KR102221340B1 - Method for manufacturing polarization plate sheet - Google Patents

Abstract

A rectangular polarizing plate sheet having a long side and a short side, comprising a polarizer and a protective film laminated on at least one side thereof, wherein a first polarizing plate sheet having one or more waveform defects on at least one long side is provided. There is provided a method for manufacturing a polarizing plate sheet including a step of preparing and a step of reducing the moisture content of the first polarizing plate sheet body by 0.05% by weight or more to obtain a second polarizing plate sheet body.

Description

Manufacturing method of a polarizing plate sheet blade {METHOD FOR MANUFACTURING POLARIZATION PLATE SHEET}

The present invention relates to a method of manufacturing a polarizing plate sheet with reduced waveform defects, which is suitably used for an image display device such as a liquid crystal display device.

Polarizing plates used in image display devices such as liquid crystal displays generally have a laminated structure in which a protective film is bonded to one or both sides of a polarizer through an adhesive layer, and a long polarizer and a long protective film are used. , Manufactured as a long piece (polarizing plate roll) by a roll-to-roll method [for example, Japanese Patent Laid-Open No. 2009-134190 (Patent Document 1)]. The obtained elongated polarizing plate is cut into a sheet of a predetermined size according to the screen size of the image display device, laminated and laminated to an image display element such as a liquid crystal cell using a pressure-sensitive adhesive layer or the like, and inserted into the image display device.

In Patent Document 1, as a method for suppressing a problem called inverse curl and wave curl occurring in a polarizing plate, a long polarizer and a long protective film are superimposed with an adhesive to obtain a laminate, and then the length of the laminate It is described that the adhesive is polymerized and cured while the laminate is in close contact with a convex curved surface formed in an arc shape along the direction.

Japanese Patent Publication No. 2009-134190

According to the method described in Patent Document 1, it is possible to suppress the occurrence of the above problem at least immediately after manufacturing a long polarizing plate or immediately after cutting it into a sheet. However, even when a polarizing plate cut into a sheet member (polarizing plate sheet member) does not have the above-described problem at an initial stage, depending on the storage environment, waveform defects may be generated during storage due to moisture absorption. The "waveform defect" refers to a deformation defect in which at least one side of a sheet of a polarizing plate and an end region including the same are wave-like. When waveform defects occur in the polarizing plate sheet body, for example, when applied to a liquid crystal display device, when bonding the polarizing plate sheet body and the liquid crystal cell through the pressure-sensitive adhesive layer, the bonding interface between the pressure-sensitive adhesive layer and the liquid crystal cell, especially the bonding interface. Air bubbles are easily mixed in the end region and the vicinity thereof. If these bubbles are generated in the image display area of the liquid crystal panel, they become bright spots when lit, which can reduce the visibility of the liquid crystal display device.

Accordingly, an object of the present invention is to provide a method for manufacturing a polarizing plate sheet having a reduced number or height of corrugated defects.

The present invention provides a method for producing a sheet of a polarizing plate shown below.

[1] a rectangular polarizing plate sheet having a long side and a short side, comprising a polarizer and a protective film laminated on at least one side thereof, the first polarizing plate having one or more waveform defects on at least one long side The process of preparing the sheet frond,

Step of obtaining a second polarizing plate sheet by reducing the moisture content of the first polarizing plate sheet by 0.05% by weight or more

Containing, the manufacturing method of the polarizing plate sheetfed body.

[2] The first polarizing plate sheetfed body includes an adhesive layer,

The manufacturing method according to [1], wherein in the step of obtaining the second polarizing plate sheet member, the moisture content of the first polarizing plate sheet member is lowered within a range of less than 0.2% by weight.

[3] The manufacturing method according to [1] or [2], wherein in the step of preparing the first polarizing plate sheet member, three or more corrugated defects are present on the at least one long side.

[4] The manufacturing method according to [1] or [2], in which, in the step of preparing the first polarizing plate sheet, the height of the corrugated defect on the at least one long side exceeds 2 mm.

[5] The first polarizing plate sheet body includes the polarizer, a first protective film laminated on one side of the polarizer through a first adhesive layer, and a first protective film laminated on the other side through a second adhesive layer. 2 The production method according to any one of [1] to [4] including a protective film.

