WO2013189151A1

WO2013189151A1 - Electronic ink and manufacturing method

Info

Publication number: WO2013189151A1
Application number: PCT/CN2012/084978
Authority: WO
Inventors: 王雪岚; 薛建设; 刘宸; 舒适
Original assignee: 京东方科技集团股份有限公司
Priority date: 2012-06-21
Filing date: 2012-11-21
Publication date: 2013-12-27
Also published as: CN102757681A

Abstract

An electronic ink and a manufacturing method thereof. The ink comprises an electrophoresis liquid, an oil soluble dye, and electrophoresis particles, wherein the electrophoresis particle comprises a zinc oxide microsphere and an ionized coating layer which covers the zinc oxide microsphere. The zinc oxide microsphere with the ionized coating layer is used as the electrophoresis particle, and the produced electronic ink has very good stability.

Description

Electronic ink and preparation method

The invention relates to an electronic ink and a preparation method. Background technique

At present, electronic paper preparation methods include spin ball technology, micro-adhesive technology, micro-film technology and electrowetting technology. Sipix uses a precision abrasive to press the micro-array array arranged on the plastic substrate. Each micro-cup is about 50-200μπι, and the suspension is filled in the micro-cup for electrophoretic display. US ΜΙΤ and E-ink use micro-adhesive technology to place industrial dark dye suspensions, charged light-colored particles and other materials in transparent micro-adhesives. At the end of 2003, Philips introduced electrowetting display technology to prepare electronic paper.

Micro-adhesive technology is a common display method for electronic paper research and commercial products (US US5961804 and US5930026), but there are still many technologies to be broken. For example, microcapsules are difficult to prepare uniformly, the particle size distribution is very wide, the mechanical properties are difficult to control, and the crucible wall is prone to aging and cracking, thereby causing problems such as low contrast of the display member and short life. In addition, the color-developing electrophoretic particles filled in the microcapsules have a wide size distribution and a shape that is not spherical, so that the surface charge distribution is irregular and easy to settle; and the movement of the non-spherical shape under the electric field is liable to cause bridging between the particles, affecting other The movement of the particles results in lower resolution.

The microcup is an electrophoresis micro-chamber made by lithography or micro-filming. Due to the controllable size and stable material properties, it effectively overcomes the shortcomings of micro-gels. Moreover, due to the limitation of the micro-chamber, the electrophoresis image It shows that the sensitivity to external disturbance is reduced, and it is easier to reach the bistable structure; the thickness of the microcup wall can also be adjusted to greatly improve the pressure resistance and scratch resistance. However, the above techniques are also extremely demanding for the electronic ink to be used, and the electronic ink is required to have high stability. Summary of the invention

The invention provides an electronic ink comprising an oil-soluble dye and an electrophoretic liquid containing electrophoretic particles, the electrophoretic particles comprising an oxidized microsphere and an ionized coating layer coated on the oxidized microsphere.

Preferably, the ionization coating layer is an ionized polyethylene wax. Preferably, the ionization coating layer comprises an ionized ring group.

Preferably, the ionized coating layer comprises ionized pyridinium.

Preferably, the ionization coating layer is ionized polyvinylpyrrolidone.

Preferably, the ionization coating layer is ionized polystyrene.

Preferably, the electrophoresis liquid is one or more selected from the group consisting of a liquid aliphatic hydrocarbon, a liquid alcohol having 7 or more carbon atoms, a liquid ester having 7 or more carbon atoms, and a liquid organic acid having 4 or more carbon atoms. .

In the present invention, the liquid aliphatic hydrocarbon or liquid! 3⁄4 generation hydrocarbon means an aliphatic hydrocarbon or a halogenated hydrocarbon which is liquid at a temperature ranging from 0 to 80 ° C, respectively. Liquid hydrocarbons generally have a carbon chain length of 6-20. Specific examples are hexane, cyclohexane, heptane, cycloheptane, octane, cyclooctane, decane, undecane, dodecane, tridecane. , tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, cyclohexene, 1 , , 3-cyclohexadiene, 1-heptyne, 1- Octyne or toluene, etc. liquid! Examples of 3⁄4 generation hydrocarbons are tetrachloroethylene, 1-chlorocyclohexane, bromopentane, 1-bromocyclohexane or tetrachloronaphthalene, and the like.

Preferably, the oil-soluble dye comprises oil-soluble blue, oil-soluble yellow, oil-soluble red, oil-soluble green or oil-soluble violet; and the oil-soluble dye has a mass percentage of 0.5-10%.

In the present invention, "the ionized coating layer contains an ionized ring group" means that an ionized ring group exists in the compound (or polymer) forming the coating layer. Similarly, "the ionized coating layer contains an ionized pyridine group" means that an ionized pyridyl group is present in the compound (or polymer) forming the coating layer.

The invention also provides a preparation method of electronic ink, comprising the following steps:

1) preparing a coating of oxidized microspheres with a uniform particle size;

2) adding the prepared oxidized microsphere suspension with a coating layer and a surface ionic agent for surface ionization of the oxidized layer with a coating layer into an organic solvent, and dispersing to form an electrophoretic liquid containing the electrophoretic particles. The electrophoretic particles in the electrophoresis liquid comprise an oxidized microsphere and an ionized coating layer coated on the oxidized core;

3) An oil-soluble dye is added to the electrophoresis liquid containing the electrophoretic particles, and the electronic ink is formed by ultrasonic vibration.

