JP2014051624A - Dye composition for electrowetting display, and electrowetting display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrowetting display device which exhibits excellent responsiveness during image display and prevents image disorders caused by a back flow phenomenon.SOLUTION: A dye composition for electrowetting display contains a nonpolar solvent and a pigment compound represented by the general formula (1) [where, A represents an aromatic ring and B represents a heterocycle]. The solubility of the pigment compound in the nonpolar solvent at 25°C and 0.1 MPa is 1 mass% or greater.

Description

  The present invention relates to a dye composition for electrowetting display and an electrowetting display device.

  2. Description of the Related Art Conventionally, an optical element that includes a cell containing two or more kinds of liquids that do not mix with each other (for example, two liquids of oil and hydrophilic liquid) and operates (drives) by applying a voltage has been studied. As such an optical element, for example, an optical shutter, a variable focus lens, an image display device, and the like are known. In recent years, in particular, a technique using an electrowetting phenomenon has attracted attention.

  As an example of the technology using the electrowetting phenomenon, the first substrate and the second substrate arranged opposite to each other, a plurality of projections defining a plurality of pixel units, and a pixel unit between two adjacent projections There has been disclosed an electrowetting display including a non-conductive first fluid and a second fluid that is a conductive or polar liquid that is immiscible with the first fluid (see, for example, Patent Document 1).

  Many coloring components used for image display are conventionally known. For example, there are examples in which azo dyes, azomethine dyes, methine dyes, phthalocyanine dyes, pyromethene dyes, anthraquinone dyes and the like are used ( For example, see Patent Document 2).

JP 2009-86668 A US 2012/0092753

  As described above, the electrowetting display is one of display technologies that have recently attracted attention as a kind of image display medium. However, as a display medium that replaces a paper medium or the like, display speed and display at the time of displaying an image are possible. It is required to have various characteristics such as density, discriminability, and fineness of the obtained image.

  Among various characteristics, there is a high demand for display speed (that is, image formability) and discrimination and fineness of displayed images.

  In order to fully develop the density of the image displayed on the electrowetting display, it is necessary to increase the coloring density of the oil responsible for image formation, that is, the density of the color material contained in the oil. In general, dyes are used as coloring materials in oils, but dyes may have poor solubility in non-polar solvents that constitute the oil phase, and the concentration is adjusted to a level suitable for image display while maintaining high display characteristics. It is difficult to increase.

  On the other hand, when a dye having high solubility in a nonpolar solvent is used, the color density of the oil itself is improved, but when the amount of the dye increases, the operating sensitivity (responsiveness) of the oil when a voltage is applied decreases, and the image The formability tends to be significantly impaired.

  Therefore, in order to maintain the image display property of the display to some extent, it is necessary to lower the image quality, and the technology that can achieve both image display properties (that is, image forming properties such as display speed) and image quality so far. The fact is that it has not yet been established.

  The present invention has been made in view of the above, and provides an electrowetting display dye composition and an electrowetting display device that have excellent responsiveness during image display and prevent image disturbance due to a backflow phenomenon. It is an object to achieve this purpose.

The present invention has been achieved based on the following findings. That is,
The colorant contained in the oil phase that contributes to imaging is advantageous in enhancing the display characteristics such as responsiveness that the solubility in a nonpolar solvent that forms the oil phase is high. From the viewpoint of solubility, a dye compound having a symmetric structure tends to be advantageous. However, a carbon in which two rings are bonded with an unsaturated double bond, such as indene, and the unsaturated double bond of each ring is bonded. The structure in which the carbonyl group is present at the carbon atom in the ortho position of the atom is highly soluble in a non-polar solvent. As a result, the responsiveness when it is included in the oil phase and used for image display, and the backflow with voltage applied Excellent phenomenon reduction effect.
Backflow is a phenomenon in which the area of oil that contracts and decreases when it is held in a state where a voltage is applied widens over time.

Specific means for achieving the above object are as follows.
<1> For electrowetting display comprising a nonpolar solvent and a dye compound represented by the following general formula (1) and having a solubility in the nonpolar solvent at 25 ° C. and 0.1 MPa of 1% by mass or more. It is a dye composition.
In the following general formula (1), A and B each independently represent an aromatic ring or a heterocyclic ring.

<2> The dye compound is the electrowetting display dye composition according to <1>, wherein the dye compound has an alkyl group having 4 or more carbon atoms.
<3> The dye compound is a dye composition for electrowetting display according to <1> or <2>, which is a compound represented by the following general formula (2).
In the following general formula (2), R ¹ and R ² each independently represents an alkyl group having 4 to 30 carbon atoms. V ¹ , V ² , V ³ , V ⁴ , V ⁵ , V ⁶ , V ⁷ , V ⁸ , V ⁹ , and V ¹⁰ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, aryloxy Represents a group or a halogen atom.

<4> The alkyl group represented by R ¹ and R ² in the general formula (2) is the dye composition for electrowetting display according to the above <3>, which has a branched structure.
<5> The total amount contains a coloring material of 20% by mass or more based on the total amount of the composition, is represented by the general formula (1), and has a solubility in the nonpolar solvent at 25 ° C. and 0.1 MPa of 1% by mass or more. The dye composition for electrowetting display according to any one of <1> to <4>, wherein a content ratio of a certain coloring compound is 20% by mass or more with respect to a total amount of the coloring material.

<6> A first substrate in which at least a part of at least one surface is conductive, a second substrate disposed so as to face the conductive surface of the first substrate, and the conductivity of the first substrate The hydrophobic insulating film disposed on at least a part of the surface side having a conductive surface, and the above-described <1 provided to be movable on the hydrophobic insulating film between the hydrophobic insulating film and the second substrate > To the electrowetting display dye composition according to any one of the above <5>, and the electrowetting display dye composition between the hydrophobic insulating film and the second substrate. An electrically conductive hydrophilic liquid, and a display unit having
By applying a voltage between the hydrophilic liquid and the conductive surface of the first substrate, and changing the shape of the interface between the electrowetting display dye composition and the hydrophilic liquid, the electro It is a wetting display device.

  ADVANTAGE OF THE INVENTION According to this invention, the dye composition for electrowetting displays and electrowetting display apparatus which were excellent in the responsiveness at the time of an image display, and the image disorder by the backflow phenomenon was prevented are provided.

It is a schematic sectional drawing which shows the state at the time of the voltage OFF of the electrowetting display apparatus which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the state at the time of voltage ON of the electrowetting display apparatus which concerns on embodiment of this invention.

  Hereinafter, the electrowetting display dye composition of the present invention will be described in detail, and embodiments of the electrowetting display device will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments shown below.

  The dye composition for electrowetting display of the present invention is represented by a nonpolar solvent and the following general formula (1), and the solubility in the nonpolar solvent at 25 ° C. and 0.1 MPa is 1% by mass or more. It is comprised using the pigment compound. This dye composition can further comprise various additives such as a surfactant, an ultraviolet absorber and an antioxidant as required.

  The dye composition for electrowetting display of the present invention is used as oil constituting an electrowetting display device as described later. Hereinafter, the dye composition for electrowetting display of the present invention may be simply referred to as “dye composition” or “oil”.

