Optical Devices

Abstract

The present application relates to an optical device, in which the cell gap of a liquid crystal cell is properly maintained, the upper and lower substrates have excellent adhesion, and the optical device can be pressed after a high-temperature and high-pressure autoclave process to prevent black spots.

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. 10-2022-0018465 dated February 11, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference. [Background technology]

[0003] For the long-term stability and large-area scalability of a liquid crystal film cell using a flexible substrate, it is important to maintain a cell gap between the upper and lower substrates and to provide adhesive strength 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 in which a pillar- or wall-shaped organic film pattern is formed on one substrate at the cell gap height and then attached to the opposite substrate using an adhesive. However, this technique requires the adhesive to be positioned only on the pillar or wall surfaces, and the technique of micro-stamping the adhesive onto the pillar or wall surfaces is difficult to process, making it difficult to control the thickness and area of ​​the adhesive. Furthermore, there is a high possibility that the adhesive will leak out when the upper and lower substrates are bonded, which could contaminate the alignment film or liquid crystal. Summary of the Invention [Problem to be solved by the invention]

[0005] To maintain the cell gap of the liquid crystal cell and ensure adhesion between the upper and lower substrates, it is possible to consider forming a spacer and an alignment film on the lower substrate, and then forming an adhesive layer with liquid crystal alignment and adhesive properties on the upper substrate before bonding. However, when the liquid crystal cell is subjected to an autoclave process that bonds the substrates at high temperature and pressure, there is a problem of black spots appearing due to pressing. The objective of this application is to provide an optical device that properly maintains the cell gap of the liquid crystal cell, has excellent adhesion between the upper and lower substrates, and does not exhibit black spots due to pressing even after an autoclave process at high temperature and pressure. [Means for solving the problem]

[0006] This application relates to an optical device. The optical device may include a liquid crystal cell. FIG. 1 exemplarily illustrates the structure of the liquid crystal cell. The liquid crystal cell may include an upper substrate, a lower substrate, and a liquid crystal layer containing a liquid crystal compound between the upper and lower substrates. The upper substrate may include a first base layer 10a and a first adhesive layer 10c. The upper substrate may further include a first electrode layer 10b between the first base layer 10a and the adhesive layer 10c. The lower substrate may include a second base layer 20a and a spacer 20c. The lower substrate may further include a second electrode layer 20b between the second base layer 20a and the spacer 20c. The lower substrate may also include an alignment layer 20d on the spacer 20c. A liquid crystal layer 30 filled with a liquid crystal compound may exist in the space between the upper and lower substrates.

[0007] The first and second substrate layers may be made of, for example, a glass film, a crystalline or amorphous silicone film, an inorganic film such as quartz or an ITO (Indium Tin Oxide) film, or a polymer film.

[0008] In one example, the first substrate layer and the second substrate layer may each be a polymer film to realize a flexible device. Examples of polymer films that can be used include, but are not limited to, triacetyl cellulose (TAC); cycloolefin copolymer (COP) such as norbornene derivatives; poly(methyl methacrylate) (PMMA); polycarbonate (PC); polyethylene (PE); polypropylene (PP); polyvinyl alcohol (PVA); diacetyl cellulose (DAC); polyacrylate (PAC); polyether sulfone (PES); polyetheretherketon (PEEK); polyphenylsulfone (PPS), polyetherimide (PEI); polyethylene maphthlate (PEN); polyethyleneterephtalate (PET); polyimide (PI); polysulfone (PSF); polyarylate (PAR), and amorphous fluororesin. The first substrate layer and the second substrate layer may optionally have a coating layer such as gold, silver, or a silicon compound such as silicon dioxide or silicon monoxide, or an anti-reflection layer.

[0009] In one example, optically anisotropic films may be used as the first and second substrate layers. Such optically anisotropic films typically have anisotropic mechanical properties, and by utilizing this anisotropy, a liquid crystal cell or optical device having superior durability can be provided.

[0010] In one example, the first substrate layer and the second substrate layer may each be a polymer film having an in-plane retardation value of 4,000 nm or more at a wavelength of 550 nm. Specifically, the in-plane retardation value may be 5,000 nm or more, 6,000 nm or more, 7,000 nm or more, 8,000 nm or more, or 9,000 nm or more, and may be 50,000 nm or less, 40,000 nm or less, 30,000 nm or less, 20,000 nm or less, 18,000 nm or less, 16,000 nm or less, 15,000 nm or less, or 12,000 nm or less. This may be advantageous for providing a liquid crystal cell free of optical defects such as rainbow phenomenon.

[0011] In this specification, the in-plane retardation is a physical quantity defined by the following mathematical formula A. [Formula A] Rin=d×(nx-ny) In Formula A, Rin is the in-plane retardation, nx is the refractive index of the film in the slow axis direction, ny is the refractive index of the film in the fast axis direction, and d is the film thickness. nx and ny represent the refractive indices of the film in the x-axis and y-axis directions, respectively. The x-axis represents the direction parallel to the in-plane slow axis of the film, and the y-axis represents the direction parallel to the in-plane fast axis of the film, and the x-axis and y-axis may be perpendicular to each other in the plane.

[0012] The specific type of film that can be used as the substrate layer is not particularly limited as long as it exhibits an in-plane retardation within the range mentioned above. For example, an anisotropic polymer film that has been given optical anisotropy by stretching can be used. Examples of polymer films include polyolefin films such as polyethylene film or polypropylene film, cycloolefin polymer (COP) films such as polynorbornene film, cellulose ester polymer films such as polyvinyl chloride film, polyacrylonitrile film, polysulfone, polyacrylate film, PVA (poly(vinyl alcohol)) film, and TAC (triacetyl cellulose) film, polyester film, polycarbonate film, and copolymer films of two or more monomers that form the polymer.

[0013] As one example, the film may be a polyester film such as a PET (poly(ethylene terephthalate)) film. Films exhibiting in-plane retardation within the above range are well known in the art, and in the case of polymer films, such films not only exhibit large optical anisotropy but also exhibit asymmetry in mechanical properties due to stretching during the manufacturing process. A representative example of such retardation films known in the art is a stretched polyester film such as a stretched PET (poly(ethylene terephthalate)) film.

[0014] When the anisotropic film is applied simultaneously to the first and second substrate layers, the substrates may be arranged so that the slow axes therebetween are parallel or perpendicular to each other.

[0015] As an example, the film may be a polyester film such as a PET film, but the type of film that can be used as the substrate in this application is not limited thereto.

[0016] In one example, the first and second substrate layers may each have a thickness of about 10 μm to about 1,000 μm. In another example, the thickness of the substrate layers may each be 20 μm or more, 40 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, 120 μm or more, or 140 μm or more, and may be 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, or about 400 μm or less. When the thicknesses of the first and second substrate layers satisfy the above ranges, this may be advantageous in reducing appearance defects such as wrinkles when bonding a liquid crystal cell to an outer substrate to manufacture an optical device.

[0017] The adhesive layer may be present on the inner surface of the first substrate layer. In this specification, the "inner surface" of a component included in the liquid crystal cell may refer to the surface facing the liquid crystal layer. The use of such an adhesive layer can provide adhesion between the upper and lower substrates to prevent separation of the liquid crystal cell during the bonding process for supporting the liquid crystal composition between the upper and lower substrates and in subsequent processes. The adhesive layer may also be advantageous for roll-to-roll processability and for preventing the liquid crystal composition from flowing.

[0018] As used herein, the adhesive layer may be, for example, a layer of an adhesive composition. As used herein, the term "adhesive composition layer" may refer to a layer formed by coating or curing an adhesive composition. The term "curing of an adhesive composition" may refer to the realization of a crosslinked structure within the adhesive composition through a physical or chemical action or reaction of components contained in the adhesive composition. Curing may be induced, for example, by maintaining at room temperature, applying moisture, applying heat, irradiating with active energy rays, or by a combination of two or more of the above processes. The types of adhesive compositions that are cured accordingly may be referred to as, for example, room-temperature-curable adhesive compositions, moisture-curable adhesive compositions, heat-curable adhesive compositions, active energy ray-curable adhesive compositions, or hybrid-curable adhesive compositions.

[0019] The pressure-sensitive adhesive layer may be optically transparent, and may have an average transmittance of about 80% or more, 85% or more, 90% or more, or 95% or more in the visible light region, for example, wavelengths of 380 nm to 780 nm.

[0020] The adhesive layer may be a liquid crystal aligning adhesive layer. The adhesive layer may be, for example, a vertically aligning adhesive layer or a horizontally aligning adhesive layer. In this specification, a "vertically aligning adhesive" may refer to an adhesive that imparts vertical alignment force to adjacent liquid crystal molecules and has adhesive strength capable of bonding an upper substrate and a lower substrate. In this specification, a "horizontally aligning adhesive" may refer to an adhesive that imparts horizontal alignment force to adjacent liquid crystal molecules and has adhesive strength capable of bonding an upper substrate and a lower substrate. The pretilt angle of the adjacent liquid crystal compound relative to the vertically aligning adhesive may be within a 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 compound relative to the horizontally aligning adhesive may be within a range of 0 to 10 degrees, 0 to 5 degrees, or 0 to 3 degrees. According to one embodiment of the present application, the adhesive layer may be a vertically aligning adhesive layer.

[0021] In this specification, the pretilt angle may refer to the angle that the director of the liquid crystal compound makes with respect to a plane horizontal to the liquid crystal alignment adhesive or alignment film when no voltage is applied. In this specification, the director of the liquid crystal compound may refer to the optical axis or slow axis of the liquid crystal layer. Alternatively, the director of the liquid crystal compound may refer to the long axis direction when the liquid crystal compound is rod-shaped, or to the axis parallel to the normal direction of the disc plane when the liquid crystal compound is discotic.

[0022] When the adhesive layer is a vertically oriented adhesive layer, the surface energy of the adhesive layer may be 16 mN / m or less. The lower limit of the surface energy may be, for example, 5 mN / m or more. When the adhesive layer is a horizontally oriented adhesive layer, the surface energy of the adhesive layer may be more than 16 mN / m. The upper limit of the surface energy may be, for example, 50 mN / m or less. The surface energy may be measured using a drop shape analyzer (DSA100 product from KRUSS). Specifically, deionized water with a known surface tension is dropped onto the surface of the adhesive, and the contact angle is measured five times. The average of the five contact angles is then calculated. Similarly, diiodomethane with a known surface tension is dropped onto the surface of the adhesive, and the contact angle is measured five times. The average of the five contact angles is then calculated. The surface energy can then be calculated by substituting the Strom value for the surface tension of the solvent using the Owens-Wendt-Rabel-Kaelble method using the average contact angles for deionized water and diiodomethane. The surface energy (γsurface) of a sample can be calculated by taking into account the dispersion force between nonpolar molecules and the interaction force between polar molecules (γsurface = γdispersion + γpolar), and the ratio of the polar term (γpolar) to the surface energy (γsurface) can be defined as the polarity of the surface.

