JP2017129886A - Method for storing polarizing plate, method for eliminating or reducing corrugation defects of polarizing plate, and method for manufacturing polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing plate storing method and a polarizing plate manufacturing method capable of maintaining a state in which there is substantially no corrugation defect or suppressing corrugation defects to a degree that does not cause problems such as air bubble contamination and associated low visibility.SOLUTION: A polarizing plate storing method and a polarizing plate manufacturing method include the steps of: preparing a polarizing plate including a polarizer and a protection film laminated thereon and causing a corrugation defect with a height exceeding 3 mm on any side or causing three or more corrugation defects on any side when stored for a week under an environment of a temperature of 23°C and a relative humidity of 55%; and storing the polarizing plate in an environment under which a moisture percentage after storing the polarizing plate is lower than the moisture percentage when storing the polarizing plate for a week under the environment of a temperature of 23°C and a relative humidity of 55%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for storing a polarizing plate suitably used for an image display device such as a liquid crystal display device, a method for eliminating or reducing wavy defects of the polarizing plate, and a method for producing a polarizing plate.

  As a liquid crystal display device, a liquid crystal panel comprising a liquid crystal cell and a polarizing plate bonded to the front and back of the liquid crystal cell, and a housing for housing the liquid crystal panel, a frame for covering the periphery of the liquid crystal panel and the front side polarizing plate is provided. Those provided on the front side of the housing are widely used. This frame is required to be narrower in terms of design and the like.

  On the other hand, the polarizing plate generally has a laminated structure in which a protective film is bonded to one or both sides of a polarizer via an adhesive layer (for example, Patent Document 1). The polarizer and the protective film are usually made of different materials. For this reason, the polarizing plate may be deformed in a wavy shape (also referred to as wave curl) during storage after manufacture. In the present specification, such an appearance defect that a polarizing plate is deformed into a wave shape is referred to as a “waving defect”.

JP 2004-245925 A

  Rippling defects tend to be noticeable in the height and / or number of undulations that occur, especially when the polarizer size is large. For example, when a wavy defect occurs in the polarizing plate, for example, when applied to a liquid crystal display device, the adhesive layer and the liquid crystal cell are bonded when the polarizing plate and the liquid crystal cell are bonded via the adhesive layer. Bubbles are likely to be mixed into the bonding interface, and particularly the peripheral portion of the bonding interface or the vicinity thereof. When this bubble is generated in the image display area of the liquid crystal panel, it becomes a bright spot when turned on, and the visibility can be lowered. Accordingly, the polarizing plate is applied to a liquid crystal display device using a casing having a narrow frame width as described above, and the polarizing plate in which the region closer to the peripheral edge of the polarizing plate is used for the image display region is a liquid crystal cell. It is required that there is no undulation defect at the time of bonding, or that the undulation defect is sufficiently reduced to such an extent that the above-described bubble mixing and the accompanying visibility degradation problem do not occur.

  Therefore, the present invention aims to provide a polarizing plate storage method that can maintain a state substantially free of undulation defects or can suppress undulation defects to such an extent that the above-described bubble mixing and the accompanying visibility degradation problems do not occur. And Another object of the present invention is to provide a method that can substantially eliminate the undulation defect of the polarizing plate that has caused the undulation defect, or suppress the undulation defect to such an extent that the above problem does not occur. Still another object of the present invention is to provide a method for producing a polarizing plate that is substantially free of wavy defects or in which wavy defects are suppressed to such an extent that the above-mentioned problem does not occur.

  The present invention provides a method for storing a polarizing plate, a method for eliminating or reducing wavy defects of the polarizing plate, and a method for producing a polarizing plate, as described below.

[1] A polarizing plate comprising a polarizer and at least one protective film laminated thereon, and when stored for 1 week in an environment of 23 ° C. and 55% relative humidity, the height of either side is Preparing a polarizing plate that generates a undulation defect exceeding 3 mm or three or more undulation defects on any side;
A step of storing the polarizing plate in an environment where the polarizing plate moisture content after storage is lower than the polarizing plate moisture content when stored for one week in an environment of 23 ° C. and 55% relative humidity;
A method for storing a polarizing plate, comprising:

[2] A polarizing plate comprising a polarizer and at least one protective film laminated thereon, and has a wavy defect with a height exceeding 3 mm on any side, or three on any side Preparing a polarizing plate having the above undulating defects;
Storing the polarizing plate in an environment where the polarizing plate moisture after storage is lower than the polarizing plate moisture before storage;
The method of eliminating or reducing the wavy defect which the polarizing plate contains.

[3] A polarizing plate comprising a polarizer and at least one protective film laminated thereon, and when stored for one week in an environment at 23 ° C. and a relative humidity of 55%, the height of either side is Preparing a polarizing plate that generates a undulation defect exceeding 3 mm or three or more undulation defects on any side;
A step of storing the polarizing plate in an environment where the polarizing plate moisture content after storage is lower than the polarizing plate moisture content when stored for one week in an environment of 23 ° C. and 55% relative humidity;
The manufacturing method of a polarizing plate containing.

