Electro-optic display with an electro-optic material layer having a binder comprising a polymer with a quaternary ammonium group and a method for manufacturing the same

Abstract

An electro-optic display comprising a layer of electro-optic material comprising an electrophoretic medium encapsulated in a plurality of microcapsules dispersed in an adhesive, and an efficient and robust method of manufacturing the electro-optic display. The adhesive for the electro-optic material layer comprises a polymer containing one or more quaternary ammonium functional groups in its molecular structure. The adhesive provides antimicrobial protection and is capable of improving electro-optic performance.

Description

(19) State Intellectual Property Office (12) Invention Patent Application (10) Application Publication Number (43) Application Publication Date (21) Application Number 202480061952.6 (22) Application Date 2024.10.22 (30) Priority Data 63 / 546376 2023.10.30 US (85) PCT International Application Entering National Phase Date 2026.03.26 (86) PCT International Application Application Data PCT / US2024 / 052327 2024.10.22 (87) PCT International Application Publication Data WO2025 / 096239 EN 2025.05.08 (71) Applicant Eink Company Address Massachusetts, USA (72) Inventor R. Casado S. Yegolov (74) Patent Agency Beijing Panhua Weiye Intellectual Property Agency Co., Ltd. 11280 Patent Attorney Guo Guangxun (51) Int.Cl. G02F 1 / 167 (2019.01) G02F 1 / 16757 (2019.01) G02F 1 / 1676 (2019.01) (54) Invention Title Electro-optic Display Having an Electro-optic Material Layer, the Electro-optic Material Layer Having an Adhesive and the Adhesive Containing a Polymer Having Quaternary Ammonium Groups Thereof and a Method for Manufacturing the Same (57) Abstract An electro-optic display comprising an electro-optic material layer and an efficient and robust method for manufacturing the electro-optic display, the electro-optic material layer comprising an electrophoretic medium encapsulated in a plurality of microcapsules dispersed in an adhesive. The adhesive of the electro-optic material layer comprises a polymer containing one or more quaternary ammonium functional groups in its molecular structure. The adhesive provides antimicrobial protection and is capable of improving electro-optic performance. Claims (2 pages), Description (12 pages), Drawings (4 pages), CN 121941953 A, 2026.04.28, CN 1 21 94 19 53 A 1. An electro-optic display, comprising, in sequence: a first electrode layer including a light-transmitting electrode; an electro-optic material layer comprising a plurality of microcapsules dispersed in an adhesive, each microcapsule comprising an electrophoretic medium comprising a plurality of charged pigment particles and a nonpolar liquid, the adhesive comprising a polymer containing one or more quaternary ammonium functional groups in its molecular structure; and a second electrode layer including a plurality of pixel electrodes. 2. The electro-optic display of claim 1, wherein the electro-optic material layer is substantially free of biocides. 3. The electro-optic display of claim 1 or claim 2, wherein the adhesive comprises poly(vinyl alcohol), the poly(vinyl alcohol) containing one or more quaternary ammonium functional groups in its molecular structure. 4. The electro-optic display of claim 3, wherein the poly(vinyl alcohol) has a weight-average molecular weight of 1,000 to 1,000,000 Daltons.5. The electro-optic display according to claim 3 or claim 4, wherein the poly(vinyl alcohol) is crosslinked. 6. The electro-optic display according to any one of claims 3 to 5, wherein for each vinyl alcohol unit of the polymer, the poly(vinyl alcohol) contains 0.03 to 0.4 quaternary ammonium functional groups. 7. The electro-optic display according to any one of claims 3 to 5, wherein for each vinyl alcohol unit of the polymer, the poly(vinyl alcohol) contains 0.05 to 0.2 quaternary ammonium functional groups. 8. The electro-optic display according to any one of claims 3 to 7, wherein the poly(vinyl alcohol) is water-soluble. 9. The electro-optic display according to any one of claims 3 to 8, wherein the degree of hydrolysis of the poly(vinyl alcohol) is 80 to 99.5. 10. The electro-optic display according to claim 1, wherein the adhesive comprises polyurethane, the polyurethane containing one or more quaternary ammonium functional groups in its molecular structure. 11. The electro-optic display according to claim 10, wherein the polyurethane has a weight-average molecular weight of 1,000 to 2,000,000 Daltons. 12. The electro-optic display according to claim 10 or claim 11, wherein the polyurethane is water-soluble or water-dispersible. 13. The electro-optic display according to any one of claims 10 to 12, wherein the polyurethane is crosslinked. 14. The electro-optic display according to any one of claims 10 to 13, wherein the polyurethane is selected from polyether polyurethane, polyester polyurethane, and polycarbonate polyurethane. 15. The electro-optic display according to any one of claims 1 to 14, wherein, by weight of the electro-optic material layer, the electro-optic material layer comprises 85 to 97 wt% microcapsules and 15 to 3 wt% binder. 16. The electro-optic display according to any one of claims 1 to 15, wherein the electrophoretic medium comprises four types of charged pigment particles: a first type of charged pigment particle, a second type of charged pigment particle, a third type of charged pigment particle, and a fourth type of charged pigment particle, each type of charged pigment particle having a different color than all other types of charged pigment particles. 17. The electro-optic display according to claim 16, wherein the electrophoretic medium further comprises a fifth type of charged pigment particles. Claims 1 / 2 Page 2 CN 121941953 A 18. The electro-optic display of claim 16, wherein the colors of the first, second, third, and fourth charged pigment particles are selected from white, black, yellow, cyan, magenta, green, blue, and red. 19. The electro-optic display of claim 16, wherein the charged pigment particles of the first type are negatively charged, andFurthermore, the charged pigment particles of the second, third, and fourth types are positively charged. 20. A method of manufacturing an electro-optic display, the method comprising the steps of: providing an aqueous dispersion of a plurality of microcapsules, each of the plurality of microcapsules comprising an electrophoretic medium comprising a plurality of charged pigment particles and a nonpolar liquid; mixing an aqueous adhesive solution or dispersion with the aqueous dispersion of the plurality of microcapsules to form an aqueous microcapsule slurry, the adhesive solution or dispersion comprising a polymer containing one or more quaternary ammonium functional groups in its molecular structure; providing a first electrode layer comprising a light-transmitting electrode having a surface; applying the aqueous microcapsule slurry to the surface of the first electrode layer to form an aqueous microcapsule layer; drying the aqueous microcapsule layer to form an electro-optic material layer on the first electrode layer; applying an adhesive composition to the electro-optic material layer to form an adhesive layer, the electro-optic material layer being disposed between the first electrode layer and the adhesive layer; and attaching a release sheet to the adhesive layer to form a front panel laminate, the adhesive layer in the front panel laminate being disposed between the electro-optic material layer and the release sheet; Remove the release sheet to expose the adhesive layer; attach a backing plate to the exposed surface of the adhesive layer, the backing plate including a second electrode layer. Claims 2 / 2 Page 3 CN 121941953 A Electro-optic display having an electro-optic material layer, the electro-optic material layer having an adhesive and the adhesive comprising a polymer having quaternary ammonium groups and a method of manufacturing the same

[0001] Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 546,376, filed October 30, 2023, which is incorporated herein by reference in its entirety along with all other patents and patent applications disclosed herein.

