JP4516391B2 - Polarizing film manufacturing method and polarizing film manufacturing apparatus - Google Patents

Description

  The present invention relates to an image display device such as a liquid crystal display device (LCD), an electroluminescence display device (ELD), a plasma display panel (PDP), and a field emission display (FED), and particularly polarized light used for a liquid crystal display device. It is related with the manufacturing method of a film, and also the polarizing film obtained by this manufacturing method. The present invention also relates to an optical film obtained by laminating an optical layer on the polarizing film, a polarizing plate, and the polarizing film or an image display device having the optical film.

  A polarizing film used for an image display device (particularly a liquid crystal display device) is required to have a high transmittance and a high degree of polarization in order to provide a bright image with good color reproducibility. Conventionally, such a polarizing film is obtained by dyeing a polyvinyl alcohol (PVA) film or the like with a dichroic substance such as iodine having a dichroism or a dichroic dye, and orienting it by a method such as uniaxial stretching. Manufactured by.

In recent years, with the increase in demand for liquid crystal display devices, the demand for polarizing films used for the liquid crystal display devices has increased, and in addition, it has excellent high-level optical characteristics and in-plane uniformity without defects such as unevenness and foreign matter. There is a demand for a polarizing film (see, for example, Patent Document 1). In order to increase production while maintaining the high-level optical characteristics of this polarizing film, it has been attempted to increase the current production facilities or increase the number of polarizing films using wider films. Yes. However, with these methods, for example, the labor and cost of adding equipment are enormous, and the production of wide films is difficult, and the conventional methods deteriorate optical characteristics and increase unevenness and defects. I know. Therefore, there is a demand for a method for easily increasing the production amount without deteriorating optical characteristics. Until now, a method of laminating and stretching a film has been disclosed as such a method (see, for example, Patent Document 2). However, since this method is specialized only for the stretched portion, this method is treated. It has been difficult to apply as it is to a series of manufacturing processes having a bath.
JP 2001-290027 A JP 2002-333520 A

  An object of the present invention is to provide a simple method for producing a polarizing film in a method for producing a polarizing film produced through at least one treatment bath without deteriorating optical properties such as transmittance and degree of polarization. . Moreover, it aims at providing the polarizing film obtained by this manufacturing method, the optical film which laminated | stacked the optical layer on this polarizing film, and the image display apparatus using these polarizing films or an optical film.

  The inventors of the present invention have intensively studied to examine the above-mentioned problems. As a result, they have found that the above object can be achieved by the following method for producing a polarizing plate, and have completed the present invention.

  The present invention provides a polarizing film having a dyeing treatment step and a stretching treatment step, wherein the polarizing film is produced by immersing a plurality of films simultaneously in at least one treatment bath without contacting them. It is a manufacturing method of a film. At this time, the number of the raw film immersed simultaneously is preferably 2 to 4. Moreover, as a manufacturing method of the polarizing film at this time, after dyeing a PVA-type film with a dichroic substance in the dyeing | staining process, it is preferable to uniaxially stretch in an extending | stretching process.

  Furthermore, the present invention provides a polarizing film obtained by the method for producing a polarizing film, an optical film in which an optical layer is laminated on at least one surface of the polarizing film, a liquid crystal panel in which the polarizing film or the optical film is laminated, and the polarizing film The present invention relates to an image display device having a film, an optical film, or a liquid crystal panel.

  The liquid crystal panel and the image display device are preferably manufactured by an in-house manufacturing method.

  Moreover, this invention relates to the polarizing film manufacturing apparatus which has a processing bath provided with the holder for conveyance which conveys the several film for immersing several film in the same processing bath simultaneously, 2-4 sheets It is preferable that it is a manufacturing apparatus provided with the holder for conveyance which conveys this film.

  According to the present invention, by simultaneously processing a plurality of films in the manufacturing process of a polarizing film, the production amount per unit time can be increased more easily without deteriorating optical properties. The method of the present invention is a manufacturing apparatus having a wide treatment bath for manufacturing a wide polarizing film even when compared with a polarizing film manufactured using a wide film as has been attempted in the past. 3 and FIG. 4 are used to produce a polarizing film from a plurality of films, so that not only the optical characteristics and surface conditions that have been problematic when widened are produced. The production amount per unit time can be manufactured to the same extent as when a wide film is manufactured. That is, it is possible to obtain a large amount of a polarizing film having more excellent optical characteristics. Furthermore, in the manufacturing process of the polarizing film, even if the concentration in the treatment bath slightly changes, the optical characteristics change greatly, but according to the manufacturing method of the present invention, by processing a plurality of films simultaneously, Since a desired production amount can be obtained in a short time, a polarizing film having almost the same characteristics can be produced in a large amount without being affected by the change over time of contained substances and concentration in the treatment bath. Therefore, when the manufacturing method of the present invention is used, it is possible to easily cope with an increase in the production amount of a polarizing film accompanying an increase in demand for image display devices.

  The present invention is particularly used in the manufacturing process of a polarizing film produced through a dyeing process in which a film is immersed in a treatment bath containing a dichroic substance and a stretching process in which the film is uniaxially stretched and oriented. It has been found that by simultaneously treating a plurality of films in one treatment bath, the production amount of a polarizing film can be easily increased without degrading optical properties.

  As the polarizing film, a raw film made of a polymer film such as a polyvinyl alcohol (PVA) film is generally dyed with a dichroic substance such as iodine or a dichroic dye and uniaxially stretched. A polarizing plate is formed by laminating a transparent protective layer as an optical layer on one side or both sides of the polarizing film.

  The polymer film to be a raw film is not particularly limited, and various types can be used. For example, PVA films (including modified PVA films such as partially formalized PVA films and acetoacetyl group-modified PVA films), polyethylene terephthalate (PET) films, ethylene / vinyl acetate copolymer films, and the like Examples of hydrophilic polymer films such as partially saponified films and cellulose films include polyene-based oriented films such as PVA dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, since it is excellent in the dyeability by dichroic substances, such as an iodine, it is preferable to use a PVA-type film.

  The degree of polymerization of the polymer film material is generally 500 to 10,000, preferably 100 to 6,000, and more preferably 1,400 to 4,000. . Furthermore, in the case of a saponified film, the saponification degree is preferably 75 mol% or more, more preferably 98 mol% or more, and more preferably in the range of 98.3 to 99.8 mol%.

