KR20210100658A - Polarizer - Google Patents

Abstract

[Problem] A polarizing plate having a concave portion on the outer edge and/or a through hole in the plane in a planar view, cracking occurs in a cold/heat shock test (heat shock test) repeatedly exposed under low-temperature and high-temperature conditions To provide this suppressed polarizing plate.
[Solution] A polarizer comprising a polyvinyl alcohol-based resin film, and a first thermoplastic resin film provided on one side thereof, wherein the shrinkage force per 2 mm of width in the absorption axis direction of the polarizer is 0.7 N or less, and the first thermoplastic The elastic modulus at 23 degreeC of a resin film is 3000 N/m<2> or less, In planar view, a polarizing plate which has a recessed part in an outer edge part, or has a through-hole in plane.

Description

Polarizer

The present invention relates to a polarizing plate.

In recent years, the design of an image display apparatus is diversifying. Under the influence of the trend, it is calculated|required that a polarizing plate also respond|corresponds to various shapes.

Patent Document 1: Japanese Patent Laid-Open No. 2017-182017

A polarizing plate which has a concave part in an outer edge part, and/or has a through-hole in surface may generate|occur|produce a crack in the periphery of a recessed part and a through-hole.

An object of the present invention is a polarizing plate having a concave portion on the outer edge portion in a planar view and/or a through hole in the surface, in a cold-heat shock test (heat shock test) repeatedly exposed under low-temperature and high-temperature conditions. It is to provide a polarizing plate in which the occurrence of cracks is suppressed.

MEANS TO SOLVE THE PROBLEM This invention provides the manufacturing method of the following polarizing plate, an image display apparatus, and a polarizing plate.

[1] A polarizer comprising a polyvinyl alcohol-based resin film, and a polarizing plate comprising a first thermoplastic resin film provided on one side thereof,

The polarizer has a contraction force per 2 mm in width in the absorption axis direction of 0.7 N or less,

The elastic modulus at 23° C. of the first thermoplastic resin film is 3000 N/m 2 or less,

The said polarizing plate has a concave part in an outer edge part, or a polarizing plate which has a through-hole in a plane in planar view.

[2] The polarizing plate according to [1], wherein the first thermoplastic resin film is an acrylic resin film or a cyclic polyolefin-based (COP) resin film.

[3] The polarizing plate according to [1] or [2], further comprising a second thermoplastic resin film provided on the other surface of the polarizer.

[4] The polarizing plate with an adhesive layer which has the polarizing plate in any one of [1]-[3], and the adhesive layer provided in the 1st thermoplastic resin film side of the said polarizing plate.

[5] The polarizing plate with a pressure-sensitive adhesive according to [4], wherein the pressure-sensitive adhesive layer is for bonding the polarizing plate to an image display element.

[6] An image display device comprising the polarizing plate according to any one of [1] to [3].

[7] A method for producing a polarizing plate according to any one of [1] to [3], comprising:

It is a process of preparing a polarizer, A preparation process including a 1st annealing process;

A bonding step of bonding the polarizer and the first thermoplastic resin film;

a second annealing process;

A mold release processing step of providing a concave portion on the outer edge of the polarizing plate or providing a through hole in the surface

A manufacturing method comprising a.

According to the present invention, a polarizing plate having a concave portion on the outer edge portion in a planar view and/or having a through hole in the surface, cracked in a cold-heat shock test (heat shock test) repeatedly exposed under low-temperature and high-temperature conditions It is possible to provide a polarizing plate in which the occurrence of is suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the polarizing plate which concerns on one aspect of this invention.
2 is a schematic diagram showing an example of a concave portion;
3 is a schematic diagram showing a polarizing plate according to an embodiment of the present invention.
4 is a schematic diagram showing an example of a through hole.
5 is a schematic diagram showing an example of the relationship between the depth direction of the concave portion and the stretching direction.
It is a schematic sectional drawing which shows the polarizing plate which concerns on one aspect of this invention.
It is a flowchart which shows the manufacturing method of a polarizer.
Fig. 8 is a schematic diagram showing a polarizing plate produced in Examples.

<Polarizer>

The polarizing plate which concerns on this invention is a polarizing plate containing the polarizer containing a polyvinyl alcohol-type resin film, and the 1st thermoplastic resin film provided in the one surface. A polarizing plate may have a concave part in a planar view WHEREIN: A polarizing plate which has a concave part in an outer edge part, or has a through-hole in plane, has the said recessed part in an outer edge part, has a through-hole in a plane, and has all these. The concave portion of the outer edge portion and the in-plane through hole may be collectively referred to as a deformed portion hereinafter in some cases. In this specification, planar view means seeing from the thickness direction of a layer.

The polarizing plate may be a quadrangle or a rounded quadrangle in plan view. A rounded rectangle refers to a shape in which at least one of the corners of the rectangle is curved, that is, at least one of the corners of the rectangle is a rounded shape, and a rectangle refers to a shape in which all four corners are not rounded. do. In addition, in this specification, a quadrangle shall mean a rectangle or a square. When the polarizing plate is a rounded rectangle, one or more of the four corners of the polarizing plate may be rounded.

The radius of curvature of the rounding portion may be, for example, 1 mm or more and 10 mm or less, and preferably 2 mm or more and 8 mm or less.

A polarizing plate according to an embodiment of the present invention is a rounded rectangular polarizing plate 10 having concave portions 11 and 12 on the outer edge, as shown in FIG. 1 . In the polarizing plate 10, three of the four corners of the quadrangle are rounded.

The concave portion 11 has a shape that is concave toward the inside from the outer edge in a plan view, and the depth of the concave portion may be, for example, 0.1 mm or more, preferably 0.5 mm or more, more preferably 1 mm or more. . On the other hand, the depth of the recess is usually 7 mm or less.

The outer edge portion 13 constituting the concave portion 11 may or may not be at right angles.

In addition, the outer edge part 13 may be round, and may not be round. When the outer edge portion 13 is rounded, the radius of curvature may be, for example, 0.1 mm or more and 10 mm or less, and preferably 0.5 mm or more and 5 mm or less.

The inner edge portion 14 constituting the concave portion 11 may or may not be at right angles.

In addition, the inner edge part 14 may be round, and may not be round. When the outer edge portion 14 is rounded, the radius of curvature may be, for example, 0.1 mm or more and 1 mm or less, and preferably 0.5 mm or more and 5 mm or less.

The concave portion 12 has a U-shaped concave portion shape in plan view, and the depth of the concave portion may be, for example, 0.5 mm or more and 10 mm or less, and preferably 1 mm or more and 8 mm or less.

The inner edge portion 15 constituting the concave portion 12 may have, for example, a radius of curvature of 0.5 mm or more and 15 mm or less, and preferably 1 mm or more and 10 mm or less.

The shape of the concave portion 11 is not particularly limited, and may be, for example, a shape as shown in FIGS. 2A to 2D.

As shown in Fig. 3, the polarizing plate according to another embodiment of the present invention is a rounded rectangular polarizing plate 20 having a through hole 21 in the plane in plan view. In the polarizing plate 20, four of the four corners of the quadrangle are rounded.

Although the through hole 21 is shown as a circular through hole in FIG. 3, it is not limited to this, For example, it may be an ellipse, a rectangle, a rounded rectangle, or a combination shape etc. these.

