TWI432492B - A process for producing a polarizer - Google Patents

Description

Polarizing plate manufacturing method

In the present invention, a cellulose acetate-based resin film is laminated on one surface of a polarizing film composed of a polyvinyl alcohol-based resin, and a polarizing plate is formed by laminating a cycloolefin-based resin film on the other surface via an adhesive. The method.

The polarizing plate is usually formed by laminating a protective film on one surface or both surfaces of a polarizing film formed by adsorbing a dichroic dye and having an oriented polyvinyl alcohol-based resin. The polarizing plate is used as a component of the liquid crystal display device, and is attached to the liquid crystal cell with an adhesive via another optical film as needed.

The polarizing plate is required to have various configurations in accordance with the characteristics of the liquid crystal display device. Generally, a phase difference characteristic is required for the protective film or the optical film disposed on the liquid crystal cell side, and a protective film or optical film disposed on the opposite side to sandwich the polarizing film. The film is required to have surface characteristics such as antiglare property and antireflection depending on the application.

Japanese Patent Publication No. 2005-208456 (Patent Document 1) discloses that a cycloolefin-based resin film is laminated on one surface of a polarizing film composed of a polyvinyl alcohol-based resin via an adhesive layer, and the other surface is interposed therebetween. In the step of laminating the cellulose acetate-based resin film, the cycloolefin-based resin film which is easy to impart phase difference characteristics and the cellulose acetate-based resin film which is easy to impart surface properties are disposed on each single surface. Can meet a wide range of requirements.

In JP-A-2006-106016 (Patent Document 2), it is disclosed that an adhesive layer composed of an aqueous solution of a polyvinyl alcohol-based resin is laminated on one surface of a polarizing film composed of a polyvinyl alcohol-based resin. An example of producing a polarizing plate by laminating a film of a olefin-based resin (norbornene-based resin) with a film of a cellulose acetate-based resin (triethylene fluorene cellulose) on the other surface.

In JP-A-2006-313205 (Patent Document 3), it is disclosed that a laminated film of a polarizing film and a protective film is subjected to a tension of 60 to 450 N/m under a heating temperature when a polarizing plate is manufactured. When the heat treatment is carried out at 60 to 120 ° C, the depolarization phenomenon such as the axial angle shift caused by the contraction of the polarizing plate and the expansion stress in the environment of high temperature and high humidity can be prevented.

However, a polarizing plate obtained by laminating a layer of a cycloolefin-based resin film on one surface of a polarizing film composed of a polyvinyl alcohol-based resin and laminating a cellulose acetate-based resin film on the other surface via an adhesive layer is used. Since the polarizing film is sandwiched by the protective film composed of different resins, the polarizing plate tends to be in a bad state due to the difference in physical properties, thermal properties, mechanical properties, and the like of the respective protective films. For example, after the polarizing film is sandwiched by the protective film, there is a problem that a concave ridge is generated on the polarizing plate.

The light of the fluorescent lamp is reflected by the polarizing plate indoors, and the reflected image is observed by the naked eye, and the contour of the non-deformed fluorescent lamp can be clearly observed with respect to the innocent polarizing plate, such as the polarizing plate with the concave defect described above. A deformed fluorescent lamp was observed to reflect the image. If such a polarizing plate is applied to a liquid crystal display device, the image of the image is deformed. Then, when the size of the liquid crystal display device to be applied is cut from the polarizing plate wound into a roll shape to a product size, the defective product containing the flaw portion is removed. Therefore, reducing such defects is important in the manufacture of polarizing plates.

The present invention has been made in order to solve the above problems, and an object of the invention is to provide a cycloolefin resin film laminated on one surface of a polarizing film composed of a polyvinyl alcohol resin, and an adhesive layer interposed on the other surface. A method of laminating a polarizing plate made of a cellulose resin film is a method of suppressing generation of defects in a polarizing plate.