[6] The production method according to [5], in which the first protective film and the second protective film have different moisture permeability at a temperature of 40°C and a relative humidity of 90% by 30 g/(m 2 ·24 hr) or more.

[7] The production method according to [5] or [6], wherein at least one of the first adhesive layer and the second adhesive layer is formed of a cured product of an active energy ray-curable adhesive.

[8] The production method according to any one of [1] to [7], in which the moisture content is lowered by enclosing the first polarizing plate sheet body together with a humidity control agent in a moisture-proof container.

According to the present invention, a polarizing plate sheet having a reduced number or height of waveform defects can be provided. Particularly, the present invention can provide a manufacturing method capable of reducing waveform defects to a sufficient degree even for a polarizing plate sheet having three or more waveform defects, or having waveform defects having a height of more than 2 mm.

1 is a schematic cross-sectional view showing an example of a layer structure of a first polarizing plate sheet body.

The manufacturing method of the polarizing plate sheet according to the present invention, the following steps:

(1) A first polarizing plate comprising a polarizer and a protective film laminated on at least one side thereof and having a long side and a short side of a rectangular polarizing plate sheet having one or more waveform defects on at least one long side The process of preparing the sheet frond,

(2) Step of obtaining a second polarizing plate sheet by lowering the moisture content of the first polarizing plate sheet by 0.05% by weight or more

Includes. Hereinafter, each process is demonstrated.

(1) Process of preparing the first polarizing plate sheet body

The first polarizing plate sheet member is an inexpensive polarizing plate sheet member that is prone to waveform defects and is likely to be accompanied by the problem of mixing of bubbles as described above or the resulting decrease in visibility, and specifically, one in at least one long side. It is a polarizing plate sheetfed body having the above waveform defects. As a result of the occurrence of more waveform defects, the first polarizing plate sheet has a waveform defect having a height of more than 2 mm on at least one long side, or a polarizing plate sheet having three or more waveform defects on at least one long side. A blade may be sufficient, and the 1st polarizing plate sheet blade may have three or more corrugated defects in at least any one of the long sides, and any one or more of these corrugated defects may be a corrugated defect having a height of more than 2 mm.

The height of the corrugated defect is the height from the flat surface to the top of the corrugated defect in the case where the first polarizing plate sheet member is placed on the flat surface, and in this case, the first polarizing plate sheet member is an image display element (e.g., a liquid crystal cell It is placed on the flat surface with the side to be joined to) facing up. The height of the corrugated defect is measured at the side (end) of the sheet of the first polarizing plate. In addition, the number of corrugated defects is the number substantially recognized as corrugated defects, and specifically, is the number of corrugated defects whose height is 0.5 mm or more from the flat surface when the 1st polarizing plate sheet metal is placed on a flat surface. The number of waveform defects is also measured at the side (end) of the sheet of the first polarizing plate.

The first polarizing plate sheet member has a rectangular shape having a long side and a short side, and is typically a rectangle. The lengths of the long side and the short side are not particularly limited. Usually, the long side of the first polarizing plate sheeting body is 700 mm or more, and the short side is 400 mm or more. Waveform defects tend to become more pronounced as the size of the sheet of the first polarizing plate increases, in terms of the height and number of waveforms. When the size (long side and/or short side) is too small, the problem of waveform defect itself is unlikely to occur. The first polarizing plate sheetfed body may be a polarizing plate in which the above-described waveform defects occur during a process of cutting a polarizing plate manufactured as an elongated material and then storing and transporting it under certain conditions.

In general, a first polarizing plate sheet having a waveform defect of more than 2 mm in height or three or more waveform defects on any one long side often has the same degree of waveform defects on the long side opposite the long side. In addition, the first polarizing plate sheetfed body having a corrugated defect of more than 2 mm in height or three or more corrugated defects on any one long side often has a corrugated defect on two short sides as well. However, waveform defects occurring on the two short sides tend to be smaller in height and/or number than the waveform defects occurring on the long side, and the waveform defects on the short side tend to contain bubbles compared to the waveform defects on the long side. Tends to not easily cause problems. Therefore, in order to suppress the problem of mixing of air bubbles and the resulting decrease in visibility, it is very important to specifically reduce the waveform defects occurring on the long side.

