JPH06102495A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide the liquid crystal display element which is improved in contrast and decreased in hysteresis and to provide the liquid crystal display element which is small in driving voltage, large in area, good in contrast and has high-speed responsiveness. CONSTITUTION:This liquid crystal display element is constituted by clamping a display layer 106, which is formed by impregnating a film-like porous material 104 having open cells of <=25dyn/cm surface energy of cells with a low polymer liquid crystal compd. 105, between a pair of substrates 101 and 101' having electrodes 102, 102', at least one electrodes of which are transparent electrodes. The liquid crystal display device is constituted by providing coating layers 103, 103' exhibiting horizontal orientability in the low polymer liquid crystal compd. 105 between the display layers 106 and the electrodes 102, 102'. At least the composite film formed by impregnating the film-like porous material having the open cells with the low polymer liquid crystal compd. and the surface treatment layer exhibiting vertical orientability in the low polymer liquid crystal compd. provided on at least one surface of the composite film are clamped between a pair of the substrates having the electrodes, at least one of which are the transparent electrodes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The first invention of the present invention relates to a thermo-optic and electro-optic display device using transmitted light and scattered light,
In particular, the present invention relates to a liquid crystal display device using a display layer composed of a film-like porous material having continuous pores and a low molecular weight liquid crystal compound.

The second invention of the present invention relates to a thermo-optical and electro-optical display material using transmitted light and scattered light, and in particular, a liquid crystal using a film-like porous material having continuous pores and a low molecular weight liquid crystal compound. The present invention relates to a display element.

[0003]

[Prior art]

O Prior art of the first invention of the present invention In recent years, liquid crystals have been used for various thermo-optic and electro-optic display elements. Since these display elements require little energy for driving, research is being actively pursued even now.

As a conventional liquid crystal display element, there is known one in which a twisted nematic (TN) liquid crystal material is injected between a pair of transparent electrodes fixed at intervals of several μm. However, it is difficult to increase the area of a liquid crystal display device using this TN liquid crystal,
Further, there are problems that the electric field response is slow and the viewing angle characteristics are poor.

As an attempt to improve the problems of such a conventional type liquid crystal display device, there is a technique of using a composite film in which a low molecular weight liquid crystal compound is held in various polymer matrices as a display layer. For example, those in which a low molecular weight liquid crystal compound is encapsulated in polyvinyl alcohol (US Pat. No. 4,435,047) and those in which the capsules are connected to form a tube (US Pat. No. 4,707,080) are known.

As an example of the same type of liquid crystal display device, a mixture of a polymerizable compound and a low molecular weight liquid crystal compound is cured to form a phase-separated state, as proposed in Japanese Patent Publication No. 61-502128 and US Pat. No. 4,728,547. Fixed by means of, and as proposed in U.S. Pat. No. 4,411,495,
It is known that a porous body is impregnated with a material having a variable refractive index (including a low molecular weight liquid crystal compound).

However, these liquid crystal display elements are
Since the alignment control force due to the interface between the low molecular weight liquid crystal compound and the polymer matrix is not sufficient, it is difficult to obtain a good threshold value at the time of driving the display, and there are drawbacks such that the response speed changes in characteristics due to temperature change. Therefore, it is used in applications such as large area light control glass, but it is difficult to put it into practical use as a display element.

The present inventors have already made the surface energy of the pores 25 d in order to solve the drawbacks of the prior art.
A display material characterized by impregnating a low molecular weight liquid crystal compound into a film-like porous material having continuous pores of yn / cm or less, and a display element and a display device using the same have been proposed (Japanese Patent Application No. 3- 84544).

This liquid crystal display device is capable of displaying a large area with good contrast, no hysteresis, and good gradation, and also provides a clear interface control force to the low molecular weight liquid crystal compound. In addition, there is an advantage that the response strength at the time of voltage off (off) can be increased.

Conventional Technique of the Second Invention of the Present Invention Liquid crystals have been used in the past in various applications such as thermo-optic and electro-optic displays. Since these displays have low driving voltage and low energy consumption, active research is still ongoing.

As a conventional liquid crystal element, for example, "Applied Physics Letters" by M. Schatt and W. Helfrich.
Letters ") Volume 18, Issue 4 (1971, February 2)
Issued on the 15th of the month) Pages 127-128, "Voltage
Dependant optical activity
Of A Twisted Nematic Liquid Crystal "(" Voltage Dependent O
optical Activity of a Twis
ted Nematic liquid Crystal
l ”) shown in twisted nematic (twis)
A liquid crystal using a ted nematic liquid crystal is known. The TN liquid crystal has a problem that crosstalk occurs when it is time-divisionally driven using a matrix electrode structure having a high pixel density, and thus the number of pixels is limited.

Further, since the electric field response is slow and the viewing angle characteristic is poor, its use as a display is limited. In addition, the process of forming a thin film transistor in each pixel is extremely complicated, and it is difficult to form a large-area display element.

In order to improve the drawbacks of the conventional liquid crystal device, the use of a liquid crystal device having bistability is described by Clark and Lagerw.
all) (JP-A-56-1072).
16 publication, US Pat. No. 4,367,924, etc.).
As the liquid crystal having bistability, a ferroelectric liquid crystal having a chiral smectic C phase (Sm ^* C) or H phase (Sm ^* H) is generally used.

Since this ferroelectric liquid crystal (FLC) has spontaneous polarization, it has a very fast response speed and can exhibit a bistable state having a memory property. Furthermore, since it has excellent viewing angle characteristics, it is considered to be suitable as a material for a large-capacity, large-area display. However, when actually forming a liquid crystal cell, it is difficult to form a monodomain over a wide area, and there is a technical problem in producing a display device having a large screen.