In the present invention, a cellulose acetate-based resin film is laminated on one surface of a polarizing film composed of a polyvinyl alcohol-based resin, and a polarizing plate is produced by laminating a layer of a cycloolefin-based resin film on the other surface via an adhesive. In the method, the moisture content of the polarizing film before the cellulose acetate-based resin film and the cycloolefin-based resin film is maintained at 8% by weight or more, and a cellulose acetate-based resin film and a cycloolefin system are laminated on the polarizing film. The tension after the resin film is 600 N/m or less.

Here, the moisture content of the polarizing film before laminating the cellulose acetate-based resin film and the cycloolefin-based resin film is preferably maintained at 8 wt% or more and 12 wt% or less.

Further, in the method for producing a polarizing plate of the present invention, it is preferred to dry the cellulose acetate-based resin film and the cycloolefin-based resin film on the polarizing film while maintaining the tension at 600 N/m or less.

According to the present invention, since different types of resin films are laminated on both surfaces of a polarizing film composed of a polyvinyl alcohol-based resin, a protective film composed of the same resin is laminated on both surfaces, and the application can be imparted to the use thereof. A polarizing plate of various characteristics is required, and a polarizing plate which is industrially advantageous to be reduced can be manufactured.

In the method for producing a polarizing plate of the present invention, a cellulose acetate-based resin film is laminated on one surface of a polarizing film composed of a polyvinyl alcohol-based resin via an adhesive layer, and an adhesive layer is laminated on the other surface via an adhesive. A method of producing a polarizing plate from an olefin resin film.

The polyvinyl alcohol-based resin constituting the polarizing film used in the production method of the present invention can be obtained by alkalizing a polyvinyl acetate-based resin. The polyvinyl acetate-based resin may be, for example, a copolymer of vinyl acetate and another monomer copolymerizable therewith, in addition to the single-polymer polyvinyl acetate of vinyl acetate. Other monomers copolymerized with vinyl acetate may, for example, be unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, acrylamides having an ammonium group, and the like. The degree of alkalinity of the polyvinyl alcohol-based resin is usually from 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be further modified, and for example, a polyvinyl polyaldehyde or a polyvinyl acetal modified from an aldehyde may be used. Further, the average degree of polymerization of the polyvinyl alcohol-based resin constituting the polarizing film is usually from 1,000 to 10,000, and preferably from 1,500 to 5,000.

A polyvinyl alcohol-based resin (such as a polyvinyl alcohol-based resin film) is used as a base film of a polarizing film. The method for forming a film of a polyvinyl alcohol-based resin is not particularly limited, and a film can be formed by a known method. The film thickness of the polyvinyl alcohol-based resin film is not particularly limited, and is, for example, 10 to 150 μm.

The polarizing film is usually produced by a step of stretching the polyvinyl alcohol-based resin film by one axis, a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye, and adsorbing the film. The polyvinyl alcohol-based resin film of the dichroic dye is treated with a boric acid aqueous solution and a step of washing with a boric acid aqueous solution.

One-axis extension can be performed before dyeing, either simultaneously with dyeing or after dyeing. When the one-axis extension is performed after the dyeing, the one-axis extension may be performed before the boric acid treatment, or may be performed during the boric acid treatment. Of course, one-axis extension can also be performed in these multiple stages. When performing one-axis extension, one-axis extension may be performed between rolls having different peripheral speeds, or one-axis extension may be performed using a heat roll. Further, it may be a dry stretching such as stretching in the atmosphere, or may be a wet stretching in which the film is expanded in a state of being expanded by a solvent. The stretching ratio is usually 3 to 8 times.

When the polyvinyl alcohol-based resin film is dyed with a dichroic dye, for example, the polyvinyl alcohol-based resin film may be immersed in an aqueous solution containing a dichroic dye. Specifically, an iodine or a dichroic dye can be used as the dichroic dye. Further, the polyvinyl alcohol-based resin film is preferably subjected to a treatment of immersion in water before the dyeing treatment.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing iodine and potassium iodide is usually used for dyeing.

