KR20160017023A - Polarizer plate and display device comprising the same - Google Patents

Abstract

The present invention provides a polarizing plate and a display device including the same. The polarizing plate includes a polarizing film and a protective film prepared on both sides of the polarizing film. According to one embodiment of the present invention, the protective film having low shrinkage stress is used, so small force remains on the polarizing film.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a polarizing plate and a polarizing plate,

The present invention relates to a polarizing film; And a protective film provided on both sides of the polarizing film, and a display device including the polarizing plate.

Recently, with the remarkable development of the information technology industry, the liquid crystal display (LCD) industry, which is one of the core components of the IT industry, has been developed as a medium for transmitting various information It is developing.

Polarizer is one of the important parts of flat panel displays such as LCD and organic EL. The liquid crystal display panel has a structure in which polarizing films are bonded to both surfaces of a liquid crystal cell. In Fig. 1, a general form of such a polarizing plate is schematically illustrated. 1, the polarizing plate 1 includes protective films 2 and 3 attached to both sides of the central polarizing film 6 and the polarizing film 6 via adhesive layers 4 and 5 do. The protective films (2, 3) are disposed on the upper and lower sides of the polarizing film (6) to prevent the polarizing film (6) from being damaged.

Korean Patent Publication No. 2007-0091994

The present invention relates to a polarizing film; And a protective film provided on both sides of the polarizing film, and a display device including the polarizing plate.

One embodiment of the present disclosure relates to a polarizing element comprising a polarizing film; A first protective film provided on one side of the polarizing film; And a second protective film provided on the other side of the polarizing film,

And the shrinking force of the first protective film and the second protective film in at least one direction is 13 kgf or less per 1 mm width.

Another embodiment of the present invention provides a display device including the polarizer.

Another embodiment of the present disclosure provides a liquid crystal display device including the polarizer.

One embodiment of the present invention is advantageous in that a protective film having a low shrinking force is used, so that the residual force on the polarizing plate including the protective film is small.

In one embodiment of the present invention, when a polarizing plate including a protective film having a low shrinking force is used together with a glass substrate, the bending phenomenon that warps the glass substrate is advantageously reduced.

1 is a schematic view showing a general form of a polarizing plate.
2 is a photograph of a measuring instrument used in measuring retraction force in the present specification.
3 is an example of an elongation-force graph for measuring retraction force in the present specification.
4 and 5 are graphs for analyzing the correlation between the contracting force (X axis) and the bending (Y axis) of the polarizing plate in one embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

One embodiment of the present invention provides a protective film for a polarizing plate having a low shrinking force in at least one direction.

Polarizing plates manufactured through a series of processes may have residual forces applied during the process, which may cause deformation of the polarizing plate to shrink under high temperature or high temperature / high humidity conditions. Particularly as the thickness of the device is reduced in the liquid crystal cell, the glass used also becomes thinner, so that the influence of the force to deform the polarizer shrinks on the liquid crystal cell is increased and the defective due to the distortion of the liquid crystal cell is increasing. Accordingly, there is a need to reduce the bending shape of the liquid crystal cell by reducing the contracting force to deform the polarizing plate.

Polarizer manufacturers have been conducting a lot of studies to reduce the bending force at high temperature or high temperature and high humidity conditions. However, it has been very difficult to quantify the retraction force of the polarizing plate under high temperature or high temperature and high humidity conditions. The present applicant has made efforts to find a factor representing contractive force. As a result, the tensile strength is measured at normal temperature and humidity conditions, and the value obtained by converting the unit of kgf / mm ² into kgf / mm represents the contractive force I got it.

The applicant of the present invention obtained the results shown in FIG. 4 as a result of an experiment in which a polarizing plate attached to a glass substrate was left in an 80 ° C chamber for 24 hours and then subjected to a bending test, that is, an experiment to measure the degree of warping. Referring to FIG. 4, it can be seen that the bending phenomenon decreases as the shrinkage force of the polarizer decreases.

