JP2011242471A - Electrophoretic display device and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophoretic display device and a method for manufacturing the device for suppressing decrease in adhesive force and improving structural durability and display durability of the electrophoretic display device even when an upper face of a structural body is adhered to a counter electrode substrate via an adhesive layer.SOLUTION: The method includes steps of: fabricating a plurality of cells comprising an insulating structural body disposed upright on a first electrode substrate; forming a first adhesive layer on an upper face of the structural body; filling the cells with an electrophoretic ink; forming a second adhesive layer on a second electrode substrate; and laminating the first electrode substrate and the second substrate by disposing the first electrode substrate and the second electrode substrate facing each other and adhering the first adhesive layer to the second adhesive layer.

Description

  The present invention relates to an electrophoretic display device capable of reversibly changing a visual state by the action of an electric field or the like, and a method for manufacturing the same.

  In recent years, demands for reducing power consumption, thinning and weight reduction, flexibility, etc. of display displays have been increasing, and electronic paper has attracted attention as one of them. An electrophoretic display device using electrophoretic ink or the like is known as one of such electronic papers. The electrophoretic display device has a configuration in which two electrode substrates, at least one of which is transparent, are arranged so as to face each other, and an electrophoretic ink is provided between the opposed electrodes, thereby forming a display panel. A display is obtained on the transparent electrode surface by applying an electric field to the display panel.

  An electrophoretic display device is a display medium that can obtain a desired display by controlling the direction of an electric field, is low in cost, has a viewing angle as wide as that of a normal printed material, consumes little power, and has a display memory property. It has attracted attention because it has advantages such as However, the electrophoretic particles used in the electrophoretic ink have a problem that the particles are likely to aggregate due to long-term storage, and the particles are unevenly distributed during repeated display. Therefore, there has been proposed a method for suppressing aggregation and uneven distribution of particles by filling electrophoretic ink into a number of finely separated small compartments (cells).

  The small compartment (cell) has a method of forming using microcapsules, embossing, photoresist, etc., but when using a method other than microcapsules, in order to suppress aggregation and uneven distribution of electrophoretic particles, It is necessary to adhere the structure (referred to as a spacer, a column, a rib, or the like) formed on one substrate side with an adhesive or the like so that there is no gap between the other substrate. Therefore, a method has been proposed in which the upper surface of the structure and the counter substrate are bonded via an adhesive (see, for example, Patent Document 1 and Patent Document 2).

JP 2009-251214 A JP 2006-184893 A

  However, when the electrophoretic ink is filled in the cell after forming the adhesive layer on the upper surface of the structure, the adhesive strength of the adhesive layer is reduced by the electrophoretic ink coming into contact with the surface of the adhesive layer formed on the upper surface of the structure. This causes a problem that the two electrode substrates cannot be sufficiently bonded together. In particular, due to this decrease in adhesive force, the two electrode substrates facing each other are easily peeled off and the electrophoretic ink leaks, and there is a gap between the structure and the electrode substrate, resulting in sufficient electricity. Problems arise in the structural durability and display durability of the electrophoretic display device, such as the problem that aggregation of electrophoretic particles and uneven distribution cannot be suppressed.

  Even when an adhesive layer is formed on the electrode substrate facing the structure to be bonded to the upper surface of the structure, the same problem as described above is caused by the electrophoretic ink attached to the upper surface of the structure.

  The present invention has been made in view of such a point, and even when the upper surface of the structure and the counter electrode substrate are bonded via an adhesive layer, a decrease in the adhesive force is suppressed, and the electrophoretic display device is provided. An object of the present invention is to provide an electrophoretic display device with improved structural durability and display durability and a method for manufacturing the same.

  In a first aspect of the present invention, a step of forming a plurality of cells formed of an insulating structure standing on a first electrode substrate, and a first adhesive layer on an upper surface of the structure are formed. A step of filling a cell with electrophoretic ink, a step of forming a second adhesive layer on the second electrode substrate, and a first electrode substrate and a second electrode substrate disposed opposite to each other. A method for manufacturing an electrophoretic display device, comprising: bonding a first electrode substrate and a second electrode substrate by bonding the adhesive layer and the second adhesive layer together. .

