JPH1184395A - Liquid crystal element and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Problem] It is resistant to shock applied from the outside of a liquid crystal element,
Provided are a liquid crystal element that prevents generation of voids at low temperatures and a method for manufacturing the same. SOLUTION: A liquid crystal 1 is provided between a pair of substrates 101, 101 '.
03, the pair of substrates 10
1. A liquid crystal device in which an adhesive 110 for bonding 101 'is scattered in an effective optical modulation region, and the adhesive 110 contains a needle-like crystal, and a method of manufacturing the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device and a method for manufacturing the same.

[0002]

2. Description of the Related Art A bistable liquid crystal display device has been proposed by Clark and Lagerwall (JP-A-56-107216).
No. 4,367,924, etc.).
As a liquid crystal having bistability, a ferroelectric liquid crystal having a chiral smectic C phase (SmC ^* ) or an H phase (SmH ^* ) is generally used. This liquid crystal has a bistable state composed of a first optically stable state and a second optically stable state with respect to an electric field. Therefore, unlike a conventional optical modulation element using a TN-type liquid crystal, for example, The liquid crystal is oriented in a first optically stable state with respect to one electric field vector, and is oriented in a second optically stable state with respect to the other electric field vector.

In addition, this type of liquid crystal has a characteristic that, in response to an applied electric field, it takes one of the two stable states very quickly, and maintains that state when no electric field is applied. By constructing a liquid crystal element using a ferroelectric liquid crystal having such properties, the conventional TN
For many of the problems such as the poor viewing angle characteristics of the mold element, a substantial improvement has been obtained.

[0004]

However, in a ferroelectric liquid crystal display panel, shearing stress acts between the upper and lower substrates due to an impact from the outside of the panel, and the layer structure is destroyed, so that the alignment state is impaired. It has the essential drawback. Therefore, generally, a method is employed in which the upper and lower substrates are bonded by some method to minimize deformation due to an external impact. In order to suppress the displacement of the upper and lower substrates over the entire panel, small adhesive particles that do not affect the display are scattered and adhered to secure the overall strength.

As described above, the bonding of the upper and lower substrates copes with the destruction of the alignment in response to an external impact. However, the stronger the impact is, the more the liquid crystal material shrinks at a low temperature. A dilemma arises in that the shrinkage of the panel cannot keep up and generate voids.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art. In a liquid crystal device in which minute adhesive particles are dispersed and bonded between two substrates, the adhesive particles are used. Provided is a liquid crystal device which has both a contradictory problem in which a needle crystal is compounded therein and which is resistant to an impact applied from the outside of the liquid crystal device and prevents the generation of voids at low temperatures, and a method of manufacturing the same. The purpose is to do so.

[0007]

That is, according to the present invention, in a liquid crystal device in which a liquid crystal is sandwiched between a pair of substrates, an adhesive for bonding the pair of substrates is scattered in an effective optical modulation region, and Is a liquid crystal element characterized by containing a needle-like crystal.

According to the present invention, there is provided a method for manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of substrates, wherein a step of dispersing and disposing adhesive particles containing needle-like crystals on at least one of the pair of substrates. And a step of bonding and bonding the pair of substrates with at least the adhesive particles therebetween, and a step of injecting a liquid crystal between the pair of substrates. .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In a liquid crystal device of the present invention, in a liquid crystal device in which liquid crystal is sandwiched between a pair of substrates, an adhesive for bonding the pair of substrates is scattered in an effective optical modulation region, and the adhesive is It is characterized by containing needle-like crystals.

The present invention relates to a liquid crystal device in which a liquid crystal is arranged between two substrates having a uniaxial orientation axis, wherein needle-like crystals are contained in adhesive particles for bonding the upper and lower substrates. At the time of bonding the substrate, it gives flexible anisotropy in the cell thickness direction and rigidity in the displacement direction, is strong against impact applied from the outside of the liquid crystal element, and has contradictory characteristics to prevent voids at low temperatures. It is both.

The present invention will be described below with reference to the drawings.

FIG. 1 is a plan view showing an example of the liquid crystal element of the present invention, and FIG. 2 is a sectional view taken along the line AA 'of FIG.

