JPH09318977A - Liquid crystal microcapsule and liquid crystal display device using the same - Google Patents

Abstract

(57) Abstract: A liquid crystal microcapsule having a property of continuously changing a hue, and a liquid crystal display having a simple structure, excellent color display characteristics, and low cost. The purpose is to provide a device. A liquid crystal display device having a liquid crystal layer sandwiched between a pair of substrates, wherein the liquid crystal layer colors dichroic dye molecules and liquid crystal molecules in a hue different from the hue of the dichroic dye molecules. It is characterized in that it includes a liquid crystal microcapsule formed by encapsulating the polymer material.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid crystal microcapsule and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art Guest-host type liquid crystal display elements, in which a dye having a large dichroic ratio is dissolved in liquid crystal, have advantages such as a wide viewing angle and are one of the display elements expected in the future. Is. In recent years, demand for color displays has increased, and guest-host color displays have been actively developed. An example of this is (T.
Utida: Proc. 3rd. Display Res. Conf., P202, 1983), a liquid crystal display device in which guest-host cells of three colors of yellow, cyan and magenta are laminated is mentioned.

However, in this liquid crystal display device, 3
Various problems arise due to the superposition of two guest-host cells. First, since the cell assembling process is complicated and difficult, the yield is reduced and the manufacturing cost is increased. Further, as display characteristics, parallax occurs due to superposition, which limits the viewing angle. Furthermore, since the number of transparent electrodes and alignment films is three times that of a normal single-layer cell, the transmittance is reduced.

Many studies have been made to solve these problems, such as simplifying the assembly process, improving the transparency of transparent electrodes and alignment films, and thinning the glass substrate sandwiching the liquid crystal layer. The current situation is that satisfactory characteristics have not yet been obtained.

Further, as another display device using the guest-host system, a cholesteric-nematic phase transition of a liquid crystal layer containing a black dichroic dye is used as a light valve, and green and magenta are used for color display. SID 92 DIGEST P437. S. Mit using a color filter consisting of
sui et. al. However, with this display element, a bright and clear display cannot be obtained, the color display range is limited, and sufficient characteristics as a display element cannot be obtained. In addition, in the method using a color filter, since white display is obtained by additive color mixing of the colors of the color filter, the transmitted light intensity becomes one third or less, and thus the display capability is limited.

A liquid crystal microcapsule obtained by encapsulating a liquid crystal molecule and a dichroic dye molecule in a polymer material is used in a liquid crystal layer of a liquid crystal display element. The liquid crystal microcapsule has a hue changeable. Therefore, it is not possible to realize a liquid crystal display device capable of producing fine gradation.

The present invention has been made in view of the above points, and liquid crystal microcapsules having a property of continuously changing hue, and a simple structure, excellent color display characteristics, and low cost. It is an object of the present invention to provide a liquid crystal display device that is

[0008]

The present invention provides a liquid crystal microcapsule obtained by encapsulating a dichroic dye molecule and a liquid crystal molecule in a polymer material, wherein the polymer material is a hue of the dichroic dye molecule. A liquid crystal microcapsule characterized by being colored in a different hue.

Further, the present invention is a liquid crystal display device having a liquid crystal layer sandwiched between a pair of substrates, wherein the liquid crystal layer is
A liquid crystal display device comprising a liquid crystal microcapsule obtained by encapsulating a dichroic dye molecule and a liquid crystal molecule with a polymer material colored in a hue different from the hue of the dichroic dye molecule.

In the liquid crystal display device of the present invention, the liquid crystal layer has a region containing liquid crystal microcapsules in which liquid crystal molecules and yellow dichroic dye molecules are encapsulated by a polymer material colored in blue, and liquid crystal molecules. And a region containing liquid crystal microcapsules in which cyan dichroic dye molecules are encapsulated in a red colored polymeric material,
It is preferable that the liquid crystal molecules and a region containing liquid crystal microcapsules in which magenta dichroic dye molecules are encapsulated with a polymer material colored in green are arranged side by side. In the above, the hue of the colored liquid crystal and the hue of the colored polymer material may be reversed.

The liquid crystal layer includes a region including liquid crystal microcapsules in which liquid crystal molecules and black dichroic dye molecules are encapsulated by a polymer material colored in blue, and a dichroic property of the liquid crystal molecules and black. A region containing a liquid crystal microcapsule in which a dye molecule is encapsulated in a polymer material colored red, and a liquid crystal molecule and a black dichroic dye molecule are encapsulated in a polymer material colored green It is preferable that the regions including the liquid crystal microcapsules are arranged side by side.