  According to a second aspect of the present invention, there is provided the method for manufacturing an electrophoretic display device according to the first aspect, wherein the thickness of the second adhesive layer is made smaller than the thickness of the first adhesive layer. is there.

  According to a third aspect of the present invention, there is provided a first electrode substrate, a plurality of cells formed of an insulative insulating structure provided on the first electrode substrate, and an upper surface of the structure. The first adhesive layer, the second electrode substrate, the second adhesive layer formed on the surface of the second electrode substrate, and the electrophoretic ink filled in the cell, Electrophoresis characterized in that the first adhesive formed on the upper surface and the second adhesive formed on the surface of the second electrode substrate are bonded to each other, and the electrophoretic ink is sealed in the cell. It is a display device.

  According to a fourth aspect of the present invention, there is provided the electrophoretic display device according to the third aspect, wherein the thickness of the second adhesive layer is smaller than the thickness of the first adhesive layer.

  According to the present invention, even when the upper surface of the structure and the counter electrode substrate are bonded via the adhesive layer, the decrease in the adhesive force is suppressed, and the structural durability and display durability of the electrophoretic display device are suppressed. An electrophoretic display device and a method for manufacturing the same can be obtained.

It is a figure explaining an example of the manufacturing method of the electrophoretic display device concerning an embodiment. It is a figure explaining an example of the 1st adhesion layer formation process in the manufacturing method of the electrophoretic display device concerning an embodiment.

  The inventor forms an adhesive layer on both the upper surface side of the structure body formed on the first electrode substrate and the second electrode substrate side and performs bonding so that the upper surface of the structure body The knowledge that it can adhere | attach firmly with the electrode substrate of 2 was acquired. Hereinafter, an example of the electrophoretic display device and the manufacturing method thereof according to the present invention will be described.

  The manufacturing method of the electrophoretic display device described in this embodiment includes a cell formation step of forming a plurality of cells formed of an insulating structure erected on a first electrode substrate, and an upper surface of the structure. A first adhesive layer forming step of forming a first adhesive layer, a step of filling a cell with electrophoretic ink, and a second adhesive layer forming step of forming a second adhesive layer on the second electrode substrate And a bonding step of bonding the first electrode substrate and the second electrode substrate by bonding the first adhesive layer and the second adhesive layer. Below, each process is demonstrated concretely with reference to drawings.

<Cell formation process>
In the cell formation step, a plurality of small chambers (cells 104) each including an insulating structure 103 provided on the first electrode substrate 100 are formed (see FIG. 1A). The plurality of cells 104 are separated from each other by the standing structure 103 and can be provided in various shapes such as a circle, a rectangle (rectangle, square), and a hexagon. In addition, the structure 103 may be referred to as a “rib” or a “spacer”.

  The first electrode substrate 100 may be a substrate having electrodes. For example, the first electrode substrate 100 has a structure in which a first electrode layer 102 is provided on a first base 101 as shown in FIG. An insulating structure 103 can be formed over the layer 102.

The first substrate 101 is made of a transparent inorganic material such as glass, quartz, sapphire, MgO, LiF, or CaF ₂ , an organic polymer film such as fluorine resin, polyester, polycarbonate, polyethylene, or polyethylene terephthalate, or ceramic. Can be formed.

The first electrode layer 102 is made of a transparent conductive material such as ITO, ZnO, SnO ₂ , aluminum (Al), gold (Au), platinum (Pt), copper (Cu), silver (Ag), nickel (Ni ), A metal such as chromium (Cr). Further, conductive polymers such as PODET / PVS and PODET / PSS, and transparent conductive materials such as titanium oxide, zinc oxide, and tin oxide may be used. These materials can be formed by methods such as vapor deposition, ion plating, and sputtering. The shape of the 1st electrode layer 102 can be suitably selected according to the shape of the 2nd electrode layer used as a counter electrode. Note that the first electrode layer 102 may be provided in contact with the first base material 101, or a TFT element or the like may be provided over the first base material 101.

