WO2015046983A1 - Optical film - Google Patents
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- WO2015046983A1 WO2015046983A1 PCT/KR2014/009092 KR2014009092W WO2015046983A1 WO 2015046983 A1 WO2015046983 A1 WO 2015046983A1 KR 2014009092 W KR2014009092 W KR 2014009092W WO 2015046983 A1 WO2015046983 A1 WO 2015046983A1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3016—Polarising elements involving passive liquid crystal elements
Definitions
- the present application relates to an optical film, an optical laminate, and a display device.
- Optically anisotropic films can be used in various applications. Such a film may be used, for example, for adjusting optical characteristics of an LCD (Liquid Crystal Display), improving light utilization efficiency, or securing antireflection and visibility in an organic light emitting device (OLED). In addition, such a film may be used to generate a stereoscopic image or to improve the quality of the stereoscopic image.
- LCD Liquid Crystal Display
- OLED organic light emitting device
- Patent Document 1 Japanese Patent Application Laid-Open No. 1996-321381
- This application provides an optical film, an optical laminate, and a display device.
- One object of the present application is to provide an optical film having a so-called reverse wavelength dispersion characteristic as a single layer by adjusting the arrangement of the liquid crystal compounds in the liquid crystal layer in the optical film including the liquid crystal layer.
- An exemplary optical film may include a liquid crystal layer.
- the liquid crystal layer may include a twisted oriented nematic liquid crystal compound, and the liquid crystal compound may be polymerized in the aligned state to form a liquid crystal layer.
- the twist oriented nematic liquid crystal compound may be abbreviated as TN
- the liquid crystal layer including the TN may be referred to as a TN layer.
- TN is similar to the so-called cholesteric oriented liquid crystal layer (CLC) in that the optical axis of the nematic liquid crystal compound has a helical structure oriented in a layered manner while being twisted along an imaginary spiral axis. It differs from CLC in that the torsion angle is less than 360 degrees.
- the optical axis of the liquid crystal compound may mean a long axis direction of the liquid crystal compound.
- the thickness of the TN layer is less than the pitch due to the difference from the CLC of the TN.
- the term pitch refers to the distance required for TN to complete a 360 degree rotation.
- the CLC has a spiral structure in which the optical axis direction (n in FIG. 1) of the liquid crystal compound is twisted along the spiral axis (X in FIG. 1) in a layered manner.
- the spiral axis is an imaginary line determined according to the CLC.
- the distance (p of FIG. 1) until the optical axis of a liquid crystal compound completes 360 degree rotation is called "pitch.”
- the alignment form is similar to the above CLC, but the rotation angle of the liquid crystal compound is less than 360 degrees because the thickness of the liquid crystal layer is less than the pitch (P in FIG.
- the twist angle of the TN in the TN layer may be in the range of 50 degrees to 300 degrees.
- the torsion angle of the term TN is an angle formed by the optical axis of the liquid crystal compound at the bottom of the TN layer and the optical axis of the liquid crystal compound at the top of the TN layer.
- the term top or bottom of the term TN layer in this application is a concept for determining the relative positional relationship. That is, if one surface of the TN layer is referred to as the bottom, the opposite surface may be defined as top, wherein the surface defined as bottom need not necessarily be at the bottom upon application of the TN layer.
- the twist angle may be at least 60 degrees, at least 70 degrees, or at least 75 degrees in another example.
- the torsion angle is also 290 degrees or less, 280 degrees or less, 270 degrees or less, 260 degrees or less, 250 degrees or less, 240 degrees or less, 230 degrees or less, 220 degrees or less, 210 degrees or less, 200 degrees or less, 190 degrees in another example. Or less, 180 degrees or less, 170 degrees or less, 160 degrees or less, 150 degrees or less, 140 degrees or less, 130 degrees or less, 120 degrees or 110 degrees or less.
- the twist angle can be appropriately changed to suit the application of the optical film.
- the orientation of the TN layer may be further adjusted to secure a desired effect. That is, the change according to the thickness of the rotation angle of the liquid crystal compound rotating along the helix axis in the TN layer, that is, the angle of the optical axis of the liquid crystal compound with respect to the optical axis of the liquid crystal compound at the bottom of the TN layer may be nonlinear.
- a liquid crystal layer having the following purpose that is, a so-called reverse wavelength dispersion characteristic can be formed.
- the thickness change from the lower side to the upper direction of the TN layer is taken as the x-axis, and the angle of the optical axis direction of the liquid crystal compound present in the thickness to the optical axis direction of the liquid crystal compound existing at the bottom of the TN layer
- the graph shown as the axis may be a nonlinear graph.
- the graph is linear (201 of FIG. 2), that is, when a change in the rotation angle of the liquid crystal compound occurs constantly, a desired effect may not be easily secured.
- the graph is non-linear (for example, 202 in FIG. 2), that is, when the change in the rotation angle of the liquid crystal compound is not constant, a desired effect can be secured.
- Such a nonlinear graph-type TN layer may be manufactured by controlling the rotational force (twisting powder) of the nematic liquid crystal compound for each thickness in the manufacturing process, which may be performed by adjusting the concentration of the chiral agent as described below. .