Further, the Applicant has found that the shrinking force of the polarizing plate itself is proportional to the sum of the individual shrinking forces of the layers constituting the polarizing plate. As a result, it was found that the lower the shrinking force of the protective film for polarizing plate, the more the bending phenomenon can be reduced.

An embodiment of the present disclosure provides a protective film for a polarizing plate wherein the contractive force in at least one direction is 13 kgf or less per 1 mm width.

In this specification, the lowering of the shrinking force of the polarizing plate protective film can further reduce the bending phenomenon that warps the substrate, so the lower limit of the shrinking force is not particularly limited, but if necessary, the shrinking force in at least one direction is 0 kgf Can be no more than 13 kgf.

The protective film for polarizing plate may be at least one of a COP (cycloolefin polymer) film, an acrylic film, a TAC (triacetylcellulose) film, a COC (cycloolefin copolymer) film, a PNB (polynorbornene) film, and a PET (polyethylene terephthalate) ≪ / RTI >

The polarizing plate protective film may include a COP (cycloolefin polymer) film having a shrinking force of at least 10 kgf per 1 mm width in at least one direction.

In this specification, the lowering of the shrinking force of the polarizing plate protective film can further reduce the bending phenomenon that warps the substrate, so the lower limit of the shrinking force is not particularly limited, but if necessary, the shrinking force in at least one direction is 0 kgf Can be less than 10 kgf.

The present invention relates to a polarizing film; A first protective film provided on one side of the polarizing film; And a second protective film provided on the other side of the polarizing film.

The present invention provides a polarizing plate comprising a protective film having a low shrinking force.

The present invention provides a polarizing plate comprising a protective film having a low shrinking force in an absorption axis direction or a transmission axis direction.

The present invention relates to a polarizing film; A first protective film provided on one side of the polarizing film; And a second protective film provided on the other side of the polarizing film,

And the shrinking force of the first protective film and the second protective film in at least one direction is 13 kgf or less per 1 mm width. In this case, there is an advantage that the bending phenomenon that warps the substrate can be reduced.

In other words, the shrinking force of the first protective film in at least one direction is not more than 13 kgf per 1 mm width, and the shrinking force of the second protective film in at least one direction is not more than 13 kgf per 1 mm width .

In the present specification, " at least one direction " may include all directions and is not particularly limited.

The " at least one direction " may include a machine direction, which is the direction in which the protective film is moved in the production, or a direction perpendicular to the machine direction, if necessary.

The " at least one direction " may include a longitudinal direction, which is a direction in which the protective film is wound on a storage roll at the time of manufacturing the protective film, or a width direction perpendicular to the longitudinal direction.

The " at least one direction " may include a direction in which the polarizing plate is bent under high temperature and high humidity conditions, as required, at a temperature of 25 DEG C and a relative humidity of 50%.

In the present specification, " the direction in which the polarizing plate is bent " means the direction of the line including the longest point of the vertical line drawn to the reference surface among the points of the edge of the polarizing plate. In this case, the direction of the line may be the machine direction including the longest point of the vertical line drawn to the reference surface, or the direction perpendicular to the machine direction.

In this specification, the condition of "high temperature and high humidity than the condition of temperature 25 ° C. and relative humidity of 50%" has a phenomenon in which the polarizing plate is bent with respect to the reference surface at a temperature and a relative humidity higher than 25 ° C. and 50% It is not particularly limited. For example, as one example of the present invention, the amount of bending was measured under the condition that the temperature was 80 DEG C or the condition where the temperature and the relative humidity were 60 DEG C and 90%, respectively.

The " at least one direction " may include at least one of an absorption axis direction of the polarizing film and a transmission axis direction of the polarizing film, if necessary.

