JPH11190851A - Liquid crystal element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the alignment abnormality of liquid crystals by the components eluted from barrier members for imparting impact resistance to a cell of a liquid crystal element using chiral smectic liquid crystals. SOLUTION: Striped electrodes 12, 22, inorg. insulating films 13, 23, coating type insulating films 14, 24 and alignment layers 15, 25 are formed respectively on substrates 11, 21. A polyvinyl alcohol compsn. contg. a photosensitive agent is applied on the alignment layers 15, 25 and is subjected to pattern exposure and development to form the barrier members 16. Another substrate is superposed thereon and is heated to adhere the upper and lower substrates 11, 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal element used for a liquid crystal display device, a liquid crystal optical shutter and the like.

[0002]

2. Description of the Related Art Clark and Lagerwall have proposed a display device in which transmitted light is controlled in combination with a polarizing element utilizing the refractive index anisotropy of ferroelectric liquid crystal molecules. (JP-A-56-107216, U.S. Pat.
369924, etc.). The ferroelectric liquid crystal generally has a non-helical chiral smectic C phase (SmC ^* ) or H phase (SmH ^* ) in a specific temperature range, and in this state, responds to an applied electric field. One of the first optical stable state and the second optical stable state, and maintaining the state when no electric field is applied, that is, it has bistability, and has a response corresponding to a change in the electric field. It is also expected to be widely used as a high-speed and storage-type display element. In particular, its function is expected to be applied to a large-screen, high-definition display element using a simple matrix driving method.

In particular, in the case of a ferroelectric liquid crystal, a cell gap indicating a gap between a pair of opposed substrates is about 1 μm.
Extremely narrow compared to other liquid crystals. In order to bond the entire screen with the same cell gap, a uniform glass spacer having a particle size of 1 μm is sprayed, and adhesive beads made of a thermosetting epoxy resin are also sprayed. However, in a liquid crystal panel bonded using an adhesive bead, the liquid crystal moves when subjected to an external impact, and the chevron structure or the bookshelf structure peculiar to the ferroelectric liquid crystal is destroyed. In order to prevent this, a housing design excellent in impact resistance is required for commercialization.

On the other hand, a method is also known in which a partition member made of polyimide or acrylic resin having adhesiveness and photosensitivity is provided on an alignment film, and a pair of substrates facing each other are bonded instead of the adhesive beads. In this case, the shock resistance of the liquid crystal panel is greatly improved because the partition member itself absorbs the shock and the movement of the liquid crystal by the shock is hindered by the partition.

[0005]

However, by forming the partition member, a difference is easily generated between the pretilt of the substrate on which the partition member is provided and the pretilt of the opposing substrate. In this case, the property of the ferroelectric liquid crystal to maintain two stable states, that is, the bistability is broken, and only one stable state is exhibited. In this case, the drivability of the liquid crystal is significantly impaired.

Further, polyimide or acrylic resin which has been conventionally used as a material for a partition member requires a high-temperature treatment of 200 ° C. or more for heat curing, and such a high-temperature treatment affects an underlying alignment film and causes ferroelectricity. The pretilt of the crystalline liquid crystal is changed by about 5 ° with respect to the control value of 16 to 18 °. In addition, when the material is cured at a low temperature, the solvent contained in the material of the partition member or a component eluted from an unreacted substance may cause an abnormal alignment of liquid crystal around the partition member.

Further, in a patterning process using a polyimide or an acrylic resin, a resist obtained by dissolving these resins together with a photosensitive agent in a solvent is coated on an alignment film, and is sequentially subjected to pre-baking, exposure, development / rinsing, and post-baking. However, when alkanolamine or inorganic alkali used as a developer remains in a fine region between the partition member and the alignment film, it is gradually eluted into the liquid crystal some time after the injection of the liquid crystal, causing abnormal liquid crystal alignment. Cause. Further, a solvent such as NMP (N-methylpyrrolidone), which generally easily dissolves an additive contained in the resin from the resin and damages the resin, is also used as a developer for patterning the partition member. Even when such a solvent remains on the surface of the alignment film, the alignment of the liquid crystal is adversely affected.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a liquid crystal element with impact resistance by forming a partition member for bonding the upper and lower substrates, and at the same time, prevent the deterioration of the alignment of the liquid crystal due to the partition member forming material component. To provide a highly reliable liquid crystal element.

