JP2002207209A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display element with low driving voltage required and with high contrast. SOLUTION: The liquid crystal display element is characterized by being provided with a substrate, a liquid crystal layer arranged on the substrate and having a resin 11 including a liquid crystal 13 and an electrode to apply voltage to the liquid crystal layer, where the resin 11 is a copolymer formed out of a raw material containing at least one kind of monomer out of a first vinyl monomer of a main chain type or a side chain type with a short chain and a cross-inking monomer with a plurality of vinyl groups and a second vinyl monomer with a fluorine substituted alkyl chain 12 as a side chain or a second vinyl oligomer with a fluorine substituted alkyl chain 12 as a side chain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art Many liquid crystal display elements have been proposed as display devices used in information equipment and the like. At present, mainly twisted nematics disclosed in Japanese Patent Application Laid-Open No. 47-11737 are used. (TN)
Mode and super twisted nematic (ST) disclosed in JP-A-60-107020 and the like.
There is a type using a nematic liquid crystal typified by the N) mode.

[0003] These systems are known as cartode ra.
Compared to y tube (CRT) displays, they have the advantages of significantly lower power consumption and realization of a thin display panel, and are therefore widely used in office information devices such as personal computers and word processors.

[0004] A display method of the liquid crystal display element will be described. The polarization direction of the linearly polarized light incident on the liquid crystal layer of the liquid crystal display element rotates 90 ° along the twist of the liquid crystal while passing through the liquid crystal layer. When a voltage is applied to the liquid crystal layer, the liquid crystal loses its 90 ° optical rotation.

[0005] The TN mode is a method using a structure in which a liquid crystal layer is sandwiched between two linear polarizers.
The change in the optical rotation of the liquid crystal is observed as a change in the intensity of light transmitted through the liquid crystal layer.

However, in these two systems, it is difficult to say that the incident light is effectively used because the polarizer is used, and a strong light source is required.

On the other hand, as a typical liquid crystal display element using no polarizer, Polymer-Disperse is used.
d Liquid Crystal (PDLC) or Nematic Curvilineear Ali
There is a method such as gned Phase (NCAP).

In these methods, the liquid crystal layer is formed by dispersing a nematic liquid crystal material having a positive dielectric anisotropy in a polymer matrix into particles having a diameter of about several μm. The liquid crystal material is selected such that the refractive index for ordinary light is substantially the same as that of the polymer matrix, and the refractive index for extraordinary light is different from that of the polymer matrix.

In this display system, the liquid crystal in each of the liquid crystal particles has a distorted alignment structure when no voltage is applied, and the alignment direction varies among the liquid crystal particles. As a result, a difference in refractive index occurs between most of the liquid crystal particles and the polymer matrix, and as a result, light scattering occurs as in frosted glass.

When a sufficient voltage is applied to the liquid crystal layer, liquid crystal rearrangement occurs in each liquid crystal particle, and the refractive index between the liquid crystal particle and the polymer matrix with respect to the light that is perpendicularly incident on the liquid crystal layer is reduced. Become equal. As a result, there is no refraction or reflection at the interface between the liquid crystal particles and the polymer matrix, and the liquid crystal particles are in a transmission state. The incident light does not need to be linearly polarized light.

In the above-mentioned display method, since a polarizer is not required, a bright display can be performed by effectively utilizing incident light.

In the above-mentioned display system, the polymer matrix in which the liquid crystal material is dispersed in the form of particles is sealed in a glass cell used for a general liquid crystal display element, or applied to a substrate. It can be easily formed, and by mixing a dichroic dye in this liquid crystal layer,
It is also possible to cause a coloring-decoloring change.

However, at present, when the alignment direction of the liquid crystal is aligned by post-processing such as stretching in this display method, it cannot be said that the liquid crystal layer has sufficient strength. Therefore, high-contrast display cannot be performed because the alignment direction of the liquid crystal is not controlled.

Another display method without using a polarizer is as follows.
Japanese Patent Application Laid-Open No. 58-144885 and the like disclose a method of forming a large number of liquid crystal microcapsules in which a liquid crystal in a particle form is coated with a resin, and forming these into a liquid crystal layer.

As shown in FIG. 5, for example, a liquid crystal display device using liquid crystal microcapsules has a large number of liquid crystal microcapsules disposed between a glass substrate 53 on which a reflective electrode 54 is disposed and a PET substrate 55 on which a transparent electrode 56 is disposed. It is formed by laying capsules 52 and sandwiching the liquid crystal microcapsule layer 51 having a laminated structure.

Since the liquid crystal microcapsules 52 have a high degree of freedom in molding and a high strength, they can be expected as a structure of a next-generation liquid crystal display device.

However, since the size of each liquid crystal microcapsule 52 is small, the area of the wall of the liquid crystal microcapsule 52, that is, the area of the interface where the resin and the liquid crystal particles are in contact with each other is very large, so that the influence of the interface is restricted. There are many large liquid crystals. In addition, since the liquid crystal microcapsules are laid out in the liquid crystal microcapsule layer 51 and formed in a plurality of layers in series, the liquid crystal microcapsules have a structure in which a plurality of substantially thin liquid crystal microcapsule layers are connected in series. The voltage applied to the capsule layer becomes smaller. Therefore, when the liquid crystal microcapsules are used for these reasons, the driving voltage increases.

Various attempts have been made to solve these problems, but in a liquid crystal display device using liquid crystal microcapsules, there is a trade-off between low voltage driving and high contrast for the following reasons. When the driving voltage was lowered, the contrast was also lowered.

