JPH03200118A - Liquid crystal cell - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a liquid crystal cell having a liquid crystal alignment film layer applied to a nematic type liquid crystal cell, a cholesteric type liquid crystal cell, a smectic type liquid crystal cell, etc. relates to a liquid crystal cell having an in-plane alignment polymerized thin film layer with excellent liquid crystal alignment ability.

[Prior art and its problems]

Displays are essential as an interface between information systems and humans, and liquid crystal display devices are attracting attention as one of them. This liquid crystal display device has features such as being thin and highly visible, can be driven with low power consumption, and is easy to drive with an IC.It has attracted attention from the market in its unique field, and research and development is actively progressing. It is being However, in order to put it into practical use as a liquid crystal display, the quality of the product is affected by color unevenness due to lack of uniformity when the screen is enlarged, and disturbances in the alignment of fine liquid crystals.

The structure of this liquid crystal cell consists of a substrate, an electrode formed on the substrate to drive the liquid crystal, an insulating film to prevent short circuit between the electrodes, and an alignment film to orient the liquid crystal. A well-known example is one in which two panels are combined and a liquid crystal is sealed in the space between them. In the structure of this cell, it is thought that most of the causes of the disturbance in the alignment of the liquid crystal as described above are due to the liquid crystal alignment film that aligns the liquid crystal by directly contacting the liquid crystal.

As this liquid crystal alignment film, there is an example in which an electrically insulating resin film such as polyimide is formed on a substrate or an electrode, and the surface is rubbed in one direction, and at least one of this alignment film is used. A type of liquid crystal cell assembled with this structure is known.

However, when this liquid crystal alignment film is formed by a wet method such as a spinner method or a printing method, the film surface becomes locally uneven due to dust being mixed into the film. Also,
If the film peels off during the rubbing process, or if there is dirt on the surface of the film or the rubbing material used to rub it, the surface may be scratched, or it may be difficult to uniformly rub a large area of the film. The problem is that it is difficult.

Therefore, when a liquid crystal cell is manufactured using such a liquid crystal alignment film, structural defects occur and a large area liquid crystal alignment film cannot be formed.

Therefore, several methods have been proposed to solve these problems in liquid crystal alignment films.

One method is to form a large-area film with a smooth surface.When raw monomers are evaporated in a vacuum processing chamber and polymerized on a substrate, the degree of vacuum in the processing chamber, the temperature of the substrate, and the There is a method for forming a synthetic resin film (Japanese Unexamined Patent Publication No. 63-206764) that forms a uniform synthetic resin film over the entire surface of a complex-shaped substrate by specifying the temperature of the inner surface of the wall. Applications to liquid crystal alignment films have been cited. However, this method of forming a synthetic resin film uses a vapor deposition method to form a synthetic resin film directly on the substrate in vacuum, so there is less possibility of dust etc. getting into the film, and compared to the wet method. Although it is expected that a smooth film will be formed, there is no disclosure about controlling the alignment of liquid crystals. Therefore, if conventional rubbing treatment is used to impart anisotropy to the film and orient the liquid crystal, the problems described above are unavoidable.

Another method is to evaporate polyimide monomer as a raw material in a vacuum to form a polyamic acid film on the electrode surface, expose the film surface to an electric discharge, and then heat it for imidization to produce polyimide. There is a method for forming a uniform liquid crystal aligning film over a large area and without scratching the film surface (Japanese Patent Application Laid-open No. 219029/1983). According to this method, the orientation is controlled by causing ions, electrons, etc. to be incident on the surface of the polyamic acid at an almost horizontal angle using an electric field. However, there is no specific disclosure of orientation, and the degree of orientation is unknown. In addition, in the active matrix drive method, which aims to improve display characteristics by incorporating field effect transistors into the elements of liquid crystal cells, thin film transistors (TFT: Th1) are used for driving.
However, when an alignment film is prepared using the ions, charge-up may destroy the TPT or disrupt its characteristics. In addition, even when TPT is not used, the film becomes electrored, and even when no voltage is externally applied to the liquid crystal cell, a voltage may be partially applied, that is, a cause of malfunction. In addition, it is known that under glow discharge, polymers are easily cut and decomposed, and active radicals and peroxy radicals are generated, which can cause the decomposition of liquid crystal molecules, as well as decomposition or oxidation. It is easily expected that low molecular weight ionic substances, such as carboxylic acids and amines, will be produced by this process, and the movement of these ionic substances by the electric field may disrupt cell characteristics, generate decomposition gases due to electrolysis, etc. There are problems such as deterioration due to reactions with polymers or liquid crystals. In addition, this method is time-consuming because it involves moving the substrate in a vacuum and involves many steps, and there is a problem in that it lacks mass productivity when producing liquid crystal cells using such a film.

As another example, nematic liquid crystals can be produced by forming several dozen metal oxides such as titanium (Ti), copper (Cu), etc. by oblique evaporation method on the surface of which a polyimide film has been deposited by vacuum evaporation polymerization method. (Yoshikazu Takahashi et al., Institute of Electronics, Information and Communication Engineers Technical Research Report: E
IM-85-49, EFM-85-28). However, with this technology, the orientation mechanism is not understood;
It has been pointed out that the orientation is not good, and since the film has to be operated twice in a vacuum system, it would be difficult to mass-produce it if it were to be used to make a liquid crystal cell. There is.

The above conventional methods have a major problem in that the manufacturing process is complicated, such as by performing two or more operations in a vacuum system when manufacturing a liquid crystal alignment film.

On the other hand, a method for producing a film for aligning ferroelectric liquid crystal obtained by accumulating polyimide film B on a substrate (applied physics,
Vol, 58. No, 7. P4O10,198
9). The LB method is a relatively simple film forming method, and since the nematic liquid crystal can be aligned in the direction in which the substrate is pulled up, the problems that occur during the rubbing process do not occur. However, this method is a wet film-forming method in which the substrate is directly immersed in a solvent, which prevents dust from getting into the film, makes it difficult to produce a film with a smooth surface over a large area, and also prevents the film from being insulating. In order to obtain a thick film with good quality, it is necessary to accumulate the film many times, and when used in a liquid crystal cell, there is a problem that the orientation of the liquid crystal is poor.

Therefore, the present inventors conducted intensive research to solve the problems of the prior art as described above, and as a result of conducting various systematic experiments, they came up with the present invention.

[Purpose of the invention]

An object of the present invention is to provide a liquid crystal cell having, as an alignment film for liquid crystal, an in-plane alignment polymeric thin film layer whose entire film is smooth and has excellent liquid crystal alignment ability.

The present inventors have focused on the following regarding the problems of the prior art described above.

In other words, as a liquid crystal alignment film, ■ contamination of the substrate is small;
The amount of contamination of impurities such as dust is extremely small; ■ The film is formed over a wide area with a uniform thickness and a smooth surface; ■ It has excellent liquid crystal alignment ability; ■ Liquid crystal cell We focused on the fact that when configured as a laminate, it has excellent adhesion with other layers and does not cause local structural defects in orientation.

In order to achieve this, (a) it is a structure in which a polymer film with in-plane orientation is directly formed on a substrate, especially an inorganic substrate, and (b) it is known for its high heat resistance and insulation resistance. We focused on the fact that when a liquid crystal alignment film is constructed by realizing an in-plane alignment film using condensation polymerization or polyaddition polymerization, a liquid crystal alignment film that enables the conditions (1) to (4) above can be produced.

More specifically, at least two types of monomers that cause condensation polymerization or polyaddition reactions are vapor-deposited on a base that has been given anisotropy, and each monomer can be adsorbed in a manner that reflects the information of the substrate, and the polymerization can be performed. If the object is a rigid molecule, it is possible to achieve in-plane orientation at least according to the information of the substrate at the initial stage of vapor deposition, and subsequently, even on a polymer with in-plane anisotropy, a polymer with similar anisotropy can be formed. was thought to be generated. If this is possible, it will be possible to provide a liquid crystal alignment film having an in-plane alignment polymerized thin film layer with excellent in-plane alignment.

[Description of the first invention] Structure of the first invention The liquid crystal cell of the first invention comprises a pair of substrates, at least one of which is a transparent substrate, and a transparent electrode formed on the inner surface of the transparent substrate. a pair of insulating films formed on the inner surface of the electrode, including a pair of electrodes formed on the inner surface of the electrode, a transparent insulating film formed on the inner surface of the transparent electrode, and at least one of the pair of insulating films. 9 formed on one inner surface
A liquid crystal alignment film consisting of a base having in-plane anisotropy on the surface and a polyaddition polymer film or condensation polymer film excluding a ring-opening polymer formed directly on the in-plane anisotropy portion of the base, It is characterized by comprising a liquid crystal layer sealed in a space formed between a liquid crystal alignment film and the insulating film or between the liquid crystal alignment films.