[4] A polarizing plate including a polarizer and at least one protective film laminated thereon, and has a wavy defect whose height exceeds 3 mm on any side, or three on any side Preparing a polarizing plate having the above undulating defects;
Storing the polarizing plate in an environment where the polarizing plate moisture after storage is lower than the polarizing plate moisture before storage;
The manufacturing method of a polarizing plate containing.

  [5] The method according to any one of [1] to [4], wherein the storing step includes a step of storing the polarizing plate in an environment having a relative humidity of 30 to 50%.

  [6] The method according to any one of [1] to [5], wherein the polarizing plate is stored in a sealed container in the storing step.

  [7] The method according to any one of [1] to [5], wherein in the storing step, the polarizing plate is stored in a sealed container containing a dehumidifying agent.

  [8] The method according to any one of [1] to [7], wherein the polarizing plate prepared in the preparing step has a rectangular shape with a long side of 700 mm or more and a short side of 400 mm or more.

  [9] At least one of the protective films is any one of [1] to [8], which is a thermoplastic resin film selected from the group consisting of a polyolefin resin film and a (meth) acrylic resin film. the method of.

  According to the present invention, for example, there is substantially no undulation defect at the time of pasting with another member such as a liquid crystal cell, or the undulation defect does not cause the above-described bubble mixing and the accompanying visibility degradation problem. A polarizing plate suppressed to a certain degree can be provided.

It is a side view which shows an example of the polarizing plate which has a wavy defect. It is a schematic sectional drawing which shows an example of the laminated constitution of the polarizing plate provided to the storage method of this invention, the elimination or reduction method of a wavy defect, and the manufacturing method of a polarizing plate.

<Storage method of polarizing plate>
The method for storing a polarizing plate according to the present invention includes the following steps:
(1) A polarizing plate comprising a polarizer and at least one protective film laminated thereon, and when stored for 1 week in an environment of 23 ° C. and a relative humidity of 55%, the height on either side is A step of preparing a polarizing plate A that generates a undulation defect exceeding 3 mm or three or more undulation defects on any side; and (2) a polarizing plate moisture content after storage is 23 ° C. and a relative humidity of 55% A step of storing the polarizing plate A in an environment that is lower than the moisture content of the polarizing plate when stored for one week in the environment of
including. Hereinafter, each step will be described.

(1) Step of Preparing Polarizing Plate A Polarizing plate A used in the polarizing plate storage method according to the present invention is corrugated with the problem of mixing of bubbles as described above and the accompanying visibility deterioration under normal storage conditions. It is a polarizing plate that is prone to defects. Specifically, referring to FIG. 1, when stored for one week in an environment of 23 ° C. and 55% relative humidity, a wave with a height exceeding 3 mm on either side. It is a polarizing plate that causes defects or three or more wavy defects on either side. A polarizing plate having such wavy defects is very likely to cause the above problem. FIG. 1 is a side view showing an example of a polarizing plate having wavy defects, and shows a side where a wavy defect occurs in the polarizing plate. In the example of FIG. 1, the side has five undulating defects (the wavy deformations W, X and Z in FIG. 1), one of which is a undulating defect whose height exceeds 3 mm (FIG. 1). Inside wavy deformation W).

  The height of the undulation defect is the height from the plane table to the top of the undulation defect when the polarizing plate is placed on the plane table. The said height is measured in the edge | side (edge part) of a polarizing plate. The number of undulating defects is substantially the number of undulating defects. Specifically, when the polarizing plate is placed on a flat table, the height is 0.5 mm or more from the flat table. It is the number of defects. Therefore, a wave-like deformation whose height is less than 0.5 mm from the flat table as indicated by Y shown in FIG. 1 is not counted as a wavy defect. The wave-shaped deformation Z shown in FIG. 1 has a height of 0.5 mm and is counted as a undulating defect. The number of undulation defects is also measured at the sides (edges) of the polarizing plate. Note that, as indicated by K in FIG. 1, the end (corner) of the side (end) of the polarizing plate is not counted as a wavy defect even if it is lifted from the flat table.

  The shape of the polarizing plate A is not particularly limited, but is preferably a rectangular (typically rectangular) polarizing plate having a long side of 700 mm or more and a short side of 400 mm or more. In a polarizing plate having a smaller size, wavy defects are generally less likely to be a problem. The polarizing plate A which is a sheet can be obtained, for example, by cutting a polarizing plate manufactured as a long body. In this specification, “preparing polarizing plate A” includes obtaining (manufacturing) polarizing plate A.