Examples of liquid crystal display devices using polymer liquid crystals that are considered to be suitable for increasing the area include, for example, V. Shibaev, S. Kostromin, and N. Plate ( NP'late, S. Ivanov
ov), V. Vestrov,
"Polymer Communications" by I. Yakovlev ("Polymer C")
ommunications ") 24, pp. 364-365," Thermotropic Liquid Crystalline Polymers. 14 "(" Thermo-tropi
c Liquid CrystallinePolym
ers. 14 ") may be mentioned.

However, this method has not been put to practical use due to the problems that the contrast is poor because it utilizes the scattering of light for reading and that the response speed is delayed due to the polymerization. In addition to the examples shown above, attempts have been made to easily produce a liquid crystal element and increase its size.

One of them is one in which a low molecular weight liquid crystal compound is held in various polymer matrices and used.
As a specific example thereof, the one filed by Manchester R & D Partnership is known as one in which a low molecular weight liquid crystal compound is encapsulated in a polyvinyl alcohol matrix and used. (U.S. Pat. No. 4,435,047)
U.S. Pat. No. 4,707,080 is known as one in which a low molecular weight liquid crystal compound is held in a connected tubular form. These are characterized in that they are relatively easy to increase in area and have a good response speed as compared with nematic cholesteric polymer liquid crystals.

[0018]

[Problems to be Solved by the Invention]

The problem to be solved by the first invention of the present invention is that the liquid crystal display device proposed by the present inventors has a low molecular weight liquid crystal in a film-like porous material having continuous pores having a surface energy of 25 dyn / cm or less. It is impregnated with a compound. The porosity of the film-like porous material showing the content of the low-molecular liquid crystal compound in the film-like porous material having continuous pores of the liquid crystal display device is the weight X when impregnated with a liquid having a known specific gravity, From the weight Y when only the porous film is used, it is determined from the following formula (1).

[0019]

[Equation 1]

The film-like porous material has a porosity of 80 to 80.
It is used in the range of 98 vol%, preferably 85-95 vol%. If it is less than 80 vol%, the driving voltage tends to be high, which is not preferable. Further, if it exceeds 98 vol%, the strength is not sufficient, so that the production is difficult, and the durability,
It also has low heat resistance and is prone to deterioration. That is, the low molecular weight liquid crystal is used in a volume fraction of 80% to 98%, preferably 85% to 95%.

Therefore, FIG. 2 is a cross-sectional view showing an example of a conventional liquid crystal display element. As shown in FIG. 2, the film-shaped porous material 204 is impregnated with the film-shaped porous material 204 while impregnated with the film-shaped porous material 204. The display layer 20 is formed on the surface of the low-molecular liquid crystal compound 205 having no continuous pores and interfaces, that is, directly on the electrodes.
When 6 is formed, the surface of the low-molecular liquid crystal compound 205 is in contact with the surface of the electrode 202, or with an adhesive layer for fixing the porous material on the electrode, or through an insulating layer or the like. There are inevitably many parts 207.

The liquid crystal display device proposed by the present inventors has a sufficient scattering property, but in order to make a thinner device, reduce the amount of liquid crystal used, and maintain a sufficient scattering property. It is also necessary to control the interface between the impregnated low molecular weight liquid crystal compound and the electrode surface or the adhesive layer surface.

The present invention has been made as a result of intensive studies in view of the drawbacks of the above-mentioned technique, and its purpose is to keep the optical properties of the display surface of the liquid crystal display element uniform and to improve the scattering ability. It is intended to provide a liquid crystal display device having high, that is, high contrast and reduced hysteresis.

The problem to be solved by the second invention of the present invention. However, when a low molecular weight liquid crystal compound is used while being dispersed and held in a polymer matrix, the alignment control force by the interface is not sufficient, and therefore matrix driving Since it is difficult to obtain a good threshold value for this purpose, there is a drawback that it is difficult to achieve high definition even though the screen can be enlarged. Furthermore, since the light modulation method uses scattering due to the difference in refractive index between the low molecular weight liquid crystal compound and the polymer matrix, it is difficult to obtain a sufficient refractive index. As a result, sufficient extinction cannot be achieved unless the display layer is made quite thick, and the contrast is not always sufficient.

The low molecular weight liquid crystal compound described above is used by being held in various polymer matrices, and is formed when the interface between the polymer matrix and the low molecular weight liquid crystal compound is formed into an element and is, for example, rubbed. Since no clear interfacial regulation force like the alignment film is applied,
There was a problem of easy destabilization. As a result, when a drive voltage is applied, hysteresis is observed in the light transmissivity due to step-up and step-down, and when gradation display such as TV is required, image quality,
There is a problem that contrast and the like deteriorate. Further, there is a problem that the interface is likely to change due to temperature change, and the temperature characteristic of driving tends to be insufficient.

The present invention has been made in order to remedy the drawbacks of the prior art, and has a reduced threshold voltage, that is, a small driving voltage, a large area, a good contrast, and a high-speed response. It is an object of the present invention to provide a liquid crystal display element capable of performing a display having the above.

[0027]

[Means for Solving the Problems]

Means for Solving the Problem of the First Invention of the Present Invention That is, the first invention of the present invention is that the surface energy of pores is 25 dyn between a pair of substrates having electrodes in which at least one electrode is a transparent electrode. In a liquid crystal display device comprising a display layer in which a low molecular weight liquid crystal compound is impregnated in a film-like porous material having continuous pores of 1 / cm or less, the low molecular weight liquid crystal compound is horizontally aligned between the display layer and the electrode. A liquid crystal display element characterized by comprising a coat layer exhibiting properties.

The present invention will be described in detail below. According to the liquid crystal display element of the present invention, by providing a coating layer having horizontal alignment property to the low molecular weight liquid crystal compound between the display layer and the electrode, an interface between the low molecular weight liquid crystal compound and the surface of the electrode or the adhesive layer It becomes possible to obtain a liquid crystal display device having a uniform interface, a uniform optical property of the display surface, a higher scattering ability, that is, a higher contrast and a reduced hysteresis.

