Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/165—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field
  • G02F1/1675—Constructional details
  • G02F1/1679—Gaskets; Spacers; Sealing of cells; Filling or closing of cells
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/0009—Materials therefor
  • G02F1/0018—Electro-optical materials
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/165—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field
  • G02F1/166—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect
  • G02F1/167—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect by electrophoresis
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L21/00—Compositions of unspecified rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L53/02—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08L9/06—Copolymers with styrene
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/133305—Flexible substrates, e.g. plastics, organic film
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1334—Constructional arrangements; Manufacturing methods based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/165—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field
  • G02F1/1675—Constructional details
  • G02F1/16757—Microcapsules
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/165—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field
  • G02F1/1675—Constructional details
  • G02F2001/1678—Constructional details characterised by the composition or particle type
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
  • G02F2201/50—Protective arrangements
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F2202/00—Materials and properties
  • G02F2202/02—Materials and properties organic material
  • G02F2202/022—Materials and properties organic material polymeric
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F2202/00—Materials and properties
  • G02F2202/02—Materials and properties organic material
  • G02F2202/022—Materials and properties organic material polymeric
  • G02F2202/023—Materials and properties organic material polymeric curable
  • G02F2202/025—Materials and properties organic material polymeric curable thermocurable

Definitions

• This invention relates to flexible displays. More specifically, in one aspect this invention relates to electro-optic displays containing encapsulated electro-optic media.
• Electro-optic displays may be utilized in various applications that require light- weight materials and low power consumption. There is also growing demand for flexible or foldable electro-optic displays. While electro-optic displays may include flexible layers or substrates, such displays can be damaged under extreme stress, particularly displays that incorporate encapsulated electro-optic media. Such failure may occur by mechanical rupture of the capsule wall. Rupture results in the internal phase of the capsules migrating within the display. If a lamination adhesive layer is present adjacent to the electro-optic medium, there is a risk of the internal phase dissolving this adhesive layer and leaving behind as an optically inactive area of the display, which causes visual defects in any image thereafter written on the display.
• an electro-optic medium may comprise a continuous phase comprising a binder and a discontinuous phase comprising electro-optic material, wherein the binder comprises an elastomer having a Young’s modulus less than 25 MPa.
• Figure 1 is a cross-sectional side view of an electro-optic display according to a first embodiment of the present invention.
• Figure 2 is a cross-sectional side view of the electro-optic display of Figure 1 in a folded condition.
• the various embodiments of the present invention comprise an electro-optic medium that may be incorporated into a flexible or foldable display.
• the electro- optic medium may comprise a plurality of capsules and a binder.
• the binder may include one or more elastomers having a Young’s modulus less than 25 MPa.
• elastomer means a macromolecular material that returns rapidly to approximately its initial dimensions and shape after substantial deformation by a weak stress and release of the stress.
• the capsules may encapsulate various kinds of materials capable of switching optical states, such as an electrophoretic fluid that comprises a plurality of charged particles dispersed in a suspending fluid and capable of moving upon application of an electric field to the suspending fluid.
• the electro-optic medium may be incorporated into a laminated flexible electro-optic display having an outer light-transmissive protective layer and conductive material on either side of the electro-optic medium.
• the conductive material on at least one side of the electro-optic medium may also be light-transmissive.
• the opposing side of the display relative to the outer protective layer may also include a substrate.
• optical property is typically color perceptible to the human eye, it may be another optical property, such as optical transmission, reflectance, luminescence or, in the case of displays intended for machine reading, pseudo-color in the sense of a change in reflectance of electromagnetic wavelengths outside the visible range.
• solid electro-optic displays Some electro-optic materials are solid in the sense that the materials have solid external surfaces, although the materials may, and often do, have internal liquid- or gas-filled spaces. Such displays using solid electro-optic materials may hereinafter for convenience be referred to as "solid electro-optic displays".
• solid electro-optic displays includes rotating bichromal member displays, encapsulated electrophoretic displays, microcell electrophoretic displays and encapsulated liquid crystal displays.
• One type of electro-optic display is a rotating bichromal member type as described, for example, in U.S. Patents Nos. 5,808,783; 5,777,782; 5,760,761; 6,054,071 6,055,091; 6,097,531; 6,128,124; 6,137,467; and 6,147,791 (although this type of display is often referred to as a "rotating bichromal ball" display, the term “rotating bichromal member” is preferred as more accurate since in some of the patents mentioned above the rotating members are not spherical).
