KR20210076532A - Liquid crystal cell - Google Patents

Abstract

This application relates to a liquid crystal cell and a use of the liquid crystal cell. The present application can provide the liquid crystal cell in which a cell gap is properly maintained, and which is advantageous for realization as a flexible device due to excellent adhesion between upper and lower substrates and easily control a desired initial orientation mode. Such the liquid crystal cell may be applied to various optical modulation devices such as smart windows, window protection films, flexible display devices, active retarders for 3D image display, or viewing angle control films.

Description

Liquid crystal cell {LIQUID CRYSTAL CELL}

This application relates to a liquid crystal cell.

For long-term stability and large-area scalability of a liquid crystal film cell using a flexible substrate, it is important to maintain a cell gap between the upper and lower substrates and to provide adhesion between the upper and lower substrates.

Non-Patent Document 1 discloses a technique of forming an organic film pattern in the form of a column or wall having a cell gap height on one substrate and fixing it to the opposite substrate using an adhesive. However, in this technology, the adhesive must be located only on the column or wall surface, and the technology of micro-stamping the adhesive on the column surface or wall has high process difficulty, difficult to control the thickness and area of the adhesive, and the adhesive is difficult to use when bonding the upper and lower substrates. It is highly likely to be pushed out, and there is a risk that the adhesive may be contaminated into the alignment layer or liquid crystal.

“Tight Bonding of Two Plastic Substrates for Flexible LCDs,” SID Symposium Digest, 38, pp. 653-656 (2007)

The present application provides a liquid crystal cell and use of the liquid crystal cell in which the cell gap is properly maintained and the flexible device is implemented as a flexible device due to excellent adhesion between the upper substrate and the lower substrate, and the desired initial alignment mode can be easily adjusted.

This application relates to a liquid crystal cell. 1 and 2 each exemplarily shows a liquid crystal cell of the present application. The liquid crystal cell of the present application may include an upper substrate including an upper substrate film 101 and an optically transparent adhesive layer 200 on one surface of the upper substrate film 101 . The liquid crystal cell of the present application may include a liquid crystal layer 300 including a liquid crystal compound 301 . The liquid crystal cell of the present application may include a lower substrate including a lower substrate film 102 and a horizontal alignment layer 400 on one surface of the lower substrate film 102 . The liquid crystal cell of the present application may sequentially include the upper substrate, the liquid crystal layer, and the lower substrate.

According to the present application, by using an optically clear adhesive layer (OCA layer) instead of a conventional vertical alignment film or horizontal alignment film on the upper substrate, the cell gap of the liquid crystal cell is properly maintained and excellent between the upper substrate and the lower substrate substrate A desired initial alignment mode may be realized by applying an optically transparent adhesive layer having a predetermined surface energy as well as exhibiting adhesive force.

The optically transparent adhesive layer may be a liquid crystal aligning adhesive layer. According to the first embodiment of the present application, the optically transparent adhesive layer may be a horizontally oriented adhesive layer. According to the second embodiment of the present application, the optically transparent adhesive layer may be a vertically oriented adhesive layer. In this specification, when the first embodiment and the second embodiment are described without distinction, the description may be commonly applied to the first embodiment and the second embodiment.

The upper substrate and the lower substrate may be attached to each other by the adhesive force of the optically transparent adhesive layer. In the present specification, the optically transparent adhesive may refer to an adhesive having an average transmittance of about 80% or more, 85% or more, 90% or more, or 95% or more for a visible light region, for example, a wavelength of 380 nm to 780 nm.

The type of the optically clear adhesive is not particularly limited and may be appropriately selected depending on the intended use, for example, a solid adhesive, a semi-solid adhesive, an elastic adhesive, or a liquid crystal adhesive may be appropriately selected and used. The solid adhesive, semi-solid adhesive or elastic adhesive may be referred to as a so-called pressure sensitive adhesive (PSA), and may be cured before an adhesive object is cemented. The liquid adhesive may be referred to as so-called optical clear resin (OCR), and may be cured after the bonding object is cemented.

According to the first embodiment of the present application, the optically transparent adhesive layer may be a horizontally oriented adhesive layer. In the present specification, the “horizontal alignment adhesive layer” may refer to a layer of an adhesive having an adhesive force capable of adhering the upper substrate and the lower substrate while imparting a horizontal alignment force to the liquid crystal compound present in the adjacent liquid crystal layer. have.

According to the first embodiment of the present application, the surface energy of the optically transparent adhesive layer may be 19 mN/m or more. When the surface energy of the optically transparent adhesive layer is within the above range, the horizontal alignment force may be effectively exhibited with respect to the liquid crystal compound present in the adjacent liquid crystal layer. The upper limit of the surface energy of the optically transparent adhesive layer may be, for example, 50 mN/m or less. As the optically transparent adhesive having a surface energy satisfying the above range, for example, an acrylic adhesive layer, an adhesive layer including a mixture of an acrylic material and a silicone material, and a silicone adhesive having a high surface energy may be used.

1 exemplarily shows a liquid crystal cell according to a first embodiment of the present application. According to the first embodiment of the present application, in a state in which no voltage is applied to the liquid crystal layer 300 , the liquid crystal compound 301 may exist in a horizontally aligned state. In the present specification, a state to which no voltage is applied may be referred to as an initial state. The liquid crystal cell of the first embodiment may be referred to as an initial horizontally aligned liquid crystal cell.

In the present specification, the “horizontal alignment state” refers to a state in which the directors of all liquid crystal compounds in the liquid crystal layer are arranged substantially parallel to the plane of the liquid crystal layer, and for example, the angle formed by the directors with respect to the plane of the liquid crystal layer is , for example, in the range of about -10 degrees to 10 degrees or -5 degrees to 5 degrees, or about 0 degrees.

In the present specification, the liquid crystal molecule or the director of the liquid crystal compound may refer to an optical axis or a slow axis of the liquid crystal layer. The director of the liquid crystal molecules may mean a long axis direction when the liquid crystal molecules have a rod shape, and may mean an axis in a normal direction to the plane of the disk when the liquid crystal molecules have a discotic shape. When a plurality of liquid crystal compounds having different directors exist in the liquid crystal layer, the director is a vector sum.

