KR20090028445A - A process for producing a polarizer - Google Patents

Abstract

A manufacturing method of a polarizer suppressing the defect of the polarizer is provided to obtain the polarizer of specific characteristic according to the usage by laminating Polaroid film consisting of the polyvinyl alcohol type resin. A acetyl cellulose resin film(2) is laminated on one side of a polarizing film(1) consisting of a polyvinyl alcohol system resin through an adhesive layer. A cycloolefin system resin film(3) is laminated in the other side of the polaroid film through the glue layer. The celluloseacetate resin film and cycloolefin resin film are maintained over 8 weight%. The moisture regain of the Polaroid film before being laminated is maintained over 8 weight%. The tension after being laminated is less than 600 N/m. The Polaroid film, the celluloseacetate class resin film and cycloolefin group resin film are returned to the sending direction(A).

Description

A process for producing a polarizer

The present invention is a method of manufacturing a polarizing plate by laminating a cellulose acetate-based resin film on one side of a polarizing film made of polyvinyl alcohol-based resin through an adhesive layer and a cycloolefin-based resin film on the other side via an adhesive layer. It is about.

A polarizing plate is the structure which laminated | stacked the protective film on the single side | surface or both surfaces of the polarizing film formed from the polyvinyl alcohol-type resin in which the dichroic dye was adsorption-oriented normally through an adhesive bond layer. A polarizing plate is a component part of a liquid crystal display device, and is bonded by an adhesive to a liquid crystal cell through another optical film as needed.

Various configurations are required for the polarizing plate in accordance with the characteristics of the liquid crystal display device, and a protective film or an optical film disposed on the liquid crystal cell side is usually required for retardation characteristics, and a protective film disposed on the opposite side with the polarizing film interposed therebetween. Or an optical film requires surface characteristics, such as glare (light shining on a mirror surface), hard coat property, anti-glare (antiglare) property, antireflection property, etc. according to a use.

In Japanese Patent Laid-Open No. 2005-208456 (Patent Document 1), a cycloolefin-based resin film is laminated on one side of a polarizing film made of polyvinyl alcohol-based resin through an adhesive layer, and on the other side via an adhesive layer. When the cellulose acetate-based resin film is laminated, the cycloolefin-based resin film, which is relatively easy to impart retardation characteristics, and the cellulose acetate-based resin film, which is relatively easy to impart surface properties, are arranged one by one, so that it is possible to meet various needs. What is widely applicable is described.

Furthermore, Japanese Patent Laid-Open No. 2006-106016 (Patent Document 2) discloses a cycloolefin-based resin (norbornene-based resin) film on one side of a polarizing film made of polyvinyl alcohol-based resin, and a cellulose acetate-based on the other side. The resin (triacetyl cellulose) film was laminated | stacked through the adhesive agent which consists of aqueous solutions of polyvinyl alcohol-type resin, respectively, and the example which produced the polarizing plate is shown.

Further, in JP 2006-313205 A (Patent Document 3), in the manufacture of a polarizing plate, in a state where a laminated film of a polarizing film and a protective film is applied with a tension of 60 N / m to 450 N / m, By heat-processing on the conditions of 60 degreeC-120 degreeC of heating temperature, when it is left to the environment under high temperature and high humidity, polarization canceling phenomenon resulting from the shrinkage of a polarizing plate and the shift of the axial angle by expansion stress can be prevented. Is disclosed.

However, the polarizing plate in which the cycloolefin resin film is laminated | stacked on one side of the polarizing film which consists of polyvinyl alcohol-type resin through an adhesive bond layer, and the cellulose acetate type resin film is laminated | stacked on the other side through an adhesive bond layer is different from resin. Since the polarizing film was sandwiched by the protective film which consists of two layers, the polarizing plate tended to have a problem due to the difference in physical properties, thermal properties, mechanical properties, and the like. For example, after sandwiching a polarizing film with a protective film, there existed a problem that a recessed defect generate | occur | produced in a polarizing plate.

