KR20190071428A - Liquid crystal cell - Google Patents

Abstract

The present application relates to a liquid crystal cell and a use thereof. More particularly, the present application may provide a liquid crystal cell in which a scattering mode delay phenomenon partially occurring when applying a voltage for switching from a transmission mode to a scattering mode is reduced; and a use of the liquid crystal cell. The liquid crystal cell may be applied to various light modulators such as a smart window, a window protective film, a flexible display device, a transparent display shading plate, an active retarder for 3D image display, or a viewing angle adjusting film, etc.

Description

Liquid crystal cell {LIQUID CRYSTAL CELL}

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

A normal transmission mode element is a device in which a transmission mode is realized in the absence of an external action, a switching mode is switched to an interrupting mode under an external action, and the transmission mode is switched to a transmission mode again when an external action is removed.

Patent Document 1 discloses a normal transmission mode element capable of varying between a transmission mode and a scattering mode. The device of Patent Document 1 operates in the cut-off mode while driving in the scattering mode when voltage is applied in the transmission mode when the voltage is not applied, by adding the conductivity adjusting agent in the liquid crystal.

However, in the conventional transmission mode device in which the conductivity adjusting agent is added to the liquid crystal of Patent Document 1, the area away from the electrode due to addition of the conductivity adjusting agent in the liquid crystal due to IR drop (Current & Resistor Drop) Therefore, there is a problem that the scattering mode is delayed in a certain region and visually recognized. Therefore, it is necessary to develop a conventional transmission mode device which can solve the above problems.

Korean Patent Publication No. 2016-0115428

The present application is to provide a liquid crystal cell in which the scattering mode delay phenomenon, which is normally generated in a transmission mode and partially occurs when a voltage is applied to switch to a scattering mode, is improved, and its use.

This application relates to a liquid crystal cell. Hereinafter, the liquid crystal cell of the present application will be described with reference to the accompanying drawings, and the attached drawings are illustrative, and the liquid crystal cell of the present application is not limited to the attached drawings.

Figs. 1 to 4 respectively illustrate a liquid crystal cell according to an embodiment of the present application. 1 to 4, the liquid crystal cell includes a first substrate 100, a liquid crystal layer 200, and a second substrate 300 sequentially.

The liquid crystal cell may be a transmissive mode device. In this specification, the term " normal transmission mode element " means that a transmission mode is realized in a state in which there is no external action (i.e., an initial state or a normal state) and is switched to a scattering mode under external action. May be referred to as a switching device. As used herein, the term " external action " refers to all kinds of actions performed to change the alignment of a liquid crystal compound, and representative examples include the application of a voltage.

The first substrate 100 and / or the second substrate 300 may have a surface roughness Ra of 30 nm or more in a state including the alignment layers 130 and 330. Specifically, the first substrate 100 and / or the second substrate 300 may have a surface roughness of 31 nm or more, 32 nm or more, 33 nm or more, 34 nm or more or 35 nm or more, nm. The upper limit of the surface roughness may be 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 45 nm or less or 43 nm or less. The first substrate 100 and / or the second substrate 300 may be formed by switching the liquid crystal cell from the transmissive mode to the scattering mode by satisfying the above-described range of the surface roughness Ra in the state including the alignment layers 130 and 330. [ It is possible to improve the movement of the non-reactive liquid crystal, thereby improving the scattering mode delay phenomenon.

The surface roughness may be, for example, a) a step of coating a composition comprising beads, a resin and a solvent on a substrate, followed by drying or further curing the composition; b) stamping the substrate with a mold; c) eroding the flat substrate with a partially erodible solvent; And d) applying a physical force to the flat substrate. The surface roughness according to one embodiment is obtained by coating a composition including beads 101, a resin and a solvent on electrode films 110 and 310 and then drying to form resin layers 120 and 320, 120, and 320, as shown in FIG. The surface roughness according to another embodiment is obtained by a process of coating an alignment film composition including beads 101, an orientation resin and a solvent on electrode films 110 and 310 and then drying to form alignment films 130 and 330 .

In one example, the first substrate 100 and / or the second substrate 300 having the surface roughness of 30 nm or more include the electrode films 110 and 310 and the alignment films 130 and 330, , 330, and the like. 1, the first substrate 100 and the second substrate 300 sequentially include electrode films 110 and 310 and alignment films 130 and 330, and the alignment films 130 and 130, 2, the first substrate 100 may include an electrode film 110 and an orientation film 130 in sequence, and the first substrate 100 may include an electrode film 110 and an orientation film 130, The second substrate 300 may further include an electrode film 310 and an alignment film 330 in order and the alignment film 330 may be formed with a plurality of It may not contain beads.