Preferably, the preparing the oxidized microsphere suspension with the coating layer comprises the following steps: S1) dispersing the oxidized nanospheres in a solvent to form a suspension;

S2) heating the suspension to 80~: 120 ° C, adding polyethylene wax to the suspension, stirring After mixing, the temperature was lowered to room temperature to obtain the coated oxidized microsphere suspension.

Preferably, the preparing the oxidized microsphere suspension with the coating layer comprises the following steps:

S I ) dispersing the oxidized nanospheres in a solvent to form a suspension;

S II ) adding an oxidizing agent solution in the presence of stirring and shielding gas, adding a mixed solution I and a reducing agent solution, and adjusting the pH range of 6.0 to 8.0 after completion of the reaction, thereby obtaining the coated oxidized microsphere suspension The mixed solution I is a mixture comprising diethyl phenyl benzoate and glycidyl methacrylate.

Preferably, the preparing the oxidized microsphere suspension with a coating layer comprises the following steps: K1) dispersing the oxidized nanospheres in a solvent to form a suspension;

K2) adding a oxidizing agent solution under stirring, introducing a shielding gas, adding a mixture of divinylbenzenepyridine and 4-vinylpyridine and a reducing agent solution to obtain the coated oxidized microsphere suspension .

Q1) dispersing the oxidized nanospheres in a solvent containing sodium hexametaphosphate to adjust a pH range of 6.0-8.0 to form a suspension;

Q2) Polyvinylpyrrolidone is added to the suspension, and the suspension of the polyvinylpyrrolidone added is ultrasonically dispersed to obtain the coated oxidized microsphere suspension.

Specifically, the preparing the oxidized microsphere suspension with a coating layer comprises the following steps: D1) dispersing the oxidized nanospheres in a mixed solvent composed of ethanol and water, and dispersing to form a suspension;

D2) A monomer styrene in which an initiator azodiethylbutyronitrile is dissolved is added dropwise to the suspension to react at 50 to 90 ° C to obtain the coating-containing oxidized microsphere suspension.

The electronic ink provided by the invention and the preparation method thereof use the oxidized microspheres with the ionized coating layer as the electrophoretic particles, and the formed electronic ink has good stability, and can satisfy the stability of the electronic ink of the micro cup electronic paper. Sexual requirements. DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly described below. It is obvious that the drawings in the following description relate only to some embodiments of the present invention, and are not intended to limit the present invention. . 1 is a schematic view of an electronic ink provided by the present invention;

Fig. 2 is a view showing a contrast test experimental apparatus in a microcup electrophoretic display experiment; Fig. 3 is a graph showing a driving voltage/contrast curve of the microcup electronic paper made of the electronic ink according to the first embodiment of the present invention. detailed description

The technical solutions of the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings of the embodiments of the present invention. It is apparent that the described embodiments are part of the embodiments of the invention, rather than all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the described embodiments of the present invention without departing from the scope of the invention are within the scope of the invention.

Determination of particle size of oxidized particles:

The particle size of the oxidized particles prepared in the present invention is measured by a laser light scattering particle size analyzer. That is, take appropriate amount of oxidized nanospheres, add ethylene glycol, ultrasonically disperse for 15 minutes, take l.lmL sample suspension in the sample cell, and measure the elastic collision rate between the laser and the sample to keep it at Ι χΙΟ ⁴ ~ 2.64 χ ^{10 6} times / s, then the sample size was automatically scanned to obtain the sample size, and a total of 10 batches of the sample suspension were prepared.

Electronic ink dispersion stability test:

透光 The 712 spectrophotometer was used to measure the change of the transmittance of the system with time. Based on this, the dispersion stability of nano-oxidized microspheres in electronic ink before and after modification was analyzed. The small light transmittance indicates that the solid-liquid interface formed by the particles and the liquid is stable, the particles are not easily agglomerated, and the powder is easily dispersed stably in the liquid; on the contrary, the large transmittance indicates that the solid-liquid interface tension is large, and the particles are easily agglomerated. Sink, the powder cannot form a stable system in the liquid. Weigh the same amount of modified oxidized microspheres before and after the modification and mix them with the electrophoresis medium, and let them stand for 90 days, extract the upper layer of turbid liquid, use the electrophoretic medium as the reference solution, and irradiate the turbid liquid with light with a wavelength of 580 nm. Record the light transmittance. Tested once a day in the first week and every 1 month in the future, for a total of 3 months.

The invention provides an electronic ink, as shown in FIG. 1, comprising an oil-soluble dye and an electrophoresis liquid 2 containing electrophoretic particles 1. The electrophoretic particles comprise an oxidized microsphere 12 and an ionized coating coated on the oxidized microsphere. Layer 11.

The electronic ink provided by the invention has good stability and can meet the micro-cup electronic paper pair electrophoresis Liquid requirements.

