KR101560032B1 - Liquid Crystal Cell - Google Patents

Abstract

The present application relates to a liquid crystal cell, a method of manufacturing the liquid crystal cell, and a use of the liquid crystal cell. The exemplary liquid crystal cell of the present application can be manufactured simply and continuously through, for example, a roll-to-roll process. The liquid crystal cell can also be realized as a flexible element, and an excellent contrast ratio can be ensured. 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

A liquid crystal cell {Liquid Crystal Cell}

The present application relates to a liquid crystal cell, a method of manufacturing the liquid crystal cell, and a use of the liquid crystal cell.

An LCD (Liquid Crystal Display) realizes an image by orienting a nematic or smectic liquid crystal compound in a certain direction and switching the orientation through application of a voltage. Since LCD manufacturing process is a high-cost process requiring complex processes, large-scale production lines and facilities are required.

Among the proposed methods for solving the problem of the LCD manufacturing process, there is a so-called Polymer Dispersed Liquid Crystal (PDLC) which is implemented by dispersing a liquid crystal in a polymer matrix. Herein, the term PDLC is called Polymer Network Liquid Crystal (PNLC) or Polymer Stabilized Liquid Crystal ), Etc. The device is known. Since the PDLC can be manufactured through the coating of the liquid crystal solution, it can be manufactured by a simple process compared to the conventional LCD.

In the PDLC, the liquid crystal compound usually exists in an unorganized state. Therefore, the PDLC is in a hazy opaque state when no voltage is applied. When a voltage is applied to the PDLC, the liquid crystal compound is aligned and becomes transparent, and transparent and opaque states can be switched using the PDLC. However, the PDLC has a contrast ratio significantly lower than that of a conventional LCD in which black and white are switched between two polarizing plates.

The present application provides a liquid crystal cell, a method of manufacturing the liquid crystal cell, and a use of the liquid crystal cell.

Exemplary liquid crystal cells include an orientation layer and a liquid crystal layer. In the above, the liquid crystal layer may be disposed adjacent to the alignment layer, for example, on one side of the alignment layer. The liquid crystal layer may include a polymer network and a liquid crystal region. The liquid crystal region includes a liquid crystal compound and may be contained inside the polymer network. Figure 1 shows an alignment layer 101 and a liquid crystal layer 102 formed on one surface of the alignment layer 101. The liquid crystal layer 102 includes a polymer network 1021 and a liquid crystal region 1022, Cell. In Fig. 1, liquid crystal compounds in the liquid crystal region 1022 are indicated by arrows.

As the alignment layer in the liquid crystal cell, for example, an alignment layer containing a photo-aligning compound can be used. 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 orientation layer may exist in an aligned state so as to have a directivity. The photo aligning compound may be a monomolecular compound, a monomeric compound, an oligomeric compound or a polymeric compound.

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.

The photo aligning compound may be a monomolecular compound, a monomeric compound, an oligomeric compound, a polymeric compound, or a blend of the photo-aligning 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 layer may further contain a reactive compound, for example, a compound having at least one functional group capable of reacting with the photo-alignable 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 contained in the orientation layer 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 include 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, the adhesive force and orientation with the base layer or the polymer network can be maintained excellent.

The precursor forming the orientation layer 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 photoinitiators include alpha-hydroxy ketone compounds, alpha-amino ketone compounds, phenylglyoxylate compounds and oxime ester compounds, 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.

The liquid crystal layer may include a polymer network and a liquid crystal region. 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 polymer network may be, for example, a network of precursors comprising polymeric liquid crystal compounds. The term " network of precursors comprising polymerizable liquid crystal compounds " can refer, for example, to a polymer network comprising polymeric liquid crystalline compounds crosslinked or polymerized.

The term " polymerizable liquid crystal compound " may mean a compound containing a moiety capable of exhibiting liquid crystallinity, such as a mesogen skeleton, and further containing at least one polymerizable functional group. Further, the polymerizable liquid crystal compound may be polymerized to form a skeleton such as a main chain or a side chain of the liquid crystal polymer in the polymer network.

