JP2010132809A - Charge control material, display particle dispersion, display medium and display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charge control material which imparts stable dispersibility and charging characteristics to display particles with a smaller amount of addition as compared to other charge control materials, and a display particle dispersion, a display medium and a display using the charge control material. <P>SOLUTION: The charge control material is at least one selected from a first reaction adduct of a reactive polymer having a reactive functional group and a reactive silicone compound having a reactive functional group which takes part in an addition reaction to the reactive functional group of the reactive polymer, and a second reaction adduct of a reactive silicone compound having a reactive functional group and at least one of an amine compound, an alkyl halide compound and a polybasic acid each of which takes part in an addition reaction to the reactive functional group of the reactive silicone compound. The display particle dispersion, the display medium and the display using the charge control material are also provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charge control material, a display particle dispersion, a display medium, and a display device.

  An electrophoretic display medium has been actively studied as a display having a memory property. In this display method, an electrophoretic material in which charged display particles (electrophoretic particles) are dispersed in a liquid is used, and the electrophoretic particles are placed in the cell by applying an electric field (two electrophoretic substrates are stacked between the electrophoretic materials). The display can be performed by alternately moving to the viewing surface and the back surface of the structure in which is enclosed.

  In the present technology, the electrophoretic material is an important element, and various technical developments have been made. In addition, as a liquid for dispersing particles, a material having low volatility and high safety as a chemical substance is desired. Examples of such highly safe liquids include paraffinic hydrocarbon solvents that are petroleum-derived high-boiling components (exon products such as Isopar-based materials manufactured by Exxon), silicone oil, fluorine-based liquids, etc. Therefore, a material that is stably dispersed in such a liquid and has excellent chargeability and electrophoretic properties is required. In particular, silicone oil is useful because it has low volatility and flammability and high safety.

However, at present, a material system that is stably dispersed in silicone oil and has stable charging characteristics is not well known. As a prior art, for example, a technique using a silicone-based charge control polymer dispersant has been proposed in Patent Documents 1 and 2, and a configuration containing a charge adjusting agent as electrophoretic particles dispersed in silicone oil is disclosed. ing.
Japanese Patent No. 3936588 JP 2002-212423 A

  An object of the present application is to provide a charge control material that imparts stable dispersibility and charge characteristics to display particles with a small addition amount compared to other types of charge control materials.

  The above problem is solved by the following means. That is,

The invention according to claim 1
A first reactive adduct of a reactive polymer having a reactive functional group and a reactive silicone compound having a reactive functional group that undergoes an addition reaction to the reactive functional group of the reactive polymer, and the reactivity From a reactive silicone compound having a functional group and a second reaction adduct of at least one of an amine compound, a halogenated alkyl compound and a polybasic acid that undergo an addition reaction with respect to the reactive functional group of the reactive silicone compound. A charge control material that is at least one selected.

The invention according to claim 2
The first reactive adduct is a reactive polymer having at least a monomer unit represented by the following general formula (1) and a reactive silicone system represented by the general formula (1-A) and the general formula (1-B). The charge control material according to claim 1, wherein the charge control material is an addition reaction product with at least one compound.

The invention according to claim 3
The charge control material according to claim 1, wherein the first reaction adduct is a polymer compound containing at least a structural unit represented by the following general formula (11).

(In the general formula (11), R ¹ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a halogen group. R ² represents the following structural formula (11-A) or structural formula (11- B represents a group represented by B), R ³ represents a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, R ⁴ represents an alkyl group having 1 to 10 carbon atoms, and X represents —COOCH ₂ CH. Represents a group represented by (OH)-, and p represents 0 or 1.)

(In the structural formula (11-A) or the structural formula (11-B), R ⁵ represents an alkylene group having 3 to 10 carbon atoms. R ⁶ is an alkyl group having 1 to 10 carbon atoms, or Represents an aminoalkyl group having 1 to 10 carbon atoms, and n1 represents an integer of 1 to 1000.)

The invention according to claim 4
The charge control material according to claim 1, wherein the first reaction adduct is a polymer compound composed only of the structural unit represented by the general formula (11).

The invention according to claim 5
The charge control material according to claim 1, wherein the reactive silicone compound having a reactive functional group in the second reaction adduct is a reactive silicone compound represented by the following general formula (2).

The invention according to claim 6
The charge control material according to claim 1, wherein the second reaction adduct is a polymer compound containing a structural unit represented by the following general formula (22).

(In the general formula (22), X represents a group represented by the following structural formula (22-A) or structural formula (22-B).)

(In the structural formula (22-A) or the structural formula (22-B), R and R ³ each independently represents an alkylene group having 1 to 10 carbon atoms. R ¹ , R ² , R ⁴ , and R ⁵ represents each independently an alkyl group having 1 to 18 carbon atoms or an aromatic group.)

The invention according to claim 7 provides:
The charge control material according to claim 1, wherein the second reaction adduct is a compound represented by the following general formula (22-1).

(In the general formula (22-1), X represents a group represented by the structural formula (22-A) or the structural formula (22-B). M represents an integer of 1 to 1000. n represents 1 represents an integer of 1 or more.

The invention according to claim 8 provides:
A group of particles including display particles that move in response to an electric field;
Silicone oil as a dispersion medium for dispersing the particles;
The charge control material according to claim 1, which is contained in the dispersion medium,
A particle dispersion for display, comprising:

The invention according to claim 9 is:
A pair of substrates, at least one of which is translucent,
The display dispersion liquid according to claim 8 enclosed between the pair of substrates;
A display medium comprising:

The invention according to claim 10 is:
A pair of electrodes;
The display dispersion liquid according to claim 8 enclosed between the pair of electrodes,
A display medium comprising:

The invention according to claim 11 is:
A display medium according to claim 9 or 10,
Voltage applying means for applying a voltage between the pair of substrates of the display medium;
A display device comprising:

According to the first aspect of the present invention, there is provided a charge control material that imparts stable dispersibility and charge characteristics to display particles with a small addition amount compared to other types of charge control materials.
According to the second aspect of the present invention, there is provided a charge control material that imparts stable dispersibility and charge characteristics to display particles with a small addition amount compared to other types of charge control materials.
According to the third aspect of the present invention, there is provided a charge control material that imparts stable dispersibility and charge characteristics to display particles with a small addition amount compared to other types of charge control materials.
According to the fourth aspect of the present invention, there is provided a charge control material that imparts stable dispersibility and charge characteristics to display particles with a small addition amount compared to other types of charge control materials.
According to the fifth aspect of the present invention, there is provided a charge control material that imparts stable dispersibility and charge characteristics to display particles with a small addition amount compared to other types of charge control materials.
According to the sixth aspect of the present invention, there is provided a charge control material that imparts stable dispersibility and charge characteristics to display particles with a small addition amount compared to other types of charge control materials.
According to the seventh aspect of the present invention, there is provided a charge control material that imparts stable dispersibility and charge characteristics to display particles with a small addition amount compared to other types of charge control materials.

According to the eighth aspect of the present invention, display particles including display particles that are provided with stable dispersibility and charging characteristics with a small amount of charge control material compared to the case where other types of charge control materials are used. A dispersion is provided.
According to the ninth aspect of the present invention, there is provided a display medium capable of displaying repeatedly and stably with a small amount of charge control material compared to the case of using other types of charge control materials.
According to the tenth aspect of the present invention, there is provided a display device capable of displaying repeatedly and stably with a small amount of charge control material compared to the case of using other types of charge control materials.
According to the eleventh aspect of the present invention, there is provided a display device capable of displaying repeatedly and stably with a small amount of charge control material compared to the case of using other types of charge control materials.

  Hereinafter, embodiments of the present invention will be described.

(Charge control material, particle dispersion for display)
The display particle dispersion according to the present embodiment includes a particle group including display particles that move according to an electric field, silicone oil as a dispersion medium for dispersing the particle group, and a specific particle included in the dispersion medium. A charge control material. In the present embodiment, the specific charge control material imparts stable dispersibility and charge characteristics to the display particles with a small addition amount compared to other types of charge control materials. Here, the charging characteristics indicate the charge polarity and charge amount of the particles. In this embodiment, fluctuations in the charge polarity and charge amount are suppressed and stabilized. Then, by applying the display particle dispersion to a display medium and a display device, the display can be repeatedly and stably displayed with a small amount of charge control material compared to the case of using another type of charge control material.

A specific charge control material will be described. Specific charge control materials include at least one of the following addition reactants.
1) First reaction adduct between a reactive polymer having a reactive functional group and a reactive silicone compound having a reactive functional group that undergoes an addition reaction to the reactive functional group of the reactive polymer 2) Reaction Second reactive adduct of a reactive silicone compound having a reactive functional group and at least one of an amine compound and a dibasic acid that undergo an addition reaction with respect to the reactive functional group of the reactive silicone compound

  First, the first reaction adduct will be described. The first reaction adduct is a reaction adduct of a reactive polymer and a silicone compound. That is, the first reaction adduct is obtained by an addition reaction between a reactive polymer and a silicone compound.

  The reactive polymer has a reactive functional group that undergoes an addition reaction with the reactive functional group of the reactive silicone compound. Preferred examples of the reactive functional group include an epoxy group, an isocyanate group, a hydroxyl group, an acid group, and an amino group.

  Examples of the reactive polymer include a homopolymer of a reactive monomer having a reactive functional group, a monomer having a reactive functional group, and another monomer (a monomer having no reactive functional group). And a copolymer thereof.

Examples of reactive monomers include glycidyl (meth) acrylate, isocyanate monomer (Showa Denko: Karenz AOI, Karenz MOI), hydroxyalkyl (meth) acrylate (meth) acrylic acid or salts thereof, maleic acid, (meth) acrylamide- Examples thereof include 2-methylpropanesulfonic acid or a salt thereof, vinylsulfonic acid or a salt thereof, (meth) acrylamide, vinylamine, vinyl acetate (converted to a vinyl alcohol monomer unit after hydrolysis).

  Other monomers include, for example, (meth) acrylic acid alkylate or derivatives thereof, styrene or derivatives thereof, vinyl pyrrolidone, monomers having ethylene oxide units (for example, alkyloxyoligoethylene such as tetraethylene glycol monomethyl ether (meth) acrylate) Preferable examples include glycol (meth) acrylate and polyethylene glycol one-terminal (meth) acrylate.

  Here, the reactive polymer preferably contains an acid group or an amino group in order to impart charging characteristics to the display particles. These acid groups or amino groups may be used together with the reactive functional group in the reactive monomer, or separately, the monomer containing the acid group or amino group may be used as the reactive monomer. It may be copolymerized with a monomer and introduced into a reactive polymer. Examples of the monomer containing an acid group or amino group as the other monomer include N-alkyl-substituted alkyl (meth) acrylate (for example, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, etc.). Preferably mentioned.

  Here, the copolymerization ratio (mass ratio) of the reactive monomer and the other monomer is preferably 10:90 to 100: 0, and more preferably 20:80 to 100: 0. is there.

  On the other hand, the reactive silicone compound has a reactive functional group that undergoes an addition reaction with respect to the reactive functional group of the reactive polymer. Examples of the reactive functional group include an epoxy group, an amino group, a hydroxyl group, and a carboxyl group. The reactive silicone compound preferably has the reactive functional group at one end.

  Specifically, as the reactive silicone compound, for example, a silicone compound having an epoxy group (for example, X-22-173DX manufactured by Shin-Etsu Silicone Co., Ltd.), a silicone compound having an amino group (for example, Momentive Performance Materials: TSF4700, TSF4701, etc.), silicone-based compounds having a hydroxyl group (for example, X-22-170BX, X-22-170DX, X-22-176DX, X-22-176F manufactured by Shin-Etsu Silicone) ), A silicone-based compound having a carboxyl group (for example, X-22-3710 manufactured by Shin-Etsu Silicone Co., Ltd.).

