KR101987370B1 - Liquid crystal cell - Google Patents
Liquid crystal cell Download PDFInfo
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- KR101987370B1 KR101987370B1 KR1020150191037A KR20150191037A KR101987370B1 KR 101987370 B1 KR101987370 B1 KR 101987370B1 KR 1020150191037 A KR1020150191037 A KR 1020150191037A KR 20150191037 A KR20150191037 A KR 20150191037A KR 101987370 B1 KR101987370 B1 KR 101987370B1
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1339—Gaskets; Spacers; Sealing of cells
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1334—Constructional arrangements; Manufacturing methods based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133528—Polarisers
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
Abstract
The present application relates to a liquid crystal cell, a method of manufacturing a substrate for a liquid crystal cell, a method of manufacturing a liquid crystal cell, and a use of a liquid crystal cell. The exemplary liquid crystal cell of the present application can minimize the light leakage phenomenon and provide stable image quality by the spacer fixed to the substrate. The liquid crystal cell may also be embodied as a flexible element. Such a liquid crystal cell can be applied to various applications including, for example, a smart window, a window protective film, a flexible display device, an active retarder for 3D image display, or a viewing angle adjusting film.
Description
The present application relates to a liquid crystal cell, a method of manufacturing a substrate for a liquid crystal cell, a method of manufacturing a liquid crystal cell, and a use of a liquid crystal cell.
In a liquid crystal display (LCD), liquid crystal is placed between two substrates, that is, upper and lower substrates, and pixels are turned on by switching transistors for each pixel, so spacers are required between the substrates. The spacer spraying process according to the related art will be described as follows.
First, a transparent electrode pattern, an orientation film, and the like are formed on the upper or lower substrate, the substrate is mounted on a stage of a spacer application chamber, and a rectangular or cylindrical elastic material, for example, A spacer made of plastic, rubber, or the like is sprayed over the entire surface of the substrate. At this time, the spacers are adjusted to have a constant distribution ratio. Then, another substrate is bonded in an actual pattern, and a liquid crystal is injected and sealed.
In the method of applying a spacer of the LCD according to the related art as described above, there is a problem that the image quality is poor due to a difference in cell gap, the orientation of the liquid crystal in the pixel portion is deteriorated by the spacer, and the reliability of the process yield and device operation is inferior.
The present application provides a liquid crystal cell, a method of manufacturing a substrate for a liquid crystal cell, a method of manufacturing a liquid crystal cell, and a use of a liquid crystal cell.
The present application relates to a plasma display panel comprising first and second substrates arranged opposite to each other; A spacer fixed to the first or second substrate and spaced apart from the first and second substrates; And a liquid crystal layer interposed between the first and second substrates and an alignment layer existing on the first or second substrate.
The present application also provides a method of manufacturing a substrate for a liquid crystal cell, comprising fixing the spacer on a substrate using a precursor including a spacer and a curable composition, and forming an alignment film on the surface of the substrate.
The present application also provides a method of manufacturing a liquid crystal cell comprising forming a liquid crystal layer as a precursor containing a liquid crystal and a polymer precursor on a substrate produced according to the above, and laminating a second substrate on the liquid crystal layer.
The exemplary liquid crystal cell of the present application can minimize the light leakage phenomenon and provide stable image quality by the spacer fixed to the substrate. The liquid crystal cell may also be implemented as a flexible device. Such a liquid crystal cell can be applied to various applications including, for example, a smart window, a window protective film, a flexible display device, an active retarder for 3D image display, or a viewing angle adjusting film.
1 is a schematic view for explaining a manufacturing process of a liquid crystal cell as an example of the present invention.
Exemplary liquid crystal cells of the present application include first and second substrates disposed opposite each other, spacers secured to the first and / or second substrates to separate the first and second substrates, An alignment layer existing on the first and / or second substrate, and a liquid crystal layer existing between the first and second substrates.
