KR102041808B1

KR102041808B1 - Liquid crystal cell

Info

Publication number: KR102041808B1
Application number: KR1020150119521A
Authority: KR
Inventors: 김정운; 임은정; 오동현
Original assignee: 주식회사 엘지화학
Priority date: 2015-08-25
Filing date: 2015-08-25
Publication date: 2019-11-07
Also published as: KR20170024358A

Abstract

The present application relates to a liquid crystal cell and a use thereof, and can switch between a transparent mode and a scattering mode, and in particular, can provide a liquid crystal cell having excellent haze characteristics in the scattering mode. The present invention can be applied to various light modulation devices such as flexible display elements, active retarders for viewing 3D images, or viewing angle adjustment films.

Description

Liquid Crystal Cell {LIQUID CRYSTAL CELL}

The present application relates to a liquid crystal cell and its use.

Dynamic Scattering Mode (Dynamic Scattering Mode) is a kind of liquid crystal mode, refers to the liquid crystal mode that causes the electro hydro dynamic instability (EHDI). In general, as in Patent Literature 1, a dynamic scattering mode liquid crystal cell includes a liquid crystal and an additive that induces EHDI on a nematic or smectic phase. When an electric field is applied to the liquid crystal cell, convection occurs by EHDI, and the electric field increases. Subsequently, a new convection structure is created that changes into the final turbulence, causing the light to be strongly scattered for the optical anisotropy and fluid motion of the liquid crystal.

Patent Document 1: US Patent Publication No. 2006-0091358

The present application provides a liquid crystal cell and its use.

The present application relates to a liquid crystal cell. An exemplary liquid crystal cell has a liquid crystal layer containing a liquid crystal compound and a liquid crystal additive causing EHDI. In one example, the liquid crystal cell includes a chlorine-based ionic compound of Formula 1 as the liquid crystal additive. Such a liquid crystal cell of the present application switches between a transparent mode and a scattering mode, and particularly has excellent haze characteristics in the scattering mode.

[Formula 1]

A ⁺ and Cl ^-

In formula (1), A ⁺ means a monovalent cation, Cl ⁻ means a monovalent chlorine anion, and means that the monovalent cation and the monovalent chlorine anion are ionically bonded.

As the liquid crystal compound, various types of liquid crystal compounds may be used without particular limitation as long as the liquid crystal compound exists in a state in which the alignment can be switched and the optical properties of the liquid crystal cell can be adjusted by switching the alignment. As a specific example of the liquid crystal compound, a nematic liquid crystal compound or a smectic liquid crystal compound may be exemplified, but is not limited thereto. In the present application, the term "smectic phase" refers to a liquid crystal phase in which a director of the liquid crystal compound is aligned in a predetermined direction and the liquid crystal compound is arranged while forming a layer or a plane, and the term "nematic Phase ”means a liquid crystal phase in which directors of the liquid crystal compound of the liquid crystal compound are aligned in a predetermined direction, but without forming a layered structure or a planar structure. In one example, as the liquid crystal compound, a non-polymerizable or non-crosslinked liquid crystal compound having no polymerizable group or a crosslinkable group may be used in that the orientation of the liquid crystal compound may be changed by application of an external action such as a voltage.

The dielectric anisotropy of the liquid crystal compound may be appropriately selected within a range that does not impair the object of the present application. As used herein, the term "dielectric anisotropy (Δε)" means the difference (ε / /-ε ⊥) of the horizontal dielectric constant (ε / /) and the vertical dielectric constant (ε ⊥) of the liquid crystal compound. In addition, in the present specification, the term "horizontal dielectric constant (ε //)" refers to a dielectric constant value measured along the direction of the electric field in a state where a voltage is applied such that the direction of the electric field due to the optical axis of the liquid crystal compound and the applied voltage is substantially horizontal. The term "vertical dielectric constant (ε⊥)" refers to a dielectric constant value measured along the direction of the electric field in a state where a voltage is applied such that the direction of the electric field due to the optical axis of the liquid crystal compound and the applied voltage is substantially perpendicular. In the present specification, while describing the dielectric constant, it may mean a value measured while applying an electric field having a frequency of 1 kHz and a voltage of 0.1 V, unless otherwise specified.

