KR101265310B1 - Composition for Alignment Film, A Method for Preparing an Liquid Crystal Alignment File Using the Same, Optical Anisotropic Film, Polarizing Plate and Liquid Crystal Display Comprising the Optical Anisotropic Film - Google Patents

Abstract

The present invention, when used in a high temperature and humidity environment when using a cyclo olefin-based stretch film (COP) as a substrate instead of triacetyl cellulose (TAC) used as a substrate for a conventional optical film that the optical properties are significantly lowered, the substrate and An alignment film composition having excellent heat resistance and moisture resistance as well as adhesion to a liquid crystal layer, and a method for preparing a liquid crystal alignment film using the same, an optically anisotropic film including a liquid crystal alignment film prepared therefrom, and a polarizing plate and a liquid crystal display device including the same. According to the present invention, 0.1 to 10% by weight of polyvinyl alcohol (PVA), 0.01 to 2% by weight of crosslinking agent, 0.05 to 5% by weight of polyfunctional acrylic monomer, 0.01 to 2% by weight of compatibilizer, There is provided an alignment film composition for cycloolefin-based polymer substrates containing 0.01 to 5% by weight of a photoinitiator and a mixed solvent of balance of water and alcohol. Moreover, the liquid crystal aligning film manufacturing method formed by apply | coating, drying, hardening | curing and giving an orientation to a COP base material; An optically anisotropic film comprising a COP substrate, an alignment film on a COP substrate, and a liquid crystal layer formed on the alignment film; And a polarizing plate including the optically anisotropic film of the present invention and a liquid crystal display including the same. The alignment film composition of the present invention does not require a separate separation and purification process. In addition, the alignment film formed of the alignment film composition of the present invention not only has excellent adhesion between the cycloolefin (COP) substrate, the alignment film, and the alignment film and the liquid crystal layer, but also has excellent optical properties, heat resistance and moisture resistance, particularly in high temperature and high humidity environments. , Optical properties, heat resistance and moisture resistance.

Alignment film, COP base material, adhesiveness, acrylate, moisture resistance, heat resistance

Description

Composition for alignment film, A method for preparing an liquid crystal alignment file using the same, optical anisotropic film, polarizing Plate and Liquid Crystal Display Comprising the Optical Anisotropic Film}

The present invention relates to an alignment film composition having excellent adhesion, heat resistance, and moisture resistance, a method of manufacturing a liquid crystal alignment film using the same, an optically anisotropic film including a liquid crystal alignment film prepared therefrom, a polarizing plate including the same, and a liquid crystal display device including the polarizing plate. will be. More specifically, when using a cyclo olefin-based stretched film (COP) as a substrate instead of the triacetyl cellulose (TAC) used as a substrate for a conventional optical film that the optical properties are significantly reduced when used in a high temperature and high humidity environment, An alignment film composition having excellent heat resistance and moisture resistance as well as adhesion to a substrate and a liquid crystal layer, a method of manufacturing a liquid crystal alignment film using the same, an optically anisotropic film including a liquid crystal alignment film prepared therefrom, and a polarizing plate including the same, and a polarizing plate including the same. It relates to a liquid crystal display device comprising a.

A liquid crystal display device (LCD) is a display device that expresses pixels using a principle of selectively passing light by a change in polarization action according to an arrangement of liquid crystals positioned between polarizers.

When the liquid crystal display device is used only as a polarizer including only a liquid crystal and a polarizing element, the brightness or contrast is remarkably lowered or the light leakage is observed when the liquid crystal is observed at various viewing angles other than when the liquid crystal is viewed from the front face perpendicular to the liquid crystal screen. There is a problem that an image occurs. Therefore, such a polarizing plate generally includes an optical compensation film such as a retardation film or a viewing angle compensation film in addition to the polarizing element, or these films are generally attached to a panel separately. As such, an optical film such as a retardation film and a viewing angle compensation film is inserted between the polarizing plate and the liquid crystal display device to reduce color change of the liquid crystal display (LCD) device, to enlarge the viewing angle, and to improve luminance.

The optical film for use in this application is a liquid crystal film (optical anisotropic film) made by applying a polymerizable liquid crystal compound on a stretched film and a plastic substrate to which optical polymer is extended by extending a polymer film and applying it to a plastic substrate. Proposed. The stretched film and the liquid crystal film used as the optical film have optical anisotropy, and in particular, the liquid crystal film may have various types of optical properties that are difficult to realize in the stretched film. That is, the liquid crystal may be divided into disc-type liquid crystal and rod-type liquid crystal according to the shape of the liquid crystal molecules. Among them, the liquid crystal in particular is planar, homeotropic, and tilted. Because of the various orientation forms such as), splay, and cholesteric, the resulting optical properties are much more diverse and unique than stretched films. In addition, by applying a polymerizable liquid crystal compound directly on the stretched film to add the alignment characteristics of the above-mentioned various liquid crystals, the protective film of the polarizer and the stretched film alone can perform the role of an optical compensation film difficult to implement. Therefore, the demand for liquid crystal film is increasing.

In general, the liquid crystal film is coated with an alignment layer composition for forming a liquid crystal alignment layer on a plastic substrate, and then dried and cured to form an alignment layer, and then rubbed again to impart orientation, and then apply, dry and cure a polymerizable liquid crystal compound thereon. It is generally manufactured in such a way that it is fixed. Since the alignment layer has insufficient adhesion between the liquid crystal layer and the substrate, the liquid crystal layer may be peeled off from the alignment layer, and in particular, a problem such as a phase difference change due to shrinkage or shrinkage of the liquid crystal layer may occur in a high temperature and high humidity environment. Excellent adhesion, heat resistance and moisture resistance of the alignment film, in particular, adhesion between the liquid crystal layer and the substrate is maintained even in a humid environment, and excellent heat resistance and moisture resistance that can prevent deformation of the liquid crystal layer are required.