The polymerizable liquid crystal compound may be a polyfunctional polymerizable liquid crystal compound, a monofunctional polymerizable liquid crystal compound, or a mixture thereof. The term " polyfunctional polymerizable liquid crystal compound " means a compound having two or more, two to ten, two to eight, two to six, two to five, two or more polymerizable functional groups in the liquid crystal compound 4, 2, 3 or 2, and the term " monofunctional polymerizable liquid crystal compound " may mean a compound containing one polymerizable functional group in the liquid crystal compound.

The polymerizable liquid crystal compound may be, for example, a compound represented by the following formula (1).

[Chemical Formula 1]

Wherein A is a single bond, -COO- or -OCO-, and R ₁ to R ₁₀ are each independently selected from the group consisting of hydrogen, a halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, or a substituent of the formula 2, R ₁ to R ₅ pair of two adjacent substituents of R ₆ to R ₁₀ or a pair of two substituents adjoining are connected to each other but form a benzene substituted with -OQP, R ₁ to at least one of R ₁₀ may be a substituent of the formula -OQP or 2, R ₁ to R _5, or two substituents R ₆ to R _10, at least one pair of the two adjacent substituents of the adjoining are connected to each other -OQP Wherein Q represents an alkylene group or an alkylidene group, and P represents an alkenyl group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, or methacryloyl group Is a polymerizable functional group such as a silane group.

(2)

And R ₁₁ to R ₁₅ are each independently hydrogen, a halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group or -OQP, The pair of adjacent two substituents R ₁₁ to R ₁₅ are connected to each other to form benzene substituted with -OQP, wherein at least one of R ₁₁ to R ₁₅ is -OQP, or two adjacent R ₁₁ to R ₁₅ P is an alkylene group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group, a methacryloyl group, or a methacryloyl group. A diacrylate group, a acryloyloxy group or a methacryloyloxy group.

The fact that two adjacent substituents in the formulas (1) and (2) are connected to each other to form benzene substituted with -OQP means that two adjacent substituents are connected to each other to form a naphthalene skeleton substituted with -OQP as a whole .

In the formula (2), " - " on the left side of B may mean that B is directly bonded to benzene of the formula (1).

In the formulas (1) and (2), the term " single bond " means a case where no separate atom is present in a portion represented by A or B; For example, when A is a single bond in formula (I), benzene on both sides of A may be directly connected to form a biphenyl structure.

Examples of the halogen in the formulas (1) and (2) include, for example, chlorine, bromine, iodine and the like.

The term "alkyl group" means, for example, a straight chain 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 unless otherwise specified Or a cycloalkyl group having 3 to 20 carbon atoms, 3 to 16 carbon atoms, or 4 to 12 carbon atoms, for example. The alkyl group may be optionally substituted with one or more substituents.

The term "alkoxy group" may mean, for example, 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 unless otherwise specified. The alkoxy group may be linear, branched or cyclic. In addition, the alkoxy group may be optionally substituted with one or more substituents.

The term "alkylene group" or "alkylidene group" may mean, for example, an alkylene group or an alkylidene group having 1 to 12 carbon atoms, 4 to 10 carbon atoms, or 6 to 9 carbon atoms unless otherwise specified. The alkylene group or alkylidene group may be, for example, straight-chain, branched-chain or cyclic. In addition, the alkylene group or the alkylidene group may be optionally substituted with one or more substituents.

The term "alkenyl group" may mean, for example, an alkenyl group 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 unless otherwise specified . The alkenyl group may be, for example, linear, branched or cyclic. In addition, the alkenyl group may be optionally substituted with one or more substituents.

In the general formulas (1) and (2), P may be, for example, an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group, an acryloyloxy group or a methacryloyloxy group, Acryloyloxy group.

Examples of the substituent which may be substituted in the specific functional group in the present invention include alkyl groups, alkoxy groups, alkenyl groups, epoxy groups, oxo groups, oxetanyl groups, thiol groups, cyano groups, carboxyl groups, acryloyl groups, methacryloyl groups, Acryloyloxy group, methacryloyloxy group, aryl group, and the like, but the present invention is not limited thereto.