  In the electrophoretic display device, when the first electrode substrate 100 is the front electrode substrate, the first electrode substrate 100 is used to visually recognize the display of characters and the like formed from the electrophoretic ink. The base material 101 and the first electrode layer 102 are preferably formed using a light-transmitting material.

  The structure 103 can be formed using a resin material such as a PET film. For example, a plurality of cells 104 can be formed by laser processing a synthetic resin such as a PET film having a certain thickness to form a shape such as a square, hexagon, or circle. Further, after an insulating layer is formed over the first electrode layer 102, the plurality of cells 104 can be formed by patterning the insulating layer using a photolithography method. In addition, a thermoplastic resin can be formed over the first electrode layer 102, and the cell 104 made of the cross-shaped structure 103 can be formed by a method such as hot embossing.

<First adhesive layer forming step>
In the first adhesive layer formation step, the first adhesive layer 105 is formed on the top surface of the structure body 103 (see FIG. 1B).

  For the first adhesive layer 105, various adhesives such as a thermosetting adhesive, a thermoplastic adhesive, and a photocurable adhesive can be used, and it is particularly preferable to use a thermoplastic adhesive. The thermoplastic adhesive can be fixed only on the upper surface of the structure 103 by cooling after forming the adhesive layer 105 on the upper surface of the structure 103 in a state of being melted or softened by heating. This makes it possible to suppress the inflow of the adhesive into the cell. Furthermore, since it can be melted or softened by heating again after filling with the electrophoretic ink, the substrates can be bonded together in the bonding step.

  Even when a thermosetting adhesive or a photocurable adhesive is used, it is preferable to form the adhesive layer 105 so as to suppress the inflow of the adhesive from the upper surface of the structure 103 into the cell. For example, a method in which the adhesive is fixed to the upper surface of the structure 103 with a minimum amount of heating or ultraviolet irradiation so that the adhesive can be fixed, and then completely bonded and cured by heating or ultraviolet irradiation again in the bonding process. And so on.

  The first adhesive layer 105 can be formed using various methods such as gravure printing, screen printing, ink jetting, transfer, and the like in accordance with the characteristics of the adhesive to be used, and a transfer method is particularly preferable. In the case of using the transfer method, the base material 300 on which the adhesive 302 is formed is peeled after being brought into contact with the upper surface of the structure 103, whereby a part of the adhesive is applied to the surface of the base material 103. Can be transferred to the upper surface. This is because by using the transfer method, the first adhesive layer 105 can be selectively and easily formed on the upper surface of the structure body 103 (see FIG. 2).

<Electrophoretic ink filling process>
In the electrophoretic ink filling step, the electrophoretic ink 106 is filled into the cells 104 formed on the first electrode substrate 100 (FIG. 1C). As a filling method, for example, various methods can be used as long as the ink can be filled in the cell, such as coating using a die coater, printing using screen printing, or ink jet or dispenser filling. Can be used.

  The electrophoretic ink 106 only needs to contain at least one kind of electrophoretic particles. For example, the electrophoretic ink 106 is formed of positively charged white particles, negatively charged black particles, and a dispersion medium in which these particles are dispersed. can do. As the white particles, white pigments such as titanium oxide, white resin particles, or resin particles colored in white can be used. As the black particles, black pigments such as titanium black and carbon black, resin particles colored black, and the like can be used. These particles can be arbitrarily used in various colors as long as the contrast can be displayed, and can be a combination of white and red, white and blue, yellow and black, and the like. Alternatively, only one type of charged particle such as only white particles or only black particles may be used.

<Second adhesive layer forming step>
In the second adhesive layer forming step, the second adhesive layer 203 is formed on the surface of the second electrode substrate 200 (see FIG. 1D).