In the present application, the term substrate is not limited to the first substrate or the second substrate unless it is explicitly referred to as a first substrate or a second substrate, and should be understood to mean a first substrate and a second substrate. That is, the term substrate refers to either the first substrate or the second substrate, or both.
In one embodiment, known materials can be used for the first and second substrates without any particular limitation. For example, inorganic films such as glass films, crystalline or amorphous silicon films, quartz or indium tin oxide (ITO) films, and plastic films can be used. As the substrate, a polarizing plate, a color filter substrate, or the like can also be used.
As the material of the plastic substrate, TAC (triacetyl cellulose); A cycloolefin copolymer (COP) such as a norbornene derivative; Poly (methyl methacrylate), PC (polycarbonate), polyethylene (PE), polypropylene (PVP), polyvinyl alcohol (PVA), diacetyl cellulose (DAC), polyacrylate (PAC), polyether sulfone (PES) But are not limited to, PPS (polyphenylsulfone), PEI (polyetherimide), PEN (polyethylenemaphthatate), PET (polyethyleneterephtalate), PI (polyimide), PSF (polysulfone), PAR (polyarylate) A coating layer of a silicon compound such as gold, silver, silicon dioxide or silicon monoxide, or a coating layer such as an antireflection layer may be present on the substrate if necessary.
An electrode layer may be included on the surface of the substrate, for example, on the surface of the substrate in contact with the liquid crystal layer side of the substrate. The electrode layer can be formed by, for example, depositing a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as ITO (Indium Tin Oxide). The electrode layer may be formed to have transparency. In this field, various materials and forming methods capable of forming a transparent electrode layer are known, and all of these methods can be applied. If necessary, the electrode layer formed on the surface of the substrate may be appropriately patterned.
In one embodiment, the spacer may be, but is not limited to, a ball spacer.
In one embodiment, the spacer may be secured to the first or second substrate by a photo-curing resin or a thermosetting resin. As such a curable resin, a (meth) acrylate compound, for example, a polyfunctional (meth) acrylate compound having a bifunctional or higher acrylate group or a methacrylate compound may be used. For example, there may be mentioned pentaerythritol triacrylate, tris (2-acrylolyloxyethyl) isocynurate, trimethylolpropane triacrylate, dipentaerythritol triacrylate, And dipentaerythritol hexaacrylate. Of these, two or more selected from these may be used together.
In one example, the spacer may comprise a coating layer comprising the photocurable resin or the thermosetting resin. The resin in the coating layer may be present in a crosslinked state. The spacer may be fixed to the first and / or second substrate by the coating layer.
In one embodiment, the thickness of the coating layer may be 0.1 to 0.5 times or 0.2 to 0.35 times the height of the spacer. The height of the spacer is a height of the spacer measured in the direction of shortest distance between the first substrate and the second substrate. The thickness of the coating layer may be a minimum thickness, a maximum thickness, or an average thickness of the coating layer existing on the surface of the spacer have. In this range, the spacers can be effectively fixed and the desired phase difference can be maintained. For example, the height of the spacer, which is intended for the phase difference development of 280 to 330 nm on the basis of the applied liquid crystal, may be about 3 to 5 mu m. In this case, the thickness of the coating layer is about 0.3 to 2.5 mu m or 1 to 2 mu m . Further, unless otherwise specified herein, the refractive index or phase difference is a value measured for a wavelength of about 550 nm.
In one embodiment, the alignment layer may be formed on the substrate and the spacer. The fact that the alignment film is formed on the substrate and the spacer in the present application means that the alignment film covers both the substrate and the spacer fixed to the substrate or the alignment film exists in a form covering both the substrate and the periphery of the spacer fixed to the substrate can do. The alignment film is formed to the peripheral portion of the spacer, thereby minimizing the light leakage due to the non-immobilized spacer. The shaded portion in Fig. 1 represents an alignment film and shows an alignment film formed on the substrate and the spacer fixed on the substrate.
