JP2005004185A - Dispersion liquid for electrophoresis display, and display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispersion liquid for electrophoresis display wherein dispersion stability of pigment particles is heightened and the pigment particles have excellent electrophoretic properties and high response speed even when application voltage is low and to provide a device for electrophoresis display using the dispersion liquid. <P>SOLUTION: The dispersion liquid for electrophoresis display containing an electrically insulating solvent, a pigment and a polymer dispersant contains, as the dispersant, a compound having at least a bonding chain represented by general formula (A) in its molecule (in formula, X denotes an oxygen atom or a nitrogen atom which is represented by N(R<SP>1</SP>) and may be substituted, wherein R<SP>1</SP>denotes a hydrogen atom or an alkyl group). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophoretic display dispersion capable of changing a visual state by moving colored particles in a dispersion medium by applying an electric field to the dispersion medium containing colored particles such as pigments, and an electric power using the dispersion. The present invention relates to an electrophoretic display device.

Conventionally, many electrophoretic display devices using an electrophoretic effect have been proposed. However, they are usually colored between a pair of electrodes that are two transparent substrates at least one of which is opposed to each other via a spacer. A dispersion liquid in which particles are dispersed is enclosed, and an electric field is applied between the electrodes to move the colored particles to form an image, thereby displaying a desired image.
In such an electrophoretic display device, by controlling the direction of application of an electric field, a desired display is performed by moving and moving to the transparent electrode side according to the polarity of colored particles, for example, pigment particles. In order to disperse pigment particles stably in an insulating and low dielectric constant solvent and to move pigment particles to a desired position, it is a big problem to reduce the applied voltage between electrodes.

Among these problems, as a method for improving dispersion stability, for example, it has been proposed to coat the surface of pigment particles with an ethylene copolymer resin (Japanese Patent Laid-Open No. 62-183439). According to the embodiment described in this publication, when a DC current of 10 V is applied between the anode and the cathode of the display element, migration of particles in the display element cell occurs, and white-blue display is promptly performed. It has been shown.
However, it is difficult to coat the entire particles with a resin while keeping the fine pigment particles in the shape of the primary particle size. In the above publication, the coating of the particles is realized by performing a flushing process. However, this process is industrially disadvantageous because the manufacturing process becomes long and the process temperature is high.

In addition, it has also been proposed to improve the dispersion stability of a pigment by adding a high molecular weight surfactant as a pigment dispersant to the system (Japanese Patent Laid-Open No. 2001-125147). There is a need for improvement.
On the other hand, to improve electrophoretic properties, it has been proposed to add a specific compound as a charge control agent to the pigment dispersion (Japanese Patent Laid-Open No. 11-119704). However, in these conventional techniques, it is necessary to apply a voltage of 50 V to 1000 V between the electrodes during electrophoresis, and it was not possible to drive at a low voltage.
JP-A-62-183439 JP 2001-125147 A Japanese Patent Laid-Open No. 11-119704

  The present invention improves the dispersion stability of pigment particles in a dispersion for electrophoretic display, and provides a dispersion having excellent electrophoretic properties of pigment particles even at a low applied voltage, and having a fast response speed. An object of the present invention is to provide an electrophoretic display device.

As a result of intensive studies on the composition of the dispersion liquid to achieve such an object, the present inventors have found that a compound having a bonding chain represented by the general formula (A) in the molecule in the dispersion liquid for electrophoretic display. It has been found that the dispersion stability and electrophoretic properties of the pigment can be improved by the inclusion as a dispersant.
That is, the gist of the present invention is a compound having at least a bonding chain represented by the following general formula (A) in the molecule as a dispersant in an electrophoretic display dispersion containing an electrically insulating solvent, a pigment and a dispersant. In a dispersion for electrophoretic display, comprising:

（式中、Ｘは酸素原子またはＮ（Ｒ¹）で示される置換されていてもよい窒素原子を表し、Ｒ¹は水素原子またはアルキル基を表す。）
本発明の他の要旨は、基板の片側に電極を設けた一対の表示用基材を、スペーサーを介して電極面を対向配置させて空間を形成し、その空間に上記電気泳動表示用分散液を充填し、且つ該一対の表示用基材の少なくとも一方の基材が透明基板の片側に透明電極を設けてなるものであることを特徴とする電気泳動表示装置に存する。

(In the formula, X represents an oxygen atom or an optionally substituted nitrogen atom represented by N (R ¹ ), and R ¹ represents a hydrogen atom or an alkyl group.)
Another gist of the present invention is that a pair of base materials for display provided with electrodes on one side of a substrate are arranged so that the electrode surfaces face each other via a spacer to form a space, and the electrophoretic display dispersion liquid in the space And at least one base material of the pair of display base materials is provided with a transparent electrode on one side of a transparent substrate.

  By using the dispersion liquid for electrophoretic display containing the dispersant having the specific bonding chain in the molecule of the present invention, the dispersion stability and electrophoretic property of the pigment are improved, and it is driven at a low voltage (screen display). A possible electrophoretic display device is provided.

The dispersion for electrophoretic display of the present invention basically contains an electrically insulating solvent, a pigment, and a polymer dispersant as constituent components, and the dispersant is a bond represented by the general formula (A). It contains a compound having a chain in the molecule, and the electrically insulating solvent contains an ester solvent or an ether solvent.
<Pigment>
The pigment particles as the colored particles used in the dispersion liquid of the present invention are not particularly limited, and can be appropriately selected and used from various pigment particles conventionally used in display dispersion liquids for electrophoresis. As the pigment particles, any of a pigment having a charge, a pigment capable of imparting a charge, or a pigment having no charge (that is, no electrophoresis) can be used. For example, a general pigment, Examples include lake pigments and pigments coated with a resin. These pigments may be organic substances or inorganic substances, may be light absorbing or light emitting, and may be light scattering or light reflecting. . In selecting the pigment, it is necessary to select a combination that is hardly soluble or insoluble in the solvent (dispersion medium) used in the dispersion.

  The pigment used in the present invention is selected from known pigments corresponding to a desired display color such as white, black, cyan, magenta, and yellow. Specifically, for example, metal oxides such as silica, titanium oxide, and alumina; black colorants such as carbon black, aniline black, furnace black, lamp black, and titanium black: phthalocyanine blue, methylene blue, Victoria blue, methyl Cyan colorants such as violet, aniline blue, ultramarine blue; magenta colorants such as rhodamine 6G lake, dimethylquinacridone, watching red, rose bengal, rhodamine B, alizarin lake; chrome yellow, benzidine yellow, hansa yellow, naphthol And yellow colorants such as yellow, molybdenum orange, quinoline yellow, and tartrazine. These pigments can be used alone or in combination. Various color pigments described in US Pat. No. 6,300,932 can also be used.

  In addition, composite particles obtained by combining the pigment with a resin can also be used. Specifically, for example, the pigment particles may be encapsulated by being coated with a resin, or fine pigment particles uniformly dispersed in a resin may be pulverized to a desired particle size. . Examples of the resin that can be used for the composite include polystyrene, polyethylene, polypropylene, phenol resin, ethylene-vinyl acetate copolymer (Du Pont (Elvax resins)), polyester, polyacrylate, polymethacrylate, and ethylene. -Acrylic acid or methacrylic acid copolymer (Nucrel Resins from Du Pont, Inc., Primacor Resins from Dow Chemical), acrylic copolymers and terpolymers (Elvacite Resins from Du Pont) And polymethyl methacrylate. Substances useful for homopolymer / pigment phase separation in high shear melt include, but are not limited to, the following: For example, polyethylene, polypropylene, polymethyl methacrylate, polyisobutyl methacrylate, polystyrene, polybutadiene, polyisoprene, polyisobutylene, polylauryl methacrylate, polystearyl methacrylate, polyisobornyl methacrylate, poly t-butyl methacrylate, polyethyl methacrylate, polymethyl Examples thereof include acrylate, polyethyl acrylate, polyacrylonitrile, and copolymers of two or more of these substances.

The pigment used as the white pigment is preferably titanium oxide. Titanium oxide may be surface-treated with an inorganic substance such as alumina or silica, may be surface-treated with an organic substance such as a higher fatty acid, or may be surface-treated with both of these substances. Further, surface treatment may be performed with a silane coupler, a titanium coupler, an aluminum coupler, a zirconium coupler, or the like.
In addition, rutile type titanium oxide is more preferable than anatase type titanium oxide. Since the rutile type is closer to pure white and the anatase type works as a photocatalyst, for example, when the dye is dissolved in a solvent (dispersion medium) and used in color, the dye is decomposed. Inactive rutile type titanium oxide is preferable.

There are roughly two types of pigments: light scattering and light absorption. Usually, white and metallic pigments are classified as a light scattering type, and other color (colored) pigments are classified as a light absorption type. In the present invention, the amount of the pigment to be used is different between the light-scattering pigment represented by white and the light-absorbing pigment of other colors.
In the dispersion for electrophoretic display of the present invention, the content of a white pigment (light scattering pigment) typified by titanium oxide is usually 5 to 50 weights with respect to 100 parts by weight of the solvent (dispersion medium) in the dispersion. Parts, preferably 10 to 30 parts by weight. In the case of colored pigments other than white (including black), the amount is usually 0.01 to 100 parts by weight, preferably 0.1 to 50 parts by weight, based on 100 parts by weight of the solvent (dispersion medium).

