阅读说明：本技术 偏振板 (Polarizing plate ) 是由 稻田清孝 于 2020-02-10 设计创作，主要内容包括：本发明提供一种不易产生伴随着温度变化的裂纹的偏振片。偏振板(100)具备：偏振片层(30)、设于所述偏振片层(30)的一个表面的第一光学树脂膜(10)、和设于所述偏振片层(30)的另一个表面的第二光学树脂膜(50)。从厚度方向观察所述偏振板(100),所述偏振板(100)的外周缘的形状具有凹部、凸部、以及曲线部中的至少一个。偏振片层(30)的端面的算术平均高度(Sa)为0.3～0.7μm,或者均方根高度(Sq)为0.4～0.8μm。(The invention provides a polarizing plate which is not easy to generate cracks along with temperature change. A polarizing plate (100) is provided with: the polarizer layer (30), a first optical resin film (10) provided on one surface of the polarizer layer (30), and a second optical resin film (50) provided on the other surface of the polarizer layer (30). The polarizing plate (100) is seen from the thickness direction, and the shape of the outer peripheral edge of the polarizing plate (100) has at least one of a concave part, a convex part, and a curved part. The arithmetic average height (Sa) of the end face of the polarizer layer (30) is 0.3 to 0.7 [ mu ] m, or the root mean square height (Sq) is 0.4 to 0.8 [ mu ] m.)

1. A polarizing plate comprising a polarizer layer, a first optical resin film provided on one surface of the polarizer layer, and a second optical resin film provided on the other surface of the polarizer layer,

the polarizing plate is formed such that the outer peripheral edge of the polarizing plate has at least one of a concave portion, a convex portion, and a curved portion when viewed in the thickness direction,

the arithmetic average height Sa of the end faces of the polarizer layer is 0.3 to 0.7 μm.

2. A polarizing plate comprising a polarizer layer, a first optical resin film provided on one surface of the polarizer layer, and a second optical resin film provided on the other surface of the polarizer layer,

the polarizing plate is formed such that the outer peripheral edge of the polarizing plate has at least one of a concave portion, a convex portion, and a curved portion when viewed in the thickness direction,

the root mean square height Sq of the end face of the polarizer layer is 0.4-0.8 μm.

3. The polarizing plate of claim 2,

the arithmetic average height Sa of the end faces of the polarizer layer is 0.3 to 0.7 μm.

4. The polarizing plate according to any one of claims 1 to 3,

the maximum height Sz of the end face of the polarizer layer is 5.0 [ mu ] m or less.

Technical Field

The present invention relates to a polarizing plate.

Background

The polarizing plate generally includes a polarizer layer containing a coloring matter, and a pair of optical resin films provided on both sides of the polarizer layer, and is used by being bonded to a display panel such as a liquid crystal cell or an organic EL element. The outer periphery of the polarizing plate is generally shaped to conform to the outer peripheral edge of the display portion of the display panel.

When the outer peripheral edge of the display portion of the display panel has at least one of a concave portion, a convex portion, and a curved portion instead of a rectangular shape in a plan view, the outer peripheral edge of the polarizing plate used in the display portion also has at least one of a concave portion, a convex portion, and a curved portion instead of a rectangular shape (see, for example, patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-92119

Disclosure of Invention

Problems to be solved by the invention

As a result of research, the present inventors have found that a polarizing plate having at least one of a concave portion, a convex portion, and a curved portion instead of a rectangular shape at the outer peripheral edge is more likely to be discolored from a polarizer layer in a hot and humid environment and to be easily peeled from a polarizer at an end face than a polarizing plate having a rectangular shape at the outer peripheral edge. Such a phenomenon is more likely to occur in the concave portion, the convex portion, and the curved portion, or in the vicinity thereof, than in the straight portion.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a polarizing plate having at least one of a concave portion, a convex portion, and a curved portion at an outer peripheral edge thereof, in which discoloration under a wet and hot environment is less likely to occur, and in which peeling of an optical resin film from a polarizer layer is less likely to occur at an end face.

