KR20220059947A - polarizer - Google Patents

Abstract

[Problem] A polarizer in which cracks are suppressed in a condensation heat shock test that repeats low-temperature (-40°C) condensation conditions and high-temperature (85°C) conditions, and where iodine loss occurs in the end region is not conspicuous to provide.
[Solution] A polarizer, which is a resin film containing boric acid and iodine, in a region including an end portion in plan view, a boric acid low concentration region having a lower boric acid concentration than that in an inner region 500 µm or more inside from the end portion is formed, and a low iodine concentration region having an iodine concentration lower than that in the inner region is formed in the region including the end portion, and the length of the low iodine concentration region from the end portion of the polarizer is 19 μm or more and 100 μm or less.
[Selectivity] None

Description

polarizer

The present invention relates to a polarizer, and also to a polarizing plate provided with the same, a manufacturing method thereof, and an image display device.

The light polarizer in which the site|part in which the content density|concentration of boric acid was lower than the other site|part was formed in the edge part is proposed by patent document 1.

Patent Document 1: Japanese Patent Laid-Open No. 2016-206641

In the light polarizer described in Patent Document 1, in addition to having a portion having a low boric acid concentration formed at the end, iodine loss is occurring in a width exceeding 300 µm from the end portion in plan view (Fig. 4(b)).

An object of the present invention is to expose to low-temperature (-40°C) drying conditions to cool, then expose to 25°C outdoor air to form a state of dew condensation, and then repeat the operation of exposing under high-temperature (85°C) drying to dew condensation heat shock It is to provide a polarizer in which cracks are suppressed in the test and the site in which iodine loss has occurred in the end region is not conspicuous, a polarizing plate provided with the same, and a manufacturing method thereof.

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

[1] A polarizer that is a resin film containing boric acid and iodine,

In the region including the end portion in plan view, a boric acid low concentration region having a concentration of boric acid lower than that in the inner region 500 μm or more inside from the end portion is formed;

In the region including the end portion, a low iodine concentration region having a lower iodine concentration than that in the inner region is formed,

A polarizer having a length of 19 μm or more and 100 μm or less from the end of the low iodine concentration region.

[2] The polarizer according to [1], wherein the concentration of boric acid at the low boric acid concentration site becomes lower as it approaches the end portion in a direction from the inner side to the end portion in a planar view of the polarizer.

[3] The polarizer according to [1] or [2], wherein the length from the end of the low boric acid concentration site is 15 µm or more.

[4] The polarizer according to any one of [1] to [3], wherein the boric acid low concentration portion and the iodine low concentration portion are formed along an outer edge of the polarizer.

[5] In any one of [1] to [4], wherein the polarizer has a deformable portion in plan view, and in which the boric acid low concentration site and the low iodine concentration site are formed in the end region included in the deformable portion described polarizer.

[6] The polarizer according to [5], wherein the deformable portion is a concave portion formed on the periphery or a through hole formed in the surface of the polarizer.

[7] A polarizing plate comprising the polarizer according to any one of [1] to [6], and an optical film disposed on one or both sides of the polarizer.

[8] The image display device provided with the polarizing plate as described in [7].

[9] The image display device according to [8], having a camera hole.

[10] A method for producing a polarizing plate comprising: a polarizer that is a resin film containing boric acid and iodine; and an optical film disposed on one or both sides of the polarizer;

A method for producing a polarizing plate comprising a base treatment step of contacting an end of the resin film containing boric acid and iodine with a basic solution having a temperature of 50° C. or less in 6 minutes or less.

[11] The method for producing a polarizing plate according to [10], wherein the basic solution contains water.

[12] The method for producing a polarizing plate according to [10] or [11], wherein the basic solution is a solution in which a strong basic compound is dissolved in a solvent.

[13] The method for producing a polarizing plate according to [12], wherein the strongly basic compound contains sodium hydroxide and/or potassium hydroxide.

[14] Further comprising a molding step of molding the resin film containing boric acid and iodine into a predetermined shape by cutting and/or punching processing, wherein the resin film after the molding step is subjected to the base treatment step The manufacturing method of the polarizing plate in any one of [10]-[13].

According to the present invention, after exposure to low temperature (-40°C) drying conditions and cooling, it is exposed to outside air at 25°C to form a state of dew condensation, followed by repeated exposure under high temperature (85°C) drying. A polarizer in which cracks are suppressed in (hereinafter also referred to simply as a condensation heat shock test for simplicity) and in which an iodine loss occurs in an end region is not conspicuous, a polarizing plate having the same, and manufacturing thereof method can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows the polarizer by one Embodiment of this invention.
2 is a schematic top view of a polarizer for explaining a boric acid low concentration site.
3 is a schematic top view of a polarizer for explaining a low iodine concentration site.
4 is a schematic cross-sectional view showing an example of an image display device having a camera hole.
It is a schematic top view which shows the polarizer by one Embodiment of this invention.
6 is a schematic plan view showing a polarizing plate according to an embodiment of the present invention.
7 is a schematic plan view showing a polarizing plate according to an embodiment of the present invention.
It is a schematic plan view which shows the polarizing plate by one Embodiment of this invention.
It is a schematic sectional drawing which shows the polarizing plate by one Embodiment of this invention.
It is a schematic diagram which shows an example of a 1st laminated body.
It is a schematic diagram which shows an example of a 2nd laminated body and an end mill.
12 is a schematic diagram illustrating an example of a cutting process.
It is a schematic diagram for demonstrating the measurement sample in an Example.
It is a schematic sectional drawing which shows the 1st laminated body in an Example.
It is a schematic top view which shows the polarizing plate in an Example.
16 shows the TOF-SIMS analysis result and the end observation result of Example 1. FIG.
17 shows a result of TOF-SIMS analysis and an end observation result of Comparative Example 1.
18 shows a result of TOF-SIMS analysis and an end observation result of Comparative Example 2.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described, referring drawings, this invention is not limited to the following embodiment. In all the drawings below, the scales are appropriately adjusted for easy understanding of each component, and the scale of each component shown in the drawings does not necessarily coincide with the scale of the actual component. In the drawings, equal reference numerals are given to equal components. X, Y, and Z shown in each figure mean three coordinate axes orthogonal to each other. The directions indicated by each of the XYZ coordinate axes in each figure are common to each figure.

<Polarizer>

A polarizer is a resin film containing boric acid and an iodine. The resin film containing boric acid and iodine may be, for example, a resin film in which iodine is oriented by adsorption to a uniaxially stretched polyvinyl alcohol-based resin film, and polyvinyl alcohol molecular chains are crosslinked with boric acid. The polarizer 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). A polarizer can be used as a polarizing plate by bonding an optical film to one or both sides with an adhesive agent, an adhesive, etc.

As shown in FIG. 1 , the polarizer 2 can comprise the polarizing plate 1 by being arrange|positioned between the 1st optical film 3 and the 2nd optical film 4 . Hereinafter, a 1st optical film and a 2nd optical film may be generically called an optical film.