- the slope of the graph includes a portion that increases with increasing thickness of the TN layer (ie, as the x-axis value of the graph increases). It can be represented as a nonlinear graph.
- the TN layer of the present application exhibits so-called reverse wavelength dispersion according to the specific orientation as described above.
- the reverse wavelength dispersion characteristic may mean a state that satisfies Equation 1 below.
- R (650) is the plane retardation of the liquid crystal layer with respect to light of 650 nm wavelength
- R (550) is the plane retardation of the liquid crystal layer with respect to light of 550 nm wavelength
- R (450) is 450 It is a plane phase difference of the said liquid crystal layer with respect to the light of nm wavelength.
- the phase retardation for each wavelength may be determined according to Equation 2 below.
- Equation 2 R ( ⁇ ) is the phase retardation of the TN layer with respect to light having a wavelength of ⁇ nm, d is the thickness of the TN layer, and Nx is the slow axis direction of the TN layer, that is, the direction showing the highest refractive index on the plane.
- R (450) / R (550) and R (650) / R (550) is not particularly limited.
- R (450) / R (550) is 0.81 to 0.99, 0.82 to 0.98, 0.83 to 0.97, 0.84 to 0.96, 0.85 to 0.95, 0.86 to 0.94, 0.87 to 0.93, 0.88 to 0.92 or It may be in the range of 0.89 to 0.91.
- R (650) / R (550) is also within the range of 1.01 to 1.19, 1.02 to 1.18, 1.03 to 1.17, 1.04 to 1.16, 1.05 to 1.15, 1.06 to 1.14, 1.07 to 1.13, 1.08 to 1.12 or 1.09 to 1.11 There may be. In this range, the desired reverse wavelength dispersion characteristic can be secured appropriately.
- the TN layer of the optical film may have 1/4 or 1/2 wavelength phase retardation characteristics.
- the term "n-wavelength phase retardation characteristic" may mean a characteristic capable of retarding incident light by n times the wavelength of the incident light within at least a portion of the wavelength range.
- the plane retardation of the TN layer with respect to light having a wavelength of 550 nm may be about 110 nm to 220 nm or about 140 nm to 170 nm.
- the plane retardation of the TN layer with respect to light having a wavelength of 550 nm may be in the range of 240 nm to 350 nm or 250 nm to 340 nm.
- the helix axis of the TN layer may be formed to be parallel to the thickness direction of the TN layer.
- the term "thickness direction" of the TN layer may mean a direction parallel to an imaginary line connecting the lowermost part and the uppermost part of the TN layer with the shortest distance.
- the optical film further includes a base layer as described below, and the TN layer is formed on one surface of the base layer, the TN layer is formed in a thickness direction of the TN layer. It may be a direction parallel to the imaginary line formed in a direction perpendicular to the plane of the substrate layer.
- angles in the present specification when using terms such as vertical, parallel, orthogonal or horizontal, this means substantially vertical, parallel, orthogonal or horizontal in a range that does not impair the desired effect.
- an error including a manufacturing error or a variation is included.
- each of the above cases may include an error within about ⁇ 15 degrees, an error within about ⁇ 10 degrees or an error within about ⁇ 5 degrees.
- the TN layer may have a thickness, for example, in the range of 0.1 ⁇ m to 10 ⁇ m.
- the other lower limit of the thickness may be 0.5 ⁇ m, 1 ⁇ m, or 1.5 ⁇ m, and the other upper limit may be 9 ⁇ m, 8 ⁇ m, 7 ⁇ m, 6 ⁇ m, 5 ⁇ m, or 4 ⁇ m.
- the TN layer may include a liquid crystal polymer.
- An exemplary method for producing a TN layer is a composition comprising a polymerizable liquid crystal compound and a polymerizable or non-polymerizable chiral agent, and inducing the rotation of the liquid crystal compound by the chiral agent. May be formed by polymerization, in which case the TN layer may comprise a polymerized liquid crystal polymer.
- One exemplary TN layer may include a compound represented by Chemical Formula 1 in a polymerized form.
- A is a single bond, -COO- or -OCO-
- R 1 to R 10 are each independently hydrogen, halogen, alkyl group, alkoxy group, cyano group, nitro group, -OQP or a substituent of Formula 2
- At least one of R 1 to R 10 is -OQP or a substituent of Formula 2, wherein Q is an alkylene group or an alkylidene group, and P is an alkenyl group, epoxy group, cyano group, carboxyl group, or acryloyl group. , Methacryloyl group, acryloyloxy group or methacryloyloxy group.
- B is a single bond, -COO- or -OCO-
- R 11 to R 15 are each independently hydrogen, halogen, alkyl group, alkoxy group, cyano group, nitro group or -OQP
- R 11 to R At least one of 15 is -OQP, wherein Q is an alkylene group or an alkylidene group, P is an alkenyl group, epoxy group, cyano group, carboxyl group, acryloyl group, methacryloyl group, acryloyloxy group or meta It is a chryloyloxy group.
- single bond in the formulas (1) and (2) means a case where no separate atom is present in the moiety represented by A or B.
- A is a single bond in Formula 1, benzene on both sides of A may be directly connected to form a biphenyl structure.
- halogen in the general formula (1) and (2) chlorine, bromine or iodine may be exemplified.
