EP3426736A1 - Encre electrophoretique - Google Patents
Encre electrophoretiqueInfo
- Publication number
- EP3426736A1 EP3426736A1 EP17713727.0A EP17713727A EP3426736A1 EP 3426736 A1 EP3426736 A1 EP 3426736A1 EP 17713727 A EP17713727 A EP 17713727A EP 3426736 A1 EP3426736 A1 EP 3426736A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- particles
- charge
- ink according
- electrophoretic
- ink
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
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- 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
- C09D11/52—Electrically conductive inks
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- 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
-
- 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
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/12—Developers with toner particles in liquid developer mixtures
- G03G9/125—Developers with toner particles in liquid developer mixtures characterised by the liquid
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/12—Developers with toner particles in liquid developer mixtures
- G03G9/135—Developers with toner particles in liquid developer mixtures characterised by stabiliser or charge-controlling agents
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/12—Developers with toner particles in liquid developer mixtures
- G03G9/135—Developers with toner particles in liquid developer mixtures characterised by stabiliser or charge-controlling agents
- G03G9/1355—Ionic, organic compounds
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
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- 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
- the present invention relates to the field of inks for electrophoretic display devices, and more particularly to an ink comprising colored particles dispersed in an apolar solvent and negatively charged.
- the invention relates to an electrophoretic ink, a method of manufacturing such an ink and a display device using such an ink.
- LCD liquid crystal display
- plasma plasma type
- paper printing the electronic displays are a great advantage because they are able to quickly update information displayed and therefore to change content, it is also said that they are rewritable.
- This type of display is however complex to achieve since its manufacture requires clean room work and advanced electronics. It is therefore relatively expensive. Displays made by print on paper, meanwhile, can be mass produced because very inexpensive, but do not re-register information over the old. This type of display is part of non-rewritable displays.
- This type of display is based on the EPIDS (ElectroPhoretic Image DisplayS) technology.
- EPIDS ElectroPhoretic Image DisplayS
- This technology consists of dispersing charged particles in a nonconductive medium between two parallel electrodes. More specifically, the display comprises a conductive surface electrode, a cavity comprising pixels filled with electrophoretic ink, and a bottom electrode connected to transistors for controlling each pixel.
- the pixels can be made in different ways. They can for example be made by means of a grid which compartmentalizes the cavity in as many pixels as necessary for the display, or they can be in the form of microcapsules, each microcapsule defining a pixel and being filled with said ink .
- the electrophoretic ink comprises negatively and / or positively charged colored particles dispersed in an apolar solvent.
- Negatively charged particles have a different color than positively charged particles.
- the negatively charged particles of each pixel will migrate to the positively charged electrode and vice versa.
- the positively charged particles are placed on one end of the pixel and the negatively charged particles on the other end, revealing the color of one or the other of the particles according to their position relative to the surface of the display. Therefore, by placing millions of pixels in the display cavity and controlling them by electric fields, by means of an electronic circuit for managing the display of information, a two-color image can be generated.
- One of the advantages of this type of display is that the contrast obtained depends directly on the migration of the particles and the color thereof.
- the display obtained is bistable since the image remains in place even after the electric field is cut.
- charge controllers are used which are further noted as CCA in the rest of the description.
- the charge controllers generally used are ionic or nonionic surfactants which allow to charge positively or negatively particles in an apolar medium, depending on the surface of these particles, that is to say according to their hydrophilic or hydrophobic nature and their acidic or basic property.
- US 2003/0137717 discloses an electrophoretic display of the prior art, comprising non-spherical capsules disposed in a layer on a substrate, each capsule comprising mobile electrophoretic particles suspended in a fluid and a charge controller.
- nonionic surfactants used as charge controllers mention may be made more particularly of the polyisobutylene succimide family, which has the trade name "OLOA”, or the family of sorbitan esters, which has the trade name “Span”. ". OLOAs are known to be basic CCAs that will induce negative charges on particles. Conversely, Span are known to be acidic CCAs that induce positive charges on the surface of particles.
