KR101676100B1 - Liquid Crystal Film - Google Patents

Liquid Crystal Film Download PDF

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KR101676100B1
KR101676100B1 KR1020140129847A KR20140129847A KR101676100B1 KR 101676100 B1 KR101676100 B1 KR 101676100B1 KR 1020140129847 A KR1020140129847 A KR 1020140129847A KR 20140129847 A KR20140129847 A KR 20140129847A KR 101676100 B1 KR101676100 B1 KR 101676100B1
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liquid crystal
group
alignment
film
layer
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KR20150039101A (en
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이대희
장준원
김영진
박문수
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주식회사 엘지화학
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Abstract

The present application provides a liquid crystal film, a method for producing the liquid crystal film, and its use. An exemplary liquid crystal film can control the degree of photo-curing of an alignment film including an aligning material and a chiral agent to pattern the liquid crystal alignment of the liquid crystal layer formed on the alignment film. Such a liquid crystal film can be applied to, for example, a security device, a counterfeit or anti-fake device.

Description

[0001] Liquid crystal film [0002]

The present application relates to a liquid crystal film, a method for producing the liquid crystal film, and a use thereof.

Various types of authentication devices exist to prevent counterfeiting and duplication of bills, credit cards, securities, or identification cards. As such an authentication device, for example, an authentication device using a hologram, a cinegram, or the like based on the diffraction of light by gratings is mainly used. These diffractive optical elements need to be observed at different viewing angles to confirm their authenticity. That is, the diffractive optical elements produce a three-dimensional image or a color change effect according to an observation angle, and must be inspected based on predetermined criteria or rules. However, it is impossible to use a machine that reads such information as encoded images or numbers using such a technique. Moreover, the information content of these devices is very limited, and there is a limitation that only optical experts can clearly distinguish between counterfeit and authentic. In addition, since diffractive optical effects can be used over time, other than in the field of safety, for example, in consumer products such as wrapping paper, toys, etc., the way in which such devices are produced becomes known to a large number of people over time, There is a problem. Recently, as disclosed in Patent Document 1, there is an increasing interest in an authentication device using an anisotropic liquid crystal layer which is known to be suitable for optimal copy protection.

Korean Patent Laid-Open No. 2001-0012407

The present application provides a liquid crystal film, a method for producing the liquid crystal film, and its use.

An exemplary liquid crystal film may include an alignment film and a liquid crystal layer present in contact with the alignment film. The alignment film includes an aligning material and a chiral agent, and may have orientation in one direction. The liquid crystal layer may include first and second liquid crystal regions having different angles between the direction of the liquid crystal waveguide existing on the surface opposite to the alignment layer and the one direction. The direction of the liquid crystal waveguide in the present application may mean, for example, the major axis direction of the liquid crystal molecule. The angle of the first liquid crystal region may be, for example, in the range of -5 to 5 degrees, and the angle of the second liquid crystal region may be, for example, less than -5 degrees, or more than 5 degrees. FIG. 1 shows an alignment film 101 having an alignment in a direction (로) and a liquid crystal film 102 which is in contact with the alignment film and includes a liquid crystal layer 102 having first and second liquid crystal regions 1021 and 1022 ≪ / RTI >

The alignment film may be an aligning material, for example, a photo aligning material. In the present specification, the photo-alignment material means an optically-oriented compound that is orientationally ordered through irradiation of light, for example, and is capable of aligning an adjacent liquid crystal compound or the like in a predetermined direction in the aligned state . Such photo aligning compounds may be monomolecular compounds, monomeric compounds, oligomeric compounds or polymeric compounds.

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 allyloyloxy cinnamate, 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 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 an anion of light. Examples of such photoinitiators include alphahydroxyketone compounds, alpha amino ketone compounds, phenylglyoxylate compounds, and oxime ester compounds. The proportion of the photoinitiator in the precursor is not particularly limited and may be included to such an extent as to induce an appropriate reaction.

