JP2018205479A - Method for manufacturing electrophoretic display device, electrophoretic display device, and electronic apparatus - Google Patents

Abstract

To provide a method for manufacturing an electrophoretic display device that can prevent a reduction in display quality, an electrophoretic display device, and an electronic apparatus.SOLUTION: A method for manufacturing an electrophoretic display device 100 according to the present invention includes the steps of: producing a mixture containing a solvent and a polymer compound; carrying out solvent adjustment by performing ultrasonic stirring processing such that the weight average molecular weight of the mixture becomes 250,000 or more and 450,000 or less and the degree of dispersion becomes 3.0 or more and 5.0 or less, to produce a first solvent; applying the first solvent to an opposing substrate 2 to form a first sealing film 6; forming partition walls 14 provided on an element substrate 1 and dividing the element substrate into a plurality of cells; supplying fluid dispersion containing electrophoretic particles 31 to the plurality of cells; and arranging the partition walls 14 and first sealing film 6 opposite to each other to seal the fluid dispersion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing an electrophoretic display device, an electrophoretic display device, and an electronic apparatus.

  In recent years, demands for reducing power consumption, thinning and weight reduction, flexibility, etc. of display displays have increased, and electrophoretic display devices have attracted attention. In the electrophoretic display device, two electrode substrates, at least one of which is transparent, are disposed so as to face each other, and a dispersion liquid in which electrophoretic particles are dispersed in a dispersion medium is filled between the opposed electrode substrates. A display is obtained by application.

  Important characteristics of the electrophoretic display device include high reflectivity and quick response. In order to satisfy this characteristic, a structure in which the concentration of the electrophoretic particles with respect to the dispersion medium is constant is necessary. As a method therefor, a configuration using microcapsules encapsulating a dispersion liquid, a configuration in which the dispersion liquid is filled in each region partitioned by partition walls (hereinafter referred to as “partition wall system”), as in Patent Document 1. It has been known. The partition system has advantages such that a space (cell) in which the electrophoretic particles separated by the partition move is wide, the partition structure is strong against the pressing pressure of the display surface, and the display performance is high due to high transparency. In Patent Document 1, a high-quality electrophoretic display sheet having excellent durability, display characteristics, and productivity at low cost and an electrophoretic display medium using the same are provided. A technique is proposed in which the electrophoretic ink layer is sealed by filling the electrophoretic ink and bonding the sealing film on which the adhesive layer is formed to the electrophoretic ink layer, and then curing the adhesive layer. ing.

JP2013-41036A

  The adhesive layer secures hermeticity by biting into the partition walls and prevents leakage of the dispersion and communication between cells. The adhesive layer needs to have both flexibility that allows the partition wall to bite and resilience that adheres to the partition wall, and a resin is used as a forming material. However, the electrophoretic display sheet (electrophoretic display device) described in Patent Document 1 has a problem that it is difficult to suppress the surface roughness of the adhesive layer (sealing film) in the region facing the display region of the display device. It was. In the case where the adhesive layer is formed from a solution containing a resin, the solution tends to have a high viscosity because it has both the flexibility and the resilience described above. Therefore, even if an adhesive layer is formed from the above solution by using a method such as spin coating, screen printing, or die coating, the leveling property of the solution is insufficient and it is difficult to reduce the average surface roughness Ra.

  Here, a phenomenon that easily occurs when the average surface roughness Ra cannot be suppressed will be described with reference to FIGS. 7A and 7B. FIG. 7A is a plan view illustrating a configuration of a cell matrix in a conventional electrophoretic display device, and FIG. 7B is a schematic cross-sectional view taken along B-B ′ of FIG. 7A. As shown in FIG. 7A, in the conventional electrophoretic display device 1000, for example, cells 116 having a square shape in a planar shape are partitioned by partition walls 114 having a square shape in a planar shape, thereby forming a cell matrix 104. Yes.

  As shown in FIG. 7B, in the electrophoretic display device 1000, the counter substrate 102 and the element substrate 101 are disposed to face each other with the partition wall 114, the electrophoretic layer 111, and the like interposed therebetween. An adhesive layer 106 and the like are provided on the surface of the counter substrate 102 that faces the element substrate 101. The electrophoretic layer 111 is partitioned into cells 116 by contacting the tip of the partition wall 114 provided on the element substrate 101 and the adhesive layer 106. Each cell 116 contains a dispersion medium 130 and electrophoretic particles 131 in a sealed state.

  However, when the average surface Ra of the adhesive layer 106 is not suppressed, the adhesion between the tip of the partition wall 114 and the adhesive layer 106 tends to be insufficient. Therefore, like the region C, the adjacent cells 116 communicate with each other, and the dispersion medium 130 and the electrophoretic particles 131 may move beyond the partition wall 114. Thereby, display unevenness may occur in the electrophoretic display device 1000.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  [Application Example 1] A method of manufacturing an electrophoretic display device according to this application example includes a step of producing a mixture containing a solvent and a polymer compound, and the weight average molecular weight of the polymer compound in the mixture is 250,000 or more and 450,000 or less. The step of preparing the first solution by applying an ultrasonic stirring treatment so that the dispersity is 3.0 or more and 5.0 or less, and applying the first solution to the first substrate, A step of forming a sealing film, a step of forming a partition provided on the second substrate and dividing the plurality of cells, a step of supplying a dispersion liquid containing electrophoretic particles to the plurality of cells, a partition, And a step of sealing the dispersion by disposing one sealing film opposite to each other.

