JP2008298871A - 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 satisfactory optical properties. <P>SOLUTION: In the manufacturing method of a polarizer where at least a swelling step, a dyeing step, a crosslinking step and a stretch step are performed to a polyvinyl alcoholic film, the dyeing stage is performed by immersing the polyvinyl alcoholic film into at least two dyeing baths each containing a water solution comprising a dichroic material, also, the bath temperature t°C of at least one dyeing bath in the at least two dyeing baths satisfies 3<t<7, and the bath temperature t°C of the other at least one dyeing bath satisfies 20<t<30. <P>COPYRIGHT: (C)2009,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 polarizer, 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 with which transparent 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, in a method for producing a polarizer that performs a swelling process, an iodine staining process, a crosslinking process, and a stretching process, a method of performing an iodine staining process in two or more stages has been proposed (see Patent Document 1 and Patent Document 2). According to these methods, a polarizer with little dyeing unevenness can be obtained, but further improvement in performance is desired for the polarizer.
JP 2005-173217 A JP 2005-173495 A

  An object of this invention is to provide the manufacturing method of a polarizer with favorable optical characteristics.

  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 polarizer, a 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 swelling process, a dyeing process, a crosslinking process, and a stretching process.
The dyeing step is performed by immersing the polyvinyl alcohol film in a dyeing bath having an aqueous solution containing at least two dichroic materials, and
Of at least two dye baths, the bath temperature t ° C. of at least one dye bath satisfies 3 <t <7, and the bath temperature t ° C. of another at least one dye bath satisfies 20 <t <30. The present invention relates to a method for manufacturing a polarizer.

  In the method for producing a polarizer, it is preferable that at least one dyeing bath satisfying 3 <t <7 and at least one dyeing bath satisfying 20 <t <30 are continuously provided.

  In the method for producing a polarizer, at least one dyeing bath satisfying 3 <t <7 and at least one dyeing bath satisfying 20 <t <30 have an aqueous solution containing the same dichroic material. It is preferable.

  In the method for producing a polarizer, the aqueous solution containing the same type of dichroic material is preferably an iodine dyeing bath having an aqueous solution containing iodine and an iodide compound.

  In the method for producing a polarizer, the aqueous solution containing the same kind of dichroic material preferably has substantially the same concentration of the dichroic material.

  Moreover, this invention relates to the polarizer obtained by the said manufacturing method.

  Moreover, this invention relates to the polarizing plate which provided the transparent protective film in the at least single side | surface of the said 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.

  In the present invention, in the production of the polarizer, at least two dyeing baths for the dyeing process are provided, and the bath temperature of at least one dyeing bath satisfies a low temperature range of 3 <t <7, and at least one other The bath temperature of the dyeing bath is set so as to satisfy a high temperature range of 20 <t <30. In this way, by setting the bath temperature of two or more dyeing baths to different ranges between a predetermined low temperature range and a high temperature range, it is possible to obtain a polarizer in which the degree of polarization and the transmittance are improved in a balanced manner.

  Hereinafter, the present invention will be described with reference to the drawings. In the present invention, the polyvinyl alcohol film is subjected to a swelling process, a dyeing process, a crosslinking process, and a stretching process. FIG. 1 shows an example of a method for producing a polarizer of the present invention. In FIG. 1, the case where the swelling process (A), the dyeing | staining process (B), the bridge | crosslinking process (C), and the extending process (D) are given to the polyvinyl alcohol-type film P in this order is illustrated. Moreover, in FIG. 1, the case where the washing | cleaning process (E) is provided after the extending 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). In the dyeing process (B), the first dyeing process (B1) and the second dyeing process (B2) are continuously provided. In addition, in FIG. 1, although the dyeing | staining process (B) has illustrated the case where two processing baths (dyeing bath) were provided continuously, it concerns on another process between processing baths (dying bath). A treatment bath can also be provided. In addition, as the dyeing step (B), three or more treatment baths (dye baths) can be provided, and these treatment baths (dye baths) may be provided continuously, or treatment baths according to other steps. May be provided.

