KR102717155B1 - Optical laminate, and manufacturing method for the same, and smart window including the same, and automobile or windows for buiding using the same - Google Patents

Abstract

The present invention relates to a transmittance variable optical laminate comprising: a first polarizing plate; a first transparent conductive layer formed on one surface of the first polarizing plate; a second polarizing plate facing the first polarizing plate; a second transparent conductive layer formed on one surface of the second polarizing plate and facing the first transparent conductive layer; and a liquid crystal layer provided between the first transparent conductive layer and the second transparent conductive layer, wherein at least one transparent conductive layer of the first transparent conductive layer and the second transparent conductive layer is formed in direct contact with one of the polarizing plates of the first polarizing plate and the second polarizing plate, and the transmittance variable optical laminate has a surface roughness value of 15 to 60 ㎛ on at least one side; a method for manufacturing the same; a smart window comprising the same; and a window for an automobile or a building to which the same is applied.

Description

Optical laminate, and manufacturing method thereof, and smart window including the same, and window for automobile or building using the same {OPTICAL LAMINATE, AND MANUFACTURING METHOD FOR THE SAME, AND SMART WINDOW INCLUDING THE SAME, AND AUTOMOBILE OR WINDOWS FOR BUIDING USING THE SAME}

The present invention relates to a transmittance variable optical laminate and a method for manufacturing the same, a smart window including the same, and a window for an automobile or building to which the same is applied.

In general, external light blocking coatings are often applied to the windows of vehicles and other means of transportation. However, the windows of conventional means of transportation have fixed transmittance, and the external light blocking coating also has fixed transmittance. Therefore, the windows of such conventional means of transportation have fixed overall transmittance, which may cause accidents. For example, if the overall transmittance is set low, there is no problem during the day when there is sufficient surrounding light, but at night when there is not enough surrounding light, there is a problem that drivers and others may have difficulty properly checking the surroundings of the means of transportation. Alternatively, if the overall transmittance is set high, there is a problem that drivers and others may experience glare during the day when there is sufficient surrounding light. Therefore, a transmittance-variable optical laminate capable of changing the transmittance of light when voltage is applied has been developed.

The above-mentioned variable transmittance optical laminate is driven by varying the transmittance by driving the liquid crystal according to the application of voltage. The variable transmittance optical laminate developed to date is manufactured by forming a conductive layer for driving the liquid crystal on a separate substrate and then combining this with other elements such as a polarizing plate.

For example, Japanese Patent Publication No. 2018-010035 also discloses a transmittance variable optical laminate including a transparent electrode layer formed on a polycarbonate (PC) substrate or the like having a predetermined thickness.

However, if a separate substrate is included to form a challenging layer in this way, the manufacturing process becomes complicated, which increases manufacturing costs, increases the thickness of the laminate, and causes a change in transmittance due to a phase difference.

In addition, there is a problem that air bubbles are generated at the interface between the sealant used to bond the optical laminate and other materials such as glass during the production of a smart window, and the side surface of the optical laminate contacts it, or the adhesion is reduced.

Accordingly, there is a need for the development of a transmittance variable optical laminate that can simplify the manufacturing process of the optical laminate, reduce the thickness, and have improved adhesion without generating bubbles at the contact interface between the optical laminate and other materials such as a sealant.

Japanese Publication Patent No. 2018-010035

The purpose of the present invention is to provide a transmittance variable optical laminate whose manufacturing process is simplified by not including a separate substrate for forming a conductive layer.

In addition, the present invention aims to provide a variable transmittance optical laminate having a significantly reduced thickness by not including a separate substrate for forming a conductive layer.

In addition, the present invention aims to provide a variable transmittance optical laminate having improved transmittance in a light-transmitting mode by not including a separate substrate for forming a conductive layer.

In addition, the present invention aims to suppress the occurrence of bubbles at a contact interface with other materials used in the production of a smart window by controlling the surface roughness value on at least one side of an optical laminate.

In addition, the present invention aims to improve adhesion at a contact interface with another material used in the production of a smart window by controlling the surface roughness value on at least one side of an optical laminate.

In addition, the present invention aims to provide a smart window including the above-described variable transmittance optical laminate and a window for an automobile or building to which the same is applied.

However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

The present invention relates to a transmittance variable optical laminate comprising: a first polarizing plate; a first transparent conductive layer formed on one surface of the first polarizing plate; a second polarizing plate facing the first polarizing plate; a second transparent conductive layer formed on one surface of the second polarizing plate and facing the first transparent conductive layer; and a liquid crystal layer provided between the first transparent conductive layer and the second transparent conductive layer, wherein at least one transparent conductive layer of the first transparent conductive layer and the second transparent conductive layer is formed in direct contact with one of the polarizing plates of the first polarizing plate and the second polarizing plate, and the transmittance variable optical laminate has a surface roughness value of 15 to 60 µm on at least one surface.

In the first aspect of the present invention, the surface roughness value may be an average value of the maximum height difference for each of a plurality of measurement areas on the one side.

In the second aspect of the present invention, the maximum height difference may be a value measured in the height direction as the distance between the highest peak and the lowest valley in a roughness curve within a measurement area.

In the third aspect of the present invention, the distance between points indicating the maximum height difference for each of the plurality of measurement areas may be 50 μm or more.

In the fourth aspect of the present invention, at least one of the first transparent conductive layer and the second transparent conductive layer may be formed in direct contact with one of the first polarizing plate and the second polarizing plate without including a separate substrate therebetween.

In the fifth aspect of the present invention, at least one of the first transparent conductive layer and the second transparent conductive layer may be formed in direct contact with one of the first and second polarizing plates, such that the transparent conductive layer includes an adhesive-friendly layer between the first and second polarizing plates.

In the sixth aspect of the present invention, at least one of the transparent conductive layers among the first transparent conductive layer and the second transparent conductive layer may include at least one selected from the group consisting of transparent conductive oxides, metals, carbon-based materials, conductive polymers, conductive inks, and nanowires.

In the seventh aspect of the present invention, at least one of the first polarizing plate and the second polarizing plate may include at least one functional layer selected from the group consisting of a protective layer, a phase difference control layer, and a refractive index control layer.

In the eighth 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.

In the ninth aspect of the present invention, the liquid crystal layer may include at least one selected from the group consisting of a ball spacer and a column spacer.