  According to this application example, by subjecting the mixture to an ultrasonic stirring treatment, a part of the molecular chain of the polymer compound is broken, the molecular weight is reduced, and the entanglement of the polymer chain of the polymer compound is alleviated. Therefore, the viscosity of the first solution can be reduced as compared with the mixture. By reducing the viscosity of the first solution, the leveling property of the first solution is ensured, and when the first sealing film is formed from the first solution containing the polymer compound, the first sealing film is in-plane. The average surface roughness Ra can be suppressed as compared with the conventional case.

  In the first sealing film before the partition wall bites into the sealing film, the in-plane average surface roughness Ra is suppressed, so that the entire in-plane partition wall bites into the first sealing film more uniformly than before. And the first sealing film are in close contact with each other. For this reason, the sealing property of the cells is improved, leakage of the dispersion liquid and communication between the cells are suppressed, and display defects such as display unevenness are less likely to occur.

  As described above, a method of manufacturing an electrophoretic display device that suppresses the surface roughness (average surface roughness Ra) of the first sealing film on the side in contact with the partition wall, reduces the occurrence of display unevenness, and improves the display quality is provided. can do.

  [Application Example 2] In the method for manufacturing an electrophoretic display device according to the application example described above, the amount of energy applied with ultrasonic waves of ultrasonic stirring is 20 W / per unit solid concentration of the polymer compound in the mixture. It is preferable that they are wt% or more and 300 W / wt% or less.

  According to the above application example, the first sealing film can be prepared in a short time by performing the ultrasonic stirring treatment on the mixture, and the viscosity can be finely adjusted. The desired film thickness can be produced and the effect of suppressing the average surface roughness Ra can be obtained.

  Application Example 3 In the method for manufacturing an electrophoretic display device according to the application example described above, it is preferable that the ultrasonic stirring process has an ultrasonic frequency of 15 kHz to 40 kHz.

  According to this, since the ultrasonic stirring treatment of the mixture can be performed in a short time and the viscosity can be finely adjusted, the target film thickness of the first sealing film can be produced, and the average surface The effect of suppressing the roughness Ra can be obtained.

  Application Example 4 In the method for manufacturing an electrophoretic display device described in the above application example, the solvent preferably dissolves the polymer compound.

  According to this, the polymer compound is dissolved in the solvent and becomes relatively uniformly distributed in the solvent, so that the efficiency of ultrasonic stirring is improved and the molecular weight is easily reduced. Therefore, the time required for the ultrasonic stirring process can be shortened.

  Application Example 5 In the method for manufacturing an electrophoretic display device according to the application example described above, it is preferable that the polymer compound includes epichlorohydrin as a forming material.

  According to this, the polymer compound is produced by ring-opening polymerization of epichlorohydrin, and can include an ether bond derived from epichlorohydrin in the molecular structure. Since this ether bond facilitates the rotational movement of the molecule, the polymer compound is relatively excellent in flexibility. For this reason, the partition walls are more likely to bite into the first sealing film formed from the polymer compound, and the partition walls and the first sealing film can be more closely attached. Therefore, it is possible to provide a method for manufacturing an electrophoretic display device in which leakage of dispersion liquid and communication between cells are further suppressed, display unevenness is reduced, and display quality is improved.

  Application Example 6 An electrophoretic display device according to this application example is disposed between a first substrate, a second substrate disposed to face the first substrate, and the first substrate and the second substrate. Partitions constituting a plurality of cells, a dispersion liquid filled in the plurality of cells and containing electrophoretic particles, a first seal disposed between the partition walls and the first substrate and disposed to face the plurality of cells. A first sealing film having a thickness in the center of the cell of 10 μm or more and 20 μm or less, an average surface roughness Ra of 1 μm or less, and the tip of the partition wall at the center of the cell It is located on the first substrate side from the position.

  According to this application example, since the thickness of the first sealing film is 10 μm or more and 20 μm or less, the partition wall easily bites into the first sealing film. Since the average surface roughness Ra is 1 μm or less, the partition walls and the first sealing film are more likely to adhere more uniformly than in the past. For this reason, the sealing property of the cells is improved, leakage of the dispersion liquid and communication between the cells are suppressed, and display defects such as display unevenness are less likely to occur. As described above, it is possible to provide an electrophoretic display device in which display unevenness is reduced and display quality is improved.

  Application Example 7 In the electrophoretic display device according to the application example described above, the first sealing film preferably has an elastic modulus of 5 MPa or more and 40 MPa or less.

  This makes it easier for the partition wall to bite into the first sealing film, and makes it easier for the partition wall and the first sealing film to be in close contact by the repulsive force derived from elasticity. This makes it easier to maintain the adhesion between the partition walls and the first sealing film against changes in expansion and contraction of the dispersion due to temperature changes. Accordingly, it is possible to provide an electrophoretic display device in which the sealing property of the cell is further improved, the leakage of the dispersion liquid and the communication between the cells are suppressed, the occurrence of display unevenness is reduced, and the display quality is improved. it can.

  Application Example 8 In the electrophoretic display device according to the application example described above, the polymer compound preferably includes epichlorohydrin as a forming material.

  According to this, the polymer compound has an ether bond derived from the epoxy group of epichlorohydrin in the molecular structure. This ether bond is relatively excellent in flexibility because the rotational movement of the molecule is easy. For this reason, the partition walls are more likely to bite into the first sealing film, and the partition walls and the first sealing film can be more closely attached. Accordingly, it is possible to provide an electrophoretic display device in which leakage of the dispersion liquid and communication between cells are further suppressed, display unevenness is reduced, and display quality is improved.

  Application Example 9 In the electrophoretic display device according to the application example described above, it is preferable that a second sealing film is provided between the first sealing film and the partition.