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an example of the display element of the present invention. In the figure, glass, plastic, etc. can be used for the substrates 101 and 101 '. Examples of the polymer film that can be used as the substrate include, but are not limited to, polyethylene terephthalate, polycarbonate film, polypropylene film and the like.

Electrodes 102 and 102 'are formed on the substrate. The electrodes are made of a transparent electrode such as ITO or SnO ₂ or A.
A metal film of l, Au, Ag, Cu, Cr or the like is used.

Further, the display layer 106 is formed on the electrodes.
In order to form the display layer 106, the film-like porous material 104 may be directly laminated or an adhesive layer (not shown) may be interposed, and the film-like porous material may be formed by the coating layer used in the present invention. A display element can also be obtained by fixing and then impregnating the low molecular weight liquid crystal compound 105.

The thickness of the display layer used is usually 0.5 to
If the thickness is less than 0.5 μm, the contrast is not sufficient, and if it exceeds 100 μm, the driving voltage becomes large, which makes high-speed driving difficult. More preferably 1 μm
A thickness of ˜50 μm is used.

In the display element of the present invention, the display layer 10
6 is a film-like porous material (matrix material) 10
A display material in which the low molecular weight liquid crystal compound 105 is contained in 4 is used. At this time, in the display layer, the porous film forms a continuous matrix, and the low molecular weight liquid crystal compound is dispersed in the form of islands or tubes. The diameter of the island or tube is preferably 0.1 to 10 μm. If the diameter of the island or tube is outside the range of 0.1 to 10 μm, the scattering efficiency is poor and sufficient contrast cannot be obtained.
More preferably, it is used at 0.5 to 5 μm. Also,
The film-like porous material has a porosity of 80 to 98 vol%.
Is preferred.

As the film-like porous material in the present invention, a polymer compound is preferably used and is practically useful because it can be easily formed into a film and has high strength. Examples of typical polymer compounds having a surface energy of 25 dyn / cm or less include the following.

Poly [(1-chlorodifluoromethyl)-
2-chloro-1,2,2-trifluoroethyl acrylate] poly (1-chlorodifluoromethyl acrylate) poly (2,2,3,3,4,4,4-heptafluorobutyl acrylate) poly (perfluoroisobutyl Acrylate) Poly [2- (N-propyl-N-heptadecafluorooctylsulfonyl) aminoethyl acrylate] Poly (2,2,3,3,4,4,5,5,6,6,7,
7,8,8,8-Pentadecafluorooctyl acrylate) Poly (1-trifluoromethyltetrafluoroethyl acrylate)

Poly [2- (2-trifluoromethyl) tetrafluoroethoxy) ethyl acrylate] Poly [5-((1-trifluoromethyl) tetrafluoroethoxy) pentyl acrylate] Poly [11-((1-trifluoro Methyl) tetrafluoroethoxy) undecyl acrylate] Poly [(1-trifluoromethyl) -2,2,2-trifluoroethyl acrylate] Poly (perfluoro-tert-butylmethacrylate) Poly [1- (chlorodifluoromethyl) Tetrafluoroethyl methacrylate]

Poly (2,2,3,3,4,4,5,5,5
6,6,7,7,8,8,8-pentadecafluorooctyl methacrylate) poly (2,2,3,3-tetrafluoropropyl methacrylate) poly (1-trifluoromethyltetrafluoroethyl methacrylate) poly (1 -Trifluoromethyl-2,2,2-trifluoroethylmethacrylate) poly [(1-trifluoromethyl) tetrafluoroethoxyethylene] poly [(1-trifluoromethyl) tetrafluoroethoxymethylethylene] poly [(1- Trifluoromethyl) tetrafluoroethoxymethyl-1-methylethylene-co-maleic acid]

Poly (heptafluoropropylethylene) Poly (tetrafluoroethylene) Poly (trifluoroethylene) Poly (trifluoromethylethylene) Poly (trifluoromethylethylene-co-tetotafluoroethylene) Poly (trifluoromethyltrifluoroethylene) ) Poly (vinylidene fluoride)

Poly [oxy-1,2-bis (perfluoroisobutoxymethyl) -ethylene] Poly [oxy-1- (3,5-bis (trifluoromethyl) phenyl) -1-trifluoroethoxymethylethylene] Poly (oxy-1-pentafluorophenyl-1-trifluoromethyltrifluoroethoxymethylethylene) Poly (oxy-1-phenyl-1-trifluoromethyl (trifluoroethoxymethylethylene)) Poly (oxy-3-trifluoro Methylphenoxymethylethylene) Poly [oxy-1- (3-trifluoromethyl) phenyl-1-trifluoromethyltrifluoroethoxymethylethylene]

Poly [(1 trifluoromethyltetrafluoroethoxymethyl) ethylene-co-maleic unhydride] Poly [1- (1-trifluoromethyltetrafluoroethoxymethyl) -1-methylene-co-maleic unhydride ] Polymer from poly (dimethylsiloxane) 3-fluoropropyltrimethoxysilane 3- (2,2,3,3,4,4,5,5,6,6,7,
Polymer from 7,8,8,8-pentadecafluorooxy) propyltriethoxysilane Polymer from 3- (1-trifluoromethyl) tetrafluoroethoxy) propyltrichlorosilane (3- (1-Trifluoromethyl) Polymers from tetrafluoroethoxy) propyltrimethoxysilane

Poly [(dodecanonylimino) ethylene] Poly [(heptanonylimino) ethylene] Poly [(hexanonylimino) ethylene] Poly [(octadecanonylimino) ethylene] Poly [(12,12,13,13 , 14, 14, 15,
15,16,16,17,17,18,18,18-Pentadecafluorooctadecanonylimino) ethylene] Poly [(pentanonylimino) ethylene] These may be used alone or in combination.

