JP2012057038A - Additive-containing liquid crystal composition, usage of the same, and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal composition containing an additive capable of improving a driving voltage and a response speed, to provide a usage of the liquid crystal composition, and to provide a liquid crystal display element containing the liquid crystal composition.SOLUTION: This liquid crystal composition includes: a complex in which a host compound having an inclusion function for a liquid crystal molecule is coupled to a metal oxide nanoparticle; and a compound represented by general formula (1-0) (wherein R is a 1-5C alkyl group or 2-5C alkenyl group; Aand Aare each independently a 1,4-phenylene group, trans-1,4-cyclohexylene group, or naphthalene-2,6-diyl group; the 1,4-phenylene group or naphthalene-2,6-diyl group has at least one F or Cl as an unsubstituted group or a substituted group; Zand Zeach independently denote a single bond, -COO-, -CFO-, or -(CH)-; Xand Xare each independently H, F, Cl, CFor OCF; and m is 0, 1 or 2).

Description

  The present invention relates to a liquid crystal composition containing an additive, a method for using the same, and a liquid crystal display device.

  In general, liquid crystal display elements are widely used in image display devices such as liquid crystal TVs, computer monitors, and mobile phones, information terminals, and games. However, the speed of displaying a moving image on the liquid crystal display element becomes slow because the change in orientation of the liquid crystal molecules is delayed from the applied waveform.

  In order to eliminate this delay and increase the moving image display speed, the present inventors have developed a technique using a liquid crystal layer in which metal nanoparticles are mixed with liquid crystal molecules (see Patent Document 1). Dispersion of the metal nanoparticles in the liquid crystal layer increases the dielectric constant. As a result, the delay in the change in orientation of the liquid crystal molecules is eliminated, and a high-speed response is possible.

  The present inventors have further developed and reported a composite in which a host compound having inclusion ability with respect to liquid crystal molecules and metal nanoparticles are bonded as a liquid crystal additive (Patent Document 2, Non-Patent Document). Reference 1). In such a liquid crystal additive, the dielectric constant is increased by the metal nanoparticles, and the viscosity is decreased by the host compound having the inclusion ability to the liquid crystal molecules, thereby eliminating the delay in changing the orientation of the liquid crystal molecules and increasing the response speed. Can do.

  The technique of adding the inclusion compound of liquid crystal molecules and cyclodextrin shown in Patent Literature 2 and Non-Patent Literature 1 to the liquid crystal layer improves the delay in the change in the orientation of the liquid crystal molecules, but has higher liquid crystal display characteristics. It has been demanded. In addition, as a performance required for a liquid crystal material containing an additive, it is desired that the liquid crystal material used for the liquid crystal display element exhibits stable dispersion over a long period of time.

JP 2005-148705 A JP 2009-053243 A

Yukihide Shiraishi, Nobuaki Okamura, Keisuke Kobayashi, Naoki Tojima, “Electro-optical properties of liquid crystal display elements added with cyclodextrin polymer-protected Rh nanoparticles”, “Polymer Preprint”, Japan, Vol. 56, no. 1, p. 1919 (2007)

  The present invention has been made in view of the circumstances as described above, and includes a liquid crystal composition including an additive for improving driving voltage and response speed, a method for using the same, and a liquid crystal display including the liquid crystal composition. An object is to provide an element.

  The inventors of the present invention have made extensive studies in order to solve the above-mentioned problems. As a result, the conventional metal nanoparticles are changed to metal oxide nanoparticles, and the inclusion ability of the metal oxide nanoparticles and liquid crystal molecules is improved. The present inventors have found that the above problem can be solved by adding a complex bonded with a host compound having a hydrogen atom to a liquid crystal layer of a liquid crystal display element, and the present invention has been completed. Specifically, the following liquid crystal composition and the like are provided.