In the liquid crystal display device of the present invention, it is preferable that the color of the dichroic dye molecules in the liquid crystal microcapsules and the color of the colored polymer material have a complementary color relationship.
Further, in the liquid crystal display element of the present invention, it is preferable to further provide a transmission / scattering layer on the liquid crystal layer.

[0013]

Embodiments of the present invention will be specifically described below with reference to the drawings. The liquid crystal microcapsule of the present invention is characterized by encapsulating a dichroic dye molecule and a liquid crystal molecule with a polymer material, and the polymer material is colored in a hue different from the hue of the dichroic dye molecule. . The liquid crystal microcapsules are capable of continuously changing the hue depending on the magnitude of the applied voltage. Therefore, the hue can be freely adjusted by controlling the applied voltage.

Further, in the liquid crystal display device using the liquid crystal microcapsules of the present invention, since the display areas of the respective colors can be arranged side by side, the structure can be simplified. Further, the liquid crystal microcapsules continuously change the hue depending on the magnitude of the applied voltage, and thus exhibit excellent color display characteristics.

As shown in FIG. 1, the liquid crystal microcapsule of the present invention has a structure in which a dichroic dye molecule 1 and a liquid crystal molecule 2 are microencapsulated with a polymer material 3 containing an isotropic dye molecule 4, That is, in the polymer outer wall made of a polymer material colored in a predetermined color with an isotropic dye,
It has a structure in which a liquid crystal phase in which a dichroic dye is dissolved is present. Although the isotropic dye molecule 4 is used here, the dye molecule does not have to be isotropic.

The liquid crystal microcapsules have a property that the hue continuously changes as a voltage is applied. For example, when the polymer outer wall is colored blue with a blue isotropic dye and a yellow dichroic dye is used, yellow and blue are subtractively mixed when no voltage is applied, and the display is black. As the voltage is applied, the dye molecules rise and yellow becomes weaker, and the hue continuously approaches blue. Similarly, when the outer wall of the polymer is colored green with a green isotropic dye and a magenta dichroic dye is used, magenta becomes weaker because the dye molecule rises as a voltage is applied, and the hue is continuous. Approaching the green. Similarly, when the polymer outer wall is colored red using a red isotropic dye and cyan dichroic dye is used, cyan weakens because the dye molecules rise as voltage is applied, and the hue is continuous. Approaching red. The liquid crystal may be colored black in consideration of the reduction of the reflectance during black display.

Considering the contrast of the display element, a p-type dichroic dye is used and a p-type liquid crystal is used.
It is preferable to use a mold. When the liquid crystal phase is colored blue, magenta and cyan dichroic dyes are mixed, and when the liquid crystal phase is colored red, magenta and yellow dichroic dyes are mixed, and the liquid crystal phase is mixed. When is colored green, dichroic dyes of yellow and cyan are mixed.

Here, as the yellow dichroic dye,
For example, G-232 made by Nihon Senshoku Co., Ltd., SI by Aussie
-209, M-361, etc. can be used. Examples of cyan dichroic dyes include SI-501 and S manufactured by Aussie.
I-497, M-403, G-472 manufactured by Japan Photosensitizing Co., Ltd.
Etc. can be used. Examples of magenta dichroic dyes include G-239, G-471, and G-2 manufactured by Japan Photosensitive Dye Company.
02, Aussie SI-512, M-618, M-3
70 or the like can be used.

Further, as liquid crystal materials, TC-4368XX, ZLI-4281 / 2, ZL manufactured by Merck Japan Co., Ltd.
I-3889, ZLI-5500-000, MLC-6
041-000, ZLI-4620, ZLI-5100
-000, ZLI-1840, ZLI-2116-00
0, LIXON4033-000X manufactured by Chisso Chemical Co., Ltd.
X, LIXON 4034-000XX, ZLI-229
3 or the like can be used.

Further, as the monomer of the polymer material, methyl methacrylate, isobutyl methacrylate, t-
Butyl methacrylate or the like can be used. The thickness of the polymer material, that is, the thickness of the outer wall of the liquid crystal microcapsule is preferably 3 μm or less in consideration of the light absorption efficiency of the colored layer.

