JP2006011000A - Optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element having excellent repetition stability and high contrast by using a chargeable polymer gel which causes changes in the volume by the effect of an electric field. <P>SOLUTION: The optical element has at least a pair of electrode substrates 2, 4 sandwiching a colored electric insulating liquid 6 having ≥10<SP>3</SP>Ωcm volume resistivity and chargeable polymer gel particles 8 which absorb or release the electric insulating liquid 6 to expand or shrink by application of an electric field. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel optical element utilizing the electric field response volume change of a polymer gel. The present invention is useful as a light modulation element, a display element, a dimming element, and the like.

With the advancement of the advanced information society, the need for display elements is increasing. In addition to the conventional CRT and liquid crystal, new display technologies such as organic EL and plasma have been developed. Furthermore, various researches for the development of new technologies aimed at realizing further cost reduction, larger area, lighter weight, more flexible, reflective display elements with printing level brightness, etc. are underway. Yes.
In particular, a reflective display element having a printing level brightness is expected to realize a display element such as paper (referred to as electronic paper or digital paper). On the other hand, there is a great need for an inexpensive large-area color display system or an inexpensive large-area display system, but the current technology has not been established.

As one of these techniques, a technique using a stimulus-responsive polymer gel is also disclosed. For example, when a polymer gel that changes volume electrically and a colored liquid are sandwiched between two electrode substrates and the gel swells, the transparent color of the gel is observed by the observer when the gel swells. An optical element that can observe the color of a liquid is disclosed (for example, see Patent Documents 1 and 2).
In addition, when a colored polymer gel that changes volume electrically and a transparent liquid are sandwiched between two electrode substrates, and the gel swells, the gel-containing pigment concentration becomes thin so that light is transmitted and reversed. An optical element utilizing the fact that the pigment concentration inside the gel increases when it contracts to absorb the light passing therethrough is disclosed (for example, see Patent Documents 3 and 4).

On the other hand, an optical element having a configuration similar to Patent Documents 1 to 4 made of a dot-like electric field response gel formed by photopolymerization and a colored liquid is disclosed (for example, see Patent Document 5).
Moreover, some other optical elements are disclosed about the optical element of the structure similar to the said patent documents 1-4 (for example, refer patent documents 6-10).

  However, the optical element has the following common problems. That is, since the optical element uses an aqueous solution as the liquid, the liquid is decomposed by energization, and bubbles are generated or discolored, so that the repetition characteristics are lacking. This is a problem on the fundamental driving principle that deformation and volume change of a conventionally known stimulus-responsive polymer gel are induced by pH or ion concentration change induced by liquid electrolysis.

  In the optical elements disclosed in Patent Documents 3 and 4, since the gel at the time of contraction absorbs light, the area occupied by the gel at the time of contraction is small, so the light is absorbed. There is a problem that the contrast is further lowered due to low efficiency and coloring at the time of swelling and shrinking.

Furthermore, in the optical element disclosed in Patent Document 7, a conductive polymer compound is provided on the electrode substrate surface, but since the conductive polymer is generally colored, color reproducibility and contrast There is a problem of lowering.
JP 61-149926 A JP 61-149927 A JP 61-149928 A JP 61-149929 A JP 63-13021 A JP-A-9-160081 JP 2002-107772 A JP 2002-156665 A JP 2002-287183 A JP 2002-296625 A

  An object of the present invention is to solve the above problems and achieve the following object. That is, an object of the present invention is to provide an optical element having a high contrast and having excellent repetitive stability using a chargeable polymer gel that undergoes a volume change by the action of an electric field.

The above problems are solved by the present invention described below.
That is, the present invention
<1> A volumetric resistivity of 10 ³ Ωcm or more, a colored electrically insulating liquid, and a chargeable polymer gel that expands and contracts by absorbing and releasing the electrically insulating liquid when an electric field is applied An optical element having at least a pair of electrode substrates sandwiching particles.

<2> The optical element according to <1>, wherein the chargeable polymer gel particles are fixed to at least one of the pair of electrode substrates.
<3> A distance L between a pair of electrode substrates sandwiching the electrically insulating liquid and the chargeable polymer gel particles, an average particle diameter d ₀ of the chargeable polymer gel particles when contracted, and the above when expanded <1> or <2>, wherein the average particle diameter d of the chargeable polymer gel particles satisfies the following relationship.
d ₀ <L <d

<4> The optical element according to any one of <1> to <3>, wherein the chargeable polymer gel particles contain a light control material.
<5> The optical element according to any one of <1> to <4>, wherein the chargeable polymer gel particles are ionic polymer gel particles.

<6> The optical element according to any one of <1> to <4>, wherein the chargeable polymer gel particles are ionic polymer gel particles containing a charging agent.
<7> The optical element according to any one of <1> to <4>, wherein the chargeable polymer gel particles are nonionic polymer gel particles containing a charging agent.

  According to the present invention, it is possible to provide an optical element having a high contrast and having excellent repetitive stability using a chargeable polymer gel that undergoes volume change by the action of an electric field.

The optical element of the present invention has a volume resistivity of 10 ³ Ωcm or more, a colored electrically insulating liquid, and a charge that expands and contracts by absorbing and releasing the electrically insulating liquid when an electric field is applied. And at least a pair of electrode substrates sandwiching the conductive polymer gel particles.

In the present invention, the chargeable polymer gel particles can cause a reversible large volume change in accordance with the electric field in the colored electrically insulating liquid. Therefore, as will be described later, the change in absorption cross-section when the chargeable polymer gel particles are viewed from the normal direction of the electrode substrate during expansion and contraction in the colored electrically insulating liquid. Therefore, the optical characteristics can be greatly changed, and can be applied to optical elements such as a light control element and a display element.
In addition, optical characteristics can be further changed by incorporating a light-controlling material such as a pigment or a dye into the chargeable polymer gel particles.
On the other hand, in the optical element of the present invention, bubbles are prevented from being generated due to the electrolysis of the liquid due to the electrochemical reaction, by using an element configuration in which the chargeable polymer gel particles are used in a highly insulating liquid. The optical characteristics are not impaired by energization. As a result, an optical element having excellent repeated stability and high contrast can be provided.

Hereinafter, the optical element of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is provided to the member which has the same function throughout all drawings, and the description may be abbreviate | omitted.
First, the first embodiment of the optical element of the present invention will be described with reference to FIGS. FIG. 1 is a schematic sectional view of a first embodiment of the optical element of the present invention. Specifically, FIG. 1A is a schematic cross-sectional view of the charged polymer gel particles in a contracted state, and FIG. 1B is a schematic cross-sectional view of the charged polymer gel particles in an expanded state. . As shown in FIG. 1A, the pair of electrode substrates 2 and 4 sandwich the colored electrically insulating liquid 6 and the chargeable polymer gel particles 8.

Also, chargeable polymer particles 8 is fixed to the electrode substrate 4, the distance L between the electrode substrate 2 4 than the average particle diameter d ₀ of the chargeable polymer 8 long (d ₀ < L). Therefore, when observed from the normal direction of the electrode substrate 2, the gap between the electrode substrate 2 and the chargeable polymer gel particles 8 is filled with the colored electrically insulating liquid 6, and as shown in FIG. The color of the colored electrically insulating liquid 6 is observed by the observer. FIG. 2 is an external view as seen from the normal direction of the electrode substrate 2 in the first embodiment of the optical element of the present invention. Specifically, FIG. 2A is an external view seen from the normal direction of the electrode substrate 2 in a state where the charged polymer gel particles are contracted, and FIG. It is the external view seen from the normal line direction of the electrode substrate 2 of the expanded state.

