KR20210052902A - Polarizing Plate - Google Patents

Abstract

The present application relates to a polarizing plate. The present application may provide the polarizing plate, which can utilize the excellent low moisture permeability characteristics without the occurrence of optical defects, and include a polyester film which is not easily broken or cracked even when bending or the like occurs, and a display device applying the polarizing plate.

Description

Polarizing Plate

The present application relates to a polarizing plate and a display device.

The polarizing plate is an optical film applied to control the state of light in various display devices. Usually, a polarizing plate is manufactured by attaching a protective film to one or both sides of a polarizing film having a polarizing function.

Since the polarizing plate is exposed to various temperature and humidity conditions according to the use environment of the display device, durability is required. For example, the polarizing plate should stably maintain the designed optical properties even according to external environments such as temperature and humidity, and mechanical defects such as cracks should not occur.

Since the polarizing film included in the polarizing plate (in particular, a so-called PVA (poly(vinyl alcohol))-based polarizing film) has a property that is vulnerable to moisture, there is a problem that it is deteriorated when it comes into contact with moisture during use. Therefore, as a protective film laminated on one or both sides of a polarizing film, there is an effort to apply a low moisture permeable material, and a material that is currently widely applied is an acrylic film or a cyclic olefin polymer (COP) film.

Polyester materials represented by PET (poly(ethylene terephthalate)) are known to have far superior low moisture permeability properties than the acrylic film or COP film. However, since the polyester material has a retardation, when applied to a polarizing plate, optical defects called so-called rainbow spots or the like are caused depending on the use environment.

In order to solve the above problems, there is a technology in which a polyester film is manufactured in a high-stretch method to have a higher retardation compared to a conventional case (for example, Patent Document 1).

The prior art as described above can solve the problem of optical defects such as rainbow stains, and utilize the low moisture permeability characteristics of the polyester film.

However, the above film is expensive because it is manufactured by a special process such as a high stretching process, and it is not easy to obtain a product.

In addition, since the above film is manufactured by a high stretching process, for example, when the film is bent with the stretching main axis as an axis, there is a problem that it is easily broken or cracked.

Japanese Patent No. 6521216

The present application provides a polarizing plate and a display device. The object of the present application is to provide a polarizing plate including a polyester film that can utilize excellent low moisture permeability without occurrence of optical defects, and does not easily crack or crack even when bending or the like occurs, and a display device to which the same is applied. do.

Vertical, parallel, orthogonal or horizontal among the terms defining an angle in the present specification means substantially vertical, parallel, orthogonal or horizontal within a range that does not impair the objective effect, and the vertical, parallel, orthogonal or horizontal range Is to include errors such as manufacturing errors or variations. For example, in each of the above cases, an error within about ±15 degrees, an error within about ±10 degrees, or an error within about ±5 degrees may be included.

Optical properties mentioned in the present specification, for example, retardation or refractive index, are properties based on a wavelength of 550 nm, unless otherwise specified.

Among the physical properties mentioned in the present specification, the above properties are properties measured at room temperature unless otherwise specified in the case where the measurement temperature affects the property.

In the present specification, the term room temperature is a temperature in a state that is not particularly warmed or reduced in temperature, and any one temperature within the range of about 10°C to 30°C, for example, about 15°C or more, 18°C or more, 20°C or more, or about 23 It may mean a temperature of about 27°C or less while being equal to or higher than °C. In addition, unless otherwise specified, the unit of temperature referred to in this specification is °C.

Among the physical properties mentioned in the present specification, the physical properties are those measured at normal pressure unless otherwise specified in the case where the measured pressure affects the corresponding physical properties.

In the present specification, the term normal pressure is a natural pressure that is not specifically pressurized or depressurized, and generally refers to a pressure of about 1 atmosphere, such as atmospheric pressure.

Among the physical properties mentioned in the present specification, when the measured humidity affects the corresponding physical property, unless otherwise specified, the physical property is any humidity within the range of about 0 RH% to 100 RH%, for example, about 90 RH. % Or less, about 80 RH% or less, about 70 RH% or less, about 60 RH% or less, about 50 RH% or less, about 40 RH% or less, about 30 RH% or less, about 20 RH% or less, about 18 RH% or less , 15RH% or less, or about 10RH% or less, or about 1 RH% or more, about 2RH% or more, about 5 RH% or more, about 10 RH% or more, about 15 RH% or more, about 20 RH% or more, about 25 RH% These are the properties measured at relative humidity of about 30 RH% or more, about 35 RH% or more, about 40 RH% or more, or about 45 RH% or more. In the above, the unit RH% means that the humidity is relative humidity (unit: %).

Unless otherwise specified, the angle formed by any two directions referred to in the present specification may be an acute angle among an acute or obtuse angle formed by the two directions, or a smaller angle among angles measured in a clockwise direction and a counterclockwise direction. . Accordingly, unless otherwise specified, angles referred to in this specification are positive numbers. However, in some cases, in order to indicate the measurement direction between the angles measured in the clockwise or counterclockwise direction, one of the angles measured in the clockwise direction and the angle measured in the counterclockwise direction is indicated as a positive number, and the other The angle of can also be expressed as a negative number.

This application relates to a polarizing plate. In the present specification, the terms polarizing film and polarizing plate have different meanings. The term polarizing film, for example, refers to a functional element itself exhibiting a polarizing function, such as a PVA (poly(vinyl alcohol))-based film in which anisotropic material such as iodine is adsorbed and oriented, and the polarizing plate is together with the polarizing film. It means a device that includes other elements. Other elements included with the polarizing film in the above may include a protective film of a polarizing film, an antistatic layer, a viewing angle compensation film, a hard coating layer, a retardation film, an adhesive layer, an adhesive layer, or a low reflection layer. , But is not limited thereto.

The polarizing plate of the present application may be applied to various uses and exhibit excellent performance.

For example, the polarizing plate of the present application may have a square shape such as a square or a rectangle, and the ratio (W/L) of the width (W) and the length (L) may be within the range of 1.6 to 2. In this case, the ratio (W/L) may be about 1.65 or more, about 1.7 or more, or about 1.75 or more, or about 1.95 or less, about 1.9 or less, about 1.85 or less, or about 1.8 or less in another example.

In another example, the polarizing plate of the present application may have a square shape such as a square or a rectangle, and the ratio (W/L) of the width (W) and the length (L) may be in the range of 1 to 1.6. In this case, the ratio (W/L) is about 1.05 or more, about 1.1 or more, about 1.15 or more, about 1.2 or more, about 1.25 or more, or about 1.3 or more, or about 1.55 or less, about 1.5 or less, about 1.45 or less. , It may be about 1.4 or less, or about 1.35 or less.

The size of the polarizing plate is a value determined by a specification of a display device to which the polarizing plate is applied, for example, an aspect ratio. The polarizing plate of the present application may exhibit a desired excellent performance regardless of the applied aspect ratio of the polarizing plate.

The polarizing plate is also formed in a different direction of the light absorption axis depending on the application purpose, for example, the mode of the display panel. In general, since the polarizing film in the polarizing plate shrinks along the direction in which the light absorption axis is formed, the direction in which the light absorption axis is formed is also considered in terms of the optical or mechanical durability of the polarizing plate, and in suppressing bending or twisting of the display device to which the polarizing plate is applied. It is a matter. The polarizing plate of the present application exhibits excellent performance regardless of the direction in which the light absorption axis is formed.

For example, the smaller of the angles between the polarizing film or one side of the polarizing plate and the light absorption axis of the polarizing film in the polarizing plate may be in a range of 0 degrees to 10 degrees or in a range of 80 degrees to 100 degrees. In another example, the angle may be 9 degrees or less, 8 degrees or less, 7 degrees or less, 6 degrees or less, 5 degrees or less, 4 degrees or less, 3 degrees or less, 2 degrees or less, or 1 degree or less. In addition, the angle is about 81 degrees or more, 82 degrees or more, 83 degrees or more, 84 degrees or more, 85 degrees or more, 86 degrees or more, 87 degrees or more, 88 degrees or more, 89 degrees or more, or 90 degrees or more, It may be 99 degrees or less, 98 degrees or less, 97 degrees or less, 96 degrees or less, 95 degrees or less, 94 degrees or less, 93 degrees or less, 92 degrees or less, 91 degrees or less, or 90 degrees or less.

In another example, a smaller angle of the angle formed between the polarizing film or the one side of the polarizing plate and the light absorption axis of the polarizing film in the polarizing plate may be in a range of 35 degrees to 55 degrees or a range of 125 degrees to 145 degrees.

In other examples, the angle is about 36 degrees or more, 37 degrees or more, 38 degrees or more, 39 degrees or more, 40 degrees or more, 41 degrees or more, 42 degrees or more, 43 degrees or more, 44 degrees or more. Degree or about 45 degrees or more, about 54 degrees or less, 53 degrees or less, 52 degrees or less, 51 degrees or less, 50 degrees or less, 49 degrees or less, 48 degrees or less, 47 degrees or less, 46 degrees It may be less than or equal to 45 degrees, and also about 126 degrees or more, 127 degrees or more, 128 degrees or more, 129 degrees or more, 130 degrees or more, 131 degrees or more, 132 degrees or more, 133 degrees or more Degree, 134 degrees or more, 135 degrees or more, 144 degrees or less, 143 degrees or less, 142 degrees or less, 141 degrees or less, 140 degrees or less, 139 degrees or less, 138 degrees or less, 137 degrees It may be about less than, about 136 degrees or less, or about 135 degrees or less.

In general, the polarizing film and the polarizing plate are square, such as a square or a rectangle, and one side of the polarizing film or polarizing plate forming the angle with the light absorption axis may be any one side of the square. For example, if the rectangle is a rectangle, the one side may be a long side or a short side of the rectangle.