  According to this, by providing the second sealing film between the first sealing film and the partition wall, it is possible to suppress the elution of impurities contained in the first sealing film into the dispersion liquid. . Accordingly, it is possible to provide an electrophoretic display device in which the occurrence of display unevenness is reduced and display quality is improved by suppressing changes in the charge of the dispersion liquid and aggregation of electrophoretic particles.

  Application Example 10 In the electrophoretic display device according to the application example described above, it is preferable that the second sealing film includes vinyl alcohol as a forming material.

  According to this, polyvinyl alcohol (PVA) can be formed using vinyl alcohol as a raw material. By using PVA, since it is difficult to be dissolved by the solvent of the dispersion liquid, it is possible to provide an electrophoretic display device in which display unevenness is reduced and display quality is improved.

  Application Example 11 An electronic apparatus according to this application example includes the above-described electrophoretic display device.

  According to this application example, since the above-described electrophoretic display device is provided, it is possible to provide an electronic apparatus in which deterioration in display quality is suppressed.

FIG. 3 is a cross-sectional view illustrating a schematic configuration of the electrophoretic display device according to the first embodiment. The top view which shows the structural example of a cell matrix. The top view which shows the structural example of a cell matrix. The schematic plan view which shows the planar structure of the frame structure which comprises the display area of an electrophoretic display device. The schematic cross section by the AA 'line arrow of FIG. Sectional drawing which shows the manufacturing process of the sealing film in a counter substrate. Sectional drawing which shows the manufacturing process of the sealing film in a counter substrate. Sectional drawing which shows the manufacturing process of the sealing film in a counter substrate. Sectional drawing which shows the manufacturing process of the sealing film in a counter substrate. Sectional drawing which shows the manufacturing process of an electrophoretic display device. Sectional drawing which shows the manufacturing process of an electrophoretic display device. Sectional drawing which shows the manufacturing process of an electrophoretic display device. Sectional drawing which shows the manufacturing process of an electrophoretic display device. The top view which shows the structure of the cell matrix in the conventional electrophoretic display apparatus. FIG. 7B is a schematic cross-sectional view cut along B-B ′ in FIG. 7A.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the scale of each layer and each member is made different from the actual scale so that each layer and each member can be recognized. Further, the embodiment described below describes an example of the present invention. The present invention is not limited to the following embodiments, and various modifications that are implemented without departing from the spirit of the present invention are also included in the present invention.

(Embodiment 1)
<Electrophoretic display device>
The electrophoretic display device according to the present embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view illustrating a schematic configuration of the electrophoretic display device according to the first embodiment.

  The electrophoretic display device 100 according to the present embodiment includes a counter substrate 2 as a first substrate, an element substrate 1 as a second substrate disposed to face the counter substrate 2, an element substrate 1, and a counter substrate 2. Are provided between the partition wall 14 and the counter substrate 2, and are provided between the partition wall 14 and the counter substrate 2. A first sealing film 6 disposed opposite to the first sealing film 6, wherein the first sealing film 6 has a thickness of 10 μm or more and 20 μm within a plane of a display region constituted by a plurality of cells at the center of the cell. Hereinafter, the average surface roughness Ra is 1 μm or less.

  The electrophoretic display device 100 shown in FIG. 1 includes an element substrate 1, a counter substrate 2, an electrophoretic layer 11 disposed between the element substrate 1 and the counter substrate 2, and a plurality of cells on the element substrate 1. A cell matrix 4 that divides the electrophoretic layer 11 into a plurality of accommodating portions, a counter electrode 7 disposed under the counter substrate 2, a first sealing film 6 disposed under the counter electrode 7, A second sealing film 5 disposed under the first sealing film 6. That is, the second sealing film 5 is provided between the first sealing film 6 and the partition wall 14.

  The tip of the partition wall 14 is located closer to the counter substrate 2 than the center position of the cell. That is, the tip of the partition wall 14 is in close contact with the first sealing film 6 and the second sealing film 5. At this time, since the first sealing film 6 and the second sealing film 5 have elasticity, the portion where the partition wall 14 is bent is bent and deformed, and the portion away from the biting portion is not deformed. That is, the central portion of the cell in the first sealing film 6 refers to a region where there is no deformation due to the biting of the partition wall 14.

  The element substrate 1 includes a base material 1A and pixel electrodes 12 provided on the electrophoretic layer 11 side of the base material 1A. The base material 1A is a substrate made of glass, plastic, or the like, and is not necessarily transparent because it is disposed on the side opposite to the image display surface. The pixel electrode 12 is an electrode in which nickel plating and gold plating are laminated in this order on a Cu foil, or an electrode formed of Al, ITO (indium tin oxide), or the like. Although not shown, a scanning line, a data line, a selection transistor, and the like are formed between the pixel electrode 12 and the substrate 1A.

  The counter substrate 2 is made of a transparent base material such as glass or plastic, and is disposed on the image display side. A counter electrode 7 having a planar shape facing the plurality of pixel electrodes 12 is formed on the electrophoretic layer 11 side of the counter substrate 2. The counter electrode 7 is a transparent electrode formed of MgAg, ITO, IZO (indium / zinc oxide) or the like.

  The electrophoretic layer 11 is composed of a plurality of electrophoretic particles 31 dispersed in a dispersion medium 30. In the present embodiment, the electrophoretic particles 31 include, for example, white particles 31a and black particles 31b.

  The white particles 31a are particles (polymer or colloid) made of a white pigment such as titanium oxide, zinc white, and antimony trioxide, and are used, for example, by being negatively charged. The black particles 31b are particles (polymer or colloid) made of a black pigment such as aniline black or carbon black, and are used, for example, by being positively charged. These pigments include electrolytes, surfactants, metal soaps, resins, rubbers, oils, varnishes, compound charge control agents, titanium-based coupling agents, aluminum-based coupling agents, silanes as necessary. A dispersant such as a system coupling agent, a lubricant, a stabilizer, and the like can be added.

