Liquid crystal composition

Abstract

The present application relates to a liquid crystal composition, which can provide a liquid crystal cell and a variable transmittance device with excellent see-through performance in a dark state, improved clarity, and excellent durability.

Description

[Technical Field]

[0001] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0026100, filed on February 27, 2023, and the entire contents of the documents of this Korean Patent Application are incorporated herein by reference. [Background technology]

[0002] Devices capable of varying transmittance using liquid crystal compounds are known. For example, Patent Document 1 (European Patent Publication No. 0022311) discloses a variable transmittance device using a so-called GH cell (guest host cell), which employs a liquid crystal host material and a dichroic dye guest. In particular, for variable transmittance devices applied to vehicles, devices that allow see-through in a dark state are preferred in terms of visibility. Summary of the Invention [Problem to be solved by the invention]

[0003] The present application relates to a liquid crystal composition that can provide a liquid crystal cell and / or a variable transmittance device that has excellent see-through performance in a dark state, improved clarity, and excellent durability. [Means for solving the problem]

[0004] The present application relates to a liquid crystal composition. The liquid crystal composition can include a liquid crystal material and a dichroic dye. The liquid crystal material can satisfy the following mathematical formula 1:

[0005] [Formula 1] Tni / (△n)^2≧12345.7

[0006] In Equation 1, Tni is the clearing point of the liquid crystal material, and Δn is the refractive index anisotropy of the liquid crystal material.

[0007] When a liquid crystal material satisfying Equation 1 is used, a liquid crystal cell and / or a variable transmittance device can be provided that has excellent visibility in the dark as well as excellent durability. The visibility may refer to the degree to which objects appear clearly when viewed through a liquid crystal cell or variable transmittance device containing the liquid crystal composition. The durability may refer to the ability of the liquid crystal material to maintain a nematic phase and function as a liquid crystal even at high temperatures. This durability may be particularly important when a liquid crystal cell and / or a variable transmittance device containing the liquid crystal composition is used in a high-temperature environment (e.g., summer or a hot climate). This is because if a liquid crystal material does not maintain a nematic phase but instead changes to an isotropic phase in a high-temperature environment, it will no longer function as a liquid crystal. In particular, since vehicles are often exposed to high-temperature environments, the liquid crystal composition may be useful for liquid crystal cells and / or variable transmittance devices for vehicles.

[0008] The formula 1 is defined as the value obtained by dividing Tni of the liquid crystal material by (Δn)^2 of the liquid crystal material, and the Tni / (Δn)^2 value may be specifically 12,500 or more, 13,000 or more, 13,500 or more, 14,000 or more, 14,500 or more, 15,000 or more, 15,500 or more, 16,000 or more, 16,500 or more, 17,000 or more, 17,500 or more, 18,000 or more, 18,500 or more, 19,000 or more, or 19,500 or more. The upper limit of the Tni / (Δn)^2 value in Formula 1 may be, for example, 25,000 or less, 24,000 or less, 23,000 or less, 22,000 or less, 21,000 or less, 20,000 or less, 19,000 or less, 18,000 or less, 17,000 or less, or 16,000 or less.

[0009] In the present specification, when the measurement temperature affects the results of a physical property, the relevant physical property is a physical property measured at room temperature unless otherwise specified. The term "room temperature" refers to a natural temperature without heating or temperature sensing, typically a temperature within the range of about 10°C to 30°C, or about 23°C or about 25°C. Furthermore, unless otherwise specified in the present specification, the unit of temperature is °C. In the present specification, when the measurement pressure affects the results of a physical property, the relevant physical property is a physical property measured at room pressure unless otherwise specified. The term "room pressure" refers to a natural pressure without any increase or decrease in pressure, and typically refers to about 1 atmosphere.

[0010] The liquid crystal material may be a liquid crystal material exhibiting a nematic phase. The nematic phase may refer to a liquid crystal phase in which rod-shaped liquid crystal molecules are aligned parallel to the long axis of the liquid crystal molecules without any regularity in position. The Tni of a liquid crystal material may refer to the temperature at which the liquid crystal material transitions from the nematic phase to the isotropic phase.

[0011] In one example, the clearing point (Tni) of the liquid crystal material may be 85°C or higher. Specifically, the clearing point (Tni) of the liquid crystal material may be 90°C or higher, 95°C or higher, 100°C or higher, 105°C or higher, or 110°C or higher. When the clearing point (Tni) of the liquid crystal material is within the above range, it may be advantageous to exhibit excellent visibility in dark conditions while ensuring durability for vehicles. The upper limit of the clearing point (Tni) of the liquid crystal material may be, for example, 125°C or lower, 120°C or lower, 115°C or lower, 110°C or lower, 105°C or lower, 100°C or lower, 95°C or lower, or 90°C or lower.

[0012] As used herein, the term "refractive index anisotropy" may refer to the difference (ne-no) between the extraordinary refractive index (ne) and the ordinary refractive index (no) of a liquid crystal material. The refractive index anisotropy may be a value measured for light with a wavelength of about 550 nm. In one example, the refractive index anisotropy of the liquid crystal material may be 0.089 or less. Specifically, the refractive index anisotropy of the liquid crystal material may be 0.085 or less, 0.08 or less, 0.075 or less, 0.07 or less, or 0.068 or less. When the refractive index anisotropy of the liquid crystal material is within the above range, the liquid crystal material may exhibit excellent visibility in the dark state, excellent durability, and may be advantageous in reducing the driving voltage. The lower limit of the refractive index anisotropy of the liquid crystal material may be, for example, 0.04 or more, 0.045 or more, 0.05 or more, 0.055 or more, 0.06 or more, 0.065 or more, 0.07 or more, or 0.075 or more.

[0013] The liquid crystal material may include a liquid crystal compound. The liquid crystal material may include the same liquid crystal compound or two or more different liquid crystal compounds. The type of liquid crystal compound may be appropriately selected taking into account the objectives of the present application. In one example, the liquid crystal compound may be a non-reactive liquid crystal compound. A non-reactive liquid crystal compound may refer to a liquid crystal compound that does not have a polymerizable group or a curable group. Examples of the polymerizable group or the curable group include, but are not limited to, 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. Examples of the polymerizable group or the curable group include, but are not limited to, an acryloyl group, an acryloyloxy group, a methacryloyloxy group, a carboxyl group, a hydroxy group, a vinyl group, and an epoxy group. In one example, the liquid crystal composition and / or the liquid crystal material may not include a reactive liquid crystal compound.

[0014] The liquid crystal substance may have a positive or negative dielectric anisotropy. The absolute value of the dielectric anisotropy of the liquid crystal substance may be appropriately selected taking into account the objectives of the present application. The term "dielectric anisotropy (Δε)" may refer to the difference (ε / / -ε⊥) between the horizontal dielectric constant (ε / / ) and the vertical dielectric constant (ε⊥) of the liquid crystal substance. As used herein, the term "horizontal dielectric constant (ε / / )" refers to the dielectric constant measured along the direction of an electric field when a voltage is applied such that the direction of the electric field is substantially horizontal to the director of the liquid crystal substance (liquid crystal compound), and the term "vertical dielectric constant (ε⊥)" refers to the dielectric constant measured along the direction of the electric field when a voltage is applied such that the direction of the electric field is substantially perpendicular to the director of the liquid crystal substance (liquid crystal compound). The dielectric anisotropy of the liquid crystal substance (liquid crystal compound) may be in the range of 5 to 25.