The polarizing plate of the present application may basically include a polarizing film and an optical film formed on one or both sides of the polarizing film. The optical film may be a protective film for the polarizing film. When the optical films are formed on both sides of the polarizing film, the two optical films may be the same or different films, but at least one film is an optical film of the present application to be described later. In one example, at least the outer optical film is the optical film of the present application. In the above, the outer optical film means an optical film positioned farther from the device than the polarizing film when the polarizing plate is applied to a device such as a display device. Thus, for example, if the polarizing plate is a so-called viewer-side polarizing plate, the optical film of the present application is disposed at least on the viewer side than the polarizing film. For example, if a pressure-sensitive adhesive layer or an adhesive layer is included in the polarizing plate, and the pressure-sensitive adhesive layer or the adhesive layer is used to attach the polarizing plate to a device such as a display device, the polarizing plate is the optical film, the polarizing film and the A pressure-sensitive adhesive layer or an adhesive layer may be included in the above order.

In the present application, as the polarizing film, a polarizing film having a light absorption axis formed along one direction in a plane may be used. Such polarizing films are known in various ways. In one example, as the polarizing film, a polyvinyl alcohol (poly(vinyl alcohol), hereinafter PVA)-based polarizing film, which is a typical linear absorption type polarizing film, may be used. Such a polarizing film usually includes a PVA film and an anisotropic absorbing material adsorbed and oriented to the PVA film. As the anisotropic absorbing material, various dichroic pigments may be used, and representatively, an iodine-based material may be used. Such a polarizing film is generally referred to as an iodine-based absorbing linear PVA polarizing film.

For example, the PVA polarizing film can be manufactured through a washing and drying process, after performing each treatment such as swelling, dyeing, crosslinking and stretching to the PVA film. As will be described later, the shrinking force of the polarizing film may be adjusted to a predetermined range, and the shrinking force may be adjusted by controlling a process condition in any one of the above processes. In general, the shrinkage force may be affected by the draw ratio or the like during the drawing process in the above process. That is, when the draw ratio is high, the contraction force increases, and when the draw ratio is low, it may be lowered. However, this method corresponds to one direction in which the shrinking force can be adjusted, and those skilled in the art of manufacturing a polarizing film can easily manufacture a polarizing film having a desired shrinking force according to the purpose.

The polarizing film of the present application, as the iodine-based absorption type linear PVA polarizing film, may include a PVA film and an anisotropic absorbing material adsorbed and oriented on the PVA film.

As the PVA film in the above, for example, a general PVA film conventionally used in a polarizing film may be used. As a material for such a PVA film, PVA or a derivative thereof can be mentioned. PVA derivatives include polyvinyl formal or polyvinyl acetal, and in addition, olefins such as ethylene or propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid or crotonic acid, and alkyl esters or acrylamides thereof The thing modified by etc. is mentioned. The degree of polymerization of PVA is typically about 100 to 10000, and about 1000 to 10000, and the degree of saponification is about 80 to 100 mol%, but is not limited thereto.

As the PVA film, a hydrophilic polymer film such as an ethylene vinyl acetate copolymer-based partial saponification film, a polyene-based oriented film such as a dehydration treatment product of PVA or a dehydrochloric acid treatment product of polyvinyl chloride may also be exemplified.

In the PVA film, an additive such as a plasticizer or a surfactant may be contained. In the above, as the plasticizer, polyol or a condensate thereof may be exemplified, and for example, glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, or polyethylene glycol may be exemplified. When such a plasticizer is used, the proportion is not particularly limited, and may be generally about 20% by weight or less in the PVA film.

The type of the anisotropic absorbing material that may be included in the polarizing film is also not particularly limited. In the present application, among known anisotropic absorbing materials, those capable of satisfying the above-described optical properties may be appropriately selected. As an example of the anisotropic absorbing material, iodine may be exemplified. The ratio of the anisotropically absorbing substance in the polarizing film is not particularly limited as long as it can satisfy desired physical properties.

The polarizing film can be manufactured by performing at least a process of dyeing, crosslinking, and extending|stretching to a PVA film, for example.

In the dyeing process, an anisotropic absorbing material such as iodine may be adsorbed and/or orientated to the PVA film. This dyeing process may be performed together with the stretching process. Dyeing may be generally performed by immersing the film in a solution containing an anisotropically absorbing material, for example, an iodine solution. As the iodine solution As the iodine solution, for example, an aqueous solution containing iodine ions by iodine and an iodide compound serving as a dissolution aid may be used. As the iodide compound, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, or titanium iodide may be used. The concentration of iodine and/or iodide ions in the iodine solution may be controlled within a conventional range depending on the purpose. In the dyeing process, the temperature of the iodine solution is typically 20 to 50° C., 25 to 40° C., and the immersion time is typically 10 to 300 seconds or 20 to 240 seconds, but is not limited thereto.

The crosslinking process performed in the manufacturing process of the polarizing film may be performed using, for example, a crosslinking agent such as a boron compound. The order of the crosslinking process is not particularly limited, and for example, it may be performed together with the dyeing and/or stretching process, or may be performed separately. The crosslinking process can also be performed multiple times. As the boron compound, boric acid or borax may be used. The boron compound may be generally used in the form of an aqueous solution or a mixed solution of water and an organic solvent, and an aqueous boric acid solution is usually used. The boric acid concentration in the boric acid aqueous solution may be selected in an appropriate range in consideration of crosslinking degree and thus heat resistance. An iodide compound such as potassium iodide can also be contained in an aqueous boric acid solution or the like.

The treatment temperature of the crosslinking process is usually in the range of 25°C or higher, 30°C to 85°C or 30°C to 60°C, and the treatment time is usually 5 seconds to 800 seconds or 8 seconds to 500 seconds, but is limited thereto. It is not.

The stretching process is generally performed by uniaxial stretching. Such stretching may be performed together with the dyeing and/or crosslinking process. The stretching method is not particularly limited, and for example, a wet stretching method may be applied. In such a wet stretching method, for example, it is common to perform stretching after dyeing, but stretching may be performed together with crosslinking, and may be performed multiple times or in multiple stages.

An iodide compound such as potassium iodide can be contained in the treatment liquid applied to the wet stretching method. In stretching, the treatment temperature is usually 25°C or higher, 30°C to 85°C, or 50°C to 70°C, and the treatment time is usually 10 seconds to 800 seconds or 30 seconds to 500 seconds, but is not limited thereto. .

In the stretching process, the total draw ratio can be adjusted in consideration of orientation characteristics, etc., and the total draw ratio may be about 3 to 10 times, 4 to 8 times or 5 to 7 times based on the original length of the PVA film. It is not limited thereto. In the above, the total draw ratio may mean a cumulative draw ratio including the draw in each step when the drawing is accompanied by a swelling process other than the drawing process. This total draw ratio may be adjusted to an appropriate range in consideration of orientation, processability of the polarizing film, or possibility of stretching and cutting. As described above, it is possible to control the contraction force through the control of the draw ratio.

In the manufacturing process of the polarizing film, a swelling process may be performed before performing the above process in addition to the dyeing, crosslinking and stretching. By swelling, it is possible to clean the surface of the PVA film with an anti-blocking agent or contamination, and there is also an effect of reducing unevenness such as dyeing deviation.

In the swelling process, water, distilled water, pure water, or the like may be used. The main component of the treatment liquid is water, and if necessary, an additive such as an iodide compound such as potassium iodide or a surfactant, or a small amount of alcohol may be contained.

The treatment temperature in the swelling process is usually about 20°C to 45°C or 20°C to 40°C, but is not limited thereto. Since swelling deviations can cause dyeing deviations, the process parameters can be adjusted so that the occurrence of such swelling deviations is suppressed as much as possible. If necessary, suitable stretching can also be carried out in the swelling process. The draw ratio may be about 6.5 times or less, 1.2 to 6.5 times, 2 to 4 times, or 2 to 3 times based on the original length of the PVA film. The stretching in the swelling process can be controlled so that the stretching in the stretching process performed after the swelling process can be controlled to be small, and the stretching breakage of the film does not occur.

In the manufacturing process of the polarizing film, metal ion treatment may be performed. Such treatment is performed, for example, by immersing the PVA film in an aqueous solution containing a metal salt. Through this, it is possible to contain metal ions in the speculum. In this process, it is possible to adjust the color tone of the PVA polarizing film by adjusting the type or ratio of metal ions. Examples of metal ions that can be applied include metal ions of transition metals such as cobalt, nickel, zinc, chromium, aluminum, copper, manganese, or iron. have.

In the manufacturing process of the polarizing film, a washing process may be performed after dyeing, crosslinking, and stretching. Such a washing process can be performed with a solution of an iodine compound such as potassium iodide, or may be performed using water.

Washing with water and washing with an iodine compound solution may be combined, and a solution containing a liquid alcohol such as methanol, ethanol, isopropyl alcohol, butanol or propanol may also be used.

After passing through such a process, a drying process may be performed to prepare a polarizing film. In the drying process, for example, it may be performed at an appropriate temperature for an appropriate time in consideration of the moisture content required for the polarizing film, and such conditions are not particularly limited.

The thickness of the polarizing film applied in the present application may be in the range of about 5 μm to 25 μm. The thickness may be about 24 μm or less, 23 μm or less, 22 μm or less, 21 μm or less, 20 μm or less, 19 μm or less, 18 μm or less, or 17 μm or less, or about 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, It may be about 10 μm or more, 11 μm or more, 12 μm or more, 13 μm or more, 14 μm or more, 15 μm or more, or 16 μm or more.

The optical film of the present application is disposed on at least one side or both sides of the polarizing film. This optical film may be a protective film for the polarizing film.

In the present application, as the optical film, a polyester film (eg, a PET (poly(ethylene terephthatlate)) film) manufactured by a special stretching process described later is applied. Therefore, the optical film of the present application is a stretched polyester film. The optical film of the present application has a specific non-uniform optical characteristic This optical film of the present application is applied to a polarizing plate even if a high retardation due to high elongation is not applied, so that the so-called rainbow It does not cause optical stains such as stains, etc. In addition, the non-uniform optical properties induce uniform mechanical properties, thereby eliminating the weak properties that appear in the conventional high-stretch polyester film, that is, the conventional high-stretch polyester film. When the film is bent with the orientation main axis as an axis, there is a problem that it is easily broken or cracked, but the optical film of the present application does not have such a problem. It is useful for manufacturing curved devices such as (curved) displays.