Functions and Effects of the First Invention The liquid crystal cell of the first invention uses a liquid crystal alignment film having an in-plane alignment polymerized thin film with excellent liquid crystal alignment ability. Because it is possible to easily create a smooth film over a large area, there is less chance of color unevenness in the liquid crystal cell and less possibility of dust getting into the film.
Local structural defects are less likely to occur.

In addition, the liquid crystal cell of the present invention can produce a homogeneous film over a wide area due to the characteristics of the manufacturing method of the liquid crystal alignment film used, so that it is possible to create a large area liquid crystal cell with the excellent properties described above. You can also expect

The mechanism by which the liquid crystal cell of the first invention exhibits the above-mentioned effects is not necessarily clear yet, but it is thought to be as follows.

That is, the liquid crystal cell of the first invention is constructed using a liquid crystal alignment film consisting of a base and an in-plane alignment polymeric thin film formed directly on the surface of the base. The in-plane alignment polymerized thin film of the liquid crystal alignment film used in this liquid crystal cell maintains in-plane anisotropy due to the interaction between the orientation of the functional groups of the rubbing material adhered to the substrate and the functional groups of the vapor-deposited material. It is a film with a three-dimensional orientation structure that maintains its orientation all the way to the surface.

This liquid crystal alignment film is formed by directly forming an in-plane alignment polymeric thin film on the base surface in vacuum, which means that there is less contamination of the substrate than with the wet method, and impurities such as dust get into the film. The amount of contamination is extremely small. In addition, it has excellent liquid crystal alignment ability. Furthermore, even if the film has a wide area, the film thickness is uniform and the film surface is smooth. Furthermore, when configured as a liquid crystal cell, it has excellent adhesion with other layers and does not cause local structural defects in orientation.

Furthermore, the liquid crystal alignment film is composed of an in-plane alignment polymer thin film made of condensation polymerization or polyaddition polymerization, and therefore has excellent heat resistance and insulation resistance.

In the present invention, by using an excellent liquid crystal alignment film having such features, there is less possibility of uneven liquid crystal alignment and fine structural defects that occur in conventional liquid crystal cells (
Therefore, it seems that a liquid crystal cell with excellent liquid crystal alignment ability was obtained.

Incidentally, it is thought that the alignment of the liquid crystal is due to some kind of interfacial interaction between the liquid crystal and this liquid crystal alignment film. This kind of thinking has been around for a long time.For example, there are examples in which a pre-formed film-like polymer film is stretched in one direction and then used as an alignment film for liquid crystals.
In the case of LB films, the liquid crystal is oriented along the pulling direction from the solution during film formation, so rubbing the surface of the alignment film and creating grooves does not necessarily have the ability to align the liquid crystal. I can say that. Additionally, this means that even if unevenness occurs on the substrate surface due to rubbing of the polymerized film produced by the vapor deposition polymerization method of the present invention, even if a film is formed thick enough to cover and hide the unevenness, the liquid crystal alignment ability is maintained. This can be inferred from the fact that it has

Therefore, the liquid crystal cell using the liquid crystal alignment film having the characteristic in-plane alignment polymerized thin film of the present invention can prevent the problems that occur during the rubbing treatment, and furthermore, the liquid crystal alignment film can be formed uniformly and over a large area. It is thought that a liquid crystal cell with a large area, less unevenness, and less likely to have minute structural defects could be produced because it is easy to fabricate and there is little possibility of dust getting into the film.

[Description of the second invention] The second invention is an invention having the same object as the first invention.

Structure of the Second Invention The liquid crystal cell of the second invention includes a pair of substrates, at least one of which is a transparent substrate, and a transparent electrode formed on the inner surface of the transparent substrate. a pair of electrodes, the pair of electrodes having a base portion with in-plane anisotropy on the inner surface of at least one of the electrodes; An in-plane oriented polymeric thin film formed directly on the surface of an anisotropic base and made of a polyaddition polymer film or a condensation polymer film excluding a ring-opening polymer and has electrical insulation properties, and between the in-plane oriented polymeric thin film, or a liquid crystal layer sealed in a space formed between the in-plane oriented polymeric thin film and an insulating film further formed on the inner surface of the electrode;
It is characterized by consisting of.

Functions and Effects of the Second Invention The second invention not only provides the same functions and effects as the first invention, but also has the following effects.

That is, in the second invention, the base of the liquid crystal alignment film of the first invention is formed by imparting in-plane anisotropy to the surface of the electrode, and the in-plane alignment polymerized thin film of the liquid crystal alignment film is electrically Since it has insulating properties, an insulating film can be omitted, and a liquid crystal cell can be constructed with a simple structure. Therefore, since it is not necessary to have a complicated layered structure, local structural defects are less likely to occur.

[Description of other inventions of the first invention and the second invention] Other inventions of the first invention and the second invention will be described below.

In the liquid crystal cells of the first and second aspects of the present invention, at least one of the substrates is transparent because it is necessary for the substrates to optically sense information such as an electric field applied to the liquid crystal. Here, transparent means that light in the wavelength range necessary to obtain optical information is transmitted. Therefore, this light transmittance may be for the entire visible light range, or it may be for only a certain wavelength as in a color filter. Further, the transmittance does not need to be 100%, and it is sufficient that the transmittance is sufficient to sense optical information. Specifically, inorganic substrates include glass, quartz glass, and various crystals, and organic substrates include polymer materials and
For example, organic glasses such as polymethyl methacrylate and polyethyl acrylate, polycarbonate, polystyrene,
Examples include transparent polymer materials such as polyimide. Further, as the other pair of substrates, the same transparent substrate as described above may be used, or an opaque material such as metal or silicon wafer may be used depending on the purpose. Note that a stack of these materials may also be used.

The condition of the substrate surface must be such that there will be no thickness unevenness when forming a liquid crystal cell, and there will be no defects when forming insulating films, liquid crystal alignment films, etc. Preferably, the smoothness is such that no structural defects are observed in the region. The degree of smoothness cannot be determined because it varies depending on the thickness of the liquid crystal cell, but
It is preferable that there are no grooves or irregularities of 1 μm or more. Incidentally, it is also possible to smooth the surface condition by laminating electrodes, an insulating film, an alignment film, etc. on the top of the substrate.

In addition, the thickness of the substrate is not particularly limited, but
From the viewpoint of ensuring mechanical strength, the thickness is preferably 1 μm or more, more preferably 100 μm. Also,
The shape of the substrate is usually planar, but may be curved as long as the distance between the substrates can be kept approximately constant when the cell is assembled.

Furthermore, the electrodes are used to provide electric field information to the liquid crystal molecules via the insulating film, and since it is not necessary to flow a large amount of current, the electrodes do not necessarily need to have a low resistance value. The electrode preferably has a sheet resistance of 0 to IMΩ/hole, preferably 0 to 100Ω/hole. In addition, if the electrode is formed on a transparent substrate and transparency is required,
A material having a certain degree of transparency in the target wavelength range is selected, and specifically, a transparent electrode such as indium tin oxide or tin oxide can be suitably used. However, even metals can be used depending on the purpose because light transmittance occurs when the film thickness is thin. Depending on the application, the other electrode in the pair may be a transparent electrode similar to the above, or a metal with high light reflectance such as aluminum, gold, or platinum if a reflective type liquid crystal cell is used. can be used.

Furthermore, a semiconductor such as silicon can be used. These electrodes generally have a structure in which they are laminated directly on the substrate, but if the substrate is a conductor such as metal, there is no need to intentionally form the electrodes, and it is possible to form the substrate and electrodes integrally. can.

Note that the thickness of the electrode varies depending on the light transmittance, the desired resistance value, and the manufacturing method, so it cannot be said that it is eccentrically placed.
The thickness is preferably 10 Å or more, preferably 100 Å or more, and is appropriately determined depending on the application. It is preferable that the surface condition of the electrode is smooth like the surface condition of the substrate.

The shape of the electrode depends on the shape of the substrate, but it may be formed on the entire surface of the substrate, or it may be formed only on desired parts by a technique such as patterning. For example, a dot matrix may be constructed, such as a liquid crystal cell in which two linear electrodes are stacked at right angles. Further, methods for producing the electrode include ordinary vapor phase film forming methods such as sputtering and vacuum evaporation, and wet film forming methods such as dipping. Further, it is desirable that the adhesion between the electrode and the substrate be so good that it will not peel off during use or during the production of a liquid crystal cell.