[0015] The dichroic dye can control the light transmittance variable characteristics of the liquid crystal composition and / or liquid crystal layer. As used herein, the term "dye" may refer to a substance that can intensively absorb and / or transform light in at least a portion or all of the visible light range, for example, a wavelength range of 400 nm to 700 nm, and the term "dichroic dye" may refer to a substance that can anisotropically absorb light in at least a portion or all of the visible light range.

[0016] The dichroic dye may be selected from known dyes that are known to have the property of being aligned depending on the alignment state of the liquid crystal material due to the so-called guest-host effect. Examples of such dichroic dyes include azo dyes, anthraquinone dyes, methine dyes, azomethine dyes, merocyanine dyes, naphthoquinone dyes, tetrazine dyes, phenylene dyes, quaterrylene dyes, benzothiadiazole dyes, diketopyrrolopyrrole dyes, squaraine dyes, and pyrromethene dyes, but the dyes applicable in the present application are not limited to these.

[0017] The dichroic dye may have a dichroic ratio, i.e., the ratio of the absorption of light polarized parallel to the long axis of the dichroic dye divided by the absorption of light polarized perpendicular to the long axis, of 5 or more, 6 or more, or 7 or more. The dye may satisfy the dichroic ratio at at least some wavelengths or any one wavelength within the wavelength range of the visible light region, for example, about 380 nm to 700 nm or about 400 nm to 700 nm. The upper limit of the dichroic ratio may be, for example, about 20 or less, 18 or less, 16 or less, or 14 or less.

[0018] The content of the dichroic dye in the liquid crystal composition and / or liquid crystal layer may be appropriately selected taking into account the objectives of the present application. For example, the content of the dichroic dye in the liquid crystal composition and / or liquid crystal layer may be 0.2 wt % or more. Specifically, the content of the dichroic dye may be 0.5 wt % or more, 1 wt % or more, 2 wt % or more, or 3 wt % or more. The upper limit of the content of the dichroic dye may be, for example, 10 wt % or less, 9 wt % or less, 8 wt % or less, 6 wt % or less, or 5 wt % or less. If the content of the dichroic dye is too low, it may be difficult to achieve the desired transmittance variable property, and if the content of the dichroic dye is too high, precipitation may occur. Therefore, it may be advantageous for the content of the dichroic dye to be within the above range.

[0019] The liquid crystal composition may further include a chiral dopant. The chiral dopant may enable the liquid crystal layer to realize a twisted alignment state. Any chiral dopant may be used as long as it can induce the desired twisting without damaging the liquid crystal properties, e.g., nematic regularity. A chiral dopant for inducing rotation in a liquid crystal compound must at least have chirality in its molecular structure. Examples of chiral dopants include compounds having one or more asymmetric carbons, compounds having an asymmetric point on a heteroatom, such as chiral amines or chiral sulfoxides, or compounds having an axially asymmetric, optically active site, such as cumulene or binaphthol. The chiral dopant may be a low-molecular-weight compound having a molecular weight of 1,500 or less. As the chiral agent, commercially available chiral nematic liquid crystals, such as chiral dopant liquid crystal S-811 available from Merck or LC756 available from BASF, can also be used.

[0020] The proportion of the chiral dopant applied is selected so as to achieve a desired d / p ratio in the liquid crystal layer. Generally, the content (wt%) of the chiral dopant can be calculated using the formula: 100 / HTP (Helixcal Twisting Power) × Pitch (p) (nm). The HTP indicates the twist strength of the chiral dopant. The content of the chiral dopant can be determined by taking into account the desired pitch using this formula. In one example, the content of the chiral dopant may be in the range of 0.5 to 10 parts by weight per 100 parts by weight of the liquid crystal material. Specifically, the content of the chiral dopant may be in the range of 1 to 7 parts by weight or 1 to 5 parts by weight per 100 parts by weight of the liquid crystal material.

[0021] The present application also relates to uses of the liquid crystal composition. The present application also relates to a liquid crystal cell including the liquid crystal composition. The liquid crystal cell may include a first substrate, a liquid crystal layer, and a second substrate. The liquid crystal layer may be present between the first substrate and the second substrate. The liquid crystal layer may include the liquid crystal composition.

[0022] 1 shows an example of a liquid crystal cell of the present application. The first substrate may include a first base layer 10a and an adhesive layer 10c. The second substrate may include a second base layer 20a and a spacer 20c. A liquid crystal layer 30 filled with the liquid crystal compound may be present in the space between the first and second substrates.

[0023] The first and second substrate layers may be made of inorganic films such as glass films, crystalline or amorphous silicone films, quartz or ITO (Indium Tin Oxide) films, or polymer films, and a polymer film may be used in view of realizing a flexible device.

[0024] For example, the first and second substrate layers may each be a polymer film. Examples of polymer films include, but are not limited to, triacetyl cellulose (TAC), cycloolefin copolymer (COP) such as norbornene derivatives, poly(methyl methacrylate) (PMMA), polycarbonate (PC), polyethylene (PE), polypropylene (PP), polyvinyl alcohol (PVA), diacetyl cellulose (DAC), polyacrylate (PAC), polyether sulfone (PES), polyetheretherketon (PEEK), polyphenylsulfone (PPS), polyetherimide (PEI), polyethylene maphthate (PEN), polyethyleneterephthlate (PET), polyimide (PI), polysulfone (PSF), polyarylate (PAR), and amorphous fluororesin. The first and second substrate layers may optionally include a coating layer such as gold, silver, or a silicon compound such as silicon dioxide or silicon monoxide, or an anti-reflection layer.

[0025] The first and second substrate layers may each have a thickness within a range of about 10 μm to about 1,000 μm. In other examples, the first and second substrate layers may each have a thickness of about 20 μm or more, 40 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, 120 μm or more, 140 μm or more, 160 μm or more, or about 180 μm or more, or about 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, or about 400 μm or less. When the thicknesses of the first and second substrate layers satisfy the above ranges, defects in appearance such as wrinkles can be reduced when a liquid crystal cell is bonded to an outer substrate to manufacture a variable transmittance device.

[0026] The pressure-sensitive adhesive layer may be present on the inner surface of the first substrate layer. In this specification, the "inner surface" of a component included in a liquid crystal cell may refer to the surface facing the liquid crystal layer.

[0027] The pressure-sensitive adhesive layer may be optically transparent, and may have an average transmittance of about 80% or more, 85% or more, 90% or more, or 95% or more in the visible light region, for example, wavelengths of 380 nm to 780 nm.