  In the first reaction adduct, the ratio of the reactive silicone compound to addition reaction with respect to the reactive polymer is 10% to 90% with respect to the number of reactive functional groups possessed by the reactive polymer. The range of is preferable. More preferably, it is in the range of 20% to 90%. It is not necessary to undergo an addition reaction to all 100% of the functional groups possessed by the reactive polymer, and it is desirable to react to the extent that it becomes soluble in silicone oil. Expressed in another definition, the amount of reactive silicone contained in the produced adduct is preferably 30% by mass or more because it is soluble in silicone, and more preferably 40% by mass or more.

  As the first reaction adduct, in particular, a reactive polymer having at least a monomer unit represented by the following general formula (1) and a reaction represented by the general formula (1-A) and the general formula (1-B) It is desirable that it is an addition reaction product with at least one of the functional silicone compounds. The compound imparts stable dispersibility and charging characteristics to the display particles with a small addition amount compared to other types of charge control materials.

  The first reaction adduct is particularly preferably a polymer compound containing a structural unit represented by the following general formula (1). The polymer compound imparts stable dispersibility and charging characteristics to the display particles with a small addition amount compared to other types of charge control materials.

The charge control material according to claim 1, wherein the first reaction adduct is a polymer compound containing at least a structural unit represented by the following general formula (11).

In General Formula (11), R ¹ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a halogen group. R ² represents a group represented by the following structural formula (2-A) or structural formula (2-B). R ³ represents a hydrogen atom or an alkyl group having 1 to 30 carbon atoms. R ⁴ represents an alkyl group having 1 to 10 carbon atoms. X represents a group represented by —COOCH ₂ CH (OH) —. p represents 0 or 1. )

  In general formula (11), the alkyl group having 1 to 10 carbon atoms represented by each symbol may be linear, branched, or cyclic. For example, methyl group, ethyl group, isopropyl group, butyl Group, isopentyl group, amyl group, hexyl group, cyclohexyl group, octyl group, ethylhexyl group, isononyl group, decyl group and the like. The alkyl group having 1 to 10 carbon atoms is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms.

  In general formula (11), the alkyl group having 1 to 30 carbon atoms represented by each symbol may be linear, branched, or cyclic. For example, methyl group, ethyl group, isopropyl group, butyl Group, isopentyl group, amyl group, hexyl group, cyclohexyl group, octyl group, ethylhexyl group, isononyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group and the like. The alkyl group having 1 to 30 carbon atoms is preferably an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 12 carbon atoms.

p represents 0 or 1, and when 0, it represents a tertiary amino group structure (—NR ₂ R ₃ ), and when 1 represents a quaternary amino group structure ((—N ⁺ R ₂ R ₃ R ₄ ). Is meant to represent

In Structural Formula (11-A) or Structural Formula (11-B), R ⁵ represents an alkylene group having 3 to 10 carbon atoms. R ⁶ represents an alkyl group having 1 to 10 carbon atoms or an aminoalkyl group having 1 to 10 carbon atoms. n1 represents an integer of 1 or more and 1000. )

  In the structural formula (11-A) or the structural formula (11-B), examples of the aminoalkyl group having 1 to 10 carbon atoms include aminoethyl group, aminopropyl group, aminobutyl group, aminopentyl group, and aminohexyl. Groups and the like. The aminoalkyl group having 1 to 10 carbon atoms is preferably an aminoalkyl group having 1 to 8 carbon atoms, more preferably an aminoalkyl group having 1 to 5 carbon atoms.

  In Structural Formula (11-A) or Structural Formula (11-B), an alkyl group having 1 to 10 carbon atoms and an alkylene group having 1 to 10 carbon atoms represented by each symbol are represented by General Formula (11). It is synonymous with the C1-C10 alkyl group and C1-C10 alkylene group which each code | symbol represents.

  In Structural Formula (11-A) or Structural Formula (11-B), n1 represents an integer of 1 to 1000, preferably 10 to 1000, and more preferably 10 to 500.

As the compound containing the structural unit represented by the general formula (11), in particular,
R ¹ represents a methyl group or a hydrogen atom,
R ² represents a group represented by the structural formula (11-A) or the structural formula (11-B),
R ³ represents a hydrogen atom,
X represents a —COOCH ₂ CH (OH) — group,
p indicates 0 (ie no R ⁴ ),
And in Structural Formula (11-A) or Structural Formula (11-B),
R ⁵ represents a propylene group,
R ⁶ represents a methyl group,
n1 is preferably a compound representing an integer of 1 or more and 100.

  The compound containing the structural unit represented by the general formula (11) (first reaction adduct) is preferably a compound comprising only the structural unit represented by the general formula (11). The compound containing the structural unit shown and other structural units (for example, the polymerization unit of the said other monomer) may be sufficient. However, the structural unit represented by the general formula (11) is preferably contained in an amount of 10% by weight or more. The polymer compound containing the structural unit represented by the general formula (11) imparts stable dispersibility and charging characteristics to the display particles as compared with other types of charge control materials.

  Next, the second reaction adduct will be described. The second reaction adduct is a reaction adduct of a reactive silicone compound and at least one of an amine compound, an alkyl halide compound and a polybasic acid. That is, the second reaction adduct is obtained by an addition reaction between a reactive silicone compound and at least one of an amine compound, an alkyl halide compound and a polybasic acid.

The reactive silicone compound has a reactive functional group on which at least one of an amine compound and a polybasic acid undergoes an addition reaction. Examples of the reactive functional group include a primary amino group, a secondary amino group, a tertiary amino group, and an epoxy group. The reactive silicone compound has a dimethyl silicone chain (—Si (CH ₃ ) ₂ O—) in which a terminal functional group or a methyl group (—CH ₃ ) is introduced by substitution of the reactive functional group. Good.

Specifically as a reactive silicone type compound, a reactive dimethyl silicone type compound is mentioned suitably, for example,
Silicone compounds having a primary amino group (for example, KF-8010, XX-22-161A, XX-22-161B, X-22-1660B-3, KF-8008, KF-8012, KF manufactured by Shin-Etsu Chemical Co., Ltd.) -857, KF-8001, KF-862, X-22-9192, KF-858, etc.) Silicone compounds having primary and secondary amino groups (for example, KF-393, KF- manufactured by Shin-Etsu Chemical Co., Ltd.) 859, KF-860, KF-861, KF-867, KF-869, KF-880, KF-8002, KF-8004, KF-8005, KF-858, KF-864, KF-865, KF-868, KF-8003 etc.) or a silicone compound having an epoxy group (for example, KF-105, X22-163A, X-22- manufactured by Shin-Etsu Chemical Co., Ltd.) 63B, X-22-163C, KF-1001, KF-101, X-22-2000, X-22-169AS, XX-22-169B, KF-102, X-22-9002, X-22-2046, etc. ).

  On the other hand, an amine compound, a halogenated alkyl compound, and a polybasic acid are compounds that undergo an addition reaction with the reactive functional group of the reactive silicone compound.

Examples of the amine compound include dimethylaminoethylamine, dimethylaminopropylamine, diethylaminoethylamine, diethylaminopropylamine and the like.
Examples of the halogenated alkyl compound include chlorine, iodine, or bromine substituted compounds having an alkyl group having 1 to 18 carbon atoms (for example, methyl bromide, ethyl bromide, propyl bromide, butyl bromide, hexyl bromide, Octyl bromide, decyl bromide, dodecyl bromide, octadecyl bromide, methyl iodide, ethyl iodide, propyl iodide, butyl iodide, hexyl iodide, octyl iodide, decyl iodide, dodecyl iodide, iodide Octadecyl and the like).

  Polybasic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, isocitric acid, 1,2,4-butanetricarboxylic acid, And di- or tricarboxylic acid.

  In the second reaction adduct, the range of the ratio of the addition reaction of at least one of an amine compound, an alkyl halide compound and a polybasic acid with respect to the addition reactive group in the reactive silicone compound (molar ratio reactive silicone). As the system compound: at least one of the amine compound, the alkyl halide compound, and the polybasic acid, 1: 0.1 to 4: 4 is desirable, and more desirably 1: 0.2 to 1: 4. In addition, about addition reaction, it is not necessary to substitute for all the addition reaction groups in reactive silicone, and it may be in the above-mentioned range.

  Here, the reactive silicone compound having a reactive functional group in the second reaction adduct is preferably a reactive silicone compound represented by the following general formula (2). By applying the compound, stable dispersibility and charging characteristics are imparted to the display particles with a small addition amount compared to other types of charge control materials.

  Here, in general formula (2), m preferably represents an integer of 1 to 500, and n preferably represents an integer of 1 to 500. The ratio between m and n is preferably 99: 1 to 10:90, more preferably 98: 2 to 20:80.

  The second reaction adduct is particularly preferably a compound containing a structural unit represented by the following general formula (22). The compound imparts stable dispersibility and charging characteristics to the display particles with a small addition amount compared to other types of charge control materials.

  In General Formula (22), X represents a group represented by the following Structural Formula (22-A) or Structural Formula (22-B). )

In the structural formula (22-A) or the structural formula (22-B), R and R ³ each independently represents an alkylene group having 1 to 10 carbon atoms. R ¹ , R ² , R ⁴ , and R ⁵ each independently represents an alkyl group having 1 to 18 carbon atoms, or an aromatic group.

  In the structural formula (22-A) or the structural formula (22-B), the alkyl group having 1 to 18 carbon atoms represented by each symbol may be linear, branched, or cyclic. Examples thereof include a methyl group, an ethyl group, an isopropyl group, a butyl group, an isopentyl group, an amyl group, a hexyl group, a cyclohexyl group, an octyl group, an ethylhexyl group, an isononyl group, a decyl group, a dodecyl group, and an octadecyl group. The alkyl group having 1 to 18 carbon atoms is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms.

  In the structural formula (22-A) or the structural formula (22-B), the alkylene group having 1 to 10 carbon atoms represented by each symbol may be either linear or branched. For example, for example, Examples include an ethylene group, a propylene group, a butylene group, an amylene group, a hexylene group, and a trimethylene group. The alkylene group having 1 to 10 carbon atoms is preferably an alkylene group having 1 to 6 carbon atoms, more preferably an alkylene group having 3 to 6 carbon atoms.

  In the structural formula (2-A) or the structural formula (2-B), examples of the aromatic group represented by each symbol include a phenyl group and a substituted phenyl group.

In the structural formula (22-A) or the structural formula (22-B), in particular,
R represents a propylene group,
R ³ represents an ethylene group or a propylene group,
R ¹ represents an alkyl group having 1 to 12 carbon atoms,
R ² represents an alkyl group having 1 to 12 carbon atoms,
R ⁴ represents an alkyl group having 1 to 12 carbon atoms,
R ⁵ preferably represents an alkyl group having 1 to 12 carbon atoms.

  The compound (second adduct) containing the structural unit represented by the general formula (22) is particularly preferably a compound represented by the following general formula (22-1).

  In General Formula (22-1), X represents a group represented by Structural Formula (22-A) or Structural Formula (22-B). m represents an integer of 1 or more and 1000. n represents an integer of 1 to 1000. ) Here, m preferably represents an integer of 1 or more and 500, and n preferably represents an integer of 1 or more and 500. The ratio between m and n is preferably 99: 1 to 10:90, more preferably 98: 2 to 20:80.

The specific charge control material described above is a charge control material that is soluble in the dispersion medium (silicone oil). Here, the term “soluble” means that at 25 ° C., the charge control material dissolves in an amount of 10 g / L or more in the dispersion medium (silicone oil).
The content of the specific charge control material is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.01% by mass or more and 5% by mass with respect to the dispersion medium (eg, silicone oil). More preferably, it is 0.01 mass% or more and 3 mass% or less.

