KR102466775B1 - Method for manufacturing a liquid crystal film - Google Patents

Abstract

This application relates to a method for manufacturing a liquid crystal film. The present application provides a method for manufacturing a liquid crystal film having excellent durability in a high temperature environment by reducing the water content in the liquid crystal film.

Description

Method for manufacturing a liquid crystal film {Method for manufacturing a liquid crystal film}

This application relates to a method for manufacturing a liquid crystal film.

A liquid crystal film can be used for various purposes.

A liquid crystal film may be disposed on one side or both sides of a liquid crystal cell in order to improve viewing angle characteristics of a liquid crystal display (LCD), for example. The liquid crystal film is also used to prevent reflection and secure visibility in a reflective LCD or OLED (Organic Light Emitting Device).

The liquid crystal film can be prepared by curing a polymerizable liquid crystal material, for example. At this time, a significant amount of moisture is inevitably contained in the liquid crystal material or the solvent. This causes deterioration of optical properties and durability of the manufactured liquid crystal film.

Japanese Laid-Open Patent Publication No. 1996-321381

The present application provides a method for manufacturing a liquid crystal film having excellent durability in a high temperature environment by reducing the water content in the liquid crystal film.

This application relates to a method for manufacturing a liquid crystal film. The method may include adding a water absorbent to a liquid crystal composition including a polymerizable liquid crystal compound and a solvent to reduce a water content in the liquid crystal composition. If the liquid crystal film has a high moisture content, it changes to water vapor at a high temperature and increases in volume, which may interfere with the alignment of the liquid crystal, and when it encounters a very small amount of acid or base material, the liquid crystal molecule chains may be broken (hydrolysis) . The liquid crystal film manufactured by the manufacturing method of the present application may have excellent durability in a high-temperature environment due to a decrease in water content in the liquid crystal film.

The polymerizable liquid crystal compound may have reverse wavelength dispersion, forward wavelength dispersion, or flat wavelength dispersion. Reverse wavelength dispersion may mean characteristics satisfying Equation 1 below, forward wavelength dispersion may mean characteristics satisfying Equation 2 below, and flat wavelength dispersion may mean characteristics satisfying Equation 3 below. have.

[Formula 1]

R(450)/R(550) < R(650)/R(550)

[Equation 2]

R(450)/R(550) > R(650)/R(550)

[Formula 3]

R(450)/R(550) ≒ R(650)/R(550)

In this specification, R(λ) may mean an in-plane retardation of light having a wavelength of λ nm. In Equations 1 to 3, R(450) is an in-plane retardation for light with a wavelength of 450 nm, R(550) is an in-plane retardation for light with a wavelength of 550 nm, and R(650) is an in-plane retardation for light with a wavelength of 650 nm. is the plane phase difference for light.

In this specification, the plane phase difference is a value determined according to Equation 4 below.

[Formula 4]

Rin = d × (nx - ny)

In Equation 4, Rin is the in-plane retardation, d is the thickness of the liquid crystal layer, nx and ny are the refractive index in the x-axis direction (slow axis direction) and the y-axis direction (fast axis direction) of the liquid crystal layer, respectively. may be equally applied in this specification unless otherwise specified. When the liquid crystal compound has a rod shape, the x-axis direction may mean a long axis direction of the rod shape, and the y-axis direction may mean a short axis direction of the rod shape. When the liquid crystal compound is disk-shaped, the x-axis direction may mean a normal direction of the disk-shaped disk, and the y-axis direction may mean a radial direction of the disk-shaped disk.

According to Equation 4, the in-plane retardation for light with a wavelength of 450 nm is nx and ny in Equation 4, the refractive index for light with a wavelength of 450 nm is applied, and the in-plane retardation for light with a wavelength of 550 nm is nx and The refractive index for light with a wavelength of 550 nm is applied as ny, and the refractive index for light with a wavelength of 650 nm is applied as nx and ny in Equation 4 for the in-plane retardation with respect to light with a wavelength of 650 nm.

In one example, the polymerizable liquid crystal compound may have reverse wavelength dispersion. In the present specification, a polymerizable liquid crystal compound having reverse wavelength dispersion may be referred to as a reverse dispersion liquid crystal. Inversely dispersed liquid crystals may have a low degree of curing because their molecules are larger than regular dispersed liquid crystals. Compared to regular dispersion liquid crystals, reverse dispersion liquid crystals do not sufficiently harden under the same curing conditions, so durability may be weak, and retardation values may decrease at high temperatures. Therefore, the manufacturing method of the liquid crystal film of the present application may be advantageous in improving the high-temperature durability of the reverse dispersion liquid crystal.

In the present specification, the polymerizable liquid crystal compound having reverse wavelength dispersion may refer to a polymerizable liquid crystal compound in which a liquid crystal layer formed by curing the polymerizable liquid crystal compound alone exhibits reverse wavelength dispersion of Equation 1.

In the present specification, wavelength dispersion and retardation values may refer to wavelength dispersion and retardation values for a liquid crystal layer formed by curing a polymerizable liquid crystal compound in a state in which it is aligned on the xy plane unless otherwise specified. have.

The polymerizable liquid crystal compound may have an R(450)/R(550) value of 0.99 or less. In one example, the R(450)/R(550) may be in the range of 0.6 to 0.99. R(450)/R(550) is, in another example, 0.61 or more, 0.62 or more, 0.63 or more, 0.64 or more, 0.65 or more, 0.66 or more, 0.67 or more, 0.69 or more, 0.70 or more, 0.71 or more, 0.72 or more, 0.73 or more, 0.74 or more, 0.75 or more, 0.76 or more, 0.77 or more, 0.78 or more, 0.79 or more, 0.80 or more, 0.81 or more, 0.82 or more, 0.83 or more or 0.84 or more. The R(450)/R(550) is, in another example, 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less, 0.89 or less, 0.88 or less, 0.87 or less , may be less than or equal to 0.86 or less than or equal to 0.85.