In the polarizer, in the region including the end portion in plan view, a boric acid low concentration region having a lower boric acid concentration than the boric acid concentration in the inner region (hereinafter also referred to as an inner region) 500 μm or more inside the end portion is formed. . In the inner region, both the concentration of boric acid and the concentration of iodine may be approximately equal. As shown in Fig. 2, the polarizer 2 has a low boric acid concentration region 30 in a region including the end portion in plan view, and may have an inner region 32 inside 500 μm or more from the end portion. . The inner region 32 may include a region for displaying an image when inserted into the liquid crystal display device. The boric acid concentration in the intermediate region 31 between the boric acid low concentration region 30 and the inner region 32 is usually substantially the same as that of the inner region 32 . As used herein, planar view means viewing in the thickness direction of the polarizer. The concentration of boric acid refers to the concentration of boric acid per unit area including the thickness direction of the polarizer, and is measured by, for example, time-of-flight secondary ion mass spectrometry (TOF-SIMS) described in the Examples below. In the present specification, boric acid includes, for example, a boric acid molecule (H ₃ BO ₃ ) and a boric acid ion (BO ₃ ^3- ).

In a polarizer, generation|occurrence|production of a crack tends to become easy to be suppressed in a dew condensation heat shock test by the boric-acid low concentration site|part being formed. The condensation heat shock test can be performed according to the method described in the column of Examples to be described later.

The concentration of boric acid in the boric acid low concentration site is preferably at the end in the direction from the inside to the end in a planar view of the polarizer from the viewpoint of suppressing cracks and making color loss less conspicuous in the appearance of the polarizer. The closer it was, the lower it was. The ends of the polarizer preferably do not contain boric acid.

The length from the end of the boric acid low concentration site may be, for example, 15 µm or more, and from the viewpoint of crack suppression, preferably 15 µm or more and less than 200 µm, more preferably 15 µm or more and less than 150 µm, still more preferably 15 µm or more. It may be less than 100 μm, particularly preferably more than 15 μm and less than 50 μm.

The boundary between the region in which the boric acid low concentration region is formed and the region other than it can be obtained from the boric acid concentration profile with respect to the distance from the end obtained by the time-of-flight secondary ion mass spectrometry (TOF-SIMS) described in the section of Examples to be described later. there is. For example, when a region with a constant boric acid ion strength is read in the boric acid concentration profile, the average value of the boric acid ion strength of the region is obtained, and the region from the end to the position where the boric acid ion strength becomes the average value can be defined as the low boric acid concentration region. . If the region where the boric acid ion strength is constant is difficult to read in the boric acid concentration profile, in the boric acid concentration profile, the average value of the boric acid ion strength in the range of 30 μm is obtained from the point at which the boric acid ion strength is the maximum, The position from the edge part to the position where boric acid ion intensity|strength becomes the said average value can be made into a boric-acid low concentration site|part.

In the polarizer, a low iodine concentration site having a lower iodine concentration than the iodine concentration in the inner region 500 µm or more inside the polarizer is formed in a region including the end portion. The length from the end of the low iodine concentration site is 19 µm or more and 100 µm or less. As shown in FIG. 3, the polarizer 2 has the low iodine concentration site|part 33 in the area|region including the edge part in planar view. The iodine concentration of the intermediate region 34 between the low iodine concentration region 33 and the inner region 32 is usually approximately the same as that of the inner region 32 . An iodine low concentration site|part is a site|part formed in the area|region through which light transmits in planar observation of the polarizer using the optical microscope. Iodine includes, for example, an iodine molecule (I ₂ ), a polyiodine complex (I ₃ ⁻ , I ₅ ⁻ ), and an iodine ion (I ⁻ ).

When the length from the end of the low iodine concentration portion is 100 μm or less, the low iodine concentration portion tends to be difficult to be conspicuous in the external appearance of the polarizer. Moreover, when the length from the edge part of a low iodine concentration site|part is 19 micrometers or more, there exists a tendency for a crack to be suppressed easily. The length from the end of the low iodine concentration site is preferably 19 µm or more and 50 µm or less from the viewpoint of making the loss of iodine less conspicuous.

A site with a low iodine concentration and a site with a high iodine concentration are discriminated according to the method described in the section of Examples to be described later. In an optical microscope image captured and image-processed on a personal computer, the brightness of the low iodine concentration region is usually 180 or more, and the inner region is 100 or more and 140 or less, and an intermediate region between the low iodine concentration region and the inner region. The brightness of the iodine concentration is usually less than 180.

The boric acid low concentration site and the low iodine concentration site may be a site partially overlapping with each other, or one may be a site completely overlapping the other. From the viewpoint of suppressing cracks and making iodine loss less conspicuous, preferably, the low iodine concentration site completely includes the boric acid low concentration site.

The boric acid low concentration site|part and the iodine low concentration site|part may each be formed in plurality in the some area|region of a polarizer.

The boric acid low concentration site|part and the low iodine concentration site|part are preferably formed along the outer edge of a polarizer from a viewpoint of crack suppression. The boric acid low concentration site|part and the iodine low concentration site|part may be formed along the whole outer edge part of a polarizer, and may be formed along a part of the outer edge part of a polarizer.

The polarizer may have a deformable part. The release portion may be a concave portion formed on the outer edge portion of the polarizer in plan view, and a through hole formed in the surface of the polarizer. Moreover, the direction of the tangent line is discontinuous, for example, the shape of two straight lines intersecting the deformed part may be 0 mm at the intersection of the radius of curvature. The effect of preventing cracks according to the present invention when the direction of the tangent line is discontinuous or when the radius of curvature at the intersection is small (usually 3 mm or less, preferably 2 mm or less, more preferably 1 mm or less) is conspicuous The polarizer may have two or more deformable parts in an outer edge part and/or in-plane. As for the specific example of the shape and formation position of a mold part, the example of the shape and formation position of the mold part in the description of a polarizing plate mentioned later is applied.

When the polarizer has a release portion, cracks are suppressed and the low iodine concentration portion is preferably formed in the end region included in the mold release portion from the viewpoint of suppressing cracks and forming the low iodine concentration portion and the boric acid low concentration portion.

The polarizer which has a mold release part is a dew condensation heat shock test. WHEREIN: Stress tends to concentrate in a mold part part, and there exists a tendency for a crack to generate|occur|produce easily. When a boric-acid low concentration site|part is formed in the edge part area|region contained in a mold release part, there exists a tendency for generation|occurrence|production of a crack to become easy to suppress in a dew condensation heat shock test.

Moreover, as shown in FIG. 4, the polarizing plate 21 provided with the polarizer which has a mold release part, the camera hole 22, the cover glass 24, the adhesive layer 25, the liquid crystal panel 23, the polarizing plate 26 ), the camera 27 and the light-shielding tape 28 when used in the image display device 20, in Fig. 4, the portion enclosed in the circle is directly visible, so included in the release portion of the polarizer 21 The low iodine concentration site|part formed in a wide area|region in an edge part becomes conspicuous, and as a result, the fall of design may be caused. However, even if it is a case where the polarizer of this invention is used for the image display apparatus which has the above camera holes, a site|part with a low iodine concentration is hard to be conspicuous, and it exists in the tendency excellent in design.

When the deformable portion is a concave portion, it is preferably formed so that the depth direction of the concave portion and the absorption axis (stretching direction) are orthogonal to each other from the viewpoint of crack suppression, for example. Moreover, you may form so that it may intersect at an angle of 30 degrees or more and usually 60 degrees or less.