The in-plane first direction of the optical film mentioned to describe the optical film below is any one of MD (Machine Direction) and TD (transverse direction) directions when the optical film is a stretched polymer film, and the second direction is It may mean the other direction of MD (Machine Direction) and TD (transverse direction) directions. Accordingly, the first and second directions may be substantially perpendicular to each other. The vertical is a case where the angle formed by the first and second directions is within a range of about 80 degrees to 100 degrees. The angle meaning vertical is about 82 degrees or more, 84 degrees or more, 86 degrees or more, 88 degrees or more, or 90 degrees or more, 98 degrees or less, 96 degrees or less, 94 degrees or less, 92 degrees or less, or 90 degrees in another example. It may be less than or equal to degrees.

In one example, the non-uniform optical properties of the optical film may be defined as optical axes appearing in different directions in each divided region when the optical film is virtually divided into three according to a specific criterion.

For example, in the optical film of the present application, when the optical film is divided into three regions of the same area by a virtual line in a direction horizontal or vertical to the first or second direction in the plane of the optical film, The average optical axis direction of the center area may be different from the average optical axis direction of the left area or the right area. In the above, the optical axis means a slow axis or a fast axis of a corresponding region.

For example, the angle formed by the average optical axis of the center area of the three-divided area and the average optical axis of the left or right area is more than 10 degrees, 10 degrees or more, 11 degrees or more, 12 degrees or more, 13 degrees or more, and 14 degrees. Above, 15 degrees or more, 16 degrees or more, 17 degrees or more, 18 degrees or more, 19 degrees or more, 20 degrees or more, 21 degrees or more, 22 degrees or more, 23 degrees or more, 24 degrees or more, 25 degrees or more, or 50 degrees or less , 49 degrees or less, 48 degrees or less, 47 degrees or less, 46 degrees or less, 45 degrees or less, 44 degrees or less, 43 degrees or less, 42 degrees or less, 41 degrees or less, 40 degrees or less, 39 degrees or less, 38 degrees or less, 37 It may be about degrees or less, 36 degrees or less, 35 degrees or less, 34 degrees or less, 33 degrees or less, 32 degrees or less, 31 degrees or less, 30 degrees or less, 29 degrees or less, 28 degrees or less, 27 degrees or less, or 26 degrees or less.

In addition, in the optical film, left and right regions of the three-divided region may represent similar or symmetrical average optical axes. For example, the angle formed by the average optical axis of the left area and the average optical axis of the right area of the three-divided area is 10 degrees or less, less than 10 degrees, 9 degrees or less, or 9.5 degrees or less, or 0 degrees or more, 1 degree. It may be about 2 degrees or more, 3 degrees or more, 4 degrees or more, 5 degrees or more, 6 degrees or more, 7 degrees or more, or 8 degrees or more.

The above will be described with reference to the drawings.

For example, when the square indicated by the reference numeral 100 in FIG. 1 is referred to as an arbitrary surface of the optical film, an imaginary line perpendicular or horizontal to the first or second direction in the plane of the optical film (dotted line in the drawing, the above-described In the bar and rigidly stretched polymer film, the dotted line may be parallel to the MD direction or the TD direction.), the surface of the optical film is divided into a center area (M), a right area (R), and a left area (L). Can be divided. A typical stretched polymer film exhibits an approximately uniform optical axis determined according to the main stretching direction, but in the present application, different average optical axes are represented in the three-divided regions, which are indicated by both direction arrows within each region in FIG. 1. It is prescribed. As outlined in the figure, the average optical axis tends to have a symmetrical characteristic with large deviations in the center region, the right region, and the center region and the left region, and small deviations in the right and left regions. Surprisingly, this characteristic does not cause optical defects in the polarizing plate even when a high phase difference is not imparted by high stretching. Although the reason is not clear, it is thought that the phenomenon causing optical defects is canceled out or alleviated by the non-uniform property. The non-uniformity of the optical axis may be expressed by the difference between the average optical axis. The average optical axis can be measured by the method described in Examples.

The optical non-uniformity may also be expressed by non-uniformity of the phase difference in the optical film.

For example, in the optical film, the difference (R _in.max -R _{in.min ) between the minimum value (R in.min} ) and the maximum value (R _in.max ) of the in-plane retardation in the optical film is within the range of 200 nm to 1,000 nm. I can. The difference (R _in.max -R _in.min ) is 250 nm or more, 300 nm or more, 350 nm or more, or 400 nm or more, or 950 nm or less, 900 nm or less, 850 nm or less, 800 nm or less, in another example, It may be about 750 nm or less, 700 nm or less, 650 nm or less, 600 nm or less, 550 nm or less, 500 nm or less, or 450 nm or less. That is, a typical stretched polymer film exhibits approximately uniform retardation over the entire surface of the polymer film, but the optical film of the present application exhibits non-uniform retardation characteristics as described above. It is thought that phenomena that cause optical defects such as a rainbow phenomenon are canceled or alleviated by such a non-uniform phase difference characteristic.

In the present specification, the in-plane phase difference is a value usually expressed by the following formula (1).

[Equation 1]

Rin = dХ(nx-ny)

In Equation 1, d is the thickness of the film, nx is the refractive index in the slow axis direction, and ny is the refractive index in the fast axis direction.

In the above, the minimum value (R _in.min ) of the in-plane retardation in the optical film may be in the range of approximately 10 to 300 nm. The minimum value (R _in.min ) is about 20 nm or more, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 65 nm or more, or 70 nm or more, 290 nm or less, 280 nm or less, 270 nm or less, 260 nm or less, 250 nm or less, 240 nm or less, 230 nm or less, 220 nm or less, 210 nm or less, 200 nm or less, 190 nm or less, 180 nm or less, 170 nm or less, 160 nm or less, 150 nm It may be about 140 nm or less, 130 nm or less, 120 nm or less, 110 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, or 75 nm or less.

In the above, the maximum value (R _in.max ) of the in-plane retardation in the optical film may be in the range of 350 to 1,000 nm. In other examples, the maximum value (R _in.max ) is 360 nm or more, 370 nm or more, 380 nm or more, 390 nm or more, 400 nm or more, 410 nm or more, 420 nm or more, 430 nm or more, 440 nm or more, 450 nm or more, 460 nm or more, 470 nm or more, 480 nm or more, 490 nm or more, 990 nm or less, 980 nm or less, 970 nm or less, 960 nm or less, 950 nm or less, 940 nm or less, 930 nm or less, 920 nm Or less, 910 nm or less, 900 nm or less, 890 nm or less, 880 nm or less, 870 nm or less, 860 nm or less, 850 nm or less, 840 nm or less, 830 nm or less, 820 nm or less, 810 nm or less, 800 nm or less, 790 nm or less, 780 nm or less, 770 nm or less, 760 nm or less, 750 nm or less, 740 nm or less, 730 nm or less, 720 nm or less, 710 nm or less, 700 nm or less, 690 nm or less, 680 nm or less, 670 nm Or less, 660 nm or less, 650 nm or less, 640 nm or less, 630 nm or less, 620 nm or less, 610 nm or less, 600 nm or less, 590 nm or less, 580 nm or less, 570 nm or less, 560 nm or less, 550 nm or less, It may be about 540 nm or less, 530 nm or less, 520 nm or less, 510 nm or less, 500 nm or less, or 490 nm or less.

In addition, the average in-plane retardation (R in. _AVG ) of the optical film may be in the range of about 100 to 1,000 nm. The average in-plane retardation (R _in.AVG ) is 150 nm or more, 200 nm or more, or 250 nm or more, or 990 nm or less, 980 nm or less, 970 nm or less, 960 nm or less, 950 nm or less, 940 nm or less in other examples , 930 nm or less, 920 nm or less, 910 nm or less, 900 nm or less, 890 nm or less, 880 nm or less, 870 nm or less, 860 nm or less, 850 nm or less, 840 nm or less, 830 nm or less, 820 nm or less, 810 nm or less, 800 nm or less, 790 nm or less, 780 nm or less, 770 nm or less, 760 nm or less, 750 nm or less, 740 nm or less, 730 nm or less, 720 nm or less, 710 nm or less, 700 nm or less, 690 nm or less , 680 nm or less, 670 nm or less, 660 nm or less, 650 nm or less, 640 nm or less, 630 nm or less, 620 nm or less, 610 nm or less, 600 nm or less, 590 nm or less, 580 nm or less, 570 nm or less, 560 nm or less, 550 nm or less, 540 nm or less, 530 nm or less, 520 nm or less, 510 nm or less, 500 nm or less, 490 nm or less, 480 nm or less, 470 nm or less, 460 nm or less, 450 nm or less, 440 nm or less , 430 nm or less, 420 nm or less, 410 nm or less, 400 nm or less, 390 nm or less, 380 nm or less, 370 nm or less, 360 nm or less, 350 nm or less, 340 nm or less, 330 nm or less, 320 nm or less, 310 It may be about nm or less, 300 nm or less, or 290 nm or less.

In one example, when the protective film surface is divided into three in the same manner as described above, the minimum value (R _in.min ) of the in-plane retardation is confirmed in the center area (region M in FIG. 1), and the maximum value (R _in.max ). May be identified in the left region (region L in FIG. 1) or the right region (region R in FIG. 1).

In one example, the central region (region M of FIG. 1) of the region divided into three may exhibit a lower phase difference than the left and right regions (regions R and L of FIG. 1), and the left and right regions may exhibit a similar in-plane phase difference. .

For example, the difference (RL-M) between the average in-plane phase difference (M) of the center region (M) and the average in-plane phase difference (RL) of the left or right region when divided into three as shown in FIG. 1 is 50 nm. To 1,000 nm. The difference (R _in.max -R _in.min ) is 60 nm or more, 70 nm or more, 80 nm or more, 90 nm or more, 100 nm or more, 110 nm or more, 120 nm or more, 130 nm or more, 140 nm or more, 150 nm or more, 160 nm or more, 170 nm or more, 180 nm or more, 950 nm or less, 900 nm or less, 850 nm or less, 800 nm or less, 750 nm or less, 700 nm or less, 650 nm or less, 600 nm Hereinafter, it may be about 550 nm or less, 500 nm or less, 450 nm or less, 400 nm or less, 350 nm or less, 300 nm or less, 250 nm or less, or 200 nm or less.