The layer configuration of the first polarizing plate sheet body is not particularly limited as long as it includes a polarizer and a protective film laminated and bonded on at least one surface thereof, and a protective film may be laminated and bonded to both surfaces of the polarizer. The protective film is usually laminated and bonded on a polarizer through an adhesive layer.

The first polarizing plate sheet body may have a layer (or film) other than a polarizer and a protective film. For example, generally, a polarizing plate manufactured as an elongated material and a polarizing plate sheet formed by cutting the same are distributed in the market as a polarizing plate having a pressure-sensitive adhesive layer pre-laminated on the outer surface of the polarizing plate with a pressure-sensitive adhesive layer for bonding to an image display device (eg, liquid crystal cell) In many cases, the first polarizing plate sheet may also contain such a pressure-sensitive adhesive layer. When the pressure-sensitive adhesive layer is included, a separate film (separator) for protecting the surface (outer surface) is usually laminated on the outer surface of the pressure-sensitive adhesive layer.

In addition, the polarizing plate manufactured as a long product is usually stored or distributed as a polarizing plate roll formed by winding it up, but in order to protect the outer protective film surface during winding, a protective film (surface protective film) is provided on the protective film. It is common to put it, and in this case, it is common that the polarizing plate sheet|leaf body formed by cutting the polarizing plate also has a protective film. As in this case, the first polarizing plate sheet may include a protective film laminated on the protective film.

In addition, the protective film that the first polarizing plate sheet has a surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer is provided on the outer surface (the surface opposite to the polarizer). It may be a thing. Further, the first polarizing plate sheet member may include a layer or film having an optical function other than a polarizer. One example is a retardation film.

Fig. 1 shows an example of the layer structure of the first polarizing plate sheet body. The first polarizing plate sheet 1 shown in FIG. 1 includes 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 side 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; It includes a protective film 60 laminated on the outer surface of the first protective film 20. In addition to the polarizer 10 and the protective film (the first protective film 20, the second protective film 30), the layer configuration having the pressure-sensitive adhesive layer 40, the separate film 50, and the protective film 60, It is one of the preferable layer structures of the 1st polarizing plate sheet metal.

The polarizer 10 is an optical film having a property of absorbing linearly polarized light having a vibrating surface parallel to the optical axis and transmitting linearly polarized light having a vibrating surface orthogonal to the optical axis. It may be an adsorption-oriented polyvinyl alcohol-based resin film. As the dichroic dye, iodine or a dichroic organic dye is used. The polyvinyl alcohol-based resin constituting the polarizer 10 is a saponified product of a copolymer of vinyl acetate and other monomers copolymerizable therewith (eg, ethylene or unsaturated carboxylic acid) in addition to polyvinyl alcohol, which is a saponified product of polyvinyl acetate. It may be a phosphorus vinyl alcohol-based copolymer. The thickness of the polarizer 10 is usually about 5 µm to 40 µm.

The polarizer 10 is a process of uniaxially stretching a polyvinyl alcohol-based resin film, a process of dyeing a polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye, and a polyvinyl alcohol-based with a dichroic dye adsorbed thereto. It can be produced according to a method including a step of treating a resin film with an aqueous boric acid solution and a step of washing with water after treatment with an aqueous boric acid solution. The dyeing of the dichroic dye can be performed by immersing the film in an aqueous solution containing the dichroic dye, and the treatment with the aqueous boric acid solution can be performed by immersing the film in the aqueous boric acid solution.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing of 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. Further, uniaxial stretching may be performed in a plurality of these steps.

The first and second protective films 20 and 30 may be a light-transmitting (preferably optically transparent) thermoplastic resin film. Specific examples of the thermoplastic resin include polyolefin resins such as chain polyolefin resins (polypropylene resins, etc.) and cyclic polyolefin resins (norbornene resins, etc.); Polyester resin (polyethylene terephthalate resin, etc.); (Meth)acrylic resin (methyl methacrylate resin, etc.); Cellulose resin (triacetyl cellulose [TAC], cellulose acetate resin such as diacetyl cellulose, etc.); Polycarbonate resin; Polyvinyl alcohol-based resin; Polyvinyl acetate-based resin; Polyarylate resin; Polystyrene resin; Polyethersulfone resin; Polysulfone resin; Polyamide resin; Polyimide resin; And mixtures and copolymers thereof. The thickness of the first and second protective films 20 and 30 is, for example, about 5 µm to 200 µm, preferably 10 µm to 150 µm, and more preferably 15 µm to 100 µm. In this specification, "(meth)acryl" means at least one selected from acrylic and methacrylic.

