JP2008040251A - Manufacturing method of polarizer, polarizer, polarizing plate, optical film, and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a polarizer having high transmittance and high polarization degree. <P>SOLUTION: A polyvinyl alcohol film is subjected to a dyeing process, a cross-linking process and a stretching process to manufacture the polarizer. In this manufacturing method of the polarizer, the dyeing process is carried out by immersing the polyvinyl alcohol film in a mixed processing liquid containing an iodide compound and ozone. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a polarizer and a polarizer obtained by the production method. The present invention also relates to a polarizing plate and an optical film using the polarizer, and further to an image display device such as a liquid crystal display device, an organic EL display device and a PDP using the polarizing plate and the optical film.

  Liquid crystal display devices are used in personal computers, TVs, monitors, mobile phones, PDAs and the like. Conventionally, as a polarizer used for a liquid crystal display device or the like, a dyed polyvinyl alcohol film has been used because it has both high transmittance and high degree of polarization. The said polarizer is manufactured by drying, after giving each process of swelling, dyeing | staining, bridge | crosslinking, extending | stretching etc. to a polyvinyl alcohol-type film in a bath, for example. Moreover, the said polarizer is normally used as a polarizing plate by which protective films, such as a triacetyl cellulose, were bonded on the single side | surface or both surfaces using the adhesive agent.

  In recent years, liquid crystal display devices have been improved in performance, and liquid crystal panels have been required to improve contrast in order to obtain high visibility. That is, it is desired that black is black and white is whiter and brighter, and accordingly, further improvement in the polarization performance of the polarizer is required. Therefore, it is very important for the polarization performance to have a high transmittance while having a high degree of polarization.

In order to obtain such a polarizing plate, many methods have been proposed so far. For example, a polarizer obtained by uniaxially stretching a film using polyvinyl alcohol having a high degree of polymerization has been proposed (see Patent Document 1 and Patent Document 2). According to these methods, a polarizer having a high transmittance and a high degree of polarization can be obtained, and further improvement in performance is desired for the polarizer.
Japanese Patent No. 2543748 Japanese Patent No. 2631403

  An object of the present invention is to provide a method for producing a polarizer having high transmittance and high degree of polarization.

  Moreover, this invention aims at providing the polarizer obtained by the said manufacturing method, the polarizing plate using the said polarizer, and an optical film. Furthermore, an object of this invention is to provide the image display apparatus using the said polarizing plate and an optical film.

  As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by a method for producing a polarizer shown below, and have completed the present invention.

That is, the present invention provides a method for producing a polarizer in which a polyvinyl alcohol film is subjected to at least a dyeing process, a crosslinking process and a stretching process.
A dyeing process is related with the manufacturing method (1) of a polarizer characterized by performing by immersing a polyvinyl alcohol system film in mixed processing liquid containing an iodide compound and ozone.

  In the manufacturing method (1) of the said polarizer, a crosslinking process can be simultaneously performed with a dyeing process by making a mixed processing liquid containing an iodide compound and ozone contain a crosslinking agent. Moreover, in the manufacturing method (1) of the said polarizer, an extending | stretching process can be simultaneously performed with a dyeing process. Moreover, a bridge | crosslinking process and an extending | stretching process can be performed simultaneously with a dyeing process.

Further, the present invention provides a method for producing a polarizer in which a polyvinyl alcohol film is subjected to at least a dyeing process, a crosslinking process and a stretching process.
The dyeing process includes an iodide compound treatment process in which a polyvinyl alcohol film is immersed in a treatment liquid containing an iodide compound,
It is related with the manufacturing method (2) of the polarizer characterized by performing by the ozone treatment process which immerses a polyvinyl-alcohol-type film in the process liquid containing ozone.

  In the manufacturing method (2) of the said polarizer, it is preferable to perform an ozone treatment process after performing an iodide compound treatment process. In this case, the treatment liquid containing the iodide compound preferably contains a crosslinking agent.

  In the said manufacturing method (2) of a polarizer, a crosslinking process can be given with a dyeing process by making the process liquid containing ozone contain a crosslinking agent. Moreover, in the manufacturing method (2) of the said polarizer, an extending process can be simultaneously performed with a dyeing process by giving an extending process with a dyeing process. Moreover, a bridge | crosslinking process and an extending | stretching process can be performed simultaneously with a dyeing process.

  In the manufacturing method (1) or (2) of the polarizer, potassium iodide is preferable as the iodide compound.

  In the manufacturing method (1) or (2) of the polarizer, a swelling step can be provided before the dyeing step.

  Moreover, in the said manufacturing method (1) or (2) of a polarizer, after performing the dyeing | staining process, a bridge | crosslinking process, and an extending process, a washing | cleaning process can be provided.

  Moreover, this invention relates to the polarizer obtained by the said manufacturing method (1) or (2).

  The present invention also relates to a polarizing plate in which a transparent protective layer is provided on at least one surface of the polarizer.

  The present invention also relates to an optical film in which at least one of the polarizer or the polarizing plate is laminated.

  The present invention also relates to an image display device using at least one of the polarizer, the polarizing plate or the optical film.

  Conventionally, a polarizer is manufactured by subjecting a polyvinyl alcohol film to at least a dyeing process, a crosslinking process, and a stretching process. The dyeing step has been performed by immersing a polyvinyl alcohol film in a solution containing iodine or a dichroic dye. On the other hand, in the manufacturing method (1) of this invention, a dyeing | staining process is performed by immersing a polyvinyl alcohol-type film in the mixed process liquid containing an iodide compound and ozone. In addition, in the production method (2) of the present invention, an iodide compound treatment step of immersing a polyvinyl alcohol film in a treatment liquid containing an iodide compound, and a polyvinyl alcohol film in a treatment liquid containing ozone. The dyeing process is performed by the ozone treatment process in which the material is immersed. The order of the iodide compound treatment step and the ozone treatment step in the production method (2) is not particularly limited, but it is preferable that the ozone treatment step is performed after the iodide compound treatment step is performed on the polyvinyl alcohol film. In the present invention, a polarizer having a high transmittance and a high degree of polarization is obtained by performing such a dyeing step.