In addition, the term "optical axis" in the present specification means an axis in the long axis direction of the liquid crystal compound when the liquid crystal compound is a rod shape, and means an axis in the normal direction of the plane of the disc when the liquid crystal compound is a discotic shape. can do. In addition, the term "vertical alignment" as used herein means that the optical axis of the liquid crystal compound is about 90 to 65 degrees, about 90 to 75 degrees, about 90 to 80 degrees, about 90 to 85 degrees or It may mean a case having an inclination angle of about 90 degrees, "horizontal alignment" means that the optical axis of the liquid crystal compound is about 0 to 25 degrees, about 0 to 15 degrees, about 0 to 10 degrees, with respect to the plane of the liquid crystal layer, It may mean a case having an inclination angle of about 0 degrees to 5 degrees or about 0 degrees.

As the liquid crystal compound, a liquid crystal compound having a negative dielectric anisotropy (Δε) can be used. In this case, the absolute value of the dielectric anisotropy (Δε) of the liquid crystal compound may be in the range of about 1 to 20, for example. The lower limit of the absolute value of the dielectric anisotropy (Δε) of the liquid crystal compound may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, or 9 or more, and the dielectric constant of the liquid crystal compound The upper limit of the absolute value of the anisotropy (Δε) may be 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, or 11 or less. When the dielectric anisotropy of the liquid crystal compound satisfies the above range, it is advantageous to implement a liquid crystal cell that switches between the transparent mode and the scattering mode.

The ionic compound present in the liquid crystal layer may cause EHDI in the liquid crystal compound. Through this, the liquid crystal compound may switch its arrangement from a regularly arranged state, for example, a transparent mode to be described later, to an irregularly arranged state, for example, a scattering mode to be described later. As described above, when using the ionic compound having a monovalent chlorine anion such as the chlorine ionic compound of Formula 1, the liquid crystal cell may exhibit excellent haze characteristics in the scattering mode.

The ionic compound may be a compound in the form of a salt comprising a monovalent cation and a monovalent chlorine anion. The monovalent cation can be used without particular limitation as long as it can ion-bond with monovalent chlorine anion to form a salt-type compound. Examples of such ionic compounds include, but are not limited to, nitrogen-containing onium salts, sulfur-containing onium salts, and phosphorus-containing onium salts.

The ionic compound may include a cation represented by one of the following Chemical Formulas 2 to 5 as the monovalent cation.

[Formula 2]

In Formula 2, Z is a nitrogen, sulfur or phosphorus atom, R ₁ , R _m , R _n and R _o are each independently hydrogen or a monovalent hydrocarbon group having 1 to 20 carbon atoms, provided that Z is a sulfur atom , R _o does not exist.

[Formula 3]

In formula (3), R _a is _a divalent hydrocarbon group having 4 to 20 carbon atoms, and R _b and R _c are each hydrogen or a monovalent hydrocarbon group having 1 to 20 carbon atoms, provided that a nitrogen atom (N) is a double bond If included, R _b or R _c are absent.

[Formula 4]

In formula (4), R _d is a divalent hydrocarbon group having 2 to 20 carbon atoms, and R _e , R _f and R _g are each hydrogen or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[Formula 5]

In formula (5), R _h is a divalent hydrocarbon group having 2 to 20 carbon atoms, and R _i , R _j and R _k are each hydrogen or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

The hydrocarbon group in Chemical Formulas 2 to 5 includes a saturated hydrocarbon group and an unsaturated hydrocarbon group, and the hydrocarbon group may include two or more of a carbon-carbon single bond carbon-carbon double bond and a carbon-carbon triple bond. In addition, the hydrocarbon group in Chemical Formulas 2 to 5 may include a straight chain or branched hydrocarbon group. In addition, the hydrocarbon group in Chemical Formulas 2 to 5 may include a hetero atom as necessary. In addition, in Formula 3, any one of Rb or Rc may be connected to any one carbon of Ra to form a hydrocarbon ring structure.

