JP2015105348A - Liquid crystal composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal composition into which nanoparticles can be dispersed stably over a long period of time, and a liquid crystal display element including the liquid crystal composition.SOLUTION: A liquid crystal composition comprises: a nanoparticle that has an average particle diameter of 10 to 100 nm and is surface-hydrophobized; and a chiral compound, and the content of the nanoparticle is 0.01 to 5.0 mass% 15 pts.mass. The liquid crystal composition has a pitch of 10 to 15 μm. A liquid crystal display element includes a structure in which a liquid crystal layer is sandwiched between two sheets of substrates, at least one of which is transparent, and the liquid crystal layer contains any one of the above-described liquid crystal composition.

Description

  The present invention relates to a liquid crystal composition containing a nanoparticle and a chiral compound and a liquid crystal display device.

  In general, liquid crystal electro-optic effect elements (LC-EO devices) have been put into practical use in various operation modes including TN (Twisted Nematic) type and STN (Super Twisted Nematic) type depending on the liquid crystal used. (See Non-Patent Document 1). Among them, 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. In particular, in recent years, a liquid crystal display (LCD) having a high contrast and a fast response has attracted attention as a next-generation display.

  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 also reported that the threshold voltage in the LC-EO device of nematic liquid crystal can be lowered by using a liquid crystal layer in which nanoparticles are mixed with liquid crystal molecules (see Non-Patent Document 2). .

JP 2005-148705 A

Mitsuharu Okano and Keisuke Kobayashi (co-author), "Liquid Crystal-Applied Edition", published by Baifukan Co., Ltd., 1985, pages 13-15 F. Haraguchi, et.al., Japanese Journal of Applied Physics, 2007, vol.46, p.L796-797. H. Hasebe and S. Kobayashi, SID International Symposium Digest of Technical Papers, 1985, vol. 21, p. 81-87.

  In order to sufficiently achieve high-speed response by adding nanoparticles, it is important that the nanoparticles are stably dispersed in the liquid crystal material for a long period of time. Therefore, an object of the present invention is to provide a liquid crystal composition in which nanoparticles can be stably dispersed for a long period of time, and a liquid crystal display device containing the liquid crystal composition.

  The inventors of the present invention have made extensive studies in order to solve the above problems. As a result, the liquid crystal composition contains both nanoparticles having a specific size and a hydrophobic compound, and a chiral compound. It was found that the long-term spatial dispersion stability in the liquid crystal composition was significantly improved, and the present invention was completed.

The present invention comprises nanoparticles having an average particle diameter of 10 to 100 nm and hydrophobized surface treatment, and a chiral compound, and the content of the nanoparticles is 0.01 to 5.0% by mass. A liquid crystal composition is provided.
The present invention also provides a liquid crystal display element containing the liquid crystal composition in a liquid crystal layer.

  In the liquid crystal composition according to the present invention, nanoparticles having a specific size can be stably dispersed in the liquid crystal for a long period of time. For this reason, the liquid crystal display element manufactured from the liquid crystal composition can reduce the operating voltage and the response time. That is, the liquid crystal composition according to the present invention is particularly suitable as a material for a liquid crystal device that requires high-speed response.

In Example 1, it is the photograph of the bottles 2-1 to 2-3 after leaving still for 2 weeks. In Example 2, it is the figure which showed the VT curve in 25 degreeC of each liquid crystal display element produced from liquid crystal composition AD. In Example 2, it is the figure which showed the VT curve in 0 degreeC of each liquid crystal display element produced from liquid crystal composition AD. In Example 2, it is the figure which showed the response time (tau) _off -operating voltage characteristic in 0 degreeC of each liquid crystal display element produced from liquid crystal composition AD. In Example 2, it is the figure which showed the response time (tau) _on -operating voltage characteristic in 0 degreeC of each liquid crystal display element produced from liquid crystal composition AD.

  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 composition]
The liquid crystal composition according to the present invention is characterized in that it has an average particle diameter of 10 to 100 nm, and contains hydrophobic-treated nanoparticles and a chiral compound. By containing nanoparticles having a specific size (the shape may be irregular) together with chiral particles, long-term stable dispersibility of the nanoparticles in the liquid crystal matrix can be obtained. That is, the chiral compound can significantly reduce or eliminate the precipitation and aggregation of the nanoparticles in the liquid crystal composition. For this reason, by using the liquid crystal composition according to the present invention, the operating voltage and response time of the LC-EO device can be reduced, and the contrast ratio can be improved. The liquid crystal composition according to the present invention is particularly useful for realizing a stable reduction in response time in an LC-EO device such as a liquid crystal display element at a low temperature of 0 ° C. or lower.

  The reason why the dispersibility of the nanoparticles in the liquid crystal matrix is stabilized for a long time by containing the chiral compound is that the chiral compound undergoes Brownian thermal oscillation in the liquid crystal matrix and collides with the nanoparticles, It is interpreted that the average spacing of nanoparticles in is kept constant. The same effect can be expected by adding a deformed molecule having no chirality instead of the chiral molecule.

On the other hand, the addition of the nanoparticles reduces the operating voltage and the response time of the LC-EO device. By adding such nanoparticles, the order parameter (S) of the liquid crystal molecules decreases by several percent. It has been shown experimentally. As a result, for example, the threshold voltage (V _th ) of the relationship (VT curve) between the light transmittance (T) of the electro-optic effect of the TN cell and the actual effect (V) of the applied AC voltage is expressed by the following equation (1): Given in.

Therefore, the effective elastic modulus (K _eff ) is approximately proportional to S ² . Further, since the dielectric anisotropy (Δε) is proportional to S, V _th is proportional to S ^1/2 , and as S decreases, V _th also decreases (see, for example, Non-Patent Document 3). From this relationship, the decrease rate of relative V _th ([δV _th ] / [V]) is expressed by the following formula (2).

That is, the decrease rate of relative _Vth is half of the decrease rate of S. Thus, it is understood that a decrease in S leads to a decrease in _Vth . It was also experimentally shown that a decrease in S corresponds to an increase in the temperature of the liquid crystal without addition of nanoparticles.

Regarding the response times τ _on and τ _off , the following equations (3) and (4) are obtained. Further, the relative change rate of τ _off is given by the following equation (5).

That is, if the thickness (d) of the liquid crystal layer is decreased, γ is decreased, and K _eff is increased, τ _off is shortened. The narrowing of d is realized by NTN (Narrow gap TN) or the like (see, for example, Non-Patent Document 3). Since γ ₁ = aS ² is approximated, as S decreases, γ ₁ also decreases. In order to shorten τ _off , K _eff needs to be increased. Furthermore, since the degree of order also depends on the applied voltage, the molecular theory that leads to an increase in K _eff has not been fully elucidated. However, according to NTN-LCD LCD MASTER (manufactured by SHINTTECH) computer simulation, K _eff , especially Increases in K ₂₂ and K ₃₃ are shown. In the examples described later, when NTN-LCD was used and the thickness (d) of the liquid crystal layer was 3 μm, the response time τ _off was reduced by about 40% ([δτ _off ] / [τ _off ] × 100≈− 40%). The cause was estimated to be a reduction of about 20% as the addition effect of the chiral compound and a reduction of about 20% as the addition effect of the nanoparticles. That is, [δγ ₁ ] / [γ ₁ ] and [δK _eff ] / [K _eff ] are estimated to be substantially equivalent. On the other hand, the response time τ _on is clearly reduced by the increase in the applied voltage, as is clear from the above equation (3), and has been experimentally realized. This effect is called an Over voltage driving effect.

  In the present invention, the liquid crystal composition contains nanoparticles whose surface has been subjected to hydrophobic treatment. If the average particle size is within a specific range (10 to 100 nm), the surface is hydrophilic. Even in the case where nanoparticles are contained, a liquid crystal composition having a long-term dispersion stability improved similarly by the chiral compound.

[Nanoparticles with hydrophobized surface treatment]
The nanoparticles contained in the liquid crystal composition according to the present invention have a hydrophobic surface and an average particle diameter of 10 to 100 nm. The size of the nanoparticles is preferably an average particle size of 10 to 50 nm, more preferably 10 to 40 nm, and even more preferably 20 to 40 nm. By using nanoparticles whose average particle diameter is in the above range and whose surface is hydrophobic in the liquid crystal composition, it becomes possible to achieve a sufficiently high-speed response of the liquid crystal display device produced by the liquid crystal composition, The operating voltage (applied voltage) and response time can be sufficiently reduced.