  In the optical element in the state shown in FIG. 1A, as shown in FIG. 1B, an electric field is applied between the electrode substrates 2 and 4 so that the chargeable polymer gel particles 8 expand. The charged polymer gel particles 8 are pressed against the electrode substrate 2. This is because, originally, the chargeable polymer gel particles have the property of isotropic expansion, but in the first embodiment of the optical element of the present invention, the chargeability when isotropically expanded. Since the average particle diameter d of the polymer gel particles 8 is longer than the distance L between the electrode substrates 2 and 4 (L <d), the polymer gel particles 8 are not allowed to expand isotropically. 8 is pressed against the electrode substrate 2. As a result, the colored electrically insulating liquid filled in the gap between the electrode substrate 2 and the chargeable polymer gel particles 8 is pushed away, and is viewed from the normal direction of the electrode substrate 2 as shown in FIG. In this case, the color of the chargeable polymer gel particles 8 is observed.

In the optical element shown in FIG. 1, the chargeable polymer gel particles 8 are fixed to the electrode substrate 4 (only one electrode substrate) and satisfy the relationship of d ₀ <L <d. The optical element does not necessarily have the above-described aspect. Specifically, the chargeable polymer gel particles 8 may not be fixed to the electrode substrate 4 and may not satisfy the relationship d ₀ <L <d. However, the chargeable polymer gel particle 8 is fixed to the electrode substrate in that it can have a higher contrast (more preferably, as shown in FIG. It is preferably fixed only to the electrode substrate (only the electrode substrate 4). Further, it is preferable that the relationship d ₀ <L <d is satisfied. Further, it is more preferable that the chargeable polymer gel particles 8 are fixed to one electrode substrate and satisfy the relationship of d ₀ <L <d.

  In the first embodiment of the optical element of the present invention, as shown in FIG. 3 and FIG. 4, the degree of expansion (size) of the chargeable polymer gel particles 8 is controlled by controlling the strength of the electric field applied depending on the location. By changing stepwise, it is possible to change the area of the chargeable polymer gel particles 8 that are pressed against the electrode substrate 2 depending on the location, and it is also possible to change the color tone in gradation. FIG. 3 is a schematic cross-sectional view of the state where the charged polymer gel particles are expanded when the strength of the electric field applied is controlled depending on the location in the first embodiment of the optical element of the present invention. FIG. 4 is an external view seen from the normal direction of the electrode substrate 2 when the intensity of the electric field applied is controlled depending on the location in the first embodiment of the optical element of the present invention.

  Next, a second embodiment of the optical element of the present invention will be described with reference to FIGS. FIG. 5 is a schematic sectional view of a second embodiment of the optical element of the present invention. Specifically, FIG. 5 (a) is a schematic cross-sectional view of a state where the transparent chargeable polymer gel particles are contracted, and FIG. 5 (b) is a schematic cross-sectional view of a state where the transparent chargeable polymer gel particles are expanded. It is. The second embodiment of the optical element of the present invention is the same as the first embodiment of the optical element of the present invention except that the transparent chargeable polymer gel particle 8 ′ is used as the chargeable polymer gel particle. It becomes the composition of. Therefore, when observed from the normal direction of the electrode substrate 2, the colored electrically insulating liquid 6 is filled in the gap between the electrode substrate 2 and the transparent chargeable polymer gel particles 8 ′, and therefore, as shown in FIG. Thus, the color of the colored electrically insulating liquid 6 is observed by the observer. FIG. 6 is an external view as seen from the normal direction of the electrode substrate 2 in the second embodiment of the optical element of the present invention. Specifically, FIG. 6A is an external view seen from the normal direction of the electrode substrate 2 in a state where the chargeable polymer gel particles are contracted, and FIG. It is the external view seen from the normal line direction of the electrode substrate 2 of the expanded state. In FIGS. 5 and 6, an arrow represents light irradiated from the electrode substrate 4 side.

In the second embodiment of the optical element of the present invention, an electric field is applied between the electrode substrates 2 and 4 so that the transparent chargeable polymer gel particles 8 ′ expand, so that FIG. As shown, the transparent chargeable polymer gel particles 8 ′ are pressed against the electrode substrate 2. At this time, since the colored electrically insulating liquid 6 filled in the gap between the electrode substrate 2 and the transparent chargeable polymer gel particles 8 ′ is pushed away, as shown in FIG. Light transmission is possible at the portion where the particle 8 ′ is pressed, and application as a transmissive optical element is possible.
Also, in the second embodiment of the optical element of the present invention, as in the first embodiment of the optical element of the present invention, by controlling the strength of the electric field applied depending on the location, a high transparent chargeability can be obtained. It is possible to control the amount of transmitted light by changing the degree of expansion of the molecular gel particles 8 ′ depending on the location.
In the above figures, the shape of the chargeable polymer gel particle 8 and the transparent chargeable polymer gel particle 8 ′ is spherical, but the shape is not limited to this as described later.

The chargeable polymer gel particles in the present invention will be described.
In the present invention, the chargeable polymer gel particles are defined as ionic polymer gel particles, ionic polymer gel particles containing a charging agent, and nonionic polymer gel particles containing a charging agent. Here, the ionic polymer gel particle means a polymer gel particle having no ion dissociation group in the polymer chain, and the nonionic polymer gel is a polymer gel particle having no ion dissociation group in the polymer chain. Say.

<1> Ionic polymer gel particles Examples of the ionic polymer gel constituting the ionic polymer gel particles include cross-linked poly (meth) acrylic acid and salts thereof, (meth) acrylic acid and (meta ) Copolymers and salts of copolymers with acrylamide, hydroxyethyl (meth) acrylate, alkyl (meth) acrylate, etc., crosslinks and salts of polymaleic acid, maleic acid and (meth) acrylamide, hydroxyethyl ( Cross-linked products and salts of copolymers with (meth) acrylates, alkyl (meth) acrylates, etc., cross-linked products of polyvinyl sulfonic acid, vinyl sulfonic acid and (meth) acrylamide, hydroxyethyl (meth) acrylate, (meth) Cross-linked products of copolymers with acrylic acid alkyl esters, etc., cross-linked products of polyvinylbenzene sulfonic acid And salts thereof, crosslinked products of copolymers of vinylbenzene sulfonic acid and (meth) acrylamide, hydroxyethyl (meth) acrylate, alkyl (meth) acrylate, etc., and salts thereof, crosslinked products of polyacrylamide alkyl sulfonic acid, Cross-linked products and salts of such salts, acrylamide alkyl sulfonic acids and copolymers of (meth) acrylamide, hydroxyethyl (meth) acrylate, alkyl (meth) acrylate, and polydimethylaminopropyl (meth) acrylamide And its hydrochloride, dimethylaminopropyl (meth) acrylamide and (meth) acrylic acid, (meth) acrylamide, hydroxyethyl (meth) acrylate, (meth) acrylic acid alkyl ester cross-linked products and their Quaternized compounds, salts, polydi Cross-linked products of tilaminopropyl (meth) acrylamide and polyvinyl alcohol, quaternized products and salts thereof, cross-linked products of poly (meth) acrylic acid and salts thereof, carboxyalkyl cellulose salts Cross-linked products, partial hydrolysates of cross-linked products of poly (meth) acrylonitrile, salts thereof, and the like. Among these, cross-linked products of poly (meth) acrylic acid salts with (meth) acrylamide, poly (meth) acrylic acid A crosslinked product of the salt of and hydroxyethyl (meth) acrylate is preferred.
In this specification, “(meth) acryl” or the like means “acryl” or “methacryl” or the like.
These ionic polymer gels are prepared by adding a cross-linking agent, or by irradiating the polymer with radiation such as electron beam or γ-ray, heating, and adding a peroxide to form a three-dimensional cross-link. can do.