[0028] In one example, the pressure-sensitive adhesive layer may be a liquid crystal aligning pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer may be, for example, a vertically aligning pressure-sensitive adhesive layer or a horizontally aligning pressure-sensitive adhesive layer. In this specification, a "vertically aligning pressure-sensitive adhesive" may refer to a pressure-sensitive adhesive having adhesive strength capable of imparting vertical alignment force to adjacent liquid crystal compounds while simultaneously bonding a first substrate and a second substrate. In this specification, a "horizontally aligning pressure-sensitive adhesive" may refer to a pressure-sensitive adhesive having adhesive strength capable of imparting horizontal alignment force to adjacent liquid crystal compounds while simultaneously bonding a first substrate and a second substrate. The free tilt angle of the adjacent liquid crystal compound relative to the vertically aligning pressure-sensitive adhesive may be within a range of 80 to 90 degrees, 85 to 90 degrees, approximately 87 to 90 degrees, or approximately 90 degrees. The free tilt angle of the adjacent liquid crystal compound relative to the horizontally aligning pressure-sensitive adhesive may be within a range of 0 to 10 degrees, 0 to 5 degrees, 0 to 3 degrees, or approximately 0 degree.

[0029] In this specification, the free tilt angle may refer to the angle that the director of the liquid crystal compound forms with respect to a plane horizontal to the liquid crystal alignment adhesive or alignment film when no voltage is applied. In this specification, the director of the liquid crystal compound may refer to the optical axis or slow axis of the liquid crystal layer. Alternatively, if the liquid crystal compound is rod-shaped, the director of the liquid crystal compound may refer to an axis parallel to the long axis of the rod, or if the liquid crystal compound is discotic, the director may refer to an axis parallel to the normal to the disc plane.

[0030] The thickness of the adhesive layer may be, for example, within a range of 3 μm to 15 μm, which may be advantageous in minimizing defects such as pressure-sensitive adhesive squeezing and accumulation when used in the manufacture of a liquid crystal cell while ensuring adhesion between the first and second substrates.

[0031] The adhesive layer may be made of various types of adhesives known in the industry as optically clear adhesives (OCA). The adhesives may be cured before the objects are bonded, which differs from optically clear resin (OCR) adhesives that are cured after the objects are bonded. Examples of the adhesives that may be used include acrylic, silicone, epoxy, and urethane adhesives.

[0032] The adhesive layer may include a cured adhesive resin. In one example, the adhesive layer may be a silicone-based adhesive layer. The silicone-based adhesive layer may include a cured adhesive of a curable silicone compound as the adhesive resin.

[0033] The type of curable silicone compound is not particularly limited, and for example, a heat-curable silicone compound or an ultraviolet-curable silicone compound can be used. The curable silicone compound can be called an adhesive resin.

[0034] In one example, the curable silicone compound may be an addition-cure silicone compound.

[0035] Specific examples of the addition-curable silicone compound include, but are not limited to, (1) organopolysiloxanes containing two or more alkenyl groups in the molecule and (2) organopolysiloxanes containing two or more silicon-bonded hydrogen atoms in the molecule. Such silicone compounds can form cured products by addition reaction in the presence of a catalyst, for example.

[0036] More specific examples of the organopolysiloxane (1) that can be used in the present application include a dimethylsiloxane-methylvinylsiloxane copolymer having both branched chain terminals blocked with trimethylsiloxane groups, a methylvinylpolysiloxane having both branched chain terminals blocked with trimethylcyclohexane groups, a dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer having both branched chain terminals blocked with trimethylsiloxane groups, a dimethylpolysiloxane having both branched chain terminals blocked with dimethylvinylsiloxane groups, a methylvinylpolysiloxane having both branched chain terminals blocked with dimethylvinylsiloxane groups, a dimethylsiloxane-methylvinylsiloxane copolymer having both branched chain terminals blocked with dimethylvinylsiloxane groups, a dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer having both branched chain terminals blocked with dimethylvinylsiloxane groups, and 1 2SiO 1 / 2 The siloxane unit represented by R 1 2nd Round 2 SiO 1 / 2 The siloxane unit represented by SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 2nd Round 2 SiO 1 / 2 The siloxane unit represented by SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 2nd Round 2 SiO 1 / 2 The siloxane unit represented by R 1 SiO 3 / 2 Siloxane units represented by R 2 SiO 3 / 2 Examples of suitable organopolysiloxane copolymers include, but are not limited to, organopolysiloxane copolymers containing siloxane copolymer units represented by the formula: 1is a hydrocarbon group other than an alkenyl group, and specifically may be 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; an aryl group 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; or a halogen-substituted alkyl group such as a chloromethyl group, a 3-chloropropyl group, or a 3,3,3-trifluoropropyl group. 2 is an alkenyl group, and specifically may be a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, or the like.

[0037] More specific examples of the (2) organosiloxane that can be used in the present application include methylhydrogenpolysiloxanes capped at both molecular chain terminals with trimethylsiloxane groups, dimethylsiloxane-methylhydrogen copolymers capped at both molecular chain terminals with trimethylsiloxane groups, dimethylsiloxane-methylhydrogensiloxane-methylphenylsiloxane copolymers capped at both molecular chain terminals with trimethylsiloxane groups, dimethylpolysiloxanes capped at both molecular chain terminals with dimethylhydrogensiloxane groups, dimethylsiloxane-methylphenylsiloxane copolymers capped at both molecular chain terminals with dimethylhydrogensiloxane groups, methylphenylpolysiloxanes capped at both molecular chain terminals with dimethylhydrogensiloxane groups, R 1 3SiO 1 / 2 The siloxane unit represented by R 1 2HSiO 1 / 2 The siloxane unit represented by SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 2HSiO 1 / 2 The siloxane unit represented by SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 HSiO 2 / 2 The siloxane unit represented by R 1 SiO 3 / 2 Siloxane units or HSiO 3 / 2Examples of suitable organopolysiloxanes include, but are not limited to, organopolysiloxane copolymers containing siloxane units represented by the formula: 1 is a hydrocarbon group other than an alkenyl group, and specifically may be 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; an allyl group 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; or a halogen-substituted alkyl group such as a chloromethyl group, a 3-chloropropyl group, or a 3,3,3-trifluoropropyl group.

[0038] When the pressure-sensitive adhesive layer is a vertically aligning pressure-sensitive adhesive layer, the surface energy of the pressure-sensitive adhesive layer may be 16 mN / m or less. The lower limit of the surface energy may be, for example, 5 mN / m or more. When the pressure-sensitive adhesive layer is a horizontally aligning pressure-sensitive adhesive layer, the surface energy of the pressure-sensitive adhesive layer may be more than 16 mN / m. The upper limit of the surface energy may be, for example, 50 mN / m or less. The surface energy may be measured using a drop shape analyzer (DSA100 product from KRUSS). Specifically, deionized water with a known surface tension is dropped onto the pressure-sensitive adhesive surface, and the contact angle is measured five times. The average of the five contact angles is calculated. Similarly, diiodomethane with a known surface tension is dropped onto the pressure-sensitive adhesive surface, and the average of the five contact angles is calculated five times. The surface energy can then be calculated by substituting the Strom value for the surface tension of the solvent using the Owens-Wendt-Rabel-Kaelble method using the average contact angles for deionized water and diiodomethane. The surface energy (γsurface) of a sample can be calculated by considering the dispersion force between nonpolar molecules and the interaction force between polar molecules (γsurface = γdispersion + γpolar), and the proportion of the polar term (γpolar) in the surface energy (γsurface) can be defined as the polarity of the surface.

