WO2013191707A1 - Encres comprenant des particules de colorant ayant des dispersants attachés de façon covalente - Google Patents

Encres comprenant des particules de colorant ayant des dispersants attachés de façon covalente Download PDF

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Publication number
WO2013191707A1
WO2013191707A1 PCT/US2012/043778 US2012043778W WO2013191707A1 WO 2013191707 A1 WO2013191707 A1 WO 2013191707A1 US 2012043778 W US2012043778 W US 2012043778W WO 2013191707 A1 WO2013191707 A1 WO 2013191707A1
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Prior art keywords
pigment
group
block
dispersant
particles
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PCT/US2012/043778
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English (en)
Inventor
Qin Liu
Zhang-Lin Zhou
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Hewlett-Packard Development Company, L.P.
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Application filed by Hewlett-Packard Development Company, L.P. filed Critical Hewlett-Packard Development Company, L.P.
Priority to PCT/US2012/043778 priority Critical patent/WO2013191707A1/fr
Priority to TW102116665A priority patent/TW201402720A/zh
Publication of WO2013191707A1 publication Critical patent/WO2013191707A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/02—Printing inks
    • C09D11/10—Printing inks based on artificial resins
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/02—Printing inks
    • C09D11/03—Printing inks characterised by features other than the chemical nature of the binder
    • C09D11/033—Printing inks characterised by features other than the chemical nature of the binder characterised by the solvent
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/02—Printing inks
    • C09D11/03—Printing inks characterised by features other than the chemical nature of the binder
    • C09D11/037—Printing inks characterised by features other than the chemical nature of the binder characterised by the pigment
    • 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
    • G02F1/1347—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or 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
    • G02F1/01—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

Definitions

  • Electrophoretic or electrokinetic displays are an important approach to this type of medium. Electrophoretic/kinetic actuation relies on particles moving under the influence of an electric field, so the desired particles must exhibit good dispersibility and charge properties in non-polar dispersing media. Non- polar dispersing media are desirable because they help minimize the leakage currents in electrophoretic/kinetic devices.
  • FIG. 1 depicts a cross-sectional view of an example of a stacked electro-optical display.
  • FIG. 2 illustrates a cross-sectional view of one example of a lateral electro-optical display.
  • FIG. 3 is a flow chart depicting an example of a process used to form block copolymers that may be used, for example, in the electro-optical display of FIGS. 1 and 2.
  • Grayscale applies to both black and white images and monochromatic color images. Grayscale refers to an image including different shades of a single color produced by controlling the density of the single color within a given area of a display.
  • the term “over” is not limited to any particular orientation and can include above, below, next to, adjacent to, and/or on.
  • the term “over” can encompass intervening components between a first component and a second component where the first component is “over” the second component.
  • adjacent is not limited to any particular orientation and can include above, below, next to, and/or on.
  • adjacent can encompass intervening components between a first component and a second component where the first component is “adjacent" to the second component.
  • electrophoresis As used herein, the term "electronic ink display” is a display that forms visible images using one or more of electrophoresis, electro-convection, electro-osmosis, electrochemical interactions, and/or other electrokinetic phenomena.
  • a bi-state display cell having a dark state and a clear state is provided by an electronic ink with charged colorant particles in an optically transparent fluid.
  • a clear state is achieved when the colorant particles are compacted and a colored state is achieved when the colorant particles are spread.
  • An electronic ink with charged white particles in a colored fluid enables white and spot-color states, with the color of the colored state depending on the color of the fluid.
  • the ink fluid is colored by a dye, nanopar- ticle colorants, pigments, or other suitable colorants.
  • a white state is achieved when the white particles are spread and held in proximity to the surfaces closest to the viewer, and a colored state is achieved when the white particles are compacted to allow absorption by the colorant fluid and subsequent reflection by a diffuse reflector in the back of the cell, or when the white particles are distributed throughout the colorant fluid to backscatter the light that has not been absorbed by the colorant fluid.
  • a tri-state display cell is provided.
  • An electrophoretic display cell may include a three-dimensional architecture to provide a clear optical state.
  • the geometrical shape of the display cell has narrowing portions in which electrophoretically/- electrokinetically translated colorant particles collect and compact in response to appropriate bias conditions applied to driving electrodes on opposite sides of the display cell.
  • the three-dimensional structure of the display cell introduces additional control of electrophoretically/electrokinetically moving colorant par- tides. As a result, desired functionalities can be achieved with a more stable electrophoretic/kinetic ink that resists irreversible agglomeration of the particles, but maintains its ability to both disperse and collect and compact the particles.
  • the driving electrodes are passivated with a dielectric layer, thus eliminating the possibility of electrochemical interactions through the driving electrodes from di- rect contact with the electrophoretic ink.
  • the driving electrodes are not passivated, thus allowing electrochemical interactions with the electrophoretic/kinetic ink.