<2> Ionic polymer gel particles containing charging agent The ionic polymer gel constituting the ionic polymer gel particles containing the charging agent is the same ionicity as described in <1>. A polymer gel can be used.
Examples of the charging agent contained in the ionic polymer gel include various amphiphilic (high) molecules, nigrosine compounds, alkoxylated amines, quaternary ammonium salts, alkylamides, phosphorus and tungsten, and compounds, Molybdenum chelate pigments, hydrophobic silica, borons, halogen compounds, metal complexes of monoazo dyes, salicylic acid, alkylsalicylic acid, dialkylsalicylic acid, metal complexes of naphthoic acid, chlorinated polyolefins, chlorinated polyesters, excess acid group polyesters, copper phthalocyanines Sulfonylamine, oil black, naphthenic acid metal salt, fatty acid metal salt, resin acid soap and the like, and the charging agent may be the same as the light control material described later. As the charging agent, various amphiphilic (high) molecules and pigments are preferable.

The addition amount of the charging agent contained in the ionic polymer gel particles is preferably in the range of 2 to 70% by mass, and more preferably in the range of 5 to 50% by mass. When the addition amount of the charging agent is less than 2% by mass, the charge amount of the gel may be lowered and the response speed may be reduced. When the addition amount of the charging agent is more than 70% by mass, the rubber elasticity of the gel May be damaged and the responsiveness may decrease.

<3> Nonionic Polymer Gel Particles Containing Charging Agent The nonionic polymer gel constituting the nonionic polymer gel particles containing the charging agent is selected from the monomers listed below: A cross-linked product of a homopolymer composed of two or more types of monomers and a cross-linked product of a copolymer composed of two or more types of monomers can be preferably used. Specifically, (meth) acrylonitrile, (meth) acrylic acid alkyl ester, (meth) acrylic acid dialkylaminoalkyl ester, (meth) acrylamide, ethylene, propylene, butadiene, isoprene, isobutylene, N-dialkyl substituted (meth) Acrylamide, vinylpyridine, vinylamine, allylamine, styrene, vinylcarbazole, vinylpyrrolidone, styrene, styrene derivatives, ethylene glycol di (meth) acrylate, glyceryl (meth) acrylate, polyethylene glycol mono (meth) acrylate, vinyl chloride, vinylidene chloride, Ethylene glycol di (meth) acrylate, methylenebisacrylamide, isoprene, butadiene, ethylene glycol di (meth) acrylate, diethylene Rikoruji (meth) acrylate, butanediol di (meth) acrylate, are exemplified such as hexanediol di (meth) acrylate, this also (meth) acrylic acid alkyl esters in, N- dialkyl substituted (meth) acrylamide is preferable.
Furthermore, a crosslinked body of a polyester polymer, a crosslinked body of a polyvinyl acetal derivative, a crosslinked body of a polyurethane polymer, a crosslinked body of a polyurea polymer, a crosslinked body of a polyether polymer, a crosslinked body of a polyamide polymer, A crosslinked product of a polycarbonate-based polymer can also be preferably used.

  These nonionic polymer gels can be cross-linked three-dimensionally by adding a crosslinking agent, or by irradiating the polymer with radiation such as electron beam or γ-ray, heating, or adding peroxide. Can be produced.

  On the other hand, the charging agent contained in the nonionic polymer gel is the same as the charging agent contained in the ionic polymer gel, and the amount used thereof is also the same.

As described above, a light adjusting material can be added to and contained in the chargeable polymer gel particles.
Specific examples of the light control material include dyes, pigments, and light scattering materials. Further, it is preferable that the light control material is physically or chemically fixed in the chargeable polymer gel particles.
Preferred specific examples of the dye include, for example, black nigrosine dyes, azo dyes that are color dyes such as red, green, blue, cyan, magenta, yellow, anthraquinone dyes, indigo dyes, phthalocyanine dyes, Examples thereof include carbonium dyes, quinone imine dyes, methine dyes, quinoline dyes, nitro dyes, benzoquinone dyes, naphthoquinone dyes, naphthalimide dyes, and verinone dyes, and those having a high light absorption coefficient are preferred.

  Specific examples of the dye include C.I. I. Direct yellow-1, 8, 11, 12, 24, 26, 27, 28, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 157; I. Acid Yellow-1, 3, 7, 11, 17, 19, 23, 25, 29, 38, 44, 79, 127, 144, 245; I. Basic yellow-1, 2, 11, 34; I. Food Yellow-4; C.I. I. Reactive Yellow-37; I. Solvent Yellow-6, 9, 17, 31, 35, 100, 102, 103, 105; I. Direct Red-1, 2, 4, 9, 11, 13, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 80, 81, 83 84, 89, 95, 99, 113, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230, 231; I. Acid Red-1, 6, 8, 9, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 85, 87, 89, 92, 97, 106, 111, 114, 115, 118 134, 158, 186, 249, 254, 289; I. Basic red-1, 2, 9, 12, 14, 17, 18, 37; I. Food red-14; I. Reactive Red-23, 180; C.I. I. Solvent Red-5, 16, 17, 18, 19, 22, 23, 143, 145, 146, 149, 150, 151, 157, 158; C.I. I. Direct Blue-1, 2, 6, 15, 22, 25, 41, 71, 76, 78, 86, 87, 90, 98, 163, 165, 199, 202; I. Acid Blue-1, 7, 9, 22, 23, 25, 29, 40, 41, 43, 45, 78, 80, 82, 92, 93, 127, 249; I. Basic blue-1, 3, 5, 7, 9, 22, 24, 25, 26, 28, 29; I. Food Blue-2; C.I. I. Solvent Blue-22, 63, 78, 83-86, 191, 194, 195, 104; C.I. I. Direct Black-2, 7, 19, 22, 24, 32, 38, 51, 56, 63, 71, 74, 75, 77, 108, 154, 168, 171; I. Acid Black-1, 2, 7, 24, 26, 29, 31, 44, 48, 50, 52, 94; C.I. I. B. Basic Black-2, 8; I. Food Black-1, 2; C.I. I. Reactive Black-31, C.I. I. Food violet-2, C.I. I. Solvent Violet-31, 33, 37, C.I. I. Solvent Green-24, 25, C.I. I. Solvent Brown-3, 9 etc. are mentioned. These dyes may be used alone, or may be mixed and used to obtain a desired color.