The radius of the through hole 21 may be, for example, 0.5 mm or more and 30 mm or less, and preferably 1 mm or more and 10 mm or less.

The shape of the through hole 21 is not particularly limited, and may be, for example, a shape shown in FIGS. 4A to 4D . One may be sufficient as the number of the through-holes 21, and two or more may be sufficient as it.

According to the present inventor, when a polarizing plate has the above-mentioned mold-shaped part, it was discovered that it is easy to generate|occur|produce around the mold-shaped part. Cracks in the present invention can be observed after exposure to a high-temperature environment. The conditions and observation methods under which cracks can be observed are the conditions and methods described in the Examples column to be described later.

Although the generation principle of a crack is estimated as follows, this invention is not limited to this. When the polarizing plate is exposed to a high-temperature environment, the polarizer contracts along the stretching axis, that is, along the absorption axis, while the first thermoplastic resin film is difficult to contract, thereby causing distortion between the polarizer and the first thermoplastic resin film. When the polarizing plate has a release portion, in the vicinity of the release portion, shrinkage occurs even if the polarizer follows the shape of the release portion, and the distortion between the polarizer and the thermoplastic resin film increases compared to the case where the polarizer does not have the release portion, so cracks occur. assumed to be easy to do. As for the crack, there exists a tendency for a crack to become easy to generate|occur|produce, so that the elasticity modulus of a 1st thermoplastic resin film is low.

The direction of the stretching axis (absorption axis) of the polarizer with respect to the polarizing plate is not particularly limited, but, for example, when the polarizing plate is rectangular in plan view, it may be a direction parallel to the long side direction, or it may be a direction parallel to the short side direction, , or an angle formed with the long side direction (or the short side direction) may be a direction of 45 ± 5 degrees, preferably a direction of 45 ± 2 degrees.

Further, according to the present inventors, it was found that cracks tend to occur around the mold part when the shortest distance between the center of gravity of the mold part and the polarizing plate is, for example, 40 mm or more, preferably 50 mm or more, and more preferably 60 mm or more. . This means that as the position where the mold part is provided is farther from the center of gravity, the amount of shrinkage of the polarizer in the vicinity of the mold part increases, while the first thermoplastic resin film hardly shrinks even in the vicinity of the mold part regardless of the position where the part is provided. tends to Therefore, it is estimated that the distortion between a polarizer and a thermoplastic resin film increases, and a crack becomes easy to generate|occur|produce, so that the position where a mold release part is provided is farther from a center of gravity.

The center of gravity of the polarizing plate may be defined as an intersection point of diagonal lines, for example, when the polarizing plate has a quadrangular shape. In the case where the polarizing plate is a rounded quadrangle, or when the corner is lost due to the concave portion, the intersection point may be used as an intersection when the rounded portion is substituted with the corner portion to form a diagonal line.

Moreover, it was discovered that a crack is easy to generate|occur|produce in the periphery of a mold release part, when a mold release part is located in the area|region exceeding 20% of area equivalent diameter from the center of gravity of a polarizing plate. As the position where the release part is provided is farther from the center of gravity, the amount of shrinkage of the polarizer in the vicinity of the release part increases, while the first thermoplastic resin film tends to be difficult to shrink even in the vicinity of the release part regardless of the position where the release part is provided. there is. Therefore, it is estimated that the distortion between a polarizer and a thermoplastic resin film increases, and a crack becomes easy to generate|occur|produce, so that the position where a mold release part is provided is farther from a center of gravity.

The diameter equivalent to 20% of the area from the center of gravity means a radius of a circle whose area corresponds to 20% of the total area of the polarizing plate when a circle centered on the center of gravity is superposed on the polarizing plate in plan view .

The polarizing plate may have a release portion in a region exceeding a diameter equivalent to 30% of an area from the center of gravity of the polarizing plate, or may have a release portion in a region exceeding a diameter equivalent to 40% of the polarizing plate.

Moreover, this inventor also discovered that there exists a tendency for a crack to generate|occur|produce easily, when the depth direction of the recessed part of the outer edge part of a polarizing plate and the absorption axis direction correspond. As such a polarizing plate, for example, it is a rectangular polarizing plate with a rounded planar view shape provided with the concave part 41 shown in FIG. 5, has the concave part 41 on the short side 42, and the concave part 41 is and a polarizing plate including the central point 43 of the short side 42 and the depth direction of the concave portion 41 in the absorption axis direction.

The thickness of a polarizing plate can be 5 micrometers or more and 200 micrometers or less normally, 150 micrometers or less may be sufficient, and 120 micrometers or less may be sufficient as it.

A polarizing plate is equipped with the 1st thermoplastic resin film provided in the polarizer and the one surface. The polarizing plate 100 shown in FIG. 6 is equipped with the 1st thermoplastic resin film 102 on the polarizer 101 and one surface of the polarizer 101. As shown in FIG. In addition, the polarizing plate 100 may further include a second thermoplastic resin film 103 on the other surface of the polarizer 101 . Hereinafter, the first thermoplastic resin film 102 and the second thermoplastic resin film 103 are also referred to as a thermoplastic resin film.

[Polarizer]

The polarizer 101 is a polarizer including a polyvinyl alcohol-based resin film, and may be, for example, a polarizer in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol-based resin film. Such a polarizer can be manufactured according to the manufacturing method of the polarizer mentioned later. The polarizer 101 may be an absorption type polarizer having a property of absorbing linearly polarized light having an oscillation plane parallel to the absorption axis and transmitting linearly polarized light having an oscillation plane perpendicular to the absorption axis (parallel to the transmission axis). . The polarizer 101 can be used as the polarizing plate 100 by bonding the first thermoplastic resin film 102 to one surface thereof with an adhesive, an adhesive, or the like.

The contracting force per 2 mm in width in the absorption axis direction of the polarizer 101 (hereinafter also simply referred to as "contraction force") is 0.7 N or less. Since the contractile force of the polarizer 101 is 0.7 N or less, in the polarizing plate 100 of the present invention, the elastic modulus at 23° C. of the first thermoplastic resin film is 3000 N/m 2 or less, and even if it has a mold release part, the periphery of this mold part tends to be less prone to cracking. The contractile force of the polarizer 101 is measured according to the measuring method demonstrated in the column of the Example mentioned later.

The contractile force of the polarizer 101 is preferably 0.65 N or less, and 0.6 N or less from the viewpoint of suppressing light leakage. On the other hand, the contractile force of the polarizer 101 is usually 0.1 N or more. As a method of making the contraction force of the polarizer 101 into 0.7 N or less, adjustment of the boric acid concentration in the bridge|crosslinking process mentioned later, implementation of an annealing process, etc. are mentioned, for example.

The thickness of the polarizer 101 is normally 20 micrometers or less, Preferably it is 18 micrometers or less, More preferably, it is 15 micrometers or less. Reducing the thickness of the polarizer 101 is advantageous in reducing the thickness of the polarizing plate 100 . The thickness of the polarizer 101 is usually 1 μm or more, and may be, for example, 5 μm or more.

The thickness of the polarizer 101 can be controlled, for example, by selection of a polyvinyl alcohol-based resin film, adjustment of a draw ratio, or the like.