In the present specification, the horizontal orientation state may mean including a planar orientation state and a horizontal twist orientation.

In the present specification, "planar alignment state" may mean an alignment state in which projections of the directors of all liquid crystal compounds in the liquid crystal layer onto the liquid crystal layer plane are parallel to each other.

In the present specification, the “twisted alignment state” may refer to a spiral structure in which the directors of liquid crystal compounds are oriented in layers while twisting along an imaginary spiral axis in the liquid crystal layer. The twist alignment state may be implemented in a vertical, horizontal or oblique alignment state, that is, the vertical twist alignment state is a state in which individual liquid crystal compounds are twisted along a spiral axis in a vertically aligned state to form a layer, and the horizontal twist alignment state The state is a state in which individual liquid crystal compounds are horizontally aligned and twisted along the spiral axis to form layers, and the oblique twist alignment state is a state in which individual liquid crystal compounds are aligned and twisted along the spiral axis to form layers.

According to the first embodiment of the present application, in a state in which no voltage is applied, the tilt angle on the horizontal alignment layer surface of the liquid crystal layer and the tilt angle on the optically transparent adhesive layer surface may be 10 degrees or less, respectively. In the present specification, the tilt angle may mean an angle formed by a director of a liquid crystal compound with respect to a plane parallel to the alignment layer or the adhesive layer.

According to the first embodiment of the present application, in a state in which no voltage is applied, the thickness direction retardation of the liquid crystal layer with respect to a wavelength of 550 nm may be less than 50 nm.

In the present specification, the thickness direction retardation Rth may mean a value calculated by Equation A below.

[Formula A]

Rth = d × (nz - ny)

In Equation A, Rth is the thickness direction retardation (nm), d is the thickness of the liquid crystal layer, ny is the refractive index in the fast axis direction of the liquid crystal layer, and nz is the refractive index in the thickness direction of the liquid crystal layer.

According to the second embodiment of the present application, the optically transparent adhesive may be a vertically oriented adhesive. In the present specification, "vertically oriented adhesive layer" refers to a layer including an adhesive that provides vertical alignment force to the liquid crystal compound present in the adjacent liquid crystal layer and has adhesive force capable of adhering the upper substrate and the lower substrate at the same time. can do.

According to the second embodiment of the present application, the surface energy of the optically transparent adhesive layer may be 16 mN/m or less. When the surface energy of the optically transparent adhesive layer is within the above range, the vertical alignment force may be effectively exhibited with respect to the liquid crystal compound present in the adjacent liquid crystal layer. The lower limit of the surface energy of the optically transparent adhesive layer may be, for example, 5 mN/m or more.

As an optically transparent adhesive whose surface energy satisfies the above range, for example, a silicone-based adhesive may be used. The silicone-based adhesive may be a cured product of a composition including a curable silicone compound.

The type of the curable silicone compound is not particularly limited, and, for example, a heat-curable silicone compound or an ultraviolet-curable silicone compound may be used.

In one example, the curable silicone compound may be an addition curable silicone compound.

Specifically, the addition-curable silicone compound may be exemplified by (1) an organopolysiloxane containing two or more alkenyl groups in a molecule and (2) an organopolysiloxane containing two or more silicon-bonded hydrogen atoms in a molecule. However, the present invention is not limited thereto. The silicone compound as described above can form a cured product by addition reaction, for example, in the presence of a catalyst to be described later.

More specific examples of the (1) organopolysiloxane that can be used in the present application include a dimethylsiloxane-methylvinylsiloxane copolymer blocking trimethylsiloxane groups at both ends of the molecular chain, methylvinylpolysiloxane blocking both ends of the molecular chain, methylvinylpolysiloxane, and molecular chain Blocking trimethylsiloxane groups at both ends Dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer, blocking dimethylvinylsiloxane groups at both ends of the molecular chain Dimethylpolysiloxane, blocking dimethylvinylsiloxane groups at both ends of the molecular chain Methylvinylpolysiloxane, dimethylvinylsilox at both ends of the molecular chain acid groups blocked dimethylsiloxane-methylvinylsiloxane copolymer, a molecular chain, both ends dimethylvinylsiloxy group blocked dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers, R ^1- ₂ siloxane units and R ¹ ₂ R represented by SiO _1/2 ² Organopolysiloxane copolymer comprising a siloxane unit represented by SiO _1/2 and a siloxane unit represented by SiO _4/2 ^{, R 1} ₂ R ² A siloxane unit represented by SiO _{1/2 and SiO 4/2} An organopolysiloxane copolymer comprising a siloxane unit to be R ₁ R ₂ SiO _2/2 and a siloxane unit represented by R ₁ SiO _3/2 or a siloxane unit represented by R ₂ SiO _3/2 and organopolysiloxane copolymers including, but not limited to, mixtures of two or more of the above.

In the above, R ¹ is a hydrocarbon group other than the alkenyl group, specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or a heptyl group; Aryl groups, such as a phenyl group, a tolyl group, a xylyl group, or a naphthyl group; an aralkyl group such as a benzyl group or a phenentyl group; It may be a halogen-substituted alkyl group such as a chloromethyl group, a 3-chloropropyl group, or a 3,3,3-trifluoropropyl group.

In addition, in the above, R ² is an alkenyl group, and specifically, may be a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, or a heptenyl group.