Like the first polarizing plate sheet 1 shown in FIG. 1, a first protective film 20 is provided on one side of the polarizer 10, and a second protective film 30 is provided on the other side. In the case of providing, the first protective film 20 and the second protective film 30 may be composed of the same type of thermoplastic resin, may be composed of a different type of thermoplastic resin, but composed of a different type of thermoplastic resin. In the case where the moisture permeability of the protective film bonded to both sides is different from each other, such as when the case is formed, since the waveform defect is particularly liable to occur due to the difference in hygroscopicity, the present invention is particularly advantageous in such a case. According to the present invention, the difference in moisture permeability of the protective film bonded to both sides is 30 g/(m 2 ·24 hr) or more, further 50 g/(m 2 ·24 hr) or more, and further 100 g/(m 2 ·24 hr) or more. In particular, even if it is 300 g/(m 2 ·24 hr) or more, it is possible to obtain a sheet of a polarizing plate that does not easily cause problems such as mixing of air bubbles or lowering visibility due to reduction of corrugated defects. Usually, the difference in moisture permeability of the protective film bonded to both sides is 900 g/(m 2 ·24 hr) or less.

The moisture permeability is a moisture permeability at a temperature of 40°C and a relative humidity of 90%, and is measured according to the cup method specified in JIS Z 0208. As a combination of a protective film having a moisture permeability difference of 30 g/(m 2 ·24 hr) or more at a temperature of 40°C and a relative humidity of 90%, for example, a combination of a cellulose-based resin film (TAC film, etc.) and a cyclic polyolefin-based resin, cellulose-based A combination of a resin film (TAC film, etc.) and a (meth)acrylic resin film, a combination of a cyclic polyolefin resin and a (meth)acrylic resin film, and the like may be mentioned. In addition, even if the thermoplastic resin constituting the protective film bonded to both sides is the same type, there may be a difference in moisture permeability depending on the presence or absence of the surface treatment layer laminated thereon and the difference in type.

The polarizer 10, the first protective film 20, and the second protective film 30 can be bonded through an adhesive layer. As the adhesive for forming the adhesive layer, a water-based 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 a solvent-free adhesive, but may contain an organic solvent. When a solvent-free adhesive is used, drying treatment for removing the solvent becomes unnecessary. In the case of using an active energy ray-curable adhesive, after bonding the protective film through the adhesive layer, the adhesive layer is cured by irradiating active energy rays such as visible light, ultraviolet rays, X-rays, and electron rays, preferably ultraviolet rays. Accordingly, in this case, the adhesive layer in the first polarizing plate sheet is made of a cured product of an active energy ray-curable adhesive.

Like the first polarizing plate sheet 1 shown in FIG. 1, a first protective film 20 is provided on one surface of the polarizer 10, and a second protective film 30 is provided on the other surface. When provided, the first adhesive layer bonding the first protective film 20 and the second adhesive layer bonding the second protective film 30 may be formed of the same type of adhesive, or a different type of adhesive. Although it may be formed, it is preferably formed of the same type of adhesive from the viewpoint of manufacturing efficiency.

In the case where at least one (preferably both) of the first adhesive layer and the second adhesive layer is made of a cured product of an active energy ray-curable adhesive, waveform defects due to moisture absorption are particularly likely to occur. The invention is particularly advantageous.

As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 40 for bonding to an image display device (e.g., a liquid crystal cell), for example, a (meth)acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a polyamide-based pressure-sensitive adhesive, and a polyether-based pressure-sensitive adhesive , A fluorine-based adhesive, and a rubber-based adhesive. Among them, from the viewpoints of transparency, adhesive force, reliability, rework property, and the like, a (meth)acrylic pressure-sensitive adhesive is preferably used. The thickness of the pressure-sensitive adhesive layer 40 is usually 2 µm to 40 µm.

