Optical laminate and smart window including the same

Abstract

The present invention relates to a variable transmittance optical stack including a first polarizer; a first electrode layer formed on one surface of the first polarizer; a second polarizer facing the first polarizer; a second electrode layer formed on one surface of the second polarizer and facing the first electrode layer; and a liquid crystal layer provided between the first electrode layer and the second electrode layer, wherein at least one of the first electrode layer and the second electrode layer is formed in direct contact with one of the first polarizer and the second polarizer, the first electrode layer including a plurality of first unit electrodes arranged in a first direction, and the second electrode layer including a plurality of second unit electrodes arranged in a second direction, and a smart window including the same.

Description

[Technical Field]

[0001] The present invention relates to a variable transmittance optical stack and a smart window including the same. [Background technology]

[0002] Generally, glass windows of vehicles such as cars are often coated with an external light blocking coating. However, conventional glass windows of vehicles have a fixed transmittance, and the external light blocking coating also has a fixed transmittance. Therefore, the overall transmittance of such conventional vehicle windows is fixed, which can lead to accidents. For example, if the overall transmittance is set low, there is no problem during the day when there is sufficient surrounding light. However, there is a problem that drivers have difficulty properly checking the surroundings of the vehicle when there is insufficient surrounding light, such as at night. Alternatively, if the overall transmittance is set high, there is a problem that drivers may experience glare during the day when there is sufficient surrounding light. For this reason, a variable transmittance optical laminate has been developed that can change light transmittance when a voltage is applied.

[0003] The variable transmittance optical stack is driven by applying a voltage to drive the liquid crystal to change the transmittance. The variable transmittance optical stack developed to date has been manufactured by forming an electrode layer for driving the liquid crystal on a separate substrate, combining this with other elements such as a polarizer, and integrally patterning each electrode layer for driving the liquid crystal.

[0004] For example, Japanese Patent Publication No. 2018-010035 also discloses a variable transmittance optical laminate including an electrode layer formed by patterning integrally on a polycarbonate (PC) substrate having a predetermined thickness.

[0005] However, when a separate substrate is used to form the electrode layer, the manufacturing process becomes complicated, which increases manufacturing costs. In addition, the thickness of the laminate increases, which causes a phase difference and thus changes the transmittance.

[0006] Furthermore, when the electrode layers for driving the liquid crystal are integrally formed, it is possible to apply or not apply a driving voltage to only the entire region of the liquid crystal layer, and there is a problem that divided driving is not possible for some regions.

[0007] Therefore, there is a need to develop a variable transmittance optical stack that does not include a separate substrate for forming an electrode layer, thereby simplifying the manufacturing process and reducing the thickness, and that is capable of separately driving certain regions of the liquid crystal layer. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide a variable transmittance optical laminate that includes a plurality of divided driving regions, thereby enabling the implementation of various modes.

[0009] Another object of the present invention is to provide a variable transmittance optical laminate that can be produced by a simpler process.

[0010] Another object of the present invention is to provide a variable transmittance optical laminate with a reduced thickness.

[0011] Another object of the present invention is to provide a variable transmittance optical laminate having improved transmittance in the light transmission mode.

[0012] Another object of the present invention is to provide a smart window including the variable transmittance optical laminate, and a means of transportation, a wearable device, or a building fixture to which the smart window is applied.

[0013] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0014] The present invention relates to a variable transmittance optical stack including: a first polarizer; a first electrode layer formed on one surface of the first polarizer; a second polarizer facing the first polarizer; a second electrode layer formed on one surface of the second polarizer and facing the first electrode layer; and a liquid crystal layer provided between the first electrode layer and the second electrode layer, wherein at least one of the first electrode layer and the second electrode layer is formed in direct contact with one of the first polarizer and the second polarizer, the first electrode layer including a plurality of first unit electrodes arranged in a first direction, and the second electrode layer including a plurality of second unit electrodes arranged in a second direction.

[0015] In the first aspect of the present invention, the unit electrodes may be formed in a stripe shape and spaced apart from each other.

[0016] In the second aspect of the present invention, the first unit electrode and the second unit electrode may be arranged so as to be perpendicular to each other.

[0017] In the third aspect of the present invention, the interval between the unit electrodes may be 30 to 100 μm.

[0018] In a fourth aspect of the present invention, the variable transmittance optical laminate may achieve maximum transmittance and minimum transmittance at a driving voltage of 10V or less.

[0019] In a fifth aspect of the present invention, the maximum transmittance may be from 35% to 45%.

[0020] In a sixth aspect of the present invention, the minimum transmittance may be from 0% to 3%.

[0021] In a seventh aspect, the present invention may further include a drive circuit section for applying individual drive voltages to the unit electrodes.

[0022] In an eighth aspect of the present invention, at least one of the first electrode layer and the second electrode layer may include one or more selected from the group consisting of transparent conductive oxides, metals, carbon-based materials, conductive polymers, conductive inks, and nanowires.

[0023] In a ninth aspect of the present invention, at least one of the first polarizing plate and the second polarizing plate may have a thickness of 30 to 200 μm.

[0024] In a tenth aspect of the present invention, the liquid crystal layer may include one or more spacers selected from the group consisting of ball spacers and column spacers.

[0025] In an eleventh aspect of the present invention, the spacer may have a height of 1 to 10 μm.

[0026] In a twelfth aspect of the present invention, the area occupied by the spacer in the liquid crystal layer may be 0.01% to 10% of the area of ​​the liquid crystal layer.

[0027] In a thirteenth aspect of the present invention, the variable transmittance optical laminate may further include one or more layers selected from the group consisting of an overcoat layer, an adhesive layer, an ultraviolet absorbing layer, and a hard coating layer.

[0028] The present invention also relates to a smart window including the variable transmittance optical laminate.

[0029] The present invention also relates to a means of transportation including said smart window.

[0030] The present invention also relates to a vehicle in which the smart window is applied to at least one of a front window, a rear window, a side window, a sunroof window, and an interior partition.

[0031] The present invention also relates to a wearable device including the smart window.

[0032] The present invention also relates to architectural fittings including the smart window. [Effects of the Invention]

[0033] The variable transmittance optical stack according to the present invention includes a plurality of divided driving regions, thereby enabling various modes to be realized compared to conventional optical stacks. Specifically, when a voltage is applied to the electrode layer, the unit cells can be driven individually, thereby selectively driving only a desired unit region.

[0034] In addition, according to another variable transmittance optical laminate of the present invention, an electrode layer is formed directly on one side of a polarizer, and a separate substrate for forming the electrode layer is not required. This simplifies the manufacturing process compared to conventional optical laminates, significantly reduces the thickness, and may further improve the transmittance in the transmission mode. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 is a diagram showing a layer structure of a variable transmittance optical layered body according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram for explaining the driving mode of the variable transmittance optical laminate of the present invention. [Figure 3] FIG. 3 is a diagram for explaining the driving mode of the variable transmittance optical laminate of the present invention. [Figure 4] FIG. 4 is a diagram for explaining the driving mode of the variable transmittance optical laminate of the present invention. [Figure 5] FIG. 5 is a diagram for explaining the driving mode of the variable transmittance optical laminate of the present invention. [Figure 6] FIG. 6 is a graph showing the transmittance of each unit cell of the optical laminate manufactured according to the manufacturing example of the present invention as a function of the driving voltage. DETAILED DESCRIPTION OF THE INVENTION

[0036] The present invention relates to a variable transmittance optical stack that includes a plurality of unit electrodes to which individual driving voltages are applied, thereby enabling selective driving of only desired unit regions, thereby enabling the realization of various modes, and that has an improved transmittance in a transmission mode due to a reduced thickness of the stack achieved by directly forming an electrode layer for driving a liquid crystal layer on one side of a polarizer.