More specific examples of the organopolysiloxane (2) that can be used in the present invention include methylhydrogenpolysiloxane blocked with trimethylsiloxane groups at both ends of the molecular chain, dimethylsiloxane-methylhydrogen copolymer with both ends of the molecular chain blocked with trimethylsiloxane groups, and molecules Blockade of trimethylsiloxane groups at both ends of the chain dimethylsiloxane-methylhydrogensiloxane-methylphenylsiloxane copolymer, blockade of dimethylhydrogensiloxane groups at both ends of the chain dimethylpolysiloxane, blockade of dimethylhydrogensiloxane groups at both ends of the molecular chain Dimethylsiloxane-methylphenylsiloxane copolymer , methylphenylpolysiloxane with dimethylhydrogensiloxane group blocking at both ends of the molecular chain, ^{a siloxane unit represented by R 1} ₃ SiO _1/2 , a siloxane unit represented by R ¹ ₂ HSiO _1/2 , and a siloxane unit represented by SiO _4/2 An organopolysiloxane copolymer comprising, an organopolysiloxane copolymer comprising a ^{siloxane unit represented by R 1} ₂ HSiO _1/2 and a siloxane unit represented by SiO _4/2 , a siloxane unit represented by R ¹ HSiO _2/2 and an ^{organopolysiloxane copolymer including a siloxane unit represented by and R 1} SiO _3/2 or a siloxane unit represented by HSiO _3/2 , and a mixture of two or more of the above, but is not limited thereto. In the above, R ¹ is a hydrocarbon group other than the alkenyl group, specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or a heptyl group; Aryl groups, such as a phenyl group, a tolyl group, a xylyl group, or a naphthyl group; an aralkyl group such as a benzyl group or a phenentyl group; It may be a halogen-substituted alkyl group such as a chloromethyl group, a 3-chloropropyl group, or a 3,3,3-trifluoropropyl group.

2 exemplarily shows a liquid crystal cell according to a second embodiment of the present application. According to the second embodiment of the present application, in a state in which no voltage is applied to the liquid crystal layer 300 , the liquid crystal compound 301 may exist in a hybrid alignment state. The liquid crystal cell of the second embodiment may be referred to as an initial hybrid alignment liquid crystal cell.

In the present specification, the “hybrid alignment state” may refer to an alignment state in which a tilt angle, which is an angle formed by a director of a liquid crystal compound in the liquid crystal layer with respect to the plane of the liquid crystal layer, gradually increases or decreases along the thickness direction of the liquid crystal layer.

In the present specification, “hybrid orientation state” may mean including hybrid twist orientation. Hybrid twist alignment may refer to an alignment state in which the tilt angle of the liquid crystal compound in the liquid crystal layer is gradually increased or decreased along the thickness direction and is twisted along a helical axis parallel to the thickness direction of the liquid crystal layer to form a layer.

According to the second embodiment of the present application, the tilt angle of the liquid crystal compound adjacent to the horizontal alignment layer of the lower substrate may have a minimum angle and the tilt angle of the liquid crystal compound adjacent to the optically transparent adhesive layer of the upper substrate may have a maximum angle. . In one example, the liquid crystal compound adjacent to the horizontal alignment layer of the lower substrate may exist in a horizontally aligned state, and the liquid crystal compound adjacent to the optically transparent adhesive layer of the upper substrate may exist in a vertically aligned state.

In the present specification, "vertical alignment state" is a state in which the director of the liquid crystal compound in the liquid crystal layer is arranged substantially perpendicular to the plane of the liquid crystal layer, for example, the angle the director makes with respect to the plane of the liquid crystal layer is, for example, For example, it may be in the range of about 80 degrees to 100 degrees or 85 degrees to 95 degrees, or about 90 degrees.

According to the second embodiment of the present application, in a state in which no voltage is applied, the tilt angle of the liquid crystal layer on the horizontal alignment layer surface is 10 degrees or less, and the tilt angle on the optically transparent adhesive layer surface is 80 degrees to 90 degrees May be within range tomorrow.

According to the second embodiment of the present application, in a state in which no voltage is applied, the thickness direction retardation of the liquid crystal layer with respect to a wavelength of 550 nm may be 50 nm or more. The upper limit of the thickness direction retardation with respect to a wavelength of 550 nm of the liquid crystal layer may be, for example, 400 nm or less.

The lower substrate may include a horizontal alignment layer on one surface of the lower substrate film. The horizontal alignment layer and the liquid crystal layer may be in contact with each other. In the present specification, the “horizontal alignment layer” may refer to a layer including an alignment material that imparts horizontal alignment force to a liquid crystal compound present in an adjacent liquid crystal layer. Unlike the optically transparent adhesive layer, the horizontal alignment layer may not have an adhesive force for bonding the upper substrate and the lower substrate. In one example, the peeling force of the horizontal alignment layer to the upper substrate in the state of the liquid crystal cell of FIG. 1 or FIG. 2 may be close to zero.

The horizontal alignment layer may be a rubbing alignment layer or a photo-alignment layer. The alignment direction of the alignment layer may be a rubbing direction in the case of a rubbing alignment layer and a direction of polarized light to be irradiated in the case of a photo-alignment layer. This alignment direction can be confirmed by a detection method using an absorption-type linear polarizer. Specifically, in a state in which the liquid crystal compound included in the transmittance variable layer is horizontally aligned, an absorption-type linear polarizer is disposed on one surface of the transmittance variable layer, and the transmittance is measured while rotating the polarizer 360 degrees, thereby confirming the alignment direction. In the above state, when the luminance (transmittance) is measured from the other side while irradiating light to the transmittance variable layer or the absorption-type linear polarizer, the transmittance tends to be low when the absorption axis or the transmission axis and the alignment direction of the liquid crystal alignment layer coincide The orientation direction can be confirmed through simulation reflecting the refractive index anisotropy of the applied liquid crystal compound. A method of confirming the alignment direction according to the mode of the liquid crystal layer (transmittance variable layer) is known, and in the present application, the alignment direction of the alignment layer can be confirmed in this known method.

As the alignment layer, a polyimide compound, a poly(vinyl alcohol) compound, a poly(amic acid) compound, a polystyrene compound, a polyamide compound, and polyoxyethylene A material known to exhibit alignment ability by rubbing alignment, such as a (polyoxyethylene) compound, or a polyimide compound, a polyamic acid compound, a polynorbornene compound, or a phenylmaleimide copolymer copolymer compound, polyvinylcinnamate compound, polyazobenzene compound, polyethyleneimide compound, polyvinylalcohol compound, polyamide compound, polyethylene compound, polystyrene (polystylene) compound, polyphenylenephthalamide compound, polyester compound, CMPI (chloromethylated polyimide) compound, PVCI (polyvinylcinnamate) compound, polymethyl methacrylate compound, etc. It may include one or more selected from the group consisting of materials known to be capable of exhibiting orientation by the present invention, but is not limited thereto.

