JPH0774189B2 - Ferroelectric liquid crystal oligomer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ferroelectric liquid crystal oligomer having a specific chemical structural formula.

[Prior Art] Liquid crystal display devices are widely used for various digital displays of personal computers, calculators, watches and the like.

Conventionally, the nematic liquid crystal substances used in these liquid crystal display devices have drawbacks such as a slow electrolytic response speed and a high pixel density due to crosstalk generated during time division driving. On the other hand, in place of this, a ferroelectric low molecular weight liquid crystal compound having bistability and high-speed electrolytic response has been proposed (JP-A-56-107216, U.S. Pat. No. 4,36).
7,924 specification).

Further, by mixing two kinds of ferroelectric low-molecular liquid crystal compounds each having a helical twist direction opposite to each other and increasing the helical pitch, the cell thickness can be increased, and a large area can be achieved. Proposals have been made (JP-A-60-90290, JP-A-61-207486, etc.).

However, since the ferroelectric low molecular weight liquid crystal compound has a poor orientation, a complicated process is required to assemble an optical element.

In order to improve this orientation, it has been proposed to mix a ferroelectric low molecular weight liquid crystal compound and a ferroelectric high molecular weight liquid crystal compound (Japanese Patent Laid-Open Nos. 63-284291 and 63-2890).
90 publication).

However, even this proposal has a drawback that the compatibility is poor.

[Problems to be Solved by the Invention] Under these circumstances, the present invention has been made for the purpose of providing a liquid crystal substance having a fast response speed to an electric field, excellent alignment properties, and a large area. Is.

[Means for Solving the Problems] As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a ferroelectric liquid crystal oligomer having a specific chemical structure can achieve the object. The present invention has been completed based on this finding.

That is, the present invention has the general formula (In the formula, R _i is (CH ₃ ) ₂ (CN) C-, and R ¹¹ is And m is an integer of 1 to 3. Where R ¹¹ is Then m ≠ 3.

Further, k is an integer of 1 to 30, r is 0 or 1, R ² is —H, —CH ₃ or —Cl, R ⁵ is 0 (oxygen) or —COO—, and R is ⁶ is And Y is —COO— or —OCO— and R ⁷ is —COOR.
⁸ , -OCOR ⁸ , -OR ⁸ , -COR ⁸ or -R ⁸ , wherein R ⁸ is And R ¹⁰ is —CH ₃ , —Cl or —CN, and n and p are each an integer of 0-10. ) A ferroelectric liquid crystal oligomer having a repeating unit represented by: and a degree of polymerization of 2 to 4 is provided.

Examples of the R ⁷ group include 1-methylpropoxycarbonyl group, 1-methylbutoxycarbonyl group, 2-methylbutoxycarbonyl group, 2-methylpentyloxycarbonyl group, 3-methylpentyloxycarbonyl group, 4-methyl Hexyloxycarbonyl group, 6-methyloctyloxycarbonyl group, 2-chloropropoxycarbonyl group, 2-chlorobutoxycarbonyl group, 4-chloropentyloxycarbonyl group, 1-cyanopropoxycarbonyl group, 2-cyanopentyloxycarbonyl group , 1-methylpropoxy group, 1-methylbutoxy group,
2-methylbutoxy group, 2-methylpentyloxy group,
3-methylpentyloxy group, 4-methylhexyloxy group, 6-methyloctyloxy group, 2-chloropropyloxy group, 2-chlorobutoxy group, 4-chloropentyloxy group, 1-cyanopropyloxy group, 2- Cyanopentyloxy group, 2-methylbutanoyloxy group, 2
-Methylpentanoyloxy group, 3-methylpentanoyloxy group, 3-methylhexanoyloxy group, 4-methylhexanoyloxy group, 6-methyloctanoyloxy group, 2-chloropropanoyloxy group, 2-chloro Examples thereof include a butanoyloxy group, a 4-chloropentanoyloxy group, a 2-cyanobutanoyloxy group and a 3-cyanopentanoyloxy group.

In addition, an alkylene group (CH ₂ ) _n or (CH ₂ ) _P in R ³
As, for example, methylene group, dimethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group,
Examples thereof include nonamethylene group and decamethylene group.

