JP4389453B2 - Manufacturing method of display device - Google Patents

Description

【００９０】
これらの結果より、各実施例で得られた表示装置は、平均的なコントラストが２以上であり、特に実施例１〜４の表示装置は、概ね１０以上のコントラストを達成しており、実施例５〜８に対して優位であることが確認された。なお、実施例１で得た表示装置は、輝度の測定点の９０％以上で１０以上の値を示した。また、表示面を垂直にたてた状態で、１万回の白黒反転表示を行ったところ、画面全体の表示は均一であり、表示ムラは認められなかった。
【００９１】
【発明の効果】
以上説明したように、本発明の表示装置の製造方法によれば、十分な視認性を確保しつつ製造工程を簡略化して経済性を向上できる表示装置を得ることができる。
【図面の簡単な説明】
【図１】本発明による表示装置の製造方法で得られる表示装置の好適な一実施形態を示す模式断面図である。
【図２】図１におけるII−II線に沿った模式断面図である。
【図３】（Ａ）〜（Ｄ）は、本発明の製造方法により表示装置１００を製造している状態を示す工程図である。
【図４】（Ａ）〜（Ｄ）は、本発明の製造方法により表示装置１００を製造している状態を示す工程図である。
【符号の説明】
１…基板、２…下部電極層、３…分散系溶液相、４ａ…バインダー液滴、４ｂ，４ｃ…固化バインダー、４…隔壁、５…平坦化層、６…上部電極層、７…上部保護層、１０ａ，１０ｂ…泳動粒子（粒子体）、１００…表示装置、Ｖ…紫外線。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a display device, and more specifically, a display device that performs display based on a change in a spatial distribution state of a plurality of particle bodies in a dispersion solution in which a plurality of particle bodies are dispersed in a solvent, for example, The present invention relates to a method for manufacturing a display device usable as electronic paper.
[0002]
[Prior art]
Electronic paper is positioned between conventional paper display (so-called “hard copy”) and electronic display typified by CRT, liquid crystal, etc. (so-called “soft copy”). Is expected. Unlike electronic display devices, electronic paper is required to be able to maintain a screen once displayed (images, characters, etc.) without power (self-holding property). In particular, even if a viewer looks at the display screen for a long time, there is little fatigue and high visibility (contrast) equivalent to a printed matter is desired.
[0003]
Conventionally, techniques such as rotation of colored particles, electrophoresis, thermal rewritable, liquid crystal, and electrochromy are known as methods for displaying images and characters on such electronic paper. Among these, an electrophoretic display device using an electrophoretic phenomenon is excellent in various points such as contrast, self-holding property, and drive current. An electrophoretic display device basically has two substrates, at least one of which is transparent, facing each other, and a dispersion solution in which electrophoretic particles are dispersed in an organic solvent (dispersion solvent) is held between the substrates. Has a structure. Electrodes are provided on the opposing surfaces of the respective substrates.
[0004]
In such an electrophoretic display device, an electric field is generated between the substrates when a voltage is applied between the electrodes. The electrophoretic particles in the dispersion solution are attracted to or separated from the display surface side by the action of the electric field, and as a result of changing the spatial distribution state, the reflectance of the display surface changes. Therefore, it is possible to display a required figure or character by controlling the applied voltage and thus the electric field. An apparatus that forms an electric field using an external device without providing an electrode on a substrate is also known.
[0005]
Further, for example, Patent Document 1 discloses an electrophoretic display device having an upper substrate formed so that the upper electrode has a curved structure. In this apparatus, the upper substrate naturally plays the role of a concave lens, and when observing from the upper substrate side, the lower electrode can appear smaller, thereby improving the contrast. Therefore, even if a transparent solution containing no dye material is used as the dispersion solution in which the electrophoretic particles are dispersed, the contrasting color of the electrophoretic particles (for example, the opposite colors in the hue ring of the Ostwald system, By forming a colored layer expressing the vertex colors in the same hue triangle of the system, sufficient contrast and a sufficiently fast response speed can be obtained.
[0006]
Furthermore, Patent Document 2 describes an electro-magnetic optical device using a guide medium in which microcapsules containing fine particles are dispersed and a light control film that changes the light transmittance by applying an electric field to the fine particles. Yes. In this device, a large number of minute microcapsules are randomly arranged in the guiding medium.
[0007]
[Patent Document 1]
JP 2001-174853 A
[Patent Document 2]
JP 63-303325 A
[0008]
[Problems to be solved by the invention]
However, although these display devices are expected to be widely used as electronic papers such as electronic newspapers and electronic magazines, their manufacturing methods are complicated, the number of processes increases, and the throughput can be sufficiently increased. It tends to be impossible. Specifically, in order to prevent the uneven distribution of the dispersion system, not only the process of encapsulating in the microcapsule, but also the production of 'cells' and 'indents' that enclose the dispersion system requires complicated and time-consuming fine processing. Necessary. Therefore, it is still expensive from a commercial point of view, and its use like a conventional “paper” is not realistic at present. Therefore, realization of a cheaper display device is desired.
[0009]
Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for manufacturing a display device that can improve the economy by simplifying the manufacturing process while ensuring sufficient visibility.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, the display device manufacturing method according to the present invention performs display by changing the spatial distribution state of a plurality of particles in a dispersion solution in which a plurality of particles are dispersed in a solvent. A method of manufacturing a display device, comprising: a first step of supplying a dispersion solution in a droplet state onto a substrate; and a binder component on the substrate on which the dispersion solution is applied and insoluble in a solvent. A second step of supplying a certain binder liquid in a droplet state and a third step of solidifying the binder component in the binder liquid applied on the substrate or the binder liquid itself are characterized.
