KR102028236B1 - Retardation film and liquid crystal display comprising the same - Google Patents

Abstract

The present specification relates to a retardation compensation film including a film containing a layered inorganic material having a phase difference expression (Rzy) of -12 nm to -25 nm at a film thickness of 1 μm at a wavelength of 550 nm, and a liquid crystal display including the same. will be. More specifically, the present invention relates to a retardation compensation film which can be applied as a retardation compensation film to an IPS mode liquid crystal display device and a liquid crystal display including the same.

Description

Retardation compensation film and liquid crystal display including the same {RETARDATION FILM AND LIQUID CRYSTAL DISPLAY COMPRISING THE SAME}

The present specification relates to a retardation compensation film and a liquid crystal display including the same. More particularly, the present invention relates to a retardation compensation film applicable to an IPS mode liquid crystal display and a liquid crystal display including the same.

BACKGROUND ART Liquid crystal displays have a widespread use as optical display elements because they have lower power consumption, smaller volume, lighter weight, and easier portability than cathode ray tube displays. In general, the liquid crystal display has a basic configuration in which polarizing plates are provided on both sides of the liquid crystal cell, and the orientation of the liquid crystal cell is changed depending on whether an electric field is applied to the driving circuit, thereby changing the characteristics of transmitted light emitted through the polarizing plate. Visualization takes place. At this time, the path and birefringence of the light change according to the incident angle of the incident light, because the liquid crystal is an anisotropic material having two different refractive indices.

Due to these characteristics, the liquid crystal display has a disadvantage in that the contrast ratio, which is a measure of how sharply the image is seen according to the viewing angle, changes, and gray scale inversion occurs, thereby reducing visibility. Has In order to overcome the disadvantages described above, an optical retardation compensation film (compensation film) for expressing the optical retardation occurring in the liquid crystal cell is used in the liquid crystal display device.

Meanwhile, various liquid crystal modes have been developed in order to secure clear image quality and wide viewing angle in liquid crystal displays. Representatively, Double Domain TN (Twisted Nematic), ASM (axially symmetric aligned microcell), and OCB (optically compensated blend) ), VA (vertical alignment), MVA (multidomain VA), SE (surrounding electrode), PVA (patterned VA), in-plane switching (IPS), fringe-field switching (FFS) mode, and the like. Each of these modes has a unique liquid crystal array and has inherent optical anisotropy.

Therefore, in order to express retardation due to optical anisotropy of these liquid crystal modes, an optical anisotropy retardation compensation film corresponding to each mode is required. In particular, in the IPS mode, since the liquid crystals having positive dielectric anisotropy are horizontally aligned, the optical anisotropy at the inclination angle in the non-driving state is not as large as that of other modes, so that an excellent wide viewing angle can be obtained only by using an isotropic protective film. . However, in this case, the compensation for the absorption axis of the polarizer is not made at high inclination angles, so contrast reduction and color modulation may still occur due to the viewing angle. Therefore, IPS mode liquid crystal display also requires a suitable phase difference compensation film to obtain a perfect wide viewing angle. Should be used.

The retardation compensation film for IPS mode requires a retardation compensation layer satisfying the condition of nx> nz> ny, but it is difficult to realize a general uniaxial or biaxially stretched film alone, and a structure composed of two or more multilayer films has been realistically proposed. In order to implement a multilayer film, a method of laminating each other film using an adhesive has been proposed. Alternatively, after preparing the stretched film through a separate stretching process, a process of coating a material expressing liquid crystal or phase difference is performed separately.

However, in the case of lamination using the pressure-sensitive adhesive as described above, it is difficult to reduce the thickness of the film, and if the optical axes of the two laminated films are not correctly disposed, there is a problem that manufacturing is very difficult, such as not showing a desired phase difference characteristic. In the case of separately performing a process of coating a liquid crystal after preparing the stretched film through the stretching process, the manufacturing process is complicated and has a disadvantage of increasing the manufacturing cost because it undergoes various steps such as a separate alignment process.

In addition, when the organic material is coated with a material that exhibits a phase difference, curl may occur or the phase difference of the base film may change due to substrate erosion by an organic solvent. In addition, a method of forming a -C plate on a + B plate has been attempted, but since the -C plate material is poor in durability and water resistance, it is necessary to add another additive to improve it. However, in the case of using the additives as described above, there is a disadvantage in that haze occurs in the film or dispersibility due to a decrease in compatibility between materials.

Korean public publication 2005-0101743

The present specification is to provide a liquid crystal display including a retardation compensation film and the retardation compensation film.

An exemplary embodiment of the present specification provides a phase difference compensation film including a film containing a layered inorganic material having a phase difference expression property (Rzy) represented by the following formula A for a film thickness of 1 μm at a wavelength of 550 nm of -12 nm to -25 nm. To provide.

Formula A: R _zy = (n _z -n _y )

In formula (1),

n _x is a refractive index in a direction in which the plane refractive index of the film containing the layered inorganic material becomes maximum,

n _y is a refractive index in the vertical direction in the n _x direction in the plane direction of the film containing the layered inorganic material,

n _z means the refractive index of the thickness direction of the film containing a layered inorganic substance.

According to another exemplary embodiment of the present specification, the retardation expression (Rzy) of the film thickness of 1 μm at a wavelength of 550 nm of the film containing the layered inorganic material is -15 nm to -25 nm.

The retardation compensation film according to another exemplary embodiment of the present specification further includes a base film provided on one surface of the film containing the layered inorganic material and including a negative birefringent material.

Retardation compensation film according to another embodiment of the present specification is provided on one side of the film containing the layered inorganic material, further comprises a base film containing a negative birefringent material, the film containing the layered inorganic material is It is a coating layer coated on the base film.

According to another exemplary embodiment of the present specification, the film containing the layered inorganic material includes a water-based urethane resin.

According to yet an embodiment of the present disclosure, the water dispersion urethane-based resin includes an aliphatic group.