  In addition, in order to immobilize the dye on the chargeable polymer gel particles, a dye having a structure having a polymerizable group such as an unsaturated double bond group or a so-called reactive dye capable of reacting with the polymer gel is used. Preferably used. Moreover, the preferable density | concentration of the dye contained in the said charging polymer gel particle is the range of 2 mass%-70 mass%, and the range of 5 mass%-50 mass% is more preferable. If the concentration of the dye is less than 2% by mass, the dimming action may be reduced, and if it is more than 70% by mass, it may be difficult to obtain a material having good strength.

  On the other hand, as the pigment and the light scattering material, black pigments such as bronze powder, titanium black, various carbon blacks (channel black, furnace black, etc.); white pigments such as titanium oxide and silica, metal oxides such as calcium carbonate, Light scattering materials such as metal powders; color pigments such as phthalocyanine cyan pigments, benzidine yellow pigments, rhodamine magenta pigments; anthraquinone, azo, azo metal complexes, phthalocyanine, quinacridone, perylene Examples include various pigments and light-scattering materials such as those based on Indigo, isoindolinone, quinacridone, allylamide, and zinc sulfide.

  The pigment will be described in more detail. Examples of the yellow pigment include compounds typified by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. I. CI Pigment Yellow-12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168 are preferably used.

  Examples of magenta pigments include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. . I. Pigment Red-2, 3, 5, 6, 7, 23, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 144, 146, 166, 169, 177, 184, 185, 202 206, 220, 221, 254, etc. are preferably used.

  Examples of cyan pigments include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like. I. Pigment Blue-1, 7, 15, 15: 1, 15: 2, 15; 3, 15: 4, 60, 62, 66 and the like are preferably used.

  The particle size of the pigment and the light scattering material is preferably 0.001 μm to 1 μm, particularly preferably 0.01 μm to 0.5 μm, in terms of average particle size of primary particles. If the average particle size is less than 0.001 μm, the chargeable polymer gel particles may flow out, and if it exceeds 1 μm, the color development characteristics may be deteriorated.

  It is desirable that the pigment and the light scattering material are contained in the chargeable polymer gel particles as uniformly dispersed as possible and do not flow out of the chargeable polymer gel particles. By optimizing the crosslinking density of the gel particles, the pigments and light scattering materials are physically confined in the polymer network, and pigments with high electrical, ionic and other physical interactions with the charged polymer gel It is preferable to use a light scattering material, a pigment whose surface is chemically modified, or a light scattering material. For example, pigments or light scattering materials whose surfaces are chemically modified include those in which a group chemically bonded to a polymer gel such as an unsaturated group such as a vinyl group or an unpaired electron (radical) is introduced on the surface, or a polymer material And those whose surface is coated or encapsulated with a polymer or the like.

  The concentration of the pigment and light scattering material in the chargeable polymer gel particles is preferably in the range of 2% by mass to 70% by mass. When the amount is less than 2% by mass, the dimming action may be reduced, and when it is more than 70% by mass, it may be difficult to obtain a material having good strength.

As a method for obtaining the chargeable polymer gel particles containing such a light control material, a method in which the light control material is uniformly dispersed and mixed in the polymer before cross-linking, followed by cross-linking, and a polymer precursor at the time of polymerization. And a method of polymerizing by adding a light control material to the body monomer composition.
When adding a pigment or light scattering material during polymerization, it is also preferable to use a pigment or light scattering material having an unsaturated group or an unpaired electron (radical) as described above and chemically bond it to the polymer gel. Is done.
Further, the light modulating material is preferably dispersed as uniformly as possible in the chargeable polymer gel particles. In particular, it is preferable that the light control material polymer is uniformly dispersed in the chargeable polymer gel particles using a mechanical kneading method, a stirring method, or a dispersing agent.

  On the other hand, as described above, it is also possible to use the light modulating material as charged additive particles contained in the chargeable polymer gel particles. In this case, it is possible to charge the polymer gel by contact charging between the light control material contained in the chargeable polymer gel particles and the solvent, but the surface of the light control material should have a charge providing function. Is more preferable. As a method for imparting a charge imparting function to the surface of the light control material, the surface of the light control material is amino group, ammonium group, halogen group, hydroxyl group, carboxyl group, sulfonic acid group, phosphoric acid group, amide group, thiol group, etc. It is possible to introduce

Examples of the shape of the chargeable polymer gel particles include spheres, cubes, ellipsoids, polyhedra, porous bodies, fibers, stars, needles, hollows, rings, and the like. Among these, the spherical shape is particularly preferable from the viewpoint of isotropically allowing the charged polymer gel particles to expand and contract.
The preferred size of the chargeable polymer gel particle particles is in the range of 0.1 μm to 200 μm, more preferably in the range of 1 μm to 100 μm in terms of the average particle size in the state that does not contain the liquid. When the average particle size is less than 0.1 μm, it may be difficult to handle the particles, or excellent optical characteristics may not be obtained. On the other hand, when the average particle diameter exceeds 100 μm, the migration speed may be slow.

  These chargeable polymer gel particles are a method of pulverizing a polymer gel by a physical pulverization method, a method of cross-linking a polymer before crosslinking into particles by a physical pulverization method or a chemical pulverization method, and forming a gel, Alternatively, it can be produced by a general method such as a particle polymerization method such as an emulsion polymerization method, a suspension polymerization method or a dispersion polymerization method.

  The amount of absorption (liquid absorption) of the electrical insulating liquid described later due to the expansion of the chargeable polymer gel particles preferably absorbs 2 to 200 g of the electrically insulating liquid per 1 g of the contracted charged polymer gel particles. . When the liquid absorption amount is less than 2 g, there may be a case where a sufficient change in optical characteristics cannot be caused. When the liquid absorption amount exceeds 200 g, the concentration of the light control material in the chargeable polymer gel particles May decrease, and the dimming contrast may decrease.

Next, the electrical insulating liquid will be described.
In the present invention, the electrically insulating liquid, the volume resistivity refers to a liquid at 10 ³ [Omega] cm or more, the volume resistivity is preferably from 10 ⁴ Ωcm~10 ¹⁹ Ωcm, at 10 ⁶ to 10 ¹⁹ [Omega] cm More preferably. By setting the volume resistance value to 10 ³ Ωcm or more, the generation of bubbles due to the electrolysis of the liquid due to the electrode reaction is suppressed, and the dimming characteristics are not impaired every time energization is imparted, giving excellent repeated stability. can do. From this point of view, it is necessary to use an electrically insulating liquid having a volume resistance of 10 ³ Ωcm or more as the liquid. In addition, an acid, an alkali, a salt, a dispersion stabilizer, a stabilizer for the purpose of preventing oxidation or ultraviolet absorption, an antibacterial agent, an antiseptic, and the like can be added to the electrical insulating liquid. However, it is necessary to make the volume resistance value of the electrically insulating liquid after addition of the stabilizer, the antibacterial agent, the preservative, etc. 10 ³ Ωcm or more.