In the tenth aspect of the present invention, the ball spacer may have a diameter of 1 to 10 μm.

In the eleventh aspect of the present invention, the occupied area of the ball spacer within the liquid crystal layer may be 0.01% to 10% of the area of the liquid crystal layer.

In addition, the present invention relates to a method for manufacturing the above-mentioned variable transmittance optical laminate.

In addition, the present invention relates to a smart window including the above-described variable transmittance optical laminate.

In the twelfth aspect of the present invention, the smart window may include a sealant provided to form a contact interface with at least one side of the variable transmittance optical laminate.

In addition, the present invention relates to an automobile 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.

In addition, the present invention relates to a window for a building including the smart window.

According to the optical laminate with variable transmittance according to the present invention, the process of forming a conductive layer on a substrate and bonding it with another member for forming a conventional optical laminate can be omitted, so that the manufacturing process can be simplified compared to the conventional optical laminate.

In addition, according to the optical laminate with variable transmittance according to the present invention, since the conductive layer is formed directly on one surface of the polarizing plate, a separate substrate for forming the conductive layer is not included, so that the thickness can be significantly reduced compared to the conventional optical laminate.

In addition, according to the optical laminate with variable transmittance according to the present invention, since the conductive layer is formed directly on one surface of the polarizing plate, a separate substrate for forming the conductive layer is not included, so that the transmittance in the light transmission mode can be improved compared to the conventional optical laminate.

In addition, according to the optical laminate with variable transmittance according to the present invention, by controlling the surface roughness value on at least one side of the optical laminate, the generation of bubbles at the contact interface with other materials used in manufacturing a smart window can be further suppressed compared to conventional optical laminates.

In addition, according to the optical laminate with variable transmittance according to the present invention, by controlling the surface roughness value on at least one side of the optical laminate, the adhesion at the contact interface with other materials used in manufacturing a smart window can be further improved compared to the conventional optical laminate.

Figures 1 to 3 are diagrams for explaining a method for measuring a surface roughness value on one side of a variable transmittance optical laminate of the present invention.
FIG. 4 is a diagram showing a laminated structure of a variable transmittance optical laminate according to an embodiment of the present invention.
FIG. 5 is a diagram showing a laminated structure of a polarizing plate according to one or more embodiments of the present invention.
FIG. 6 is a diagram illustrating a smart window according to an embodiment of the present invention.

The optical laminate with variable transmittance of the present invention is characterized in that the thickness of the laminate is reduced and the transmittance in the light transmission mode is improved by directly forming a transparent conductive layer for driving a liquid crystal on one side of a polarizing plate without including a separate substrate for forming the conductive layer. In addition, the optical laminate is characterized in that by controlling the surface roughness value on at least one side of the optical laminate, the generation of bubbles at the contact interface with other materials, such as a sealant used in manufacturing a smart window, is suppressed and the adhesion is further improved.

More specifically, the present invention relates to a transmittance variable optical laminate comprising: a first polarizing plate; a first transparent conductive layer formed on one surface of the first polarizing plate; a second polarizing plate facing the first polarizing plate; a second transparent conductive layer formed on one surface of the second polarizing plate and facing the first transparent conductive layer; and a liquid crystal layer provided between the first transparent conductive layer and the second transparent conductive layer, wherein at least one transparent conductive layer of the first transparent conductive layer and the second transparent conductive layer is formed in direct contact with one of the polarizing plates of the first polarizing plate and the second polarizing plate, and wherein the transmittance variable optical laminate has a surface roughness value of 15 to 60 µm on at least one surface.

The optical laminate with variable transmittance of the present invention is particularly suitable for a technical field in which the transmittance of light can be changed according to the application of voltage, and can be used, for example, in smart windows.

A smart window is an optical structure that controls the amount of light or heat that passes through by changing the light transmittance according to the application of an electrical signal. In other words, a smart window is provided so that it can be changed to a transparent, opaque, or translucent state by voltage, and is also called variable transmittance glass, dimming glass, or smart glass.

Smart windows can be used as partitions for dividing the interior space of vehicles and buildings or for privacy, or as skylights placed in openings of buildings, and can also be used as highway signs, bulletin boards, scoreboards, clocks or advertising screens, and can be used to replace glass in transportation means such as windows or sunroofs of cars, buses, airplanes, ships or trains.

The optical laminate with variable transmittance of the present invention can also be utilized as a smart window in the various technical fields described above, but since the conductive layer is formed directly on the polarizing plate, it does not include a separate substrate for forming the conductive layer, so it is thin and has advantageous bending characteristics, and can be particularly suitably used as a smart window for vehicles or buildings. In one or more embodiments, the smart window to which the optical laminate with variable transmittance of the present invention is applied can be used for front windows, rear windows, side windows, and sunroof windows of vehicles, or windows for buildings, and in addition to the purpose of blocking external light, it can also be used for partitioning internal spaces of vehicles or buildings, such as interior partitions, or for protecting privacy.

Hereinafter, with reference to the drawings, embodiments of the present invention will be described in more detail. However, the following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the contents of the invention described above, serve to further understand the technical idea of the present invention, so the present invention should not be interpreted as being limited to matters described in such drawings.

The terms used herein are for the purpose of describing embodiments and are not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. For example, as used herein, “polarizing plate” may mean at least one polarizing plate among the first polarizing plate and the second polarizing plate, and “transparent conductive layer” may mean at least one transparent conductive layer among the first transparent conductive layer and the second transparent conductive layer.

As used herein, the terms “comprises” and/or “comprising” are used to mean that they do not exclude the presence or addition of one or more other components, steps, operations, and/or elements other than the components, steps, operations, and/or elements mentioned. Like reference numerals refer to like elements throughout the specification.

Spatially relative terms such as “below,” “bottom,” “lower,” “upper,” “top,” and the like can be used to easily describe the relationship between one element or component and other elements or components, as depicted in the drawings. The spatially relative terms should be understood to include different orientations of the elements during use or operation in addition to the orientations depicted in the drawings. For example, if an element depicted in the drawings is flipped, an element described as “below” or “lower” of another element can be placed “above” the other element. Thus, the exemplary term “below” can include both the above and below directions. The elements can also be oriented in other directions, and thus the spatially relative terms can be interpreted according to the orientation.

As used herein, “plane direction” can be interpreted as a direction orthogonal to the polarizing plate and/or transparent conductive layer, i.e., the direction viewed from the user’s viewing side.

