KR20150089954A - Method of storing a polarizing plate, method of removing or reducing wavy defects in the polarizing plate, and method of menufacturing the polarizing plate - Google Patents

Abstract

Provided are a method of storing a polarizing plate and a method of manufacturing a polarizing plate. The method for storing a polarizing plate comprises the processes of: preparing a polarizing plate, as polarizing plate including a polarizer and a protective film stacked on the polarizer, which produces a wavy defect whose height exceeds 3 mm on any edge, or produces three or more wavy defects on any edge when the polarizing plate is stored at 23°C under a relative humidity of 55% for one week; and storing the polarizing plate in an environment where a moisture regain of the polarizing plate after the storage becomes lower than the moisture regain measured when the polarizing plate is stored at 23°C under a relative humidity of 55% for one week.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate, a polarizing plate, a polarizing plate, a polarizing plate, a polarizing plate, and a method of manufacturing the polarizing plate.

The present invention relates to a method for storing a polarizing plate suitably used in an image display apparatus such as a liquid crystal display apparatus, a method for eliminating or reducing a wave defect in a polarizing plate, and a method for producing a polarizing plate.

A liquid crystal display device includes a liquid crystal panel including a liquid crystal cell and a polarizing plate bonded to the front and back surfaces thereof and a case for accommodating the liquid crystal panel and a frame for covering and covering the periphery of the liquid crystal panel and the front polarizing plate Is widely used. This frame is required to have a narrower width 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 surfaces of a polarizer through an adhesive layer (for example, Japanese Patent Application Laid-Open No. 2004-245925). Polarizers and protective films are usually made of different materials, and there are cases where they cause deformation (also called wave curl) in which the polarizing plate wobbles in a wave form during storage after production, for the reason thereof. In the present specification, the apparent problem that such a polarizing plate is deformed into a wave shape is referred to as " wave defect ".

Wavy defects tend to be conspicuous in the height and / or number of waves generated, especially when the polarizer size is large. When a wavy defect is generated in the polarizing plate, for example, in the case of applying to a liquid crystal display device, for example, when the polarizing plate and the liquid crystal cell are bonded to each other through the pressure-sensitive adhesive layer, the bonding interface between the pressure- Air bubbles are likely to be mixed in the vicinity thereof. If this bubble is generated in the image display region of the liquid crystal panel, it may become a bright spot at the time of lighting, and the visibility may be lowered. Therefore, in a polarizing plate which is applied to a liquid crystal display using a polarizing plate, particularly a case with a narrow frame width as described above, and a region closer to the periphery of the polarizing plate is used for the image display region, Or it is required that the wavy defects are sufficiently reduced to such an extent as not to cause the problem of bubble entrainment or deterioration of visibility accompanied with the above-mentioned bubble formation.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method of storing a polarizing plate capable of suppressing a wave defect to such an extent that it is possible to maintain a state without substantial wave defects or to avoid the problem of the above- . Another object of the present invention is to provide a method capable of substantially eliminating the wavy defect of the polarizing plate which has caused wavy defects or suppressing the wavy defect to such an extent as not to cause the problem. It is still another object of the present invention to provide a method of manufacturing a polarizing plate having substantially no wave defects or suppressing wave defects to such an extent as not causing the problems.

The present invention provides a method for storing a polarizing plate described below, a method for eliminating or reducing a wavy defect in a polarizing plate, and a method for producing a polarizing plate.

[1] A polarizing plate comprising a polarizer and at least one protective film laminated on the polarizer, characterized in that when the polarizing plate is stored for one week under the environment of a relative humidity of 55% at 23 캜, a wave defect having a height exceeding 3 mm , Or a polarizing plate which generates three or more wavy defects on either side,

Storing the polarizing plate in an environment in which the moisture content of the polarizing plate after storage is lower than the moisture content of the polarizing plate when stored for one week under an environment of 23 DEG C and a relative humidity of 55%.

[2] A polarizing plate comprising a polarizer and at least one protective film laminated thereon, wherein a polarizing plate having a wavy defect having a height of more than 3 mm at either side or having at least three wavy defects at either side is prepared ;

And storing the polarizing plate under an environment in which the moisture content of the polarizing plate after storage is lower than the moisture content of the polarizing plate before storage.

[3] A polarizing plate comprising a polarizer and at least one protective film laminated on the polarizer, characterized in that when the polarizing plate is stored for one week under the environment of a relative humidity of 55% at 23 캜, a wave defect having a height exceeding 3 mm , Or a polarizing plate which generates three or more wavy defects on either side,

And storing the polarizing plate under an environment in which the moisture content of the polarizing plate after storage is lower than the moisture content of the polarizing plate when stored for one week under an environment of 23 占 폚 and a relative humidity of 55%.

