Sealing film composition for sealing microcells of electro-optical devices

Abstract

The present invention relates to an aqueous sealing composition comprising a combination of a polymer, a poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer and a polyurethane, a conductive filler, and a water-soluble ether within an aqueous carrier. The aqueous sealing composition can be used to form a sealing film in an electro-optical device having (a) a plurality of microcells filled with charged particles and a non-polar fluid, and (b) an electro-optical material layer comprising a sealing film, wherein the electro-optical material layer is disposed between two electrode layers. The device exhibits excellent electro-optical performance.

Description

Technology Field

[0001] Related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 281,345 filed on November 19, 2021. The entire contents of all patents, published applications, or other published works referenced herein are incorporated by reference.

[0003] Field of invention

[0004] The present invention relates to a sealing film that can be used in an electro-optical device such as an electrophoretic display. The sealing film comprises a poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer, a polyurethane, a conductive filler, and a water-soluble ether. The sealing film can be formed by curing or drying an aqueous sealing composition. Background Technology

[0005] The term “electro-optical,” as applied to materials or displays, is used herein in the conventional sense in imaging technology to refer to a material having first and second display states that differ in at least one optical property, namely, a material that changes from a first display state to a second display state by applying an electric field to the material. The optical property is generally a color perceptible to the human eye, but may be other optical properties such as optical transmittance, reflectance, luminescence, or, in the case of machine-readable displays, pseudo-color in the sense of a change in reflectance of electromagnetic wavelengths outside the visible range.

[0006] The terms “bistable” and “bistable” are used herein in the ordinary sense of the art to refer to a display comprising a display element having first and second display states that differ in at least one optical characteristic, and after the given element is driven to assume the first or second display state by an addressing pulse of a finite period, and after the addressing pulse is terminated, the state will persist for at least several times, e.g., at least four times, which is the minimum duration required to change the state of the display element. U.S. Patent No. 7,170,670 indicates that some particle-based electrophoretic displays capable of grayscale are stable in intermediate gray states as well as extreme black and white states, and that other types of electro-optical devices are likewise stable. While it is appropriate to call these types of displays “multistable” rather than “bistable,” for convenience, the term “bistable” may be used herein to encompass both bistable and multistable displays.

[0007] One type of electro-optical device that has been the subject of intensive research and development for several years is the particle-based electrophoretic display, in which multiple charged particles move through a fluid under the influence of an electric field. Compared to liquid crystal displays, electrophoretic displays can possess characteristics such as good brightness and contrast ratio, a wide viewing angle, state bistable, and low power consumption.

[0008] Numerous patents and applications assigned to or filed in the names of Massachusetts Institute of Technology (MIT), E Ink Corporation, E Ink California, LLC, and related companies describe various technologies used in encapsulated microcell electrophoresis and other electro-optical media. Encapsulated electrophoretic media comprise numerous small capsules, each capsule comprising an inner phase containing electrophoretic transport particles in a fluid medium and a capsule wall surrounding the inner phase. Typically, capsules are immobilized within a polymer binder to form a coherent layer located between two electrodes. In microcell electrophoretic displays, charged particles and fluids are not encapsulated within microcapsules but are instead retained within a carrier medium, typically within a polymer film, in multiple cavities formed therein.

[0009] The technology described in these patents and applications includes the following:

[0010] (a) electrophoretic particles, fluids and fluid additives; see, e.g., U.S. Patents No. 7,002,728 and 7,679,814;

[0011] (b) capsules, binders, and encapsulation processes; see, for example, U.S. Patents No. 6,922,276 and 7,411,719;

[0012] (c) Microcell structure, wall material, and method of forming a microcell; see, for example, U.S. Patents No. 7,072,095 and No. 9,279,906;

[0013] (d) Method for filling and sealing microcells; see, for example, U.S. Patents No. 7,144,942, No. 7,005,468 and No. 7,715,088, and U.S. Patent Application Publications No. 2004-0120024 and No. 2004-0219306;

[0014] (e) a film and subassembly comprising an electro-optical material; see, for example, U.S. Patents No. 6,982,178 and No. 7,839,564;

[0015] (f) a backplane, an adhesive layer, and other auxiliary layers used in a display and a method; see, for example, U.S. Patents No. 7,116,318 and No. 7,535,624;

[0016] (g) Color formation and color adjustment; see, for example, U.S. Patents No. 7,075,502 and No. 7,839,564;

[0017] (h) a method for driving a display; see, for example, U.S. Patents No. 7,012,600 and 7,453,445;

[0018] (i) Applications of displays; see, for example, U.S. Patents No. 7,312,784 and No. 8,009,348; and

[0019] (j) a non-electrophoretic display as described in U.S. Patent No. 6,241,921 and U.S. Patent Application Publication No. 2015 / 0277160; and applications of encapsulation and microcell technology other than displays; see, e.g., U.S. Patent No. 7,615,325 and U.S. Patent Application Publications No. 2015 / 0005720 and No. 2016 / 0012710.

[0020] The contents of all the aforementioned references are incorporated herein by reference in their entirety.

[0021] Structures having multiple sealed microcells containing a dispersion of charged pigment particles in a nonpolar fluid are commercially used in electro-optical devices. Microcells are also known in the literature as microcavities or microcups. A general process for manufacturing a sealed microcell structure for an electro-optical device comprises: (a) a step of manufacturing a polymer sheet having multiple microcavities through microembossing, wherein each microcavity has an opening; (b) a step of filling the microcavities with an electrophoretic medium, which is a dispersion containing charged pigment particles in a nonpolar fluid; and (c) a step of sealing the microcavities with an aqueous sealing composition to form a sealing film. The sealed microcavities containing the electrophoretic medium form an electro-optical material layer of the device. The electro-optical material layer is placed between the front electrode and the back electrode. When an electric field is applied to the electrophoretic medium through these electrodes, the pigment particles move through the electrophoretic medium to generate an image. The sealing film plays a critical role in the function and performance of the device. First, since the sealing film contacts the electrophoretic medium to seal the interior of the microcavity, it must (1) be substantially insoluble in the nonpolar fluid of the electrophoretic medium and (2) serve as an excellent barrier against the nonpolar fluid to prevent the nonpolar fluid from diffusing out of the microcell throughout the device's lifespan. Second, the sealing film must not absorb a significant amount of moisture from the environment. That is, it must prevent environmental moisture from entering the electrophoretic medium of the device, as such moisture can negatively affect the device's electro-optical performance. The sealing film must be mechanically resilient throughout the device's effective lifespan and possess an optimal volume resistivity that remains substantially constant over time. If the barrier properties of the sealing film against the nonpolar fluid deteriorate, the fluid in the electrophoretic medium decreases, and the sealing film sags.Finally, the electrical conductivity of the sealing film is important, among other components, because the potential is applied throughout the device and propagates through the sealing film. The technical problem of providing an aqueous sealing composition that forms a sealing film with these characteristics is difficult because different formulation strategies may be required depending on the purpose. For example, blocking properties for non-polar fluids generally require more hydrophilic components, whereas these components absorb more moisture from the environment. If the electrical conductivity of the sealing film is low, power consumption increases during device operation, and if the conductivity is too high, image quality may degrade due to blooming. Therefore, there is a need for an aqueous sealing composition that forms a sealing film optimized for improved blocking properties for non-polar fluids, reduced moisture absorption, and improved electro-optical performance. The inventors of the present invention have discovered that a sealing film composition comprising a combination of a poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer, a polyurethane, conductive carbon black, and a water-soluble ether provides a sealing film having excellent electro-optical performance and excellent color.

[0022] Summary of the Invention

[0023] In one embodiment, the present invention relates to a sealing film comprising: a water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer having a content of 15% to 60% by weight based on the weight of the sealing film, wherein the poly(vinyl alcohol) homopolymer has a degree of hydrolysis of 90% to 99.5% and the poly(vinyl alcohol-co-ethylene) copolymer has a degree of hydrolysis of 90% to 99.5% and an ethylene content of less than 10%; a polyurethane having a content of 7% to 29% by weight based on the weight of the sealing film; carbon black having a content of 5% to 70% by weight based on the weight of the sealing film; and a water-soluble ether having a content of 0.5% to 25% by weight based on the weight of the sealing film.

[0024] The poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer may have an average molecular weight of 1,000 to 1,000,000 daltons. The poly(vinyl alcohol) polymer or poly(vinyl alcohol-co-ethylene) copolymer may have a degree of hydrolysis of 92% to 99%. The polyurethane polymer may have a number average molecular weight of 1,000 to 2,000,000 daltons. The polyurethane may be an ester polyurethane, a polycarbonate polyurethane, or a combination thereof. The total surface energy of the sealing film may be lower than 60 mN / m. The interfacial tension between the water-soluble poly(vinyl alcohol) polymer or poly(vinyl alcohol-co-ethylene) copolymer and the polyurethane may be less than 2 mN / m. The sealing film may further comprise an organic silicone wetting agent.

[0025] The water-soluble ether has a molecular weight of 75 to 5,000 daltons and optionally contains a hydroxyl group. The water-soluble ether is represented by the following chemical formula I, chemical formula II, or chemical formula III:

[0026]

[0027] In the formula, n is 1 to 145; R1 is hydrogen, methyl, or ethyl group; R2, R3, R4, R5, R6, and R7 are independently selected from the group consisting of hydrogen, linear or branched alkyl groups comprising 1 to 6 carbon atoms, phenyl, and benzyl groups; Formula I comprises at least one ether functional group; Formula II comprises at least one ether functional group; and Formula III comprises at least one ether functional group. For Formula I, n may be 1 to 10. The sealing film is 10 8 to 10 10 It can have a volume resistivity of Ohm.cm.

[0028] In another embodiment, the present invention relates to an electro-optical device comprising: a conductive layer; a microcell layer comprising a plurality of microcells, wherein each microcell comprises an opening, each microcell comprises an electrophoretic medium, and the electrophoretic medium comprises charged particles among a non-polar carrier; a sealing film extending across the opening of each microcell; an adhesive layer; and an electrode layer. The sealing film comprises a water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer having a content of 15% to 60% by weight based on the weight of the sealing film, wherein the poly(vinyl alcohol) homopolymer has a degree of hydrolysis of 90% to 99.5%, and the poly(vinyl alcohol-co-ethylene) copolymer has a degree of hydrolysis of 90% to 99.5% and an ethylene content of less than 10%. Polyurethane in an amount of 7 to 29 weight% based on the weight of the sealing film; carbon black in an amount of 5 to 70 weight% based on the weight of the sealing film; and a water-soluble ether in an amount of 0.5 to 25 weight% based on the weight of the sealing film, wherein the water-soluble ether has a molecular weight of 70 to 5,000 daltons and optionally includes hydroxyl groups. The electrophoretic medium may comprise at least three types of charged pigment particles, and one type of charged particle has a color selected from the group consisting of blue, green, red, cyan, magenta, and yellow.