The polymerizable liquid crystal compound may have an R(650)/R(550) value of 1.01 or more. In one example, the R(650)/R(550) may be in the range of 1.01 to 1.19. The R(650)/R(550) may be 1.18 or less, 1.17 or less, 1.16 or less, 1.15 or less, 1.14 or less, 1.13 or less, 1.12 or less, or 1.11 or less. The R(650)/R(550) may be 1.01 or more, 1.02 or more, 1.03 or more, 1.04 or more, 1.05 or more, 1.06 or more, 1.07 or more, 1.08 or more, or 1.09 or more in another example.

The polymerizable liquid crystal compound having the above R(450)/R(550) and/or R(650)/R(550) values is not particularly limited. As polymerizable liquid crystal compounds having reverse wavelength dispersion in this field, polymerizable liquid crystal compounds having R(450)/R(550) and/or R(650)/R(550) in the above ranges are known, and such polymerization It can be used by selecting a sexual liquid crystal compound.

It is known that the birefringence of polymerizable liquid crystal compounds is mainly determined by molecular conjugation structure, differential oscillator strength, and order parameters. Since a large electron density is required, most polymerizable liquid crystal compounds have a highly conjugated shape in the long axis direction.

In order for the polymerizable liquid crystal compound to exhibit reverse wavelength dispersion, it is necessary to adjust the birefringence between the long axis and the axis perpendicular to it, and accordingly, the polymerizable liquid crystal compound designed to have reverse wavelength dispersion is mostly T Alternatively, it may have an H-shaped molecular shape with a major axis (major axis) having a large phase difference and a small dispersion value, and an axis perpendicular thereto having a small phase difference and a large dispersion value.

For example, PCT-JP2015-083728, PCT-JP2015-085342, PCT-JP2016-050322, PCT-JP2016-050660, PCT-JP2016-050661, PCT-JP2016-050984 and PCT-JP2016-050663 disclosed polymeric liquid crystals and the like. Among the compounds, some of the polymerizable liquid crystal compounds are polymerizable liquid crystal compounds with reverse wavelength dispersion, and in the present application, the above polymerizable liquid crystal compounds may be applied, but the types of polymerizable liquid crystal compounds applicable in the present application are the above. It is not limited thereto, and various types of polymerizable liquid crystal compounds may be used as long as they have reverse wavelength dispersion.

In one example, the polymerizable liquid crystal compound having reverse wavelength dispersion may be a compound represented by Formula 1 below.

[Formula 1]

In Formula 1, Ar is an aromatic group having a heterocyclic ring, L ₁ to L ₄ are each independently a single bond, an alkylene group, an alkenylene group, an alkynylene group, -COO-, -OCO- or -OQ ₁ -, and , wherein R ₁ to R ₁₀ are each independently hydrogen, halogen, alkyl group, alkenyl group, alkynyl group, alkoxy group, alkoxycarbonyl group, cyano group, nitro group, -OQ ₂ -P ₁ , -[Q ₃ -COO] _a1 -Q ₄ -P ₂ or -[Q ₅ -COO] _a2 -Q ₆ -OQ ₇ -P ₃ , wherein Q ₁ to Q ₇ are each independently an alkylene group, an alkenylene group or an alkynylene group, and P ₁ to P ₃ are each a polymerizable functional group, a1 to a2 are each independently an integer of 1 to 4, n and m are each independently an integer of 1 to 10, and Chemical Formula 1 includes one or more polymerizable functional groups. include

In Formula 1, Ar is an aromatic group having a heterocycle, and the heterocycle is bonded to one substituent on the aromatic group, or two adjacent substituents of the aromatic group are linked to form the heterocycle, There may be.

In one example, Ar in Formula 1 may be represented by Formulas 2 to 4 below.

[Formula 2]

In Formula 2, * may mean a binding site to L ₂ and L ₃ of Formula 1. In Formula 2, R ₁₁ is a substituent represented by Formula 5, and R ₁₂ is each independently hydrogen, halogen, alkyl group, alkenyl group, alkynyl group, alkoxy group, alkoxycarbonyl group, cyano group, nitro group, or -OQ ₈ -P ₄ , wherein Q ₈ is an alkylene group, an alkenylene group or an alkynylene group, P ₄ is a polymerizable functional group, and b is an integer of 1 to 3.

[Formula 3]

In Formula 3, * means a binding site to L ₂ and L ₃ of Formula 1. In Formula 3, L ₅ is a single bond, an alkylene group, an alkenylene group, an alkynylene group, -COO-, -OCO-, -OQ ₉ -, and R ₁₃ to R ₁₉ are each independently hydrogen, a halogen, an alkyl group, An alkenyl group, an alkynyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group, or -OQ ₁₀ -P ₅ , Q ₉ and Q ₁₀ are each independently an alkylene group, an alkenylene group or an alkynylene group, and P ₅ is a polymerizable functional group.

[Formula 4]

In Formula 4, * means a binding site to L ₂ and L ₃ of Formula 1. In Formula 4, L ₇ is a single bond, an alkylene group, an alkenylene group, an alkynylene group, -COO-, -OCO-, -OQ ₁₁ -, and R ₂₁ to R ₂₃ are each independently hydrogen, a halogen, an alkyl group, An alkenyl group, an alkynyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group, -OQ ₁₁ -P ₆ , Q ₁₁ is an alkylene group, an alkenylene group or an alkynylene group, P ₆ is a polymerizable functional group, c is an integer of 1 or 2;

[Formula 5]

In Formula 5, * means a binding site to benzene in Formula 2. In Formula 5, L ₇ is a single bond, an alkylene group, an alkenylene group, an alkynylene group, -COO-, -OCO-, -OQ ₁₂ -, or may be represented by Formula 6 below, and R ₂₃ to R _{26 are} each independently hydrogen, halogen, alkyl group, alkenyl group, alkynyl group, alkoxy group, alkoxycarbonyl group, cyano group, nitro group, -OQ ₁₃ -P ₇ , -[Q ₁₄ -COO] _a3 -Q ₁₅ - P ₈ or -[Q ₁₆ -COO] _a4 -Q ₁₇ -OQ ₁₈ -P ₉ , Q ₁₂ to Q ₁₈ are each independently an alkylene group, an alkenylene group or an alkynylene group, and P ₈ and P ₉ are each independently It is independently a polymerizable functional group, and a3 to a4 are each independently an integer of 1 to 4.