[4] A polarizing plate comprising a polarizer and at least one protective film laminated thereon, wherein a polarizing plate having a wavy defect having a height of more than 3 mm at either side or having at least three wavy defects at either side is prepared ;

And storing the polarizing plate under an environment in which the moisture content of the polarizing plate after storage is lower than the moisture content of the polarizing plate before storage.

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

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

[7] The method according to any one of [1] to [5], wherein the polarizing plate in the step of storing 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] The method according to any one of [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.

According to the present invention, it is possible to provide a polarizing plate which is substantially suppressed to such an extent that it does not have a wavy defect substantially at the time of bonding with another member such as a liquid crystal cell, or that the wavy defect does not cause the problem of bubble entrainment and deterioration of visibility accompanied by the above- Can be provided.

1 is a side view showing an example of a polarizing plate having a wavy defect.
2 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate provided in the storage method of the present invention, a method of eliminating or reducing wavy defects, and a method of manufacturing a polarizing plate.

≪ Polarizing plate storage method >

A method for storing a polarizing plate according to the present invention comprises the steps of:

(1) A polarizing plate comprising a polarizer and at least one protective film laminated on the polarizer, characterized in that when a sheet is stored for one week under an environment of 55% relative humidity at 23 DEG C, a wave defect having a height exceeding 3 mm , Or a polarizing plate A which generates three or more wavy defects on either side, and

(2) a step of storing the polarizing plate A under an environment in which the moisture content of the polarizing plate after storage is lower than the moisture content of the polarizing plate when stored for one week under the environment of 23 ° C and 55% relative humidity. Hereinafter, each process will be described.

(1) Step of preparing polarizing plate A

The polarizing plate A provided in the method for storing a polarizing plate according to the present invention is a polarizing plate which is liable to cause a wave defect accompanied by the above-described bubble entrainment and accompanying deterioration of visibility under ordinary storage conditions. Specifically, Referring to FIG. 1, when stored for one week under an environment of 23% relative humidity at 55%, a wave defect having a height exceeding 3 mm occurs at any side, or three or more wave defects occur at any side Polarizer. Such a polarizing plate having a wave defect is liable to cause the above problem. 1 is a side view showing an example of a polarizing plate having a wavy defect, and shows a side where a wave defect is generated in the polarizing plate. In the example of Fig. 1, the sides have five wavy defects (wavy deformations W, X and Z in Fig. 1), one of which is a wavy defect having a height of more than 3 mm Wave type deformation X).

The height of the wave defect is the height from the plane of the polarizer to the top of the wave defect when the polarizer is placed on the flat base. The height is measured at the sides (end portions) of the polarizing plate. In addition, the number of wavy defects is the number of wavy defects that are substantially recognized as wavy defects. Specifically, the number of wavy defects is 0.5 mm or more in height when the polarizing plate is placed on a flat base. Therefore, the wavy deformation whose height is less than 0.5 mm from the plane as in Y shown in Fig. 1 is not counted as a wavy defect. The wavy strain Z shown in Fig. 1 is 0.5 mm in height, counted as a wavy defect. The number of wavy defects is also measured at the sides (end portions) of the polarizing plate. On the other hand, like the K shown in Fig. 1, the ends (edges) of the sides (end portions) of the polarizing plate are not counted as a wave defect even if they float from the plane.

The shape of the polarizing plate A is not particularly limited, but it is preferable that the polarizing plate A is a rectangular (typically rectangular) sheet having a long side of 700 mm or more and a short side of 400 mm or more. For polarizers smaller than this, wavy defects are generally not a problem. The sheet polarizer A can be obtained, for example, by cutting a polarizer produced as a long sheet. In the present specification, "preparing polarizing plate A" also includes obtaining (making) polarizing plate A.

The layer structure of the polarizing plate A is not particularly limited as long as it has a polarizer and at least one protective film laminated thereon. However, in a polarizing plate for liquid crystal display, for example, before storage for practical use, The polarizing plate generally has a pressure-sensitive adhesive layer for bonding to the liquid crystal cell. Further, a polarizing plate for protecting the surface (outer surface) of the pressure-sensitive adhesive layer and a separator film for protecting the surface In general, it is preferable that the polarizing plate A has a pressure-sensitive adhesive layer, a separate film and a protective film in addition to the polarizer and the protective film in order to provide a protective film (surface protective film).

