KR20130063972A - Color electrophoretic particle, electrophoretic display using the same and method for manufacturing electrophoretic display - Google Patents

Abstract

PURPOSE: A color electrophoretic particle, an electrophoretic display device using the same, and a manufacturing method thereof are provided to form the color electrophoretic particle as a particle separated from a white electrophoretic particle, thereby manufacturing the color electrophoretic particle simply and easily. CONSTITUTION: A color electrophoretic particle(10) includes a core part and a shell part. The core part is comprised of a color pigment(12) of a chromatic color. The shell part surrounds the color pigment. The shell part is comprised of a binder(14) which includes a charge control agent(16) and a surfactant layer(18).

Description

COLOR ELECTROPHORETIC PARTICLE, ELECTROPHORETIC DISPLAY USING THE SAME AND METHOD FOR MANUFACTURING ELECTROPHORETIC DISPLAY}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophoretic display device, and more particularly, to a color electrophoretic particle capable of improving reflectance and color reproducibility as well as securing bistable stability, an electrophoretic display device using the same, and a manufacturing method thereof.

An electrophoretic display (EPD) is an image display device using a phenomenon in which colloidal particles included in an insulating fluid move in either polarity between a pair of electrodes to which an electric field is applied. The electrophoretic display device applies a voltage to a pair of opposing electrodes to display white when the white ink particles collect on the display surface and black when the black ink particles collect. Unlike the liquid crystal display, the electrophoretic display does not use a backlight light source, and has a wide viewing angle, high reflectance, and low power consumption. However, since the backlight does not use a light source, the contrast ratio of the pixels is lowered in a dark place, which may not function as a display device.

In addition, the electrophoretic display device has a bistable stability that maintains the color before removing the electric field even when the applied electric field is removed, and thus has low power consumption. However, bi-stability may be deteriorated depending on the design of the electrophoretic particles and the structure of the display device, which is caused by aggregation of charged particles for a long time, and various methods have been proposed to prevent this.

U.S. Patent No. 6,017,584, US 7,012,735 proposes a display device using electrophoresis by carrying two colors of electrophoretic particles charged with black and white and an insulating fluid in a capsule, but it is difficult to realize multicolor. It is possible to realize only the contrast of a single color, and to implement the color, the color filter should be applied to the upper part like the liquid crystal display device, so the reflectance is low. And there is a problem that the sharpness of the color is lowered.

In order to compensate for this, US Pat. No. 7,141,688 proposes a method of implementing a multicolor by introducing a dye stabilizer, but there is a problem in that driving characteristics are increased due to an increase in driving voltage and generation of particles between partition walls. Japanese Patent Application Laid-Open Nos. 2006-259771 and 2002-0075556 have proposed a method of injecting electrophoretic particles into a pattern called a microcup, but the electrophoretic particles are not colored but the dispersion fluid implements color. Because of this, color reproduction is low, and there is a shortage of contrast ratio.

Korean Patent Laid-Open Publication No. 2005-0055557 introduces a method of microencapsulating a pigment with a colorant in a white particle when producing multicolored color electrophoretic particles, but the particle size is uneven due to an increase in crystallinity and particle size of the pigment particle. In addition, there is a problem in that the light transmittance is inhibited and the reflectance, color reproducibility and bistable stability are inferior.

The present invention has been made to solve the conventional problems, the problem to be solved by the present invention is to improve the reflectance and color reproducibility and to secure bistable color electrophoretic particles and color electrophoretic display device and its It is to provide a manufacturing method.

In order to solve the above problems, the color electrophoretic particles according to the present invention and the core portion consisting of a colored pigment of the color; A shell portion is formed of a binder surrounding the color pigment and comprising a charge control agent.

The color electrophoretic display device according to the embodiment of the present invention includes a plurality of pixels injected with color electrophoretic ink in which a plurality of electrophoretic particles having different polarities are dispersed in an insulating fluid in a suspended state; The electrophoretic particles comprise the color electrophoretic particles.

The plurality of pixels comprises white, red, green, blue pixels; White ink including white electrophoretic particles and black electrophoretic particles is injected into the white pixel, and red ink including red electrophoretic particles, white electrophoretic particles and black electrophoretic particles is injected into the red pixel, The green pixel is injected with green ink including green electrophoretic particles, white electrophoretic particles, and black electrophoretic particles, and the blue pixel includes blue electrophoretic particles, white electrophoretic particles, and black electrophoretic particles. Is injected.

Each of the red, green, and blue electrophoretic particles has a specific gravity smaller than that of the white electrophoretic particles.

Each of the white, red, green, and blue electrophoretic particles includes a negative charge control agent, and the black electrophoretic particles include a positive charge control agent.

In the method of preparing a color electrophoretic particle dispersion according to an embodiment of the present invention, a color electrophoretic particle having a core part composed of the color pigment and a shell part composed of the binder is dispersed by dispersing a color pigment in a dispersant, a binder and an organic solvent. Preparing a color electrophoretic particle dispersion dispersed in the dispersant and the organic solvent.