  When a PVA-based film is used as the polymer film, the PVA-based film can be formed by any method such as a casting method in which a stock solution dissolved in water or an organic solvent is cast, a casting method, an extrusion method, or the like. Can be used as appropriate. As the polymer film, a film having a retardation value of 5 nm to 100 nm is preferably used. Moreover, in order to obtain a polarizing film with uniform in-plane, it is preferable that the retardation variation in the PVA-based film is as small as possible, and the in-plane retardation variation of the PVA-based film as the initial raw film is at a measurement wavelength of 1000 nm. It is preferably 10 nm or less, and more preferably 5 nm or less.

  As an optical characteristic of the polarizing film obtained by the production method of the present invention, the single transmittance when measured with a polarizing film or a polarizing plate is preferably 40% or more, more preferably 43% or more. Preferably, it is particularly preferably in the range of 43.3 to 45.0%. Moreover, it is preferable that the orthogonal transmittance measured by superimposing two polarizing films or polarizing plates so that the absorption axes of the two polarizing films are 90 ° with each other is smaller, and practically 0. It is preferably 0.000% or more and 0.050% or less, and more preferably 0.030% or less. Furthermore, the degree of polarization is preferably 99.90% or more and 100% or less in practice, and particularly preferably 99.93% or more and 100% or less.

  The production of the polarizing film requires a dyeing process for dyeing a raw film such as a PVA film with a dichroic material and a stretching process for controlling the orientation state of the dichroic material. In the present invention, the order of these is not particularly limited. However, a method in which a raw film is impregnated with a dichroic material and then stretched and oriented is preferable because a polarizing film having desired optical properties can be obtained stably. The stretching at this time is preferably uniaxial stretching, but is not limited to this. If the dichroic material can be in a desired orientation state, a plurality of biaxial stretching and stretching directions are appropriately controlled. A stretching method such as sequential sequential stretching is also preferably used. The stretching method of the polarizing film is generally divided into a dry stretching method and a wet stretching method, and the present invention can be applied without being limited to these stretching methods as long as it is a production method having a treatment bath. Since the present invention is characterized by being manufactured by immersing in the same treatment bath, it is preferable to use a wet stretching method in which stretching is performed in the treatment bath. In particular, when a plurality of films are immersed in the same treatment bath, the films need not be in contact with each other. If the films are in contact with each other, problems such as displacement and damage due to swelling and stretching of the film, sticking between films, and uneven dyeing occur.

  As a method for producing a polarizing film by the wet stretching method, an appropriate method can be used depending on the conditions. For example, the polymer film as a raw fabric film is subjected to a swelling treatment step, a dyeing treatment step, a crosslinking treatment. A method of manufacturing by a series of manufacturing steps as shown in FIG. 2 consisting of a process, a stretching process, a water washing process and a drying process is common. In this manufacturing process shown in FIG. 2, in each of these processing steps excluding the drying processing step, each processing is performed while the film is immersed in a bath made of various solutions. The order, number of times, and presence / absence of each treatment of swelling, dyeing, crosslinking, stretching, washing and drying in each treatment step are not particularly limited, and several treatments may be performed simultaneously in one treatment step. Some processing may not be performed. For example, the stretching process may be performed after the dyeing process, or may be performed simultaneously with the swelling or the dyeing process, or may be performed after the stretching process. Moreover, as an extending | stretching process, an appropriate method can be used without being limited. For example, when extending | stretching using a roll, the method of extending | stretching by the circumferential speed difference between rolls is used preferably. Furthermore, additives such as boric acid, borax, or potassium iodide may be appropriately added to each treatment, and the polarizing film according to the present invention may contain boric acid, zinc sulfate, zinc chloride, potassium iodide, etc. as necessary. May be included. Furthermore, in some of these processes, the film may be stretched in the flow direction or the width direction as appropriate, and a water washing process may be performed for each process.

  Moreover, in this invention, in at least 1 of each process process (each process bath) which manufactures the said polarizing film, a polarizing film is produced by processing a several sheets of film simultaneously. As a film processing (immersion) method at this time, the form of the film, the number of sheets, and the number of treatment baths to which a plurality of sheets are immersed are not limited, and can be appropriately designed as necessary. In the drying process, a plurality of films may be processed simultaneously as necessary, or may be processed separately under different conditions.

  As the form of the treatment bath, for example, as shown in FIGS. 3 to 7, a plurality of films are horizontally (FIGS. 3 and 7) or vertically (FIG. ) And combinations thereof (FIG. 6), and a mode in which a plurality of films are processed with a film transporting holder smaller than the number of processed sheets (FIG. 4) can be used. At this time, the number of films to be processed is not particularly limited as long as it is 2 sheets or more, but it is about 2 to 4 sheets from the viewpoint of the simplicity of the manufacturing apparatus and the stability of the processing bath. preferable. When the number of sheets immersed in the same treatment bath is too large, it is not preferable because a significant design change of the apparatus is required and it is difficult to stabilize the treatment solution concentration in the treatment bath. Moreover, although the example which arrange | positions a film horizontally with respect to the bottom of a processing bath was shown above, by adjusting the tension at the time of the design of a processing bath and film conveyance, in the state which was perpendicular | vertical or inclined with respect to the bottom of a processing bath. A film may be conveyed.

  The form of this treatment bath may be different for each treatment step. In addition, by simultaneously processing a plurality of films without bringing the films into contact with each other as in the present invention, as shown in FIG. It is also possible to design a manufacturing method that branches from this step into a plurality of steps. Furthermore, in the manufacture of a polarizing film where it is important to design optical characteristics by adjusting the conditions of each processing step, the dyeing time of each film to be processed simultaneously by appropriately changing the processing step design using the present invention Since various conditions such as the draw ratio and the like can be changed, multi-product simultaneous production is possible in the same space as before.

  In the manufacturing method exemplified above, each processing step except for the drying processing step is performed in a processing bath filled with appropriate various solutions (processing solutions), but the present invention is capable of processing a plurality of sheets simultaneously in this processing bath. Is to do. As this processing bath, it is necessary to be equipped with the bathtub for storing various solutions, and the holder for conveying a film.

The bath of the treatment bath can be used without particular limitation as long as it is sturdy without being affected by the solution required for each treatment, and the material thereof is aluminum, stainless steel or the like. Metal or ceramic is preferably used. Further, the capacity can be appropriately determined according to the necessity, but generally a capacity of about 1 to 200 m ³ is used.

