TWI575262B - Method for producing polarizing plate - Google Patents

Description

Polarizing plate manufacturing method

The present invention relates to a method of manufacturing a polarizing plate which can be used as one of optical parts constituting a liquid crystal display device or the like.

A polarizing film is widely used as a dichroic dye in a polyvinyl alcohol-based resin film, and an iodine-based polarizing film containing iodine as a dichroic dye or a dichroic direct dye as a dichroic property is known. The dye of the pigment is a polarizing film or the like. These polarizing films are generally formed by laminating a transparent film such as a triethylenesulfonated cellulose film on one or both sides thereof with an adhesive to form a polarizing plate.

A method of laminating a transparent film on one side or both sides of a polarizing film, after applying an active energy ray-curable resin to a surface of the transparent film in advance, and bonding the polarizing film and the transparent film to each other by a pair of bonding rollers Then, the active energy ray is irradiated and then hardened (see, for example, JP-A-2004-245925 (Patent Document 1), JP-A-2009-134190 (Patent Document 2), and JP-A-2011-95560 Bulletin (Patent Document 3), etc.).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-245925

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2009-134190

[Patent Document 3] Japanese Laid-Open Patent Publication No. 2011-95560

In the polarizing plate in which the polarizing film and the transparent film coated with the active energy ray-curable adhesive on one side are bonded, fine bubbles of about 10 to 50 μm may be mixed between the polarizing film and the transparent film. . It is considered that this bubble is a polarizing film before the roller is bonded to the polarizing film and the transparent film when the bonding roller is rotated while causing the rotation speed of the bonding roller and the conveying speed of the polarizing film and the transparent film. The area between the transparent film and the transparent film creates a flow of air toward the bonding roller, the pressure of which increases due to the trapping of air between the polarizing film and the transparent film.

The present invention has been made to solve the above problems, and an object of the invention is to provide a method of bonding a polarizing film to a polarizing film which is bonded to a transparent film having an active energy ray-curable adhesive on one side thereof. A polarizing plate which is less likely to generate bubbles between the polarizing film and the transparent film can be manufactured.

The method for producing a polarizing plate of the present invention comprises the steps of: performing a dyeing treatment, a boric acid treatment, and a uniaxial stretching treatment on a polyvinyl alcohol-based resin film to form a polarizing film; and coating the active energy on one side of the transparent film. a step of forming a laminate; a step of bonding a surface of the transparent film coated with the surface of the adhesive onto one or both sides of the polarizing film by using a bonding roller; And a step of irradiating the laminate with an active energy ray to form a polarizing plate, wherein the step of preparing the laminate is performed while reducing a wind pressure in a region between the polarizing film and the transparent film before bonding.

The method for manufacturing the polarizing plate of the present invention is preferably by, for example, intervening to fit the roller The obstacle provided between the polarizing film and the transparent film before the bonding is caught, and the wind pressure in the region between the polarizing film and the transparent film before bonding is reduced.

In the method for producing a polarizing plate of the present invention, the air between the polarizing film and the transparent film before bonding can be adhered by the bonding roller, and the polarizing film and the transparent film before bonding can be reduced. Wind pressure in the area between the films.

In the method for producing a polarizing plate of the present invention, the polarizing film and the transparent film before being bonded by the bonding roller may be blown or attracted in a direction orthogonal to the film conveying direction. The wind pressure in the region between the aforementioned polarizing film and the transparent film before bonding is reduced.

According to the production method of the present invention, it is possible to provide a polarizing film which is bonded to a transparent film coated with an active energy ray-curable adhesive on one side, and can be produced in a polarizing film and a transparent film. A method of manufacturing a polarizing plate in which bubbles are less likely to occur.

1‧‧‧ polarizing film

2, 3‧‧‧ transparent film

4‧‧‧Layer

5a, 5b‧‧‧ fitting roller

6‧‧‧ obstacles

7‧‧‧Attraction means

8‧‧‧Air supply or attraction

11, 12‧‧‧ adhesive coating device

13‧‧‧Roller

14, 15‧‧‧1st active energy ray irradiation device

16, 17, ‧ ‧ ‧ after 2nd active energy ray irradiation device

19‧‧‧Clamping roller

20‧‧‧Winding roller

Fig. 1 is a view schematically showing a preferred first example of the present invention.

Fig. 2 is a view schematically showing a second preferred example of the present invention.

Fig. 3 is a view schematically showing a preferred third example of the present invention.

Fig. 4 is a perspective view schematically showing an attraction means 7 which can be suitably used in the present invention.

Fig. 5 is a view schematically showing a fourth example of the present invention.

Fig. 6 is a view schematically showing an example of a whole apparatus for carrying out the method for producing a polarizing plate of the present invention to which the example shown in Fig. 1 is applied.

Fig. 7 is a view schematically showing an example of a whole apparatus for carrying out the method for producing a polarizing plate of the present invention to which the example shown in Fig. 2 is applied.

Fig. 8 is a view schematically showing an example of a whole apparatus for carrying out the method for producing a polarizing plate of the present invention to which the example shown in Fig. 3 is applied.

Fig. 9 is a view schematically showing an example of a whole apparatus for carrying out the method for producing a polarizing plate of the present invention to which the example shown in Fig. 4 is applied.

Fig. 1 is a view schematically showing a preferred first example of the present invention. The method for producing a polarizing plate of the present invention basically comprises the steps of: [1] a step of preparing a polarizing film by subjecting a polyvinyl alcohol-based resin film to dyeing treatment, boric acid treatment, and uniaxial stretching treatment; [2] transparent a step of applying an active energy ray-curable adhesive to one side of the film; [3] bonding the surface of the transparent film coated with the adhesive to one side of the polarizing film by using a bonding roller Or a double-sided step of preparing a laminate; [4] a step of irradiating the laminate with an active energy ray to prepare a polarizing plate. In the method for producing a polarizing plate of the present invention, the step (3) is carried out while reducing the wind pressure in a region between the polarizing film and the transparent film before bonding.

In the first embodiment, the transparent film 2, 3 coated with the active energy ray-curable adhesive on both sides of the polarizing film 1 is sandwiched by the bonding rolls 5a and 5b to form a laminate. 4 examples. In the example shown in Fig. 1, the obstacle 6 is placed so as to be interposed between the polarizing film 1 before the bonding using the bonding rollers 5a and 5b and the transparent films 2 and 3. By providing such an obstacle 6, a region between the polarizing film 1 before the bonding roller and the transparent film 2, and a region between the polarizing film 1 and the transparent film 3 can flow into the bonding roller. The flow of air between 5a and 5b is chaotic, which can reduce the wind pressure in the above area. Thereby, when bonding, it can be reduced in the polarizing film The amount of air trapped between the transparent film and the resulting polarizing plate suppresses the occurrence of bubbles.

In the example shown in Fig. 1, the obstacle 6 is not particularly limited as long as it can confuse the flow of air as described above, but for example, a plate, a rod, or a rope is involved. It suffices that the region between the polarizing film and the transparent film before the rollers 5a and 5b are bonded to each other. The size of such a plate or rod is not particularly limited, but preferably covers the entire width direction of the film (direction perpendicular to the conveying direction) and is filled with air as described above, so it is preferable to use a film larger than the film. The width direction of the person. Specifically, a plate, a rod, or a rope having a thickness or a diameter in the range of 0.1 to 30 mm and a length in the range of 600 to 2,500 mm can be exemplified. Further, the plate, the rod, or the rope may be either hollow or solid. Further, the material of the plate or the rod is not particularly limited, but it is preferably a metal such as SUS 304, SUS 316, aluminum, carbon fiber, or nylon, Teflon (registered trademark), and further such as PEEK, PES. A plate, a rod, or a rope formed of a rigid resin such as a liquid crystal polymer (LCP).

