JP6968854B2 - Polarizing plate manufacturing method and polarizing plate - Google Patents

Description

The present invention relates to a method for manufacturing a polarizing plate and a polarizing plate.

The polarizing plate is used as one of the optical components constituting an image display device such as a liquid crystal display device. Image display devices are also used in mobile terminals such as smartphones and tablets, and it is known that a polarizing plate is also incorporated in such mobile terminals.

In mobile terminals such as smartphones and tablets, the shape may be such that a recess is formed in the peripheral portion of the display (display portion). In a display having a recess as described above, a polarizing plate having a recess is used according to the shape of the display (for example, Patent Documents 1, 2, etc.). As a method for obtaining a polarizing plate having a concave portion, a method of punching using a cutting blade so as to form a concave portion in the raw material polarizing plate, a method of cutting the end face of the raw material polarizing plate to form a concave portion, and the like are known. (For example, Patent Document 2 and the like).

Japanese Unexamined Patent Publication No. 2018-25630 Japanese Unexamined Patent Publication No. 2018-12182

The cutting process on the end face of the raw material polarizing plate is usually performed twice or more. In this case, first, rough cutting is performed by cutting with a relatively large cutting width, and then finish cutting is performed by cutting with a relatively small cutting width.

When a polarizing plate having a concave portion was manufactured by performing the above-mentioned cutting process, it was found by a dew condensation heat shock test of the polarizing plate that long cracks may be generated around the concave portion. Some mobile terminals such as smartphones and tablets are being narrowed in frame from the viewpoint of expanding the display area and design. In a mobile terminal having such a narrow frame, it is difficult to conceal a long crack by the frame, which may cause a problem such as display failure.

An object of the present invention is to provide a method for manufacturing a polarizing plate and a polarizing plate capable of suppressing the generation of long cracks around the concave portion by a dew condensation heat shock test.

The present invention provides the following method for manufacturing a polarizing plate and a polarizing plate.
[1] A method for manufacturing a polarizing plate having a concave portion on the peripheral edge in a plan view.
A process of preparing a raw material polarizing plate having a protective layer on one side or both sides of a polarizing element layer, and
A step [a] of performing a cutting process so as to form the concave portion while moving the end mill relative to the peripheral portion of the raw material polarizing plate is included.
The cutting process in the step [a] is a method for manufacturing a polarizing plate, which is a cutting process performed so that the cutting width is 150 μm or less.
[2] The method for manufacturing a polarizing plate according to [1], wherein the raw material polarizing plate has a concave notch in a region where the concave portion is formed.
[3] The method for producing a polarizing plate according to [1] or [2], wherein the step [a] is performed twice or more.
[4] Further, [1] includes a step [b] of performing a cutting process so as to form a peripheral portion of the polarizing plate other than the concave portion while moving the end mill relative to the peripheral portion of the raw material polarizing plate. ] To [3]. The method for manufacturing a polarizing plate according to any one of.
[5] The method for manufacturing a polarizing plate according to [4], wherein the step [a] and the step [b] are continuously performed.
[6] The method for producing a polarizing plate according to any one of [1] to [5], wherein the polarizing element layer is a polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and oriented.
[7] A polarizing plate having a concave portion on the peripheral edge in a plan view.
The polarizing plate has a protective layer on one side or both sides of the polarizing element layer, and has a protective layer.
A polarizing plate having no craze at any of the positions 30 μm and 50 μm in the plane direction from the edge existing in an arbitrary range of 5 mm in length along the contour of the recess.
[8] Further, the polarizing plate according to [7], wherein the craze is present or is not present at a position 10 μm in the plane direction from the edge existing in the arbitrary range.
[9] The contour of the recess has a curved portion and a linear portion.
The polarizing plate according to [7] or [8], wherein the edge existing in the arbitrary range is an edge existing in a range of a length of 5 mm from the side adjacent to the curved portion in the linear portion. ..
[10] The contour of the recess includes two sides that are provided so as to face each other and have a linear portion, and one side that connects the two sides and has a linear portion.
The edge existing in the arbitrary range is an edge existing in a range of a length of 5 mm from the side where the one side and one of the two sides are in contact with each other in the linear portion of the one side. 7] The polarizing plate according to any one of [9].
[11] The polarizing plate according to any one of [7] to [10], wherein the polarizing element layer is a polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and oriented.

According to the present invention, it is possible to provide a polarizing plate capable of suppressing the generation of long cracks around the recesses by the condensation heat shock test.

It is a schematic plan view which shows an example of the polarizing plate of this invention schematically. It is a schematic front view which shows typically an example of the end mill used in the manufacturing method of the polarizing plate of this invention. (A) to (d) are schematic top views schematically showing an example of the method for manufacturing a polarizing plate of the present invention. (A) to (c) are schematic top views schematically showing an example of the method for manufacturing a polarizing plate of the present invention. (A) and (b) are explanatory views explaining the relationship between the rotation direction and the movement direction of an end mill. It is a schematic cross-sectional view schematically showing an example of the polarizing plate of this invention. (A) and (b) are views showing an image of a cross section of a polarizing plate observed with a scanning laser microscope. (A) and (b) are schematic plan views schematically showing another example of the polarizing plate of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Manufacturing method of polarizing plate)
FIG. 1 is a schematic plan view schematically showing an example of the polarizing plate of the present embodiment. The method for manufacturing a polarizing plate of the present embodiment is, for example, as shown in FIG. 1, a method for manufacturing a polarizing plate 10 having a recess 11 at a peripheral portion in a plan view. The method for manufacturing the polarizing plate 10 includes a step of preparing a raw material polarizing plate 30 having a protective layer on one side or both sides of the polarizing element layer, and a recess 11 while moving the end mill 50 relative to the peripheral portion of the raw material polarizing plate 30. The step [a] of performing a cutting process so as to form the above-mentioned. The cutting process in the step [a] is a cutting process performed so that the cutting width is 150 μm or less. The cutting process performed by the method for manufacturing the polarizing plate 10 includes a polishing process.

FIG. 2 is a schematic front view schematically showing an example of an end mill used in a method for manufacturing a polarizing plate. The end mill 50 is a cutting tool for cutting the end surface (surface along the thickness direction) of the raw material polarizing plate 30. As shown in FIG. 2, the end mill 50 is provided with a cutting portion 52 having a cutting blade 52a on the outer peripheral surface on one tip side of a tool body having a rotating shaft 51. In the end mill 50 shown in FIG. 2, the case where the cutting blade 52a is a right blade is shown, but the present invention is not limited to this. For example, the cutting blade 52a may be a left blade, and the twist direction of the blade may be a right twist or a left twist.