[0029] In another aspect, the present invention comprises, as an aqueous sealing composition, a water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer having an amount of 14% to 55% by weight based on the weight of the sealing composition excluding water, wherein the poly(vinyl alcohol) homopolymer has a degree of hydrolysis of 90% to 99.5% and the poly(vinyl alcohol-co-ethylene) copolymer has a degree of hydrolysis of 90% to 99.5% and an ethylene content of less than 10%; a polyurethane having an amount of 6% to 27% by weight based on the weight of the aqueous sealing composition excluding water; and carbon black having an amount of 5% to 64% by weight based on the weight of the aqueous sealing composition excluding water. The present invention relates to an aqueous sealing composition comprising: a water-soluble ether having a molecular weight of 75 to 5,000 daltons and optionally containing hydroxyl groups, in an amount of 1.0 wt% to 40 wt% based on the weight of the aqueous sealing composition excluding water; and water in an amount of 20 wt% to 95 wt% based on the weight of the aqueous sealing composition. The aqueous sealing composition may further comprise a crosslinking agent in an amount of 0.1 wt% to 8 wt% based on the weight of the aqueous sealing composition excluding water, wherein the crosslinking agent is a polyisocyanate, a polycarbodiimide, a polyfunctional aziridine, a silane coupling agent, a boron / titanium / zirconium-based crosslinking agent, or melamine formaldehyde. The aqueous sealing composition may further comprise a rheology modifier in an amount of 0.05 wt% to 5 wt% based on the weight of the aqueous sealing composition excluding water. Brief explanation of the drawing

[0030] Figure 1 shows a side view of a microcell structure before multiple microcells are filled and sealed. FIG. 2 shows a side view of an example of an electro-optical device including a microcell structure. FIG. 3 shows a side view of an example of a front plane stacked assembly that can be used to form an electro-optical device including a microcell structure. FIG. 4 shows a side view of an example of a double-sided sheet that can be used to form an electro-optical device including a microcell structure. Figure 5 illustrates a method for manufacturing microcells using a roll-to-roll process. FIGS. 6A and 6B illustrate in detail the fabrication of a microcell using photolithographic exposure through a photomask of a conductive film coated with a thermosetting precursor. FIGS. 6C and 6D illustrate in detail other embodiments of manufacturing a microcell array using photolithography. In FIGS. 6C and 6D, a combination of top and bottom exposure is used so that a partition wall in one lateral direction is cured by top photomask exposure and a partition wall in the other lateral direction is cured by bottom exposure through an opaque base conductor film. Figures 7A-7D illustrate the steps of filling and sealing an array of microcells. Figures 8A-8D illustrate various components configured to evaluate the volume resistivity of a sealing film. Figure 8E illustrates the waveform used to evaluate the volume resistivity of a sealing film. Figure 9 shows the electrical impedance spectroscopy results of the control and the sealing film of the present invention. Figure 10 illustrates the structure of an electro-optical device used to evaluate the electro-optical performance of an aqueous sealing composition. FIG. 11 illustrates the waveform used to determine the color range of the present invention and the contrast electro-optical device. FIG. 12 shows a side view of the structure of an electro-optical device used to evaluate the blocking characteristics of an aqueous sealing composition. Figures 13A-13D show microscopic images of a microcell in which blocking characteristics were evaluated. Figure 14 shows a microscopic image of a sealing film comprising a combination of poly(vinyl alcohol-co-ethylene) copolymer and polyurethane having different interfacial tensions. Specific details for implementing the invention

[0031] Detailed description of the invention

[0032] As used herein, “molecular weight” refers to the weight-average molecular weight of a compound unless otherwise specified. Molecular weight is measured using gel permeation chromatography, which is an industry standard method.

[0033] The degree of hydrolysis of a poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer is the ratio of the number of moles of vinyl alcohol groups to the sum of the number of moles of vinyl alcohol groups and the number of moles of vinyl acetate groups in the polymer. Thus, in the example of the simplified polyvinyl alcohol formula (Formula IV) provided below, the degree of hydrolysis is calculated by Formula 1 below.

[0034] Degree of hydrolysis = 100 xp / (p+q) Equation 1

[0035] Polyvinyl alcohol manufacturers generally report the degree of hydrolysis of their products. This parameter affects important physical properties of the polymer, such as the water solubility of the polymer and the water resistance of the corresponding dry film. Titration methods are used to measure the degree of hydrolysis of polyvinyl alcohol (homopolymers and copolymers). Detailed information on the method is described in Method JIS K 6726 (Japanese Standards Association, 94th edition, October 20, 2017).

[0036]

[0037] The terms "sealing film" and "sealing layer" are synonyms and are used interchangeably in relation to electro-optical devices.

[0038] The terms "adhesive film" and "adhesive layer" are synonyms and are used interchangeably in relation to electro-optical devices.

[0039] Unless otherwise specified, the disclosed content of the components of the sealing film is calculated as a weight percentage of the components based on the weight of the sealing film excluding water. Unless otherwise specified, the disclosed content of the components of the aqueous sealing composition is calculated as a weight percentage of the components based on the weight of the aqueous sealing composition excluding water.

[0040] A. Structure of microcells

[0041] FIG. 1 illustrates a side view of a structure before a plurality of microcells (100) are filled and sealed. Each microcell includes a bottom (101), a partition wall (102), and an opening (103).

[0042] B. Structure of an electro-optical device including a microcell structure

[0043] FIG. 2 illustrates a side view of an example of an electro-optical device (200) including microcells. This example of the electro-optical device (200) includes a first light-transmitting electrode layer (210), a microcell layer (220), a sealing film (230), an adhesive layer (240), and a second electrode layer (250). The microcell layer includes a plurality of microcells defined by a bottom (221) and a partition wall (222). Each of the plurality of microcells includes an electrophoretic medium (225) containing charged particles in a non-polar fluid. The microcells are sealed by a sealing film (230) that spans the openings of the plurality of microcells. The second electrode layer (250) is connected to the sealing film (230) by an adhesive layer (240). The plurality of microcells, sealed by the sealing layer (230) and containing the electro-optical medium (225), comprise an electro-optical material layer of the electro-optical device (200). A source of the electric field can connect the first light-transmitting electrode layer (210) to the second electrode layer (250). When the electric field is applied across the electrophoretic material layer, charged particles move through the electrophoretic medium to generate an image that can be observed by an observer looking from the viewing side (215) of the electro-optical device (200). Any primer layer not shown in FIG. 2 may be placed between the first light-transmitting electrode layer (210) and a plurality of microcells (222).

[0044] An example of an electro-optical device illustrated in FIG. 2 may be constructed by a front planar laminate (300) illustrated in FIG. 3. The front planar laminate (300) comprises a first light-transmitting electrode layer (310), a microcell layer (320) comprising a plurality of microcells (325), a sealing film (330), an adhesive layer (340), and a release sheet (360). Each of the plurality of microcells comprises an electrophoretic medium (325) containing charged particles in a non-polar fluid. The microcells (325) are sealed by a sealing film (330) that spans the openings of the plurality of microcells. The release sheet (360) is connected to the sealing film (330) by the adhesive layer (340). When the release sheet (360) is removed, the surface of the adhesive layer (340) is exposed, which can be connected to a second electrode layer to form an electro-optical device. Any primer layer not shown in FIG. 3 may be disposed between the first light-transmitting electrode layer (310) and a plurality of microcells (330).

[0045] An example of an electro-optical device illustrated in FIG. 2 may also be constructed by a double release sheet (400) illustrated in FIG. 4. The double release sheet (400) comprises a first release sheet (480), a first adhesive layer (470), a microcell layer (420) comprising a plurality of microcells (425), a sealing film (430), a second adhesive layer (440), and a second release sheet (460). Each of the plurality of microcells comprises an electrophoretic medium (425) containing charged particles in a non-polar fluid. The microcells are sealed by a sealing film (430) that spans the openings of the plurality of microcells. The first release sheet (480) is connected to the microcell layer (420) by the first adhesive layer (470). The second release sheet (460) is connected to the sealing film (430) by the second adhesive layer (440). When the first release sheet (480) is removed, the surface of the first adhesive layer (470) is exposed and can be connected to the first light-transmitting electrode layer. When the second release sheet (460) is removed, the surface of the second adhesive layer (440) is exposed and can be connected to the second electrode layer to form an electro-optical device. Any primer layer not shown in FIG. 4 may be disposed between the first adhesive layer (470) and the microcell layer (430).

[0046] C. Formation of microcell structure

[0047] Technology for constructing microcells.Microcells may be formed by a batch process or a continuous roll-to-roll process as disclosed in U.S. Patent No. 6,933,098. The latter provides a continuous, low-cost, high-throughput manufacturing technique for producing compartments for use in a variety of applications, including drug delivery and electrophoretic displays. Microcell arrays suitable for use in the present invention may be produced by microembossing as shown in FIG. 5. A lae mold (500) may be placed on the upper or lower part of the web (504) (not shown), but alternative placements are also possible. For example, see U.S. Patent No. 7,715,088, which is incorporated herein by reference in its entirety. A conductive substrate may be formed by forming a conductive film (501) on a polymer substrate that serves as a backing layer for the device. Then, a composition (502) comprising a thermoplastic, thermosetting, or a precursor thereof is coated over the conductive film. The thermoplastic resin or thermosetting precursor layer is embossed at a temperature higher than the glass transition temperature of the thermoplastic resin or thermosetting precursor layer by a roller, plate, or belt-shaped frame.

[0048] Thermoplastic or thermosetting precursors for the manufacture of microcells may be polyfunctional acrylates or methacrylates, vinyl ethers, epoxides and oligomers, or polymers thereof. A combination of polyfunctional epoxides and polyfunctional acrylates is also very useful for achieving desirable physico-mechanical properties. The flexural resistance of embossed microcells can be improved by adding crosslinkable oligomers that impart flexibility, such as urethane acrylates or polyester acrylates. The composition may comprise polymers, oligomers, monomers, and additives, or may comprise only oligomers, monomers, and additives. The glass transition temperature (T) for materials of this class g ) is generally in the range of about -70°C to about 150°C, or about -20°C to about 50°C. The micro-embossing process is generally T gIt is performed at a higher temperature. To control the microembossing temperature and pressure, a heated mold or a heated housing substrate to which the mold applies pressure can be used.

[0049] As illustrated in FIG. 5, the mold is released during or after the curing of the precursor layer to reveal an array of microcells (503). The curing of the precursor layer can be achieved by cooling, solvent evaporation, radiation, heat, or crosslinking by moisture. If the curing of the thermosetting precursor is achieved by ultraviolet light, the ultraviolet light can be radiated from the bottom or top of the web to a transparent conductive film as illustrated in both figures. Alternatively, a UV lamp may be placed inside the mold. In this case, the mold must be transparent so that UV rays can be radiated through a pre-patterned mold to the thermosetting precursor layer. The mold can be prepared by a suitable method such as etching or electroplating after a diamond turn process or a photoresist process. A master template for the mold can be manufactured by a suitable method such as electroplating. In the case of electroplating, a thin layer (typically 3000 Å) of a seed metal, such as chrome Inconel, is sputtered onto a glass base. Next, the mold is coated with a photoresist layer and exposed to UV light. A mask is placed between the UV light and the photoresist layer. The exposed areas of the photoresist are cured. Then, the unexposed areas are washed away with a suitable solvent. The remaining cured photoresist is dried and sputtered again as a thin seed metal layer. Then, the master is ready for electroforming. Common materials used for electroforming are nickel cobalt. Alternatively, the master can be made of nickel by electroforming or electroless nickel deposition. The bottom of the mold is typically about 50 to 400 microns. The master can also be made using other microengineering techniques, including electron beam marking, dry etching, chemical etching, laser marking, or laser interference, as described in the literature ["Replication techniques for micro-optics", SPIE Proc. Vol. 3099, pp. 76-82 (1997)].Alternatively, molds can be manufactured by photoprocessing using plastic, ceramic, or metal.

[0050] Before applying the UV-curable resin composition, the mold may be treated with a release agent to facilitate the release process. The UV-curable resin may be degassed before dispensing and may optionally contain a solvent. If a solvent is present, it evaporates easily. The UV-curable resin is dispensed onto the mold by appropriate methods such as coating, dipping, or pouring. The dispenser may be movable or stationary. A conductive film is superimposed on the UV-curable resin. If necessary, pressure may be applied to ensure proper bonding between the resin and the plastic and to control the thickness of the microcell base. Pressure may be applied using a lamination roller, vacuum forming, a press machine, or other similar means. If the mold is metallic and opaque, the plastic substrate is generally transparent to the chemical radiation used to cure the resin. Conversely, the mold may be transparent, and the plastic substrate may be opaque to chemical radiation. To transfer the molded feature well onto the transfer sheet, the conductive film must adhere well to the UV-curable resin and possess excellent release properties against the mold surface.

[0051] The microcell array of the present invention generally comprises a pre-formed conductive film, such as an indium tin oxide (ITO) conductor line, but other conductive materials such as silver or aluminum may be used. The conductive layer may be backed by or incorporated into a substrate, such as polyethylene terephthalate, polyethylene naphthalate, polyaramid, polyimide, polycycloolefin, polysulfone, epoxy, and composites thereof. The conductive film may be coated with a radiation-curable polymer precursor layer. Then, the film and the precursor layer are exposed to radiation in an imaging manner to form a microcell wall structure. After exposure, the precursor material is removed from the unexposed areas, and the cured microcell partition walls remain adhered to the conductive film / support web. Imaging exposure may be performed by UV or other forms of radiation through a photomask to create an image or a predetermined exposure pattern of the radiation-curable material coated on the conductive film. Although not generally required, the mask can be positioned and aligned with the conductive film, i.e., the ITO lines, so that the transparent mask portion is aligned with the space between the ITO lines and the opaque mask portion is aligned with the ITO material (for the microcell bottom area).

[0052] Photolithography. Microcells may also be produced using photolithography. A photolithography process for manufacturing a microcell array is illustrated in FIGS. 6A and 6B. As illustrated in FIGS. 6A and 6B, a microcell array (600) can be manufactured by exposing a radiation-curable material (601A) coated on a conductive electrode film (602) by a known method to ultraviolet light (or other alternative forms of radiation, such as an electron beam) through a mask (606) to form a partition wall (601B) corresponding to an image projected through the mask (606). The base conductive film (602) is preferably mounted on a support substrate base web (603) which may include a plastic material.