The cell structure 100 shown in FIGS. 1 and 2
A pair of substrates 101 and 101 ′ made of a glass plate or a plastic plate are opposed to each other while being held at a predetermined interval by a spacer 104, and bonded with a sealant 106 made of an epoxy resin or the like to seal the pair of substrates. Further, an electrode group composed of a plurality of transparent electrodes 102 (for example, a scanning voltage application electrode group of a matrix electrode structure) is formed on the substrate 101 in a predetermined pattern such as a strip pattern. Have been.

On the substrate 101 ', the above-mentioned transparent electrode 10 is provided.
An electrode group (for example, a signal voltage electrode group in a matrix electrode structure) including a plurality of transparent electrodes 102 ′ intersecting with each other is formed.

Although an insulator film for preventing short circuit can be used for at least one of the transparent electrodes 102 and 102 ', this insulator film is not used in FIG.
Substrates 101 and 10 with 2 and 102 'respectively formed
The orientation control films 105 and 105 'are directly disposed on 1', respectively. A liquid crystal 103 is interposed between the pair of substrates 101 and 101 '.

On the orientation control films 105 and 105 ', an adhesive 110 containing a needle-like crystal, which adheres the pair of substrates 101 and 101', is scattered in the effective optical modulation region. Glued. Reference numeral 112 denotes an effective optical modulation area.

FIG. 3 is an explanatory diagram showing a portion of the adhesive 110 used in the liquid crystal element of FIG. FIG. 3A is a partial sectional view, and FIG. 3B is a partial perspective view. As shown in the figure, the adhesive 110 contains needle-like crystals 111.

In order to provide the adhesive 110, adhesive particles containing needle-like crystals 111 are dispersed and arranged on at least one of the substrates, and the two substrates are opposed to each other via the adhesive particles and bonded together. It does by doing.

The adhesive 110 may be the same as or different from the adhesive used for the sealant 106, and is not particularly limited as long as it does not adversely affect the liquid crystal. The size of the adhesive particles is such that the average particle size is 2 to 10 μm, preferably 4 to 6 μm.
m is preferred.

As the needle-like crystal 111, an insulator is used, and for example, needle-like crystals such as potassium titanate and SiC or whiskers are used.

The needle-shaped crystal has a diameter of 0.3 μm or less, preferably 0.05 to 0.10 μm, and a length of 5 μm.
The following size is desirable. The content of the needle-like crystals contained in the adhesive is preferably in the range of 0.1 to 1.0% by weight.

In the present invention, the effective optical modulation area in which the adhesive is scattered refers to an area which modulates incident light and emits it as outgoing light.

FIG. 4 is a sectional view showing another example of the liquid crystal element of the present invention. In the liquid crystal device shown in FIG.
1 ′, the short-circuit preventing insulator films 109 and l
09 ′, and an element on which the orientation control films 105 and 105 ′ are disposed.

FIG. 5 is a sectional view showing another example of the liquid crystal element of the present invention. In the liquid crystal device shown in FIG. 5, an insulating film 109 'for preventing short circuit and an orientation control film 105' are arranged on a substrate 101 ', and the orientation control film 105 is directly arranged on the substrate 101.

The alignment control films 105 and 105 'are made of inorganic materials such as silicon monoxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, boron nitride and the like. Insulating materials and organic insulating materials such as polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, urea resin and acrylic resin Can be used. The above-mentioned film of an inorganic insulating material can also function as an insulator film for preventing short circuit.

In particular, as described above, the alignment control films 105 and 105 'used in the liquid crystal device shown in FIG. 2 are formed of the above-described alignment control film and an inorganic insulator film having a function of preventing short circuit. That is, for example, an inorganic insulating material such as SiO or SiO _{2 is}
The orientation control films 105 and 105 'can be obtained by forming a film on 1' by oblique deposition.

The orientation control films 105 and 105 'are formed by forming a film of an inorganic insulating material or an organic insulating material as described above, and then rubbing (rubbing) the surface thereof in one direction with velvet, cloth or paper. A uniaxial orientation treatment is provided.

However, as shown in FIGS. 6A and 6B, the uniaxial orientation axis is aligned with the upper and lower substrates 101 and 10.
At 1 ′, they are provided so as to intersect with each other at an intersection angle (θ).