The cutting angle β of the end mill 50 may be, for example, 30 ° or more, 40 ° or more, 45 ° or more, and usually 70 ° or less, and 65 ° or less. .. The cutting angle β [°] of the end mill 50 is as follows, assuming that the helix angle of the end mill 50 is α [°].
β = 90 ° −α
It is represented by. As shown in FIG. 2, the twist angle α is an angle formed by the direction d1 in which the cutting blade 52a extends on the outer peripheral surface of the end mill 50 and the rotating shaft 51. In other words, as shown in FIG. 2, the cutting angle β is an angle formed by the direction d1 in which the cutting blade 52a extends and the direction d2 perpendicular to the rotation axis 51.

The diameter φ (maximum diameter drawn by the rotation of the cutting blade) of the end mill 50 may be, for example, 3 mm or more, 5 mm or more, 30 mm or less, or 10 mm or less. , 6 mm or less.

In the method of manufacturing the polarizing plate 10 by cutting the raw material polarizing plate 30 using the above end mill 50, for example, the raw material polarizing plate 30 placed on the mounting table of the cutting apparatus is fixed by a fixture such as a clamp. Then, by moving the end mill 50 or the mounting table, the cutting process is performed while the end mill 50 is relatively moved with respect to the peripheral edge portion of the raw material polarizing plate 30. The relative movement of the end mill 50 with respect to the peripheral portion of the raw material polarizing plate 30 can be performed, for example, as shown in FIGS. 3 (a) to 3 (d) and FIGS. 4 (a) to 4 (c). 3 (a) to 3 (d) and FIGS. 4 (a) to 4 (c) are schematic top views schematically showing an example of a method for manufacturing a polarizing plate.

In the method for manufacturing the polarizing plate 10, first, as shown in FIG. 3A, a step of preparing a raw material polarizing plate 30 cut into a predetermined shape and size is performed. FIG. 3A shows a rectangular raw material polarizing plate 30 having a concave notch 31 formed on one side. The raw material polarizing plate 30 can be obtained, for example, by forming a notch portion 31 by further performing a punching process, a cutting process, or the like on one side of a cut piece cut out in a rectangular shape by a punching process, a cutting process, or the like. can. The raw material polarizing plate 30 may be cut into a shape having a notch portion 31 by one punching process or one cutting process.

Next, a step of performing cutting while moving the end mill 50 relative to the peripheral edge of the raw material polarizing plate 30 (hereinafter, may be referred to as step [A]) is performed. The cutting process in the step [A] can be performed by bringing the cutting portion 52 of the end mill 50 that rotates about the rotating shaft 51 into contact with the end face of the raw material polarizing plate 30. The end face of the raw material polarizing plate 30 is a surface along the thickness direction (direction orthogonal to the plane direction) of the raw material polarizing plate 30. By performing the step [A], the recess 11 of the polarizing plate 10 is formed in the region of the notch 31 of the raw material polarizing plate 30 (step [a]), and the polarizing plate 10 is formed in the region other than the notch 31. A peripheral edge portion other than the recess 11 can be formed (step [b]).

More specifically, by cutting the peripheral portion of the raw material polarizing plate 30 while moving the end mill 50 relative to the peripheral portion of the raw material polarizing plate 30, for example, in the directions indicated by the block arrows in FIGS. 3 (a) to 3 (c). As shown in 3 (b) and (c), the step [b] of forming the peripheral edge portion of the polarizing plate 10 other than the recess 11 is performed. In step [b], as shown in FIGS. 3 (b) and 3 (c), a step of cutting so as to chamfer the corners of the raw material polarizing plate 30 to form a rounded corner shape (shape having R). Can be included. By further performing cutting in this step [b], the step [a] of forming the recess 11 can be performed as shown in FIG. 3 (d). The step [a] can include a step of forming the concave portion 11 and cutting to chamfer the corner portion of the concave portion 11 to form a rounded corner shape (shape having R).

The step [a] is a step of cutting a region where the recess 11 is formed in the raw material polarizing plate 30, and the recess 11 is formed by performing this step [a] once or more. The cutting process in the step [a] is performed so that the cutting width per cutting is 150 μm or less. The cutting width is the position of the peripheral edge before cutting (each on the peripheral edge) when the contour of the peripheral edge before cutting and the contour of the peripheral edge after cutting are concentrically overlapped with respect to the raw material polarizing plate 30. The shortest distance between the point) and each position of the peripheral edge after cutting (each point on the peripheral edge). The cutting width may be 140 μm or less, 120 μm or less, or 100 μm or less. The cutting width is usually 10 μm or more, and may be 20 μm or more.

The step [a] may be performed any number of times as long as the cutting width is within the above range. The step [a] is preferably performed twice or more, preferably three times or more, and usually 10 times or less, and five times, from the viewpoint of forming a good cutting end face and efficiently performing the cutting process. The following is preferable. When the step [a] is performed twice or more, the cutting width may be 150 μm or less in each time, and the cutting width in each time may be the same or different. When the step [a] is performed twice or more, for example, a cutting process having a large cutting width may be performed first, and then a cutting process having a small cutting width may be performed.

As described above, in the method for manufacturing the polarizing plate 10, the cutting width per cutting in the cutting process performed to form the concave portion 11 is reduced. As a result, it is possible to prevent the generation of long cracks around the recess 11 due to the condensation heat shock test of the polarizing plate 10. The crack is a crack that penetrates or does not penetrate the outer surface or the thickness direction of the polarizing plate 10, and the cracks are completely separated from each other.

It is presumed that the cracks are generated from the cracks (fine cracks on the surface and inside of the polarizing plate 10) existing on the surface of the polarizing plate 10 and inside the polarizing plate 10 due to the shrinkage of the polarizing plate by the dew condensation heat shock test. Will be done. In particular, in the concave portion 11 of the polarizing plate 10, stress tends to be concentrated due to the shrinkage and expansion of the polarizing plate in the condensation heat shock test, so that it is presumed that long cracks are likely to occur around the concave portion 11 starting from the craze.

From these points, it is considered necessary to suppress the craze generated around the recess 11 of the polarizing plate 10 in order to reduce the occurrence of long cracks due to the condensation heat shock test. It is presumed that the craze is generated by the load applied to the raw material polarizing plate 30 in the punching process, the cutting process, the cutting process, or the like. On the other hand, it is considered that the cutting resistance generated by the cutting process of the raw material polarizing plate 30 can be relatively reduced by reducing the cutting width per cutting process as described above. Further, it is considered that the amount of load accumulated in the polarizing plate due to the cutting process can be relatively reduced by reducing the cutting width per cutting process. From these points, it is presumed that the craze generated around the concave portion 11 of the polarizing plate 10 can be suppressed by performing the cutting process as in the above-mentioned step [a]. As a result, it is considered that the polarizing plate 10 in which the concave portion 11 is formed by reducing the cutting width per cutting can suppress the generation of long cracks due to the condensation heat shock test.

