An electrophoretic coating liquid, an electrophoretic display panel, and a display device

Abstract

The application discloses an electrophoretic coating liquid, an electrophoretic display panel and a display device. Compared with the prior art, the application adds an enal compound into the electrophoretic coating liquid, the aldehyde group and the double bond of the enal compound react with gelatin and resin monomers or unsaturated resin in the microcapsule wall respectively to form an aldehyde amine condensation and addition reaction, so that a firm molecular structure is formed, the microcapsules are uniformly dispersed in the electrophoretic coating layer, the dispersibility of the microcapsules in the electrophoretic coating layer is improved, appearance defects such as empty points, scratches, convex points and bad points of the electrophoretic coating layer are avoided, and the yield of the electrophoretic display panel is improved. In addition, the enal compound is bonded with the microcapsule wall and the bonding strength between the microcapsules and the glue material is enhanced, so that the cracking of the coating layer caused by bending, folding and the like can be avoided.

Description

Technical Field

[0001] The present invention relates to the field of electrophoretic display technology, and in particular to an electrophoretic coating liquid, an electrophoretic display panel and a display device. Background Art

[0002] Electrophoretic image display (EPID) utilizes the phenomenon of colloidally dispersed particles migrating under the influence of an electric field. Its advantages include high contrast, wide viewing angle, high display brightness, low price, and ease of implementing large-scale displays. However, its disadvantages include poor reliability, difficulty in controlling threshold characteristics, and, in particular, the tendency of particles in the dispersed system to aggregate and precipitate, resulting in a short lifespan for EPID displays. In recent years, the Massachusetts Institute of Technology (MIT) Media Lab has proposed the concept of electronic ink (encapsulated electrophoretic ink), or microencapsulated electrophoretic display technology. Leveraging the principles of electrophoretic display, it innovatively encapsulates pigment particles and a dark dye solution within microcapsules, enabling electrophoretic display within the microcapsules. This suppresses the aggregation and sedimentation of electrophoretic particles larger than the capsule size, improving their stability and extending their lifespan. Electronic ink is an ink-like suspension that can achieve reversible, bistable, and flexible display under the action of an external electric field. It is a flexible display material and technology that integrates physics, chemistry, electronics and other disciplines. It has the advantages of good visibility, low power consumption, strong information loading capacity, easy portability, low manufacturing cost, and no electromagnetic radiation. It can fundamentally solve the shortcomings of existing flat panel display technology. Summary of the Invention

[0003] In view of this, the technical problem to be solved by the present invention is to provide an electrophoretic coating liquid, an electrophoretic display panel and a display device with good dispersion performance.

[0004] The present invention provides an electrophoretic coating liquid, comprising:

[0005] 100 parts by weight of microcapsules modified with alkenal compounds;

[0006] 1 to 20 parts by weight of resin monomer and / or unsaturated resin;

[0007] 50 to 100 parts by weight of solvent.

[0008] Specifically, the alkenal compound-modified microcapsules are prepared according to the following method:

[0009] The microcapsules are mixed with an aldehyde compound in an organic solvent, the pH value of the reaction system is adjusted to alkaline, and the reaction is heated to obtain microcapsules modified with the aldehyde compound;

[0010] The capsule wall of the microcapsule comprises gelatin and a negatively charged polymer material.

[0011] Specifically, the alkenal compound is as shown in formula (I):

[0012]

[0013] Wherein, said n is an integer from 0 to 5;

[0014] R is a substituted or unsubstituted C1-C10 alkyl group, or a substituted or unsubstituted C6-C20 aryl group;

[0015] The substituents in the substituted C1-C10 alkyl group and the substituted C6-C20 aryl group are each independently selected from one or more of a C1-C5 alkyl group and a C1-C5 alkoxy group.

[0016] The present invention further provides an electrophoretic display panel, comprising a transparent conductive substrate, an electrophoretic coating layer and a driving backplane arranged in sequence; the electrophoretic coating layer is formed by the electrophoretic coating liquid mentioned above.

[0017] The present invention further provides a display device comprising the above-mentioned electrophoretic display panel.