[0037] More specifically, the present invention relates to a variable transmittance optical stack including: a first polarizer; a first electrode layer formed on one surface of the first polarizer; a second polarizer facing the first polarizer; a second electrode layer formed on one surface of the second polarizer and facing the first electrode layer; and a liquid crystal layer provided between the first electrode layer and the second electrode layer, wherein at least one of the first electrode layer and the second electrode layer is formed in direct contact with one of the first polarizer and the second polarizer, the first electrode layer including a plurality of first unit electrodes arranged in a first direction, and the second electrode layer including a plurality of second unit electrodes arranged in a second direction.

[0038] The variable transmittance optical laminate of the present invention is particularly suitable for technical fields in which light transmittance can be changed by applying a voltage, and may be used, for example, in smart windows.

[0039] A smart window is an optical structure that controls the amount of light or heat passing through by changing its light transmittance in response to the application of an electrical signal. That is, a smart window can be changed between transparent, opaque, or translucent depending on the voltage applied, and is also called variable transmittance glass, light-control glass, or smart glass.

[0040] Smart windows can be used to divide the interior space of vehicles and buildings or as partitions for privacy, or as light windows placed in openings in buildings. They can also be used for highway signs, bulletin boards, odometers, clocks, or advertising screens, and can be used to replace glass in vehicles such as windows or sunroofs in automobiles, buses, airplanes, ships, or trains.

[0041] The variable transmittance optical laminate of the present invention can also be used in smart windows in the various technical fields mentioned above. Since the electrode layer is formed directly on the polarizer, a separate substrate for forming the electrode layer is not required, resulting in a thin, advantageous flexible structure. The inclusion of multiple unit electrodes enables various modes to be realized, making the variable transmittance optical laminate particularly suitable for smart windows for vehicles or buildings. In one or more embodiments, a smart window using the variable transmittance optical laminate of the present invention can be used in transportation, such as the front, rear, side, and sunroof windows of automobiles, or building fixtures. In addition to applications for blocking external light, the smart window can also be used for dividing interior spaces such as automobiles or buildings, such as interior partitions, or for privacy purposes. It can also be used in wearable devices such as helmets, glasses, and watches.

[0042] Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. However, the following drawings attached to this specification are intended to illustrate preferred embodiments of the present invention and, together with the above-described invention content, serve to further understand the technical concept of the present invention, and therefore the present invention should not be interpreted as being limited only to the matters depicted in these drawings.

[0043] The terms used herein are for the purpose of describing the embodiments and are not intended to limit the present invention. In this specification, the singular form includes the plural form unless otherwise specified. For example, the term "polarizer" used herein may refer to at least one of the first and second polarizers, and the term "electrode layer" may refer to at least one of the first and second electrode layers.

[0044] As used herein, the terms "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, operations and / or elements other than the stated components, steps, operations and / or elements. Like reference numerals refer to like elements throughout the specification.

[0045] Spatially relative terms such as "below," "bottom," "lower," "upper," "top," "top," and the like may be used to easily describe the relationship of one element or component to another, as illustrated in the figures. Spatially relative terms should be understood to encompass different orientations of elements in use or operation in addition to the orientation depicted in the figures. For example, if an element depicted in the figures is inverted, an element described as "below" or "below" another element may also be positioned "above" the other element. Thus, the exemplary term "below" may encompass both an orientation of below and above. Elements may be oriented in other directions, and thus the spatially relative terms may be interpreted accordingly.

[0046] As used herein, the "planar direction" can be interpreted as the normal direction of the polarizer and / or electrode layer, ie, the direction seen from the user's viewing side.

[0047] As used in this specification, "substantially" can be interpreted not only to mean being completely identical or identical physically, but also to mean being within the range of error in measurement or manufacturing processes, for example, being within the range of error of 5% or less.

[0048] FIG. 1 is a diagram showing a layer structure of a variable transmittance optical layered body according to an embodiment of the present invention.

[0049] Referring to FIG. 1, a variable transmittance optical stack according to one embodiment of the present invention may include a first polarizer 110, a second polarizer 120, a first electrode layer 210, a second electrode layer 220, and a liquid crystal layer 300.

[0050] The polarizing plates 110 and 120 include polarizers that perform a polarizing function, and may include a protective film according to the needs of users.

[0051] The polarizer may be a conventional or later developed polarizer, such as a stretched polarizer or a coated polarizer.

[0052] In one embodiment, the stretched polarizer may include a stretched polyvinyl alcohol (PVA)-based resin. The polyvinyl alcohol (PVA)-based resin may be a polyvinyl alcohol-based resin obtained by saponifying a polyvinyl acetate-based resin. Examples of polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other monomers copolymerizable therewith. The other monomers may be unsaturated carboxylic acid-based, unsaturated sulfonic acid-based, olefin-based, vinyl ether-based, or acrylamide-based monomers having an ammonium group. The polyvinyl alcohol (PVA)-based resin may also be modified, such as polyvinyl formal or polyvinyl acetal modified with aldehydes.

[0053] In one embodiment, the coating type polarizer may be formed using a liquid crystal coating composition, which may include a reactive liquid crystal compound and a dichroic dye.

[0054] The reactive liquid crystal compound may refer to a compound that includes, for example, a mesogen skeleton and one or more polymerizable functional groups. Such reactive liquid crystal compounds are known in various ways as reactive mesogens (RMs). The reactive liquid crystal compound can be polymerized by light or heat to form a cured film in which a polymer network is formed while maintaining the liquid crystal alignment.

[0055] The reactive liquid crystal compound may be a monofunctional or polyfunctional reactive liquid crystal compound. The monofunctional reactive liquid crystal compound is a compound having one polymerizable functional group, and the polyfunctional reactive liquid crystal compound is a compound having two or more polymerizable functional groups.

[0056] The dichroic dye is a component contained in the liquid crystal coating composition that imparts polarization properties and has different absorbance in the long axis direction and the short axis direction of the molecule. The dichroic dye may be any conventional or later-developed dichroic dye, for example, one or more selected from the group consisting of azo dyes, anthraquinone dyes, perylene dyes, merocyanine dyes, azomethine dyes, phthaloperylene dyes, indigo dyes, dioxazine dyes, polythiophene dyes, and phenoxazine dyes.

[0057] The liquid crystal coating composition may further include a solvent capable of dissolving the reactive liquid crystal compound and the dichroic dye, such as propylene glycol monomethyl ether acetate (PGMEA), methyl ethyl ketone (MEK), xylene, chloroform, etc. The liquid crystal coating composition may further include a leveling agent, a polymerization initiator, etc., within a range that does not impair the polarization properties of the coating film.

[0058] The protective film may be provided to protect the polarization properties of the polarizer from post-processing and external environments.

[0059] The protective film may be formed on one or both sides of the polarizer in direct contact therewith, but is not limited thereto, and may be formed on other components included in the polarizing plate to form the polarizing plate.

[0060] In one or more embodiments, the protective film may include one or more selected from the group consisting of polyethylene terephthalate (PET), polyethylene isophthalate (PEI), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), diacetyl cellulose, triacetyl cellulose (TAC), polycarbonate (PC), polyethylene (PE), polypropylene (PP), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyethyl acrylate (PEA), polyethyl methacrylate (PEMA), and cyclic olefin polymer (COP).