  The nanoparticle is preferably a particle containing one or a plurality of nuclei, more preferably a particle in which one or a plurality of inorganic nuclei are included in a hydrophobic substance. If the average particle diameter of the nanoparticles is in the range of 10 to 100 nm, the number of nuclei contained in each nanoparticle is not particularly limited, and the size of the nuclei and the type of hydrophobic substance covering the surface It can be appropriately prepared in consideration of the size and the like. As the nanoparticles used in the present invention, the surface of the hydrophobizing agent obtained by treating nanoparticles made of an inorganic substance having an average primary particle size of 7 to 40 nm with a hydrophobizing agent (hydrophobic organic compound). Preferably, the particles are covered with irregular shapes and contain about 7 to 10 nuclei (nanoparticles having an average primary particle diameter of 7 to 40 nm made of an inorganic substance) per particle. In addition, the nanoparticle in which one or a plurality of nanoparticles are contained in the organic molecule as described above is also referred to as a “nanoparticle system”.

As this nanoparticle, the particle | grains from which a nucleus is comprised from an oxide, a semiconductor, or these composites are preferable. Examples of the oxide include silicon dioxide (SiO ₂ , silica), titanium oxide (TiO ₂ , titania), aluminum oxide (Al ₂ O ₃ , alumina), zirconium oxide (ZrO ₂ , zirconia), zinc oxide (ZnO), Examples thereof include barium titanate (BaTiO ₃ ) and barium zirconate (BaZrO ₃ ). Examples of the semiconductor include cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium selenide (CdSe), zinc sulfide (ZnS), copper telluride (CuTe), and the like. Among these, silica, titania and alumina are preferable in terms of easy preparation. By selecting nanoparticles whose nuclei are composed of the above compounds, it is possible to achieve dispersibility with respect to liquid crystals and an improvement in dielectric constant in a wide frequency modulation range. In addition, the particle | grains used as the nucleus of this nanoparticle 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.

  Hydrophobization surface treatment is performed by modifying hydrophobic functional groups by various chemical reactions to reactive groups such as hydroxyl groups on the surface of the nanoparticles. Hydrophobization with a hydrophobic functional group includes, for example, alkylsilylation, dialkylsilylation, trialkylsilylation, dialkylsiloxaneation, dialkylpolysiloxaneation, aminoalkylsilylation, alkylsilylation, methacrylsilylation, alkyl , Dialkylation, trialkylation and the like.

  As the hydrophobizing agent, a silane coupling agent, silicone oil, silazane or the like is used. The hydrophobizing agents can be used alone or in combination. The method of hydrophobizing treatment is performed, for example, by placing fine powder in a container equipped with a stirring device, stirring in a nitrogen atmosphere, and using the hydrophobizing agent alone or the hydrophobizing agent and the charge adjusting agent as necessary. It can be carried out by a dry treatment method in which it is dropped or sprayed together with a solvent, or a hydrophobizing agent is vaporized by heating and sufficiently dispersed with fine powder, followed by heating and then cooling.

  The average particle diameter of the nanoparticles used in the present invention can be measured, for example, with a transmission electron microscope. Specifically, the particle diameter of each particle was the area equivalent circle diameter calculated for each particle from the transmission electron micrograph, and the average particle diameter of 200 particles was the average particle diameter of the nanoparticles.

Nanoparticles used in the present invention are those in which fumed oxide nanoparticles produced by combustion hydrolysis of halides such as silicon halide, titanium halide, and aluminum halide are surface-treated with a hydrophobizing agent. preferable. Among the nanoparticles obtained by hydrophobizing surface treatment of fumed oxide nanoparticles, for example, “AEROSIL (registered trademark)” is used as the hydrophobized surface treatment particle of fumed silica, and as the hydrophobized surface treatment particles of fumed titania, “ “AEROXIDE (registered trademark) TiO ₂ ” can be used as the hydrophobized surface-treated particles of fumed zirconia, for example, “AEROXIDE (registered trademark) ALu” (both manufactured by EVONIK).

  Content of the said nanoparticle in the liquid-crystal composition which concerns on this invention is 0.01-5.0 mass%. In the liquid crystal composition according to the present invention, the content of the nanoparticles is preferably 0.01 to 2.0 mass%, more preferably 0.1 to 2.0 mass%, and 0.1 to 1.2 mass%. % Is more preferable, and 0.1 to 1.0% by mass is even more preferable. When the content of the nanoparticles is within the above range, the effect of addition by the nanoparticles can be sufficiently exhibited. In addition, the liquid crystal composition according to the present invention may contain only one type of nanoparticle or a combination of two or more types.

[Chiral compounds]
The chiral compound contained in the liquid crystal composition according to the present invention may be any of a compound having an asymmetric atom, a compound having axial asymmetry, a compound having plane asymmetry, and an atropisomer, and the chiral compound is polymerizable. It may have a group or may not have a polymerizable group.
In a compound having an asymmetric atom, it is preferable that the asymmetric atom is an asymmetric carbon atom because steric inversion hardly occurs. However, a hetero atom may be an asymmetric atom. The asymmetric atom may be introduced into a part of the chain structure or may be introduced into a part of the cyclic structure.
As the chiral compound used in the present invention, a compound having an asymmetric atom is preferable, and a compound having an asymmetric carbon atom is more preferable.

  The compound in which the liquid crystal composition has an asymmetric atom is preferably an optically active compound represented by the following general formula (IV).

In general formula (IV), R ¹ and R ² each independently represent a linear or branched alkyl group having 1 to 30 carbon atoms, a hydrogen atom, a fluorine atom, or a cyano group. One or more non-adjacent CH ₂ groups of the alkyl group are —O—, —S—, —NH—, —N (CH ₃ ) —, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —S—CO—, —CO—S—, —O—SO ₂ —, —SO ₂ —O—, —CH═CH—, —C≡C. -, A cyclopropylene group, or -Si (CH ₃ ) _2- may be substituted, and one or more hydrogen atoms of the alkyl group may be a fluorine atom, a chlorine atom, a bromine atom or a cyano (CN) group. Or may have a polymerizable group. In addition, the alkyl group may contain a fused or spirocyclic system and contain one or more aromatic or aliphatic rings that may contain one or more heteroatoms. But you can. The ring may be optionally substituted with an alkyl group, an alkoxy group, or a halogen. In the compound represented by the general formula (IV), R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 30 carbon atoms, —O—R ^4b , —CO—. O—R ^4b or a cyano group is preferable. ^{-O-R 4b,} or ^{-CO-O-R 4b} in ^{R 4b} each independently represents a linear or branched alkyl group having a carbon number of 1 to 29.

In the general formula (IV), each Z is independently —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— or —CO—N. (R ^4a ) —, —N (R ^4a ) —CO—, —OCH ₂ —, —CH ₂ O—, —SCH ₂ —, —CH ₂ S—, —CF ₂ O—, —OCF ₂ —, — _{CF 2 S -, - SCF 2} -, - CH 2 CH 2 -, - CF 2 CH 2 -, - CH 2 CF 2 -, - CF 2 CF 2 -, - CH = CH -, - CF = CH-, -CH = CF-, -CF = CF-, -C≡C-, -CH = CH-CO-O-, -O-CO-CH = CH-, -N = N- or a single bond. -CO-N ^{(R 4a)} -, or ^-N (R 4a) is ^{R 4a} in -CO- each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms . In the compound represented by the general formula (IV), each Z is preferably independently —CO—O—, —O—CO—, —C≡C—, or a single bond.

In general formula (IV), A ¹ and A ² are each independently a phenylene group, cyclohexylene group, dioxolandiyl group, cyclohexenylene group, bicyclo [2.2.2] octylene group, piperidinediyl group, naphthalene. It represents a cyclic group selected from a diyl group, a decahydronaphthalenediyl group, a tetrahydronaphthalenediyl group, or an indanediyl group. In the phenylene group, naphthalenediyl group, tetrahydronaphthalenediyl group, or indanediyl group, one or more of —CH═ in the ring may be replaced with a nitrogen atom. The cyclohexylene group, dioxolanediyl group, cyclohexenylene group, bicyclo [2.2.2] octylene group, piperidinediyl group, decahydronaphthalenediyl group, tetrahydronaphthalenediyl group, or indanediyl group is one in the ring. Or two non-adjacent —CH ₂ — may be replaced by —O— and / or —S—. Furthermore, one or more hydrogen atoms of the cyclic group may be replaced with a fluorine atom, a chlorine atom, a bromine atom, a cyano group, or a nitro (NO ₂ ) group. The alkyl group having 1 to 7 carbon atoms which may be replaced with a fluorine atom or a chlorine atom, and one or more hydrogen atoms wherein one or more hydrogen atoms may be replaced with a fluorine atom or a chlorine atom 1 to 7 alkoxy groups, one or two or more hydrogen atoms may be replaced by fluorine atoms or chlorine atoms, an alkylcarbonyl group having 1 to 7 carbon atoms, or one or two or more hydrogen atoms are fluorine It may be replaced with an alkoxycarbonyl group having 1 to 7 carbon atoms which may be replaced with an atom or a chlorine atom. In the compound represented by the general formula (IV), A ¹ and A ² are preferably each independently a phenylene group or a cyclohexylene group.