  Moreover, instead of the white particles 31a and the black particles 31b, pigments such as red, green, and blue may be used. According to this configuration, the electrophoretic display device 100 capable of performing color display by displaying red, green, blue, and the like can be provided.

  Examples of the dispersion medium 30 include aliphatic hydrocarbons such as pentane, hexane, and octane, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, benzene, toluene, xylene, hexylbenzene, heptylbenzene, octylbenzene, and nonyl. Aromatic hydrocarbons such as benzenes (alkylbenzene derivatives) having a long chain alkyl group such as benzene, decylbenzene, undecylbenzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene, pyridine, pyrazine, furan, pyrrole, Aromatic heterocycles such as thiophene and methylpyrrolidone, esters such as methyl acetate, ethyl acetate, butyl acetate and ethyl formate, acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, Examples include solvents such as ketones such as hexanone, nitriles such as acetonitrile, propionitrile, acrylonitrile, amides such as N, N-dimethylformamide, N, N-dimethylacetamide, carboxylates, and other various oils. These are used alone or as a mixture.

  A commercially available product may be used as the dispersion medium 30. Examples of such commercially available products include commercially available hydrocarbon solvents such as Isopar E, Isopar G, Isopar H, Isopar L, Isopar M (above, registered trademark) (ExxonMobil). The dispersion medium 30 may be a liquid containing one or more kinds of such commercially available products, or a liquid obtained by mixing one or more of these and the above-described solvent.

  The cell matrix 4 includes, for example, a base 13 and a partition wall 14 disposed on the base 13. The cell matrix 4 is bonded to the element substrate 1 via the adhesive layer 20. Here, the base portion 13 forms the bottom surface of the cell matrix 4 and is formed of a sheet-like (that is, flat plate) member. There is no restriction | limiting in the thickness of the base 13, For example, a thin film about several micrometers-several tens of micrometers may be sufficient. The partition wall 14 forms the side wall of the cell matrix 4 and divides the electrophoretic layer 11 into a plurality of accommodating portions. The partition 14 divides the element substrate 1 into a plurality of spaces (that is, cells), and the electrophoretic layer 11 is disposed in each of the plurality of cells. In the present embodiment, the partition wall 14 has a tapered shape in which the cross-sectional structure tapers toward the distal end side opposite to the base portion 13 side.

The shape of the partition wall 14 in plan view (hereinafter also referred to as a planar shape) is, for example, a square lattice shape, a hexagonal lattice shape, or a triangular lattice shape.
2A and 2B are plan views showing a configuration example of the cell matrix 4. As shown in FIG. 2A, when the planar shape of the partition 14 is a square lattice, the planar shape of the cell 16 is a square. As shown in FIG. 2B, when the planar shape of the partition wall 14 is a hexagonal lattice shape, the planar shape of the cell 16 is a hexagonal shape.

  In addition, in FIG. 1, although the partition 14 has shown the case where it forms integrally with the flat base part 13, this is an example to the last. In the electrophoretic display device 100 of the present embodiment, the partition wall 14 and the flat plate-like base portion 13 may be formed separately, and the partition wall 14 may be fixed on one surface of the flat plate-like base portion 13. Alternatively, the base 13 may be omitted, and the cell matrix 4 may be configured with only the partition walls 14 (in this case, the partition walls 14 may be directly attached to the element substrate 1).

  When the base 13 and the partition 14 are formed integrally, the base 13 and the partition 14 are made of the same material. Moreover, when the base 13 and the partition 14 are formed separately, the base 13 and the partition 14 may be comprised with the same material, and may be comprised with a different material.

  The forming material constituting the base portion 13 may be either a flexible material or a hard material, such as an epoxy resin, an acrylic resin, a urethane resin, a melamine resin, a phenol resin, or the like. Examples include various resin materials and various ceramic materials such as silica, alumina, and titania. However, when plasticity is imparted to the electrophoretic display device 100, a resin material having plasticity is selected for the base portion 13. Moreover, as a forming material which comprises the partition 14, various resin materials, such as an epoxy resin, an acrylic resin, a urethane resin, a melamine resin, a phenol resin, various ceramic materials, such as a silica, an alumina, and a titania, for example. Is mentioned.

  The dispersion medium 30 is hermetically sealed between the cell matrix 4 and the second sealing film 5, thereby preventing leakage of the dispersion and communication between the cells. The change in the ratio of the white particles 31a and the black particles 31b contained in the dispersion medium 30 confined in the cell matrix 4 and the second sealing film 5 can be suppressed, and the charge in the cell can be changed by changing the ratio of the particles. The state changes and the occurrence of display unevenness can be suppressed.

  The first sealing film 6 and the second sealing film 5 are films for sealing the electrophoretic layer 11 in the cell 16. The surface of the first sealing film 6 on the side of the electrophoretic layer 11 is preferably formed with an average surface roughness Ra in the plane of the display region composed of a plurality of cells of 1 μm or less. A second sealing film 5 is formed along the surface of the first sealing film 6 on the electrophoretic layer 11 side. The uneven shape on the surface of the first sealing film 6 on the electrophoretic layer 11 side affects the uneven shape on the surface of the second sealing film 5. Therefore, it is preferable that the average surface roughness Ra in the surface of the display region composed of a plurality of cells on the surface of the second sealing film 5 on the electrophoretic layer 11 side is also 1 μm or less.