  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. The degree of polymerization of polyvinyl alcohol is preferably about 100 to 10,000, and more preferably 1,000 to 10,000. 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 method for producing a polarizer of the present invention, as described above, the swelling step (A), the dyeing step (B), the crosslinking step (C), and the stretching step (D) are performed on the polyvinyl alcohol film. First, the dyeing process (B) will be described.

  The dyeing step (B) is performed by immersing the polyvinyl alcohol film in a dyeing bath (b2 in FIG. 1) having a dyeing solution (b1 in FIG. 1). Each dyeing bath is provided continuously. Is preferred. Compared with the case where the two dyeing baths are provided intermittently, when the dyeing bath is provided continuously, it is possible to improve the polarization properties (optical properties) such as the degree of polarization and the transmittance.

  As described above, the bath temperature of the dyeing bath (the bath temperature of the dyeing solution) satisfies the low temperature range in which at least one dyeing bath is 3 <t <7, and the bath temperature of at least one dyeing bath is 20 The bath temperature of each dyeing bath is set so as to satisfy the high temperature range of <t <30. The bath temperature in the low temperature region is preferably 4.5 to 6 ° C. On the other hand, the bath temperature in the high temperature range is preferably 22 to 28 ° C.

  The bath temperature t ° C. of at least two dye baths is such that the bath temperature t ° C. of at least one dye bath of the at least two dye baths satisfies a low temperature range of 3 <t <7, and another at least one dye bath The bath temperature only needs to be set so that the bath temperature t ° C. of the dyeing bath satisfies the high temperature range of 20 <t <30. For example, as shown in FIG. 1, when there are two dyeing baths, one of the dyeing baths satisfies the low temperature range in the first dyeing step (B1) and the second dyeing step (B2). The dyeing bath is set so as to satisfy the high temperature range. From the viewpoint of the swelling property of the polyvinyl alcohol film, it is preferable to set the bath temperature in the first dyeing step (B1) in a high temperature range and the bath temperature in the second dyeing step (B2) in a low temperature range. .

  When three or more dyeing baths are provided as the dyeing step, at least one dyeing bath satisfies the low temperature range, at least one dyeing bath satisfies the high temperature region, and other dyeing baths. Is set to an appropriate temperature.

  In the dyeing bath, an aqueous solution containing a dichroic material is used as a dyeing solution. As the dichroic material, iodine or a dichroic dye is used. An iodine staining solution is preferably used as the staining solution. As the dyeing solution used in the dyeing bath, the same kind or different kinds of dyeing baths can be used, but it is preferable to use an aqueous solution containing the same kind of dichroic material. Therefore, it is preferable to use an iodine dyeing solution for each dyeing bath.

  The iodine staining bath has an iodine staining solution. As the iodine staining solution, an aqueous solution containing iodine ions with iodine and an iodide compound as a dissolution aid is used. 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. Etc. 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 iodine concentration in the iodine dyeing solution is about 0.01 to 1% by weight, preferably 0.02 to 0.5% by weight. The iodide compound concentration is preferably about 0.1 to 10% by weight, more preferably 0.2 to 8% by weight.

  In addition, what was conventionally used for manufacture of a polarizer can be used for a dichroic dye. When the dichroic dye is used, the concentration of the dichroic dye in the dyeing solution is preferably the same as the iodine concentration.

  Moreover, when using the aqueous solution containing the same kind of dichroic material as a dyeing solution used for at least two dyeing baths, it is preferable that the concentration of the dichroic material is approximately the same. For example, it is preferable that the aqueous solution containing iodine and an iodide compound used in an iodine staining bath has the same concentrations of iodine and iodide compound. By setting the concentration to be substantially the same, the iodine content in the polarizer can be improved. The substantially same concentration means that the iodine concentration in the iodine staining solution and the iodine concentration in the iodine staining solution in the first staining step are set as the reference concentration (x1), and the iodine concentration and iodine in the iodine staining solution in the second staining step and thereafter. The case where the contrast concentration (x2) of the chemical compound concentration falls within the range of (x1 / x2) = 1 ± 0.2. (X1 / x2) is preferably 1 ± 0.1, and more preferably 1 (same concentration).