[Formula 6]

In Formula 6, * means a binding site to benzene in Formula 2 and Formula 5. In Formula 6, L ₈ may be a single bond, an alkenyl group, an alkenylene group, or an alkynylene group, and R ₂₇ is hydrogen, halogen, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, or a nitro group. , -[Q ₁₉ -O]a ₅ -Q ₂₀ -P ₁₀ , or -[Q ₂₁ -O]a ₆ -Q ₂₂ , and Q ₁₉ to Q ₂₁ are each independently an alkylene group, an alkenylene group, or an alkynyl group. It is a rene group, P ₁₀ is a polymerizable functional group, and Q ₂₃ is an alkyl group, an alkenyl group or an alkynyl group.

In this specification, halogen may be exemplified by chlorine, bromine or iodine.

In this specification, an alkyl group or an alkylene group is a straight or branched chain alkyl group or an alkylidene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, and 1 to 4 carbon atoms, unless otherwise specified, or It may mean a cycloalkyl group or an alkylidene group having 3 to 20 carbon atoms, 3 to 16 carbon atoms, or 4 to 12 carbon atoms. The alkyl group or alkylene group may be optionally substituted by one or more substituents.

In the present specification, the alkenyl group or alkenylene group has 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, and 1 to 4 carbon atoms unless otherwise specified. or a cycloalkenyl group or an alkenylene group having 3 to 20 carbon atoms, 3 to 16 carbon atoms, or 4 to 12 carbon atoms. The alkenyl group or alkenylene group may be optionally limited by one or more substituents.

In this specification, an alkynyl group or alkynylene group is a straight-chain or branched-chain alkynyl group or alkynylene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, and 1 to 4 carbon atoms unless otherwise specified. or a cycloalkynyl group or alkynylene group having 3 to 20 carbon atoms, 3 to 16 carbon atoms, or 4 to 12 carbon atoms. The alkynyl group or alkynylene group may be optionally limited by one or more substituents.

The polymerizable liquid crystal compound may have a refractive index anisotropy (Δn) of 0.03 to 0.13 for light having a wavelength of 550 nm. In the present specification, refractive index anisotropy may mean a difference (ne-no) between an extraordinary refractive index (ne) and an ordinary refractive index (no) of a liquid crystal compound. The abnormal refractive index may mean a refractive index of the liquid crystal compound in a slow axis direction, and the normal refractive index may mean a refractive index of the liquid crystal compound in a fast axis direction.

In the present specification, the term "polymerizable liquid crystal compound" may refer to a compound that includes a site capable of exhibiting liquid crystallinity, for example, a mesogen backbone, and includes one or more polymerizable functional groups. . These polymerizable liquid crystal compounds are variously known as so-called RM (Reactive Mesogen). The polymerizable liquid crystal compound may be included in a polymerized form in the cured layer of the liquid crystal film, which indicates 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 cured layer. can mean

The polymerizable liquid crystal compound may be a monofunctional or multifunctional polymerizable liquid crystal compound. In the above, the monofunctional polymerizable liquid crystal compound may refer to a compound having one polymerizable functional group, and the multifunctional polymerizable liquid crystal compound may refer to a compound containing two or more polymerizable functional groups. In one example, the multifunctional polymerizable liquid crystal compound has 2 to 10, 2 to 8, 2 to 6, 2 to 5, 2 to 4, 2 to 3 polymerizable functional groups. or two or three. The liquid crystal composition may include polymerizable liquid crystal compounds having the same polymerizable functional group or two or more polymerizable liquid crystal compounds having different polymerizable functional groups.

The polymerizable functional group may be, for example, an alkenyl group, an epoxy group, a carboxyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group, but is not limited thereto.

Examples of the solvent included in the liquid crystal composition include aromatic hydrocarbons such as toluene, benzene, and xylene; aliphatic hydrocarbons such as cyclohexane and decalin; esters such as ethyl acetate and butyl acetate; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve, and butyl cellosolve; ethers such as tetrahydrofuran and dioxane; halogenated hydrocarbons such as dichloromethane, chloroform, and carbon tetrachloride; dimethylformamide; Dimethyl sulfoxide etc. are mentioned. These solvents may be used independently or may use 2 or more types together.

The liquid crystal composition may include 20 to 50 parts by weight of the polymerizable liquid crystal compound based on solid content, based on 100 parts by weight of the solvent. Within this range, the liquid crystal composition may exhibit suitable reverse wavelength dispersion. The proportion of the polymerizable liquid crystal compound in the cured layer of the liquid crystal composition may also be present within the aforementioned range.

The moisture absorbent may function to reduce the moisture content in the liquid crystal composition by absorbing moisture in the liquid crystal composition. Moisture in the liquid crystal composition may be included in the liquid crystal compound or the solvent.

The moisture absorbent is, for example, silica gel, zeolite, CaO, BaO, MgSO ₄ , Mg(ClO ₄ ) ₂ , MgO, P ₂ O ₅ , Al ₂ O ₃ , CaH ₂ , NaH, LiAlH ₄ , CaSO ₄ , Na ₂ SO ₄ , CaCO ₃ , K ₂ CO ₃ , CaCl ₂ , 4A and 3A molecular sieves, Ba(ClO ₄ ) ₂ , at least one selected from the group consisting of cross-linked poly(acrylic acid) and poly(acrylic acid) can include According to an embodiment of the present application, MgSO ₄ may be used as a moisture absorbent.