The ionic compound may include a cation represented by one of Chemical Formulas 6 to 11 as a monovalent cation.

[Formula 6]

[Formula 7]

[Formula 8]

[Formula 9]

[Formula 10]

[Formula 11]

In Formulas 6 to 11, R ₁ To R ₄ are each independently an alkyl group having 1 to 20 carbon atoms.

More specifically, as the cation represented by the formula (2), for example, a tetraalkylammonium cation, a trialkylsulfonium cation, a tetraalkylphosphonium cation, or a part of the alkyl group is an alkenyl group, an alkoxyl group, or an epoxy group. Substituted thing etc. are mentioned. Examples of such cations include tetramethylammonium cation, tetraethylammonium cation, tetrapropylammonium cation, tetrabutylammonium cation, tetrapentylammonium cation, tetrahexylammonium cation, tetraheptylammonium cation, trimethylhexadecylammonium cation, triethylmethyl Ammonium cation, tributylethylammonium cation, trimethyldecylammonium cation, trioctylmethylammonium cation, tripentylbutylammonium cation, trihexylmethylammonium cation, trihexylpentylammonium cation, triheptylmethylammonium cation, triheptylhexyl ammonium cation , N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium cation, glycidyltrimethylammonium cation, diallyldimethylammonium cation, N, N-dimethyl-N, N- Dipropylammonium cation, N, N-dimethyl-N, N-dihexylammonium cation, N, N-dipe Lofil-N, N-dihexylammonium cation, N, N-dimethyl-N-ethyl-N-propylammonium cation, N, N-dimethyl-N-ethyl-N-butylammonium cation, N, N-di Methyl-N-ethyl-N-pentylammonium cation, N, N-dimethyl-N-ethyl-N-hexylammonium cation, N, N-dimethyl-N-ethyl-N-heptylammonium cation, N, N- Dimethyl-N-propyl-N-butylammonium cation, N, N-dimethyl-N-propyl-N-pentylammonium cation, N, N-dimethyl-N-propyl-N-hexylammonium cation, N, N -Dimethyl-N-propyl-N-heptylammonium cation, N, N-dimethyl-N-butyl-N-hexylammonium cation, N, N-dimethyl-N-butyl-N-heptylammonium cation, N, N-dimethyl-N-pentyl-N-hexylammonium cation, N, N-dimethyl-N-hexyl-N-heptylammonium cation, trimethylheptylammonium cation, N, N-diethyl-N-methyl-N -Propyl ammonium cation, N, N-diethyl-N-methyl-N-pentylammonium cation, N, N-diethyl-N-methyl-N-heptylammonium cation, N, N-diethyl -N-propyl-N-pentylammonium cation, triethylmethylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylheptylammonium cation, N, N-dipropyl-N-methyl-N-ethylammonium Cation, N, N-dipropyl-N-methyl-N-pentylammonium cation, N, N-dipropyl-N-butyl-N-hexylammonium cation, N, N-dibutyl-N-methyl-N-pentyl Ammonium cation, N, N-dibutyl-N-methyl-N-hexylammonium cation, trioctylmethylammonium cation, N-methyl-N-ethyl-N-propyl-N-pentylammonium cation, trimethylsulfonium cation, Triethylsulfonium cation, tributylsulfonium cation, trihexylsulfonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, dimethyldecylsulfonium cation, tetramethylphosphonium cation, tetraethylphosphonium cation Tetrabutyl phosphonium cation, tetrapentyl phospho Cation, tetrahexylphosphonium cation, tetraheptylphosphonium cation, tetraoctylphosphonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium cation, and the like. It doesn't happen.