As coloring components used for image display, various dyes and pigments have been used conventionally, and appropriate color materials are used depending on the recording form of the image, the composition and characteristics of the ink used, image characteristics, etc. Is selected. In the display technology using the electrowetting phenomenon, a color material is generally contained in an oil layer (oil phase) using a nonpolar solvent, and image display is performed by moving the oil layer. However, dyes have low solubility in non-polar solvents, and if the solubility cannot be ensured, the responsiveness of the oil layer will decrease, or image disturbance will occur due to backflow when the image is displayed by applying voltage. There are things to do. Such a dye that impairs image formation is not suitable for display using the electrowetting phenomenon. From such a viewpoint, in the dye composition of the present invention,
In particular, as a dye component used for coloring an oil phase in electrowetting technology, a dye compound having a specific symmetric ring structure centered on an unsaturated double bond and having a solubility of 1% by mass or more in a nonpolar solvent. contains. As a result, dye solubility is ensured, image display with excellent responsiveness is possible, and the backflow phenomenon when a voltage is applied is also suppressed. Thus, better image display characteristics can be realized as compared with the conventional electrowetting display.

  Hereafter, each component which comprises the dye composition for electrowetting displays of this invention is explained in full detail.

~ Color material ~
From the viewpoint of displaying a colored image, the dye composition for electrowetting display of the present invention is a coloring compound represented by the following general formula (1) as a coloring material (hereinafter referred to as “specific dye in the present invention”). At least one kind). This dye has a solubility in a nonpolar solvent (eg, n-decane) at 25 ° C. and 0.1 MPa of 1% by mass or more, and is soluble in a nonpolar solvent.
In addition, the specific dye in the present invention is a carbon that is located at the ortho position of a carbon atom in which two aromatic rings or heterocycles are linked by an unsaturated double bond, and the unsaturated double bond of each linked ring is bonded. It is a dye whose atoms have a carbonyl structure, and is a dye exhibiting a cyan color.

  In the general formula (1), A and B each independently represent an aromatic ring or a heterocyclic ring. The dye is not particularly limited as long as the dye contains a structure in which such two rings are connected by an unsaturated double bond in the molecule and is soluble in a nonpolar solvent.

The aromatic rings represented by A and B include a benzene ring and a naphthalene ring.
Moreover, the heterocyclic ring represented by A and B is preferably a 3-membered to 6-membered ring, and the heteroatom includes a nitrogen atom, an oxygen atom, a sulfur atom, and the like. Examples of the heterocyclic ring include a thiophene ring, a pyrrole ring, a pyridine ring, and a furyl ring.
Among the above, A and B are preferably a naphthalene ring, a thiophene ring, and a pyrrole ring, and more preferably a naphthalene ring in terms of solubility and absorption strength.

A and B may be unsubstituted or may have a structure substituted with a substituent. Examples of the substituent when substituted include an alkyl group, an aryl group, an alkoxy group, an aryloxy group, and a halogen atom. These substituents are synonymous with the alkyl group, aryl group, alkoxy group, aryloxy group, or halogen atom represented by V ^{1 to} V ¹⁰ in the following general formula (2), and the preferred embodiments are also the same.

The specific dye in the present invention has a solubility in a nonpolar solvent (for example, normal decane (n-Decane)) at 25 ° C. and 0.1 MPa in terms of responsiveness when an oil phase voltage is applied. And Those having excellent solubility in nonpolar solvents, particularly those in hydrocarbon solvents are preferred. When the solubility is 1% by mass or more, the electrowetting display device is more suitable.
In the following, “solubility in n-decane at 25 ° C. and 0.1 MPa” is also simply referred to as “solubility”.
When the specific dye in the present invention is applied to oil which is a display member for producing a display device that operates on the principle of the electrowetting method, the solubility is more preferably 3% by mass or more, and 5% by mass. % Or more is more preferable. The higher the solubility, the better, but the upper limit is usually about 80% by mass.

The specific dye in the present invention preferably has a structure having an alkyl group having 4 or more carbon atoms. By having an alkyl group having 4 or more carbon atoms in the molecular structure, the solubility in a nonpolar solvent (for example, n-decane) is excellent.
Examples of the alkyl group having 4 or more carbon atoms include a butyl group, a t-butyl group, a pentyl group, a neopentyl group, a hexyl group, a 2-ethylhexyl group, an octyl group, and a dodecyl group, and can be dissolved in a nonpolar solvent. From the viewpoint of properties, it is preferably a branched alkyl group.

  A and B in the general formula (1) may be the same or different, but from the viewpoint of developing better responsiveness, it is preferable that A and B have the same ring structure. .

In addition, the specific dye in the present invention may be a dye that does not have a dissociable group (not including an NH group) such as —SO ₃ H, —PO ₃ H ₂ , —CO ₂ H, and —OH in the molecule. preferable. Since it has no dissociable group, it exhibits good solubility in nonpolar solvents.

  Among the specific dyes in the present invention, a dye compound represented by the following general formula (2) is preferable. In this dye, two naphthalene skeletons are bonded by an unsaturated double bond, and the carbon atom located at the ortho position of the carbon in the ring to which the unsaturated double bond is bonded has a carbonyl structure. Similarly to the above, from the viewpoint of solubility in a nonpolar solvent, it is preferable not to have a dissociable group as a substituent.

  The dye compound represented by the general formula (2) has good solubility in nonpolar solvents (particularly hydrocarbon solvents), and is applied to a display device that operates on the principle of the electrowetting method to display an image. The case response and back flow characteristics are superior. Even when this coloring matter is contained in a nonpolar solvent at a high concentration of 20% by mass or more and a colored solution (oil) is prepared and used for image display, it exhibits excellent responsiveness and low backflow rate. It is preferable in that it can be suppressed. In the case of the electrowetting method, the concentration of the coloring material is generally better as the limit value of the concentration showing excellent responsiveness and backflow rate is higher.

In General Formula (2), R ¹ and R ² each independently represents an alkyl group having 4 to 30 carbon atoms. V ¹ , V ² , V ³ , V ⁴ , V ⁵ , V ⁶ , V ⁷ , V ⁸ , V ⁹ , and V ¹⁰ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, aryloxy Represents a group or a halogen atom.

The alkyl group having 4 to 30 carbon atoms represented by R ¹ and R ² may have any of a linear, branched, or cyclic structure, such as a butyl group, a t-butyl group, or an isobutyl group. Pentyl group, isopentyl group, hexyl group, heptyl group, octyl group, 2-ethylhexyl group, dodecyl group, hexadecyl group, cyclopentyl group, cyclohexyl group, 1-norbornyl group, 1-adamantyl group and the like. Alkyl groups represented by R ¹ and R ² are highly soluble in non-polar solvents, and are therefore branched from the viewpoint of responsiveness when used in an oil layer of an electrowetting display device and prevention of backflow phenomenon. An alkyl group having a structure is preferred. The alkyl group may be further substituted with another substituent, and may be substituted with a halogen atom (for example, a fluorine atom or a chlorine atom), an alkoxy group (for example, methoxy, ethoxy) or the like.
^The number of carbon atoms of the alkyl group represented by R 1, ^{R 2} is more preferably from 4 to 20 carbon atoms, 6 to 12 carbon atoms is more preferred.

The alkyl group represented by V ^{1 to} V ¹⁰ is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 20 carbon atoms, and any structure of linear, branched, or cyclic structure. You may have. Examples of alkyl groups include butyl, t-butyl, isobutyl, pentyl, isopentyl, hexyl, heptyl, octyl, 2-ethylhexyl, dodecyl, hexadecyl, cyclopentyl, cyclohexyl, Examples include 1-norbornyl group and 1-adamantyl group. A preferred alkyl group is an alkyl group having a branched structure.
Among these, from the viewpoints of solubility and absorption strength, an alkyl group having 1 to 12 carbon atoms is more preferable, and a branched alkyl group having 1 to 8 carbon atoms is particularly preferable.