First, in order to drive at a low voltage, it is sufficient to increase the pretilt. That is, assuming that the direction A in FIG. 6 is the thickness direction of the liquid crystal microcapsule layer, as shown in the cross-sectional view of one liquid crystal microcapsule in FIG. A capsule may be formed, and the inclination angle between the resin 61 having an interface in the B direction and the liquid crystal 62 near the interface may be increased. Then, resin 6
Since the binding force at one interface is weakened, the liquid crystal 62 responds sharply even at a low driving voltage as shown in the cross-sectional view of FIG. Here, in FIG. 6, the configuration is such that a small number of liquid crystals 62 are arranged, but the actual liquid crystal is an aggregate in which many are arranged.

However, when the pretilt is increased, the inclination angle between the liquid crystal 62 and the resin 61 having an interface in the B direction is large even when no voltage is applied, so that the difference from the state when the voltage is applied becomes small and the contrast is reduced. .

On the other hand, in order to increase the contrast, a resin 6 having an interface in the B direction with the liquid crystal 62 when no voltage is applied is applied.
Although the inclination angle with respect to 1 may be reduced, the response of the liquid crystal 62 at the time of applying a voltage becomes slow because the binding force at the interface of the resin 61 increases. Therefore, it is necessary to apply a high voltage, and low-voltage driving cannot be performed.

Further, when the binding force at the resin interface is large, the liquid crystal 62 near the resin 61 interface is restrained by the resin 61 interface as shown in the cross-sectional view of one liquid crystal microcapsule in FIG. In addition, the liquid crystal 62 is oriented not only in the B direction but also in various directions, and the contrast is reduced.

[0023]

As described above, conventionally, in a display system which does not use a polarizer and has a high light utilization efficiency, a liquid crystal display device having a small driving voltage and a high contrast cannot be obtained.

Accordingly, an object of the present invention is to provide a liquid crystal display device having a low driving voltage and a high contrast.

[0025]

Accordingly, the present invention comprises a substrate, a liquid crystal layer provided on the substrate and having a resin containing liquid crystal, and an electrode for applying a voltage to the liquid crystal layer. At least one of a chain-type or short-chain side-chain first vinyl monomer, a cross-linking monomer having a plurality of vinyl groups, and a second vinyl monomer having a fluorine-substituted alkyl chain as a side chain Alternatively, there is provided a liquid crystal display element characterized by being a copolymer formed from a raw material containing a second vinyl-based oligomer having a fluorine-substituted alkyl chain as a side chain.

Further, the present invention comprises a substrate, a liquid crystal layer provided on the substrate and having a resin containing liquid crystal, and an electrode for applying a voltage to the liquid crystal layer. Second vinyl monomer having a chain or a second monomer having a fluorine-substituted alkyl chain as a side chain
The present invention provides a liquid crystal display device characterized by being a mixture comprising a polymer formed from a raw material containing a vinyl-based oligomer of (1) and a polymer.

Further, the present invention includes a substrate, a liquid crystal layer provided on the substrate and having a resin containing liquid crystal, and an electrode for applying a voltage to the liquid crystal layer, wherein the resin has a fluorine-substituted alkyl chain on the side. A first layer comprising a polymer formed from a raw material containing a second vinyl monomer having a chain or a second vinyl oligomer having a fluorine-substituted alkyl chain as a side chain; and a first layer comprising a polymer. And a second layer that covers the outside of the liquid crystal display device.

In the present invention, the ratio of the second vinyl monomer or the second vinyl oligomer in the resin is 30 w
It may be t% or less.

In the present invention, the second vinyl monomer or the second vinyl oligomer may have a fluorine-substituted C ₆ or more alkyl chain.

Further, in the present invention, the liquid crystal layer may be formed by a large number of liquid crystal microcapsules.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION In a display system using no polarizer, in order to obtain a liquid crystal display element having a low driving voltage and a high contrast, the present inventors have used a raw material of a resin containing a liquid crystal of a liquid crystal layer. It has been found that it is optimal to have a polymer containing at least a second vinyl monomer or oligomer having a fluorine-substituted alkyl chain as a side chain (hereinafter referred to as a second vinyl monomer or oligomer).

In the present invention, using the above configuration,
When no voltage is applied, the resin has an interface in the direction perpendicular to the thickness direction of the liquid crystal layer and has a liquid crystal. Provided is a liquid crystal display device which has a small response to liquid crystal in the vicinity and has a good response even when driven at a low voltage.

In the present invention, when no voltage is applied, a resin having an interface in a direction perpendicular to the thickness direction of the liquid crystal layer and containing the liquid crystal, and the inclination angle of the liquid crystal near the interface are reduced, and the interface between the resin and the resin is reduced. A method for reducing the intermolecular interaction with the liquid crystal near the interface will be described below.

Usually, when controlling the orientation of the liquid crystal, the resin in contact with the liquid crystal is subjected to a treatment such as stretching or rubbing, and the liquid crystal molecules are oriented in the direction of the stretching or the like.

In the present invention, when the second vinyl monomer or oligomer is contained as a raw material of the resin containing the liquid crystal, and when the resin is stretched, the second vinyl monomer or the second monomer in the resin is stretched. The fluorine-substituted alkyl chain of the oligomer has a property of being oriented in the stretching direction. By doing so, the liquid crystal in contact with the interface is aligned along the alkyl chain.

When no stress is applied to the resin or when the resin is shrunk, the fluorine-substituted alkyl chain of the second vinyl monomer or oligomer in the resin has a property of being oriented in a direction perpendicular to the interface. By doing so, the liquid crystal in contact with the interface is aligned along the alkyl chain.