（式中、Ｒは炭素原子数１〜５のアルキル基又は炭素原子数２〜５のアルケニル基を表し；Ａ_１及びＡ_２は各々独立的に１，４−フェニレン基、トランス−１，４−シクロへキシレン基又はナフタレン−２，６−ジイル基を表し、該１，４−フェニレン基又はナフタレン−２，６−ジイル基は非置換又は置換基として１個又は２個以上のＦ若しくはＣｌを有しており；Ｚ₁及びＺ_２は各々独立的に単結合、−ＣＯＯ−、−ＣＦ_２Ｏ−、又は−(ＣＨ_２)_２−を表し；Ｘ_１及びＸ_２は各々独立的にＨ、Ｆ、Ｃｌ、ＣＦ_３又はＯＣＦ_３を表し；ｍは０、１又は２を表す。）で表される化合物を含有する液晶組成物。
（２）前記ホスト化合物が、シクロデキストリン、アミロペクチン、クラウンエーテル、シクロファン、カリックスアレン、ククルビツリル、イソグアニン、シクロトリホスファゼン及びこれらの誘導体からなる群より選ばれる少なくとも１種である前記（１）記載の液晶組成物。
（３）前記金属酸化物ナノ粒子が、二酸化珪素、酸化チタン、酸化ジルコニウム、チタン酸バリウム及びジルコン酸バリウムからなる群より選ばれる少なくとも１種を含有する前記（２）又は（３）記載の液晶組成物。
（４）少なくとも一方が透明な２枚の基板間に液晶層が狭持された構造を有し、該液晶層に前記（１）から（３）の何れか一つに記載の液晶組成物を含むことを特徴とする液晶表示素子。
（５）前記基板間の距離（ｄ）が２〜５μｍの範囲である前記（４）記載の液晶表示素子。
（６）前記液晶組成物の複屈折（Δｎ）と前記基板間の距離（ｄ）の積が０．３〜０．４μｍの範囲である前記（５）記載の液晶表示素子。 (1) A complex in which a host compound having an inclusion ability for liquid crystal molecules is bonded to metal oxide nanoparticles, and a general formula (1-0)

(In the formula, R represents an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms; A ₁ and A ₂ are each independently a 1,4-phenylene group, trans-1,4; -Represents a cyclohexylene group or a naphthalene-2,6-diyl group, and the 1,4-phenylene group or naphthalene-2,6-diyl group is unsubstituted or substituted with one or more F or Cl Z ₁ and Z ₂ each independently represents a single bond, —COO—, —CF ₂ O—, or — (CH ₂ ) ₂ —; each of X ₁ and X ₂ independently represents H, F, Cl, CF ₃ or OCF ₃ ; m represents 0, 1 or 2).
(2) The host compound is at least one selected from the group consisting of cyclodextrin, amylopectin, crown ether, cyclophane, calixarene, cucurbituril, isoguanine, cyclotriphosphazene and derivatives thereof. Liquid crystal composition.
(3) The liquid crystal according to (2) or (3), wherein the metal oxide nanoparticles contain at least one selected from the group consisting of silicon dioxide, titanium oxide, zirconium oxide, barium titanate and barium zirconate. Composition.
(4) A liquid crystal layer is sandwiched between two substrates, at least one of which is transparent, and the liquid crystal composition according to any one of (1) to (3) is disposed on the liquid crystal layer. A liquid crystal display element comprising:
(5) The liquid crystal display element according to (4), wherein the distance (d) between the substrates is in the range of 2 to 5 μm.
(6) The liquid crystal display element according to (5), wherein the product of birefringence (Δn) of the liquid crystal composition and the distance (d) between the substrates is in the range of 0.3 to 0.4 μm.

  The liquid crystal composition of the present invention can change driving voltage and response speed to good performance. For this reason, a liquid crystal display element having a high-speed response can be realized by using the liquid crystal composition. In addition, the liquid crystal composition of the present invention has a more improved dispersion of the composite in the liquid crystal composition than the liquid crystal composition containing the composite of the conventional metal nanoparticles and the host compound.

It is a conceptual diagram which shows the one aspect | mode of the manufacturing method of the composite_body | complex of the host compound and metal oxide nanoparticle of this invention, and the composite_body | complex added. It is a conceptual diagram which shows the one aspect | mode of the liquid crystal display element of this invention. The liquid crystal molecules are controlled to be in a state A or a state B by applying electricity to an alignment film provided on the substrate and an electrode provided on the substrate.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. can do.

