KR20160049330A - Method for peeling a polarizing plate from a liquid crystal pannel - Google Patents

Abstract

The present invention relates to a method for peeling off a polarizing plate from a liquid crystal panel. The method comprises: a step of hatching a polarizing plate of a liquid crystal panel by laser; and a step of immersing the hatched polarizing plate in a solvent. Therefore, the method can easily peel off the polarizing plate from the liquid crystal panel.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for peeling a polarizing plate of a liquid crystal panel,

The present invention relates to a polarizing plate peeling method of a liquid crystal panel.

The liquid crystal display device includes a liquid crystal cell, a top plate polarizer, a bottom plate polarizer, and the like, and the upper plate and the lower plate polarizer are attached by adhesive layers above and below the liquid crystal cell. The polarizing plate comprises a polyvinyl alcohol (PVA) polarizer (or polarizing film) which is stretched in a predetermined direction and in which an iodine compound or a dichroic polarizing material is adsorbed and oriented, and a polarizing plate Polarizer protective film.

A pressure sensitive adhesive layer to be bonded to the liquid crystal cell on the polarizer protective film and a release film layer to be peeled off when the polarizing plate is attached to the liquid crystal cell are laminated before the polarizing plate is attached to the liquid crystal cell, Respectively. Therefore, the polarizing plate is attached to the liquid crystal cell by the pressure-sensitive adhesive layer after the release film is removed from the pressure-sensitive adhesive layer. After that, the surface protective film is peeled and removed when the function is finished.

 On the other hand, in the process of attaching the polarizing plate to the liquid crystal cell, contamination of the surface may occur due to contamination of foreign matter such as dust, and defects such as not attaching the polarizing plate in the correct direction may occur. In this case, It is necessary to peel off the polarizing plate from the liquid crystal cell for recycling.

Conventionally, a method of peeling a polarizing plate from a liquid crystal cell is a method in which one end of a polarizing plate is peeled off at an angle, the panel is attached to a roll shelf, and the peeled portion is fixed and peeled off by rotation of the roll. Another method is to fix the panel to the vacuum jig and peel off the polarizer.

In the conventional polarizing plate peeling method, there is a problem that the polarizing plate easily breaks in peeling depending on the adhesive force of the pressure-sensitive adhesive layer used in the thin display and the thickness of the polarizing plate. As a result, not only the reworking is difficult but also the panel itself is destroyed.

Accordingly, it is an object of the present invention to provide a polarizing plate peeling method in which a polarizing plate can be easily peeled off from a liquid crystal panel. Another object of the present invention is to provide a polarizing plate peeling method which can easily rework a liquid crystal panel.

In order to achieve the above object, the present invention provides a liquid crystal display comprising: (1) hatching with a laser onto a polarizing plate of a liquid crystal panel in which a liquid crystal cell, a pressure-sensitive adhesive layer and a polarizing plate are sequentially laminated; And (2) immersing the hatching liquid crystal panel in a solvent. According to a preferred embodiment of the present invention, the laser is CO ₂ Laser, and cross hatching with the laser. The hatching may have a spacing of 2 mm or less. According to a preferred embodiment of the present invention, the laser can be hatched on the liquid crystal panel using a laser in a direction perpendicular to the surface of the liquid crystal panel and the laser irradiation direction with respect to the liquid crystal panel. Further, according to a preferred embodiment of the present invention, (3) the step of cleaning the liquid crystal panel in which the polarizing plate is peeled off may be further included.

The present invention can provide a polarizing plate peeling method in which a polarizing plate can be easily peeled off from a liquid crystal panel. That is, the polarizing plate can be peeled off from the liquid crystal panel without limiting the thickness of the pressure-sensitive adhesive layer or the polarizing plate used for the liquid crystal panel.

In addition, the present invention can prevent the damage of the liquid crystal panel due to the breakage of the polarizer. Therefore, the liquid crystal panel in which the polarizing plate is peeled off can be reused.

1 is a schematic view of a polarizing plate peeling method according to a preferred embodiment of the present invention.
2 is a photograph showing the result of Experimental Example 1. Fig.
3 is a graph and a photograph showing the results of Experimental Example 2.
4 is a photograph showing the result of Experimental Example 3;

Hereinafter, the present invention will be described in detail. The following detailed description is merely an example of the present invention, and therefore, the present invention is not limited thereto.