Although the crossing angle (θ) varies depending on the type of ferroelectric liquid crystal material used and the type of alignment control film, it has an optimal value corresponding to the cell gap as shown in the present invention. Only when the value is designed, the optimum operation as a display element can be realized.

The short-circuit preventing insulator films 109 and 10
9 ′ is set to a film thickness of 200 ° or more, preferably 500 ° or more, and SiO ₂ , TiO ₂ , Al ₂ O ₃ , Si ₃ N
It can be obtained by forming an inorganic insulating material such as ₄ or BaTiO ₃ .

As a film forming method, a sputtering method, an ion beam evaporation method, or a method of firing a coating film of an organic titanium compound, an organic silane compound or an organic aluminum compound can be used.

At this time, an alkyl (methyl, ethyl, propyl, butyl, etc.) titanate compound can be used as the organic titanium compound, and a general silane coupling agent can be used as the organic silane compound.

Short-circuit preventing insulator films 109 and 109 '
If the film thickness is less than 200 °, a sufficient short-circuit preventing effect cannot be obtained, and if the film thickness is 5000 ° or more, an effective voltage applied to the liquid crystal layer is not applied. Is set to 2000 mm or less.

Particularly suitable as the liquid crystal material used in the present invention is a liquid crystal exhibiting a chiral smectic phase and is a ferroelectric liquid crystal exhibiting ferroelectricity or an antiferroelectric liquid crystal.

Specifically, a chiral smectic C phase (SmC ^* ) and a chiral smectic G phase (SmG
^* ), Chiral smectic F phase (SmF ^* ), chiral smectic I phase (SmI ^* ), or chiral smectic H phase (SmH ^* ).

For details of the ferroelectric liquid crystal, for example,
EJOURNAL DE PHYSIQUE LETT
ERS "36 (L-69) 1975," Ferro e
electric Liquid crystals ":
“Applied Physics Letters”
36 (11) 1980 "Submicro Secondon
d Bi-stable Electrooptic
Switchingin Liquid Crysta
ls ":" Solid state physics "16 (141) 1981" Liquid crystal ", U.S. Pat. No. 4,561,726, U.S. Pat. No. 4,589,996, U.S. Pat.
No. 858, U.S. Pat. No. 4,596,667,
U.S. Pat. No. 4,613,209, U.S. Pat.
No. 614,609, U.S. Pat. No. 4,622,165.
In the present invention, the ferroelectric liquid crystal disclosed therein can be used.

Specific examples of the ferroelectric liquid crystal compound include decyloxybenzylidene-p'-amino-2-methylbutylcinnamate (DOBACPC) and hexyloxybenzylidene-p'-amino-2-chloropropylcinnamate (HOBACPC). ), 4-o- (2-methyl) butylresorcylidene-4'-octylaniline (MBR
8).

In the method for manufacturing a liquid crystal element according to the present invention, a step of dispersing and disposing the adhesive particles containing the needle-like crystals on at least one of the pair of substrates; The process is performed by a process of attaching and opposing each other via particles, and a process of injecting a liquid crystal between the pair of substrates. In order to inject the liquid crystal, it is particularly preferable to inject in an isotropic phase.

[0039]

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

Example 1 Two glass plates having a thickness of 1.1 mm were prepared for the upper and lower substrates, and ITO stripe electrodes were formed on each of them.
Next, Ta ₂ O ₃ was formed to a thickness of 600 ° by a sputtering method as a short-circuit preventing insulator film for the upper and lower substrate electrodes. Further, a polyimide film forming solution was formed thereon by an offset printing method, and then subjected to a heating and baking treatment at 270 ° C. for about 5 minutes on a hot plate to form a polyimide alignment film. The thickness of this polyimide alignment film was 200 °.
Next, the surface of the polyimide alignment film formed on both substrates was subjected to a rubbing treatment in the rubbing treatment axis (uniaxial orientation axis) direction.

Thereafter, silica beads having an average particle size of 1.2 μm were sprayed on one of the substrates, and then the other substrate was sprayed with adhesive particles containing needle-like crystals. The electrodes intersect in a plane and the uniaxial orientation axes of the upper and lower substrates are shown in FIG.
The upper and lower substrates were bonded together so as to form a predetermined angle θ shown in (A) to form a cell.