Background Art Conventionally, polyimide has been widely known as an alignment film composition for forming the alignment film, and recently polyvinyl alcohol has been widely used. However, when the polyvinyl alcohol is used as the alignment layer composition, the adhesive strength with the liquid crystal layer (liquid crystal film) is insufficient, so that the liquid crystal layer (liquid crystal film) is peeled off as described above, or the liquid crystal layer (liquid crystal film) in a high temperature and high humidity environment. Problems such as shrinkage may occur and are not suitable.

In addition, a method of using modified polyvinyl alcohol modified with polyvinyl alcohol to improve adhesion with a liquid crystal film has been proposed in Japanese Patent Laid-Open No. 2002-62426 and Japanese Patent Laid-Open No. 7-179125. It cannot be used as a coating liquid, but can be used as an alignment film composition after additionally separating and purifying the modified polyvinyl alcohol.

In addition, the alignment film is usually formed on a plastic substrate, but even if the alignment film composition prepared by the process of the patent application, there is no limit to the type of substrate that can be used to effectively adhere to a substrate such as triacetyl cellulose (TAC) However, the adhesion is very poor for substrates such as cycloolefin polymers (COPs).

That is, the triacetyl cellulose base material is widely used as a protective film of the polarizing plate polarizer and the base material of the alignment layer, but due to the high hygroscopicity, there is a problem in that light leakage occurs in a high temperature and high humidity environment, and durability is poor, such as lowering the degree of polarization. . Therefore, various substrates have been proposed to replace them, and among them, cycloolefin polymers are representative examples.

However, in the case of using the cycloolefin-based substrate, problems such as separation of the alignment layer may occur due to poor adhesiveness when using the above-described conventional alignment layer composition. In addition, the conventional alignment layer may include a liquid crystal layer and / or a COP. Since the adhesive force with the substrate is not sufficient, problems such as phase difference change due to peeling and / or shrinkage of the liquid crystal layer may occur, particularly in a high temperature and high humidity environment. Therefore, there is a need for an alignment film composition having excellent adhesion, heat resistance and moisture resistance, particularly heat resistance and moisture resistance that can maintain excellent adhesion with the liquid crystal layer and the substrate even in a humid environment and can prevent deformation of the liquid crystal layer.

Accordingly, an object of the present invention is to solve the above-described problems of the prior art, and does not require a separate separation and purification process, and can directly form an alignment layer composition on a plastic substrate to form an alignment layer. It is providing the composition for alignment films excellent in adhesiveness, heat resistance, and moisture resistance between an alignment film and a liquid crystal layer.

Another object of the present invention is to provide an alignment film composition excellent in adhesiveness, heat resistance and moisture resistance of the present invention, and a method for producing a liquid crystal alignment film using a cycloolefin-based substrate.

Still another object of the present invention is to provide an alignment film composition having excellent adhesion, heat resistance, and moisture resistance of the present invention, and an optically anisotropic film having excellent adhesion, heat resistance, and moisture resistance made from a cycloolefin based substrate.

Furthermore, another object of the present invention is to provide a polarizing plate including an optically anisotropic film having excellent adhesion, heat resistance, and moisture resistance, and a liquid crystal display including the polarizing plate.

According to the first aspect of the present invention,

0.1 to 10% by weight of polyvinyl alcohol (PVA), 0.01 to 2% by weight of crosslinking agent, 0.05 to 5% by weight of polyfunctional acrylic monomer, 0.01 to 2% by weight of compatibilizer, 0.01 to 5% by weight of photoinitiator An alignment film composition comprising% and a balance solvent of water and alcohol is provided.

According to the second aspect of the present invention,

0.1 to 10% by weight of polyvinyl alcohol (PVA), 0.01 to 2% by weight of crosslinking agent, 0.05 to 5% by weight of polyfunctional acrylic monomer, 0.01 to 2% by weight of compatibilizer based on the total weight of the alignment film composition on the cycloolefin polymer substrate Applying an alignment layer composition comprising 0.01 to 5% by weight of a photoinitiator and a mixed solvent of the residual water and alcohol;

Drying the applied alignment layer composition;

Curing the dried alignment layer composition; And

There is provided a liquid crystal aligning film manufacturing method comprising the step of imparting orientation to the cured alignment film composition.

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According to the third aspect of the present invention,

Cyclo olefin-based polymer substrates;

0.1 to 10% by weight of polyvinyl alcohol (PVA), 0.01 to 2% by weight of crosslinking agent, 0.05 to 5% by weight of polyfunctional acrylic monomer, 0.01 to 2 of compatibilizer based on the total weight of the alignment film composition on the cycloolefin polymer substrate An alignment film formed of an alignment film composition comprising a weight%, a photoinitiator 0.01 to 5% by weight and a balance solvent and a mixed solvent of water and an alcohol, and having an orientation imparted thereto; And

An optically anisotropic film comprising a liquid crystal layer formed on the alignment film is provided.

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According to the fourth aspect of the present invention,

The polarizing plate containing the optically anisotropic film of the said invention is provided.

According to the fifth aspect of the present invention,

A liquid crystal display device including the polarizing plate of the present invention is provided.

The alignment film composition of the present invention does not require a separate separation and purification process. In addition, the alignment film formed of the alignment film composition of the present invention is excellent in adhesion between the cycloolefin-based (COP) substrate, the alignment film, and the alignment film and the liquid crystal layer, regardless of whether or not the substrate surface is treated separately, as well as optical properties, heat resistance and moisture resistance. In particular, it has excellent adhesion, optical properties, heat resistance and moisture resistance in a high temperature and high humidity environment. Therefore, peeling and shrinkage of the liquid crystal layer are prevented and excellent optical properties are exhibited.

Furthermore, when the alignment film composition of the present invention is applied to a COP substrate to form an alignment film, a separate pretreatment is not required for the substrate, and the adhesive, optical properties, An alignment film excellent in heat resistance and moisture resistance can be formed. In addition, the optically anisotropic film including the alignment film and the liquid crystal layer formed of the alignment film composition of the present invention can be used as a retardation film for a liquid crystal display device, a protective film of the polarizer.