FIGS. 1 to 3 are diagrams for explaining a method for measuring a surface roughness value on one side of a transmittance variable optical laminate of the present invention. Specifically, FIG. 1 is a diagram for showing one side of the transmittance variable optical laminate of the present invention, FIG. 2 is an enlarged diagram of the one side of FIG. 1, and FIG. 3 is a diagram for showing a method for measuring a maximum height difference within a measurement area.

Referring to FIG. 1, the above-described one side may mean a side wall portion (S) in the y-axis direction with respect to the plane direction of the optical laminate as illustrated in FIG. 1, but is not limited thereto, and may mean, for example, a front or rear side wall portion in the x-axis direction.

The surface roughness value on the above-mentioned one side may mean the surface roughness value of the side wall portion (S) of the optical laminate, but if the measured surface roughness value can be interpreted as representing the surface roughness value of the side wall portion (S) within a range that does not harm the purpose of the present invention, it may also be interpreted as meaning the surface roughness value measured in a portion of the side wall portion (S) of the optical laminate. For example, if the surface roughness calculated as the average value of the maximum height difference for each of the 8 points in total of the vertex areas (a total of 4 points) and the middle point areas of the vertices (a total of 4 points) of the 200 ㎛ x 200 ㎛ areas belonging to the side wall portion of the optical laminate can be interpreted as the surface roughness value of the side wall portion, this can be regarded as the surface roughness value on the one side.

Referring to FIG. 2, the surface roughness value of the present invention may be defined as an average value of the maximum height difference for each of a plurality of measurement areas (Am1, Am2) on the one side (S), and for example, an average value of the maximum height difference of the first measurement area (Am1) and the maximum height difference of the second measurement area (Am2) may be defined as an average value of the maximum height differences for each of the plurality of measurement areas on the one side (S). Meanwhile, the number of the measurement areas may be 2 as shown in FIG. 2, but is not limited thereto, and is not particularly limited as long as it can be interpreted as a surface roughness value on the one side according to the needs of the user, such as 3, 4, 5, 6, 7, or 8.

Referring to FIG. 3, the maximum height difference may be a value (Ry) measured in the height direction between the highest peak (P _H ) and the lowest valley (P _L ) in a surface roughness curve of one measurement area, for example, the first measurement area (Am1).

The above-described plurality of measurement areas are not particularly limited as long as the measured values can represent the surface roughness value on one side (S), but it is preferable that the distance between points representing the maximum height difference for each of the plurality of measurement areas be 50 ㎛ or more. For example, as illustrated in Fig. 2, the minimum distance (d) between the first measurement area (Am1) and the second measurement area (Am2) can be 50 ㎛ or more.

When the surface roughness value on at least one side measured according to the above measurement method is 15 to 60 ㎛, not only is the generation of bubbles at the contact interface between the one side and another member such as a sealant suppressed, but also the adhesion can be further improved.

Hereinafter, each component included in the variable transmittance optical laminate of the present invention will be described in detail.

FIG. 4 is a diagram showing a laminated structure of a variable transmittance optical laminate according to one embodiment of the present invention, and FIG. 5 is a diagram showing a laminated structure of a polarizing plate according to one or more embodiments of the present invention.

Referring to FIG. 4, a variable transmittance optical laminate according to an embodiment of the present invention may include a first polarizing plate (100-1), a second polarizing plate (100-2), a first transparent conductive layer (200-1), a second transparent conductive layer (200-2), and a liquid crystal layer (300).

Referring to FIG. 5, the polarizing plate (100) includes a polarizer (110), and may further include functional layers, such as a protective layer (120), a phase difference adjustment layer (130), and a refractive index adjustment layer (140), on one or both sides of the polarizer (110). For example, the polarizing plate (100) may include a polarizer (110) and a protective layer (120) laminated on one or both sides of the polarizer (110) (see FIGS. 5a and 5b), may include a polarizer (110), a protective layer (120) laminated on one side of the polarizer (110), and a phase difference adjustment layer (130) laminated on the other side of the polarizer (110) opposite the one side (see FIG. 5c), may include a polarizer (110), a protective layer (120) laminated on one side of the polarizer, and a phase difference adjustment layer (130) and a refractive index adjustment layer (140) sequentially laminated on the other side of the polarizer (110) opposite the one side (see FIG. 5d), and may include a polarizer (110), a protective layer (120) laminated on one side of the polarizer, and a phase difference adjustment layer (130) and a refractive index adjustment layer (140) laminated on the other side of the polarizer (110) opposite the one side (see FIG. 5d). It may include a protective layer (120) and a phase difference adjustment layer (130) sequentially laminated on the other surface opposite to the one surface of the polarizer (110) (see FIG. 5e).

The above polarizer (110) may use a polarizer developed in the past or later, and for example, a stretchable polarizer or a coated polarizer may be used.

In one embodiment, the stretchable polarizer may include a stretched polyvinyl alcohol (PVA) resin. The polyvinyl alcohol (PVA) resin may be a polyvinyl alcohol resin obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable therewith. The other monomer may be an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, an olefin monomer, a vinyl ether monomer, an acrylamide monomer having an ammonium group, or the like. In addition, the polyvinyl alcohol (PVA) resin may include a modified one, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes.

In one embodiment, the coated polarizer can be formed by a liquid crystal coating composition, wherein the liquid crystal coating composition can include a reactive liquid crystal compound and a dichroic dye, etc.

The above reactive liquid crystal compound may refer to a compound including, for example, a mesogen skeleton and also including one or more polymerizable functional groups. Such reactive liquid crystal compounds are known in various ways under the name of so-called RM (Reactive Mesogen). The above reactive liquid crystal compound can form a cured film in which a polymer network is formed while maintaining the liquid crystal arrangement by polymerization by light or heat.

The above reactive liquid crystal compound may be a monofunctional or polyfunctional reactive liquid crystal compound. The monofunctional reactive liquid crystal compound may refer to a compound having one polymerizable functional group, and the polyfunctional reactive liquid crystal compound may refer to a compound having two or more polymerizable functional groups.