The content of iodine in the 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 to 40 ° C, and further, the time (dyeing time) of immersion in the aqueous solution is usually 20 to 1800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing a water-soluble dichroic dye is usually used for dyeing. The content of the dichroic dye in the aqueous solution is usually 1 × 10 ^-4 to 10 parts by weight per 100 parts by weight of water, and preferably 1 × 10 ^-3 to 1 part by weight. The aqueous solution may also contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the dye aqueous solution used for dyeing is usually 20 to 80 ° C, and further, the time (dyeing time) of immersion in the aqueous solution is usually 10 to 1800 seconds.

The dyed polyvinyl alcohol-based resin film is immersed in an aqueous solution containing boric acid by boric acid treatment after dyeing with a dichroic dye. The amount of boric acid in the aqueous solution containing boric acid is usually 2 to 15 parts by weight per 100 parts by weight of water, and preferably 5 to 12 parts by weight. When iodine is used as the dichroic dye, the aqueous solution containing boric acid preferably contains potassium iodide. The amount of potassium iodide in the aqueous solution containing boric acid is usually 0.1 to 15 parts by weight per 100 parts by weight of water, and preferably 5 to 12 parts by weight. The time of immersion in the aqueous solution containing boric acid is usually 60 to 1200 seconds, preferably 150 to 600 seconds, more preferably 200 to 400 seconds. The temperature of the aqueous solution containing boric acid is usually 50 ° C or more, preferably 50 to 85 ° C, more preferably 60 to 80 ° C.

After the boric acid treatment, the polyvinyl alcohol resin film is usually subjected to a water washing treatment. The water washing treatment is carried out, for example, by immersing a boric acid-treated polyvinyl alcohol-based resin film in water. The water temperature at the time of the water washing treatment is usually 5 to 40 ° C, and the immersion time is usually 1 to 120 seconds. After the water washing, the drying treatment is carried out to obtain a polarizing film. The drying treatment is usually carried out using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually from 30 to 100 ° C, and preferably from 50 to 80 ° C. The drying treatment time is usually 60 to 600 seconds, and preferably 120 to 600 seconds.

In this manner, a polarizing film can be obtained by applying a stretching of a shaft, a dye of a dichroic dye, and a boric acid treatment on a polyvinyl alcohol resin film. The thickness of the polarizing film is usually in the range of 5 to 40 μm, and preferably in the range of 10 to 35 μm. In the method for producing a polarizing plate of the present invention, a cellulose acetate-based resin film is laminated on one surface of a polarizing film composed of a polyvinyl alcohol-based resin via an adhesive, and a cycloolefin-based resin is laminated on the other surface via an adhesive. A polarizing plate is produced by a film.

The cycloolefin-based resin film used in the production method of the present invention is a thermoplastic resin having a unit of a monomer composed of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene-based monomer. A film made of (also called a thermoplastic cycloolefin resin). In the present invention, the cycloolefin resin may be a ring-opening polymer of the above cycloolefin or a hydrogenated product of a ring-opening copolymer of two or more kinds of cyclic olefins, or may be a cyclic olefin, a chain olefin, or a vinyl group. An addition copolymer of an aromatic compound or the like. In addition, it is also effective to introduce a polar base.

When a copolymer of a cyclic olefin and a chain olefin and/or an aromatic compound having a vinyl group is used, the chain olefin may, for example, be ethylene, propylene or the like, and the aromatic compound having a vinyl group may, for example, be styrene or α. -methylstyrene, nucleoalkyl-substituted styrene, and the like. In such a copolymer, the unit of the monomer composed of the cyclic olefin may be 50 mol% or less (preferably 15 to 50 mol%). In particular, when a terpolymer of a cyclic olefin, a chain olefin, and an aromatic compound having a vinyl group is used, a unit of a monomer composed of a cyclic olefin can be made in a smaller amount as described above. In such a terpolymer, the unit of the monomer composed of the chain olefin is usually 5 to 80 mol%, and the unit of the monomer composed of the aromatic compound having a vinyl group is usually 5 to 80 mol%. .

