HK1060403A - Novel methods and compositions for improved electrophoretic display performance - Google Patents

Description

Method and composition for improving performance of electrophoretic displays

Technical Field

The present invention relates to novel methods and compositions for improving the performance of electrophoretic displays.

Background

Electrophoretic displays (EPDs) are non-emissive devices made based on the electrophoresis of charged pigment particles suspended in a solvent. This type of display was first proposed in 1969. Such displays usually comprise two plates with electrodes, which are placed opposite each other and separated by spacers. Typically, one of the electrode plates is transparent. An electrophoretic fluid comprising a colored solvent and charged pigment particles dispersed therein is sealed between the two electrode plates. When a voltage difference is applied between the two electrodes, the pigment particles will migrate to one side or the other, which makes the color of the pigment particles or the color of the solvent visible from the viewing side.

There are several different types of electrophoretic displays. In a segmented electrophoretic display (see m.a. hopper and v.novotny, institute of electrical and electronics engineers, volume 26, No.8, pp.1148-1152(1979)), a space is divided between two electrodes to divide the space into smaller cells to avoid unwanted migration of particles such as precipitates. Microcapsule-type electrophoretic displays (as described in U.S. patent nos. 5,961,804 and 5,930, 026) have a substantially two-dimensional arrangement of microcapsules, each containing an electrophoretic composition consisting of a dielectric fluid and a suspension of charged pigment particles (visually contrasting with the dielectric solvent). Another type of electrophoretic display (see U.S. patent No. 3,612,758) has electrophoretic cells formed from parallel line channels (line resonators). These trough-like electrophoresis cells are covered by and in electrical contact with a transparent conductor. A layer of transparent glass overlies the transparent conductor from the display panel viewing side.

An improved electrophoretic display manufacturing technique is disclosed in co-pending patent applications, U.S. application 09/518,488 (corresponding to WO01/67170) filed 3/2000, U.S. application 09/759,212 filed 11/2001, U.S. application 09/606,654 (corresponding to WO 02/01281) filed 6/28/2000, and U.S. application 09/784,972 filed 15/2/2001, all of which are incorporated herein by reference. The improved electrophoretic display cell may be prepared by micromolding a layer of a thermoplastic or thermosetting resin composition applied to a substrate layer to form microcups of well-defined shape, size, and aspect ratio. The microcups are then filled with electrophoretic fluid and sealed with a sealing layer. A second substrate layer is then laminated to the filled and sealed microcups, preferably with an adhesive layer.

To reduce irreversible electrodeposition of the dispersion particles or other charged species on the electrode (e.g., ITO), the electrode may be coated with a thin protective or barrier layer. In displays made by the microcup technology, the sealing layer and adhesive layer (if present) are actually protective layers on one electrode, while the microcup material (i.e., a thermoplastic or thermosetting resin composition) is a protective layer on the other electrode. These protective layers improve the performance of the display, including increasing the image uniformity and durability of the display. In addition, a faster electro-optic response is observed in displays with protective layers.

However, the thin protective layer approach also has disadvantages, such as the use of protective or isolating layers on the electrodes, which can lead to reduced contrast and bistability of the electrophoretic display. In displays with coated electrodes, higher Dmin (or lower whiteness or reflectance percentage) in the background is also generally observed, especially at low drive voltages.

Therefore, there is a need for more efficient methods to improve response rates and image uniformity and to reduce irreversible electrodeposition of dispersion particles or other charged species on the electrode.

Brief description of the invention

The present invention relates to novel methods and compositions for improving the performance of electrophoretic displays.

A first aspect of the invention relates to a method for improving the performance of an electrophoretic display, which method comprises adding a high absorbance dye or pigment to at least one electrode protecting layer of the display.

A second aspect of the invention relates to a method for improving the performance of an electrophoretic display, which method comprises incorporating conductive particles into at least one electrode protection layer of the display.

A third aspect of the invention relates to a method for improving the performance of an electrophoretic display, which method comprises incorporating charge transport material into at least one electrode protection layer of the display.

A fourth aspect of the invention relates to an adhesive composition comprising an adhesive material and a high absorbance dye or pigment, or conductive particles, or a charge transport material.

A fifth aspect of the invention relates to a sealing composition comprising a polymeric material and a high absorbance dye or pigment, or conductive particles, or a charge transport material.

A sixth aspect of the invention relates to a primer layer composition comprising a thermoplastic, thermoset, or precursor thereof and a high absorbance dye or pigment, or conductive particles, or a charge transport material.

The adhesive, sealant, and primer compositions of the present invention are particularly useful for electrophoretic displays prepared by microcup technology.

A seventh aspect of the invention relates to the use of a high absorbance dye or pigment, or conductive particles, or a charge transport material, or a combination thereof, to improve the performance of an electrophoretic display.

An eighth aspect of the present invention is directed to an electrophoretic display comprising at least one electrode protecting layer formed from a composition comprising a high absorbance dye or pigment, or conductive particles, or a charge transport material, or a combination thereof.

The electrophoretic display of the present invention exhibits increased contrast and image bistability (even at low drive voltages) without sacrificing display durability and image uniformity.

Brief description of the drawings

FIGS. 1A and 1B are schematic illustrations of an electrophoretic display cell prepared using microcup technology.

Detailed description of the invention definitions

Unless defined otherwise herein, technical terms used herein are used according to the customary definitions commonly used and understood by those skilled in the art.

The term "microcups" refers to cup-like recesses created by micro-molding or photolithography.

When referring to a microcup or cassette, the term "well-defined" means that the microcup or cassette has a well-defined shape, size, and aspect ratio that are predetermined according to the particular parameters of the present manufacturing process.

The term "aspect ratio" is a term commonly known in the art of electrophoretic displays. In this application, it refers to the depth to width, or depth to length, ratio of the microcups.

The term "maximum density (Dmax)" refers to the maximum optical density achievable by the display.

The term "minimum density (Dmin)" refers to the minimum optical density of the display background.

The term "contrast" refers to the ratio of the reflectance (percentage of reflected light) of the minimum density state to the reflectance of the maximum density state.

The term "charge transport material" is defined as a material that is capable of transporting electrons or holes from one side of the protective layer (e.g., the electrode side) to the other side (e.g., the electrophoretic fluid side), or vice versa. Electrons and holes are injected from the cathode and anode into the electron transporting and hole transporting layers, respectively. A summary of charge transport Materials can be found in the literature references, such as "photoreceptors" by p.m. bosenberger and d.s. weiss in Handbook of Imaging Materials (Handbook of Imaging Materials, pp.379 (1991), Marcel Dekker, inc.): organic compoundsPhotoconductors "(Phototeceptors: organic Photoconductors); sher and EW Montroll, Phys. Rev.,B122455 (1975); s.a. van Slyke et al, appl.phys.lett,692160 (1996); or f.nuesch et al, j.appl.phys.,87，7973(2000)。

the term "electrode protection layer" is defined in the following section. General description of the microcup technology

Figures 1A and 1B illustrate a typical display cell made with microcup technology, as disclosed in WO 01/67170. The microcup-based display cell 10 is sandwiched between a first electrode layer 11 and a second electrode layer 12. As can be seen in the figure, optionally a thin protective layer 13 is present between the cell 10 and the second electrode layer 12. As shown in fig. 1A, the thin protective layer 13 may be a primer layer (adhesion promoting layer) to improve the adhesion between the microcup material and the second electrode layer 12. On the other hand, if the array of microcups is prepared using a molding process, the thin protective layer 13 may be a thin layer of microcup material (as shown in FIG. 1B). The cartridge 10 is filled with electrophoretic fluid and sealed with a sealing layer 14 at the open side of the microcups. The first electrode layer 11 is laminated to the sealed cell, preferably with an adhesive 15.

In the context of the present specification, the term "electrode protection layer" may refer to a primer layer or thin microcup layer 13, a sealing layer 14, or an adhesive layer 15, as shown in fig. 1A and 1B.

In the case of an in-plane switching electrophoretic display, one of the electrode layers (11 or 12) may be replaced by an insulating layer.

The display panel may be produced by micro-embossing or photolithography, as disclosed in WO 01/67170. In the micro-molding method, a moldable composition is applied to the conductive side of the second electrode layer 12 and pressure molded to produce an array of microcups. To improve release properties, the conductive layer may be pretreated with a thin primer layer 13 prior to application of the moldable component.