As a cation represented by the said Formula (3), a pyridinium cation, a piperidinium cation, a pyrrolidinium cation, the cation which has a pyrroline skeleton, the cation which has a pyrrole skeleton, etc. are mentioned, for example. Examples of such cations include 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1 -Hexyl-3-methylpyridinium cation, 1-butyl-3,4-dimethylpyridinium cation, 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-methyl -1-propylpyrrolidinium cation, 2-methyl-1-pyrroline cation, 1-ethyl-2-phenylindole cation, 1,2-dimethylindole cation, 1-ethylcarbazole cation, etc. It is not limited to this.

As a cation represented by the said Formula (4), an imidazolium cation, a tetrahydropyrimidinium cation, a dihydropyrimidinium cation, etc. are mentioned, for example. Examples of such cations include 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation 1-hexyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, 1,2-dimethyl-3-propylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-2,3 -Dimethylimidazolium cation, 1-hexyl-2,3-dimethylimidazolium cation, 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3 -Trimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3 , 5-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,3-dimethyl-1,4-dihydro Limidinium cation, 1,3-dimethyl-1,6-dihydropyrimidinium cation, 1,2,3-trimethyl-1,4-dihydropyrimidinium cation, 1,2,3-tri Methyl-1,6-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,6- Dihydropyrimidinium cation may be exemplified, but is not limited thereto.

As a cation represented by General formula (5), a pyrazolium cation, a pyrazolinium cation, etc. are mentioned, for example. Examples of such cations include, but are not limited to, 1-methylpyrazolium cation, 3-methylpyrazolium cation, 1-ethyl-2-methylpyrazolinium cation, and the like.

Specific examples of the cation include trimethylhexadecylammonium cation, 1-butyl-4-methylpyridinium cation, triethylmethylammonium cation, tributylethylammonium cation, trimethyldecylammonium cation, trioctylmethylammonium cation and tri Pentylbutylammonium cation, trihexylmethylammonium cation, trihexylpentylammonium cation, triheptylmethylammonium cation, triheptylhexylammonium cation, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium Cation, glycidyltrimethylammonium cation, N, N-dimethyl-N-ethyl-N-propylammonium cation, N, N-dimethyl-N-ethyl-N-butylammonium cation, N, N-dimethyl -N-ethyl-N-pentylammonium cation, N, N-dimethyl-N-ethyl-N-hexylammonium cation, N, N-dimethyl-N-ethyl-N-heptylammonium cation, N, N-di Methyl-N-ethyl-N-nonylammonium cation, N, N-dimethyl-N-propyl-N-butylammonium Cation, N, N-dimethyl-N-propyl-N-pentylammonium cation, N, N-dimethyl-N-propyl-N-hexylammonium cation, N, N-dimethyl-N-propyl-N-heptyl Ammonium cation, N, N-dimethyl-N-butyl-N-hexylammonium cation, N, N-dimethyl-N-butyl-N-heptylammonium cation, N, N-dimethyl-N-pentyl-N- Hexylammonium cation, N, N-dimethyl-N-hexyl-N-heptylammonium cation, N, N-dimethyl-N, N-dihexylammonium cation, trimethylheptylammonium cation, N, N-diethyl- N-methyl-N-propylammonium cation, N, N-diethyl-N-methyl-N-pentylammonium cation, N, N-diethyl-N-methyl-N-heptylammonium cation, N, N-diethyl -N-propyl-N-pentylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylheptylammonium cation, N, N-dipropyl-N-methyl-N-ethylammonium cation, N, N- Dipropyl-N-methyl-N-pentylammonium cation, N, N-dipropyl-N-view Tyl-N-hexylammonium cation, N, N-dipropyl-N, N-dihexylammonium cation, N, N-dibutyl-N-methyl-N-pentylammonium cation, N, N-dibutyl-N- Tetraalkylammonium cations such as methyl-N-hexylammonium cation, N-methyl-N-ethyl-N-propyl-N-pentylammonium cation, trimethylsulfonium cation, triethylsulfonium cation, tributylsulfonium cation, Trialkylsulfonium cations such as trihexylsulfonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, dimethyldecylsulfonium cation, tetramethylphosphonium cation, tetraethylphosphonium cation, tetrabutylphosphonium Cation, tetrapentylphosphonium cation, tetrahexylphosphonium cation, tetraheptylphosphonium cation, tetraoctylphosphonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium Tetraalkyl phosphonium cations such as cations may be selected and used, but is not limited thereto.