[0018] Compared with the prior art, the present invention adds olefinic compounds to the electrophoretic coating liquid, and the two reactive active sites, the aldehyde group and the double bond in the olefinic compounds, respectively undergo aldehyde-amine condensation and addition reactions with gelatin and resin monomers or unsaturated resins in the microcapsule wall to form a strong molecular structure, thereby uniformly dispersing the microcapsules in the electrophoretic coating layer, improving the dispersibility of the microcapsules in the electrophoretic coating layer, thereby avoiding appearance defects such as empty spots, scratches, convex spots, and bad spots in the electrophoretic coating layer, and improving the yield of the electrophoretic display panel; in addition, the olefinic compounds respectively form bonds with the microcapsule wall, thereby enhancing the bonding strength between the microcapsules and the adhesive material, and avoiding cracking of the coating layer due to bending, folding, etc.

[0019] Furthermore, the present invention uses acrylic monomers, acrylic ester monomers, polypropylene, modified polypropylene, polypropylene ester and modified polypropylene ester as adhesive substances, thereby improving the optical properties of the electrophoretic coating layer.

[0020] Furthermore, the present invention adopts ultraviolet curable resin to improve the flatness and yield of the electrophoretic coating layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of an existing electrophoretic display panel;

[0022] Figure 2A schematic diagram of a specific structure of the electrophoretic display panel provided by the present invention;

[0023] Figure 3 A schematic diagram of the electrophoretic coating solution provided by the present invention;

[0024] Figure 4 A schematic diagram of a specific structure of the electrophoretic display panel provided by the present invention;

[0025] Figure 5 This is a schematic diagram of the electrophoretic coating liquid provided by the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0027] Current electronic inks use spherical, transparent, and smooth microcapsules of 100 to 2000 microns to encapsulate a dielectric suspension containing charged electrophoretic particles. These capsules are dispersed in a polyurethane adhesive to form a dispersed system, which is then coated or printed on a flexible ITO conductive film to form a principle-based flexible EPID electronic paper. Figure 1 ( Figure 1 In the figure, 1 is a PET layer, 2 is an ITO layer, 3 is an adhesive layer, 4 is a microcapsule, 5 is an electrophoretic coating layer, and 6 is a backplane). However, the inventors found that the capsules cannot be well dispersed in the polyurethane adhesive, and there are disadvantages such as agglomeration of capsules within a large size range, which makes it difficult to apply the coating when using coating methods including roller coating, screen printing, and spraying. The coating film has a poor appearance and various appearance defects, including empty spots, scratches, convex spots, and bad spots, resulting in a low yield. In addition, due to the poor adhesion of the existing electrophoretic coating layer, it is necessary to set a thick adhesive layer of about 100 to 250 μm to bond it to the backplane or transparent electrode.

[0028] In order to solve the problem that the capsules are difficult to disperse in the resin and have poor adhesion, the present invention provides an electrophoretic coating liquid, comprising:

[0029] 100 parts by weight of microcapsules modified with alkenal compounds;

[0030] 1 to 20 parts by weight of resin monomer and / or unsaturated resin;

[0031] 50 to 100 parts by weight of solvent.

[0032] The electrophoretic coating liquid provided by the present invention contains olefinic compounds. The two reactive sites, the aldehyde group and the double bond in the olefinic compounds, respectively undergo aldehyde-amine condensation and addition reactions with gelatin and resin monomers or unsaturated resins in the microcapsule wall to form a strong molecular structure, thereby uniformly dispersing the microcapsules in the electrophoretic coating layer and improving the dispersibility of the microcapsules in the electrophoretic coating layer. In addition, the olefinic compounds respectively form bonds with the microcapsule wall, thereby enhancing the bonding strength between the microcapsules and the adhesive material, and avoiding cracking of the coating layer due to bending, folding, etc.

[0033] See also Figures 2 to 4 , Figure 2 and Figure 4 Two specific structural schematic diagrams of electrophoretic display panels are provided, where 1 is a transparent substrate, 2 is a transparent electrode layer, 4 is a microcapsule, 5 is an electrophoretic coating layer, 6 is a driving backplane, and the right side is an enlarged structural schematic diagram of the microcapsule wall; Figure 3 and Figure 5 A schematic diagram of the electrophoretic coating solution provided by the present invention is provided.

[0034] According to the present invention, microcapsules modified with enal compounds are dispersed in the electrophoretic coating liquid; the particle size of the microcapsules modified with enal compounds can be specifically 30 to 300 μm, more specifically 30 to 200 μm, and even more specifically 30 to 100 μm; in the present invention, the microcapsules modified with enal compounds refer to microcapsules formed by chemical bonds between the enal compounds and the microcapsule wall, and specifically, the enal compounds and the microcapsule wall are bonded by aldehyde-amine condensation.