Means for solving the problems

The polarizing plate of the present invention includes a polarizer layer, a first optical resin film provided on one surface of the polarizer layer, and a second optical resin film provided on the other surface of the polarizer layer. The polarizing plate has a shape of an outer peripheral edge having at least one of a concave portion, a convex portion, and a curved portion when viewed in a thickness direction, and an arithmetic average height Sa of an end face of the polarizer layer is 0.3 to 0.7 [ mu ] m.

Another polarizing plate according to the present invention includes a polarizer layer, a first optical resin film provided on one surface of the polarizer layer, and a second optical resin film provided on the other surface of the polarizer layer. In addition, the root mean square height Sq of the end face of the polarizer layer is 0.4-0.8 μm. The arithmetic average height Sa of the end face may be 0.3 to 0.7 μm.

The polarizing plate of the present invention may have a maximum height Sz of the end face of the polarizer layer of 5.0 μm or less.

Effects of the invention

According to the present invention, it is possible to provide a polarizing plate having at least one of a concave portion, a convex portion, and a curved portion at an outer peripheral edge, in which discoloration under a wet and hot environment is less likely to occur, and in which peeling of an optical resin film from a polarizer layer is less likely to occur at an end face.

Drawings

Fig. 1 is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention.

Fig. 2 (a) to (c) are plan views of the polarizing plate according to one embodiment of the present invention.

Fig. 3 is a cross-sectional view perpendicular to the axis near the tip of the end mill.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals are used for the same components. The present invention is not limited to the following embodiments.

(polarizing plate)

Fig. 1 shows an end surface view of a polarizing plate 100 according to an embodiment of the present invention. The polarizing plate 100 of the present embodiment includes a first optical resin film 10, an adhesive layer 20, a polarizer layer 30, an adhesive layer 40, and a second optical resin film 50 in this order.

Examples of the polarizer layer 30 include a resin layer dyed with a dichroic dye such as iodine or a dichroic dye, and may be stretched. The resin constituting the resin layer may be a hydrophobic resin, but is usually a hydrophilic resin. Examples of the hydrophilic resin are a polyvinyl alcohol resin, a polyvinyl acetate resin, and an ethylene/vinyl acetate copolymer resin (EVA) resin. Examples of the hydrophobic resin include polyamide resins and polyester resins. Polarizer layer 30 may be treated with boric acid after dyeing. A typical example of the polarizer layer 30 is a resin layer in which iodine is adsorbed and oriented on a polyvinyl alcohol film. When the resin layer as the polarizer layer is made of a hydrophilic resin such as a polyvinyl alcohol resin, the entrance and exit of moisture to and from the outside is large compared with the hydrophobic resin, and this is considered to cause discoloration in a hot and humid environment and peeling of the optical resin film from the polarizer layer at the end face.

The thickness of the polarizer layer 30 may be, for example, 2 to 30 μm, 2 to 15 μm, or 2 to 10 μm.

The first optical resin film 10 and the second optical resin film 50 are generally colorless and transparent resin films. Examples of such resin films are protective films, retardation films, brightness enhancement (reflection-type polarizing plate) films, antiglare films, surface reflection prevention films, reflective films, semi-transmissive reflective films, viewing angle compensation films, optical compensation films, touch sensor films, antistatic films, and antifouling films.

Examples of the resin constituting each optical resin film may be a cellulose-based resin (triacetyl cellulose or the like), a polyolefin-based resin (polypropylene-based resin or the like), a cycloolefin-based resin (norbornene-based resin or the like), an acrylic-based resin (polymethyl methacrylate-based resin or the like), or a polyester-based resin (polyethylene terephthalate-based resin or the like). The first optical resin film 10 and the second optical resin film 50 may be multilayer films.

The thickness of the first optical resin film 10 and the second optical resin film 50 may be, for example, 5 to 200 μm.