The chiral agent contained in the alignment layer can induce, for example, the arrangement of liquid crystal molecules to have a helical structure. The chiral agent may be used without particular limitation, so long as it does not impair liquid crystallinity, for example, nematic regularity, and can induce a desired helical structure. The chiral agent for causing the helical structure in the liquid crystal needs to include at least the chirality in the molecular structure. Chiral agents include, for example, a compound having one or more asymmetric carbons, a compound having an asymmetric point on a heteroatom such as a chiral amine or a chiral sulfoxide, or a compound having an asymmetric carbon atom such as cumulene ) Or binaphthol (axially asymmetric optically active site) having an axially reducing agent. The chiral agent may be, for example, a low molecular weight compound having a molecular weight of 1,500 or less. As the chiral agent, a commercially available chiral nematic liquid crystal, for example, a chiral dopant liquid crystal S-811 available from Merck Co., Ltd. or LC756 manufactured by BASF may be used.

The alignment layer may include first and second alignment regions respectively disposed under the first and second liquid crystal regions of the liquid crystal layer. 2 shows an alignment film including the first and second alignment regions 1011 and 1012 and a liquid crystal layer 102 which is in contact with the alignment film and includes the liquid crystal layer 102 having the first and second liquid crystal regions 1021 and 1022, The film is illustratively shown. The first and second alignment regions may exhibit different degrees of curing, and for example, the first alignment region may exhibit a relatively high degree of curing as compared to the second alignment region. In the present specification, the degree of curing of the orientation film may mean, for example, the degree to which the photo-orientable material is cured. In the case where alignment regions having different degrees of curing are formed in the alignment film, for example, as shown in Fig. 3, the chiral agent in the alignment region having a high degree of curing is present in the alignment film without being diffused into the upper liquid crystal layer, The chiral agent in the alignment region can diffuse into the upper liquid crystal layer to induce rotation of the liquid crystal compound.

Thus, the first and second liquid crystal regions of the liquid crystal layer formed on the first and second alignment regions may exhibit different liquid crystal alignment properties. For example, the first region may have an angle formed by a direction of the liquid crystal waveguide at a portion in contact with the alignment film and a direction of a liquid crystal waveguide at a surface opposite to the surface in contact with the alignment film within a range of -5 degrees to 5 degrees . In other words, since the chiral agent present in the alignment layer is not diffused in the first liquid crystal region, rotation of the liquid crystal compound is not induced, and liquid crystal alignment in a similar direction can be exhibited on the surface in contact with the alignment layer and on the surface opposite to the surface in contact with the alignment layer. On the other hand, in the second liquid crystal region, the angle formed by the direction of the liquid crystal waveguide in the portion in contact with the alignment film and the direction of the liquid crystal waveguide in the surface on the opposite side of the surface in contact with the alignment film is about 10 to 200 degrees It can be tomorrow. That is, since the chiral agent present in the alignment layer is diffused in the second liquid crystal region, rotation of the liquid crystal compound is induced, and a so-called twisted nematic (TN) liquid crystal alignment is effected at the surface opposite to the surface in contact with the alignment film, Lt; / RTI >

Such a liquid crystal layer may exhibit a quarter-wave phase retardation characteristic in the first or second liquid crystal region, for example. In the present specification, the "n-wavelength phase delay characteristic" may mean a characteristic that the incident light can be phase-delayed by n times the wavelength of the incident light within at least a part of the wavelength range. For example, the liquid crystal layer may have a phase retardation of from 110 nm to 220 nm or from 130 nm to 170 nm for a wavelength of 550 nm. In the specification, " plane phase difference " is a numerical value calculated by (nx-ny) xd, where nx is the refractive index in the surface phase axial direction of the liquid crystal layer, ny is the refractive index in the plane- Is the thickness of the liquid crystal layer. Further, in the present specification, the term "slow axis" may mean an axis indicating the highest refractive index in the liquid crystal layer, and "fast axis" means a direction indicating the lowest refractive index in the liquid crystal layer It can mean axis. Further, in the present specification, the term "optical axis" may mean a slow axis or a fast axis in the liquid crystal layer, and may mean, for example, a slow axis.

