KR20170001163A - Retardation film and liquid crystal display comprising the same - Google Patents

Abstract

The present invention relates to: a coating liquid composition including a layered inorganic material, an aqueous dispersion urethane-based resin, and a solvent, wherein the aqueous dispersion urethane-based resin has an aliphatic unit; to a coating layer formed by using the coating liquid composition; to a retardation film including the coating layer; and to a liquid crystal display device comprising the retardation film. The retardation film can be applied to an IPS mode liquid crystal display device.

Description

TECHNICAL FIELD [0001] The present invention relates to a retardation film and a liquid crystal display device including the retardation film.

The present invention relates to a coating liquid composition, a coating layer formed using the coating liquid composition, a retardation film including the coating layer, and a liquid crystal display including the same. More particularly, the present invention relates to a retardation film that can be applied to an IPS mode liquid crystal display device as a retardation film, and a liquid crystal display device including the retardation film.

The liquid crystal display is spreading as an optical display device because it has lower power consumption, smaller volume, lighter weight and easier to carry than a cathode ray tube display. In general, a liquid crystal display has a basic structure in which a polarizing plate is provided on both sides of a liquid crystal cell, and the orientation of the liquid crystal cell is changed according to whether an electric field of the driving circuit is applied or not and the characteristics of light transmitted through the polarizing plate are changed, Visualization is done. At this time, the path of light and the birefringence change depending on the incident angle of the incident light because the liquid crystal is an anisotropic material having two different refractive indices.

Due to such characteristics, the liquid crystal display has a disadvantage that the contrast ratio, which is a measure of how clearly the image looks depending on the viewing angle, is changed and a gray scale inversion phenomenon occurs, . In order to overcome such disadvantages, an optical compensation film for developing an optical retardation generated in a liquid crystal cell is used for a liquid crystal display device.

Various liquid crystal modes have been developed to secure a clear image quality and a wide viewing angle in a liquid crystal display. Typical examples thereof include a double domain TN (twisted nematic), an axially symmetric aligned microcell (ASM), an optically compensated blend ), VA (vertical alignmnt), MVA (multidomain VA), SE (surrounding electrode), PVA (patterned VA), IPS (in-plane switching) and FFS (fringe-field switching) modes. Each of these modes has a unique liquid crystal arrangement and has inherent optical anisotropy.

Therefore, in order to manifest the phase difference due to the optical anisotropy of these liquid crystal modes, an optically anisotropic phase difference film corresponding to each mode is required. In particular, since the liquid crystal having a positive dielectric anisotropy is horizontally aligned in the IPS mode, the optical anisotropy in the non-driven state is not greater than the other modes, which is advantageous in that an excellent viewing angle can be secured even by using the isotropic protective film alone . In this case, however, compensation for the absorption axis of the polarizer at the high inclination angle is not performed at all, so that the contrast may be deteriorated due to the viewing angle and color modulation may occur. Therefore, in order to secure a perfect viewing angle, the IPS mode liquid crystal display should also use an appropriate retardation film do.

The structure in which the retardation film for IPS mode is composed of two or more layers of layers is practically presented. In order to realize a multilayer film, a method of laminating each different film using an adhesive is proposed. Alternatively, a process of coating a liquid crystal or a material exhibiting a phase difference after a stretched film is prepared through a separate stretching process is separately performed.

However, when the adhesive layer is laminated 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 films to be laminated are not precisely arranged, the desired retardation characteristics are not exhibited. When a step of coating a liquid crystal after the stretched film is formed through a stretching process is separately performed, various steps such as a separate alignment step are performed, which complicates the manufacturing process and increases manufacturing cost.

In addition, when organic materials are coated with a material exhibiting a retardation, curl may occur, or substrate phase erosion due to an organic solvent may cause a phase difference of the base film to change.

Therefore, there is a demand for a phase difference film and a manufacturing method thereof which are excellent in the viewing angle improving effect when applied to an IPS mode liquid crystal display device, can be manufactured in a thin shape, and can be manufactured by a simple process.

Korean Unexamined Patent Publication No. 2005-0101743

The present invention is to provide a coating liquid composition, a coating layer formed using the coating liquid composition, a retardation film including the coating layer, and a liquid crystal display device including the retardation film.

The present invention provides a coating liquid composition comprising a layered inorganic material, a water-dispersible urethane-based resin and a solvent, wherein the water-dispersible urethane-based resin comprises an aliphatic unit.

In one aspect of the present invention, the layered inorganic material may include one or more selected from the group consisting of smectite series.

Specifically, the layered inorganic material may include one or more selected from the group consisting of hectorite, montmorillonite, and bentonite.

In another aspect, the layered inorganic material has an average diameter of 10 nm to 30 nm and a thickness of more than 0 nm and 2 nm or less.

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

In another embodiment of the present specification, the layered inorganic material is represented by the following structural formula 1. < EMI ID = 1.0 >

[Structural 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 invention, the content of the layered inorganic material and the water-dispersible urethane resin is 4 wt% to 15 wt%, and the content of the solvent is 85 wt% to 96 wt%, based on the total weight of the coating liquid composition.