The surface energy is 25 dy when used alone.
Even if the film-like porous material is larger than n / cm,
Coating its surface with one having a low surface energy,
It can be used by adjusting the surface energy to 25 dyn / cm or less.

Plasma treatment is a preferred method for such surface modification. An example thereof is one in which a polymerizable monomer such as tetrafluoroethylene is introduced into plasma and reacted to form a polymer film. As another example, a material having a low surface energy can be obtained by introducing tetrafluorocarbon or the like into plasma and irradiating the surface-modified material.

As the film-like porous material having continuous pores which can be used for the above surface modification, Asahi Kasei Co., Ltd .: Hypore 1000, 2000, 3
000, 4000, Mitsubishi Kasei Co., Ltd .: KT-50, LE-85, Duracard, Exepol, Sekisui Chemical Co., Ltd .: Serpore, and the like, but are not limited thereto.

In the liquid crystal display device of the present invention, the coat layers 103 and 103 'are made of a low molecular weight liquid crystal compound exhibiting horizontal alignment. An example of the low-molecular liquid crystal compound exhibiting horizontal alignment is one having a surface energy of 25 dyn / cm or more at the interface with the low-molecular liquid crystal compound. The surface energy of the coating layer can be obtained from the contact angle θ of the droplet 304 formed by dropping a liquid such as water having a known surface energy on the surface of the coating layer 303, as shown in FIG. . This is because the low molecular weight liquid crystal compound impregnated in the film-like porous material having continuous pores having a surface energy of 25 dyn / cm or less is different from the alignment control force received by the interface with the film-like porous material. It means receiving regulatory power.

In addition to the surface energy at the interface with the low molecular weight liquid crystal compound being 25 dyn / cm or more, the low molecular weight liquid crystal compound is preferably horizontal alignment in the present invention. Can be used for. Further, the coat layer may function as both an insulating film and an adhesive layer.

The coat layer preferably used in the present invention is shown below, but is not particularly limited as long as it shows horizontal alignment with respect to the low molecular weight liquid crystal compound.

Polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylelline, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide, polystyrene,
Organic compounds such as cellulose resin, melamine resin, urea resin and acrylic resin, inorganic substances such as carbon monoxide, carbon dioxide, aluminum oxide and zirconia, and commercially available products applicable as such a coating layer include Hitachi Chemical HIMAL, HL series, fine polymer LQ /
LX series, Toray Semico Fine LP-72, SP
710, LP64 and the like.

The coating layer can be easily formed on the electrode or the adhesive layer by a dipping method, a spin coating method, a printing method, or the like, but the coating layer also functions as an insulating film at the same time. Therefore, the thickness of this coat layer is 100Å to 3 μm, preferably 500Å
It can be set in the range of up to 1 μm.

The surface of the coating layer is velvet,
It may have a function as an alignment control film by rubbing with cloth or paper. Further, it can be suitably used even if it is subjected to processing as seen in the oblique vapor deposition method of SiO ₂ .

Next, the display layer 106 used in the liquid crystal display element of the present invention will be described. As the display layer 106, a display material obtained by impregnating a low-molecular liquid crystal compound 105 into a film-like porous material 104 having continuous pores is used.
The film-like porous material having continuous pores used in the present invention is 25 at the interface with the low-molecular liquid crystal compound.
A material having a surface energy of dyn / cm or less is used. The surface energy at the interface is formed by dropping a liquid such as water having a known surface energy on the surface formed smoothly by the same compound as the film-like porous material in the same manner as shown in FIG. Contact angle θ
You can ask more.

In the present invention, the film-like porous material can be used as long as it has a surface energy of 25 dyn / cm or less, and more preferably 20 dyn.
/ Cm or less is used. Surface energy is 25
When it exceeds dyn / cm, the threshold voltage tends to be high and hysteresis is likely to occur, which is not preferable.

Examples of the low molecular weight liquid crystal compound used in the present invention include nematic liquid crystal, colletic liquid crystal, smectic liquid crystal and the like which are used in ordinary liquid crystal display elements, and mixtures thereof. The so-called liquid crystal phenomenon, that is, electric field , By the action of magnetic fields, electromagnetic waves, etc., and temperature action,
Any material that causes an optical change such as birefringence or light scattering may be used.

Means for Solving the Problem of the Second Invention of the Present Invention That is, the second invention of the present invention is that at least one electrode is at least continuous between a pair of substrates having electrodes which are transparent electrodes. A composite film obtained by impregnating a low-molecular liquid crystal compound into a film-like porous material having pores, and a surface treatment layer provided on at least one surface of the composite film and exhibiting vertical alignment with the low-molecular liquid crystal compound. It is a liquid crystal display element characterized in that

In the present invention, the surface energy at the interface of the surface treatment layer with the low molecular weight liquid crystal compound is 25 dy.
It is preferably n / cm or less. Further, a liquid crystal display device in which the low molecular weight liquid crystal compound has a positive dielectric anisotropy is preferable. It may have a thin film transistor between the substrates.

Further, the surface treatment layer is preferably made of a silane type surfactant, a pyridinium salt type polymer surfactant, a silicone containing resin or a fluorine containing resin. Hereinafter, the present invention will be described in detail.

According to the present invention, a surface treatment layer having vertical alignment with a low molecular weight liquid crystal compound and a composite film obtained by impregnating a low molecular weight liquid crystal compound into a film-like porous material having continuous pores are laminated. As a result, it becomes possible to vertically regulate the plane of the low-molecular liquid crystal compound that is impregnated in the film-shaped porous material and is not in contact with the film-shaped porous material, and the threshold voltage is reduced, that is, the drive voltage is reduced. It is possible to obtain a liquid crystal display device having a low contrast, a high contrast suitable for a large area, and a high-speed response.