An example of the layer structure of the polarizing plate A is shown in Fig. The polarizing plate 1 shown in Fig. 2 comprises a polarizer 10; A first protective film (20) bonded to one surface of the polarizer (10); A second protective film (30) 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 protection film 60 laminated on the outer surface of the first protective film 20.

The polarizer 10 is an optical film that absorbs linearly polarized light having a vibration plane parallel to the optical axis and transmits linearly polarized light having a vibration plane perpendicular to the optical axis, and is, for example, uniaxially stretched, May be a polyvinyl alcohol-based resin film with adsorption orientation. As the dichroic dye, iodine or a dichroic organic dye is used. The polyvinyl alcohol resin constituting the polarizer 10 may be a polyvinyl alcohol which is a saponified polyvinyl acetate, a saponification product of a copolymer of vinyl acetate and another monomer copolymerizable therewith (for example, ethylene or an unsaturated carboxylic acid) Or a vinyl alcohol-based copolymer. The thickness of the polarizer 10 is usually about 5 to 40 mu m.

The polarizer 10 includes a step of uniaxially stretching a polyvinyl alcohol resin film, a step of dying a polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye, a step of dying the dichroic dye with a polyvinyl alcohol Based resin film with an aqueous solution of boric acid, and a step of washing with water after treatment with an aqueous solution of boric acid. The dyeing of the dichroic dye can be performed by immersing the film in an aqueous solution containing a dichroic dye, and the treatment with an aqueous solution of boric acid can be performed by immersing the film in an aqueous solution of boric acid.

The uniaxial stretching of the polyvinyl alcohol resin film can be performed before, simultaneously with, or after dyeing the dichroic dye. In the case where uniaxial stretching is carried out after dyeing, this uniaxial stretching may be carried out before the boric acid treatment or during the boric acid treatment. In addition, uniaxial stretching may be performed in these plural stages.

The first and second protective films 20 and 30 may be thermoplastic resin films having translucency (preferably optically transparent). Specific examples of the thermoplastic resin include a polyolefin-based resin such as a chain-like polyolefin-based resin, a cyclic polyolefin-based resin (norbornene-based resin and the like); Polyester-based resins such as polyethylene terephthalate; (Meth) acrylic resins such as methyl methacrylate resins; Cellulosic resins such as cellulose triacetate and cellulose diacetate; Polycarbonate resin; Polyvinyl alcohol-based resin; Polyvinyl acetate resin; Polyarylate resins; Polystyrene type resin; Polyether sulfone type resin; Polysulfone resins; Polyamide based resin; Polyimide resin; And mixtures and copolymers thereof. In the present specification, the term "(meth) acrylic resin" refers to at least one kind selected from the group consisting of an acrylic resin and a methacrylic resin. The same applies to the term to which other "(meth)" is added. 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 first protective film 20 and the second protective film 30 may be composed of the same kind of thermoplastic resin or may be composed of different kinds of thermoplastic resins. The thickness of the first and second protective films 20 and 30 is, for example, about 5 to 200 mu m, preferably 10 to 150 mu m, and more preferably 20 to 100 mu m.

The pressure-sensitive adhesive layer (40) is a layer for bonding a polarizing plate to another member such as a liquid crystal cell. Examples of the pressure sensitive adhesive constituting the pressure sensitive adhesive layer 40 include (meth) acrylic pressure sensitive adhesives, urethane pressure sensitive adhesives, silicone pressure sensitive adhesives, polyester pressure sensitive adhesives, polyamide pressure sensitive adhesives, polyether pressure sensitive adhesives, fluorinated pressure sensitive adhesives and rubber pressure sensitive adhesives . Among them, 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 占 퐉.

The separate film 50 and the protective film 60 are 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 or transported or inspected. The separate film 50 for protecting the pressure-sensitive adhesive layer 40 is peeled off immediately before the polarizing plate 1 is provided for practical use (for example, bonded to another member such as a liquid crystal cell). Further, the protective film 60 is normally peeled off from the pressure-sensitive adhesive layer after the polarizing plate 1 is provided for 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 having one side subjected to releasing treatment, and the release-treated side thereof is bonded to the pressure-sensitive adhesive layer 40. Further, the protective film 60 is usually constituted by providing a pressure-sensitive adhesive layer on one surface of a thermoplastic resin film. The thermoplastic resin constituting the separate film 50 and the protective film 60 can be made of, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate . With regard to the pressure-sensitive adhesive layer of the protection film 60, the technique relating to the pressure-sensitive adhesive layer 40 described above is cited.