According to yet an embodiment of the present disclosure, the weight ratio of the layered inorganic material and the water-dispersed urethane-based resin in the film containing the layered inorganic material is more than 1: 0.5 and 1: 2 or less.

According to yet an embodiment of the present disclosure, the layered inorganic material may include one or two or more selected from the group consisting of smectite. Specifically, the layered inorganic material may include one or two or more selected from the group consisting of hectorite, montmorillonite and bentonite.

According to yet an embodiment of the present disclosure, the average diameter of the layered inorganic material is 10 nm to 30 nm, the thickness is greater than 0 nm and 2 nm or less.

In one embodiment of the present specification, the layered inorganic material is in the form of a plate disk.

In another exemplary embodiment of the present specification, the layered inorganic material is represented by the following Structural Formula 1.

[Formula 1]

Na ⁺ _0.7 [(Si ₈ Mg _5.5 Li _0.3 ) O ₂₀ (OH) ₄ ] ^-0.7

In one embodiment of the present specification, the elongation of the water-dispersed urethane resin is 50% or more.

In another exemplary embodiment, the thickness direction retardation value R _th measured at a wavelength of 550 nm represented by the following Formula 1 of the film containing the layered inorganic material is -400 nm to 0 nm.

Formula (1): R _th = (n _z -n _y ) × d

In formula (1),

n _y is a refractive index in the vertical direction of the n _x direction in the surface direction of the coating layer,

n _x is the refractive index of the direction in which the surface refractive index of the coating layer is maximized,

n _z means the refractive index in the thickness direction,

d means the thickness of the coating layer.

In addition, in one embodiment of the present specification, the thickness of the coating layer is more than 0 20㎛ or less.

According to yet an embodiment of the present disclosure, the retardation compensation film satisfies the following formula (2) to formula (4).

Equation (2): 50 nm ≤ R _in ≤ 300 nm

Equation (3): 10 nm ≤ R _th ≤ 300 nm

Equation (4): 0.1 ≦ Nz <1

In the formulas (2) to (4),

R _in is a plane retardation value of the film measured at a wavelength of 550 nm,

R _th is the thickness retardation value of the film measured at a wavelength of 550 nm,

Nz is the ratio (R _th / R _in ) of the thickness direction retardation value to the surface direction retardation value measured at a wavelength of 550 nm.

According to yet an embodiment of the present disclosure, the retardation compensation film satisfies the following formula (5) and (6).

Equation (5)

1.02 <Rzy (450) / Rzy (550) <1.06

Formula (6)

0.98 <Rzy (650) / Rzy (550) <1.00

In formulas (5) and (6),

Rzy (450), R (550) and R (650) mean phase difference expression at wavelengths of 450 nm, 550 nm and 650 nm, respectively. Here, the phase difference expression can be calculated by the above-mentioned formula A.

In one aspect of the present specification, the base film is an acrylic resin; Styrene resins; And it is preferable that it contains 1 type, or 2 or more types chosen from the group which consists of a copolymer containing an acrylic monomer and a styrene monomer.

In another aspect of the present disclosure, the base film is a + B plate.

In another aspect of the present specification, the thickness of the base film is preferably 80 μm or less.

In one embodiment of the present specification, the base film and the coating layer are provided in contact.

Another embodiment of the present specification provides a polarizing plate including the aforementioned phase difference compensation film.

Another embodiment of the present specification provides an IPS mode liquid crystal display including the polarizing plate described above.

The retardation film according to an exemplary embodiment of the present specification has a retardation characteristic suitable for use as a retardation film for IPS mode, and thus has an excellent viewing angle improvement effect when applied as a retardation film for IPS mode. In addition, the retardation film according to one embodiment of the present specification does not require a separate alignment process, etc. Therefore, the manufacturing method is very simple as compared to the conventional method of coating the liquid crystal and the retardation expression material.

In addition, depending on the material or process, the thicker the coating thickness when forming the coating layer increases the amount of the solvent to be dried, in which case the moisture or solvent may remain in the coating layer without being completely dried. Thus, coating thickness and retardation expression can be inversely related. Therefore, according to the exemplary embodiment of the present specification, since a relatively large phase difference can be expressed even at a thin thickness, it is advantageous to implement a desired phase difference. In particular, _in the case of an IPS liquid crystal display device requiring a level of R _in 120 nm and R _th 60 nm, the phase difference expression (Rzy) for a film thickness of 1 μm at a wavelength of 550 nm according to the embodiment described herein is- By using a film of 12 nm to -25 nm together with the + B plate, it is advantageous to realize the phase difference required in the IPS liquid crystal display.

1 is a diagram illustrating an IPS mode liquid crystal display according to an exemplary embodiment of the present specification.

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

First, terms used in the present specification are defined.

In this specification, when a member is located "on" another member, this includes not only when a member is in contact with another member but also when another member exists between the two members.

In the present specification, when a part "contains" a certain component, this means that the component may further include other components, except for the case where there is no contrary description.

In the present specification, n _x is a refractive index in a direction (ie, a slow axis direction) in which a plane direction refractive index is maximum, and n _y is a refractive index in a direction (ie, a fast axis direction) in a direction perpendicular to the slow axis in the plane direction. , n _z means refractive index in the thickness direction.

In addition, n _x , n _y , n _z means a value measured in light of 550nm wavelength. On the other hand, the n _{x ,} n _y, n _z can be measured by a known method well known in the art, for example, by using a prism coupler device (SAIRON TECHNOLOGY Co. SPA-3DR) and the like to average refractive index By measuring the birefringence with an Axoscan of Axomatrics, n _{x ,} n _{y and} n _z can be calculated.

In the present specification, R _in means a plane direction retardation value measured at light of 550 nm wavelength, and the plane direction retardation value R _in (n _x -n _y ) × d to obtain. In this case, n _x and n _y are the same as described above, and d means the thickness of the optical film. On the other hand, the R _in can be measured by a known method well known in the art, for example, can be measured using Axoscan equipment of Axomatrics.