[0061] In other embodiments, the polarizers 110 and 120 may further include other components in addition to the above-mentioned components to supplement or enhance the properties of the polarizer. For example, the polarizers may include a phase difference adjusting layer or a refractive index adjusting layer to improve the optical properties of the polarizers, or an overcoat layer to further improve the mechanical durability of the polarizers.

[0062] The retardation control layer complements the optical properties of the optical laminate and may be implemented in the form of a retardation film, etc., and may be a conventional or later-developed retardation film, etc. For example, a quarter-wave plate (1 / 4 wave plate) or a half-wave plate (1 / 2 wave plate) for delaying the phase of light may be used, and these may be used alone or in combination.

[0063] The retardation adjusting layer may be formed in direct contact with one surface of the polarizer in place of a protective film, but is not limited thereto. For example, the retardation adjusting layer may be formed on one surface of the protective film or on one surface of the refractive index adjusting layer.

[0064] The retardation adjusting layer may be a polymer stretched film obtained by stretching a polymer film that can be given optical anisotropy by stretching in an appropriate manner, or a liquid crystal polymer film.

[0065] In one embodiment, the polymer stretched film may be a polymer layer containing polyolefins such as polyethylene (PE) or polypropylene (PP), cycloolefin polymers (COP) such as polynorbornene, polyesters such as polyvinyl chloride (PVC), polyacrylonitrile (PAN), polysulfone (PSU), acrylic resins, polycarbonate (PC), and polyethylene terephthalate (PET), polyacrylate, cellulose ester polymers such as polyvinyl alcohol (PVA), and triacetyl cellulose (TAC), or a copolymer of two or more monomers among the monomers forming the polymers.

[0066] The method for obtaining the stretched polymer film is not particularly limited, and can be, for example, by molding the polymer material into a film and then stretching it. The film-forming method is not particularly limited, and can be formed into a film by known methods such as injection molding, sheet molding, blow molding, injection blow molding, inflation molding, extrusion molding, foam molding, and cast molding. Secondary processing methods such as compressed air molding and vacuum forming can also be used. Among these, extrusion molding and cast molding are preferred. In this case, for example, an unstretched film can be extruded using an extruder equipped with a T-die, a circular die, or the like. When obtaining a molded product by extrusion molding, a material in which various resin components, additives, etc. have been melt-kneaded in advance can be used, or the product can be formed through melt-kneading during extrusion molding. Alternatively, an unstretched film can be cast-molded by dissolving various resin components in a solvent common to the various resin components, such as chloroform or methylene dichloride, followed by casting, drying, and solidification.

[0067] The polymer stretched film may be produced by uniaxially stretching the formed film in the mechanical direction (MD; machine direction, lengthwise or longitudinal direction) or uniaxially stretching the formed film in the transverse direction (TD; widthwise or transverse direction) of the mechanical direction. Alternatively, a biaxially stretched film may be produced by stretching the formed film using a method such as sequential biaxial stretching with roll stretching and tenter stretching, simultaneous biaxial stretching with tenter stretching, or biaxial stretching with tubular stretching.

[0068] The liquid crystal polymer film may include a reactive liquid crystal compound in a polymerized state. The reactive liquid crystal compound may be the same as the reactive liquid crystal compound of the coating-type polarizer described above.

[0069] In one or more embodiments, the thickness of the retardation adjusting layer may be 10 to 100 μm in the case of a polymer stretched film, and 0.1 to 5 μm in the case of a liquid crystal polymer film.

[0070] The refractive index adjustment layer may be provided to compensate for a refractive index difference of the optical laminate caused by the electrode layer and may serve to improve visibility by reducing the refractive index difference. The refractive index adjustment layer may also be provided to correct a color caused by the electrode layer. In particular, the electrode layer may be formed to have a plurality of unit electrodes, as described below. In this case, the refractive index adjustment layer may compensate for a transmittance difference between a patterned region where the pattern is formed and a non-patterned region where the pattern is not formed.

[0071] Specifically, when the electrode layer is stacked adjacent to another member (e.g., a polarizer) having a different refractive index from the electrode layer, the difference in refractive index between the adjacent layers may cause a difference in light transmittance, and in particular, when a pattern is formed on the electrode layer, the patterned region and the non-patterned region may be visually distinguishable. Therefore, by including the refractive index control layer, the refractive index is compensated for, thereby reducing the difference in light transmittance of the optical stack, and in particular, when a pattern is formed on the electrode layer, the patterned region and the non-patterned region may be visually distinguishable.

[0072] In one embodiment, the refractive index of the refractive index-adjusting layer may be appropriately selected depending on the material of the adjacent member, and is preferably 1.4 to 2.6, and more preferably 1.4 to 2.4, in order to prevent light loss due to a sharp difference in refractive index between the electrode layer and the member such as the polarizer.

[0073] The refractive index adjusting layer is not particularly limited as long as it can prevent a sharp difference in refractive index between the electrode layer and other components such as a polarizer, and may be formed from a compound used to form a conventional or later-developed refractive index adjusting layer, for example, a refractive index adjusting layer-forming composition containing a polymerizable isocyanurate compound.

[0074] In one or more embodiments, the polarizing plates 110 and 120 may have a thickness of 30 to 200 μm, preferably 30 to 170 μm, and more preferably 50 to 150 μm, which allows the polarizing plates to maintain their optical properties and allows for the manufacture of a thin optical laminate.

[0075] The electrode layers 210 and 220 are provided to drive the liquid crystal layer 300 and may be formed in direct contact with the polarizers 110 and 120. For example, as shown in FIG. 1, the first electrode layer 210 and the second electrode layer 220 may be formed in direct contact with the first polarizer 110 and the second polarizer 120, respectively.

[0076] Conventional light-control laminates used in the manufacture of smart windows, etc., are manufactured by forming an electrode layer for driving liquid crystal on one side of the laminate and laminating the other side with a polarizer. However, the variable transmittance optical laminate according to the present invention does not include a separate substrate for forming the electrode layer, and instead forms the electrode layer directly on one side of the polarizer, thereby reducing the thickness of the laminate and improving the transmittance and bending characteristics in the transmission mode.

[0077] In one embodiment, the electrode layers 210 and 220 may be formed by direct deposition on one surface of the polarizers 110 and 120. In this case, the electrode layers 210 and 220 may be formed by directly contacting the pre-treated surface of the polarizers 110 and 120 after pre-treating one surface of the polarizers 110 and 120 with a corona treatment or plasma treatment to improve adhesion to the polarizers 110 and 120. The pre-treatment is not limited to a corona treatment or a plasma treatment, and any conventional or later-developed pre-treatment process may be used within the scope of the present invention.

[0078] In another embodiment, the electrode layers 210 and 220 may be formed in direct contact with the polarizers 110 and 120, with an easy-adhesion layer (not shown) provided on one side of the polarizers 110 and 120 sandwiched therebetween to improve adhesion to the polarizers 110 and 120.

[0079] The electrode layers 210 and 220 may have a visible light transmittance of 50% or more, preferably 60% or more, and may include, for example, one or more selected from the group consisting of transparent conductive oxides, metals, carbon-based materials, conductive polymers, conductive inks, and nanowires, but are not limited thereto, and conventional or later-developed electrode layer materials may be used.

