KR20230079980A - Apparatus for supplying liquid crystal and method for manufacturing smart window - Google Patents

Abstract

This application relates to a method for manufacturing a liquid crystal supply device and a smart window. The liquid crystal supply device of the present application can suppress the phase change and weight change of the liquid crystal in the tube, and the liquid crystal supply device can be used in a method of manufacturing a smart window.

Description

Liquid crystal supply device and manufacturing method of smart window {Apparatus for supplying liquid crystal and method for manufacturing smart window}

This application relates to a method for manufacturing a liquid crystal supply device and a smart window.

A smart window is a window capable of adjusting the transmittance of light, and is also called a smart blind, an electronic curtain, a variable transmittance glass, or a dimming glass. A smart window using liquid crystal may be manufactured by injecting liquid crystal between an upper substrate and a lower substrate or through a process such as ODF (One Drop Filling).

Korean Patent Publication No. 10-2019-0052646

Liquid crystals used in smart windows are known to exhibit stable behavior in the external environment, but phase changes occur depending on the material of the tube used in the liquid crystal supply device, so they no longer maintain the characteristics of a liquid at room temperature and change to a solid. Problems can arise. In addition, a change in the weight of the liquid crystal may also appear. Occurrence of a phase change may mean that the inherent function of a liquid crystal in which an orientation is changed by an electromagnetic field is lost. The change in weight may mean that the ratio between components of a liquid crystal mixture composed of various components is changed so that the electro-optical characteristics may be changed. Therefore, the function as a smart window may be lost due to the phase change and weight change of the liquid crystal.

The present application provides a liquid crystal supply device capable of suppressing phase change and weight change of liquid crystal in a tube and a method of manufacturing a smart window using the liquid crystal supply device.

The present application includes a liquid crystal container, a liquid crystal supply pump, a first tube for moving the liquid crystal composition from the liquid crystal container to the liquid crystal supply pump, and a second tube for supplying the liquid crystal composition from the liquid crystal supply pump, and the first The tube and the second tube are each a fluorine tube.

The present application provides a method for manufacturing a smart window including supplying a liquid crystal composition using the liquid crystal supply device.

The liquid crystal supply device of the present application can suppress the phase change and weight change of the liquid crystal in the tube, and the liquid crystal supply device can be used in a method of manufacturing a smart window.

1 exemplarily shows the liquid crystal supply device of the present application.
2 shows the structure of a smart window by way of example.

1 exemplarily shows the liquid crystal supply device of the present application. As shown in FIG. 1, the liquid crystal supply device includes a liquid crystal container 100, a liquid crystal supply pump 200, a first tube 301 for moving a liquid crystal composition from the liquid crystal container to a liquid crystal supply pump, and a liquid crystal supply A second tube 302 for supplying the liquid crystal composition from the pump may be included.

The liquid crystal container 10 may contain a liquid crystal composition. The liquid crystal container 10 may be a glass container or a Teflon-coated container capable of maintaining chemical stability of the liquid crystal. The Teflon-coated container may have a Teflon-coated interior that comes into contact with the liquid crystal composition.

The liquid crystal container 10 may be filled with the liquid crystal composition 101 . The liquid crystal composition may be a liquid crystal composition.

The liquid crystal composition may include a liquid crystal compound. The type of the liquid crystal compound is not particularly limited, and a known liquid crystal compound known to be used in manufacturing a smart window may be appropriately selected and used.

In one example, the liquid crystal composition may include at least two or more types of liquid crystal compounds. Therefore, when the weight of the liquid crystal composition is changed in the tube of the liquid crystal supply device, the content between two or more types of liquid crystal compounds may be changed, so that desired electro-optical properties may not be obtained from the liquid crystal composition. According to the present application, the problem of weight change can be solved by controlling the first tube and the second tube as will be described later.

As the liquid crystal compound, a liquid crystal compound whose alignment direction can be changed by application of an external action may be used. In this specification, the term “external action” may refer to all external factors that may affect the behavior of materials included in the liquid crystal layer, such as an external voltage. Accordingly, a state without an external action may mean a state without application of an external voltage or the like.