In the present specification, R _th means a thickness direction retardation value measured in light of 550 nm wavelength, and the thickness direction retardation value R _th = (n _z -n _y ) × d to obtain. In this case, n _y and n _z are the same as described above, and d means the thickness of the optical film. On the other hand, R _th can be measured by a known method well known in the art, for example, it can be measured using Axoscan equipment of Axomatrics.

In the present specification, Nz means the ratio of the thickness direction retardation value to the surface direction retardation value, and is obtained by Nz = R _th / R _in .

In the present specification, the negative birefringent material refers to a material that expresses an optical axis (refractive index in the direction in which the surface refractive index is maximum: n _x ) in a direction perpendicular to the stretching direction after stretching (after orientation), and may be coated only. In the case of (before stretching), it means a substance expressing a refractive index distribution of n _z > n _x = n _y . Definition A birefringent material refers to a material that expresses an optical axis in a direction parallel to the stretching direction after stretching (after orientation), and when coated only (before stretching), a refractive index distribution of n _x = n _y > n _z is expressed. It means a substance.

In the present specification, the thickness means an average width between one surface of a member and one surface opposite to the surface.

In the present specification, the + B plate means a film having a refractive index distribution of n _z ≥ n _x > n _y or n _x > n _z > n _y . N _x , n _y and n _z are the same as described above.

In the present specification, a -C plate means a film having a refractive index distribution of n _x = n _y > n _z . N _x , n _y and n _z are the same as described above.

Hereinafter, preferred embodiments of the present specification will be described. However, the embodiments herein may be modified in many different forms and should not be construed as limited to the embodiments set forth herein. In addition, the embodiments of the present specification are provided to more fully describe the present specification to those skilled in the art.

<Film containing layered inorganic material>

In the present specification, the film containing the layered inorganic material has a phase difference expression (Rzy) represented by the above formula A with respect to the film thickness of 1 μm at a wavelength of 550 nm (Rzy) of -12 nm to -25 nm and containing a layered inorganic material. It features. As such, when a coating layer including a layered inorganic material is included on at least one surface of the base film, curl generation may be minimized and a desired phase difference may be realized even with a thickness of a thin layer.

According to another exemplary embodiment of the present specification, the retardation expression (Rzy) of the film thickness of 1 μm at a wavelength of 550 nm of the film containing the layered inorganic material is -15 nm to -25 nm.

The retardation compensation film according to another exemplary embodiment of the present specification may further include a base film provided on one surface of the film containing the layered inorganic material. This?, The base film may be a base film containing a negative birefringent material.

For example, the retardation compensation film is provided on one surface of the film containing the layered inorganic material, and further comprises a base film containing a negative birefringent material, the film containing the layered inorganic material is a coating layer coated on the base film to be.

According to an exemplary embodiment, the film containing the layered inorganic material includes a water-dispersed urethane-based resin and at least one layered inorganic material dispersed in the resin. The film containing the layered inorganic material may be formed by a coating composition including the layered inorganic material, a resin, and a solvent.

As described above, when the coating layer is formed using the coating composition including the layered inorganic material, curl generation may be minimized and a desired retardation compensation film may be realized even with a thin layer thickness.

In the present specification, the layered inorganic material may include one or two or more selected from the group consisting of smectite systems.

According to an exemplary embodiment of the present specification, the layered inorganic material may be one or two or more selected from the group consisting of hectorite, montmorillonite, and bentonite. However, the present invention is not limited thereto, and may be selected from the group consisting of composites having similar crystal structures.

In addition, in an exemplary embodiment of the present specification, the average diameter of the layered inorganic material is 10 nm to 30 nm, and the thickness is more than 0 nm and 2 nm or less. In one embodiment, the average diameter of the layered inorganic material is 15 nm to 25 nm.

In another embodiment, the thickness is 0.5 nm to 1 nm.

In the present specification, the layered inorganic material may be in the form of a plate disk. The average diameter may mean an average diameter of the cross section of the plate, the thickness may mean a distance between the lower surface and the upper surface of the layered inorganic material. The average diameter and thickness may be measured by methods used in the art.

In one embodiment of the present specification, the layered inorganic material is represented by the following structural formula (1).

[Formula 1]

Na ⁺ _0.7 [(Si ₈ Mg _5.5 Li _0.3 ) O ₂₀ (OH) ₄ ] ^-0.7

In the exemplary embodiment of the present specification, the layered inorganic material is represented by Structural Formula 1 in terms of retardation expression, transparency, dispersibility with a water dispersion binder, swelling between layers, cation exchange ability, and / or surface modification. More preferred.

In one embodiment of the present specification, the layered inorganic material used in preparing the coating composition for forming a film containing the layered inorganic material may be provided in a form dispersed in water. That is, the layered inorganic material according to the exemplary embodiment of the present specification may be selected from one type or two types or more among the layered inorganic materials that can be dispersed.

In this case, erosion of other members can be prevented compared with the case of including the layered inorganic substance dispersed in the organic solvent, and deformation of the expression of the phase difference value can be prevented.

In the present specification, the "water dispersion urethane-based resin" means a urethane-based resin which may exist in a dispersed state in water.

As described above, in the case of using a water-dispersed urethane-based resin, it is possible to prevent environmental pollution due to the release of harmful solvents, there is an excellent effect of stability of the particles in the water dispersion phase. In addition, when using a water-dispersible resin, the problem that a substrate erosion appears by an organic solvent and the phase difference of a base film changes can be prevented.

According to one embodiment, the water-dispersed urethane-based resin includes an aliphatic unit. In this case, it is possible to form a coating layer having excellent toughness. More preferably, in one embodiment of the present specification, the water-dispersed urethane-based resin includes only aliphatic units. That is, it does not contain an aromatic unit.

As used herein, the term "aliphatic unit" may refer to a structure that does not include an aromatic structure such as benzene as a structural unit. If it does not include the aromatic structure, it is not limited to a straight chain, branched chain, cyclic, and may be composed of only hydrocarbons, but may contain a hetero atom so long as the effect of the invention is not impaired.