The ratio of the ionic compound in the liquid crystal layer may be appropriately selected in consideration of the desired physical properties, for example, a property that may cause an irregular arrangement state of the liquid crystal compound. The proportion of the ionic compound in the liquid crystal layer may be, for example, in the range of 0.005% by weight to 10.0% by weight. More specifically, the lower limit of the content ratio of the ionic compound in the liquid crystal layer is at least 0.005 wt%, at least 0.01 wt%, at least 0.05 wt%, at least 0.1 wt%, at least 0.2 wt%, at least 0.5 wt%, and at most 1.0 wt%. Or at least 1.5 wt%, at least 2.0 wt%, at least 2.5 wt%, at least 3.0 wt%, at least 3.5 wt%, at least 4.0 wt% or at least 4.5 wt%. The upper limit of the content ratio of the ionic compound in the liquid crystal layer is 10.0 wt% or less, 9.5 wt% or less, 9.0 wt% or less, 8.5 wt% or less, 8.0 wt% or less, 7.5 wt% or less, 7.0 wt% or less, 6.5 Up to 6.0 wt% or up to 5.5 wt%. When the ratio of the ionic compound in the liquid crystal layer satisfies the above range, a liquid crystal cell capable of switching between the transparent mode and the scattering mode having excellent haze characteristics may be implemented.

The liquid crystal cell may switch between the transparent mode and the scattering mode by adjusting an initial alignment state of the liquid crystal compound and applying an external action such as a voltage. For example, when the liquid crystal compound is present in an aligned state, the liquid crystal cell may exhibit a transparent mode, and when the liquid crystal compound is present in an irregularly arranged state, the liquid crystal cell may exhibit a scattering mode.

As used herein, the term "scattering mode" may refer to a mode in which a liquid crystal cell exhibits a predetermined level or more of haze, and the term "transparent mode" may refer to a state in which light can be transmitted or a mode indicating a haze of a predetermined level or less. .

For example, in the scattering mode, the liquid crystal cell has a haze of 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55 Or at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95%. In the transparent mode, the liquid crystal cell may have, for example, a haze of less than 10%, 8% or less, 6% or less, or 5% or less. The haze may be a percentage of the transmittance of the diffused light to the transmittance of the total transmitted light passing through the measurement object. The haze can be evaluated using a haze meter (NDH-5000SP). Haze can be evaluated in the following manner using the haze meter. That is, light is made to pass through the measurement object and to enter the integrating sphere. In this process, light is divided into diffused light (DT) and parallel light (PT) by a measurement object, and the light is reflected in an integrating sphere and collected by a light receiving element, and the haze can be measured through the light. Do. That is, the total transmitted light TT is the sum of the diffused light DT and the parallel light PT (DT + PT), and the haze is the percentage of diffused light with respect to the total transmitted light (Haze (%) = 100). X DT / TT).

1 exemplarily illustrates driving of a liquid crystal cell using a liquid crystal compound having a negative dielectric anisotropy. As shown in FIG. 1, in an initial state, that is, in a state in which no external action is applied, the liquid crystal compound may exist in a vertically oriented state with respect to the plane of the liquid crystal layer, and may implement the transparent mode A. FIG. In this case, in order to adjust the initial alignment state of the liquid crystal compound, a vertical alignment layer described later may exist on both sides of the liquid crystal layer. In this initial state, when an external action, for example, a vertical electric field is applied, the liquid crystal compound is switched to the scattering mode (B) while having an irregular arrangement by EHDI caused by an ionic compound (not shown) which is a liquid crystal additive. Can be.