[0053] In the photomask (606) of FIG. 6A, the dark squares (604) represent opaque areas, and the spaces between the dark squares represent transparent areas (605) of the mask (606). Ultraviolet light is radiated into the radiation-curable material (601a) through the transparent areas (605). The exposure is preferably performed directly on the radiation-curable material (601a), that is, UV does not pass through the substrate (603) or base conductor (602) (top exposure). For this reason, the substrate (603) or conductor (602) does not need to be transparent to UV or other radiation wavelengths used.

[0054] As illustrated in FIG. 6B, the exposed area (601b) is cured, and the unexposed area (protected by the opaque area (604) of the mask (606)) is then removed by a suitable solvent or developer to form a microcell (607). The solvent or developer is selected from among solvents or developers commonly used to reduce the viscosity of radiation-curable materials or to dissolve them, such as methyl ethyl ketone (MEK), toluene, acetone, isopropanol, etc. Preparation of the microcell can similarly be performed by placing a photomask under a conductive film / substrate support web, in which case ultraviolet light is emitted from the bottom through the photomask, and the substrate must be transparent to radiation.

[0055] Image-based exposure.Another alternative method for manufacturing the microcell array of the present invention by image-based exposure is illustrated in FIGS. 6C and 6D. When using opaque conductor lines, the conductor lines can be used as a photomask for exposure from the bottom. Durable microcell partition walls are formed by additional exposure from the top through a second photomask having opaque lines perpendicular to the conductor lines. FIG. 6C illustrates the use of both top and bottom exposure principles to manufacture the microcell array (610) of the present invention. A base conductor film (612) is opaque and line-patterned. A radiation-curable material (611a) coated on the base conductor (612) and the substrate (613) is exposed from the bottom through a conductor line pattern (612) that acts as a first photomask. A second exposure is performed from the "top" through a second photomask (616) having a line pattern perpendicular to the conductor lines (612). The space (615) between the lines (614) is substantially transparent to ultraviolet light. In this process, the wall material (611b) is cured from bottom to top in one lateral direction and from top to bottom in a vertical direction to be combined to form an integral microcell (617). As shown in FIG. 6D, the unexposed area is removed by a solvent or developer as described above to reveal the microcell (617).

[0056] The microcell may be composed of a thermoplastic elastomer that has good compatibility with the microcell and does not interact with the medium. Examples of useful thermoplastic elastomers include diblock, triblock, and polyblock copolymers of the ABA and (AB)n types, wherein A is styrene, α-methylstyrene, ethylene, propylene, or norbornene, and B is butadiene, isoprene, ethylene, propylene, butylene, dimethylsiloxane, or propylene sulfide, and A and B cannot be identical in the chemical formula. The number n is ≥1, preferably 1-10. Particularly useful are diblock or triblock copolymers of styrene or ox-methylstyrene, such as SB (poly(styrene-b-butadiene)), SBS (poly(styrene-b-butadiene-b-styrene)), SIS (poly(styrene-b-isoprene-b-styrene)), SEBS (poly(styrene-b-ethylene / butylene-b-styrene)), poly(styrene-b-dimethylsiloxane-b-styrene), poly((α-methylstyrene-b-isoprene), poly(α-methylstyrene-b-isoprene-b-α-methylstyrene), poly(α-methylstyrene-b-propylene sulfide-b-α-methylstyrene), and poly(α-methylstyrene-b-dimethylsiloxane-b-α-methylstyrene). Commercially available styrene block copolymers, such as the Kraton D and G series (Kraton Polymer, Houston, Texas, USA), are particularly useful. Crystalline rubber, such as poly(ethylene-co-propylene-co-5-methylene-2-norbormenin) or EPDM (ethylene-propylene-diene terpolymer) rubber, such as Vistalon 6505 (Exxon Mobil, Houston, Texas, USA) and its graft copolymer, have also been found to be very useful.

[0057] Thermoplastic elastomers can be dissolved in solvents or solvent mixtures, which do not mix with the microcell carrier and exhibit a specific gravity lower than that of the carrier. Due to the excellent wettability of the microcell partition walls to fluids, solvents with low surface tension are preferred for the overcoating composition. Solvents or solvent mixtures with a surface tension lower than 35 dynes / cm are preferred. A surface tension lower than 30 dynes / cm is more desirable. Suitable solvents include alkanes (such as C alkanes, such as heptane, octane, or Exxon Chemical Company's Isopar solvent, nonane, decane, and their isomers). 6-12 Alkanes are preferred), cycloalkanes (such as cyclohexane and decalin, etc. C 6-12 Cycloalkanes are preferred), alkylbenzenes (mono- or di-C such as toluene, xylene, etc.) 1-6 Alkylbenzene is preferred), alkyl ester (C such as ethyl acetate, isobutyl acetate, etc.) 2-5 Alkyl esters are preferred) and C 3-5 Alkyl alcohols (e.g., isopropanol and its isomers) are included. Mixtures of alkylbenzenes and alkanes are particularly useful.

[0058] In addition to polymer additives, the polymer mixture may also include a wetting agent (surfactant). Wetting agents (e.g., FC surfactant from 3M Company, Zonyl fluorosurfactant from DuPont, fluoroacrylates, fluoromethacrylates, fluorosubstituted long-chain alcohols, perfluorosubstituted long-chain carboxylic acids and their derivatives, and Silwet silicone surfactant from OSi, Greenwich, Connecticut, USA) may also be included in the composition to improve the adhesion of the sealant to the microcells and provide a more flexible coating process. Crosslinking agents (e.g., bisazides such as 4,4'-diazidodiphenylmethane and 2,6-di-(4'-azidobenzal)-4-methylcyclohexanone), vulcanizing agents (e.g., 2-benzothiazolyl disulfide and tetramethylthiuram disulfide), multifunctional monomers or oligomers (e.g., hexanediol, diacrylate, trimethylolpropane, triacrylate, divinylbenzene, diallylphthalene), thermal initiators (e.g., dilaurolyl peroxide, benzoyl peroxide) and photoinitiators (e.g., isopropylthioxantone (ITX), Ciba-Geigy’s Irgacure 651 and Irgacure 369) are also very useful for improving the physicomechanical properties of sealing films through crosslinking or polymerization reactions during or after the overcoating process.

[0059] A microcell array such as the array (700) illustrated in FIG. 7A can be manufactured by any of the methods described above. As illustrated in the cross-sectional view of FIG. 7A-7D, a microcell partition wall (702) extends upward from the microcell bottom (701) and the conductive layer (710) to form an open microcell. In one embodiment, the conductive layer (710) is formed on or within the microcell bottom (701). FIG. 7A-7D illustrates the conductive layer (710) being continuous and running on the microcell bottom (701), but it is also possible for the conductive layer (710) to be continuous and run below or within the bottom (701) or interrupted by the microcell partition wall (702).

[0060] The microcells are then filled with an electrophoretic medium (725) containing charged particles in a nonpolar fluid to form a plurality of filled microcells (770). The microcells can be filled using various techniques. In some embodiments, a blade coating may be used to fill the microcells up to the depth of the microcell partition wall (702).

[0061] As illustrated in FIG. 7C, after charging, the microcell is sealed by applying an aqueous sealing composition to form a sealed microcell (780) comprising a sealing film (730). In some embodiments, the sealing process may include exposure to heat, dry hot air, or ultraviolet light. The sealing film must have good blocking properties against the non-polar fluid of the electrophoretic medium (725).

[0062] In an alternative embodiment, various individual microcells can be filled with a desired mixture using iterative photolithography. This process typically involves coating an array of empty microcells with a positively acting photoresist layer, exposing the positive photoresist in an imaging manner to randomly open a specific number of microcells, developing the photoresist, filling the open microcells with a desired mixture, and sealing the filled microcells using a sealing process. These steps can be repeated to produce sealed microcells filled with different mixtures. Through this procedure, large microcell sheets having a desired ratio or concentration of mixture can be formed.

[0063] Sealing of the filled microcells can be achieved in several ways. One approach involves mixing an aqueous sealing composition and an electrophoretic medium composition. The aqueous sealing composition may not mix with the electrophoretic composition and, preferably, has a lower specific gravity than the electrophoretic medium composition. The two compositions, the sealing composition and the electrophoretic medium composition, are thoroughly mixed and immediately coated onto multiple microcells using a precision coating mechanism such as a Meyer bar, gravure, doctor blade, slot coating, or slit coating. Excess liquid is scraped off with a wiper blade or a similar device. Fluid remaining on the upper surface of the partition walls of the microcells can be washed away using a small amount of a weak solvent or a solvent mixture such as isopropanol, methanol, or an aqueous solution thereof. The aqueous sealing composition is then separated from the electrophoretic medium composition and floats on top of the electrophoretic medium liquid composition. Alternatively, after a mixture of the electrophoretic medium composition and the aqueous sealing composition is filled into the microcell, a substrate may be laminated on top to control the metering of the mixture of compositions and to facilitate the phase separation of the aqueous sealing composition from the electrophoretic medium composition, thereby forming a uniform sealing film. The substrate used may be a functional substrate of the final structure or a sacrificial substrate that can be removed later, such as a release substrate. Then, a sealing film is formed by curing the aqueous sealing composition in situ (i.e., upon contact with the electrophoretic medium composition). Curing of the aqueous sealing composition may be achieved by ultraviolet or visible light, infrared or other forms of radiation such as electron beams. Alternatively, if a heat or moisture-curable aqueous sealing composition is used, heat or moisture may be used to cure the aqueous sealing composition.

[0064] In the second approach, an electrophoretic medium composition can be first filled into a microcell, and an aqueous sealing composition is subsequently overcoated onto the filled microcell. Overcoating can be performed by conventional coating and printing processes, such as blanket coating, inkjet printing, or other printing processes. In this approach, the sealing film is formed in situ by curing the aqueous sealing composition through solvent evaporation, radiation, heat, moisture, or interfacial reactions. UV curing after interfacial polymerization is useful for the sealing process. Interfacial polymerization forms a thin barrier layer at the interface, which significantly inhibits mixing between the electrophoretic medium composition and the sealing overcoat. Then, sealing is completed through a post-curing step, such as UV irradiation. Using an aqueous sealing composition with a lower specific gravity than the electrophoretic medium composition can further reduce the degree of mixing. Volatile organic solvents can be used to control the viscosity and thickness of the sealing overcoat. The rheology of the aqueous sealing composition can be adjusted for optimal sealability and coating properties. When a volatile solvent is used in the overcoat, it is desirable that it not be miscible with the solvent of the electrophoretic medium composition.

[0065] After the microcell is charged and sealed, the sealed microcell array may be laminated with a second electrode layer (750) comprising a plurality of electrodes as shown in FIG. 7D. The second electrode layer (750) is attached to a sealing film (730) to form an electro-optical device (790) as shown in FIG. 7D. An adhesive may be used to attach the second electrode layer (750) to the sealing film (730). The adhesive layer is not shown in FIG. 7D. The adhesive material of the adhesive layer may be electrically conductive. The adhesive of the adhesive layer may be a pressure-sensitive adhesive, a hot-melt adhesive, or a heat, moisture, or radiation-curable adhesive. The laminate adhesive may be post-cured by radiation, such as ultraviolet light, through the upper conductive layer if the upper conductive layer is transparent to radiation. In another embodiment, the plurality of electrodes may be directly bonded to the sealed array of microcells.

[0066] Generally, microcells can have any shape, and their size and shape can vary. Microcells can have substantially uniform size and shape within a system. However, microcells of various shapes and sizes may also exist. The openings of microcells can be circular, square, rectangular, hexagonal, or other shapes. The size of the partition areas between the openings can also vary. The dimensions of each individual microcell are approximately 1 × 10⁻⁶. 1 to about 1×10 6 ㎛ 2 , or about 1×10 2 to about 1×10 6 ㎛ 2 , or about 1×10 3 to about 1×10 5 ㎛ 2 It can be within the range of.

[0067] The depth of the microcell may be in the range of about 5 μm to about 200 μm, or about 10 μm to about 100 μm. The ratio of the opening area to the total area is in the range of 0.05 to 0.95, preferably 0.4 to 0.9.

[0068] Electrophoretic displays generally comprise an electrophoretic material layer and at least two other layers positioned opposite the electrophoretic material, one of which is an electrode layer. In most of these displays, both layers are electrode layers, and one or both of the electrode layers are patterned to define the pixels of the display. For example, one electrode layer may be patterned as elongated row electrodes, and the other as elongated column electrodes extending perpendicularly to the row electrodes, and pixels are defined by the intersection of the row electrodes and the column electrodes. Alternatively, and more generally, one electrode layer takes the form of a single continuous electrode, and the other electrode layer is patterned as a matrix of pixel electrodes, with each electrode defining one pixel of the display. In other types of electrophoretic displays intended for use with a stylus, print head, or similar movable electrode separated from the display, only one of the layers adjacent to the electro-optical material layer contains an electrode, and the layer opposite the electro-optical material layer is generally a protective layer to prevent the movable electrode from damaging the electro-optical material layer.