In addition, when divided into three as shown in FIG. 1, the absolute value of the difference (R-L) between the average in-plane retardation L of the left area and the average in-plane retardation R of the right area may be about 45 nm or less. The absolute value of the difference is 0 nm or more, 1 nm or more, 2 nm or more, 3 nm or more, 4 nm or more, 5 nm or more, 6 nm or more, 7 nm or more, 8 nm or more, or 9 nm or more, or 40 nm It may be less than or equal to 35 nm, less than 30 nm, less than 25 nm, less than 20 nm, less than 15 nm, or less than 10 nm.

_{In addition, as shown in FIG. 1, the average value M.AVG} ) of the in-plane retardation in the central region among the regions divided into three portions may be in a range of approximately 10 to 290 nm. The minimum value (R _in.min ) is about 20 nm or more, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 65 nm or more, 70 nm or more, 80 nm or more, 90 nm or more, 100 nm or more, 110 nm or more, 120 nm or more, 130 nm or more, 140 nm or more, 150 nm or more, 290 nm or less, 280 nm or less, 270 nm or less, 260 nm or less, 250 nm or less, 240 nm or less, 230 nm It may be 220 nm or less, 210 nm or less, 200 nm or less, 190 nm or less, 180 nm or less, 170 nm or less, or 160 nm or less.

_{In addition, the average value of the in-plane phase difference (RL.AVG} ) in the left or right region among the regions divided into three as shown in FIG. 1 may be in the range of 300 to 1,000 nm. The maximum value (R _in.max ) is 310 nm or more, 315 nm or more, 320 nm or more, 325 nm or more, 330 nm or more, 335 nm or more, or 400 nm or more, 990 nm or less, 980 nm or less, 970 nm or less, 960 nm or less, 950 nm or less, 940 nm or less, 930 nm or less, 920 nm or less, 910 nm or less, 900 nm or less, 890 nm or less, 880 nm or less, 870 nm or less, 860 nm or less, 850 nm Or less, 840 nm or less, 830 nm or less, 820 nm or less, 810 nm or less, 800 nm or less, 790 nm or less, 780 nm or less, 770 nm or less, 760 nm or less, 750 nm or less, 740 nm or less, 730 nm or less, 720 nm or less, 710 nm or less, 700 nm or less, 690 nm or less, 680 nm or less, 670 nm or less, 660 nm or less, 650 nm or less, 640 nm or less, 630 nm or less, 620 nm or less, 610 nm or less, 600 nm Or less, 590 nm or less, 580 nm or less, 570 nm or less, 560 nm or less, 550 nm or less, 540 nm or less, 530 nm or less, 520 nm or less, 510 nm or less, 500 nm or less, 490 nm or less, 480 nm or less, It may be about 470 nm or less, 460 nm or less, 450 nm or less, 440 nm or less, 430 nm or less, 420 nm or less, 410 nm or less, 400 nm or less, 390 nm or less, 380 nm or less, 370 nm or less, or 360 nm or less. .

Targeted physical properties can be effectively achieved by the unique optical properties as described above.

The unique optical properties as described above are obtained by the manufacturing method of the present application, which will be described later.

The manufacturing method of the present application as described above also induces symmetrical properties in terms of mechanical.

For example, in the optical film of the present application, a ratio (S1/S2) of the contraction force S1 in the first direction and the contraction force S2 in the second direction may be in the range of 0.7 to 1.2. The ratio (S1/S2) is 0.75 or more, 0.8 or more, 0.85 or more, 0.9 or more, 0.95 or more, 1 or more, 1.05 or more, 1.1 or more, or 1.15 or more, or 1.15 or less, 1.1 or less, 1.05 or less, 1 or less. , 0.95 or less, 0.9 or less, 0.85 or less, 0.8 or less, or may be about 0.75 or less.

In addition, in the present application, the contraction force (S1 or S2) in the first or second direction may be in the range of 0.5N to 4N. The contraction force (S1 or S2) is, in another example, about 1N or more, about 1.5N or more, about 2N or more, about 2.5N or more, about 3N or more, or about 3.5N or more, about 3.5N or less, about 3N or less, 2.5 It may be about N or less, about 2N or less, about 1.5N or less, or about 1N or less.

In the present specification, the term contractile force is measured by the method presented in Examples to be described later.

Due to the mechanical properties as described above, the optical film of the present application exhibits excellent bending resistance. For example, the optical film exhibits a Mandrel value of 10 pi or less in both the first and second directions. The mandrel value is a value obtained by a mandrel test.

The Mandrel test is a test to check whether the specimen is destroyed when the specimen is bent by inserting it into a cylindrical mandrel, and the mandrel value is an optical film (or a polarizing plate as described later) during the mandrel test. ) Shows no defects such as cracks or cracks.

A specific method of performing the mandrel test is as described in the Examples.

In the case of a high-stretch polyester film, when it is bent in at least one of the MD and TD directions as an axis due to the asymmetry due to high stretching, it is easily cracked or cracked, but the optical film of the present application does not exhibit such characteristics. . In another example, the mandrel value is 9 pie or less, 8 pie or less, 7 pie or less, or 6 pie or less, or 1 pie or more, 2 pie or more, 3 pie or more, 4 pie or more, 5 pie or more, 6 pie or more, or 7 It can be more than a pie.

In another example, the optical film may have 10 fimandrel resistances of 5 or more in both the first and second directions. The mandrel resistance refers to the number of times that defects such as cracks or cracks do not occur when the 10 pie mandrel test is repeated. In another example, the mandrel resistance is 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or 15 or more, or 100 or less. , 95 or less, 90 or less, 85 or less, 80 or less, 75 or less, 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, 45 or less, 40 or less, 35 It may be less than or equal to 30 times, less than 30 times, less than 25 times, or less than 20 times.

In the polarizing plate of the present application, the optical film of the present application is disposed on at least one side or both sides of the polarizing film, for example, as a protective film. Usually, in this arrangement, the MD or TD direction of the optical film is arranged so as to be perpendicular or horizontal to the light absorption axis of the polarizing film. Accordingly, the polarizing plate may reflect the characteristics of the optical film described above as follows.

That is, for example, when the optical film is divided into three regions of the same area with a virtual line in a direction perpendicular or horizontal to the light absorption axis of the polarizing film in the polarizing plate, the average optical axis direction of the central region and the absorption The angle formed by the axis and the average optical axis direction of the left or right area and the angle formed by the absorption axis may be different. In the above, the optical axis means a slow axis or a fast axis of a corresponding region.

For example, an angle formed by the average optical axis of the central region of the three-divided region and the absorption axis may be in a range of about 0° to 29°. In other examples, the angle is greater than 1 degree, 2 degrees or more, 3 degrees or more, 4 degrees or more, 5 degrees or more, 6 degrees or more, 7 degrees or more, 8 degrees or more, 9 degrees or more, 10 degrees or more, 11 degrees or more, 12 degrees or more, 13 degrees or more, 14 degrees or more, 15 degrees or more, 16 degrees or more, 17 degrees or more, 28 degrees or less, 27 degrees or less, 26 degrees or less, 25 degrees or less, 24 degrees or less, 23 degrees or less, 22 It may be less than or equal to 21 degrees, less than or equal to 20 degrees, less than or equal to 19 degrees, or less than or equal to 18 degrees.

In addition, for example, an angle formed by the average optical axis of the left or right area of the three-divided area and the absorption axis may be 30 degrees or more. In other examples, the angle is 31 degrees or more, 32 degrees or more, 33 degrees or more, 34 degrees or more, 35 degrees or more, 36 degrees or more, 37 degrees or more, 38 degrees or more, 39 degrees or more, 40 degrees or more, 41 degrees or more, 42 degrees or more, 43 degrees or more, 90 degrees or less, 89 degrees or less, 88 degrees or less, 87 degrees or less, 86 degrees or less, 85 degrees or less, 84 degrees or less, 83 degrees or less, 82 degrees or less, 81 degrees or less, 80 Degrees or less, 79 degrees or less, 78 degrees or less, 77 degrees or less, 76 degrees or less, 75 degrees or less, 74 degrees or less, 73 degrees or less, 72 degrees or less, 71 degrees or less, 70 degrees or less, 69 degrees or less, 68 degrees or less , 67 degrees or less, 66 degrees or less, 65 degrees or less, 64 degrees or less, 63 degrees or less, 62 degrees or less, 61 degrees or less, 60 degrees or less, 59 degrees or less, 58 degrees or less, 57 degrees or less, 56 degrees or less, 55 Degrees or less, 54 degrees or less, 53 degrees or less, 52 degrees or less, 51 degrees or less, 50 degrees or less, 49 degrees or less, 48 degrees or less, 47 degrees or less, 46 degrees or less, 45 degrees or less, 44 degrees or less, 43 degrees or less , 42 degrees or less, 41 degrees or less, 40 degrees or less, 39 degrees or less, 38 degrees or less, 37 degrees or less, 36 degrees or less, or about 35 degrees or less.

In addition, the angle (A) formed by the average optical axis of the optical film in the central region of the region divided into three in the same manner as in FIG. 1 and the average absorption axis of the polarizing film region overlapping the central region in the polarizing plate, and the left side of the optical film Alternatively, the absolute value of the difference (BA) between the average optical axis of the right area and the average absorption axis of the polarizing film area overlapping with the left or right area (B) is greater than 10 degrees, more than 10 degrees, more than 11 degrees, 12 degrees or more, 13 degrees or more, 14 degrees or more, 15 degrees or more, 16 degrees or more, 17 degrees or more, 18 degrees or more, 19 degrees or more, 20 degrees or more, 21 degrees or more, 22 degrees or more, 23 degrees or more, 24 degrees Or more or 25 degrees or more, 50 degrees or less, 49 degrees or less, 48 degrees or less, 47 degrees or less, 46 degrees or less, 45 degrees or less, 44 degrees or less, 43 degrees or less, 42 degrees or less, 41 degrees or less, 40 degrees or less , 39 degrees or less, 38 degrees or less, 37 degrees or less, 36 degrees or less, 35 degrees or less, 34 degrees or less, 33 degrees or less, 32 degrees or less, 31 degrees or less, 30 degrees or less, 29 degrees or less, 28 degrees or less, 27 It may be less than or equal to 26 degrees, less than 25 degrees, less than 24 degrees, less than 23 degrees, less than 22 degrees, less than 21 degrees, less than 20 degrees, less than 19 degrees, or less than 18 degrees.