In another example, the first substrate 100 and / or the second substrate 300 having the surface roughness of 30 nm or more include the electrode films 110 and 310, the resin layers 120 and 320, and the alignment films 130 and 330 And may further include a bead 101 to which a part is fixed by the resin layers 120 and 320 and the alignment layers 130 and 330. 3, each of the first substrate 100 and the second substrate 300 includes the electrode films 110 and 310, the resin layers 120 and 320, and the alignment films 130 and 330 in sequence The first substrate 100 may further include a bead 101 to which a part is fixed by the resin layers 120 and 320 and the orientation films 130 and 330. As shown in FIG. 4, And may further include a bead 101 including a film 110, a resin layer 120 and an orientation film 130 sequentially and having a part fixed by the resin layer 120 and the orientation film 130, The second substrate 200 may include an electrode film 310, a resin layer 320 and an alignment layer 330 in order. The resin layer 320 and the alignment layer 330 may not include beads.

In one example, the first substrate 100 and / or the second substrate 300 having the surface roughness of 30 nm or more include the electrode films 110 and 310 and the alignment films 130 and 330, 330, the thickness of the alignment layer 130, 330 may be between 30 nm and 250 nm. In the present specification, the term " thickness of alignment film " refers to the thickness of the alignment film (130, 330) in the process of forming the alignment films 130 and 330 by applying the alignment film composition including the beads 101 and the aligning resin on the electrode films 110 and 310 330 may mean the thickness of the alignment layers 130 and 330 formed on the electrode films 110 and 310 except for the size of the protruded portion of the beads 101 formed on the electrode films 130 and 330. More specifically, the thickness of the alignment layers 130 and 330 may be 50 nm or more, 70 nm or more, 90 nm or more, 110 nm or 130 nm or more, and the upper limit may be 230 nm or less, Or less, or 170 nm or less, or 150 nm or less. The alignment layers 130 and 330 may have a thickness within the range described above so that the diameter of the beads 101 is greater than the thickness of the alignment layers 130 and 330, 2 substrate 300 may have an excellent surface roughness in a state including the alignment films 130 and 330 so that a scattering mode delay that occurs partially in the voltage application for switching the liquid crystal cell from the transmissive mode to the scattering mode The phenomenon can be improved.

In this case, the diameter of the beads 101 may be greater than the thickness of the alignment layers 130 and 330 to satisfy the surface roughness of the first substrate 100 and / or the second substrate 300 . For example, the lower limit of the diameter of the beads 101 may be 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more or 90 nm or more, the upper limit of the diameter of the beads 101 is 500 nm or less And may be 400 nm or less. The bead 101 has a diameter within the above range so that the first substrate 100 and / or the second substrate 300 can have excellent surface roughness including the alignment layers 130 and 330, This can improve the scattering mode delay phenomenon that occurs partially when a voltage is applied to switch the liquid crystal cell from the transmission mode to the scattering mode.

In another example, the first substrate 100 and / or the second substrate 300 having the surface roughness of 30 nm or more include the electrode films 110 and 310, the resin layers 120 and 320, and the alignment films 130 and 330 The resin layers 120 and 320 and the alignment layers 130 and 330 may be formed on the resin layer 120 and 320 and the alignment layers 130 and 330, ) May be from 60 nm to 400 nm. In the present specification, the term " sum of the thicknesses of the resin layer and the orientation film " means that the composition including the beads 101 and the resin is applied on the electrode films 110 and 310 to form the resin layers 120 and 320, In the process of forming the alignment layers 130 and 330 by applying an alignment layer composition containing an orienting resin on the resin layers 120 and 320, the projected portions of the beads 101 formed on the alignment layers 130 and 330 The thicknesses of the resin layers 120 and 320 and the alignment layers 130 and 330 formed on the electrode films 110 and 310 may be the same. Specifically, the sum of the thicknesses of the resin layers 120 and 320 and the orientation films 130 and 330 may be 100 nm to 350 nm, 140 nm to 300 nm, 180 nm to 250 nm, or 190 nm to 210 nm. When the sum of the thicknesses of the resin layers 120 and 320 and the alignment layers 130 and 330 satisfies the above-described range, the diameter of the beads 101 becomes larger than the diameter of the resin layers 120 and 320 and the alignment layers 130 and 330, The first substrate 100 and / or the second substrate 300 have excellent surface roughness in a state including the resin layers 120 and 320 and the orientation films 130 and 330 And thereby, it is possible to improve the scattering mode delay phenomenon that occurs partially in the voltage application for switching the liquid crystal cell from the transmissive mode to the scattering mode.

In this case, the diameter of the beads 101 may be controlled by adjusting the diameter of the resin layers 120 and 320 and the orientation films 130 and 130 to satisfy the surface roughness of the first substrate 100 and / or the second substrate 300, 330). ≪ / RTI > For example, the lower limit of the diameter of the bead 101 may be 80 nm or more, 90 nm or more, 100 nm or more, 110 nm or 120 nm or more, the upper limit of the diameter of the bead 101 is 700 nm or less, And may be 600 nm or less. The bead 101 has a diameter within the above range so that the first substrate 100 and / or the second substrate 300 can have excellent surface roughness including the alignment layers 130 and 330, This can improve the scattering mode delay phenomenon that occurs partially when a voltage is applied to switch the liquid crystal cell from the transmission mode to the scattering mode.

