JPH0769544B2 - Composition for coating liquid crystal element and liquid crystal element alignment film - Google Patents

Description

TECHNICAL FIELD The present invention relates to an alignment film used for an electro-optical element such as a display panel and a liquid crystal shutter using liquid crystal. More specifically, it relates to an alignment film having excellent liquid crystal alignment and a coating composition suitable for the alignment film.

[Prior Art] Conventionally, ordinary polymers are characterized by their high insulation resistance and breakdown electric field, and are used for various purposes and purposes in electronic devices. In that case, since heat resistance is often required, polyimide, polyamideimide, polyphenylene oxide, polysulfone and the like have been put into practical use.

Of these, polyimide is currently the most reliable and most frequently used. Polyimide is widely used in the semiconductor field as a multilayer wiring insulation film, a surface protection film, a soft error prevention film, etc., and as an alignment film for liquid crystal elements (JP-A-57-56817 and JP-A-60-60). 230635, etc.).

As for the coating material used for the liquid crystal alignment film, the alignment performance of the liquid crystal is important especially in terms of device function. Polyimide is a suitable material as a liquid crystal alignment film from the viewpoint of heat resistance, adhesiveness, insulation, film forming property, etc., but it cannot be said to be a satisfactory material in terms of liquid crystal alignment performance. In particular, for ferroelectric liquid crystal displays that are currently being developed as next-generation liquid crystal displays, the liquid crystal molecules must have a molecular arrangement similar to a crystal called chiral smectic C ^* , and even if polyimide is used as an alignment film. It is extremely difficult to form a satisfactory orientation state. Therefore, an alignment film for a ferroelectric liquid crystal display, which is mainly composed of modification of polyimide, is currently being developed (JP-A-62-87939, JP-A-62-98327, etc.).

However, since polyimide forms a high molecular weight film by the reaction between an amine and a carboxylic acid derivative, free ionic groups such as amine and carboxylic acid remain in the formed film if the reaction does not proceed completely. Therefore, it has a drawback that it tends to interfere with the stable alignment of liquid crystal molecules.

[Problems to be Solved by the Invention] In order to improve the above-mentioned problems of the prior art, the present invention uses a special polymer having a rigid main chain and a rod-shaped structure (rigid structure) to control the alignment, particularly the contrast of liquid crystal. A first object is to provide an alignment film having a high ratio and an excellent response speed.

The second object relates to a coating material useful for an alignment film of liquid crystal, and provides a coating composition which can easily form a film having a uniform thickness by various film forming methods.

[Means for Solving the Problems] To achieve the above object, the present invention has the following constitution.

“1. In a liquid crystal device including at least a pair of electrode substrates, an alignment film and a liquid crystal, the viscosity index α of the formula represented by the following [I] is at least one organic solvent and temperature in the process of forming the alignment film. A liquid crystal device comprising a polymer having a value of 0.85 or more under conditions and having a surface tension in the range of 8 to 35 dyn / cm.

[Η] = K · M ^α [I] (In the formula [I], [η] is the intrinsic viscosity in the solution viscosity measurement method of the polymer, K is a constant, M is the molecular weight, and α is the viscosity index.) 2 In a liquid crystal element that is composed of at least a pair of electrode substrates, an alignment film, and a liquid crystal, the alignment film is made of a polymer containing at least a polyfumarate ester or a copolymer thereof represented by the following general formula [II]. And liquid crystal element.

(In the formula, R ¹ and R ² are the same or different groups, and are at least one selected from a linear or branched alkyl group, a cycloalkyl group, a halogenated alkyl group, a silalkyl group, and a siloxanylalkyl group. 3. A coating composition for an alignment film of a liquid crystal device including a pair of electrode substrates, an alignment film and a liquid crystal, wherein the composition is polyfumaric acid represented by the following general formula [II]: A coating composition for a liquid crystal device alignment film, comprising a polymer containing at least an ester or a copolymer thereof and a halogen-containing organic solvent.

(In the formula, R ¹ and R ² are the same or different groups, and are at least one selected from a linear or branched alkyl group, a cycloalkyl group, a halogenated alkyl group, a silalkyl group, and a siloxanylalkyl group. The organic group of is shown below.) ”First, the first invention will be described.

In the present invention, the fact that the viscosity index α is 0.85 or more indicates that the polymer main chain is rigid and has a rod-like structure. The preferable viscosity index α is 0.90 or more, and particularly preferably 0.95 or more. Here, the viscosity index α refers to that under at least one organic solvent and temperature conditions in the process of forming the alignment film. The process of forming the alignment film here means a time when the alignment state of the molecules of the alignment film is determined. In the actual process, generally,
The prepared alignment film forming solution is applied to a substrate or the like, and the alignment film is formed through a step of evaporating the solvent at room temperature or, if necessary, heated to accelerate evaporation. Therefore, depending on those cases, the temperature condition may be the solution temperature at the moment of application, if not heated, and the heating temperature when heated to evaporate the solvent. Alternatively, if there is a temperature change, it may be a temperature in the middle of the process.

The event of such a change process can be similarly applied to the solvent. That is, this is the case when the solvent composition may change in the course of the mixed solvent.