[0023] The thickness of the adhesive layer may be, for example, within a range of 3 μm to 15 μm. When the thickness of the adhesive layer is within this range, it may be advantageous in minimizing defects such as pressure or gathering of the adhesive when used in manufacturing a liquid crystal cell while ensuring adhesion between the upper and lower substrates.

[0024] The adhesive layer may be made of various types of adhesives known in the industry as OCA (Optically Clear Adhesive), which may differ from OCR (Optically Clear Resin) type adhesives in that they cure before the objects are bonded together.

[0025] The adhesive layer may include a silicone adhesive. In the case of a silicone adhesive, the adhesive composition may include a curable silicone compound as the adhesive resin. An adhesive composition including a curable silicone compound as the adhesive resin may be referred to as a silicone composition. The silicone adhesive may include a cured product of the curable silicone compound as the adhesive resin. When a silicone adhesive is used, it may be suitable for exerting a vertical alignment force on the liquid crystal due to the difference in surface energy with the liquid crystal, and may also be advantageous in terms of preventing contamination of the liquid crystal. The type of curable silicone compound is not particularly limited, and for example, a heat-curable silicone compound or an ultraviolet-curable silicone compound may be used.

[0026] In one example, the curable silicone compound can be an addition-curable silicone compound.

[0027] Specifically, examples of the addition-curable silicone compound include, but are not limited to, (1) organopolysiloxanes containing two or more alkenyl groups in the molecule and (2) organopolysiloxanes containing two or more silicon-bonded hydrogen atoms in the molecule.

[0028] The silicone compounds described above can form cured products by addition reaction in the presence of a catalyst such as platinum.

[0029] The organopolysiloxane (1) is a main component constituting the silicone cured product and contains at least two alkenyl groups per molecule. Specific examples of the alkenyl groups include vinyl, allyl, butenyl, pentenyl, hexenyl, and heptenyl groups, among which vinyl groups are commonly used, but are not limited thereto. The bonding position of the alkenyl groups in the organopolysiloxane (1) is not particularly limited. For example, the alkenyl groups may be bonded to the ends of branched chains and / or to the side chains of branched chains. In addition to the alkenyl, the types of substituents that may be contained in the organopolysiloxane (1) include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl. Of these, methyl and phenyl groups are typically used, but the present invention is not limited thereto.

[0030] The molecular structure of the organopolysiloxane (1) is not particularly limited and may have any shape, such as linear, branched, cyclic, network, or linear with some branching, etc. Of the molecular structures described above, those having a linear molecular structure are typically used, but are not limited thereto.

[0031] More specific examples of the organopolysiloxane (1) include a dimethylsiloxane-methylvinylsiloxane copolymer having both branched chain terminals blocked with trimethylsiloxane groups, a methylvinylpolysiloxane having both branched chain terminals blocked with trimethylsiloxane groups, a dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer having both branched chain terminals blocked with trimethylsiloxane groups, a dimethylpolysiloxane having both branched chain terminals blocked with dimethylvinylsiloxane groups, a methylvinylpolysiloxane having both branched chain terminals blocked with dimethylvinylsiloxane groups, a dimethylsiloxane-methylvinylsiloxane copolymer having both branched chain terminals blocked with dimethylvinylsiloxane groups, a dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer having both branched chain terminals blocked with dimethylvinylsiloxane groups, and R 1 2SiO 2 / 2 The siloxane unit represented by R 1 2nd Round 2 SiO 1 / 2 The siloxane unit represented by SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 2nd Round 2 SiO 1 / 2 The siloxane unit represented by SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 R 2 SiO 2 / 2 The siloxane unit represented by R 1 SiO 3 / 2 Siloxane units denoted by R 2 SiO 3 / 2 Examples of suitable organopolysiloxanes include, but are not limited to, organopolysiloxane copolymers containing siloxane units represented by the formula: 1is a hydrocarbon group other than an alkenyl group, specifically 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; a halogen-substituted alkyl group such as a chloromethyl group, a 3-chloropropyl group, or a 3,3,3-trifluoropropyl group; 2 is an alkenyl group, and specifically may be a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, or the like.

[0032] In the addition-curable silicone composition, the (2) organopolysiloxane can crosslink the (1) organopolysiloxane. The bonding position of the hydrogen atoms in the (2) organopolysiloxane is not particularly limited, and for example, they may be bonded to the end of a branched chain and / or a side chain. The types of substituents that may be included in the (2) organopolysiloxane in addition to the silicon-bonded hydrogen atoms are also not particularly limited, and examples include alkyl groups, aryl groups, aralkyl groups, and halogen-substituted alkyl groups, as described for the (1) organopolysiloxane. Among these, methyl groups and phenyl groups are typically used, but are not limited thereto.

[0033] The molecular structure of the organopolysiloxane (2) is not particularly limited and may have any shape, such as linear, branched, cyclic, network, or linear with some branching, etc. Among the molecular structures described above, those having a linear molecular structure are usually used, but are not limited thereto.

[0034] More specific examples of the (2) organopolysiloxane include methylhydrogenpolysiloxanes having both branched chain terminals blocked with trimethylsiloxane groups, dimethylsiloxane-methylhydrogen copolymers having both branched chain terminals blocked with trimethylsiloxane groups, dimethylsiloxane-methylhydrogensiloxane-methylphenylsiloxane copolymers having both branched chain terminals blocked with trimethylsiloxane groups, dimethylpolysiloxanes having both branched chain terminals blocked with dimethylhydrogensiloxane groups, dimethylsiloxane-methylphenylsiloxane copolymers having both branched chain terminals blocked with dimethylhydrogensiloxane groups, methylphenylpolysiloxanes having both branched chain terminals blocked with dimethylhydrogensiloxane groups, R 1 3SiO 1 / 2 The siloxane unit represented by R 1 2HSiO 1 / 2 The siloxane unit represented by SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 2HSiO 1 / 2 The siloxane unit represented by SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 HSiO 2 / 2 The siloxane unit represented by R 1 SiO 3 / 2 Siloxane units denoted by HSiO 3 / 2 Examples of suitable organopolysiloxanes include, but are not limited to, organopolysiloxane copolymers containing siloxane units represented by the formula: 1 is a hydrocarbon group other than an alkenyl group, and specifically may be an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or a heptyl group; an 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; or a halogen-substituted alkyl group such as a chloromethyl group, a 3-chloropropyl group, or a 3,3,3-trifluoropropyl group.

[0035] The content of the (2) organopolysiloxane is not particularly limited as long as it is present in an amount that allows for appropriate curing. For example, the (2) organopolysiloxane may be present in an amount such that the number of silicon-bonded hydrogen atoms is 0.5 to 10 per alkenyl group contained in the (1) organopolysiloxane. Within this range, curing can proceed sufficiently, ensuring heat resistance.

[0036] The addition-curable silicone composition may further contain appropriate additives in appropriate proportions required to improve storage stability, handling, and workability.

[0037] In another example, the silicone composition is a condensation-curable silicone composition, and can include, for example, (a) an alkoxy group-containing siloxane polymer; and (b) a hydroxyl group-containing siloxane polymer.

[0038] The (a) siloxane polymer may be, for example, a compound represented by the following chemical formula I: [Chemical formula I] R 1 a R 2 b SiO c (OR 3 ) d R in Chemical Formula I 1 and R 2 each independently represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, and R 3 represents an alkyl group, and R 1 , R 2 and R 3 When there are multiple of each, they may be the same or different, a and b each independently represent a number greater than or equal to 0 and less than 1, a+b represents a number greater than 0 and less than 2, c represents a number greater than 0 and less than 2, d represents a number greater than 0 and less than 4, and a+b+c×2+d is 4.

[0039] In the definition of Chemical Formula I, the monovalent hydrocarbon may be, for example, an alkyl group having 1 to 8 carbon atoms, a phenyl group, a benzyl group, or a tolyl group, and in this case, the alkyl group having 1 to 8 carbon atoms may be, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, or an octyl group. In addition, in the definition of Chemical Formula 1, the monovalent hydrocarbon group may be substituted with a known substituent such as a halogen, an amino group, a mercapto group, an isocyanate group, a glycidyl group, a glycidoxy group, or a ureido group.

[0040] In the definition of Formula I, R 3 Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. Among the alkyl groups, a methyl group or an ethyl group is usually used, but is not limited thereto.

[0041] A branched or tertiary crosslinked siloxane polymer can be used among the polymers of Chemical Formula I. Furthermore, this (a) siloxane polymer may contain residual hydroxyl groups to the extent that it does not impair the intended purpose, specifically, to the extent that it does not inhibit the dealcoholization reaction.

[0042] The (a) siloxane polymer can be produced, for example, by hydrolysis and condensation of a polyfunctional alkoxysilane or a polyfunctional chlorosilane. A skilled artisan can easily select an appropriate polyfunctional alkoxysilane or chlorosilane for the desired (a) siloxane polymer, and can easily control the conditions for the hydrolysis and condensation reaction using the selected alkoxysilane. Meanwhile, when producing the (a) siloxane polymer, an appropriate monofunctional alkoxysilane may be used in combination depending on the purpose.

[0043] As the (a) siloxane polymer, for example, commercially available organosiloxane polymers such as X40-9220 or X40-9225 from Shin-Etsu Silicones, and XR31-B1410, XR31-B0270 or XR31-B2733 from GE Toray Silicones can be used.

[0044] As the hydroxyl group-containing siloxane polymer (b) contained in the condensation-curable silicone composition, for example, a compound represented by the following chemical formula II can be used. [Chemical formula II] [ka] In Formula II, R 4 and R 5 each independently represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; R 4 and R 5 When there are a plurality of each of them, they may be the same or different, and n represents an integer of 5 to 2,000.

[0045] In the definition of chemical formula II, specific types of monovalent hydrocarbon groups include, for example, the same hydrocarbon groups as those in the case of chemical formula I above.

[0046] The (b) siloxane polymer can be produced, for example, by hydrolysis and condensation of dialkoxysilane and / or dichlorosilane. A person skilled in the art can easily select an appropriate dialkoxysilane or dichlorosilane for the desired (b) siloxane polymer, and can easily control the conditions for the hydrolysis and condensation reaction using the dialkoxysilane or dichlorosilane. As the (b) siloxane polymer, commercially available bifunctional organosiloxane polymers such as XC96-723, YF-3800, and YF-3804 from GE Toray Silicone Co., Ltd. can be used.