The type and physical properties of the liquid crystal compound may be appropriately selected in consideration of the purpose of the present application. In one example, the liquid crystal compound may be a nematic liquid crystal compound or a smectic liquid crystal compound. The nematic liquid crystal may mean a liquid crystal in which rod-shaped liquid crystal molecules are arranged in parallel in the direction of the long axis of the liquid crystal molecules without regularity in position, and the smectic liquid crystal is a liquid crystal in which rod-shaped liquid crystal molecules are regularly arranged to form a layer. It may mean liquid crystals that form a structure formed and are arranged in parallel with regularity in the long axis direction.

The nematic liquid crystal compound has, for example, a clearing point of about 40°C or more, 50°C or more, 60°C or more, 70°C or more, 80°C or more, 90°C or more, 100°C or more, or about 110°C or more. Or, one having a phase transition point in the above range, that is, a phase transition point from a nematic phase to an isotropic phase may be selected. In one example, the clearing point or phase transition point may be about 160°C or less, 150°C or less, or about 140°C or less.

The liquid crystal compound may be a non-reactive liquid crystal compound. The non-reactive liquid crystal compound may mean a liquid crystal compound having no polymerizable group. As the polymerizable group, an acryloyl group, an acryloyloxy group, a methacryloyl group, a methacryloyloxy group, or an epoxy group may be exemplified.

The liquid crystal compound may have a positive or negative dielectric anisotropy. The absolute value of the dielectric anisotropy of the liquid crystal compound may be appropriately selected in consideration of the purpose of the present application. The term "dielectric constant anisotropy (Δε)" may mean a difference (ε _// - ε _⊥ ) between the horizontal permittivity (ε _// ) and the vertical permittivity (ε _⊥ ) of the liquid crystal. In this specification, the term horizontal permittivity (ε _// ) means a permittivity 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 director of the liquid crystal compound and the applied voltage are substantially horizontal, Perpendicular permittivity (ε _⊥ ) refers to a permittivity 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 caused by the director of the liquid crystal compound and the applied voltage are substantially perpendicular. The dielectric constant anisotropy of the liquid crystal molecule may be in the range of 5 to 25.

The refractive index anisotropy of the liquid crystal compound may be appropriately selected in consideration of the purpose of the present application. In this specification, the term "refractive index anisotropy" may refer to a difference between an extraordinary refractive index and an ordinary refractive index of a liquid crystal compound. The refractive index anisotropy of the liquid crystal compound may be, for example, 0.01 to 0.3. The refractive index anisotropy may be 0.01 or more, 0.05 or more, or 0.07 or more, and may be 0.3 or less, 0.2 or less, 0.15 or less, or 0.13 or less.

The liquid crystal composition may further include additives as needed. Examples of the additive include dichroic dyes and chiral agents.

When the liquid crystal composition includes a dichroic dye, it is possible to control light transmittance variable characteristics of a liquid crystal layer formed from the liquid crystal composition. In the present specification, "dye" may refer to a material capable of intensively absorbing and/or transforming light in at least a part or the entire range in the visible light region, for example, in the wavelength range of 400 nm to 700 nm, and 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.

A liquid crystal layer including a liquid crystal compound and a dichroic dye may be referred to as a guest host liquid crystal layer (GHLC layer). In the present specification, the GHLC layer (guest host liquid crystal layer) has dichroic dyes arranged together according to the arrangement of liquid crystal compounds, and anisotropic light absorption characteristics with respect to the alignment direction of the dichroic dyes and a direction perpendicular to the alignment direction, respectively It may mean a functional layer representing. For example, a dichroic dye is a substance whose light absorbance varies depending on the direction of polarization. If the absorbance of light polarized in the long-axis direction is high, it is called a p-type dye, and if the absorbance 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 direction of the major axis of the dye is absorbed and polarized light vibrating in the direction of the minor axis of the dye is less absorbed and can be transmitted. Hereinafter, it is assumed that the dichroic dye is a p-type dye unless otherwise specified.