  The first sealing film 6 is made of a forming material that is more flexible than the second sealing film 5 described later, and that the top of the partition wall 14 is more easily bite. Therefore, it is preferable that epichlorohydrin is included as a material for forming the first sealing film 6 (polymer compound). In addition, allyl glycidyl ether and ethylene oxide may be included. The elastic modulus of the first sealing film 6 is preferably 5 MPa or more and 40 MPa or less. In this embodiment, an epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (hereinafter also referred to as “GECO”) containing epichlorohydrin, ethylene oxide, and allyl glycidyl ether as a forming material is used as a polymer compound. Using, the 1st sealing film 6 whose elasticity modulus in 20 degreeC is 10 Mpa was formed. In this specification, the elastic modulus refers to an elastic modulus at 20 ° C. unless otherwise specified.

  The elastic modulus of the first sealing film 6 and the like can be obtained by measuring the test force and the compression displacement using a micro compression tester MCT series manufactured by Shimadzu Corporation. Specifically, the compression force is confirmed by changing the test force, and the restoration rate when releasing the compression is confirmed.

  The first sealing film 6 preferably has a weight average molecular weight of 250,000 or more and 450,000 or less and a dispersity of 3.0 or more and 5.0 or less in order to form a flat film. When the weight average molecular weight is 250,000 or more, the thickness of the film during the coating process can be ensured and the in-plane uniformity of the display area composed of a plurality of cells can be improved.

Here, the weight average molecular weight of GECO can be measured by gel permeation chromatography (GPC). For example, GPC (gel permeation chromatography) such as “HLC-8320GPC EcoSEC” manufactured by Tosoh Corporation. Measurement is performed under the following conditions using a measuring apparatus. The weight average molecular weight (Mw) of GECO is calculated as a polystyrene equivalent value from a standard polystyrene (PS) calibration curve obtained by GPC measurement.
Detector: RI detector for liquid chromatogram Measurement temperature: 40 ° C
Solvent: THF (tetrahydrofuran)
Sample concentration: 0.6 mg / ml

  Here, the degree of dispersion of GECO is determined by measuring the weight average molecular weight Mw and the number average molecular weight Mn using gel permeation chromatography (GPC). The degree of dispersion can be calculated, for example, by measuring the number average molecular weight Mn by the same method as the weight average molecular weight Mw of GECO described above and dividing the weight average molecular weight Mw by the number average molecular weight Mn.

  As a material for forming the first sealing film 6, urethane, isoprene, butadiene, chloroprene, styrene / butadiene rubber, or the like may be used.

  The second sealing film 5 is used, for example, to prevent the first sealing film 6 from eluting into the dispersion medium 30. A material for forming the second sealing film 5 is preferably a material that has little interaction with the electrophoretic particles 31 and the dispersion medium 30. Examples of the material for forming the second sealing film 5 include water-soluble polymer compounds, and specific examples include polyvinyl alcohol (also referred to as PVA), gelatin, gum arabic, carboxymethyl cellulose, and chaotic cellulose. One or more of these are used. Among these, it is preferable that the 2nd sealing film 5 contains PVA as a forming material from stability with respect to the dispersion medium 30. FIG. In the present embodiment, the second sealing film 5 is formed using PVA. When the first sealing film 6 is configured using a material that does not elute in the dispersion medium 30, the first sealing film 6 may be configured without providing the second sealing film 5.

  Moreover, as a forming material of the 2nd sealing film 5, it is preferable that it is a high molecular compound with small polarity, For example, polyethylene, a polypropylene, etc. may be used. Since these materials are less likely to elute into the dispersion medium 30, it is possible to reduce the occurrence of problems such as a response delay accompanying an increase in viscosity in the electrophoretic display device 100. Moreover, as a forming material of the 2nd sealing film 5, the thing with low adhesiveness or it does not have is preferable. Thereby, it is possible to prevent the electrophoretic particles 31 from adhering to the second sealing film 5.

  In addition, when a hydrocarbon solvent (for example, Isopar) is selected as the dispersion medium 30 and PVA is selected as the second sealing film 5, there are the following advantages. That is, both hydrocarbon solvents (for example, Isopar) and PVA are inexpensive. For this reason, the manufacturing cost of the electrophoretic display device 100 can be reduced.

  Further, the second sealing film 5 can be formed to be colorless and transparent, and a light transmittance of about 90% can be secured. Since the attenuation of light by the second sealing film 5 is small, the visibility of characters, images, etc. displayed on the screen covered with the second sealing film 5 (that is, an aggregate of a plurality of cells 16) is improved. Can do. Further, since the solubility of the second sealing film 5 with respect to the dispersion medium 30 is extremely low, the second sealing film 5 is not easily eroded by the dispersion medium 30, and the electrophoretic layer 11 is sealed in the cell 16 with high hermeticity. be able to. The thickness of the second sealing film 5 is preferably 200 nm to 600 nm because the resistance value increases when it is configured thick, and cracks may occur when it is configured thin.

  The elastic modulus of the second sealing film 5 is preferably 50 MPa to 600 MPa. By forming the first sealing film 6 and the second sealing film 5 using the material as described above, the top of the partition wall 14 is bent or the second sealing film 5 is damaged. In this case, the partition wall 14 can bite into the second sealing film 5 (the second sealing film 5 and the first sealing film 6 are deformed by the top of the partition wall 14).

  Based on such a configuration, in the electrophoretic display device 100, for example, when voltage is applied between the pixel electrode 12 and the counter electrode 7, the electrophoretic particles 31 (white particles 31a and The black particles 31b) are electrophoresed toward one of the electrodes (pixel electrode 12, counter electrode 7). For example, when the white particles 31a are positively charged, if the pixel electrode 12 is set to a negative potential, the white particles 31a move to the pixel electrode 12 side (lower side) and gather to display black. Thereby, the electrophoretic display device 100 can display a desired image.