The -OQP, which may be present in at least one of the formulas (1) and (2) or the moiety of the formula (2), may for example be present at the position of R ₃ , R ₈ or R ₁₃ . Further, the substituents constituting benzene substituted with -OQP and connected to each other may be, for example, R ₃ and R ₄ , or R ₁₂ and R ₁₃ . The substituent other than -OQP or the residue of the formula (2) in the above-mentioned compound of formula (1) or the residue of formula (2) or substituents other than the substituent which is bonded to each other to form benzene may be, for example, hydrogen, halogen, A branched alkyl group, an alkoxycarbonyl group containing a straight or branched alkoxy group having 1 to 4 carbon atoms, a cycloalkyl group having 4 to 12 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group or a nitro group, and in another example Chlorine, a straight or branched alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 4 to 12 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group containing a straight-chain or branched alkoxy group having 1 to 4 carbon atoms, .

The precursors of the polymer network may include additives such as solvents, radicals or cationic initiators capable of inducing polymerization of the polymerizable liquid crystal compounds, basic substances, other reactive compounds capable of forming a network, or surfactants, if necessary As shown in FIG.

The polymer network can satisfy Equation 1 together with the liquid crystal compound in the liquid crystal region.

[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 ordinary refractive index of the liquid crystal compound, n _e is the extraordinary refractive index of the liquid crystal compound, and a is 0 < a < 0.5 Lt; / RTI &gt;

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 example, a nematic liquid crystal compound can be used as the liquid crystal compound. As such a 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 Formula 2, n _o is the ordinary refractive index of the liquid crystal compound defined in Equation 1, for example, the refractive index in the uniaxial direction of the nematic liquid crystal compound, and n _e is the refractive index of the liquid crystal compound defined in Formula 1 (extraordinary refractive index of the nematic liquid crystal compound in the major axis direction, 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.

The liquid crystal compound may also have a difference in dielectric constant (epsilon _e , extraordinary dielectric anisotropy, dielectric constant in the major axis direction) and normal dielectric constant (? _O , ordinary dielectric anisotropy have. 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.

The proportion of the polymer network in the liquid crystal layer is in the range of 0.5 to 200 parts by weight, 0.5 to 150 parts by weight, 0.5 to 100 parts by weight, 1 to 100 parts by weight based on 100 parts by weight of the liquid crystal compound in the liquid crystal region, 5 to 100 parts by weight, 5 to 80 parts by weight, 5 to 60 parts by weight, or 5 to 40 parts by weight. The ratio can be changed as needed.

The polymerizable liquid crystal compound forming the polymer network in the liquid crystal layer and / or the liquid crystal compound in the liquid crystal region may exist in an aligned state by the alignment layer. 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.

The liquid crystal cell may further include one or two or more base layers. The liquid crystal layer and the orientation layer may be formed on the surface of the base layer or between two or more base layers. For example, the liquid crystal cell may further include a base layer opposed to each other, and the liquid crystal layer and the orientation layer may be present between the opposed base layers. 2 shows an exemplary liquid crystal cell in which the alignment layer 101 and the liquid crystal layer 102 are present between the base layers 201A and 201B which are spaced apart from each other and spaced apart from each other at a predetermined interval.

As the substrate layer, known materials can be used 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 base layer, an optically isotropic base layer, a optically anisotropic base layer such as a retardation layer, a polarizing plate, a color filter substrate, or the like can be used.

Examples of the plastic substrate layer include 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) (PPS), polyarylate (PAR), amorphous fluororesin or the like can be used as the base layer, but it is possible to use a base layer containing at least one selected from the group consisting of PPS (polyphenylsulfone), PEI (polyetherimide), PEN (polyethylenemaphthatate) 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 base layer.

An electrode layer is included on the surface of the substrate layer, for example, on the surface of the substrate layer side (for example, the substrate layer 201A or 201B in contact with the orientation layer 101 or the liquid crystal layer 102 in Fig. 2) The electrode layer may 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), etc. 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 layer may be appropriately patterned It is possible.

The liquid crystal cell may further include a polarizing plate disposed on one side or both sides of the liquid crystal layer. 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 relates to a method of manufacturing a liquid crystal cell. Exemplary methods for producing a liquid crystal cell can include, for example, irradiating light onto a layer of a precursor of a liquid crystal layer formed on an alignment layer. By irradiating the layer of the precursor with light, for example, the polymeric liquid crystal compound is polymerized to form a polymer network, and the liquid crystal region can be formed by phase separation with the polymer network of the liquid crystal compound.