In the present invention, it is unclear how the optical characteristics are improved, but the following matters are estimated. That is, ozone reacts with an iodide compound such as potassium iodide to produce iodine (2KI + O ₃ + H ₂ O → I ₂ + O ₂ +2 KOH). As described above, in the dyeing process of the present invention, the dyeing process is performed by iodine generated by the reaction between ozone and the iodide compound. That is, the polyvinyl alcohol film is immersed in a mixed treatment liquid containing an iodide compound and ozone in the production method (1), and in a treatment liquid containing an iodide compound and ozone in the production method (2). As a result, the film is impregnated with ozone, and the impregnated ozone is involved in the iodine formation reaction, and due to the action of the iodine produced there, the absorption wavelength region is wide and absorption with less dispersion due to wavelength It is considered that a polarizer having characteristics is obtained.

  Moreover, in the said manufacturing method (1), in order to produce | generate iodine in the mixed process liquid containing an iodide compound and ozone, the iodine supply amount from the outside can be reduced by using the said process liquid, Furthermore, It is also possible to dispense with iodine supply. Moreover, also in a manufacturing method (2), the polyvinyl-alcohol-type film is immersed in the iodide compound process which immerses a polyvinyl-alcohol-type film in the process liquid containing an iodide compound, and the process liquid containing ozone. By passing through the ozone treatment step, iodine is generated, the amount of iodine supplied from the outside can be reduced, and furthermore, the supply of iodine can be made completely unnecessary. Thus, in the dyeing process of the present invention, the expensive iodine supply amount is reduced or unnecessary, which is very advantageous in terms of cost.

  Moreover, in this invention, since the said process liquid can serve as a swelling process, it is not necessary to provide a swelling process in particular. Further, the treatment liquid (the mixed treatment liquid containing the iodide compound and ozone of the production method (1) or the treatment liquid containing the iodide compound of the production method (2) and / or ozone is produced, which generates iodine. In the treatment liquid), the crosslinking step can be effectively performed together with the dyeing step by containing a crosslinking agent. In particular, in the production method (2), when the ozone treatment step is performed after the iodide compound treatment step, a crosslinking agent is included in the treatment liquid containing the iodide compound used in the iodide compound treatment step. Is preferred. By adding a crosslinking agent to the treatment liquid containing the iodide compound, the polyvinyl alcohol film is hydrophobized, and the iodide compound impregnated in the polyvinyl alcohol film in the iodide compound treatment step flows out in the ozone treatment step. This makes it possible to hold the iodide compound necessary for sufficient dyeing in the polyvinyl alcohol film. Furthermore, a crosslinking process can be effectively performed with a dyeing process by performing an extending | stretching process with the said dyeing process. Furthermore, the dyeing process, the crosslinking process, and the stretching process can be effectively performed. Thus, in the present invention, by adopting the dyeing step, it becomes possible to simultaneously perform a plurality of conventional steps, and the manufacturing process can be simplified.

  Hereinafter, the present invention will be described with reference to the drawings. In the present invention, the polyvinyl alcohol film is subjected to a dyeing process, a crosslinking process, and a stretching process. FIG. 1 shows an example of a conventional method for producing a polarizer. In FIG. 1, the case where the dyeing | staining process (B), the bridge | crosslinking process (C), and the extending process (D) are performed to the polyvinyl alcohol-type film P in this order is illustrated. Moreover, in FIG. 1, the case where the swelling process (A) is provided before the dyeing process (B) and the washing process (E) is provided after the stretching process (D) is illustrated. In FIG. 1, each step is represented as a treatment bath (a2, b2, c2, d2, e2) containing a treatment liquid (a1, b1, c1, d1, e1). 2 to 5, each process other than the dyeing process (B) can be provided with a treatment bath containing the same treatment liquid.

  FIG. 2 shows a case where a dyeing step (B-1) is provided instead of the dyeing step (B) in FIG. In the dyeing step (B-1), a mixed treatment liquid (b1-1) containing an iodide compound and ozone is used. In the dyeing step (B-1), iodine staining of the polyvinyl alcohol film P is performed with iodine generated by the reaction between the iodide compound and ozone. Although the case where the swelling process (A) is provided is illustrated in FIG. 2, since the dyeing process (B-1) can also serve as the swelling process (A), the swelling process (A) is not particularly provided. Also good.

  In FIG. 3, it is a case where a dyeing process (B-1) and a bridge | crosslinking process (C) are performed simultaneously. In this case, the mixed treatment liquid (b1-1) contains a crosslinking agent (for example, boric acid) in addition to the iodide compound and ozone. FIG. 4 shows a case where the dyeing step (B-1), the crosslinking step (C) and the stretching step (D) are performed simultaneously. Also in this case, the mixed treatment liquid (b1-1) contains a crosslinking agent (for example, boric acid) in addition to the iodide compound and ozone.