[Liquid crystal display element]
FIG. 2 shows a composite of a host compound and metal oxide nanoparticles (“PγCyD-BaTiO ₃ ” in FIG. 2) having inclusion ability with respect to liquid crystal molecules (“NLC” in FIG. 2) in the liquid crystal layer. It is a conceptual diagram which shows the one aspect | mode of the liquid crystal display element containing the liquid crystal composition to contain. The present liquid crystal display element has a structure in which a liquid crystal layer is sandwiched between two substrates, at least one of which is transparent. The liquid crystal molecules control the alignment in the state A or the state B by applying electricity to the alignment film provided on the substrate and the electrode provided on the substrate. By providing a polarizing plate, a retardation film, etc., display is performed using these states A and B and an intermediate state between them. The liquid crystal display element can be applied to TN, STN, VA, IPS, and ECB, but TN is particularly preferable. The liquid crystal additive according to the present invention is dispersed in a liquid crystal layer interposed between a pair of substrates. The present invention is directed to converting the metal from a metal to a metal oxide, and the general formula (1-0) By including a liquid crystal compound represented by the formula, preferred dispersibility is exhibited.

  The distance (d) between the substrates of the present liquid crystal display element is preferably in the range of 2 to 5 μm, more preferably 3.5 μm or less. The product of the birefringence (Δn) of the liquid crystal composition and the distance (d) between the substrates is particularly preferably in the range of 0.3 to 0.4 μm, more preferably in the range of 0.30 to 0.35 μm, and 0.31. A range of ˜0.33 μm is particularly preferable. Display with favorable color reproducibility with high-speed response by setting the product of the distance (d) between the substrates of the liquid crystal display element and the product of the birefringence (Δn) of the liquid crystal composition and the distance (d) between the substrates. Can be obtained.

[Complex]
As shown in FIG. 1, the composite in the present invention is a host compound having an inclusion ability for liquid crystal molecules (“PγCyD” in FIG. 1) and at least one metal oxide nanoparticle (in FIG. 1, “BaTiO ₃ ”). The metal oxide nanoparticles and the host compound interact with each other by coordination bonds. In the present invention, the metal oxide nanoparticles are preferably protected from alteration due to external factors by the bond with the host compound. This is because a decrease in the dielectric constant can be prevented by suppressing the alteration of the metal oxide nanoparticles. In this invention, since the metal oxide nanoparticle which is excellent in stability compared with the conventional metal nanoparticle is used, it is thought that the fall of a dielectric constant can be prevented more.

  For the formation of the composite, the host compound may be 0.1 mol or more, preferably 0.1 to 50 mol, per 1 mol of the metal oxide nanoparticles. In the case where the host compound is a polymer, the amount used may be determined in terms of the number of moles per monomer unit.

  The content of the composite in the liquid crystal layer may be appropriately selected depending on the application, and is usually 0.1% by mass or less, preferably 0.08% by mass or less based on the guest liquid crystal.

[Metal oxide nanoparticles]
The average particle diameter of the metal oxide nanoparticles in the present invention is not particularly limited as long as it is a fine particle having a smaller particle diameter, but is preferably 50 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less. Although there is no lower limit, it is preferably 1 nm or more. In addition, the average particle diameter of a metal oxide nanoparticle can be measured with a transmission electron microscope.

  The metal species of the metal oxide nanoparticles are not particularly limited, and examples thereof include silicon, titanium, zirconia, and barium. Among these, silicon, titanium, and zirconia are preferable in terms of easy preparation. By selecting the metal species of the metal oxide nanoparticles from the above elements, it is possible to realize dispersibility with respect to liquid crystal and an improvement in dielectric constant in a wide frequency modulation range. In addition, these metal seed | species can be used individually or in combination of 2 or more types in the range which does not impair the objective of this invention. By combining two or more types, the frequency modulation range according to the application can be freely selected, and versatility can be improved.