For example, Saturated aliphatic units, such as a methyl group, an ethyl group, a propyl group, isopropyl group, a butyl group, t-butyl group, a pentyl group, a hexyl group, a heptyl group, a cyclopentyl group, and a cyclohexyl group; Unsaturated aliphatic units such as vinyl, 1-propenyl, isopropenyl, cyclohexenyl, and the like, and the like, and may include a structure substituted with a heteroatom such as S, O, or N instead of a carbon atom. have.

In the present specification, the urethane-based resin may have a structure having a urethane bond in a molecule, and may be prepared by a method known in the art, for example, may be prepared by reaction of diisocyanate (-NCO) with a polyol, but is not limited thereto. .

The urethane-based resin in the present specification is sufficient to include a urethane monomer of "-O- (C = O) -NH-R-HN- (C = O) -O-", and may further include an additional monomer. . R may be a divalent aliphatic unit.

In one embodiment of the present specification, in terms of toughness, R is preferably an alicyclic structure or a linear saturated aliphatic unit.

Specifically, according to an exemplary embodiment of the present specification, the water-dispersed urethane-based resin may be a resin containing only the above-described urethane monomer.

The water-dispersed urethane-based resin according to another embodiment may be a copolymer comprising the aforementioned urethane monomer and additional monomers.

The additional monomer is not limited as long as it is a monomer known in the art, but may include a monomer including a carbonate group (“-O— (C═O) —O—”); Monomers comprising an ester group (ester "-(C = O) -O-"); And it may be one or two or more selected from the group consisting of monomers containing an ether group (ether ("-O-")).

In one embodiment of the present specification, the water-dispersed urethane-based resin may be a resin including a copolymer including a urethane monomer and a carbonate monomer.

In one embodiment of the present specification, the water-dispersed urethane resin includes a urethane monomer including an aliphatic unit; Or a copolymer of one or two or more monomers selected from the group consisting of a urethane monomer comprising an aliphatic unit and a monomer comprising a carbonate group, a monomer comprising an ester group and a monomer comprising an ether group.

In one embodiment of the present specification, the elongation of the water-dispersed urethane resin is 50% or more. In this case, the coating layer can be prevented from breaking down, thereby improving durability. In addition, excellent effects can be expected in terms of toughness and adhesion to other members.

According to an exemplary embodiment of the present specification, the film containing the layered inorganic material has excellent adhesion to the base film. For example, on one side of the film containing the layered inorganic material, 11 lines were drawn horizontally and vertically with an office knife to form 100 square shapes, and then a tape of NICHIBAN Corporation of Japan was put on it and pulled out quickly by hand. In the adhesion evaluation by counting how many squares remain, good adhesion can be exhibited with more than 90 squares remaining.

In the present specification, the elongation means a rate at which the material is stretched during the material tension test, and a method of measuring elongation may use a method known in the art.

In another exemplary embodiment, the film containing the layered inorganic material may be progressed by a method known in the art. For example, the layered inorganic material may be dispersed in water and then mixed with a water-dispersed urethane-based binder resin to form a coating composition. Can be prepared, applied and dried. The coating method is not particularly limited, and methods known in the art may be used, for example, bar coating, slot die coating, spray coating, flow coating, roll coating, dip coating, micro gravure coater, A comma coater etc. can be used.

In addition, the method of forming a film containing the layered inorganic material in the present specification may use a method known in the art, for example, by using a method of directly forming a coating layer on the base film, or separately produced the film Although there is a method of forming by using an adhesive or an adhesive, a direct coating method is economical in terms of time and cost of the process, and is preferable in view of retardation.

The content of the layered inorganic and water-dispersed urethane-based resin is 4% by weight to 15% by weight, and the content of the solvent is 85% by weight to 96% by weight.

In one embodiment, the solids content of the total weight of the coating solution composition is 4% by weight to 15% by weight, the content of the solvent is from 85% by weight to 96% by weight.

In the present specification, when the content of solids in the coating solution composition exceeds 15% by weight, the dispersion of the inorganic material is not well achieved, the viscosity is too high uniform coating is difficult to cause unevenness and / or poor appearance of the phase difference have. In addition, when the content of the solid content is less than 4% by weight, the viscosity is low, a problem may occur during coating, the drying efficiency is low, the area of the coating layer that can be obtained compared to the amount of the coating solution is uneconomical.

Therefore, as in the exemplary embodiment of the present specification, the case where the content of the layered inorganic material and the water-dispersed urethane resin is in the above range is preferable in view of the process and retardation characteristics.

In the present specification, the solid content means a solute or solid except for the solvent in the total mass of the solution. Solid content in the coating liquid composition of the present specification may mean a layered inorganic material and a water-dispersed urethane-based resin.

In one embodiment, the solvent comprises water.

In another embodiment, the solvent is an alcohol, such as ethanol, methanol; And one or two or more solvents selected from the group consisting of ketones such as acetone, methyl ethyl ketone (MEK) may be further included.

In one embodiment of the present specification, the content of the water relative to the total weight of the coating composition may be 85% by weight to 96% by weight.

In one embodiment of the present specification, the water content is 50% by weight to 100% by weight based on the total weight of the solvent, and the content of one or two or more solvents selected from the group consisting of alcohols and ketones is 0. Weight percent to 50 weight percent.

In one embodiment of the present specification, the content of one or two or more solvents selected from the group consisting of alcohols and ketones preferably includes 0 wt% to 20 wt% with respect to the total amount of water.

As in the exemplary embodiment of the present specification, when the water content is 50% by weight or more of the total content of the solvent, it is possible to prevent erosion of the substrate by using an organic solvent and to prevent deformation of the phase difference due to erosion of the substrate. . In addition, by minimizing the generation of the curl of the coating layer formed using the coating composition, it is possible to effectively implement to prevent the defects occurring during the increase of the viewing angle compensation effect, the durability and the lamination process with other members. In view of the above, the content of water in the total solvent is preferably 70% by weight or more, and more preferably 80% by weight or more.

