JPH0820641A - High-molecular liquid crystal and liquid crystal element - Google Patents

Abstract

PURPOSE:To obtain a high-molecular liquid crystal with the main chain consisting of polyoxetane, having specific recurring units, exhibiting high response rate to electric field change even at elevated temperatures, excellent in display characteristics for wide screens or curved screens, thus useful for electro-optical devices. CONSTITUTION:This high-molecular liquid crystal with the main chain consisting of polyoxetane is made up of recurring units of formula I (R is a substituent such as CH3; X is a group representing a sort of spacer such as an alkylene, ether-based divalent group or siloxane-based divalent group; Y is 4,4'-diphenylene or a group representing a core such as a group of formula II; Z is a chiral group-contg. terminal group) [e.g. a recurring unit of formula III (A is a substituent such as CH3 or halogen; (m) is 3-15; * denotes an asymmetric carbon atom)]. The number-average molecular weight of this liquid crystal is pref. 1000-1000000.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel ferroelectric polymer liquid crystal and liquid crystal element, and more particularly to a polymer liquid crystal and liquid crystal element suitable for displaying moving images.

[0002]

2. Description of the Related Art A liquid crystal display device is formed by sandwiching a liquid crystal film between a pair of electrode substrates. However, in order to manufacture a large-area liquid crystal display element, it is necessary to maintain a uniform cell gap over a large area and to use a ferroelectric liquid crystal.
There was a problem that it was difficult to manufacture. In order to solve such a problem, it has been proposed to use a ferroelectric liquid crystal polymer. For example, Japanese Unexamined Patent Publication (Kokai) No. 64-15722 proposes forming a liquid crystal film from a ferroelectric liquid crystal polymer such as a polyacrylate-based, polyether-based, polysiloxane-based, polyester-based or a copolymer thereof. ing.

The contents of each of the above ferroelectric liquid crystal polymers are described in JP-A-63-99204, 63-273608, 63-264629 and 63-2807.
42, JP-A No. 1-113424, and the like. Related to JP-A-63-264629 is JP-A-1-131234.

[0004]

However, among the conventional ferroelectric polymer liquid crystals, those having a polyacrylate-based or polyester-based main chain have a slow response speed to an electric field change, and the main chain has a polysiloxane-based liquid crystal. In the polyether type, the stable state of the liquid crystal of the chiral smectic C phase is poor at high temperature, which causes a problem that the response speed in the high temperature range is lowered.

Therefore, a main object of the present invention is to solve the above-mentioned technical problems and to provide a polymer liquid crystal having a fast response speed to an electric field change not only near room temperature but also in a high temperature region. Another object of the present invention is to provide a liquid crystal element applicable to a large screen or a bent screen.

[0006]

The polymer liquid crystal of the present invention for achieving the above object has polyoxetane as a main chain and has a repeating unit represented by the following general formula (I): It is a feature.

[0007]

Embedded image

(In the formula, R represents a substituent, X represents a spacer species group, Y represents a core portion group, and Z represents a terminal group containing a chiral group.) The liquid crystal device of the present invention A liquid crystal film containing a polymer liquid crystal having a repeating unit represented by the general formula (I) is sandwiched between substrates having a pair of electrodes. More specific examples of the oxetane-type polymer liquid crystal represented by the general formula (I) include those represented by the following general formula.

[0009]

Embedded image

(In the formula, X, Y, and Z are the same as above, A is a substituent, and m is an integer of 3 to 15.) Thus, the main chain of the polyether structure using polyoxetane The structure has less intramolecular rotation than conventional polyethers, and one mesogen unit exists for every four atoms (three carbon atoms and one oxygen atom) that make up the main chain. Therefore, the adjacent mesogens are relatively separated from each other, so that the interaction between the mesogens is small, the chiral smectic C phase is exhibited in a wide temperature range, and the fast response speed is exhibited.

Examples of the group serving as the spacer species shown by X include various groups such as alkylene series, ether series, and siloxane series as shown below, but the group X in the present invention is not limited thereto. Not something
Any group that can serve as a spacer species can be used.

[0012]

[Chemical 4]

(In the formula, m is the same as above, and n is an integer of 1 to 6.) As the core group represented by Y, a group having an aromatic ring is usually used. It is preferable in terms of chiral smectic property, and specific examples thereof include the groups shown below. In addition, it may contain a heterocycle such as a pyrimidine ring.

[0014]

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The terminal group containing a chiral group represented by Z is preferably a group in which a chiral group and a polar group having a high dipole moment are adjacent to each other in terms of orientation. Examples of the polar group include, for example, a carbonyl group represented by the above formula, a carbonyloxy group —COO—, and the like, and are not particularly limited. In addition, as the substituent A bonded to the asymmetric carbon atom, a bulky atomic group is desirable in consideration of ease of orientation, and for example, an alkyl group such as a methyl group, a halogen atom (fluorine, chlorine, bromine,
Iodine). In addition, in order to make the molecular chain more rigid, it is effective to introduce two or more chiral groups in order to enhance the orientation. Similarly, it is possible to introduce some polar groups, if desired.