As the cycloolefin-based resin, a commercially available product can be used, for example, Topas (manufactured by Ticona Co., Ltd.), ARTON (manufactured by JSR Co., Ltd.), ZEONOR (manufactured by Japan ZEON Co., Ltd.), and ZEONEX (manufactured by Japan ZEON Co., Ltd.). APEL (Mitsui Chemical Co., Ltd.) and so on. When such a cycloolefin-based resin is formed into a film, a well-known method such as a solvent casting method or a melt extrusion method can be suitably used. In addition, for example, S-SINA (made by Sekisui Chemical Co., Ltd.), SCA40 (made by Sekisui Chemical Co., Ltd.), ZeonorFilm (made by OPTES), etc., may be used. Commercially available film.

As the cycloolefin-based resin film, one-axis extension or biaxial extension can be used. By extending, an arbitrary phase difference value can be given to the cycloolefin type resin film. The stretching is usually carried out continuously while the film roll is being wound up, and in the heating furnace, it is oriented in the direction in which the roll is proceeding, in the direction perpendicular to the direction of progress, or in both directions. The temperature of the furnace is usually in the range of a glass transition temperature close to the cycloolefin resin to a glass transition temperature of +100 °C. The magnification of the extension is usually 1.1 to 6 times, and preferably 1.1 to 3.5 times.

When the cycloolefin-based resin film is wound into a roll shape, the films adhere to each other and tend to cause blocking. Therefore, the film is usually wound around the roll so as to adhere the protective film. In addition, since the cycloolefin-based resin film generally has poor surface activity, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, alkalization treatment, etc., is performed on the surface adjacent to the polarizing film. It is better. Among them, plasma treatment and corona treatment which are relatively easy to implement are preferred.

Further, the cellulose acetate-based resin film used in the production method of the present invention is a film of a part of cellulose or a completely acetated ester, and examples thereof include a film of triacetyl cellulose, a film of diethyl cellulose, and a fiber. A cellulose acetate propionate film or the like. As such a cellulose acetate-based resin film, a commercially available product such as FUJITAC TD80 (manufactured by FUJIFILM Co., Ltd.), FUJITAC TD80UF (manufactured by FUJIFILM Co., Ltd.), KC8UX2M (manufactured by Konica Minolta Opto Co., Ltd.), KC8UY can be used. (Konica Minolta Opto (share) system) and so on. Cellulose acetate is also known as acetaminophen, cellulose acetate.

On the surface of the cellulose acetate-based resin film, surface treatment such as anti-glare treatment, hard coating treatment, antistatic treatment, and anti-reflection treatment may be applied depending on the application. Further, it is also possible to impart an arbitrary retardation value to the cellulose acetate-based resin film by stretching.

When the cellulose acetate-based resin film is wound into a roll shape, the film adheres to each other and tends to be stuck to each other. Therefore, it is usually applied to the end portion of the roll or the tape is inserted into the end portion. Wrap on the roller. Further, in order to improve the adhesion to the polarizing film, the cellulose acetate resin film is usually subjected to alkalizing treatment. The alkalization treatment may be carried out by immersing in an aqueous solution of a base such as sodium hydroxide or potassium hydroxide.

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 as small as possible, but if it is too thin, the strength is lowered and the workability is poor. When it is thick, there is a problem that the transparency is lowered and the weight of the polarizing plate is increased. Accordingly, the appropriate thickness of such films is usually 5 to 200 μm, preferably 10 to 150 μm, more preferably 20 to 100 μm.

In the production method of the present invention, a polarizing film and a cycloolefin resin film are used as an adhesive, and a polarizing film and a cellulose acetate resin film are used as an adhesive, and a cycloolefin resin film and a cycloolefin resin film are also considered. Different types of cellulose acetate resin films are used for the adhesion. However, when the ease of construction or the like is considered together, it is advantageous to use the same adhesive on both sides if the cycloolefin-based resin film and the cellulose acetate-based resin film are to be simultaneously bonded to the polarizing film.

