Optical device

Abstract

The present application relates to an optical device. The optical device of the present application can ensure structural stability and good quality uniformity by properly maintaining the cell gap of a liquid crystal element, having excellent adhesion between an upper substrate and a lower substrate, and minimizing defects such as extrusion or aggregation during the lamination process of an outer substrate.

Description

Technical Field

[0001] The present application relates to optical devices.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0142093, filed on October 29, 2020, the disclosure of which is incorporated herein by reference in its entirety. Background Art

[0003] For long-term stability and large-area scalability of a liquid crystal cell using a flexible substrate, it is important to maintain a cell gap between upper and lower substrates and impart adhesion between the upper and lower substrates.

[0004] Non-Patent Document 1 ("Tight Bonding of Two Plastic Substrates for Flexible LCDs," SID Symposium Digest, 38, pp. 653-656 (2007)) discloses a technique for forming an organic film pattern in the form of pillars or walls having a cell gap height on one substrate and affixing it to an opposing substrate using an adhesive. However, in this technique, the adhesive must be located only on the pillar or wall surfaces, but micro-stamping the adhesive on the pillar or wall surfaces is a highly complex process. Controlling the adhesive thickness and area is difficult. There is a high probability that the adhesive will be pushed out during lamination of the upper and lower substrates. Furthermore, there is a risk that the adhesive may contaminate the alignment film or liquid crystal. Summary of the Invention

[0005] Technical issues

[0006] To maintain the cell gap of the liquid crystal cell and ensure adhesion between the upper and lower substrates, it is possible to form a spacer and an alignment film on the lower substrate, and a pressure-sensitive adhesive layer with both liquid crystal alignment and adhesion on the upper substrate, followed by lamination. However, due to the very low modulus of the pressure-sensitive adhesive layer, such a structure is susceptible to external pressure, making it difficult to achieve good appearance quality under high temperature and high pressure during the autoclave process. Specifically, when the structural stability of the liquid crystal cell cannot be ensured during the autoclave process, defects such as cell gap collapse or liquid crystal flow / aggregation may occur, resulting in a decrease in the electro-optical properties and appearance uniformity of the liquid crystal cell.

[0007] The present application provides an optical device that can ensure structural stability and good quality uniformity by appropriately maintaining the cell gap of a liquid crystal cell, having excellent adhesion between an upper substrate and a lower substrate, and minimizing defects such as extrusion or aggregation.

[0008] Technical Solution

[0009] Among the physical properties mentioned in this specification, when the measurement temperature affects the result, unless otherwise stated, the relevant physical properties are physical properties measured at room temperature. The term room temperature is a natural temperature without heating or cooling, which is generally a temperature in the range of about 10°C to 30°C, or about 23°C or about 25°C. In addition, unless otherwise stated in the specification, the unit of temperature is °C. Among the physical properties mentioned in this specification, when the measurement pressure affects the result, unless otherwise stated, the relevant physical properties are physical properties measured under normal pressure. The term normal pressure is a natural pressure without pressurization or decompression, wherein generally about 1 atmosphere is referred to as normal pressure.

[0010] The present application relates to optical devices. Figure 1 The optical device of the present application is shown as an example. Figure 1 As shown, the optical device may include a first outer substrate 100a, a second outer substrate 100b disposed opposite to the first outer substrate 100a, and a liquid crystal element 300 positioned between the first outer substrate and the second outer substrate. The optical device may include at least one or more intermediate layers positioned between the first outer substrate and the liquid crystal element and between the second outer substrate and the liquid crystal element. Figure 1 An optical device including intermediate layers 200 a , 200 b positioned between a first outer substrate 100 a and a liquid crystal element 300 and between a second outer substrate 100 b and a liquid crystal element 300 , respectively, is exemplarily shown.

[0011] The first outer substrate and the second outer substrate may each independently be an inorganic substrate or a plastic substrate. Any known inorganic substrate may be used as the inorganic substrate without any particular limitation. In one example, a glass substrate having excellent light transmittance may be used as the inorganic substrate. Examples of glass substrates include, but are not limited to, soda-lime glass substrates, general tempered glass substrates, borosilicate glass substrates, and alkali-free glass substrates. As the polymer substrate, a cellulose film such as TAC (triacetyl cellulose) or DAC (diacetyl cellulose); a COP (cyclic olefin copolymer) film such as a norbornene derivative; an acrylic film such as Pac (polyacrylate) or PMMA (poly(methyl methacrylate)); a PC (polycarbonate) film; a polyolefin film such as PE (polyethylene) or PP (polypropylene); a PVA (polyvinyl alcohol) film; a PI (polyimide) film; a sulfone-based film such as PSF (polysulfone) film, PPS (polyphenylsulfone) film or PES (polyethersulfone) film; a PEEK (polyetheretherketone) film; a PEI (polyetherimide) film; a polyester-based film such as PEN (polyethylene naphthalate) film or PET (polyethylene terephthalate) film; or a fluororesin film, etc. can be used, but are not limited thereto. In each of the first outer substrate and the second outer substrate, a coating of gold, silver, or a silicon compound (eg, silicon dioxide or silicon monoxide), or a functional layer such as an antireflection layer may also be present as needed.

[0012] In one example, the first outer substrate and / or the second outer substrate can be a glass substrate. In order to overcome the physical limitations of liquid crystal cell, in the automotive industry or window industry, glass substrates can be laminated to the both sides of liquid crystal cell, or glass substrates can be laminated to one side of liquid crystal cell and film substrates can be laminated to the other side of liquid crystal cell. In its automotive industry, it is necessary to laminate glass substrates to the method for the both sides of liquid crystal cell by an adhesive layer. However, liquid crystal cell is easily affected by external pressure due to the use of a pressure-sensitive adhesive layer, so in a glass substrate lamination process such as an autoclave under high temperature and high pressure, defects such as cell gap collapse or the flow or aggregation of liquid crystal may occur. According to the present invention, as described below, the thickness of the control intermediate layer can minimize defects, and it is possible to ensure structural stability and quality uniformity of the optical device.

[0013] The first outer substrate and the second outer substrate can each have a thickness of about 0.3 mm or greater. In another example, the thickness can be about 0.5 mm or greater, 1 mm or greater, 1.5 mm or greater, or about 2 mm or greater, and can also be about 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, or about 3 mm or less.

[0014] The first outer substrate and the second outer substrate can be a flat substrate, or can be a substrate with a curved surface shape. For example, the first outer substrate and the second outer substrate can be a flat substrate at the same time, and have a curved surface shape at the same time, or either one can be a flat substrate and the other can be a substrate with a curved surface shape. In addition, at this, when having a curved surface shape at the same time, each curvature or radius of curvature can be the same or different. In this specification, curvature or radius of curvature can be measured in a manner known in the industry, and for example, non-contact equipment such as 2D profile laser sensor, color confocal line sensor or 3D measurement confocal microscope can be used to measure. The method of using such equipment to measure curvature or radius of curvature is known.

[0015] Regarding the first outer substrate and the second outer substrate, for example, when the curvature or curvature radius on the front surface and the back surface are different, the corresponding curvature or curvature radius of the opposing surfaces, that is, the curvature or curvature radius of the surface facing the second outer substrate in the case of the first outer substrate and the curvature or curvature radius of the surface facing the first outer substrate in the case of the second outer substrate, can be used as a reference. In addition, when the relevant surfaces have a portion where the curvature or curvature radius is not constant and varies, the maximum curvature or curvature radius can be used as a reference, or the minimum curvature or curvature radius can be used as a reference, or the average curvature or average curvature radius can be used as a reference.

[0016] The first outer substrate and the second outer substrate may each have a curvature or curvature radius difference within about 10%, within 9%, within 8%, within 7%, within 6%, within 5%, within 4%, within 3%, within 2% or within about 1%. When the large curvature or curvature radius is CL and the small curvature or curvature radius is CS, the curvature or curvature radius difference is a value calculated by 100% × (CL-CS) / CS. In addition, the lower limit of the curvature or curvature radius difference is not particularly limited. Since the curvature or curvature radius difference of the first outer substrate and the second outer substrate can be the same, the curvature or curvature radius difference can be about 0% or greater, or greater than about 0%. Such curvature or curvature radius control is useful in a structure in which a liquid crystal element contacts an intermediate layer in an optical device such as the present application. That is, when the difference in curvature or curvature radius exceeds 10%, when the outer substrate and the liquid crystal cell are in contact with the intermediate layer to be described below, the bonded outer substrate may be separated due to deterioration of the bonding force. However, if it is controlled within 10%, the problem of separation of the bonded outer substrate due to deterioration of the bonding force can be effectively prevented.

[0017] The first outer substrate and the second outer substrate may have the same curvature sign. In other words, the first outer substrate and the second outer substrate may be curved in the same direction. That is, in the above case, the center of curvature of the first outer substrate and the center of curvature of the second outer substrate are both present in the same portion of the upper and lower portions of the first outer substrate and the second outer substrate. When the first outer substrate and the second outer substrate are curved in the same direction, the first outer substrate and the second outer substrate can be more effectively bonded through the intermediate layer, and after bonding, the first outer substrate and the second outer substrate can be more effectively prevented from deteriorating in bonding strength with the liquid crystal cell and / or polarizer.