The material and thickness of the first optical resin film 10 and the second optical resin film 50 may be the same or different from each other.

The material of the adhesive layers 20 and 40 is not particularly limited as long as it is a transparent material capable of adhering the polarizer layer 30 to the first optical resin film 10 or the second optical resin film 50. An example of the adhesive is an epoxy resin. The epoxy resin may be, for example, a hydrogenated epoxy resin, an alicyclic epoxy resin, or an aliphatic epoxy resin. A polymerization initiator (photo cation polymerization initiator, thermal cation polymerization initiator, photo radical polymerization initiator, thermal radical polymerization initiator, or the like), or other additives (sensitizer, or the like) may be added to the epoxy resin.

Another example of the adhesive is an acrylic resin such as acrylamide, acrylate, urethane acrylate, and epoxy acrylate.

Another example of the adhesive is an aqueous adhesive such as a polyvinyl alcohol resin.

Another example of the adhesive is a pressure-sensitive adhesive. Examples of the pressure-sensitive adhesive include pressure-sensitive adhesives containing acrylic resins, silicone resins, polyesters, polyurethanes, polyethers, or the like.

The polarizer layer 30 and the first optical resin film 10 may be laminated only via the adhesive layer 20, or an easy-adhesion layer (not shown) may be provided between the polarizer layer 30 and the adhesive layer 20, or between the adhesive layer 20 and the first optical resin film 10. The polarizer layer 30 and the second optical resin film 50 may be laminated only via the adhesive layer 40, or an easy-adhesion layer (not shown) may be provided between the polarizer layer 30 and the adhesive layer 40, or between the adhesive layer 40 and the second optical resin film 50. The easy-adhesion layer is a layer capable of improving adhesion between the adhesive layers 20 and 40 and the polarizer layer 30, the first optical resin film 10, or the second optical resin film 50.

The thickness of the adhesive layer 20 may be, for example, 0.01 to 5 μm, 0.05 to 3 μm, or 0.1 to 1 μm. When a pressure-sensitive adhesive is used, the thickness of the adhesive layer 20 may be, for example, 2 to 500. mu.m, 2 to 200. mu.m, or 2 to 50 μm.

The entire thickness of the polarizing plate 100 may be, for example, 10 to 500 μm, 10 to 300 μm, or 10 to 200 μm.

A pressure-sensitive adhesive layer (adhesive layer) and a separator film may be further provided under the first optical resin film 10 or on the second optical resin film 50. In addition, a protective film may be further provided below the first optical resin film 10 or above the second optical resin film 50.

The separator film is a film that can be peeled from the pressure-sensitive adhesive layer and prevents adhesion of foreign matter to the pressure-sensitive adhesive layer. For example, when the polarizing plate 100 is bonded to an image display element, the separator film is peeled off to expose the pressure-sensitive adhesive layer. The resin constituting the separator film may be, for example, a polyethylene-based resin, a polypropylene-based resin, or a polyester-based resin (polyethylene terephthalate or the like).

The pellicle is a film for preventing the first optical resin film 10 or the second optical resin film 50 from being scratched, and may be, for example, a single self-adhesive resin film or a multilayer film formed of a resin film and a pressure-sensitive adhesive laminated on the resin film. The pellicle can be peeled off from the first optical resin film 10 and the second optical resin film 50 on which the pellicle is provided. In the case where the protective film is a multilayer film in which a pressure-sensitive adhesive is laminated on a resin film, the protective film is peeled from the first optical resin film 10 or the second optical resin film 50 together with the pressure-sensitive adhesive. The resin of the cover film may be the same as the separator film.

The thickness of the separator film and the protective film may be, for example, 2 to 500 μm, 2 to 200 μm, or 2 to 100 μm.

The polarizing plate 100 of the present embodiment has at least one selected from a concave portion, a convex portion, and a curved portion, instead of being formed only by straight lines (for example, rectangular) when viewed in the thickness direction of the polarizing plate 100.