As the dichroic dye, for example, a known dye known to have a property of being aligned according to the alignment state of a liquid crystal compound by a so-called guest host effect may be selected and used. 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, There are iketopyrrolopyrrole dyes, squaraine dyes, or pyromethene dyes, but the dyes applicable in the present application are not limited to the above.

The dichroic dye has a dichroic ratio, that is, a value obtained by dividing the absorption of polarized light parallel to the direction of the long axis of the dichroic dye by the absorption of polarized light parallel to the direction perpendicular to the direction of the long axis of the dichroic dye is 5 or more, 6 or more, or 7 or more. Dyes can be used. The dye may satisfy the dichroic ratio at at least some wavelengths or any one wavelength within a wavelength range of about 380 nm to 700 nm or about 400 nm to 700 nm, for example, within a wavelength range of the visible light region. The upper limit of the dichroic ratio may be, for example, 20 or less, 18 or less, 16 or less, or 14 or less.

The content of the dichroic dye in the liquid crystal composition may be appropriately selected in consideration of the purpose of the present application. For example, the content of the dichroic dye in the liquid crystal composition may be 0.2% by weight or more. The content of the dichroic dye may be specifically 0.5% by weight or more, 1% by weight or more, 2% by weight or more, or 3% by weight 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 in the liquid crystal layer is too small, it may be difficult to express desired transmittance characteristics, and if the content of the dichroic dye in the liquid crystal layer is too large, precipitation may occur. Therefore, it may be advantageous that the content of the dichroic dye is within the above range.

When the liquid crystal composition includes a chiral agent, a liquid crystal layer formed from the liquid crystal composition may implement a twist alignment state. The chiral agent (chiral agent or chiral dopant) may be used without any particular limitation as long as it can induce a desired twist without damaging liquid crystalline, for example, nematic regularity. A chiral agent for inducing rotation in a liquid crystal compound needs to include at least chirality in its molecular structure. Examples of the chiral agent include compounds having one or more asymmetric carbons, compounds having asymmetric points on heteroatoms such as chiral amines or chiral sulfoxides, or cumulene ) or a compound having an axially asymmetric, optically active site having an axial agent such as binaphthol. 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 such as commercially available chiral dopant liquid crystal S-811 from Merck or LC756 from BASF may be used.

The content of the chiral agent in the liquid crystal composition may be selected to achieve a desired ratio (d/p) of thickness (d) and pitch (p) in the liquid crystal layer in a twist-aligned state. The ratio (d / p) may be within the range of 0.5 or more to 20, for example. In general, the content (wt%) of the chiral agent can be calculated by the formula of 100/HTP (Helixcal Twisting power) × pitch (p) (nm). The HTP represents the helixcal twisting power of the chiral dopant, and the unit may be ㎛ ^-1 . The P may be the pitch of the liquid crystal in the twist alignment state, and the unit may be ㎛. The HTP value can be measured by a measurement method using a wedge cell. Alternatively, the HTP value may be generally provided by suppliers of the liquid crystal and the chiral dopant. The content of the chiral dopant may be determined by considering the desired pitch with reference to the above method.

The first tube 301 may serve to move the liquid crystal composition 101 filled in the liquid crystal container 100 to the liquid crystal supply pump 200 . The second tube 302 may serve to move the liquid crystal composition from the liquid crystal supply pump 200 to the smart window manufacturing facility 400 .

One end of the first tube may be contained in a liquid crystal container, and the other end of the first tube may be connected to a liquid crystal supply pump. One end of the second tube may be connected to a liquid crystal supply pump, and the other end may be exposed to supply the liquid crystal composition to a manufacturing facility of a smart window. A nozzle may be mounted on an end of the second tube not connected to a pump for supplying liquid crystal.

Each of the first tube and the second tube may be a fluorine tube. In the present specification, a fluorine tube may mean a tube formed from a fluorine-based polymer. That is, the material of the first tube and the second tube may be a fluorine-based polymer. Fluorine-based polymers may refer to polymers and/or copolymers of monomers containing fluorine. The first tube and the second tube may be formed from the same fluorine-based polymer, or may be formed from different fluorine-based polymers. According to the present application, in the liquid crystal supply process, by specifying the material of the tube directly in contact with the liquid crystal compound, it is possible to suppress the phase change and weight change of the liquid crystal in the liquid crystal supply process.