[0018] The specific range of each curvature or curvature radius of the first outer substrate and the second outer substrate is not particularly limited. In one example, the curvature radius of each of the first outer substrate and the second outer substrate may be about 100R or greater, 200R or greater, 300R or greater, 400R or greater, 500R or greater, 600R or greater, 700R or greater, 800R or greater, or about 900R or greater, or may be about 10,000R or less, 9,000R or less, 8,000R or less, 7,000R or less , 6,000R or less, 5,000R or less, 4,000R or less, 3,000R or less, 2,000R or less, 1,900R or less, 1,800R or less, 1,700R or less, 1,600R or less, 1,500R or less, 1,400R or less, 1,300R or less, 1,200R or less, 1,100R or less, or about 1,050R or less. Here, R means the curvature of a circle with a radius of 1 mm. Thus, here, for example, 100R is the curvature of a circle with a radius of 100 mm or the radius of curvature of such a circle. The first outer substrate and the second outer substrate may have the same or different radii of curvature within the above range. In one example, when the curvatures of the first outer substrate and the second outer substrate are different from each other, the radius of curvature of the substrate with the larger curvature may be within the above range. In one example, when the curvatures of the first and second outer substrates are different, the substrate with the greater curvature may be positioned in the direction of gravity when the optical device is used. When the curvatures or curvature radii of the first and second outer substrates are controlled as described above, even if the adhesive force caused by the intermediate layer to be described below is reduced, the net force, which is the sum of the restoring force and gravity, can prevent widening.

[0019] In one example, the optical device may not include a polarizer between the first outer substrate and the liquid crystal cell and between the second outer substrate and the liquid crystal cell. In another example, the optical device may further include a polarizer in at least one position between the first outer substrate and the liquid crystal cell and between the second outer substrate and the liquid crystal cell.

[0020] In this specification, the term polarizer means a film, sheet, or element having a polarization function. A polarizer is a functional element capable of extracting light vibrating in one direction from incident light vibrating in multiple directions.

[0021] The polarizer may be an absorptive polarizer or a reflective polarizer. In this specification, an absorptive polarizer refers to an element that exhibits selective transmission and absorption properties relative to incident light. For example, a polarizer can transmit light vibrating in any direction of incident light vibrating in multiple directions and can absorb light vibrating in other directions. In this specification, a reflective polarizer refers to an element that exhibits selective transmission and reflection properties relative to incident light. For example, a polarizer can transmit light vibrating in any direction of incident light vibrating in multiple directions and can reflect light vibrating in other directions. According to one example of the present application, the polarizer may be an absorptive polarizer.

[0022] The polarizer may be a linear polarizer. In this specification, a linear polarizer refers to a case where the light selectively transmitted is linearly polarized light vibrating in any direction, and the light selectively absorbed or reflected is linearly polarized light vibrating in a direction perpendicular to the vibration direction of the linearly polarized light. In the case of an absorptive linear polarizer, the light transmission axis and the light absorption axis may be perpendicular to each other. In the case of a reflective linear polarizer, the light transmission axis and the light reflection axis may be perpendicular to each other.

[0023] In one example, each polarizer can be a stretched polymer film dyed with iodine or an anisotropic dye. As a stretched polymer film, a PVA (poly (vinyl alcohol)) stretched film can be exemplified. In another example, each of the first polarizer and the second polarizer can be a guest-host polarizer, wherein a liquid crystal polymerized in an oriented state is a host and an anisotropic dye arranged according to the orientation of the liquid crystal is a guest. In another example, each polarizer can be a thermotropic liquid crystal film or a lyotropic liquid crystal film.

[0024] A protective film, an anti-reflection film, a retardation film, a pressure-sensitive adhesive layer, an adhesive layer, a surface treatment layer, etc. can be formed separately on one side or both sides of the polarizer. The retardation film can be, for example, a quarter wave plate or a half wave plate. The in-plane retardation value of the quarter wave plate to a light with a wavelength of 550nm can be in the range of about 100nm to 180nm, 100nm or 150nm. The in-plane retardation value of the half wave plate to a light with a wavelength of 550nm can be in the range of about 200nm to 300nm or 250nm to 300nm. The retardation film can be, for example, a stretched polymer film or a liquid crystal polymer film.

[0025] The transmittance of each polarizer to light with a wavelength of 550 nm may be in the range of 40% to 50%. The transmittance may refer to the single transmittance of the polarizer to light with a wavelength of 550 nm. The single transmittance of the polarizer can be measured using, for example, a spectrometer (V7100, manufactured by Jasco). For example, air is set as a baseline in a state where a polarizer sample (excluding the upper and lower protective films) is placed on the device, and each transmittance is measured in a state where the axis of the polarizer sample is vertically and horizontally aligned with the axis of the reference polarizer, and then the single transmittance can be calculated.

[0026] When it is assumed that the blocking state is achieved in the first orientation state of the liquid crystal element, the polarizer can be set in the optical device so that the angle formed by the average optical axis (the vector sum of the optical axes) of the first orientation state and the light absorption axis of the polarizer is about 80 degrees to about 100 degrees, or about 85 degrees to about 95 degrees, or is approximately perpendicular, or the polarizer can be set in the optical device so that the angle is 35 degrees to about 55 degrees, or about 40 degrees to about 50 degrees, or about 45 degrees.

[0027] Figure 2 The liquid crystal element is shown as an example. Figure 2 As shown, the liquid crystal element may include a first base layer 10a, a pressure-sensitive adhesive layer 10c formed on the inner side of the first base layer, a second base layer 20a arranged opposite to the first base layer 10a, a spacer 20c formed on the inner side of the second base layer 20a, and a liquid crystal layer 30 positioned between the first base layer 10a and the second base layer 20a.

[0028] As the first base layer and the second base layer, for example, an inorganic film such as a glass film, a crystalline silicon film or an amorphous silicon film or a quartz or ITO (Indium Tin Oxide) film, or a polymer film can be used, and in terms of realizing a flexible element, a polymer film can be used.

[0029] In one embodiment, the first base layer and the second base layer can each be a polymer film. As the polymer film, TAC (triacetyl cellulose); COP (cyclic olefin copolymer), such as a norbornene derivative; PMMA (poly(methyl methacrylate)); PC (polycarbonate); PE (polyethylene); PP (polypropylene); PVA (polyvinyl alcohol); DAC (diacetyl cellulose); Pac (polyacrylate); PES (polyethersulfone); PEEK (polyetheretherketone); PPS (polyphenylsulfone); PEI (polyetherimide); PEN (polyethylene naphthalate); PET (polyethylene terephthalate); PI (polyimide); PSF (polysulfone); PAR (polyarylate); or an amorphous fluororesin can be used, but are not limited thereto. In the first base layer and the second base layer, as needed, a coating of gold, silver, or a silicon compound (such as silicon dioxide or silicon monoxide), or a functional layer such as an antireflection layer can also be present.

[0030] The first base layer and the second base layer may each have a thickness of about 10 μm to about 1,000 μm. As another example, the thickness of the base layers may each be about 20 μm or more, 40 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, 120 μm or more, 140 μm or more, 160 μm or more, or about 180 μm or more, and may be about 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, or about 400 μm or less. When the thickness of the first base layer and the second base layer meets the above range, appearance defects such as wrinkles can be reduced when manufacturing an optical device by laminating a liquid crystal element with an outer substrate.

[0031] The pressure-sensitive adhesive layer may be present on the inner surface of the first base layer.In the present specification, the "inner surface" of the configuration included in the liquid crystal cell may mean a surface facing the liquid crystal layer.

[0032] The pressure-sensitive adhesive layer may be optically transparent and may have an average transmittance of about 80% or more, 85% or more, 90% or more, or 95% or more in the visible light region (eg, wavelength of 380 nm to 780 nm).

[0033] The pressure-sensitive adhesive layer can be a liquid crystal orientation pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer can be, for example, a vertically oriented pressure-sensitive adhesive layer or a horizontally oriented pressure-sensitive adhesive layer. In this specification, a "vertically oriented pressure-sensitive adhesive" can mean a pressure-sensitive adhesive having an attachment force that can bond the upper substrate and the lower substrate while imparting a vertical orientation force to the adjacent liquid crystal compounds. In this specification, a "horizontally oriented pressure-sensitive adhesive" can mean a pressure-sensitive adhesive having an attachment force that can bond the upper substrate and the lower substrate while imparting a horizontal orientation force to the adjacent liquid crystal compounds. The pretilt angle of the adjacent liquid crystal compounds relative to the vertically oriented pressure-sensitive adhesive can be in the range of 80 to 90 degrees, 85 to 90 degrees, or about 87 to 90 degrees, and the pretilt angle of the adjacent liquid crystal compounds relative to the horizontally oriented pressure-sensitive adhesive can be in the range of 0 to 10 degrees, 0 to 5 degrees, or 0 to 3 degrees.