In one example, when the liquid crystal compound is a nematic phase, when the vertical electric field is removed, the liquid crystal compound may be switched to the transparent mode of the initial state. In another example, the scattering mode may be maintained even when the vertical electric field is removed when the liquid crystal compound is a smetic phase, for example, the Smetic A phase. That is, when the liquid crystal on the nematic phase is used, the liquid crystal cell may implement a monostable mode, and when the liquid crystal on the smectic phase is used, the liquid crystal cell may implement a bistable mode. In the present application, the term "monostable mode" refers to a mode in which application of external energy is continuously required to maintain at least one of the states of the liquid crystal, and the term "bistable mode" requires external energy only when the state changes. It means the mode.

The transition from the transparent mode to the scattering mode can be performed, for example, by applying a low frequency vertical electric field in the range of about 1 Hz to 500 Hz. In addition, in the case where the liquid crystal compound is a smear phase, in order to switch from the scattering mode to the transparent mode, application of a relatively high frequency, for example, a high frequency of 1 kHz or more may be required. However, the frequency range of the applied electric field is not limited to the above, and may be appropriately changed in consideration of target properties, for example, haze characteristics or transmission characteristics of each mode.

The liquid crystal cell may further include an anisotropic dye in the liquid crystal layer. The anisotropic dye can improve the transmittance variable characteristic of a liquid crystal cell, for example by reducing the transmittance in a scattering mode. As used herein, the term "dye" may mean a material capable of intensively absorbing and / or modifying light in at least part or the entire range within the visible light region, for example, in the 400 nm to 700 nm wavelength range, The term "anisotropic dye" may refer to a material capable of anisotropic absorption of light in at least part or the entire range of the visible light region.

As the anisotropic dye, for example, a known dye known to have a property that can be aligned according to the alignment state of the liquid crystal compound can be selected and used. As the anisotropic dye, for example, a black dye can be used. Such dyes are known, for example, but not limited to azo dyes, anthraquinone dyes, and the like.

The liquid crystal cell may further include two substrates disposed on both sides of the liquid crystal layer. In this case, as shown in FIG. 2, the exel cell 1 replaces the liquid crystal layer 101 existing between two opposing substrates 201A and 201B and the two opposing substrates 201A and 201B. It may include.

As the substrate, a known material can be used without particular limitation. For example, inorganic films, plastic films, etc., such as a glass film, a crystalline or amorphous silicon film, a quartz, or an Indium Tin Oxide (ITO) film, can be used. As the substrate, an optically isotropic substrate, an optically anisotropic substrate such as a retardation layer, a polarizing plate, a color filter substrate, or the like can be used.

Examples of the plastic substrate include triacetyl cellulose (TAC); COP (cyclo olefin copolymer) such as norbornene derivatives; Poly (methyl methacrylate); PC (polycarbonate); PE (polyethylene); PP (polypropylene); PVA (polyvinyl alcohol); DAC (diacetyl cellulose); Pac (Polyacrylate); PES (poly ether sulfone); PEEK (polyetheretherketon Substrates including polyphenylsulfone (PPS), polyetherimide (PEI); polyethylenemaphthatlate (PEN); polyethyleneterephtalate (PET); polyimide (PI); polysulfone (PSF); polyarylate (PAR) or amorphous fluorine resin The substrate may have a coating layer of a silicon compound such as gold, silver, silicon dioxide or silicon monoxide, or a coating layer such as an antireflection layer, if necessary.

