KR20210041851A - Curved Display Device - Google Patents

Abstract

The present application relates to a curved display device and a manufacturing method thereof. According to the present application, it is possible to provide the curved display device which can be manufactured through a simple and economical process and in which a designed curved shape is stably maintained, and the manufacturing method thereof. The curved display device includes: a display panel, and a polarizing plate attached to one surface of the display panel, wherein the polarizing plate has a ratio (SP/SV) of a contraction force (SP) in a direction of the light absorption axis to a contraction force (SV) in a direction perpendicular to the direction of the light absorption axis, and the ratio is less than 0.9 or greater than 1.5.

Description

Curved Display Device {Curved Display Device}

The present application relates to a curved display device and a manufacturing method thereof.

Various display devices including LCD (Liquid Crystal Display) devices, PDP (Plasma Display Panel) devices, or OLED (Organic Light Emitting Diode) devices are known, and such display devices are used in portable devices such as mobile phones and multimedia devices. It is applied to a variety of applications ranging from notebook computers or computer monitors to large or small televisions.

Most of these display devices are flat panel display devices, but in recent years, curved display devices are also being developed in consideration of design aspects and degree of immersion during image observation.

Such curved display devices are manufactured in various ways, but methods known to date are processes that require complicated manufacturing processes or high cost.

In addition, the curved display device manufactured in a manner known to date also has a problem in that the curved shape of the once manufactured display device is not stably maintained.

An object of the present application is to provide a curved display device and a method of manufacturing the same, which can be manufactured through a simple and economical process, and stably maintains a designed curved shape.

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.

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 above °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 20 RH%, for example, about 18 RH. % Or less, 15RH% or less, or about 10RH% or less, or about 1 RH% or more, or about 2RH% or more, measured at a relative humidity. 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.

The curved display device of the present application includes a display panel and a polarizing plate attached to at least one surface of the panel.

The curved display device referred to herein refers to a display device having a curvature measured on at least one main surface of more than zero. In the above, the main surface of the display device refers to a surface on which an image is emitted from the display device or a surface on the opposite side thereof. In other examples, the curvature of the main surface of the curved display device is 10R or more, 50R or more, 100R or more, 150R or more, 200R or more, 250R or more, 300R or more, 350R or more, 400R or more, 450R or more, 500R or more, 550R or more. , 600R or more, 650R or more, 700R or more, 750R or more, 800R or more, 850R or more, 900R or more, 950R or more, 1000R or more, 1050R or more, 1100R or more, 1150R or more, 1200R or more, 1250R or more, 1300R or more, 1350R or more, 1400R More than, 1450R or more, 1500R or more, 3000R or less, 2950R or less, 2900R or less, 2850R or less, 2800R or less, 2750R or less, 2700R or less, 2650R or less, 2600R or less, 2550R or less, 2500R or less, 2450R or less, 2400R or less, 2350R or less , 2300R or less, 2250R or less, 2200R or less, 2150R or less, 2100R or less, 2050R or less, 2000R or less, 1950R or less, or 1900R or less. In the above, R means the curved hardness of a circle with a radius of 1 mm. Thus, in the above, for example, 10R is the degree of curvature of a circle with a radius of 10 mm or the radius of curvature for such a circle. In the flat case, the curvature is zero.

In the present specification, the curvature can be measured in a manner known in the industry, for example, non-contact equipment such as 2D Profile Laser Sensor (laser sensor), Chromatic confocal line sensor (confocal sensor), or 3D Measuring Conforcal Microscopy. It can be measured using. Methods of measuring curvature or radius of curvature using such equipment are known.

In the present application, a polarizing plate having an asymmetric contraction force is applied as the polarizing plate. By designing in consideration of the desired curved shape asymmetry of the shrinking force of the polarizing plate, the polarizing plate may play a role of stably maintaining the curved shape of the display device. Accordingly, a curved display device in which the curved shape designed by the polarizing plate is stably maintained during use may be provided. In addition, the asymmetry of the shrinking force of the polarizing plate makes it possible to achieve a desired curved shape with only a simple heat treatment process in the manufacturing process of the display device.

The term shrinkage force referred to in the present specification is a shrinkage force that is determined when a specimen (polarizing plate, etc.) to be measured is held at 70° C. for 2 hours, and specifically, is a physical quantity obtained by measuring in the manner described in the Examples of the present specification.

In the present specification, the polarizing plate having the asymmetry of the contraction force may be simply referred to as an asymmetric polarizing plate.

The specific type of the display panel included in the curved display device of the present application is not particularly limited. As a display panel, a liquid crystal display (LCD) panel, a plasma display panel (PDP) panel, an organic light emitting diode (OLED) panel, and the like are known, and all of the above panels can be applied in the present application. Typically, a display panel that is widely applied is an LCD panel or an OLED panel. In the case of an LCD panel, polarizing plates are attached to both sides of the panel as first and second polarizing plates to control the transmittance of light, and in the case of an OLED panel, a polarizing plate is usually applied to one side of the panel to secure anti-reflection properties. Therefore, in the case of an OLED panel, the aforementioned asymmetric polarizing plate may be applied as a polarizing plate applied to prevent the reflection. In the case of an LCD panel, the asymmetric polarizing plate may be applied as at least one of the first and second polarizing plates disposed on both sides of the panel. In the LCD panel, one polarizing plate other than the asymmetric polarizing plate may be the same as an asymmetric polarizing plate, or a symmetric polarizing plate to be described later.

The asymmetric or symmetric polarizing plate may be a so-called absorption type polarizing plate.

In the case of an absorption type polarizing plate, the polarizing plate generally has a light absorption axis formed in at least one direction, and has a light transmission axis formed in a direction substantially perpendicular to the light absorption axis. In the present specification, the asymmetry of the contraction force of the asymmetric polarizing plate is the contraction force (S _P ) in the light absorption axis direction of the polarizing plate and the contraction force in a direction perpendicular to the light absorption axis direction (that is, the contraction force in a direction perpendicular to the light transmission axis direction ) (S _V ) of the ratio (S _P /S _V ) is less than 0.9 or more than 1.5 means. In this specification, such a polarizing plate may be referred to as an asymmetric polarizing plate. In the present specification, the contraction force in the direction of the light absorption axis means a contraction force in a direction parallel to the direction in which the light absorption axis of the polarizer is formed.

_{The ratio (S P} /S _V ) of the contraction force of the asymmetric polarizing plate may be about 0.85 or less, about 0.8 or less, about 0.75 or less, about 0.7 or less, or about 0.65 or less in another example. In this case, the ratio (S _P /S _V ) of the contraction force may be 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, 0.4 or more, 0.45 or more, 0.5 or more, 0.55 or more, or 0.6 or more. .