The moldable component may comprise thermoplastic or thermoset materials, or precursors thereof, such as multifunctional vinyl compounds (including without limitation acrylates, methacrylates, allyl compounds, styrenes, vinyl ethers), multifunctional epoxides, and oligomers or polymers thereof, and the like. Multifunctional acrylates and their oligomers are most preferred. The combination of a multifunctional epoxide and a multifunctional acrylate is also very advantageous for obtaining the desired physico-mechanical properties. Typically, a low Tg binder or crosslinkable oligomer that imparts flexibility, such as urethane acrylate or polyester acrylate, is also added to improve the flex resistance of the molded microcups. The components may include oligomers, monomers, additives, and optionally polymers. The moldable component typically has a glass transition temperature (Tg) in the range of about-70 ℃ to about 150 ℃, preferably about-20 ℃ to about 50 ℃.

The micromolding process is typically carried out above the glass transition temperature. A heated male mold or heated die (housing) may be used, which is pressurized by a mold, to control the temperature and pressure of the micro-molding.

The mold is released during or after the hardening of the precursor layer to reveal the array of microcups 10. The precursor layer can be hardened with cooling, solvent evaporation, radiation crosslinking, heat, or moisture. If the thermosetting precursor is cured by irradiation with ultraviolet light, the ultraviolet light can be irradiated onto the thermosetting precursor through the transparent conductive layer. In addition, the UV lamp may be placed inside the mold. In this case, the mold must be transparent to allow ultraviolet light to be radiated onto the thermosetting precursor layer through the pre-patterned male mold.

After curing, the components of the primer layer are at least partially compatible with the mold component or the microcup material. In practice, the primer layer may be the same composition as the stamp component.

In general, the size of an individual microcup may range from about 10²To about 1X 10⁶μm²Preferably from about 10³To about 1X 10⁵μm². The depth of the microcups ranges from about 3 to about 100 microns, preferably from about 10 to about 50 microns. Ratio between open area and total areaAnd ranges from about 0.05 to about 0.95, preferably from about 0.4 to about 0.9. The distance of the openings (from edge to edge of the openings) is generally in the range of about 15 to about 450 microns, preferably from about 25 to about 300 microns.

The microcups are then filled and sealed with electrophoretic fluid as disclosed in co-pending patent applications, namely, U.S. application 09/518,488 filed 3/2000 (corresponding to WO01/67170), U.S. application 09/759,212 filed 11/1/2001, U.S. application 09/606,654 filed 28/6/2000 (corresponding to WO 02/01281), and U.S. application 09/784,972 filed 15/2/2001, all of which are incorporated herein by reference.

The microcups may be sealed by a variety of methods. Preferably, sealing is accomplished by coating the filled microcups with a sealing composition comprising a solvent and a sealing material selected from the group consisting of thermoplastic elastomers, multivalent acrylates or methacrylates, cyanoacrylates, multivalent vinyl compounds (including styrenes, vinylsilanes, vinyl ethers), multivalent epoxides, multivalent isocyanates, multivalent allylic compounds, oligomers or polymers containing crosslinkable functional groups, and the like. Additives such as polymeric binders or polymeric thickeners, photoinitiators, catalysts, vulcanizing agents, fillers, colorants, or surfactants may also be added to the seal composition to improve the physical mechanical and optical properties of the display. The encapsulating component is incompatible with the electrophoretic fluid and has a lower specific gravity than the electrophoretic fluid. After the solvent evaporates, the seal composition forms a consistent seamless seal at the top of the filled microcups. The sealing layer may be further hardened by heat, radiation, or other curing methods. Particularly preferred is sealing with a composition comprising a thermoplastic elastomer. Examples of thermoplastic elastomers include triblock or diblock copolymers of styrene and isoprene, butadiene or ethylene/butylene, such as Kraton from Kraton Polymer^TMSeries D and G. Crystalline rubbers, such as poly (ethylene-co-propylene-co-5-methylene-2-norbornene) and other EPDM (ethylene-propylene) s available from Exxon MobilDiene rubber terpolymers) are also very useful.

In addition, the sealing component can be dispersed into the electrophoretic fluid and fill the microcups. The encapsulating component is incompatible with and lighter than the electrophoretic fluid. After phase separation, the seal component floats to the top of the filled microcups and forms a seamless seal layer thereon after the solvent evaporates. The sealing layer may be further hardened by heat, radiation, or other curing methods.

Finally, the sealed microcups are laminated with a first electrode layer 11, which first electrode layer 11 may be pre-coated with an adhesive layer 15.

Preferred materials for the adhesive layer may be made of one adhesive or a mixture thereof selected from the group consisting of pressure sensitive adhesives, hot melt adhesives, and radiation curable adhesives. These binder materials may include: polyacrylates (acrylics), styrene-butadiene copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, polyvinyl butyral, cellulose acetate butyrate, polyvinyl pyrrolidone, polyurethanes, polyamides, ethylene-vinyl acetate copolymers, epoxies, multifunctional acrylates, vinyl compounds, vinyl ethers, and oligomers, polymers, and copolymers thereof. Additives comprising polymers or oligomers having a high acid or base content are particularly useful, such as polymers or copolymers derived from acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, vinyl pyridine, and derivatives thereof. The adhesive layer can be post-cured, e.g., by heat or radiation, e.g., by ultraviolet radiation after lamination.

Detailed description of the invention

As described above, the term "electrode protection layer" may refer to the primer layer 13, the sealing layer 14, or the adhesive layer 15, as shown in fig. 1A and 1B.

As noted above, the make layer 13 of the display may be formed from a composition that includes a thermoplastic or thermoset material, or a precursor thereof, such as a multifunctional acrylate or methacrylate, styrene, vinyl ether, epoxy, or oligomers or polymers thereof. Multifunctional acrylates and oligomers thereof are generally preferred. The primer layer has a thickness in the range of 0.1 to 5 micrometers, preferably 0.1 to 1 micrometer.

Sealing layer 14 is formed from a composition including a solvent and a material selected from the group consisting of thermoplastic elastomers, multivalent acrylates or methacrylates, cyanoacrylates, multivalent vinyl compounds (including styrene, vinyl silanes, vinyl ethers), multivalent epoxides, multivalent isocyanates, multivalent allyl compounds, oligomers or polymers containing crosslinkable functional groups, and the like. The thickness of the sealing layer ranges from 0.5 to 15 microns, preferably from 1 to 8 microns.

Suitable materials for the adhesive layer 15 may include: polyacrylates, styrene-butadiene copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, polyvinyl butyral, cellulose acetate butyrate, polyvinyl pyrrolidone, polyurethanes, polyamides, ethylene-vinyl acetate copolymers, epoxides, multifunctional acrylates, vinyl compounds, vinyl ethers, and oligomers, polymers, and copolymers thereof. The thickness of the adhesive layer ranges from 0.2 to 15 microns, preferably from 1 to 8 microns.

A first aspect of the present invention relates to a method for improving the performance of an electrophoretic display, which method comprises adding a high absorbance dye or pigment to at least one electrode protecting layer of the display. The dye or pigment may be dissolved or dispersed in the electrode protective layer.

The dye or pigment may be present in more than one electrode protection layer on the non-viewing side of the display device. If a dye or pigment is used in the primer layer or the microcup layer, the dye or pigment should not interfere with hardening or demolding in the micromolding process.

In addition to improving the commutation performance, the use of high absorbance dyes or pigments in the layer opposite the viewing side of the display also provides a dark background (dark background color) and enhanced contrast.