From the viewpoint of thinning the adhesive layer, the adhesive layer is preferably a water-based one (that is, a composition in which an adhesive component is dissolved in water or dispersed in water). For example, a polyvinyl alcohol-based resin or a polyurethane resin is used as a main component, and in order to improve the adhesion, a composition such as an isocyanate compound or an epoxy compound is usually prepared. When such a water-based adhesive is used, the thickness of the adhesive layer is usually 1 μm or less, and the adhesive layer is not actually observed even when the cross section is observed by a general optical microscope.

When a polyvinyl alcohol-based resin is used as a main component of the adhesive, in addition to the partially alkalized polyvinyl alcohol or the fully alkalized polyvinyl alcohol, other modifications such as carboxy-modified polyvinyl alcohol and ethyl acetonitrile may be used. A modified polyvinyl alcohol-based resin such as a polyvinyl alcohol, a methylol-modified polyvinyl alcohol or an amine-modified polyvinyl alcohol. When such a polyvinyl alcohol-based resin is used, an aqueous solution of a polyvinyl alcohol-based resin is used as an adhesive. The concentration of the polyvinyl alcohol-based resin in the adhesive is usually from 1 to 10 parts by weight, and preferably from 1 to 5 parts by weight, based on 100 parts by weight of the water.

In order to improve the adhesion as described above, an epoxy compound or the like can be blended in an adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin. The epoxy compound can be, for example, a water-soluble solution obtained by reacting a polyamidamine polyamine obtained by reacting a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid and epichlorohydrin. Poly-polyamine epoxy resin. Commercial products of such polyamine epoxy resins include, for example, SUMIREZ RESIN 650 (manufactured by Sumitomo Chemtex Co., Ltd.), SUMIREZ RESIN 675 (manufactured by Sumitomo Chemtex Co., Ltd.), and WS-525 (Japan PMC (share) ))). When the epoxy compound is blended, it is usually added in an amount of from 1 to 100 parts by weight, based on 100 parts by weight of the polyvinyl alcohol-based resin, and preferably from 1 to 50 parts by weight.

Here, FIG. 1 is a schematic perspective view showing a state in which a polarizing film, a cellulose acetate-based resin film, and a cycloolefin-based resin film are laminated in a method for producing a polarizing plate of the present invention. In the method for producing a polarizing plate of the present invention, as shown in Fig. 1, after applying an adhesive, a cellulose acetate-based resin is laminated on one surface of a polarizing film 1 composed of a polyvinyl alcohol-based resin via an adhesive. The film 2 is laminated on the other surface of the cycloolefin-based resin film 3 via an adhesive, and is sandwiched by nip rolls 5a and 5b to form a polarizing plate 4. In addition, as shown in FIG. 1, the laminate can be continuously carried out while transporting the polarizing film 1, the cellulose acetate resin film 2, and the cycloolefin resin film 3 in the transport direction A.

The coating method of the subsequent agent may be generally known, and for example, the adhesive may be applied in accordance with a flow casting method, a Mayer method, a bar coating method, a gravure coating method, a die coating method, a dip coating method, a spray method, or the like. The method of coating the film on the back side of one or both of the films or between the two films to be applied. The term "flow casting method" refers to moving the polarizing film or the protective film of the object to be coated in a direction close to the vertical direction, in the horizontal direction, or in an oblique direction therebetween, while allowing the adhesive to flow down and spread on the surface thereof. method.