The separate film 50 and the protective film 60 are each provided for the purpose of temporarily protecting the pressure-sensitive adhesive layer 40 and the first protective film 20 when storing, transporting, or inspecting a polarizing plate. The separate film 50 that protects the pressure-sensitive adhesive layer 40 is peeled off immediately before the second polarizing plate sheet to be described later is provided for practical use (eg, bonded to an image display element such as a liquid crystal cell). In addition, the protective film 60 is usually peeled off for each of the pressure-sensitive adhesive layers after the second polarizing plate sheet is provided for practical use (for example, bonded to an image display element such as a liquid crystal cell).

The separate film 50 is usually composed of a thermoplastic resin film subjected to a release treatment on one side, and the release treatment surface is bonded to the pressure-sensitive adhesive layer 40. In addition, the protective film 60 is usually constituted by providing a pressure-sensitive adhesive layer on one side of a thermoplastic resin film. The thermoplastic resin constituting the separate film 50 and the protect film 60 is, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, etc. I can. As for the pressure-sensitive adhesive layer of the protective film 60, the above-described description of the pressure-sensitive adhesive layer 40 is cited.

The layer configuration of the first polarizing plate sheet member is not limited to the example shown in FIG. 1, and may be, for example, the following layer configuration.

[A] a configuration in which at least one of the pressure-sensitive adhesive layer 40, the separate film 50, and the protective film 60 is omitted,

[B] a configuration in which either 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] In addition to the first protective film 20 and the second protective film 30, a configuration having an optical compensation film such as a retardation film.

An example of the above [b] is a configuration in which the second protective film 30 is omitted, and a suitable specific example is the pressure-sensitive adhesive layer 40 on the side opposite to the first protective film 20 in the polarizer 10. ) Is directly laminated to obtain a layer configuration of the protective film 60/first protective film 20/polarizer 10/adhesive layer 40/separate film 50.

A suitable specific example of the above [c] is a protective film 60 / a first protective film 20 / a polarizer 10 / a phase difference film [the second protective film 30] / an adhesive layer 40 / a separate film ( 50). Suitable specific examples of (d) are the protective film 60 / first protective film 20 / polarizer 10 / second protective film 30 / phase difference film / adhesive layer 40 / separate film 50 ). In this case, the second protective film 30 and the retardation film may be bonded, for example, through an adhesive 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 is polyvinylidene fluoride/polymethyl methacrylate copolymer, liquid crystal polyester, acetyl cellulose, ethylene-acetic acid, in addition to those exemplified above for the first and second protective films 20 and 30. A saponified product of a vinyl copolymer, polyvinyl chloride, etc. can also be used. The draw ratio is usually about 1.01 to 6 times.

As will be described later, according to the method of the present invention, when the first polarizing plate sheet member is a polarizing plate sheet member including an adhesive layer, it is possible to suppress a deformation problem called "reverse curl" apart from the waveform defect. In the polarizing plate sheet including an adhesive layer, the pressure-sensitive adhesive layer is a surface opposite to the polarizer in the protective film or polarized light, as shown in FIG. 1 or as in the preferred specific example of [b] shown above. It can be laminated on the sleeping surface. As described above, the polarizing plate sheet body including the pressure-sensitive adhesive layer may further include a separate film laminated on the outer surface of the pressure-sensitive adhesive layer.

(2) Step of obtaining a sheet of a second polarizing plate (water content reduction step)

This step is a step of reducing the moisture content of a first polarizing plate sheet having one or more corrugated defects on at least one long side (by performing a drying treatment), and obtaining a second polarizing plate sheet leaf having reduced corrugated defects. to be.

In this step, the moisture content of the first polarizing plate sheet is reduced by 0.05% by weight or more. That is, when the moisture content of the first polarizing plate sheet body is S1 and the moisture content of the second polarizing plate sheet body is S2, the absolute value (|ΔS|) of the moisture content difference (ΔS) of S2-S1 is 0.05% by weight or more. . If |ΔS| is less than 0.05% by weight, a sufficient effect of reducing waveform defects cannot be obtained. |ΔS| is preferably 0.06% by weight or more, and more preferably 0.07% by weight or more. The method of measuring the moisture content (S1, S2) and the moisture content difference (ΔS) of the polarizing plate sheet body is in accordance with the description in the section of the following Examples.