The content of the moisture absorbent added to the liquid crystal composition may be appropriately adjusted within a range not impairing the purpose of the present application. In one example, the water absorbent may be included in 3 to 7 parts by weight based on 100 parts by weight of the liquid crystal composition. If the content of the moisture absorbent is too small, it may not be able to sufficiently absorb moisture in the liquid crystal composition, and if the content is too high, it may be adsorbed with other materials and a lot of effort may be required to filter it out through a filter. It may be advantageous to adjust within the range.

The method may further include shaking the liquid crystal composition to which the moisture absorbent is added. This step may be performed after adding the moisture absorbent to the liquid crystal composition, and through this, the moisture absorbent sufficiently absorbs moisture in the liquid crystal composition, thereby reducing the moisture content in the liquid crystal composition. A method of shaking the liquid crystal composition is not particularly limited, and for example, a shaker or a vortex mixer may be used.

The shaking time of the liquid crystal composition may be appropriately selected within a range that does not impair the purpose of the present application. In one example, the liquid crystal composition to which the moisture absorbent is added may be shaken for 30 seconds to 3 minutes. If the shaking time of the liquid crystal composition to which the moisture absorbent is added is too short, the moisture in the liquid crystal composition may not be sufficiently absorbed, and if it is too long, the moisture absorbent that has become agglomerated by holding moisture may be broken again and redeposit moisture. , the time may be advantageously adjusted within the above range.

The method may further include separating the moisture absorbent from the liquid crystal composition. This step may be performed after the step of shaking the liquid crystal composition to which the moisture absorbent is added. In the step of shaking the liquid crystal composition, the moisture absorbent may be in a state in which moisture of the liquid crystal composition has been absorbed. If the moisture absorbent is not separated from the liquid crystal composition, since the moisture absorbent absorbs moisture and forms a mass of hundreds of μm or more, thin film coating itself may not be performed. Even if the coating is possible, since there is a concern that it will become a source for redistribution of moisture in the future, the moisture absorbent must be separated from the liquid crystal composition. A method of separating the moisture absorbent from the liquid crystal composition is not particularly limited, and may be performed by, for example, a known filter method. Since the moisture absorbent that has absorbed moisture is in a lump of several hundred μm or more, it is easy to separate, so the filter method is not particularly limited, but it can be carried out using, for example, a syringe filter or filter paper.

The method may further include applying the liquid crystal composition whose water content is reduced by a water absorbent onto a base film. This step may be performed after reducing the moisture content using the moisture absorbent and/or separating the moisture absorbent from the liquid crystal composition. At this time, the liquid crystal composition may be applied on the base film to have a thickness of 1 μm to 3 μm after drying.

The method of applying the liquid crystal composition on the base film is not particularly limited, and examples thereof include known coatings such as roll coating, printing method, inkjet coating, slit nozzle method, bar coating, comma coating, spin coating, or gravure coating. It can be performed by coating through the method.

As the base film, a known material can be used without particular limitation. For example, an inorganic substrate such as a glass substrate, a crystalline or amorphous silicon substrate, quartz or indium tin oxide (ITO), or a plastic film may be used. As the substrate layer, an optically anisotropic substrate layer such as an optically isotonic substrate layer or a retardation layer can be used.

As a plastic film, TAC (triacetyl cellulose); COP (cyclo olefin copolymer), such as a norbornene derivative; PMMA (poly(methyl methacrylate); PC (polycarbonate); PE (polyethylene); PP (polypropylene); PVA (polyvinyl alcohol); DAC (diacetyl cellulose); Pac (polyacrylate); PES (poly ether sulfone); PEEK (polyetheretherketon ); PPS (polyphenylsulfone), PEI (polyetherimide); PEN (polyethylenemaphthatlate); PET (polyethyleneterephtalate); PI (polyimide); PSF (polysulfone); PAR (polyarylate) or an amorphous fluorine resin. The substrate layer may have 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, if necessary.

An alignment layer may be formed on one surface of the base film. The liquid crystal composition may be applied to the surface of the base film on which the alignment layer is formed. As the alignment layer, any layer having alignment ability with respect to adjacent layers of the liquid crystal composition may be selected and used without particular limitation. For example, a contact alignment layer such as a rubbing alignment layer or a photo-alignment layer including a photo-alignment compound and exhibiting alignment characteristics by a non-contact method such as irradiation of linearly polarized light may be used.

In one example, the alignment layer may be a photo alignment layer. The photo-alignment layer may include a photo-alignment compound. The photo-alignment compound may mean, for example, a compound that is aligned by a photo-isomerization reaction, a photolysis reaction, or a photo-dimerization reaction by light irradiation and exhibits liquid crystal alignment, and is preferably light by polarized ultraviolet irradiation. It may be a compound exhibiting liquid crystal orientation through a dimerization reaction.

In this specification, the term liquid crystal alignment refers to a property that can align liquid crystal molecules, liquid crystal compounds, or precursors thereof adjacent to an alignment film, an optical alignment compound, or a reactant of the compound in a predetermined direction.

The photo-alignment compound may be a compound containing a photosensitive moiety. Various photo-alignment compounds that can be used for alignment of liquid crystals are known. Examples of the photo-alignment compound include compounds aligned by trans-cis photoisomerization; compounds ordered by photo-destruction such as chain scission or photo-oxidation; compounds aligned by photocrosslinking or photopolymerization, such as [2+2] cycloaddition, [4+4] cycloaddition or photodimerization; A compound aligned by photo-Fries rearrangement or a compound aligned by ring opening/closure reaction or the like can be used. Examples of the compound aligned by trans-cis photoisomerization include azo compounds such as sulfonated diazo dyes or azo polymers, stilbenes, and the like. Cyclobutane tetracarboxylic dianhydride (cyclobutane-1,2,3,4-tetracarboxylic dianhydride), aromatic polysilane or polyester, polystyrene, or polyimide may be exemplified as the compound that is aligned by photolysis. In addition, the compounds aligned by photocrosslinking or photopolymerization include cinnamate compounds, coumarin compounds, cinnamamide compounds, tetrahydrophthalimide compounds, and maleimide compounds. , benzophenone compounds or diphenylacetylene compounds, compounds having a chalconyl residue as a photosensitive residue (hereinafter referred to as chalcone compounds) or compounds having anthracenyl residues (hereinafter referred to as anthracenyl compounds), etc. This can be exemplified, and the compounds aligned by light frieze rearrangement include aromatic compounds such as benzoate compounds, benzoamide compounds, and methacrylamidoaryl methacrylate compounds. It can be exemplified, and compounds aligned by ring-opening / ring-closing reactions are aligned by ring-opening / ring-closing reactions of [4 + 2] π-electronic systems, such as spiropyran compounds. Compounds and the like may be exemplified, but are not limited thereto.