The thickness of the liquid crystal layer 200 is set to be greater than the thickness of the beads 101 protruded on the alignment layers 130 and 330 when the first substrate 100 and / or the second substrate 300 include the alignment layers 130 and 330, The difference between the diameter of the bead 101 and the thickness of the orientation film 130 or 330 formed on the first substrate 100 and / or the second substrate 300 or the difference between the diameter of the bead 101 and the thickness of the first The difference in thickness including the resin layers 120 and 320 and the alignment layers 130 and 330 formed on the substrate 100 and / or the second substrate 300 may be greater than the difference in thickness. For example, the thickness of the liquid crystal layer 200 may be in the range of 3 탆 to 20 탆. Specifically, the thickness of the liquid crystal layer 200 may be 4 占 퐉 or more, 5 占 퐉 or more, 6 占 퐉 or more, or 7 占 퐉 or more, and the upper limit may be 19 占 퐉 or less, 18 占 퐉, 17 占 퐉, 15 mu m or less. The thickness of the liquid crystal layer 200 is preferably from 7 탆 to 15 탆.

The electrode films 110 and 310 may include a base film and an electrode layer on the base film.

As the base film, those having optical transparency can be used. For example, an optically transparent plastic film or sheet may be used as the one base film, or glass may be used. Specifically, the plastic film or sheet may be a cellulose film or sheet such as DAC (diacetyl cellulose) or TAC (triacetyl cellulose) film or sheet; A cycloolefin copolymer (COP) film or sheet such as a norbornene derivative resin film or sheet; An acrylic film or sheet such as PMMA (poly (methyl methacrylate) film or sheet; a polycarbonate film or sheet; an olefin film or sheet such as PE (polyethylene) or PP (polypropylene) film or sheet; A polyetheretherketone (PEEK) film or sheet, a polyetherimide (PEI) film or sheet, a polyethylenenaphthatate (PEN) film or sheet, a polyester film such as a PET (polyethyleneterephtalate) film or sheet, A polysulfone film or sheet, a PAR (polyarylate) film or sheet, a fluororesin film or sheet, and the like, and generally a cellulose film or sheet, a polyester film, A sheet or an acrylic film or sheet can be used, and preferably a TAC film or sheet can be used However, it can be appropriately selected in consideration of the object of the present application.

As the electrode layer, a transparent conductive layer may be used. 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 ITO (Indium Tin Oxide). In one embodiment, indium tin oxide (ITO) may be used for the electrode layer.

The resin layers 120 and 320 may include a resin. Specifically, the resin may include all resins known in the art, and may preferably include a curable resin. More preferably, it may include a photo-curable resin. The photocurable resin means a resin that is cured by ultraviolet rays, and may include an acrylate-based functional group. For example, a reactive acrylate oligomer, a multifunctional acrylate monomer, or a mixture thereof may be used as the photocurable resin. In one example, the reactive acrylate oligomer includes a urethane acrylate oligomer, an epoxy acrylate oligomer, a polyester acrylate, a polyether acrylate, Or a mixture thereof.

Examples of the polyfunctional acrylate monomer include dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, trimethylene propyl triacrylate, propoxylated glycerol triacrylate, trimethylpropaneethoxy triacrylate, 1,6-hexanediol diacrylate, propoxylated glycerol tri Propoxylated glycerol triacrylate, tripropylene glycol diacrylate, ethylene glycol diacrylate, or a mixture thereof may be used.

The resin may include a photo-alignment resin. As used herein, the term "photo-orientable resin" may mean, for example, a compound which is oriented by a photo-isomerization reaction by photoirradiation, a photo-degradation reaction, or a photo-dimerization reaction and exhibits liquid crystal alignability. For example, the photo-orientable resin may be a resin exhibiting liquid crystal alignability through a photo-dimer reaction by polarized ultraviolet irradiation.

As used herein, the term " liquid crystal alignability " may mean a property capable of orienting a liquid crystal molecule, a liquid crystal compound, or a precursor thereof adjacent to an alignment film, a photo-alignment resin or a reactant of the resin in a predetermined direction.

The photo-orientable resin may be a resin widely known in the art, but is not limited thereto. As the photo-orientable resin, for example, at least one selected from the group consisting of polyamide, polyimide, polyvinyl alcohol, polyamic acid and polyninnamate can be used.

In one example, when the beads 101 are fixed by the alignment films 130 and 330, they may be dispersed in the alignment films 130 and 330. For example, the beads 101 may be contained in the alignment layers 130 and 330 in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the orienting resin, and specifically 0.1 to 10 parts by weight, 5 parts by weight or 0.1 part by weight to 3 parts by weight. The first substrate 100 and / or the second substrate 300 may be provided with an excellent surface roughness (i.e., an excellent surface roughness) in a state including the alignment films 130 and 330 by including the beads 101 in the alignment films 130 and 330 within the above- Thereby improving the scattering mode delay phenomenon that occurs partially in the voltage application for switching the liquid crystal cell from the transmissive mode to the scattering mode.