A long strip|belt shape may be sufficient as a polarizer, and single-wafer type may be sufficient as it. When the polarizer is a single-wafer type, the polarizer may have a square shape or a rounded square shape in plan view. The 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 rounded, and the rectangle refers to a shape in which all four corners are not rounded. 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 polarizer may have a polygonal, circular, or elliptical overall shape in plan view. The example of the overall shape of a polarizing plate in description of the polarizing plate mentioned later is applied to the specific example of the overall shape in planar view of a polarizer.

The thickness of the polarizer may be, for example, 1 µm or more and 50 µm or less, or 3 µm or more and 15 µm or less. As the polarizer is thinner, the shrinkage or expansion of the polarizer itself with a change in temperature tends to be suppressed, and the change in the dimension of the polarizer itself tends to be suppressed. As a result, stress becomes difficult to act on a polarizer, and there exists a tendency for the crack in a polarizer to become suppressed easily.

FIG. 5 shows the overall shape of the polarizer 2 in a plan view. The polarizer 2 is a quadrangle in which the overall shape was rounded, and has a concave part as a deformable part. The concave portion is formed so that the depth direction and the absorption axis (stretching direction) are parallel to each other. In the polarizer 2, the region I11 and the region II12 are partially formed along a part of the outer periphery including the concave portion, and are formed in the outer edge portion including the concave portion. Region I (11) is a region in which both a boric acid low concentration site and a low iodine concentration site are formed. Region II (12) may be a region in which either a boric acid low concentration site or a low iodine concentration site is formed.

<Polarizer>

The polarizing plate which concerns on another aspect of this invention is a polarizing plate containing the above-mentioned polarizer and the optical film formed in the one or both sides. The optical film may be bonded to the polarizer through an adhesive layer made of an adhesive or pressure-sensitive adhesive.

As shown in FIG. 1 , the polarizing plate 1 according to the present embodiment is a film-type polarizer 2 positioned between at least a pair of optical films 3 and 4 and a pair of optical films 3 and 4 . ) is provided. Hereinafter, for convenience of explanation, the polarizing plate 1 composed of the polarizer 2 and a pair of optical films 3 and 4 is mainly described. However, as will be described later, the number of optical films included in the polarizing plate is not limited to two.

An optical film means the film-shaped member (excluding the polarizer 2 itself) which comprises the polarizing plate 1. For example, an optical film includes a protective film and a release film. Each optical film alone may not have a specific optical function. A "film" (optical film) may be in other words a "layer" (optical layer). Each of the pair of optical films 3 and 4 contains a resin. However, the composition of each of the optical films 3 and 4 is not limited.

The polarizer 2 overlaps with each of the optical films 3 and 4 directly or indirectly. For example, there may be a separate optical film between the polarizer 2 and the optical films 3 and 4 . The polarizer 2 may overlap with each of the optical films 3 and 4 via an adhesive layer.

6 : is a top view which shows the surface of the polarizing plate 1 which concerns on this embodiment. The cross section of the polarizing plate 1 shown in FIG. 6 is perpendicular to the surface of the polarizing plate 1 . Moreover, the cross section of this polarizing plate 1 is orthogonal to the outer periphery 1p of the polarizing plate 1 located inside the recessed part 13 formed in the polarizing plate 1 .

As shown in FIG. 6 , a concave portion 13 is formed on the outer periphery 1p of the polarizing plate 1 . That is, there is a concave portion 13 on the outer periphery 1p of the polarizing plate 1 . The concave portion 13 may be in other words a depression, a cutout, or a notch. The recessed portion 13 can penetrate the polarizing plate 1 in a direction (Z-axis direction) perpendicular to the surface (light-receiving surface) of the polarizing plate 1 . The outer periphery 1p of the polarizing plate 1 may be in other words an outer periphery or outline of the polarizing plate 1 (light-receiving surface) viewed in a direction (planar view direction) perpendicular to the light-receiving surface of the polarizing plate 1 .

The corner 13c inside the recessed part 13 may be a right angle in a top view, and may be made into a curve. That is, the end surface of the polarizing plate 1 positioned at the inner corner 13c of the concave portion 13 may be curved. That is, the corner 13c on the inner side of the concave portion may be chamfered. Because the corner 13c inside the recess 13 is curved in a top view, cracks are easily suppressed at the corner 13c inside the recess 13 as compared to the case where it is a right angle. As shown in FIG. 4 , corner portions positioned at both ends of the concave portion 13 and corner portions positioned at four corners of the polarizing plate 1 may also be chamfered.

The width of the concave portion 13 (the width of the concave portion 13 in the X-axis direction) is not particularly limited, but may be, for example, 3 mm or more and 160 mm or less. The depth of the concave portion 13 (the width of the concave portion 13 in the Y-axis direction) is not particularly limited, but may be, for example, 0.5 mm or more and 160 mm or less. Although the length of the side (short side) of the polarizing plate 1 in which the recessed part 13 is formed is not specifically limited, For example, it may be 30 mm or more and 90 mm or less. The length of the side (longer side) of the polarizing plate 1 on which the concave portion 13 is not formed is not particularly limited, but may be, for example, 30 mm or more and 170 mm or less.

Although the thickness of the whole polarizing plate 1 is not specifically limited, For example, it may be 30 micrometers or more and 300 micrometers or less.

The concave portion 13 shown in Fig. 6 is a rounded rectangle (rectangle). However, the shape of the concave portion 13 is not limited. For example, the concave portion 13 may have a square shape. The concave portion 13 may be a polygon other than a square and a triangle. As shown in (a) to (h) of FIG. 7 , the shape of the concave portion 13 may be a rounded rectangle, a rectangle, a semicircle, a V-shape, a shape in which a straight line and a curved line are combined, or a curved shape. Although the shape of the polarizing plate 1 shown to (a)-(h) in FIG. 7 all has symmetry, the shape of the polarizing plate 1 may be asymmetrical. A plurality of concave portions 13 may be formed in the outer periphery 1p of the polarizing plate 1 . The plurality of concave portions 13 may be formed on one side constituting the outer periphery 1p of the polarizing plate 1 . The concave portion 13 may be formed by cutting off at least one of the four corners of the rectangular polarizing plate 1 .

The overall shape of the polarizing plate 1 excluding the concave portion 13 is substantially rectangular (rectangular). However, the shape of the polarizing plate 1 is not limited. For example, the shape of the polarizing plate 1 may be a square. The shape of the polarizing plate 1 may be polygons other than a quadrangle, a circle, or an ellipse. The overall shape of each of the polarizer 2 and the optical films 3 and 4 may be approximately the same as the shape of the polarizing plate 1 . In the case of the rectangular polarizing plate 1 shown in FIG. 4 , the concave portion 13 is formed on the short side of the polarizing plate 1 , but the concave portion 13 may be formed on the long side of the polarizing plate 1 . .

As shown in FIG. 8, the polarizer 1 may have a through-hole in plane in planar view. The diameter of the through hole 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.

