 mM as citric acid monohydrate. When the citric acid concentration is within this range, the formation of the silver coating by electrolytic plating and the elution of the silver coating by electrolysis can be sufficiently performed, and the characteristics of the light control member are improved.

(4.6) Other components The electrolyte may contain other components as long as the effects of the present invention are not impaired.

(4.7) Current density during electroplating The current density during electroplating is not particularly limited. The current density during electrolytic plating is preferably 0.5 to 20 mA / cm ² , more preferably 1 to 10 mA / cm ² , and further preferably 2 to 5 mA / cm ² . When the current density during electrolytic plating is within this range, the silver coating can be sufficiently formed by electrolytic plating, and the characteristics of the light control member are improved.

(4.8) Current density during electrolysis The current density during electrolysis is not particularly limited. Current density during electrolysis elution is preferably 0.1 ~ 10mA / cm ^2, more preferably 0.4 ~ 6mA / cm ^2, more preferably from 1 ~ 4mA / cm ^2. When the current density during electrolytic elution is within this range, the silver coating can be sufficiently eluted by electrolytic elution, and the characteristics of the light control member are improved.

2. Effect of Light Control Member of this Embodiment The light control member of this embodiment can reversibly form a silver coating by electrolytic plating and elution of a silver coating by electrolytic elution. And the reflectance of visible light can be changed by this reversible reaction. Since the light control member of this embodiment is a novel light control member, the application range of a light control member spreads.

Hereinafter, the present invention will be described in more detail with reference to examples.

1. Silver electroplating test and electrolysis elution test Silver electroplating test and electrolysis elution test were performed using the apparatus shown in FIG. Here, reference numeral 3 indicates a dimming electrode, reference numeral 5 indicates a counter electrode, reference numeral 7 indicates an electrolyte, reference numeral 9 indicates a reference electrode, and reference numeral 11 indicates a potentiostat.

(1) Electrolyte 6 mL of electrolyte was prepared with the following composition. The “electrolyte” may be referred to as “Ag plating bath” as described above. The ionic liquid used is 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide.

<Composition of electrolyte>
0.2M AgNO ₃
40 mM citric acid monohydrate acetonitrile 2.9 mL
Ionic liquid 3.1mL

(2) Electrode The following were used as each electrode.
(2.1) Dimming electrode (working electrode)
As the light control electrode, an ITO electrode adhered in a state where Pd nanoparticles were dispersed was used. Plating bath composition is 0.049M PdCl ₂ for dispersing covering the Pd nanoparticles on the ITO _{_{electrode, 0.765M NH 4 OH, 0.44M NH}} 4 H 2 PO 4, 0.237M NH 4 a Cl 4 mL _{H 2} Dissolved in O. Using a potentiostat, palladium ion electroplating was performed by constant current electrolysis using a transparent conductive ITO electrode as a working electrode, an Ag / Ag ⁺ electrode as a reference electrode, and a Pt electrode as a counter electrode. At this time, a high current (−5 to −20 mA / cm ² ) is applied for a short time (0.25 to 3 s) to strike Pd ²⁺ to perform size control and dispersion degree control of Pd nanoparticles. An ITO electrode adhered with dispersed Pd nanoparticles of size was prepared. These ITO electrodes were used as dimming electrodes.
3A shows the ITO electrode 15 before the Pd nanoparticle 13 is dispersedly coated, and FIG. 3B shows the light control electrode 3 as the ITO electrode 15 after the Pd nanoparticle 13 is dispersedly coated. Indicates. That is, in this experiment, the dimming electrode 3 of FIG. 3 (B) was used.

(2.2) Reference electrode An Ag / Ag ⁺ electrode was used as a reference electrode.
(2.3) Counter electrode A silver electrode (silver wire) was used as the counter electrode.