In another exemplary embodiment, the water content is 75 wt% to 96 wt% with respect to the total weight of the coating composition, and the content of one or two or more solvents selected from the group consisting of alcohols and ketones is 0. Weight percent to 10 weight percent.

According to an exemplary embodiment of the present specification, the coating liquid composition may include the layered inorganic material and the water-dispersed urethane-based binder resin in a weight ratio of 1: 0.5 to 1: 2. In other words, the weight ratio of the layered inorganic material and the water-dispersed urethane-based resin in the film containing the layered inorganic material may be 1: 0.5 to 1: 2.

According to yet an embodiment of the present disclosure, the weight ratio of the layered inorganic material and the water-dispersed urethane-based resin in the film containing the layered inorganic material is greater than 1: 0.5 to 1: 1.

According to yet an embodiment of the present disclosure, the weight ratio of the layered inorganic material and the water-dispersed urethane resin in the film containing the layered inorganic material is 1: 0.6 or more and 1: 0.8 or less.

When the weight ratio of the layered inorganic material and the water-dispersed urethane-based binder resin is within the above range, it is advantageous to prevent cracking of the layer, thereby improving the mechanical properties of the retardation film for IPS mode liquid crystal display device.

In one embodiment of the present specification, the film containing the layered inorganic material is a -C plate. In this case, the film containing the layered inorganic material may be introduced into the base film of the + B plate to express optical properties required in the retardation compensation film for the IPS mode liquid crystal display device, and may provide high viewing angle compensation performance.

In one embodiment, the thickness direction retardation value (R _th ) of the film measured at a wavelength of 550 nm represented by the following formula 1 of the film containing the layered inorganic material is -400 nm to 0 nm. In the case of a film containing a layered inorganic substance having the above thickness direction retardation value, it can be very usefully used as a retardation compensation film for an IPS mode liquid crystal display device together with a base film described later. In one embodiment of the present specification, the thickness direction retardation value R _th of the film measured at a wavelength of 550 nm of the film containing the layered inorganic material is more preferably -120 nm to -100 nm.

Formula (1): R _th = (n _z -n _y ) × d

In formula (1),

n _y is a refractive index in the vertical direction of the n _x direction in the surface direction of the coating layer,

n _x is the refractive index of the direction in which the surface refractive index of the coating layer is maximized,

n _z means the refractive index in the thickness direction,

d means the thickness of the coating layer.

According to another exemplary embodiment, the thickness of the film containing the layered inorganic material is greater than 0 and 20 µm or less. More preferably, it may be more than 0 and 15 micrometers or less. When the thickness of the film containing the layered inorganic material satisfies the above range, there is an advantage that it can meet the trend of thinning of the display field while minimizing problems such as poor drying, film curl, and the like.

<Substrate film>

In the present specification, "including birefringent material of moiety" may be interpreted as "having retardation property of moiety". In other words, the base film including a negative birefringent material may be a base film having negative phase difference characteristics.

In one embodiment of the present specification, the base film is an acrylic resin; Styrene resins; And it may include one or two or more selected from the group consisting of a copolymer comprising an acrylic monomer and a styrene monomer.

Specifically in one embodiment of the present specification, the base film is an acrylic resin; Blended resins of acrylic resins and styrene resins; Or a copolymer comprising an acrylic monomer and a styrene monomer.

In the present specification, the "blend resin" may mean mixing two or more resins, and the "copolymer" may mean one polymer formed by polymerizing two or more monomers.

In the present specification, the acrylic resin includes an acrylate monomer and / or a methacrylate monomer as main components, and an acrylate monomer and / or a homopolymer resin composed of an acrylate monomer or a methacrylate monomer. Or a copolymer resin copolymerized with other monomers in addition to the methacrylate monomer.

In this case, the methacrylate monomer is a concept including not only methacrylate but also methacrylate derivatives, such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n -butyl methacrylate, t -butyl Methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, methoxyethyl methacrylate, ethoxyethyl methacrylate, butoxymethyl methacrylate or oligomers thereof, and the like. Among them, methyl methacrylate is more preferable, but is not necessarily limited thereto. These may be used alone or in combination.

In addition, the acrylate monomer is a concept including not only acrylates but also acrylate derivatives, such as methyl acrylate, ethyl acrylate, propyl acrylate, n -butyl acrylate, t -butyl acrylate and cyclohexyl acrylate. , Phenyl acrylate, benzyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, butoxy methyl acrylate or oligomers thereof, and the like, but more preferably methyl acrylate, but is not limited thereto. It is not. These may be used alone or in combination.

In addition, the styrene resin in the present specification includes a styrene monomer, styrene, α-methyl styrene, 4-methyl styrene and the like, but is not limited thereto.

The styrene monomer is preferably prepared in the form of copolymerization with an acrylic monomer, but alternatively, another styrene copolymer may be included by blending with a polymer composed of the acrylic monomer. For example, the copolymer including the acrylic monomer and the styrene monomer may include styrene-maleic anhydride copolymer (SMA), styrene-acrylonitrile copolymer (SAN), and α-methylstyrene-acrylonitrile copolymer (AMSAN ), Etc., but is not limited thereto.

On the other hand, in order to improve heat resistance, the acrylic resin may include a lactone monomer, a maleic anhydride monomer, a maleimide monomer, and the like as other monomers than the (meth) acrylic monomer. In this case, the maleic anhydride monomers include maleic anhydride, methyl maleic anhydride, ethyl maleic anhydride, propyl maleic anhydride, isopropyl maleic anhydride, cyclohexyl maleic anhydride, and phenyl maleic anhydride. Can be; Examples of the maleimide monomers include maleimide, N-methyl maleimide, N-ethyl maleimide, N-propyl maleimide, N-isopropyl maleimide, N-cyclohexyl maleimide, N-phenyl maleimide, and the like. For example, but is not limited thereto. These may be used alone or in combination.