The aryl group represented by V ^{1 to} V ¹⁰ is preferably an aryl group having 6 to 30 carbon atoms, and more preferably an aryl group having 6 to 20 carbon atoms. Examples of the aryl group include a phenyl group and a 2-tolyl group.

The alkoxy group represented by V ^{1 to} V ¹⁰ is preferably an alkoxy group having 1 to 30 carbon atoms, and more preferably an alkoxy group having 1 to 20 carbon atoms. Examples of the alkoxy group include 1-butoxy group, 2-butoxy group, t-butoxy group, dodecyloxy group, 2-ethylhexyloxy group, cycloalkyloxy group (for example, cyclopentyloxy group, cyclohexyloxy group) and the like. It is done. A preferred alkoxy group is an alkoxy group having a branched structure.
Among these, from the viewpoint of solubility, an alkoxy group having 1 to 12 carbon atoms is more preferable, and an alkoxy group having a branched alkyl having 1 to 8 carbon atoms is particularly preferable.

The aryloxy group represented by V ^{1 to} V ¹⁰ is preferably an aryloxy group having 6 to 30 carbon atoms, and more preferably an aryloxy group having 6 to 20 carbon atoms. Examples of the aryloxy group include a phenoxy group and a 2-tolyloxy group.

Examples of the halogen atom represented by V ^{1 to} V ¹⁰ include a fluorine atom and a chlorine atom. Among them, a fluorine atom is preferable in terms of responsiveness.

  Hereinafter, specific examples of the dye compounds represented by the general formulas (1) to (2) will be shown. The present invention is not limited to these specific examples.

  The molecular weight of the specific dye in the invention is preferably from 100 to less than 1,000, and more preferably from 150 to less than 800. When the molecular weight is 100 or more, solubility in a nonpolar solvent can be ensured, and when it is less than 1,000, the absorption strength is high and the responsiveness at the time of image display can be maintained at a level that is not impaired. it can.

  The dye composition for electrowetting display of the present invention may be used alone or in combination of two or more. Therefore, the dye composition of the present invention may be configured to contain one type of the specific pigment in the present invention, or may be configured to include two or more types.

  The total amount of the coloring material containing the specific pigment in the present invention contained in the dye composition for electrowetting display of the present invention is preferably 10% by mass or more based on the total amount of the dye composition. The total amount of the coloring material (including the specific pigment in the present invention) is preferably in the range of 20% by mass or more, more preferably 40% by mass or more, based on the total amount of oil, from the viewpoint of improving the density and clarity of the display image. More preferably, it is the range of 50% by mass or more. When the content ratio of the coloring material contained in the dye composition for electrowetting display is increased, the responsiveness of the dye composition at the time of voltage application is lowered and the backflow phenomenon in the voltage application state is also deteriorated. Tend to decrease. Therefore, the effect of the present invention is particularly achieved in the composition of the dye composition in which the content ratio of the coloring material is 10% by mass or more (preferably 20% by mass or more). The total amount of the color material is preferably 80% by mass or less, more preferably 75% by mass or less, based on the total amount of the dye composition, from the viewpoint of increasing the response speed when the display device is configured. More preferably, it is 70 mass% or less. Especially, as a content rate of the specific pigment | dye in this invention, the case where it is 20 mass% or more with respect to the total amount of the coloring material contained in a dye composition is more preferable. Moreover, as a content ratio in the dye composition of the specific pigment | dye in this invention, 5 mass% or more is suitable with respect to the dye composition whole quantity.

About the density | concentration (C) of the specific pigment | dye in this invention in a dye composition, arbitrary density | concentrations can be selected according to the objective, A dye composition is prepared in arbitrary density | concentrations. When used as a dye for an electrowetting display, the dye is usually at a concentration of 0.2% by mass or more, depending on the required εC value (= ε × C [ε: absorption coefficient of oil]). Used diluted in polar solvent.
Although there is no restriction | limiting in particular about the molar extinction coefficient of the methine dye in this invention, The case where it is 30,000 or more is preferable, Most preferably, it is 50,000 or more. A molar extinction coefficient of 30,000 or more is preferable in that it is easy to achieve both high display performance and responsiveness.

~ Non-polar solvent ~
The dye composition for electrowetting display of the present invention contains at least one nonpolar solvent. The nonpolar solvent refers to a solvent having a small relative dielectric constant (so-called nonpolar solvent). Examples of the nonpolar solvent include aliphatic hydrocarbon solvents such as normal (n-) hexane, normal (n-) decane, dodecane, tetradecane, hexadecane and the like (preferably aliphatic hydrocarbons having 6 to 30 carbon atoms). Solvent), a solvent in which the aliphatic hydrocarbon solvent is substituted with fluorine (for example, fluorocarbon oil), a silicone solvent (for example, silicone oil), and the like. Of these, aliphatic hydrocarbon solvents are preferred.

  The dissolved oxygen in the nonpolar solvent is preferably in the range of 10 ppm or less. When the amount of dissolved oxygen exceeds 10 ppm, it tends to deteriorate and the responsiveness tends to decrease. The smaller the dissolved oxygen content, the better, and more preferably 8 ppm or less.

  The content of the nonpolar solvent in the oil is preferably 30% by mass or more, and more preferably 40% by mass or more based on the total amount of the dye composition (oil). When the content of the nonpolar solvent is 30% by mass or more, more excellent optical shutter characteristics are exhibited. Moreover, the solubility of the dye contained in the dye composition is kept better.

  Further, the electrowetting display dye composition (oil) may contain a solvent other than the nonpolar solvent. In this case, the proportion of the nonpolar solvent in the dye composition is preferably 70% by mass or more, more preferably 90% by mass or more, based on the total amount of the solvent in the dye composition.

~ Various additives ~
The dye composition for electrowetting display of the present invention may contain various additives such as a surfactant, an ultraviolet absorber and an antioxidant as other components, if necessary. When it contains an additive, its content is not particularly limited, but it is usually used at about 20% by mass or less based on the total mass of the oil.

The dye composition for electrowetting display of the present invention may be prepared as a black ink using one kind of dye, or may be prepared as a black ink by mixing a plurality of dyes. .
When a plurality of dyes are used in combination, the combination includes a yellow dye having an absorption wavelength in the range of 400 to 500 nm, a magenta dye having an absorption wavelength in the range of 500 to 600 nm, and a cyan dye having an absorption wavelength in the range of 600 to 700 nm. It is preferable to use a mixture.
“Black” means a property in which the difference between the maximum transmittance and the minimum transmittance among the respective transmittances at 450 nm, 500 nm, 550 nm, and 600 nm is 20% or less. , Preferably 15% or less, particularly preferably 10% or less.

Next, an embodiment of the electrowetting display device of the present invention will be described with reference to FIGS.
As described later, the dye composition for electrowetting display of the present invention described above is a non-conductive oil provided so as to be movable on the hydrophobic insulating film between the hydrophobic insulating film and the second substrate. Used as In the present embodiment, a glass substrate with ITO is provided as the first substrate having conductivity, and decane is used as the nonpolar solvent constituting the oil, and an aqueous electrolyte solution is used as the hydrophilic liquid. .