The liquid crystal layer may include a liquid crystal compound. As the liquid crystal compound, any kind of liquid crystal compound may be used as long as its alignment direction can be changed by application of an external signal. For example, as the liquid crystal compound, a smectic liquid crystal compound, a nematic liquid crystal compound, or a cholesteric liquid crystal compound may be used. In addition, the liquid crystal compound may be, for example, a compound having no polymerizable group or crosslinkable group so that the orientation direction thereof can be changed by application of an external action. As used herein, the term “external action” may refer to any external factor that may affect the behavior of a material included in the liquid crystal layer, for example, an external voltage. Accordingly, the state in which there is no external action may mean a state in which there is no application of an external voltage or the like.

The liquid crystal layer may include a liquid crystal compound having a positive dielectric anisotropy, or the liquid crystal layer may exhibit the above-mentioned dielectric anisotropy. The absolute value of the dielectric anisotropy may be appropriately selected in consideration of the purpose of the present application. The term “dielectric anisotropy (Δε)” may mean a difference (ε// - ε⊥) between a horizontal dielectric constant (ε//) and a vertical dielectric constant (ε⊥). As used herein, the term horizontal permittivity (ε//) refers to a dielectric constant value measured along the direction of the electric field in a state in which a voltage is applied so that the direction of the electric field by the direction of the liquid crystal molecules and the applied voltage is substantially horizontal, The perpendicular permittivity ε⊥ refers to a dielectric constant value measured along the direction of the electric field in a state in which a voltage is applied so that the direction of the electric field by the applied voltage is substantially perpendicular to the direction of the liquid crystal molecules.

The liquid crystal layer may include a liquid crystal compound having a refractive index anisotropy (Δn) in the range of about 0.05 to 0.1, or the transmittance variable layer may exhibit the above-mentioned refractive index anisotropy. The refractive index anisotropy (Δn) referred to in the present application is a difference (ne-no) between an extraordinary refractive index (ne, extraordinary refractive index) and an ordinary refractive index (no, ordinary refractive index), which can be confirmed using an Abbe refractometer.

The liquid crystal layer may further include a dichroic dye together with the liquid crystal compound in terms of controlling light transmittance variable characteristics. In this case, the liquid crystal layer may be referred to as a guest host liquid crystal layer. As used herein, the term "dye" may mean a material capable of intensively absorbing and/or modifying light within the visible light region, for example, at least a portion or the entire range within the wavelength range of 400 nm to 700 nm, The term “dichroic dye” may refer to a material capable of anisotropic absorption of light in at least a part or the entire range of the visible light region. Such dyes are, for example, known as azo dyes or anthraquinone dyes, but are not limited thereto.

In the present specification, "GHLC layer (Guest host liquid crystal layer)" is a dichroic dye arranged together according to the arrangement of the liquid crystal, and anisotropic light absorption with respect to the alignment direction of the dichroic dye and the direction perpendicular to the alignment direction, respectively It may mean a functional layer exhibiting properties. For example, a dichroic dye is a material whose absorption rate of light varies depending on the polarization direction. If the absorption rate of light polarized in the long-axis direction is large, it is called a p-type dye, and if the absorption rate of light polarized in the short-axis direction is large, it is called an n-type dye. can be called In one example, when a p-type dye is used, polarized light vibrating in the long axis direction of the dye is absorbed, and polarized light vibrating in the short axis direction of the dye is absorbed and transmitted therethrough. Hereinafter, it is assumed that the dichroic dye is a p-type dye, unless otherwise specified.

The ratio of the dichroic dye included in the GHLC layer is not particularly limited, and may be set in an appropriate range in consideration of the desired transmittance. In general, in consideration of the miscibility of the dichroic dye and the liquid crystal compound, the dichroic dye may be included in the liquid crystal layer in an amount of about 0.1 wt% to about 4 wt%.

The liquid crystal cell including the GHLC layer may function as an active polarizer. As used herein, the term “active polarizer” may refer to a functional device capable of controlling anisotropic light absorption according to application of an external signal. Such an active polarizer may be distinguished from a passive polarizer, which will be described later, which has constant light absorption or light reflection characteristics regardless of application of an external signal. The GHLC layer may control anisotropic light absorption with respect to polarization in a direction parallel to the arrangement direction of the dichroic dye and polarization in a direction perpendicular to the arrangement direction of the dichroic dye by controlling the arrangement of the liquid crystal and the dichroic dye. Since the arrangement of the liquid crystal and the dichroic dye can be controlled by the application of an external signal such as a magnetic field or an electric field, the GHLC layer can control the anisotropic light absorption according to the external signal application.

According to the first embodiment of the present application, when the liquid crystal layer further includes a dichroic dye, the liquid crystal cell may exhibit the maximum transmittance from the front when the transmittance is measured according to the viewing angle. The front surface of the liquid crystal cell may mean a direction parallel to the normal direction of the plane of the liquid crystal cell. In one example, the liquid crystal cell may exhibit the maximum transmittance within the range of -10 degrees to 10 degrees based on the normal direction of the plane of the liquid crystal cell when measuring the transmittance according to the viewing angle.

According to the second embodiment of the present application, when the liquid crystal layer further includes a dichroic dye, the liquid crystal cell may exhibit maximum transmittance from the front when transmittance is measured according to a viewing angle. The front surface of the liquid crystal cell may mean a direction parallel to the normal direction of the plane of the liquid crystal cell. In one example, the liquid crystal cell may exhibit the maximum transmittance within the range of 20 to 60 degrees based on the normal direction of the plane of the liquid crystal cell when measuring transmittance according to the viewing angle.

