JP2013057875A - Coating film formed on electrode surface of electrophoretic display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating film formed on a surface of an electrode of an electrophoretic display device, capable of improving a driving property and a memory property of charged particles and uniformly formed on the surface of the electrode.SOLUTION: A coating film of the embodiment is formed on a surface of an electrode provided for an electrophoretic display device. The electrode of the electrophoretic display device is for moving charged particles dispersed in an insulation fluid by an electric field. The coating film is a molecular film including a molecule having: at least one active functional group selected from a thiol group, a disulfide group, a hydrosilyl group and a hydrolyzable silyl group; and a hydrophobic functional group.

Description

  The present invention relates to a coating film formed on the surface of an electrode of an electrophoretic display device.

  In an electrophoretic display device having an electrode for moving charged particles dispersed in an insulating fluid by an electric field, the characteristics of the electrophoretic display device are improved by covering the surface of the charged particles and the electrode with a fluororesin. Is known (see, for example, Patent Documents 1 and 2).

  Further, it is known that when the electrode surface is covered with a polyimide resin having an alkyl side chain, adsorption of charged particles to the electrode can be prevented (see, for example, Patent Document 3).

Japanese Patent Publication No. 61-25139 Japanese Patent No. 2729299 Japanese Patent No. 4284220

  However, since the wettability of the fluorine-based resin to the electrode is low, it is difficult to uniformly apply the fluorine-based resin film on the surface of the electrode.

  In addition, when an insulating resin film such as a polyimide resin film is formed on the surface of the electrode, the charged particles are neutralized even if the electric field is released after the charged particles are moved to the surface of the resin film on the electrode by an electric field. hard. Therefore, charged particles having the same charge repel each other and do not stay on the surface of the resin film, so that the memory property of the charged particles is deteriorated.

  In addition, unless a coating film is formed on the surface of the electrode, the charged particles stick to the surface of the electrode. For this reason, even if positive and negative voltages are alternately applied to the electrodes, the charged particles are difficult to drive, and the drivability of the charged particles is reduced.

  The present invention has been made in view of the above circumstances, and is a coating film formed on the surface of an electrode of an electrophoretic display device, which can enhance the driveability and memory property of charged particles, It aims at providing the coating film formed uniformly on the surface of the electrode.

  In order to solve the above-described problem, a coating film according to one aspect of the present invention is provided on the surface of the electrode of an electrophoretic display device including an electrode for moving charged particles dispersed in an insulating fluid by an electric field. A molecule comprising a molecule having at least one active functional group among a thiol group, a disulfide group, a hydrosilyl group, and a hydrolyzable silyl group, and a hydrophobic functional group. It is a membrane.

  In the coating film of this invention, since a molecule | numerator has a hydrophobic functional group, it is suppressed that a charged particle adheres to the coating film in the surface of an electrode. As a result, the drivability of charged particles can be improved. Moreover, since the active functional group is chemically bonded to the surface of the electrode, the wettability with respect to the surface of the electrode is increased. For this reason, a coating film can be uniformly formed in the surface direction of the surface of an electrode. Further, when the electric field is released after the charged particles move to the surface of the electrode due to the electric field, the charged particles are sufficiently discharged because the coating film is a molecular film that does not exhibit insulation. Therefore, since repulsion between charged particles having the same charge can be suppressed, the charged particles are prevented from being detached from the surface of the electrode. Therefore, the memory property of the charged particles can be improved.

  Therefore, according to the present invention, the driveability and memory property of charged particles can be improved, and a coating film formed uniformly on the surface of the electrode can be obtained.

  The hydrophobic functional group may be an alkyl group or a silicon-containing group. The molecule may be an alkanethiol. The molecule may be a Si-H bond-containing polysiloxane. The molecule may be a silane coupling agent. The electrode may be made of a material containing at least one of gold and ITO.

  The coating film which concerns on another one side of this invention is a coating film formed on the surface of the said electrode of the electrophoretic display apparatus provided with the electrode for moving the charged particle disperse | distributed in the insulating fluid with an electric field And the said coating film is a molecular film containing the molecule | numerator which has an active functional group chemically bonded with the said surface of the said electrode, and a hydrophobic functional group.

  An electrophoretic display device according to another aspect of the present invention includes an electrode for moving charged particles dispersed in an insulating fluid by an electric field, and a coating film formed on the surface of the electrode. The coating film is a molecular film containing a molecule having at least one active functional group and a hydrophobic functional group among a thiol group, a disulfide group, a hydrosilyl group, and a hydrolyzable silyl group.