The above-mentioned dichroic dye is a component that is included in a liquid crystal coating composition and provides polarization properties, and has different absorbances in the long axis direction and the short axis direction of the molecule. The above dichroic dye may be a dichroic dye that has been developed in the past or will be developed in the future, and may include, for example, at least one selected from the group consisting of azo dyes, anthraquinone dyes, perylene dyes, merocyanine dyes, azomethine dyes, phthaloperylene dyes, indigo dyes, dioxadine dyes, polythiophene dyes, and phenoxazine dyes.

The liquid crystal coating composition may further include a solvent capable of dissolving the reactive liquid crystal compound and the dichroic dye, and examples thereof include propylene glycol monomethyl ether acetate (PGMEA), methyl ethyl ketone (MEK), xylene, and chloroform. In addition, the liquid crystal coating composition may further include a leveling agent, a polymerization initiator, and the like, within a range that does not impair the polarization characteristics of the coating film.

The above protective layer (120) is intended to preserve the polarization characteristics of the polarizer (110) from post-processing and external environments, and can be implemented in the form of a protective film, etc.

The protective layer (120) may be formed by directly contacting one side or both sides of the polarizer (110) as shown in FIGS. 5A and 5B, but is not limited thereto. For example, the protective layer may be used as a multilayer structure in which one or more protective layers are continuously laminated, and may be formed by directly contacting one side or both sides of another functional layer.

In one or more embodiments, the protective layer (120) is 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). It may contain more than one type.

The above phase difference adjustment layer (130) is intended to complement the optical characteristics of the optical laminate, and can be implemented in the form of a phase difference film, etc., and a phase difference film, etc. that is conventionally or later developed can be used. 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 can be used, and these can be used alone or in combination.

The phase difference adjustment layer (130) may be formed in direct contact with one surface of the polarizer (110), as illustrated in FIGS. 5c and 5d, but is not limited thereto. For example, as illustrated in FIG. 5e, the phase difference adjustment layer (130) may be formed on one surface of the protective layer (120), so that the polarizer (110), the protective layer (120), and the phase difference adjustment layer (130) are sequentially laminated.

The above phase difference control layer (130) can use a polymer film or a liquid crystal polymer film that is stretched in an appropriate manner to impart optical anisotropy through stretching.

In one embodiment, the polymer stretched film may use a polymer layer including a polyolefin such as polyethylene (PE) or polypropylene (PP), a cyclo olefin polymer (COP) such as polynorbornene, a polyester such as polyvinyl chloride (PVC), polyacrylonitrile (PAN), polysulfone (PSU), an acrylic resin, polycarbonate (PC), or polyethylene terephthalate (PET), a cellulose ester polymer such as polyacrylate, polyvinyl alcohol (PVA), or triacetyl cellulose (TAC), or a copolymer of two or more monomers among the monomers forming the polymer.

The method for obtaining the above polymer stretched film is not particularly limited, and for example, the polymer material can be formed into a film and then stretched. The method for forming into the film form is not particularly limited, and it is possible to form the film by known methods such as injection molding, sheet molding, blow molding, injection blow molding, inflation molding, extrusion molding, foam molding, and cast molding, and secondary processing molding methods such as pressure molding and vacuum molding can also be used. Among these, extrusion molding and cast molding are preferably used. At this time, for example, an extruder equipped with a T-die, a circular die, etc. can be used to extrusion mold an unstretched film. When obtaining a molded product by extrusion molding, a material in which various resin components, additives, etc. are melt-mixed in advance can be used, and it can also be molded by melt-mixing during extrusion molding. In addition, the unstretched film can be cast molded by dissolving various resin components using a solvent common to various resin components, such as chloroform or dimethylene chloride, and then casting and drying to solidify.

The above polymer stretched film can be stretched uniaxially in the mechanical direction (MD; mechanical direction, longitudinal direction or length direction) of the formed film, uniaxially in the direction perpendicular to the mechanical direction (TD; transverse direction, transverse direction or width direction), and can also be manufactured into a biaxially stretched film by stretching by a sequential biaxial stretching method of roll stretching and tenter stretching, a simultaneous biaxial stretching method by tenter stretching, a biaxial stretching method by tubular stretching, etc.

The above liquid crystal polymerization film may contain a reactive liquid crystal compound in a polymerized state. The reactive liquid crystal compound may be applied in the same manner as the reactive liquid crystal compound of the above-described coated polarizer.

In one or more embodiments, the thickness of the phase difference control layer (130) may be 10 ㎛ to 100 ㎛ in the case of a polymer stretched film, and 0.1 ㎛ to 5 ㎛ in the case of a liquid crystal polymer film.

The above refractive index control layer (140) is provided to compensate for the refractive index difference of the optical laminate due to the transparent conductive layer (200), and may serve to improve visibility characteristics, etc. by reducing the refractive index difference. In addition, the refractive index control layer (140) may be provided to correct the color caused by the transparent conductive layer (200). Meanwhile, when the transparent conductive layer has a pattern, the difference in transmittance between the pattern area where the pattern is formed and the non-pattern area where the pattern is not formed can be compensated for through the refractive index control layer (140).

Specifically, the transparent conductive layer (200) is laminated adjacent to another member (e.g., polarizer (110), etc.) having a different refractive index, and a difference in light transmittance may be induced due to the difference in refractive index with respect to the adjacent other layer, and in particular, when a pattern is formed in the transparent conductive layer, a problem may occur in that the pattern area and the non-pattern area are distinguishable and visible. Therefore, by including the refractive index control layer (140), the difference in light transmittance of the optical laminate can be reduced by compensating for the refractive index, and in particular, when a pattern is formed in the transparent conductive layer, the pattern area and the non-pattern area are not distinguished and visible.

In one embodiment, the refractive index of the refractive index control layer (140) may be appropriately selected depending on the material of the adjacent other member, but is preferably 1.4 to 2.6, and more preferably 1.4 to 2.4. In this case, light loss due to a sharp refractive index difference between the other member, such as the polarizer (110), and the transparent conductive layer (200) can be prevented.

The above refractive index control layer (140) is not particularly limited as long as it can prevent a sharp difference in refractive index between other components such as a polarizer (110) and the transparent conductive layer (200), and a compound used in the formation of a refractive index control layer that is conventionally or later developed can be used. For example, it can be formed from a refractive index control layer forming composition that includes a polymerizable isocyanurate compound.

In one embodiment, the polarizing plate (100) may further include, in addition to the functional layer described above, another functional layer to assist or enhance the characteristics of the polarizer, and for example, may further include an overcoat layer, etc. to further enhance mechanical durability.