Among the colored pigments other than white, in particular, carbon black can achieve a black display with high color purity by using a relatively small amount. Therefore, the content of carbon black in the dispersion of the present invention is 100 (solvent (dispersion medium)). The amount is usually 0.01 to 20 parts by weight, preferably 0.1 to 50 parts by weight with respect to parts by weight.
The total amount of pigments contained in the dispersion of the present invention is usually about 30% by volume or less with respect to the dispersion.
The preferred average particle size of the pigment used in the dispersion of the present invention varies depending on the specific gravity, particle size, surface state, etc. of the pigment itself and cannot be determined uniformly. However, it is usually 0 from the viewpoint of dispersion stability and migration properties. The thickness is about 0.05 μm to 5 μm, preferably about 0.1 μm to 2 μm.

<Dispersant>
In order to improve the dispersibility of the pigment, the dispersion liquid for electrophoretic display of the present invention must contain at least a compound having a bonding chain represented by the general formula (A) in the molecule as a dispersant. It is.
The form of the dispersing agent in the dispersion liquid is not limited, but it exists in a form that is free or interacts with the pigment, and there is a dispersing agent that interacts with the pigment at least from the viewpoint of the dispersion stability of the pigment. A dispersion is preferred. Here, examples of the interaction include chemical adsorption and physical adsorption. In the dispersion liquid of the present invention, the form in which at least a part of the dispersant is adsorbed on the pigment can be confirmed, for example, by quantifying the dispersant adsorbed on the pigment. Specifically, for example, the pigment is filtered off from the dispersion, and the amount of the dispersant contained in the filtrate is determined and compared with the charged amount to confirm that the dispersant is adsorbed to the pigment and the amount. it can.

(Compound having a bond chain in which X is an oxygen atom in the general formula (A))
In general formula (A), examples of the compound having a bond chain in which X is an oxygen atom, that is, a urethane bond in the molecule include urethane polymers. Urethane polymers are suitable dispersants for dispersion stability. In general formula (A) typified by a urethane polymer, a compound having a bond chain in which X is an oxygen atom is (a) a hydroxyl group-containing compound having one or more hydroxyl groups (hereinafter referred to as a hydroxyl group-containing component). And (b) an isocyanate component as an essential component, and is produced in the presence of a reaction solvent by a known synthesis method using a chain extender, a chain length terminator, etc., which will be described later, if necessary. .
In general formula (A), (a) a hydroxyl group-containing component that is a constituent component of a compound having a bond chain in which X is an oxygen atom (hereinafter also referred to as a urethane bond-containing compound) is methanol, butanol, octanol, A compound containing one hydroxyl group, such as an aliphatic (including alicyclic, hereinafter the same) monoalcohol or phenolic compound having about 1 to 25 carbon atoms, preferably about 4 to 15 carbon atoms such as isopropanol and phenol. It may be a polyol component having two or more hydroxyl groups in the molecule. Preferably, it is a (a ′) polyol component described below.

(A ′) The polyol component is not particularly limited, and various polyol components having a number average molecular weight of about 500 to 10,000 which are usually used as a polyol in the production of a polyurethane resin can be used. Specifically, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, which are polymers such as ethylene oxide, propylene oxide, and tetrahydrofuran; polyoxyethylene-polyoxypropylene diol (block and / or random), polytetramethylene ether Examples include polyether polyols such as glycol.

  Furthermore, as other polyol components, ethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, hexanediol Aliphatic diols such as 1,8-octamethylenediol, bis (hydroxymethyl) cyclohexane, m- and p-xylylene glycol, 1,4-bis (2-hydroxyethoxy) benzene, 4,4′-bis ( Diols having a cyclic group such as 2-hydroxyethoxy) -diphenylpropane, aromatic dicarboxylic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, Aliphatic dicarbos such as malonic acid, azelaic acid and sebacic acid Polyester polyols obtained by dehydration condensation of acids, etc .; polyester polyols obtained by ring-opening polymerization of cyclic ester compounds; various known polymer polyols such as polycarbonate polyols, polybutadiene glycols, and the like of these compounds Examples are those in which one terminal hydroxyl group is alkoxylated with an alkyl group having 1 to 25 carbon atoms. These may be used alone or in combination of two or more.

Among these, from the viewpoint of obtaining a dispersion having a low refractive index, an aliphatic (including alicyclic group, hereinafter the same) polyol component is preferable. By using a dispersion liquid having a low refractive index, the reflectance in the electrophoretic display device is increased, and the brightness of white display is increased, so that the contrast is improved.
In addition, polyalkylene glycols or alkoxylated products thereof can be used as a polyol component to improve the dispersion stability of the pigment in the dispersion, thereby improving the contrast and reducing the driving voltage in the resulting electrophoretic display device. This is preferable because it is realized.

The polyalkylene glycol is more preferably a compound represented by the following structural formula, or an alkoxylated product of an alkyl group having 1 to 25 carbon atoms, preferably about 1 to 15 carbon atoms of the compound.
[Chemical formula 2]
^{HO- (R 2 O) n-} H
In the above formula, R ² represents an alkylene group having 1 to 4 carbon atoms. n represents an integer of 2 to 50, more preferably an integer of 2 to 10. When the number of carbons in R ² and the number of n exceed the upper limit, the solubility in a dispersion of a urethane bond-containing compound such as a urethane-based polymer that is obtained may decrease, and may not function sufficiently as a dispersant. If the lower limit is not reached, the advantage of having the partial structure may not be sufficiently exhibited.

  The (b) isocyanate component, which is another component of the urethane bond-containing compound, is not particularly limited, and known aromatic and aliphatic isocyanates can be used. An isocyanate group such as phenyl isocyanate may be one compound, or a polyisocyanate compound having two or more isocyanate groups in the molecule. Examples of the polyisocyanate compound include aromatics such as paraphenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, and tolidine diisocyanate. Diisocyanates; aliphatic diisocyanates such as hexamethylene diisocyanate, lysine methyl ester diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate; isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), ω, ω Alicyclic diisocyanates such as' -diisocyanate dimethylcyclohexane; lysine ester triisocyanate, 1,6,11- Tridecane such as ndecane triisocyanate, 1,8-diisocyanate-4-isocyanate methyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, tris (isocyanatephenylmethane), tris (isocyanatephenyl) thiophosphate Isocyanates; oligomers thereof, water addition products, and polyol addition products thereof.

  In addition, the urethane bond-containing compound in the present invention may be prepared by using the (a) component and the (b) component together with a (c) chain extender during the reaction. (C) As a chain extender, various well-known polyamine compounds can be used. Specific examples include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4-diamine and the like. Diamines having a hydroxyl group in the molecule, such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2 -Polyamine compounds such as hydroxypropylethylenediamine can also be used.

In addition, the urethane bond-containing compound is a compound containing an active hydrogen and a tertiary amino group in the same molecule or the same molecule in order to make the component (a) and component (b) easy to adsorb to the particles. It may be prepared by using a compound containing active hydrogen and a carboxylic acid in the reaction. Examples of the compound containing an active hydrogen and a tertiary amino group in the same molecule include those having an active hydrogen-containing group as the active hydrogen. Among them, an amino group, particularly a primary amino group is preferred. Examples of the tertiary amino group include a dialkylamino group and a nitrogen-containing heterocycle, and a dimethylamino group, a diethylamino group, an imidazole group, and the like are particularly preferable. As the compound having an active hydrogen and a tertiary amino group in the same molecule, a compound represented by the following general formula (B) is particularly preferable.
H ₂ N—R ³ —Z (B)
(In the formula, R ³ represents an alkylene group having 2 to 6 carbon atoms, and Z represents a nitrogen-containing heterocyclic group having 1 to 10 carbon atoms or a dialkylamino group having 1 to 6 carbon atoms.)

  In the amino compound represented by the general formula (B), examples of the dialkylaminoamine having 1 to 6 carbon atoms include N, N-dimethyl-1,3-propanediamine, N, N-diethyl-1,3. -Propanediamine, N, N-dipropyl-1,3-propanediamine, N, N-dibutyl-1,3-propanediamine, N, N-dimethylethylenediamine, N, N-dipropylethylenediamine, N, N-dibutyl Ethylenediamine, N, N-dimethyl-1,4-butanediamine, N, N-diethyl-1,4-butanediamine, N, N-dipropyl-1,4-butanediamine, N, N-dibutyl-1,4 -Butanediamine etc. are mentioned.

In the amino compound represented by the general formula (B), the nitrogen-containing heterocycle having 1 to 10 carbon atoms represented by Z includes a pyrazole ring, an imidazole ring, a triazole ring, a tetrazole ring, an indole ring, a carbazole ring, and an indazole ring. And nitrogen-containing hetero 6-membered rings such as benzimidazole ring, benzotriazole ring, benzoxazole ring, benzothiazole ring, benzothiadiazole ring and the like, and pyridine ring, pyridazine ring and isoquinoline ring. Of these, an imidazole ring or a triazole ring is preferable. Examples of the amino compound having a nitrogen-containing heterocyclic ring include 3-amino-1,2,4-triazole, 5- (2-amino-5-chlorophenyl) -3-phenyl-1H-1,2,4-triazole, 3-amino-5-phenyl-1H-1,3,4-triazole, 5-amino-1,4-diphenyl-1,2,3-triazole, 3-amino-1-benzyl-1H-2,4- And triazole.
Of the compounds represented by the general formula (B), particularly preferred are 1- (3-aminopropyl) imidazole and N, N-dimethylaminopropanediamine.