  The immersion time in each dyeing bath is usually about 10 to 300 seconds, preferably 20 to 240 seconds. The immersion time in each dyeing bath may be the same or different.

  The swelling step (A) is performed before the dyeing step (B). 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 FIG. 1). If the main component is water, the treatment liquid 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. If there is swelling unevenness, the portion becomes uneven dyeing in the dyeing step (B), so that swelling unevenness is not generated. 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.

  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) 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 FIG. 1). 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. When the iodide compound is 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 applied together with the dyeing step (B) and 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, it is common to perform stretching after the dyeing step (B). 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. In addition, in FIG. 1, the wet-type extending | stretching method which performs extending | stretching in the process liquid d1 is illustrated.

  When an iodide compound is contained in the treatment liquid used in the wet stretching method, 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 FIG. 1, steps (B) to (D) are performed in this order, but these steps can be performed simultaneously. In addition, the order of these steps can be changed. Further, the steps other than the step (B) can be performed a plurality of times. Specifically, if the crosslinking agent is contained in the bath for performing the dyeing step (B), the dyeing step (B) and the crosslinking step (C) can be performed simultaneously. Furthermore, when extending | stretching at the process, an extending | stretching process (D) can also be performed simultaneously. In FIG. 1, the process (C) and the process (D) are provided with treatment baths, but the process (C) and the process (D) may employ means other than the treatment bath.

  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 (processing liquid e1 in FIG. 1). 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 0.1 to 10% by weight, more preferably 0.2 to 5% 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 it is easy to impregnate zinc ions. The potassium iodide concentration in the zinc salt solution is preferably about 0.1 to 10% by weight, more preferably 0.2 to 5% 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. Further, it may be carried out simultaneously with the dyeing step (B), the crosslinking step (C), and the stretching step (D) by allowing a zinc salt to coexist in the dyeing bath, the crosslinking bath, and the stretching bath.

  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 the polarizing plate which provided the transparent protective film in the at least single side | surface according to the conventional method. As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples thereof include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. In addition, a transparent protective film is usually bonded to the polarizer by an adhesive layer. As the transparent protective film, thermosetting such as (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone-based, etc. Resin or ultraviolet curable resin can be used. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  Moreover, as a transparent protective film, 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) Resin compositions containing thermoplastic resins having substituted and / or unsubstituted phenyl and nitrile groups in the side chains. 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 film 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, and 5-200 micrometers is more preferable. The transparent protective film is particularly suitable when the thickness is 5 to 150 μm.

  In addition, when providing a transparent protective film on both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used.

  As the transparent protective film of the present invention, it is preferable to use at least one selected from cellulose resin, polycarbonate resin, cyclic polyolefin resin, and (meth) acrylic resin.

  Cellulose resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, dipropionyl cellulose and the like. Among these, triacetyl cellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available products of triacetyl cellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, and “UZ” manufactured by Fujifilm Corporation. -TAC "and" KC series "manufactured by Konica. In general, these triacetyl celluloses have an in-plane retardation (Re) of almost zero, but a thickness direction retardation (Rth) of about 60 nm.

  In addition, the cellulose resin film with a small thickness direction phase difference is obtained by processing the said cellulose resin, for example. For example, a base film such as polyethylene terephthalate, polypropylene, and stainless steel coated with a solvent such as cyclopentanone and methyl ethyl ketone is bonded to a general cellulose film and dried by heating (for example, at 80 to 150 ° C. for about 3 to 10 minutes). ) And then peeling the base film; a solution obtained by dissolving norbornene resin, (meth) acrylic resin, etc. in a solvent such as cyclopentanone, methyl ethyl ketone, etc. is applied to a general cellulose resin film and dried by heating ( For example, a method of peeling the coated film after 80 to 150 ° C. for about 3 to 10 minutes is mentioned.