In one example, the fluorine tube may be a tube formed from a fluorine-based polymer having chemical resistance. The fluorine tube may be, for example, a tube formed from a fluorine-based polymer having chemical resistance such as Viton or PTFE (Polytetrafluoroethylene). Viton may be advantageous when flexibility is required for the first and second tubes. PTFE (Polytetrafluoroethylene) may be advantageous in terms of supplying the liquid crystal composition more stably.

In order to confirm the phase change and weight change of the liquid crystal according to the material of the tube in direct contact with the liquid crystal, evaluation was performed on tubes of various materials. A tube of the material shown in Table 1 below was prepared, and the tube was cut to a length of about 20 cm. An appropriate amount (0.3 g) of a liquid crystal composition for smart window (including three types of liquid crystal compounds) was filled into the tube. The tube filled with the liquid crystal composition was bent in a U shape to prevent leakage of the liquid crystal composition filled inside the tube, and then placed on a holder. After a certain period of time, the phase change and weight change of the liquid crystal were evaluated.

The phase change of the liquid crystal means a change from a liquid state to a solid state, and the flowability was evaluated by pressing the tube, and the state of the liquid crystal was visually confirmed by cutting the tube with a knife.

To evaluate the weight change of the liquid crystal, the weight of the tube before filling the liquid crystal (A), the weight of the tube after filling the liquid crystal (B), and the weight of the tube after a certain time elapsed after filling the liquid crystal (C) were measured. After deriving the initial weight (D) of the liquid crystal filled in the tube from (B-A), and deriving the weight change (E) of the liquid crystal filled in the tube from (C-B), the value calculated as (E / D) × 100% It was defined as the weight change of the liquid crystal. The steel level was evaluated when the weight change was about 10% or more, the medium level was evaluated when the weight change was about 2% or more and less than 10%, and the weak level was evaluated when the weight change was 1% or more and less than 2%. A change of less than 1% was evaluated as no change in weight.

In the case of tubes 1 and 3, which are silicon-based tubes, phase change began to occur immediately after filling the liquid crystal, and weight change at the level of steel was also observed. On the other hand, fluorine-based polymer tubes (Viton and PTFE) were not observed phase change and weight change even when observed on a weekly basis for 3 weeks. It is confirmed that the phase change and weight change of the liquid crystal in the tube occur when volatilization is accelerated due to a reaction between highly volatile monomolecular components in the liquid crystal composition and a material in contact with the supply device. Therefore, by selecting the material of the tube of the liquid crystal supply device as in the present invention, the phase change and weight change of the liquid crystal can be suppressed.

Material division phase change weight change silicone tube tube 1 Silicone products from Masterflex generation river level tube 2 Silicone product of KAS non-occurrence middle level tube 3 Silicone product from China (unknown maker) generation river level Tygon tube tube 4 2375 products from Saint-Gobain non-occurrence middle level tube 5 3603 product by Saint-Gobain~ non-occurrence middle level fluoride tube
(Viton) tube 6 Viton products from Masterflex non-occurrence drug level fluoride tube
(PTFE) tube 7 IXAK's PETE product non-occurrence no change in weight tube 8 PETE products of iNexus non-occurrence no change in weight

The size of the first tube 301 and the second tube 302 may be appropriately selected within a range that does not impair the purpose of the present application. In one example, the inner diameters of the first tube and the second tube may be in the range of 1.5 mm to 5 mm, respectively. In one example, each of the lengths of the first tube and the second tube may be 10 m or less. Each of the first tube and the second tube may have a length of 1 cm or more. When the size of the tube is within the above range, the liquid crystal composition can be smoothly moved, and it can be advantageous to suppress phase change and weight change of the liquid crystal composition.