Further, according to the present invention, the surface treatment layer has a surface energy of 25d at the interface with the low molecular weight liquid crystal compound.
By setting the yn / cm or less, and by using the silane-based surfactant, the pyridinium salt-based polymer surfactant, the silicone-containing resin or the fluorine-containing resin as the surface treatment layer, the threshold voltage is reduced, that is, It is possible to suitably exhibit a high-speed response, which has a low driving voltage, is suitable for a large area, has a good contrast, and has a high response.

Further, by using the liquid crystal display element of the present invention, good temperature characteristics in which the change in response speed with temperature is relatively small can be obtained. Further, in the present invention, since a clear interface regulating force is given to the low molecular weight liquid crystal compound, there is an advantage that the response speed when the voltage is turned off can be increased.

The present invention will be described in more detail below with reference to the drawings. FIG. 4 is a sectional view showing an example of the liquid crystal display element of the present invention. In the figure, substrates 11, 11 'can be made of glass, plastic, or the like. Examples of the polymer film that can be used as the substrate include, but are not limited to, those shown below.

That is, a low density polyethylene film,
High-density polyethylene film (Mitsui Toatsu Kagaku Hibron, etc.), polypropylene film (Toray Trefan, etc.), polyester film (DuPont Mylar, etc.), polyvinyl alcohol film (Nippon Gosei Kagaku Co., Ltd., Hi-Selon, etc.), polyamide film (Toyo Gosei film Reifan Etc.), polycarbonate film (Teijin Teijin Panlite etc.), polyimide film (DuPont KAPTON etc.), polyvinyl chloride film (Mitsubishi resin Hishirex etc.), polytetrafluoride ethylene film (Mitsui Fluorochemical Teflon etc.), polyacrylic film (Sumitomo Bakelite Sumilite), polystyrene film (Asahi Dow Styro sheet), polyvinylidene chloride film (Asahi Dow Saran film), cellulose film, polyvinyl fluoride film ( Yupon Tedlar), and the like.

The electrodes 12 and 12 'are formed on the substrate. The electrodes are transparent electrodes such as ITO and SnO ₂ or A.
A metal film of l, Au, Ag, Cu, Cr or the like is used.
The reflective display element may also serve as an electrode and a reflective layer.

Further, the surface-treated layers 13 and 13 'are formed on the electrodes. As the surface-treated layer in the present invention, a layer having vertical alignment with the low molecular weight liquid crystal compound is used.

In the present invention, it is possible to use a surface treatment layer having a surface energy of 25 dyn / cm or less, more preferably 20 dyn / cm.
cm or less is used. Surface energy is 25d
If it exceeds yn / cm, the threshold voltage tends to be high and hysteresis is likely to occur, which is not preferable.

The surface treatment layer used in the present invention includes
Polymer compounds are preferable. Examples of the polymer compound include the following.

Poly [(1-chlorodifluoromethyl)-
2-chloro-1,2,2-trifluoroethyl acrylate] poly (1-chlorodifluoromethyl acrylate) poly (2,2,3,3,4,4,4-heptafluorobutyl acrylate) poly (perfluoroisobutyl Acrylate) Poly [2- (N-propyl-N-heptadecafluorooctylsulfonyl) aminoethyl acrylate] Poly (2,2,3,3,4,4,5,5,6,6,7,
7,8,8,8-Pentadecafluorooctyl acrylate) Poly (1-trifluoromethyltetrafluoroethyl acrylate)

Poly [2- (2-trifluoromethyl) tetrafluoroethoxy) ethyl acrylate] Poly [5-((1-trifluoromethyl) tetrafluoroethoxy) pentyl acrylate] Poly [11-((1-trifluoro Methyl) tetrafluoroethoxy) undecyl acrylate] Poly [(1-trifluoromethyl) -2,2,2-trifluoroethyl acrylate] Poly (perfluoro-tert-butylmethacrylate) Poly [1- (chlorodifluoromethyl) Tetrafluoroethyl Methacrylate] Poly (2,2,3,3,4,4,5,5,6,6,7,7,
7,8,8,8-Pentadecafluorooctyl methacrylate)

Poly (2,2,3,3-tetrafluoropropylmethacrylate) Poly (1-trifluoromethyltetrafluoroethylmethacrylate) Poly (1-trifluoromethyl-2,2,2-trifluoroethylmethacrylate) Poly [(1-Trifluoromethyl) tetrafluoroethoxyethylene] Poly [(1-trifluoromethyl) tetrafluoroethoxymethylethylene] Poly [(1-trifluoromethyl) tetrafluoroethoxymethyl-1-methylethylene-co-maleic acid ]

Poly (heptafluoropropylethylene) Poly (tetrafluoroethylene) Poly (trifluoroethylene) Poly (trifluoromethylethylene) Poly (trifluoromethylethylene-co-tetotafluoroethylene) Poly (trifluoromethyltrifluoroethylene) ) Poly (vinylidene fluoride)

Poly [oxy-1,2-bis (perfluoroisobutoxymethyl) -ethylene] Poly [oxy-1- (3,5-bis (trifluoromethyl) phenyl) -1-trifluoroethoxymethylethylene] Poly (oxy-1-pentafluorophenyl-1-trifluoromethyltrifluoroethoxymethylethylene) Poly (oxy-1-phenyl-1-trifluoromethyl (trifluoroethoxymethylethylene)) Poly (oxy-3-trifluoro Methylphenoxymethylethylene) Poly [oxy-1- (3-trifluoromethyl) phenyl-1-trifluoromethyltrifluoroethoxymethylethylene]