  Although there is no restriction | limiting in particular in the polystyrene conversion number average molecular weight of the urethane bond containing compound in this invention, Usually, about 100-50000, Preferably it is about 500-20000, More preferably, it is 1000-20000.

  In the dispersion for electrophoretic display of the present invention, the urethane bond-containing compound prepared in advance may be added to a solvent as a dispersant, but the above (a) hydroxyl group-containing component and (b) isocyanate component are added. The reaction product liquid containing the prepolymer obtained by reacting in a solvent containing an ester or ether solvent excellent in prepolymer solubility is preferably used as a dispersion. The ratio (weight ratio) between the prepolymer and the reaction solvent is about 60/40 to 20/80.

(Compound having a bonding chain in which X is an optionally substituted nitrogen atom represented by N (R ¹ ) in general formula (A))
In general formula (A), a bond chain in which X is an optionally substituted nitrogen atom represented by N (R ¹ ), that is, a compound having (substituted) urea bond in the molecule (hereinafter referred to as (substituted) urea bond) (Sometimes referred to as a chain-containing compound) includes (a) an amino group-containing compound having one or more amino groups (hereinafter also referred to as an amino group-containing component), and (b) an isocyanate component as an essential constituent component. And a chain extender, chain length terminator, etc., which will be described later, if necessary, and are produced in the presence of a reaction solvent by a known synthesis method.

  The (a) amino group-containing component which is a constituent component of the (substituted) urea-bonded chain-containing compound in the present invention may be a compound containing one amino group such as methylamine, dibutylamine, cyclohexylamine, dibenzylamine. Alternatively, it may be a polyamine component having two or more amino groups in the molecule. As the polyamine component, various known polyamines which are also used as chain extenders can be used. Specific examples include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4-diamine and the like. Diamines having a hydroxyl group in the molecule, such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2 -Polyamine compounds such as hydroxypropylethylenediamine can also be used.

  Among the above, aliphatic (including alicyclics; the same shall apply hereinafter) polyamine component is preferred from the viewpoint of obtaining a dispersion having a low refractive index when a (substituted) urea-bonded chain-containing compound is used as a dispersant. . By using a dispersion liquid having a low refractive index, the reflectance in the electrophoretic display device is increased, and the brightness of white display is increased, so that the contrast is improved.

The (b) isocyanate component, which is another component of the (substituted) urea bond chain-containing compound, is not particularly limited, and known aromatic and aliphatic isocyanates can be used. An isocyanate group such as phenyl isocyanate may be one compound, or a polyisocyanate component having two or more isocyanate groups in the molecule. Examples of the polyisocyanate include aromatic diisocyanates such as paraphenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, and tolidine diisocyanate. Aliphatic diisocyanates such as hexamethylene diisocyanate, lysine methyl ester diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate; isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), ω, ω ' -Alicyclic diisocyanates such as diisocyanate dimethylcyclohexane; lysine ester triisocyanate, 1,6,11-undeca Triisocyanates, 1,8-diisocyanate-4-isocyanate methyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, tris (isocyanatephenylmethane), tris (isocyanatephenyl) thiophosphate, etc. And oligomers thereof, water adducts, polyol adducts thereof, and the like.
Among them, an aliphatic polyisocyanate component is preferable from the viewpoint of obtaining a dispersion having a low refractive index, as in the case of the above-described (a) polyol component.

  As the (substituted) urea-bonded chain-containing compound of the present invention, it is particularly preferred that the raw material (a) amino group-containing component and (b) isocyanate component are both aliphatic, and (a) amino Most preferably, the group-containing component is a polyamine component and a part thereof is a polyalkylene glycol or an alkoxy product thereof.

  Although there is no restriction | limiting in particular in the polystyrene conversion number average molecular weight of the (substituted) urea bond chain containing compound of this invention, Usually, about 100-50000, Preferably it is about 500-20000, More preferably, it is 1000-20000.

  In the dispersion for electrophoretic display of the present invention, the (substituted) urea-bonded chain-containing compound prepared in advance may be added to a solvent as a dispersion medium, but the above (a) amino group-containing component and ( b) The isocyanate component can be reacted in the same type of solvent as the solvent in the display dispersion, and the resulting reaction product liquid containing the prepolymer can be used as it is in the dispersion. At that time, it is preferable to use a solvent containing an ester solvent or an ether solvent excellent in prepolymer solubility as a reaction solvent. The ratio (weight ratio) between the prepolymer and the reaction solvent is about 60/40 to 20/80.

  In the dispersion for electrophoretic display of the present invention, the content of the dispersant containing the compound having a bonding chain represented by the general formula (A) in the molecule depends on the type of the dispersant, but is usually pigment 100. The amount is 0.01 to 500 parts by weight, preferably 0.1 to 300 parts by weight, and most preferably 1 to 100 parts by weight, based on the solid content. If the amount of the dispersant is too large, not only the performance is saturated, but also the viscosity tends to increase and the electrophoretic properties tend to decrease.On the other hand, if the content is too small, the dispersion stability of the pigment particles by the dispersant is improved. May not be fully demonstrated.

<Electrically insulating solvent (dispersion medium)>
The electrically insulating solvent (dispersion medium) in the dispersion liquid for electrophoretic display of the present invention has a low dielectric constant, a high volume resistance, a low refractive index, a low viscosity, water without adversely affecting toxicity and the environment. Are preferably slightly soluble (10 ppm or less) and have a high boiling point (100 degrees or more).
Examples of such solvents include epoxide solvents such as decane epoxide and dodecane epoxide; cyclohexyl vinyl ether, and vinyl ether solvents such as Decave.RTM. (Trade name: International Flavors & Fragrances, Inc.); mesitylene, xylene Aromatic hydrocarbon solvents such as alkylbenzene such as toluene and naphthalene; halogenated organic solvents such as tetrafluorodibromoethylene, tetrachloroethylene, trifluorochloroethylene, 1,2,4-trichlorobenzene, carbon tetrachloride; Hydrocarbon solvents such as tetradecane; Isopar.RTM. Series (trade name: Exxon (Company)), Norpar.RTM. (Product name: Liquid normal paraffin), Shell-Sol.RTM. (Product name: Shell (Company) )), Sol-Trol.RTM. (Trade name: Shell (company)), aliphatic carbonization such as naphtha and other petroleum solvents. Examples thereof include a hydrogen solvent, an ester solvent, and an ether solvent.

  Further, in the dispersion for electrophoretic display of the present invention, a dispersant is used for improving the dispersibility of the pigment, but the compound having a bonding chain represented by the general formula (A) in the molecule generally has solubility. The type of solvent used as a dispersion medium is often limited. In the present invention, by using a relatively polar ester solvent and ether solvent as the solvent, the compound having a bond chain represented by the general formula (A) in the molecule is dissolved, and the dispersibility of the pigment is improved. Electrophoretic properties can also be improved.

The solvent as a dispersion medium in the display dispersion of the present invention preferably contains at least one of an ester solvent and an ether solvent, and even a solvent composed only of an ester solvent and an ether solvent is a feature of the present invention. Unless it impairs general performance, it may be a mixture with other solvents.
In the present invention, as described above, an ester solvent, an ether solvent, or a compound having a bonding chain represented by the general formula (A) in a molecule of a dispersion liquid (dispersion medium) containing these solvents in the molecule. A prepolymer can be produced to form a dispersant solution, and the produced liquid (dispersant solution) can be used as it is, or the produced liquid can be blended with a solvent for the dispersion to prepare a display dispersion.

(Ester solvent)
As the ester solvent, for example, an esterified product of an alkylene glycol alkyl ether, an aliphatic carboxylic acid ester, an aliphatic alkoxycarboxylic acid ester or the like is preferably used.
The alkylene glycol alkyl ether constituting the esterified product of alkylene glycol alkyl ether is mono-, di- or tri-alkylene glycol mono of alkylene glycol having 2 to 10 carbon atoms, preferably 2 to 3 carbon atoms such as ethylene glycol and propylene glycol. Or a dialkyl ether is mentioned, An alkyl group is a C1-C10, Preferably it is a C1-C4 linear or branched alkyl group.

  Specific examples of the alkylene glycol alkyl ether include, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, ethylene glycol dipropyl ether, ethylene Ethylene glycol ethers such as glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol dibutyl ether, ethylene glycol isoamyl ether, ethylene glycol monohexyl ether, ethylene glycol mono 2-ethylhexyl ether, methoxyethoxyethanol, ethylene glycol monoallyl ether Diethylene glycol such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol monohexyl ether, diethylene glycol mono 2-ethylhexyl ether Ethers: Triethylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoisopropyl ether, triethylene glycol monobutyl ether, triethylene glycol dimethyl ether Triethylene glycol ethers such as Le like.

