JP2009015273A - Production of polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polarizing plate having reduced defects in the appearance. <P>SOLUTION: In the method for producing a polarizing plate, at least composed of a polarizer and a resin film, prior to the polarizer and the resin film being pasted, the resin film is subjected to heat treatment. Since the heat treatment is performed at least to the resin film before the polarizer and the resin film are pasted, the production of a polarizing plate of high quality free, from deficiency in appearance or the like, is made possible, and it is particularly optimum as a method for producing a polarizing plate used for a big screen monitor, an LCD (liquid crystal display) for a television or the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique in which heat treatment is performed immediately before a protective film or the like is bonded to both surfaces of a polarizer in manufacturing a polarizing plate with an adhesive.

Conventionally, various means are used for the heating method used for resin films and the like. For example,
(1) A method in which a cartridge-type heater is installed in the heat roll body and the heating roll is heated.
(2) A method in which a sheathed heater is installed in the heating roll body and the heating roll is heated.
There are also disclosures of various more devised techniques such as JP-A-3-071811.
Japanese Patent Laid-Open No. 3-071811

  However, in the above method, there is a drawback that it is difficult to maintain a constant temperature on the roller surface in the main body of the heating roll due to the ON or OFE state of the temperature controller, and it is not possible to maintain a variation in the set heating temperature. There was a limit in the manufacturing process that should not be.

  In other words, the present inventors studied not only a conventional film heat treatment method, but a solution for eliminating appearance loss when bonding a protective film or the like on both sides of a polarizer during polarizing plate production. Was.

  If the resin film has slight appearance damage such as dents, nicks, ear extension, and ear clogging, the appearance loss such as curl, nick, and streak deformation may occur when the resin film is bonded to both sides of the polarizer. May occur, which has been one factor that deteriorates the yield of recent large LCD screens.

  If one of the causes of the appearance damage is saponification before the film adhesion process, blocking (appearance deformation accompanying adhesion marks), streak-like deformation, and nick may occur.

  As other causes of appearance damage, appearance damage such as blocking and depression generated when the film is stored for a long time in a roll state is a major factor.

  As a result, as a result of repeated ingenuity, researchers have used an adhesive for the polarizer and the resin film in the manufacture of a polarizing plate formed by laminating a polarizer and a resin film such as a protective film as a means for solving problems. The present inventors have found that the problem can be solved by adding a process of providing a heat treatment that gradually adds hot / cold heat controlled with precision temperature to the resin film and a cooling process that gradually cools the resin film immediately before bonding.

When the film is saponified before bonding, small hindrance factors, streak-like deformations, invisible blurring, and external deformation due to adhesion, etc., are caused by gradually heating the film surface. It was solved by gradually cooling later.

  Moreover, when the film was stored for a long time in a roll state, blocking, depression, and the like were generated, which was a major factor in the appearance loss layer.

  It is considered that the film having the above-mentioned appearance damage is restored by uniform heat treatment and cooling treatment.

  Based on the above, as a more detailed process means, a film obtained by iodine-staining polyvinyl alcohol resin (PVA) is continuously stretched and processed into a polarizer, and the obtained polarizer is subjected to both sides of the resin film or One side is subjected to thermal heat treatment with a far infrared heater and continuous heating roller, and immediately after that, the film is transported through a process of gradually cooling and heat treatment for cooling, and the polarizer and the resin film are immediately bonded. It is characterized by being bonded with an agent.

  In particular, far-infrared rays have a high absorption efficiency in the wavelength range of 3 to 1000 micrometers, and when they hit the film, they are absorbed and vibrate molecules and crystals and change to thermal energy. It is well known that molecular compounds well absorb infrared rays in the far-infrared wavelength region.

  Specifically, the resin film is a cellulose ester, but a film of COC (Cyclo-olefin Polymer) or COP (Cyclo-olefin Polymer) is also used as a laminated film.

  The heat treatment condition is that the film surface temperature is 50 ° C. to Tg (glass transition temperature) or less, more specifically 60 ° C. to 100 ° C., and the temperature is 70 ° C. to 90 ° C. Is optimal.

  In the heat treatment method, at least three or more far infrared heater panels are provided in the width direction, and each panel itself has a temperature control function.

  In the heat treatment method, at least three or more far infrared heater panels are provided in the longitudinal direction, and each panel itself has a temperature control function.

  Therefore, the far-infrared panel has nine or more faces in total.

  The heat treatment method is a heat roll method, and the number of rollers is close to 10 or more, and the film is gradually heated and cooled by a plurality of cooling rollers from a roller portion that reaches a certain heating temperature. It is characterized by a process in which films and the like are conveyed.