  • FIG. 1 An example of a stacked device architecture is shown in FIG. 1. This configuration allows stacking of colored layers for electrophoretic/kinetic dis- plays.
  • FIG. 1 illustrates a cross-sectional view of one example of stacked electro-optical display 100.
  • Electro-optical display 100 includes a first display element 102a, a second display element 102b, and a third display element 102c.
  • Third display element 102c is stacked on second display element 102b, and second display element 102b is stacked on first display element 102a.
  • Each display unit includes a first substrate 104, a first electrode 106, a dielectric layer 108 including reservoir or recess regions 110, thin layers 112, a display cell 114, a second electrode 116, and a second substrate 118.
  • Display cell 114 is filled with a carrier fluid 120 with colorant particles 122.
  • thin layers 112 may be opaque. In other examples, thin layers 112 may be transparent.
  • First display element 102a includes thin layers 1 12a self-aligned within recess regions 110. First display element 102a also includes colorant particles 122a having a first color (e.g., cyan) for a full color electro-optical display.
  • Second display element 102b includes thin layers 112b self- aligned within recess regions 1 10. Second display element 102b also includes colorant particles 122b having a second color (e.g., magenta) for a full color electro-optical display.
  • second color e.g., magenta
  • Third display element 102c includes thin layers 1 12c self-aligned within recess regions 110. Third display element 102c also includes colorant particles 122c having a third color (e.g., yellow) for a full color electro-optical display. In other examples, colorant particles 122a, 122b, and 12c may include other suitable colors for providing an additive or subtractive full color electro- optical display.
  • colorant particles 122a, 122b, and 12c may include other suitable colors for providing an additive or subtractive full color electro- optical display.
  • first display element 102a, second display element 102b, and third display element 102c are aligned with each other.
  • thin layers 1 12a, 1 12b, and 1 12c are also aligned with each other.
  • recess regions 1 10 and self-aligned thin layers 112a, 1 12b, and 1 12c of each display element 102a, 102b, and 102c, respectively are aligned, the clear aperture for stacked electro- optical display 100 is improved compared to a stacked electro-optical display without such alignment.
  • first display element 102a, second display element 102b, and third display element 102c may be offset from each other.
  • thin layers 1 12a, 112b, and 112c are also offset from each other.
  • recess regions 1 10 and self-aligned thin layers 1 12a, 1 12b, and 1 12c are just a fraction of the total area of each display element 102a, 102b, and 102c, respectively, the clear aperture for stacked electro-optical display 100 remains high regardless of the alignment between display elements 102a, 102b, and 102c. As such, the process for fabricating stacked electro-optical display 100 is simplified.
  • the self-aligned thin layers 1 12a, 1 12b, and 112c prevent tinting of each display element due to colorant particles 122a, 122b, and 122c, respectively, in the clear optical state. Therefore, a stacked full color electro-optical display having a bright, neutral white state and precise color control is provided.
  • this architecture enables both clear and co- lored states.
  • developing electronic inks that work in this architecture has been challenging.
  • the materials used in presently-available commercial products do not work in this architecture, since they do not provide clear states.
  • Significant progress toward developing working electronic inks for this architecture has been made; see, e.g., PCT/US2009/060971 ("Electronic Inks");
  • FIG. 2 illustrates a cross-sectional view of one example of lateral electro-optical display 200.
  • Electro-optical display 200 includes a display element 202a. Additional display elements may be disposed laterally in the x and y directions, as side-by-side sub-pixels or segments, with each display element containing inks having colorant particles 122 of different colors, or having black colorant particles that are collected to reveal patterned color filters or wavelength-selective reflectors below.
  • Each display element 202a is similar to electro-optical display 100a previously described and illustrated with reference to FIG. 1.
  • Each display element 202a may include circular shaped thin layers 1 10a self-aligned within recess regions 108.
  • Each display element 202a may also include colorant particles 122 having a color (e.g., cyan, magenta, yellow, black, or white) for a full color electro-optical display.
  • colorant particles 122 may include other suitable colors for providing an additive or subtractive full color electro-optical display.
  • novel stable inks specifically, electronic inks, based on utilizing block copolymers grafted onto pigment colorant particles are disclosed.
  • the block copolymers include at least disper- sant on at least one of the blocks, as further described below. While tri-block copolymers are specifically disclosed, the teachings may also be applied to di- block copolymers. It is noteworthy that the order of either di-block or tri-block copolymers can be interchangeable.
  • methods of grafting particles with block copolymers via surface initiated (living) polymerization techniques such as atom transfer radical polymerization (ATRP) or reversible addition-fragmentation chain transfer (RAFT).
  • ATRP atom transfer radical polymerization
  • RAFT reversible addition-fragmentation chain transfer
  • Functionalized tri-block copolymers are designed to have three portions that are grafted to the particle or subsequent polymer ends in a stepwise fashion.