The liquid crystal cell may further include two electrode layers disposed on both sides of the liquid crystal layer. In this case, the liquid crystal cell may include two liquid crystal layers disposed between two electrode layers disposed opposite to each other and the two electrode layers disposed opposite to each other. When the liquid crystal layer includes both the two oppositely disposed substrates and two oppositely disposed electrode layers, as shown in FIG. 3, the liquid crystal cell 2 is formed of the electrode layers 301A and 301B and the substrates 201A and 201B. In order to be closer to the liquid crystal layer 101 may be disposed.

The electrode layer may apply a vertical or horizontal electric field to the liquid crystal layer so as to switch the alignment state of the liquid crystal compound in the liquid crystal layer. For example, the electrode layer may be formed by depositing a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as indium tin oxide (ITO). The electrode layer may be formed to have transparency. In this field, various materials and forming methods capable of forming a transparent electrode layer are known, and all of these methods can be applied. If necessary, the electrode layer formed on the surface of the substrate may be appropriately patterned.

The liquid crystal cell may further include two vertical alignment layers disposed on both sides of the liquid crystal layer. In this case, the liquid crystal cell may include two liquid crystal layers that are disposed between two vertically aligned layers and two vertically aligned layers that face each other. When the liquid crystal layer includes both the two oppositely disposed substrates, the two oppositely disposed electrode layers and the two oppositely aligned vertical alignment films, as shown in FIG. 4, the liquid crystal cell 3 includes a vertically aligned film 401A, 401B, the electrode layers 301A and 301B, and the substrates 201A and 201B may be disposed to be further adjacent to the liquid crystal layer 101.

As the vertical alignment film, any alignment film having vertical alignment capability with respect to the liquid crystal compound of the adjacent liquid crystal layer can be selected and used without particular limitation. As such an alignment film, for example, an alignment film known to be capable of exhibiting orientation characteristics by a non-contact method such as irradiation of linearly polarized light including a contact alignment film or a photoalignment film compound, such as a rubbing alignment film, can be used.

The present application also relates to the use of the liquid crystal cell. In the exemplary liquid crystal cell, the exemplary liquid crystal cell switches between the transparent mode and the scattering mode, and is particularly excellent in the haze characteristic in the scattering mode. Such a liquid crystal cell may be usefully used in an optical modulation device. As the optical modulation device, a smart window, a window protective film, a flexible display element, an active retarder for viewing 3D images, a viewing angle adjusting film, or the like may be exemplified, but is not limited thereto. The method of configuring the optical modulation device as described above is not particularly limited, and a conventional method may be applied as long as the liquid crystal cell is used.

The present invention can provide a liquid crystal cell that switches between the transparent mode and the scattering mode, and particularly has excellent haze characteristics in the scattering mode, and the liquid crystal cell is used for a smart window, a window protective film, a flexible display element, and a 3D image display. It can be applied to various light modulation devices such as an active retarder or a viewing angle adjusting film.

1 exemplarily illustrates a driving method of a liquid crystal cell of the present application.
2 to 4 exemplarily illustrate a liquid crystal cell of the present application.
5 is a haze evaluation result according to the voltage of Examples 1 and 2. FIG.
6 is a haze evaluation result according to the voltages of Comparative Examples 1 and 2. FIG.

Hereinafter, the above contents will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present application is not limited by the contents given below.

Example One

DSM (Dynamic Scattering Mode) Preparation of Liquid Crystal Composition

3.96 g of HCCH's liquid crystal (HNG726200-100, dielectric anisotropy: -4.0, refractive index anisotropy: 0.225) and CTAC (Hexadecyltrimethylammonium Chloride, Sigma) 0.04 g (about 1% by weight) were added to a 10 mL vial. After the addition, the mixture was stirred at 100 ° C. for 24 hours to prepare a liquid crystal composition.

DSM (Dynamic Scattering Mode) Liquid crystal cell Produce

A transparent electrode layer and a vertical alignment layer were sequentially formed inside the cell, and a liquid crystal cell was prepared by injecting the prepared liquid crystal composition using a capillary phenomenon into a glass test cell having a cell gap of 9 um.