In another exemplary embodiment, when the blend film of the acrylic resin and the styrene resin is used, the base film may expect high heat resistance of the acrylic resin and high retardation expression of the styrene resin.

It is preferable that the glass transition temperature (Tg) of the said base film is 100 degreeC-160 degreeC. When the glass transition temperature (Tg) is within the above range, it may have excellent durability. On the other hand, when the glass transition temperature is less than 100 ° C., heat resistance may be insufficient, which may cause deformation of the film under high temperature and high humidity conditions. There is a problem of this unevenness.

In one embodiment of the present specification, the base film has a plane direction retardation value R _in of the film measured at a wavelength of 550 nm of 95 nm to 120 nm.

In another exemplary embodiment, the base film has a thickness retardation value R _th of the film measured at a wavelength of 550 nm of 150 nm to 160 nm.

The plane retardation value and the thickness retardation value may be calculated by the aforementioned method.

The base film may be a film uniaxially stretched in the width direction or a film biaxially stretched in the longitudinal direction (MD) and in the width direction (TD).

The uniaxial or biaxial stretching may be performed by a method known in the art, for example, the stretching may be manufactured in a tender provided with a preheating unit, a stretching unit and a heat treatment unit. Preheating refers to a process of softening the base film by heating in advance so that it can be stretched well in the stretching step, which is the next step, wherein the base film introduced into the preheater is heated at a temperature lower than Tg, and then the Tg of the film at the stretching portion. The stretching treatment is performed at a higher temperature. Thereafter, the stretched base film is subjected to heat treatment for the purpose of fixing the orientation of the film in the heat treatment portion. In this case, the stretching ratio may be adjusted in the stretching unit according to the phase difference value to be obtained.

According to an exemplary embodiment of the present specification, the base film is a + B plate.

According to an exemplary embodiment of the present specification, the thickness of the base film is 80㎛ or less. Specifically, the thickness may be 70 μm or less or 60 μm or less. More specifically, the thickness may be greater than 0 μm and 50 μm or less. In one embodiment of the present specification, the thickness of the base film may be 30㎛ to 40㎛.

< Phase difference  Compensation Film>

The retardation compensation film according to the exemplary embodiment of the present specification may include a film containing a layered inorganic material, and may further include a base film including a negative birefringent material as necessary.

According to an exemplary embodiment, the retardation compensation film satisfies Equations (2) to (4). In this case, it can be very usefully used as a retardation compensation film for an IPS mode liquid crystal display device.

In one embodiment of the present specification, the phase difference compensation film is for an IPS mode liquid crystal display device.

In addition, in the present specification, the value of R _in of the retardation compensation film is more preferably 90 nm to 250 nm, and more preferably, the value of R _th of the retardation compensation film is 30 nm to 100 nm.

Moreover, it is preferable that Nz value of retardation compensation film is 0.2-0.9.

The retardation compensation film according to an exemplary embodiment of the present specification may satisfy a relationship of n _{x, total} > n _{z, total} > n _{y, total} .

n _{x, total} is the refractive index of the direction (ie, the slow axis direction) in which the planar refractive index of the entire retardation compensation film is maximized,

n _{y, total} is a refractive index in a direction perpendicular to the slow axis of the entire retardation compensation film (ie, a fast axis direction),

n _{z, total} is the refractive index of the thickness direction of the whole retardation compensation film.

According to yet an embodiment of the present disclosure, the retardation compensation film satisfies the following formula (5) and (6).

Equation (5)

1.02 <Rzy (450) / Rzy (550) <1.06

Formula (6)

0.98 <Rzy (650) / Rzy (550) <1.00

In formulas (5) and (6),

Rzy (450), R (550) and R (650) mean phase difference expression at wavelengths of 450 nm, 550 nm and 650 nm, respectively. Here, the phase difference expression can be calculated by the above-mentioned formula A. As described above, when the equations (5) and (6) are satisfied, the reverse wavelength dispersion characteristic in which the phase difference decreases as the wavelength decreases can be realized. It is advantageous to realize.

In one embodiment of the present specification, the base film and the film containing the layered inorganic material are provided in contact with each other. That is, in one embodiment of the present specification, the base film and the film containing the layered inorganic material provide an integrated composite retardation compensation film.

That is, the retardation compensation film according to an exemplary embodiment of the present specification may not include an additional member such as a primer layer, an adhesive layer, and an adhesive layer between the base film and the film containing the layered inorganic material.

In this case, due to the additional member, the influence by the stress from the outside can be minimized, and the optical properties can be prevented from deteriorating. In addition, the film can be thinned and is easy in terms of manufacturing process and cost.

In another exemplary embodiment, an additional member may be further included between the base film and the film containing the layered inorganic material.

In one embodiment of the present specification, the overall thickness of the retardation compensation film including the base film and the film containing the layered inorganic material may be 20 μm to 100 μm, but is not limited thereto. If the thickness is less than 20 μm, the retardation compensation film does not properly support the polarizer, and thus polarizer shrinkage, polarizer cracks, curls, etc. are likely to occur. There is a problem that a defect occurs due to poor drying of the pressure-sensitive adhesive.

On the other hand, in the manufacturing of the retardation compensation film according to one embodiment of the present specification, if necessary, may further include an additive known in the art. Non-limiting examples of additives include dispersants, surface additives, lubricants, thermal stabilizers, UV absorbers, plasticizers, antioxidants, etc., from 0 to 10 parts by weight per 100 parts by weight of the phase difference compensation film for all IPS mode liquid crystal display devices It may be included in parts by weight. The additive may be included in the base film, the coating layer or the hard coating layer.

An exemplary embodiment of the present specification also provides a method of manufacturing the aforementioned retardation compensation film. Specifically, preparing a base film having a negative retardation characteristics; And forming a coating layer including a layered inorganic material and an aqueous urethane-based resin on at least one surface of the base film.