  The specific charge control material may be used in combination with other charge control materials. Other charge control materials include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorine-based surfactants, silicone-based surfactants, silicone-based cationic compounds, and silicone-based surfactants. Anionic compounds, metal soaps, alkyl phosphate esters, succinimides and the like can be mentioned. These are used in combination as long as the function of the specific charge control material is not inhibited.

  Next, the display particles will be described. The display particles preferably include a polymer having a charged group, a colorant, and, if necessary, other compounding materials. The display particles are not limited to this, and for example, a pigment (pigment particles) whose surface is modified with a compound having a charging group (for example, a polymer having a charging group or a monomer having a charging group) is used. May be.

  The polymer having a charged group is a polymer having, for example, a cationic group or an anionic group as a charged group. Examples of the cationic group as the charging group include an amino group and a quaternary ammonium group (including salts of these groups), and positively charged polarity is imparted to the particles by the cationic group. On the other hand, examples of the anionic group as the charging group include a phenol group, a carboxyl group, a carboxylate group, a sulfonate group, a sulfonate group, a phosphate group, a phosphate group, and a tetraphenylboron group (these groups). The anionic group imparts negatively charged polarity to the particles.

  Specifically, the polymer having a charging group may be, for example, a homopolymer of a monomer having a charging group, or a monomer having a charging group and another monomer (charging group). And monomers having no monomer).

  Examples of the monomer having a charging group include a monomer having a cationic group (hereinafter referred to as a cationic monomer) and a monomer having an anionic group (hereinafter referred to as an anionic monomer).

Examples of the cationic monomer include the following. Specifically, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-hydroxyethylaminoethyl (meta) ) Acrylate, N-ethylaminoethyl (meth) acrylate, N-octyl-N-ethylaminoethyl (meth) acrylate, N, N-dihexylaminoethyl (meth) acrylate and other aliphatic amino groups (meth) Acrylates, aromatic substituted ethylene monomers having nitrogen-containing groups such as dimethylaminostyrene, diethylaminostyrene, dimethylaminomethylstyrene, dioctylaminostyrene,
Vinyl-N-ethyl-N-phenylaminoethyl ether, vinyl-N-butyl-N-phenylaminoethyl ether, triethanolamine divinyl ether, vinyl diphenylaminoethyl ether, N-vinylhydroxyethylbenzamide, m-aminophenyl vinyl ether Nitrogen-containing vinyl ether monomers such as vinylamine, pyrroles such as N-vinylpyrrole, pyrrolines such as N-vinyl-2-pyrroline and N-vinyl-3-pyrroline, N-vinylpyrrolidine, vinylpyrrolidineaminoe Ether, pyrrolidines such as N-vinyl-2-pyrrolidone, imidazoles such as N-vinyl-2-methylimidazole, imidazolines such as N-vinylimidazoline, indoles such as N-vinylindole, N-vinylindoline, etc. Inn Phosphorus, N-vinylcarbazole, carbazoles such as 3,6-dibromo-N-vinylcarbazole, pyridines such as 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyrazine, (meth) acrylic piperidine , Piperidines such as N-vinylpiperidone and N-vinylpiperazine, quinolines such as 2-vinylquinoline and 4-vinylquinoline, pyrazoles such as N-vinylpyrazole and N-vinylpyrazoline, oxazoles such as 2-vinyloxazole, Oxazines such as 4-vinyloxazine and morpholinoethyl (meth) acrylate are exemplified.
Moreover, as a particularly preferable cationic monomer from versatility, (meth) acrylates having an aliphatic amino group such as N, N-dimethylaminoethyl (meth) acrylate and N, N-diethylaminoethyl (meth) acrylate In particular, it is preferable to use a quaternary ammonium salt structure before or after polymerization. Quaternary ammonium chloride can be obtained by reacting the above compound with alkyl halides or tosylate esters.

On the other hand, as an anionic monomer, the following are mentioned, for example.
Specifically, among the anionic monomers, carboxylic acid monomers include (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, or anhydrides thereof and monoalkyl esters thereof. And vinyl ethers having a carboxyl group such as carboxyethyl vinyl ether and carboxypropyl vinyl ether.
Examples of the sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) click acid ester, bis- (3-sulfopropyl) -itaconic acid ester, and salts thereof. There is. In addition, there are sulfuric acid monoesters of 2-hydroxyethyl (meth) acrylic acid and salts thereof.
Examples of phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, acid phosphoxyethyl (meth) acrylate, acid phosphoxypropyl (meth) acrylate, bis (methacryloxyethyl) phosphate, diphenyl-2-methacryloyloxyethyl phosphate, diphenyl There are 2-acryloyloxyethyl phosphate, dibutyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dioctyl-2- (meth) acryloyloxyethyl phosphate, and the like.
Preferable anionic monomers are those having (meth) acrylic acid or sulfonic acid, and more preferably those having a structure that becomes an ammonium salt before or after polymerization. Ammonium salts can be prepared by reacting with tertiary amines or quaternary ammonium hydroxides.

  Other monomers include nonionic monomers (nonionic monomers) such as (meth) acrylonitrile, (meth) acrylic acid alkyl esters, (meth) acrylamide, ethylene, propylene. , Butadiene, isoprene, isobutylene, N-dialkyl substituted (meth) acrylamide, styrene, vinyl carbazole, styrene, styrene derivatives, polyethylene glycol mono (meth) acrylate, vinyl chloride, vinylidene chloride, isoprene, butadiene, vinyl pyrrolidone, hydroxyethyl ( Examples include meth) acrylate and hydroxybutyl (meth) acrylate.

  Here, the copolymerization ratio between the monomer having a charging group and another monomer is appropriately changed according to the charge amount of the desired particles. Usually, the copolymerization ratio of the monomer having a charged group and another monomer is selected in the range of 1: 100 to 100: 0 in terms of the molar ratio.

  The weight average molecular weight of the polymer having a charging group is preferably from 1,000 to 1,000,000, more preferably from 10,000 to 200,000.

  Next, the colorant will be described. Examples of the colorant include organic or inorganic pigments, oil-soluble dyes, etc., for example, magnetic powders such as magnetite and ferrite, carbon black, titanium oxide, magnesium oxide, zinc oxide, phthalocyanine copper-based cyan colorants, azo Known colorants such as a yellow color material, an azo magenta color material, a quinacridone magenta color material, a red color material, a green color material, and a blue color material can be used. Specifically, examples of the colorant include aniline blue, calcoyl blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. Blue 15: 1, C.I. I. Pigment Blue 15: 3, etc. are exemplified as typical examples.

  The blending amount of the colorant is desirably 10% by mass or more and 99% by mass or less, and desirably 30% by mass or more and 99% by mass or less with respect to the polymer having a charging group.

Next, other compounding materials will be described. Examples of other compounding materials include a charge control material and a magnetic material.
As the charge control material, known materials used for electrophotographic toner materials can be used. For example, cetylpyridyl chloride, BONTRON P-51, BONTRON P-53, BONTRON E-84, BONTRON E-81 (above, Quaternary ammonium salts such as Orient Chemical Industry Co., Ltd., salicylic acid metal complexes, phenol condensates, tetraphenyl compounds, metal oxide fine particles, and metal oxide fine particles surface-treated with various coupling agents. .

As the magnetic material, a color-coated inorganic magnetic material or organic magnetic material is used as necessary. Further, a transparent magnetic material, in particular, a transparent organic magnetic material does not hinder the color development of the color pigment, and the specific gravity is smaller than that of the inorganic magnetic material, and is more desirable.
As a colored magnetic material (color-coated material), for example, a small-diameter colored magnetic powder described in JP-A-2003-131420 can be used. A material provided with magnetic particles serving as nuclei and a colored layer laminated on the surface of the magnetic particles is used. The colored layer may be appropriately selected, for example, coloring the magnetic powder opaque with a pigment or the like, but it is preferable to use a light interference thin film, for example. This optical interference thin film is a thin film having a thickness equivalent to the wavelength of light made of an achromatic material such as SiO ₂ or TiO ₂ and selectively reflects the wavelength of light by optical interference in the thin film. It is.

Next, the display particle dispersion (electrophoretic composition) according to the present embodiment will be described. The display particle dispersion according to the present embodiment includes a particle group including display particles that move according to an electric field;
The dispersion medium as a dispersion medium for dispersing the particle group, and the charge control material according to the above-described embodiment included in the dispersion medium. As the dispersion medium, silicone oil, modified silicone oil, paraffin oil, various isopars or a mixed solution thereof can be used.

  The concentration of the display particles in this dispersion (concentration in the display particle dispersion) is variously selected depending on the display characteristics, response characteristics, or use thereof, but is selected in the range of 0.1 mass% to 30 mass%. It is desirable that When mixing multi-particles having different colors, the total amount of the particles is preferably within this range. If the amount is less than 0.1% by mass, the display density becomes insufficient. If the amount is more than 30% by mass, the display speed may become slow or aggregation may occur.

  Various charge control materials are selected depending on the combination with display particles. For example, when the display particles are negatively charged particles having an anionic group such as an acid group or a salt of an acid group, the charge control material added thereto may be a reaction adduct having an amino group or an ammonium group. desirable. On the other hand, when the display particles are positively charged particles having a cationic group such as an amino group or an ammonium group, the charge control material added thereto is preferably a reaction adduct having an acid group. Thus, by combining display particles having different characteristics and a charge control material, stable charge polarity and charge stability can be obtained.

  It is also preferable that the display particles are obtained by mixing a plurality of types of particles having different colors, charge polarities, and charge amounts to obtain a color display. For example, a plurality of types of display particles having different charging polarities can be obtained, for example, by changing the charging group of a polymer having a charging group described later.

  The display particle dispersion according to this embodiment is used for an electrophoretic display medium, an electrophoretic light control medium (light control element), a liquid toner of a liquid developing electrophotographic system, and the like. In addition, as an electrophoretic display medium and an electrophoretic light control medium (light control element), a known method of moving particles in a direction perpendicular to the electrode (substrate) surface is different from the horizontal direction. There is a method of moving to (so-called in-plane type element), or a hybrid element combining these.

(Display medium, display device)
Hereinafter, examples of the display medium and the display device according to the embodiment will be described.

-First embodiment-
First, the first embodiment will be described. FIG. 1 is a schematic configuration diagram of a display device according to the first embodiment. FIG. 2 is an explanatory diagram schematically illustrating a movement mode of the particle group when a voltage is applied between the substrates of the display medium of the display device according to the first embodiment.

  The display device 10 according to the first embodiment includes the display particles according to the above embodiment, the dispersion medium, and a specific charge control material as a particle dispersion liquid including the dispersion medium 50 and the particle group 34 of the display medium 12. In this embodiment, the display particle dispersion according to this embodiment is applied.

  As shown in FIG. 1, the display device 10 according to the first embodiment includes a display medium 12, a voltage application unit 16 that applies a voltage to the display medium 12, and a control unit 18.

  The display medium 12 includes a display substrate 20 that serves as an image display surface, a rear substrate 22 that faces the display substrate 20 with a gap, and holds the substrates at a predetermined interval, and between the display substrate 20 and the rear substrate 22. The gap member 24 is configured to include a plurality of cells, a particle group 34 enclosed in each cell, and a large-diameter colored particle group 36 having optical reflection characteristics different from those of the particle group 34.

  The cell indicates a region surrounded by the display substrate 20, the back substrate 22, and the gap member 24. A dispersion medium 50 is enclosed in this cell. The particle group 34 (described in detail later) is composed of a plurality of particles. The particle group 34 is dispersed in the dispersion medium 50 and passes between the display substrate 20 and the back substrate 22 according to the electric field strength formed in the cell. It moves through the gap of the large-diameter colored particle group 36.

  In the present embodiment, it is assumed that the particle group 34 enclosed in one cell has a predetermined color and is prepared in advance by being charged positively or negatively.

  In addition, the gap member 24 is provided so as to correspond to each pixel when an image is displayed on the display medium 12, and cells are formed so as to correspond to each pixel, so that the display medium 12 can display each pixel. You may comprise so that it may become possible.