[0011]
Note that “insoluble” in the second step indicates that the dispersion solution and the binder liquid are not substantially compatible with each other, but in reality, it is difficult to think of a combination of liquid phases that are strictly incompatible ( That is, the solubility in one of the other cannot be completely 0). In the present invention, the solubility of the binder liquid in the dispersion solution or the solvent constituting the binder liquid is 1% by volume or less at room temperature. . If the solubility is 1% by volume or less, no substantial adverse effect is observed. On the other hand, if the solubility exceeds 1% by volume, the viscosity of the dispersion solution rises to an unfavorable level, and the migration of the particles as electrophoretic particles The speed tends to decrease, and may move to the binder liquid phase of the particles. Further, the “binder component” can fix the dispersion solution on the substrate when it is solidified, and in the present invention, includes the case where the “binder component” itself is a “binder liquid”. .
[0012]
In such a method, the dispersion solution supplied in the first step is applied onto the substrate, and the droplets are convexly covered on the substrate according to the difference in interfacial tension between the substrate and the dispersion solution. Worn. Next, in the second step to be performed, the binder liquid is also supplied in the form of liquid droplets onto a large number of liquid droplets having such a convex shape and applied onto the substrate. The binder liquid is insoluble in the dispersion solution, and both are phase-separated into two layers. At this time, since both are in a liquid phase (liquid-liquid system), the droplets of the binder liquid can be deposited so as to cover the droplets of the dispersion solution. Thus, the liquid droplets of the individual dispersion solutions are held and fixed on the substrate in a state of being fractionated by the binder liquid.
[0013]
Next, in the third step, when the binder liquid or the binder component contained therein is solidified, the binder liquid that has been deposited so as to cover the droplets of the dispersion solution is fixed to the part, and the partition wall is formed. The dispersion solution is formed and sealed between the partition wall and the substrate while maintaining the shape of the convex droplet. Due to the binding action of the binder component, the droplets of the individual dispersion solutions are reliably isolated from each other and sufficiently stabilized without using conventional microcapsules or the like. In order to solidify the binder liquid itself, it is preferable to cure the entire liquid, and in order to solidify the binder component in the liquid, other components (for example, a solvent, etc.) holding the binder component in a liquid state are used. The process to remove is preferable and you may combine both processes.
[0014]
In the first step, the dispersion solution is preferably supplied onto the substrate so that the average particle size of the droplets of the dispersion solution is 10 to 100 μm.
[0015]
In this way, the height of the droplets of the dispersion solution deposited on the substrate can be sufficiently increased, and as a result, good contrast can be obtained and display quality (resolution) degradation can be sufficiently suppressed. Is done.
[0016]
Furthermore, in the second step, it is more preferable to use a binder liquid having a specific gravity lower than that of the dispersion solution.
[0017]
This causes a difference in specific gravity between the dispersion solution and the binder liquid, and the binder liquid phase is separated from the dispersion solution phase when the dispersion solution droplets and the binder liquid are phase-separated in the second step. It becomes easy to be maintained in a state. At this time, since the binder liquid has a lower specific gravity than the dispersion solution, the binder liquid phase is easily held on the dispersion solution phase of the convex droplets. Therefore, the sealing performance of the dispersion solution when the solidification process is performed in the third step is reliably improved. Here, the specific gravity difference between the binder liquid and the dispersion solution is more preferably 0.1 or more, and particularly preferably 0.2 or more.
[0018]
In the second step, it is preferable that the binder liquid is supplied onto the substrate so that the average particle diameter of the droplets of the binder liquid is 1/5 or less of the average particle diameter of the droplets of the dispersion solution. Although there is no particular need to limit the lower limit of this ratio, it can be said that about 1/100 is practical. By setting the value of this ratio to 1/5 or less, it is possible to prevent the partition wall formed by solidifying the binder liquid in the third step from becoming excessively thick compared to the dispersion solution phase.
[0019]
Furthermore, it is more preferable that the second step and the third step are repeated a plurality of times in that order.
[0020]
By doing this, the amount of binder liquid applied at one time can be suppressed, and the binder liquid is unevenly distributed due to the surface tension in each second step as compared with the case where the second and third steps are performed only once. Is suppressed. As a result, compared with the case where the second and third steps are performed only once, the thickness of the partition wall for sealing the finally formed dispersion solution is reduced.
[0021]
Specifically, in the first step, it is more preferable to use a fluorinated solvent as the solvent contained in the dispersion solution.
[0022]
Fluorinated solvents are chemically stable and tend to be poorly compatible with many other organic solvents. Therefore, when using organic substance for a binder liquid, the choice of the binder liquid can be expanded, in other words, the versatility of the material used is improved. Further, many of the fluorine-based solvents have a high specific gravity of about 1.6 to 1.9, and the difference in specific gravity with the binder liquid is larger than that of other organic solvents, so that the binder liquid phase and the dispersion solution phase And the phase separation speed at that time increase.
[0023]
More specifically, in the second step, a monomer or oligomer that generates a polymer by polymerization and curing (so-called low molecular binder) is used, or a polymer (plastic polymer) that is cured or solidified by external energy is used, and in the third step, the polymer is used. It is useful to polymerize and cure the monomer or oligomer, or to cure or solidify the polymer.
[0024]
In addition, as a monomer or oligomer, a polymerization curing reaction is caused by heat, moisture (humidity), active energy rays (ionizing radiation such as ultraviolet rays, visible rays, electron beams, other charged particle beams, X rays, and γ rays). Among them, more preferred are monomers or oligomers constituting a photocurable resin or a radiation curable resin, and particularly preferred are monomers or oligomers constituting an ultraviolet curable resin. Furthermore, the polymer that is cured or solidified by external energy is preferably a curable polymer that is cured by light or radiation-sensitive modification or thermal denaturation, and is more preferably a plastic polymer that has ultraviolet curability. In these cases, in the third step, the substrate on which the binder liquid has been applied is preferably irradiated with light or radiation, more preferably with ultraviolet rays.