[0039] The first and second substrates of the liquid crystal cell may be attached by the adhesive force of an adhesive layer. In one example, the adhesive layer of the first substrate and the spacer of the second substrate may be attached. In one example, if an alignment film is formed on the spacer of the second substrate, a region of the alignment film corresponding to the spacer may be attached to the adhesive layer of the first substrate.

[0040] The pressure-sensitive adhesive layer may have a storage modulus of 1 MPa or less. The lower limit of the storage modulus of the pressure-sensitive adhesive layer may be, for example, 0.01 MPa or more. Specifically, the storage modulus of the pressure-sensitive adhesive layer may be 0.02 MPa or more, 0.04 MPa, 0.06 MPa, 0.08 MPa, or 0.1 MPa or more, or 0.8 MPa or less, 0.6 MPa or less, 0.4 MPa or less, or 0.2 MPa or less. The storage modulus may be a value measured at a temperature of 25°C and a frequency of 6 rad / sec.

[0041] The spacers 20c can maintain the distance between the first and second substrates, and a liquid crystal layer can be present in the area where there are no spacers between the first and second substrates.

[0042] The spacers may be patterned. The spacers may have a partition wall shape. When the spacers have a partition wall shape, it may be more advantageous in terms of improving the clarity of a see-through image. The partition walls may divide the space between the first and second substrates into two or more spaces. In areas where there are no spacers, other films or layers present underneath may be exposed. For example, in areas where there are no spacers, the second electrode layer may be exposed. An alignment film may cover the spacers and the second electrode layer exposed in areas where there are no spacers. In a liquid crystal cell in which the first and second substrates are bonded together, the alignment film present on top of the spacers of the second substrate and the adhesive layer of the upper substrate may be in contact with each other.

[0043] The spacer-free region between the first and second substrates may contain the liquid crystal material and the above-mentioned additives, such as dichroic dyes, chiral agents, etc. The cross-sectional shape of the space between the partition walls of the spacer is not particularly limited and may be, for example, a circle, an ellipse, or any other polygonal shape having multiple faces.

[0044] The spacer may include a curable resin. The type of curable resin is not particularly limited, and may be, for example, a thermosetting resin or a photocurable resin, such as an ultraviolet-curable resin. Examples of thermosetting resins that may be used include, but are not limited to, silicone resin, silicon resin, furan resin, polyurethane resin, epoxy resin, amino resin, phenol resin, urea resin, polyester resin, and melamine resin. Examples of ultraviolet-curable resins that may be used include, but are not limited to, acrylic polymers, such as polyester acrylate polymers, polystyrene acrylate polymers, epoxy acrylate polymers, polyurethane acrylate polymers, polybutadiene acrylate polymers, silicone acrylate polymers, and alkyl acrylate polymers.

[0045] The spacers may be formed by a patterning process. For example, the spacers may be formed by a photolithography process. The photolithography process may include a process of applying a curable resin composition to a substrate layer or an electrode layer and then irradiating the curable resin composition with ultraviolet light using a pattern mask. The pattern mask may be patterned into ultraviolet-transmitting and ultraviolet-blocking regions. The photolithography process may further include a process of washing the curable resin composition irradiated with ultraviolet light. The regions irradiated with ultraviolet light are cured, while the regions not irradiated with ultraviolet light remain liquid, which can be removed through a washing process to form a pattern in the shape of a partition wall. In the photolithography process, the pattern mask may be subjected to a release treatment or a release paper may be placed between the resin composition layer and the pattern mask to easily separate the resin composition from the pattern mask after ultraviolet light irradiation.

[0046] The width (line width), spacing (pitch), thickness, and area of ​​the spacers may be appropriately selected within ranges that do not impair the objectives of the present application. For example, the width (line width) of the spacers may be in the range of 10 μm to 500 μm or 10 μm to 50 μm. The spacing (pitch) of the spacers may be in the range of 10 μm to 1000 μm or 100 μm to 1000 μm. The area of ​​the spacers may be approximately 5% or more, or 50% or less, of the total area (100%) of the second base layer. When the area of ​​the spacers is within the above ranges, it may be advantageous to ensure excellent electro-optical properties while adequately ensuring adhesion between the upper and lower substrates. The thickness of the spacers may be, for example, in the range of 1 μm to 30 μm or 3 μm to 20 μm.

[0047] The first substrate may further include a first electrode layer 10b between the first base layer 10a and the adhesive layer 10c. The second substrate may further include a second electrode layer 20b between the second base layer 20a and the spacer 20c. The first and second electrode layers may apply an external action, such as an electric field, to allow materials contained in the liquid crystal layer to transmit or block incident light. In one example, the first and / or second electrode layers may include, but are not limited to, a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as ITO (Indium Tin Oxide). The first and second electrode layers may each be formed by depositing, for example, the conductive polymer, the conductive metal, the conductive nanowire, or a metal oxide such as ITO (Indium Tin Oxide).

[0048] The second substrate may further include an alignment film 20d. The spacer 20c may be present between the second base layer 20a and the alignment film 20d. If the second substrate includes the second electrode layer 20b, the spacer 20c may be present between the second electrode layer 20b and the alignment film 20d. The alignment film may be formed on the spacer. That is, the top and / or side surfaces of the spacer may be in contact with the alignment film. The bottom surface of the spacer may be in contact with the second electrode layer. The adhesive layer included in the first substrate may have liquid crystal alignment properties and may therefore not include an alignment film. That is, an alignment film may not be formed on the inner surface of the first electrode layer.

[0049] The alignment film and the liquid crystal layer may be in contact with each other. The alignment film may be a vertical alignment film or a horizontal alignment film. Herein, the term "horizontal alignment film" may refer to a layer containing an alignment substance that imparts horizontal alignment force to liquid crystal compounds present in an adjacent liquid crystal layer. Herein, the term "vertical alignment film" may refer to a layer containing an alignment substance that imparts vertical alignment force to liquid crystal compounds present in an adjacent liquid crystal layer. The free tilt angle of the adjacent liquid crystal compounds relative to the vertical alignment film may be within a range of 80° to 90°, 85° to 90°, approximately 87° to 90°, or approximately 90°, and the free tilt angle of the adjacent liquid crystal compounds relative to the horizontal alignment film may be within a range of 0° to 10°, 0° to 5°, 0° to 3°, or approximately 0°. Unlike an adhesive layer, the alignment film may not have adhesive strength to bond the upper and lower substrates. In one example, the peel strength of the alignment film relative to the first substrate may be close to zero in the state of the liquid crystal cell of FIG. 1.