Further, Fig. 2 is a view schematically showing a second preferred example of the present invention. In the example shown in Fig. 2, the air between the polarizing film 1 and the transparent films 2 and 3 before the bonding of the bonding rollers 5a and 5b is attracted by the suction means 7 to reduce the fit. The wind pressure of the area between the previous polarizing film 1 and the transparent films 2, 3. In addition, the example shown in FIG. 2 is the same as the example shown in FIG. 1 except that the obstacle 7 is replaced by the suction means 7, and the same components are denoted by the same reference numerals, and the description thereof is omitted.

Further, Fig. 3 is a view schematically showing a third example of the present invention. In the example shown in Fig. 3, only the film before the bonding roller 5a, 5b is caught by the bonding roller 5a, 5b is biased. The laminate 1' and the transparent film 2 of the light film 1 or the polarizing film and the other film are the same as the example shown in Fig. 2 except that the suction device 7 is a suction device (pressure reducing device) as shown in the figure. The same components are denoted by the same reference numerals, and description thereof will be omitted.

The examples shown in Figs. 2 and 3 are in the region between the polarizing film 1 and the transparent film 2 before the bonding roller, or in the region between the polarizing film 1 and the transparent film 3, and will flow in the sticker. The flow of air between the rollers 5a and 5b is actively attracted by the suction means 7, and the wind pressure in the above region can be reduced. The suction means 7 used is, for example, a suction device as shown in Fig. 3. In this case, the amount of pressure reduction (pressure difference) in the apparatus is 0.4 kPa or more, preferably 1.0 kPa or more, more preferably 1.5 to 3.0 kPa. . Further, the amount of pressure reduction means a value obtained by measuring the pressure in the apparatus by a pressure difference meter using a pressure reducing pump. Even in this case, the amount of air trapped between the polarizing film and the transparent film can be reduced at the time of bonding, and generation of bubbles can be suppressed in the obtained polarizing plate. In the examples shown in Figs. 2 and 3, the suction means 7 to be used is not particularly limited, and any conventionally known suction means can be used, and the apparatus having the configuration of Fig. 4 can be suitably used.

Further, Fig. 5 is a view schematically showing a fourth example of the present invention. In the example shown in FIG. 5, the wind is applied between the polarizing film 1 and the transparent films 2 and 3 before the bonding roller 5 is attached, and the wind is fed in the direction orthogonal to the film conveying direction, or Attraction reduces the wind pressure in the region between the polarizing film 1 and the transparent films 2, 3 before bonding. In addition, the example shown in FIG. 5 is the same as the example shown in FIG. 1 except that the air blower or the suction means 8 is used instead of the obstacle 6, and the same components are denoted by the same reference numerals, and description thereof will be omitted.

In the example shown in Fig. 5, in the region between the polarizing film 1 and the transparent film 2 before the bonding roller, and in the region between the polarizing film 1 and the transparent film 3 The flow of the air flowing into the film transport direction between the bonding rollers 5a and 5b causes the wind in the direction orthogonal thereto to feed or suck the flow of the chaotic air from the side surface, thereby reducing the wind pressure in the above region. In this way, the amount of air trapped between the polarizing film and the transparent film can be reduced at the time of bonding, and generation of bubbles can be suppressed in the obtained polarizing plate. In the example shown in Fig. 5, the air blowing or suction means 8 to be used is not particularly limited, and any conventionally known air blowing or suction means may be used. Further, the air supply or the suction direction is not particularly limited, and may be from one side or both sides.

In addition, in the first, second, and fifth figures, the transparent film 2 and 3 are bonded to the double-sided side of the polarizing film 1, but the polarizing film 1 may be used as in the third drawing. The transparent film 2 is bonded to one another. In this case, a laminate of a transparent film or a protective film or a backing film may be laminated in advance on the side which is not bonded to the transparent film of the polarizing film.

Here, Fig. 6 is a view schematically showing an example of a whole apparatus for carrying out the method for producing a polarizing plate of the present invention to which the example shown in Fig. 1 is applied, and Fig. 7 is a schematic view showing the application of the first embodiment. 2 is a view showing an example of a whole apparatus for manufacturing a polarizing plate of the present invention, and FIG. 8 is a view schematically showing a method of manufacturing a polarizing plate of the present invention for applying the example shown in FIG. FIG. 9 is a view schematically showing an example of the entire apparatus for manufacturing the polarizing plate of the present invention to which the example shown in FIG. 5 is applied. FIG. Hereinafter, the entire method of manufacturing the polarizing plate of the present invention will be described in detail with reference to FIGS. 6 , 7 , 8 , and 9 .

[1] Steps of making a polarizing film

In the method for producing a polarizing plate of the present invention, first, the polyvinyl alcohol resin is thin. The film was subjected to dyeing treatment, boric acid treatment, and uniaxial stretching treatment to prepare a polarizing film. The polarizing film used in the present invention is specifically a one in which a uniaxially stretched polyvinyl alcohol-based resin film is adsorbed to a dichroic dye. The polyvinyl alcohol-based resin film can be obtained by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate-based resin may, for example, be a polyvinyl acetate of a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable therewith (for example, ethylene-acetic acid) Vinyl ester copolymer) and the like. Other single systems which can be copolymerized with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl esters, unsaturated sulfonic acids, acrylamides having an ammonium group, and the like. The degree of saponification of the polyvinyl alcohol-based resin is 85 mol% or more, preferably 90 mol% or more, and most preferably 98 to 100 mol%. The average degree of polymerization of the polyvinyl alcohol-based resin is generally from 1,000 to 10,000, preferably from 1,500 to 5,000. These polyvinyl alcohol-based resins may be modified, and for example, aldehyde-modified polyethylene formaldehyde, polyvinyl acetaldehyde, polyvinyl butyral or the like may be used.

A film made of such a polyvinyl alcohol-based resin can be used as a raw material film as 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 conventionally known appropriate method. The film thickness of the raw material film made of a polyvinyl alcohol-based resin is not particularly limited, but is, for example, about 10 to 150 μm. In general, it may be supplied in the form of a roll having a thickness in the range of 20 to 100 μm, preferably in the range of 30 to 80 μm, and an industrially practical width in the range of 1,500 to 6,000 mm.

Commercially available polyvinyl alcohol-based film (Vinylon VF-PS #7500, Kuraray/OPL film, M-7500, manufactured by Nippon Synthetic Co., Ltd.) has a thickness of 75 μm (Vinylon VF-PS # 6000, manufactured by Kuraray, Vinylon VF) -PE # 6000, manufactured by Kuraray) The thickness of the raw material is 60 μm.

The polarizing film is generally produced by the following steps: making a polyvinyl alcohol resin film a step of dyeing a dichroic dye by dyeing a dichroic dye (dyeing step), a step of treating a polyvinyl alcohol-based resin film having a dichroic dye adsorbed with an aqueous solution of boric acid (boric acid treatment step), and an aqueous solution of boric acid The step of washing with water after the treatment (water washing treatment step).

Further, in the production of the polarizing film, generally, the polyvinyl alcohol resin film is uniaxially stretched, but the uniaxial stretching may be performed before the dyeing step, or in the dyeing step, or in the dyeing step. After that. When the uniaxial stretching is performed after the dyeing treatment step, the uniaxial stretching may be performed before the boric acid treatment step or in the boric acid treatment step. Of course, uniaxial stretching can also be performed at these multiple stages.

The uniaxial extension system can be extended to a single axis between rolls having different circumferential speeds, or can be extended to a single axis using a hot roll. Further, it may be a dry stretching which is extended in the atmosphere, or may be a wet stretching which is extended in a state in which the solvent is swollen. The stretching ratio is generally about 3 to 8 times.

The dyeing of the polyvinyl alcohol-based resin film in the dyeing treatment step by the dichroic dye is carried out, for example, by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. As the dichroic dye system, for example, iodine, a dichroic dye or the like can be used. The dichroic dye includes a dichroic direct dye composed of a disazo compound such as C.I. DIRECT RED 39, and a dichroic direct dye composed of a compound such as azo or hydrazine azo. Further, the polyvinyl alcohol-based resin film is preferably subjected to immersion treatment 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 and dyed is generally used. The content of iodine in the aqueous solution is generally 0.01 to 1 part by weight per 100 parts by weight of water, iodide The potassium content is generally from 0.5 to 20 parts by weight per 100 parts by weight of the water. When iodine is used as the dichroic dye, the temperature of the aqueous solution used for dyeing is generally 20 to 40 ° C, and the immersion time (dyeing time) of the aqueous solution is generally 20 to 1800 seconds.