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

[a] Configuration in which any one or more of the pressure-sensitive adhesive layer (40), the separate film (50) and the protection film (60)

[b] Configuration in which either the first protective film 20 or the second protective film 30 is omitted,

[c] Configuration using an optical compensation film such as a retardation film as the second protective film 30,

[d] Configuration in which, in addition to the first protective film (20) and the second protective film (30), an optical compensation film such as a retardation film is provided.

An example of the above-mentioned [b] is a configuration in which the second protective film 30 is omitted, and a suitable embodiment thereof is a method in which the pressure sensitive adhesive layer 40 is directly applied to the surface of the polarizer 10 opposite to the protective film 60 And the layer structure of the protective film 60 / the first protective film 20 / the polarizer 10 / the pressure-sensitive adhesive layer 40 / the separate film 50 is laminated.

A suitable specific example of the above-mentioned [c] is that the protective film 60 / the first protective film 20 / the polarizer 10 / the retardation film (second protective film 30) / the pressure sensitive adhesive layer 40 / 50). A suitable example of the above [d] is a protective film 60 / a first protective film 20 / a polarizer 10 / a second protective film 30 / a retardation film / a pressure sensitive adhesive layer 40 / a separate film 50 ) Layer.

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

The polarizer 10 and the first protective film 20 and the second protective film 30 (including the case of a retardation film) are laminated with an adhesive or a pressure sensitive adhesive (with respect to the pressure sensitive adhesive, Can be cited). 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 may be, for example, a polyvinyl alcohol-based resin or a urethane resin. The active energy ray-curable adhesive may be, for example, a curable composition comprising 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 may be an adhesive of a solventless form, but may also include an organic solvent (a solvent other than water). When the adhesive agent of the solventless form is used, a drying treatment for removing the solvent becomes unnecessary. When an active energy ray-curable adhesive is used, the adhesive layer is cured by irradiating active energy rays such as visible light, ultraviolet rays, X-rays, and electron rays, preferably ultraviolet rays, after bonding the film through an adhesive.

In the case of using an aqueous adhesive, the film laminate bonded through the adhesive is usually subjected to a drying treatment to remove moisture from the adhesive layer. In this case, when the film to be bonded to the polarizer 10 is a thermoplastic resin film having low moisture permeability, there is a case in which the drying time is prolonged and the productivity is lowered, the water in the aqueous adhesive can not be sufficiently dried, have. In view of this, the active energy ray-curable adhesive is advantageous in that even when a thermoplastic resin film having low moisture permeability is bonded, the above-described problem does not occur.

When a thermoplastic resin film having low moisture permeability is bonded to the polarizer 10, the difference in moisture content between the polarizer 10 and the polarizer 10 tends to increase, and the wave defects of the polarizer 10 tend to increase. Therefore, the present invention is particularly effective when a thermoplastic resin film having low moisture permeability is used as the first protective film 20 and / or the second protective film 30 (including the case of a retardation film). Specific examples of the thermoplastic resin film having low moisture permeability include polyolefin-based resins such as a chain-like polyolefin-based resin and a cyclic polyolefin-based resin (norbornene-based resin and the like); And (meth) acrylic resins such as methyl methacrylate resins.

(2) Step of storing polarizing plate A

In this step, the polarizing plate A is stored under an environment in which the polarizing plate moisture ratio S 1 after storage is lower than the polarizing plate moisture ratio S 0 when stored for one week under an environment of 23 ° C and a relative humidity of 55%. The term "storage" as used herein includes cases where the polarizing plate A is carried.

As described above, in the polarizing plate A, at a temperature of 23 DEG C and a relative humidity of 55% for one week, a wavy defect having a height exceeding 3 mm occurs at any side or a wavy defect occurs at three sides or more on any side According to the storage method according to the present process, while suppressing the wave defect so as not to cause a problem of substantially no wavy defect or a problem of a decrease in visibility due to the incorporation of bubbles, that is, The polarizing plate can be kept in a state in which a wave defect having a height of more than 3 mm is not generated and no wave defects are generated in any of three sides.

The moisture content of the polarizing plate is determined by the following drying test. That is, a sample of 200 mm x 300 mm is cut out from the polarizing plate of the measurement object, and a drying test is performed in which the sample is dried in an oven set at 105 DEG 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 polarizer is represented by the following formula:

Polarizer water content (%) = 100 x {(W0-W1) / W0}

.