Other examples include propylene glycol ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, butoxypropanol; dipropylene glycol monomethyl ether, dipropylene glycol monoethyl Examples include dipropylene glycol ethers such as ether, dipropylene glycol monopropyl ether, and dipropylene glycol monobutyl ether; and tripropylene glycol ethers such as tripropylene glycol monomethyl ether.
Of these, propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether and butoxypropanol are preferred.

  Examples of the esterified products of alkylene glycol ethers include esterified products of the above-mentioned alkylene glycol ethers with aliphatic carboxylic acids, and as aliphatic carboxylic acids, the alkyl chain of the carboxylic acid has a linear or branched carbon number of 1 to 1. Examples thereof include carboxylic acids having 10 to 4 carbon atoms, preferably those having been acetated with acetic acid. Typical examples include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate and other ethylene glycol monoalkyl ether alkylates, propylene glycol monomethyl. Propylene glycol monoalkyl ethers such as ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, propylene glycol monomethyl ether propionate, propylene glycol monomethyl ether butyrate Ruarukireto and the like. Of these, propylene glycol monoalkyl ether acetate is preferred, and propylene glycol monomethyl ether acetate is particularly preferred. These can be used alone or as a mixture of two or more.

Preferably aliphatic carboxylic acid esters used are esters of the formula R ⁴ COOR ^5, wherein R ⁴ is 1 to 6 carbon atoms, preferably an alkyl group of 1 to 2, R ⁵ Represents an alkyl group having 1 to 10 carbon atoms, preferably 4 to 10 carbon atoms. Here, the alkyl group represented by R ⁴ and R ⁵ may be either linear or branched. Specifically, acetate esters such as ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, amyl acetate; methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate, amyl propionate, propion Examples include propionic acid esters such as acid hexyl. Among these, since they have a relatively high boiling point, acetate esters such as ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, and amyl acetate are more preferable. These can be used alone or as a mixture of two or more.

The aliphatic alkoxycarboxylic acid ester is one in which at least one hydrogen atom bonded to the carbon atom of the alkyl group represented by R ⁴ in the carboxylic acid ester represented by the formula R ⁴ COOR ⁵ is substituted with an alkoxy group. And the alkyl group constituting the alkoxy group has 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. Specifically, alkoxycarboxylic acid esters substituted with an alkoxy group such as methoxy group, ethoxy group, propoxy group, butoxy group, isobutoxy group, pentyl group, hexyl group, and the like of acetates and propionates similar to the above. Kind. Among these, alkoxypropionates such as methyl methoxypropionate, ethyl ethoxypropionate, methyl propoxypropionate, methyl butoxypropionate, ethyl isobutoxypropionate, pentyloxypropionate, hexyloxypropionate hexyl Preferred examples include ethyl ethoxypropionate, particularly preferred. These can be used alone or in admixture of two or more.

(Ether solvent)
Examples of ether solvents include diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, dihexyl ether, ethyl vinyl ether, butyl vinyl ether, anisole, phenetole, butyl phenyl ether, pentyl phenyl ether, methoxy toluene, benzyl ethyl ether, diphenyl ether. Aliphatic or aromatic ethers such as propylene oxide, 1,2-epoxybutane, dioxane, trioxane, furan, 2-methylfuran, tetrahydrofuran, tetrahydropyran, cineol, etc .; 1 , 2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane, diethylene glycol dimethyl ether, die Glycol diethyl ether, diethylene glycol dibutyl ether, glycol ethers such as glycerin ether; crown ethers, methylal, acetal, and the like. These can be used alone or as a mixture of two or more.

As described above, the solvent as the dispersion medium in the present invention contains the above ester solvent and ether solvent, and as a mixture with other solvents as long as the characteristics of the display dispersion of the present invention are not impaired. May be used.
Examples of the solvent that can be used in combination include, but are not limited to, organic solvents as exemplified below.
Examples of solvents include epoxides such as decane epoxide and dodecane epoxide; cyclohexyl vinyl ether, and Decave.RTM. (Trade name: International Flavors
& Fragrances, Inc. Vinyl ethers such as toluene; aromatic hydrocarbons such as toluene and naphthalene; halogenated organic solvents such as tetrafluorodibromoethylene, tetrachloroethylene, trifluorochloroethylene, 1,2,4-trichlorobenzene, carbon tetrachloride; Hydrocarbons such as dodecane and tetradecane; Isopar.RTM. Series (trade name: Exxon (trade name)), Norpar.RTM. (Trade name: liquid normal paraffin), Shell-Sol.RTM. (Trade name: Shell ( Sol-Trol.RTM. (Trade name: Shell (company)), naphtha, and other aliphatic hydrocarbons such as petroleum solvents.

  Further, as other solvents, silicone oils such as octamethylcyclosiloxane, polymer cyclic siloxane, poly (methylphenylsiloxane), hexamethyldisiloxane, polydimethylsiloxane, etc .; poly (chlorotrifluoroethylene) polymer (Halogenated hydrocarbon Inc) .), Galden.RTM. (Trade name: perfluorinated ether; Ausimont (trade name)), Krytox.RTM. (Trade name: Du pont (trade name)), and the like can also be used.

  When the ester solvent and the ether solvent are mixed with other solvents as typified above, the ratio of the ester solvent and the ether solvent in the total amount of the solvent varies depending on the type, but usually 5 ~ 50% by weight.

In order to improve the contrast of the display device, color may be added by dissolving or mixing the dye in the dispersion medium. Dyes to be used can be appropriately selected and used from known dyes, and may be fluorescent or photofunctional. Examples thereof include, but are not limited to, the following dyes.
Specific examples of suitable dyes include oil red dyes: azo dyes such as Sudan Red and Sudan black dyes; oil blue dyes: anthraquinone dyes such as Macrolex Blue dyes; Michael Hydrol, Malachite Green, Crystal Violet, And triphenylmethane dyes such as auramine O.

<Optional component>
In the dispersion liquid for electrophoretic display of the present invention, the pigment particles have a clear and stable surface by combining the compound having a bond chain represented by the general formula (A) in the molecule with an ester solvent or an ether solvent. Since it has an electric charge, a charge control agent is usually not necessary, but if necessary, a general charge control agent may be used in combination.
As the charge control agent, substances known for liquid toner, electrophoretic display, non-aqueous paint, engine oil additive and the like can be used. Examples thereof include organic sulfates, organic sulfonates, metal soaps, block or comb copolymers, organic amides, organic zwitterions, organic phosphates, and organic phosphonates.

Useful organic sulfates and organic sulfonates include sodium bis (2-ethylhexyl) sulfosuccinate, calcium dodecylbenzenesulfonate, calcium petroleum sulfonate, neutral or basic dinonylnaphthalene sulfonate barium, neutral or basic dinonylnaphthalene Examples include, but are not limited to, calcium sulfonate, sodium dodecylbenzenesulfonate and ammonium lauryl sulfate.
Suitable metal soaps include, but are not limited to, for example, neutral or basic barium petroleum petroleum acid, calcium petroleum acid, naphthenic acid Co, Ca, Cu, Mn, Ni, Zn, and Fe salts. , Ba, Al, Zn, Cu, Pb, and Fe salts of stearic acid, aluminum tristearate, aluminum octoate, lithium heptanoate, iron stearate, iron distearate, barium stearate, chromium stearate, magnesium octoate Divalent or trivalent metal salts of carboxylic acids such as calcium stearate, iron naphthenate, zinc naphthenate, Mn- or Zn-heptanoate, and Ba-, Al-, Co-, Mn- or Zn-octoate. Can be mentioned.

  Useful block and comb type copolymers include, but are not limited to, the polymer (A) of quaternized product of 2- (N, N) dimethylaminoethyl methacrylate with methyl-p-toluenesulfonate and poly- AB diblock copolymer with 2-ethylhexyl methacrylate (B), having an oil-soluble tail of poly (12-hydroxystearic acid) and having a molecular weight of about 1800, an oil of poly (methyl methacrylate-methacrylic acid) Examples include comb-type copolymers having a group anchored to a soluble anchor group.

  Organic amides include, but are not limited to, polyisobutylene succinic amides such as OLOA 1200, and N-vinyl pyrrolidone polymers. Useful organic zwitterions include, but are not limited to lecithin. Useful organic phosphates and phosphonates include, but are not limited to, sodium monophosphate and diglyceride sodium salts with saturated or unsaturated acid substituents.

In order to enhance the effect of the charge control agent, the following compounds can be added. However, the concentration of addition to the solvent as the dispersion medium is desirably 2% by weight or less, and 5 to 20 g is desirably added to 100 parts by weight of the pigment particles. Specific examples of the additive compound include, for example, ethylene glycol, 2,4,7,9-tetramethyl-decane-4,7-diol, poly (propylene glycol), pentaethylene glycol, tripropylene glycol, triethylene glycol, Examples include glycerol, pentaerythritol, glycerol-tri-12 hydroxystearate, propylene glycerol monohydroxystearate, and ethylene glycol monohydroxystearate.
Furthermore, amino alcohol compounds having at least one alcohol functional group and one amine functional group in the same molecule may be mentioned, for example, triisopropanolamine, triethanolamine, ethanolamine, 3-amino-1-propanol, Examples include, but are not limited to, o-aminophenol, 5-amino-1-pentanol, and tetra (2-hydroxyethyl) ethylene-diamine.