[Host compound]
In the present invention, the host compound refers to a compound having an inclusion ability. In the present invention, the host compound may be appropriately selected according to the liquid crystal molecules of the guest liquid crystal, but preferably cyclodextrin, amylopectin, crown ether, cyclophane, calixarene, cucurbituril, isoguanine, cyclotriphosphazene, and these At least one selected from the group consisting of derivatives, more preferably cyclodextrin. Cyclodextrin is preferable in terms of excellent dispersibility in the host liquid crystal because it is excellent in solubility in water and other solvents. Examples of cyclodextrins include natural cyclodextrins such as α-, β-, and γ-cyclodextrins; branched cyclodextrins such as glucosyl and maltosyl. The cyclodextrin may be a monomer or a polymer.

  For the formation of an inclusion compound between a host compound and a liquid crystal molecule as a guest, it is important that the size and shape of the functional group of the liquid crystal molecule and the pore portion of the host compound are matched. This is because the guest liquid crystal molecules are included by the host compound, thereby increasing the free volume between the molecules of the liquid crystal composition and decreasing the viscosity of the liquid crystal. The decrease in the viscosity of the liquid crystal makes it possible to satisfactorily disperse the metal oxide nanoparticles protected by the host compound and to eliminate the delay in changing the orientation of the liquid crystal molecules. Since each of the host compounds has compatibility with a wide range of liquid crystal molecular species, the compatibility can be further improved by combining two or more kinds. Therefore, versatility can be improved by appropriately selecting the host compound from the above according to various liquid crystal molecules.

[Guest LCD]
The liquid crystal composition of the present invention includes a guest liquid crystal in addition to the composite. The guest liquid crystal is not limited to the existing liquid crystal, and any liquid crystal that can operate at room temperature may be used. For example, nematic liquid crystal, smectic liquid crystal, chiral nematic liquid crystal, and chiral smectic liquid crystal.

  The liquid crystal composition of the present invention contains a liquid crystal compound represented by the general formula (1-0) as a guest liquid crystal.

In formula (1-0), R is preferably an alkyl group having 2 to 4 carbon atoms, or an alkenyl group having 2 to 4 carbon atoms. A ₁ and A ₂ each independently represents a 1,4-phenylene group, a trans-1,4-cyclohexylene group or a naphthalene-2,6-diyl group. The 1,4-phenylene group or naphthalene-2,6-diyl group can be unsubstituted or have one or more F or Cl as substituents. Z ₁ and Z ₂ are each independently a single bond, —CF ₂ O—, or — (CH ₂ ) ₂ —. X ₁ and X ₂ are each independently F, CF ₃ or OCF ₃ . m represents 0, 1 or 2.

In the present invention, a liquid crystal composition containing at least one of the compounds represented by the following general formula (1-1) or (1-2) is more preferable. In general formulas (1-1) and (1-2), R, A ₁ , A ₂ , Z ₁ , Z ₂ , X ₁ , and X ₂ are the same as those in general formula (1-0).

In the liquid crystal composition of the present invention, the compound represented by the general formula (1-1) is preferably contained in an amount of 0 to 30 wt%. It is preferable to contain 5-70 wt% of compounds represented by general formula (1-2). The total amount of the compounds represented by the general formulas (1-1) and (1-2) is preferably 5 to 70 wt%. The total amount of the compounds represented by the general formula (1-0) is preferably 15 to 70 wt%. A compound where X ₁ is F or OCF ₃ exhibits a preferred dispersion of metal oxide nanoparticles.

[Composite Formation Method]
The composite can be formed by, for example, mixing a host compound and a metal oxide in a solvent, then pulverizing the solvent by sonication or microwave irradiation, and then removing the solvent. . Either the host compound or the metal oxide may be added to the solvent first, but it is preferable to add the metal oxide to the solvent in which the host compound as the protective agent is dispersed.

  Solvents used for forming the complex include water; alcohols such as methanol, ethanol and propanol; ethylene glycols such as monoethylene glycol, diethylene glycol and polyethylene glycol; ethers such as diethyl ether, tetrahydrofuran and diethylene glycol monomethyl ether At least one selected from the group consisting of;

  In the composite, the metal oxide nanoparticles constitute metal ions, and in order to obtain metal ions, a metal salt such as a metal halide may be used as a starting material.