For example, like the polarizing plate 100 shown in fig. 2 (a), the outer peripheral edge P may have 4 linear portions PL orthogonal to each other and chamfered curved portions PR provided between the 2 linear portions PL. In other words, the outer peripheral edge P of the polarizing plate 100 is provided with chamfered curved portions PR at 4 corners of the rectangle.

In addition, like the polarizing plate 100 shown in fig. 2 (b), the concave portion PD may be further provided to one linear portion PL of the outer peripheral edge P of the polarizing plate 100 in fig. 2 (a). The shape of the concave portion PD is not limited, and may be, for example, an approximately rectangular shape having 3 straight line portions PDL orthogonal to each other as shown in fig. 2 (b), and may be a shape having chamfered curved portions PDR between the straight line portions PDL, and chamfered curved portions PDR between the straight line portions PDL and the straight line portions PL. The curved line portion PDR provided between the 2 linear portions PDL has a shape recessed in the plane of the polarizing plate 100. The chamfered curved portion PDR provided between the linear portion PDL and the linear portion PL is convex out of the plane of the polarizing plate 100.

As in the polarizing plate 100 shown in fig. 2 (c), the convex portion PP may be provided to one linear portion PL of the outer peripheral edge P of the polarizing plate 100 in fig. 2 (a). The shape of the convex part PP is not limited, and may be, for example, an approximately rectangular shape having 3 straight line parts PPL orthogonal to each other as shown in fig. 2 (c), and may have chamfered curved parts PPR between the straight line parts PPL and the straight line parts PL. The chamfered curved portion PPR provided between the 2 linear portions PPL is recessed into the surface of the polarizing plate 100. The chamfered curved portion PPR provided between the linear portion PPL and the linear portion PL is convex out of the plane of the polarizing plate 100.

The depth of the concave portion PD with respect to the linear portion PL and the height of the convex portion PP with respect to the linear portion PL are not particularly limited, but may be typically 1.0mm or more. The width of the concave portion PD and the width of the convex portion PP are also not particularly limited, but may be typically 3.0mm or more.

The shapes of the concave part PD and the convex part PP are not limited to a rectangle in which 4 corners are rounded by chamfered curved parts as in (b) and (c) of fig. 2, and may be a simple rectangle, a semicircle, a polygon, or the like.

The curve of each chamfer curve part can be a circular arc, an elliptical arc or a spline curve. The curvature radius of each chamfered curved portion may be set to 1.0 to 40 mm.

In the outer peripheral edge P of fig. 2 (a), 1 to 3 of the 4 chamfered curved portions PR may be simple corner portions other than the chamfered curved portions. In the outer peripheral edge P of fig. 2 (b) and (c), 1 to 4 of the 4 chamfered curved portions PR may be simple corner portions other than the chamfered curved portions. The outer peripheral edge P may be formed not only in a rectangular shape as shown in fig. 2 (a) to (c), but also in a polygonal shape such as a triangle or a hexagon.

The absorption axis of the polarizer layer 30 may be oriented in any direction of the polarizing plate 100 depending on the image display device or the like used.

(arithmetic mean height Sa)

Referring back to fig. 1, in the polarizing plate 100 according to the embodiment of the present invention, the arithmetic average height Sa of the end faces of the polarizer layer 30 of the polarizing plate 100 is 0.3 to 0.7 μm. Sa may be 0.4 μm or more and 0.6 μm or less.

The arithmetic mean height Sa of the end face of the polarizer layer 30 is defined as shown below in an arbitrary two-dimensional measurement region 30A on the end face. An XYZ coordinate system in which a plane parallel to the end face of the polarizer layer 30 is an XY plane, a height direction perpendicular to the end face is a Z direction, the position of the average height in the two-dimensional measurement region 30A of the end face is Z (0), and the arithmetic average height Sa is expressed by the following equation when the height at each x coordinate and each y coordinate of the two-dimensional measurement region 30A is Z (x, y). Here, a is the area of the two-dimensional measurement region 30A.