  A method of forming a coating film according to another aspect of the present invention is formed on the surface of an electrode of an electrophoretic display device including an electrode for moving charged particles dispersed in an insulating fluid by an electric field. A method of forming a coating film comprising the step of forming a coating film on the surface of the electrode, wherein the coating film has at least one activity among a thiol group, a disulfide group, a hydrosilyl group, and a hydrolyzable silyl group. It is a molecular film containing a molecule having a functional group and a hydrophobic functional group.

  A composition according to another aspect of the present invention is a coating film formed on the surface of an electrode of an electrophoretic display device including an electrode for moving charged particles dispersed in an insulating fluid by an electric field. The composition includes a molecule having at least one active functional group among a thiol group, a disulfide group, a hydrosilyl group, and a hydrolyzable silyl group, and a hydrophobic functional group.

  According to the present invention, a coating film formed on the surface of an electrode of an electrophoretic display device, which can improve the driveability and memory property of charged particles and is uniformly formed on the surface of the electrode. A membrane is provided.

It is sectional drawing which shows typically an example of the electrophoretic display device provided with the electrode in which the coating film which concerns on one Embodiment was formed on the surface. FIG. 6 is a process cross-sectional view illustrating an example of a manufacturing method of the electrophoretic display device in FIG. 1. It is sectional drawing which shows typically another example of the electrophoretic display device provided with the electrode in which the coating film which concerns on one Embodiment was formed on the surface.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate descriptions are omitted.

(Electrophoretic display device)
FIG. 1 is a cross-sectional view schematically illustrating an example of an electrophoretic display device including an electrode having a coating film formed on a surface according to an embodiment. The electrophoretic display device 10 shown in FIG. 1 is, for example, electronic paper. The electrophoretic display device 10 includes a first electrode 5a and a second electrode 5b for moving the charged particles 1 dispersed in the insulating fluid 2 by an electric field.

  For example, the first electrode 5a is provided on the colored resin layer 4 provided on the substrate 3a. The 2nd electrode 5b is provided so that the upper surface and side surface of the partition 7 arrange | positioned through the insulating colored resin layer 6 on the board | substrate 3a may be covered, for example. The thickness of the first electrode 5a and the second electrode 5b is, for example, about 20 nm. A region between adjacent partition walls 7 corresponds to each pixel of the electrophoretic display device 10. The partition walls 7 are arranged, for example, in a lattice shape on the main surface of the substrate 3a. A substrate 3 b is disposed on the upper surface of the partition wall 7 with an adhesive layer 9 interposed therebetween. The substrate 3b is disposed to face the substrate 3a. A coating film 8 is formed on the surfaces of the first electrode 5a and the second electrode 5b. The charged particles 1 and the insulating fluid 2 are accommodated in a space surrounded by the substrate 3a, the substrate 3b, and the partition wall 7.

  FIG. 1A shows the electrophoretic display device 10 when a negative voltage is applied to the first electrode 5a and a positive voltage is applied to the second electrode 5b. In this case, the charged particles 1 are attracted to the surface of the first electrode 5a. FIG. 1B shows the electrophoretic display device 10 when a positive voltage is applied to the first electrode 5a and a negative voltage is applied to the second electrode 5b. In this case, the charged particles 1 are attracted to the surface of the second electrode 5b.

  The charged particles 1 may be any of inorganic particles made of carbon black, silica, etc., organic particles made of a polymer resin such as polystyrene, or composite particles thereof. The average particle size of the charged particles 1 is preferably 0.1 to 8 μm. When the average particle size is 0.1 μm or more, the production of the particles becomes easy. When the average particle size is 8 μm or less, the resolution required when electronic paper is used can be easily obtained. The average particle size is determined by the particle size distribution measuring device (the average particle size range of 0.1 μm to 1 μm is “Zeter Sizer Nano Series (ZS)” manufactured by Malvern, and the average particle size range of 1 μm to 8 μm is “Multi” manufactured by Beckman Coulter. The size of the charged particles 1 is preferably spherical (the surface is uniform). In this case, since the surface charge of the charged particles 1 is constant, all the charged particles 1 are The charged particles 1 are preferably colored as necessary, and particularly preferably black, and the colorant for coloring the charged particles 1 is not particularly limited. And pigments or dyes such as carbon black, titanium oxide, etc. The kind and color of the dye compound are not limited, and two or more dye compounds may be used. In view of handling, it is preferable that it is soluble in an aqueous solvent.The types of dyes can be exemplified as follows: azo dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoneimine dyes , Cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, naphthalimide dyes, azine dyes, phthalocyanine dyes, triphenylmethane dyes. , “Valifast Red”, “Valifast Black” (manufactured by Orient Chemical Co., Ltd.).