Hereinafter, the present invention will be described in more detail.

1. Alignment film composition

The inventors of the present invention have studied to overcome the above-mentioned problems of the prior art and to develop an alignment film composition having a new composition that meets the object of the present invention. As a result, a crosslinking reaction with polyvinyl alcohol, a polyfunctional acrylic monomer, and polyvinyl alcohol It was found that compositions prepared by dissolving these possible specific crosslinking agents, compatibilizers and photoinitiators in a mixed solvent of water and alcohol have not only good adhesion to cycloolefin-based polymer (COP) substrates and liquid crystal layers, but also heat and moisture resistance. And the present invention.

As used herein, the term 'alignment film composition' refers to a material for forming an alignment film, which is a material for forming an alignment film, which may be prepared as an alignment film having a performance intended in the present invention when it is polymerized.

The alignment film composition of the present invention is based on the total weight of the alignment film composition of 0.1 to 10% by weight of polyvinyl alcohol (PVA), 0.01 to 2% by weight of crosslinking agent, 0.05 to 5% by weight of polyfunctional acrylic monomer, 0.01 to 2% by weight of compatibilizer 0.01 to 5% by weight of the photoinitiator, and the balance solvent and mixed solvent of water.

The polyvinyl alcohol is a main material for forming the alignment layer, and the polyvinyl alcohol is not particularly limited, but polyvinyl alcohol having a weight average molecular weight (Mw) of 85,000 to 146,000 is preferred, and in particular, the amount of water is 96% or less. Decomposed is preferred. The weight average molecular weight of the polyvinyl alcohol has some influence on the adhesive properties, but does not show a large difference in the performance of the alignment layer, and Mw of 85,000 to 146,000 is commonly used. In addition, polyvinyl alcohol is generally used at least 80% or more hydrolyzed, but exceeding 96% is not preferable because it adversely affects the adhesion performance and orientation characteristics of the alignment film, hydrolysis to 96% or less It is preferable to use what is used. The lower limit of the degree of hydrolysis does not need to be specifically determined, but the degree of hydrolysis of polyvinyl alcohol that can be generally obtained is the lowest at 80%.

The content of the polyvinyl alcohol is 0.1 to 10% by weight, preferably 0.1 to 5% by weight based on the total weight of the alignment layer composition. If the content of the polyvinyl alcohol is less than 0.1% by weight, it is not easy to control the thickness of the alignment film. If the content of the polyvinyl alcohol exceeds 10% by weight, the uniform coating property cannot be maintained due to the increase in viscosity, and the thickness of the film is excessive to provide a good alignment film. Hard to get

In the liquid crystal aligning film composition according to the present invention, the crosslinking agent is additionally formed between the crosslinking agent and the polyvinyl alcohol by a crosslinking agent in addition to the crosslinking reaction of the polyfunctional acrylic monomer with the polyfunctional acrylic monomer and the polyvinyl alcohol and / or the polyfunctional acrylic monomer itself. It acts to induce crosslinking reaction. Examples of the crosslinking agent include, but are not limited to, aldehydes, dialdehydes, isocyanates, and the like. Examples of aldehydes or dialdehydes include, but are not limited to, acrylaldehyde, oxalaldehyde, 2-methylacrylaldehyde, 2-oxopropanal, glutaraldehyde and the like. Examples of isocyanates include, but are not limited to, 2-isocyanatoethyl 2-methylacrylate, 1,4-diisocyanatobutane, 1,4-diisocyanatobenzene, and 1,3-diisocyanatobenzene Etc. can be mentioned. The crosslinking agents may be used alone or in a mixture of two or more thereof.

The content of the crosslinking agent is 0.01 to 2% by weight, preferably 0.01 to 1% by weight based on the total weight of the alignment film composition. If the content of the crosslinking agent is less than 0.01% by weight, it is not preferable because a sufficient crosslinking reaction may not be induced, and thus the moisture resistance is inhibited. If the content of the crosslinking agent is more than 2% by weight, the heat resistance and moisture resistance are improved. Although there is a tendency, the viscosity of the alignment layer composition tends to increase with time, resulting in poor solution stability and uniform coating property, and in particular, lowering the alignment force of the liquid crystal after rubbing.

The polyfunctional acrylic monomer is an important component for preparing the alignment film having the advantageous effect of the present invention by assisting the polyvinyl alcohol by crosslinking reaction with the polyvinyl alcohol or the polyfunctional acrylic monomer itself upon ultraviolet irradiation. As the polyfunctional acrylic monomer, one or two or more kinds of polyfunctional acrylic monomers having 2 to 6 acrylic groups may be used, and examples of such polyfunctional acrylic monomers are not limited thereto, but triacrylate. (Particularly pentaerythritol triacrylate (PETA)), tetraacrylate (particularly pentaerythritol tetraacrylate (PETA)) or hexaacrylate (particularly di Pentaerythritol hexaacrylate (DIPentaerthritol hexaacrylate, DPHA) and the like are preferable. They are not necessarily used only one kind, but may be used in combination of two or more kinds.

The content of the multifunctional acrylic monomer may be 0.05 to 5% by weight, preferably 0.05 to 2.5% by weight based on the total weight of the alignment layer composition. When the content of the polyfunctional acrylic monomer is less than 0.05% by weight, the interlayer adhesion between the alignment film and the liquid crystal film or the substrate such as the cycloolefin polymer (COP) may be poor, resulting in a problem that the alignment film or the liquid crystal film is peeled off. If it exceeds 5% by weight, the compatibility of the polyfunctional acrylic monomer with the polyvinyl alcohol worsens, and these may precipitate after the alignment film is applied, and in particular, the orientation of the liquid crystal is greatly reduced.

