JPS63129323A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain a large tilt angle by using a high polymer liquid crystal film which is obtained by orienting a liquid crystal type monomer applied on a substrate as an orienting film with a magnetic field and photopolymerizing it. CONSTITUTION:The liquid crystal type monomer 4 which is applied on the substrate 1 as the orienting film is oriented by the magnetic field and then photopolymerized to obtain the high polymer liquid crystal film, which is used. The liquid crystal monomer 4 is preferably a compound with a vinyl bond. It is important that the substrate 1 is slanted by an angle theta from the direction of lines of magnetic forces of magnets 2 and 3 to obtain the desired tilt angle theta. Consequently, the orienting film has liquid crystal property after the polymerization, liquid crystal charged in a cell can be oriented without any defect, and the high tilt is easily obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display element having an alignment film with a large tilt angle.

[Prior Art] Conventionally, in a twisted nematic (TN) type liquid crystal display element, liquid crystal is aligned underwater.

Organic polymer films such as polyimide, polyimide-isoindoroquinazoline, and polyimidebenzimidazene have been proposed as materials for the alignment film. In particular, in order to perform high-density display, a variety of alignment films with small tilt angles have been developed, as those with small tilt angles are suitable for this purpose.
The objective was almost achieved in terms of uniform alignment of liquid crystals, heat resistance, and insulation resistance.

For this, a diamine represented by the following general formula (II) and a tetracarboxylic dianhydride represented by the following general formula (m) are used as raw materials, and these are reacted to form a polyamic acid, which is then dehydrated. Polyimide was synthesized by ring closure.

H2N-R'-NH2(II) In this diamine, R' is phenylene.

Xylylene, naphthalene, diphenylene, etc. However, in recent years, T
, J., 5cheffer et al. (SID 85
In the super twisted nematic (STN) liquid crystal display device proposed by Digestp, 120-123 (1985), a large tilt angle is required.

For this reason, an oblique vapor deposition method that can easily obtain a high tilt angle has been adopted. However, the oblique vapor deposition method is expensive, uses a vacuum system, has poor productivity, and is not suitable for mass production of large liquid crystal display elements.

[Problems to be Solved by the Invention] Therefore, it has been desired to obtain an alignment film with a high tilt angle, high reliability, and good productivity.

[Means for Solving the Problems] The present invention has been made to solve these problems, and includes a pair of substrates on which an alignment film is formed on at least one substrate, and a sealing material around the pair of substrates. In a liquid crystal display element in which a cell is sealed and a liquid crystal is placed inside, a polymer liquid crystal obtained by photopolymerizing the liquid crystal monomer coated on the substrate as an alignment film is oriented by a magnetic field. The present invention provides a liquid crystal display element characterized by using a film.

A liquid crystal compound is a liquid crystal compound that can be polymerized by light or a radical catalyst. The liquid crystalline compound itself may exhibit liquid crystallinity, or may exhibit liquid crystallinity as a composition.

Any liquid crystal monomer may be used as long as it satisfies the above definition, but a compound having a vinyl bond is preferable, and specifically a compound represented by the general formula (I) is preferable.

(However, X represents a hydrogen atom or a methyl group, and R represents a fullkylene group with a chain length of 5 to 10. The methylene group therein may be substituted with oxygen, but the oxygen atom and the oxygen atom may be directly or Also, AI is not adjacent via one methylene group.

A2+A3 respectively represent a 1,4-disubstituted phenylene group and a trans-1,4-disubstituted cyclohexylene group,
m, n, p each represent an integer of 0 or l; intestine, n,
Two or more of p cannot be O.

BI32 is -COO-, -0CO-, -CH2-CH2
- or indicates a single bond. (Dl represents an alkyl group having 1 to 12 carbon atoms, an alkoxy group, or a cyan group), and a divinyl compound such as divinylbenzene may be added to increase the molecular weight of the alignment film. The liquid crystalline polymer is coated as it is or mixed with a liquid crystalline polymer, a solvent, or a non-liquid crystalline polymer to have a viscosity of 100 cps or more and 10,000 cps or less, on a transparent electrode-equipped substrate such as ITO. The thickness is preferably 100 to 2000 people.

A magnetic field is used to control the orientation of the liquid crystalline monomer coated in this way, and as shown in FIG. It is important to tilt the magnetic field by an angle θ from the direction of the magnetic field lines. The strength of the magnetic field may be at least 5 Gauss. The polymerization of liquid crystalline 7-mer-4 may be carried out in the magnetic field, or the polymerization may be carried out separately after being removed from the magnetic field.
By carrying out photopolymerization using a photopolymerizable liquid crystal monomer, it is simple and the orientation is less likely to be disturbed.