The height Z (x, y) of each x and y in the two-dimensional measurement region 30A can be obtained by a scanning interference microscope, an atomic force microscope, or the like. The size of the two-dimensional measurement region 30A may be, for example, a rectangular region having a side of 5 to 1000 μm.

(root mean square height Sq)

In addition, the root mean square height Sq of the end surface of the polarizer layer 30 may be 0.4 to 0.8 μm. Sq may be 0.5 μm or more, or 0.7 μm or less.

The root mean square height Sq in the arbitrary two-dimensional measurement region 30A can be defined by the following equation.

(maximum height Sz)

The maximum height Sz of the end surface of the polarizer layer 30 may be 5.0 μm or less. The Sz may be 4.0 μm or less.

The maximum height Sz is the sum of the absolute values of the maximum peak height and the maximum valley depth in the two-dimensional measurement area 30A.

The determination of the three-dimensional surface roughness in the two-dimensional determination region 30A may be in accordance with ISO 25178.

Here, the two-dimensional measurement region 30A is preferably a planar portion at an end face, which is any one of linear portions of the outer peripheral edge P, and may be a planar portion in the concave portion PD and the convex portion PP, or a planar portion other than the concave portion PD and the convex portion PP, for example, a planar portion on 4 linear portions PL orthogonal to each other.

As described later, unlike a polarizing plate in which the outer peripheral edge P is formed only by a straight portion, the end face of the polarizing plate having a concave portion, a convex portion, or a curved portion cannot be cut by a plane grinding apparatus to adjust the size. Therefore, the end face of such a polarizing plate is generally cut by an end mill over the entire outer periphery. Therefore, the end face has substantially the same surface roughness at any position of the end face.

A straight portion of the outer peripheral edge P, that is, a plane portion at the end face is preferably used as the two-dimensional measurement area 30A because a plane having an average height of 0 is a plane and it is easy to determine a plane having Z equal to 0.

It is also preferable that the two-dimensional measurement region 30A is located at an end in the absorption axis (stretching direction) direction of the polarizer layer 30. When the two-dimensional measurement region 30A is located at an end in the absorption axis direction, the region 30A intersects with the absorption axis of the polarizer layer 30.

When the arithmetic average height Sa at the end face of the polarizer layer 30 is large, the surface area of the end face becomes large, and thus the discoloration tends to become large in a hot and humid environment. On the other hand, if the arithmetic average height Sa at the end face of the polarizer layer 30 is small, the amount of peeling of the first optical resin film 10 and/or the second optical resin film 50 from the polarizer layer 30 tends to be large. The case where the Sa is small corresponds to a state where the optical resin film is not polished while keeping the shape after punching with a thomson blade, and is estimated to be caused by peeling of the optical resin film due to impact of punching.

When the root mean square height Sq at the end face of the polarizer layer 30 is large, the surface area of the end face becomes large, and thus discoloration tends to become large in a hot and humid environment. On the other hand, if the root-mean-square height Sq at the end face of the polarizer layer 30 is small, the amount of peeling of the first optical resin film 10 and/or the second optical resin film 50 from the polarizer layer 30 tends to be easily increased.

When the maximum height Sz at the end face of the polarizer layer 30 is large, the surface area of the end face becomes large, and thus discoloration tends to become large in a hot and humid environment.

Such a polarizing plate can be used in an image display device such as a liquid crystal display device or an organic EL display device after being bonded to a display panel such as a liquid crystal cell or an organic EL element. The liquid crystal display device may include, for example, a liquid crystal cell and the above-described polarizing plate attached to one surface or both surfaces of the liquid crystal cell. The organic EL display device may include, for example, an organic EL element and the above-described polarizing plate attached to a surface of the organic EL element. In the liquid crystal cell, 2 polarizing plates are generally arranged.

(method for producing polarizing plate)

Next, a method for manufacturing the polarizing plate 100 will be described.