In the liquid crystal aligning film composition according to the present invention, the compatibilizer serves to improve the compatibility of the polyvinyl alcohol and the polyfunctional acrylic monomer. Examples of compatibilizers include, but are not limited to, poly (4-vinylphenol). The molecular weight of the compatibilizer is not particularly limited.

The content of the compatibilizer is not particularly limited, but may be 0.01 to 2% by weight, preferably 0.01 to 1.5% by weight based on the total weight of the alignment layer composition. If the content of the compatibilizer is less than 0.01% by weight, the compatibility of the polyvinyl alcohol and the polyfunctional acrylic monomer is not sufficient, and there is a problem in that the acrylic monomer is precipitated after coating and drying. The property is lowered, and in particular, the orientation of the liquid crystal is lowered.

In order to form the alignment film composition applied on the substrate to the alignment film, a process of curing the alignment film composition is required. Curing of the alignment layer composition may be accomplished by photocuring (particularly UV curing) the alignment layer having a solvent evaporated by drying after drying the alignment layer composition. For this purpose, it is necessary to include a photo initiator. In the liquid crystal aligning film composition according to the present invention, any one of the photoinitiator can be used as long as it can induce a radical reaction, and since a mixed solvent of water and alcohol is used as the solvent, it is more preferable to be water-soluble. Examples of the photoinitiator include, but are not limited to, Igacure 2959 (IRGACURE 2959, 2-hydroxy-1- [4- (2-hydroxyethoxy) phenyl] supplied by Ciba-Geigy. -2-methyl-1-propaneone), Igacure 500 (IRGACURE 500, 1-hydroxy-cyclohexyl-phenyl-ketone and benzophenone), Igacure 754 (IRGACURE 754, oxy-phenyl-acetic acid 2- [2 Oxo-2 phenyl-acetoxy-ethoxy] -ethyl ester and oxy-phenyl acetic 2- [2-hydrocy-ethoxy] -ethyl ester).

The content of the photoinitiator is more preferably 0.01 to 5% by weight, preferably 0.01 to 2% by weight based on the total weight of the alignment film composition. When the photoinitiator content is less than 0.01% by weight, the crosslinking reaction effect by the multifunctional acrylic monomer cannot be expected, and when it exceeds 5% by weight, the orientation of the liquid crystal is significantly reduced.

In the alignment film composition according to the present invention, it is preferable that the polyvinyl alcohol, the crosslinking agent, the polyfunctional acrylic monomer, the compatibilizer and the photoinitiator constituting the alignment film composition are dissolved in a mixed solvent of water and alcohol to form the alignment film composition solution. .

As the alcohol in the mixed solvent, it is preferable to use methyl alcohol, ethyl alcohol, isopropyl alcohol and the like. It is preferable to dissolve polyvinyl alcohol, crosslinking agent, polyfunctional acryl monomer, compatibilizer and photoinitiator by mixing water: alcohol in a mixed solvent in a 40:60 to 50:50 weight ratio, especially in case of methyl alcohol or ethyl alcohol. Most preferably, the ratio is 41:59 by weight, and in the case of isopropyl alcohol, the ratio is 40:60 by weight.

The alignment layer composition of the present invention may be prepared by a conventional method for producing a composition known until now. However, to exemplify a more effective method for preparing the alignment layer composition, a solution in which polyvinyl alcohol is dissolved in water at 150 ° C. and a crosslinking agent, a polyfunctional acrylic monomer, a compatibilizer and a photoinitiator in ethanol is prepared, and the two solutions are prepared. After mixing, the method of reheating to 150 degreeC is preferable. Although all the components constituting the alignment layer composition may be mixed at once, the mixing of all the components at once is not preferable because the polyvinyl alcohol and ethanol do not mix well, so the method is more preferable.

The alignment film composition according to the present invention is particularly applied to a cyclo olefin polymer (COP) substrate exhibits excellent adhesion, moisture resistance and heat resistance, the cycloolefin polymer substrate to which the alignment film composition of the present invention can be applied is particularly limited. It is to be understood that the invention includes any cyclo olefinic polymer substrate generally known in the art.

2. Manufacturing method of alignment film

In another embodiment of the present invention, after the alignment film composition of the present invention is applied to a cyclo olefin-based polymer substrate and dried to form a film, there is provided a method for producing an alignment film that cures the film formed on the substrate and imparts orientation. .

In preparing the alignment film using the alignment film composition according to the present invention, a cyclo olefin-based polymer substrate may be used as the substrate, and in particular, the alignment film composition according to the present invention exhibits excellent adhesion to the COP substrate. First, the alignment film composition of this invention is apply | coated on a COP base material. The alignment film composition of the present invention on the cycloolefin polymer substrate may be applied by any coating method generally known in the art, and the coating method is not particularly limited.

It is preferable to apply | coat the said orientation film composition uniformly to thickness of about 800-2000 GPa on a base material. If the thickness is less than 800 GPa, it is not preferable in that an orientation defect due to surface abrasion occurs when rubbing the alignment layer. If the thickness is more than 2000 GPa, since sufficient crosslinking reaction is not induced, the adhesiveness and moisture resistance are not preferable.

After applying the alignment film composition on the substrate, it can be dried for at least 30 seconds at 70 ~ 150 ℃ to remove the remaining solvent. If the drying temperature is less than 70 ℃ may not be sufficiently dried, stains may occur easily, in particular, the reaction between the polyvinyl alcohol and the crosslinking agent is not sufficient, causing a decrease in the heat resistance and moisture resistance of the one-piece optically anisotropic film (liquid crystal film) to be produced later The orientation of the liquid crystal may be lowered due to the influence of the remaining crosslinking agent which remains unreacted. It is not preferable that the drying temperature exceeds 150 ° C. as this may cause deformation of the substrate. The drying time may be dried during the time that the alignment film can be sufficiently dried in the above temperature range, and the drying time is not particularly limited. By drying for about 30 seconds, the remaining solvent can be removed and the alignment film can be sufficiently dried.