In another example, when the beads 101 are fixed by the resin layers 120 and 320 and the alignment films 130 and 330, the resin layers 120 and 320 and the alignment films 130 and 330, Lt; / RTI > Specifically, the beads 101 may be contained in the resin layers 120 and 320 in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the resin, specifically 0.1 to 10 parts by weight, 0.1 to 5 parts by weight, Or 1 part by weight to 3 parts by weight. The first substrate 100 and / or the second substrate 300 can have excellent surface roughness in a state including the alignment films 130 and 330 by including the beads 101 in the resin layer within the above-described range , Thereby improving the scattering mode delay phenomenon that occurs partially in the voltage application for switching the liquid crystal cell from the transmission mode to the scattering mode.

As the kind of the beads 101, at least one particle selected from the group consisting of a polymer system, a carbon system, a metal system, a composite system, and an oxide system can be used and can be appropriately selected and used in view of the object of the present application. In one example, the beads 101 may be made of one or more particles made of a polymer system, and specifically, polystyrene (PS), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC) Butadiene, polystyrene-co-acrylonitrile (SAN), polyvinylidene chloride-co-vinyl chloride), polyurethane and polyvinylidene fluoride (PVDF) And one or more particles selected from the group consisting of polymethylmethacrylate may be used, and polymethylmethacrylate may preferably be used.

In one example, the alignment film 130, 330 may be a vertical alignment film, in order to realize a normally transmissive mode. As the alignment layers 130 and 330, an alignment layer having a vertically aligning ability with respect to an adjacent liquid crystal layer can be used without any particular limitation. For example, an alignment film known to be capable of exhibiting alignment characteristics by a non-contact method such as irradiation of linear polarized light including a contact alignment film or a photo alignment film compound such as a rubbing alignment film can be used.

The liquid crystal layer 200 may include a non-reactive liquid crystal. The non-reactive liquid crystal in the liquid crystal layer 200 can perform a function of varying the transmittance by changing the orientation according to an external action, for example, whether an external voltage is applied. Any kind of liquid crystal compound can be used as the non-reactive liquid crystal so long as the alignment direction can be changed by application of an external action. For example, the liquid crystal compound may be a smectic liquid crystal compound, a nematic liquid crystal compound, or a cholesteric liquid crystal compound. Further, the liquid crystal compound may be a compound which does not have a polymerizable group or a crosslinkable group, for example, so that the orientation direction can be changed by application of an external action.

In one example, the nonreactive liquid crystal may have a negative dielectric anisotropy. In this specification, the term "dielectric anisotropy (Δε)" can mean the difference (ε // - ε ㅗ) between the horizontal permittivity (ε //) and the vertical permittivity (ε ㅗ) of the liquid crystal. The term "horizontal permittivity (ε //)" as used herein means a permittivity value measured along the direction of the electric field in a state where a voltage is applied so that the direction of the electric field due to the director and the applied voltage of the liquid crystal molecule is substantially horizontal Refers to a dielectric constant measured along the direction of the electric field in a state where a voltage is applied so that the direction of the electric field due to the director and the applied voltage of the liquid crystal molecule is substantially perpendicular.

In one example, the absolute value of the dielectric anisotropy ([Delta] [epsilon]) of the non-reactive liquid crystal may be within a range of, for example, about 1 to 20. The lower limit of the absolute value of the dielectric anisotropy (DELTA epsilon) of the non-reactive liquid crystal may be at least 1, at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, or at least 9, The upper limit of the absolute value of the dielectric anisotropy (? Epsilon) of the dielectric anisotropy?? Can 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 non-reactive liquid crystal satisfies the above range, the liquid crystal cell can be driven with a low driving voltage, exhibits excellent haze characteristics, and can realize a liquid crystal cell switching between a transparent mode and a scattering mode Do.

In one example, the refractive index anisotropy of the non-reactive liquid crystal can be appropriately selected in consideration of the objective properties, for example, the haze characteristics of the liquid crystal cell. As used herein, the term " refractive index anisotropy " may mean a difference between an ordinary refractive index and an extraordinary refractive index of a non-reactive liquid crystal. The extraordinary refractive index means a refractive index with respect to the optical axis of the non-reactive liquid crystal, and the normal refractive index can mean a refractive index with respect to a direction perpendicular to the optical axis of the non-reactive liquid crystal. The refractive index anisotropy of the liquid crystal compound may be in the range of, for example, 0.1 or more, 0.12 or more or 0.15 or more to 0.23 or less or 0.25 or less or 0.3 or less. When the refractive index anisotropy of the non-reactive liquid crystal satisfies the above range, for example, a normal transmission mode device having excellent haze characteristics can be realized. The term " optical axis " in the present specification may mean an axis in the long axis direction of the liquid crystal when the liquid crystal has a rod shape, and may mean an axis in the normal direction of the plane of the original plate when the liquid crystal has a discotic shape. have.