  In general formula (IV), m is 1, 2, 3, 4 or 5. As the compound represented by the general formula (IV), m is preferably 1 or 2.

However, in general formula (IV), either one or both of R ¹ and R ² are groups having an asymmetric atom. The compound represented by the general formula (IV) is also preferably a dichiral compound in which both R ¹ and R ² are chiral groups having an asymmetric atom. Specific examples of the dichiral compound include compounds represented by any one of the following general formulas (IV-a1) to (IV-a11). The partial structural formulas in the following general formulas (IV-a1) to (IV-a11), -A ^1- (ZA ² ) _m- , are the same as those in the general formula (IV).

In the general formulas (IV-a1) to (IV-a11), each R ³ independently represents a linear or branched alkyl group having 1 to 10 carbon atoms, and one of the alkyl groups or When two or more non-adjacent CH ₂ groups are —O—, —S—, —NH—, —N (CH ₃ ) —, —CO—, —CO—O—, —O—CO—, —O; -CO-O -, - S- CO -, - CO-S -, - O-SO 2 -, - SO 2 -O -, - CH = CH -, - C≡C-, cyclopropylene group or -Si (CH ₃ ) ₂ — may be replaced, and one or more hydrogen atoms of the alkyl group may be replaced by a fluorine atom, a chlorine atom, a bromine atom or a cyano group, and have a polymerizable group. Also good. Examples of the polymerizable group include a vinyl group, an allyl group, and a (meth) acryloyl group. In the compounds represented by the general formulas (IV-a1) to (IV-a11), R ³ is a straight chain having 4 to 8 carbon atoms such as C ₄ H _9, C ₆ H ₁₃ , C ₈ H ₁₇ and the like. Or it is preferable that it is a branched alkyl group.

In the general formulas (IV-a1) to (IV-a11), X ³ and X ⁴ are each a halogen atom (F, Cl, Br, I), a cyano group, a phenyl group (one or more of the phenyl groups) Any hydrogen atom of is optionally substituted with a halogen atom (F, Cl, Br, I), a methyl group, a methoxy group, —CF ₃ , or —OCF ₃ ), a methyl group, a methoxy group, or —CF _3. Or —OCF ₃ . As the compounds represented by the general formulas (IV-a1) to (IV-a11), X ³ is preferably a methyl group. However, in general formulas (IV-a3) and (IV-a8), in order for the position marked with * to be an asymmetric atom, a group different from X ³ is selected for X ⁴ .

In the general formula (IV-a1) ~ (IV -a11), n 3 is an integer of 0 to 20.

R ⁵ in the general formulas (IV-a4) and (IV-a9) is a hydrogen atom or a methyl group.
Examples of Q in the general formulas (IV-a5) and (IV-a10) include divalent hydrocarbon groups such as a methylene group, an isopropylidene group, and a cyclohexylidene group.
K in general formula (IV-a11) is an integer of 0-5.

As the compounds represented by the general formulas (IV-a1) to (IV-a11), compounds in which R ³ is a linear or branched alkyl group having 4 to 8 carbon atoms are preferable. Above all, the general formula (IV-a1) ~ (IV -a3), (IV-a6) ~ (IV-a8), examples of the compound represented by (IV-a11), ^{R 3} is a 4 to 8 carbon atoms A compound that is a linear or branched alkyl group and X ³ is a methyl group is preferred.

As the partial structural formulas in the general formulas (IV) and (IV-a1) to (IV-a11), -A ^1- (ZA ² ) _m- , the structural formula represented by the following general formula (IV-b) It is preferable that In general formula (IV-b), the definition of Z is the same as in general formula (IV).

In general formula (IV-b), rings A, B, and C are each independently a phenylene group, a cyclohexylene group, or a naphthalenediyl group, and in these groups, any one or two or more of a benzene ring The hydrogen atom may be substituted with a halogen atom (F, Cl, Br, I), a methyl group, a methoxy group, —CF ₃ , —OCF ₃ , and any one or more carbons of the benzene ring The atom may be substituted with a nitrogen atom.

As the compound represented by the general formula (IV-b), a compound represented by any one of the following general formulas (IV-b1) to (IV-b6) is more preferable. However, in these formulas, any one or more hydrogen atoms of the benzene ring are substituted with a halogen atom (F, Cl, Br, I), a methyl group, a methoxy group, —CF ₃ , or —OCF _3. And any one or more carbon atoms of the benzene ring may be substituted with a nitrogen atom. The definition of Z is the same as in formula (IV).

  As the ring of the compound represented by the general formula (IV), in terms of reliability, a benzene ring or a cyclohexane ring is preferable to a heterocyclic ring such as a pyridine ring or a pyrimidine ring. In terms of increasing the dielectric anisotropy, it is preferable to use a compound having a heterocyclic ring such as a pyridine ring or a pyrimidine ring. In that case, the polarizability of the compound is relatively large. On the other hand, in the case of a compound having a hydrocarbon ring such as a benzene ring or a cyclohexane ring, the polarizability of the compound is low. For this reason, it is preferable to select an appropriate content according to the polarizability of the chiral compound.

As the chiral compound used in the present invention, among the compounds represented by the general formula (IV), R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 30 carbon atoms. , —O—R ^4b , —CO—O—R ^4b , or a cyano group (R ^4b independently represents a linear or branched alkyl group having 1 to 29 carbon atoms). , Z each independently represents —CO—O—, —O—CO—, —C≡C—, or a single bond, and A ¹ and A ² each independently represents a phenylene group or a cyclohexylene group. And a compound in which m is 1 or 2 (wherein either R ¹ or R ² has an asymmetric carbon atom) is preferred, and chiral molecules (C-1) and (C-2) in the examples described later ) Or (C-4) is more preferable, and a chiral molecule C-1) or (C-4) are more preferred, the chiral molecules (C-4) are particularly preferred.

  In addition, as the chiral compound used in the liquid crystal composition according to the present invention, a compound having axial asymmetry or an atropisomer can also be used.

Axis asymmetry means that the substituents X ^a and Y ^a are different from each other at one end of the shaft in a compound in which rotation of the bond axis is hindered, such as the allene derivatives shown below and the biphenyl derivatives shown below. also express at different substituents X ^b and Y ^b are each other at the other end side. A case where rotation of the bond axis is hindered by the influence of steric hindrance such as a biphenyl derivative is called atropisomerism.

  Examples of the compound having axial asymmetry used in the liquid crystal composition according to the present invention include compounds represented by the following general formula (IV-c1) or (IV-c2).

In general formula (IV-c2), at least one of X ⁶¹ and Y ⁶¹ , X ⁶² and Y ⁶² is present, and X ⁶¹ , X ⁶² , Y ⁶¹ , and Y ⁶² are each independently − It represents any of CH ₂ —, —CO—, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, boron atom, or silicon atom. In the case of a nitrogen atom, a phosphorus atom, a boron atom, or a silicon atom, it may be bonded to a substituent such as an alkyl group, an alkoxy group, or an acyl group so as to satisfy a required valence.

In the general formula (IV-c2), E ⁶¹ and E ⁶² are each independently a hydrogen atom, alkyl group, aryl group, allyl group, benzyl group, alkenyl group, alkynyl group, alkyl ether group, alkyl ester group, alkyl group. It represents either a ketone group, a heterocyclic group or a derivative thereof.

In Formula (IV-c1), R ⁶¹ and R ⁶² each independently represent a phenyl group, a cyclopentyl group, or a cyclohexyl group that may be substituted with an alkyl group, an alkoxyl group, or a halogen atom, and R ⁶³ , R ⁶⁴ , R ⁶⁵ , R ⁶⁶ , R ⁶⁷ and R ⁶⁸ each independently represent a hydrogen atom, an alkyl group, an alkoxyl group, an acyloxy group, a halogen atom, a haloalkyl group, or a dialkylamino group. However, it excludes when both ^R65 and ^R66 are hydrogen atoms.