[0069] The manufacture of a three-layer electrophoretic display generally involves at least one lamination operation. For example, some of the aforementioned MIT and E Ink patents and applications describe a manufacturing process for an encapsulated electrophoretic display in which an encapsulated electrophoretic medium containing capsules in a binder is coated onto a flexible substrate comprising indium tin oxide (ITO) or a similar conductive coating on a plastic film. Separately, a backplane is prepared comprising an array of pixel electrodes and an array of suitable conductors for connecting the pixel electrodes to a driving circuit. To form the final display, a substrate having a layer of electro-optical material is laminated onto the backplane using a lamination adhesive.

[0070] The aforementioned U.S. Patent No. 6,982,178 describes a method for assembling a solid-state electro-optical display suitable for mass production. The core of this patent is to describe a so-called “Front Planar Laminate” (“FPL”) comprising, in order as illustrated in FIG. 3, a light-transmitting electrode layer, an electro-optical material layer in electrical contact with the light-transmitting electrode layer, an adhesive layer, and a release sheet. Typically, the light-transmitting electrode layer is performed on a light-transmitting substrate and is preferably flexible in the sense that the substrate can manually wrap a drum (e.g.) of 10 inches (254 millimeters) in diameter without permanent deformation. The term “light-transmitting” is used in this patent and herein to mean that the designated layer transmits sufficient light so that an observer can generally observe changes in the display state of the electrophoretic medium through the light-transmitting electrode layer and the adjacent substrate (if present); If the electrophoretic medium exhibits a change in reflectance at non-visible wavelengths, the term “light-transmittance” should naturally be interpreted to mean transmission at the relevant non-visible wavelengths. The substrate is generally a polymer film and generally has a thickness in the range of about 1 to about 25 mm (25 to 634 µm), preferably about 2 to about 10 mm (51 to 254 µm). The light-transmittance electrode layer may conveniently be a thin metal or metal oxide layer, such as aluminum or ITO, or a conductive polymer. Poly(ethylene terephthalate) (PET) films coated with aluminum or ITO are commercially available, such as “aluminumized Myla” (“Myla” is a registered trademark) from EI du Pont de Nemours & Company, Wilmington, Delaware, USA, and such commercial materials can be used with good results in full-planar laminates.The assembly of an electrophoretic display using such a front planar laminate can be carried out by removing the release sheet from the front planar laminate, bringing the adhesive layer into contact with the backplane so that the adhesive layer adheres to the backplane under effective conditions, and fixing the adhesive layer, the electro-optical material layer, and the light-transmitting electrode layer to the backplane. This process is suitable for mass production because the front planar laminate can generally be mass-produced using roll-to-roll coating technology and then cut into pieces of the required size for use with a specific backplane.

[0071] U.S. Patent No. 7,561,324 describes a so-called “double release sheet,” which is a substantially simplified version of the front planar laminate of the previously mentioned U.S. Patent No. 6,982,178. One form of the double release sheet comprises a layer of electro-optical material sandwiched between two adhesive layers, as illustrated in FIG. 4, with one or both of the adhesive layers covered by the release sheet. Another form of the double release sheet comprises a solid layer of electro-optical material sandwiched between two release sheets. Both forms of the double release film are intended for use in a process involving two separate laminations, which is generally similar to the process of assembling an electrophoretic display from the previously described front planar laminate, but generally, in the first lamination, the double release sheet is laminated to the front electrode to form a front sub-assembly, and then in the second lamination, the front sub-assembly is laminated to the backplane to form the final display, but the order of these two laminations can be reversed if desired.

[0072] U.S. Patent No. 7,839,564 describes a so-called “inverted front planar laminate” which is a variation of the front planar laminate described in the aforementioned U.S. Patent No. 6,982,178. This inverted front planar laminate may comprise, in sequence, at least one of a light-transmitting protective layer, a light-transmitting electrode layer, an adhesive layer, an electro-optical material layer, and a release sheet. Such an inverted front planar laminate is used to form an electro-optical device having a laminated adhesive layer between the electro-optical material layer and the light-transmitting electrode layer, and a second, generally thin adhesive layer may or may not exist between the electro-optical material layer and the backplane. Such an electro-optical display can combine excellent resolution and excellent low-temperature performance.

[0073] Electrophoretic medium

[0074] In the context of the present invention, the electrophoretic medium refers to a composition within a microcell. For display applications, the microcell may be filled with at least one type of charged pigment particles in a nonpolar fluid. The electrophoretic medium may comprise one type of charged particle or more than one type of particle having different colors, charges, and charge polarities. The charged particles move through the electrophoretic medium under the influence of an electric field applied across a layer of electro-optical material. The charged particles may be inorganic or organic pigments that have been polymerized surface-treated to enhance stability. The electrophoretic medium may comprise pigments having white, black, cyan, magenta, yellow, blue, green, red, and other colors. The electrophoretic medium may also comprise charge controllers, charge aids, rheology modifiers, and other additives. Examples of non-polar fluids include hydrocarbons, e.g., Isopar, decahydronaphthalene (DECALIN), 5-ethylidene-2-norbornene, fatty oils, paraffin oils, silicone fluids, aromatic hydrocarbons, e.g., toluene, xylene, phenylxylylethane, dodecylbenzene, or alkylnaphthalene; halogenated solvents, e.g., perfluorodecalin, perfluorotoluene, perfluoroxylene, dichlorobenzotrifluoride, 3,4,5-trichlorobenzotrifluoride, chloropentafluorobenzene, dichlorononane, or pentachlorobenzene; and perfluorinated solvents such as FC-43, FC-70, or FC-5060 of 3M Company, St. Paul, Minnesota, USA; low molecular weight halogen-containing polymers, e.g., poly(perfluoropropylene oxide) and poly(chlorotrifluoro-ethylene) of TCI America, Portland, Oregon, USA; e.g., River, New Jersey, USA Edge Material Halocarbon Product Corp.Halocarbon Oils, perfluoropolyalkyl ethers, such as Ausimont’s Galden or DuPont’s Krytox Oils and Greases K-Fluid Series, and Dow-Corning’s polydimethylsiloxane-based silicone oil (DC-200) are included.

[0075] The electrophoretic medium may include two types of charged particles having different colors, a first type of charged particle having a first charge polarity, and a second type of charged particle having a second charge polarity opposite to the first charge polarity. The first type of charged particle may be black, and the second type of charged particle may be white.

[0076] The electrophoretic medium may include three types of charged particles, all having different colors, a first type of charged particle having a first charge polarity, a second type of charged particle having a second charge polarity opposite to the first charge polarity, and a third type of charged particle having a third charge polarity identical to the first or second charge polarity. The first type of charged particle may be black, the second type of charged particle may be white, and the third type of charged particle may be selected from the group consisting of red, yellow, blue, cyan, magenta, green, and orange.

[0077] The electrophoretic medium may include four types of charged particles, all having different colors, a first type of charged particle having a first charge polarity, a second type of charged particle having a first charge polarity, a third type of charged particle having a second charge polarity opposite to the first charge polarity, and a fourth type of charged particle having a second charge polarity. The charge magnitude of the first type of particle may be higher than the charge magnitude of the second type of particle, and the charge magnitude of the third type of particle may be higher than the charge magnitude of the fourth type of particle. In one example, the first type of charged particle is cyan, the second type of charged particle is magenta, the third type of particle is yellow, and the fourth type of charged particle is white.

[0078] The electrophoretic medium may include four types of charged particles, all having different colors, a first type of charged particle having a first charge polarity, a second type of charged particle having a first charge polarity, a third type of charged particle having a first charge polarity, and a fourth type of charged particle having a second charge polarity opposite to the first charge polarity. The charge magnitudes of the first, second, and third particles may differ from one another. The charge magnitude of the third type of particle may be higher than the charge magnitude of the first type of particle, which may be higher than the charge magnitude of the second type of particle. In one example, the first type of particle is cyan, the second type of particle is magenta, the third type of particle is yellow, and the fourth type of particle is white.

[0079] The electrophoretic medium may include five types of charged particles, all having different colors, a first type of charged particle having a first charge polarity, a second type of charged particle having a first charge polarity, a third type of particle having a first charge polarity, a fourth type of particle having a second charge polarity opposite to the first charge polarity, and a fifth type of particle having a second charge polarity. The magnitudes of the first, second, and third charges may differ from each other. The charge magnitude of the third type of particle may be higher than the charge magnitude of the first type of particle, which may be higher than the charge magnitude of the second type of particle. The charge of the fourth type of particle may be higher than that of the fifth type of charged particle. In one example, the first type of particle is cyan, the second type of particle is magenta, the third type of particle is black, the fourth type of particle is yellow, and the fifth type of particle is white.

[0080] Sealing film from an aqueous sealing composition

[0081] A sealing film that seals the microcell openings of an electro-optical display must provide a barrier to the electrophoretic medium to prevent non-polar fluids from being removed from multiple microcells. Additionally, the sealing film must not have a negative impact on the electro-optical performance of the device.

[0082] One of the important characteristics of a sealing film is its electrical volume resistivity. If the volume resistivity of the sealing film is too high, a significant voltage drop occurs within the film, requiring the electrode voltage to be increased to operate the device. Increasing the electrode voltage in this manner is undesirable because it increases the display's power consumption and may necessitate the use of more complex and expensive control circuits to handle the increased voltage. On the other hand, if the volume resistivity of the sealing film is too low, unwanted crosstalk between adjacent pixel electrodes is observed, resulting in image quality degradation (blooming). Furthermore, since volume resistivity generally increases sharply as temperature decreases, an excessively high volume resistivity of the sealing film negatively affects the low-temperature electro-optical performance of the display. The volume resistivity of the sealing film is 10 8 It may be greater than Ohm·cm. The sealing film is 3.5 x 10 7 to 10 12 Ohm.cm or 10 8 to 10 10 It can have a volume resistivity of Ohm·cm. The sealing film is 10 10 It can have a volume resistivity of ohm.cm or less.

[0083] In addition to blocking characteristics and volume resistivity, another important characteristic of sealing films is moisture absorption. If a sealing film absorbs a significant amount of moisture from the environment over time, the electro-optical performance of the device may degrade.

[0084] The sealing film may be manufactured from an aqueous sealing composition comprising: a water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer in an amount of 14% to 55% by weight based on the weight of the aqueous sealing composition excluding water; a polyurethane in an amount of 6% to 27% by weight based on the weight of the aqueous sealing composition excluding water; carbon black in an amount of 5% to 64% by weight based on the weight of the aqueous sealing composition excluding water; a water-soluble ether in an amount of 1.0% to 40% by weight based on the weight of the aqueous sealing composition excluding water; and water in an amount of 20% to 95% by weight based on the weight of the aqueous sealing composition.

[0085] The poly(vinyl alcohol) homopolymer has a degree of hydrolysis of 90% to 99.5%. The poly(vinyl alcohol-co-ethylene) copolymer has a degree of hydrolysis of 90% to 99.5% and an ethylene content of less than 10%. The degree of hydrolysis of the poly(vinyl alcohol) homopolymer and the poly(vinyl alcohol-co-ethylene) copolymer may be 92% to 99%, or 92% to 95%. The ethylene content of the poly(vinyl alcohol-co-ethylene) copolymer may be less than 9%, or less than 8.5%, or less than 8%. The degree of hydrolysis of the polyvinyl alcohol homopolymers and copolymers is routinely reported by the respective polymer manufacturers and represents the unit (molar) ratio of vinyl alcohol in the polymer to the total vinyl units. The other unit is generally vinyl acetate (ester). The ethylene content of the poly(vinyl alcohol-co-ethylene) copolymer is also reported by the manufacturer, which represents the ratio of the unit (moles) of ethylene in the polymer to other units. In this case, the other units are vinyl alcohol and vinyl acetate. The poly(vinyl alcohol) homopolymer and poly(vinyl alcohol-co-ethylene) copolymer of the aqueous sealing composition may have a weight average molecular weight of 1,000 to 1,000,000 daltons, or 10,000 to 500,000 daltons, or 20,000 to 400,000 daltons.

[0086] The content of the water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer in the aqueous sealing composition may be 14% to 53% by weight, or 25% to 50% by weight, or 30% to 48% by weight, or 33% to 46% by weight, based on the weight of the aqueous sealing composition excluding water.