Here, the contractive force means a force which is intended to be restored to its original state after the film is deformed. Since the force at the time of actual shrinkage is difficult to measure, it is necessary to estimate the shrinkage force by measuring the force necessary for forcibly stretching (stretching) the film. In other words, it shows that the tensile strength shows the contractive force. As a result, it is judged that the tensile strength can cope with the contractive force.

At this time, the contractile force (tensile strength) is measured by the following method.

1. After cutting the sample to a width of 10 mm and a length of 150 mm in an environment of normal temperature (25 ° C) and normal humidity (50%), the sample was set vertically as shown in FIG.

2. Fix the bottom of the sample and pull the opposite side up.

3. An elongation-force graph was obtained as shown in FIG. 3 by simultaneously measuring the percentage strain and the load on the film while the sample was being drawn by force.

4. In the elongation-force graph, the shrinkage force was obtained at the steepest slope of the tangent line.

In this specification, there is an advantage that the polarizing plate shrinks and the bending phenomenon of the glass is reduced due to residual force remaining in the protective film by using a protective film having a low shrinking force.

The material and the manufacturing method of the polarizing film are not particularly limited, and conventional materials and manufacturing methods known in the art can be used.

In one embodiment of the present invention, the polarizing film may be a polyvinyl alcohol polarizing film.

The smaller the shrinking force of the polarizing film is, the smaller the shrinking force of the polarizing plate is. The smaller the shrinking force of the polarizing film is, the more the shrinkage of the polarizing plate and the bending phenomenon of the glass are reduced.

In the embodiment of the present invention, since the bending phenomenon that warps the substrate can be further reduced as the shrinking force of the polarizing film in the absorption axis direction becomes lower, the range of shrinking force is not particularly limited, but the shrinking force is 0 kgf Can be less than 70 kgf. If necessary, the shrinking force of the polarizing film in the absorption axis direction may be 25 to 45 kgf per 1 mm width.

In one embodiment of the present invention, since the bending phenomenon in which the substrate is bent can be further reduced as the shrinking force of the polarizing film in the transmission axis direction is lower, the range of the shrinking force is not particularly limited, but the shrinking force is 0 kgf It can be less than 40 kgf. If necessary, the shrinking force of the polarizing film in the transmission axis direction may be 5 to 15 kgf per 1 mm width.

The inventors of the present invention found that the shrinking force decreases as the thickness of the film decreases as the thickness of the film decreases.

Accordingly, the thinner the thickness of the polarizing film is, the smaller the shrinking force is, and the bending phenomenon of bending the substrate is further reduced, so the numerical range of the thickness of the polarizing film is not particularly limited. The thickness of the polarizing film may be more than 0 탆 and less than 50 탆. In this case, the bending phenomenon that warps the substrate may be reduced. If necessary, the thickness of the polarizing film may be 5 to 40 [mu] m and may be 10 to 30 [mu] m if necessary.

The first protective film is not particularly limited as long as the protective film has a shrinking force that satisfies the range of the present invention, and conventional materials and manufacturing methods known in the art can be used.

In one embodiment of the present invention, the first protective film may include at least one film, and may be a COP (cycloolefin polymer) film, an acrylic film, a TAC (triacetylcellulose) film, a COC (cycloolefin copolymer) PNB (polynorbornene) -based film, and PET (polyethylene terephthalate) -based film.

In one embodiment of the present invention, the first protective film may include at least one film, and may optionally include a COP (cycloolefin polymer) film having a shrinkage force of 10 kgf or less per 1 mm width.

And a pressure sensitive adhesive layer disposed on the first protective film. Here, " on the first protective film " means the opposite side of the side on which the polarizing film is provided with respect to the first protective film.

The pressure-sensitive adhesive layer is provided for application to a display device such as a liquid crystal display device.

For example, the surface provided with the pressure-sensitive adhesive layer may be adhered to a liquid crystal cell of a liquid crystal display element. At this time, it is preferable that the first protective film adhered to the liquid crystal cell has a specific retardation for the viewing angle compensation.