In the optical film, since the left and right regions of the three-divided region may represent similar or symmetrical average optical axes, for example, the average optical axis of the left region of the three-divided region and the left region overlap. The absolute value of the difference (DC) between the average value (C) of the angle formed by the absorption axis of the polarizing film region (C) and the average value (D) of the angle formed by the average optical axis of the right region and the absorption axis of the polarizing film region overlapping the right region Silver, 15 degrees or less, 14.5 degrees or less, 14 degrees or less, 13.5 degrees or less, 13 degrees or less, 12.5 degrees or less, 12 degrees or less, 11.5 degrees or less, 11 degrees or less, 10.5 degrees or less, 10 degrees or less, less than 10 degrees, 9 degrees or less or 9.5 degrees or less, or 0 degrees or more, 1 degree or more, 2 degrees or more, 3 degrees or more, 4 degrees or more, 5 degrees or more, 6 degrees or more, 7 degrees or more, 8 degrees or more, or 9 degrees or more It may be about.

In the above, regions of the polarizing film corresponding to the center, left, and right regions divided into three portions of the optical film are in contact with the center, left and right regions, respectively, or overlap with the center, left and right regions of the optical film in a normal direction. Refers to the area observed to be. In addition, the difference between the average optical axis and the absorption axis in the above can be obtained by a method according to an exemplary embodiment described later.

In addition, the polarizing plate also exhibits excellent bending resistance due to the excellent mechanical properties of the optical film described above. For example, the polarizing plate exhibits a Mandrel value of 10 pi or less in both the direction of the light absorption axis and the direction perpendicular thereto. The meaning of the mandrel value is as described in the optical film, and a specific method of performing the mandrel test is as described in Examples. In another example, the mandrel value is 9 pie or less, 8 pie or less, 7 pie or less, or 6 pie or less, or 1 pie or more, 2 pie or more, 3 pie or more, 4 pie or more, 5 pie or more, 6 pie or more, or 7 It can be more than a pie.

In another example, the polarizing plate may have 10 pie mandrel resistances of 5 or more times in both the direction of the light absorption axis and the direction perpendicular thereto. The mandrel resistance refers to the number of times that defects such as cracks or cracks do not occur when the 10 pie mandrel test is repeated. In another example, the mandrel resistance is 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or 15 or more, or 100 or less. , 95 or less, 90 or less, 85 or less, 80 or less, 75 or less, 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, 45 or less, 40 or less, 35 It may be less than or equal to 30 times, less than 30 times, less than 25 times, or less than 20 times.

The polarizing plate of the present application, including the specific optical film as described above, exhibits the above characteristics, and thus, the advantage of the polyester film can be secured with excellent low moisture permeability characteristics, but at the same time, there are no optical defects, and excellent bending resistance can be secured. have.

In one example, the optical film has a moisture permeability of 50 g/m ² ·day or less, 49 g/m ² ·day or less, 48 g/m ² ·day or less, 47 g/m ² ·day or less, 46 g/m ² day or less, 45 g/m ² day or less, 44 g/m ² day or less, 43 g/m ² day or less, 42 g/m ² day or less, 41 g/m ² day or less, 40 g/m ² day or less, 39 g/m ² day or less, 38 g/m ² day or less, 37 g/m ² day or less, 36 g/m ² day or less, 35 g/m ² Day or less, 34 g/m ² day or less, 33 g/m ² day or less, 32 g/m ² day or less, 31 g/m ² day or less or 30 g/m ² day or less, or 0 g/m ² day or more, 5 g/m ² day or more, 10 g/m ² day or more, 15 g/m ² day or more, 20 g/m ² day or more or 25 g/m ² It can be about a day or more. The water vapor transmission rate (WVTR: Water Vapor Transmission Rate) can be measured in a known manner, for example, according to ASTM F1249 standard, the test temperature is 37.6°C, the number of times of the test is 10 times, the test time: 30 minutes (once), the volume flow rate is 9.92. It can be measured under the conditions of SCCM (=cm ³ /min) and a transmission area of 50 cm ^2.

The thickness of the optical film is not particularly limited, and may be selected in an appropriate range in consideration of the secured range such as the aforementioned moisture permeability and the thickness of the optical film of a conventional polarizing plate.

For example, the thickness of the optical film may be in the range of about 20 μm to 250 μm. In another example, the thickness may be about 200 μm or less, 150 μm or less, or 100 μm or less, or about 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, or 70 μm or more.

As the optical film, a polyester film such as a stretched polyester film such as a stretched PET film can be used.

Usually, a stretched PET film is a uniaxial or biaxially stretched film produced by melting/extruding a PET-based resin and stretching it.

PET-based resin usually means a resin in which 80 mol% or more of the repeating unit is made of ethylene terephthalate, and may contain other dicarboxylic acid components and diol components. As other dicarboxylic acid components, for example, isophthalic acid, p-beta-oxyethoxybenzoic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxybenzophenone, bis(4-carboxyphenyl) Ethane, adipic acid, sebacic acid, and/or 1,4-dicarboxycyclohexane, and the like. Examples of other diol components include propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, and bisphenol A. Ethylene oxide adduct, polyethylene glycol, polypropylene glycol, and/or polytetramethylene glycol, and the like, but are not limited thereto.

The dicarboxylic acid component or diol component may be used in combination of two or more as necessary. Moreover, oxycarboxylic acids, such as p-oxybenzoic acid, can also be used together. As another copolymerization component, a dicarboxylic acid component containing a small amount of amide bonds, urethane bonds, ether bonds and carbonate bonds, or a diol component may be used.

As a manufacturing method of PET-based resin, a method of directly polycondensing terephthalic acid, ethylene glycol and/or other dicarboxylic acids or other diols as necessary, dialkyl esters of terephthalic acid and ethylene glycol and/or other dicarboxylic acids as necessary. A method of polycondensing after transesterification of a dialkyl ester of an acid or another diol, and polycondensation of terephthalic acid and/or ethylene glycol ester of another dicarboxylic acid and/or other diol ester as necessary. Method and the like are employed.

For each polymerization reaction, a polymerization catalyst containing an antimony-based, titanium-based, germanium-based or aluminum-based compound, or a polymerization catalyst containing the above-described composite compound may be used.

The polymerization reaction conditions may be appropriately selected depending on the monomers, catalysts, reaction devices and properties of the resin to be used, and are not particularly limited, but, for example, the reaction temperature is usually about 150°C to about 300°C, about 200°C. To about 300°C or about 260°C to about 300°C. In addition, the reaction pressure is usually from atmospheric pressure to about 2.7 Pa, and may be on the reduced pressure side in the second half of the reaction.

The polymerization reaction proceeds by volatilizing a leaving reaction product such as a diol, an alkyl compound, or water.

The polymerization apparatus may be one in which a reaction tank is completed, or a plurality of reaction tanks may be connected. Usually, depending on the degree of polymerization, the reactants are polymerized while being transferred between reaction tanks. In addition, a method of providing a horizontal reaction device in the second half of polymerization and volatilizing while heating/kneading can also be employed.

After polymerization is completed, the resin is discharged from a reaction tank or horizontal reaction device in a molten state, then cooled and pulverized in a cooling drum or a cooling belt, or introduced into an extruder and extruded in a string shape and then cut into pellets. Is obtained. Further, if necessary, solid-phase polymerization may be performed to improve molecular weight or reduce low molecular weight components. As the low molecular weight component that can be included in the PET-based resin, a cyclic trimer component may be mentioned, but the content of the cyclic trimer component in the resin is usually adjusted to 5000 ppm or less or 3000 ppm or less.

The molecular weight of the PET-based resin is usually 0.45 to 1.0 dL/g, 0.50 to when the resin is dissolved in a mixed solvent of phenol/tetrachloroethane = 50/50 (weight ratio) and expressed as an intrinsic viscosity measured at 30°C. 10 dL/g or 0.52 to 0.80 dL/g.

PET-based resins may contain additives as needed. As an additive, a lubricant, an anti-blocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light resistance agent, an impact resistance improving agent, etc. are mentioned, for example. It is preferable that the addition amount thereof is in a range that does not adversely affect the optical properties.

PET-based resins are generally used in the form of pellets assembled by an extruder for compounding of these additives or for forming a film. The size or shape of the pellets is not particularly limited, but is usually a columnar, spherical or flat spherical shape having a height and diameter of 5 mm or less. The PET-based resin thus obtained can be formed into a film shape and subjected to stretching treatment to obtain a transparent and homogeneous PET film with high mechanical strength. Although it does not specifically limit as a manufacturing method thereof, For example, the method described below is adopted.

The dried PET resin pellets are supplied to a melt-extrusion apparatus, and are heated to a melting point or higher to be melted. Next, the molten resin is extruded from a die and rapidly cooled and solidified to a temperature equal to or lower than the glass transition temperature on a rotary cooling drum to obtain an unstretched film in a substantially amorphous state. This melting temperature is determined depending on the melting point of the PET resin to be used or the extruder, and is not particularly limited, but is usually 250°C to 350°C. Further, in order to improve the flatness of the film, it is preferable to increase the adhesion between the film and the rotary cooling drum, and a static application adhesion method or a liquid application adhesion method is preferably employed. In the electrostatic application adhesion method, a linear electrode is usually installed on the upper surface of the film in a direction orthogonal to the flow of the film, and a DC voltage of about 5 to 10 kV is applied to the electrode to provide an electrostatic charge to the film, thereby rotating cooling. It is a method of improving the adhesion between the drum and the film. In addition, the liquid coating adhesion method is a method of improving the adhesion between the rotary cooling drum and the film by uniformly applying a liquid to the whole or part of the surface of the rotary cooling drum (for example, only the portion in contact with both ends of the film). If necessary, both can be used together. PET-based resins to be used may be mixed with two or more types of resins and resins having different structures or compositions as necessary. For example, a granular filler as an anti-blocking agent, a pellet in which an ultraviolet absorber, an antistatic agent, or the like is mixed, and a non-mixed pellet are mixed and used.