In one embodiment of the present disclosure, the solvent comprises water.

In another embodiment, the solvent further comprises one or more solvents selected from the group consisting of alcohols and ketones.

In one embodiment of the present invention, the content of water is 50 wt% to 100 wt% with respect to the total weight of the solvent, and the content of one or more solvents selected from the group consisting of alcohols and ketones is 0 By weight to 50% by weight.

In another embodiment, the layered inorganic material is dispersed in the water.

In one embodiment of the present invention, the elongation percentage of the water-dispersible urethane-based resin is 50% or more.

In another aspect of the present disclosure, there is provided a coating layer formed using the above-described coating liquid composition.

In one embodiment, the coating layer is a -C-plate.

In yet one embodiment, the thickness retardation value of the film measured at a wavelength of 550nm which is represented by the following formula (1) of the coating layer (R _th) is -400 nm to 0 nm.

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

In the formula (1)

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

n _x is a refractive index in a direction in which the surface direction refractive index of the coating layer becomes maximum,

n _z means the refractive index in the thickness direction,

d means the thickness of the coating layer.

In one embodiment of the present invention, the thickness of the coating layer is preferably in the range of more than 0 to 20 占 퐉.

The present specification also provides a retardation film comprising the above-mentioned coating layer.

The disclosure also relates to a substrate film comprising a negative birefringent material; And a coating layer provided on at least one surface of the base film, wherein the coating layer satisfies the following formulas (2) to (4).

(2): 50 nm? R _in ? 300 nm

Equation (3): 10 nm ≤ R th ≤ 300 nm

Equation (4): 0.1? Nz <1

In the above formulas (2) to (4)

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

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

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

In one aspect of the present invention, the base film comprises an acrylic resin; Styrene type resin; And a copolymer comprising an acrylic monomer and a styrene monomer.

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

In another aspect of the present invention, the thickness of the base film is preferably 80 占 퐉 or less.

In one embodiment of the present invention, the base film and the coating layer are provided in contact with each other.

The present specification provides a polarizing plate comprising the above-described retardation film.

The present specification also provides a polarizing plate comprising the above-described composite retardation film.

Finally, the present invention provides an IPS mode liquid crystal display including the above-mentioned polarizing plate.

The retardation film according to one embodiment of the present disclosure has a retardation property suitable for use as an IPS mode retardation film, and thus has an excellent viewing angle improving effect when applied to an IPS mode retardation film.

Further, the retardation film according to one embodiment of the present invention is economical in terms of time and / or cost of manufacture since it does not require a separate pressure-sensitive adhesive layer.

In addition, the phase difference film according to one embodiment of the present invention does not require a separate alignment process, and therefore, the manufacturing method is very simple as compared with the conventional method of coating liquid crystal and phase contrast material.

Further, since the retardation film according to one embodiment of the present invention does not require a step of laminating using a pressure-sensitive adhesive, there is no decrease in optical characteristics or deviation of retardation axes due to the presence of the pressure-sensitive adhesive layer.

In addition, the retardation film according to one embodiment of the present invention has an advantage that occurrence of defects such as curl is minimized.

1 is a view illustrating an IPS mode liquid crystal display according to an embodiment of the present invention.
Fig. 2 is a chart comparing the occurrence of curls in Example 1 and Comparative Example 3. Fig.

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

First, terms used in this specification are defined.

(1) When a member is referred to herein as being "on " another member, it includes not only a member in contact with another member but also another member between the two members.

(2) Whenever a part is referred to as "including " an element in this specification, it is to be understood that it may include other elements as well, without departing from the other elements unless specifically stated otherwise.

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

In addition, n _x , n _y , and n _z mean values measured at a wavelength of 550 nm. On the other hand, the n _x, n _y, n _z can be measured by a method known well-known in the art and, for example, the mean refractive index by using a prism coupler devices (SAIRON TECHNOLOGY社SPA-3DR) measuring, measuring a birefringence aekso scan (Axoscan) of Axomatrics社, we can calculate the n _x, n _y, n _z, respectively.

(4) In the present specification, R _in denotes a plane retardation value measured with light having a wavelength of 550 nm, and the retardation value R _in = (n _x - n _y ) x d. Here, n _x and n _y are the same as described above, and d means the thickness of the optical film. On the other hand, _in the R it can be measured by a known method known in the art and, for example, can be measured using the equipment of Axoscan Axomatrics社.

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

6 that in the present specification means the ratio Nz of the retardation value in the thickness direction to the retardation value in the plane direction is obtained by Nz = R _th / R _in.