After drying to form a film, it is hardened by irradiating an ultraviolet-ray to a film. Ultraviolet irradiation can be performed in air | atmosphere or in the nitrogen atmosphere which interrupted oxygen in order to improve reaction efficiency. Typically ultraviolet irradiator may be used a medium or high pressure mercury ultraviolet lamp, or a metal halide lamp having an intensity of 80 w / cm or more. The radical reaction of the polyfunctional acrylic monomer by ultraviolet irradiation occurs in the presence of a photoinitiator that absorbs the wavelength in the ultraviolet region, and through this process, the alignment film and the substrate are formed by the crosslinking reaction between the polyvinyl alcohol, the crosslinking agent, and the polyfunctional acrylic monomer. Adhesiveness with and adhesion with the liquid crystal layer formed thereafter may be imparted. After the curing, the alignment film is completed by rubbing the coating to impart orientation.

3. optically anisotropic film

In another embodiment of the present invention, there is provided an optically anisotropic film comprising the COP substrate, the alignment film given the alignment formed on the COP substrate and the liquid crystal layer formed on the alignment film. The optically anisotropic film of the present invention can be prepared by applying and drying a polymerizable liquid crystal compound solution to the oriented aligned oriented film and fixing the liquid crystal compound by irradiating with ultraviolet rays. 1 is a side cross-sectional view of an optically anisotropic film according to the present invention.

As the polymerizable liquid crystal compound, a nematic or cholesteric liquid crystal which polymerizes with a surrounding liquid crystal monomer by light to form a liquid crystal polymer may be used. Generally, the polymerizable liquid crystal compound is applied in an isotropic state on an alignment film fixed by applying an alignment film composition to an alignment-oriented plastic substrate or a plastic substrate, and then subjected to a nematic regularity or cholesteric rule by polymerization during drying and curing. There is a characteristic that the phase changes to a liquid crystal having the property and is oriented in a specific direction, so that the orientation does not change even when other layers are laminated.

In the optically anisotropic film according to the present invention, as the polymerizable liquid crystal compound, any polymerizable liquid crystal compound generally known in the art may be used as a material having an acrylate group polymerizable by photoreaction. Although not limited, nematic or cholesteric liquid crystal phases may be used at room temperature or at high temperature, such as cyano biphenyl, cyano phenyl cyclohexane, cyano phenyl ester, benzoic phenyl ester, and phenyl pyrimidine acrylates. The low molecular liquid crystal shown is mentioned. These materials may be used alone or in a mixture of two or more.

The liquid crystal compound solution may be prepared by dissolving a polymerizable liquid crystal compound and a photoinitiator in an organic solvent. The content of the polymerizable liquid crystal compound in the liquid crystal compound solution is not particularly limited, but may be 5 to 70 parts by weight, preferably 5 to 50 parts by weight, per 100 parts by weight of the liquid crystal compound solution. If the content of the polymerizable liquid crystal compound is less than 5 parts by weight, staining may be intensified. If the content of the polymerizable liquid crystal compound is greater than 70 parts by weight, the amount of the solvent may be small, resulting in precipitation of the polymerizable liquid crystal compound.

The liquid crystal compound solution may contain a small amount of photoinitiator. Examples of photoinitiators include, but are not limited to, Igacure 907. The content of the photoinitiator is preferably 3 to 10 parts by weight per 100 parts by weight of the polymerizable liquid crystal compound in the liquid crystal compound solution. When the content of the photoinitiator is less than 3 parts by weight, the liquid crystal orientation may be changed under the influence of the photoinitiator if the amount is greater than 10 parts by weight without sufficient curing during ultraviolet irradiation.

In addition to the photoinitiator, chiral agents, surfactants, polymerizable monomers, polymers, and the like may be added to the liquid crystal compound solution as long as they do not interfere with liquid crystal alignment.

Examples of the organic solvent in preparing the liquid crystal compound solution include, but are not limited to, halogenated hydrocarbons such as chloroform, tetrachloroethane, trichloroethylene, tetrachloroethylene and chlorobenzene; Aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene and 1,2-dimethoxybenzene; Ketones such as acetone, methyl ethyl ketone, cyclohexanone and cyclopentanone; Alcohols such as isopropyl alcohol and n-butanol; Cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, and the like; and these may be used alone or in a mixture of two or more thereof.

The liquid crystal compound solution is applied onto the alignment layer provided with the alignment and then dried. The coating can be carried out by any method known in the art, and the coating method and the coating thickness and the like are common in the art and are not limited thereto. It is preferable to dry at least 1 minute at 25-120 degreeC. The drying temperature may be an important factor in the alignment position of the liquid crystal, and when it is out of the above temperature range, the drying temperature may affect the alignment of the liquid crystal, and stains may occur. The drying time may be dried for a time in which the liquid crystal layer can be sufficiently dried in the drying temperature range, and the drying time is not particularly limited. By drying for about 1 minute or more, the remaining solvent can be removed and the alignment film can be sufficiently dried.

After drying of the liquid crystal compound solution, the liquid crystal layer oriented on the alignment film is fixed by polymerization and curing through ultraviolet irradiation. At this time, curing by polymerization is carried out in the presence of a photoinitiator absorbing the wavelength of the ultraviolet region. Ultraviolet irradiation can be performed in air | atmosphere or in the nitrogen atmosphere which interrupted oxygen in order to improve reaction efficiency. Typically ultraviolet irradiator may be used a medium or high pressure mercury ultraviolet lamp, or a metal halide lamp having an intensity of 80 w / cm or more. In the ultraviolet irradiation, a cold mirror or other cooling device may be provided between the substrate and the ultraviolet lamp so that the surface temperature of the liquid crystal layer is within a temperature range having a liquid crystal state.