[0080] In one or more embodiments, the transparent conductive oxide may include one or more selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), fluorine tin oxide (FTO), zinc oxide (ZnO), etc. The metal may include one or more selected from the group consisting of gold (Au), silver (Ag), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), chromium (Cr), titanium (Ti), tungsten (W), niobium (Nb), tantalum (Ta), vanadium (V), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), and alloys containing at least one of these metals, such as a silver-palladium-copper (APC) alloy or a copper-calcium (CuCa) alloy. The carbon-based material may include one or more selected from the group consisting of carbon nanotubes (CNTs) and graphene, and the conductive polymer may include one or more selected from the group consisting of polypyrrole, polythiophene, polyacetylene, PEDOT, and polyaniline. The conductive ink may be an ink containing a metal powder and a curable polymer binder, and the nanowires may be, for example, silver nanowires (AgNWs).

[0081] Alternatively, the electrode layers 210 and 220 may be formed as a two-layer structure using a combination of the above materials, for example, a two-layer structure including a metal layer and a transparent conductive oxide layer to reduce the reflectance and increase the transmittance of incident light.

[0082] The electrode layers 210 and 220 may be formed by a method commonly used in the art, for example, coating processes such as spin coating, roller coating, bar coating, dip coating, gravure coating, curtain coating, die coating, spray coating, doctor coating, and kneader coating; printing (coating) processes such as screen printing, spray printing, inkjet printing, relief printing, intaglio printing, and planographic printing; and deposition processes such as CVD (chemical vapor deposition), PVD (physical vapor deposition), and PECVD (plasma enhanced chemical vapor deposition). As described above, the electrode layers 210 and 220 may be formed by directly performing the process on one surface of the polarizers 110 and 120.

[0083] In one embodiment, the electrode layer may include a plurality of unit electrodes, for example, the first electrode layer 210 may include a plurality of first unit electrodes 211, 212, 213, 214 arranged in a first direction (e.g., the x-axis direction), and the second electrode layer 220 may include a plurality of second unit electrodes 221, 222, 223, 224 arranged in a second direction (e.g., the y-axis direction).

[0084] The first unit electrodes 211, 212, 213, and 214 of the first electrode layer 210 and the second unit electrodes 221, 222, 223, and 224 of the second electrode layer 220 are perpendicular to each other to form unit cells, which are overlapping regions. The unit cells individually adjust the amount of light transmitted by applying a voltage from a driving circuit, and can selectively realize light-transmitting and light-blocking regions. Various embodiments of the present invention, based on specific driving methods of the unit cells, will be described in detail later.

[0085] The first unit electrodes 211, 212, 213, and 214 and the second unit electrodes 221, 222, 223, and 224 may be formed by etching the first electrode layer 210 and the second electrode layer 220, respectively, using a laser.

[0086] In this case, the first unit electrodes 211, 212, 213, 214 and the second unit electrodes 221, 222, 223, 224 may be formed in a stripe shape spaced apart from each other as shown in FIG. 1, but are not limited thereto and may be formed in various patterns such as a grid pattern.

[0087] When the unit electrodes are formed in a stripe pattern as shown in Figure 1, the interval between the unit electrodes is preferably 30 to 100 μm. If the interval between the unit electrodes is less than 30 μm, the laser irradiation intensity is high, which may damage the polarizer disposed underneath, and the electrode interval may be too narrow, which may cause current flow. If the interval between the unit electrodes is more than 100 μm, no electric field is formed in the gap, which may cause the gap to remain opaque regardless of whether a voltage is applied, which may cause a problem of being visible to the user.

[0088] The laser etching is preferably performed using a laser such as an excimer laser (fundamental wavelength of 193 to 308 nm), a YAG laser (fundamental wavelength of 1,064 nm), a fiber laser (fundamental wavelength of 1,060 nm), a CO2 laser (fundamental wavelength of 10,600 nm), and / or a semiconductor laser. In this case, the wavelength of the fundamental wave is preferably in the range of 500 to 11,000 nm in order to efficiently remove the electrode layer thin film in the laser light irradiated area and prevent damage to other components.

[0089] The laser etching conditions can be appropriately selected by the user depending on the spacing and etching depth of the unit electrodes to be formed. For example, laser etching may be performed under conditions of a laser power of 0.1 to 100 W, a pulse width of 1,000 ns or less, and a frequency of 10 to 1,000 kHz. Excessively low laser power tends to result in insufficient removal of the electrode layer thin film, but this tendency can be avoided to some extent by reducing the laser scanning speed or increasing the number of scans. Excessively high laser power may cause the removed portion of the electrode layer thin film to be significantly larger than the laser beam diameter due to heat diffusion from the irradiated area, resulting in poor pattern linearity of the unit electrodes, excessively narrow line width, or breakage. In this regard, it is preferable to appropriately adjust the laser power to 0.5 to 20 W, the frequency to 10 to 800 kHz, and the pulse width to 800 ns or less. More preferably, the laser power may be 0.5 to 12 W, the frequency to 10 to 600 kHz, and the pulse width to 600 ns or less.

[0090] Meanwhile, in FIG. 1, the first electrode layer 210 and the second electrode layer 220 are shown to include four first unit electrodes 211, 212, 213, 214 and four second unit electrodes 221, 222, 223, 224, respectively, but this is not necessarily limited to this and may be embodied by dividing them into various numbers of unit electrodes according to the needs of the user.

[0091] The liquid crystal layer 300 can change the driving mode of the optical stack by adjusting the transmittance of light incident in one or more directions by an electric field.

[0092] In one embodiment, the liquid crystal layer 300 may refer to an area driven by the liquid crystal compound 310, for example, an area defined by an alignment film (not shown) and a sealant (not shown) described below, and may further include a spacer (not shown) according to the user's needs.

[0093] The liquid crystal compound 310 is not particularly limited as long as it is driven by an electric field and can control light transmittance, and any conventional or later developed liquid crystal compound may be used. For example, the above-described reactive liquid crystal compound of the coating-type polarizer may be similarly applied.

[0094] The liquid crystal behavior mode of the liquid crystal layer 300 is not particularly limited, and for example, as shown in FIG. 1, it may be driven in a TN (Twisted Nematic) mode, or alternatively, it may be driven in an STN (Super Twisted Nematic) mode, a VA (Vertical Alignment) mode, an ECB (Electrically Controlled Birefringence) mode, etc.

[0095] The spacers may include ball spacers and / or column spacers, and are preferably ball spacers in terms of ease of manufacturing process.

[0096] The spacer may be one or more, and preferably has a height of 1 μm to 10 μm. Furthermore, when viewed from the planar direction, the area of ​​the liquid crystal layer occupied by the spacer is preferably 0.01 to 10% of the area of ​​the liquid crystal layer, from the viewpoints of improving user visibility and transmittance in the light-transmitting mode.

[0097] The alignment film is not particularly limited as long as it can impart alignment to the liquid crystal compound, and in one embodiment, it may be manufactured by a rubbing process. In this case, the alignment film is formed by manufacturing a layer of various materials applicable to alignment films, such as polyimide, and then rubbing the surface of the material layer using a rubbing roll to form fine line-shaped concave and convex shapes.

[0098] In another embodiment, the alignment film may include a photo-alignable or photo-curable polymer, and may be fabricated by applying and curing an alignment film coating composition including a photo-alignable or photo-curable polymer, a photopolymerization initiator, and a solvent.

[0099] The photo-alignable or photo-curable polymer is not particularly limited, and may be a cinnamate-based polymer, a polyimide-based polymer, or the like, such as poly(vinyl cinnamate) (PVCi), poly(siloxane cinnamate) (PSCN), poly(ω(4-chalconyloxy)alkoxyphenylmaleimide), 6-FDA-HAB-Cl, or any other conventional or later-developed polymer capable of exhibiting alignment.