Description of the layered inorganic material and the water-dispersed urethane-based resin contained in the base film, the coating layer is as described above.

An exemplary embodiment of the present specification also provides a polarizing plate including the aforementioned retardation compensation film. In this case, the polarizing plate may have a component known in the art, a lamination order, and the like, except that the polarizing plate includes a phase difference compensation film according to an exemplary embodiment of the present specification. For example, the protective film may further include.

Specifically, the polarizing plate is a polyvinyl alcohol polarizer; And a retardation compensation film according to the above-described exemplary embodiment provided on at least one surface of the polarizer. The polarizing plate may further include a protective film provided on at least one surface of the polarizer. For example, the protective film may be provided between the polarizer and the retardation protective film, and / or on the opposite side of the surface provided with the retardation protective film of the polarizer.

An exemplary embodiment of the present specification also provides an IPS mode liquid crystal display device including a retardation compensation film or a polarizing plate according to the aforementioned exemplary embodiments.

In this case, the IPS mode liquid crystal display device may include a liquid crystal cell and a first polarizing plate and a second polarizing plate respectively provided on both sides of the liquid crystal cell, and the phase difference compensation film for the IPS mode liquid crystal display device may include the liquid crystal cell. It may be provided between the first polarizing plate and / or the second polarizing plate. That is, the retardation compensation film may be provided between the first polarizing plate and the liquid crystal cell, or may be provided between the second polarizing plate and the liquid crystal cell, or between the first polarizing plate and the liquid crystal cell and between the second polarizing plate and the liquid crystal cell. One or two or more to all It may be provided.

In addition, the first polarizing plate and the second polarizing plate may further include a protective film on one or both surfaces of the polarizer and the polarizer, respectively. The protective film may be used if known in the art, for example, a polynorbornene-based film made of a triacetate cellulose (TAC) film, an acrylic film ring opening metathesis polymerization (ROMP) as an inner protective film. The ring opening metathesis polymerization followed by hydrogenation (HROMP) polymer film, a polyester film, or a polynorbornene-based film prepared by addition polymerization may be used. In addition, a film made of a transparent polymer material may be used as a protective film, but is not limited thereto.

In addition, the protective film may further include a surface coating layer. The surface treatment layer may include a high hardness layer, an anti-glare layer such as an AG (anti-glare) layer or a semi-glare (SG) layer, or a low reflection layer such as an anti reflection (AR) layer or a low reflection (LR) layer. May be exemplified.

1 illustrates a laminated structure of a liquid crystal display including the polarizing plate and the IPS panel described above. In the liquid crystal display of FIG. 1, a polarizer 601 is provided on one side of the IPS panel 101, and a phase difference including a base film 401 and a coating layer 301 between the polarizer 601 and the IPS panel 101. Compensation film is provided. A protective film 701 may be provided on an opposite surface of the polarizer 601 facing the IPS panel, and a surface coating layer 801 may be provided on a surface of the protective film 701. The adhesive layer 201 may be provided on the coating layer 301 and the IPS panel 101. In addition, a primer layer 501 may be provided at one side of the polarizer 601. 1 is not intended to limit the scope of the present disclosure, and the structure of FIG. 1 may be variously modified within the scope of the present disclosure. For example, the other side of the IPS panel is provided with a polarizing plate, the polarizing plate may be the same as the structure provided in Figure 1, the structure provided in Figure 1 may be a modified structure, the polarizing plate known in the art May be used.

Hereinafter, the present specification will be described in more detail with reference to Examples. However, the following examples are provided to illustrate the present specification, and the scope of the present specification is not limited thereto.

< Example  1> to < Example  6>

A coating solution composition prepared by mixing 4.5 wt% of laponite (BYK) and 3.15 wt% (trade name: Superflex 460S (DKS), a water-dispersed urethane resin) (laponite: 460S weight ratio 1: 0.7) in water After coating the coating layer of the -C plate using a bar coater on a base film trade name FN-A film (Japan Catalyst Co., Ltd.) which is a plate, it was dried at 100 ° C. for 5 minutes to prepare a retardation film. Thickness and retardation expression of the coating layer is shown in Table 1 below.

Coating layer thickness (μm) Rzy, phase contrast expression (μm / nm) Example 1 1.2 -24.3 Example 2 2.5 -21.1 Example 3 4.5 -18.5 Example 4 5.2 -19.6 Example 5 5.7 -18.6 Example 6 7.1 -18.6

< Example  7> to < Example  9>

Same as in Example 1 except that 4.0 wt% of laponite (BYK Co.) and 2.4 wt% (trade name Superflex 460S (DKS Co.) of the water-dispersed urethane resin) were used (laponite: 460S weight ratio 1: 0.6). Was carried out. Thickness and retardation expression of the coating layer is shown in Table 2 below.

Coating layer thickness (μm) Rzy, phase contrast expression (μm / nm) Example 7 1.4 -23.7 Example 8 2.4 -19.3 Example 9 3.3 -18.2

< Example  10> to < Example  12>

As in Example 1, except that 3.5 wt% of laponite (BYK) and 2.8 wt% (trade name Superflex 460S (DKS)) of the water-dispersed urethane resin (Laponite: 460S weight ratio 1: 0.8) were used. Was carried out. Thickness and retardation expression of the coating layer is shown in Table 3 below.

Coating layer thickness (μm) Rzy, phase contrast expression (μm / nm) Example 10 4.4 -13.4 Example 11 7.4 -14.1 Example 12 9.2 -12.7

< Example  13> to < Example  16>

As in Example 1, except that 3.5 wt% of laponite (BYK) and 2.1 wt% of the superdispersed urethane resin (trade name Superflex 460S (DKS)) were used (laponite: 460S weight ratio 1: 0.6). Was carried out. Thickness and retardation expression of the coating layer is shown in Table 4 below.