Poly [(1 trifluoromethyltetrafluoroethoxymethyl) ethylene-co-maleic unhydride] Poly [1- (1-trifluoromethyltetrafluoroethoxymethyl) -1-methylene-co-maleic unhydride ] Polymer from poly (dimethylsiloxane) 3-fluoropropyltrimethoxysilane 3- (2,2,3,3,4,4,5,5,6,6,7,
Polymer from 7,8,8,8-pentadecafluorooxy) propyltriethoxysilane Polymer from 3- (1-trifluoromethyl) tetrafluoroethoxy) propyltrichlorosilane (3- (1-Trifluoromethyl) Polymers from tetrafluoroethoxy) propyltrimethoxysilane

Poly [(dodecanonylimino) ethylene] Poly [(heptanonylimino) ethylene] Poly [(hexanonylimino) ethylene] Poly [(octadecanonylimino) ethylene] Poly [(12,12,13,13 , 14, 14, 15,
15,16,16,17,17,18,18,18-Pentadecafluorooctadecanonylimino) ethylene] Poly [(pentanonylimino) ethylene] These may be used alone or in combination.

Further, commercially available modifiers such as silicon-based surface modifiers and fluororesin-based surface modifiers can be used as the surface treatment layer. As a specific example, Surflon SC-101 (manufactured by Asahi Glass Co., Ltd.), Florard FC-
725, FC-722 (manufactured by 3M Co.), silicon coating agent SR2410, DC-1-2577, silane coupling agent SH6020, SZ6083 (manufactured by Toray Silicone Co., Ltd.) and the like, but not particularly limited thereto. .

Further, the surface energy alone is 25 dy.
Even a polymer compound having a molecular weight larger than n / cm can be used by surface-modifying the surface so that the surface energy is 25 dyn / cm or less.

Plasma treatment is a preferred method for such surface modification. An example thereof is one in which a polymerizable monomer such as tetrafluoroethylene is introduced into plasma and reacted to form a polymer film. As another example, a material having a low surface energy can be obtained by introducing tetrafluorocarbon or the like into plasma and irradiating the surface-modified material.

In the present invention, the surface energy at the interface is the contact angle of the droplet 24 formed by dropping a liquid such as water having a known surface energy on the surface of the surface treatment layer 23 formed as shown in FIG. It can be obtained from θ.

That is, the surface energy of the liquid is γ _l ,
Assuming that the surface energy of the surface treatment layer formed smoothly is γ _s and the energy of the solid-liquid interface is γ _i , γ _s = γ
It can be expressed as _i + γ _l cos θ. [Fox, Hetch. W-End Thisman, W. A. (Fox, H.W and Zisma
n, W. A. ) “Journal of Colloid Science (J. ColloidSci.), 5 , 514 (1950)] In general, it is possible to set the energy γ _i = 0 of the solid-liquid interface, and the surface energy of water (20 ° C., 72 ° C.). .8 dy
The surface energy at the interface of the surface treatment layer can be determined from (n / cm) and the contact angle.

Further, the display layer 16 is formed by laminating the film-like porous material 14 having continuous pores on the core surface-treated layer and then impregnating the low-molecular liquid crystal compound 15 therein.

The thickness of the display layer used is usually 0.5 to
When the thickness is less than 0.5 μm, the contrast is not sufficient, and when the thickness exceeds 100 μm, the driving voltage is large and high-speed driving becomes difficult. More preferably, 1 to 50
A thickness of μm is used.

At this time, in the display layer, the film-like porous material forms a continuous matrix, and the low molecular weight liquid crystal compound is dispersed in the form of islands or tubes. The diameter of the island or tube is preferably 0.1 to 10 μm. If the diameter of the island or tube is outside the range of 0.1-10 μm,
The scattering efficiency is poor and sufficient contrast cannot be obtained. More preferably, it is used at 0.5 to 5 μm.

In the present invention, the film-like porous material having continuous pores is used in combination with an incompatible low molecular weight liquid crystal compound, but the film-like porous material having continuous pores continuously forms a matrix. Just do it. The proportion of the filmy porous material having continuous pores used is usually 10 to 70 wt%. If it is less than 10 wt%, it is difficult to sufficiently control the orientation of the low molecular weight liquid crystal compound due to the reduction of the matrix effect, and if it exceeds 70 wt%, the ratio of the change in the refractive index due to the low molecular weight liquid crystal compound is reduced and the contrast is sufficiently high. It is not preferable because it cannot be removed. More preferably, the proportion of the filmy porous material having continuous pores is 10 to 50 wt%.

As the film-like porous material having continuous pores as described above, Asahi Kasei Kogyo Co., Ltd .: Hypore 1000, 2000, 3
000, 4000, Mitsubishi Kasei Co., Ltd .: KT-50, LE-85, Duracard, Exepol, Sekisui Chemical Co., Ltd .: Serpore, and the like, but are not limited thereto.

Further, in the present invention, as the low molecular weight liquid crystal compound, nematic liquid crystal having a positive dielectric anisotropy used for ordinary liquid crystal display elements is preferably used.

Further, as shown in FIG. 6, in the present invention, a thin film transistor 38 is formed together with an electrode 32 'on a substrate 31', and a surface treatment layer 37 is formed on the thin film transistor 38, so that excellent TFT driving can be achieved. It can be a liquid crystal display element capable of

In the liquid crystal display device of the present invention, when the effect of heating is used for display, a thermal head or laser light can be used. As the laser light, He-Ne gas laser, Ar ²⁺ gas laser, N
Gas lasers such as ₂ gas lasers, ruby lasers,
Solid-state laser such as glass laser, YAG laser,
It is desirable to use a semiconductor laser or the like. Also, 60
A semiconductor laser having a wavelength range of 0 nm to 1600 nm is preferably used. Particularly preferably 600 to 900 nm
A semiconductor laser in the wavelength range of is used. Further, the wavelength can be shortened by using the second and third harmonics of these laser lights.