The photo-alignment compound may be a monomolecular compound, a monomeric compound, an oligomeric compound, or a polymeric compound, or a blend of an optical alignment material and a polymer. In the above, the oligomeric or polymeric compound may have a residue derived from the photo-alignment material or the photosensitive residue described above in a main chain or a side chain.

The photo-alignment layer may further include a reactive compound having at least one functional group capable of reacting with the photo-alignment compound. The reactive compound may include preferably 2 or more, more preferably 2 to 10, more preferably 4 to 10, and more preferably 4 to 8 functional groups. Preferably, the functional group may have reactivity with a liquid crystal compound of a layer of a liquid crystal composition or a liquid crystal layer on an alignment layer or a precursor for forming the liquid crystal compound. The reactive compound is, for example, a reaction performed by a photo-alignment compound in a mixture to exhibit liquid crystal orientation in the process of irradiating light to the mixture to form an alignment layer or irradiating light to form a liquid crystal layer; For example, an additional reaction separate from the photodimerization reaction may be induced.

The additional reaction may include a cross-linking reaction between the photo-alignment compounds, a cross-linking reaction between the photo-alignment compound and the reactive compound or liquid crystal molecules and the reactive compound, and a cross-linking reaction between the photo-alignment compound and the liquid crystal molecules.

In the above, the functional group capable of reacting with the photo-alignment compound and/or the liquid crystal molecule is, for example, one that can be crosslinked with the photo-alignment compound and/or the liquid crystal molecule by a free radical reaction, and includes an ethylenically unsaturated double bond. A functional group may be exemplified.

Specific examples of the functional group may include one or more kinds of an alkenyl group, an epoxy group, a cyano group, a carboxyl group, an acryloyl group, or a methacryloyl group, and preferably a vinyl group, an allyl group, an acryloyl group, or a meta It may be a acryloyl group, more preferably an acryloyl group or a methacryloyl group, but is not limited thereto.

In one example, it may be preferable to use a multifunctional acrylate as the reactive compound, more preferably pentaerythritol triacrylate, dipentaerythritol hexaacrylate, tris [2- (acrylo yloxy)ethyl] polyfunctional acrylates such as isocyanurate or urethane acrylate may be used, but are not limited thereto. As an example of the urethane acrylate above, compounds distributed under trade names such as EB1290, UP135, UP111 or UP128 by Cytec may be exemplified, but are not limited thereto.

The photo-alignment layer may further include a photoinitiator. As the photoinitiator, for example, any photoinitiator capable of inducing a free radical reaction by irradiation of light may be used without particular limitation. As such a photoinitiator, an α-hydroxy ketone compound, an α-amino ketone compound, a phenyl glyoxylate compound, or an oxime ester compound may be exemplified, and an oxime ester compound may be preferably used.

The photo-alignment layer may contain 0.1 to 20 parts by weight of a photo-alignment compound, preferably 0.1 to 10 parts by weight; 0.1 to 20 parts by weight of the reactive compound, preferably 0.1 to 15 parts by weight, more preferably 0.1 to 5 parts by weight; and 0.01 part by weight to 5 parts by weight, preferably 0.01 part by weight to 2 parts by weight of the photoinitiator.

A good alignment layer can be obtained at an appropriate ratio of the photo-alignment compound and an appropriate thickness of the alignment layer, and an appropriate crosslinking reaction can be induced while maintaining the orientation of the alignment layer at the ratio of the reactive compound and the photoinitiator.

In particular, the photo-alignment layer preferably includes 10 parts by weight to 1,000 parts by weight, preferably 25 parts by weight to 400 parts by weight of the reactive compound based on 100 parts by weight of the photo-alignment compound. At this ratio, it is possible to maintain excellent adhesion to the substrate or liquid crystal layer and alignment of the alignment layer.

The method may further include drying the layer of the liquid crystal composition applied on the base film. This step may be performed after applying the liquid crystal composition on the base film. The drying may be performed through hot air drying. Drying of the solvent included in the liquid crystal composition and the residual moisture content may be reduced through the hot air drying process.

Conditions for the hot air drying may be appropriately selected within a range that does not impair the purpose of the present application.

In the example below, hot air drying may be performed within a range of 70 °C to 90 °C. If the temperature of the hot air drying is too low or too high, there is a concern that the orientation of the liquid crystal may deteriorate, so it may be advantageous that the hot air drying temperature is adjusted within the above range.

In one example, hot air drying may be performed for 1 minute to 5 minutes. If the hot air drying time is too short or long, there is a concern that the orientation of the liquid crystal may deteriorate, so it may be advantageous to adjust the hot air drying time within the above range.

The method may be prepared by curing a layer of a liquid crystal composition. A method of curing the liquid crystal composition is not particularly limited, and may be performed by a known liquid crystal compound polymerization method. For example, it may be performed by maintaining an appropriate temperature or irradiating an appropriate active energy ray so that the polymerization reaction can be initiated. When maintenance at an appropriate temperature and irradiation of active energy rays are simultaneously required, the above process may be performed sequentially or simultaneously. In the above, 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 conditions such as the wavelength, luminous intensity, or light amount of the radiated active energy ray are as described above. It may be selected within a range in which polymerization of the polymerizable liquid crystal compound can be properly performed.