- the alkyl group may be a straight or branched chain alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, or 3 to 20 carbon atoms, 3 to 16 carbon atoms, or Cycloalkyl groups having 4 to 12 carbon atoms can be exemplified.
- the alkyl group may be optionally substituted by one or more substituents.
- an alkoxy group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms may be exemplified.
- the alkoxy group may be linear, branched or cyclic.
- the alkoxy group may be optionally substituted by one or more substituents.
- alkylene group or the alkylidene group in the formulas (1) and (2) an alkylene group or an alkylidene group having 1 to 12 carbon atoms, 4 to 10 carbon atoms or 6 to 9 carbon atoms may be exemplified.
- the alkylene group or alkylidene group may be linear, branched or cyclic.
- the alkylene group or alkylidene group may be optionally substituted by one or more substituents.
- alkenyl groups having 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms may be exemplified.
- the alkenyl group may be linear, branched or cyclic.
- the alkenyl group may be optionally substituted by one or more substituents.
- Examples of the substituent that may be substituted with an alkyl group, alkoxy group, alkenyl group, alkylene group or alkylidene group include alkyl, alkoxy, alkenyl, epoxy, cyano, carboxyl, acryloyl, methacryloyl, Acryloyloxy group, methacryloyloxy group or an aryl group may be exemplified, but is not limited thereto.
- P may be an acryloyl group, methacryloyl group, acryloyloxy group or methacryloyloxy group, may be an acryloyloxy group or methacryloyloxy group, in another example acryloyloxy group Can be.
- At least one of -OQP or residues of formula (2) which may be present in Formulas (1) and (2), may be, for example, at a position of R 3 , R 8, or R 13 , for example one or two May exist.
- a substituent other than -OQP or the residue of Formula 2 is, for example, hydrogen, halogen, a straight or branched chain alkyl group having 1 to 4 carbon atoms, and a cycloalkyl having 4 to 12 carbon atoms.
- It may be an alkyl group, a cyano group, an alkoxy group having 1 to 4 carbon atoms, a cyano group or a nitro group, preferably chlorine, a straight or branched chain alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 4 to 12 carbon atoms, and 1 to 4 carbon atoms. It may be an alkoxy group or cyano group.
- any liquid crystal for example, may be used without particular limitation, as long as it can induce a desired rotation without compromising nematic regularity.
- the chiral agent for inducing rotation in the liquid crystal needs to include at least chirality in the molecular structure.
- the chiral agent for example, compounds having one or two or more asymmetric carbons, compounds having asymmetric points on heteroatoms such as chiral amines or chiral sulfoxides, or cumulene Or a compound having an axially asymmetric, optically active site with an axial agent such as binaphthol.
- the chiral agent may be, for example, a low molecular weight compound having a molecular weight of 1,500 or less.
- a commercially available chiral nematic liquid crystal for example, a chiral dopant liquid crystal S-811 commercially available from Merck or LC756 of BASF may be used.
- the optical film may further include a base layer, and a TN layer may be formed on one surface of the base layer.
- a transparent substrate layer such as glass or transparent plastic substrate layer
- the plastic base layer include a cellulose base layer such as a diacetyl cellulose (DAC) or a triacetyl cellulose (TAC) base layer; COP (cyclo olefin copolymer) base layers, such as a norbornene derivative resin base layer; An acrylic base layer such as a poly (methyl methacrylate) base layer; a polycarbonate (PC) base layer; an olefin base layer such as a polyethylene (PE) or polypropylene (PP) base layer; a polyvinyl alcohol (PVA) base layer; ether sulfone (PET) base layer; PEEK (polyetheretherketone) base layer; PEI (polyetherimide) base layer; PEN (polyethylenenaphthatlate) base layer; polyester base layer such as PET (polyethyleneterephtalate) base layer; PI (polyimide) base layer
- DAC diacety
- the substrate layer may be subjected to various surface treatments such as a low reflection treatment, an antireflection treatment, an antiglare treatment, and / or a high resolution antiglare treatment, as necessary.
- the optical film may further include an alignment layer.
- the term alignment layer may refer to a layer that exhibits surface alignment characteristics that improve or provide alignment uniformity in the process of forming the liquid crystal layer, or generate alignment of the waveguide of the liquid crystal.
- the alignment layer may be, for example, a resin film that provides a plurality of patterned groove regions, a photo alignment layer, or a rubbing treatment film such as a rubbing treatment polyimide.
- the alignment layer 102 is, for example, when the optical film 100 includes the base layer 101 as shown in FIG. 4, the surface of the base layer 101, for example, the base layer 101. And between the TN layer 103.
- a method of imparting orientation to the substrate layer may be used by simply rubbing or stretching the substrate layer or providing hydrophilicity to the surface thereof without forming a separate alignment layer. For example, if the substrate layer has a wetting angle in the above range, the substrate layer may exhibit properties that can control the orientation of the TN in a desired range without the alignment layer.
- the present application also relates to a method of manufacturing such an optical film.
- the manufacturing method may include, for example, inducing a concentration change according to the thickness of the coating layer of the chiral agent on a liquid crystal coating layer including a nematic liquid crystal compound, a chiral agent, and a polymerization initiator, and a state where the concentration change of the chiral agent is induced. It may include the step of polymerizing the nematic liquid crystal compound.
