TWI755081B - Electro-optic display and composite materials having low thermal sensitivity for use therein - Google Patents

Abstract

An electro-optic display includes a layer of electro-optic material, at least one conductor, and an adhesive material between the layer of electro-optic material and the at least one conductor. At least one of the electro-optic material and adhesive material comprises a composite material that includes a polymer phase and a filler phase, the filler phase having a conductivity greater than or equal to 0.5 X 10 ³S/m, a ratio of the coefficient of thermal expansion of the filler to the polymer is less than or equal to 0.5, and a concentration of the filler phase in the composite material is greater than or equal to a filler concentration corresponding to a conductivity transition point of the composite material.

Description

Electro-optic display and composite material with low thermal sensitivity therefor

The present invention relates to electro-optic displays and materials used therefor, especially composite materials. This invention relates in part to composite materials included in adhesives or adhesive compositions having electrical and other properties that make them particularly suitable for use in electro-optic displays.

Electro-optic displays contain a layer of electro-optic material. The term "electro-optic" as applied to a material or display is used herein in its conventional sense in the imaging arts to denote a material having at least one first and second display state with different optical properties, which is altered by the application of an electric field to the material. From its first to its second display state. While this optical property is typically color perceptible to the human eye, it can also be other optical properties such as optical transmittance, reflectance or brightness, or in the case of displays intended for machine reading, outside the visible range It can be false color in the sense of a change in reflectivity at electromagnetic wavelengths.

Some electro-optic materials are solid in the sense that their material has a solid outer surface, although the material can and often does have an interior space filled with a liquid or gas. Such displays using solid-state electro-optic materials may be referred to hereinafter as "solid-state electro-optic displays" for convenience. Thus, the term "solid state electro-optical display" includes rotating two-color component displays, encapsulated electrophoretic displays, microcellular electrophoretic displays, and encapsulated liquid crystal displays.

The terms "bistable" and "bistable" are used herein in their conventional senses in the art to refer to a display comprising display elements having at least one first and second state of differing optical properties, and such that After a given element has been driven to its hypothetical first or second display state by a finite-time addressing pulse, that state continues for at least several times the shortest addressing pulse time required to change the state of the display element after the addressing pulse has terminated , for example at least 4 times. US Patent No. 7,170,670 shows that some particle-based electrophoretic displays that can have gray scales are stable not only in their extreme black and white states, but also in their intermediate gray state, as do some other types of electro-optic displays. This type of display is suitably called "multi-stable" rather than bistable, although the term "bistable" may be used herein for convenience to cover both bistable and multi-stable displays.

Many types of electro-optic displays are known. One type of electro-optical display is of the rotating bichromatic component type, as described, for example, in US Pat. display, but the term "rotating bi-color member" is more accurate and preferable because in some of the above patents the rotating member is not a sphere). This display uses a large number of small bodies (generally spherical or cylindrical) having two or more parts with different optical characteristics, and inner even moments. These individuals are suspended in vacuoles within a liquid-filled matrix, which are filled with liquid allowing the individuals to rotate freely. The appearance of the display by applying an electric field to it, thus rotating the individual to various positions and changing the portion of the individual viewed through the viewing surface. This type of electro-optic medium is generally bistable.

Another type of electro-optic display uses an electrochromic medium, such as in the form of a nanochromic film, comprising an electrode formed at least in part from a semiconducting metal oxide, and a plurality of reversibly color-changing dyes attached to the electrode Molecules; see eg Nature 1991, 353 , 737 by O'Regan, B. et al; and Information Display, 18(3) , 24 (March 2002) by Wood, D.. See also Bach, U. et al. Adv. Mater., 2002, 14(11) , 845. Nanochromic films of this type are also disclosed in, eg, US Pat. Nos. 6,301,038, 6,870,657 and 6,950,220. This type of medium is also generally bistable.

Another type of electro-optic display is the electrowetting display developed by Philips and described in Hayes, R.A. et al. "Video-Speed Electronic Paper Based on Electrowetting", Nature, 425, 383-385 (2003). US Patent No. 7,420,549 shows that such electrowetting displays can be made bistable.

A type of electro-optic display is a particle-based electrophoretic medium, which has been the subject of intensive research and development over the years, in which a plurality of charged particles move through a fluid under the influence of an electric field. Compared with liquid crystal displays, electrophoretic displays can have the properties of good brightness and contrast, wide viewing angle, bi-stability, and low power consumption. Nonetheless, the long-term image quality issues of these monitors prevented them from being widely used. For example, the particles that make up electrophoretic displays tend to settle and result in undue service life of these displays.

As indicated above, the electrophoretic medium needs to be fluid. In most prior art electrophoretic media, this fluid is a liquid, but electrophoretic media can be made using gaseous fluids; see eg Kitamura, T. et al. "Electrical toner movement for electronic paper-like display", IDW Japan, 2001, Paper HCS1-1; and "Toner display using insulative particles charged triboelectrically" by Yamaguchi, Y. et al., IDW Japan, 2001, Paper AMD4-4. See also US Patent Nos. 7,321,459 and 7,236,291. When the medium is used in an orientation where sedimentation can occur, such as when the medium is arranged in a vertical plane, the gas-based electrophoretic medium is obviously prone to the same type of problems as the liquid-based electrophoretic medium due to particle settling. In fact, particle settling is clearly a more serious problem in gas-based electrophoretic media than in liquid systems, because the lower viscosity of gaseous suspension fluids compared to liquid ones results in faster settling of electrophoretic particles.

