JPH04241323A - Liquid crystal oriented film - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal element having excellent optical characteristics by mainly consisting the above film of a resin expressed by specific formula and an antistatic agent and rubbing the film. CONSTITUTION:This film is provided in the liquid crystal element formed by sealing a liquid crystal between electrode substrates 1 and 2 facing each other and consists mainly of the resin having the repeating unit expressed by formula I and the antistatic agent. The film is formed by being rubbed. In the formula I, R denotes a bivalent org. group. Then, the pretilt angle of the liquid crystal molecules is made relatively high if the perpendicular orienting material layer is formed nearly as a monomolecular layer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal alignment film. In particular, it relates to the orientation of liquid crystal molecules, which affects the characteristics of liquid crystal elements.

0002

2. Description of the Related Art A liquid crystal element is obtained by filling a gap between both substrates with a liquid crystal composition. In this case, the alignment film generally used is often composed of a single polyimide material.

The concept of alignment films for liquid crystal molecules is detailed in ``Fundamentals and Applications of Liquid Crystal Electronics'' edited by Akio Sasaki.

0004

[Problem to be solved by the invention] In nematic liquid crystal elements and ferroelectric liquid crystal elements, lowering the electrical resistance of the alignment film can lower the threshold voltage, and in the case of ferroelectric liquid crystal elements, alignment can be improved. In addition, it is desirable to be able to display a uniform liquid crystal element. However, conventional alignment films made of polyimide have high electrical resistance. In addition, for this purpose, attempts have been made to mix a charge transfer complex into a polyimide alignment film, but this means that the charge transfer complex is dissolved in the polyimide varnish. In other words, in order to achieve this dissolution, material constraints and
Or the molecular structure restrictions are very large and it is not realistic.

[0005] Generally, the pretilt angle of liquid crystal molecules is currently a little less than 10° with good uniformity. Depending on the mode of the liquid crystal element, it may be necessary to achieve a significantly higher pretilt.

[0006] In addition, varnish for polyimide alignment films is applied industrially by printing methods, but it is sometimes difficult to obtain a uniform coating film.

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a liquid crystal alignment film provided in a liquid crystal element in which liquid crystal is sealed between opposing electrode substrates,
The general formula is

[0008]

[Case 2]

The present invention discloses a liquid crystal aligning film which is mainly composed of a resin having a repeating unit represented by the following formula and an antistatic agent and is rubbed.

Further, the present invention provides a liquid crystal alignment film provided in a liquid crystal element formed by sealing a liquid crystal between opposing electrode substrates, which has a repeating unit whose general formula is represented by (Chemical formula 2). The present invention also provides a liquid crystal alignment film characterized by comprising a layer mainly composed of a resin and an antistatic agent, which are rubbed together, and a vertical alignment agent molecular layer provided thereon.

[0011] The present invention provides a liquid crystal alignment film provided in a liquid crystal element formed by sealing a liquid crystal between opposing electrode substrates, the film comprising a resin having a repeating unit whose general formula is represented by (Chemical formula 2). The present invention also provides a liquid crystal aligning film which is mainly composed of an antistatic agent, an antistatic agent, and a polyacrylonitrile resin, and is formed by rubbing.

The present invention relates to a liquid crystal alignment film provided in a liquid crystal element formed by sealing a liquid crystal between opposing electrode substrates, the film comprising a resin having a repeating unit whose general formula is represented by (Chemical formula 2). A liquid crystal alignment film is disclosed, which is characterized by comprising a layer mainly composed of an antistatic agent and a polyacrylonitrile resin, a layer formed by rubbing these, and a layer of vertical alignment agent molecules provided thereon.

[0013]

[Operation] A resin having a repeating unit represented by the general formula (Chemical formula 2) has more carbonyl groups than a general polyimide resin, and is assumed to have a correspondingly higher polarity. Therefore, the coatability of a varnish containing a resin having a repeating unit represented by (Chemical formula 2) to a substrate is generally superior to that of a polyimide resin. Note that for the resin varnish having a repeating unit represented by the general formula (Chemical formula 2), normal methyl 2-pyrrolidone, gamma butyl lactone, etc. are used as a solvent.

The alignment film or a part of the alignment film mainly consists of a resin having a repeating unit represented by (Chemical formula 2) and an antistatic agent, or mainly consists of the above resin, a polyacrylonitrile resin, and an antistatic agent. As a result, the electrical resistance of the alignment film is considerably reduced. This is inferred from the response threshold of liquid crystal molecules. In addition, compared to the difficulty in dissolving conventional charge transfer complexes in alignment films, many types of antistatic agents (also called antistatic agents) are available, and some are highly soluble and can be used for various purposes. It is easy to choose ones with good characteristics. Additionally, charge transfer complexes are generally thermally unstable. Also, many of them are colored, making them difficult to use as displays.