First, a material of the polarizing plate 100 having the above-described layer structure is manufactured by a known method. Next, the raw material film is punched out with a tool such as a thomson knife to obtain a polarizing plate having a concave portion, a convex portion, or a curved portion at the outer peripheral edge P. Here, since it is difficult to secure sufficient dimensional accuracy in the outer peripheral edge P by only the thomson blade, the end surface grinding step is performed.

When the outer peripheral edge P has a concave portion, a convex portion, or a curved portion, the entire end face of the polarizing plate cannot be ground using a plane grinding apparatus used for grinding the end face of the rectangular polarizing plate, and therefore, the entire end face of the polarizing plate is cut using an end mill, in which a rotating disk having a plurality of turning tools (japanese patent No. バイト) arranged in a circumferential direction on one main surface is brought into contact with the end face of the polarizing plate so that the main surface is parallel to the end face of the polarizing plate. More specifically, the axial direction of the end mill is made parallel to the thickness direction of the polarizing plate, and the end mill and the polarizing plate are moved relatively along the end face of the polarizing plate, whereby the end face of the polarizing plate is cut to fit a desired size.

Here, an end mill having a helical cutting edge is preferably used, and an end mill having a cutting edge with a cross-sectional shape with a small value of dZ and dZ/dX in fig. 3 is particularly preferably used.

Here, fig. 3 is a cross-sectional view of the tip of the cutting edge 80 in a cross-section perpendicular to the axis of the end mill, where the rotation direction of the end mill is C. The cutting edge 80 has a cutting edge 80t and a surface 80d located on the rear side of the cutting edge 80 t. The surface 80d can be brought into contact with the workpiece T immediately after cutting by the cutting edge 80T. In the present embodiment, the profile of the height of the surface 80d with respect to the straight line AB is measured by a scanning interference microscope while moving along the straight line AB that is orthogonal to the straight line Q and passes through the cutting edge 80t with the straight line Q connecting the cutting edge 80t and the rotation axis AX of the end mill as a starting point. Then, from the profile, dZ [ μm ] which is the maximum value of the height of the surface 80d and a distance dX [ μm ] from the cutting edge 80t in the AB direction which causes dZ are obtained.

In this case, an end mill having a tip with dZ. ltoreq.1.0 μm and dZ/dX. ltoreq.4 is suitably used. This makes it easy to set the surface roughness of the end face 20e of the polarizer layer 30 to the above range. Even in the case of an end mill having a helical cutting edge, the surface roughness tends to be too large in the case of an end mill having a dZ of > 1.0 μm or a dZ/dX of > 4.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

For example, it can be implemented without one or both of the adhesive layers 20 and 40.

Examples

The present invention will be described in more detail below with reference to examples and comparative examples. The present invention is not limited to the following examples.

[ example 1]

A polyvinyl alcohol resin film having a thickness of 20 μm was stretched and stained with iodine, thereby producing a polarizing plate (thickness: 8 μm) in which iodine was adsorbed to the polyvinyl alcohol resin and oriented. A cycloolefin resin (COP) film (13 μm thick, manufactured by ZEON corporation) was bonded to one surface of the polarizing plate via an aqueous adhesive. Then, an acrylic pressure-sensitive adhesive layer a (thickness 20 μm) formed on the release film was laminated on the COP film. An acrylic pressure-sensitive adhesive layer B (thickness: 5 μm) formed on a release film was laminated on the other side of the polarizing plate. A brightness enhancement film (APF-V3, manufactured by 3M Co., Ltd., thickness 30 μ M, reflection type polarizing plate) having a pellicle film on the upper surface thereof was bonded to the acrylic pressure-sensitive adhesive layer B exposed by peeling off the release film.

In this manner, a polarizing plate material formed of a release film, an acrylic pressure-sensitive adhesive layer a, a COP film, an aqueous adhesive, a polarizer, an acrylic pressure-sensitive adhesive layer B, a brightness enhancement film, and a protective film was produced.