[0025]
If it carries out like this, the binder liquid itself apply | coated on the base | substrate at the 2nd process or the monomer or oligomer as a binder component contained in it will superpose | polymerize and cure at a 3rd process, and a partition will be formed. Alternatively, the curable polymer is cured or solidified to form the partition walls. Therefore, the liquid liquid and easily applied binder liquid is easily solidified to form a strong partition. In addition, it is more preferable to use a photo-curing or ultraviolet-curing material because non-contact and rapid solidification processing is performed.
[0026]
Alternatively, as the binder liquid in the second step, a polymer that is a binder component (so-called resin binder or polymer binder) is dissolved or mixed in the solvent, and the solvent contained in the binder liquid is removed in the third step. May be. In this case, in the third step, only the solvent is volatilized and removed, so that the binder liquid is solidified very easily and a partition wall made of a polymer is formed.
[0027]
In addition, the present invention is extremely suitable as a method for manufacturing an electrophoretic display device in which a particle body is moved by electrophoresis as a display device.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. Also, the positional relationship such as up / down / left / right is based on the positional relationship of the drawings.
[0029]
FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of a display device obtained by the method for manufacturing a display device according to the present invention, and FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. . The display device 100 is an electrophoretic display device that can be used as electronic paper, and a dispersed solution phase 3 is interposed between a lower electrode layer 2 and an upper electrode layer 6 made of a transparent conductive material formed on a substrate 1. Is provided so as to be covered with the partition walls 4.
[0030]
The dispersion system phase 3 includes migrating particles 10 a and 10 b (particle bodies), which are arranged as a plurality of convex droplets on the lower electrode layer 2, and include the partition wall 4, the substrate 1 and the lower electrode layer 2. Isolated and sealed from each other. The partition 4 is made of a solid polymer, and a space between the partition 4 and the upper electrode layer 6 is embedded with a planarizing layer. Further, an upper protective layer 7 is formed on the entire surface of the upper electrode layer 6.
[0031]
An example of a procedure for manufacturing the display device 100 having such a configuration and a member to be used will be described below. 3A to 3D and FIGS. 4A to 4D are process diagrams showing a state in which the display device 100 is manufactured by the manufacturing method of the present invention.
[0032]
<A. Formation of lower electrode layer>
First, the lower electrode layer 2 is formed on the substrate 1 by a known method such as an RF magnetron sputtering method using a target made of a transparent conductive material (see FIG. 3A).
[0033]
(substrate)
The material of the substrate 1 is not particularly limited, but a flexible transparent resin film having a thickness of 500 μm or less is preferable. Thereby, flexibility can be given to the display device 100, and a wide range of application as electronic paper is possible.
[0034]
(Transparent conductive material)
As the transparent conductive material used for the lower electrode layer 2, In ₂ O _Three , SnO ₂ An oxide conductive material such as ITO (Indium Tin Oxide) or ZnO—Al, a conductive polymer film, or the like can be used. The thickness of the lower electrode layer 2 is usually about 0.05 to 5 μm. In addition, conventionally well-known various methods can be used for the pattern shape, arrangement | positioning, etc. of the lower electrode layer 2. FIG. That is, according to the display pattern, at least one of the lower electrode layer 2 and the upper electrode layer 6 may be patterned, or a TFT circuit for driving may be formed. Further, by providing the lower electrode layer 2 only in the central portion of the pattern, the migrating particles 10a and 10b can be gathered at one central portion.
[0035]
<B. Formation of dispersion system phase 3; first step>
Next, fine particles constituting the migrating particles 10a and 10b are dispersed in an appropriate solvent to prepare a dispersion solution. The dispersion solution is applied by supplying the dispersion solution in the form of droplets (mist) having a constant average particle diameter onto the substrate 1 on which the lower electrode layer 2 is formed, thereby forming a plurality of dispersion solution phases 3 ( (See FIG. 4B).
[0036]
(Dispersion solvent)
Here, the solvent used for the dispersion solution (hereinafter referred to as “dispersion solvent”) is selected from solvents having a sufficiently low compatibility with the binder liquid (described later) for forming the partition walls 4. When a water-soluble polymer (resin) is used as the binder contained, many organic solvents that are hydrophobic solvents can be preferably used. On the other hand, when a binder having lipophilicity, that is, a binder that dissolves in an organic solvent in many cases is used, the solvent that can be used as the dispersion solution is preferably hydrophilic, and the options are narrowed.
[0037]
The dispersion solvent preferably has a higher specific gravity than the binder liquid. In this way, a significant specific gravity difference between the dispersion solution and the binder liquid is generated, and the binder liquid phase and the dispersion solution phase 3 formed when the partition wall 4 is obtained are easily separated from each other. And the binder liquid phase is easily held on the dispersion solution phase 3. In other words, the absolute value of the specific gravity of the dispersion solution solvent is not so important, and the difference in specific gravity between the two affects the phase separation ability. Furthermore, the absolute value of the specific gravity difference between the two is more preferably 0.1 or more, and particularly preferably 0.2 or more. If this specific gravity difference is less than 0.1, the binder liquid phase, the dispersion solution phase 3 and the phase separation speed may be undesirably lowered, and it tends to be difficult to sufficiently separate both. In this case, it is difficult to sufficiently seal the dispersion solution phase 3 with the partition walls 4 when the binder liquid phase is solidified later.
[0038]
Specifically, it is preferable to appropriately select a dispersion solvent that satisfies the above-mentioned preferred requirements from various known solvents. For example, silicone oil (particularly modified silicone oil is preferred, and its modified form is, for example, alcohol. Modification, polyether modification, carboxyl modification, or amino modification.), Aromatic hydrocarbons such as benzene, toluene, xylene, naphthenic hydrocarbons, aliphatic such as hexane, cyclohexane, kerosene, paraffinic hydrocarbons Hydrocarbons, trichloroethylene, tetrachloroethylene, trichlorofluoroethylene, halogenated carbon (hydrocarbon) such as ethyl bromide, solvents with relatively high resistivity such as fluorine-containing ether compounds, fluorine-containing ester compounds, and various other types Oils etc. alone or in appropriate combination of two or more The can be used.