In one example, the method may include irradiating ultraviolet rays to the layer of the liquid crystal composition applied on the base film. This step may be performed after applying the liquid crystal composition on the base film and/or drying the layer of the applied liquid crystal composition. In this case, the ultraviolet light may be unpolarized ultraviolet light. A wavelength range of the irradiated UV light may be, for example, 150 nm to 350 nm. The amount of light of the irradiated ultraviolet rays is 50 mJ/cm ² to 5000 mJ/cm ² can be

In one example, the liquid crystal film manufactured according to the above method may sequentially include a base film, an alignment layer on the base film, and a liquid crystal layer on the alignment layer. The liquid crystal layer may include the liquid crystal composition in a cured state. The liquid crystal layer may include the polymerizable liquid crystal compound in a polymerized state.

The liquid crystal film manufactured according to the above method may exhibit excellent durability in a high temperature environment due to a decrease in water content. The liquid crystal film may have a low retardation change rate in high-temperature durability evaluation.

In one example, the liquid crystal film manufactured according to the manufacturing method may have an absolute value of retardation change rate (ΔRin) calculated by Equation 5 below of 2.0%, 1.8%, 1.6%, 1.4%, or 1.2%. can

[Formula 5]

ΔRin=(1-Rin ₂ /Rin ₁ ) Х 100

ΔRin is the in-plane retardation change rate after heating, Rin ₁ is the initial in-plane retardation value, and Rin ₂ is the in-plane retardation value after heating at 80° C. for 300 hours. The initial in-plane retardation value means the in-plane retardation value at room temperature before heating. In the present specification, normal pressure may mean a temperature in a state where the temperature is not artificially controlled. Room temperature may mean, for example, a temperature within a range of 20 degrees to 40 degrees and a range of 20 degrees to 30 degrees.

This application also relates to the use of a liquid crystal film. The liquid crystal film may be used to provide a polarizing plate. The polarizing plate may include a polarizer and the liquid crystal film disposed on one surface of the polarizer.

In this specification, the term polarizer refers to a film, sheet, or device having a polarization function. A polarizer is a functional element capable of extracting light vibrating in one direction from incident light vibrating in several directions. In this specification, a polarizer may mean a film, sheet, or device itself having the polarizing film, and a polarizing plate may mean an element further including other layers in addition to the polarizer. Examples of the other layers include an optically anisotropic film, a protective substrate layer, a pressure-sensitive adhesive layer, and an adhesive layer.

The polarizer may be an absorption type polarizer. In this specification, an absorption type polarizer refers to an element that exhibits selective transmission and absorption characteristics with respect to incident light. For example, the polarizer may transmit light vibrating in one direction from incident light vibrating in several directions and absorb light vibrating in the other direction.

The polarizer may be a linear polarizer. In this specification, a linear polarizer means a case in which selectively transmitted light is linearly polarized light vibrating in one direction and selectively absorbed light is linearly polarized light vibrating in a direction orthogonal to the vibrational direction of the linearly polarized light.

As the polarizer, for example, a polarizer in which iodine is dyed on a polymer stretched film such as a PVA stretched film, or a liquid crystal polymerized in an aligned state as a host and an anisotropic dye arranged according to the alignment of the liquid crystal as a guest A guest-host type polarizer may be used, but is not limited thereto.

According to one embodiment of the present application, a stretched PVA film may be used as the polarizer. Transmittance or polarization degree of the polarizer may be appropriately adjusted in consideration of the purpose of the present application. For example, the transmittance of the polarizer may be 42.5% to 55%, and the degree of polarization may be 65% to 99.9997%.

In one example, when the polarizing plate is used as a circular polarizing plate or an elliptically polarizing plate, the liquid crystal film may have 1/4 wavelength retardation characteristics. In this specification, the term n-wavelength phase retardation characteristic means a characteristic capable of delaying the phase of incident light by n times the wavelength of the incident light within at least a part of the wavelength range. The 1/4 wavelength phase delay characteristic may be a characteristic of converting incident linearly polarized light into elliptically polarized light or circularly polarized light, and conversely converting incident elliptically polarized light or circularly polarized light into linearly polarized light.

When the polarizing plate is used as a circular polarizing plate or an elliptically polarizing plate, the slow axis of the liquid crystal film and the light absorption axis of the polarizer may form an angle within a range of about 30 degrees to about 60 degrees. The angle may be 35 degrees or more or 40 degrees or more in another example, and may also be 55 degrees or less or 50 degrees or less.

In another example, in order to use the polarizing plate as an optical compensation polarizing plate other than a circular polarizing plate or an elliptically polarizing plate, the in-plane retardation value of the liquid crystal film is a phase retardation characteristic other than a quarter wavelength retardation characteristic, for example, 1 /2 wavelength phase delay characteristics, etc., and the angle formed by the slow axis of the optically anisotropic layer and the polarizer may be appropriately adjusted in consideration of the purpose to which it is applied.

In one example, the liquid crystal film may have an in-plane retardation of light having a wavelength of 550 nm within a range of 90 nm to 300 nm. In another example, the in-plane retardation may be 100 nm or more, 105 nm or more, 110 nm or more, 115 nm or more, 120 nm or more, 125 nm or more, or 130 nm or more. In addition, the in-plane retardation is 290 nm or less, 280 nm or less, 270 nm or less, 260 nm or less, 250 nm or less, 240 nm or less, 230 nm or less, 220 nm or less, 210 nm or less, 200 nm or less, 190 nm or less, 180 nm or less, 170 nm or less, 160 nm or less, 150 nm or less, or 145 nm or less.