- aerosol OT sodium dioctyl sulfosuccinate
- AOT aluminum oxide
- zirconyl 2-ethylhexanoate and hexadecyltrimethylammonium bromide (CTAB).
- CTAB hexadecyltrimethylammonium bromide
- Tina Lin et al in the article entitled "Transport of colloidal in a nonpolar solvent” published in the journal of the Royal Society of Chemistry, 2013, vol.9, pages 5173-5177, have thus highlighted that in the As apolar solvents, the AOT surfactants stabilize the charges through the creation of reverse micelles, which allow the dissociation of charge on the surface of the particles, and to have suspensions stabilizing the charge of the particles.
- the presence of inverse micelles has a significant effect on the mobility of particles: in a constant field, the particles begin to move, then slow exponentially, and eventually stop. This phenomenon is explained by the accumulation of reverse micelles in the medium, which clog the applied electric field, resulting in a reduction of the internal electric field.
- the electrophoretic displays then have a very limited life. [012]
- the applicant has therefore sought a solution to facilitate the loading of the particles in apolar medium, so that it can be precisely controlled and without creating reverse micelles. For this, the Applicant has been particularly interested in how to control the negative charge of a particle.
- the invention therefore aims to remedy at least one of the disadvantages of the prior art.
- the invention aims in particular to provide an electrophoretic ink comprising particles dispersed in an apolar solvent and a charge controller capable of charging these particles negatively, without inducing the appearance of inverse micelles capable of degrading the mobility of the particles.
- the invention also aims to provide a method of manufacturing such an electrophoretic ink, which is easy and quick to implement and allows precise control of the particle charge without inducing the formation of reverse micelles.
- the invention aims to provide an electrophoretic display device comprising such an ink, which has a significantly longer life compared to existing devices.
- the subject of the invention is an electrophoretic ink comprising particles that can be negatively charged, dispersed in an apolar organic solvent, said ink being characterized in that it comprises a charge controller of the trialkyl amine type, chosen from the following charge controllers: tributylamine, triisobutylamine, tripentylamine, trihexylamine, tri (2-ethylhexylamine), trioctylamine, triisooctylamine, tridodecylamine, triisododecylamine, and the particles have a hydrophobic surface and an isoelectric point (PIE) or point of zero load (PZC) lower than the pKa of the charge controller.
- PIE isoelectric point
- PZC point of zero load
- the used trialkyl amine charge controller which is a strong base, makes it possible to add more negative charges on the surface of the particles than the charge controllers used until now.
- the electrophoretic mobility of the particles thus charged is better than with the usual charge controllers, and does not decrease with time because no reverse micelle is formed in the apolar medium.
- the charge controller is preferably tridodecylamine
- the particles are modified pigments or hybrid particles comprising a modified pigment and a surface polymer;
- the hybrid particles are more particularly particles comprising a modified pigment core on the surface of which polymer particles have precipitated;
- the pigments are modified by silanization with coupling agents chosen from: methyltrimethoxysilane, ethylmethoxysilane,
- butyltrimethoxysilane hexyltrimethoxysilane, octylt methoxysilane (OTS), decyltrimethoxysilane, dodecyltrimethoxysilane (DTS), hexadecyltrimethoxy silane, or octadecyltrimethoxysilane, and preferably OTS or DTS;
- the grafting density of the alkyl chains resulting from the coupling agents on the surface of the pigments is between 3 and 6 mol / m 2 ; the degree of grafting of the alkyl chains resulting from the coupling agents on the surface of the pigments is between 35% and 75%, preferably between 50 and 70%,
- the pigments are previously covered with a silica envelope, before being modified by silanization;
- the apolar solvent is chosen from at least one of the following solvents: hydrocarbon oils, halocarbon oils, or silicone oils;
- the invention also relates to a method of manufacturing such an electrophoretic ink, characterized in that it comprises the following steps: synthesis of particles with a hydrophobic surface whose isoelectric point (PIE) or point of zero charge (PZC) is lower than the pKa of the charge controller, dispersion of the particles synthesized in an apolar solvent, addition of the charge controller in the apolar medium for charging said hydrophobic particles negatively, said charge controller being of the trialkyl amine type and selected from the following charge controllers: tributylamine, triisobutylamine, tripentylamine, trihexylamine, tri (2-ethylhexylamine), trioctylamine, triisooctylamine, tridodecylamine, triisododecylamine.