In the formula (IV-c1), two of R ⁶³ , R ⁶⁴ and R ⁶⁵ may form a methylene chain which may have a substituent, or may have a substituent. A mono- or polymethylenedioxy group may be formed. Similarly, two of R ⁶⁶ , R ⁶⁷ and R ⁶⁸ may form a methylene chain which may have a substituent, and may have a substituent, mono or polymethylene A dioxy group may be formed.

In addition, as the chiral compound used in the liquid crystal composition according to the present invention, a compound having surface asymmetry can also be used.
Examples of the compound having surface asymmetry include a helicene derivative represented by the following general formula (IV-c3). In such a helicene derivative, the front-rear relationship of the overlapping rings cannot be freely converted, so that the case where the ring takes a right-handed spiral structure is distinguished from the case where it takes a left-handed spiral structure, and chirality is determined. To express.

In general formula (IV-c3), at least one of X ⁶¹ and Y ⁶¹ , X ⁶² and Y ⁶² is present, and X ⁶¹ , X ⁶² , Y ⁶¹ , and Y ⁶² are each independently- CH ₂ -, - CO-,
An oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, a boron atom, or a silicon atom is represented. In the case of a nitrogen atom, a phosphorus atom, a boron atom, or a silicon atom, it may be bonded to a substituent such as an alkyl group, an alkoxy group, or an acyl group so as to satisfy a required valence.

In general formula (IV-c3), E ⁶¹ and E ⁶² each independently represent a hydrogen atom, an alkyl group, an aryl group, an allyl group, a benzyl group, an alkenyl group, an alkynyl group, an alkyl ether group, an alkyl ester group, an alkyl group. It represents either a ketone group, a heterocyclic group or a derivative thereof.

  The chiral compound contained in the liquid crystal composition is preferably a compound having a large helical twisting power so that the helical structure pitch is small. In particular, when adjusting DHFLC having a short helical pitch of 400 nm or less, it is preferable to use a compound having a large helical induction force. A compound having a large helical induction force can reduce the amount of addition necessary for obtaining a desired pitch, so that a chiral compound having a high raw material cost can be minimized, and is preferable from the viewpoint of cost reduction. From this point of view, preferred chiral compounds are compounds represented by any one of the following general formulas (IV-d1) to (IV-d3), which are compounds having an asymmetric atom, and compounds having axial asymmetry. Examples include compounds represented by any one of general formulas (IV-d4) to (IV-d5).

In the general formulas (IV-d1) to (IV-d5), R ⁷¹ and R ⁷² are each independently a hydrogen atom, a halogen atom, a cyano (CN) group, an isocyanate (NCO) group, an isothiocyanate (NCS). ) Group or an alkyl group having 1 to 20 carbon atoms. Any one or two or more —CH ₂ — in the alkyl group is an oxygen atom, a sulfur atom, —COO—, —OCO—, —CH═CH—, —CF═CF—, or —C≡. It may be replaced with C-, and any hydrogen atom in the alkyl may be replaced with a halogen atom.

In the general formulas (IV-d1) to (IV-d5), A ⁷¹ and A ⁷² are each independently an aromatic or non-aromatic 3- to 8-membered ring or a condensed group having 9 or more carbon atoms. Represents a ring, and any one or more hydrogen atoms of these rings may be replaced by halogen, an alkyl group having 1 to 3 carbon atoms or a haloalkyl group, and one or more of the rings —CH ₂ — may be replaced with an oxygen atom, a sulfur atom, or —NH—, and one or more —CH═ in the ring may be replaced with —N═.

In the general formula (IV-d1) ~ (IV -d5), Z 71 and ^{Z 72} are each independently a single bond or represents an alkylene group having 1 to 8 carbon atoms, arbitrary -CH ₂ -, Oxygen atom, sulfur atom, -COO-, -OCO-, -CSO-, -OCS-, -N = N-, -CH = N-, -N = CH-, -N (O) = N-,- N = N (O) —, —CH═CH—, —CF═CF—, or —C≡C— may be substituted, and any hydrogen atom may be substituted with a halogen atom.

In the general formulas (IV-d1) to (IV-d5), X ⁷¹ and X ⁷² are each independently a single bond, —COO—, —OCO—, —CH ₂ O—, —OCH ₂ —, —CF _2. O -, - OCF ₂ -, or _-CH 2 CH ₂ - represents a.

In the general formulas (IV-d1) to (IV-d5), m ₇₁ and m ₇₂ each independently represent an integer of 1 to 4. However, either one of m ₇₁ and m ₇₂ in Formula (IV-d5) may be 0.

In the general formula (IV-d2), Ar ⁷¹ and Ar ⁷² each independently represent a phenyl group or a naphthyl group. In these groups, any one or two or more hydrogen atoms in the benzene ring may be substituted with a halogen atom, a methyl group, a methoxy group, —CF ₃ , or —OCF ₃ .

  In the liquid crystal composition according to the present invention, a chiral compound having a mesogen can also be used. Examples of such chiral compounds include compounds represented by general formulas (IV-e1) to (IV-e3).

In the general formulas (IV-e1) to (IV-e3), R ⁸¹ , R ⁸² , R ⁸³ and Y ⁸¹ are each independently a linear or branched alkyl group having 1 to 30 carbon atoms, Represents a hydrogen atom or a fluorine atom, and one or more non-adjacent CH ₂ groups of the alkyl group are —O—, —S—, —NH—, —N (CH ₃ ) —, —CO—. , -CO-O -, - O -CO -, - O-CO-O -, - S-CO -, - CO-S -, - O-SO 2 -, - SO 2 -O -, - CH = CH—, —C≡C—, a cyclopropylene group, or —Si (CH ₃ ) ₂ — may be substituted, and one or more hydrogen atoms of the alkyl group may be a fluorine atom, a chlorine atom, a bromine atom. It may be replaced with an atom or a cyano group and may have a polymerizable group. The alkyl group may include a fused or spirocyclic system, and may include one or more aromatic or aliphatic rings that may include one or more heteroatoms. . When the alkyl group includes a ring, one or more hydrogen atoms in the ring may be optionally substituted with an alkyl group, an alkoxy group, or a halogen.

In the general formulas (IV-e1) to (IV-e3), Z ⁸¹ , Z ⁸² , Z ⁸³ , Z ⁸⁴ and Z ⁸⁵ each independently represent an alkylene group having 1 to 40 carbon atoms. One or more CH ₂ groups of the alkyl group are —O—, —S—, —NH—, —N (CH ₃ ) —, —CO—, —COO—, —OCO—, —OCOO. Replaced by —, —S—CO—, —CO—S—, —CH═CH—, —CH═CF—, —CF═CH—, —CF═CF—, —CF ₂ — or —C≡C—. It may be done.

In the general formulas (IV-e1) to (IV-e3), X ⁸¹ , X ⁸² and X ⁸³ are each independently —O—, —S—, —CO—, —COO—, —OCO—, — _{OCOO -, - CO-NH -} , - NH-CO -, - CH 2 CH 2 -, - OCH 2 -, - CH 2 O -, - SCH 2 -, - CH 2 S -, - CF = CF-, —CH═CH—, —OCO—CH═CH—, —C≡C—, or a single bond is represented.

In the general formulas (IV-e1) to (IV-e3), A ⁸¹ , A ⁸² and A ⁸³ each independently represent a phenylene group, a cyclohexylene group, a dioxolandiyl group, a cyclohexenylene group or a bicyclo [2.2. 2] A cyclic group selected from an octylene group, a piperidinediyl group, a naphthalenediyl group, a decahydronaphthalenediyl group, a tetrahydronaphthalenediyl group, or an indanediyl group. In the phenylene group, naphthalenediyl group, tetrahydronaphthalenediyl group, or indanediyl group, one or more of —CH═ in the ring may be replaced with a nitrogen atom. The cyclohexylene group, dioxolanediyl group, cyclohexenylene group, bicyclo [2.2.2] octylene group, piperidinediyl group, decahydronaphthalenediyl group, tetrahydronaphthalenediyl group, or indanediyl group is one in the ring. Or two non-adjacent —CH ₂ — may be replaced by —O— and / or —S—. In addition, one or more hydrogen atoms of these cyclic groups may be replaced with a fluorine atom, a chlorine atom, a bromine atom, a cyano group, or a nitro group, and one or more hydrogen atoms. An alkyl group having 1 to 7 carbon atoms in which an atom may be replaced with a fluorine atom or a chlorine atom; 1 to 2 carbon atoms in which one or more hydrogen atoms may be replaced with a fluorine atom or a chlorine atom; An alkoxy group having 7, an alkylcarbonyl group having 1 to 7 carbon atoms in which one or two or more hydrogen atoms may be replaced by a fluorine atom or a chlorine atom, or one or two or more hydrogen atoms are It may be replaced with an alkoxycarbonyl group having 1 to 7 carbon atoms which may be replaced with a fluorine atom or a chlorine atom.