  Moreover, as a cellulose resin film with a small thickness direction retardation, the fatty acid cellulose resin film which controlled the fat substitution degree can be used. Generally used triacetyl cellulose has an acetic acid substitution degree of about 2.8. Preferably, the Rth can be reduced by controlling the acetic acid substitution degree to 1.8 to 2.7. Rth can be controlled to be small by adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide, acetyltriethyl citrate to the fatty acid-substituted cellulose resin. The addition amount of the plasticizer is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, and still more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the fatty acid cellulose resin.

  Specific examples of the cyclic polyolefin resin are preferably norbornene resins. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And graft polymers obtained by modifying them with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as the cyclic polyolefin resin. As specific examples, trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, product names “ARTON” manufactured by JSR Corporation, “TOPAS” manufactured by TICONA, and product names manufactured by Mitsui Chemicals, Inc. “APEL”.

  The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. When Tg is 115 ° C. or higher, the polarizing plate can be excellent in durability. Although the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability. From (meth) acrylic resin, a film having in-plane retardation (Re) and thickness direction retardation (Rth) of almost zero can be obtained.

  As the (meth) acrylic resin, any appropriate (meth) acrylic resin can be adopted as long as the effects of the present invention are not impaired. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferably, poly (meth) acrylate C1-6 alkyl such as poly (meth) acrylate methyl is used. More preferred is a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

  Specific examples of (meth) acrylic resins include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. And a high Tg (meth) acrylic resin system obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure can also be used. It is because it has high mechanical strength by high heat resistance, high transparency, and biaxial stretching.

  Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. Examples thereof include (meth) acrylic resins having a lactone ring structure described in Japanese Patent No. 146084.

  The (meth) acrylic resin having a lactone ring structure preferably has a ring pseudo structure represented by the following general formula (Formula 1).

^Wherein, R 1, ^{R 2} and ^{R 3} each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The content ratio of the lactone ring structure represented by the general formula (Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is preferably 5 to 90% by weight, more preferably 10 to 70% by weight, More preferably, it is 10 to 60% by weight, and particularly preferably 10 to 50% by weight. When the content of the lactone ring structure represented by the general formula (Chemical Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is less than 5% by weight, the heat resistance, solvent resistance, and surface hardness are low. May be insufficient. If the content of the lactone ring structure represented by the general formula (Chemical Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is more than 90% by weight, molding processability may be poor.

  The (meth) acrylic resin having a lactone ring structure has a mass average molecular weight (sometimes referred to as a weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably. Is 50,000 to 500,000. If the mass average molecular weight is out of the above range, it is not preferable from the viewpoint of molding processability.

  The (meth) acrylic resin having a lactone ring structure preferably has a Tg of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. Since Tg is 115 ° C. or higher, for example, when incorporated into a polarizing plate as a transparent protective film, it has excellent durability. Although the upper limit of Tg of the (meth) acrylic resin having the lactone ring structure is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability and the like.

  The (meth) acrylic resin having a lactone ring structure is preferably as the total light transmittance of a molded product obtained by injection molding measured by a method according to ASTM-D-1003 is higher, preferably 85. % Or more, more preferably 88% or more, and still more preferably 90% or more. The total light transmittance is a measure of transparency. If the total light transmittance is less than 85%, the transparency may be lowered.

  As the transparent protective film, one having a front phase difference of less than 40 nm and a thickness direction retardation of less than 80 nm is usually used. The front phase difference Re is represented by Re = (nx−ny) × d. The thickness direction retardation Rth is represented by Rth = (nx−nz) × d. The Nz coefficient is represented by Nz = (nx−nz) / (nx−ny). [However, the refractive indexes in the slow axis direction, the fast axis direction, and the thickness direction of the film are nx, ny, and nz, respectively, and d (nm) is the thickness of the film. The slow axis direction is the direction that maximizes the refractive index in the film plane. ]. In addition, it is preferable that a transparent protective film has as little color as possible. A protective film having a thickness direction retardation value of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the transparent protective film 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.