The color pigment may be an organic pigment, an inorganic pigment, or an organic or inorganic salt with zinc oxide, titanium oxide, titanium bag, CIPigment RED254, CIPigment RED177, CIPigment RED122, CIPigment YELLOW139, CIPigment BLUE15: 1, CIPigment BLUE15: 3 CIPigment BLUE15: 4, CIPigment BLUE15: 6, CIPigment VIOLET23, CIPigment GREEN36, CIPigment YELLOW138, CIPigment YELLOW139, CIPigment YELLOW150.

The organic solvent is propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol mono acetone methyl ethyl ketone cyclonucleosanone ethanol methylene chloride ethyl ether acetate, propylene glycol monoethyl ether, ethoxypropionic acid, xylene, toluene, butyl One or two or more selected from acetate and butanol.

The dispersant and the binder are at least one selected from polyesters, polyacrylates, and polyurethanes.

The organic solvent may include 10 to 90 parts by weight, the dispersant and the binder may include 5 to 80 parts by weight, and the color pigment may include 1 to 10 parts by weight.

The size of the color electrophoretic particles is 30 ~ 500nm.

A method of manufacturing a color electrophoretic display device according to an embodiment of the present invention includes the steps of preparing a black electrophoretic particle dispersion and a white electrophoretic particle dispersion; Preparing a color electrophoretic particle dispersion according to any one of claims 9 to 17; Preparing a color electrophoretic particle suspension by mixing the white electrophoretic particle dispersion and the color electrophoretic particle dispersion; Preparing a white ink by mixing the black electrophoretic particle dispersion and the white electrophoretic particle dispersion; Preparing a color ink by mixing the black electrophoretic particle dispersion and the color electrophoretic particle suspension; Forming a partition on the first substrate on which the first electrode is formed to provide each pixel space; Injecting the white, red, green, and blue inks into the pixel spaces, respectively; Bonding and sealing a second substrate having a second electrode formed thereon on the first substrate to which the ink is injected.

The color particle suspension includes 1 to 50 parts by weight of the color particle dispersion relative to the white particle dispersion.

The color particle suspension includes 1 to 50 parts by weight of the black particle dispersion relative to the white particle dispersion.

The size of the pigment nucleus in the color particles is 30-400 nm.

In the present invention, white electrophoretic particles and color electrophoretic particles having white and colored pigments as nuclei are prepared, respectively. By forming the color electrophoretic particles into particles separate from the white electrophoretic particles, color electrophoretic particles can be produced simply and easily, and color electrophoretic particles can be prepared by changing the type and content of the dispersion by introducing a color pigment dispersion. By controlling the size and the amount of charge separately, it is possible to improve color reproducibility and reflectance and to secure excellent bistable stability.

1 is a view schematically showing a color electrophoretic particle structure according to an embodiment of the present invention.
2 is a cross-sectional view of a color electrophoretic display device according to an exemplary embodiment of the present invention.

A general color electrophoretic particle has a structure in which a color pigment is included as a colorant in a binder resin of a white electrophoretic particle, whereas the color electrophoretic particle according to the present invention is like a white electrophoretic particle having a white pigment as a core (core). Since the color pigment is used as the core (core), particle size control and charge amount control are easy.

1 is a view schematically showing the structure of colored electrophoretic particles according to the present invention.

The color electrophoretic particles shown in FIG. 1 have a core / shell structure, a core portion composed of colored color pigments 12), and a polymer binder 14 encapsulating the color pigments 12 in a capsule form. It consists of a shell part consisting of The polymer binder 12 includes a charge control agent 14, a surface active layer 16, and the like.

The color pigments 12 are zinc oxide, titanium oxide, titanium bag, CIPigment RED254, CIPigment RED177, CIPigment RED122, CIPigment YELLOW139, CIPigment BLUE15: 1, CIPigment as organic pigments, inorganic pigments, or organic inorganic salts. BLUE15: 3 CIPigment BLUE15: 4, CIPigment BLUE15: 6, CIPigment VIOLET23, CIPigment GREEN36, CIPigment YELLOW138, CIPigment YELLOW139, CIPigment YELLOW150.

The polymer binder 12 includes at least one of polyester, polyacrylate, and polyurethane.

In the method of manufacturing color electrophoretic particles of the present invention, color pigment dispersions may be introduced to change the type and content of the dispersions to easily control the size and amount of the color electrophoretic particles. Color electrophoretic particles, the color pigment is dispersed by the polymer main chain and the at least one polar group bonded to the main chain of the polymer binder, which occupies 60 to 80% of the electrophoretic particles, and collects the charge control agent dispersed in the polymer binder Since it contains a polar group of the main chain and a different side chain, it is possible to control the amount and type of the charge control agent by controlling the amount of the polar group contained in the main chain and the side chain.