[0047] According to the present application, controlling the storage modulus and tangent delta value of the adhesive layer at 110°C can prevent black spots after high-temperature and high-pressure autoclaving. In this specification, tangent delta (tanδ) is expressed as G" / G' (G' is the storage modulus and G" is the loss modulus). The storage modulus (G') refers to the elasticity of the adhesive, and the loss modulus (G") refers to the viscosity of the adhesive. A higher storage modulus indicates a harder and more elastic adhesive, while a higher loss modulus indicates a softer and more viscous adhesive. Since adhesives possess both elasticity and viscosity, they can be expressed by the loss factor tanδ, which is the ratio of the loss modulus to the storage modulus. A tanδ value less than 1 indicates a high elasticity, and a value greater than 1 indicates a high viscosity.

[0048] In one example, the storage modulus of the pressure-sensitive adhesive layer at a temperature of 110°C and a frequency of 1 rad / sec may be 18,000 Pa or more. The storage modulus of the pressure-sensitive adhesive layer at a temperature of 110°C and a frequency of 1 rad / sec may be 100,000 Pa or less. Specifically, the storage modulus of the pressure-sensitive adhesive layer may be 19,000 Pa or more, 19,500 Pa or more, 20,000 Pa or more, 20,500 Pa or more, 21,000 Pa or more, 21,500 Pa or more, 22,000 Pa or more, 22,500 Pa or more, 23,000 Pa or more, 23,500 Pa or more, 24,000 Pa or more, 24,500 Pa or more, 25,000 Pa or more, 30,000 Pa or more, 35,000 Pa or more, 40,000 Pa or more, 45,000 Pa or more, or 50,000 Pa or more, and more preferably 90,000 Pa or more. The storage modulus of the pressure-sensitive adhesive layer at a temperature of 110°C and a frequency of 1 rad / sec can be 25,000 Pa or less, 85,000 Pa or less, 80,000 Pa or less, 75,000 Pa or less, 70,000 Pa or less, 65,500 Pa or less, 60,000 Pa or less, 55,000 Pa or less, 50,000 Pa or less, 45,500 Pa or less, 40,000 Pa or less, 35,500 Pa or less, 30,000 Pa or less, 25,000 Pa or less, 25,500 Pa or less, 24,000 Pa or less, 23,500 Pa or less, 23,000 Pa or less, 22,000 Pa or less, 21,000 Pa or less, or 20,000 Pa or less. When the storage modulus of the pressure-sensitive adhesive layer at a temperature of 110°C and a frequency of 1 rad / sec is within the above range, black spots can be prevented after high-temperature and high-pressure autoclaving.

[0049] In one example, the pressure-sensitive adhesive layer may have a storage modulus of 10,000 Pa or more at a temperature of 25° C. and a frequency of 1 rad / sec. The pressure-sensitive adhesive layer may have a storage modulus of 1,100,000 Pa or less at a temperature of 25° C. and a frequency of 1 rad / sec. The storage modulus of the pressure-sensitive adhesive layer may be specifically 30,000 Pa or more, 35,000 Pa or more, 50,000 Pa or more, 100,000 Pa or more, 150,000 Pa or more, 200,000 Pa or more, 250,000 Pa or more, 300,000 Pa or more, 350,000 Pa or more, 400,000 Pa or more, 500,000 Pa or more, 600,000 Pa or more, 700,000 Pa or more, 800,000 Pa or more, or 900,000 Pa or more. The storage modulus may be 900,000 Pa or less, 800,000 Pa or less, 700,000 Pa or less, 600,000 Pa or less, 500,000 Pa or less, 450,000 Pa or less, 400,000 Pa or less, 350,000 Pa or less, 300,000 Pa or less, 250,000 Pa or less, 200,000 Pa or less, 150,000 Pa or less, 100,000 Pa or less, or 50,000 Pa or less. When the storage modulus of the adhesive layer at a temperature of 25°C and a frequency of 1 rad / sec is within the above range, it can be advantageous to ensure excellent electro-optical properties and appearance uniformity by minimizing defects such as pressure-sensitive adhesive squeezing and gathering during the manufacture of liquid crystal cells while ensuring adhesion between the upper and lower substrates.

[0050] In one example, the tangent delta value of the PSA layer at a temperature of 110°C and a frequency of 1 rad / sec may be 0.32 or less. The tangent delta value of the PSA layer at a temperature of 110°C and a frequency of 1 rad / sec may be 0.1 or more. Specifically, the tangent delta value of the PSA layer may be 0.31 or less, 0.30 or less, 0.29 or less, 0.28 or less, 0.27 or less, 0.26 or less, 0.25 or less, 0.24 or less, 0.23 or less, or 0.22 or less, or 0.12 or more, 0.14 or more, 0.16 or more, 0.18 or more, 0.20 or more, 0.22 or more, 0.24 or more, 0.26 or more, 0.28 or more, or 0.30 or more. When the tangent delta value of the PSA layer at a temperature of 110°C and a frequency of 1 rad / sec is within the above range, black spots can be prevented after high-temperature and high-pressure autoclaving.

[0051] In one example, the pressure-sensitive adhesive layer may have a tangent delta value of 2.0 or less at a frequency of 1 rad / sec at a temperature of 25° C. The pressure-sensitive adhesive layer may have a tangent delta value of 0.1 or more at a frequency of 1 rad / sec at a temperature of 25° C. Specifically, the tangent delta value of the pressure-sensitive adhesive layer may be 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, or 1.5 or more, and may be 2.0 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, or 0.45 or less. When the tangent delta value of the adhesive layer at a temperature of 25°C and a frequency of 1 rad / sec is within the above range, it can be advantageous to ensure excellent electro-optical properties and appearance uniformity by ensuring adhesion between the upper and lower substrates and minimizing defects such as pressure and gathering of the adhesive during the manufacturing of the liquid crystal cell.

[0052] Methods for controlling the storage modulus and tangent delta value of a pressure-sensitive adhesive layer are known, and the method for controlling the storage modulus and tangent delta value in this application is not particularly limited. As an example, the storage modulus and tangent delta value of a pressure-sensitive adhesive layer can be controlled by appropriately adjusting the catalyst and crosslinker of the pressure-sensitive adhesive and / or pressure-sensitive adhesive composition and the curing conditions of the pressure-sensitive adhesive. The following are merely exemplary conditions for providing the pressure-sensitive adhesive of this application, and the scope of this application is not limited thereto.

[0053] In one example, the adhesive and / or adhesive composition may further include a catalyst for curing. For example, a platinum-based catalyst may be used as the catalyst. The amount of the catalyst may be adjusted depending on the desired physical properties of the adhesive layer. The catalyst may be included in an amount of 0.1 parts by weight or more, 0.5 parts by weight or more, or 1 part by weight or more, or 1.5 parts by weight or less, 1.3 parts by weight or less, or 1.1 parts by weight or less, per 100 parts by weight of the adhesive resin.

[0054] According to the examples of the present application, when all other conditions are the same except for the catalyst content, the higher the catalyst content, the lower the storage modulus and the lower the tangent delta value.

[0055] In one embodiment, the adhesive and / or adhesive composition may further include a crosslinker. The crosslinker may be, for example, a silane compound. The silane compound may be, for example, a compound represented by Chemical Formula 1 or Chemical Formula 2. The crosslinker may be included in an amount of 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, 4 parts by weight or more, 5 parts by weight or more, 7 parts by weight or more, 10 parts by weight or more, 12 parts by weight or more, or 15 parts by weight or more, relative to 100 parts by weight of the adhesive resin, and may be included in an amount of 20 parts by weight or less, 19 parts by weight or less, 18 parts by weight or less, 17 parts by weight or less, 16 parts by weight or less, 15 parts by weight or less, 13 parts by weight or less, 11 parts by weight or less, 9 parts by weight or less, 7 parts by weight or less, 5 parts by weight or less, or 3 parts by weight or less. [Chemical formula 1] [ka] In Chemical Formula 1, R1 to R8 may each independently be an alkyl group having 1 to 4 carbon atoms. Specifically, in Chemical Formula 1, R1 to R8 may each independently be an alkyl group having 1 to 3 carbon atoms or an alkyl group having 1 to 2 carbon atoms. According to one embodiment of the present application, R1 to R8 may each be a methyl group. [Chemical formula 2] [ka] In Chemical Formula 2, R1 is an alkyl group having 10 to 30 carbon atoms, and R2 to R4 are each independently an alkyl group having 1 to 4 carbon atoms. In Chemical Formula 2, R1 may specifically be an alkyl group having 10 or more, 12 or more, 14 or more, 16 or more, or 18 or more carbon atoms. In Chemical Formula 2, R1 may specifically be an alkyl group having 30 or less, 28 or less, 26 or less, 24 or less, 22 or less, 20 or less, or 18 or less carbon atoms. The alkyl group may be a linear alkyl group. In Chemical Formula 2, R2 to R4 may each independently be an alkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 3 carbon atoms, or an alkyl group having 1 to 2 carbon atoms. According to one embodiment of the present application, R2 to R4 may each be a methyl group.

[0056] In one example, the curing temperature for providing the adhesive layer may be, for example, within a range of about 140°C to 180°C. The curing time for providing the adhesive may be, for example, 3 minutes to 15 minutes. Specifically, the adhesive layer may be provided by coating the adhesive composition on a release film and then curing it under the above conditions. According to the examples of the present application, when all other conditions except the curing time are the same, the longer the curing time, the higher the storage modulus and the lower the tangent delta value. According to the examples of the present application, when all other conditions except the curing temperature are the same, the higher the curing temperature, the higher the storage modulus and the lower the tangent delta value.

[0057] The upper and lower substrates of the liquid crystal cell may be attached to each other by an adhesive layer. Specifically, the adhesive layer of the upper substrate may be attached to the spacers of the lower substrate. When an alignment film is formed on the spacers of the lower substrate, the areas of the alignment film corresponding to the spacers may be attached to the adhesive layer of the upper substrate.

[0058] Liquid crystal compounds can switch their alignment state by applying a voltage. Liquid crystal compounds whose alignment direction can be changed by applying an external force can be used. As used herein, the term "external force" refers to any external factor, such as an external voltage, that can affect the behavior of a substance contained in a liquid crystal layer. Therefore, a state without an external force can refer to a state in which no external voltage or the like is applied.

[0059] The type and properties of the liquid crystal compound may be appropriately selected taking into consideration the purpose of the present application. For example, the liquid crystal compound may be a nematic liquid crystal or a smectic liquid crystal. Nematic liquid crystal may refer to a liquid crystal in which rod-shaped liquid crystal molecules are aligned parallel to the long axis direction of the liquid crystal molecules without any regularity in terms of their positions, while smectic liquid crystal may refer to a liquid crystal in which rod-shaped liquid crystal molecules are regularly arranged to form a layered structure and are aligned parallel to the long axis direction with regularity. According to one embodiment of the present application, the liquid crystal compound may be a nematic liquid crystal compound.

[0060] The nematic liquid crystal compound may be selected to have a clearing point of, for example, about 40° C. or higher, 50° C. or higher, 60° C. or higher, 70° C. or higher, 80° C. or higher, 90° C. or higher, 100° C. or higher, or about 110° C. or higher, or 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, 150° C. or lower, or about 140° C. or lower.