The liquid crystal layer 200 may further include a conductivity adjusting agent. According to an embodiment of the present invention, the liquid crystal layer 200 may be a liquid crystal layer driven in a dynamic scattering mode. The dynamic scattering mode may refer to a liquid crystal mode that causes electrohydrodynamic instability (EHDI). Generally, the dynamic scattering mode liquid crystal layer includes non-reactive liquid crystals in a nematic or smectic phase and a conductivity adjuster for inducing EHDI. When an electric field is applied to the liquid crystal layer 200, convection occurs due to EHDI, As a result, a new convection structure is formed, which ultimately changes to a turbulent flow, which causes strong scattering of light for optical anisotropy and fluid motion of the liquid crystal.

The conductivity modifier for inducing EHDI may include, for example, one or more selected from an anisotropic dye, a reactive monomer, and an ionic compound. In one example, the liquid crystal cell may include an anisotropic dye, a reactive liquid crystal, and an ionic compound as a conductivity adjusting agent in the liquid crystal layer 200.

The anisotropic dye improves the light shielding ratio of the liquid crystal cell and can contribute to varying the transmittance. As used herein, the term " dye " may refer to a material that is capable of intensively absorbing and / or modifying light within a visible light region, for example, within a wavelength range of 400 nm to 700 nm, at least partially or entirely. Further, in this specification, the term " anisotropic dye " may mean a material capable of anisotropic absorption of light in at least a part or the entire range of the visible light region. As the anisotropic dye, for example, a known dye known to have a property of being aligned according to the alignment state of the liquid crystal can be selected and used. For example, a black dye can be used. As such a dye, for example, an azo dye or an anthraquinone dye can be used.

When the anisotropic dye is included in the liquid crystal layer 200, the anisotropic dye may be included in an amount of 0.1 to 2.0 parts by weight based on 100 parts by weight of the non-reactive liquid crystal. Specifically, the anisotropic dye may be contained in an amount of 0.5 to 2.0 parts by weight, 1.0 to 2.0 parts by weight, 1.0 to 1.8 parts by weight or 1.0 to 1.5 parts by weight based on 100 parts by weight of the non-reactive liquid crystal have. By including anisotropic dyes in the liquid crystal layer 200 within the above-described range, it is possible to improve the light shielding ratio of the liquid crystal cell, thereby contributing to varying the transmittance.

As the reactive monomer, a reactive mesogen having good mixing property with liquid crystal can be used. As used herein, the reactive mesogen may refer to a compound that contains moieties capable of exhibiting liquid crystallinity, for example, a mesogen skeleton, and also includes at least one reactive functional group. As the reactive functional group, for example, a polymerizable functional group or a crosslinkable functional group can be exemplified. Examples of the reactive group include an acryloyl group, an acryloyloxy group, a methacryloyl group, a methacryloyloxy group, a carboxyl group, a hydroxy group, a vinyl group, and an epoxy group, but not limited thereto, May be included. The reactive mesogens may comprise polyfunctional reactive mesogens or monofunctional reactive mesogens. As used herein, the term " polyfunctional reactive mesogens " may refer to compounds containing two or more reactive functional groups in the mesogens. In one example, the polyfunctional reactive mesogen comprises 2 to 10, 2 to 8, 2 to 6, 2 to 5, 2 to 4, 2 to 3 or 2 reactive functional groups Can be included. In addition, the term " monofunctional reactive mesogens " may refer to compounds containing one reactive functional group in the mesogens.

When the reactive monomer is contained in the liquid crystal layer 200, the reactive monomer may be contained in an amount of 1 to 20 parts by weight based on 100 parts by weight of the non-reactive liquid crystal. Specifically, the reactive monomer may be contained in an amount of 3 to 18 parts by weight, 3 to 13 parts by weight or 3 to 12 parts by weight based on 100 parts by weight of the non-reactive liquid crystal. By including the reactive monomer in the liquid crystal layer 200 within the above-described range, it is possible to form a liquid crystal layer having excellent physical properties while effectively ensuring conductivity.

In the present specification, an ionic compound may mean a salt-type compound in which ions having opposite charges, for example, cation and anion are formed by ionic bonding. The ionic compound may be electrically neutral. Examples of such ionic compounds include, but are not limited to, a nitrogen-containing onium salt, a sulfur-containing onium salt, or a phosphorus-containing onium salt. Specifically, the ionic compound may be an ionic impurity, an ionic liquid, or a salt. For example, the ionic impurities include 2,2,6,6-Tetramethylpiperidine-1- Oxyl Free radical can be used and TMAPF ₆ or BMIN-BF ₄ (1-butyl-3-methylimidazolium BF ₄ ) can be used as the ionic liquid. CTAB (Cetrimonium bromide), CTAI (Cetrimonium Iodide), and CTAI ₃ (Cetrimonium triiodide).

