JPS6162023A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To obtain an orientation control film forming liquid crystal showing a smectic phase of a uniform monodomain over the whole surface by using a specific orientation control film. CONSTITUTION:The orientation control film 3 consisting of an organic titanium compound and organic resin is formed on a plastic substrate 1 on which a transparent electrode 2 consisting of the liquid crystal has been already formed. Since the orientation control film can be formed by a dipping method or a blowing method and the film formation is suitable for continuous mass production, a liquid crystal display panel using a plastic panel for its substrate can be easily formed. Liquid crystal showing ferrodielectric property is preferable to smectic liquid crystal and a liquid crystal component having a chiral smectic phase e.g. can be used. When the ferrodielectric substance is used for the liquid crystal element, a response speed is extremely increased and the bistability of orientation of liquid crystal molecules is effectively obtained. Such a kind of cell structure generates optical modulation when a voltage is impressed between the electrodes 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal element used in a liquid crystal display element, a liquid crystal-light shutter, etc., particularly a liquid crystal element using a plastic substrate, and more specifically, by improving the initial alignment state of liquid crystal molecules. This invention relates to a liquid crystal element with improved display and driving characteristics.

Up until now, liquid crystal elements have mainly been M, 5Chadt, W, and H.
Written by eItriCh”Applied PhysjcsL
etters” Vol, 18. No. 4 (1971
, 2, 15).

P, 127-128 (7) “Voltage-De
pendentOptical Activity
of a TwistedNematie Liq
uid Crystal” as described in TN (
The Twisted Nematic (Twisted Nematic) method has been adopted, and as a method to efficiently ensure the alignment control of this TN method, the substrate interface in contact with the nematic liquid crystal is formed using SiO or 5i02 formed by oblique evaporation, or an organic resin rubbed on one side, e.g. A method of forming the film using polyimide or polyamide is known.

Display panels using this TN method do not have high-speed response or memory effects in the TN method itself, so a display panel with high pixel density is designed. requires an active matrix substrate. However, in active matrix drive type display panels using such TN liquid crystals, the TPT used has a complicated structure, so the number of units manufactured is as large as T, and the high manufacturing cost is a bottleneck. Another problem is that it is difficult to form a thin film semiconductor (eg, polysilicon, amorphous silicon) that constitutes the TPT over a wide area.

As a solution to these problems, N, A, C1a
rk and S, T, Lage r
A ferroelectric liquid crystal device proposed in U.S. Pat. No. 4,367,924 by W.A.I.

However, although ferroelectric liquid crystals exhibit their behavior in a chiral smectic phase, smectic phase liquid crystals generally have the drawback of poor alignment controllability and alignment stability compared to nematic phase liquid crystals. In experiments conducted by the present inventors, it has been found that by simply applying the orientation control properties known in the conventional TN method to the formation of a smectic phase, it is not possible to form a uniform monodomain smectic phase over the entire surface; It has been found that a uniform monodomain smectic phase can be formed by using a specific orientation control film.

Therefore, the object of the present invention is to obtain a uniform monodomain smectoid phase over the entire surface, particularly a chiral smectate C phase (SmC*) exhibiting ferroelectric properties.

H phase (SmH*), I phase (SmI book), F phase (SmF*
) or G phase (6 lines of 3 m) is provided.

Another object of the present invention is to provide an alignment control film suitable for a smectic liquid crystal device using a plastic substrate.

An object of the present invention is to provide a liquid crystal element having a cell structure in which a smectic liquid crystal is sealed between a pair of substrates provided with electrodes, in which at least one of the pair of substrates contains the organic titanium compound and the organic resin. This is achieved by a liquid crystal element having an alignment control film formed from a composition of

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows one embodiment of a liquid crystal element according to the present invention, in which l represents a plastic substrate.

2 is an electrode made of a transparent conductive film provided on the substrate; 3
is an alignment control film, 4 is a sealing member, 5 is a spacer member, 6
indicates a smectic liquid crystal material. plastic board l
Plastics such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, cellulose triacetate, polyol and polyether sulfone are used, and tin oxide is added to these by known means such as vapor deposition, low-temperature sputtering, CVD, etc. , indium oxide and ITO (Indium Ti
A transparent conductive material II@2 such as n Oxide) is provided.