- the liquid crystal coating layer may be formed by coating a coating liquid (TN composition) including a nematic liquid crystal compound, for example, the compound of Formula 1 and a chiral agent together with a polymerization initiator.
- TN composition a coating liquid including a nematic liquid crystal compound, for example, the compound of Formula 1 and a chiral agent
- the TN composition may be part of a coating composition, typically including one or more solvents.
- the coating composition may optionally include additional components such as, for example, dispersants, antioxidants and anti-ozonants.
- the coating composition may include various dyes and pigments, if desired, to absorb ultraviolet, infrared or visible light. In some cases, it may be appropriate to add viscosity modifiers such as thickeners and fillers.
- the TN composition can be applied by various liquid coating methods.
- the TN composition is polymerized or converted to a TN layer.
- Such conversion may include evaporation of the solvent, heating to align the TN material; Crosslinking of TN compositions; Or application of heat, for example actinic radiation; It can be accomplished by a variety of techniques, including irradiation of light such as ultraviolet, visible or infrared light and irradiation of electron beams, or combinations thereof or curing of the TN composition using similar techniques.
- the TN composition may include the compound of Formula 1, a polymerization initiator, and a chiral agent.
- generates a radical by heat or light can be used, for example.
- a radical initiator is for initiating the polymerization or crosslinking of the nematic liquid crystal compound.
- a general component known in the art may be appropriately selected and used.
- 2-methyl-1- [4- (methylthio) phenyl] -2- (4-morpholinyl) -1-propaneone (2-methyl-1- [4- ( methylthio) phenyl] -2- (4-morpholinyl) -1-propanone), 2-dimethoxy-1,2-diphenylethan-1-one (2-dimethoxy-1,2-diphenylethan-1-one), 1-hydroxy-cyclohexyl-phenyl-ketone, Triaryl sulfonium hexafluoroantimonate salts and diphenyl (2,4,6- Trimethylbenzoyl) -phosphine oxide (diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide) and the like may be used one or two or more selected from, but is not limited thereto.
- the TN composition may include the radical initiator in a ratio of 0.1 part by weight to 10 parts by weight with respect to 100 parts by weight of the liquid crystal compound.
- the radical initiator By controlling the content of the radical initiator as described above, effective polymerization and crosslinking of the liquid crystal compound can be induced, and deterioration of physical properties by the remaining initiator after polymerization and crosslinking can be prevented.
- the unit weight part may mean a ratio of the weight of each component, unless otherwise specified.
- the chiral agent for example, compounds of the aforementioned kind can be used.
- the TN composition may include a chiral agent in a proportion of 0.1 parts by weight to 10 parts by weight with respect to 100 parts by weight of the liquid crystal compound.
- the TN composition may further comprise a solvent as needed.
- a solvent for example, Halogenated hydrocarbons, such as chloroform, dichloromethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene; Aromatic hydrocarbons such as benzene, toluene, xylene, methoxy benzene and 1,2-dimethoxybenzene; Alcohols such as methanol, ethanol, propanol, isopropanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and cyclopentanone; Cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve; And ethers such as diethylene glycol dimethyl ether (DEGDME) and dipropylene glycol dimethyl ether (DPGDME).
- DEGDME diethylene glycol
- the TN composition may further include a surfactant.
- the surfactant is distributed on the surface of the liquid crystal to not only make the surface uniform, but also stabilize the liquid crystal orientation to keep the surface of the film smooth after formation of the TN layer, thereby improving appearance quality.
- a fluorocarbon surfactant and / or a silicone-based surfactant may be used.
- a surfactant of the fluorocarbon series is a 3M Co. product fluoro rod (Fluorad) FC4430 TM, fluoro lard FC4432 TM, fluoro lard FC4434 TM and Dupont Corp. product, Zonyl (Zonyl) and the like may be used, a surfactant of silicon-based BYK TM manufactured by BYK-Chemie may be used.
- the content of the surfactant is not particularly limited and may be appropriately selected in consideration of coating efficiency and drying efficiency.
- the TN layer may be formed by polymerizing the liquid crystal compound in a state in which a concentration gradient of the chiral agent is induced.
- the TN layer is formed by irradiating relatively weak ultraviolet rays to the coating layer of the TN composition to form a concentration gradient of the chiral agent, and irradiating relatively strong ultraviolet rays to the coating layer on which the concentration gradient is formed. It may include polymerizing the components of.
- the concentration gradient of the chiral agent may be formed along the thickness direction of the coating layer. Irradiation of ultraviolet rays that form a concentration gradient of the chiral agent may be performed, for example, at a temperature range of about 40 ° C. to 80 ° C., 50 ° C. to 70 ° C., or about 60 ° C.
- the irradiation of ultraviolet rays for the formation of the concentration gradient may be performed by irradiating the ultraviolet rays of the wavelength of the A region with a light amount of about 10 mJ / cm 2 to 500 mJ / cm 2 .
- the amount of light is about 50 mJ / cm 2 to 400 mJ / cm 2 , about 50 mJ / cm 2 to 300 mJ / cm 2 , about 50 mJ / cm 2 to 200 mJ / cm 2 , for the formation of a more effective concentration gradient.