The dye or pigment preferably has an absorption band in the range of 320 to 800nm, more preferably 400 to 700 nm. Suitable dyes or pigments for use In the present invention include metal or naphthalocyanines (where the metal can be Cu, Al, Ti, Fe, Zn, Co, Cd, Mg, Sn, Ni, In, V, or Pb), metalloporphines (where the metal can be Co, Ni, or V), azo (e.g., diazo or polyazo) dyes, squaraine dyes, perylene dyes, and croconine dyes. Other dyes or pigments that generate or transport charge in an excited or ground state are also suitable. Examples of dyes or pigments of this type are those dyes or pigments which are conventionally used as charge generating materials in Organic Photoconductors (see "Photoreceptors: Organic Photoconductors" by P.M. Bosenberger and D.S. Weiss, Handbook of imaging materials, pp.379 (1991), Marcel Dekker, Ltd.) by A.S. Diamond. Particularly preferred dyes or pigments are: copper and naphthalocyanines, e.g. Orasol^TMBlue GN (color index, solvent blue 67), copper {29H, 31H-phthalocynaninato (2-) -N29, N30, N31, N32} - { {3- (1-methylethoxy) propyl } amino } sulfonyl derivative from Ciba Specialty chemicals (High Point, N.C.); a nickel phthalocyanine; a titanium phthalocyanine; nickel tetraphenylporphin; cobalt phthalocyanine; metalloporphin complexes, such as tetraphenylporphyrin vanadium (IV) oxide complexes and their alkylated or alkoxylated derivatives; orasol Black RLI (color index, solvent Black 29, 1: 2 chromium Complex from Ciba specialty Chemicals, Inc.); diazo or polyazo dyes, including Sudan dyes such as Sudan black B, Sudan blue, Sudan red, Sudan yellow, or Sudan I-IV; squaraine and croconine dyes, e.g. 1- (4-dimethylamino-phenyl) -3- (4-dimethylliminium-cyclohexyl (cyclohexoxa) -2, 5-dien-1-ylidene) -2-oxo-cyclobuten-4-ol ester (late), 1- (4-methyl-2-morpholinyl (morpholino) -selenazolyl (selenazo) -5-yl) -3- (2, 5-dihydro-4-methyl-2 [ morpholin-yl)-1-ylidene-onium]-selenazole-5-ylidene) -2-oxo-cyclobuten-4-ol ester, or 1- (2-dimethylamino-4-phenyl-thiazol-5-yl) -3- (2, 5-dihydro-2-dimethyllimtonium-4-phenyl) -thiazol-5-ylidene) -2-oxo-cyclobuten-4-ol ester; and condensed perylene dyes or pigments such as 2, 9-bis (2-hydroxyethyl) -anthracene [2, 1, 9-def: 6, 5, 10-d ' e ' f ']Bisisoquinoline-1, 3, 8, 10-tetraone, 9-bis (2-methoxyethyl) -anthracene [2, 1, 9-def: 6, 5, 10-d ' e ' f ']Bisisoquinoline-1, 3, 8, 10-tetrone, bisimidazo [2, 1-a: 2 ', 1 ' -a ']Anthracene [2, 1, 9-def: 6, 5, 10-d ' e ' f ']A di-isoquinoline-dione, or anthracene [2 ", 1", 9 ": 4,5,6: 6 ", 5", 10 ": 4',5',6']-bis-isoquinoline [2, 1-a: 2 ', 1' -a]Diperimidine-8, 20-dione.

Certain dyes or pigments such as metal (particularly Cu and Ti) phthalocyanines and naphthalocyanines may also be used as charge transport materials.

The concentration of the dye or pigment (by weight based on the total solids content of the layer) may range from about 01% to about 30%, preferably from about 2% to about 20%. Other additives such as surfactants, dispersing aids, thickeners, crosslinkers, vulcanizing agents, nucleating agents, or fillers may also be added to improve coating quality and display performance.

A second aspect of the invention relates to a method for improving the performance of an electrophoretic display, which method comprises incorporating particles of a conductive material into at least one electrode protection layer.

The conductive material includes, but is not limited to, an organic conductive compound or polymer, carbon black, carbonaceous material, graphite, metal alloy, or conductive metal oxide. Suitable metals include Au, Ag, Cu, Fe, Ni, In, Al, and alloys thereof. Suitable metal oxides include Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), Antimony Tin Oxide (ATO), barium titanate (BaTiO)₃) And the like. Suitable organic conductive compounds or polymers include poly (p-phenylene vinylene), polyfluorene, poly (4, 3-ethylenedioxythiophene), poly (1, 2-di-ethylthio-acetylene), poly (p-phenylene vinylene), poly (phenylene vinylene) (pex), poly1, 2-di-benzylthio-acetylene), 5, 6, 5 ', 6 ' -tetrahydro- [2, 2 ']Bis [1, 3]]Dithiol [4, 5-b ]][1，4]Dithienyl subunit (dithiinylidine)]4, 5, 6, 7, 4 ', 5 ', 6 ', 7 ' -octahydro- [2, 2 ']Bis [ benzo ]][1，3]Dithiolene, 4 '-diphenyl- [2, 2']Bis [1, 3]]Dithiolene, 2, 2, 2 ', 2 ' -tetraphenyl-di-thiopyran-4, 4 ' -diyl, hexabenzylthiobenzene, and derivatives thereof.

Organic and inorganic particles coated with any of the above-described conductive materials are also useful in the context of the present invention.

The addition of the conductive material in particulate form to the electrode protection layer improves contrast at low operating voltages. However, the amount of the conductive material added should be well controlled so that the conductive material does not cause short circuits or leakage current. The amount of conductive material added (by weight based on the total solids content of the layer) is preferably in the range of about 0.1% to about 40%, more preferably about 5% to about 30%.

Additives such as dispersants, surfactants, thickeners, crosslinkers, vulcanizing agents, or fillers may also be added to improve coating quality and display properties. More than one electrode protection layer may be added to the conductive material. The particle size of the conductive material is in the range of about 0.01 to about 5 μ n, preferably about 0.05 to about 2 μm.

A third aspect of the invention relates to a method for improving the performance of an electrophoretic display, which method comprises incorporating charge transport material into at least one electrode protection layer of the display.

Charge transport materials are materials that are capable of transporting electrons or holes from one side of the electrode protective layer (e.g., the electrode side) to the other side (e.g., the electrophoretic fluid side), or vice versa. Electrons and holes are injected from the cathode and anode into the electron transporting and hole transporting layers, respectively. Introduction of charge transport Materials can be found in the literature references, e.g., in A.S. Diamond, Handbook of development Materials (Handbook of Imaging Materials, pp.379 (1991), Marcel Dekker, Inc.)"photoreceptors" in the book p.m.bosenberger and d.s.weiss: organic photoconductors (Photoresist: organic photoconductors); sher and EW Montroll, Phys. Rev.,B122455 (1975); s.a. van Slyke et al, appl.phys.lett,692160 (1996); or f.nuesch et al, j.appl.phys.,87，7973(2000)。

suitable electron and hole transport materials can be found in the technical summaries for organic photoconductors and organic light emitting diodes, as listed in the above documents.

Typically, hole transport materials are compounds with low ionization potentials that can be estimated from their solution oxidation potentials. In the context of the present invention, compounds having an oxidation potential of less than 1.4V, in particular less than 0.9V (compared to Standard Calomel Electrode (SCE)), can be used as charge transport materials. Suitable charge transport materials should also have acceptable chemical and electrochemical stability, reversible redox properties, and sufficient solubility in the protective layers of the electrodes. Too low an oxidation potential can lead to undesirable oxidation in air and shorter display lifetime. Compounds with oxidation potentials between 0.5 and 0.9V (compared to standard calomel electrodes) are particularly useful for the present invention.