The pump 200 for supplying liquid crystal may be a peristaltic pump or a metered supply device. As the metering supply device, for example, a metering pump or an ink jet can be exemplified. The peristaltic pump may be advantageous for precision liquid supply. One end of the first tube 301 and one end of the second tube 302 may be connected to a liquid crystal supply pump. By operating the pump, the liquid crystal composition in the liquid crystal container can be moved to the liquid crystal supply pump, and the liquid crystal composition can be moved from the liquid crystal supply pump to the smart window manufacturing equipment.

This application relates to a method for manufacturing a smart window using the liquid crystal supply device. In the case of manufacturing a smart window using the liquid crystal supply device of the present application, since the liquid crystal phase change and the liquid crystal change do not occur in the process of supplying the liquid crystal composition to the manufacturing facility of the smart window, the desired electro-optical characteristics of the liquid crystal composition It can be maintained, and through this, it is possible to provide a smart window with excellent performance.

2 shows the structure of the smart window by way of example. As shown in FIG. 2 , the smart window may sequentially include a first substrate 601 , a liquid crystal layer 500 and a second substrate 602 . A configuration including the first substrate 601, the liquid crystal layer 500, and the second substrate 602 may be referred to as a liquid crystal cell. The liquid crystal layer may be formed from a liquid crystal composition supplied from a liquid crystal supply device.

In one example, the manufacturing method of the smart window may include dropping a liquid crystal composition on a first substrate by the liquid crystal supply device and bonding a second substrate onto the first substrate.

In another example, the manufacturing method of the smart window may include injecting a liquid crystal composition between a first substrate and a second substrate by the liquid crystal supply device.

The first substrate may include a first base layer and a first electrode layer. The first electrode layer may be formed on one surface of the first base layer. The second substrate may include a second substrate layer and a second electrode layer. The second electrode layer may be formed on one side of the second base layer.

In one example, each of the first base layer and the second base layer may be a polymer film in terms of implementation of a flexible device. As the polymer film, TAC (triacetyl cellulose); COP (cyclo olefin copolymer), such as a norbornene derivative; 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); PAR (polyarylate) or amorphous fluororesin, etc. may be used, but are not limited thereto. 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 first base layer and the second base layer, if necessary.

The first electrode layer and the second electrode layer may perform a role of applying an external action, for example, an electric field, so that a material included in the liquid crystal layer transmits or blocks incident light. In one example, the first electrode layer and/or the second electrode layer may include a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as indium tin oxide (ITO), but is not limited thereto. The upper and/or lower second electrode layers may be formed by depositing, for example, a metal oxide such as the conductive polymer, conductive metal, conductive nanowire, or indium tin oxide (ITO).

The first substrate may further include a first alignment layer formed on one surface of the first electrode layer. The second substrate may further include a second alignment layer formed on one surface of the second electrode layer.

The first alignment layer and/or the second alignment layer may be a photo alignment layer or a rubbing alignment layer. The first alignment layer and/or the second alignment layer include a polyimide compound, a poly(vinyl alcohol) compound, a poly(amic acid) compound, a polystyrene compound, a polyamide ( Materials known to exhibit orientation ability by rubbing orientation, such as polyamide compounds and polyoxyethylene compounds, polyimide compounds, polyamic acid compounds, polynorbornene compounds, Phenylmaleimide copolymer compound, polyvinylcinnamate compound, polyazobenzene compound, polyethyleneimide compound, polyvinylalcohol compound, polyamide compound, polyethylene (polyethylene) compound, polystylene compound, polyphenylenephthalamide compound, polyester compound, CMPI (chloromethylated polyimide) compound, PVCI (polyvinylcinnamate) compound and polymethyl methacrylate ) compound and the like, but may include one or more selected from the group consisting of materials known to exhibit alignment ability by light irradiation, but are not limited thereto.