Accordingly, the color electrophoretic particles according to the present invention can produce particles having a uniform size than conventional color electrophoretic particles including a colorant in a binder of white electrophoretic particles, thereby improving color reproducibility and reflectance. In addition, it is possible to secure driving characteristics such as bistable by adjusting particle size and charge amount for each color.

In order to disperse a polymer binder, a color pigment, a solvent, and a charge control agent, the present invention primarily disperses a color pigment by the dispersing force of the polar group by using different polar groups of the main chain and the side chain, and injects the charge control agent secondly. To second dispersion using a polar group to prepare a color electrophoretic particle dispersion. The color electrophoretic particles and dispersion preparation method according to the present invention is prepared by a method similar to white or black electrophoretic particles and dispersions thereof.

Black, white and color pigments are crystalline aggregates and require a separate dispersion process. If the particles are not dispersed, electrophoretic particles are not possible because the size of the pigment particles is several microns to several tens of microns, and thus, pigment dispersions of several tens of nanometers are prepared through a separate dispersion process. The dispersion uses one of a roller mill, a jet mill, a vertical-bead mill, a horizontal-bead mill, an ultrasonic grinder, and any dispersion equipment. You can also use.

In the method for producing color electrophoretic particles and dispersion according to the present invention, a dispersion in which a color pigment is dispersed using a primary solvent is used to facilitate bonding with a polar group of a main chain using a hydrophobic group having a large molecular weight, and the dispersion surrounds a charge control agent. Colored electrophoretic particles are prepared using side chains in the form. The type and amount of the charge control agent used at this time can be adjusted by changing the polar group content of the main chain and the side chain. Pigment dispersion time, charge amount and particle size can be adjusted differently according to the type and content of the polar group used. The size of the color electrophoretic particles, white electrophoretic particles and black electrophoretic particles according to the present invention is to be included in the 30 ~ 700nm range (30 ~ 500nm range). If it is smaller than this range, the reflectance decreases, and if it is larger than this range, the response speed is lowered during driving, which requires a lot of energy.

The organic solvent used in the method for producing the color electrophoretic particle dispersion according to the present invention is propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol mono acetone methyl ethyl ketone cyclonucleosanone ethanol methylene chloride ethyl ether acetate, propylene glycol Monoethyl ether, ethoxypropionic acid, xylene, toluene, butyl acetate, and butanol. The organic solvent contains 10 to 90 parts by weight based on 100 parts by weight of the pigment dispersion.

The dispersant and the binder used in the method for producing the color electrophoretic particle dispersion according to the present invention contain 5 to 80 parts by weight based on 100 parts by weight of the pigment dispersion. The dispersant and the binder include at least one of polyester, polyacrylate, and polyurethane.

The color pigment used in the method for producing the color electrophoretic particle dispersion according to the present invention contains 1 to 10 parts by weight based on 100 parts by weight of the color electrophoretic particle dispersion.

Hereinafter, embodiments of the present invention will be described a typical black, white, red, green, blue electrophoretic particles and dispersion production method and method of the electrophoretic display device, which is only an example, so the scope is limited or limited. I never do that.

Example  1: Preparation of Black Electrophoretic Particle Dispersion

10 g of a binder resin using a binder containing 1% by weight of a polar group in the main chain and side chain was dissolved in 100 g of ethyl acetate solvent, and 3 g of black pigment (carbon black) and 100 g to 5000 g of 0.3 to 3 mm size of zirconia ball were included. Disperse first using a disperser for 48 hours. It is then subjected to secondary dispersion with 3 g of the positive charge control agent under the same conditions. The ball was removed from the secondary dispersion by using a diluent (ethyl acetate, 10% by weight of anti-flocculation agent), and then in a reactor using a low viscosity disperser for 20 minutes to 80 ° C for 1 minute to 30 minutes under conditions of 100 to 5000 RPM. The particles are mixed and the particles are dispersed at high speed in an isoparaffinic solvent. Accordingly, a black electrophoretic particle dispersion having black electrophoretic particles having a constant size and having a positive charge is dispersed.

Example  2: Preparation of White Electrophoretic Particle Dispersions

Dissolve 10 g of binder resin using a binder containing 1% by weight of a polar group in the main chain and side chain in 100 g of ethyl acetate solvent, and 3 g of white pigment (titanium oxide), 3 g of negative charge charge regulator and 100 g to 5000 g of 0.3-3 mm size of zirconia ball. 1 hour dispersion using 2 to 48 hours disperser. It is then subjected to secondary dispersion with 3 g of negative charge control agent under the same conditions. Remove the ball from the secondary dispersion by using a diluent (ethyl acetate, 10% by weight of anti-flocculation agent), and then in the reactor using a low viscosity disperser in the range of 20 ℃ ~ 80 ℃, 1 ~ 30 minutes under 100 ~ 5000 RPM conditions While the particles are dispersed at high speed in an isoparaffinic solvent. Accordingly, a white electrophoretic particle dispersion having white electrophoretic particles having a constant size and having a negative charge therein is prepared.