  The second electrode substrate 200 may be formed of a substrate provided with an electrode. For example, the second electrode layer 200 may be provided on the second base material 201. Note that the second base 201 may be formed using any of the materials shown in the description of the first base 101. The second electrode layer 202 may be formed using any one of the materials described in the description of the first electrode layer 102. In the electrophoretic display device, when the second electrode substrate 200 is a front electrode substrate, the display of characters or the like formed from the electrophoretic ink through the second electrode substrate 200 is visually recognized. The second base 201 and the second electrode layer 202 are preferably formed using a light-transmitting material.

  For the second adhesive layer 203, an adhesive such as a thermosetting adhesive, a thermoplastic adhesive, or a photocurable adhesive can be used. These adhesives can be formed using a gravure printing method, a screen printing method, an ink jet method, a transfer method, a spin coating method, or the like.

  Note that the second adhesive layer 203 may be formed over the entire region of the second electrode substrate 200 corresponding to the entire cell 104 provided in the first electrode substrate 100.

  The second adhesive layer 203 is preferably formed using the same material as the first adhesive layer 105 or a material having an effect of improving adhesiveness with respect to the material of the first adhesive layer 105. Thereby, the adhesiveness of the 1st contact bonding layer 105 and the 2nd contact bonding layer 203 can be improved.

<Lamination process>
In the bonding step, the first electrode substrate 100 and the second electrode substrate 200 are disposed to face each other, and the top surface of the structure body 103 and the second electrode are interposed through the first adhesive layer 105 and the second adhesive layer 203. By attaching the substrate 200, the electrophoretic ink 106 is sealed in the cell 104 (see FIG. 1E).

  When the first adhesive layer 105 provided on the upper surface of the structure 103 and the second adhesive layer 203 provided on the second electrode substrate 200 are bonded, an adhesive layer is formed on both the adhesive surfaces. Therefore, the adhesive force can be improved as compared with the case where the adhesive layer is provided only on the upper surface of the structure 103 or one side of the second electrode substrate 200.

  As the adhesive used for the adhesive layer 105 and the adhesive layer 203, it is desirable to select a material having excellent adhesion to the first electrode substrate 100 and the structure 103, but the first electrode substrate 100 which is an adherend is used. In addition, when electrophoretic ink or its components are directly present on the surface of the structure 103, the adhesive force is significantly reduced. This decrease in adhesion force is due to the fact that the effective adhesion area decreases due to the presence of the electrophoretic particles, and additives such as a surfactant in the electrophoretic ink 106 are added to the first electrode substrate 100 and the structure 103. It is thought to be caused by adhering to the surface.

  According to the present invention, since the adhesive layer is formed on the surfaces of the first electrode base material 100 and the structure body 103 which are adherends in advance, the electrophoretic particles, the surfactant in the electrophoretic ink 106, and the like intervene. And the decrease in the adhesive force can be suppressed. Note that there is a possibility that the electrophoretic particles or the surfactant in the electrophoretic ink 106 may be interposed between the first adhesive layer 105 and the second adhesive layer 203 during the bonding. The adhesive layer 105 and the second adhesive layer 203 are softer than the second electrode substrate 200 and the structure body 103, and the respective adhesive layers are deformed, mixed, or compatible in the bonding process. Thus, sufficient wetting, securing of a contact area, and an anchor effect can be expected.

  When a thermoplastic material is used as the adhesive in the present invention, the thermoplastic material softens at a desired temperature (for example, 100 ° C., etc.), and the higher the temperature, the better the wetting with the base material. Will improve. In addition, some thermoplastic materials have tackiness (tackiness) even at room temperature, and such materials can provide adhesion and adhesion even at temperatures close to room temperature.

In addition, when an ultraviolet curable material is used, the ultraviolet curable material absorbs and cures a desired accumulated light amount (for example, 3000 mJ / cm ² ). For example, the first adhesive layer 105 and the second adhesive layer 203 are formed. Immediately after that, after partially irradiating a part of a desired integrated light amount to make it a semi-cured state, the electrophoretic ink 106 is filled in the cell 104 and a bonding process is performed, whereby the first adhesive layer 105 and the first adhesive In addition to improving the adhesion between the electrode substrate 100 and the second adhesive layer 203 and the structure 103, the bonding process can obtain adhesiveness with a relatively small integrated light amount.