[0003] Field of the Invention

[0004] The present invention relates to an electro-optic display comprising an electro-optic material layer comprising an electrophoretic medium encapsulated in a plurality of microcapsules dispersed in an adhesive. The adhesive of the electro-optic material layer comprises a polymer having one or more quaternary ammonium functional groups in its molecular structure. The polymer of the adhesive can improve electro-optical performance and enable an efficient and robust method of manufacturing an electro-optical display.

[0005] Background of the Invention

[0006] The terms “bistable” and “bistable” are used herein in their conventional meaning in the art to refer to a display comprising display elements having a first display state and a second display state that are different in at least one optical property, and such that after either given element has been driven to present its first display state or second display state by an addressing pulse of finite duration, the state will persist for at least several times, for example at least four times, after the addressing pulse has terminated.The shortest duration of the addressing pulse required to change the state of a display element. As shown in U.S. Patent No. 2002 / 0180687, some particle-based electrophoretic displays capable of displaying grayscale are stable not only in their extreme black and white states but also in their intermediate gray states, as are some other types of electro-optical displays. This type of display is aptly referred to as "multistable" rather than bistable, but for convenience, the term "bistable" may be used herein to encompass both bistable and multistable displays.

[0007] Particle-based electrophoretic displays have been a focus of research and development for many years. In this type of display, multiple charged pigment particles move through a fluid under the influence of an electric field. Compared to liquid crystal displays, electrophoretic displays can have good brightness and contrast, wide viewing angles, bistable states, and low power consumption. However, long-term image quality issues have hindered their widespread application. For example, the pigment particles constituting an electrophoretic display tend to settle, resulting in insufficient lifespan for these displays.

[0008] As mentioned above, the electrophoretic medium requires the presence of a fluid. In most existing electrophoretic media, the fluid is a liquid, but gaseous fluids can also be used to produce electrophoretic media; see, for example, Kitamura, T., et al., “Electrical toner movement for electronic paper-like display”, IDW Japan, 2001, Paper HCS1-1 and Yamaguchi, Y., et al., “Toner display using insulative particles charged triboelectrically”, IDW Japan, 2001, Paper AMD4-4. See also U.S. Patent Publication No. 2005 / 0001810; European Patent Applications 1,462,847; 1,482,354; 1,484,635; 1,500,971; 1,501,194; 1,536,271; 1,542,067; 1,577,702; 1,577,703 and 1,598,694; and International Applications WO2004 / 090626; WO2004 / 079442 and WO2004 / 001498. When such gas-based electrophoretic media are used in orientations that allow particle sedimentation, for example in a sign where the medium is positioned in a vertical plane, the medium appears to be susceptible to the same type of problems as liquid-based electrophoretic media due to such sedimentation. Indeed, particle sedimentation in gas-based...The problem appears to be more severe in gaseous electrophoretic media than in liquid-based electrophoretic media because gaseous suspensions have a lower viscosity compared to liquid suspensions, causing charged pigment particles in the electrophoretic medium to settle more quickly.

[0009] Numerous patents and applications describing encapsulated electrophoretic media, assigned to or attributed to MIT and E Ink Corporation, have recently been published. Such encapsulated electrophoretic media comprise a plurality of vesicles, each vesicle comprising an inner phase and a vesicle wall surrounding the inner phase, which contains electrophoretically moving charged pigment particles suspended in a liquid suspension. Typically, the vesicles themselves are held in a polymer binder to form a coherent layer between the two electrodes. The media of this type of package are described, for example, in numbers 5,930,026; 5,961,804; 6,017,584; 6,067,185; 6,118,426; 6,120,588; 6,120,839; 6,124,851; 6,130,773; 6,130,774; 6,172,798; 6,177,921; 6,232,950; 6,249,271; 6,252,564; 6,262,706; 6,262,833; 6,300,932; 6,312,304; 6,312,971; 6,323,989; 6,327 072;6,376,828;6,377 ,387;6,392, 785;6,392,786;6,413,790;6,422,687;6,445,374;6,445,489;6,459,418;6,473,072;6, 480,182;6,498,114;6,504 ,524;6,506,438;6,512,354;6,515,649;6,518,949;6,521 , 489; 6,531,997; 6,535,197; 6,538,801; 6,545,291; 6,580,545; 6,639,578; 6,652,075; 6,657,772; 6,664,944; 6,680,725; 6,683,333; 6,704,133; 6,710,540; 6,721,083; 6,724,519; 6,727,881; 6,738,050; 6,750,473; 6,753,999; 6,816,147; 6,819,471; 6,822,782; 6, 825,068; 6,825,829; 6,825,970; 6,831769;6,839,158;6,842,167;6,842,279;6,842, 657;6,864,875;6,865,010;6,866,760;6,870,661;6,900,851;6,922,276;6,950,200;6, 958,848;6,967,640;6,982,178;6,987,603;6,995,550;7,002,728;7,012,600;7,012, U.S. Patents Nos. 735; 7,023,430; 7,030,412; 7,030,854; 7,034,783; 7,038,655; 7,061,663; 7,071,913; 7,075,502; 7,075,703; 7,079,305; 7,106,296; 7,109,968; 7,110,163; 7,110,164; 7,116,318; 7,116,466; 7,119,759 and 7,119,772; and U.S. Patents Nos. 2002 / 0060321 and 2002 / 0090980; 2002 / 0180687; 2003 / 0011560; 2003 / 0102858; 2003 / 0151702; 2003 / 0222315; 2004 / 0014265; 2004 / 0075634; 2004 / 0094422; 2004 / 0105036; 2004 / 0112750; 2004 / 0119681; 2004 / 0136048; 2004 / 0155857; 2004 / 0180476; 2004 / 0190114; 2004 / 0196215; 2004 / 0226820; 2004 / 0239614; 2004 / 0257635; 2004 / 0263947; 2005 / 0000813; 2005 / 0007336; 2005 / 0012980; 2005 / 0017944; 2005 / 0018273; 2005 / 0024353; 2005 / 0062714; 2005 / 0067656; 2005 / 0078099; 2005 / 0099672; 2005 / 0122284; 2005 / 0122306; 2005 / 0122563; 2005 / 0122565; 2005 / 0134554; 2005 / 0146774; 2005 / 0151709; 2005 / 0152018; 2005 / 0152022; 2005 / 0156340; 2005 / 0168799; 2005 / 0179642; 2005 / 0190137; 2005 / 0212747; 2005 / 0213191; 2005 / 0219184; 2005 / 0253777; 2005 / 0270261; 2005 / 0280626; 2006 / 0007527; 2006 / 0024437; 2006 / 0038772; 2006 / 0139308; 2006 / 0139310; 2006 / 0139311; U.S. Patent Application Publications Nos. 2006 / 0176267; 2006 / 0181492; 2006 / 0181504; 2006 / 0194619; 2006 / 0197736; 2006 / 0197737; 2006 / 0197738; 2006 / 0198014; 2006 / 0202949 and 2006 / 0209388; and International Application Publications Nos. WO00 / 38000; WO00 / 36560; WO00 / 67110 and WO01 / 07961; and European Patents Nos. 1,099,207B1 and 1,145,072B1.

