CN111378355A - Modified polyurethane emulsion, preparation method, electrophoretic coating liquid and electrophoretic display module - Google Patents

Modified polyurethane emulsion, preparation method, electrophoretic coating liquid and electrophoretic display module Download PDF

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CN111378355A
CN111378355A CN202010216890.5A CN202010216890A CN111378355A CN 111378355 A CN111378355 A CN 111378355A CN 202010216890 A CN202010216890 A CN 202010216890A CN 111378355 A CN111378355 A CN 111378355A
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polyurethane emulsion
modified polyurethane
soluble polymer
electrophoretic
electrophoretic display
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罗裕杰
盘婷
黄金浪
曾晞
陈宇
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Guangzhou Aoyi Materials And Devices Research Institute Co ltd
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Guangzhou Aoyi Materials And Devices Research Institute Co ltd
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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
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
    • C09D5/4419—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications with polymers obtained otherwise than by polymerisation reactions only involving carbon-to-carbon unsaturated bonds
    • C09D5/4465—Polyurethanes
    • 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
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
    • C09D5/4419—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications with polymers obtained otherwise than by polymerisation reactions only involving carbon-to-carbon unsaturated bonds
    • C09D5/443—Polyepoxides
    • C09D5/4457—Polyepoxides containing special additives, e.g. pigments, polymeric particles
    • 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
    • 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

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  • Life Sciences & Earth Sciences (AREA)
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Abstract

The invention provides a modified polyurethane emulsion, a preparation method thereof, an electrophoretic coating liquid and an electrophoretic display module. The modified polyurethane emulsion provided by the invention comprises aqueous polyurethane and nonionic water-soluble polymer, wherein the weight ratio of the aqueous polyurethane to the nonionic water-soluble polymer is 5-30:1, and the molecular chain terminal of the aqueous polyurethane contains-NH 2 and/or-OH. The polyurethane emulsion, the preparation method, the electrophoretic coating liquid and the electrophoretic display module provided by the invention can realize better water resistance.

Description

Modified polyurethane emulsion, preparation method, electrophoretic coating liquid and electrophoretic display module
Technical Field
The invention belongs to aqueous polyurethane emulsion and application thereof in the technical field of electrophoretic display, and particularly relates to modified polyurethane emulsion, a preparation method, an electrophoretic coating liquid and an electrophoretic display module.
Background
Electrophoretic image display (EPID) utilizes the phenomenon that colloidal dispersed particles undergo migration under the action of an electric field, and has advantages of high contrast, large viewing angle, high display brightness, low price, and easy realization of large-plane display. The disadvantage is that the reliability is poor, the threshold characteristic is not easy to control, and especially the agglomeration, precipitation, etc. of the particles in the dispersion are easy to occur, so that the lifetime of EPID display is short. Japanese patent JP2551783 discloses an electrophoretic display device in which the concept of electronic ink (encapsulated electrophoretic ink), namely microencapsulated electrophoretic display technology, is proposed. By utilizing the electrophoretic display principle, the pigment particles and the dark dye solution are innovatively wrapped in the microcapsule, and electrophoretic display is realized in the microcapsule, so that the defects of agglomeration, deposition and the like of the electrophoretic particles in the range larger than the capsule size are overcome, the stability of the microcapsule is improved, and the service life of the microcapsule is prolonged. The electronic ink is an ink-shaped suspended matter, can realize reversible, bistable and flexible display under the action of an external electric field, is a flexible display material and technology which are integrated with subjects of physics, chemistry, electronics and the like, has the advantages of good visibility, low power consumption, strong information loading capacity, convenience in carrying, low manufacturing cost, no electromagnetic radiation and the like, and can fundamentally solve the defects of the existing flat panel display technology.