[0035] In the present invention, the enal compound-modified microcapsules are prepared specifically according to the following method: mixing microcapsules and enal compounds in an organic solvent, adjusting the pH value of the reaction system to alkaline, and heating the reaction to obtain enal compound-modified microcapsules.

[0036] The capsule wall of the microcapsule comprises gelatin and a negatively charged polymer material; the mass ratio of the gelatin to the negatively charged polymer material can be specifically 1:1; the negatively charged polymer material is a negatively charged polymer material well known to those skilled in the art that can form a capsule wall with gelatin, and there is no special limitation. In the present invention, it is specifically natural plant gum and / or synthetic cellulose; more specifically, the natural plant gum can be one or more of gum arabic, peach gum, pectin, apricot gum and alginic acid; the synthetic cellulose can be carboxymethyl cellulose; the capsule wall of the first microcapsule comprises a suspension and a plurality of charged polymers dispersed in the suspension. Pigment particles; the charged color ions can be inorganic and / or organic particles; the inorganic particles can be one or more of titanium dioxide, zinc white, and cadmium yellow; the organic particles can be one or more of scarlet red, toluidine red, phthalocyanine blue, and pigment yellow; the solvent in the suspension is an organic solvent; the organic solvent can be epoxy compounds (such as decane oxide), aromatic compounds (such as toluene and naphthalene), halogenated hydrocarbons (such as tetrachloroethylene), and their oligomers (such as polytrichloroethylene with a degree of polymerization of 2 to 10). Fluorinated (or perfluorinated) organic solvents are more suitable as suspension solutions due to their high density, good chemical stability, and environmental friendliness. In the present invention, more specifically, the suspension also includes a charge control agent; the charge control agent can be an organic sulfate (such as calcium dodecylbenzenesulfonate, barium dinonylnaphthalenesulfonate), a metal soap, an organic amine, an organic phosphate, or a phosphate ester. To enhance the efficiency of the charge control agent, a certain amount of a charge adjuvant, such as a polyhydroxy compound or an amino alcohol compound, can also be added.

[0037] The microcapsules are mixed with an alkenyl compound in an organic solvent; the alkenyl compound is specifically as shown in formula (I):

[0038]

[0039] Wherein, n is an integer of 0 to 5, specifically 0, 1, 2 or 3. R is a substituted or unsubstituted C1-C10 alkyl group or a substituted or unsubstituted C6-C20 aryl group; the substituents in the substituted C1-C10 alkyl group and the substituted C6-C20 aryl group are each independently selected from one or more of C1-C5 alkyl groups and C1-C5 alkoxy groups. Specifically, R is a substituted or unsubstituted C2-C6 alkyl group or a substituted or unsubstituted C6-C10 aryl group; the substituents in the substituted C2-C6 alkyl group and the substituted C6-C10 aryl group are each independently selected from one or more of C1-C3 alkyl groups and C1-C3 alkoxy groups. More specifically, the alkenal compound is selected from 2-hexenal and / or cinnamaldehyde. The alkenal compound and the microcapsule are mixed according to a molar ratio of gelatin to the alkenal compound in the capsule wall of the microcapsule of 1: (0.8-1.5), more specifically 1: (1-1.2); the organic solvent can be an organic solvent for the resin of a person skilled in the art without any special restrictions, and can specifically be an alcohol solvent and / or dimethylformamide; the alcohol solvent can specifically be ethanol; the mixing time can specifically be 10-90 minutes, more specifically 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes or 80 minutes.

[0040] After mixing, the pH of the system is adjusted to alkaline, and the mixture is heated for reaction. In the present invention, the pH of the system can be adjusted to 8-9. In the present invention, the pH of the system can be adjusted using methods well known to those skilled in the art, without any particular limitation. Specifically, an alkali metal hydroxide, more specifically potassium hydroxide and / or sodium hydroxide, can be added. The alkaline catalyst can be added in the form of an aqueous solution. The mass concentration of the aqueous solution of the alkali metal catalyst can be specifically 20% to 50%, more specifically 30%, 40%, or 50%. The heating temperature can be 80°C to 100°C, and the heating time can be specifically 8-15 hours, more specifically 10-12 hours.

[0041] After the reaction is completed, the organic solvent is removed to obtain microcapsules modified with enal compounds.