Further, 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 an aqueous dichroic dye and dyed is generally used. The content of the dichroic dye in the aqueous solution is generally from 1 × 10 ^-4 to 10 parts by weight, preferably from 1 × 10 ^-3 to 1 part by weight, particularly preferably 1 × 10 ^- per 100 parts by weight of water ^{. 3} to 1 × 10 ^-2 parts by weight. The aqueous solution may also contain an inorganic salt such as sodium sulfate as a dyeing auxiliary. When a dichroic dye is used as the dichroic dye, the temperature of the dye aqueous solution used for dyeing is generally 20 to 80 ° C, and the immersion time (dyeing time) of the aqueous solution is usually 10 to 1800 seconds.

The boric acid treatment step is carried out by immersing the polyvinyl alcohol-based resin film dyed with the dichroic dye in an aqueous solution containing boric acid. The amount of boric acid in the aqueous solution containing boric acid is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye in the above dyeing treatment step, the aqueous boric acid solution used in the boric acid treatment step preferably contains potassium iodide. At this time, the amount of potassium iodide in the aqueous solution containing boric acid is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of the water. The immersion time in the aqueous solution containing boric acid is generally from 60 to 1200 seconds, preferably from 150 to 600 seconds, more preferably from 200 to 400 seconds. The temperature of the aqueous solution containing boric acid is usually 40 ° C or higher, preferably 50 to 85 ° C, more preferably 55 to 75 ° C.

Then, the water washing treatment step is performed by subjecting the above-described boric acid-treated polyvinyl alcohol-based resin film to water, for example, by immersing in water. The temperature of the water in the water washing treatment is generally 4 to 40 ° C, and the immersion time is usually 1 to 120 seconds. Washing treatment Thereafter, drying treatment is generally carried out to obtain a polarizing film. The drying treatment is preferably carried out using, for example, a hot air dryer, a far infrared heater or the like. The temperature of the drying treatment is usually from 30 to 100 ° C, preferably from 50 to 80 ° C. The drying treatment time is generally from 60 to 600 seconds, preferably from 120 to 600 seconds.

In this manner, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, boric acid treatment, and water washing treatment to obtain a polarizing film. The thickness of the polarizing film is generally in the range of 5 to 50 μm.

[2] Step of coating an active energy ray-curable adhesive on a transparent film (transparent film)

The material constituting the transparent film used in the present invention may, for example, be a cycloolefin resin or a cellulose acetate resin such as polyethylene terephthalate or polyethylene naphthalate or polybutylene terephthalate. A polyester resin such as an ester resin, a polycarbonate resin, an acrylic resin, or a polypropylene is widely used as a film material in the field.

The cycloolefin resin is a thermoplastic resin (also referred to as a thermoplastic cycloolefin resin) having a unit of a monomer composed of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene monomer. . The cycloolefin resin may be a ring-opening polymer of the above cycloolefin or a hydrogenated product of a ring-opening polymer using two or more kinds of cycloolefins, or a cyclic olefin, a chain olefin, an aromatic compound having a vinyl group, or the like. Addition polymer. Also, it is effective to introduce a polar base.

When a copolymer of a cycloolefin and a chain olefin and/or an aromatic compound having a vinyl group is used, the chain olefin may, for example, be ethylene or propylene, and the aromatic compound having a vinyl group may, for example, be styrene. 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, the use of cyclic olefins In the case of a terpolymer of a chain olefin and an aromatic compound having a vinyl group, the unit of the monomer composed of the cyclic olefin may be a relatively small amount as described above. In such a terpolymer, the unit of the monomer composed of the chain olefin is generally 5 to 80 mol%, and the unit of the monomer composed of the aromatic compound having a vinyl group is generally 5 to 80 mol. ear%.

For the cycloolefin-based resin, an appropriate commercially available product can be suitably 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.), OXIS (manufactured by Okura Industrial Co., Ltd.), etc. When a film is formed by forming a film of such a cycloolefin-based resin, a known method such as a solvent casting method or a melt-extrusion method can be suitably used. Further, for example, a film made of a cycloolefin-based resin which has been previously formed into a film such as Escena (manufactured by Sekisui Chemical Co., Ltd.), SCA 40 (manufactured by Sekisui Chemical Co., Ltd.), or Zeonor Film (manufactured by Optes) may be used. Commercial products.

The cycloolefin resin film may be one which is uniaxially stretched or biaxially stretched. Any phase difference value can be imparted to the cycloolefin resin film by stretching. The extension is generally performed while the film roll is being wound out, and the heating furnace extends in the traveling direction of the roll (the longitudinal direction of the film), the direction perpendicular to the traveling direction (the width direction of the film), or both. The temperature of the heating furnace is generally in the range from the vicinity of the glass transition temperature of the cycloolefin resin to the glass transition temperature + 100 °C. The extension ratio is generally 1.1 to 6 times, preferably 1.1 to 3.5 times.

When the cycloolefin-based resin film is wound in a roll state, the films tend to block each other and tend to block. Therefore, the roll is wound after the protective film is generally bonded. Further, the cycloolefin-based resin film is generally poor in surface activity, and the surface of the polarizing film is preferably subjected to plasma treatment, corona treatment, ultraviolet irradiation treatment, Surface treatment such as flame treatment and saponification. Among them, it is suitable for plasma treatment which can be relatively easily carried out, and is particularly suitable for atmospheric piezoelectric slurry treatment and corona treatment.

The cellulose acetate-based resin is a partial or complete esterified product, and examples thereof include a cellulose acetate, a propionate, a butyrate, and a mixed ester of these. More specifically, for example, a triethylenesulfonated cellulose film, a diethylidene cellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film, or the like can be given. As such a cellulose ester-based resin film, a commercially available product such as Fujitac TD 80 (manufactured by Fuji Film Co., Ltd.), Fujitac TD 80UF (manufactured by Fuji Film Co., Ltd.), and Fujitac TD 80UZ (Fuji Film) can be suitably used. )), KC 8UX 2M (Konica Minolta Opto Co., Ltd.), KC8UY (Konica Minolta Opto Co., Ltd.), Fujitac TD 60UL (Fuji Film Co., Ltd.), KC4UYW (Konica Minolta Opto Co., Ltd.) , KC6UAW (Konica Minolta Opto (share) system) and so on.

Moreover, as for the transparent film, a cellulose acetate-based resin film which imparts phase difference characteristics can be suitably used. Commercially available products of the cellulose acetate-based resin film having such a phase difference characteristic are, for example, WV BZ 438 (manufactured by Fuji Film Co., Ltd.), KC4FR-1 (manufactured by Konica Minolta Opto Co., Ltd.), and KC4CR-1 ( Konica Minolta Opto Co., Ltd., KC4AR-1 (Konica Minolta Opto Co., Ltd.), and the like. Cellulose acetate is also known as acetaminocellulose or is also known as cellulose acetate.

These cellulose acetate-based films are easy to absorb water, and the moisture content of the polarizing plate affects the relaxation of the ends of the polarizing plates. The water content at the time of manufacture of the polarizing plate is closer to the storage environment of the polarizing plate, for example, the manufacturing line of the clean room or the equilibrium moisture content in the roll winding storage warehouse is better, depending on the composition of the laminated film, for example, It is about 2.0 to 3.5%, more preferably 2.5 to 3.0%. The numerical value of the moisture content of the polarizing plate was measured by the dry weight method and was changed by weight after 105 ° C / 120 minutes.

In the present invention, the transparent film can have a function as a retardation film, a function as a brightness enhancement film, a function as a reflection film, a function as a semi-transmissive reflection film, a function as a diffusion film, a function as an optical compensation film, and the like. Optical function. In this case, for example, an optical functional film such as a surface laminated retardation film, a brightness enhancement film, a reflective film, a semi-transmissive reflection film, a diffusion film, or an optical compensation film may be used in addition to the function of the transparent film. This function is imparted to the transparent film itself. Further, a diffusion film having a function as a brightness enhancement film or the like may have a plurality of functions in the transparent film.