  The insulating fluid 2 is not particularly limited, but is preferably a liquid made of an insulating organic compound. Examples of the insulating organic compound include aliphatic hydrocarbons, aromatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, aliphatic esters, aromatic esters, aliphatic alcohols, aromatic alcohols, fats and oils, and the like. The Preferably, isoparaffinic aliphatic hydrocarbons and aromatic hydrocarbons are used.

  As the substrate 3a and the substrate 3b, films made of polymers such as polyethylene terephthalate (PET), polyimide (PI), polycarbonate (PC), polyethersulfone (PES), polyethylene naphthalate (PEN), glass, quartz, etc. Substrates made of inorganic materials can be used. As a constituent material of the substrate 3a and the substrate 3b, it is preferable to use a transparent material having a high light transmittance. Further, a hydrophobic resin may be coated on the outermost surface of the substrate 3b in order to prevent the charged particles 1 from adhering. Examples of the hydrophobic resin include silicone resins, poly (meth) acrylate resins containing alkyl groups, and fluorine-containing resins.

  The colored resin layer 4 is not particularly limited, but is preferably white. For example, white pigments such as titanium oxide, zinc oxide, white lead, and lithopone can be added to poly (meth) acrylate resin, polyester resin, polycarbonate resin, polyarylate resin, novolac resin, epoxy resin and the like to whiten.

  The first electrode 5a and the second electrode 5b are not particularly limited as long as they are conductive materials, but are preferably made of a material containing at least one of gold and ITO (indium tin oxide). The first electrode 5a and the second electrode 5b are made of, for example, gold, silver, copper, platinum, palladium, ITO, aluminum, or the like.

  The insulating colored resin layer 6 is not particularly limited, but is preferably the same color as the charged particles 1 and more preferably black. For example, a black pigment such as carbon black, titanium black, black iron oxide or the like can be added to a poly (meth) acrylate resin, a polyester resin, a polycarbonate resin, a polyarylate resin, a novolac resin, an epoxy resin, or the like for blackening.

  The partition wall 7 is preferably made of a polymer resin. Examples of the polymer resin include poly (meth) acrylate resin, polyester resin, polycarbonate resin, polyarylate resin, novolac resin, and epoxy resin. In addition, it is preferable that the partition 7 consists of photosensitive resin from the ease of pattern formation. Specific examples of the material include a photosensitive epoxy resin (trade name: SU-8, manufactured by Nippon Kayaku Co., Ltd.).

  The coating film 8 is a molecular film containing molecules having an active functional group and a hydrophobic functional group. The active functional group is at least one of a thiol group (—SH), a disulfide group (—SS—), a hydrosilyl group (Si—H group), and a hydrolyzable silyl group. Examples of the hydrolyzable silyl group include an alkoxysilyl group, a hydroxysilyl group, a halogenated silyl group, an acetoxysilyl group, and an aminoxysilyl group. The hydrophobic functional group may be an alkyl group or a silicon-containing group. The molecule contained in the coating film 8 has, for example, an active functional group at one end and a hydrophobic functional group at the other end. The coating film 8 is, for example, a monomolecular film, but may be a multimolecular film.

The molecule contained in the coating film 8 may be an alkanethiol. Examples of the alkanethiol include a linear alkanethiol represented by CH ₃ — (CH ₂ ) _n-1- SH. n is preferably an integer of 1 to 24, and particularly preferably 3 to 22. The carbon chain of alkanethiol may have one or two or more branched chains, but a straight chain is preferably used. Moreover, alkanethiol may have 1 or 2 or more substituents. Examples of the substituent include alkenyl, alkynyl, aryl, carboxyl, amino, hydroxyl, alkoxy, ester, nitrile, amide, mercapto, halogeno, ferrocenyl, hydroquinone, pyridyl. Group, parahydroxyphenyl group and the like. The kind and number of such substituents are not particularly limited. The type and number of substituents are preferably selected so as not to inhibit the formation of a self-assembled molecular film (SAM) and to increase the defects of the film.

The molecule contained in the coating film 8 may be Si-H bond-containing polysiloxane (silicon-hydrogen bond-containing polysiloxane). Examples of the Si—H bond-containing polysiloxane include Si—H bond-containing polysiloxane represented by the following formula.