In the general formulas (IV-e1) to (IV-e3), m ₈₁ , m ₈₂ and m ₈₃ are each independently 0 or 1, and m ₈₁ + m ₈₂ + m ₈₃ is 1, 2 or 3.

In the general formulas (IV-e1) to (IV-e2), CH ^{* 81} and CH ^{* 82} each independently represent a chiral divalent group. Here, the chiral divalent group used for CH ^{* 81} and CH ^{* 82} is the following divalent group having an asymmetric atom.

And the following divalent groups with axial asymmetry

Is preferred. However, in these divalent groups used for CH ^{* 81} and CH ^{* 82} , any one or two or more hydrogen atoms of the benzene ring are a halogen atom (F, Cl, Br, I), a methyl group, It may be substituted with a methoxy group, —CF ₃ , —OCF ₃ , and any one or more carbon atoms of the benzene ring may be substituted with a nitrogen atom.

  More preferably, a compound represented by the following general formula, having an isosorbide skeleton as a chiral divalent group.

In the formula, R ⁹¹ and R ⁹² each independently represent a linear or branched alkyl group having 1 to 30 carbon atoms, a hydrogen atom, or a fluorine atom. One or more non-adjacent CH ₂ groups of the alkyl group are —O—, —S—, —NH—, —N (CH ₃ ) —, —CO—, —CO—O—, — O—CO—, —O—CO—O—, —S—CO—, —CO—S—, —O—SO ₂ —, —SO ₂ —O—, —CH═CH—, —C≡C—. , A cyclopropylene group or —Si (CH ₃ ) ₂ —, and one or more hydrogen atoms of the alkyl group may be replaced with a fluorine atom, a chlorine atom, a bromine atom or a CN group. Or may have a polymerizable group. The alkyl group may also contain a fused or spirocyclic system and contain one or more aromatic or aliphatic rings that can contain one or more heteroatoms. But you can. Any one or two or more hydrogen atoms in the ring may be optionally substituted with an alkyl group, an alkoxy group or a halogen.

In the formula, Z ⁹¹ and Z ⁹² are each independently —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CO—N ( R ^9a ) —, —N (R ^9a ) —CO—, —OCH ₂ —, —CH ₂ O—, —SCH ₂ —, —CH ₂ S—, —CF ₂ O—, —OCF ₂ —, —CF ₂ S—, —SCF ₂ —, —CH ₂ CH ₂ —, —CF ₂ CH ₂ —, —CH ₂ CF ₂ —, —CF ₂ CF ₂ —, —CH═CH—, —CF═CH—, — It represents CH═CF—, —CF═CF—, —C≡C—, —CH═CH—CO—O—, —O—CO—CH═CH— or a single bond. -CO-N ^{(R 9a)} - or ^{-N (R 9a)} R 9a in -CO- represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms.

In the general formula (IV-e3), CH ^{* 83} represents a chiral trivalent group. As the chiral trivalent group used for CH ^{* 83} , —X ⁸³ (Z ⁸³ A ⁸³ ) m ₈₃ R ⁸³ is located at any position of the chiral divalent group used for CH ^{* 81} and CH ^{* 82.} What is necessary is just to become a trivalent group by being able to couple | bond.

  The pitch in the liquid crystal composition (the length corresponding to one period in the helical structure of the liquid crystal molecules) is affected by the concentration of the chiral compound. As the amount (% by mass) of the chiral compound added to the liquid crystal composition increases, the pitch (μm) decreases. It is known that the relationship that the product of the addition amount of the chiral compound and the pitch is constant particularly holds well when the addition amount of the chiral compound is a low concentration of about 1 to several mass%, and the spiral having the reciprocal of this is known. The induced force (HTP) (1 / μm) is used as an evaluation parameter for the force that induces the torsional orientation inherent in the optically active compound. In the following mathematical formula, “P” is pitch (μm), and “C” is the amount of chiral compound added (% by mass).

  The content of the chiral compound in the liquid crystal composition according to the present invention is appropriately determined in consideration of the helical induction force of the chiral compound, the type and composition of the liquid crystal matrix, and the like so that the pitch in the liquid crystal composition is within a desired range. Can be determined. The chiral compound content in the liquid crystal composition according to the present invention is preferably such that the pitch in the liquid crystal composition is 100 μm or less, more preferably 70 μm or less, and 60 μm or less. The amount is more preferably, more preferably 5 to 30 μm, and particularly preferably 10 to 15 μm. By adding a chiral compound so that the pitch of the liquid crystal composition falls within the above range, the dispersion stability of the nanoparticles in the liquid crystal composition can be further increased.

  The liquid crystal composition according to the present invention includes TN (Twisted Nematic), STN (Super Twisted Nematic), ECB (Electrically Controlled Birefringence), VA (Vertically Aligned Nematic), IPS (In Plane Switching), FFS (Fringe Field Switching), It can be used as an operation mode of π cell, OCB (Optically Compensated Birefringence), SSFLC (Surface Stabilized Ferroelectric Liquid Crystal), Polymer-Stabilized V-FLCD, cholesteric liquid crystal, and the like. When the liquid crystal composition according to the present invention is other than TN and STN, the chirality due to the R-type chiral compound and the chirality due to the L-type chiral compound are offset between the R-type chiral compound and the L-type chiral compound. That is, the entire liquid crystal composition is contained so that chirality is canceled.

  In general, a liquid crystal composition to which nanoparticles are added may be difficult to inject into a liquid crystal cell having a narrow interval, but the liquid crystal composition according to the present invention includes a chiral compound in addition to nanoparticles. Therefore, there is an advantage that the liquid crystal cell having a narrow interval of about 2.5 to 3 μm can be smoothly injected.

[Liquid Crystal Compound]
The liquid crystal composition according to the present invention contains a liquid crystal compound in addition to the nanoparticles whose surface has been subjected to a hydrophobic treatment and a chiral compound. The liquid crystal compound is not limited to existing liquid crystals, and examples thereof include nematic liquid crystals, smectic liquid crystals, chiral nematic liquid crystals, and chiral smectic liquid crystals.

  The liquid crystal composition according to the present invention preferably contains a liquid crystal compound represented by the general formula (LC).

In the general formula (LC), R ^LC represents an alkyl group having 1 to 15 carbon atoms. One or more CH ₂ groups in the alkyl group may be —O—, —CH═CH—, —CO—, —OCO—, —COO— or —C, so that the oxygen atoms are not directly adjacent. ≡C— may be substituted, and one or more hydrogen atoms in the alkyl group may be optionally substituted with a halogen atom. Alkyl group R ^LC may be respectively branched chain groups, may be straight chain groups, but is preferably a linear group.

In the general formula (LC), A ^LC1 and A ^LC2 each independently represent a group selected from the group consisting of the following group (a), group (b) and group (c).
(A) trans-1,4-cyclohexylene group (one CH ₂ group present in this group or two or more CH ₂ groups not adjacent to each other may be substituted with an oxygen atom or a sulfur atom) ),
(B) 1,4-phenylene group (one CH group present in this group or two or more non-adjacent CH groups may be substituted with a nitrogen atom),
(C) 1,4-bicyclo (2.2.2) octylene group, naphthalene-2,6-diyl group, decahydronaphthalene-2,6-diyl group, 1,2,3,4-tetrahydronaphthalene-2 , 6-diyl group or chroman-2,6-diyl group.

One or two or more hydrogen atoms contained in the group (a), group (b) or group (c) may be substituted with a fluorine atom, a chlorine atom, —CF ₃ or —OCF ₃ , respectively. Good.

In the general formula (LC), Z ^LC is a single bond, —CH═CH—, —CF═CF—, —C≡C—, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —. _{, -CH 2 O -, - OCF} 2 -, - CF 2 O -, - COO- or an -OCO-.

In general formula (LC), ^YLC represents a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, and an alkyl group having 1 to 15 carbon atoms. One or more CH ₂ groups in the alkyl group may be —O—, —CH═CH—, —CO—, —OCO—, —COO—, —C, so that the oxygen atom is not directly adjacent. ≡C—, —CF ₂ O—, —OCF ₂ — may be substituted, and one or more hydrogen atoms in the alkyl group may be optionally substituted with a halogen atom.