Also, the general formula in R ⁸ As the chemically active group represented by, for example, (+)-1-
Methyl butyl, (+)-1-chlorobutyl, (+)-1
-Methylpentyl, (+)-1-methylhexyl,
(+)-1-chloropropyl, (+)-1-methylheptyl, (+)-1-cyanobutyl, (+)-1-methylpropyl, (+)-1-chloro-2-methylpentyl,
(+)-1-chloro-2-methylbutyl and the like can be mentioned.

The ferroelectric liquid crystal oligomer of the present invention has a degree of polymerization of 2-4. When the degree of polymerization exceeds 5, the electric field response speed becomes slower, and when mixed with the ferroelectric low molecular weight liquid crystal compound, the compatibility is poor and it is difficult to align the ferroelectric low molecular weight liquid crystal compound.

Hereinafter, a general method for producing the ferroelectric liquid crystal oligomer of the present invention will be described.

The ferroelectric liquid crystal oligomer of the present invention has the following general formula: (Here, R ² , R ⁵ , R ⁶ , k, and r have the same meanings as defined above.) Obtained by addition-polymerizing the monomer (A) represented by 2 to 4 .

The addition polymerization of the monomer (A) is radical polymerization.
Azobisisobutyronitrile is used as a radical polymerization initiator. Solution polymerization is used as the polymerization method.

In the polymerization reaction, in order to reduce the amount of polymer liquid crystal compound having a degree of polymerization of 5 or more and to obtain a large amount of liquid crystal oligomer having a degree of polymerization of 2 to 4, the amount of the polymerization initiator used with respect to the monomer is increased. And shortening the polymerization time are effective. When the polymerization reaction product contains a polymer liquid crystal compound having a degree of polymerization of 5 or more, the liquid crystal oligomer of 2 to 4 mer in the polymerization reaction product can be prepared by various known methods,
For example, it can be separated by fractionation by column chromatography.

The various monomers used in the above-mentioned polymerization method can be prepared by various methods, and the following ones can be given as examples.

The monomer (A) can be prepared by the following method.

In the above reaction formula, R ² , R ⁸ and k have the same meanings as defined above, R ¹¹ means a group in which R ⁷ group is removed from R ⁶ defined above, and X is halogen. Means an atom.

The monomer (A) can also be prepared by the following method.

In the above reaction formula, R ² , R ⁶ , k and X have the same meanings as defined above.

From the regulation of the phase transition temperature, it was confirmed that the liquid crystal oligomer of the present invention obtained by the above method realizes a chiral smectic C phase liquid crystal state at a temperature including around room temperature and has a fast response speed to an electric field. .

Incidentally, the liquid crystal oligomer of the present invention, if necessary, mixed with other polymers, various additives including stabilizers, plasticizers, etc., addition of additives such as organic compounds and metals, etc.,
Improvements can be made by various treatment methods well known in the art.

EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1 The following monomer (1) was synthesized by the following method.

Synthesis of compound (a) 0.21 mol (14.8 g) of acrylic acid and 0.23 mol (41.8 g) of tetramethylammonium hydroxide (pentahydrate) were added to DMF30.
After stirring in 0 ml for 2 hours to form a uniform solution, 0.21 mol (77.4 g) of 1,12-dibromododecane was added, and the mixture was stirred for further 10 hours. Then, water 300 was added to the reaction solution, which was then extracted with ether and purified by column chromatography.
24.6 g (yield 37%) of the target compound (a) was obtained.

Synthesis of Compound (b) 4′-Hydroxybiphenyl-4-carboxylic acid 93 mmol (20 g) and (S)-(−)-2-metalbutanol 467 mmol (41 g) were added to benzene 1 in the presence of agricultural sulfuric acid 2 ml.
Refluxed in 50 ml for 25 hours. Then, the reaction solution was concentrated and recrystallized from a mixed solvent of toluene-hexane to give compound (b) [mp.116.2-117.8 ° C, [α] ²³ _D = + 4.35 ° (CH
Cl ₃ )] 26.0 g (yield 98%) was obtained.

