JP2005258065A - Method for manufacturing polarizing plate and adhering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a polarizing plate and a device therefor. <P>SOLUTION: The polarizing plate 116 is equipped with a polarizing film 112 and a protection film 114. First, the protection film 114 is coated with a polyurethane adhesive by a coating device 222. Thereafter, the protection film 114 coated with the polyurethane adhesive is baked by a baking device 226. Finally, the baked protection film 114 and the polarizing film 112 are heated and press-fit by a heating roller 224. Thus, the polarizing plate 116 is formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a polarizing plate and an adhesive device.

  The liquid crystal display has advantages such as high image quality, small volume, light weight, low voltage driving, low power consumption, and wide application range. Therefore, it is widely used in consumer electronic products or computer products such as small and medium-sized portable TVs, mobile phones, video cameras, notebook computers, desktop displays, and projection TVs, and gradually becomes a cathode ray tube (CRT). ) Replaced the mainstream display.

  In a liquid crystal display, a polarizing plate is one of main components of a liquid crystal panel. FIG. 1A shows a conventional polarizing plate adhesive method, and FIG. 1B shows a conventional polarizing plate adhesive device. In the following description, FIGS. 1A and 1B are referred to simultaneously.

  The polarizing plate is constituted by adhering a polarizing film and a protective film. In the prior art, a polarizing film 112 is manufactured by dyeing, stretching and modifying a polyvinyl alcohol (PVA) film, and triacetyl cellulose (TAC) is used as a material for the protective film 114 (step). 102). Thereafter, an adhesive such as polyvinyl alcohol adhesive is applied between the protective film 114 and the polarizing film 112 using the die 122 (step 104), and the protective film 114 coated with the adhesive by the roller 124 is used. And the polarizing film 112 are pressure-bonded (step 106) to obtain the polarizing plate 116. Finally, the polarizing plate 116 is baked by the baking furnace 126 to further adhere the protective film 114 and the polarizing film 112 (step 108).

  In the conventional adhesive method, the baking time is very long (about 20 minutes), and the polarizing plate 116 is produced by the transport belt method. Therefore, the baking process is performed using the baking furnace 126 in the transport process. A long firing time means that the firing furnace 126 becomes long (about 50 meters), resulting in waste of equipment cost and equipment space, and increased material wear. In addition, due to an excessively long baking time, the above-mentioned film was easily shrunk by heat, and the quality and production yield of the polarizing plate were lowered.

  Patent Document 1 discloses “a polarizing film manufacturing method, a polarizing film, an optical film, and an image display device”. As shown in FIG. 3, the film layer on the low softening point layer 304b side of the protective film 304 is bonded to at least one surface of the polarizer 302 and directly heat-pressed and laminated. A polarizing film can be manufactured without using it. The protective film 304 is appropriately selected from materials having different softening points, and is formed of two or more film layers such as a high softening point layer 304a and a low softening point layer 304b.

  However, the technique disclosed in Patent Document 1 has at least two drawbacks. First, since the temperature of the liquid crystal panel is raised by the thermal energy generated by the light source of the backlight, the low softening point material in the polarizing plate adhered in the prior art easily melts again at a high temperature and the panel is heated. Destroyed the quality. Such a situation easily occurred particularly in a large-sized liquid crystal panel using a light source having high thermal energy.

  Secondly, when the protective film itself is melted to adhere the polarizer and the protective film, the state of the melted protective film becomes almost solid and poor in fluidity. It was difficult to get into defects on the film surface. For this reason, defects inside the polarizing film cannot be repaired by the adhesion step, and it is difficult to improve the optical properties of the polarizing film.

Taiwan Patent No. 565716 Specification

  The object of the present invention is to change the pressure-sensitive adhesive step sequence, increase the production efficiency of the polarizing plate to reduce wear, and combine the pressure-sensitive adhesive application and the pre-baking step to combine the heat-resistant function of the polarizing film. Is to improve the optical properties of the polarizing plate, and to provide a manufacturing method of the polarizing plate to increase the production yield.

  Another object of the present invention is to provide an adhesive device for a polarizing plate, which is baked after application of an adhesive and subjected to overheat pressure bonding, thereby shortening the time required for adhesion and greatly reducing the equipment space required for the adhesion device. It is to provide.

  In order to achieve the above object, the present invention provides a method for producing a polarizing plate and an adhesive device. The polarizing plate includes a polarizing film and a protective film. First, a polyurethane adhesive is applied on the protective film by a coating device. Then, the protective film which has a polyurethane (Polyurethane: PU) adhesive agent is baked with a baking apparatus. Finally, the fired protective film and the polarizing film are heat-pressed with a heating roller.

  According to a preferred embodiment of the present invention, the material of the polarizing film is polyvinyl alcohol, and the material of the protective film is triacetyl cellulose, a cyclic olefin copolymer (COC) and a cyclic olefin polymer ( cyclic olefin polymer (COP). The application device is any one of a die, a wire bar, and a gravure. The temperature of the baking apparatus is 30 to 55 ° C, preferably 45 ° C, and the temperature of the heating roll is 110 to 150 ° C, preferably 120 ° C. When the polyurethane adhesive is aqueous, the solvent is water, and when the polyurethane adhesive is oily, the solvent contains at least one selected from the group consisting of acetone, methyl ethyl ketone, and tetrahydrofuran.