The polarizing plate may further include a protective substrate layer. The protective substrate layer may be disposed on a side opposite to the side of the polarizer facing the liquid crystal film. The protective substrate layer may be attached to one surface of the polarizer via an adhesive layer. In this specification, "protective base layer" may mean a base layer that is disposed on one surface of the polarizer and performs a function of protecting the polarizer as described above. Meanwhile, the base film of the liquid crystal film may also serve as a protective base layer of the polarizer by being attached to the other surface of the polarizer.

A film of a known material may be used as the protective substrate layer. As such a material, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier property, or isotropic property may be used. Examples of such resins include cellulose resins such as TAC (triacetyl cellulose), polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, Cyclic polyolefin resins such as norbornene resins, polyarylate resins, polystyrene resins, polyvinyl alcohol resins, or mixtures thereof may be exemplified. The protective substrate layer may further include a surface treatment layer on one side of the film. Examples of the surface treatment layer include an antireflection layer and a hard coating layer, but are not limited thereto.

The polarizing plate may further include a pressure-sensitive adhesive layer or an adhesive layer. In one example, the polarizer and the liquid crystal film may be attached via the pressure-sensitive adhesive layer or the adhesive layer.

In one example, the polarizing plate may further include an adhesive layer on a side opposite to the polarizer of the liquid crystal film. The pressure-sensitive adhesive layer may perform a function of attaching the polarizing plate to a display element described later. As the pressure-sensitive adhesive or adhesive, known pressure-sensitive adhesives or adhesives such as acrylic, epoxy-based, silicone-based, rubber-based, and urethane-based adhesives may be used without particular limitation.

The polarizing plate of the present application may have various other structures within a range that does not impair the object of the present invention, as long as it basically includes the polarizer and the liquid crystal film.

The liquid crystal film and/or the polarizing plate may be applied to a display device. A display device is a device having a display element, and includes a light emitting element or a light emitting device as a light emitting source. As the display device, a liquid crystal display device, an organic electroluminescence (EL) display device, an inorganic electroluminescence (EL) display device, a touch panel display device, an electron emission display device (electric field emission display device (FED, etc.), surface field emission display (SED)), electronic paper (display device using electronic ink or electrophoretic element), plasma display device, projection type display device (grating light valve (GLV) display device, digital micro mirror device (DMD)) a display device having the same), a piezoelectric ceramic display, and the like. The liquid crystal display device includes any one of a transmission type liquid crystal display device, a transflective type liquid crystal display device, a reflection type liquid crystal display device, a direct view type liquid crystal display device, and a projection type liquid crystal display device. These display devices may be display devices that display two-dimensional images or stereoscopic display devices that display three-dimensional images.

In particular, the circular polarizing plate can be effectively used in organic EL display devices and inorganic EL display devices, and the optical compensation polarizing plate can be effectively used in liquid crystal display devices and touch panel display devices.

The arrangement form of the polarizing plate in the display device is not particularly limited, and, for example, a known form may be employed. For example, in a reflective liquid crystal display device, a circular polarizing plate may be used as any one of the circular polarizing plates of a liquid crystal panel in order to prevent reflection of external light and secure visibility.

When a polarizing plate is applied to the organic light emitting device, the organic light emitting device includes a reflective electrode, a transparent electrode, an organic layer interposed between the reflective electrode and the transparent electrode, and having a light emitting layer, and one surface of the organic light emitting device. It may include the circular polarizing plate disposed on. The circular polarizing plate may be present outside the reflective or transparent electrode, and an optically anisotropic layer may be disposed closer to the reflective or transparent electrode than the linear polarizer.

The present application provides a method for manufacturing a liquid crystal film having excellent durability in a high temperature environment by reducing the water content in the liquid crystal film.

Hereinafter, the present application will be specifically described through examples according to the present application and comparative examples not according to the present application, but the scope of the present application is not limited by the examples presented below.

Example One

20 g of photo-alignable polymer 5-norbornene-2-methyl-(4-methoxy cinnamate), 20 g of dipentaerythritol hexaacrylate as a reactive compound, and a photoinitiator (Irgacure OXE02, Ciba-Geigy Co., Ltd. (Switzerland) F) 5 g of cyclopentanone was dissolved in 980 g of cyclopentanone to prepare an alignment layer composition, and the alignment layer composition was applied on a polycarbonate film to a thickness of about 1,000 Å after drying, and then in a drying oven at 80° C. for 2 minutes dried in hot air. After drying, a high-pressure mercury lamp is used as a light source, and linearly polarized ultraviolet rays are irradiated in a direction perpendicular to the traveling direction of the film through a wire grid polarizer (manufactured by Moxtek) at a light amount of 150 mJ/cm ² to impart orientation. An alignment layer was prepared.

A polymerizable liquid crystal compound capable of plane alignment and having reverse wavelength dispersion (manufactured by DIC) UCL-R17 mixture was added to toluene as a solvent so that the solid content was 35 parts by weight based on 100 parts by weight of the total composition (solvent + UCL-R17 mixture) A liquid crystal composition was prepared by dissolution.

Thereafter, 5 wt% of MgSO ₄ was mixed with the liquid crystal composition and shaken for 1 minute using a shaker. Next, MgSO ₄ that absorbed moisture from the liquid crystal composition was separated by using a syringe filter.

MgSO ₄ The separated liquid crystal composition was applied on the alignment layer to a thickness of 2 μm after drying, and dried with hot air in a drying oven at 80° C. for 2 minutes. Thereafter, a liquid crystal film was prepared by curing by irradiating unpolarized ultraviolet rays with a high-pressure mercury lamp (80 w/cm). The ultraviolet rays are ultraviolet rays of about 150 nm to 350 nm, and are irradiated with a total amount of light of 50 mJ/cm ² to 5000 mJ/cm ² . The manufactured liquid crystal film is a laminated optical film including a polycarbonate film, an alignment film formed on the film, and a liquid crystal layer formed on the alignment film.

comparative example One.