  Further, in the present embodiment, in order to simplify the description, the present embodiment will be described using a diagram focusing on one cell. Hereinafter, each configuration will be described in detail.

  First, the pair of substrates will be described. The display substrate 20 has a configuration in which a surface electrode 40 and a surface layer 42 are sequentially laminated on a support substrate 38. The back substrate 22 has a configuration in which a back electrode 46 and a surface layer 48 are laminated on a support substrate 44.

  The display substrate 20 or both the display substrate 20 and the back substrate 22 are translucent. Here, the translucency in the present embodiment indicates that the visible light transmittance is 60% or more.

  Examples of the support substrate 38 and the support substrate 44 include glass and plastics such as polyethylene terephthalate resin, polycarbonate resin, acrylic resin, polyimide resin, polyester resin, epoxy resin, and polyethersulfone resin.

  For the surface electrode 40 and the back electrode 46, oxides such as indium, tin, cadmium and antimon, composite oxides such as ITO, metals such as gold, silver, copper and nickel, organic materials such as polypyrrole and polythiophene are used. Is done. These can be used as a single layer film, a mixed film or a composite film, and are formed by vapor deposition, sputtering, coating, or the like. Moreover, the thickness is normally 100 to 2000 mm according to the vapor deposition method and the sputtering method. The back electrode 46 and the front electrode 40 may be formed in a desired pattern, for example, a matrix shape or a stripe shape enabling a passive matrix drive, by a conventionally known means such as etching of a conventional liquid crystal display medium or a printed circuit board. Good.

  Further, the surface electrode 40 may be embedded in the support substrate 38. Further, the back electrode 46 may be embedded in the support substrate 44. In this case, the materials of the support substrate 38 and the support substrate 44 are selected according to the composition of each particle of the particle group 34 and the like.

  The back electrode 46 and the surface electrode 40 may be separated from the display substrate 20 and the back substrate 22 and disposed outside the display medium 12.

  In the above description, the case where both the display substrate 20 and the back substrate 22 are provided with electrodes (the front electrode 40 and the back electrode 46) has been described. However, only one of them is provided, and active matrix driving is performed. Also good.

  In order to enable active matrix driving, the support substrate 38 and the support substrate 44 may include a TFT (thin film transistor) for each pixel. Since it is easy to laminate wiring and mount components, it is desirable to form the TFT on the back substrate 22 instead of the display substrate.

  If the display medium 12 is a simple matrix drive, the structure of the display device 10 having the display medium 12 described later can be simplified, and the active matrix drive using TFTs is simpler than the simple matrix drive. Display speed.

  Next, the gap member will be described. When the surface electrode 40 and the back electrode 46 are formed on the support substrate 38 and the support substrate 44, respectively, the electrodes between the electrodes that cause breakage of the surface electrode 40 and the back electrode 46 and adhesion of each particle of the particle group 34 are obtained. In order to prevent the occurrence of leakage, a surface layer 42 and a surface layer 48 as dielectric films are formed on the surface electrode 40 and the back electrode 46, respectively, as necessary.

  Examples of materials for forming the surface layer 42 and the surface layer 48 include polycarbonate, polyester, polystyrene, polyimide, epoxy, polyisocyanate, polyamide, polyvinyl alcohol, polybutadiene, polymethyl methacrylate, copolymerized nylon, ultraviolet curable acrylic resin, and fluorine resin. Etc. may be used.

  In addition to the insulating material described above, an insulating material containing a charge transport material may be used. Inclusion of a charge transport material improves particle chargeability by injecting particles into the particle, and when the charge amount of the particle becomes extremely large, the charge of the particle is leaked and the charge amount of the particle is stabilized. An effect is obtained.

Examples of the charge transport material include a hydrazone compound, a stilbene compound, a pyrazoline compound, and an arylamine compound that are hole transport materials. Further, a fluorenone compound, a diphenoquinone derivative, a pyran compound, zinc oxide, or the like, which is an electron transport material, may be used. Further, a self-supporting resin having a charge transporting property may be used.
Specific examples thereof include polyvinyl carbazole and polycarbonate obtained by polymerization of a specific dihydroxyarylamine and bischloroformate described in US Pat. No. 4,806,443. Since the dielectric film may affect the charging characteristics and fluidity of the particles, it is appropriately selected according to the composition of the particles. Since the display substrate which is one of the substrates needs to transmit light, it is preferable to use a transparent one of the above materials.

  Next, the gap member will be described. The gap member 24 for maintaining a gap between the display substrate 20 and the back substrate 22 is formed so as not to impair the light-transmitting property of the display substrate 20, and is a thermoplastic resin, a thermosetting resin, or an electron beam curing. It is made of resin, photo-curing resin, rubber, metal or the like.

The gap member 24 may be integrated with either the display substrate 20 or the back substrate 22. In this case, the support substrate 38 or the support substrate 44 is manufactured by performing etching processing, laser processing processing, press processing processing, printing processing, or the like using a previously manufactured mold.
In this case, the gap member 24 is fabricated on either the display substrate 20 side, the back substrate 22 side, or both.

  The gap member 24 may be colored or colorless, but is preferably colorless and transparent so as not to adversely affect the display image displayed on the display medium 12, and in this case, for example, transparent such as polystyrene, polyester, or acrylic Resin or the like is used.

  The particulate gap member 24 is also preferably transparent, and glass particles are used in addition to transparent resin particles such as polystyrene, polyester, or acrylic.

  Note that “transparent” means having a transmittance of 60% or more with respect to visible light.

  Next, the large diameter colored particle group will be described. The large-diameter colored particle group 36 is an uncharged particle group, is composed of large-diameter colored particles having optical reflection characteristics different from that of the particle group 34, and is a reflective member that displays a color different from that of the particle group 34. It functions. And it also has a function as a gap member to move without hindering movement between the display substrate 20 and the back substrate 22. That is, each particle of the particle group 34 is moved from the back substrate 22 side to the display substrate 20 side or from the display substrate 20 side to the back substrate 22 side through the gap of the large-diameter colored particle group 36. As the color of the large-diameter colored particle group 36, for example, white or black is preferably selected so as to be a background color. In the present embodiment, the case where the large-diameter colored particle group 36 is white will be described, but the present invention is not limited to this color.

  The large-diameter colored particle group 36 uses, for example, particles in which a white pigment such as titanium oxide, silicon oxide, or zinc oxide is dispersed in polystyrene, polyethylene, polypropylene, polycarbonate, PMMA, acrylic resin, phenol resin, formaldehyde condensate, or the like. Is done. Moreover, when applying particles other than white as the particles constituting the colored member, for example, the above-described resin particles containing a pigment or dye of a desired color may be used. If the pigment or dye is, for example, RGB or YMC color, a general pigment or dye used for printing ink or color toner may be used.

  In order to enclose the large-diameter colored particle group 36 between the substrates, for example, an inkjet method or the like is performed. Further, when the large-diameter colored particle group 36 is fixed, for example, after enclosing the large-diameter colored particle group 36, the large-diameter colored particle group 36 is heated (and pressurized if necessary), and the particle group surface layer of the large-diameter colored particle group 36. This is performed while maintaining the particle gap.

  The size of the cell in the display medium 12 is closely related to the resolution of the display medium 12, and the display medium 12 capable of displaying a high-resolution image as the cell is smaller can be manufactured. The length of the twelve display substrates 20 in the plate surface direction is about 10 μm to 1 mm.

  In order to fix the display substrate 20 and the back substrate 22 to each other through the gap member 24, fixing means such as a combination of bolts and nuts, a clamp, a clip, and a substrate fixing frame are used. Also, fixing means such as an adhesive, heat melting, and ultrasonic bonding may be used.

  The display medium 12 configured as described above includes, for example, a bulletin board capable of storing and rewriting images, a circulation version, an electronic blackboard, an advertisement, a signboard, a flashing sign, electronic paper, an electronic newspaper, an electronic book, and a copier / printer. Used for document sheets etc.

  As described above, the display device 10 according to the present embodiment includes the display medium 12, the voltage application unit 16 that applies a voltage to the display medium 12, and the control unit 18 (FIG. 1). reference).

  The voltage application unit 16 is electrically connected to the front electrode 40 and the back electrode 46. In the present embodiment, the case where both the front electrode 40 and the back electrode 46 are electrically connected to the voltage application unit 16 will be described. However, one of the front electrode 40 and the back electrode 46 is grounded. The other may be connected to the voltage application unit 16.

  The voltage application unit 16 is connected to the control unit 18 so as to be able to exchange signals.

  The control unit 18 stores in advance various programs such as a CPU (Central Processing Unit) that controls the operation of the entire apparatus, a RAM (Random Access Memory) that temporarily stores various data, and a control program that controls the entire apparatus. It can also be configured as a microcomputer including a read only memory (ROM).

  The voltage application unit 16 is a voltage application device for applying a voltage to the front electrode 40 and the back electrode 46, and applies a voltage according to the control of the control unit 18 between the front electrode 40 and the back electrode 46.

  Next, the operation of the display device 10 will be described. This operation will be described according to the operation of the control unit 18.

  Here, the case where the particle group 34 enclosed in the display medium 12 is black and is negatively charged will be described. In the following description, it is assumed that the dispersion medium 50 is transparent and the large-diameter colored particle group 36 is white. That is, in this embodiment, the case where the display medium 12 displays black or white by the movement of the particle group 34 will be described.

First, an initial operation signal indicating that the voltage is applied for a predetermined time so that the surface electrode 40 is a negative electrode and the back electrode 46 is a positive electrode is output to the voltage application unit 16. When a negative electrode and a voltage equal to or higher than a threshold voltage at which the concentration variation ends is applied between the substrates, the particles constituting the particle group 34 charged in the negative electrode move to the back substrate 22 side, and are applied to the back substrate 22. (See FIG. 2A).
At this time, the color of the display medium 12 visually recognized from the display substrate 20 side is visually recognized as white as the color of the large-diameter colored particle group 36.

  The T1 time may be stored in advance in a memory such as a ROM (not shown) in the control unit 18 as information indicating the voltage application time in the voltage application in the initial operation. Then, information indicating the predetermined time may be read when the process is executed.

  Next, the polarity of the voltage applied between the substrates is reversed between the surface electrode 40 and the back electrode 46, and when the voltage is applied with the surface electrode 40 as the positive electrode and the back electrode 46 as the negative electrode, FIG. As shown in B), the particle group 34 moves to the display substrate 20 side and reaches the display substrate 20 side, and black display by the particle group 34 is performed.

-Second Embodiment-
The display device according to the second embodiment will be described below. FIG. 3 is a schematic configuration diagram of a display device according to the second embodiment. FIG. 4 is a diagram schematically showing a relationship between an applied voltage and a moving amount (display density) of particles in the display device according to the second embodiment. FIG. 5 is an explanatory diagram schematically showing the relationship between the voltage mode applied between the substrates of the display medium and the particle movement mode in the display device according to the second embodiment.

  The display device 10 according to the second embodiment is a form in which two or more types of particle groups are applied. Two or more kinds of particle groups are all charged with the same polarity.

As shown in FIG. 3, the display device 10 according to the present embodiment includes a display medium 12, a voltage application unit 16 that applies a voltage to the display medium 12, and a control unit 18.
Note that the display device 10 according to the present embodiment has substantially the same configuration as the display device 10 described in the first embodiment, and thus the same reference numerals are given to the same configuration and detailed description thereof is omitted.

The display medium 12 includes a display substrate 20 that serves as an image display surface, a rear substrate 22 that faces the display substrate 20 with a gap, and holds the substrates at a predetermined interval, and between the display substrate 20 and the rear substrate 22. The gap member 24 is configured to include a plurality of cells, a particle group 34 enclosed in each cell, and a large-diameter colored particle group 36 having optical reflection characteristics different from those of the particle group 34.
The opposing surfaces of the display substrate 20 and the back substrate 22 are charged in the same manner as in the first embodiment, and the processing layer 21 and the processing layer 23 are provided on the opposing surfaces.