  • the first and third blocks that comprise the inner and outer ends of the polymer chain respectively each contain bulky organic groups to help facilitate the solubility of such functionalized polymers in the solvent and provide a steric stabilization to the resulting particle dispersion.
  • the second middle block portion of the polymer chain contains either acidic or basic functionalized side groups that facilitate charging of the particle.
  • Such stable and charged particle dispersions can be used for a variety of applications such as pigments as colorants in electrophoretic/electrokinetic displays, particles to improve the bistability of anisotropic fluid electrophoretic displays (such as electrophoretic colorant particles in a liquid crystal host), and as field-addressable dielectric media for tuning the local index of refraction near an array of metallic nanostructures in order to tune the optical spectral response of plasmon resonance effect generated by the nanostructure array.
  • Either one or both of the inner or outer blocks may include the dispersant.
  • Functionalized di-block copolymers are designed to have two portions that are grafted to the particle or subsequent polymer ends in a step-wise fashion.
  • the first block that comprises the inner end of the polymer chain contains bulky organic groups to help facilitate the solubility of such functionalized polymers in the solvent and provide a steric stabilization to the resulting particle dispersion.
  • the second block portion of the polymer chain contains either acidic or basic functionalized side groups that facilitate charging of the particle.
  • the inner block may include the dispersant. It is noted that the order of di-block copo- lymers can be interchangeable.
  • each block copolymer graft comprises a block copolymer having two or three blocks: a first block attached to the pigment particle, a second block attached to the first block, and an optional third block attached to the second block.
  • One of the blocks may contain either a dispersant, a solubiliz- ing and sterically bulky group, or both.
  • Another of the blocks may contain either acidic or basic functionalized side groups that facilitate charging of the pigment particle.
  • the optional block may contain either a dispersant, a solubilizing and sterically bulky group, or both, with the proviso that the dispersant is present on at least one of the blocks identified as having the dispersant.
  • the disclosure herein provides methods of dispersing particles in non-polar solvents using novel functionalized tri-block copolymers grafted in a step-wise process.
  • the resulting particle polymer encapsulation minimizes the need for additional surfactants or charge directors.
  • Electronic inks based on such tri-block copolymer encapsulated particles are robust, because the tri- block copolymer composition is covalently bonded to the particle surfaces.
  • the independent design of the various polymer blocks provides some design flex- ibility for the control of a stable particle dispersion and the charge characteristics for a particle species. This can have a positive influence on the switching " speed performance and lifetime of electronic inks.
  • each species is a differ- ent color particle or pigment type which can be independently controlled in the same ink volume.
  • the disclosed invention employs the designed steric stabilization feature of the polymer blocks to prevent agglomeration and precipitation of the oppositely charged colorant species.
  • ATRP Atom Transfer Radical Polymerization
  • RAFT Revers- ible Addition-Fragmentation chain Transfer
  • living polymerization is a form of addition polymerization where the ability of a growing polymer chain to terminate has been removed. This can be accomplished in a variety of ways. Chain termination and chain transfer reactions are absent and the rate of chain initiation is also much larger than the rate of chain propagation. The result is that the polymer chains grow at a more constant rate than seen in traditional chain polymerization and their lengths remain very similar (i.e. they have a very low polydispersity index). Living polymerization is a popular method for synthesizing block copolymers since the polymer can be synthesized in stages, each stage containing a differ- ent monomer. Additional advantages are predetermined molar mass and control over end-groups.
  • the uniform polymer chain growth which leads to low po- lydispersity, stems from use of a transition metal-based catalyst.
  • This catalyst provides an equilibrium between active, and therefore propagating, polymer and an inactive form of the polymer; known as. the dormant form. Since the dormant state of the polymer is vastly preferred in this equilibrium, side reactions are suppressed. This equilibrium in turn lowers the concentration of propagating radicals, therefore suppressing unintentional termination and controlling molecu- lar weights.
  • ATRP reactions are very robust in that they are tolerant of many functional groups such as allyl, amino, epoxy, hydroxy, and vinyl groups present in either the monomer or the initator. ATRP methods may also be advantageous due to the ease of preparation, commercially available and inexpensive catalysts (copper complexes), pyridine based ligands and initiators (alkyl halides).
  • RAFT is a type of living polymerization involving a conventional radical polymerization in the presence of a reversible chain transfer reagent. Like other living polymerizations, there is no termination step in the RAFT process. It is a very versatile method to form low polydispersity polymer from monomers capable of radical polymerization. The reaction is usually done with a dithioester. The dithio compound must have a good homolytic leaving group, R, whose radical must be capable of initiating a polymerization reaction. There are four steps in raft polymerization: initiation, addition-fragmentation, reinitiation and equilibration.
  • a step-wise method is de- scribed for grafting novel functional block copolymers containing known disper- sants onto a particle or pigment surface and the formulation of stable electronic inks based on such surface-modified pigments.