  The layer configuration of the polarizing plate A is not particularly limited as long as it includes a polarizer and at least one protective film laminated thereon, but at the time of storage before being put to practical use, for example, in a polarizing plate for a liquid crystal display device During storage before being bonded to the liquid crystal cell, the polarizing plate generally has an adhesive layer for bonding to the liquid crystal cell, and protects the surface (outer surface) of the adhesive layer. Since it is common to provide a protective film (surface protective film) for protecting the separate film for protecting the surface (outer surface) of the protective film, the polarizing plate A, in addition to the polarizer and the protective film, It is preferable to have an adhesive layer, a separate film, and a protect film.

  An example of the layer structure of the polarizing plate A is shown in FIG. The polarizing plate 1 shown in FIG. 2 includes a polarizer 10; a first protective film 20 that is bonded to one surface of the polarizer 10; a second protective film 30 that is bonded to the other surface of the polarizer 10; A pressure-sensitive adhesive layer 40 laminated on the outer surface of the second protective film 30; a separate film 50 laminated on the outer surface of the pressure-sensitive adhesive layer 40; and a protective film 60 laminated on the outer surface of the first protective film 20.

  The polarizer 10 is an optical film having a property of absorbing linearly polarized light having a vibration plane parallel to the optical axis and transmitting linearly polarized light having a vibration plane perpendicular to the optical axis. For example, the polarizer 10 is uniaxially stretched and has two colors. It can be a polyvinyl alcohol-based resin film in which a functional dye is adsorbed and oriented. As the dichroic dye, iodine or a dichroic organic dye is used. The polyvinyl alcohol-based resin constituting the polarizer 10 includes polyvinyl alcohol, which is a saponified product of polyvinyl acetate, and a copolymer of vinyl acetate and other monomers copolymerizable therewith (for example, ethylene and unsaturated carboxylic acid). It may be a vinyl alcohol copolymer which is a saponified product. The thickness of the polarizer 10 is usually about 5 to 40 μm.

  The polarizer 10 includes a step of uniaxially stretching a polyvinyl alcohol-based resin film, a step of dyeing the polyvinyl alcohol-based resin film with a dichroic dye and adsorbing the dichroic dye, and polyvinyl alcohol on which the dichroic dye is adsorbed. The resin film can be manufactured through a step of treating with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution. The dichroic dye can be dyed by immersing the film in an aqueous solution containing the dichroic dye, and the treatment with the boric acid aqueous solution can be performed by immersing the film in the boric acid aqueous solution.

  Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing the dichroic dye. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, you may uniaxially stretch in these several steps.

  The 1st and 2nd protective films 20 and 30 can be a thermoplastic resin film which has translucency (preferably optically transparent). Specific examples of the thermoplastic resin include a polyolefin resin such as a chain polyolefin resin and a cyclic polyolefin resin (such as a norbornene resin); a polyester resin such as polyethylene terephthalate; a methyl methacrylate resin (meta ) Acrylic resins; Cellulose resins such as cellulose triacetate and cellulose diacetate; Polycarbonate resins; Polyvinyl alcohol resins; Polyvinyl acetate resins; Polyarylate resins; Polystyrene resins; Polyethersulfone resins; Resin; polyamide resin; polyimide resin; and mixtures and copolymers thereof. In this specification, “(meth) acrylic resin” represents at least one selected from the group consisting of acrylic resins and methacrylic resins. The same applies to other terms with “(meta)”. At least one of the protective films of the polarizing plate A is preferably a thermoplastic resin film selected from the group consisting of a polyolefin resin film and a (meth) acrylic resin film.

  The 1st protective film 20 and the 2nd protective film 30 may be comprised with the same kind of thermoplastic resin, and may be comprised with a different kind of thermoplastic resin. The thickness of the 1st and 2nd protective films 20 and 30 is about 5-200 micrometers, for example, Preferably it is 10-150 micrometers, More preferably, it is 20-100 micrometers.

  The pressure-sensitive adhesive layer 40 is a layer for bonding the polarizing plate to another member such as a liquid crystal cell. Examples of the adhesive constituting the adhesive layer 40 include (meth) acrylic adhesives, urethane adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, polyether adhesives, and fluorine adhesives. Agents, rubber adhesives, and the like. Among these, a (meth) acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, and the like. The thickness of the pressure-sensitive adhesive layer 40 is usually 2 to 40 μm.

  The separate film 50 and the protect film 60 are each provided for the purpose of temporarily protecting the pressure-sensitive adhesive layer 40 and the first protective film 20 when the polarizing plate is stored, transported, or inspected. The separate film 50 that protects the pressure-sensitive adhesive layer 40 is peeled and removed immediately before the polarizing plate 1 is put to practical use (for example, bonded to another member such as a liquid crystal cell). The protective film 60 is usually peeled and removed together with the pressure-sensitive adhesive layer after the polarizing plate 1 is put to practical use (for example, bonded to another member such as a liquid crystal cell).