  In the formula, X is preferably an integer of 1 to 300, and Y is preferably an integer of 1 to 300. Specific product names include SH1107 manufactured by Toray Dow Corning, XL91A, XL12031, XL97A, and XL96A manufactured by Arakawa Chemical Industries.

The molecule contained in the coating film 8 may be a silane coupling agent. Silane coupling agents include CH _3- (CH ₂ ) _n-1- Si (OR) ₃ , CH _3- (CH ₂ ) _n-1- Si (CH ₃ ) (OR) ₂ , CH _3- (CH ₂ ) _n-1 —Si (CH ₃ ) ₂ (OR) silicone compound (—SiOR group), CH ₃ — (CH ₂ ) _n−1 —SiCl ₃ , CH ₃ — (CH ₂ ) _{n— 1} -Si (CH ₃₎ Cl ₂ or _{CH 3 - (CH 2) n} -1 -Si (CH 3) a silicone compound represented by ₂ Cl (-SiX group .X is a halogen element) are exemplified. n is preferably an integer of 1 to 24, and particularly preferably 3 to 22. R is, for example, CH ₃ , C ₂ H ₅ , COCH ₃ .

  Examples of the silane coupling agent include compounds having an alkoxysilyl group at one end and a mercapto group at the other end (alkoxysilane having a mercapto group). Specific examples of such a compound include 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and the like.

  Examples of the silane coupling agent include compounds having an alkoxysilyl group at one end and an isocyanate group at the other end (alkoxysilane having an isocyanate group). Specific examples of such a compound include 3-isocyanatopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane.

  The thickness of the coating film 8 is, for example, 1 to 50 nm. The resistance value R1 measured by applying a tester to the surface of the coating film 8 is preferably 100 MΩ or less. The resistance value R1 satisfies the formula (R2 × 0.9 ≦ R1 ≦ R2 × 100) when the resistance value R2 measured by applying a tester to the surfaces of the first electrode 5a and the second electrode 5b is used. preferable. Moreover, it is preferable that the contact angle of the surface of the coating film 8 and water is larger than the contact angle of the surface of the 1st electrode 5a and the 2nd electrode 5b, and water.

  In the electrophoretic display device 10, an electric field is formed between the first electrode 5a and the second electrode 5b by applying a voltage to the first electrode 5a and the second electrode 5b. Due to this electric field, the charged particles 1 move to the surface of the first electrode 5a or the surface of the second electrode 5b. Further, by reversing the direction of the electric field, the charged particles 1 can be driven between the first electrode 5a and the second electrode 5b. Further, when the voltage applied to the first electrode 5a and the second electrode 5b is stopped and the electric field is released, the charged particles 1 remain in place.

  Here, the electrophoretic display device 10 includes a coating film 8. Since the molecules of the coating film 8 have a hydrophobic functional group, the charged particles 1 are prevented from sticking to the first electrode 5a or the second electrode 5b. As a result, the drivability of the charged particles 1 can be improved. Moreover, the molecule | numerator of the coating film 8 has an active functional group. Since the active functional group chemically bonds with the surface of the first electrode 5a or the second electrode 5b, the wettability with respect to the surface of the first electrode 5a or the second electrode 5b is increased. For this reason, the coating film 8 can be uniformly formed on the surface of the first electrode 5a or the second electrode 5b. Further, when the electric field is released after the charged particles 1 move to the surface of the first electrode 5a or the second electrode 5b by the electric field, the charged particles 1 are sufficiently discharged because the coating film 8 is a molecular film that does not exhibit insulation. Is done. Therefore, since repulsion between the charged particles 1 having the same charge can be suppressed, the charged particles 1 are prevented from being detached from the surface of the first electrode 5a or the second electrode 5b. Therefore, the memory property of the charged particles 1 can be improved.

  Therefore, in this embodiment, the driveability and memory property of the charged particles 1 can be improved, and the coating film 8 formed uniformly on the surface of the first electrode 5a or the second electrode 5b can be obtained.

(Method for manufacturing electrophoretic display device)
FIG. 2 is a process cross-sectional view illustrating an example of a manufacturing method of the electrophoretic display device of FIG. For example, the electrophoretic display device 10 is manufactured through the following steps.

  First, as shown in FIG. 2A, a first electrode 5a provided on the substrate 3a and a second electrode 5b provided so as to cover the side surface of the partition wall 7 arranged on the substrate 3a. Prepare the provided structure. A colored resin layer 4 is disposed between the substrate 3a and the first electrode 5a. An insulating colored resin layer 6 is disposed between the substrate 3 a and the partition wall 7.