One of the features of the method for producing a polarizing plate of the present invention is that the moisture content of the polarizing film 1 immediately before the cellulose acetate-based resin film 2 and the cycloolefin-based resin film 3 is maintained at 8% by weight or more. When the moisture content of the polarizing film 1 immediately before the lamination is less than 8% by weight, the resulting polarizing plate 4 tends to have a concave shape. This point is considered to be caused by the following reasons. In other words, when it is assumed that the deformation caused by the depression of the film is directly adhered to and becomes apparent when the film is in contact with the roller, if the moisture content of the polarizing film 1 is low, the polarizing film becomes too hard and becomes difficult to be alleviated. The deformation is so as to become easy to remain after the depression. On the other hand, when the moisture content of the polarizing film 1 immediately before the lamination is excessively high, the drying of the polarizing film 1 is incomplete, and the polarizing film 1 shrinks due to drying after laminating the protective film, so that the obtained polarizing plate 4 is obtained. There will be a tendency to produce unevenness. Therefore, the aforementioned moisture content is preferably 20% by weight or less. Further, the aforementioned moisture content is more preferably in the range of 8 to 12% by weight.

For example, the polarizing film 1 immediately before the cellulose acetate-based resin film 2 and the cycloolefin-based resin film 3 are dried in an oven at 105 ° C for 1 hour, and then calculated from the weights of the following formulas. .

Moisture rate = [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-based resin film 2 and the cycloolefin-based resin film 3 at 8 wt% or more, the polyethylene after washing is appropriately adjusted as described above. The temperature and time when the alcohol resin is dried can be used. 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 the residence time therein. Further, it is also effective to provide a drying furnace in a plurality of stages of two or more, and to adjust the temperature of each drying furnace and the residence time in each drying furnace.

In addition, one of the features of the method for producing a polarizing plate of the present invention is that the tension of the cellulose acetate-based resin film 2 and the cycloolefin-based resin film 3 on the polarizing film 1 is 600 N/m or less. When the aforementioned tension exceeds 600 N/m, it becomes easy to generate pits on the obtained polarizing plate. It is presumed that the greater the tension, the greater the deformation caused by the film contacting the roll. On the other hand, when the tension is too low, since the undulation is likely to occur on the obtained polarizing plate, the above tension is preferably 100 N/m or more. Also, the aforementioned tension is more preferably in the range of 300 to 500 N/m. In addition, the tension after laminating the cellulose acetate-based resin film 2 and the cycloolefin-based resin film 3 on the polarizing film 1 can be carried out by sandwiching the nip rolls 5a and 5b, for example, as shown in Fig. 1, The pulling force is adjusted between another nip roller (not shown) disposed on the downstream side.

In the method for producing a polarizing plate of the present invention, it is preferred to maintain the tension while laminating the cellulose acetate-based resin film 2 on one surface of the polarizing film 1 and laminating the cycloolefin-based resin film 3 on the other surface. Drying treatment is applied to a side of 600 N/m or less. The tension generated on the laminated film is as described above, and can be pulled between the nip rollers 5a and 5b for sandwiching shown in Fig. 1 and another nip roller (not shown) provided on the downstream side. Since the force is adjusted, since the nip roller on the downstream side is often disposed on the downstream side of the drying furnace (for example, near the outlet of the drying furnace), it is preferable to directly perform the drying treatment on the apparatus to maintain the tension after laminating the protective film. Therefore, the aforementioned tension at the time of the drying treatment is also preferably 100 to 600 N/m as well as the tension after laminating the protective film, and more preferably in the range of 300 to 500 N/m.

The drying treatment is carried out, for example, by blowing hot air, but the temperature at this time is usually appropriately selected from the range of 40 to 100 ° C (preferably 60 to 100 ° C). The drying time is usually from 20 to 1200 seconds. After drying, it is preferably cured at room temperature (20 ° C) or at a slightly higher temperature (for example, a temperature of 20 to 50 ° C) for 12 to 600 hours. The temperature at which hardening is carried out is generally set to be lower than the temperature used for drying.