The first alignment layer and/or the second alignment layer may be in contact with the liquid crystal layer. The first alignment layer and/or the second alignment layer may be a vertical alignment layer or a horizontal alignment layer. In this specification, the "horizontal alignment layer" may refer to a layer including an alignment material that imparts a horizontal alignment force to a liquid crystal compound present in an adjacent liquid crystal layer. In the present specification, the “vertical alignment layer” may refer to a layer including an alignment material that imparts a vertical alignment force to liquid crystal compounds present in an adjacent liquid crystal layer. The pretilt angle of adjacent liquid crystal compounds with respect to the vertical alignment layer may be in the range of 80 degrees to 90 degrees, 85 degrees to 90 degrees, or about 87 degrees to 90 degrees, and the pretilt angle of adjacent liquid crystal compounds with respect to the horizontal alignment layer is 0 degrees to 10 degrees, 0 degrees to 5 degrees, or 0 degrees to 3 degrees.

The smart window may further include a spacer maintaining a distance between the first substrate and the second substrate. The spacer may be formed between the electrode layer and the alignment layer or on the alignment layer in one of the first substrate and the second substrate.

The spacer may have a ball shape, column shape, or barrier rib shape. When the spacer has a barrier rib shape, it may be advantageous in terms of maintaining the height of the liquid crystal cell and improving physical rigidity of the liquid crystal cell. The barrier rib may partition a space between the lower substrate and the upper substrate into two or more spaces.

The spacer may include a curable resin. The type of curable resin is not particularly limited, and for example, a thermosetting resin or a photocurable resin, such as an ultraviolet curable resin, may be used. Examples of the thermosetting resin include, but are not limited to, silicone resins, silicon resins, fran resins, polyurethane resins, epoxy resins, amino resins, phenol resins, urea resins, polyester resins, or melamine resins. . UV curable resins are typically acrylic polymers such as polyester acrylate polymers, polystyrene acrylate polymers, epoxy acrylate polymers, polyurethane acrylate polymers or polybutadiene acrylate polymers, silicone acrylate polymers or alkyl acrylates. Polymers and the like can be used, but are not limited thereto.

The liquid crystal layer may switch an alignment state according to an applied voltage. In one example, the liquid crystal layer may have a first alignment state when voltage is not applied to the liquid crystal layer, and the liquid crystal layer may have a second alignment state different from the first alignment state when voltage is applied to the liquid crystal layer. can have As the first alignment state and/or the second alignment state, a horizontal orientation state, a vertical orientation state, a twist orientation state, an inclined orientation state, a hybrid orientation state, and the like may be exemplified.

In this specification, the "horizontal alignment state" is a state in which the directors of the liquid crystal compounds in the liquid crystal layer are arranged substantially parallel to the plane of the liquid crystal layer. For example, the angle formed by the director with respect to the plane of the liquid crystal layer is For example, it may be in the range of about -10 degrees to 10 degrees or -5 degrees to 5 degrees, or about 0 degrees.

In this specification, the "vertical alignment state" is a state in which the directors of the liquid crystal compounds in the liquid crystal layer are arranged substantially perpendicular to the plane of the liquid crystal layer, and, for example, the angle formed by the director 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 it may form about 90 degrees.

In this specification, the “twist alignment state” may mean a spiral structure in which directors of liquid crystal compounds are twisted along a virtual helical axis in a liquid crystal layer and aligned while forming layers. The twist alignment state may be implemented in a vertical, horizontal or inclined alignment state, that is, the vertical twist alignment mode is a state in which individual liquid crystal compounds are vertically aligned while twisting along a helical axis to form layers, and horizontal twist alignment The mode is a state in which individual liquid crystal compounds are horizontally aligned and twisted along the helical axis to form layers, and the oblique twist alignment mode is a state in which individual liquid crystal compounds are twisted along the helical axis in an obliquely aligned state to form layers.

In this specification, “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 a liquid crystal layer with respect to a plane of the liquid crystal layer, gradually increases or decreases along the thickness direction of the liquid crystal layer.