When the ionic compound is contained in the liquid crystal layer 200, the ionic compound may be contained in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the non-reactive liquid crystal. Specifically, the ionic compound is contained in a ratio of 0.1 to 1.5 parts by weight, 0.1 to 1.2 parts by weight, 0.1 to 1.0 parts by weight, or 0.1 to 0.5 parts by weight based on 100 parts by weight of the non-reactive liquid crystal . By including an ionic compound in the liquid crystal layer 200 within the above-described range, the conductivity of the liquid crystal layer can be effectively ensured. The ionic compound contains a small amount of the above-mentioned range in consideration of solubility in the liquid crystal compound can do.

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

The term " scattering mode " means a mode in which a liquid crystal cell exhibits haze over a predetermined level, and the term " transmissive mode " means a mode in which light is transmissive or a mode exhibiting haze below a predetermined level .

For example, in the scattering mode, the liquid crystal cell may have 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, , 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, for example, the liquid crystal cell may have a haze of less than 10%, less than 8%, less than 6%, or less than 5%.

The haze may be a percentage of the transmittance of the diffused light to the transmittance of the total transmitted light passing through the object to be measured. The haze can be evaluated using a hazemeter (NDH-5000SP). The haze can be evaluated in the following manner using the haze meter. That is, light is transmitted through the object to be measured and is incident into the integrating sphere. In this process, light is separated into diffused light (DT) and parallel light (PT) by the object to be measured. The light is reflected in the integrating sphere and condensed on the light receiving element, and the haze can be measured through the condensed light Do. That is, the total transmitted light TT according to the above procedure is the sum (DT + PT) of the diffused light DT and the parallel light PT and the haze is the percentage of diffused light with respect to the total transmitted light (Haze (%) = 100 X DT / TT).

The liquid crystal cell may be in a transparent mode in a state in which no external action is applied, and may be switched to a scatter mode in the case where external action is applied. The liquid crystal layer 200 may exist in a vertically aligned state in a state where no external action is applied to the liquid crystal cell. When a voltage is applied to the liquid crystal layer 200 to realize a scattering mode, it may take a certain time until the region where the scattering mode is not observed disappears. A relatively low voltage is applied to the region of the liquid crystal layer away from the electrode layer, and a scattering mode delay phenomenon occurs. The area in which the scattering mode is not expressed can be visually recognized as a stain during driving, and the time until the area where the scattering mode is not visible disappears can be referred to as a driving stain retention time. The liquid crystal cell of the present application can reduce the driving unevenness time by adjusting the surface roughness of the first substrate 100 and / or the second substrate 300 including the alignment layers 120 and 320.

In one example, when applying a voltage of 30 V, the liquid crystal layer 200 may have a time of less than 25 seconds to implement the scattering mode. Specifically, when the voltage of 30 V is applied to the liquid crystal layer 200, the time for implementing the scattering mode may be 24 seconds or less, 23 seconds or less, 22 seconds or less, or 21 seconds or less. The shorter the driving unevenness holding time, the better the driving characteristic. The lower limit of the driving uneven holding time is not particularly limited, but may be generally 10 seconds or more, 13 seconds or 15 seconds or more.

In another example, when the liquid crystal layer 200 is applied with a voltage of 35 V, the time for implementing the scattering mode may be less than 11 seconds. Specifically, when the voltage of 30 V is applied to the liquid crystal layer 200, the time for implementing the scattering mode may be 10 seconds or less, 9 seconds or less, or 8 seconds or less. The shorter the driving non-uniformity holding time, the better the driving characteristic. The lower limit of the driving non-uniform holding time is not particularly limited, but may be generally 5 seconds or more, 6 seconds or more or 7 seconds or more.

In another example, when the liquid crystal layer 200 is applied with a voltage of 40 V, the time for implementing the scattering mode may be less than 8 seconds. Specifically, when the voltage of 40 V is applied to the liquid crystal layer 200, the time for implementing the scattering mode may be 7 seconds or less, 6 seconds or less, or 5 seconds or less. The shorter the driving non-uniformity holding time is, the better the driving characteristic is. The lower limit of the driving non-uniform holding time is not particularly limited, but may be generally 2 seconds or more, 3 seconds or 4 seconds or more.

The present application also relates to the use of a liquid crystal cell. The exemplary liquid crystal cell is excellent in the transmittance in the initial transmission mode and the transmittance in the scattering mode when voltage is applied, and can exhibit excellent haze in the scattering mode. Such a liquid crystal cell can be applied to various optical modulation devices such as a smart window, a window protective film, a flexible display device, a transparent display shading plate, an active retarder for 3D image display, or a viewing angle adjusting film.

The present application can provide a liquid crystal cell in which a scattering mode delay phenomenon partially occurring when a voltage for switching from a transmission mode to a scattering mode is improved, and a use thereof is provided. Such a liquid crystal cell can be applied to various optical modulation devices such as a smart window, a window protective film, a flexible display device, a transparent display shading plate, an active retarder for 3D image display, or a viewing angle adjusting film.