- PIE isoelectric point
- PZC point of zero charge
- the invention also relates to an electrophoretic display device comprising a plurality of cells filled with electrophoretic ink, each cell being in fluid communication with its neighbor and defining a pixel, a surface electrode and a bottom electrode. comprising a contact pad under each pixel, each pad being connected to a transistor of an integrated circuit for controlling the application of an electrostatic force to each pixel, said display being characterized in that the electrophoretic ink is consistent with that described above.
- the invention relates to the use of such an ink for producing such an electrophoretic display device.
- FIG. 2 a curve of the electrophoretic mobility of a modified hydrophobic pigment of TiO 2 @ SiO 2 -OTS as a function of the concentration of tridodecylamine in the apolar solvent
- FIG. 3 a curve of the electrophoretic mobility of a modified Fe2O3-OTS hydrophobic pigment as a function of the concentration of tridodecylamine in the apolar solvent
- FIG. 4 a curve of the electrophoretic mobility of a hydrophobic hybrid particle, comprising at the core, a modified Fe 2 O 3 -OTS pigment, and at the surface of poly (4-vinyl pyridine-lauryl acrylate) polymer particles; , depending on the concentration of tridodecylamine in the apolar solvent
- Figure 5 a plot of the surface tension of a drop of deionized water in Isopar-G measured at different concentrations of tridodecylamine in the medium to determine the critical micellar CMC concentration of tridodecylamine in the apolar medium.
- PZC zero point of charge
- PIE isoelectric point
- IEP also characterizes the acidic or basic property of a particle. The difference between the PZC and the PIE is based on the specific adsorption phenomenon. Thus, if the measured quantity does not depend on the solution used to measure it (pH, concentration, nature of the ions), then we are dealing with a PZC. Otherwise, it is a PIE that is measured.
- PIE or PZC of the particles it is measured in water by varying the pH of the solution, using a Malvern Nano ZS cell. More specifically, at each pH of the solution, the electrophoretic mobility of the particles is measured.
- the PIE, or the PZC corresponds to the pH at which the electrophoretic mobility of the particles is zero.
- colloidal system having a continuous liquid phase and a second discontinuous phase which is distributed throughout the continuous phase.
- the formulation of the electrophoretic ink according to the invention advantageously comprises chargeable particles, dispersed in an apolar organic solvent, and a charge controller of the trialkyl amino type, chosen from the controllers of the following feedstocks: tributylamine, triisobutylamine, tripentylamine, trihexylamine, th (2-ethylhexylamine), trioctylamine, triisooctylamine, tridodecylamine, triisododecylamine.
- this charge controller is a trialkyl amine with carbon chains whose carbon number is greater than 8.
- the charge controller is tridodecylamine, also denoted DodsN in the following description.
- the chargeable particles are particles having a PIE or PZC lower than the pKa of the charge controller used and having a hydrophobic surface.
- Tridodecylamine is a strong organic base, whose pKa is equal to 10.83. This amine reacts, by acid-base reaction with hydroxyl groups present on the surface of the particles. Ion pairs are formed on one side with a metal alkoxide for example, if the particle is a metal oxide, and a counter cation ammonium on the other, soluble in the apolar solvent. In apolar medium, the dissociated charges bring greater electrostatic forces than in the polar medium. It suffices then that a tiny part of these pairs of ions dissociates in the apolar medium to allow to induce negative charges on the surface of the particles and thus make them electrophoretic.