In general formula (LC), a represents an integer of 1 to 4. When a represents 2, 3 or 4, and there are a plurality of ^ALC1s in the general formula (LC), the plurality of ^ALC1s may be the same or different, and there are a plurality of ^ZLCs A plurality of Z ^LCs may be the same or different.

  The compound represented by the general formula (LC) is preferably one or more compounds selected from the group of compounds represented by the following general formula (LC1) and general formula (LC2).

In general formula (LC1) or (LC2), R ^LC11 and R ^LC21 each independently represents an alkyl group having 1 to 15 carbon atoms, and one or more CH ₂ groups in the alkyl group are One of the alkyl groups may be substituted with —O—, —CH═CH—, —CO—, —OCO—, —COO— or —C≡C— so that the oxygen atoms are not directly adjacent. Alternatively, two or more hydrogen atoms may be optionally substituted with a halogen atom. As the compound represented by the general formula (LC1) or (LC2), R ^LC11 and R ^LC21 are each independently an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or the number of carbon atoms. An alkenyl group having 2 to 7 carbon atoms is preferable, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an alkenyl group having 2 to 5 carbon atoms are more preferable, and is further linear. The alkenyl group preferably represents the following structure.

(In the formula, it shall be bonded to the ring structure at the right end.)

In general formula (LC1) or (LC2), A ^LC11 and A ^LC21 each independently represent any one of the following structures. In the structure, one or more CH ₂ groups in the cyclohexylene group may be substituted with an oxygen atom, and one or more CH groups in the 1,4-phenylene group are nitrogen atoms. And one or more hydrogen atoms in the structure may be substituted with a fluorine atom, a chlorine atom, —CF ₃ or —OCF ₃ .

As the compound represented by the general formula (LC1) or (LC2), ^ALC11 and ^ALC21 each independently preferably have one of the following structures.

In the general formula (LC1) or ^{(LC2), X LC11, X} LC12, X LC21 ~X LC23 are each independently a hydrogen atom, a chlorine atom, a fluorine atom, a -CF ₃ or -OCF ^{_3, Y LC11} and Y ^LC21 each independently represents a hydrogen atom, a chlorine atom, a fluorine atom, a cyano group, —CF ₃ , —OCH ₂ F, —OCHF ₂ or —OCF ₃ . As the compound represented by the general formula (LC1) or (LC2), Y ^LC11 and Y ^LC21 are each independently preferably a chlorine atom, a cyano group, —CF ₃ or —OCF ₃ , and a fluorine atom or —OCF ₃ is More preferred is a fluorine atom.

In general formula (LC1) or (LC2), Z ^LC11 and Z ^LC21 each independently represent a single bond, —CH═CH—, ^{—CF═CF—} , ^—C≡C— , —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O—, —OCF ₂ —, —CF ₂ O—, —COO— or —OCO— is represented. As the compound represented by the general formula (LC1) or (LC2), Z ^LC11 and Z ^LC21 are each independently a single bond, —CH ₂ CH ₂ —, ^—COO— , ^—OCO— , —OCH ₂ —, —CH ₂ O—, —OCF ₂ — or —CF ₂ O— is preferred, and a single bond, —CH ₂ CH ₂ —, —OCH ₂ —, —OCF ₂ — or —CF ₂ O— is more preferred, and a single bond , —OCH ₂ — or —CF ₂ O— is more preferable.

In general formula (LC1) or (LC2), m ^LC11 and m ^LC21 each independently represent an integer of 1 to 4. As the compound represented by the general formula (LC1) or (LC2), ^mLC11 and ^mLC21 are preferably independently 1, 2 or 3, respectively, and when importance is attached to storage stability at low temperature and response speed. 1 or 2 is more preferable, and 2 or 3 is more preferable when improving the upper limit of the nematic phase upper limit temperature. When a plurality of A ^LC11 , A ^LC21 , Z ^LC11 and Z ^LC21 are present in the general formula (LC1) or (LC2), they may be the same or different.

  The compound represented by the general formula (LC1) is one or more compounds selected from the group consisting of compounds represented by the following general formula (LC1-a) to general formula (LC1-c). Is preferred.

In the general formula (LC1-a) ~ (LC1 -c), and R ^LC11, Y ^{LC11, X LC11} and ^{X LC12 R} LC11 is in formula each independently ^{(LC1), Y LC11, X} LC11 and ^{X LC12} Represents the same meaning. As the compounds represented by formulas (LC1-a) to (LC1-c), R ^LC11 is independently an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, An alkenyl group having 2 to 7 carbon atoms is preferable, and an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an alkenyl group having 2 to 5 carbon atoms are more preferable. ^Further, preferably a hydrogen atom or a fluorine atom ^{X LC11} and ^{X LC12} each ^{independently, Y LC11} each independently a fluorine atom, -CF ₃ or -OCF ₃ are preferred.

In general formulas (LC1-a) to (LC1-c), A ^LC1a1 , ^ALC1a2 and ^ALC1b1 are trans-1,4-cyclohexylene group, tetrahydropyran-2,5-diyl group, 1,3-dioxane. Represents a -2,5-diyl group. Further, in the general formula (LC1-a) ~ (LC1 -c), X LC1b1, X LC1b2, X LC1c1 ~X LC1c4 are each independently a hydrogen atom, a chlorine atom, a fluorine atom, a -CF ₃ or -OCF ₃ Represent. As a compound represented by general formula (LC1-a) to general formula (LC1-c), ^XLC1b1 , ^XLC1b2 , and ^{XLC1c1 to XLC1c4} are each independently preferably a hydrogen atom or a fluorine atom.

  Moreover, it is also preferable that general formula (LC1) is 1 type, or 2 or more types of compounds chosen from the group which consists of a compound represented by the following general formula (LC1-d) to general formula (LC1-m).

In the general formula (LC1-d) ~ (LC1 -m), and R ^LC11, Y ^{LC11, X LC11} and ^{X LC12 R} LC11 is in formula each independently ^{(LC1), Y LC11, X} LC11 and ^{X LC12} Represents the same meaning. As the compounds represented by the general formulas (LC1-d) to (LC1-m), R ^LC11 is independently an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or the number of carbon atoms. An alkenyl group having 2 to 7 carbon atoms is preferable, and an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an alkenyl group having 2 to 5 carbon atoms are more preferable. ^{Further, X LC11} and ^{X LC12} is preferably a hydrogen atom or a fluorine atom independently. Y ^LC11 is preferably each independently a fluorine atom, —CF ₃ or —OCF ₃ .

In general formulas (LC1-d) to (LC1-m), ^ALC1d1 , ^ALC1f1 , ^ALC1g1 , ^ALC1j1 , ^ALC1k1 , ^ALC1k2 , ^{ALC1m1 to ALC1m3} are each independently a 1,4-phenylene group. , Trans-1,4-cyclohexylene group, tetrahydropyran-2,5-diyl group, or 1,3-dioxane-2,5-diyl group.

In the general formula (LC1-d) ~ (LC1 -m), X LC1d1, X LC1d2, X LC1f1, X LC1f2, X LC1g1, X LC1g2, X LC1h1, X LC1h2, X LC1i1, X LC1i2, X LC1j1 ~X LC1j4 , ^XLC1k1 , ^XLC1k2 , ^XLC1m1 and ^XLC1m2 each independently represent a hydrogen atom, a chlorine atom, a fluorine atom, —CF ₃ or —OCF ₃ . As the compounds represented by the general formulas (LC1-d) to (LC1-m), X ^{LC1d1 to} X ^LC1m2 are each independently preferably a hydrogen atom or a fluorine atom.

In the general formulas (LC1-d) to (LC1-m), Z ^LC1d1 , Z ^LC1e1 , Z ^LC1j1 , Z ^LC1k1 , and Z ^LC1m1 are each independently a single bond, —CH═CH—, ^{—CF═CF—} , — C≡C—, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O—, —OCF ₂ —, —CF ₂ O—, —COO— or —OCO— Represent. As the compounds represented by the general formulas (LC1-d) to (LC1-m), ^{ZLC1d1 to ZLC1m1} are each independently preferably —CF ₂ O— or —OCH ₂ —.

  The general formula (LC2) is preferably one or more compounds selected from the group consisting of compounds represented by the following general formula (LC2-a) to general formula (LC2-g).