[0087] Polyurethanes are generally manufactured through a medium-addition process involving diisocyanates. Non-limiting examples of polyurethanes include polyether polyurethanes, polyester polyurethanes, polycarbonate polyurethanes, polyether polyureas, polyureas, polyester polyureas, polyester polyureas, polyisocyanates (e.g., polyurethanes containing isocyanate bonds), and polycarbodiimides (e.g., polyurethanes containing carbodiimide bonds). Generally, polyurethanes contain urethane groups. The polyurethanes used in the aqueous sealing compositions and sealing films described herein may be manufactured using methods known to those skilled in the art. The polyurethanes in the aqueous sealing compositions of the present invention are polyester polyurethanes, polycarbonate polyurethanes, and mixtures thereof. The polyurethane of the aqueous sealing composition may have a weight average molecular weight of 1,000 to 2,000,000 daltons, or 10,000 to 300,000 daltons, or 15,000 to 200,000 daltons. The polyurethane may be added to the aqueous sealing composition as an aqueous solution, an aqueous dispersion, an aqueous emulsion, or a latex.

[0088] The content of polyurethane in the aqueous sealing composition may be 7% to 27% by weight, or 9% to 24% by weight, or 11% to 22% by weight, or 12% to 20% by weight, based on the weight of the aqueous sealing composition excluding water.

[0089] The aqueous sealing composition may contain 0.1% to 8% by weight of a crosslinking agent (or crosslinking agent as another name), based on the weight of the aqueous sealing composition excluding water. During the curing of the aqueous sealing composition to manufacture a sealing film, the crosslinking agent forms chemical bonds between the polyurethane of the aqueous sealing composition and potentially the polymer molecules of the microcells, thereby increasing the adhesion between the sealing film and the microcells. It is preferable that the crosslinking agent be soluble or dispersed in the aqueous carrier of the aqueous sealing composition. The crosslinking agent may be a monomer, an oligomer, or a polymer. Examples of crosslinking agents include polyisocyanates, polycarbodiimides, polyaziridines, silane coupling agents, boron / titanium / zirconium-based crosslinking agents, or melamine formaldehyde. Polycarbodiimide crosslinking agents react under acidic pH conditions. It is preferable that the crosslinking agent be free of sulfosuccinate surfactants. The content of the crosslinking agent in the aqueous sealing composition may be 0.1% to 5% by weight, or 0.2% to 4% by weight, or 0.3% to 3.5% by weight, or 0.5% to 3% by weight, or 0.8% to 2.6% by weight, based on the weight of the aqueous sealing composition excluding water.

[0090] The inventors of the present invention have discovered that an aqueous sealing composition comprising a combination of a water-soluble poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer and a polyurethane can form a sealing film having excellent performance with an interfacial tension of less than 2 mN / m between the water-soluble poly(vinyl alcohol) polymer or the poly(vinyl alcohol-co-ethylene) copolymer and the polyurethane.

[0091] In addition, through extensive experimental work, excellent performance was observed in aqueous sealing compositions containing a combination of water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer and polyurethane, and it was revealed that the surface energy of the polar component of the polyurethane is 10 to 20 mN / m.

[0092] The aqueous sealing composition may also include a conductive filler in an amount of 5% to 64% by weight based on the weight of the aqueous sealing composition excluding water. The filler of the aqueous sealing composition may be selected from the group consisting of carbon black, graphene, graphite, and carbon nanotubes. The filler reduces the volume resistivity of the sealing film but may also affect other properties of the layer, such as surface energy. To be effective as a filler, carbon black must have excellent dispersibility in the aqueous sealing composition. The content of conductive carbon black in the aqueous sealing composition may be 10% to 55% by weight, or 20% to 50% by weight, or 25% to 45% by weight, or 30% to 40% by weight of the aqueous sealing composition.

[0093] The oil adsorption value of carbon black used in aqueous sealing compositions can be 100 cm³ or less per 100 mg of carbon black. Oil adsorption values ​​are generally reported by carbon black manufacturers in OANs, measured using methods according to ASTM 2414. This indicates the structure and degree of aggregation of the carbon black particles. In other words, a higher OAN implies a higher structure of carbon black particles (interconnected and having branched structures) and / or a higher degree of particle aggregation. More structured / aggregated carbon black can generally provide higher conductivity to sealing films, but conductivity can vary depending on the dispersibility of the filler, and a higher OAN indicates that the carbon black may be more difficult to disperse. For carbon black fillers in aqueous sealing compositions, it may be desirable for the average diameter of the primary particles to be greater than 30 nm. This is another physical characteristic of the carbon black grade that carbon black manufacturers can report. Primary particles can be measured using an electron microscope. Generally, carbon black with a very small average diameter of primary particles is difficult to disperse. The total surface area of ​​carbon black may be less than 80 m² / g, less than 75 m² / g, or less than 70 m² / g. This is another common physical property routinely reported by carbon black manufacturers. This is measured using the nitrogen adsorption method according to ASTM D 6556. The volume resistivity of carbon black may be higher than 0.1 Ohm·cm, which is measured in powder form at a pressure of 40 MPa using the ASTM D 2663 method.

[0094] The total surface energy of the conductive carbon black in the aqueous sealing composition may be higher than 40 mN / m or higher than 55 mN / m when measured by the washburn method using hexane as the test solution. The total surface energy of the conductive carbon black in the aqueous sealing composition may be 40 mN / m to 80 mN / m, or 40 mN / m to 70 mN / m, or 40 mN / m to 65 mN / m. The dispersed component of the surface energy of the conductive carbon black may be higher than 15 mN / m when measured by the washburn method using hexane as the test solution. The dispersed component of the conductive filler may be 15 mN / m to 40 mN / m, or 15 mN / m to 30 mN / m.

[0095] The aqueous sealing composition comprises 1.0% to 40% by weight of water-soluble ether based on the weight of the aqueous sealing composition excluding water. The aqueous sealing composition may comprise 1.5% to 35% by weight, or 2.0% to 30% by weight, or 2.5% to 25% by weight, or 4.0% to 22% by weight, or 5.0% to 20% by weight of water-soluble ether based on the weight of the aqueous sealing composition excluding water. The content of water-soluble ether in the aqueous sealing composition may be higher than 1.7 wt%, higher than 2 wt%, higher than 3 wt%, higher than 4 wt%, higher than 5 wt%, higher than 6 wt%, higher than 7 wt%, higher than 8 wt%, higher than 10 wt%, higher than 12 wt%, or higher than 15 wt% based on the weight of the aqueous sealing composition excluding water. The content of water-soluble ether in the aqueous sealing composition may be lower than 40 wt%, lower than 30 wt%, or lower than 25 wt% based on the weight of the aqueous sealing composition excluding water.

[0096] The water-soluble ether has a weight-average molecular weight of 75 to 5,000 daltons. The water-soluble ether may have a weight-average molecular weight of 85 to 3,000 daltons, or 90 to 1,000 daltons, or 90 to 500 daltons, or 90 to 300 daltons. The water-soluble ether may have a weight-average molecular weight higher than 75, higher than 90, higher than 100, or higher than 200. The water-soluble ether may have a weight-average molecular weight lower than 5,000, lower than 3,000, lower than 1,000, lower than 500, lower than 300, lower than 200, or lower than 150.

[0097] Water-soluble ethers are polar compounds that are soluble in water and polar organic solvents. Water-soluble ethers can be represented by the following chemical formulas I, II, or III.

[0098]

[0099]

[0100] The value of n is 1 to 145. The value of n may be 1 to 100, or 1 to 50, or 1 to 20, or 1 to 10, or 1 to 5, or 1 to 4, or 1 to 3, or 1 to 2. R1 is hydrogen, methyl, or ethyl group, and R2, R3, R4, R5, R6, and R7 are independently selected from the group consisting of hydrogen, linear or branched alkyl groups comprising 1 to 6 carbon atoms, phenyl, and benzyl groups. Formula I comprises at least one ether functional group. Formula II comprises at least one ether functional group. Formula III comprises at least one ether functional group.

[0101] Water-soluble ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol monoisopropyl ether, ethylene glycol n-monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol mono-t-butyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol diisopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol monoisopropyl ether, diethylene glycol n-monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol mono-t-butyl ether, and diethylene Glycol monobenzyl ether, diethylene glycol monophenyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol di-n-propyl ether, diethylene glycol diisopropyl ether, diethylene glycol di-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol mono-n-propyl ether, triethylene glycol monoisopropyl ether, triethylene glycol n-monobutyl ether, triethylene glycol monoisobutyl ether, triethylene glycol mono-t-butyl ether, triethylene glycol monobenzyl ether, triethylene glycol monophenyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol di-n-propyl ether, triethylene glycol diisopropyl ether, tetraethylene Glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monophenyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether, polyethylene glycol monophenyl ether,Propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol monoisopropyl ether, propylene glycol mono-n-butyl ether, propylene glycol monoisobutyl ether, propylene glycol monophenyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol monoisopropyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol monoisobutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol diisopropyl ether, tripropylene glycol monomethyl ether, tripropylene glycol It may be selected from the group consisting of monoethyl ether, tripropylene glycol mono-n-propyl ether, tripropylene glycol monoisopropyl ether, tripropylene glycol mono-n-butyl ether, tripropylene glycol monoisobutyl ether, or mixtures thereof.

[0102] The aqueous sealing composition may also contain a rheology modifier in an amount of 0.05 wt% to 10 wt%, or 0.05 wt% to 5 wt%, or 0.1 wt% to 3 wt%, based on the weight of the aqueous sealing composition excluding water. The rheology modifier increases the stability of the aqueous sealing composition during storage. It also promotes film formation, improves sealing stability, and provides other functions. Examples of this include associative thickeners, alkali-expanding acrylic emulsions, and other polymeric thickeners. The aqueous sealing composition may be shear-thinning, that is, its viscosity decreases at high shear. For example, the rheology profile of the aqueous sealing composition at a shear rate of 10 -4 Viscosity and shear rate at 1 / s 10 2It may indicate that the viscosity between the viscosity at 1 / s is reduced by 5 to 10,000 times. The sealing film may also include a rheology modifier in an amount of 0.05 wt% to 10 wt%, or 0.05 wt% to 5 wt%, or 0.1 wt% to 3 wt% based on the weight of the sealing film.

[0103] The aqueous sealing composition may also include a wetting agent, also known as a surfactant. Non-limiting examples of wetting agents include FC surfactants from 3M Company, Zonyl fluorosurfactants from DuPont, fluoroacrylates, fluoromethacrylates, fluorosubstituted long-chain alcohols, perfluorosubstituted long-chain carboxylic acids and their derivatives, and Silwet silicone surfactants from OSi, Greenwich, Connecticut, USA. The wetting agent can increase the affinity between the sealing film and the microcells, improve the interfacial area between the microcells, improve the adhesion between the sealing film and the microcells, and provide a more flexible coating process. The content of the wetting agent in the aqueous sealing composition may be 0.01% to 3.0% by weight, or 0.04% to 2.0% by weight, or 0.06% to 1.0% by weight, or 0.07% to 0.8% by weight, based on the weight of the aqueous sealing composition excluding water. The sealing film may include a wetting agent. The content of the wetting agent in the sealing film may be 0.01% to 3.0% by weight, or 0.04% to 2.0% by weight, or 0.06% to 1.0% by weight, or 0.07% to 0.8% by weight, based on the weight of the sealing film.

[0104] The aqueous sealing composition may contain 20% to 95% by weight, or 50% to 94% by weight, or 70% to 92% by weight, or 75% to 90% by weight, or 80% to 88% by weight of water based on the weight of the aqueous sealing composition.

[0105] The aqueous sealing composition may also include a pH adjuster. The pH adjuster is added to the aqueous sealing composition to adjust the pH to a value of 6.5 to 8.5. Examples of pH adjusters include ammonium hydroxide, but various acids and bases may be used. The pH adjuster can increase the pH of the aqueous sealing composition to reduce the crosslinking rate of the aqueous sealing composition before use, and can also improve the efficacy of the rheology modifier by providing optimal pH conditions for the modifier to interact with the particles of the aqueous sealing composition. The pH adjuster may be used in an amount of 0.2% to 1% by weight based on the weight of the aqueous sealing composition excluding water.

[0106] An aqueous sealing composition can be used to form a sealing film by applying the aqueous sealing composition and drying or curing the aqueous sealing composition. The sealing film may contain most of the components of the aqueous sealing composition. If the aqueous composition contains a crosslinking agent, the crosslinking agent is incorporated into the polyurethane polymer of the sealing film during curing. Additionally, the water in the sealing composition evaporates during the drying or curing of the aqueous sealing composition for the manufacture of the sealing film. According to experimental data, about 37 weight percent of the initially added water-soluble ether also evaporates during drying or curing, and it was found that only about 63 weight percent of the initially added water-soluble ether content of the aqueous sealing composition remains in the sealing film. If there is residual or absorbed water or moisture in the sealing film, the disclosed content of the components of the sealing film is calculated as a weight percent of the components based on the weight of the aqueous sealing composition excluding the residual or absorbed water, unless otherwise specified.

