KR100763953B1 - Colored electornic ink nanoparticles for electronic displays and preparation thereof - Google Patents

Abstract

Colored electronic ink nanoparticles for electronic displays are provided to have clear colors and high electrophoretic mobility and embody clear colors on e-papers. Colored electronic ink nanoparticles for electronic displays are prepared by the steps of: cross-linking methyl methacrylate, ethyleneglycol dimethacrylate, and [2-(methacryloxy)ethyl]trimethyl ammonium chloride] by a non-emulsion copolymerization method using 2,2'-azobis(2-methylpropionamidine)dihydrochloride as an initiator to prepare poly(methyl methacrylate-co-ethyleneglycol dimethacrylate-co-[2-(methacryloxy)ethyl]trimethyl ammonium chloride) nanoparticles; adding hexamethylenediamine to the nanoparticles, stirring and reacting the admixture at room temperature for 11-13 hours to prepare amine group-containing nanoparticles(NH2-PMMA); and dyeing the amine group-containing nanoparticles with a disperse dye solution containing water and a disperse dye in a weight ratio of 5-40:1.

Description

Colored electornic ink nanoparticles for electronic displays and preparation according to electronic paper color

1 is cross-linked poly (methyl methacrylate-co-ethylene glycol dimethacrylate-co- [2- (methacryloxy) ethyl] trimethyl ammonium chloride) nanoparticles prepared according to the present invention (hereinafter referred to as' PMMA Scanning electron microscope (SEM) photographs of the nanoparticles' are shown.

Figure 2 shows the DSC data of the crosslinked PMMA nanoparticles prepared according to the present invention.

Figure 3 shows a scanning electron micrograph of the nanoparticles stained according to the present invention. (A) is red, (b) is yellow, and (c) is blue, respectively.

Figure 4 (a) is a PMMA nanoparticles prepared according to the present invention, Figure 4 (b) shows a scanning electron micrograph of the nanoparticles stained in red.

Figure 5 shows the results of UV / visible spectrum analysis of PMMA nanoparticles prepared according to the present invention, and red, blue and yellow stained nanoparticles.

Figure 6 shows the PL spectrum analysis results of the nanoparticles, and red, blue and yellow stained nanoparticles prepared according to the present invention.

7 (a) and 7 (b) show the color differences when the driving voltage of 100 V / mm is reversed with respect to the prototype manufactured using the nanoparticles prepared according to the present invention, respectively. It is red.

The present invention relates to multicolor nanoparticles capable of realizing color on an e-paper, and a method of manufacturing the same, in particular a dyeing method.

New displays, commonly referred to as electronic paper displays or electrophoretic displays, are known as displays that combine the advantages of paper and modern displays.

Electrophoresis is a phenomenon in which when a particle is suspended in a medium (dispersion medium), the particles are electrically charged, and when an electric field is applied to the charged particles, they move through the dispersion medium to electrodes having opposite charges. Electrophoretic particles for use in electronic inks or electrophoretic displays using such a phenomenon are commonly used titanium oxide (Titania) as a white pigment, carbon black widely used in ink as a black pigment. In the case of multicolored pigments for color realization, many researches and developments such as pigments consisting of salts of ionic dyes and inorganic compounds are underway, but there are no suitable pigments yet. In addition, since the shape of the electrophoretic particles and the number of aggregates are uneven, it is difficult to control the amount of dispersion and to uniformly disperse it.

In the present invention, a disperse dye generally used for dyeing fibers is applied to manufacture multicolor electrophoretic particles, thereby implementing a vivid color electronic paper display.

The present invention relates to multicolored nanoparticles that are charged for color realization of electrophoretic displays, in particular multicolored poly (methyl methacrylate-co-ethylene glycol dimethacrylate-co- [2- (methacryloxy) ethyl] trimethyl Ammonium chloride) nanoparticles (hereinafter referred to as 'PMMA nanoparticles').