Further, the insulating film is an intermediate layer for preventing deterioration caused by electrochemical reactions caused by direct contact between liquid crystal molecules and electrodes, and problems caused by dielectric breakdown. In addition, when the liquid crystal alignment film itself has high insulating properties, the insulating film and the liquid crystal alignment film can be integrally constituted. At this time, the liquid crystal alignment film needs to function sufficiently as an insulating film by itself. Furthermore, the term "insulation" here refers to high electrical resistance and no dielectric breakdown when voltage is applied, that is, high voltage resistance. The insulating properties of the insulating film, that is, the electrical resistance and voltage resistance, vary depending on the type and thickness of the insulating film, and are determined by the applied voltage, cell thickness, electrochemical reactivity of the liquid crystal, etc. Although it is not possible to specify, for the former electrical resistance, an insulating film of 100 Ω or more, preferably 1 Ω or more is preferably used, and for voltage resistance, an insulating film of 1 kV/cm or more, preferably 10 kV/cm or more is suitably used. . The thickness of the insulating film may be such that it has high electrical resistance under the operating voltage and does not cause dielectric breakdown. Note that the film thickness is 1 from the viewpoint of pressure resistance.
The thickness is required to be 0 Å or more, preferably 100 Å or more. Further, since a voltage drop occurs when the film thickness becomes thicker, it is preferably 1 mm or less. In addition, when the insulating film is on the transparent layer side, a film that is transparent in the target wavelength range is used, and specifically, Si02.813N<, Tl
Inorganic insulating films such as 02, Ta206, Al2O3,
Examples include organic insulating films such as polyimide. Among these, an inorganic insulating film that is less prone to scratches is preferred. The surface of the insulating film is preferably smooth like the substrate and electrodes. The shape of the insulating film depends on the shapes of the substrate and electrodes, but it may be formed on the entire surface of the substrate or electrode, or it may be formed only on desired areas where insulation is required by a technique such as patterning. Further, the adhesion is sufficient as long as it does not peel off during use and cell assembly.

Methods for producing the insulating film include ordinary vapor phase film forming methods such as sputtering and vacuum evaporation, and wet film forming methods such as dipping.

Further, the liquid crystal alignment film is formed directly on a base having in-plane anisotropy at least on the surface and an in-plane anisotropy portion of the base,
Information on the in-plane anisotropy formed in the in-plane anisotropic portion of the substrate is
It is formed by propagating the orientation of the polymeric main chain or functional group to the membrane surface with in-plane anisotropy. Except for ring-opening polymers (consisting of polyaddition polymer films or condensation polymer films).

The base of the liquid crystal alignment film holds/transmits in-plane orientation information imparted with in-plane anisotropy, which is information for controlling and determining the in-plane orientation of a functional member having an oriented polymeric thin film. It is not particularly limited as long as it is a material that satisfies this. Alternatively, the electrode or insulating film may be made of a material that satisfies this requirement, and the base may also serve as the electrode or insulating film, thereby omitting a part of the structure. Specific examples of the materials include various crystals, insulators such as glass and quartz, semiconductors such as silicon, transparent electrodes such as indium tin oxide, and inorganic materials made of inorganic substances such as metals such as aluminum and gold. It will be done. Among these, those that do not cause scratches when imparting in-plane anisotropy are preferred. A polymeric material can be used similarly as an organic material made of an organic substance, but in this case, it is necessary to use a material that is difficult to scratch when imparting in-plane anisotropy, and the critical surface tension of the polymeric material to impart anisotropy. It is necessary that the critical surface tension of the material is significantly different from the critical surface tension of the material.

Regarding the surface condition of the base, in-plane anisotropy must be imparted, and special materials such as single crystals can be used, but
Preferably, a substrate such as an electrode or an insulating film is rubbed in one direction with a polymer material to partially adhere the polymer. Further, it is possible to use a substrate in which fine grooves or a composition distribution are formed in one direction on the substrate surface by oblique vapor deposition or the like.

The material of the rubbing material used in this rubbing process requires that the rubbing material slightly adhere to the surface of the substrate.
Organic materials are preferred. In particular, if it volatilizes or melts under the film forming conditions, anisotropy will not be imparted substantially.
More preferably, it is a polymeric material. Among polymer materials, it varies depending on the combination with the substrate and the affinity with the monomer. Hydrophobic polymeric materials with large differences in performance can be used. In particular, a hydrophilic polymer material with a critical surface tension of 35 dyn/cm or more or a hydrophobic polymer material with a critical surface tension of 20 dyn/cm or less is suitable. Specifically, hydrophilic polymer materials include polyacrylonitrile, cotton, polyacrylic acid, hydroxymethyl methacrylic acid, polyvinyl alcohol, polyamide, polyacrylamide, etc., and hydrophobic polymer materials include polytetrafluoroethylene. .

Further, even in the middle, although the orientation is inferior to the hydrophilic polymer material and the hydrophobic polymer material, it may show some degree of orientation, and it can be selected as appropriate depending on the required characteristics.

Further, the rubbing treatment does not need to be performed on the entire surface of the substrate, and may be performed only on the portion where the alignment film is desired to be formed. Moreover, the shape of the rubbing material may be any shape, such as fibrous, film, or block.

It is thought that by rubbing with a polymeric material, the polymeric material is partially attached to the surface of the substrate in a linear manner.

Based on this information, an oriented polymer film is formed on the entire surface of the substrate, so the entire surface of the substrate is not covered with a polymer rubbing material. Therefore, the polymer film is formed in close contact with the substrate. Further, the number of times of rubbing is not limited, and it is usually sufficient to perform the rubbing several times to several tens of times. Furthermore, the direction of rubbing must always be parallel, and any deviation will naturally disrupt the orientation of the polymer film. In addition to rubbing the entire substrate in the same direction, we can also change the rubbing direction of only a part of the substrate, change the orientation of the polymer film, or rub it in a curved shape.
It is also possible to obtain an alignment film that conforms to this.

Further, the in-plane oriented polymer thin film is a polyaddition polymer or condensation polymer film excluding ring-opening polymerization. Examples of the former polyaddition polymer include polyurea and polyurethane, and examples of the latter condensation polymer include polyamide, polyazomethine, and polyester. Each polymer is produced by reacting a difunctional isocyanate, an acid chloride, an aldehyde with a diamine, or a difunctional alcohol. The most preferred among them is polyamide. This is considered to be due to the hydrogen bonding between the polymer and the monomer.

In-plane orientation refers to the information given to the base when the liquid crystal alignment film is viewed from above, for example, the state in which main chains or functional groups such as carbonyl groups are arranged in a direction parallel to or perpendicular to the rubbing direction. As expected. Therefore, the main chain and the functional groups do not all have to be parallel to the base, but may be tilted in a certain direction while maintaining a certain angle with the substrate.

Also, there is no need for all molecules to be oriented in a certain direction (,
It also refers to a state in which the individual molecules are oriented in an anisotropic direction as a whole, even if they are somewhat random. Therefore, the in-plane orientation here refers to base information using infrared spectroscopy, for example, observing the difference spectrum between transmission spectra measured by irradiating and transmitting polarized light in directions parallel and orthogonal to the rubbing direction perpendicularly to the base, and If dichroism in the absorption of the functional group is detected, and by placing the film between polarizers of crossed nicols, the base information, e.g. If birefringence is confirmed by rotating, and two films of guest-host type liquid crystal are injected into cells fixed at regular intervals so that the base information, for example, the rubbing directions are located parallel to each other, the liquid crystal This refers to a case where the orientation of the film can be indirectly confirmed by checking the orientation. The liquid crystal alignment film only needs to have alignment properties up to the surface,
The film thickness is not particularly limited, but is 10 Å or more.
00 μm or less, preferably 100 Å or more and 10 μm
The following are more preferred.

In the production of this in-plane oriented polymeric thin film, first, a base portion imparted with in-plane anisotropy is placed in a vacuum evaporation apparatus, and two types of reactions are performed on the base surface: polyaddition reactions other than ring-opening polymerization or condensation polymerization reactions. This is carried out by simultaneously vapor-depositing the above monomers and transmitting information on the in-plane anisotropy formed in the base surface layer to the surface of the vapor-deposited film, thereby forming an in-plane oriented polymeric thin film.

The monomers used here are two or more types of monomers that cause polyaddition or polycondensation reactions other than ring-opening polymerization. Specifically, difunctional acid chlorides such as terephthalic acid chloride and sebacic acid chloride, diisocyanate compounds such as phenyl diisocyanate and methylene diisocyanate, dialdehyde compounds such as terephthalaldehyde, and decamethylene diamine, hexamenediamine, etc. fatty acid diamine, paraphenylenediamine, 4゜4
゛-One type of aromatic diamine such as diaminodiphenyl ether is used. In addition, when producing polyurethane, diisocyanate and rose hydroxyphenol,
Examples include ethylene glycol-based difunctional alcohols, and in the case of producing polyester, difunctional acid chlorides and difunctional alcohols.

Note that the directionality of monomer adsorption must be determined according to the in-plane anisotropy imparted to the base at the initial stage of polymerization, and according to the anisotropy of the polymerized film thereafter.