The current electronic ink adopts spherical transparent smooth microcapsules of 30-300 microns to coat a dielectric suspension, electrophoretic particles are floated in the suspension, the microcapsules are distributed in an adhesive to form an electrophoretic coating liquid, an electrophoretic display layer is formed after the display coating liquid is coated and cured, and the electrophoretic display layer is positioned between an ITO (indium tin oxide) conductive film and a driving backboard. Due to the coating requirement of the electrophoretic coating liquid, various aqueous auxiliary agents such as an anionic thickener and the like are inevitably used, and the original adhesive has strong water solubility, so that the dried electrophoretic display layer has poor water resistance and is greatly influenced by the environmental humidity, and thus, the electrical property is unstable, and the optimal photoelectric effect cannot be achieved. However, in the process of preparing and coating the electrophoretic coating liquid, the adhesive needs a certain amount of hydrophilic ionic groups to ensure the dispersion of the electrophoretic coating liquid and the normal coating appearance.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a modified polyurethane emulsion which can realize better water resistance, a preparation method thereof, an electrophoretic coating liquid and an electrophoretic display module.
The invention provides a modified polyurethane emulsion, which comprises aqueous polyurethane and a nonionic water-soluble polymer, wherein the weight ratio of the aqueous polyurethane to the nonionic water-soluble polymer is 5-30:1, and the molecular chain terminal of the aqueous polyurethane contains-NH 2 and/or-OH.
Preferably, the polyurethane resin further comprises a thermal crosslinking auxiliary agent, wherein the thermal crosslinking auxiliary agent comprises one or more of polyaldehyde, polyglycidyl ether and water-soluble polyisocyanate.
Preferably, the molecular chain terminal of the waterborne polyurethane contains-NH 2 and-OH, and the molar ratio of the-OH to the-NH 2 is (0.1-5): 1.
Preferably, the molecular weight of the nonionic water-soluble polymer is 5 to 15 ten thousand.
Preferably, the ratio of the mole number of the anions of the waterborne polyurethane to the total mass of the feeding solid parts is less than 1: 1400.
Preferably, the nonionic water-soluble polymer comprises one or more of hydroxyethyl cellulose, hydroxyl propyl cellulose and hydroxypropyl methyl cellulose.
Preferably, the molar mass ratio of the-NH 2 and/or-OH to the nonionic water-soluble polymer is (0.1-1): 1.
The invention also provides a preparation method of the modified polyurethane emulsion, which comprises the following steps:
(1) according to the parts by weight, 10-30 parts of diisocyanate, 20-45 parts of polyester diol and 15-35 parts of polyether diol are reacted for 3-7 hours at the temperature of 60-100 ℃;
(2) when the content of NCO% is measured to be below 3.5%, 3-10 parts of chain extender I are added, and the reaction is carried out for 1-4 hours at the temperature of 60-100 ℃;
(3) when the content of NCO% is measured to be below 2.5%, 3-10 parts of a second chain extender are added to react for 0.1-2 hours to obtain the waterborne polyurethane;
(4) mixing the aqueous polyurethane with a nonionic water-soluble polymer.
The invention also provides an electrophoretic coating liquid which comprises an adhesive and microcapsules dispersed in the adhesive, wherein the adhesive comprises the modified polyurethane emulsion, and the microcapsules contain suspension and charged pigment particles dispersed in the suspension.
The invention also provides an electrophoretic display module which comprises an electrophoretic display layer and a conductive layer, wherein the electrophoretic display layer is formed by coating the electrophoretic coating liquid on the conductive layer.
The modified polyurethane emulsion, the preparation method, the electrophoretic coating liquid and the electrophoretic display module provided by the invention have better water resistance.
Drawings
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings. The same reference numerals are used throughout the drawings to denote the same parts, and the drawings are not necessarily drawn to scale in actual dimensions, with emphasis instead being placed upon illustrating the principles of the invention:
fig. 1 is a schematic structural diagram of an electrophoretic display provided in this embodiment.
Detailed Description
The technical solutions of the present invention are further described in detail with reference to specific examples so that those skilled in the art can better understand the present invention and can implement the present invention, but the examples are not intended to limit the present invention.