  On the other hand, as the transparent protective film, a phase difference plate having a phase difference with a front phase difference of 40 nm or more and / or a thickness direction retardation of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate functions also as a transparent protective film, so that the thickness can be reduced.

  Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 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, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or any of these binary, ternary copolymers, graft copolymers Examples thereof include polymers and blends. These polymer materials become an oriented product (stretched film) by stretching or the like.

  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. . Specific examples of the main chain type liquid crystal polymer include a nematic alignment polyester liquid crystal polymer, a discotic polymer, and a cholesteric polymer having a structure in which a mesogen group is bonded at a spacer portion that imparts flexibility. Specific examples of the side chain type liquid crystal polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment-providing para-substitution through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogenic part composed of a cyclic compound unit. These liquid crystal polymers can be prepared by, for example, applying a solution of a liquid crystalline polymer on an alignment surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. This is done by developing and heat treatment.

  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 liquid crystal layers and compensation of viewing angle, etc. It may be one in which retardation plates are stacked and optical characteristics such as retardation are controlled.

  The retardation plate has a relationship of nx = ny> nz, nx> ny> nz, nx> ny = nz, nx> nz> ny, nz = nx> ny, nz> nx> ny, nz> nx = ny. What is satisfactory is selected and used according to various applications. Note that ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same.

  For example, in a phase difference plate that satisfies nx> ny> nz, a surface plate having a front phase difference of 40 to 100 nm, a thickness direction phase difference of 100 to 320 nm, and an Nz coefficient of 1.8 to 4.5 is used. Is preferred. For example, in a retardation plate (positive A plate) that satisfies nx> ny = nz, it is preferable to use a retardation plate that satisfies a front phase difference of 100 to 200 nm. For example, for a retardation plate (negative A plate) that satisfies nz = nx> ny, it is preferable to use a retardation plate that satisfies a front phase difference of 100 to 200 nm. For example, in a retardation plate satisfying nx> nz> ny, it is preferable to use a retardation plate having a front phase difference of 150 to 300 nm and an Nz coefficient exceeding 0 to 0.7. Further, as described above, for example, nx = ny> nz, nz> nx> ny, or nz> nx = ny can be used.

  The transparent protective film can be appropriately selected according to the applied liquid crystal display device. For example, in the case of VA (including Vertical Alignment, MVA, and PVA), it is desirable that at least one of the polarizing plates (cell side) has a retardation. As specific phase differences, it is desirable that Re = 0 to 240 nm and Rth = 0 to 500 nm. In terms of the three-dimensional refractive index, nx> ny = nz, nx> ny> nz, nx> nz> ny, nx = ny> nz (uniaxial, biaxial, Z-ized, negative C plate) is desirable. When polarizing plates are used above and below the liquid crystal cell, both the upper and lower sides of the liquid crystal cell may have a phase difference, or any one of the upper and lower transparent protective films may have a phase difference.

  For example, in the case of IPS (including In-Plane Switching, FFS), both cases where the transparent protective film on one side of the polarizing plate has a phase difference and does not have a phase difference can be used. For example, when there is no phase difference, it is desirable that the liquid crystal cell does not have a phase difference both above and below (cell side). When the liquid crystal cell has a phase difference, it is desirable that the liquid crystal cell has a phase difference on both the upper and lower sides. When there is no phase difference, or when the A plate is on the upper side and the positive C plate is on the lower side). When it has a phase difference, it is desirable that Re = −500 to 500 nm and Rth = −500 to 500 nm. In terms of the three-dimensional refractive index, nx> ny = nz, nx> nz> ny, nz> nx = ny, nz> nx> ny (uniaxial, Z-ized, positive C plate, positive A plate) are desirable.

  In addition, the film which has the said phase difference can be separately bonded to the transparent protective film which does not have a phase difference, and the said function can be provided.