These conditions satisfy the conditions of the first invention of the present application by determining the temperature / solvent required from the conditions for forming the alignment film and measuring the viscosity index α of various polymers under the temperature / solvent conditions. It is possible to determine a polymer having a viscosity index α, or to measure the viscosity index α of a polymer at various temperature / solvent conditions to obtain the viscosity index α of the condition of the first invention of the present application. It is also possible to determine the temperature / solvent conditions to be obtained and freely form the alignment film according to the temperature / solvent conditions.

In the present invention, the viscosity index is the following Mark-Houwink-Sakurad
a is defined by the formula [I].

[Η] = K · M ^α [I] (In the formula [I], [η] is the intrinsic viscosity in the polymer solution viscosity measurement method, K is a constant, M is the molecular weight, and α is the viscosity index.) The method for obtaining the intrinsic viscosity [η] in the invention is according to a conventional method.
That is, first, the viscosity-molecular weight relational expression is obtained in advance. Next, using a Ostwald-type or Ubbelohde-type viscometer, the flow-down time of the dilute polymer solution is measured, and the relative viscosity (η _rel ) is determined by the following equation.

η _rel = t / t ₀ Here, t ₀ is the flow time of the pure solvent, and t is the flow time of the dilute solution of the polymer. Next, the specific viscosity (η _sp ) is calculated by the following equation.

η _sp = η _rel −1 Furthermore, the reduced viscosity (η _red ) is the specific viscosity per unit concentration and is calculated by the following equation.

η _red = η _sp / c (c is the polymer concentration) The intrinsic viscosity [η] is the reduced viscosity extrapolated to c = 0.

Experimentally, by determining the viscosity at several concentrations, c
The intrinsic viscosity extrapolated to = 0 is obtained.

The constant K and the viscosity index α are obtained by plotting log [η] and logMn or logMw.

log [η] = logK + αlogM However, in order to plot the above equation, it is necessary to determine the molecular weight (Mn or Mw) by osmotic pressure, light scattering, centrifugal sedimentation, etc.

It has also been theoretically proved that the polymer has a rod-like structure when the viscosity index α is 0.85 or more, preferably 0.95 or more. In particular, a polymer having a large (bulky) substituent in the side chain is constrained in the free rotation of the main chain and inevitably tends to have a rod-like structure. And it is so far difficult to clarify the theoretical reason why such a polymer is excellent in the orientation of liquid crystal, but when the polymer main chain has a rod-like structure, the polymer itself is easily oriented in a certain direction, It is considered that this is because the liquid crystal is easily aligned along the alignment direction.

The polymer having a viscosity index α of 0.85 or more used in the present invention may be any polymer, but is preferably a polyfumarate ester such as a homopolymer or copolymer of a fumarate ester, or a derivative thereof, and a poly Substituted acetylene, for example, homopolymer or copolymer of substituted acetylene, or a derivative thereof.

In the present invention, the ester group of the polyfumaric acid ester is not particularly limited, but a linear or branched alkyl group having 3 or more carbon atoms is preferable. The two ester groups of fumaric acid may be the same or different. In particular, the ester has a secondary alkyl group such as isopropyl, cyclohexyl and cyclopentyl, and te
Those having a tertiary alkyl group such as rt-butyl and tert-pentyl are preferable because a high molecular weight polymer can be obtained.

The viscosity index α of polyfumaric acid ester is reported to be 0.98 for diisopropyl polyfumarate (Otsu et al., Polymer Preprints Japan, 32 , 1039 (198
In the case of 3)), in which the ester group is further bulky and the rigidity of the molecule is increased, it is considered that the α value is further increased.

Furthermore, in the present invention, the polysubstituted acetylene is not particularly limited, but as the homopolymer of the substituted acetylene, poly (1-trimerylsilyl-1-propyl), poly (tert-butylacetylene), poly ( 2-octyne), poly (1-chloro-2-phenylacetylene), poly (1-phenyl-1-propyne) and the like are preferable.

Values of 0.89 to 1.07 have been reported for the viscosity index α of these polymers (Masuda et al., Polymer Preprints, Japa.
n, 33 , 66 (1984)).

Since these polymers usually have a heat resistance of 180 ° C or higher, when used as an alignment film for liquid crystals, decomposition or deterioration does not easily occur even if the injection of liquid crystal or the adhesion of spacers is performed at a high temperature. Excellent as a film.

All of these polymers have been found in recent years, and are available, for example, by the production methods shown below.

Polyfumaric acid ester is formed as a high molecular weight semi-flexible polymer by homopolymerization etc. because the polymerizability increases as the ester group of the monomer becomes bulky (Otsu et al., Makr
omol.Chem., Rapid Commun., 2 , 725 (1981), Otsu et al.,
ibid, 2 79, 729 (1981)).

Polysubstituted acetylene is homopolymerized with a transition metal catalyst to obtain a high molecular weight rigid polymer [Masuda et al., Acc.
Chem. Res., 17 , 51 (1984)].

In the above, the term "derivative" means not only a polymer derived from the above polymer by a reaction, but also a polymer obtained by modifying the polymer by heat treatment or the like. Tobacco Polyfumaric acid tert
-In the case of butyl, after applying to the substrate, heat treatment at high temperature,
For example, a part or all of the tert-butyl group of the side chain may be carboxylic acid. Further, it includes those obtained by performing surface treatment with plasma or the like for surface modification after forming the alignment film. In addition, copolymers are also included.