The second liquid crystal region may have, for example, a twisted nematic liquid crystal orientation. That is, in the second liquid crystal region, the liquid crystal compound may be twisted. Specifically, in the specification of the present application, the twisted orientation of a liquid crystal compound may mean a spiral alignment structure in which waveguides of liquid crystal molecules are twisted along a spiral axis to form a layer. Such a structure is similar to a so-called cholesteric orientation, but when the distance from the waveguide of the liquid crystal molecule to the completion of the rotation of 360 degrees is referred to as a pitch, the twisted nematic liquid crystal layer has a cholesteric And can be distinguished from orientation. That is, in the twisted nematic liquid crystal layer, the waveguide of the liquid crystal molecules may not be rotated 360 degrees.

The twist angle of the twisted nematic liquid crystal alignment of the second liquid crystal region may be, for example, in the range of 10 degrees to 200 degrees. In the present specification, the term "twist angle" refers to an angle formed by the direction of the waveguide of the nematic liquid crystal existing at the lowermost part of the twisted nematic liquid crystal layer and the direction of the waveguide of the nematic liquid crystal located at the uppermost part of the twisted nematic liquid crystal layer . ≪ / RTI >

The twisted nematic liquid crystal alignment of the two liquid crystal regions may be formed so that the helical axis of the waveguide of the liquid crystal is parallel to the thickness direction of the liquid crystal layer. The term " thickness direction of the liquid crystal layer " in the present specification may mean a direction parallel to an imaginary line connecting the one main surface of the liquid crystal layer and the main surface opposite thereto at the shortest distance.

The liquid crystal layer may include, for example, a polymerizable liquid crystal compound as a liquid crystal. In the present specification, the term "polymerizable liquid crystal compound" may mean a compound containing a moiety capable of exhibiting liquid crystallinity, such as a mesogen skeleton, and containing at least one polymerizable functional group. The polymerizable liquid crystal compound can be contained in the liquid crystal layer, for example, in a crosslinked or polymerized state. In the present specification, "the polymerizable liquid crystal compound is contained in a crosslinked or polymerized form" may mean a state in which the liquid crystal compound is polymerized to form a skeleton such as a main chain or side chain of the liquid crystal polymer in the liquid crystal layer have.

As the polymerizable liquid crystal compound, for example, a compound represented by the following formula (1) can be used.

[Chemical Formula 1]

Figure 112014092315065-pat00001

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 Wherein at least one of R 1 to R 10 is -OQP or a substituent of the following formula 2 or two adjacent substituents of R 1 to R 5 or two adjacent substituents of R 6 to R 10 are And 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 acryloyl group, A methoxy group, a methoxy group, a methoxy group, a methoxy group,

(2)

Figure 112014092315065-pat00002

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 , At least one of R 11 to R 15 is -OQP, or 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, and P is an alkenyl group, an epoxy group, a cyano group, A methacryloyl group, an acryloyloxy group, or a methacryloyloxy group.

The formation of benzene substituted with -OQP in the above two substituents in Formulas 1 and 2 means that two adjacent substituents are connected to each other to form a naphthalene skeleton substituted with -OQP as a whole have.

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

The term "single bond" in the above formulas (1) and (2) means a case where no separate atom exists in the part 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.

As the halogen in the above formulas (1) and (2), chlorine, bromine or iodine can be exemplified.

Unless otherwise specified, the term alkyl group in the present specification means a straight or branched 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, , A cycloalkyl group having 3 to 16 carbon atoms or 4 to 12 carbon atoms. The alkyl group may be optionally substituted with one or more substituents.

The term alkoxy group in the present specification may mean 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.

In the present specification, the term alkylene group or alkylidene group may mean 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 linear, branched or cyclic. Also, the alkylene group or alkylidene group may be optionally substituted with one or more substituents.

Unless otherwise specified, the alkenyl group in the present specification may mean 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. The alkenyl group may be 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 is preferably an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group, more preferably an acryloyloxy group or a methacryloyloxy group, And more preferably an acryloyloxy group.