  • the first step in the process is to convert known dispersants to polymerizable macromonomers. Shown in " Scheme 1 are examples of the conversion steps. [0039] Scheme 1 depicts methods of converting known dispersants to polymerizable macromonomers. Reaction of commercially-available 2-methyl-2- propenoic acid isocyanatoalkyi ester (1) with commercially available dispersant 2 or 3 gives polymerizable macromonomer 4 and 5, respectively.
  • n is an integer from 1 to
  • Scheme 2 shows the structure of functional copolymers that contains known dispersants, chargeable groups, and another portion of bulky steric stabilization segment: [0044] Scheme 2 block copolymer
  • SGi and SG 2 each independently represent a known dis- persant and/or a solublizing and sterically bulky group, which helps to improve the solubility of the polymer and stabilize the nano-composite material.
  • Exam- pies of known dispersants are shown above in Scheme 1.
  • the sterically bulky group may be any of alkyl groups, alkoxy groups, branched alkyl groups, branched alkoxy groups, and substituted phenyl groups.
  • FG represents an oligomer or functional group that provides charging sites/charges to pigment surfaces. It can be an oligomer or monomeric moiety that contains acidic or basic groups.
  • an acidic functional group include hydroxyl, carboxylate, a sulfonic acid, a phosphonic acid, a phosphorous acid, etc.
  • Examples of a basic group include primary amine, secondary amine, tertiary amine, pyridine, imidazoline, etc.
  • oligomers or monomers of (meth)acrylic acid 2-sulfoethyl methacylate, dimethy- lamino ethyl (meth)acrylate, and diethylamino ethyl styrene.
  • (meth)-acrylic (or (meth)acrylate) is intended to cover both acrylic and me- thacrylic (or acrylate and methacrylate), as is generally accepted.
  • the letters x, y, and z are each independently an integer between 1 and about 5,000.
  • FG group is identified above as containing acidic or basic groups. In practice, these groups are frequently in neutralized form, i.e. salt. So, while the description and claims both recite acidic and basic groups, it should be understood that such groups encompass the salt form thereof as well.
  • Scheme 3 shows a general example of a tri-block copolymer that can be grafted onto pigment surfaces, in which three blocks are connected with carbon-carbon single bonds.
  • Scheme 4 shows a few general examples of monomers that can be grafted onto pigment surfaces to provide further stabilizing functions.
  • RL R 2I R3, R4 and R5 are each independently selected from the group consisting of C1-C30 alkyl, C1-C30 alkenyl, C1-C30 alkynyl, C1-C30 aryl, C1-C30 alkoxy, C1-C30 phenoxy, C1-C30 thioalkyl, C1-C30 thioaryl,
  • R6, R 7 , Re, R9 and R10 are each independently selected from the group consisting of hydrogen, C1-C30 alkyl and C1-C30 aryl, and so forth.
  • Ri, R2, R3, R 4 , R5, R6, R7, Re and R9 may or may not be identical.
  • Scheme 4A shows some more specific examples that can be used for making SGi or SG2, in which these monomers are polymerizable macro- monomers from Scheme 1.
  • n 1 to about 500.
  • Scheme 5 shows some examples of monomers that can be grafted onto pigment surfaces to provide chargeable sites to the pigment surfaces.
  • Ri, R 2l R3, R and R 5 are each independently selected from the group consisting of C1-C30 alkyl, C1-C30 alkenyl, C1-C30 alkynyl, C1-C30 aryl, C1 -C30 alkoxy, C1-C30 phenoxy, C1-C30 thioalkyl, C1-C30 thioaryl,
  • R 6 N(R 7 )(R 8 ), C(O)N(R 9 )(R 10 ), F, CI, Br, N0 2l CN, acyl, carboxylate and hydroxy
  • R6, R 7 , Re, R9 and R10 are each independently selected from the group consisting of hydrogen, C1-C30 alkyl and C1-C30 aryl, and so forth.
  • R 1 ( R 2 , R3, R 4l R5, R6, R7, Re and Rg may or may not be identical.
  • Scheme 6 depicts a method of grafting functional block copolymer onto pigment surfaces (grafting from method) using surface-initiated RAFT technology.
  • Coupling reaction of inorganic pigments or metal oxide layer coated organic pigments I with reactive initiator gives initiator linked pigment II.
  • Pigment II undergoes the first surface initiated polymerization with the first block monomer or macromonomer to give the first block grafted pigment III.
  • Pigment III un- dergoes the second surface initiated polymerization with the second block monomer to give two-block polymers grafted pigment IV.
  • Pigment IV undergoes the third surface initiated polymerization with the third block monomer or macromo- nomer to give three-block grafted pigment V.
  • Such tri-block copolymers grafted pigments can be mixed with other dispersants or charge directors to form charged and stable pigment dispersions for electronic ink applications. It is worth noting that one can use two block or three block copolymers containing dispersants to graft pigments.
  • an inorganic pigment or an organic pigment with a metal oxide coating (pigment I) is provided 305.