Particularly useful hole transport materials in the context of the present invention include the following general classes of compounds: pyrazolines, such as 1-phenyl-3- (4' -dialkylaminostyryl) -5- (4 "-dialkylaminophenyl) pyrazoline; hydrazones, such as p-dialkylaminobenzaldehyde-N, N-diphenylhydrazone, 9-ethyl-carbazole-3-acetaldehyde-N-methyl-N-phenylhydrazone, pyrene-3-acetaldehyde-N, N-diphenylhydrazone, 4-diphenylamino-benzaldehyde-N, N-diphenylhydrazone, 4-N, N-bis (4-tolyl) -amino-benzaldehyde-N, N-diphenylhydrazone, 4-dibenzylamino-benzaldehyde-N, N-diphenylhydrazone, or 4-dibenzylamino-2-methyl-benzaldehyde-N, N-diphenylhydrazone; oxazoles and oxadiazoles (oxadiazines), such as 2, 5-bis- (4-dialkylaminophenyl) -4- (2-chlorophenyl) oxazole, 2, 5-bis- (4-N, N '-dialkylaminophenyl) -1, 3, 4-oxadiazole, 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1, 2, 3-oxadiazole, 2' - (1, 3-phenylene) bis [5- [4- (1, 1-dimethylethyl) phenyl ]1, 3, 4-oxadiazole, 2, 5-bis (4-tolyl) -1, 3, 4-oxadiazole, or 1, 3-bis (4- (4-diphenylamino) -phenyl-1, 3, 4-oxadiazol-2-yl) benzene; enamines, carbazoles, or arylamines, in particular triarylamines, such as di (p-ethoxyphenyl) acetaldehyde di-p-methoxybenzylamine enamine, N-alkylcarbazole, trans-1, 2-dicarbazolyl-cyclobutane, 4 ' -di (carbazol-9-yl) -biphenyl, N ' -diphenyl-N, N ' -di (3-tolyl) - [1, 1-di [ phenyl ] -4, 4 ' -diamine, 4 ' -di (N-naphthyl-N-phenyl-amino) biphenyl (or N, N ' -di (naphthalen-2-yl) -N, N ' -diphenyl-benzidine); 4, 4 ', 4 "-trimethyl-triphenylamine, N-biphenyl-N-phenyl-N- (3-tolyl) amine, 4- (2, 2-diphenyl-ethen-1-yl) triphenylamine, N, N ' -bis- (4-methyl-phenyl) N, N ' -diphenyl-1, 4-phenylenediamine, 4- (2, 2-diphenyl-ethen-1-yl) -4 ', 4" -dimethyl-triphenylamine, N, N, N ', N ' -tetraphenylbenzidine, N, N, N ', N ' -tetrakis (4-tolyl) -benzidine, N, N ' -bis- (4-tolyl) -N, N ' -bis- (phenyl) -benzidine, N, N ' -diphenyl-1-yl-triphenylamine, N, N ' -bis- (4-tolyl) -benzidine, N, N ' -bis- (phenyl) -benzidine, N, N, 4, 4' -bis (diphenyl-azepin) -1-yl) biphenyl; 4, 4 '-bis (dihydro-diphenyl-azepin-1-yl) -biphenyl, bis- (4-dibenzylamino-phenyl) -ether, 1-bis- (4-bis (4-methyl-phenyl) -amino-phenyl) cyclohexane, 4' -bis (N, N-diphenylamino) -quaterphenyl, N, N, N ', N' -tetrakis (naphtha-2-yl) benzidine, N, N '-bis (phenanthren-9-yl) -N, N' -bis-phenyl-benzidine, 4 '-tris (carbazol-9-yl) -triphenylamine, bis (4-dibenzylamino-phenyl) -ether, bis (naphthaline-2-yl) benzidine, N, N, N', N '-tetrakis (phenanthren-9-yl) -N, N' -bis-phenyl-, 4, 4 ', 4 "-tris (N, N-diphenylamino) -triphenylamine, 4' -bis (N- (1-naphthyl) -N-phenyl-amino) -quaterphenyl, 4 ', 4" -tris (N- (1-naphthyl) -N-phenyl-amino) triphenylamine, or N, N' -diphenyl-N, N '-bis (4' - (N, N-bis (naphthalen-1-yl) -amino) -biphenyl-4-yl) -benzidine; triarylmethanes such as bis (4-N, N-dialkylamino-2-tolyl) -toluene; biphenyls, such as 4, 4' -bis (2, 2-diphenyl-ethen-1-yl) -biphenyl; dienes and dienones, such as 1, 1, 4, 4-tetraphenyl-butadiene, 4, 4' - (1, 2-dimethylene) -bis (2, 6-diphenyl-2, 5-cyclohexadiene-1-one), 2- (1, 1-dimethylethyl) -4- [3- (1, 1-dimethylethyl) -5-methyl-4-oxo-2, 5-cyclohexyl-dien-1-ylidene ] -6-methyl-2, 5-cyclohexadiene-1-one, 2, 6-bis (1, 1-dimethylethyl) 4- [3, 5-bis (1, 1-dimethylethyl) 4-oxo-2, 5-cyclohexyl-dien-1-ylidene ] -2, 5-cyclohexadiene-1-one, or 4, 4' - (1, 2-dimethylene) -bis (2, 6- (1, 1-dimethylethyl) 2, 5-cyclohexadiene-1-one); and triazoles, such as 3, 5-bis (4-tert-phenyl) -4-phenyl-triazole or 3- (4-biphenyl) -4-phenyl-5-tert-butylphenyl-1, 2, 4-triazole.

Oligomeric or polymeric derivatives containing any of the above functional groups may also be used as charge transport materials.

Particularly useful electron transport materials include the following general classes of electron deficient compounds: fluorenones, such as 2, 4, 7-trinitro-9-fluorenone, or 2- (1, 1-dimethylbutyl) -4, 5, 7-trinitro-9-fluorenone; and nitriles such as (4-butoxycarbonyl-9-fluorenylidene) malononitrile, 2, 6-di-tert-butyl-4-dicyanomethylmethane (dicyanomethylene) -4-H-thiopyran-1, 1-dioxide, 2- (4- (1-methyl-ethyl) -phenyl) -6-phenyl-4H-thiopyran-4-ylidene ] -malononitrile-1, 1-dioxide, or 2-phenyl-6-tolyl-4-dicyanomethane-4-H-thiopyran-1, 1-dioxide, or 7, 7, 8, 8-tetrachlorcyanoquinodimethane.

Oligomeric or polymeric derivatives containing any of the above functional groups are also useful.

The hole and electron transporting materials may coexist in the same layer or even the same molecule, or in different layers (opposite or the same side of the display cell). Dopants and host materials may also be added to the electrode protective layer, such as 4- (dicyanomethane) -2-methyl-6- (julolidin-4-yl-vinyl) -4H-pyran, bis (2-2-hydroxyphenyl) -phenyl-1, 3-thiazole ato) -Zn complex, bis (2- (2-hydroxyphenyl) -phenyl-1, 3-oxadiazole ato) -Zn complex, tris (8-hydroxy-quinoline ato) -Al complex, tris (8-hydroxy-4-methyl-quinoline ato) -Al complex, or tris (5-chloro-8-hydroxy-quinoline ato) -Al complex.

The charge transport material may be incorporated into the composition of one electrode protective layer, or may be present in more than one layer. Transparent and colorless charge transport materials are preferred if they are incorporated into the electrode protective layer on the viewing side of the display. The concentration of the charge transport material (based on the weight of the total solids content of the layer) may range from about 0.1% to about 30%, preferably from about 2% to about 20%. Other additives such as surfactants, dispersing aids, thickeners, crosslinkers, vulcanizing agents, nucleating agents, or fillers may also be added to improve coating quality and display performance.

It should be noted that these three aspects of the invention can be performed separately or in combination. One or more aspects of the present invention may also coexist in the same layer. The material used in the electrode protection layer on the viewing side of the display is preferably colorless and transparent. Furthermore, the materials used in the primer layer or microcup layer should not interfere with the hardening (e.g., uv light curing) or demolding of the layer in the molding process.

A fourth aspect of the invention relates to a binder composition comprising a binder material and a high absorbance dye or pigment, or conductive particles, or a charge transport material.

A fifth aspect of the invention relates to a sealing composition comprising a polymeric material and a high absorbance dye or pigment, or conductive particles, or a charge transport material.

A sixth aspect of the invention is directed to a primer layer composition comprising a thermoplastic, thermoset, or precursor thereof and a high absorbance dye or pigment, or conductive particles, or a charge transport material.

The sealing, adhesive, and primer compositions are particularly useful for electrophoretic displays prepared by microcup technology.

Suitable binder materials, sealants, primer materials, thermoplastic or thermoset materials, high absorbance dyes or pigments, conductive particles, and charge transport materials for use in these compositions are described herein.

A seventh aspect of the present invention is directed to the use of a high absorbance dye or pigment, conductive particles, a charge transport material, or a combination thereof, to improve the performance of an electrophoretic display.

An eighth aspect of the present invention is directed to an electrophoretic display comprising at least one electrode protecting layer formed from a composition comprising a high absorbance dye or pigment, or conductive particles, or a charge transport material, or a combination thereof.