[0042] According to the present invention, the electrophoretic coating liquid contains a resin monomer and / or an unsaturated resin. One end of the olefinic aldehyde compound reacts with the gelatin in the microcapsule wall and the other end reacts with the double bond in the resin monomer and / or the unsaturated resin to form a strong molecular structure, thereby stably dispersing the microcapsules in the electrophoretic coating layer. The resin monomer and / or unsaturated resin may be any of the types of resin monomers and / or unsaturated resins known to those skilled in the art, and are not particularly limited. In the present invention, specifically, the resin monomer may be an acrylic monomer and / or an acrylate monomer; the acrylate monomer includes one or more of at least one of methyl acrylate, methyl methacrylate, tert-butyl acrylate, cyclohexyl methacrylate, ethyl methacrylate, n-butyl methacrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, and tridecyl 2-methylpropenoate; the unsaturated resin may be one or more of polyacrylic acid resin, polyacrylate resin, silicone resin, and epoxy resin, and more specifically, may be one or more of polyacrylic acid, polyacrylate, polyurethane, silicone resin, epoxy resin, poly-2-ethylhexyl acrylate, polyacrylic acid, polymethacrylic acid, polyitaconic acid, polyhydroxyethyl methacrylate, polyhydroxypropyl methacrylate, polypropylene glycol acrylate, polyacrylamide, polymethacrylamide, polyvinyl alcohol, and poly-N-vinyl pyrrolidone. The type of the resin monomer and / or unsaturated resin can also be selected according to process requirements. For example, to simplify the process and meet leveling requirements, a resin monomer and / or unsaturated resin with lower viscosity can be selected. To avoid the impact of thermal curing on the device, a UV-curable resin monomer and / or unsaturated resin can be selected. The number average molecular weight of the unsaturated resin can be specifically 500,000 to 1.2 million, more specifically 600,000 to 1,000,000, and further specifically 800,000 to 1,000,000. The degree of polymerization of the unsaturated resin can be 7,000 to 17,000. The content of the resin monomer and / or unsaturated resin in the electrophoretic coating liquid can be specifically 5 to 20 parts by weight, and further specifically 8 to 15 parts by weight.

[0043] According to the present invention, the electrophoretic coating liquid may optionally further include an initiator; the mass of the initiator is specifically 1% to 5% of the mass of the resin monomer and / or the unsaturated resin. The initiator is preferably one or more of a peroxide initiator, an azo initiator and a photoinitiator; the peroxide initiator is any peroxide initiator well known to those skilled in the art and is not particularly limited. In the present invention, it can be specifically one or more of potassium persulfate, sodium persulfate and ammonium persulfate; the azo initiator is any azo initiator well known to those skilled in the art and is not particularly limited. In the present invention, it can be specifically azobisisobutyronitrile and / or azobisisoheptanenitrile; the photoinitiator is a common UV photoinitiator. Specifically, in the present invention, it can be one or more of 2-hydroxy-methylphenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, benzoin dimethyl ether, 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide, benzophenone, and 2-isopropylthioxanthone.

[0044] According to the present invention, the solvent can be any solvent well known to those skilled in the art that can be used as an electrophoretic coating liquid, without any special restrictions, and can specifically be one or more of water, alcohol solvents, ketone solvents, ester solvents and toluene; the alcohol solvent can be any alcohol solvent well known to those skilled in the art, without any special restrictions, and can specifically be methanol and / or ethanol in the present invention; the ketone solvent can be any ketone solvent well known to those skilled in the art, without any special restrictions, and can specifically be one or more of ketone, acetone, butanone, and methyl isobutyl ketone in the present invention; the ester solvent can be any ester solvent well known to those skilled in the art, without any special restrictions, and can specifically be one or more of ethyl acetate, acetone ethyl acetate, butyl acetate, and isobutyl acetate.

[0045] The present invention also provides a method for preparing the electrophoretic coating liquid, comprising: mixing microcapsules modified with olefinic aldehyde compounds, resin monomers and / or unsaturated resins with a solvent, and heating the mixture for reaction to obtain the electrophoretic coating liquid.

[0046] The present invention has no particular limitation on the sources of all raw materials, and any commercially available raw materials are sufficient. The types and contents of the enal compound-modified microcapsules, resin monomers and / or unsaturated resins and solvents are the same as those described above and will not be repeated here.

[0047] The microcapsules modified with olefinic aldehyde compounds, resin monomers and / or unsaturated resins are mixed with a solvent; the mixing speed can be specifically 100 to 500 rpm, more preferably 200 to 400 rpm; the mixing time can be specifically 10 to 90 minutes, more specifically 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes or 80 minutes.