[0107] The sealing film comprises a water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer in an amount of 15% to 60% by weight based on the weight of the sealing film, wherein the poly(vinyl alcohol) homopolymer has a degree of hydrolysis of 90% to 99.5% and the poly(vinyl alcohol-co-ethylene) copolymer has a degree of hydrolysis of 90% to 99.5% and an ethylene content of less than 10%. The sealing film also comprises a polyurethane in an amount of 7% to 29% by weight based on the weight of the sealing film, a carbon black in an amount of 5% to 70% by weight based on the weight of the sealing film, and a water-soluble ether in an amount of 0.5% to 25% by weight based on the weight of the sealing film. The water-soluble ether may have a molecular weight of 90 to 5,000 daltons. The water-soluble ether may optionally include hydroxyl groups.

[0108] The physical and chemical properties of the components of various classes of sealing films have been described in detail above.

[0109] The content of the water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer in the sealing film may be 16% to 55% by weight, or 28% to 52% by weight, or 33% to 50% by weight, or 35% to 48% by weight, based on the weight of the sealing film.

[0110] The content of polyurethane in the sealing film may be 8% to 29% by weight, or 10% to 26% by weight, or 12% to 24% by weight, or 14% to 22% by weight, based on the weight of the sealing film.

[0111] The sealing film may contain conductive carbon black in an amount of 11% to 60% by weight, or 24% to 55% by weight, or 29% to 50% by weight, or 30% to 45% by weight, based on the weight of the sealing film.

[0112] The sealing film comprises a water-soluble ether in an amount of 0.5% to 25% by weight based on the weight of the sealing film. The sealing film may comprise a water-soluble ether in an amount of 0.8% to 20% by weight, or 1.0% to 18% by weight, or 1.2% to 20% by weight, or 1.5% to 18% by weight, or 2.0% to 16% by weight based on the weight of the sealing film. The content of the water-soluble ether in the sealing film may be higher than 0.5% by weight, higher than 0.6% by weight, higher than 0.7% by weight, higher than 0.8% by weight, higher than 0.9% by weight, higher than 1% by weight, higher than 1.5% by weight, higher than 2.0% by weight, higher than 3.0% by weight, or higher than 4% by weight based on the weight of the sealing film. The content of water-soluble ether in the sealing film may be lower than 25 wt%, lower than 20 wt%, lower than 18 wt%, lower than 15 wt%, lower than 12 wt%, or lower than 10 wt% based on the weight of the sealing film.

[0113] A sealing film prepared by an aqueous sealing composition can be used to seal microcells of an electro-optical device. The electro-optical device comprises a conductive layer, a microcell layer comprising a plurality of microcells, wherein each microcell comprises an opening, each microcell comprises an electrophoretic medium, and the electrophoretic medium comprises charged particles among non-polar carriers, a sealing film extending across the openings of each microcell, an adhesive layer, and an electrode layer.

[0114] Generally, the sealing film of an electro-optical device plays a critical role in display performance. If the blocking properties of the sealing film deteriorate, non-polar fluids of the electrophoretic medium leak out from the electro-optical material layer over time, severely degrading the electro-optical performance of the display. It has been observed that increasing the content of poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer in the sealing film improves blocking properties. However, sealing films with a high content of poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer increase moisture absorption, which is also undesirable.

[0115] The inventors of the present invention have surprisingly discovered that optimal electro-optical performance in terms of color gamut can be achieved when the sealing film comprises a combination of a poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer, polyurethane, conductive carbon black, and a water-soluble ether with a molecular weight of 75 to 5,000 daltons. It is believed that the addition of a water-soluble ether to an aqueous sealing composition and a sealing film reduces the electrical resistance of one or both of the interfaces of the layers adjacent to the sealing film, such as the sealing film-adhesive interface and the sealing film-electrophoretic medium interface. This reduction in electrical resistance at these interfaces was experimentally demonstrated through volume resistivity measurements and electrical impedance spectroscopy experiments, as shown in the Examples section. Importantly, the electrical resistance at these interfaces did not affect the electrical conductivity of the sealing film itself. Indeed, as the data indicate, the sealing film of the present invention has a higher volume resistivity than a control film that does not contain a water-soluble ether. As mentioned above, the high volume resistivity of the sealing film contributes to reducing blooming, a well-known phenomenon in the field of electro-optics.

[0116] Improved performance is also observed when a combination of a poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer and a polyurethane is used, wherein the interfacial tension between the poly(vinyl alcohol) polymer or the poly(vinyl alcohol-co-ethylene) copolymer and the polyurethane is less than 2 mN / m. Furthermore, the inventors of the present invention have surprisingly discovered that optimal performance is observed even when a combination of a poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer and a polyurethane is used, wherein the surface energy of the polar component of the polyurethane is 10 to 20 mN / m.

[0117] These and other aspects of the invention will be further understood by considering the following examples, which are intended to illustrate specific embodiments of the invention but are not intended to limit the scope of the invention as defined in the claims.

[0118] Examples

[0119] Evaluation method of sealing film

[0120] A. Example of preparation of an aqueous sealing composition

[0121] A1. Example of carbon black dispersion preparation. An aqueous solution of a poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer was prepared to contain 20% by weight of the polymer based on the solution volume. In one example, the polymer is a poly(vinyl alcohol-co-ethylene) copolymer (Exceval TMRS-1717, supplied by Kuraray). That is, 200 g of polymer was contained in the solution per liter of solution. Carbon black powder was mixed with an aqueous solution of poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer. In one example, an aqueous solution containing 106 g of poly(vinyl alcohol-co-ethylene) copolymer was mixed with 162 g of carbon black (Nerox® 3500, supplied by Orion Engineered Carbon). The dispersion was mixed in an overhead mixer (Hei-Torque Value 200) at 300 rpm for 30 minutes. Then, the dispersion was recirculated at 100% amplitude for 3 hours and 23 minutes in a 1 Q1375 Flocell Sonicator, where the jacket of the sonicator was cooled using cold water at 10°C. The dispersion was continuously stirred until it was used to prepare a sealing composition.

[0122] A2. Example of preparation of an aqueous sealing composition. In a container, an aqueous polyurethane dispersion was combined with a wetting agent and an aqueous solution of a poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer. In one example, 194 g of a 35 wt% aqueous polyurethane dispersion (L3838 aqueous dispersion, supplied by Hauthaway) was mixed with 372 g of an aqueous solution of a poly(vinyl alcohol-co-ethylene) copolymer (containing 20 wt% copolymer by solution volume). In this example, the poly(vinyl alcohol-co-ethylene) copolymer was Exceval supplied by Kuraray TMIt was RS-1717. The mixture was mixed at 90 rpm for 10 minutes using a Hei-Torque Value 200 overhead mixer. Then, mixing continued at 90 rpm while adding an appropriate amount of dipropylene glycol dimethyl ether (45 g in one example) for 5 minutes. The resulting mixture was further mixed at 90 rpm for 10 minutes, and an appropriate amount of crosslinking agent was added. The mixture was further mixed at 90 rpm for 60 minutes. An appropriate amount of the carbon black dispersion prepared in A1 (1.39 L in one example) was added, and the resulting dispersion was mixed at 500 rpm for 60 minutes. Then, the pH was adjusted to 6.5-8.5 using ammonium hydroxide, and the dispersion was further mixed for 30 minutes. An appropriate amount of rheology modifier was added dropwise to the dispersion, and mixing continued for another 60 minutes. Next, the dispersion was degassed for 5 days under reduced pressure (25 mmHg). The resulting aqueous sealing composition was used to manufacture a sealing film for the device within 7 days of the preparation of the sealing composition.

[0123] B1. Example of manufacturing a sealing film using a draw-down method

[0124] The sealing composition prepared in A2 above was coated onto the indium tin oxide (ITO) side of an ITO-PET film using a Gardco drawdown coater. A 15-mil gap and 8-path square applicator was used. The drawdown speed was set to 2 m / min with a target dry film thickness of 30 + / - 2 µm. The coating was dried in a 100°C oven for 15 minutes. The dried film was conditioned at 25°C and 55% RH for 24 hours.

[0125] B2. Example of manufacturing a sealing film using a roll-to-roll coating line

[0126] The sealing composition prepared in A2 above was coated onto the indium tin oxide (ITO) side of an ITO-PET thin film at a speed of 9 ft / min and a dry thickness of 30 μm using a slot die of a roll-to-roll coating line. The film was moved through a convection oven consisting of four heating zones at a speed of 9 ft / min. The length of each heating zone was 5 feet. The first zone was set to a temperature of 80°C, and the remaining heating zones were set to a temperature of 100°C. After the dried sealing film on the ITO-PET passed through the drying oven, the film was cut into three sections, each approximately 24 to 30 inches in length, and placed in a cleanroom controlled environment at a temperature of 25°C and 55% relative humidity (RH).

[0127] C. Measurement of Volume Resistivity - TCBC Method

[0128] The volume resistivity of a sealing film manufactured according to Method B2 (Method for Manufacturing a Sealing Film) described above was evaluated. The "TCBC Method" was used to describe the transient current background current method for measuring volume resistivity. For volume resistivity measurement, Labview 2014 software, the TCBC waveform program, an NI USB 6211 multifunction device, and a Model 603 power amplifier were used. Using this equipment, the volume resistivity of an electrode-laminated sample can be measured by applying a waveform at a preset voltage and calculating the resistance by measuring the output current. This method includes (a) the manufacture of a sealing film according to B2 of the "Method for Manufacturing a Sealing Film" disclosed above, (b) a method of laminating the sealing film onto a conductive adhesive and a graphite backplane, and (c) a test method using the waveform program and settings. The thickness of the film was measured using a Mitutoyo Model S112EXB thickness gauge. After the lamination process, the sample was conditioned at 25°C / 55% RH for 10 days prior to testing. Next, the volume resistivity was calculated using the following equation r = R / t, where r is the resistivity, R is the resistance, and t is the thickness, using the indicated resistance and the measured thickness.

[0129] Panels of each seal coated on ITO-PET were collected one by one from the roll-to-roll coating line described in Method B2 above. The seals were cut into 12-inch length pieces. As shown in the image in Fig. 8A, the 12-inch length pieces were cut to a width of 4.5 inches. The excess ITO at the edges was not trimmed.

[0130] Graphite Backplane Preparation: For the test, one graphite backplane (5 pixels) was collected for each sealing film. One of the pixels from the end was cut off, leaving only 4 pixels. As shown in the image in Fig. 8B, the top and side edges were trimmed (where the pixel lines extend). The other edge was not trimmed.

[0131] KA2 Film Preparation: A long roll of certified 6 µm thick KA2 conductive adhesive film was collected for use in the test. The KA2 film was cut into 3-inch wide pieces. As shown in the image in Fig. 8C, the 3-inch wide pieces were cut to a length of 10 inches. Only one side was cut so that the release liner protrusion remained on the other side.

[0132] TCBC Sample Lamination: A 6 µm thick conductive adhesive KA2 was laminated onto a dried sealing film using a hot-roll laminator. For this lamination, the bottom plate and top roller of the laminator were set to 80°C, and the lamination speed was set to 17 mm / sec. A cut KA2 film was taped to the cut sealing film so that the protective sheet of KA2 touched the sealing film. The bottom and right edges of the KA2 film were aligned with the bottom and right edges of the sealing film. The top of the KA2 film was taped to the sealing film. The top of the sealing film was taped to the laminator plate so that its top edge was positioned just below the center of the roller. While holding the top sheet with KA2, the protective sheet of KA2 was gently removed. While continuing to hold KA2, lamination began, allowing the roller to slowly press KA2 onto the sealing film. After lamination was complete, the tape was removed, and the layer was peeled off from KA2. A graphite backplane was carefully placed on top of KA2. The electrode was placed in the center of the KA2. The sample was stacked, and the final preparation process is illustrated in FIG. 8D. The final TCBC sample (800) included an ITO / PET conductive film (801), a sealing film (802), a KA2 adhesive (803), and a graphite backplane (804). One area of ​​the conductive film (801) and a first test point of the graphite backplane (804) were electrically connected via a voltage source. Then, the sample was conditioned at 25°C / 55% RH for 10 days to ensure sufficient humidification.