The thickness of the liquid crystal layer is not particularly limited, and for example, the thickness of the liquid crystal layer is 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, or 2.5 μm or more. ㎛ 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, 8 μm or more, 8.5 μm or more , may be 9 μm or more or 9.5 μm or more. The upper limit of the thickness of the liquid crystal layer is not particularly limited, and may be generally about 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

A driving mode of the liquid crystal cell may be appropriately selected as needed. Examples of the driving modes of the liquid crystal cell include ECB (Electrically Controlled Birefringence) mode, TN (Twisted Nematic) mode, STN (Super Twisted Nematic) mode, RTN (Reverse Twisted Nematic) mode, and RSTN (Reverse Super Twisted Nematic) mode. , HAN (Hybrid Aligned Nematic) mode, Twisted HAN (Twisted Hybrid Aligned Nematic) mode, Super twisted HAN (Super Twisted Hybrid Aligned Nematic) mode, IPS (In-Plane Switching) mode, VA (vertical alignment) mode, etc. Depending on the desired driving mode of the liquid crystal cell, the type of liquid crystal, the type of alignment layer, the type of additive, etc. may be appropriately selected.

The smart window may switch between at least two states having different permeability. In one example, a smart window can be a device that can switch between a transmissive and obstructive mode state.

The smart window in the transmission mode has a transmittance of at least 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more. It may be about 60% or more, 65% or more, 70% or more, 75% or more, or 80% or more. Transmittance in the transmission mode may be 100% or less, 95% or less, 90% or less, or 85% or less in another example. However, since higher transmittance in the transmission mode is more advantageous, the upper limit is not particularly limited.

In the blocking mode, the transmittance of the smart window is 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, It may be 10% or less or 5% or less. Transmittance in the blocking mode may be about 0% or more, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more in another example. However, since lower transmittance is more advantageous in the blocking mode, the lower limit of the transmittance in the blocking mode state is not particularly limited.

The transmittance may be, for example, straight light transmittance. The straight light transmittance is a percentage of the ratio of the light incident in the smart window to the light transmitted in the same direction as the incident direction. For example, if the smart window is in the form of a film or sheet, the percentage of light transmitted through the smart window in a direction parallel to the normal line among light incident in a direction parallel to the normal direction of the surface of the film or sheet is referred to as the transmittance. can be defined

The transmittance is, for example, the transmittance for any one wavelength within the range of about 400 to 700 nm or about 380 to 780 nm, the transmittance for the entire visible light region, or the transmittance for the entire visible light region. It may be a maximum or minimum transmittance, or an average value of transmittance in the visible light region.

The smart window may include additional components other than the liquid crystal cell, if necessary. That is, depending on the driving mode, switching between the transmission mode and the blocking mode described above is possible with the liquid crystal cell alone, but additional configurations may be included to facilitate implementation or switching of these modes.

In one example, the smart window may further include a polarizer (passive polarizer) disposed on one side or both sides of the liquid crystal cell. In one example, the smart window may sequentially include a first polarizer, a liquid crystal cell, and a second polarizer. The first and/or second polarizers may be attached to the liquid crystal cell through an adhesive or a pressure-sensitive adhesive. As the adhesive or pressure-sensitive adhesive, for example, an acrylic, epoxy-based, silicone-based, epoxy-based, or urethane acrylate-based adhesive or pressure-sensitive adhesive may be used.

In this specification, the term polarizer refers to a film, sheet, or device having a polarization function. A polarizer is a functional element capable of extracting light vibrating in one direction from incident light vibrating in several directions.

The polarizer may be an absorption type polarizer or a reflection type polarizer. In this specification, an absorption type polarizer refers to an element that exhibits selective transmission and absorption characteristics with respect to incident light. For example, the absorption type polarizer may transmit light vibrating in one direction from incident light vibrating in several directions and absorb light vibrating in the other direction. A reflective polarizer refers to an element that exhibits selective transmission and reflection characteristics with respect to incident light. For example, the reflective polarizer may transmit light vibrating in one direction from incident light vibrating in several directions and reflect light vibrating in the other direction.

As the absorption type polarizer, for example, polarizing paper in which iodine is dyed on a polymer stretched film such as a PVA (poly(vinyl alcohol)) stretched film or a liquid crystal polymerized in an aligned state is used as a host, and the liquid crystal is aligned. A guest-host type polarizer using a dichroic dye arranged according to a guest as a guest may be used, but is not limited thereto. As the reflection type polarizer, for example, a reflection type polarizer known as DBEF (Dual Brightness Enhancement Film) or a reflection type polarizer formed by coating a liquid crystal compound such as LLC (Lyotropic liquid crystal) may be used. It is not limited thereto.