Example 2

In the preparation of the liquid crystal composition, a liquid crystal cell in the same manner as in Example 1 except that 0.04 g (about 1 wt%) of BMC (1-Butyl-4-methylpyridinium Chloride, Sigma) was used instead of CTAC as a liquid crystal additive. Was prepared.

Comparative example One

In preparing the liquid crystal composition, a liquid crystal cell was manufactured in the same manner as in Example 1, except that 0.04 g (about 1 wt%) of CTAB (Hexadecyltrimethylammonium Bromide, TCI, Inc.) was used instead of CTAC as the liquid crystal additive.

Comparative example 2

In the preparation of the liquid crystal composition, a liquid crystal cell in the same manner as in Example 1 except that 0.04 g (about 1 wt%) of BMB (1-Butyl-4-methylpyridinium Bromide, TCI Co., Ltd.) was used instead of CTAC as a liquid crystal additive. Was prepared.

Evaluation example One Haze evaluation

Using the haze meter, NDH-5000SP for the liquid crystal cells prepared in Examples and Comparative Examples, after evaluating the haze according to the voltage by the ASTM method, the results are shown in Tables 1 and 5 (Examples 1 and 2) to FIG. 6 (Comparative Examples 1 and 2). Specifically, the haze of each applied voltage was measured while connecting and driving an AC power source to the upper and lower transparent electrode layers of the liquid crystal cell to apply a vertical electric field to the liquid crystal cell.

According to voltage
Haze (%) Example 1
(CTAC) Example 2
(BMC) Comparative Example 1
(CTAB) Comparative Example 2
(BMB) 30 V 84.6 84.6 72.0 65.5 50 V 87.6 87.1 78.3 74.7 60 V 86.0 85.4 81.2 76.9

101: liquid crystal layer
102: liquid crystal compound
201A, 201B: Substrate
301A, 301B: electrode layer
401A, 401B: vertical alignment layer

Claims

It has a liquid crystal layer containing a liquid crystal compound and a chlorine-based ionic compound of formula (1),
A liquid crystal cell that realizes a transparent mode with a haze of less than 10% when no external action is applied and switches to a scattering mode with a haze of 10% or more when an external action is applied:
[Formula 1]
A ⁺ and Cl ^-
In formula (1), A ⁺ means a monovalent cation of formula (7), Cl ⁻ means a monovalent chlorine anion, and means that the monovalent cation and the monovalent chlorine anion are ionically bonded.
[Formula 7]

In formula (7), R ₁ to R ₄ are each independently an alkyl group having 1 to 20 carbon atoms.

The liquid crystal cell according to claim 1, wherein the liquid crystal compound is a nematic phase or a smetic phase liquid crystal compound.

The liquid crystal cell of claim 1, wherein the liquid crystal cell has a negative dielectric anisotropy (Δε). (The dielectric anisotropy (Δε) is a difference between the horizontal dielectric constant (ε //) and the vertical dielectric constant (ε⊥) of the liquid crystal compound. ε //-ε⊥)).

The liquid crystal cell according to claim 3, wherein an absolute value of dielectric anisotropy (Δε) of the liquid crystal compound is in a range of 1 to 20.

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The liquid crystal cell according to claim 1, wherein a ratio of the ionic compound in the liquid crystal layer is in a range of 0.005 wt% to 10.0 wt%.

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The liquid crystal cell of claim 1, wherein the liquid crystal compound is in a vertically aligned state in which no external action is applied.

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The liquid crystal cell of claim 1, further comprising two substrates disposed on opposite sides of the liquid crystal layer.

The liquid crystal cell of claim 1, further comprising two vertical alignment layers disposed on opposite sides of the liquid crystal layer.

The liquid crystal cell of claim 1, further comprising two electrode layers disposed on both sides of the liquid crystal layer.

An optical modulation device comprising the liquid crystal cell of claim 1.

Smart window comprising the liquid crystal cell of claim 1.