For example, the above-mentioned transparent film can be subjected to the stretching treatment described in Japanese Patent No. 2841377, Japanese Patent No. 3094113, or the like, or the treatment described in Japanese Patent No. 3168850 can be applied as a retardation film. Features. The phase difference characteristic of the retardation film can be appropriately selected, for example, in the range of the front phase difference value of 5 to 100 nm, the thickness direction retardation value of 40 to 300 nm, and the like. In addition, the above-mentioned transparent film is formed into fine pores by the method described in JP-A-2002-169025 or JP-A-2003-29030, or two or more layers of cholesteric liquid crystals having different center wavelengths of reflection and reflection are overlapped. The layer, 俾 can be imparted as a function of the brightness enhancement film.

When the transparent film described above is formed into a metal thin film by vapor deposition or sputtering, it can be provided as a reflective film or a semi-transmissive reflective film. By applying the resin solution containing fine particles to the above transparent film, it is possible to impart a function as a diffusion film. Moreover, the transparent film is coated with a liquid crystal compound such as a discotic liquid crystal compound, and the film can be provided as an optical compensation film. Further, a compound having a phase difference may be contained in the transparent film. Further, various optical functional films may be directly bonded to the polarizing film by using an appropriate adhesive. Optical function For example, a brightness-enhancing film such as DBEF (made by 3M Company, available from Sumitomo 3M (shares) in Japan), or a WV film (made by Fujifilm Co., Ltd.) can be used as a commercially available product. JSR (share) system, Zeonor Film (made by Optes), Escena (made by Sekisui Chemical Industry Co., Ltd.), VA-TAC (Konica Minolta Opto), Sumika light (Sumitomo Chemical Co., Ltd.) ) A retardation film or the like.

The thickness of the transparent film used in the present invention is preferably thin, but if it is too thin, the strength is lowered and the workability is deteriorated. On the other hand, if it is too thick, the transparency is lowered, and the hardening time required after lamination becomes long. Therefore, a suitable thickness of the transparent film is, for example, 5 to 200 μm, preferably 10 to 150 μm, more preferably 10 to 100 μm.

In order to improve the adhesion between the adhesive and the polarizing film and/or the transparent film, the polarizing film and/or the transparent film may be subjected to corona treatment, flame treatment, plasma treatment, ultraviolet treatment, primer coating treatment, Surface treatment such as saponification treatment.

Further, in the transparent film system, surface treatment such as anti-glare treatment, anti-reflection treatment, hard coating treatment, antistatic treatment, and antifouling treatment may be carried out alone or in combination of two or more. Further, the transparent film and/or the transparent film surface protective layer may contain a UV absorber such as a benzophenone compound or a benzotriazole compound, or a plasticizer such as a phenyl phosphate compound or a phthalate compound.

(active energy ray hardening type adhesive)

The active energy ray-curable adhesive is composed of, for example, an epoxy resin composition containing an epoxy resin which is cured by irradiation with an active energy ray, from the viewpoints of weather resistance, refractive index, and cationic polymerizability. The adhesive. However, the present invention is not limited thereto, and various active energy ray-curable adhesives (organic solvent-based adhesives, hot-melt adhesives, solventless adhesives, etc.), such as propylene, which have been conventionally used for the production of polarizing plates, can be used. Indoleamine, acrylate, urethane acrylate, epoxy acrylate An adhesive or the like composed of an acrylic resin composition such as an ester.

The epoxy resin means a compound having two or more epoxy groups in the molecule. From the viewpoints of weather resistance, refractive index, cationic polymerizability, and the like, the epoxy resin contained in the curable epoxy resin composition of the adhesive is preferably an epoxy resin which does not contain an aromatic ring in the molecule (see, for example, a patent) Document 1). Such an epoxy resin may, for example, be a hydrogenated epoxy resin, an alicyclic epoxy resin, an aliphatic epoxy resin or the like.

The hydrogenated epoxy resin can be subjected to glycidyl etherification by a nuclear hydrogenation polyol obtained by selectively hydrogenating a polyhydroxy compound of a raw material of an aromatic epoxy resin in the presence of a catalyst under pressure. The method to get. Examples of the aromatic epoxy resin include bisphenol type epoxy resins such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and bisphenol S diglycidyl ether; and phenol novolac varnishes; Epoxy resin, cresol novolac epoxy resin, and phenolic novolac epoxy resin such as novolac type epoxy resin; glycidyl ether of tetrahydroxyphenylmethane and shrinkage of tetrahydroxybenzophenone A polyfunctional epoxy resin such as glyceryl ether or epoxidized polyvinyl phenol. Among the hydrogenated epoxy resins, a glycidyl ether of hydrogenated bisphenol A is preferred.

The alicyclic epoxy resin means an epoxy resin having one or more epoxy groups bonded to an alicyclic ring in the molecule. The "epoxy group bonded to the alicyclic ring" means the oxygen atom -O- of the bridge in the structure shown by the following formula. In the following formula, m is an integer of 2 to 5.

A compound in which one or a plurality of hydrogen atoms are removed in the formula (CH ₂ ) _m in the above formula and is bonded to another chemical structure may be an alicyclic epoxy resin. One or a plurality of hydrogen atoms of (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among the alicyclic epoxy resins, an epoxy resin having an oxabicyclohexane ring (m=3 in the above formula) or an oxabicycloheptane ring (in the above formula, m=4) It is better to use it in terms of excellent adhesion. Hereinafter, the alicyclic epoxy resin which is preferably used is specifically exemplified, but the compound is not limited thereto.

(a) an epoxycyclohexylmethylepoxycyclohexanecarboxylate represented by the following formula (I); (wherein R ¹ and R ² independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(b) an epoxycyclohexane carboxylate of an alkanediol represented by the following formula (II): (wherein R ³ and R ⁴ independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and n is an integer of 2 to 20).

(c) an epoxycyclohexylmethyl ester of a dicarboxylic acid represented by the following formula (III); (wherein R ⁵ and R ⁶ independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and p is an integer of 2 to 20).

(d) Epoxycyclohexyl methyl ethers of polyethylene glycol represented by the following formula (IV): (wherein R ⁷ and R ⁸ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and q is an integer of 2 to 10).

(e) an epoxycyclohexyl methyl ether of an alkanediol represented by the following formula (V): (wherein R ⁹ and R ¹⁰ independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and r is an integer of 2 to 20).

(f) a diepoxy trispiro compound represented by the following formula (VI); (wherein R ¹¹ and R ¹² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(g) a diepoxy monospiro compound represented by the following formula (VII); (wherein R ¹³ and R ¹⁴ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(h) Vinylcyclohexene diepoxides represented by the following formula (VIII): (wherein R ¹⁵ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(i) Epoxycyclopentyl ethers represented by the following formula (IX): (wherein R ¹⁶ and R ¹⁷ independently of each other represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

(j) Dicyclooxy tricyclodecanes represented by the following formula (X): (wherein R ¹⁸ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms).

Among the alicyclic epoxy resins exemplified above, those of the alicyclic epoxy resin described later, or the like, are preferably used because they are relatively easy to obtain.

(A) an ester of 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid with (7-oxa-bicyclo[4.1.0]heptan-3-yl)methanol [in formula (I) , compound with R ¹ =R ² =H], (B) 4-methyl-7-oxabicyclo[4.1.0]heptane-3-carboxylic acid and (4-methyl-7-oxa-bicyclic ring) [4.1.0]Hept-3-yl)methanol ester [in formula (I), R ¹ =4-CH ₃ , R ² =4-CH ₃ compound], (C) 7-oxabicyclo [4.1.0] An esterified product of heptane-3-carboxylic acid and 1,2-ethanediol [in the formula (II), a compound of R ³ = R ⁴ = H, n = 2], (D) ( An ester of 7-oxabicyclo[4.1.0]heptan-3-yl)methanol with adipic acid [in the formula (III), a compound of R ⁵ =R ⁶ =H, p=4], (E) ( Esterified product of 4-methyl-7-oxabicyclo[4.1.0]heptan-3-yl)methanol with adipic acid [In formula (III), R ⁵ =4-CH ₃ , R ⁶ =4- a compound of CH ₃ , p=4], (F) (7-oxabicyclo[4.1.0]heptan-3-yl)methanol and 1,2-ethanediol ether [in formula (V), R ⁹ = R ¹⁰ = H, n = 2 of the compound].