While microcup technology is discussed extensively in this application (as disclosed in WO01/67170), it should be understood that the methods, compositions, and applications of the present invention are applicable to all types of electrophoretic displays, including, but not limited to, microcup-based displays (WO 01/67170), segmented displays (see m.a. hopper and v.novotny, institute of electrical and electronics engineers electric materials de-volume (IEEE trans. electric. dev.), volume ED26, No.8, pp.1148-1152(1979)), microcapsule-type displays (U.S. patent nos. 5,961,804 and 5,930,026), and micro-trough-type displays (U.S. patent No. 3,612,758).

Description of The Preferred Embodiment

The following examples are set forth to provide those skilled in the art with a clear understanding of the invention and are not to be construed as limiting the scope of the invention but merely as providing illustrations and exemplifications of the invention.Comparative example 1 Example 1A: preparation of transparent conductive film of undercoat layer

A primer solution containing 33.2 grams of EB 600 was thoroughly mixed and coated onto a 3 mil (mil) transparent conductive film (ITO/PET film, 5 mil OC50, CP Films from Martinsville, Va.) using a #4 wire rod^TM(UCB, Smyrna, Georgia), 16.12 g SR 399^TM(Sartomer, Exton, Pa.), 16.12 grams TMPTA (UCB, Smyrna, Georgia), 20.61 grams HDODA (UCB, Smyrna, Georgia), 2 grams Irgacure^TM369(Ciba, Tarrytown, N.Y.), 0.1 g Irganox^TM1035(Ciba, Inc.), 44.35 grams of polyethylmethacrylate (molecular weight 515,000, Aldrich, Milwaukee, Wis.), and 399.15 grams of butanone. The coated ITO film was dried in an oven at 65 ℃ for 10 minutes and then subjected to 1.8J/cm under nitrogen atmosphere using an ultraviolet ray transmitting apparatus (DDU, Los Angles of California)²Ultraviolet curing.Example 1B: preparation of the microcups

TABLE 1 Mini cup composition

Composition (I)	Parts by weight	Origin of origin
			EB600	33.15	UCB
SR399	32.24	Sartomer
			HDDA	20.61	UCB
EB1360	6.00	UCB
			Hycar X43	8.00	BF Goodrich
Irgacure 369	0.20	Ciba
			ITX	0.04	Aldrich
Antioxidant Ir1035	0.10	Ciba

33.15 g of EB 600^TM(UCB, Smyrna, Georgia), 32.24 g SR 399^TM(Sartomer, Exton, Pa.), 6.00 g EB1360^TM(UCB, Smyrna, Georgia), 8 grams of Hycar 1300X 43 (living liquid Polymer, Noveon, Cleveland, Ohio), 0.2 grams of Irgacure^TM369(Ciba, Tarrytown, N.Y.), 0.04 g of ITX (isopropyl-9H-thioxanthen-9-one, Aldrich, Milwaukee, Wis.), 0.1 g of Irganox^TM1035(Ciba, Tarrrytown, N.Y.), and 20.61 grams of HDDA (1, 6-hexanediol diacrylate, UCB, Smyrna, Ga.), were thoroughly mixed at room temperature for about 1 hour using a Stir-Pak mixer (Cole Parmer, Vernon, Ill.) and then degassed at 2000 rpm for about 15 minutes using a centrifuge.

Handle barThe cup-type composition was slowly applied to an electroformed 4 '. times.4' nickel punch used to obtain an array of microcups 72 μm in length by 72 μm in width by 35 μm in depth by 13 μm in width of the top surface of the space between the microcups. A plastic blade was used to remove excess fluid and gently squeeze the composition into the "valleys" of the nickel mold. The coated nickel mold was heated in an oven at 65 ℃ for 5 minutes and laminated using a GBC Eagle35 laminator (from GBC corporation, Northbrook, illinois) with the primer layer of the ITO/PET film (prepared in example 1A) with the primer layer facing the nickel mold and the laminator set up as follows: the roll temperature was 100 ℃, the lamination speed was 1 foot/min and the roll gap was "coarse gauge". The intensity of the ultraviolet ray used is 2.5mJ/cm²To cure the panel for 5 seconds. The ITO/PET film was then peeled from the nickel mold at an angle of approximately 30 degrees to produce a 4 "array of microcups on the ITO/PET film. Acceptable release of the microcup array was observed. The microcup array thus obtained was further post-cured with an ultraviolet conveyor curing system (DDU, Los Angles of California) having an ultraviolet intensity of 1.7J/cm²。Example 1C: preparation of electrophoretic fluids

Adding 5.9 g of TiO₂ R900^TM(DuPont Corp.) 3.77 g of butanone, 4.54 g of N3400^TMAliphatic polyisocyanate (Bayer AG) and 0.77 g of 1- [ N, N-bis (2-hydroxyethyl) amino]-2-propanol (Aldrich). The resulting slurry was homogenized at 5 to 10 ℃ for 1 minute, then 0.01 g of dibutyltin dilaurate (Aldrich) was added and the mixture was homogenized for an additional 1 minute. Finally adding a solution containing 20 g of HT-200^TM(Ausimont, Thorofur, N.J.) and 0.47 g of Rf-amine 4900[ Krytox methyl ester (from DuPont) and tris (2-aminoethyl) amine (Aldrich) prepared as follows [ ]]The mixture was again homogenized at room temperature for 3 minutes.

Rf-amine 4900 is prepared according to the following reaction:(Rf-amine 4900; n ═ about 30)

The slurry prepared above was slowly added to a mixture containing 31 g of HT-200 and 2.28 g of Rf-amine 4900 over a period of 5 minutes at room temperature with homogenization. The resulting TiO was stirred (under low shear) at 35 ℃ with a mechanical stirrer₂The microcapsule dispersion was held for 30 minutes and then heated to 85 ℃ to remove the butanone and post cure the internal phase for 3 hours. The dispersion exhibits a narrow particle size distribution: from 0.5 to 3.5 microns. With an equal amount of PFS-2^TM(Auismont, Thorofur, N.J.) diluted the slurry and the microcapsules were separated by centrifugal fractionation to remove the solvent phase. By PFS-2^TMThe collected solid was washed thoroughly and redispersed in HT-200.Example 1D: filling and sealing with a sealing composition

1 gram of an electrophoretic composition containing 6 parts (on a dry weight basis) of the TiO prepared above was dosed into a 4 '. times.4' microcup array prepared according to example 1B₂Microparticles and 94 parts of HT-200 (Ausimont) solution containing 1.5% (weight percent) perfluorinated copper phthalocyanine dye (FC-3275, from 3M company, St.Paul, Minn.). Excess fluid was scraped off with a rubber blade. A10% rubber solution comprising 9 parts Kraton G1650 (Shell, Tex.), 1 part GRP6919(Shell, Inc.), 3 parts Carb-O-Sil TS-720 (Cabot Corp. Inc. Illinois), 78.3 parts Isopar E, and 8.7 parts isopropyl acetate was then coated onto the filled microcups with a universal blade coater and dried at room temperature to form a seamless seal layer of good uniformity about 2 to 3 microns thick (dry).Example 1E: lamination of

A 25 weight percent solution of a pressure sensitive adhesive (Durotak 1105, National Starch, Bridgewater, nj) in Methyl Ethyl Ketone (MEK) was applied to the ITO side (target coverage area: 0.6 grams per square foot) of an ITO/PET conductive film (5 mil OC50, from CP Films) using a mylad rod. The adhesive coated ITO/PET layer was then laminated to the sealed microcups (according to GBCEagle35 laminator at 70 ℃Example 1D preparation). The lamination speed was set at 1 ft/min and the gap was 1/32 ". The display panel thus prepared had a contrast of 1.5 against a black background at ± 20V.Example 2

The procedure of example 1 was repeated except that the sealing layer (example 1D) and the adhesive layer (example 1E) were replaced with the sealing layer of example 2A and the adhesive layer of example 2B, respectively.Example 2A: sealing layer composition containing carbon black