  The separate film 50 is usually composed of a thermoplastic resin film that has been subjected to a release treatment on one side, and the release treatment surface is bonded to the adhesive layer 40. The protect film 60 is usually configured by providing an adhesive layer on one side of a thermoplastic resin film. The thermoplastic resin constituting the separate film 50 and the protect film 60 may be, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, or a polyester resin such as polyethylene terephthalate or polyethylene naphthalate. it can. Regarding the pressure-sensitive adhesive layer that the protective film 60 has, the description of the pressure-sensitive adhesive layer 40 described above is cited.

  The layer configuration of the polarizing plate A is not limited to the example shown in FIG. 2, and for example, the following layer configuration may be used.

[A] Configuration in which any one or more of the pressure-sensitive adhesive layer 40, the separate film 50, and the protect film 60 are omitted;
[B] a configuration in which one of the first protective film 20 and the second protective film 30 is omitted;
[C] a configuration using an optical compensation film such as a retardation film as the second protective film 30;
[D] A configuration having an optical compensation film such as a retardation film in addition to the first protective film 20 and the second protective film 30.

  An example of the above [b] is a configuration in which the second protective film 30 is omitted, and a preferred specific example thereof is that the pressure-sensitive adhesive layer 40 is directly laminated on the surface of the polarizer 10 opposite to the protective film 60, The protective film 60 / first protective film 20 / polarizer 10 / adhesive layer 40 / separate film 50 are layered.

  A preferred specific example of the above [c] is a protective film 60 / first protective film 20 / polarizer 10 / retardation film (second protective film 30) / adhesive layer 40 / separate film 50 layer structure. It is. A preferred specific example of the above [d] is a protective film 60 / first protective film 20 / polarizer 10 / second protective film 30 / retardation film / adhesive layer 40 / separate film 50 layer structure. is there.

  The retardation film is an optical film having optical anisotropy such as uniaxial or biaxial, and can be, for example, a stretched film of a thermoplastic resin. The thermoplastic resin can be the one exemplified above for the first and second protective films 20 and 30, as well as polyvinylidene fluoride / polymethyl methacrylate copolymer, liquid crystal polyester, acetyl cellulose, ethylene-vinyl acetate. A saponified copolymer, polyvinyl chloride, or the like can also be used. The draw ratio is usually about 1.01 to 6 times.

  The polarizer 10, the first protective film 20 and the second protective film 30 (including the case of being a retardation film) are an adhesive or a pressure-sensitive adhesive (for this pressure-sensitive adhesive, the pressure-sensitive adhesive layer 40 described above). The description is quoted.). As the adhesive, an aqueous adhesive, that is, an adhesive component dissolved in water or dispersed in water, or an active energy ray-curable adhesive can be used.

  The adhesive component of the water-based adhesive can be, for example, a polyvinyl alcohol resin or a urethane resin. The active energy ray-curable adhesive can be, for example, a curable composition containing an active energy ray-curable compound such as an epoxy compound or a (meth) acrylic compound and a polymerization initiator. The active energy ray-curable adhesive can be a solventless adhesive, but can also contain an organic solvent (a solvent other than water). If a solventless type adhesive is used, a drying process for removing the solvent becomes unnecessary. When an active energy ray-curable adhesive is used, an adhesive layer is applied by irradiating active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, preferably ultraviolet rays, after the film is bonded through the adhesive. Is cured.

  When using a water-based adhesive, the film laminated body bonded through the adhesive is usually subjected to a drying treatment to remove moisture from the adhesive layer. In this case, when the film bonded to the polarizer 10 is a thermoplastic resin film having low moisture permeability, the drying time becomes long and the productivity is lowered, or the water in the aqueous adhesive cannot be sufficiently dried. In addition, the adhesive strength may decrease. In this respect, the active energy ray-curable adhesive is advantageous because the above-described problem does not occur even when a thermoplastic resin film having low moisture permeability is bonded.

  When a thermoplastic resin film having low moisture permeability is bonded to the polarizer 10, the difference in moisture content from the polarizer 10 increases, and the waviness defect of the polarizing plate tends to increase. Therefore, the present invention is particularly effective when a thermoplastic resin film having a low moisture permeability is used as the first protective film 20 and / or the second protective film 30 (including the case of being a retardation film). Specific examples of thermoplastic resin films with low moisture permeability include polyolefin resins such as chain polyolefin resins, cyclic polyolefin resins (such as norbornene resins); (meth) acrylic resins such as methyl methacrylate resins Can be mentioned.

(2) Step of storing the polarizing plate A In this step, the polarizing plate A has a polarizing plate moisture content S1 after storing for one week in an environment where the polarizing plate moisture content S1 is 23 ° C. and a relative humidity of 55%. Stored in a low environment. In addition, the storage here includes the case where the polarizing plate A is transported.