Synthesis of Monomer (1) 15.8 mmol (5.0 g) of compound (a) above, 14.2 mmol (4.0 g) of compound (b) above and potassium carbonate 56.8
The mmol (7.9 g) mixture was refluxed in acetone for 16 hours. The reaction mixture was filtered and concentrated, and then recrystallized from ethanol to obtain the desired monomer (1) [[α] ²³ _D = + 2.7.
9 ° (CHCl ₃ )] 3.7 g (yield 50%) was obtained.

Preparation of Ferroelectric Liquid Crystal Oligomer (I) Next, 2.3 mmol (1.20 g) of the monomer (1) was added to 50 ml of azobisisobutyronitrile in 5 ml of tetrahydrofuran.
Was used as a polymerization initiator and reacted at 65 ° C. for 5 hours. The reaction mixture was purified by column chromatography to obtain 0.85 g of the ferroelectric liquid crystal oligomer (I). The conversion rate was 71%, and the average degree of polymerization of the liquid crystal oligomer was 3.3. The nuclear magnetic resonance analysis data of the liquid crystal oligomer is shown below, and the phase transition, electric field response speed and spontaneous polarization value are shown in Table 1.

Nuclear magnetic resonance analysis data ¹ H-NMR The phase transition, electric field response speed and spontaneous polarization value were measured by the following methods.

Confirmation of phase transition It was performed by observation with a polarizing microscope.

Measurement of electric field response speed A cell having a thickness of 2 μm was applied with ± 20 V, and the time required for change from light to dark or dark to light was measured.

Measurement of Spontaneous Polarization Value A cell having a thickness of 10 μm was applied with a voltage having a peak value of 200 V and changing in a triangular waveform, and spontaneous polarization was obtained from the signal of the polarization reversal current observed at this time.

Example 2 The following monomer (2) was synthesized by the following method.

Synthesis of compound (c) 0.2 mol (37.2 g) of 4,4'-dihydroxybiphenyl and 0.1 mol (12.0 g) of (S)-(+)-2-methylbutyryl chloride were stirred in 100 ml of pyridine for 3 hours. Water was added to the reaction solution, which was extracted with ether, and then purified by column chromatography to give 16.8 g of compound (c) (yield 79
%) Was obtained.

Synthesis of Monomer (2) 40 mmol (12.8) of compound (a) obtained in Example 1
g), a mixture of 40 mmol (8.6 g) of the above compound (c) and 0.2 mol (27.8 g) of potassium carbonate in acetone.
Reflux for hours. The reaction mixture is filtered and concentrated, and then recrystallized from ethanol to obtain the desired monomer (2) [[α]
²³ _D = + 7.83 ° (CHCl ₃ )] 9.6 (yield 53%) was obtained.

Preparation of Ferroelectric Liquid Crystal Oligomer (II) Next, 2.0 mmol (1.01 g) of monomer (2) was added to toluene.
It was dissolved in 5 ml, carbon tetrabromide (3.3 mg) and azobisisobutyronitrile (13 mg) were added to the solution, and the mixture was reacted at 70 ° C. for 5 hours. The reaction product was purified by column chromatography to obtain 0.60 g of a ferroelectric liquid crystal oligomer (II).
The conversion rate is 59% and the average degree of polymerization of the liquid crystal oligomer is 3.
Was 2. The nuclear magnetic resonance analysis data of the liquid crystal oligomer are shown below, and other physical properties are shown in Table 1.

Nuclear magnetic resonance analysis data ¹ H-NMR Example 3 The following monomer (3) was synthesized by the following method.

Synthesis of compound (d) 4- (11-undecyloxybromide) benzoic acid 80 mmol (29.71 g) was dissolved in chloroform 80 ml, thionyl chloride 160 mmol (19.04 g) was added to the solution, and the mixture was heated under reflux to 2 I went on time. Next, excess thionyl chloride and chloroform were distilled off under reduced pressure, and the residue was dissolved in 80 ml of tetrahydrofuran. This solution was added dropwise to a solution prepared by dissolving 80 mmol (14.42 g) of 4- (2-methylbutyloxy) -phenol in 160 ml of tetrahydrofuran and further stirring at room temperature for 6 hours.

The solvent was distilled off from the reaction mixture under reduced pressure, and dichloromethane was added for extraction. After washing this dichloromethane solution with water,
It was dried over magnesium sulfate. The solvent was distilled off under reduced pressure, and the residue was purified by column chromatography to obtain 19.21 g of the desired compound (d). The yield was 45%.