[0061] The liquid crystal compound may be a non-reactive liquid crystal compound. The non-reactive liquid crystal compound may refer to a liquid crystal compound that does not have a polymerizable group. Examples of the polymerizable group include, but are not limited to, an acryloyl group, an acryloyloxy group, a methacryloyl group, a methacryloyloxy group, a carboxy group, a hydroxy group, a vinyl group, and an epoxy group. The polymerizable group may include known functional groups known as polymerizable groups.

[0062] The dielectric anisotropy of a liquid crystal compound may be positive or negative. The absolute value of the dielectric anisotropy of a liquid crystal compound may be appropriately selected taking into account the objectives of this application. The term "dielectric anisotropy (Δε)" may refer to the difference (ε / / -ε⊥) between the horizontal dielectric constant (ε / / ) and the vertical dielectric constant (ε⊥) of a liquid crystal. As used herein, the term "horizontal dielectric constant (ε / / )" refers to the dielectric constant measured along the direction of an electric field when a voltage is applied such that the direction of the electric field is substantially horizontal to the director of the liquid crystal compound, and the term "vertical dielectric constant (ε⊥)" refers to the dielectric constant measured along the direction of the electric field when a voltage is applied such that the direction of the electric field is substantially perpendicular to the director of the liquid crystal compound. The dielectric anisotropy of liquid crystal molecules may be in the range of 5 to 25.

[0063] The refractive index anisotropy (Δn) of a liquid crystal compound can be appropriately selected taking into consideration the purpose of the present application. In this specification, the term "refractive index anisotropy" refers to the extraordinary refractive index (n e ) and ordinary refractive index (n o ) difference (n e -n o The refractive index anisotropy of the liquid crystal compound may be, for example, 0.01 to 0.3. The refractive index anisotropy may be 0.01 or more, 0.05 or more, or 0.07 or more, and may be 0.3 or less, 0.2 or less, 0.15 or less, or 0.13 or less.

[0064] The liquid crystal layer may further include a dichroic dye. The dichroic dye can control the light transmittance variable characteristics of the liquid crystal layer. As used herein, the term "dye" may refer to a substance capable of intensively absorbing and / or transforming light within at least a portion or all of the visible light range, e.g., a wavelength range of 400 nm to 700 nm, and the term "dichroic dye" may refer to a substance capable of anisotropic absorption of light within at least a portion or all of the visible light range.

[0065] A liquid crystal layer containing a liquid crystal compound and a dichroic dye may be a GHLC (guest-host liquid crystal layer). In this specification, the term "GHLC (guest-host liquid crystal layer)" refers to a functional layer in which the dichroic dye is aligned with the alignment of the liquid crystal compound, exhibiting anisotropic light absorption characteristics in both the alignment direction of the dichroic dye and the direction perpendicular to the alignment direction. For example, a dichroic dye is a material whose light absorption rate varies depending on the polarization direction. If it has a high absorption rate for light polarized along its long axis, it is called a p-type dye, and if it has a high absorption rate for light polarized along its short axis, it is called an n-type dye. For example, when a p-type dye is used, polarized light vibrating along the long axis of the dye is absorbed, while polarized light vibrating along the short axis of the dye is transmitted due to low absorption. Hereinafter, unless otherwise specified, the dichroic dye is assumed to be a p-type dye.

[0066] As the dichroic dye, for example, a known dye that is known to have the property of being able to align according to the alignment state of the liquid crystal compound due to 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, quaterrylene dyes, benzothiadiazole dyes, diketopyrrolopyrrole dyes, squaraine dyes, and pyrromethene dyes, but the dyes applicable in the present application are not limited to these.

[0067] The dichroic dye may have a dichroic ratio, i.e., the ratio of the absorption of light polarized parallel to the long axis of the dichroic dye divided by the absorption of light polarized perpendicular to the long axis, of 5 or more, 6 or more, or 7 or more. The dye may satisfy the dichroic ratio at at least some wavelengths or any one wavelength within the wavelength range of the visible light region, for example, about 380 nm to 700 nm or about 400 nm to 700 nm. The upper limit of the dichroic ratio may be, for example, about 20 or less, 18 or less, 16 or less, or 14 or less.

[0068] The content of the dichroic dye in the liquid crystal layer may be appropriately selected taking into account the objectives of the present application. For example, the content of the dichroic dye in the liquid crystal layer may be 0.2 wt % or more. Specifically, the content of the dichroic dye may be 0.5 wt % or more, 1 wt % or more, 2 wt % or more, or 3 wt % or more. The upper limit of the content of the dichroic dye may be, for example, 10 wt % or less, 9 wt % or less, 8 wt % or less, 6 wt % or less, or 5 wt % or less. If the content of the dichroic dye in the liquid crystal layer is too low, it may be difficult to achieve the desired transmittance variable characteristics, and if the content of the dichroic dye in the liquid crystal layer is too high, precipitation may occur. Therefore, it is advantageous for the content of the dichroic dye to be within the above range.

[0069] The thickness of the liquid crystal layer is not particularly limited, and may be, for example, about 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.5 μm or more, 1 μm or more, 1.5 μm or more, 2 μm or more, 2.5 μm or more, 3 μm or more, 3.5 μm or more, 4 μm or more, 4.5 μm or more, 5 μm or more, 5.5 μm or more, 6 μm or more, 6.5 μm or more, 7 μm or more, 7.5 μm or more, 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 may generally be about 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0070] The liquid crystal cell can switch the alignment state of the liquid crystal layer depending on the applied voltage. In one example, when no voltage is applied to the liquid crystal cell, the liquid crystal layer can have a first alignment state, and when a voltage is applied to the liquid crystal cell, the liquid crystal layer can have a second alignment state different from the first alignment state. Examples of the first alignment state and / or the second alignment state include a horizontal alignment state, a vertical alignment state, a twist alignment state, a tilt alignment state, and a hybrid alignment state.

[0071] In this specification, the "horizontal alignment state" refers to a state in which the directors of the liquid crystal compound in the liquid crystal layer are aligned approximately parallel to the plane of the liquid crystal layer, and for example, the angle that the directors make with respect to the plane of the liquid crystal layer can be, for example, within the range of approximately -10 degrees to 10 degrees or -5 degrees to 5 degrees, or can be approximately 0 degrees.

[0072] In this specification, the "vertical alignment state" refers to a state in which the directors of the liquid crystal compound in the liquid crystal layer are aligned approximately perpendicular to the plane of the liquid crystal layer, and for example, the angle formed by the directors with respect to the plane of the liquid crystal layer may be, for example, within the range of approximately 80 degrees to 100 degrees or 85 degrees to 95 degrees, or may be approximately 90 degrees.

[0073] In this specification, the term "twisted alignment state" refers to a helical structure in which the directors of liquid crystal compounds in a liquid crystal layer are twisted along a virtual helical axis to form layers. The twisted alignment state can be realized as a vertical, horizontal, or tilted alignment state. That is, the vertical twist alignment mode is a state in which individual liquid crystal compounds are twisted along a helical axis in a vertically aligned state to form layers, the horizontal twist alignment mode is a state in which individual liquid crystal compounds are twisted along a helical axis in a horizontally aligned state to form layers, and the tilted twist alignment mode is a state in which individual liquid crystal compounds are twisted along a helical axis in a tilted state to form layers.

[0074] In this specification, the term "hybrid alignment state" may refer to an alignment state in which the tilt angle, which is the angle between the director of a liquid crystal compound in a liquid crystal layer and the plane of the liquid crystal layer, gradually increases or decreases along the thickness direction of the liquid crystal layer.

[0075] In one example, the first alignment state may be a twisted alignment state, i.e., the liquid crystal layer may be capable of switching between the twisted alignment and another alignment state through application of external energy.

[0076] In one example, the liquid crystal layer can be switched between a twisted alignment state and a vertical alignment state. In one example, the liquid crystal layer can be in a vertical alignment state when no voltage is applied, and in a twisted alignment state when a voltage is applied. The twisted alignment can be a horizontal twisted alignment.

[0077] The liquid crystal layer may further include a chiral dopant. When the liquid crystal layer includes a chiral agent, a twisted alignment state can be realized. The chiral agent (or chiral dopant) that can be included in the liquid crystal layer is not particularly limited, as long as it can induce the desired twisting without damaging the liquid crystal properties, e.g., nematic regularity. A chiral agent that induces rotation in a liquid crystal compound must at least have chirality in its molecular structure. Examples of chiral agents include compounds with one or more asymmetric carbons, compounds with an asymmetric point on a heteroatom, such as chiral amines or chiral sulfoxides, or compounds with an axially asymmetric, optically active site, such as cumulene or binaphthol. The chiral agent may be a low-molecular-weight compound with a molecular weight of 1,500 or less. As the chiral agent, commercially available chiral nematic liquid crystals, such as chiral dopant liquid crystal S-811 available from Merck or LC756 available from BASF, may be used.

[0078] The application ratio of the chiral dopant can be selected to achieve the desired pitch (P). Generally, the content (wt%) of the chiral dopant can be calculated by the formula 100 / (HTP₁), where HTP represents the helixcal twisting power of the chiral dopant and is expressed in μm. -1 The P is the pitch of the liquid crystal in the twisted alignment state, and may be expressed in μm. The pitch p of the liquid crystal layer can be measured by a measurement method using a wedge cell, specifically, by the method described in "Simple method for accurate measurements of the cholesteric pitch using a stripe-wedge Grandjean-Cano cell" by D. Podolskyy et al. (Liquid Crystals, Vol. 35, No. 7, July 2008, pp. 789-791). The HTP value can be measured by the measurement method using the wedge cell described above. Alternatively, the HTP value can usually be provided by suppliers of the liquid crystal and chiral dopant. The content of the chiral dopant can be determined by taking the desired pitch into consideration with reference to the above method.

[0079] In one example, the pitch (unit: μm) of the liquid crystal in the twisted alignment state may be in the range of 15 μm to 50 μm, and specifically, the pitch may be 16 μm or more, 17 μm or more, 18 μm or more, 19 μm or more, or 20 μm or more, and may be 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, or 30 μm or less.

[0080] The upper substrate of the liquid crystal cell may further include a first electrode layer 10b between the first base layer 10a and the adhesive layer 10c. The first electrode layer 10b may be in contact with the inner surface of the first base layer 10a. The adhesive layer 10c may be in contact with the inner surface of the first electrode layer 10b. The lower substrate of the liquid crystal cell may further include a second electrode layer 20b between the second base layer 20a and the spacer 20c. The second electrode layer 20b may be in contact with the inner surface of the second base layer 20a. The spacer 20c may be in contact with the inner surface of the second electrode layer 20b.