The polarizer may be a linear polarizer. In this specification, a linear polarizer means a case in which selectively transmitted light is linearly polarized light vibrating in one direction and selectively absorbed or reflected light is linearly polarized light vibrating in a direction perpendicular to the vibrational direction of the linearly polarized light. In the case of an absorption-type linear polarizer, a light transmission axis and a light absorption axis may be perpendicular to each other. In the case of a reflective linear polarizer, a light transmission axis and a light reflection axis may be perpendicular to each other.

A protective film, an antireflection film, a retardation film, an adhesive layer, an adhesive layer, a surface treatment layer, and the like may be additionally formed on one side or both sides of the polarizer, respectively. The retardation film may be, for example, a polymer stretched film or a liquid crystal polymerization film.

The transmittance of the polarizer to light having a wavelength of 550 nm may be in the range of 40% to 50%, respectively. Transmittance may mean single transmittance of a polarizer for light having a wavelength of 550 nm. The single transmittance of the polarizer can be measured using, for example, a spectrometer (V7100, manufactured by Jasco). For example, air is set as the base line while the polarizer sample (without upper and lower protective films) is mounted on the device, and each transmittance is measured with the axis of the polarizer sample aligned vertically and horizontally with the axis of the reference polarizer. After measuring, the single transmittance can be calculated.

In one example, a transmission axis of the first polarizer and a transmission axis of the second polarizer may be orthogonal to each other. Specifically, the angle between the transmission axes of the first polarizer and the second polarizer may be about 80 degrees to about 100 degrees, about 85 degrees to about 95 degrees, or about 90 degrees (orthogonal polarizer).

The smart window may be applied to a variety of uses, including various architectural or vehicle materials requiring transmittance adjustment, or eyewear such as goggles, sunglasses, or helmets for augmented reality experiences or sports. In one example, the smart window itself may be a vehicle sunroof. For example, in an automobile including a body in which at least one opening is formed, the smart window mounted on the opening may be mounted and used.

100: liquid crystal container, 101: liquid crystal composition, 200: liquid crystal supply pump, 301: first tube, 302: second tube, 400: smart window manufacturing equipment, 500: liquid crystal layer, 601: first substrate, 602: first 2 board

Claims (11)

A liquid crystal container, a liquid crystal supply pump, a first tube for moving the liquid crystal composition from the liquid crystal container to the liquid crystal supply pump, and a second tube for supplying the liquid crystal composition from the liquid crystal supply pump, wherein the first tube and the first tube A liquid crystal supply device in which each of the two tubes is a fluorine tube. The liquid crystal supply device according to claim 1, wherein the liquid crystal container is filled with a liquid crystal composition. The liquid crystal supply device according to claim 1, wherein the liquid crystal container is a glass container or a Teflon-coated container. The liquid crystal supply device according to claim 1, wherein one end of the first tube and one end of the second tube are connected to a liquid crystal supply pump. The liquid crystal supply device according to claim 1, wherein the fluorine tube is a tube formed from a fluorine-based polymer having chemical resistance. The liquid crystal supply device according to claim 1, wherein the fluorine tube is a tube formed from Viton or Polytetrafluoroethylene (PTFE). The liquid crystal supply device according to claim 1, wherein the inner diameters of the first tube and the second tube are in the range of 1.5 mm to 5 mm, respectively. The liquid crystal supply device according to claim 1, wherein each of the first tube and the second tube has a length ranging from 1 cm to 10 m. The liquid crystal supply device according to claim 1, wherein the pump for supplying the liquid crystal is a peristaltic pump or a metered supply device. A method of manufacturing a smart window comprising the steps of dropping a liquid crystal composition on a first substrate by the liquid crystal supply device of claim 1 and bonding a second substrate onto the first substrate. The method of claim 10 , wherein the first substrate includes a first substrate layer and a first electrode layer, and the second substrate includes a second substrate layer and a second electrode layer.

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