[0133] Testing of TCBC Samples: After conditioning for 10 days at 25°C / 55% RH, the samples were ready for testing. Additionally, to minimize variability due to temperature or relative humidity, the samples were tested in a controlled environment chamber set to 25°C / 55% RH. To run the TCBC test, the process began by opening the corresponding software. The seal was peeled back 1 / 2 inch from the side of the sample to expose the ITO-PET surface. On a computer running Windows 10, the TCBC Resistance Program was opened using Labview 2014 and the TCBC waveform program. The contact area of ​​the single pixel region used to measure the sample's resistivity was set to 25 cm². The range was set to 200 μA (matching the Model 6487 electric meter). One alligator clip was connected to the ITO-PET of the sealed resistivity sample. Another alligator clamp was connected to the first test pixel of the graphite backplane. Once the connections were established, the test was started. During the test, the following waveform, pulsed at a magnitude of 15 volts for a total time of 26,699 ms as shown in Fig. 8E, was executed. During this time, the software program and the electric instrument measured the current over time. Then, based on Ohm's law, the software calculated the resistance of the sample from the measured current and the input voltage: R = (V / I),

[0134] In the equation, V is the input voltage, I is the measured current, and R is the resistance. To calculate the final volume resistivity of the sample, use the following equation: r = R / t,

[0135] In the formula, R is the resistance obtained from the test, and t is the thickness of the sealing film measured using a thickness gauge to complete the test.

[0136] D. Electric Impedance Spectroscopy (EIS):Electric impedance spectroscopy (EIS) was used to understand how the presence of a water-soluble ether (dipropylene glycol dimethyl ether) in the sealing film affects the electro-optical performance without increasing the volume resistivity of the film. EIS measured the interfacial resistivity between the sealing film and the electrophoretic medium (containing a non-polar solvent and charged yellow pigment particles).

[0137] Using the EIS results, the distribution of relaxation time (DRT) was calculated. Figure 9 shows a graph of gamma values ​​versus relaxation time (tau) from EIS data for the sealing film of the present invention (containing water-soluble ether) and the control sealing film (not containing water-soluble ether) for two different electrophoretic media A and B. Different peaks of gamma values ​​at different relaxation times (tau) correlate with different parallel resistance and capacitor (RC) elements of the electro-optical device containing the sealing film in contact with the electrophoretic medium. Each peak is the average of the relaxation times for all RC elements with similar relaxation times in the electro-optical device. The gamma value for each relaxation time is the measured resistance of the corresponding RC element. In most cases, the relaxation time (tau) at 4 1 / s corresponds to the RC element at the sealing film-electrophoretic medium interface. As can be seen in both electrophoretic media A and B, in the case of the sealing film containing a water-soluble ether (dipropylene glycol dimethyl ether), the resistance at the interface between the sealing film and the electrophoretic medium is lower. As shown in the data in the example table, the lower the interfacial resistance, the better the electro-optical performance.

[0138] E. Measurement of film surface energy

[0139] The surface energy of the prepared sealing film (as described in B1 above) was measured using a drop shape analyzer supplied by Kruss GmbH. Using a needle-equipped syringe, a 2.6 μL drop of deionized water was placed on the top surface of the sealing film, and the contact angle between the liquid (water) and the sealing film was measured. The measurement was repeated by replacing the drop with a diiodomethane drop. The surface energy of the film was calculated by performing contact measurements using these two liquids, which have known surface energies. Contact angle measurements were repeated three times for each liquid (water and diiodomethane). At 5, 30, and 55 seconds after the drop was placed on the sample film, the contact angle between the liquid and the top surface of the sealing film was measured using a high-resolution camera. Subsequently, the total surface energy and its polarity and dispersion components were calculated for each data point using the Owens, Wendt, Rabel, and Kaelble (OWRK) method. The reported surface energy is the average value of 9 data points (3 droplets x 3 time scales).

[0140] F. Manufacturing of Electro-Optical Devices

[0141] An electro-optical device was fabricated by filling a mixture of electrically charged pigment particles (white, cyan, magenta, and yellow) in multiple microcells with Isopar E. The white and yellow particles were negatively charged, and the cyan and magenta particles were positively charged. Then, an aqueous sealing composition was coated on the openings of the microcells as described in B above. The device described in FIG. 10 was constructed. The electro-optical device (1000) was composed of a protective film (1001), an optically transparent first adhesive layer (1002), a substrate (1003), a light-transmitting conductive layer (1004), a primer layer (1005), a microcell layer (1006), a sealing film (1007), a second adhesive layer (1008), an ITO electrode layer (1009), and a glass layer (1010) in that order. The source of the electric field (1011) electrically connected the light-transmitting conductive layer (1004) to the ITO electrode layer (1009). A waveform was applied through this source to drive the desired optical state. The approximate thickness of the first light-transmitting layer (1002) was 25 μm. The approximate thickness of the substrate (903) was 100 μm. The approximate thickness of the primary layer (1005) was 0.4 μm. The microcell layer (1006) consisted of a plurality of microcells. The approximate bottom thickness of each microcell was 0.4 μm, and the approximate height was 10 μm. The sealing film (807) had a thickness of approximately 10 μm, and the second adhesive layer had a thickness of approximately 4.5 μm.

[0142] G. Color gamut measurement

[0143] The electro-optical device manufactured by Method F was electrically driven to generate eight optical states. The electro-optical device was processed using a sequence of electrical pulses (such a sequence is referred to as a "waveform"). In the following description, the voltage used in the waveform is the voltage supplied to the back electrode of the display, assuming that the electrode on the front (visible) surface of the display is the common electrode of all pixels and is connected to ground. The test waveform includes a series of "dipoles" as illustrated in FIG. 11. Each dipole consists of two monopoles, and each monopole is a pulse of length t and magnitude V. The two monopoles of each dipole have opposite polarities.

[0144] The voltages used for the test waveforms were + / -24V, + / -18V, + / -15V, and + / -10V. Time was discretized into units of 11.74 ms, referred to as "frames." Each frame corresponds to one scan of a thin-film transistor array backplane refreshed at a frequency of 85 Hz, but in the described test, the backplane was segmented and driven directly.

[0145] To evaluate the electro-optical performance of the device, two types of test waveforms were used. The length of the waveform used in the first test was 18 frames, and the length of the waveform used in the second test was 42 frames. In each case, the waveform was filled with an equal number of dipoles corresponding to the allowed number of frames. This is shown in Tables 1 and 2, corresponding to the 18-frame and 42-frame waveform types, respectively.

[0146]

[0147]

[0148] The length of the second monopole is the length of the dipole minus the length of the first monopole. "First" and "second" do not necessarily imply a specific temporal order of the monopoles constituting the dipole. Not all dipoles corresponding to this rule were used. To test more reasonable lengths, only waveforms where (V2*t2) / (V1*t1) < 2 were used.

[0149] Each waveform was preceded by a DC balancing pulse (having impulses the same as and opposite to the specific test waveform) and a process of resetting the display to a white state. Each waveform ended with a 3-second ground cycle.

[0150] After 3 seconds of grounding, the display's color states (measured in CIELab L*, a*, and b* units) were recorded. The display's color gamut was measured by calculating the volume of the convex hull containing all color states generated by a series of test waveforms. The eight generated color states were red, green, blue, yellow, cyan, magenta, white, and black (R, G, B, Y, C, M, W, and K). The color gamut was DE 3 It was reported in units. The wider the color gamut, that is, the wider the spatial area, the better the electro-optical performance of the electro-optical device.

[0151] H. Measurement of interfacial tension of polymers

[0152] The interfacial tension between Polymer 1 and Polymer 2 for a specific combination of polymers was calculated from the surface tension values ​​(determined via the method described in H above). The calculation of the interfacial tension between the two components was performed using the surface energy values ​​of each component and the following geometric equation:

[0153]

[0154] In the formula, σ AB is the interfacial tension between polymers A and B, and σ A is the total surface energy of polymer A, and σ B is the total surface energy of polymer B, and σ A D and σ A D are the dispersion components of the surface energy of polymers A and B, respectively, and σ A P and σ A P is a polar component of the surface.

[0155] Similarly, the interfacial tension between the sealing film and the adhesive layer can be measured. An adhesive layer standard comprising a polyurethane formed from an aqueous dispersion of a water-dispersible polyurethane.

[0156] I. Evaluation of Barrier Characteristics of Sealing Films for Non-Polar Fluids

[0157] An aqueous dispersion was prepared by mixing 10 g of poly(vinyl alcohol) homopolymer or 10 g of poly(vinyl alcohol-co-ethylene) copolymer and 10 g of polyurethane in 100 mL of water. The dispersion was used as an aqueous polymer composition to form a sealing film of the device (1200) shown in FIG. 12. The sealing film was formed by the method described in B1 above. The device (1200) included, in order, a substrate (1203), a light-transmitting conductive layer (1204), a primer layer (1205), a microcell layer (1206), and a sealing film (1207). The microcell included an electrophoretic medium containing white, black, and red pigment particles in Isopar E. The device (1200) was stored at 70°C for at least 24 hours. After this period, the electro-optical device was inspected using an optical microscope to check for sagging of the sealing film due to the loss of non-polar fluid of the electrophoretic medium. If the distance between the bottom of the inspected microcavity of the sealing film and the lowest point on the bottom surface was less than 85% of the distance between the bottom of the microcavity of the sealing film and the highest point on the bottom surface in the same microcell, the aqueous polymer composition was marked as "failure" for blocking characteristics. Otherwise, that is, if the distance between the bottom of the inspected microcell of the sealing film and the lowest point was 85% or more of the distance between the bottom of the microcell of the sealing film and the highest point on the bottom surface in the inspected microcell, the sealing of the aqueous polymer composition was marked as "pass" for blocking characteristics. For example, the aqueous polymer composition used to manufacture the electro-optical device shown in Fig. 13C was marked as "passed" because the ratio of h2:h1 was 1 (no sagging), whereas the aqueous polymer composition used to manufacture the electro-optical device shown in Fig. 13D was marked as "failure" because the ratio of h2:h1 was 35% (sagging level of more than 85%).The evaluation of blocking characteristics may also be performed qualitatively by observing the prepared electro-optical device from the field of view surface of the device using an optical microscope. A device containing a severely sagging sealing film has a significantly different appearance (non-uniform vs. uniform surface) compared to a device containing a sealing film with excellent blocking characteristics for non-polar fluids. For example, a microcell ("pass") having an aqueous polymer composition corresponding to the sealing film of FIG. 13C appears uniform as shown in FIG. 13A, whereas a microcell ("failure") having an aqueous polymer composition corresponding to the sealing film of FIG. 13D appears non-uniform as shown in FIG. 13B. Evaluations of various combinations of (1) poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer and (2) polyurethane are shown in Table 10. Polymer 1 is a poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer, and polymer 2 is polyurethane. Detailed information on commercial materials of polymer 1 and polymer 2 can be found in Table 11.

[0158] J. Measurement of water-soluble ether content in sealing film

[0159] The content of water-soluble ether in the sealing film was determined by a combination of thermogravimetric analysis (TGA) and Karl Fischer (KF) moisture analysis. The sum of the amounts of water-soluble ether and moisture in the sealing film was determined by the thermogravimetric analysis method described below. The moisture content in the sealing film was measured using the Karl Fischer method at 150°C. Then, the content of water-soluble ether in the sealing film was calculated by subtracting the moisture content (KF) from the sum of the amounts of water-soluble ether and moisture (TGA). Thermogravimetric analysis involved (a) zeroing the weight of the sample holder, (b) placing the sample in the sample holder and weighing it, (c) equilibrating the sample at 30°C, (d) heating the sample to 105°C at a heating rate of 50°C / min, (e) holding the sample at 105°C for 10 minutes to evaporate moisture and other volatile substances to be removed from the sample, (f) heating the sample to 215°C at a rate of 50°C / min, (g) holding the sample at 215°C for 10 minutes to evaporate water-soluble ethers, and (h) heating the sample to 650°C at a rate of 20°C / min for complete decomposition of the sample. The sample was stored under nitrogen gas during the thermogravimetric analysis. The total amount of moisture and water-soluble ethers was obtained through weight loss of the sample from 40°C to 220°C using Trios software.

[0160] Evaluation results

[0161] Unless otherwise specified, the amounts of components included in the compositions disclosed in the table below are provided as weight percentages of the components based on the weight of the composition excluding water. In some compositions, the term QS (appropriate amount) is used to indicate the content of the water carrier. This means that the water content in the composition is the amount necessary to achieve 100% of the total composition, and is not more than that.

[0162] If there is residual or absorbed water or moisture in the sealing film, the disclosed content of the components of the sealing film is calculated as the weight percent of the components excluding the residual or absorbed water, unless otherwise specified.