  • a coupling reaction of pigment I with a reactive initiator is induced 310 to give an initiator-linked pigment II.
  • a first block mo- nomer or macromonomer is attached 315 to the surface of pigment II to give a first block grafted pigment III.
  • a second block monomer (or oligomer) is attached 320 to the first block to give a two-block polymer grafted pigment IV.
  • a third block monomer or macromonomer is attached 325 to the second block to give a three-block polymer grafted pigment V.
  • Scheme 7 describes a specific example of a tri-block copolymer with grafted pigments that bear negative charges (grafting from method) using surface initiated RAFT technology. It describes polystylene, polyacrylic acid ammonium salts and polyisobutylene succinimide polyamines acrylate based tri- block copolymers. Coupling reaction of inorganic pigments or metal oxide layer coated organic pigments I with reactive initiator gives initiator linked pigment II. Pigment II undergoes the first surface initiated polymerization with the first block monomer - substituted styrenes to give the first block - polystyrene grafted pigment III.
  • Pigment III undergoes the second surface initiated polymerization with the second block monomer - acrylic acid to give two-block polymers - po- lystyrene and polyacrylic acid grafted pigment IV.
  • Pigment IV undergoes the third surface initiated polymerization with the third block macromonomer - polyisobutylene succinimide amines acrylate to give three-block polymers - polystyrene, polyacrylic acid ammonium salts and polyisobutylene succinimide polyamines acrylate grafted pigment V.
  • Such tri-block copolymers grafted pigments can be mixed with other dispersants or charge directors to form positively charged and stable pigment dispersions for electronic ink applications. It's worth noting that one can use two block or three block copolymers containing dispersants to graft pigments.
  • R represents sterically bulky group, which helps to improve the solubility of the polymer and stabilize the nano-composite material. It could be any alkyi groups, alkoxy groups, branched alkyi groups and branched alkoxy groups.
  • x, y and z are each independently an integer between 1 and about 5,000.
  • n any integer between 1 and 500.
  • Scheme 8 describes a specific example of a tri-block copolymer with grafted pigments that bear positive charges (grafting from method) using surface initiated RAFT technology. It describes polystyrene, polyacrylic acid ammonium salts and poly(12-hydroxystearic acid) based tri-block copolymers. Coupling reaction of inorganic pigments or metal oxide layer coated organic pigments I with reactive initiator gives initiator linked pigment II. Pigment II undergoes the first surface initiated polymerization with the first block monomer - substituted styrenes to give the first block - polystyrene grafted pigment III.
  • Pigment III undergoes the second surface initiated polymerization with the second block monomer - acrylic acid ammonium salts to give two-block polymers - polystyrene and polyacrylic acid ammonium salts grafted pigment IV.
  • Pigment IV undergoes the third surface initiated polymerization with the third block macromonomer - poly(12-hydroxystearic acid) based acrylate to give three-block polymers - polystyrene, polyacrylic acid and poly(12-hydroxystearic acid) based grafted pigment V.
  • Such tri-block copolymers grafted pigments can be mixed with other dispersants or charge directors to form negatively charged and stable pigment dispersions for electronic ink applications. It is worth noting that one can use two block or three block copolymers containing dispersants to graft pigments.
  • R 2I 3> R4 and R 5 represent sterically bulky groups, which helps to improve the solubility of the polymer and stabilize the nano- composite material. It could be any alkyl groups, alkoxy groups, branched alkyl groups and branched alkoxy groups.
  • n any integer between 1 and 500.
  • reaction schemes depicted above are all directed to the RAFT method.
  • alternate surface-initiated polymerization methods such as ATRP and NMP, may also be employed in the reaction schemes depicted herein.
  • examples of such electronic inks generally include a non-polar carrier fluid (i.e., a fluid having a low dielectric constant k such as, e.g., less than about 20, or, in some cases, less than about 2).
  • a non-polar carrier fluid i.e., a fluid having a low dielectric constant k such as, e.g., less than about 20, or, in some cases, less than about 2.
  • the carrier fluid is a fluid or medium that fills up a viewing area defined in an electronic ink display and is generally configured as a vehicle to carry colorant particles therein.
  • the non-polar carrier fluid includes, for example, one or more non-polar carrier fluids selected from hydro- carbons, halogenated or partially halogenated hydrocarbons, and/or siloxanes.
  • non-polar carrier fluids include perchloroethylene, cyclohexane, dodecane, mineral oil, isoparaffinic fluids, cyclopentasiloxane, cyc- lohexasiloxane, and combinations thereof.
  • the colorant particles are dispersed in the carrier fluid.
  • the term "colorant particles” refers to particles that produce a color.
  • suitable colorant particles include the surface- modified pigment particles described above.
  • the colorant particles are selected from pigment particles that are self-dispersible in the non-polar carrier fluid. It is to be understood, however, that non-dispersible pig- ment particles may otherwise be used so long as the electronic ink includes one or more suitable dispersants.