Therefore, when the polymerization rate is high, molecules adsorbed in random directions may be involved in the polymerization.

In this case, the monomer supply determines the polymerization rate. In order to develop in-plane anisotropy, it is necessary to conduct polymerization in a state where monomer adsorption and desorption are occurring vigorously, rather than being rate-limited by monomer supply. This is because monomers that are adsorbed in a more stable state have a longer adsorption lifetime (adsorption time) and are more likely to participate in the polymerization reaction, whereas monomers that are adsorbed in an unstable direction have a longer lifetime. This is because it is short and cannot participate in the polymerization reaction. Therefore, the molecules adsorbed in a stable state, that is, in this case, in a state according to the anisotropy of the base and the anisotropy of the polymeric film, participate in the reaction and achieve in-plane orientation. Methods for reducing the amount of monomer adsorption include increasing the base temperature or decreasing the partial pressure.

In addition, in this polymerized thin film forming step, in order to obtain an in-plane oriented film, the base temperature may be raised and the polymerization rate may be made slower than the rate-determining rate of monomer supply. However, if the temperature is too high, the polymerization rate will drop significantly, which is not practical. Since the temperature range cannot be specified depending on polymerization and adsorption properties, we measured the relationship between the polymerization rate and the base temperature for each monomer series, and determined that even if the substrate temperature was lowered, the polymerization rate would not change much compared to when it was higher than that. It is necessary to determine the temperature at which the monomer supply rate is eliminated (the temperature that determines the monomer supply rate), and it is preferable to set the base temperature higher than the temperature that determines the monomer supply rate.

On the other hand, under certain monomer supply conditions, even at the temperature that determines the monomer supply rate, when the monomer supply amount is reduced, that is, when the monomer partial pressure of the system is lowered, the amount of monomer adsorption decreases.
Since adsorption and desorption occur vigorously, this temperature can be suitable.

In this case as well, conditions cannot be specified depending on polymerization and adsorption properties. Therefore, similarly to the above, the temperature range that determines the rate of monomer supply must be determined for each supply condition, and the temperature must be determined. However, as a trend, it can be said that when it is desired to lower the base temperature and produce an alignment film, it is necessary to lower the monomer supply, that is, the monomer partial pressure. In addition, if one of the monomers has poor volatility, it is necessary to determine the above base temperature and monomer supply amount with an excess of the highly volatile monomer and a reduced amount of the less volatile monomer. If the volatility of both monomers is poor, the adsorption properties will increase, so naturally it is necessary to raise the base temperature or reduce the monomer supply amount to satisfy the above conditions.

The polymer film produced as described above is a polymer film in which base information is transmitted to the film surface. In addition, it is also possible to use two or more types of monomers to produce an alignment film in which each of these monomers is contained in a polymer molecule. Furthermore, unlike a liquid crystal alignment film produced using ion implantation, there is no influence of ion implantation, charge-up, etc., and the problems of the ion implantation method described above can be solved.

Although the mechanism by which this liquid crystal alignment film exhibits excellent in-plane alignment effects is still not clear,
It can be considered as follows.

In other words, in the conventional vapor deposition polymerization method, polymerization is thought to proceed due to the adsorbed monomers, but since the direction of adsorption is isodirectional within the substrate plane, a polymer film with in-plane anisotropy is not formed. . On the other hand, the liquid crystal alignment film of the present invention has a structure in which a polymeric thin film is directly formed on a base provided with in-plane anisotropy so that the in-plane directionality of adsorbed molecules can be controlled. The direction of the monomer directly adsorbed on the base, that is, the directionality of the functional group involved in polymerization, is determined by the in-plane anisotropy imparted to the base,
This achieves in-plane anisotropy of the polymeric thin film directly in contact with the base. Furthermore, since the polymer film directly formed on the base has anisotropy, the polymer film accumulated on the surface of the polymer film formed directly on the base has an adsorbed and polymerized structure that reflects that information. Therefore, the polymer film is formed with orientation up to the film surface.

Moreover, in the liquid crystal alignment film of the present invention, the in-plane alignment polymerized thin film is composed of a polyaddition polymer film or a condensation polymer film excluding the ring-opening polymer, and the condensation polymer or polyaddition polymer has a carbonyl group, an amino group, Since the monomer and polymer have polar groups such as amide groups, they have hydrogen bonding ability and are rigid polymers, resulting in a polymer film with excellent in-plane anisotropy.

The liquid crystal alignment film having the in-plane alignment polymeric thin film of the present invention is also very useful as a polymer material. In the conventional method, liquid crystal spinning,
It was developed as a high-strength fiber by ensuring orientation through complicated techniques such as stretching. However, these materials often have very high melting points or are insoluble in solvents, making it difficult to make them into thin films. On the other hand, although vapor deposition polymerization can easily form a thin film, it cannot impart in-plane orientation. Therefore, conventional in-plane orientation is limited to special examples such as conductive materials, and the present invention uses polymer films with excellent heat resistance and insulation properties such as the above-mentioned polycondensation and polyaddition polymers. There are no known examples of orientation control. From the above, the liquid crystal alignment film used in the present invention is an in-plane alignment film having a novel higher-order structure, chemical structure, and physical properties.

Further, the liquid crystal layer uses a type of liquid crystal that requires an alignment film during use, such as a nematic liquid crystal, a cholesteric liquid crystal, or a smectic liquid crystal.

Next, a specific example of the method for manufacturing a liquid crystal cell of the present invention will be briefly described below.

First, a silicon wafer, glass, or the like is prepared as a substrate material, and a transparent electrode material such as indium tin oxide is coated on the surface of the substrate. Then,
A polymer material is applied in one direction to the electrode surface formed on the substrate.
For example, by rubbing with cotton, polyacrylonitrile, polyacrylic acid, hydroxyethyl polymethacrylate, or Teflon fiber or sheet, in-plane anisotropy is imparted to the electrode surface of the substrate, and the base portion imparted with in-plane anisotropy is Obtain a substrate having the following properties. Next, this substrate is placed in a vacuum chamber and maintained at a predetermined temperature as required. At the position facing the substrate, condensation polymerization,
Two types of monomers that cause a polyaddition reaction, such as terephthalic acid chloride, sebacic acid dichloride, methylene diphenyl isocyanate, terephthalaldehyde, etc., fatty acid diamine such as decamethylene diamine, hexamenediamine, and paraphenylene diamine, 4,4"
One type of aromatic cyamine such as diaminodiphenyl ether, and a difunctional alcohol such as ethylene glycol and para-hydroxyphenol are placed in separate containers. The temperature of each container can be adjusted by a heater, and the opening of the container, that is, the spout of monomer vapor, has a mechanism in which the degree of opening and closing can be adjusted by a shutter as necessary.

The inside of the vacuum chamber is heated to 10” Torr using an oil diffusion pump, etc.
After exhausting the air, each monomer container is heated to a predetermined temperature, and the shutters are opened to blow out both monomers. At this time,
Finely adjust the degree of opening and closing of the shutter so that the amount of ejection of both monomers does not differ significantly. The pressure during vapor deposition is I x 10
-5 to IX 10-3 Torr. If you want to strictly control the spouting amount of each monomer, you can do so by installing a film thickness monitor using a crystal oscillator near each monomer spout, and for monomers with relatively high volatility, With the spout of the monomer container containing the smaller amount, that is, the one with the lower vapor pressure at the monomer temperature, fully open, finely adjust the opening/closing degree of the shutter of the other monomer container spout, so that the pressure measured with the ion gauge is It may be set to the lowest value. This is because as the polymerization reaction progresses, the system pressure decreases due to the decrease in volatility, and the relative sensitivity of the low molecular weight gas produced by the condensation reaction to the monomer on the ion gauge is low, so the pressure measured with the ion gauge The lowest pressure indicates that both monomers are present in approximately a 1:1 ratio since . In addition, if one monomer is extremely volatile, the less volatile monomer is fully opened in the same manner as above, and the pressure is slightly higher than the minimum, and the highly volatile monomer is supplied in excess. You can keep it in the same condition as it is.

This state can be confirmed by the fact that the pressure increases when the supply of the monomer with low volatility is stopped, and the pressure decreases when the monomer is supplied. By performing open film formation at a predetermined time in this way, it is possible to obtain a substrate having a liquid crystal alignment film in which an in-plane alignment polymerized thin film is directly formed on the base. The formation time of the in-plane oriented polymeric thin film varies depending on the polymerization rate, substrate temperature, system pressure, and desired film thickness. Evaluation of in-plane orientation is confirmed by infrared spectroscopy, measurement of birefringence, and liquid crystal alignment ability as described above. In particular, whether it has in-plane orientation up to the surface,
This can be confirmed by liquid crystal alignment ability.