[0009]

A first aspect of the present invention is a liquid crystal element in which liquid crystal is sandwiched between a pair of substrates each having an electrode, wherein the pair of substrates are provided with a photosensitive agent in a display section. Is bonded by a partition member made of a polyvinyl alcohol composition containing

A second aspect of the present invention is the above-mentioned method for producing a liquid crystal device according to the first aspect of the present invention, wherein a polyvinyl alcohol composition containing a photosensitive agent is applied to one substrate surface, and after pattern exposure, water is applied. Forming a partition member by developing,
The other substrate is overlaid, the partition member is heated and cured, and the pair of substrates is bonded.

In the present invention, the partition member for bonding the upper and lower substrates is formed of a polyvinyl alcohol composition containing a photosensitive agent, so that the partition member can be heated and cured by one time.
It can be performed at a low temperature of about 50 ° C. which does not affect the pretilt of the alignment film. In addition, since the composition can be developed with water after coating and pattern exposure, even when the composition remains, there is no fear that the liquid crystal alignment is adversely affected unlike an organic / inorganic alkali or solvent-based developer. .

In particular, in the manufacturing method of the present invention, after the partition member is formed on the alignment film, the alignment film is subjected to a rubbing treatment, so that the pretilt difference between the upper and lower substrates before and after the formation of the partition member is independent. Can be kept within 2 °.

Further, in the present invention, the above-mentioned partition member can be used as a sealing material, and the step of drawing the sealing material can be omitted, and at the same time, components such as chlorine ions and sulfate ions from the sealing material that adversely affect the liquid crystal alignment. Can also be solved.

[0014]

FIG. 1 is a schematic partial sectional view of an embodiment of the liquid crystal device of the present invention. In the figure, 11 and 21 are substrates, 12 and 22 are electrodes, 13 and 23 are inorganic insulating films, 1
Reference numerals 4 and 24 are coating type insulating films, 15 and 25 are alignment films, 16 is a partition member, 17 is a hard particulate spacer for determining the distance between substrates, and 18 is a liquid crystal compound.

In the present invention, as the substrates 11 and 21, generally used glass substrates are used. However, the present invention is not limited thereto, and plastics and the like are preferably used as long as they have necessary characteristics such as transparency and strength. Can be The electrodes 12 and 22 are usually formed of a transparent conductive material such as ITO. In the present embodiment, the electrodes 12 are formed in stripes in a direction parallel to the paper and the electrodes 22 are formed in stripes in a direction perpendicular to the paper, and are arranged so as to be orthogonal to each other. Have been.

The alignment films 15 and 25 are provided on the interface between at least one of the substrates and the liquid crystal, and are usually subjected to a uniaxial alignment process. In the present invention, as the alignment films 15 and 25, polyimide, polyamide, polyamideimide, nylon or the like is preferably used. Specifically, for example, “LQ1802-01” manufactured by Hitachi Chemical Co., Ltd. is used. The film thickness is preferably about 200 to 170 °, and the film can be formed by printing on a color-developed plate.

In the present invention, the alignment film 25 on the substrate 21 on the side on which the partition member 15 is provided is preferably subjected to a rubbing treatment after the formation of the partition member 15, thereby forming Can impart orientation controllability irrespective of.

In the liquid crystal device of the present invention, if necessary, electrodes 12 and
An insulating film is formed on 22. In the present embodiment,
A configuration in which inorganic insulating films 13 and 23 as short-circuit prevention layers and coating-type insulating films 14 and 24 for assisting short-circuit prevention are combined is shown. As such inorganic insulating films 13 and 23, for example, Ta ₂ O ₅ , TiO ₂ , and SiO ₂ are preferably used. The coating type insulating films 14 and 24 are made of T
i-Si or the like is preferably used.

The partition member 16 according to the present invention is formed of a polyvinyl alcohol composition containing a photosensitive agent. As such a composition, for example, "SPP-776" manufactured by Toyo Gosei Kogyo Co., Ltd. is preferably used.

In the present invention, the partition member 16 is formed in a stripe shape or a dot shape. Preferably, the partition member 16 has one of the electrodes (the electrode 22 in the present embodiment) on one substrate so as not to lower the aperture ratio of the pixel. Form in the gap. The height of the partition member 16, that is, the cell gap is formed to be 5 μm or less when, for example, a chiral smectic liquid crystal is used.

In the present invention, the partition member 1 is used.
When forming 6, a sealing material can be formed by forming a partition pattern having a width of about 3 mm also on the periphery of the substrate 21.

The spacer used in the present invention is a conventionally used bead spacer made of glass, SiO ₂ or the like, and has a particle diameter that determines a desired cell gap.