[0100] In another embodiment, the alignment film may be manufactured by shaping a fine line-shaped uneven shape manufactured by a rubbing process, instead of the alignment film or photo-alignment alignment film manufactured by the rubbing process described above.

[0101] The sealant may be formed along the inactive region of the liquid crystal layer, i.e., the outer peripheral surface, to bond the first and second polarizers, and may be provided together with a spacer to secure a space for the liquid crystal layer between the first and second polarizers.

[0102] The sealant may include a curable resin as a base resin. The base resin may be a UV-curable resin or a thermosetting resin known in the art for use in sealants. The UV-curable resin may be a polymer of a UV-curable monomer. The thermosetting resin may be a polymer of a thermosetting monomer.

[0103] The base resin of the sealant may be, for example, an acrylate-based resin, an epoxy-based resin, a urethane-based resin, a phenol-based resin, or a mixture of these resins. In one embodiment, the base resin may be an acrylate-based resin, and the acrylate-based resin may be a polymer of an acrylic monomer. The acrylic monomer may be, for example, a multifunctional acrylate. In another embodiment, the sealant may further include a monomer component in the base resin. The monomer component may be, for example, a monofunctional acrylate. In this specification, a monofunctional acrylate may refer to a compound having one acrylic group, and a multifunctional acrylate may refer to a compound having two or more acrylic groups. The curable resin may be cured by ultraviolet irradiation and / or heating. The ultraviolet irradiation conditions or heating conditions may be appropriately set within a range that does not impair the objectives of the present application. The sealant may further include an initiator, for example, a photoinitiator or a thermal initiator, if necessary.

[0104] The sealant may be formed by a method commonly used in the art, for example, by drawing the sealant onto the outer periphery (i.e., non-active area) of the liquid crystal layer using a dispenser equipped with a nozzle.

[0105] Hereinafter, a driving mode of the variable transmittance optical laminate of the present invention by individually driving the unit cells will be described.

[0106] Meanwhile, before describing the driving mode by individually driving the unit cells, the light-transmitting mode and the light-blocking mode of the optical stack according to the exemplary embodiment of the present invention will be described first.

[0107] In the optical stack according to the exemplary embodiment, it is assumed that the absorption axes of the first polarizer and the second polarizer are perpendicular to each other, and the liquid crystal layer is driven in a twisted nematic (TN) mode.

[0108] Here, it is assumed that the absorption axis of the first polarizer is designed to be parallel to the y-axis in the planar direction, the absorption axis of the second polarizer is designed to be parallel to the x-axis in the planar direction, and the absorption axes of the first polarizer and the second polarizer are arranged to be perpendicular to each other.

[0109] It is also assumed that the long axis of the liquid crystal compound arranged adjacent to the first polarizer in the liquid crystal layer is arranged parallel to the x-axis in the planar direction and is designed to be perpendicular to the absorption axis of the first polarizer, and the long axis of the liquid crystal compound arranged adjacent to the second polarizer is arranged parallel to the y-axis in the planar direction and is designed to be perpendicular to the absorption axis of the second polarizer.

[0110] To explain the light transmission mode of the optical laminate, external light incident from the back side of the optical laminate (meaning the outside of the second polarizer, and hereinafter used in the same sense) is linearly polarized by the second polarizer of the optical laminate so that it is parallel to the y-axis in the planar direction.

[0111] At this time, when no driving voltage is applied to the liquid crystal layer, the liquid crystal molecules disposed within the liquid crystal layer maintain their initial alignment state.

[0112] Therefore, the external light linearly polarized in the y-axis direction passes through the liquid crystal compound disposed inside the liquid crystal layer and becomes linearly polarized light parallel to the x-axis in the same plane direction as the transmission axis of the first polarizer, and the linearly polarized external light passes through the first polarizer.

[0113] As a result, external light is output through the first polarizer, realizing a light transmission mode in which an object or image located on the rear side of the optical stack can be seen.

[0114] In addition, in terms of the light blocking mode of the optical laminate, external light incident from the rear side of the optical laminate is linearly polarized by the second polarizer of the optical laminate so as to be parallel to the y-axis in the planar direction.

[0115] At this time, when a driving voltage is applied to the liquid crystal layer, the liquid crystal compound disposed in the liquid crystal layer changes its alignment in the thickness direction of the liquid crystal layer, that is, parallel to the z-axis direction.

[0116] Therefore, the external light linearly polarized in the y-axis direction passes through the liquid crystal compound arranged inside the liquid crystal layer as it is and becomes linearly polarized light parallel to the y-axis in the planar direction, similar to the absorption axis of the first polarizer, and the linearly polarized external light is absorbed by the first polarizer and cannot pass through.

[0117] As a result, external light is ultimately blocked from being output by the first polarizer, thereby realizing a light-blocking mode in which objects or images located behind the optical stack cannot be seen.

[0118] Figures 2 to 5 are diagrams for explaining various driving modes of the variable transmittance optical laminate of the present invention, taking as an example the optical laminate according to the exemplary embodiment having a unit electrode matrix of (10x10). Specifically, Figure 2 shows the full light transmission mode, Figure 3 shows the mosaic mode, and Figures 4 and 5 show the gradation mode.

[0119] Referring to Figures 2 to 5, an optical stack according to an exemplary embodiment of the present invention may include a first electrode layer having first unit electrodes in rows 1 to 10; a second electrode layer having second unit electrodes in columns 1 to 10; and a driving circuit section 1000 for applying a driving voltage to each of the plurality of unit electrodes.

[0120] The first and second unit electrodes may be arranged perpendicular to each other to form a unit cell P, which is an overlapping region, and the unit cell P may be driven individually by adjusting the driving voltages of the first and second unit electrodes.

[0121] According to an exemplary driving method of the present invention, driving voltages may not be applied to all of the first unit electrodes and the second unit electrodes by the driving circuit unit 1000. In this case, all unit cells P of the optical stack are driven to the light-transmitting mode by the above-described mechanism, and a full light-transmitting mode is realized as shown in FIG. 2, thereby allowing objects or images located on the rear side of the optical stack to be clearly recognized.

[0122] According to another exemplary driving method of the present invention, the driving circuit unit 1000 may apply a maximum voltage to the unit electrodes in the first to third rows of the first unit electrodes and connect a voltage to the unit electrodes in the first to fourth columns of the second unit electrodes. In this case, the maximum driving voltage is applied to the unit cells P in the region where the unit electrodes in the first to third rows and the first to fourth columns overlap, and the unit cells P in the region are driven in the light-blocking mode according to the above-described mechanism, and no driving voltage is applied to the remaining unit cells P, and the unit cells P in the region are driven in the light-transmitting mode according to the above-described mechanism. Thus, as shown in FIG. 3, the unit cells in the region driven in the light-blocking mode may be embodied as the light-blocking region B, and the remaining unit cells driven in the light-transmitting mode may be embodied as the light-transmitting region T.