When the light of the fluorescent lamp is reflected inside the polarizer in the room and the reflection image is visually observed, the contour of the fluorescent lamp is clearly visible without distortion in the polarizer having no defects, whereas the reflective image of the fluorescent lamp is used in the polarizing plate having the concave defect as described above. It looks distorted. When such a defective polarizing plate is applied to a liquid crystal display device, the image is distorted at the defective portion. Therefore, when cut | disconnecting to a product size according to the magnitude | size of the liquid crystal display device applied from the polarizing plate wound by roll shape, the part containing a defect is removed as a defective article. For this reason, it is important to reduce the occurrence of such defects in polarizing plate production.

This invention is made | formed in order to solve the said subject, The objective is the cycloolefin resin film laminated | stacked on one side of the polarizing film which consists of polyvinyl alcohol-type resin through an adhesive bond layer, and the adhesive layer on the other side It is a method of manufacturing the polarizing plate in which a cellulose acetate type resin film is laminated | stacked through this, It is providing the method which can suppress defect generation of a polarizing plate.

The present invention is a method of manufacturing a polarizing plate by laminating a cellulose acetate-based resin film on one side of a polarizing film made of polyvinyl alcohol-based resin through an adhesive layer and a cycloolefin-based resin film on the other side via an adhesive layer. Tension after laminating the cellulose acetate-based resin film and the cycloolefin-based resin film on the polarizing film while maintaining the water content of the polarizing film immediately before the cellulose acetate-based resin film and the cycloolefin resin film were laminated. It is characterized in that below 600 N / m.

Here, it is preferable to keep the moisture content of the polarizing film immediately before laminating a cellulose acetate type resin film and a cycloolefin resin film at 8 weight% or more and 12 weight% or less.

Moreover, in the manufacturing method of the polarizing plate of this invention, after laminating | stacking a cellulose acetate type resin film and a cycloolefin resin film on a polarizing film, it is preferable to dry, maintaining tension at 600 N / m or less.

According to the present invention, since different types of resin films are laminated on both surfaces of the polarizing film made of polyvinyl alcohol-based resin, the polarizing plate on which the protective film made of the same resin is laminated on both sides is required depending on the use. It is a polarizing plate which can provide various characteristics, and can manufacture industrially advantageously the polarizing plate with few defects.

The manufacturing method of the polarizing plate of this invention laminates a cellulose acetate type resin film on one side of the polarizing film which consists of polyvinyl alcohol-type resin through an adhesive bond layer, and cycloolefin type resin film was laminated | stacked on the other side through an adhesive bond layer, It is assumed that it is a manufacturing method.

Polyvinyl alcohol-type resin which comprises the polarizing film used for the manufacturing method of this invention is obtained by saponifying polyvinyl acetate type resin. As polyvinyl acetate type resin, the copolymer etc. of vinyl acetate and the other monomer copolymerizable with this besides polyvinyl acetate which is a homopolymer of vinyl acetate are illustrated. As another monomer copolymerized with vinyl acetate, unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ether, acrylamide which has an ammonium group, etc. are mentioned, for example. The saponification degree of the polyvinyl alcohol-based resin is usually 85 mol% to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be further modified. For example, a polyvinyl polymer modified with aldehydes, polyvinyl acetal, or the like can also be used. Moreover, the average degree of polymerization of the polyvinyl alcohol-type resin which comprises a polarizing film is 1000-10000 normally, Preferably it is 1500-5000.

What formed such a polyvinyl alcohol-type resin into a film form (polyvinyl alcohol-type resin film) is used as a raw film of a polarizing film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. Although the film thickness of a polyvinyl alcohol-type resin film is not specifically limited, For example, they are 10 micrometers-150 micrometers.

The polarizing film is usually a step of uniaxially stretching such a polyvinyl alcohol-based resin film, a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye, and a polyvinyl alcohol on which the dichroic dye is adsorbed. It manufactures through the process of processing a system resin film with aqueous boric acid solution, and the process of washing with water after the process by this boric acid aqueous solution.

Uniaxial stretching may be performed before dyeing, may be performed simultaneously with dyeing, or may be performed after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or may be performed during boric acid treatment. Of course, it is also possible to uniaxially stretch in these several steps. In uniaxial stretching, you may extend | stretch to 1 axis between rolls from which a circumferential speed differs, and you may extend | stretch to 1 axis using a heat roller. Moreover, dry stretching, such as extending | stretching in air, may be sufficient, and wet extending | stretching may be sufficient as extending | stretching in the state swollen with a solvent. The draw ratio is usually 3 to 8 times.