27.8 g of carbon black (Vulcan) are placed on a high-speed disperser (Powergen, model 700, equipped with a 20mm sawtooth shaft)^TMXC72, Cabot corp. co.) was well dispersed in 320 g of isopropyl acetate/Isopar E (1/9) solution containing 0.75% (weight percent) of Disperse-Ayd6(Elementis Specialties co.). 10% by weight of a rubber solution (80 g) comprising 9 parts of Kraton was added to the carbon black dispersion and mixed for an additional 30 minutes^TMG1650, 9 parts of Kraton^TMRPG6919 (from Shell chemical company), 1 part isopropyl acetate, and 81 parts Isopar-E. The resulting carbon black dispersion was compounded with an additional 1780 grams of the same 10% rubber (Kraton)^TMG1650/Kraton^TMRPG6919 ═ 9/1) solution, homogenized for 2 hours using a silverson l4RT-a homogenizer, and filtered through a 40 μm filter.Example 2B: dye-containing adhesive layer composition

A mixture containing 6.0 grams of 25% (weight percent) Orasol^TMBlue GL (Ciba Specialty Chemicals, High Point, N.C.) in butanone, 20.0 grams Duro-Tak^TMA solution of 80-1105 adhesive (50% solids from National Starch, Bridgewater, nj) and 51.0 grams of butanone was coated onto the ITO side of the ITO/PET film and laminated to a sealed array of microcups containing electrophoretic fluid (as prepared in example 1). The target coverage area of the adhesive remains the same: 0.6 g/ft². The contrast of the display panel at ± 20V was 6.2.Examples 3 to 7

The procedure of example 2 was repeated exceptCharacterized in that different dyes are used instead of Orasol in the adhesive layer^TMBlue GL, as shown in Table 1.

TABLE 1 influence of dyes and carbon black in adhesive and sealing layers

	Additives in adhesive layers	Additives in sealing layers	Contrast ratio at + -20V	Contrast ratio at + -30V
					Comparative example 1	Is free of	Is free of	1.5	2.2
Example 2	13% by weight of Orasol blue GL	13% by weight of carbon black	6.2	9.3
					Example 3	13% (weight percent) Orasol Red BL	13% by weight of carbon black	6.0	8.5
Example 4	13% by weight of Orasol yellow 2GLN	13% by weight of carbon black	5.5	8.2
					Example 5	13% by weight of Orasol Black CN	13% by weight of carbon black	5.2	8.1
Example 6	13% by weight of Orasol Black RLI	13% by weight of carbon black	5.0	7.2
					Example 7	13% (by weight) of Sudan black	13% by weight of carbon black	5.0	6.7

All Orasol in Table 1^TMThe dye was from Ciba Specialty Chemicals, while Sudan Black was from Aldrich.Example 8

The procedure of example 2 was repeated except that barium titanate (BaTiO) was used₃) Replacement of Orasol in adhesive layer^TMBlue GL. Thus, 12 grams of barium titanate (K-Plus-16 from Cabot, Mass.) was dispersed in a dispersion containing 15.5 grams of Duro-Tak using a sonicator (Fisher De membranator, model 550)^TM80-1105, 18.8 grams ethyl acetate, 15.9 grams toluene, 1.4 grams hexane, and 1.1 grams of a polymeric dispersant (Disperbyk 163, BYK Chemie). The adhesive was applied to the ITO side of an ITO/PET film (target dry coverage: 6mm), and the resulting film was laminated at 100 deg.COn a sealed array of microcups (as in example 2).

The contrast of the display panel at ± 30V was 6.1.Comparative example 9

The procedure of example 8 was repeated except that no BaTiO was used in the adhesive layer₃(target dry coverage: 6 μm).

The contrast of the display panel at ± 30V was 4.7.Example 10

The procedure of example 2 was repeated except that N, N '- (di (3-tolyl) -N-N' -diphenylbenzidine) (BMD) was used in place of Orasol in the adhesive layer^TMBlue GL. Thus, 0.42 g BMD was dissolved in 28 g 10% (weight percent) of the binder Duro-Tak at 80 deg.C^TM80-1105 in Dimethylformamide (DMF). The resulting adhesive solution was coated onto the ITO side of a 5 mil ITO/PET film using a 12-wire rod and the resulting film was laminated to a sealed array of microcups at 100 ℃ (as in example 2).

The contrast of the display panel is about 3 at ± 20V.Comparative example 11

The procedure of example 10 was repeated except that no BMD was used in the adhesive layer. The contrast of the display panel thus manufactured was about 2 at ± 20V.

While the invention has been described with reference to specific embodiments thereof, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition, process step or steps, to the objective, spirit and scope of the present invention. All such modifications are intended to be within the scope of the appended claims.

Claims (70)

1. A method for improving the performance of an electrophoretic display, the method comprising adding a high absorbance dye or pigment to at least one electrode protecting layer of the display.

2. The method of claim 1, wherein the dye or pigment has an absorption band in the range of 320 to 800 nm.

3. The method of claim 2, wherein the dye or pigment has an absorption band in the range of 400 to 700 nm.

4. The method of claim 1, wherein the dye or pigment is selected from the group consisting of a metallophthalocyanine or naphthalocyanine dye, a metalloporphine dye, an azo dye, a squaraine dye, a perylene dye, and a croconine dye.

5. The method of claim 4, wherein the metal In the metal phthalocyanine or naphthalocyanine dye is Cu, Al, Ti, Fe, Zn, Co, Cd, Mg, Sn, Ni, In, V, or Pb.

6. The method of claim 4, wherein the metal in the metalloporphine dye is Co, Ni, or V.

7. The method of claim 4, wherein the azo dye is a diazo or polyazo dye.

8. The method of claim 1, wherein the dye or pigment is a charge generating material used in an organic photoconductor.

9. The method of claim 1, wherein the dye or pigment is selected from the group consisting of copper phthalocyanine, copper naphthalocyanine, oil-soluble blue 67, nickel phthalocyanine, titanium phthalocyanine, nickel tetraphenylporphin, cobalt phthalocyanine, Orasol^TMBlue GL, Orasol^TMRed BL, Orasol^TMYellow 2GLN, Orasol^TMBlack CN, Orasol^TMBlack RL1, tetraphenylporphyrin vanadium (IV) oxide complexes and their alkylated or alkoxylated derivatives, color index solvent Black 29, Sudan Black B, Sudan blue, Sudan Red, Sudan yellow, Sudan I, Sudan II, Sudan III, Sudan IV, 1- (4-dimethylamino-phenyl) -3- (4-dimethylliminium-cyclohexyl-2, 5-dien-1-ylidene) -2-oxo-cyclobuten-4-ol, 1- (4-methyl-2-morpholinyl-selenazol-5-yl) -3- (2, 5-dihydro-4-methyl-2 [ morpholin-1-ylidene-onium ] 2]-selenazol-5-ylidene) -2-oxo-cycloButene-4-phenol ester, 1- (2-dimethylamino-4-phenyl-thiazol-5-yl) -3- (2, 5-dihydro-2-dimethylliminium-4-phenyl) -thiazol-5-ylidene) -2-oxo-cyclobutene-4-phenol ester; 2, 9-bis (2-hydroxyethyl) -anthracene [2, 1, 9-def: 6, 5, 10-d ' e ' f ']Bisisoquinoline-1, 3, 8, 10-tetraone, 9-bis (2-methoxyethyl) -anthracene [2, 1, 9-def: 6, 5, 10-d 'e' f]Bisisoquinoline-1, 3, 8, 10-tetrone, bisimidazo [2, 1-a: 2 ', 1 ' -a ']Anthracene [2, 1, 9-def: 6, 5, 10-d ' e ' f ']Di-isoquinoline-diones, and anthracenes [2 ", 1", 9 ": 4,5,6: 6 ", 5", 10 ": 4',5',6']-bis-isoquinoline [2, 1-a: 2 ', 1' -a]A di-perimidine-8, 20-dione.

10. An electrode protection layer composition comprising a high absorbance dye or pigment.

11. The composition of claim 10, wherein the dye or pigment has an absorption band in the range of 320 to 800 nm.

12. The composition of claim 11, wherein the dye or pigment has an absorption band in the range of 400 to 700 nm.

13. The composition of claim 10, being a primer layer composition comprising a thermoplastic, thermoset, or precursor thereof and a high absorption dye or pigment.