  In the present embodiment, as the particle group 34, a plurality of types of particle groups 34 having different colors are dispersed in the dispersion medium 50.

In this embodiment, as the three kinds of particle groups 34, the yellow color yellow particle group 34Y, the magenta magenta particle group 34M, and the cyan color cyan particle group 34C are dispersed as the particle groups 34 having different colors. However, it is not limited to three types.
The plurality of types of particle groups 34 are particle groups that perform electrophoresis between substrates, and the absolute value of the voltage required to move in accordance with the electric field is different for each color particle group. That is, each color particle group 34 (yellow particle group 34Y, magenta particle group 34M, and cyan particle group 34C) has a voltage range necessary for moving the color particle group 34 for each color. Are different.

  As each particle of a plurality of types of particle groups 34 having different absolute values of voltages necessary to move according to the electric field, for example, among the materials constituting the particle group 34 described in the first embodiment, for example, It can be obtained by preparing particle dispersions containing particles having different charge amounts by mixing the charge control material, the amount of magnetic powder, the type and concentration of the resin constituting the particles, and the like.

  Here, as described above, the yellow particle group 34Y, the magenta particle group 34M, and the cyan particle group 34C having different colors are dispersed as the three types of particle groups 34 in the display medium 12 according to the present embodiment. These plural kinds of particle groups 34 have different absolute values of voltages necessary for moving in accordance with the electric field in the respective color particle groups.

  In the present embodiment, the absolute value of the voltage when each of the three color particle groups, that is, the magenta magenta particle group 34M, the cyan cyan particle group 34C, and the yellow yellow particle group 34Y starts to move is used. In the following description, it is assumed that the magenta magenta particle group 34M is | Vtm |, the cyan cyan particle group 34C is | Vtc |, and the yellow yellow particle group 34Y is | Vty |. Also, the absolute value of the maximum voltage for moving almost all of the three color particle groups of the magenta particle group 34M, the cyan cyan particle group 34C, and the yellow yellow particle group 34Y of each color particle group 34. Assuming that the magenta magenta particle group 34M is | Vdm |, the cyan cyan particle group 34C is | Vdc |, and the yellow yellow particle group 34Y is | Vdy |.

  The absolute values of Vtc, −Vtc, Vdc, −Vdc, Vtm, −Vtm, Vdm, −Vdm, Vty, −Vty, Vdy, and −Vdy described below are | Vtc | <| Vdc | <| Description will be made assuming that the relationship is Vtm | <| Vdm | <| Vty | <| Vdy |.

  Specifically, as shown in FIG. 4, for example, the three types of particle groups 34 are all dispersed in the dispersion medium 50 in a state of being charged with the same polarity, and are necessary for moving the cyan particle groups 34C. Absolute value of voltage range | Vtc ≦ Vc ≦ Vdc | (absolute value of a value between Vtc and Vdc), absolute value of voltage range necessary for moving magenta particle group 34M | Vtm ≦ Vm ≦ Vdm | (Vtm The absolute value of the value between Vty and Vdm), and the absolute value of the voltage range necessary to move the yellow particle group 34Y | Vty ≦ Vy ≦ Vdy | (the absolute value of the value between Vty and Vdy) It is set to be large without overlapping in order.

  Further, in order to independently drive the particle groups 34 of the respective colors, the absolute value | Vdc | of the maximum voltage for moving almost all the cyan particle groups 34C is the absolute value of the voltage range necessary for moving the magenta particle group 34M. Value | Vtm ≦ Vm ≦ Vdm | (the absolute value of the value between Vtm and Vdm) and the absolute value of the voltage range necessary to move the yellow particle group 34Y | Vty ≦ Vy ≦ Vdy | (Vty to Vdy The absolute value of the value between) is set smaller. In addition, the absolute value | Vdm | of the maximum voltage for moving almost all of the magenta particle group 34M is the absolute value of the voltage range required for moving the yellow particle group 34Y | Vty ≦ Vy ≦ Vdy | (from Vty to Vdy). Is set to be smaller than the absolute value).

  That is, in this embodiment, the voltage groups necessary for moving the color particle groups 34 are set so as not to overlap, so that the particle groups 34 for each color are independently driven.

The “voltage range necessary for moving the particle group 34” means the voltage necessary for the particle to start moving and the change in display density even if the voltage and voltage application time are further increased from the start of movement. It shows the voltage range until it disappears and the display density is saturated.
The “maximum voltage required to move almost all the particle groups 34” means that even if the voltage and the voltage application time are further increased from the start of the movement, the display density does not change and the display density is saturated. Indicates voltage.
Further, “almost all” means that there is a variation in the characteristics of the particle groups 34 of the respective colors, so that some of the characteristics of the particle groups 34 are different to the extent that they do not contribute to the display characteristics. That is, even if the voltage and the voltage application time are further increased from the start of the movement described above, the display density does not change and the display density is saturated.
“Display density” is the color density on the display surface side measured with the optical density (Optical Density = 0D) reflection densitometer X-rite's reflection densitometer. Apply a voltage and gradually change this voltage in the direction of increasing the measured concentration (increase or decrease the applied voltage) to saturate the concentration change per unit voltage, and in that state, adjust the voltage and voltage application time. Even when the density is increased, the density does not change, and the density is shown when the density is saturated.

  In the display medium 12 according to the present embodiment, the voltage applied between the substrates is gradually increased by applying a voltage from 0 V between the display substrate 20 and the back substrate 22 to increase the voltage value of the applied voltage. When the value exceeds + Vtc, the display density starts to change due to the movement of the cyan particle group 34C in the display medium 12. Further, when the voltage value is increased and the voltage applied between the substrates becomes + Vdc, the change in display density due to the movement of the cyan particle group 34C in the display medium 12 stops.

  When the voltage value is further increased and the voltage applied between the display substrate 20 and the back substrate 22 exceeds + Vtm, a change in display density due to the movement of the magenta particle group 34M starts to appear in the display medium 12. When the voltage value is further increased and the voltage applied between the display substrate 20 and the back substrate 22 becomes + Vdm, the change in display density due to the movement of the magenta particle group 34M in the display medium 12 stops.

  Further, when the voltage value is increased and the voltage applied between the substrates exceeds + Vty, a change in display density due to the movement of the yellow particle group 34Y starts to appear in the display medium 12. When the voltage value is further increased and the voltage applied between the substrates becomes + Vdy, the change in display density due to the movement of the yellow particle group 34Y in the display medium 12 stops.

  On the other hand, if the negative voltage from 0V is applied between the display substrate 20 and the back substrate 22 to gradually increase the absolute value of the voltage and the absolute value of the voltage −Vtc applied between the substrates is exceeded. In the display medium 12, the display density starts to change due to the movement of the cyan particle group 34C between the substrates. Furthermore, when the absolute value of the voltage value is increased and the voltage applied between the display substrate 20 and the rear substrate 22 becomes −Vdc or more, the change in display density due to the movement of the cyan particle group 34C in the display medium 12 occurs. Stop.

  When the negative voltage is further applied by increasing the absolute value of the voltage value, and the voltage applied between the display substrate 20 and the rear substrate 22 exceeds the absolute value of −Vtm, the magenta particles are displayed on the display medium 12. A change in display density due to movement of the group 34M begins to appear. When the absolute value of the voltage value is further increased and the voltage applied between the display substrate 20 and the back substrate 22 becomes −Vdm, the change in display density due to the movement of the magenta particle group 34M in the display medium 12 stops. .

  When the absolute value of the voltage value is further increased to apply a negative voltage, and the voltage applied between the display substrate 20 and the back substrate 22 exceeds the absolute value of −Vty, yellow particles are displayed on the display medium 12. The display density starts to change due to the movement of the group 34Y. When the absolute value of the voltage value is further increased and the voltage applied between the substrates becomes −Vdy, the change in display density due to the movement of the yellow particle group 34Y in the display medium 12 stops.

  That is, in the present embodiment, as shown in FIG. 4, the voltage applied between the substrates is within the range of −Vtc to Vtc (voltage range | Vtc | or less) between the display substrate 20 and the back substrate 22. When applied between the substrates, the particle groups 34 (cyan particle group 34C, magenta particle group 34M, and yellow particle group 34Y) move so much that the display density of the display medium 12 changes. I can say no. When a voltage greater than the absolute value of the voltage + Vtc and the voltage −Vtc is applied between the substrates, the degree of change in the display density of the display medium 12 for the cyan particle group 34C among the three color particle groups 34 occurs. The display density starts to change for the first time, and when a voltage equal to or higher than the absolute value | Vdc | of the voltage −Vdc and the voltage Vdc is applied, the display density per unit voltage does not change.

  Furthermore, when a voltage that is applied between the substrates is between −Vtm and Vtm (voltage range | Vtm | or less) is applied between the display substrate 20 and the back substrate 22, the display medium Thus, it can be said that there is no movement of the particles of the magenta particle group 34M and the yellow particle group 34Y to the extent that the display density of 12 changes. When a voltage higher than the absolute value of the voltage + Vtm and the voltage −Vtm is applied between the substrates, the display density of the display medium 12 is changed for the magenta particle group 34M and the magenta particle group 34M of the yellow particle group 34Y. The display density per unit voltage starts to change to the extent that particles are generated, and when the voltage −Vdm and voltage Vdm absolute value | Vdm | or more are applied, the display density changes. Disappear.

  Further, when a voltage that is applied between the substrates is between -Vty and Vty (voltage range | Vty | or less) is applied between the display substrate 20 and the back substrate 22, the display medium 12 It can be said that there is no movement of the particles of the yellow particle group 34Y to the extent that the display density changes. When a voltage greater than the absolute value of the voltage + Vty and the voltage −Vty is applied between the substrates, the yellow particle group 34Y starts to move and display a particle that causes a change in the display density of the display medium 12. When the density starts to change and a voltage equal to or higher than the absolute value | Vdy | of the voltage −Vdy and the voltage Vdy is applied, the display density does not change.

  Next, with reference to FIG. 5, the mechanism of particle movement when an image is displayed on the display medium 12 will be described.

  For example, the display medium 12 will be described assuming that the yellow particle group 34Y, the magenta particle group 34M, and the cyan particle group 34C described with reference to FIG.

  In the following, the voltage applied between the substrates that is larger than the absolute value of the voltage necessary for the particles constituting the yellow particle group 34Y to start moving and less than or equal to the maximum voltage of the yellow particle group 34Y is referred to as “large voltage”. The voltage applied between the substrates that is larger than the absolute value of the voltage necessary for the particles constituting the magenta particle group 34M to start moving and is equal to or less than the maximum voltage of the magenta particle group 34M is referred to as “medium voltage”. The voltage applied between the substrates that is larger than the absolute value of the voltage required for the particles constituting the cyan particle group 34C to start moving and below the maximum voltage of the cyan particle group 34C is referred to as a “small voltage”. To do.

  Further, when a higher voltage is applied between the substrates on the display substrate 20 side than the back substrate 22 side, the respective voltages are referred to as “+ large voltage”, “+ medium voltage”, and “+ small voltage”, respectively. . Further, when a higher voltage is applied to the back substrate 22 side than the display substrate 20 side, the respective voltages are referred to as “−large voltage”, “−medium voltage”, and “−small voltage”, respectively. I will explain.

  As shown in FIG. 5A, when all of the magenta particle group 34M, the cyan particle group 34C, and the yellow particle group 34Y as all the particle groups are positioned on the back substrate 22 side in the initial state (white display). State), when a “+ high voltage” is applied between the display substrate 20 and the back substrate 22 from this initial state, all the particle groups include a magenta particle group 34M, a cyan particle group 34C, and a yellow particle group 34Y. Moves to the display substrate 20 side. In this state, even if the voltage application is canceled, each particle group does not move while adhering to the display substrate 20 side, and subtractive color mixing (magenta) by the magenta particle group 34M, the cyan particle group 34C, and the yellow particle group 34Y. In this case, the black color is displayed by the subtractive color mixture of cyan and yellow. (See FIG. 5B).