The optical film according to the present invention has the characteristics of optical anisotropy, and may be preferably used as an optical compensation member (for example, a retardation film, a protective film of a polarizing element) for a liquid crystal display device. More specifically, for example, but not limited to, Super Twist Nematic (STN) type LCD, Thin Film Transistor-Twisted Nematic (TFT-TN) type LCD, Vertical Alignment (VA) type LCD, In-Plane (IPS) type Retardation films such as Switching type LCD; Half wave plate; Quarter wave plate; Reverse wavelength dispersion film; Optical compensation films; Color filters; Laminated film with a polarizing plate; It can be used as a polarizing plate compensation film or the like.

4. Integrated polarizer

In still another embodiment of the present invention, an integrated polarizing plate including one or more polarizing elements and an optically anisotropic film according to the present invention as a protective film is provided on one surface of the polarizing element. In the integrated polarizer provided in one embodiment according to the present invention, the optically anisotropic film according to the present invention includes a COP substrate and serves as a retardation film due to an alignment layer and a liquid crystal layer as well as a protective film. Hereinafter, in the present specification, 'polarizing device' means a state not including a protective film, and 'polarizing plate' means a state including a polarizing element and a protective film.

2A and 2B show an integrated polarizer according to the present invention. 2A and 2B, it may be laminated with a protective film, a polarizer, and an optically anisotropic film (which serves as a protective film and a retardation film in a polarizing plate) generally used from the bottom of an integrated polarizing plate.

The commonly used protective film may be any one used as a polarizer protective film in the art, but is not limited thereto, for example, triacetate cellulose (TAC) film, ring opening metathesis polynorbornene-based films made of polymerization (ROMP), ring opening metathesis polymerization followed by hydrogenation (HROMP) polymer films, polyester films, or addition polymerizations obtained by hydrogenation again to ring-opened polymerized cyclic olefin-based polymers. Polynorbornene-based film and the like can be used. In addition, a film made of a transparent polymer material may be used as the protective film, but is not limited thereto. Any film used as a protective film in the art may be used.

As the polarizer, a film made of polyvinyl alcohol (PVA) containing iodine or dichroic dye may be used. The polarizer may be manufactured by dyeing iodine or dichroic dye on the PVA film, but the polarizer and its manufacturing method are not particularly limited, and are manufactured by a polarizer and a polarizer manufacturing method generally known in the art. Any polarizer can be used.

In the integrated polarizing plate of the present invention, a conventional protective film or an optically anisotropic film according to the present invention (hereinafter, the protective film and the optically anisotropic film together are referred to as a 'film') the polarizing element by any method known in the art Can be laminated. For example, the lamination of the film and the polarizer may be performed by an adhesive method using an adhesive. For example, first, an adhesive is coated on a surface of a film or PVA film which is a polarizer using a roll coater, gravure coater, bar coater, knife coater or capillary coater. Before the adhesive is completely dried, the film and the polarizer are laminated by heating or pressing at room temperature with a lamination roll. In the case of using a hot melt adhesive, a hot press roll should be used.

Adhesives that can be used when laminating the film and the polarizer include one-component or two-component PVA adhesives, polyurethane adhesives, epoxy adhesives, styrene butadiene rubber (SBR) adhesives, or hot melt adhesives. Any adhesive known to be generally applicable in the art may be used. When using a polyurethane adhesive, it is preferable to use the polyurethane adhesive manufactured using the aliphatic isocyanate type compound which does not yellow by light. When using one-component or two-component dry laminate adhesives or adhesives with relatively low reactivity between isocyanates and hydroxyl groups, a solution-type adhesive diluted with an acetate solvent, a ketone solvent, an ether solvent, or an aromatic solvent may be used. Can also be used. In this case, it is preferable to use an adhesive having a low viscosity of 5,000 cps or less in consideration of the adhesion between the film and the polarizing element and the optical characteristics of the polarizing plate. It is preferable that the adhesives have excellent storage stability and have a light transmittance of 90% or more at 400 to 800 nm.

A tackifier can also be used if it can exert sufficient adhesive force. It is preferable that the pressure-sensitive adhesive improves the mechanical strength to the level of the adhesive due to sufficient curing by heat or ultraviolet rays after lamination, and the interface adhesive force is also large, so that the pressure-sensitive adhesive force does not peel off without breaking of either film to which the pressure-sensitive adhesive is attached. desirable.

Specific examples of the pressure-sensitive adhesive that can be used include, but are not limited to, natural rubber, synthetic rubber or elastomer, vinyl chloride / vinyl acetate copolymer, polyvinyl alkyl ether, polyacrylate, or modified polyolefin-based pressure-sensitive adhesive having excellent optical transparency, and isocyanate. Curable adhesive which added hardening agents, such as these, is mentioned.

5. LCD Display

In still another embodiment of the present invention, there is provided a liquid crystal display including one or two or more polarizing plates according to the present invention.

A liquid crystal display device generally includes a liquid crystal cell and a polarizing plate on both sides of the liquid crystal cell, and in the structure of the conventional liquid crystal display device, one or two or more polarizing plates of item 4 according to the present invention may be used instead of the conventional polarizing plate. have. Although not limited to this, as an example of the liquid crystal display device according to the present invention, a liquid crystal display device including two polarizing plates is shown in FIG. 3.

In the following embodiments, the present invention will be described in more detail with reference to the accompanying drawings and data. However, it is necessary to note that the following examples are intended to illustrate and illustrate the present invention, but not to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the claims and matters reasonably interpreted therefrom.

< Example  1>

Polyvinyl alcohol, glutaraldehyde as a crosslinking agent, pentaerythritol triacrylate as a polyfunctional acrylic monomer, poly (4-vinylphenol) as a compatibilizer, and igcure 2959 as a photoinitiator in water and ethyl alcohol in a 50:50 weight ratio. The alignment film composition was prepared by dissolving at a concentration of 2% by weight, 0.1% by weight, 1% by weight, 0.25% by weight and 0.25% by weight, based on the total weight of the alignment film composition, in the mixed mixed solvent.