  FIG. 5 shows a case where an iodide compound treatment step (B-11) and an ozone treatment step (B-12) are provided in place of the dyeing step (B) in FIG. In the iodide compound treatment step (B-11), a treatment liquid (b-11) containing an iodide compound is used. In the ozone treatment step (B-12), a treatment liquid (b-12) containing ozone is used. In the iodide compound treatment step (B-11), the polyvinyl alcohol film P is impregnated with the iodide compound, and in the ozone treatment step (B-12), the polyvinyl alcohol is produced by the iodine generated by the reaction between the iodide compound and ozone. The system film P is subjected to iodine staining. Therefore, in FIG. 5, the iodide compound treatment step (B-11) can be said to be a preliminary step of the ozone treatment step (B-12) in which iodine staining is actually performed. In addition, in FIG. 5, although the case where an ozone treatment process (B-12) is given after performing the iodide compound treatment process (B-11) to the polyvinyl alcohol-type film P is illustrated, an ozone treatment process ( After performing B-12), the iodide compound treatment step (B-11) can be performed. Although not shown in FIG. 5, in the ozone treatment step (B-12) in which iodine staining is performed, the crosslinking step (C) and the stretching step (D) are simultaneously performed as shown in FIGS. You can also. In addition, like FIG. 2, FIG. 5 illustrates the case where the swelling step (A) is provided, but the iodide compound treatment step (B-11) can also serve as the swelling step (A). Therefore, the swelling step (A) does not need to be particularly provided.

  2 to 4 illustrate the step (B-1) as the staining step, and FIG. 5 illustrates the iodide compound treatment step (B-11) and the ozone treatment step (B-12). They can be provided in combination. 2, 3, and 5, steps (B-1) to (D) are performed in this order. However, these steps can be performed simultaneously with the dyeing step as described above, and provided separately. The crosslinking step (C) and the stretching step (D) can also be performed simultaneously. In addition, the order of these steps can be changed. They can also be applied multiple times. In FIG. 2, FIG. 3, FIG. 5, the process (C) and the process (D) are provided with a treatment bath, but if the ozone treatment process (F) is provided, the process (C) and the process ( For D), means other than the treatment bath may be employed.

  As the polyvinyl alcohol film applied to the polarizer of the present invention, a film having translucency in the visible light region and capable of dispersing and adsorbing iodine can be used without particular limitation. Usually, a polyvinyl alcohol film having a thickness of about 30 to 150 μm is used.

  As a polyvinyl alcohol-type film, the polyvinyl alcohol-type film conventionally used for the polarizer is used suitably, for example. Examples of the material for the polyvinyl alcohol film include polyvinyl alcohol and derivatives thereof. Derivatives of polyvinyl alcohol include polyvinyl formal, polyvinyl acetal and the like, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, alkyl esters thereof, acrylamide and the like. can give. Polyvinyl alcohol having a polymerization degree of about 1000 to 10000 and a saponification degree of about 80 to 100 mol% is generally used.

  In addition to the above, polyvinyl alcohol films include hydrophilic polymer films such as partially saponified ethylene / vinyl acetate copolymers, polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. Etc.

  The polyvinyl alcohol film may contain additives such as a plasticizer and a surfactant. Examples of the plasticizer include polyols and condensates thereof, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The amount of the plasticizer used is not particularly limited, but is preferably 20% by weight or less in the polyvinyl alcohol film.

  In the manufacturing method (1) of the polarizer of this invention, a process (B-1) is given to a polyvinyl alcohol-type film as a dyeing process. On the other hand, in the method (2) for producing a polarizer of the present invention, an iodide compound treatment step (B-11) and an ozone treatment step (B-12) are performed as the dyeing step. Further, in the production method (1) or (2), the crosslinking step (C) and the stretching step (D) are performed.

  In the dyeing step (B-1) in the production method (1), the polyvinyl alcohol film is immersed in a mixed treatment liquid (b1-1) containing an iodide compound and ozone, and is generated from the iodide compound and ozone. This is done by adsorbing and orienting iodine.

  Examples of the iodide compound include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. And the like are used. As the iodide compound, potassium iodide is preferred. The iodide compound used in the present invention is the same as described above when used in other steps.

  The concentration of the iodide compound in the mixed treatment liquid (b1-1) is adjusted so as to ensure the amount consumed for the reaction with ozone and the function of the produced iodine as an auxiliary agent. The concentration of the iodide compound is about 0.1 to 50% by weight, preferably about 0.5 to 10% by weight. When the concentration of the iodide compound is low, the amount of iodine produced is also reduced, the polyvinyl alcohol film is not sufficiently dyed, and it tends to be difficult to obtain a polarizer with a high degree of polarization. On the other hand, when the concentration of the iodide compound is high, the dyeing becomes excessive, and it becomes difficult to obtain a polarizer having a high transmittance.

  The concentration of ozone in the mixed treatment liquid (b1-1) is preferably about 0.1 to 100 ppm. More preferably, it is 1-20 ppm, Most preferably, it is 1-10 ppm. When the ozone concentration is low, it is necessary to increase the immersion time in order to sufficiently dye the polyvinyl alcohol film. On the other hand, when the ozone concentration is high, the polyvinyl alcohol film tends to be decomposed.

  The treatment temperature of the mixed treatment liquid (b1-1) is usually in the range of about 5 to 70 ° C, preferably 10 to 50 ° C, and further 20 to 40 ° C. The treatment time varies depending on the ozone concentration, but is usually about 10 to 240 seconds, preferably 20 to 120 seconds. When the treatment time is short, the polyvinyl alcohol film cannot be sufficiently impregnated with ozone. On the other hand, when the treatment time is long, the polyvinyl alcohol film tends to be decomposed.

  In the dyeing step in the production method (2), the iodide compound treatment step (B-) in which the polyvinyl alcohol film is immersed in the treatment liquid (b1-11) containing the iodide compound in the polyvinyl alcohol film. 11) and the ozone treatment step (B-12) in which the polyvinyl alcohol film is immersed in the treatment liquid (b1-12) containing ozone, the produced iodine is adsorbed and oriented on the polyvinyl alcohol film. By doing. The order in which the iodide compound treatment step (B-11) and the ozone treatment step (B-12) are performed is not particularly limited, but the iodide compound treatment step (B-11) is performed, and then the ozone treatment step (B- It is preferable to apply 12).