[0050] The alignment film may be a rubbed alignment film or a photo-aligned film. The alignment direction of the alignment film may be the rubbing direction in the case of a rubbed alignment film, or the direction of polarized light in the case of a photo-aligned film. The alignment direction can be confirmed by a detection method using an absorptive linear polarizer. Specifically, the alignment direction can be confirmed by placing an absorptive linear polarizer on one side of the liquid crystal layer while aligning the liquid crystal compound contained in the liquid crystal layer horizontally and measuring the transmittance while rotating the polarizer 360 degrees. In this state, when light is irradiated onto the liquid crystal layer or the absorptive linear polarizer side and the brightness (transmittance) is measured on the other side, the transmittance tends to be low when the absorption axis or transmission axis coincides with the alignment direction of the liquid crystal alignment film. However, the alignment direction can be confirmed by simulation that reflects the refractive index anisotropy of the applied liquid crystal compound. Methods for determining the alignment direction depending on the mode of the liquid crystal layer are well known, and in this application, the alignment direction of the alignment film can be confirmed using such a known method.

[0051] Examples of the alignment film include known substances that exhibit alignment ability through rubbing alignment, such as polyimide compounds, poly(vinyl alcohol) compounds, poly(amic acid) compounds, polystyrene (polystylene) compounds, polyamide compounds, and / or polyoxyethylene compounds, as well as polyimide compounds, polyamic acid compounds, polynorbornene compounds, phenylmaleimide copolymer compounds, polyvinylcinnamate compounds, polyazobenzene compounds, polyethyleneimide compounds, polyvinylalcohol compounds, polyimide compounds, polyethylene (polyethylene) compounds, polystyrene (polystylene) compounds, polyphenylenephthalamide compounds, polyester compounds, CMPI (chloromethylated The material may include, but is not limited to, one or more selected from the group consisting of known materials that can exhibit alignment ability upon light irradiation, such as a polyimide compound, a PVCI (polyvinyl cinnamate) compound, and / or a polymethyl methacrylate compound.

[0052] In this specification, a combination of a first substrate layer, a first electrode layer, and an adhesive layer may be referred to as a first substrate, and a combination of a second substrate layer, a second electrode layer, a spacer, and an alignment layer may be referred to as a second substrate. In a liquid crystal cell, the first substrate does not include a separate alignment layer other than the adhesive layer, and the lower substrate may include an alignment layer.

[0053] The liquid crystal material in the liquid crystal layer can switch its alignment state by application of an external action. As used herein, the term "external action" refers to any external factor, such as an external voltage, that can affect the behavior of the material contained in the liquid crystal layer. Therefore, a state without an external action refers to a state in which no external voltage or the like is applied.

[0054] A liquid crystal layer containing a liquid crystal material and a dichroic dye may be a GHLC (guest-host liquid crystal) layer. Herein, the term "GHLC (guest-host liquid crystal) layer" refers to a functional layer in which the dichroic dye is aligned with the alignment of the liquid crystal material, and exhibits anisotropic light absorption characteristics in both the alignment direction of the dichroic dye and the direction perpendicular to the alignment direction. For example, a dichroic dye is a material whose light absorption rate varies depending on the polarization direction. If the dichroic dye has a high absorption rate for light polarized along its long axis, it is called a p-type dye, and if the dichroic dye has a high absorption rate for light polarized along its shortening axis, it is called an n-type dye. For example, when a p-type dye is used, polarized light vibrating along the long axis of the dye is absorbed, and polarized light vibrating along the shortening axis of the dye is transmitted due to low absorption. Hereinafter, unless otherwise specified, the dichroic dye is assumed to be a p-type dye.

[0055] The thickness of the liquid crystal layer is not particularly limited, and may be, for example, about 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.5 μm or more, 1 μm or more, 1.5 μm or more, 2 μm or more, 2.5 μm or more, 3 μm or more, 3.5 μm or more, 4 μm or more, 4.5 μm or more, 5 μm or more, 5.5 μm or more, 6 μm or more, 6.5 μm or more, 7 μm or more, 7.5 μm or more, or 8 μm or more. The upper limit of the thickness of the liquid crystal layer is not particularly limited, and may generally be about 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0056] The alignment state of the liquid crystal layer can be switched depending on the voltage applied to the liquid crystal cell. For example, when no voltage is applied to the liquid crystal cell, the liquid crystal layer may have a first alignment state, and when a voltage is applied to the liquid crystal cell, the liquid crystal layer may have a second alignment state different from the first alignment state. Examples of the first alignment state and the second alignment state include a horizontal alignment state, a vertical alignment state, a twist alignment state, a tilt alignment state, and a hybrid alignment state, respectively.

[0057] In this specification, the term "horizontal alignment state" refers to a state in which the directors of the liquid crystal material in the liquid crystal layer are aligned approximately 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 may be, for example, within a range of approximately -10 degrees to 10 degrees, or -5 degrees to 5 degrees, or may be approximately 0 degrees.

[0058] As used herein, the term "vertical alignment state" refers to a state in which the directors of the liquid crystal material in the liquid crystal layer are aligned approximately perpendicular 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 may be, for example, within a range of approximately 80 to 100 degrees, or 85 to 95 degrees, or may be approximately 90 degrees.

[0059] In this specification, the term "twisted alignment state" refers to a helical structure in which directors of a liquid crystal material in a liquid crystal layer are twisted along a virtual helical axis to form a layer. The twisted alignment state can be realized as a vertical, horizontal, or tilted alignment state. That is, the vertical twist alignment mode is a state in which individual liquid crystal compounds are twisted along a helical axis in a vertically aligned state to form a layer, the horizontal twist alignment mode is a state in which individual liquid crystal compounds are twisted along a helical axis in a horizontally aligned state to form a layer, and the tilted twist alignment mode is a state in which individual liquid crystal compounds are twisted along a helical axis in a tilted aligned state to form a layer.

[0060] In this specification, the term "hybrid alignment state" may refer to an alignment state in which the tilt angle, which is the angle between the director of the liquid crystal material in the liquid crystal layer and the plane of the liquid crystal layer, gradually increases or decreases along the thickness direction of the liquid crystal layer.

[0061] In one example, the first alignment state may be a twisted alignment state, i.e., the liquid crystal layer can be switched between a twisted alignment and an alignment state different from the twisted alignment by applying an external force.

[0062] In one example, the liquid crystal layer can be switched between a twisted alignment state and a homeotropic alignment state, and in one example, the liquid crystal layer may be in the twisted alignment state when no voltage is applied and in the homeotropic alignment state when a voltage is applied.