Numerous patents and applications assigned to or in the name of Massachusetts Institute of Technology (MIT), E Ink Corporation, E Ink California, LLC, and related companies disclose various methods for encapsulation and microelectrophoresis and other electro-optical media. Technology. The encapsulated electrophoretic medium comprises a number of small capsules, each of which itself comprises an inner phase containing electrophoretic mobile particles in a fluid medium, and a capsule wall surrounding the inner phase. Generally, the capsule itself is held within a polymeric binder to form a homogenous layer between the two electrodes. In a microcellular electrophoretic display, charged particles and fluids are not encapsulated within microcapsules, but are retained within a plurality of cavities formed within a carrier medium, typically a polymeric membrane. The technologies described in these patents and applications include: (a) Electrophoretic particles, fluids, and fluid additives; see, eg, US Pat. Nos. 7,002,728 and 7,679,814; (b) capsules, adhesives, and encapsulation methods; see, eg, US Pat. Nos. 6,922,276 and 7,411,719; (c) micelle structures, wall materials, and methods of forming micelles; see, eg, US Pat. Nos. 7,072,095 and 9,279,906; (d) methods of filling and sealing micelles; see, eg, US Pat. Nos. 7,144,942 and 7,715,088; (e) Films and subassemblies containing electro-optic materials; see, eg, US Pat. Nos. 6,982,178 and 7,839,564; (f) Backsheets, adhesive layers, and other auxiliary layers and methods for displays; see, eg, US Pat. Nos. D485,294; 6,124,851; 6,130,773; 6,177,921; 6,232,950; , 6,445,374,6,480,182,6,498,114,6,506,438,6,518,949,6,521,489,6,535,197,6,545,291,6,639,578,6,657,772,6,664,944,6,680,725; 6,683,333,6,724,519,6,750,473,6,816,147,6,819,471,6,825,068,6,831,769,6,842,167,6,842,279,6,842,657,6,865,010,6,873,452,6,909,532 , 6,967,640,6,980,196,7,012,735,7,030,412,7,075,703,7,106,296,7,110,163,7,116,318,7,148,128,7,167,155,7,173,752,7,176,880,7,190,008,7,206,119,7,223,672,7,230,751,7,256,766,7,259,744,7,280,094,7,301,693,7,304,780,7,327,511,7,347,957,7,349,148,7,352,353 , 7,365,394,7,365,733,7,382,363,7,388,572,7,401,758,7,442,587,7,492,497,7,535,624,7,551,346,7,554,712,7,583,427,7,598,173,7,605,799,7,636,191,7,649,674,7,667,886,7,672,040,7,688,497,7,733,335,7,785,988,7,830,592,7,843,626,7,859,637,7,880,958,7,893,435 , 7,898,717, 7,905,977, 7,957,053, 7,986,450, 8,009,344, 8,027,081, 8,049,947, 8,072,675, 8,077,141, 8,089 , 453,8,120,836,8,159,636,8,208,193,8,237,892,8,238,021,8,362,488,8,373,211,8,389,381,8,395,836,8,437,069,8,441,414,8,456,589,8,498,042,8,514,168,8,547,628,8,576,162,8,610,988,8,714,780,8,728,266,8,743,077,8,754,859,8,797,258,8,797,633,8,797,636 , 8,830,560,8,891,155,8,969,886,9,147,364,9,025,234,9,025,238,9,030,374,9,140,952,9,152,003,9,152,004,9,201,279,9,223,164,9,285,648, and No. 9,310,661; and US Patent application Publication No. 2002 / 0060321,2004 / 0008179,2004 / 0085619, 2004/0105036, 2004 / 0112525,2005/0122306,2005/0122563,2006/022,2009,2005,2009,2008/09748/2007/0109219,2008/109/0109/08/2008/2008,2008/109/2008/2008/2008/2008/2009/2008/20089,2009/2009/0122389,2009 / 0315044, 2010/0177396, 2011/0187683, 2011/0187689, 2011/0297, 2013/0278900, 2014/007802401, 014/014/014/2014, 2014/0368753, 2014/0376164, 2015/0171112, 2015/0205178, 2015/02226986, 2015/0227018/015/2017, /0187759; and International Patent Application Publication No. WO 00/38000, European Patent Nos. 1,099,207 B1 and 1,145,072 B1; (g) color formation and color adjustment; see, eg, US Pat. Nos. 7,075,502 and 7,839,564; (h) A method of driving a display; see, eg, US Pat. Nos. 7,012,600 and 7,453,445; (i) Display applications; see, eg, US Pat. Nos. 7,312,784 and 8,009,348; and (j) Non-electrophoretic displays, as disclosed in US Patent No. 6,241,921 and US Patent Application Publication No. 2015/0277160; and packaging and cell technology applications other than displays; see, eg, US Patent Application Publication No. 2015/0005720 and No. 2016/0012710.

Many of the aforementioned patents and applications suggest that the walls surrounding the separating microcapsules in an encapsulated electrophoretic medium can be replaced by a continuous phase, thus producing so-called polymer dispersed electrophoretic displays, wherein the electrophoretic medium comprises a plurality of separated droplets of electrophoretic fluid, and The polymeric material is a continuous phase, and within this polymer dispersed electrophoretic display the electrophoretic fluid separated droplets can be considered capsules or microcapsules, even though there is no separate capsule membrane bound to each individual droplet; see, eg, the aforementioned US Pat. No. 6,866,760. Thus, for the purposes of this application, such polymer-dispersed electrophoretic media are considered a subspecies of encapsulated electrophoretic media.

While electrophoretic media are often opaque (because, for example, in many types of electrophoretic media, the particles substantially block visible light from penetrating the display) and operate in a reflective mode, many types of electrophoretic displays can be operated in a so-called "shutter mode", where one display The state is substantially opaque and the other is light transmissive. See, eg, US Patent Nos. 5,872,552, 6,130,774, 6,144,361, 6,172,798, 6,271,823, 6,225,971, and 6,184,856. A dielectrophoretic display that resembles an electrophoretic display but relies on changes in electric field strength can operate in a similar mode; see US Pat. No. 4,418,346. Other types of electro-optical displays can also operate in shutter mode. Electro-optic media operating in shutter mode can be used in multilayer structures for full-color displays; in such structures, at least one layer adjacent to the viewing surface of the display operates in shutter mode to expose or hide a second layer further from the viewing surface.

Packaged electrophoretic displays generally do not suffer from the clustering and settling failure modes of traditional electrophoretic devices and offer further advantages, such as the ability to print or coat displays on a wide variety of flexible and rigid substrates. (The use of the word "printing" is intended to include all forms of printing and coating including, but not limited to: pre-meter coating such as patch die coating, slot or extrusion coating, slip or tandem coating, Curtain coating; Roll coating such as doctor roll coating, front and back roll coating; Gravure coating; Dip coating; Spray coating; Bending coating; Spin coating; Brush coating ; air knife coating; screen printing; electrostatic printing; thermal printing; ink jet printing; electrophoretic deposition (see US Pat. No. 7,339,715); and other similar techniques.) Thus, the resulting displays can be flexible sex. Furthermore, because the display medium can be printed (using various methods), the display itself can be inexpensively manufactured.

An electrophoretic display generally includes a layer of electrophoretic material, and at least two other layers disposed on opposite sides of the electrophoretic material, one of the two other layers being an electrode layer. In most such displays, both layers are electrode layers, and one or both of the electrode layers are patterned to define display pixels. For example, one electrode layer can be patterned as elongated column electrodes and another layer as elongated row electrodes running at right angles to the column electrodes, the pixel being defined by the intersection of the row and column electrodes. Alternatively and more commonly, one electrode layer is in the form of a single continuous electrode, and the other electrode layer is patterned into a matrix of pixel electrodes, each of which defines a pixel of the display. In another type of electrophoretic display intended for use with a stylus, the print head or similar movable electrodes are separate from the display and only one layer adjacent to the electrophoretic layer contains the electrodes, the layer on the opposite side of the electrophoretic layer is generally intended to prevent damage to the movable electrodes The protective layer of the electrophoretic layer.