[0048] After mixing, the mixture can be heated to obtain an electrophoretic coating liquid; the unsaturated bonds of the outer wall of the microcapsule modified with the aldehyde compound are promoted to react with the resin monomer and / or unsaturated resin; the heating temperature is preferably 80°C to 100°C; the heating time is preferably 0.5 to 5 hours, more preferably 1 to 3 hours.

[0049] The present invention further provides an electrophoretic display panel, comprising a transparent conductive substrate, an electrophoretic coating layer and a driving backplane arranged in sequence; the electrophoretic coating layer is formed by the electrophoretic coating liquid mentioned above.

[0050] According to the present invention, the transparent conductive substrate includes a transparent substrate and a transparent electrode layer; the transparent substrate can be specifically made of materials such as polyethylene terephthalate (PET), polyethylene (PE), polyimide (PI), polyethylene naphthalate (PEN), etc.; the transparent conductive electrode can be specifically an indium tin oxide (ITO) film, nanosilver wire or graphene film.

[0051] An electrophoretic coating layer is provided on the transparent electrode; the thickness of the electrophoretic coating layer is specifically 10-1000 μm, further specifically 50-800 μm, further specifically 50-500 μm, further specifically 50-300 μm, further specifically 50-200 μm.

[0052] A driving backplane is provided on the electrophoretic coating layer; the driving backplane can be any driving backplane well known to those skilled in the art without any special limitation. Specifically, the driving backplane can be formed by manufacturing a thin film transistor driving circuit using a semiconductor process on a substrate such as glass, PI, or PET.

[0053] According to the present invention, further specifically, the driving backplane and the transparent conductive substrate are both connected to a circuit for applying electrical signals to both sides of the electrophoretic coating layer. The driving electrodes may be pixel electrodes of an electrophoretic display device, and the controller controls the voltage signals on the driving electrodes to control the display of the electrophoretic coating layer.

[0054] In another specific embodiment provided by the present invention, a first coating layer is provided between the transparent conductive substrate and the electrophoretic coating layer; the first coating layer is formed by a first coating liquid; the first coating liquid comprises: 1 to 20 parts by weight of a resin monomer and / or an unsaturated resin; and 50 to 100 parts by weight of a solvent. The types of the resin monomer and / or unsaturated resin and the solvent are the same as those described above and will not be repeated here. More specifically, the first coating liquid has the same components as the electrophoretic coating liquid except that it does not contain microcapsules. The thickness of the first coating layer can specifically be 10 to 50 μm.

[0055] In another specific embodiment provided by the present invention, a second coating layer is disposed between the electrophoretic coating layer and the driver backplane. The second coating layer comprises: 1 to 20 parts by weight of a resin monomer and / or an unsaturated resin; and 50 to 100 parts by weight of a solvent. The types of the resin monomer and / or unsaturated resin and solvent are the same as those described above and are not further described here. The thickness of the second coating layer is 10 to 50 μm.

[0056] By providing a coating layer without microcapsules between the electrophoretic coating layer and the driving backplane and / or the transparent conductive substrate, the bonding force between the electrophoretic coating layer and the driving backplane and / or the transparent conductive substrate can be improved.

[0057] The present invention also provides a method for preparing the electrophoretic display panel, comprising the following steps: forming a film of the electrophoretic coating liquid on a transparent conductive substrate, then covering the electrophoretic coating film with a driving backplane, and curing the film to obtain the electrophoretic display panel.

[0058] In the present invention, the film-forming method is any method well known to those skilled in the art and is not particularly limited. The method can be selected according to the viscosity of the electrophoretic coating liquid. For example, if the viscosity of the electrophoretic coating liquid is relatively low, inkjet printing can be used. If the viscosity of the electrophoretic coating liquid is relatively high, coating can be performed or screen printing can be used.

[0059] In the present invention, the curing method is any method well known to those skilled in the art and is not particularly limited. To avoid heat treatment affecting the flatness of the electrophoretic coating layer, a photocuring method is preferably used to improve the flatness and yield of the electrophoretic coating layer.

[0060] The present invention further provides a display device comprising the above-mentioned electrophoretic display panel.

[0061] In the present invention, the display device can be a mobile phone display, a computer display, a TV display, a smart watch display, a smart car display, a VR or AR helmet display, a display of various smart devices, etc.

[0062] The following will be a clear and complete description of the technical solutions of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0063] The degree of hydrolysis of the gelatin used in the embodiment is 5% at room temperature. The degree of hydrolysis can be increased by heating, and it can be completely hydrolyzed to 100% at 60°C. The molecular weight of the polypropylene used in the embodiment is 800,000 to 1,000,000; the molecular weight of the polymethacrylic acid used is 800,000 to 1,000,000.