[0123] According to another exemplary driving method of the present invention, the driving circuit unit 1000 may apply a maximum voltage to the unit electrodes in the first and second rows of the first unit electrodes, apply a voltage lower than the maximum voltage to the unit electrodes in the third to seventh rows, and connect a voltage to the unit electrodes in the first to tenth columns of the second unit electrodes. In this case, the maximum driving voltage is applied to the unit cells P in an area where the unit electrodes in the first and second rows and the first to tenth columns overlap, and the unit cells P in that area are driven to the light-blocking mode according to the above-mentioned mechanism, and a driving voltage lower than the maximum driving voltage is applied to the unit cells P in an area where the unit electrodes in the third to seventh rows and the first to tenth columns overlap, and the unit cells P in that area are driven to the gray mode, which has a light-blocking rate lower than that of the light-blocking mode, according to the above-mentioned mechanism, and no driving voltage is applied to the remaining unit cells P, and the unit cells P in that area are driven to the light-transmitting mode according to the above-mentioned mechanism. As a result, as shown in FIG. 4, the unit cells in the region driven in the light-blocking mode may be embodied as a light-blocking region B, the unit cells in the region driven in the gray mode may be embodied as a gray region G, and the remaining unit cells in the light-transmitting mode may be embodied as a light-transmitting region T.

[0124] According to another exemplary driving method of the present invention, the driving circuit unit 1000 may apply a maximum voltage to the unit electrodes in the first to third columns and the ninth to tenth columns of the second unit electrodes, apply a voltage lower than the maximum voltage to the unit electrodes in the fourth to eighth columns, and connect a voltage to the unit electrodes in the first to tenth rows of the first unit electrodes. In this case, the maximum driving voltage is applied to the unit cells P in the region where the unit electrodes in the first to third columns, the ninth to tenth columns, and the first to tenth rows overlap, and the unit cells P in the region are driven to the light-blocking mode according to the above-described mechanism, and a driving voltage lower than the maximum driving voltage is applied to the unit cells P in the region where the unit electrodes in the fourth to eighth columns and the first to tenth rows overlap, and the unit cells P in the region are driven to the gray mode, which has a light-blocking rate lower than that of the light-blocking mode, according to the above-described mechanism. Therefore, as shown in FIG. 5, the unit cells in the region driven in the light blocking mode may be embodied as a light blocking region B, and the unit cells in the region driven in the gray mode may be embodied as a gray region G.

[0125] Meanwhile, as mentioned above, the exemplary driving methods of the present invention are merely for the purpose of explaining the embodiments of the present invention, and therefore the present invention is not necessarily limited to the driving methods described above.

[0126] In one embodiment, the driving voltage for driving the unit cell may be appropriately set according to the needs of the user. However, in the case of the present invention, since a substrate for forming an electrode layer is not included, the thickness of the laminate is thin, and the unit cell is driven by a liquid crystal layer including polarizers and a liquid crystal compound disposed on both sides of the laminate, it can be driven at a lower driving voltage than a method driven by a polymer dispersed liquid crystal (PDLC) or electrophoretic particle. For example, it has the characteristic that the maximum transmittance and the minimum transmittance per unit cell can be realized at a driving voltage of 10 V or less.

[0127] In one embodiment, the maximum transmittance is preferably 35% to 45% from the front direction, and the minimum transmittance is preferably 0% to 3% from the front direction. When the maximum transmittance and minimum transmittance satisfy the above ranges, objects or images located behind the laminate can be clearly recognized in the light-transmitting mode, and external light can be effectively blocked in the light-blocking mode, which is advantageous in that external light transmittance can be effectively controlled when switching modes.

[0128] The variable transmittance optical laminate of the present invention may further include other components within the scope that does not impair the object of the present invention, for example, it may further include an adhesive layer, an ultraviolet absorbing layer, and / or a hard coating layer.

[0129] The adhesive layer may be formed using an adhesive or pressure-sensitive adhesive, and may be formed on one or both sides of the optical laminate. It preferably has an appropriate adhesive strength so as to prevent peeling, bubbles, etc. from occurring when the optical laminate is handled, as well as transparency and thermal stability.

[0130] The adhesive may be a conventional or later developed adhesive, for example, a light-curable adhesive.

[0131] The photocurable adhesive exhibits strong adhesive strength by crosslinking and curing when exposed to active energy rays such as ultraviolet (UV) and electron beam (EB), and may be composed of a reactive oligomer, a reactive monomer, a photopolymerization initiator, etc.

[0132] The reactive oligomer is an important component that determines the properties of the adhesive and forms a hardened coating by forming a polymer bond through a photopolymerization reaction. Usable reactive oligomers include polyester resins, polyether resins, polyurethane resins, epoxy resins, polyacrylic resins, and silicone resins.

[0133] The reactive monomer functions as a crosslinking agent and a diluent for the reactive oligomer, and influences adhesive properties. Usable reactive monomers include monofunctional monomers, polyfunctional monomers, epoxy-based monomers, vinyl ethers, cyclic ethers, etc.

[0134] The photopolymerization initiator absorbs light energy to generate radicals or cations, thereby initiating photopolymerization, and may be selected to suit the photopolymerizable resin.

[0135] The pressure-sensitive adhesive may be a conventional or later-developed pressure-sensitive adhesive, and in one or more embodiments, may be an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a polyvinyl alcohol pressure-sensitive adhesive, a polyvinylpyrrolidone pressure-sensitive adhesive, a polyacrylamide pressure-sensitive adhesive, a cellulose pressure-sensitive adhesive, a vinyl alkyl ether pressure-sensitive adhesive, etc. The pressure-sensitive adhesive is not particularly limited as long as it has adhesive strength and viscoelasticity, but from the viewpoint of availability, etc., it may preferably be an acrylic pressure-sensitive adhesive, which may contain, for example, a (meth)acrylate copolymer, a crosslinking agent, and a solvent.

[0136] The crosslinking agent may be a conventional or later developed crosslinking agent, and may include, for example, a polyisocyanate compound, an epoxy resin, a melamine resin, a urea resin, a dialdehyde, a methylol polymer, or the like, and preferably includes a polyisocyanate compound.

[0137] The solvent may include conventional solvents used in the field of resin compositions, such as alcohol-based compounds such as methanol, ethanol, isopropanol, butanol, and propylene glycol methoxyalcohol; ketone-based compounds such as methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, and dipropyl ketone; acetate-based compounds such as methyl acetate, ethyl acetate, butyl acetate, and propylene glycol methoxyacetate; cellosolve-based compounds such as methyl cellosolve, ethyl cellosolve, and propyl cellosolve; and hydrocarbon-based compounds such as hexane, heptane, benzene, toluene, and xylene. These may be used alone or in combination of two or more.

[0138] The thickness of the adhesive layer may be appropriately determined depending on the type of resin acting as the adhesive, adhesive strength, the environment in which the adhesive is used, etc. In one embodiment, the adhesive layer may have a thickness of 0.01 to 50 μm, preferably 0.05 to 20 μm, more preferably 0.1 to 10 μm, in order to ensure sufficient adhesive strength and minimize the thickness of the optical laminate.

[0139] In one embodiment, the adhesive layer may be formed on one or both surfaces of the polarizing plate by lamination.