  More specifically, for example, the complex can be formed by the following method. A host compound as a protective agent is dispersed in water and mixed with a metal oxide. Tetraethylene glycol is further added thereto, and then ultrasonic waves and microwaves are simultaneously irradiated in a nitrogen atmosphere. Thereafter, water and tetraethylene glycol in the solution are distilled off under reduced pressure, and vacuum drying is performed to obtain a composite. In addition, after replacing tetraethylene glycol in the solution after irradiation with ultrasonic waves and microwaves with ethanol, ethanol may be distilled off under reduced pressure and vacuum drying may be performed.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

(Synthesis Example 1) PγCyD-BaTiO ₃ nanoparticle composite In a 300 ml single-necked eggplant type flask containing a stirrer, 0.0171 g (0.014 mmol) of γ-cyclodextrin polymer (PγCyD) (manufactured by Junsei Chemical Co., Ltd.) Was added, and 15 ml of water was added thereto, followed by stirring for 1 hour using a magnetic stirrer. Then, 0.0301 g (0.14 mmol) of titanium tetraethoxide (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.0300 g (0.14 mmol) of diethoxybarium (manufactured by Wako Pure Chemical Industries, Ltd.) Stir for another 30 minutes. Next, 185 ml of tetraethylene glycol was added, and the ultraviolet / visible absorption spectrum was measured with an ultraviolet / visible spectrophotometer. After confirming the disappearance of the peak of the titanium ion, it was transferred to the reactor. Then, the air portion of the reactor was replaced with nitrogen to form a reducing atmosphere.

After sufficiently stirring with a magnetic stirrer, microwave (output: output: 30 minutes at 240 ° C. with a microwave / ultrasonic irradiation device (product name: microwave reactor, manufactured by Shikoku Keiki Kogyo Co., Ltd.) 1.5 kW) and ultrasonic waves (frequency: 20 kHz, irradiation intensity: 150 W) were simultaneously irradiated. Upon irradiation, the solution changed from colorless to blackish brown, and a complex (PγCyD-BaTiO ₃ nanoparticle complex) dispersion in which the γ-cyclodextrin polymer was bonded to the barium titanate nanoparticles was obtained. Using an ultrafilter (Ultrafiltration Membranes NMML5000, manufactured by Millipore), tetraethylene glycol was replaced with ethanol, and extra ions were ultrafiltered. Ethanol in this solution was distilled off under reduced pressure using a rotary evaporator, and vacuum drying was carried out overnight using a vacuum dryer to obtain a PγCyD-BaTiO ₃ nanoparticle composite.

The obtained PγCyD-BaTiO ₃ nanoparticle composite dispersion was dropped on a copper grid for a transmission electron microscope, dried, and analyzed by a transmission electron microscope. As a result, the average particle size of the PγCyD-BaTiO ₃ nanoparticle composite was It was 5.0 nm.

(Synthesis Example 2) PβCyD-TiO ₂ Nanoparticle Complex Into a 300 ml one-necked eggplant type flask containing a stirrer, β-cyclodextrin polymer (PβCyD) (manufactured by Junsei Chemical Co., Ltd.) 0.3746 g (0.33 mmol) The mixture was added with 15 ml of water, and stirred in an oil bath at 80 ° C. for 30 minutes using a magnetic stirrer. Thereafter, 0.0375 g (0.132 mmol) of titanium tetraisopropoxide (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further stirred in an oil bath at 80 ° C. for 30 minutes. Next, 185 ml of tetraethylene glycol was added, and the ultraviolet / visible absorption spectrum was measured with an ultraviolet / visible spectrophotometer. After confirming the peak of titanium ions, the reaction mixture was transferred to a reactor. Then, the air portion of the reactor was replaced with nitrogen to form a reducing atmosphere.