7, the negative birefringence material is then stretched (after alignment), the optical axis in a direction perpendicular to the stretching direction in this specification means the substance expressing (plane direction refractive index is the maximum refractive index of the direction in which the n _x), and Refers to a material that exhibits a refractive index distribution of n _z > n _x = n _y when coated (only before stretching). Definition: A birefringent material is a material that expresses an optical axis in a direction parallel to a stretching direction after stretching (after orientation). When a coating is performed only (before stretching), a refractive index distribution of n _x = n _y > n _z is expressed Of the substance.

(8) In the present specification, the thickness means an average width between one surface of a member and a surface facing the surface.

(9) 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 . _Nx , _ny, and _nz are the same as described above.

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

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, embodiments of the present disclosure are provided to more fully describe the present disclosure to those skilled in the art.

&Lt; Coating liquid composition &

The present invention provides a coating liquid composition comprising a layered inorganic material, a water-dispersible urethane-based resin and a solvent, wherein the water-dispersible urethane-based resin comprises an aliphatic unit.

When a coating layer is formed using a coating liquid composition containing a layered inorganic material as in the embodiment of the present invention, the occurrence of curl is minimized, and a desired retardation film can be realized even with a thin layer thickness.

In addition, the coating liquid composition according to one embodiment of the present disclosure can improve the adhesion of the layered inorganic material as well as the water-dispersed urethane-based resin to the other member and prevent the layer from being broken.

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

According to one embodiment of the present invention, the layered inorganic material may be one 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 a compound having a crystal structure similar to these.

In one embodiment of the present invention, 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 layered inorganic material has an average diameter of 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 disk-shaped disk. The average diameter may mean the average diameter of the cross section of the plate, and the thickness may mean the distance between the lower surface and the upper surface of the layered inorganic material. The above average diameter and thickness can be measured by a method used in the art.

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

[Structural 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 invention, the layered inorganic material has a structure represented by the structural formula 1 in terms of phase retardation, transparency, dispersion with a water-dispersed binder, swelling between layers, exchangeability of cations, and / More preferable.

In one embodiment of the present invention, the layered inorganic material may be dispersed in water. That is, the layered inorganic material according to one embodiment of the present invention may be selected from one or more of water-dispersible layered inorganic materials.

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

In this specification, the coating liquid composition includes an aqueous dispersion urethane-based resin. According to one embodiment of the present invention, the water-dispersed urethane-based resin contained in the coating layer can prevent cracking due to the layered inorganic material and improve adhesion between the other member and the coating layer.

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

As described above, when the water-dispersible urethane-based resin is used, environmental pollution due to the release of harmful solvents can be prevented, and the stability of the particles in the aqueous dispersion phase is excellent. In addition, when a water-dispersible resin is used, it is possible to prevent the phase difference of the substrate film from changing due to substrate erosion due to an organic solvent.

In one embodiment of the present invention, the content of the layered inorganic material and the water-dispersible urethane resin is 4 wt% to 15 wt%, and the content of the solvent is 85 wt% to 96 wt%, based on the total weight of the coating liquid composition.

In one embodiment, the solid content of the coating liquid composition is 4 wt% to 15 wt%, and the solvent content is 85 wt% to 96 wt%.

In this specification, when the content of the solid content in the coating liquid composition is more than 15% by weight, the inorganic material is not well dispersed and the viscosity is too high, so that uniform coating is difficult to cause unevenness of phase difference and / have. If the content of the solid content is less than 4% by weight, the viscosity may be low, causing a problem of flowing during coating, lowering the drying efficiency, and reducing the area of the coating layer to be obtained relative to the amount of the coating solution.

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

As used herein, the term solids refers to solutes or solids excluding the solvent in the total mass of the solution. The solid content in the coating liquid composition of the present specification may mean a layered inorganic material and an aqueous dispersion urethane-based resin.

In one embodiment, the solvent comprises water.

In another embodiment, the solvent is selected from the group consisting of alcohols such as ethanol and methanol; And ketones such as acetone, methyl ethyl ketone (MEK), and the like.

In one embodiment of the present invention, the content of water may be 85 wt% to 96 wt% based on the total weight of the coating liquid composition.

In one embodiment of the present invention, the content of water is 50 wt% to 100 wt% with respect to the total weight of the solvent, and the content of one or more solvents selected from the group consisting of alcohols and ketones is 0 By weight to 50% by weight.

In one embodiment of the present invention, the content of one or more solvents selected from the group consisting of alcohols and ketones is preferably 0 wt% to 20 wt% based on the total amount of the water.

When the content of water in the total content of the solvent is 50% by weight or more as in the embodiment of the present specification, erosion of the substrate due to the use of the organic solvent is prevented and deformation of the retardation due to erosion of the substrate can be prevented . In addition, it is possible to minimize the occurrence of curling of the coating layer formed by using the coating liquid composition, thereby effectively increasing the viewing angle compensation effect, improving the durability, and preventing defects occurring during the lapping process with other members. In view of the above, the content of water in the entire solvent is preferably 70% by weight or more, more preferably 80% by weight or more.

In another embodiment of the present invention, the water content of the coating liquid composition is 75 wt% to 96 wt%, and the content of one or more solvents selected from the group consisting of alcohols and ketones is 0 By weight to 10% by weight.