14. The composition of claim 13, wherein the thermoplastic, thermoset is selected from the group consisting of polyvinyl butyral, cellulose acetate butyrate, polyalkylacrylates, polyalkylmethacrylates, polyethers, polyurethanes, polyamides, polyesters, polycarbonates, multifunctional acrylates or methacrylates, styrene, vinyl ethers, epoxides, and oligomers or polymers thereof.

15. The composition of claim 10, being a sealant layer composition comprising a polymeric material and a high absorbance dye or pigment.

16. The composition of claim 15, wherein the polymeric material is selected from the group consisting of thermoplastic elastomers, multivalent acrylates or methacrylates, cyanoacrylates, multivalent vinyl compounds (including styrene, vinyl silanes, vinyl ethers), multivalent epoxides, multivalent isocyanates, multivalent allyl compounds, and oligomers or polymers containing crosslinkable functional groups.

17. The composition of claim 10, being a binder layer composition comprising a binder material and a high absorbance dye or pigment.

18. The composition of claim 17, wherein the binder material is selected from the group consisting of acrylic resins, styrene-butadiene copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, polyvinyl butyral, cellulose acetate butyrate, polyvinyl pyrrolidone, polyurethanes, polyamides, ethylene-vinyl acetate copolymers, epoxides, multifunctional acrylates, vinyl compounds, vinyl ethers, and oligomers, polymers, and copolymers thereof.

19. The composition of claim 10, wherein the amount of the dye or pigment is 0.1 to 30% by weight based on the total solid content of the electrode protective layer.

20. The composition of claim 19, wherein the amount of the dye or pigment is 2 to 20% by weight based on the total solid content of the electrode protective layer.

21. A method of improving the performance of an electrophoretic display comprises incorporating conductive particles into an electrode protective layer of the display.

22. The method of claim 21, wherein the conductive particles are formed from a conductive material selected from the group consisting of organic conductive compounds or polymers, carbon black, carbonaceous materials, graphite, metals, metal alloys, and conductive metal oxides.

23. The method of claim 22, wherein the metal or metal alloy is selected from the group consisting of Au, Ag, Cu, Fe, Ni, In, Al, and alloys thereof.

24. The method of claim 22, wherein the metal oxide is selected from the group consisting of Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), Antimony Tin Oxide (ATO), and barium titanate (BaTiO)₃) Group (d) of (a).

25. The method of claim 22, wherein the organic conducting compound or polymer is selected from the group consisting of poly (p-phenylene vinylene), polyfluorene, poly (4, 3-ethylenedioxythiophene), poly (1, 2-di-ethylthio-acetylene), poly (1, 2-di-benzylthio-acetylene), 5, 6, 5 ', 6' -tetrahydro- [2, 2 '] bis [1, 3] dithiol [4, 5-b ] [1, 4] dithienylidene ], 4, 5, 6, 7, 4', 5 ', 6', 7 '-octahydro- [2, 2' ] bis [ benzo ] [1, 3] dithiolidene, 4 '-diphenyl- [2, 2' ] bis [1, 3] dithiolidene, 2, 2 ', 2' -tetraphenyl-bis-thiopyran-4, 4' -diylidene, hexabenzylthiobenzene, and derivatives thereof.

26. The method of claim 22, wherein said conductive particles are organic or inorganic particles coated with a conductive material.

27. The method of claim 22, wherein the amount of the conductive material added to the electrode protection layer is in the range of 0.1% to 40% based on the total solid weight of the electrode protection layer.

28. The method of claim 22, wherein the amount of the conductive material added to the electrode protection layer is in the range of 5% to 30% based on the total solids weight of the electrode protection layer.

29. The method of claim 22, wherein the conductive material is in the form of particles of 0.01 to 5 μ ι η.

30. The method of claim 29, wherein the conductive material is in the form of particles of 0.05 to 2 μ ι η.

31. An electrode protection layer composition includes conductive particles.

32. The composition of claim 31, wherein the conductive particles are formed from a conductive material selected from the group consisting of an organic conductive compound or polymer, carbon black, carbonaceous material, graphite, metal alloy, or conductive metal oxide, and organic or inorganic particles coated with a conductive material.

33. The composition of claim 32, being a primer layer composition comprising a thermoplastic, thermoset, or precursor thereof and conductive particles.

34. The composition of claim 33, wherein the thermoplastic or thermoset is selected from the group consisting of polyvinyl butyral, cellulose acetate butyrate, polyalkylacrylates, polyalkylmethacrylates, polyethers, polyurethanes, polyamides, polyesters, polycarbonates, multifunctional acrylates or methacrylates, styrene, vinyl ethers, epoxides, and oligomers or polymers thereof.

35. The composition of claim 32, being a sealant layer composition comprising a polymeric material and conductive particles.

36. The composition of claim 35, wherein the polymeric material is selected from the group consisting of thermoplastic elastomers, multivalent acrylates or methacrylates, cyanoacrylates, multivalent vinyl compounds including styrene, vinylsilanes, vinyl ethers, multivalent epoxides, multivalent isocyanates, multivalent allyl compounds, and oligomers or polymers containing crosslinkable functional groups.

37. The composition of claim 32, being an adhesive layer composition comprising an adhesive material and conductive particles.

38. The composition of claim 37, wherein the binder material is selected from the group consisting of polyacrylates, styrene-butadiene copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, polyvinyl butyral, cellulose acetate butyrate, polyvinyl pyrrolidone, polyurethanes, polyamides, ethylene-vinyl acetate copolymers, epoxides, multifunctional acrylates, vinyl compounds, vinyl ethers, and oligomers, polymers, and copolymers thereof.

39. The composition of claim 31, wherein the amount of the conductive particles is 0.1 to 40% by weight based on the total solid content of the electrode protective layer.

40. The composition of claim 39, wherein the conductive particles are in the range of 5 to 30% by weight based on the total solid content of the electrode protective layer.

41. A method of improving the performance of an electrophoretic display comprising incorporating a charge transport material into one of the electrode protective layers of the display.

42. The method of claim 41, wherein the charge transport material is a hole transport material having an oxidation potential of less than 1.4V (compared to a standard calomel electrode).

43. The method of claim 42, wherein the charge transport material is a hole transport material having an oxidation potential of less than 0.9V (compared to a standard calomel electrode).

44. The method of claim 43, wherein the oxidation potential of the hole transport material ranges from 0.5 to 0.9V (compared to a standard calomel electrode).

45. The method of claim 42, wherein the hole transport material is selected from the group consisting of pyrazolines, hydrazones, oxazoles, oxadiazoles, enamines, carbazoles, arylamines, triarylmethanes, biphenyls, dienes, dienones, triazoles, metal phthalocyanines, metal naphthalocyanines, and oligomeric or polymeric derivatives thereof.

46. The method according to claim 45, wherein said pyrazoline is 1-phenyl-3- (4' -dialkylaminostyryl) -5- (4 "-dialkylaminophenyl) pyrazoline.

47. The method of claim 45, wherein the hydrazone is p-dialkylaminobenzaldehyde-N, N-diphenylhydrazone, 9-ethyl-carbazole-3-acetaldehyde-N-methyl-N-phenylhydrazone, pyrene-3-acetaldehyde-N, N-diphenylhydrazone, 4-diphenylamino-benzaldehyde-N, N-diphenylhydrazone, 4-N, N-bis (4-tolyl) -amino-benzaldehyde-N, N-diphenylhydrazone, 4-dibenzylamino-benzaldehyde-N, N-diphenylhydrazone, or 4-dibenzylamino-2-methyl-benzaldehyde-N, N-diphenylhydrazone.

48. The method according to claim 45, wherein the oxazole or oxadiazole is 2, 5-bis- (4-dialkylaminophenyl) -4- (2-chlorophenyl) oxazole, 2, 5-bis- (4-N, N '-dialkylaminophenyl) -1, 3, 4-oxadiazole, 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1, 2, 3-f-oxadiazole, 2' - (1, 3-phenylene) bis [5- [4- (1, 1-dimethylethyl) phenyl ]1, 3, 4-oxadiazole, 2, 5-bis (4-tolyl) -1, 3, 4-oxadiazole, or 1, 3-bis (4- (4-diphenylamino) -phenyl-1, 3, 4-oxadiazol-2-yl) benzene.