The first protective film may include at least one additive selected from a UV absorber, an anti-blocking agent, a lubricant, an antistatic agent and a stabilizer, if necessary.

At least one of an antireflection layer, a low reflection coating layer, a UV absorbing layer, a brightness enhancement layer, an antistatic coating layer, an antiglare layer, a liquid crystal coating layer and a hard coating layer may be additionally provided on the upper surface or the lower surface of the first protective film. .

The first protective film and the polarizing film may be adhered by using an aqueous adhesive or a non-aqueous adhesive.

In one embodiment of the present invention, the second protective film may include at least one film, and may be a COP (cycloolefin polymer) film, an acrylic film, a TAC (triacetylcellulose) film, a COC (cycloolefin copolymer) PNB (polynorbornene) -based film, and PET (polyethylene terephthalate) -based film.

According to one embodiment of the present invention, the second protective film may include at least one film, and may include a COP (cycloolefin polymer) having a shrinking force of 10 kgf or less per mm width, if necessary.

The second protective film may include at least one additive selected from a UV absorber, an anti-blocking agent, a lubricant, an antistatic agent and a stabilizer, if necessary.

At least one layer of an antireflection layer, a low reflection coating layer, a UV absorption layer, a brightness enhancement layer, an antistatic coating layer, an anti glare layer, a liquid crystal coating layer and a hard coating layer may be additionally provided on the upper surface or the lower surface of the second protective film. .

The second protective film and the polarizing film may be adhered by using an aqueous adhesive or a non-aqueous adhesive.

When the pressure-sensitive adhesive layer formed on the first protective film is adhered to the liquid crystal cell, the second protective film is positioned relatively to the outside. In this case, it is preferable that the second protective film includes a UV absorbent or a UV absorbing layer on the upper or lower surface of the second protective film.

When the polarizing plate is provided on both sides of the liquid crystal cell, a hard coating layer, a low reflection coating layer, and a hard coating layer are formed on the upper or lower surface of the second protective film (protective film positioned at the outermost periphery) of the upper polarizer plate, At least one layer of the anti glare layer may be further provided.

When the polarizing plate is provided on both sides of the liquid crystal cell, a brightness enhancement layer is additionally provided on the upper surface or the lower surface of the second protective film (protective film positioned at the outermost periphery) of the lower polarizer plate relatively closer to the ground with respect to the liquid crystal cell .

The inventors of the present invention found that the shrinking force decreases as the thickness of the film decreases as the thickness of the film decreases.

In the present invention, the thinner the thickness of the protective film is, the further the bending phenomenon that warps the substrate can be further reduced, so the numerical range of the thickness of the protective film is not particularly limited. The thickness of the protective film may be greater than 0 袖 m and less than 60 袖 m. In this case, the bending phenomenon that warps the substrate may be reduced.

If necessary, the thickness of the protective film may be in the range of 15 to 45 μm, and may be 20 to 30 μm if necessary.

The thickness of the protective film made of acrylic film or TAC film is preferably 15 to 45 μm. In this case, the shrinking force of the protective film made of an acrylic film or a TAC film can be 13 kgf or less per 1 mm width, and the bending phenomenon that warps the substrate can be reduced.

Another embodiment of the present invention provides a display device including the polarizer.

The display device may include a touch panel, a light emitting diode (LED), an organic light emitting diode (OLED), a liquid crystal display (LCD), and a thin film transistor liquid crystal display (LCD) Liquid Crystal Display, LCD-TFT).

The thickness of the glass substrate provided in the display device may be 0.1 mm to 0.7 mm, and may be selected according to the applied device.

Another embodiment of the present disclosure provides a liquid crystal display device including the polarizer.

The liquid crystal display device may include a liquid crystal cell and the polarizer provided on one side or both sides of the liquid crystal cell.

At this time, the liquid crystal cell and the polarizing plate can be bonded by the pressure-sensitive adhesive layer provided on the first protective film of the polarizing plate.