The liquid crystal used in the present invention is not particularly limited, and a liquid crystal which has been widely used in the past, such as a TN type, can be used. A remarkable effect is obtained when a chiral smectic liquid crystal such as a dielectric liquid crystal is used.

The liquid crystal device according to the present invention comprises a substrate 11 and a substrate 11 on which necessary members such as an insulating film, an alignment film and a partition member are formed.
Liquid crystal is injected into a cell obtained by laminating 1 and heating to cure the sealant and the partition member, and the liquid crystal injection port is sealed. Further, the liquid crystal element of the present invention is usually used by being sandwiched between a pair of polarizing plates (in the case of a transmission type).

In the above embodiment, the liquid crystal element having a simple matrix structure has been described. However, the present invention is not limited to the liquid crystal element having the electrode structure, but an active matrix type liquid crystal element using a switching element such as a TFT. It can also be applied to

Further, the present invention is not limited to the configuration of the above-described embodiment, and the technology of the conventional liquid crystal element can be applied to configurations other than the configurations limited in claims 1 and 8 of the present invention.

[0027]

EXAMPLES Example 1 A 700-mm-thick ITO film was formed on each of two glass substrates having a thickness of 1.1 mm by sputtering, and was patterned by photolithography into stripes having a width of 200 μm and a gap of 10 μm. Thus, an electrode was formed. On top of this, Ta ₂ O ₅ having a thickness of 900 ° is formed as an inorganic insulating film by a sputtering method.
A coating type insulating film was formed with a thickness of 600 ° by printing and baking. Further, a polyimide alignment film having a thickness of 200 mm was formed by printing and firing.

A resist (“SPP-776”, manufactured by Toyo Gosei Kogyo Co., Ltd.) composed of a polyvinyl alcohol composition containing a photosensitizer is spin-coated only on one of the alignment films.
Prebaking was performed at 90 ° C. for 10 minutes. The resist film thickness after prebaking was set to 1.2 to 1.3 μm. To this resist, a UV pattern exposure of 365 nm was performed for 30 m.
J, and after forming the partition member by development with an ultrapure water shower, 9 to remove water remaining on the substrate.
Drying was performed at 0 ° C. for 5 minutes.

Rubbing treatment was applied to the alignment films of both substrates.
For rubbing, a roller wrapped with a Uganda-made cotton cloth was used at a rotational speed of 11.7 revolutions / sec and a substrate feed speed of 10 mm / sec, and the treatment was performed in one direction with two rollers in the same direction. Was. At this time, α-bromonaphthalene was dropped on the alignment film, and the contact angle of the droplet was measured, whereby the dispersion term of the surface energy of the alignment film was calculated. The dispersion term of the surface energy of this alignment film was periodically monitored, and was measured from 42.20 mN / m to 43.10 mN / m.
The rubbing strength was adjusted so as to be in between. The rubbing strength was adjusted by changing the amount of rubbing cloth pressed into the substrate. As a result, the pretilt of the alignment films on the upper and lower substrates could be stabilized at 16 to 18 degrees.

In the present invention, the above pretilt means a value measured by the following measuring method.

The pretilt angle α is measured by a crystal rotation method (Jpa.J. Appl. Phys. Vo).
l. 19 (1980) No. 10, Short Not
es2013). Further, as the liquid crystal for measuring the pretilt angle α, a ferroelectric liquid crystal (“CS-
1014 "), a mixture of compounds represented by the following structural formulas at a weight ratio of 20% was injected as a standard liquid crystal and measured.

[0032]

Embedded image

Incidentally, this mixed liquid crystal composition is 10-55.
At 0 ° C. showed a SmA phase.

The measurement procedure involves rotating a helium-neon laser beam having a polarization plane at an angle of 45 ° to the rotation axis while rotating the liquid crystal panel on a plane perpendicular to the upper and lower substrates and including an alignment processing axis (rubbing axis). Irradiation was performed from a direction perpendicular to the axis, and the transmitted light intensity was measured by a photodiode through a polarizing plate having a transmission axis parallel to the incident polarization plane on the opposite side. Then, a pretilt angle α was obtained by a simulation of fitting a theoretical curve to an equation shown below with respect to a transmitted light intensity spectrum generated by the interference.

[0035]

(Equation 1)

The bristles of the rubbing cloth adhered to the substrate in the rubbing treatment of the alignment film were washed with a mixed solution of IPA (isopropanol) and water, and IPA was spin-dried to finish.