The polarizing plate obtained by the production method of the present invention is usually formed by forming an adhesive layer on one side or both sides thereof. When the adhesive layer is provided on only one surface, either the side of the cycloolefin-based resin film may be laminated or the side of the cellulose acetate-based resin film may be laminated, but the polarizing plate is applied to a liquid crystal display device. In the case where the side of the cycloolefin-based resin film is often laminated toward the liquid crystal cell, an adhesive layer is generally formed on the side of the laminated cycloolefin-based resin film. The thickness of the adhesive layer is usually 5 to 100 μm, and preferably 5 to 40 μm. If the adhesive layer is too thin, the adhesiveness is lowered, and if it is too thick, problems such as overflow of the adhesive tend to occur.

The adhesive for forming the adhesive layer is usually composed of an acrylic resin, a styrene resin, a enamel resin, or the like as a base resin, and an isocyanate compound, an epoxy compound, and a nitrogen-containing compound are added thereto. A cross-linking agent selected from the group consisting of an aziridine compound, and a decane coupling agent.

The surface of the formed adhesive layer is typically protected by a release treated separator film. The separator film is peeled off before the polarizing plate is bonded to the liquid crystal cell or the like.

A polarizing plate with an adhesive layer, usually in the form of a large reel material or a sheet material, is cut by a cutting tool with a sharp blade in order to obtain a polarizing plate having a desired shape and a penetrating axis. Therefore, on the polarizing plate piece obtained by cutting, a state in which the polarizing film is exposed to the outside at the peripheral end portion occurs. When the polarizing plate of this state is subjected to a durability test such as a heat shock test, a polarizing plate which is generally used (for example, a polarizing film formed by laminating a cellulose acetate resin film on both surfaces of a polarizing film) Compared with the board, there is a tendency to cause problems such as peeling and chipping. Therefore, the polarizing plate of the polarizing plate produced by the production method of the present invention preferably has a peripheral end portion continuously cut by a shearing method or the like.

The invention is illustrated in more detail in the following examples, but the invention is not limited by the examples. In the example, the % of the content is shown as a weight basis unless otherwise specified.

(Example 1)

The polyvinyl alcohol film having an average degree of polymerization of about 2400, a degree of alkalinity of 99.9 mol% or more and a thickness of 75 μm was maintained in a tight state, immersed in pure water of 30 ° C to be expanded, and simultaneously extended to the stretching ratio in the longitudinal direction. 1.3 times. The polyvinyl alcohol film was dyed at 30 ° C in an aqueous solution containing iodine and potassium iodide (iodine: potassium iodide: water = 0.05:2:100 (weight ratio)) while maintaining the aforementioned stretching ratio, and then contained at 54 ° C. An aqueous solution of potassium iodide and boric acid (potassium iodide: boric acid: water = 12:5:100 (weight ratio)) was subjected to crosslinking treatment, and simultaneously extended to a total magnification of 5.6 times, and then washed with pure water at 12 °C. The washed polyvinyl alcohol film was sequentially dried in three drying ovens maintained at a temperature of 65 ° C, 75 ° C and 85 ° C, and dried under the condition of a total residence time of 169 seconds to obtain adsorption in polyvinyl alcohol. Samples 1 to 5 of iodine and oriented polarizing film. The obtained samples 1 to 5 were dried in an oven at 105 ° C for 1 hour, and the water content was calculated from the weights before and after the following formula, and found to be 5%.

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

On the other hand, 3 parts by weight of a carboxyl group-modified polyvinyl alcohol (KURARAY POVAL KL318 (manufactured by KURARAY)) and a water-soluble polyamide resin (SUMIREZ RESIN 650 (manufactured by Sumitomo Chemtex Co., Ltd.)) An aqueous solution having a solid concentration of 30%)) 1.5 parts by weight is dissolved in 100 parts by weight of water to prepare a water-based adhesive containing a polyvinyl alcohol-based resin as a main component.