[0140] The ultraviolet absorbing layer is not particularly limited as long as it is used to prevent deterioration of the optical laminate due to ultraviolet rays, and examples thereof include salicylic acid-based ultraviolet absorbers (phenyl salicylate, p-tert-butyl salicylate, etc.), benzophenone-based ultraviolet absorbers (2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, etc.), benzotriazole-based ultraviolet absorbers (2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t 2-(2'-hydroxy-3'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-(3'',4'',5'',6''-tetrahydrophthalimidomethyl)-5'-methylphenyl)benzotriazole, 2,2-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazo 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-(2-octyloxycarbonylethyl)-phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-(1-methyl-1-phenylethyl)-5'-(1,1,3,3-tetramethylbutyl)-phenyl)benzotriazole, 2-(2H-benzotriazol-2-yl)-6-(linear and side chain dodecyl)-4-methylphenol, a mixture of octyl-3-[3-tert-butyl-4-hydroxy-5-(chloro-2H-benzotriazol-2-yl)phenyl]propionate and 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate, etc.), cyanoacrylate ultraviolet absorbers (2'-ethylhexyl-2-cyano-3,3-diphenylacrylate, ethyl-2-cyano-3-(3',4'-methylenedioxyphenyl)acrylate, triazine-based UV absorbers, etc. may also be used, and benzotriazole-based UV absorbers or triazine-based UV absorbers, which have high transparency and are excellent in preventing deterioration of polarizing plates and transmittance-variable layers, are preferred, and benzotriazole-based UV absorbers with a more suitable spectral absorption spectrum are particularly preferred. The benzotriazole-based UV absorbers may be bis(bis)-modified, such as 6,6'-methylenebis(2-(2H-benzo[d][1,2,3]triazol-2-yl)-4-(2,4,4-trimethylpentan-2-yl)phenol) or 6,6'-methylenebis(2-(2H-benzo[d][1,2,3]triazol-2-yl)-4-(2-hydroxyethyl)phenol).

[0141] The hard coating layer is not particularly limited as long as it protects components such as a polarizing plate and a transmittance variable layer from external physical and chemical impacts, and any conventional or later developed hard coating layer may be used.

[0142] In one embodiment, the hard coating layer may be formed by applying a composition for forming a hard coating layer to another member and curing the composition with light or heat. The composition for forming a hard coating layer is not particularly limited and may include, for example, a photocurable compound and a photoinitiator.

[0143] The epoxy compound, acrylate-based compound, and photoinitiator may be any compound commonly used in the art, without any limitation. For example, the epoxy compound may be a monomer or oligomer having at least one epoxy group in the molecule, the acrylate-based compound may be a monomer or oligomer containing a (meth)acrylate group, and the photoinitiator may be an oxime ester-based compound, etc.

[0144] The present invention includes the variable transmittance optical laminate, as well as a smart window including the same. The present invention also includes a means of transportation including the smart window, for example, a vehicle in which the smart window is applied to at least one of a front window, a rear window, a side window, a sunroof window, and an interior partition, a wearable device including the smart window, and a building fixture.

[0145] For example, a vehicle including the smart window of the present invention may include a smart window formed by bonding glass to both sides of the optical laminate. The smart window may be manufactured by, for example, placing an adhesive film and glass on both sides of the optical laminate, and then heating the resulting structure at 90°C and a vacuum of approximately 1 bar for 10 to 20 minutes using a press. Alternatively, the smart window may be manufactured by coating a resin on one side of the glass, vacuum bonding the glass to both sides of the optical laminate, and then UV-curing the resulting structure. The adhesive film may include an EVA (Ethylene Vinyl Acetate copolymer) film, a PVB (Poly Vinyl Butyral) film, or the like, and the resin may include an optically clear resin (OCR), or the like.

[0146] The optically transparent resin OCR may contain a urethane-based resin, an acrylic-based resin, a silicone-based resin, or the like, and may preferably contain a silicone-based resin from the viewpoints of excellent heat resistance, ease of availability, and the like.

[0147] The optical laminate may also have building fixtures (glass for fixtures) bonded to one or both sides thereof, or may have glass for fixtures bonded to one side of the optical laminate by lamination to produce a smart window product for fixtures, or may have glass for fixtures coated with UV adhesive on both sides of the optical laminate, bonded, and then UV-cured to produce a smart window product for fixtures. [Example]

[0148] Hereinafter, specific exemplary embodiments of the optical laminate according to the present invention will be described. However, the present invention is not limited to the embodiments disclosed below and can be embodied in various different forms. However, the present embodiments are provided to complete the disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims.

[0149] Manufacturing Example 1: Manufacturing of polarizing plates (1) Swelling treatment process A 60 μm thick polyvinyl alcohol film (raw film) (manufactured by Kuraray Co., Ltd., product name "Kuraray Poval Film VF-PE#6000", average polymerization degree 2400, saponification degree 99.9 mol%) was continuously unwound from a raw roll and transported, and immersed in a swelling bath containing pure water at 20°C for 30 seconds. In this swelling treatment process, inter-roll stretching (longitudinal uniaxial stretching) was performed with a difference in peripheral speed between the nip rolls. The stretching ratio based on the raw film was 2.5 times.

[0150] (2) Dyeing process Next, the film passed through the nip rolls was immersed in a dye bath containing pure water / potassium iodide / iodine / boric acid (mass ratio) of 100 / 2 / 0.01 / 0.3 at 30°C for 120 seconds. In this dyeing treatment, roll-to-roll stretching (longitudinal uniaxial stretching) was also performed with a difference in peripheral speed between the nip rolls. The stretching ratio based on the film after the swelling treatment step was 1.1 times.

[0151] (3) Crosslinking process Next, the film that passed through the nip rolls was immersed for 70 seconds in a first crosslinking bath at 56°C containing pure water / potassium iodide / boric acid (mass ratio) of 100 / 12 / 4. Roll-to-roll stretching (longitudinal uniaxial stretching) was performed with a difference in peripheral speed between the nip rolls and a nip roll prepared between the first and second crosslinking baths. The stretching ratio was 1.9 times, based on the film after the dyeing treatment process.

[0152] (4) Complementary color processing process Next, the film after the crosslinking treatment was immersed for 10 seconds in a second crosslinking bath at 40° C. containing potassium iodide / boric acid / pure water (mass ratio) of 9 / 2.9 / 100.

[0153] (5) Cleaning process Next, the film after the second crosslinking treatment was immersed in a cleaning bath containing pure water at 14°C for 5 seconds, and the shower volume was 5 m 3 Washing was performed at 14°C / h and shower temperature.

[0154] (6) Drying process The washed film was then passed through a drying path and heated and dried at 80°C for 190 seconds to produce a polarizer film. The moisture content after drying was 13.6%, and the thickness of the resulting polarizer film was approximately 21µm.

[0155] (7) Bonding process Next, a water-based adhesive containing 5 parts by weight of polyvinyl alcohol per 100 parts by weight of water was prepared as the adhesive. Then, protective films were laminated on both sides of the polarizer film using the prepared UV adhesive. The resulting laminate was exposed to UV light to harden the adhesive, producing a polarizing plate. The thickness of the adhesive layer in the resulting polarizing plate was approximately 2 μm.

[0156] Preparation Example 2: Preparation of hard coating composition A hard coating composition was prepared by mixing 16.2 g of a dendrimer compound (Miwan Specialty Chemical, SP-1106), 14.4 g of inorganic nanoparticles (50 wt% silica particles with an average particle size of 10 to 20 nm, solvent: methyl ethyl ketone (MEK)), 1.8 g of a multifunctional (meth)acrylate containing an ethylene glycol group, 0.7 g of a photoinitiator (1-hydroxycyclohexylphenyl ketone), and 2.9 g of methyl ethyl ketone.

[0157] Manufacturing Example 3: Production of hard coating layer The hard coating composition prepared in Preparation Example 2 was bar-coated on one surface of a polarizing plate using a #10 Mayer bar, dried at 80°C for 5 minutes, and then irradiated with 500 mJ / cm 2 of a high-pressure mercury lamp. 2 The coating was cured with a light dose of 1000 to produce a hard coating layer with a thickness of about 7 μm.