Specifically, the ionized coating layer coated on the oxidized microspheres is an ionized polyethylene wax.具体 The specific preparation method of using ionized polyethylene wax as ionization coating layer is as follows:

1) preparing a coating of oxidized microspheres with a uniform particle size;

2) adding the prepared oxidized microspheres with a coating layer and a surface ionic agent for surface ionization of the oxidized layer with a coating layer into an organic solvent, and dispersing to form an electrophoresis liquid containing the electrophoretic particles. The electrophoretic particles in the electrophoresis fluid include an oxidized microsphere and an ionized coating layer coated on the oxidized core;

Specifically, step 1) includes the following steps:

51) dispersing the oxidized nanospheres in a solvent to form a suspension;

52) The suspension was heated to 80 to 120 ° C, polyethylene wax was added to the suspension, and after stirring, the temperature was lowered to room temperature to obtain the coating-containing oxidized aqueous suspension.

In the step S2), the heating temperature is 80 120 ° C, preferably 80 ° C, 100 ° C, 120 ° C, and the following is specifically described by taking 120 ° C as an example. Example 1

1) Preparation of oxidized nanospheres First step: Prepare a solution of acetic acid in ethanol at a concentration of 0.25 mol/L; prepare a sodium hydroxide ethanol solution at a concentration of 5 mol/L; add 8 parts by weight of sodium hydroxide ethanol solution The reaction was carried out by stirring at 40 ° C for 50 minutes in 4 parts by weight of a solution of acetic acid in ethanol. After completion of the reaction, the mixture was filtered with a filter and washed. After drying at 80 ° C in vacuo, dispersed in 25 parts by weight of ethanol, the mixed solution is recorded as a ₃ , the solution concentration is 0.035 mol / L;

The second step: preparing a 0.5 mol/L acetic acid diethylene glycol solution, and preparing the oxidized microspheres by crystal growth. The solution of diethylene glycol diacetate is recorded as solution b ₃ , 2 parts by weight of solution a _{3 is} added to 100 parts by weight of solution b ₃ , stirred at 220 ° C for 3 hours, centrifuged at 1000 rpm, and the supernatant is removed. The liquid was washed and a monodisperse oxidized nanosphere having a particle diameter of 50 nm was obtained, and the particle size was measured by the above-described particle size test method. As a result, as shown in Table 1, the average deviation of the particle size distribution was less than 7%.

In the present invention, in order to facilitate the region, the oxidized nano-microspheres prepared by the embodiment are also referred to as 50. Nm oxidation of nanospheres. That is, the 50 nm level represented by 50 nm here is not strictly 50 nm. Table 1 Oxidation of nano-spheres particle size distribution table

2) Coating poly

The 50 nm oxidized nano-microspheres having very good monodispersity prepared by the above method were further modified as a core. Specific steps are as follows.

With 0.5 part by weight of tetrachloroethylene as a dispersing solvent, 0.05 parts by weight of 50 nm oxidized microspheres were slowly added under ultrasonic vibration. Ultrasonic vibration for 70 minutes, warming to 120 °C, slowly adding 0.005 parts by weight of polyethylene wax under ultrasonic vibration, and then continuing to vibrate for 90 minutes to fully diffuse, then cool down to obtain surface coated with polyethylene wax. Oxidation of the ball, that is, electrophoretic particles, complete the preparation of the oxidized function duplex ball. The above tetrachloroethylene suspension was diluted with 0.44 parts by weight of tetrachloroethylene, ultrasonically shaken for 80 minutes, and 0.02 parts by weight of BYK112 charge dispersant was slowly added in portions under ultrasonic vibration, and then 0.02 parts by weight of oil-soluble blue was added. The ultrasonic wave was shaken for 70 minutes to obtain electronic ink. After standing for 90 days, the upper layer of turbid liquid was taken, and the electronic ink bottom liquid was used as a reference solution, and the light transmittance was recorded. The results are shown in Table 2 below. Comparative example 1

An equivalent amount of 50 nm oxidized microspheres of Example 1 was weighed, and a tetrachloroethylene solution of the same concentration of 50 nm oxidized microspheres as in Example 1 was prepared using tetrachloroethylene as a solvent, and allowed to stand for 90 days, and the upper layer was turbid. Liquid, using tetrachloroethylene as a reference solution, record the light transmittance. The results are shown in Table 2 below. Table 2 particle size 50nm oxidation microsphere modification before and after electronic ink stability test

Time (day) Id 2d 3d 4d 5d 6d 7d 30d 60d 90d Unmodified light transmittance 8.1 48.2 76.7 87.6 87.5 87.7 87.9 87.8 87.7 87.6 Electronic ink transmittance 6.1 7.5 8.0 9.1 9.3 8.9 9.0 9.0 9.3 9.2 It can be seen from the table that the transmittance of the electronic ink prepared in this embodiment is substantially stable with time, indicating that the electronic ink is very stable.

3) Microcup electrophoresis display experiment

The electronic ink prepared in Example 1 was injected into a microcup and packaged into a microchamber. The driver circuit is attached to the packaged micro-chamber to complete the assembly of the entire principle device. Contrast Test Experimental Device As shown in Figure 2, the excitation pulse voltage is provided by the function generator/counter with adjustable frequency. When testing, select the drive voltage frequency to be 1 kHz. A krypton laser beam having a diameter of 0.8 mm passes vertically through the polarizing plate in the horizontal direction of the polarizing plate, and the light from the sample is restricted by the aperture having an aperture angle of 2.5 degrees, and is received by the silicon photodetector. The measured drive voltage / contrast curve is shown in Figure 3. Under the action of the electric field, when the driving voltage is higher than 4V, the contrast rises rapidly. When the driving voltage is 8V, the contrast ratio can reach 20:1, as shown in Figure 3.