  FIG. 3 is a schematic plan view showing a planar structure of a frame structure constituting a display area of the electrophoretic display device. 4 is a schematic cross-sectional view taken along line A-A ′ of FIG. 3. Hereinafter, the structure around the sealing film and the seal portion in the electrophoretic display device will be described with reference to FIGS. 3 and 4. In addition, illustration of an insulating layer, wiring, an electrode, etc. is omitted.

  As illustrated in FIGS. 3 and 4, the electrophoretic display device 100 includes a frame region E <b> 1 so as to surround the display region E. The frame region E <b> 1 is a region that does not contribute to display in the electrophoretic layer 11 and includes the seal portion 15.

  The seal portion 15 is used to dam the dispersion medium 30 so as not to flow outward and to adjust the cell gap, and is disposed so as to surround the outer edges of the element substrate 1 and the counter substrate 2.

  The seal portion 15 is also used to bond and bond the element substrate 1 and the counter substrate 2 together. The viscosity of the sealing material for forming the seal portion 15 is, for example, 300,000 Pa · s to 1,000,000 Pa · s. Preferably, it is about 400,000 Pa · s. By using the sealing material having such a viscosity, the shape of the sealing material is maintained at the time of bonding, and the contact area between the element substrate 1 and the counter substrate 2 can be maintained.

<Method for Manufacturing Electrophoretic Display Device>
Next, a method for manufacturing the electrophoretic display device 100 will be described with reference to FIGS. 5A to 5D and FIGS. 6A to 6D. 5A to 5D are cross-sectional views showing the manufacturing process of the sealing film in the counter substrate. 6A to 6D are cross-sectional views illustrating the manufacturing process of the electrophoretic display device.

  The manufacturing method of the electrophoretic display device 100 according to the present embodiment includes a step of preparing a mixture including a solvent and a polymer compound, a weight average molecular weight of the polymer compound in the mixture of 250,000 to 450,000, and a dispersity of The step of preparing a first solution by applying an ultrasonic agitation treatment so as to be 3.0 or more and 5.0 or less, the first solution is applied, the first solution is applied to the first substrate, and the first sealing film is formed. A step of forming a partition provided on the second substrate and partitioning into a plurality of cells, a step of supplying a dispersion containing electrophoretic particles to the plurality of cells, a partition, and a first sealing film And a step of sealing the dispersion liquid.

  As shown in FIG. 5A, a counter substrate 2 having a counter electrode 7 is prepared. In the present embodiment, a flexible resin substrate is selected as the counter substrate 2 in order to impart flexibility to the electrophoretic display device 100.

  First, in the step of preparing a mixture containing a solvent and a polymer compound, the polymer compound such as GECO described above is dissolved in a solvent to obtain a mixture. An organic solvent such as toluene is employed as the solvent. In this embodiment, GECO is used as the polymer compound, and toluene is used as the solvent. Here, the content of the polymer compound in the mixture may be appropriately adjusted depending on the solubility of the polymer compound in the solvent to be employed. For dissolving the polymer compound in the solvent, a stirring device such as a magnetic stirrer may be used, or the dissolving operation may be performed while heating.

  Next, in the step of preparing the first solution by subjecting the mixture to ultrasonic stirring, the amount of energy applied with ultrasonic waves of ultrasonic stirring is 20 W with respect to the unit solid content concentration of the polymer compound in the mixture. / Wt% or more and 300 W / wt% or less, and the frequency of the ultrasonic wave is 15 kHz or more and 40 kHz or less. As a result, a part of the molecular chain of the polymer compound is broken to reduce the molecular weight, the entanglement of the polymer chain of the polymer compound is relaxed, the weight average molecular weight Mw is 250,000 to 450,000, and the dispersity is It is adjusted to 3.0 or more and 5.0 or less. The amount of energy (Wh / wt%) applied per unit solid content concentration is the ultrasonic output application time (W / wt%) per unit solid content concentration (W / wt%). h) multiplied by the value.

  Next, in the step of applying the first solution to the counter substrate 2 and forming the first sealing film 6, for example, a die coater or a comma coater is used for applying the first solution. At this time, the coating amount of the first solution is adjusted so that the thickness of the formed first sealing film 6 is 10 μm or more and 20 μm or less, and the average surface roughness Ra is 1 μm or less. Thereafter, the counter substrate 2 coated with the first solution is heated to volatilize and dry the solvent in the coated first solution. What is necessary is just to adjust heating temperature according to the boiling point of a solvent, etc., for example, you may be 150 degreeC. Thereby, as shown in FIG. 5B, the first sealing film 6 is formed on the counter substrate 2.

  Next, as shown in FIG. 5C, the second sealing film 5 is formed on the surface of the first sealing film 6. The film formation method of the 2nd sealing film 5 is as follows, for example. PVA is used as a material for forming the second sealing film 5, and PVA is dissolved in water or a hydrophilic solvent (for example, methanol or ethanol) to form a liquid, thereby creating a sealing liquid. Specifically, PVA is dissolved in water or the like to obtain a sealing liquid having a concentration of 3 wt% to 40 wt% (mass percent). Next, this sealing liquid is applied to the surface of the first sealing film 6 using a squeegee or the like. Thereafter, the counter substrate 2 coated with the sealing liquid is heated to volatilize and dry the hydrophilic solvent in the coated sealing liquid. The heating temperature may be adjusted according to the boiling point of the hydrophilic solvent. Thereby, the second sealing film 5 is formed so as to be superimposed on the surface of the first sealing film 6 of the counter substrate 2. Since the second sealing film 5 is made of PVA and is hydrophilic, it is not miscible with the lipophilic dispersion medium 30 of the electrophoretic layer 11. That is, the second sealing film 5 is not easily affected by the dispersion medium 30. As a method for applying the sealing liquid, a spin coater, a die coater, or a comma coater may be used in addition to the squeegee.