An alignment control film 3 made of a composition as a component is formed.

As a 41-machine titanium compound, the general formula Ti(OR)4
(However, OR represents a hydroxy group, a carboxy group, or an alkoxy group) is preferable, and specifically, tetra-impropoxy titanium, tetra-n-butoxy titanium,
Tetrabis(2-ethylhexoxy)titanium, tetrastearoxytitanium, diisopropoxy-bis(acetylacetonato)titanium, di-n-butoxy-bis(
Examples include titanium (tosiliethanolaminate).

Various organic resins can be used, but in particular polyester resins, incyanate resins, polyamide resins, polyimide resins, polyesterimide resins,
Resins selected from resins such as polyamideimide resin, epoxy resin, and polyvinyl alcohol resin can be used.

Polyester resins are linear saturated polyesters, including terephthalic acid, isophthalic acid, adipic acid, sepacic acid,
Synthesized by using various catalysts and promoters with saturated polycarboxylic acids such as trimetic anhydride, saturated polyhydric alcohols such as ethylene glycol, propylene glycol, neopentyl glycol, and styrene monomers, methyl methacrylate, diallyl phthalate, etc. The saturated polyester or copolymer thereof is particularly preferably composed mainly of terephthalic acid and has a melting point Tm of 60'<Tm<150°C from the viewpoint of formation of an alignment control film, heat resistance, and reactivity.

Isocyane-1 resin is a resin in which a compound containing an incyane I group (-NGO) is contained alone or in combination with a hydroxyl group (-OH), an amino group (-Nl2), or a carboxyl group (-
It refers to a substance mixed with a substance that easily reacts with incyanate (COOH), and is characterized by high polarity and reactivity (incyanate ->1). For example, triphenylmethane triincyanate (trade name Desmodur)
R), tris (4-phenylisocyanate I.) thiophosphine I. (trade name: Desmodur RF), and TD (trade name)
Desmodur TT), TI) I trimer (trade name DesmodurIL), 2,4,4'-diphenyl ether triisocyanate (trade name Hylon)
DM), MDI (product name Coronate AP)
In addition, as a polyisocyanate, a reaction product of TDI and trimethylolpropane (trade name: Coronate) is used as a polyisocyanate.
L) and the like, and polyisocyanates are preferred from the viewpoint of toxicity, ease of handling, storage stability, and reactivity during formation of the alignment control film.

Polyamide resin is generally referred to as nylon, and its raw materials include, for example, caprolactam or 6-aminocaproic acid, which is the raw material for nylon 6, and hexamethylene diamine and adipic acid, which are the raw materials for nylon 66 and nylon 610. , dicarboxylic acids such as sepacic acid,
11-aminoundecanoic acid, a raw material for nylon 11,
Examples include W-laurolactam, a raw material for nylon 12, as well as bis(4-aminocyclohexyl)methane, metaxycleandiamine, or its hydride, piperazine, 2,5-dimethylpiperazine, and trimethylhexamethylenediamine. Also includes diamines such as. Particularly preferred are nylon 6/66 and nylon 6/6.

Examples of poxy resin include bisphenol A, 4,
4'-dihydroxybiphenyl, 2゜2'-bis(4-
Dehalogenation is achieved by reacting polyhydric phenols such as hydroxyphenylmethane and trihydroxydiphenyldimethylmethane with epihalohydrin (epichlorohydrin) or a compound that can be derived into epihalohydrin (dihalohydrino such as dichlorohydrin) under a basic or acidic catalyst. By reaction? I can do it. In addition, for example, "Epoxy Resin" (Synthetic Resin Industrial Technology 9, written by Shigeo Kiyono, published by Seibundo Shinkosha) and "Manufacture and Application of Epoxy Resin (Hiroaki Kakiuchi, published by Kobunshi Kagaku Kankai)" epoxy resins can be used.