The results of the above application experiments show that the electronic ink obtained by the method of the present invention is not only excellent in dispersibility but also excellent in various other properties, and can be effectively used as an electronic ink for electronic paper. Example 2

1) Preparation of oxidized nanospheres

Step 1: Prepare 0.002 mol/L tungstophosphoric acid ethanol solution; 0.015 mol/L triethanolamine aqueous solution; and 0.02 mol/L acetic acid aqueous solution;

The second step: separately measuring 60 parts by weight of the phosphonium phosphate solution, 60 parts by weight of the aqueous solution of acetic acid,

60 parts by weight of aqueous triethanolamine solution, the aqueous solution of acetic acid was slowly added dropwise to the solution of tungstophosphoric acid ethanol under stirring; after stirring for 30 minutes, the aqueous solution of triethanolamine was slowly added dropwise under stirring, and after the addition was completed, the temperature was raised to 80 ° C. After stirring for 3 hours, the mixture was centrifuged at 8000 rpm, the supernatant liquid was removed, and the underlying solid was washed by infrared vacuum drying to obtain monodisperse oxidized nanospheres having a particle diameter of 160 nm. The results are shown in Table 3. The deviation is less than 6%.

In the present invention, for the sake of easy distinction, the oxidized nano-microspheres prepared by this example are also referred to as 160 nm oxidized nanospheres. That is, the meaning of the 160 nm level represented by 160 nm here is not strictly 160 nm. Table 3 Oxidation of nano-spheres particle size distribution table

2) coated polyethylene wax

The monodispersity 160 nm oxidized nano-microspheres prepared by the above method were further modified as cores. Specific steps are as follows.

With 0.5 part by weight of tetrachloroethylene as a dispersion solvent, 0.1 part by weight of 160 nm oxidized microspheres was slowly added under ultrasonic vibration. After ultrasonic vibration for 90 minutes, the temperature was raised to 150 ° C, and a polyethylene wax having a relative solvent amount of 0.015 parts by weight was slowly added under ultrasonic vibration. After ultrasonic vibration for 180 minutes, the temperature was lowered to obtain an oxidized sphere of surface-coated polyethylene wax. That is, the electrophoretic particles complete the preparation of the oxidized functional double sphere. The above tetrachloroethylene suspension was diluted with 0.38 parts by weight of tetrachloroethylene, sonicated for 120 minutes, and 0.08 parts by weight of BYK 9076 charge dispersant was slowly added in portions under ultrasonic vibration, and then 0.1 part by weight of the mixture was slowly added in portions. The oil was red and the ultrasonic wave was shaken for 100 minutes to obtain an electronic ink. After standing for 90 days, the upper layer of the turbid liquid was taken, and the electronic ink bottom liquid was used as a reference solution to record the light transmittance. The results are shown in Table 4 below. Comparative example 2

An appropriate amount of 160 nm oxidized microspheres of Example 2 was weighed, and a tetrachloroethylene solution of the same concentration of 160 nm oxidized microspheres as in Example 2 was prepared using tetrachloroethylene as a solvent, and allowed to stand for 90 days, and the upper layer was turbid. Liquid, using tetrachloroethylene as a reference solution, record the light transmittance. The results are shown in Table 4 below. Table 4 particle size 160nm oxidation microspheres before and after electronic ink stability test

It can be seen from the table that the transmittance of the electronic ink prepared in this embodiment is substantially stable with time, indicating that the electronic ink is very stable. Preferably, the ionizing coating layer coated on the oxidized microspheres is a compound or polymer having an ionized ring group, that is, the coating layer contains an ionized epoxy group.

The specific preparation method of the ionized ring group as the ionization coating layer is as follows:

1) preparing a coating of oxidized microspheres with a uniform particle size;

Preferably, step 1) comprises the following steps:

S I ) dispersing the oxidized nanospheres in a solvent to form a suspension;

S II) adding an oxidizing agent solution in the presence of stirring and shielding gas, adding a mixed solution I and a reducing agent solution, and adjusting the pH range of 6.0 to 8.0 after completion of the reaction to obtain the coated oxidized aqueous suspension. The mixed solution I is a mixture comprising diethyl phenyl benzoate and glycidyl methacrylate. Example 3

1) Preparation of oxidized nanospheres

The first step: preparing a solution of 0.1 mol/L acetic acid in ethanol; preparing a sodium hydroxide ethanol solution having a concentration of 2 mol/L; adding 8 parts by weight of sodium hydroxide ethanol solution to 4 parts by weight of acetic acid in ethanol solution The reaction was carried out by stirring at 100 ° C for 45 minutes. After completion of the reaction, the mixture was filtered with a filter and washed. After drying at 80 ° C in vacuo, it was dispersed in 15 parts by weight of ethanol to obtain a ₂ with a solution concentration of 0.015 mol/L;