It is also an object of the present invention to provide multicolor PMMA nanoparticles in which the shape and number of aggregates of the particles are uniform so that the amount of dispersion can be easily controlled and dispersed.

In addition, the present invention is a multi-color PMMA using the property that the carbonyl group and the dispersion dye of the polyester fiber is dyed by hydrogen bonds or van der waals interaction using the most commonly used disperse dyes when dyeing fibers It is intended to provide a method for dyeing nanoparticles.

In order to achieve the above object, according to a preferred embodiment of the present invention, poly (methyl methacrylate-co-ethylene glycol dimethacrylate-co- [2- (methacryloxy) ethyl] trimethyl ammonium having an amine group introduced therein Chloride) nanoparticles are provided with multicolored poly (methyl methacrylate-co-ethylene glycol dimethacrylate-co- [2- (methacryloxy) ethyl] trimethyl ammonium chloride) nanoparticles.

According to another suitable embodiment of the present invention, the azo dye C. I. disperse dye red 152, C.I. Disperse dyes Yellow 241, and C.I. Disperse dye blue 73 is used.

According to another suitable embodiment of the present invention, the electrophoretic mobility of the produced multicolor nanoparticles is 8.3 × 10 ⁻⁶ .

According to another suitable embodiment of the present invention, methyl methacrylate, ethylene glycol dimethacrylate and [2- (methacryloxy) ethyl] trimethyl ammonium chloride] are disclosed as initiator 2,2'-azobis (2-methyl Copolymer poly (methyl methacrylate-co-ethylene glycol dimethacrylate-co- [2- (methacryloxy) ethyl] trimethyl ammonium chloride by crosslinking by an emulsification-free copolymerization method using propionamidine) dihydrochloride ) Preparing nanoparticles; Hexamethylenediamine was added to the nanoparticles, followed by stirring at room temperature for 11 to 13 hours to prepare nanoparticles (NH ₂ -PMMA) to which amine groups were introduced; And dyeing the nanoparticles having the amine group introduced therein with a disperse dye solution having a water: dispersion ratio of 5 to 40: 1 in a weight ratio of poly (methyl methacrylate-co-ethylene glycol dimethacrylate). A method for preparing -co- [2- (methacryloxy) ethyl] trimethyl ammonium chloride) nanoparticles is provided.

According to another suitable embodiment of the invention, the dyeing is preferably carried out for 1 hour at a temperature of 110 ℃.

Hereinafter, the present invention will be described in more detail.

According to the present invention, the surface of PMMA nanoparticles is positively charged on the surface of PMMA nanoparticles using an emulsion-free emulsion polymerization method, and an amine group is introduced into the nanoparticles by using an aminolysis method. Further, it is possible to provide multi-color PMMA nanoparticles that can be dyed with a disperse dye to improve the charge on the surface of the nanoparticles, thereby improving electrophoretic mobility and realizing vivid electronic paper color.

Emulsified emulsion polymerization is known as one of the useful methods for producing monodisperse polymer particles having nanoscale diameters. By using this method, the charged group of the initiator can be present on the surface of the prepared nanoparticles to stabilize the particles and at the same time give the charge.

Disperse dyes are dyes which are mainly used for dyeing hydrophobic fibers in the state of being dispersed in water as a hydrophobic dye insoluble in water. In other words, it is not dissolved at all or does not melt well to make a fine powder, using a dispersing agent such as a surfactant to disperse to close to colloidal state in water, dye is diffused into the polymer chain gap dyeing. Instead, one or more functional groups such as NH ₂ or OH are introduced. This is due to the fact that the dyes disperse dyes on the fibers due to hydrogen bonds and van der waals interactions.

For example, dyeing of fibers may include dyeing of carbonyl groups and dispersion dyes of the most common polyester fibers by hydrogen bonds or van der Waals interactions. It was provided a method for staining with PMMA nanoparticles with a disperse dye.