In the general formulas (LC2-a) to (LC2-g), R ^LC21 , Y ^LC21 , X ^{LC21 to} X ^LC23 are each independently R ^LC21 , Y ^LC21 , X ^{LC21 to} X ^LC23 in the general formula (LC2). Represents the same meaning. As the compounds represented by the general formulas (LC2-a) to (LC2-g), R ^LC21 is independently an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or the number of carbon atoms. An alkenyl group having 2 to 7 carbon atoms is preferable, and an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an alkenyl group having 2 to 5 carbon atoms are more preferable. X ^{LC21 to} X ^LC23 are each independently preferably a hydrogen atom or a fluorine atom, and Y ^LC21 is independently preferably a fluorine atom, —CF ₃ or —OCF ₃ .

In general formulas (LC2-a) to (LC2-g), ^{XLC2d1 to XLC2d4} , ^{XLC2e1 to XLC2e4} , ^{XLC2f1 to XLC2f4} and ^{XLC2g1 to XLC2g4} are each independently a hydrogen atom, chlorine atom, fluorine Represents an atom, —CF ₃ or —OCF ₃ ; As the compounds represented by the general formulas (LC2-a) to (LC2-g), X ^{LC2d1 to} X ^LC2g4 are each independently preferably a hydrogen atom or a fluorine atom.

In general formulas (LC2-a) to (LC2-g), Z ^LC2a1 , Z ^LC2b1 , Z ^LC2c1 , Z ^LC2d1 , Z ^LC2e1 , Z ^LC2f1 and Z ^LC2g1 are each independently a single bond, —CH═CH—, — CF═CF—, —C≡C—, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O—, —OCF ₂ —, —CF ₂ O—, —COO -Or -OCO- is represented. Examples of the compound represented by the general formula (LC2-a) ~ (LC2 -g), Z LC2a1 ~Z LC2g4 each independently _-CF 2 O-or -OCH ₂ - is preferred.

  The compound represented by the general formula (LC) is selected from the compounds represented by the following general formula (LC6) (excluding the compounds represented by the general formula (LC1) or to the general formula (LC2)). It is also preferable that it is 1 type, or 2 or more types of compounds.

In General Formula (LC6), R ^LC61 and R ^LC62 each independently represent an alkyl group having 1 to 15 carbon atoms. One or more CH ₂ groups in the alkyl group may be —O—, —CH═CH—, —CO—, —OCO—, —COO— or —C, so that the oxygen atoms are not directly adjacent. ≡C— may be substituted, and one or more hydrogen atoms in the alkyl group may be optionally halogen substituted. As the compound represented by the general formula (LC6), R ^LC61 and R ^LC62 are each independently an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or 2 to 7 carbon atoms. The alkenyl group is preferably represented by any one of the following structures.

(In the formula, it shall be bonded to the ring structure at the right end.)

In General Formula (LC6), A ^{LC61 to} A ^LC63 each independently represent any of the following structures. In the structure, one or more CH ₂ CH ₂ groups in the cyclohexylene group may be substituted with —CH═CH—, —CF ₂ O—, —OCF ₂ —. One or two or more CH groups in the phenylene group may be substituted with a nitrogen atom.

As the compound represented by the general formula (LC6), A ^{LC61 to} A ^LC63 each independently preferably has one of the following structures.

In the general formula (LC6), Z ^LC61 and Z ^LC62 each independently represent a single bond, —CH═CH—, ^—C≡C— , —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —COO—. _{, -OCH 2 -, - CH 2} O -, - OCF 2 - or _-CF 2 O-a represents, MLC61 represents 0-3. As the compound represented by the general formula (LC6), Z ^LC61 and Z ^LC62 are each independently a single bond, —CH ₂ CH ₂ —, ^—COO— , —OCH ₂ —, —CH ₂ O—, —OCF _2. - or _-CF 2 O-are preferred.

The compound represented by the general formula (LC6) is one or more compounds selected from the group consisting of compounds represented by the following general formula (LC6-a) to general formula (LC6-m). Is preferred. In general formula (LC6-a) to general formula (LC6-m), R ^LC61 and R ^LC62 are each independently an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or a carbon atom. An alkenyl group having 2 to 7 carbon atoms or an alkenyloxy group having 2 to 7 carbon atoms is represented.

[Liquid crystal display element]
The liquid crystal display element according to the present invention has the same structure as the liquid crystal display element according to the prior art except that the liquid crystal composition according to the present invention is used as the liquid crystal composition constituting the liquid crystal layer. That is, the liquid crystal display element according to the present invention has a structure in which a liquid crystal layer is sandwiched between two substrates, at least one of which is transparent. By applying electricity to the alignment film provided on the substrate and the electrode provided on the substrate, the alignment of the liquid crystal molecules is controlled. By providing a polarizing plate, a retardation film, etc., display is performed using this orientation state. The liquid crystal display element can be applied to operation modes such as TN, STN, ECB, VA, IPS, FFS, π cell, OCB, SSFLC, Polymer-Stabilized V-FLCD, cholesteric liquid crystal, and TN is particularly preferable.

  The distance (d) between the substrates of the liquid crystal display element according to the present invention is preferably in the range of 2 to 5 μm, and 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.

  The liquid crystal composition and liquid crystal display device according to the present invention reduce the operating voltage of LCD and LC-EO devices and improve the response speed compared to conventional nanoparticle-containing liquid crystal compositions with low dispersion stability of nanoparticles. Therefore, it is effective for further widespread use of high frame frequency LC-TV (120 Hz, 240 Hz) and field sequential color (FS-C) LCD characterized by low power consumption. Furthermore, it is effective in reducing the power consumption and improving the display performance of LCDs currently used such as 3D-TV, smart phone, bad computer, personal computer. Since the liquid crystal composition and the liquid crystal display element according to the present invention can realize a stable reduction in response time at a low temperature of 0 ° C. or lower, it is useful for improving the performance of the LCD.

  EXAMPLES Hereinafter, although an Example etc. are given and this invention is further explained in full detail, this invention is not limited to these Examples etc.

[Example 1]
The saturation sedimentation height (%) when the liquid crystal composition containing the nanoparticles was allowed to stand in a bottle for 2 weeks was examined, and the dispersion stability of the nanoparticles in the liquid crystal composition was examined.
When the slurry-like liquid crystal composition in which particles are dispersed is allowed to stand in a bottle, the particles gradually settle and are separated into an upper layer containing almost no particles and a lower layer in which the particles are settled. The thickness (height) of this lower layer becomes constant when left standing for a long time. The ratio of the height of the lower layer to the height of the entire liquid crystal composition in this constant state is referred to as saturated sedimentation thickness (%). The higher the dispersion stability of the particles, the lower the upper layer and the higher the saturated sedimentation thickness (%).

Specifically, in the composition described in Table 1 and Table 2, 1% by mass of fumed silica nanoparticles (in the table, “NPs (SiO ₂ )”) is added to the liquid crystal (in the table, “NLC”). Thus, a chiral compound (in the table, “chiral molecule”) was added so that the pitch was the value shown in each table, and mixed uniformly to evaluate the dispersibility. Subsequently, after putting in the bottle which can visually recognize the inside and leaving still at room temperature for 2 weeks, saturation sedimentation thickness (%) was measured. The measurement results are shown in Tables 1 and 2.

In the "NLC" column of Tables 1 and 2, NTN-02, NTN-03-Pure, NTN-03 E018, NTN-03 E088, NTN-03 B128, NTN-03 B026, NTN-03 W489, NTN-03 W098 , NTN-03 009, and NTN-03 044 all represent nematic liquid crystals (manufactured by DIC). NTN-02 is a fluorine-based liquid crystal, and NTN-03 is a cyano-based liquid crystal. Further, in the “NPs (SiO ₂ )” column of Tables 1 and 2, “R-812” is Aerosil® R-812 (fumed silica whose surface is trimethylsilylated, average primary particle size (average of nuclei) Particle size): about 7 nm, manufactured by EVONIK), “RY-300” is Aerosil (registered trademark) RY-300 (fumed silica whose surface is dimethylpolysiloxaned with dimethyl silicone oil, average primary particle size (core) Mean particle diameter): about 7 nm, manufactured by EVONIK). In the “chiral molecule” column of Tables 1 and 2, “C-1” to “C-5” mean the following chiral molecules (C-1) to (C-5). Aerosil (registered trademark) R-812 and Aerosil (registered trademark) RY-300 are both observed by the frozen replica / TEM method. As a result, nanoparticles having an irregular shape with an average particle size of about 40 nm are observed. In addition, about 7 to 10 fumed silica nanoparticles serving as nuclei were included for each particle.