In one or more embodiments, the polarizing plate (100) may have a thickness of 30 to 200 μm, preferably 30 to 170 μm, and more preferably 50 to 150 μm. In this case, the polarizing plate (100) can be used to manufacture an optical laminate having a thin thickness while maintaining optical properties.

The above transparent conductive layer (200) is provided for driving the liquid crystal layer (300) and may be formed in direct contact with the polarizing plate (100). For example, as illustrated in FIG. 4, the first transparent conductive layer (200-1) and the second transparent conductive layer (200-2) may be formed in direct contact with the first polarizing plate (100-1) and the second polarizing plate (100-2), respectively.

Conventionally, optical laminates used in the manufacture of smart windows and the like have been manufactured by forming a conductive layer for driving liquid crystals on one surface of a substrate and bonding the other surface of the substrate with a polarizing plate. However, the optical laminate with variable transmittance according to the present invention is characterized in that the thickness of the laminate is reduced while the transmittance and bending characteristics in the light transmission mode are improved by directly forming the conductive layer on one surface of a polarizing plate without including a separate substrate for forming the conductive layer.

In one embodiment, the transparent conductive layer (200) may be formed by being directly deposited on one surface of the polarizing plate (100). At this time, the transparent conductive layer (200) may be formed by directly contacting the surface of the polarizing plate (100) that has been pretreated after performing pretreatment such as corona treatment or plasma treatment on one surface of the polarizing plate (100) in order to improve adhesion to the polarizing plate (100). The pretreatment is not limited to corona treatment or plasma treatment, and any pretreatment process that is conventionally or later developed may be used within a range that does not harm the purpose of the present invention.

In another embodiment, the transparent conductive layer (200) may be formed in direct contact with the polarizing plate (100) with an adhesive-friendly layer (not shown) provided on one surface of the polarizing plate (100) interposed therebetween, in order to improve adhesion to the polarizing plate (100).

The above transparent conductive layer (200) preferably has a visible light transmittance of 50% or more, and may include, for example, at least one selected from the group consisting of transparent conductive oxides, metals, carbon-based materials, conductive polymers, conductive inks, and nanowires, but is not limited thereto, and any material of a transparent conductive layer developed in the past or later may be used.

In one or more embodiments, the transparent conductive oxide may include at least one 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), and zinc oxide (ZnO). In addition, the metal may include at least one 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, and may include, for example, a silver-palladium-copper (APC) alloy or a copper-calcium (CuCa) alloy. The above carbon-based material may include at least one selected from the group consisting of carbon nanotubes (CNTs) and graphene, and the conductive polymer may include at least one selected from the group consisting of polypyrrole, polythiophene, polyacetylene, PEDOT, and polyaniline. The conductive ink may be an ink in which a metal powder and a curable polymer binder are mixed, and the nanowire may be, for example, a silver nanowire (AgNW).

In addition, the transparent conductive layer (200) may be formed into a two-layer or more structure by combining the above materials. For example, it may be formed into a two-layer structure including a metal layer and a transparent conductive oxide layer to lower the reflectivity of incident light and increase the transmittance.

The above transparent conductive layer (200) can be formed by a method commonly used in the field, and for example, can be formed by selecting an appropriate process from among coating processes such as a spin coating method, a roller coating method, a bar coating method, a dip coating method, a gravure coating method, a curtain coating method, a die coating method, a spray coating method, a doctor coating method, and a kneader coating method; printing processes such as a screen printing method, a spray printing method, an inkjet printing method, a lithographic printing method, a plate printing method, and a flat printing method; and a deposition process such as a CVD (chemical vapor deposition), a PVD (physical vapor deposition), and a PECVD (plasma enhanced chemical vapor deposition).

The above liquid crystal layer (300) can change the driving mode of the optical laminate by controlling the transmittance of light incident from one or more directions depending on the electric field.

The above liquid crystal layer (300) may include a liquid crystal compound and may be positioned, for example, within a space provided by a sealant (600) and a spacer (not shown) provided between the first polarizing plate (100-1) and the second polarizing plate (100-2) in the light control region.

The above liquid crystal compound is not particularly limited as long as it is capable of controlling the light transmittance by being driven by an electric field, and a liquid crystal compound developed in the past or later can be used. For example, the content regarding the reactive liquid crystal compound of the above-described coated polarizer can be equally applied.

The liquid crystal behavior of the above liquid crystal layer (300) is not particularly limited, and for example, TN (Twisted nematic) mode, STN (Super twisted nematic) mode, VA (Vertical alignment) mode, etc. can be used.

The above sealant may include a curable resin as a base resin. As the base resin, an ultraviolet-curable resin or a thermosetting resin known in the art to be usable for a sealant may be used. The ultraviolet-curable resin may be a polymer of an ultraviolet-curable monomer. The thermosetting resin may be a polymer of a thermosetting monomer.

As the base resin of the sealant, for example, an acrylate-based resin, an epoxy-based resin, a urethane-based resin, a phenol-based resin, or a mixture of the above resins can be used. In one embodiment, the base resin can be an acrylate-based resin, and the acrylate-based resin can be a polymer of an acrylic monomer. The acrylic monomer can be, for example, a polyfunctional acrylate. In another embodiment, the sealant can further include a monomer component in the base resin. The monomer component can be, for example, a monofunctional acrylate. In the present specification, a monofunctional acrylate can mean a compound having one acrylic group, and a polyfunctional acrylate can mean a compound having two or more acrylic groups. The curable resin can be cured by irradiation with ultraviolet light and/or heating. The ultraviolet irradiation conditions or heating conditions can be appropriately performed within a range that does not impair the purpose of the present application. The sealant, if necessary, can further include an initiator, for example, a photoinitiator or a thermal initiator.

The above sealant can be formed by a method commonly used in the art, for example, by drawing the sealant onto the outer surface (i.e., the inactive area) of the liquid crystal layer using a dispenser having a nozzle.

The above spacer may include at least one of a ball spacer and a column spacer, and is particularly preferably a ball spacer. The ball spacer may be one or more, and is preferably 1 to 10 μm in diameter. In addition, when viewed in a planar direction, the area occupied by the ball spacer in the liquid crystal layer (300) is preferably 0.01 to 10% with respect to the area of the liquid crystal layer (300) in terms of user visibility and improved transmittance in a light-transmitting mode.