Next, a cell is assembled using two of the substrates having liquid crystal alignment films. At this time, they are aligned so that the anisotropic directions of the liquid crystal alignment films are parallel, or at a predetermined angle from parallel to such an extent that the alignment is not disturbed when the liquid crystal is sealed. In addition, when using a single substrate with a liquid crystal alignment film formed on it,
On the other hand, use a material with a smooth surface that does not disturb the orientation of the liquid crystal. Furthermore, the cell gap is determined according to the orientation state of each liquid crystal and the purpose of use, and the two substrates are bonded, leaving an inlet for the liquid crystal, to assemble the cell.

Next, liquid crystal is sealed in this cell. In addition, in order to prevent stress from encapsulating the liquid crystal from remaining inside the liquid crystal cell, the cell is heated to above the clear point temperature of the liquid crystal to be encapsulated, and when the desired temperature is reached, the liquid crystal is encapsulated, and the orientation during rapid cooling is adjusted. A liquid crystal cell is obtained by slowly cooling to room temperature to prevent disturbance of the liquid crystal.

Specific examples of the structure of the liquid crystal cell thus obtained are shown in FIGS. 1 to 6.

First, let's talk about the specific structure of the one-sided transparent liquid crystal cell.
A description will be given along with a specific example of the liquid crystal cell structure shown in the figures through FIG.

Specific structural example 1 of the one-side transparent liquid crystal cell of the present invention is the first
As shown in the figure, a first base portion consisting of a transparent substrate At, a transparent electrode B1, a transparent insulating film CI, and an alignment film D1, a substrate a1, an electrode b1, an insulating film cl, and an alignment film Dl°
and a liquid crystal EI sealed between the first layer and the second layer. In this case, the transparent insulating film CI and the alignment film D+, and the insulating film cl and the alignment film DI'
may be formed by providing the alignment films D1 and D]' with the function of an insulating film, respectively, and omitting the insulating film. In addition, in order to make a one-sided transparent liquid crystal cell, the second layer may also be configured such that at least one of the layers disposed outside the liquid crystal alignment film DL° is a layer having light reflection performance. Even if a reflective plate is provided between the layers outside the liquid crystal alignment film DI',
Furthermore, a reflecting plate may be provided outside the substrate a1.

Next, as shown in FIG. 2, a specific structure example 2 includes a first layer portion consisting of a transparent substrate A2, a transparent electrode B2, a transparent insulating film C2, and an alignment film D2, a substrate a2, an electrode b2, and an insulating film c2, and a liquid crystal E2 sealed between the first layer and the second layer. In this case, the transparent insulating film C2 and the alignment film D2 may be formed by giving D2 the function of an insulating film and omitting the insulating film. In addition,
This specific example is an example in which the alignment film is provided in the transparent first layer portion. Further, the light reflection performance can be imparted to the second layer on the second layer side from the liquid crystal layer in the same manner as in the above-mentioned specific structure 1.

Next, as shown in FIG. 3, specific structure example 3 includes a first layer portion consisting of a transparent substrate A3, a transparent electrode B3, and a transparent insulating film C3; and an alignment film D3, and a liquid crystal E3 sealed between the first layer and the second layer. In this case, the transparent insulating film c3 and the alignment film D3 may be formed by giving D3 the function of an insulating film and omitting the insulating film. In addition,
This specific example is an example in which the alignment film is provided in the non-transparent second layer portion. Moreover, the provision of light reflection performance to the second layer can be configured in the same manner as in the above-mentioned specific structure 1.

Next, we will discuss the specific structure of the fully transparent liquid crystal cell in the fourth section.
This will be explained along with a specific example of the liquid crystal cell structure shown in the figure and FIG.

Specific structural example 1 of the fully transparent liquid crystal cell of the present invention is the fourth
As shown in the figure, a first layer portion consisting of a transparent substrate A4, a transparent electrode B4, a transparent insulating film C4, and an alignment film D4, a transparent substrate A4', a transparent electrode B4, a transparent insulating film C4', and an alignment film. D4', and liquid crystal E4 sealed between the first layer and the second layer. In this case, the transparent insulating film C4 and the alignment film D4, and the transparent insulating film 04° and the alignment film D4' are D4 and D4', respectively.
The insulating film may be omitted so that the insulating film functions as an insulating film.

Next, as shown in FIG. 5, a specific structure example 5 includes a first layer portion consisting of a transparent substrate A5, a transparent electrode B5, a transparent insulating film C5, and an alignment film D5, and a substrate A5' and an electrode B5. °,
and an insulating film C5', and a liquid crystal E5 sealed between the first layer and the second layer. In this case, the transparent insulating film C5 and the alignment film D5 may be formed by giving D5 the function of an insulating film and omitting the insulating film.

Note that this specific example is an example in which the alignment film is provided in the transparent first layer portion.

Next, as shown in FIG. 6, the specific structure example 6 has a first layer portion consisting of a transparent substrate, a transparent electrode, a transparent insulating film, and a liquid crystal alignment film, and/or a second layer portion, as shown in FIG. Department,
This is an example constituted by a transparent substrate A6, a transparent electrode B6 which also serves as a base portion D61 of the liquid crystal alignment film (1) 6, and an in-plane alignment polymeric thin film 62 which also serves as an insulating film. That is, in this example, in-plane anisotropy is imparted to the inner surface of the transparent electrode B6, and an in-plane anisotropy that also serves as an insulating film is provided on the surface of the in-plane anisotropy imparting portion (D61) of the transparent electrode B6. This is an example in which a liquid crystal alignment film is covered with an alignment polymerized thin film D62, and a base portion D61 having an in-plane anisotropy imparting portion of the transparent electrode B6 and an in-plane alignment polymerized thin film D62.

Note that the liquid crystal cell of the present invention is not limited to the specific structural examples 1 to 6 described above, and may have any structure as long as the features of the liquid crystal alignment film of the present invention are utilized.

In addition, the liquid crystal alignment film shown in the concrete structural example 6 can also be applied to the said concrete structural examples 1-5.

[Description of the Third Invention] The third invention relates to the use of the liquid crystal cell of the first invention, which has a faster switching speed than a nematic liquid crystal and retains the state in memory even after the applied voltage is turned off. This application invention is applied to a ferroelectric liquid crystal that has the following characteristics.

Fudeyu Shin Plate Ω Dansen In addition to the above objects, the invention has the following objects.

Another object of the third invention is to use a ferroelectric liquid crystal (FLC) having excellent memory properties.
c Liquid Crystal) cells.

The ferroelectric liquid crystal cell of the third invention includes a pair of substrates, at least one of which is a transparent substrate, and a transparent electrode formed on the inner surface of the transparent substrate. a pair of formed electrodes, a pair of insulating films formed on the inner surfaces of the electrodes, including a transparent insulating film formed on the inner surfaces of the transparent electrodes, and an inner surface of at least one of the pair of insulating films. was formed.

A liquid crystal alignment film consisting of a base having in-plane anisotropy on the surface and a polyaddition polymer film or condensation polymer film excluding a ring-opening polymer formed directly on the in-plane anisotropy portion of the base, It is characterized by comprising a ferroelectric liquid crystal layer sealed in a space formed between a liquid crystal alignment film and the insulating film or between the liquid crystal alignment films.

Functions and Effects of the Third Invention The ferroelectric liquid crystal cell of the third invention has excellent memory properties.

In addition, when considering application to display devices, the ferroelectric liquid crystal cell is energy efficient, has a long liquid crystal life, can be driven at a lower voltage than other display devices, and is It is expected that its application fields will expand as it has superior orientation, has fewer microstructural defects, and can be made into a large area.

Although the mechanism by which the ferroelectric liquid crystal cell of the third invention achieves the above-mentioned effects is not yet clear, it is thought to be as follows.

In the ferroelectric liquid crystal cell of the third invention, for example, when a liquid crystal having a smectic C'' (S, nC'') phase is sealed in a cell having a cell gap narrower than the pitch of the helical structure, the liquid crystal molecules It becomes parallel to the surface of the substrate, and the orientation vector remains at an inclination angle θ with the layer normal direction of the S, C'' phase, and is defined in the surface direction of the substrate, and the helical structure disappears. When applied, the direction of spontaneous polarization is changed depending on the direction of the electric field, and the liquid crystal molecules move from the layer normal to
Switch in the direction of θ. For example, when a liquid crystal cell is sandwiched between a pair of orthogonal polarizing plates, the axis of the liquid crystal molecules is aligned with the optical axis of one polarizing plate when one of the cells is in a switch state. At this time, no light is transmitted and the state is dark; if the direction of the electric field is reversed while the position of the polarizing plate remains the same, the liquid crystal molecule axis and the optical axis of the polarizing plate are misaligned, and light is transmitted, resulting in a bright state.