  Next, when “−medium voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5B, the magenta particle group 34 </ b> M among the particle groups 34 of all colors and cyan The particle group 34 </ b> C moves to the back substrate 22 side. For this reason, since only the yellow particle group 34Y is attached to the display substrate 20 side, yellow display is performed (see FIG. 5C).

  Further, when “+ small voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5C, the magenta particle group 34M and the cyan particle group 34C moved to the back substrate 22 side. The cyan particle group 34C moves to the display substrate 20 side. For this reason, the yellow particle group 34Y and the cyan particle group 34C are attached to the display substrate 20 side, and green is displayed by subtractive color mixture of yellow and cyan (see FIG. 5D).

  5B, when a “−small voltage” is applied between the display substrate 20 and the back substrate 22, the cyan particle groups 34C of all the particle groups 34 move to the back substrate 22 side. To do. For this reason, since the yellow particle group 34Y and the magenta particle group 34M are attached to the display substrate 20 side, red display is performed by additive mixing of cyan and magenta (see FIG. 5I).

  On the other hand, when “+ medium voltage” is applied between the display substrate 20 and the back substrate 22 from the initial state shown in FIG. 5A, all the particle groups 34 (magenta particle group 34M, cyan particle group 34C) are applied. , And the yellow particle group 34Y), the magenta particle group 34M and the cyan particle group 34C move to the display substrate 20 side. For this reason, since the magenta particle group 34M and the cyan particle group 34C are attached to the display substrate 20 side, blue is displayed by the subtractive color mixing of magenta and cyan (see FIG. 5E).

When a “−small voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5E, the magenta particle group 34M and the cyan particle group 34C adhering to the display substrate 20 side. Among them, the cyan particle group 34C moves to the back substrate 22 side.
Therefore, only the magenta particle group 34M is attached to the display substrate 20 side, so that a magenta color is displayed (see FIG. 5F).

When a “−high voltage” is applied between the display substrate 20 and the back substrate 22 from the state of FIG. 5F, the magenta particle group 34M adhering to the display substrate 20 side is moved to the back substrate 22 side. Moving.
For this reason, since nothing is adhered to the display substrate 20 side, white as the color of the large-diameter colored particle group 36 is displayed (see FIG. 5G).

  When a “+ small voltage” is applied between the display substrate 20 and the back substrate 22 from the initial state shown in FIG. 5A, all the particle groups 34 (magenta particle group 34M, cyan particle group) are applied. 34C and the yellow particle group 34Y), the cyan particle group 34C moves to the display substrate 20 side. For this reason, the cyan particle group 34C adheres to the display substrate 20 side, so that a cyan color is displayed (see FIG. 5H).

Further, when a “−large voltage” is applied between the display substrate 20 and the back substrate 22 from the state shown in FIG. 5I, all the particle groups 34 are back as shown in FIG. Moving to the substrate 22 side, white display is performed.
Similarly, when a “−high voltage” is applied between the display substrate 20 and the back substrate 22 from the state shown in FIG. 5D, all the particle groups 34 are formed as shown in FIG. Moving to the back substrate 22 side, white display is performed.

  In the present embodiment, by applying a voltage corresponding to each particle group 34 between the substrates, the desired particles are selectively moved according to the electric field generated by the voltage, so that particles of colors other than the desired color are dispersed. It is possible to suppress movement in the medium 50, to suppress color mixing in which colors other than a desired color are mixed, and to perform color display while suppressing deterioration in image quality of the display medium 12. In addition, if the absolute value of the voltage required for each particle group 34 to move according to the electric field is different from each other, even if the voltage ranges necessary for moving according to the electric field overlap with each other, clear color display is possible. However, when the voltage ranges are different from each other, color mixing is further suppressed and color display is realized.

  Further, by dispersing the cyan, magenta, and yellow color particle groups 34 in the dispersion medium 50, cyan, magenta, yellow, blue, red, green, and black are displayed, and, for example, a white large diameter is displayed. A white color is displayed by the colored particle group 36 and a specific color display is realized.

  As described above, in the display device 10 according to the present embodiment, similarly to the display device 10 described in the first embodiment, the particle group 34 reaches the display substrate 20 or the back substrate 22 and adheres to the display. Is done.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention.

[Example A]
(Example A1)
-Preparation of charge control material-(Adduct of epoxy-containing reactive polymer and amino-containing silicone)
A polymer containing an epoxy group was synthesized as a reactive polymer. Glycidyl methacrylate: 2 parts by mass, methyl methacrylate: 8 parts by mass, tetrahydrofuran (THF): 40 parts by mass, azobisvaleronitrile: 0.1 part by mass as a polymerization initiator are mixed, and polymerization is performed at 60 ° C. under nitrogen. Then, precipitation purification was performed with methanol to prepare a reactive polymer having an epoxy group as a reactive group having a weight average molecular weight of 20,000.

Next, TSF-4701 (Momentive Performance Materials: amino group equivalent 2500 g / mol) was used as a reactive silicone compound having a primary amino group at the terminal.
1: 1 mixture of toluene: THF: Reactive polymer synthesized previously in 50 parts by mass: 1 part by mass, TSF-4701: 4 parts by mass are dissolved by heating at 70 ° C. for 24 hours, epoxy group and silicone The system compound was subjected to an addition reaction. The produced addition reaction product was purified by precipitation in methanol to obtain a compound having a structural unit represented by the following structural formula A1. It was confirmed from the infrared absorption spectrum that the product was a polymer having a silicone chain added and contained an amino group. In addition, the product was dissolved at least 100 g / L in dimethyl silicone oil (KF-96L-2cs viscosity 2 cs manufactured by Shin-Etsu Silicone Co., Ltd.), and was found to be soluble in the dimethyl silicone oil. This product (addition reactant) was used as a charge control material.

-Preparation of display particle dispersion-
A negatively charged electrophoretic particle dispersion (display particle dispersion, the same applies hereinafter) was prepared by the following method.
Silaplane FM-0711 (manufactured by Chisso Corporation) which is a silicone monomer: 95 parts by mass and 5 parts by mass of glycidyl methacrylate are mixed with 100 parts by mass of silicone oil, and azobisvaleronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) is used as a polymerization initiator. : V-65) was added in an amount of 0.2 parts by mass, and polymerization was carried out at 55 ° C. for 10 hours to prepare a silicone-based dispersant A (reactive dispersant) containing an epoxy group. The weight average molecular weight was 300,000 as measured by GPC (gel permeation chromatography) method. And the 3 mass% silicone oil solution of the reactive silicone polymer A was prepared by diluting with silicone oil. In addition, as silicone oil, dimethyl silicone oil (KF-96L-2cs viscosity 2cs by Shin-Etsu Silicone Co., Ltd.) was used.

  Next, a commercially available product (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymer having a charging group was prepared as a 10% by mass aqueous solution of polymethacrylic acid (weight average molecular weight 50,000). Next, Ciba water-dispersed pigment solution (Unisperse magenta color: pigment concentration 16% by weight), 1 part by weight of the above polymethacrylic acid 10% by weight aqueous solution, and a stoichiometric amount of triethylamine to neutralize it. Are mixed with 10 parts by mass of a 3% by mass silicone oil solution of the above-mentioned silicone-based reactive dispersant A, and this is mixed with an ultrasonic crusher (UH-600S manufactured by SMT Corporation). The mixture was stirred for a minute to prepare a suspension in which an aqueous solution containing a polymer having a charged group and a pigment was dispersed and emulsified in silicone oil.

  Next, the suspension was decompressed (2 KPa) and heated (70 ° C.) for 1 hour to remove moisture, and magenta colored particles containing a polymer having a charged group and a pigment were dispersed in silicone oil. A silicone oil dispersion was obtained. Furthermore, this dispersion was heated at 100 ° C. for 3 hours to cause the reactive silicone dispersant A to react with and bind to the surface of the colored particles. After the reaction, the particles were settled using a centrifugal separator and purified by repeating washing with silicone oil. Further, the concentration was adjusted with silicone oil to prepare a 5% by mass display particle dispersion. It was 400 nm as a result of measuring the volume average particle diameter of the produced particle dispersion (Holiba LA-300: laser light scattering / diffraction particle size measuring device).

The following two types of dispersions were prepared using the electrophoretic particles prepared above. 1) a dispersion containing only the viscosity 2cs silicone oil (KF-96L-2cs manufactured by Shin-Etsu Silicone Co., Ltd.), and 2) a compound having the structural unit represented by the structural formula A1 prepared above in the dispersion (charge control material) ) Prepared at a concentration of 0.1% by mass.
The charge polarity of the electrophoretic particles in these dispersions is evaluated by enclosing the dispersion between two ITO electrode substrates (interelectrode gap is 100 μm) and alternately applying a DC voltage of 20 V to evaluate the migration direction. In 1), it was found that positive and negative electrophoretic particles were present in 1) and the polarities of the particles were not uniform, but in 2) all the particles were negatively charged and the polarities were uniform. As a result, the compound (charge control material) having the structural unit represented by the structural formula A1 showed good charge control properties. In addition, after the particles were electrically attached on the substrate, the voltage application was stopped and the sample was left for 1 hour, and the amount of change in optical density before and after being left was measured. I understood.

(Example A2)
-Preparation of charge control material-(Isocyanate-containing reactive polymer + Hydroxyl silicone-containing adduct)
A polymer containing an isocyanate group was synthesized as a reactive polymer. 2 parts by weight of Karenz MOI (made by Showa Denko) which is a methacrylate monomer having an isocyanate group, 7.5 parts by weight of methyl methacrylate, 0.5 parts by weight of dimethylaminoethyl methacrylate, 40 parts by weight of tetrahydrofuran (THF), azo as a polymerization initiator A reactive polymer containing an isocyanate group as a reactive group having a weight average molecular weight of 20,000 is obtained by mixing 0.1 parts by mass of bisvaleronitrile, polymerizing at 60 ° C. under nitrogen, purifying by precipitation with hexane. Produced.
XX-22-170BX (manufactured by Shin-Etsu Chemical Co., Ltd .: hydroxyl value 20 mgKOH / g) was used as a reactive silicone compound having a hydroxyl group at the terminal. In 50 parts by mass of THF (tetrahydrofuran), XX-22-170BX: 4 parts by mass, 1 part by mass of the reactive polymer having an isocyanate group synthesized earlier were dissolved and reacted at 60 ° C. for 24 hours.
The produced addition reactant was purified by precipitation in methanol to obtain a compound having a structural unit represented by the following structural formula A2. It was confirmed from the infrared absorption spectrum that the product contained a polymer having a silicone chain added and an amino group. In addition, the product was dissolved at least 100 g / L in dimethyl silicone oil (KF-96L-2cs viscosity 2 cs manufactured by Shin-Etsu Silicone Co., Ltd.), and was found to be soluble in the dimethyl silicone oil. This product was used as a charge control material.

Next, the charge controllability was evaluated in the same manner using the same electrophoretic particle dispersion as prepared in Example A1.
1) Dispersion of only the viscosity 2cs silicone oil (KF-96L-2cs manufactured by Shin-Etsu Silicone Co., Ltd.), and 2) Compound having the structural unit represented by the structural formula A2 prepared above in the dispersion (charge control) Material) prepared at a concentration of 0.1% by mass.
The charge polarity of the electrophoretic particles in these dispersions is evaluated by enclosing the dispersion between two ITO electrode substrates (interelectrode gap is 100 μm) and alternately applying a DC voltage of 20 V to evaluate the migration direction. In 1), it was found that positive and negative electrophoretic particles were present in 1) and the polarities of the particles were not uniform, but in 2) all the particles were negatively charged and the polarities were uniform. As a result, the compound having the structural unit represented by the structural formula A2 (charge control material) showed good charge control properties. In addition, after the particles were electrically attached on the substrate, the voltage application was stopped and the sample was left for 1 hour, and the amount of change in optical density before and after being left was measured. I understood.