  The transparent protective film may be subjected to a surface modification treatment before coating with an adhesive. Specific examples of the treatment include corona treatment, plasma treatment, primer treatment, and saponification treatment.

  The surface of the transparent protective film 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 film with a cured film excellent in hardness, sliding properties, etc. by an appropriate ultraviolet curable resin such as acrylic or silicone is used. 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. In addition, the sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer (for example, a backlight-side diffusion plate).

  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. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a blending method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle diameter of 0.5 to 20 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles made of a crosslinked or uncrosslinked polymer, etc. 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 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 film itself, or can be provided separately from the transparent protective film 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. In addition to the above, examples of the adhesive between the polarizer and the transparent protective film include an ultraviolet curable adhesive and an electron beam curable adhesive. The electron beam curable polarizing plate adhesive exhibits suitable adhesion to the various transparent protective films. In particular, it exhibits good adhesion even with respect to acrylic resins for which it was difficult to satisfy the adhesion.

  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 side of the polarizing plate via a transparent protective film or the like, if 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. Furthermore, 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 film, the optical film, and the like that form the polarizing plate described above, and each layer such as an adhesive layer include, for example, a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, and a cyanoacrylate. 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 reflecting plate 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. In general, 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.

(Swelling process)
Pure water was used as the treatment liquid in the swelling process. The treated polyvinyl alcohol film was transported and uniaxially stretched so that the stretching ratio was 3 times the original length while being immersed in pure water adjusted to 30 ° C. for 1 minute and swollen.

(First dyeing process)
As the treatment liquid in the first dyeing step, an iodine dyeing solution adjusted to a ratio of iodine: potassium iodide: water = 1: 10: 2000 (weight ratio) was used. The treated polyvinyl alcohol film was transported and immersed in an iodine staining solution adjusted to 25 ° C. for 1 minute for staining.

(Second dyeing process)
As the treatment liquid in the second dyeing step, the same iodine dyeing solution in the first dyeing step was used. The treated polyvinyl alcohol film was transported and immersed in an iodine staining solution adjusted to 4.5 ° C. for 1 minute for staining.

(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 the 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.

Comparative Example 1
In Example 1, a polarizer was produced under the same conditions as Example 1 except that the second dyeing step was not performed.

Examples 2-6, Comparative Examples 2-10
In Example 1, a polarizer was produced under the same conditions as in Example 1 except that the bath temperature (temperature of the iodine dyeing solution) in the first dyeing process and the second dyeing process was changed as shown in Table 1.

  The optical properties of the obtained polarizer were measured by the following method.

(Optical characteristics measurement method)
The optical properties of the polarizer were measured with a spectrophotometer with an integrating sphere (V7100 manufactured by JASCO Corporation). The transmittance for each linearly polarized light was measured with 100% of the completely polarized light obtained through the Grantera-prism polarizer. The single transmittance (Ts), parallel transmittance (H ₀ ), and orthogonal transmittance (H ₉₀ ) were measured at a wavelength of 550 nm, and the degree of polarization (P) was determined from the values by the following formula. Note that these transmittances are Y values obtained by correcting the visibility with the JlSZ 8701's 2-degree field of view (C light source). Polarization degree (%) = {(H ₀ −H ₉₀ ) / (H ₀ + H ₉₀ )} ^1/2 × 100

  FIG. 2 shows the unit transmittance (Ts) and the degree of polarization (P) of the polarizers obtained in Examples 1 to 6 and Comparative Example 1, with the unit transmittance (Ts) on the horizontal axis and the degree of polarization (P). Is a graph plotted with the ordinate as the vertical axis. FIG. 3 is a graph created for the polarizers obtained in Comparative Examples 2-6 and Comparative Example 1, and FIG. 4 is a graph created for the polarizers obtained in Comparative Examples 7-10 and Comparative Example 1 in the same manner as described above. is there.