As the isotropic dye (colorant for the polymer on the outer wall) added to the polymer material, dyes, pigments and the like can be used. For example, as the dye, Solvent Red 109, Solvent Red 100, Solvent Red 82, Solvent Red 27, Solvent Red 23, Solvent Blue 11, Solvent Blue 11
1, Solvent Blue 12, Solvent Blue 44, Solvent Yellow 2, Solvent Yellow 14, Solvent Yellow 61, Solvent Yellow 82, Solvent Green 3, and the like. As a pigment,
C. I. Pigment Red 97, C.I. I. Pigment Red 122, C.I. I. Pigment Red 149,
C. I. Pigment Red 168, C.I. I. Pigment Red 177, C.I. I. Pigment Red 18
0, C.I. I. Pigment Red 192, C.I. I. Pigment Red 215, C.I. I. Pigment Green 7, C.I. I. Pigment Green 36, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 4, Pigment Blue 15: 6, C.I. I. Pigment Blue 22, C.I. I. Pigment Blue 6
0, C.I. I. Pigment Blue 64 and the like.

When a pigment is used, the particle diameter of the pigment is 1 μm or less, more preferably 0.2 μm, in order to avoid scattering of visible light and disturbance of the liquid crystal phase due to unevenness at the interface between the liquid crystal and the polymer material. The following is desirable.

In the present invention, the production method of liquid crystal microcapsules may be a reverse phase micelle polymerization method, an emulsion polymerization method, a soapy polymerization method, a non-aqueous dispersion polymerization method, a suspension polymerization method, a swelling polymerization method or the like. Not limited to.

When the liquid crystal microcapsule of the present invention is used in a liquid crystal display device, the liquid crystal layer can be formed or patterned by a method such as a printing method or a coating method. Since the liquid crystal microcapsule of the present invention can be patterned, the liquid crystal layer can be formed in a juxtaposed arrangement as shown in FIG.

FIG. 3 is a sectional view showing an example of a liquid crystal display element using the liquid crystal microcapsule of the present invention. 11 in the figure
Indicates a glass substrate. A transparent electrode film 12 made of ITO (Indium Tin 1Oxide) or the like is provided on one surface of the glass substrate 11. A liquid crystal layer 13 is arranged between a pair of glass substrates 11 arranged so that the transparent electrode films 12 face each other. The liquid crystal layer 13 includes a liquid crystal microcapsule region 17 including liquid crystal microcapsules 14 that change black / red, a liquid crystal microcapsule region 18 including liquid crystal microcapsules 15 that changes black / green, and a black / blue change. And a liquid crystal microcapsule region 19 composed of liquid crystal microcapsules 16 for This liquid crystal display element can display black and color with one pixel according to changes in the liquid crystal microcapsules. Therefore, the contrast is large and the color display characteristics are excellent.

FIG. 4 is a cross-sectional view showing another example of a liquid crystal display device using the liquid crystal microcapsule of the present invention. This liquid crystal display element has a structure in which a transmission / scattering layer 20 is laminated on the liquid crystal display element shown in FIG. This transmission
As the scattering layer 20, a polymer dispersed liquid crystal display device (PDLC) in which liquid crystal regions are scattered in a polymer matrix can be used.

Further, as shown in FIG. 5, the transmission / scattering layer 20 is directly provided on the liquid crystal layer 13 and sandwiched between the pair of glass substrates 11, and the liquid crystal and the liquid crystal layer in the transmission / scattering layer 20 are arranged. The threshold voltage of the liquid crystal in 13 may be set to be different, and the pair of transparent electrode films 12 may drive the liquid crystal display element. In this case, bright display can be obtained with a simple configuration.

With the structure shown in FIGS. 4 and 5, the scattering intensity can be adjusted by the transmission / scattering layer (upper layer) 20. As a result, as shown in Table 1 below, a fine gradation can be produced in the brightness of the display color, and a fine color tone can be produced in the color display.

[0029]

[Table 1]

Next, examples carried out to clarify the effects of the present invention will be described. (Example 1) TC- manufactured by Merck Japan Co., which is a liquid crystal material
A cyan dichroic dye SI-497 manufactured by Aussie Co. was dissolved in 4368XX in a proportion of 2% by weight to prepare a liquid crystal material colored in cyan. This colored liquid crystal material was microencapsulated with vinylbenzene colored with Solvent Red 109 by a soapy polymerization method to prepare liquid crystal microcapsules. In the soapy polymerization method, the stirring rate, polymerization rate, etc. of the reaction solution were adjusted so that the average particle size of the microcapsules was 2 μm. The liquid crystal microcapsules were sandwiched between a pair of glass substrates provided with transparent electrode films, and a voltage was gradually applied to examine the change in hue. As a result, the liquid crystal microcapsules that were initially black showed a hue of 10 V at the red direction. Begins to change, 12V
Became completely red and no longer changed.