(Another embodiment of a polarizing plate)

For example, the polarizing plate may further include a separate optical film including a resin in addition to a pair of optical films consisting of the first optical film and the second optical film. That is, a polarizing plate can be equipped with 3 or more optical films. For example, as shown in FIG. 9 , the polarizing plate is positioned between the first optical film 3 and the second optical film 4 , and the first optical film 3 and the second optical film 4 . The polarizer 2 and the 3rd optical film 15 overlapping with the 1st optical film 3 can be provided. The third optical film 15 may be overlapped with the first optical film 3 through the above-described adhesive layer. The resin included in the third optical film 15 may be at least any one of the above resins listed as the resin included in each of the first optical film 3 and the second optical film 4 . The composition of the third optical film 15 may be the same as that of the first optical film 3 . The composition of the third optical film 15 may be different from that of the first optical film 3 . The composition of the third optical film 15 may be the same as that of the second optical film 4 . The composition of the 3rd optical film 15 may differ from the composition of the 2nd optical film 4 . The thickness of the third optical film 15 may be, for example, 5 μm or more and 200 μm or less. The third optical film 15 may be peeled off and removed from the polarizing plate during the manufacturing process of the image display device. That is, the third optical film 15 may be a temporary optical film.

The polarizing plate may further include a pressure-sensitive adhesive layer overlapping one of the pair of optical films, and a release film overlapping the pressure-sensitive adhesive layer. For example, the polarizing plate shown in FIG. 9 may further include a pressure-sensitive adhesive layer overlapping the second optical film 4 and a release film overlapping the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer may include, for example, a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, or a urethane pressure-sensitive adhesive. The thickness of the adhesive layer may be, for example, 2 μm or more and 100 μm or less. The resin included in the release film may be at least any one of the resins listed as resins included in each of the first optical film 3 and the second optical film 4 . The composition of the release film may be the same as that of the first optical film 3 . The composition of the release film may be different from the composition of the first optical film 3 . The composition of the release film may be the same as that of the second optical film 4 . The composition of the release film may be different from the composition of the second optical film 4 . The thickness of the release film may be, for example, 10 μm or more and 100 μm or less. The release film may be peeled off and removed from the polarizing plate in the manufacturing process of the image display device. A release film may be arrange|positioned on both surfaces of a polarizing plate through an adhesion layer.

A polarizing plate, as an optical film or layer, is a reflective polarizing film, a film with an anti-glare function, a film with a surface antireflection function, a reflective film, a transflective film, a viewing angle compensation film, a window film, an antistatic layer, a hard coat layer, At least one selected from the group consisting of an optical compensation layer, a touch sensor layer, and an antifouling layer may be further provided.

A polarizing plate can have a mold release part in planar view. In addition, the polarizing plate may be a quadrangle or a rounded quadrangle in plan view.

(optical film)

The optical film may be a thermoplastic resin having transparency. The optical film may be an optically transparent thermoplastic resin. The resin constituting the optical film is, for example, a chain polyolefin-based resin, a cyclic olefin polymer-based resin (COP-based resin), a cellulose ester-based resin, a polyester-based resin, a polycarbonate-based resin, a (meth)acrylic resin, and a polystyrene-based resin. resin, or a mixture or copolymer thereof.

When the polarizing plate has the first optical film and the second optical film, the composition of the first optical film may be exactly the same as that of the second optical film. For example, both the first optical film and the second optical film may include a cyclic olefin polymer-based resin (COP-based resin). Even when the first optical film and the second optical film contain a cyclic olefin polymer-based resin (COP-based resin), cracks are easily suppressed in the present invention, and color loss tends to become inconspicuous. When a polarizing plate has a 1st optical film and a 2nd optical film, the composition of a 1st optical film may differ from a composition of a 2nd optical film.

It is preferable that the glass transition temperatures of a 1st optical film and a 2nd optical film are 100 degrees C or more and 200 degrees C or less, or 120 degrees C or more and 150 degrees C or less. When the glass transition temperature of each of the first optical film and the second optical film is within the above range, the first optical film and the second optical film are likely to be fused to each other by heat generated by polishing of the end of each optical film.

The chain-type polyolefin-based resin may be, for example, a homopolymer of a chain-type olefin such as a polyethylene resin or a polypropylene resin. The chain polyolefin resin may be a copolymer composed of two or more chain olefins.

The cyclic olefin polymer-based resin (cyclic polyolefin-based resin) may be, for example, a ring-opened (co)polymer of a cyclic olefin or an addition polymer of a cyclic olefin. The cyclic olefin polymer-based resin may be, for example, a copolymer (eg, a random copolymer) of a cyclic olefin and a chain olefin. The chain olefin constituting the copolymer may be, for example, ethylene or propylene. The cyclic olefin polymer resin may be a graft polymer obtained by modifying the polymer with an unsaturated carboxylic acid or a derivative thereof, or a hydride thereof. The cyclic olefin polymer-based resin may be, for example, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer.

The cellulose ester-based resin may be, for example, cellulose triacetate (triacetyl cellulose (TAC)), cellulose diacetate, cellulose tripropionate or cellulose dipropionate. You may use these copolymers. You may use the cellulose ester-type resin by which a part of hydroxyl group was modified by the other substituent.

You may use polyester-type resin other than cellulose-ester-type resin. The polyester-based resin may be, for example, a polycondensate of a polyhydric carboxylic acid or a derivative thereof and a polyhydric alcohol. Polyhydric carboxylic acid or its derivative(s) may be dicarboxylic acid or its derivative(s). The polyhydric carboxylic acid or its derivative may be, for example, terephthalic acid, isophthalic acid, dimethyl terephthalate, or dimethyl naphthalenedicarboxylic acid. The polyhydric alcohol may be, for example, a diol. The polyhydric alcohol may be, for example, ethylene glycol, propanediol, butanediol, neopentyl glycol or cyclohexanedimethanol.

The polyester-based resin is, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate, or polycyclohexane. It may be dimethyl naphthalate.

The polycarbonate-based resin is a polymer in which a polymerization unit (monomer) is bonded through a carbonate. The polycarbonate-based resin may be a modified polycarbonate having a modified polymer skeleton, or may be a copolymerized polycarbonate.

The (meth)acrylic resin is, for example, poly(meth)acrylic acid ester (eg, polymethyl methacrylate (PMMA)); methyl methacrylate-(meth)acrylic acid copolymer; methyl methacrylate-(meth)acrylic acid ester copolymer; methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymer; (meth) methyl acrylate-styrene copolymer (eg, MS resin); It may be a copolymer of methyl methacrylate and a compound having an alicyclic hydrocarbon group (eg, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-(meth) acrylate norbornyl copolymer, etc.).

Each of the first optical film or the second optical film may include at least one additive selected from the group consisting of a lubricant, a plasticizer, a dispersant, a heat stabilizer, an ultraviolet absorber, an infrared absorber, an antistatic agent, and an antioxidant.

The thickness of the first optical film may be, for example, 5 μm or more and 90 μm or less, or 10 μm or more and 60 μm or less. The thickness of the second optical film may also be, for example, 5 μm or more and 90 μm or less, or 10 μm or more and 60 μm or less.