  The concentration of the iodide compound in the treatment liquid (b1-11) containing the iodide compound is adjusted so that the amount consumed for the reaction with ozone and the function of the produced iodine as an auxiliary agent can be secured. The concentration of the iodide compound is about 0.1 to 50% by weight, preferably about 0.5 to 10% by weight. When the concentration of the iodide compound is low, the amount of iodine produced is also reduced, the polyvinyl alcohol film is not sufficiently dyed, and it tends to be difficult to obtain a polarizer with a high degree of polarization. On the other hand, when the concentration of the iodide compound is high, the dyeing becomes excessive, and it becomes difficult to obtain a polarizer having a high transmittance.

  The treatment temperature of the treatment liquid (b1-11) containing an iodide compound is usually about 5 to 70 ° C, preferably 10 to 50 ° C, and further 20 to 40 ° C. The treatment time is usually about 10 to 240 seconds, preferably 20 to 120 seconds. If the treatment time is short, iodine is not sufficiently generated, whereas if the treatment time is long, the adsorption of iodine is excessive.

  The concentration of ozone in the treatment liquid (b1-12) containing ozone is preferably about 0.1 to 100 ppm. More preferably, it is 1-20 ppm, Most preferably, it is 1-10 ppm. When the ozone concentration is low, it is necessary to increase the immersion time in order to sufficiently dye the polyvinyl alcohol film. On the other hand, when the ozone concentration is high, the polyvinyl alcohol film tends to be decomposed.

  The treatment temperature of the treatment liquid (b1-12) containing ozone is usually about 5 to 70 ° C, preferably 10 to 50 ° C, and more preferably 20 to 40 ° C. The treatment time varies depending on the ozone concentration, but is usually about 10 to 240 seconds, preferably 20 to 120 seconds. When the treatment time is short, the polyvinyl alcohol film cannot be sufficiently impregnated with ozone. On the other hand, when the treatment time is long, the polyvinyl alcohol film tends to be decomposed.

  In the preparation of the mixed treatment liquid (b1-1) containing the iodide compound and ozone used in the production method (1) and the treatment liquid (b1-12) containing ozone used in the production method (2), It can be prepared by the method. For example, ozone generated by the discharge method, electrolysis method, ultraviolet lamp method, etc. can be converted into ozone by dissolving the generated ozone in water by the bubble dissolution method, ejector dissolution method, diaphragm dissolution method, and packed bed dissolution method. An aqueous solution can be prepared.

  In the manufacturing method (1) of the polarizer of this invention, a swelling process (A) can be given before giving a dyeing process (B-1). Moreover, in the manufacturing method (2) of the polarizer of this invention, a swelling process (A) can be performed before performing an iodide compound process process (B-11) or an ozone treatment process (B-12). In addition to washing the surface of the polyvinyl alcohol film and the antiblocking agent by the swelling step (A), there is also an effect of preventing unevenness such as uneven dyeing by swelling the polyvinyl alcohol film.

  In the swelling step (A), water, distilled water, or pure water is usually used as the treatment liquid (treatment liquid a1 in FIGS. 2 and 5). If the main component is water, the treatment solution may contain a small amount of an iodide compound, an additive such as a surfactant, alcohol, or the like. Further, when an iodide compound is contained in the treatment liquid, the iodide compound concentration is preferably about 0.1 to 10% by weight, more preferably 0.2 to 5% by weight.

  The treatment temperature in the swelling step (A) is usually preferably adjusted to about 20 to 45 ° C. Furthermore, it is preferable that it is 25-40 degreeC. In addition, when there is swelling unevenness, the portion is the dyeing step (B-1) in the production method (1) or the iodide compound treatment step (B-11) or the ozone treatment step (B-12) in the production method (2). In this case, swelling unevenness is prevented from occurring because of uneven coloring. The immersion time is usually about 10 to 300 seconds, preferably 20 to 240 seconds.

  In the swelling step (A), it can be appropriately stretched. The draw ratio is usually 6.5 times or less with respect to the original length of the polyvinyl alcohol film. Preferably, from the viewpoint of optical properties, the draw ratio is preferably 1.2 to 6.5 times, more preferably 2 to 4 times, and even more preferably 2 to 3 times. In the swelling step (A), by stretching, the stretching in the stretching step (D) applied after the swelling step (A) can be controlled to be small, and the film can be controlled so as not to be stretched and broken. On the other hand, when the stretching ratio in the swelling process (A) is increased, the stretching ratio in the stretching process (D) is decreased, and in particular, when the stretching process (D) is performed after the crosslinking process (C), the optical characteristics. This is not preferable.

  In the present invention, the dyeing step (B-1) in the production method (1) or the iodide compound treatment step (B-11) or the ozone treatment step (B-12) in the production method (2) is performed in the swelling step ( A) can also be used. When the dyeing step (B-1), the iodide compound treatment step (B-11) or the ozone treatment step (B-12) also serves as the swelling step (A), the dyeing step (B-1) or iodination Stretching is preferably performed in the compound treatment step (B-11) or the ozone treatment step (B-12). In this case, as shown in FIGS. 2, 3, and 5, the stretching step (D) is provided separately. On the other hand, as shown in FIG. 4, the stretching step (D) can be performed together with the dyeing step (B-1), the iodide compound treatment step (B-11) or the ozone treatment step (B-12).