FIG. 1 shows a state of the electrowetting display device according to the present embodiment when the voltage is off.
As shown in FIG. 1, an electrowetting display device 100 according to the present embodiment includes a conductive substrate (first substrate) 11 and a conductive substrate (second substrate) disposed to face the substrate 11. Substrate 12), a hydrophobic insulating film 20 disposed on the substrate 11, and a region defined by the silicone rubber wall 22 a and the silicone rubber wall 22 b between the hydrophobic insulating film 20 and the substrate 12. A hydrophilic liquid 14 and an oil 16 are provided. A region defined by the silicone rubber wall 22a and the silicone rubber wall 22b between the hydrophobic insulating film 20 and the substrate 12 is configured as a display unit (display cell) that displays an image by the movement of the oil 16.

Conventionally, various studies have been made on electrowetting technology. When a solvent-soluble pigment such as a dye is contained in a non-polar solvent that forms an oil phase, the responsiveness when displaying an image decreases, and the voltage is reduced. The backflow when kept in the applied state tends to deteriorate. This appears more prominently when trying to increase the color density in order to increase the quality of the display image. Various dyes and the like can be applied to the pigment component present in the oil phase. Among them, a pigment compound having a structure in which two rings having a carbonyl group at a predetermined position are connected by an unsaturated double bond ( The specific dye in the present invention is less likely to deteriorate the responsiveness and the back flow characteristics in a voltage application state. for that reason,
Among the various dye compounds, as the dye component used for coloring the oil phase of the electrowetting technique, in particular, the dye compound represented by the general formula (1) described above (the compound represented by the general formula (2)) The electrowetting display device of the present invention provided with a dye composition (oil) containing an organic compound is excellent in display responsiveness when displaying an image, and when a display image is held in a voltage applied state. The effect of suppressing the flow phenomenon is also great. Therefore, more excellent image display characteristics can be exhibited as compared with the conventional case.

  In the electrowetting display device 100 of this embodiment, the substrate 11 includes a base material 11a and a conductive film 11b provided on the base material 11a and having conductivity, and the entire surface of the substrate is conductive. It is configured as shown. Further, the substrate 12 is disposed at a position facing the substrate 11. Similarly to the substrate 11, the substrate 12 includes a base material 12 a and a conductive film 12 b provided on the substrate 12 a and having conductivity, and the entire surface of the substrate is configured to exhibit conductivity. . In this embodiment, the board | substrate 11 and the board | substrate 12 are comprised by the transparent glass substrate and the transparent ITO film | membrane provided on it.

  The base material 11a and the base material 12a may be formed using either a transparent material or an opaque material according to the display form of the apparatus. From the viewpoint of displaying an image, it is preferable that at least one of the base material 11a and the base material 12a has light transmittance. Specifically, it is preferable that at least one of the base material 11a and the substrate 12 has a transmittance of 80% or more (more preferably 90% or more) in the entire wavelength region of 380 nm to 770 nm.

Examples of materials used for the base material 11a and the base material 12a include glass substrates (for example, non-alkali glass substrates, soda glass substrates, Pyrex (registered trademark) glass substrates, quartz glass substrates, etc.), plastic substrates (for example, polyethylene substrates). A phthalate (PEN) substrate, a polyethylene terephthalate (PET) substrate, a polycarbonate (PC) substrate, a polyimide (PI) substrate, or the like), a metal substrate such as an aluminum substrate or a stainless steel substrate, a semiconductor substrate such as a silicon substrate, or the like can be used. Among these, a glass substrate or a plastic substrate is preferable from the viewpoint of light transmittance.
Further, a TFT substrate provided with a thin film transistor (TFT) can also be used as a base material. In this case, a mode in which the conductive film is connected to the TFT (that is, a mode in which the conductive film is a pixel electrode connected to the TFT) is preferable. As a result, a voltage can be applied independently for each pixel, and the entire image display device can be actively driven as in a known liquid crystal display device having TFTs.
The arrangement of the TFT, various wirings, product storage capacity, and the like on the TFT substrate can be a known arrangement. For example, the arrangement described in JP-A-2009-86668 can be referred to.

  The conductive film 11b and the conductive film 12b may be either a transparent film or an opaque film depending on the display form of the device. The conductive film is a film having conductivity, and the conductivity is only required to have electrical conductivity to which a voltage can be applied, and the surface resistance is 500Ω / □ or less (preferably 70Ω / □ or less. More preferably 60 Ω / □ or less, and still more preferably 50 Ω / □ or less).

The conductive film may be either an opaque metal film such as a copper film or a transparent film, but a transparent conductive film is preferred from the viewpoint of providing light transmission and displaying an image. The transparent conductive film preferably has a transmittance of 80% or more (more preferably 90% or more) in the entire wavelength region of 380 nm to 770 nm. Examples of the transparent conductive film include at least indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide, indium oxide, zirconium oxide, zinc oxide, cadmium oxide, and magnesium oxide. A film containing one kind is mentioned. Especially, as a transparent conductive film, the film | membrane containing indium tin oxide (ITO) is preferable at the point of light transmittance and electroconductivity.
The amount of tin oxide in the film containing ITO is preferably in the range of 5 to 15% by mass and more preferably in the range of 8 to 12% by mass in terms of reducing the resistance value.

There is no restriction | limiting in particular as specific resistance of an electrically conductive film, For example, it can be 1.0 * 10 < ^-3 > ohm * cm or less.

  As a preferred mode, a common potential is applied to a plurality of display cells forming display pixels on the conductive film 12b of the substrate 12, while an independent potential is applied to the conductive film 11b of the substrate 11 for each display pixel (display cell). By giving, the form which applies the independent voltage to each display cell (pixel) is mentioned. For this mode, a known liquid crystal display mode can be referred to.

  In the present embodiment, the substrate 12 is disposed as a conductive substrate in the same manner as the substrate 11. However, the substrate 12 may be provided with a conductive film without providing a conductive film. A voltage may be applied to the liquid 14. In this case, there is no restriction | limiting in particular in the structure of the board | substrate 12, For example, the material quoted as an example used for said base material 12a can be used.

  The hydrophobic insulating film 20 is provided over the entire surface of the conductive film 11 b of the substrate 11 and is in contact with at least the oil 16. This hydrophobic insulating film is mainly in contact with oil when no voltage is applied (when images are not displayed), and when the voltage is applied (when images are displayed), the oil moves on the surface. However, the region where the oil no longer exists is in contact with the hydrophilic liquid.

Hydrophobic refers to the property that the contact angle when contacted with water is 60 ° or more, preferably the property that the contact angle is 70 ° or more (more preferably 80 ° or more).
For the contact angle, the method described in “6. Still droplet method” in JIS R3257 “Method for testing wettability of substrate glass surface” is applied. Specifically, using a contact angle measuring device (contact angle meter CA-A manufactured by Kyowa Interface Science Co., Ltd.), water droplets having a size of 20 memories are formed, and water droplets are ejected from the tip of the needle to form a hydrophobic insulating film. It is obtained from the contact angle θ (25 ° C.) when the shape of the water droplet is observed from the viewing hole of the contact angle meter after forming a water droplet by allowing it to come into contact.