(3) Test (3.1) Test 1 (Test using an electrolyte containing citric acid)
Electrolytic plating was performed for a predetermined time (25 s) at a constant current (−4 mA / cm ² ) on the various transparent light control electrodes prepared in (2.1) above. As a result, in any case, a silver film having a mirror surface on the dimming electrode was formed.
Next, using the dimming electrode on which the silver coating was formed, electrolytic dissolution of the silver coating was performed under the conditions of constant current density (+1 mA / cm ² ) and predetermined time (100 s). As a result, in any case, it was confirmed that the silver coating was eluted from the light control electrode on which the silver coating was formed, and returned to the transparent original light control electrode.
The appearance of this test is schematically shown in FIG. In the electrolytic plating, the silver coating 17 is coated from the state shown in FIG. 3B to the state shown in FIG. In the electrolytic elution, the silver coating 17 is eluted from the state shown in FIG. 3C to the state shown in FIG. In this way, the reflectance of visible light can be changed by reversibly performing the formation of the silver coating 17 by electrolytic plating and the elution of the silver coating 17 by electrolytic elution.

(3.2) Test 2 (Test using an electrolyte without citric acid)
An experiment similar to the above experiment (3.1) was performed under the same conditions except that citric acid was removed from the electrolyte. As a result, a silver white film was formed on the ITO electrode adhered with the Pd nanoparticles dispersed. It was. When the surface was observed with an electron microscope, hemispherical polygonal silver crystals were formed, which looked white due to light scattering. For this reason, it was confirmed that citric acid is essential as an additive in order to obtain a mirror gloss. In the absence of citric acid, silver crystals grow isotropically and form a hemispherical surface, but the presence of citric acid results in anisotropic growth, and the silver crystals grow in a planar shape, resulting in a mirror surface. Presumably glossy.

(3.3) Test 3 (Test using an electrolyte containing 2-hydroxypyridine)
The experiment was conducted using 2-hydroxypyridine instead of citric acid. Specifically, 6 mL of electrolyte was prepared with the following composition. The ionic liquid used is 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide.

<Composition of electrolyte>
0.2M AgNO ₃
0.4M 2-hydroxypyridine acetonitrile 2.9mL
Ionic liquid 3.1mL

When 2-hydroxypyridine was used as an additive instead of citric acid, a silver film having a specular gloss was formed. However, even when electrolytic elution was performed, the original transparent dimming electrode did not return and a gray coating remained. Furthermore, the electrolyte turned brown by electrolytic oxidation of 2-hydroxypyridy. On the other hand, in the case of using the citric acid described above ((3.1) Test 1), the plating bath remained transparent even after electrolytic elution. From this, it was confirmed that the present invention is suitable for a dimming smart window and the like.

(3.4) Test 4 (Experiment using an ITO electrode to which Pd nanoparticles are not attached)
When a similar experiment was performed using an ITO electrode to which no Pd nanoparticle adhered, a silver coating could be formed, but a matte silver coating with slightly less specular gloss was obtained. Therefore, in order to improve the specular gloss of the silver coating, it has been found that it is preferable to attach Pd nanoparticles to the ITO electrode.

2. Examination of Pd nano-particles adhered to ITO electrode (1) Examination of average Pd surface density As described in (2.1) above, the Pd strike plating conditions were -5 to -20 mA / cm ² and 0 .25 to 3 s is applied. The average visible light transmittance of the ITO electrode to which the Pd nanoparticle prepared under such various conditions adhered was measured. The results are shown in Table 1.
In Table 1, “ITO only” means an ITO electrode to which no Pd nanoparticles are attached, and “Pd (−5 mA, 1 s)” means an ITO electrode manufactured under the conditions of −5 mA / cm ² , 1 s. “Pd (−10 mA, 1 s)” means an ITO electrode manufactured under the condition of −10 mA / cm ² , 1 s, and “Pd (−10 mA, 3 s)” means −10 mA / cm ² , 3 s. It means an ITO electrode manufactured under conditions.

From the results of Table 1, when the average Pd surface density is 5.5 × 10 ⁻⁶ g / cm ² , the average visible light transmittance is not so low as compared to the ITO electrode to which no Pd nanoparticles are attached. It was practical. Therefore, it was found that the average Pd surface density is preferably in the range of 1.0 × 10 ⁻⁶ to 9.0 × 10 ⁻⁶ g / cm ² .