- an amount of ultraviolet light sufficient to polymerize the components of the composition may be irradiated to form the TN layer.
- the coating layer may be fixed in a state in which the liquid crystal has a different pitch according to the concentration gradient of the formed chiral agent, thereby forming a TN region.
- the conditions for the irradiation of the strong ultraviolet light are not particularly limited as long as the polymerization of the components of the composition is sufficiently advanced.
- the ultraviolet irradiation may be performed by irradiating with a light amount of about 0.5 J / cm 2 to 10 J / cm 2 .
- the wavelength of the ultraviolet ray irradiated at this time is not particularly limited as long as sufficient polymerization can occur, and for example, light in the ultraviolet rays A to V regions can be irradiated.
- the coating layer of the TN composition may be formed on a suitable substrate layer.
- the coating layer of the TN composition may be formed on the alignment layer formed on the base layer.
- the alignment layer may be formed by, for example, forming a polymer film such as polyimide on a substrate layer, rubbing treatment, coating a photo-alignment compound, or performing an alignment treatment through irradiation of linearly polarized light, or an imprinting method such as nanoimprinting. Can be formed in a manner.
- Optical films comprising such TN layers can be applied to a variety of applications, as such or in combination with other elements.
- the present application is directed to an optical laminate comprising the optical film and other elements.
- Such an optical laminate may be applied to, for example, an LCD, an OLED, or the like, or may be applied to the implementation of a stereoscopic image or the improvement of its quality.
- the optical laminate may include a retardation film as the other element.
- a retardation film various elements can be selected depending on the application without particular limitation.
- a so-called A plate known as a half wave plate (HWP) or a quarter wave plate (QWP) or the like can be used.
- the retardation film may be a polymer film provided with retardation by stretching or the like, or may be a liquid crystal film.
- the optical axis of the liquid crystal of the TN layer of the optical film and the slow axis of the retardation film may be variously set according to the application.
- the angle formed by the slow axis of the retardation film in the laminate and the optical axis of the nematic liquid crystal compound positioned closest to the retardation film in the TN layer is in the range of about 5 degrees to 90 degrees or about 10 degrees to 70 degrees. Can be in.
- the optical laminate may further include a polarizing layer.
- Such an optical laminate may include, for example, a polarizing layer 401, a retardation film 402, and an optical film 403 as shown in FIG. 4.
- an angle formed between the light absorption axis of the polarizing layer 401 and the slow axis of the retardation film 402 may be in a range of 10 degrees to 20 degrees.
- the angle formed by the slow axis of the retardation film 402 and the optical axis of the nematic liquid crystal compound positioned nearest to the retardation film in the TN layer of the optical film 403 may be in a range of 8 degrees to 16 degrees.
- the twist angle of the TN layer may be in the range of 36 degrees to 50 degrees.
- the optical laminated body of such a structure can be applied to various uses, for example, can be used as an anti-reflective polarizing plate of OLED.
- the optical laminate may include a polarization layer 401, the optical film 403, and the retardation film 402 sequentially disposed as shown in FIG. 5.
- the light absorption axis of the polarizing layer 401 and the slow axis of the retardation film 402 may be perpendicular or horizontal to each other.
- the optical axis of the liquid crystal compound closest to the retardation film in the TN layer of the optical film 403 is the retardation film (
- An angle with the slow axis of 402 may be in the range of about 50 degrees to 70 degrees or about 55 degrees to 67 degrees. Also in this case the torsion angle of the TN layer may be in the range of about 10 degrees to 30 degrees.
- the optical axis of the liquid crystal compound closest to the retardation film in the TN layer of the optical film 403 is the retardation.
- the angle with the slow axis of the film 402 may be in the range of about 15 degrees to 35 degrees or about 17 degrees to 32 degrees.
- the twist angle of the TN layer may also be in the range of about 60 degrees to 85 degrees.
- the optical laminated body of such a structure can be applied to various uses, for example, can be used as an anti-reflective polarizing plate of OLED.
- the optical laminate may include a polarizing layer as the other element.
- an absorbing polarizing layer or a reflective polarizing layer may be applied as the polarizing layer.
- the kind of absorption type or reflection type polarizing layer that can be used above is not particularly limited.
- a known polarizing layer of PVA (polyvinyl alcohol) film series may be used as the absorbing polarizing layer
- the reflecting polarizing layer may be made of LLC (Lyotrophic Liquid Crystal) or CLC (Cholesteric Liquid Crystal).
- DBEF dual brightness enhancement film
- WGP wire grid polarizer
- FIG. 6 is a cross-sectional view of an exemplary optical laminate, and illustrates a case including a polarizing layer 601 and the optical film 602 disposed on one surface of the polarizing layer 601.
- the polarization layer 601 may be a reflection type or an absorption type polarization layer.
- the angle between the optical axis of the liquid crystal compound closest to the polarizing layer in the TN layer and the light absorption axis or the light reflection axis of the polarizing layer in the optical film is within a range of 5 degrees to 15 degrees. , 95 degrees to 105 degrees.
- the torsion angle of the TN layer in the above may be in the range of 80 degrees to 100 degrees.
- the optical laminate may include an absorbing polarizing layer and a reflective polarizing layer at the same time.