Therefore, as a raw material of the resin containing the liquid crystal, a region having an interface in a direction perpendicular to the thickness direction of the liquid crystal layer with respect to the resin of the liquid crystal display element containing the second vinyl monomer or oligomer is provided. By performing the stretching treatment and not performing the stretching treatment in the region having the interface in the thickness direction, the fluorine-substituted alkyl chain of the second vinyl monomer or oligomer is entirely perpendicular to the thickness direction of the liquid crystal layer. Orientation. Then, along the fluorine-substituted alkyl chain, the liquid crystal as a whole is oriented in a direction perpendicular to the thickness direction of the liquid crystal layer when no voltage is applied.

For example, as a liquid crystal layer of a liquid crystal display device, FIG.
A case is shown where a liquid crystal microcapsule as shown in FIG. 1 is used, and the resin 11 constituting the liquid crystal microcapsule is a polymer containing a second vinyl monomer or oligomer as a raw material. In this case, as shown in the cross-sectional view of FIG. 1A, the fluorine-substituted alkyl chain 12 near the interface with the liquid crystal 13 controls the orientation direction of the liquid crystal 13. In FIG. 1, the direction A is defined as the thickness direction of the liquid crystal layer, and the direction B is defined as a direction perpendicular to the thickness direction of the liquid crystal.

Then, a stretching process is performed on the liquid crystal microcapsules to stretch a region having an interface in the B direction of the liquid crystal microcapsules, and no stress is applied or reduced in a region having an interface in the A direction.

Even when only the ordinary resin forming process is used and the process of stretching is not intentionally performed, the process of forming the liquid crystal microcapsules horizontally on the substrate naturally occurs due to the weight of the liquid crystal microcapsules. The film is stretched, and is stretched in the same direction as when the stretching process is performed.

Therefore, in either case, the fluorine-substituted alkyl chain 12 is oriented in the B direction at the interface with the liquid crystal 13 as a whole. Then, the fluorine-substituted alkyl chain 12 orients the liquid crystal 13 in the vicinity of the interface as a whole in a direction perpendicular to the thickness direction of the liquid crystal layer, so that the pretilt angle can be reduced and the contrast is increased.

The second vinyl monomer or oligomer has a property that the intermolecular interaction is small. Accordingly, when a voltage is applied to the liquid crystal microcapsules, the resin has a small binding force due to a small intermolecular interaction, and as shown in the cross-sectional view of FIG. Responds sharply, unaffected by chain 12. Therefore, low voltage driving becomes possible.

As described above, the present invention enables high contrast and low voltage driving. However, the effect of the present invention can be obtained only when a liquid crystal microcapsule containing liquid crystal is used as the liquid crystal layer. is not. For example, a material for forming a resin and a liquid crystal are injected into a glass cell or the like as a liquid crystal layer, a resin region is formed by a process such as a photo process, and a large number of liquid crystal minute regions are formed by the liquid crystal and a resin including the liquid crystal. If this resin is a polymer having a second vinyl monomer or oligomer as a raw material, the same effect can be obtained.

As the second vinyl monomer or oligomer, for example, a vinyl monomer such as acryl or methacryl having a fluorine-substituted alkyl chain as a side chain can be used, but is not limited thereto. Absent. Among these, those having a structure having a polar group such as acryl or a flexible alkyl chain are preferable.

In the present invention, the liquid crystal layer is composed of a liquid crystal and a resin containing the liquid crystal. In addition to the second vinyl monomer or oligomer, the resin is a side chain having a main chain type or a short chain. It is a copolymer containing, as raw materials, at least one of a first vinyl-based monomer (hereinafter, referred to as a first vinyl-based monomer) and a cross-linking monomer having a plurality of vinyl groups (hereinafter, referred to as a cross-linking monomer). Or a mixture of the polymer and a mixture containing the polymer and the polymer.

When only the second vinyl monomer or oligomer is used as a raw material, it is difficult to form a preferable resin, and too many fluorine-substituted alkyl chains are present at the interface with the liquid crystal. Since the liquid crystal does not easily enter between the fluorine-substituted alkyl chains, the effect of controlling the alignment of the liquid crystal is unlikely to appear.

Therefore, preferably, in order to make the interval between the fluorine-substituted alkyl chains about 0.3 nm or more, the other vinyl-based monomer or oligomer in the resin is reduced to about 30 wt% or less by adding other raw materials. By doing so, it becomes possible to perform good alignment control of the liquid crystal. In this case, it is preferable to use an alkyl chain of C ₆ or more, since the length of the alkyl chain is sufficient to control the alignment of the liquid crystal.

When the first vinyl-based monomer is used as a raw material for forming a resin containing liquid crystal in addition to the second vinyl-based monomer or oligomer, the first vinyl-based monomer has no long chain. In addition, there is an effect that the fluorine-substituted alkyl chain of the second vinyl monomer or oligomer increases the strength without inhibiting the function of controlling the alignment of the liquid crystal, and can form a good resin.

As the first vinyl monomer, an acrylate monomer such as methyl acrylate or a methacrylate monomer such as methyl methacrylate can be preferably used, but it is not limited to these.

When a cross-linking monomer is used as a raw material for forming a resin containing liquid crystal in addition to the second vinyl monomer or oligomer, the cross-linking monomer is cross-linked to increase the strength of the resin. It is possible,
preferable.

The crosslinking monomer is preferably a bifunctional or higher functional monomer such as divinylbenzene (DVB) or Nippon Kayaku's trimethylolpropane triacrylate (TMPT).
A) and the like can be preferably used, but the invention is not limited thereto.

When a mixture with a polymer is used as a raw material for forming a resin containing liquid crystal in addition to the second vinyl-based monomer or oligomer, the polymer has a high molecular weight. Can be increased, which is preferable. Further, a copolymer is formed by using at least one of a first vinyl monomer and a crosslinking monomer and a second vinyl monomer or oligomer as raw materials, and a polymer is formed outside the copolymer to form a plurality of resin layers. By doing so, the strength may be increased.