- the concentration of tridodecylamine in the apolar solvent is between 0.1 and 250 mmol / l, preferably between 0.5 and 150 mmol / l, and more preferably between 1 and 100 mmol / l.
- the particles that can be negatively charged are acidic or basic particles, which have a PIE isoelectric point or zero point of charge PZC less than the pKa (of 10.8) of tridodecylamine, and have a hydrophobic surface. They have a size between 250nm and 2 ⁇ . They are selected from any colored particle which has hydroxyl groups on its surface and is more acidic than tridodecylamine.
- the particles may be chosen from inorganic particles, for example modified inorganic pigments or from hybrid particles comprising a modified inorganic pigment in the core and surface polymer particles.
- the inorganic pigments may for example be selected from metal oxides.
- the inorganic pigments do not have sufficient acidity, it is possible to regulate the acid-base interactions on the surface of the pigments by covering them with a silica shell, resulting in obtaining pigments of the "core” type. shell ", or heart-bark, stable in apolar organic medium and with acidic properties.
- the inorganic pigments When the inorganic pigments have a weakly hydrophobic or hydrophilic surface, they can advantageously be modified, by silanization, in order to make their surface hydrophobic.
- coupling agents chosen from methyltrimethoxysilane, ethyltrimethoxysilane, butyltrimethoxysilane, hexyltrimethoxysilane, octyltethoxysilane (OTS), decyltrimethoxysilane, dodecyltrimethoxysilane (DTS), hexadecyltrimethoxysilane or octadecylt methoxysilane are grafted on the surface of the particles.
- the coupling agents are octyltrimethoxysilane (OTS) or dodecyltrimethoxysilane (DTS).
- OTS octyltrimethoxysilane
- DTS dodecyltrimethoxysilane
- the degree of grafting is determined from the elemental analysis of carbon on the unmodified inorganic pigment and on that silanized by coupling agents. OTS or DTS. More particularly, the degree of grafting N is determined from the following formula:
- C (%) is the carbon content of the modified pigment determined by the elemental carbon analysis
- S pa rt is the area of the modified pigment (m 2 ), determined from the diameter of the pigment by microscopy electronic
- m pa rt (g) is the mass of the particle, determined from the density and size of the pigment.
- N c is the number of carbon atoms constituting the OTS or DTS groups.
- the diameter of the hydrophilic pigment is considered identical to that of the modified pigment. Indeed, the groups OTS and DTS are supposed not to affect the diameter of the pigment because their size (of 10 ⁇ ), negligible compared to particle diameters ranging from 1 to 210 nm depending on their nature.
- the graft density of the alkyl chains from the OTS and DTS groups on the surface of the pigments has been determined and is between 3 and 6 mol / m 2 .
- the number of hydroxyl groups in the initial state, on the surface of the unmodified pigments is 8 mol / m 2 , as described in the article entitled "Encapsulation of Inorganic Particles" by Dispersion Polymerization in Polar Media: 1.
- the size of the pigments before and after modification was also measured by the dynamic light scattering technique (still noted DLS for "Dynamic Light Scattering"). Before modification, the pigments are hydrophilic and aggregated. After modification, the pigments become hydrophobic and their size is of the order of one micrometer.
- the surface modification of the pigments by OTS or DTS groups thus improves the dispersion of the particles in the apolar medium.
- the addition of tridodecylamine makes it possible, by electrostatic repulsion, to further reduce the particle size between 300 and 600 nm, thus improving the dispersion of the particles in the medium.
- This polymer surface is synthesized from functional monomers which may be chosen from 4-vinyl pyridine or acrylic acid, or methacrylic acid and its derivatives, copolymerized or otherwise, with another neutral monomer such as styrene or MMA (methacrylate). methyl) for example.