[0081] The first and second electrode layers may act on the liquid crystal layer by applying an external force, such as an electric field, to allow the material contained in the liquid crystal layer to transmit or block incident light. For example, the first and / or second electrode layers may include, but are not limited to, a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as ITO (Indium Tin Oxide). The upper first and / or second electrode layers may be formed by depositing, for example, the conductive polymer, the conductive metal, the conductive nanowire, or a metal oxide such as ITO (Indium Tin Oxide).

[0082] The lower substrate of the liquid crystal cell may further include an alignment film 20d. The alignment film 20d may be present on the spacer 20c. That is, the upper and / or side surfaces of the spacer 20c may be in contact with the alignment film. The lower surface of the spacer 20c may be in contact with the second electrode layer 20b. Because the adhesive layer included in the upper substrate may have liquid crystal alignment properties, the upper substrate may not include an alignment film. That is, the inner surfaces of the first electrode layer 10b and / or adhesive layer 10c may not include an alignment film.

[0083] In this specification, the combination of the first substrate layer, the first electrode layer, and the adhesive layer may be referred to as an upper substrate, and the combination of the second substrate layer, the second electrode layer, the spacer, and the alignment layer may be referred to as a lower substrate. In a liquid crystal cell, the upper substrate does not include a separate alignment layer other than the adhesive layer, and the lower substrate may include an alignment layer.

[0084] 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 this specification, the term "horizontal alignment film" may refer to a layer containing an alignment substance that imparts horizontal alignment force to the liquid crystal compound present in the adjacent liquid crystal layer. In this specification, the term "vertical alignment film" may refer to a layer containing an alignment substance that imparts vertical alignment force to the liquid crystal compound present in the adjacent liquid crystal layer. The pretilt angle of the adjacent liquid crystal compound relative to the vertical alignment film may be within the range of 80° to 90°, 85° to 90°, or approximately 87° to 90°, and the pretilt angle of the adjacent liquid crystal compound relative to the horizontal alignment film may be within the range of 0° to 10°, 0° to 5°, or 0° to 3°. Unlike the adhesive layer, the alignment film may not have adhesive strength to bond the upper and lower substrates. In one example, the peel strength of the alignment film relative to the upper substrate may be close to zero in the state of the liquid crystal cell shown in FIG. 1.

[0085] The alignment film may be a rubbed alignment film or a photo-aligned film. The alignment direction of the alignment film may be the rubbing direction in the case of a rubbed alignment film, or the direction of polarized light in the case of a photo-aligned film. This alignment direction can be confirmed by a detection method using an absorptive linear polarizer. Specifically, the alignment direction can be confirmed by placing an absorptive linear polarizer on one side of the liquid crystal layer with the liquid crystal compound contained in the liquid crystal layer horizontally aligned and measuring the transmittance while rotating the polarizer 360 degrees. In this state, when light is irradiated onto the liquid crystal layer or the absorptive linear polarizer and the brightness (transmittance) is measured from the other side, if the absorption axis or transmission axis coincides with the alignment direction of the liquid crystal alignment film, the transmittance tends to be low. However, the alignment direction can be confirmed by simulation that reflects the refractive index anisotropy of the applied liquid crystal compound. Methods for determining the alignment direction depending on the mode of the liquid crystal layer are well known, and the alignment direction of the alignment film can be confirmed using such a known method in this application.

[0086] Examples of the alignment film include materials known to exhibit alignment ability through rubbing alignment, such as polyimide compounds, poly(vinyl alcohol) compounds, poly(amic acid) compounds, polystyrene (polystylene) compounds, polyamide compounds, and polyoxyethylene compounds, as well as polyimide compounds, polyamic acid compounds, polynorbornene compounds, phenylmaleimide copolymer compounds, polyvinylcinamate compounds, polyazobenzene compounds, polyethyleneimide compounds, polyvinylalcohol compounds, polyamide compounds, polyethylene compounds, polystyrene (polystylene) compounds, polyphenylenephthalamide compounds, polyester compounds, and CMPI (chloromethylated The material may include, but is not limited to, one or more selected from the group consisting of materials known to be capable of exhibiting alignment ability upon light irradiation, such as a polyimide compound, a PVCI (polyvinyl cinnamate) compound, and a polymethyl methacrylate compound.

[0087] The spacers 20c can maintain the distance between the upper and lower substrates, and the liquid crystal layer can exist in the area where there are no spacers between the upper and lower substrates.

[0088] The spacers may be patterned. The spacers may have a column or partition wall shape. In one example, the spacers may have a partition wall shape. When the spacers have a partition wall shape, this may be advantageous in terms of maintaining the height of the liquid crystal cell and improving the physical rigidity of the liquid crystal cell. The partition walls may divide the space between the lower and upper substrates into two or more spaces. In areas where there are no spacers, other films or layers present underneath may be exposed. For example, the second electrode layer may be exposed in areas where there are no spacers. An alignment film may cover the spacers and the second electrode layer exposed in areas where there are no spacers. In a liquid crystal cell in which the upper and lower substrates are bonded together, the alignment film present on top of the spacers of the lower substrate and the adhesive layer of the upper substrate may be in contact with each other.

[0089] The spacer-free region between the upper and lower substrates may contain the liquid crystal compound and the above-mentioned additives, such as dichroic dyes, chiral agents, etc. The shape of the spacer is not particularly limited, and may be any shape, such as a circle, ellipse, or other polygonal shape, having multiple faces.

[0090] The spacer may include a curable resin. The type of curable resin is not particularly limited, and may be, for example, a thermosetting resin or a photocurable resin, such as a UV-curable resin. Examples of thermosetting resins include, but are not limited to, silicone resins, silicon resins, furan resins, polyurethane resins, epoxy resins, amino resins, phenolic resins, urea resins, polyester resins, and melamine resins. Examples of UV-curable resins include, but are not limited to, acrylic polymers such as polyester acrylate polymers, polystyrene acrylate polymers, epoxy acrylate polymers, polyurethane acrylate polymers, polybutadiene acrylate polymers, silicone acrylate polymers, and alkyl acrylate polymers.

[0091] The spacers may be formed by a patterning process. For example, the spacers may be formed by a photolithography process. The photolithography process may include a process of applying a curable resin composition to a substrate layer or an electrode layer and then irradiating it with ultraviolet light using a pattern mask. The pattern mask may be patterned with ultraviolet-transmitting and ultraviolet-blocking regions. The photolithography process may further include a process of washing the curable resin composition irradiated with ultraviolet light. The areas irradiated with ultraviolet light are cured, while the areas not irradiated with ultraviolet light remain liquid, which can be removed through a washing process to form a partition wall pattern. In the photolithography process, to easily separate the resin composition from the pattern mask after ultraviolet light irradiation, the pattern mask may be subjected to a release treatment or a release paper may be placed between the resin composition layer and the pattern mask.

[0092] The width (line width), spacing (pitch), thickness, and area of ​​the spacers may be appropriately selected within a range that does not impair the objectives of the present application. For example, the width (line width) of the spacers may be in the range of 10 μm to 500 μm or 10 μm to 50 μm. The spacing (pitch) of the spacers may be in the range of 10 μm to 1,000 μm or 100 μm to 1,000 μm. The area of ​​the spacers may be approximately 5% or more and 50% or less of the total area of ​​the second substrate layer (100%). When the area of ​​the spacers is within the above range, it may be advantageous to ensure excellent electro-optical properties while adequately ensuring adhesion between the upper and lower substrates. The thickness of the spacers may be, for example, in the range of 1 μm to 30 μm or 3 μm to 20 μm.

[0093] The optical device may further include outer substrates bonded to both sides of the liquid crystal cell. The bonding between the liquid crystal cell and the outer substrates may be performed using an adhesive layer. In one example, as shown in FIG. 2, the optical device may include a first outer substrate 101, a first adhesive layer 301, the liquid crystal cell 200, a second adhesive layer 302, and a second outer substrate 102, in that order.

[0094] The outer substrate can be bonded to the liquid crystal cell by a high-temperature, high-pressure autoclave process. During this autoclave process, localized pressure can be applied to the liquid crystal cell including the pressure-sensitive adhesive layer due to uneven melting of the adhesive layer, foreign matter, and shrinkage and expansion of the substrate layer and the polarizer (described below). This pressure on the liquid crystal cell can cause black spots due to pressure applied after autoclaving. According to the present application, by controlling the storage modulus and tangent delta value at 110°C of the pressure-sensitive adhesive layer included in the liquid crystal cell, the pressure applied to the liquid crystal cell is minimal, and the spacer is less likely to penetrate into the pressure-sensitive adhesive layer, preventing black spots due to pressure applied.

[0095] The first outer substrate and the second outer substrate may each independently be an inorganic substrate or a plastic substrate. The inorganic substrate is not particularly limited, and a known inorganic substrate may be used. For example, a glass substrate having excellent light transmittance may be used as the inorganic substrate. Examples of the glass substrate include, but are not limited to, a soda lime glass substrate, a general tempered glass substrate, a borosilicate glass substrate, or an alkali-free glass substrate. Examples of the polymer substrate include cellulose films such as TAC (triacetyl cellulose) or DAC (diacetyl cellulose); COP (cycloolefin copolymer) films such as norbornene derivatives; acrylic films such as PAR (Polyacrylate) or PMMA (poly(methyl methacrylate)); PC (polycarbonate) films; polyolefin films such as PE (polyethylene) or PP (polypropylene); PVA (polyvinyl Examples of materials that can be used include, but are not limited to, sulfone-based films such as PSF (polysulfone) film, PPS (polyphenylsulfone) film, and PES (polyethersulfone) film; PEEK (polyetheretherketone) film; PEI (polyetherimide) film; polyester-based films such as PEN (polyethylenenaphthate) film and PET (polyethyleneterephtalate) film; and fluororesin films. The first and second outer substrates may each have a functional layer, such as a gold or silver coating layer or a silicon compound coating layer such as silicon dioxide or silicon monoxide, or an anti-reflection layer, as needed.

[0096] In one example, the first outer substrate and / or the second outer substrate may be a glass substrate.

[0097] The thickness of each of the first outer substrate and the second outer substrate may be about 0.3 mm or more. In other examples, the thickness may be about 0.5 mm or more, 1 mm or more, 1.5 mm or more, or about 2 mm or more, and may 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.

[0098] The first outer substrate and the second outer substrate may be flat or curved. For example, the first outer substrate and the second outer substrate may both be flat or curved, or one may be flat and the other curved. If both are curved, their curvatures or radii of curvature may be the same or different. The curvatures or radii of curvature herein may be measured using methods known in the art, such as non-contact equipment such as a 2D profile laser sensor, a chromatic confocal line sensor, or a 3D measuring confocal microscope. Methods for measuring the curvatures or radii of curvature using such equipment are well known.