  • a dispersant may or may not be added to the ink, since the pigment particles contain a dispersant moiety. Simple experimentation will determine whether or not a dispersant is to be added to the ink, in light of the dispersant moieties on the pigment particles.
  • Such dispersants may include hyperdispersants such as those of the SOLSPERSE ® series manufactured by Lubrizol Corp., Wickliffe, OH (e.g., SOLSPERSE ® 3000, SOLSPERSE ® 8000, SOLSPERSE ® 9000, SOLSPERSE® 11200, SOLSPERSE ® 13840, SOLSPERSE® 16000, SOLSPERSE ® 17000, SOLSPERSE ® 18000, SOLSPERSE ® 19000, SOLSPERSE® 21000, and SOLSPERSE ® 27000); various dispersants manufactured by BYK- chemie, Gmbh, Germany, (e.g., DISPERBYK ® 110, DISPERBYK ® 163, DIS- PERBYK® 170, and DISPERBYK® 180); various dispersants manufactured by Evonik Goldschmidt GMBH LLC, Germany, (e.g., TEGO® 630, TEGO 630, TEGO 630,
  • the concentration of pigment in the electronic ink may range from about 0.5 to 20 percent by weight (wt%). In other examples, the concentration of the pigment may range from about 1 to 10 wt%.
  • the concentration of dispersant in the electronic ink may range from about 0.5 to 20 percent by weight (wt%). In other examples, the concentration of the dispersant may range from about 1 to 10 wt%.
  • the carrier fluid makes up the balance of the ink.
  • the term "charge director” refers to a material that, when used, facilitates charging of the colorant particles.
  • the charge director is basic and reacts with the acid-modified colorant particle to negatively charge the particle.
  • the charging of the particle is accomplished via an acid-base reaction between the charge director and the acid-modified particle surface.
  • the charge director may also be used in the electronic ink to prevent undesirable aggregation of the colorant in the carrier fluid.
  • the charge director is acidic and reacts with the base- modified colorant particle to positively charge the particle. Again, the charging of the particle is accomplished via an acid-base reaction between the charge director and the base-modified particle surface.
  • the charge director may be selected from small molecules or polymers that are capable of forming reverse micelles in the non-polar carrier fluid. Such charge directors are generally colorless and tend to be dispersible or soluble in the carrier fluid.
  • the charge director is selected from a neutral and non-dissociable monomer or polymer such as, e.g., a polyisobuty- lene succinimide amine, which has a molecular structure as follows:
  • n is selected from a whole number ranging from 15 to 100.
  • charge director includes an ionizable molecule that is capable of disassociating to form charges.
  • charge directors include sodium di-2-ethylhexylsulfosuccinate and dioctyl sulfosuccinate.
  • the molecular structure of dioctyl sulfosuccinate is as follows:
  • charge director includes a zwitterion charge director such as, e.g., lecithin.
  • a zwitterion charge director such as, e.g., lecithin.
  • the molecular structure of lecithin is as shown as follo
  • the pigment particles are selected from organic or inorganic pigments, and have an average particle size ranging from about 1 nm to about 10 pm. In some examples, the average particle size ranges from about 10 nm to about 1 ⁇ . In other examples, the average particle size ranges from about 30 to 500 nm.
  • Such organic or inorganic pigment particles may be selected from black pigment particles, yellow pigment particles, magenta pigment particles, red pigment particles, violet pigments, cyan pigment particles, blue pigment par- tides, green pigment particles, orange pigment particles, brown pigment particles, and white pigment particles.
  • the organic or inorganic pigment particles may include spot-color pigment particles, which are formed from a combination of a predefined ratio of two or more primary color pigment particles.
  • carbon black pigments include those manu- factured by Mitsubishi Chemical Corporation, Japan (such as, e.g., carbon black No. 2300, No. 900, MCF88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, and No.
  • RAVEN® series manufactured by Columbian Chemicals Company, Marietta, Georgia, (such as, e.g., RAVEN® 5750, RAVEN® 5250, RAVEN® 5000, RAVEN® 3500, RAVEN® 1255, and RAVEN® 700); various carbon black pigments of the REGAL® series, the MOGUL® series, or the MONARCH® series manufactured by Cabot Corporation, Boston, Massachusetts, (such as, e.g., REGAL® 400R, REGAL® 330R, REGAL® 660R, MOGUL® L, MONARCH® 700, MONARCH ® 800, MONARCH® 880, MONARCH® 900, MONARCH ® 1000, MONARCH® 1100, MONARCH® 1300, and MONARCH® 1400); and various black pigments manufactured by Evonik Degussa Corporation, Parsippany, New Jersey, (such as, e.
  • inorganic pigments include metal oxides and ceramics, such as the oxides of titanium, silicon, iron, zinc, cobalt, manganese, nickel.