As the polymer, polyester and the like can be preferably used, but it is not limited to these.

Therefore, the resin containing the liquid crystal is a copolymer containing the first vinyl monomer, at least one of the crosslinking monomers, and the second vinyl monomer or oligomer as raw materials, or a polymer containing the same. Or a mixture of a polymer having a second vinyl-based monomer or oligomer as a raw material and a polymer, the preferred resin which can control the alignment of liquid crystal and obtain sufficient strength. It can be said that it can be obtained.

In the present invention, the liquid crystal layer comprises a liquid crystal and a resin containing the liquid crystal, and the resin is formed by combining a first vinyl monomer having plasticity and a second vinyl monomer or oligomer. The copolymer may be used as a raw material.

With such a structure, a copolymer containing the second vinyl monomer or oligomer for controlling the alignment of the liquid crystal and the first vinyl monomer having plasticity for the above-described reason is obtained. Form a resin with sufficient strength. Further, since the first vinyl monomer has plasticity, the resin containing these as a raw material is easily stretched, and the orientation of the fluorine-substituted alkyl chain of the second vinyl monomer or oligomer is sufficiently controlled, The alignment of the liquid crystal is also sufficiently controlled.

As the first vinyl monomer having plasticity, a thermoplastic monomer or a monomer which forms a polymer having a low softening temperature can be used. For example, methacrylic acid methacrylate, a monomer forming a polymer having rubber elasticity, and vinyl monomers such as isoprene and butadiene can be preferably used.

The liquid crystal material used in the present invention includes:
Various liquid crystal materials such as a fluorine-based liquid crystal, a cyano-based liquid crystal, and an ester-based liquid crystal can be used. Further, the dielectric anisotropy of the liquid crystal is not limited to a positive one. A liquid crystal material with a negative dielectric anisotropy and a positive liquid crystal material are mixed and used as a positive liquid crystal as a whole. May be used.

Further, a liquid crystal material having a memory property may be used. By providing the liquid crystal material with a memory property, power consumption can be reduced, and a simple matrix drive can be performed, so that a drive circuit can be simplified. In order to give the liquid crystal material a memory property, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, a cholesteric liquid crystal, or the like having hysteresis characteristics may be used. Further, fine particles may be added to the liquid crystal material, or a ferroelectric substance having a memory property may be used for the liquid crystal driving circuit.

When a liquid crystal microcapsule is used as the liquid crystal layer, a film emulsification method, an interfacial polymerization method, and “in s
Itu '' polymerization method, liquid curing coating method, phase separation method from aqueous solution system, phase separation method from organic solution system, melting dispersion cooling method, air suspension method, spray drying method, etc. What is necessary is just to select suitably according to a use, a form, etc.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these embodiments. (First Embodiment) First, a first embodiment of the present invention will be described. FIG. 2 is a cross-sectional view of the liquid crystal display device of the present embodiment.

As shown in FIG. 2, the liquid crystal display element of the present embodiment comprises a glass substrate 23, a reflective electrode 24 formed on one surface of the glass substrate 23, a PET substrate 25 facing the glass substrate 23, and a PET substrate. The liquid crystal microcapsule layer 21 is sandwiched between a transparent substrate 26 formed on one surface of the substrate 25, a glass substrate 23 with the surface on which each electrode is formed inside, and a PET substrate 25. Liquid crystal microcapsule layer 2
Reference numeral 1 denotes a configuration in which a large number of liquid crystal microcapsules 22 containing a liquid crystal by resin are spread and overlapped.

In this embodiment, the liquid crystal microcapsules 22 are composed of a liquid crystal 13 and a resin 11 covering the liquid crystal 13 as shown in FIG. 1, and the resin 11 is composed of a first vinyl monomer and a second vinyl monomer. It is a copolymer containing a monomer or oligomer and a crosslinking monomer as raw materials.

The liquid crystal microcapsules 22
Is naturally stretched by its own weight in the direction perpendicular to the thickness direction of the liquid crystal microcapsule layer 21 when it is formed on the glass substrate 23, so that it is near the interface where the resin 11 contacts the liquid crystal 13. The fluorine-substituted alkyl chain 12 of the second vinyl monomer or oligomer forms the liquid crystal 1
3 is performed.

When the resin 11 contains the first vinyl monomer and the cross-linking monomer as raw materials, the resin 11 having sufficient strength can be formed.

Next, the liquid crystal display device of the present embodiment will be described along with the manufacturing method.

First, a reflective electrode 24 having diffuse reflection is formed on one surface of a glass substrate 23 using aluminum.

Next, the liquid crystal microcapsules 22 are formed.

First, about 1 wt% of dichroic dyes G-176, D-80 and AQ-B1 manufactured by Japan Sensitive Dye Co., Ltd. as dichroic dyes of magenta, yellow and cyan, respectively.
MJ98522, a nematic liquid crystal having a positive dielectric anisotropy, which is dissolved to a total of about 89.8 wt%, manufactured by Merck Japan Ltd., and a diisobutyl fumarate monomer used as a first vinyl monomer as a raw material of the resin 11 About 7% by weight, about 1% by weight of perfluorooctylethyl acrylate monomer used as the second vinyl monomer or oligomer, and about 2% by weight of TMPTA manufactured by Nippon Kayaku Co., Ltd. used as the crosslinking monomer.
And about 0.2 wt% of benzoyl peroxide (BPO) used as a polymerization initiator are further mixed and dissolved, and about 1 wt% of polyvinyl alcohol is passed through a porous glass having a pore diameter of about 2.6 μm using a membrane emulsifier manufactured by Ise Chemical Company. After being extruded and emulsified into a pure alcohol aqueous solution stream, the mixture is stirred at about 500 rpm. This liquid crystal composition is polymerized at about 120 ° C. for about 1 hour. After polymerization, the polymer is filtered through a filter having a hole diameter of about 1 μm, and washed three times with pure water to obtain a liquid crystal microcapsule 22 covered with a transparent polymer coating film.