Referring to fig. 1, an embodiment of the present invention provides a modified polyurethane emulsion, including aqueous polyurethane and a nonionic water-soluble polymer, where a weight ratio of the aqueous polyurethane to the nonionic water-soluble polymer is 5-30: 1. The weight ratio of the aqueous polyurethane to the nonionic water-soluble polymer is preferably 10-20: 1. The molecular chain terminal of the aqueous polyurethane contains-NH 2 and/or-OH. The modified polyurethane emulsion in the embodiment can have better water resistance after being cured into a film, and can also ensure better coating performance. The molecular chain end of the aqueous polyurethane of this embodiment contains-NH 2 (amino group) or-OH (hydroxyl group). When the modified polyurethane emulsion is used, in the process of drying and film forming, the waterborne polyurethane can be combined with the nonionic water-soluble polymer to form a film, so that the aim of improving the water resistance is fulfilled, and meanwhile, the modified polyurethane emulsion can have anions, so that the modified polyurethane emulsion can have better coating performance when being used. The modified polyurethane emulsion of the embodiment is preferably applied to an electrophoretic coating liquid, and is used as a glue for dispersing microcapsules in the electrophoretic coating liquid, but can be used as other glues.
The embodiment also provides an electrophoretic coating liquid, which comprises an adhesive and microcapsules dispersed in the adhesive, wherein the adhesive comprises a modified polyurethane emulsion, and the microcapsules contain a suspension and charged pigment particles dispersed in the suspension. The electrophoretic display layer is formed after the electrophoretic coating liquid provided by the embodiment is coated and cured, and the electrophoretic coating liquid is embedded into the non-ionic high polymer with high molecular weight in the waterborne polyurethane, so that the sensitivity of the electrophoretic display layer to water vapor after the electrophoretic coating liquid is dried is reduced, and the service life of the display device is prolonged. The electrophoretic display layer formed by coating and curing the electrophoretic coating liquid of the embodiment has not only good water resistance, but also high white reflectance.
The microcapsules used in this example were prepared using a preparation method of the prior art. Regarding the microcapsule preparation technology in the electrophoretic display technology, a large number of documents and patents are reported at home and abroad at present. At present, chemical methods, physicochemical methods and mechanical methods are used for preparing microcapsules, wherein the chemical methods include coacervation, interfacial polymerization, in-situ polymerization, and the like. Nakamura et al describe a gelatin-gum arabic system for preparing microcapsules for electrophoretic display technology by complex coacervation (literature source: Eiji Nakamura, et al, Proceedings of SIDI' 98International Symposium, May 1998, p1014-1017), which has good solvent stability, but the long-term use of gelatin and gum arabic both affect the properties of the microcapsules because they are natural polymers and have poor stability. US patent application US 6262833 discloses a method for preparing microcapsules by in situ polymerization using urea formaldehyde resin to encapsulate electrophoretic fluid.
The embodiment of the invention also provides an electrophoretic display module which comprises an electrophoretic display layer and a conductive layer, wherein the electrophoretic display layer is formed by coating the electrophoretic coating liquid on the conductive layer. The conductive layer may be a conductive thin film ITO or a driving backplane TFT. The electrophoretic coating liquid provided by the embodiment reduces the sensitivity of the electrophoretic display layer to water vapor after drying. The electrophoretic display module provided by the embodiment also has better white reflectivity.