- functional monomers which may be chosen from 4-vinyl pyridine or acrylic acid, or methacrylic acid and its derivatives, copolymerized or otherwise, with another neutral monomer such as styrene or MMA (methacrylate). methyl
- the apolar solvent is advantageously chosen from liquid alkanes, liquid haloalkanes or liquid silicones. More particularly, it is chosen from halocarbon oils, hydrocarbon oils or silicone oils.
- hydrocarbon oils there may be mentioned for example paraffin oils, heptane, dodecane, tetradecane, etc.
- silicone oils mention may be made, for example, of the liquid silicone oils marketed by Dow Corning under the reference DOW 200, or else octamethylcyclosiloxane, poly (methylphenylsiloxane), hexamethyldisiloxane or polydimethylsiloxane. .
- the apolar solvent is selected from hydrocarbon oils, and preferably from paraffin oils. More preferably, the apolar solvent is chosen from paraffin oils manufactured and marketed by Exxon under the Isopar trade reference, and more particularly the oil marketed under the Isopar G reference.
- Example 1 Synthesis of color particles capable of being negatively charged a) Modified inorganic pigments [047] Different particles have been synthesized to be compared to each other.
- the inorganic pigments used are metal oxides, more particularly di2 titanium dioxide and Fe2O3 ferric oxide.
- the PIE isoelectric points of these two unmodified pigments were measured at 7.6 and 8.4, respectively, reflecting their basic character.
- the isoelectric point of the unmodified pigments was measured in water by varying the pH of the solution with a Malvern Nano ZS cell. More specifically, at each pH, the electrophoretic mobility of the particles was measured.
- the PIE corresponds to the pH where the electrophoretic mobility of the particles is zero.
- pigments being pigments hydrophilic surface
- they were modified by silanization carried out with octyltrimethoxysilane (OTS) or dodecyltrimethoxysilane (DTS).
- OTS octyltrimethoxysilane
- DTS dodecyltrimethoxysilane
- the hydrophilic pigment is mixed with toluene, at a rate of 50 g / l and 3.86 mmol of OTS (0.907 mg), or 3.06 mmol of DTS (0.89 mg), and then refluxed for 15 h.
- the pigments are then washed by centrifugation / redispersion cycles in toluene and then oven dried at 50 ° C. under vacuum.
- Another silanization method may be to make this modification by mass by introducing the pigment directly into a solution of OTS or DTS (at a rate of 50 g / l).
- the grafting rate is of the same order of magnitude.
- the grafting density of the alkyl groups derived from the coupling agents at the surface of the inorganic particles was determined from the elemental analysis of the carbon on the unmodified and modified pigments, and as described above. The higher the graft density, the more the particle has a hydrophobic surface.
- the particles thus modified are denoted T1O2-OTS, T1O2-DTS, Fe 2 O 3 -OTS or Fe 2 O 3 -DTS or else TiO 2 @SiO 2 -OTS and TiO 2 @SiO 2 -DTS when they are previously covered with a silica shell.
- the graft density of the alkyl chains from the OTS and DTS groups, on the surface of the pigments is between 3 and 6 mol / m 2 .
- Such a density corresponds to a level of between 35% and 75%, preferably between 50% and 70%.
- the surface of the pigments is then rendered hydrophobic, and the higher the degree of grafting, the more hydrophobicity is also.
- hydroxyl groups remain available on the surface of the pigments to allow the acid-base reaction with the DodsN and thus allow the negative loading of the pigments.
- a first step consists in synthesizing a macro-initiator.
- This macro-initiator will allow not only the polymerization of the polymer particles around the pigment, but also the stabilization of the particles in the apolar organic medium and the control of their sizes so that they are all homogeneous.
- a macro-initiator is an additive composed of a hydrophobic polymer chain, used for the stabilization of the particles, and an initiator part which serves to start the polymerization reaction and finally leads to the formation of a copolymer.