In particular, the polarizing plate 10 having the recess 11 is assumed to be used for a display device of a mobile terminal such as a smartphone or a tablet, and an earpiece, a speaker, a camera lens, various sensors and the like are arranged in the region of the recess 11. .. In mobile terminals such as smartphones and tablets, the frame is being narrowed from the viewpoint of expanding the display area and design. Therefore, even if a crack has a length that is not a problem because it is hidden by the frame in a display device having a relatively wide frame, it has a problem because it adversely affects the display area in a display device with a narrow frame. May become. As described above, the polarizing plate 10 in which the generation of long cracks is suppressed by the condensation heat shock test can be suitably used for mobile terminals such as smartphones and tablets whose frame has been narrowed.

The raw material polarizing plate 30 in which the recess 11 is formed by cutting as shown in FIGS. 3 (a) to 3 (d) is further cut, for example, as shown in FIGS. 4 (a) to 4 (c). , The polarizing plate 10 can be manufactured. As shown in FIG. 4A, rotation is performed on the end face of the raw material polarizing plate 30 with respect to the end portion of the raw material polarizing plate 30 which has not been cut in the steps shown in FIGS. 3A to 3D. The cutting portion 52 of the end mill 50 that rotates about the shaft 51 is brought into contact with the cutting portion 52, and the end mill 50 is relatively moved with respect to the peripheral portion of the raw material polarizing plate 30 in the direction indicated by the block arrow in FIG. 4A. Perform processing. As a result, as shown in FIG. 4B, the step [b] of forming the peripheral edge portion of the polarizing plate 10 other than the recess 11 is performed. As shown in FIG. 4B, the step [b] may include a step of cutting the raw material polarizing plate 30 so as to chamfer the corners to form a rounded corner shape (shape having R). can. This makes it possible to obtain a polarizing plate 10 having a recess 11 formed in the peripheral portion shown in FIG. 1 (FIG. 4 (c)).

The cutting width per cutting in the above-mentioned step [b] is not particularly limited. The cutting width per cutting in the step [b] may be, for example, 150 μm or less, or may be more than 150 μm. The cutting width per cutting in the step [b] may be the same as that of the step [a] performed before or after the step [b].

Step [b] can be performed once or twice or more. The step [b] is usually preferably performed twice or more, preferably 3 times or more, usually 10 times or less, and 5 times or less, from the viewpoint of forming a good cutting end face and efficiently performing the cutting process. Is preferable. The number of times the step [b] is performed may be the same as that of the step [a] performed before or after the step [b].

In the cutting process of the above-mentioned step [A], the relationship between the rotation direction of the end mill 50 and the relative movement direction of the end mill 50 is not particularly limited. 5 (a) and 5 (b) are diagrams illustrating the relationship between the rotation direction and the relative movement direction of the end mill. In the above cutting process, as shown in FIG. 5A, the rotation direction of the end mill 50 (the direction indicated by the line arrow in the figure) at the contact portion between the end face of the raw material polarizing plate 30 and the cutting portion 52 of the end mill 50 is set. It may be a so-called up direction which is the same as the relative movement direction of the end mill 50 with respect to the peripheral edge portion of the raw material polarizing plate 30 (the direction indicated by the block arrow in the figure), or may be the opposite down direction. As shown in FIG. 5B, the down direction is the rotation direction of the end mill 50 (the direction indicated by the line arrow in the figure) at the contact portion between the end face of the raw material polarizing plate 30 and the cutting portion 52 of the end mill 50. The direction opposite to the relative movement direction of the end mill 50 with respect to the peripheral edge of the raw material polarizing plate 30 (the direction indicated by the block arrow in the figure). From the viewpoint of shortening the length of cracks generated around the recess 11, it is preferable to perform cutting in the above step [a] with the rotation direction of the end mill 50 as the up direction.

In the cutting process of the above step [A], the rotation speed of the end mill 50 is not particularly limited, but is usually 500 rpm or more, 1000 rpm or more, 5000 rpm or more, or 10,000 rpm or more. It may be 20000 rpm or more. The rotation speed of the end mill 50 is usually 60,000 rpm or less, may be 55,000 rpm or less, or may be 50,000 rpm or less. When the step [A] includes the step [a] and the step [b], the rotation speed of the end mill 50 may be the same or different from each other in the step [a] and the step [b]. Further, they may be partially different during the steps [a] and [b].

In the cutting process of the above step [A], the relative moving speed (feeding speed) of the end mill 50 with respect to the raw material polarizing plate 30 is not particularly limited, but is usually 100 mm / min or more, and may be 500 m / min or more. It may be 1000 mm / min or more, usually 3000 mm / min or less, 2500 mm / min or less, or 2000 mm / min or less. When the step [A] includes the step [a] and the step [b], the relative movement speed (feed speed) of the end mill 50 with respect to the raw material polarizing plate 30 is the same in the step [a] and the step [b]. It may be different from each other, or may be partially different during the steps [a] and [b].

The above-mentioned step [A] may be performed with one raw material polarizing plate 30, or may be performed by laminating two or more raw material polarizing plates 30. When the raw material polarizing plate 30 is laminated, the number of laminated raw material polarizing plates 30 depends on the thickness of the raw material polarizing plate 30, but can be, for example, 10 or more, 20 or more, or 30 or more. , 40 or more, usually 100 or less, 80 or less, or 60 or less.

The end mills 50 used in the cutting steps shown in FIGS. 3 (a) to 3 (d) and the cutting steps shown in FIGS. 4 (a) to 4 (c) may be the same or different from each other. When different end mills 50 are used, the types of end mills (shape of cutting blade, direction and angle of cutting blade, direction and angle of twist of cutting blade, etc.) may be different from each other. Further, in the cutting steps shown in FIGS. 3 (a) to 3 (d) and the cutting steps shown in FIGS. 4 (a) to 4 (c), the cutting conditions (end mill rotation speed, rotation speed, relative moving speed) in each cutting process , End mill rotation direction, relative movement direction, etc.) may be the same as each other or may be different from each other.

In the method for manufacturing the polarizing plate 10 shown in FIGS. 3 (a) to 3 (d) and FIGS. 4 (a) to 4 (c), in FIGS. 3 and 4, in the counterclockwise direction along the peripheral edge of the raw material polarizing plate 30. A step in which the end mill 50 moves relative to each other to perform cutting (FIGS. 3A to 3D), and a step in which the end mill 50 moves relative to each other clockwise along the peripheral edge of the raw material polarizing plate 30 to perform cutting. (FIGS. 4A to 4C), the polarizing plate 10 is manufactured, but the present invention is not limited to this. For example, the end mill 50 may move relative to each other so as to make one turn counterclockwise or clockwise along the peripheral edge of the raw material polarizing plate 30, and the raw material polarizing plate 30 may be cut. The start position and end position of the cutting process of the raw material polarizing plate 30 are not limited to the positions shown in FIGS. 3 (a) and 3 (d) and the positions shown in FIGS. 4 (a) and 4 (c), and any position can be used. Can be selected.