[0034] In this specification, the pretilt angle may refer to the angle formed by the director of the liquid crystal compound relative to a plane horizontal to the liquid crystal alignment pressure-sensitive adhesive or alignment film in a state where no voltage is applied. In this specification, the director of the liquid crystal compound may refer to the optical axis or slow axis of the liquid crystal layer. Alternatively, when the liquid crystal compound has a rod-like shape, the director of the liquid crystal compound may refer to the long axis direction, and when the liquid crystal compound has a disc-like shape, the director of the liquid crystal compound may refer to the axis parallel to the normal direction of the disc plane.

[0035] The thickness of the pressure-sensitive adhesive layer may be, for example, in the range of 3 μm to 15 μm. When the thickness of the pressure-sensitive adhesive layer is within the above range, it is possible to minimize defects (such as squeezing or accumulation of the pressure-sensitive adhesive) when used to manufacture a liquid crystal cell while ensuring the adhesion between the upper substrate and the lower substrate.

[0036] As the pressure-sensitive adhesive layer, various types of pressure-sensitive adhesives known in the industry as OCA (Optically Clear Adhesives) can be appropriately used. Pressure-sensitive adhesives can be different from OCR (Optically Clear Resin) type adhesives that cure after the objects to be attached are bonded in that they cure before the objects to be attached are bonded. As the pressure-sensitive adhesive, for example, acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, or urethane-based pressure-sensitive adhesives can be applied.

[0037] The pressure-sensitive adhesive layer may include a cured product of a pressure-sensitive adhesive resin. In one example, the pressure-sensitive adhesive layer may include a silicone-based pressure-sensitive adhesive. The silicone pressure-sensitive adhesive may include a cured product of a curable silicone compound as the pressure-sensitive adhesive resin.

[0038] The type of the curable organic silicon compound is not particularly limited, and for example, a heat-curable organic silicon compound or an ultraviolet-curable organic silicon compound may be used. The curable organic silicon compound may be referred to as a pressure-sensitive adhesive resin.

[0039] In one example, the curable organosilicon compound can be an addition-curing organosilicon compound.

[0040] Specifically, addition-curable organosilicon compounds can be exemplified by, but not limited to, (1) organopolysiloxanes containing two or more alkenyl groups in the molecule and (2) organopolysiloxanes containing two or more silicon-bonded hydrogen atoms in the molecule. Such organosilicon compounds can form a cured product by, for example, an addition reaction in the presence of a catalyst to be described below.

[0041] More specific examples of the (1) organopolysiloxane that can be used in the present application may include: a dimethylsiloxane-methylvinylsiloxane copolymer terminated at both ends of the molecular chain with a trimethylsiloxane group, a methylvinylpolysiloxane terminated at both ends of the molecular chain with a trimethylsiloxane group, a dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer terminated at both ends of the molecular chain with a trimethylsiloxane group, a dimethylpolysiloxane terminated at both ends of the molecular chain with a dimethylvinylsiloxane group, a methylvinylpolysiloxane terminated at both ends of the molecular chain with a dimethylvinylsiloxane group, a dimethylsiloxane-methylvinylsiloxane copolymer terminated at both ends of the molecular chain with a dimethylvinylsiloxane group, a dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer terminated at both ends of the molecular chain with a dimethylvinylsiloxane group, 1 2SiO 1 / 2 The siloxane unit represented by R 1 2R 2 SiO 1 / 2 The siloxane units represented by SiO 4 / 2 The organopolysiloxane copolymer of siloxane units represented by R 1 2R 2 SiO 1 / 2 The siloxane units represented by SiO 4 / 2 The organopolysiloxane copolymer of siloxane units represented by R 1 R 2 SiO 2 / 2 The siloxane unit represented by R 1 SiO 3 / 2 The siloxane unit represented by R 2 SiO 3 / 2 The organopolysiloxane copolymers of siloxane units represented by, and mixtures of two or more of the foregoing, but not limited thereto.1 is a hydrocarbon group other than an alkenyl group, specifically, an alkyl group such as methyl, ethyl, propyl, butyl, pentyl, hexyl or heptyl; an aryl group such as phenyl, tolyl, xylyl or naphthyl; an aralkyl group such as benzyl or phenethyl; an alkyl group substituted with a halogen such as chloromethyl, 3-chloropropyl or 3,3,3-trifluoropropyl; and the like. In addition, herein, R 2 is an alkenyl group, which may specifically be a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, or the like.

[0042] More specific examples of the (2) organopolysiloxane that can be used in the present application may include: methylhydrogenpolysiloxane terminated with trimethylsiloxane groups at both ends of the molecular chain, dimethylsiloxane-methylhydrogen copolymer terminated with trimethylsiloxane groups at both ends of the molecular chain, dimethylsiloxane-methylhydrogensiloxane-methylphenylsiloxane copolymer terminated with trimethylsiloxane groups at both ends of the molecular chain, dimethylpolysiloxane terminated with dimethylhydrogensiloxane groups at both ends of the molecular chain, dimethylsiloxane-methylphenylsiloxane copolymer terminated with dimethylhydrogensiloxane groups at both ends of the molecular chain, methylphenylpolysiloxane terminated with dimethylhydrogensiloxane groups at both ends of the molecular chain, 1 3SiO 1 / 2 The siloxane unit represented by R 1 2HSiO 1 / 2 The siloxane units represented by SiO 4 / 2 The organopolysiloxane copolymer of siloxane units represented by R 1 2HSiO 1 / 2 The siloxane units represented by SiO 4 / 2 The organopolysiloxane copolymer of siloxane units represented by R 1 HSiO 2 / 2 The siloxane unit represented by R 1 SiO 3 / 2 Siloxane units represented by HSiO 3 / 2 The organopolysiloxane copolymers of siloxane units represented by, and mixtures of two or more of the foregoing, but not limited thereto. 1 is a hydrocarbon group other than an alkenyl group, which may specifically be an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group or a heptyl group; an aryl group such as a phenyl group, a tolyl group, a xylyl group or a naphthyl group; an aralkyl group such as a benzyl group or a phenethyl group; an alkyl group substituted with a halogen such as a chloromethyl group, a 3-chloropropyl group or a 3,3,3-trifluoropropyl group; and the like.

[0043] When pressure-sensitive adhesive layer is vertical orientation pressure-sensitive adhesive layer, the surface energy of pressure-sensitive adhesive can be 16mN / m or less.The lower limit of surface energy can be for example 5mN / m or more.When pressure-sensitive adhesive layer is horizontal orientation pressure-sensitive adhesive layer, surface energy can be greater than 16mN / m.The upper limit of surface energy can be for example 50mN / m or less.Surface energy can be measured using drop shape analyzer (KRUSS'DSA100 product).Specifically, repeat the process 5 times of contact angle obtained by dropping deionized water with known surface tension on the surface of pressure-sensitive adhesive, thereby obtain the mean value of five contact angle values of gained, similarly, repeat the process 5 times of contact angle obtained by dropping diiodomethane with known surface tension thereon, thereby obtain the mean value of five contact angle values of gained.Then, use the mean value of the contact angle of the deionized water and diiodomethane obtained to obtain surface energy by substituting the numerical value (Strom value) of the surface tension of solvent via Owens-Wendt-Rabel-Kaelble method. The surface energy (γ surface) of a sample can be calculated by considering the dispersion forces between non-polar molecules and the interaction forces between polar molecules (γ surface = γ dispersion + γ polarity), where the ratio of the polar term (γ polarity) in the surface energy γ surface can be defined as the polarity of the surface.

[0044] The upper and lower substrates of the liquid crystal cell can be attached to each other via a pressure-sensitive adhesive layer. Specifically, the pressure-sensitive adhesive layer of the upper substrate and the spacer of the lower substrate can be attached to each other. When an alignment film is formed on the spacer of the lower substrate, the region of the alignment film corresponding to the spacer can be attached to the pressure-sensitive adhesive layer of the upper substrate.

[0045] The storage elastic modulus of the pressure-sensitive adhesive layer may be 1 MPa or less. The lower limit of the storage elastic modulus of the pressure-sensitive adhesive layer may be, for example, 0.01 MPa or greater. Specifically, the storage elastic modulus (G2) of the pressure-sensitive adhesive layer may be 0.02 MPa or greater, 0.04 MPa, 0.06 MPa, 0.08 MPa or 0.1 MPa or greater, and may be 0.8 MPa or less, 0.6 MPa or less, 0.4 MPa or less, or 0.2 MPa or less. The storage elastic modulus may be a value measured at a temperature of 25°C and a frequency of 6 radians / second. In order to overcome the physical limitations of the liquid crystal cell, the outer substrates may be bonded together on both sides of the liquid crystal cell through an intermediate layer, but due to the low modulus of the pressure-sensitive adhesive layer, it is easily affected by external pressure, whereby defects such as cell gap collapse or liquid crystal flow or aggregation may occur. According to the present invention, as described below, the thickness of the intermediate layer included in the optical device is controlled, whereby defects may be minimized and the structural stability and quality uniformity of the optical device may be ensured.