  As a film transporting holder used in the treatment bath, generally, a roll-shaped one is preferably used, but is not limited thereto, and is not limited to a belt conveyor, plate, pinch, clip, or the like. The film transport holder is appropriately used. When the roll is used as a film transporting holder, the tension during film transport can be adjusted by stretching the roll in the peripheral direction, or the film can be stretched in the film flow direction. As the material of the roll surface, a rubber or metal material is preferably used. The shape of the surface also includes a concave shape, a convex shape, and a corrugated shape, and those in which the roll itself is curved are also appropriately used. When the roll is curved in a convex shape at the center, an effect of stretching in the direction perpendicular to the film flow direction (film width direction) can be expected. Furthermore, the surface of the roll subjected to processing such as grooves and embossing is preferably used as necessary.

  One or more film transporting holders must be provided in the treatment bath. As a method for installing the film transporting holder, a plurality of film transporting holders are provided so as to be sandwiched from both sides of the film, or the edge of the film is fixed using a pinch type or clip type film transporting holder. You may provide in the form to hold | maintain. Moreover, you may use several types of holders for film conveyance in the same manufacturing process. The number and type of such film transporting holders can be appropriately determined according to the application, but in the method of the present invention, a roll is used as the film transporting holder, and one piece as shown in FIG. A method of holding a plurality of films on one roll or a method of holding one film on one roll as shown in FIG. 3, FIG. 5, or FIG. 6 is preferably used.

  Next, an example is shown about each processing process of the manufacturing method of the polarizing film by the said wet extending | stretching method.

  As the swelling treatment step, for example, it is immersed in a swelling bath filled with water. As a result, the polymer film is washed with water, and the surface of the polymer film can be cleaned of stains and anti-blocking agents, and the effect of preventing unevenness such as uneven dyeing can be expected by swelling the polymer film. The water is preferably distilled water (pure water), but glycerin, potassium iodide, and the like may be appropriately added to the swelling bath. At this time, the concentration in the swelling bath is preferably 5% by weight or less for glycerin and 10% by weight or less for potassium iodide. The temperature of the swelling bath is preferably in the range of 20 to 45 ° C, more preferably 25 to 40 ° C. The immersion time in the swelling bath is preferably 2 to 300 seconds, more preferably 30 to 240 seconds, and particularly preferably 60 to 180 seconds. Further, the polymer film may be stretched in this swelling bath, and the stretching ratio at that time is about 1.1 to 3.5 times the original length of the polymer film before treatment.

  As the dyeing treatment step, for example, the polymer film is immersed in a dye bath containing a dichroic substance such as iodine in a solution of the dichroic substance to adsorb the dichroic substance to the polymer film, Stain.

  A conventionally known substance can be used as the dichroic substance, and examples thereof include iodine and organic dyes. Organic dyes include, for example, Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue, Direct First orange S, first black, etc. can be used. Of these, iodine is preferably used from the viewpoint of dyeability and orientation.

  One kind of these dichroic substances may be used, or two or more kinds may be used in combination. When using the said organic dye, it is preferable to combine 2 or more types from the point which aims at neutralization of the visible region, for example. Specific examples include congo red and supra blue G, supra orange GL and direct sky blue, or a combination of direct sky blue and first black.

  As the dye bath solution, a solution in which the dichroic substance is dissolved in a solvent can be used. As the solvent, water is generally used, but an organic solvent compatible with water may be further added. According to the present invention, the concentration of the dichroic substance in the dye bath solution is preferably in the range of 0.010 to 2.0% by weight, and in the range of 0.020 to 1.5% by weight. Is more preferable, and 0.025 to 1.0% by weight is particularly preferable. At this time, if the concentration of the dichroic substance is less than 0.010% by weight, it takes a very long time to dye, so that the productivity is remarkably lowered. If it exceeds 2.0% by weight, a desired dyeing amount can be obtained in a very short time, so that it is difficult to control, and unevenness is likely to occur due to a slight malfunction of the apparatus, which is not preferable.

  Further, when iodine is used as the dichroic substance, it is preferable to further add an iodide because the dyeing efficiency can be further improved. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Examples include titanium. Among these, it is preferable to add potassium iodide, and the ratio (weight ratio) of iodine to potassium iodide is preferably in the range of 1: 5 to 1: 100, and 1: 6 to 1:80. More preferably, it is in the range of 1: 7 to 1:70.

  In the present invention, the immersion time of the polymer film in the dye bath is preferably in the range of 10 to 600 seconds, and more preferably in the range of 30 to 300 seconds. At this time, if the immersion time is less than 10 seconds, it is difficult to dye to a desired dyeing amount, and if it exceeds 600 seconds, in addition to the necessity of a huge manufacturing apparatus, the productivity is deteriorated. It is not preferable. Moreover, it is preferable that the temperature of a dyeing bath exists in the range of 5-42 degreeC, and it is more preferable that it exists in the range of 10-35 degreeC. Further, the polymer film may be stretched in this dyeing bath, and the stretch ratio accumulated from the previous step in this stretching is about 1.1 to 4.0 times the original length of the polymer film before treatment. .

  As the crosslinking treatment step, for example, the polymer film that has undergone the dyeing treatment step is immersed in a bath containing a crosslinking agent to be crosslinked. A conventionally known substance can be used as the crosslinking agent. Examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. One kind of these may be used, or two or more kinds may be used in combination. When two or more types are used in combination, for example, a combination of boric acid and borax is preferable. The addition ratio (molar ratio) of boric acid and borax is preferably in the range of 4: 6 to 9: 1, more preferably in the range of 5.5: 4.5 to 7: 3, and 6: 4 is most preferred.

  As the solution of the crosslinking bath, a solution in which the crosslinking agent is dissolved in a solvent can be used. As the solvent, for example, water can be used, but an organic solvent compatible with water may be further included. The concentration of the crosslinking agent in the solution is not limited to this, but is preferably in the range of 1 to 10% by weight, and more preferably 2 to 6% by weight.

  In the crosslinking bath, an iodide may be added from the viewpoint of obtaining in-plane uniform characteristics of the polarizing film. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Titanium may be mentioned, and the content concentration is 0.05 to 15% by weight, more preferably 0.5 to 8% by weight, based on the crosslinking bath solution. Among these, a combination of boric acid and potassium iodide is preferable, and the ratio (weight ratio) of boric acid and potassium iodide is preferably in the range of 1: 0.1 to 1: 3.5, and 1: 0 More preferably, it is in the range of 5 to 1: 2.5.