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

In the present specification, the "aliphatic unit" may mean a structure that does not include an aromatic structure such as benzene as a structural unit. When the aromatic structure is not included, it is not limited to a straight chain, a branched chain, or a ring, but may be composed of only hydrocarbon, but may contain a heteroatom unless the effect of the invention is impaired.

Saturated aliphatic units such as methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl, hexyl, heptyl, cyclopentyl and cyclohexyl; Unsaturated aliphatic units such as vinyl, 1-propenyl, isopropenyl, cyclohexenyl, and the like. In the above-mentioned examples, a carbon atom may be substituted with a hetero atom such as S, O, have.

As used herein, the urethane-based resin is a structure having a urethane bond in a molecule, and may be produced by a method known in the art, for example, by reacting a diisocyanate (-NCO) with a polyol, .

The urethane resin in the present specification may contain an urethane monomer of "-O- (C═O) -NH-R-HN- (C═O) -O-", and may further contain additional monomers . The R may be a divalent aliphatic unit.

In one aspect of the present specification, in the toughness aspect, it is preferable that R is an alicyclic structure or a straight-chain saturated aliphatic unit.

Specifically, the water-dispersible urethane-based resin according to one embodiment of the present specification may be a resin containing only the above-mentioned urethane monomer.

The water-dispersible urethane-based resin according to another embodiment may be a copolymer comprising the above-mentioned urethane monomer and further monomers.

The additional monomers include, but are not limited to monomers known in the art, monomers comprising a carbonate group (-O- (C = O) -O-); Ester "(ester "-( C = O) -O-"); And an ether group ("-O-"), may be used alone or in combination of two or more.

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

In one embodiment of the present invention, the water-dispersible urethane-based resin comprises an urethane monomer containing an aliphatic unit; Or a copolymer of an urethane monomer containing an aliphatic unit and one or more monomers selected from the group consisting of a monomer containing a carbonate group, a monomer containing an ester group and a monomer containing an ether group.

In one embodiment of the present invention, the elongation percentage of the water-dispersible urethane-based resin is 50% or more. In this case, the coating layer formed using the coating liquid composition according to one embodiment of the present invention can be prevented from being broken, and durability can be improved. In addition, excellent effects can be expected in terms of toughness and adhesion to other members.

In this specification, the elongation means a rate at which the material is stretched during the material tensile test, and the elongation can be measured by a method known in the art.

According to one embodiment of the present invention, the coating liquid composition may include the layered inorganic material and the water-dispersible urethane-based binder resin in a weight ratio of 1: 0.6 to 1: 2.

When the weight ratio of the layered inorganic material and the water-dispersible urethane binder resin is within the above range, it is advantageous to prevent cracking of the layer, and the mechanical characteristics of the retardation film for IPS mode liquid crystal display can be improved.

&Lt; Coating layer &

One embodiment of the present invention provides a coating layer formed using the above-described coating liquid composition. In this specification, the coating liquid composition is the same as described above.

In one embodiment of the present disclosure, the coating layer is a -C-plate. In this case, the coating layer can be introduced into the base film of the + B plate to manifest the optical characteristics required in the IPS mode liquid crystal display device phase retardation film, and a high viewing angle compensation performance can be provided.

In another embodiment, the coating layer may be formed by a method known in the art, for example, by dispersing the layered inorganic material in water, mixing and coating with an aqueous dispersion urethane binder resin, and drying .

In this specification, the coating layer may be formed by a method known in the art. For example, a method of forming a coating layer directly on the base film may be used, or by using an adhesive or an adhesive after forming the coating layer However, the direct coating method is economical in terms of time and cost of the process, and is preferable from the viewpoint of phase difference manifestation.

On the other hand, the method of forming the coating layer directly on the base film is not particularly limited, and any method known in the art may be used. For example, a bar coating, a slot die coating, a spray coating, Coating, dip coating, micro gravure coater, comma coater and the like can be used.

In one embodiment, the thickness direction retardation value (R _th ) of the coating film measured at a wavelength of 550 nm represented by the following formula (1) is -400 nm to 0 nm. In the case of the coating layer having the retardation value in the thickness direction, it can be very usefully used as a retardation film for an IPS mode liquid crystal display device together with a base film described later. In one embodiment of the present disclosure, that the one (R _th) in the thickness direction retardation value of the film measured at a wavelength of 550nm of the coating of -120 nm to -100 nm is more preferred.

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

In the formula (1)

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

n _x is a refractive index in a direction in which the surface direction refractive index of the coating layer becomes maximum,

n _z means the refractive index in the thickness direction,

d means the thickness of the coating layer.

According to another embodiment of the present invention, the thickness of the coating layer is more than 0 to 20 占 퐉. More preferably more than 0 and 15 mu m or less. When the thickness of the coating layer is in the above range, problems such as drying failure, curling of the film and the like can be minimized and the display can be thinned.