After that, the average particle size of 1.sub.
25 μm glass spacers with a distribution density of 300 pieces / mm
² was spread, a sealing material was drawn on the peripheral edge of the other substrate, and the upper and lower substrates were bonded to face each other, and then heat-cured. The heating condition at this time was 160 ° C. for 1 hour.

The liquid crystal cell thus obtained is a ferroelectric liquid crystal having a spontaneous polarization value (Ps) of 40 nC / cm ^2.
When a pyrimidine-based chiral smectic liquid crystal was injected into a liquid crystal device, uniform and good alignment was obtained, and the driving characteristics were also very good. The spontaneous polarization value (Ps) is calculated according to K. Miyasato et al. "Direct measurement method of spontaneous polarization of ferroelectric liquid crystal by triangular wave" (Journal of Japan Society of Applied Physics,
22, No. 10 (661) 1983, "Direct M
etwith with TriangleWave
s for Measuring Spontaneo
us Polarization in Ferroel
electric LiquidCrystal ", as
desscribed by K. Miyasatoet
al. (Jap. J. Appl. Phys. 22.N
o. 10, L661 (1983))).

[Embodiment 2] In the step of forming the partition member in the embodiment 1, a 3 mm-wide partition line serving as a sealing material is added to the peripheral portion of the substrate at the time of resist pattern exposure, and heating is performed in the substrate bonding step. Conditions at 150 ° C for 1.5
A liquid crystal element was produced in the same manner as in Example 1 except that the time was changed.

As in the liquid crystal element of Example 1, the obtained liquid crystal element had uniform and good alignment and very good driving characteristics. Further, since the sealing material was formed by the partition line, the problem of elution of the ionic substance from the sealing material to the liquid crystal layer was eliminated, and good alignment was obtained over the entire pixel portion. Further, the cost can be reduced by omitting the sealing material drawing step.

[0041]

As described above, according to the present invention, the partition wall member is formed using a resist made of polyvinyl alcohol, and the upper and lower substrates are bonded to each other. Provided is a liquid crystal element in which abnormality in liquid crystal alignment and fluctuation in pretilt due to a component material forming component are suppressed, uniform and good alignment is stably obtained, driving characteristics are excellent, and high quality image display is possible. .

Further, by forming a partition line as a sealing material at the same time as forming the partition member, the sealing material drawing step can be omitted to reduce the cost, and at the same time, the liquid crystal using the ionic substance eluted from the conventional sealing material can be obtained. Can be provided, and a highly reliable and high quality liquid crystal element can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view of one embodiment of a liquid crystal element of the present invention.

[Explanation of symbols]

 11, 21 Substrate 12, 22 Electrode 13, 23 Inorganic insulating film 14, 24 Coating type insulating film 15, 25 Alignment film 16 Partition member 17 Spacer 18 Liquid crystal compound

Claims (10)

[Claims] 1. A liquid crystal element having a liquid crystal sandwiched between a pair of substrates each having an electrode, wherein said pair of substrates is a partition member made of a polyvinyl alcohol composition containing a photosensitive agent in a display section. A liquid crystal element characterized by being adhered by. 2. The color liquid crystal device according to claim 1, wherein each of said electrodes comprises a stripe-shaped electrode group, and is arranged so as to be orthogonal to each other, and said partition member is formed in an electrode gap on one substrate. 3. The color liquid crystal device according to claim 1, wherein said partition member is in a stripe shape. 4. The partition member according to claim 1, wherein the partition member has a dot shape.
Or a color liquid crystal element according to 2. 5. The liquid crystal device according to claim 1, wherein the liquid crystal is a chiral smectic liquid crystal. 6. The liquid crystal according to claim 5, wherein said liquid crystal is a ferroelectric liquid crystal.
The liquid crystal element according to the above. 7. The liquid crystal device according to claim 5, wherein the liquid crystal is an antiferroelectric liquid crystal. 8. The method for producing a liquid crystal element according to claim 1, wherein a polyvinyl alcohol composition containing a photosensitive agent is applied to one substrate surface, and after pattern exposure, is developed with water. A method of manufacturing a liquid crystal element, comprising forming a partition member on the substrate, laminating the other substrate, heating and curing the partition member, and bonding a pair of substrates. 9. The method for manufacturing a liquid crystal device according to claim 8, wherein an alignment film is formed on at least a substrate surface on which the partition member is provided, and after the partition member is formed on the alignment film, a rubbing treatment is performed on the alignment film surface. . 10. The liquid crystal device according to claim 8, wherein a partition member is also formed at a peripheral portion of the substrate when the partition portion is formed, and the partition member at the peripheral portion is a sealing material for containing liquid crystal. Production method.