  As described above, the polarizing plate A has a wavy defect with a height exceeding 3 mm on either side under the storage condition of 23 ° C. relative humidity 55% for one week, or three or more on either side. Although it is a polarizing plate that causes undulation defects, according to the storage method according to this process, while maintaining a state substantially free of undulation defects, or to the extent that problems of mixing of bubbles and the accompanying visibility degradation do not occur. It is possible to store the polarizing plate while suppressing the undulation defect, that is, in a state where no undulation defect having a height exceeding 3 mm is generated on any side and no more than 3 undulation defects are generated on any side. it can.

The polarizing plate moisture content is determined by the following drying test. That is, a 200 mm × 300 mm sample is cut out from the polarizing plate to be measured, and a drying test is performed on the sample in an oven set at 105 ° C. for 2 hours. When the weight of the sample before the drying test is W0 and the weight of the sample after the drying test is W1, the moisture content (%) of the polarizing plate is expressed by the following formula:
Polarizer moisture content (%) = 100 × {(W0−W1) / W0}
Defined by

  The polarizing plate water content S1 of the polarizing plate A after storage is 0.9 from the polarizing plate water content S0 when stored for one week in an environment of 23 ° C. and 55% relative humidity from the viewpoint of effectively suppressing wavy defects. It is preferable that it is 2 times or less (S1 ≦ 0.9S0), more preferably 0.85 times or less (S1 ≦ 0.85S0). In general, the polarizing plate moisture content S1 is 0.5 times or more (S1 ≧ 0.5S0) of the polarizing plate moisture content S0.

  As a specific method for storing in an environment where the polarizing plate moisture content S1 is lower than the polarizing plate moisture content S0 when stored at 23 ° C. and 55% relative humidity for 1 week, the polarizing plate A is low. A method of storing under humidity conditions is preferred. As a method for storing under low humidity conditions, a sealable film package having a waterproof (moisture-proof) and gas barrier property is used as a sealed container, and the polarizing plate A is sealed and sealed, or a sealable plastic is used. A method of sealing and packing the polarizing plate A using a container made of metal or a metal container as a sealed container can be exemplified.

  In addition, from the viewpoint of effectively suppressing wavy defects, this step preferably includes a step of storing the polarizing plate A in an environment with a relative humidity of 30 to 50%, and the internal relative humidity is set to 30 to 50%. More preferably, the process includes storing the polarizing plate A in the sealed container as described above, and includes the process of storing the polarizing plate A in the sealed container as described above in which the internal relative humidity is 35 to 45%. More preferably. When stored in an environment with a relative humidity of less than 30%, the height of undulation defects tends to increase. In addition, when stored in an environment where the relative humidity exceeds 50%, the number of wavy defects tends to increase.

  A suitable method for setting the relative humidity in the sealed container within the above range (decreasing the relative humidity in the sealed container) is to seal a dehumidifier such as a low-humidity inert gas (nitrogen, air, etc.) or a desiccant. Put it in a container. When an inert gas is used, the polarizing plate A may be sealed and packaged in a state where the inert gas is introduced into the sealed container and replaced with the gas. In the case of using a desiccant, the desiccant may be placed in a sealed container and hermetically sealed with the polarizing plate A.

  As the low-humidity air, dry air, for example, instrument air compressed by a compressor (the relative humidity is usually about 40% or less) can be used. As the desiccant, various porous materials such as silica gel (silica gel A type, silica gel B type, etc.), molecular sieve, activated carbon and the like can be used.

The present invention also relates to a method of manufacturing a polarizing plate including a step of storing the above polarizing plate A in the above environment. The manufacturing method of the polarizing plate includes the following steps:
(1 ′) A polarizing plate comprising a polarizer and at least one protective film laminated thereon, and when stored for one week in an environment of 23 ° C. and a relative humidity of 55%, the height at any side A step of preparing a polarizing plate A in which a waviness defect exceeding 3 mm occurs or three or more wavy defects are generated on either side, and (2 ′) a polarizing plate moisture content after storage is 23 ° C. relative humidity A step of storing the polarizing plate A in an environment where the moisture content of the polarizing plate is lower than that of the polarizing plate when stored for one week in a 55% environment;
including.

  For the details of the steps (1 ') and (2'), the above description of the steps (1) and (2) is cited. According to the manufacturing method of the polarizing plate, it is possible to provide a polarizing plate in which the undulating defect is suppressed to such an extent that the undulating defect is not substantially caused, or the above-mentioned bubble mixing and the problem of the visibility deterioration associated therewith are not caused. Can do.