[Method for manufacturing polarizer]

The manufacturing method of the polarizer 101 is demonstrated, referring drawings. The manufacturing method shown in FIG. 7 includes the following steps:

A swelling step (S10) of immersing the polyvinyl alcohol-based resin film in a swelling tank containing a treatment liquid containing water;

A dyeing step (S20) of immersing the polyvinyl alcohol-based resin film in a dyeing tank containing a treatment liquid containing a dichroic dye and dyeing;

A cross-linking step (S30) of immersing the polyvinyl alcohol-based resin film in a cross-linking tank containing a treatment liquid containing a cross-linking agent for cross-linking treatment;

A washing step (S40) of immersing the polyvinyl alcohol-based resin film in a washing tank;

Drying process (S50)

may include.

The polyvinyl alcohol-based resin film is uniaxially stretched in any one or more steps of the polarizer manufacturing process, more specifically, in any one or more steps from before the swelling process (S10) to the crosslinking process (S30) (stretching process).

The manufacturing method may further include processes other than those described above, and a specific example thereof may be a first annealing process (S60) and the like as shown in FIG. 7 .

The various treatment processes included in the manufacturing method which concerns on this invention can be performed continuously by conveying the polyvinyl alcohol-type resin film which is a raw film continuously along the film conveyance path|route of a polarizer manufacturing apparatus. The film conveyance path is equipped with the facilities (processing tank, a furnace, etc.) for implementing the said various processing process in these implementation order.

A film conveyance path|route can be constructed by arrange|positioning a guide roll, a nip roll, etc. at appropriate positions other than the said installation. For example, a guide roll can be arrange|positioned in the front and back of each processing tank, or in a processing tank, and can perform introduction and immersion of the film to a processing tank, and take-out from a processing tank by this. More specifically, a film can be immersed in each processing tank by providing two or more guide rolls in each processing tank, and conveying a film along these guide rolls.

As a polyvinyl alcohol-type resin which comprises the polyvinyl alcohol-type resin film which is a raw film, what saponified polyvinyl acetate-type resin can be used. As polyvinyl acetate-type resin, the copolymer of vinyl acetate and other monomer copolymerizable to this other than polyvinyl acetate which is a homopolymer of vinyl acetate is illustrated. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group. The degree of saponification of the polyvinyl alcohol-based resin is usually about 85 mol% or more, preferably about 90 mol% or more, and more preferably about 99 mol% or more. In this specification, "(meth)acryl" means at least one chosen from acryl and methacryl. The same applies to "(meth)acryloyl".

The polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral, etc. modified with aldehydes may be used.

The average degree of polymerization of polyvinyl alcohol-type resin becomes like this. Preferably it is 100 or more and 10000 or less, More preferably, it is 1500 or more and 8000 or less, More preferably, it is 2000 or more and 5000 or less. The average degree of polymerization of polyvinyl alcohol-type resin can be calculated|required based on JISK6726 (1994). When the average degree of polymerization is less than 100, it is difficult to obtain desirable polarization performance, and when it exceeds 10000, the film processability may be inferior.

The thickness of the polyvinyl alcohol-based resin film is, for example, about 10 µm or more and 50 µm or less, and from the viewpoint of setting the thickness of the polarizer to 15 µm or less, preferably 40 µm or less, more preferably 30 µm or less.

The polyvinyl alcohol-type resin film which is a raw film can be prepared, for example as a roll (wound article) of a long unstretched or stretched polyvinyl alcohol-type resin film. In this case, the polarizer can also be obtained as a long article. Hereinafter, each process is demonstrated in detail.

(1) swelling step (S10)

The swelling treatment in this step is a treatment carried out as needed for the purpose of removing foreign substances from the polyvinyl alcohol-based resin film, which is a raw film, removing a plasticizer, imparting dichromaticity, plasticizing the film, etc. Specifically, it may be a treatment in which a polyvinyl alcohol-based resin film is immersed in a swelling tank containing a treatment liquid containing water. The said film may be immersed in one swelling tank, and may be immersed in two or more swelling tanks sequentially. Before a swelling process, at the time of a swelling process, or before a swelling process and at the time of a swelling process, you may perform a uniaxial stretching process with respect to a film.

The treatment liquid accommodated in the swelling tank may be water (eg, pure water) or an aqueous solution to which a water-soluble organic solvent such as alcohol is added.

The temperature of the processing liquid accommodated in the swelling tank at the time of immersing a film is about 10 degreeC or more and 70 degrees C or less normally, Preferably it is about 15 degreeC or more and 50 degrees C or less, The immersion time of a film is 10 second or more and 600 second or less normally. degree, Preferably it is about 20 second or more and 300 second or less.

(2) Dyeing process (S20)

The dyeing treatment in this step is a treatment performed for the purpose of adsorbing and orienting the dichroic dye to the polyvinyl alcohol-based resin film, specifically, a polyvinyl alcohol-based dyeing tank containing a treatment solution containing the dichroic dye. It may be a treatment in which the resin film is immersed. The said film may be immersed in one dyeing tank, and may be immersed sequentially in two or more dyeing tanks. In order to improve the dyeability of a dichroic dye, the uniaxial stretching process to a certain extent may be given to the film used for a dyeing process at least. Instead of the uniaxial stretching treatment before the dyeing treatment, or in addition to the uniaxial stretching treatment before the dyeing treatment, a uniaxial stretching treatment may be performed at the time of the dyeing treatment.

The dichroic dye may be iodine or a dichroic organic dye. Specific examples of the dichroic organic dye include Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet. B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Super Orange GL, Direct Sky Blue , Direct First Orange S, and First Black. A dichroic dye may be used individually by 1 type, and may use 2 or more types together.

When using iodine as a dichroic dye, the aqueous solution containing iodine and potassium iodide can be used for the processing liquid accommodated in a dyeing tank. Instead of potassium iodide, other iodides, such as zinc iodide, may be used, and potassium iodide and another iodide may be used together. In addition, compounds other than iodide, such as boric acid, zinc chloride, cobalt chloride, etc. may be coexistent. When boric acid is added, it is distinguished from the crosslinking process mentioned later at the point containing an iodine. Content of the iodine in the said aqueous solution is 0.01 mass part or more and 1 mass part or less per 100 mass parts of water normally. Moreover, content of iodides, such as potassium iodide, is 0.5 mass part or more and 20 mass parts or less per 100 mass parts of water normally. As described above, the treatment liquid accommodated in the dyeing tank may contain a zinc salt.

The temperature of the processing liquid accommodated in the dyeing tank at the time of immersing a film is 10 degrees C or more and 45 degrees C or less normally, Preferably it is 10 degrees C or more and 40 degrees C or less, More preferably, they are 20 degrees C or more and 35 degrees C or less, immersion of a film Time is 30 second or more and 600 second or less normally, Preferably they are 60 second or more and 300 second or less.