< Phase difference  Film and composite Phase difference  Film>

The present invention provides a retardation film comprising the coating layer.

The present disclosure relates to a substrate film comprising a negative birefringent material; And the above-described coating layer provided on at least one surface of the base film, wherein the composite retardation film satisfies the above-mentioned formulas (2) to (4). In this case, it can be very usefully used as a retardation film for an IPS mode liquid crystal display.

In one embodiment of the present invention, the retardation film is for an IPS mode liquid crystal display.

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

It is also preferable that the retardation film has an Nz value of 0.2 to 0.9.

Conventionally, a polymer material such as a polyamide, a cyclic olefin-based polymer, a polycarbonate, a polyarylate, or an imide-based polymer has been used as a material of a layer provided on at least one surface of the base film. In this case, There was a problem in that a curl occurred. The occurrence of curl hinders efficient implementation of the viewing angle compensation effect, and may cause deterioration of the durability and the like of the liquid crystal display device including the curl. Further, it may cause defects such as wrinkles in the lapping process with other members.

Therefore, when a coating layer containing a layered inorganic material is included on at least one surface of a base film as in the embodiment of the present invention, the occurrence of curl is minimized and the desired phase difference can be realized even with a thin layer thickness have.

In addition, the retardation film according to one embodiment of the present invention can improve the adhesion to the base film and prevent the base film from being broken by including a layered inorganic material as well as an aqueous dispersion urethane resin in the coating layer.

In this specification, the coating layer of the retardation film is the same as described above.

- base film

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

In one embodiment of the present invention, the base film comprises an acrylic resin; Styrene type resin; And copolymers comprising an acrylic monomer and a styrene monomer.

Specifically, in one embodiment of the present specification, the base film comprises an acrylic resin; A blend resin of an acrylic resin and a styrene resin; Or a copolymer comprising an acrylic monomer and a styrene monomer.

As used herein, the term "blend resin" means mixing two or more resins, and "copolymer" may mean one polymer formed by polymerizing two or more monomers.

In the present specification, the acrylic resin mainly contains an acrylate monomer and / or a methacrylate monomer, and includes not only a homopolymer resin composed of an acrylate monomer or a methacrylate monomer, but also an acrylate monomer and / Or a copolymer resin in which other monomers other than the methacrylate monomer are copolymerized.

Herein, the methacrylate monomer includes 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. Of these, methyl methacrylate is more preferable, but is not limited thereto. These may be used alone or in combination.

In addition, the acrylate monomer includes not only an acrylate but also an acrylate derivative. Examples of the acrylate monomer include methyl acrylate, ethyl acrylate, propyl acrylate, n -butyl acrylate, t -butyl acrylate, cyclohexyl acrylate Methoxyethyl acrylate, ethoxyethyl acrylate, butoxymethyl acrylate, and oligomers thereof. Of these, methyl acrylate is more preferable, but is limited thereto. It is not. These may be used alone or in combination.

In the present specification, the styrene-based resin includes a styrene-based monomer, and examples thereof include, but are not limited to, styrene,? -Methylstyrene, and 4-methylstyrene.

The styrenic monomer is preferably prepared in a copolymerized form with an acrylic monomer, but alternatively, a separate styrenic copolymer may be blended with a polymer comprising the acrylic monomer. For example, the copolymer containing the acrylic monomer and the styrene monomer may be a styrene-maleic anhydride copolymer (SMA), a styrene-acrylonitrile copolymer (SAN), an a-methylstyrene-acrylonitrile copolymer ), But the present invention is not limited thereto.

On the other hand, in order to improve the heat resistance, the acrylic resin may include a lactone monomer, a maleic anhydride monomer, a maleimide monomer, or the like, other than the (meth) acrylic monomer. Examples of the maleic anhydride monomer include maleic anhydride, methyl maleic anhydride, ethyl maleic anhydride, propyl maleic anhydride, isopropyl maleic anhydride, cyclohexyl maleic anhydride and phenyl maleic anhydride. ; Examples of the maleimide-based monomer include maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, But are not limited thereto. These may be used alone or in combination.

In another embodiment, in the case where a blend resin of an acrylic resin and a styrene resin is used as the base film, a high heat resistance of the acrylic resin and a high retardation of the styrene resin can be expected.

The glass transition temperature (Tg) of the base film is preferably 100 ° C to 160 ° C. When the glass transition temperature (Tg) is in the above range, it can have excellent durability. If the glass transition temperature is less than 100 ° C, the film is easily deformed under high temperature and high humidity conditions, There is a problem that this becomes uneven.

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

In another embodiment, the thickness direction retardation value (R _th ) of the base film measured at a wavelength of 550 nm is 150 nm to 160 nm.

The retardation value in the plane direction and the retardation value in the thickness direction can be calculated by the above-described method.