Further, the peripheral portion of the raw material polarizing plate 30 is divided into two ranges, and cutting is performed by the steps shown in FIGS. 3 (a) to 3 (d) and the steps shown in FIGS. 4 (a) to 4 (c). Not limited to the method, the peripheral portion of the raw material polarizing plate 30 may be divided into arbitrary ranges, and cutting may be performed in any order for each range. In this case as well, the types of end mills 50 used in each process and the cutting conditions in each process may be the same or different from each other. Further, the cutting process in each range may be performed twice or more.

(Polarizer)
FIG. 6 is a schematic cross-sectional view schematically showing an example of a polarizing plate. As shown in FIG. 1, the polarizing plate 10 has a recess 11 on the peripheral edge portion in a plan view, and as shown in FIG. 6, for example, the polarizing plate 10 has protective layers 2 and 3 on both sides of the polarizing element layer 1. The polarizing plate 10 may have only one of the protective layers 2 and 3. The polarizing layer 1 is a polyvinyl alcohol-based resin layer in which the dichroic dye is adsorbed and oriented. The protective layers 2 and 3 may be a layer provided so as to be in direct contact with the polarizing element layer 1, or may be a layer provided via an adhesive layer or an adhesive layer. The polarizing plate 10 has no craze at any position of 30 μm or 50 μm in the plane direction from the edge existing in an arbitrary range of 5 mm in length along the contour of the recess 11.

The edge within the above-mentioned arbitrary range is not particularly limited as long as it is a range along the contour of the concave portion 11 of the polarizing plate 10. It is preferable that the contour of the recess 11 is a linear portion over 5 mm or more. When the concave portion 11 of the polarizing plate 10 includes a linear portion and a curved portion, the edge within the above-mentioned arbitrary range has a length of 5 mm from the side adjacent to (continuously) the curved portion in the linear portion. It is preferable that the edge is present in the range.

Specifically, as shown in FIG. 1, two sides 11a and 11c in which the contours of the recesses 11 of the polarizing plate 10 are provided so as to face each other and each has a linear portion, and the two sides 11a. , 11c is connected and has one side 11b having a linear portion, the position 11ab where one side 11a of the two sides and one side 11b are in contact with each other, and the other side 11c of the two sides. It is considered that the stress by the moist heat heat shock test is likely to be concentrated at the position 11bc where the surface and the one side 11b are in contact with each other and in the vicinity thereof. Therefore, the edge within the above-mentioned arbitrary range exists in a range of a length of 5 mm from the side where one of the two sides 11a and 11c and the one side 11b are in contact with each other in the linear portion of one side 11b. It is preferable to use an edge. The linear portion of one side 11b means that one of the two sides 11a and 11c and one side 11b are in contact with each other when the concave portion 11 has a rounded corner portion as in the polarizing plate 10 shown in FIG. It is a straight part excluding the curved part that constitutes the rounded corner part including the part.

The contour of the recess 11 is the entire peripheral edge of the peripheral portion of the polarizing plate 10 that forms the contour of the recess 11. The boundary between the portion forming the contour of the concave portion 11 and the portion forming the contour of the peripheral portion other than the concave portion 11 is the apex of the corner portion when the boundary is a corner portion, and the boundary has rounded corners. (When the corner has an R shape) is a position where the contour length of the rounded corner portion is bisected. The edge of the concave portion 11 of the polarizing plate 10 refers to the edge of the outermost portion of the end surface (the surface along the thickness direction) of the concave portion 11 of the polarizing plate 10 in the surface direction. The distance in the plane direction from the edge of the recess 11 is a distance in a direction orthogonal to the linear edge in a plan view when the edge existing in the above-mentioned arbitrary range is linear. When the edge existing in the above-mentioned arbitrary range is curved, the distance in the direction orthogonal to the tangent line passing through the position at each position of the curved edge is the distance in the plane direction from the edge of the recess 11. And.

As described above, the craze is a fine crack on the surface or inside of the polarizing plate 10. As will be described later, the polarizing plate 10 may have a layer other than the polarizing layer 1 and the protective layers 2 and 3, but the craze of the polarizing plate 10 is formed on the polarizing layer 1 and the protective layers 2 and 3. It means something that exists. The craze is observed in the cross section of the polarizing plate 10, for example, as shown in FIG. 7 (a). 7 (a) and 7 (b) are views showing images of the cross section of the polarizing plate 10 observed with a scanning laser microscope. FIG. 7A shows an example of an image in the case where a craze is present in the cross section of the polarizing plate 10, and the craze is present in the portion surrounded by the broken line in FIG. 7A. On the other hand, when the craze does not exist in the cross section of the polarizing plate 10, as shown in FIG. 7 (b), the portion shown by the broken line in FIG. 7 (a) is not confirmed.

As described above, the polarizing plate 10 crazes at any position of 30 μm and 50 μm in the plane direction from the edge existing in the arbitrary range in an arbitrary range of 5 mm in length along the contour of the recess 11 described above. Does not exist. Further, the polarizing plate 10 may or may not have crazes at a position 10 μm in the plane direction from the edge existing in an arbitrary range.

Condensation It is presumed that long cracks generated by the heat shock test are likely to occur in the direction of the edge of the recess 11 and in the direction opposite to the direction of the edge, starting from the craze existing in the polarizing plate 10. From this, it is considered that if the craze is present at a position farther from the edge of the recess 11 of the polarizing plate 10 in the plane direction, the length of the crack generated by the condensation heat shock test becomes relatively long. Therefore, as described above, since the polarizing plate 10 does not have crazes at positions 30 μm and 50 μm in the plane direction from the edge of the recess 11, long cracks are generated in the polarizing plate 10 by the condensation heat shock test. It is thought that this can be suppressed. On the other hand, even if the cracks are present at a position of 10 μm in the plane direction from the edge of the concave portion 11 of the polarizing plate 10, the cracks generated by the condensation heat shock test are considered to be short. Therefore, it is considered that the display area of a mobile terminal such as a smartphone or tablet is unlikely to be adversely affected, but it is preferable that the craze does not exist even at a position where the polarizing plate 10 is 10 μm in the plane direction from the edge of the recess 11.

8 (a) and 8 (b) are schematic plan views schematically showing another example of the polarizing plate. The planar view shape of the polarizing plate 10 is not particularly limited. For example, it may be a square shape having a recess 11 on at least one side or a square shape with rounded corners. As shown in FIGS. 1, 8 (a) and 8 (b), a rounded square shape means that one or more of the four corners (for example, all four corners) have a predetermined radius of curvature in the square shape. It has a rounded corner shape. The square shape is a rectangle or a square. The planar view shape of the polarizing plate 10 is not limited to a square shape, and may be a polygon, a circle, an ellipse, or the like other than the square shape.