Example  3: Preparation of Red Electrophoretic Particle Dispersion (1) and Suspension (1)

Dissolve 10 g of the binder resin using a binder containing 1% by weight of a polar group in the main chain and side chain in 100 g of ethyl acetate solvent, 3 g of red pigment (organic pigment: Red 254), 3 g of negative charge charge regulator, and 100 g of 0.3-3 mm size of zirconia ball. Including 1 ~ 5000g 2 hours ~ 48 hours dispersion using a disperser. It is then subjected to secondary dispersion with 3 g of negative charge control agent under the same conditions. Remove the ball from the secondary dispersion by using a diluent (ethyl acetate, 10% by weight of anti-flocculation agent), and then in the reactor using a low viscosity disperser in the range of 20 ℃ ~ 80 ℃, 1 ~ 30 minutes under 100 ~ 5000 RPM conditions While the particles are dispersed at high speed in an isoparaffinic solvent. Accordingly, a red electrophoretic particle dispersion 1 having a uniform size and having a negatively charged red electrophoretic particle dispersed therein is prepared.

Then, the red electrophoretic particle dispersion (1) is prepared by mixing the white electrophoretic particle dispersion (1) prepared in Example 2 with the red electrophoretic particle dispersion (1).

Example  4: Preparation of Red Electrophoretic Particle Dispersion (2) and Suspension (2)

Prepared in the same manner as in Example 3, to increase the amount of negative charge control agent to 2 times as in Example 3 to prepare a red electrophoretic particle dispersion (2).

Then, the red electrophoretic particle dispersion 2 was prepared by mixing the white electrophoretic particle dispersion prepared in Example 2 with the red electrophoretic particle dispersion 2.

Example  5: Preparation of green electrophoretic particle dispersions (1) and suspensions (1)

Dissolve 10 g of a binder resin using a binder containing 1% by weight of a polar group in the main chain and side chain in 100 g of ethyl acetate solvent, 3 g of green pigment (organic pigment: Green 58), 3 g of negative charge charge regulator, and 100 g of 0.3-3 mm size of zirconia ball. Including 1 ~ 5000g 2 hours ~ 48 hours dispersion using a disperser. It is then subjected to secondary dispersion with 3 g of negative charge control agent under the same conditions. Remove the ball from the secondary dispersion by using a diluent (ethyl acetate, 10% by weight of anti-flocculation agent), and then in the reactor using a low viscosity disperser in the range of 20 ℃ ~ 80 ℃, 1 ~ 30 minutes under 100 ~ 5000 RPM conditions While the particles are dispersed at high speed in an isoparaffinic solvent. Accordingly, a green electrophoretic particle dispersion 1 having a uniform size and having negatively charged green electrophoretic particles is prepared.

Then, the white electrophoretic particle dispersion (1) prepared in Example 2 and the green electrophoretic particle dispersion (1) were mixed to prepare a green electrophoretic particle suspension (1).

Example  6: Preparation of green electrophoretic particle dispersions (2) and suspensions (2)

Prepared in the same manner as in Example 5, to increase the amount of negative charge control agent to twice the Example 5 to prepare a green electrophoretic particle dispersion (2).

Then, the blue electrophoretic particle dispersion (2) prepared in Example 2 was mixed with the green electrophoretic particle dispersion (2) to prepare a blue electrophoretic particle suspension (2).

Example  7: Preparation of blue electrophoretic particle dispersion (1) and suspension (1)

Dissolve 10 g of binder resin using a binder containing 1% by weight of a polar group in the main chain and side chain in 100 g of ethyl acetate solvent, 3 g of blue pigment (organic pigment: Blue 15: 6), 3 g of negative charge charge regulator and 0.3-3 mm size of zirconia ball. Including 100g ~ 5000g of 2 hours to 48 hours dispersion using a disperser. It is then subjected to secondary dispersion with 3 g of negative charge control agent under the same conditions. Remove the ball from the secondary dispersion by using a diluent (ethyl acetate, 10% by weight of anti-flocculation agent), and then in the reactor using a low viscosity disperser in the range of 20 ℃ ~ 80 ℃, 1 ~ 30 minutes under 100 ~ 5000 RPM conditions While the particles are dispersed at high speed in an isoparaffinic solvent. Accordingly, a blue electrophoretic particle dispersion 1 in which blue electrophoretic particles having a uniform size and having negative charges are dispersed is prepared.

Then, the blue electrophoretic particle dispersion (1) prepared in Example 2 was mixed with the blue electrophoretic particle dispersion (1) to prepare a blue electrophoretic particle suspension (1).

Example  8: Preparation of blue electrophoretic particle dispersions (2) and suspensions (2)

Prepared in the same manner as in Example 7, and the blue electrophoretic particle dispersion (2) was prepared by increasing the amount of the negative charge control agent to twice that of Example 7.