To prepare the nanoparticles of the present invention, methyl methacrylate (hereinafter referred to as 'MMA', 99%) and ethylene glycol dimethacrylate (hereinafter referred to as 'EGDMA', 98%) were passed through an alumina column to inhibit the polymerization. I used to remove it.

MMA, EGDMA and [2- (methacryloxy) ethyl] trimethyl ammonium chloride (hereinafter referred to as 'MOTAC') are referred to as 2,2'-azobis (2-methylpropionamidine) dihydrochloride (hereinafter referred to as 'AIBA'). Copolymer nanoparticles crosslinked by an emulsion-free copolymerization method were prepared. It is preferable that polymerization temperature is 60-80 degreeC, Preferably it is 70 degreeC, and polymerization time is 20 hours. The prepared nanoparticles are charged because they use an emulsion-free emulsion polymerization method.

The MOTAC used in the present invention charges the surface of the prepared nanoparticles, controls the size and charge density of the nanoparticles, and improves stability.

Scanning electron microscopy results of the size and dispersion of PMMA nanoparticles prepared according to the present invention are shown in FIG. 1. According to FIG. 1, the diameters of the monodisperse polymer nanoparticles vary depending on the concentration of MOTAC used, and the particle size decreases as the concentration of MOTAC increases. Therefore, the size of the nanoparticles to be prepared can be controlled by adjusting the concentration of MOTAC to be used.

The nanoparticles thus prepared are introduced into the nanoparticles by using an aminolysis as shown in the following scheme to improve the surface charge of the particles. As a result, electrophoretic mobility is improved. This is because the amine groups introduced into the nanoparticles due to the amine decomposition reaction are induced to have a positive charge by a charge control agent which adds the electronic paper display to the dispersion medium during electric driving. In the present invention, a charge control agent under the trade name OLOA 1200 (Polybutene Succinimide) is preferably used. The gaamine decomposition reaction of the present invention is carried out by dispersing the copolymerized nanoparticles in water, adding an amine and reacting with stirring at room temperature for 11 to 13 hours.

[Scheme]

After the emulsion-free polymerization method and the amine decomposition reaction, the charged particles are dyed using a disperse dye to prepare multicolor nanoparticles represented by the following formula (1).

[Formula 1]

The type of the disperse dye for dyeing the PMMA nanoparticles introduced with the amine group of the present invention is not particularly limited, and any disperse dye for dyeing fibers or the like can be used. In the present invention, CI dispersion dye red 152 and CI dispersion dye yellow 241, which are azo dyes represented by the following Chemical Formula 2, and CI dispersion dye blue 73, which are anthraquinone dyes, are specifically used. These dyes all have polar functional groups such as NH ₂ , —NO ₂ and —CN. The polar functional groups present in the dye allow for dyeing by hydrogen bonding with the carbonyl group of the PMMA nanoparticles.

[Formula 2]

The dyeing of the nanoparticles is performed by adding a dye to a solution in which the nanoparticles are dispersed, and the water: dispersant is dyed with a dye solution having a weight ratio of 5 to 40: 1. Since the dyeing method using a disperse dye is performed at a high temperature of about 80 to 125 ℃, the degree of crosslinking should be adjusted in consideration of the stability of the nanoparticles during the dyeing process. In the present invention, the content of the crosslinking agent is preferably added in an amount of 4-6% by weight based on the monomer, and more preferably 5% by weight, for proper degree of crosslinking. As the particles are crosslinked, the glass transition temperature is increased with respect to the glass transition temperature (Tg) of the uncrosslinked PMMA through thermal analyzer DSC data. This data is shown in FIG.

According to Figure 2 it can be seen that the glass transition temperature (Tg) of the cross-linked nanoparticles is about 130 ℃. Therefore, since the nanoparticles of the present invention are dyed at a temperature of about 80 to 125 ° C, preferably 110 ° C, it is possible to ensure the stability of the particles.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the embodiments according to the present invention can be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. do.