Next, "CS-1014" (trade name) manufactured by Chisso Corporation was vacuum-injected into the cell under an isotropic phase, and then gradually cooled to a chiral smectic phase for orientation. Was.

The pretilt angle between the liquid crystal alignment surface of the cell and the liquid crystal molecules was 20 ° as a result of measurement by a crystal rotation method.

In the structure of the cell fabricated here, the optimum characteristics were confirmed when the angle θ at which the rubbing axes of the upper and lower substrates intersect was 8 ° and the pretilt angle between the liquid crystal alignment surface and the liquid crystal molecules was 20 °. The cell gap at that time was 1.2 μm.

The adhesive particles used in this example were prepared by adding 0.1 to 1 needle-like crystals of potassium titanate (Tismo D, manufactured by Otsuka Chemical Co., Ltd.) in an amine-cured epoxy resin adhesive.
It has an average diameter of 0.5 μm with wt% added. The results of the performance comparison are shown in Table 1 below.

[0046]

[Table 1]

(Note) (1) The impact resistance property indicates the state of occurrence of orientation breakdown at 60G. (2) The low-temperature storage characteristics indicate the state of generation of voids when stored at −15 ° C. for 48 hours.

As shown in Table 1, by adding the needle-like crystals to the adhesive particles, the impact resistance and the low-temperature preservability were satisfied only in a very narrow range. It turned out to be compatible.

Example 2 In the same manner as in Example 1, the results obtained when SiC whiskers manufactured by Idemitsu Material Co., Ltd. were applied as needle-like crystal materials are shown in Table 1.
As a result, by mixing needle-like rigid crystals into the adhesive particles, it was possible to realize both the impact resistance and the low-temperature storage property incompatible properties.

[0050]

As described above, according to the present invention, 2
In a liquid crystal device that adheres by dispersing minute adhesive particles between two substrates, needle crystals are compounded in the adhesive particles to withstand the impact applied from the outside of the liquid crystal device and at low temperatures. A liquid crystal element which solves both contradictory problems that prevent the generation of voids in the liquid crystal can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing one example of a liquid crystal element of the present invention.

FIG. 2 is a sectional view taken along the line AA ′ of FIG.

FIG. 3 is an explanatory diagram showing a portion of an adhesive used in the liquid crystal element of FIG. 1;

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

FIG. 5 is a sectional view showing another example of the liquid crystal element of the present invention.

FIG. 6 is a plan view schematically showing uniaxial orientation of upper and lower substrates intersecting in the liquid crystal element of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Cell structure 101, 101 'Substrate 102, 102' Transparent electrode 103 Liquid crystal 104 Spacer 105 105 'Alignment control film 106 Sealant 107 Polarizing plate 108 Polarizing plate 109 109' Short-circuit preventing insulating film 110 Adhesive 111 Needle-like Crystal 112 Effective optical modulation area

Claims (8)

[Claims] In a liquid crystal element having a liquid crystal sandwiched between a pair of substrates, an adhesive for bonding the pair of substrates is scattered in an effective optical modulation region, and the adhesive contains a needle-like crystal. A liquid crystal element characterized by the following. 2. The crystal according to claim 1, wherein the crystal has a diameter of 0.3 μm or less and a length of 5 μm or less.
The liquid crystal element according to the above. 3. The liquid crystal device according to claim 1, wherein the crystal is an insulator. 4. The liquid crystal device according to claim 1, wherein the liquid crystal is a liquid crystal exhibiting a chiral smectic phase. 5. The liquid crystal device according to claim 1, wherein the liquid crystal is a ferroelectric liquid crystal. 6. The liquid crystal device according to claim 1, wherein the liquid crystal is an antiferroelectric liquid crystal. 7. A method for manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of substrates, wherein a step of dispersing and disposing adhesive particles containing needle-like crystals on at least one of the pair of substrates; A method for manufacturing a liquid crystal element, comprising at least a step of causing the substrates to face each other with the adhesive particles interposed therebetween and bonding the substrates, and a step of injecting a liquid crystal between the pair of substrates. 8. The method according to claim 7, wherein the liquid crystal is injected in an isotropic phase.