The number of laminated films to be extruded may be made into two or more layers as necessary. For example, a pellet containing a granular filler as an anti-blocking agent and a non-blending pellet are prepared and fed from another extruder to the same die to produce a film consisting of two or three layers of ``filler blending/non blending/filler blending”. Extruding, etc. are mentioned.

The unstretched film formed in the above manner is usually stretched at a temperature equal to or higher than the glass transition temperature. The stretching temperature is usually 70°C to 150°C, 80 to 130°C, or 90 to 120°C.

In the present application, an optical film (polyester film) exhibiting the above-described characteristic characteristics may be formed by applying stress in both directions perpendicular to the traveling direction while the film is stretched in the stretching process. This will be described with reference to FIG. 2. In general, the stretching process of the polymer film is a continuous process, whereby the polymer film is stretched while progressing in one direction, and the stretching direction is a direction perpendicular to the progressing direction, a horizontal direction, or an oblique direction.

Referring to FIG. 2, if the direction in which the unstretched film 1000 is stretched in FIG. 2 is the direction of the black dotted arrow, stress is applied in both directions perpendicular to the direction (in the direction of the red arrow in FIG. 2), The characteristic film described above is different in optical properties of the center region and the left and right regions due to the effect of stress acting on both sides perpendicular to the advancing or stretching direction and perpendicular to the advancing direction by making the stretching direction perpendicular or horizontal to the advancing direction. Can be obtained. In addition, according to this method, since the film can be manufactured without performing relatively high stretching in any one direction, as in the conventional high-stretch film, it is possible to obtain a film having excellent properties in terms of the above-described bending properties.

In the above method, a method of applying stress in both directions perpendicular to the advancing direction of the film is not particularly limited. For example, by fixing both side surfaces perpendicular to the moving direction of the film with a fixing means, and adjusting the fixing force by the fixing means, the film can advance and stress is not applied in both directions.

In the above process, the degree of stretching performed vertically or horizontally with the traveling direction is not particularly limited. For example, the stretching may be performed so that the stretching ratio in the stretching direction is about 1.1 to 6 times. In other examples, the draw ratio is 1.2 times or more, 1.3 times or more, 1.4 times or more, 1.5 times or more, 1.6 times or more, 1.7 times or more, 1.8 times or more, 1.9 times or more, 2.0 times or more, 2.1 times or more, 2.2 times or more. , 2.3 times or more, 2.4 times or more, 2.5 times or more, 2.6 times or more, 2.7 times or more, 2.8 times or more, 2.9 times or more, 3.0 times or more, 3.1 times or more, 3.2 times or more, 3.3 times or more, 3.4 times or more, 3.5 More than times, more than 3.6 times, more than 3.7 times, more than 3.8 times, more than 3.9 times, more than 4.0 times, more than 4.1 times, more than 4.2 times, more than 4.3 times, more than 4.4 times, more than 4.5 times, more than 4.6 times, more than 4.7 times , 4.8 times or more, 4.9 times or more, 5.0 times or more, 5.1 times or more, 5.2 times or more, 5.3 times or more, 5.4 times or more, 5.5 times or more, 5.6 times or more, 5.7 times or more, 5.8 times or more, or 5.9 times or more, 5.9 times or less, 5.8 times or less, 5.7 times or less, 5.6 times or less, 5.5 times or less, 5.4 times or less, 5.3 times or less, 5.2 times or less, 5.1 times or less, 5.0 times or less, 4.9 times or less, 4.8 times or less, 4.7 times Below, 4.6 times or less, 4.5 times or less, 4.4 times or less, 4.3 times or less, 4.2 times or less, 4.1 times or less, 4.0 times or less, 3.9 times or less, 3.8 times or less, 3.7 times or less, 3.6 times or less, 3.5 times or less, 3.4 times or less, 3.3 times or less, 3.2 times or less, 3.1 times or less, 3.0 times or less, 2.9 times or less, 2.8 times or less, 2.7 times or less, 2.6 times or less, 2.5 times or less, 2.4 times or less, 2.3 times or less, 2.2 times It may be 2.1 times or less, 2.0 times or less, 1.9 times or less, 1.8 times or less, 1.7 times or less, 1.6 times or less, 1.5 times or less, 1.4 times or less, 1.3 times or less, or 1.2 times or less. When the draw ratio is increased, a relatively high phase difference is exhibited in the central region, and when the draw ratio is lowered, a relatively low phase difference is expressed. Therefore, an appropriate draw ratio can be set in consideration of this.

The draw ratio as described above may be achieved by stretching once, or by performing the stretching process a plurality of times.

In the above process, the degree of stress applied in both directions perpendicular to the traveling direction is not particularly limited. The stress applied in both vertical directions may be higher or lower than the stress applied to the film in the progress direction.

For example, the stress applied to the film in both vertical directions may be within a range of 0.01 to 6 times the stress applied to the film in the traveling direction. In another example, the stress applied to the film in both vertical directions is 0.02 times or more, 0.03 times or more, 0.04 times or more, 0.05 times or more, 0.06 times or more, 0.07 times or more, 0.08 times or more, 0.09 times or more, 0.1 times or more, 0.2 times or more, 0.3 times or more, 0.4 times or more, 0.5 times or more, 0.6 times or more, 0.7 times or more, 0.8 times or more, 0.9 times or more, 1.0 times or more, 1.1 times More than, 1.2 times or more, 1.3 times or more, 1.4 times or more, 1.5 times or more, 1.6 times or more, 1.7 times or more, 1.8 times or more, 1.9 times or more, 2.0 times or more, 2.1 times or more, 2.2 times or more, 2.3 times or more, 2.4 times or more, 2.5 times or more, 2.6 times or more, 2.7 times or more, 2.8 times or more, 2.9 times or more, 3.0 times or more, 3.0 times or more, 3.1 times or more, 3.2 times or more, 3.3 times or more, 3.4 times or more, 3.5 times More than, 3.6 times or more, 3.7 times or more, 3.8 times or more, 3.9 times or more, 4.0 times or more, 4.1 times or more, 4.2 times or more, 4.3 times or more, 4.4 times or more, 4.5 times or more, 4.6 times or more, 4.7 times or more, 4.8 times or more, 4.9 times or more, 5.0 times or more, 5.1 times or more, 5.2 times or more, 5.3 times or more, 5.4 times or more, 5.5 times or more, 5.6 times or more, 5.7 times or more, 5.8 times or more or 5.9 times or more, or 5.9 Times or less, 5.8 times or less, 5.7 times or less, 5.6 times or less, 5.5 times or less, 5.4 times or less, 5.3 times or less, 5.2 times or less, 5.1 times or less, 5.0 times or less, 4.9 times or less, 4.8 times or less, 4.7 times or less , 4.6 times or less, 4.5 times or less, 4.4 times or less, 4.3 times or less, 4.2 times or less, 4.1 times or less, 4.0 times or less, 3.9 times or less, 3.8 times or less, 3.7 times or less, 3.6 times or less, 3.5 times or less, 3.4 Times less, 3.3 times or less, 3.2 times or less, 3.1 times or less, 3.0 times or less, 2.9 times or less, 2.8 times or less, 2.7 times or less, 2.6 times or less, 2.5 times or less, 2.4 times or less, 2.3 times or less, 2.2 times or less, 2.1 times or less, 2.0 times or less, 1.9 times or less, 1.8 times or less, 1.7 times or less, 1.6 times or less, 1.5 times or less, 1.4 times or less, 1.3 times or less, 1.2 times Below, 1.1 times or less, 1.0 times or less, 0.9 times or less, 0.8 times or less, 0.7 times or less, 0.6 times or less, 0.5 times or less, 0.4 times or less, 0.3 times or less, 0.2 times or less, 0.1 times or less, 0.09 times or less, It may be 0.08 times or less, 0.07 times or less, 0.06 times or less, 0.05 times or less, 0.04 times or less, 0.03 times or less, or 0.02 times or less. The stress can be adjusted, for example, using a fixing means as described above.

Heat treatment can be performed on the stretched film obtained as described above. In addition, relaxation treatment may be performed as necessary. The heat treatment temperature is usually 150°C to 250°C, 180 to 245°C or 200°C to 230°C. In addition, the heat treatment time is usually 1 to 600 seconds or 1 to 300 seconds or 1 to 60 seconds.

The temperature of the relaxation treatment is usually 90 to 200°C or 120 to 180°C. In addition, the amount of relaxation is usually 0.1 to 20% or 2 to 5%. The temperature and the amount of relaxation of the relaxation treatment can be set so that the thermal contraction rate at 150°C of the PET film after the relaxation treatment is 2% or less, and the temperature at the time of the relaxation treatment.

Optionally, if necessary, after the stretching treatment, additional stretching may be performed in a direction perpendicular to the main stretching direction. In this process, stress may or may not be applied to both sides in the traveling direction. This stretching temperature is usually 70°C to 150°C, 80°C to 130°C, or 90°C to 120°C. In addition, the draw ratio can be adjusted within the range mentioned at the time of the first drawing. After that, heat treatment and relaxation treatment can be performed as necessary. The heat treatment temperature is usually 150°C to 250°C or 180°C to 245°C or 200 to 230°C. The heat treatment time is usually 1 to 600 seconds, 1 to 300 seconds, or 1 to 60 seconds.