Coating layer thickness (μm) Rzy, phase contrast expression (μm / nm) Example 13 2.6 -16.2 Example 14 3.9 -17.4 Example 15 4.7 -17.2 Example 16 5.6 -17.7

< Example  17> to < Example  19>

As in Example 1, except that 4.0 wt% of laponite (BYK) and 4.8 wt% of the water-dispersed urethane resin, NeoRez R600 (DSM), were used (laponite: 460S weight ratio 1: 1.2). Was carried out. Thickness and retardation expression of the coating layer is shown in Table 5 below.

Coating layer thickness (μm) Rzy, phase contrast expression (μm / nm) Example 17 4.4 -11.5 Example 18 8.9 -9.2 Example 19 11.5 -9.3

< Comparative example  1> to < Comparative example  3>

The same procedure as in Example 1 was carried out except that the binder shown in Table 6 was used instead of the water-based urethane resin. The mixing ratio of the laponite and the binder resin, the thickness of the coating layer and the retardation expression properties are shown in Table 6 below.

Binder resin Mixing ratio of laponite and binder resin Coating layer
thickness
(μm) Rzy, phase contrast expression (μm / nm) Comparative Example 1 Hybridur 560
(Air products) 3.0wt%: 3.0wt% 4.6 -3.7 Comparative Example 2 Hybridur 570
(Air products) 3.0wt%: 3.0wt% 7.3 -2.1 Comparative Example 3 Hybridur 580
(Air products) 3.0wt%: 3.0wt% 2.6 -3.4 Comparative Example 4 Hybridur 870
(Air products) 3.0wt%: 3.0wt% 4.2 -10.3 Comparative Example 5 Hybridur 878
(Air products) 3.0wt%: 3.0wt% 1.5 -6.5 Comparative Example 6 PVP K-30
(ASHLAND company) 3.0wt%: 3.0wt% 10.1 -0.0 Comparative Example 7 PVP K-60
(ASHLAND company) 3.0wt%: 3.0wt% 13.2 -0.3 Comparative Example 8 PVA 217
Kuraray 3.0wt%: 3.0wt% 8.7 -1.4 Comparative Example 9 Hydran RCP A220
(DIC) 2.5wt%: 2.5wt% 3.0 -9.9 Comparative Example 10 Hydran RCP A220
(DIC) 3.0wt%: 3.0wt% 5.0 -11.4

801 surface coating layer
701: protective film
601: polarizer
501: primer layer
401: base film
301: coating layer
201: adhesive layer
101: IPS panel

Claims (18)

Retardation expression (Rzy) represented by the following formula A for a film thickness of 1 μm at a wavelength of 550 nm includes a film containing -12 nm to -25 nm and containing a layered inorganic material,
Retardation compensation film which satisfy | fills following formula (5) and formula (6):
Formula A: R _zy = (n _z -n _y )
In formula A,
n _x is a refractive index in a direction in which the plane refractive index of the film containing the layered inorganic material becomes maximum,
n _y is a refractive index in the vertical direction in the n _x direction in the plane direction of the film containing the layered inorganic material,
n _z means the refractive index of the thickness direction of the film containing the layered inorganic material,
Equation (5)
1.02 <Rzy (450) / Rzy (550) <1.06
Formula (6)
0.98 <Rzy (650) / Rzy (550) <1.00
In formulas (5) and (6),
Rzy (450), R (550) and R (650) mean phase difference expression at wavelengths of 450 nm, 550 nm and 650 nm, respectively. The retardation compensation film according to claim 1, wherein retardation expression (Rzy) with respect to a film thickness of 1 μm at a wavelength of 550 nm of the film containing the layered inorganic material is -15 nm to -25 nm. The retardation compensation film of claim 2, wherein the retardation compensation film further includes a base film provided on one surface of the film containing the layered inorganic material and including a negative birefringent material. The method according to claim 1, wherein the retardation compensation film is provided on one side of the film containing the layered inorganic material, further comprises a base film containing a negative birefringent material, the film containing the layered inorganic material is on the base film Retardation compensation film that is a coated coating layer. The phase difference compensation film of claim 1, wherein the film containing the layered inorganic material includes a water-dispersed urethane-based resin. The phase difference compensation film of claim 5, wherein the water-dispersed urethane resin includes an aliphatic group. The retardation compensation film according to claim 5, wherein a weight ratio of the layered inorganic material and the water-dispersed urethane resin in the film containing the layered inorganic material is greater than 1: 0.5 and 1: 2 or less. The retardation film according to claim 5, wherein a weight ratio of the layered inorganic material and the water-dispersed urethane-based resin in the film containing the layered inorganic material is greater than 1: 0.5 and less than 1: 1. The phase difference compensation film of claim 1, wherein the layered inorganic material includes one or two or more selected from the group consisting of smectite systems. The phase difference compensation film of claim 1, wherein the layered inorganic material includes one or two or more selected from the group consisting of hectorite, montmorillonite, and bentonite. The phase difference compensation film of claim 5, wherein the elongation of the water-dispersed urethane resin is 50% or more. The phase difference compensation film of claim 1, wherein the film containing the layered inorganic material is a -C plate. The retardation compensation film of claim 3, wherein the base film is a + B plate. The retardation compensation film of claim 1, wherein the retardation compensation film satisfies the following formulas (2) to (4):
Equation (2): 50 nm ≤ R _in ≤ 300 nm
Equation (3): 10 nm ≤ R _th ≤ 300 nm
Equation (4): 0.1 ≦ Nz <1
In the formulas (2) to (4),
R _in is a plane retardation value of the film measured at a wavelength of 550 nm,
R _th is the thickness retardation value of the film measured at a wavelength of 550 nm,
Nz is the ratio (R _th / R _in ) of the thickness direction retardation value to the surface direction retardation value measured at a wavelength of 550 nm. delete The retardation compensation film according to claim 3, wherein the base film and the film containing the layered inorganic material are provided in contact with each other. A polarizing plate comprising the phase difference compensation film according to any one of claims 1 to 14 and 16. An IPS mode liquid crystal display comprising the polarizing plate according to claim 17.

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