One or more recesses 11 of the polarizing plate 10 can be provided on the peripheral edge of the polarizing plate 10 in a plan view. When the planar view shape of the polarizing plate 10 is a square shape with rounded corners as shown in FIGS. 1, 8 (a) and 8 (b), it is possible to have one or more recesses 11 on at least one side thereof, for example, short. The recess 11 can be provided on one side of the sides. The recess 11 may have two or more recesses on one side, or may have one or more recesses 11 on each of two or more sides.

The size of the polarizing plate 10 is not particularly limited, but when the polarizing plate 10 is rectangular, for example, the length of the short side can be 30 mm or more and 90 mm or less, and the length of the long side can be 30 mm or more and 170 mm or less. Can be.

The shape of the recess 11 of the polarizing plate 10 is not particularly limited. For example, it may be quadrangular as shown in FIG. 1, U-shaped as shown in FIG. 8 (a), or V-shaped as shown in FIG. 8 (b). good. When the concave portion 11 has a rectangular shape, it is not limited to a rectangular shape and may be a square shape. The corners of the recess may be chamfered and rounded. As shown in FIG. 8B, the top portion (the portion most inserted in the surface direction) of the V-shaped recess 11 may be chamfered. Although not shown, the shape of the concave portion 11 of the polarizing plate 10 may be a trapezoidal shape, an arc shape, or a polygonal shape other than a quadrangle or a triangle. As shown in FIGS. 1, 8 (a) and 8 (b), the shape of the recess 11 may be symmetrical or asymmetrical in the left-right direction in the figure. The contour of the recess 11 may be formed from one of a linear portion and a curved portion, and may include both a linear portion and a curved portion.

As shown in FIGS. 8A and 8B, when the recess 11 has a U-shape and a V-shape, the edge existing in an arbitrary range of length 5 mm along the contour of the recess 11 is the recess 11. It is preferable that it is a part of the linear portion of the above, and it is more preferable that the edge exists in a range of a length of 5 mm from the side adjacent (continuously) to the curved portion in the linear portion. Specifically, in the polarizing plate 10 shown in FIGS. 8A and 8B, a curved portion is formed in a linear portion adjacent to the curved portion including the top of the recess 11 (the portion most inserted in the plane direction). It can be an edge existing in a range of 5 mm in length from the side adjacent to (for example, a portion surrounded by a broken line in the figure).

The corners provided inside the recess 11 of the polarizing plate 10 are preferably chamfered and have a rounded corner shape (shape having R). The corner portion provided inside the concave portion 11 is a corner portion existing in the corner portion provided in the concave portion 11 other than the boundary portion between the contour of the concave portion 11 and the peripheral portion other than the concave portion 11. Specifically, for example, in the polarizing plate 10 shown in FIG. 1, it is preferable that the positions 11ab and 11bc have rounded corners. By forming the corners inside the concave portion 11 into a rounded corner shape, it becomes easy to suppress the occurrence of cracks due to the condensation heat shock test in the portion. The corner portion of the boundary portion between the contour of the recess 11 and the peripheral edge portion other than the recess 11 may also be chamfered and have a rounded corner shape (shape having R).

The size of the recess 11 of the polarizing plate 10 is not particularly limited, but the maximum length in the direction along the side where the recess 11 is formed (distance indicated by w in FIGS. 1, 8 (a) and 8 (b)) is For example, it can be 3 mm or more and 160 mm or less. The maximum depth of the recess 11 (the direction orthogonal to the side where the recess 11 is formed, the distance indicated by d in FIGS. 1, 8 (a) and 8 (b)) shall be, for example, 0.5 mm or more and 160 mm or less. Can be done.

As described above, the polarizing plate 10 has protective layers 2 and 3 on one side or both sides of the polarizing layer 1. When the polarizing plate 10 has protective layers 2 and 3 on both sides of the polarizing layer 1, at the end thereof, the polarizing layer 1 is placed between the two protective layers 2 and 3 provided on both sides of the polarizing layer 1. (FIG. 6), but they may be directly overlapped without interposing the polarizing element layer 1, or the two protective layers 2 and 3 may be fused.

The polarizing plate 10 may be further provided with an adhesive layer on the side of the protective layers 2 and 3 opposite to the polarizing layer 1, and a release film is further provided on the side of the adhesive layer opposite to the protective layers 2 and 3. May be provided. The pressure-sensitive adhesive layer and the release film can be provided on one side or both sides of the polarizing plate 10. The pressure-sensitive adhesive layer can be used, for example, to bond the polarizing plate 10 to an image display element included in a display device such as a liquid crystal display device or an organic EL display device. The release film is for covering and protecting the pressure-sensitive adhesive layer, and can be peeled off from the pressure-sensitive adhesive layer.

The polarizing plate 10 may further include an optical functional layer on the side of the protective layers 2 and 3 opposite to the polarizing layer 1. The optical functional layer can be provided on one side or both sides of the polarizing plate 10. When the polarizing plate 10 has the above-mentioned pressure-sensitive adhesive layer, the optical functional layer may be provided on the side opposite to the side where the pressure-sensitive adhesive layer of the polarizing plate 10 is provided, and is between the polarizing plate 10 and the pressure-sensitive adhesive layer. It may be provided in.

The polarizing plate 10 may be provided with a protective film on the side of the protective layers 2 and 3 opposite to the polarizing layer 1. The protective film is provided in order to prevent scratches, stains, and the like from being generated on the surface of the polarizing plate 10 during the production of a product using the polarizing plate 10, the production and transportation of the polarizing plate 10. When the polarizing plate 10 has an optical functional layer, the protective film is provided on the side opposite to the polarizing element layer 1 of the optical functional layer. The protective film can be peeled off from the surface of the polarizing plate 10.

The polarizing plate 10 can be used by being laminated on an image display element of a display device. Examples of the display device include a liquid crystal display device, an organic EL display device, and the like. When the display device is a liquid crystal display device, the polarizing plate 10 may be laminated on one surface of a liquid crystal panel having a liquid crystal cell, or the polarizing plate 10 may be laminated on both sides of the liquid crystal panel. When the polarizing plate 10 is applied to a display device, it is preferable that the polarizing plate 10 is laminated on an image display element via an adhesive layer or an adhesive layer.

(Raw material polarizing plate)
The raw material polarizing plate 30 is used to obtain the polarizing plate 10. As described above, the raw material polarizing plate 30 is preferably cut into a predetermined shape and size by punching, cutting, or the like. The polarizing plate 10 can be obtained, for example, by subjecting such a raw material polarizing plate 30 to a cutting process according to the above-mentioned step [A].