At least one of the first optical film and the second optical film may be a film having an optical function. The film having an optical function may be, for example, a retardation film or a brightness enhancing film. For example, the retardation film to which arbitrary retardation values were provided is obtained by extending|stretching the film which consists of the said thermoplastic resin, or forming a liquid-crystal layer etc. on the film.

The first optical film may overlap the polarizer through an adhesive layer. The second optical film may also be overlapped with the polarizer through the adhesive layer. The adhesive layer may include a water-based adhesive such as polyvinyl alcohol. The adhesive layer may also contain the active energy ray-curable resin mentioned later.

Active energy ray-curable resin is resin which hardens|cures when an active energy ray is irradiated. The active energy ray may be, for example, ultraviolet light, visible light, electron beam or X-ray. For example, the active energy ray-curable resin may be an ultraviolet-curable resin.

Active energy ray-curable resin may be 1 type of resin, and may also contain multiple types of resin. For example, active energy ray-curable resin can contain a cationically polymerizable sclerosing|hardenable compound, or a radically polymerizable sclerosing|hardenable compound. The active energy ray-curable resin may include a cationic polymerization initiator or a radical polymerization initiator for initiating a curing reaction of the curable compound.

The cationically polymerizable curable compound may be, for example, an epoxy-based compound (a compound having at least one epoxy group in its molecule) or an oxetane-based compound (a compound having at least one oxetane ring in its molecule). The radical polymerizable curable compound may be, for example, a (meth)acrylic compound (a compound having at least one (meth)acryloyloxy group in the molecule). The radically polymerizable sclerosing|hardenable compound may be a vinyl-type compound which has a radically polymerizable double bond.

The active energy ray-curable resin may optionally contain a cationic polymerization accelerator, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, an antifoaming agent, an antistatic agent, a leveling agent or a solvent. may include

In order to improve the adhesiveness of a polarizer and an optical film, prior to bonding of a polarizer and an optical film, on the bonding surface of a polarizer and/or an optical film, corona treatment, flame treatment, plasma treatment, ultraviolet irradiation treatment, primer coating treatment, saponification You may perform surface treatment, such as a treatment.

(Other floors)

A polarizing plate is a front plate, a retardation film (for example, a layer imparting a retardation of λ/2, a layer imparting a retardation of λ/4, a positive C layer, a layer obtained by laminating a combination of at least two layers selected from these, etc. ), a protection film, a touch sensor panel, an adhesive layer, etc. may be further provided. A polarizing plate can also be used as a circularly polarizing plate by laminating|stacking the layer which provides the phase difference of (lambda)/4. A polarizing plate with an adhesive layer may be sufficient as a polarizing plate.

<Method for producing a polarizing plate>

The manufacturing method of a polarizing plate is a manufacturing method of a polarizing plate which has a polarizer which is a resin film containing boric acid and iodine, and the optical film arrange|positioned on one or both sides of this polarizer, At the edge part of the resin film containing boric acid and iodine, 50 It is a manufacturing method comprising a base treatment step of contacting a basic solution having a temperature of ℃ or less in 6 minutes or less. The manufacturing method of this polarizing plate may further include the polarizer manufacturing process mentioned later (manufacturing process of a resin film containing boric acid and iodine), a lamination process, a shaping|molding process, and a cutting process in this order before this base treatment process. .

(Polarizer manufacturing process)

A resin film containing boric acid and iodine (hereinafter also referred to as a light base treated polarizer) can be produced, for example, by subjecting a polyvinyl alcohol-based resin film (PVA film) to a stretching treatment, a dyeing treatment, and a crosslinking treatment. The stretching treatment, the dyeing treatment and the crosslinking treatment can be performed by a known method.

For example, first, a PVA film is stretched in a uniaxial direction or a biaxial direction. The dichroic ratio of the polarizer stretched in the uniaxial direction tends to be high. After stretching, the PVA film is dyed with iodine, a dichroic dye (polyiodine) or an organic dye using a dyeing solution. The dyeing solution may contain boric acid, zinc sulfate, or zinc chloride. You may wash the PVA film with water before dyeing. By washing with water, stains and antiblocking agents are removed from the surface of the PVA film. Moreover, as a result of the swelling of a PVA film by water washing, it is easy to suppress the unevenness of dyeing (non-uniform dyeing|dyeing). The PVA film after dyeing is treated with a solution of a crosslinking agent containing boric acid (eg, an aqueous solution of boric acid) for crosslinking. After treatment with the crosslinking agent, the PVA film is washed with water and then dried. Through the above procedures, a resin film containing boric acid and iodine is obtained.

Polyvinyl alcohol (PVA)-type resin is obtained by saponifying polyvinyl acetate-type resin. The polyvinyl acetate-based resin may be, for example, polyvinyl acetate, which is a homopolymer of vinyl acetate, or a copolymer of vinyl acetate and other monomers (eg, ethylene-vinyl acetate copolymer). Other monomers copolymerized with vinyl acetate may be unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, or acrylamides having an ammonium group in addition to ethylene. The polyvinyl alcohol-based resin may be modified with aldehydes. The modified polyvinyl alcohol-based resin may be, for example, partially formalized polyvinyl alcohol, polyvinyl acetal or polyvinyl butyral. The polyvinyl alcohol-based resin may be a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride. You may dye|stain before extending|stretching, and you may extend|stretch in a dyeing solution. The length of the stretched resin film may be, for example, 3 to 7 times the length before stretching. A long strip|belt shape may be sufficient as a polyvinyl alcohol-type resin film, and single-wafer type may be sufficient as it.

(Lamination process)

At a lamination|stacking process, a 1st laminated body is produced by overlapping a slight base treatment polarizer and an optical film and bonding together. The light base treatment polarizer and the optical film may be in the shape of a long strip. In the case of overlapping the polarizer with a base treatment so as to be disposed between a pair of optical films, as shown in FIG. 10 , in the first laminate 10 , the light base treatment polarizer 7 is a pair of optical films 5 , 9) is located between

The optical film may be bonded to the polarizer through an adhesive layer.

Lamination process WHEREIN: An adhesive layer can be formed in any one outermost surface of the 1st laminated body 10. As shown in FIG. The pressure-sensitive adhesive layer is, for example, by applying the pressure-sensitive adhesive to the surface on the opposite side to the non-basic treatment polarizer 7 of any one of the pair of optical films 5 and 9 to form a pressure-sensitive adhesive layer, and a separate film capable of being peeled from the pressure-sensitive adhesive layer thereon. It can form by joining. Moreover, in a lamination|stacking process WHEREIN: The protection film which can peel from an optical film can be bonded to any one outermost surface of the 1st laminated body 10. As shown in FIG.

(Forming process)

In a molding process, the 1st laminated body 10 can be adjusted to the dimension which the dimension of the 1st laminated body 10 is easy to process. Moreover, you may form a mold release part in the outer edge part of the 1st laminated body 10 by a punching process or a cutting process. Cutting and/or punching processing can be performed by using a cutting blade, using a punching blade, or irradiating a laser beam. The laser light may be a CO ₂ laser. The elongate 1st laminated body can be made into the single-wafer-shaped 1st laminated body in a shaping|molding process.

A shaping|molding process WHEREIN: A 1st laminated body can perform a cutting process or a punching process individually or in the state which overlapped two or more.