The second step: preparing a concentration of 0.25 mol / L of diethylene glycol diacetate solution; 釆 using crystal growth method to prepare oxidized microspheres. The diethylene glycol diacetate solution is recorded as the solution b ₂ , and 2 parts by weight of the solution a _{2 is} added to 500 parts by weight of the solution b ₂ , stirred at 200 ° C for 3 hours, and centrifuged at 8000 rpm to remove the supernatant. The liquid was washed and a monodisperse oxidized nanosphere having a particle diameter of 80 nm was obtained, and the particle size was measured by the above-described particle size test method. As a result, as shown in Table 5, the average deviation of the particle size distribution was less than 6%. The present invention in order to facilitate the oxidation zone by ^a further speech nanospheres prepared as in Example 80 nm is also referred to speech oxide nanospheres. That is, the 80 nm level represented by 80 nm here is not strictly 80 nm. Table 5 Oxidation of nano-spheres particle size distribution table

2) coating a layer containing an epoxy group

80 80nm oxidized nano-microspheres with very good monodispersity prepared by the above method. 40 parts by weight of oxidized words and 120 parts by weight of deionized water were mixed, and the mixture was dispersed in a ball mill for 4 hours; the dispersed emulsion was introduced into the reactor, and 0.3 parts by weight of ammonium persulfate was added while stirring. And an oxidizing agent solution prepared by using 40 parts by weight of deionized water; argon gas is used as a shielding gas, stirred at a maximum stirring rate of 800 rpm for 40 minutes at normal temperature, and then heated to 35 ° C in an argon atmosphere to continue stirring, alternately dropping a mixture of 0.4 parts by weight of divinylbenzene and 2.5 parts by weight of glycidyl methacrylate added with 1015 parts by weight of sodium hydrogen sulfite, 40 parts by weight of dodecyldidecylbenzyl group at a concentration of 1.5 CMC A reducing agent solution prepared with ammonium chloride; a dropping time of 3 hours. After the completion of the dropwise addition, the reaction was further stirred for 2 hours; finally, the pH of the system was adjusted to neutral with a 10 wt% aqueous solution of sodium hydrogencarbonate. Upon completion of the reaction, an oxidized nucleus-shell microsphere dispersion having a structure in which the inner layer is a white oxidized microsphere of a globular structure and an outer layer is an epoxy group.

The microspheres are then ionized. Specifically, in 120 parts of the oxidized nucleus-shell microsphere dispersion, 80 parts of a 12 wt% tridecylethylamine hydrochloride solution was added dropwise with stirring; after the dropwise addition was completed, the mixture was stirred at a maximum stirring rate of 800 rpm. After a minute, the temperature was slowly raised to 80 ° C, and stirring was continued for 5 hours. After cooling to normal temperature, the reaction was terminated, and the epoxy group on the surface of the microspheres was opened to form hydroxyl groups and hydrochloride ions, thereby realizing ionization on the surface of the microspheres. The water in the above solution was removed using a rotary evaporator and vacuum dried to obtain an ionized oxidized nucleus-shell microsphere, i.e., an electrophoretic microsphere.

Ten parts of the electrophoresis microspheres were added to 100 parts of tetradecane, and ultrasonically shaken for 150 minutes to be sufficiently dispersed to obtain an electronic ink. After standing for 90 days, the upper layer of turbid liquid was taken, and tetradecane was used as a reference solution, and the light transmittance was recorded. The results are shown in Table 6 below. Comparative example 3

The 80 nm oxidized nano-spheres with very good monodispersity prepared by the above preparation method of the oxidized nano-spheres of Example 3 were weighed and mixed with 100 parts of tetradecane, and ultrasonically shaken for 150 minutes, and left to stand. For 90 days, the upper layer of turbid liquid was taken, and tetradecane was used as a reference solution to record the light transmittance. The results are shown in Table 6 below.

Electron ink stability test before and after modification of 80nm oxidized microspheres

It can be seen from the above table that the transmittance of the oxidized suspension liquid before and after the modification varies greatly, indicating that the oxidation of the surface is achieved by the oxidation of the oxidized word, and the affinity of the two phases is obtained, and the dispersion stability is very good. Great improvement; In addition, the light transmittance is basically stable with time, indicating that the electronic ink system is very stable.

Preferably, the ionizing coating layer coated on the oxidized microspheres has a compound or polymer comprising ionized pyridinium, i.e., the coating layer comprises ionized pyridine groups.

The specific preparation method of using ionized pyrene as the ionization coating layer is as follows:

1) preparing a coating of oxidized microspheres with a uniform particle size;

Specifically, step 1) includes the following steps:

K1) dispersing the oxidized nanospheres in a solvent to form a suspension;

K2) Under stirring, an oxidizing agent solution is added, a shielding gas is introduced, and a mixture of divinylbenzenepyridine and 4-vinylpyridine and a reducing agent solution are added to obtain the oxide-containing suspension having a coating layer. Example 4

1) Preparation of oxidized nanospheres

The first step: separately preparing 0.002 mol/L tungstophosphoric acid ethanol solution; 0.025 mol/L triethanolamine aqueous solution; and 0.05 mol/L acetic acid aqueous solution;

60 parts by weight of aqueous solution of triethanolamine, the aqueous solution of acetic acid was slowly added dropwise to the solution of tungstophosphoric acid ethanol under stirring; after stirring for 60 minutes, the aqueous solution of triethanolamine was slowly added dropwise under stirring, and after the addition was completed, the temperature was raised to 120 ° C. After stirring for 4.5 hours, the mixture was centrifuged at 12,000 rpm, the supernatant liquid was removed, and the underlying solid was washed by infrared vacuum drying to obtain monodisperse oxidized nanospheres having a particle diameter of 100 nm. The results are shown in Table 7, and the average particle size distribution was as follows. The deviation is less than 5%.