The alignment layer can be formed, for example, by aligning an aligning layer precursor containing the photo aligning compound on a suitable substrate, for example, the substrate layer, and aligning the photo aligning compound. 3 schematically shows a process of forming an alignment layer 101 by irradiating light onto a precursor of an alignment layer formed in the base layer 201A.

The precursor of the alignment layer 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 layer of the precursor of the orientation 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. On the surface of the base layer on which the precursor layer is formed, for example, the above-described transparent electrode layer may be formed.

After forming the layer of the precursor, the layer may 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.

After formation of the orientation layer, a layer of the precursor of the liquid crystal layer can be formed adjacent to the orientation layer. 4 schematically shows a process of forming a liquid crystal layer 102 by irradiating light to a precursor of a liquid crystal layer existing on the surface of the alignment layer 101 formed in FIG.

The precursor of the liquid crystal layer can be produced, for example, by dissolving the above-described polymerizable liquid crystal compound, a liquid crystal compound in which a liquid crystal region is formed, and other necessary additives (for example, an initiator) in a suitable solvent. As the solvent, it is possible to use a known solvent such as toluene, xylene, cyclopentanone or cyclohexanone. The precursor of the liquid crystal layer may be, for example, 1 to 60 parts by weight of the polymerizable liquid crystal compound and 40 to 100 parts by weight of the liquid crystal compound or 5 to 50 parts by weight of the polymerizable liquid crystal compound and 5 parts by weight of the liquid crystal compound To 95 parts by weight, but this can be changed if necessary.

After forming the layer of the precursor, the layer may be irradiated with light. Polymer networks and liquid crystal regions can be formed through irradiation of light. For example, in the case where the precursor of the liquid crystal layer contains a solvent or the like, the irradiation of the light can be performed after the formed layer is dried under appropriate conditions and the solvent is volatilized. Irradiation of light can also be performed in a state in which the liquid crystal compound is oriented by an adjacent alignment layer. The orientation of the dry and / or liquid crystal compounds can be performed, for example, by maintaining the layer of the precursor at a temperature of about 80 ° C to 130 ° C for about 1 minute to 10 minutes, but is not limited thereto.

The condition of light irradiation is not particularly limited as long as the polymerizable liquid crystal compound is polymerized to form a polymer network and the liquid crystal compound is phase-separated to form a liquid crystal region. Through the irradiation of light, the polymerizable liquid crystal compound is polymerized in the state of being oriented by the orientation layer to form a polymer network, and a liquid crystal region containing a liquid crystal compound can be formed in the polymer network. If necessary, an appropriate heat application or exposure process may be performed before or after the irradiation process of the light, or at the same time, in order to further promote the formation of the polymer network and the like.

An element having a structure shown in FIG. 2 may be formed by attaching a substrate layer having a transparent electrode layer formed on its surface, for example, to a liquid crystal layer formed when necessary after forming the liquid crystal layer through the above process .

The manufacturing process of the liquid crystal cell can be continuously performed by, for example, a roll-to-roll method.

The present application also relates to the use of a liquid crystal cell. Exemplary liquid crystal cells can be manufactured simply and continuously through, for example, a roll-to-roll process. The liquid crystal cell can also 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.

The exemplary liquid crystal cell of the present application can be manufactured simply and continuously through, for example, a roll-to-roll process. The liquid crystal cell can also be realized as a flexible element, and an excellent contrast ratio can be ensured. 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.

Figures 1 and 2 show an exemplary liquid crystal cell.
Figs. 3 and 4 are views for explaining a manufacturing process of an exemplary liquid crystal cell.
5 is a photograph showing the change in luminance between two polarizers of the liquid crystal cell manufactured in the example.
Fig. 6 is a graph showing the contrast ratio of the liquid crystal cell manufactured in the embodiment.

Hereinafter, the liquid crystal cell will be described in detail with reference to the embodiments of the present application, but the scope of the liquid crystal cell is not limited by the following embodiments.