[0015] The general formula consists mainly of a resin having a repeating unit represented by (Chemical formula 2) and an antistatic agent, or mainly consists of the above resin, a polyacrylonitrile resin, and an antistatic agent,
Furthermore, if a vertical alignment agent layer is formed almost as a monomolecular layer on the rubbed layer, a pretilt of liquid crystal molecules of about 10° to 89° measured from the alignment film surface can be reproduced depending on the manufacturing conditions of the liquid crystal element. You can get it easily. In particular, if the polyacrylonitrile resin content is increased, the pretilt angle of the liquid crystal molecules can be made relatively high. This is suitable for liquid crystal devices using homeo-alignment and surface-stabilized ferroelectric liquid crystal devices.

[0016]

[Examples] Examples of the present invention will be described below.

(FIG. 1) is a sectional view showing a liquid crystal element obtained by an embodiment of the present invention. In the same figure, 1,
2 is, for example, a first and second substrate made of transparent glass; 3;
, 4 is a rectangular transparent conductive electrode made of, for example, an ITO film on the main surface, 5 and 6 are alignment films, and 7 is a liquid crystal layer.

(Example 1) The general formula has a repeating unit represented by (Chemical formula 2), and R is

[0019]

[Chemical formula 3]

A normal methyl pyrrolidone solution of a polymerized polyparabanic acid resin (trade name: Sollac) represented by the following was obtained from Tonen Petrochemical. In addition, as an antistatic agent, the trade name Eletat S was obtained from Hitoshisha Co., Ltd. A normal methyl pyrrolidone solution was prepared to contain about 0.5% by weight of the polyparabanic acid resin. Furthermore, with respect to this resin content, so that it is 1% by weight,
The antistatic agent was added to the normal methyl pyrrolidone solution. This solution was applied with a spinner to the main surfaces of glass substrates 1 and 2 having microfabricated ITO electrodes 3 and 4 as base materials, and heated (heating temperature was approximately 15°C).
(about 20 minutes). The film thickness was about 10 nm.

Next, a normal rubbing treatment was performed. Glass substrates 1 and 2 are bonded together with a predetermined gap between them so that the rubbing directions are antiparallel and their principal surfaces face each other. As the sealing resin, an epoxy resin that can be cured at about 150° C. for 3 hours was used.

Next, the gap is filled with a ferroelectric liquid crystal composition. Thus, a liquid crystal panel is obtained. A voltage is applied to the ITO electrode, and it is observed while being sandwiched between polarizing plates.

All initial orientations were uniform orientations. There were also very few zigzag defects. Conventionally, even if this state can be obtained, when a voltage is applied, the twisted orientation becomes dominant and the contrast is significantly reduced. However,
In this example, a stable bistable uniform orientation was obtained even when a voltage was applied. Naturally, the contrast has also been significantly improved compared to the previous model.

Regarding the bistable uniform orientation,
We were able to obtain sufficient reliability. This is something that could not have been expected in the past.

(Example 2) As antistatic agents, Eletat S (trade name) was obtained from Hitoshisha Co., Ltd., Elegan-264P was obtained from Nippon Oil & Fats Co., Ltd., and Dasper-125B was obtained from Miyoshi Oil Co., Ltd. Similarly to Example 1, a normal methyl pyrrolidone solution was prepared to contain about 0.7% by weight of the polyparabanic acid resin. Furthermore, the above-mentioned normal
Each of the above antistatic agents was added to the methyl pyrrolidone solution to obtain three types of normal methyl pyrrolidone solutions. Each of these solutions was applied with a spinner to the main surfaces of glass substrates 1 and 2 having microfabricated ITO electrodes 3 and 4 as base materials, and heated (heating temperature was approximately 15°C for approximately 20 minutes. ). The film thickness was about 10 nm. In this way, a substrate having three types of resin films is obtained.

The subsequent treatments were carried out for all three types of substrates. I did the normal rubbing process. Next, a vertical alignment agent, ZLI-3334 (manufactured by Merck & Co., Ltd.), was applied to the rubbed resin surface using a spinner. Three types of substrates are thus obtained.

Glass substrates 1 and 2 of the same type are bonded to each other with a predetermined gap so that their principal surfaces face each other so that the intersection angle of liquid crystal molecules is 250°. The sealing resin used was an ultraviolet curing resin. In addition, when irradiating ultraviolet light during curing, areas other than the seal were strictly masked.