As mentioned above, one of the features of FLC is its fast response speed. In order to increase the response speed, it is necessary that the viscosity of the liquid crystal be low and that the absolute value of the spontaneous polarization be large. On the other hand, FLC itself also has the feature of being able to ideally maintain its state even after the application of an electric field is stopped, that is, it has memory properties. Therefore, when considering application to a liquid crystal display device, even if the number of pixels is increased, a separate drive circuit for each pixel, such as a TPT, is no longer required, making it easier to increase the area. However, in the conventional technology, in order for FLC to have good memory properties, unless the absolute value of the spontaneous polarization component is 20 nC/cd or less, excellent memory properties cannot be achieved due to the alignment film, etc., and the response speed decreases. It was difficult to balance this with raising the number of employees. For this reason, one way to maintain the dark and bright states described above is to continue applying an electric field to the cell, but over a long period of time, the transmittance may decrease or the electric field may continue to be applied. The deterioration of the liquid crystal caused by this problem was a problem. In addition, in order to avoid a decrease in transmittance, it is possible to apply an electric field as pulses at short intervals, but in order to maintain transmittance, pulses must be applied continuously, which poses a problem of deterioration of the liquid crystal. It had become.

As a way to solve this problem, the above-mentioned L
A method using a lipolyimide film using Method B has been proposed, and it has been reported that memory properties have been achieved even for liquid crystals with high spontaneous polarization. However, since this LB method uses the aforementioned wet film formation, there is a risk of contamination by dust and contaminants, it is difficult to achieve a large area, and it is necessary to increase the number of accumulations to improve insulation, resulting in poor workability. There were problems such as poor orientation.

In the present invention, even when a liquid crystal with large spontaneous polarization and fast response speed is used, excellent memory performance is achieved that allows the transmittance to be maintained when the voltage is turned off after applying one pulse to the cell. It was possible to fabricate a ferroelectric liquid crystal cell with a ferroelectric liquid crystal cell having the same characteristics, and because the film was formed in a vapor phase, it was possible to solve the problems of the conventional method and the LB method described above.

Although the reason why the memory property appears has not been elucidated in detail, the weak interfacial interaction between the liquid crystal and the alignment film is attracting attention. For example, in a liquid crystal alignment film where a polyimide film is prepared using a spinner method or the like and its surface is rubbed, there is knowledge that the memory property improves as the intensity of the rubbing process is lowered. It is speculated that the deep grooves formed in the liquid crystal molecules strongly align the liquid crystal molecules in the rubbing direction, which is one of the reasons for hindering memory performance. However, it is difficult to perform weak rubbing with good reproducibility. In addition to the problem of disordered liquid crystal alignment, liquid crystal cells manufactured by performing a rubbing treatment still have various problems as described in the first invention.

In the present invention, a weak interfacial interaction between the liquid crystal and the alignment film is achieved by using a liquid crystal alignment film having an in-plane alignment polymeric thin film, which is different from the mechanism of rubbing the alignment film surface and aligning the liquid crystal, as the liquid crystal alignment film. As a result, it is thought that a ferroelectric liquid crystal cell with excellent memory properties could be created.

[Description of other inventions of the third invention] Below, other inventions of the third invention will be described.

In the ferroelectric liquid crystal cell of the third invention, the substrate, electrode, insulating film, and liquid crystal alignment film may be the same as those shown in the other invention section of the first invention.

Further, as the liquid crystal, a ferroelectric liquid crystal such as s, nc' liquid crystal is used.

In addition to the structure of the third invention, the ferroelectric liquid crystal cell of the present invention further includes a pair of substrates, at least one of which is a transparent substrate, and a transparent electrode formed on the inner surface of the transparent substrate. a pair of electrodes formed on the inner surface of the
A pair of electrodes each having a base having in-plane anisotropy on the inner surface of at least one of the electrodes, and a surface of the base having in-plane anisotropy on the inner surface of at least one of the pair of electrodes. An in-plane oriented polymer thin film that is directly formed and has electrical insulation properties and is made of a polyaddition polymer film or a condensation polymer film excluding a ring-opening polymer, and between the in-plane oriented polymer thin film, or between the in-plane oriented polymer thin film and the in-plane oriented polymer thin film. It can be configured by an insulating film formed on the inner surface of the electrode and a ferroelectric liquid crystal layer sealed in a space formed between the electrodes.

〔Example〕

The present invention will be explained in detail below.

Example 1 A silicon wafer and indium tin oxide transparent electrode coated glass were used as base materials, and a polyamide in-plane alignment polymer thin film was formed on the base materials by vapor deposition, and this was used as a liquid crystal alignment film to produce a liquid crystal cell according to the present invention. A liquid crystal cell was prepared and a performance evaluation test was conducted on the liquid crystal cell.

First, as a base material for a liquid crystal cell, a 2cm x 2°5cm
m indium tin oxide transparent electrode coach ink glass (
(hereinafter referred to as ITO) was prepared. In addition, a silicon wafer was prepared as a substrate for evaluating orientation using the IR method. One side of these substrates (and substrates) was covered with a polytetrafluoroethylene plate (critical surface tension: 18.5 dyn/cm).
) was rubbed 50 times in one direction to impart in-plane anisotropy. At this time, air is blown onto the part of the substrate (and substrate) that has been given in-plane anisotropy, and due to the anisotropy in the way the substrate (and substrate) is clouded, the rubbed surface of the substrate (and substrate) is It was confirmed that internal anisotropy was imparted.

Next, these base materials were placed in a vacuum device, heated and maintained at 62 to 65°C using a heater, and then heated to 1×1,0-'T.
It was evacuated to below orr (measured by an ion gauge).

Next, with the shutter closed, two monomer containers containing terephthalic acid chloride and decamethylene diamine were installed in a position facing the base material arranged in the vacuum device, and a container of terephthalic acid chloride was placed in the vacuum device. 35
Heat a container of decamethylene diamine to ~45°C.
Each was heated to ℃.

Next, while keeping the base material and monomer container temperatures at the above temperatures, the shutter of the decamethylene diamine container was fully opened, and then the terephthalic acid chloride container was partially opened to reduce the pressure inside the vacuum device to 5X 10-5 Torr or less. The degree of opening and closing of the shutter of the terephthalic acid chloride container was finely adjusted to achieve this.

Note that no matter which shutter was closed, an increase in pressure was observed when one of the shutters was open. Since the pressure fluctuates over time, the shutter of the terephthalic acid chloride container was finely adjusted every 10 to 30 minutes so that the pressure was at its lowest (at the beginning of film formation it was 5 × 1 (]” Torr or less, then 2 × 10 Torr or less). -'' Torr or less). In this state, 2-hour open film formation was performed to form a polymer film with a film thickness of approximately 6000 m on the substrate, thereby obtaining a liquid crystal aligning film.

An evaluation test for in-plane alignment of this liquid crystal alignment film was conducted by measuring a transmission IR spectrum.

The transmission IR spectrum of a polymer film (sample number 1) formed on a silicon wafer was measured using polarized light parallel and orthogonal to the rubbing direction under conditions of normal incidence on the polymer film. The results are shown in FIG. In the same figure, "11"
and “12” is the polarized IR spectrum of the polymer film, “
11'' is a spectrum obtained with polarization perpendicular to the rubbing direction, ``12'' is a spectrum obtained with polarization parallel to the rubbing direction, r From Fig. 7, it was found from these spectra that the polymer film had the structure of a polyamide film.Furthermore, as is clear from this difference spectrum, dichroism was observed, and the rubbing direction Since the absorption of carbonyl groups (1635 cm =) is stronger in the spectrum perpendicular to the direction of It was confirmed that an in-plane oriented polyamide film reflecting the above could be fabricated.

From the above results, it was confirmed that an in-plane oriented polymer thin film or an oriented film formed directly on the base could be produced.

Next, a liquid crystal cell was prepared using this in-plane aligned polyamide film as a liquid crystal alignment film, and the liquid crystal alignment ability of the cell was examined.

First, two of each of the above-mentioned liquid crystal alignment films were stacked with the polymer film facing the inner surface and parallel to the rubbing direction to produce a liquid crystal cell with a cell gap of 10 μm (sample number 2).
). This cell is kept at a temperature above the clear point of the liquid crystal, and a guest-host type liquid crystal (Phos) liquid crystal, Merck Z
L [-1,840, Dye: Mitsubishi Kasei (black dichroic dye, a mixture of several anthraquinone-based azo-based liquid crystals)
was enclosed. After cooling to room temperature, the alignment state of the liquid crystal was observed using a polarizer. As a result, it was found that a liquid crystal cell in which the liquid crystal was aligned parallel to the rubbing direction of the substrate could be manufactured.