In the present invention, hatching means irradiating an optical material such as a polarizing plate with a laser in an arbitrary pattern.

In the polarizing plate peeling method of the liquid crystal panel of the prior art, there is a problem that the polarizing plate easily breaks in peeling depending on the adhesive force of the pressure-sensitive adhesive layer used in the thin display and the thickness of the polarizing plate. As a result, not only the reworking is difficult but also the panel itself is destroyed.

Therefore, the inventors of the present invention have found that it is easy to make the polarizing plate peel off from the liquid crystal panel by using the laser and the solvent.

That is, the present invention provides a liquid crystal display comprising: (1) laser-hitting a polarizing plate of a liquid crystal panel in which a liquid crystal cell, a pressure-sensitive adhesive layer and a polarizing plate are sequentially laminated; And (2) immersing the liquid crystal panel having the pattern formed thereon in a solvent.

The liquid crystal panel of the present invention comprises at least one selected from a top plate polarizer and a bottom plate polarizer in a liquid crystal cell, and the top plate and the bottom plate polarizer are attached by an adhesive layer above and below the liquid crystal cell. When the liquid crystal panel of the present invention is attached to both the upper plate and the lower plate, it may be removed after the first side and the second side. For example, it is possible to remove the solvent immersion on the lower plate after dipping and removing the solvent on the upper plate after hitting both the upper and lower plates with a laser. At the time of hatching, the liquid crystal panel may be vertically erected and irradiated with two lasers at both sides. However, the present invention is not limited thereto.

1 is a schematic view of a polarizing plate peeling method of a liquid crystal panel according to a preferred embodiment of the present invention. Specifically, FIG. 1 (a) is cross-hatched with a laser on a liquid crystal panel in which a polarizing plate is laminated on a liquid crystal cell as a pressure-sensitive adhesive layer. 1 (b), the liquid crystal panel having a pattern formed by hatching with a laser is immersed in a solvent for 5 minutes to peel off. That is, the adhesive force of the pressure-sensitive adhesive layer is lowered by the solvent while being immersed in the solvent, and the polarizer is peeled from the edge. Finally, FIG. 1 (c) shows a state in which the polarizing plate is peeled off the liquid crystal panel.

Hereinafter, the method of peeling the polarizing plate of the present invention will be described.

First, the step (1) will be described.

In this step, a laser is irradiated from the top of the liquid crystal panel to form a hatch on the polarizing plate and the adhesive layer. According to a preferred embodiment of the present invention, the laser can be hatched in a direction perpendicular to the liquid crystal panel. That is, the laser can be irradiated in a direction perpendicular to the surface of the liquid crystal panel and the laser irradiation direction on the basis of the liquid crystal panel. If the liquid crystal panel is tilted at an angle other than 90 °, for example, 45 °, and then hatching with a laser, it is hatched with an angle of 45 °. In this case, since the other hatching lines except for one hatching line deviate from the center of the laser beam, the desired operation can not be performed. Therefore, a vertical direction is preferable.

In the present invention, the polarizing plate must be cut to a certain depth by a laser without damaging the liquid crystal panel with the polarizing plate attached thereto. Therefore, most of the energy of the laser beam must be absorbed by the polarizing plate, and it should be within a range that does not damage the liquid crystal panel even if energy is transmitted through the polarizing plate. According to a preferred embodiment of the present invention, the laser may be a CO ₂ laser or a UV laser, of which a CO ₂ laser is most preferred.

According to the embodiment of the present invention, a hatching is formed on the liquid crystal panel by a laser, and the hatching may be cross hatching. The hatching of the present invention can be carried out by any method which is generally usable, and it is possible to draw a pattern on a laser drive program and then hatch it using a scanner.

The depth of the hatching may correspond to the thickness of the polarizing plate and the adhesive layer, and may preferably be 10 to 500 탆. The larger the hatching interval, the smaller the number of hatching per unit area. According to a preferred embodiment of the present invention, the hatching may have an interval of 2 mm or less. However, the interval of the formed hatching may be variously adjusted depending on the type of the adhesive and the penetration of the solvent in the planar direction, and thus is not limited thereto. In addition, the shape of the hatching may be in the form of a square having no contact between single patterns, an arbitrary closed curve, and an intersecting grid shape, but is not limited thereto. According to a preferred embodiment of the present invention, the hatching may be in the form of a closed curve with a gap of 2 mm.