From the viewpoint of effectively suppressing wavy defects, it is preferable that the moisture content ratio S1 of the polarizing plate A after storage is 0.9 times or less (S1? 0.9S0) of the moisture content S0 of the polarizing plate when stored for one week under an environment of 23% relative humidity at 55% , And more preferably 0.85 times or less (S1? 0.85S0). Normally, the moisture content S 1 of the polarizer is 0.5 times or more (S 1? 0.5S0) of the moisture content S 0 of the polarizer.

As a specific method for storing the polarizing plate A in an environment in which the moisture content S1 of the polarizing plate is lower than the moisture content S0 of the polarizing plate when stored for 1 week under an environment of 23 deg. C and a relative humidity of 55%, the method of storing the polarizing plate A under low humidity conditions is suitable. As a method of storing under low humidity conditions, a method of sealing a polarizing plate A by using a sealable film package having a waterproof property (moisture-proofing property) and a gas barrier property as a sealing container, A container or a metal container is used as a sealing container, and the polarizing plate A is sealed and packed.

From the viewpoint of effectively suppressing the wavy defect, the present step preferably includes a step of storing the polarizing plate A under an environment of a relative humidity of 30 to 50%, and it is preferable that the polarizing plate A is kept at a relative humidity of 30 to 50% It is more preferable to include a step of storing the polarizing plate A in the same sealed container and more preferably a step of storing the polarizing plate A in the sealed container as described above in which the relative humidity inside is set to 35 to 45% Do. When stored under an environment of less than 30% relative humidity, the height of the wave defect tends to increase. Further, when stored under an environment where the relative humidity exceeds 50%, the number of wavy defects tends to increase.

A suitable method of setting the relative humidity in the sealed container to the aforementioned range (lowering the relative humidity in the sealed container) is to put a dehumidifying agent such as an inert gas (nitrogen, air, etc.) of low humidity or a desiccant into the sealed container. In the case of using an inert gas, an inert gas is introduced into the sealed container and the polarizing plate A is sealingly packed in the state of being substituted with the gas. In the case of using a desiccant, a desiccant may be placed in a sealed container and sealed together with the polarizing plate A.

As the low humidity air, dry air, for example, instrument air (whose relative humidity is usually about 40% or less) compressed by a compressor can be used. As the drying agent, 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 the step of storing the above-mentioned polarizing plate A under the above-described environment. The method for producing the polarizing plate may comprise the steps of:

(1 ') polarizer and at least one protective film laminated thereon, wherein when the polarizer is stored for one week under the environment of a relative humidity of 55% at 23 DEG C, wave defects having a height of more than 3 mm Or a polarizing plate A which generates three or more wavy defects on either side, and

And a step of storing the polarizing plate A under an environment in which the moisture content of the polarizing plate after storage is lower than that of the polarizing plate when stored for one week under the environment of 23 ° C and 55% relative humidity.

Regarding the details of steps (1 ') and (2'), the techniques relating to steps (1) and (2) described above are cited. According to the method for producing a polarizing plate, it is possible to provide a polarizing plate in which a wave defect is suppressed to such a degree that it does not have a wavy defect substantially or does not cause the problems of bubble entrainment and deterioration of visibility accompanied therewith.

<Method of eliminating or reducing wavy defects>

The method for eliminating or reducing a wave defect according to the present invention comprises the following steps:

(I) A polarizing plate comprising a polarizer and at least one protective film laminated thereon, wherein the polarizing plate B having a wavy defect of more than 3 mm in height at any side or having at least three wavy defects in either side A preparation step, and

(II) storing the polarizing plate B under an environment in which the moisture content of the polarizing plate after storage is lower than the moisture content of the polarizing plate before storage.

The polarizing plate B provided in the method of eliminating or reducing the undulation of wavy lines according to the present invention is a polarizing plate which generates a wave defect accompanied by a problem of bubble entrainment and deterioration of visibility accompanied with the above-described bubbles. More specifically, Has a wavy defect of more than 3 mm, or a wavy defect of three or more wings on either side. The meaning and measurement method of height and number of wavy defects are the same as above.

The shape of the polarizing plate B is not particularly limited, but it is preferable that the polarizing plate B is a rectangular (usually rectangular) polarizing sheet having a long side of 700 mm or more and a short side of 400 mm or more. For polarizers smaller than this, wavy defects are generally not a problem. The polarizing plate B as a sheet may be a polarizing plate in which, for example, a polarizing plate produced as an elongated body is cut, and wave defects are generated in a process of storing and transporting under certain conditions. Regarding the layer constitution of the polarizing plate B, the description relating to the polarizing plate A is cited. In the present specification, "preparing polarizing plate B" also includes obtaining (producing) polarizing plate B.