Other polymers that can be used as the alignment film of the present invention include poly N-substituted maleimides and poly N, N, N ', N'.
-Polyfumarate-like polymers such as tetraalkyl fumaramide, poly (benzyl acrylate), ori [1- (N-carbethoxy-phenyl)-
Methacrylicamide], poly (vinyl sulphate), poly (p-diethylphosphono-methylstyrene-costyrene), poly (methylmethacrylate-co-p-isopropylstyrene), poly [(butylimino) carbonyl] [poly (butylisocyanate) )], Poly (1-
Isobutyl-3-phenylsilsesquioxane), poly (3-methylbutenesilsesquioxane), poly (phenylsilsesquioxane) and the like.

Further, from the viewpoint of achieving uniform alignment of liquid crystal molecules, it is important for the ferroelectric liquid crystal device to achieve bistability of the device, especially in the ferroelectric liquid crystal device, because the interaction with the polar part of the liquid crystal molecule does not work so much. From this point, in the present invention, the surface tension of the polymer forming the liquid crystal alignment film is in the range of 8 to 35 dyn / cm, which is lower than that of the conventional polyimide. In this respect, vinyl chloride has a viscosity index α of about 0.85 but a surface tension of 41.9 dyn / cm (Polymer Handbook
3rd Edition, page IV / 415, John Wiley & Sons (198
According to 9)), it is unsuitable as a polymer used in the present invention. Further, this also works well for high pretilt of liquid crystal molecules (increasing the pretilt angle) which is important for improving display quality in the SBE type liquid crystal element. In the present invention, as the surface tension of the polymer, the Zisman plot (Zisma
n, et al., J. Colled Sci., 7 , 428 (1952)) and the values of critical surface tension and literature (Owens, et. al., J. Appl. Polymer
Sci., 13, 1711 (1969): Kaelble, et al., J. Adhesion, 2,
50 (1970): Hata et al., Journal of Japan Adhesion Society, 8, No.3, 131 141
(1972): Panzer, J. Colloid Sci., 44, 142 (1973)) and the like, the value obtained from the extended Fowkes equation described in is used.

As a means for obtaining the alignment film, any known means such as a dipping method, a spin coating method, a printing method, a water surface spreading method, and a Langmuir-Brogit method (LB method) can be adopted. In this case, any solvent may be used as long as the polymer is soluble.

Polyfumaric acid ester and poly-substituted acetylene, which are preferred polymers in the present invention, are soluble in general organic solvents such as benzene and chloroform, and do not require cyclization by heat condensation at high temperature like conventional polyimides, It can be easily applied to a plastic substrate, which is inferior in heat resistance to glass and the like, and is also suitable. It is also excellent in energy saving.

Next, the second and third inventions will be described.

In the present invention, the polyfumaric acid esters are A polymer mainly having the basic structure of, such as a polyfumarate ester, a copolymer, or a polymer blended with another polymer.

Tertiary-butyl, cyclohexyl, fumaric acid ester having a bulky substituent such as isopropyl radical polymerization to give a homopolymer or a copolymer, West German Patent No. 1,176,871, JP, West German Patent No. 1,520,702. Reported by F. Engelhardt et al. In recent years, Otsu et al., Mentioned above, have studied the polymerization of more fumaric acid esters. (T.Otsu,
N.Toyoda, Macromal.Chem., Rapid Commun., 2,725 (198
1), 2, 79 (1981), etc.). Then, it was clarified that the fumarate ester was homopolymerized into a high molecular weight polymer, which was poor in flexibility and was excellent in heat resistance due to its rigidity.

In the present invention, the ester group of orifumaric acid ester
As R ¹ and R ² , at least one organic group selected from a linear or branched alkyl group, a cycloalkyl group, a halogenated alkyl group, a silalkyl group, and a siloxanylalkyl group is required. Lower the surface energy,
This is to improve the alignment of the liquid crystal. Further, R ¹ and R ² in the general formula [II] are the same or different groups, at least one of which is selected from a secondary alkyl group having 3 to 9 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms. What is given is especially preferable since it imparts high heat resistance of 200 ° C. or higher. Further, those in which at least one of R ¹ and R ² is a fluorine-substituted alkyl group are particularly preferable for imparting a low surface energy of 25 dyn / cm or less. Specific examples of the fluorine-substituted alkyl group, 2,2,2-trifluoroethyl group,
2,2,2-trifluoro-1-trifluoromethylethyl group, 3,3,4,4,4-pentafluorobutyl group, 3,3,4,4,5
5,6,6,6-nonafluorohexyl group, 1,1,2,2-tetrahydroperfluorooctyl group, 1,1,2,2-tetrahydroperfluorodecyl group and the like, but are not particularly limited to these. Not something. Further, R ¹ and R ² are those having a secondary alkyl group such as isopropyl, cyclohexyl, and cyclopentyl, and those having a tertiary alkyl group such as tert-butyl and tert-pentyl are high molecular weight polymers. Is preferable.

Further, from the viewpoint of achieving uniform alignment of liquid crystal molecules, the surface tension of polyfumaric acid ester is lower than that of a conventional polyimide, such as 8 to 40 dyn, as described above in the description of the first invention. It is preferably within the range of / cm.

Further, the comonomer for obtaining the copolymer of polyfumaric acid ester is not particularly limited,
An electron-donating monomer such as vinyl acetate or styrene is particularly preferable because it easily forms a copolymer.

The method for producing the polyfumaric acid ester is not particularly limited and may be radical polymerization of the fumaric acid ester, or Otsu et al., Polymer Bulletin, 11 , 453.
As described in (1984), a polymerization method involving isomerization of maleic acid esters may be used.