Next, about 50 w of ethylene glycol was added to water.
The liquid crystal microcapsules 22 are dispersed so as to have a concentration of about 65 wt% in the melted t%.

Then, a solution in which the liquid crystal microcapsules 22 are dispersed is screen-printed on the surface of the glass substrate 23 on which the reflective electrode 24 is formed, and dried to form a liquid crystal microcapsule layer 21. Liquid crystal microcapsule layer 2
The thickness of 1 is set to about 8 μm. At this time, the liquid crystal microcapsule layer 21 had a structure in which two layers of the liquid crystal microcapsules 22 were overlapped as shown in FIG.

Next, a transparent electrode 26 is formed on the PET substrate 25, and the PET substrate 25 is overlaid on the dried liquid crystal microcapsule layer 21 using a vacuum laminator. At this time, the PET substrate 25 is arranged such that the surface on the side on which the transparent electrode 26 is formed faces the surface of the glass substrate 23 on the side on which the liquid crystal microcapsule layer 21 is formed.
Then, the periphery of the substrate is sealed, and the reflection electrode 24 and the transparent electrode 26 are connected to a drive circuit (not shown) to complete the liquid crystal display device of the present embodiment.

By observing the liquid crystal display device of the present embodiment with a polarizing microscope, the liquid crystal microcapsules 22 are obtained.
Was not broken at all, and it was confirmed that the liquid crystal in the liquid crystal microcapsule 22 had an alignment state parallel to a direction perpendicular to the thickness direction of the liquid crystal microcapsule layer 21.

Further, an AC voltage of 50 Hz was applied between the reflective electrode 24 and the transparent electrode 26 of the liquid crystal display device of the present embodiment, and the display characteristics at the absorption wavelength of the dichroic dye used in the present embodiment were evaluated. . Driving was enabled when the applied voltage was set to about 5 V. The reflectance of white display was about 50%, and the contrast was about 10. This is lower voltage driving than the comparative example described later, and it can be said that sufficient contrast was obtained. (Second Embodiment) Next, a second embodiment of the present invention will be described. Regarding the liquid crystal display element of the present embodiment,
As in the first embodiment, the description will be made with reference to FIGS. 1 and 2, and the description will focus on the differences from the first embodiment.

The structure of the liquid crystal display device of this embodiment is shown in FIG.
Is the same as in the first embodiment. Then, as shown in FIG.
And a resin 11 for coating the resin. The resin 11 is composed of a first vinyl monomer, a second vinyl monomer or oligomer, a crosslinking monomer, and a plastic first vinyl monomer as raw materials. The difference from the first embodiment is that the polymer is a polymer.

The liquid crystal microcapsules 22
Is naturally stretched by its own weight in the direction perpendicular to the thickness direction of the liquid crystal microcapsule layer 21 when it is formed on the glass substrate 23, so that it is near the interface where the resin 11 contacts the liquid crystal 13. The fluorine-substituted alkyl chain 12 of the second vinyl monomer or oligomer forms the liquid crystal 1
3 is performed.

When the resin 11 contains the first vinyl monomer and the crosslinking monomer as raw materials, the resin 11 having sufficient strength can be formed. In addition, by including the first vinyl-based monomer having plasticity as a raw material, the resin 11 is sufficiently stretched with plasticity, and the orientation of the liquid crystal 13 is sufficiently controlled by the fluorine-substituted alkyl chain 12.

The method for manufacturing the liquid crystal display element of the present embodiment is as follows.
In preparing the liquid crystal microcapsules 22, as a raw material of the resin 11, about 5 wt% of a diisobutyl fumarate monomer used as a first vinyl monomer and a perfluorooctylethyl acrylate monomer used as a second vinyl monomer or oligomer are used. About 1wt
%, About 2 wt% of isoprene used as the first vinyl-based monomer having plasticity, and about 2 wt% of TMPTA manufactured by Nippon Kayaku Co., Ltd. used as the cross-linking monomer, in the same manner as in the first embodiment. And create it.

By observing the liquid crystal display device of this embodiment with a polarizing microscope, the same as in the first embodiment,
The liquid crystal microcapsules 22 were not broken at all, and it was confirmed that the liquid crystal in the liquid crystal microcapsules 22 had an alignment state parallel to a direction perpendicular to the thickness direction of the liquid crystal layer. The thickness of the liquid crystal microcapsule layer 21 is
The thickness of the liquid crystal microcapsules 22 was about 7.5 μm, as shown in FIG.

Further, an AC voltage of 50 Hz was applied between the reflective electrode 24 and the transparent electrode 26 of the liquid crystal display device of the present embodiment, and the display characteristics at the absorption wavelength of the dichroic dye used in the present embodiment were evaluated. . Driving was enabled when the applied voltage was set to about 5 V. The reflectance of white display was about 50%, and the contrast was about 12. This is lower voltage driving than the comparative example described later, and it can be said that sufficient contrast was obtained. (Third Embodiment) Next, a third embodiment of the present invention will be described. Regarding the liquid crystal display element of the present embodiment,
As in the first embodiment, the description will be made with reference to FIGS. 1 and 2, and the description will focus on the differences from the first embodiment.