In the case where the first polarizing plate sheet member is a polarizing plate sheet member including the aforementioned pressure-sensitive adhesive layer, |ΔS| is preferably less than 0.2% by weight, more preferably 0.18% by weight or less, and still more preferably 0.15% by weight or less. Thereby, "reverse curl" can be suppressed effectively. The term ``reverse curl'' means a polarizing plate sheet containing an adhesive layer in the absence of a separate film for protecting the adhesive layer (e.g., a polarizing plate obtained by peeling and removing the separate film from the polarizing plate sheet having a separate film on the outer surface of the adhesive layer) When the sheet member) is placed on a flat surface with the side to be bonded to the image display element (e.g., liquid crystal cell) facing up (i.e., with the adhesive layer facing up), the four corners of the polarizing plate sheet member are lifted from the flat surface. When viewed from the side, it refers to a deformation in which the sheet of the polarizing plate is U-shaped as a whole. The reverse curl is also preferably suppressed because it is likely to accompany the problem of mixing of air bubbles and a decrease in visibility due to it.

In addition, the reverse curl is usually a deformation recognized for the first time in the absence of a separate film on the pressure-sensitive adhesive layer.

As a method of appropriately reducing the moisture content of the sheet of the first polarizing plate, for example,

1) A method of maintaining (storing) the first polarizing plate sheet under a low humidity environment for a certain period of time,

2) Method of heating the sheet body of the first polarizing plate

And the like. The heating temperature in method 2) is, for example, about 35°C to 65°C. Among them, method 1) is preferably used because the quality (optical characteristics) of the resulting second polarizing plate sheet body can be better maintained, and after the waveform defect has been reduced, the state can be easily maintained. do.

As a specific example of method 1), for example,

1-1) A method of maintaining (storing) the first polarizing plate sheet material for a certain continuous period in a sealed container under a low humidity environment,

1-2) How to keep (storage) the first polarizing plate sheet body for a certain continuous period of time indoors in a low humidity environment

And the like. Among them, the method 1-1) is suitable because it does not require a burden on equipment or is suitable for transportation and distribution. The low-humidity environment may be, for example, a relative humidity of 20% to 55%, preferably 30% to 50%, and more preferably 35% to 50%. The temperature in a low-humidity environment may be, for example, about 15°C to 35°C.

The container used in Method 1-1) is a sealable container, and may be, for example, a film package, a plastic container, a metal container, or the like. As the container, it is preferable to use a container having moisture-proof properties in order to maintain an internal low-humidity environment, and examples thereof include a container having a moisture-proof layer as a representative of a multilayer film package having an aluminum layer as a moisture-proof layer.

A suitable method for setting the inside of the sealed container into a low-humidity environment (reducing the relative humidity in the sealed container) is to enclose a low-humidity inert gas (dry nitrogen, dry air, etc.) or a drying agent (dehumidifying agent) in the sealed container. In the case of using an inert gas with low humidity, the first polarizing plate sheet may be sealed and packaged in a state in which an inert gas is introduced into a sealed container and the inside of the container is replaced with the gas. In the case of using a desiccant (dehumidifying agent), the desiccant may be put in a sealed container and sealed and packaged together with the first polarizing plate sheet body.

As the drying agent (dehumidifying agent), various porous materials such as silica gel (silica gel A type, silica gel B type, etc.), zeolite, molar sieve, activated carbon, activated clay, and the like can be used. In the method 1-1), while holding (storing) the first polarizing plate sheet body, it is advantageous to maintain the relative humidity in the sealed container at an approximately certain constant value within the relative humidity range. Therefore, among the above drying agents (dehumidifying agents), it is preferable to use a humidifying agent capable of not only absorbing moisture but also discharging moisture, depending on the relative humidity of the surroundings. Silica gel B type, zeolite, activated clay, etc. can be used as a humidity control agent.

The moisture content reduction treatment (drying treatment) for the first polarizing plate sheet as described above is particularly effective for reduction of corrugated defects having a height of 2 mm or more, or three or more, but of course, a height of 2 mm or less. Also, it is effective in reducing the number of waveform defects of less than three and waveform defects on the short side.