The raw material polarizing plate 30 has a protective layer on one side or both sides of the polarizing element layer. The polarizing layer is a polyvinyl alcohol-based resin layer in which the dichroic dye is adsorbed and oriented. The protective layer may be a layer provided so as to be in direct contact with the polarizing element layer, or may be a layer provided via an adhesive layer or an adhesive layer. Usually, the raw material polarizing plate 30 preferably has the same layer structure as the polarizing plate 10 in order to obtain the polarizing plate 10 by cutting the raw material polarizing plate 30. Therefore, the raw material polarizing plate 30 may be provided with the above-mentioned pressure-sensitive adhesive layer, optical functional layer, protective film, etc., which may be provided by the polarizing plate 10, on one side or both sides thereof. When the raw material polarizing plate 30 includes the pressure-sensitive adhesive layer, it is preferable that the release film is provided on the side opposite to the polarizing layer of the pressure-sensitive adhesive layer.

The plan view shape of the raw material polarizing plate 30 is not particularly limited, but it is preferable that the shape is substantially similar to the shape of the polarizing plate 10 manufactured by using the raw material polarizing plate 30. Since the polarizing plate 10 has a recess 11, it is preferable that the raw material polarizing plate 30 also has a concave notch 31, for example, as shown in FIG. 3 (a). The corners of the raw material polarizing plate 30 and the corners of the notch 31 may not be chamfered.

The raw material polarizing plate 30 is obtained, for example, by obtaining a long strip-shaped laminate in which a long strip-shaped polarizing layer and a long strip-shaped protective layer are bonded, and from this laminate, the above-mentioned step [A]. It can be obtained by cutting out to a size that is easy to cut with. The raw material polarizing plate 30 can be cut out by punching or cutting. A cutting tool or a laser can be used for the cutting process. When the raw material polarizing plate 30 has a concave notch portion 31, the notch portion 31 may be formed in the laminate cut out from the above-mentioned laminate to a predetermined size by punching or cutting. The raw material polarizing plate 30 having the notch portion 31 may be obtained by punching or cutting the laminate.

Hereinafter, each layer used for the polarizing plate 10 and the raw material polarizing plate will be described in detail.
(Polarizer layer)
The polarizing layer 1 is preferably a film-like polyvinyl alcohol-based resin layer (PVA film) in which the dichroic dye is adsorbed and oriented, which is produced by steps such as stretching, dyeing, and crosslinking. The polarizing element layer 1 can be produced by a known method, and can be produced, for example, by the following procedure.

First, the PVA film is stretched in the uniaxial direction or the biaxial direction. The bicolor ratio of the polarizing element layer 1 stretched in the uniaxial direction tends to be high. Following stretching, the PVA film is dyed with iodine, a dichroic dye (polyiodine) or an organic dye using a stain. The staining solution may contain boric acid, zinc sulfate, or zinc chloride. The PVA film may be washed with water before dyeing. By washing with water, stains and anti-blocking agents can be removed from the surface of the PVA film. Further, as a result of swelling of the PVA film by washing with water, it is possible to suppress the occurrence of dyeing spots (non-uniform dyeing). The dyed PVA film is treated with a solution of cross-linking agent (eg, an aqueous solution of boric acid) for cross-linking. After treatment with a cross-linking agent, the PVA film is washed with water and then dried. From the above, the polarizing element layer 1 can be obtained.

The polyvinyl alcohol (PVA) -based resin is obtained by saponifying a polyvinyl acetate-based resin. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, or a copolymer of vinyl acetate and another monomer (for example, an ethylene-vinyl acetate copolymer). Be done. Examples of other monomers copolymerizing with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and 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.

The PVA film used above may be dyed before stretching or may be stretched in a dyeing solution. The length of the stretched polarizing element layer 1 can be, for example, 3 to 7 times the length before stretching.

The thickness of the polarizing layer 1 can be, for example, 1 μm or more, may be 3 μm or more, and is usually 50 μm or less, and may be 15 μm or less. The smaller the thickness of the polarizing element layer 1, the more the contraction or expansion of the polarizing element layer 1 itself due to the temperature change is suppressed, and the change in the dimensions of the polarizing element layer 1 itself is suppressed. As a result, stress due to contraction and expansion is unlikely to act on the polarizing element layer 1, and cracks generated in the polarizing element layer 1 by the condensation heat shock test are likely to be suppressed.

(Protective layer)
The protective layers 2 and 3 can be configured by using an optically transparent thermoplastic resin having translucency. Examples of the resin constituting the protective layers 2 and 3 include a chain polyolefin resin, a cyclic olefin polymer resin (COP resin), a cellulose ester resin, a polyester resin, a polycarbonate resin, a (meth) acrylic resin, and a polystyrene. Examples thereof include based resins, mixtures thereof, and copolymers thereof. "(Meta) Acrylic" means at least one selected from the group consisting of acrylics and methacrylics.

Examples of the chain polyolefin resin include homopolymers of chain olefins such as polyethylene resin and polypropylene resin. The chain polyolefin resin may be a copolymer composed of two or more kinds of chain olefins.

Examples of the cyclic olefin polymer-based resin (cyclic polyolefin-based resin) include a ring-opening (co) polymer of cyclic olefin and an addition polymer of cyclic olefin. The cyclic olefin polymer-based resin may be, for example, a copolymer of a cyclic olefin and a chain olefin (for example, a random copolymer). 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 above 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.

Examples of the cellulose ester resin include cellulose triacetate (triacetyl cellulose (TAC)), cellulose diacetate, cellulose tripropionate or cellulose dipropionate, and a copolymer thereof thereof may be used. The cellulose ester resin may be a cellulose ester resin in which a part of the hydroxyl group is modified with another substituent.

Examples of the polyester-based resin include polyester-based resins other than the cellulose ester-based resin. Examples of such a polyester resin include a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. Examples of the polyvalent carboxylic acid or a derivative thereof include a dicarboxylic acid or a derivative thereof, and examples thereof include terephthalic acid, isophthalic acid, dimethylterephthalate, and dimethyl naphthalenedicarboxylate. Examples of the polyhydric alcohol include diols, such as ethylene glycol, propanediol, butanediol, neopentyl glycol, or cyclohexanedimethanol.

Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethylterephthalate, and polycyclohexanedimethylnaphthalate. Be done.

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

Examples of the (meth) acrylic resin include poly (meth) acrylic acid ester (for example, 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); methyl methacrylate and alicyclic charcoal Examples thereof include a polymer with a compound having a hydrogen group (for example, a methyl methacrylate-cyclohexyl methacrylate copolymer, a methyl methacrylate- (meth) norbornyl acrylate copolymer, etc.).

The glass transition temperature of the resin constituting the protective layers 2 and 3 is preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and more preferably 200 ° C. or lower, and 150 ° C. or lower. Is more preferable. Since the glass transition temperature of the protective layers 2 and 3 is within the above range, the ends of the protective layers 2 and 3 provided on both sides of the polarizing element layer 1 are mutually exchanged by the heat generated by the cutting process of the raw material polarizing plate 30. It can be in a fused state.