For comparison, polyimide (manufactured by Toshi: 5P-910) was coated on an ITO substrate by a spinner method.
After heat treatment at 150°C, 200°C, and 250°C for 30 minutes each, the membrane surface was rubbed with a nylon brush, the cell was assembled in the same manner as above, and nematic liquid crystal was sealed to obtain a comparative liquid crystal cell (sample number CI). ). Regarding the alignment ability of this comparative liquid crystal cell, an observation test was conducted in the same manner as above.
Although the liquid crystal was oriented, it was observed that the orientation was disturbed due to dust that was thought to have been mixed in during film formation or heat treatment. In addition, it was observed that the orientation of the liquid crystal was disturbed even in areas such as scratches that appeared to have occurred during the rubbing process and unevenness during the rubbing process.

From the above results, it can be seen that the liquid crystal cell according to this example has a superior liquid crystal alignment ability compared to the comparative liquid crystal cell produced by a wet method. In addition, in the liquid crystal cell of this example, thousands of alignment films are vapor-deposited and polymerized on the rubbed base, so the surface of the alignment polymer film is free from unevenness and scratches due to grooves, and the liquid crystal molecules and the alignment polymer film are not scratched. Due to the anisotropy of the affinity between the polymer chains, the liquid crystal molecules are aligned in the most stable direction of the polymer chains, which is thought to result in excellent liquid crystal alignment ability.

Example 2 A polyamide film was formed on the base material under the same conditions as in Example 1, except that polyacrylonitrile and absorbent cotton were used instead of polytetrafluoroethylene as the rubbing material, and a liquid crystal alignment film was obtained. Ta.

Next, using this liquid crystal alignment film, liquid crystal cells were produced in the same manner as in Example 1, respectively. The liquid crystal alignment ability of each of the obtained liquid crystal cells was measured in the same manner as in Example 1. In the case of polyacrylonitrile (sample number 3), the direction was parallel to the rubbing direction, and in the case of absorbent cotton (sample number 4), the direction was parallel to the rubbing direction. It was found that the liquid crystal was oriented perpendicular to . From the above, the orientation direction of liquid crystals differed depending on the rubbing material.

Here, in order to investigate why the liquid crystal cell of the example has the liquid crystal alignment ability, an in-plane alignment evaluation test of the liquid crystal alignment film was conducted by measuring the transmission IR spectrum in the same manner as in Example 1.

The polarized IR spectrum of the polymerized thin film of the liquid crystal alignment film formed on the silicon wafer was measured in the same manner as in Example 1. The results are shown in FIG. In the figure, "31" indicates the results when polyacrylonitrile was used as the rubbing material (sample number 3'), and "41" indicates the results when absorbent cotton was used as the rubbing material (sample number 4'). show. As is clear from FIG. 8, when polyacrylonitrile was used as the rubbing material, an in-plane oriented polyamide film in which the polyamide polymer chains were oriented parallel to the rubbing direction was obtained, as in Example 1. Ta. Also,
When absorbent cotton is used as the rubbing material, dichroism opposite to that of polyacrylonitrile is observed, so an in-plane oriented polyamide film in which polyamide polymer chains are oriented in a direction perpendicular to the rubbing direction is obtained. That's what I found out.

From the above, it was found that the anisotropy of the in-plane oriented polymeric thin film was determined by the rubbing material, and that the orientation direction of the liquid crystal coincided with the anisotropic direction of the in-plane oriented polymeric thin film.

For comparison, a comparative liquid crystal cell was prepared in the same manner as in Example 1, except that the rubbing treatment was not performed, and the same performance evaluation test was conducted on sample number C2). As a result, in the case of this comparative liquid crystal cell, the liquid crystal alignment was random.

Example 3 Same as Example 1, except that a polyhydroxyethyl methacrylate plate, a polyvinyl alcohol sheet, and a filamentous polyacrylic acid were used instead of polytetrafluoroethylene as the rubbing material, and only an ITO substrate was used as the base material. Form a polyamide film on the substrate in the same manner as
A liquid crystal alignment film of this example was obtained.

Next, using this liquid crystal alignment film, liquid crystal cells were produced in the same manner as in Example 1 (sample numbers 5 to 7). The liquid crystal alignment ability of each of the obtained liquid crystal cells was measured in the same manner as in Example 1. When polyhydroxyethyl methacrylate plate and polyvinyl alcohol sheet were used as rubbing materials, polyacrylic acid was applied in parallel to the rubbing direction. It was found that when using this method, the liquid crystal was oriented in a direction perpendicular to the rubbing direction.

Example 4 First, liquid crystal was prepared in the same manner as in Example 1 except that absorbent cotton, polyacrylonitrile, and polytetrafluoroethylene were used as the rubbing material, and aromatic polyamide was used as the in-plane alignment polymerized thin film of the liquid crystal alignment film. An alignment film was prepared. Paraphenylene diamine was used instead of decamethylene diamine as a monomer, and the substrate temperature was 50 °C.
The temperature of the container of paraphenylenediamine was lowered to 750°C while lowering the temperature to ~35°C over 1 hour and keeping it at this temperature for 2 hours.
By adjusting the shutter of the terephthalic acid chloride container with the shutter of the paraphenylenediamine container fully open while maintaining the temperature at ℃ to 85°C, the amount of terephthalic acid chloride supplied is supplied in excess of the amount of paraphenylenediamine supplied. Then, the pressure during film formation polymerization was set to 5 to 1 OX 1
．． A liquid crystal alignment film was produced in the same manner as in Example 1 except that the vapor deposition treatment was performed for 3 hours while maintaining the temperature at 0-5 Torr.

Note that if the supply amount of terephthalic acid chloride is excessive, the pressure will decrease if the supply amount is reduced at the appropriate time, that is, if the shutter is slightly closed, and if the shutter of the paraphenylenediamine container is closed, the pressure will become monotonous. This was confirmed by the fact that it rises and then monotonically falls when it opens again.

In-plane alignment evaluation trial of these liquid crystal alignment films (silicon wafer: sample number 8' to 10') and liquid crystal alignment ability test of liquid crystal cell using the liquid crystal alignment film CITO substrate: sample number 8
-10) were performed in the same manner as in Example 1. As a result, both of these liquid crystal alignment films are in-plane anisotropic polymerized thin films in which the main chains are aligned in the same direction as the rubbing direction, and in liquid crystal cells using these liquid crystal alignment films, the liquid crystal has the above-mentioned anisotropy. It was found that they were oriented in the same direction.

Example 5 ITO transparent electrode coated glass was used as the base material, its surface was rubbed with a polytetrafluoroethylene plate, and a polyamide in-plane oriented polymer thin film was formed on the base material by vapor deposition, with a thickness of 2 μm. Assemble the liquid crystal cell and use ferroelectric liquid crystal (Merck: ZLI-3489).
) was sealed to produce a liquid crystal cell of this example, and a performance evaluation test of the liquid crystal cell was conducted (sample number 11.).

First, the liquid crystal cell was placed under crossed nicols of a polarizing microscope, the lower electrode of the liquid crystal cell was grounded, and a square wave of ±10 V was applied to the upper electrode. The liquid crystal cell was rotated so that it was darkest when −10 V was applied, and the optical axis was aligned and fixed (the darkest state when −10 V was applied was called the dark state, and the brightest state when +10 V was applied was called the bright state). The memory property is that this liquid crystal cell has positive and negative 4 values of 0 to ±IOV as shown in Figure 9.
Two continuous pulses were given and evaluated. The pulse width at this time is 0% in the dark state and 10096 in the bright state. After applying a voltage of -10 V to the liquid crystal and making it into the dark state, +lO
When a voltage of V was applied, the time was set to more than twice the time required to reach 0 to 90% (in this example, 0.5 m5ec). Note that the duty ratio was set to 1/20.

Among the four consecutive pulses, 91 pulses erase the information of the previous pulse voltage application and realize a dark state.
This is an OV erase pulse. The 92 pulses were write pulses for observing voltage dependence and were varied in steps from 0 to +IOV.

Basically, it is possible to check the operation and memory performance using these pulses 91 and 92, but if you continue to apply pulses of the same sign, there is a risk of deterioration of the liquid crystal cell, so to prevent this, 91 and 92 are used. Pulses 93 and 9□1 having the opposite sign and the same absolute value as each of 92 were applied, so that positive and negative voltages were always canceled out in the entire continuous pulse. The light passing through the liquid crystal cell at a point 95 at the end of the write pulse 92 and at a point 96 just before the next consecutive pulse was detected by a photomultiplier. FIG. 10 shows how the amount of transmitted light changes at points 95 and 96 when the write pulse 92 is varied from 0 to 1OV. In the figure, the vertical axis shows the ratio of the amount of transmitted light (transmittance) when the amount of light when the polarizing microscope is set to parallel Nicols without a liquid crystal cell is used as a reference (100%). In the same figure, rllllJ
is the transmittance at the time of writing (95 in Figure 9), [1
12J indicates the transmittance at the time of memory (96 in FIG. 9).