[0010] Many of the aforementioned patents and applications recognize that the walls surrounding discrete microcapsules in an encapsulated electrophoretic medium can be replaced by a continuous phase, thereby producing a so-called polymer-dispersed electrophoretic display, wherein the electrophoretic medium comprises discrete droplets of multiple electrophoretic fluids and a continuous phase of polymer material, and recognizes that although the discrete capsule membrane is not associated with each individual droplet, the discrete droplets of electrophoretic fluids within such a polymer-dispersed electrophoretic display can also be considered as capsules or microcapsules; see, for example, U.S. Patent No. 6,866,760 mentioned above. Therefore, for the purposes of this application, such polymer-dispersed electrophoretic media are considered a subtype of encapsulated electrophoretic media.

[0011] A related type of electrophoretic display is the so-called “micro-unit electrophoretic display.” In a micro-unit electrophoretic display, charged pigment particles and suspended fluids are not encapsulated within microcapsules, but are retained within multiple cavities formed within a carrier medium, typically a polymer film. See, for example, International Application Publication No. WO02 / 01281 and U.S. Application Publication No. 2002 / 0075556, both assigned to Sipix Imaging, Inc.

[0012] Although electrophoretic media are generally opaque (because, for example, in many electrophoretic media, charged pigment particles essentially block visible light from passing through the display) and operate in a reflective mode, many electrophoretic displays can be fabricated in a so-calledOperating in "shutter mode," one display state is substantially opaque, and the other is translucent. See, for example, U.S. Patents 6,130,774 and 6,172,798, mentioned above, and U.S. Patents 5,872,552; 6,144,361; 6,271,823; 6,225,971 and 6,184,856. Dielectric electrophoretic displays, similar to electrophoretic displays but dependent on changes in electric field strength, can operate in a similar mode; see U.S. Patent 4,418,346.

[0013] Encapsulated electrophoretic displays generally do not suffer from the aggregation and sedimentation failure modes of conventional electrophoretic apparatus and offer further advantages, such as the ability to print or coat the display on a wide variety of flexible and rigid substrates (the term "printing" is intended to include all forms of printing and coating, including but not limited to: volumetric coating, such as patch die coating, slot or extrusion coating, cascade coating, curtain coating; roll coating, such as doctor blade coating, forward and reverse roll coating; gravure coating; dip coating; spray coating; meniscus coating; spin coating; brush coating; air knife coating; screen printing; electrostatic printing; thermal printing; inkjet printing; and other similar techniques). Therefore, the resulting display can be flexible. Furthermore, because the display medium can be printed (using various methods), the display itself can be manufactured at low cost.

[0014] Electro-optic displays include electrophoretic media encapsulated in microcapsules, requiring the use of polymeric adhesives to form a coherent layer that can be disposed between two electrodes. Typically, multiple microcapsules are mixed with an adhesive to form an aqueous microcapsule slurry. Adhesives commonly used in aqueous microcapsule slurries contain anionic polyurethane. The aqueous microcapsule slurry is then coated and dried / cured to form an electro-optic material layer. If the aqueous microcapsule slurry is stored at room temperature before its use, special care is needed to prevent microbial growth because the microcapsule walls typically contain gelatin. Due to the proteinaceous nature of gelatin, it can be readily degraded by proteases produced by bacteria or fungi growing in the aqueous microcapsule slurry. Such degradation can be mitigated by (a) storing the aqueous microcapsule slurry in a refrigerator at low temperatures, (b) using the aqueous microcapsule slurry only for a short time after its preparation, or (c) adding a biocidal agent to the aqueous microcapsule slurry. However, storing the aqueous microcapsule slurry in a refrigerator and / or using it shortly after its preparation is not only inconvenient but also increases manufacturing costs. While the addition of biocides to aqueous microencapsulation slurries slows microbial growth, the inventors of this invention have observed that biocides require a high (or low) pH to function, or that the biocides may affect the pH over time, leading to variations in the pH of the aqueous microencapsulation slurry during storage.The pH can be high or low. However, storing microcapsules in an aqueous medium with a high (or low) pH may lead to hydrolysis of the microcapsule walls. Furthermore, since biocides are typically small organic molecules, they can migrate from the continuous phase of the aqueous microcapsule slurry (or the continuous phase of the electrophoretic layer of the display) to other layers of the microcapsule and / or electro-optic display, resulting in adverse effects on the electro-optic performance of the corresponding display. Therefore, it is desirable to eliminate conventionally used biocides from aqueous microcapsule compositions and to develop aqueous microcapsule slurry compositions that allow for long-term storage. It is also desirable to be able to manufacture the corresponding electro-optic displays using convenient and cost-effective methods. The inventors of this invention have surprisingly discovered that using adhesives comprising polymers containing one or more quaternary ammonium functional groups in their molecular structure provides several benefits. Compared to other adhesives comprising anionic or nonionic polyurethanes, such adhesives not only provide antimicrobial activity, but they also provide (i) mechanically robust electro-optic material layers and (ii) electro-optic displays exhibiting improved electro-optic performance. Specification 3 / 12 pages 6 CN 121941953 A

[0015] Overview of the Invention

[0016] In one aspect, the present invention provides an electro-optic display, which sequentially includes a first electrode layer, an electro-optic material layer, and a second electrode layer. The first electrode layer includes a light-transmitting electrode. The electro-optic material layer includes a plurality of microcapsules dispersed in an adhesive. Each of the plurality of microcapsules includes an electrophoretic medium, the electrophoretic medium including a plurality of charged pigment particles and a nonpolar liquid. The adhesive includes a polymer containing one or more quaternary ammonium functional groups in its molecular structure. The second electrode layer includes a plurality of pixel electrodes. The electro-optic display may further include a first adhesive layer disposed between the electro-optic material layer and the second electrode layer. The electro-optic display may further include a second adhesive layer disposed between the electro-optic material layer and the first electrode layer. The electro-optic material layer may further include a biocide. The electro-optic material layer may be substantially free of biocides.

[0017] The adhesive may include poly(vinyl alcohol), the poly(vinyl alcohol) containing one or more quaternary ammonium functional groups in its molecular structure. The weight-average molecular weight of poly(vinyl alcohol) can be from 1,000 to 1,000,000 Daltons, or from 10,000 to 1,000,000 Daltons. Poly(vinyl alcohol) can be crosslinked. For each vinyl alcohol unit of the polymer, poly(vinyl alcohol) can contain 0.03 to 0.4, or 0.05 to 0.2 quaternary ammonium functional groups. The degree of hydrolysis of poly(vinyl alcohol) can be 80 to 99.5, or 86 to 98. Poly(vinyl alcohol) is soluble in water.

[0018] The adhesive can comprise a polyurethane containing one or more quaternary ammonium functional groups in its molecular structure. The weight-average molecular weight of the polyurethane can be from 1,000 to 2,000,000 Daltons. The polyurethane can be crosslinked. For the polymerization...Each polyol unit of the polyurethane may contain 1 to 6, or 2 to 4, quaternary ammonium functional groups. The polyurethane may be cross-linked. The polyurethane is soluble in water or dispersible in water. The polyurethane may be selected from polyether polyurethane, polyester polyurethane, and polycarbonate polyurethane.