In addition, this substrate usually has an electrode on the substrate, specifically an I
Transparent electrodes made of TO (indium oxide-tin oxide) or tin oxide, opaque electrodes made of chromium, aluminum, etc. are formed. Furthermore, an undercoat film such as an insulating film, a polarizing film, a color filter film, etc. for the purpose of preventing elution of alkali from the substrate may be formed under this electrode, and an insulating film, a color filter film, etc. may be formed on the electrode. , an overcoat film such as a light transmission prevention film may be formed. These electrodes may have a two-layer structure with an insulating film interposed therebetween, or an active element such as a TPT or a non-linear resistance element may be formed. For these electrodes, undercoat, overcoat, and other structures inside the cell, conventional structures of liquid crystal display elements can be used.

The substrate thus formed is used to form a cell, liquid crystal is injected into the cell, and the injection port is sealed. As the liquid crystal to be sealed, in addition to a normal nematic liquid crystal, various liquid crystals such as a dichroic dye-added liquid crystal and a ferroelectric liquid crystal (SmC" liquid crystal) can be used.

In addition, on the outer surface of the liquid crystal cell manufactured in this way, characters, figures, light-opaque layers, color filters, etc. may be printed, a non-reflective layer may be formed, or a polarizing film may be applied as necessary. Laminate them and arrange reflectors, light guide plates, and lighting.

In addition, in the present invention, since a high tilt angle can be obtained, it is suitable for applications where the liquid crystal is largely twisted. Therefore, it is suitable for a liquid crystal display element in which the alignment processing directions of the alignment films of a pair of substrates are twisted by 160 to 360 degrees.

Furthermore, a pair of polarizing films are arranged on both outer surfaces of this substrate,
Each polarization axis is 20~
Spur twisted nematic (ST
N) Suitable for use in LCDs.

That is, by setting the twist angle of the liquid crystal to 1eO to 360° and using the high tilt angle orientation 11 of the present invention, it is possible to easily obtain a liquid crystal display element that does not cause alignment abnormalities and has high contrast. As the liquid crystal used in this 5TN LCD, a liquid crystal with positive dielectric anisotropy is used, and it may be created by mixing various liquid crystals.

[Example] Examples and comparative examples will be described below.

In these Examples and Comparative Examples, the tilt angle was measured using the Hc-0 method when the tilt angle was 5° or less;
When the angle was 5° or more, the magnetic null method was used.

70 mol% of the compound of Example 1 was dissolved in the formula Zen, and azobisisobutyronitrile was added to give 7
Polymerization was carried out at 0°C for 10 hours. Thereafter, it was reprecipitated from methanol to obtain a white liquid crystal polymer.

6.7 mol% of this liquid crystal polymer, 63 mol% of the compound of formula, 3 mol% of divinylbenzene, and 0.3 mol% of benzophenone.
Make a mixture of mol% and add it to the ITO glass plate.
applied to the surface. This was placed in a magnetic field of If (K Gauss) with an inclination angle of 30°, and irradiated with a high-pressure mercury lamp for 15 minutes.The ITO-coated glass coated with a polymer liquid crystal film with a controlled orientation of 1000 mm in thickness was thus A plate was obtained. These two glass plates were sandwiched to make a cell, and Merck's liquid crystal ZLI-2293 was sealed in the cell. The tilt angle was measured to be 27°. The polymer showed nematic liquid crystallinity even after polymerization, and the encapsulated i-product had good orientation. [Effects of the Invention] In the present invention, after the liquid crystalline monomer is oriented by a magnetic field, it is photopolymerized. The alignment film exhibits liquid crystal properties even after polymerization, and the liquid crystal sealed in the cell can be aligned without defects, making it easier to achieve a high tilt angle compared to conventional alignment films. Since the STN of the contrast is obtained
A liquid crystal display element can be easily obtained.

[Brief explanation of the drawing]

FIG. 1 is a side view illustrating the process of forming an alignment film of a liquid crystal display element of the present invention. 1: Substrate, 2.3: Magnet, 4: Liquid crystal monomer. 2°−E;,゛

Claims (1)

[Claims] (1) In a liquid crystal display element in which a pair of substrates, at least one of which has an alignment film formed thereon, are sealed with a sealing material around the substrate to form a cell, and a liquid crystal is sealed inside, the alignment film is A liquid crystal display element characterized by using a polymer liquid crystal film obtained by photopolymerizing a liquid crystal monomer coated on a substrate, aligned by a magnetic field, and then photopolymerized.