Since these polymers usually have a heat resistance of 180 ° C. or higher, when they are used as a liquid crystal alignment film, they are unlikely to be decomposed or deteriorated even when the injection of liquid crystal and the adhesion of spacers are performed at high temperature. Further, unlike polyimide, there is almost no possibility that free ionic groups will be generated in the coating film, so that stable alignment of liquid crystal molecules can be maintained for a long time even when used as a liquid crystal element.

In the present invention, the halogen-containing organic solvent is a solvent that dissolves the polyfumaric acid esters at room temperature or under heating to form a uniform solution, and is not particularly limited as long as it contains halogen in the solvent molecule. However, chlorine-containing organic solvents and fluorine-containing organic solvents are preferable from the viewpoint of solvent stability.
For example, as the chlorine-containing organic solvent, chlorinated aliphatic hydrocarbons such as chloroform, methylene chloride, trichloroethylene, 1,1,2,2-tetrachloroethane, 1-chloronaphthalene, 1,2,4-trichlorobenzene, etc. Chlorinated aromatic hydrocarbons and the like are preferable. Further, as the fluorine-containing organic solvent, fluorocarbons such as 1,1,3-trichlorotrifluoroethane and tetrachlorodifluoroethane, 2,2,2-trifluoroethanol, 1H, 1
H, 3H-tetrafluoro-1-propanol, 1H, 1H, 5
H-octafluoro-1-pentanol, 1H, 1H, 7H-
Fluorine-containing alcohols such as dodecafluoro-1-heptanol and fluorine-containing esters such as ethyl trifluoroacetate are preferable. Among these, fluorinated alcohol is
It is particularly preferable from the viewpoint of ease of handling such as selecting the boiling point of the solvent having good wettability to the substrate in a wide range.

Polyfumaric acid esters are difficult to prepare a highly viscous solution by forming a gel when dissolved in ketones or ethers at a high concentration, but in these halogen-containing solvents, polyfumaric acid esters are 0.1% by weight or more. It is possible to easily and uniformly dissolve from a low concentration to a high concentration of 30% by weight or less to prepare a low-viscosity to high-viscosity solution. Furthermore, even if the concentration exceeds 30% by weight, it can be used by selecting the conditions.

In addition, the coating composition according to the present invention has a low surface tension, is excellent in wettability to the substrate for coating the surface of the substrate, and has a uniform and large-area coating film without defects such as pinholes. Can be formed over.

In the present invention, any component may be included in addition to the components described in the present invention. For example, other polymers may be blended for the purpose of improving the physical properties of the surface or imparting a function, or a silane coupling agent or the like may be blended for improving the adhesiveness to the substrate. In addition, additives such as antioxidants and surfactants may be included.

The method for forming a coating film using the coating composition of the present invention is not particularly limited. Generally, brush coating method, cast coating method, dip coating method, spin coating method,
A uniform film can be formed by a simple operation such as a water surface spreading method, an LB method, or a printing method. At this time, it is desirable to appropriately select the optimum composition of the coating liquid, such as the viscosity and the solvent, depending on the coating method to be used and the film thickness to be formed. With the composition of the present invention, a wide range of coating methods can be obtained. Adaptation is possible. Further, the solvent drying means and the drying temperature after the above coating operation are not particularly limited.

The polyfumaric acid ester used in the present invention does not require cyclization by heat condensation at high temperature unlike conventional polyimides, and therefore can be easily applied to a plastic substrate having poor heat resistance, and the process can be simplified. It will be

The film thickness of the film formed by using the coating composition of the present invention varies depending on the coating method, but from a monomolecular film by the LB method to 1 μm by the cast coating method.
It is possible to form a coating film having a wide range of film thicknesses up to the film thickness of m or more.

There is no particular limitation on the various post-treatments performed on the film formed using the coating composition of the present invention. For example, after the coating is formed, the polyfumaric acid ester main chain in the coating can be densely packed by heat treatment in a high temperature atmosphere. The heat treatment conditions are not particularly limited, but 130 to 2
Heat treatment at 40 ° C. for about 10 to 180 minutes is particularly preferable. In addition, when used as an alignment film of a liquid crystal element, rubbing treatment (known treatment means of rubbing in a certain direction with a cloth or a brush)
It is preferable that the alignment treatment such as Furthermore, in the case of tert-butyl polyfumarate as the polyfumaric acid ester, the te
Some or all of the rt-butyl groups can be carboxylic acids. For such treatment, at 180-250 ° C, 10
The heat treatment for about 1 to 180 minutes is particularly preferable.

The properties expected as a liquid crystal alignment film formed using the coating composition of the present invention are, for example, as follows.

(A) Alignment performance of liquid crystal molecules is good.

(B) Good adhesion to the substrate.

(C) Small hygroscopicity.

(D) Low moisture permeability.

(E) Great dielectric property.

(F) Good chemical resistance.

(G) Good heat resistance.

(H) Good rubbing performance.

(I) It is a low ionic impurity.

(J) High withstand voltage property (property of not breaking even when high voltage is applied)
To be.

(K) Good transparency.