Manufacturing a three-layer electrophoretic display typically involves at least one build-up operation. For example, many of the aforementioned MIT and E Ink patents and applications describe a method of making an encapsulated electrophoretic display in which an encapsulated electrophoretic medium comprising an encapsulated in an adhesive is coated with a conductive material comprising indium tin oxide (ITO) or similar A flexible coating (as one electrode of the final display) is applied to a flexible substrate on a plastic film, and the capsule/adhesive coating is dried to form a homogenous layer of electrophoretic medium firmly adhering to the substrate. A backplane containing an array of pixel electrodes, and an appropriate arrangement of conductors connecting the pixel electrodes to the driver circuit, is prepared, respectively. To form the final display, the substrate with the capsule/adhesive layer thereon is laminated to the backplane using a lamination adhesive. (By replacing the backplate with a simple protective layer over which a stylus or other movable electrode can slide, such as a plastic film, which can be prepared using a very similar method for a stylus or similar movable electrode Electrophoretic display.) In a preferred form of this method, the backplane itself is flexible, and is prepared by printing the pixel electrodes and conductors on a plastic film or other flexible substrate. A well-defined lamination technique whereby displays are mass-manufactured in this way is roll lamination using lamination adhesives.

The electro-optic display manufactured using the above-mentioned front plate laminate or double-sided release film usually has a layer of laminated adhesive between the electro-optic layer itself and the back plate, and the existence of the laminated adhesive layer affects the electro-optic characteristics of the display. In particular, the conductivity of the build-up adhesive layer affects the low temperature performance and resolution of the display. The low temperature performance of the display can be (now demonstrated) improved by increasing the conductivity of the build-up adhesion layer, such as doping the layer with tetrabutylammonium hexafluorophosphate or other materials, as described in the aforementioned US Pat. Nos. 7,012,735 and 7,173,752. However, increasing the conductivity of the build-up adhesive layer in this way tends to increase pixel smear (the phenomenon in which the area of the electro-optic layer that changes its optical state in response to changes in pixel electrode voltage is larger than the pixel electrode itself), and this smear tends to reduce the display resolution. Therefore, this type of display obviously has to compromise between low temperature performance and display resolution, and in practice, it usually sacrifices low temperature performance. Furthermore, because the conductivity of the build-up adhesive is temperature dependent, the temperature range over which the display can acceptably function is limited to a narrow temperature range. This limits the possible applications of the display to environments that do not experience large temperature swings.

Accordingly, there is a need for improved build-up adhesive compositions and other composite materials that provide improved performance for electrophoretic displays over a wide ambient temperature range.

A first embodiment of the present invention provides an electro-optic display comprising a layer of electro-optic material, at least one conductor, and an adhesive material between the layer of electro-optic material and the at least one conductor. At least one of the electro-optical material and the adhesive material comprises a composite material containing a polymer phase and a filler phase such that the volume ratio of the filler phase is approximately a critical value for percolation. In addition, the electrical conductivity of the filler phase may be greater than or equal to 0.5 X 10 ³ S/m, the ratio of the thermal expansion coefficient of the filler to the polymer may be less than or equal to 0.5, and the concentration of the filler phase in the composite material may be greater than or equal to the corresponding composite material The filler concentration at the conductivity transition point.

The composite materials of various embodiments of the present invention are well suited for particle-based electrophoretic displays. However, the composite material can also be used in other types of electro-optic displays, such as displays utilizing polymer dispersed liquid crystals.

These and other aspects of the present invention will be apparent from the following description.

In the following detailed description, numerous specific details are exemplified in order to provide a thorough understanding of the related teachings. However, it will be apparent to those skilled in the art that these teachings may be practiced without such detail.

In a typical method of fabricating an electro-optic display, two sub-assemblies are first fabricated, one sub-assembly comprising the electro-optic layer and the first substrate, and the second comprising the second substrate; at least one of the sub-assemblies and generally both Contains electrodes. Also in one common form of method for making active matrix displays, a subassembly includes a substrate, a single continuous ("common") electrode (which extends across multiple pixels, typically the entire display), and an electro-optic layer, and The second assembly (commonly referred to as the "backplane") includes a substrate carrying a matrix of pixel electrodes that define individual pixels of the display, and a substrate used to generate the potential energy for the pixel electrodes necessary to drive the display (ie, to switch each pixel to the display on the display). Non-linear devices (usually thin film transistors) and other circuits that provide the optical state required for the desired image. A build-up adhesive is provided between the first and second subassemblies, which are adhered together to form the final display.

Referring to Figure 1 of the accompanying drawings, a preferred lamination method of the present invention is now disclosed, albeit by way of example only, which is a schematic cross-sectional view through a sub-assembly (front plate laminate, or FPL) used in the method of the present invention , this assembly includes a substrate, a conductive layer, an electro-optical layer, and an adhesive layer, and the sub-assembly described in the intermediate stage of the method of the present invention before this assembly is laminated to the second assembly.

The front plate laminate shown in Figure 1 (generally shown as 100) comprises a light transmissive substrate 110, a light transmissive electrode layer 120 (it should be noted that these are not electrodes on the opposite side of the electro-optic layer of the build-up adhesive in the final electro-optic display) , the electro-optic layer 130, the build-up adhesive layer 180, and the release liner 190; the release liner is described in this method as being removed from the build-up adhesive layer 180 prior to laminating the FPL 100 to the backplane.

The substrate 110 is generally a transparent plastic film, such as a 7 mil (177 micron) poly(ethylene terephthalate) (PET) sheet. The lower surface of substrate 110 (FIG. 1) that forms the viewing surface of the final display may have one or more additional layers (not shown), such as protective layers to absorb ultraviolet radiation, barrier layers to prevent intrusion of oxygen or moisture into the final display, and Anti-reflective coatings to improve the optical properties of displays. A thin light-transmitting conductive layer 120 is coated on the upper surface of the substrate 110, which is preferably ITO, and serves as a common front electrode for the final display. PET films coated with ITO are commercially available.

Electro-optic layer 130 may be deposited on conductive layer 120, typically by slot coating, with electrical contact between the two layers. The electro-optic layer 130 shown in FIG. 1 is an encapsulated electrophoretic medium and includes microcapsules 140 each including negatively charged white particles 150 and positively charged black particles 160 in a hydrocarbon-based fluid 165 . Microcapsules 140 are retained within polymeric binder 170 . When an electric field is applied across the electro-optic layer 130, the white particles 150 move toward the positive electrode and the black particles 160 move toward the negative electrode, so that depending on whether the conductive layer 120 is positive or negative with respect to the adjacent pixel electrodes in the backplane, the electro-optic layer 130 pair passes through the substrate. 110 The viewer looking at the display appears white or black. As understood by those skilled in the art, the charged particles (150, 160) are not limited to black and white, and can be any color.