  The crosslinking step (C) is usually performed with a boron compound as a crosslinking agent. The order of the crosslinking step (C) is not particularly limited. The crosslinking step (C) can be performed together with the stretching step (D). The crosslinking step (C) may be performed together with the dyeing step (B-1) in the production method (1) or the iodide compound treatment step (B-11) or the ozone treatment step (B-12) in the production method (2). And can be cross-linked with the dyeing process. In particular, in the production method (2), when the ozone treatment step (B-12) is performed after the iodide compound treatment step (B-11), the iodine compound treatment step (B-11) The treatment liquid (b1-11) containing a chemical compound preferably contains a crosslinking agent. The crosslinking step (C) can be performed a plurality of times. Examples of the boron compound include boric acid and borax. The boron compound is generally used in the form of an aqueous solution or a water-organic solvent mixed solution (treatment liquid c1 in FIGS. 2 and 5). Usually, an aqueous boric acid solution is used. The boric acid concentration of the boric acid aqueous solution is about 0.1 to 13% by weight, preferably 2 to 13% by weight. In order to impart heat resistance depending on the degree of crosslinking, the boric acid concentration is preferably used. The boric acid aqueous solution or the like can contain an iodide compound such as potassium iodide. The iodide solution can be contained in the boric acid aqueous solution. The iodide compound concentration is preferably about 0.1 to 10% by weight, more preferably 0.2 to 5% by weight.

  The crosslinking step (C) can be performed by immersing the polyvinyl alcohol film in an aqueous boric acid solution or the like. In addition, a boron compound or the like can be applied to the polyvinyl alcohol film by a coating method, a spraying method, or the like. The processing temperature in a bridge | crosslinking process (C) is 25 degreeC or more normally, Preferably it is 30-85 degreeC, Furthermore, it is the range of 30-60 degreeC. The treatment time is usually about 10 to 800 seconds, preferably about 30 to 500 seconds.

  The stretching step (D) is usually performed by performing uniaxial stretching. This stretching method can be performed together with the dyeing step (B-1) in the production method (1) or the iodide compound treatment step (B-11) or the ozone treatment step (B-12) in the production method (2). It can be applied together with the crosslinking step (C). As the stretching method, either a wet stretching method or a dry stretching method can be adopted, but it is preferable to use a wet stretching method. As the wet stretching method, for example, after the dyeing step (B-1) is performed in the production method (1), the iodide compound treatment step (B-11) or the ozone treatment step (B-) is performed in the production method (2). After applying 12), it is general to perform stretching. Moreover, it can extend | stretch with a bridge | crosslinking process (C). On the other hand, in the case of dry stretching, examples of the stretching means include an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. In the stretching means, the unstretched film is usually heated. The stretching step (D) can be performed in multiple stages. 2, 3, and 5 exemplify a wet stretching method in which stretching is performed in the treatment liquid d <b> 1.

  The treatment liquid used in the wet stretching method can contain an iodide compound. The iodide compound concentration is preferably about 0.1 to 10% by weight, more preferably 0.2 to 5% by weight. The treatment temperature in the stretching step (D: wet stretching method) is usually 25 ° C. or higher, preferably 30 to 85 ° C., more preferably 30 to 60 ° C. The immersion time is usually about 10 to 800 seconds, preferably about 30 to 500 seconds.

  In the stretching step (D), the total stretching ratio is set such that the total stretching ratio is in the range of 3 to 17 times the original length of the polyvinyl alcohol film. Preferably it is 4-10 times, More preferably, it is 4-8 times. That is, the total draw ratio refers to a cumulative draw ratio including stretching in those steps when stretching is involved in the swelling step (A) other than the stretching step (D). The total draw ratio is appropriately determined in consideration of the draw ratio in the swelling step (A) and the like. When the total draw ratio is low, the orientation is insufficient and it is difficult to obtain a polarizer having high optical properties (polarization degree). On the other hand, if the total draw ratio is too high, stretch breakage is likely to occur, and the polarizer becomes too thin, which may reduce the workability in the subsequent process.

  In the manufacturing method of the polarizer of this invention, before performing a drying process finally, a washing | cleaning process (E) can be given other than the said process. By the washing step (E), precipitates generated on the surface of the polyvinyl alcohol film (stretched film) can be removed.

  In the cleaning step (E), for example, water, distilled water, pure water or the like is used as the processing liquid (the processing liquid e1 in FIGS. 2 and 3). Moreover, the said process liquid can use the aqueous solution containing iodide compounds, such as potassium iodide. For example, the aqueous solution preferably has a potassium iodide concentration of about 0.5 to 10% by weight, more preferably 1 to 8% by weight.

  The washing step (E) is usually performed by immersing a polyvinyl alcohol film in the treatment liquid. The temperature of the treatment liquid in the washing step (E) is usually in the range of 5 to 50 ° C, preferably 10 to 45 ° C, more preferably 15 to 40 ° C. The immersion time is usually about 1 to 300 seconds, preferably about 10 to 240 seconds. The cleaning with the aqueous solution can be performed in combination with water cleaning, and can be performed before or after the water cleaning.

  In addition to the steps (A) to (E), metal ion treatment can be performed (not shown). The metal ion treatment is performed by immersing a polyvinyl alcohol film in an aqueous solution containing a metal salt. Various metal ions are contained in the polyvinyl alcohol film by metal ion treatment.

  As metal ions, metal ions of transition metals such as cobalt, nickel, zinc, chromium, aluminum, copper, manganese, and iron are particularly preferably used in terms of color tone adjustment and durability. Among these metal ions, zinc ions are preferable from the viewpoints of color tone adjustment and heat resistance. Examples of the zinc salt include zinc halides such as zinc chloride and zinc iodide, zinc sulfate, and zinc acetate.

  A metal salt solution is used for the metal ion treatment. Hereinafter, zinc impregnation treatment will be described as a representative example of the case of using a zinc salt aqueous solution among metal ion treatments.

  The concentration of zinc ions in the zinc salt aqueous solution is about 0.1 to 10% by weight, preferably 0.3 to 7% by weight. The zinc salt solution is preferably an aqueous solution containing potassium ions and iodine ions with potassium iodide or the like because zinc ions are easily impregnated. The potassium iodide concentration in the zinc salt solution is preferably about 0.5 to 10% by weight, more preferably 1 to 8% by weight.