[0158] Manufacturing Example 4: Manufacturing of electrode layer A polarizer with the hard coating layer of Preparation Example 3 was placed in the substrate, and a sputtering gun was operated by applying 450 W DC power to the hard coating layer. Plasma was then induced on an ITO (10 wt% Sn-doped In2O3) target to form an ITO electrode layer (90 nm). An ion gun was operated at 50 W DC power to treat the electrode layer with ions. Argon gas and oxygen gas were supplied at 30 sccm and 1 sccm, respectively, at room temperature under a pressure of 3 mTorr. The ITO thickness was measured using a FT-SEM.

[0159] Manufacturing Example 5: Fabrication of alignment film An alignment liquid was coated on the ITO electrode layer of each of the upper and lower polarizers prepared in Preparation Example 4 and dried (80°C / 2 minutes). Then, UV light was irradiated onto the dried alignment liquid to prepare an alignment film.

[0160] Manufacturing Example 6: Formation of unit electrode (production of electrode layer separation groove) A Gaussian laser beam was continuously irradiated onto the alignment layers of the upper and lower polarizers fabricated in Preparation Example 5 to etch the alignment layers and the ITO electrode layers, and then etching to a depth of about 1 μm on the hard coating layer to form a plurality of electrically isolated unit electrodes in each electrode layer. Five separation grooves were formed in each electrode layer, resulting in a (6 × 6) matrix of unit electrodes.

[0161] Manufacturing Example 7: Ball spacer scattering manufacturing The ball spacer mixed solvent was prepared by mixing 0.03 g of ball spacers (SEKISUI SP series) with 100 ml of isopropyl alcohol (IPA).The lower polarizer prepared in Preparation Example 6 was then placed in a spacer sprayer (SDSS-KHU02, Shindo Eng Lab Ltd) and the mixed solvent was sprayed at 110°C, followed by drying for 20 minutes to form ball spacers on the alignment layer.

[0162] Production Example 8: Production of optical laminate Using a sealant dispenser (SHOTmini 200Ωx, MUSASHI Co., Ltd.), a sealant (Photolec A, 10,000 mPa·s, SEKISUI Co., Ltd.) was applied to the outer periphery of the ITO electrode layer of the lower polarizer fabricated in Preparation Example 7 using a sharp needle (SPN-0.25-12.7L) at a discharge pressure of 200 mPa according to the product size drawing, and liquid crystal was injected onto the alignment film using the ODF (One Drop Filling) process. Then, the upper polarizer fabricated in Preparation Example 6 was placed parallel to the lower polarizer so that the polarization axis of the upper polarizer was at 0° or 90° to the polarization axis of the lower polarizer, and the unit electrodes formed on the upper polarizer and the lower polarizer were perpendicular to each other, and a liquid crystal was injected at 3 kg / cm. 2 After pressure bonding, UV curing (500 mJ / cm) was performed along the sealant line. 2 ) was carried out to produce an optical laminate for smart windows.

[0163] Manufacturing Example 9: Manufacturing of connection pads A conductive copper tape (TERAOKA, No. 8323) was attached to one end of each unit electrode formed on the upper and lower ITO electrode layers of the optical laminate manufactured in Preparation Example 8 to form a connection pad.

[0164] Experimental example: Measurement of transmittance depending on voltage strength for each unit cell The transmittance of each unit cell of the optical laminates for smart windows manufactured in Preparation Examples 1 to 9 was measured according to the driving voltage, and the results are shown in Table 1 and FIG.

[0165] [Table 1]

[0166] Referring to Table 1 and FIG. 6, the optical laminate according to the exemplary embodiment of the present invention has a transmittance of 40.2% in the light-transmitting mode (applied voltage 0V), allowing objects or images located behind the laminate to be clearly recognized, and a transmittance of 0.1% in the light-blocking mode (applied voltage 10V or more), allowing external light to be effectively blocked.

[0167] In addition, the lower limit of transmittance in the light-blocking mode is reached at an applied voltage of 10V, which indicates that the layered structure smoothly switches between the light-blocking mode and the light-transmitting mode even at a driving voltage of 10V, which is relatively low compared to conventional optical layered structures.

[0168] Furthermore, it is possible to appropriately adjust the transmittance at a driving voltage exceeding 0V and less than 10V, and it is understood that the transmittance in the gray mode can be appropriately set according to the needs of the user. [Industrial Applicability]

[0169] The variable transmittance optical stack according to the present invention includes a plurality of divided driving regions, thereby enabling various modes to be realized compared to conventional optical stacks. Specifically, when a voltage is applied to the electrode layer, the unit cells can be driven individually, thereby selectively driving only a desired unit region.

Claims

1. a first polarizer; a first electrode layer formed on one surface of the first polarizing plate; a second polarizing plate facing the first polarizing plate; a second electrode layer formed on one surface of the second polarizer and facing the first electrode layer; and a liquid crystal layer provided between the first electrode layer and the second electrode layer; At least one of the first electrode layer and the second electrode layer is formed in direct contact with one of the first polarizer and the second polarizer, the first electrode layer includes a plurality of first unit electrodes arranged in a first direction; The second electrode layer includes a plurality of second unit electrodes arranged in a second direction.

2. The variable transmittance optical stack according to claim 1 , wherein the unit electrodes are formed in stripes spaced apart from each other.

3. The variable transmittance optical laminate according to claim 1 , wherein the first unit electrodes and the second unit electrodes are arranged so as to be perpendicular to each other.

4. The variable transmittance optical laminate according to claim 1 , wherein the interval between the unit electrodes is 30 to 100 μm.

5. The variable transmittance optical laminate of claim 1 , wherein the variable transmittance optical laminate exhibits maximum and minimum transmittances at a driving voltage of 10 V or less.

6. The variable transmittance optical stack of claim 5 , wherein the maximum transmittance is from 35% to 45%.

7. 6. The variable transmittance optical stack of claim 5, wherein the minimum transmittance is between 0% and 3%.

8. The variable transmittance optical laminate according to claim 1 , further comprising a driving circuit unit for applying individual driving voltages to the unit electrodes.

9. 2. The variable transmittance optical laminate of claim 1, wherein at least one of the first electrode layer and the second electrode layer comprises at least one selected from the group consisting of transparent conductive oxides, metals, carbon-based materials, conductive polymers, conductive inks, and nanowires.

10. The variable transmittance optical laminate of claim 1 , wherein at least one of the first polarizer and the second polarizer has a thickness of 30 to 200 μm.

11. The variable transmittance optical laminate according to claim 1, wherein the liquid crystal layer comprises one or more spacers selected from the group consisting of ball spacers and column spacers.

12. 12. The variable transmittance optical stack of claim 11, wherein the spacers have a height of 1 to 10 μm.

13. The variable transmittance optical stack according to claim 11, wherein the area occupied by the spacer in the liquid crystal layer is 0.01% to 10% of the area of ​​the liquid crystal layer.

14. The variable transmittance optical laminate according to claim 1 , further comprising at least one layer selected from the group consisting of an overcoat layer, an adhesive layer, an ultraviolet absorbing layer, and a hard coating layer.

15. A smart window comprising the variable transmittance optical stack of any one of claims 1 to 14.

16. A means of transportation comprising the smart window of claim 15.

17. 16. A car in which the smart window according to claim 15 is applied to at least one of a front window, a rear window, a side window, a sunroof window, and an interior partition.

18. A wearable device comprising the smart window of claim 15.

19. Architectural fittings comprising the smart window of claim 15.

Images