Then, the blue electrophoretic particle dispersion (2) prepared in Example 2 was mixed with the blue electrophoretic particle dispersion (2) to prepare a blue electrophoretic particle suspension (2).

Comparative example  1: Preparation of Red Electrophoretic Particle Dispersions and Suspensions

10 g of a binder resin using a binder containing 1% by weight of a polar group in the main chain and side chain was dissolved in 100 g of ethyl acetate solvent, 0.3 g of a white pigment (titanium oxide), a red pigment (organic pigment: Red 354), and 3 g of a negative charge charge control agent. Zirconia ball 0.3 ~ 3mm size 100g ~ 5000g including 2 hours to 48 hours dispersion using a disperser. It is then subjected to secondary dispersion with 3 g of negative charge control agent under the same conditions. Remove the ball from the secondary dispersion by using a diluent (ethyl acetate, 10% by weight of anti-flocculation agent), and then in the reactor using a low viscosity disperser in the range of 20 ℃ ~ 80 ℃, 1 ~ 30 minutes under 100 ~ 5000 RPM conditions While mixing, and dispersing the particles in a isoparaffinic solvent at high speed to prepare a red electrophoretic particle dispersion in which negatively charged red electrophoretic particles are dispersed.

Thereafter, the white electrophoretic particle dispersion prepared in Example 2 and the red electrophoretic particle dispersion were mixed to prepare a red electrophoretic particle suspension.

Comparative example  2: Preparation of Green Electrophoretic Particle Dispersions and Suspensions

Dissolve 10 g of a binder resin using a binder containing 1% by weight of a polar group in the main chain and side chain in 100 g of ethyl acetate solvent, 0.3 g of a white pigment (titanium oxide), a green pigment (organic pigment: Green 58), and 3 g of a negative charge charge regulator. Zirconia ball 0.3 ~ 3mm size 100g ~ 5000g including 2 hours to 48 hours dispersion using a disperser. It is then subjected to secondary dispersion with 3 g of negative charge control agent under the same conditions. Remove the ball from the secondary dispersion by using a diluent (ethyl acetate, 10% by weight of anti-flocculation agent), and then in the reactor using a low viscosity disperser in the range of 20 ℃ ~ 80 ℃, 1 ~ 30 minutes under 100 ~ 5000 RPM conditions While mixing, and dispersing the particles at high speed in an isoparaffinic solvent to prepare a green electrophoretic particle dispersion in which negatively charged green electrophoretic particles are dispersed.

Then, the white electrophoretic particle dispersion prepared in Example 2 and the green electrophoretic particle dispersion were mixed to prepare a green electrophoretic particle suspension.

Comparative example  3: Preparation of Blue Electrophoretic Particle Dispersions and Suspensions

Dissolve 10 g of a binder resin using a binder containing 1% by weight of a polar group in the main chain and side chain in 100 g of ethyl acetate solvent, 0.3 g of a white pigment (titanium oxide), a blue pigment (organic pigment: Blue 15: 6), and a negative charge charge control agent. 3g and zirconia ball 0.3g-3mm size 100g ~ 5000g, including 2 hours to 48 hours dispersion using a disperser. It is then subjected to secondary dispersion with 3 g of negative charge control agent under the same conditions. Remove the ball from the secondary dispersion by using a diluent (ethyl acetate, 10% by weight of anti-flocculation agent), and then in the reactor using a low viscosity disperser in the range of 20 ℃ ~ 80 ℃, 1 ~ 30 minutes under 100 ~ 5000 RPM conditions While mixing and dispersing the particles in a isoparaffinic solvent at high speed to prepare a blue electrophoretic particle dispersion in which negatively charged blue electrophoretic particles are dispersed.

Then, the white electrophoretic particle dispersion prepared in Example 2 and the blue electrophoretic particle dispersion were mixed to prepare a blue electrophoretic particle suspension.

Image stability and Color characteristics  Measurement result

The black electrophoretic particle dispersion prepared in Example 1 and the red electrophoretic particle suspension (1) prepared in Example 3 or the red electrophoretic particle suspension (2) prepared in Example 4 were prepared using an insulating solvent (iso). Paraffin solvent and halocarbon solvent) were mixed and stirred to prepare a red ink of the example. The black electrophoretic particle dispersion prepared in Example 1 and the green electrophoretic particle suspension (1) prepared in Example 5 or the green electrophoretic particle suspension (2) prepared in Example 6 were prepared using an insulating solvent (iso). Paraffin solvent and halocarbon solvent) were mixed and stirred to prepare the green ink of the example. The black electrophoretic particle dispersion prepared in Example 1 and the blue electrophoretic particle suspension (1) prepared in Example 7 or the blue electrophoretic particle suspension (2) prepared in Example 8 were used as an insulating solvent (iso). Paraffin solvent and halocarbon solvent) were mixed and stirred to prepare a blue ink of the example.