  In the step of FIG. 1, it is preferable that the second adhesive layer 203 has a film thickness as small as possible. This is because if the thickness of the second adhesive layer 203 is large, the driving voltage of the electrophoretic display device increases, and the visibility decreases when the second electrode substrate 200 is used as the front electrode substrate. . On the other hand, from the viewpoint of improving the adhesion between the upper surface of the structure 103 and the second electrode substrate 200, an adhesive layer provided between the upper surface of the structure 103 and the second electrode substrate 200 is formed to a predetermined thickness. The above is preferable. Therefore, in order to improve the adhesive force and suppress an increase in driving voltage, it is preferable to form the first adhesive layer 105 so that the thickness of the first adhesive layer 105 is larger than the thickness of the second adhesive layer 203.

  Next, examples performed for clarifying the effects of the present invention will be described.

<Cell formation process>
After an acrylate resist film was bonded to the first electrode substrate (ITO-PET film) using a vacuum laminator, a structure was formed by a photoresist method.

<First adhesive layer forming step>
On a PET film with a release agent, a thermoplastic adhesive (hot melt resin) diluted with a solvent was applied using a comma roll to a thickness of 12 μm and then dried. Next, the PET film on which the thermoplastic adhesive layer is formed and the first electrode substrate on which the structure is formed are passed through a thermal laminator at 120 ° C. and peeled off in a heated state, whereby PET A part of the thermoplastic adhesive layer formed on the film was transferred to the upper surface of the structure. The film thickness of the thermoplastic adhesive layer formed on the upper surface of the structure was 6 to 8 μm.

<Second adhesive layer forming step>
The thermoplastic adhesive diluted with the solvent was applied and dried on a second electrode substrate (ITO-PET film) using a spin coater so that the film thickness after drying was 1 μm.

<Electrophoretic ink filling process>
After the thermoplastic adhesive formed on the upper surface of the structure and the second electrode substrate is cooled, the electrophoretic ink (white particles (lipophilic surface-treated titanium oxide) is applied to the first electrode substrate using a die coater. , Negatively charged), black particles (acrylic particles colored with carbon black (positively charged), ink composed of normal dodecane (boiling point 216 ° C.)) to apply electrophoretic ink to the cell composed of the structure. Filled.

  Next, a main seal portion was formed on the outer periphery of the portion to which the electrophoretic ink was applied (cell forming portion) using an ultraviolet curable adhesive.

<Lamination process>
The first electrode substrate coated with the electrophoretic ink and the second electrode substrate are bonded again through a thermal laminator, and then the main seal portion formed on the outer periphery of the cell forming portion is irradiated with ultraviolet rays to be cured by ultraviolet rays. An electrophoretic display panel was produced by curing the mold adhesive.

(Comparative Example 1)
Next, a comparative example will be described.

<Cell formation process>
After a 50 μm thick acrylate resist film was bonded to the first electrode substrate (ITO-PET film) using a vacuum laminator, a structure was formed by a photoresist method.

<First adhesive layer forming step>
On a PET film with a release agent, a thermoplastic adhesive (hot melt resin) diluted with a solvent was applied using a comma roll to a thickness of 12 μm and then dried. Next, the PET film on which the thermoplastic adhesive layer is formed and the first electrode substrate on which the structure is formed are passed through a thermal laminator at 120 ° C. and peeled off in a heated state, whereby PET A part of the thermoplastic adhesive layer formed on the film was transferred to the upper surface of the structure. The film thickness of the thermoplastic adhesive layer formed on the upper surface of the structure was 6 to 8 μm.

<Electrophoretic ink filling process>
After cooling the thermoplastic adhesive formed on the upper surface of the structure and the second electrode substrate, by applying electrophoretic ink (same as the example) to the first electrode substrate using a die coater, The cell made of the structure was filled with electrophoretic ink.