In one embodiment, the alignment layer may comprise a photo-aligned compound aligned to be oriented. The term " photo-aligning compound " refers to a compound that is orientationally ordered through irradiation of light or the like, and aligns adjacent liquid crystal compounds in a predetermined direction through an interaction such as anisotropic interaction in the aligned state ≪ / RTI > The photo-orientable compound in the alignment film may exist in an aligned state so as to have a directivity.
The photo directing compound may be a compound containing a photosensitive moiety. Various photo-orientable compounds which can be used for the alignment of liquid crystal compounds are known. Photo-aligning compounds include, for example, compounds that are aligned by trans-cis photoisomerization; Compounds that are aligned by photo-destruction such as chain scission or photo-oxidation; Compounds that are aligned by photo-crosslinking or photopolymerization such as [2 + 2] cycloaddition, [4 + 4] addition cyclization or photodimerization; A compound aligned by photo-Fries rearrangement or a compound aligned by ring opening / closure reaction can be used. Examples of the compounds that are aligned by trans-cis photoisomerization include azo compounds such as sulfonated diazo dye or azo polymer, stilbenes, etc. Examples of the compound which is aligned by photolysis include cyclobutane-1,2,3,4-tetracarboxylic dianhydride, aromatic polysilane or polyester, polystyrene or polyimide, and the like. The compounds that are aligned by photo-crosslinking or photopolymerization include cinnamate compounds, coumarin compounds, cinnamamide compounds, tetrahydrophthalimide compounds, maleimide compounds, (Hereinafter, referred to as an anthracenyl compound) having a chalconyl residue (hereinafter, referred to as a chalcone compound) or an anthracenyl residue (hereinafter referred to as an anthracenyl compound) as a benzophenone compound or a diphenylacetylene compound or a photo- Examples of the compounds that can be aligned by optical freeze rearrangement include aromatic compounds such as benzoate compounds, benzoamide compounds, and methacrylamidoaryl methacrylate compounds, Examples of the compounds to be aligned by the ring-opening / ring closing reaction include spiropyran compounds and the like A [4 + 2] π- electron system ([4 + 2] π-electronic system), but may be exemplified by compounds such as sorting by a ring opening / ring-closure reaction of, without being limited thereto.
In one embodiment, the photo-orientable compound may be a monomolecular compound, a monomeric compound, an oligomeric compound, a polymeric compound, or a blend of the photo-orientable compound and the polymer. The oligomeric or macromolecular compound may have a residue derived from the above-described photo-orienting compound or a photo-sensitive residue described above in the main chain or side chain.
Examples of the polymer having a moiety or photosensitizing moiety derived from the photo-orienting compound or capable of being mixed with the photo-aligning compound include polynorbornene, polyolefin, polyarylate, polyacrylate, poly (meth) (Meth) acrylate, poly (amic acid), polymaleinimide, polyacrylamide, polymethacrylamide, polyvinyl ether, polyvinyl ester, polystyrene, polysiloxane, polyacrylonitrile or polymethacrylonitrile But is not limited thereto.
Examples of the polymer that can be contained in the oriented compound include polynorbornene cinnamate, polynorbornene alkoxy cinnamate, polynorbornene allyloyloxycinnamate, polynorbornene fluorinated cinnamate, polynorbornene chlorinated cinnamate, or Polynorbornene dicinnamate, and the like, but are not limited thereto.
When the oriented compound is a polymeric compound, the compound may have a number average molecular weight of, for example, from about 10,000 g / mol to about 500,000 g / mol, but is not limited thereto.
The alignment film may further include a reactive compound, for example, a compound having at least one functional group capable of reacting with the photo-aligning compound. The reactive compound may include, for example, 2 or more, 2 to 10, 4 to 10, or 4 to 8 functional groups. The functional group may have reactivity with a polymer network of the liquid crystal layer or a precursor for forming the network. The reactive compound may be, for example, a reaction in which a photo-orienting compound in the mixture is subjected to light orientation to form a liquid crystal layer in the process of irradiating light to form a liquid crystal layer, For example, it is possible to induce an additional reaction separate from the photo-crosslinking or photopolymerization reaction. Further, the average tilt angle of the liquid crystal molecules in the liquid crystal layer can be controlled by controlling the weight ratio of the reactive compound and the photo-aligning compound in the mixture.