According to the first embodiment of the present application, the liquid crystal compound and/or the dichroic dye included in the liquid crystal layer may exist in a horizontal alignment state when no voltage is applied, and may exist in a vertical alignment state when a voltage is applied. As described above, the horizontal orientation state includes a planar orientation and a horizontal twist orientation. Such a driving mode includes an ECB mode, a twisted nematic (TN) mode, or a super twisted nematic (STN) mode.

According to the second embodiment of the present application, the liquid crystal compound and/or the dichroic dye included in the liquid crystal layer may exist in a hybrid alignment state when no voltage is applied, and may exist in a vertical alignment state when voltage is applied. As described above, the hybrid orientation state includes a twist hybrid orientation state. Such a driving mode includes a hybrid aligned nematic (HAN) mode, a twisted hybrid aligned nematic (HAN) mode, or a super twisted hybrid aligned nematic (HAN) mode.

The liquid crystal layer may further include a chiral agent so that the liquid crystal layer may implement a twisted alignment state. A chiral agent or chiral dopant that may be included in the liquid crystal layer is not particularly limited as long as it can induce a desired twisting without impairing liquid crystallinity, for example, nematic regularity. can be used The chiral agent for inducing rotation in the liquid crystal molecules needs to contain at least chirality in the molecular structure. The chiral agent includes, for example, a compound having one or two or more asymmetric carbons, a compound having an asymmetric point on a heteroatom such as a chiral amine or a chiral sulfoxide, or cumulene ) or a compound having an axially asymmetric, optically active site having an axial agent such as binaphthol may be exemplified. The chiral agent may be, for example, a low molecular weight compound having a molecular weight of 1,500 or less. As the chiral agent, a commercially available chiral nematic liquid crystal, for example, a chiral dopant liquid crystal S-811 commercially available from Merck or LC756 from BASF may be used.

The liquid crystal cell according to the first embodiment or the second embodiment may implement a blocking mode in a state in which an external action is not applied, and may be converted to a transmissive mode by an external action. The light transmittance of the liquid crystal cell in an external action non-applied state may be appropriately adjusted according to the use of the liquid crystal cell within a range that does not impair the purpose of the present application. The method of controlling the light transmittance of the liquid crystal cell is not particularly limited, and for example, it is possible by adjusting the content of the dichroic dye.

As the upper substrate film and the lower substrate film, a known material may be used without any particular limitation. For example, an inorganic film or plastic film such as a glass film, a crystalline or amorphous silicon film, a quartz or indium tin oxide (ITO) film may be used, and a plastic substrate may be used in terms of implementing a flexible device.

Examples of the plastic substrate include triacetyl cellulose (TAC); COP (cyclo olefin copolymer) such as norbornene derivatives; PMMA(poly(methyl methacrylate); PC(polycarbonate); PE(polyethylene); PP(polypropylene); PVA(polyvinyl alcohol); DAC(diacetyl cellulose); Pac(Polyacrylate); PES(poly ether sulfone); PEEK(polyetheretherketon) ); PPS (polyphenylsulfone), PEI (polyetherimide); PEN (polyethylenemaphthatlate); PET (polyethyleneterephtalate); PI (polyimide); PSF (polysulfone); No. 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 may be present on the substrate as needed.

The upper substrate may further include an upper electrode layer 501 between the upper substrate film 101 and the optically transparent adhesive layer 200 . The lower substrate may further include a lower electrode layer 502 between the lower substrate film 102 and the horizontal alignment layer 400 . The upper electrode layer and the lower electrode layer may serve to provide an external action, for example, application of an electric field, so that a material included in the liquid crystal layer transmits or blocks incident light.

In one example, the upper and/or lower electrode layer may include, but is not limited to, a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as ITO (Indium Tin Oxide). The upper and/or lower second electrode layer may be formed by, for example, depositing a metal oxide such as the conductive polymer, conductive metal, conductive nanowire, or indium tin oxide (ITO).

The lower substrate may further include a spacer 600 formed on the lower substrate film 102 . When the lower substrate further includes the lower electrode layer 502 on the lower base film 102 , the spacers 600 may be formed on the lower electrode layer 502 . In this case, the spacer may be in direct contact with the lower electrode layer. The spacer may maintain a gap between the upper substrate and the lower substrate.

In one example, the spacer may exist between the lower electrode layer and the horizontal alignment layer. The spacer may have a partition wall shape. The barrier rib may divide a space between the lower substrate and the upper substrate into two or more spaces. In the present specification, a space partitioned by a partition wall may be referred to as a non-partition wall portion. Since there is no barrier rib in the non-barrier portion, other films or other layers present thereunder may be exposed. For example, the lower electrode layer may be exposed in the non-barrier wall portion. The horizontal alignment layer may cover the barrier rib portion and the lower electrode layer exposed to the non-barrier rib portion between the barrier rib portions. In the liquid crystal cell in which the upper substrate and the lower substrate are bonded, the horizontal alignment layer present on the partition wall of the lower substrate and the optically transparent adhesive of the upper substrate may be in contact with each other.

A liquid crystal compound and additives to be described later, for example, a dichroic dye, a chiral agent, and the like may be present in the region corresponding to the non-barrier wall portion. The shape of the non-barrier wall portion is not particularly limited, and for example, it may be applied without limitation so as to have a polygonal surface such as a circle, an ellipse, or the like. According to an embodiment of the present application, the barrier rib layer may have, for example, a honeycomb shape.

The barrier rib may include a curable resin. The kind in particular of curable resin is not restrict|limited, For example, a thermosetting resin or photocurable resin, for example, an ultraviolet curable resin can be used.

The thermosetting resin may be, for example, a silicone resin, a silicon resin, a fran resin, a polyurethane resin, an epoxy resin, an amino resin, a phenol resin, a urea resin, a polyester resin, or a melamine resin, but is not limited thereto. .

The ultraviolet curable resin is typically an acrylic polymer, for example, a polyester acrylate polymer, a polystyrene acrylate polymer, an epoxy acrylate polymer, a polyurethane acrylate polymer or a polybutadiene acrylate polymer, a silicone acrylate polymer or an alkyl acrylate. A polymer or the like may be used, but is not limited thereto.