Referring to fig. 1, the present invention further provides an electrophoretic display, which includes a first conductive layer 1, a second conductive layer 3, and an electrophoretic display layer 2 disposed between the first conductive layer and the second conductive layer 1, 3, where the first conductive layer 1 and the second conductive layer 3 are used to apply an electrical signal across the electrophoretic display layer 2, so that electrophoretic particles in microcapsules of the electrophoretic display layer 2 move, and a display effect of the electrophoretic display is achieved. In this embodiment, the electrophoretic coating liquid may be coated on the first conductive layer 1 or the second conductive layer 3 to form an electrophoretic display module. For example, the electrophoretic display coating liquid is coated on the first conductive layer 1 to form an electrophoretic display module, and then the second conductive layer 3 is bonded with the electrophoretic display module through the bonding layer 4, wherein the first conductive layer 1 is a conductive thin film ITO, and the second conductive layer 3 is a driving back plate TFT. The electrophoretic display layer 2 includes an adhesive 51 having a modified polyurethane emulsion and microcapsules 52 dispersed in the adhesive.
The electrophoretic display provided by the embodiment has better water resistance and higher white reflectivity.
In a preferred embodiment, the modified polyurethane emulsion further comprises a thermal crosslinking assistant, wherein the thermal crosslinking assistant comprises one or more of polyaldehyde, polyglycidyl ether and water-soluble polyisocyanate. Under the action of the thermal crosslinking assistant, the mixed material of the water-based polyurethane and the nonionic water-soluble polymer consumes-C00H, -OH, -NH2 and-NH-in the mixed material in the process of curing and film-forming, so that hydrophilic groups are further reduced, and the water resistance of the modified polyurethane emulsion after curing is better improved. In the present embodiment, the polyaldehyde means a substance having 2 or more aldehyde functional groups, for example, glyoxal, glutaraldehyde, or the like.
In a further preferred embodiment, the amount of the thermal crosslinking assistant is 0.01-1% of the total amount of the modified polyurethane emulsion. Can be 0.01% -0.1%, 0.1% -1% or 0.05% -0.2%.
In a preferred embodiment, the mass ratio of-NH 2 and/or-OH to the nonionic water-soluble polymer is (0.1-1): 1. When the molecular chain end of the aqueous polyurethane contains-NH 2 and does not contain-OH, -NH2 and the mass ratio of the nonionic water-soluble polymer is (0.1-1): 1. When the molecular chain end of the aqueous polyurethane contains-OH and does not contain-NH 2, the mass ratio of-OH to the nonionic water-soluble polymer is (0.1-1): 1. When the molecular chain terminal of the aqueous polyurethane contains-NH 2 and-OH at the same time, the mass ratio of the sum of the mole numbers of-NH 2 and-OH to the nonionic water-soluble polymer is (0.1-1): 1.
The modified polyurethane emulsion can ensure that the waterborne polyurethane has better crosslinking reaction in the film forming process with the nonionic water-soluble polymer, ensures that the waterborne polyurethane is embedded with a proper amount of the nonionic water-soluble polymer in the middle year, realizes that the modified polyurethane emulsion can ensure better coating performance when in use, and simultaneously can ensure better water resistance after being cured.
In a preferred embodiment, the molecular chain end of the aqueous polyurethane contains-NH 2 and-OH, -OH and-NH 2 in a molar ratio of (0.1-5): 1. The molecular chain terminal of the waterborne polyurethane of the embodiment contains-NH 2, which can accelerate the crosslinking reaction at the later reaction stage in the film forming process of the waterborne polyurethane and the nonionic water-soluble polymer, and better improve the water resistance of the cured modified polyurethane emulsion, but more-NH 2 can make the cured modified polyurethane emulsion yellow, and too fast more-NH 2 crosslinking and curing speed can affect the coating performance, so that the proper proportion of-NH 2 and-OH should be ensured.
In a preferred embodiment, the molecular weight of the nonionic water-soluble polymer is 5 to 15 ten thousand. The molecular weight of the nonionic water-soluble polymer is limited within a reasonable range, so that the nonionic water-soluble polymer can have a good thickening effect, the appearance of the modified polyurethane emulsion after curing can be maintained, and the modified polyurethane emulsion has good performance. In a more preferred embodiment, the molecular weight of the nonionic water-soluble polymer is 7 to 12 ten thousand.