_{The ratio (S P} / S _V ) of the contraction force of the asymmetric polarizing plate is, in another example, about 1.6 or more, about 1.7 or more, about 1.8 or more, about 1.9 or more, about 2 or more, about 2.1 or more, about 2.2 or more, about 2.3 Or more, about 2.4 or more, about 2.5 or more, about 2.6 or more, about 2.7 or more, about 2.8 or more, or about 2.9 or more, or about 10 or less, about 9 or less, about 8 or less, about 7 or less, about 6 or less, about 5 or less , It may be about 4 or less or about 3.5 or less.

The contraction force of the asymmetric polarizing plate in the direction of the light absorption axis may be in the range of 6.5N to 15N. The contraction force is, in other examples, about 6.6N or more, 6.7N or more, 6.8N or more, 6.9N or more, 7N or more, 7.1N or more, 7.2N or more, 7.3N or more, 7.4N or more, 7.5N or more, 7.6N or more Or 7.7 N or more, 14.9N or less, 14.8N or less, 14.7N or less, 14.6N or less, 14.5N or less, 14.4N or less, 14.3N or less, 14.2N or less, 14.1N or less, 14N or less, 13.9N or less, 13.8 N or less, 13.7N or less, 13.6N or less, 13.5N or less, 13.4N or less, 13.3N or less, 13.2N or less, 13.1N or less, 13N or less, 12.9N or less, 12.8N or less, 12.7N or less, 12.6N or less, 12.5N or less, 12.4N or less, 12.3N or less, 12.2N or less, 12.1N or less, 12N or less, 11.9N or less, 11.8N or less, 11.7N or less, 11.6N or less, 11.5N or less, 11.4N or less, 11.3N or less , 11.2N or less, 11.1N or less, 11N or less, 10.9N or less, 10.8N or less, 10.7N or less, 10.6N or less, 10.5N or less, 10.4N or less, 10.3N or less, 10.2N or less, 10.1N or less, 10N or less , 9.9N or less, 9.8N or less, 9.7N or less, 9.6N or less, 9.5N or less, 9.4N or less, 9.3N or less, 9.2N or less, 9.1N or less, 9N or less, 8.9N or less, 8.8N or less, 8.7N It may be 8.6N or less, 8.5N or less, 8.4N or less, 8.3N or less, 8.2N or less, or 8.1N or less. By adjusting the contraction force in the direction of the light absorption axis as described above, a desired curved display device can be manufactured and the curved shape can be efficiently maintained.

The range of the contraction force in a direction perpendicular to the direction of the light absorption axis of the asymmetric polarizing plate is not particularly limited, and may be adjusted within a range capable of satisfying the _{above-described ratio (S P} /S _{V ).}

On the other hand, among the polarizing plates mentioned in the present application, the symmetric polarizing plate, that is, the polarizing plate having the symmetry of the contraction force, is the contraction force (S _P ) of the entire polarizing plate in the direction of the light absorption axis and the contraction force of the entire polarizing plate in a direction perpendicular to the direction of the light absorption axis. The ratio of (S _{V ) (S P} /S _V ) refers to a polarizing plate in the range of 0.9 to 1.5. In other examples, the ratio (S _P /S _V ) in the symmetric polarizing plate is about 0.91 or more, about 0.92 or more, about 0.93 or more, about 0.94 or more, about 0.95 or more, about 0.96 or more, or about 0.97 or more, about 1.49 or less, about 1.48 or less, about 1.47 or less, about 1.46 or less, about 1.45 or less, about 1.44 or less, about 1.43 or less, about 1.42 or less, about 1.41 or less, about 1.4 or less, about 1.39 or less, about 1.38 or less, about 1.37 or less, about 1.36 or less , About 1.35 or less, about 1.34 or less, about 1.33 or less, about 1.32 or less, about 1.31 or less, about 1.30 or less, about 1.29 or less, about 1.28 or less, about 1.27 or less, about 1.26 or less, about 1.25 or less, about 1.24 or less, about 1.23 or less, about 1.22 or less, about 1.21 or less, about 1.2 or less, about 1.19 or less, about 1.18 or less, about 1.17 or less, about 1.16 or less, about 1.15 or less, about 1.14 or less, about 1.13 or less, about 1.12 or less, about 1.11 or less , About 1.1 or less, about 1.09 or less, about 1.08 or less, about 1.07 or less, or about 1.06 or less. By adjusting the ratio, it is possible to secure the performance of the desired polarizing plate.

In the case of the symmetric polarizing plate, it may have a contraction force in the same range as mentioned in the asymmetric polarizing plate in a direction parallel to the light absorption axis direction, and in a direction perpendicular to the light absorption axis direction, in the above-described symmetric polarizing plate It can have a contraction force in a range that can satisfy the contraction force ratio (S _P /S _{V) of.}

When the display panel is an LCD panel, as described above, first and second polarizing plates may be attached to both sides of the display panel, and at least one of the first and second polarizing plates may be the aforementioned asymmetric polarizing plates. have.

In the case of an LCD panel, the first and second polarizing plates may have their light absorption axes vertically arranged. In this structure, a target curved structure is efficiently formed by applying an asymmetric polarizing plate as at least one polarizing plate. And, the structure once formed can also be stably maintained.

When at least one of the first and second polarizing plates of the LCD panel is the asymmetric polarizing plate described above, the other polarizing plate is the same as the asymmetric polarizing plate (the ratio of the aforementioned contraction force (S _P / S _V ) is less than 0.9, or 1.5 It may be an excess polarizing plate), or the above-described symmetrical polarizing plate (a polarizing plate in which the ratio of the above-described contraction force (S _P /S _V ) is in the range of 0.9 to 1.5). In order to properly form and maintain a curved shape, in the case of an LCD panel, the asymmetric polarizing plate is applied as one of the first and second polarizing plates, and the symmetrical polarizing plate is applied as the other polarizing plate. I can.

In the case of an LCD panel, since polarizing plates are disposed on both sides of the panel, the contraction force relationship of both polarizing plates can be further adjusted in consideration of the efficiency of forming and maintaining a desired curved shape.