The black electrophoretic particle dispersion prepared in Example 1 and the red, green, and blue electrophoretic particle suspension prepared in Comparative Examples 1 to 3 were mixed and stirred with an insulating solvent (isoparaffinic solvent and halocarbon solvent). The red, green, and blue inks of the comparative examples were prepared.

The red, green, blue, and white inks prepared in the above Examples and Comparative Examples were injected into the gap (35 μm) between the upper and lower glass substrates (2 cm × 2 cm) having a partition (within 35 μm) formed thereon and coated with an ITO electrode. , Driving the driving voltage of 15V, the color reproducibility, the light reflectance and the pair safety measurement results are shown in Table 1 to Table 3.

Referring to Table 1, when using the red electrophoretic particles prepared by adjusting the content of the charge control agent in Examples 3 and 4 of the present invention, compared to the case of using the red electrophoretic particles of Comparative Example 1, Coordinate value (Rx) is 0.5 or more, red color reproduction rate is high, contrast ratio is 10: 1 or more, high reflectance is high, and bistable stability, which is a measure of image stability, is excellent at 2.5 or less in both color state and black state. It can be seen.

Referring to Table 2, in the case of using the green electrophoretic particles prepared by adjusting the content of the charge control agent in Examples 5 and 6 of the present invention, compared to the case of using the green electrophoretic particles of Comparative Example 2, It can be seen that the coordinate value Gy is 0.4 or more, the green color reproduction rate is high, the contrast ratio is 10: 1 or more, and the reflectance is high, and the bistable stability is excellent in the color state and the black state, respectively, 2.5 or less. .

Referring to Table 3, when using the blue electrophoretic particles prepared by adjusting the content of the charge control agent in Examples 7 and 8 of the present invention, compared to the case of using the blue electrophoretic particles of Comparative Example 3, It can be seen that the coordinate value (Bx) is 0.16 or less, the blue color reproducibility is high, the contrast ratio is 8: 1 or more, and the reflectance is good. In addition, the bistable stability is excellent at 2.5 or less in both color and black states. .

The Example  According to panel manufacturing

The black electrophoretic particle dispersion prepared in Example 1 and the white electrophoretic particle dispersion prepared in Example 2 were mixed and stirred with an insulating solvent (isoparaffin solvent and halocarbon solvent) to prepare a white ink. The black electrophoretic particle dispersion prepared in Example 1 and the red electrophoretic particle suspension (1) prepared in Example 3 or the red electrophoretic particle suspension (2) prepared in Example 4 were prepared using an insulating solvent (iso). Paraffin solvent and halocarbon solvent) are mixed and stirred to prepare a red ink. The black electrophoretic particle dispersion prepared in Example 1 and the green electrophoretic particle suspension (1) prepared in Example 5 or the green electrophoretic particle suspension (2) prepared in Example 6 were prepared using an insulating solvent (iso). Paraffin solvent and halocarbon solvent) to stir and prepare a green ink. The black electrophoretic particle dispersion prepared in Example 1 and the blue electrophoretic particle suspension (1) prepared in Example 7 or the blue electrophoretic particle suspension (2) prepared in Example 8 were used as an insulating solvent (iso). Paraffin solvent and halocarbon solvent) to stir and prepare a blue ink. The color particle suspension includes 1 to 50 parts by weight of the color particle dispersion relative to the white particle dispersion. The color particle suspension includes 1 to 50 parts by weight of the black particle dispersion relative to the white particle dispersion. The size of the pigment nucleus in the color particles is 30-400 nm.

As shown in FIG. 2, an electrophoretic display device in which white, red, green, and blue inks are injected into each of the white, red, green, and blue pixels W, R, G, and B is manufactured.

The electrophoretic display device illustrated in FIG. 2 is formed between a lower substrate 1 on which the first electrode 7 is formed, an upper substrate 2 on which the second electrode 8 is formed, and an upper and lower substrates 1 and 2. White, red, green, blue pixels W, in which white, red, green, and blue inks are injected into the pixel spaces formed by the barrier ribs 3 of the matrix structure, the upper and lower substrates 1, 2, and the barrier ribs 3, respectively. R, G, and B).

A glass substrate is mainly used as the lower substrate 1, and a polyethylene terephthalate (PET) film is used as the upper substrate 2. The first electrode 7 of each sub-pixel is formed on the lower substrate 1, and the partition walls of the matrix structure are formed on the lower substrate 1 by using negative photoresist, whereby white, red, green, and blue pixels (W, R, G) are formed. , B) is provided. In each pixel space, red, green, blue and white inks are respectively injected using a screen printing method. After printing white ink on the white pixel W, the solvent is dried, and then red ink is printed on the red pixel R and then dried, and the green pixel G and the blue pixel B are printed by the same printing method. Green ink and blue ink are printed sequentially. After the four-color ink is printed on the white, red, green, and blue pixels (W, R, G, and B), the isoparaffinic solvent is re-injected and dried on each pixel (W, R, G, and B). Redispersion of white, red, green, blue, and black electrophoretic particles (5W, 5R, 5G, 5B, 6) is performed. The lower substrate 1 on which the white, red, green, and blue pixels W, R, G, and B are formed, and the upper substrate 2 on which the second electrode 8 is formed are bonded and sealed to display color electrophoresis. Manufacture the device.