  In the zinc impregnation treatment, the temperature of the zinc salt solution is usually about 15 to 85 ° C, preferably 25 to 70 ° C. The immersion time is usually about 1 to 120 seconds, preferably 3 to 90 seconds. In the zinc impregnation treatment, the zinc content in the polyvinyl alcohol film is adjusted to the above range by adjusting the conditions such as the concentration of the zinc salt solution, the immersion temperature of the polyvinyl alcohol film in the zinc salt solution, and the immersion time. adjust. The stage of the zinc impregnation treatment is not particularly limited. In addition, a zinc salt is allowed to coexist in the dyeing bath, the crosslinking bath, and the stretching bath, and, for example, the dyeing step (B-1) in the production method (1) or the iodide compound treatment step in the production method (2) ( B-11) or the ozone treatment step (B-12) may be performed, or may be performed simultaneously with the crosslinking step (C) and the stretching step (D) in the production method (1) or (2).

  After performing each said process, a drying process is finally given and a polarizer is manufactured. In the drying step, a drying time and a drying temperature are appropriately set according to the moisture content required for the obtained polarizer (film). The drying temperature is usually controlled in the range of 20 to 110 ° C. If the drying temperature is too low, the drying time becomes longer, which is not preferable because efficient production cannot be performed. When the drying temperature is too high, the obtained polarizer is deteriorated and deteriorates in terms of optical properties and hue. The heat drying time is usually about 1 to 5 minutes.

  The obtained polarizer can be made into a polarizing plate provided with a transparent protective layer on at least one surface thereof according to a conventional method. The transparent protective layer can be provided as a polymer coating layer or a laminate layer of a transparent protective film. As the transparent polymer or film material for forming the transparent protective film, an appropriate transparent material can be used, but a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property and the like is preferably used. Examples of the material for forming the transparent protective film include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as cellulose diacetate and cellulose triacetate, acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile, Examples thereof include styrene polymers such as styrene copolymers (AS resins), polycarbonate polymers, and the like. 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 polymers that form the transparent protective film. 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.

  Moreover, the polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substitution in the side chain And / or a resin composition containing a thermoplastic resin having unsubstituted phenyl and a nitrile group. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene 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. Since these films have a small phase difference and a small photoelastic coefficient, problems such as unevenness due to the distortion of the polarizing plate can be eliminated, and since the moisture permeability is small, the humidification durability is excellent.

  Although the thickness of a transparent protective layer can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, 5-200 micrometers is more preferable, and 40-100 micrometers is the most preferable.

  Further, it is preferable that the transparent protective layer has as little color as possible. Therefore, Rth = (nx−nz) · d (where nx is the refractive index in the slow axis direction in the plane of the protective layer, nz is the refractive index in the thickness direction of the protective layer, and d is the film thickness). A protective layer having a thickness direction retardation value of −90 nm to +75 nm is preferably used. By using a film having a retardation value (Rth) in the thickness direction of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the protective layer can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.

  As the protective film, a cellulose polymer such as triacetyl cellulose is preferable from the viewpoints of polarization characteristics and durability. A triacetyl cellulose film is particularly preferable. On the other hand, a protective film such as triacetylcellulose has a large retardation value Rth in the thickness direction and has a problem of coloring, but contains an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the resin composition to be used, those having a thickness direction retardation value Rth of 30 nm or less can be used, and coloring can be almost eliminated. In addition, when providing a transparent protective layer on both sides of a polarizer, the transparent protective layer which consists of the same polymer material may be used by the front and back, and the transparent protective layer which consists of a different polymer material etc. may be used.

  The surface of the transparent protective layer to which the polarizer is not adhered may be subjected to a hard coat layer, an antireflection treatment, an antisticking treatment, or a treatment for diffusion or antiglare.

  The hard coat treatment is applied for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective layer with a cured film excellent in hardness, sliding properties, etc. with an appropriate ultraviolet curable resin such as acrylic or silicone It can be formed by a method of adding to the surface of the film. 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 applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. Or by applying a fine concavo-convex structure to the surface of the transparent protective layer by an appropriate method such as a blending method of transparent fine particles. The fine particles to be included in the formation of the surface fine concavo-convex structure are, for example, conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle size of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also 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 antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective layer itself, or can be provided separately from the transparent protective layer as an optical layer.

  An adhesive is used for the adhesion treatment between the polarizer and the transparent protective film. Examples of the adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, and water-based polyesters. The said adhesive agent is normally used as an adhesive agent which consists of aqueous solution, and contains 0.5 to 60 weight% of solid content normally.

  The polarizing plate of the present invention is produced by bonding the transparent protective film and the polarizer using the adhesive. The adhesive may be applied to either the transparent protective film or the polarizer, or to both. After the bonding, a drying process is performed to form an adhesive layer composed of a coating dry layer. Bonding of a polarizer and a transparent protective film can be performed with a roll laminator or the like. The thickness of the adhesive layer is not particularly limited, but is usually about 30 to 1000 nm.

  The polarizing plate of the present invention can be used as an optical film laminated with another optical layer in practical use. The optical layer is not particularly limited. For example, for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), and a viewing angle compensation film. One or more optical layers that may be used can be used. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate or a semi-transmissive reflecting plate is further laminated on the polarizing plate of the present invention, an elliptical polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on the polarizing plate. A wide viewing angle polarizing plate obtained by further laminating a viewing angle compensation film on a plate or a polarizing plate, or a polarizing plate obtained by further laminating a brightness enhancement film on the polarizing plate is preferable.

  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). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. 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.

  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, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. 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.

  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. Specific examples of the retardation plate include a birefringent film obtained by stretching a film made of an appropriate polymer such as polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefins, polyarylate, and polyamide. And an alignment film of a liquid crystal polymer, and a liquid crystal polymer alignment layer supported by a film. 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 elliptical 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 sequentially in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflection type) polarizing plate and a retardation plate. An optical film such as a polarizing plate has an advantage that it can improve the production efficiency of a liquid crystal display device and the like because of excellent quality stability and lamination workability.