When laser light is used, a light absorbing layer is provided separately, or a laser light absorbing compound is dispersed and dissolved in the display layer before use. When the display surface is affected by the light absorbing layer or the light absorbing compound, it is desirable that the material does not absorb in the visible light region.

Examples of the laser light absorbing compound added to the display layer include azo compounds, bisazo compounds, trisazo compounds, anthraquinone compounds, naphthoquinone compounds, phthalocyanine compounds, naphthalocyanine compounds, and tetrabenzoporphyrin. System compounds, aminium salt compounds, diimonium salt compounds, metal chelate compounds and the like.

Of the above laser light absorbing compounds, the compounds for semiconductor lasers have absorption in the near infrared region, are useful as stable light absorbing dyes, and have good compatibility or dispersibility with the film-like porous material. . Further, some of them have dichroism, and if these compounds having dichroism are mixed in the film-like porous material, a thermally stable host-guest type memory and display medium can be obtained. You can also Further, two or more kinds of the above compounds may be contained in the film-shaped porous material.

Further, the above compounds may be combined with other near infrared absorbing dyes or dichroic dyes. Representative examples of near-infrared absorbing dyes that can be suitably combined are cyanine, merocyanine, phthalocyanine, tetrahydrocholine, dioxazine, anthraquinone, triphenodithiazine, xanthene, triphenylmethane, pyrylium, croconium, azulene and triphenylamine. And the like. The amount of the above compound added to the film-like porous material is about 0.1 to 20% by weight, preferably 0.5 to 10%.

[0090]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example of the first invention of the present invention Example 1 2000 pieces of ITO were formed on a pair of glass substrates having a thickness of 1.1 mm.
HIMAL HL-1110 manufactured by Hitachi Chemical Co., Ltd. was applied as a coating layer to a substrate having a transparent electrode vapor-deposited to a thickness of Å by a spin coating method to a thickness of 3000 Å and then dried. Kyowa Interface Science Co., Ltd., contact angle meter CA-S150 was used to measure the contact angle for water droplets, and the surface energy was calculated to be 42d.
It was yn / cm (20 ° C.). In addition, E on the dry coating film
ZLI-2008 (nematic liquid crystal) manufactured by Merck & Co. was dropped and the liquid crystal showed horizontal alignment when observed with a polarizing microscope.

Hypore 3000 (film thickness: 50 μm, porosity: 90, manufactured by Asahi Kasei Corporation) was placed on a 1 cm square in the center of the glass substrate.
%) And the three sides are surrounded by an adhesive (Mitsui Toatsu Chemicals, Struct Bond EH454NF) containing a glass fiber spacer (Nippon Denshi Glass, 50 μmφ), and the above-mentioned pair of glass substrates are bonded. A cell structure was formed by curing the layers together. This cell was decompressed, and the capillary method was used for ZLI-2008 manufactured by E-Merck.
(Nematic liquid crystal) was impregnated and injected.

± 100 V, 60 between the upper and lower substrates of this cell
When a square wave of Hz was applied, it was in a transparent state with a voltage on,
It becomes cloudy when the voltage is off, and the contrast is 15: 1.
And was good. Almost no hysteresis due to step-up or step-down of voltage was observed.

Comparative Example 1 A cell was prepared in the same manner as in Example 1 except that a vinyl acetate resin adhesive: Cemedine 198L was used as a coat layer on a substrate with transparent electrodes, and a rectangle of ± 100 V, 60 Hz was provided between the upper and lower substrates. When a wave was applied, the voltage was turned on and the transparent state was obtained.
Although it became cloudy when the voltage was off, the contrast was insufficient at 10: 1 due to the high transmittance in the cloudy state, and the applied voltage at a transmittance of 50% had a difference of 6 V when the voltage was increased or decreased. It occurred as hysteresis.

Example 2 When a cell was prepared and a voltage was applied in the same manner as in Example 1 except that Himaru: LQ-2200 (manufactured by Hitachi Chemical Co., Ltd.) was used as the coating layer, the contrast was as good as 18: 1. Almost no hysteresis was observed.

Example of the Second Invention of the Present Invention Example 3 A glass substrate on which an ITO electrode (thickness 1000Å) was vapor-deposited was spin-coated (thickness 5000Å) with a surface treatment layer (Florard FC-722). Formed. The surface energy of the surface was 22 dyn / c when the contact angle was measured with a CA-S150 contact angle meter manufactured by Kyowa Interface Science Co., Ltd.
It was m. In addition, ZLI 2008 manufactured by E-Merck Co., Ltd.
When (nematic liquid crystal) was dropped on the surface and observed with a polarizing microscope, it showed vertical alignment.

Two above-mentioned substrates were prepared, the surface treatment layer surfaces were opposed to each other, and the three sides were sealed with an epoxy adhesive, and
Film-like porous material with continuous pores: Asahi Kasei Corporation
Manufactured by Hipore 3000 (film thickness 50 μm). After heating and curing, the mixture was allowed to cool to room temperature, the cell was depressurized, the open end was immersed in the nematic liquid crystal composition, and the liquid crystal compound was impregnated by returning to normal pressure.

100 V, 60 H between the upper and lower substrates of this cell
When a rectangular wave of z was applied, the rise time at the voltage on was 0.5 ms and the fall time at the voltage off was 0.6 ms, which were fast. The threshold voltage of this cell (voltage at 10% light transmission) was as low as 52V.