<Method for eliminating or reducing undulation defects>
The method for eliminating or reducing undulation defects according to the present invention includes the following steps:
(I) A polarizing plate comprising a polarizer and at least one protective film laminated thereon, and has a wavy defect with a height exceeding 3 mm on any side, or three on any side A step of preparing a polarizing plate B having the above undulating defects, and (II) a step of storing the polarizing plate B in an environment where the polarizing plate moisture content after storage is lower than the polarizing plate moisture content before storage,
including.

  The polarizing plate B to be used in the method for eliminating or reducing the undulating defects according to the present invention is a polarizing plate in which the undulating defects are accompanied by the problem of mixing of bubbles as described above and the accompanying visibility reduction. Is a polarizing plate having a wavy defect with a height exceeding 3 mm on any side, or having three or more wavy defects on any side. The meaning and measurement method of the height and number of undulating defects are the same as described above.

  The shape of the polarizing plate B is not particularly limited, but is preferably a rectangular (typically rectangular) polarizing plate sheet having a long side of 700 mm or more and a short side of 400 mm or more. In a polarizing plate having a smaller size, wavy defects are generally less likely to be a problem. The polarizing plate B that is a single wafer is, for example, a polarizing plate in which undulating defects have occurred in the process of cutting and storing the polarizing plate manufactured as a long body and then storing and transporting it under some conditions. it can. For the layer structure of the polarizing plate B, the description of the polarizing plate A is cited. In this specification, “preparing polarizing plate B” includes obtaining (manufacturing) polarizing plate B.

  According to the step (II), the polarizing plate B is stored in an environment in which the polarizing plate moisture content T1 after storage is lower than the polarizing plate moisture content T0 before storage, thereby substantially eliminating the wavy defect of the polarizing plate B. The undulation defect can be suppressed to such an extent that it can be eliminated, or the problem of mixing of bubbles and the accompanying decrease in visibility does not occur. That is, it is possible to obtain a polarizing plate that does not have a wavy defect whose height exceeds 3 mm on any side and does not have three or more wavy defects on any side. In addition, the storage here also includes the case where the polarizing plate B is transported. The method for determining the moisture content of the polarizing plate is as described above.

  The polarizing plate moisture content T1 of the polarizing plate B after storage is 0.9 times or less (T1 ≦ 0.9T0) of the polarizing plate moisture content T0 before storage from the viewpoint of effectively eliminating or reducing the wavy defect. It is preferably 0.85 times or less (T1 ≦ 0.85T0). In general, the polarizing plate moisture content T1 is not less than 0.5 times the polarizing plate moisture content T0 (T1 ≧ 0.5T0).

  A specific method for storing in an environment where the polarizing plate moisture content T1 after storage is lower than the polarizing plate moisture content T0 before storage is as follows. It can be the same as the specific method for storing the polarizing plate A in an environment where the polarizing plate moisture content S0 is lower than that when the polarizing plate is stored for one week.

  From the viewpoint of effectively eliminating or reducing undulation defects, the step (II) preferably includes a step of storing the polarizing plate B in an environment with a relative humidity of 30 to 50%, and the internal relative humidity is preferably set to 30 to 50. It is more preferable to include a step of storing the polarizing plate B in a sealed container having a% content, and it is further preferable to include a step of storing the polarizing plate B in a sealed container having an internal relative humidity of 35 to 45%. When stored in an environment with a relative humidity of less than 30%, the height of undulation defects tends to increase. In addition, when stored in an environment where the relative humidity exceeds 50%, the number of wavy defects tends to increase. For a specific method of setting the relative humidity in the sealed container within the above range (decreasing the relative humidity in the sealed container), the description of the method for storing the polarizing plate A is cited.

The present invention also relates to a method of manufacturing a polarizing plate including a step of storing the above polarizing plate B in the above environment. The manufacturing method of the polarizing plate includes the following steps:
(I ′) A polarizing plate comprising a polarizer and at least one protective film laminated thereon, and has a wavy defect with a height exceeding 3 mm on any side, or 3 on any side A step of preparing a polarizing plate B having at least one wavy defect, and (II ′) a step of storing the polarizing plate B in an environment where the polarizing plate moisture content after storage is lower than the polarizing plate moisture content before storage,
including.

  For the details of the steps (I ′) and (II ′), the above description of the steps (I) and (II) is cited. According to the manufacturing method of the polarizing plate, it is possible to provide a polarizing plate in which the undulating defect is suppressed to such an extent that the undulating defect is not substantially caused, or the above-mentioned bubble mixing and the problem of the visibility deterioration associated therewith are not caused. Can do.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further more concretely, this invention is not limited by these examples.