(Example A3)
-Preparation of charge control material-(Isocyanate-containing reactive polymer + hydroxyl-containing silicone adduct 2)
As the reactive polymer, the same polymer containing an isocyanate group as in Example 2 was used.
The same TSF-4701 (Momentive Performance Materials: amino group equivalent 2500 g / mol) as in Example A1 was used as the reactive silicone compound having a primary amino group at the terminal. Reactive polymer: 1 part by mass and TSF-4701: 3.5 parts by mass were dissolved in 50 parts by mass of THF, and the mixture was reacted by heating at 70 ° C. for 24 hours to cause an addition reaction between an epoxy group and a silicone compound. The resulting addition reaction product was purified by precipitation in methanol. It was confirmed from the infrared absorption spectrum that the product was a polymer having a silicone chain added and contained an amino group. In addition, the product was dissolved at least 100 g / L in dimethyl silicone oil (KF-96L-2cs viscosity 2 cs manufactured by Shin-Etsu Silicone Co., Ltd.), and was found to be soluble in the dimethyl silicone oil. This product was used as a charge control material.
Next, XX-22-170BX (manufactured by Shin-Etsu Chemical Co., Ltd .: hydroxyl value 20 mgKOH / g) was used as a reactive silicone compound having a hydroxyl group at the terminal. XX-22-170BX: 4 parts by mass and 1 part by mass of the previously synthesized reactive polymer were dissolved in 50 parts by mass of THF (tetrahydrofuran) and reacted at 60 ° C. for 24 hours.
The produced addition reactant was purified by precipitation in methanol to obtain a compound having a structural unit represented by the following structural formula A3. It was confirmed from the infrared absorption spectrum that the product contained a polymer having a silicone chain added and an amino group. The polymer was soluble in dimethyl silicone oil (KF-96-2CS manufactured by Shin-Etsu Silicone).

The charge controllability was evaluated in the same manner using the same electrophoretic particle dispersion as that prepared in Example A1.
1) Dispersion of only the viscosity 2cs silicone oil (KF-96L-2cs manufactured by Shin-Etsu Silicone Co.), and 2) a compound having the structural unit represented by the structural formula A3 prepared above in the dispersion (charge control) Material) prepared at a concentration of 0.1% by mass.
The charged polarity of the electrophoretic particles in these dispersions was determined by sealing the dispersion between two ITO electrode substrates (interelectrode gap was 100 μm), and applying a DC voltage to evaluate the migration direction. As a result, it was found that positive, negative, and bipolar electrophoretic particles existed in 1), and the polarities of the particles were not uniform. In 2), all particles were negatively charged, and it was clear that the polarities were uniform. Thus, the compound (charge control material) having the structural unit represented by the structural formula A3 showed good charge controllability. In addition, after the particles were electrically attached on the substrate, the voltage application was stopped and the sample was left for 1 hour, and the amount of change in optical density before and after being left was measured. I understood.

(Example A4)
-Preparation of charge control material-(Isocyanate-containing reactive polymer + hydroxyl-containing silicone adduct 3)
A polymer containing an isocyanate group was synthesized as a reactive polymer. Karenz MOI (manufactured by Showa Denko) which is a methacrylate monomer having an isocyanate group, 2.5 parts by mass, 7.5 parts by mass of methyl methacrylate, 40 parts by mass of tetrahydrofuran (THF), 0.1 mass of azobisvaleronitrile as a polymerization initiator Parts were mixed, polymerized at 60 ° C. under nitrogen, and purified by precipitation with hexane to prepare a reactive polymer containing an isocyanate group as a reactive group having a weight average molecular weight of 20,000.
XX-22-170BX (manufactured by Shin-Etsu Chemical Co., Ltd .: hydroxyl value 20 mgKOH / g) as in Example 2 was used as a reactive silicone compound having a hydroxyl group at the terminal. XX-22-170BX: 3 parts by mass in THF (tetrahydrofuran) 50 parts by mass, 1 part by mass of the previously synthesized reactive polymer having an isocyanate group was dissolved, reacted at 60 ° C. for 24 hours, and then adipic acid 1.5 parts by mass was added, and the mixture was heated at 60 ° C. for 24 hours to react the residual isocyanate group with one of the excess carboxyl groups of adipic acid, thereby introducing a carboxyl group.
The produced addition reactant was purified by precipitation in methanol to obtain a compound having a structural unit represented by the following structural formula A4. From the infrared absorption spectrum, the product was confirmed to contain a polymer having a silicone chain added and a carboxyl group. In addition, the product was dissolved at least 100 g / L in dimethyl silicone oil (KF-96L-2cs viscosity 2 cs manufactured by Shin-Etsu Silicone Co., Ltd.), and was found to be soluble in the dimethyl silicone oil.

-Preparation of display particle dispersion-
A positively charged electrophoretic particle dispersion was prepared by the following method.
As a polymer having a charged group, a 9/1 copolymer (weight average molecular weight 60,000) of N-vinylpyrrolidone and N, N-diethylaminoethyl methacrylate was synthesized by ordinary radical solution polymerization. Further, this resin was added with an equimolar amount or more of ethyl iodide with respect to the amino group in isopropanol, and heated at 80 ° C. for 1 hour to quaternize the amino group and purified again as a solid.
Except for Ciba water-dispersed pigment solution (Unisperse cyan color: pigment concentration 26 wt%) as the pigment resin, the same procedure was used with the same silicone-based reactive dispersant A as in Example A1. A 5 wt% concentration particle dispersion containing the pigment was prepared.
The volume dispersion of the produced particle dispersion was 350 nm.

The charge controllability was similarly evaluated using this electrophoretic particle dispersion.
1) Dispersion of only the viscosity 2cs silicone oil (KF-96L-2cs manufactured by Shin-Etsu Silicone Co., Ltd.), and 2) a compound having the structural unit represented by the structural formula A4 prepared above in the dispersion (charge control) Material) prepared at a concentration of 0.1% by mass.
The charged polarity of the electrophoretic particles in these dispersions was determined by sealing the dispersion between two ITO electrode substrates (interelectrode gap was 100 μm), and applying a DC voltage to evaluate the migration direction. As a result, it was found in 1) that positive / negative and bipolar electrophoretic particles were present and the polarity of the particles was not uniform, but in 2) it was clear that all particles were positively charged and had the same polarity. Thus, the compound (charge control material) having the structural unit represented by the structural formula A4 showed good charge controllability. In addition, after the particles were electrically attached on the substrate, the voltage application was stopped and the sample was left for 1 hour, and the amount of change in optical density before and after being left was measured. I understood.

(Example A5)
-Optical element model preparation and evaluation-
Prepare an ITO glass substrate (5 cm x 10 cm, thickness 2 mm) one by one, form an offset shape with a part of the electrode surface for wiring, and form a tape spacer on the outer periphery (partial opening is formed) As a result, a plurality of cell structures (empty cells) were produced in which two substrates were bonded to each other with an interval of 100 μm with the electrode substrate surfaces facing each other.
A dispersion in which true spherical particles (made by Sekisui Plastics Co., Ltd.) having a volume average particle diameter of 6 μm made of polymethyl methacrylate containing titanium oxide at a concentration of 40% by mass are dispersed in ethanol at 10% by mass, This was infiltrated into the cell from the opening, and then ethanol was dried to fill with white particles.
Further, each of the electrophoretic particle dispersions containing the compounds (charge control materials) having the structural units represented by the structural formulas A1 to A4 described in Examples A1 to A4 was injected by the decompression method, and the openings were sealed. Four types of evaluation optical elements were produced.
When DC voltages having different polarities of 20 V were alternately applied to the manufactured optical element, each element could alternately express white and magenta or cyan. In addition, the repeating stability was 100,000 times or more, and neither aggregation of electrophoretic particles nor deterioration of dispersibility was observed.
Furthermore, by applying a DC voltage, each of the display density immediately after the voltage application is stopped (electric field is turned off) in a state where each display color of magenta or cyan is formed, and each after 24 hours from the stop of the voltage application. When the display density was measured with X-rite (manufactured by X-rite), no change was observed, and a stable memory property was shown.

(Comparative Example A-1)
A charge control polymer (charge control material) containing a known amino group was synthesized and subjected to comparative evaluation.
Silaplane FM-0711 (manufactured by Chisso Corporation) which is a silicone monomer: 19 parts by mass, 1 part by mass of dimethylaminoethyl methacrylate are mixed with 200 parts by mass of silicone oil (KF-96L-1cs made by Shin-Etsu Silicone), and polymerization is performed. 0.1 parts by mass of azobisvaleronitrile (manufactured by Wako Pure Chemicals: V-65) was added as an initiator, and polymerization was carried out at 60 ° C. for 6 hours. After completion of the polymerization, the solvent and unreacted monomer were removed by evaporation to obtain an amino-containing silicone polymer. Further, the product was dissolved in dimethyl silicone oil (KF-96L-2cs manufactured by Shin-Etsu Silicone Co., Ltd.) at least 100 g / L or more, and was found to be soluble in the dimethyl silicone oil.

In the electrophoretic particle dispersion prepared in Example A1, the amino-containing polymer (charge control material) prepared above was added at a concentration of 0.1%, 0.5%, and 2% by weight with respect to the dispersion. The added dispersion for evaluation was prepared.
The charged polarity of the electrophoretic particles in these dispersions was determined by sealing the dispersion between two ITO electrode substrates (interelectrode gap was 100 μm), and applying a DC voltage to evaluate the migration direction. As a result, it was found that at 0.1 mass% and 0.5 mass% concentrations, positive / negative and bipolar electrophoretic particles exist and the polarities of the particles are not uniform. On the other hand, it was found that almost all particles having a concentration of 1% by mass were negatively charged and the polarities were almost uniform. On the other hand, in the evaluation of the memory property similar to the example, the one with 1% concentration is that after leaving for 1 hour, almost all particles are peeled off from the substrate surface, and the change in optical density before and after leaving is large and the memory property is low. found. From these results, when the polymer of the known example is added, a large amount of addition is necessary to stabilize the polarity, and in the state where the polarity is stable, the memory property which is a feature of electrophoresis is low. This proved that the effectiveness of this example was confirmed.

[Example B]
(Example B1)
-Adjustment of charge control material-
(Alkylation of side chain amino group of silicone compound)
First, as a reactive silicone compound in which a primary amino group is substituted on a methyl group (—CH ₃ ) in a dimethyl silicone chain (—Si (CH ₃ ) ₂ O—), “KF-865: functional group equivalent 5000 g / Mol "(manufactured by Shin-Etsu Chemical Co., Ltd.) was prepared. 10 parts by mass of dimethyl silicone oil having a primary amino group in the side chain and 0.7 parts by mass of ethyl iodide are mixed with 50 parts by mass of isopropyl alcohol, and heated at 70 ° C. for 5 hours, so that two amino groups are added to the amino group. Purification was performed after adding an ethyl group, and a silicone compound having a diethylamino group in the side chain represented by the following structural formula B1 was produced.
It was confirmed from the infrared absorption spectrum that the product was a dimethyl silicone compound having a diethylamino group. Further, the product was dissolved at least 100 g / L in dimethyl silicone oil (KF-96L-2cs manufactured by Shin-Etsu Silicone Co., Ltd., viscosity 2 cs), and it was found that the product was soluble in the dimethyl silicone oil. This product (addition reactant) was used as a charge control material.
The obtained charge control material is a compound having the following structural formula B1. In the compound represented by the general formula (22-1), X represents a group represented by the structural formula (22-A), n represents 1 to 200, and m represents 1 to 1000. In the structural formula (22-A), R represents a propylene group, R ¹ represents an ethyl group, and R ² represents an ethyl group.