[0039]
Among these, it is more preferable to use a fluorinated solvent as the dispersion solvent. Examples of such fluorinated solvents include perfluorodecane, perfluoro-2,7-dimethyloctane, perfluoro-15-crown-5-ether, perfluorodecalin, perfluoro- (1,2-dimethylcyclohexane). ), Perfluoro (methyldecalin), perfluoroperhydrophenatrene, perfluoro-1,3,5-trimethylcyclohexane, perfluorotripropylamine, perfluorotributylamine, perfluorotripentylamine, 2-trifluoromethyl -3-Ethoxydodecafluorohexane, ethoxynonafluorobutane and the like. However, the fluorine-based solvent is not limited to these.
[0040]
As commercially available fluorine-based solvents, perfluoroalkylamine as a main component manufactured by Sumitomo 3M, Fluorinert FC-40, Fluorinert FC-75, Fluorinert FC-3283, Fluorinert FC-43, etc., and 2- Examples thereof include trifluoromethyl-3-ethoxydodecafluorohexane (HFE7500 manufactured by 3M USA). These can be used by appropriately mixing for the purpose of viscosity adjustment, volatility control and the like. In addition, these fluorine-based solvents are very easy to handle because of their low viscosity and low volatility.
[0041]
Such fluorinated solvents are generally chemically stable and tend to have poor compatibility with many other organic solvents. Therefore, even when an organic substance is used for the binder liquid, the options for the binder liquid can be expanded. In addition, the above-mentioned fluorine-based solvents often have a high specific gravity of about 1.6 to 1.9, and the specific gravity difference from the binder liquid is larger than that of other organic solvents. The mutual separation property with the system solution phase 3 is improved, and the phase separation speed at that time is increased.
[0042]
(Electrophoretic particles)
As the particles used as the electrophoretic particles 10a and 10b, particles generally used in electrophoretic display devices can be used without limitation. For example, titanium oxide, aluminum oxide, carbon black, bitumen, and phthalocyanine green are well known. In addition to the colloidal particles, various organic and inorganic pigments, dyes, metal powders, fine powders such as glass or resin can be used. It is also preferable to use carbon fullerenes and carbon nanotubes, and also carbon fullerene soots and carbon nanotube soots obtained in the production process thereof.
[0043]
Furthermore, among these particle bodies, titanium dioxide, carbon black, carbon fullerene, carbon nanotube, carbon fullerene soot, carbon nanotube soot, and true spherical acrylic particles and true spherical styrene particles formed by combining them are more preferable. . Titanium dioxide and carbon black, carbon black, carbon fullerene, carbon nanotube, carbon fullerene soot, and carbon nanotube soot are the most suitable particulate materials for obtaining white and black, respectively, and are durable and light-resistant. Also excellent. Therefore, the display device 100 that can achieve a stable contrast ratio without fading and discoloration over a long period is realized.
[0044]
Here, when using a substance having a relatively high specific gravity, such as an inorganic pigment or metal powder, as the particle body, it is preferable to combine with a substance having a relatively low specific gravity such as a resin for adjusting the specific gravity. As a composite method, for example, a method of attaching a high specific gravity substance to the resin surface, a method of encapsulating a high specific gravity substance inside the resin, and the like are generally used.
[0045]
The particle size (average particle size) of the particle body is not particularly limited, but is preferably about 0.1 to 10 μm. If the average particle size is less than 0.1 μm, the particles are likely to aggregate, and in this case, the dispersion stability of the migrating particles 10a and 10b in the dispersion solution phase 3 may be undesirably lowered. is there. On the other hand, when the average particle diameter exceeds 10 μm, the flow resistance against the dispersion solvent is excessively increased. This causes a decrease in the responsiveness of the migrating particles 10a and 10b, and the migrating particles 10a and 10b It tends to settle due to its own weight.
[0046]
(Dispersion system droplet formation and coating method)
A specific method for applying the dispersion solution in droplets to the substrate 1 is not particularly limited, and known methods such as a spray nozzle method, an ultrasonic spray method, and an ink jet method can be used. Here, it is preferable to spray so that the average particle diameter of the droplets of the dispersion solution is 10 to 100 μm. If the average particle size is less than 10 μm, the height (swell) of the droplets deposited on the substrate 1 tends to be insufficient, and in this case, a good contrast of the display image may not be obtained. There is. On the other hand, when the average particle diameter exceeds 100 μm, the display quality (resolution) of the display device 100 may be deteriorated.
[0047]
It is known that the shape formed when the droplets of the dispersion solution are deposited on the substrate 1 is different (changes) depending on the interfacial tension between the substrate 1 and the droplets. In other words, the larger the surface tension difference between the droplet application surface of the substrate 1 and the dispersion solution, the more likely the droplets have a convex shape. Therefore, in order to obtain a desired shape of the liquid droplets, it is preferable to subject the substrate 1 on which the lower electrode layer 2 is formed to surface treatment in advance and change the surface tension before applying the dispersion solution.
[0048]
Specifically, the surface tension difference between the surface of the lower electrode layer 2 and the dispersion solution is preferably as large as possible, more preferably 3 mN / m or more, and particularly preferably 5 mN / m or more. If this surface tension difference is less than 3 mN / m, the desired dispersion of the applied dispersion solution tends to be difficult to occur. The upper limit of the surface tension difference is not particularly limited and is preferably as large as possible.
[0049]
Some examples of the surface tension of the dispersion solvent described above are as follows (all units are mN / m).
・ Fluorinert FC-75: 15
・ Fluorinert FC-70: 18
・ Fluorinert FC-40: 16
・ Water: 73
Toluene: 28
・ Ethanol, acetone: 23
・ Silicone oil: 16-21
[0050]
For example, when toluene (surface tension: 28 mN / m) is used as a dispersion solvent, when forming a liquid repellent region on the surface of the substrate 1 on which the lower electrode layer 2 is formed, the surface tension is 25 mN / Preferably, the surface tension is 31 mN / m or more when a lyophilic region is formed.