20 g of photo-alignable polymer 5-norbornene-2-methyl-(4-methoxy cinnamate), 20 g of dipentaerythritol hexaacrylate as a reactive compound, and a photoinitiator (Irgacure OXE02, Ciba-Geigy Co., Ltd. (Switzerland) F) 5 g of cyclopentanone was dissolved in 980 g of cyclopentanone to prepare an alignment layer composition, and the alignment layer composition was applied on a polycarbonate film to a thickness of about 1,000 Å after drying, and then in a drying oven at 80° C. for 2 minutes dried in hot air. After drying, a high-pressure mercury lamp is used as a light source, and linearly polarized ultraviolet rays are irradiated in a direction perpendicular to the traveling direction of the film through a wire grid polarizer (manufactured by Moxtek) at a light amount of 150 mJ/cm ² to impart orientation. An alignment layer was prepared.

A polymerizable liquid crystal compound capable of plane alignment and having reverse wavelength dispersion (manufactured by DIC) UCL-R17 mixture was added to toluene as a solvent so that the solid content was 35 parts by weight based on 100 parts by weight of the total composition (solvent + UCL-R17 mixture) A liquid crystal composition was prepared by dissolution.

The liquid crystal composition was applied on the alignment layer to a thickness of 2 μm after drying, and dried with hot air in a drying oven at 80° C. for 2 minutes. Thereafter, a liquid crystal film was prepared by curing by irradiating unpolarized ultraviolet rays with a high-pressure mercury lamp (80 w/cm). The ultraviolet rays are ultraviolet rays of about 150 nm to 350 nm, and are irradiated with a total amount of light of 50 mJ/cm ² to 5000 mJ/cm ² . The manufactured liquid crystal film is a laminated optical film including a polycarbonate film, an alignment film formed on the film, and a liquid crystal layer formed on the alignment film.

evaluation example 1. High temperature durability evaluation

For Examples and Comparative Examples, the initial retardation value and the retardation value after heating were measured, and the rate of change of the retardation value was measured according to Equation 5, and the results are shown in Table 1 below. The in-plane retardation was measured for light with a wavelength of 550 nm using an Axoscan device (manufactured by Axomatrics) capable of measuring 16 Muller matrices. Using Axoscan equipment, 16 Muller matrices were obtained according to the manufacturer's manual, and phase differences were extracted through them.

[Formula 5]

ΔRin=(1-Rin ₂ /Rin ₁ ) × 100

ΔRin is the in-plane retardation change rate after heating, Rin ₁ is the initial in-plane retardation value at 25°C, and Rin ₂ is the in-plane retardation value after heating at 80°C for 300 hours.

As shown in Table 1, Comparative Example 1 without using a moisture absorbent has a phase difference change rate of -2.5% after heating for 300 hours, and Example 1 in which the moisture content is reduced using a moisture absorbent has a phase difference change rate after heating for 300 hours. showed -1.1%. From this, it can be confirmed that Example 1 has excellent high-temperature durability compared to Comparative Example 1.

Phase difference value over time (nm) 0hr 300hrs Change rate (%) Comparative Example 1 161.7 157.6 -2.5 Example 1 153.2 151.6 -1.1

Claims (15)

adding a water absorbent to a liquid crystal composition containing a polymerizable liquid crystal compound and a solvent to reduce water content in the liquid crystal composition;
A method for manufacturing a liquid crystal film comprising the step of applying the liquid crystal composition having a reduced water content on a base film,
An alignment layer is formed on one surface of the base film,
The liquid crystal composition is applied to the surface of the base film on which the alignment layer is formed,
The method of manufacturing a liquid crystal film in which the alignment film has an alignment ability with respect to an adjacent layer of a liquid crystal composition. The method of claim 1 , wherein the liquid crystal composition comprises 20 to 50 parts by weight of the polymerizable liquid crystal compound based on solid content, based on 100 parts by weight of the solvent. The method of claim 1, wherein the polymerizable liquid crystal compound satisfies Equation 1 below:
[Formula 1]
R(450)/R(550) < R(650)/R(550)
In Equation 1, R(λ) means an in-plane retardation of light having a wavelength of λ nm. The method of claim 1, wherein the moisture absorbent is silica gel, zeolite, CaO, BaO, MgSO ₄ , Mg(ClO ₄ ) ₂ , MgO, P ₂ O ₅ , Al ₂ O ₃ , CaH ₂ , NaH, LiAlH ₄ , CaSO ₄ , Na ₂ SO ₄ , CaCO ₃ , K ₂ CO ₃ , CaCl ₂ , 4A and 3A molecular sieves, Ba(ClO ₄ ) ₂ , cross-linked poly(acrylic acid) and poly(acrylic acid) selected from the group consisting of A method for producing a liquid crystal film comprising at least one kind. The method of claim 1, wherein the water absorbent is added in an amount of 3 to 7 parts by weight based on 100 parts by weight of the liquid crystal composition. The method of claim 1 , further comprising shaking the liquid crystal composition to which the moisture absorbent is added for 30 seconds to 3 minutes. The method of claim 1 , further comprising separating the water absorbent from the liquid crystal composition. delete The method of claim 1 , wherein the liquid crystal composition is applied to a thickness of 1 μm to 3 μm after drying. delete The method of claim 1 , further comprising drying the layer of the liquid crystal composition applied on the base film with hot air. The method of claim 11 , wherein the hot air drying is performed within a range of 70° C. to 90° C. The method of claim 11 , wherein the hot air drying is performed for 1 minute to 5 minutes. The method of claim 1 , further comprising irradiating ultraviolet rays to the layer of the liquid crystal composition applied on the base film. The method of claim 1 , wherein the liquid crystal film manufactured according to the manufacturing method has an absolute value of retardation change rate (ΔRin) of 2.0% or less calculated by Equation 5 below:
[Formula 5]
ΔRin = (1-Rin ₂ /Rin ₁ ) × 100
ΔRin is the in-plane retardation change rate after heating, Rin ₁ is the initial in-plane retardation value, and Rin ₂ is the in-plane retardation value after heating at 80 °C for 300 hours.