Additional reactions may include crosslinking reactions between photo-orienting compounds, crosslinking reactions between photo-orienting compounds and reactive compounds or polymer networks and reactive compounds, and the like. Accordingly, the reactive compound may be included in the orientation film in a state of being reacted with a photo-orienting compound or a polymer network.
Examples of the functional group capable of reacting with the photo-aligning compound and / or the polymer network include a functional group capable of crosslinking with a photo-orienting compound and / or a polymer network by a free radical reaction, and a functional group containing an ethylenically unsaturated double bond Can be exemplified. Specific examples of the functional groups include an alkenyl group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group or a methacryloyl group, and the like.
The reactive compound may be a compound having one or more, two or more, two to ten, four to ten, or four to eight such functional groups and having a molecular weight or weight average molecular weight of 200 to 5,000 or 200 to 1,000 have. In the range of the number of such functional groups and the molecular weight or the weight average molecular weight, the compound can maintain the liquid crystal orientation of the photo-aligning compound while maintaining the additional reaction appropriately, thereby improving the durability of the liquid crystal cell.
Examples of the reactive compound include methyl (meth) acrylate, ethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate or 2- (2-oxo-imidazolidinyl) ethyl Alkyl (meth) acrylates such as methyl (meth) acrylate; Hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate or hydroxypropyl (meth) acrylate and the like; Alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate and the like; Carboxyalkyl (meth) acrylates such as carboxyethyl (meth) acrylate and the like; (Meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol penta (Meth) acrylate, pentaerythritol tri (meth) acrylate, triethylene glycol di (meth) acrylate, triethylene glycol di , 6-hexanediol di (meth) acrylate, glycerol di (meth) acrylate, tris [2- (acryloyloxy) ethyl] isocyanurate, urethane acrylate, glycerol 1,3-diglycerol di (Meth) acrylate or tri (propylene glycol) glycerolate diacrylate; Alkenyl (meth) acrylates such as vinyl (meth) acrylate or allyl (meth) acrylate; Alkoxypolyalkylene glycol (meth) acrylates such as butoxy triethylene glycol (meth) acrylate and the like; Acryloyloxyalkyl esters such as mono-2- (acryloyloxy) ethyl succinate and the like; (Meth) acryloyloxyalkyl (meth) acrylate such as 3- (acryloyloxy) -2-hydroxypropyl (meth) acrylate and the like; (Meth) acrylamide, diacetone (meth) acrylamide, N- [tris (hydroxymethyl) methyl] acrylamide, N, N- (1,2-dihydroxyethylene) (Meth) acrylamide or derivatives thereof such as (1,2-dihydroxyethylene) bisacrylamide or N, N-methylenebis (acrylamide); Acetamidoacrylic acid alkyl esters such as methyl 2-acetamidoacrylate and the like; (Meth) acryloyl groups such as 1,3,5-triacryloylhexahydro-1,3,5-triazine or 2,4,6-triallyloxy-1,3,5-triazine, Triazine substituted with a phenyl group; Isocyanurate substituted with an epoxy group such as tris (2,3-epoxypropyl) isocyanurate and the like; A carboxylate substituted with an alkenyl group such as tetracyanoethylene oxide, tetracyanoethylene oxide and tetracyanoethylene oxide, triallylbenzene tricarboxylate and the like; Caprolactone (meth) acryloyloxyalkyl esters such as caprolactone 2 - ((meth) acryloyloxy) ethyl ester and the like, maleic acid Methacryloyloxyalkyl ester, 1,2,3-triazole-4,5-dicarboxylic acid and the like, an alkenyl group such as 3-allyloxy-1,2-propanediol and the like (2-vinyl-1,3-dioxalane) alkane substituted with a glycidyloxyphenyl group such as an alkane diol, bis [4- (glycidyloxy) (Melamine-co-formaldehyde), and the like, but the present invention is not limited thereto. As used herein, the term (meth) acryl means acrylic or methacryl.