  In FIG. 2 thru | or 4, about the comparative example 1 (sample number 7), the plotted point is represented by the curve. In FIG. 2, Example 1 has 4 samples, Example 2 has 6 samples, Example 3 has 4 samples, Example 4 has 3 samples, Example 5 has 3 samples, and Example 6 has 6 samples. 4. In FIG. 3, Comparative Example 2 has 5 samples, Comparative Example 3 has 4 samples, Comparative Example 4 has 3 samples, Comparative Example 5 has 3 samples, and Comparative Example 6 has 3 samples. In FIG. 4, the comparative example 7 has three samples, the comparative example 8 has three samples, the comparative example 9 has three samples, and the comparative example 10 has three samples. In the graphs of FIGS. 2 to 4, it is desirable that the single transmittance (Ts) on the horizontal axis and the degree of polarization (P) on the vertical axis are both high. Therefore, if Comparative Example 1 is used as a standard, it relates to Comparative Example 1. Preferably there is a plot on the right or top side of the curve. In FIG. 2, the plots of each example are on the right side or the upper side of the curve, and it can be seen that a polarizer having a high transmittance and a high degree of polarization is obtained. On the other hand, in FIGS. 3 and 4, the plots of the comparative examples are all on the curve or on the same side, or on the left side or the lower side, which is sufficient in terms of transmittance and degree of polarization compared to the examples. Absent.

It is an example which shows each process in the manufacturing method of the polarizer of the present invention. Regarding the single transmittance (Ts) and polarization degree (P) of the polarizers obtained in Examples 1 to 6 and Comparative Example 1, the single transmittance (Ts) is on the horizontal axis and the polarization degree (P) is on the vertical axis. This is a plotted graph. Regarding the single transmittance (Ts) and polarization degree (P) of the polarizers obtained in Comparative Examples 2 to 6 and Comparative Example 1, the single transmittance (Ts) is on the horizontal axis and the polarization degree (P) is on the vertical axis. This is a plotted graph. Regarding the single transmittance (Ts) and polarization degree (P) of the polarizers obtained in Comparative Examples 7 to 10 and Comparative Example 1, the single transmittance (Ts) is on the horizontal axis and the polarization degree (P) is on the vertical axis. This is a plotted graph.

Explanation of symbols

P Polyvinyl alcohol film A Swelling process B Dyeing process C Crosslinking process D Stretching process E Washing process

Claims (9)

In the method for producing a polarizer, the polyvinyl alcohol film is subjected to at least a swelling process, a dyeing process, a crosslinking process, and a stretching process.
The dyeing step is performed by immersing the polyvinyl alcohol film in a dyeing bath having an aqueous solution containing at least two dichroic materials, and
Of at least two dye baths, the bath temperature t ° C. of at least one dye bath satisfies 3 <t <7, and the bath temperature t ° C. of another at least one dye bath satisfies 20 <t <30. A method for producing a polarizer, comprising:   2. The polarizer according to claim 1, wherein at least one dyeing bath satisfying 3 <t <7 and at least one dyeing bath satisfying 20 <t <30 are continuously provided. Production method.   The at least one dyeing bath satisfying 3 <t <7 and the at least one dyeing bath satisfying 20 <t <30 have an aqueous solution containing the same dichroic material. Or the manufacturing method of the polarizer of 2.   The method for producing a polarizer according to claim 3, wherein the aqueous solution containing the same type of dichroic material is an iodine dyeing bath having an aqueous solution containing iodine and an iodide compound.   5. The method for producing a polarizer according to claim 3, wherein the aqueous solution containing the same kind of dichroic material has substantially the same concentration of the dichroic material.   The polarizer obtained by the manufacturing method in any one of Claims 1-5.   The polarizing plate which provided the transparent protective film in the at least single side | surface of the polarizer of Claim 6.   An optical film, wherein at least one of the polarizer according to claim 6 or the polarizing plate according to claim 7 is laminated. An image display device using at least one of the polarizer according to claim 6, the polarizing plate according to claim 7, or the optical film according to claim 8.