[0051]
Further, as a surface treatment method for changing the surface tension of the coated surface of the substrate 1, in order to reduce the surface tension to form a water-repellent surface, the surface of the substrate 1 and its -CF in the vicinity _Three It is effective to introduce a fluorine-containing group such as a group, and in some cases, a surface tension of 7 mN / m or less is achieved. Conversely, in order to increase the surface tension to form a hydrophilic surface, it is effective to introduce a hydroxyl group or the like, and for example, a surface tension of 70 mN / m or more is achieved. In addition, the surface tension of the substrate 1 varies depending on the surface state in addition to the material, or more microscopically, morphology. Usually, a surface having moderately fine irregularities is a surface having no such irregularities. It is known that the surface tension increases.
[0052]
<C. Application of binder liquid; second step>
Next, a binder liquid is prepared, and the binder liquid is applied by supplying the binder liquid onto the substrate 1 on which the dispersion solution phase 3 is formed in the form of droplets (mist) having a certain average particle diameter. The applied binder liquid is deposited on the dispersion solution phase 3 as convex binder droplets 4a (see FIG. 4C).
[0053]
The specific method for applying the droplets of the binder liquid onto the substrate 1 is not particularly limited, and is similar to that applied to the dispersion solution described above, such as spray nozzle method, ultrasonic spraying, ink jet method, and the like. These known methods can be used. Here, the binder liquid is preferably supplied onto the substrate so that the average particle diameter of the droplets of the binder liquid is 1/5 or less of the average particle diameter of the droplets of the dispersion solution. Although there is no particular need to limit the lower limit of this ratio, it can be said that about 1/100 is practical. When the value of this ratio exceeds 1/5, the partition wall 4 formed by solidifying the binder liquid in a third step to be described later becomes excessively thick as compared with the dispersion solution phase 3, and in this case, the display device The applied voltage for driving to 100 may increase excessively.
[0054]
Further, the binder liquid preferably has a lower specific gravity than the dispersion solution. As described above, the absolute value of the difference in specific gravity between the two is more preferably 0.1 or more, and particularly preferably 0.2 or more. . However, even when this specific gravity difference is less than 0.1, or even when the binder liquid has a higher specific gravity than the dispersion solution, the interfacial tension with the liquid-repellent or lyophilic region formed on the surface of the substrate 1. Due to the action, it is not impossible to deflect it to the desired position after phase separation. In that case, a desired bending can be realized by performing careful vibration processing for a long time at the time of phase separation.
[0055]
(Binder component)
The binder liquid includes a binder component or the binder component itself. This binder component is an organic substance that constitutes the partition wall 4, and examples thereof include monomers (monomers) and oligomers that are low molecular compounds that form such a polymer by polymerization and curing. Specific examples include those that cause a polymerization and curing reaction with heat, water, or the above-described active energy rays, and monomers and oligomers that constitute an ultraviolet curable resin are particularly preferable.
[0056]
Examples of the monomer or oligomer constituting the active energy ray-curable resin include acrylic acid, methacrylic acid, or ester compounds thereof having an unsaturated double bond that is sensitive to radiation ionization energy and exhibits radical polymerizability ( A group that is cross-linked or polymerized by irradiation such as (meth) acrylic double bond, allylic double bond such as diallyl phthalate, and unsaturated double bond such as maleic acid and maleic acid derivative is contained or introduced in the molecule. The thing etc. can be mentioned. These are preferably polyfunctional, particularly trifunctional or higher, and may be used alone or in combination of two or more.
[0057]
Further, those having a molecular weight of less than 2000 are preferable as the radiation curable monomer, and those having a molecular weight of 2000 to 10,000 are preferable as the radiation curable oligomer. More specifically, examples include styrene, ethyl acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol methacrylate, 1,6-hexane glycol diacrylate, 1,6-hexane glycol dimethacrylate, and the like. Particularly preferable examples include pentaerythritol tetraacrylate (methacrylate), pentaerythritol acrylate (methacrylate), trimethylolpropane triacrylate (methacrylate), trimethylolpropane diacrylate (methacrylate), and an acrylic modified product of urethane elastomer.
[0058]
In addition, examples of radiation curable oligomers include oligoester acrylates and acrylic-modified urethane elastomers, and those in which functional groups such as —COOH groups are introduced.
[0059]
Further, as the binder component, in addition to or instead of these monomers or oligomers, a thermoplastic polymer which is preferably cured or solidified by light or radiation sensitive modification, more preferably radiation functional modification may be used. Specific examples of such radiation curable polymers include acrylic double bonds such as acrylic acid, methacrylic acid, or ester compounds thereof having an unsaturated double bond exhibiting radical polymerizability, such as diallyl phthalate. Examples thereof include thermoplastic polymers having groups capable of crosslinking or polymerizing by irradiation such as allylic double bonds, unsaturated bonds such as maleic acid and maleic acid derivatives.
[0060]
Furthermore, vinyl chloride copolymers, saturated polyester resins, polyvinyl alcohol resins, and polyamide resins are also effective as thermoplastic polymers that can be modified into radiation curable polymers.
[0061]
Since these light or radiation curable monomers or oligomers or light or radiation curable polymers are cured by irradiation with radiation, particularly ultraviolet irradiation, additives such as a photopolymerization initiator or a sensitizer are contained in the binder liquid. It is preferable to contain. Such additives are not particularly limited, and can be appropriately selected from those commonly used such as acetophenone, benzoin, benzophenone, thioxanthone, and the like, and various additives can be used alone or in combination of two or more. It can be used by mixing. Moreover, content of these additives shall be about 0.5 to 5 weight% normally in a binder liquid. The binder liquid as a polymerization composition containing such an additive can be synthesized according to a conventional method, or can be prepared using a commercially available compound.