In the present invention, for the sake of easy distinction, the oxidized nanospheres prepared by this example are also referred to as 100 nm oxidized nanospheres. That is, the 100 nm level represented by 100 nm here is not strictly 100 nm. Table 7 Oxidation of nano-spheres particle size distribution table

2) a coated layer containing a given pyrazol ^ ¹ group

l The monodisperse 100 nm oxidized nanospheres prepared by the above method are very good. 40 parts by weight of oxidized words and 120 parts by weight of deionized water were mixed, and the mixture was dispersed in a ball mill for 6 hours; the dispersed emulsion was introduced into the reactor, and 0.4 parts by weight of hydrogen peroxide was added while stirring. 50 parts by weight of oxidizing agent solution prepared by deionized water; argon gas is used as a shielding gas, stirred at a maximum stirring rate of 800 rpm at normal temperature for 60 minutes, and then heated to 60 ° C in an argon atmosphere to continue stirring, alternately dropping a mixture of 0.4 parts by weight of divinylbenzene and 2.0 parts by weight of 4-vinylpyridine and 0.025 parts by weight of sodium hydrogen hydride, 0.025 parts by weight of ferrous sulfate heptahydrate and 40 parts by weight of 5 CMC A reducing agent solution prepared from sodium dodecylbenzenesulfonate; the addition time is 3 hours. After the completion of the dropwise addition, the reaction was further stirred for 3 hours; finally, the pH of the system was adjusted to 7.0 with a 10 wt% aqueous sodium hydrogencarbonate solution. After the reaction is completed, an oxidized nucleus-shell microsphere dispersion is obtained, and the structure thereof is obtained. The inner layer is the global structure of the white oxidized microspheres, and the outer layer is the pyridine group.

The microspheres are then ionized. Specifically, in 120 parts by weight of the oxidized nucleus-shell microsphere dispersion, 40 parts by weight of a 14% by weight aqueous hydrochloric acid solution was added dropwise with stirring, and the mixture was stirred at a maximum stirring rate of 800 rpm for 40 minutes, and slowly heated to 100 ° C for 5 hours. After cooling to normal temperature, the reaction is terminated, and the pyridyl group on the surface of the microspheres is salted to form a pyridine hydrochloride to achieve ionization on the surface of the microsphere. The water in the above solution was removed using a rotary evaporator and vacuum dried to obtain an ionized oxidized nucleus-shell microsphere, i.e., an electrophoresis gleam.

10 parts by weight of the electrophoretic microspheres were added to 90 parts by weight of isoamyl heptanoate, and ultrasonically shaken for 100 minutes to sufficiently disperse, thereby obtaining an electronic ink. After standing for 90 days, the upper layer of turbid liquid was taken, and isoamyl heptanoate was used as a reference solution, and the light transmittance was recorded. The results are shown in Table 8 below.

Comparative example 4

Weigh an equal amount of the above-mentioned preparation method to prepare a very good monodisperse lOOnm oxidized nano-spheres mixed with 90 parts of isoamyl heptanoate, ultrasonically shake for 100 minutes, let stand for 90 days, extract the upper layer of turbid liquid, with heptanoic acid Isoamyl ester was used as a reference solution to record the light transmittance. The results are shown in Table 8 below. Table 8 particle size lOOnm oxidation microspheres before and after electronic ink stability test

Specifically, the ionized coating layer coated on the oxidized microspheres is ionized polyvinylpyrrolidone.

The specific preparation method of using ionized polyvinylpyrrolidone as the ionization coating layer is as follows: 1) preparing a coating layer of the oxidized microsphere suspension having a uniform particle diameter;

2) adding the prepared oxidized microspheres with a coating layer and a surface ionic agent for surface ionization of the oxidized layer with a coating layer into an organic solvent, and dispersing to form an electrophoresis liquid containing the electrophoretic particles. The electrophoretic particles in the electrophoresis fluid include an oxidized microsphere and a coating on the oxidized core Sub-coating layer;

Specifically, step 1) includes the following steps:

Q2) Polyvinylpyrrolidone is added to the suspension, and the suspension of the polyvinylpyrrolidone added is ultrasonically dispersed to obtain the oxide layer with the coating. Example 5

1) Preparation of oxidized nanospheres

The first step: preparing a solution of 0.01 mol/L acetic acid in ethanol; preparing a sodium hydroxide ethanol solution having a concentration of 0.5 mol/L; adding 8 parts by weight of sodium hydroxide ethanol solution to 4 parts by weight of acetic acid in ethanol solution The reaction was carried out by stirring at 80 ° C for 30 minutes. After completion of the reaction, the mixture was filtered with a filter and washed. After drying at 80 ° C in vacuo, it was dispersed in 10 parts by weight of ethanol to obtain a solution having a concentration of 0.003 mol/L.