Examples of the substituent which may be substituted in the specific functional group in the present specification include alkyl groups, alkoxy groups, alkenyl groups, epoxy groups, oxo groups, oxetanyl groups, thiol groups, cyano groups, carboxyl groups, acryloyl groups, , An acryloyloxy group, a methacryloyloxy group, or an aryl group, 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 . Further, substituents other than -OQP or the residue of the formula (2) or the residue of the formula (1) or the substituent other than the substituent which is connected to each other to form benzene may be, for example, hydrogen, halogen, a straight chain 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 polymerizable liquid crystal compound may be contained in the liquid crystal layer in a horizontally oriented state, for example. In the present specification, the term "horizontal alignment" means that the optical axis of the liquid crystal layer containing the polymerized liquid crystal compound is in the range of from about 0 degrees to about 25 degrees, from about 0 degrees to about 15 degrees, from about 0 degrees to about 10 degrees May also mean a case of having an inclination angle of about 0 degrees to about 5 degrees or about 0 degrees.

The liquid crystal film may further include a base layer, and an alignment layer and a liquid crystal layer may be sequentially formed on the base layer. Fig. 4 exemplarily shows a liquid crystal film including a base layer 401, an alignment film 101 and a liquid crystal layer 102 in sequence.

As the substrate layer, a known substrate layer material can be used without any particular limitation. As the base layer, for example, an inorganic film such as a glass film, a crystalline or amorphous silicon film, a quartz or an ITO (Indium Tin Oxide) film, or a plastic film can be used. The substrate layer may also be an optically isotropic substrate or an optically anisotropic substrate such as a retardation layer.

Plastic substrates 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 fluorine resin, or the like may be used as the substrate, but the present invention is not limited thereto. 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.

The present application also relates to a method for producing the liquid crystal film. The liquid crystal film may be prepared by, for example, applying an alignment film composition comprising an aligning material and a chiral agent, and curing the applied alignment film composition so that at least two alignment regions having different degrees of curing of the aligned alignment film composition are present, And then forming a liquid crystal layer on the cured alignment film composition. In the above manufacturing method, the content of the orienting material, the chiral agent, and the liquid crystal layer may be the same as described in the item of the liquid crystal film.

The alignment film composition can be prepared by dissolving the above-mentioned photo aligning compound and a chiral agent and / or a photoinitiator in an appropriate solvent. As the solvent, for example, a conventional organic solvent can be used. Examples of the solvent include an ether solvent, an aromatic solvent, a halogen solvent, an olefin solvent, and a ketone solvent. Specific examples thereof include cyclopentanone, cyclohexanone, chlorobenzene, N- Methylpyrrolidone, toluene, xylene, mesitylene, cymene, dimethylsulfoxide, dimethylformamide, chloroform, gamma butyrolactone or tetrahydrofuran. The application of the alignment film composition can be carried out, for example, on a substrate layer by a known coating method, and specifically, a roll coating, a printing method, an inkjet coating, a slit nozzle method, a bar coating, a comma coating, And the like, but is not limited thereto.

The alignment film composition can be cured, for example, by applying energy to the alignment film composition by irradiation of light or the like. When the alignment film composition contains a solvent or the like, irradiation with light may be carried out after the solvent is volatilized by drying under appropriate conditions. 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 alignment film composition can be aligned. Alignment of the oriented compound is typically carried out using linearly polarized light. The irradiation of the linearly polarized light in the above can be performed using, for example, a wire grid polarizer or the like. 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.

It is possible to cure such that at least two regions having different degrees of curing are present in the alignment film, for example, by adjusting the light quantity of the irradiated light. For example, in the item of the liquid crystal film, light having a light quantity in the range of 500 to 2000 mJ / cm 2 , more specifically 700 to 1000 mJ / cm 2 can be irradiated to the above-mentioned first alignment area, 50 to 500 mJ / cm < 2 >, more specifically, 100 to 500 mJ / It is possible to irradiate light having a light quantity within a range of 300 mJ / cm 2 . The range of the amount of light to be irradiated is not limited to the above range, but the amount of light to be irradiated may be different depending on the difference in the degree of curing desired.