According to an embodiment of the present application, the barrier rib pattern may be formed using an acrylic polymer, more specifically, a polyester-based acrylate polymer, but is not limited thereto.

In one example, the barrier rib may be formed by patterning by photolithography. The photolithography process may include a process of applying a curable resin composition on a lower substrate and then irradiating ultraviolet rays through a pattern mask. The pattern mask may be patterned into an ultraviolet transmitting region and an ultraviolet blocking region. The photolithography process may further include a process of washing the curable resin composition irradiated with ultraviolet rays. Since the area irradiated with ultraviolet light is cured, and the area not irradiated with ultraviolet light remains in a liquid phase, it can be removed through a washing process to form a partition wall shape. In the photolithography process, after UV irradiation, a release treatment may be performed on the pattern mask to easily separate the resin composition and the pattern mask, or a release paper may be placed between the layer of the resin composition and the pattern mask.

The width (line width), spacing, thickness, and area ratio of the partition wall portion to the upper substrate or the lower substrate may be appropriately selected within a range that does not impair the purpose of the present application. For example, the width (line width) of the barrier ribs may be in the range of 1 µm to 500 µm, and the spacing of the barrier ribs may be in the range of 10 µm to 5000 µm.

The thickness of the partition wall portion may be appropriately selected in consideration of a desired cell gap. The thickness of the partition wall portion may be, for example, in the range of 1 μm to 30 μm.

The area of the barrier rib portion of the barrier rib layer may be in the range of about 0.1% to 50% with respect to 100% of the total area of the upper substrate or the lower substrate. The area is related to the adhesion between the upper substrate and the lower substrate, and the area of the barrier rib portion of the barrier rib layer may be in the range of about 10% to 20% with respect to 100% of the total area of the upper substrate or the lower substrate. have.

The present application relates to an optical device further comprising the liquid crystal cell and another optical member. The optical device of the present application may include a liquid crystal cell and a polarizer on one surface of the liquid crystal cell. In one example, the polarizer may be attached to one surface of the lower substrate of the liquid crystal cell.

The polarizer may be a passive polarizer. The polarizer may be an absorption polarizer or a reflection polarizer. The polarizer may be a linear polarizer, an elliptically polarizer, or a circular polarizer.

In one example, the polarizer may be an absorption type linear polarizer. At this time, the absorption axis of the polarizer and the alignment direction of the horizontal alignment layer of the liquid crystal cell may be attached to achieve a range of 80 to 100 degrees. According to the first embodiment of the present application, the transmittance measured in a state where an absorption-type linear polarizer is attached to one surface of the lower substrate of the liquid crystal cell and no voltage is applied to the liquid crystal layer may be 1% or less. According to the second embodiment of the present application, the transmittance measured in a state where an absorption-type linear polarizer is attached to one surface of the lower substrate of the liquid crystal cell and no voltage is applied to the liquid crystal layer may be 3% or more. In this case, the liquid crystal layer may further include a dichroic dye.

The optical element may further include known components such as a hard coating layer, an antireflection layer, a layer containing a dye having a near-infrared (NIR) cut function, and a retardation film as other components.

The liquid crystal cell of the present application is advantageous for realization as a flexible device due to an adequate cell gap maintained and excellent adhesion between the upper substrate and the lower substrate, and a desired initial alignment mode can be easily adjusted. Such a liquid crystal cell may be used while being included in a light modulation device. Examples of the light modulation device include, but are not limited to, a smart window, a window protection film, a flexible display device, an active retarder for displaying a 3D image, or a viewing angle control film. A method of configuring the light modulation device as described above is not particularly limited, and a conventional method may be applied as long as the liquid crystal element is used.

The present application can provide a liquid crystal cell in which a cell gap is adequately maintained and a desired initial alignment mode can be easily adjusted, which is advantageous for implementation as a flexible device due to excellent adhesion between the upper substrate and the lower substrate.

1 exemplarily shows an initial horizontally aligned liquid crystal cell.
2 exemplarily shows an initial hybrid alignment liquid crystal cell.
3 shows an example of transmittance measurement according to the viewing angle of the initial horizontally aligned liquid crystal cell.
4 shows an example of transmittance measurement according to the viewing angle of the initial hybrid alignment liquid crystal cell.
5 is a surface energy measurement result of Reference Examples 1 to 6;
6 is a front transmittance graph of Examples 1 to 6;
7 is a graph of transmittance according to viewing angles of Examples 1 to 6;

Hereinafter, the present application will be described in detail through Examples according to the present application and Comparative Examples not according to the present application, but the scope of the present application is not limited by the Examples presented below.

Reference Example 1

OCA-1, a solvent type OCA (KR3700, ShinEtsu, Inc.), was added to the ITO layer of the PC-ITO film in which the ITO (Indium Tin Oxide) layer was deposited on the PC (Polycarbonate) film so that the concentration of the solid content was 25 wt% toluene. The solution mixed with the solvent was applied as a bar coating, dried at 150° C. for 5 minutes, and thermally cured to form an OCA layer.

Reference Example 2

OCA-2 (X-40-3331, ShinEtsu Corporation), a solvent type OCA, was added on the ITO layer of the PC-ITO film in which the ITO (Indium Tin Oxide) layer was deposited on the PC (Polycarbonate) film with a solid content of 25 wt. %, a solution mixed with a toluene solvent was applied as a bar coating, dried at 150° C. for 5 minutes, and thermally cured to form an OCA layer.

Reference Example 3

OCA-3 (SS9064, KCC Corporation), a solvent type OCA, was added to the ITO layer of the PC-ITO film in which the Indium Tin Oxide (ITO) layer was deposited on the PC (Polycarbonate) film so that the solid content was 25 wt% toluene. The solution mixed with the solvent was applied as a bar coating, dried at 150° C. for 5 minutes, and thermally cured to form an OCA layer.