The FPL 100 is desirably formed by coating the build-up adhesive 180 in liquid form on the release sheet 190 by slot coating, drying (or curing) the adhesive to form a solid layer, and then applying the adhesive to the release sheet 190. It is prepared by laminating the release sheet to the electro-optic layer 130 which has been previously coated on the substrate 110 carrying the conductive layer 120; this lamination can be conveniently carried out using a thermal roll lamination method. (Alternatively, but less desirable, a build-up adhesive can be applied to the electro-optic layer 130, then dried or cured and covered with a release liner 190.) The release liner 190 is conveniently a 7 mil (177 micron) film; as used Depending on the nature of the electro-optic medium, it will be desirable to coat the film with a release agent such as polysiloxane. As depicted in FIG. 1 , release sheet 190 is stripped or removed from build-up adhesive 180 prior to lamination of FPL 100 to a backplane (not shown) to form the final display.

The front plate laminate 100 is depicted in FIG. 1 in a general form that can be used in all areas of the present invention. The adhesion layer 180 incorporated into the FPL 100 may comprise a composite material with low thermal sensitivity, as described in detail below.

Further details regarding front plate laminates, methods of making and using them are disclosed in the aforementioned US Patent No. 6,982,178, and US Patent Application Publication No. 2009/0225397, the entire contents of which are incorporated herein by reference.

A double-sided release sheet (generally shown as 300 ) according to another embodiment of the present invention is shown in FIG. 2 of the accompanying drawings. The double-sided release liner 300 comprises a central layer 302 of electro-optic material, particularly in FIG. 2 the layer comprising pockets 304 in a polymeric binder 306 . The bladder 304 is similar to that described above with respect to FIG. 1 . Sheet 300 further includes a first adhesive layer 308, a first release sheet 310 covering the first adhesive layer 308, a second adhesive layer 312 disposed on the opposite side of the layer 302 from the first adhesive layer 308, and covering the second adhesive The second release sheet 314 of the layer 312 is formed.

Sheet 300 may be formed by first coating release liner 310 with a layer of adhesive and then drying or curing it to form first adhesive layer 308 . Next, the mixture of bladder 304 and adhesive 306 is printed or deposited on first adhesive layer 308 , and then the mixture is dried or cured to form homogenous layer 302 . Finally, a layer of adhesive is deposited on the layer 302 , dried or cured to form a second adhesive layer 312 , and covered with a second release sheet 314 .

This sequence of operations to form sheet 300 is suitable for continuous manufacturing, and by careful selection of materials and process conditions a complete sequence of operations can be performed in a single pass through conventional roll-to-roll coating equipment, which is useful to those skilled in the art of coating technology. understandable.

To assemble a display using a double-sided release film, such as film 300, one release sheet (typically the one to which the electro-optic material is applied) is peeled off, and the rest are laminated using, for example, thermal, radiation, or chemical-based lamination methods. A double-sided release film layer is attached to the front substrate. In general, the front substrate includes a conductive layer that forms the electrodes prior to the final display. The front substrate may include additional layers, such as UV filter layers, or protective layers intended to protect the conductive layers from mechanical damage. The other release liner is then peeled off, thereby exposing the second adhesive layer, which is used to attach the electro-optic material coating assembly to the backsheet. Again, thermal, radiation, or chemical based lamination methods can be used. It should be understood that the order of the two lamination methods is essentially arbitrary and can be reversed, although in practice the double-sided release film is laminated to the front substrate first, and then the resulting previous assembly is laminated to the backplane, almost always. is more convenient.

Further details regarding double-sided release films, methods of making and uses thereof are disclosed in US Patent Application Publication No. 2004/0155857, the contents of which are incorporated herein by reference in their entirety.

Either or both of the adhesive layers 308 and 312 may comprise a composite material comprising a polymer phase and a filler phase. The filler phase concentrations are chosen such that the conductivity of the composite system exhibits a low temperature dependence in the temperature range relevant to the operation of the display.

The filler phase of the polymer phase added to the composite system is preferably more conductive than the polymer phase, such that adding more filler to the polymer phase increases the conductivity of the composite. Furthermore, it is preferred that the coefficient of thermal expansion (CTE) of the filler is substantially smaller than that of the polymer composite. For example, composites can be provided that contain polyurethane as the polymer phase, and metal needles or chips such as aluminum or nickel. The CTE of the polyurethane may range from 60 to 200 ppm/K. The CTE of aluminum is about 22 ppm/K. The CTE of nickel is about 13 ppm/K. The ratio of the CTE of the filler phase to the CTE of the polymer phase is preferably 0.5 or less, more preferably 0.3 or less, and most preferably 0.1 or less.

In order to suppress the temperature effect of the conductivity of the composite, fillers were added to the composite in an amount about the percolation threshold. The term "percolation threshold" used throughout the specification and the scope of the claims refers to the filler volume ratio in a composite containing a polymer phase and a filler phase, below which the logarithm of the conductivity of the composite is closer to that of the polymer phase The log of the conductivity of the non-filler phase, above which the log of the composite conductivity is closer to the log of the conductivity of the filler phase than the polymer phase.

The conductivity of the composite was constrained to ensure that the filler-to-volume ratio in the polymeric matrix was approximately the percolation threshold, despite large temperature swings. Reference is made to Figure 5, which provides a representative plot of polymer composite conductivity (y-axis) versus filler volume ratio in polymer composites (x-axis). Point 400 in the plot is the percolation threshold.

If the thermal expansion coefficient of the polymer phase in the composite is much larger than that of the filler, the volume ratio of the filler phase in the composite decreases with increasing temperature. For example, if the initial volume ratio φ of filler in the composite is about the percolation threshold (400), the composite conductivity decreases substantially with increasing temperature because the filler concentration decreases. This would go against the natural tendency to increase the high temperature conductivity of the unfilled polymer matrix. As the temperature cools, the polymer phase shrinks more than the filler causing the filler volume ratio to increase. Therefore, if the initial volume ratio of filler in the composite is about the percolation threshold (400), the conductivity of the composite increases with decreasing temperature.

Thus, incorporating a filler with a coefficient of thermal expansion substantially less than the polymer phase into the composite, and loading the composite with a filler about the percolation threshold, reduces the ratio of the change in conductivity with temperature effect, which is higher for the unfilled Polymer material representation. In other words, the tendency for the conductivity to increase with increasing temperature and to decrease with decreasing temperature is reduced. Composite materials in accordance with various embodiments of the present invention can provide materials with far less variation in conductivity change ratios than would be obtained using unfilled polymers over a temperature range of interest.