• Such a display uses a large number of small bodies (typically spherical or cylindrical) which have two or more sections with differing optical characteristics, and an internal dipole.
• Electrophoretic display Another type of electro-optic display, which has been the subject of intense research and development for a number of years, is the particle-based electrophoretic display, in which a plurality of charged particles move through a fluid under the influence of an electric field. Electrophoretic displays can have attributes of good brightness and contrast, wide viewing angles, state bistability, and low power consumption when compared with liquid crystal displays. Nevertheless, problems with the long-term image quality of these displays have prevented their widespread usage. For example, particles that make up electrophoretic displays tend to settle, resulting in inadequate service-life for these displays.
• electrophoretic media require the presence of a fluid.
• this fluid is a liquid, but electrophoretic media can be produced using gaseous fluids; see, for example, Kitamura, T., et al., "Electrical toner movement for electronic paper-like display", IDW Japan, 2001, Paper HCS1-1, and Yamaguchi, Y., et al., "Toner display using insulative particles charged triboelectrically", IDW Japan, 2001, Paper AMD4-4). See also U.S. Patents Nos. 7,321,459 and 7,236,291.
• Such gas-based electrophoretic media appear to be susceptible to the same types of problems due to particle settling as liquid- based electrophoretic media, when the media are used in an orientation which permits such settling, for example in a sign where the medium is disposed in a vertical plane. Indeed, particle settling appears to be a more serious problem in gas-based electrophoretic media than in liquid- based ones, since the lower viscosity of gaseous suspending fluids as compared with liquid ones allows more rapid settling of the electrophoretic particles.
• Encapsulated electrophoretic media comprise numerous small capsules, each of which itself comprises an internal phase containing electrophoretically-mobile particles in a fluid medium, and a capsule wall surrounding the internal phase. Typically, the capsules are themselves held within a polymeric binder to form a coherent layer positioned between two electrodes.
• the charged particles and the fluid are not encapsulated within microcapsules but instead are retained within a plurality of cavities formed within a carrier medium, typically a polymeric film.
• the technologies described in these patents and applications include: (a) Electrophoretic particles, fluids and fluid additives; see for example U.S. Patent Nos. 7,002,728 and 7,679,814;
• polymer-dispersed electrophoretic media are regarded as sub-species of encapsulated electrophoretic media.
• electro-optic media may also be used in the displays of the present invention.
• An encapsulated electrophoretic display typically does not suffer from the clustering and settling failure mode of traditional electrophoretic devices and provides further advantages, such as the ability to print or coat the display on a wide variety of flexible and rigid substrates.
• printing is intended to include all forms of printing and coating, including, but without limitation: pre-metered coatings such as patch die coating, slot or extrusion coating, slide or cascade coating, curtain coating; roll coating such as knife over roll coating, forward and reverse roll coating; gravure coating; dip coating; spray coating; meniscus coating; spin coating; brush coating; air knife coating; silk screen printing processes; electrostatic printing processes; thermal printing processes; ink jet printing processes; electrophoretic deposition (See U.S. Patent No. 7,339,715); and other similar techniques.)
• pre-metered coatings such as patch die coating, slot or extrusion coating, slide or cascade coating, curtain coating
• roll coating such as knife over roll coating, forward and reverse roll coating
• gravure coating dip coating
• spray coating meniscus coating
• spin coating brush coating
• an encapsulated electro-optic medium typically comprises capsules disposed in a polymeric binder, which serves to form the discrete capsules into a coherent layer.
• the continuous phase in a polymer-dispersed electrophoretic medium serves similar functions.
• the present invention seeks to provide improved binder compositions to reduce or eliminate the likelihood of rupture and leakage of the encapsulated electro-optic media that may result from the stress applied during bending a flexible display.
• the binder systems according to the various embodiments of the present invention preferably have sufficient strength to withstand the stresses encountered when bending to very small radii (i.e., ⁇ 7mm).
• the binder system include an energy-dissipating elastomer.
• elastomers are typically phase-separated polymers, such as block-copolymers and thermoplastic polymers.
• the elastomers incorporated in the binder may have a Young’s modulus less than about, with increasing preference in the order listed, 25 MPa, 20 MPa, 15 MPa, 10 MPa, 5 MPa, and 1 MPa.
• the elastomers incorporated in the various embodiments of the present invention may at a temperature between -10 and +40° C have a Young's storage modulus E' between 0.1 MPa and 1000 MPa, a loss factor greater than 0.3, and a shear storage modulus G' between 0.1 MPa and 500 MPa in the frequency range 0 to 500 Hz.