Further, the aliphatic epoxy resin may, for example, be a polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof. More specifically, for example, diglycidyl ether of 1,4-butanediol; diglycidyl ether of 1,6-hexanediol; triglycidyl ether of glycerol; three of trimethylolpropane Glycidyl ether; diglycidyl ether of polyethylene glycol; diglycidyl ether of propylene glycol; aliphatic polyols such as ethylene glycol, propylene glycol, and glycerin are added in one or more alkylene oxides (rings) Polyglycidyl ether of a polyether polyol obtained by oxyethane or propylene oxide.

The epoxy resin which is a binder which consists of an epoxy resin composition can be used individually by 1 type, and can also use 2 or more types together. The epoxy resin used in the composition has an epoxy equivalent of usually from 30 to 3,000 g/equivalent, preferably from 50 to 1,500 g/equivalent. When the epoxy equivalent is less than 30 g/eq, the flexibility of the composite polarizing plate after curing may be lowered, or the strength may be lowered. On the other hand, when it exceeds 3000 g/eq, the compatibility with other components contained in the adhesive may be lowered.

In this adhesive, from the viewpoint of reactivity, cationic polymerization is preferably used in the curing reaction of the epoxy resin. Therefore, it is preferred to incorporate a cationic polymerization initiator in the curable epoxy resin composition of the active energy ray-curable adhesive. Cationic polymerization initiators are active energy lines such as visible light, ultraviolet light, X-rays, and electron beams. The cationic species or Lewis acid is generated by irradiation to initiate the polymerization of the epoxy group. Hereinafter, a cationic polymerization initiator which generates a cationic species or a Lewis acid by irradiation with an active energy ray and starts the polymerization of an epoxy group is referred to as a "photocationic polymerization initiator".

The use of a photocationic polymerization initiator to cure the adhesive by irradiation of an active energy ray makes it possible to harden at room temperature, and it is necessary to reduce the deformation caused by heat resistance or expansion of the polarizing film, and to form a film. It is advantageous in terms of good follow-up. Further, since the photocationic polymerization initiator acts by photocatalytic activity, it is excellent in storage stability and workability even when it is mixed in an epoxy resin.

The photocationic polymerization initiator may, for example, be an aromatic diazolium salt; an onium salt such as an aromatic iodonium salt or an aromatic onium salt; an iron-accumulated diene (iron-allene) complex.

The aromatic diazo hydrazine salt may, for example, be benzodiazepine hexafluoroantimonate, benzodiazepine hexafluorophosphate or benzodiazepine hexafluoroborate. Further, examples of the aromatic iodonium salt include diphenyliodonium (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, and di(4). - mercaptophenyl) iodonium hexafluorophosphate or the like.

Examples of the aromatic onium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium (pentafluorophenyl) borate, and 4,4'-bis(diphenyl). Diphenyl sulfide bis(hexafluorophosphate), 4,4'-bis[bis(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide bis(hexafluoroantimonate) , 4,4'-bis[bis(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide bis(hexafluorophosphate), 7-[bis(p-tolylmethyl) fluorenyl] 2-isopropylthione onion hexafluoroantimonate, 7-[bis(p-tolylmethylhydrazino)indolyl]-2-isopropylthioxanthone (pentafluorophenyl)borate, 4-phenylcarbonyl-4'-diphenylfluorenyl- Diphenyl sulfide hexafluorophosphate, 4-(p-tert-butylphenylcarbonyl)-4'-diphenylfluorenyl-diphenyl sulfide hexafluoroantimonate, 4-(paired third Phenylphenylcarbonyl)-4'-bis(p-tolylmethyl) fluorenyl-diphenyl sulfide quinone (pentafluorophenyl) borate.

Further, examples of the iron-accumulating diene complex compound include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, and Toluene-cyclopentadienyl iron (II)- cis (trifluoromethylsulfonyl) methide or the like.

Commercially available products of such photocationic polymerization initiators are readily available. For example, "Kayarad PCI-220" and "Kayarad PCI-620" (above, Nippon Kayaku Co., Ltd.), "UVI-6990" (manufactured by Union Carbide Co., Ltd.), "Adeka optomer" SP-150" and "Adeka optomer SP-170" (above, ADEKA (share) system), "CI-5102", "CIT-1370", "CIT-1682", "CIP-1866S", "CIP-2048S" And "CIP-2064S" (above, Japan's Soda (share) system), "DPI-101", "DPI-102", "DPI-103", "DPI-105", "MPI-103", "MPI -105", "BBI-101", "BBI-102", "BBI-103", "BBI-105", "TPS-101", "TPS-102", "TPS-103", "TPS-105" "MDS-103", "MDS-105", "DTS-102" and "DTS-103" (above, Midori Chemical Co., Ltd.), "PI-2074" (manufactured by Rhodia Co., Ltd.).

The photocationic polymerization initiator may be used singly or in combination of two or more. Among them, the aromatic sulfonium salt has ultraviolet absorbing properties even in a wavelength region of 300 nm or more, and therefore it is preferably used because it can provide a cured product having excellent curability and good mechanical strength or adhesion strength.

The blending amount of the photocationic polymerization initiator is generally 0.5 to 20 parts by weight, preferably 1 part by weight or more, and preferably 15 parts by weight or less based on 100 parts by weight of the epoxy resin. The amount of the photocationic polymerization initiator blended is relative to the epoxy resin 100 When the amount is less than 0.5 part by weight, the hardening is insufficient, and the mechanical strength or the subsequent strength tends to decrease. In addition, when the amount of the photocationic polymerization initiator is more than 20 parts by weight based on 100 parts by weight of the epoxy resin, the ionic substance in the cured product increases, and the hygroscopic property of the cured product becomes high, and the durability may be high. reduce.

When a photocationic polymerization initiator is used, the curable epoxy resin composition may further contain a photosensitizer as needed. With the use of a photosensitizer, the reactivity of the cationic polymerization is improved, and the mechanical strength or the strength of the cured product can be improved. The photosensitizer may, for example, be a carbonyl compound, an organic sulfur compound, a persulfide compound, a redox compound, an azo or diazo compound, a halogen compound or a photoreductive dye.

Specific examples of the photosensitizer include benzoin methyl ether, benzoin isopropyl ether, and benzoin such as α,α-dimethoxy-α-phenylethyl benzene. a derivative; benzophenone, 2,4-dichlorobenzophenone, methyl ortho-benzoylbenzoate, 4,4'-bis(dimethylamino)benzophenone, and 4, a benzophenone derivative such as 4'-bis(diethylamino)benzophenone; a thione onone derivative such as 2-chlorothianicone or 2-isopropylthiolenac; 2 - chlorophyll 醌, and 2-methyl onion 醌 醌 醌 derivatives; N-methyl acridone, and N-butyl acridone and other acridone derivatives; other, α, α-diethoxy Ethyl benzene, benzil, anthrone, xanthonone, uranyl compound, halogen compound, and the like. The photosensitizer may be used alone or in combination of two or more. The photosensitizer is preferably contained in an amount of from 0.1 to 20 parts by weight per 100 parts by weight of the curable epoxy resin composition.

The epoxy resin contained in the subsequent agent is hardened by photocationic polymerization, but may be hardened by both photocationic polymerization and thermal cationic polymerization. In the latter case, it is preferred to use a photocationic polymerization initiator together with a thermal cationic polymerization initiator.