The polarizing plate 100 is cut out from a material by a thomson knife to have a concave portion PD having the shape of fig. 2 (b). The length of the long side of the rectangle is 140mm, the length of the short side of the rectangle is 70mm, the depth of the recess is 5mm, the width of the recess is 30mm, the curvature radius of the chamfer curve part PR is about 10-12 mm, and the curvature radius of the chamfer curve part PDR is about 3 mm. Note that the polarizing plate 100 has 1 recess PD. The recess PD is approximately rectangular. The concave portion PD has 3 straight line portions PDL orthogonal between adjacent ones. The straight line portions PDL each have a chamfered curved portion PDR.

The straight line portions PDL and PL each have a chamfered curved portion PDR therebetween. The absorption axis 31 of the polarizing plate 100 is orthogonal to the depth direction of the concave portion PD, and is in the left-right direction in fig. 2 (b).

The polarizing plate of example 1 was obtained by adjusting the size by grinding the entire end face using an end mill having a spiral blade with a dZ of 0.6 μm on average and a dZ/dX of 2.2 on average.

Comparative example 1

A polarizing plate of comparative example 1 was obtained in the same manner as in example 1, except that the end face was polished using an end mill having a spiral blade with a dZ of 1.4 μm on average and a dZ/dX of 14 on average.

Comparative example 2

A polarizing plate of comparative example 2 was obtained in the same manner as in comparative example 1, except that the end face was not polished with an end mill, but cut with a thomson knife.

(measurement of three-dimensional surface roughness Sa, Sq, and Sz)

The height function Z (x, y) of the end face of the polarizer layer was obtained by the following microscope.

Scanning type white light interference microscope VS1000 series Hitachi High-Tech Science Corporation

The measurement conditions were as follows: an objective lens: 50 is

Two-dimensional measurement area: the longitudinal (thickness direction) of a linear part (a surface orthogonal to an absorption axis) of an end face of a polarizer layer (PVA layer) of a polarizing plate is 5 to 8 [ mu ] m x the transverse (direction perpendicular to the thickness direction) is 150 to 300 [ mu ] m

Based on the obtained function Z, Sa, Sq, and Sz are obtained based on the above equation. The end surfaces of Sa, Sq, and Sz are measured on the left and right straight portions PL in fig. 2 (b) and are orthogonal to the absorption axis 31. Note that Sa, Sq, and Sz of each polarizing plate 100 show the same values over the entire circumference of the object to be measured.

(evaluation of deiodination)

The polarizing plate obtained in example or comparative example was left to stand in an environment of 65 ℃ and a relative humidity of 90% for 500 hours.

Thereafter, 2 polarizing plates (one polarizing plate was a polarizing plate of example or comparative example, and the other was a commercially available ordinary polarizing plate) were arranged as crossed nicols, the end portions of the entire circumference were observed using an optical microscope, and the width of the region where no light reduction corresponding to the crossed nicols occurred (light leakage) with respect to the end portions was measured. This light leakage is caused by iodine desorption which plays a role of polarization performance. Light leakage occurs in the vicinity of the recess PD in fig. 2, and the maximum width thereof is determined as deiodination.

(evaluation of peeling amount of Brightness enhancement film)

Evaluation was performed using a reflection microscope.

The conditions and results are shown in table 1.

[ Table 1]

In embodiments, the amount of iodine removal can be reduced while also reducing the amount of peeling of the brightness enhancing film.

Industrial applicability

The polarizing plate of the present invention can be applied to, for example, a liquid crystal cell, an organic EL element, or the like, and is used as an optical member constituting an image display device such as a liquid crystal television, an organic EL television, or a smartphone.

Description of the reference numerals

10 first optical resin film, 30 polarizer layer, 50 second optical resin film, P outer peripheral edge, PP convex part, PD concave part, PR, PDR, PPR chamfer curve part, 100 polarizer plate.