Example

Hereinafter, the present invention will be described in more detail by showing examples, but the present invention is not limited by these examples. In the following examples, the number and height of the corrugated defects, the height of the inverted curl, and the moisture content and moisture content difference of the polarizing plate sheet body were in accordance with the following measurement method.

(Number and height of waveform defects)

With the side of the separate film 50 facing upward, the polarizing plate sheet body is placed on a flat surface, and the number of corrugated defects on the two long sides of the polarizing plate sheet body (as described above, a waveform having a height of 0.5 mm or more from the flat surface) Defects only) and the height of the corrugated defect from the flat surface were measured, respectively. Table 1 shows the number and height of waveform defects on the long side having more waveform defects among the two long sides. The height of the waveform defect shown in Table 1 is the height of the highest waveform defect in the case of having a plurality of waveform defects.

(Reverse curl height)

The separate film 50 was peeled off, the pressure-sensitive adhesive layer 40 side was turned upward, and the polarizing plate sheet was placed on a flat surface. In this state, the heights of the four leg portions from the flat surface were measured, respectively, and the maximum values thereof were taken as the height of the inverted curl.

(Moisture content (S1, S2) and moisture content difference (ΔS) of the sheet of polarizing plate)

In advance, using a plurality of polarizing plate sheet frond samples, a calibration curve (conversion formula) representing the correlation between the moisture content according to the dry gravimetric method and the measured value of the infrared absorption type moisture meter ("IM series IRMA1100S" manufactured by Chino Corporation) is as follows: expression:

The moisture content according to the dry gravimetric method (% by weight) = 22.739 x (measured value of the moisture meter) + 2.5046 was calculated. At this time, the moisture content according to the dry gravimetric method is as follows: When the weight of the polarizing plate sheet after drying at 105°C for 2 hours is W1, and the weight of the polarizing plate sheet before drying is W0, the following equation:

Moisture content (% by weight) according to the dry gravimetric method = {(W0-W1)÷W0}×100

It was obtained according to.

The moisture content (S1) of the first polarizing plate sheet body and the moisture content (S2) of the second polarizing plate sheet body in the following examples are measured using the moisture meter, and this is substituted into the calibration curve (conversion formula), It is converted to the moisture content (% by weight) according to the dry weight method. By subtracting S1 from S2, the moisture content difference (ΔS) between the moisture content (S2) of the second polarizing plate sheet body and the moisture content (S1) of the first polarizing plate sheet body was calculated.

<Example 1>

[1] Preparation of the first polarizing plate sheetfed body

A long polarizing plate having a layer structure shown in FIG. 1 was prepared. The layer configuration of this polarizing plate is a protective film 60 having a thickness of 53 μm (consisting of a (meth)acrylic pressure-sensitive adhesive layer and a polyethylene terephthalate film)/the first protective film 20 (TAC film) having a thickness of 60 μm/thickness 25 Μm polarizer 10 (uniaxially stretched polyvinyl alcohol film in which iodine is adsorbed and oriented) / second protective film 30 having a thickness of 52 µm (phase difference film made of cyclic polyolefin resin) / pressure-sensitive adhesive layer having a thickness of 20 µm ( 40) ((meth)acrylic pressure-sensitive adhesive layer)/38 µm-thick separate film 50 (polyethylene terephthalate film subjected to a release treatment on one side). All of the first protective film 20 and the second protective film 30 are active energy ray-curable adhesives (made by ADEKA Co., Ltd., which are ultraviolet-curable adhesives containing a curable compound that is a cationic polymerizable epoxy-based compound and a photo-cationic polymerization initiator) It is bonded to the polarizer 10 through an adhesive layer made of a cured product of "KR-70T"). In addition, the moisture permeability of the first protective film 20 and the second protective film 30 at 40° C. and 90% relative humidity was 560 g/(m 2 ·24 hr) and 5 g/(m 2 ·24 hr), respectively. hr).

From the long polarizing plate, a 46-inch-sized (long side 1031 mm x short side 585 mm) rectangular polarizing plate sheeting was cut out, and then stored for 7 days in an environment of 23°C and 55% relative humidity, and the waveform height according to the measurement method Was 1.0 mm, and a first polarizing plate sheet having a long side in which the number of corrugated defects was 3 was obtained.