The alignment layer may contain the reactive compound in a proportion of, for example, 10 parts by weight to 1,000 parts by weight or 25 parts by weight to 400 parts by weight based on 100 parts by weight of the photo-aligning compound. At such a ratio, it is possible to maintain excellent adhesion and orientation to the substrate or the polymer network.
The precursor forming the orientation film may further comprise a photoinitiator in addition to the photo-orienting compound. The photoinitiator can be used without particular limitation, for example, as long as it can induce a free radical reaction by irradiation of light. Examples of such a photoinitiator include an? -Hydroxyketone compound,? -Amino ketone compound, phenylglyoxylate compound or oxime ester compound, and oxime ester compounds can be used, for example. The proportion of the photoinitiator in the precursor is not particularly limited and may be included so as to induce a proper reaction.
In one embodiment, the liquid crystal layer may comprise a polymer network and a liquid crystal region present within the network and comprising a liquid crystal compound. The term " liquid crystal region " may refer to a region containing a liquid crystal compound, which is dispersed in the network in a phase separated from the polymer network. The liquid crystal region includes a liquid crystal compound and may be contained inside the polymer network.
In one embodiment, the polymer network and the liquid crystal compound may be one that satisfies the following equation (1).
[Equation 1]
(1-a) × {( 2n o 2 + n e 2) / 3} 0.5 <n p <(1 + a) × {(2n o 2 + n e 2) / 3} 0.5
Where n p is the refractive index of the polymer network, n o is the normal refractive index of the liquid crystal compound, n e is the extraordinary refractive index of the liquid crystal compound, and a satisfies 0? A <0.5.
In the present specification, the refractive index may be a refractive index measured for light having a wavelength of 550 nm, for example. Also, when the normal refractive index and the extraordinary refractive index of the polymer network are different, the refractive index of the polymer network used in the present specification means the normal refractive index of the network. By selecting the polymer network and the liquid crystal compound to satisfy the above-mentioned formula 1, it is possible to provide an element excellent in transparency and excellent in contrast ratio under no voltage application.
In Formula 1, a may be, for example, less than 0.4, less than 0.3, less than 0.2 or less than 0.1, or zero.
The polymer network may also have a dielectric anisotropy of 3 or more, 3.5 or more, or 4 or more. The driving voltage characteristic of the liquid crystal cell can be kept excellent in such a range of the dielectric constant. The upper limit of the dielectric constant is not particularly limited and may be, for example, about 20 or less, about 15 or less, or about 10 or less.
The liquid crystal region dispersed in the polymer network includes a liquid crystal compound. As the liquid crystal compound, any kind of compound can be used as long as it is phase-separated in the polymer network and can exist in a state oriented by the polymer network. For example, as the liquid crystal compound, a smectic liquid crystal compound, a nematic liquid crystal compound, or a cholesteric liquid crystal compound can be used. The liquid crystal compound may be in a form that is phase-separated and not bonded to the polymer network, and the orientation can be changed accordingly when a voltage is applied from the outside. For this purpose, for example, the liquid crystal compound may be a compound having no polymerizable group or a crosslinkable group.
In one embodiment, the polymer network may have a dielectric constant of three or more.
In one embodiment, the liquid crystal compound may be a nematic liquid crystal compound as the liquid crystal compound. For example, a nematic liquid crystal compound satisfying the following formula 2 can be used.
[Equation 2]
(1.53 - b) <{( 2n o 2 + n e 2) / 3} 0.5 <(1.53 + b)
In the above formula (2), n o is the normal refractive index of the liquid crystal compound, n e is the extraordinary refractive index of the liquid crystal compound, and b is a number satisfying 0.1 ≦ b ≦ 1. A liquid crystal cell satisfying the formula 2 can be selected to manufacture a liquid crystal cell that secures excellent transparency even when no voltage is applied.