_{For example, in the case of an LCD panel, the ratio of the contraction force (S P1} ) in the direction of the light absorption axis of the first polarizing plate among the first and second polarizers _{(S V1} ) and the contraction force (S V1) in the direction perpendicular to the direction of the light absorption axis (S the absolute value of the difference _P1 / S _V1) and the ratio (S _P2 / S _V2) of the light absorption axis of second polarizer shrinkage force (S _P2) with the shrinkage force of the optical absorption axis in a direction normal to the direction (S _V2) Can be greater than or equal to 1.1. For example, when one of the first and second polarizing plates is an asymmetric polarizing plate and the other is a symmetric polarizing plate, the ratio (S _P1 /S _V1 or S _P2 /S _V2 ) to the asymmetric polarizing plate is _{The ratio (S P1} /S _V1 or S _P2 /S _V2 ) with respect to the symmetrical polarizing plate may have a larger value. In another example, the absolute value of the difference in the contractile force ratio is about 1.15 or more, about 1.2 or more, about 1.25 or more, about 1.3 or more, about 1.35 or more, about 1.4 or more, about 1.45 or more, about 1.5 or more, about 1.55 or more, about 1.6 Or more, about 1.65 or more, about 1.7 or more, about 1.75 or more, about 1.8 or more, about 1.85 or more, or about 1.9 or more. In another example, the absolute value of the difference in the contractile force ratio may be about 5 or less, about 4.5 or less, about 4 or less, about 3.5 or less, about 3 or less, or about 2.5 or less. With this design, it is possible to more effectively form and maintain a desired curved shape.

When the first and second polarizing plates are disposed on both sides of the display panel, the contracting force in the direction of the light absorption axis of the first polarizing plate (S _P1 ) and the contracting force in the direction perpendicular to the direction of the light absorption axis of the second polarizing plate (S _V2 ) The ratio of (S _P1 /S _V2 ) may be in the range of 0.5 to 2. Through this design, it is possible to effectively form and maintain a desired curved shape. The above relationship can be effectively applied when the first polarizing plate is an asymmetric polarizing plate and the second polarizing plate is a symmetric polarizing plate. The ratio (S _P1 /S _V2 ) is about 0.55 or more, 0.6 or more, 0.65 or more, 0.7 or more, 0.75 or more, 0.8 or more, 0.85 or more, or 0.9 or more, or 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less in another example , 1.5 or less, 1.4 or less, 1.3 or less, or may be about 1.2 or less.

When the first and second polarizing plates are disposed on both sides of the display panel, the contraction force in the direction perpendicular to the light absorption axis direction of the first polarizing plate (S _V1 ) and the contraction force in the light absorption axis direction of the second polarizing plate (S _P2 ) The ratio of (S _P2 /S _V1 ) may be in the range of 0.1 to 1.0. Through this design, it is possible to effectively form and maintain a desired curved shape. The above relationship can be effectively applied when the first polarizing plate is an asymmetric polarizing plate and the second polarizing plate is a symmetric polarizing plate. The ratio (S _P2 /S _V1 ) is, in another example, about 0.15 or more, about 0.2 or more, about 0.25 or more, about 0.3 or more, or about 0.35 or more, about 0.9 or less, about 0.8 or less, about 0.7 or less, about 0.6 or less , It may be about 0.5 or less or about 0.4 or less.

When the first and second polarizing plates are disposed on both sides of the display panel, the ratio _{of the contracting force (S P1} ) in the direction of the light absorption axis of the first polarizing plate and the contracting force (S _{P2) in the direction of the light absorption axis of the second polarizing plate (S P1} /S _P2 ) may be in the range of 0.5 to 2.0. Through this design, it is possible to effectively form and maintain a desired curved shape. The above relationship can be effectively applied when the first polarizing plate is an asymmetric polarizing plate and the second polarizing plate is a symmetric polarizing plate. The ratio (S _P1 /S _P2 ) is, in another example, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more, or about 1.9 or less, about 1.8 or less, about 1.7 or less, about 1.6 or less, about 1.5 or less, about 1.4 or less , It may be about 1.3 or less, about 1.2 or less, or about 1.1 or less.

When the first and second polarizing plates are disposed on both sides of the display panel, the contracting force (S _V1 ) in the direction perpendicular to the direction of the light absorption axis of the first polarizing plate and the contracting force in the direction perpendicular to the direction of the light absorption axis of the second polarizing plate may tomorrow ratio (S _V1 / _V2 S) range of 0.01 to 1.0 of (S _V2). Through this design, it is possible to effectively form and maintain a desired curved shape. The above relationship can be effectively applied when the first polarizing plate is an asymmetric polarizing plate and the second polarizing plate is a symmetric polarizing plate. The ratio (S _V1 /S _V2 ) is, in another example, about 0.05 or more, about 0.1 or more, about 0.15 or more, about 0.2 or more, about 0.25 or more, about 0.3 or more, or about 0.35 or more, or about 0.9 or less, about 0.8 or less , About 0.7 or less, about 0.6 or less, about 0.5 or less, or about 0.4 or less.

As described above, the asymmetric or symmetric polarizing plate applied to the display device of the present application is not particularly limited as long as it exhibits the above-described contraction force ratio, and a conventional polarizing plate may be applied.

A method of having the asymmetry or symmetry of the contraction force in a conventional polarizing plate is not particularly limited. For example, the asymmetry or symmetry of the desired contraction force may be secured by a method of adjusting the contraction force of each component included in the polarizing plate.

Typically, the polarizing plate basically includes a polarizing film. In the present specification, the terms polarizing film and polarizing plate have different meanings. The term polarizing film, for example, refers to a functional film that exhibits a polarizing function, such as a PVA (poly(vinyl alcohol)) film in which anisotropic material such as iodine is adsorbed and oriented, and the polarizing plate is different from the polarizing film. It means a device comprising an element. Other elements included with the polarizing film above include a protective film of a polarizing film, a viewing angle compensation film, a hard coating layer, a retardation film, an adhesive layer, an adhesive layer, an anti-glare layer, or a low reflection layer. And the like may be exemplified, but is not limited thereto.

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-based polarizing film can be manufactured through a washing and drying process, subject to each treatment such as swelling, dyeing, crosslinking, and stretching to the PVA-based film. As described above, since the PVA-based polarizing film is manufactured through a stretching process in the manufacturing process, it basically exhibits a high shrinking force in the stretching direction (usually in the direction of the light absorption axis), and an asymmetry showing a low shrinking force in a direction perpendicular thereto. Show.

The PVA-based polarizing film, which is manufactured through a conventional process and used in display devices such as LCD or OLED, has a contraction force in a direction parallel to the light absorption axis direction in the range of about 0.1N to 15N, and is perpendicular thereto. In one direction (the direction of the light transmission axis), it has an asymmetry indicating a low contraction force. The shrinking force in the light absorption axis direction of the PVA-based polarizing film is, in another example, 14.5 N or less, 14 N or less, 13.5 N or less, 13 N or less, 12.5 N or less, 12 N or less, 11.5 N or less, 11 N or less, 10.5 N or less, 10 N or less, 10 N or less, 9.5 N or less, or 9 N or less, or 0.5 N or more, 1 N or more, 2 N or more, 3 N or more, 4 N or more, 5 N or more, 6 N or more, or It may be 7 N or more.