[0046] The liquid crystal layer may include a liquid crystal compound. The liquid crystal compound may be one whose alignment direction can be changed by applying an external effect. In this specification, the term "external effect" may refer to any external factor that can affect the behavior of the material included in the liquid crystal layer, such as an external voltage. Therefore, a state without an external effect may refer to a state where no external voltage is applied.

[0047] The type and physical properties of the liquid crystal compound can be appropriately selected in consideration of the purpose of the present application. In one example, the liquid crystal compound can be a nematic liquid crystal or a smectic liquid crystal. Nematic liquid crystal can refer to a liquid crystal in which rod-shaped liquid crystal molecules are arranged in parallel in the long axis direction, although there is no regularity in their positions. Smectic liquid crystal can refer to a liquid crystal in which rod-shaped liquid crystal molecules are regularly arranged to form a layered structure and are regularly arranged in parallel in the long axis direction. According to one example of the present application, the liquid crystal compound can be a nematic liquid crystal compound.

[0048] As the nematic liquid crystal compound, such a liquid crystal compound can be selected: it has, for example, a clearing point of about 40°C or higher, about 50°C or higher, about 60°C or higher, about 70°C or higher, about 80°C or higher, about 90°C or higher, about 100°C or higher, or about 110°C or higher, or has a phase transition point within the above range (i.e., a phase transition point from a nematic phase to an isotropic phase). In one example, the clearing point or phase transition point may be about 160°C or lower, about 150°C or lower, or about 140°C or lower.

[0049] The liquid crystal compound may be a non-reactive liquid crystal compound. A non-reactive liquid crystal compound may refer to a liquid crystal compound that does not have a polymerizable group. The polymerizable group may be exemplified by, but is not limited to, an acryloyl group, an acryloyloxy group, a methacryloyl group, a methacryloyloxy group, a carboxyl group, a hydroxyl group, a vinyl group, or an epoxy group, and may include functional groups that are considered to be polymerizable groups.

[0050] The dielectric anisotropy of the liquid crystal compound may be positive or negative. The absolute value of the dielectric anisotropy of the liquid crystal compound may be appropriately selected in consideration of the purpose of the present application. The term "dielectric anisotropy (Δε)" may refer to the difference between the horizontal dielectric constant (ε / / ) and the vertical dielectric constant (ε / / ) of the liquid crystal. ⊥ ) difference (ε / / -ε ⊥ In this specification, the term horizontal dielectric constant (ε / / ) means a dielectric constant value measured along the electric field direction in a state where a voltage is applied so that the director of the liquid crystal and the direction of the electric field due to the applied voltage are substantially horizontal, and the vertical dielectric constant (ε ⊥) refers to the dielectric constant value measured along the electric field direction when a voltage is applied so that the director of the liquid crystal and the direction of the electric field caused by the applied voltage are substantially perpendicular. The dielectric anisotropy of the liquid crystal molecules may be in the range of 5 to 25.

[0051] The refractive index anisotropy of the liquid crystal compound can be appropriately selected in consideration of the purpose of the present application. In this specification, the term "refractive index anisotropy" may refer to the difference between the extraordinary refractive index and the ordinary refractive index of the liquid crystal compound. The refractive index anisotropy of the liquid crystal compound may be, for example, 0.01 to 0.3. The refractive index anisotropy may be 0.01 or greater, 0.05 or greater, or 0.07 or greater, and may be 0.3 or less, 0.2 or less, 0.15 or less, or 0.13 or less.

[0052] The liquid crystal layer may further include a dichroic dye. When the liquid crystal layer includes a dichroic dye, even if the liquid crystal cell includes a pressure-sensitive adhesive layer, cell gap fluctuations are less affected during the lamination process of the outer substrates. This has the advantage of allowing the thickness of the intermediate layer to be relatively thin, thereby ensuring structural stability and quality uniformity of the liquid crystal cell.

[0053] A dichroic dye can control the variable transmittance characteristics of the liquid crystal layer. In this specification, the term "dye" may refer to a material that can strongly absorb and / or deform light within at least a portion or all of the visible light region (for example, within the wavelength range of 400 nm to 700 nm), and the term "dichroic dye" may refer to a material that can anisotropically absorb light within at least a portion or all of the visible light region.

[0054] The liquid crystal layer containing a liquid crystal compound and a dichroic dye can be a GHLC layer (guest-host liquid crystal layer). In this specification, a "GHLC layer (guest-host liquid crystal layer)" can refer to a functional layer in which the dichroic dye is arranged together according to the arrangement of the liquid crystal compound, thereby exhibiting anisotropic light absorption characteristics relative to the alignment direction of the dichroic dye and the direction perpendicular to the alignment direction. For example, a dichroic dye is a substance whose light absorption rate varies with the polarization direction. If the absorption rate of light polarized in the long axis direction is large, it can be called a p-type dye, and if the absorption rate of light polarized in the short axis direction is large, it can be called an n-type dye. In one example, when a p-type dye is used, polarized light vibrating in the long axis direction of the dye can be absorbed, while polarized light vibrating in the short axis direction of the dye can be less absorbed and transmitted. In the following, unless otherwise specified, the dichroic dye is considered to be a p-type dye.

[0055] As the dichroic dye, for example, a known dye having a property of being able to align according to the orientation state of the liquid crystal compound by the so-called guest-host effect can be selected and used. Examples of such dichroic dyes include azo dyes, anthraquinone dyes, methine dyes, azomethine dyes, merocyanine dyes, naphthoquinone dyes, tetrazine dyes, phenylene dyes, quarterrylene dyes, benzothiadiazole dyes, diketopyrrolopyrrole dyes, squarylium dyes or pyromethene dyes, but the dyes applicable to the present application are not limited thereto.

[0056] As a dichroic dye, a dye having a dichroic ratio (i.e., a value obtained by dividing the absorption of polarized light parallel to the long axis direction of the dichroic dye by the absorption of polarized light parallel to the direction perpendicular to the long axis direction) of 5 or more, 6 or more, or 7 or more can be used. The dye can satisfy the dichroic ratio at at least part of or any wavelength within the wavelength range of the visible light region (e.g., within the wavelength range of about 380 nm to 700 nm or about 400 nm to 700 nm). The upper limit of the dichroic ratio can be, for example, about 20 or less, 18 or less, 16 or less, or about 14 or less.

[0057] The content of the dichroic dye in the liquid crystal layer can be appropriately selected in consideration of the purpose of the present application. For example, the content of the dichroic dye in the liquid crystal layer can be 0.2 wt% or greater. The content of the dichroic dye can specifically be 0.5 wt% or greater, 1 wt% or greater, 2 wt% or greater, or 3 wt% or greater. The upper limit of the content of the dichroic dye can be, for example, 10 wt% or less, 9 wt% or less, 8 wt% or less, 6 wt% or less, or 5 wt% or less. When the content of the dichroic dye in the liquid crystal layer is too low, it may be difficult to exhibit the desired variable transmittance characteristics, and it may not be sufficient to reduce the thickness of the intermediate layer to reduce the cell gap fluctuations that may occur during the lamination process of the outer substrate. At the same time, when the content of the dichroic dye in the liquid crystal layer is too high, there is a risk of precipitation. Therefore, it can be advantageous for the content of the dichroic dye to be within the above range.

[0058] The thickness of the liquid crystal layer is not particularly limited, and for example, the thickness of the liquid crystal layer may be about 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.5 μm or more, 1 μm or more, 1.5 μm or more, 2 μm or more, 2.5 μm or more, 3 μm or more, 3.5 μm or more, 4 μm or more, 4.5 μm or more, 5 μm or more, 5.5 μm or more, 6 μm or more, 6.5 μm or more, 7 μm or more, 7.5 μm or more, 8 μm or more, 8.5 μm or more, 9 μm or more, or 9.5 μm or more. The upper limit of the thickness of the liquid crystal layer is not particularly limited, and it may generally be about 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0059] The liquid crystal layer can switch between a first alignment state and a second alignment state different from the first alignment state. Switching can be regulated, for example, by applying external energy, such as a voltage. For example, the liquid crystal layer can maintain either the first alignment state or the second alignment state in the absence of an applied voltage, and can be switched to the other alignment state by applying a voltage.

[0060] In one example, the first alignment state can be a twisted alignment state. That is, by applying external energy, the liquid crystal layer can switch between a twisted alignment and an alignment state different from the twisted alignment. In this case, the optical device may not include polarizers between the first external substrate and the liquid crystal element, and between the second external substrate and the liquid crystal element. In one example, the liquid crystal layer can switch between a twisted alignment state and a vertical alignment state. In one example, when no voltage is applied, the liquid crystal layer can be in the twisted alignment state, and when a voltage is applied, it can be in the vertical alignment state.

[0061] In this specification, the "vertical alignment state" is a state in which the director of the liquid crystal compound in the liquid crystal layer is arranged approximately perpendicular to the plane of the liquid crystal layer, wherein, for example, the angle formed by the director of the liquid crystal compound relative to the plane of the liquid crystal layer can be, for example, in the range of about 80 degrees to 100 degrees or 85 degrees to 95 degrees, or it can form approximately 90 degrees.