The present specification will be described in more detail with reference to the following examples and comparative examples. However, the following examples and comparative examples are intended to illustrate the present specification, and the present invention is not limited thereto.

[Example]

[Example 1]

Hard coating layer COP Polarizer film COP Liquid crystal coating layer The pressure-sensitive adhesive layer (PSA)

A COP film having a thickness of 23 占 퐉 was used as the first protective film, and a liquid crystal coating layer having a thickness of 1 占 퐉 was formed on one side of the first protective film. In the COP film formed with the liquid crystal coating layer, the shrinking force in the absorption axis direction is 6 kgf per 1 mm width and the shrinking force in the transmission axis direction is 7 kgf per 1 mm width.

A pressure-sensitive adhesive layer having a thickness of 22 mu m was formed on the liquid crystal coating layer.

Further, a COP film having a thickness of 40 占 퐉 was used as the second protective film, and a hard coating layer having a thickness of 7 占 퐉 was formed on one side of the second protective film. The shrinking force of the COP film formed with the hard coat layer in the absorption axis direction is 6 kgf per 1 mm width and the shrinking force in the transmission axis direction is 6 kgf per 1 mm width.

Thereafter, the first protective film and the second protective film were adhered to both sides of the polyvinyl alcohol polarizing film having a thickness of 12 μm with the structure shown in Table 1, using a non-aqueous adhesive, to prepare a polarizing plate.

[Comparative Example 1]

Hard coating layer Acrylic film Polarizer film COP Liquid crystal coating layer The pressure-sensitive adhesive layer (PSA)

A COP film having a thickness of 23 占 퐉 was used as the first protective film, and a liquid crystal coating layer having a thickness of 1 占 퐉 was formed on one side of the first protective film. In the COP film formed with the liquid crystal coating layer, the shrinking force in the absorption axis direction is 6 kgf per 1 mm width and the shrinking force in the transmission axis direction is 7 kgf per 1 mm width.

A pressure-sensitive adhesive layer having a thickness of 22 mu m was formed on the liquid crystal coating layer.

Further, an acrylic film having a thickness of 40 μm was used as the second protective film, and a hard coating layer having a thickness of 5 μm was formed on one side of the second protective film. The shrinking force of the acrylic film formed with the hard coat layer in the absorption axis direction is 20 kgf per 1 mm width and the shrinking force in the transmission axis direction is 19 kgf per 1 mm width.

Thereafter, the first protective film and the second protective film were adhered to both sides of the polyvinyl alcohol polarizing film having a thickness of 12 탆 in the structure shown in Table 2, using a non-aqueous adhesive, to prepare a polarizing plate.

[Comparative Example 2]

Anti glare layer Acrylic film Polarizer film Acrylic film The pressure-sensitive adhesive layer (PSA)

An acrylic film having a thickness of 40 占 퐉 was formed as a first protective film. In the acrylic film, the shrinking force in the absorption axis direction is 16 kgf per 1 mm width and the shrinking force in the transmission axis direction is 17 kgf per 1 mm width.

A pressure-sensitive adhesive layer having a thickness of 22 mu m was formed on one side of the first protective film.

Further, an acrylic film having a thickness of 40 占 퐉 was used as the second protective film, and an antiglare layer having a thickness of 5 占 퐉 was formed on one side of the second protective film. The shrinking force of the acrylic film formed with the anti-glare layer in the absorption axis direction is 19 kgf per 1 mm width and the shrinking force in the transmission axis direction is 21 kgf per 1 mm width.

Thereafter, the first protective film and the second protective film were adhered to both sides of the polyvinyl alcohol polarizer film having a thickness of 12 μm using the non-aqueous adhesive agent as shown in Table 3 to prepare a polarizing plate.