  Examples of the electrical insulating liquid include hexane, cyclohexane, toluene, xylene, decane, hexadecane, kerosene, paraffin, isoparaffin, silicone oil, dichloroethylene, trichloroethylene, perchloroethylene, high-purity petroleum, ethylene glycol, alcohols, ether , Esters, dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, 2-pyrrolidone, N-methylformamide, acetonitrile, tetrahydrofuran, propylene carbonate, ethylene carbonate, benzine, diisopropylnaphthalene, olive oil, isopropanol, trichlorotrifluoro Ethane, tetrachloroethane, dibromotetrafluoroethane, etc. and their mixtures can be used .

  Furthermore, colorants such as various dyes and pigments may be added to color the electrical insulating liquid. Examples of such pigments and dyes that are colorants include various compounds similar to the pigments and dyes used in the above-described light control materials. In this case, it is preferable that the chargeable polymer gel particles have a property that can absorb only the solvent in the electrically insulating liquid and does not absorb the coloring material.

  As a preferable combination of the chargeable polymer gel particles and the electrically insulating liquid, the chargeable polymer gel particles include a cross-linked product of a salt of poly (meth) acrylic acid and (meth) acrylamide, and the electrically insulating liquid. A combination of dimethylformamide, ethylene carbonate and propylene carbonate, a cross-linked product of a salt of poly (meth) acrylic acid and (meth) acrylamide, and two or more solvents of the group consisting of dimethylformamide, ethylene carbonate and propylene carbonate A combination with a mixed solvent mixed, or a combination of N-isopropylacrylamide cross-linked as chargeable polymer gel particles and a combination of dimethylformamide or dimethylsulfoxide as an electrically insulating liquid, among which chargeable polymer gel particle And crosslinked product of poly (meth) and salts of acrylic acid and (meth) acrylamide and a combination of a mixed solvent of dimethylformamide and propylene carbonate as an electrical insulating liquid is more preferred.

In the optical element of the present invention, as described above, the chargeable polymer gel particles are immobilized on the electrode so that they can be stably reversibly expanded and contracted without applying electrophoresis by applying an electric field. It is preferable that The immobilization may be performed on all the electrodes when there are a plurality of electrodes.
Such chargeable polymer gel particles can be immobilized by using various bifunctional compounds and adhesives, or by physical means.
For example, it is possible to covalently bond by reacting the functional group of the chargeable polymer gel particles by introducing a functional group by treating the electrode substrate with a reactive silane coupling material in advance. In addition, there are a method of fixing with various polyfunctional compounds and adhesives, and a method of physically fixing the charged polymer gel particles by three-dimensionally processing the substrate. In fixing the chargeable polymer gel particles, if the chargeable polymer gel particles are brought into close contact with the electrode substrate described later, the response characteristics may deteriorate. A method of bonding the chargeable polymer gel particles to the electrode substrate by means of three-dimensionally processing the particles and bonding them to the convex portions or a long chain compound is also preferably applied.

An electrode substrate for applying an electric field to the chargeable polymer gel is usually produced by forming a current-carrying member on the substrate member.
Examples of the substrate member include polyester, polyimide, polymethyl methacrylate, polystyrene, polypropylene, polyethylene, polyamide, nylon, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyether sulfone, silicone resin, polyacetal resin, fluorine resin, and cellulose derivative. Polymer films such as polyolefin, plate substrates, glass substrates, metal substrates, ceramic substrates, and other inorganic substrates are preferably used.

On the other hand, as the energizing member formed on the substrate member, a member in which a metal oxide layer represented by tin oxide-indium oxide (ITO), tin oxide, zinc oxide or the like is formed is preferably used.
When the optical element of the present invention is used as a transmissive display element (second embodiment), a transparent electrode having a light transmittance of at least 50% is preferably used.
Furthermore, when the optical element of the present invention is used as a reflective optical element (the first embodiment), the current-carrying member is represented by tin oxide-indium oxide (ITO), tin oxide, zinc oxide, or the like. In addition to the metal oxide layer, a conductive polymer or a metal layer represented by carbon, copper, aluminum, gold, silver, nickel, platinum, or the like can be preferably used.

Various thicknesses and sizes of the current-carrying member can be used depending on a desired display element, and there is no particular limitation, but a preferable thickness range is 10 to 20 nm.
Depending on the use of the display element, a driving switching element such as a wiring, a thin film transistor, a diode having a metal / insulating layer / metal structure, a variable capacitor, or a ferroelectric may be formed on the electrode substrate.
In general, when displaying an image as a display application, in a configuration having a patterned electrode, it can be realized by energizing a desired pattern and changing the volume of the polymer gel on the pattern. Further, color display can also be realized by fixing a plurality of different color polymer gels on each pattern and selectively energizing various patterns.

  Moreover, it is preferable to perform a surface treatment on the surface of the electrode substrate so that the chargeable polymer gel cannot be fixed except in a region where the chargeable polymer gel particles are fixed in a contracted state. The surface treatment has a low adhesive property with the chargeable polymer gel particles, and does not form a chemical bond (hydrogen bond, ionic bond, covalent bond) with the chargeable polymer gel. In this method, the surface treatment is performed with a region or material treated so as to have low interaction and affinity. Specifically, a method for forming a polymer layer having a fluorinated alkyl group or a siloxane group, an alkyl silane coupling agent, a fluorinated alkyl silane coupling agent, an alkyl thiol, a fluorinated alkyl thiol, etc. The method of using and processing is mentioned.

  Examples of the polymer having an alkyl fluoride group include polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. A fluorine-type resin is mentioned. Examples of the polymer having a siloxane group include silicone resins such as dimethyl silicone, methyl phenyl silicone, amino modified body of epoxy, epoxy modified body, carboxyl modified body, methacryl modified body, phenol modified body, and alkyl modified body. It is done. The surface treatment includes a method of treating the surface of the electrode substrate by dissolving or dispersing these polymers in a solvent and immersing the electrode substrate.

Examples of the partial processing method on the electrode substrate include a method using a processing technique such as a sputtering method, a coating method, a printing method, a sol-gel method, a virsol method, a chemical vapor deposition method, a vacuum deposition method, and an ion plating method. Can be mentioned.
In addition, as the material itself has a low adhesive property with the chargeable polymer gel particles, urea resin, epoxy resin, polyvinyl chloride, polyethyl methacrylate, polyvinyl acetate, nylon, polyethylene terephthalate, polyvinyl alcohol, Examples include polystyrene, polyethylene, and polypropylene.

The optical element of the present invention preferably has a configuration in which the chargeable polymer gel particles and the electrically insulating liquid (light control layer) are sealed. Since the light control layer is hermetically sealed, the light control layer does not come into contact with the outside air, and deterioration can be prevented. Such a configuration can be performed by, for example, resin-sealing the light control layer sandwiched between the electrodes, or disposing the light control layer between the electrodes formed into cells.
Further, various layers may be formed on the optical element of the present invention. For example, a protective layer for the purpose of protecting the optical element, an antifouling layer, an ultraviolet absorbing layer, an antistatic layer, a light reflecting layer, a dielectric layer, a colored layer such as a color filter, and the like can be mentioned.