[0099] The first outer substrate and the second outer substrate may have the same sign of curvature. In other words, the first and second outer substrates may be curved in the same direction. That is, in this case, the centers of curvature of the first outer substrate and the second outer substrate are located in the same positions on the top and bottom of the first and second outer substrates. When the first outer substrate and the second outer substrate are curved in the same direction, the first and second outer substrates can be more efficiently bonded with an adhesive layer, and after bonding, a decrease in the adhesion strength between the first and second outer substrates and the liquid crystal cell and / or polarizer can be more efficiently prevented.

[0100] One side of the first adhesive layer may contact the first outer substrate. If no other components (e.g., a first polarizer described below) are further included between the first outer substrate and the liquid crystal cell, the other side of the first adhesive layer may contact the liquid crystal cell; if other components are further included, the other side of the first adhesive layer may contact the other components. One side of the second adhesive layer may contact the second outer substrate. If no other components (e.g., a second polarizer described below) are further included between the second outer substrate and the liquid crystal cell, the other side of the second adhesive layer may contact the liquid crystal cell; if other components are further included, the other side of the second adhesive layer may contact the other components.

[0101] The optical device may further include a first polarizer positioned between the first outer substrate and the liquid crystal cell, and a second polarizer positioned between the second outer substrate and the liquid crystal cell. Figure 2 exemplarily shows an optical device including a first polarizer 401 and a second polarizer 402. Specifically, the first polarizer may be positioned between the first adhesive layer and the liquid crystal cell, and the second polarizer may be positioned between the second adhesive layer and the liquid crystal cell.

[0102] When the optical device further includes a first polarizer and a second polarizer, the optical device may further include a third adhesive layer between the first polarizer and the liquid crystal cell and a fourth adhesive layer between the second polarizer and the liquid crystal cell. FIG. 2 exemplarily illustrates an optical device including a third adhesive layer 303 and a fourth adhesive layer 304. One side of the third adhesive layer may contact the first polarizer, and the other side may contact the liquid crystal cell. One side of the fourth adhesive layer may contact the second polarizer, and the other side may contact the liquid crystal cell. In one example, if a polarizer protective film is formed on one side of the first polarizer facing the third adhesive layer, one side of the third adhesive layer may contact the protective film. In one example, if a polarizer protective film is formed on one side of the second polarizer facing the fourth adhesive layer, one side of the fourth adhesive layer may contact the protective film.

[0103] The term "polarizer" as used herein refers to a film, sheet, or element having a polarizing function. A polarizer is a functional element that can extract light vibrating in one direction from incident light vibrating in various directions.

[0104] The first polarizer and the second polarizer may each be an absorptive polarizer or a reflective polarizer. Herein, an absorptive polarizer refers to an element that exhibits selective transmission and absorption properties for incident light. For example, a polarizer can transmit light that vibrates in one direction from incident light that vibrates in various directions, and absorb light that vibrates in the remaining directions. Herein, a reflective polarizer refers to an element that exhibits selective transmission and reflection properties for incident light. For example, a polarizer can transmit light that vibrates in one direction from incident light that vibrates in various directions, and reflect light that vibrates in the remaining directions.

[0105] The absorptive polarizer may be, but is not limited to, a polarizing layer obtained by dyeing iodine onto a stretched polymer film such as a stretched PVA (poly(vinyl alcohol)) film, or a guest-host polarizing layer in which a liquid crystal polymerized in an oriented state serves as a host and a dichroic dye aligned by the orientation of the liquid crystal serves as a guest.

[0106] The reflective polarizer may be, for example, a reflective polarizing layer known as a DBEF (Dual Brightness Enhancement Film) or a reflective polarizing layer formed by coating a liquid crystal compound such as LLC (Lyotropic liquid crystal), but is not limited thereto.

[0107] The polarizer may be a linear polarizer. As used herein, a linear polarizer refers to a polarizer in which selectively transmitted light is linearly polarized light that vibrates in one direction and selectively absorbed or reflected light is linearly polarized light that vibrates 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.

[0108] A protective film, an anti-reflection film, a retardation film, a surface treatment layer, etc. may be additionally formed on one or both surfaces of the first polarizer and the second polarizer, respectively. The retardation film may be, for example, a quarter-wave plate or a half-wave plate. The quarter-wave plate may have an in-plane retardation value of about 100 nm to 180 nm, 100 nm, or 150 nm for light with a wavelength of 550 nm. The half-wave plate may have an in-plane retardation value of about 200 nm to 300 nm, or 250 nm to 300 nm for light with a wavelength of 550 nm. The retardation film may be, for example, a polymer stretched film or a liquid crystal polymer film. A film made of a known material may be used as the protective film for the polarizer. Examples of such materials include thermoplastic resins with excellent transparency, mechanical strength, thermal stability, moisture blocking properties, and isotropy. Examples of such resins include cellulose resins such as triacetyl cellulose (TAC), polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins such as norbornene resins, polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The first and second protective films may be made of the same material or different materials. Adhesives used to attach the polarizer, retardation film, and protective film include, but are not limited to, acrylic adhesives, isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex adhesives, and water-based polyesters.

[0109] The transmittance of the first polarizer and the second polarizer for 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 for light with a wavelength of 550 nm. The single transmittance of the polarizer can be measured, for example, using a spectrometer (V7100, manufactured by Jasco). For example, with a polarizer sample (excluding the upper and lower protective films) placed in the instrument, air is set to the baseline, and the axis of the polarizer sample is aligned vertically and horizontally with the axis of the reference polarizer, and the transmittance of each is measured, and then the single transmittance can be calculated.

[0110] The light transmission axis of the first polarizer and the light transmission axis of the second polarizer may be perpendicular to each other. Specifically, the angle between the light transmission axis of the first polarizer and the light transmission axis of the second polarizer may be within a range of 80 to 100 degrees or 85 to 95 degrees. If the light transmission axis of the first polarizer and the light transmission axis of the second polarizer are perpendicular to each other, light leakage may occur depending on the distance between the first polarizer and the second polarizer.

[0111] The thickness of each of the first to fourth adhesive layers may be 10 μm or more. The thickness of each of the first to fourth adhesive layers may be 50 μm or more, 100 μm or more, 150 μm or more, 200 μm or more, 250 μm or more, 300 μm or more, 350 μm or more, or 380 μm or more, and may be 2,000 μm or less, 1,800 μm or less, 1,600 μm or less, 1,400 μm or less, 1,200 μm or less, 1,000 μm or less, or 800 μm or less. When the thickness of each adhesive layer is within the above range, defects during the bonding process of the outer substrates are minimized, which may be advantageous in ensuring structural stability and uniform appearance characteristics of the optical device.

[0112] In one example, the thicknesses of the first adhesive layer and the second adhesive layer may be 400 μm or more, 500 μm or more, 600 μm or more, or 700 μm or more, respectively, which may be advantageous in minimizing defects during the bonding process of the outer substrates and ensuring structural stability and uniform appearance characteristics of the optical device.

[0113] In one example, the thickness of each of the third adhesive layer and the fourth adhesive layer may be 380 μm or less, which minimizes the distance between the first polarizer and the second polarizer, thereby reducing light leakage and ensuring the structural stability of the optical device.

[0114] The first to fourth adhesive layers may each have a single-layer structure consisting of a single adhesive layer, or may be a laminate of two or more sub-adhesive layers. The thickness and number of the sub-adhesive layers may be controlled in consideration of the desired thickness of the adhesive layer. For example, the thickness of a single adhesive layer or sub-adhesive layer may be in the range of 100 μm to 500 μm or 300 μm to 400 μm.

[0115] As one example, the storage modulus of each of the first to fourth adhesive layers may be in the range of 1 MPa to 100 MPa. As another example, the storage modulus of each of the first to fourth adhesive layers may be 2 MPa or more or 4 MPa or more, and may be 100 MPa or less, 80 MPa or less, 60 MPa or less, 40 MPa or less, or 20 MPa or less. The storage modulus may be a value measured at a temperature of 25°C and a frequency of 1 Hz.

[0116] For example, the Young's modulus (E) of each of the first to fourth adhesive layers may be in the range of 0.1 MPa to 100 MPa. In other examples, the Young's modulus (E) of the first to fourth adhesive layers may be 0.2 MPa or more, 0.4 MPa or more, 0.6 MPa or more, 0.8 MPa or more, 1 MPa or more, 5 MPa or more, or about 10 MPa or more, and about 95 MPa or less, 80 MPa or less, 75 MPa or less, 70 MPa or less, 65 MPa or less, 60 MPa or less, 55 MPa or less, or about 50 MPa or less. The Young's modulus (E) can be measured, for example, according to the method specified in ASTM D882. The film may be cut into a shape specified in the standard and measured using equipment capable of measuring stress-strain curves (capable of simultaneously measuring force and length), such as a universal testing machine (UTM). Having the Young's modulus of the adhesive layer included in an optical device within the above range may be advantageous in ensuring excellent durability of the optical device. When the adhesive layer is a laminate of at least two or more sub-adhesive layers, each of the sub-adhesive layers can satisfy the above range of Young's modulus.

[0117] For example, the first to fourth adhesive layers may each have a thermal expansion coefficient of 2,000 ppm / K or less. In other examples, the thermal expansion coefficient 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 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, 600 ppm / K or more, 700 ppm / K or more, or about 800 ppm / K or more. The thermal expansion coefficient of the adhesive layer can be measured, for example, according to the specifications of ASTM D696. The thermal expansion coefficient can be calculated by cutting the adhesive layer into the shape specified in the relevant standard and measuring the change in length per unit temperature. It can also be measured by a known method such as TMA (ThermoMechanic Analysis). If the thermal expansion coefficient of the adhesive layer included in the optical device is within the above range, it may be more advantageous to ensure excellent durability of the optical device. When the adhesive layer is a laminate of at least two or more sub-adhesive layers, each of the sub-adhesive layers may satisfy the above range of thermal expansion coefficient.

[0118] The first to fourth adhesive layers may be a thermoplastic polyurethane (TPU) adhesive layer, a polyamide adhesive layer, a polyester adhesive layer, an ethylene vinyl acetate (EVA) adhesive layer, an acrylic adhesive layer, a silicone adhesive layer, or a polyolefin adhesive layer. According to one embodiment of the present application, the first to fourth adhesive layers may be a thermoplastic polyurethane adhesive layer.

[0119] The optical device may further include outer layers surrounding the sides of the liquid crystal cell. Figure 2 exemplarily shows an optical device including outer layers 501 and 502. In the optical device, the area above the liquid crystal cell may be smaller than the area above the first outer substrate or the second outer substrate. Also, the area above the liquid crystal cell may be smaller than the area above the first to fourth adhesive layers included in the optical device.

[0120] In one example, the liquid crystal cell may be encapsulated by the adhesive layer and the outer layer. In this application, the term "encapsulation" may mean covering the entire surface of the liquid crystal cell with the adhesive layer and the outer layer. In one example, if the optical device includes a first adhesive layer and a second adhesive layer, the liquid crystal cell may be encapsulated by the first adhesive layer, the second adhesive layer, and the outer layer. In one example, if the optical device includes a first adhesive layer, a second adhesive layer, a third adhesive layer, and a fourth adhesive layer, the liquid crystal cell may be encapsulated by the third adhesive layer, the fourth adhesive layer, and the outer layer. Such an encapsulation structure significantly improves the durability and weather resistance of the optical device, making it suitable for outdoor applications such as sunroofs.