The film formed by using the coating composition of the present invention is superior to polyimides conventionally used as liquid crystal alignment films in terms of (A), (C), (I), (K), etc. However, there are no other items that pose a problem in practical use. In particular, for ferroelectric liquid crystal displays that are currently being developed as next-generation liquid crystal displays, the liquid crystal molecules are chiral smectic C ^*.
That is, it is extremely difficult to form a satisfactory alignment state even if polyimide is used as an alignment film, because a molecular arrangement close to that of a crystal must be obtained. However, according to the film formed using the coating composition of the present invention, In addition, the uniformity of orientation, contrast, response speed, and the like, which are important for a display, can exhibit higher performance than that of polyimide. Also, as a coating film of polyfumaric acid ester, the composition according to the present invention exhibits excellent characteristics as a liquid crystal alignment film, as compared with the composition using a halogen-free organic solvent such as toluene.

The reason why the film formed using the coating composition of the present invention exhibits excellent properties as a liquid crystal alignment film as compared with a composition using a halogen-free organic solvent such as toluene is that the macanism of alignment of liquid crystal molecules is used. However, it is not clear that the film formed by the wide angle X-ray analysis of the formed film has a denser packing of the polymer main chain in the film formed by the chloroform solution as compared with the film formed by the toluene solution. It is considered that this is suitable for the alignment of liquid crystal molecules.

The surface energy of the coating film formed using the coating composition of the present invention varies depending on the type of the polyfumaric acid ester used, but since the bulky alkyl group covers the main chain, the critical surface tension is generally 35 dyn / cm. The following low energy surfaces are formed. Conventionally, such a low-energy surface can be formed by a fluoropolymer, etc., but few polymers are soluble in a wide range of solvents and have heat resistance of 180 ° C. or higher. Therefore, the coating composition of the present invention can provide a wide range of applications from the viewpoint that a coating film having a low surface energy can be easily formed.

The above-mentioned polymer having a rod-shaped structure of the present invention may be used alone or in combination.

Further, any component may be contained as long as it contains the polymer of the present invention. For example, conventionally used polyimide, polyester, polyamide, aramid or the like may be blended. You may make it a multilayer structure with these films.
In addition, a silane coupling agent or the like may be added in order to improve the adhesiveness to the substrate. Alternatively, an adhesive layer such as a silane coupling agent may be interposed. In addition, additives such as a heat resistance stabilizer, an antioxidant and a surfactant may be included.

The type of substrate used in the present invention is not limited, and a glass substrate on which a transparent electrode such as ITO is formed, a plastic substrate such as polyester, a glass substrate on which a thin film transistor array or a thin film diode array is formed, a silicone wafer Etc. can be used advantageously.

Next, the alignment film of the present invention is a liquid crystal device using a ferroelectric liquid crystal (SmC ^* ), a TFT (thin film transistor) type liquid crystal device, S
It is effective for any liquid crystal element such as BE (super twisted birefringence effect) type liquid crystal element, TN liquid crystal (twisted nematic liquid crystal) type liquid crystal element, and guest-host type liquid crystal element.

The liquid crystal device is used for pocket TVs, wall-mounted TVs,
Any type of computer terminal, word processor display, LCD shirt, display for vehicles such as automobiles can be used.

Next, a preferred embodiment of a liquid crystal cell using the alignment film of the present invention and using a ferroelectric liquid crystal is shown in the drawings.

1 is a partially cutaway perspective view, and FIG. 2 is a sectional view of FIG. In the figure, reference numerals 1 and 3 respectively denote a transparent electrode (not shown) having a predetermined pattern, and a glass substrate having an alignment film 7 formed on the surface thereof. (Hereinafter referred to as particles) 2 to uniformly disperse the gap length on the opposite direction side, and the sealing material 4 disposed on the peripheral portion of the substrate 1 and the epoxy resin adhesive particles containing the dispersed and mixed latent curing agent. The cells are heat-bonded by means of 8 and pulled to the opposite direction side to form a cell. The present invention has already been proposed in Japanese Patent Application No. 61-219273, so its details are omitted.

A liquid crystal material having a chiral smectic C phase is injected into such a cell structure and the injection port is sealed to form a liquid crystal element.

EXAMPLES Examples will be described below, but the present invention is not limited to the description of the examples.

Among the polymers used in the examples, polyfumaric acid esters are prepared by the method of Otsu et al. [Polymer Bulletin, 11 , 453 to 458 (1
984)], and poly-substituted acetylenes were prepared by the method of Masuda et al. [J. Am.
m.Soc., 105 , 7473-7474 (1983)].

The composition ratio of the liquid crystal composition is shown by weight%.

In the structural formulas below, * indicates an asymmetric carbon.

Further, in the example using the ferroelectric liquid crystal, a cell was prepared with the constitution shown in FIGS. As the epoxy adhesive particles 8, "Trepearl" AD manufactured by Toray Industries, Inc. was used.

Example 1 Diisopropyl polyfumarate (Mw = 250,000, was formed on the entire surface of a glass substrate on which a transparent electrode (ITO film) having a predetermined pattern was formed.
A 0.25 wt% chloroform solution having a viscosity index α = 0.98 was applied with a spinner. Then, it was naturally dried in the atmosphere to form an alignment film having a film thickness of about 300Å. This alignment film is 1 at 150 ℃
After the heat treatment for a period of time, a surface treatment by rubbing was performed. The two electrode substrates thus obtained were fixed with a spacer, and the periphery of the substrate was sealed with an epoxy adhesive to form a cell.