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

The uniaxial or biaxial stretching may be performed by a method known in the art. For example, the stretching may be performed in a tenter equipped with a preheating portion, a stretching portion and a heat treatment portion. The term "preheating" refers to a process of softening the substrate film by heating in advance so that it can be satisfactorily stretched in a subsequent stretching process. The substrate film introduced into the preheating device is heated at a temperature lower than Tg, The stretching process 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 section. At this time, the stretching magnification can be adjusted in the stretching portion according to the phase difference value to be acquired.

According to one embodiment of the present disclosure, the base film is a + B plate.

According to one embodiment of the present invention, the thickness of the base film is 80 mu m or less. Specifically, it may be 70 mu m or less or 60 mu m or less. More specifically, it may be more than 0 [mu] m but not more than 50 [mu] m. In one embodiment of the present invention, the thickness of the base film may be 30 占 퐉 to 40 占 퐉.

The phase difference film according to an exemplary embodiment of the present specification may be satisfied a relation of _{n x, total> n z,} total> n y, total.

n _{x, total} is the refractive index in the direction in which the refractive index in the plane direction of the entire retardation film becomes maximum (that is, in the slow axis direction)

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

n _{z and total} are refractive indices in the thickness direction of the entire retardation film.

In one embodiment of the present invention, the base film and the coating layer are provided in contact with each other. That is, in one embodiment of the present specification, the base film and the coating layer provide an integral complex phase difference film.

That is, the retardation film according to one embodiment of the present disclosure may not include additional members such as a primer layer, an adhesive layer, and a pressure-sensitive adhesive layer between the base film and the coating layer. This is because the water-dispersible urethane-based resin contained in the coating layer improves the adhesion as described above.

In this case, the influence due to external stress can be minimized owing to the additional member, and deterioration of the optical characteristics can be prevented. Further, the film can be made thinner easily, and the production process and cost are easy.

In another embodiment, it may further comprise an additional member between the base film and the coating layer.

In one embodiment of the present invention, the total thickness of the base film and the retardation film including the coating layer may be 20 탆 to 100 탆, but is not limited thereto. When the thickness of the polarizer is less than 20 탆, the retarder film does not firmly support the polarizer, and therefore, there is a high possibility that the polarizer shrinkage, the polarizer crack, curl and the like are likely to occur. When the thickness exceeds 100 탆, There is a problem in that defects are caused by drying failure of the ink.

On the other hand, in the production of the retardation film according to one embodiment of the present invention, if necessary, it may further include additives known in the art. Examples of the additive include, but are not limited to, a dispersant, a surface additive, a lubricant, a heat stabilizer, a UV absorber, a plasticizer and an antioxidant. &Lt; / RTI &gt;

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

The above-mentioned base film, the layered inorganic material contained in the coating layer, and the water-dispersed urethane-based resin are the same as described above.

One embodiment of the present disclosure also provides a polarizing plate comprising the above-described retardation film. At this time, the polarizing plate may have a component, a lamination sequence, and the like known in the art, except that the polarizing plate includes a retardation film according to one embodiment of the present disclosure. For example, a protective film or the like may further be included.

Specifically, it may be a polarizing plate comprising a retardation film according to one embodiment of the present invention on at least one side of a polyvinyl alcohol-based polarizer.

One embodiment of the present disclosure also provides an IPS mode liquid crystal display device including the above-mentioned polarizing plate.

The IPS mode liquid crystal display may include a liquid crystal cell and a first polarizing plate and a second polarizing plate disposed on both sides of the liquid crystal cell. The retardation film for the IPS mode liquid crystal display may include a liquid crystal cell, Or between the first polarizing plate and the second polarizing plate. That is, the retardation film may be provided between the first polarizer and the liquid crystal cell, between the second polarizer and the liquid crystal cell, or between the first polarizer and the liquid crystal cell, between the second polarizer and the liquid crystal cell One or two or more .

The first polarizing plate and the second polarizing plate may further include a protective film on one surface or both surfaces thereof. For example, the inner protective film may be a triacetate cellulose (TAC) film, a polynorbornene-based film produced by an acrylic film ring opening metathesis polymerization (ROMP) A ring opening metathesis polymerization followed by hydrogenation (HROMP) polymer film obtained by hydrogenating a ring-opening polymerized cyclic olefin polymer, a polyester film, or a polynorbornene-based film produced by addition polymerization. In addition, a protective film or the like made of a transparent polymer material may be used, but is not limited thereto.

Further, a surface coating layer may be further included on the protective film. The surface treatment layer may be a low reflection layer such as an anti-glare layer or an anti-reflection (AR) layer or a low reflection (LR) layer such as a hard layer, an anti-glare layer or a semi- Can be illustrated.

Hereinafter, the present invention will be described in more detail by way of examples. However, the following embodiments are intended to illustrate the present disclosure, and thus the scope of the present specification is not limited thereto.

< Example  1>

A coating liquid composition prepared by mixing 3.0 wt% of hectorite, laponite (BYK), and 3.6 wt% of R600 (DSM), an aqueous dispersion-based resin, in distilled water was applied to a base plate A coating layer of -C plate was coated on a FN-A film (Okura) using a bar coater and dried at 100 ° C for 5 minutes to prepare a retardation film.