  Next, as shown in FIG. 2B, a coating film 8 is formed on the surfaces of the first electrode 5a and the second electrode 5b. Specifically, molecules having at least one active functional group among thiol group, disulfide group, hydrosilyl group and hydrolyzable silyl group and a hydrophobic functional group are placed on the surfaces of the first electrode 5a and the second electrode 5b. Apply to. Thereby, the said molecule | numerator and the surface of the 1st electrode 5a and the 2nd electrode 5b react and chemically bond. The reaction temperature and reaction time are not particularly limited. For example, the reaction time when the reaction is performed at room temperature (22 ° C.) is preferably about several seconds to several tens of hours, and more preferably 1 hour to 18 hours. When the reaction time is several seconds or more, an ordered molecular film is easily formed. When the reaction time is set to several tens of hours or less, the risk of film breakage can be reduced.

  In addition, you may dilute the molecule | numerator which has an active functional group and a hydrophobic functional group with the organic solvent, and it may apply | coat on the surface of the 1st electrode 5a and the 2nd electrode 5b. Examples of the organic solvent include, but are not limited to, alcohols such as methanol, ethanol, and isopropanol, aromatic hydrocarbons such as benzene, toluene, and xylene, and aliphatic hydrocarbons such as n-hexane, n-pentane, and isooctane. And N, N-dimethylformamide can be used. The organic solvent is appropriately selected according to the constituent materials, reaction temperature, etc. of the first electrode 5a and the second electrode 5b while referring to a paper (Yamada, R. et al., Chem. Lett., 667, 1999). It is preferable.

  Next, as shown in FIG. 2C, an adhesive layer 9 is formed on the upper surface of the partition wall 7, and the dispersion liquid containing the insulating fluid 2 and the charged particles 1 dispersed in the insulating fluid 2 is separated from the partition wall. Fill between 7. Thereafter, the electrophoretic display device 10 shown in FIG. 1 is obtained by attaching the substrate 3b to the adhesive layer 9 and performing sealing.

  As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment. For example, the coating film 8 may be formed on at least one surface of the first electrode 5a and the second electrode 5b. The electrophoretic display device 10 may include a third electrode in addition to the first electrode 5a and the second electrode 5b.

  The driving method of the electrophoretic display device 10 shown in FIG. 1 is an In-Plane method, but is not limited thereto. For example, FIG. 3 is a cross-sectional view schematically illustrating another example of an electrophoretic display device including an electrode on which a coating film according to an embodiment is formed. As shown in FIG. 3, a first electrode 5a and a second electrode 5b may be formed on a pair of opposing substrates 3a and 3b, respectively. In this case, the charged particles can move along the observation direction (the normal direction of the substrates 3a and 3b). For example, in the electrophoretic display device 20 shown in FIG. 3A, the black charged particles 1 have a positive charge, and the white charged particles 1a have a negative charge. In the electrophoretic display device 30 shown in FIG. 3B, the black charged particles 1 have a positive charge, and the red charged particles 1b have a negative charge. In the electrophoretic display device 40 shown in FIG. 3C, the black charged particles 1 have a positive charge, and the green charged particles 1c have a negative charge. In the electrophoretic display device 50 shown in FIG. 3D, the black charged particles 1 have a positive charge, and the blue charged particles 1d have a negative charge.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
A 2000 ml separable flask equipped with a stirrer, condenser, thermometer and gas inlet tube was charged with 157 g of styrene, 157 g of γ-methacryloxypropyltrimethoxysilane, 79 g of polyvinylpyrrolidone, 1170 g of methanol and 41 g of water, and under nitrogen flow. The temperature was raised to 62 ° C. Thereafter, 12 g of 4,4′-azobis (2-methylbutyronitrile) was added and subjected to precipitation polymerization for 6 hours to obtain a slurry A containing crosslinkable polymer particles having hydrolyzable silyl groups.

  10 g of dye having amino group in the molecule (manufactured by Orient Chemical Co., Ltd., VALIFASTBLACK3810), 4 g of 3-isocyanatopropyltriethoxysilane and 100 g of methyl ethyl ketone were charged into a 200 ml flask, heated to 50 ° C. and held for 1 hour. After cooling. Next, 4 g of methanol was added and evaporated to obtain a reaction solution B containing a dye compound having a hydrolyzable silyl group.