In order to dye a polyvinyl alcohol-type resin film with a dichroic dye, what is necessary is just to immerse a polyvinyl alcohol-type resin film in the aqueous solution containing a dichroic dye, for example. Specifically, iodine and a dichroic dye are used as the dichroic dye. Moreover, it is preferable to perform the immersion process in water before a polyvinyl alcohol-type resin film.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing iodine and potassium iodide is employ | adopted normally. The content of iodine in this aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually 20 ° C to 40 ° C, and the immersion time (dyeing time) in the aqueous solution is usually 20 to 1800 seconds.

On the other hand, when using a dichroic dye as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing water-soluble dichroic dye is employ | adopted normally. The content of the dichroic dye in this aqueous solution is usually 1 × 10 ^-4 to 10 parts by weight, preferably 1 × 10 ^{-3 to} 1 part by weight, per 100 parts by weight of water. This aqueous solution may contain inorganic salts, such as sodium sulfate, as a dyeing adjuvant. The temperature of the dye aqueous solution used for dyeing is 20 degreeC-80 degreeC normally, and the immersion time (dyeing time) in this aqueous solution is 10 to 1800 second normally.

The boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed polyvinyl alcohol-type resin film in boric acid containing aqueous solution. The amount of boric acid in boric acid containing aqueous solution is 2-15 weight part normally per 100 weight part of water, Preferably it is 5-12 weight part. When using iodine as a dichroic dye, it is preferable that this boric acid containing aqueous solution contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. Immersion time in boric acid containing aqueous solution is 60-1200 second normally, Preferably it is 150-600 second, More preferably, it is 200-400 second. The temperature of the boric acid containing aqueous solution is 50 degreeC or more normally, Preferably it is 50 degreeC-85 degreeC, More preferably, it is 60 degreeC-80 degreeC.

The polyvinyl alcohol-based resin film after boric acid treatment is usually washed with water. A water washing process is performed by immersing the polyvinyl alcohol-type resin film which processed boric acid in water, for example. The temperature of water in a water washing process is 5 degreeC-40 degreeC normally, and immersion time is 1-120 second normally. After water washing, a drying process is performed and a polarizing film can be obtained. A drying process is normally performed using a hot air dryer and a far infrared heater. The temperature of a drying process is 30 degreeC-100 degreeC normally, Preferably it is 50 degreeC-80 degreeC. The drying treatment time is usually 60 to 600 seconds, and preferably 120 to 600 seconds.

In this way, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment to obtain a polarizing film. The thickness of this polarizing film is normally in the range of 5 micrometers-40 micrometers, Preferably it exists in the range of 10 micrometers-35 micrometers. In the manufacturing method of the polarizing plate of this invention, a cellulose acetate type resin film is laminated on one side of the polarizing film which consists of polyvinyl alcohol-type resin through an adhesive bond layer, and a cycloolefin type resin film is laminated on the other side via an adhesive bond layer, and a polarizing plate To prepare.

The cycloolefin resin film used in the production method of the present invention is also a thermoplastic resin (a thermoplastic cycloolefin resin) having a unit of a monomer made of a cyclic olefin (cycloolefin) such as norbornene and a polycyclic norbornene monomer. Called) film. In the present invention, the cycloolefin resin may be a hydrogenated product of the ring-opening polymer of the cycloolefin or the ring-opening copolymer using two or more cycloolefins, and an addition polymer of an aromatic compound having a cycloolefin, a chain olefin, a vinyl group, or the like. You may. It is also effective to introduce a polar group.

In the case of using a copolymer of a cycloolefin with a linear olefin or an aromatic compound having a vinyl group, examples of the linear olefin include ethylene and propylene, and examples of the aromatic compound having a vinyl group include styrene, α-methylstyrene, and nuclear alkyl substitution. Styrene and the like. In such a copolymer, 50 mol% or less (preferably 15 mol%-50 mol%) of the monomer unit which consists of cycloolefin may be sufficient. When using the ternary copolymer of a cycloolefin, a linear olefin, and the aromatic compound which has a vinyl group especially, the unit of the monomer which consists of cycloolefin can be made into a comparatively small quantity as mentioned above. In such a terpolymer, the unit of the monomer which consists of linear olefins is 5 mol%-80 mol% normally, and the unit of the monomer which consists of aromatic compounds which have a vinyl group is 5 mol%-80 mol% normally.