- FIG. 7 shows an exemplary structure of the optical laminate, in which the absorption type polarizing layer 6011, the reflective type polarizing layer 6012, and the optical film 602 are sequentially disposed. Unlike the structure shown in FIG. 7, the absorbing polarizing layer 6011 may be disposed adjacent to the optical film 602 as compared to the reflective polarizing layer 6012.
- the light absorption axis of the absorption type polarizing layer and the light reflection axis of the reflection type polarizing plate may be parallel to each other.
- the angle between the optical axis of the liquid crystal compound and the light absorption axis or the light reflection axis of the polarization layer closest to the absorption or reflection polarization layer in the TN layer is in the range of 5 to 15 degrees, or 95 to 105 degrees. It may be in the range of the figure.
- the torsion angle of the TN layer in the above may be in the range of 80 degrees to 100 degrees.
- the optical laminated body of such a structure can be used, for example as an antireflection film in OLED or a reflective LCD, or a brightness improving film in LCD.
- the optical laminate as described above may be formed by laminating the optical film of the present application and the polarizing layer or the retardation film using an adhesive or an adhesive, or directly coating the aforementioned TN composition on the polarizing layer or the retardation film to form a coating layer. It can also superpose
- the present application also relates to a display device.
- An exemplary display device may include the optical film or the optical laminate.
- the specific kind of the display device including the optical laminate is not particularly limited.
- the device may be, for example, an LCD or an OLED.
- the arrangement of the optical film or the optical lamination in the display device is not particularly limited, and for example, a known form may be employed.
- the optical film or the optical stack when applied for changing the optical properties or for the anti-reflection effect, it may be disposed adjacent to the front of the display device or the reflective electrode layer of the OLED and the like.
- the optical film or the optical laminate when applied as a brightness enhancement film in an LCD or the like, the optical film or the optical laminate may be located between the display panel and the light source.
- the liquid crystal layer may be a single layer through control of the alignment state of the liquid crystal compound in the liquid crystal layer, and the liquid crystal layer may exhibit so-called reverse wavelength dispersion characteristics even at a thin thickness.
- the optical film including the liquid crystal layer exhibits optical modulation characteristics in a display device such as an LCD (Liquid Crystal Display) or an OLED (Organic Light Emitting Device), or an optical element or a stereoscopic image capable of improving light utilization efficiency. It may be used for various purposes such as an element for improving the quality thereof.
- 1 is a conceptual diagram for explaining the orientation of a liquid crystal compound.
- FIG 3 is an exemplary cross-sectional view of an optical film.
- 4 to 7 are views showing various structures of the optical laminate.
- optical film will be described in detail through Examples and Comparative Examples, but the scope of the film is not limited by the following Examples.
- a liquid crystal composition was prepared in the following manner.
- RM1230 a composition without chiral dopant
- RM1231 a composition containing chiral dopant
- Merck's RM reactive mesogen
- CLC horesteric liquid crystals
- a photopolymerization initiator (Irgacure 907) having a maximum absorption wavelength in the range of 280 nm to 320 nm is blended at a ratio of 3% by weight of the solid content of RM, and the maximum absorption wavelength is 360 nm to 400 nm.
- Photopolymerization initiator (Darocure TPO) in the range was blended at a rate of 0.4% by weight of solids of RM. Thereafter, the mixture was heated at a temperature of about 60 ° C. for about 1 hour, and then cooled sufficiently to prepare a uniform solution.
- the prepared liquid crystal composition was deposited on the alignment layer using wire bar No. 6 was used and dried at 100 ° C. for about 2 minutes. Thereafter, using an ultraviolet irradiation equipment (TLK40W / 10R, manufactured by Philips), the coating layer was irradiated with ultraviolet light having a wavelength in the range of 350 nm to 400 nm at a temperature of about 60 ° C. at a light amount of about 100 mJ / cm 2 . A gradient of concentration of the laurel was induced.
- TLK40W / 10R ultraviolet irradiation equipment
- the TN layer having a thickness gradient of about 3 ⁇ m was irradiated with a strong ultraviolet ray at a light amount of 1 mJ / cm 2 or more so that polymerization of RM is sufficiently caused by an ultraviolet irradiation equipment (Fusion UV, 400 W) to the coating layer having a concentration gradient induced. Formed.
- the twist angle of the TN layer was about 90 degrees, and showed nonlinear characteristics as shown by 202 of FIG. 2.
- the wavelength dispersion characteristics of the liquid crystal layers of the liquid crystal films prepared in Examples and Comparative Examples were checked using Axoscan (Axometrics) equipment, and the results are shown in FIG. 8.
- Axoscan Axometrics
- the optical films of Examples and Comparative Examples have the same torsion angle as shown in FIG. 8, Example 1 exhibiting nonlinear graph characteristics through the induction of the concentration gradient of the chiral agent, the so-called reverse wavelength dispersion characteristics are realized, but the optical of Comparative Example 1 It can be seen that the film has a real wavelength characteristic.
- the result of the embodiment in FIG. 8 is where R 650 / R 550 is greater than one.
- the optical film of Example 1 can be applied to various applications requiring a quarter wave plate or a half wave plate and the like through the reverse wavelength dispersion property to exhibit excellent characteristics.