[0064] Example 1

[0065] 1.1 Add 5g of gelatin to 100mL of deionized water and stir to dissolve at 42°C. Simultaneously, stir and dissolve 5g of gum arabic in 100mL of deionized water at 40°C. After the gelatin is completely dissolved, add the electrophoresis display solution, adjust the speed, and stir and disperse for 45 minutes. Then add the completely dissolved gum arabic solution and adjust the speed to an appropriate level to continue stirring and dispersing for 30 minutes. Then adjust the pH to 4.5 with a 10% aqueous acetic acid solution, adjust the speed to an appropriate level, and stir and disperse for another 30 minutes. Lower the temperature to 10°C for 3 hours. Add a 50% glutaraldehyde solution and simultaneously increase the reaction temperature to 25°C. Allow the microcapsules to crosslink and cure for 10 hours. Collect the microcapsules and select microcapsules with a particle size of 50-80μm using a vibrating sieve with a microporous filter.

[0066] 1.2 The microcapsules obtained in 1.1 were mixed with 2-hexenal in ethanol at a molar ratio of gelatin to 2-hexenal of 1:1 for 1 hour to fully dissolve. Then, an aqueous sodium hydroxide solution was added to adjust the pH value of the reaction system to 8-9. The reaction was heated to 100°C for 12 hours. The solvent was removed to obtain 2-hexenal-modified microcapsules.

[0067] 1.3 Formula of electrophoretic coating fluid:

[0068]

[0069] The 2-hexenal-modified microcapsules, polyacrylic acid, 1-hydroxycyclohexylphenyl ketone and ethyl acetate were mixed and heated to 80° C. for reaction for 1 hour to obtain an electrophoretic coating solution.

[0070] 1.4 The electrophoretic coating liquid is applied to the ITO conductive glass to a coating thickness of 50 μm, a TFT driving backplane is placed on the coating, and UV curing is performed to obtain an electrophoretic display.

[0071] Example 2

[0072] Formula of electrophoretic coating fluid:

[0073]

[0074]

[0075] The 2-hexenal-modified microcapsules were prepared in Example 1. The preparation methods of the electrophoretic coating liquid and the electrophoretic display were the same as those in Example 1.

[0076] Example 3

[0077] Formula of electrophoretic coating fluid:

[0078]

[0079] The 2-hexenal-modified microcapsules were prepared in Example 1. The preparation methods of the electrophoretic coating liquid and the electrophoretic display were the same as those in Example 1.

[0080] Example 4

[0081] 4.1 Add 5g of gelatin to 100mL of deionized water and stir to dissolve at 42°C. Simultaneously, stir and dissolve 5g of gum arabic in 100mL of deionized water at 40°C. After the gelatin is completely dissolved, add the electrophoresis display solution, adjust the speed, and stir and disperse for 45 minutes. Then add the completely dissolved gum arabic solution and adjust the speed to an appropriate level to continue stirring and dispersing for 30 minutes. Then adjust the pH to 4.5 with a 10% aqueous acetic acid solution, adjust the speed to an appropriate level, and stir and disperse for another 30 minutes. Lower the temperature to 10°C for 3 hours. Add a 50% glutaraldehyde solution and simultaneously increase the reaction temperature to 25°C. Allow the microcapsules to crosslink and cure for 10 hours. Collect the microcapsules and select microcapsules with a particle size of 50-80μm using a vibrating sieve with a microporous filter.

[0082] 4.2 The microcapsules obtained in 4.1 were mixed with trans-cinnamaldehyde in ethanol at a molar ratio of gelatin to trans-cinnamaldehyde of 1:1 for 1 hour to fully dissolve. Then, an aqueous sodium hydroxide solution was added to adjust the pH of the reaction system to 8-9. The reaction was heated to 100°C for 12 hours. The solvent was removed to obtain cinnamaldehyde-modified microcapsules.

[0083] 4.3 Formula of electrophoretic coating fluid:

[0084]

[0085]

[0086] The cinnamaldehyde-modified microcapsules, polymethacrylic acid, 1-hydroxycyclohexylphenyl ketone and ethyl acetate were mixed and heated to 80° C. for reaction for 1 hour to obtain an electrophoretic coating solution.

[0087] 4.4 The electrophoretic coating liquid is applied to the ITO conductive glass to a coating thickness of 50 μm, a TFT driving backplane is placed on the coating, and UV curing is performed to obtain an electrophoretic display.