“Insulation” of an insulating film means a property having a specific resistance of 10 ⁷ Ω · cm or more, preferably a property having a specific resistance of 10 ⁸ Ω · cm or more (more preferably 10 ⁹ Ω · cm or more). Say.

As the hydrophobic insulating film, an insulating film having an affinity with the oil 16 and having a low affinity with the hydrophilic liquid 14 can be used, but a film generated by moving the oil by repeatedly applying a voltage. From the viewpoint of suppressing deterioration, a film having a crosslinked structure derived from a polyfunctional compound is preferable. Among these, the hydrophobic insulating film is more preferably a film having a crosslinked structure derived from a polyfunctional compound having two or more polymerizable groups. The crosslinked structure is suitably formed by polymerizing at least one kind of polyfunctional compound (with other monomers as necessary).
In this embodiment, it is composed of a copolymer obtained by copolymerizing a 5-membered cyclic perfluorodiene.

A polyfunctional compound is a compound having two or more polymerizable groups in the molecule. Examples of the polymerizable group include a radical polymerizable group, a cationic polymerizable group, and a condensation polymerizable group. Among them, a (meth) acryloyl group, an allyl group, an alkoxysilyl group, an α-fluoroacryloyl group, an epoxy group, − C (O) OCH═CH _{2 and the} like are preferable. Two or more polymerizable groups contained in the polyfunctional compound may be the same or different from each other.
In the formation of the crosslinked structure, the polyfunctional compound may be used alone or in combination of two or more.

  As the polyfunctional compound, known polyfunctional polymerizable compounds (radical polymerizable compounds, cationic polymerizable compounds, condensation polymerizable compounds, etc.) can be used. Examples of the polyfunctional compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, ethoxy as polyfunctional acrylate. 1,6-hexanediol diacrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, propoxylated neopentyl glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, Polypropylene glycol diacrylate, 1,4-butanediol di (meth) acrylate, 1,9-nonanediol diacrylate, tetraethylene glycol diacrylate, 2-n Butyl-2-ethyl-1,3-propanediol diacrylate, dimethylol-tricyclodecane diacrylate, hydroxypivalic acid neopentyl glycol diacrylate, 1,3-butylene glycol di (meth) acrylate, ethoxylated bisphenol A di (Meth) acrylate, propoxylated bisphenol A di (meth) acrylate, cyclohexanedimethanol di (meth) acrylate, dimethylol dicyclopentane diacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylol Propane triacrylate, pentaerythritol triacrylate, tetramethylolpropane triacrylate, tetramethylol methane triacrylate , Pentaerythritol tetraacrylate, caprolactone-modified trimethylolpropane triacrylate, ethoxylated isocyanuric acid triacrylate, tri (2-hydroxyethyl isocyanurate) triacrylate, propoxylate glyceryl triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol Tetraacrylate, ditrimethylolpropane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, neopentyl glycol oligoacrylate, 1,4-butanediol oligoacrylate, 1,6-hexanediol oligoacrylate, trimethylolpropane oligo Acrylate, pentaerythritol ori Examples include goacrylate, urethane acrylate, epoxy acrylate, and polyester acrylate.

  As the polyfunctional compound, in addition to the above, for example, paragraphs 0031 to 0035 of JP-A-2008-181067, paragraphs 0149 to 0155 of JP-A-2008-139378, paragraph 0142 of JP-A-2010-134137 From among the known polymerizable compounds described in ˜0146, a polyfunctional polymerizable compound can be appropriately selected and used.

  The polyfunctional compound preferably has 3 or more polymerizable groups (preferably 4 or more, more preferably 5 or more) in the molecule. Thereby, since the density of the crosslinked structure in the film can be further increased, the deterioration of the hydrophobic insulating film when the voltage application is repeated is further suppressed.

As the polyfunctional compound, a fluorine-containing compound is preferable, and a polyfunctional compound having a fluorine content of 35% by mass or more (preferably 40% by mass or more, more preferably 45% by mass or more) is more preferable. When the polyfunctional compound contains a fluorine atom (particularly, the fluorine content is 35% by mass or more of the molecular weight), the hydrophobicity of the hydrophobic insulating film is further improved. Although there is no restriction | limiting in particular in the upper limit of the fluorine content rate in a polyfunctional compound, For example, an upper limit can be 60 mass% (preferably 55 mass%, more preferably 50 mass%) of molecular weight.
As the fluorine-containing compound which is a polyfunctional compound, for example, the fluorine-containing compounds described in paragraphs 0007 to 0032 of JP-A-2006-28280 can be used.

The polymerization method of the polyfunctional compound is preferably bulk polymerization or solution polymerization.
The polymerization initiation method includes a method using a polymerization initiator (for example, a radical initiator), a method of irradiating light or radiation, a method of adding an acid, a method of irradiating light after adding a photoacid generator, and dehydration condensation by heating. There is a method to make it. These polymerization methods and polymerization initiation methods are described in, for example, Tsuruta Shinji, “Polymer Synthesis Method” revised edition (published by Nikkan Kogyo Shimbun, 1971), Takatsu Otsu and Masato Kinoshita, “Experimental Methods for Polymer Synthesis” ", Chemistry Dojin, 1972, pp. 124-154.

  The hydrophobic insulating film is preferably produced using a curable composition containing a polyfunctional compound. The polyfunctional compound contained in the curable composition may be one type or two or more types, and the curable composition may further contain a monofunctional compound. A known monofunctional monomer can be used as the monofunctional compound.

  The content of the polyfunctional compound in the curable composition (the total content in the case of two or more; the same applies hereinafter) is not particularly limited, but from the viewpoint of curability, the total solid content of the curable composition 30 mass% or more is preferable with respect to a minute, 40 mass% or more is more preferable, and 50 mass% or more is especially preferable. The total solid content means all components excluding the solvent.

It is preferable that the curable composition further contains at least one solvent. Examples of the solvent include ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, benzene, toluene, acetonitrile, methylene chloride, chloroform. Dichloroethane, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, cyclohexanol, ethyl lactate, methyl lactate, caprolactam and the like.
20-90 mass% is preferable with respect to the total mass of a curable composition, and, as for content of the solvent in a curable composition (when it is 2 or more types), 30-80 mass% is preferable. More preferably, 40-80 mass% is especially preferable.

It is preferable that the curable composition further contains at least one polymerization initiator. As the polymerization initiator, a polymerization initiator that generates radicals by the action of at least one of heat and light is preferable.
Examples of the polymerization initiator that initiates radical polymerization by the action of heat include organic peroxides, inorganic peroxides, organic azo compounds, diazo compounds, and the like. Examples of the organic peroxide include benzoyl peroxide, halogen benzoyl peroxide, lauroyl peroxide, acetyl peroxide, dibutyl peroxide, cumene hydroperoxide, and butyl hydroperoxide. Examples of inorganic peroxides include hydrogen peroxide, ammonium persulfate, and potassium persulfate, and organic azo compounds such as 2-azo-bis-isobutyronitrile, 2-azo-bis-propionitrile, 2-azo- Examples of the diazo compound such as bis-cyclohexanedinitrile include diazoaminobenzene and p-nitrobenzenediazonium.