The thickness of such a polarizing film 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 retardation film included in the polarizing plate together with the polarizing film, and the protective films are often polymer films.Since these polymer films are also manufactured by a stretching process, the contraction force in the main stretching direction is perpendicular to the main stretching direction. In some cases, it has low asymmetry compared to the contractile force in one direction. Therefore, when laminating a film (such as a protective film or a retardation film) having an asymmetry of the shrinking force to a polarizing film having an asymmetry of the shrinking force, if the directions of the large shrinking force of both films are parallel to each other, the asymmetry of the shrinking force as a whole is It is possible to manufacture a polarizing plate that is secured, and if the directions having a large shrinking force are made perpendicular to each other, a polarizing plate that is secured with symmetry can be manufactured.

In another example, as a method of applying a film having no asymmetry or weak shrinking force, a polarizing plate having asymmetry of the shrinking force may be manufactured. That is, when a film having no asymmetry or weak shrinking force is applied, the entire shrinkage force of the polarizing plate is determined by the asymmetric shrinking force characteristic of the polarizing film, and thus a polarizing plate having asymmetry can be obtained even in this case.

In one example, the polarizing plate of the present application as described above may basically include a polarizing film, a protective film, and an adhesive layer. The above components may be arranged in the order of a protective film, a polarizing film, and an adhesive layer. 1 schematically shows such a structure. 1, the polarizing plate may include a protective film 11 formed on one surface of the polarizing film 12 and an adhesive layer 13 formed on the other surface of the polarizing film 12.

In the present application, the above-described asymmetrical or symmetrical polarizing plate may be obtained by matching or orthogonal to each other in directions representing the main shrinking force in consideration of the shrinking force characteristics of the polarizing film and the protective film included in the polarizing plate. Alternatively, the asymmetric polarizing plate described above can be obtained even when there is no asymmetry of the shrinking force or a weak film is applied as a protective film. Hereinafter, in the present specification, the above contents are exemplarily described in a polarizing plate in which one polarizing film and one protective film are present, but the shape of the polarizing plate of the present application is not limited to the form described later. In other words, when a polarizing plate includes a film other than a polarizing film and a protective film, or even in a structure in which two protective films are arranged one sheet on each side of the polarizing film, the purpose of the objective is to consider the direction in which the main shrinking force of the included film appears. A symmetrical or asymmetrical polarizing plate can be easily manufactured.

For example, in order to obtain a desired asymmetrical or symmetrical polarizing plate in the structure in which the protective film and the polarizing film are sequentially arranged as described above, as a protective film, the shrinking force in the first direction in the plane is within the range of 0.5N to 10N. In addition, a film having a contraction force in a second direction perpendicular to the first direction may be lower than that in the first direction, or a film substantially similar to the contraction force in the first direction may be applied. For example, if the first direction of the film having a lower shrinking force in the second direction compared to the first direction is included in the polarizing plate so that it is approximately perpendicular to the light absorption axis direction of the polarizing film, a symmetrical polarizing plate is obtained and is approximately parallel. When included in a polarizing plate, an asymmetric polarizing plate can be obtained. Alternatively, in another example, an asymmetric polarizing plate can be obtained by applying a protective film having a substantially similar shrinking force in the first and second directions, and arranging the first or second direction parallel to the light absorption axis direction of the polarizing film. I can.

The in-plane first direction of the protective film referred to in the present specification is any one of MD (Machine Direction) and TD (transverse direction) directions when the protective film is a stretched polymer film, and the second direction is MD (Machine Direction). ) And a transverse direction (TD) direction. Accordingly, the first and second directions may be substantially perpendicular to each other.

In one example, the first direction of the protective film mentioned in the present specification may be the TD direction.

In the protective film in which the contraction force in the second direction is lower than or similar to that in the first direction, the in-plane contraction force in the second direction substantially perpendicular to the first direction may be in a range of about 0.05N to 4N. This second direction may be the MD (Machine Direction) direction of the protective film as described above. In another example, the shrinking force of the protective film in the second direction is about 0.1N or more, about 0.15N or more, or about 0.2N or more, or about 3.5N or less, about 3N or less, about 2.5N or less, or about 2N or less. May be.

In the protective film in which the contraction force in the second direction is lower than that in the first direction, the ratio (S1/S2) of the contraction force in the first direction (S1) and the contraction force in the second direction (S2) of the protective film is 15 It may be in the range of to 45. The ratio (S1/S2) is in another example about 16 or more, about 17 or more, about 18 or more, about 19 or more, about 20 or more, about 21 or more, or about 22 or more, or about 44 or less, about 43 or less, about 42 It may be about 41 or less, about 40 or less, about 39 or less, about 38 or less, about 37 or less, about 36 or less, about 35 or less, about 34 or less, or about 33 or less.

In the polarizing plate, a ratio (S _Pro /S _{PVA ) of the shrinking force (S PVA} ) of the polarizing film in the direction of the light absorption axis and the shrinking force (S _Pro ) of the protective film (S Pro /S PVA) may be in the range of 0.1 to 5. In another example, the ratio is about 0.2 or more, 0.3 or more, 0.4 or more, 0.45 or more, 0.5 or more, about 0.55 or more, about 0.6 or more, about 0.65 or more or about 0.7 or more, or about 4.5 or less, 4 or less, 3.5 or less, 3 It may be less than or equal to 2.5, less than or equal to 2, or less than or equal to 1.5. In the above, the shrinking force S _Pro of the protective film may be a shrinking force S1 in the first direction or a shrinking force S2 in the second direction.

In the present application, the protective film having the above-described shrinking force may be applied to a specific position of the polarizing plate to achieve the desired shrinking force characteristic of the entire polarizing plate. Although not limited thereto, in order to more effectively achieve the desired asymmetry or symmetry in the polarizing plate of the structure, in the present application, as a polymer film having a large mechanical asymmetry compared to the conventional case, a so-called high-stretch polyester film, etc. A known stretched PET (polyethyleneterephtalate) film can be used. As such a highly stretched PET (poly(ethylene terephthalate)) film, Toyobo's Super Retardation Film (SRF) film is known.

Therefore, the protective film may be a stretched polyester film.

Usually, a stretched PET film is one or more layers of a uniaxially stretched film produced by melting/extrusion of a PET-based resin and stretching, or a biaxially stretched film of one or more layers produced by stretching vertically and horizontally after film formation.