Synthesis of Monomer (3) A solution of 30 mmol (2.58 g) of methacrylic acid and 30 mmol (5.45 g) of tetramethylammonium hydroxide pentahydrate in 60 ml of dimethylformamide was added to 30 mmol (16.01 g) of dimethylformamide of compound (d). A 300 ml solution was added dropwise, and the mixture was stirred at room temperature for 12 hours. After completion of the reaction, the reaction mixture was poured into water and ethyl ether was added for extraction. After washing with diluted hydrochloric acid and water, the organic layer was dried over magnesium sulfate and the solvent was distilled off under reduced pressure to obtain a white solid. The white solid was recrystallized from ethanol to obtain 12.13 g of Monomer (3). The yield was 75%.

Production of ferroelectric liquid crystal oligomer (III) Monomer (3) 20 mmol (10.78 g) in a glass ampoule,
0.3 mmol (0.04 g) of azobisisobutyronitrile and 20 ml of dry tetrahydrofuran were added, and the mixture was freeze-deaerated and replaced with argon, and then sealed. After reacting at 60 ° C. for 8 hours, the ampoule was opened. The solvent was removed from the reaction mixture under reduced pressure, and the residue was purified by column chromatography to obtain 7.55 g of a ferroelectric liquid crystal oligomer (III). The average degree of polymerization of the liquid crystal oligomer was 3.1. The nuclear magnetic resonance analysis data of this liquid crystal oligomer are shown below, and other physical properties are shown in Table 1.

Nuclear magnetic resonance analysis data ¹ 1H-NMR Example 4 The following monomer (4) was synthesized by the following method.

Synthesis of Monomer (4) A method similar to the synthesis method of Monomer (3) of Example 3 except that 2-chloroacrylic acid was used instead of methacrylic acid in the synthesis of Monoer (3) of Example 3. And the monomer (4) was synthesized. The yield was 68%.

Production of Ferroelectric Liquid Crystal Oligomer (IV) Ferroelectric liquid crystal oligomer of Example 3 except that monomer (4) was used instead of monomer (3) in the production of ferroelectric liquid crystal oligomer of Example 3. Ferroelectric liquid crystal oligomer (IV) was produced in the same manner as in the production method of. The average degree of polymerization of the liquid crystal oligomer was 3.7. The nuclear magnetic resonance analysis data of this liquid crystal oligomer is shown below,
Other physical properties are shown in Table 1.

Nuclear magnetic resonance analysis data ¹ 1H-NMR [Effects of the Invention] According to the configuration of the present invention described above, a ferroelectric liquid crystal oligomer having a fast response speed to an electric field, a wide temperature range in which a liquid crystal can be used, and excellent film-forming orientation is obtained. To be Therefore, the area can be increased and the productivity of the liquid crystal element can be improved.

The ferroelectric liquid crystal oligomer of the present invention is used for display devices such as watches and calculators, electronic optical shutters, electronic optical diaphragms, optical communication optical path changeover switches, optical modulators, liquid crystal printer heads,
It can be used in the field of optoelectronics such as various electro-optical devices such as memories and variable focal length lenses.

 ─────────────────────────────────────────────────── Continued from the front page (56) References JP 62-277412 (JP, A) JP 63-72784 (JP, A) JP 64-22918 (JP, A) US Patent 4661574 (US) , A)

Claims (1)

[Claims] 1. A general formula (In the formula, R _i is (CH ₃ ) ₂ (CN) C-, and R ¹¹ is And m is an integer of 1 to 3. Where R ¹¹ is Then m ≠ 3. Also, k is an integer of 1 to 30, r is 0 or 1, R ² is —H, —CH ₃ or —Cl, R ⁵ is O (oxygen) or —COO—, and R is ⁶ is And Y is —COO— or —OCO— and R ⁷ is —COOR.
⁸ , -OCOR ⁸ , -OR ⁸ , -COR ⁸ or -R ⁸ , wherein R ⁸ is And R ¹⁰ is —CH ₃ , —Cl or —CN, and n and p are each an integer of 0-10. ) A ferroelectric liquid crystal oligomer having a repeating unit represented by: and a degree of polymerization of 2 to 4.