The second step: preparing a concentration of 0.01 mol / L of diethylene glycol diacetate solution; 釆 using crystal growth method to prepare oxidized microspheres. Record the solution of diethylene glycol diacetate as a solution, add 2 parts by weight of the solution to 1000 parts by weight of the solution, stir at 180 ° C for 90 minutes, centrifuge at 5000 rpm, remove the supernatant and wash. Monodisperse oxidized nano-microspheres having a particle diameter of 120 nm were obtained, and the particle size was measured by the above-described particle size test method. As a result, as shown in Table 9, the average deviation of the particle size distribution was less than 7%.

In the present invention, for the sake of easy distinction, the oxidized nanospheres prepared by this example are also referred to as 120 nm oxidized nanospheres. That is, the 120 nm level represented by 120 nm here is not strictly 120 nm. Table 9 Oxidation of nano-spheres particle size distribution table

Batch 1 2 3 4 5 6 7 8 9 10 Particle size (nm) 120.11 113.38 116.25 125.37 119.45 121.19 126.98 118.95 116.68 127.86 Particle size deviation 0.09% 5.51% 3.12% 4.47% 0.45% 3.24% 5.82% 0.87% 2.76% 6.55% 2) coated polyvinylpyrrolidone

A certain amount of 120 nm oxidized nanospheres was dissolved in water containing a small amount of sodium hexametaphosphate, adjusted to pH 6 with 1% HCl, and fully dissolved by ultrasonic vibration. The modifier polyvinylpyrrolidone PVP K30 was added and ultrasonically dispersed for 1 h. The mixture was dried at 105 ° C for 24 h, and thoroughly sieved to obtain organically modified oxidized nanospheres. The organically modified oxidized nanospheres were used as chromogenic particles, and tetrachloroethylene was used as the dispersion medium. The organically modified oxidized nanospheres were 15% by weight, ultrasonically oscillated for 1 hour, and 2 wt% of oil-soluble red dye was added. 3 wt% byk 161 charge dispersant dispersant was added, and ultrasonic wave was shaken for 30 minutes to prepare an electrophoretic display liquid.

Comparative example 5

The equivalent amount of the oxidized nanospheres was weighed and the tetrachloroethylene solution of the same concentration of the oxidized nanospheres was prepared in the same manner as in the above examples, and ultrasonically shaken for 30 minutes, and left to stand at 90. Days, the upper layer of turbid liquid was taken, and tetrachloroethylene was used as a reference solution to record the light transmittance. The results are shown in Table 10 below. Table 10 Example 3: Oxidation of nano-microspheres before and after modification of electronic ink stability test

It can be seen from the table that the transmittance of the electronic ink prepared in this embodiment is substantially stable with time, indicating that the electronic ink is very stable.

Specifically, the ionized coating layer coated on the oxidized microspheres is ionized polystyrene. The specific preparation method of using ionized polystyrene as the ionization coating layer is as follows:

1) preparing a coating of oxidized microspheres with a uniform particle size;

3) adding an oil-soluble dye to the electrophoresis liquid containing the electrophoretic particles, and ultrasonically oscillating Into the electronic ink.

Specifically, step 1) includes the following steps:

D1) dispersing the oxidized nanospheres in a mixed solvent of ethanol and water, and dispersing to form a suspension;

D2) adding a monomer styrene in which an initiator azodiethylbutyronitrile is dissolved to the suspension

The reaction with 50-90 ° C gives the oxide word with the coating. Example 6

1) Preparation of oxidized nanospheres

(1) separately preparing a 0.001 mol/L solution of tungstophosphoric acid; 0.005 mol/L of a triethanolamine aqueous solution; and 0.01 mol/L of an aqueous solution of acetic acid;

(2) separately taking 60 parts by weight of a phosphonium phosphate solution, 60 parts by weight of an aqueous solution of acetic acid, 60 parts by weight of an aqueous solution of triethanolamine, and slowly adding the aqueous solution of acetic acid to the aqueous solution of the aqueous solution of ethanol in a stirred state; after stirring for 10 minutes The aqueous solution of triethanolamine was slowly added dropwise under stirring. After the dropwise addition was completed, the mixture was heated to 100 ° C and stirred for 2 hours. After centrifugation at 5000 rpm, the supernatant was removed and the underlying solid was washed by infrared vacuum drying to obtain a particle size of 200. The monodisperse oxidized nanospheres of nm showed the results as shown in Table 11, and the average deviation of the particle size distribution was less than 7%.

In the present invention, for the sake of easy distinction, the oxidized nanospheres prepared by this example are also referred to as 200 nm oxidized nanospheres. That is, the 200 nm level represented by 200 nm here is not strictly 200 nm. Table 11 Oxidation of nano-spheres particle size distribution table

The quantitative stabilizer hydroxypropylcellulose and 200 nm oxidized nanospheres were dissolved in a mixed solvent consisting of ethanol and water, sonicated for 30 min, and placed in a 250 ml thermometer, stirrer and condenser. Inside the four-neck bottle, protected by nitrogen, pre-dispersed at 70 ° C for 30 min, then slowly drip The monomer styrene to which the initiator azodiethylbutyronitrile was dissolved was reacted at 70 ° C for 12 h to obtain a sample of the monodisperse polymerized composite microsphere emulsion. The emulsion sample was sedimented by centrifugation, the supernatant was discarded, the lower microspheres were washed with ethanol, centrifuged, and washed, and this was repeated 5 times. The washed microspheres were poured into a culture medium and dried in a vacuum oven at 60 ° C for 24 h to obtain oxidized/polystyrene composite nanospheres, that is, electrophoretic particles, to complete the preparation of the oxidized functional double sphere. The above tetrachloroethylene suspension containing 10% by weight of electrophoretic particles was ultrasonically shaken for 50 minutes. Under ultrasonic vibration, solvent blue and 2 wt% byk 163 charge dispersant, which accounted for 1 wt% of the suspension, were slowly added in portions, and ultrasonically shaken for 30 minutes to obtain an electronic ink.