The energy density, energy output, scan speed, frequency and shape of the beam of the laser of the present invention are not particularly limited, and can be appropriately selected in consideration of the area of the polarizing plate to be peeled off, the peeling speed, the material and thickness of the pressure- According to a preferred embodiment of the present invention, the energy output of the laser may be 10 to 100 W, more preferably 50 to 70 W. The laser scanning speed may be 0.8 to 2.5 m / s, and preferably 1.3 to 1.6 m / s.

The laser energy density can be determined by the laser output, the scan speed, and the laser frequency when the laser beam size is fixed. According to another embodiment of the present invention, the laser energy density may be 5 to 15 J / cm ² , and more preferably 13 to 15 J / cm ² . If the energy density is less than 5 J / cm ² , there may be a problem that the solvent is not penetrated to the pressure-sensitive adhesive layer. If the energy density exceeds 15 J / cm ² , cracks may be generated in the liquid crystal cell. The above range is preferable.

 According to another embodiment of the present invention, the laser wavelength may be 5 to 25 um, preferably 8 to 12 um.

The number of the laser beams may be one or two or more. When a plurality of lasers are used, there is an advantage that the process can be performed more quickly. However, when a plurality of lasers are used, it is preferable to irradiate a predetermined amount of laser beams so that irradiated portions do not overlap each other. Also, in order to shorten the laser irradiation time, the shortest time hatching method considering the laser irradiation process may be applicable.

Next, the step (2) will be described.

In this step, the solvent penetrates into the pattern hatched in the step (1) to lower the adhesive strength of the pressure-sensitive adhesive layer. Thereby peeling off the edge of the polarizing plate pieces formed in accordance with the hatching pattern.

The solvent may be selected depending on the kind of the pressure-sensitive adhesive layer, and may preferably be selected from acetone and isopropyl alcohol, more preferably acetone. According to a preferred embodiment of the present invention, Preferably, the immersing step is performed for 2 to 20 minutes, preferably 2 to 10 minutes. If it is less than 2 minutes, there may be a problem that the solvent can not sufficiently penetrate, and if it exceeds 20 minutes, the panel may be damaged or the foreign matter may be severely left.

Meanwhile, the present invention may further include (3) washing the liquid crystal panel in which the polarizing plate is peeled off. That is, by further performing this step, the polarizing plate containing the pressure-sensitive adhesive layer in the liquid crystal cell can be peeled off without fail.

According to a preferred embodiment of the present invention, the regular cleaning can be done by wiping or drying using a paper or cloth.

Consequently, in the present invention, by using a laser and a solvent, the polarizing plate can easily be peeled off from the liquid crystal film.

Further, the maintenance process of the additional tool necessary for peeling can be omitted, so that it can be effective in carrying out the continuous process.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the embodiments of the present invention described below are illustrative only and the scope of the present invention is not limited to these embodiments. The scope of the present invention is indicated in the claims, and moreover, includes all changes within the meaning and range of equivalency of the claims. In the following Examples and Comparative Examples, "%" and "part" representing the content are based on weight unless otherwise specified.

Example  One

A 3D RF polarizing plate (thickness 150 탆) and LCD glass (100 mm x 100 mm x 1 mm) of LG Chem with laminated U1 adhesive films were prepared.

A CO ₂ laser having a wavelength of 10.6 μm, an energy output of 20 kHz, an energy output of 70 W, a scan speed of 1.5 m / s, and a CO ₂ laser beam diameter of 500 μm.

The prepared liquid crystal panel was cross-hatched in a checkerboard pattern so as to have hatching intervals of 1 mm and 2 mm, respectively, set by the laser. Next, the hatching liquid crystal panel was immersed in solvent acetone for 5 minutes, and immediately wiped off at room temperature using paper.

Example  2

12 pieces of a 3D RF polarizing plate (thickness 150 탆) and LCD glass (100 mm x 100 mm x 1 mm) of LG Chem with laminated U1 adhesive films were prepared.