[0121] The outer layer may include, for example, a thermoplastic polyurethane (TPU) adhesive, a polyamide adhesive, a polyester adhesive, an ethylene vinyl acetate (EVA) 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 adhesive layer.

[0122] This application also relates to a method for manufacturing an optical device. The method for manufacturing the optical device may include a step of autoclaving a laminate including, in order, a first outer substrate, a first adhesive layer, a liquid crystal cell, a second adhesive layer, and a second outer substrate. The liquid crystal cell may be encapsulated through the autoclaving. Unless otherwise specified, the same description of the optical device may be applied to the method for manufacturing the optical device.

[0123] The laminate may further include an outer layer surrounding the side surface of the liquid crystal cell.

[0124] When manufacturing an optical device further including a first polarizer and a second polarizer, the autoclave treatment can be performed on a laminate including, in order, a first outer substrate, a first adhesive layer, a first polarizer, a third adhesive layer, a liquid crystal cell, a second polarizer, a fourth adhesive layer, a second adhesive layer, and a second outer substrate.

[0125] When the optical device further includes elements other than the liquid crystal cell and the polarizer, the laminate can further include the elements other than the liquid crystal cell and the polarizer at desired positions.

[0126] The autoclaving step may be carried out by applying heat and / or pressure to the laminate.

[0127] The autoclave process conditions are not particularly limited and can be performed under appropriate temperature and pressure depending on the type of adhesive layer applied. Typical autoclave processes are performed at temperatures of about 80°C or higher, 90°C or higher, or 100°C or higher, and at pressures of 2 atmospheres or higher, but are not limited thereto. The upper limit of the process temperature can be about 200°C or lower, 190°C or lower, 180°C or lower, or 170°C or lower, and the upper limit of the process pressure can be about 10 atmospheres or lower, 9 atmospheres or lower, 8 atmospheres or lower, 7 atmospheres or lower, or 6 atmospheres or lower.

[0128] The optical device may be a variable transmittance device that can be switched between at least two states with different transmittances. In one example, the variable transmittance device may be a device that can be switched between a transmission mode and a blocking mode.

[0129] The transmittance of the variable transmittance device in the transmission mode may be at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%. Other examples of the transmittance in the transmission mode include 100% or less, 95%, 90%, or 85% or less. However, since a higher transmittance in the transmission mode is more advantageous, there is no particular upper limit.

[0130] In the blocking mode, the transmittance of the variable transmittance device may be 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or 5% or less. In other examples, the transmittance in the blocking mode may be 0% or more, 5% or more, 10% or more, 15% or more, 20% or more, or 25% or more. However, since a lower transmittance is more advantageous in the blocking mode, the lower limit of the transmittance in the blocking mode is not particularly limited.

[0131] The transmittance may be, for example, a rectilinear light transmittance. The rectilinear light transmittance is a percentage of the light transmitted in the same direction as the incident direction to the light incident on the device. For example, if the device is in the form of a film or sheet, the transmittance can be defined as the percentage of light transmitted through the device in the direction aligned with the normal direction of the film or sheet surface, among the light incident in the direction aligned with the normal direction.

[0132] The transmittance may be the transmittance for any one wavelength in the visible light region, for example, within a range of about 400 to 700 nm or about 380 to 780 nm, the transmittance for the entire visible light region, the maximum or minimum transmittance among the transmittances for the entire visible light region, or the average value of the transmittances within the visible light region.

[0133] The optical device may be used in a variety of applications, including, for example, eyewear such as sunglasses, augmented reality (AR) or virtual reality (VR) eyewear, building exterior walls, and vehicle sunroofs. In one example, the optical device may be a vehicle sunroof itself. For example, the optical device may be attached to at least one opening in a vehicle body having the vehicle body, or the vehicle sunroof may be attached to the opening. [Effects of the Invention]

[0134] The present application relates to an optical device, in which the cell gap of a liquid crystal cell is properly maintained, the upper and lower substrates have excellent adhesion, and the optical device can be pressed after a high-temperature and high-pressure autoclave process to prevent black spots. [Brief explanation of the drawings]

[0135] [Figure 1] 1 shows an exemplary liquid crystal cell of the present application. [Figure 2] 1 illustrates an exemplary optical device of the present application. [Figure 3] 1 shows an image of Example 1 after autoclaving. [Figure 4] 1 shows an image of Example 2 after autoclaving. [Figure 5] 1 shows an image of Example 3 after autoclaving. [Figure 6] 1 shows an image of Example 4 after autoclaving. [Figure 7] 1 shows an image of Example 5 after autoclaving. [Figure 8] 1 shows an image of Example 6 after autoclaving. [Figure 9] 1 shows an image of Comparative Example 1 after autoclaving. [Figure 10] 1 shows an image of Comparative Example 2 after autoclaving. [Figure 11] 1 shows an image of Comparative Example 3 after autoclaving. [Figure 12] 10 shows an enlarged image of a black spot in Comparative Example 1 and an example of the principle of black spot occurrence. DETAILED DESCRIPTION OF THE INVENTION

[0136] The present application will be described in detail below through examples, but the scope of the present application is not limited to the following examples.

[0137] Example 1 Fabrication of the upper board An OCA-type adhesive resin (KR3700, Shin-Etsu) was mixed with a toluene solvent to a solids concentration of 25 wt%. A pressure-sensitive adhesive composition was prepared by adding 15 parts by weight of crosslinker A (Tetrakis (Dimethylsiloxy) Silane, Gelest) and 1 part by weight of platinum catalyst (CAT-PL-56, Shin-Etsu) to 100 parts by weight of the adhesive resin. The pressure-sensitive adhesive composition was coated onto a fluorine-containing release film (FSC6, Nippa) using a bar coating method and then heated at 140°C for 6 minutes to form a pressure-sensitive adhesive layer A with a final thickness of approximately 10 μm. The pressure-sensitive adhesive layer was laminated onto the ITO layer of a PET-ITO film to prepare an upper substrate. The PET-ITO film is a film in which an ITO (Indium Tin Oxide) layer is deposited to a thickness of approximately 30 nm on a highly stretched PET (polyethyleneterephtalate) film (OCF, SKC Corporation), with a total thickness of approximately 145 μm. The upper substrate has a structure in which the highly stretched PET film / ITO layer / adhesive layer / release film are laminated in this order.

[0138] Fabrication of the lower board An acrylic resin composition (product name: KAD-03, manufacturer: Minutatek) was coated on the ITO layer of the same PET-ITO film used for the upper substrate, and then photolithography was used to pattern the ITO into a rectangular shape to form a partition wall-like spacer. The partition wall height was 6 μm, the pitch (the distance between two opposing rectangular faces) was 350 μm, and the line width was 15 μm. Next, a vertical alignment film (5661LB3, Nissan) was coated on the spacer to a thickness of approximately 300 nm and then rubbed with a rubbing cloth to produce the lower substrate.

[0139] Liquid crystal cell bonding The fluorine release film was peeled off from the upper substrate. A liquid crystal composition was coated on the alignment layer of the lower substrate, and then laminated with the upper substrate to bond the liquid crystal cell. The liquid crystal composition was a mixture of a liquid crystal compound (SHN-7002XX T12, JNC) with a refractive index anisotropy (Δ) of 0.094 and negative dielectric anisotropy and a chiral additive (S811, Merck). The liquid crystal cell fabricated was a reverse TN mode liquid crystal cell with a cell gap of 6 μm and a chiral pitch of 20 μm.

[0140] Example 2 A liquid crystal cell was manufactured in the same manner as in Example 1, except that adhesive layer B was formed as follows instead of adhesive layer A in Example 1. An OCA-type adhesive resin (KR3700, Shin-Etsu Co.) was mixed with a toluene solvent to a solids concentration of 25 wt%, and an adhesive composition was prepared by adding 10 parts by weight of crosslinker B (n-octadecyltrimethoxysilane, Gelest Co.) and 1 part by weight of platinum catalyst (CAT-PL-56, Shin-Etsu Co.) to 100 parts by weight of the adhesive resin. The adhesive composition was coated on a fluorine release film (FSC6, Nippa Co.) using a bar coating method and then heated at 140°C for 3 minutes to form adhesive layer B with a final thickness of approximately 10 μm.

[0141] Example 3 A liquid crystal cell was manufactured in the same manner as in Example 1, except that adhesive layer C was formed as follows instead of adhesive layer A in Example 1. An OCA-type adhesive resin (KR3700, Shin-Etsu Co., Ltd.) was mixed with a toluene solvent to a solids concentration of 25 wt%. An adhesive composition was prepared by adding 3 parts by weight of crosslinker C (dodecyltrimethoxysilane, Gelest Co., Ltd.) and 1 part by weight of platinum catalyst (CAT-PL-56, Shin-Etsu Co., Ltd.) per 100 parts by weight of the adhesive resin. The adhesive composition was coated onto a fluorine-containing release film (FSC6, Nippa Co., Ltd.) using a bar coating method, and then heated at 140°C for 3 minutes to form adhesive layer C with a final thickness of approximately 10 μm.

[0142] Example 4 A liquid crystal cell was manufactured in the same manner as in Example 1, except that adhesive layer D was formed as follows instead of adhesive layer A in Example 1. An OCA-type adhesive resin (KR3700, Shin-Etsu Co.) was mixed with a toluene solvent to a solids concentration of 25 wt%, and an adhesive composition was prepared by adding 15 parts by weight of crosslinker A (Tetrakis (Dimethylsiloxy) Silane, Gelest Co.) and 1 part by weight of platinum catalyst (CAT-PL-56, Shin-Etsu Co.) to 100 parts by weight of the adhesive resin. The adhesive composition was coated on a fluorine release film (FSC6, Nippa Co.) using a bar coating method and then heated at 140°C for 3 minutes to form adhesive layer D with a final thickness of approximately 10 μm.

[0143] Example 5 A liquid crystal cell was fabricated in the same manner as in Example 1, except that adhesive layer E was formed as follows instead of adhesive layer A in Example 1. An OCA-type adhesive resin (SS9242, KCC) was mixed with a toluene solvent to a solids concentration of 25 wt%. An adhesive composition was prepared by adding 1 part by weight of crosslinker D (S0016B, KCC), 3 parts by weight of crosslinker E (SC0025B, KCC), and 1 part by weight of platinum catalyst (SK0010C, KCC) to 100 parts by weight of the adhesive resin. The adhesive composition was coated onto a fluorine-containing release film (FSC6, Nippa) using a bar coating method and then heated at 140°C for 6 minutes to form adhesive layer E with a final thickness of approximately 10 μm.