When using a dichroic organic dye as a dichroic dye, the aqueous solution containing a dichroic organic dye can be used for the processing liquid accommodated in a dyeing tank. Content of the dichroic organic dye in the said aqueous solution is 1x10 ^-4 mass part or more and 10 mass parts or less ^{per 100 mass parts of water normally, Preferably they are 1x10 -3} mass part or more and 1 mass part or less. The dyeing tank may be made to coexist with a dyeing aid, etc., for example, inorganic salts, such as sodium sulfate, surfactant, etc. may be contained. A dichroic organic dye may be used individually by 1 type, and may use 2 or more types together. The temperature of the treatment liquid accommodated in the dyeing tank at the time of immersing the film is, for example, 20°C or more and 80°C, preferably 30°C or more and 70°C or less, and the immersion time of the film is usually 30 seconds or more and 600 seconds or less, preferably is greater than or equal to 60 seconds and less than or equal to 300 seconds.

(3) Crosslinking step (S30)

The crosslinking treatment of treating the polyvinyl alcohol-based resin film with a crosslinking agent after the dyeing step is a treatment performed for the purpose of water resistance or color adjustment by crosslinking, specifically, in a treatment solution contained in a crosslinking tank containing a crosslinking agent after the dyeing step It may be a treatment in which the film is immersed.

The said film may be immersed in one crosslinking tank, and may be immersed in two or more crosslinking tanks sequentially. You may perform a uniaxial stretching process at the time of a crosslinking process.

As a crosslinking agent, a boric acid, a glyoxal, glutaraldehyde, etc. are mentioned, A boric acid is used preferably. Two or more types of crosslinking agents can also be used together. Content of boric acid in the processing liquid accommodated in a crosslinking tank is 0.1 mass part or more and 15 mass parts or less normally per 100 mass parts of water, From a viewpoint of the contractile force of a polarizer, Preferably they are 1 mass part or more and 10 mass parts or less.

When the dichroic dye is an iodine, it is preferable that the processing liquid accommodated in a crosslinking tank contains iodide in addition to boric acid. Content of the iodide in the processing liquid accommodated in a crosslinking tank is 0.1 mass part or more and 15 mass parts or less per 100 mass parts of water normally, Preferably they are 5 mass parts or more and 12 mass parts or less. Potassium iodide, zinc iodide, etc. are mentioned as an iodide. Further, a compound other than iodide, such as zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate and the like, may coexist in the crosslinking tank.

The temperature of the processing liquid accommodated in the crosslinking tank at the time of immersing a film is 50 degrees C or more and 85 degrees C or less normally, Preferably it is 50 degrees C or more and 70 degrees C or less, The immersion time of a film is 10 seconds or more and 600 seconds or less normally, Preferably it is Usually 20 seconds or more and 300 seconds or less.

In a crosslinking process (S30), two or more sets of crosslinking tanks may be sufficient. In this case, the composition and temperature of the processing liquid accommodated in each crosslinking tank may be same or different. The processing liquid accommodated in the crosslinking tank may have the density|concentration and temperature of a crosslinking agent, iodide, etc. according to the objective of immersing a polyvinyl alcohol-type resin film. You may perform the bridge|crosslinking process for the waterproofing by bridge|crosslinking, and the bridge|crosslinking process for hue adjustment (complementary color), respectively in a plurality of steps (for example, a plurality of tanks).

In general, when both crosslinking treatment for waterproofing by crosslinking and crosslinking treatment for color adjustment (complementary color) are performed, a tone (complementary color tone) for performing crosslinking treatment for color adjustment (complementary color) is disposed at the rear end . The temperature of the processing liquid accommodated in the complementary color tone is, for example, 10°C or more and 55°C or less, and preferably 20°C or more and 50°C or less. Content of the crosslinking agent in the processing liquid accommodated in the complementary color tone is, for example, 1 mass part or more and 5 mass parts or less per 100 mass parts of water. The content of iodide in the treatment liquid accommodated in the complementary color tone is, for example, 3 parts by mass or more and 30 parts by mass or less per 100 parts by mass of water.

As described above, in manufacturing the polarizer, the polyvinyl alcohol-based resin film is uniaxially stretched in any one or two or more steps from before the swelling process (S10) to the crosslinking process (S30) (stretching process, FIG. 1 ) ). From the viewpoint of improving the dyeability of the dichroic dye, the film provided for the dyeing process is preferably a film subjected to at least some degree of uniaxial stretching treatment, or instead of the uniaxial stretching treatment before the dyeing treatment, or uniaxial stretching before the dyeing treatment In addition to the treatment, it is preferable to perform a uniaxial stretching treatment at the time of the dyeing treatment.

The uniaxial stretching process may be either dry stretching in which stretching is performed in the air or wet stretching in which stretching is performed in a tank, or both of these stretching may be performed. The uniaxial stretching treatment may be inter-roll stretching, hot-roll stretching, tenter stretching, etc. in which a longitudinal uniaxial stretching is performed with a circumferential speed difference between two nip rolls, but preferably inter-roll stretching is included. The draw ratio on the basis of the raw film (when the stretching treatment is performed in two or more stages, these cumulative draw ratios) is about 3 times or more and 8 times or less. In order to provide good polarization properties, the draw ratio is preferably 4 times or more, more preferably 5 times or more.

A boron component is contained in the polarizer obtained by passing through a bridge|crosslinking process (S30). There exists a tendency for shrinkage force to be made small, so that there is little content of this boron component. In order to reduce content of a boron component, what is necessary is just to lower|hang the boric acid content in the processing liquid of a crosslinking tank, or to shorten the immersion time in a crosslinking tank.

(4) cleaning process (S40)

The washing treatment in this step is a treatment carried out as needed for the purpose of removing a chemical such as an excess crosslinking agent or a dichroic dye adhering to the polyvinyl alcohol-based resin film, and is a crosslinking step using a washing solution containing water. It is a process of washing|cleaning the polyvinyl alcohol-type resin film later. Specifically, it may be a treatment in which the polyvinyl alcohol-based resin film after the crosslinking process is immersed in the treatment liquid (washing liquid) accommodated in the cleaning tank. The said film may be immersed in one washing tank, and may be immersed in two or more washing tanks sequentially. Alternatively, the washing treatment may be a treatment of spraying a washing liquid as a shower onto the polyvinyl alcohol-based resin film after the crosslinking step, or a combination of the immersion and spraying.

The washing liquid may be water (eg, pure water) or an aqueous solution to which a water-soluble organic solvent such as alcohol is added. The temperature of the cleaning solution may be, for example, about 5°C or higher and 40°C or lower.

The washing process (S40) is an arbitrary process and may be omitted, Preferably, the drying process (S50) is performed with respect to the film after performing the washing|cleaning process (S40).

(5) Drying process (S50)

A drying process (S50) is a zone for drying the polyvinyl alcohol-type resin film after a washing|cleaning process (S40). A drying process can be performed by introduce|transducing the said film into a drying process (S50), continuing conveying the polyvinyl alcohol-type resin film after a washing|cleaning process (S40), and a polarizer is obtained by this.

A drying process is performed using the drying means (heating means) of a film. A suitable example of a drying means is a drying furnace. The drying furnace is preferably one capable of controlling the temperature inside the furnace. The drying furnace is, for example, a hot air oven capable of raising the temperature inside the furnace by supplying hot air or the like. In addition, the drying treatment by the drying means may be a treatment of adhering the polyvinyl alcohol-based resin film after the washing step (S40) to one or two or more heating elements having a convex curved surface, or a treatment of heating the film using a heater. .