A nematic liquid crystal composition is filled into the gap. A liquid crystal panel is thus obtained. A voltage was applied to the ITO electrode, which was sandwiched between polarizing plates to evaluate the uniformity of optical changes of the liquid crystal panel. Uniformity was improved by about 30% compared to the conventional one. The best results were obtained using Eretat S as the antistatic agent.

Next, the glass substrates 1 and 2 are bonded together with a predetermined gap so that the principal surfaces of the three substrates face each other so that the rubbing directions are antiparallel to each other. As the sealing resin, an epoxy resin that can be cured at about 150° C. for 3 hours was used.

Next, the gap is filled with a ferroelectric liquid crystal composition. Thus, a liquid crystal panel is obtained. A voltage is applied to the ITO electrode, and it is observed while being sandwiched between polarizing plates.

All initial orientations were uniform orientations. There were also very few zigzag defects. Conventionally, even if this state can be obtained, when a voltage is applied, the twisted orientation becomes dominant and the contrast is significantly reduced. However,
In this example, a stable bistable uniform orientation was obtained even when a voltage was applied. Naturally, the contrast has also been significantly improved compared to the previous model.

Regarding the bistable uniform orientation,
We were able to obtain sufficient reliability. This is something that could not have been expected in the past.

(Example 3) The polyparaban resin was added to about 0
．． 693% by weight, and about 0.007% by weight of polyacrylonitrile resin (obtained from Kanto Kagaku Co., Ltd.).
A methyl pyrrolidone solution was prepared. Next, 0.5% by weight of each of the above-mentioned antistatic agents, Eletat S, Elegan-264P, and Dasper-125B were added to the solution to obtain three types of solutions.

[0034] Experiments similar to those in Example 1 were conducted for each solution, and similar favorable results were obtained.

(Example 4) About 0.6% of polyparaban resin
93% by weight, approximately 0.007% polyacrylonitrile resin
A normal methyl pyrrolidone solution containing % by weight was prepared in the same manner as in Example 3. Next, 0.5% by weight of each of the above-mentioned antistatic agents, Eletat S, Elegan-264P, and Dasper-125B were added to the solution to obtain three types of solutions. Each of these solutions was applied with a spinner to the main surfaces of glass substrates 1 and 2 having microfabricated ITO electrodes 3 and 4 as base materials, and heated (heating temperature was approximately 15°C for approximately 20 minutes. ). The film thickness was about 10 nm. In this way, a substrate having three types of resin films is obtained.

The subsequent treatments were carried out for all three types of substrates. I did the normal rubbing process. Next, a vertical alignment agent, ZLI-3334 (manufactured by Merck & Co., Ltd.), was applied to the rubbed resin surface using a spinner. Three types of substrates are thus obtained.

[0037] For each solution, experiments similar to those in Example 2 were conducted, and similar favorable results were obtained.

[0038]

As described above, the present invention makes it possible to obtain an excellent liquid crystal element through appropriate processing, thereby greatly contributing to industry.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a liquid crystal element obtained by an example of the present invention.

[Explanation of symbols]

1, 2 First and second substrates 3, 4 Rectangular transparent conductive electrode 5 made of ITO film
, 6 alignment film 7 liquid crystal layer

Claims (4)

[Claims] Claim 1: A liquid crystal alignment film provided in a liquid crystal element formed by sealing a liquid crystal between opposing electrode substrates, comprising a resin having a repeating unit whose general formula is represented by [Chemical formula 1] and a charged A liquid crystal alignment film characterized by being mainly composed of an inhibitor and rubbed. 2. A liquid crystal alignment film provided in a liquid crystal element formed by sealing a liquid crystal between opposing electrode substrates, comprising a resin having a repeating unit whose general formula is represented by (Chemical formula 1) and a charged A liquid crystal alignment film characterized by comprising a layer consisting mainly of an inhibitor, a layer formed by rubbing this, and a vertical alignment agent molecular layer provided thereon. 3. A liquid crystal alignment film provided in a liquid crystal element formed by sealing a liquid crystal between opposing electrode substrates, comprising a resin having a repeating unit whose general formula is represented by (Chemical formula 1) and a charged resin. A liquid crystal alignment film that is mainly composed of an inhibitor and polyacrylonitrile resin and is formed by rubbing. 4. A liquid crystal alignment film provided in a liquid crystal element formed by sealing a liquid crystal between opposing electrode substrates, comprising a resin having a repeating unit whose general formula is represented by (Chemical formula 1) and a charged resin. A liquid crystal alignment film characterized by comprising a layer mainly composed of an inhibitor and a polyacrylonitrile resin and a layer formed by rubbing the same, and a vertical alignment agent molecular layer provided thereon.