[2] Fabrication of the second polarizing plate sheet (water content reduction process)

In a retort pouch using an aluminum layer as a moisture-proof layer, one sheet of the first polarizing plate sheet obtained above was put, and 8 g of a humidity control agent (silica gel type B) and a temperature-humidity meter ("TR-77Ui" manufactured by T&D CORP.) were put into the retort pouch. , The retort pouch was sealed and stored for 7 days in a room under a constant temperature environment to obtain a second polarizing plate sheet body. For 7 days of storage, except at the beginning of storage, the temperature and relative humidity in the retort pouch were approximately constant and were 21° C. and 48.0%, respectively.

<Example 2>

Table shows the temperature and relative humidity in the retort pouch for 7 days of storage, using a first polarizing plate sheet having a long side with a corrugated height of 0.5 mm and a number of corrugated defects of 4, using 16 g of silica gel type B. Except having done it as shown in 1, it carried out similarly to Example 1, and obtained the 2nd polarizing plate sheet|leaf body.

<Example 3>

A second polarizing plate sheet was obtained in the same manner as in Example 1, except that 32 g of silica gel type B was used and the temperature and relative humidity in the retort pouch during storage for 7 days were as shown in Table 1.

<Example 4>

The second polarizing plate was carried out in the same manner as in Example 1, except that 80 g of silica gel type A was used instead of the silica gel type B, and the temperature and relative humidity in the retort pouch for 7 days of storage were as shown in Table 1. A sheet body was obtained.

<Example 5>

Using a first polarizing plate sheet body having a long side with four corrugated defects, 80 g of silica gel type A, and using a moisture-proof plastic container instead of a retort pouch for storage of the first polarizing plate sheet body 7 A second polarizing plate sheet was obtained in the same manner as in Example 1 except that the daily temperature and relative humidity were as shown in Table 1.

The moisture content (S1) of the first polarizing plate sheet member before the moisture content reduction process, the number and height of waveform defects, the moisture content (S2) of the second polarizing plate sheet member after the moisture content reduction step, and the number, height and height of the inverted curls are determined. It was measured according to the method described above. Table 1 shows the results. Table 1 also shows the calculation results of the moisture content difference (ΔS).

1: first polarizing plate sheet, 10: polarizer, 20: first protective film, 30: second protective film, 40: pressure-sensitive adhesive layer, 50: separate film, 60: protective film.

Claims (11)

A rectangular polarizing plate sheet having a long side and a short side, comprising a polarizer and a protective film laminated on at least one side thereof, wherein a first polarizing plate sheet having one or more waveform defects on at least one long side is provided. The preparation process,
Step of obtaining a second polarizing plate sheet by lowering the moisture content of the first polarizing plate sheet body in a range of 0.05% by weight or more and less than 0.2% by weight
Containing, the manufacturing method of the polarizing plate sheetfed body. delete The manufacturing method according to claim 1, wherein in the step of preparing the first polarizing plate sheet member, there are three or more corrugated defects in the at least one long side. delete The manufacturing method according to claim 1, wherein in the step of preparing the first polarizing plate sheet member, the height of the corrugated defect in the at least one long side exceeds 2 mm. delete The first protective film according to any one of claims 1, 3, and 5, wherein the first polarizing plate sheet member includes the polarizer, and a first protective film laminated on one side of the polarizer through a first adhesive layer, The manufacturing method comprising a second protective film laminated on the other side through a second adhesive layer. The manufacturing method according to claim 7, wherein the first protective film and the second protective film have different moisture permeability at a temperature of 40°C and a relative humidity of 90% by 30 g/(m 2 ·24 hr) or more. The manufacturing method according to claim 7, wherein at least one of the first adhesive layer and the second adhesive layer is made of a cured product of an active energy ray-curable adhesive. The manufacturing method according to claim 8, wherein at least one of the first adhesive layer and the second adhesive layer is made of a cured product of an active energy ray-curable adhesive. The manufacturing method according to any one of claims 1, 3, and 5, wherein the moisture content is lowered by enclosing the first polarizing plate sheet body together with a humidity control agent in a moisture-proof container.

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