  Next, a main seal portion was formed on the outer periphery of the portion to which the electrophoretic ink was applied (cell forming portion) using an ultraviolet curable adhesive.

<Lamination process>
The first electrode substrate coated with the electrophoretic ink and the second electrode substrate are bonded again through a thermal laminator, and then the main seal portion formed on the outer periphery of the cell forming portion is irradiated with ultraviolet rays to be cured by ultraviolet rays. An electrophoretic display panel was produced by curing the mold adhesive.

  That is, the comparative example is different from the above-described example in that a thermoplastic adhesive layer is formed only on the upper surface of the structure (no adhesive layer is formed on the second electrode substrate).

(Evaluation)
<Adhesive strength evaluation>
A structure in which an adhesive is formed and bonded to both the upper surface of the structure and the surface of the second electrode substrate (Example), and a structure in which an adhesive is formed and bonded only to the upper surface of the structure (Comparative Example) ) Was evaluated for adhesive strength.

  The evaluation of the adhesive force was performed in the example (the structure in which the first adhesive layer was formed and the second electrode substrate in which the second adhesive layer was formed), and the comparative example (in which the first adhesive layer was formed). In the structure used in the structure and the second electrode substrate (without the adhesive layer)), (a) no inclusion, (b) intervening dodecane as a solvent, (c) interposing electrophoretic ink, These were pasted together and the adhesive strength was measured. The electrophoretic ink used was that used in the examples and comparative examples. The measurement was performed according to the conditions of JIS K6854 “180 ° T-type peel test”. Specifically, the peeling rate was 50 mm / s, the peeling distance was 70 mm, and 10 mm front and back were excluded from the data. The results are shown in Table 1.

<Evaluation of particle movement>
Each of the electrophoretic display panels produced in the examples and comparative examples was placed vertically (in a state where the electrophoretic display panels were set up vertically with respect to the ground), and +50 V and −50 V voltages were alternately applied between the electrodes of the electrophoretic display panel. The black and white display was switched 10,000 times, and the movement of particles (aggregation and uneven distribution) was visually observed. The results are also shown in Table 1.

  From Table 1, it was found that the example had higher adhesive strength between the upper surface of the structure and the second electrode substrate than the comparative example. Further, in the configuration of the comparative example, particle movement occurred when the electrophoretic display panel was driven, whereas in the structure of the example, particle movement did not occur.

DESCRIPTION OF SYMBOLS 100 1st electrode substrate 101 1st base material 102 1st electrode layer 103 Structure 104 Cell 105 1st contact bonding layer 106 Electrophoretic ink 200 2nd electrode substrate 201 2nd base material 202 2nd electrode Layer 203 Second adhesive layer 300 Base material 302 Adhesive

Claims (4)

Forming a plurality of cells formed of an insulating structure standing on the first electrode substrate;
Forming a first adhesive layer on the top surface of the structure;
Filling the cell with electrophoretic ink;
Forming a second adhesive layer on the second electrode substrate;
The first electrode substrate and the second electrode substrate are disposed by opposing the first electrode substrate and the second electrode substrate to bond the first adhesive layer and the second adhesive layer. And a method of manufacturing the electrophoretic display device.   The method for manufacturing an electrophoretic display device according to claim 1, wherein the film thickness of the second adhesive layer is made smaller than the film thickness of the first adhesive layer. A first electrode substrate;
A plurality of cells formed of a standing insulating structure provided on the first electrode substrate;
A first adhesive layer provided on the upper surface of the structure;
A second electrode substrate;
A second adhesive layer formed on the surface of the second electrode substrate;
An electrophoretic ink filled in the cell,
Electrophoresis in which the first adhesive formed on the upper surface of the structure and the second adhesive formed on the surface of the second electrode substrate are bonded to each other, and the electrophoretic ink is sealed in the cell. Display device. The electrophoretic display device according to claim 3, wherein a film thickness of the second adhesive layer is smaller than a film thickness of the first adhesive layer.

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