Cycloolefin resins are suitable commercially available products such as Topas (manufactured by Ticona), Aton (manufactured by JSR Co., Ltd.), ZEONOR (manufactured by Nihon Zeon Co., Ltd.), ZEONEX (Nihon Xeon Co., Ltd.) Agent), Apel (made by Mitsui Chemical Co., Ltd.), etc. can be used suitably. When forming a cycloolefin resin into a film and forming into a film, well-known methods, such as the solvent casting method and the melt-extrusion method, are used suitably. Furthermore, for example, the cycloolefin resin film previously formed into a film, such as Essina (made by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), Zeanoa film (manufactured by OPTES), etc. You may use a commercial item.

The cycloolefin resin film may be uniaxially stretched or biaxially stretched. By extending | stretching, arbitrary phase difference values can be provided to a cycloolefin resin film. Stretching is normally performed continuously while unwinding a film roll, and it extends | stretches in the advancing direction of the roll, the advancing direction and the perpendicular direction, or both as a heating furnace. As for the temperature of a heating furnace, the range of glass transition temperature +100 degreeC is employ | adopted normally in the glass transition temperature vicinity of cycloolefin resin. The magnification of stretching is usually 1.1 to 6 times, preferably 1.1 to 3.5 times.

When a cycloolefin resin film exists in roll state, since there exists a tendency for films to adhere | attach and it is easy to generate | occur | produce blocking, it usually bonds a protective film and becomes roll winding. Moreover, since cycloolefin resin film is generally inferior in surface activity, it is preferable to perform surface treatment, such as a plasma treatment, a corona treatment, an ultraviolet irradiation treatment, a flame (flame) treatment, and saponification treatment, to the surface to adhere | attach with a polarizing film. . Especially, the plasma process and corona treatment which can be implemented comparatively easily are suitable.

Further, the cellulose acetate-based resin film used in the production method of the present invention may be, for example, a triacetyl cellulose film, a diacetyl cellulose film, a cellulose acetate propionate film, or the like as a film of a partial or complete acetate ester of cellulose. . As such a cellulose acetate-based resin film, a suitable commercial item, for example, Fujitech TD80 (manufactured by Fuji Photo Film Co., Ltd.), Fujitech TD80UF (manufactured by Fuji Photo Film Co., Ltd.), Fujitech TD80UZ (manufactured by Fuji Photo Film Co., Ltd.) ), KC8UX2M (manufactured by Konica Minolta Opt Co., Ltd.), KC8UY (manufactured by Konica Minolta Opt Co., Ltd.), and the like can be suitably used. Cellulose acetate is also called acetyl cellulose, and also called cellulose acetate.

The surface of a cellulose acetate-based resin film may be subjected to surface treatment such as an antiglare treatment, a hard coat treatment, an antistatic treatment, an antireflection treatment, and the like depending on the use. Moreover, arbitrary phase difference values can be given also to a cellulose acetate type resin film by extending | stretching.

When a cellulose acetate-based resin film also exists in a roll state, since a film tends to adhere | attach and block easily, it usually gives a concave-convex process to a roll edge part, or inserts a ribbon to an edge part, and roll-winds. In addition, in order to improve adhesiveness with a polarizing film, this cellulose acetate type resin film is usually saponified. As a saponification process, the method of immersing in aqueous solution of alkalis, such as sodium hydroxide and potassium hydroxide, can be employ | adopted.

The thickness of the cycloolefin-based resin film and the cellulose acetate-based resin film used in the production method of the present invention is preferably thinner. However, when too thin, the strength is lowered and the workability is inferior. Problems such as a decrease or a large weight of the polarizing plate occur. Therefore, the suitable thickness of these films is 5 micrometers-200 micrometers normally, Preferably they are 10 micrometers-150 micrometers, More preferably, they are 20 micrometers-100 micrometers.