As the printing method of the ink containing the electrophoretic particles, one of screen printing, gravure printing, offset printing, and flexographic printing is used.

Referring to FIG. 2, when the electric field is applied, the white, red, green, and blue electrophoretic particles 5W, 5R, 5G, and 5B have a negative charge, and the black electrophoretic particles 6 are positive. ) Has a charge. The white, red, green, and blue electrophoretic particles 5W, 5R, 5G, and 5B having negative (-) have sizes of 30 to 500 nanometers, and the black electrophoretic particles (6) having positive (+) have It has a size of 500-1500 nanometers.

The white pixel W includes the white electrophoretic particles 5W and the black electrophoretic particles 6 mixed in the solvent 4 of the electrophoretic medium. In response to the voltages applied to the first and second electrodes 7 and 8, the white pixel W moves white when the white electrophoretic particles 5W move toward the upper substrate 2, and black electrophoretic particles 6. Is moved toward the upper substrate 2, and black is displayed.

The red pixel R includes red electrophoretic particles 5R, white electrophoretic particles 5W, and black electrophoretic particles 6 mixed in the solvent 4 of the electrophoretic medium. The red pixel R is red when the red electrophoretic particles 5R and the white electrophoretic particles 5W move toward the upper substrate 2 in response to voltages applied to the first and second electrodes 7 and 8. When black electrophoretic particles 6 move toward the upper substrate 2, black is displayed. On the other hand, the white electrophoretic particles 5W have a specific gravity 4 greater than the specific gravity (1-2) of the red electrophoretic particles 5R, and thus the white electrophoretic particles under the red electrophoretic particles 5R on the upper and lower sides, respectively. 5W is disposed.

The green pixel G comprises green electrophoretic particles 5G and black electrophoretic particles 6 mixed in a solvent 4 of an electrophoretic medium. In response to voltages applied to the first and second electrodes 7 and 8, the green pixel G moves green when the black electrophoretic particles 5G move toward the upper substrate 2, and the black electrophoretic particles 6. Is moved toward the upper substrate 2, and black is displayed. On the other hand, the white electrophoretic particles 5W have a specific gravity 4 greater than the specific gravity (1-2) of the green electrophoretic particles 5G, so that the white electrophoretic particles below the green electrophoretic particles 5G on the upper and lower sides, respectively. 5W is disposed.

The blue pixel B includes the blue electrophoretic particles 5B and the black electrophoretic particles 6 mixed in the solvent 4 of the electrophoretic medium. In response to voltages applied to the first and second electrodes 7 and 8, the blue pixel B may move blue toward the upper substrate 2 when the blue electrophoretic particles 5B move toward the upper substrate 2, and black electrophoretic particles 6. Is moved toward the upper substrate 2, and black is displayed. On the other hand, the white electrophoretic particles 5W have a specific gravity 4 greater than the specific gravity (1-2) of the blue electrophoretic particles 5G, so that the white electrophoretic particles below the blue electrophoretic particles 5B on the upper and lower sides, respectively. 5W is disposed.

As described above, in the present invention, white electrophoretic particles and color electrophoretic particles having white and colored pigments as nuclei are prepared, respectively. By forming the color electrophoretic particles into particles separate from the white electrophoretic particles, color electrophoretic particles can be produced simply and easily, and color electrophoretic particles can be prepared by changing the type and content of the dispersion by introducing a color pigment dispersion. By controlling the size and the amount of charge separately, it is possible to improve color reproducibility and reflectance and to secure excellent bistable stability.

1: lower substrate 2: upper substrate
3: bulkhead 4: electrophoretic medium
5W: white electrophoretic particles 5R: red electrophoretic particles
5G: Green Electrophoretic Particles 5B: Blue Electrophoretic Particles
6: black electrophoretic particle 7: first electrode
8: second electrode 10: colored electrophoretic particles
12: color pigment 14: polymer resin
16: charge control agent 18: surfactant

Claims (21)