After drying the alignment layer composition on a cyclo olefin polymer (COP) substrate by applying a wire bar to a thickness of 1000Å, hot air dried in a 100 ℃ drying oven for 2 minutes and using a 80W / CM high pressure mercury lamp It was cured by ultraviolet irradiation once at a speed of 3 m / min, and a rubbing treatment was completed to impart orientation to the cured alignment film surface, thereby completing the alignment film.

95% by weight of a liquid crystal for O-Plate (a spread alignment liquid crystal compound consisting of Merck, cyano biphenyl, cyano phenyl cyclohexane and cyano phenyl ester) and Igacure 907 (a photoinitiator) Switzerland, Ciba-Geigy) polymerizable liquid crystal compound prepared by dissolving 5% by weight of solids mixed in toluene so that the solids content per 100 parts by weight of the total solution was 25 parts by weight. After drying hot air for 2 minutes in a drying oven at 60 ° C., a high-pressure mercury lamp of 80 W / CM intensity irradiated with a non-polarized ultraviolet light to cure the liquid crystal layer to prepare an optically anisotropic film.

Accordingly, as shown in FIG. 1, an optically anisotropic film laminated in the order of a COP substrate, a rubbed alignment film formed on the substrate, and a liquid crystal layer formed on the alignment film was obtained.

The bonding force between the layers, that is, the adhesion between the COP substrate and the alignment film and the alignment film and the liquid crystal film, was evaluated by a cross-cut test method defined by ASTM. Optical characteristics of the liquid crystal layer formed on the optical alignment layer were measured by quantitative retardation value according to the viewing angle using Axoscan (manufactured by Axomatrix Co., Ltd.), a birefringence measuring device, and the spreading alignment formed on the alignment layer manufactured by Example 1 in FIG. 4. A graph showing the phase difference distribution according to the viewing angle of the liquid crystal film is shown. As can be seen from the graph of FIG. 4, it was confirmed that the phase difference of the spreading orientation optically anisotropic film was well distributed as the viewing angle was changed.

After heat-resistance for 100 hours in a 100 ℃ drying oven, and after 100 hours in an oven at 80 ℃, 60% humidity, after the cross-cut test and Axoscan as described above The phase difference value was measured and evaluated for the degree of change.

< Example  2>

Except for using a liquid crystal for CLC (a twisted alignment liquid crystal compound consisting of Merck, cyano biphenyl, cyano phenyl cyclohexane, cyano phenyl ester, benzoic phenyl ester, and phenyl pyrimidine acrylate) Then, a twisted alignment optically anisotropic film (liquid crystal film) was produced in the same manner as in Example 1.

The transmittance of the twisted alignment liquid crystal layer formed on the alignment layer prepared in Example 2 was measured and the graph is shown in FIG. 3. The transmittance was measured using AXOSCAN in the same manner as the phase difference measuring method of Example 1. As can be seen from the graph of FIG. 5, it was confirmed that the liquid crystals were twisted in each wavelength band.

< Comparative example  1>

An optically anisotropic film was prepared in the same manner as in Example 1 except that an acetyl cellulose substrate was used instead of the cycloolefin polymer substrate.

< Comparative example  2>

An optically anisotropic film was prepared in the same manner as in Example 1 except that the crosslinking agent, the polyfunctional acrylic monomer and the photoinitiator were not used in the liquid crystal alignment film composition.

< Comparative example  3>

An optically anisotropic film was produced in the same manner as in Example 1 except that the crosslinking agent was not used in the liquid crystal alignment film composition.

(Check orientation and adhesion)

The orientation of the liquid crystal film according to Examples 1 to 2 and Comparative Examples 1 to 3 and the adhesion between the substrate and the alignment film and the adhesion between the alignment film and the liquid crystal layer were evaluated and the results are shown in Table 1 below. . Orientation evaluation was performed based on the case where orientation becomes (O) even if there exists a slight deviation from the case where orientation does not exist at all (X). Adhesiveness was judged by cross-cutting in the form of a checkerboard in the form of checkerboard on the surface of the liquid crystal film with a knife in accordance with ASTM standards, and then attached to the cellophane tape and detached from it. Where present, X indicates partial peeling or complete peeling between checkerboard patterns, and-indicates no test result.

[Table 1]

division Orientation Adhesive Substrate / Alignment Film Alignment Film / Liquid Crystal Layer Example Example 1 O O O Example 2 O O O Comparative example Comparative Example 1 O X O Comparative Example 2 O X X Comparative Example 3 O O O

(Check heat resistance and moisture resistance)

In order to evaluate the heat resistance and the moisture resistance of the optically anisotropic films of Examples 1, 2, Comparative Example 2 and Comparative Example 3, the heat resistance was left after leaving the optically anisotropic film in a temperature 100 ℃ oven for 100 hours, and After the silver anisotropic film was left for 100 hours in an oven maintained at 80 ° C. and 60% humidity, it was measured by evaluating the change in orientation (phase difference) and adhesiveness in the same manner as in the above orientation and adhesion test. It is shown in Tables 2 and 3, respectively.

Evaluation of the retardation change was based on 10% or more changes (X) and less than 10% (O) compared to the measured value at room temperature. It is judged as if it is stuck when the cellophane tape is attached and detached after cross-cutting in the same line shape, and O is completely stuck, X is partially peeled or completely separated between checkerboard patterns. In the case of peeling, and-indicate no experimental results.

TABLE 2 Optical Properties and Adhesion after Heat Treatment (Heat Resistance Evaluation)

division Orientation Adhesive Substrate / Alignment Film Alignment Film / Liquid Crystal Layer Example Example 1 O O O Example 2 O O O Comparative example Comparative Example 2 X X X Comparative Example 3 X X O

[Table 3] Optical properties and adhesion after high temperature and high humidity treatment (moisture resistance evaluation)

division Orientation Adhesive Substrate / Alignment Film Alignment Film / Liquid Crystal Layer Example Example 1 O O O Example 2 O O O Comparative example Comparative Example 2 X X X Comparative Example 3 X X O

As in the test results of Tables 1 to 3, the alignment film formed by using the alignment film composition provided by the present invention maintains excellent adhesion even after leaving under high temperature and high humidity to prevent peeling and shrinkage of the liquid crystal layer Thus, excellent optical properties (orientation) are exhibited. From this, it was confirmed that the alignment film formed of the alignment film composition provided by the present invention is excellent in moisture resistance and heat resistance.