Examples of the heating element include a roll (eg, a guide roll also serving as a heating roller) having a heat source (eg, a heating medium such as hot water or an infrared heater) therein to increase the surface temperature. Examples of the heater include an infrared heater, a halogen heater, and a panel heater.

It is preferable that the temperature (for example, furnace internal temperature of a drying furnace, the surface temperature of a hot roll, etc.) of a drying process is 30 degreeC or more and 100 degrees C or less normally. Although the drying time in particular is not restrict|limited, For example, it is 30 second or more and 600 second or less.

(6) first annealing process (S60)

It can be set as the 1st annealing process (S60) by making the drying temperature in a drying process (S50) high or lengthening for the purpose of making the shrinkage force of a polarizer low.

The heating temperature in the first annealing process may be, for example, 80°C or higher and 100°C or lower. As for the heating temperature, there exists a tendency for a polarizer to become low-shrinkage with a higher one.

The heating time is, for example, 30 seconds or more and 600 seconds or less. As for the heating time, there exists a tendency for a long one to make a polarizer low-shrink easily.

Heating can be performed using, for example, a normal heating furnace. An example of the heating furnace may be a temperature-controllable hot air oven or an infrared heater.

Through the above process, the polarizer in which the dichroic dye is adsorbed-oriented to the polyvinyl alcohol-type resin film uniaxially stretched can be obtained.

The obtained polarizer can also be conveyed to the next polarizing plate preparation process (process of bonding a thermoplastic resin film to one side or both surfaces of a polarizer) as it is, for example.

[First Thermoplastic Resin Film]

The first thermoplastic resin film 102 has an elastic modulus at 23°C (hereinafter simply referred to as “elastic modulus”) of 3000 N/m 2 or less. Generally, the higher the elastic modulus of the 1st thermoplastic resin film 102, the tendency for a crack to generate|occur|produce easily. It is estimated that this is because, when the elastic modulus of the 1st thermoplastic resin film 102 is high, even if it is a case where the polarizer shrink|contracts, it is because there exists a tendency for stress to be hard to generate|occur|produce. However, according to the present invention, even when the elastic modulus of the first thermoplastic resin film 102 is 3000 N/m 2 or less, as described above, by lowering the shrinkage rate of the polarizer 101, the occurrence of cracks can be easily suppressed. can do. In this invention, the value in 23 degreeC is employable for an elastic modulus. The elastic modulus of the 1st thermoplastic resin film 102 is calculated|required by the measuring method demonstrated in the column of the Example mentioned later. The elastic modulus of the first thermoplastic resin film 102 is usually 1000 N/m 2 or more, for example, 1500 N/m 2 or more.

Examples of the first thermoplastic resin film 102 include polyolefin-based resins such as chain polyolefin-based resins (polypropylene-based resins, etc.) and cyclic polyolefin-based resins (norbornene-based resins, etc.); A transparent resin film containing a (meth)acrylic-type resin like polymethyl methacrylate-type resin, etc. is mentioned. Especially, from a viewpoint of optical light resistance and dimensional stability, Preferably it is a (meth)acrylic-type resin film or a cyclic polyolefin-type (COP) resin film. In particular, since the cyclic polyolefin-based (COP) resin film has a low modulus of elasticity, the polarizing plate of the present invention tends to be effective when the cyclic polyolefin-based (COP) resin film is used as the first thermoplastic resin film 102 . In general, since a film composed of a cyclic polyolefin-based resin has a low modulus of elasticity, a polarizing plate including this film tends to be prone to cracks around the mold release portion. However, according to the present invention, even if the first thermoplastic resin film 102 is a film made of such a cyclic polyolefin-based resin, it tends to be difficult to generate cracks around the release portion.

The thickness of the first thermoplastic resin film 102 is preferably thin from the viewpoint of reducing the thickness of the polarizing plate 100, but if it is too thin, the strength decreases and the workability tends to be inferior. Therefore, preferably 5 µm or more and 150 µm or less , more preferably 5 µm or more and 100 µm or less, still more preferably 10 µm or more and 50 µm or less.

The first thermoplastic resin film 102 may function as a protective film. In addition, either or both of the 1st thermoplastic resin film 102 and the 2nd thermoplastic resin film 103 mentioned later may be a protective film which has optical functions like retardation film and a brightness improvement film. For example, by stretching (uniaxial stretching or biaxial stretching, etc.) a transparent resin film made of the above material, or forming a liquid crystal layer or the like on the film, a retardation film to which an arbitrary retardation value is imparted can be obtained.

When the polarizing plate 100 is disposed in the image display device, the polarizing plate 100 can be bonded to the image display device such that the first thermoplastic resin film 102 is outside the image display device.

The first thermoplastic resin film 102 and the second thermoplastic resin film 103 to be described later may have a hard coat layer formed thereon. The hard-coat layer may be formed in one surface of a thermoplastic resin film, and may be formed in both surfaces. By providing a hard-coat layer, it can be set as the thermoplastic resin film which improved hardness and scratch property. The hard coat layer is, for example, a cured layer of an ultraviolet curable resin. Examples of the ultraviolet curable resin include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. The hard-coat layer may contain the additive in order to improve intensity|strength. The additive is not limited, and inorganic fine particles, organic fine particles, or a mixture thereof may be mentioned.

[Second Thermoplastic Resin Film]

The 2nd thermoplastic resin film 103 may be the same type as the film illustrated in description of the 1st thermoplastic resin film 102, or a different type may be sufficient as it. When the polarizing plate 100 is used for an image display device such that the second thermoplastic resin film 103 is disposed on the back side, the second thermoplastic resin film 103 may have an elastic modulus of 3000 N/m 2 or less, and the elastic modulus is A thing exceeding 3000 N/m<2> may be sufficient.

As the second thermoplastic resin film 103, a thermoplastic resin, for example, a polyolefin-based resin such as a chain polyolefin-based resin (polypropylene-based resin, etc.) or a cyclic polyolefin-based resin (norbornene-based resin or the like); Cellulose ester-based resins such as triacetyl cellulose or diacetyl cellulose; polyester-based resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate-based resin; (meth)acrylic resins such as polymethyl methacrylate-based resins; Or it may be a transparent resin film including a mixture or copolymer thereof.

The second thermoplastic resin film 103 may have a function as a protective film. When the polarizing plate 100 is arrange|positioned in an image display apparatus, the polarizing plate 100 can be bonded to an image display apparatus so that the 2nd thermoplastic resin film 103 may become an image display apparatus side.

[Other components of the polarizer]

(1) Optically functional film

The polarizing plate 100 may include an optically functional film other than the polarizer 101 for imparting a desired optical function, and a suitable example thereof is a retardation film.

As described above, although the first thermoplastic resin film 102 and/or the second thermoplastic resin film 103 may also serve as a retardation film, a retardation film may be laminated separately from these films. In the latter case, the retardation film may be laminated on the outer surface of the first thermoplastic resin film 102 and/or the second thermoplastic resin film 103 through an adhesive layer or an adhesive layer.

As retardation film, the birefringent film comprised from the stretched film of the thermoplastic resin which has translucency; a film in which a discotic liquid crystal or a nematic liquid crystal is aligned; Those in which the said liquid crystal layer was formed on the base film, etc. are mentioned.