As polymerization initiators that initiate radical polymerization by the action of light, hydroxyalkylphenones, aminoalkylphenones, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, Examples include peroxides, 2,3-dialkyldione compounds, disulfide compounds, fluoroamine compounds, and aromatic sulfoniums.
Examples of hydroxyalkylphenones include 2-hydroxy-2-methyl-1-phenyl-1-propan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 1- [4- (2-hydroxyethoxy) -Phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2 -Methyl-propan-1-one, 1-hydroxydimethylphenyl ketone, 1-hydroxycyclohexyl phenyl ketone.
Examples of aminoalkylphenones include 2-dimethylamino-2- (4-methylbenzyl) -1- (4-morpholin-4-ylphenyl) butan-1-one, 2-benzyl-2-dimethylamino -1- (4-morpholinophenyl) -butanone-1,2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one is included.
Examples of acetophenones include 2,2-diethoxyacetophenone and p-dimethylacetophenone.
Examples of benzoins include benzoin benzene sulfonate, benzoin toluene sulfonate, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether.
Examples of benzophenones include benzophenone, 2,4-dichlorobenzophenone, 4,4-dichlorobenzophenone and p-chlorobenzophenone.
Examples of phosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide.
A sensitizing dye can also be used in combination with these polymerization initiators.

  Although content in particular of a polymerization initiator is not restrict | limited, 0.1-15 mass% is preferable with respect to the total solid of a curable composition, More preferably, it is 0.5-10 mass%, Especially preferably, it is 2 ˜5 mass%.

The curable composition may contain other components as necessary. Examples of other components include inorganic oxide fine particles, silicone-based or fluorine-based antifouling agents, slipping agents, polymerization inhibitors, silane coupling agents, surfactants, thickeners, leveling agents and the like.
When other components are contained, the content thereof is preferably in the range of 0 to 30% by mass and more preferably in the range of 0 to 20% by mass with respect to the total solid content of the curable resin composition. A range of 0 to 10% by mass is particularly preferable.

  The thickness of the hydrophobic insulating film is not particularly limited, but is preferably 50 nm to 10 μm, more preferably 100 nm to 1 μm. When the thickness of the hydrophobic insulating film is in the above range, it is preferable in terms of the balance between the insulating property and the driving voltage.

~ Method of forming hydrophobic insulating film ~
The hydrophobic insulating film can be suitably produced by the following method. That is,
Curability for forming a curable layer by applying a curable composition containing a polyfunctional compound to the surface of the substrate 11 to which conductivity is imparted (in this embodiment, the surface of the conductive film 11b of the substrate 11). It is a method having a layer forming step and a curing step in which the polyfunctional compound in the formed curable layer is polymerized to cure the curable layer. By such a method, a hydrophobic insulating film having a crosslinked structure is formed.

When the hydrophobic insulating film 20 that is a curable layer is formed on the substrate 11, it can be performed by a known coating method or transfer method.
In the case of the coating method, a curable composition is applied (preferably dried) on the substrate 11 to form a curable layer. Examples of the coating method include known methods such as spin coating, slit coating, dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, and extrusion coating. Can be used.
In the case of the transfer method, a transfer material having a curable layer formed using a curable composition in advance is prepared, and the curable layer of the transfer material is transferred onto the substrate 11, thereby being transferred onto the substrate 11. A curable layer is formed. For details of the transfer method, for example, paragraphs 0094 to 0121 of JP-A-2008-202006 and paragraphs 0076 to 0090 of JP-A-2008-139378 can be referred to.

Curing of the curable layer (polymerization of a polyfunctional compound) can be performed, for example, by applying at least one of irradiation with active energy rays (hereinafter also referred to as exposure) and heating.
As active energy rays used for exposure, for example, ultraviolet rays (g rays, h rays, i rays, etc.), electron beams, and X rays are preferably used. The exposure may be performed using a known exposure apparatus such as a proximity method, a mirror projection method, or a stepper method. Exposure amount at the time of exposure, for ^example, be a ^{10mJ / cm 2 ~2000mJ / cm 2} , 50mJ / cm 2 ~1000mJ / cm 2 is preferred.
At the time of exposure, it is possible to obtain a hydrophobic insulating film patterned into a desired pattern by exposing through a predetermined photomask and then developing using a developer such as an alkaline solution. .
The heating can be performed by a known method using a hot plate or a furnace, for example. Although heating temperature can be set suitably, it can be set as 100 to 280 degreeC, for example, and 150 to 250 degreeC is preferable. Although heating time can also be set suitably, it can be set, for example as 2 minutes-120 minutes, and 5 minutes-60 minutes are preferable.

  In the present embodiment, a hydrophilic liquid 14 and an oil 16 are injected between the hydrophobic insulating film 20 and the substrate 12.

  The hydrophilic liquid 14 and the oil 16 are liquids that do not mix with each other, and are separated from each other at the interface 17A or the interface 17B as shown in FIGS. 1 to 2, an interface 17A represents an interface between the hydrophilic liquid 14 and the oil 16 in a voltage-off state, and an interface 17B represents an interface between the hydrophilic liquid 14 and the oil 16 in a voltage-on state. Represent.

The oil 16 is a nonpolar solvent and a nonconductive material that is represented by the general formula (1) described above and contains at least a dye compound having a solubility in the nonpolar solvent at 25 ° C. and 0.1 MPa of 1% by mass or more. The liquid (dye composition for electrowetting display) and the content ratio of the pigment is preferably 10% by mass or more based on the whole oil composition.
The oil is colored by containing a pigment, and when the content ratio of the pigment is 10% by mass or more (preferably 20% by mass or more), the contrast ratio is higher, and the discrimination and clarity are more excellent. An image is obtained. In a composition containing a dye at such a concentration, the responsiveness of oil when a voltage is applied is liable to deteriorate and the image display property is liable to be impaired, but in the present invention, it is represented by the general formula (1) described above. By containing the coloring compound as a color material, the responsiveness of oil is improved, the backflow at the time of voltage application is suppressed, and an electrowetting display device having excellent image display properties can be obtained.

Non-conductive means a property having a specific resistance of 10 ⁶ Ω · cm or more (preferably 10 ⁷ Ω · cm or more).

The oil preferably has a low dielectric constant. The relative dielectric constant of the oil is preferably in the range of 10.0 or less, and more preferably in the range of 2.0 to 10.0. It is preferable that the relative permittivity is within this range in that the response speed is faster than that when the relative permittivity exceeds 10.0, and it can be driven (operated) at a lower voltage.
The relative dielectric constant was determined by injecting oil into a glass cell with an ITO transparent electrode having a cell gap of 10 μm, and measuring the electric capacity of the obtained cell at 20 ° C. using a model 2353 LCR meter (measurement frequency: 1 kHz) manufactured by NF Corporation. It is a value measured at 40% RH.

  The viscosity of the oil is preferably 10 mPa · s or less in terms of dynamic viscosity at 20 ° C. Among these, the viscosity is preferably 0.01 mPa · s or more, and more preferably 0.01 mPa · s or more and 8 mPa · s or less. It is preferable that the viscosity of the oil is 10 mPa · s or less because the response speed is high and the oil can be driven at a lower voltage than when the viscosity exceeds 10 mPa · s. The dynamic viscosity is a value measured by adjusting to 20 ° C. using a viscometer (500 type, manufactured by Toki Sangyo Co., Ltd.).

  It is preferable that the oil does not substantially mix with the hydrophilic liquid described later. Specifically, the solubility (25 ° C.) of the oil in the hydrophilic liquid is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and particularly preferably 0.001% by mass or less.