According to the step (II), the polarizing plate B is kept under an environment in which the polarizing plate moisture ratio T1 after storage becomes lower than the polarizing plate moisture ratio T0 before storage, whereby the wave defects of the polarizing plate B can be substantially eliminated, It is possible to suppress wave defects to such an extent as not to cause a problem of visibility deterioration. That is, it is possible to obtain a polarizing plate which does not have a wavy defect having a height of more than 3 mm at any side, and does not have three or more wavy defects at any side. The storage also includes a case where the polarizing plate B is transported or the like. The method for obtaining the moisture content of the polarizer is as described above.

(T1? 0.9T0) of the polarizing plate moisture content T0 before storage (T1? 0.9T0) and preferably not more than 0.85 times (T1? 0.85T0) of the polarizing plate moisture content T0 before storage from the standpoint of effectively eliminating or reducing the wave defects, Is more preferable. Normally, the water content T1 of the polarizing plate is 0.5 times or more (T1? 0.5T0) of the water content T0 of the polarizing plate.

A specific method for storing the polarizing plate moisture ratio S1 after storage in an environment in which the polarizing plate moisture ratio T1 before storage is lower than the polarizing plate moisture ratio T0 before storage is that the above-described polarizing plate moisture ratio S1 is lower than the polarizing plate moisture ratio S0 when stored for one week under an environment of 23 deg. C and a relative humidity of 55% It may be the same as the specific method for storing the polarizing plate A under a losing environment.

From the viewpoint of effectively eliminating or reducing wavy defects, the step (II) preferably includes a step of storing the polarizing plate B under an environment of a relative humidity of 30 to 50%, and it is preferable that the relative humidity of the inside is set to 30 to 50% It is more preferable to include a step of storing the polarizing plate B in the sealed container, and more preferably, a step of storing the polarizing plate B in the sealed container having an internal relative humidity of 35 to 45%. When stored under an environment of less than 30% relative humidity, the height of the wave defect tends to increase. Further, when stored under an environment where the relative humidity exceeds 50%, the number of wavy defects tends to increase. With respect to a specific method of setting the relative humidity in the sealed container to the above-described range (lowering the relative humidity in the sealed container), a technique relating to a method of 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-mentioned polarizing plate B under the above-described environment. The method for producing the polarizing plate may comprise the steps of:

(I ') polarizer and at least one protective film laminated thereon, the polarizer comprising a polarizing plate B having a wavy defect having a height of more than 3 mm at any side or having at least three wavy defects at either side ; And

And the polarizing plate B is kept under an environment in which the moisture content of the polarizing plate after storage of the polarizing plate (II ') becomes lower than the moisture content of the polarizing plate before storage.

Regarding the details of steps (I ') and (II'), the techniques relating to steps (I) and (II) described above are cited. According to the method for producing a polarizing plate, it is possible to provide a polarizing plate in which a wave defect is suppressed to such a degree that it does not have a wavy defect substantially or does not cause the problems of bubble entrainment and deterioration of visibility accompanied therewith.

Yes

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

<Experiment 1>

[1] Production of polarizer

A long polarizing plate having the configuration shown in Fig. 2 was prepared. The layer structure of this polarizing plate is the same as that of the first protective film 20 ((meth) acrylic resin film (protective film)) having a thickness of 75 占 퐉 and a protective film 60 (comprising a (meth) acrylic pressure sensitive adhesive layer and a polyethylene terephthalate film) / Polarizer 10 (polyvinyl alcohol film with iodine adsorption orientation) / thickness of 23 占 퐉 / second protective film 30 (retardation film comprising cyclic polyolefin resin) 50 占 퐉 thick / pressure-sensitive adhesive with a thickness of 25 占 퐉 Layer 40 ((meth) acrylic pressure-sensitive adhesive layer) / separate film 50 (polyethylene terephthalate film) having a thickness of 38 mu m. This long polarizing plate was cut into a rectangular shape of 1220 mm x 690 mm to obtain a polarizing plate A of each green body.

[2] Storage of Polarizer A

The polarizing plate A of each sheet obtained above was stored under the four conditions of Reference Example 1, Comparative Example 1 and Examples 1 and 2 described below. The following four kinds of storing processes were carried out immediately after cutting out the polarizing plate A of each green body.

(Reference Example 1)

200 Polarizer A was not housed in a container and stored for 7 days under an environment of 23% relative humidity at 55%.