  The temperature of the crosslinking bath is usually in the range of 20 to 70 ° C. The immersion time of the polymer film is usually in the range of 1 second to 15 minutes, preferably 5 seconds to 10 minutes. Furthermore, as the crosslinking treatment, a method of applying or spraying a solution containing a crosslinking agent may be used, and the polymer film may be stretched in the crosslinking bath. The draw ratio accumulated from the previous step in this drawing is about 1.1 to 4.0 times.

  As the stretching treatment step, for example, in the wet stretching method, the film is stretched to about 2 to 7 times as the cumulative stretching ratio from the previous step while being immersed in a bath.

  The solution of the stretching bath is not particularly limited to this, and for example, a solution to which various metal salts or a compound of iodine, boron or zinc is added can be used. As a solvent of this solution, water, ethanol or various organic solvents are appropriately used. Among these, it is preferable to use a solution containing about 2 to 18% by weight of boric acid and / or potassium iodide. When boric acid and potassium iodide are used simultaneously, the content ratio (weight ratio) of boric acid and potassium iodide is preferably about 1: 0.1 to 1: 4, and 1: 0.5 to 1 : More preferably, the ratio is about 3.

  The temperature of the stretching bath is preferably in the range of 40 to 75 ° C, and more preferably 50 to 62 ° C, for example.

  As the water washing treatment step, for example, by immersing the polymer film in an aqueous solution of a water washing bath, unnecessary residues such as boric acid attached in the previous treatment can be washed away. Iodide may be added to the aqueous solution. For example, sodium iodide or potassium iodide is preferably used as the iodide. When potassium iodide is added to the washing bath, the concentration is usually 0.1 to 10% by weight, preferably 3 to 8% by weight, based on the washing bath solution. Furthermore, the temperature of the washing bath is preferably 10 to 60 ° C, and more preferably 15 to 40 ° C. Moreover, the frequency | count of a washing process is not specifically limited, You may implement several times, You may change the kind and density | concentration of an additive in each washing bath.

  In addition, when pulling up the polymer film from each treatment bath, in order to prevent the occurrence of dripping, a conventionally known liquid break roll such as a pinch roll may be used, or the liquid is scraped off with an air knife, etc. Excess water may be removed by this method.

  As the drying treatment step, an appropriate method such as natural drying, air drying, heat drying or the like can be used, but heat drying is usually preferably used. In heat drying, for example, the heating temperature is preferably about 20 to 80 ° C., and the drying time is preferably about 1 to 20 minutes.

  The final draw ratio (total draw ratio) of the polarizing film produced through the treatment steps as described above is 3.0 to 7.0 times the original length of the polymer film before the treatment. Is preferable, and it is more preferable to be in the range of 5.0 to 6.3 times. If the total draw ratio is less than 3.0 times, it is difficult to obtain a polarizing film having a high degree of polarization, and if it exceeds 7.0 times, the film tends to break.

  Moreover, the manufacturing method of this invention is not limited to the said manufacturing method, It can apply also to the other manufacturing method for obtaining a polarizing film. For example, the above-described dry stretching method or a method of kneading a dichroic material into a polymer film such as polyethylene terephthalate (PET) and then stretching the film after dyeing may be used, or a liquid crystal aligned in a uniaxial direction may be used as a host. As an E type using a dichroic dye as a guest (US Pat. No. 5,523,863, Japanese Patent Publication No. 3-503322), dichroic lyotropic liquid crystal, etc. A method of obtaining a type (US Pat. No. 6,049,428) may be used.

  The thickness of the polarizing film thus produced is not particularly limited, but is preferably 5 to 40 μm. If the thickness is 5 μm or more, the mechanical strength will not be reduced, and if it is 40 μm or less, the optical characteristics will not be reduced, and thinning can be realized even when applied to an image display device.

  The polarizing film according to the present invention can be used by laminating various optical layers in practical use. The optical layer is not particularly limited as long as it satisfies the required optical characteristics. For example, the transparent protective layer provided for the purpose of protection of a polarizing film is mentioned on the single side | surface or both surfaces of a polarizing film. Thus, what laminated | stacked the transparent protective layer on the at least single side | surface of a polarizing film is a polarizing plate. Further, the surface of the transparent protective layer opposite to the surface to be bonded to the polarizing film, or one surface or both surfaces of the polarizing film itself, for the purpose of hard coat treatment, antireflection treatment, sticking prevention, diffusion or antiglare. You may laminate | stack the alignment liquid crystal layer for the purpose of processing, viewing angle compensation, etc., and another film to laminate | stack. Furthermore, as an optical layer, an image such as a polarization conversion element, a reflection plate, a semi-transmission plate, a retardation plate (including a wave plate (λ plate) such as 1/2 or 1/4), a viewing angle compensation film, a brightness enhancement film, etc. There may be mentioned one in which one or more optical films used for forming a display device or the like are laminated. In particular, a polarizing plate in which the polarizing film and the transparent protective layer are laminated, a reflective polarizing plate or a semi-transmissive polarizing plate in which a reflecting plate or a semi-transmissive reflecting plate is laminated, an elliptical polarizing plate in which a retardation plate is laminated or A circular polarizing plate, a wide viewing angle polarizing plate in which a viewing angle compensation layer or a viewing angle compensation film is laminated, or a polarizing plate in which a brightness enhancement film is laminated is preferable. Moreover, when laminating | stacking the said optical layer or the said optical film with a transparent protective layer, the timing may be after bonding with a polarizing film, and may be before bonding with a polarizing film.

  As a material for forming the transparent protective layer provided on one side or both sides of the polarizing film, a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) -Based polymers and polycarbonate-based polymers. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like are also examples of the polymer that forms the transparent protective layer. The transparent protective layer can also be formed as a cured layer of thermosetting or ultraviolet curable resin such as acrylic, urethane, acrylurethane, epoxy, or silicone. Among these, as the transparent protective layer to be bonded to the polarizing film according to the present invention, a triacetyl cellulose film whose surface is saponified with alkali or the like is preferable.