[0062]
Furthermore, the binder liquid may contain an epoxy resin and a photocationic polymerization catalyst. As an epoxy resin, an alicyclic epoxy resin is preferable and what has two or more epoxy groups in a molecule | numerator is more preferable. Such alicyclic epoxy resins include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis- (3,4-epoxycyclohexylmethyl) adipate, bis- (3,4-epoxycyclohexyl). ) Adipate and the like, and one or more of these are preferably used. Although there is no restriction | limiting in particular in the epoxy equivalent of an alicyclic epoxy resin, From a viewpoint of obtaining favorable sclerosis | hardenability, Preferably it is 60-300, More preferably, it is 100-200.
[0063]
Moreover, a well-known thing can be used for a photocationic polymerization catalyst, and there is no restriction | limiting in particular. For example, one or more metal fluoroborate and boron trifluoride complexes, bis (perfluoroalkylsulfonyl) methane metal salts, aryldiazonium compounds, 6A (16) group aromatic onium salts, 5A (15) group elements It is preferable to use at least one kind of aromatic onium salt, 3A (13) to 5A (15) group dicarbonyl chelate, and thiopyrylium salt.
[0064]
Moreover, you may use organic polymers other than said radiation-curable polymer as a binder component. In this case, a liquid composition obtained by dissolving such a polymer in an appropriate solvent having solubility in the polymer can be used as the polymer liquid. Such a polymer is not particularly limited, and examples thereof include the monomer or oligomer polymers described above.
[0065]
Furthermore, you may add dilution solvents, such as toluene (specific gravity 0.87) and ethylene glycol monoethyl ether acetate (specific gravity 0.975) for adjusting the viscosity and / or specific gravity to a binder liquid. This is effective regardless of whether the binder component is a monomer, an oligomer, or a polymer.
[0066]
Furthermore, you may use a commercial item as a binder liquid, a polymerization initiator, etc. containing such a radiation-curable or radiation-curable binder component. Examples of such commercially available products include acrylic monomers and oligomers and NK esters and NK oligos manufactured by Shin-Nakamura Chemical Co., Ltd., which are introduced into the structure and molecular weight of the main chain constituting the molecule, and the molecule. Various products are available depending on the type and concentration of the functional group.
[0067]
Further, in the case of a structure in which the display is visually recognized through the partition walls 4 which are the binder cured layer, the particle color is observed as it is, and therefore it is desirable that the binder droplet 4a be colorless and transparent after the curing process (solidification process). At least colored and transparent are preferable. However, it is also possible to strengthen the viewer's impression by performing desired coloring. For example, when the migrating particles 10a and 10b have a two-color configuration of white and black, respectively, the display is normally black and white. However, if the dye is colored by adding a red dye to a colorless and transparent binder liquid, a white-red display is obtained. It becomes possible. In addition, when a display is visually recognized from the board | substrate 1 side, it is not necessary to use what has transparency after hardening as a binder liquid.
[0068]
<D. Solidification of binder liquid; third step>
Next, the binder droplet 4a is solidified. When the binder liquid contains light or radiation curable monomer or the like as a binder component, or light or radiation curable polymer, the substrate 1 is irradiated with ultraviolet rays V or the like from the side where the binder droplet 4a is applied. Then, the binder droplet 4a is polymerized and cured to obtain a solidified binder 4b (see FIG. 3D). In the case where the binder solution contains a diluting solvent, after the phase separation, the diluting solvent is volatilized and removed by heat treatment or the like and then irradiated with ultraviolet rays V or the like to carry out polymerization and curing.
[0069]
Further, when the binder liquid is formed by dissolving a polymer other than the radiation-curable polymer as a binder component in a solvent, the binder droplet 4a is removed by volatilizing and removing the solvent by heat treatment or the like after the phase separation. Solidify. In this case, even if the binder liquid contains a diluting solvent, it can be volatilized and removed at the same time.
[0070]
<E. Re-application and re-solidification treatment of binder liquid; second step and third step, respectively. The partition wall 4 may be formed by performing the above-described binder liquid application and solidification treatment only once. From the viewpoint of reducing the drive voltage of the display device 100 as much as possible by reducing the thickness, it is advantageous to perform a series of binder liquid application and solidification processes in a plurality of times. That is, it is possible to prevent uneven distribution of the binder droplets 4a due to surface tension when the coating is performed in a plurality of times. 4A and 4B show a state in which such recoating and re-solidification processes are performed, and solidifying binders 4b and 4c are further laminated to form the partition walls 4. Although the number of such repeated treatments varies depending on the thickness required for the partition 4 and the droplet size of the binder liquid, it is preferable to divide it into several times to about 10 times, for example.
[0071]
The hardness of the partition wall 4 made of the polymer formed by hardening or solidifying the binder component as described above varies depending on the molecular structure of the polymer, particularly the main chain structure. For example, those having a urethane bone core generally exhibit flexibility. There are many. Furthermore, when a flexible display device 100 is manufactured as the display device 100, it is preferable to use a binder component that makes the partition wall 4 have a pencil hardness that is softer than HB.
[0072]
Among them, as the binder component, the above-described radiation curable monomer or oligomer or ultraviolet curable polymer having an acrylic group or an acrylic skeleton, and a binder liquid containing a photopolymerization sensitizer or an initiator is used as a radiation. Those obtained by ultraviolet curing are preferred.
[0073]
<F. Flattening process>
Further, when the partition wall 4 is as thin as shown in FIG. 1, the surface of the partition wall 4 may have minute unevenness that is unavoidable due to the thin coating thickness of the binder droplets. In this case, when the upper electrode layer 6 is directly formed thereon, an unnecessary electric field distribution may be generated and the migrating particles 10a and 10b may not be moved quickly. Therefore, in such a case, it is preferable to provide the planarization layer 5 over the partition 4 in order to eliminate such inconvenience (see FIG. 4C). The planarizing layer 5 may be formed of the same polymer as the partition walls 4 or may be formed of a different polymer, and a thermoplastic polymer or the like can also be used.