The liquid crystal layer can be formed, for example, by applying a liquid crystal composition onto the cured alignment film composition and then polymerizing the liquid crystal composition. The liquid crystal composition can be produced, for example, by dissolving a polymerizable liquid crystal compound in a suitable solvent. Specifically, the liquid crystal composition can be prepared by dissolving a polymerizable liquid crystal compound and a photoinitiator in a solvent. In the liquid crystal composition, a surfactant, a polymerizable monomer, a polymer, and the like may be further added in addition to the above components within a range not interfering with the orientation of the liquid crystal molecules. The liquid crystal composition may be applied by, for example, a known coating method and may be applied by a roll coating method, a printing method, an ink jet coating method, a slit nozzle method, a bar coating method, a comma coating method, a spin coating method or a gravure coating method But is not limited thereto.

The polymerization method of the polymerizable liquid crystal compound is not particularly limited and can be carried out by a known liquid crystal compound polymerization method. For example, the polymerization may be carried out by maintaining the appropriate temperature at which the polymerization reaction is initiated or by irradiating a suitable active energy ray. When the maintenance at an appropriate temperature and the irradiation of the active energy ray are simultaneously required, the above process can be carried out sequentially or simultaneously. The irradiation of the active energy ray may be performed using, for example, a high-pressure mercury lamp, an electrodeless lamp, or a xenon lamp, and the conditions such as the wavelength, luminous intensity, Can be selected within a range in which the polymerization of the polymerizable liquid crystal compound can be properly carried out.

The present application also relates to an optical element including the liquid crystal film. The optical element may include, for example, two polarizing layers and a liquid crystal film existing between the two polarizing layers. The two polarizing layers may be arranged such that, for example, the transmission axes are orthogonal to each other. Fig. 5 exemplarily shows an optical element including a liquid crystal film existing between two polarizing layers 501 and 502. Fig.

As used herein, the term " polarizing layer " may mean a functional layer having a transmission axis formed in one direction and exhibiting an anisotropic transmission property with respect to incident light. For example, the polarizing layer may have a function of transmitting light that vibrates in one direction from incident light vibrating in various directions, and blocking or reflecting light that vibrates in the other direction.

As the polarizing layer, a known polarizing layer having a transmission axis formed in one direction can be used without any particular limitation. For example, a polarizing layer implemented by a coating method such as a lyotropic liquid crystal (LLC), a polarizing coating layer including a reactive liquid crystal (RM) and a dichroic dye, A polyvinyl chloride film or a wire grid polarizer in which a dichroic material is dyed can be used.

Such an optical element can cause, for example, light leakage different from each other in the first liquid crystal region and the second liquid crystal region of the liquid crystal film. For example, when the alignment direction of the alignment film of the liquid crystal film and the transmission axis of the polarizing layer are arranged to form about 45 degrees, the first region acts as QWF (Quarter Wave Film) and appears bright, And tends to appear dark. In another example, when the alignment direction of the alignment film of the liquid crystal film and the transmission axis of one of the two polarizing layers are arranged in parallel, the first region appears dark and the second region looks bright .

The present application also relates to the use of the liquid crystal film. The liquid crystal film can be applied to, for example, a device for counterfeiting or copying. The forgery or copy protection element may comprise, for example, the optical element. As described above, the optical element can selectively display a bright region and a dark region in the first and second liquid crystal regions, and thus can be usefully applied to counterfeiting or copy protection. The method for constructing such a counterfeit or copying prevention element is not particularly limited, and a conventional method can be applied as long as the optical element including the liquid crystal film is used.

The liquid crystal film of the present application can control the degree of photo-curing of an alignment film including an aligning material and a chiral agent to pattern the liquid crystal alignment of the liquid crystal layer formed on the alignment film. Such a liquid crystal film can be applied to, for example, a security device, a counterfeit or copy protection device.

Figs. 1 and 2 show an exemplary liquid crystal film.
Fig. 3 exemplarily shows the principle of diffusion of the chiral agent present in the alignment layer into the liquid crystal layer.
Fig. 4 exemplarily shows a liquid crystal film.
Fig. 5 exemplarily shows an optical element.
Figs. 6 to 8 show images of observation of transmittance between linearly polarizing plates of the liquid crystal film of Example 1 and Comparative Examples 1 and 2, respectively, which are orthogonal to each other.

Hereinafter, the present invention will be described more specifically with reference to the following examples, but the scope of the present invention is not limited by the following examples.