Example

Example 1

Preparation of Nanoparticles

In 150 ml of water, 14.25 g of MMA, 0.765 g of EGDMA and 0.06 g of MOTAC ([2- (Methacyloxy) ethyl] trimethyl ammonium chloride) were used as initiators and 0.075 g of AIBA (2,2'-azobis (2-methylpropionamidine) dihydrochloride). Copolymer nanoparticles are prepared by crosslinking by an emulsion-free copolymerization method. A 250 ml round flask equipped with a stirrer, reflux condenser and nitrogen injection system was used and AIBA initiator was added to the reactor with stirring at 300 rpm. Then, the polymerization was carried out at 70 ° C. for 20 hours. After the polymerization, the particles were purified by centrifugation / redispersion three times or more in distilled water. Finally lyophilized to obtain nanoparticles.

In the decomposition reaction  Nanoparticle surface modification

10 g of polymer particles having a diameter of about 170-190 nm were dispersed in 100 ml of water. 10 g of hexamethylene diamine was added and reacted with stirring at room temperature for 12 hours. The amine modified (introduced) particles (NH ₂ -PMMA) were purified by washing several times.

NH ₂ - PMMA  Dyeing of particles

0.72 g of a disperse dye was dispersed in 90 ml of an aqueous solution in which 9 g of NH ₂ -PMMA particles were dispersed, and then adjusted to pH 4.5 with an aqueous 30 wt% acetic acid solution. In a 250 ml round flask, the dye was first added to the solution in which the particles were dispersed, and the pH of the solution was adjusted with an aqueous 30% acetic acid solution. After the temperature was raised to 110 ° C. at a rate of 1 ° C./min near pH 4.5, the temperature was maintained for 1 hour and dyed, and the temperature of the dye solution was lowered at room temperature. The stained particles were washed by centrifugation with water and lyophilized.

,

Evaluation of the Particles Prepared

The shape and dispersion state of the nanoparticles prepared according to the present invention were examined by electron scanning microscope (SEM). The heat transition temperature was measured under a nitrogen atmosphere by heating at a rate of 10 ° C./min using a thermal analyzer DSC 2920. Absorbance measurement was performed using US / VIS spectrometer. FTIR spectral measurements were taken. Electrophoretic mobility was determined by dynamic light scattering (DSC) with the ELS-8000.

The size and dispersion of PMMA nanoparticles prepared according to the present invention were examined by scanning electron microscopy, and the results are shown in FIG. 1.

After staining, the size and morphology of the nanoparticles were examined by scanning electron microscopy, and the results are shown in FIG. 3.

The SEM image of FIG. 4 shows undyed PMMA nanoparticles (a) and nanoparticles (b) stained in red. According to Figure 4, it can be seen that the morphology of the particles (morphology) is maintained as it goes through the process of hot dyeing / centrifugation / freeze drying.

UV / visible spectrum and PL (photoluminescence) spectrum were measured to analyze the color of the stained particles by wavelength. The results are shown in FIGS. 5 and 6, respectively. First, in the UV / Visible spectrum, PMMA nanoparticles stained with blue, red and yellow were observed at 584 nm and 630 nm, 524 nm and 434 nm, respectively. In the PL spectrum, the peaks with the highest intensity were observed, respectively, and the λmax values of the blue, yellow, and red particles appeared in the order of 318 nm, 437 nm, and 527 nm, respectively, and correspond to the wavelength range indicated by the original color. It was.

As a result of examining the electrophoretic mobility of the nanoparticles prepared according to the present invention, it can be seen that the electrophoretic mobility of the nanoparticles subjected to the amine decomposition and dyeing is greatly improved. The test results are shown in Table 1.