(Comparative Example 1)

200 polarizing plates A were placed in a plastic container having a rubber packing inside deep inside the opening and not allowing moisture to pass through, sealed, and stored at 23 캜 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, &quot; temperature soil &quot; (Tr-72Ui manufactured by T & D Corporation) was used.

(Example 1)

200 sheets of polarizing plates A were placed in the same plastic container as used in Comparative Example 1, and 10 g of a silica gel type A (CP series manufactured by Fuji Gel Industries Co., Ltd.) was sealed, sealed, and stored at 23 캜 for 10 days. The relative humidity at the beginning of storage was 55%, and the relative humidity after storage for 10 days was 42%.

(Example 2)

200 polarizing plates A were placed in the same plastic container as that used in Comparative Example 1, and then instrument air having a relative humidity of 30% at 23 DEG C was introduced into the container, filled, sealed, and stored at 23 DEG C 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 polarizer after storage

With respect to the following items, evaluation of the polarizing plate after the storage step was performed. The results are shown in Table 1.

(Polarizer water content)

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

(The number of wavy defects and height)

One sheet was randomly picked out from the 200 sheets of the polarizing plate after the storing process, and the polarizing plate was placed on a flat plate with the side of the protective film 60 facing downward. The number of wavy defects at each side of the polarizing plate (Only for wavy defects greater than 0.5 mm from the plane), and the height of the wavy defects from the plane was measured. Table 1 lists the number of wavy defects on the sides with the most wavy defects, the height of the highest wavy defects of all wavy defects.

(Presence of bubbles)

One sheet was randomly picked out from 200 sheets of the polarizing plate after the storing process, and this polarizing plate was coated with a non-alkali glass (Eagle XG, manufactured by Corning Incorporated) through a pressure sensitive adhesive layer of a polarizing plate using a large precision adapter (HAL- ), And the presence or absence of air bubbles at the periphery of the bonding interface between the pressure-sensitive adhesive layer and the non-alkali glass was visually confirmed.

Reference Example 1 Comparative Example 1 Example 1 Example 2 keep
Condition


Vessel - Plastic containers Desiccant - - Silica gel Instrument air Temperature (℃) 23 23 23 23 Relative humidity (%)
(After end of storage) 55 53 42 47 Duration (days) 7 10 10 10 evaluation
result

Polarizer water content (%) 1.9 1.9 1.7 1.7 wave
flaw several) 4 3 2 2 Height (nm) 3.0 3.0 1.0 2.0 Presence of bubbles U U radish radish

<Experiment 2>

[1] Storage of Polarizer A

The polarizing plate A of each green body produced in Experiment 1 was subjected to a storage step under the four conditions of Comparative Example 2 and Examples 3 to 5 described below. The following four kinds of storing processes were carried out immediately after cutting out the polarizing plate A of each green body.

(Comparative Example 2)

Thirty pieces of polarizing plates A were put into a retort bag (manufactured by KIT CHEMICAL INDUSTRIES CO., LTD.) In which a gas barrier property resin film was laminated with a multilayer of an aluminum thin film as a film layer having waterproof property and gas barrier property, , And stored at 23 캜 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)

30 polarizers were placed in the same retort pouch as used in Comparative Example 2, and then instrument air having a relative humidity of 30% at 23 DEG C was introduced into the container, filled, sealed, and stored at 23 DEG C for 10 days. The relative humidity at the beginning of storage was 36%, and the relative humidity after storage for 10 days was 39%.

(Example 4)

Thirty sheets of polarizing plates were put in the same retort pouch as used in Comparative Example 2, and then nitrogen gas at 23 DEG C was introduced into the container, filled, sealed, and stored at 23 DEG C for 10 days. The initial relative humidity at the start of storage was 35%, and the relative humidity after storage for 10 days was 36%.

(Example 5)

Thirty pieces of the polarizing plate A were placed in the same retort pouch as used in Comparative Example 2, and 10 g of a silica gel type A (CP series manufactured by Fuji Gel Industries Co., Ltd.) was sealed, and kept at 23 캜 for 10 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 polarizer after storage

With respect to the polarizing plate after the storing process, evaluation of the moisture content of the polarizing plate, the number and height of wavy defects, and the presence or absence of bubbles were carried out in the same manner as in Experiment 1. [ The results are shown in Table 2. Table 2 also shows the storage conditions and evaluation results of Reference Example 1 for comparison.