Figs. 1 to 4 respectively illustrate a liquid crystal cell according to an embodiment of the present application.
5 to 7 are microscope images (X 200) taken after coating the first alignment layer or the second alignment layer of the first substrate manufactured in Examples 1 and 2 and Comparative Example, respectively.

The present application will be specifically described by way of the following examples, but the scope of the present application is not limited by the following examples.

Example  One

Preparation of alignment film composition

100 g of the composition for vertical alignment film (SE-5661, Nissan) and 0.1 g of beads having a diameter of 370 nm (XX-128BQ, manufactured by SEKISUI) were mixed to prepare an alignment film composition.

1st  Fabrication of Substrate

The alignment film composition prepared above was coated on ITO (Indium Tin Oxide) film to a thickness of 250 nm using a mayer bar (# 4). A first substrate was prepared by drying the coated alignment film composition at about 130 캜 for about 5 minutes.

Second  Fabrication of Substrate

The alignment film composition prepared above was coated on ITO (Indium Tin Oxide) film to a thickness of 250 nm using a mayer bar (# 4). A second substrate was prepared by drying the coated alignment film composition at about 130 캜 for about 5 minutes.

The liquid crystal cell  Produce

Liquid crystal compounds (HNG730600-200, HCCH), anisotropic dyes (X12, Basf), reactive liquid crystals (HCM-009, HCCH) and cetyltrimethylammonium bromide (CTAB) having a refractive index anisotropy of 0.15 and a dielectric anisotropy of -5.0 (HNG730600-200: X12: HCM-009: CTAB) having a weight ratio of 89.0: 1.0: 10: 0.1 was applied on the alignment layer of the first substrate prepared above, The second substrate was laminated with the alignment layer of the substrate so as to be in contact with the liquid crystal layer to form a liquid crystal layer having a thickness of 10 mu m to produce a liquid crystal cell as shown in Fig.

Example  2

2, in the same manner as in Example 1, except that beads were not included on the ITO film and the orientation film composition prepared in the same manner as in the orientation film composition was applied during the production of the second substrate, Respectively.

Example  3

Preparation of Composition for Resin Layer

0.1 g of polymethyl methacrylate (XX-128BQ, manufactured by SEKISUI), 2 g of acrylate (1,6-hexanediol acrylate), and 2 g of initiator (Irgacure 184 (trade name)) as a bead having a diameter of 370 nm in 100 g of a solvent (cyclohexanone) ) Were mixed to prepare a composition for a resin layer.

1st  Fabrication of Substrate

The composition for the resin layer prepared above was coated on ITO (Indium Tin Oxide) film to a thickness of 100 nm using a mayer bar (# 3). The coated composition was dried at about 100 < 0 > C for about 2 minutes. Then, the dried composition was irradiated with ultraviolet rays of about 200 mW / cm ² intensity for 10 seconds to form a resin layer in which a part of the beads were adhered on the ITO film.

A vertical alignment layer composition (SE-5661, Nissan) was coated to a thickness of 150 nm using a mayer bar (# 4) on the resin layer prepared above, and a microscope image taken was shown in FIG. A first substrate was prepared by drying the coated alignment film composition at about 130 캜 for about 5 minutes.

Second  Fabrication of Substrate

The composition for the resin layer prepared above was coated on ITO (Indium Tin Oxide) film to a thickness of 100 nm using a mayer bar (# 3). The coated composition was dried at about 100 < 0 > C for about 2 minutes. Then, the dried composition was irradiated with ultraviolet rays of about 200 mW / cm ² intensity for 10 seconds to form a resin layer in which a part of the beads were adhered on the ITO film.

A vertical alignment layer composition (SE-5661, Nissan) was coated to a thickness of 150 nm using a mayer bar (# 4) on the resin layer prepared above. A second substrate was prepared by drying the coated alignment film composition at about 130 캜 for about 5 minutes.

The liquid crystal cell  Produce

Liquid crystal compounds (HNG730600-200, HCCH), anisotropic dyes (X12, Basf), reactive liquid crystals (HCM-009, HCCH) and cetyltrimethylammonium bromide (CTAB) having a refractive index anisotropy of 0.15 and a dielectric anisotropy of -5.0 (HNG730600-200: X12: HCM-009: CTAB) having a weight ratio of 89.0: 1.0: 10: 0.1 was applied on the alignment layer of the first substrate prepared above, The liquid crystal cell was fabricated as shown in Fig. 3 by laminating the second substrate so that the alignment layer of the substrate was in contact with the liquid crystal layer.

Example  4

A liquid crystal cell was prepared as shown in Fig. 3 in the same manner as in Example 3, except that the diameter of the beads was changed to 500 nm in the preparation of the resin layer composition. 6 shows a microscope image of a first substrate coated with 150 nm thick vertical alignment layer composition (SE-5661, Nissan) using a mayer bar (# 4) on the resin layer prepared above .

Example  5

In the same manner as in Example 3 except that the composition for the resin layer was applied on the ITO film in the same manner as the composition for the resin layer without containing the beads, To prepare a liquid crystal cell.