In another embodiment, b may be 0.1 to 0.9, 0.1 to 0.7, 0.1 to 0.5, or 0.1 to 0.3.
In one embodiment, the difference (ε -ε e o) of at least a liquid crystal compound the dielectric constant (ε e, extraordinary dielectric anisotropy, the dielectric constant in the major axis direction) and the normal dielectric constant (ε o, ordinary dielectric anisotropy, the dielectric constant in the minor axis direction) 3 Or more. For example, the difference between the ideal permittivity and the normal permittivity may be 4 or more, 6 or more, 8 or more, or 10 or more. By providing such a dielectric constant, it is possible to provide a device having excellent driving voltage characteristics. The difference in the dielectric constant means that the higher the numerical value is, the more appropriate characteristics can be exhibited by the device, and the upper limit is not particularly limited. For example, the liquid crystal compound to not less than the dielectric constant (ε e, extraordinary dielectric anisotropy, the long axis direction of the dielectric constant), and the 6 to 50 degree, the normal dielectric constant (ε o, ordinary dielectric anisotropy, the dielectric constant in the minor axis direction) is 2.5 to 7 degree Phosphorus compounds can be used.
In one embodiment, the liquid crystal compound may be in an aligned state by an orientation film. Such a liquid crystal cell can exhibit excellent transparency even when a voltage is not applied, for example. For example, the liquid crystal cell may exhibit a light transmittance of 80% or more, 85% or more, 90% or more, or 95% or more in the voltage unapplied state. The light transmittance may be a light transmittance for a visible light region, for example, a wavelength in the range of about 400 nm to 700 nm.
In one embodiment, the liquid crystal cell may further comprise a polarizer disposed on a surface of the first or second substrate. As the polarizing plate, ordinary materials used in conventional LCDs can be used without any particular limitation. When the polarizing plates are arranged on both sides of the liquid crystal cell, for example, the light absorption axes of the respective polarizing plates may be arranged so as to be perpendicular to each other.
The present application also provides a method of manufacturing a substrate for a liquid crystal cell. An exemplary method of manufacturing a substrate for a liquid crystal cell can include fixing the spacer on a substrate using a precursor comprising a spacer and a curable composition, and forming an alignment film on a surface of the substrate. This is shown in the substrate for a liquid crystal cell or the first substrate portion in Fig. As the curable composition, a heat or photo-curable resin can be used, and the above-mentioned method is as described above. Methods for securing spacers according to the resin used are well known in the art. For example, in the case of the photo-curing resin composition, the ball spacer can be fixed on the substrate by irradiating ultraviolet rays and applying heat in the case of the thermosetting resin composition.
In one embodiment, the precursor may comprise from 0.5% to 2% by weight of the ball spacer.
In one embodiment, the precursor may be a solventless type. A solvent-free precursor means that the precursor does not include a solvent such as an organic solvent or an aqueous solvent. Since the precursor does not contain a solvent, it is possible to increase the process efficiency of manufacturing a substrate for a liquid crystal cell, and to manufacture a substrate for a uniform liquid crystal cell in which there is substantially no thickness variation. Further, by eliminating the solvent, it is possible to prevent generation of bubbles and leveling caused by the volatilization step of the solvent or the like. In addition, no solvent volatilization process is required, so that contamination is not caused during the process.
In one embodiment, the ball spacers can be fixed on the substrate, and the alignment film can be formed on the substrate on which the ball spacers are fixed. The alignment film can be formed by, for example, coating an alignment film precursor containing a photo-aligning compound on a substrate and aligning the photo-aligning compound. The precursor of the alignment film may contain an appropriate amount of the above-described reactive compound or initiator in addition to the photo-aligning compound, and may contain other additives such as a surfactant if necessary. The precursor layer of the alignment layer can be formed, for example, by coating the precursor with a conventional coating method such as bar coating, comma coating, ink jet coating, or spin coating.