The phrase "about the percolation threshold" used throughout the specification and claims means that the filler concentration (volume percent) is at or above the conductivity transition point. The conductivity transition point can be calculated from the conductivity curve of the composite material, as provided by the plots in Figures 5 and 6 . Referring to Figure 6, a first line y1 is drawn through the point on the conductivity curve where the composite material is at zero filler concentration, the slope m1 of line y1 is equal to the slope of the conductivity curve at zero filler concentration. A second line y2 is drawn through the point on the conductivity curve corresponding to the percolation threshold, and the slope m2 of the line y2 is equal to the slope of the conductivity curve at the percolation threshold. The intersection 402 of the two lines y1 and y2 in FIG. 6 provides a conductivity transition point. The filler concentration at the conductivity transition point can be calculated using the following equations (1) and (2) for y1 and y2: y1=m1*(φ)+b1 Equation 1

y2=m2*(φ)+b2 Equation 2

At the conductivity transition point, y1 is equal to y2, so: m1*(φ)+b1=m2*(φ)+b2

Solving for "φ" provides Equation 3: φ=(b2-b1)/(m1-m2) Equation 3

Thus, the filler concentration at the conductivity transition point is equal to the ratio of the y-intercept difference between y2 and y1 to the difference in slope between y1 and y2.

Preferably, the composite materials used in the various embodiments of the present invention exhibit a rate of change in conductivity with temperature, i.e., (1/s)*ds/dT, which is less than or equal to the change in conductivity with temperature for unfilled polymers 60% of the rate, more preferably less than or equal to 30%, most preferably less than or equal to 10%.

When incorporating the composite into an adhesive layer of an electro-optic display, the polymer ratio of the composite material according to various embodiments of the present invention preferably has a greater conductivity in the direction from the electrode to the electro-optic material than in this layer. Anisotropic build-up adhesive in plane. This anisotropic adhesive produces only a small voltage drop between the electrodes and the electro-optic material (so the electric field across the electro-optic material layer can be as large as possible), while still being highly resistive to current flow between adjacent electrodes, thus making the display Crosstalk between adjacent pixels is minimized.

The build-up adhesive can be a hot melt adhesive, but can also be a thermoset, radiation curable, or pressure sensitive adhesive. The adhesive can be based on ethylene vinyl acetate, acrylic, polyolefin, polyamide, polyester, polyurethane, polysiloxane, epoxy, polyvinyl butyrate, polystyrene Ethylene-butadiene, or vinyl monomers or oligomers. To provide the desired degree of anisotropic conductivity, the adhesive may be loaded with conductive particles, such as carbon particles, silver particles, coated polymer spheres, coated glass spheres, indium tin oxide particles, or nanophase Indium tin oxide particles. Alternatively, conductive polymers, such as polyacetylene, polyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene) (PEDOT), or polythiophene, can be used to doped the polymer such that it is Conduction is good in the axial direction (perpendicular to the adhesion layer thickness), but not in the plane of this layer. To make these films, an adhesive sheet can be cast and then mono- or biaxially stretched to introduce the desired degree of anisotropic conductivity. Various types of anisotropic adhesives are described in US Pat. Nos. 6,365,949, 5,213,715, and 4,613,351, and anisotropic adhesives are commercially available, for example, from Minnesota Mining and Manufacturing Corporation ("3M"), Henkel Loctite Corporation, 1001 Trout Brook Crossing, Rocky Hill CT 06067, Btech Corporation, 8395 Greenwood Drive, Longmont CO 80503, and Dana Enterprises International, 43006 Osgood Road, Fremont CA 94539.

It is generally preferred that the anisotropic adhesives used in various embodiments of the present invention have a conductivity in the plane of the adhesive layer of less than about ^10-10 S/cm and a conductivity in the z-axis direction of greater than about 10 ^-9 S/cm.

A method of forming a composite material in accordance with an embodiment of the present invention is also provided. The composite material may be provided in the form of an anisotropic adhesive layer having a greater conductivity perpendicular to the plane of the layers than in the parallel direction. The method comprises dispersing in an adhesive matrix a plurality of conductive filler particles, the particles having a different conductivity than the matrix; applying an electric or magnetic field effective to cause the particles to form a bundle of conductive strands extending substantially perpendicular to the plane of the layer, in the particle/matrix mixture; and increasing the viscosity of the matrix (generally by gelling or curing the matrix) to prevent the particles from moving away from the strand.

The fabrication of anisotropic conductive films using electrorheological and magnetorheological effects by the method of the present invention is described in a highly schematic manner in Figures 3A and 3B of the accompanying drawings. The electrorheological (ER) effect is the effect of applying an electric field across a dispersion of particles, such as a dispersion contained between electrodes in parallel plates, causing the particles that make up the dispersion to form strands or needle-like agglomerates. As shown in FIG. 3A , the process begins by forming a layer of conductive particles 12 dispersed in a matrix (continuous phase) of a laminate adhesive 14 . An electric or magnetic field is applied perpendicular to the plane of the layer, thereby causing particles 12 to form bundles 16 extending through the thickness of the layer, as depicted in Figure 3B. Finally, the viscosity of the matrix 14 is substantially increased, typically by gelling or curing the matrix, to prevent further movement of the particles 12 through the matrix 14, thus locking the strands 16 in place.

Bundles of parallel electric field lines are generated when the composite conductivity (k*) of the particles is significantly greater than that of the matrix. In a preferred method of the present invention, the precursor binder (as shown in FIG. 3A ) consists of particles with relatively high conductivity (k _p >10 ^-9 S/cm) dispersed in particles with low conductivity (k _m < 10 ^-11 S/cm) in a matrix. The particles are aligned in the z-axis direction by applying an electric field across the dispersion, and the resulting z-axis beams are locked in place by solidifying or gelling the matrix. The final adhesive film then contains the conductive strands that span or percolate only in the z-axis direction, since the strands are laterally spaced and thus separated by the low conductivity matrix. The z-axis conductivity would be dominated by the bundle conductivity, and thus by the particle conductivity, while the transverse conductivity would be dominated by the continuous low conductivity matrix.

This method is particularly suitable for making continuous films of z-axis lamination adhesives. For example, continuous films of z-axis conductive adhesives can be formed by feeding a fully mixed dispersion of conductive particles in a low-conductivity adhesive matrix into a coating die, and coating the dispersion into a thin film, typically 10- 100 microns thick, followed by applying an electric field and curing or gelling.