[0063] In the twisted alignment state, the ratio (d / p) of the liquid crystal layer thickness (d) to the pitch (p) may be 1 or greater. The upper limit of the ratio (d / p) may be, for example, 8 or less. Specifically, the ratio (d / p) may be 2 or greater or 3 or greater, and may be 7 or less, 6 or less, 5 or less, or 4 or less. When the ratio (d / p) of the liquid crystal layer thickness (d) to the pitch (p) is within the above range, the transmissive device may exhibit excellent light transmittance tunability and excellent visibility even in the dark state, and may be advantageous in terms of excellent durability and low driving voltage. Typically, when the ratio (d / p) is 0.5 or greater and 1.0 or less, it may be referred to as an STN (Super Twisted Nematic) mode, and when the ratio (d / p) exceeds 1.0, it may be referred to as an HTN (Highly Twisted Nematic) driving mode.

[0064] The pitch (p) of the liquid crystal layer can be measured using a wedge cell, specifically, by the method described in "Simple method for accurate measurements of the cholesteric pitch using a stripe-wedge Grandjean-Cano cell" by D. Podolskyy et al. (Liquid Crystals, Vol. 35, No. 7, July 2008, pp. 789-791). The ratio (d / p) can be achieved by introducing an appropriate amount of chiral dopant into the liquid crystal layer.

[0065] The driving mode of the liquid crystal cell can be appropriately selected as needed. Examples of driving modes for the liquid crystal cell include electrically controlled birefringence (ECB) mode, twisted nematic (TN) mode, super twisted nematic (STN) mode, reverse twisted nematic (RTN) mode, reverse super twisted nematic (RSTN) mode, hybrid aligned nematic (HAN) mode, twisted hybrid aligned nematic (Twisted HAN) mode, super twisted hybrid aligned nematic (Super twisted HAN) mode, in-plane switching (IPS) mode, and vertical alignment (VA) mode. Depending on the desired driving mode of the liquid crystal cell, the type of liquid crystal, the type of alignment film, the type of additive, and the like can be appropriately selected.

[0066] The liquid crystal cell may exhibit excellent clarity even in a dark state. The liquid crystal cell may realize a dark state when no voltage is applied. In one example, the liquid crystal cell may satisfy the following Equation 2:

[0067] [Formula 2] A / B×100%≧80%

[0068] In Equation 2, A is the MTF (Modulation Transfer Function) 50 value measured for the liquid crystal cell when no voltage is applied, and B is the MTF (Modulation Transfer Function) 50 value measured in air.

[0069] The A / B ratio in Equation 2 may be an index indicating the clarity of the liquid crystal cell relative to air. The A / B x 100% value may be, for example, 82% or more, 84% or more, 86% or more, 88% or more, 90% or more, 92% or more, 94% or more, or 96% or more. A higher A / B ratio (%) in Equation 2 indicates better clarity, so the upper limit is not particularly limited and may be, for example, 99% or less or 97% or less. The MTF50 value (A) of the liquid crystal cell may be 45 Cy / mm or more, 46 Cy / mm or more, 47 Cy / mm or more, 48 Cy / mm or more, 49 Cy / mm or more, 50 Cy / mm or more, 51 Cy / mm or more, or 52 Cy / mm or more, or may be less than 54.87 Cy / mm, 54 Cy / mm or less, or 53 Cy / mm or less. The MTF50 value in air may be 54.87 Cy / mm.

[0070] The present application relates to uses of the liquid crystal composition and / or liquid crystal cell. The liquid crystal composition and / or liquid crystal cell can be used, for example, in a variable transmittance device. That is, the present application relates to a variable transmittance device including the liquid crystal cell. The variable transmittance device can change its transmittance by switching the alignment states of the liquid crystal material and the dichroic dye.

[0071] In this specification, the term "variable transmittance device" may refer to a device capable of switching between at least two or more different light states. The different light states may refer to states having at least different transmittances. Examples of states that the variable transmittance device can implement include a transmissive mode state and a blocking mode state. In one example, the variable transmittance device of the present application may be a device capable of switching between at least the transmissive mode state and the blocking mode state. The transmissive state may be a bright state, and the blocking state may be a dark state.

[0072] The transmittance of the variable transmittance device in the transmission mode may be at least 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%. The transmittance of the variable transmittance device in the blocking mode may be 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, or 5%. Since a higher transmittance is advantageous in the transmission mode and a lower transmittance is advantageous in the blocking mode, the upper and lower limits of the transmittance in the transmission mode and the blocking mode are not particularly limited. For example, the upper limit of the transmittance in the transmission mode may be less than about 100%, and the lower limit of the transmittance in the blocking mode may be greater than about 0%.

[0073] In one example, in the variable transmittance device that can switch between the transmission mode state and the blocking mode state, the difference between the transmittance in the transmission mode state and the blocking mode state (transmission mode transmittance - transmission mode transmittance) may be 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, or 40% or more, or may be 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, 50% or less, or 45% or less.

[0074] The transmittance may be, for example, a rectilinear transmittance. The rectilinear transmittance is a percentage of light transmitted in the same direction as the incident direction relative to the light incident on the device. For example, if the device is in the form of a film or sheet, the transmittance can be defined as the percentage of light incident in a direction aligned with the normal direction of the film or sheet surface that is transmitted through the device in a direction aligned with the normal direction.

[0075] The transmittance may be the transmittance for one wavelength in the visible light range, for example, within a range of about 400 to 700 nm or about 380 to 780 nm, the transmittance for the entire visible light range, the maximum or minimum transmittance among the transmittances for the entire visible light range, or the average transmittance within the visible light range. In another example, the transmittance may be the transmittance for light with a wavelength of about 550 nm.

[0076] The variable transmittance device may further include an outer substrate. In one example, the variable transmittance device may include a first outer substrate, the liquid crystal cell, and a second outer substrate, in that order. The outer substrate may be advantageous in overcoming physical limitations of the liquid crystal cell.

[0077] The first outer substrate and the second outer substrate may each independently be an inorganic substrate or a plastic substrate. The inorganic substrate is not particularly limited and may be a known inorganic substrate. For example, a glass substrate having excellent light transmittance may be used as the inorganic substrate. Examples of the glass substrate include, but are not limited to, a soda lime glass substrate, a general tempered glass substrate, a borosilicate glass substrate, or an alkali-free glass substrate. Examples of the polymer substrate include cellulose films such as TAC (triacetyl cellulose) or DAC (diacetyl cellulose); COP (cycloolefin copolymer) films such as norbornene derivatives; acrylic films such as PAR (Polyacrylate) or PMMA (poly(methyl methacrylate)); PC (polycarbonate) films; polyolefin films such as PE (polyethylene) or PP (polypropylene); PVA (polyvinyl Examples of suitable materials include, but are not limited to, a polyimide (PI) film; a sulfone-based film such as a polysulfone (PSF) film, a polyphenylsulfone (PPS) film, or a polyethersulfone (PES) film; a polyetheretherketone (PEEK) film; a polyetherimide (PEI) film; a polyester-based film such as a polyethylene naphthate (PEN) film or a polyethyleneterephtalate (PET) film; or a fluororesin film. The first and second outer substrates may each have a functional layer, such as a gold coating layer, a silver coating layer, or a silicate compound coating layer such as silica dioxide or silica monoxide, or an anti-reflection layer, as needed. In one example, at least one of the first and second outer substrates may be a glass substrate, or the other outer substrate may be a plastic substrate. In another example, the first and second outer substrates may each be a glass substrate.