Reference Example 1 Comparative Example 2 Example 3 Example 4 Example 5 keep
Condition


Vessel - Retort pouch Desiccant - - Instrument air Nitrogen gas Silica gel Temperature (℃) 23 23 23 23 23 Relative humidity (%)
(After end of storage) 55 50 39 36 35 Duration (days) 7 10 10 10 10 evaluation
result

Polarizer water content (%) 1.9 1.9 1.7 1.6 1.6 wave
flaw several) 4 3 2 2 2 Height (nm) 3.0 2.0 2.0 2.5 2.5 Presence of bubbles U U radish radish radish

<Experiment 3>

[1] Storage of polarizer B (elimination or reduction of wave defect)

The polarizing plate (polarizing plate B) after the storage step obtained in Reference Example 1 was subjected to a storage step under the two conditions of Examples 6 to 7 below to eliminate or reduce wavy defects.

(Example 6)

200 polarizing plates B were placed in the same plastic container as that used in Comparative Example 1, and then instrument air having a relative humidity of 30% at 23 DEG C was introduced into the container, filled, sealed, and stored at 23 DEG C for 5 days. The relative humidity at the beginning of storage was 44% (relative humidity was adjusted by the introduction time of the instrument air), and the relative humidity after storage for 5 days was 45%.

(Example 7)

200 polarizing plates B were placed in the same plastic container as used in Comparative Example 1, and then instrumentation air having a relative humidity of 30% at 23 DEG C was introduced into the container, filled, sealed, and stored at 23 DEG C for 5 days. The relative humidity at the beginning of storage was 38% (relative humidity was adjusted by the introduction time of the instrument air), and the relative humidity after storage for 5 days was 40%.

[2] Evaluation of polarizer after storage

With respect to the polarizing plate after the storing process, evaluation of the moisture content of the polarizing plate, the number and height of wavy defects, and the presence or absence of bubbles were carried out in the same manner as in Experiment 1. [ The results are shown in Table 3. Table 3 also shows the storage conditions and evaluation results of Reference Example 1 for comparison.

Reference Example 1 Example 6 Example 7 keep
Condition


Vessel - Plastic containers Desiccant - Instrument air Temperature (℃) 23 23 23 Relative humidity (%)
(After end of storage) 55 45 40 Duration (days) 7 5 5 evaluation
result

Polarizer water content (%) 1.9 1.7 1.7 wave
flaw several) 4 2 2 Height (nm) 3.0 1.5 1.0 Presence of bubbles U U radish

Claims (9)

A polarizing plate comprising a polarizer and at least one protective film laminated thereon, characterized in that when a sheet is stored for 1 week under an environment of 55% relative humidity at 23 캜, a wave defect having a height exceeding 3 mm is generated at any side, Preparing a polarizing plate for generating three or more wavy defects in the polarizing plate;
Storing the polarizing plate in an environment in which the moisture content of the polarizing plate after storage is lower than the moisture content of the polarizing plate when stored for one week under the environment of 23 ° C and a relative humidity of 55%
And a polarizing plate. A polarizing plate comprising a polarizer and at least one protective film laminated thereon, comprising the steps of: preparing a polarizing plate having a wavy defect having a height of more than 3 mm at either side or having at least three wavy defects at either side;
A step of storing the polarizing plate in an environment in which the moisture content of the polarizing plate after storage is lower than the moisture content of the polarizing plate before storage
Wherein the polarizing plate comprises a polarizing plate. A polarizing plate comprising a polarizer and at least one protective film laminated thereon, characterized in that when a sheet is stored for 1 week under an environment of 55% relative humidity at 23 캜, a wave defect having a height exceeding 3 mm is generated at any side, Preparing a polarizing plate for generating three or more wavy defects in the polarizing plate;
Storing the polarizing plate in an environment in which the moisture content of the polarizing plate after storage is lower than the moisture content of the polarizing plate when stored for one week under the environment of 23 ° C and a relative humidity of 55%
And a polarizing plate. A polarizing plate comprising a polarizer and at least one protective film laminated thereon, comprising the steps of: preparing a polarizing plate having a wavy defect having a height of more than 3 mm at either side or having at least three wavy defects at either side;
A step of storing the polarizing plate in an environment in which the moisture content of the polarizing plate after storage is lower than the moisture content of the polarizing plate before storage
And a polarizing plate. The method according to any one of claims 1 to 4, wherein the step of storing includes a step of storing the polarizing plate under an environment of a relative humidity of 30 to 50%. The method according to any one of claims 1 to 4, wherein the polarizing plate in the storing step is stored in a sealed container. The method according to any one of claims 1 to 4, wherein the polarizing plate in the storing step is stored in a sealed container containing a dehumidifying agent. The method according to any one of claims 1 to 4, 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 4, 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.

Images