Then, a pyrimidine-based ferroelectric liquid crystal substance (described in JP-A-60-260564) was injected into the gap between the substrates. This liquid crystal composition is as follows.

When a driving voltage of 20 V was applied to this liquid crystal element, the liquid crystal molecules in the cell exhibited good bistability, and the excellent results were obtained with a contrast ratio of 15 and a response speed of 60 μsec. In addition, the orientation state by microscopic observation was also extremely excellent.

Furthermore, a mono-domain state close to an ideal state (a state in which white and black inversion occur in one pixel instantaneously) was obtained.

In the case of the conventional polyimide alignment film, the contrast ratio was 5 and the response speed was 120 μsec.

Example 2 0.25% by weight of dicyclohexyl fumarate (Mw = 450,000) on the entire surface of a glass substrate on which electrodes having a predetermined pattern were formed.
A chloroform solution was applied with a spinner and naturally dried to form an alignment film having a thickness of about 200 Å. After subjecting this alignment film to heat treatment and rubbing in the same manner as in Example 1, a liquid crystal element in which a pyrimidine-based ferroelectric liquid crystal substance was injected was assembled in the same manner as in Example 1. When a drive voltage of 20 V was applied to this liquid crystal element, the liquid crystal molecules exhibited good bistability as in Example 1, and exhibited excellent values in contrast ratio, response speed, and alignment state.

Example 3 Poly (1-trimethylsilyl-1-propyne) (Mw = 100) was formed on the entire surface of a glass substrate on which electrodes having a predetermined pattern were formed.
A 0.1 wt% chloroform solution having a viscosity index α = 1.04) was applied by a spinner and naturally dried to form an alignment film having a thickness of about 1000Å. This alignment film was used in Example 1.
After heat treatment and rubbing in the same manner as in (1), a liquid crystal element in which a pyrimidine-based ferroelectric liquid crystal substance was injected was assembled. When a drive voltage of 20 V was applied to this device, the liquid crystal molecules exhibited good bistability as in Example 1, and exhibited excellent values in contrast ratio, response speed, and alignment state.

Example 4 On the entire surface of a glass substrate on which electrodes having a predetermined pattern were formed,
Polyisopropyl fumarate, dicyclohexyl fumarate, and poly (1-trimethylsilyl-1-propyne) were respectively coated in the same manner as in Examples 1 to 3, heat-treated and rubbed, and then the ester-based ferroelectric liquid crystal substance was injected. Then, the liquid crystal element was assembled. An example of the composition of the ester-based ferroelectric liquid crystal substance is shown below. In each of the obtained devices, liquid crystal molecules showed good bistability as in Example 1, and excellent values were obtained in contrast ratio, response speed and alignment state.

Example 5 On the entire surface of a glass substrate on which electrodes having a predetermined pattern are formed,
Polyisopropyl fumarate, dicyclohexyl fumarate, and poly (1-trimethylsilyl-1-propyne), respectively, were applied in the same manner as in Example 4, followed by heat treatment and rubbing treatment, and then two sheets were twisted around 90 °. The rubbing direction of the substrates (A, B) was set, and a nematic liquid crystal substance was injected to assemble a liquid crystal device.

Each of the obtained devices showed a uniform alignment state, and good contrast was obtained.

Example 6 On the entire surface of a glass substrate on which electrodes having a predetermined pattern are formed,
Polyisopropyl fumarate, dicyclohexyl fumarate, and poly (1-trimethylsilyl-1-propyne) were respectively coated in the same manner as in Example 4, heat-treated, rubbed, and then twisted at 170 ° to 270 °. The rubbing direction of the two substrates (A, B) was set, and a nematic liquid crystal substance was injected to assemble a liquid crystal device. This element is called the SBE element.

Each of the obtained devices showed a uniform alignment state, and good contrast was obtained.

Example 7 On the entire surface of a glass substrate on which electrodes having a predetermined pattern were formed,
Polyisopropyl fumarate, dicyclohexyl fumarate, and poly (1-trimethylsilyl-1-propyne), respectively, were applied in the same manner as in Example 4, followed by heat treatment and rubbing treatment, and then the two substrates (A , B) were set parallel to each other, and a nematic liquid crystal substance containing several% by weight of a dye was injected to assemble a liquid crystal device. This element is called a GH type element.

Each of the obtained devices showed a uniform alignment state, and good contrast was obtained.

Example 8 Diisopropyl polyfumarate (Mw = 250,000) is formed on the entire surface of a glass substrate on which a transparent electrode (ITO film) having a predetermined pattern is formed.
0.25 wt% 1,1,3-trichlorotrifluoroethane solution of was applied with a spinner. Then, it was naturally dried in the atmosphere to form a liquid crystal alignment film. This alignment film was heat-treated at 150 ° C. for 1 hour and then surface-treated by rubbing. The two electrode substrates thus obtained are fixed with a spacer, and the periphery of the substrate is sealed with an epoxy adhesive,
A cell was formed.

Then, the phenylpyrimidine-based ferroelectric liquid crystal substance described in Example 1 was injected into the gap between the substrates.

When a driving voltage of 20 V was applied to this liquid crystal element, the liquid crystal molecules in the cell exhibited good bistability, and the display performance was excellent with a contrast ratio of 15 and a response speed of 60 μsec. In addition, the alignment state observed by a polarization microscope was also extremely excellent.