A core portion consisting of colored pigments;
Color electrophoretic particles, characterized in that it comprises a shell portion surrounding the curl pigment consisting of a binder comprising a charge control agent. The method according to claim 1,
The color pigments are zinc oxide, titanium oxide, titanium bag, CIPigment RED254, CIPigment RED177, CIPigment RED122, CIPigment YELLOW139, CIPigment BLUE15: 1, CIPigment BLUE15: 3 CIPigment BLUE15: 4, CIPigment BLUE15: 6, CIPigment VIOLET23, CIPigment GREEN36, CIPigment YELLOW138, CIPigment YELLOW139, CIPigment YELLOW150 color electrophoretic particles, characterized in that at least one selected. The method according to claim 2,
The binder is colored electrophoretic particles, characterized in that at least one selected from polyester-based, polyacrylate-based, polyurethane-based. The method according to claim 1,
The size of the color electrophoretic particles are color electrophoretic particles, characterized in that 30 ~ 500nm. A plurality of pixels injected with color electrophoretic ink in which a plurality of electrophoretic particles having different polarities are dispersed in an insulating fluid in a suspended state;
The electrophoretic particle comprises a color electrophoretic particle according to any one of claims 1 to 4, characterized in that the color electrophoretic display device. The method according to claim 5,
The plurality of pixels comprises white, red, green, blue pixels;
White ink including white electrophoretic particles and black electrophoretic particles is injected into the white pixel,
Red ink including red electrophoretic particles, white electrophoretic particles, and black electrophoretic particles is injected into the red pixel,
The green pixel is injected with green ink including green electrophoretic particles, white electrophoretic particles, and black electrophoretic particles,
And a blue ink including blue electrophoretic particles, white electrophoretic particles, and black electrophoretic particles. The method of claim 6,
Each of the red, green, and blue electrophoretic particles has a specific gravity smaller than that of the white electrophoretic particles. The method of claim 6,
Each of the white, red, green, and blue electrophoretic particles includes a negative charge control agent, and the black electrophoretic particles include a positive charge control agent. The color pigment is dispersed in a dispersant, a binder, and an organic solvent to prepare a color electrophoretic particle dispersion in which color electrophoretic particles having a core portion of the color pigment and a shell portion of the binder are dispersed in the dispersant and the organic solvent. Color electrophoretic particle dispersion production method comprising the step of. The method according to claim 9,
The colored pigment is an organic pigment, an inorganic pigment, or an organic-inorganic salt with zinc oxide, titanium oxide, titanium bag, CIPigment RED254, CIPigment RED177, CIPigment RED122, CIPigment YELLOW139, CIPigment BLUE15: 1, CIPigment BLUE15: 3 CIPigment BLUE15: 4, CIPigment BLUE15: 6, CIPigment VIOLET23, CIPigment GREEN36, CIPigment YELLOW138, CIPigment YELLOW139, CIPigment YELLOW150 characterized in that at least one selected from the color electrophoretic particle dispersion production method. The method according to claim 9,
The organic solvent is propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol mono acetone methyl ethyl ketone cyclonucleosanone ethanol methylene chloride ethyl ether acetate, propylene glycol monoethyl ether, ethoxypropionic acid, xylene, toluene, butyl Method for producing a color electrophoretic particle dispersion, characterized in that at least one selected from acetate, butanol. The method of claim 11,
The organic solvent is a color electrophoretic particle dispersion manufacturing method comprising 10 to 90 parts by weight. The method according to claim 9,
The dispersant and the binder is a color electrophoretic particle dispersion production method, characterized in that at least one selected from polyester, polyacrylate, polyurethane-based. The method according to claim 9,
The dispersant and the binder is a color electrophoretic particle dispersion production method comprising 5 to 80 parts by weight. The method according to claim 9,
The size of the color electrophoretic particles is a color electrophoretic particle dispersion production method, characterized in that 30 ~ 500nm. The method according to claim 9,
The color pigment is a color electrophoretic particle dispersion manufacturing method characterized in that it comprises 1 to 10 parts by weight. Preparing a black electrophoretic particle dispersion and a white electrophoretic particle dispersion;
Preparing a color electrophoretic particle dispersion according to any one of claims 9 to 16;
Preparing a color electrophoretic particle suspension by mixing the white electrophoretic particle dispersion and the color electrophoretic particle dispersion;
Preparing a white ink by mixing the black electrophoretic particle dispersion and the white electrophoretic particle dispersion;
Preparing a color ink by mixing the black electrophoretic particle dispersion and the color electrophoretic particle suspension;
Forming a partition on the first substrate on which the first electrode is formed to provide each pixel space;
Injecting the white, red, green, and blue inks into the pixel spaces, respectively;
And bonding and sealing a second substrate having a second electrode formed thereon on the first substrate to which the ink is injected. 18. The method of claim 17,
Wherein each of the white, red, green, and blue electrophoretic particles includes a negative charge control agent, and the black electrophoretic particles include a positive charge control agent. The method according to claim 17
The color particle suspension is a method of manufacturing a color electrophoretic display device, characterized in that containing 1 to 50 parts by weight of the color particle dispersion relative to the white particle dispersion. The method according to claim 17
The color particle suspension is a method of manufacturing a color electrophoretic display device, characterized in that the black particle dispersion compared to the white particle dispersion comprises 1 to 50 parts by weight. The method according to claim 17
The size of the pigment nucleus in the color particles is a method of manufacturing a color electrophoretic display device, characterized in that 30 ~ 400nm.

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