[0062] In this specification, a "twisted orientation state" may refer to a helical structure in which the director of the liquid crystal compound in the liquid crystal layer forms a layer while twisting and aligning along an imaginary helical axis. The twisted orientation state can be realized in a vertical orientation state, a horizontal orientation state, or a tilted orientation state. That is, a vertical twisted orientation mode is a state in which a single liquid crystal compound forms a layer while twisting along the helical axis in a vertical orientation state; a horizontal twisted orientation mode is a state in which a single liquid crystal compound forms a layer while twisting along the helical axis in a horizontal orientation state; and a tilted twisted orientation mode is a state in which a single liquid crystal compound forms a layer while twisting along the helical axis in a tilted orientation state. According to the present application, the twisted orientation state may be a twisted orientation state of the horizontal orientation state.

[0063] In the twisted orientation state, the ratio (d / p) of the thickness (d) of the liquid crystal layer to the pitch (p) can be 20 or less, and the lower limit can be 0.5 or more. When the ratio (d / p) of the thickness (d) to the pitch (p) in the twisted orientation state is within the above range, the optical device can exhibit excellent variable transmittance characteristics even in the absence of any polarizer. Generally, when the ratio d / p is 0.7 or more and less than 2.5, it can be called an STN (super twisted nematic) mode, and when the ratio d / p is 2.5 or more, it can be called an HTN (highly twisted nematic) drive mode.

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

[0065] The liquid crystal layer may further include a chiral dopant. When the liquid crystal layer includes a chiral agent, a twisted orientation state may be achieved. The chiral agent (or chiral dopant) that may be included in the liquid crystal layer may be used without particular limitation, as long as it can cause the desired rotation (twist) without deteriorating the liquid crystal properties, such as nematic regularity. The chiral agent used to cause rotation in the liquid crystal compound needs to include at least chirality in the molecular structure. The chiral agent may be exemplified by: for example, a compound having one or two or more asymmetric carbons; a compound having an asymmetric point on a heteroatom, such as a chiral amine or a chiral sulfoxide; or a compound having axial asymmetry and an optically active site, such as a cumulative polyene or a binaphthol. The chiral agent may be, for example, a low molecular weight compound having a molecular weight of 1,500 or less. As a chiral agent, commercially available chiral nematic liquid crystals may also be used, for example, chiral dopant liquid crystal S811 commercially available from Merck Co., Ltd. or LC756 from BASF.

[0066] The application ratio of the chiral dopant is selected so as to achieve the desired ratio (d / p). Generally, the content (weight %) of the chiral dopant can be calculated using the formula 100 / HTP (helical twisting power) × pitch (p) (nm). HTP represents the twisting strength of the chiral dopant, wherein the content of the chiral dopant can be determined by taking into account the desired pitch according to the above method.

[0067] In another example, the first alignment state can be a horizontal alignment state. That is, the liquid crystal layer can be switched between a horizontal alignment and an alignment state different from the horizontal alignment by applying external energy. In one example, the liquid crystal layer can be switched between a horizontal alignment and a vertical alignment state. In one example, the liquid crystal layer can be in a horizontal alignment state when no voltage is applied, and in a vertical alignment state when a voltage is applied. In this case, the optical device can further include a polarizer between the first outer substrate and the liquid crystal element or between the second outer substrate and the liquid crystal element.

[0068] In this specification, the "horizontally aligned state" is a state in which the director of the liquid crystal compound in the liquid crystal layer is arranged approximately parallel to the plane of the liquid crystal layer, wherein, for example, the angle formed by the director of the liquid crystal compound relative to the plane of the liquid crystal layer can be, for example, in the range of about 0 degrees to 10 degrees or 0 degrees to 5 degrees, or it can form approximately about 0 degrees.

[0069] The liquid crystal element may further include a first electrode layer 10b formed on the inner surface of the first base layer 10a. In this case, the pressure-sensitive adhesive layer 10c may be present on the inner surface of the first electrode layer 10b. That is, the first electrode layer 10b may be present between the first base layer 10a and the pressure-sensitive adhesive layer 10c. The liquid crystal element may further include a second electrode layer 20b formed on the inner surface of the second base layer 20a. In this case, the spacer 20c may be present on the inner surface of the second electrode layer 20b. That is, the second electrode layer 20b may be present between the second base layer 20a and the spacer 20c.

[0070] The first electrode layer and the second electrode layer can be used to provide an external effect, such as the application of an electric field, so that the material contained in the liquid crystal layer transmits or blocks incident light. In one embodiment, the first electrode layer and / or the second electrode layer can include a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as ITO (indium tin oxide), but is not limited thereto. The upper second electrode layer and / or the lower second electrode layer can be formed by, for example, depositing a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as ITO (indium tin oxide).

[0071] The liquid crystal cell may further include an alignment film 20d on the inner surface of the second electrode layer 20b. A spacer 20c may be present between the second electrode layer 20b and the alignment film 20d. The alignment film may be formed on the spacer. That is, the top surface portion and / or the side surface portion of the spacer may contact the alignment film. The bottom surface of the spacer may contact the second electrode layer. Since the pressure-sensitive adhesive layer may have liquid crystal orientation characteristics, the alignment film may not be included on the inner surface of the first electrode layer. In one embodiment, the alignment film is not included on the inner surface of the first base layer.

[0072] In this specification, the combination of the first base layer, the first electrode layer, and the pressure-sensitive adhesive layer may be referred to as an upper substrate, and the combination of the second base layer, the second electrode layer, the spacer, and the alignment film may be referred to as a lower substrate. In a liquid crystal cell, the upper substrate may not include a separate alignment film in addition to the pressure-sensitive adhesive layer, and the lower substrate may include the alignment film.

[0073] The alignment film and the liquid crystal layer may be in contact with each other. The alignment film may be a vertical alignment film or a horizontal alignment film. In the present specification, "horizontal alignment film" may mean a layer comprising an alignment material that imparts a horizontal alignment force to the liquid crystal compounds present in the adjacent liquid crystal layer. In the present specification, "vertical alignment film" may mean a layer comprising an alignment material that imparts a vertical alignment force to the liquid crystal compounds present in the adjacent liquid crystal layer. The pretilt angle of the adjacent liquid crystal compounds relative to the vertical alignment film may be in the range of 80 to 90 degrees, 85 to 90 degrees, or about 87 to 90 degrees, and the pretilt angle of the adjacent liquid crystal compounds relative to the horizontal alignment film may be in the range of 0 to 10 degrees, 0 to 5 degrees, or 0 to 3 degrees. Unlike the pressure-sensitive adhesive layer, the alignment film may not have an adhesive force for bonding the upper substrate and the lower substrate. In one example, in Figure 2 In the state of the liquid crystal element, the alignment film can have a peeling force close to zero relative to the first base layer.

[0074] The alignment film can be a rubbed alignment film or a photo-aligned alignment film. The alignment direction of the alignment film can be the rubbing direction in the case of a rubbed alignment film, and can be the direction of the polarized light to be irradiated in the case of a photo-aligned film, wherein such an alignment direction can be determined by a detection method using an absorbing linear polarizer. Specifically, the alignment direction can be determined as follows: in a state where the liquid crystal compound contained in the liquid crystal layer is horizontally oriented, an absorbing linear polarizer is placed on one side of the liquid crystal layer, and the transmittance is measured while the polarizer is rotated 360 degrees. When light is irradiated on one side of the liquid crystal layer or the absorbing linear polarizer in the above state and the brightness (transmittance) is simultaneously measured from the other side, if the absorption axis or the transmission axis is consistent with the alignment direction of the liquid crystal alignment film, the transmittance tends to be low, wherein the alignment direction can be determined by simulation reflecting the refractive index anisotropy of the applied liquid crystal compound, etc. Methods for determining the alignment direction based on the pattern of the liquid crystal layer are known, and in the present application, the alignment direction of the alignment film can be determined by such known methods.

[0075] The alignment film may include one or more selected from the following: materials known to exhibit orientation ability through rubbing orientation, such as polyimide compounds, poly(vinyl alcohol) compounds, poly(amic acid) compounds, polystyrene compounds, polyamide compounds and polyoxyethylene compounds; or materials known to exhibit orientation ability through light irradiation, such as polyimide compounds, polyamic acid compounds, polynorbornene compounds, phenylmaleimide copolymer compounds, polyvinyl cinnamate compounds, polyazobenzene compounds, polyethyleneimide compounds, polyvinyl alcohol compounds, polyamide compounds, polyethylene compounds, polystyrene compounds, polyphenylene phthalamide compounds, polyester compounds, CMPI (chloromethylated polyimide) compounds, PVCI (polyvinylcinnamate) compounds and polymethyl methacrylate compounds, but are not limited thereto.

[0076] The spacer 20c may maintain a gap between the upper substrate and the lower substrate. A liquid crystal layer may exist in a region between the upper substrate and the lower substrate where no spacer exists.