  Moreover, as a transparent protective layer, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007), for example, (A) thermoplastic resin which has a substituted and / or unsubstituted imide group in a side chain, B) A resin composition containing a thermoplastic resin having a substituted and / or unsubstituted phenyl group and a nitrile group in the side chain. Specific examples thereof include a film of a resin composition containing an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used.

  Although the thickness of a transparent protective layer is not specifically limited, Generally it is 500 micrometers or less, and 1-300 micrometers is preferable. In particular, the thickness is more preferably 5 to 200 μm. Moreover, it is preferable that the surface of the transparent protective layer is saponified with an alkali or the like from the viewpoints of polarization characteristics, durability, and adhesion characteristics.

  Moreover, it is preferable that a transparent protective layer has as little coloring as possible. Accordingly, the retardation value in the film thickness direction (Rth) = (nx−nz) × d (where nx is the main refractive index in the film plane, nz is the refractive index in the film thickness direction, and d is the film thickness). ) Is preferably used, and the transparent protective layer having a value of −90 nm to +75 nm is preferably used, and by using this, the coloring (optical coloring) of the polarizing plate due to the transparent protective layer can be reduced. Furthermore, Rth is more preferably −90 to +75 nm, and particularly preferably in the range of −80 nm to +60 nm.

  When laminating the transparent protective layer on both sides of the polarizing film, those having different characteristics may be used on each side. Examples of the characteristics include, but are not limited to, thickness, material, light transmittance, tensile elastic modulus, and presence / absence of an optical layer.

  The hard coat treatment is applied for the purpose of preventing damage to the polarizing film or the polarizing plate surface in which the polarizing film and the transparent protective layer are laminated. For example, an appropriate ultraviolet curable resin such as acrylic or silicone is used. It can be formed by a method of adding a cured film excellent in hardness, sliding property, etc. to the surface of the transparent protective layer. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. Further, the anti-sticking treatment is performed for the purpose of preventing adhesion with an adjacent layer.

  The anti-glare treatment is performed for the purpose of preventing external light from being reflected on the surface of the polarizing plate and obstructing visual recognition of the light transmitted through the polarizing plate. For example, it can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective layer by an appropriate method such as a roughening method by a sandblasting method or an embossing method or a blending method of transparent fine particles. The fine particles to be included in the formation of the surface fine concavo-convex structure are made of, for example, silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, or the like having an average particle diameter of 0.5 to 50 μm, and conductive. Transparent fine particles such as inorganic fine particles that can be provided with organic fine particles made of a crosslinked or uncrosslinked polymer are used. When forming the surface fine uneven structure, the amount of fine particles used is generally about 2 to 70 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The optical layers such as the antireflection layer, the antisticking layer, the diffusion layer and the antiglare layer can be provided on the transparent protective layer or the polarizing film itself, and separately provided separately from the transparent protective layer. You can also.

  When the polarizing film and the transparent protective layer are bonded via an adhesive layer, the bonding process is not particularly limited. For example, an adhesive made of a vinyl polymer, boric acid, borax, or glutar It can be carried out via an adhesive comprising at least a water-soluble crosslinking agent of a vinyl alcohol polymer such as aldehyde, melamine or oxalic acid. This adhesive layer can be formed as an aqueous solution coating / drying layer or the like, but when preparing the aqueous solution, other additives and a catalyst such as an acid can be blended as necessary. In particular, when a polyvinyl alcohol-based polymer film is used as the polarizing film, it is preferable from the viewpoint of adhesiveness to use an adhesive made of polyvinyl alcohol.

  A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Therefore, there is an advantage that the liquid crystal display device can be thinned easily. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer or the like as necessary.

  Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or a vapor deposition film made of a reflective metal such as aluminum on one surface of a matte transparent protective layer as necessary. . Moreover, the transparent protective layer contains fine particles to form a surface fine concavo-convex structure, and a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. Moreover, the transparent protective layer containing fine particles has an advantage that incident light and its reflected light are diffused when passing through it and light and dark unevenness can be further suppressed. The reflective layer of the fine concavo-convex structure reflecting the surface fine concavo-convex structure of the transparent protective layer is formed by an appropriate method such as a vapor deposition method such as a vacuum vapor deposition method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of directly attaching to the surface of the transparent protective layer.

  The reflection plate can be used as a reflection sheet in which a reflection layer is provided on an appropriate film according to the transparent film, instead of the method of directly applying to the transparent protective layer of the polarizing plate. In addition, since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a transparent protective layer, a polarizing plate, etc. prevents the decrease in reflectance due to oxidation, and thus the long-term sustainability of the initial reflectance. In addition, it is preferable in view of avoiding the additional attachment of the protective layer.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell. When a liquid crystal display device is used in a relatively bright atmosphere, the incident light from the viewing side (display side) is reflected to display an image. In a relatively dark atmosphere, a liquid crystal display device or the like that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate is useful for forming a liquid crystal display device of a type that can save energy of using a light source such as a backlight in a bright atmosphere and can be used with a built-in light source even in a relatively dark atmosphere. It is.

  An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black-and-white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has an antireflection function.

  As a retardation plate, a birefringent film formed by uniaxially or biaxially stretching a polymer material, an alignment film obtained by aligning a liquid crystal monomer and then cross-linking and polymerizing, an alignment film of a liquid crystal polymer, an alignment of a liquid crystal polymer For example, the layer is supported by a separate film. The stretching treatment can be performed by, for example, a roll stretching method, a long gap stretching method, a tenter stretching method, a tubular stretching method, or the like. The stretching ratio is generally about 1.1 to 3 times in the case of uniaxial stretching, but is not limited thereto. The thickness of the retardation plate is not particularly limited, but is generally 10 to 200 μm, preferably 20 to 100 μm.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone. , Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyvinyl alcohol, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulosic polymers, or binary, ternary various copolymers, graft copolymers, Examples thereof include a mixture thereof. These polymer materials become oriented products (stretched films) by stretching or the like.

  As the liquid crystal monomer, either a lyotropic property or a thermotropic property can be used, but a thermotropic property is preferable from the viewpoint of workability. Examples thereof include those having a basic skeleton of a biphenyl derivative, a phenylbenzoate derivative, a stilbene derivative or the like into which a functional group such as an acryloyl group, a vinyl group or an epoxy group is introduced. Such a liquid crystal monomer is aligned using a known method such as a method using heat or light, a method of rubbing on the substrate, a method of adding an alignment aid, etc., and then this alignment is maintained. A method of fixing the orientation by crosslinking and polymerization with light, heat, electron beam or the like is preferably used.