- the macro-initiator is advantageously synthesized by radical polymerization controlled by nitroxides with an initiator manufactured and marketed by Arkema under the trademark "Blocbuilder ®". After the initiation of the polymerization reaction on the macro-initiator, an amphiphilic copolymer is formed with a hydrophobic block (stabilizer) and a hydrophilic block which, by its precipitation, will be at the origin of nuclei. The latter then, during synthesis, coalesce and form particles. Thus, the hydrophobic polymer chains of the macro-initiator remain attached to the particles and can thus stabilize them in the apolar organic medium.
- the macro-initiator is used, poly (lauryl acrylate), synthesized by radical polymerization controlled by nitroxides, with an initiator manufactured and marketed by Arkema. under the brand name 'Blocbuilder ®', in toluene.
- the macro-initiator is synthesized and purified, it is mixed in the apolar solvent, for example Isopar-G, with a hydrophilic monomer, chosen for example from 4-vinyl pyridine, acrylic acid, or methacrylate. methyl, for example, and the modified pigment, so as to synthesize the hybrid particles comprising a modified pigment core on the surface of which polymer particles have precipitated.
- modified pigment Fe 2 O 3 OTS
- macro-initiator poly (lauryl acrylate)
- Isopar-G 3 g of modified pigment
- the macro-initiator then helps stabilize the pigment particles in the apolar solvent.
- This solution is mixed in an ultrasonic bath and then mixed using an ultrasound probe. It is then poured into a reactor with mechanical stirring. 10 g of functional monomers of 4-vinyl pyridine are then added, as well as 1.5 g of macro-initiator to initiate the reaction.
- the solution is then degassed with nitrogen for 1 hour, then heated at 120 ° C., with mechanical stirring at 300 rpm, for 15 hours.
- the particles obtained from (Fe2O3-OTS / Poly (4-VP-co-LA) are washed by centrifugation and redispersion in Isopar-G.
- the electrophoretic mobility of the electrophoretic particles of the inks thus synthesized is measured by the technique of analysis of the phase of the scattered light, again noted PALS (acronym for "Phase Analysis Light Scattering"), using a nano cell ZS from Malvern designed for apolar environment. A square signal ranging from 2.5 to 20 kV / m is applied to the cell. This technique consists in measuring the phase shift between the incident wave and the reflected wave by a moving electrophoretic particle in dispersion.
- the ink samples analyzed comprise 0.005% by weight of particles in the isopar G.
- tridodecylamine Since tridodecylamine is a strong base, with a pKa equal to 10.83, it brings more negative charges on the surface of the particles than the charge controllers. known OLOA for example. Thus, the electrophoretic mobility of the particles charged with tridodecylamine is higher (in absolute value) than those charged with OLOA 1 1000, Span 80 and ⁇ .
- the hydrophilic pigment particles represented by solid symbols, have a low electrophoretic mobility, and at most of the order of 0.075 mcmA / s in absolute value.
- the hydrophobic modified pigments represented in open symbols in FIG. 1, and negatively charged with DodsN (at a concentration of 16 mmol / l in Isopar G), exhibit a higher electrophoretic mobility, typically between 0.27 and 0. , 10 pmcm / Vs in absolute value.
- each hydrophobic particle was also measured as a function of the concentration of tridodecylamine in the apolar solvent.
- Figure 2 thus shows the electrophoretic mobility curve of the modified pigment TiO2 @ SiO2-OTS, as a function of the concentration of DodsN in Isopar-G. It turns out that the mobility of this pigment is maximum, in absolute value, with a concentration of DodsN in Isopar-G of 16 mmol / l. In this case, the maximum mobility is equal to -0.38 mcmA / s.
- FIG. 3 represents the electrophoretic mobility curve of the modified pigment Fe2O3-OTS, as a function of the concentration of DodsN in Isopar-G. It turns out that the mobility of this pigment is maximal, in absolute value, with a concentration of DodsN in Isopar-G of 16 mmol / l. In this case, the maximum mobility is equal to -0.33 mcmA / s.