After sufficiently stirring with a magnetic stirrer, microwave (output: output: 30 minutes at 240 ° C. with a microwave / ultrasonic irradiation device (product name: microwave reactor, manufactured by Shikoku Keiki Kogyo Co., Ltd.) 1.5 kW) and ultrasonic waves (frequency: 20 kHz, irradiation intensity: 150 W) were simultaneously irradiated. Upon irradiation, the solution changed from colorless to black-brown, and a complex (PβCyD-TiO ₂ nanoparticle complex) dispersion in which β-cyclodextrin polymer was bound to titanium dioxide nanoparticles was obtained. Using an ultrafilter (Ultrafiltration Membranes NMML5000, manufactured by Millipore), tetraethylene glycol was replaced with ethanol, and excess ions were ultrafiltered. Ethanol in this solution was distilled off under reduced pressure using a rotary evaporator, and vacuum drying was carried out overnight using a vacuum dryer to obtain a PβCyD-TiO ₂ nanoparticle composite.

The obtained PβCyD-TiO ₂ nanoparticle composite dispersion was dropped on a copper grid for a transmission electron microscope, dried, and analyzed by a transmission electron microscope. As a result, the average particle size of the PβCyD-TiO ₂ nanoparticle composite was It was 16.0 nm.

(Synthesis Example 3) PβCyD-SiO ₂ nanoparticle composite In a 300 ml one-necked eggplant type flask containing a stirrer, β-cyclodextrin polymer (PβCyD) (manufactured by Junsei Chemical Co., Ltd.) 0.4540 g (0.4 mmol) Was added, and 15 ml of water was added thereto, followed by stirring for 1 hour using a magnetic stirrer. Thereafter, 0.6796 g (4.0 mmol) of silicon tetrachloride (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further stirred for 30 minutes. Next, 185 ml of tetraethylene glycol was added, and the ultraviolet / visible absorption spectrum was measured with an ultraviolet / visible spectrophotometer. After confirming the disappearance of the peak of silicon ions, the mixture was transferred to a reactor. Then, the air portion of the reactor was replaced with nitrogen to form a reducing atmosphere.

After sufficiently stirring with a magnetic stirrer, microwave (output: output: 30 minutes at 240 ° C. with a microwave / ultrasonic irradiation device (product name: microwave reactor, manufactured by Shikoku Keiki Kogyo Co., Ltd.) 1.5 kW) and ultrasonic waves (frequency: 20 kHz, irradiation intensity: 150 W) were simultaneously irradiated. Upon irradiation, the solution changed from colorless to black-brown, and a complex (PβCyD-SiO ₂ nanoparticle complex) dispersion in which β-cyclodextrin polymer was bonded to silicon dioxide nanoparticles was obtained. Using an ultrafilter (Ultrafiltration Membranes NMML5000, manufactured by Millipore), tetraethylene glycol was replaced with ethanol, and extra ions were ultrafiltered. Ethanol in this solution was distilled off under reduced pressure using a rotary evaporator, and vacuum drying was carried out overnight using a vacuum dryer to obtain a PβCyD-SiO ₂ nanoparticle composite.

The obtained PβCyD-SiO ₂ nanoparticle composite dispersion was dropped on a copper grid for a transmission electron microscope, dried, and analyzed by a transmission electron microscope. As a result, the average particle size of the PβCyD-SiO ₂ nanoparticle composite was It was 6.2 nm.

(Synthesis Example 4) βCyD-SiO ₂ nanoparticle composite In a 300 ml one-necked eggplant type flask containing a stirrer, β-cyclodextrin (βCyD) (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.4540 g (0.4 mmol) Was added, and 15 ml of water was added thereto, followed by stirring for 1 hour using a magnetic stirrer. Thereafter, 0.6786 g (4.0 mmol) of silicon tetrachloride (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further stirred for 30 minutes. Next, 185 ml of tetraethylene glycol was added, and the ultraviolet / visible absorption spectrum was measured with an ultraviolet / visible spectrophotometer. After confirming the disappearance of the peak of silicon ions, the mixture was transferred to a reactor. Then, the air portion of the reactor was replaced with nitrogen to form a reducing atmosphere.