Each of the samples 1 to 5 of the polarizing film was laminated with a film of a norbornene-based resin which was subjected to corona treatment in advance (Zeonor Film (manufactured by OPTES)), as shown in Fig. 1, by the above-mentioned adhesive. , thickness: 80 μm), and a film made of triethyl cerium cellulose (KC8UX2M (manufactured by Konica Minolta Opto Co., Ltd.) having a thickness of 80 μm) which was previously subjected to alkalization treatment was laminated on the other surface by a nip roll fit. At this time, the nip rolls for lamination and the nip rolls on the downstream side (in this example, near the outlet of the drying furnace) are appropriately adjusted, and the tension after lamination of the samples 1 to 5 is changed. Then, it was dried at 80 ° C for 5 minutes while maintaining the tension, and Samples 1 to 5 of the polarizing plate were obtained.

On the other hand, the following samples were prepared in the same manner as in the above samples 1 to 5: the temperature in the first stage was maintained at 50 ° C, the temperature in the second stage was maintained at 65 ° C, and the temperature in the third stage was maintained at 85 ° C. In the three drying furnaces, the polarizing film sample 6 was dried under the condition of a total residence time of 169 seconds to have a water content of 7.9%, and the same conditions as those of the sample 6 were carried out except that the temperature of the drying furnace of the second stage was changed to 60 °C. The polarizing film sample 7 which was dried to have a water content of 9.1%, and the polarizing film sample 8 which was dried under the same conditions as the sample 7 and had a water content of 9.5%, was changed except that the total retention time was changed to 162 seconds. For the samples 6 to 8, the tension after lamination was maintained at 448 N/m, and polarized plate samples 6 to 8 were also prepared.

When the polarizing plate samples 1 to 8 were produced, the inspector visually observed the polarizing plate coming out of the drying furnace, and judged whether or not the concave image was formed by the reflection image of the fluorescent lamp reflected on the surface of the polarizing plate. As described above, when there is a concave shape, the reflection image of the fluorescent lamp is observed to be deformed. Then, by the length of the transport direction of the polarizing plate produced on the line per 100 m, there are several ridges which are observed as described above, and the number of defects is determined. The results are shown in Table 1 in terms of the number of lengths per 100 m (number / 100 m).

It can be seen from Table 1 that although the moisture content of the polarizing film is maintained at 5% and the tension is lowered to reduce the enthalpy, even if the tension is lowered to 448 N/m, the length of the polarizing plate can be observed per 100 m. 10 or so recessed 瑕疵 (sample 5). On the other hand, if the tension is maintained at 448 N/m and the moisture content of the polarizing film is changed, when the moisture content specified in the present invention is 8% or more (9.1% or 9.5%), almost no pits are observed (samples) 7 and 8).

The embodiments and examples disclosed herein are not intended to be exhaustive or to limit the invention. The scope of the present invention is defined by the scope of the claims, and is intended to be

1. . . Polarized film

2. . . Cellulose acetate resin film

3. . . Cycloolefin resin film

4. . . Polarizer

5a, 5b. . . Pinch roller

A. . . Shipping direction

Fig. 1 is a schematic perspective view showing a laminate of a polarizing film, a cellulose acetate resin film, and a cycloolefin resin film in the method for producing a polarizing plate of the present invention.

1. . . Polarized film

2. . . Cellulose acetate resin film

3. . . Cycloolefin resin film

4. . . Polarizer

5a, 5b. . . Pinch roller

A. . . Shipping direction

Claims (2)

A method for producing a polarizing plate, wherein a cellulose acetate-based resin film is laminated on one surface of a polarizing film composed of a polyvinyl alcohol-based resin via a water-based adhesive, and a cycloolefin system is laminated on the other surface via a water-based adhesive. A method of producing a polarizing plate by using a resin film, wherein the moisture content of the polarizing film before laminating the cellulose acetate resin film and the cycloolefin resin film is maintained at 8 wt% or more and 12 wt% or less, and is applied to the polarizing film. The tension after laminating the cellulose acetate-based resin film and the cycloolefin-based resin film is 600 N/m or less. The method for producing a polarizing plate according to the first aspect of the invention, wherein the cellulose acetate-based resin film and the cycloolefin-based resin film are laminated on the polarizing film, and the tension is maintained at 600 N/m or less and dried.