[0078] The area of ​​the first outer substrate and / or the second outer substrate may be larger than the area of ​​the first base layer and / or the second base layer. The first outer substrate and the second outer substrate may be flat or curved. For example, the first outer substrate and the second outer substrate may both be flat or curved, or one may be flat and the other curved. If both are curved, the curvatures or radii of curvature may be the same or different. The curvatures or radii of curvature herein may be measured using methods known in the art, such as non-contact equipment such as a 2D profile laser sensor, a chromatic confocal line sensor, or a 3D measuring confocal microscope. Methods for measuring the curvatures or radii of curvature using such equipment are well known.

[0079] The thickness of each of the first outer substrate and the second outer substrate may be about 0.3 mm or more. In other examples, the thickness may be about 0.5 mm or more, 1 mm or more, 1.5 mm or more, or about 2 mm or more, or about 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, or about 3 mm or less.

[0080] The first and second outer substrates may be bonded to the liquid crystal cell by adhesive layers, which may be thermoplastic polyurethane (TPU), polyamide, polyester, ethylene vinyl acetate (EVA), acrylic, silicone, or polyolefin adhesive layers.

[0081] An autoclave process may be performed to bond the first outer substrate and the second outer substrate to the liquid crystal cell. The autoclave process may be performed by heating and / or pressurizing a laminate in which the first outer substrate and the second outer substrate are laminated to the liquid crystal cell with an adhesive layer. If the variable transmittance device further includes another optical member, the laminate may further include the optical member. The conditions for the autoclave process are not particularly limited and may be performed under appropriate temperature and pressure depending on the type of adhesive layer applied. Typical autoclave processes are performed at temperatures of about 80°C or higher, 90°C or higher, or 100°C or higher, and at pressures of 2 atmospheres or higher, but are not limited thereto. The upper limit of the process temperature may be about 200°C or lower, 190°C or lower, 180°C or lower, or 170°C or lower, and the upper limit of the process pressure may be about 10 atmospheres or lower, 9 atmospheres or lower, 8 atmospheres or lower, 7 atmospheres or lower, or 6 atmospheres or lower.

[0082] The liquid crystal cell and / or the variable transmittance device may be applied to a device requiring variable transmittance characteristics. In one example, the variable transmittance device may be a sunroof for a vehicle. For example, the present application relates to a vehicle including a vehicle body having one or more openings formed therein and the liquid crystal cell or the variable transmittance device installed in the opening. Alternatively, the liquid crystal cell and / or the variable transmittance device may be applied to the lens portion of sunglasses or eyewear, or may be applied to smart windows for buildings, etc. Examples of the eyewear include eyewear for AR (Augmented Reality) or VR (Virtual Reality). [Effects of the Invention]

[0083] The liquid crystal composition of the present application can provide a liquid crystal cell and a transmittance variable device that have excellent see-through performance in a dark state, improves clarity, and is also excellent in durability. [Brief explanation of the drawings]

[0084] [Figure 1] 1 is a diagram illustrating an example of a liquid crystal cell of the present application.

[0085] [Figure 2] This is an image that observes clarity.

[0086] [Figure 3] This is an image of whether or not a rainbow band occurs. DETAILED DESCRIPTION OF THE INVENTION

[0087] Hereinafter, the present application will be described in detail through examples according to the present application, but the scope of the present application is not limited to the examples presented below.

[0088] Measurement example 1. Measurement of MTF (Modulation Transfer Function) 50

[0089] The MTF50 value was measured as an indicator of sharpness for a liquid crystal cell in a dark state (without applied voltage). MTF expresses the sensitivity to luminance of a striped object, where the luminance varies sinusoidally, as a function of spatial frequency. As an indicator of image sharpness, MTF50 is the spatial frequency at which luminance drops to 50% of its low-frequency value. A higher MTF50 value indicates superior sharpness of the liquid crystal cell. The MTF50 value was measured using an SRF plus chart and Imatest software according to the Imatest manual. Specifically, the MTF50 value can be obtained by placing an SRF plus chart under LED illumination and quantifying the sharpness of the image on the chart as it passes through the liquid crystal cell. The sharpness of the liquid crystal cell in air was measured as A / B x 100%, where A is the MTF50 value of the liquid crystal cell and B is the MTF50 value in air. The MTF50 value in air, which is the MTF50 value in air without any object including a liquid crystal cell, was 54.87 Cy / mm.

[0090] Measurement example 2: Measurement of total transmittance (TT)

[0091] The total transmittance of the liquid crystal cell in a dark state (without voltage applied) was measured using a haze meter (NDH5000SP, SECOS) according to ASTM D1003 standard.

[0092] Specifically, when light with a wavelength of 380 nm to 780 nm is incident on a measurement object within an integrating sphere, the incident light is separated into diffused light (DT, the sum of all diffused light) and direct light (PT, light emitted in the front direction excluding diffused light) by the measurement object. The diffused light and direct light can be collected on a light-receiving element within the integrating sphere and measured separately. Through this process, the total transmitted light (TT) can be determined as the sum (DT + PT) of the diffused light (DT) and direct light (PT). The total transmitted light refers to the total transmittance. The total transmittance is the average value for light with a wavelength of 380 nm to 780 nm.

[0093] Evaluation example 1. Visibility evaluation of objects

[0094] A liquid crystal cell was placed between the object (acetone bottle) and the camera, and the image was captured with the camera and evaluated for clarity with the naked eye. The distance between the object and the liquid crystal cell was 15 cm. Figure 2 shows the captured images (a: Example 1, b: Example 2, c: Example 3, d: Comparative Example 1, e: Comparative Example 2).

[0095] Evaluation example 2: Evaluation of rainbow band occurrence

[0096] A liquid crystal cell was placed under a fluorescent lamp, and a camera was placed under the liquid crystal cell. The light from the fluorescent lamp was then photographed through the camera to observe whether or not a rainbow band was generated. Figure 3 shows the photographed images (a: Example 1, b: Example 2, c: Example 3, d: Comparative Example 1, e: Comparative Example 2).

[0097] Example 1

[0098] A liquid crystal composition was prepared by mixing 100 parts by weight of a liquid crystal material (ZKC-5115xx, JNC Co.) having a refractive index anisotropy (Δn) of 0.076, a clearing point (Tni) of 91.5°C, and a Tni / (Δn)^2 value of approximately 15841.4 with 3 parts by weight of a dichroic dye (NKX-4010, Hayashibara) and 3.5 parts by weight of a chiral dopant (S811, Merck).