  The higher the OD (image density) value of the electrowetting display device of the present invention, the better the image discrimination and clarity. Therefore, the OD value at the maximum absorption wavelength of the specific dye in the present invention is preferably 0.5 / μm or more per thickness of the oil layer, more preferably 0.65 / μm or more, and still more preferably 1.0 / μm. That's it.

The hydrophilic liquid 14 is a conductive hydrophilic liquid. The conductivity means a property having a specific resistance of 10 ⁵ Ω · cm or less (preferably 10 ⁴ Ω · cm or less).

The hydrophilic liquid includes, for example, an electrolyte and an aqueous solvent.
Examples of the electrolyte include salts such as sodium chloride, potassium chloride, and tetrabutylammonium chloride. The concentration of the electrolyte in the hydrophilic liquid is preferably 0.1 to 10 mol / L, and more preferably 0.1 to 5 mol / L.
As the aqueous solvent, water and alcohol are suitable, and an aqueous solvent other than water may be further contained. Examples of the alcohol include ethanol, ethylene glycol, glycerin and the like.
The aqueous solvent preferably contains no surfactant from the viewpoint of responsiveness.

  In the electrowetting display device 100, a power source 25 (voltage applying means) for applying a voltage between the conductive film 11b and the conductive film 12b via the hydrophilic liquid 14 and for turning on / off the voltage are provided. The switch 26 is electrically connected.

  In the present embodiment, a voltage (potential) can be applied to the hydrophilic liquid 14 by applying a voltage to the conductive film 12 b provided on the substrate 12. As described above, in this embodiment, the surface of the substrate 12 on the side in contact with the hydrophilic liquid 14 is conductive (the structure in which the ITO film is present as the conductive film on the side of the base 12a in contact with the hydrophilic liquid 14). However, it is not limited to this form. For example, an electrode may be inserted into the hydrophilic liquid 14 without providing the conductive film 12b on the substrate 12, and a voltage (potential) may be applied to the hydrophilic liquid 14 by the inserted electrode.

  Next, the operation (voltage off state and voltage on state) of the electrowetting display device 100 will be described.

As shown in FIG. 1, in the voltage off state, the affinity between the hydrophobic insulating film 20 and the oil 16 is high, so that the oil 16 is in contact with the entire surface of the hydrophobic insulating film 20. When a voltage is applied by turning on the switch 26 of the electrowetting display device 100, the interface between the hydrophilic liquid 14 and the oil 16 is deformed from the interface 17A in FIG. 1 to the interface 17B shown in FIG. At this time, the contact area between the hydrophobic insulating film 20 and the oil 16 decreases, and the oil 16 moves to the end of the cell as shown in FIG. In this phenomenon, a charge is generated on the surface of the hydrophobic insulating film 20 by applying a voltage, and the hydrophilic liquid 14 pushes off the oil 16 that has been in contact with the hydrophobic insulating film 20 by this charge, and the hydrophobic insulating film 20 This is a phenomenon that occurs due to contact.
When the switch 26 of the electrowetting display device 100 is turned off and voltage application is turned off, the state returns to the state shown in FIG.
In the electrowetting display device 100, the operations shown in FIGS. 1 and 2 are repeated.

In the above, the embodiment of the electrowetting display device has been described with reference to FIGS. 1 and 2, but is not limited to this embodiment.
For example, in FIGS. 1 and 2, in the substrate 11, the conductive film 11b is provided over the entire surface of the base material 11a, but the conductive film 11b is provided only on a part of the surface of the base material 11a. It may be. Moreover, in the board | substrate 12, although the electrically conductive film 12b is provided over the whole surface of the base material 12a, the form with which the electrically conductive film 12b was provided only in a part of surface of the base material 12a may be sufficient.

  Further, in the embodiment, the pixel responsible for image display of the electrowetting display device by coloring the oil 16 with a desired color (for example, black, red, green, blue, cyan, magenta, yellow, etc.). Can function as. In this case, the oil 16 functions as an optical shutter that switches between an on state and an off state of the pixel, for example. In this case, the electrowetting display device may be configured in any of a transmission type, a reflection type, and a transflective type.

In addition, the electrowetting display device according to the present embodiment may have an ultraviolet cut layer on the outer side (opposite the surface facing the oil) of at least one of the first substrate and the second substrate. Thereby, the light resistance of a display apparatus can further be improved.
A well-known thing can be used as an ultraviolet cut layer, for example, the ultraviolet cut layer (for example, ultraviolet cut film) containing a ultraviolet absorber can be used. The ultraviolet cut layer preferably absorbs 90% or more of light having a wavelength of 380 nm.
The ultraviolet cut layer can be provided by a known method such as a method of attaching an adhesive to the outside of at least one of the first substrate and the second substrate.

  In the electrowetting display device, the structure shown in FIG. 1 (a region (display cell) in which the space between the hydrophobic insulating film 20 and the substrate 12 is partitioned in a lattice shape by a silicone rubber wall 22a and a silicone rubber wall 22b), for example. An image can be displayed by setting one display pixel and arranging a plurality of display cells in a two-dimensional direction. At this time, the conductive film 11b may be a film patterned independently for each pixel (display cell) (for example, in the case of an active matrix image display device), or a plurality of pixels (display cells). Alternatively, the film may be patterned in a stripe shape across the substrate (for example, in the case of a passive matrix image display device).

The electrowetting display device 100 uses a substrate having optical transparency such as glass or plastic (polyethylene terephthalate, polyethylene naphthalate, etc.) as the base material 11a and the base material 12a, and the conductive films 11b and 12b and the hydrophobic insulation. By using a light-transmitting film as the film 20, a transmissive display device can be obtained. In the pixel of the transmissive display device, a reflective display device can be provided by providing a reflection plate outside the display cell.
In addition, for example, a film having a function as a reflection plate (for example, a metal film such as an Al film or an Al alloy film) is used as the conductive film 11b, or a substrate having a function as a reflection plate as the base material 11a ( For example, by using a metal substrate such as an Al substrate or an Al alloy substrate, a pixel of a reflective image display device can be obtained.

  Other configurations of the display cell and the image display device that constitute the electrowetting display device 100 of the present embodiment are disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-86668, Japanese Patent Application Laid-Open No. 10-39800, Special Table 2005-517993, and Japanese Patent Application Laid-Open No. 2004. -252444, JP-A-2004-287008, JP-T-2005-506778, JP-T-2007-531917, JP-A-2009-86668, and the like. Reference can also be made to the structure of a known active matrix type or passive matrix type liquid crystal display device.

  In addition to display cells (display pixels), the electrowetting display device uses the same members as known liquid crystal display devices, such as a backlight, a spacer for adjusting a cell gap, and a sealing material for sealing. Can be configured. At this time, the oil and the hydrophilic liquid may be provided by, for example, applying to the region partitioned by the silicone rubber wall on the substrate 11 by an ink jet method.