 [Experimental Example 1]

Bending test under heat-resistant condition (80 ° C, 24 hours)

Samples were prepared in the size of 200 mm x 150 mm in the polarizing plate prepared in the above Examples and Comparative Examples. At this time, the sample was prepared so that the length in the direction of the absorption axis was long, that is, the length in the direction of the absorption axis was 200 mm.

The thus prepared polarizer of 200 mm x 150 mm size was attached to the center of a glass substrate (0.4 mm thick) having a size of 210 mm x 160 mm to prepare a sample. Thereafter, the sample adhered to the glass substrate was left in a chamber at 80 캜 for 24 hours. After leaving for 24 hours in the chamber, it was taken out and then left at room temperature (25 degrees, 50% humidity) for 24 hours, and then bending was measured.

At this time, the degree of bending is measured by placing the sample on a flat stone table (placing the glass substrate against the stone table) And measured using a three-dimensional measuring machine. The maximum value of the distance from the staggered half was defined as the amount of bending of the polarizer. FIG. 4 is a graph showing the relationship between the retraction force (X axis) and the bending amount (Y axis) in the bending direction based on the results.

Example 1 Comparative Example 1 Comparative Example 2 PSA opposite film 6 kgf / mm 20 kgf / mm 19 kgf / mm Polarizer film 35 kgf / mm 35 kgf / mm 35 kgf / mm PSA side film 6 kgf / mm 6 kgf / mm 16 kgf / mm Total (polarizer) 47 kgf / mm 61 kgf / mm 70 kgf / mm Bending amount 4.6 mm 5.6 mm 6.5 mm

[Experimental Example 2]

Bending test under moist heat (60 캜, humidity 90%, 24 hours)

Same as Experimental Example 1 except that the sample adhered to the glass substrate was left in a chamber at 60 캜 and a humidity of 90% for 24 hours. The results are shown in Table 8 below, and a graph of the correlation between the contracting force (X axis) and the bending (Y axis) in the bending direction is shown in FIG.

Example 1 Comparative Example 1 Comparative Example 2 PSA opposite film 6 kgf / mm 20 kgf / mm 19 kgf / mm Polarizer film 35 kgf / mm 35 kgf / mm 35 kgf / mm PSA side film 6 kgf / mm 6 kgf / mm 16 kgf / mm Total (polarizer) 47 kgf / mm 61 kgf / mm 70 kgf / mm Bending amount 1.2 mm 2.4 mm 3.0 mm

1: polarizer
2, 3: Protective film
4, 5: Adhesive layer
6: Polarizing film
7: Pressure-sensitive adhesive

Claims (8)

A polarizing film; A first protective film provided on one side of the polarizing film; And a second protective film provided on the other side of the polarizing film,
And the shrinking force of the first protective film and the second protective film in at least one direction is 13 kgf or less per 1 mm width. The polarizing plate according to claim 1, wherein the polarizing film is a polyvinyl alcohol polarizing film. [3] The method of claim 1, wherein the first protective film and the second protective film each comprise at least one of a COP (cycloolefin polymer) film, an acrylic film, a TAC (triacetylcellulose) film, a COC (cycloolefin copolymer) And a PET (polyethylene terephthalate) film. [4] The polarizing plate of claim 3, wherein at least one of the first protective film and the second protective film comprises a COP (cycloolefin polymer) -based film having a shrinking force of 10 kgf or less per mm width. The method of claim 1, further comprising a pressure-sensitive adhesive layer disposed on the first protective film, wherein the second protective film comprises a UV absorber, an anti-blocking agent, a lubricant, an antistatic agent, Wherein the polarizer comprises at least one of the above additives. [5] The method of claim 1, wherein the anti-reflection layer, the anti-glare layer, the liquid crystal coating layer, and the hard coating layer are formed on at least one of the first protective film and the second protective film. Wherein at least one layer selected from the group consisting of a first polarizing plate and a second polarizing plate is additionally provided. A display device comprising the polarizer of any one of claims 1 to 6. A liquid crystal display device comprising the polarizer of any one of claims 1 to 6.

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