  In the present invention, the time sequence required for the firing step can be shortened by changing the step order of the conventional method for producing a polarizing plate and using a polyurethane adhesive as an adhesive. When the polarizing plate is adhered according to the present invention, the baking time is shortened, so that the problems of the prior art, in which the baking time is too long and the quality of the film is lowered, can be improved. In addition, since the present invention can shorten the polarizing plate process time, not only can the production efficiency and yield of the polarizing plate be improved, but also the equipment space required for the adhesive device can be reduced at the same time. Can also be reduced.

  FIG. 2A is a flowchart showing a method for manufacturing a polarizing plate in an embodiment of the present invention. FIG. 2B is a diagram showing a polarizing plate adhesive device in an example of the present invention. In the following description, reference is made to FIGS. 2A and 2B.

  The polarizing plate includes a polarizing film and a protective film. First, a polarizing film 112 is manufactured by dyeing, stretching and modifying a polyvinyl alcohol film, and the protective film 114 is made of any one of triacetyl cellulose, cyclic olefin copolymer and cyclic olefin polymer. (Step 202). A polyurethane adhesive is applied onto the protective film 114 by a coating device 222 such as a die, wire bar or gravure often used in the prior art (step 204).

  The polyurethane adhesive used in this example is water-based or oil-based, and the applied thickness is about 0.5 μm. When the polyurethane adhesive is aqueous, the solvent is water, and when the polyurethane adhesive is oily, the solvent contains at least one selected from the group consisting of acetone, methyl ethyl ketone, and tetrahydrofuran.

  Thereafter, the protective film 114 of polyurethane adhesive is baked at a temperature of 30 to 55 ° C. by a baking device 226 such as a baking furnace (step 206). At this time, the baking temperature is about 45 ° C. and the baking time is about 1 minute. The length of the firing furnace is preferably only 3 to 5 m. Finally, the fired protective film and the polarizing film are heat-pressed at a temperature of 110 to 150 ° C. by the heating roller 224, and the temperature at this time is preferably about 120 ° C. Then, a polarizing plate 116 is obtained.

  As can be seen from the examples of the present invention, the firing time is reduced from the conventional 20 minutes to 1 minute, and the length of the firing furnace can be shortened from 50 m to 3 to 5 m. Therefore, when the polarizing plate is adhered using the present invention, the baking time is shortened, and the quality is prevented from being lost by baking for a long time. Next, in order to shorten the process time of the polarizing plate, the present invention not only can improve the production efficiency and yield of the polarizing plate, but also reduce the equipment cost of the adhesive device and reduce the equipment space required for it. You can also.

  In the present invention, preferred embodiments have been disclosed as described above, but these are not intended to limit the present invention in any way, and anyone who is familiar with the technology can make various modifications within the scope and spirit of the present invention. Fluctuations and hydration can be added. Therefore, the scope of protection of the present invention is based on the contents specified in the claims.

It is the schematic which shows the flow of the manufacturing method of the polarizing plate of a prior art. It is the schematic which shows the adhesion apparatus of the polarizing plate of a prior art. It is the schematic which shows the flow of the manufacturing method of the polarizing plate by one Example of this invention. It is a figure which shows the adhesion apparatus of the polarizing plate by one Example of this invention. It is a figure which shows the adhesion method of the polarizing plate by another prior art.

Explanation of symbols

  112 polarizing film, 114 protective film, 116 polarizing plate, 202, 204, 206, 208 steps, 222 coating device, 224 heating roller, 226 baking device

Claims (4)

A method for producing a polarizing plate comprising a polarizing film and a protective film,
Applying a polyurethane adhesive on the protective film;
Firing the protective film coated with the polyurethane adhesive;
Heating and pressure-bonding the polarizing film to the fired protective film;
The manufacturing method of the polarizing plate characterized by including.   The coating apparatus for applying the polyurethane adhesive is selected from the group consisting of a die, a wire bar, and a gravure, and the protective film and the polarizing film are subjected to a thermocompression bonding step with a heating roller. 1. A method for producing a polarizing plate according to 1.   The material of the polarizing film is polyvinyl alcohol, the material of the protective film is any one of triacetyl cellulose, a cyclic olefin copolymer and a cyclic olefin polymer, and the polyurethane adhesive is water-based 2. The method for producing a polarizing plate according to claim 1, wherein the solvent is water, and the solvent when the polyurethane adhesive is oily contains at least one selected from the group consisting of acetone, methyl ethyl ketone, and tetrahydrofuran. . A polarizing plate adhesive device comprising a polarizing film and a protective film,
An applicator for applying a polyurethane adhesive on the protective film, one selected from the group consisting of a die, a wire bar and a gravure;
A baking apparatus for baking the protective film coated with the polyurethane adhesive;
A heating roller for thermocompression bonding the polarizing film to the fired protective film;
A polarizing plate pressure-sensitive adhesive device comprising:

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