[0074]
As a specific method for forming the flattening layer 5, for example, a monomer composition containing an ultraviolet curable monomer or the like, or a resin composition in which a polymer is dissolved, the partition 4 is formed in a liquid or liquid droplet form. The method of superposing | polymerizing hardening or solidifying after apply | coating on the formed board | substrate 1 is mentioned. At this time, since the purpose is flattening, after applying the composition, it takes an appropriate time and waits for the entire layer to be leveled by using the leveling effect of the liquid, followed by polymerization hardening or solidification treatment. It is desirable to do.
[0075]
<G. Formation of upper electrode layer, etc.>
Then, a known conductive material (for example, when the upper electrode layer 6 is a non-translucent layer, copper, aluminum, carbon fine particles, etc., when the translucent layer is used, the same as the lower electrode layer 2 is used. The upper electrode layer 6 is formed on the planarization layer 5 using a material) and a method. Specifically, a film made of a conductive material may be formed on the planarizing layer 5, or a substrate on which a conductive film is formed in advance is used as an upper substrate (corresponding to the upper protective layer 7). The flattening layer 5 may be tightly fixed. In this case, you may perform the hardening process of the monomer composition which comprises the planarization layer 5 in the state which mounted this upper board | substrate on the uncured planarization layer 5. FIG. Thereafter, if necessary, an upper protective layer 7 is formed, electrodes are further attached to the lower electrode layer 2 and the upper electrode layer 6, and a drive circuit and a power source are further connected to obtain the display device 100.
[0076]
According to such a method for manufacturing a display device of the present invention, after a plurality of dispersion solution phases 3 are deposited by applying droplets of a dispersion solution containing migrating particles 10a and 10b on a substrate 1, The binder liquid is also applied in the form of droplets to cover the dispersion solution phase 3, and the binder droplets 4a to 4c are solidified in that state. The partition 4 thus formed securely seals the dispersion solution phase 3 while individually separating the dispersion solution phase 3, so that mixing and dissipation of the dispersion solution and the migrating particles 10a and 10b are prevented, and sufficient contrast is obtained. Display device 100 can be configured.
[0077]
In addition, the manufacturing procedure eliminates the complicated and difficult and time-consuming steps of enclosing the dispersion solution in the microcapsule and forming cells and indentations for enclosing the dispersion solution. can do. Therefore, the throughput in manufacturing the display device 100 can be improved, and thereby the manufacturing cost can be reduced and the economic efficiency can be significantly improved.
[0078]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the upper protective layer 7 and / or the planarizing layer 5 may be omitted. In addition to the electrophoretic display device, the display device 100 charges the electrophoretic particles 10a and 10b by applying an electric field to the electrophoretic particles 10a and 10b using an external device (electric field application head, electrostatic ion flow device, etc.). It can also be set as the display apparatus which controls and displays the distribution state of 10a, 10b. Furthermore, the display device 100 may be a magnetophoretic display device that performs display by applying a magnetic field from the outside to control the distribution state of the migrating particles.
[0079]
Furthermore, it is also possible to use a mixture of a plurality of types of solvents that are not compatible with each other as a solvent (dispersion solvent) for the dispersion solution. As the binder liquid used at this time, a liquid insoluble in these plural kinds of solvents is selected and used. For example, when a mixed solvent of a fluorinated solvent and an organic solvent is used as the dispersion solvent, an aqueous binder liquid is used. Furthermore, when two kinds of electrophoretic particles 10a and 10b having different colors are used, one is subjected to a fluorinated solvent surface treatment and dispersed in a fluorinated solvent, and the other is subjected to a philic organic solvent surface treatment to form an organic solvent. It is preferable to be dispersed.
[0080]
In addition, it is also preferable to perform a defoaming process under reduced pressure before performing the solidification process (curing process) of the binder droplets 4a to 4c. Moreover, when performing the hydrofluorination process of the board | substrate 1, it is preferable to introduce | transduce a hydroxyl group etc. over the whole surface of the board | substrate 1, and to perform a hydrophilic treatment before that. By doing so, the fluoride group is bonded to the hydrophilic functional group to form a stronger fluorinated surface. For this purpose, it is possible to apply known methods such as heating in an oxygen atmosphere, ultraviolet irradiation, plasma CVD, and surface modification by corona discharge treatment. In addition, when the hydrophilization treatment is performed, the region that has not been subjected to the hydrofluorination treatment develops strong hydrophilicity, so that the liquid repellency of the dispersion solution using an organic solvent as the dispersion solvent is enhanced, and the dispersion solvent is unevenly distributed. Can be further promoted.
[0081]
Hereinafter, the content of the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
[0082]
<Examples 1-8>
A 100 μm-thick polyethylene terephthalate film was prepared as the substrate 1. First, an ITO transparent conductive film was formed on the substrate 1 by sputtering, and then a heat treatment was performed in the atmosphere at 80 ° C. for 1 hour to form the lower electrode layer 2. Further, a fluorine-based silazane oligomer (manufactured by Shin-Etsu Chemical Co., Ltd .: KP-801M) was applied to the surface of the lower electrode layer 2 by spray coating, and then allowed to stand at 80 ° C. for 1 hour.
[0083]
On the other hand, as the migrating particles 10a and 10b, spherical acrylic particles (black colored particles) having an average particle diameter of 1 μm having carboxy groups on the surface and spherical acrylic particles having an average particle diameter of 3.5 μm (titanium oxide fixed on the surface) ( White particles) were subjected to a surface treatment using a fluorine-based silazane oligomer (manufactured by Shin-Etsu Chemical Co., Ltd .: KP-801M) as a fluorine-based surface treatment agent. 8 parts of the black particles, 3 parts of white particles, 3 parts of fluoropolyether (Daikin Industries: demnum S-20) as a solvent additive and 95 parts of Fluorinert FC-40 (manufactured by Sumitomo 3M) as a fluorinated solvent; 15 parts of HFE7500 (manufactured by 3M) was mixed by ultrasonic dispersion to prepare a dispersion solution.