[0077] The spacer may be a patterned spacer that maintains a gap between the first base layer and the second base layer. The spacer may have a column shape or a partition wall shape. The partition wall may divide the space between the lower substrate and the upper substrate into two or more spaces. In the area where the spacer is not present, other films or other layers present in the lower portion may be exposed. For example, the second electrode layer may be exposed in the area where the spacer is not present. The alignment film may cover the spacer and the second electrode layer exposed in the area where the spacer is not present. In a liquid crystal cell in which the upper substrate and the lower substrate are bonded together, the alignment film on the spacer of the lower substrate and the pressure-sensitive adhesive layer of the upper substrate may contact each other.

[0078] The liquid crystal compound and the above-mentioned additives (such as dichroic dyes, chiral agents, etc.) may be present in the region between the upper substrate and the lower substrate where no spacer exists. The shape of the spacer is not particularly limited, and it can be applied without limitation to a polyhedron having, for example, a circular, elliptical, or other polygonal shape.

[0079] The spacer may comprise a curable resin. The type of curable resin is not particularly limited, and for example, a thermosetting resin or a photocurable resin such as an ultraviolet curable resin may be used. As the thermosetting resin, for example, silicone resin, silicone resin, furan resin, polyurethane resin, epoxy resin, amino resin, phenol resin, urea resin, polyester resin, or melamine resin may be used, but is not limited thereto. As the ultraviolet curable resin, an acrylic polymer may generally be used, such as a polyester acrylate polymer, a polystyrene acrylate polymer, an epoxy acrylate polymer, a polyurethane acrylate polymer or a polybutadiene acrylate polymer, a silicone acrylate polymer or an alkyl acrylate polymer, but is not limited thereto.

[0080] The spacer can be formed by a patterning process. For example, the spacer can be formed by a photolithography process. The photolithography process may include applying a curable resin composition on a base layer or an electrode layer, and then irradiating it with ultraviolet light via a pattern mask. The pattern mask can be patterned into an ultraviolet-transmitting area and an ultraviolet-blocking area. The photolithography process may also include a process for washing the curable resin composition irradiated by ultraviolet light. The area irradiated by ultraviolet light is cured, and the area not irradiated by ultraviolet light remains in a liquid phase so that it is removed by a washing process, thereby patterning it into a partition wall shape. In the photolithography process, after ultraviolet irradiation, the pattern mask can be subjected to a release treatment to easily separate the resin composition and the pattern mask, or a release paper can be placed between the layer of the resin composition and the pattern mask.

[0081] The width (line width), spacing (pitch), thickness and area of the spacer can be appropriately selected within the scope of not damaging the purpose of the present application. For example, the width (line width) of the spacer can be in the range of 10 μm to 500 μm or in the range of 10 μm to 50 μm. The spacing (pitch) of the spacer can be in the range of 10 μm to 1000 μm or in the range of 100 μm to 1000 μm. Relative to 100% of the total area of the second base layer, the area of the spacer can be about 5% or more, and can be 50% or less. When the area of the spacer is within the above range, it can be beneficial to ensure excellent electro-optical properties while fully ensuring the adhesion between the upper substrate and the lower substrate. The range of the thickness of the spacer can be, for example, 1 μm to 30 μm or 3 μm to 20 μm.

[0082] The optical device may include at least one or more intermediate layers positioned between the first outer substrate and the liquid crystal cell, and may include at least one or more intermediate layers positioned between the second outer substrate and the liquid crystal cell. Thus, the optical device may include at least two intermediate layers. One side of each of the first outer substrate and the second outer substrate may contact an adjacent intermediate layer. Both sides of the liquid crystal cell may contact adjacent intermediate layers, respectively.

[0083] The number of intermediate layers of the optical device can be determined according to whether the optical device includes other elements in addition to the first outer substrate, the second outer substrate, and the liquid crystal element. Other elements can be exemplified by polarizers and the like.

[0084] In one example, the optical device may further include other elements, such as a polarizer, between the first outer substrate and the second outer substrate in addition to the liquid crystal cell. In this case, as an embodiment, the optical device may have a structure in which the first outer substrate, an intermediate layer, a liquid crystal cell, an intermediate layer, a polarizer, an intermediate layer, and the second outer substrate are laminated in this order. In another embodiment, the optical device may have a structure in which the first outer substrate, an intermediate layer, a polarizer, an intermediate layer, a liquid crystal cell, an intermediate layer, and the second outer substrate are laminated in this order. As another example, the optical device may have a structure in which the first outer substrate, an intermediate layer, a polarizer, an intermediate layer, a liquid crystal cell, an intermediate layer, a polarizer, an intermediate layer, and the second outer substrate are laminated in this order.

[0085] In another example, the optical device may not include other elements, such as a polarizer, between the first outer substrate and the second outer substrate in addition to the liquid crystal element. In this case, the optical device may have a structure in which the first outer substrate, the intermediate layer, the liquid crystal element, the intermediate layer, and the second outer substrate are laminated in this order.

[0086] To overcome the physical limitations of a liquid crystal cell, an outer substrate can be bonded to both sides of the cell via an intermediate layer. However, due to the low modulus of the pressure-sensitive adhesive layer, it is susceptible to external pressure, which can cause defects such as cell gap collapse or liquid crystal flow or aggregation. Controlling the thickness of the intermediate layer included in the optical device can minimize defects and ensure the structural stability and quality uniformity of the optical device.

[0087] As an example, the total thickness of the at least one or more intermediate layers may be 800 μm or greater. The total thickness of the at least one or more intermediate layers refers to the total thickness of all intermediate layers present between the first outer substrate and the liquid crystal cell, and between the second outer substrate and the liquid crystal cell. When the total thickness of the intermediate layers is within the above range, the structural stability and uniform appearance of the optical device can be ensured by minimizing defects during the lamination process of the outer substrates. Specifically, the sum of the total thickness of at least one or more intermediate layers may be 900 μm or greater, 1,000 μm or greater, 1,100 μm or greater, 1200 μm or greater, 1,300 μm or greater, 1,400 μm or greater, 1,500 μm or greater, 1,600 μm or greater, about 1,650 μm or greater, 1,700 μm or greater, 1,750 μm or greater, 1,800 μm or greater, 1,850 μm or greater, 1,900 μm or greater, 1,950 μm or greater, 2,000 μm or greater, 2,100 μm or greater, 2,150 μm or greater, or about 2,200 μm or greater. The total thickness of the at least one or more intermediate layers may be, for example, about 6,000 μm or less, 5,900 μm or less, 5,800 μm or less, 5,700 μm or less, 5,600 μm or less, 5,500 μm or less, 5,400 μm or less, 5,300 μm or less, 5,200 μm or less, 5,100 μm or less, or about 5,000 μm or less. If the total thickness of the at least one or more intermediate layers is too thick, the electro-optical characteristics of the optical device, such as transmittance characteristics, may deteriorate, so that it may be advantageous to have the thickness within the above range.

[0088] At least one or more intermediate layers may each have a single-layer structure, or may be a laminate of two or more sub-intermediate layers. The thickness and number of the sub-intermediate layers may be controlled based on the desired thickness of the intermediate layer. In one example, the thickness of the sub-intermediate layer may be in the range of 100 μm to 500 μm, or in the range of 300 μm to 400 μm.

[0089] As an example, the total thickness (Ta) of at least one or more intermediate layers positioned between the first outer substrate and the liquid crystal element and the total thickness (Tb) of at least one or more intermediate layers positioned between the second outer substrate and the liquid crystal element may be each about 400 μm or more, 500 μm or more, 600 μm or more, 700 μm or more, 800 μm or more, 900 μm or more, 1,000 μm or more, or 1,100 μm or more, and may be about 3,000 μm or less, 2,900 μm or less, 2,800 μm or less, 2,700 μm or less, about 2,600 μm or less, about 2,500 μm or less, about 2,400 μm or less, or about 2,300 μm or less. When the thicknesses Ta and Tb are within the above ranges, without compromising the electro-optical characteristics of the optical device, it is possible to ensure structural stability and uniform appearance characteristics without defects during the lamination process of the outer substrates. The sum of the total thickness (Ta) of at least one or more intermediate layers positioned between the first outer substrate and the liquid crystal cell means the sum of the thicknesses of all intermediate layers present between the first outer substrate and the liquid crystal cell. In addition, the sum of the total thickness (Tb) of at least one intermediate layer positioned between the second outer substrate and the liquid crystal cell means the sum of the thicknesses of all intermediate layers present between the second outer substrate and the liquid crystal cell.

[0090] As an example, the thickness ratio (Ta / Tb) of the total thickness (Ta) of at least one or more intermediate layers 200a positioned between the first outer substrate 100a and the liquid crystal element 300 relative to the total thickness (Tb) of at least one or more intermediate layers 200b positioned between the second outer substrate 100b and the liquid crystal element 300 may be in the range of 0.1 to 10. As another example, the thickness ratio (Ta / Tb) may be about 0.12 or greater, about 0.13 or greater, or about 0.14 or greater, and may be about 9.5 or less, 9.0 or less, 8.5 or less, 8.0 or less, 7.5 or less, or about 7.0 or less. When the thickness ratio is in the range of 0.1 to 10, the appearance defects of the liquid crystal element can be more effectively improved.