Hereinafter, the present invention will be specifically described with reference to examples of the optical element, but the present invention is not limited to the following examples.
<Example 1>
(Preparation of chargeable polymer gel particles)
Charged polymer gel particles containing the pigment were produced by reverse phase suspension polymerization as shown below.
N-isopropylacrylamide 0.79 g, acrylic acid 0.2 g, triethylamine 0.43 g, distilled water 2.28 g, white pigment dispersion aqueous solution 2.25 g, methylenebisacrylamide 2.5 mg as a crosslinking agent, and ammonium persulfate 0.020 g Was added to 0.5 g of pure water and mixed by stirring to prepare an aqueous solution A. These operations were performed in a nitrogen atmosphere.
Next, an aqueous solution A in which 1.5 g of a sorbitol surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Sorgen 50) as a dispersion stabilizer was dissolved in 300 g of cyclohexane in a beaker and nitrogen-substituted was added. It was emulsified by high-speed stirring at 1400 rpm for 10 minutes.
Further, the temperature of the reaction system was adjusted to 25 °, and while stirring the solution, a 50% cyclohexane solution of N, N, N ′, N′-tetramethylethylenediamine was added to perform polymerization. After the polymerization, the produced polymer gel particles were collected and washed with methanol to obtain white chargeable polymer gel particles.
When some gel particles were replaced with DMF (dimethylformamide), the average particle size was 100 μm.

(Production of optical elements)
The white charged polymer gel produced was swollen with a methanol solution to obtain a polymer gel dispersion solution.
Next, as a transparent substrate, a transparent glass electrode (manufactured by Asahi Glass Co., Ltd.) with a tin oxide film of 50 mm × 50 mm and a thickness of 3 mm was used. The transparent substrate was subjected to surface cleaning with acetone and a 2N-NaOH aqueous solution. Further, the transparent substrate subjected to surface cleaning was immersed in a solution prepared by adding 4 ml of γ-aminopropyltriethoxysilane (fixing agent) to 200 ml of a 95% ethanol aqueous solution with stirring. The soaked transparent substrate was taken out and lightly washed with ethanol, and then left in an oven at 110 ° for 30 minutes to cure the silane layer and obtain an electrode substrate whose entire surface was treated with a fixing agent.

The polymer gel dispersion solution was uniformly applied on the electrode substrate whose entire surface was surface-treated with a fixing agent, and then immersed for about 10 hours to perform an immobilization treatment. The white chargeable polymer gel particles were uniformly fixed on the entire surface of the element substrate treated with the fixing agent.
Furthermore, a glass with a tin oxide film of 50 mm × 50 mm and a thickness of 3 mm is used as a counter substrate, and a resin spacer of 130 μm is placed on the surface inwardly facing the electrode surface, and the outer peripheral portion is heated except for some solution injection openings. Sealed with adhesive. After injecting DMF (volume resistivity 10 ⁶ Ωcm) colored with oil-based black ink as a swelling liquid (electrically insulating liquid) of colored polymer gel into the cell, the opening is sealed and an optical element (light control cell) Was made.

(Evaluation)
When the obtained optical element was observed from the normal direction of the electrode substrate (counter substrate), it was initially observed as black, which is the color of the colored electrically insulating liquid. Next, when the electrode side on which the white chargeable polymer gel particles are fixed is grounded and a DC voltage of 10 V is applied to the counter electrode, the white chargeable polymer gel particles swell (expand), It was observed that the optical element changed from black to white when pressed against the counter electrode surface. Conversely, when a DC voltage of −10 V was applied to the counter electrode, the white chargeable polymer gel particles contracted, and the optical element returned to the initial black color again. The contrast ratio obtained from the reflectance was 30 or more, and the visibility was excellent. Furthermore, application of a voltage of ± 10 V to the counter electrode was repeated 1,000,000 times, but it was confirmed that no bubbles were generated and the contrast was not deteriorated and was extremely stable. The contrast of the optical element was obtained by measuring the optical density with a spectrophotometer.

<Example 2>
(Preparation of transparent chargeable polymer gel particles)
Transparent chargeable polymer gel particles were prepared by reverse phase suspension polymerization as shown below.
Add 0.79 g of N-isopropylacrylamide, 0.2 g of acrylic acid, 0.43 g of triethylamine, 4.38 g of distilled water, 2.5 mg of methylenebisacrylamide as a crosslinking agent, and 0.020 g of ammonium persulfate to 0.5 g of pure water. An aqueous solution B mixed with stirring was prepared. These operations were performed in a nitrogen atmosphere.
Next, an aqueous solution B in which 1.5 g of a sorbitol surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Sorgen 50) as a dispersion stabilizer was dissolved in 300 g of cyclohexane in a beaker and nitrogen-substituted was added, and a rotary stirring blade was added. It was emulsified by high-speed stirring at 1400 rpm for 10 minutes.
Next, the temperature of the reaction system was adjusted to 25 °, and while stirring the solution, a 50% cyclohexane solution of N, N, N ′, N′-tetramethylethylenediamine was added to perform polymerization. After the polymerization, the produced transparent chargeable polymer gel particles were collected and washed with methanol.
When a part of the gel particles was replaced with DMF, the average particle size was 100 μm.

(Production of optical elements)
The produced transparent chargeable polymer gel particles were swollen with a methanol solution to obtain a polymer gel dispersion solution. Next, in the same manner as in Example 1, transparent chargeable polymer gel particles were immobilized on a glass with a tin oxide film of 50 mm × 50 mm and a thickness of 3 mm. A glass electrode with a tin oxide film of the same size was used as a counter substrate, a 130 μm resin spacer was placed inwardly on the electrode surface, and the outer peripheral portion was sealed with a thermal adhesive except for some solution injection openings. After injecting DMF (volume resistivity 10 ⁶ Ωcm) colored with oil-based black ink as a swelling liquid (liquid) of colored polymer gel into the cell, the opening is sealed to produce a light control element (light control cell). did.

(Evaluation)
When the obtained optical element was observed from the normal direction of the electrode substrate, it was initially observed as black, which is the color of the colored electrically insulating liquid. When the transmittance of the optical element was measured at this time, the transmittance was about 3% on the average in the visible light region. Next, when the electrode side on which the transparent chargeable polymer gel particles are fixed is grounded and a DC voltage of 10 V is applied to the counter electrode, the transparent chargeable polymer gel particles swell and form on the surface of the counter electrode. By being pressed, light was transmitted through the portion where the transparent chargeable polymer gel particles were pressed, and the amount of transmitted light increased. At this time, the transmittance of the optical element was 65%, and it was confirmed that a large transmittance change width was obtained. Conversely, when a DC voltage of −10 V was applied to the counter electrode side, the transparent chargeable polymer gel contracted and the optical element returned to the initial black color again. Application of a voltage of ± 10 V was repeated 1 million times, but no bubbles were generated, the transmittance change width was not changed, and it was confirmed that it was extremely stable. The transmittance of the optical element was measured with a spectrophotometer.