49. The method of claim 45, wherein the enamine, carbazole, or arylamine is bis (p-ethoxyphenyl) acetaldehyde di-p-methoxybenzylamine enamine, N-alkylcarbazole, trans-1, 2-dicarbazolyl-cyclobutane, 4 ' -bis (carbazol-9-yl) -biphenyl, N ' -diphenyl-N, N ' -bis (3-tolyl) - [1, 1-bis [ phenyl ] -4, 4 ' -diamine, 4 ' -bis (N-naphthyl-N-phenyl-amino) biphenyl (or N, N ' -bis (naphthalen-2-yl) -N, N ' -diphenyl-benzidine); 4, 4 ', 4 "-trimethyl-triphenylamine, N-biphenyl-N-phenyl-N- (3-tolyl) amine, 4- (2, 2-diphenyl-ethen-1-yl) triphenylamine, N, N ' -bis- (4-methyl-phenyl) N, N ' -diphenyl-1, 4-phenylenediamine, 4- (2, 2-diphenyl-ethen-1-yl) -4 ', 4" -dimethyl-triphenylamine, N, N, N ', N ' -tetraphenylbenzidine, N, N, N ', N ' -tetrakis (4-tolyl) -benzidine, N, N ' -bis- (4-tolyl) -N, N ' -bis- (phenyl) -benzidine, N, N ' -diphenyl-1-yl-triphenylamine, N, N ' -bis- (4-tolyl) -benzidine, N, N ' -bis- (phenyl) -benzidine, N, N, 4, 4' -bis (diphenyl-azepin-1-yl) -biphenyl; 4, 4 '-bis (dihydro-diphenyl-azepin-1-yl) -biphenyl, bis- (4-dibenzylamino-phenyl) -ether, 1-bis- (4-bis (4-methyl-phenyl) -amino-phenyl) cyclohexane, 4' -bis (N, N-diphenylamino) -quaterphenyl, N, N, N ', N' -tetrakis (naphtha-2-yl) benzidine, N, N '-bis (phenanthren-9-yl) -N, N' -bis-phenyl-benzidine, 4 '-tris (carbazol-9-yl) -triphenylamine, bis (4-dibenzylamino-phenyl) -ether, bis (naphthaline-2-yl) benzidine, N, N, N', N '-tetrakis (phenanthren-9-yl) -N, N' -bis-phenyl-, 4, 4 ', 4 "-tris (N, N-diphenylamino) -triphenylamine, 4' -bis (N- (1-naphthyl) -N-phenyl-amino) -quaterphenyl, 4 ', 4" -tris (N- (1-naphthyl) -N-phenyl-amino) triphenylamine, or N, N' -diphenyl-N, N '-bis (4' - (N, N-bis (naphthyl-1-yl) -amino) -biphenyl-4-yl) -benzidine.

50. The process of claim 45, wherein the triarylmethane or biphenyl is bis (4-N, N-dialkylamino-2-tolyl) toluene or 4, 4' -bis (2, 2-diphenyl-ethen-1-yl) -biphenyl.

51. The process of claim 45, wherein the diene or dienone is 1, 1, 4, 4-tetraphenyl-butadiene, 4, 4' - (1, 2-dimethylene) -bis (2, 6-dimethyl-2, 5-cyclohexadiene-1-one), 2- (1, 1-dimethylethyl) -4- [3- (1, 1-dimethylethyl) -5-methyl-4-oxo-2, 5-cyclohexyl-dien-1-ylidene ] -6-methyl-2, 5-cyclohexadiene-1-one, 2, 6-bis (1, 1-dimethylethyl) 4- [3, 5-bis (1, 1-dimethylethyl) 4-oxo-2, 5-cyclohexyl-dien-1-ylidene ] -2, 5-cyclohexadiene-1-one, or 4, 4' - (1, 2-dimethylene) -bis (2, 6- (1, 1-dimethylethyl) 2, 5-cyclohexadiene-1-one).

52. The method of claim 45, wherein the triazole is 3, 5-bis (4-tert-phenyl) -4-phenyl-triazole, or 3- (4-biphenyl) -4-phenyl-5-tert-butylphenyl-1, 2, 4-triazole.

53. The method of claim 45, wherein the metal phthalocyanine or naphthalocyanine is copper phthalocyanine, copper naphthalocyanine, or alkylated derivatives thereof.

54. The method of claim 41, wherein said charge transport material is an electron transport material.

55. The method of claim 54, wherein said electron transport material is an electron deficient compound selected from the general class consisting of: fluorenone, nitro and nitrile compounds, and oligomeric or polymeric derivatives thereof.

56. The method of claim 55, wherein said electron transporting material is 2, 4, 7-trinitro-9-fluorenone, 2- (1, 1-dimethylbutyl) -4, 5, 7-trinitro-9-fluorenone, (4-butoxycarbonyl-9-fluorenylidene) malononitrile, 2, 6-di-tert-butyl-4-dicyanomethane-4-H-thiopyran-1, 1-dioxide, 2- (4- (1-methyl-ethyl) -phenyl) -6-phenyl-4H-thiopyran-4-ylidene ] -malononitrile-1, 1-dioxide, or 2-phenyl-6-tolyl-4-dicyanomethane-4-H-thiopyran-1, 1-dioxide, or 7, 7, 8, 8-tetrachlorocyanoquinodimethane.

57. An electrode protection layer composition includes a charge transport material.

58. The composition according to claim 57, wherein the charge transport material is a hole transport material or an electron transport material.

59. The composition of claim 57, wherein said charge transport material is 4- (dicyanomethane) -2-methyl-6- (julolidin-4-yl-vinyl) -4H-pyran, bis (2-2-hydroxyphenyl) -phenyl-1, 3-thiazole ato) -Zn complex, bis (2- (2-hydroxyphenyl) -phenyl-1, 3-oxadiazole ato) -Zn complex, tris (8-hydroxy-quinoline ato) -Al complex, tris (8-hydroxy-4-methyl-quinoline ato) -Al complex, or tris (5-chloro-8-hydroxy-quinoline ato) -Al complex.

60. The composition of claim 57, being a primer layer composition comprising a thermoplastic, thermoset, or precursor thereof and a charge transport material.

61. The composition of claim 60, wherein the thermoplastic or thermoset material is selected from the group consisting of polyvinyl butyral, cellulose acetate butyrate, polyalkylacrylates, polyalkylmethacrylates, polyethers, polyurethanes, polyamides, polyesters, polycarbonates, multifunctional acrylates or methacrylates, styrene, vinyl ethers, epoxides, and oligomers or polymers thereof.

62. The composition of claim 57, being a sealant layer composition comprising a polymeric material and a charge transport material.

63. The composition of claim 62, wherein the polymeric material is selected from the group consisting of thermoplastic elastomers, multivalent acrylates or methacrylates, cyanoacrylates, multivalent vinyl compounds including styrene, vinylsilanes, vinyl ethers, multivalent epoxides, multivalent isocyanates, multivalent allyl compounds, and oligomers or polymers containing crosslinkable functional groups.

64. The composition of claim 57, being an adhesive layer composition comprising an adhesive material and a charge transport material.

65. The composition of claim 64, wherein the binder material is selected from the group consisting of polyacrylates, styrene-butadiene copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, polyvinyl butyral, cellulose acetate butyrate, polyvinyl pyrrolidone, polyurethanes, polyamides, ethylene-vinyl acetate copolymers, epoxides, multifunctional acrylates, vinyl compounds, vinyl ethers, and oligomers, polymers, and copolymers thereof.

66. A composition according to claim 57, wherein the amount of charge transport material is from 0.1 to 30% by weight based on the total solids content of the electrode protective layer.

67. A composition according to claim 66, wherein the amount of charge transport material is from 2 to 20% by weight based on the total solids content of the electrode protective layer.

68. Use of a high absorbance dye or pigment, or conductive particles, or a charge transport material, or a combination thereof, to improve the performance of an electrophoretic display.

69. An electrophoretic display comprising at least one electrode protective layer formed from a composition comprising a high absorbance dye or pigment, or conductive particles, or charge transport material, or a combination thereof.

70. An electrophoretic display according to claim 69 prepared using microcup technology.