Next, using the same electrophoretic particle dispersion as in Example A1, the following two types of dispersions were prepared. 1) A dispersion of only the 2cs silicone oil (KF-96L-2cs manufactured by Shin-Etsu Silicone), and 2) a concentration of the compound having the structural formula B1 (charge control material) prepared above in the dispersion of 0. Prepared at 1% by weight.
The charge polarity of the electrophoretic particles in these dispersions is evaluated by enclosing the dispersion between two ITO electrode substrates (interelectrode gap is 100 μm) and alternately applying a DC voltage of 20 V to evaluate the migration direction. In 1), it was found that positive and negative electrophoretic particles were present in 1) and the polarities of the particles were not uniform, but in 2) all the particles were negatively charged and the polarities were uniform. The compound having the structural formula B1 (charge control material) showed good charge controllability. In addition, after the particles were electrically attached on the substrate, the voltage application was stopped and the sample was left for 1 hour, and the amount of change in optical density before and after being left was measured. I understood.

(Example B2)
-Adjustment of charge control material-
(Amination of the side chain epoxy group of silicone compound)
10 parts by mass of dimethyl silicone oil having an epoxy group in the side chain (KF-101: functional group equivalent: 350 g / mol: manufactured by Shin-Etsu Chemical Co., Ltd.) and 3 parts by mass of diethylamine are mixed with 50 parts by mass of isopropyl alcohol, and 5 at 70 ° C. The mixture was heated for an hour to allow the diethylamino group to undergo an addition reaction with the epoxy group and then purified to prepare a silicone compound having a diethylamino group in the side chain, represented by the following structural formula B2. It was confirmed from the infrared absorption spectrum that the product was a dimethyl silicone compound having a diethylamino group. Further, the product was dissolved at least 100 g / L in dimethyl silicone oil (KF-96L-2cs manufactured by Shin-Etsu Silicone Co., Ltd., viscosity 2 cs), and it was found that the product was soluble in the dimethyl silicone oil.

Using the same electrophoretic particle dispersion as in Example A1, the following two types of dispersions were prepared. 1) The above 1) a dispersion of only 2cs silicone oil (KF-96L-2cs made by Shin-Etsu Silicone), and 2) a diethylamino group in the side chain represented by the following structural formula B2 prepared above. A silicone compound (charge control material) prepared at a concentration of 0.1% by mass.
The charge polarity of the electrophoretic particles in these dispersions is evaluated by enclosing the dispersion between two ITO electrode substrates (interelectrode gap is 100 μm) and alternately applying a DC voltage of 20 V to evaluate the migration direction. In 1), it was found that positive and negative electrophoretic particles were present in 1) and the polarities of the particles were not uniform, but in 2) all the particles were negatively charged and the polarities were uniform. The silicone compound (charge control material) having a diethylamino group in the side chain represented by the following structural formula B2 showed good charge controllability. In addition, after the particles were electrically attached on the substrate, the voltage application was stopped and the sample was left for 1 hour, and the amount of change in optical density before and after being left was measured. I understood.

(Example B3)
-Adjustment of charge control material-
(Carboxylation of side chain epoxy group of silicone compound)
10 parts by mass of dimethyl silicone oil having an epoxy group in the side chain similar to Example B2 (KF-101: functional group equivalent 350 g / mol) and 8 parts by mass of adipic acid were mixed with 50 parts by mass of isopropyl alcohol at 70 ° C. The mixture was heated for 5 hours to cause addition reaction of one carboxyl group of adipic acid to an epoxy group and then purified to prepare a silicone compound having a carboxyl group in the side chain represented by the following structural formula B3. From the infrared absorption spectrum, the product was confirmed to be a dimethyl silicone compound having a carboxyl group. Further, the product was dissolved at least 100 g / L in dimethyl silicone oil (KF-96L-2cs manufactured by Shin-Etsu Silicone Co., Ltd., viscosity 2 cs), and it was found that the product was soluble in the dimethyl silicone oil.

A positively charged electrophoretic particle dispersion was prepared by the following method.
The following two types of dispersion liquids were prepared using the same electrophoretic particle dispersion liquid having a cationic group as in Example A4. 1) A dispersion containing only the 2cs silicone oil (KF-96L-2cs manufactured by Shin-Etsu Silicone), and 2) a silicone having a carboxyl group in the side chain represented by the structural formula B3 prepared above in the dispersion. A compound prepared at a concentration of 0.1% by mass.
The charge polarity of the electrophoretic particles in these dispersions is evaluated by enclosing the dispersion between two ITO electrode substrates (interelectrode gap is 100 μm) and alternately applying a DC voltage of 20 V to evaluate the migration direction. In 1), it was found that positive and negative electrophoretic particles existed in 1) and the polarities of the particles were not uniform, but in 2) all the particles were negatively charged and the polarities were uniform. As a result, the silicone compound (charge control material) having a carboxyl group in the side chain represented by the structural formula B3 showed good charge control properties. In addition, after the particles were electrically attached on the substrate, the voltage application was stopped and the sample was left for 1 hour, and the amount of change in optical density before and after being left was measured. I understood.

(Example B4)
-Optical element model preparation and evaluation 2-
As in Example A5, an ITO glass substrate (5 cm × 10 cm, thickness 2 mm) was prepared one by one, and an offset shape with a part of the electrode surface secured for wiring was formed, and a tape spacer was formed on the outer peripheral portion (one A plurality of cell structures (empty cells) in which two substrates are bonded to each other at an interval of 100 μm with the electrode substrate surfaces facing each other.
A dispersion in which true spherical particles (made by Sekisui Plastics Co., Ltd.) having a volume average particle diameter of 6 μm made of polymethyl methacrylate containing titanium oxide at a concentration of 40% by mass are dispersed in ethanol at 10% by mass, This was infiltrated into the cell from the opening, and then ethanol was dried to fill with white particles.
Further, each of the evaluation optical elements described in Examples B1 to B3 was injected with a dispersion of electrophoretic particles containing the compounds (charge control materials) represented by structural formulas B1 to B3 by the reduced pressure method, and the opening was sealed. Kinds were made.
When DC voltages having different polarities of 20 V were alternately applied to the manufactured optical element, each element could alternately express white and magenta or cyan. In addition, the repeating stability was 100,000 times or more, and neither aggregation of electrophoretic particles nor deterioration of dispersibility was observed.
Furthermore, by applying a DC voltage, each of the display density immediately after the voltage application is stopped (electric field is turned off) in a state where each display color of magenta or cyan is formed, and each after 24 hours from the stop of the voltage application. When the display density was measured with X-rite (manufactured by X-rite), no change was observed, and a stable memory property was shown.

(Comparative Example B-1)
A comparative silicone used in Examples B1 and B2 that was not subjected to addition reaction was added for comparative evaluation.
Silicone compound “KF-865: Functional group equivalent 5000 g / mol” having a primary amino group used in Examples B1 and B2 in the migrating particle dispersions prepared in Examples A1 and A4 (manufactured by Shin-Etsu Chemical Co., Ltd.) And dimethyl silicone oil “KF-101: functional group equivalent 350 g / mol” (manufactured by Shin-Etsu Chemical Co., Ltd.) having an epoxy group in the side chain was added at a concentration of 0.5% by mass.
The charged polarity of the electrophoretic particles in these dispersions was determined by sealing the dispersion between two ITO electrode substrates (interelectrode gap was 100 μm), and applying a DC voltage to evaluate the migration direction. As a result, it was found that in both dispersions, positive and negative electrophoretic particles were present and the polarities of the particles were not uniform. From these results, it was found that the polarity was stabilized by using the charge control material (addition reactant) of this example, and the effectiveness of this example was confirmed.

1 is a schematic configuration diagram of a display device according to a first embodiment. It is explanatory drawing which shows typically the movement aspect of a particle group when a voltage is applied between the board | substrates of the display medium of the display apparatus which concerns on 1st Embodiment. It is a schematic block diagram of the display apparatus which concerns on 2nd Embodiment. It is a diagram which shows typically the relation between the applied voltage and the amount of movement of particles (display density) in the display device concerning a 2nd embodiment. It is explanatory drawing which shows typically the relationship between the voltage aspect applied between the board | substrates of a display medium, and the movement aspect of particle | grains.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Display apparatus 12 Display medium 16 Voltage application part 18 Control part 20 Display substrate 22 Back substrate 24 Gap member 34 Particle group 34Y Yellow particle group 34C Cyan particle group 34M Magenta particle group 36 Large diameter colored particle group 38 Support substrate 40 Surface electrode 42 Surface layer 44 Support substrate 46 Back electrode 48 Surface layer 50 Dispersion medium

Claims (11)

  A first reactive adduct of a reactive polymer having a reactive functional group and a reactive silicone compound having a reactive functional group that undergoes an addition reaction with respect to the reactive functional group of the reactive polymer, and reactivity From a second reactive adduct of a reactive silicone compound having a functional group and at least one of an amine compound, a halogenated alkyl compound and a polybasic acid that undergo an addition reaction with respect to the reactive functional group of the reactive silicone compound. A charge control material that is at least one selected. The first reactive adduct is a reactive polymer having at least a monomer unit represented by the following general formula (1) and a reactive silicone system represented by the general formula (1-A) and the general formula (1-B). The charge control material according to claim 1, wherein the charge control material is an addition reaction product with at least one compound.

The charge control material according to claim 1, wherein the first reaction adduct is a polymer compound containing at least a structural unit represented by the following general formula (11).

(In the general formula (11), R ¹ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a halogen group. R ² represents the following structural formula (11-A) or structural formula (11- B represents a group represented by B), R ³ represents a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, R ⁴ represents an alkyl group having 1 to 10 carbon atoms, and X represents —COOCH ₂ CH. Represents a group represented by (OH)-, and p represents 0 or 1.)

(In the structural formula (11-A) or the structural formula (11-B), R ⁵ represents an alkylene group having 3 to 10 carbon atoms. R ⁶ is an alkyl group having 1 to 10 carbon atoms, or Represents an aminoalkyl group having 1 to 10 carbon atoms, and n1 represents an integer of 1 to 1000.)   The charge control material according to claim 1, wherein the first reaction adduct is a polymer compound composed of only the structural unit represented by the general formula (11). The charge control material according to claim 1, wherein the reactive silicone compound having a reactive functional group in the second reaction adduct is a reactive silicone compound represented by the following general formula (2).

The charge control material according to claim 1, wherein the second reaction adduct is a polymer compound containing a structural unit represented by the following general formula (22).

(In the general formula (22), X represents a group represented by the following structural formula (22-A) or structural formula (22-B).)

(In the structural formula (22-A) or the structural formula (22-B), R and R ³ each independently represents an alkylene group having 1 to 10 carbon atoms. R ¹ , R ² , R ⁴ , and R ⁵ represents each independently an alkyl group having 1 to 18 carbon atoms or an aromatic group.) The charge control material according to claim 1, wherein the second reaction adduct is a compound represented by the following general formula (22-1).

(In the general formula (22-1), X represents a group represented by the structural formula (22-A) or the structural formula (22-B). M represents an integer of 1 to 1000. n represents 1 represents an integer of 1 or more. A group of particles including display particles that move in response to an electric field;
A dispersion medium as a dispersion medium for dispersing the particle group;
The charge control material according to claim 1, which is contained in the dispersion medium,
A particle dispersion for display, comprising: A pair of substrates, at least one of which is translucent,
The display dispersion liquid according to claim 8 enclosed between the pair of substrates;
A display medium comprising: A pair of electrodes;
The display dispersion liquid according to claim 8 enclosed between the pair of electrodes,
A display medium comprising: A display medium according to claim 9 or 10,
Voltage applying means for applying a voltage between the pair of substrates of the display medium;
A display device comprising:

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