(2) Examination of average particle diameter of Pd nanoparticle Next, the amount of electrodeposition was made constant at 5 mC / cm ² , the current density was changed, and the average particle diameter of Pd nanoparticle was measured. Further, the dispersibility of the Pd nanoparticle on the ITO electrode was observed with a scanning electron microscope (SEM). The results are shown in Table 2.
In Table 2, “Pd (−5 mA, 1 s)” means an ITO electrode manufactured under the conditions of −5 mA / cm ² and 1 s, and “Pd (−10 mA, 0.5 s)” means −10 mA / It means an ITO electrode manufactured under conditions of cm ² and 0.5 s, and “Pd (−20 mA, 0.25 s)” means an ITO electrode manufactured under conditions of −20 mA / cm ² and 0.25 s.

From the results in Table 2, it was confirmed that the dispersibility was high when the average particle diameter of the Pd nanoparticle was 42 nm. Further, using this electrode, electrolytic plating was performed at a constant current (−4 mA / cm ² ) for a predetermined time (25 s). As a result, a very uniform silver film having a mirror surface on the dimming electrode was formed. Therefore, it was confirmed that a very uniform silver coating was formed by setting the average particle size of the Pd nanoparticle within the range of 5 to 70 nm.

3. Summary It was confirmed that the formation of a silver coating by electrolytic plating and the elution of a silver coating by electrolytic elution can be performed reversibly by using an electrolyte containing citric acid.
In order to increase the specular gloss of the silver coating, it has been found preferable to attach Pd nanoparticles to the ITO electrode.

The above examples are for illustrative purposes only and are not to be construed as limiting the invention. Although the invention has been described with reference to exemplary embodiments, it is to be understood that the language used in the description and illustration of the invention is illustrative and exemplary rather than limiting. As detailed herein, modifications may be made in its form within the scope of the appended claims without departing from the scope or spirit of the invention. Although specific structures, materials and examples have been referred to in the detailed description of the invention herein, it is not intended to limit the invention to the disclosure herein, but rather, the invention is claimed. It covers all functionally equivalent structures, methods and uses within the scope.

The present invention is not limited to the embodiments described in detail above, and various modifications or changes can be made within the scope of the claims of the present invention.

Since the light control member of the present invention has a novel structure, it is effective for expanding the application range of the light control member.

DESCRIPTION OF SYMBOLS 1 ... Light control member 3 ... Light control electrode 5 ... Counter electrode 7 ... Electrolyte 9 ... Reference electrode 11 ... Potentiostat 13 ... Pd nanoparticle 15 ... ITO electrode 17 ... Silver coating

Claims

A light control member,
A dimming pole,
The opposite pole,
An electrolyte sandwiched between the dimming electrode and the counter electrode,
The light control member, wherein the electrolyte contains an ionic liquid, an organic solvent, silver ions, and citric acid.
2. The light control according to claim 1, wherein the light-controlling ratio is configured to change the reflectance of visible light by reversibly performing formation of a silver coating by electroplating and elution of the silver coating by electrolytic elution. Element.
The light control member according to claim 2, wherein the silver film has a mirror surface.
The light control member according to any one of claims 1 to 3, wherein the cation portion of the ionic liquid is represented by the following general formula (1).

[In formula (1), R 1 , R 2 , R 3 , R 4 , R 5 are each independently
Hydrogen atom,
A substituted or unsubstituted C1-C20 saturated or unsaturated linear, branched, or cyclic alkyl group,
A substituted or unsubstituted aryl group having 6 to 30 carbon atoms,
A substituted or unsubstituted arylalkyl group having 7 to 31 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms,
When the alkyl group, the aryl group or the arylalkyl group is substituted, a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acyl group, an alkylsulfanyl group, Arylsulfanyl, alkylamino, dialkylamino, arylamino, hydroxy, carboxy, formyl, mercapto, sulfo, mesyl, p-toluenesulfonyl, amino, nitro, cyano, tri Substituted with a fluoromethyl group, a trichloromethyl group, a trimethylsilyl group, a phosphinico group, or a phosphono group. ]
The light control member according to any one of claims 1 to 4, wherein the organic solvent is a polar solvent.
The light control member according to any one of claims 1 to 5, wherein a volume ratio of the ionic liquid to the organic solvent is 90:10 to 10:90.
The light control member according to any one of claims 1 to 6, wherein the light control member is used as a light control smart window, a light control mirror, or a design part.