[0019] The electro-optic material layer may contain 85% to 97% by weight of microcapsules and 15% to 3% by weight of binder, based on the weight of the electro-optic material layer. The electrophoretic medium may contain four types of charged pigment particles: a first type of charged pigment particle, a second type of charged pigment particle, a third type of charged pigment particle, and a fourth type of charged pigment particle. Each type of charged pigment particle may have a color different from the colors of all other types of charged pigment particles. The electrophoretic medium may also contain a fifth type of charged pigment particle. The colors of the first, second, third, and fourth charged pigment particles may be selected from white, black, yellow, cyan, magenta, green, blue, and red. The first type of charged pigment particles may carry a negative charge, and the second, third, and fourth type of charged pigment particles may carry a positive charge. Alternatively, the charged pigment particles of the first and second types can be negatively charged, and the charged pigment particles of the third and fourth types can be positively charged.

[0020] On the other hand, the present invention provides a method for manufacturing an electro-optic display, the method comprising the steps of: (a) providing an aqueous dispersion of a plurality of microcapsules, each of the plurality of microcapsules comprising an electrophoretic medium comprising a plurality of charged pigment particles and a nonpolar liquid; (b) mixing an aqueous binder solution or dispersion into the aqueous dispersion of the plurality of microcapsules to form an aqueous microcapsule slurry, the binder solution or dispersion comprising a polymer containing one or more quaternary ammonium functional groups in its molecular structure; (c) providing a first electrode layer comprising a light-transmitting electrode having a surface; (d) applying the aqueous microcapsule slurry to the surface of the first electrode layer to form an aqueous microcapsule layer; (e) (g) Drying the aqueous microcapsule layer to form an electro-optic material layer on the first electrode layer; (h) applying an adhesive composition to the electro-optic material layer to form an adhesive layer disposed between the first electrode layer and the adhesive layer; (i) attaching a release liner to the adhesive layer to form a front panel laminate, wherein the adhesive layer in the front panel laminate is disposed between the electro-optic material layer and the release liner; (ii) removing the release liner to expose the adhesive layer; and (k) attaching a backplate to the exposed surface of the adhesive layer, the backplate including a second electrode layer. Specification 4 / 12 pages 7 CN 121941953 A

[0021] Brief Description of the Drawings

[0022] FIG1 illustrates a side view of a portion of the electro-optic display of the present invention, the electro-optic display including a first electrode layer, an electro-optic material layer, an adhesive layer, and a second electrode layer.

[0023] Figure 2 illustrates a side view of a portion of the electro-optic display of the present invention, the electro-optic display including a first electrode layer, a second adhesive layer, an electro-optic material layer, a first adhesive layer, and a second electrode layer.

[0024] Figures 3A and 3B illustrate examples of a method for manufacturing the electro-optic display of the present invention via a front-plate laminate.

[0025] Figure 4 shows color gamut diagrams of a color electro-optic display at two different times; the color electro-optic display is composed of microcapsules formed from a variety of aqueous microcapsule slurries.

[0026] Detailed Description of the Invention

[0027] Unless otherwise stated, the term “molecular weight” or “MW” as used herein refers to weight-average molecular weight. Weight-average molecular weight can be measured by gel permeation chromatography.

[0028] The term “substantially biocide-free” refers to the electro-optic material layer, meaning that the electro-optic material layer contains less than 0.0001% by weight of biocide, or less than 0.001% by weight of biocide, or less than 0.01% by weight of biocide, based on the weight of the electro-optic material layer. For the purposes of this application, polymers containing one or more quaternary ammonium functional groups are not considered biocides.

[0029] The degree of hydrolysis of poly(vinyl alcohol) is typically reported by the manufacturer of such polymers, and it indicates the proportion of vinyl alcohol units (moles) in the polymer to the total vinyl units. Other units are typically vinyl acetate (ester groups).

[0030] A compound is “soluble in liquid” if at least 1 gram of the compound can be dissolved in 100 grams of liquid.

[0031] A quaternary ammonium functional group, also known as a quaternary ammonium group, is a cationic polyatomic functional group having a nitrogen atom covalently bonded to four carbon atoms, each of which is part of the functional group, wherein the functional group may be independently selected from alkyl, aryl, or other organic functional groups.

[0032] As described in U.S. Patent No. 6,982,178, a typical electro-optic display may have an electro-optic material layer comprising an electrophoretic medium encapsulated in microcapsules or microunits. FIG1 shows a side view of a portion of an electro-optic display having microcapsules. The electro-optic display 100 includes a first electrode layer 101, an electro-optic material layer 102, a first adhesive layer 104, and a second electrode layer 103. The first electrode layer 101 includes a light-transmitting electrode, and the second electrode layer includes a plurality of pixel electrodes. The first adhesive layer 104 connects the electro-optic material layer 102 to the second electrode layer. The electro-optic material layer 102 includes a plurality of microcapsules 112 and an adhesive 132. Each microcapsule has a microcapsule wall. Each microcapsule contains an electrophoretic medium 122 having charged pigment particles in a nonpolar liquid. The electrophoretic medium 122 may contain multiple first-type charged pigment particles and multiple second-type charged pigment particles. The electrophoretic medium may also contain multiple third-type charged pigment particles.122 may also contain a plurality of fourth type charged pigment particles. Electrophoretic medium 122 may also contain a plurality of fifth type charged pigment particles. Typically, the plurality of microcapsules are retained in polymer adhesive 132. A viewer can view the image of electro-optic display 100 from viewing side 150. As described in the background of the invention and outlined in Figures 3A and 3B, electro-optic display 100 may be constructed of a front panel laminate. The electro-optic device of Figure 1 may be a color electro-optic display, meaning that it can display images including multiple colors.

[0033] Another example of an electro-optic display is shown in Figure 2. Figure 2 illustrates a side view of a portion of an electro-optic display having microcapsules. Electro-optic display 200 has viewing side 150. It sequentially includes a first electrode layer 101, a second adhesive layer 105, an electro-optic material layer 102, a first adhesive layer 104, and a second electrode layer 103, the first electrode layer 101 including a light-transmitting electrode, and the second electrode layer including a plurality of pixel electrodes. A second adhesive layer 105 connects the first electrode layer 101 to the electro-optic material layer 102. A first adhesive layer 104 connects the electro-optic material layer 102 to the second electrode layer 103. The electro-optic material layer 102 comprises a plurality of microcapsules 112 and an adhesive 132. Each microcapsule has a microcapsule wall and contains an electrophoretic medium 122 having charged pigment particles in a non-polar liquid. The electrophoretic medium 122 may contain a plurality of first-type charged pigment particles and a plurality of second-type charged pigment particles. The electrophoretic medium may also contain a plurality of third-type charged pigment particles. The electrophoretic medium 122 may also contain a plurality of fourth-type charged pigment particles. The electrophoretic medium 122 may also contain a plurality of fifth-type charged pigment particles. Typically, the plurality of microcapsules are retained in the polymer adhesive 132. The electro-optic material layer 100 may be constructed of a dual release sheet as described in the background of the invention. The electro-optic device of Figure 2 can be a color display, meaning it can display images including multiple colors.