[0099] An adhesive composition was prepared by mixing an OCA-type adhesive resin (KR3700, Shin-Etsu Co.) with a toluene solvent to a solids concentration of 25 wt%. The adhesive composition was bar-coated onto a fluorine-containing release film (FSC6, Nippa Co.) and then heated at 140°C for 5 minutes to form an adhesive layer with a final thickness of approximately 10 μm. The adhesive layer was laminated onto the ITO layer of a PET-ITO film to prepare a first substrate. The PET-ITO film was a film in which an ITO (indium tin oxide) layer with a thickness of approximately 30 nm was vapor-deposited on a highly oriented PET (polyethyleneterephtalate) film (OCF, SKC Co.), with a total thickness of approximately 145 μm. The first substrate thus prepared had a laminated structure consisting of a highly oriented PET film / ITO layer / adhesive layer / release film in this order.

[0100] An acrylic resin composition (product name: KAD-03, manufacturer: MINUTA Tech) was coated on the ITO layer of the same PET-ITO film used for the first substrate, and then photolithographically patterned into a rectangular shape to form partition-shaped spacers. The partition height was 8 μm, the pitch (the distance between two opposing rectangular surfaces) was 350 μm, and the line width was 15 μm. A horizontal alignment film (SE-7492, Nissan) was then coated on the spacers to a thickness of approximately 300 nm, and the surface was rubbed with a rubbing cloth to produce the second substrate.

[0101] The liquid crystal composition was coated on the alignment layer of the second substrate. After peeling off the fluorine release film from the first substrate, the first substrate was bonded to the second substrate to prepare a liquid crystal cell. The liquid crystal cell was a highly twisted nematic liquid crystal cell with a cell gap (d) of 8 μm and a d / p ratio of 3.

[0102] The MTF50 value of the liquid crystal cell of Example 1 was 52.84 Cy / mm, the clarity (compared to air) was 96.29%, and the total transmittance (%) was 11.0%. In addition, as shown in Figure 2, Example 1 provided a very clear see-through image, and as shown in Figure 3, it was confirmed that no rainbow bands were generated even under fluorescent lighting.

[0103] Example 2

[0104] A liquid crystal cell was fabricated in the same manner as in Example 1, except that the liquid crystal material was changed to a liquid crystal material (HAE625484, HCCH) with a refractive index anisotropy (Δn) of 0.067, a clearing point (Tni) of 86°C, and a Tni / (Δn)^2 value of approximately 19603.5. The MTF50 value of the liquid crystal cell of Example 2 was 51.36 Cy / mm, the clarity (relative to air) was 93.59%, and the total transmittance (%) was 11.3%. Furthermore, as shown in Figure 2, Example 2 produced a very clear, see-through image, and as shown in Figure 3, it was confirmed that no rainbow banding occurred even under fluorescent lighting.

[0105] Example 3

[0106] A liquid crystal cell was fabricated in the same manner as in Example 1, except that the liquid crystal material was changed to a liquid crystal material (CSM9056, HCCH) with a refractive index anisotropy (Δn) of 0.078, a clearing point (Tni) of 110°C, and a Tni / (Δn)^2 value of approximately 18080.2. The MTF50 value of the liquid crystal cell of Example 3 was 52.81 Cy / mm, the clarity (relative to air) was 96.24%, and the total transmittance (%) was 11.5%. Furthermore, as shown in Figure 2, Example 3 produced a very clear, see-through image, and as shown in Figure 3, it was confirmed that no rainbow banding occurred even under fluorescent lighting.

[0107] Comparative Example 1

[0108] A liquid crystal cell was fabricated in the same manner as in Example 1, except that the liquid crystal material was changed to a liquid crystal material (MDA-12-1121, Merck) with a refractive index anisotropy (Δn) of 0.1349, a clearing point (Tni) of 114.5°C, and a Tni / (Δn)^2 value of approximately 6291.9. The MTF50 value of the liquid crystal cell of Comparative Example 1 was 14.37 Cy / mm, the clarity (relative to air) was 26.18%, and the total transmittance (%) was 14.7%. Furthermore, as shown in Figure 2, the fluoroscopic image of Comparative Example 1 was not clear, and as shown in Figure 3, rainbow bands were observed under fluorescent lighting.

[0109] Comparative Example 2

[0110] A liquid crystal cell was fabricated in the same manner as in Example 1, except that the liquid crystal material was changed to a liquid crystal material (SLC127118, Slichem) with a refractive index anisotropy (Δn) of 0.093, a clearing point (Tni) of 123°C, and a Tni / (Δn)^2 value of approximately 14221.3. The MTF50 value of the liquid crystal cell of Comparative Example 2 was 43.05 Cy / mm, the clarity (relative to air) was 78.45%, and the total transmittance (%) was 12.5%. Furthermore, as shown in Figure 3, no rainbow banding occurred under fluorescent light in Comparative Example 2, but the see-through image was not clear, as shown in Figure 2. [Explanation of symbols]

[0111] 10a: First base layer 10b: 1st electrode 10c:Adhesive layer 20a: Second base layer 20b: 2nd electrode 20c: Spacer 20d: Alignment film 30: Liquid crystal layer

Claims

1. A liquid crystal composition comprising a liquid crystal material and a dichroic dye satisfying Formula 1: [Formula 1] Tni / (△n)^2≧12345.7 In Equation 1, Tni is the clearing point of the liquid crystal material, and Δn is the refractive index anisotropy of the liquid crystal material.

2. The liquid crystal composition of claim 1 , further comprising a chiral agent.

3. 2. The liquid crystal composition according to claim 1, wherein the clearing point of the liquid crystal substance is 85[deg.] C. or higher.

4. 2. The liquid crystal composition according to claim 1, wherein the refractive index anisotropy of the liquid crystal substance is 0.089 or less.

5. a first substrate, a liquid crystal layer, and a second substrate; A liquid crystal cell, wherein the liquid crystal layer comprises the liquid crystal composition according to claim 1 .

6. 6. The liquid crystal cell of claim 5, wherein the liquid crystal layer is in a twisted alignment state when no voltage is applied.

7. 7. The liquid crystal cell according to claim 6, wherein the ratio (d / p) of the thickness (d) to the pitch (p) of the liquid crystal layer in the twisted alignment state is 1 or greater.

8. The liquid crystal cell according to claim 5 , wherein the first substrate includes a first base layer and an adhesive layer, and the second substrate includes a second base layer and a spacer.

9. 9. The liquid crystal cell of claim 8, wherein the first substrate further comprises a first electrode layer between the first base layer and the adhesive layer, and the second substrate further comprises a second electrode layer between the second base layer and the spacer.

10. The liquid crystal cell according to claim 5 , wherein the first substrate does not include an alignment film, and the second substrate further includes an alignment film.

11. The liquid crystal cell according to claim 5, which satisfies the following formula: [Formula 2] A / B×100%≧80% In Equation 2, A is a modulation transfer function (MTF) 50 value measured for the liquid crystal cell when no voltage is applied, and B is a modulation transfer function (MTF) 50 value measured in air.

12. An automobile comprising: a vehicle body having one or more openings formed therein; and a liquid crystal cell according to any one of claims 5 to 11 mounted in the openings.

Images