Abstract
Description
Claims (20)
- 콜레스테릭 배향된 네마틱 액정 화합물들을 포함하며, 두께가 상기 콜레스테릭 배향된 네마틱 액정 화합물의 피치 미만이고, 비틀림 각도가 50도 내지 300도의 범위 내에 있는 액정층을 포함하고, 상기 액정층은, 하기 수식 1을 만족하는 광학 필름:And a liquid crystal layer comprising cholesteric oriented nematic liquid crystal compounds, wherein the thickness is less than the pitch of the cholesteric oriented nematic liquid crystal compound, and the twist angle is within a range of 50 degrees to 300 degrees. Silver, an optical film satisfying the following formula 1:[수식 1][Equation 1]R(650)/R(550) > R(550)/R(550) > R(450)/R(550)R (650) / R (550)> R (550) / R (550)> R (450) / R (550)수식 1에서 R(650)은 650 nm 파장의 광에 대한 상기 액정층의 면상 위상차이고, R(550)은 550 nm 파장의 광에 대한 상기 액정층의 면상 위상차이며, R(450)은, 450 nm 파장의 광에 대한 상기 액정층의 면상 위상차이다.In Equation 1, R (650) is the plane retardation of the liquid crystal layer with respect to light of 650 nm wavelength, R (550) is the plane retardation of the liquid crystal layer with respect to light of 550 nm wavelength, and R (450) is 450 It is a plane phase difference of the said liquid crystal layer with respect to the light of nm wavelength.
- 제 1 항에 있어서, R(650)/R(550)이 1.01 내지 1.19의 범위 내에 있고, R(450)/R(550)이 0.81 내지 0.99의 범위 내에 있는 광학 필름.The optical film of claim 1, wherein R (650) / R (550) is in the range of 1.01 to 1.19, and R (450) / R (550) is in the range of 0.81 to 0.99.
- 제 1 항에 있어서, 액정층의 두께를 x축으로 하고, 해당 두께에 존재하는 액정 화합물의 광축과 액정층의 최하부(x가 0인 위치)에 존재하는 액정 화합물의 광축이 이루는 각도를 y축하여 도시한 그래프가 비선형 그래프로 나타나는 광학 필름.2. The thickness of the liquid crystal layer according to claim 1, wherein the thickness of the liquid crystal layer is set as the x axis, and the y axis of the angle formed between the optical axis of the liquid crystal compound existing at the thickness and the optical axis of the liquid crystal compound existing at the bottom of the liquid crystal layer (where x is 0). Optical film in which the graph shown is a non-linear graph.
- 제 3 항에 있어서, 그래프는 기울기가 액정층의 두께 증가함에 따라서 증가하는 부위를 포함하는 광학 필름.The optical film of claim 3, wherein the graph includes a portion where the slope increases as the thickness of the liquid crystal layer increases.
- 제 1 항에 있어서, 액정층의 550 nm의 파장의 광에 대한 면상 위상차가 110 nm 내지 220 nm의 범위 내 또는 240 nm 내지 350 nm의 범위 내에 있는 광학 필름.The optical film according to claim 1, wherein the planar phase difference with respect to light having a wavelength of 550 nm of the liquid crystal layer is in the range of 110 nm to 220 nm or in the range of 240 nm to 350 nm.
- 제 1 항에 있어서, 액정층은 두께가 0.1 ㎛ 내지 10 ㎛의 범위 내인 광학 필름.The optical film of claim 1, wherein the liquid crystal layer has a thickness in the range of 0.1 μm to 10 μm.
- 제 1 항에 있어서, 액정층은 키랄제를 추가로 포함하는 광학 필름.The optical film of claim 1, wherein the liquid crystal layer further comprises a chiral agent.
- 제 1 항에 있어서, 액정층의 일면에 형성되는 기재층을 추가로 포함하는 광학 필름.The optical film of claim 1, further comprising a base layer formed on one surface of the liquid crystal layer.
- 제 1 항의 광학 필름; 및 상기 광학 필름의 일측에 배치되어 있는 위상차 필름을 포함하는 광학 적층체.Claim 1 optical film; And a retardation film disposed on one side of the optical film.
- 제 9 항에 있어서, 위상차 필름의 지상축과 상기 광학 필름의 액정층에서 상기 위상차 필름과 가장 인접하여 위치된 네마틱 액정 화합물의 광축이 이루는 각도가 5도 내지 90도의 범위 내에 있는 광학 적층체.The optical laminate according to claim 9, wherein an angle formed by the slow axis of the retardation film and the optical axis of the nematic liquid crystal compound positioned nearest to the retardation film in the liquid crystal layer of the optical film is within a range of 5 degrees to 90 degrees.
- 제 9 항에 있어서, 편광층을 추가로 포함하는 광학 적층체.10. The optical laminate of claim 9, further comprising a polarizing layer.