Table 1. Electrophoretic Data of Particles

Zeta potential (mV) Mobility (㎠ / Vs Electric field (V / cm) PMMA Particles - - 158.4 Disperse Dyes 14.0 2.3 × 10 ^-6 159.1 Gamine decomposition reaction 28.7 7.1 × 10 ^-6 158.4 Gaamine Decomposition + Dispersant 34.6 8.3 × 10 ^-6 158.6

Color particles stained with disperse dyes already exhibit positive charges before dyeing, since cationic initiators and monomers have been used since polymerizing the particles. The surface charge value of the particles was measured using a zeta analyzer. The zeta potential was 16.70 mV, and the mobility was 3.810x10-6 cm2 / Vs. At this time, the medium is a mixed solution of isoparag G / halocarbon oil (4: 3) and OLOA 1200 (10wt%) was used as a charge control agent.

In addition, prototypes were made of ITO glass using the same medium to perform driving experiments. In order to check the driving properties of the particles more easily, the color difference between the red particles and the red particles was observed when the blue dye was dissolved in the medium. . As a result of the experiment, the response speed was slow at the driving voltage of about 50 V / mm, but the driving was confirmed. 7 (a) and 7 (b) show color differences when the driving voltage of 100 V / mm is reversed, respectively. In the driving test, the interval between the ITO glasses was about 350 μm.

Although the present invention has been described in detail only with respect to specific examples, it is apparent to those skilled in the art that various changes and modifications can be made within the technical spirit of the present invention, and the present invention is limited by these modifications and variations. This doesn't work.

The nanoparticles prepared according to the present invention have a vivid color, are charged, and have high electrophoretic mobility. Therefore, using the nanoparticles of the present invention can realize a vivid color in the electronic paper.

Claims (4)

In the multi-color nanoparticles for electronic paper, Poly (methyl methacrylate-co-ethylene glycol dimethacrylate-co- [2- (methacryloxy) ethyl] trimethyl ammonium chloride) nanoparticles to which an amine group is bound by a amine decomposition reaction with hexamethylenediamine Multi-colored poly (methyl methacrylate-co-ethylene glycol dimethacrylate-co- [2- (methacryloxy) ethyl] trimethyl ammonium chloride) nanoparticles characterized by dyes dispersed in particle. [Formula 1]

The disperse dye according to claim 1, wherein the disperse dye is an azo dye. Disperse dyes Yellow 241, and C.I. A multicolored poly (methyl methacrylate-co-ethylene glycol dimethacrylate-co- [2- (methacryloxy) ethyl] trimethyl ammonium chloride) nanoparticle, characterized by being disperse dye blue 73. The multicolored poly (methyl methacrylate-co-ethylene glycol dimethacrylate-co- [2- (meth) according to claim 1, wherein the electrophoretic mobility of the multicolored nanoparticles is 8.3 × 10 ⁻⁶ . Krilloxy) ethyl] trimethyl ammonium chloride) nanoparticles. In the manufacturing method of multi-color nanoparticles for electronic paper, Methyl methacrylate, ethylene glycol dimethacrylate and [2- (methacryloxy) ethyl] trimethyl ammonium chloride] were free of initiator 2,2'-azobis (2-methylpropionamidine) dihydrochloride. Crosslinking by emulsion copolymerization to prepare copolymer poly (methyl methacrylate-co-ethylene glycol dimethacrylate-co- [2- (methacryloxy) ethyl] trimethyl ammonium chloride) nanoparticles; Hexamethylenediamine was added to the nanoparticles, followed by stirring at room temperature for 11 to 13 hours to prepare nanoparticles (NH ₂ -PMMA) to which amine groups were introduced; And Multi-colored poly (methyl methacrylate-co-ethylene glycol dimethacrylate- comprising dyeing the nanoparticles having the amine group introduced therein with a disperse dye solution having a water: dispersant at a weight ratio of 5 to 40: 1. co- [2- (methacryloxy) ethyl] trimethyl ammonium chloride) method for preparing nanoparticles.

Images