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. Other dicarboxylic acid components are not particularly limited, but 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.

Other diol components are not particularly limited, but propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol and/or polytetramethylene glycol, etc. Can be mentioned.

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. Further, as other copolymerization components, a dicarboxylic acid component containing a small amount of amide bonds, urethane bonds, ether bonds, carbonate bonds, or the like, 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 one reaction tank is completed, or a plurality of reaction tanks may be connected. In this case, the reactants are generally polymerized while being transferred between reaction tanks according to the degree of polymerization. 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 blending of these additives and for forming a film to be described later. 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.

Pellets made of dried PET resin are supplied to a melt-extrusion device, heated to a melting point or higher, and 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, depending on necessity. 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 is usually vertically stretched first in the extrusion direction at a temperature equal to or higher than the glass transition temperature. The 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 is usually 1.1 to 6 times or 2 to 5.5 times. Stretching can be completed in one cycle or, if necessary, can be divided into multiple times.

The vertically stretched film obtained in this way can be subjected to heat treatment after that. Subsequently, relaxation treatment can also be performed as needed. This heat treatment temperature is usually 150°C to 250°C, 180°C 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°C to 200°C or 120°C 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.

In the case of obtaining uniaxially stretched and biaxially stretched films, transverse stretching is usually performed by a tenter after longitudinal stretching treatment or, if necessary, after heat treatment or relaxation treatment. 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 is usually 1.1 to 6 times or 2 to 5.5 times. 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°C 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°C to 230°C, 110°C to 210°C, or 120°C 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.

In the uniaxial stretching and biaxial stretching treatment, after lateral stretching, in order to alleviate the deformation of the oriented main axis as typified by Boeing, heat treatment or stretching treatment may be performed again. The maximum value of the deformation with respect to the stretching direction of the oriented main axis by Boeing is usually within 45 degrees, within 30 degrees, or within 15 degrees. In addition, the extending|stretching direction here means the direction in which the extending|stretching large amount in longitudinal stretching or lateral stretching is carried out.

In biaxial stretching of a PET film, the case of the horizontal stretch ratio is usually performed slightly larger than the vertical stretch ratio, and in this case, the stretching direction refers to a direction perpendicular to the long direction of the film. In uniaxial stretching, it is usually stretched in the transverse direction as described above, and in this case, the stretching direction means a direction perpendicular to the same long direction.

The orientation main axis refers to the molecular orientation direction at an arbitrary point on the stretched PET film. In addition, the deformation|transformation of an orientation principal axis with respect to the extending|stretching direction means the angular difference between an orientation principal axis and a stretching direction. In addition, the maximum value thereof refers to the maximum value of the value in the vertical direction with respect to the long direction. The method of confirming the orientation main axis is known and can be measured using, for example, a retardation film/optical material inspection device RETS (manufactured by Otsuka Corporation) or a molecular orientation meter MOA (manufactured by Oji Keisoku Kiki Corporation). have.

The high-stretch polyester film as described above exhibits the properties of a protective film capable of achieving the desired shrinkage properties in the present application. In order to more effectively satisfy asymmetry or symmetry, the high-stretch polyester film may be subjected to a predetermined heat treatment to further control its properties. For example, in the polymer film, when heat treatment is performed at a temperature within a predetermined range based on the glass transition temperature (Tg) of the film, the shrinkage force is reduced. Therefore, by appropriately performing such heat treatment as necessary, a protective film having a shrinking force characteristic capable of effectively implementing a polarizing plate satisfying a desired symmetry or asymmetry can be obtained. For example, when the glass transition temperature of the protective film is Tg (unit: ℃), heat treatment at a temperature within the range of Tg-60 (℃) to Tg+50 (℃) to adjust the shrinkage force to the desired range. I can. In this case, the contraction force in the transverse direction (TD) rather than the so-called MD (Machine Direction) direction is generally controlled.

In other examples, the heat treatment temperature is Tg+45℃ or less, Tg+40℃ or less, Tg+35℃ or less, Tg+30℃ or less, Tg+25℃ or less, Tg+20℃ or less, Tg+15℃ or less, Tg +10℃ or less, Tg+5℃ or less, Tg℃ or less, Tg-5℃ or less, Tg-10℃ or less, Tg-15℃ or less, Tg-20℃ or less, Tg-25℃ or less, Tg-30℃ or less Alternatively, it may be about Tg-35°C or less, Tg-55°C or more, Tg-50°C or more, Tg-45°C or more, or Tg-40°C or more, wherein Tg is a glass transition temperature.

In the present application, if the heat treatment is performed, the heat treatment time may be adjusted in consideration of target characteristics without any particular limitation, and may be performed within a range of about 10 seconds to 1,000 seconds.

The thickness of the protective film applied in the present application 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.

The protective film applied in the present application may have 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.

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 panel such as an LCD panel or an OLED panel. 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. In the case of the pressure-sensitive adhesive, since the pressure-sensitive adhesive has a generally thin thickness and the effect of the shrinkage property on the overall shrinking force of the polarizing plate is insignificant, a conventional forming method may be applied in the process of forming the pressure-sensitive adhesive.

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 protective film and the polarizing film. Such an adhesive layer may be used for attaching the protective film to the polarizing film.

As the adhesive, for example, an adhesive layer used for attaching a polarizing film and a protective 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 a protective 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 protective film 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 a protective film exists between the polarizing film and the pressure-sensitive adhesive layer, a known protective film may be used as the protective film. Even in this case, it is possible to control the overall contraction force of the polarizing plate by designing the arrangement in the direction indicated by the main contraction force of the protective 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 protective film may be within the thickness range of the aforementioned protective film.

Between the polarizing film and the pressure-sensitive adhesive layer, an appropriate configuration may exist among the cured resin layer or the protective film, but it is advantageous to have the cured resin layer present in terms of securing the 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 protective 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 polarizing plate applied in the present application may have a known shape and size depending on the use.