A base film is a film containing a thermoplastic resin normally, and an example of a thermoplastic resin is cellulose ester-type resin, such as triacetyl cellulose.

Examples of other optically functional films (optical members) that may be included in the polarizing plate 100 include a light collecting plate, a brightness enhancing film, a reflective layer (reflective film), a transflective layer (semitransmissive reflective film), a light diffusing layer (light diffusing film), etc. am. These are generally provided in the case where the polarizing plate is a polarizing plate disposed on the back side (backlight side) of the liquid crystal cell.

(2) adhesive layer

The polarizing plate 100 can be set as a polarizing plate with an adhesive layer by providing an adhesive layer.

As an adhesive layer, the adhesive layer for bonding the polarizing plate 100 to image display elements, such as a liquid crystal cell and an organic electroluminescent display element, or another optical member is mentioned. The said adhesive layer can be laminated|stacked on the outer surface of the 2nd thermoplastic resin film 103 in the polarizing plate 100 of the structure shown in FIG.

As an adhesive used for an adhesive layer, what uses (meth)acrylic-type resin, silicone-type resin, polyester-type resin, polyurethane-type resin, polyether-type resin, etc. as a base polymer can be used. Among these, a (meth)acrylic adhesive is preferable from viewpoints, such as transparency, adhesive force, reliability, weather resistance, heat resistance, and rework property.

The (meth)acrylic pressure-sensitive adhesive includes (meth)acrylic acid alkyl ester having an alkyl group having 20 or less carbon atoms, such as a methyl group, an ethyl group, or an n-, i- or t-butyl group, (meth)acrylic acid or (meth)acrylic acid hydroxyethyl A (meth)acrylic resin having a weight average molecular weight of 100,000 or more, obtained by blending a functional group-containing (meth)acrylic monomer such as a glass transition temperature of preferably 25° C. or less, more preferably 0° C. or less, is used as a base polymer useful.

Formation of the pressure-sensitive adhesive layer on the polarizing plate is, for example, by dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare an adhesive solution, and directly coating this on the target surface of the polarizing plate to form the pressure-sensitive adhesive layer, release It can form by the system etc. which form an adhesive layer in sheet form on the separate film to which the process was given, and transfer it to the target surface of a polarizing plate.

Although the thickness of an adhesive layer is determined according to the adhesive force etc., the range of 1 micrometer or more and 50 micrometers or less is suitable, Preferably they are 2 micrometers or more and 40 micrometers or less.

The polarizing plate may include the above-described separate film. The separator film may be a film containing a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate. Especially, the stretched film of polyethylene terephthalate is preferable.

The pressure-sensitive adhesive layer may contain, if necessary, glass fibers, glass beads, resin beads, fillers containing metal powder or other inorganic powder, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents, and the like.

As an antistatic agent, although an ionic compound, electroconductive microparticles|fine-particles, a conductive polymer etc. are mentioned, For example, An ionic compound is used preferably.

The cation component constituting the ionic compound may be an inorganic cation or an organic cation.

Examples of the organic cations include pyridinium cations, imidazolium cations, ammonium cations, sulfonium cations, phosphonium cations, piperidinium cations, pyrrolidinium cations, and the like, and inorganic cations include lithium ions, potassium ions, etc. can be heard

On the other hand, the anion component constituting the ionic compound may be either an inorganic anion or an organic anion, but an anion component containing a fluorine atom is preferable in order to provide an ionic compound excellent in antistatic performance. Examples of the anion component containing a fluorine atom include hexafluorophosphate anion [(PF ₆ ^- )], bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N ^- ] anion, bis( and a fluorosulfonyl)imide anion [(FSO ₂ ) ₂ N ⁻ ] anion.

(3) protection film

The polarizing plate 100 may include a protection film for protecting the surface (typically, the surface of the first thermoplastic resin film 102 or the second thermoplastic resin film 103 ). After a polarizing plate is bonded to an image display element or another optical member, for example, a protection film peels and removes for every adhesive layer which it has.

The protection film is composed of, for example, a base film and an adhesive layer laminated thereon. Regarding the pressure-sensitive adhesive layer, the above-described technical content is cited.

The resin constituting the base film may be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate, or a thermoplastic resin such as a polycarbonate-based resin. . Preferably, it is polyester-type resin, such as a polyethylene terephthalate.

<Method for producing a polarizing plate>

The manufacturing method of the polarizing plate 100 is a process of preparing a polarizer, A preparation process including a 1st annealing process, A bonding process of bonding a polarizer and a 1st thermoplastic resin film, A 2nd annealing process, The outer edge of a polarizing plate It may include a mold release processing step of providing a concave portion in the portion or providing a through hole in the surface. In addition, the mold release processing process may be a process of providing both a recessed part and a through-hole in surface in the outer edge part of a polarizing plate.

When the polarizing plate 100 further includes the second thermoplastic resin film 103 , the manufacturing method includes a second bonding step of bonding the second thermoplastic resin film 103 to the other surface of the polarizer 101 . may include more.

[Preparation process]

The preparation process may include the process described about the manufacturing method of the above-mentioned polarizer. In the manufacturing method of the polarizing plate of the present invention, the preparation process may include a first annealing process.

[Joining process]

In a bonding process, a thermoplastic resin film can be respectively bonded (laminated) on both surfaces of the polarizer 101 via an adhesive agent. As the adhesive used for bonding the polarizer 101 and the thermoplastic resin film, an active energy ray-curable adhesive such as an ultraviolet curable adhesive, an aqueous solution of a polyvinyl alcohol-based resin or an aqueous solution in which a crosslinking agent is mixed therewith, and a water-based adhesive such as a urethane-based emulsion adhesive can be heard When bonding a thermoplastic resin film to both surfaces of the polarizer 101, the same type or different types may be sufficient as the adhesive agent which forms two adhesive bond layers. For example, when bonding a thermoplastic resin film to both surfaces, one side may be bonded using a water-based adhesive agent, and the other side may be bonded using an active energy ray-curable adhesive agent. The ultraviolet curing adhesive may be a mixture of a radically polymerizable (meth)acrylic compound and a photoradical polymerization initiator, a mixture of a cationically polymerizable epoxy compound and a photocationic polymerization initiator, or the like. Moreover, a cationically polymerizable epoxy compound and a radically polymerizable (meth)acrylic-type compound can be used together, and a photocationic polymerization initiator and a photoradical polymerization initiator can also be used together as an initiator.

When using an active energy ray-curable adhesive agent, after bonding, an adhesive agent is hardened by irradiating an active energy ray. Although the light source of the active energy ray is not particularly limited, an active energy ray (ultraviolet ray) having a light emission distribution at a wavelength of 400 nm or less is preferable, and specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light lamp , a microwave excited mercury lamp, a metal halide lamp, etc. are preferably used.

In order to improve the adhesiveness of the polarizer 101 and the thermoplastic resin film, prior to bonding the polarizer 101 and the thermoplastic resin film, the bonding surface of the polarizer 101 and/or the thermoplastic resin film is corona treated, flame treated, You may perform surface treatment, such as a plasma treatment, an ultraviolet irradiation treatment, a primer application process, and a saponification process.