• the elastomer may also have a glass transition temperature in a range from -125 to +20° C.
• the elastomers in the binder system are also preferably immiscible in the electro-optic material. Furthermore, with respect to electro-optic material encapsulated within capsules, the elastomers are preferably compatible with the capsule materials, i.e. the elastomers will not repel the capsule walls.
• Examples of elastomers that may be included in the various embodiments of the present invention include, but are not limited to, synthetic and natural rubbers, polybutadiene, polyisoprene, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene, styrene- isoprene/butadiene-styrene block copolymers, styrene-ethylene/butylene-stryene block copolymers, styrene-ethylene/propylene block copolymers, styrene-ethylene/propylene- styrene block copolymers, isoprene-butadiene block copolymers, butadiene-isoprene-styrene block copolymers, styrene-isobutylene-styrene block copolymers, butyl rubber
• the various embodiments of the present invention have a weight ratio of binder to electro-optic material within the electro-optic medium that is at least, with increasing preference in the order given, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.40, 0.45, 0.50, 0.55, and 0.60.
• the binder systems according to the various embodiments of the present invention may further comprise one or more non-elastomeric polymers.
• non-elastomeric polymers that may be incorporated into the various embodiments of the present invention include, but are not limited to, polysaccharides, polyvinyl alcohols, poly(N- vinylpyrrolidone), polyethylene glycol, poly(2-hydroxyethyl acrylate), polymers of bisphenol A diglycidyl ether, latices of polyurethanes optionally compounded with one or more of acrylics, polyesters, polycarbonates, silicones, an epoxidized vegetable oil fatty acid, an epoxidized ester of a vegetable oil fatty acid, and combinations thereof.
• the binder systems comprising a blend of materials according to the various embodiments of the present invention include a weight ratio of elastomer to non-elastomeric polymer, with increasing preference in the order given, of at least 0.05, 0.10, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, and not more than, with increasing preference in the order given, 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50.
• Some level of crosslinking of the binder system may be desired in certain applications to ensure that the layers maintain dimensional stability and resist creep during bending when incorporated into a laminated displays having various layers.
• “creep” means that certain materials, such as the binder system or adhesive, within a flexible laminated display tend to undergo fluid flow when flexed with the result that the electro-optic medium and/or other layers move slightly relative to the backplane.
• the display is a color display in which a color filter array is disposed on the opposed side of the electro-optic medium from the backplane, since in such a display the various color stripes or other units of the color filter array need to be aligned with the pixel electrodes or serious color distortion may occur in the displayed image.
• a display in which two adjacent pixel electrodes are aligned with red and blue color filter elements. If the color filter array creeps relative to the backplane such that the pixel electrode originally aligned with the red element is now aligned with half the red element and half the blue element, it will readily be apparent that the colors of the displayed image will differ substantially from that intended.
• Cross-linking of the binder systems according to the various embodiments of the present invention may be achieved by using cross-linkable elastomers (see for example, U.S. Patent No. 5,262,232) or blending the elastomers with cross-linkable non-elastomeric polymers (see for example, U.S. Patent No. 5,331,062).
• the degree of cross-linking may therefore be varied within the binder system to provide both energy-dissipating properties and creep resistance for a given application.
• Crosslinking may be physical and/or chemical.
• additives may be incorporated into the binder systems according to the various embodiments of the invention to improve their visco-elastic or other properties.
• additives include, but are not limited to, stabilizers/antioxidants (e.g. sterically hindered phenols and/or thioethers, sterically hindered aromatic amines and the like), tackifying resins (e.g.
• plasticizers such as C1-10 alkyl esters of dibasic acids (e.g., phthalate esters), diaryl ethers, benzoates of polyalkylene glycols, organic phosphates, and alkylsulfonic acid esters of phenol or cresol, fillers (e.g. nanoclays, carbon nanotubes, chalks, talc, calcium carbonate, carbon black, calcium-magnesium carbonates, barite, clay, mica, silicates), and waxes.
• plasticizers such as C1-10 alkyl esters of dibasic acids (e.g., phthalate esters), diaryl ethers, benzoates of polyalkylene glycols, organic phosphates, and alkylsulfonic acid esters of phenol or cresol
• fillers e.g. nanoclays, carbon nanotubes, chalks, talc, calcium carbonate, carbon black, calcium-magnesium carbonates, barite, clay, mica, silicates
• the binder systems may further comprise a curing agent and optional curing accelerators.