The polyimide, polyesterimide, and polyamideimide used in the present invention are obtained by dissolving polyamic acid, which is a precursor thereof, in a solvent, applying the solution to the substrate-L, and then dehydrating and ring-closing the solution by heat treatment.

Polyamic acid, which is a precursor of polyamideimide, is synthesized by condensation of polygodimine obtained from excess diamine and dicarboxylic acid anhydride. Polyamic acid, which is a precursor of polyesterimide, is synthesized by condensation of a dicarboxylic anhydride having an ester group and a diamine. This dicarboxylic acid anhydride containing 41 ester groups is obtained from trimellitic acid and a diol. Moreover, polyamic acid, which is a precursor of polyimide, is obtained by condensation of dicarboxylic acid anhydride and diamine. As these representative dicarboxylic acid anhydrides and diamines, for example, U.S. Pat.
Those described in Japanese Patent No. 179634 can be used. Specifically, the diamines include m- or p-phenylenediamine, m- or p-xylenecyamine, 4,4'
-diaminodiphenyl ether and 4,4'-diaminediphenylmethane, and diols include hydroquinone, bisphenol A, dichlorobisphenol A
, tetrachlorobisphenol A. Examples of dicarboxylic anhydrides include pyromellitic anhydride, 2,3
, 6,7-naphthalenetetra or levonic acid anhydride.

When forming the alignment control film 3 using a coating solution containing organic titanium and IJki Yokozai, if the concentration of organic titanium and organic resin in the coating solution is too low, sufficient alignment performance cannot be obtained. If it is too high, undulation of the film formation, interference color of reflected light due to the refractive index, and an increase in the resistance value on the transparent conductive film will occur, so 1 to 10 wt% is preferable.

In preparing the coating solution, solvents used include alcoholic solvents such as methanol, ethanol, isopropyl alcohol, and butamel, acetones such as acetone and methyl ethyl ketone, cyclic ethers such as tetrahydrofuran and dioxane, methyl acetate, and acetic acid. Examples include esters such as ethyl.

These coating liquids can be applied to a substrate, particularly a plastic substrate, by a spinner coating method or a screen printing method, and then heated at 60° C. to 150° C. to form a film.

After film formation, cotton cloth ring 20-200 g/crn'
By rubbing under static pressure, preferably around 100 g/cm', an alignment control film is obtained, and a liquid crystal display panel is obtained by filling a liquid crystal material between the substrates.

The general thickness of this alignment control film 3 is 100 to 1 pL.
, preferably 500 to 2000 people.

Forming of the alignment control film of the liquid crystal display panel of the present invention can be easily carried out using a dipping method or a spraying method, and it is suitable for continuous mass production because it does not require a vacuum process, patterning (etching, peeling) process, or printing process. In addition, since a stable alignment control film can be obtained without requiring high temperatures for film formation, it has become possible to easily produce liquid crystal display panels using plastic films as substrates.

Further, the spacer member 5 is obtained by forming a film of photosensitive resin, for example, photosensitive polyimide, and then performing a predetermined photoetching process.

The smectic liquid crystal used in the present invention preferably exhibits ferroelectricity, such as SmC wood, SmH*,
A liquid crystal composition having a chiral smectate phase such as SmF*, SmF wood, or SmG* can be used.

Liquid crystals exhibiting a chiral smectoid phase used in the liquid crystal element of the present invention are shown below.

(1)
CH3-methylbutylcinnamate (DOBAMB
C)-Chlorpropylcinname-1-()(OBACP
C)-Methylbutyl-α-cyanosinname I (DO
BAMBCC) / U U 3 mH / D 'U
monomethylbutyl-α-cyanocinnamate (TDOBA)
MBCC)-methylbutyl-α-chlorocinnamate (
OOBAMBCC)-Methylbutyl-α-methylcinnamate CH30 -C00CH2CHC2H5 Ne4.4'-Azoxycinnamic acid-bis(2-
methylbutyl) ester H 4-0-(2-methyl)-butylresolsiliten-4'
-Octylaniline (MBRA 8) These liquid crystals may be used alone or in combination of two or more,
Alternatively, it may be combined with other smectate liquid crystals or cholesteric (chiral nematic) liquid crystals.