[0034] The microcapsule electro-optic displays of Figures 1 and 2 may also include a light-transmitting front substrate (not shown in Figures 1 and 2) adjacent to a first electrode layer 101, wherein the electrode layer is disposed between the front substrate and the electro-optic material layer (for the display of Figure 1) or between the front substrate and the second adhesive layer (for the display of Figure 2). The front substrate may be a plastic film, such as a polyethylene terephthalate (PET) sheet with a thickness of 25 to 200 μm. The front substrate may also include one or more additional layers, such as a protective layer that absorbs ultraviolet radiation, a barrier layer that prevents oxygen or moisture from entering the display, and an anti-reflective coating that improves the optical performance of the display.

[0035] In addition to the microcapsules containing the electrophoretic medium, the electro-optic material layer of the microcapsule electro-optic display also contains an adhesive.The adhesive comprises a polymer that facilitates the formation of a mechanically robust electro-optic material layer for an electro-optic display. A common method for forming the electro-optic material layer involves mixing an aqueous microcapsule dispersion with an aqueous adhesive solution or dispersion. This aqueous composition is also referred to herein as an aqueous microcapsule slurry or microcapsule paste. During the manufacture of the electro-optic display, the aqueous microcapsule slurry is applied to a surface, and the aqueous coating is subsequently dried or cured to form the electro-optic material layer. That is, the electro-optic material layer typically comprises a monolayer of microcapsules in the adhesive.

[0036] The adhesive for the electro-optic material layer of the present invention comprises a polymer containing one or more quaternary ammonium functional groups in its molecular structure. That is, the adhesive comprises a polymer having cationic functional groups. Non-limiting polymers include poly(vinyl alcohol), polyurethane, acrylate, and methacrylate polymers containing one or more quaternary ammonium functional groups in their molecular structure.

[0037] The adhesive may comprise poly(vinyl alcohol) containing one or more quaternary ammonium functional groups in its molecular structure. The weight-average molecular weight of poly(vinyl alcohol) can be from 1,000 to 1,000,000 Daltons, 5,000 to 800,000 Daltons, 10,000 to 700,000 Daltons, or 15,000 to 600,000 Daltons. The poly(vinyl alcohol) of the adhesive can be crosslinked or uncrosslinked. The poly(vinyl alcohol) of the adhesive is soluble in water. The degree of hydrolysis of the poly(vinyl alcohol) of the adhesive can be 70 to 99.5, 80 to 99, 86 to 98, or 88 to 95.

[0038] The poly(vinyl alcohol) may contain 2 to 2,000, 10 to 1,500, 100 to 1,200, or 500 to 1,000 quaternary ammonium functional groups in its molecular structure. For each vinyl alcohol unit of the polymer, the poly(vinyl alcohol) of the adhesive may contain 0.03 to 0.4, 0.04 to 0.3, or 0.05 to 0.2 quaternary ammonium functional groups. The nitrogen content of the poly(vinyl alcohol) of the adhesive may be 0.2% to 12% by weight, 0.5% to 10% by weight, 0.7% to 9% by weight, or 1.0% to 8% by weight of nitrogen based on the weight of the poly(vinyl alcohol).

[0039] The adhesive may comprise a polyurethane containing one or more quaternary ammonium functional groups in its molecular structure. The weight-average molecular weight of the polyurethane may be 1,000 to 2,000,000 Daltons, 5,000 to 1,500,000 Daltons, 10,000 to 1,000,000 Daltons, or 15,000 to 800,000 Daltons. The polyurethane of the adhesive may be crosslinked or uncrosslinked. The polyurethane of the adhesive is soluble in water or dispersible in water. Polyurethanes can contain 2 to 2000, 10 to 1500, 100 to 1200, or 500 to 1000 quaternary ammonium functional groups in their molecular structure. For each polyol unit of the polymer, the polyurethane adhesive can...The polyurethane contains 0.03 to 0.4, 0.04 to 0.3, or 0.05 to 0.2 quaternary ammonium functional groups. The nitrogen content of the polyurethane in the adhesive, i.e., the portion of the polymer containing quaternary ammonium functional groups as described on page 6 / 12 of the specification (CN 121941953 A), may be 0.2% to 12% by weight, 0.5% to 10% by weight, 0.7% to 9% by weight, or 1.0% to 8% by weight of nitrogen based on the weight of the polyurethane.

[0040] The adhesive may contain polyacrylate or polymethacrylate, which contains one or more quaternary ammonium functional groups in its molecular structure. The weight-average molecular weight of the polyurethane may be 1,000 to 2,000,000 Daltons, 5,000 to 1,500,000 Daltons, 10,000 to 1,000,000 Daltons, or 15,000 to 800,000 Daltons. The polyurethane in the adhesive may be crosslinked or uncrosslinked. The adhesive's polyacrylate or polymethacrylate is soluble in or dispersible in water. The polyacrylate or polymethacrylate may contain 2 to 2000, 10 to 1500, 100 to 1200, or 500 to 1000 quaternary ammonium functional groups in its molecular structure. For each monomer unit of the polymer, the adhesive's polyacrylate or polymethacrylate may contain 0.03 to 0.4, 0.04 to 0.3, or 0.05 to 0.2 quaternary ammonium functional groups. The nitrogen content of the adhesive's polyacrylate or polymethacrylate, i.e., the portion of the polymer containing quaternary ammonium functional groups, may be 0.2% to 12% by weight, 0.5% to 10% by weight, 0.7% to 9% by weight, or 1.0% to 8% by weight of nitrogen based on the weight of the polyacrylate or polymethacrylate.

[0041] The adhesive of the electro-optic material layer of the electro-optic display of the present invention may comprise a combination of polymers. The polymer of the adhesive may be selected from poly(vinyl alcohol), polyurethane, polyacrylate, polymethacrylate, polyurea, and combinations thereof.

[0042] The adhesive of the electro-optic material layer of the electro-optic display of the present invention may be substantially free of biocides. Alternatively, the electro-optic material layer of the electro-optic display of the present invention may contain biocides. The content of biocides in the electro-optic material layer may be 0.2 to 10% by weight, or 1 to 8% by weight, or 2 to 6% by weight, based on the weight of the electro-optic material layer. Non-limiting examples of biocides include isothiazolinones, tetramethylolphosphonium sulfate (THPS), 2,2-dibromo-3-nitrilopropionamide, bromonitrile, and mixtures thereof.

[0043] As described above, the microcapsules may be prepared in an aqueous medium and then mixed with an aqueous adhesive solution or dispersion to prepare...Aqueous microcapsule slurry preparation. The aqueous microcapsule slurry containing cationic polymers of the present invention is less prone to microbial growth during its storage. Furthermore, the electro-optic material layer of the electro-optic display of the present invention may not contain conventional biocides, as biocides are small molecules that tend to diffuse through the layers of the electro-optic display, negatively affecting the electro-optic performance of the display. The electro-optic material layer of the electro-optic display of the present invention does not contain conventional biocides, achieving the formation of the electro-optic material layer from an aqueous microcapsule slurry with a neutral pH, avoiding the problem of microcapsule hydrolysis observed in electro-optic material layers formed from aqueous microcapsule slurries with alkaline or acidic pH values.