In one embodiment, the liquid crystal layer (300) may further include an alignment film (400) as needed, and may be formed on both sides of the liquid crystal layer (300) including a liquid crystal compound, for example.

The alignment film (400) is not particularly limited as long as it is for adding orientation to a liquid crystal compound. For example, the alignment film (400) can be manufactured by applying and curing an alignment film coating composition containing an orientation polymer, a photopolymerization initiator, and a solvent. The alignment polymer is not particularly limited, but a polyacrylate-based resin, a polyamic acid resin, a polyimide-based resin, a polymer containing a cinnamate group, etc. can be used, and a polymer capable of exhibiting orientation that is developed in the past or later can be used.

The optical laminate with variable transmittance of the present invention may further include other members within a range that does not impair the purpose of the present invention, for example, may further include a point-based adhesive layer, and may further include an ultraviolet absorbing layer, a hard coating layer, or the like.

The above-mentioned adhesive layer can be formed using an adhesive or a pressure-sensitive adhesive, and it is preferable that it have appropriate pressure-sensitive adhesive strength so that peeling, bubbles, etc. do not occur when handling the optical laminate, while also having transparency and thermal stability.

The above adhesive may be a conventional or later-developed adhesive, and for example, a photocurable adhesive may be used.

The above photocurable adhesive exhibits strong adhesive strength by being crosslinked and cured by receiving active energy rays such as ultraviolet (UV) rays and electron beams (EB), and may be composed of a reactive oligomer, a reactive monomer, a photopolymerization initiator, etc.

The above reactive oligomer is an important component that determines the properties of the adhesive, and forms a polymer bond through a photopolymerization reaction to form a cured film. Usable reactive oligomers include polyester resins, polyether resins, polyurethane resins, epoxy resins, polyacrylic resins, and silicone resins.

The above reactive monomer acts as a crosslinker and diluent of the above-mentioned reactive oligomer and affects the adhesive properties. The reactive monomers that can be used include monofunctional monomers, polyfunctional monomers, epoxy monomers, vinyl ethers, and cyclic ethers.

The above photopolymerization initiator plays a role in initiating photopolymerization by absorbing light energy to generate radicals or cations, and an appropriate one can be selected and used depending on the photopolymerization resin.

The adhesive may be a conventional or later-developed adhesive, and in one or more embodiments, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a urethane adhesive, a polyvinyl alcohol adhesive, a polyvinyl pyrrolidone adhesive, a polyacrylamide adhesive, a cellulose adhesive, a vinyl alkyl ether adhesive, or the like may be used. The adhesive is not particularly limited as long as it has adhesive strength and viscoelasticity, but in terms of ease of acquisition, etc., it may preferably be an acrylic adhesive, and may include, for example, a (meth)acrylate copolymer, a crosslinking agent, a solvent, or the like.

The crosslinking agent may be a crosslinking agent that has been developed in the past or will be developed in the future, and may include, for example, a polyisocyanate compound, an epoxy resin, a melamine resin, a urea resin, dialdehydes, a methylol polymer, etc., and preferably, a polyisocyanate compound.

The solvent may include a common solvent used in the field of resin compositions, and for example, alcohol compounds such as methanol, ethanol, isopropanol, butanol, and propylene glycol methoxy alcohol; ketone compounds such as methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, and dipropyl ketone; acetate compounds such as methyl acetate, ethyl acetate, butyl acetate, and propylene glycol methoxy acetate; cellosolve compounds such as methyl cellosolve, ethyl cellosolve, and propyl cellosolve; and hydrocarbon compounds such as hexane, heptane, benzene, toluene, and xylene. These solvents may be used alone or in combination of two or more.

The thickness of the above-described adhesive layer may be appropriately determined depending on the type of resin that acts as the adhesive, the 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, and more preferably 0.1 to 10 μm, in order to secure sufficient adhesive strength and minimize the thickness of the optical laminate.

The above UV absorbing layer is not particularly limited as long as it is for preventing deterioration of the optical laminate due to UV rays, and examples thereof include salicylic acid-based UV absorbers (phenyl salicylate, p-tert-butyl salicylate, etc.), benzophenone-based UV absorbers (2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, etc.), benzotriazole-based UV absorbers (2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthalimidemethyl)-5'-methylphenyl)benzotriazole, 2,2-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol), 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 branched dodecyl)-4-methylphenol, mixtures 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-based ultraviolet absorbers (2'-ethylhexyl-2-cyano-3,3-diphenylacrylate, ethyl-2-cyano-3-(3',4'-methylenedioxyphenyl)-acrylate, etc.), triazine-based ultraviolet absorbers, etc., can be used, and benzotriazole-based ultraviolet absorbers with high transparency and excellent effect in preventing deterioration of polarizing plates or transmittance variable layers, Triazine-based UV absorbers are preferred, and benzotriazole-based UV absorbers having a more appropriate spectral absorption spectrum are particularly preferred. The benzotriazole-based UV absorbers may be bis-based, and examples thereof include 6,6'-methylenebis(2-(2H-benzo[d][1,2,3]triazol-2-yl)-4-(2,4,4-trimethylpentan-2-yl)phenol), 6,6'-methylenebis(2-(2H-benzo[d][1,2,3]triazol-2-yl)-4-(2-hydroxyethyl)phenol), and the like.

The above hard coating layer is not particularly limited as long as it is for protecting components such as a polarizing plate and a variable transmittance layer from external physical or chemical impacts, and a hard coating layer developed previously or later may be used.

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

The photocurable compound and photoinitiator can be used without limitation as those commonly used in the art, for example, the photocurable compound can be a photopolymerizable monomer, a photopolymerizable oligomer, etc., and examples thereof include monofunctional and/or polyfunctional (meth)acrylates, and the photoinitiator can include oxime esters, etc.

The present invention includes, in addition to the above-described variable transmittance optical laminate, a smart window including the same, and FIG. 6 is a diagram showing a smart window according to an embodiment of the present invention.

Referring to FIG. 6, a smart window according to an embodiment of the present invention may include a transmittance variable optical laminate (10), a glass member (20) laminated on both sides of the transmittance variable optical laminate (10), and a sealant (30). The sealant (30) may be provided to form a contact interface with at least one side of the transmittance variable optical laminate (10), and preferably, may be formed on the upper and lower surfaces of the transmittance variable optical laminate (10) and provided between the transmittance variable optical laminate (10) and the glass member (20).