Example 4 As the surface treatment layer, a silicon coating agent: Toray Industries, Inc., DC-1-2577 xylene solution was used.
A cell was prepared in the same manner as in Example 3 except that Fluoropore (membrane pressure 100 μm) manufactured by Sumitomo Electric Industries, Ltd. was used as the film-like porous material having continuous pores.
When a rectangular wave of 0 V and 60 Hz was applied, the rise time at the voltage on was 0.5 ms and the fall time at the voltage off was 0.7 ms, which were fast.

The surface energy of the interface coated with the silicon coating agent was 21 dyn / cm. Further, when a liquid crystal compound similar to that in Example 3 was dropped and observed with a polarization microscope, it showed vertical alignment. The threshold voltage of this display cell was 81 V, which was good.

Comparative Example 2 As a surface treatment layer, Gosenol GL-05, 10 wt% aqueous solution, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. was applied in the same manner as in Example 3, and the surface energy was measured after heating and drying.
It was n / cm. Further, when the same liquid crystal compound as in Example 3 was dropped and observed with a polarization microscope, no vertical alignment was shown.

When a cell was prepared using this substrate in the same manner as in Example 1 and a voltage was applied, the rise time at the voltage on was 1.0 ms and the fall time at the voltage off was 1.2 ms. The threshold voltage was high at 68V.

Examples 5 to 8 and Comparative Example 3 A cell was prepared in the same manner as in Example 3 except that the surface treatment layer was replaced.
In addition, surface energy, vertical orientation, voltage on and off
Table 1 shows the results of measuring and observing the response time and threshold voltage
Shown in.

[0104]

[Table 1]

(Note) The surface treatment layer is shown below.

Example 3: A ... Florard Example 4: B ... Silicon coating agent Example 5: C ... Silane coupling agent Example 6: D ... Silane coupling agent Example 7: E ... Silicon spray Example 8 : F ... TFE (tetrafluoroethylene) spray Comparative example 2: G ... PVA (polyvinyl alcohol) Comparative example 3: H ... PVB (polyvinyl butyral)

[0107]

【The invention's effect】

As described above, according to the present invention, a low molecular weight liquid crystal compound is added to a film-like porous material having continuous pores having a surface energy of pores of 25 dyn / cm or less as a display layer. The low molecular weight liquid crystal is used between a display layer and an electrode of a display element sandwiched between a display layer and a pair of substrates having an electrode in which at least one electrode is a transparent electrode, using a display material impregnated. By providing the coating layer having horizontal orientation with respect to the compound, a liquid crystal display device having high scattering ability, that is, improved contrast and reduced hysteresis can be obtained.

Further, since it becomes possible to regulate the orientation of the low molecular weight liquid crystal compound which is not in contact with the film-shaped porous material while being impregnated in the film-shaped porous material having continuous pores, it is possible to obtain a display element. Optical uniformity of the display surface can be obtained.

Effect of the Second Invention of the Present Invention As described above, according to the present invention, surface treatment is performed on the electrode surface sandwiching the polymer-dispersed liquid crystal and / or the porous impregnated liquid crystal display layer. By providing vertical alignment at the interface with the liquid crystal, it is possible to obtain a liquid crystal display element having a reduced threshold voltage and a high-speed response.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a liquid crystal display element of the present invention.

FIG. 2 is a cross-sectional view showing an example of a conventional liquid crystal display element.

FIG. 3 is an explanatory diagram showing a method for measuring the surface energy of a coat layer of the present invention.

FIG. 4 is a sectional view showing an example of a liquid crystal display element of the present invention.

FIG. 5 is an explanatory diagram showing a method of measuring the surface energy of the surface treatment layer.

FIG. 6 is a cross-sectional view showing an example including a thin film transistor of the liquid crystal display element of the present invention.

[Explanation of symbols]

 101, 101 ', 201, 201', 301 Substrate 102, 102 ', 202, 202', 302 Electrode 103, 103 ', 303 Coat layer 104, 204 Film-like porous material 105, 205 Low molecular weight liquid crystal compound 106, 206 Display layer 207 Area where electrode surface contacts low-molecular liquid crystal compound 304 Droplet θ Contact angle 11, 11 ', 21, 31, 31' Substrate 12, 12 ', 22, 32, 32' Electrode 13, 13 ', 23 , 36, 37 Surface treatment layer 14, 34 Film-like porous material 15, 35 Low molecular weight liquid crystal compound 16, 33 Display layer 24 Droplet 38 Thin film transistor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryoji Fujiwara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takeo Eguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (7)

[Claims] 1. The surface energy of pores is 2 between a pair of substrates having at least one electrode which is a transparent electrode.
A liquid crystal display device comprising a display layer in which a low molecular weight liquid crystal compound is impregnated in a film-like porous material having continuous pores of 5 dyn / cm or less, and the low molecular weight liquid crystal compound is horizontally disposed between the display layer and the electrode. A liquid crystal display device comprising a coat layer exhibiting orientation. 2. The film-shaped porous material has a porosity of 80.
The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a content of about 98 vol%. 3. A composite film in which a low molecular weight liquid crystal compound is impregnated in a film-like porous material having at least continuous pores between a pair of substrates having at least one electrode which is a transparent electrode, and the composite film. 2. A liquid crystal display device, comprising: a surface treatment layer provided on at least one surface of the low molecular weight liquid crystal compound and exhibiting vertical alignment. 4. The liquid crystal display device according to claim 3, wherein the surface energy at the interface of the surface treatment layer with the low molecular weight liquid crystal compound is 25 dyn / cm or less. 5. The liquid crystal display device according to claim 3, wherein the low molecular weight liquid crystal compound has a positive dielectric anisotropy. 6. The liquid crystal display device according to claim 3, wherein the surface treatment layer is a silane-based surfactant, a pyridinium salt-based polymer surfactant, a silicone-containing resin or a fluorine-containing resin. 7. The liquid crystal display element according to claim 3, further comprising a thin film transistor between the substrates.