After forming the precursor layer of the alignment film, the layer can be irradiated with light. For example, when the precursor includes a solvent or the like, irradiation with light may be performed after the formed layer is dried under appropriate conditions to volatilize the solvent. Such drying can be carried out, for example, at a temperature of about 60 DEG C to 130 DEG C for about 1 minute to 5 minutes, but is not limited thereto.
Irradiation of light can be performed so that the orienting compound contained in the layer of the precursor can be aligned. Alignment of the oriented compound is typically carried out using linearly polarized light. The wavelength or intensity of the light to be irradiated may be selected to provide for proper alignment of the orienting compound. Typically, the photo directing compound is aligned by light in the visible or near ultraviolet range, but light in the far ultraviolet or near infrared range may be used if necessary.
In one embodiment, the fixation of the spacer and the formation of the orientation film can be performed on the substrate on which the transparent electrode is formed.
The present application also relates to a method for manufacturing a liquid crystal cell comprising the steps of: forming a liquid crystal layer as a precursor containing a liquid crystal and a polymer precursor on a substrate for a liquid crystal cell manufactured according to the above-described method for manufacturing a substrate for a liquid crystal cell, A method of manufacturing a liquid crystal cell is provided. A precursor including a liquid crystal and a polymer precursor may be coated on a substrate to form a liquid crystal layer, and precursors including a liquid crystal and a polymer precursor are as described above. The second substrate can be made the same as the first substrate except that it does not contain spacers. For example, the second substrate can be manufactured by forming an alignment film on the surface of the substrate.
In one embodiment, it is further possible to form a sealant on the edge of the substrate or the substrate on which the ball spacers are fixed before the second substrate is laminated. The sealant is formed between the first substrate and the second substrate to seal the first substrate and the second substrate and seal the liquid crystal to prevent impurities from the outside from flowing into the liquid crystal cell. Methods of forming the sealant are well known in the art. For example, a sealant can be formed by applying a sealant of a polymer mixture in which an epoxy resin and a curing accelerator are mixed to the rim of the first substrate or the second substrate. In one embodiment, the sealant may further comprise a spacer.
The present application also relates to the use of a liquid crystal cell. An exemplary liquid crystal cell can be realized as a flexible element, and an excellent contrast ratio can be secured.
Such a liquid crystal cell can be applied to various applications such as a smart window, a window protective film, a flexible display device, an active retarder for 3D image display, or a viewing angle adjusting film.
Claims (20)
Forming a liquid crystal layer from a liquid crystal precursor material including a liquid crystal and a polymer precursor on the first substrate on which the alignment layer is formed, and laminating a second substrate on the liquid crystal layer,
Wherein the spacer precursor comprises from 0.5% to 2% by weight of a ball spacer,
Wherein the spacer precursor material is a solventless type.
Wherein the curable composition forms a coating layer, and the spacer is fixed to the first or second substrate by the coating layer.
[Equation 1]
(1-a) × {( 2n o 2 + n e 2) / 3} 0.5 <n p <(1 + a) × {(2n o 2 + n e 2) / 3} 0.5
Where n p is the refractive index of the polymer network, n o is the normal refractive index of the liquid crystal compound, n e is the extraordinary refractive index of the liquid crystal compound, and a satisfies 0? A <0.5.
[Equation 2]
(1.53 - b) <{( 2n o 2 + n e 2) / 3} 0.5 <(1.53 + b)
In the above formula (2), n o is the normal refractive index of the liquid crystal compound, n e is the extraordinary refractive index of the liquid crystal compound, and b is a number satisfying 0.1 ≦ b ≦ 1.
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| JPH0987363A (en) * | 1995-09-25 | 1997-03-31 | Nippon Zeon Co Ltd | Photocurable composition, sealing material, method for sealing, and sealed liquid crystal |
| US6621548B2 (en) * | 2001-06-15 | 2003-09-16 | Viztec, Inc. | Electrooptical displays constructed with polymer-coated elements positioned between substrates |
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