- FIG. 4 represents the electrophoretic mobility curve of a Fe2O3-OTS hybrid particle with poly (4-vinylpyridine-co-laurylacrylate) polymer particles at the surface, as a function of the concentration of DodsN in the Isopar-G.
- the mobility of this pigment is maximum, in absolute value, with a concentration of DodsN in Isopar-G of 32 mmol / l. In this case, the maximum mobility is equal to -0.1 1 mcm / Vs.
- Tridodecylamine thus makes it possible to negatively charge particles, whose isoelectric point (PIE) or point of zero charge (PZC) is lower than the pKa of tridodecylamine and whose surface is hydrophobic, and to obtain electrophoretic particles having better electrophoretic mobility than with conventional charge controllers. Since the concentration of tridodecylamine in the ink is lower than the critical micelle concentration CMC, which has been determined at 250 mmol / l, the electrophoretic ink obtained has no reverse micelle capable of degrade the mobility of particles over time. Display devices comprising such an ink therefore have a significantly increased life.
- PIE isoelectric point
- PZC point of zero charge
- the determination of the CMC was carried out by measuring the surface tension of a drop of deionized water, in Isopar-G, by the hanging drop method, at different concentrations of tridodecylamine in the apolar medium, using a Kruss FM3200 blood pressure monitor. Each surface voltage value plotted on the curve of Figure 5 corresponds to an average of five measurements.
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- Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
- Inks, Pencil-Leads, Or Crayons (AREA)
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Application Number | Priority Date | Filing Date | Title |
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FR1652080A FR3048701B1 (fr) | 2016-03-11 | 2016-03-11 | Encre electrophoretique |
PCT/FR2017/050481 WO2017153666A1 (fr) | 2016-03-11 | 2017-03-03 | Encre electrophoretique |
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EP3426736A1 true EP3426736A1 (fr) | 2019-01-16 |
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EP17713727.0A Withdrawn EP3426736A1 (fr) | 2016-03-11 | 2017-03-03 | Encre electrophoretique |
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US (1) | US20200301304A1 (fr) |
EP (1) | EP3426736A1 (fr) |
JP (1) | JP2019512720A (fr) |
FR (1) | FR3048701B1 (fr) |
TW (1) | TWI644996B (fr) |
WO (1) | WO2017153666A1 (fr) |
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CN112852186B (zh) * | 2021-01-03 | 2024-04-02 | 安徽申兰华色材股份有限公司 | 一种亲水性可调酞菁蓝颜料的制备方法 |
CN114236936A (zh) * | 2021-12-22 | 2022-03-25 | 中山大学 | 一种应用于显示器件的导电油墨及其制备方法、显示器件 |
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US6839158B2 (en) | 1997-08-28 | 2005-01-04 | E Ink Corporation | Encapsulated electrophoretic displays having a monolayer of capsules and materials and methods for making the same |
EP1669798A4 (fr) * | 2003-09-03 | 2008-07-09 | Mitsubishi Pencil Co | Liquide destine a l'affichage electrophoretique, support d'affichage et affichage utilisant un tel liquide |
JP2012173602A (ja) * | 2011-02-23 | 2012-09-10 | Sony Corp | 電気泳動素子および表示装置 |
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2016
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- 2017-03-03 WO PCT/FR2017/050481 patent/WO2017153666A1/fr active Application Filing
- 2017-03-03 JP JP2018544925A patent/JP2019512720A/ja active Pending
- 2017-03-03 US US16/084,077 patent/US20200301304A1/en not_active Abandoned
- 2017-03-03 EP EP17713727.0A patent/EP3426736A1/fr not_active Withdrawn
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JP2019512720A (ja) | 2019-05-16 |
FR3048701B1 (fr) | 2020-06-26 |
WO2017153666A1 (fr) | 2017-09-14 |
FR3048701A1 (fr) | 2017-09-15 |
TWI644996B (zh) | 2018-12-21 |
TW201809165A (zh) | 2018-03-16 |
US20200301304A1 (en) | 2020-09-24 |
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