The protective layers 2 and 3 may contain at least one additive selected from the group consisting of lubricants, plasticizers, dispersants, heat stabilizers, UV absorbers, infrared absorbers, antistatic agents, and antioxidants. ..

When the polarizing plate 10 has the protective layers 2 and 3 on both sides of the polarizing element layer 1, the compositions of the two protective layers 2 and 3 may be the same or different from each other. Since the protective layers 2 and 3 contain a cellulose ester resin such as triacetyl cellulose (TAC), it becomes easy to suppress long cracks generated around the recess 11 in the condensation heat shock test. On the other hand, when the protective layers 2 and 3 contain a cyclic olefin polymer resin (COP resin), the cracks generated around the recess 11 tend to be long and the number of cracks tends to increase in the condensation heat shock test. .. The above-mentioned method for manufacturing a polarizing plate is suitable because long cracks can be suppressed even when a polarizing plate having protective layers 2 and 3 containing a COP-based resin is manufactured.

The thickness of the protective layers 2 and 3 may be, for example, 5 μm or more and may be 10 μm or more, and usually 90 μm or less and may be 60 μm or less. When the polarizing plate 10 has the protective layers 2 and 3 on both surfaces of the polarizing element layer 1, the thicknesses of the two protective layers 2 and 3 may be the same or different from each other.

The protective layers 2 and 3 may be a film having an optical function. Examples of the film having an optical function include a retardation film and a luminance improving film. The retardation film can be obtained, for example, by stretching a film made of the above-mentioned thermoplastic resin or forming a liquid crystal layer or the like on the film.

The protective layers 2 and 3 can be laminated on the polarizing element layer 1 via an adhesive layer. Examples of the adhesive constituting the adhesive layer include water-based adhesives such as polyvinyl alcohol and active energy ray-curable resins described later.

The active energy ray curable resin is a resin that cures when irradiated with active energy rays. Examples of the active energy ray include ultraviolet rays, visible light, electron beams, and X-rays. For example, the active energy ray curable resin may be an ultraviolet curable resin.

The active energy ray-curable resin may contain one kind of resin or may contain a plurality of kinds of resins. For example, the active energy ray-curable resin may contain a cationically polymerizable curable compound or a radically polymerizable curable compound. The active energy ray-curable resin may contain a cationic polymerization initiator or a radical polymerization initiator for initiating the curing reaction of the curable compound.

Examples of the cationically polymerizable curable compound include an epoxy-based compound (a compound having at least one epoxy group in the molecule) and an oxetane-based compound (a compound having at least one oxetane ring in the molecule). Examples of the radically polymerizable curable compound include (meth) acrylic compounds (compounds having at least one (meth) acryloyloxy group in the molecule). Examples of the radically polymerizable curable compound include vinyl compounds having a radically polymerizable double bond.

The active energy ray-curable resin may be a cationic polymerization accelerator, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow conditioner, a plasticizer, and a defoaming agent, if necessary. It may contain an agent, an antistatic agent, a leveling agent, a solvent and the like.

(Adhesive layer)
The pressure-sensitive adhesive layer develops adhesiveness by sticking itself to an adherend, and can be formed by a pressure-sensitive adhesive, which is a so-called pressure-sensitive adhesive. As the pressure-sensitive adhesive, known ones can be used, and examples thereof include an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and a urethane-based pressure-sensitive adhesive. The thickness of the pressure-sensitive adhesive layer can be, for example, 2 μm or more and 100 μm or less.

(Release film)
As described above, the release film is used for the purpose of covering and protecting the pressure-sensitive adhesive layer. The release film is peeled off when the polarizing plate 10 is attached to an image display element or the like of a display device. As the release film, a resin film having a mold release treatment on the side in contact with the pressure-sensitive adhesive layer can be used. Examples of the resin film include a film using a resin exemplified as the resin constituting the protective layers 2 and 3. Examples of the mold release treatment include silicone coating and the like. The thickness of the release film can be, for example, 10 μm or more and 100 μm or less.

(Optical functional layer)
The optical functional layer is not particularly limited as long as it is a layer having an optical function, and may be a film. Examples of the optical functional layer include a retardation film, a reflective polarizing film, a film with an antiglare function, a film with a surface antireflection function, a reflective film, a transflective reflective film, a viewing angle compensating film, a window film, and an antistatic layer. Examples thereof include a hard coat layer, an optical compensation layer, a touch sensor layer, and an antifouling layer. One or more of these can be used as the optical functional layer.

(Protect film)
As described above, the protective film is used for the purpose of protecting the surface of the polarizing plate 10. The protective film may be a base film having an adhesive layer, or may be a self-adhesive film. Examples of the resin used for the base film of the protective film include the resin used for the above-mentioned protective layers 2 and 3, and examples of the adhesive layer include the above-mentioned adhesive. The self-adhesive film can be formed by using, for example, a polypropylene-based resin, a polyethylene-based resin, or the like.

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

[Condensation heat shock test]
Using the polarizing plates obtained in Examples and Comparative Examples, a step of performing the following steps 1 to 3 in this order was set as one cycle, and a condensation heat shock test was carried out in which this was continuously repeated for 10 cycles.
・ Step 1:
The polarizing plate is held at a temperature of −40 ° C. and a relative humidity of 11% RH for 30 minutes.
・ Step 2:
The polarizing plate obtained in step 1 is held in an environment of a temperature of 23 ° C. and a relative humidity of 9% RH for 5 minutes.
・ Step 3:
The polarizing plate subjected to step 2 is held in an environment of a temperature of 85 ° C. and a relative humidity of 7% RH for 30 minutes.

With respect to the polarizing plate subjected to the above-mentioned condensation heat shock test, the periphery of the recess was observed with an optical microscope in a plan view. With respect to the polarizing plates obtained in Examples and Comparative Examples, among the cracks generated near the positions 11ab and 11bc of the recess 11 shown in FIG. 1, the one having the longest length in the long side direction of the polarizing plate was measured. This was taken as the length of the crack in the curved portion of the recess. Further, in Example 2 and Comparative Example 3, in the linear portion of the side 11b of the recess 11 shown in FIG. 1, the edge and the side existing in a length range of 5 mm from the side where the side 11a and the side 11b are in contact with each other. The length in the long side direction of the polarizing plate of the crack generated near the edge existing in the range of 5 mm from the side where 11b and the side 11c are in contact with each other was also measured, and among the measured cracks, the length in the long side direction of the polarizing plate was measured. The one with the longest length was defined as the crack length in the linear portion of the recess.

