Method for manufacturing polarizing plate and polarizing plate

Abstract

The present invention provides a method for manufacturing a polarizer and a polarizer, which can suppress the occurrence of long cracks around a concave portion due to a condensation heat shock test. The method for manufacturing a polarizer having a concave portion at a peripheral portion when viewed from above includes the following steps: a step of preparing a raw polarizer having a protective layer on one or both sides of a polarizing element layer; and a step [a] of performing cutting processing while moving an end mill relative to the peripheral portion of the raw polarizer to form the concave portion. The cutting processing in step [a] is cutting processing performed so that the cutting width becomes less than 150 μm.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a polarizing plate and the polarizing plate. Background Art

[0002] Polarizing plates are used as one of the optical components constituting image display devices such as liquid crystal display devices. Image display devices are also used in portable terminals such as smartphones and tablet computers, and it is known that polarizing plates are also incorporated in such portable terminals.

[0003] In portable terminals such as smart phones and tablet computers, a shape is sometimes made to form a concave portion on the periphery of a display (display unit). In a display having a concave portion as described above, a polarizer having a concave portion that matches the shape of the display is used (e.g., Patent Documents 1, 2, etc.). As a method for obtaining a polarizer having a concave portion, it is known to use a cutting blade to perform punching to form a concave portion on a raw material polarizer, a method of performing cutting processing on the end face of a raw material polarizer to form a concave portion, etc. (e.g., Patent Document 2, etc.).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-25630

[0007] Patent Document 2: JP Patent Publication No. 2018-12182

[0008] The cutting process of the end face of the raw material polarizing plate is usually performed two or more times. In this case, rough cutting is first performed with a relatively large cutting width, and then finishing cutting is performed with a relatively small cutting width.

[0009] In the case of implementing the above-mentioned cutting process to manufacture a polarizer with a concave portion, it is found that there is a situation where a long crack is generated around the concave portion due to the condensation thermal shock test of the polarizer. In portable terminals such as smart phones and tablet computers, narrow frames are sometimes promoted from the perspective of expanding the display area and design. In such a portable terminal that has achieved narrow frames, it is difficult to hide long cracks through the frame, so sometimes it causes problems such as poor display. Summary of the invention

[0010] An object of the present invention is to provide a method for producing a polarizing plate and a polarizing plate capable of suppressing the occurrence of long cracks around recessed portions due to a condensation thermal shock test.

[0011] The present invention provides the following method for producing a polarizing plate and a polarizing plate.

[0012] [1] A method for manufacturing a polarizer is a method for manufacturing a polarizer having a concave portion in a peripheral portion when viewed from above, comprising the following steps: a step of preparing a raw polarizer having a protective layer on one or both sides of a polarizing element layer; and a step [a] of performing a cutting process while moving an end mill relative to the peripheral portion of the raw polarizer to form the concave portion, wherein the cutting process in the step [a] is a cutting process performed so that the cutting width becomes less than 150 μm.

[0013] [2] In the method for producing a polarizing plate according to [1], the raw polarizing plate has a concave notch in a region where the concave portion is to be formed.

[0014] [3] In the method for producing a polarizing plate according to [1] or [2], the step [a] is performed two or more times.

[0015] [4] The method for manufacturing a polarizing plate according to any one of [1] to [3], further comprising: performing a cutting process to form the peripheral portion of the polarizing plate other than the recessed portion while moving the end mill relative to the peripheral portion of the raw polarizing plate [b].

[0016] [5] In the method for manufacturing a diaphragm according to [4], the step [a] and the step [b] are performed continuously.

[0017] [6] In the method for producing a polarizing plate according to any one of [1] to [5], the polarizing element layer is a polyvinyl alcohol-based resin layer to which a dichroic dye is adsorbed and oriented.

[0018] [7] A polarizing plate having a concave portion in the peripheral portion when viewed from above, wherein the polarizing plate has a protective layer on one or both sides of a polarizing element layer, and there are no silver streaks at a position of 30 μm and a position of 50 μm in the plane direction from an edge existing in any range of a length of 5 mm along the contour of the concave portion.

[0019] [8] In the polarizing plate described in [7], further, silver streaks exist or do not exist at a position 10 μm in the plane direction from the edge existing in the arbitrary range.

[0020] [9] In the polarizing plate described in [7] or [8], the contour of the recess has a curved portion and a straight portion, and the edge existing in the arbitrary range is an edge in the straight portion that exists in a range of 5 mm in length from a side adjacent to the curved portion.

[0021]

[10] In the polarizing plate described in any one of [7] to [9], the contour of the recess includes: two sides that are arranged opposite to each other and each has a straight line portion; and one side that connects the two sides and has a straight line portion, and the edge existing in the arbitrary range is an edge in the straight line portion of the one side that exists in a range of 5 mm in length from the side where the one side is in contact with one of the two sides.

[0022]

[11] In the polarizing plate according to any one of [7] to

[10] , the polarizing element layer is a polyvinyl alcohol-based resin layer to which a dichroic dye is adsorbed and oriented.