  • suitable inorganic pigments include those from the Shephord Color Company (Cinicinnati, OH) such as Black 10C909A, Black 10P922, Black 1G, Black 20F944, Black 30C933, Black 30C940, Black 30C965, Black 376A, Black 40P925, Black 411 A, Black 430, Black 444, Blue 10F545, Blue 10G51 1 , Blue 10G551 , Blue 10K525, Blue 10K579, Blue 21 1 , Blue 212, Blue 214, Blue 30C527, Blue 30C588, Blue 30C591 , Blue 385, Blue 40P585, Blue 424, Brown 10C873, Brown 10P835, Brown 10P850, Brown 10P857, Brown 157, Brown 20C819, Green 10K637, Green 187 B, Green 223,
  • Non-limiting examples of suitable yellow pigments include C.I. Pigment Yellow 1 , C.I. Pigment Yellow 2, C.I. Pigment Yellow 3, C.I. Pigment Yellow 4, C.I. Pigment Yellow 5, C.I. Pigment Yellow 6, C.I. Pigment Yellow 7, C.I. Pigment Yellow 10, C.I. Pigment Yellow 11 , C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, C.I. Pigment Yellow 16, C.I. Pigment Yellow 17, C.I. Pigment Yellow 24, C.I. Pigment Yellow 34, C.I. Pigment Yellow 35, C.I. Pigment Yellow 37, C.I. Pigment Yellow 53, C.I. Pigment Yellow 55, C.I.
  • Non-limiting examples of suitable magenta or red or violet organic pigments include C.I. Pigment Red 1 , C.I. Pigment Red 2, C.I. Pigment Red 3, C.I. Pigment Red 4, C.I. Pigment Red 5, C.I. Pigment Red 6, C.I. Pigment Red 7, C.I. Pigment Red 8, C.I. Pigment Red 9, C.I. Pigment Red 10, C.I. Pigment Red 11 , C.I. Pigment Red 12, C.I. Pigment Red 14, C.I. Pigment Red 15, C.I. Pigment Red 16, C.I. Pigment Red 17, C.I. Pigment Red 18, C.I. Pigment Red 19, C.I. Pigment Red 21 , C.I. Pigment Red 22, C.I.
  • Pigment Red 23 C.I. Pig- ment Red 30, C.I. Pigment Red 31 , C.I. Pigment Red 32, C.I. Pigment Red 37, C.I. Pigment Red 38, C.I. Pigment Red 40, C.I. Pigment Red 41 , C.I. Pigment Red 42, C.I. Pigment Red 48(Ca), C.I. Pigment Red 48(Mn), C.I. Pigment Red 57(Ca), C.I. Pigment Red 57:1, C.I. Pigment Red 88, C.I. Pigment Red 112, C.I. Pigment Red 114, C.I. Pigment Red 122, C.I. Pigment Red 123, C.I. Pigment Red 144, C.I.
  • Non-limiting examples of blue or cyan organic pigments include C.I. Pigment Blue 1 , C.I. Pigment Blue 2, C.I. Pigment Blue 3, C.I. Pigment Blue 15, C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:34, C.I. Pigment Blue 15:4, C.I. Pigment Blue 16, C.I. Pigment Blue 18, C.I. Pigment Blue 22, C.I. Pigment Blue 25, C.I. Pigment Blue 60, C.I. Pigment Blue 65, C.I. Pigment Blue 66, C.I. Vat Blue 4, and C.I. Vat Blue 60.
  • Non-limiting examples of green organic pigments include C.I. Pigment Green 1 , C.I. Pigment Green2, C.I. Pigment Green, 4, C.I. Pigment Green 7, C.I. Pigment Green 8, C.I. Pigment Green 10, C.I. Pigment Green 36, and C.I. Pigment Green 45.
  • Non-limiting examples of brown organic pigments include C.I.
  • Pigment Brown 1 C.I. Pigment Brown 5, C.I. Pigment Brown 22, C.I. Pigment Brown 23, C.I. Pigment Brown 25, and C.I. Pigment Brown , C.I. Pigment Brown 41 , and C.I. Pigment Brown 42.
  • Non-limiting examples of orange organic pigments include C.I. Pigment Orange 1 , C.I. Pigment Orange 2, C.I. Pigment Orange 5, C.I. Pigment
  • the herein-disclosed methods of grafting particles with novel functionalized tri-block copolymers and their dispersion in non-polar solvents results in minimal need for additional surfactants or charge directors.
  • This invention discloses methods of grafting particles with novel functional copolymers containing dispersants and their dispersion in non-polar solvents with minimal need for additional surfactants or surfactants.
  • the current invention uses a step-wise process to graft functional copolymers consecutively onto the particle/polymer surface. Each portion of these functional copolymers can be designed to optimize its intended function in the system based on the specific particle chemistry, solvent choice, and system requirement.
  • one portion can be designed to provide the best compatibility to the particle surface chemistry while exhibiting adequate solubility in the non-polar solvent.
  • the other portion can be designed to achieve the appropriate charge functionality in combination with the particle chemistry and other additives.