[Example 1] (Comparative example)
A polyvinyl alcohol film was stretched and dyed to form one surface of an 8 μm-thick stator layer using a polyvinyl alcohol-based adhesive (water-based adhesive) and a 52 μm-thick cyclic olefin polymer-based resin. The protective layer was pasted together. A protective layer formed of a cyclic olefin polymer resin having a thickness of 21 μm is attached to the other surface of the polarizing layer via a UV curable epoxy resin, and the UV curable epoxy resin is irradiated with ultraviolet rays. By curing, a polarizing layer and a protective layer having a thickness of 21 μm were laminated. A protective film (thickness 58 μm) having an adhesive layer formed on a base film is attached onto a protective layer having a thickness of 52 μm, and an adhesive layer having a thickness of 20 μm and a release film (thickness 38 μm) are attached to the protective layer having a thickness of 21 μm. ) Was laminated in this order to obtain a rectangular laminated body. In this laminated body, the thickness of the laminated structure from the protective layer having a thickness of 52 μm to the adhesive layer is 102 μm, and a protective film having a thickness of 58 μm is formed on one surface of the laminated structure and a release film having a thickness of 38 μm is formed on the other surface. Each was laminated. In the obtained laminate, the protective layer having a thickness of 21 μm (a protective layer having a thickness of 21 μm formed by using a cyclic olefin polymer resin) bonded to the polarizing layer and the other side is UV curable. It was adhered via an adhesive layer (thickness 1 μm) which was a cured product of the epoxy resin. The obtained laminate was punched using a pinnacle blade to produce 47 raw material polarizing plates having the shape shown in FIG. 3 (a).

Forty-seven raw material polarizing plates were laminated so that the release film side of the above-mentioned raw material polarizing plate was on the lower side, and the raw material polarizing plate was placed on the mounting table of the cutting apparatus and fixed to the mounting table by a clamp. The end face (DXL-4, manufactured by NS TOOL Co., Ltd., diameter: 4 mm, right blade, cutting angle β: 65 [°]) attached to the cutting device is rotated, and the end face of the raw material polarizing plate on which the cutting parts of the end mill are laminated ( The cutting process was performed three times while the end mill was relatively moved with respect to the raw material polarizing plate in a plan view by contacting the surface along the stacking direction. In each cutting process, the cutting width was 100 μm, the rotation speed of the end mill was 30,000 rpm, the feed rate (relative moving speed) of the end mill was 1000 mm / min, and the cutting process was performed in the up direction.

By the above cutting process, a rectangular polarizing plate having a rectangular recess was obtained as shown in FIG. The length of the short side of the polarizing plate was 70 mm, and the length of the long side was 140 mm. The length of the recess in the short side direction (distance of the portion indicated by w in FIG. 1) was 30 mm, and the length in the long side direction (distance of the portion indicated by d in FIG. 1) was 5 mm. The obtained polarizing plate was subjected to a condensation heat shock test, and the crack length in the curved portion of the recess was measured. The results are shown in Table 1.

[Comparative Example 1]
A polarizing plate was obtained in the same manner as in Example 1 except that the cutting process was performed twice and the cutting width at each time was as shown in Table 1. The obtained polarizing plate was subjected to a condensation heat shock test, and the crack length in the curved portion of the recess was measured. The results are shown in Table 1.

[Example 2]
A polarizing plate was obtained in the same manner as in Example 1 except that the cutting process was performed once and the cutting width was shown in Table 2. In the linear portion of the concave portion of the polarizing plate obtained above, the polarizing plate was cut out so that the range of the length of 5 mm from the side of the side 11b in contact with the side 11a became one side, and used as a measurement sample. The end face (the surface along the thickness direction) of the one side of the cut-out measurement sample is shaved using a microtome, and the cross section at the position of 10 μm, the position of 30 μm, and the position of 50 μm in the face direction from the edge of the end face is a scanning type. The presence or absence of craze was confirmed by observing with a laser microscope (observation magnification: 100 times). The results are shown in Table 2.

In addition, the obtained polarizing plate was subjected to a dew condensation heat shock test, and the crack length in the curved portion of the recess and the crack length in the linear portion were measured. The results are shown in Table 2.

[Comparative Example 2]
With respect to the raw material polarizing plate obtained in Example 1, the presence or absence of craze was confirmed by the same procedure as in Example 2. In addition, a condensation heat shock test was performed using the raw material polarizing plate obtained in Example 1, and the crack length in the curved portion of the recess was measured. The results are shown in Tables 1 and 2.

[Comparative Example 3]
A polarizing plate was obtained in the same manner as in Example 2 except that the cutting width was shown in Table 2. With respect to the obtained polarizing plate, the presence or absence of craze was confirmed by the same procedure as in Example 2. In addition, the obtained polarizing plate was subjected to a dew condensation heat shock test, and the crack length in the curved portion of the recess and the crack length in the linear portion were measured. The results are shown in Table 2.

1 Polarizer layer, 2 Protective layer, 3 Protective layer, 10 polarizing plate, 11 recess, 11a, 11b, 11c side, 11ab, 11bc position, 30 raw material polarizing plate, 31 notch, 50 end mill, 51 rotation axis, 52 Cutting part, 52a Cutting blade.

Claims (7)

A method for manufacturing a polarizing plate having a recess in the peripheral portion in a plan view.
A step of preparing a raw material polarizing plate having a protective layer on one or both sides of a polarizing element layer and having a notch formed in a peripheral portion.
The step [a] of forming the concave portion of the polarizing plate by performing a single cutting process so as to form the concave portion while moving the end mill relative to the notch portion of the raw material polarizing plate . Including
The cutting in the step [a] is Ri cutting der performed as cutting width is 150μm or less,
The end mill is provided with a cutting portion having a cutting blade on the outer peripheral surface.
In the step [a], the manufacturing of a polarizing plate in which the rotation direction of the end mill at the contact portion between the end surface of the peripheral edge portion of the raw material polarizing plate and the cutting portion of the end mill is the same as the direction of the relative movement. Method. The raw polarizing plate, having the cutout portion of the concave shape in a region where the recess is formed, the manufacturing method of the polarizing plate according to claim 1. The method for manufacturing a polarizing plate according to claim 1 or 2, wherein the notch is formed by punching. Further, claims 1 to 3 include a step [b] of performing a cutting process so as to form a peripheral portion of the polarizing plate other than the concave portion while moving the end mill relative to the peripheral portion of the raw material polarizing plate. The method for manufacturing a polarizing plate according to any one of the above items. The method for manufacturing a polarizing plate according to claim 4, wherein the step [a] and the step [b] are continuously performed. The method for producing a polarizing plate according to any one of claims 1 to 5, wherein the polarizing layer is a polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and oriented. Any of claims 1 to 6, wherein the cutting angle β, which is an angle formed by the direction d1 in which the cutting blade of the end mill extends and the direction d2 perpendicular to the rotation axis of the end mill, is 30 ° or more and 70 ° or less. The method for manufacturing a polarizing plate according to item 1.

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