Although the polarizing plate 100 of this invention can also be produced by bonding a thermoplastic resin film to the polarizer 101 which is a single-layer film as mentioned above, it is not limited to this method. For example, it can produce also by the method using a base film as described in Unexamined-Japanese-Patent No. 2009-98653. The latter method is advantageous for obtaining a polarizing plate having a thin polarizer (polarizer layer), and may include, for example, the following process.

A resin layer forming step of coating at least one surface of the base film with a coating solution containing a polyvinyl alcohol-based resin and then drying to form a polyvinyl alcohol-based resin layer to obtain a laminated film;

a stretching step of stretching a laminated film to obtain a stretched film;

A dyeing step of obtaining a light-polarizing laminated film by dyeing the polyvinyl alcohol-based resin layer of the stretched film with a dichroic dye to form a polarizer layer (corresponding to a polarizer);

The 1st bonding process which bonds a thermoplastic resin film using an adhesive agent on the polarizer layer of a light-polarizing laminated film, and obtains a bonding film,

A peeling process which peels and removes a base film from a bonding film, and obtains a polarizing plate with a single-sided thermoplastic resin film.

In the case of laminating the thermoplastic resin film on both sides of the polarizer 101 layer (polarizer), a second bonding step of bonding the second thermoplastic resin film to the polarizer side of the polarizing plate with the first thermoplastic resin film on one side using an adhesive is further performed. include

In the said method of using a base film, a drying process can be included in the dyeing process (for example, after the crosslinking process in the dyeing process of obtaining a light-polarizing laminated film, or after a washing process) of obtaining a light-polarizing laminated film. The polarizer contained in the said light-polarizing laminated film, the polarizing plate with a single-sided thermoplastic resin film, and the polarizing plate with a double-sided thermoplastic resin film obtained through the 2nd bonding process, or a polarizer isolated from these are also polarizers belonging to this invention.

[Release processing process]

The polarizing plate 100 can be obtained by cutting a long polarizing plate into a single-wafer shape to obtain a single-leaf polarizing plate, and forming a concave portion on the outer edge of the single-leaf polarizing plate or forming a through hole in the plane. Further, it is also possible to form both a concave portion and a through hole in the surface on the outer edge of the polarizing plate.

As a specific example of a method of forming a concave portion on the outer edge of a single-wafer polarizing plate or a method of forming a through hole in a plane, for example, a method of punching a single-wafered polarizing plate into an outer edge having a concave portion using a Thompson blade; , a method of cutting the end surface of the single-wafer polarizing plate using a router, and a method of performing drilling by using a rotary cutting mechanism such as a drill. When performing a mold release process, independent single-wafer type polarizing plate may be sufficient as it, and it is good also as a laminated body which stacked several sheets. The manufacturing method of the polarizing plate of this invention may include the 2nd annealing process of annealing to the long polarizing plate after a bonding process, whether it is a single-wafer polarizing plate, or the polarizing plate after mold-releasing this.

[Second annealing process]

The heating temperature in the second annealing process may be, for example, 65°C or more and 110°C or less, and preferably 70°C or more and 100°C or less. As for the heating temperature, there exists a tendency for a polarizer to become low-shrinkage with a higher one.

The heating time may be, for example, 3 hours or more and 96 hours or less, and preferably 12 hours or more and 72 hours or less. As for the heating time, there exists a tendency for a long one to make a polarizer low-shrink easily.

After the second annealing step, a step of forming a pressure-sensitive adhesive layer on the second thermoplastic resin film 103 side may be performed. As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, a (meth)acrylic pressure-sensitive adhesive, a styrene-based pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a polyester pressure-sensitive adhesive, an epoxy-based copolymer pressure-sensitive adhesive, and the like can be used.

<Image display device>

A polarizing plate can be used for an image display apparatus. As an image display element used for an image display apparatus, a liquid crystal display element, an organic electroluminescent display element, etc. are mentioned, for example. In constructing a liquid crystal display device, a polarizing plate may be used for the polarizing plate arrange|positioned at the visual recognition side, may be used for the polarizing plate arrange|positioned at the backlight side, and may be used for the polarizing plate of both the visual recognition side and the backlight side.

Example

Hereinafter, the present invention will be described in more detail using Examples, but the present invention is not limited to these Examples. In the examples, "%" and "parts" are mass % and parts by mass unless otherwise specified. The test and measurement were performed as follows.

[Measurement of contractile force]

The polarizing plate obtained in each Example and Comparative Example was cut into small pieces of 10 cm x 5 cm, immersed in 600 mL of a solvent, ultrasonicated for 30 minutes at room temperature, and the first and second thermoplastic resin films and second thermoplastic resins were bonded. The film was dissolved and removed.

Moreover, when both a 1st thermoplastic resin film and a 2nd thermoplastic resin film are the films (COP film) which consist of cyclic polyolefin resin, it melt|dissolved and removed using cyclohexane as a solvent.

When both the 1st thermoplastic resin film and the 2nd thermoplastic resin film were the films (TAC film) which consist of a triacetyl cellulose-type resin, it melt|dissolved and removed using methylene dichloride as a solvent.

When the first thermoplastic resin film is a COP film and the second thermoplastic resin film is a TAC film, or when the first thermoplastic resin film is a TAC film and the second thermoplastic resin film is a COP film, methylene dichloride is used as a solvent After dissolving and removing the TAC film using the cyclohexane solvent, the COP film was dissolved and removed to dissolve and remove the first thermoplastic resin film and the second thermoplastic resin film.

From the polarizing film from which the 1st thermoplastic resin film and the 2nd thermoplastic resin film were removed, the sample for MD contraction force measurement of width 2mm which makes an absorption axis direction (stretching direction) a long side, and length 10mm was cut out. This sample is set in a thermomechanical analysis device (TMA) "TMA7100" (manufactured by Hitachi High-Tech Sciences, Ltd.), and the long side direction (absorption axis direction) that occurs when the sample is kept at 80°C for 4 hours while keeping the dimensions constant. , MD) were measured.

[Measurement of modulus of elasticity]

A rectangular small piece having a long side of 110 mm x a short side of 10 mm was cut out from each thermoplastic resin film using a super cutter. Next, with the upper and lower clamps of a tensile tester [Autograph AG-Xplus tester manufactured by Shimadzu Corporation], the long sides of the sample for measurement were sandwiched so that the gap between the clamps was 5 cm, 23 °C, 55% relative humidity Under the environment, the sample for measurement is pulled in the longitudinal direction of the sample for measurement at a tensile rate of 4 mm/min, and from the slope of a straight line between 20 and 40 MPa in the obtained stress-strain curve, at 23° C. and 55% relative humidity The tensile modulus [MPa] of was calculated.

[thermal shock test]

The polarizing plates obtained in each Example and Comparative Example were bonded to the surface of an alkali-free glass (Eagle XG manufactured by Corning, 120 × 200 × 0.7 mm) which was well cleaned with ethanol, and then autoclaved at 50°C. did This was made into the sample for evaluation.

A sample for evaluation was put into a thermal shock test tank, and thermal stimulation of -40°C and 85°C was applied in cycles of 30 minutes each. The thermal stimulation from low temperature to high temperature was made into 1 cycle, and the test of a total of 400 cycles was done 50 cycles at a time about each sample.