  The temperature-cooling heat treatment temperature control method is proportional control or PID (Proportional Integral Derivative) control.

  As a result, according to the present invention, as a result of using an apparatus that embodies an improved method such as appearance damage of the resin film, the appearance damage that has conventionally occurred on the polarizing plate can be greatly reduced, and the yield is improved.

  In the manufacture of the polarizing plate 6 comprising the polarizer 1 of FIG. 1 and the resin film 2 such as a protective film, at least the precision temperature is applied to the resin film immediately before the polarizer and the resin film are bonded using the adhesive 5. The best mode is to manufacture a polarizing plate through a heat treatment 3 step using a controlled far-infrared heater.

  The heating roller and the cooling roller in FIG. 2 are each arranged in 20 groups, the heating roller has a diameter of 10 to 15 cm, and is arranged as close to the roller as possible, and the cooling roller has a diameter of 9 to 15 cm. It is desirable to be as close as possible to the next roller.

  A heating roller group is installed on the roll-shaped resin film supply and conveyance side, a far-infrared panel heater is installed on the superheated roller group, then a cooling roller group is installed in the direction of conveyance, and cold air is blown above the cooling roll group The area of the heating roller group and the area of the cooling roller group are partitioned by a temperature-shielding partition curtain with a gap through which the resin film can be transported. The best mode is a method in which the temperature is sensed and the far-infrared heater panel and the heating / cooling temperature around the sensing point are appropriately controlled to the set temperature by the temperature controller.

Schematic configuration diagram used to implement the present invention

Schematic configuration diagram of heat treatment equipment

Explanation of symbols

1. 1. Polarizer 2. Resin film 3. Heat treatment apparatus 4. Roll crimping device Adhesive 6. Polarizing plate 7. Resin film roll8. Far infrared heater panel9. Temperature sensor 10. Heating roller county 11. Cooling roller county 12. 10. Temperature shielding partition curtain Cold air duct

Claims (17)

  In the production of a polarizing plate comprising at least a polarizer and a resin film, the production of the polarizing plate is characterized in that at least the resin film is subjected to hot and cold heat treatment immediately before bonding the polarizer and the resin film.   The manufacture of the polarizing plate according to claim 1, wherein the heat treatment and the bonding of the polarizer and the resin film are continuously performed.   Polyvinyl alcohol-based resin (PVA) is dyed and continuously stretched to be processed into the polarizer. After heating and cooling heat treatment on both sides or one side of the resin film, the polarizer and the resin are obtained. The production of the polarizing plate according to claim 1 or 2, wherein a film is bonded.   The polarizing plate according to claim 1, wherein the resin film is a cellulose ester.   The said resin film is COC (Cyclo-olefin Polymer) or COP (Cyclo-olefin Polymer), The manufacture of the polarizing plate in any one of Claims 1-4.   The condition of the heat treatment is that the film surface temperature is 50 ° C. to Tg (Glass transition temperature glass transition temperature) or less, The production of the polarizing plate according to claim 1.   The said heat processing means is a far infrared heater, Manufacture of the polarizing plate in any one of Claims 1-6.   The said heat processing means is a heat roll method, The manufacture of the polarizing plate in any one of Claims 1-7.   The production of the polarizing plate according to claim 1, wherein the number of rollers in the heat roll method is 10 or more.   The said heat processing means is a warm air spraying method, The manufacture of the polarizing plate in any one of Claims 1-9.   The manufacturing method of the polarizing plate according to claim 1, wherein the heat treatment means also includes a cooling means.   The manufacturing condition of the polarizing plate according to claim 11, wherein the cooling condition is a film surface temperature of 20 ° C. to 40 ° C. or less.   The polarizing plate production according to any one of claims 1 to 12, wherein the heat treatment temperature adjustment control method is proportional control or PID (Proportional Integral Derivative) control.   The production of the polarizing plate according to any one of claims 1 to 13, wherein the heat treatment rolls are arranged close to each other.   The manufacturing time of the polarizing plate according to any one of claims 1 to 14, wherein the heat treatment time is 1 second to 60 seconds.   The manufacturing method of the polarizing plate according to any one of claims 1 to 15, wherein the heating temperature is at least divided into two or three or more with respect to the lateral width surface of the resin film.   The manufacturing method of a polarizing plate according to any one of claims 1 to 16, wherein the heating temperature is at least divided into three or more with respect to the longitudinal direction surface of the resin film.

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