The structure of the liquid crystal display device of this embodiment is shown in FIG.
Is the same as in the first embodiment. Then, as shown in FIG.
And a resin 11 covering the resin, wherein the resin 11 comprises a first vinyl-based monomer, a second vinyl-based monomer or oligomer, and a copolymer containing a cross-linking monomer as a raw material, and a polymer covering the same. Is different from the first embodiment.

The liquid crystal microcapsules 22
Is naturally stretched by its own weight in the direction perpendicular to the thickness direction of the liquid crystal microcapsule layer 21 when it is formed on the glass substrate 23, so that it is near the interface where the resin 11 and the liquid crystal 13 are in contact with each other. The fluorine-substituted alkyl chain 12 of the second vinyl monomer or oligomer controls the alignment of the liquid crystal 13.

Further, the resin contains a first vinyl monomer and a cross-linking monomer as a raw material, and further includes a polymer for covering the outer side, so that a resin 1 having sufficient strength can be obtained.
1 can be formed.

A method for manufacturing the liquid crystal display device of the present embodiment will be described. The liquid crystal display element of the present embodiment may be manufactured in the same manner as in the first embodiment until the liquid crystal microcapsules 22 are manufactured.

Next, the liquid crystal microcapsules 22 are dispersed in a pure aqueous gelatin solution of about 10 wt%, and double encapsulation is performed by a coacervation method. Thereafter, the polymer is filtered through a filter having a hole diameter of about 1 μm and washed three times with pure water to obtain liquid crystal microcapsules 22 covered with a transparent polymer coating film.

Next, about 50 w of ethylene glycol was added to water.
The liquid crystal microcapsules 22 are dispersed so as to have a concentration of about 65 wt% in the melted t%, and thereafter, a liquid crystal display element is formed in the same manner as in the first embodiment. At this time, the thickness of the liquid crystal microcapsule layer 21 is about 9 μm,
As shown in FIG. 2, the liquid crystal microcapsules 22 had a structure in which two layers were stacked.

By observing the liquid crystal display device of this embodiment with a polarizing microscope, the liquid crystal microcapsules 22
Was not broken at all, and it was confirmed that the liquid crystal in the liquid crystal microcapsules 22 had an alignment state parallel to the direction perpendicular to the thickness direction of the liquid crystal layer. Further, the resin 11 of the liquid crystal microcapsules 22 had a double structure.

An AC voltage of 50 Hz was applied between the reflective electrode 24 and the transparent electrode 26 of the liquid crystal display device of the present embodiment, and the display characteristics at the absorption wavelength of the dichroic dye used in the present embodiment were evaluated. . Driving was enabled when the applied voltage was set to about 5 V. The reflectance of white display was about 45%, and the contrast was about 9. This is lower voltage driving than the comparative example described later, and it can be said that sufficient contrast was obtained. (Fourth Embodiment) Next, a fourth embodiment of the present invention will be described. Regarding the liquid crystal display element of the present embodiment,
As in the first embodiment, the description will be made with reference to FIGS. 1 and 2, and the description will focus on the differences from the first embodiment.

The structure of the liquid crystal display device of this embodiment is shown in FIG.
Is the same as in the first embodiment. Then, as shown in FIG.
And a resin 11 that covers the second resin.
The first embodiment is different from the first embodiment in that a mixture of a polymer using a vinyl monomer or oligomer as a raw material and a polymer is used.

Then, the liquid crystal microcapsules 22
Is naturally stretched by its own weight in the direction perpendicular to the thickness direction of the liquid crystal microcapsule layer 21 when it is formed on the glass substrate 23, so that it is near the interface where the resin 11 and the liquid crystal 13 are in contact with each other. A fluorine-substituted alkyl chain 1 of a polymer of a second vinyl monomer or oligomer
2 controls the alignment of the liquid crystal 13.

Further, since the resin 11 is a mixture of a polymer and a polymer using the second vinyl monomer or oligomer as a raw material, sufficient strength can be obtained.

The manufacturing method of the liquid crystal display element of the present embodiment is as follows.
When preparing the liquid crystal microcapsules 22, the liquid crystal material containing a dichroic dye was set to about 98.8% by weight, and a perfluorooctylethyl acrylate oligomer used as a second vinyl monomer or oligomer was used as a raw material of the resin 11. Except for using 1.2 wt% and emulsifying after mixing and dissolving the liquid crystal material and the polymerization initiator with each other, extruding into a pure aqueous solution of gelatin of about 5 wt% instead of a pure aqueous solution of polyvinyl alcohol. It may be created in the same manner as in the first embodiment. Here, a mixture of the liquid crystal material, the raw material of the resin 11 and the polymerization initiator dissolved in about 100 parts by weight of the pure gelatin aqueous solution is extruded as about 20 parts by weight.

By observing the liquid crystal display device of this embodiment with a polarizing microscope, the same as in the first embodiment,
The liquid crystal microcapsules 22 were not broken at all, and it was confirmed that the liquid crystal in the liquid crystal microcapsules 22 had an alignment state parallel to the direction perpendicular to the thickness direction of the liquid crystal layer. The thickness of the liquid crystal microcapsule layer 21 is
The thickness of the liquid crystal microcapsules 22 was about 9 μm, as shown in FIG.

Further, an AC voltage of 50 Hz was applied between the reflective electrode 24 and the transparent electrode 26 of the liquid crystal display device of the present embodiment, and the display characteristics at the absorption wavelength of the dichroic dye used in the present embodiment were evaluated. . Driving was enabled when the applied voltage was set to about 5 V. The reflectance of white display was about 50%, and the contrast was about 10. This is lower voltage driving than the comparative example described later, and it can be said that sufficient contrast was obtained. (Fifth Embodiment) Next, a fifth embodiment of the present invention will be described. FIG. 3 is a cross-sectional view of the liquid crystal display device of the present embodiment.