<Experiment 1>
[1] Production of Polarizing Plate A long polarizing plate having the configuration shown in FIG. 2 was prepared. This polarizing plate has a layer structure of a protective film 60 having a thickness of 75 μm (consisting of a (meth) acrylic pressure-sensitive adhesive layer and a polyethylene terephthalate film) / first protective film 20 having a thickness of 80 μm ((meth) acrylic resin film) / Polarizer 10 having a thickness of 23 μm (polyvinyl alcohol film on which iodine is adsorbed and oriented) / second protective film 30 having a thickness of 50 μm (a retardation film made of a cyclic polyolefin resin) / adhesive layer 40 having a thickness of 25 μm ((meta)) (Acrylic pressure-sensitive adhesive layer) / separate film 50 (polyethylene terephthalate film) having a thickness of 38 μm. This long polarizing plate was cut into a rectangle of 1220 mm × 690 mm to obtain a single-wafer polarizing plate A.

[2] Storage of Polarizing Plate A With respect to the single-piece polarizing plate A obtained above, the storage step was performed under the following four conditions of Reference Example 1, Comparative Example 1 and Examples 1-2. The following four types of storage steps were carried out immediately after cutting out the single-piece polarizing plate A.

(Reference Example 1)
The 200 polarizing plates A were stored for 7 days in an environment of 23 ° C. and 55% relative humidity without being accommodated in a container.

(Comparative Example 1)
200 polarizing plates A were put in a plastic container having a rubber packing at the heel of the opening and impermeable to moisture, sealed, and stored in an environment of 23 ° C. for 10 days. The relative humidity at the beginning of storage was 55%, and the relative humidity after storage for 10 days was 53%. For the measurement of the temperature and humidity in the container, “Ondori” (Tr-72Ui manufactured by T & D Corporation) was used (the same applies hereinafter).

Example 1
In the same plastic container used in Comparative Example 1, 200 polarizing plates A are placed, 10 g of silica gel A type (CP series manufactured by Fuji Gel Sangyo Co., Ltd.) is placed, sealed, and sealed in an environment of 23 ° C. Stored for days. The relative humidity at the beginning of storage was 55%, and the relative humidity after storage for 10 days was 42%.

(Example 2)
After putting 200 polarizing plates A into the same plastic container as used in Comparative Example 1, instrumented air with a relative humidity of 23% at 23 ° C. was introduced into the container, sealed and sealed, and in an environment at 23 ° C. And stored for 10 days. The relative humidity at the beginning of storage was 45%, and the relative humidity after storage for 10 days was 47%.

[3] Evaluation of polarizing plate after storage The polarizing plate after the storage step was evaluated for the following items. The results are shown in Table 1.

(Polarizer moisture content)
One sheet was randomly extracted from the 200 polarizing plates after the storage step, the above-mentioned drying test was performed on this polarizing plate, and the polarizing plate moisture content was calculated according to the above-described definition formula. In addition, the polarizing plate moisture content of the polarizing plate A before storage (immediately after cutting) was 1.8%.

(Number and height of undulating defects)
One of the 200 polarizing plates after the storage step is randomly extracted, placed on a flat table with the protective film 60 facing downward, and the number of wavy defects on each side of the polarizing plate (as described above). In addition, the height is limited to the undulating defect whose height is 0.5 mm or more from the plane table.), And the height of the undulating defect from the plane table was measured. Table 1 shows the number of undulation defects on the side having the most undulation defects and the height of the highest undulation defect among all the undulation defects.

(With or without air bubbles)
One of the 200 polarizing plates after the storage process is randomly extracted, and this polarizing plate is removed through the pressure-sensitive adhesive layer of the polarizing plate using a large precision bonding machine (Clim Products, HAL-1485). It bonded to alkali glass (Corning company make, Eagle XG), and the presence or absence of the bubble in the peripheral part of the bonding interface of an adhesive layer and an alkali free glass was confirmed visually.

<Experiment 2>
[1] Storage of Polarizing Plate A The single-piece polarizing plate A produced in Experiment 1 was subjected to a storage process under the following four conditions of Comparative Example 2 and Examples 3-5. The following four types of storage steps were carried out immediately after cutting out the single-piece polarizing plate A.

(Comparative Example 2)
Thirty polarizing plates A are placed in a retort bag (Kite Chemical Industries Co., Ltd.) in which a thin aluminum film is used as a moisture-proof layer and a plurality of gas barrier resin films are laminated. , Sealed and stored in an environment of 23 ° C. for 10 days. The relative humidity at the beginning of storage was 55%, and the relative humidity after storage for 10 days was 50%.

(Example 3)
After 30 polarizing plates were put in the same retort bag used in Comparative Example 2, instrumented air with a relative humidity of 23% at 23 ° C. was introduced into the container, sealed, sealed, and sealed in an environment at 23 ° C. Stored for days. The relative humidity at the beginning of storage was 36%, and the relative humidity after storage for 10 days was 39%.

Example 4
After putting 30 polarizing plates into the same retort bag as used in Comparative Example 2, nitrogen gas at 23 ° C. was introduced into the container, filled and sealed, and stored in an environment at 23 ° C. for 10 days. The relative humidity at the beginning of storage was 35%, and the relative humidity after storage for 10 days was 36%.