The CO ₂ laser has a beam diameter of 500 μm, a wavelength of 10.6 μm, and an energy output and scan speed of 35 to 55 W and 1.3 to 2 m / s, respectively. Specifically, FIG. 3 shows cross hatching of 12 mm LCD glass with a hatching interval of 1 mm set by the laser. Next, the hatching liquid crystal panel was immersed in solvent acetone for 5 minutes, and immediately wiped off at room temperature using paper.

Example 3: Change in laser hatching pattern

25 pieces of a 3D RF polarizer (thickness 150 탆) and LCD glass (100 mm x 100 mm x 1 mm) of LG Chem with laminated U1 adhesive films were prepared.

The CO ₂ laser has a beam diameter of 500 μm and a wavelength of 10.6 μm. As shown in Table 1, the energy output and scan speed are 50 to 90 W and 1.3 to 2 m / s. Then, the hatching interval of the laser was set to 25 mm on the prepared 25 LCD glasses, and the square pattern was alternately hatched as shown in Fig. 4 (b) instead of Fig. 4 (a). Next, the hatching liquid crystal panel was immersed in solvent acetone for 5 minutes, and immediately wiped off at room temperature using paper.

Experimental Example  One

The above Example 1 was visually observed at room temperature and is shown in Fig.

2 is a photograph of laser hatching at intervals of 1 and 2 mm after attaching a polarizing plate to an LCD glass, (b) immersing the hatched portion in acetone at room temperature for 5 minutes, (c) , The portions with hatching intervals of 1 mm and 2 mm are photographs in which the polarizing plate is completely peeled off.

Experimental Example  2

Example 2 was visually observed at room temperature and is shown in Fig.

Referring to FIG. 3 (a), when the energy density, which is energy irradiated per unit area, exceeds the 'substrate damage threshold', cracking occurs in the substrate, although the peeling is very good. FIG. 3 (b) is a photograph showing an LCD glass in which a crack occurred at a point crossed according to laser irradiation conditions when cross hatching was performed. Therefore, the most preferable condition for facilitating peeling without substrate damage is 13 to 15 J / cm < ^{2 &} gt ;. However, this value may be different depending on the type and thickness of the polarizer and the pressure-sensitive adhesive used.

Experimental Example  3

Example 3 was visually observed, and is shown in Table 1 and FIG.

In the third embodiment, the square patterns were alternately peeled off. Thus, as shown in Table 1 and FIG. 4, it can be seen that, if the hatching pattern is appropriately changed in consideration of the beam size of the laser so that the intersection does not occur, peeling is easy without damage to the substrate. That is, as a result, it was easy to peel the polarizing plate under various laser irradiation conditions without damaging the substrate.

Referring to Fig. 4, (a) is a cross pattern hatching, which causes a crack at a crossing portion as shown in Fig. 3 (b) under the laser condition of the third embodiment. Therefore, in Experiment 3, (b) was hatched as a pattern to prevent crossing points. (c) A photograph of the polarizer peeled off at the time of hatching in the pattern (b).

Claims (10)

(1) A liquid crystal panel in which a liquid crystal cell, a pressure-sensitive adhesive layer and a polarizing plate are sequentially laminated On the polarizing plate Hatching with a laser; And
(2) immersing the hatching liquid crystal panel in a solvent. The method according to claim 1,
Wherein the liquid crystal panel is hatched on the liquid crystal panel using a laser in a direction perpendicular to the surface of the liquid crystal panel and the laser irradiation direction with respect to the liquid crystal panel. The method according to claim 1,
The laser is a CO ₂ Wherein the polarizer is a laser. The method according to claim 1,
Wherein the laser has an energy density of 5 to 15 J / cm ² . The method according to claim 1,
And cross hatching the laser beam with the laser beam. The method according to claim 1,
Wherein the hatching has an interval of 2 mm or less. The method according to claim 1,
Wherein the immersing step is performed for 2 to 10 minutes. The method according to claim 1,
Wherein the solvent comprises at least one selected from acetone and isopropyl alcohol. The method according to claim 1,
(3) cleaning the liquid crystal panel from which the polarizing plate has been peeled off. The method of claim 9,
Wherein the polarizing plate is cleaned with a paper or cloth.

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