(cutting process)

The manufacturing method of the polarizing plate may further include a cutting step of bringing the end mill into contact with the outer periphery of the first laminate or the second laminate to be described later, and moving the end mill along the outer periphery of the laminate. As shown in FIG. 10 , in the entire outer periphery of the first laminate 10 before the cutting process, the positions of the ends of the polarizer 7 and the optical films 5 and 9 with the slight base treatment may coincide with each other.

11 and 12, the end mill 50 used in the cutting process has a protruding blade (edge) 50e in a side surface substantially parallel to the rotation axis 50a thereof. In a cutting process, the side surface of the end mill 50 is brought into contact with the outer periphery (end surface) of the 1st laminated body 10, and the rotating end mill 50 is moved along the outer periphery of the 1st laminated body 10. . For example, the rotating end mill 50 can be moved along a path indicated by an arrow in FIG. 12 . As a result, the outer periphery (end surface) of the first laminate 10 is cut or polished by the blade 50e, the outer periphery (end surface) of the first laminate 10 is smoothed, and the concave portion 13 ) is formed, and the inner corner of the concave portion 13 is chamfered. 11 , after forming the second laminate 100 by overlapping the plurality of first laminates 10 , the side surface of the end mill 50 is applied to the outer periphery of the second laminate 100 ( end face), and the rotating end mill 50 may be moved along the outer periphery of the second laminate 100 . That is, in a cutting process, the outer periphery of the some 1st laminated body 10 which comprises the 2nd laminated body 100 can be collectively cut or polished with the end mill 50 . In the cutting process, corner portions positioned at both ends of the concave portion 13 and corner portions positioned at four corners of the first laminate 10 may be chamfered.

The cutting amount of the end mill in the cutting process may be, for example, 10 μm or more and 500 μm or less, and preferably 50 μm or more and 150 μm or less.

The cutting process may be repeated three or more times. For example, in the 3rd cutting process, the 1st laminated body 10 is hardly cut, and the chips which arose in the 2nd cutting process can be removed from the end surface of the 1st laminated body 10 . A plurality of end mills can be used in each cutting process.

The feed rate of the end mill in the cutting process may be 100 mm/min or more and less than 3000 mm/min. The rotation speed of the end mill in the cutting process may be, for example, 500 rpm or more and 60000 rpm or less, and preferably 10000 rpm or more and 60000 rpm or less. The cutting angle in the cutting process may be, for example, 30° or more and 70° or less, and preferably 45° or more and 65° or less. When the twist angle of the end mill 50 is α, the cutting angle β is defined as 90°-α. As shown in FIG. 11 , the torsion angle α of the end mill 50 is the direction d1 in which the blade 50e extends from the side surface of the end mill 50 and the rotation axis 50a of the end mill 50 . is the angle formed. The cutting angle β may be in other words an angle formed by the direction d1 in which the blade 50e extends and the direction d2 perpendicular to the rotation axis 50a. The diameter φ (thickness) of the end mill 50 used in the cutting process may be, for example, 3.0 mm or more and 6.0 mm or less.

(Base treatment process)

A base treatment can be performed by making a basic solution contact the edge part of the resin film containing the boric acid and iodine contained in a 1st laminated body. By performing a base treatment to the edge part of the resin film containing boric acid and iodine, a boric-acid low concentration site|part and a low iodine concentration site|part can be formed. Base treatment can be performed to the 2nd laminated body which overlapped the 1st laminated body, for example by 5 or more and 3000 or less sheets. The number of sheets overlapping the first laminate is preferably 7 or more, for example, 2000 sheets or 1000 sheets.

It is preferable that the basic solution used for a base treatment contains water. The basic solution may be, for example, a solution in which a strongly basic compound is dissolved in a solvent, and is preferably an aqueous solution of the strongly basic compound. The strongly basic compound preferably includes sodium hydroxide and/or potassium hydroxide.

The temperature of the basic solution brought into contact with the end of the resin film containing boric acid and iodine may be at a temperature of 50 ° C. or less, and optical performance degradation (polarization degree decrease, color change, etc.) due to orientation confusion of the polarizer in the polarizing plate From a viewpoint of suppressing and reducing a boric acid concentration, Preferably it is the temperature of 45 degrees C or less, More preferably, it is the temperature of 40 degrees C or less, Usually, it is the temperature of room temperature or more.

The time for bringing the end of the resin film containing boric acid and iodine into contact with the basic solution may be within 6 minutes, and deterioration of optical performance due to orientation confusion of the polarizer in the polarizing plate (lower polarization, color change, etc.) It is suppressed and from the viewpoint of lowering the concentration of boric acid, it may be preferably within 5 minutes, and is usually longer than 1 minute.

The concentration of the basic compound in the basic solution may be, for example, 0.1 mol/liter or more and 4 mol/liter or less, preferably 1 mol/liter or more and 3 mol/liter or less, and more preferably 1.5 mol/liter or more and 2.5 mol/liter or more. is below.

As a method of bringing the end of the resin film containing boric acid and iodine into contact with the basic solution, for example, all or part of the first laminate or the second laminate is immersed in a bath containing a basic solution, and The method of spraying a basic solution on all or part of a 1st laminated body or a 2nd laminated body, etc. are mentioned.

After contacting with the basic solution, the resin film containing boric acid and iodine can be washed with water. It is preferable to perform water washing twice or more. Washing with water can be performed, for example, by a method of immersing the first laminate or the second laminate in a tank containing water, and/or a method of spraying water on the first laminate or the second laminate.

By the above method, the polarizing plate which concerns on this embodiment is obtained.

<Image display device>

The above-mentioned polarizing plate can be used for an image display apparatus. As an image display device, a liquid crystal display device, an organic electroluminescent display, etc. are mentioned, for example. A polarizing plate may be used for the polarizing plate arrange|positioned at the visual recognition side of an image display apparatus, may be used for the polarizing plate arrange|positioned at the backlight side of an image display apparatus, and may be used for both the polarizing plate of the visual recognition side and a backlight side. In the polarizing plate of this embodiment, since a color omission point is hard to be conspicuous, even if it is a case where it is used for the visual recognition side of an image display apparatus, designability is hard to be impaired. Therefore, the image display apparatus is suitable as an image display apparatus having a camera hole, for example, an image display apparatus used in mobile devices such as smartphones and mobile phones, personal computers, and the like.

Example

Hereinafter, the present invention will be described in more detail by way of Examples. "%" and "part" in an example are mass % and mass part, unless otherwise indicated.

[Condensation Heat Shock Test]

For each Example and Comparative Example, it tested according to the following procedure about the polarizing plate of 3 sheets.

(1) The surface of the optical film side having a thickness of 21 μm of the polarizing plate and the surface of a glass plate (made by Corning Corporation) wiped with ethanol were bonded through an adhesive layer, and autoclave treatment (50° C., 0.5 MPa, 20 minutes) was performed. .

(2) After autoclaving, it was confirmed by optical microscope observation that cracks did not occur in two corner end regions (circled portions in Fig. 15 ) in the concave-shaped portion of the polarizing plate.

(3) The polarizing plate was installed in a dew condensation heat shock oven, and the following operation was made into 1 cycle, and 10 cycles were repeated.