Example

The orientation layer  formation

A mixture of a polynorbornene compound having a repeating unit represented by the following formula (PNBCi, weight average molecular weight 85,000, PDI (polydispersity index): about 4.75), acrylic monomer and photoacid generator (polynorbornene: acrylic monomer : Photoinitiator = 2: 1: 0.25 (weight ratio)) was dissolved in a toluene solvent so that the solids concentration of the polynorbornene was 2 wt% to prepare an alignment layer precursor. The precursor was coated on a transparent electrode layer of a transparent polycarbonate substrate layer having an ITO transparent electrode layer formed on its surface, irradiated with linearly polarized ultraviolet rays (1,200 mJ / cm ² ) via a WGP (Wire Grid Polarizer) .

(3)

The liquid crystal cell  Produce

(ZGS-8017, JNC, extraordinary refractive index: about 1.597, normal refractive index: about 1.487) for forming a liquid crystal region at a weight ratio of 1: 1 were mixed with the polymerizable liquid crystal compound of the following formula Was dissolved in a toluene solvent together with an initiator to prepare a liquid crystal layer precursor. Thereafter, the precursor of the liquid crystal layer was coated on the surface of the prepared alignment layer. After the coating, the layer of the precursor of the liquid crystal layer was maintained at a temperature of about 110 for about 5 minutes, followed by irradiation with ultraviolet light (300 mW / cm ² ) to form a polymer network and a liquid crystal region. The refractive index of the polymer network thus formed was measured by a prism coupler to be about 1.563. Thereafter, the surface of the ITO transparent electrode layer of the polycarbonate film having the ITO transparent electrode layer formed on its surface was attached to the liquid crystal layer formed to produce a liquid crystal cell.

[Chemical Formula 4]

Test Example  One.

The liquid crystal cells prepared in the examples were placed between two polarizing plates (upper and lower polarizing plates) arranged so that their light absorption axes were orthogonal to each other. The brightness was evaluated by irradiating light to the lower polarizer side in a state in which the alignment direction of the liquid crystal of the liquid crystal cell was arranged at 45 degrees or 90 degrees with the light transmission axis of the upper polarizer. FIG. 5 is a photograph showing the evaluation result, and the left side of FIG. 5 shows a case of forming 45 degrees with respect to the light transmission axis, and the right side of FIG. 5 shows a case of 90 degrees.

Test Example  2.

The liquid crystal cells prepared in the examples were placed between two polarizing plates (upper and lower polarizing plates) arranged so that their light absorption axes were orthogonal to each other. The alignment direction of the liquid crystal cell was arranged at 45 degrees with the light transmission axis of one of the two polarizers. Next, an AC power source was connected to the ITO transparent electrode layer of the upper and lower substrate layers (polycarbonate film), and the transmittance according to the driving voltage was measured with a photodiode laser, as shown in FIG. In Fig. 6, the X-axis represents the drive voltage and the Y-axis represents the transmittance. As can be seen in FIG. 6, the liquid crystal cell of the embodiment exhibited a contrast ratio of about 100: 1 at a voltage of about 76 V.

Test Example  3.

The transmission rate-voltage graph measured in Test Example 2 was analyzed with an oscilloscope and the response time was measured. The rising time was about 0.1 msec and the falling time was about 0.8 msec.

Test Example  4.

The transmittance and haze of the liquid crystal cell prepared in the examples were measured using a haze meter, and as a result, the transmittance was about 87.4% and the haze was about 1.81%.

101: orientation layer
102: liquid crystal layer
1021: Polymer networks
1022: liquid crystal region
201A, 201B: substrate layer

Claims (18)