The temperature of the relaxation treatment is usually 100 to 230°C, 110 to 210°C, or 120 to 180°C. In addition, the amount of relaxation is usually 01 to 20%, 1 to 10%, or 2 to 5%. The temperature and the amount of relaxation of the relaxation treatment can be set so that the thermal contraction rate at 150°C of the PET film after the relaxation treatment is 2% or less, and the amount of relaxation and the temperature during the relaxation treatment.

Subsequent to the above-described stretching process, a known additional heat treatment or the like may be performed.

In the optical film applied in the present application, a known functional layer such as an anti-glare layer, a conductive layer, a hard coating layer, a smoothing layer, an anti-blocking layer, a primer layer and/or an anti-reflection layer may be present.

The polarizing plate of the present application may include a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer may be present to attach the polarizing plate to a display device such as an LCD or OLED. In this case, as described above, the optical film, the polarizing film, and the pressure-sensitive adhesive layer of the present application may be included in the polarizing plate in the above order. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited, and for example, an acrylic polymer, a silicone polymer, polyester, polyurethane, polyamide, polyether, or a polymer such as fluorine-based or rubber-based polymer is appropriately selected and used as a base polymer. I can. As described above, a release film may be temporarily attached and covered for the purpose of preventing contamination of the exposed surface of the penis pressure-sensitive adhesive layer until it is provided for practical use.

The thickness of the pressure-sensitive adhesive layer may be in the range of 5 μm to 100 μm. In another example, the thickness may be about 10 μm or more, 15 μm or more, or 20 μm or more, or about 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, or 30 μm or less.

In addition to the above-described elements, the polarizing plate of the present application may include other necessary components.

For example, the polarizing plate may further include an adhesive layer between the optical film and the polarizing film. Such an adhesive layer may be used for attaching the optical film to the polarizing film.

As the adhesive, for example, an adhesive layer used for attaching a polarizing film and an optical film in a conventional polarizing plate can be used.

The adhesive layer is, for example, a polyvinyl alcohol-based adhesive; Acrylic adhesives; Vinyl acetate-based adhesives; Urethane adhesive; Polyester adhesive; Polyolefin adhesive; Polyvinyl alkyl ether adhesives; Rubber-based adhesives; Vinyl chloride-vinyl acetate-based adhesives; Styrene-butadiene-styrene (SBS) adhesive; Styrene-butadiene-styrene hydrogenated product (SEBS) adhesive; Ethylene-based adhesives; And one or more types of acrylic acid ester-based adhesives. Such an adhesive may be formed using, for example, a water-based, solvent-based, or non-solvent-based adhesive composition. In addition, the adhesive composition may be a thermosetting type, room temperature curing type, moisture curing type, active energy ray curing type, or a hybrid curing type adhesive composition.

The method of forming the adhesive layer on the polarizing film is not particularly limited, and for example, a method of applying and curing the adhesive composition to a polarizing film, a droplet method, or the like may be used.

The thickness of the adhesive layer may be, for example, in the range of about 1 μm to 5 μm or about 2 μm to 4 μm.

As an additional configuration, the polarizing plate may further include a cured resin layer or an optical film between the polarizing film and the pressure-sensitive adhesive layer. In the above, the cured resin layer is commonly referred to as a hard coating layer, and is generally applied instead of omitting any one of the optical films from the polarizing plate. The type of the cured resin layer that can be applied in the present application is not particularly limited, and various types of cured resin layers used to provide the thin polarizing plate may be applied. Usually, such a cured resin layer may include an epoxy resin, an oxetane resin, a urethane resin and/or an acrylic resin, and such a resin layer is known in various ways. The thickness of the cured resin layer may be, for example, in the range of about 4 μm to 10 μm or about 4.5 μm to 10 μm.

When an optical film exists between the polarizing film and the pressure-sensitive adhesive layer, a known optical film may be used as the optical film. Usually, a thermoplastic resin film excellent in transparency, mechanical strength, thermal stability, moisture barrier property or isotropic property is used. Examples of such resins include cellulose resins such as TAC (triacetyl cellulose), polyester resins such as PET (poly(ethylene terephthalate)), polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins. , A polyolefin resin, a (meth)acrylic resin, a cyclic polyolefin resin such as a norbornene resin, a polyarylate resin, a polystyrene resin, a polyvinyl alcohol resin, or a mixture thereof. The thickness of the optical film may be within the thickness range of the aforementioned optical film.

An appropriate configuration may exist among the cured resin layer or optical film between the polarizing film and the pressure-sensitive adhesive layer, but it is advantageous to have the cured resin layer present in terms of securing desired shrinking force properties. In other words, since the cured resin layer is usually a thin layer formed by curing the resin, physical properties such as shrinking force and tensile properties are insignificant compared to the optical film, and the degree of affecting the overall characteristics of the polarizing plate is small. It does not have a significant influence on the shrinkage force properties formed by the relationship between the film and the polarizing film.

The polarizing plate of the present application may further include one or more functional layers selected from the group consisting of other known configurations, for example, an antireflection layer, an antiglare layer, a retardation plate, a wide viewing angle compensation film, and/or a brightness enhancement film. have.

The present application also relates to a display device, for example an LCD or OLED. The display device such as the LCD or OLED may include the polarizing plate of the present application. The display device may include, for example, a display panel such as an LCD panel or an OLED panel, and the polarizing plate of the present application attached to the display panel.

The type of the display panel that can be applied to the display device of the present application, the position of the polarizing plate attached to the panel, and the like are not particularly limited. That is, as long as the polarizing plate of the present application is applied, the display panel may be implemented in various known manners.

Typically, a display device such as an OLED includes one polarizing plate for antireflection, and the like, and a display device such as an LCD includes two polarizing plates on both sides of a display panel (liquid crystal panel). When two polarizing plates are included as described above, the above-described polarizing plate may be included in the display device as at least one of the two polarizing plates, and in some cases, both of the polarizing plates of the present application may be applied.

For example, in an example of the present application, the display device includes the display panel (eg, a liquid crystal panel) and first and second polarizing plates attached to both surfaces of the display panel, and the first and Any one or both of the second polarizing plates may be the polarizing plates of the present application.

In one example, the first polarizing plate is a viewing-side polarizing plate, and may be a polarizing plate closer to an observer who observes the display screen among the first and second polarizing plates. For example, when the display device is an LCD device, among the first and second polarizing plates, the first polarizing plate is a polarizing plate disposed farther from the backlight than the second polarizing plate, and the second polarizing plate is a polarizing plate disposed closer to the backlight. Can be

In this case, the polarizing plate of the present application may be applied as at least the first polarizing plate, that is, the viewing-side polarizing plate. In this case, the second polarizing plate, that is, a polarizing plate disposed closer to the backlight may also be the polarizing plate of the present application or another polarizing plate. There is no particular limitation on the type of polarizing plate applied when another polarizing plate is applied, and a known polarizing plate may be applied.

For example, a polarizing film as the other polarizing plate; A polarizing plate including a protective film formed on one surface of the polarizing film and a pressure-sensitive adhesive layer formed on the other surface of the polarizing film and attaching the polarizing plate to the display panel may be used. A protective film or a protective layer (the above-described cured resin layer) may also exist between the polarizing film of the polarizing plate and the pressure-sensitive adhesive layer.

In the above structure, a known protective film may be applied as the protective film of the second polarizing plate. For example, the above-described high-stretch protective film (eg, high-stretch polyester film) may be applied as the protective film.

Such highly elongated polyester films usually exhibit very high in-plane retardation. Therefore, when the high-stretch polyester film is applied, the second polarizing plate has an in-plane retardation (based on a 550 nm wavelength) of 2,000 nm or more, 2,000 nm to 3,000 nm, or more than 2,000 nm to 3,000 nm or less. It may include a film.

The display device may be an LCD device, and in this case, the display panel may be a liquid crystal panel.

The first and second polarizing plates may be disposed so that their light absorption axes are perpendicular to each other on both sides of the display panel.

In this case, the first and second polarizing plates each have a smaller angle between the polarizing film or the one side of the polarizing plate and the light absorption axis of the polarizing film in the range of 0 degrees to 10 degrees or in the range of 80 degrees to 100 degrees. There may be a polarizing plate in which a smaller angle of the polarizing film or an angle formed by a side of the polarizing plate and the light absorption axis of the polarizing film is in the range of 35° to 55° or in the range of 125° to 145°.

The present application may provide a polarizing plate including a polyester film that can utilize excellent low moisture permeability without occurrence of optical defects, and does not easily crack or crack even when bending or the like occurs, and a display device to which the same is applied.

1 is a diagram illustrating a method of dividing an optical film or a polarizing plate into three portions.
2 is a diagram illustrating a process of manufacturing the optical film of the present application by way of example.
3 is a diagram showing points in which an optical axis, an absorption axis, and a phase difference are evaluated in Example.
4 is a photograph showing a process of evaluating mandrel characteristics.

Hereinafter, the present application will be specifically described through Examples and Comparative Examples, but the scope of the present application is not limited by the following Examples.

The term MD referred to in the present specification refers to the machine direction of the stretched film unless otherwise specified, and TD refers to the transverse direction of the stretched film unless otherwise specified.

Preparation Example 1. Preparation of PVA polarizing film

After swelling a PVA (poly(vinyl alcohol)) film (Japan Synthetic Company, polymerization degree of about 3,000) having a thickness of about 45 μm in a pure solution at a temperature in the range of about 20° C. to 30° C., from 30° C. to The dyeing process was performed for about 10 to 30 seconds in an iodine solution at a temperature of about 40°C. After that, after performing the cleaning process for about 20 seconds with a boric acid solution (concentration: about 2% by weight) at a temperature of about 40°C, it is stretched about 6 times in a boric acid solution of 50°C to 60°C and about 4.0% by weight. Then, after stretching, a complementary color process was performed in a KI solution having a concentration of about 2 to 4% by weight, and dried to prepare a polarizing film having a thickness of about 17 μm.