1 is a side cross-sectional view of an optically anisotropic film according to the present invention,

2A and 2B are side cross-sectional views of a polarizing plate including the optically anisotropic film according to the present invention,

3 is a side cross-sectional view of a liquid crystal display device including the optically anisotropic film according to the present invention,

4 is a graph showing the phase difference of the optically anisotropic film prepared in Example 1,

5 is a graph showing the transmittance of the optically anisotropic film prepared in Example 2.

Claims (21)

0.1-10% by weight of polyvinyl alcohol (PVA), 0.01-2% by weight of crosslinking agent, 0.05-5% by weight of polyfunctional acrylic monomer, compatibility of the polyvinyl alcohol with the polyfunctional acrylic monomer based on the total weight of the alignment film composition An alignment film composition comprising 0.01 to 2% by weight of a poly (4-vinylphenol), 0.01 to 5% by weight of a photoinitiator, and a mixed solvent of the residual water and an alcohol to improve the viscosity. The alignment layer composition of claim 1, wherein the polyvinyl alcohol has a weight average molecular weight of 85,000 to 146,000. The alignment layer composition of claim 1, wherein the polyvinyl alcohol is hydrolyzed at 96% or less. The aldehydes and dialdehydes and 2-isocyanatoethyl 2-methylacrylic according to claim 1, wherein the crosslinking agent includes acrylaldehyde, oxalaldehyde, 2-methylacrylaldehyde, 2-oxopropanal and glutaraldehyde. Or at least one selected from the group consisting of isocyanates including latex, 1,4-diisocyanatobutane, 1,4-diisocyanatobenzene, and 1,3-diisocyanatobenzene is used. . The alignment film composition according to claim 1, wherein the multifunctional acrylic monomer is a polyfunctional acrylic monomer having 2 to 6 acrylic groups. The method of claim 1, wherein the multifunctional acrylic monomer is at least one selected from the group consisting of pentaerythritol triacrylate (PETA), pentaerythritol tetraacrylate (PETTA) and dipentaerythritol hexaacrylate (DPHA). The alignment film composition characterized by the above-mentioned. delete The alignment film composition of claim 1, wherein the photoinitiator is water-soluble. The method of claim 1, wherein the photoinitiator is Igacure 2959 (IRGACURE 2959, 2-hydroxy-1- [4- (2-hydroxyethoxy) phenyl] -2-methyl-1-propanone), Igacure 500 (IRGACURE 500, 1-hydroxy-cyclohexyl-phenyl-ketone and benzophenone) and Igacure 754 (IRGACURE 754, oxy-phenyl-acetic acid 2- [2 oxo-2 phenyl-acetoxy-ethoxy] -ethyl At least one member selected from the group consisting of esters and oxy-phenyl acetic 2- [2-hydroxy-ethoxy] -ethyl ester). The alignment layer composition of claim 1, wherein the water and the alcohol are mixed in a weight ratio of 40:60 to 50:50 in the mixed solvent of water and alcohol. The alignment layer composition according to claim 1, wherein the alcohol in the mixed solvent is at least one selected from the group consisting of methyl alcohol, ethyl alcohol and isopropyl alcohol. The alignment layer composition of claim 1, wherein the alignment layer composition is applied to a cyclo olefin-based polymer substrate. 0.1 to 10% by weight of polyvinyl alcohol (PVA), 0.05 to 5% by weight of polyfunctional acrylic monomer, 0.01 to 2% by weight of crosslinking agent, the polyvinyl alcohol and the multi-pipe on the cycloolefin polymer base based on the total weight of the alignment film composition Applying an alignment layer composition comprising 0.01 to 2% by weight of poly (4-vinylphenol), 0.01 to 5% by weight of photoinitiator, and a mixed solvent of water and alcohol to improve the compatibility of the functional acrylic monomer; Drying the applied alignment layer composition; Curing the dried alignment layer composition; And A method for producing a liquid crystal alignment film comprising the step of providing an orientation to the cured alignment film composition. The method for producing a liquid crystal alignment film according to claim 13, wherein the application of the alignment film composition is performed such that a dry coating thickness is 800 to 2000 kPa. The method of claim 13, wherein the drying is performed at 70 to 150 ° C. 15. The method for producing a liquid crystal alignment film according to claim 13, wherein the curing is performed by ultraviolet irradiation. Cyclo olefin-based polymer substrates; 0.1-10% by weight of polyvinyl alcohol (PVA), 0.01-2% by weight of crosslinking agent, 0.05-5% by weight of polyfunctional acrylic monomer, compatibility of the polyvinyl alcohol and the polyfunctional acrylic monomer on the cycloolefin polymer substrate An alignment film formed of an alignment film composition comprising 0.01 to 2% by weight of a poly (4-vinylphenol), 0.01 to 5% by weight of a photoinitiator, and a mixed solvent of the residual water and an alcohol to improve the orientation; And An optically anisotropic film comprising a liquid crystal layer formed on the alignment film. 18. The optically anisotropic film according to claim 17, wherein the liquid crystal layer is formed of a polymerizable liquid crystal compound having an acrylate group polymerizable by photoreaction. 19. The method of claim 18, wherein the polymerizable liquid crystal compound is a minimum selected from the group consisting of cyano biphenyl, cyano phenyl cyclohexane, cyano phenyl ester, benzoic acid phenyl ester, and phenyl pyrimidine-based acrylates. Optically anisotropic film, characterized in that more than one kind. A polarizing plate comprising the optically anisotropic film of claim 17. A liquid crystal display device comprising the polarizing plate of claim 20.

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