In the manufacturing method of this invention, the adhesive agent used for adhesion | attachment of a polarizing film and a cycloolefin resin film, and the adhesive agent used for adhesion | attachment of a polarizing film and a cellulose acetate-based resin film are made with a cycloolefin resin film and a cellulose acetate-based resin film. In consideration of the adhesiveness, different kinds may be used. However, in consideration of ease of construction and the like, when both the cycloolefin-based resin film and the cellulose acetate-based resin film adhere to the polarizing film, it is advantageous to use the same adhesive on both sides.

From the standpoint of thinning the adhesive layer, the adhesive is preferably an aqueous system, that is, an adhesive component dissolved in water or dispersed in water. For example, a polyvinyl alcohol-based resin, a urethane resin, or the like is used as a main component, and in order to improve adhesiveness, it is common to use a composition in which an isocyanate compound, an epoxy compound, and the like are blended. In the case where such an aqueous adhesive is used, the thickness of the adhesive layer is usually 1 m or less, and even if the cross section is observed with a normal optical microscope, the adhesive layer is virtually not observed.

When using polyvinyl alcohol-based resin as the main component of the adhesive, in addition to partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, amino group-modified polyvinyl alcohol Modified polyvinyl alcohol-based resins such as vinyl alcohol may be used. When using such polyvinyl alcohol-type resin, the aqueous solution of polyvinyl alcohol-type resin is used as an adhesive agent. The concentration of the polyvinyl alcohol-based resin in the adhesive is usually 1 to 10 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of water.

An epoxy compound etc. can be mix | blended with the adhesive agent which consists of aqueous solution of polyvinyl alcohol-type resin in order to improve adhesiveness as mentioned above. The epoxy compound is, for example, a water-soluble poly that is obtained by reacting epichlorohydrin with a polyamide polyamine obtained by a reaction of a polyalkylene polyamine such as diethylenetriamine, triethylenetetramine, and dicarboxylic acid such as adipic acid. Amide epoxy resins can be used. Commercially available products of such polyamide epoxy resins include Sumirez Resin 650 (manufactured by Sumica Chemtex Co., Ltd.), Sumirez Resin 675 (manufactured by Sumica Chemtex Co., Ltd.), WS-525 (manufactured by Nippon PMC Co., Ltd.), and the like. Can be mentioned. When mix | blending an epoxy compound, the addition amount is 1-100 weight part normally with respect to 100 weight part of polyvinyl alcohol-type resins, Preferably it is 1-50 weight part.

Here, FIG. 1 is a perspective view which shows typically the lamination | stacking of the polarizing film in the manufacturing method of the polarizing plate of this invention, a cellulose acetate type resin film, and a cycloolefin type resin film. In the manufacturing method of the polarizing plate of this invention, as shown in FIG. 1, after apply | coating an adhesive agent, the cellulose acetate type resin film 2 is made to one side of the polarizing film 1 which consists of polyvinyl alcohol-type resin through an adhesive bond layer. The cycloolefin resin film 3 is laminated on the other side via an adhesive layer, and is bonded to each other with nip rolls 5a and 5b to produce a polarizing plate 4. In addition, this lamination can be performed continuously, conveying a polarizing film 1, a cellulose acetate resin film 2, and a cycloolefin resin film 3 in a conveyance direction A as shown in FIG. .

The coating method of an adhesive agent is generally known generally, and one or both adhesives are formed by, for example, a casting method, a Meyer method, a bar coating method, a gravure coating method, a die coating method, a dip coating method, a spraying method, or the like. The method of apply | coating between the adhesive surface of a film or two films which should be adhere | attached is mentioned. A casting method is a method of flowing and spreading an adhesive agent on the surface while moving the polarizing film or protective film which is a to-be-coated object in the substantially vertical direction, the substantially horizontal direction, or the oblique direction between them.