  Next, as shown in FIG. 5D, the E2 portion of the end face of the first sealing film 6 and the second sealing film 5 formed on the counter substrate 2 is cut out using a cutter blade or the like. Through the above steps, the counter substrate 2 on which the first sealing film 6 and the second sealing film 5 are formed is manufactured.

  Next, the partition 14 is formed on the element substrate 1, and the cell matrix 4 is formed on the element substrate 1 as shown in FIG. 6A.

  Next, as shown in FIG. 6B, a sealing material for forming the seal portion 15 is applied to the end portion of the element substrate 1. Thereby, the electrophoretic layer 11 (that is, the dispersion liquid having a plurality of electrophoretic particles 31 and the dispersion medium 30) supplied in the next step can be blocked so as not to leak out. Examples of the method for applying the sealing material include various application methods such as a dropping method using a dispenser and an ink jet method (droplet discharge method).

  Next, as shown in FIG. 6C, a dispersion liquid containing the electrophoretic particles 31 and the dispersion medium 30 is supplied into each cell of the cell matrix 4. Examples of the supply of the dispersion liquid into each cell include various methods such as a dropping method using a dispenser, an ink jet method (droplet discharge method), a spin coating method, a dip coating method, and a spray coating method. However, among these, it is preferable to use a dropping method or an inkjet method. According to the dropping method or the ink jet method, the dispersion can be selectively supplied to a desired position (cell), so that waste can be suppressed in the cell and more reliably supplied. .

  In the next step, as shown in FIG. 6D, the partition 14 of the element substrate 1 and the first sealing film 6 (second sealing film 5) of the counter substrate 2 are arranged to face each other to seal the dispersion. Stop. At this time, it is preferable that bubbles do not enter the electrophoretic layer 11 to be sealed. Further, it is preferable that the end of the partition wall 14 is inserted, for example, 2 μm to 10 μm from the lower surface to the upper surface of the second sealing film 5. The electrophoretic display device 100 is manufactured through the above steps.

  As described above in detail, according to the electrophoretic display device 100 and the method for manufacturing the electrophoretic display device 100 of the present embodiment, the following effects can be obtained.

  (1) According to the manufacturing method of the electrophoretic display device 100 of this embodiment, the partition wall 14 bites into the first sealing film 6 and the second sealing film 5, thereby preventing a gap from being formed between the matrix cells. And the dispersion liquid can be prevented from moving to the adjacent cell. At that time, in the first sealing film 6, the thickness of the film is 10 μm or more and 20 μm or less, and the average surface roughness Ra is 1 μm or less, so that the partition wall is further digged into the first sealing film 6. It is possible to further suppress the dispersion liquid from moving to the adjacent cell.

  (2) According to the manufacturing method of the electrophoretic display device 100 of the present embodiment, the first sealing film 6 has an ether bond derived from the epoxy group of epichlorohydrin in the molecular structure, and therefore the rotation of the molecule. Because it is easy to move, it is relatively flexible. For this reason, the partition walls are more likely to bite into the first sealing film 6, and the partition walls 14 and the first sealing film 6 can be more closely attached.

  Hereinafter, examples of the method for manufacturing the electrophoretic display device of the present embodiment and comparative examples will be described, and the effects of the present embodiment will be described more specifically.

  In the examples, the condition that the thickness of the first sealing film 6 is 10 μm or more and 20 μm or less and the average surface roughness Ra is 1 μm or less by ultrasonic stirring treatment of the mixture is shown.

  A mixture was prepared using GECO as a polymer compound and a toluene solvent in which it was dissolved, and a test sample was prepared in the following manner. In order to produce the first sealing film 6 having a thickness of 10 μm or more and 20 μm or less and an average surface roughness Ra of 1 μm or less, the first solution viscosity is adjusted. Viscosity adjustment was performed by using a known ultrasonic device and changing the concentration of the solution to carry out ultrasonic stirring, but the viscosity was adjusted by changing the treatment time. As the ultrasonic device, a device having a SONO CLEANER 200DL manufactured by Kaijo Co., Ltd. and a high frequency output of 200 W (frequency: 38 kHz) is used, but other known ultrasonic devices may be used. For example, an ultrasonic device having a high-frequency output of 200 W (frequency 15 kHz) or 600 W (40 kHz) may be used. Thereby, the ultrasonic output (the ultrasonic output per unit solid content concentration of the polymer compound) with respect to the polymer compound in the mixture was changed in the range of 3 W / wt% to 120 W / wt%. In this experiment, the conditions under which a film having a desired thickness and average surface roughness Ra can be produced were searched by changing the ultrasonic output per unit solid concentration of the polymer compound and the time of ultrasonic stirring treatment.

  The ultrasonic stirring method involves direct irradiation in which a sample is placed directly in a horn type device and irradiating with ultrasonic waves, and a container containing a sample is placed in a standing wave type device, and water is used as a medium from the bottom of the container. There is indirect irradiation that irradiates sound waves, but both can be used.

  The first solution was applied to the counter substrate using SPINCOATER 1H-D7 (MIKASA). The number of rotations of the main spin was arbitrary, and the best conditions that can secure the target film thickness and average surface roughness Ra were used. Next, it dried at 150 degreeC for 30 minutes, and produced the 1st sealing film. About the produced 1st sealing film, thickness and average surface roughness Ra were measured using level | step difference measuring device P-15 (KLA Tencor company). The thickness is an average value in the in-plane φ30 mm of the display area composed of a plurality of cells, and the average surface roughness Ra indicates the maximum and minimum unevenness from the average value of the in-plane thickness. This is the value shown. Table 1 shows the evaluation results of Examples 1 to 4 and Comparative Examples 1 to 6. In addition, each Example and each comparative example are the results of producing and evaluating 10 samples, respectively. Comparative Example 1 is a result of forming the first sealing film without performing the ultrasonic stirring process.