  FIG. 1 shows a photograph of the appearance of the bottles 2-1 to 2-3 after standing for 2 weeks. As shown in the results of Tables 1 and 2, in various nematic liquid crystals, the saturation sedimentation thickness increased as the pitch decreased (that is, as the amount of chiral compound added increased). In particular, in the system in which the chiral compound was added so that the chiral pitch was about 12 to 14 μm, the nanoparticles were very well dispersed. From these results, mixing the hydrophobic surface-treated nanoparticles and the chiral compound together improves the long-term dispersion stability of the nanoparticles, and by mixing a sufficient amount of the chiral compound, It is clear that the stable dispersion state can be maintained without causing the nanoparticle sedimentation phenomenon. Further, in the liquid crystal composition containing both the R-type chiral compound and the L-type chiral compound as in the bottles 3-15 to 3-18, the long-term dispersion stability of the nanoparticles was improved. It was confirmed that such a liquid crystal composition is also effective for non-twisted LCDs such as VA, IPS, and FFS. In addition, the system to which chiral molecules (C-1) to (C-4) are added tends to have a higher improvement effect on the long-term dispersion stability of the nanoparticles than the system to which chiral molecules (C-5) are added. Was observed. The chiral molecules (C-1) to (C-4) have an electron withdrawing functional group, whereas the chiral molecules (C-5) have no electron withdrawing functional group. From the fact that the polarization is small, it was suggested that the use of a chiral compound having a large polarization can provide a higher effect of improving the long-term dispersion stability of the nanoparticles.

[Example 2]
Liquid crystal composition A (pitch = ∞) of only nematic liquid crystal NLC-02 (Δn = 0.125, manufactured by DIC), liquid crystal composition in which only 1.33% by mass of chiral molecule (C-1) is added to NLC-02 Product B (pitch = 12 μm (p / d = 4)), liquid crystal composition C (pitch added only 1% by mass of Aerosil® R-812 used in Example 1 to NLC-02) = ∞), liquid crystal composition D (pitch = 12 μm (p / d = 4)) was prepared.

  Next, each liquid crystal composition was injected into an NTN cell (liquid crystal layer thickness (d) = 2.5 to 3.2 μm) to prepare a liquid crystal display element. A voltage is applied to a TN liquid crystal display device made using these liquid crystal display elements at room temperature (25 ° C.) or 0 ° C. (maximum 10 V), and the light transmission amount is changed to an instantaneous multi-photometry system OPTIPRO (manufactured by Shintec Corporation). Electro-optical measurement was performed.

  A VT curve (operating voltage-transmittance characteristic) at 25 ° C. of a liquid crystal display element produced from each liquid crystal composition is shown in FIG. 2, and a VT curve at 0 ° C. is shown in FIG. 2 (A) and 3 (A) are VT curves based on the measured values, and FIGS. 2 (B) and 3 (B) are VT curves of FIGS. 2 (A) and 3 (A), respectively. , VT curve in which the transmittance at 0V is normalized to 1. As a result, when the results of the liquid crystal display element made of the liquid crystal composition A and the liquid crystal display element made of the liquid crystal composition C are compared, the threshold voltage (V (T = 90%) is obtained by adding nanoparticles at 25 ° C. when the pitch = ∞. )) Was reduced from 2.30 V to 2.14 V, and the reduction rate was -7%. When the results of the liquid crystal display element comprising the liquid crystal composition B and the liquid crystal display element comprising the liquid crystal composition D are compared, when pitch = 12 μm (p / d = 4) (when a chiral compound is added), the addition of the chiral compound As a result, the operating voltage shifted to the high voltage side, but the voltage reduction was also caused by the addition of nanoparticles. The VT curve at 0 ° C. showed a tendency similar to that at 25 ° C. In other words, the inclusion of nanoparticles with a specific size treated with a hydrophobic surface and a chiral compound can sufficiently suppress an increase in operating voltage even at a low temperature of about 0 ° C., and the response time is also extremely high. It is clear that it can be shortened.

4 and 5 show the applied voltage dependence of the response time at 0 ° C. (the time required for the light transmittance (T) to change from T (90%) to T (10%) in the NTN-LCD cell). 4 shows the process of τ _off , and FIG. 5 shows the process of τ _on . In FIG. 4, when the results of the liquid crystal display element made of the liquid crystal composition A and the liquid crystal display element made of the liquid crystal composition C are compared, the response time τ _off when the operating voltage is 5.5 V is the pitch = ∞ (p / d In the case of = ∞), the addition of nanoparticles reduced the time from 8.2 milliseconds to 5.8 milliseconds. Further, when comparing the results of the liquid crystal display element composed of the liquid crystal composition A, the liquid crystal display element composed of the liquid crystal composition B, and the liquid crystal display element composed of the liquid crystal composition D, the response time τ _{off at} the operating voltage of 5.5 V is When the chiral compound was added and p / d = 4, the time was reduced from 8.2 milliseconds to 6.2 milliseconds, and when nanoparticles were further added, the time was reduced from 8.2 milliseconds to 5.5 milliseconds. That is, the total reduction rate ([δτd] / [τd]) was −37%. Also, the value of τ _off did not depend much on the operating voltage.

  Furthermore, in order to examine the effect on the contrast ratio due to the addition of nanoparticles, a liquid crystal display using each liquid crystal composition having an addition concentration of nanoparticles of 0.1 wt% or 0.5 wt% as in Examples 1 and 2. An element was produced. The angle when these liquid crystal display elements are viewed from the front is set to “0 degree”, and then, at a viewing angle of 60 degrees on the left and right, it is continuously 2.1 to 2.3 times that before addition of the nanoparticles. ,Rose. Thereby, the contrast improvement effect by nanoparticle addition was confirmed.

Claims (6)

  The average particle diameter is 10 to 100 nm, and the nanoparticles having a hydrophobic surface treatment and a chiral compound are contained, and the content of the nanoparticles is 0.01 to 5.0% by mass. Liquid crystal composition.   The liquid crystal composition according to claim 1, wherein the pitch is 10 to 15 μm.   The liquid crystal composition according to claim 1, comprising an R-type chiral compound and an L-type chiral compound, wherein the chirality due to the R-type chiral compound and the chirality due to the L-type chiral compound are offset.   4. The nanoparticle according to claim 1, wherein the nanoparticle contains one or more nuclei selected from the group consisting of silicon dioxide, titanium oxide, aluminum oxide, zirconium oxide, and cadmium selenide. Liquid crystal composition. Furthermore, the general formula (LC)
(Wherein R ^LC represents an alkyl group having 1 to 15 carbon atoms, and one or two or more CH ₂ groups in the alkyl group are —O—, — CH = CH—, —CO—, —OCO—, —COO— or —C≡C— may be substituted, and one or more hydrogen atoms in the alkyl group are optionally substituted with halogen atoms You may,
A ^LC1 and A ^LC2 are each independently
(A) trans-1,4-cyclohexylene group (one CH ₂ group present in this group or two or more CH ₂ groups not adjacent to each other may be substituted with an oxygen atom or a sulfur atom) ),
(B) 1,4-phenylene group (one CH group present in this group or two or more CH groups not adjacent to each other may be substituted with a nitrogen atom), and (c) 1 , 4-bicyclo (2.2.2) octylene group, naphthalene-2,6-diyl group, decahydronaphthalene-2,6-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl A group or a group selected from the group consisting of a chroman-2,6-diyl group, but one or more hydrogen atoms contained in the group (a), group (b) or group (c) Each may be substituted with a fluorine atom, a chlorine atom, —CF ₃ or —OCF ₃ ,
Z ^LC is a single bond, —CH═CH—, —CF═CF—, —C≡C—, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O—, Represents —OCF ₂ —, —CF ₂ O—, —COO— or —OCO—,
Y ^LC represents a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, or an alkyl group having 1 to 15 carbon atoms, and one or two or more CH ₂ groups in the alkyl group are directly bonded to an oxygen atom. May be substituted with —O—, —CH═CH—, —CO—, —OCO—, —COO—, —C≡C—, —CF ₂ O—, —OCF ₂ — so as not to be adjacent, One or more hydrogen atoms in the alkyl group may be optionally substituted by halogen atoms;
a represents an integer of 1 to 4, but a represents 2, 3 or 4, and when there are a plurality of A ^LC1 , the plurality of A ^LC1 may be the same or different, and Z ^LC is When there are a plurality of Z ^LCs , the plurality of Z ^LCs may be the same or different. The liquid crystal composition as described in any one of Claims 1-4 containing the liquid crystalline compound represented by this.   A liquid crystal layer is sandwiched between two substrates, at least one of which is transparent, and the liquid crystal layer contains the liquid crystal composition according to any one of claims 1 to 5. Liquid crystal display element.