< Example  2>

A retardation film was prepared in the same manner as in Example 1, except that 2.1 wt% of trade name 460S (DKS), which is an aqueous dispersion urethane resin, was used in place of R600.

< Comparative Example  1>

The same procedure as in Example 1 was carried out except that laponite, which is a hectorite, was not used and 6.6 wt% of a water-dispersible urethane resin, trade name R600 (DSM), was dispersed in distilled water To prepare a retardation film.

< Comparative Example  2>

Except that the coating liquid composition in which 5.1 wt% of 460S (Dai-ichi Kogyo Seiyaku Co., Ltd.) dispersed in water-dispersed urethane binder was used in distilled water without using hectorite laponite (BYK) A retardation film was prepared in the same manner as in Example 1.

< Comparative Example  3>

A mixture of toluene and methyl ethyl ketone (MEK) (3: 2) was mixed with a polyarylate resin, trade name M2040 (Unitika), without using hectorite laponite (BYK) A retardation film was prepared in the same manner as in Example 1, except that the coating liquid composition was dissolved in 13 wt% in a solvent.

< Comparative Example  4>

(Solvent: 1,3-dioxolane (1, 3-dioxolane) (1) in which 18 wt% of thermoplastic polyimide (Sabic, XH6050) was contained without using hectorite laponite 3-dioxolane) was used as a retardation film.

< Comparative Example  5>

A coating liquid composition (solvent: methylene chloride) containing 3 wt% of Lucentite SPN (kobo) instead of laponite (hectorite) was used instead of the water-dispersed urethane binder. ) Was used as a retardation film, a retardation film was produced in the same manner as in Example 1.

< Comparative Example  6>

Except that the coating liquid composition in which 2.75 wt% of laponite (BYK Co.), which is a hectorite, was dispersed in distilled water without using a water-dispersed urethane binder was used, and in the same manner as in Example 1, .

< Comparative Example  7>

A retardation film was prepared in the same manner as in Example 1, except that 3.0 wt% of trade name Al127 as an aqueous dispersion acrylic resin instead of R600 was used.

< Comparative Example  8>

A retardation film was prepared in the same manner as in Example 1, except that 3.0 wt% AP40F (Dainippon Ink and Chemical Co.), which is an aqueous dispersion-based urethane resin containing an aromatic group, was used instead of R600.

< Experimental Example >

The thickness, R _in , R _th , and adhesion of the retardation film prepared according to Examples 1 and 2 and Comparative Examples 1 to 8 are summarized in Table 1 below. The thickness of the base film as the + B plate used in Examples 1 and 2 and Comparative Examples 1 to 8 is all 35 占 퐉, R _in is 110 nm, and R _th is 160 nm.

Coating layer Whole phase difference film Thickness (㎛) R _in (nm) R _th (nm) Thickness (㎛) R _in (nm) R _th (nm) Attachment Example 1 10 0 -101 45 110 59 OK Example 2 7 0 -110 42 110 50 OK Comparative Example 1 10 0 -One 45 110 159 OK Comparative Example 2 7 0 -3 42 110 157 OK Comparative Example 3 6 2 -90 41 95 55 OK Comparative Example 4 4 0 -98 39 2 -5 Substrate erosion Comparative Example 5 5 0 -64 39 2 -7 Substrate erosion Comparative Example 6 2 0 -78 37 110 82 Coating layer brittle Comparative Example 7 7 0 -91 42 110 69 Coating layer cracked and peeled Comparative Example 8 4 0 -102 39 110 58 Coating layer cracked and peeled

In Table 1, the adhesion between the coating layer and the base film was evaluated by attaching a sheath to the coated surface of the coated retardation film and evaluating the adhesion while stripping using 3M tape.

As a result of the above Table 1, it was confirmed that the coating layer itself was broken in the case of Comparative Example 6 which did not contain the water-dispersed urethane binder but only the layered inorganic material, and instead of the water-dispersed urethane binder containing aliphatic units, In the case of Comparative Example 7 using an acrylic resin and Comparative Example 8 using an aqueous dispersion urethane binder containing an aromatic unit, it was confirmed that the coating layer was easily broken and peeling occurred in the base film.

Further, in the case of Comparative Examples 1 and 2 which did not contain a layered inorganic material but contained a water-dispersible urethane binder, the value of the formula (4) of 0.1? Nz <1 could not be satisfied and the retardation for the IPS mode liquid crystal display device Can not be confirmed.

Not including the layered inorganic material and the water dispersed urethane, poly arylate-based resin and that of Comparative Example 3 using an organic solvent, due to the erosion of the base film with an organic solvent, if the retardation value of the composite retardation film (R _in ) Was decreased and curl was observed.

Fig. 2 is a chart comparing the occurrence of curls in Example 1 and Comparative Example 3. Fig. From the results of FIG. 2, it can be confirmed that when a coating layer is formed using the coating liquid composition according to one embodiment of the present invention, curling is prevented.