FIG. 2 schematically depicts an example of a cell for explaining the operation of a ferroelectric liquid crystal. 11 and 11' are I n
203.5n02 or ITO (Indium T
SmC' is a substrate (glass plate) coated with a transparent electrode made of a thin film such as SmC' (in Oxide), between which a liquid crystal molecular layer 12 is oriented perpendicular to the glass surface.

Trees such as SmH, SmF, SmI*SmG'
Enclosed is a wood chiral smectic phase liquid crystal. A thick line 13 represents a liquid crystal molecule, and this liquid crystal molecule 13 has a dipole moment in the direction perpendicular to the molecule)
(P soil) has 14. Substrates 11 and 11'-):
When a voltage higher than a certain threshold is applied between the electrodes, the helical structure of the liquid crystal molecules 13 is unraveled, and the dipole moment (P
The alignment direction of the liquid crystal molecules 13 can be changed so that all of the liquid crystal molecules (±) 14 are oriented in the direction of the electric field. The liquid crystal molecules 13 have an elongated shape and exhibit refractive index anisotropy in the long axis direction and the short axis direction. Therefore, for example, if a crossed Nicol polarizer is placed above and below the glass surface, a voltage can be applied. It is easily understood that the liquid crystal optical modulator is a liquid crystal optical modulator whose optical characteristics change depending on the polarity.

The liquid crystal cell preferably used in the liquid crystal element of the present invention can have a sufficiently thin thickness (for example, 10° or less). As the liquid crystal layer becomes thinner, the helical structure of the liquid crystal molecules unwinds and becomes a non-helical structure even when no electric field is applied, as shown in Figure 3, and the dipole moment) P or P' becomes The state is either upward (24) or downward (24'). When such a cell is applied with an electric field E or E' having a different polarity above a certain dark value using the voltage applying means 21 and 21' as shown in FIG. 3, the dipole moment I. Corresponding to the electric field vector of E', the direction changes to -1- direction 24 or downward direction 24', and accordingly, the liquid crystal molecules enter the first stable state 23.
or the second stable state 23'.

As mentioned earlier, there are two advantages to using such ferroelectricity as a liquid crystal element.

The first is that the response speed is extremely fast, and the second is that the alignment of liquid crystal molecules has bistability. To further explain the second point, for example, with reference to FIG. 2, when an electric field E is applied, the liquid crystal molecules are oriented in a first stable state 23, and this state remains stable even when the electric field is turned off. Furthermore, when an opposite electric field E' is applied, the liquid crystal molecules enter a second stable state 23.
', and changes the orientation of the molecule, but it remains in this state even when the electric field is turned off.

Further, as long as the electric field E that is generated does not exceed a certain threshold value, each orientation state is maintained. In order to effectively realize such fast response speed and bistability, it is preferable that the cell be as thin as possible.

The biggest problem in forming devices using liquid crystals with such ferroelectricity is, as mentioned earlier, that SmC
, SmH tree, SmF tree.

Motoki: It is difficult to form a highly monodomain cell in which a layer with a chiral smectic phase such as SmI or SmG is aligned perpendicular to the substrate surface and liquid crystal molecules are aligned approximately parallel to the substrate surface. This is the main objective of the present invention to provide a solution to this problem.

FIGS. 4(A) and 4(B) show an embodiment of the liquid crystal element of the present invention. FIG. 4(A) is a plan view of the liquid crystal element of the present invention, and FIG. 4(CB) is a sectional view taken along line AA'.

In the cell structure 100 shown in FIG. 4, a pair of glass plates or plastic substrates 101 (only the OL'LH side may be a plastic substrate) are held at a predetermined distance by spacers 104, and this pair of substrates is It has a cell structure adhered with an adhesive 106 for sealing, and furthermore, on the substrate lO1 is an electrode group consisting of a plurality of transparent electrodes 102 (for example, an electrode group for applying a scanning voltage in a matrix electrode structure). is formed in a predetermined pattern such as a strip pattern.