• curing agents include, but are not limited to, substances capable of inducing free radical reactions, for example organic peroxides including ketone peroxides, diacyl peroxides, peresters, perketals, hydroperoxides and others such as cumene hydroperoxide, bis(tert-butylperoxy) diisopropyl benzene, di(-2-tert-butyl peroxyisopropyl benzene), l,l-di-tert-butylperoxy-3,3,5- trimethylcyclohexane, dicumyl peroxide, t-butylperoxy-benzoate, di-alkyl peroxydicarbonates, di-peroxyketals (such as l,l-d i-tert-butylperoxy-3,3,5- trimethylcyclohexane
• the electro-optic medium according to the various embodiments of the present invention may be incorporated into flexible electro-optic displays.
• An electro-optic display normally comprises a layer of electro-optic material and at least two other layers disposed on opposed sides of the electro-optic material, one of these two layers being an electrode layer.
• both the layers are electrode layers, and one or both of the electrode layers are patterned to define the pixels of the display.
• one electrode layer may be patterned into elongate row electrodes and the other into elongate column electrodes running at right angles to the row electrodes, the pixels being defined by the intersections of the row and column electrodes.
• one electrode layer has the form of a single continuous electrode and the other electrode layer is patterned into a matrix of pixel electrodes, each of which defines one pixel of the display.
• one electrode layer has the form of a single continuous electrode and the other electrode layer is patterned into a matrix of pixel electrodes, each of which defines one pixel of the display.
• only one of the layers adjacent the electro-optic layer comprises an electrode, the layer on the opposed side of the electro-optic layer typically being a protective layer intended to prevent the movable electrode damaging the electro-optic layer.
• the flexible display may include a light- transmissive protective layer 10 providing a viewing surface.
• the protective layer 10 is preferably flexible and coated with a first layer of conductive material 12, which is also light- transmissive.
• a layer of electro-optic medium 14 containing the binder system 13 and encapsulated media 11 is then applied to the conductive material 12.
• An optional second layer of conductive material 16 may be included between the electro-optic medium 14 and a substrate 18.
• the substrate 18 may be a backplane and the second layer of conductive material 16 may include a plurality of conductors.
• the substrate 18 and second layer of conductive material 16 may be light-transmissive to provide a dual-sided display.
• the substrate 18 may be a release sheet that is removed prior to subsequent lamination procedures.
• the display illustrated in Figures 1 and 2 may also include one or more layers of lamination adhesive (not shown) between any of the two layers within the stack.
• the binder system 13 should be sufficiently energy-dissipating, such that flexing the display will not rupture the encapsulated media 11 present within the bended area of the display, even when bended to a relatively small radii.
• an electro-optic display normally involves at least one lamination operation.
• an encapsulated electrophoretic display in which an encapsulated electrophoretic medium comprising capsules in a binder is coated on to a flexible substrate comprising indium-tin-oxide (ITO) or a similar conductive coating (which acts as one electrode of the final display) on a plastic film, the capsules/binder coating being dried to form a coherent layer of the electrophoretic medium firmly adhered to the substrate.
• ITO indium-tin-oxide
• a similar conductive coating which acts as one electrode of the final display
• a backplane containing an array of pixel electrodes and an appropriate arrangement of conductors to connect the pixel electrodes to drive circuitry, is prepared.
• the substrate having the capsule/binder layer thereon is laminated to the backplane using a lamination adhesive.
• a lamination adhesive A very similar process can be used to prepare an electrophoretic display usable with a stylus or similar movable electrode by replacing the backplane with a simple protective layer, such as a plastic film, over which the stylus or other movable electrode can slide.
• the backplane is itself flexible and is prepared by printing the pixel electrodes and conductors on a plastic film or other flexible substrate.
• the obvious lamination technique for mass production of displays by this process is roll lamination using a lamination adhesive. Similar manufacturing techniques can be used with other types of electro-optic displays.
• a microcell electrophoretic medium or a rotating bichromal member medium may be laminated to a backplane in substantially the same manner as an encapsulated electrophoretic medium.
• U.S. Patent Application Publication No. 2007/0109219 also describes various methods designed for high volume manufacture of electro-optic displays using inverted front plane laminates; preferred forms of these methods are "multi-up" methods designed to allow lamination of components for a plurality of electro-optic displays at one time.