- 제 9 항에 있어서, 편광층, 위상차 필름 및 광학 필름을 순차 포함하고, 상기 편광층의 광 흡수축과 상기 위상차 필름의 지상축이 이루는 각도가 10도 내지 20도의 범위 내에 있으며, 상기 위상차 필름의 지상축과 상기 광학 필름의 액정층에서 상기 위상차 필름과 가장 인접하여 위치한 네마틱 액정 화합물의 광축이 이루는 각도가 8도 내지 16도의 범위 내에 있는 광학 적층체.10. The method of claim 9, wherein the polarizing layer, a retardation film and an optical film are sequentially included, the angle between the light absorption axis of the polarizing layer and the slow axis of the retardation film is in the range of 10 to 20 degrees, The optical laminated body in which the angle which the slow axis and the optical axis of the nematic liquid crystal compound located most adjacent to the said retardation film in the liquid crystal layer of the said optical film make is within the range of 8 degree | times to 16 degree | times.
- 제 12 항에 있어서, 액정층의 비틀림 각도가 36도 내지 50도의 범위 내에 있는 광학 적층체.The optical laminate according to claim 12, wherein the twist angle of the liquid crystal layer is in a range of 36 degrees to 50 degrees.
- 제 9 항에 있어서, 편광층, 위상차 필름 및 광학 필름을 순차 포함하고, 상기에서 위상차 필름의 지상축과 편광층의 광 흡수축은 수직하며, 상기 광학 필름의 액정층에서 상기 위상차 필름에 가장 가까운 액정 화합물의 광축이 상기 위상차 필름의 지상축과 이루는 각도는 50도 내지 70도의 범위 내에 있는 광학 적층체.10. The liquid crystal of claim 9, further comprising a polarizing layer, a retardation film, and an optical film, wherein the slow axis of the retardation film and the light absorption axis of the polarizing layer are perpendicular to each other and closest to the retardation film in the liquid crystal layer of the optical film. An optical laminated body in which the angle of the optical axis of the compound and the slow axis of the retardation film is in the range of 50 degrees to 70 degrees.
- 제 14 항에 있어서, 액정층의 비틀림 각도는 10도 내지 30도의 범위 내에 있는 광학 적층체.15. The optical laminate of claim 14, wherein the twist angle of the liquid crystal layer is in the range of 10 degrees to 30 degrees.
- 제 9 항에 있어서, 편광층, 위상차 필름 및 광학 필름을 순차 포함하고, 상기에서 위상차 필름의 지상축과 편광층의 광 흡수축은 수평이며, 상기 광학 필름의 액정층에서 상기 위상차 필름에 가장 가까운 액정 화합물의 광축이 상기 위상차 필름의 지상축과 이루는 각도는 15도 내지 35도의 범위 내에 있는 광학 적층체.10. The liquid crystal of claim 9, comprising a polarizing layer, a retardation film, and an optical film sequentially, wherein the slow axis of the retardation film and the light absorption axis of the polarizing layer are horizontal, and the liquid crystal layer closest to the retardation film in the liquid crystal layer of the optical film. An optical laminated body in which the angle of the optical axis of the compound and the slow axis of the retardation film is in the range of 15 degrees to 35 degrees.
- 제 16 항에 있어서, 액정층의 비틀림 각도는 60도 내지 85도의 범위 내에 있는 광학 적층체.17. The optical laminate of claim 16, wherein the twist angle of the liquid crystal layer is in the range of 60 degrees to 85 degrees.
- 네마틱 액정 화합물, 키랄제 및 중합 개시제를 포함하는 액정 코팅층에 상기 키랄제의 코팅층 두께에 따른 농도 변화를 유도하는 단계 및 상기 키랄제의 농도 변화가 유발된 상태에서 상기 네마틱 액정 화합물을 중합시키는 단계를 포함하는 제 1 항의 광학 필름의 제조 방법.Inducing a concentration change according to the thickness of the coating layer of the chiral agent to the liquid crystal coating layer including a nematic liquid crystal compound, a chiral agent and a polymerization initiator, and polymerizing the nematic liquid crystal compound in a state where the concentration change of the chiral agent is induced. Method for producing the optical film of claim 1, comprising the step.
- 제 18 항에 있어서, 농도 변화의 유도 및 액정 화합물의 중합 단계는 자외선 A 영역의 자외선을 40℃ 내지 80℃의 온도에서 10 mJ/cm2 내지 500 mJ/cm2의 광량으로 액정 코팅층에 조사하는 과정 및 자외선을 0.5 J/cm2 내지 10 J/cm2의 광량으로 키랄제의 농도 변화가 있는 액정 코팅층에 조사하는 과정을 포함하는 광학 필름의 제조 방법.19. The liquid crystal coating layer of claim 18, wherein the step of inducing a concentration change and polymerizing the liquid crystal compound comprises irradiating the ultraviolet light in the ultraviolet region A to the liquid crystal coating layer at an amount of 10 mJ / cm 2 to 500 mJ / cm 2 at a temperature of 40 ° C to 80 ° C. Process and the manufacturing method of an optical film including irradiating an ultraviolet-ray to the liquid-crystal coating layer with a change of density of a chiral agent by the light quantity of 0.5 J / cm <2> -10 J / cm <2> .
- 제 1 항의 광학 필름 또는 제 9 항의 광학 적층체를 포함하는 디스플레이 장치.A display device comprising the optical film of claim 1 or the optical laminate of claim 9.
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JP2008309957A (en) * | 2007-06-13 | 2008-12-25 | Nippon Oil Corp | Transmission type liquid crystal display device |
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