In a preferred embodiment, the molecular weight of the aqueous polyurethane is from 3 to 8 million. The proper molecular weight can ensure that the nonionic water-soluble polymer and the waterborne polyurethane have better crosslinking effect in the film forming process. The higher molecular weight of the waterborne polyurethane can cause poor water solubility and affect the coating effect of the modified polyurethane emulsion, and the higher molecular weight can cause poor compatibility of the waterborne polyurethane and the nonionic water-soluble polymer, so that the terminal of the waterborne polyurethane contains enough mol numbers of-NH 2 and-OH which are not beneficial to the crosslinking reaction of the waterborne polyurethane and the nonionic water-soluble polymer during the post-curing of the film forming. The smaller molecular weight of the waterborne polyurethane can cause the poor mechanical property of the film layer of the cured modified polyurethane emulsion. Therefore, the molecular weight of the aqueous polyurethane is limited.
In a preferred embodiment, the ratio of the number of moles of anions of the aqueous polyurethane to the total mass of the charge solids is less than 1: 1400. The total mass of the solid parts of the materials fed in the embodiment refers to the mass of the non-volatile matters left in the materials without solvent and water in the process of preparing the waterborne polyurethane.
The anion mole number of the waterborne polyurethane is lower than that of polyurethane in the prior art, so that the modified polyurethane emulsion has better water resistance after being cured, and simultaneously, the microcapsule can be better dispersed in the modified polyurethane emulsion and better coating performance by matching with reasonable and nonionic water-soluble polymers.
In a preferred embodiment, the non-ionic water soluble polymer comprises one or more of hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose. The water-based polyurethane thickening agent has a good thickening effect, has good compatibility with water-based polyurethane, and is favorable for carrying out good crosslinking reaction with-NH 2 and/or-OH of the water-based polyurethane during film forming and curing.
In a preferred embodiment, the preparation raw materials of the waterborne polyurethane comprise isocyanate, polyester and polyether, and the molar ratio of the polyether to the polyester is 1 (1-5). In a preferred embodiment, the polyether is a polyether diol and the polyester is a polyester diol. The appropriate polyether content proportion can ensure a certain hydrophilic chain segment and a certain water solubility, so that the quantity of anions is reduced, and the modified polyurethane emulsion has better water resistance after being cured.
The embodiment of the invention also provides a preparation method of the waterborne polyurethane, which comprises the following steps:
(1) according to the weight portion, 10-3 portions of diisocyanate, 20-45 portions of polyester diol and 15-35 portions of polyether diol are reacted for 3-7 hours at the temperature of 60-100 ℃. This step is a bulk prepolymer reaction.
(2) When the content of NCO% is measured to be below 2.5%, and when the content of NCO% is measured to be below 3.5%, 3-10 parts of chain extender I are added, and the reaction is carried out for 1-4 hours at the temperature of 60-100 ℃. This step is a secondary chain extension.
(3) And when the content of NCO% is measured to be below 2.5%, 3-10 parts of a second chain extender are added, and the reaction is carried out for 0.1-2 hours to obtain the waterborne polyurethane. This step is a triple chain extension, before which the-OH content is controlled according to the determined NCO% content and the corresponding chain extender content. Control of the moles and molar ratio of-OH and-NH 2 was achieved by three chain extensions.
The embodiment of the invention also provides a preparation method of the modified polyurethane emulsion, which comprises the following steps:
(1) according to the parts by weight, 10-30 parts of diisocyanate, 20-45 parts of polyester diol and 15-35 parts of polyether diol are reacted for 3-7 hours at the temperature of 60-100 ℃;
(2) when the content of NCO% is measured to be below 3.5%, 3-10 parts of chain extender I are added, and the reaction is carried out for 1-4 hours at the temperature of 60-100 ℃;
(3) when the content of NCO% is measured to be below 2.5%, adding acetone, reducing the temperature to be below 40-70 ℃, stirring until the mixture is completely dissolved, reducing the temperature to be below 20-45 ℃, adding 3-10 parts of a second chain extender, reacting for 0.1-2 hours, adding a salt forming agent, and finally removing the acetone in vacuum to obtain the waterborne polyurethane;
(4) mixing the water-based polyurethane with the nonionic water-soluble polymer.