In the dispersion for electrophoretic display of the present invention, a compound having a bond chain represented by the general formula (A) in the molecule is used, but in order to suppress aggregation of pigment particles, adhesion to electrodes, etc., the present invention Other known dispersants or surfactants may be contained as long as the characteristic performance of the dispersion is not impaired.
As the dispersant that can be contained, for example, a non-aqueous surfactant that is a typical high-resistivity liquid used in suspensions for electrophoretic displays is used. Examples of the surfactant include, but are not limited to, glycol ethers, acetylene glycols, alkanolamines, sorbitol derivatives, alkylamines, quaternary ammonium salts, imidazolines, dialkyl oxides, and sulfosuccinates.
Furthermore, as a surfactant that can be used in combination with a compound having a bonding chain represented by the general formula (A) in the molecule, various interfaces of cationic, anionic, nonionic, or amphoteric polymers or low molecules are used. Specific examples of the surfactant include surfactants described in JP-A No. 2001-125147.

<Method for preparing dispersion for display>
The dispersion for electrophoretic display of the present invention is produced according to a known ordinary method. For example, it can be obtained by preparing a pigment dispersion by dispersing a dispersant, a pigment, an organic solvent and other optional components, and if necessary, further mixing and mixing a resin, an additive and the like to obtain a uniform solution. . Usually, the pigment is preferably preliminarily dispersed using a paint conditioner, sand grinder, ball mill, roll mill, stone mill, jet mill, homogenizer, ultrasonic disperser or the like. Since the pigment is finely divided by the dispersion treatment, the electrophoretic characteristics and the color characteristics of the pigment dispersion are improved.
When the dispersion medium is dispersed by using a sand grinder or the like, it is preferable to use 0.1 mm to several mm diameter glass, ceramic such as alumina or zirconia, or metal beads as the medium. The dispersion condition is usually a temperature of 0 to 100 ° C., preferably in a range of room temperature to 80 ° C. The dispersion time is appropriately adjusted because the appropriate time varies depending on the composition of the dispersion (coloring material, solvent, dispersant) and the size of the sand grinder.
As the dispersant, as described above, the product liquid (dispersant solution) obtained during the synthesis of the dispersant can be used as it is.

<Microencapsulation>
The dispersion liquid for electrophoretic display of the present invention can be encapsulated in microcapsules and used as particles for electrophoretic display.
Various methods such as a known in-situ method, an interfacial polymerization method, and a coacervation method can be appropriately employed as the microencapsulation method, but are not limited thereto. The wall material used for microencapsulation is not particularly limited, but is preferably a material that transmits light sufficiently. Specific examples include gelatin, polyamide, polyester, polyurea, urea-formaldehyde resin and the like.
The microcapsule particles are usually about 0.5 to 500 μm, preferably about 1.0 to 100 μm.

<Method of forming electrophoresis cell>
The electrophoretic display device using the dispersion liquid for electrophoretic display of the present invention requires the above-described measures for preventing sedimentation of the pigment particles. Specifically, the microencapsulation of the electrophoretic display dispersion liquid and the electrophoresis Means such as partition formation in the cell are applied. Production of an electrophoretic display device using microencapsulation of a dispersion can be performed by, for example, the method described in US Pat. No. 6,300,932. For example, known literature [Microencapsulation, Processes and Applications, (IE Vandegaer, ed.), Plenum Press, New York, NY (1974), and Gutcho, Microcapsules and Mircroencapsulation Techniques, Nuyes Data Corp., Park Ridge, NJ (1976) Or a microcapsule of the above-mentioned dispersion using a known encapsulation method described in US Pat. No. 4,087,376, etc., and printing the microcapsule on the electrode substrate of the electrophoretic display device, the other electrode To make a display. A binder resin may be used during microcapsule printing.

  An electrophoretic display device in which partition walls are formed in an electrophoresis cell can be manufactured by a method described in, for example, WO01 / 67170A1. For example, after a photocurable resin monomer is printed on the electrode substrate in a grid pattern by microembossing technology, this is cured by irradiation with ultraviolet rays to form partition walls. Thereafter, the dispersion liquid is poured into the partition walls, which are sealed to obtain a display.

Examples of the electrophoretic display device using the electrophoretic display dispersion liquid and the electrophoretic display particles of the present invention include the following forms, but the electrophoretic display device of the present invention is not limited to these. It is not something.
(1) A pair of base materials for display provided with electrodes on one side of a substrate are formed so that the electrode surfaces face each other through a spacer to form a space, and the space is filled with the dispersion liquid for electrophoretic display of the present invention. An electrophoretic display device in which at least one of the pair of display substrates is provided with a transparent electrode on one side of a transparent substrate (FIG. 1).
(2) A space is formed by allowing an insulating film to face a display substrate provided with an electrode on one side of the substrate through a spacer, and the space is filled with the dispersion liquid for electrophoretic display of the present invention. An electrophoretic display device in which at least one of a base material and an insulating film is transparent (FIG. 2).

(3) A pair of base materials for display provided with electrodes on one side of the substrate is formed by arranging the electrode surfaces facing each other to form a space, and the space is filled with the electrophoretic display particles (microcapsules) of the present invention, An electrophoretic display device (FIG. 3) in which at least one of the pair of display substrates is provided with a transparent electrode on one side of a transparent substrate.
(4) A space is formed by making an insulating film face a display substrate provided with electrodes on one side of the substrate, the space is filled with the electrophoretic display particles (microcapsules) of the present invention, and the display substrate An electrophoretic display device in which at least one of the material and the insulating film is transparent (FIG. 4).
(5) An electrophoretic display in which a coating layer containing the electrophoretic display particles (microcapsules) of the present invention and a binder is formed on a display substrate having a transparent or opaque electrode on one side of a transparent or opaque substrate. Device (Figure 5).

1 to 5, 1 and 1 ′ are substrates, 2 and 2 ′ are transparent electrodes, 3 is a display dispersion, 4 is a spacer, 5 is an insulating film, and 6 is filled with display particles (microcapsules). 7 is a dispersion-encapsulated microcapsule, and 8 is a microcapsule and binder-containing coating layer.
In addition, in the electrophoretic display device having the configuration shown in FIGS. 1 to 5, the spacer is not necessarily used, and can be arbitrarily selected and used according to the form of the device, and a device not shown is also required. May be used. The electrophoretic display device of the present invention is not limited to the above-described configuration as long as its function is not impaired.

  In addition, as the electrophoretic display device of the present invention, in the electrophoretic display device having the configuration of (5), the electrophoretic display device is provided with an overcoat layer on the coating layer containing the particles for electrophoretic display and the binder. An electrophoretic display device in which a printing layer is provided on at least a part of the overcoat layer and / or at least a part of the display substrate, and a print protective layer is provided on the printing layer. Examples thereof include electrophoretic display devices.

  The electrophoretic display device having any one of the above configurations of the present invention is an electrophoretic display device provided with an information recording unit in addition to a display unit capable of forming and erasing an image by applying and controlling an electric field. May be. In that case, an electrophoretic display device in which the information recording unit is a recording unit capable of writing and reading information records by the action of magnetism, an electrophoretic display device in which the information recording unit is an integrated circuit memory or an optical memory, and information recording The electrophoretic display device is a recording unit capable of reading out information records by the action of light, and the information recording unit displays information indicating the front and back of the display medium and / or information indicating the position of the display medium. An electrophoretic display device can be obtained.

EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not restrict | limited to a following example, unless the summary is exceeded.
In the following examples, the isocyanate content of the prepolymer was measured by the following method.
<Isocyanate content measurement method>
The prepolymer was collected in a conical beaker containing 20 ml of a 0.05N di-n-butylamine toluene solution, and back titrated with a 0.5N hydrochloric acid aqueous solution.

<Example 1>
To a three-necked flask, 8.75 g of xylene (manufactured by Kanto Chemical Co., Inc.) and 8.75 g of methoxypropyl acetate (manufactured by Tokyo Chemical Industry Co., Ltd.) are added, and 0.86 g of octanol (manufactured by Tokyo Chemical Industry Co., Ltd.) is further added. Polyisocyanate (Mitsubishi Chemical Corporation; trade name: Mytec NY-220A: adduct oligomer of polyester triol and isophorone diisocyanate: solid content 70% by weight, isocyanate group content 8.2% by weight) 6 After adding .64 g, a cooling tube, a nitrogen introducing tube and a stirrer were attached, and the mixture was heated at 90 ° C. for 2 hours while flowing nitrogen. Then, after cooling the flask contents to room temperature, a dispersant solution A1 having a solid content of 30% by weight was obtained.