In addition, the liquid crystal material TC-4368XX manufactured by Merck Japan Co., Ltd. was dissolved with magenta dichroic dye G-239 manufactured by Japan Photosensitive Dyestuff Co. at a ratio of 1.5 wt%. A liquid crystal material was prepared. This colored liquid crystal material was microencapsulated with vinylbenzene colored with Solvent Green 3 by the soapy polymerization method in the same manner as described above to prepare liquid crystal microcapsules. The liquid crystal microcapsules were sandwiched between a pair of glass substrates provided with transparent electrode films, and a voltage was gradually applied to examine the change in hue. As a result, the liquid crystal microcapsules that were initially black showed a hue of 10 V at the green color. It started to change, became completely green at 12V, and stopped changing any more.

Further, a yellow dichroic dye G-232 made by Japan Photosensitive Dyes Co., Ltd. was dissolved in TC-4368XX made by Merck Japan Co., Ltd. which is a liquid crystal material at a ratio of 2.1% by weight to give a yellow color. A liquid crystal material was prepared. This colored liquid crystal material was microencapsulated with vinyl benzene colored with Solvent Blue 44 by the soapy polymerization method in the same manner as described above to prepare liquid crystal microcapsules. The liquid crystal microcapsules were sandwiched between a pair of glass substrates provided with transparent electrode films, and a voltage was gradually applied to examine the change in hue. As a result, the initially black liquid crystal microcapsules showed a hue in the blue direction at 10V. It started to change, turned completely blue at 12V, and stopped changing any further.

Liquid crystal layers were formed by printing these three kinds of liquid crystal microcapsules on the other surface of a glass substrate having a reflective electrode on one surface in a pattern as shown in FIG. During printing, a small amount of spacers were mixed with the liquid crystal microcapsules. Next, a glass substrate (counter substrate) having a transparent electrode film made of ITO on one surface is
Two glass substrates were bonded together so that the transparent electrode film faced the liquid crystal layer and air was not allowed to enter. Thus, the liquid crystal display device of the present invention was manufactured.

Regarding the obtained liquid crystal display element, white display,
When the black display and the color display were examined, the reflectance at white display was 2
The reflectance was 0%, and the reflectance when displaying black was 1%. As described above, the liquid crystal display element of the present embodiment has an extremely simple structure and can easily have a large screen, and has a color display capability equivalent to that of a conventional liquid crystal display element using a color filter. (Example 2) A glass substrate having a transparent electrode film made of ITO formed on both surfaces as a glass substrate which is a counter substrate in Example 1 and further provided with a transparent electrode film made of ITO on one surface Were placed so that the transparent electrode films face each other, and were bonded so that the cell gap was 10 μm. Next, a liquid mixture containing a polyurethane monomer and a liquid crystal material is injected between the glass substrates, and the monomers are polymerized to form PDLC as a transmission / scattering layer.
A layer was formed. Thus, the liquid crystal display element of the present invention as shown in FIG. 4 was produced.

Regarding the obtained liquid crystal display element, white display,
When the black display and the color display were examined, the reflectance at white display was 6
The reflectance was 5%, and the reflectance when displaying black was 3%. Also,
In the color display, a clear color display could be realized due to the two-layer structure. Further, in this case, since the transmission / scattering layer is present in the color display, a fine gradation can be produced in the brightness of the display color, and a fine color tone can be produced in the color display. (Example 3) In the same manner as in Example 1, three types of liquid crystal microcapsules were printed on the other surface of a glass substrate having a reflective electrode on one surface in a pattern as shown in FIG. Was formed. Next, a glass substrate provided with a transparent electrode film made of ITO on one surface was placed so that the transparent electrode films face each other, and the cell gap was 10 μm.
Then, the PDLC layer was formed as a transmission / scattering layer in the same manner as in Example 2 by adhering so as to obtain m. In addition, PDLC
Had a threshold voltage of 8V. Thus, the liquid crystal display element of the present invention as shown in FIG. 5 was produced. When a voltage is gradually applied to this liquid crystal display element, it is 8
If it is less than V, white display can be obtained, if it is 8 to 10 V, black display can be obtained, and if it is 10 V or more, color display can be obtained.

Regarding the obtained liquid crystal display element, white display,
When the black display and the color display were examined, the reflectance at white display was 6
The reflectance was 8%, and the reflectance during black display was 3%. Also,
In the color display, a clear color display could be realized due to the two-layer structure. Further, in this case, since the transmission / scattering layer is present in the color display, a fine gradation can be produced in the brightness of the display color, and a fine color tone can be produced in the color display.