First, the polarizing plate was cooled by maintaining it at -40°C for 30 minutes. Then, it was exposed to outdoor air at 25° C. for 5 minutes. Then, it heated to 85 degreeC, and hold|maintained for 30 minutes under 85 degreeC drying conditions. Thereafter, it was cooled to 25°C, held for 5 minutes, and then cooled to -40°C. Moreover, when exposed to 25 degreeC outdoor air for 5 minutes, the surface of a polarizing plate was condensed, and after that, it heated at 85 degreeC with the dew condensation state. The dew condensation state was eliminated in the polarizing plate after being kept under 85°C dry conditions.

(4) Condensation The polarizing plate was taken out from the heat shock oven, and the number, average length, and maximum length of the cracks generated were measured using an optical microscope at two corners of the concave shape observed under an optical microscope in (2) above. Moreover, the distance from the edge part of a polarizing plate was measured about the area|region in which the iodine low concentration site|part was formed using the optical microscope.

[Measurement of boric acid concentration]

The distribution of the concentration of borate ions (BO ₃ ^3- ) was obtained by time-of-flight secondary ion mass spectrometry (TOF-SIMS). As shown in FIG. 13, the protective film bonded to the optical film 5 (52 micrometers) side of the polarizing plate 110 is peeled, and it bonds on the adhesive layer of the optical film 9 (21 micrometers in thickness) side. One separate film was peeled off, and one end region including the corner of the concave portion was cut out with a width of 100 μm and a length of 1 mm (1000 μm) toward the inside of the polarizing plate to obtain a measurement sample 200 . The measurement sample 200 includes an optical film 201 (thickness 52 μm), an adhesive layer 202 (thickness 1 μm), a polarizer 203 (thickness 8 μm), an adhesive layer 204 (thickness 1 μm), and an optical film. (205) (thickness 21 µm) and the pressure-sensitive adhesive layer 206 (thickness 20 µm) in this order. The ion beam is irradiated while scanning the measurement area 207 in the longitudinal direction (1000 µm) side of the measurement sample 200 to obtain a two-dimensional distribution of the signal intensity of borate ions on this side, and the obtained two-dimensional distribution A portion corresponding to the side surface of the polarizer was cut out from the polarizer, and the integrated value of the signal intensity was plotted in the longitudinal direction of the measurement sample 200 to obtain a profile of the boric acid concentration in the longitudinal direction. The conditions of the time-of-flight secondary ion mass spectrometry (TOF-SIMS) are shown below.

Moreover, the measurement of the boric acid concentration was performed in the state of a polarizing plate, and the obtained boric acid concentration can be regarded as the boric acid concentration of a polarizer.

Device name: Product name: PHI TRIFT V nano TOF (Urvac Pi Co., Ltd.)

Irradiated primary ion: Au ₃ ⁺

Primary ion acceleration voltage: 30 kV

Spatial resolution of the ion beam: 1 μm × 1 μm

Area of measurement area: 200 μm×200 μm

From the obtained boric acid concentration profile, the average value of the boric acid ion strength in the range of 30 µm or more and 60 µm or less from the end is obtained, and from the end to the position where the boric acid ion strength becomes the average value, the boric acid low concentration site is defined as the polarizing plate The length of the area|region (length of a boric-acid low concentration site|part) in which the boric-acid low concentration site|part from the edge part was formed was measured.

[Evaluation of low iodine concentration sites]

The base-treated portion of the polarizing plate is observed with transmitted light under an optical microscope, an optical microscope image is captured on a personal computer, and the length of the region in which the low iodine concentration portion is formed from the end of the polarizing plate as follows (low iodine concentration portion) length) was measured.

In the optical microscope image captured on the personal computer, the low iodine concentration region appears bright and the inner region appears dark with the naked eye. Image processing is performed on the optical microscope image, so that the brightness of the low iodine concentration part becomes 180-220 and the brightness of the inner region becomes 100-140, so that it is converted into a black-and-white image of 256 gradations (brightness 255 is white, 0 is black), A region (white) having a brightness of 180 or more was used as a low iodine concentration region, and the average value of the length from the end was obtained.

[Production of Polarizer]

(1st laminated body)

With reference to FIG. 14, manufacture of the 1st laminated body 10 is demonstrated. The first laminate 10 was formed by bonding a pair of optical films 5 and 9 to the polarizer 7 via the adhesive layers 6 and 8 . The first laminate 10 was rectangular. In the first laminate 10 , the polarizer 7 was disposed between a pair of optical films 5 and 9 . Both of the pair of optical films 5 and 9 are made of a cyclic olefin polymer-based resin. The polarizer 7 was stretched and dyed film-type polyvinyl alcohol.

An adhesive was apply|coated to the optical film 9 side of the 1st laminated body 10, the adhesive layer 41 was formed, and the separator film 42 was bonded together on it. This separate film was peelable from an adhesive layer. The protection film 43 was bonded together on the optical film 5 side of the 1st laminated body 10. As shown in FIG.

This protection film 43 was peelable from the optical film 5.

The thickness of the optical film 5 bonded to one surface of a polarizer was 52 micrometers. The thickness of the optical film 9 bonded to the other surface of the polarizer was 21 µm. The thickness of the polarizer 7 was 8 μm. The thickness of the whole 1st laminated body 10 was 103 micrometers. The adhesive layer 6 interposed between the optical film 5 and the polarizer 7 having a thickness of 52 µm was a polyvinyl alcohol-based resin (water glue). The adhesive layer 8 interposed between the optical film 9 and the polarizer 7 having a thickness of 21 μm was a UV curable epoxy resin.

(Release processing)

1st laminated body which formed the adhesive layer 41 on the side of the optical film 9 in the said procedure, the separate film 42 was bonded on it, and the protection film 43 was bonded together on the optical film 5 side in the said procedure. 47 sheets of (10) were prepared, and a recessed part was formed in the short side of each 1st laminated body by punching using a Thomson blade, respectively. The shape of this concave part was the same in all 47 sheets in the 1st laminated body. A second laminate was produced by polymerizing the 47 sheets of the first laminate in which the concave portion was formed. In all 47 sheets of this 2nd laminated body, the long side and short side of the 1st laminated body coincided, and it was set as that the concave shape part coincided.

After the punching process, the following three cutting steps were performed. In any cutting process, the rotating end mill is rotated around the outer periphery of the second laminate (including the concave portion) while the second laminate is clamped and the side surface of the end mill is in contact with the outer periphery (end surface) of the second laminate. was moved along the outer periphery). That is, the entire outer periphery of each of the 47 first laminates was collectively cut with an end mill. The end mill used for each cutting process was Nisshin Tool Co., Ltd. DXL-4. The cutting angle β was a value shown in Table 1 below. The diameter phi of the end mill was 4 mm.

The amount of cutting in the first cutting step was a value shown in Table 1 below. The rotational speed R of the end mill in the 1st cutting process was 30000 rpm. The feed rate (V) of the end mill in the 1st cutting process was 1000 mm/min.

The amount of cut in the second cutting step was the value shown in Table 1 below. The rotational speed R of the end mill in the 2nd cutting process was 30000 rpm. The feed rate (V) of the end mill in the 2nd cutting process was 1000 mm/min.