Next, 2 g of the obtained dispersant solution A1 was added to 5.9 g of mesitylene (manufactured by Kanto Chemical Co., Inc.), 2 g of titanium oxide and 20 g of zirconia beads were added, and the mixture was dispersed for 3 hours with a paint shaker. 5 mg of Sudan Black B) was added and dissolved to obtain a titanium oxide dispersion B1 for electrophoretic display. Titanium oxide dispersion B1 was filled between a pair of ITO transparent electrodes set at an electrode interval of 80 μm, and a DC voltage was applied between the electrodes in the order of + 5V, −5V, + 10V, −10V, + 5V and −5V for 10 seconds, The brightness L ^* value in CIE 1976 on the electrode 10 seconds after voltage application was measured with a chromaticity meter (manufactured by Toppan Printing, CM-1000, measurement condition; D65 light source 2 degree visual field). The results are shown in Table 1.

<Example 2>
To a three-necked flask, 8.7 g of xylene (manufactured by Kanto Chemical Co., Inc.) and 8.7 g of methoxypropyl acetate (manufactured by Tokyo Chemical Industry Co., Ltd.) were added, 0.8 g of octanol, polyethylene glycol monomethyl ether (Aldrich Co., Ltd.) Product: Number average molecular weight 350) 0.24 g was added and mixed and dissolved well. After adding 6.64 g of polyisocyanate (Mitsubishi Chemical Co., Ltd .; trade name: MYTEC NY-220A), a cooling tube and nitrogen were introduced. A tube and a stirrer were attached, and the mixture was heated at 90 ° C. for 2 hours while flowing nitrogen. Then, after cooling the flask contents to room temperature, Dispersant Solution A2 was obtained. Next, using the obtained dispersant solution A2, a titanium oxide dispersion B2 for electrophoretic display was prepared in the same manner as in Example 1, and the color characteristics of the dispersion B2 when a DC voltage was applied were measured. It is shown in Table 1.

<Example 3>
10 g of xylene (manufactured by Kanto Chemical Co., Inc.) and 10 g of methoxypropyl acetate (manufactured by Tokyo Chemical Industry Co., Ltd.) are added to a three-necked flask, and further 4 g of polyethylene glycol stearate (manufactured by Tokyo Chemical Industry Co., Ltd .: number average molecular weight 554). After adding 5 g of polyisocyanate (Mitsubishi Chemical Co., Ltd .; trade name: Mytec NY-220A), attach a cooling tube, a nitrogen introducing tube and a stirrer, and flow nitrogen at 90 ° C. For 2 hours. Then, after cooling the flask contents to room temperature, Dispersant Solution A3 was obtained. Then, using the obtained dispersant solution A3, a titanium oxide dispersion B3 for electrophoretic display was prepared in the same manner as in Example 1, and the color characteristics of the dispersion B3 when a DC voltage was applied were measured. It was shown in 1.

<Comparative Example 1>
Add 2.6 g of titanium oxide and 20 g of zirconia beads to 7.6 g of mesitylene (manufactured by Kanto Chemical Co., Ltd.), disperse with a paint shaker for 3 hours, and then add 8 mg of dye (Sudan Black B) to dissolve and electrophoretic display Titanium oxide dispersion B4 was obtained. Since this dispersion B4 had a high viscosity, it could not be filled in the electrophoretic measurement cell, and the electrophoretic characteristics could not be measured.

<Comparative example 2>
Add 0.23 g of SPAN83 (manufactured by Tokyo Chemical Industry Co., Ltd .; sorbitan surfactant) and 2.3 g of titanium oxide to 7.5 g of xylene, add 20 g of zirconia beads, and disperse with a paint shaker for 3 hours. 8 mg of a dye (Sudan Black B) was added and dissolved to obtain a titanium oxide dispersion B5 for electrophoretic display. The color characteristics of this dispersion B5 when a DC voltage was applied were measured, and the results are shown in Table 1.

In Table 1, the larger the L * value, the more white the display is, and the larger the difference (ΔL * value) between the L * values when applying the same positive / negative voltage, the higher the contrast. .
As is apparent from Table 1, Examples 1 to 3 were driven even with a low voltage of ± 5 V, and even when ± 10 V was applied, the characteristics did not change greatly and were stable dispersions. The white display and contrast were good.
On the other hand, in Comparative Example 2, a sufficient white display is not obtained as is apparent from the small L * value when ± 5 V is applied after -10 V is applied, and the contrast is low because the ΔL * value is small. I understand that. This is because titanium oxide adhered to the electrode surface when a voltage of -10 V was applied, and thereafter no clear electrophoretic properties were exhibited.

<Example 4>
Fully dehydrated propylene glycol monomethyl ether acetate (hereinafter abbreviated as PGMEA; manufactured by Wako Pure Chemical Industries, Ltd.) 36.7 g, polyisocyanate (Mitsubishi Chemical Corporation: trade name: Mytec GP750A) : Tolylene diisocyanate trimer: 6.6 g of solid content 50 wt%, isocyanate group content 7.8 wt%), and after adding 0.02 g of dibutyltin dioctate (Tokyo Kasei Co., Ltd.) as a catalyst, A cooling tube and a nitrogen introduction tube were attached and heated at 70 ° C. for 10 minutes while flowing nitrogen. Next, 5.0 g of polypropylene glycol having a number average molecular weight of 2400 (manufactured by Sanyo Kasei Co., Ltd .; trade name: Newpol LB-1715) with one end being a butoxy group is added with stirring and reacted at 70 ° C. for 1 hour. An adduct was formed. The isocyanate group content of the adduct was measured and confirmed.

  Next, 1.0 g of polypropylene glycol (manufactured by Sanyo Chemical Co., Ltd .; trade name Sannix PP-1000) was added to the above product and reacted at 70 ° C. for 1 hour to obtain an adduct. The isocyanate content was also confirmed for this adduct. Furthermore, 0.2 g of N, N-dimethyl-1,3-propanediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to this adduct and reacted at 40 ° C. for 1 hour. Finally, 0.2 g of n-propanol (manufactured by Kanto Chemical Co., Inc.) was added and all remaining NCO groups were reacted to obtain a dispersant solution A4 having a solid concentration of 20% by weight.

  Next, 3 g of the obtained dispersant solution A4 was added to 4.9 g of diethylbenzene (manufactured by Tokyo Chemical Industry Co., Ltd.), 2 g of titanium oxide and 20 g of zirconia beads were added, and the mixture was dispersed for 3 hours with a paint shaker. (Oil blue N) 5 mg was added and dissolved to obtain a titanium oxide dispersion B4 for electrophoretic display. Titanium oxide dispersion solution B4 was filled between a pair of ITO transparent electrodes set at an electrode interval of 80 μm, and a DC voltage was applied between the electrodes in the order of +5 V, −5 V, +10 V, −10 V, +5 V and −5 V for 10 seconds, The lightness L * value in CIE 1976 on the electrode 10 seconds after voltage application was measured with a chromaticity meter (CM-1000 manufactured by Toppan Printing Co., Ltd., measurement condition D65 light source 2 degree visual field). The results are shown in Table 1.

<Example 5>
In Example 4, 3.3 g of polyisocyanate, 2.5 g of polypropylene glycol having a number-average molecular weight of 2400 with one end being a butoxy group, 0.1 g of N, N-dimethyl-1,3-propanediamine, A dispersant solution A5 was obtained in the same manner as in Example 4 except that the amount was changed to 0.6 g of n-propanol, polypropylene glycol was not used, and the amount of PGMEA was adjusted so that the solid content concentration was 10% by weight.

  Next, 6 g of the obtained dispersant solution A5 was added to 1.9 g of diethylbenzene (manufactured by Tokyo Chemical Industry Co., Ltd.), 2 g of titanium oxide and 20 g of zirconia beads were added, and the mixture was dispersed for 3 hours with a paint shaker. 5 mg of (Oil Blue N) was added and dissolved to obtain a titanium oxide dispersion B5 for electrophoretic display. The titanium oxide dispersion solution B5 was filled between a pair of ITO transparent electrodes set at an electrode interval of 80 μm, and a DC voltage was applied between the electrodes in the order of + 5V, −5V, + 10V, −10V, + 5V and −5V for 10 seconds, The lightness L * value in CIE 1976 on the electrode 10 seconds after voltage application was measured with a chromaticity meter (CM-1000 manufactured by Toppan Printing Co., Ltd., measurement condition D65 light source 2 degree visual field). The results are shown in Table 1.

<Example 6>
In Example 4, the amount of polyisocyanate is 3.1 g, the number average molecular weight of 2400 having a number-average molecular weight of 2400 is 2.4 g of polypropylene glycol, and the number average molecular weight of polypropylene glycol is having a methoxy group at one end. Polyethylene glycol (manufactured by Sanyo Chemical Co., Ltd., trade name: UNIOX M-2000) was changed to 3.2 g, and further the amount of N, N-dimethyl-1,3-propanediamine was 0.1 g and the amount of n-propanol Was 0.6 g, and a dispersant solution A6 was obtained in the same manner as in Example 4 except that the amount of PGMEA was adjusted so that the solid content concentration was 20% by weight.
Next, using the obtained dispersant solution A6, a titanium oxide dispersion B6 for electrophoretic display was prepared in the same manner as in Example 4, and the color characteristics of the dispersion B6 when a DC voltage was applied were measured. The results are shown in Table 1.