<Example 3>
(Preparation of chargeable polymer gel particles)
Charged (nonionic) polymer gel particles that swell and contract by an electric field were prepared by reverse phase suspension polymerization as shown below.
10 g of N-isopropylacrylamide as the main monomer, 0.1 g of methylenebisacrylamide as the cross-linking agent, 20 g of distilled water, 0.1 g of ammonium persulfate, and blue pigment (primary particle 0.1 μm) as the pigment (charging agent) Dainippon Ink Chemical Co., Ltd .: 8.0 g of microencapsulated pigment, MC Blue 182-E) was added, and an aqueous solution C mixed with stirring was prepared. The above operation was performed under nitrogen.
Next, a solution obtained by dissolving 1.0 g of a sorbitol surfactant (Daiichi Kogyo Seiyaku: Sorgen 50) in 200 ml of cyclohexane is added to a container purged with nitrogen, and the previously prepared aqueous solution C is added to the solution. The mixture was emulsified by high-speed stirring using a type stirrer. After emulsification, the temperature of the reaction system was adjusted to 20 ° C., and a 50% aqueous solution of tetramethylethylenediamine was added thereto while stirring the solution to carry out polymerization. After the polymerization, the produced colored polymer gel particles were collected and washed with pure water.
Thereafter, water in the colored polymer gel particles was removed by freeze drying. After the distillation, the charged polymer gel particles (colored polymer gel particles) were swollen by adding dimethylformamide (DMF) that had been stored after adding molecular sieves to the dried colored polymer gel.

(Production of optical elements)
The colored polymer gel particles prepared above were immobilized on an electrode substrate with tin oxide having a size of 50 mm × 50 mm by the following method.
A binder layer for fixing the chargeable polymer gel on the electrode was formed by applying a silane coupling agent (3-Glycoxypropyltrimethylsilane) solution to the electrode surface, allowing the electrode surface to react, and washing.
Next, a solution comprising the previously prepared chargeable polymer gel particles and DMF is prepared, and this is brought into contact with the electrode surface and heated to chemically chemistry the reactive silane coupling part on the glass surface and the gel particles. The reaction was immobilized. Further, an electrode substrate with tin oxide having a size of 50 mm × 50 mm is used as a counter substrate, and a 500 μm resin spacer is placed on the surface thereof inwardly facing the electrode surface, and the outer peripheral portion is a thermal adhesive except for some solution injection openings. Sealed with. After injecting only DMF (volume resistivity 10 ⁶ Ωcm) as a swelling liquid (liquid) of the chargeable polymer gel into the cell, the opening was sealed to produce an optical element (light control cell). In addition, when the swelling liquid (liquid) in a cell was extract | collected and the volume resistivity was measured, the volume resistance value derived from DMF was shown.

(Evaluation)
The obtained optical element was found to change the volume of the colored polymer gel particles by applying a DC voltage of 35 V between the opposed electrodes. When the electrode side on which the chargeable polymer gel particles are immobilized becomes the cathode, the chargeable polymer gel particles swelled. Conversely, when the electrode side on which the chargeable polymer gel particles are immobilized becomes the anode, the chargeable polymer gel particles contracted. Thereby, it turned out that a coloring polymer gel particle swells and shrinks according to an electric field. The contrast ratio obtained from the reflectance was 30 or more, and the visibility was excellent. On the other hand, the repetition by reversing the polarity of the 35V applied voltage was carried out 1 million times, but the generation of bubbles was not confirmed, and it was confirmed that it was extremely stable.

<Example 4>
(Production of charging agent polymer gel particles)
Charger polymer gel particles that swell and contract by an electric field were prepared by reverse phase suspension polymerization as shown below. 10 g of N-isopropylacrylamide as the main monomer, 0.1 g of methylenebisacrylamide as the cross-linking agent, 20 g of distilled water, 0.1 g of ammonium persulfate, and blue pigment (primary particle 0.1 μm) as the pigment (charging agent) Dainippon Ink Chemical Co., Ltd .: 8.0 g of microencapsulated pigment, MC Blue 182-E) was added, and an aqueous solution D mixed by stirring was prepared. The above operation was performed under nitrogen. A solution obtained by dissolving 1.0 g of a sorpitol surfactant (Daiichi Kogyo Seiyaku: Sorgen 50) in 200 ml of cyclohexane is added to a container purged with nitrogen, and the previously prepared aqueous solution D is added thereto. Was emulsified by stirring at high speed. After emulsification, the temperature of the reaction system was adjusted to 20 ° C., and a 50% aqueous solution of tetramethylethylenediamine was added thereto while stirring the solution to carry out polymerization. After the polymerization, the produced charging agent polymer gel particles were collected and washed with pure water.
Thereafter, water in the colored polymer gel was removed by freeze drying. After the distillation, the charged polymer gel particles (colored polymer gel particles) were swelled by adding dimethylformamide (DMF) that had been preserved by adding molecular sieves to the dried colored polymer gel.

(Production of optical elements)
On the electrode substrate with tin oxide having a size of 50 mm × 50 mm, the prepared colored polymer gel particles were fixed by the following method. A binder layer for fixing the colored polymer gel on the electrode was formed by applying a silane coupling agent (3-Glycoxypropyltrimethylsilane) solution to the electrode surface, causing the electrode surface to react, and washing.
Next, the previously prepared solution of colored polymer gel particles and water is prepared, and this is brought into contact with the electrode surface and heated to cause a chemical reaction between the reactive silane coupling part on the glass surface and the gel particles. Allowed to immobilize. Further, an electrode substrate with tin oxide having a size of 50 mm × 50 mm is used as a counter substrate, and a 500 μm resin spacer is placed on the surface thereof inwardly facing the electrode surface, and the outer peripheral portion is a thermal adhesive except for some solution injection openings. Sealed with. After injecting only ion-exchanged water (volume resistivity 10 ⁵ Ωcm) as a swelling liquid (liquid) of the colored polymer gel into the cell, the opening was sealed to produce a light control element (light control cell). In addition, when the swelling liquid (liquid) in a cell was extract | collected and the volume resistivity was measured, the volume resistance value derived from ion-exchange water was shown.

(Evaluation)
The obtained optical element was found to change the volume of the colored polymer gel particles by applying a DC voltage of 5 V between the opposed electrodes. When the electrode on which the colored polymer gel particles were immobilized became the cathode, the colored polymer gel particles swelled, and conversely, when the electrode became the anode, it contracted. Thereby, it turned out that a coloring polymer gel particle swells and shrinks according to an electric field. The contrast ratio obtained from the reflectance was 30 or more, and the visibility was excellent. On the other hand, the repetition by the reversal of the polarity of the 5V applied voltage was carried out 1 million times, but the generation of bubbles was not confirmed, and it was confirmed that it was extremely stable.

<Comparative Example 1>
(Manufacture of optical elements)
0.75 g of acrylamide, 0.20 g of sodium acrylate, 0.02 g of N, N-methylenebisacrylamide and 50 μl of tetramethylethylenediamine were added and dissolved in 14 ml of water to prepare a monomer solution. Separately, 20 mg of ammonium persulfate is dissolved in 1 ml of water, mixed with the monomer solution, immediately poured into a mixed solvent of 100 ml of toluene and 1 ml of sorbitan trioleate, and vigorously stirred under a nitrogen atmosphere.
After completion of the polymerization, the produced chargeable polymer gel particles are first thoroughly washed with hexane and then washed with acetone to be agglomerated. Further, washing is alternately repeated with 50% acetone aqueous solution and 70% acetone aqueous solution, and finally dispersed in 50% acetone aqueous solution.