[0044] In the following text of the present invention, electrophoretic medium refers to the composition present inside the microcapsule. For electro-optic display applications containing electrophoretic medium, the microcapsule may contain at least one type of charged pigment particles in a nonpolar fluid. The electrophoretic medium may contain one type of charged pigment particles or more than one type of charged pigment particles, each type of particle having different color, charge, and charge polarity. Charged pigment particles move through an electrophoretic medium under the influence of an electric field, which is applied across an electro-optical material layer. The charged pigment particles can be inorganic or organic pigments that have undergone polymer surface treatment to improve their stability. The electrophoretic medium can contain charged pigment particles of white, black, cyan, magenta, yellow, blue, green, red, and other colors. The electrophoretic medium may also include charge control agents, charge aids, rheology modifiers, and other additives. Examples of nonpolar fluids include hydrocarbons such as Isopar, DECALIN, 5-ethylidene-2-norbornene, fatty oils, paraffin oils, silicone fluids, aromatics such as toluene, xylene, phenylxylene ethane, dodecylbenzene, or alkylnaphthalene, halogenated solvents such as perfluorodecahydronaphthalene, perfluorotoluene, perfluoroxylene, dichlorotrifluorotoluene, 3,4,5-trichlorotrifluorotoluene, chloropentafluorobenzene, dichlorononane, or pentachlorobenzene, and perfluorinated solvents such as FC-43, FC-70, or FC-5060 from 3M Company, St. Paul, Minnesota; low molecular weight halogenated polymers such as poly(perfluoropropylene oxide) and poly(chlorotrifluoroethylene) from TCI America, Portland, Oregon, as described on page 7 / 12 of the specification (CN 121941953 A); and Halocarbon Products from River Edge, New Jersey. Halocarbon Oils from Corp., perfluoropolyalkyl ethers, such as Galden from Ausimont or Krytox Oils, and Greases from DuPont in Delaware.K-Fluid series, from Dow-corning, polydimethylsiloxane silicone oil (DC-200).

[0045] The electrophoretic medium may contain two or more types of charged pigment particles. The electrophoretic medium may contain four types of charged pigment particles, type 1, type 2, type 3, and type 4 charged pigment particles. Type 1, type 2, type 3, and type 4 charged pigment particles may contain pigments of type 1, type 2, type 3, and type 4 respectively having first, second, third, and fourth colors. The first, second, third, and fourth colors may be different from each other. Type 1 charged pigment particles may contain inorganic pigments and have a first charge polarity. Type 2 and type 3 charged pigment particles may have a second charge polarity opposite to the second charge polarity. Type 4 charged pigment particles may have either a first charge polarity or a second charge polarity. Type 1 charged pigment particles may be white. Type 2, type 3, and type 4 charged pigment particles may have colors selected from cyan, magenta, and yellow.

[0046] Figures 3A and 3B outline an example of a portion of a method for manufacturing an electro-optic display 100 via an electro-optic assembly 200 (front panel laminate). A first electrode layer 101 is provided, and in step 1 of Figure 3A, an aqueous microcapsule slurry (not shown in Figure 3A) is applied to the surface of the first electrode layer 101. The electro-optic slurry is dried to form an electro-optic material layer 102 on the first electrode layer 101. In step 2 of Figure 3A, an adhesive composition 114 is applied to the electro-optic material layer 102 to form an adhesive layer 104. In the resulting structure, the electro-optic material layer 102 is disposed between the first electrode layer 101 and the adhesive layer 104. In step 3 of Figure 3A, a release liner is attached to the adhesive layer 104 to form the front panel laminate 200. The adhesive layer 104 in the front panel laminate 200 is disposed between the electro-optic material layer 102 and the release liner 105.

[0047] As shown in FIG. 3B, the front plate laminate 200 can be used to form the optoelectronic display 100 of the present invention. Specifically, in step 4 of FIG. 3B, the release liner 105 is removed, exposing the adhesive layer 104. A back plate can be bonded to the exposed adhesive layer 104 to form the electro-optic display 100. The back plate includes a second electrode layer (not shown in FIG. 3B). The second electrode layer may include a plurality of pixel electrodes. Example

[0048] Example 1: Preparation of electrophoretic medium.

[0049] The electrophoretic medium is prepared by a combination of four charged pigment particle dispersions, namely, a white charged pigment particle dispersion in Isopar E, a cyan charged pigment particle dispersion in Isopar E, a magenta charged pigment particle dispersion in Isopar E, and a yellow charged pigment particle dispersion in Isopar E. The charge is transferred under stirring.The control agent CCA-111 and polyisobutylene were added to the combined dispersion to provide the electrophoretic medium. The structure and preparation of CCA-111 are described in U.S. Application Publication No. 2020 / 0355978.

[0050] Example 2A: Preparation of aqueous microcapsule dispersion.

[0051] The electrophoretic medium from Example 1 was encapsulated in a gelatin / gum arabic aggregate using the following method. Gelatin was dissolved in deionized water at 40°C and stirred vigorously. The electrophoretic medium from Example 1 was added dropwise to the stirred gelatin solution through a tube, the outlet of which was below the surface of the stirred solution. The resulting mixture was maintained at 42.5°C and stirred vigorously to generate droplets of the electrophoretic medium in a continuous gelatin-containing aqueous phase. An aqueous solution of gum arabic was then added to the mixture at 42.5°C, and the pH of the mixture was lowered to approximately 5 to induce the formation of a gelatin / gum arabic aggregate, thereby forming microcapsules. The temperature of the resulting mixture was then lowered to 9°C, and an aqueous solution of glutaraldehyde (crosslinking agent) was added (see page 8 / 12, CN 121941953 A). The resulting mixture was then heated to 25°C and stirred vigorously for 12 hours. The prepared capsules were separated by sieving using sieves with mesh sizes of 20 μm and 45 μm to obtain capsules with an average diameter of approximately 44 μm.

[0052] Example 3A: Preparation of an aqueous microcapsule dispersion containing a biocide.

[0053] The biocide Proxil TN was mixed into the dispersion, namely the aqueous microcapsule dispersion of Example 2A. The weight ratio of microcapsules to biocide was 370:1. The weight of the microcapsules used to calculate this ratio does not include the aqueous medium of the aqueous microcapsule dispersion.

[0054] Example 4A: Preparation of an aqueous microcapsule slurry.

[0055] Cationic poly(vinyl alcohol) was added to the aqueous microcapsule dispersion of Example 2A and mixed to form an aqueous microunit slurry. The weight ratio of microcapsules to cationic poly(vinyl alcohol) binder was 1:0.06. The weight of the microcapsules used to calculate this ratio does not include the aqueous medium of the aqueous microcapsule dispersion. The final aqueous microcapsule slurry contained 60% water. The cationic poly(vinyl alcohol) was supplied by Kuraray, trade name CM-318.