Reference Example 4

OCA-4 (Daio Si-OCA, Daio paper), a solvent type OCA, was added to the ITO layer of the PC-ITO film in which the ITO (Indium Tin Oxide) layer was deposited on the PC (Polycarbonate) film with a solid content of 25 wt. %, a solution mixed with a toluene solvent was applied as a bar coating, dried at 150° C. for 5 minutes, and thermally cured to form an OCA layer.

Reference Example 5

After applying OCA-6 (STP-04-UV, ShinEtst), a solvent-free type OCA, as a bar coating on the ITO layer of the PC-ITO film on which the ITO (Indium Tin Oxide) layer is deposited on the PC (Polycarbonate) film, , 3J/cm ² The OCA layer was formed by photocuring by irradiating ultraviolet rays.

Reference Example 6

After applying OCA-7 (UV-Acryl-4, LGC), a solvent-free type OCA, as a bar coating on the ITO layer of the PC-ITO film on which the ITO (Indium Tin Oxide) layer is deposited on the PC (Polycarbonate) film, , 3J/cm ² The OCA layer was formed by photocuring by irradiating ultraviolet rays.

Measurement example 1. Surface energy measurement

The surface energy was measured using a drop shape analyzer (Drop Shape Analyzer, KRUSS DSA100 product). Drop the deionized water with known surface tension on the surface of the optically clear adhesive layer (OCA layer) and repeat the process of obtaining the contact angle 5 times to obtain the average value of the obtained 5 contact angle values, and the same , drop diiodomethane with known surface tension and repeat the process of obtaining the contact angle 5 times to obtain the average value of the obtained 5 contact angle values. Then, the surface energy was obtained by substituting the numerical value (Strom value) for the surface tension of the solvent by the Owens-Wendt-Rabel-Kaelble method using the obtained average value of the contact angles for deionized water and diiodomethane. The surface energy of the sample (γ ^surface) is considered non-polar molecules in the dispersion forces and the polar inter-molecular interaction forces (γ ^surface = γ ^dispersion + γ ^polar) may be calculated, in the surface energy γ ^surface polar term (γ ^olar ) can be defined as the polarity of the surface.

For the OCA layers formed in Reference Examples 1 to 6, the surface energy was measured by the above method, and the results are shown in FIG. 5 and Table 1.

Surface energy (mN/m) Reference Example 1 (KR3700) 14.92 Reference Example 2 (X-40-3331) 15.4 Reference Example 3 (SS9064) 10.4 Reference Example 4 (Daio Si-OCA) 13.82 Reference Example 5 (STP-04-UV) 21.42 Reference Example 6 (UV-Acryl-4) 33.75

Example 1

The substrate prepared in Reference Example 1 was prepared as an upper substrate.

An acrylic resin composition (trade name: KAD-03, manufacturer: Minutatech) was coated on the ITO layer of a PC-ITO film (Tejin) on which an ITO (Indium Tin Oxide) layer was deposited on a PC (Polycarbonate) film. Then, a spacer was formed by patterning in a honeycomb shape by a photolithography method (height: 18 µm, pitch: 280 µm, line width: 30 µm). Then, a horizontal alignment layer (SE-7492, Nissan Co.) was coated on the spacer to about 300 nm and then rubbed with a rubbing cap to prepare a lower substrate.

A liquid crystal cell was prepared by placing a liquid crystal composition on a lower substrate and squeezing and laminating the upper substrate. The liquid crystal composition is a liquid crystal compound (MAT-16-1235, Merck Corporation) having a positive dielectric anisotropy having a refractive index anisotropy (Δn) of 0.13 and a dichroic dye (X12, BASF Corporation) in a 99:1 weight ratio. composition.

Example 2

A liquid crystal cell was manufactured in the same manner as in Example 1, except that the substrate prepared in Reference Example 2 was used as the upper substrate.

Example 3

A liquid crystal cell was manufactured in the same manner as in Example 1, except that the substrate prepared in Reference Example 3 was used as the upper substrate.

Example 4

A liquid crystal cell was manufactured in the same manner as in Example 1, except that the substrate prepared in Reference Example 4 was used as the upper substrate.

Example 5

A liquid crystal cell was manufactured in the same manner as in Example 1, except that the substrate prepared in Reference Example 5 was used as the upper substrate.

Example 6

A liquid crystal cell was manufactured in the same manner as in Example 1, except that the substrate prepared in Reference Example 6 was used as the upper substrate.

Measurement Example 2. Measurement of frontal transmittance

An optical element in which an absorption-type linear polarizer (single transmittance: about 45%) was attached to one surface of the lower substrate of the liquid crystal cell prepared in Example through OCA (LGC, V310) was manufactured. At this time, the alignment direction (rubbing direction) of the horizontal alignment layer of the lower substrate and the absorption axis of the polarizer were attached to form 90 degrees. Frontal transmittance of the optical element in a state in which no voltage is applied was measured using a haze meter (NDH-5000SP). The transmittance measurement results are shown in FIG. 6 and Table 2.

Transmittance_0V (%) Example 1 (KR3700) 3.48 Example 2 (X-40-3331) 3.5 Example 3 (SS9064) 4.17 Example 4 (Daio Si-OCA) 3.34 Example 5 (STP-04-UV) 0.77 Example 6 (UV-Acryl-4) 0.49

Measurement example 3. Transmittance measurement according to viewing angle

An optical element in which an absorption-type linear polarizer (single transmittance: about 45%) was attached to one surface of the lower substrate of the liquid crystal cell prepared in Example through OCA (LGC, V310) was manufactured. At this time, the alignment direction (rubbing direction) of the horizontal alignment layer of the lower substrate and the absorption axis of the polarizer were attached to form 90 degrees. For the optical element, transmittance according to the viewing angle was measured using LCMS-200 equipment (Seshim Optoelectronics). 3 shows an example of transmittance measurement according to the viewing angle of the initial horizontally aligned liquid crystal cell. 4 shows an example of transmittance measurement according to the viewing angle of the initial hybrid alignment liquid crystal cell. 7 is a graph of transmittance according to a viewing angle. As shown in FIG. 7 , Examples 1 to 4 showed the maximum transmittance at a specific angle due to the tilt of the liquid crystal molecules according to rubbing, and Examples 5 to 6 showed the same transmittance left and right due to horizontal alignment.