[0091] As an example, the storage elastic modulus of at least one or more intermediate layers may each be 1 MPa or greater. When the storage elastic modulus of the intermediate layer is low, the liquid crystal element may also be damaged because the base layer cannot withstand the stress of contraction and expansion in a high temperature durability test or a cycle test, etc. The storage elastic modulus of the intermediate layer may be 2 MPa or greater, or 4 MPa or greater, and may be 100 MPa or less, 80 MPa or less, 60 MPa or less, 40 MPa or less, 20 MPa or less, 10 MPa or less, or 5 MPa or less. The storage elastic modulus may be a value measured at a temperature of 25°C and a frequency of 6 radians / second.

[0092] As an example, at least one or more intermediate layers can each have a Young's modulus (E) in the range of 0.1MPa to 100MPa. As another example, the Young's modulus (E) of the intermediate layer can be about 0.2MPa or greater, 0.4MPa or greater, 0.6MPa or greater, 0.8MPa or greater, 1MPa or greater, 5MPa or greater, or about 10MPa or greater, and can be about 95MPa or less, 80MPa or less, 75MPa or less, 70MPa or less, 65MPa or less, 60MPa or less, 55MPa or less, or about 50MPa or less. Young's modulus (E) can be measured in the manner specified in ASTM D882, and can be measured using a device that can cut the film in the form provided by the relevant standards and measure stress-strain curve (force and length can be measured simultaneously), such as a UTM (universal testing machine). When the Young's modulus of the intermediate layer included in the optical device is within the above range, it can be more conducive to ensuring excellent durability of the optical device. When the intermediate layer is a laminate of at least two or more sub-intermediate layers, each of the sub-intermediate layers can meet the above Young's modulus range.

[0093] As an example, at least one or more intermediate layers may each have a coefficient of thermal expansion of 2,000 ppm / K or less. In another example, the coefficient of thermal expansion may be about 1,900 ppm / K or less, 1,700 ppm / K or less, 1,600 ppm / K or less, or about 1.500 ppm / K or less, or may be about 10 ppm / K or more, 20 ppm / K or more, 30 ppm / K or more, 40 ppm / K or more, 50 ppm / K or more, 60 ppm / K or more, 70 ppm / K or more, 80 ppm / K or more, 90 ppm / K or more, 100 ppm / K or more, 200 ppm / K or more, 300 ppm / K or more, 400 ppm / K or more, 500 ppm / K or more, 60 ppm / K or more, 700 ppm / K or more, or about 800 ppm / K or more. The coefficient of thermal expansion of the interlayer can be measured, for example, in accordance with ASTM D696. The coefficient of thermal expansion can be calculated by cutting the interlayer in the form specified in the relevant standard and measuring the change in length per unit temperature. It can also be measured using known methods such as TMA (thermomechanical analysis). When the coefficient of thermal expansion of the interlayer included in the optical device is within the above-mentioned range, it can be more conducive to ensuring excellent durability of the optical device. When the interlayer is a laminate of at least two or more sub-interlayers, each of the sub-interlayers can meet the range of the coefficient of thermal expansion.

[0094] At least one or more intermediate layers may each be a thermoplastic polyurethane (TPU) adhesive layer, a polyamide adhesive layer, a polyester adhesive layer, an EVA (ethylene vinyl acetate) adhesive layer, an acrylic adhesive layer, a silicone adhesive layer or a polyolefin adhesive layer. According to one example of the present application, at least one or more intermediate layers may each be a thermoplastic polyurethane.

[0095] The optical device may further include an outer layer surrounding the side of the liquid crystal cell. In the optical device, the top area of the liquid crystal cell may be smaller than the top area of the first outer substrate or the second outer substrate. In addition, the top area of the liquid crystal cell may be smaller than the top area of at least one or more intermediate layers included in the optical device. In one example, the liquid crystal cell may be encapsulated by an intermediate layer positioned between the first outer substrate and the liquid crystal cell, an intermediate layer positioned between the second outer substrate and the liquid crystal cell, and an outer layer. In this application, the term encapsulation may mean covering the entire surface of the liquid crystal cell with an intermediate layer and an outer layer. Depending on the desired structure, for example, the encapsulation structure can be achieved by the following method: under a vacuum state, a laminate comprising sequentially the first outer substrate, an intermediate layer, the liquid crystal cell, an intermediate layer, and the second outer substrate and comprising an outer layer surrounding the side of the liquid crystal cell is compressed. By such an encapsulation structure, the durability and weather resistance of the optical device are greatly improved, and therefore, it can be stably applied to outdoor applications such as skylights.

[0096] The outer layer may comprise, for example, a thermoplastic polyurethane (TPU) adhesive, a polyamide adhesive, a polyester adhesive, an EVA (ethylene vinyl acetate) adhesive, an acrylic adhesive, a silicone adhesive, or a polyolefin adhesive. In one example, the outer layer may be formed of the same material as the middle layer.

[0097] The present application also relates to a method for manufacturing an optical device. The optical device manufacturing method may include the following steps: preparing a laminate comprising, in sequence, a first outer substrate, at least one or more intermediate layers, a liquid crystal element, at least one or more intermediate layers, and a second outer substrate; and subjecting the laminate to a heat press treatment. Unless otherwise specified in the optical device manufacturing method, the contents described in the optical device are equally applicable.

[0098] The laminate may further include an outer layer surrounding the sides of the liquid crystal cell.

[0099] When the optical device includes other elements in addition to the liquid crystal element, such as a polarizer, the laminate may further include other elements in addition to the liquid crystal element at desired positions.

[0100] The autoclave process may be performed by heating and / or pressing the laminate formed after the lamination step.

[0101] The conditions of the autoclave process are not particularly limited, and can be performed at appropriate temperature and pressure, for example, depending on the type of interlayer being used. Typical autoclave process temperatures are approximately 80°C or higher, 90°C or higher, or 100°C or higher, and pressures are 2 atmospheres or higher, but are not limited thereto. The upper limit of the process temperature may be approximately 200°C or lower, 190°C or lower, 180°C or lower, or 170°C or lower, and the upper limit of the process pressure may be approximately 10 atmospheres or lower, 9 atmospheres or lower, 8 atmospheres or lower, 7 atmospheres or lower, or 6 atmospheres or lower.

[0102] Such an optical device can be used in various applications, and for example, can be used in eyewear such as sunglasses or AR (augmented reality) or VR (virtual reality) eyewear, building facades, or vehicle sunroofs. In one example, the optical device itself can be a vehicle sunroof. For example, in an automobile having a body with at least one opening formed therein, the optical device or vehicle sunroof attached to the opening can be installed and used.

[0103] Effects of the Invention

[0104] The optical device of the present application can ensure structural stability and good quality uniformity by properly maintaining the cell gap of the liquid crystal element, having excellent adhesion between the upper substrate and the lower substrate, and minimizing defects such as extrusion or aggregation during the lamination process of the outer substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0105] Figure 1 is a cross-sectional view of an exemplary optical device of the present application.

[0106] Figure 2 is a cross-sectional view of an exemplary liquid crystal element of the present application.

[0107] Figure 3 This is a photograph of the optical device of Comparative Example 1. DETAILED DESCRIPTION

[0108] Hereinafter, the present application will be described in detail through examples, but the scope of the present application is not limited to the following examples.

[0109] Measurement Example 1. Storage elastic modulus measurement

[0110] The storage elastic modulus was measured using TA's DMA Q800. Specifically, the storage elastic modulus value was recorded under the conditions of a temperature of 25° C., a frequency of 6 rad / s, a force of 0.01 N, and a ramp rate of 3° / min in a multi-frequency strain mode.

[0111] Example 1

[0112] Liquid crystal device manufacturing

[0113] A polycarbonate film (Keiwa) with a thickness of about 100 μm and a width × height area of 900 mm × 600 mm was prepared as the first base layer. ITO (indium tin oxide) was deposited on the first base layer to a thickness of 50 nm to form a first electrode layer. A pressure-sensitive adhesive composition (KR-3700, Shin-Etsu) was applied to the first electrode layer and then dried at about 150°C for about 5 minutes to form a pressure-sensitive adhesive layer with a thickness of about 10 μm. The storage modulus of the adhesive layer was about 0.1 MPa. The combination of the first base layer, the first electrode layer, and the pressure-sensitive adhesive layer is referred to as the upper substrate.

[0114] As the second base layer, a polycarbonate film (Keiwa) with a thickness of about 100 μm and a width × height area of 900 mm × 600 mm was prepared. On the second base layer, ITO (indium tin oxide) was deposited to a thickness of 50 nm to form a second electrode layer. An acrylic resin composition (KAD-03, Minuta Tech) was coated on the second electrode layer, and then a honeycomb-type spacer (partition wall spacer) was formed by photolithography. The spacing of the regular hexagons (closed figures) constituting the honeycomb is about 450 μm, the height is about 12 μm and the line width is about 30 μm. The area of the closed figure (regular hexagon) formed by the spacer is about 2.14 mm 2 A horizontal alignment film (Nissan, SE-7492K) was coated on the spacer to a thickness of about 300 nm and then rubbed in one direction. The combination of the second base layer, the second electrode layer, the spacer, and the horizontal alignment film is referred to as the lower substrate.