In the liquid crystal display element of this embodiment, the reflectance at the time of white display is higher than that of the second embodiment.
It is considered that this is because visible light is not absorbed by the transparent electrode film and the glass substrate existing between the LC layer and the liquid crystal layer.
Further, this liquid crystal display element has a simple manufacturing process as compared with the case of the second embodiment and can be manufactured at low cost. (Comparative Example) GH having three liquid crystal layers 22 utilizing cholesteric-nematic layer transition as shown in FIG.
A cell was prepared. In the figure, 21 indicates an alignment film. As the liquid crystal material and the dichroic dyes of yellow, cyan and magenta, those similar to those in Examples 1 to 3 were used.

Regarding the obtained liquid crystal display element, white display,
When the black display and the color display were examined, the reflectance at white display was 2
The reflectance was 0%, and the reflectance when displaying black was 4%. Also,
In the color display, a clear color display could not be performed because the color remaining at the time of erasing was a problem. Therefore, this liquid crystal display element displayed darker than the liquid crystal display element of the present invention. Furthermore, this three-layer laminated structure has many manufacturing steps, is easily damaged, and has a problem in strength.

[0039]

As described above, the liquid crystal microcapsule of the present invention is obtained by encapsulating dichroic dye molecules and liquid crystal molecules with a polymer material, and the polymer material has a hue different from the hue of the dichroic dye molecule. Since it is colored, it has the property of continuously changing the hue.

Further, since the liquid crystal display device of the present invention has the liquid crystal layer containing the above-mentioned liquid crystal microcapsules, it is possible to change the hue continuously depending on the magnitude of the applied voltage, and it is possible to obtain excellent color display characteristics. Is to have.
Further, according to the liquid crystal display device of the present invention, since the liquid crystal layers can be arranged in a juxtaposed arrangement, the structure is simplified, the manufacture is simple, the mass production is suitable, and the cost is low. Furthermore, the liquid crystal display element of the present invention can display white, black, and color with one pixel, can improve the contrast, and can obtain a clear display.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a liquid crystal microcapsule of the present invention.

FIG. 2 is a diagram showing a pattern of juxtaposed alignment in a liquid crystal display device using the liquid crystal microcapsules of the present invention.

FIG. 3 is a cross-sectional view showing an example of a liquid crystal display element using the liquid crystal microcapsule of the present invention.

FIG. 4 is a sectional view showing another example of a liquid crystal display device using the liquid crystal microcapsules of the present invention.

FIG. 5 is a cross-sectional view showing another example of a liquid crystal display element using the liquid crystal microcapsule of the present invention.

FIG. 6 is a sectional view showing a liquid crystal display device of a phase transition type three-layer GH system.

[Explanation of symbols]

1 ... Dichroic dye molecule, 2 ... Liquid crystal molecule, 3 ... Polymer material,
4 ... Isotropic dye molecule, 5, 17 ... Region containing liquid crystal microcapsules showing black / red change, 6, 18 ...
Regions containing liquid crystal microcapsules changing black / green, 7, 19 ... Regions containing liquid crystal microcapsules changing black / blue, 11 ... Glass substrate,
12 ... Transparent electrode film, 13, 22 ... Liquid crystal layer, 14 ... Black / red liquid crystal microcapsule, 15 ...
Liquid crystal microcapsules changing black / green, 16 ... Liquid crystal microcapsules changing black / blue, 20 ... Transmission / scattering layer, 21 ... Alignment film.

Claims (4)

[Claims] 1. A liquid crystal microcapsule obtained by encapsulating a dichroic dye molecule and a liquid crystal molecule in a polymer material, wherein the polymer material is colored in a hue different from the hue of the dichroic dye molecule. A liquid crystal microcapsule characterized by the above. 2. A liquid crystal display device comprising a liquid crystal layer sandwiched between a pair of substrates, wherein the liquid crystal layer has a dichroic dye molecule and a liquid crystal molecule having a hue different from that of the dichroic dye molecule. A liquid crystal display device comprising liquid crystal microcapsules formed by encapsulating a colored polymer material. 3. The liquid crystal layer includes a region including liquid crystal microcapsules in which liquid crystal molecules and yellow dichroic dye molecules are encapsulated by a polymer material colored in blue, and dichroic liquid crystal molecules and cyan. A region containing liquid crystal microcapsules in which the chromophore molecule is encapsulated in a red colored polymer material, and the liquid crystal molecule and magenta dichroic dye molecule are encapsulated in a green colored polymer material. The liquid crystal display element according to claim 2, wherein the region including the liquid crystal microcapsules is arranged side by side. 4. The liquid crystal display element according to claim 2, further comprising a transmission / scattering layer provided on the liquid crystal layer.