[Crack Evaluation]

In the thermal shock test, the crack generation and growth of the evaluation sample were observed every 50 cycles using a loupe or an optical microscope. In particular, the periphery of the deformable part was observed in detail. For cracks, the occurrence position and length were measured, and when cracks of 0.3 mm or more occurred, the thermal shock test was stopped.

[Production of Polarizer]

The polarizing plate is a protective film [polyethylene (PE) film] / first thermoplastic resin film [diagonally stretched cyclic polyolefin-based resin (COP) film (ZD+HC film) having a hard coat layer), a thickness of 13 μm, an elastic modulus of about 2500 MPa]/polarizer [uniaxially stretched polyvinyl alcohol (PVA) film]/second thermoplastic resin film (COP film, thickness 13 µm, elastic modulus about 2000 MPa).

The polarizing plate is 1) in the manufacturing process of the polarizer, by raising the drying temperature to lower the shrinkage force in advance (preparation process), 2) cutting the produced polarizing plate into a sheet shape, and annealing treatment for some samples After reducing the shrinkage by using a processing/bonding step (processing step) of bonding the adhesive (for the image display panel), 3) a processing step of punching the polarizing plate sheet into a mold release shape and grinding the end portion (release processing step) ) was prepared by performing in this order.

1. Fabric making process

A polyvinyl alcohol film with an average degree of polymerization of about 2400, a saponification degree of 99.9 mol% or more and a thickness of 20 μm was immersed in pure water at 30° C. and iodine dyeing (hereinafter also referred to as iodine dyeing step). The polyvinyl alcohol film subjected to the iodine dyeing step was immersed in an aqueous solution having a mass ratio of potassium iodide:boric acid:water of 12:5:100 at 64°C to perform boric acid treatment (hereinafter also referred to as boric acid treatment step). The polyvinyl alcohol film that had been subjected to the boric acid treatment process was washed with pure water at 7° C. and dried at 85° C. to obtain a polarizer (thickness 8 μm after stretching) in which iodine was adsorbed to polyvinyl alcohol. At this time, it extended|stretched in the iodine dyeing process and the boric acid treatment process.

To the obtained polarizer, the hard-coated cycloolefin-type resin film (28 micrometers in thickness) was bonded together with the water-system adhesive agent, and the cellulose-type resin film (60 micrometers in thickness) was bonded together with the nip roll through water. After drying at 80° C. for 2 minutes while maintaining the tension of the resulting bonded product at 400 N/m, the cellulose-based resin film is delaminated, and the cycloolefin-based resin film (thickness of 13 μm) is bonded through an energy-curing adhesive, and UV By light-irradiating, the polarizing plate which has a protective film on both surfaces was obtained. A protective film provided with an adhesive on a PET substrate on the surface of the polarizing plate was bonded to the surface-treated surface of a surface-treated cycloolefin-based resin film to match the adhesive side of the PET substrate. A polarizing plate with a protection film was obtained.

2. Machining and joining process

The elongate polarizing plate produced in the fabric production process was cut out to a fixed size (250 mm x 330 mm). Both sides of the polarizing plate were sandwiched with dust-free paper, and the polarizing plate was clamped with an acrylic plate from the outside again. Prepare 3 sets of these, (1) 90 ° C., drying, 48 hours, (2) temperature 80 ° C., drying 48 hours, (3) standing or heating at 22 ° C., humidity 55%, polarizing plate (1), (2) and (3) were obtained. The samples of (2) and (3) were left still overnight after heating. The contractile forces of the polarizers in the polarizing plates (1), (2) and (3) were 0.59 N, 0.70 N, and 0.86 N, respectively.

The corona-treated surface of the 2nd thermoplastic resin film (panel side protective film) of the obtained polarizing plate was performed, and the adhesive film (with respect to an image display panel) was bonded together.

3. Partial processing

The completed polarizing plate sheet (250 x 330 mm) was punched out in the shape of the polarizing plate 300 shown in FIG. 8 using a Thomson blade, and this was laminated|stacked to the thickness of about 10 mm. The upper and lower sides of this polarizing plate bundle were sandwiched using one PS (polystyrene) sheet of the same shape punched out with a Thomson blade similarly, and 300 µm from the end was polished with a router to obtain a polarizing plate having the shape shown in FIG. . The radius of curvature of the rounding portions 302, 303 and 304 was 5.0 mm, 6.0 mm, and 4.0 mm, respectively, and the corner portion 305 was a right angle. The concave portion 301 had a width of 32.0 mm and a depth of 5.3 mm. The radii of curvature of the outer rounding portions 306 and 307 and the inner rounding portions 308 and 309 were 2.5 mm, 2.0 mm, 2.3 mm, and 2.5 mm, respectively. The concave portion 310 has a width of 5.0 mm and a depth of 7.3 mm, the radius of curvature of the rounding portion 311 is 2.5 mm, and the shortest distance 313 between the concave portion 301 and the center of gravity 312 of the polarizing plate is 64.7 mm. , the shortest distance 314 between the concave portion 310 and the center of gravity 312 of the polarizing plate was 62.7 mm.

<Examples 1 and 2, Comparative Example 1>

In Examples 1 and 2 and Comparative Example 1, each of the polarizing plates (1), (2) and (3) was subjected to a heating test using 5 sheets each, and light leakage was measured. The results are shown in Table 1 below.

As shown in Table 1, the polarizing plate by this invention did not generate|occur|produce a crack even after 150 cycle implementation in a thermal shock test.

10, 20, 40, 100, 300: Polarizing plate, 11, 12, 41, 301, 310: Concave portion, 302, 303, 304, 305: Corner, 13, 306, 307: Outer corner portion, 14, 15, 308 , 309, 311: inner corner portion, 312: center of gravity, 313, 314: shortest distance, 21: through hole, 42: long side, 43: midpoint, 101: polarizer, 102: first thermoplastic resin film, 103: second thermoplastic resin film

Claims (7)

A polarizer comprising a polyvinyl alcohol-based resin film, and a polarizing plate comprising a first thermoplastic resin film provided on one side thereof,
The polarizer has a contraction force per 2 mm in width in the absorption axis direction of 0.7 N or less,
The elastic modulus at 23° C. of the first thermoplastic resin film is 3000 N/m 2 or less,
The said polarizing plate has a concave part in an outer edge part, or has a through-hole in a plane in planar view, The polarizing plate. The polarizing plate according to claim 1, wherein the first thermoplastic resin film is an acrylic resin film or a cyclic polyolefin-based (COP) resin film. The polarizing plate according to claim 1 or 2, further comprising a second thermoplastic resin film provided on the other side of the polarizer. The polarizing plate with an adhesion layer which has the polarizing plate in any one of Claims 1-3, and the adhesive layer provided in the 1st thermoplastic resin film side of the said polarizing plate. The polarizing plate with an adhesive according to claim 4, wherein the pressure-sensitive adhesive layer is for bonding the polarizing plate to an image display element. The image display apparatus containing the polarizing plate in any one of Claims 1-3. As a manufacturing method of the polarizing plate in any one of Claims 1-3,
It is a process of preparing a polarizer, A preparation process including a 1st annealing process;
A bonding step of bonding the polarizer and the first thermoplastic resin film;
a second annealing process;
A mold release processing step of providing a concave portion on the outer edge of the polarizing plate or providing a through hole in the surface
A manufacturing method comprising a.

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