  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. As such a viewing angle compensation phase difference plate, for example, a retardation film, an alignment film such as a liquid crystal polymer, or an alignment layer such as a liquid crystal polymer supported on a transparent substrate is used. 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 stretches biaxially in the plane direction. Birefringent polymer film, biaxially stretched film such as polymer with birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, etc. 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.

  Also, from the viewpoint of achieving a wide viewing angle with good visibility, an optically compensated phase difference 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 triacetylcellulose film. A plate can be preferably used.

  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. In addition, 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 enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer.

  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 anisotropies. Such as an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate things, such as a thing, can be used.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers like the above-described 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 transflective 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 other optical films, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics.

  An adhesive layer for adhering to other members such as a liquid crystal cell may be provided on the polarizing plate described above or an optical film in which at least one polarizing plate is laminated. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.

  In addition to the above, in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties and liquid crystal cell warpage due to differences in thermal expansion, etc., as well as formability of liquid crystal display devices with high quality and excellent durability An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  The adhesive layer is, for example, natural or synthetic resins, in particular, tackifier resins, fillers or pigments made of glass fibers, glass beads, metal powders, other inorganic powders, colorants, antioxidants, etc. It may contain an additive to be added to the adhesive layer. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  Attachment of the adhesive layer to one or both sides of the polarizing plate or the optical film can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method in which it is directly attached on a polarizing plate or an optical film by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on a separator according to the above, and this is applied to a polarizing plate or an optical film. The method of moving up is mentioned.

  The pressure-sensitive adhesive layer can be provided on one side or both sides of a polarizing plate or an optical film as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as the adhesion layers of a different composition, a kind, thickness, etc. in the front and back of a polarizing plate or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

  On the exposed surface of the adhesive layer, a separator is temporarily attached and covered for the purpose of preventing contamination until it is put to practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate conventional ones such as those coated with an appropriate release agent such as long-chain alkyl, fluorine-based, or molybdenum sulfide can be used.

  In the present invention, the polarizer, the transparent protective layer, the optical film, etc. that form the polarizing plate described above, and each layer such as the adhesive layer include, for example, salicylic acid ester compounds, benzophenol compounds, benzotriazole compounds, and cyanoacrylates. It may be a compound having an ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorber such as a compound based on nickel or a nickel complex salt compound.

  The polarizing plate or the optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing plate or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses the polarizing plate or optical film by invention, and it can apply according to the former. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which a polarizing plate or an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the polarizing plate or optical film by this invention can be installed in the one side or both sides of a liquid crystal cell. When providing a polarizing plate or an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  Next, an organic electroluminescence 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, Alternatively, a structure having various combinations such as a laminate of such a light emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light emitting layer, and electron injection layer is known. It has been.

  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 plate can be provided between the transparent electrode and the polarizing plate.

  Since the retardation plate and the polarizing plate 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 action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .

  The present invention will be specifically described below with reference to examples and comparative examples.

Example 1
As the raw film, a 75 μm-thick polyvinyl alcohol film (average polymerization degree 2400, saponification degree 99.9 mol%) was used. The following steps were performed on the polyvinyl alcohol film in the same order as in FIG. 3 (however, there was no swelling step).

(Dyeing process)
As a treatment liquid for the dyeing process, a solution was prepared by dissolving ozone generated by the electrolytic method in an aqueous solution containing 3% by weight of potassium iodide by the bubble dissolution method. The ozone concentration of the solution was 3 ppm. In the solution, iodine was generated by the reaction of potassium iodide and ozone. The polyvinyl alcohol film was conveyed and dyed while being uniaxially stretched so that the draw ratio was 2 times the original length while being immersed in the solution adjusted to 30 ° C. for 2 minutes and swollen.

(Crosslinking process)
A boric acid aqueous solution containing 3% by weight of boric acid and 3% by weight of potassium iodide was used as the treatment liquid in the crosslinking step. The treated polyvinyl alcohol film was conveyed and immersed in an aqueous boric acid solution adjusted to 30 ° C. for 30 seconds.

(Stretching process)
A boric acid aqueous solution containing 3% by weight of boric acid and 3% by weight of potassium iodide was used as a treatment liquid in the stretching bridge process. The treated polyvinyl alcohol film was conveyed and uniaxially stretched up to 6 times the total stretch ratio with respect to the original length while being immersed in an aqueous boric acid solution adjusted to 30 ° C. for 30 seconds.

(Washing process)
A potassium iodide aqueous solution containing 3% by weight of potassium iodide was used as a treatment liquid in the washing step. The treated polyvinyl alcohol film was conveyed and immersed in an aqueous potassium iodide solution adjusted to 30 ° C. for 30 seconds.

(Drying process)
Next, the polyvinyl alcohol film was dried at 50 ° C. for 10 minutes to obtain a polarizer.

(Polarizer)
A saponified triacetyl cellulose film was bonded to both surfaces of the obtained polarizer using a polyvinyl alcohol-based adhesive, and then dried at 75 ° C. for 10 minutes to obtain a polarizing plate.

Example 2
The same polyvinyl alcohol film as Example 1 was used as a raw film. The polyvinyl alcohol film was subjected to the following steps in the same order as in FIG. 5 (there was no swelling step, and the crosslinking step and stretching step were performed simultaneously).

(Dyeing process: iodide compound treatment process)
An aqueous solution containing 10% by weight of potassium iodide and 10% by weight of boric acid was prepared as a treatment liquid for the iodide compound treatment step. The polyvinyl alcohol film was transported and immersed in the solution adjusted to 50 ° C. for 1 minute and swollen, and uniaxially stretched so that the stretching ratio was 3 times the original length to obtain a polyvinyl alcohol film. Was impregnated with potassium iodide.