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 may be formed in a different direction according to the application purpose, for example, the mode of the display panel, and the like. 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 exhibit a desired excellent effect even when formed in a thin thickness. For example, the polarizing plate may have a total thickness of 200 μm or less. The polarizing plate may include various elements described above, but the final thickness may be limited within the above range. By designing the thickness of the polarizing plate to be 200 μm or less, it is possible to effectively cope with various applications requiring a thin thickness. Usually, a polarizing plate is provided with a pressure-sensitive adhesive layer for applying the polarizing plate to a display device, and a release film is attached to the pressure-sensitive adhesive layer to protect the pressure-sensitive adhesive layer, or a surface protective sheet having a releasability temporarily is provided on the outermost side of the polarizing plate. It may be attached. The thickness of 200 μm or less referred to in the present application is the thickness excluding portions removed when the polarizing plate is finally applied to the display, such as the release film or the surface protection sheet. The thickness may be about 195 μm or less, about 190 μm or less, about 185 μm or less, about 180 μm or less, about 175 μm or less, about 170 μm or less, about 165 μm or less, about 160 μm or less, about 155 μm or less, about 150 μm or less, about 145 μm or less, or It may be about 140 μm or less. The lower limit of the thickness of the polarizing plate is not particularly limited, but generally about 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, 90 μm or more, 100 μm or more, 110 μm or more, or 120 μm or more.

The thickness mentioned in the present specification may mean the shortest distance, the maximum distance, or the average distance connecting the main surface and the main back surface of the object, and there may be manufacturing errors or deviations of a certain portion.

The display device of the present application basically includes the above-mentioned display panel and polarizing plate, and may further include other known configurations required.

The present application also relates to a method of manufacturing the curved display device as described above.

This manufacturing method may include, for example, heat-treating the display panel to which the polarizing plate is attached to at least one surface. In this case, the asymmetric polarizing plate described above may be applied as the polarizing plate.

In addition, when polarizing plates are present on both sides of the display panel like the above-described LCD panel, the manufacturing method may include heat-treating the display panel to which the first and second polarizing plates are attached to both sides, respectively. In this method, at least one of the first and second polarizing plates may be the aforementioned asymmetric polarizing plate.

When heat treatment is performed on a display panel to which an asymmetric polarizing plate having an asymmetric shrinking force characteristic is attached as described above, the polarizing plate undergoes asymmetric contraction due to the applied heat, and as a result, the display panel bends, forming a curved display device. Can be.

Details of the polarizing plate applied in the manufacturing method, that is, whether the polarizing plate is asymmetrical or symmetrical, and characteristics and arrangements of contracting force according to each of the polarizing plates may be the same as described for the display device.

The conditions under which the heat treatment is performed are not particularly limited.

For example, the heat treatment may be performed at a temperature of approximately 50°C to 90°C. In another example, the heat treatment temperature may be about 55° C. or more, about 60° C. or more, or about 65° C. or more, or about 85° C. or less, about 80° C. or less, or about 75° C. or less. In general, the higher the heat treatment temperature, the faster the asymmetric shrinkage of the polarizing plate may occur, and thus an appropriate heat treatment temperature may be set in consideration of this.

The heat treatment time is also not particularly limited as it is determined according to a desired curved shape or the like. That is, the longer the heat treatment time under the same heat treatment temperature condition, the more asymmetrical polarizing plate shrinks, so that a display device having a higher curvature can be manufactured.

The heat treatment time may be controlled within the range of 1 hour to 5 hours, but is not limited thereto.

The present application can provide a curved display device and a method of manufacturing the same, which can be manufactured through a simple and economical process, and stably maintains a designed curved shape.

1 shows an exemplary polarizing plate structure that can be applied in the present application.

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 Examples means the Machine Direction of a protective film as a stretched film or the light absorption axis direction of a polarizing film, unless otherwise specified, and TD is the Transverse direction of a protective film as a stretched film unless otherwise specified. Or it means the direction of the light transmission axis of the polarizing film.

1. How to measure curvature

The curvature of the display device was measured using a 2D Profile Laser Sensor. In addition, the curvature of the viewing side screen or the back side of the display device was measured in the above manner, and a larger value was described below.

2. Measurement of contraction force

The shrinkage force of the polarizing film, protective film, or polarizing plate mentioned in the present specification was measured in the following manner using a TA company's DMA equipment. The specimen was manufactured to have a width of about 5.3 mm and a length of about 15 mm, and the contraction force was measured after fixing both ends of the specimen in the longitudinal direction to the clamps of the measuring equipment. In the above, the length of the specimen is 15 mm excluding the part fixed to the clamp. As described above, after fixing the specimen to the clamp, the specimen was pulled and fixed to maintain 0.1% strain in the state of preload 0N, and then the contraction force applied when the strain 0.1% was maintained at a high temperature under the following temperature conditions was measured. The result of the contraction force was measured after 120 minutes after stabilization at 70° C. under the following temperature conditions. The contractile force was measured at a relative humidity maintained around 48%.

<Measurement temperature condition and time>

Temperature: 25℃ start → 70℃ stabilization after 3 minutes (no acceleration condition)

Measurement time: 120 minutes

Preparation Example 1. Preparation of PVA-based polarizing film

After swelling a PVA (poly(vinyl alcohol)) film (Japan Synthetic Company, polymerization degree of about 3,000) with a thickness of about 45 µm in a pure solution at a temperature of about 25°C, a temperature of about 35°C The dyeing process was performed for about 10 to 30 seconds in an iodine solution of. After that, after performing the cleaning process for about 20 seconds with a boric acid solution at a temperature of about 40°C (concentration: about 2% by weight), it is stretched about 6 times in a boric acid solution having a concentration of about 55°C and about 4.0% by weight, and then stretched. Afterwards, 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. As a result of measuring the contraction force (hereinafter, MD contraction force) in the light absorption axis direction of the prepared PVA-based polarizing film, it was about 7N to 9N.

Preparation Example 2. Preparation of polarizing plate (A)

PET (Polyethylene terephthalate) film (SKC, NRF, thickness: 50 μm, glass transition temperature: about 75° C.) was used as a protective film. The film was heat-treated at a temperature of about 70° C. to 80° C. for about 3 to 5 minutes, and then used. The shrinking force in the MD direction of the applied protective film was about 1.45 N, and the shrinking force in the TD direction was about 1.63 N.

The PET film was attached to one side of the PVA polarizing film of Preparation Example 1 using an epoxy-based ultraviolet curable adhesive (thickness: 2 μm to 3 μm). At the time of attachment, the TD direction of the PET film and the MD direction (the light absorption axis direction) of the PVA polarizing film were approximately parallel. Then, an epoxy-based hard coating layer was formed to a thickness of about 5 to 7 μm on the side of the PVA polarizing film to which the PET 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 shrinking force in the MD (light absorption axis direction) of the polarizing plate was about 7.21 N, and the shrinking force in the TD direction was about 2.99 N.