The magnetorheological method for making z-axis conductive adhesives is similar to the electrorheological method; magnetic particles are dispersed in a non-magnetic adhesive matrix, the particles are arranged in bundles in the z-axis direction due to the application of a magnetic field, and the bundles are arranged by applying a magnetic field to the matrix. Cured or gelled and locked in place. In this case, the particles must be magnetically polarizable and have a conductivity within the above range, typically greater than ^10-9 S/cm. The range of particles that meet the requirements of these magnetorheological methods may be more limited than the range of particles suitable for use in electrorheological methods, but magnetorheological methods are preferred because applying a magnetic field across the layer does not require electrical contact with the layer surface, Thus, an aqueous adhesive matrix can be used, which is generally not the case with electrorheological methods.

In the electrorheological method for producing a composite material containing a laminated adhesive composition as a polymer matrix, the conductivity of the conductive particles as fillers may preferably be not less than 0.5 X 10 ^-9 S/cm, 0.5 X 10 ^-7 S /m, 0.5 X 10 ^-5 S/m, 0.5 X 10 ^-3 S/m, 0.5 X 10 ^-1 S/m, 5 S/m, 0.5 X 10 ³ S/m, 0.5 X 10 ⁵ S/m , 0.5 X 10 ⁶ S/m, 10 X 10 ⁶ S/m, and 20 X 10 ⁶ S/m, the preferred degree of which is increased in the order shown above, and the diameter is not greater than about 1/1 of the final film thickness 10. (The term "diameter" is used herein to include the well-known "equivalent diameter" of an aspherical particle, ie, the diameter of a spherical particle having the same volume as the aspherical particle.) The particle may be formed from a semiconducting polymer, such as acid doped Polyaniline, polythiophene, and pyrolyzed polyacrylonitrile. The particles may be formed from low-k* materials that are "activated" (increased) to higher k* (relative to the matrix) by the addition of trace amounts of polar materials, such as water or ethylene glycol, that are primarily adsorbed on the particle surface . Suitable low-k* materials include cellulosic materials and various aluminas, silicates and zeolites. The conductivity of the matrix (continuous phase) should be low relative to the particles, and this low conductivity is preferably less than 10 ^-10 S/cm. Many low conductivity, low viscosity oils, such as hydrocarbons as fluids in many encapsulated electrophoretic media, are suitable; however, the matrix must also behave as an adhesive and be gelable or curable. Locked in the z-axis bundle formed by this method. For example thermally reversible gelling materials such as Kraton (registered trademark) rubber (block copolymer) or polyurethane are particularly advantageous as the continuous phase, which can be used alone or in combination with diluents to reduce viscosity for coating and particle alignment . Typical non-aqueous pressure sensitive adhesives, such as polyacrylate solutions, or succinic acid functionalized hydrocarbon polymers, such as ethylene propylene copolymers, or silicone rubber-type adhesives can also be used. For gelled substrates, coating and particle alignment occurs without the material being gelled, and then the substrate is gelled after strand formation, for example by lowering the temperature, or by adding or removing chemicals or reactants or exposing Under UV light source, the matrix is cross-linked. For solvent-based non-aqueous adhesives, the strands can be locked in place by rapidly evaporating the solvent.

The magnetorheological method of the present invention can use any of the above-discussed substrates, since the magnetorheological method differs from the electrorheological method only in that the wire bundles are formed by magnetic field alignment rather than electric field alignment. However, because magnetorheological methods can utilize both aqueous and non-aqueous matrices, polyurethane adhesives, gelatin, or other aqueous continuous phases can also be used. Particles suitable for use in magnetorheological methods include iron and other magnetizable materials such as nickel and iron carbonyl; these materials are usually supplied in particle sizes greater than 1-10 microns, which may not be optimal for making adhesive films, but are can be ground to smaller sizes for use in the method of the present invention. Iron oxide, such as the γ _{- Fe2O3} material used in the magnetic recording industry, is typically supplied in much smaller particle sizes, on the order of 10-100 nm, and can thus be used for thin film preparation as supplied.

The particle criteria used in the magnetorheological method of the present invention are slightly different from most other magnetorheological particle applications. The present method does not require strong saturation magnetization, which is a typical criterion for the selection of particles for magnetorheological fluids, but in the present method the conductivity of the particles should be sufficient to meet the z-axis conductivity ranges listed above.

Laminated adhesive films containing the composites described above can then be laminated to electro-optical materials and finally to the active matrix backplane while maintaining the anisotropic conductivity of the adhesive, since the films are never subjected to large scale during the lamination process. Scale flow (relative to harness length).

Any anisotropic z-axis conductive adhesive based on bundles of conductive strands, or similar conductive regions within an intrinsically non-conductive matrix, should be experience a substantially uniform or homogeneous electric field over its entire area) with sufficient strands or areas of conductivity, otherwise undesired optical effects can occur. The bundle density per unit area can be adjusted, for example, by changing the size of the conductive particles, the volume ratio of the conductive particles, and the intensity and duration of the alignment field, thereby changing the microstructure of the anisotropic adhesive.

There are many types of build-up methods for manufacturing electrophoresis devices, including batch unit operations. A preferred method of this type is depicted in Figure 4 of the accompanying drawings in a highly schematic and side view. As shown in this figure, the method forms a display by converging two webs 202 and 204 . The web 202 contains the rear electrode assembly on the flexible substrate, although the individual components are not shown in FIG. 4 . Similarly, the web 204 includes a flexible substrate, a transparent electrode layer (eg, an ITO layer), and a dry film of bladder and adhesive, although again the individual components are not shown in FIG. 4 . As shown in FIG. 4, the web 202 is unwound from the feed tray 206 and brought under the coating die 208 with the electrode side up and down to apply a thin layer of radiation curable build-up adhesive 210. The adhesive 210 can be cured, for example, by visible light, ultraviolet light, or electron beam radiation. The web 202 carrying the adhesive 210 passes through a radiation source 212 , the intensity of which is adjusted for the catalyst concentration (and thus the cure rate) of the adhesive 210 and the speed of the web 202 . (If an anisotropic adhesive is used, electrical or magnetic heads may be provided between the coating die 208 and the radiation source 212 to form the desired strands of conductive particles prior to curing or gelling the substrate by the radiation source 212. )

The webs 204 are unwound from the feed pan 214 and the dried bladder-containing layer is brought to a convergence point 216 where the webs 202 and 204 are united. At this point of convergence 216, the radiation curable resin 210 is still in liquid form and readily fills the pores on the surface of the capsule-containing layer. The combination of web speed, catalyst concentration, and radiation intensity is adjusted to provide a cure rate at which hardening occurs after convergence point 216, and rollers 218 hold the two webs 202 and 204 together. Finally, the produced laminate web 220 is wound on a take-up disk 222 .

It can be seen that the above method allows the build-up method to operate in-line, thus resulting in a higher production rate than the batch unit method discussed previously.