After sufficiently stirring with a magnetic stirrer, microwave (output: output: 30 minutes at 240 ° C. with a microwave / ultrasonic irradiation device (product name: microwave reactor, manufactured by Shikoku Keiki Kogyo Co., Ltd.) 1.5 kW) and ultrasonic waves (frequency: 20 kHz, irradiation intensity: 150 W) were simultaneously irradiated. Upon irradiation, the solution changed from colorless to black-brown, and a complex (βCyD-SiO ₂ nanoparticle complex) dispersion in which β-cyclodextrin was bonded to silicon dioxide nanoparticles was obtained. Using an ultrafilter (Ultrafiltration Membranes NMML5000, manufactured by Millipore), tetraethylene glycol was replaced with ethanol, and extra ions were ultrafiltered. The solution was distilled off under reduced pressure with an ethanol rotary evaporator and dried in a vacuum dryer overnight to obtain a βCyD-SiO ₂ nanoparticle composite.

The obtained βCyD-SiO ₂ nanoparticle composite dispersion was dropped on a copper grid for a transmission electron microscope, dried, and analyzed by a transmission electron microscope. As a result, the average particle size of the βCyD-SiO ₂ nanoparticle composite was It was 8.4 nm.

(Synthesis Example 5) PγCyD-ZrO ₂ Nanoparticle Complex In a 300 ml single-necked eggplant type flask containing a stirrer, 0.0171 g (0.014 mmol) of γ-cyclodextrin polymer (PγCyD) (manufactured by Junsei Chemical Co., Ltd.) Was added thereto, and 15 ml of water was added thereto, followed by stirring for 30 minutes using a magnetic stirrer. Thereafter, 0.038 g (0.14 mmol) of zirconium tetraethoxide (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further stirred for 30 minutes. Next, 185 ml of tetraethylene glycol was added, and the ultraviolet / visible absorption spectrum was measured with an ultraviolet / visible spectrophotometer. After confirming the disappearance of the peak of zirconium ions, the mixture was transferred to the reactor. Then, the air portion of the reactor was replaced with nitrogen to form a reducing atmosphere.

After sufficiently stirring with a magnetic stirrer, microwave (output: output: 30 minutes at 240 ° C. with a microwave / ultrasonic irradiation device (product name: microwave reactor, manufactured by Shikoku Keiki Kogyo Co., Ltd.) 1.5 kW) and ultrasonic waves (frequency: 20 kHz, irradiation intensity: 150 W) were simultaneously irradiated. Upon irradiation, the solution changed from colorless to blackish brown, and a complex (PγCyD-ZrO ₂ nanoparticle complex) dispersion in which the γ-cyclodextrin polymer was bonded to the zirconium oxide particles was obtained. Using an ultrafilter (Ultrafiltration Membranes NMML5000, manufactured by Millipore), tetraethylene glycol was replaced with ethanol, and extra ions were ultrafiltered. Ethanol in this solution was distilled off under reduced pressure using a rotary evaporator, and vacuum drying was carried out overnight using a vacuum dryer to obtain a PγCyD-ZrO ₂ nanoparticle composite.

The obtained PγCyD-ZrO ₂ nanoparticle composite dispersion was dropped on a copper grid for a transmission electron microscope, dried, and analyzed by a transmission electron microscope. As a result, the average particle size of the PγCyD-ZrO ₂ nanoparticle composite was It was 7.2 nm.

Example 1
0.0013 g of PγCyD-ZrO ₂ nanoparticle composite described in Synthesis Example 5 was dissolved in 1 g of NTN-01 (manufactured by DIC Corporation) which is a guest liquid crystal. Next, after filtering using a syringe filter (Millex, manufactured by Millipore, pore size 0.45 μm), the liquid crystal cell was filled to prepare various liquid crystal display elements. Further, TN cells having a distance (d) between the substrates of 5 μm, 3 μm, and 2.5 μm were prepared. Liquid crystal display characteristics were measured using LCD-5200 manufactured by Otsuka Electronics Co., Ltd.

  The guest liquid crystal NTN-01 has physical properties of a transition temperature of 76 ° C., Δε of 3.5, and Δn of 0.125. Moreover, 7 wt% of compounds represented by general formula (1-1) and 16 wt% of compounds represented by general formula (1-2) are contained.