The molecular weight of the polymer liquid crystal of the present invention is not particularly limited, but its number average molecular weight is 1,000 to 1,000.
It is preferably 10,000. Number average molecular weight is 1,0
When it is less than 00, the moldability as a film or a coating film is impaired, and when it exceeds 1,000,000, the electric field response becomes slower. The more preferable number average molecular weight of the polymer liquid crystal of the present invention is usually 5,000 to 50.
It is about 10,000, but is not limited to this.

The polymer liquid crystal monomer of the present invention can be synthesized, for example, according to the following reaction formula.

[0018]

[Chemical 6]

(In the formula, m and A are the same as the above.) That is, 3-bidroxymethyl-3-methyloxetane (1) is reacted with alkyl dibromide (2) to give a compound represented by the formula (3). To obtain the compound. This reaction is carried out in the presence of a catalyst in a suitable solvent containing a base such as sodium hydroxide. Examples of the solvent include hexane and tetrahydrofuran. Further, as the catalyst, for example,
TBAB (tetrabutylammonium bromide) and the like can be mentioned. After completion of the reaction, the product was isolated and purified, and reacted with p-hydroxybenzoic acid (4) in the presence of a base to give a compound of the formula
A compound represented by (5) is obtained. In this reaction, p-hydroxybenzoic acid (4) is converted to a sodium salt with sodium hydride NaH in a suitable solvent such as tetrahydrofuran, and an ether bond is formed. Then, the compound (5) is reacted with thionyl chloride to obtain the acid chloride (6).
By reacting the product (6) with the compound represented by the formula (7), the monomer represented by the above (8) can be obtained.

Since the obtained monomer (8) has cationic polymerizability, the polymer liquid crystal of the present invention can be obtained by carrying out cationic polymerization using a cationic polymerization catalyst such as BF ₃ . The polymer liquid crystal thus obtained may be used alone or, if necessary, mixed with a low molecular weight liquid crystal (eg nematic liquid crystal, smectic liquid crystal, chiral smectic liquid crystal, etc.), or may be mixed with an ordinary thermoplastic resin or thermosetting liquid crystal. A known film-forming method, for example, casting method, by mixing with a resin (for example, acrylic resin, silicone resin, urethane resin, epoxy resin, etc.) and various additives (for example, dichroic dye, electric field, ultraviolet absorber, etc.) The film can be formed by the T-die method, the inflation method, or the like. Further, the polymer liquid crystal of the present invention is a suitable solvent
It is also possible to form a film in a state of being in direct contact with the surface of the substrate by dissolving it in (for example, dichloromethane, acetone, a mixed solvent thereof, etc.), applying it on the surface of the substrate, and evaporating the solvent.

By sandwiching the molded polymer liquid crystal film as a liquid crystal film between two electrode substrates, it can be used as a liquid crystal element in various fields of optoelectronics such as liquid crystal displays, optical shutters and optical diaphragms. The polymer liquid crystal of the present invention has the characteristics that the liquid crystal state of the ferroelectric chiral smectic C phase is stable not only near room temperature but also at high temperature, and that it is easy to mold. It can be suitably used as a variety of electro-optical devices having the same.

Hereinafter, the polymer liquid crystal and the liquid crystal device of the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[0023]

EXAMPLE Using appropriate starting materials according to the above reaction scheme
To synthesize the monomer, and then BF ₃-Based cationic polymerization catalyst
Polymeric solution of the following formula:
Crystals (I) to (VI) were obtained.

[0024]

[Chemical 7]

[0025]

Embedded image

Each of the obtained polymer liquid crystals (I) to (VI) was formed into a film by a conventional method, and sandwiched between two glass substrates (electrode substrates) to form a liquid crystal element, which responded to a change in electric field. The speed was measured. Response speed is 30V applied voltage
Was given as a simple pulse with a pulse width of 200 μSec, and the time required for the transmittance to change from 10% to 90% was determined. Table 1 shows the results.

[0027]

[Table 1] From Table 1, it is confirmed that the polymer liquid crystal of the present invention has a high response speed.

[0028]

INDUSTRIAL APPLICABILITY As described above, the polymer liquid crystal of the present invention has a fast response speed to changes in the electric field not only near room temperature but also in a high temperature region, so that it is possible to display a moving image and further display a large screen or a bent screen. It can be suitably used as an element. Therefore, the liquid crystal element using the polymer liquid crystal of the present invention is useful as various electro-optical devices in the field of optoelectronics, and its industrial value is great.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G02F 1/141 (72) Inventor Koji Hara 1-3-1 Shimaya, Konohana-ku, Osaka Sumitomo Electric Industry Co., Ltd. Osaka Works (72) Inventor Toru Kashiwagi 1-3-3 Shimaya, Konohana-ku, Osaka Sumitomo Electric Industries Co., Ltd. Osaka Works

Claims (2)

[Claims] 1. A polyoxetane as a main chain having the following general formula:
A polymer liquid crystal having a repeating unit represented by (I). Embedded image (In the formula, R represents a substituent, X represents a spacer species,
Y represents a group serving as a core part, and Z represents a terminal group containing a chiral group. ) 2. A liquid crystal device comprising a liquid crystal film containing the polymer liquid crystal according to claim 1 sandwiched between substrates having a pair of electrodes.