The manufacturing method of the polarizing plate of this invention maintains the moisture content of the polarizing film 1 immediately before laminated | stacking the cellulose acetate type resin film 2 and the cycloolefin resin film 3 at 8 weight% or more. do. When the moisture content of the polarizing film 1 immediately before the said lamination | stacking is less than 8 weight%, a concave defect arises easily in the obtained polarizing plate 4. This is considered to be for the following reason. That is, when it is estimated that the distortion which generate | occur | produces when a film contacts a roll remains and is present, when a concave defect is low, when the moisture content of the polarizing film 1 is low, a polarizing film will become too hard and the distortion which generate | occur | produced As a result of this not being easily alleviated, it is considered that concave defects are likely to remain. On the other hand, when the moisture content of the polarizing film 1 just before lamination | stacking is too high, drying of the polarizing film 1 is inadequate, the polarizing film 1 will shrink | contract by drying after protective film lamination | stacking, and the obtained polarizing plate There exists a tendency for the defect which a stain produces to (4) tends to generate | occur | produce. For this reason, it is preferable that the said moisture content is 20 weight% or less. Furthermore, it is preferable that the said moisture content exists in the range of 8 weight%-12 weight%.

The moisture content is, for example, drying the polarizing film 1 immediately before lamination of the cellulose acetate-based resin film 2 and the cycloolefin-based resin film 3 in an oven at 105 ° C for 1 hour, It can calculate from the weight before and behind that.

Moisture content = [1- (weight after drying) / (weight before drying)] × 100 (%)

In addition, in order to maintain the moisture content of the polarizing film 1 immediately before the cellulose acetate type resin film 2 and the cycloolefin resin film 3 are laminated | stacked at 8 weight% or more, it wash | cleans specifically as mentioned above. What is necessary is just to adjust the temperature and time at the time of drying the polyvinyl alcohol-type resin film afterwards suitably. Specifically, if there is only one drying furnace, the moisture content of the polarizing film 1 can be adjusted by appropriately adjusting the temperature and residence time in a drying furnace. Moreover, the method of installing two drying furnaces in two or more stages, and adjusting the temperature of each drying furnace and the residence time in each drying furnace is also effective.

Moreover, the manufacturing method of the polarizing plate of this invention is one of the characteristics that the tension after laminating the cellulose acetate type resin film 2 and the cycloolefin resin film 3 on the polarizing film 1 is 600 N / m or less. do. When the said tension exceeds 600 N / m, the defect which becomes concave in the obtained polarizing plate will generate | occur | produce easily. This assumes that the larger the tension, the greater the distortion generated when the film contacts the roll. On the other hand, when the said tension is too low, since the wrinkles easily arise in the obtained polarizing plate, it is preferable that the said tension is 100 N / m or more. Furthermore, it is further more preferable that the said tension exists in the range of 300 N / m-500 N / m. The tension after laminating the cellulose acetate-based resin film 2 and the cycloolefin-based resin film 3 on the polarizing film 1 is, for example, as shown in FIG. It can adjust by the tension force between 5b) and the other nip roll (not shown) provided downstream.

In the manufacturing method of the polarizing plate of this invention, after laminating the cellulose acetate-type resin film 2 on one side of the polarizing film 1, and the cycloolefin resin film 3 on the other side, as mentioned above, tension is applied. It is preferable to perform a drying process, keeping at 600 N / m or less. As described above, the tension generated in the laminated film can be adjusted by the tensile force between the nip rolls 5a and 5b for insertion shown in FIG. 1 and other nip rolls (not shown) provided on the downstream side. Since the downstream nip rolls are often provided on the downstream side of the drying furnace (for example, near the exit of the drying furnace), it is preferable to perform the drying treatment while maintaining the tension immediately after laminating the protective film. Therefore, it is preferable that the said tension at the time of a drying process also exists in the range of 100 N / m-600 N / m and further 300 N / m-500 N / m like the tension immediately after protective film lamination.

Although drying process is performed by blowing hot air, for example, the temperature at that time is normally selected suitably in the range of 40 degreeC-100 degreeC, Preferably it is 60 degreeC-100 degreeC. The drying time is usually 20 to 1200 seconds. After drying, it is also preferable to cure for 12 to 600 hours at a temperature of room temperature (20 ° C) or slightly higher, for example, 20 ° C to 50 ° C. The temperature at the time of curing is generally set lower than the temperature employed at the time of drying.