  As shown in Table 1, in Examples 1 to 4, the energy amount [Wh / wt%] applied per unit solid content concentration is 20 Wh / wt% or more and 300 Wh / wt% or less, and the weight average molecular weight Mw. Is 250,000 or more and 450,000 or less, and when the dispersity Mw / Mn is 3.0 or more and 5.0 or less, the thickness is 10 μm or more, 20 μm or less, or 20 μm or more, 30 μm or less, and the average surface roughness Ra A first sealing film having a thickness of 1 μm or less can be produced.

  On the other hand, in Comparative Examples 1 to 3, since the weight average molecular weight Mw was high and the viscosity was high, the desired average surface roughness Ra could not be obtained. For this reason, in Comparative Examples 1 to 3, since the film thickness is large, the resistance value of the first sealing film is high, and a sufficient electric field is not applied to the dispersion liquid, so that display quality may not be ensured. In addition, since the average surface roughness Ra is large, a region in which a bite-in structure cannot be formed occurs in the plane, and a particle lateral flow between cells occurs, which may cause display unevenness. In Comparative Examples 4 to 6, the weight average molecular weight Mw was low, the viscosity of the first solution was too low, and the film thickness was less than 10 μm. Therefore, in Comparative Example 4 to Comparative Example 6, there is a possibility that the depth that the partition wall bites into the first sealing film cannot be sufficiently secured.

  Therefore, the first sealing film having a thickness of 10 μm or more and 20 μm or less and an average surface roughness Ra of 1 μm or less is prepared by performing an ultrasonic stirring process under appropriate conditions as shown in the examples. It was shown that Thereby, by using such a first sealing film, the leakage of the dispersion liquid and the communication between the cells can be further suppressed, the occurrence of display unevenness can be reduced, and the display quality can be improved. A method can be provided.

(Embodiment 2)
<Electronic equipment>
The electronic apparatus of this embodiment includes the electrophoretic display device 100 of the above embodiment. Specific examples of the electronic device include an electronic book, a wristwatch, and electronic paper. Each of these electronic devices includes the electrophoretic display device 100 as a display unit. Thereby, according to the electronic device of this embodiment, generation | occurrence | production of display defects, such as a display nonuniformity, can be suppressed and display quality can be improved.

  The electrophoretic display device 100 can be employed in various other electronic devices. Examples of other electronic devices include display units of electronic devices such as mobile phones and portable audio devices, business sheets such as manuals, textbooks, problem collections, and information sheets.

  DESCRIPTION OF SYMBOLS 1 ... Element substrate, 2 ... Counter substrate, 4 ... Cell matrix, 5 ... 2nd sealing film, 6 ... 1st sealing film, 7 ... Counter electrode, 11 ... Electrophoresis layer, 12 ... Pixel electrode, 13 ... Base , 14 ... partition walls, 15 ... seal part, 20 ... adhesive layer, 30 ... dispersion medium, 31 ... electrophoretic particles, 31a ... white particles, 31b ... black particles, 100 ... electrophoretic display device.

Claims (11)

Producing a mixture comprising a solvent and a polymer compound;
The solution is adjusted by applying an ultrasonic agitation treatment so that the weight average molecular weight of the polymer compound in the mixture is 250,000 or more and 450,000 or less, and the dispersity is 3.0 or more and 5.0 or less. A step of producing
Applying the first solution to the first substrate to form a first sealing film;
Forming a partition wall provided on the second substrate and divided into a plurality of cells;
Supplying a dispersion liquid containing electrophoretic particles to the plurality of cells;
And a step of sealing the dispersion by disposing the partition wall and the first sealing film opposite to each other.   The energy amount to which ultrasonic waves of the ultrasonic stirring treatment are applied is 20 W / wt% or more and 300 W / wt% or less with respect to a unit solid content concentration of the polymer compound in the mixture. Manufacturing method of electrophoretic display device.   3. The method for manufacturing an electrophoretic display device according to claim 1, wherein the ultrasonic stirring treatment has an ultrasonic frequency of 15 kHz to 40 kHz.   The method for manufacturing an electrophoretic display device according to claim 1, wherein the solvent dissolves the polymer compound.   5. The method for manufacturing an electrophoretic display device according to claim 1, wherein the polymer compound includes epichlorohydrin as a forming material. 6. A first substrate;
A second substrate disposed opposite the first substrate;
A partition wall disposed between the first substrate and the second substrate and constituting a plurality of cells;
A dispersion filled in the plurality of cells and containing electrophoretic particles;
A first sealing film provided between the partition wall and the first substrate and disposed to face the plurality of cells;
The first sealing film has a thickness in the center of the cell of 10 μm or more and 20 μm or less in the plane, and an average surface roughness Ra of 1 μm or less,
An electrophoretic display device, wherein a tip of the partition wall is located closer to the first substrate than a center portion of the cell.   The electrophoretic display device according to claim 6, wherein the first sealing film has an elastic modulus of 5 MPa or more and 40 MPa or less.   The electrophoretic display device according to claim 6, wherein the polymer compound includes epichlorohydrin as a forming material.   The electrophoretic display device according to claim 6, wherein a second sealing film is provided between the first sealing film and the partition wall.   The electrophoretic display device according to claim 9, wherein the second sealing film contains vinyl alcohol as a forming material.   An electronic apparatus comprising the electrophoretic display device according to any one of claims 6 to 10.

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