The above glass member (20) can be appropriately selected according to the user's needs, and for example, glass of 1 mm to 5 mm can be used.

The sealant (30) is not particularly limited as long as it can bond the optical laminate (10) with variable transmittance and the glass member (20) and protect the optical laminate (10) from the outside. For example, it may include a thermoplastic resin and have a single-layer or two-layer or more multi-layer structure.

The thermoplastic resin is not particularly limited, and it is possible to use a thermoplastic resin developed previously or later. The thermoplastic resin may be used alone, or two or more types may be used in combination.

In one or more embodiments, the thermoplastic resin may include polyvinyl acetal resin, ethylene-vinyl acetate copolymer resin, ethylene-acrylic acid copolymer resin, polyurethane resin, and polyvinyl alcohol resin, and preferably, it may be polyvinyl acetal resin, and the adhesive strength of the polyvinyl acetal resin may be further improved by combined use with a plasticizer.

The above polyvinyl acetal resin can be produced, for example, by acetalizing polyvinyl alcohol (PVA) with an aldehyde. The polyvinyl alcohol is obtained, for example, by drying polyvinyl acetate. The degree of saponification of the polyvinyl alcohol is generally in the range of 70 to 99.9 mol%.

The average degree of polymerization of the above polyvinyl alcohol (PVA) is preferably 200 or more, more preferably 500 or more, still more preferably 1500 or more, further preferably 1600 or more, particularly preferably 2600 or more, most preferably 2700 or more, preferably 5000 or less, more preferably 4000 or less, and still more preferably 3500 or less. When the average degree of polymerization is equal to or greater than the lower limit, the penetration resistance of the glass member is further increased. When the average degree of polymerization is equal to or less than the upper limit, the molding of the sealant is facilitated.

The average degree of polymerization of the above polyvinyl alcohol is obtained by a method compliant with JIS K6726 “Test method for polyvinyl alcohol.”

The carbon number of the acetal group included in the above polyvinyl acetal resin is not particularly limited. The aldehyde used when producing the above polyvinyl acetal resin is not particularly limited. The carbon number of the acetal group in the above polyvinyl acetal resin is preferably 3 to 5, and more preferably 3 or 4. When the carbon number of the acetal group in the above polyvinyl acetal resin is 3 or more, the glass transition temperature of the sealant is sufficiently lowered.

The above aldehyde is not particularly limited. Generally, an aldehyde having 1 to 10 carbon atoms is preferably used. As the aldehyde having 1 to 10 carbon atoms, for example, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, 2-ethylbutyraldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde, n-decylaldehyde, formaldehyde, acetaldehyde, and benzaldehyde can be mentioned. Propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde or n-valeraldehyde is preferable, propionaldehyde, n-butyraldehyde or isobutyraldehyde is more preferable, and n-butyraldehyde is still more preferable. The above aldehydes may be used alone or in combination of two or more.

The hydroxyl group content (hydroxyl group amount) of the above polyvinyl acetal resin is preferably 15 mol% or more, more preferably 18 mol% or more, preferably 40 mol% or less, and more preferably 35 mol% or less. When the hydroxyl group content is equal to or greater than the lower limit, the adhesive strength of the sealant is further increased. Furthermore, when the hydroxyl group content is equal to or less than the upper limit, the flexibility of the sealant is increased, making it easier to handle the sealant.

The hydroxyl group content of the above polyvinyl acetal resin is a value expressed as a percentage of the mole fraction obtained by dividing the amount of ethylene groups to which hydroxyl groups are bonded by the total amount of ethylene groups in the main chain. The amount of ethylene groups to which hydroxyl groups are bonded can be measured, for example, in accordance with JIS K6728 “Test method for polyvinyl butyral.”

The acetylation degree (acetyl group amount) of the above polyvinyl acetal resin is preferably 0.1 mol% or more, more preferably 0.3 mol% or more, even more preferably 0.5 mol% or more, preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 20 mol% or less. When the acetylation degree is equal to or greater than the lower limit, the compatibility of the polyvinyl acetal resin and the plasticizer increases. When the acetylation degree is equal to or less than the upper limit, the moisture resistance of the sealant and the laminated glass increases.

The above acetylation degree is a value expressed as a percentage of the mole fraction obtained by dividing the amount of ethylene groups to which acetyl groups are bonded by the total amount of ethylene groups in the main chain. The amount of ethylene groups to which acetyl groups are bonded can be measured, for example, in accordance with JIS K6728 “Test method for polyvinyl butyral.”

The degree of acetalization of the above polyvinyl acetal resin (the degree of butyralization in the case of polyvinyl butyral resin) is preferably 60 mol% or more, more preferably 63 mol% or more, preferably 85 mol% or less, more preferably 75 mol% or less, and even more preferably 70 mol% or less. When the degree of acetalization is equal to or greater than the lower limit, the compatibility of the polyvinyl acetal resin and the plasticizer increases. When the degree of acetalization is equal to or less than the upper limit, the reaction time required to produce the polyvinyl acetal resin is shortened.

The above acetalization degree is a value expressed as a percentage of the mole fraction obtained by subtracting the amount of ethylene groups bonded to hydroxyl groups and the amount of ethylene groups bonded to acetyl groups from the total amount of ethylene groups in the main chain and dividing the result by the total amount of ethylene groups in the main chain.

In addition, it is preferable that the content of hydroxyl groups (hydroxyl group amount), the degree of acetalization (degree of butyralization), and the degree of acetylation be calculated from the results measured by a method compliant with JIS K6728 "Test method for polyvinyl butyral". However, measurement according to ASTM D1396-92 may be used. When the polyvinyl acetal resin is a polyvinyl butyral resin, the content of hydroxyl groups (hydroxyl group amount), the degree of acetalization (degree of butyralization), and the degree of acetylation can be calculated from the results measured by a method compliant with JIS K6728 "Test method for polyvinyl butyral".

In one embodiment, in order to further improve the adhesive strength of the sealant, it is preferable to include a plasticizer. When the thermoplastic resin included in the sealant is a polyvinyl acetal resin, it is particularly preferable that the sealant include a plasticizer. It is preferable that the layer including the polyvinyl acetal resin include a plasticizer.