Thus, in the polarizing plate obtained by the manufacturing method of this invention, an adhesive layer is normally formed in the one side or both sides. In the case where the pressure-sensitive adhesive layer is provided only on one side, either the side on which the cycloolefin-based resin film is laminated or the side on which the cellulose acetate-based resin film is laminated may be used, but when applying this polarizing plate to a liquid crystal display device, Since the side where the pin type resin film is laminated is often directed to the liquid crystal cell, it is common to form an adhesive layer on the side where the cycloolefin resin film is laminated. The thickness of an adhesive layer is 5 micrometers-100 micrometers normally, Preferably they are 5 micrometers-40 micrometers. If the pressure-sensitive adhesive layer is too thin, the adhesiveness is lowered, and if the pressure-sensitive adhesive layer is too thick, problems such as sticking out of the pressure-sensitive adhesive tend to occur.

The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is usually made of acrylic resin, styrene resin, silicone resin and the like as a base resin, crosslinking agent selected from isocyanate compound, epoxy compound, aziridine compound and the like, furthermore a silane coupling agent. The composition is added.

The surface of the formed adhesive layer is normally protected by the separator film to which the mold release process was performed. The separator film is peeled off before bonding the polarizing plate to a liquid crystal cell or the like.

The polarizing plate with a pressure-sensitive adhesive layer usually has a shape of a roll material having a large shape and a sheet material, and is cut (chip cut) by a cutting tool having a sharp blade in order to obtain a polarizing plate having a desired shape and a transmission axis. For this reason, in the polarizing plate chip obtained by cutting | disconnecting, the state by which the polarizing film was exposed to the outside in the outer peripheral part will arise. When the polarizing plate chip in this state is subjected to durability tests, such as a heat shock test, for example, compared with the polarizing plate generally used (for example, the polarizing plate which laminated | stacked the cellulose acetate-based resin film on both surfaces of a polarizing film), the problem of peeling, a crack, etc. This tends to occur. For this reason, it is more preferable to cut the outer peripheral end part continuously by the fly cut method etc. in the polarizing plate chip of the polarizing plate obtained by the manufacturing method of this invention.

Although an Example is given to the following and this invention is demonstrated in more detail, this invention is not limited to these Experimental examples. In the examples,% indicating the content is based on weight unless otherwise specified.

Experimental Example 1

A polyvinyl alcohol film having a thickness of 75 µm with an average degree of polymerization of about 2400 and a degree of saponification of 99.9 mol% or more, while being swelled by immersion in pure water at 30 ° C while being swelled, to a draw ratio of 1.3 times. It extended in the longitudinal direction. Dyeing this polyvinyl alcohol film with the aqueous solution (iodine: potassium iodide: water = 0.05: 2: 100 (weight ratio)) containing 30 degreeC iodine and potassium iodide, maintaining the said draw ratio, Then, after extending | stretching so that it may become a total magnification of 5.6 times, carrying out crosslinking process by the aqueous solution containing potassium iodide and boric acid at 54 degreeC (potassium iodide: boric acid: water = 12: 5: 100 (weight ratio)), 12 It was washed with pure water at ℃. The polyvinyl alcohol film after washing is passed through this drying furnace in which the temperature is maintained at 65 ° C., 75 ° C. and 85 ° C. in this order, dried under the condition that the total residence time is 169 seconds, and iodine is adsorbed onto polyvinyl alcohol. Samples 1 to 5 of the oriented polarizing film were obtained. It was 5% when the obtained samples 1-5 were dried in 105 degreeC oven for 1 hour, and the moisture content was computed from the weight before and after that by the following formula.

Moisture content = [1- (weight after drying) / (weight before drying)] × 100 (%)

Separately, in 100 parts by weight of water, 3 parts by weight of carboxyl group-modified polyvinyl alcohol (Kurare foam KL318 (Kuraray Co., Ltd.)), and a water-soluble polyamide epoxy resin (Sumirez resin 650 (made by Sumika ChemteX Co., Ltd.)) (Aqueous solution having a solid content concentration of 30%) 1.5 parts by weight were dissolved to prepare an aqueous adhesive containing polyvinyl alcohol-based resin as a main component.