Example  One

Norbornene-2-methyl- (4-methoxy cinnamate), dipentaerythritol hexaacrylate, which is a monofunctional monomer, and photoacid generator, IGACURE 907 (Ciba-Geigy, Switzerland) LC756 from BASF, a chiral dopant, was dissolved in a cyclopentanone solvent at a concentration of 2% by weight, 2% by weight, 0.5% by weight and 0.5% by weight based on the total weight of the solution, respectively. The prepared composition for photo-alignment film was coated on one side of a glass substrate to a thickness of about 0.2 mu m after drying and dried in an oven at 80 DEG C for 2 minutes.

Subsequently, the composition for forming a photo-alignment layer was irradiated with ultraviolet rays of 300 mJ / cm 2 using a high-pressure mercury lamp, ultraviolet rays were masked with only a region for forming the second alignment region, and then a first alignment region was formed Was irradiated again with ultraviolet light of about 500 mJ / cm 2 to cure the composition for forming a photo alignment film. Subsequently, a wire grid polarizer (MoxTek) was used to measure a transmittance of about 100 mJ / cm 2 Polarized ultraviolet rays were irradiated and photo-alignment treatment was carried out to produce photo-alignment films having first and second alignment regions exhibiting mutually different degrees of curing.

Subsequently, a solid component consisting of 95% by weight of LC242 of BASF, a polymerizable liquid crystal compound capable of planar alignment and 5% by weight of a photoinitiator, IGACURE 907 (Ciba-Geigy, Switzerland) was dissolved in toluene solvent in an amount of 25% by weight After the polymerizable liquid crystal composition was prepared, the prepared polymerizable liquid crystal compound was applied onto the first and second alignment areas of the prepared photo alignment film so as to have a thickness of about 1 占 퐉 and dried in an oven at 80 占 폚 for 2 Minute, followed by curing by irradiating ultraviolet rays of 500 mJ / cm 2 with a high-pressure mercury lamp to produce a liquid crystal film of Example 1. In the liquid crystal film of Example 1, a visible pattern was observed in the first alignment region and the first alignment region between linearly polarizing plates orthogonal to each other as shown in Fig.

Comparative Example  One

A liquid crystal film was prepared in the same manner as in Example 1, except that a chiral agent (LC756, BASF) was not included in the composition for forming a photo alignment film. In the liquid crystal film of Comparative Example 1, as shown in Fig. 7, no visible pattern was observed between the orthogonal linear polarizers.

Comparative Example  2

A liquid crystal film was prepared in the same manner as in Example 1, except that ultraviolet light of 1000 mJ / cm 2 was used instead of ultraviolet light of 300 mJ / cm 2 in the first ultraviolet light irradiation step for curing the composition for forming a photo alignment film. As shown in Fig. 8, no noticeable pattern was observed between the linearly polarizing plates orthogonal to the liquid crystal film of Comparative Example 2 as well.

Observation of transmission between orthogonal polarizers

The liquid crystal films prepared in Example 1 and Comparative Examples 1 and 2 were placed between known perpendicularly polarizing linear polarizers, and the transmittance was observed. The results are shown in Figs. 6 to 8, respectively. 6A to 6C show images in a state in which the transmission axis of the polarizing plate orthogonal to the alignment direction of the photo alignment film is arranged at 45 degrees. Also shows an image in a rotated state.

As a result, in the liquid crystal film of Example 1, the first liquid crystal region was brightly displayed in the state (a) and darkly displayed in the state (b), and the second liquid crystal region of the liquid crystal film was ) State and dark in the state (b). From this, it can be confirmed that the liquid crystal film of Example 1 was patterned into the first liquid crystal region functioning as QWF and the second liquid crystal region functioning as the TN film.

On the other hand, in the case of the liquid crystal films of Comparative Examples 1 and 2, as shown in Figs. 7 to 8, the difference in the first and second liquid crystal regions was not noticeable, and the QWF function As shown in Fig. In Comparative Example 1, the chiral agent was not included in the composition for forming the photo alignment film. In Comparative Example 2, due to excessive UV curing of the photo alignment layer, the migration of the chiral agent to the liquid crystal layer in Comparative Examples 1 to 2 It seems to be because there is not.