The above plasticizer is not particularly limited. As the above plasticizer, a conventionally known plasticizer can be used. The above plasticizer may be used alone or in combination of two or more types.

In addition, the present invention includes 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, and a window for a building including the smart window.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and these embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the invention of the scope of the invention, and the present invention is defined only by the scope of the claims.

Examples and Comparative Examples: Manufacturing Smart Windows

Smart windows of examples and comparative examples were each manufactured by forming a sealant (polyvinyl butyral (PVB)) on one side of the optical laminate, the surface roughness values of which satisfy Table 1 below.

Example Comparative example 1 2 3 4 5 1 2 3 Surface roughness value 16 ㎛ 24 ㎛ 38 ㎛ 47 ㎛ 56 ㎛ 13 ㎛ 61 ㎛ 130 ㎛

Experimental example

(1) Roughness measurement

The surface roughness was calculated as the average value of the maximum height difference for each of the 8 points in total, of each vertex area (a total of 4 points) and the midpoint area of the vertices (a total of 4 points) of a 200 μm x 200 μm area on one side of the optical laminate used as an example and comparative example, and is shown in Table 1 above.

(2) Evaluation of bubble generation

The contact interface between one side of the optical laminate used in the examples and comparative examples and the sealant was evaluated using an optical microscope (MX61, OLYMPUS) to determine whether bubbles were generated, and the results are shown in Table 2 below.

<Evaluation criteria>

○: No bubbles

X: Bubbles appear

(3) Adhesion evaluation

A 67 g ball was dropped at an angle of 90 degrees using a ball drop impact tester (TW-A18) to apply an impact to one side of the smart window of the above examples and comparative examples. At this time, the end after the impact was confirmed with an optical microscope (MX61, OLYMPUS), and the distance (cm) the ball moved until the laminated structure was separated was measured, and the results are shown in Table 2 below.

Example Comparative example 1 2 3 4 5 1 2 3 Bubble generation evaluation ○ ○ ○ ○ ○ ○ X X Adhesion Evaluation 40 50 60 70 70 10 - -

Referring to Table 2 above, in the case of the smart window of the embodiment in which the surface roughness value on one side of the optical laminate satisfies 15 to 60 ㎛, no bubbles are generated between the contact interface between the one side of the optical laminate and the sealant, and it can be seen from the adhesion evaluation result that separation occurred when a ball was dropped from a height of at least 40 cm.

Meanwhile, in the case of the smart window of Comparative Example 1 in which the surface roughness value on one side of the optical laminate is less than 15 ㎛, no bubbles were generated between the contact interface between the one side of the optical laminate and the sealant, but the adhesion evaluation result showed that separation occurred when a ball was dropped from a height of 10 cm or more. In addition, in the case of the smart windows of Comparative Examples 2 and 3 in which the surface roughness value on one side of the optical laminate exceeds 60 ㎛, it was found that a large number of bubbles were generated between the contact interface between the one side of the optical laminate and the sealant.

Therefore, it can be seen that when the surface roughness on one side of the optical laminate has a value of 15 to 60 ㎛, the adhesive strength is not reduced while no bubbles are generated between the contact interface between the one side of the optical laminate and the sealant.

Claims (17)

1st polarizing plate;
A first transparent conductive layer formed on one surface of the first polarizing plate;
A second polarizing plate opposite to the first polarizing plate;
A second transparent conductive layer formed on one side of the second polarizing plate and facing the first transparent conductive layer; and
A transmittance variable optical laminate comprising a liquid crystal layer provided between the first transparent conductive layer and the second transparent conductive layer,
At least one of the first transparent conductive layer and the second transparent conductive layer is formed in direct contact with one of the first polarizing plate and the second polarizing plate,
A transmittance variable optical laminate, wherein the above-mentioned transmittance variable optical laminate comprises one side surface which is a lateral side wall portion in the y-axis direction with respect to the plane direction, and wherein the surface roughness value on at least the one side surface is 15 to 60 ㎛.
A transmittance variable optical laminate according to claim 1, wherein the surface roughness value is an average value of the maximum height difference for each of a plurality of measurement areas on the one side.
A transmittance variable optical laminate according to claim 2, wherein the maximum height difference is a value measured in the height direction as the distance between the highest peak and the lowest valley of a roughness curve within a measurement area.
A variable transmittance optical laminate according to claim 2, wherein the distance between points indicating the maximum height difference for each of the plurality of measurement areas is 50 μm or more.
A transmittance variable optical laminate according to claim 1, wherein at least one of the first transparent conductive layer and the second transparent conductive layer is formed in direct contact with one of the first polarizing plate and the second polarizing plate without including a separate substrate therebetween.
A transmittance variable optical laminate according to claim 1, wherein at least one of the first transparent conductive layer and the second transparent conductive layer is formed in direct contact with one of the first and second polarizing plates, and includes an adhesive-friendly layer therebetween.
A transmittance variable optical laminate according to claim 1, wherein at least one of the first transparent conductive layer and the second transparent conductive layer comprises at least one selected from the group consisting of transparent conductive oxides, metals, carbon-based materials, conductive polymers, conductive inks, and nanowires.
A transmittance variable optical laminate according to claim 1, wherein at least one of the first polarizing plate and the second polarizing plate includes at least one functional layer selected from the group consisting of a protective layer, a phase difference control layer, and a refractive index control layer.
A transmittance variable optical laminate according to claim 1, wherein at least one of the first polarizing plate and the second polarizing plate has a thickness of 30 to 200 μm.
A transmittance variable optical laminate according to claim 1, wherein the liquid crystal layer includes at least one selected from the group consisting of a ball spacer and a column spacer.
In claim 10, the ball spacer is a transmittance variable optical laminate having a diameter of 1 to 10 μm.
A transmittance variable optical laminate according to claim 10, wherein the occupied area of the ball spacer within the liquid crystal layer is 0.01% to 10% of the area of the liquid crystal layer.
A method for manufacturing a variable transmittance optical laminate according to any one of claims 1 to 12.
A smart window comprising a variable transmittance optical laminate according to any one of claims 1 to 12.
A smart window according to claim 14, wherein the smart window comprises a sealant configured to form a contact interface with at least one side of the variable transmittance optical laminate.
A vehicle having the smart window of claim 14 applied to at least one of a front window, a rear window, a side window, a sunroof window, and an interior partition.
A window for a building, comprising a smart window of claim 14.