Preparation Example 2. Preparation of optical film

Polyester (A) production

The esterification reactor was heated to 200°C, 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were added, and 0.017 parts by mass of antimony trioxide, 0.064 parts by mass of magnesium acetate tetrahydrate and 0.16 parts by mass of triethylamine were added as a catalyst while stirring. The esterification reaction under pressure was carried out under the conditions of a gauge pressure of 0.34 MPa and a temperature of 240° C. through pressurized heating, and the reactor was turned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. The temperature was raised to 260°C over 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added. After 15 minutes, the mixture was dispersed with a high-pressure disperser, and the esterification reaction product was transferred to a polycondensation reactor, and a polycondensation reaction was carried out under reduced pressure at 280°C. After completion of the reaction, it was subjected to filtration, extruded from a nozzle into a strand shape, cooled/solidified, and produced into a pellet shape to obtain a polyester (A) pellet.

Preparation of polyester (B)

10 parts by mass of an ultraviolet absorber (2,2'-(1,4-phenylene) bis(4H-3,1-benzoxyzinon-4-one) and 90 parts by mass of the polyester (A) are mixed, and a kneading extruder A polyester (B) containing an ultraviolet absorber was obtained.

Manufacture of optical film

Polyester (A) pellets and polyester (B) pellets were mixed at a mass ratio of 90:10 (A:B), dried under reduced pressure at 135°C for 6 hours (1 Torr), and then fed to extruder 2 (for intermediate layer II layer) I did. Further, polyester (A) pellets were dried, fed to extruder 1 (for outer layer I layer and outer layer III), respectively, and dissolved at 285°C. Through the extrusion process using the extruders 1 and 2, an unstretched film having a three-layer structure having a thickness ratio of 10:80:10 of the I layer, the II layer, and the III layer was obtained.

While the unstretched film was advanced (in the direction of the black arrow in Fig. 2) in a stretching machine, it was stretched approximately 1.8 times in parallel with the progressing direction. During the stretching process, stress (approximately 0.8 to 1.5 times the stress applied in the traveling direction) was applied by fixing both ends of the unstretched film perpendicular to the traveling direction with a fixing means. Subsequently, the stretched film was subjected to heat treatment and relaxation treatment to obtain an optical film having a thickness of about 80 μm.

Example 1.

The polarizing plate was produced in the following manner. First, the optical film of Preparation Example 2 was attached to one side of the PVA polarizing film prepared in Preparation Example 1 using an epoxy-based ultraviolet curable adhesive (thickness: 2 μm to 3 μm). At the time of attachment, the stretching direction of the optical film and the absorption axis direction of the PVA polarizing film were substantially perpendicular to each other. Subsequently, an epoxy-based hard coating layer was formed to a thickness of about 5 to 7 μm on the surface of the PVA polarizing film to which the optical film was not attached. Thereafter, an acrylic pressure-sensitive adhesive layer having a thickness of about 25 μm was formed under the hard coating layer to prepare a polarizing plate. The polarizing plate has a square shape, and the angle formed by the long side of the rectangular polarizing plate and the light absorption axis of the polarizing film was cut to be approximately 0 degrees or 90 degrees.

In the polarizing plate prepared as described above, the relationship and retardation between the absorption axis of the polarizing film and the fast axis of the optical film were measured using an AxoScan measuring device for the polarizing plate.

As shown in Fig. 3, the axis relationship and phase difference are measured with a force of 100 mm along the width direction (TD direction, dotted arrow direction in Fig. 3) of the polarizing plate with an end of one side as a reference (0 mm) on the surface of the polarizing plate. I did. In the above, the absorption axis of the polarizing film and the fast axis of the optical film were measured at an angle formed by the axis with respect to the MD direction of the polarizing film (a direction perpendicular to the TD direction in FIG. 3).

The polarizer was placed in the measurement position, and the AxoScan measurement equipment and computer were operated. When the AxoScan engine is running and the green light is on, it waited for more than 20 minutes after running AxoView. The number of Measurement to Average was changed from 1 to 80, and the above was evaluated by performing calibration (Optical Wavelength 550 nm Air condition, after Run Once, Calibrate → Standard sample, and then Run Once, Ret Zero). In the measurement process, click Tip-Tilt Measurement, select Arbitary field-of-view, set Number of Rotations to 4 ~ 6, keep the remaining conditions as it is, and click Accept to proceed with the measurement.

To obtain results through MLSP use, run Axometrics Multi-Layer Analysis, enter information such as nx, ny, nz and thickness of the film through Edit Layer, and load AxoScan measurement information (Select all Import data). ), You can also output data by opimizing after aligning.

Table 1 summarizes the measurement results.

Position(mm) Absorption axis angle (degrees) Fast axis angle (degrees) Phase difference (nm) 0 0.23 33.22 457 100 0.15 33.66 472 200 0.23 39.93 387 300 0.05 41.39 357 400 0.03 36.07 322 500 0.06 34.36 225 600 0.12 18.81 319 700 0.03 42.11 270 800 0.22 43.85 125 900 0.17 2.92 117 1000 0.15 15.21 71 1100 0.02 4.02 150 1200 0.02 9.56 180 1300 0.02 8.05 270 1400 0.04 39.73 200 1500 -0.11 40.83 110 1600 0.26 35.72 247 1700 0.12 42.92 299 1800 0.09 47.21 337 1900 0.15 49.51 388 2000 0.11 38.24 411 2100 0.15 44.28 454 2200 0.17 46.24 489 Position (mm): Distance from the reference position (0mm in Fig. 3) to the measurement position measured in the TD direction
Absorption axis angle (degrees): The angle formed by the absorption axis of the polarizing film and the polarizing plate MD direction (the direction perpendicular to the TD in FIG. 3) (unit: degrees)
Fast axis angle (degrees): The angle formed by the fast axis of the optical film and the polarizing plate MD direction (the direction perpendicular to the TD in FIG. 3) (unit: degrees)
Retardation: In-plane retardation of the optical film (unit: nm)

The polarizing plate of Example 1 was attached to the LCD panel as a viewing-side polarizing plate, and whether optical defects such as rainbow stains were recognized with the naked eye were observed from the front and inclined directions. Optical defects such as the rainbow stain were not recognized in the LCD panel on which the polarizing plate was mounted toward the viewer.

Mandrel properties were evaluated for the polarizing plate. Evaluation was performed using a general Cylindrical Mandrel Bending Tester, and FIG. 4 is a photograph of a process in which such evaluation is performed. The condition of the test rod was 20 pi at 6 wave, and evaluation was performed while replacing the rod at 2 pi intervals. A sample was prepared by cutting the polarizing plate to be 300 mm and 30 mm in width and length, and evaluation was performed. A sample having a length of 300 mm in the direction of the absorption axis of the polarizing film and a sample having a length of 300 m in the direction perpendicular to the absorption axis were prepared and applied for evaluation. The application rod was fixed to the instrument after setting, and one end of the sample was fixed to the Grap Jig of the tester. At this time, the surface of the optical film was made to be outside (that is, the polarizing film was placed on the device side rather than the optical film). As shown in Fig. 4, after bending the sample at an angle of 90 degrees for 2 seconds, it was placed again, and the sample was separated from the device. The presence or absence of cracks was evaluated by the transmission inspection of the three-wavelength lamp light. A case in which a crack having a size of more than 15 mm occurred was evaluated as cracking.

As a result of the evaluation, when the polarizing plate was bent in a direction parallel to the light absorption axis, no crack occurred up to a rod of 8 pi, and when the polarizing plate was bent in a direction perpendicular to the light absorption axis, no crack occurred up to a rod of 6 pi.

In addition, in the case of repeatedly performing the bending test by applying a 10-pi rod, cracks did not occur up to 14 times when bending in a direction parallel to the light absorption axis, and 15 when bending in a direction perpendicular to the light absorption axis. Crack did not occur until the time.

Claims (11)

A polarizing film having a light absorption axis formed in one direction; And an optical film formed on at least one surface of the polarizing film,
When the optical film is divided into three portions by a virtual line in a direction horizontal or vertical to the light absorption axis, the angle formed by the average optical axis of the central region of the optical film and the light absorption axis is in the range of 0 degrees to 29 degrees. , A polarizing plate having an angle formed by the average optical axis of the left or right area and the light absorption axis of 30 degrees or more. The method of claim 1, wherein the angle (A) formed by the average optical axis of the central region of the optical film and the average light absorption axis of the polarizing film region overlapping the central region, and the average optical axis of the left or right region of the optical film and the left Or a polarizing plate in which the absolute value of the difference (BA) of the angle (B) formed by the average light absorption axis of the polarizing film region overlapping with the right region is more than 10 degrees. The method of claim 1, wherein the average optical axis of the left area of the optical film is divided into three sections and the absorption axis of the polarizing film overlapping the left area, and the average optical axis of the right area of the optical film. The absolute value of the difference (DC) between the average value (D) of the angle formed by the absorption axis of the polarizing film region overlapping the right region is 15 degrees or less. The polarizing plate of claim 1, wherein the average in-plane retardation (based on a 550 nm wavelength) of the optical film is in a range of 100 to 1,000 nm. The polarizing plate according to claim 1, wherein the optical film has a moisture permeability of 50 g/m ² ·day or less. The polarizing plate according to claim 1, wherein the optical film is a polyester film. The polarizing plate according to claim 1, wherein the polarizing film is a polyvinyl alcohol polarizing film. The polarizing plate according to claim 1, further comprising an adhesive layer, wherein an optical film, a polarizing film, and an adhesive layer are arranged in the above order. Liquid crystal panel; A display device comprising first and second polarizing plates stacked on both surfaces of the liquid crystal panel, and at least one of the first and second polarizing plates is the polarizing plate of claim 1. The display device according to claim 9, wherein the first polarizing plate is a viewer-side polarizing plate, and the first polarizing plate is the polarizing plate of claim 1. The method according to claim 10, wherein the second polarizing plate comprises: a polarizing film; A protective film formed on one surface of the polarizing film and a pressure-sensitive adhesive layer formed on the other surface of the polarizing film to attach the second polarizing plate to the liquid crystal panel, and the protective film has an in-plane retardation of 2,000 nm for a wavelength of 550 nm. A display device that is greater than or equal to nm.

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