(Dyeing process: ozone treatment process)
An ozone solution was prepared by dissolving ozone generated by the electrolytic method by the bubble dissolution method. The ozone concentration of the solution was 8-9 ppm. The polyvinyl alcohol film treated with the above-described iodide compound was conveyed, immersed in the ozone solution adjusted to 25 ° C. for 1 minute, and iodine was generated by the reaction of potassium iodide and ozone to be dyed.

(Crosslinking process / stretching process)
A boric acid aqueous solution containing 6% by weight of boric acid was used as a treatment liquid in the crosslinking step. The dyed polyvinyl alcohol film was conveyed, immersed in a boric acid aqueous solution adjusted to 50 ° C. for 30 seconds, and uniaxially stretched to a stretch ratio of 2 times (total stretch ratio of 6 times the original length).

(Washing process)
A potassium iodide aqueous solution containing 3% by weight of potassium iodide was used as a treatment liquid in the washing step. The treated polyvinyl alcohol film was conveyed and immersed in an aqueous potassium iodide solution adjusted to 30 ° C. for 30 seconds.

(Drying process)
Next, the polyvinyl alcohol film was dried at 50 ° C. for 10 minutes to obtain a polarizer.

(Polarizer)
A saponified triacetyl cellulose film was bonded to both surfaces of the obtained polarizer in the same manner as in Example 1 using a polyvinyl alcohol-based adhesive, and then dried at 75 ° C. for 10 minutes to obtain a polarizing plate. Got.

Comparative Example 1
In Example 1, a polarizer was produced and a polarizing plate was produced under the same conditions as in Example 1 except that the ozone treatment step was not provided.

  The optical properties of the obtained polarizing plate were measured by the following method. The results are shown in Table 1 and FIG.

(Optical characteristics measurement method)
The polarizing plate is cut at a size of 35 mm × 25 mm so as to be 45 ° with respect to the stretching direction, and single transmittance and parallel transmission are obtained using a spectrophotometer (Murakami Color Research Laboratory: DOT-3). The rate (H ₀ ) and the orthogonal transmittance (H ₉₀ ) were measured, 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

(Absorption spectrum of polarizer)
About the obtained polarizing plate, the absorption spectrum at the time of making a polarized light incident was measured. The absorption spectrum was measured by using a spectrophotometer U4100 manufactured by Hitachi, Ltd. and installing a Glan-Thompson polarizing prism. FIG. 6 shows the absorbance for each wavelength light.
Absorbance = −log ₁₀ (orthogonal transmittance)
That is, the absorbance is 1 when the orthogonal transmittance is 0.1%, the absorbance is 2 when the orthogonal transmittance is 0.01%, and the absorbance is 3 when the orthogonal transmittance is 0.001%. The absorbance is 4 when the orthogonal transmittance is 0.0001%.

  In the examples, the degree of polarization is improved as compared with the comparative examples. This is considered to be because the light absorption characteristics of the polarizing plate (polarizer) were improved as seen in FIG.

It is an example which shows each process in the manufacturing method of the conventional polarizer. It is an example which shows each process in the manufacturing method (1) of the polarizer of this invention. It is an example which shows each process in the manufacturing method (1) of the polarizer of this invention. It is an example which shows each process in the manufacturing method (1) of the polarizer of this invention. It is an example which shows each process in the manufacturing method (2) of the polarizer of this invention. It is a graph which contrasts the light absorbency of the polarizing plate of an Example and a comparative example.

Explanation of symbols

P Polyvinyl alcohol film A Swelling process B Dyeing process B-1 Dyeing process B-11 Iodide compound treatment process (Dyeing process)
B-12 Ozone treatment process (dyeing process)
C Crosslinking process D Stretching process E Cleaning process

Claims (15)

In the manufacturing method of a polarizer which performs at least a dyeing process, a crosslinking process and a stretching process on a polyvinyl alcohol film,
A dyeing process is performed by immersing a polyvinyl alcohol film in a mixed processing solution containing an iodide compound and ozone.   The method for producing a polarizer according to claim 1, wherein the mixed treatment liquid containing an iodide compound and ozone contains a crosslinking agent, and the crosslinking process is performed together with the dyeing process.   The method for producing a polarizer according to claim 1, wherein a stretching process is performed together with the dyeing process. In the manufacturing method of a polarizer which performs at least a dyeing process, a crosslinking process and a stretching process on a polyvinyl alcohol film,
The dyeing process includes an iodide compound treatment process in which a polyvinyl alcohol film is immersed in a treatment liquid containing an iodide compound,
The manufacturing method of the polarizer characterized by performing by the ozone treatment process which immerses a polyvinyl-alcohol-type film in the process liquid containing ozone.   The method for producing a polarizer according to claim 4, wherein an ozone treatment step is performed after the iodide compound treatment step.   The method for producing a polarizer according to claim 5, wherein the treatment liquid containing an iodide compound contains a crosslinking agent.   The method for producing a polarizer according to claim 4, wherein the treatment liquid containing ozone contains a crosslinking agent.   The method for producing a polarizer according to claim 4, wherein a stretching step is performed together with the dyeing step.   The method for producing a polarizer according to claim 1, wherein the iodide compound is potassium iodide.   The method for producing a polarizer according to claim 1, further comprising a swelling step before the dyeing step.   The method for producing a polarizer according to any one of claims 1 to 10, further comprising a washing step after the dyeing step, the crosslinking step, and the stretching step.   The polarizer obtained by the manufacturing method in any one of Claims 1-11.   A polarizing plate provided with a transparent protective layer on at least one surface of the polarizer according to claim 12.   An optical film, wherein at least one of the polarizer according to claim 12 or the polarizing plate according to claim 13 is laminated.   An image display device using at least one polarizer according to claim 12, a polarizing plate according to claim 13, or an optical film according to claim 14.

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