Example 9 A 0.5 wt% trichloroethylene solution of diisopropyl polyfumarate (Mw = 250,000) was applied by a spinner to the entire surface of a glass substrate on which electrodes having a predetermined pattern were formed. Then, it was naturally dried in the atmosphere to form a liquid crystal alignment film. After subjecting this alignment film to heat treatment and rubbing in the same manner as in Example 1, a liquid crystal element in which a phenylpyrimidine-based ferroelectric liquid crystal substance was injected was assembled in the same manner as in Example 1. When a drive voltage of 20 V was applied to this device, the liquid crystal molecules exhibited good bistability as in Example 1, and exhibited excellent performances in contrast ratio, response speed, and alignment state.

Example 10 0.5% by weight of diisopropyl polyfumarate (Mw = 250,000) 1 on the entire surface of a glass substrate on which electrodes having a predetermined pattern were formed.
The H, 1H, 5H-octafluoro-1-pentanol solution was applied with a spinner. Then, it was dried on a hot plate at 140 ° C. to form a liquid crystal alignment film. After subjecting this alignment film to heat treatment and rubbing in the same manner as in Example 1, a liquid crystal element in which a phenylpyrimidine-based ferroelectric liquid crystal substance was injected was assembled in the same manner as in Example 1. 20V to this element
When a driving voltage of (1) was applied, the liquid crystal molecules showed good bistability as in Example 1, and the contrast ratio, response speed,
Excellent performance was obtained in both orientation states.

Example 11 A 0.25 wt% chloroform solution of diisopropyl polyfumarate (Mw = 250,000) was applied on the entire surface of a glass substrate on which electrodes having a predetermined pattern were formed by a dip coating method at a pulling rate of 20 mm / min. Then, it was naturally dried in the atmosphere to form a liquid crystal alignment film. After subjecting this alignment film to heat treatment and rubbing in the same manner as in Example 1, a liquid crystal element in which a phenylpyrimidine-based ferroelectric liquid crystal substance was injected was assembled in the same manner as in Example 1. When a drive voltage of 20 V was applied to this device, the liquid crystal molecules exhibited good bistability as in Example 1, and exhibited excellent performances in contrast ratio, response speed, and alignment state.

Example 12 A 0.5% by weight ethyl trifluoroacetate solution of poly (isopropyl 1,1,2,2-tetrahydroperfluorodecyl fumarate) was applied on the entire surface of a glass substrate on which electrodes having a predetermined pattern were formed by a spinner. Then, it was naturally dried in the atmosphere to form a liquid crystal alignment film. After subjecting this alignment film to heat treatment and rubbing in the same manner as in Example 1, Example 1 was performed.
Similarly, a liquid crystal device in which a phenylpyrimidine-based ferroelectric liquid crystal substance was injected was assembled. When a drive voltage of 20 V was applied to this device, the liquid crystal molecules exhibited good bistability as in Example 1, and exhibited excellent performances in contrast ratio, response speed, and alignment state.

Example 13 Diisopropyl polyfumarate (MW = 250,000, on the entire surface of a glass substrate on which a transparent electrode (ITO film) having a predetermined pattern was formed
A 0.25 wt% chloroform solution having a viscosity index α = 0.98 was applied with a spinner. Then, let it air dry in the atmosphere,
An alignment film having a film thickness of 300Å was formed. This alignment film was heat-treated at 150 ° C. for 1 hour and then surface-treated by rubbing. The two electrode substrates thus obtained are fixed with a spacer, and the periphery of the substrate is sealed with an epoxy adhesive,
A cell was formed.

Next, the dielectric anisotropy is negative (Δε <
0) liquid crystal, for example BDH (Limited, Dorset, Englan
d) SCE5 to SCE6 manufactured by the above were injected. A direct current electric field was applied to this liquid crystal element to reverse it at a high speed due to the interaction between the permanent dipole and the electric field, and then a high frequency alternating voltage that could not follow the movement due to the interaction between the permanent dipole and the electric field was applied. However, due to the interaction between the dielectric anisotropy and the electric field, the liquid crystal molecules could be made direct current to the electric field, that is, parallel to the substrate. This state is almost equal to the ideal orientation state in which high contrast can be obtained. When you measure the contrast ratio,
When an alternating voltage with a voltage of about 13 V and a frequency of 15 KHz was applied after reversal, the contrast ratio was 30: 1.

On the other hand, when a liquid crystal with a negative dielectric anisotropy is driven in this way in a cell using a conventional alignment film such as polyimide, the alternating voltage applied after reversal is a high voltage of a voltage of about 60 V and a frequency of about 30 KHz. High frequency was needed.

This seems to be due to the following reasons. That is, since the force of making the liquid crystal molecules parallel to the substrate due to the dielectric anisotropy is proportional to ΔεE ^2, it means that the cell using the polyimide alignment film requires about 16 times the force of diisopropyl polyfumarate. In the cell using polyisopropyl difumarate, the initial alignment state is close to the ideal state, while in the cell using polyimide, it is considered that the cell is in the twist state. The closer this orientation is to the ideal orientation,
It is thought that the liquid crystal molecules can be made parallel to the substrate by an alternating voltage of low voltage and low frequency.

Among the ferroelectric liquid crystals having a negative dielectric anisotropy, the ferroelectric liquid crystal having a negative dielectric anisotropy with an increase in frequency has the same effect as that of the negative ferroelectric liquid crystal. .