<Example 7>
In Example 4, polypropylene glycol having a number average molecular weight of 2400 having a polyisocyanate amount of 5.0 g and one end being a butoxy group, and a polyethylene glycol having a number average molecular weight of 2000 having a methoxy group at one end (Sanyo Kasei) Co., Ltd., trade name: UNIOX M-2000) 3.2 g, polypropylene glycol amount 0.8 g, N, N-dimethyl-1,3-propanediamine amount 0.2 g, n-propanol amount 0. Dispersant solution A7 was obtained in the same manner as in Example 4 except that the amount of PGMEA was adjusted to 9 g and the solid content concentration was 20% by weight.
Then, using the obtained dispersant solution A7, a titanium oxide dispersion B7 for electrophoretic display was prepared in the same manner as in Example 4, and the color characteristics of the dispersion B7 when a DC voltage was applied were measured. The results are shown in Table 1.

<Example 8>
In Example 4, a polyisocyanate is an adduct of tolylene diisocyanate trimethylolpropane (manufactured by Nippon Polyurethane Industry Co., Ltd .: trade name Coronate L, solid content 75% by weight, isocyanate group content 13.3% by weight) The amount of polypropylene glycol having a number average molecular weight of 2400 and having a butoxy group at one end is 9.6 g, the amount of N, N-dimethyl-1,3-propanediamine is 0.4 g, and the amount of n-propanol Was 0.6 g, polypropylene glycol was not used, and a dispersant solution A8 was obtained in the same manner as in Example 4 except that the amount of PGMEA was adjusted so that the solid content concentration was 20% by weight.
Next, using the obtained dispersant solution A8, a titanium oxide dispersion B8 for electrophoretic display was prepared in the same manner as in Example 4, and the color characteristics of the dispersion B8 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 9>
39.3 g of PGMEA sufficiently dehydrated in a three-necked flask, polyisocyanate (manufactured by Mitsubishi Chemical Co., Ltd .: trade name Mytec NY730A: trimer of hexamethylene diisocyanate: solid content 75% by weight, isocyanate group content 15.3 2.6% by weight) and 0.02 g of dibutyltin dioctoate (manufactured by Tokyo Chemical Industry Co., Ltd.) as a catalyst were added, and then a cooling tube and a nitrogen introducing tube were attached and heated at 70 ° C. for 10 minutes while flowing nitrogen. Then, under stirring, 6.3 g of polypropylene glycol having a number average molecular weight of 2400 having a butoxy group at one end (manufactured by Sanyo Kasei Co., Ltd .; trade name: Newpol LB-1715) was added and reacted at 70 ° C. for 1 hour. An adduct was formed. The adduct was confirmed by measuring its isocyanate group content.
Next, 0.1 g of n-propanol (manufactured by Kanto Chemical Co., Inc.) was added to the product, and 1.3 g of polypropylene glycol (manufactured by Sanyo Chemical Co., Ltd .; trade name Sannix PP-1000) was added at 70 ° C., 1 The reaction was carried out for a time to obtain an adduct. The adduct was confirmed by measuring the isocyanate group content. Finally, 0.9 g of N, N-dimethyl-1,3-aminopropylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) is added to the resulting adduct to react with all remaining NCO groups, and the solid content concentration is 20 wt. % Dispersant solution A9 was obtained.

  Next, 3 g of the obtained dispersant solution A9 was added to 4.9 g of diethylbenzene (manufactured by Tokyo Chemical Industry Co., Ltd.), then 2 g of titanium oxide and 20 g of zirconia beads were added and dispersed for 3 hours with a paint shaker. 5 mg of oil blue N) was added and dissolved to obtain a titanium oxide dispersion B4 for electrophoretic display. Titanium oxide dispersion B9 was filled between a pair of ITO transparent electrodes set at an electrode interval of 80 μm, and a DC voltage was applied between the electrodes in the order of +5 V, −5 V, +10 V, −10 V, +5 V and −5 V in 10 seconds, The lightness L * value in CIE 1976 on the electrode 10 seconds after voltage application was measured with a chromaticity meter (CM-1000 manufactured by Toppan Printing Co., Ltd., measurement condition D65 light source 2 degree visual field). The results are shown in Table 1.

<Example 10>
In Example 9, the polyisocyanate was changed to 1.8 g of an isophorone diisocyanate trimer (Degussa, trade name: T-1890, solid content: 100 wt%, isocyanate group content: 15.4 wt%), and 6.6 g of polypropylene glycol having a number average molecular weight of 2400 having one end at a butoxy group, 1.4 g of polypropylene glycol, 0.9 g of N, N-dimethyl-1,3-aminopropylamine, Dispersant solution A10 was obtained in the same manner as in Example 9 except that n-propanol was not used and the amount of PGMEA was adjusted so that the solid content concentration was 20% by weight.
Next, using the obtained dispersant solution A10, a titanium oxide dispersion B10 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B10 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 11>
In Example 9, a polyisocyanate is an adduct of tolylene diisocyanate trimethylolpropane (manufactured by Nippon Polyurethane Industry Co., Ltd .: trade name Coronate L, solid content 75% by weight, isocyanate group content 13.3% by weight) The amount was changed to 4 g, and the amount of polypropylene glycol having a number average molecular weight of 2400 with one end being a butoxy group was 6.5 g, the amount of n-propanol was 0.04 g, the amount of polypropylene glycol was 1.4 g, and N, N-dimethyl Dispersant solution A11 was obtained in the same manner as in Example 9 except that the amount of -1,3-aminopropylamine was 0.9 g and the amount of PGMEA was adjusted so that the solid content concentration was 20% by weight.
Next, using the obtained dispersant solution A11, a titanium oxide dispersion B11 for electrophoretic display was prepared in the same manner as in Example 4, and the color characteristics of the dispersion B11 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 12>
In Example 9, polyisocyanate was added to 10.2 g of tolylene diisocyanate trimer (manufactured by Mitsubishi Chemical Co., Ltd .: trade name Mytec GP750A, solid content 50 wt%, isocyanate group content 7.8 wt%). Furthermore, the number average molecular weight 2400 polypropylene glycol with one end being a butoxy group was changed to 3.9 g polypropylene glycol with a number average molecular weight 1200 having a butoxy group at one end, and the amount of n-propanol was 0.7 g. The same procedure as in Example 9 was conducted except that the amount of N, N-dimethyl-1,3-aminopropylamine was 1.2 g, polypropylene glycol was not used, and the amount of PGMEA was adjusted to a solid content concentration of 20% by weight. Thus, Dispersant Solution A12 was obtained.
Next, using the obtained dispersant solution A12, a titanium oxide dispersion B12 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B12 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 13>
In Example 9, polyisocyanate was 2.8 g of tolylene diisocyanate trimer (Mitsubishi Chemical Co., Ltd., trade name: Mytec GP750A, solid content 50 wt%, isocyanate group content 7.8 wt%). In addition, the amount of catalyst is 0.04 g, the amount of polypropylene glycol having a number average molecular weight of 2400 with one end being a butoxy group is 8.5 g, the amount of n-propanol is 0.03 g, N, N-dimethyl-1,3 -Dispersant solution A13 was obtained in the same manner as in Example 9 except that the amount of aminopropylamine was 0.3 g, polypropylene glycol was not used, and the amount of PGMEA was adjusted to a solid content concentration of 20% by weight. . Next, using the obtained dispersant solution A13, a titanium oxide dispersion B13 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B13 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 14>
In Example 9, the polyisocyanate was 6.6 g of tolylene diisocyanate trimer (Mitsubishi Chemical Corporation, trade name: Mytec GP750A, solid content 50% by weight, isocyanate group content 7.8% by weight). In addition, a polycaprolactam having a number average molecular weight of 2,400 and a number average molecular weight of 2400 having a number average molecular weight of 2400, 5.0 g, an n-propanol amount of 0.5 g, and a polypropylene glycol having a number average molecular weight of 1000 (Daicel Corporation) Made by Chemical Industry: trade name PLACEL 210) 1.1 g, N, N-dimethyl-1,3-aminopropylamine amount is 0.6 g, and the amount of PGMEA is adjusted so that the solid content concentration is 20% by weight. Except that, Dispersant Solution A14 was obtained in the same manner as Example 9. Next, using the obtained dispersant solution A14, a titanium oxide dispersion B14 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B14 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 15>
In Example 9, the polyisocyanate was 7.3 g of tolylene diisocyanate trimer (Mitsubishi Chemical Co., Ltd., trade name: Mytec GP750A, solid content 50 wt%, isocyanate group content 7.8 wt%). In addition, 5.6 g of polypropylene glycol having a number average molecular weight of 2400, one end of which is a butoxy group, 0.5 g of n-propanol, and N, N-dimethyl-1,3-aminopropylamine as amino Dispersant solution in the same manner as in Example 9, except that 0.9 g of propylimidazole (manufactured by Tokyo Chemical Industry Co., Ltd.) is used, polypropylene glycol is not used, and the amount of PGMEA is adjusted to a solid content concentration of 20% by weight. A15 was obtained. Next, using the obtained dispersant solution A15, a titanium oxide dispersion B15 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B15 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 16>
In Example 9, the polyisocyanate was 6.6 g of tolylene diisocyanate trimer (Mitsubishi Chemical Corporation, trade name: Mytec GP750A, solid content 50% by weight, isocyanate group content 7.8% by weight). In addition, the amount of catalyst is 0.04 g, the amount of polypropylene glycol having a number average molecular weight of 2400 with one end being a butoxy group is 5.0 g, the amount of n-propanol is 0.4 g, the amount of polypropylene glycol is 1.1 g, N , N-dimethyl-1,3-aminopropylamine was 0.9 g of hydroxypivalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and the amount of PGMEA was adjusted so that the solid content concentration was 20% by weight. Similarly, Dispersant Solution A16 was obtained. Next, using the obtained dispersant solution A16, a titanium oxide dispersion B16 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B16 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 17>
In Example 9, the polyisocyanate was 5.4 g of tolylene diisocyanate trimer (Mitsubishi Chemical Corporation, trade name: Mytec GP750A, solid content 50 wt%, isocyanate group content 7.8 wt%). In addition, the amount of catalyst is 0.09 g, the amount of polypropylene glycol having a number-average molecular weight of 2400 with one end being a butoxy group is 4.1 g, the amount of n-propanol is 0.3 g, the amount of polypropylene glycol is 0.9 g, Except that N, N-dimethyl-1,3-aminopropylamine is 2.0 g of monohydroxycarboxylic acid (*) and the amount of PGMEA is adjusted so that the solid content concentration is 20% by weight, the same as in Example 9. Dispersant solution A17 was obtained. Next, using the obtained dispersant solution A17, a titanium oxide dispersion B17 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B17 when a DC voltage was applied were measured. Is shown in Table 1.
The monohydroxycarboxylic acid (*) was synthesized as follows.
To a 100 ml three-necked flask, 37.5 g of polypropylene glycol was attached with a cooling tube and a nitrogen introducing tube, and heated at 150 ° C. for 10 minutes while flowing nitrogen. Next, 5.55 g of phthalic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added with stirring, and the reaction was carried out at 150 ° C. for 4 hours to obtain a product having an acid value of 50.