On the substrate 101', an electrode group (for example,
Of the matrix electrode structure, a signal voltage application electrode group) is formed.

An alignment control film 105 formed from a coating liquid containing the above-mentioned organic titanium compound and organic resin is provided on the substrate 101 and -In of t o t', respectively.

Liquid crystal layer in the cell structure 100 shown in FIG. 4*
*103 is SmC, SmH, SmF tree.

Chiral smecti books such as SmI and SmC trees It can be a phase.

FIG. 5 shows another specific example of the liquid crystal element of the present invention. In the liquid crystal element shown in FIG. 5, a plurality of spacer members 201 are arranged between a pair of plastic substrates 101 and 101'.

For example, this spacer member 201 is made of SiO, 5i02
．． A203, inorganic compounds such as TiO2, or polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparagisilylene, polyester, polycarbonate-1, polyvinyl acetal,
Polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, Yurya resin,
It can be obtained by forming a film of resin such as acrylic resin or photoresist resin by an appropriate method, and then etching it so that the spacer member 203 is placed at a predetermined position.

In such a cell structure lOO, polarizers 107 and 108 in a crossed nicol state or a parallel nicol state are arranged on both sides of the substrates lot and 101', respectively, and the electrode 1
Optical modulation will occur when a voltage is applied between 02 and 102'.

The present invention will be described in detail below based on Examples, but the present invention is not limited to the following Examples unless the gist of the invention is exceeded.

Example 1 A solution having the following composition (solution composition (1) ) was applied and dried at 120°C for 30 minutes to form a thin film.

Tetra-isopropoxy titanium 1g Polyester resin (Toyobo; Byron 30p) 0.5g Tetrahydrofuran 10m methyl ethyl ketone 90m ethanol
20m sentence, 100g/crn
The rubbed plastic substrates were rubbed in one direction under pressure, and the rubbed plastic substrates were placed one on top of the other so that the rubbing directions at the bottom were parallel to each other, and the periphery except for the area that would become the injection port was sealed. At this time, the distance between the pair of plastic substrates was 1-.

Next, P-decyloxybenzylidene-P'-amino-2-
A liquid crystal composition was prepared by adding 5 parts by weight of cholesteryl nonanate to 100 parts by weight of methyl butyl cinnamate (DOBAMBC).

This liquid crystal composition was heated to form the isokyoshi phase, prepared as above, and injected into the cell through the injection port under reduced pressure, and the injection port was sealed. The temperature of this cell was lowered by slow cooling to about 70℃.
When a pair of polarizers were provided in a crossed nicol state while the film was maintained at 'C' and then observed under a microscope, it was confirmed that a monodomain non-helical structure of SinC* was formed.

Examples 2 to 5 Liquid crystal devices were produced in the same manner as in Example 1, except that the coating liquids having the following solution compositions (2) to (5) used in Example 1 were used.

Sputum Makoto 2 (Example 2) Tetra-isopropoxy titanium 1g Incyanate resin 0.5g (Japan Polyurethane, Coronel L) (solid content) Tetrahydrofuran
10m sentence methyl ethyl ketone
90m ethyl acetate 7m
Bun ethanol 20m Bun 3 (
Example 3) Tetra-impropoxy titanium 1g polyamide resin 0.5g (Toshi, 0M400
0) Isopropyl alcohol 10mM methyl ethyl ketone 90m ethanol
20m sentence 4 (Example 4) Tetraimprobogisi titanium Ig Ebony resin 0.5g (Shell Chemical, Epicor 1-836) Tetrahydrofuran
lom methyl ethyl keto 7 90m ethanol 20m 5 (Example 5) Tetra-impropoxy titanium 1g polyvinyl alcohol resin 0.5g isopropyl alcohol 20mM tetrahydrofuran
50m sentence methyl ethyl ketone
30mM ethanol 20m
When these liquid crystal cells were measured in the same manner as in Example 1, a uniform monodomain non-helical structure was similarly observed.

Example 6-i.