[0088] Example 5

[0089] Formula of electrophoretic coating fluid:

[0090]

[0091] The cinnamaldehyde-modified microcapsules were prepared in Example 4. The preparation methods of the electrophoretic coating liquid and the electrophoretic display were the same as those in Example 4.

[0092] Example 6

[0093] Formula of electrophoretic coating fluid:

[0094]

[0095] The cinnamaldehyde-modified microcapsules were prepared in Example 4. The preparation methods of the electrophoretic coating liquid and the electrophoretic display were the same as those in Example 4.

[0096] Example 7

[0097] The electrophoretic coating liquid is the same as that in Example 3. The first coating liquid and the second coating liquid have the same composition as the electrophoretic coating liquid, except that they do not contain microcapsules.

[0098] The first coating liquid is applied to the ITO conductive glass with a coating thickness of 10 μm. After UV curing, the electrophoretic coating liquid is applied with a coating thickness of 50 μm. After UV curing, the second coating liquid is applied with a coating thickness of 10 μm. A TFT driving backplane is placed on the coating layer and UV cured to obtain an electrophoretic display.

[0099] Comparative Example 1

[0100] The formula of the electrophoretic coating liquid is the same as that of Example 1, except that the microcapsules obtained in 1.1 of Example 1 are added.

[0101] The preparation method of the electrophoretic display is the same as that of Example 1.

[0102] Comparative Example 2

[0103] The formula of the electrophoretic coating liquid is the same as that of Example 2, except that the microcapsules obtained in 1.1 of Example 1 are added.

[0104] The preparation method of the electrophoretic display is the same as that of Example 1.

[0105] The electrophoretic displays of Examples 1-6 and Comparative Examples 1-2 were subjected to a T-peel strength test, and the average value was taken. As shown in Table 1, the electrophoretic coating solution provided by the present invention can achieve a peel strength comparable to that of the comparative examples, even with the use of less adhesive and tackifying resin. When the colloid dosage is equal, the examples have a greater peel strength advantage. The comparative examples are more susceptible to cohesive failure during electrophoretic coating formation due to the weak microcapsules. However, the electrophoretic coating layer produced by the method used in this application has stronger cohesion, significantly less susceptible to external forces.

[0106] Table 1 T-peel strength test results of electrophoretic display

[0107]

[0108] Coating yield:

[0109] The coating yield was determined by analyzing the appearance of the electrophoretic display. The analysis results are shown in Table 2. The analyzed samples were the electrophoretic displays prepared in Examples 1 to 6 and Comparative Examples 1 to 2. The results show that the test samples of Examples 1 to 6 had excellent appearance, with no appearance defects such as bad pixels, shrinkage cavities, black spots, and empty spots. In contrast, the samples of Comparative Examples 1 to 2 showed obvious bad pixels, shrinkage cavities, and black spot aggregation, and even horizontal stripes, which affected the coating yield and increased losses. This shows that the technical solution of the present application can effectively reduce capsule agglomeration and uneven dispersion, and is more conducive to the close arrangement of capsules, reducing gaps, and is beneficial to improving photoelectric performance and membrane utilization.

[0110] Table 2 Coating yield analysis results

[0111]

[0112] Bending performance test:

[0113] The bending performance of the electrophoretic display obtained in Examples 1 to 6 was tested, and the results were as follows: bending radius ≤ 2 mm, bending angle: 0 to 180°, and bending times > 200,000 times.

[0114] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. An electrophoretic coating liquid, characterized in that include: 100 parts by weight of microcapsules modified with alkenal compounds; 1-20 parts by weight of resin monomer and / or unsaturated resin; 50-100 parts by weight of solvent; The microcapsules modified with the alkenal compounds are formed by bonding the alkenal compounds to the microcapsule walls through aldehyde-amine condensation; The alkenal compound is shown in formula (I): Formula (I); Wherein, said n is an integer of 0 to 5; R is a substituted or unsubstituted C1~C10 alkyl group, or a substituted or unsubstituted C6~C20 aryl group; The substituents in the substituted C1-C10 alkyl group and the substituted C6-C20 aryl group are each independently selected from one or more of a C1-C5 alkyl group and a C1-C5 alkoxy group; The resin monomer is selected from acrylic monomers and / or acrylate monomers; The unsaturated resin is selected from one or more of polyacrylic resins, polyacrylate resins, silicone resins and epoxy resins.