[0115] A liquid crystal composition is applied to the horizontal alignment film of the lower substrate to form a liquid crystal layer, and then a pressure-sensitive adhesive layer of the upper substrate is laminated to face the coating surface of the liquid crystal composition. The liquid crystal composition comprises a liquid crystal compound (JNC, SHN-5011XX), a chiral dopant (HCCH, S811) and a dichroic dye (LG Chem, black dye combination), wherein the content of the chiral dopant in the liquid crystal composition is 3.7% by weight, and the content of the dichroic dye is 3% by weight. The pitch (p) of the liquid crystal layer thus formed is about 2.5 μm, and the ratio (d / p) of the cell gap (d) to the pitch (p) is about 4.8. The liquid crystal cell is an HTN mode liquid crystal cell with a twist angle of 1720 degrees when no voltage is applied.

[0116] Optical device manufacturing

[0117] A laminate comprising a first outer substrate, a first intermediate layer, the prepared liquid crystal cell, a second intermediate layer, and a second outer substrate is prepared, wherein the second outer substrate is arranged in the direction of gravity compared to the first outer substrate.

[0118] As the first outer substrate, a glass substrate with a thickness of approximately 3 mm, a width x length area of 1100 mm x 800 mm, and a radius of curvature of approximately 2,470 R was used. As the second outer substrate, a glass substrate with a thickness of approximately 3 mm, a width x length area of 300 mm x 300 mm, and a radius of curvature of approximately 2,400 R was used. The first and second intermediate layers were each a laminate of two TPU layers (Argotec), one of which was approximately 380 μm thick. The TPU layer (Argotec) had a thermal expansion coefficient of 307 ppm / K and a storage elastic modulus of 2.18 MPa. The outer layer was formed from the same material as the intermediate layer.

[0119] The laminate was subjected to an autoclave process at a temperature of about 110°C and a pressure of about 2 atmospheres to produce a Figure 1 The total thickness of the intermediate layers in the optical device of Example 1 was about 1,520 μm.

[0120] Example 2

[0121] An optical device was manufactured by performing the same process as in Example 1, except that the first intermediate layer was changed to a single layer of a TPU layer (Argotec), one of which had a thickness of approximately 380 μm, and the second intermediate layer was changed to a laminate of two TPU layers (Argotec), one of which had a thickness of approximately 380 μm. The total thickness of the intermediate layers in the optical device of Example 2 was approximately 1,140 μm.

[0122] Example 3

[0123] An optical device was manufactured by performing the same process as in Example 1, except that the first intermediate layer was changed to a laminate of two TPU layers (Argotec), one of which had a thickness of approximately 380 μm, and the second intermediate layer was changed to a single TPU layer (Argotec), one of which had a thickness of approximately 380 μm. The total thickness of the intermediate layers in the optical device of Example 3 was approximately 1,140 μm.

[0124] Example 4

[0125] An optical device was manufactured by performing the same process as in Example 1, except that the first intermediate layer was changed to a laminate of two TPU layers (Argotec), one of which had a thickness of approximately 380 μm, and the second intermediate layer was changed to a laminate of three TPU layers (Argotec), one of which had a thickness of approximately 380 μm. The total thickness of the intermediate layers in the optical device of Example 4 was approximately 1,900 μm.

[0126] Example 5

[0127] An optical device was manufactured by performing the same process as in Example 1, except that the first intermediate layer was changed to a laminate of three TPU layers (Argotec), one of which had a thickness of approximately 380 μm, and the second intermediate layer was changed to a laminate of two TPU layers (Argotec), one of which had a thickness of approximately 380 μm. The total thickness of the intermediate layers in the optical device of Example 5 was approximately 1,900 μm.

[0128] Example 6

[0129] An optical device was manufactured by performing the same process as in Example 1, except that the first and second intermediate layers were each changed to a laminate of three TPU layers (Argotec), one of which had a thickness of approximately 380 μm. The total thickness of the intermediate layers in the optical device of Example 6 was approximately 2,280 μm.

[0130] Comparative Example 1

[0131] An optical device was manufactured by performing the same process as in Example 1, except that the first intermediate layer and the second intermediate layer were each changed to a single layer of TPU layer, one of which had a thickness of about 380 μm. The total thickness of the intermediate layers in the optical device of Comparative Example 1 was about 760 μm.

[0132] Evaluation Example 1. Evaluation of extrusion and accumulation defects

[0133] In the optical devices manufactured in Examples 1 to 6 and Comparative Example 1, it was observed whether squeezing and agglomeration defects occurred in a state where no voltage was applied. In Example 1, squeezing and agglomeration defects were not observed, but in Comparative Example 1, squeezing and agglomeration defects were observed, as shown in FIG. Figure 3 As shown. Figure 3 As shown in (a), the agglomerated defect area appears darker than the surrounding area because the concentration of the dichroic dye is higher than that of the surrounding area, and Figure 3 As shown in (b), the extrusion defect area appears brighter than the surrounding area because the concentration of the dichroic dye is lower than that of the surrounding area.

[0134] [Table 1]

[0135]

[0136] [Explanation of Reference Numerals]

[0137] 100a: first outer substrate, 100b; second outer substrate, 200a, 200b: intermediate layer, 300: liquid crystal element, 400: outer layer, 10a: first base layer, 10b: first electrode layer, 10c: pressure-sensitive adhesive layer, 20a: second base layer, 20b: second electrode layer, 20c: spacer, 20d: alignment film.

Claims

1. An optical device comprising: first outer base; a second outer substrate disposed opposite to the first outer substrate; a liquid crystal element positioned between the first outer substrate and the second outer substrate; as well as at least one intermediate layer positioned between the first outer substrate and the liquid crystal cell and between the second outer substrate and the liquid crystal cell, wherein The liquid crystal element includes a first base layer, a pressure-sensitive adhesive layer formed on an inner side of the first base layer, a second base layer disposed opposite to the first base layer, a spacer formed on an inner side of the second base layer, and a liquid crystal layer positioned between the first base layer and the second base layer and containing a liquid crystal compound and a dichroic dye. wherein the storage elastic modulus of the pressure-sensitive adhesive layer is in the range of 0.01 MPa to 1 MPa, wherein the storage elastic modulus of the at least one intermediate layer is each in the range of 2 MPa to 100 MPa, and The sum of the total thickness of the at least one intermediate layer is in the range of 1,100 μm to 6,000 μm. 2 . The optical device according to claim 1 , wherein the first outer substrate and the second outer substrate are each a glass substrate. 3 . The optical device according to claim 1 , wherein the optical device does not include polarizers between the first outer substrate and the liquid crystal element and between the second outer substrate and the liquid crystal element. 4 . The optical device according to claim 1 , wherein the optical device further comprises a polarizer in at least one position between the first outer substrate and the liquid crystal element and between the second outer substrate and the liquid crystal element. 5 . The optical device according to claim 1 , wherein the liquid crystal layer is switched between a first alignment state and a second alignment state different from the first alignment state by application of external energy. 6 . The optical device according to claim 1 , wherein a content of the dichroic dye in the liquid crystal layer is in a range of 0.2 wt % to 10 wt %. 7 . The optical device according to claim 1 , wherein the spacer is a patterned spacer that maintains a gap between the first base layer and the second base layer. 8 . The optical device according to claim 1 , wherein a ratio B / A of an area B of the spacer to an area A of the second base layer is in a range of 5% to 50%.

9. An optical device according to claim 1, wherein the liquid crystal element further comprises a first electrode layer formed on the inner surface of the first base layer and a second electrode layer formed on the inner surface of the second base layer, wherein the pressure-sensitive adhesive layer is present on the inner surface of the first electrode layer, and the spacer is present on the inner surface of the second electrode layer. 10 . The optical device according to claim 9 , wherein the liquid crystal element further includes an alignment film present on an inner surface of the second electrode layer, wherein no alignment film is included on an inner surface of the first foundation layer. The optical device according to claim 1 , wherein the Young's modulus of the at least one intermediate layer is each in the range of 0.1 MPa to 100 MPa. 12 . The optical device according to claim 1 , wherein a coefficient of thermal expansion of each of the at least one intermediate layer is 2,000 ppm / K or less.

13. The optical device of claim 1, wherein each of the at least one intermediate layers is a thermoplastic polyurethane adhesive layer, a polyamide adhesive layer, a polyester adhesive layer, an ethylene vinyl acetate adhesive layer, an acrylic adhesive layer, a silicone adhesive layer, or a polyolefin adhesive layer.

14. An automobile, comprising: a vehicle body having one or more openings formed therein; and the optical device according to claim 1 mounted in the opening.

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