  Examples of the liquid crystal polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. It is done. Specific examples of the main chain type liquid crystalline polymer include, for example, a nematic alignment polyester liquid crystalline polymer, a discotic polymer, and a cholesteric polymer having a structure in which a mesogen group is bonded to a spacer portion that imparts flexibility. . Specific examples of the side chain type liquid crystalline polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment imparting paraffin through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogen moiety composed of a substituted cyclic compound unit. These liquid crystal polymers are, for example, developed solutions of liquid crystalline polymers on alignment-treated surfaces such as those obtained by rubbing the surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or by obliquely depositing silicon oxide. Then, the heat treatment is performed.

  The retardation plate may have an appropriate retardation according to the purpose of use, such as those for the purpose of compensating for various wavelength plates or birefringence of the liquid crystal layer, viewing angle, and the like. What laminated | stacked the phase difference plate and controlled optical characteristics, such as phase difference, etc. may be used.

  The elliptically polarizing plate and the reflective elliptical polarizing plate are obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can also be formed by sequentially laminating them in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflective) polarizing plate and a retardation plate. An optical film such as a polarizing plate is excellent in quality stability, lamination workability, and the like, and has an advantage of improving the manufacturing efficiency of a liquid crystal display device and the like.

  The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. Examples of such a viewing angle compensation film include a retardation film, an alignment film such as a liquid crystal polymer, and a film in which an alignment layer such as a liquid crystal polymer is supported on a transparent substrate. A normal retardation plate uses a birefringent polymer film uniaxially stretched in the plane direction, whereas a retardation plate used as a viewing angle compensation film has a biaxially stretched biaxially stretched film. Refractive polymer film, biaxially stretched film such as birefringent polymer with a controlled refractive index in the thickness direction, stretched uniaxially in the plane direction and stretched in the thickness direction, etc. Is used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. Can be mentioned. The raw material polymer for the phase difference plate is the same as the polymer described in the previous phase difference plate, preventing coloration due to a change in the viewing angle based on the phase difference by the liquid crystal cell and expanding the viewing angle for good visual recognition. An appropriate one for the purpose can be used.

  In addition, an optical layer in which a liquid crystal polymer alignment layer, in particular an optically anisotropic layer composed of a discotic liquid crystal polymer gradient alignment layer, is supported by a triacetyl cellulose film because it has good visibility and achieves a wide viewing angle. A compensation retardation plate can be preferably used.

  Examples of the polarization conversion element include an anisotropic reflection polarization element and an anisotropic scattering polarization element. As an anisotropic reflection type polarizing element, a cholesteric liquid crystal layer, particularly an oriented film of a cholesteric liquid crystal polymer, or a circle of either a left-handed direction or a right-handed one, such as those in which the oriented liquid crystal layer is supported on a film substrate, is used. A composite of a material that reflects polarized light and transmits other light and a retardation plate having a phase difference of 0.25 times any wavelength in the reflection band, or a dielectric It is preferable to transmit linearly polarized light having a predetermined polarization axis and reflect other light, such as a multilayer thin film of a body or a multilayer laminate of thin film having different refractive index anisotropy. An example of the former can be a PCF series manufactured by Nitto Denko, and an example of the latter can be a DBEF series manufactured by 3M. A reflective grid polarizer can also be preferably used as the anisotropic reflective polarizing element. Examples thereof include Micro Wires manufactured by Maxtek. On the other hand, examples of the anisotropic scattering type polarizing element include DRPF manufactured by 3M.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. A polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to be incident to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light in a state other than the predetermined polarization state. . The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer provided on the rear side thereof and re-incident on the brightness enhancement film, and a part or all of the light is transmitted as light in a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the improvement film and supplying polarized light that is difficult to absorb to the polarizing film to increase the amount of light that can be used for liquid crystal image display and the like. That is, when light is incident through the polarizing film from the back side of the liquid crystal cell without using a brightness enhancement film, the light having a polarization direction that does not coincide with the polarizing axis of the polarizing film is almost polarized. It is absorbed by the film and does not pass through the polarizing film. That is, although it depends on the characteristics of the polarizing film used, approximately 50% of the light is absorbed by the polarizing film, and accordingly, the amount of light that can be used for liquid crystal image display or the like is reduced and the image becomes dark. The brightness enhancement film is reflected once by the brightness enhancement film without being incident on the polarization film with light having a polarization direction that is absorbed by the polarization film, and then inverted through a reflective layer provided on the rear side. The light is incident again on the brightness enhancement film, and only the polarized light in which the polarization direction of the light reflected and inverted between the two passes through the polarizer is transmitted to the polarizing film. Since it supplies, light, such as a backlight, can be efficiently used for the display of the image of a liquid crystal display device, and a screen can be made bright.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The light in the polarization state reflected by the brightness enhancement film is directed to the reflection layer and the like, and is uniformly diffused by passing through the installed diffusion plate. At the same time, the polarization state is canceled and the light becomes a non-polarization state. That is, the original natural light state is restored. The light in the non-polarized state, that is, the natural light state is directed to the reflection layer or the like, is reflected through the reflection layer or the like, and passes through the diffusion plate again and reenters the brightness enhancement film. By providing the diffusion plate that returns to the original natural light state, the brightness of the display screen can be maintained, and at the same time, the unevenness of the brightness of the display screen can be reduced and a uniform bright screen can be provided. By providing a diffuser plate that restores the original natural light state, the number of repetitions of the initial incident light is moderately increased, and it is possible to provide a uniform bright display screen combined with the diffuser function of the diffuser plate. It is done.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropy. Such as those having a cholesteric liquid crystal polymer alignment film or its alignment liquid crystal layer supported on a film substrate, reflecting either left-handed or right-handed circularly polarized light and transmitting other light Appropriate things such as can be used.

  Therefore, in the above type of brightness enhancement film that transmits linearly polarized light with the predetermined polarization axis, the transmitted light is directly incident on the polarization plate with the polarization axis aligned, thereby efficiently suppressing absorption loss due to the polarization plate. Can be transmitted. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be directly incident on the polarizing film, but from the point of suppressing absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable to make it enter into a polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region exhibits, for example, a retardation layer that functions as a quarter-wave plate for monochromatic light with a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method of superposing a retardation layer, for example, a retardation layer functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.