The amount of cut in the third cutting step was the value shown in Table 1 below. The rotational speed R of the end mill in the 3rd cutting process was 30000 rpm. The feed rate (V) of the end mill in the 3rd cutting process was 1000 mm/min.

47 polarizing plates were produced by the above method. The shape, dimension, and laminated structure of each polarizing plate were the same. The overall shape of each polarizing plate was a rectangle. In FIG. 15, the shape by planar view of the obtained polarizing plate 110 is shown. As shown in FIG. 15 , the polarizing plate 110 has a rectangular concave portion 113 formed on its short side. The length of the short side of the polarizing plate 110 was 70 mm.

The length of the long side of the polarizing plate 110 was 140 mm. The width 111 of the concave portion 113 was 30 mm. The depth 112 of the concave portion 113 was 5 mm. Further, the depth direction of the concave portion 113 was parallel to the absorption axis (stretching direction).

<Example 1>

The polarizing plate of Example 1 was obtained by laminating|stacking ten polarizing plates processed into the said shape, and performing an end base process in the following conditions and procedure.

(1) It was immersed for 5 minutes in NaOH aqueous solution at a density|concentration of 2 mol/liter, 40 degreeC.

(2) Next, the laminated polarizing plate was washed for 1 minute each in the order of the water washing tank 1 (20°C) and the water washing tank 2 (20°C).

After the said end base treatment, the measurement of the boric acid concentration and the condensation heat shock test were done about the polarizing plate of 3 sheets. A result is shown in Table 1. In addition, the TOF-SIMS analysis result (a) and the optical microscopy image (b) of the end region are shown in FIG. 16 .

As for this polarizing plate, the boric-acid low concentration site|part is formed in the area|region including an edge part with a width|variety of 20 micrometers from an edge part. Moreover, in this polarizing plate, the low iodine concentration site|part is also formed in the area|region including an edge part with a width|variety of 50 micrometers from an edge part.

<Comparative Example 1>

About the three polarizing plates processed into the said shape, the measurement of a boric-acid density|concentration and the condensation heat shock test were done, without performing the end base process of Example 1. A result is shown in Table 1. In addition, the TOF-SIMS analysis result (a) and the optical microscopy image of the end region (b) are shown in FIG. 17 .

In this polarizing plate, a boric acid low concentration site|part is formed in the area|region including an edge part with a width|variety of 12 micrometers from an edge part. In addition, in this polarizing plate, the low iodine concentration site|part was not formed in the area|region including an edge part.

<Comparative Example 2>

In Example 1, the polarizing plate of Comparative Example 2 was obtained in the same manner as in Example 1 except that the polarizing plate was immersed for 1 minute instead of being immersed in the NaOH aqueous solution for 5 minutes. In addition, the TOF-SIMS analysis result (a) and the optical microscopy image of the end region (b) are shown in FIG. 18 .

In this polarizing plate, a boric acid low concentration site|part is formed in the area|region including an edge part with a width|variety of 14 micrometers from an edge part. Moreover, in this polarizing plate, in the area|region including an edge part, the low iodine concentration site|part with a width|variety of 18 micrometers from an edge part is also formed.

In Example 1, the number of cracks was small, the average crack length and the maximum crack length were short, and the region in which the low iodine concentration site was formed was very small.

In Comparative Example 1, the number of cracks was large, the average crack length and the maximum crack length were long, and crack generation was not suppressed.

In Comparative Example 2, although the number of cracks was reduced, the average crack length and the maximum crack length were long, and cracks were not sufficiently suppressed.

ADVANTAGE OF THE INVENTION According to this invention, generation|occurrence|production of a crack is suppressed in the above-mentioned condensation heat shock test, and it turns out that the polarizer in which an iodine loss is not conspicuous is obtained.

DESCRIPTION OF SYMBOLS 1: Polarizing plate, 2: Polarizer, 3: First optical film, 4: Second optical film, 5, 9: Optical film, 7: Min base treatment polarizer, 10: First laminate, 11: Region I, 12: Regions II, 13, 113: concave portion, 14: through hole, 15: third optical film, 20: image display device, 21: polarizing plate, 22: camera hole, 23: liquid crystal panel, 24: cover glass, 25: Adhesive layer, 26: polarizing plate, 27: camera, 28: light-shielding tape, 30: low boric acid concentration region, 31: middle region, 32: inner region, 33: low iodine concentration region, 34: middle region, 41: adhesive layer, 42: Separate film, 43: protection film, 50: end mill, 50 a: rotation axis, 50 e: blade (edge), 100: second laminate, 110: polarizing plate, 111: width, 112: depth, 200: measurement sample , 201, 205: optical film, 202, 204: adhesive layer, 203: polarizer, 206: adhesive layer, 207: measurement area, α: twist angle, β: cutting angle

Claims (14)

As a polarizer which is a resin film containing boric acid and iodine,
In the region including the end portion in plan view, a boric acid low concentration region having a lower concentration of boric acid than the concentration of boric acid in the inner region 500 μm or more inside from the end portion is formed;
In the region including the end portion, a low iodine concentration region having a lower iodine concentration than that in the inner region is formed,
A polarizer having a length of 19 μm or more and 100 μm or less from the end of the low iodine concentration region. The polarizer according to claim 1, wherein the concentration of boric acid in the low boric acid concentration region decreases as it approaches the end portion in a direction from the inner side to the end portion in a planar view of the polarizer. The light polarizer according to claim 1 or 2, wherein the boric acid low concentration region is formed in a region of 15 µm or more inward from the end portion in the planar view. The polarizer according to any one of claims 1 to 3, wherein the boric acid low concentration region and the low iodine concentration region are formed along an outer edge of the polarizer. The polarizer according to any one of claims 1 to 4, wherein the polarizer has a deformable portion in plan view, and in an end region included in the deformable portion, the boric acid low concentration portion and the low iodine concentration portion are formed. polarizer. The polarizer according to claim 5, wherein the deformable portion is a concave portion formed in a peripheral portion or a through hole formed in the polarizer surface. The polarizing plate which has the polarizer in any one of Claims 1-6, and the optical film arrange|positioned at one or both sides of the said polarizer. The image display apparatus provided with the polarizing plate of Claim 7. The image display device according to claim 8, having a camera hole. A method for producing a polarizing plate comprising: a polarizer that is a resin film containing boric acid and iodine; and an optical film disposed on one or both sides of the polarizer;
A method for manufacturing a polarizing plate comprising a base treatment step of bringing a basic solution having a temperature of 50° C. or less into contact with the end of the resin film containing boric acid and iodine in 6 minutes or less. The method of claim 10 , wherein the basic solution includes water. The method for manufacturing a polarizing plate according to claim 10 or 11, wherein the basic solution is a solution in which a strong basic compound is dissolved in a solvent. The method of claim 12, wherein the strongly basic compound comprises sodium hydroxide and/or potassium hydroxide. 14. The method according to any one of claims 10 to 13, further comprising a molding step of molding the resin film containing boric acid and iodine into a predetermined shape by cutting and/or punching, wherein the molding step is A method for producing a polarizing plate in which the resin film after roughing is subjected to the base treatment step.

Images