  50 g of the reaction solution B was added to 100 g of the methanol dispersion liquid from which the unreacted polymerizable vinyl monomer present in the slurry A was removed, and the mixture was heated to 60 ° C. Subsequently, 11.5 g of p-toluenesulfonic acid dissolved in 50 g of methanol was added as a crosslinking catalyst, reacted for 3 hours, cooled and neutralized. Thereafter, the slurry was filtered and washed. Furthermore, the dyeing crosslinking step was performed again to obtain colored crosslinked polymer particles C.

  The colored crosslinked polymer particles C were heat-treated at 180 ° C. for 16 hours in order to dehydrate and condense silanol groups derived from hydrolyzable silyl groups present inside the particles. As a result, colored crosslinked polymer particles D having silanol groups derived from hydrolyzable silyl groups on the particle surface (those that did not bond because they were in contact with the dispersion medium) were obtained.

  Colored polymer particles D (10 g) are dispersed in 30 g of methyl ethyl ketone, charged with 3 g of methacryloyl isocyanate, reacted at room temperature for 30 minutes, washed, and colored crosslinked polymer having a polymerizable vinyl group on the surface of colored polymer particles D Particle E was obtained.

  To the colored crosslinked polymer particles E (1 g), 20 g of methyl ethyl ketone, 10 g of 2-ethylhexyl methacrylate, 0.2 g of benzoyl peroxide were charged into a reactor, heated to 80 ° C. under a nitrogen stream, and reacted for 60 minutes, Charged electrophoretic particles F having an average particle size of 2.4 μm were obtained. 97 g of an aliphatic hydrocarbon solvent (trade name: Isopar H, manufactured by ExxonMobil) was added to and dispersed in the charged electrophoretic particles F (3 g) to obtain a charged electrophoretic particle dispersion A1.

  The electrophoretic display device 10 shown in FIG. 1 was manufactured as follows by setting the size of one pixel to 60 μm × 60 μm and the number of pixels to 300 × 300. As the substrate 3a and the substrate 3b, non-alkali glass having a thickness of 0.5 mm was used. A polyacrylic resin layer whitened with titanium oxide was disposed as the colored resin layer 4 on the substrate 3a. On the surface of the colored resin layer 4, gold having a thickness of 20 nm was deposited to form the first electrode 5a. First, an insulating colored resin layer 6 (width 5 μm, height 2 μm) in which carbon black is added to a polyacrylic resin to blacken the pixel boundary is disposed. Further, a partition wall 7 (width 5 μm, height 18 μm) made of a photosensitive epoxy resin (trade name: SU-8) was disposed on the insulating colored resin layer 6. A second electrode 5b was formed on the surface of the partition wall 7 by depositing gold having a thickness of 20 nm.

  Next, the coating film 8 was formed on the surface of the 1st electrode 5a and the 2nd electrode 5b. 9 g of an aliphatic hydrocarbon solvent (trade name: Isopar H, manufactured by ExxonMobil) was added to 1 g of silicon-hydrogen bond-containing polysiloxane (trade name: SH1107) to prepare a mixed solution. Thereafter, the mixed solution was applied onto the surfaces of the first electrode 5a and the second electrode 5b, and the reaction temperature was room temperature (22 ° C.) and the reaction time was 1 hour. Further, the coated portion was washed away with Isopar H and dried to form a coating film 8 on the surfaces of the first electrode 5a and the second electrode 5b.

  Next, an adhesive layer 9 was formed on the upper surface of the partition wall 7, charged with the charged electrophoretic particle dispersion A1 in the pixel, and the substrate 3b was adhered to the upper surface of the partition wall 7 with the adhesive layer 9 sealed. . Thus, the electrophoretic display device of Example 1 was manufactured.

(Comparative Example 1)
A polydimethylsiloxane-containing polyacrylic resin (trade name: Papyres, manufactured by NATCO Corporation) was applied on the surfaces of the first electrode 5a and the second electrode 5b in place of the coating film 8 so as to have a thickness of 1 μm. An electrophoretic display device of Comparative Example 1 was produced in the same manner as Example 1 except for the above.

(Example 2)
A 2000 ml separable flask equipped with a stirrer, condenser, thermometer and gas inlet tube was charged with 157 g of styrene, 157 g of γ-methacryloxypropyltrimethoxysilane, 79 g of polyvinylpyrrolidone, 1170 g of methanol and 41 g of water, and under nitrogen flow. The temperature was raised to 62 ° C. Thereafter, 12 g of 4,4′-azobis (2-methylbutyronitrile) was added and subjected to precipitation polymerization for 6 hours to obtain a slurry A containing crosslinkable polymer particles having hydrolyzable silyl groups.