An orientation layer; And a liquid crystal cell disposed adjacent to the alignment layer, the liquid crystal cell having a polymer network and a liquid crystal region existing in the network, the liquid crystal cell including a liquid crystal compound, wherein the polymer network and the liquid crystal compound satisfy the following formula:
[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
In Equation 1, 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 < The liquid crystal cell according to claim 1, wherein the alignment layer comprises a photo-aligning compound aligned to be oriented. The photosensitive resin composition according to claim 2, wherein the photo-orientable compound is at least one selected from the group consisting of an azo compound, a stilbene compound, a cyclobutane tetracarboxylic acid dianhydride, an aromatic polysilane, an aromatic polyester, a polystyrene, a cinnamate compound, a coumarin compound, a cinnamamide compound, a tetrahydrophthalimide (Meth) acrylate compound, or a spiropyran compound, wherein the liquid crystal compound is at least one compound selected from the group consisting of a benzoquinone compound, a maleimide compound, a benzophenone compound, a diphenylacetylene compound, a chalcone compound, an anthracenyl compound, a benzoate compound, a benzoamide compound, The liquid crystal cell of claim 1, wherein the polymer network is a network of precursors comprising a polymerizable liquid crystal compound. The liquid crystal cell according to claim 4, wherein the polymerizable liquid crystal compound is represented by the following formula (1):
[Chemical Formula 1]

Wherein A is a single bond, -COO- or -OCO-, and R ₁ to R ₁₀ are each independently selected from the group consisting of hydrogen, a halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group, -OQP or to a substituent of the formula 2, R ₁ to R ₅ pair of two adjacent substituents of R ₆ to R ₁₀ or a pair of two substituents adjoining are connected to each other but form a benzene substituted with -OQP, R ₁ to at least one of R ₁₀ it may be a substituent of the formula -OQP or 2, R ₁ to R _5, or two substituents R ₆ to R _10, at least one pair of the two adjacent substituents of the adjoining are connected to each other - OQP, wherein Q is an alkylene group or an alkylidene group, P is an alkenyl group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group or a meta Lt; / RTI &gt;
(2)

Wherein B is a single bond, -COO- or -OCO-, and R ₁₁ to R ₁₅ are each independently selected from the group consisting of hydrogen, a halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group or -OQP , A pair of two adjacent substituents of R ₁ to R ₅ or a pair of two adjacent substituents of R ₆ to R ₁₀ are connected to each other to form a benzene substituted with -OQP wherein at least one of R ₁₁ to R ₁₅ Is -OQP, or two adjacent substituents of R ₁₁ to R ₁₅ are connected to each other to form benzene substituted with -OQP, wherein Q is an alkylene group or an alkylidene group, P is an alkenyl group, An epoxy group, a cyano group, a carboxyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group. delete The liquid crystal cell according to claim 1, wherein the polymer network has a dielectric constant of 3 or more. The liquid crystal cell according to claim 1, wherein the liquid crystal compound is a nematic liquid crystal compound satisfying Formula 2:
[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. The method of claim 1, wherein at least the dielectric constant (ε _e) and the normal dielectric constant (ε _o) the difference (ε -ε _{e o)} of 3 or more liquid crystal cells of the liquid crystal compound. The liquid crystal cell according to claim 4, wherein the polymerizable liquid crystal compound or the liquid crystal compound in the liquid crystal region exists in an aligned state by the orientation layer. The liquid crystal cell according to claim 1, wherein the liquid crystal layer comprises 0.5 to 200 parts by weight of the polymer network relative to 100 parts by weight of the liquid crystal compound in the liquid crystal region. The liquid crystal cell according to claim 1, wherein the liquid crystal cell has a light transmittance of 80% or more in a state in which no voltage is applied. The liquid crystal cell according to claim 1, further comprising two base layers disposed opposite to each other, wherein a liquid crystal layer is formed between the base layers. 14. The liquid crystal cell according to claim 13, wherein an electrode layer is formed on the side of the liquid crystal layer of the substrate layer. The liquid crystal cell according to claim 1, further comprising a polarizing plate disposed on both sides of the liquid crystal layer. Comprising irradiating a precursor of a liquid crystal layer containing a precursor of a polymer network and a liquid crystal compound formed on an alignment layer with light, wherein the polymer network and the liquid crystal compound satisfy the following formula 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
In Equation 1, 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 < The method of manufacturing a liquid crystal cell according to claim 16, wherein the orientation layer is formed by irradiating linearly polarized light to a layer containing a photo-aligning compound. The method of manufacturing a liquid crystal cell according to claim 16, wherein the precursor comprises a polymerizable liquid crystal compound.

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