Example 14 The surface tension of the polymer used in the examples was evaluated. The measurement was performed by casting a solution of various polymers on a glass plate, then using a dense film obtained by removing the solvent, and using a contact angle meter CA-D type manufactured by Kyowa Interface Science Co., Ltd. with various liquids. The contact angle was measured. Then, the surface energy of each polymer was calculated according to the method in the literature (Hata et al., Journal of Japan Adhesion Association, 8, No. 3, 131-141 (1972)). The results are shown in Table 1.

[Effects of the Invention] As described above, according to the present invention, by using a special polymer having a rod-shaped structure as an alignment film of liquid crystal, the contrast ratio is high and the image is good and the appearance is good. It is possible to obtain a mono-domain state close to that (a state in which white and black inversion occur in one pixel instantaneously at once), and it is possible to increase the response speed of the liquid crystal. In addition, it was possible to obtain an alignment film in which the alignment state of the liquid crystal substance was extremely excellent.

Furthermore, the present invention can provide a composition capable of forming a coating film uniformly and easily by various film forming methods by using a coating liquid composed of polyfumaric acid esters and a halogen-containing organic solvent, and liquid crystal alignment It was possible to obtain a thin film having a uniform thickness and excellent accuracy.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a preferred embodiment of a liquid crystal cell using a ferroelectric liquid crystal using the alignment film of the present invention, and FIG. 2 is a sectional view of FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kokichi Ito 6-31-1, Kameido, Koto-ku, Tokyo Seiko Electronics Co., Ltd. (72) Koji Iwasa 6-31-1, Kameido, Koto-ku, Tokyo Seiko Denshi Kogyo Co., Ltd. (72) Inventor Norio Kawabe 1-1-1, Sonoyama, Otsu City, Shiga Prefecture Toray Co., Ltd. Shiga Plant (72) Inventor Hiroyuki Ikeuchi 1-1-1, Sonoyama, Shiga Prefecture Toray Co., Ltd. Shiga Plant (56) Reference Japanese Patent Laid-Open No. 60-156043 (JP, A), Polymer Society of Japan, "Molecular Design of Polymers 1-Basics of Molecular Design-" (Sho 47-11-15) Baifukan P. 28

Claims (12)

[Claims] 1. In a liquid crystal device comprising at least a pair of electrode substrates, an alignment film and a liquid crystal, the alignment film has at least one organic solvent in the process of forming the alignment film when the viscosity index α of the formula represented by the following [I] is And 0 under temperature conditions.
A liquid crystal device comprising a polymer having a value of 85 or more and having a surface tension in the range of 8 to 35 dyn / cm. [Η] = K · M ^α [I] (In the formula [I], [η] is the intrinsic viscosity in the polymer solution viscosity measurement method, K is a constant, M is the molecular weight, and α is the viscosity index.) 2. A liquid crystal device according to claim 1, wherein the viscosity index α in the formula [I] is 0.95 or more. 3. A liquid crystal device according to claim 1, wherein the polymer is a polymer containing at least a polysubstituted acetylene, a polyfumaric acid ester or a copolymer thereof. 4. The liquid crystal device according to claim 3, wherein the poly-substituted acetylene is poly (trimethylsilylpropyne) or a derivative thereof. 5. A liquid crystal device comprising at least a pair of electrode substrates, an alignment film and a liquid crystal, wherein the alignment film is made of a polymer containing at least a polyfumarate ester or a copolymer thereof represented by the following general formula [II]. A liquid crystal element characterized in that (In the formula, R ¹ and R ² are the same or different groups, and are at least one selected from a linear or branched alkyl group, a cycloalkyl group, a halogenated alkyl group, a silalkyl group, and a siloxanylalkyl group. Represents an organic group of.) 6. The method according to claim 5, wherein the compound of the general formula [II]
R ¹ and R ² are the same or different groups, at least one of which is a secondary alkyl group having 3 to 9 carbon atoms, or 3 carbon atoms.
A liquid crystal device characterized by being selected from ~ 12 cycloalkyl groups. 7. The method according to claim 5, wherein the compound of the general formula [II]
A liquid crystal element, wherein R ¹ and R ² are the same or different groups and at least one is a fluorine-substituted alkyl group. 8. The method according to claim 5, wherein the compound of the general formula [II] is
A liquid crystal element, wherein R ¹ and R ² are one or more selected from an isopropyl group, a cyclohexyl group, or a derivative thereof. 9. The surface tension of polyfumaric acid ester or a copolymer thereof according to claim 5, wherein the surface tension is 8 to 40 dyn /
A liquid crystal element characterized by having a range of cm. 10. A coating composition for an alignment film of a liquid crystal device, which comprises a pair of electrode substrates, an alignment film and a liquid crystal,
A coating composition for a liquid crystal element alignment film, which comprises a polymer containing at least a polyfumarate ester or a copolymer thereof represented by the following general formula [II], and a halogen-containing organic solvent. (In the formula, R ¹ and R ² are the same or different groups, and are at least one selected from a linear or branched alkyl group, a cycloalkyl group, a halogenated alkyl group, a silalkyl group, and a siloxanylalkyl group. Represents an organic group of.) 11. The coating composition for a liquid crystal device alignment film according to claim 10, wherein the halogen-containing organic solvent is a fluorine-containing organic solvent. 12. The coating composition for liquid crystal device alignment film according to claim 10, wherein the concentration of the polyfumaric acid ester is in the range of 0.1% by weight to 30% by weight.