  To 100 g of the methanol dispersion from which the unreacted polymerizable vinyl monomer present in the slurry A was removed, a solution obtained by dissolving 11.5 g of p-toluenesulfonic acid in 50 g of methanol as a crosslinking catalyst was reacted for 3 hours, Cooled and neutralized. Thereafter, the slurry was filtered and washed to obtain crosslinked polymer particles G.

  The crosslinked polymer particle G was subjected to heat treatment at 180 ° C. for 16 hours in order to cause dehydration condensation of hydrolyzable silyl group-derived silanol groups present inside the particles. As a result, crosslinked polymer particles H having silanol groups derived from hydrolyzable silyl groups on the particle surfaces (those that were not bonded because they were in contact with the dispersion medium) were obtained.

  Crosslinked polymer particles H (10 g) are dispersed in 30 g of methyl ethyl ketone, charged with 3 g of methacryloyl isocyanate, reacted at room temperature for 30 minutes, washed, and then crosslinked polymer particles having a polymerizable vinyl group on the surface of the crosslinked polymer particles H. I got.

  For cross-linked polymer particles I (1 g), 20 g of methyl ethyl ketone, 10 g of 2-ethylhexyl methacrylate, 0.2 g of benzoyl peroxide were charged into a reactor, heated to 80 ° C. in a nitrogen stream, and reacted for 60 minutes to obtain an average. Charged electrophoretic particles J with a particle size of 2.4 μm were obtained. 97 g of an aliphatic hydrocarbon solvent (trade name: Isopar H, manufactured by ExxonMobil) was added to and dispersed in the charged electrophoretic particles J (3 g) to obtain a charged electrophoretic particle dispersion A2.

  An electrophoretic display device of Example 2 was produced in the same manner as in Example 1 except that the charged electrophoretic particle dispersion A2 was used instead of the charged electrophoretic particle dispersion A1.

(Example 3)
82 g of tetramethylol methane triacrylate, 31 g of divinylbenzene and 37 g of acrylonitrile were uniformly mixed, 14 g of aniline black was added thereto as a pigment, and the pigment was uniformly dispersed over 48 hours using a bead mill. To this pigment-dispersed monomer mixture, 2 g of benzoyl peroxide is uniformly mixed. This is added to 850 g of an aqueous polyvinyl alcohol solution having a concentration of 3% by weight. The mixture is stirred well, and the particle size is about 1-8 μm with a homogenizer. Suspended in the form of fine particles.

  This suspension was transferred to a 2 liter separable flask equipped with a thermometer, a stirrer, and a reflux condenser, heated to 85 ° C. with stirring in a nitrogen atmosphere, and subjected to a polymerization reaction for 7 hours. The polymerization reaction was carried out by heating for 3 hours. Thereafter, the polymerization reaction liquid was cooled, and the produced colored polymer fine particles were filtered, washed, dried, and subjected to classification treatment to obtain colored polymer particles K having an average particle size of 2.4 μm.

  Colored polymer particles K (10 g), 80 g of dimethyl sulfoxide, and 40 g of methyl methacrylate were added to a separable flask and sufficiently dispersed with a sonicator, and then stirred uniformly. Nitrogen gas was introduced into the system and stirring was continued at 30 ° C. for 1 hour. To this, 70 g of a 0.1 mol / L ceric ammonium nitrate solution prepared with a 1N nitric acid aqueous solution was added and reacted for 5 hours. Thereafter, after completion of the polymerization, the reaction solution was taken out, filtered, washed and dried to obtain colored polymer particles L.

  Colored polymer particles L (10 g) are dispersed in 30 g of methyl ethyl ketone, charged with 3 g of methacryloyl isocyanate, reacted at room temperature for 30 minutes, washed, and colored crosslinked polymer having a polymerizable vinyl group on the surface of the colored polymer particles L Particle M was obtained.

  To the colored crosslinked polymer particles M (1 g), 20 g of methyl ethyl ketone, 10 g of 2-ethylhexyl methacrylate, 0.2 g of benzoyl peroxide were charged into a reactor, heated to 80 ° C. under a nitrogen stream, and reacted for 60 minutes, Charged electrophoretic particles N having an average particle size of 2.4 μm were obtained. 97 g of an aliphatic hydrocarbon solvent (trade name: Isopar H, manufactured by ExxonMobil) was added to and dispersed in the charged electrophoretic particles N (3 g) to obtain a charged electrophoretic particle dispersion A3.