The thermal cationic polymerization initiator may, for example, be a benzyl sulfonium salt, a thiophene sulfonium salt, or a tetra A thiolanium salt, a benzylammonium salt, a pyridinium salt, a hydrazine salt, a carboxylic acid ester, a sulfonate, an amine imine or the like. Such a thermal cationic polymerization initiator can be easily obtained as a commercial product, and any of them may be, for example, "Adeka opton CP77" and "Adeka opton CP66" (above, ADEKA Co., Ltd.) "CI-2639" and "CI-2624" (above, manufactured by Japan Soda Co., Ltd.), "Sun-aid SI-60L", "Sun-aid SI-80L" and "Sun-aid SI-100L" ( Above, Sanshin Chemical Industry Co., Ltd.) and so on.

The active energy ray-curable adhesive may further contain a compound which promotes cationic polymerization such as oxetane or polyol.

The propylene oxide is a compound having a 4-membered cyclic ether in the molecule, and examples thereof include 3-ethyl-3-hydroxymethyl propylene oxide and 1,4-bis[(3-ethyl-3-epoxypropane). Methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl) propylene oxide, bis[(3-ethyl-3-epoxypropenyl)methyl]ether, 3- Ethyl-3-(2-ethylhexyloxymethyl) propylene oxide, phenol novolac propylene oxide, and the like. These propylene oxides are easily available in the case of commercially available products, and any of them may be referred to as "Aron oxetane OXT-101", "Aron oxetane OXT-121", or "Aron oxetane OXT-211". "Aron oxetane OXT-221" and "Aron oxetane OXT-212" (above, East Asia Synthetic Co., Ltd.). These propylene oxides are generally contained in the curable epoxy resin composition in a ratio of 5 to 95% by weight, preferably 30 to 70% by weight.

The polyol is preferably an acidic group other than the phenolic hydroxyl group, and examples thereof include a polyol compound having no functional group other than a hydroxyl group, a polyester polyol compound, a polycaprolactone polyol compound, and a phenolic hydroxyl group. Polyol compound, polycarbonate polyol, and the like. The molecular weight of these polyols is generally 48 or more, preferably 62 or more, more preferably 100 or more, and most preferably 1,000 or less. These polyols are hardenable The epoxy resin composition is generally contained in a ratio of 50% by weight or less, preferably 30% by weight or less.

The active energy ray-curable adhesive may further incorporate an ion trapping agent, an antioxidant, a chain shifting agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a leveling agent, a plasticizer, an antifoaming agent, and the like. . The ion scavenger may, for example, be an inorganic compound such as a powdery lanthanum, a lanthanide, a magnesium, an aluminum, a calcium, a titanium or a mixed system thereof. The antioxidant may, for example, be a hindered phenol antioxidant.

The active energy ray-curable adhesive can be used as a solventless adhesive which does not substantially contain a solvent component. However, each coating method has an optimum viscosity range, and therefore, a solvent may be contained for viscosity adjustment. The solvent is preferably an organic solvent such as a hydrocarbon represented by toluene or an ester represented by ethyl acetate, for example, which does not lower the optical performance of the polarizing film and dissolves the epoxy resin composition. The viscosity of the active energy ray-curable adhesive used in the present invention is, for example, in the range of about 5 to 1000 mPa ‧ s, preferably 10 to 200 mPa ‧ s, more preferably 20 to 100 mPa ‧ s.

In the examples shown in Fig. 6, Fig. 7, Fig. 8, and Fig. 9, the transparent films 2 and 3 which are continuously drawn in a state of being wound into a roll are used by the adhesive applicator 11 and 12 The active energy ray-curable adhesive is applied to one side, respectively. The method of applying the coating agent to the transparent film is not particularly limited, and for example, various coating methods such as a doctor blade, a wire bar, a die applicator, a comma applicator, and a gravure coater can be used. . Here, if the degree of freedom, the width, and the like of the film coating, the pass line, and the like are considered, the adhesive application devices 11, 12 are preferably gravure rolls. The commercially available coating device may, for example, be MCD (Micro Chamber doctor) manufactured by Fuji Machinery Co., Ltd., or the like.

Applying an adhesive to the adhesive application devices 11 and 12 using a gravure roll The thickness (coating thickness) of the applied adhesive is preferably from 0.1 to 10 μm, more preferably from 0.2 to 4 μm. The coating thickness of the subsequent agent is adjusted by the ratio of the speed of the gravure roll to the linear speed of the transparent film. In general, the coating thickness of the adhesive can be adjusted to about 0.1 to 10 μm by adjusting the draw ratio (speed/line speed of the gravure roll) to 0.5 to 10. More specifically, the linear speed of the transparent films 2, 3 is 10 to 100 m/min, and the gravure roll is rotated in the opposite direction to the conveying direction of the transparent films 2, 3 so that the speed of the gravure roll is 5 to 1000 m/min. The coating thickness of the adhesive can be adjusted to about 0.1 to 10 μm.

The subsequent agent is generally adjusted to a specific temperature within a range of 15 to 40 ° C ± 5 ° C (for example, a specific temperature of 30 ° C, 30 ° C ± 5 ° C), preferably ± 3 ° C, preferably Coating in an environment of ±1 °C.

[3] fitting step

Next, a large feature of the present invention is that, as described above, the surface of the transparent film coated with the active energy ray-curable adhesive is adhered to the bonding roller and adhered to one side or double of the polarizing film. Face, make a laminate. In the method for producing a polarizing plate of the present invention, the transparent film may be bonded only to either side of the polarizing film or may be bonded to both surfaces. When laminated on both sides, the respective transparent films may be the same or different types.

In the examples shown in Fig. 6, Fig. 7, Fig. 8, and Fig. 9, the transparent films 2 and 3 which are continuously drawn in a state of being wound into a roll are used by the adhesive applicator 11 and 12 The active energy ray-curable adhesive is applied to one side, respectively. Then, in the same manner as the transparent films 2 and 3 described above, the laminated body 4 in which the transparent films 2 and 3 are superposed on each other on the both sides of the polarizing film 1 which is continuously pulled out by the bonding rolls 5a and 5b, respectively, can be formed. . In this case, in the method of manufacturing a polarizing plate of the present invention, an obstacle 6 (Fig. 6) or a suction means 7 (Fig. 7 and Fig. 8) or a blowing or suction means 8 (Fig. 9) are provided. For example, as described with reference to FIGS. 1 , 2 , 3 , and 5 . Further, when the transparent film is bonded to both surfaces of the polarizing film, the angle in the range of ±3° with respect to the surface perpendicular to the pressing direction of the bonding roller is preferably an angle within a range of ±1°. Preferably, the polarizing mold is conveyed between the bonding rolls in such a manner as to overlap the surface perpendicular to the pressing direction. In this way, the polarizing film and the transparent film are in contact with each other before the roller is attached, and no air bubbles are generated.

Further, in the examples shown in Fig. 6, Fig. 7, Fig. 8, and Fig. 9, it is shown that the adhesive is uniformly applied to one surface of the transparent films 2 and 3, and the coating is applied to the transparent films 2 and 3. The surface of the adhesive film is overlapped with the polarizing film 1 and bonded by the bonding rollers 5a and 5b. However, the adhesive may be uniformly applied to both surfaces of the polarizing film 1, and the polarizing film 1 may be coated. The surface of the subsequent agent overlaps the transparent films 3 and 2 and is bonded by the bonding rolls 5a and 5b.

In the present invention, the rotational speed of the bonding roller is linked to the linear velocity. The linear velocity is generally from 10 to 100 m/min, but the productivity is preferably 20 m/min or more, more preferably 30 m/min or more. The method of reducing the wind pressure in the region before the bonding of the present invention, especially when the line speed is fast, is effective.

In the present invention, one of the pair of bonding rollers 5a, 5b may have a tapered shape (that is, the radius of the central portion is larger than the radius of the end portion) from the central portion to the end portion (taper) The crown roller of the outer peripheral shape. In this case, the non-coronal roller of the non-coronal roller is preferably a flat flat roll having a substantially uniform diameter.