The chain extender one and the chain extender two referred to in this embodiment may be the same or different. In a preferred embodiment, the chain extender one is a small molecule diol or a diol containing hydrophilic groups, such as one or more of DMPA (2, 2-dimethylolpropionic acid), DMBA (dimethylolbutanoic acid), ethylene glycol, monoethylene glycol, butanediol, hexanediol, neopentyl glycol, TMP (trimethylolpropane), or mixtures thereof. The chain extender II can be one or a mixture of more of ethanolamine, diethanolamine, triethanolamine, ethylenediamine, sodium diaminobenzene sulfonate, sodium ethylenediamine ethanesulfonate, IPDA (isophorone diamine) and polyether amine D-230.
In a preferred embodiment, the polyester diol may be polycaprolactone, polycarbonate, poly (glycol adipate), sulfonate polyester, carboxylate polyester, or a mixture of one or more thereof, and has a molecular weight of 300 to 3000.
In a preferred embodiment, the diisocyanate may be aliphatic or a mixture of aromatic and aliphatic, and may be one or more of IPDI (isophorone diisocyanate), HDI (hexamethylene diisocyanate), HMDI (dicyclohexylmethane-4, 4' -diisocyanate), XDI (xylylene diisocyanate), MDI (diphenylmethane diisocyanate), TDI (toluene diisocyanate), TMXDI (tetramethylm-xylylene diisocyanate), or a mixture thereof.
In a preferred embodiment, the polyether diol is a polyether diol with a molecular weight of 400-3000, and the polyether can be one or more of PPG (propylene oxide polyether diol) and PTMEG (polytetrahydrofuran ether) PEG (polyethylene glycol).
In a preferred embodiment, the salt forming agent can be one or a mixture of triethylamine and ammonia water.
The embodiment of the invention also provides a preparation method of the electrophoretic coating liquid, which is obtained by mixing the modified polyurethane emulsion and the microcapsule.
The technical scheme and the technical effect of the invention are further described in detail by combining the embodiment and the comparative example.
Example 1
Adding 25% of aliphatic diisocyanate (IPDI), 30% of polyester diol (polycaprolactone, molecular weight 1000), 10% of sulfonate polyester (molecular weight 2000) and 25% of polyether diol (PPG molecular weight 2000) into a reaction pot, stirring for 3 hours at 85 ℃, adding 6% of chain extender I (2% of ethylene glycol and 4% of DMBA) when the NCO% content is detected to be 3.5%, continuously stirring for 2 hours at 85 ℃, reducing the temperature to 50 ℃ when the NCO% content is detected to be 2.0%, and mixing according to the weight ratio of 1:1 (reaction mixture) is added with acetone, stirred until the mixture is completely dissolved, cooled to 30 ℃, 5 percent of chain extender II (IPDA) is dripped in, the temperature is kept constant for 0.5 hour, then pure water containing triethylamine is poured in, and the mixture is dispersed at high speed for 1 hour. And finally, performing vacuum de-acetone to obtain the waterborne polyurethane, wherein the molecular chain terminal of the waterborne polyurethane contains-NH 2 and/or-OH.
Uniformly mixing the waterborne polyurethane and the HPMC pre-dispersion liquid with the molecular weight of 10 ten thousand according to the solid mass ratio of 15:1 to obtain the modified polyurethane emulsion. Adding glutaraldehyde in 0.1 wt% of the coating liquid before coating, mixing the modified polyurethane emulsion with electrophoretic display microcapsule and final coating to obtain the film.
Comparative example 1
The preparation method comprises the following steps:
mixing the aqueous anionic polyurethane emulsion with the molecular weight of 6-12 ten thousand with electrophoresis microcapsules, adding 1% of anionic acrylic thickener to adjust the viscosity of the ink to the viscosity required by coating, and finally coating to obtain the membrane.