  • the known dispersant portion will provide steric stabilization to prevent agglomeration based on sys- tern requirements.
  • the methods use a step-wise process to graft three different chemically-functionalized polymers consecutively onto the particle/polymer surface.
  • Each block of these functionalized tri-block copolymers can be designed to optimize its intended function in the system based on the specific particle chemistry, solvent choice, and system requirement.
  • the inner block can be designed to provide the best compatibility to the particle surface chemistry while exhibiting adequate solubility in the non-polar solvent.
  • the middle block can be designed to achieve the appropriate charge functionality in combination with the particle chemistry and other additives.
  • At least one of the inner block, the outer block, or both may contain the dispersant moiety to assist in dispersing the pigment particles in non-polar solvents.
  • the outer block 5 can be designed to provide adequate steric stabilization to prevent agglomeration based on system requirements. For example, the outer block could be different for the same particle species in a single species ink compared to a dual species/charge system.
  • the electronic inks based on such pigment/colorant particles con- i o taining covalently attached dispersants are very stable, since both the charge- producing and steric stabilization groups are covalently bonded to the pigment surface. This approach contributes to the robustness of the imaging fluid. Because there is minimal need to add additional surfactants to stabilize the ink, the final electronic ink will have low background charge, and as a result will exhibit 15 less field screening effects and improve life time.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Inks, Pencil-Leads, Or Crayons (AREA)
  • Pigments, Carbon Blacks, Or Wood Stains (AREA)

Abstract

L'invention concerne des encres comprenant des particules de colorant ayant des dispersants attachés de façon covalente. Les encres comprennent un fluide support non polaire et des particules de pigment dispersées dans le fluide support non polaire. Les particules de pigment ont des greffons de copolymère à blocs, chaque greffon de copolymère à blocs comprenant un copolymère à blocs ayant deux ou trois blocs : un premier bloc fixé à la particule de pigment, un deuxième bloc fixé au premier bloc et un troisième bloc facultatif fixé au deuxième bloc, l'un des blocs contenant l'un ou l'autre parmi un dispersant et un groupe de solubilisation et stériquement encombré, ou les deux, un autre des blocs contenant des groupes latéraux fonctionnalisés soit acides soit basiques qui facilitent la charge de la particule de pigment, et le bloc facultatif contenant l'un ou l'autre parmi un dispersant et un groupe de solubilisation et encombré stériquement, ou les deux, avec la condition que le dispersant est présent sur au moins l'un des blocs.
PCT/US2012/043778 2012-06-22 2012-06-22 Encres comprenant des particules de colorant ayant des dispersants attachés de façon covalente WO2013191707A1 (fr)

Priority Applications (2)

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PCT/US2012/043778 WO2013191707A1 (fr) 2012-06-22 2012-06-22 Encres comprenant des particules de colorant ayant des dispersants attachés de façon covalente
TW102116665A TW201402720A (zh) 2012-06-22 2013-05-10 包括具有共價鍵結分散劑之著色劑粒子的墨水

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104559444A (zh) * 2014-12-15 2015-04-29 红安华源包装股份有限公司 一种印刷用仿金色油墨配方及其制备方法
CN104559440A (zh) * 2014-12-15 2015-04-29 红安华源包装股份有限公司 一种印刷用偏蓝色油墨配方及其制备方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040122160A1 (en) * 2002-12-16 2004-06-24 Piro Bonnie D. Pigment dispersions for solventborne coatings with improved rheology
US20060160950A1 (en) * 2001-11-29 2006-07-20 Clemens Auschra Pigment compositions with modified ATRP copolymer dispersants
US20110261435A1 (en) * 2008-12-30 2011-10-27 Yaron Grinwald Electronic inks and displays and image displaying methods
US20120081778A1 (en) * 2010-10-05 2012-04-05 Qin Liu Pigment-based ink
US20120105938A1 (en) * 2010-11-02 2012-05-03 Qin Liu Pigment-based inks

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060160950A1 (en) * 2001-11-29 2006-07-20 Clemens Auschra Pigment compositions with modified ATRP copolymer dispersants
US20040122160A1 (en) * 2002-12-16 2004-06-24 Piro Bonnie D. Pigment dispersions for solventborne coatings with improved rheology
US20110261435A1 (en) * 2008-12-30 2011-10-27 Yaron Grinwald Electronic inks and displays and image displaying methods
US20120081778A1 (en) * 2010-10-05 2012-04-05 Qin Liu Pigment-based ink
US20120105938A1 (en) * 2010-11-02 2012-05-03 Qin Liu Pigment-based inks

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104559444A (zh) * 2014-12-15 2015-04-29 红安华源包装股份有限公司 一种印刷用仿金色油墨配方及其制备方法
CN104559440A (zh) * 2014-12-15 2015-04-29 红安华源包装股份有限公司 一种印刷用偏蓝色油墨配方及其制备方法

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