[0056] Example 5A: Preparation of an aqueous microcapsule slurry containing a biocide.

[0057] The biocide Proxil TN was mixed into the dispersion, namely the aqueous microcapsule dispersion of Example 4A. The weight ratio of microcapsules to biocide was 370:1. The weight of the microcapsules used to calculate this ratio does not include the aqueous medium of the aqueous microcapsule slurry.

[0058] Comparative Example 2B: The aqueous microcapsule dispersion from Example 2A was stored at 25°C for 24 weeks.

[0059] Comparative Example 3B: The aqueous microcapsule dispersion from Example 3A was stored at 25°C for 24 weeks.

[0060] Example 4B: The aqueous microcapsule slurry from Example 4A was stored at 25°C for 24 weeks.

[0061] Example 5B: The aqueous microcapsule slurry from Example 5A was stored at 25°C for 24 weeks.

[0062] Before the 24-week storage period at 25°C, microcapsules were extracted from each sample of Examples 2A, 3A, 4A, and 5A, and the rupture force of the extracted microcapsules was determined by nanoindentation testing. After the 24-week storage period at 25°C, microcapsules were extracted from each sample of Comparative Example 2B, Comparative Example 3B, Example 4B, and Example 5B, and the rupture force of the extracted microcapsules was determined by nanoindentation testing. In addition, the pH values ​​of the aqueous microcapsule dispersions of Examples 2A and 3A were measured before the 24-week storage period at 25°C. After the 24-week storage period at 25°C, the pH values ​​of the aqueous microcapsule dispersions of Comparative Examples 2B and 3B were measured. The pH results are summarized in Table 1. The results of the bursting force of the extracted microcapsules are summarized in Table 2.

[0063] Method for determining the bursting force of microcapsules.

[0064] Microcapsules were removed from the aqueous microcapsule dispersion or from the aqueous microcapsule slurry and placed on the sensor of a Hyistron TI 750 Ubi Triboscope. The bursting force was determined by nanoindentation testing in load-controlled feedback mode. The test was performed by applying force to press the indenter probe into the sample surface and then reducing the force to withdraw the probe. The applied load and the displacement of the indenter into the sample were continuously monitored. The results are reported in microNewtons / micrometers (μN / μm).

[0065] Table 1: Summary of pH values ​​of the aqueous microcapsule dispersion composition before and after storage at 25°C for 24 weeks.

[0066]

[0067] Table 2: Summary of microcapsule rupture forces of aqueous microcapsule dispersion compositions and aqueous microcapsule slurry compositions before and after storage at 25°C for 24 weeks.

[0068]

[0069] Table 2 shows that in aqueous samples aged at 25°C for 24 weeks, the higher the pH value caused by the biocide (in Examples 3B and 5B), the lower the rupture force compared to samples without biocide (Examples 2B and 4B). This demonstrates the adverse effect of conventional small molecule biocides on the integrity of microcapsules. Higher pH conditions may lead to some hydrolysis of the material of the microcapsule wall, resulting in lower rupture forces of broken microcapsules. The highest rupture force was observed in Example 5B of the present invention, which was aged as an aqueous microcapsule slurry containing a polymer with one or more quaternary ammonium functional groups and without biocide.

[0070] Comparative Example 2C: Preparation of an electro-optic display, i.e., preparation of an electro-optic display from aqueous microcapsule dispersion 2B

[0071] The aqueous microcapsule dispersion of Example 2B, stored at 25°C for 24 weeks, was mixed with a cationic poly(vinyl alcohol) binder to prepare an aqueous microcapsule slurry. The weight ratio of microcapsules to binder in the aqueous microcapsule slurry was 1:0.06. The weight of the microcapsules used to calculate this ratio does not include the aqueous medium of the aqueous microcapsule dispersion. The aqueous microcapsule slurry was used to prepare an electro-optic display comprising a first electrode layer, an electro-optic material layer, an adhesive layer, and a second electrode layer. For comparison, an electro-optic display was also prepared from the aqueous microcapsule dispersion of Example 4A (before it was stored at 25°C). This electro-optic display can be regarded as a control of the display of Example 2C at time zero. Their electro-optic performance was evaluated by measuring the total color gamut of the electro-optic displays.

[0072] Comparative Example 3C: Preparation of an electro-optic display from aqueous microcapsule dispersion 2C

[0073] The aqueous microcapsule dispersion of Example 3B, stored at 25°C for 24 weeks, was mixed with a cationic poly(vinyl alcohol) binder to prepare an aqueous microcapsule slurry. The weight ratio of microcapsules to binder in the aqueous microcapsule slurry was 1:0.06. The weight of the microcapsules used to calculate this ratio did not include the aqueous medium of the aqueous microcapsule dispersion. An electro-optic display comprising a first electrode layer, an electro-optic material layer, an adhesive layer, and a second electrode layer was prepared using the aqueous microcapsule slurry. For comparison, an electro-optic display was also prepared from the aqueous microcapsule dispersion of Example 5A (before it was stored at 25°C). This electro-optic display can be considered as a zero-time control of the display of Example 3C. The electro-optic performance of the electro-optic display was evaluated by measuring the total color gamut.

[0074] Example 4C: Electro-optic display prepared from aqueous microcapsule slurry 3C.

[0075] An electro-optic display comprising a first electrode layer, an electro-optic material layer, an adhesive layer, and a second electrode layer was prepared using the aqueous microcapsule slurry of Example 4B stored at 25°C for 24 weeks. For comparison, an electro-optic display was also prepared from the aqueous microcapsule dispersion of Example 4A (before it was stored at 25°C). This electro-optic display can be considered a control of the display of Example 4C at time zero. Their electro-optic performance was evaluated by measuring the total color gamut of the electro-optic displays.

[0076] Example 5C: Electro-optic display prepared from aqueous microcapsule slurry 5B.

[0077] An electro-optic display comprising a first electrode layer, an electro-optic material layer, an adhesive layer, and a second electrode layer was prepared using the aqueous microcapsule slurry of Example 5B stored at 25°C for 24 weeks. For comparison, an electro-optic display was also prepared from the aqueous microcapsule dispersion of Example 5A (before its storage at 25°C). This electro-optic display can be considered a control of the display of Example 5C at time zero. Their electro-optic performance was evaluated by measuring the total color gamut of the electro-optic displays.

[0078] The total color gamut of the electro-optic displays of Examples 2C, 3C, 4C, and 5C and the corresponding control electro-optic displays (at time zero) is provided in Table 3 and Figure 4.

[0079] Method for color gamut measurement.

[0080] The electro-optic displays of Comparative Examples 2C, 3C, and Examples 4C and 5C were evaluated by measuring their color gamut before aging (T=0) and after 24 weeks of aging at 25°C. The electro-optic displays of Comparative Examples 2C, 3C, and Examples 4C and 5C were electrically driven to generate eight optical states. An electrophoresis apparatus was addressed 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 rear electrode of the display, assuming that the electrode on the front (viewing) surface of the display is the first electrode for all pixels and is connected to ground. The color states of the displays were recorded (measured in CIELab L*, a*, and b* units). The color gamut of each display was measured by calculating the volume of the convex hull, which contains each color state generated by the set of test waveforms. The eight color states generated were red, green, blue, yellow, cyan, magenta, white, and black (R, G, B, Y, C, M, W, and K). The color gamut was reported in DE3 units. A wider color gamut, i.e., a larger space, means better electro-optic performance of the electro-optic device.