As shown in FIG. 3, the liquid crystal display device of this embodiment comprises a pair of glass substrates 23 and a pair of glass substrates 2 opposed to each other.
3, transparent electrode 35 formed on the inner surface of transparent electrode 3
Film 3 formed on the surface of glass substrate 23 on which
1. A liquid crystal layer 33 sandwiched between a pair of opposed glass substrates 23 on which an alignment film 31 is formed.
It comprises a liquid crystal 34 and a resin wall 32 containing the liquid crystal 34.

In this embodiment, the liquid crystal 34 of the liquid crystal layer 33 is
Is coated on the alignment film 31 and the resin wall 32 as shown in FIG. 3, and the resin forming them is made of a first vinyl monomer,
The copolymer contains a second vinyl monomer or oligomer and a cross-linking monomer as raw materials.

Then, for the liquid crystal 34 in the liquid crystal layer 33,
A fluorine-substituted alkyl chain of the second vinyl monomer or oligomer near the interface between the alignment film 31 and the resin wall 32 and the liquid crystal 34 controls alignment. In addition, when the alignment film 31 and the resin wall 32 include the first vinyl monomer and the cross-linking monomer as raw materials, a copolymer having sufficient strength can be formed.

Next, the liquid crystal display device of the present embodiment will be described with reference to FIGS.

First, as shown in FIG. 4, a transparent electrode 35 is formed on one surface of each of two glass substrates 23 using ITO. Also, the diisobutyl fumarate monomer used as the first vinyl monomer is about 70 watts.
t%, about 10 wt% of perfluorooctylethyl acrylate monomer used as the second vinyl monomer or oligomer, about 18 wt% of TMPTA manufactured by Nippon Kayaku Co., Ltd. used as the crosslinking monomer, and about BPO used as the polymerization initiator. 2 wt% is mixed and dissolved, and spin-coated on the glass substrate 23 on the side where the transparent electrode 35 is formed. This is polymerized on a hot plate at about 60 ° C. for about 3 hours to form an alignment film 31.

Next, the two glass substrates 23 are bonded together with a spacer (not shown) having a diameter of about 10 μm, with the side on which the alignment film 31 is formed being inside. Then, between the glass substrates 23, dichroic dyes G-176, D-80, and AQ-
B1 is dissolved in about 1 wt% each, and MJ98522 manufactured by Merck Japan Ltd., which is a nematic liquid crystal having positive dielectric anisotropy and adjusted to a total of about 89.9 wt%, and used as a first vinyl monomer as a resin raw material About 7 wt% of a diisobutyl fumarate monomer, about 1 wt% of a perfluorooctylethyl acrylate monomer used as a second vinyl monomer or oligomer, and about 2 wt% of TMPTA manufactured by Nippon Kayaku Co., Ltd. which is used as a crosslinking monomer. A mixture obtained by mixing and dissolving AIBN manufactured by Nippon Kayaku Co., Ltd. used as a photopolymerization initiator with about 0.2 wt% is injected.

Next, a mask 41 made of Cr is bonded on a cell made of a pair of glass substrates 23 into which the liquid crystal material, the resin material, and the like are injected. This mask 41 has about 1
A large number of masking portions of about 10 μm square are formed vertically and horizontally via a space of μm.

Then, the cell is irradiated with a bright line (about 360 nm) of a high-pressure mercury lamp through the mask 41. The region irradiated with the light starts to be polymerized by the action of the photopolymerization initiator and becomes a resin, and becomes a resin wall 32 as shown in FIG. Observation with an optical microscope confirmed that a small area of the liquid crystal 34 having a size of about 10 μm and surrounded by the resin wall 32 was formed.

Next, the transparent electrode 35 is connected to a drive circuit (not shown) to complete the liquid crystal display device of the present embodiment.

The transparent electrode 35 of the liquid crystal display device of the present embodiment
An AC voltage of 50 Hz was applied therebetween, and the display characteristics at the absorption wavelength of the dichroic dye used in the present embodiment were evaluated. The liquid crystal 34 in the liquid crystal layer 33 is observed with an optical microscope, and the microscopic image of the minute area is subjected to reflection and reflection using image analysis software Image-Pro Plus manufactured by Planetron.
When the contrast was measured, driving was possible at a driving voltage of about 5 V, the reflectance of white display was about 50%, and the contrast was about 4.5. The contrast was obtained.

Also in this embodiment, when the alignment film 31 is spin-coated on the glass substrate 23 and polymerized, a stress is applied and the alignment film 31 is stretched. Since the alignment film 31 and the resin wall 32 that cover the liquid crystal 34 contain the second vinyl-based monomer or oligomer as a raw material and have a fluorine-substituted alkyl chain, the alignment of the liquid crystal can be controlled. That is, since the alignment film 31 is stretched, the liquid crystal in contact with the alignment film 31 is aligned along the surface of the alignment film 31. Further, the resin wall 32 having an interface in a direction perpendicular to the alignment film 31 is not stretched.
The liquid crystal in contact with 2 is oriented in a direction perpendicular to the resin wall 32.
Therefore, the liquid crystal is aligned entirely along the surface of the alignment film 31, that is, in the direction perpendicular to the thickness direction of the liquid crystal layer 33.

The alignment film 31 and the resin wall 32 are the first
By containing the vinyl monomer and the cross-linking monomer, sufficient strength can be obtained. (Comparative Example) Next, a comparative example will be described. In the liquid crystal display device of this comparative example, as in the first embodiment, FIGS.
This will be described with reference to FIG.