• Electro-optic displays are often costly; for example, the cost of the color LCD found in a portable computer is typically a substantial fraction of the entire cost of the computer. As the use of electro-optic displays spreads to devices, such as cellular telephones and personal digital assistants (PDA's), much less costly than portable computers, there is great pressure to reduce the costs of such displays.
• PDA's personal digital assistants
• the light-transmissive electrically-conductive layer will be carried on a light-transmissive substrate, which is preferably flexible, in the sense that the substrate can be manually wrapped around a drum (say) 10 inches (254 mm) in diameter without permanent deformation.
• the term "light- transmissive" is used in this patent and herein to mean that the layer thus designated transmits sufficient light to enable an observer, looking through that layer, to observe the change in display states of the electro-optic medium, which will normally be viewed through the electrically-conductive layer and adjacent substrate (if present); in cases where the electro- optic medium displays a change in reflectivity at non-visible wavelengths, the term "light- transmissive" should of course be interpreted to refer to transmission of the relevant non-visible wavelengths.
• the substrate will typically be a polymeric film, and will normally have a thickness in the range of about 1 to about 25 mil (25 to 634 pm), preferably about 2 to about 10 mil (51 to 254 pm).
• the electrically-conductive layer is conveniently a thin metal or metal oxide layer of, for example, aluminum or ITO, or may be a conductive polymer.
• PET Poly(ethylene terephthalate)
• PET Poly(ethylene terephthalate) films coated with aluminum or ITO are available commercially, for example as "aluminized Mylar” ("Mylar” is a Registered Trade Mark) from E.I. du Pont de Nemours & Company, Wilmington DE, and such commercial materials may be used with good results in the front plane laminate.
• Assembly of an electro-optic display using such a front plane laminate may be effected by removing the release sheet from the front plane laminate and contacting the adhesive layer with the backplane under conditions effective to cause the adhesive layer to adhere to the backplane, thereby securing the adhesive layer, layer of electro-optic medium and electrically-conductive layer to the backplane.
• This process is well-adapted to mass production since the front plane laminate may be mass produced, typically using roll-to-roll coating techniques, and then cut into pieces of any size needed for use with specific backplanes.
• U.S. Patent No. 7,561,324 describes a so-called "double release sheet" which is essentially a simplified version of the front plane laminate of the aforementioned U.S. Patent No. 6,982,178.
• One form of the double release sheet comprises a layer of a solid electro-optic medium sandwiched between two adhesive layers, one or both of the adhesive layers being covered by a release sheet.
• Another form of the double release sheet comprises a layer of a solid electro-optic medium sandwiched between two release sheets.
• Both forms of the double release film are intended for use in a process generally similar to the process for assembling an electro-optic display from a front plane laminate already described, but involving two separate laminations; typically, in a first lamination the double release sheet is laminated to a front electrode to form a front sub-assembly, and then in a second lamination the front sub-assembly is laminated to a backplane to form the final display, although the order of these two laminations could be reversed if desired.
• U. S. Patent No. 7,839,564 describes a so-called "inverted front plane laminate", which is a variant of the front plane laminate described in the aforementioned U.S. Patent No. 6,982,178.
• This inverted front plane laminate comprises, in order, at least one of a light- transmissive protective layer and a light-transmissive electrically-conductive layer; an adhesive layer; a layer of a solid electro-optic medium; and a release sheet.
• This inverted front plane laminate is used to form an electro-optic display having a layer of lamination adhesive between the electro-optic layer and the front electrode or front substrate; a second, typically thin layer of adhesive may or may not be present between the electro-optic layer and a backplane.
• Such electro-optic displays can combine good resolution with good low temperature performance.
• Electrophoretic media and displays tend to be mechanically robust, as compared with, for example, liquid crystal displays, which require transparent, typically glass, substrates on both sides of the liquid crystal medium.
• Several of the aforementioned E Ink patents and applications describe processes for producing electrophoretic displays in which an electrophoretic medium is coated on to a flexible plastic substrate provided with an electrically conductive layer, and the resultant electrophoretic medium/substrate sub-assembly is laminated to a backplane containing a matrix of electrodes to form the final display.
• the aforementioned U.S. Patent No. 6,825,068 describes a backplane useful in an electrophoretic display and based upon a stainless steel foil coated with a polyimide. Such technologies can produce flexible electrophoretic displays much less susceptible to breakage than glass-based liquid crystal displays.

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• 2019
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