In another embodiment of the present invention, the composite material can be incorporated into the electro-optic material layer of the display. In particular, the composite material can be incorporated into the adhesive of the encapsulating medium, or the polymeric film used to form the micelles. Some adhesives or polymeric film materials exhibit volume resistivity changes of more than 2 single digits when the temperature and humidity of their environment change within the range of 10-50°C and 10-90% relative humidity (RH). For satisfactory performance, it has now been found that the volume resistivity of the adhesive/film material is in the range of 10 to 90% RH and 10 to 50°C, or any wider RH and temperature range in which the display is intended to be operated Should not change more than about 10 times. It is desirable that the volume resistivity does not change by more than about 3 times, and preferably not more than about 2 times, over the specified RH and temperature ranges.

To limit the thermal sensitivity of the adhesive/film material to temperature and RH, it is possible to incorporate fillers into the adhesive/film material to provide composites similar to those described above. Incorporation of a conductive filler around the percolation threshold into a polymeric matrix with a coefficient of thermal expansion greater than that of the filler similarly limits temperature effects on the resistivity of the adhesive/film. For example, with increasing temperature, the expansion rate of the polymer phase is greater than that of the filler phase. If the volume ratio of the filler phase is about the percolation critical value, the resistivity of the composite decreases with increasing temperature. When the temperature is lowered, the polymer phase shrinks at a higher rate resulting in an increase in the filler volume ratio, which in turn reduces the resistivity of the composite. Thus, composites according to various embodiments of the present invention can provide adhesives/films with low thermal sensitivity compared to adhesives/films without any fillers.

Examples of acceptable binder materials include, but are not limited to, aromatic-free aliphatic polyurethanes such as NeoResin R 9630, NeoResin R 9330, NeoResin R 9314, NeoResin R 9314, NeoResin 9621, and mixtures thereof. It is preferred that the volume resistivity of the adhesive, measured at 10°C, does not change by a factor of more than 3 after 1000 hours at 25°C and 45% relative humidity. The phrase "maintain" is deliberately used to emphasize that when testing an adhesive to determine whether it meets the requirements of this aspect of the invention, care should be taken to ensure that the adhesive material does equilibrate with the specified atmosphere within a reasonable time. If a thick layer of adhesive material is tested, it may not equilibrate with the specified atmosphere for a considerable period of time and may get misleading results. This misleading result can be avoided by continuously testing thinner layers of adhesive material and checking for consistency. For sufficiently thin layers, it is sufficient to store the adhesive material only under the specified conditions for the specified time.

When testing the volume resistivity of a material as a function of RH and temperature, the same considerations discussed above should be observed to ensure that the sample being tested is truly in equilibrium with the atmosphere at the desired RH and temperature prior to measuring the volume resistivity.

Polymeric materials that can be used to form micelles include thermoplastics, thermosets, or precursors thereof. Examples of thermoplastic or thermoset precursors may include, but are not limited to, multifunctional acrylates or methacrylates, multifunctional vinyl ethers, multifunctional epoxides, and oligomers or polymers thereof. Crosslinkable oligomers that impart flexibility, such as urethane acrylates or polyester acrylates, can also be added to improve the resistance to flexing of the imprinted cells.

Further imprintable compositions for micelles may comprise polar oligomeric or polymeric materials. The polar oligomeric or polymeric material may be selected from the group consisting of oligomers or polymers having at least one of the following groups, such as nitro (--NO ₂ ), hydroxyl (--OH), carboxyl (--COO), alkoxy (--OR, where R is alkyl), halo (eg fluorine, chlorine, bromine, or iodine), cyano (--CN), sulfonic acid (--SO ₃ ) etc. The glass transition temperature of the polar polymeric material is preferably below 100°C, and more preferably below about 60°C. Designated examples of suitable polar oligomeric or polymeric materials may include, but are not limited to, polyhydroxy-functionalized polyester acrylates (eg, BDE 1025, Bomar Specialties Co, Winsted, Connecticut), or alkoxylated acrylates, such as ethyl acetate. Oxidized nonyl acrylate (eg, SR504, Sartomer Company), ethoxylated trimethylolpropane triacrylate (eg, SR9035, Sartomer Company), or ethoxylated pentaerythritol tetraacrylate (eg, SR494, available from Sartomer Company).

-9-酮(2-isopropyl-9H-thioxanthen-9-one)、4-苯甲醯基-4’-甲基二苯基硫化物、與1-羥基環己基苯基酮、2-羥基-2-甲基-1-苯基-丙-1-酮、1-[4-(2-羥基乙氧基)-苯基]-2-羥基-2-甲基-1-丙-1-酮、2,2-二甲氧基-1,2-二苯基乙-1-酮、或2-甲基-1[4-(甲硫基)苯基]-2-嗎啉基丙-1-酮。合適的模離型劑可包括但不限於經有機修改的聚矽氧共聚物，如聚矽氧丙烯酸酯(例如得自Cytec之Ebercryl 1360或Ebercyl 350)、聚矽氧聚醚(例如得自Momentive之Silwet 7200、Silwet 7210、Silwet 7220、Silwet 7230、Silwet 7500、Silwet 7600、或Silwet 7607)。該組成物可進一步視情況包含一種或以上的以下成分：共引發劑、單官能基UV固化性成分、多官能基UV固化性成分、或安定劑。Another type of imprintable composition used to form micelles comprises (a) at least one difunctional UV curable ingredient, (b) at least one photoinitiator, and (c) at least one mold release agent. Suitable difunctional components have molecular weights greater than about 200. Difunctional acrylates are preferred, and difunctional acrylates having a urethane or ethoxylated backbone are particularly preferred. More specifically, suitable difunctional components may include, but are not limited to, diethylene glycol diacrylate (eg, SR230 from Sartomer), triethylene glycol diacrylate (eg, SR272 from Sartomer), tetraethylene glycol Glycol Diacrylates (eg SR268 from Sartomer), Polyethylene Glycol Diacrylates (eg SR295, SR344 or SR610 from Sartomer), Polyethylene Glycol Dimethacrylates (eg SR603 from Sartomer) , SR644, SR252, or SR740), ethoxylated bisphenol A diacrylate (such as CD9038, SR349, SR601, or SR602 from Sartomer), ethoxylated bisphenol A dimethacrylate (such as CD540 from Sartomer) , CD542, SR101, SR150, SR348, SR480, or SR541), and urethane diacrylates (such as CN959, CN961, CN964, CN965, CN980, or CN981 from Sartomer; Ebecryl 230 from Cytec, Ebecryl 270, Ebecryl 8402, Ebecryl 8804, Ebecryl 8807, or Ebecryl 8808). Suitable photoinitiators may include, but are not limited to, iodophosphine oxide, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone , 2,4,6-trimethylbenzyldiphenylphosphine oxide, 2-isopropyl-9H-sulfur

-9-ketone (2-isopropyl-9H-thioxanthen-9-one), 4-benzyl-4'-methyldiphenyl sulfide, and 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy- 2-Methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one , 2,2-dimethoxy-1,2-diphenylethan-1-one, or 2-methyl-1[4-(methylthio)phenyl]-2-morpholinoprop-1 -ketone. Suitable mold release agents may include, but are not limited to, organically modified polysiloxane copolymers such as polysiloxane acrylates (eg, Ebercryl 1360 or Ebercyl 350 from Cytec), polysiloxane polyethers (eg, from Momentive) Silwet 7200, Silwet 7210, Silwet 7220, Silwet 7230, Silwet 7500, Silwet 7600, or Silwet 7607). The composition may further optionally contain one or more of the following components: a co-initiator, a monofunctional UV curable component, a multifunctional UV curable component, or a stabilizer.