(Example 5)
In the same retort bag as used in Comparative Example 2, 30 polarizing plates A were placed and 10 g of silica gel A type (CP series manufactured by Fuji Gel Sangyo Co., Ltd.) was placed and sealed. Stored for days. The relative humidity at the beginning of storage was 55%, and the relative humidity after storage for 10 days was 35%.

[2] Evaluation of polarizing plate after storage The polarizing plate after the storage step was evaluated in the same manner as in Experiment 1 for the water content of the polarizing plate, the number and height of wavy defects, and the presence or absence of bubbles. The results are shown in Table 2. Table 2 also shows the storage conditions and evaluation results of Reference Example 1 for comparison.

<Experiment 3>
[1] Storage of polarizing plate B (elimination or reduction of wavy defects)
About the polarizing plate (polarizing plate B) after the storage process obtained in Reference Example 1, the storage process was performed under the two conditions of Examples 6 to 7 below to eliminate or reduce undulation defects.

(Example 6)
After putting 200 polarizing plates B into the same plastic container as used in Comparative Example 1, instrumented air having a relative humidity of 23% at 23 ° C. was introduced into the container, sealed, and sealed in an environment at 23 ° C. And stored for 5 days. The relative humidity at the beginning of storage was 44% (the relative humidity was adjusted by the introduction time of instrument air). The relative humidity after storage for 5 days was 45%.

(Example 7)
After putting 200 polarizing plates B into the same plastic container as used in Comparative Example 1, instrumented air having a relative humidity of 23% at 23 ° C. was introduced into the container, sealed, and sealed in an environment at 23 ° C. And stored for 5 days. The relative humidity at the beginning of storage was 38% (the relative humidity was adjusted by the introduction time of instrument air). The relative humidity after storage for 5 days was 40%.

[2] Evaluation of polarizing plate after storage The polarizing plate after the storage step was evaluated in the same manner as in Experiment 1 for the water content of the polarizing plate, the number and height of wavy defects, and the presence or absence of bubbles. The results are shown in Table 3. Table 3 also shows the storage conditions and evaluation results of Reference Example 1 for comparison.

  DESCRIPTION OF SYMBOLS 1 Polarizing plate, 10 Polarizer, 20 1st protective film, 30 2nd protective film, 40 Adhesive layer, 50 Separate film, 60 Protective film.

Claims (9)

A polarizing plate comprising a polarizer and at least one protective film laminated thereon, the height of which exceeds 3 mm on either side when stored for one week in an environment at 23 ° C. and 55% relative humidity Preparing a polarizing plate that causes undulation defects or three or more undulation defects on either side;
A step of storing the polarizing plate in an environment where the polarizing plate moisture content after storage is lower than the polarizing plate moisture content when stored for one week in an environment of 23 ° C. and 55% relative humidity;
A method for storing a polarizing plate, comprising: A polarizing plate comprising a polarizer and at least one protective film laminated thereon, and having a undulation defect whose height exceeds 3 mm on any side, or three or more undulations on any side Preparing a polarizing plate having defects;
Storing the polarizing plate in an environment where the polarizing plate moisture after storage is lower than the polarizing plate moisture before storage;
The method of eliminating or reducing the wavy defect which the polarizing plate contains. A polarizing plate comprising a polarizer and at least one protective film laminated thereon, the height of which exceeds 3 mm on either side when stored for one week in an environment at 23 ° C. and 55% relative humidity Preparing a polarizing plate that causes undulation defects or three or more undulation defects on either side;
A step of storing the polarizing plate in an environment where the polarizing plate moisture content after storage is lower than the polarizing plate moisture content when stored for one week in an environment of 23 ° C. and 55% relative humidity;
The manufacturing method of a polarizing plate containing. A polarizing plate comprising a polarizer and at least one protective film laminated thereon, and having a undulation defect whose height exceeds 3 mm on any side, or three or more undulations on any side Preparing a polarizing plate having defects;
Storing the polarizing plate in an environment where the polarizing plate moisture after storage is lower than the polarizing plate moisture before storage;
The manufacturing method of a polarizing plate containing.   The method according to any one of claims 1 to 4, wherein the storing step includes a step of storing the polarizing plate in an environment having a relative humidity of 30 to 50%.   The method according to claim 1, wherein the polarizing plate is stored in a sealed container in the storing step.   The method according to claim 1, wherein the polarizing plate is stored in a sealed container containing a dehumidifying agent in the storing step.   The method according to claim 1, wherein the polarizing plate prepared in the preparing step has a rectangular shape with a long side of 700 mm or more and a short side of 400 mm or more.   The method according to any one of claims 1 to 8, wherein at least one of the protective films is a thermoplastic resin film selected from the group consisting of a polyolefin resin film and a (meth) acrylic resin film.