<Example 18>
In Example 9, the polyisocyanate was changed to 4.0 g of isophorone diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.), the catalyst amount was 0.04 g, the n-propanol amount was 6.0 g, and one end was a butoxy group. Except for adjusting the amount of PGMEA so that the solid content concentration is 20% by weight without using polypropylene glycol having a number average molecular weight of 2400, polypropylene glycol and N, N-dimethyl-1,3-aminopropylamine. In the same manner as in No. 9, a dispersant solution A18 was obtained.
Next, using the obtained dispersant solution A18, a titanium oxide dispersion B18 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B18 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 19>
In Example 9, the polyisocyanate was changed to 5.3 g of phenyl isocyanate (manufactured by Kanto Chemical Co., Inc.), the amount of n-propanol was 9.0 g, and the number average molecular weight of 2400 having a butoxy group at one end. In the same manner as in Example 9, except that the amount of PGMEA was adjusted so that the solid content concentration was 20% by weight without using polypropylene glycol, polypropylene glycol and N, N-dimethyl-1,3-aminopropylamine. Dispersant solution A19 was obtained.
Next, using the obtained dispersant solution A19, a titanium oxide dispersion B19 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B19 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 20>
In Example 9, the polyisocyanate was changed to 4.1 g of isophorone diisocyanate (Degussa, trade name: T-1890, solid content: 100% by weight, isocyanate group content: 15.4% by weight), and n-propanol was di- Changed to 2.0 g of n-butylamine, no polypropylene glycol, polypropylene glycol having a number average molecular weight of 2400 with one end being a butoxy group, N, N-dimethyl-1,3-aminopropylamine, solid content Dispersant solution A20 was obtained in the same manner as in Example 9 except that the amount of PGMEA was adjusted so that the concentration was 20% by weight. Next, using the obtained dispersant solution A20, a titanium oxide dispersion B20 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B20 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 21>
In Example 9, an adduct of trimethylolpropane of tolylene diisocyanate (produced by Nippon Polyurethane Industry Co., Ltd .: trade name Coronate L, solid content 75% by weight, isocyanate group content 13.3% by weight) 5.2 g in Example 9 In addition, n-propanol was changed to 2.0 g of di-n-butylamine, polypropylene glycol having a number average molecular weight of 2400, polypropylene glycol and N, N-dimethyl-1,3 having one end as a butoxy group. -Dispersant solution A21 was obtained in the same manner as in Example 9 except that the amount of PGMEA was adjusted so that the solid content concentration was 20% by weight without using the aminopropylamine amount.
Next, using the obtained dispersant solution A21, a titanium oxide dispersion B21 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B21 when a DC voltage was applied were measured. Is shown in Table 1.

<Example 22>
In Example 10, a dispersing agent solution A22 was obtained in the same manner as in Example 10 except that the solvent for adjusting the solid content concentration to 20% by weight was changed from PGMEA to dibenzyl ether (Kanto Chemical Co., Inc.). It was. Next, using the obtained dispersant solution A22, a titanium oxide dispersion B22 for electrophoretic display was prepared in the same manner as in Example 9, and the color characteristics of the dispersion B22 when a DC voltage was applied were measured. Is shown in Table 1.

It is a schematic diagram which shows an example of the electrophoretic display device which can use the dispersion liquid for display of this invention. It is a schematic diagram which shows the electrophoretic display device of another example which can use the dispersion liquid for display of this invention. It is a schematic diagram which shows the electrophoretic display apparatus of another example which can use the particle | grains for display of this invention. It is a schematic diagram which shows the electrophoretic display apparatus of another example which can use the particle | grains for display of this invention. It is a schematic diagram which shows the electrophoretic display apparatus of another example which can use the particle | grains for display of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 'Board | substrate 2, 2' Electrode 3 Display liquid 4 Spacer 5 Insulating film 6 Microcapsule filling layer 7 Dispersion inclusion microcapsule 8 Microcapsule and binder containing coating layer

Claims (15)

An electrophoretic display dispersion containing an electrically insulating solvent, a pigment, and a dispersing agent, comprising a compound having in its molecule a bonding chain represented by the following general formula (A) as a dispersing agent: Electrophoretic display dispersion.

(In the formula, X represents an oxygen atom or an optionally substituted nitrogen atom represented by N (R ¹ ), and R ¹ represents a hydrogen atom or an alkyl group.)   The dispersion liquid for electrophoretic display according to claim 1, wherein at least a part of the dispersant is adsorbed on the pigment.   The dispersion liquid for electrophoretic display according to claim 1 or 2, wherein titanium oxide is contained as a pigment, and the content of the titanium oxide is 5 to 50 parts by weight with respect to 100 parts by weight of the solvent.   The dispersion liquid for electrophoretic display according to claim 1 or 2, wherein carbon black is contained as a pigment, and the content of the carbon black is 0.01 to 20 parts by weight with respect to 100 parts by weight of the solvent. .   The dispersion liquid for electrophoretic display according to claim 1, wherein the solvent contains an ester solvent or an ether solvent.   6. The ester solvent according to claim 1, wherein the ester solvent is at least one ester selected from an esterified product of an alkylene glycol alkyl ether, an aliphatic carboxylic acid ester, and an aliphatic alkoxycarboxylic acid ester. The dispersion liquid for electrophoretic display as described in the item.   The compound having a bonding chain represented by the general formula (A) in a molecule is a urethane-based polymer dispersant, for electrophoretic display according to any one of claims 1 to 6. Dispersion.   The compound having a bonding chain represented by formula (A) in the dispersion in the molecule is present in an amount of 0.01 to 500 parts by weight (in terms of solid content) with respect to 100 parts by weight of the pigment in the dispersion. The dispersion liquid for electrophoretic display according to any one of claims 1 to 7.   9. The compound according to claim 1, wherein the compound having a bonding chain represented by the general formula (A) in the molecule is blended in a dispersion in a solution with an ester solvent or an ether solvent. A dispersion for electrophoretic display according to claim 1.   Electrophoretic display particles, wherein the dispersion liquid for electrophoretic display according to any one of claims 1 to 9 is enclosed in a microcapsule.   A pair of base materials for display each provided with an electrode on one side of a substrate are arranged to face each other through a spacer to form a space, and electrophoresis is performed according to any one of claims 1 to 9 in the space. An electrophoretic display device filled with a display dispersion, wherein at least one of the pair of display substrates is provided with a transparent electrode on one side of a transparent substrate.   The dispersion liquid for electrophoretic display according to any one of claims 1 to 9, wherein a space is formed by facing an insulating film through a spacer on a display base material provided with an electrode on one side of a substrate, and the space is formed in the space. And at least one of a display substrate and an insulating film is transparent.   A pair of base materials for display each provided with an electrode on one side of a substrate are formed so that the electrode surfaces face each other to form a space, and the space is filled with the electrophoretic display particles according to claim 10, and the pair of base materials An electrophoretic display device, wherein at least one of the substrates for display is provided with a transparent electrode on one side of a transparent substrate.   An insulating film is opposed to a display base material provided with electrodes on one side of the substrate to form a space, and the electrophoretic display particles according to claim 10 are filled in the space, and the display base material and the insulating film An electrophoretic display device characterized in that at least one of them is transparent. Electrophoresis characterized in that a coating layer containing particles for electrophoretic display according to claim 10 and a binder is formed on a display substrate having a transparent or opaque electrode on one side of a transparent or opaque substrate. Display device.

Images