[0144] Example 6 A liquid crystal cell was fabricated in the same manner as in Example 1, except that adhesive layer F was formed as follows instead of adhesive layer A in Example 1. An OCA-type adhesive resin (SS9242, KCC) was mixed with a toluene solvent to a solids concentration of 25 wt%. A pressure-sensitive adhesive composition was prepared by adding 0.5 parts by weight of crosslinker D (S0016B, KCC), 3.5 parts by weight of crosslinker E (SC0025B, KCC), and 1 part by weight of platinum catalyst (SK0010C, KCC) to 100 parts by weight of the adhesive resin. The pressure-sensitive adhesive composition was coated onto a fluorine-containing release film (FSC6, Nippa) using a bar coating method and then heated at 140°C for 6 minutes to form adhesive layer F with a final thickness of approximately 10 μm.

[0145] Comparative Example 1 A liquid crystal cell was fabricated in the same manner as in Example 1, except that adhesive layer G was formed as follows instead of adhesive layer A in Example 1. An OCA-type adhesive resin (KR3700, Shin-Etsu Co.) was mixed with a toluene solvent to a solids concentration of 25 wt%, and an adhesive composition was prepared by adding 15 parts by weight of crosslinker A (Tetrakis (Dimethylsiloxy) Silane, Gelest Co.) and 1 part by weight of platinum catalyst (CAT-PL-56, Shin-Etsu Co.) to 100 parts by weight of the adhesive resin. The adhesive composition was coated onto a fluorine-containing release film (FSC6, Nippa Co.) using a bar coating method and then heated at 140°C for 1 minute to form adhesive layer G with a final thickness of approximately 10 μm.

[0146] Comparative Example 2 A liquid crystal cell was fabricated in the same manner as in Example 1, except that adhesive layer H was formed as follows instead of adhesive layer A in Example 1. An OCA-type adhesive resin (KR3700, Shin-Etsu Co.) was mixed with a toluene solvent to a solids concentration of 25 wt%, and an adhesive composition was prepared by adding 15 parts by weight of crosslinker A (Tetrakis (Dimethylsiloxy) Silane, Gelest Co.) and 1 part by weight of platinum catalyst (CAT-PL-56, Shin-Etsu Co.) to 100 parts by weight of the adhesive resin. The adhesive composition was coated onto a fluorine-containing release film (FSC6, Nippa Co.) using a bar coating method and then heated at 130°C for 3 minutes to form adhesive layer H with a final thickness of approximately 10 μm.

[0147] Comparative Example 3 A liquid crystal cell was fabricated in the same manner as in Example 1, except that adhesive layer I was formed as follows instead of adhesive layer A in Example 1. An OCA-type adhesive resin (KR3700, Shin-Etsu Co.) was mixed with a toluene solvent to a solids concentration of 25 wt%, and an adhesive composition was prepared by adding 15 parts by weight of crosslinker A (Tetrakis (Dimethylsiloxy) Silane, Gelest Co.) and 2 parts by weight of platinum catalyst (CAT-PL-56, Shin-Etsu Co.) to 100 parts by weight of the adhesive resin. The adhesive composition was coated onto a fluorine-containing release film (FSC6, Nippa Co.) using a bar coating method and then heated at 140°C for 3 minutes to form adhesive layer I with a final thickness of approximately 10 μm.

[0148] Measurement example 1. Measurement of storage modulus and tangent delta value of adhesive layer The storage modulus and tangent delta value of the adhesive layer were measured using a TA ARES G2 Rheometer. As described in the Examples and Comparative Examples, an adhesive layer was formed on a fluorine release film, and then the fluorine release film was peeled off to remove the adhesive layer. A disk-shaped adhesive layer sample with a diameter of approximately 8 mm and a thickness of approximately 1,000 μm was placed on an Al plate with a diameter of approximately 8 mm and the measurement was carried out. During the measurement, the storage modulus (G') and loss modulus (G") were measured, and the tangent delta value was calculated as G" / G'. The storage modulus and tangent delta values ​​obtained at a frequency of 1 rad / sec and a temperature of 110°C and at a frequency of 1 rad / sec and a temperature of 25°C are listed in Table 1 below.

[0149] Evaluation example 1: Evaluation of black spots after autoclaving A laminate was prepared which included, in order, a first outer substrate 101, a first adhesive layer 301, a first polarizer 401, a third adhesive layer 303, a liquid crystal cell 200, a fourth adhesive layer 304, a second polarizer 402, a second adhesive layer 302 and a second outer substrate 102, and outer layers 501 and 502 surrounding the sides of the liquid crystal cell 200.

[0150] The liquid crystal cells used were those of Examples 1 to 6 and Comparative Examples 1 to 3. The first outer substrate was a glass substrate approximately 3 mm thick, measuring 1100 mm x 800 mm (horizontal x vertical), and having a curvature radius of approximately 2,470R. The second outer substrate was a glass substrate approximately 3 mm thick, measuring 1100 mm x 800 mm (horizontal x vertical), and having a curvature radius of approximately 2,400R. The first and second polarizers were PVA-based polarizers, and the light transmission axes of the first and second polarizers were positioned at approximately 90 degrees. The first and second adhesive layers were each made of a 760 μm-thick TPU layer (Argotec), and the third and fourth adhesive layers were each made of a 380 μm-thick TPU layer (Argotec). The TPU layer (Argotec) had a thermal expansion coefficient of 307 ppm / K, a storage modulus of 3,357,730 Pa, and a loss modulus of 1,485,510 Pa.

[0151] The laminate was autoclaved at a temperature of approximately 110°C and a pressure of approximately 3 atmospheres for three hours to fabricate an optical device with the structure shown in FIG. 2. The optical devices after the autoclaving process were evaluated for the presence or absence of black spots, and the results are listed in Table 1 below. Figures 3 to 8 show images of Examples 1 to 6, respectively, after autoclaving. Figures 9 to 11 show images of Comparative Examples 1 to 3, respectively, after autoclaving. No black spots were observed after autoclaving in Examples 1 to 6, but black spots were observed in Comparative Examples 1 to 3. Figure 12 shows an enlarged image of the black spots in Comparative Example 1 and an example of the mechanism behind the occurrence of black spots (Figure 12(A): before autoclaving; Figure 12(B): after autoclaving; Figure 12(C): enlarged view of the black spots; Figure 12(D): mechanism behind the occurrence of black spots). Figure 12(D) only shows the first base layer 10a, the adhesive layer 10c, the second base layer 20a, and the spacer 20c. In Figure 12 (B) and (C), the areas without black dots are areas where no pressure is applied to the liquid crystal cell, and the areas with black dots are areas where pressure is applied locally to the liquid crystal cell. When localized pressure is applied to a liquid crystal cell, the liquid crystals move due to the pressure (moving in the direction of the arrow in Figure 12 (D)), and the areas that escape appear as black dots, and when the moved liquid crystals gather together, liquid crystal clusters (bright areas around the black dots) occur.

[0152] [Table 1] [Explanation of symbols]

[0153] 10a: First base layer 10b: First electrode layer 10c:Adhesive layer 20a: Second base layer 20b: Second electrode layer 20c:Spacer 20d: Alignment film 30: Liquid crystal layer 101: First outer circuit board 102: Second outer circuit board 200: Liquid crystal cell 301: First adhesive layer 302: Second adhesive layer 303: Third adhesive layer 304: Fourth adhesive layer 401: First polarizer 402: Second polarizer 501, 502: Outer layer

Claims

1. an upper substrate including a first base layer, an adhesive layer, and a first electrode layer; a lower substrate including a second substrate layer and a spacer; and a liquid crystal layer including a liquid crystal compound between an upper substrate and a lower substrate; the adhesive layer is in contact with an inner surface of the first electrode layer, and the inner surface faces a liquid crystal layer; the pressure-sensitive adhesive layer is a liquid crystal aligning pressure-sensitive adhesive layer, The pressure-sensitive adhesive layer has a storage modulus of 18,000 Pa or more at a temperature of 110°C and a frequency of 1 rad / sec, and a tangent delta value of 0.32 or less at a temperature of 110°C and a frequency of 1 rad / sec.

2. The optical device according to claim 1 , further comprising: the first electrode layer between the first substrate layer and the adhesive layer; and a second electrode layer between the second substrate layer and the spacer.

3. The optical device of claim 1 , wherein the upper substrate does not include an alignment film, and the lower substrate further includes an alignment film.

4. The optical device of claim 1 , wherein the adhesive layer comprises a silicone adhesive.

5. 2. The optical device according to claim 1, wherein the pressure-sensitive adhesive layer has a storage modulus in the range of 18,000 Pa to 100,000 Pa at a temperature of 110° C. and a frequency of 1 rad / sec.

6. 2. The optical device according to claim 1, wherein the pressure-sensitive adhesive layer has a tangent delta value in the range of 0.1 to 0.32 at a temperature of 110° C. and a frequency of 1 rad / sec.

7. 2. The optical device according to claim 1, wherein the pressure-sensitive adhesive layer has a storage modulus of 10,000 Pa to 1,100,000 Pa at a temperature of 25° C. and a frequency of 1 rad / sec.

8. 2. The optical device according to claim 1, wherein the pressure-sensitive adhesive layer has a tangent delta value of 0.1 to 2.0 at a temperature of 25° C. and a frequency of 1 rad / sec.

9. The optical device of claim 1 , comprising, in order, a first outer substrate, a first adhesive layer, the liquid crystal cell, a second adhesive layer, and a second outer substrate.

10. The optical device of claim 9 , wherein the first outer substrate and the second outer substrate are glass substrates.

11. 10. The optical device of claim 9, wherein the first adhesive layer and the second adhesive layer are each a thermoplastic polyurethane (TPU) adhesive layer, a polyamide adhesive layer, a polyester adhesive layer, an ethylene vinyl acetate (EVA) adhesive layer, an acrylic adhesive layer, a silicone adhesive layer, or a polyolefin adhesive layer.

12. 10. The optical device of claim 9, further comprising a first polarizer between the first adhesive layer and the liquid crystal cell and a second polarizer between the second adhesive layer and the liquid crystal cell.

13. 13. The optical device of claim 12, wherein the transmission axis of the first polarizer and the transmission axis of the second polarizer are orthogonal to each other.

14. 13. The optical device of claim 12, further comprising a third adhesive layer between the first polarizer and the liquid crystal cell and a fourth adhesive layer between the second polarizer and the liquid crystal cell.

15. 15. The optical device of claim 14, wherein the third adhesive layer and the fourth adhesive layer are each a thermoplastic polyurethane (TPU) adhesive layer, a polyamide adhesive layer, a polyester adhesive layer, an ethylene vinyl acetate (EVA) adhesive layer, an acrylic adhesive layer, a silicone adhesive layer, or a polyolefin adhesive layer.

Images