For comparison, polyimide (manufactured by Toshi: 5P-910) was coated on an ITO glass substrate using a spinner method, and the samples were heated at 150°C, 200°C, and 1250°C for 3 times each.
After heat treatment for 0 minutes, the membrane surface was rubbed with a nylon brush, the cell was assembled in the same manner as above, and the same liquid crystal was sealed to obtain a comparative liquid crystal cell (sample number C3). Regarding the alignment ability of this comparative liquid crystal cell, we conducted an observation test in the same manner as above, and found that although the liquid crystal was oriented, the alignment was disordered. was observed to be disordered.

Furthermore, a memory test was conducted in the same manner as above.

The results are shown in FIG. In the figure, rc31J indicates the amount of transmitted light during writing, and rc32'' indicates the amount of transmitted light during memory.

As is clear from FIG. 10, in the liquid crystal cell of this example, when the write pulse is less than 3cm, the influence of the erasing pulse is large, and the dark state written by the erasing pulse is memorized. It has been found that at voltages of 3 or more, a memory property with high transmittance begins to be obtained, and at voltages of 8 or more, a bright state with a transmittance equal to or higher than that when a write pulse is applied is memorized.

On the other hand, in the comparative liquid crystal cell shown in FIG. 11, when the erasing pulse 91 is applied, the transmittance is in a dark state of several percent, but when the write pulse 92 is 0. The transmittance of "C32", which exhibits memory properties, has already increased to 17% just 0.5 m5ec after stopping the application of the erasing pulse and the voltage. Since it is an intermediate value of the state,
It can be seen that there is no memory property at all.

The FLC used in this example, ZLI-3489, has a relatively large spontaneous polarization catalog value of 33 nC/cnr and a fast response speed. In this example, such an FLC
Since it exhibits excellent memory properties, it is expected to have a wide range of applications as a ferroelectric liquid crystal cell.

Furthermore, the liquid crystal cell of the present invention utilizes the phenomenon that the memory state differs depending on the magnitude of the voltage, and by changing the voltage, the brightness in the memory state can be arbitrarily manipulated, making it possible to display gradations. .

Example 6 A liquid crystal cell was produced in the same manner as in Example 5, except that polyacrylonitrile, absorbent cotton, and polyacrylic acid were used as the rubbing material when producing a liquid crystal alignment film (sample numbers 12 to 14). The memory properties of the liquid crystal cell were evaluated in the same manner as in Example 5 except that the pulse width was 1 ms.

The results of the memory test are shown in Figure 12 for the liquid crystal cell using polyacrylonitrile as the rubbing material (sample number 12), and for the liquid crystal cell using absorbent cotton (sample number 13).
The liquid crystal cell using polyacrylic acid (sample number 14) is shown in FIG. 13 and in FIG. 14, respectively.

In the figure, "121", rl, 3N, r141J indicate the amount of transmitted light during writing, rl, 22. +, l-132,4
, "142" respectively indicate the amount of transmitted light at the time of memory.

As is clear from FIGS. 12 to 14, all liquid crystal cells exhibited good memory properties, and especially when the voltage was high, the memory was brighter than the write time.

Example 7 The same procedure as Example 5 was performed, except that when producing a liquid crystal alignment film, the rubbing materials were polyacrylonitrile and polyacrylic acid, and the in-plane alignment polymerized thin film was the aromatic polyamide film used in Example 4. 16). For cells using polyacrylonitrile as the rubbing material, the erase pulse is
V, write pulse O~20V, pulse width 0.2ms
The cell using polyacrylic acid as a rubbing material was prepared under the same conditions as in Example 5, except that the erase pulse was IOV, the write pulse was 0-10 V, and the pulse width was 0.6 ms. Memory performance was evaluated.

The results of the memory test are shown in FIG. 15 for a liquid crystal cell using polyacrylonitrile as a rubbing material (sample number 15) and in FIG. 16 for a liquid crystal cell using polyacrylic acid (sample number 16). In the figure, r
151" and "161" indicate the amount of transmitted light during writing,
r152j, r162'' respectively indicate the amount of transmitted light during memory.

As is clear from FIGS. 15 and 16, it can be seen that all liquid crystal cells exhibit good memory properties. Also,
When polyacrylic acid is used as the rubbing material, since the transmittance of the cell during memory changes in stages, it is possible to display even finer gradation than when using a polyamide film.

[Brief explanation of drawings]

1 to 6 are schematic diagrams showing specific examples of the structure of the liquid crystal cell of the present invention, and FIG. 7 is a polarized IR spectrum of the liquid crystal alignment film obtained in Example 1 and its difference spectrum (in the rubbing direction). Orthogonal polarization spectrum - parallel polarization spectrum)
8 is a diagram showing the difference spectrum of the polarized IR spectrum of the liquid crystal alignment film obtained in Example 2, and FIGS. 9 to 1.1 are diagrams showing the difference spectrum of the polarized IR spectrum of the liquid crystal alignment film obtained in Example 2. Regarding the performance evaluation test, Figure 9 is a diagram showing the voltage pattern applied to the liquid crystal cell in the memory property test, Figure 1O is a diagram showing the memory property test results, and Figure 11 is a diagram showing the voltage pattern applied to the liquid crystal cell in the memory property test.
Diagrams showing the memory test results of Figures 12 to 1
Figure 4 relates to the performance evaluation test of the liquid crystal cell obtained in Example 6, Figure 12 is a line diagram showing the memory property test results of sample number 12, and Figure 13 is a line diagram showing the memory property test results of sample number 13. Figure 14 is a diagram showing the memory property test results of sample number 14, Figures 15 and 16 relate to the performance evaluation test of the liquid crystal cell obtained in Example 7, and Figure 15 is a diagram showing the memory property test results of sample number 15. Diagram showing the memory test results. FIG. 16 is a diagram showing the memory test results for sample number 16. At, A2, A3, A4, A4', A5, A5'
, A6, A6'...Transparent substrate aLa2, C3.
...Substrates B1, B2, B3, B4, B4', B5, B5'
, B6, B6'...transparent electrodes bl, b2, b3
...electrodes C1, C2, C3, C4, C4', C5, C5',
C6, C6'...Transparent insulating film c1, C2, C3.
...Insulating film DiXDi', B2, B3, B4, D4'D5, B6
, D6'...Transparent alignment film D61...Base B62...In-plane alignment polymerized thin film E1, B2, B3, B4, B5, B6...Liquid crystal +1.12.13...Sample number 1 31 ...Sample number 3゜41 ...Sample number 4' 1 11 ...Sample number 2 21 ...Sample number 3 32 ...Sample number 4 42 ...Sample number 5 52 ...Sample number 6 162 ... Sample number Figure 1 Figure 2

Claims (3)

[Claims] (1) a pair of substrates, at least one of which is a transparent substrate; a pair of electrodes formed on the inner surface of the substrate, including a transparent electrode formed on the inner surface of the transparent substrate; and an inner surface of the transparent electrode. a pair of insulating films formed on the inner surface of the electrode, including a transparent insulating film formed on the electrode; and a surface having in-plane anisotropy formed on the inner surface of at least one of the pair of insulating films. a liquid crystal alignment film comprising a base and a polyaddition polymer film or a condensation polymer film excluding a ring-opening polymer formed directly on the in-plane anisotropic portion of the base; and between the liquid crystal alignment film and the insulating film. , or a liquid crystal layer sealed in a space formed between the liquid crystal alignment films. (2) The liquid crystal alignment film is formed directly on a base portion having in-plane anisotropy on at least the surface thereof, and on the in-plane anisotropic portion of the base portion, and a surface formed on the in-plane anisotropic portion of the substrate. Polyaddition polymer membranes or degenerate polymers, excluding ring-opening polymers, formed by information on internal anisotropy being transmitted to the membrane surface in a form in which the orientation of the polymer main chain or functional group is in-plane anisotropy. 2. The liquid crystal cell according to claim 1, wherein the liquid crystal cell comprises a polymer film comprising a combined film. (3) a pair of substrates, at least one of which is a transparent substrate; and a pair of electrodes formed on the inner surface of the substrate, including a transparent electrode formed on the inner surface of the transparent substrate, at least one of the electrodes; a pair of electrodes each having a base having in-plane anisotropy on the inner surface of one of the electrodes; and at least one of the pair of electrodes having an inner surface formed directly on the surface of the base having in-plane anisotropy; An in-plane oriented polymer thin film made of a polyaddition polymer film or a condensation polymer film excluding a ring-opening polymer and having electrical insulation properties, and between the in-plane oriented polymer thin film, or between the in-plane oriented polymer thin film and the inner surface of an electrode. A liquid crystal cell comprising: a liquid crystal layer sealed in a space formed between an insulating film formed on a liquid crystal layer;