The electrowetting display device 100 of the present embodiment includes, for example, a substrate preparation step for preparing the substrate 11, a step for forming the hydrophobic insulating film 20 on the conductive surface side of the substrate 11, and a hydrophobic insulating film for the substrate 11. 20, a partition forming step for forming a partition partitioning on the formation surface, an applying step for applying the oil 16 and the hydrophilic liquid 14 to the regions partitioned by the partition (for example, by an ink jet method), and the substrate 11 after the applying step A cell forming step of forming a cell (display unit) by superimposing the substrate 12 on the side to which the oil 16 and the hydrophilic liquid 14 are applied, and, if necessary, bonding the substrate 11 and the substrate 12 around the cell. And a sealing step for sealing the cell. Adhesion between the substrate 11 and the substrate 12 can be performed using a sealing material usually used for manufacturing a liquid crystal display device.
In addition, a spacer forming step for forming a cell gap adjusting spacer may be provided after the partition wall forming step and before the cell forming step.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1
-1. Preparation of coloring solution
The following dye compounds P-1 to P-2 (the dye compound represented by the general formula (1) described above) and the dye compounds H-1 to H-3 for comparison, and normal decane (n -Decane) were mixed to prepare 5 kinds of 10% by mass normal decane solutions (colored compositions). The obtained normal decane solution was heated at 50 ° C. and then allowed to stand at room temperature for 12 hours to obtain a supernatant. By measuring the amount of undissolved dye, the solubility of each pigment in normal decane at 25 ° C. and 0.1 MPa was calculated. The solubility is shown in Table 1 below.

  As shown in Table 1, the compounds P-1 to P-2 included in the dye compound represented by the general formula (1) exhibit high solubility in normal decane which is a hydrocarbon solvent, and decane. Thus, a dye ink that was well dissolved in the ink was obtained. Therefore, the compounds P-1 and P-2 are suitable for manufacturing a display portion that operates on the principle of the electrowetting method.

-2. Test cell fabrication
On the surface of the ITO film of a glass substrate (10 mm × 10 mm) with an indium tin oxide (ITO) film having a thickness of 100 nm as a transparent electrode, a fluoropolymer (trade name: Cytop, manufactured by Asahi Glass Co., Ltd., model number CTL-809M) The film was applied to a thickness of 600 nm, and a fluoropolymer layer was formed to form a hydrophobic insulating film. Subsequently, a tetrahedron of 8 mm × 8 mm × 50 μm size is cut out from the center of this fluoropolymer layer from the center of 1 cm × 1 cm size silicone rubber (50 μm thick sealing material; Sirius (trade name) manufactured by Fuso Rubber Co., Ltd.). A display part was formed by placing a frame-shaped silicone rubber wall. Inside the silicone rubber wall, the dye ink prepared as described above was injected to a thickness of 4 μm. On the injected dye ink, ethylene glycol was injected to a thickness of 46 μm. From above, a glass substrate with an ITO film was further placed and fixed so that the ITO film faced the dye ink and the aqueous electrolyte solution. In this manner, an electrowetting test cell having the structure shown in FIG. 1 was produced.

-3. Evaluation-
A 100 V DC voltage is applied to each ITO film (transparent electrode) of the two glass substrates with ITO film by a signal generator (a negative voltage is applied to the ITO electrode on the side where the fluoropolymer layer (hydrophobic insulating film) is formed). And the display cell (display cell 30 in FIG. 2) was observed. The dye ink moved in one direction on the surface of the fluoropolymer layer, and the area covering the fluoropolymer layer was reduced. confirmed. The responsiveness of the dye ink at this time and the degree of the backflow phenomenon when the voltage ink was held as it was applied were evaluated. The results are shown in Tables 2 to 4 below.

For area reduction by voltage application, the area shrinkage rate [%] calculated by the following formula (1), and for the backflow phenomenon, by the backflow ratio [%] calculated by the following formula (2), respectively. evaluated.
a) Response time [msec] = Time required to start voltage application from a voltage non-applied state and reach the most contracted state from the time of application b) Area shrinkage ratio [%] = (Dye ink when contracted most) Area) / (area of dye ink before voltage application) × 100 (1)
c) Backflow ratio [%] = (Area of dye ink after 5 seconds in voltage application state) / (Area of dye ink when contracted most) × 100 (2)
The OD (image density) was evaluated by measuring the OD value at the maximum absorption wavelength of the dye using a spectroradiometer SR-3 manufactured by TOPCOM. The OD value is a value per 1 μm thickness of the oil layer.

  As shown in Tables 2 to 4, although a difference appears in the degree of the effect expressed by the dye concentration, the display device configured using the dye compound represented by the general formula (1) has good responsiveness. In addition, the backflow phenomenon after image display (voltage application state) was suppressed to a small level.

(Example 2)
A compound P-1 (hereinafter referred to as cyan dye P-1), which is a dye compound represented by the general formula (1), is used as a cyan dye. This compound P-1, yellow dye Y-1 having the following structure, orange Dye O-1 and magenta dye M-1 were mixed to prepare black ink B-1 having the following composition.
<Black ink B-1 composition>
・ Yellow dye Y-1 ... 5mg
・ Orange dye O-1 ... 6mg
・ Magenta dye M-1 ... 11mg
・ Cyan dye P-1 ... 18mg
・ Normal decane ... 60mg

  Next, in the same manner as in Example 1, an electrowetting test cell was produced and evaluated. The results are shown in Table 5 below.

  As shown in Table 5, as in Example 1, high responsiveness was exhibited, and the backflow phenomenon after image display (voltage application state) was suppressed to a small level.

DESCRIPTION OF SYMBOLS 11 ... 1st board | substrate 11a, 12a ... Base material 11b, 12b ... ITO film 12 ... 2nd board | substrate 14 ... Hydrophilic liquid 16 ... Oil 17A, 17B ... Interface 20 between hydrophilic liquid and oil ... hydrophobic insulating films 22a, 22b ... silicone rubber wall 30 ... display cell 100 ... electrowetting display device

Claims (6)

A dye composition for electrowetting display, comprising: a nonpolar solvent; and a dye compound represented by the following general formula (1) and having a solubility in the nonpolar solvent at 25 ° C. and 0.1 MPa of 1% by mass or more: .

[Wherein, A and B each independently represents an aromatic ring or a heterocyclic ring. ]   The dye composition for electrowetting display according to claim 1, wherein the pigment compound has an alkyl group having 4 or more carbon atoms. The dye composition for electrowetting display according to claim 1 or 2, wherein the pigment compound is a compound represented by the following general formula (2).

[Wherein, R ¹ and R ² each independently represents an alkyl group having 4 to 30 carbon atoms. V ¹ , V ² , V ³ , V ⁴ , V ⁵ , V ⁶ , V ⁷ , V ⁸ , V ⁹ , and V ¹⁰ are each independently a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, aryloxy Represents a group or a halogen atom. ] The dye composition for electrowetting display according to claim 3, wherein the alkyl group represented by R ¹ and R ² in the general formula (2) has a branched structure.   The total amount of the coloring material is 20% by mass or more with respect to the total amount of the composition, and the content ratio of the coloring compound is 20% by mass or more with respect to the total amount of the coloring material. 2. A dye composition for electrowetting display according to item 1. A first substrate having at least a portion of at least one surface conductive;
A second substrate disposed opposite the conductive surface of the first substrate;
A hydrophobic insulating film disposed on at least a part of a surface side having a conductive surface of the first substrate;
The dye composition for electrowetting display according to any one of claims 1 to 5, wherein the dye composition is provided between the hydrophobic insulating film and the second substrate so as to be movable on the hydrophobic insulating film. When,
A conductive hydrophilic liquid provided in contact with the electrowetting display dye composition between the hydrophobic insulating film and the second substrate;
A display unit having
An image is obtained by applying a voltage between the hydrophilic liquid and the conductive surface of the first substrate to change the shape of the interface between the electrowetting display dye composition and the hydrophilic liquid. Electrowetting display device to display.