Instead of the organic titanium compound used in Example 1, tetra-
Normal butoxy titanium (Example 6), tetrabis (2
-Ethylhexoxytitanium (Example 7), tetrastearoxytitanium (Example 8), diisopropoxy-bis(
acetylacetonato) titanium (Example 9), di-n-n-butoxy-bis(triethanolaminate) titanium (Example 10) Example 11 Striped I with a pitch of 1100p and a width of 62.5 gm
A coating solution having the following solution composition (6) was applied using a spinner onto a glass plate provided with a TO film as an electrode.

Solution composition (6) Tetra-isopropoxy titanium 1g Condensation product of pyronolitic anhydride, a precursor of polyimide, and 4,4'-diaminodiphenyl ether 0.5g Product (polyamic acid) (Solid content) Isopropylar 50m ethanol
50m sentence methyl ethyl ketone
2 glass plates coated with this solution composition (6)
A polyimide film was formed by a dehydration ring closure reaction by heating at 30°C for about 1 hour.

Next, the rubbed glass plates are rubbed in one direction under pressure of "long/crn", and the rubbed glass plates are stacked so that the lower rubbing directions are parallel to each other, and the surrounding area excluding the part that will become the injection port. was sealed. The distance between the pair of glass substrates at this time was 1=. Next, a liquid crystal cell was prepared in the same manner as in Example 1, and when observed, it was found that SmC* with a monodomy non-helical structure was formed.

Examples 12 to 13 Instead of the condensation product that is a precursor of polyimide used in Example 11, aromatic dicarboxylic anhydride obtained from trimellitic acid and hydroquinone, which are precursors of polyesterimide, and 4.4 Condensation product (polyamic acid) with '-diaminodiphenyl ether (Example 12), condensation product of N,N'-bis(3-aminophenyl)inphthalamide, a precursor of polyamideimide, and pyromellitic anhydride A liquid crystal cell was prepared in the same manner as in Example 11 except that polyamic acid (polyamic acid) (Example 13) was used, and when observed, similar results were obtained.

Example 14 Example 11 except that tetra-n-butoxytitanium was used instead of the organic titanium compound used in Example 11.
When a liquid crystal element was produced in the same manner as above, a non-helical structure S m C* was formed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the liquid crystal element of the present invention. 2 and 3 are perspective views showing a liquid crystal cell used in the present invention. FIG. 4(A) is a plan view showing the liquid crystal element of the present invention, and FIG. 4(B) is a sectional view taken along line AA'. FIG. 5 is a sectional view showing another specific example of the liquid crystal element of the present invention. l; Plastic substrate 2; Transparent conductive film electrode 3; Alignment control film 4; Seal member 5; Spacer member 6; Smectic liquid crystal 100, cell structure 101.101', substrate 102.102', electrode 103, liquid crystal layer 104 .201, spacer member 105,
Orientation control film 106, adhesive (sealing member) 107, 108
; Polarizer 109, heating element 7

Claims (7)

[Claims] (1) In a liquid crystal element having a cell structure in which a smectic liquid crystal is sealed between a pair of substrates provided with electrodes, at least one of the pair of substrates is formed from a composition containing an organic titanium compound and an organic resin. A liquid crystal element comprising an alignment control film. (2) The liquid crystal device according to claim 1, wherein the smectic liquid crystal is a ferroelectric liquid crystal. (3) The liquid crystal device according to claim 2, wherein the ferroelectric liquid crystal is a chiral smect liquid crystal. (4) The liquid crystal device according to claim 3, wherein the chiral smect liquid crystal forms a phase with a non-helical structure. (5) The chiral smectate liquid crystal has a C phase, an H phase,
The liquid crystal element according to claim 3 or 4, which is in I phase, F phase, or G phase. (6) The organic resin is a resin selected from at least one resin selected from the group consisting of polyester resin, isocyanate resin, polyamide resin, polyimide resin, polyesterimide resin, polyamideimide resin, epoxy resin, and polyvinyl alcohol resin. The liquid crystal element according to range 1. (7) The liquid crystal device according to claim 1, wherein at least one of the pair of substrates is a plastic substrate.