101: Orientation film
1011: first orientation area
1012: second orientation area
102: liquid crystal layer
1021: first liquid crystal region
1022: second liquid crystal region
401: substrate layer
501, 502: first and second polarizing layers

Claims (12)

  1. And a liquid crystal layer which is in contact with the alignment layer, wherein the liquid crystal layer is a liquid crystal layer of a liquid crystal dopant existing on a surface opposite to a surface in contact with the alignment layer And an angle between the direction and the one direction is from -5 degrees to 5 degrees and the angle formed by the direction of the liquid crystal waveguide at the portion in contact with the alignment film and the direction of the liquid crystal waveguide at the surface opposite to the surface in contact with the alignment film is - The angle between the direction of the liquid crystal waveguide existing on the surface of the first liquid crystal region which is in the range of 5 degrees to 5 degrees and the surface on the opposite side to the surface in contact with the alignment film is less than -5 degrees or more than 5 degrees, And an angle formed by the direction of the liquid crystal waveguide at the portion in contact with the alignment film and the direction of the liquid crystal waveguide at the surface opposite to the surface in contact with the alignment film is 10 to 200 degrees A liquid crystal film made of a second liquid crystal region.
  2. The liquid crystal film according to claim 1, wherein the orienting material is a photo aligning material.
  3. The liquid crystal film according to claim 1, wherein the orientation film existing under the first liquid crystal region and the orientation film existing under the second liquid crystal region exhibit different degree of curing.
  4. delete
  5. delete
  6. The liquid crystal film according to claim 1, wherein the first liquid crystal region of the liquid crystal layer has a quarter-wave retardation characteristic and the second liquid crystal region has a twisted nematic liquid crystal orientation.
  7. The liquid crystal film according to claim 1, wherein the helical axis of the liquid crystal waveguide in the second liquid crystal region of the liquid crystal layer is formed parallel to the thickness direction of the liquid crystal layer.
  8. The liquid crystal film according to claim 1, wherein the liquid crystal layer comprises a compound represented by the following formula (1) in a crosslinked or polymerized form:
    [Chemical Formula 1]
    Figure 112014092315065-pat00003

    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, a cyano group, a nitro group, -OQP, Wherein at least one of R 1 to R 10 is -OQP or a substituent of the following formula 2, 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.
    (2)
    Figure 112014092315065-pat00004

    R 11 to R 15 each independently represent hydrogen, halogen, an alkyl group, an alkoxy group, a cyano group, a nitro group or -OQP, R 11 To R 15 At least one of them is -OQP wherein Q is an alkylene group or an alkylidene group and P is an alkenyl group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, It is a sunny season.
  9. The liquid crystal film according to claim 1, further comprising a base layer, wherein an alignment layer and a liquid crystal layer are sequentially formed on the base layer.
  10. An alignment film composition comprising an alignment material and a chiral agent is applied to the alignment film composition and the coated alignment film composition is cured so that at least two alignment regions having different degrees of curing of the cured alignment film composition are present, , And forming a liquid crystal layer on the cured alignment film composition.
  11. The optical element according to claim 1, comprising two polarizing layers arranged so that transmission axes are orthogonal to each other and the liquid crystal film of claim 1 existing between the two polarizing layers.
  12. delete
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JP4647782B2 (en) * 1998-06-11 2011-03-09 ロリク アーゲーRolic Ag Optical member, alignment layer and layerable polymerizable mixture
JP2013029827A (en) * 2011-06-22 2013-02-07 Nippon Zeon Co Ltd Pattern retardation plate, manufacturing method for the same and liquid crystal display

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EP1447689B1 (en) 1997-05-09 2012-08-22 Rolic AG Optical element comprising a structured retarder
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US8962103B2 (en) * 2010-11-10 2015-02-24 Lg Chem, Ltd. Liquid crystal film

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Publication number Priority date Publication date Assignee Title
JP4647782B2 (en) * 1998-06-11 2011-03-09 ロリク アーゲーRolic Ag Optical member, alignment layer and layerable polymerizable mixture
JP2013029827A (en) * 2011-06-22 2013-02-07 Nippon Zeon Co Ltd Pattern retardation plate, manufacturing method for the same and liquid crystal display

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