2. The electrophoretic coating liquid according to claim 1, characterized in that The alkenal compound-modified microcapsules are prepared according to the following method: The microcapsules are mixed with an aldehyde compound in an organic solvent, the pH value of the reaction system is adjusted to alkaline, and the reaction is heated to obtain microcapsules modified with the aldehyde compound; The capsule wall of the microcapsule comprises gelatin and a negatively charged polymer material.

3. The electrophoretic coating liquid according to claim 1, characterized in that The n is 0, 1, 2 or 3.

4. The electrophoretic coating liquid according to claim 1, characterized in that R is a substituted or unsubstituted C2~C6 alkyl group, or a substituted or unsubstituted C6~C10 aryl group; The substituents in the substituted C2-C6 alkyl group and the substituted C6-C10 aryl group are each independently selected from one or more of a C1-C3 alkyl group and a C1-C3 alkoxy group.

5. The electrophoretic coating liquid according to claim 1, characterized in that The alkenal compound is selected from 2-hexenal and / or cinnamaldehyde.

6. The electrophoretic coating liquid according to claim 2, characterized in that The organic solvent is selected from alcohol solvents and / or dimethylformamide; and / or, adjusting the pH value of the reaction system to 8-9; And / or, the temperature of the heating reaction is 80°C to 100°C; And / or, the heating reaction time is 8 to 15 hours.

7. The electrophoretic coating liquid according to claim 2, characterized in that: The mass ratio of gelatin to negatively charged polymer material in the capsule wall of the microcapsule is 1:1; The molar ratio of gelatin to alkenal compounds in the capsule wall of the microcapsule is 1:(0.8-1.5).

8. The electrophoretic coating liquid according to claim 2, characterized in that: The negatively charged polymer material is selected from natural plant gum and / or synthetic cellulose; The natural plant gum is selected from one or more of gum arabic, peach gum, pectin, apricot gum and alginic acid; The synthetic cellulose is selected from carboxymethyl cellulose.

9. The electrophoretic coating liquid according to claim 2, characterized in that: The unsaturated resin is selected from one or more of polyacrylic acid, polyacrylate, polyurethane, silicone resin, epoxy resin, poly(2-ethylhexyl acrylate), polyacrylic acid, polymethacrylic acid, polyitaconic acid, poly(hydroxyethyl methacrylate), poly(hydroxypropyl methacrylate), polypropylene glycol, polyacrylamide, polymethacrylamide, polyvinyl alcohol and poly-N-vinyl pyrrolidone.

10. The electrophoretic coating liquid according to claim 1, characterized in that The electrophoretic coating liquid further includes an initiator; the mass of the initiator is 1% to 5% of the mass of the resin monomer and / or the unsaturated resin.

11. The electrophoretic coating liquid according to claim 1, characterized in that The solvent is selected from one or more of water, alcohol solvents, ketone solvents, ester solvents and toluene.

12. A method for preparing the electrophoretic coating liquid according to claim 1, characterized in that: The following steps are involved: The microcapsules modified with olefinic aldehyde compounds, resin monomers and / or unsaturated resins are mixed with a solvent and heated for reaction to obtain an electrophoretic coating liquid.

13. The preparation method according to claim 12, characterized in that The temperature of the heating reaction is 80° C. to 100° C.; the time of the heating reaction is 0.5 to 5 h.

14. An electrophoretic display panel, characterized in that: The invention comprises a transparent conductive substrate, an electrophoretic coating layer and a driving backplane arranged in sequence; the electrophoretic coating layer is formed by the electrophoretic coating liquid according to any one of claims 1 to 11.

15. The electrophoretic display panel according to claim 14, wherein: The thickness of the electrophoretic coating layer is 10-1000 μm.

16. The electrophoretic display panel according to claim 14, wherein: A first coating layer is provided between the transparent conductive substrate and the electrophoretic coating layer; The first coating layer is formed by a first coating liquid; The first coating solution comprises: 1-20 parts by weight of resin monomer and / or unsaturated resin; 50-100 parts by weight of solvent; And / or, a second coating layer is provided between the electrophoretic coating layer and the driving backplane; the second coating layer is formed by a second coating liquid; The second coating liquid comprises: 1-20 parts by weight of resin monomer and / or unsaturated resin; 50-100 parts by weight of solvent 17. The electrophoretic display panel according to claim 16, wherein: The thickness of the first coating is 10-50 μm; and / or, The thickness of the second coating layer is 10-50 μm.

18. A display device, characterized in that: The electrophoretic display panel comprises the electrophoretic display panel according to any one of claims 14 to 17.

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