Comparative Example 6 Weighed a moderate amount of oxidized nano-microspheres from the above examples, and prepared tetrachloroethylene solution of the same concentration of oxidized nanospheres in the same manner as in the above examples, using tetrachloroethylene as a solvent, and ultrasonically oscillated for 50 minutes. Fully diffuse, let stand for 90 days, extract the upper layer of turbid liquid, use tetrachloroethylene as a reference solution, and record the light transmittance. The results are shown in the table below. Table 12 Example 6 Electron ink stability test before and after oxidation of microspheres

The above is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims.

Claims

claims

1. An electronic ink, including an oil-soluble dye and an electrophoretic liquid containing electrophoretic particles, wherein the electrophoretic particles include oxidized microspheres and an ionized coating layer coating the oxidized microspheres.

2. The electronic ink of claim 1, wherein the ionized coating layer is ionized polyethylene wax.

3. The electronic ink of claim 1, wherein the ionized coating layer contains ionized epoxy groups.

4. The electronic ink of claim 1, wherein the ionized coating layer contains ionized ^pyridyl groups.

5. The electronic ink of claim 1, wherein the ionized coating layer is ionized polyvinylpyrrolidone.

6. The electronic ink of claim 1, wherein the ionized coating layer is ionized polystyrene.

7. The electronic ink according to claims 1 to 6, wherein the electrophoresis liquid is a liquid aliphatic hydrocarbon, a liquid alcohol with 7 or more carbon atoms, a liquid ester with 7 or more carbon atoms, or a liquid with 4 or more carbon atoms. One or more than two types of organic acids.

8. The electronic ink of claims 1 to 6, wherein the oil-soluble dye includes oil-soluble blue, oil-soluble yellow, oil-soluble red, oil-soluble green or oil-soluble violet; the mass percentage of the oil-soluble dye is 0.5-10%.

9. A method for preparing electronic ink, which includes the following steps:

1) Prepare a suspension of oxidized microspheres with a coating layer with uniform particle size;

2) Add the prepared suspension of oxidized microspheres with a coating layer and a surface ionizing agent for surface ionization of the oxidized particles with a coating layer into an organic solvent, and after dispersion, form an electrophoresis solution containing electrophoretic particles. , the electrophoretic particles in the electrophoresis solution include oxidized microspheres and an ionized coating layer coated on the oxidized core;

3) Add an oil-soluble dye to the electrophoresis solution containing electrophoresis particles, and form the electronic ink after ultrasonic vibration.

10. The method for preparing electronic ink according to claim 9, wherein the preparation of the oxidized microsphere suspension with a coating layer includes the following steps: 51) Disperse the oxide nanoparticles in the solvent to form a suspension;

52) Heat the suspension to 80 to 120°C, add polyethylene wax to the suspension, and after stirring, lower to room temperature to obtain the oxidized microsphere suspension with a coating layer.

11. The method for preparing electronic ink according to claim 9, wherein the preparation of the oxide microsphere suspension with a coating layer includes the following steps:

S I) dispersing oxidized nanospheres in a solvent to form a suspension;

S II) Add the oxidant solution under the conditions of stirring and protective gas, add the mixed solution I and the reducing agent solution, and adjust the pH range to 6.0~8.0 after the reaction is completed to obtain the oxidized microsphere suspension with a coating layer liquid, and the mixed liquid I is a mixed liquid including diethylbenzene and glycidyl methacrylate.

12. The method for preparing electronic ink according to claim 9, wherein the preparation of the oxide microsphere suspension with a coating layer includes the following steps:

K1) Disperse the oxidation nanoparticles in the solvent to form a suspension;

K2) Under stirring conditions, add the oxidant solution, pass in the protective gas, add the mixture of divinylphenylpyridine and 4-vinylpyridine and the reducing agent solution to obtain the oxidation microsphere suspension with a coating layer .

13. The method for preparing electronic ink according to claim 9, wherein the preparation of the oxidized ink suspension with a coating layer includes the following steps:

Q1) Disperse oxidized nanoparticles in a solvent containing sodium hexametaphosphate, adjust the pH range to 6.0-8.0, and form a suspension;

Q2) Add polyvinylpyrrolidone to the suspension, and ultrasonically disperse the suspension to which polyvinylpyrrolidone is added to obtain the oxidized microsphere suspension with a coating layer.

14. The method for preparing electronic ink according to claim 9, wherein the preparation of the oxide microsphere suspension with a coating layer includes the following steps:

D1) Disperse the oxide nanoparticles in a mixed solvent composed of ethanol and water to form a suspension;

D2) Add monomer styrene dissolved in the initiator azodiethylbutyronitrile dropwise into the suspension for reaction at 50-90°C to obtain the oxidized microsphere suspension with a coating layer.