Finally, a coating solution composition was prepared in the same manner as in Comparative Example 4 using a coating liquid composition comprising an organic solvent and a binder resin (polyimide (Sabic, XH6050)) and an organic solvent and a layered inorganic material (Lucentite SPN In the case of using a solvent, erosion of the base film occurs and it can be confirmed that the retardation value (R _in ) _in the plane direction of the composite retardation film decreases.

As a result, when the layered inorganic material and the water-dispersible urethane-based resin containing an aliphatic unit are simultaneously contained according to one embodiment of the present invention, a retardation corresponding to the retardation film for the IPS mode liquid crystal display device is expressed, It is easy to prevent the occurrence of curling, prevent cracking due to the layered inorganic material, and improve adhesion with other members.

In addition, the coating liquid composition according to an embodiment of the present invention can prevent erosion of the substrate by using water instead of an organic solvent, and can prevent curling by using a layered inorganic material instead of the organic polymer.

801: Surface coating layer
701: Protective film
601: Polarizer
501: primer layer
401: base film
301: Coating layer
201: pressure-sensitive adhesive layer
101: IPS panel

Claims (24)

A layered inorganic material, a water-dispersed urethane-based resin and a solvent,
Wherein the water-dispersible urethane-based resin comprises an aliphatic unit. The method according to claim 1,
Wherein the layered inorganic material comprises at least one selected from the group consisting of smectite-based materials. The method according to claim 1,
Wherein the layered inorganic material comprises one or more selected from the group consisting of hectorite, montmorillonite, and bentonite. The method according to claim 1,
The average diameter of the layered inorganic material is 10 nm to 30 nm,
And the thickness is more than 0 nm but not more than 2 nm. The method according to claim 1,
Wherein the layered inorganic material is in the form of a plate-like disk. The method according to claim 1,
Wherein the layered inorganic material is represented by the following structural formula (1).
[Structural formula 1]
^{_{Na + 0.7 [(Si 8 Mg}} 5.5 Li 0.3) O 20 (OH) 4] -0.7 The method according to claim 1,
The content of the layered inorganic material and the water-dispersed urethane-based resin is 4 wt% to 15 wt% based on the total weight of the coating liquid composition,
And the content of the solvent is 85 wt% to 96 wt%. The method according to claim 1,
Wherein the solvent comprises water. The method of claim 8,
Wherein the solvent further comprises one or more solvents selected from the group consisting of alcohols and ketones. The method of claim 9,
The content of the water relative to the total weight of the solvent is 50 wt% to 100 wt%
The content of one or more solvents selected from the group consisting of alcohols and ketones is 0 wt% to 50 wt%. The method of claim 8,
Wherein the layered inorganic material is dispersed in the water. The method according to claim 1,
Wherein the water dispersed urethane resin has an elongation of 50% or more. A coating layer formed using the coating liquid composition according to any one of claims 1 to 12. 14. The method of claim 13,
Wherein the coating layer is a -C-plate. 14. The method of claim 13,
Wherein the thickness direction retardation value (R _th ) of the film measured at a wavelength of 550 nm represented by the following formula (1) in the coating layer is -400 nm to 0 nm:
(1): R _th = (n _z - n _y ) x d
In the formula (1)
n _y is the refractive index in the vertical direction in the n _x direction in the plane direction of the coating layer,
n _x is a refractive index in a direction in which the surface direction refractive index of the coating layer becomes maximum,
n _z means the refractive index in the thickness direction,
d means the thickness of the coating layer. 14. The method of claim 13,
Wherein the thickness of the coating layer is greater than 0 and 20 占 퐉 or less. A retardation film comprising a coating layer according to claim 13. A substrate film comprising a negative birefringent material; And
And a coating layer according to claim 13 provided on at least one side of the base film,
A composite retardation film satisfying the following formulas (2) to (4):
(2): 50 nm? R _in ? 300 nm
Equation (3): 10 nm ≤ R th ≤ 300 nm
Equation (4): 0.1? Nz <1
In the above formulas (2) to (4)
R _in is the retardation value in the plane direction of the film measured at a wavelength of 550 nm,
R _th is the thickness direction retardation value of the film measured at a wavelength of 550 nm,
Nz is the ratio (R _th / R _in) of the thickness retardation value on a plane direction retardation value measured at a wavelength of 550nm. 19. The method of claim 18,
The base film may be an acrylic resin; Styrene type resin; And a copolymer comprising an acrylic monomer and a styrene monomer. 19. The method of claim 18,
Wherein the base film is a + B plate. 19. The method of claim 18,
Wherein the base film has a thickness of 80 占 퐉 or less. 19. The method of claim 18,
Wherein the base film and the coating layer are provided in contact with each other. A polarizer comprising the composite retardation film according to claim 18. An IPS mode liquid crystal display comprising a polarizing plate according to claim 23.

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