  In addition, the cholesteric liquid crystal layer can also be obtained by reflecting circularly polarized light in a wide wavelength range such as the visible light region by combining two or more layers with different reflection wavelengths and having an overlapping structure. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Moreover, the polarizing plate of this invention may consist of what laminated | stacked the polarizing plate and the optical layer of 2 layers or 3 layers or more like said polarization-separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-mentioned reflective polarizing plate or semi-transmissive polarizing plate and a retardation plate are combined may be used.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with the target phase difference characteristic.

  The polarizing film according to the present invention and the optical layer may be provided with an adhesive layer for bonding with other members such as a liquid crystal cell. The pressure-sensitive adhesive layer is not particularly limited, and can be formed of an appropriate pressure-sensitive adhesive such as acrylic, silicone, polyester, polyurethane, polyether, or rubber. This adhesive has the following features: prevention of foaming and peeling phenomenon due to moisture absorption, deterioration of optical properties due to thermal expansion differences, prevention of warping of liquid crystal cells, and formation of a high-quality and durable image display device. A pressure-sensitive adhesive layer having a low moisture absorption rate and excellent heat resistance is preferable. Furthermore, from the viewpoint of preventing changes in optical properties such as a polarizing film, those that do not require a high-temperature process during curing and drying are preferable, and those that do not require a long curing process or drying time are preferable. From such a viewpoint, an acrylic adhesive is preferably used in the present invention.

  Moreover, it can also be set as the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility. The adhesive layer may be provided on a necessary surface as necessary. For example, in a polarizing plate comprising a polarizing film and a transparent protective layer as in the present invention, an adhesive layer is provided on one or both sides of the protective layer as necessary. May be provided.

  Although the thickness of an adhesion layer is not specifically limited, 5-35 micrometers is preferable, More preferably, it is more preferable that it is 15-25 micrometers. By making the thickness of the adhesive layer in this range, the stress accompanying the dimensional behavior of the polarizing film and the polarizing plate can be relaxed.

  When the adhesive layer is exposed on the surface, it is preferable to temporarily cover the separator with a separator for the purpose of preventing contamination until the adhesive layer is put to practical use. The separator is formed on a suitable film in accordance with the above-mentioned transparent protective layer by a method of providing a release coat with an appropriate release agent such as a silicone-based, long-chain alkyl-based, fluorine-based or molybdenum sulfide as required. be able to.

  In addition, each layer such as the transparent protective layer, the optical layer, and the adhesive layer forming the polarizing plate and the optical film includes, for example, a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, and a nickel complex salt system. It may be provided with ultraviolet absorbing ability by an appropriate method such as a method of treating with an ultraviolet absorber such as a compound.

  The polarizing film according to the present invention is preferably used for forming an image display device such as a liquid crystal display device (LCD), an electroluminescence display device (ELD), a plasma display panel (PDP), and a field emission display (FED). it can.

  The polarizing film of the present invention can be preferably used for forming various devices such as a liquid crystal display device, for example, a reflective type or a transflective type in which a polarizing film or a polarizing plate is disposed on one side or both sides of a liquid crystal cell, Alternatively, it can be used in a liquid crystal display device such as a transmission / reflection type. The liquid crystal cell substrate may be either a plastic substrate or a glass substrate. The liquid crystal cell forming the liquid crystal display device is arbitrary. For example, an appropriate type such as an active matrix drive type represented by a thin film transistor type, a simple matrix drive type represented by a twist nematic type or a super twist nematic type, etc. A liquid crystal cell may be used.

  Moreover, when providing a polarizing plate and another optical film in the both sides of a liquid crystal cell, they may be the same and may differ. Furthermore, when forming the liquid crystal display device, for example, appropriate components such as a prism array sheet, a lens array sheet, a light diffusion plate, and a backlight can be arranged in one or more layers at appropriate positions.

  Next, an organic electroluminescence display device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, It is also known to have various combinations such as a laminate of such a light emitting layer and an electron injection layer composed of a perylene derivative, etc., or a laminate of these hole injection layer, light emitting layer, and electron injection layer. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the fluorescent material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be expected from this, the current and the emission intensity show strong nonlinearity due to rectification with respect to the applied voltage.

  In the organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and usually a transparent electrode formed of a transparent conductor such as indium tin oxide (ITO) is used. Used as the anode. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation film can be provided between the transparent electrode and the polarizing plate.

  Since the retardation film and the polarizing film have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization function. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation film with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation film to π / 4. .

  That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light is generally elliptically polarized light by the retardation film, but becomes circularly polarized light especially when the retardation film is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the retardation film is π / 4. .

  This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again by the retardation film. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  The PDP generates a discharge in a rare gas enclosed in the panel, particularly a gas mainly composed of neon, and R, G, and B phosphors applied to the cell of the panel by vacuum ultraviolet rays generated at that time. By generating the image, it is possible to display an image.

  In the image display device market as described above, in-house manufacturing is required to consistently carry out the processing steps from punching of the optical film raw material to selection and bonding in order to reduce the price. In the present invention, when the cut polarizing plate is used for a display as it is, the size of the chip-cut polarizing film is arbitrary, but generally the one having a length of 10 cm to 130 cm and a width of 10 cm to 130 cm is used. It is done. Although there is no upper limit in particular in the magnitude | size of a display, it depends on the base material width | variety for polarizing films, such as a transparent protective film which can be made now, and a PVA film. In the in-house manufacturing method that performs integrated production from optical film post-processing (cutting) to bonding to a cell, it is necessary to immediately measure the defective area. Therefore, in the past, an inspection process was required after chip cutting, and defective products were excluded in the inspection process, but the polarizing film obtained by the present invention has excellent in-plane uniformity, so the inspection process and its purpose after chip cutting The process of attaching to an image display element such as a liquid crystal display element or an EL display element can be performed in one line without going through a transport process, a packing process, and an unpacking process.

  The present invention will be described more specifically with reference to the following examples and comparative examples. However, the present invention is not limited to these examples and comparative examples.