[0084]
Next, the dispersion solution was formed into droplets having various average particle diameters using an ink jet nozzle and applied to the surface of the lower electrode layer 2 on the substrate 1. When the surface state was observed with a microscope, when the droplet diameter was 50 μm, there was a pattern in which a large number of droplets of a dispersion solution having a substantially circular cross-section with a diameter of about 70 to 100 μm were present in an isolated state at random. It was confirmed that it was formed. In addition, the location which adjacent droplets contacted and formed one big pattern was also recognized.
[0085]
Furthermore, a polymerizable composition having the following composition was prepared as a binder liquid.
Oligoester acrylate (molecular weight 5,000): 50 parts by weight
Trimethylolpropane triacrylate: 50 parts by weight
・ Acetophenone photopolymerization initiator: 3 parts by weight
[0086]
This binder liquid was made into droplets having various average particle diameters by a spray nozzle and applied onto the substrate 1 on which the dispersion solution was applied. Then, the binder liquid was cured by irradiating with ultraviolet V using a high-pressure mercury lamp. Thereafter, a dispersion solution of droplets having the same average particle diameter as described above was applied, and the ultraviolet curing treatment was repeated three times to form the partition walls 4. Further, a flattened layer 5 was formed by spray-coating a binder liquid having an average particle diameter of 50 μm and curing the binder liquid.
[0087]
Next, a carbon paste-containing conductive polymer was applied to the surface to form an upper electrode layer 6, and an upper protective layer 7 made of a 100 μm polyethylene terephthalate film was attached. Finally, conductive wires were attached to the lower electrode layer 2 and the upper electrode layer 6 and connected to an external voltage application device to complete various display devices. The specific gravity of the dispersion solution was 1.85, the specific gravity of the binder liquid was 1.25, and the specific gravity difference was 0.6.
[0088]
<Characteristic evaluation>
A voltage of ± 10 V was applied to each display device obtained in Examples 1 to 8 to change it to black and white, and the brightness in the range of 0.2 mmφ was measured at 100 locations with a microscope, and the maximum and minimum values of the contrast were measured. The average value was calculated. Note that the area of 0.2 mmφ as the luminance measurement range is a size that generally feels rough when the display surface has a variation in contrast and when the display surface is visually observed. The obtained results are shown in Table 1 together with the average droplet size of the dispersion solution, the average particle size of the binder droplets, and the particle size ratio thereof.
[0089]
[Table 1]

[0090]
From these results, the display device obtained in each example has an average contrast of 2 or more, and in particular, the display devices of Examples 1 to 4 achieve a contrast of approximately 10 or more. It was confirmed that it was superior to 5-8. The display device obtained in Example 1 showed a value of 10 or more at 90% or more of the luminance measurement points. Further, when the black-and-white reversal display was performed 10,000 times with the display surface set vertically, the display on the entire screen was uniform and no display unevenness was observed.
[0091]
【The invention's effect】
As described above, according to the method for manufacturing a display device of the present invention, it is possible to obtain a display device that can improve the economy by simplifying the manufacturing process while ensuring sufficient visibility.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of a display device obtained by a method for manufacturing a display device according to the present invention.
FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG.
3A to 3D are process diagrams showing a state in which the display device 100 is manufactured by the manufacturing method of the present invention.
4A to 4D are process diagrams showing a state in which the display device 100 is manufactured by the manufacturing method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Lower electrode layer, 3 ... Dispersed solution phase, 4a ... Binder droplet, 4b, 4c ... Solidified binder, 4 ... Partition, 5 ... Flattening layer, 6 ... Upper electrode layer, 7 ... Upper protection Layers, 10a, 10b ... migrating particles (particles), 100 ... display device, V ... ultraviolet rays.

Claims (9)

A method of manufacturing a display device in which display is performed by a change in a spatial distribution state of a plurality of particles in a dispersion solution in which a plurality of particles is dispersed in a solvent,
A first step of supplying the dispersion solution in a droplet state onto a substrate;
A second step of supplying, in a droplet state, a binder liquid containing a binder component and insoluble in the solvent on the substrate on which the dispersion solution is applied;
A third step of solidifying the binder component in the binder liquid applied on the substrate, or the binder liquid itself;
A method for manufacturing a display device, comprising: In the first step, the dispersion solution is supplied onto the substrate so that the average particle size of the droplets of the dispersion solution is 10 to 100 μm.
The method of manufacturing a display device according to claim 1. In the second step, a binder having a specific gravity lower than that of the dispersion solution is used as the binder liquid.
The method of manufacturing a display device according to claim 1 or 2. In the second step, the binder liquid is supplied onto the substrate such that the average particle diameter of the droplets of the binder liquid is 1/5 or less of the average particle diameter of the droplets of the dispersion solution.
The manufacturing method of the display apparatus as described in any one of Claims 1-3 characterized by the above-mentioned. The second step and the third step are repeated a plurality of times in that order.
The manufacturing method of the display apparatus as described in any one of Claims 1-4 characterized by the above-mentioned. In the first step, a fluorinated solvent is used as the solvent contained in the dispersion solution.
The manufacturing method of the display apparatus as described in any one of Claims 1-5 characterized by the above-mentioned. In the second step, an ultraviolet curable monomer, an ultraviolet curable oligomer, or an ultraviolet curable polymer is used as the binder component or the binder liquid.
In the third step, light or radiation is irradiated onto the substrate on which the binder liquid has been applied.
The manufacturing method of the display apparatus as described in any one of Claims 1-6 characterized by the above-mentioned. In the second step, the binder liquid is prepared by dissolving or mixing the polymer as the binder component in a solvent,
The method for manufacturing a display device according to claim 1, wherein in the third step, the solvent contained in the binder liquid is removed. As the display device, an electrophoretic display device provided so that the particle body moves by electrophoresis is manufactured.
The manufacturing method of the display apparatus as described in any one of Claims 1-7 characterized by the above-mentioned.

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