[0163] Example compositions having numbers ending in the letter F correspond to sealing film compositions, while the remaining example compositions correspond to aqueous sealing compositions. Examples of sealing film compositions correspond to the same example number (including the suffix F) as the aqueous sealing composition used to manufacture the sealing film composition. Accordingly, Example 1F (sealing film composition) was prepared from Example 1 (aqueous sealing composition).

[0164] The content of water-soluble ether in the sealing film of Example 19F was determined to be 8.6% by weight based on the weight of the sealing film using the method described in J above. The content of water-soluble ether in other sealing film examples was calculated to be 63% of the total water-soluble ether in the aqueous sealing composition.

[0165]

[0166]

[0167]

[0168]

[0169] Tables 3A and 3B show that, unlike a control aqueous sealing composition not containing a water-soluble ether that forms a sealing film having a higher volume resistivity, an aqueous sealing composition containing a water-soluble ether such as dipropylene glycol dimethyl ether or tetraethylene glycol dimethyl ether forms a sealing film having a higher volume resistivity, 10 9 It demonstrates the formation of a sealing film having a volume resistivity (TCBC) lower than Ohm·cm. This can be seen by comparing Examples 1F-5F with Comparative Example 6F, and Examples 7F-8F with Comparative Example 9F.

[0170]

[0171]

[0172]

[0173]

[0174]

[0175]

[0176]

[0177]

[0178] Tables 4A, 4B, 5A, 5B, 4A, 6B, 7A, and 7B show that an aqueous sealing composition containing a water-soluble ether, such as dipropylene glycol dimethyl ether or tetraethylene glycol dimethyl ether, forms a sealing film having a larger color range than a control aqueous sealing composition that does not contain a water-soluble ether. This can be seen by comparing the embodiments of the present invention with the corresponding comparative examples. Improved electro-optical performance is consistently observed in the color range measured at different temperatures (0°C and 25°C).

[0179]

[0180]

[0181]

[0182]

[0183] Tables 8A, 8B, 9A, and 9B show that an aqueous sealing composition containing a water-soluble ether, such as dipropylene glycol dimethyl ether (Examples 18-19 and Example 21), forms a sealing film having an interfacial tension with an adhesive layer of less than 20 mN / m, unlike an aqueous sealing composition not containing a water-soluble ether (Comparative Example 20 and Comparative Example 22).

[0184] [1] Poly(vinyl alcohol-co-ethylene) copolymer; Exceval TMRS-1717, supplied by Kuraray;

[0185] [2] Polyurethane aqueous dispersion; L3838 aqueous dispersion, supplied as a 35% aqueous dispersion by Hauthaway;

[0186] [3] Carbon black; Nerox® 3500, supplied by Orion Engineered Carbon;

[0187] [4] Polycarbodiimide (multifunctional polycarbodiimide - aqueous solution); CARBODILITE® V-02-L2, supplied as a 40% aqueous solution by Nisshinbo Chemical;

[0188] [5] Hydrophobic modified alkaline expansive acrylic emulsion; Solthix TM A-100, supplied by Lubrizol;

[0189] [6] Siloxane polyalkylene oxide copolymer; Silwet® L-7607 copolymer, supplied by Momentive;

[0190] [7] Dipropylene glycol dimethyl ether; supplied by Proglyde® DMM, Dow Chemical;

[0191] [8] Tetraethylene glycol dimethyl ether, supplied by Sigma Aldrich (CAS 143-24-8).

[0192] Table 10 contains surface energy data for various polymer 1 species, which are water-soluble poly(vinyl alcohol) homopolymers or poly(vinyl alcohol-co-ethylene) copolymers, and polymer 2 species, which are polyurethanes. It also includes evaluations of the barrier properties of various layers and calculated interfaces of various polymer combinations. The method for preparing the corresponding polymer layer used for evaluating barrier properties is described in I above. The measurement of surface energy (according to the method described in E above) was performed by first preparing and conditioning a sealing film from the corresponding aqueous composition containing only one polymer. The interfacial tension for each polymer combination was calculated from the surface energy data and the calculation method described in H above.

[0193]

[0194]

[0195]

[0196]

[0197] The interfacial tension data of polymer 1 and polymer 2 in Table 10 shows that a sealing film comprising (a) a poly(vinyl alcohol) polymer or poly(vinyl alcohol-co-ethylene) copolymer with a degree of hydrolysis of 90% to 99.5% and an ethylene content of less than 10% among aqueous carriers, and (b) a polyurethane, wherein the interfacial tension between the two polymers (a) and (b) is less than 2 mN / m, forms a sealing film having excellent blocking properties for non-polar fluids.

[0198] The data in Table 10 also shows that a sealing film prepared from an aqueous sealing composition comprising (a) a poly(vinyl alcohol) polymer or poly(vinyl alcohol-co-ethylene) copolymer with a hydrolysis degree of 90% to 99.5% and an ethylene content of less than 10% and (b) a polyurethane, wherein the surface energy of the polar component of the polyurethane is 10 to 25 mN / m, forms a sealing film having excellent barrier properties against non-polar fluids.

[0199] Microscopic evaluation of sealing films prepared by four types of aqueous sealing compositions prepared by the method described in B1 above showed a correlation between the uniformity of the film and the interfacial tension between the two polymers. Microscopic images in Table 12 and Figure 14 show that lower interfacial tension provides a more uniform sealing film. The improved compatibility achieved by combinations of polymers with lower interfacial tension can explain the improved blocking properties of the corresponding layer.

[0200]

[0201] In addition, during the study, it was observed that an aqueous sealing composition containing more than 70% by weight of poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer, based on the weight of the aqueous sealing composition excluding water, formed a sealing film that absorbed a significant amount of moisture from the environment. This high moisture absorption negatively affects the electro-optical performance of the display.

Claims

Claim 1 A water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer having a content of 15% to 60% by weight based on the weight of the sealing film, wherein the water-soluble poly(vinyl alcohol) homopolymer has a degree of hydrolysis of 90% to 99.5% and the poly(vinyl alcohol-co-ethylene) copolymer has a degree of hydrolysis of 90% to 99.5% and an ethylene content of less than 10%; a polyurethane having a content of 7% to 29% by weight based on the weight of the sealing film; and carbon black having a content of 5% to 70% by weight based on the weight of the sealing film. A sealing film comprising a water-soluble ether having a molecular weight of 75 to 5,000 daltons and optionally including a hydroxyl group, wherein the water-soluble ether has a content of 0.5% to 25% by weight based on the weight of the sealing film. Claim 2 In claim 1, the sealing film has a total surface energy lower than 60 mN / m. Claim 3 A sealing film according to claim 1, wherein the interfacial tension between a water-soluble poly(vinyl alcohol) homopolymer or a poly(vinyl alcohol-co-ethylene) copolymer and a polyurethane is less than 2 mN / m. Claim 4 In claim 1, the oil adsorption value of the carbon black, measured using the OAN method according to ASTM 2414, is 100 cm per 100 mg. 3 Sealing film for Lee Ha-in. Claim 5 In claim 1, the carbon black is a sealing film with a total surface area of ​​less than 70 m² / g as measured using the nitrogen adsorption method according to ASTM D6556. Claim 6 In claim 1, the water-soluble ether is a sealing film represented by the following chemical formula I, chemical formula II, or chemical formula III: In the formula, n is 1 to 145; R1 is hydrogen, methyl or ethyl group; R2, R3, R4, R5, R6 and R7 are independently selected from the group consisting of hydrogen, linear or branched alkyl groups containing 1 to 6 carbon atoms, phenyl and benzyl groups; Formula I comprises at least one ether functional group; Formula II comprises at least one ether functional group; and Formula III comprises at least one ether functional group. Claim 7 In claim 6, n is a sealing film of 1 to 10. Claim 8 In claim 1, the water-soluble ether is ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol monoisopropyl ether, ethylene glycol n-monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol mono-t-butyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol diisopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol monoisopropyl ether, diethylene glycol n-monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol mono-t-butyl Ether, Diethylene glycol monobenzyl ether, Diethylene glycol monophenyl ether, Diethylene glycol dimethyl ether, Diethylene glycol diethyl ether, Diethylene glycol ethyl methyl ether, Diethylene glycol di-n-propyl ether, Diethylene glycol diisopropyl ether, Diethylene glycol di-n-butyl ether, Triethylene glycol monomethyl ether, Triethylene glycol monoethyl ether, Triethylene glycol mono-n-propyl ether, Triethylene glycol monoisopropyl ether, Triethylene glycol n-monobutyl ether, Triethylene glycol monoisobutyl ether, Triethylene glycol mono-t-butyl ether, Triethylene glycol monobenzyl ether, Triethylene glycol monophenyl ether, Triethylene glycol dimethyl ether, Triethylene glycol diethyl ether, Triethylene glycol di-n-propyl ether, Triethylene glycol diisopropyl Ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monophenyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether, polyethylene glycol monophenyl ether,Propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol monoisopropyl ether, propylene glycol mono-n-butyl ether, propylene glycol monoisobutyl ether, propylene glycol monophenyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol monoisopropyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol monoisobutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol diisopropyl ether, tripropylene glycol monomethyl ether, tripropylene glycol A sealing film selected from the group consisting of monoethyl ether, tripropylene glycol mono-n-propyl ether, tripropylene glycol monoisopropyl ether, tripropylene glycol mono-n-butyl ether, and tripropylene glycol monoisobutyl ether. Claim 9 A sealing film according to claim 1, further comprising an organic silicone wetting agent. Claim 10 In paragraph 1, the volume resistivity is 10 8 to 10 10 Sealing film with an Ohm.cm thickness. Claim 11 In paragraph 1, the polyurethane is a sealing film that is an ester polyurethane, a polycarbonate polyurethane, or a combination thereof. Claim 12 In claim 1, the polyurethane is a sealing film having a number average molecular weight of 1,000 to 2,000,000 daltons. Claim 13 In claim 1, the water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer is a sealing film having a number average molecular weight of 1,000 to 1,000,000 daltons. Claim 14 In claim 1, the water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer is a sealing film having a degree of hydrolysis of 92% to 99%. Claim 15 In claim 1, the poly(vinyl alcohol-co-ethylene) copolymer is a sealing film having an ethylene content of less than 9%. Claim 16 An electro-optical device comprising: a conductive layer; a microcell layer comprising a plurality of microcells, wherein each microcell comprises an opening, and each microcell comprises an electrophoretic medium, and the electrophoretic medium comprises charged particles among non-polar carriers; a sealing film according to claim 1, wherein the sealing film is a sealing film extending across the opening of each microcell; an adhesive layer; and an electrode layer. Claim 17 In claim 16, the electrophoretic medium comprises at least three types of charged pigment particles, and one type of charged particle has a color selected from the group consisting of blue, green, red, cyan, magenta, and yellow, an electro-optical device. Claim 18 A water-soluble poly(vinyl alcohol) homopolymer or poly(vinyl alcohol-co-ethylene) copolymer having a content of 14% to 55% by weight based on the weight of the aqueous sealing composition excluding water, wherein the water-soluble poly(vinyl alcohol) homopolymer has a degree of hydrolysis of 90% to 99.5% and the poly(vinyl alcohol-co-ethylene) copolymer has a degree of hydrolysis of 90% to 99.5% and an ethylene content of less than 10%; a polyurethane having a content of 6% to 27% by weight based on the weight of the aqueous sealing composition excluding water; carbon black having a content of 5% to 64% by weight based on the weight of the aqueous sealing composition excluding water; and a water-soluble ether having a content of 1.0% to 40% by weight based on the weight of the aqueous sealing composition excluding water, with a molecular weight of 75 to 5,000 A water-soluble ether that is a Dalton and optionally contains a hydroxyl group; and an aqueous sealing composition comprising water in an amount of 20% to 95% by weight based on the weight of the aqueous sealing composition. Claim 19 An aqueous sealing composition according to claim 18, further comprising a crosslinking agent in an amount of 0.1% to 8% by weight based on the weight of the aqueous sealing composition excluding water, wherein the crosslinking agent is a polyisocyanate, a polycarbodiimide, a polyfunctional aziridine, a silane coupling agent, a boron / titanium / zirconium-based crosslinking agent, or melamine formaldehyde. Claim 20 In claim 18, the aqueous sealing composition further comprises a rheology modifier in an amount of 0.05 wt% to 5 wt% based on the weight of the sealing film, and the aqueous sealing composition has a rheology profile, and the rheology profile has a shear rate 10 -4 Viscosity and shear rate at 1 / s 10 2 An aqueous sealing composition exhibiting a viscosity reduction of 5 to 10,000 times between the viscosity at 1 / s.

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