The films prepared in example 1 and comparative example 1 were subjected to relevant tests, and specific data are shown in table 1.
TABLE 1
Figure BDA0002424779590000081
Figure BDA0002424779590000091
The data in table 1 show that the film prepared in example 1 has good stability and high white reflectance.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of the equivalent structure L or equivalent flow path, or direct or indirect applications in other related fields, which are made by the present specification, are included in the scope of the present invention.

Claims (10)

1. The modified polyurethane emulsion is characterized by comprising aqueous polyurethane and a nonionic water-soluble polymer, wherein the weight ratio of the aqueous polyurethane to the nonionic water-soluble polymer is 5-30:1, and the molecular chain terminal of the aqueous polyurethane contains-NH 2 and/or-OH.
2. The modified polyurethane emulsion of claim 1, further comprising a thermal crosslinking aid comprising one or more of polyaldehydes, polyglycidyl ethers, and water-soluble polyisocyanates.
3. The modified polyurethane emulsion according to claim 1, wherein the molecular chain terminal of the aqueous polyurethane contains-NH 2 and-OH, and the molar ratio of-OH to-NH 2 is (0.1-5): 1.
4. The modified polyurethane emulsion according to claim 1, wherein the nonionic water-soluble polymer has a molecular weight of 5 to 15 ten thousand.
5. The modified polyurethane emulsion according to claim 1, wherein the ratio of the number of moles of the anion of the aqueous polyurethane to the total mass of the charged solids is less than 1: 1400.
6. The modified polyurethane emulsion of claim 1, wherein the non-ionic water soluble polymer comprises one or more of hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose.
7. The modified polyurethane emulsion according to claim 1, wherein the mass ratio of the-NH 2 and/or the-OH to the nonionic water-soluble polymer is (0.1-1): 1.
8. The process for producing a modified polyurethane emulsion according to any one of claims 1 to 7, which comprises the steps of:
(1) according to the parts by weight, 10-30 parts of diisocyanate, 20-45 parts of polyester diol and 15-35 parts of polyether diol are reacted for 3-7 hours at the temperature of 60-100 ℃;
(2) when the content of NCO% is measured to be below 3.5%, 3-10 parts of chain extender I are added, and the reaction is carried out for 1-4 hours at the temperature of 60-100 ℃;
(3) when the content of NCO% is measured to be below 2.5%, 3-10 parts of a second chain extender are added to react for 0.1-2 hours to obtain the waterborne polyurethane;
(4) mixing the aqueous polyurethane with a nonionic water-soluble polymer.
9. An electrophoretic coating liquid comprising a binder and microcapsules dispersed in the binder, wherein the binder comprises the modified polyurethane emulsion according to any one of claims 1 to 7, and the microcapsules contain a suspension and charged pigment particles dispersed in the suspension.
10. An electrophoretic display module comprising an electrophoretic display layer and a conductive layer, wherein the electrophoretic display layer is formed by applying the electrophoretic coating liquid according to claim 9 onto the conductive layer.
CN202010216890.5A 2020-03-25 2020-03-25 Modified polyurethane emulsion, preparation method, electrophoretic coating liquid and electrophoretic display module Pending CN111378355A (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105061716A (en) * 2015-07-22 2015-11-18 四川大学 Waterborne polyurethane emulsion and preparation method therefor
CN106867388A (en) * 2017-01-18 2017-06-20 华南理工大学 A kind of selfreparing anti-dazzle aqueous polyurethane coating and preparation method thereof

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105061716A (en) * 2015-07-22 2015-11-18 四川大学 Waterborne polyurethane emulsion and preparation method therefor
CN106867388A (en) * 2017-01-18 2017-06-20 华南理工大学 A kind of selfreparing anti-dazzle aqueous polyurethane coating and preparation method thereof

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