In the liquid crystal display device of this comparative example, a liquid crystal material containing a dichroic dye was made about 90 wt%, and diisobutyl fumarate monomer used as a first vinyl monomer was used as a raw material of the resin 11 of the liquid crystal microcapsules 22. About 8
wt%, and TM manufactured by Nippon Kayaku Co., Ltd.
PTA may be formed in the same manner as in the first embodiment except that about 2 wt% of PTA is used and the second vinyl monomer or oligomer is not used.

By observing the liquid crystal display device of this comparative example with a polarizing microscope, it was confirmed that the liquid crystal microcapsules 22 were not broken at all and that the liquid crystal in the liquid crystal microcapsules 22 had a random alignment state. Was done.
The thickness of the liquid crystal microcapsule layer 21 is about 8 μm.
As shown in FIG. 2, the liquid crystal microcapsules 22 had a structure in which two layers were overlapped.

Further, an AC voltage of 50 Hz was applied between the reflective electrode 24 and the transparent electrode 26 of the liquid crystal display element of this comparative example, and the display characteristics at the absorption wavelength of the dichroic dye used in this comparative example were evaluated. . When the applied voltage was set to about 15 V, driving became possible. The reflectance of white display was about 50%, and the contrast was about 5. This means that the applied voltage is higher and the contrast is lower than in the above-described embodiments of the present invention.

In this comparative example, unlike the above-described embodiments, when forming the resin 11 of the liquid crystal microcapsule 22, the alignment control such as the fluorine-substituted alkyl chain of the second vinyl monomer or oligomer is used. Since a preferable raw material is not included, it is necessary to increase the driving voltage, and the contrast is lowered.

[0111]

As described above, according to the present invention, a liquid crystal display device having a low driving voltage and a high contrast can be obtained.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional views each showing a state of a liquid crystal in a liquid crystal microcapsule of a liquid crystal display element according to a first embodiment of the present invention, and FIG. To
(B) shows a state when a voltage is applied.

FIG. 2 is a cross-sectional view illustrating the liquid crystal display device according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a process of manufacturing a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a liquid crystal display device using a conventional liquid crystal microcapsule.

6 (a) and 6 (b) are cross-sectional views showing the state of liquid crystal in a liquid crystal microcapsule of a conventional liquid crystal display element, where (a) shows a state when no voltage is applied, and (b) shows a voltage. The state at the time of application is shown.

FIG. 7 is a cross-sectional view showing a state of a liquid crystal in another conventional liquid crystal microcapsule when no voltage is applied.

[Explanation of symbols]

 11, 61 ... resin 12 ... fluorine-substituted alkyl chain 13, 34, 62 ... liquid crystal 21, 51 ... liquid crystal microcapsule layer 22, 52 ... liquid crystal microcapsule 23, 53 ... glass substrate 24, 54 ... reflective electrode 25, 55 ... PET substrate 26, 35, 56 ... Transparent electrode 31 ... Alignment film 32 ... Resin wall 33 ... Liquid crystal layer 41 ... Mask

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Seizaburo Shimizu 1st address, Komukai Toshiba-cho, Saiwai-ku, Kawasaki City, Kanagawa Prefecture (72) Inventor Katsuyuki Naito Komukai, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture No. 1, Toshiba-cho, Toshiba R & D Center (72) Inventor Yutaka Nakai No. 1, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa F-term (reference) 2H089 HA04 HA06 JA04 KA09 QA16 RA05 RA06 RA10 TA02 4J100 AB16R AB16S AL03P AL08Q AL34P AL63R AL63S AS03R BB18Q CA04 CA05 CA06 JA39

Claims (7)

[Claims] 1. A liquid crystal display device comprising: a substrate; a liquid crystal layer provided on the substrate and having a resin containing liquid crystal; and an electrode for applying a voltage to the liquid crystal layer, wherein the resin has a main chain type or a short chain type. At least one of a side chain type first vinyl monomer having a plurality of vinyl groups, and a second vinyl monomer having a fluorine-substituted alkyl chain as a side chain or a fluorine-substituted alkyl chain A liquid crystal display device comprising a copolymer formed from a raw material containing: a second vinyl oligomer having a side chain of: 2. The liquid crystal display device according to claim 1, wherein the first vinyl monomer has plasticity. 3. A substrate, a liquid crystal layer provided on the substrate and having a resin containing liquid crystal, and an electrode for applying a voltage to the liquid crystal layer, wherein the resin has a side chain of a fluorine-substituted alkyl chain. Second vinyl monomer having a chain or a second monomer having a fluorine-substituted alkyl chain as a side chain
A liquid crystal display device, comprising: a mixture comprising a polymer formed from a raw material containing a vinyl oligomer of (1) and a polymer. 4. A liquid crystal display comprising: a substrate; a liquid crystal layer provided on the substrate and having a resin containing liquid crystal; and an electrode for applying a voltage to the liquid crystal layer, wherein the resin has a fluorine-substituted alkyl chain at a side thereof. Second vinyl monomer having a chain or a second monomer having a fluorine-substituted alkyl chain as a side chain
A liquid crystal display device comprising: a first layer made of a polymer formed from a raw material containing a vinyl oligomer; and a second layer made of a polymer and covering the outside of the first layer. . 5. The method according to claim 5, wherein the ratio of the second vinyl monomer or the second vinyl oligomer in the resin is 30.
4. The liquid crystal display device according to claim 1, wherein the content is not more than wt%. 6. The method according to claim 1, wherein the second vinyl monomer or the second vinyl oligomer has a fluorine-substituted C ₆ or more alkyl chain.
5. The liquid crystal display device according to 2, 3, or 4. 7. The liquid crystal display device according to claim 1, wherein the liquid crystal layer is formed of a large number of liquid crystal microcapsules.