Comparative Example 1. ECB mode

Liquid crystal in the same manner as in Example 1, except that a horizontal alignment film (SE-7492, Nissan) was formed to a thickness of 300 nm on the ITO layer of a PC-ITO film (Tejin) as the upper substrate and a rubbing treatment was used. Cells were prepared.

Comparative Example 2. HAN Mode

A liquid crystal cell was prepared in the same manner as in Example 1 except that a vertical alignment film (5661LB3, Nissan Corporation) was formed to a thickness of 300 nm on the ITO layer of the PC-ITO film (Tejin Corporation) as the upper substrate and a rubbing treatment substrate was used. prepared.

Measurement Example 4. Adhesion evaluation

For the liquid crystal cells of Examples 1 to 6 and Comparative Examples 1 to 2, the adhesion strength was evaluated by measuring the 90-degree peel force between the ITO of the upper substrate and the spacer of the lower substrate using a Texture Analyzer, and the results are described in Table 3 did.

90 degree peel force Example 1 (KR3700) 0.18 N/m Example 2 (X-40-3331) 0.15 N/m Example 3 (SS9064) 0.17 N/m Example 4 (Daio Si-OCA) 0.11 N/m Example 5 (STP-04-UV) 0.03 N/m Example 6 (UV-Acryl-4) 0.06 N/m Comparative Example 1 0 N/m Comparative Example 2 0 N/m

101: upper substrate film, 102: lower substrate film, 200: optically transparent adhesive layer, 300: liquid crystal layer, 301: liquid crystal compound, 400: horizontal alignment layer, 501: upper electrode layer, 502: lower electrode layer, 600: spacer

Claims (20)

an upper substrate comprising an upper substrate film and an optically transparent adhesive layer having a surface energy of 19 mN/m or more on one surface of the upper substrate film;
a liquid crystal layer comprising a liquid crystal compound; and
A lower substrate including a lower substrate film and a horizontal alignment film on one surface of the lower substrate film sequentially,
In a state where no voltage is applied to the liquid crystal layer, the liquid crystal compound is present in a horizontally aligned state. an upper substrate comprising an upper substrate film and an optically transparent adhesive layer having a surface energy of 16 mN/m or less on one surface of the upper substrate film;
a liquid crystal layer comprising a liquid crystal compound; and
A lower substrate including a lower substrate film and a horizontal alignment film on one surface of the lower substrate film sequentially,
In a state where no voltage is applied to the liquid crystal layer, the liquid crystal compound is present in a hybrid oriented state. The method of claim 1,
In a state in which no voltage is applied, the tilt angle in the horizontal alignment film surface of the liquid crystal layer and the tilt angle in the optically transparent adhesive layer surface are 10 degrees or less, respectively. The method of claim 1,
In a state in which no voltage is applied, the thickness direction retardation of the liquid crystal layer with respect to a wavelength of 550 nm is less than 50 nm. The method of claim 1,
The surface energy of the optically transparent adhesive layer is 50 mN / m or less liquid crystal cell. The method of claim 1,
The optically transparent adhesive layer is an acrylic adhesive layer of a liquid crystal cell. 3. The method of claim 2,
In a state in which no voltage is applied, the tilt angle on the horizontal alignment layer of the liquid crystal layer is 10 degrees or less, and the tilt angle on the surface of the optically clear adhesive layer is in the range of 80 degrees to 90 degrees. 3. The method of claim 2,
In a state in which no voltage is applied, the thickness direction retardation of the liquid crystal layer with respect to a wavelength of 550 nm is within the range of 50 nm to 400 nm. 3. The method of claim 2,
The surface energy of the optically transparent adhesive layer is 5 mN / m or more liquid crystal cell . 3. The method of claim 2,
The optically transparent adhesive layer is a silicone-based adhesive layer liquid crystal cell. The liquid crystal cell of claim 1 or 2, further comprising a lower electrode layer between the lower base film and the horizontal alignment layer, and further comprising an upper electrode layer between the upper base film and the optically transparent adhesive layer. The liquid crystal cell according to claim 11, further comprising a barrier rib portion formed on the lower electrode layer, wherein the horizontal alignment layer is coated on the barrier rib portion and the lower electrode layer exposed between the barrier rib portion. The liquid crystal cell of claim 12 , wherein the liquid crystal compound is present in a region where a partition wall between the lower substrate and the upper substrate does not exist. The liquid crystal cell according to claim 12, wherein the barrier rib layer comprises a curable resin. According to claim 1, wherein the liquid crystal layer further comprises a dichroic dye, when measuring the transmittance of the liquid crystal cell according to the viewing angle, the liquid crystal exhibiting maximum transmittance within the range of -10 degrees to 10 degrees with respect to the normal direction of the plane of the liquid crystal cell. cell. The liquid crystal cell according to claim 2, wherein the liquid crystal layer further comprises a dichroic dye, and exhibits maximum transmittance within a range of 20 to 60 degrees based on the normal direction of the liquid crystal cell when the transmittance of the liquid crystal cell is measured according to the viewing angle. The liquid crystal cell according to claim 1, wherein the absorption-type linear polarizer is attached to one surface of the lower substrate, and the front transmittance measured in a state where no voltage is applied to the liquid crystal layer is 1% or less. The liquid crystal cell according to claim 2, wherein the absorption-type linear polarizer is attached to one surface of the lower substrate, and the front transmittance measured in a state where no voltage is applied to the liquid crystal layer is 3% or more. An optical element comprising the liquid crystal cell of claim 1 or 2 and a polarizer on one surface of the liquid crystal cell. The optical element according to claim 19, wherein the absorption axis of the polarizer and the alignment direction of the horizontal alignment layer are within a range of 80 degrees to 100 degrees.

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