The materials used as the filler phase in the adhesive material can be the same as those listed previously for the compounds incorporated into the laminate adhesive compositions described above.

The electro-optic medium present in displays fabricated in accordance with various embodiments of the present invention may be of any of the types previously discussed. Thus, the electro-optic medium within the binder may comprise, for example, droplets of a dispersion of coloured, charged particles, which are encapsulated in microcapsules or microcells, as appropriate; those comprising rotating polychromatic or dichromatic particles encapsulated in a fluid of dispersion droplets; or electrochromic media. However, it is generally preferred that the electro-optic medium be an electrophoretic medium comprising a plurality of capsules, each capsule comprising a capsule wall and an inner phase, which contains charged particles in a fluid and can move through the fluid when an electric field is applied to the electrophoretic medium, the electrophoretic medium A polymeric binder is further contained within which the capsule is held.

The electrophoretic media and displays of the present invention can use the same compositions and fabrication techniques as the aforementioned E Ink and MIT patents and applications, except that they comprise the composite material of the present invention. The reader is referred to these patents and applications, particularly the aforementioned US Pat. No. 6,831,769, for details on preferred materials and methods of fabricating encapsulated electrophoretic displays.

While preferred embodiments of the present invention have been shown and described herein, it should be understood that such embodiments are provided by way of example only. Numerous changes, changes and substitutions can be made by those skilled in the art without departing from the spirit of the invention. It is therefore intended that the appended claims cover all such changes that come within the spirit and scope of the present invention.

12: Conductive particles 14: Lamination Adhesive 16: Harness 100: Front plate laminate 110: Light-transmitting substrate 120: light-transmitting electrode layer 130: Electro-optic layer 140: Microcapsules 150: Negatively charged white particles 160: Positively charged black particles 165: Hydrocarbon fluid 170: Polymeric Binder 180: Laminated adhesive layer 190: Release film 202: Web 204: Web 206: Feed tray 208: Coating mold 210: Radiation Curable Laminate Adhesives 212: Radiation Sources 214: Feed tray 216: Meeting Point 218: Roller 220: Laminated web 222: Coiler 300: Double-sided release sheet 302: Central layer of electro-optic material 304: Sac 306: Polymeric Binder 308: The first adhesive layer 310: The first release sheet 312: Second adhesive layer 314: The second release sheet 400: Percolation threshold

The drawings depict one or more implementations in accordance with the concepts of the present invention, by way of example only and not limitation. In the drawings, the same reference numbers refer to the same or similar elements.

1 is a schematic cross-sectional view of a laminate of panels before passing through the present invention;

2 is a schematic cross-sectional view through the double-sided release film of the present invention;

3A and 3B are schematic cross-sectional views through an adhesive layer in two successive stages of the method of the present invention;

Figure 4 is a schematic side view of an apparatus that can be used to carry out the method of the present invention;

Figure 5 is a plot of volume ratio versus conductivity for a polymer composite; and

FIG. 6 is a plot of line y1 and line y2 of FIG. 5 .

100: Front plate laminate

110: Light-transmitting substrate

120: light-transmitting electrode layer

130: Electro-optic layer

140: Microcapsules

150: Negatively charged white particles

160: Positively charged black particles

170: Polymeric Binder

180: Laminated adhesive layer

190: Release film

Claims (18)

An electro-optic display comprising: a layer of electro-optic material, at least one conductor, and an adhesive material located between the layer of electro-optic material and the at least one conductor, wherein at least one of the electro-optic material and the adhesive material comprises a composite material , the composite material comprises a polymer phase and a filler phase, wherein the conductivity of the filler phase is greater than or equal to 0.5 × 10 ³ S/m, and the ratio of the thermal expansion coefficient of the filler to the polymer phase is less than or equal to 0.5, and the The concentration of the filler phase in the composite material is greater than or equal to the concentration of the filler phase corresponding to the conductivity transition point of the composite material. The electro-optic display of claim 1, wherein the composite material exhibits a rate of change in conductivity with temperature that is less than or equal to 60% of the change in conductivity with temperature of the polymer phase alone. The electro-optical display of claim 1, wherein the conductivity of the filler phase is greater than or equal to 10 X 10 ⁶ S/m. The electro-optical display of claim 1, wherein the conductivity of the filler phase is greater than or equal to 20 X 10 ⁶ S/m. The electro-optical display of claim 1, wherein the ratio of the thermal expansion coefficient of the filler to the polymer phase is less than or equal to 0.3. The electro-optic display of claim 1, wherein the ratio of the thermal expansion coefficient of the filler to the polymer phase is less than or equal to 0.1. The electro-optic display of claim 1, wherein the electro-optic material comprises a binder containing droplets of the dispersion. The electro-optic display of claim 7, wherein the droplets are encapsulated in microcapsules. The electro-optic display of claim 7, wherein the binder comprises a polymer phase and a filler phase. The electro-optical display of claim 7, wherein the dispersion comprises charged particles dispersed in a solvent. The electro-optic display of claim 10, wherein the charged particles include a plurality of colored particles. The electro-optic display of claim 1, wherein the electro-optic material comprises a binder, and the binder comprises a plurality of multi-colored particles encapsulated in the dispersion fluid. The electro-optical display of claim 12, wherein the binder comprises the polymer phase and the filler phase. The electro-optical display of claim 12, wherein the multicolor particles are bicolor. The electro-optic display of claim 1, wherein the electro-optic material comprises a polymeric film having a plurality of micelles. The electro-optic display of claim 15, wherein the polymeric film comprises the polymer phase and the filler phase. The electro-optic display of claim 15, wherein the micelles comprise a dispersion of charged particles dispersed in a solvent. The electro-optic display of claim 17, wherein the charged particles comprise a plurality of colored particles.

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