[0081] Table 3: Color Gamut Specification of Electro-optic Device 11 / 12 pages 14 CN 121941953 A

[0082]

[0083] For the electro-optic displays of Comparative Examples 2C and 3C, whose electro-optic material layers were prepared using aqueous microcapsule dispersions (containing and without biocide) of Comparative Examples 2B and 3B stored at 25°C, a moderate reduction in color gamut was observed after 24 weeks. As shown in Table 1, the poor performance of the electro-optic device of Comparative Example 3C may be due to an undesirable reaction caused by the higher pH of the aqueous microcapsule dispersion due to the presence of a biocide. In addition, the poor performance may be caused by the presence of mobile biocide, which is a small organic molecule capable of migrating to different parts of the electro-optic material layer (or other layers of the display).

[0084] The electro-optic displays (Examples 4C and 5C) prepared from the aqueous microcapsule slurry stored at 25°C did not show a significant decrease in the color gamut. Polymers containing quaternary ammonium functional groups in the binder can be used as antimicrobial materials without the adverse effects of smaller biocide molecules. As previously observed (Comparative Example 3C vs. Comparative Example 2C), the electro-optic performance of the biocide-containing electro-optic display (Example 5C) was slightly worse than that of the biocide-free electro-optic display of Example 4C.

[0085] Finally, using BD Hycheck, bacterial growth was evaluated on the aqueous microcapsule dispersion sample of Comparative Example 2B after 24 weeks of storage at 25°C and the corresponding aqueous microcapsule slurry of Example 4B after 24 weeks of storage at 25°C by incubating aliquots of the sample at 37°C for 3 days. After a 3-day incubation period, 5% of the surface coated by the aliquot of Comparative Example 2B was...Bacterial colonies were present on the surface coated with the aliquots of Example 5B, but no bacterial colonies were observed. The presence of cationic poly(vinyl alcohol) likely inhibited bacterial growth in the sample of Example 5B. The method involved coating the aqueous sample onto a Hycheck slide and then incubating it at 37°C for 3 days. (The remaining text appears to be a list of references and related documents, which are not translated as they are not part of the main text.)

Claims

1. An electro-optical display, comprising, in sequence: The first electrode layer includes a light-transmitting electrode; An electro-optic material layer comprising a plurality of microcapsules dispersed in an adhesive, each of the plurality of microcapsules comprising an electrophoretic medium comprising a plurality of charged pigment particles and a nonpolar liquid, the adhesive comprising a polymer having one or more quaternary ammonium functional groups in its molecular structure; The second electrode layer includes multiple pixel electrodes.

2. The electro-optic display according to claim 1, wherein, The electro-optic material layer is essentially free of biocides.

3. The electro-optical display according to claim 1 or claim 2, wherein, The adhesive comprises poly(vinyl alcohol), which contains one or more quaternary ammonium functional groups in its molecular structure.

4. The electro-optic display according to claim 3, wherein, The weight-average molecular weight of the poly(vinyl alcohol) is between 1,000 and 1,000,000 Daltons.

5. The electro-optic display according to claim 3 or claim 4, wherein, The poly(vinyl alcohol) is cross-linked.

6. The electro-optical display according to any one of claims 3 to 5, wherein, For each vinyl alcohol unit of the polymer, the poly(vinyl alcohol) contains 0.03 to 0.4 quaternary ammonium functional groups.

7. The electro-optical display according to any one of claims 3 to 5, wherein, For each vinyl alcohol unit of the polymer, the poly(vinyl alcohol) contains 0.05 to 0.2 quaternary ammonium functional groups.

8. The electro-optical display according to any one of claims 3 to 7, wherein, The poly(vinyl alcohol) is water-soluble.

9. The electro-optical display according to any one of claims 3 to 8, wherein, The degree of hydrolysis of the poly(vinyl alcohol) is 80 to 99.

5.

10. The electro-optical display of claim 1, wherein, The adhesive comprises polyurethane, which contains one or more quaternary ammonium functional groups in its molecular structure.

11. The electro-optical display of claim 10, wherein, The weight-average molecular weight of the polyurethane is between 1,000 and 2,000,000 Daltons.

12. The electro-optical display according to claim 10 or claim 11, wherein, The polyurethane is water-soluble or water-dispersible.

13. The electro-optical display according to any one of claims 10 to 12, wherein, The polyurethane is cross-linked.

14. The electro-optical display according to any one of claims 10 to 13, wherein, The polyurethane is selected from polyether polyurethane, polyester polyurethane and polycarbonate polyurethane.

15. The electro-optical display according to any one of claims 1 to 14, wherein, The electro-optic material layer comprises 85 to 97 percent microcapsules and 15 percent to 3 percent binder by weight.

16. The electro-optical display according to any one of claims 1 to 15, wherein, The electrophoretic medium contains four types of charged pigment particles: a first type of charged pigment particle, a second type of charged pigment particle, a third type of charged pigment particle, and a fourth type of charged pigment particle. The color of each type of charged pigment particle is different from the colors of all other types of charged pigment particles.

17. The electro-optical display of claim 16, wherein, The electrophoretic medium also contains fifth type of charged pigment particles.

18. The electro-optical display of claim 16, wherein, The colors of the first, second, third, and fourth charged pigment particles are selected from white, black, yellow, cyan, magenta, green, blue, and red.

19. The electro-optical display of claim 16, wherein, The first type of charged pigment particles carries a negative charge, while the second, third, and fourth types of charged pigment particles carry a positive charge.

20. A method for manufacturing an electro-optical display, the method comprising the following steps: An aqueous dispersion of multiple microcapsules is provided, each of the multiple microcapsules containing an electrophoretic medium comprising multiple charged pigment particles and a nonpolar liquid; An aqueous binder solution or dispersion is mixed with an aqueous dispersion of multiple microcapsules to form an aqueous microcapsule slurry, wherein the binder solution or dispersion comprises a polymer containing one or more quaternary ammonium functional groups in its molecular structure. A first electrode layer including a light-transmitting electrode is provided, the first electrode layer having a surface; The aqueous microcapsule slurry is applied to the surface of the first electrode layer to form an aqueous microcapsule layer; The aqueous microcapsule layer is dried to form an electro-optic material layer on the first electrode layer; An adhesive composition is applied to an electro-optic material layer to form an adhesive layer, the electro-optic material layer being disposed between the first electrode layer and the adhesive layer; A release sheet is attached to the adhesive layer to form a front panel laminate, wherein the adhesive layer in the front panel laminate is disposed between the electro-optic material layer and the release sheet; Remove the release sheet to expose the adhesive layer; The backplate is attached to the exposed surface of the adhesive layer, the backplate including a second electrode layer.

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