Preparation Example 3. Preparation of polarizing plate (B)

The same protective film as in Preparation Example 2 was heat-treated at a temperature of about 70° C. to 80° C. for about 1 minute to 3 minutes, and then used. The shrinking force in the MD direction of the film used was about 1.42 N, and the shrinking force in the TD direction was about 1.84 N. The PET film 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 TD direction of the PET film and the MD direction (the light absorption axis direction) of the PVA polarizing film were approximately parallel. Then, an epoxy-based hard coating layer was formed to a thickness of about 5 to 7 μm on the side of the PVA polarizing film to which the PET 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 shrinking force in the MD (light absorption axis direction) of the polarizing plate was about 7.34 N, and the shrinking force in the TD direction was about 2.94 N.

Preparation Example 4. Preparation of polarizing plate (C)

A PET (Polyethylene terephthalate) film (Mitsubishi, MCC PET, thickness: 50 μm, glass transition temperature: about 75° C.) was heat-treated at a temperature of about 70° C. to 80° C. for 1 minute to 3 minutes, and used as a protective film. The shrinking force in the MD direction of the protective film was about 2.02 N, and the shrinking force in the TD direction was about 2.31 N. The PET film 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 TD direction of the PET film and the MD direction (the light absorption axis direction) of the PVA polarizing film were approximately parallel. Then, an epoxy-based hard coating layer was formed to a thickness of about 5 to 7 μm on the side of the PVA polarizing film to which the PET 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 shrinking force in the MD (light absorption axis direction) of the polarizing plate was about 7.91 N, and the shrinking force in the TD direction was about 2.81 N.

Preparation Example 5. Preparation of polarizing plate (D)

A PET (Polyethylene terephthalate) film (Mitsubishi, MCC PET, thickness: 50 μm, glass transition temperature: about 75° C.) was heat-treated at a temperature of about 70° C. to 80° C. for 3 minutes to 5 minutes, and used as a protective film. The shrinking force in the MD direction of the protective film was about 1.91 N, and the shrinking force in the TD direction was about 2.28 N. The PET film 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 TD direction of the PET film and the MD direction (the light absorption axis direction) of the PVA polarizing film were approximately parallel. Then, an epoxy-based hard coating layer was formed to a thickness of about 5 to 7 μm on the side of the PVA polarizing film to which the PET 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 shrinking force in the MD (light absorption axis direction) of the polarizing plate was about 7.89 N, and the shrinking force in the TD direction was about 2.64 N.

Preparation Example 6. Preparation of polarizing plate (E)

A PET (Polyethylene terephthalate) film (Toyobo, SRF, thickness: 80 μm, glass transition temperature: about 81° C.) was heat-treated at a temperature of about 70° C. to 80° C. for 3 to 5 minutes to be used as a protective film. The shrinking force in the MD direction of the protective film was about 0.02 N, and the shrinking force in the TD direction was about 6.9 N. The PET film was attached to one side of the PVA polarizing film of Preparation Example 1 using an epoxy-based ultraviolet curable adhesive (thickness: 2 μm to 3 μm). At the time of attachment, the TD direction of the PET film and the MD direction of the PVA polarizing film (the direction of the light absorption axis) were substantially perpendicular to each other. Then, an epoxy-based hard coating layer was formed to a thickness of about 5 to 7 μm on the side of the PVA polarizing film to which the PET 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 shrinking force in the MD (light absorption axis direction) of the polarizing plate was about 7.79 N, and the shrinking force in the TD direction was about 8.05 N.

Preparation Example 7. Preparation of polarizing plate (F)

A PET (Polyethylene terephthalate) film (Toyobo, SRF, thickness: 80 μm, glass transition temperature: about 81° C.) was heat-treated at a temperature of about 70° C. to 80° C. for 3 to 5 minutes to be used as a protective film. The shrinking force in the MD direction of the protective film was about 0.03 N, and the shrinking force in the TD direction was about 6.7 N. The PET film 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 TD direction of the PET film and the MD direction of the PVA polarizing film (the direction of the light absorption axis) were substantially perpendicular to each other. Then, an epoxy-based hard coating layer was formed to a thickness of about 5 to 7 μm on the side of the PVA polarizing film to which the PET 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 shrinking force of the polarizing plate in the MD (light absorption axis direction) was about 7.73 N, and the shrinking force in the TD direction was about 7.28 N.

Manufacturing Example 8. Preparation of polarizing plate (G)

A PET (Polyethylene terephthalate) film (Toyobo, SRF, thickness: 80 μm, glass transition temperature: about 81° C.) was heat-treated at a temperature of about 70° C. to 80° C. for 3 to 5 minutes to be used as a protective film. The shrinking force in the MD direction of the protective film was about 0.04 N, and the shrinking force in the TD direction was about 6.9 N. The PET film 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 TD direction of the PET film and the MD direction of the PVA polarizing film (the direction of the light absorption axis) were substantially perpendicular to each other. Then, an epoxy-based hard coating layer was formed to a thickness of about 5 to 7 μm on the side of the PVA polarizing film to which the PET 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 shrinking force in the MD (light absorption axis direction) of the polarizing plate was about 7.9 N, and the shrinking force in the TD direction was about 8.09 N.

Example 1.

A polarizing plate (A) manufactured in Preparation Example 2 was attached to the top (viewer-side surface) of a known general LCD (Liquid Crystal Display) panel, and the polarizing plate (E) prepared in Preparation Example 6 was attached to the lower portion (backlight-side surface). Each was attached. In the above, the light absorption axes of the polarizing plates attached to the upper and lower portions of the panel were attached perpendicular to each other. Thereafter, the display panel to which the polarizing plates were attached to the upper and lower portions was heat-treated at a temperature of 70° C. for about 2 hours. A curved display device was implemented by asymmetric contraction of the polarizing plate by heat treatment, and specifically, a display device having a curvature of approximately 1801R at the back side of the image displayed surface was obtained.

Examples 2 to 8.

A curved display device was manufactured in the same manner as in Example 1, except that those shown in Table 1 below were applied as upper and lower polarizing plates. Table 1 below shows the curvature of the display device manufactured by the above method. In Table 1, the curvature of Examples 1 to 4 is the curvature of the short side of the back side of the image display surface of the display device, and the curvature of Examples 5 to 8 is the curvature of the long side of the image display surface of the display device.

Upper polarizer Lower polarizer curvature Example 1 Manufacturing Example 2 (polarizing plate (A)) Manufacturing Example 6 (polarizing plate (E)) 1801R Example 2 Manufacturing Example 3 (polarizing plate (B)) Manufacturing Example 6 (polarizing plate (E)) 1851R Example 3 Manufacturing Example 4 (polarizing plate (C)) Manufacturing Example 8 (polarizing plate (G)) 1863R Example 4 Manufacturing Example 5 (polarizing plate (D)) Manufacturing Example 7 (polarizing plate (F)) 1823R Example 5 Manufacturing Example 6 (polarizing plate (E)) Manufacturing Example 2 (polarizing plate (A)) 1521R Example 6 Manufacturing Example 6 (polarizing plate (E)) Manufacturing Example 3 (polarizing plate (B)) 1553R Example 7 Manufacturing Example 8 (polarizing plate (G)) Manufacturing Example 4 (polarizing plate (C)) 1581R Example 8 Manufacturing Example 7 (polarizing plate (F)) Manufacturing Example 5 (polarizing plate (D)) 1511R

Comparative Examples 1 to 6.