(Example 2)
The metal oxide nanoparticle composites described in Synthesis Examples 1 to 4 are dissolved in 1 g of guest liquid crystal NTN-01 (manufactured by DIC Corporation) by the method described in Example 1, and liquid crystal display elements such as various TN cells. The liquid crystal display characteristics were measured.

Example 3
The metal oxide nanoparticle composites described in Synthesis Examples 1 to 5 were dissolved in guest liquid crystal A1g by the method described in Example 1, liquid crystal display elements such as various TN cells were prepared, and the liquid crystal display characteristics were measured. As for the physical properties of the guest liquid crystal A, the transition temperature is 80 ° C., Δε is 4.6, and Δn is 0.122. Further, 0 wt% of the compound represented by the general formula (1-1), 10 wt% of the compound represented by the general formula (1-2), and a compound represented by m = 2 in the general formula (1-0) Contains 10 wt%.

Example 4
Table 1 shows the result of the response speed of the TN cell with d = 2.5 μm produced in Example 1 (in Table 1, “NTN-01 + nanoparticle”). For comparison, the result of not including the metal oxide nanoparticle composite (“NTN-01” in Table 1) is also shown. The response time was measured when the drive voltage was 5V and when it was 6V. The liquid crystal display element of the present invention improved the response time regardless of whether the measurement temperature was 0 ° C. or 25 ° C. The other TN cells produced in Examples 1 to 3 were evaluated in the same manner.

(Example 5)
The drive voltage of the TN cell with d = 2.5 μm, 3 μm, and 5 μm prepared in Example 1 was measured. The driving voltage of the TN cell of the present invention was reduced as compared with the TN cell not including the metal oxide nanoparticle composite. The d = 2.5 μm and 3 μm TN cells have better response speed and drive voltage than the d = 5 μm TN cells. In addition, it showed light transmittance with small wavelength dispersion, and showed characteristics useful for full-color display. The other TN cells produced in Examples 1 to 3 were evaluated in the same manner.

(Example 6)
When the liquid crystal layer to which the metal oxide nanoparticle composite prepared in Example 1 was added was visually compared with the liquid crystal layer to which the metal nanoparticle composite was added, the metal oxide nanoparticle composite was compared with the liquid crystal layer. Dispersibility was good. The other TN cells produced in Examples 1 to 3 were evaluated in the same manner.

Claims (6)

A complex in which a host compound having an inclusion ability for liquid crystal molecules is bonded to metal oxide nanoparticles, and a general formula (1-0)

(In the formula, R represents an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms; A ₁ and A ₂ are each independently a 1,4-phenylene group, trans-1,4; -Represents a cyclohexylene group or a naphthalene-2,6-diyl group, and the 1,4-phenylene group or naphthalene-2,6-diyl group is unsubstituted or substituted with one or more F or Cl Z ₁ and Z ₂ each independently represents a single bond, —COO—, —CF ₂ O—, or — (CH ₂ ) ₂ —; each of X ₁ and X ₂ independently represents H, F, Cl, CF ₃ or OCF ₃ ; m represents 0, 1 or 2)
The liquid crystal composition containing the compound represented by these.   2. The liquid crystal composition according to claim 1, wherein the host compound is at least one selected from the group consisting of cyclodextrin, amylopectin, crown ether, cyclophane, calixarene, cucurbituril, isoguanine, cyclotriphosphazene, and derivatives thereof.   The liquid crystal composition according to claim 1 or 2, wherein the metal oxide nanoparticles contain at least one selected from the group consisting of silicon dioxide, titanium oxide, zirconium oxide, barium titanate and barium zirconate.   A liquid crystal layer is sandwiched between two substrates, at least one of which is transparent, and the liquid crystal layer includes the liquid crystal composition according to any one of claims 1 to 3. Liquid crystal display element.   The liquid crystal display element according to claim 4, wherein the distance (d) between the substrates is in the range of 2 to 5 μm.   The liquid crystal display element according to claim 5, wherein a product of birefringence (Δn) of the liquid crystal composition and a distance (d) between the substrates is in a range of 0.3 to 0.4 μm.

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