The shape of the crown roller is pressed in the laminating step, and the interval between the crown roller and the flat roller should be substantially uniform. Here, the interval between the crown roller and the flat roller refers to the interval between the outer circumference of the crown roller and the flat roller in the cross section including the shaft of the crown roller and the shaft of the flat roller. also, Generally, the crown roller and the flat roller are arranged such that the shaft of the crown roller and the shaft of the flat roller are parallel in a state where the pressing is not performed.

For example, when the bonding roller 5a is a flat roller made of metal and the bonding roller 5b is a crown roller made of rubber, pressure is applied to the bearing member of the flat roller toward the direction of the crown roller. In the state in which the pressing is performed, the crown roller system is deflected. However, if the shape of the crown roller is designed such that the interval between the crown roller and the flat roller is substantially uniform, the laminate can be uniformly pressed. Further, the same effect can be obtained when the crown roller is pressed in the direction of the flat roller. Further, both the crown roller and the flat roller can be pressed in a direction in which they approach each other.

When the crown roller is used, the ratio of the difference between the diameter of the central portion and the diameter of the end portion is preferably 0.0020 to 0.0500% with respect to the length of the crown roller (the length in the axial direction). More preferably, it is 0.0020 to 0.020%. In general, in such a ratio range, the shape of the crown roller can be designed such that the interval between the crown roller and the flat roller is uniform in the state of being pressed in the bonding step.

Further, when the crown roller is used, the tapered outer peripheral shape is preferably an arc shape. Here, the arcuate outer circumferential shape of the crown roller means that the cross section of the surface including the axis of the tapered outer peripheral shape of the crown roller is an arc shape. When the shaft member of the flat roller is pressed in the bonding step, the flat roller system often has a shape in which the outer peripheral shape is curved into an arc shape, so that the outer peripheral shape of the crown roller is formed to have the same degree of curvature. The radius of the arc is uniform, and the interval between the pressing rollers (the crown roller and the flat roller) can be made uniform, and the polarizing film and the transparent film can be bonded to each other with uniform pressure.

The diameter of the bonding roller is not particularly limited, but the diameter of the flat roller is preferably 50 to 400 mm. Further, the diameter of the end portion of the crown roller is preferably 50 to 400mm. Moreover, the diameters of the pair of bonding rollers may be the same or different. The width of the bonding roller is 300 to 3000 mm.

The pressure of the pressing force is not particularly limited. However, when a metal roller and a rubber roller are used, the instantaneous pressure in a two-piece Prescale (trade name) (for ultra low pressure) manufactured by Fuji Film is preferably 0.5 to 3.0 MPa. More preferably 0.7 to 2.3 MPa. In the present invention, the pressure for the pressing force of the bonding roller is generally applied to the bearing members of the both ends of the bonding roller.

The material of the bonding roller may be, for example, metal or rubber. Preferably, one of the pair of bonding rollers is a metal roller, and the other is a rubber roller. Further, it is more preferable that the flat roller is made of metal and the crown roller is made of rubber.

In the conventional bonding roller, the bonding roller on the upper side of the pressing force is generally made of rubber, and the lower bonding roller is made of metal. This is to control the rotation speed by attaching a drive motor to the lower bonding roller, so that the bonding roller on the lower side is not deformed by the metal roller when the pressing roller is pressed at the lower side, and the bonding roller is easy to be fitted. The weekly speed is maintained at a constant rate. However, in this case, in order to facilitate curl adjustment, it is preferable that the bonding roller (upper side) is made of metal, and the other (lower side) bonding roller is made of rubber.

The base material of the metal roll can be made of various known materials, but is preferably stainless steel, and more preferably SUS 304 (stainless steel containing 18% of Cr and 8% of Ni). The surface of the metal roller is preferably subjected to a chromium plating treatment.

The material of the rubber roller is not particularly limited, and examples thereof include NBR (nitrile rubber), Titan, urethane, polyfluorene oxide, EPDM (ethylene-propylene-diene rubber), and the like, and are preferably NBR or Titan. , urethane. The hardness of the rubber roller is not particularly limited and is generally 60 to 100°, preferably 85 to 95°. Further, the hardness of the rubber roller can be measured using a hardness meter according to JIS K 6253. Commercially available durometers can be used, for example, Asuka Rubber hardness tester "Type-A" made by the company. Specifically, when the surface is used such as a stick, the surface resistance of the rubber roller is measured by a durometer.

6 , 7 , 8 , and 9 show an example in which a pair of bonding rollers are bonded to each other. However, the present invention is not limited thereto, and may be used to hold a pair of bonding rollers. The method further comprises the configuration of a pair of rollers.

[4] Step of irradiating the active energy line on the laminate

In the subsequent step, the laminate obtained by the above method is irradiated with an active energy ray to obtain a polarizing plate. In the examples shown in Fig. 6, Fig. 7, Fig. 8, and Fig. 9, the laminate 4 is then conveyed while being adhered to the outer peripheral surface of the roller 13. In the examples shown in Fig. 6, Fig. 7, Fig. 8, and Fig. 9, the first active energy ray irradiation devices 14, 15 provided at positions facing the outer peripheral surface of the roller 13 are further advanced. In the transport direction, the second and subsequent active energy ray irradiation devices 16 , 17 and 18 and the nip roll 19 for transport are provided in the same manner as the above-described one in the transport direction downstream. In this way, the laminate 4 is adhered to the outer peripheral surface of the roller 13 while being conveyed, and the active energy ray is irradiated from the first active energy ray irradiation devices 14 and 15 toward the outer peripheral surface of the roller 13 to form an adhesive. Polymerization hardening. Further, the second and subsequent active energy ray irradiation devices 16, 17, and 18 disposed on the downstream side in the transport direction are devices for completely curing and curing the adhesive, and may be added or omitted as needed. Finally, the laminated body 4 is formed by the conveyance nip roller 19, and the polarizing plate is formed, and it is wound up as the winding roller 20.

The roller 13 is formed by a mirror-finished convex curved surface of the outer peripheral surface, and is conveyed while the laminate 4 is adhered to the surface thereof, and the adhesive is polymerized and hardened by the active energy ray irradiation devices 14 and 15 in the process. When the adhesive is polymerized and hardened, and the laminate 4 is sufficiently adhered, the diameter of the roller 13 is not particularly limited. The roller 13 can also be driven or rotationally driven by the action of the production line of the laminate 4, or the laminate 4 can be fixed on the surface. slide. Further, when the roller 13 is subjected to polymerization hardening by irradiation with an active energy ray, it can also function as a cooling roller for radiating heat generated by the laminated body 4. At this time, the surface temperature of the roller 13 acting as a cooling roller is preferably set to 4 to 30 °C.

The light source used for the polymerization hardening of the adhesive agent by irradiation with the active energy ray is not particularly limited, but is preferably a light source having a light-emitting distribution at a wavelength of 400 nm or less. Such a light source may be, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, or a metal halide lamp.

The light irradiation intensity of the active energy ray-curable adhesive is not particularly limited as long as it is determined by the composition of each adhesive, but is preferably 10 to 5000 mW/cm ² . If the light irradiation intensity of the resin composition is less than 10 mW/cm ² , the reaction time is too long. If it exceeds 5000 mW/cm ² , the heat radiated from the lamp and the heat generated during the polymerization of the composition may cause an adhesive. The yellowing of the epoxy resin composition or the like of the constituent material or the deterioration of the polarizing film. Further, the irradiation intensity is preferably the intensity in the wavelength region effective for activation of the photocationic polymerization initiator, more preferably the intensity in the wavelength region of 400 nm or less, and the intensity in the wavelength region of the optimum wavelength of 280 to 320 nm. .