A curved display device was manufactured in the same manner as in Example 1, except that those shown in Table 2 below were applied as upper and lower polarizing plates.

When the polarizing plate was arranged in the manner shown in Table 2, the curved display device was not formed even by performing the heat treatment.

Upper polarizer Lower polarizer curvature Comparative Example 1 Manufacturing Example 6 (polarizing plate (E)) Manufacturing Example 6 (polarizing plate (E)) Curved display device not formed Comparative Example 2 Manufacturing Example 6 (polarizing plate (E)) Manufacturing Example 8 (polarizing plate (G)) Comparative Example 3 Manufacturing Example 8 (polarizing plate (G)) Manufacturing Example 6 (polarizing plate (E)) Comparative Example 4 Manufacturing Example 7 (polarizing plate (F)) Manufacturing Example 7 (polarizing plate (F)) Comparative Example 5 Manufacturing Example 7 (polarizing plate (F)) Manufacturing Example 6 (polarizing plate (E)) Comparative Example 6 Manufacturing Example 6 (polarizing plate (E)) Manufacturing Example 7 (polarizing plate (F))

11: protective film
12: polarizing film
13: adhesive layer

Claims (15)

Display panel; And a polarizing plate attached to one surface of the display panel, wherein the polarizing plate includes a ratio _{of a contraction force (S P} ) in a direction of a light absorption axis and a contraction force (S _{V ) in a direction perpendicular to the direction of the light absorption axis (S P} A curved display device with /S _V ) less than 0.9 or greater than 1.5. The method according to claim 1, wherein polarizing plates are attached to both surfaces of the display panel as first and second polarizing plates,
At least one of the first and second polarizing plates has a ratio (S _P / S _V ) _{of the contraction force (S P} ) in the direction of the light absorption axis and the contraction force (S _{V) in the direction perpendicular to the direction of the light absorption axis (S P / S V)} A curved display device less than or greater than 1.5. The curved display device of claim 2, wherein a direction of a light absorption axis of the first polarizing plate and a direction of a light absorption axis of the second polarizing plate are disposed perpendicular to each other. The method of claim 2, wherein the other polarizing plate of the first and second polarizing plates is _{the ratio of the contraction force (S P} ) in the direction of the light absorption axis and the contraction force (S _V ) in the _{direction perpendicular to the direction of the light absorption axis (S P} / S _V ) is a curved display device in the range of 0.9 to 1.5. _{The method of claim 2, wherein the ratio of the contraction force (S P1} ) in the direction of the light absorption axis of the first polarizing plate _{and the contraction force (S V1} ) in the direction perpendicular to the direction of the light absorption axis _{(S P1} /S _V1 ) of the second polarizing plate A curved display device in which an absolute value of a difference between the contraction force in the direction of the light absorption axis (S _P2 ) and the contraction force in the direction perpendicular to the direction of the light absorption axis (S _V2 ) (S _P2 /S _{V2) is 1.1 or more.} Claim 2, wherein the ratio of the first light contractile force of the absorption axis direction of the polarizing plate (S _P1) and contractile force (S _V2) of the second optical absorption axis in a direction normal to the direction of the polarizing plate (S _P1 / S _V2) is 0.5 in A curved display device within the range of to 2. The method of claim 2, wherein the ratio (S _P2 /S _{V1 ) of the contraction force (S V1} ) in the direction perpendicular to the direction of the light absorption axis of the first polarizing plate and the contraction force (S _P2 ) in the direction of the light absorption axis of the second polarizing plate is 0.1 A curved display device in the range of to 1.0. The method of claim 2, wherein the first polarizer the light absorption axis of the direction of contracting force (S _P1) and the ratio of the light absorption axis contractility (S _P2) in the direction of the second polarizing plate (S _P1 / S _P2) range of 0.5 to 2.0 Internal curved display device. _{The ratio of the contraction force (S V1} ) in the direction perpendicular to the direction of the light absorption axis of the first polarizing plate (S _{V1) and the contraction force (S V2} ) in the direction perpendicular to the direction of the light absorption axis of the second polarizing plate _{(S V1} /S _V2 ) is a curved display device in the range of 0.01 to 1.0. _{The ratio of the contraction force (S P1} ) in the direction of the light absorption axis of the first polarizing plate _{and the contraction force (S V1} ) in a direction perpendicular to the direction of the light absorption axis _{(S P1} / S _V1 ) is less than 0.9 or greater than 1.5,
A curved display device in which the ratio (S _P2 /S _{V2 ) of the contraction force (S P2} ) in the direction of the light absorption axis of the second polarizing plate _{and the contraction force (S V2} ) in the direction perpendicular to the direction of the light absorption axis (S P2 /S V2) is within the range of 0.9 to 1.5 . The curved surface according to claim 2, wherein the first and second polarizing plates are curved in which a smaller angle of the angle formed by one side of the polarizing plate and the light absorption axis of each polarizing plate is within a range of 0 degrees to 10 degrees or within a range of 80 degrees to 100 degrees. Display device. The curved surface of claim 2, wherein the first and second polarizing plates have a smaller angle of an angle between one side of the polarizing plate and a light absorption axis of each polarizing plate within a range of 35 degrees to 55 degrees or a range of 125 degrees to 145 degrees. Display device. Including the step of heat-treating the display panel to which the polarizing plate is attached to one side,
The polarizing plate, contracting force of the light absorption axis direction (S _P) and the light absorption axis direction and the ratio of the shrinkage force (S _V) of the vertical direction (S _P / S _V) is 0.9 or less than 1.5 more than the curved display device Manufacturing method. Including the step of heat-treating the display panel to which the first and second polarizing plates are respectively attached to both sides,
At least one of the first and second polarizing plates has a ratio (S _P / S _V ) _{of the contraction force (S P} ) in the direction of the light absorption axis and the contraction force (S _{V) in the direction perpendicular to the direction of the light absorption axis (S P / S V)} A method of manufacturing a curved display device of less than or greater than 1.5. The method of claim 13 or 14, wherein the heat treatment is performed at a temperature of 50°C to 90°C for 1 to 5 hours.

Images