Norbornene-based resin film (zeonoa film (manufactured by Optes), thickness: 80 µm) previously subjected to corona treatment on one side of samples 1 to 5 of the polarizing film in advance, and on the other side Triacetyl cellulose film (KC8UX2M (manufactured by Konica Minolta Opto Co., Ltd., thickness: 80 µm)) subjected to saponification treatment was laminated through the adhesive as shown in FIG. 1, and bonded by a nip roll. At this time, the nip roll for joining and the nip roll downstream (in this example, provided near the exit of a drying furnace) were adjusted suitably, and the tension after lamination | stacking of the samples 1-5 was changed. It dried for 5 minutes at 80 degreeC, maintaining each tension, and obtained samples 1-5 of polarizing plates.

On the other hand, using three drying furnaces in which the temperature at the first stage is 50 ° C, the temperature at the second stage at 65 ° C, and the temperature at the third stage, respectively, is maintained at 85 ° C. Sample 7, and total residence time, of the polarizing film having a moisture content of 9.1% were dried under the same conditions as Sample 6 except that the temperature was set to 60 ° C by drying the samples 6 and 2nd stage of the polarizing film with 7.9%. Sample 8 of a polarizing film which dried on the same conditions as sample 7 and made moisture content 9.5% except having made it to 162 second was produced similarly to the samples 1-5 mentioned above, and laminated | stacked all about these samples 6-8. The following tension was maintained at 448 N / m, and the samples 6-8 of the polarizing plate were similarly produced.

When preparing samples 1 to 8 of the polarizing plate, the inspector visually observed the polarizing plate coming out of the drying furnace and judged the presence or absence of concave defects by whether or not distortion was observed on the reflection of the illumination fluorescent lamp shining on the surface of the polarizing plate. As described above, the reflection image of the fluorescent lamp is distorted and observed where there is a concave defect. And the refresh rate of the defect was determined by how many concave defects observed as mentioned above per 100 m of flow direction lengths of the polarizing plate produced on the line. The results are shown in Table 1 as the number of defects per 100 m length (pieces / 100 m).

Moisture content (%) Tension (N / m) Number of concave defects (pcs / 100m) Remarks Sample 1 5 821 > 100 compare Sample 2 5 672 > 100 compare Sample 3 5 597 50-100 compare Sample 4 5 522 25-50 compare Sample 5 5 448 10 compare Sample 6 7.9 448 1-10 compare Sample 7 9.1 448 <1 Invention Sample 8 9.5 448 <1 Invention

As can be seen from Table 1, the concave defect could be reduced by lowering the tension while keeping the moisture content of the polarizing film at 5%, but even if the tension was lowered to 448 N / m, the polarizing plate per 100 m in length. About ten concave defects were observed (sample 5). On the other hand, if the moisture content of the polarizing film is changed while the tension is kept at 448 N / m, almost no defects that become concave are observed when the moisture content is 8% or more (9.1% or 9.5%) specified in the present invention. (Samples 7 and 8).

The disclosed embodiments and examples are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown by above-described not description but Claim, and it is intended that the meaning of a claim and equality and all the changes within a range are included.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows typically the lamination | stacking of the polarizing film, the cellulose acetate type resin film, and the cycloolefin resin film in the manufacturing method of the polarizing plate of this invention.

<Description of the code>

1: polarizing film

2: cellulose acetate resin film

3: cycloolefin resin film

4: polarizer

5a, 5b: nip rolls.

Claims (3)

A method of manufacturing a polarizing plate by laminating a cellulose acetate-based resin film on one side of a polarizing film made of polyvinyl alcohol-based resin through an adhesive layer and a cycloolefin-based resin film on the other side via an adhesive layer. The moisture content of the polarizing film immediately before laminating the cellulose acetate-based resin film and the cycloolefin resin film was maintained at 8% by weight or more, and the tension after laminating the cellulose acetate-based resin film and the cycloolefin resin film on the polarizing film The manufacturing method of the polarizing plate set to 600 N / m or less. The method for producing a polarizing plate according to claim 1, wherein the moisture content of the polarizing film immediately before the cellulose acetate-based resin film and the cycloolefin-based resin film is laminated is maintained at 8 wt% or more and 12 wt% or less. The method for producing a polarizing plate according to claim 1 or 2, wherein the cellulose acetate-based resin film and the cycloolefin-based resin film are laminated on the polarizing film, followed by drying while maintaining the tension at 600 N / m or less.

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