Comparative Example

A liquid crystal cell was prepared in the same manner as in Example 1 except that beads were not included on the ITO film and the composition for the resin layer prepared in the same manner as the composition for the resin layer was applied to each of the first and second substrates .

Evaluation example  1. Surface roughness evaluation

The surface roughness (Ra) of the first substrate of the liquid crystal cell manufactured in Examples and Comparative Examples was measured in an area of 10 mu m x 10 mu m using an AFM (NX10, Park systems, Ltd.) Are shown in Table 1 below

Evaluation example  2. Scattering according to driving voltage application Mode is  Evaluate time to be expressed

The liquid crystal cell manufactured in Examples and Comparative Examples was horizontally aligned when a low voltage of about 10 V was applied in a vertically aligned state and the transmittance was decreased. When the voltage was further increased, a scattering mode was developed, And when the voltage was about 30 V to 40 V, a region where the scattering mode was expressed late was generated and observed visually. The voltage was applied to the liquid crystal cell manufactured in the examples and the comparative example to apply voltages of 30 V, 35 V, and 40 V, respectively, to measure the time until the area where the scattering mode was not observed disappears when the scattering mode is implemented, The stain retention time was defined as the retention time, and the results are shown in Table 1 below.

Surface roughness (nm) Driving stain retention time (s) 30 V 35 V 40 V Example 1 34.2 22 8 5 Example 2 34.2 22 9 5 Example 3 35.0 21 8 5 Example 4 42.7 15 7 4 Example 5 35.0 22 9 5 Comparative Example 7.4 25 11 8

As shown in Table 1, in the case of the liquid crystal cell manufactured in Examples 1 to 5 including the alignment film in the first substrate or the bead in which a part was fixed by the alignment layer and the alignment film, The surface roughness value of the first substrate is larger than that of the liquid crystal cell manufactured in the comparative example which does not include the first substrate. Particularly, in the case of the liquid crystal cell manufactured in Example 4, the diameter of the bead to which a part was fixed by the resin layer and the alignment layer was larger than that of the liquid crystal cell manufactured in Example 3, .

In the case of the liquid crystal cell manufactured in Examples 1 to 5, in which the surface roughness value of the first substrate is large, compared to the liquid crystal cell produced in the comparative example in which the surface roughness value of the first substrate is relatively small, And the time was measured to be small. Particularly, in the case of the liquid crystal cell manufactured in Example 4, the surface roughness value of the first substrate was larger than that of the liquid crystal cell manufactured in Example 3, and it was confirmed that the driving stain retention time according to each voltage was measured to be small .

100: first substrate
110, 310: electrode film
120, 320: resin layer
101: Bead
130, 330: alignment film
200: liquid crystal layer
300: second substrate

Claims (15)

A first substrate, a liquid crystal layer, and a second substrate, wherein the liquid crystal layer switches a transmission mode and a scattering mode depending on whether a voltage is applied, and wherein the first substrate and / And a surface roughness of 30 nm or more. The liquid crystal cell according to claim 1, wherein the first substrate and / or the second substrate having a surface roughness of 30 nm or more includes an electrode film and an alignment film, and further comprises a bead to which a part is fixed by the alignment film. The method according to claim 1, wherein the first substrate and / or the second substrate having a surface roughness of 30 nm or more includes an electrode film, a resin layer, and an alignment film, wherein the resin layer and the bead, Further comprising a liquid crystal cell. The liquid crystal cell according to claim 2, wherein the thickness of the alignment layer is from 30 nm to 250 nm. The liquid crystal cell according to claim 4, wherein the diameter of the beads is 50 nm to 500 nm. The liquid crystal cell according to claim 3, wherein the sum of the thicknesses of the alignment layer and the resin layer is 60 nm to 400 nm. The liquid crystal cell according to claim 6, wherein the diameter of the beads is 80 nm to 700 nm. The liquid crystal cell according to claim 1, wherein the first substrate and / or the second substrate has a surface roughness of 100 nm or less in a state including an alignment film. The liquid crystal cell according to claim 1, wherein the thickness of the liquid crystal layer is 3 占 퐉 to 20 占 퐉. The liquid crystal cell according to claim 1, wherein the liquid crystal layer comprises a non-reactive liquid crystal and a conductivity adjusting agent. The liquid crystal cell according to claim 10, wherein the nonreactive liquid crystal has negative dielectric anisotropy. 11. The liquid crystal cell according to claim 10, wherein the conductivity adjusting agent comprises at least one selected from an anisotropic dye, a reactive liquid crystal, and an ionic compound. The liquid crystal cell according to claim 1, wherein the liquid crystal layer implements a transmission mode in an initial state and implements a scattering mode when a voltage is applied. The liquid crystal display device according to claim 1, wherein the liquid crystal layer has a driving stain retention time of less than 25 seconds when a voltage of 30 V is applied, and the driving stain retention time refers to a time until a region in which a scattering mode is not present disappears. Cell. A light modulation device comprising the liquid crystal cell of claim 1.

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