A glass plate (50 mm × 50 mm) on which a semi-transparent film of platinum (15 nm) is deposited in an appropriate pattern in this dispersion of chargeable polymer gel particles is used as an anode, and a nickel plate is used as a cathode. Was applied to agglomerate the chargeable polymer gel particles on the platinum electrode.
The platinum electrode on which the chargeable polymer gel particles are aggregated is used as a cathode, a 20 μm Mylar film is sandwiched, and a glass plate (50 mm × 50 mm) having a 200 nm-thick ITO film formed on the entire surface by sputtering is opposed to the anode.
Using a ball mill, the optical element was filled with 60% acetone aqueous solution (volume resistivity 10 ² Ωcm) in which brilliant carmine 3B (CI Pigment Red 60; CI 16015-Lake) was dispersed using a ball mill. Manufactured. The transmittance of this optical element was measured and found to be 60%.

(Display and modulation)
A voltage was gradually increased from 0.8 V using a platinum translucent electrode of this optical element as a cathode and an ITO electrode as an anode. When the applied voltage exceeded 1.5 V, the chargeable polymer gel particles interposed between the applied electrodes were swollen and the transmittance was changed to 80%. At the same time, the generation of bubbles was confirmed by electrolysis of the aqueous solution.
When the switch was turned off to 0 V, the charged polymer gel particles contracted and returned to the color of the 60% acetone aqueous solution.
Further, when the voltage was repeatedly applied while changing the polarity of the applied voltage, the change in the transmittance change could not be confirmed when the voltage was repeated about 10 times.

<Comparative example 2>
(Preparation of chargeable polymer gel particles)
Nonionic polymer gel particles that swell and contract by an electric field were prepared by reverse phase suspension polymerization as shown below. 10 g of N-isopropylacrylamide as the main monomer, 0.1 g of methylenebisacrylamide as the cross-linking agent, 20 g of distilled water, 0.1 g of ammonium persulfate, and blue pigment (primary particle 0.1 μm) as the pigment (charging agent) Dainippon Ink & Chemicals, Inc .: Microencapsulated pigment, MC Blue 182-E) (8.0 g) was added, and an aqueous solution E mixed with stirring was prepared. The above operation was performed under nitrogen. A solution obtained by dissolving 1.0 g of a sorpitol surfactant (Daiichi Kogyo Seiyaku: Sorgen 50) in 200 ml of cyclohexane is added to a container purged with nitrogen, and the previously prepared aqueous solution E is added thereto. Was emulsified by stirring at high speed. After emulsification, the temperature of the reaction system was adjusted to 20 ° C., and a 50% aqueous solution of tetramethylethylenediamine was added thereto while stirring the solution to carry out polymerization. After the polymerization, the produced colored polymer gel was recovered and washed with pure water.
Thereafter, water in the chargeable polymer gel particles was removed by freeze drying. After the distillation, the charged polymer gel particles (colored polymer gel particles) were swollen by adding dimethylformamide (DMF) that had been stored after adding molecular sieves to the dried colored polymer gel.

(Production of optical elements)
On the electrode substrate with tin oxide having a size of 50 mm × 50 mm, the chargeable polymer gel particles prepared above were immobilized by the following method. A binder layer for immobilizing the chargeable polymer gel particles on the electrode was formed by applying a silane coupling agent (3-Glycidopropyltrimethylsilane) solution to the electrode surface, allowing the electrode surface to react, and washing.
Next, the previously prepared solution comprising the chargeable polymer gel particles and water is prepared, and this is brought into contact with the electrode surface and heated to heat the reactive silane coupling part on the glass surface and the chargeable polymer gel. The particles were immobilized by chemical reaction. Further, an electrode substrate with tin oxide having a size of 50 mm × 50 mm is used as a counter substrate, and a 500 μm resin spacer is placed on the surface thereof inwardly facing the electrode surface, and the outer peripheral portion is a thermal adhesive except for some solution injection openings. Sealed with. After injecting only 0.1 mol / l potassium hydroxide (volume resistivity 10 ⁻² Ωcm) as a swelling liquid (liquid) of the colored polymer gel into the cell, the opening is sealed and an optical element (light control cell) Was made. In addition, when the swelling liquid (liquid) in a cell was extract | collected and the volume resistivity was measured, the volume resistance value derived from potassium hydroxide was shown.

(Evaluation)
In the obtained optical element, when a direct current voltage of 35 V is applied between the electrodes facing each other, bubbles are generated violently due to the electrode reaction of the swelling solvent water, and liquid leakage occurs from the sealed portion due to the generated bubbles. It was. At this time, no volume change was observed in the chargeable polymer gel particles.

(A) It is a schematic sectional drawing of the state which the chargeable polymer gel particle in 1st embodiment of the optical element of this invention contracted. (B) It is a schematic sectional drawing of the state which the chargeable polymer gel particle expanded in 1st embodiment of the optical element of this invention. (A) It is the external view seen from the normal line direction of the electrode substrate 2 of the state with which the chargeable polymer gel particle in the 1st embodiment of the optical element of this invention contracted. (B) It is the external view seen from the normal line direction of the electrode substrate 2 of the state which the chargeable polymer gel particle in the 1st embodiment of the optical element of this invention expanded. It is a schematic sectional drawing of the state which the chargeable polymer gel particle in 1st embodiment of the optical element of this invention contracted. It is the external view seen from the normal line direction of the electrode substrate 2 in the state which the chargeable polymer gel particle in the 1st embodiment of the optical element of this invention contracted. (A) It is a schematic sectional drawing of the state to which the chargeable polymer gel particle in 2nd embodiment of the optical element of this invention contracted. (B) It is a schematic sectional drawing of the state which the chargeable polymer gel particle in the second embodiment of the optical element of this invention expanded. (A) It is the external view seen from the normal line direction of the electrode substrate 2 of the state with which the chargeable polymer gel particle in the second embodiment of the optical element of this invention contracted. (B) It is the external view seen from the normal line direction of the electrode substrate 2 of the state which the chargeable polymer gel particle in the 2nd embodiment of the optical element of this invention expanded.

Explanation of symbols

2, 4 Electrode substrate 6 Colored electrically insulating liquid 8 Chargeable polymer gel particle 8 'Transparent chargeable polymer gel particle

Claims (7)

An electrically insulating liquid having a volume resistivity of 10 ³ Ωcm or more, a colored electrically insulating liquid, and a charged polymer gel particle that absorbs and releases the electrically insulating liquid by application of an electric field, and expands and contracts; An optical element comprising at least a pair of electrode substrates that sandwich the substrate.   The optical element according to claim 1, wherein the chargeable polymer gel particles are fixed to at least one of the pair of electrode substrates. A distance L between a pair of electrode substrates sandwiching the electrically insulating liquid and the chargeable polymer gel particles, an average particle diameter d ₀ of the chargeable polymer gel particles when contracted, and a high chargeability when expanded. The optical element according to claim 1, wherein the average particle diameter d of the molecular gel particles satisfies the following relationship.
d ₀ <L <d   The optical element according to claim 1, wherein the chargeable polymer gel particles contain a light control material.   The optical element according to claim 1, wherein the chargeable polymer gel particles are ionic polymer gel particles.   The optical element according to claim 1, wherein the chargeable polymer gel particles are ionic polymer gel particles containing a charge agent.   The optical element according to claim 1, wherein the chargeable polymer gel particles are nonionic polymer gel particles containing a charging agent.

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