The irradiation time of the active energy ray-curable active energy ray-curable adhesive is controlled for each hardened composition, and is not particularly limited. However, the cumulative light amount as a product of the irradiation intensity and the irradiation time is set to 55 mJ/cm ^{2 .} Above, it is preferably 55 to 5000 mJ/cm ² . When the cumulative amount of the above-mentioned adhesive is less than 55 mJ/cm ² , the generation of the active species derived from the initiator is insufficient, and the hardening of the adhesive is insufficient, and the wave relaxation defects at both ends of the polarizing plate may be generated. . In addition, when the cumulative light amount exceeds 5000 mJ/cm ² , the irradiation time becomes extremely long, which is disadvantageous for productivity improvement. At this time, whether or not the cumulative light amount of the wavelength region (UVA (320 to 390 nm) or UVB (280 to 320 nm), etc.) needs to be different depending on the combination of the film or the adhesive used.

In the present invention, the laminate is irradiated with an active energy ray to cure and cure the adhesive, but it may be cured by polymerization by heating.

When the active energy ray is ultraviolet ray, in the step of irradiating the laminated body 4 with the active energy ray, it is preferable to apply the tension of the laminated body 4 to the longitudinal direction (transport direction) by 100 to 800 N/m while making the irradiation time 0.1. The laminate 4 is conveyed at a line speed of seconds or more. Further, the irradiation intensity of ultraviolet rays is preferably 10 mW/cm ² or more.

Further, when the accumulated light amount of the active energy ray of the active energy ray irradiation devices 14 and 15 is insufficient, it is preferable to further provide the second and subsequent active energy ray irradiation devices 16, 17, and 18, and additionally irradiate the active energy ray to promote the laminate. 4 of the hardening of the adhesive. The cumulative light amount in all of the steps is 55 mJ/cm ² or more, and is preferably set to 55 to 5000 mJ/cm ² . As such, in the step of irradiating the active energy ray, the irradiation of the active energy ray is preferably carried out in plural times.

In order to securely cure the adhesive at the end of the polarizing plate (laminate), for example, a method in which the Light Hammer 10 manufactured by Fusion, an electrodeless D-bulb lamp, is arranged so as to straddle the film.

The ratio of the active energy ray-curable resin hardening, that is, the reaction rate is preferably 90% or more, more preferably 95% or more.

(Polarizing plate winding step)

The tension of the take-up laminate (polarizing plate) 4 is not particularly limited, but is preferably in the range of 30 to 150 N/cm ² , more preferably in the range of 30 to 120 N/cm ² . When the tension of the take-up laminate 4 is less than 30 N/cm ² , when the roll of the long roll is transferred, there is a tendency to cause a roll-off offset. When the roll is larger than 150 N/cm ² , the roll is stretched and stretched, and slack is likely to occur. The tendency.

Further, the longer the winding length is, the more the winding tension is likely to occur when the same tension is applied (it is difficult to return to a flat state when pulled out), so that the tension can be continuously or stepwise while the polarizing plate is wound around the core. reduce. Even in the method of reducing the tension by using a so-called cone as described above, the tension at this time is 150 N/cm ² or less.

The length of the polarizing plate taken up from the core is not particularly limited, but is preferably 100 to 4000 m.

The cylindrical core preferably has a diameter of 6 to 12 inches. The larger the diameter of the core, the better, preferably 11 inches, 12 inches, etc. If the diameter is too large, there is a tendency to be difficult to transfer or store.

Since the material of the cylindrical core is used in a clean room, it is difficult to dust itself, and it is not particularly limited as long as it can secure the appropriate strength of the polarizing plate having a wide width, but FRP (glass fiber) can be selected. Reinforced plastic).

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited to the examples.

In the present embodiment, a polarizing plate obtained by laminating a composite film laminate containing one polarizing film and one transparent film was produced by using the apparatus shown in Fig. 3.

<Example 1>

A polarizing film produced by using a polyvinyl alcohol film "Vinylon VF-PS #7500" (manufactured by Kuraray Co., Ltd.) and a cellulose ester resin film "KC4UYW" (manufactured by Konica Minolta Opto Co., Ltd.) are interposed with a water-based adhesive. Then, a composite film laminate having a total thickness of 135 μm, which is a surface protective film "NBO-0424" (manufactured by Fujimori Industrial Co., Ltd.) to which an adhesive layer is attached, is laminated on the KC4UYW surface. In addition, a cellulose acetate-based resin film "KC4CR-1" having a phase difference characteristic of 40 μm (Konica Minolta Opto) was prepared. system). An epoxy resin composition (containing a cationic polymerization initiator) coated with an ultraviolet curing type adhesive agent on one surface of a cellulose acetate-based resin film "KC4CR-1" having a phase difference characteristic by using an adhesive application device "KR series" (made by ADEKA, viscosity: 44mPa‧s). At this time, the linear velocity of the polarizing film laminate in the adhesive application device was set to 40 m/min, and the gravure roll was rotated in the opposite direction to the direction in which the laminate was conveyed, so that the thickness of the adhesive layer was about 1.0 μm. .

Next, a laminate in which the polarizing film surface of the composite film laminate is laminated to the adhesive applied to the cellulose acetate resin film having phase difference characteristics is laminated at a linear velocity of 40 M/min. The nip roller (bonding roller) of one of the diameters of 250 mm was pressed at a pressure of about 1.5 MPa, and the cellulose acetate-based resin film having the phase difference characteristics described above was bonded to the polarizing film.

A suction device of Fig. 3 is provided between the cellulose acetate-based resin film having phase difference characteristics and the polarizing film before the pair of nip rolls are bonded, and the wind pressure in the region between the films is reduced. The amount of pressure reduction in the apparatus at this time was 2.0 kPa.

The laminate in which the above two types of films were bonded was transferred at a linear velocity of 40 m/min, and the total accumulated light amount (the cumulative amount of light irradiation intensity in a wavelength region of a wavelength of 280 to 320 nm) was about 100 mJ/cm ² (measuring device: Ultraviolet (UVB) of the measured value of UV Power Puck II manufactured by Fusion UV.

After the obtained polarizing plate was evaluated, almost no bubbles were observed between the polarizing film and the cellulose acetate-based resin film having the phase difference characteristics. The results are shown in Table 1.

<Example 2>

A polarizing plate was produced in the same manner as in Example 1 except that the linear velocity was 25 m/min, and the amount of pressure reduction in the suction device of Fig. 3 was 0.6 kPa.

After evaluating the obtained polarizing plate, the polarizing film and the acetic acid imparting phase difference characteristics There are few bubbles between the cellulose resin films. The results are shown in Table 1.

<Comparative Example 1>

A polarizing plate was produced in the same manner as in Example 1 except that the suction device was not provided and the suction was not performed.

After the obtained polarizing plate was evaluated, a large number of bubbles were observed in the entire surface between the polarizing film and the cellulose acetate-based resin film having the phase difference characteristics. The results are shown in Table 1.

From the above results, it was found that the generation of air bubbles in the polarizing plate can be suppressed by reducing the wind pressure in the region between the films before bonding.

(industrial availability)

The polarizing plate of the present invention can be effectively applied to various display devices mainly including liquid crystal display devices.

1‧‧‧ polarizing film

2, 3‧‧‧ transparent film

4‧‧‧Layer

5a, 5b‧‧‧ fitting roller

6‧‧‧ obstacles

Claims (3)

A method for producing a polarizing plate, comprising the steps of: performing a dyeing treatment, a boric acid treatment, and a uniaxial stretching treatment on a polyvinyl alcohol-based resin film to form a polarizing film; and applying active energy ray hardening on one side of the transparent film; a step of forming a type of adhesive; and superposing the polarizing film on the surface of the transparent film coated with the adhesive; and sticking it with a bonding roller to bond the transparent film to one side or double of the polarizing film a step of preparing a laminate; and a step of irradiating the laminate with an active energy ray to form a polarizing plate; wherein the step of fabricating the laminate is to reduce the distance between the polarizing film and the transparent film before bonding The wind pressure in the area is carried out. The method for producing a polarizing plate according to claim 1, wherein the air between the polarizing film and the transparent film before bonding is adhered by the bonding roller, and the bonding is reduced before the bonding. The wind pressure of the region between the polarizing film and the transparent film. The method for producing a polarizing plate according to the first or second aspect of the invention, wherein, in the step of producing the laminate, the linear velocity at the time of bonding is 10 m/min or more.