  An electrophoretic display device of Example 3 was manufactured in the same manner as in Example 1 except that the charged electrophoretic particle dispersion A3 was used instead of the charged electrophoretic particle dispersion A1.

Example 4
An electrophoretic display device of Example 4 was manufactured in the same manner as Example 1 except that ITO was used instead of gold as the material of the first electrode 5a and the second electrode 5b.

(Example 5)
An electrophoretic display device of Example 5 was produced in the same manner as in Example 1 except that 1-butanethiol was used in place of silicon-hydrogen bond-containing polysiloxane (trade name: SH1107) as the material of the coating film 8. .

(Example 6)
An electrophoretic display device of Example 6 was produced in the same manner as in Example 1 except that 1-octanethiol was used in place of silicon-hydrogen bond-containing polysiloxane (trade name: SH1107) as the material of the coating film 8. .

(Example 7)
An electrophoretic display device of Example 7 was produced in the same manner as in Example 1 except that 1-dodecanethiol was used in place of silicon-hydrogen bond-containing polysiloxane (trade name: SH1107) as the material of the coating film 8. .

(Example 8)
An electrophoretic display device of Example 8 was produced in the same manner as in Example 1 except that dibutyl disulfide was used in place of silicon-hydrogen bond-containing polysiloxane (trade name: SH1107) as the material of the coating film 8.

Example 9
Example 1 except that 1-hexyltrimethoxysilane was used in place of silicon-hydrogen bond-containing polysiloxane (trade name: SH1107) as the material of the coating film 8 and the reaction temperature was 80 ° C. and the reaction time was 3 hours. In the same manner as in Example 1, an electrophoretic display device of Example 9 was produced.

(Comparative Example 2)
An electrophoretic display device of Comparative Example 2 was produced in the same manner as in Example 1 except that the coating film 8 was not formed on the surfaces of the first electrode 5a and the second electrode 5b.

(Evaluation results)
A sine wave voltage having an effective voltage value of 30 Vrms and a frequency of 1 Hz was applied to the electrophoretic display devices of Examples 1 to 9 and Comparative Examples 1 and 2. In Examples 1 to 9 and Comparative Example 1, the charged particles were driven without sticking to the first electrode and the second electrode. However, in Comparative Example 2, the charged particles adhered to the first electrode or the second electrode and were not driven.

  Thereafter, the voltage was released when the charged particles were attracted to the partition wall. In Examples 1 to 9, the charged particles adhered to the partition walls to obtain memory properties. However, in Comparative Example 1, the charged particles did not adhere to the partition walls and moved to the surface of the substrate, and the memory property was not obtained.

  Moreover, the resistance value was measured by applying a tester to the surfaces of the electrodes of the electrophoretic display devices of Examples 1 to 9 and Comparative Examples 1 and 2. In Comparative Example 1, since the insulating resin layer was formed on the surface of the electrode, the resistance value was large. On the other hand, in Examples 1-9, the resistance value equivalent to the comparative example 2 in which nothing was formed on the surface of the electrode was obtained.

  The evaluation results are shown in Table 1. In the driveability column in the table, ◯ indicates that the charged particles are driven, and × indicates that the charged particles are attached to the electrode and are not driven. In the column of memory property in the table, ◯ indicates that charged particles adhere to the partition when the voltage is released, and × indicates that charged particles do not adhere to the partition when the voltage is released.

  DESCRIPTION OF SYMBOLS 1 ... Charged particle (for example, black), 1a ... Charged particle (for example, white), 1b ... Charged particle (for example, red), 1c ... Charged particle (for example, green), 1d ... Charged particle (for example, blue), 2 ... Insulating fluid 5a ... 1st electrode, 5b ... 2nd electrode, 8 ... Coating film, 10 ... Electrophoretic display.

Claims (6)

A coating film formed on the surface of the electrode of an electrophoretic display device comprising an electrode for moving charged particles dispersed in an insulating fluid by an electric field,
The coating film is a molecular film containing a molecule having at least one active functional group and a hydrophobic functional group among a thiol group, a disulfide group, a hydrosilyl group and a hydrolyzable silyl group.   The coating film according to claim 1, wherein the hydrophobic functional group is an alkyl group or a silicon-containing group.   The coating film according to claim 1 or 2, wherein the molecule is alkanethiol.   The coating film of Claim 1 or 2 whose said molecule | numerator is Si-H bond containing polysiloxane.   The coating film according to claim 1 or 2, wherein the molecule is a silane coupling agent.   The coating film according to claim 1, wherein the electrode is made of a material containing at least one of gold and ITO.

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