Example 1
Using a polyvinyl alcohol (PVA) film having a thickness of 75 μm and a width of 100 mm (manufactured by Kuraray Co., Ltd., degree of polymerization 2400), it undergoes swelling, dyeing, crosslinking, stretching, washing with water and drying treatment steps, and then a polarizing film (thickness) About 28 μm). However, when producing a polarizing film, as shown in FIG. 3, a roll whose surface is mainly composed of vinyl chloride and NBR is used as a film transporting holder during swelling, dyeing, crosslinking, stretching, and washing bath. Two films were processed in two rows. Furthermore, after saponifying a triacetyl cellulose film (thickness of 80 μm) by immersing it in an alkaline aqueous solution for 60 seconds on both sides of this polarizing film with a PVA-based adhesive, it is at 60 ° C. for 4 minutes. It dried and it was set as the polarizing plate. In addition, in each said process process, as shown in FIG. 1, the film was conveyed using a roll, and in the process process accompanied by extending | stretching, it extended | stretched by setting the peripheral speed difference to the pinch roll before and behind a process process. . Each processing condition of a polarizing film manufacturing process is as follows.
(Swelling treatment process) Stretching 3.0 times in pure water at 30 ° C.
(Dyeing treatment step) Immerse in a 0.5 wt% iodine aqueous solution (I / KI (weight ratio) = 1/10) at 30 ° C. for 60 seconds.
(Crosslinking treatment step) Immersion in 3 wt% boric acid and 2 wt% KI aqueous solution at 30 ° C for 60 seconds.
(Stretching treatment step) Stretching to a total draw ratio of 5.5 times in a 4 wt% boric acid and 3 wt% KI aqueous solution at 60 ° C.
(Washing treatment step) After dipping in a 5 wt% KI aqueous solution at 30 ° C for 20 seconds, the water is removed using an air knife.
(Drying process step) Drying at 50 ° C for 1 minute while maintaining the tension.
The obtained polarizing plate was measured for single transmittance and degree of polarization. The results are shown in Table 1.

Example 2
A polarizing film and a polarizing plate were obtained in the same manner as in Example 1 except that three films were processed using rolls arranged in three rows horizontally as shown in FIG. The measurement results of the obtained polarizing plate are shown in Table 1.

Example 3
A polarizing film and a polarizing plate were obtained in the same manner as in Example 1 except that the two films were processed in a form in which the rolls were arranged vertically in two stages as shown in FIG. It was. The measurement results of the obtained polarizing plate are shown in Table 1.

Reference Example Using a PVA film having a width of 100 mm, as shown in FIG. 2, a polarizing film and a polarizing film were prepared in the same manner as in Example 1 except that one film was transported for one roll. A polarizing plate was obtained. The measurement results of the obtained polarizing plate are shown in Table 1.

Comparative Example 1
Polarization is performed in the same manner as in Example 1 except that a PVA film having a width of 200 mm is used to form one film per roll (conventional method) as shown in FIG. A film and a polarizing plate were obtained. The measurement results of the obtained polarizing plate are shown in Table 1.

Comparative Example 2
Polarization is performed in the same manner as in Example 1 except that a PVA film having a width of 300 mm is used to form one film per roll (conventional method) as shown in FIG. A film and a polarizing plate were obtained. The measurement results of the obtained polarizing plate are shown in Table 1.

(Optical characteristics measurement method)
The polarizing plates produced in Examples, Reference Examples or Comparative Examples were cut into a size of 35 mm × 25 mm so as to be 45 ° with respect to the stretching direction, and a spectrophotometer (Murakami Color Research Laboratory: DOT-3) was cut. ) Were used to measure single transmittance, parallel transmittance (H ₀ ), and orthogonal transmittance (H ₉₀ ), and the degree of polarization was determined from the values according to the following formula. Note that these transmittances are Y values obtained by correcting the visibility with a J1SZ 8701 2 degree visual field (C light source).
Polarization degree (%) = {(H ₀ −H ₉₀ ) / (H ₀ + H ₉₀ )} ^1/2 × 100

上記表１の結果から、優れた光学特性（偏光度）の偏光フィルムが生産量を落とすことなく得られることが明らかである。

From the results in Table 1 above, it is clear that a polarizing film having excellent optical properties (polarization degree) can be obtained without reducing the production amount.

It is an example of the polarizing film manufacturing process process by this invention. It is an example of the conventional polarizing film manufacturing process. It is processing bath sectional drawing when it sees from the conveyance direction front in the case of arrange | positioning two conveyance films side by side using two holders for film conveyance. It is processing bath sectional drawing when it sees from the conveyance direction front at the time of arrange | positioning two films of conveyance films horizontally using one holder for film conveyance. It is processing bath sectional drawing when it sees from the conveyance direction front in the case of carrying | stacking a conveyance film vertically 3 steps | paragraphs. It is processing bath sectional drawing when it sees from the conveyance direction front at the time of arranging a conveyance film 2 steps | paragraphs 2 rows vertically and horizontally. It is processing bath sectional drawing when it sees from the conveyance direction front surface at the time of arranging a conveyance film 3 rows horizontally.

Explanation of symbols

1 treatment bath 11 swelling treatment process (bath)
12 Dyeing process (bath)
13 Crosslinking process (bath)
14 Stretching process (bath)
15 Washing process (bath)
16 Drying process (bath)
2 Film transport holder (roll)
3 Treatment liquid 4 Original film 5 Conveying film 6 Polarizing film

Claims (7)

In the method for producing a polarizing film having a dyeing treatment step and a stretching treatment step, a plurality of films are immersed in at least one treatment bath at the same time without being contacted , and the plurality of films are arranged vertically. A method for producing a polarizing film, wherein the polarizing film is immersed in a form . 2. The method for producing a polarizing film according to claim 1, wherein 2 to 4 films are simultaneously immersed in the same treatment bath without contacting them. 3. The method for producing a polarizing film according to claim 1, wherein the PVA film is dyed with a dichroic substance in the dyeing treatment step, and then uniaxially drawn in the drawing treatment step. The method for producing a polarizing film according to claim 1 , wherein the processing step of the plurality of films branches into a plurality of steps in the middle. At the same time a plurality of films, have a treatment bath having a film transport holders for immersion in the same treatment bath without contacting, further, is immersed in a side-by-side form the plurality of films in the vertical An apparatus for producing a polarizing film, comprising a film transport holder for the purpose . The polarizing film manufacturing apparatus of Claim 5 which has a processing bath provided with the holder for film conveyance for processing 2-4 films simultaneously. 6. The polarizing film manufacturing apparatus according to claim 5 , further comprising a film transporting holder that branches the processing steps of the plurality of films into a plurality of steps in the middle.

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