[0023] According to the present invention, it is possible to provide a polarizing plate capable of suppressing the occurrence of long cracks around the concave portions due to a condensation thermal shock test. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic plan view schematically showing an example of the polarizing plate of the present invention.

[0025] Figure 2 This is a schematic front view schematically showing an example of an end mill used in the method for producing a polarizing plate of the present invention.

[0026] Figure 3 (a) to (d) are schematic top views schematically showing an example of the method for producing the polarizing plate of the present invention.

[0027] Figure 4 (a) to (c) are schematic top views schematically showing an example of the method for producing the polarizing plate of the present invention.

[0028] Figure 5 (a) and (b) are explanatory diagrams for explaining the relationship between the rotation direction and the movement direction of the end mill.

[0029] Figure 6 This is a schematic cross-sectional view schematically showing an example of the polarizing plate of the present invention.

[0030] Figure 7 (a) and (b) schematically show images of a cross section of a polarizing plate observed with a scanning laser microscope.

[0031] Figure 8 (a) and (b) are schematic plan views schematically showing another example of the polarizing plate of the present invention.

[0032] Description of Reference Numerals

[0033] 1 polarizing element layer,

[0034] 2 protective layers,

[0035] 3 protective layers,

[0036] 10 polarizing film,

[0037] 11 concave part,

[0038] 11a, 11b, 11c Edge,

[0039] 11ab, 11bc position,

[0040] 30 raw polarizer,

[0041] 31 Notch,

[0042] 50 End mills,

[0043] 51 Rotation axis,

[0044] 52 Cutting part,

[0045] 52a Cutting edge. DETAILED DESCRIPTION

[0046] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[0047] (Method for producing polarizing plate)

[0048] Figure 1 Schematic diagram of an example of a polarizing plate according to the present embodiment. Figure 1 As shown in FIG. 1 , a method for manufacturing a polarizing plate 10 having a concave portion 11 at a peripheral portion when viewed from above is provided. The method for manufacturing the polarizing plate 10 includes: a step of preparing a raw polarizing plate 30 having a protective layer on one or both sides of a polarizing element layer; and a step [a] of performing a cutting process to form the concave portion 11 while moving an end mill 50 relative to the peripheral portion of the raw polarizing plate 30. The cutting process in step [a] is a cutting process performed so that the cutting width becomes less than 150 μm. The cutting process performed in the method for manufacturing the polarizing plate 10 also includes a grinding process.

[0049] Figure 2 1 is a schematic front view schematically showing an example of an end mill used in the 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. Figure 2 As shown in FIG. 1 , a cutting portion 52 having a cutting edge 52a on the outer peripheral surface is provided on one front end side of a tool body having a rotating shaft 51. Figure 2In the end mill 50 shown, the cutting edge 52a is shown as a right-hand cutting edge, but the present invention is not limited thereto. For example, the cutting edge 52a may be a left-hand cutting edge, and the spiral direction of the cutting edge may be a right-hand spiral or a left-hand spiral.

[0050] The cutting angle β of the end mill 50 is, for example, 30° or more, 40° or more, or 45° or more, and is usually 70° or less, or 65° or less. If the helix angle of the end mill 50 is α[°], the cutting angle β[°] of the end mill 50 is represented by the following formula:

[0051] β=90°-α

[0052] The helix angle α is Figure 2 As shown in FIG. 1 , it is the angle between the direction d1 in which the cutting edge 52a extends on the outer peripheral surface of the end mill 50 and the rotation axis 51. In other words, the cutting angle β is as follows: Figure 2 As shown, it is an angle formed by a direction d1 in which the cutting edge 52 a extends and a direction d2 perpendicular to the rotation axis 51 .

[0053] The diameter φ of the end mill 50 (the maximum diameter drawn by the rotation of the cutting edge) is, for example, 3 mm or more, or 5 mm or more, or 30 mm or less, or 10 mm or less, or 6 mm or less.

[0054] In the method of manufacturing the polarizer 10 by cutting the raw polarizer 30 using the above-mentioned end mill 50, for example, the raw polarizer 30 placed on the mounting table of the cutting device is fixed with a fixture such as a clamp, and the end mill 50 or the mounting table is moved, thereby performing the cutting process while the end mill 50 is relatively moved relative to the peripheral portion of the raw polarizer 30. The relative movement of the end mill 50 with respect to the peripheral portion of the raw polarizer 30 can be, for example, as follows: Figure 3 (a) to (d) and Figure 4 The process is performed as shown in (a) to (c). Figure 3 (a) to (d) and Figure 4 (a) to (c) are schematic top views schematically showing an example of a method for producing a polarizing plate.

[0055] In the method for manufacturing the polarizing plate 10, first, Figure 3 As shown in (a) of FIG. 1 , a process is performed to prepare a raw material polarizing plate 30 cut into a given shape and size. Figure 3(a) shows a rectangular raw polarizer 30 having a concave notch 31 formed on one side. For example, the raw polarizer 30 can be obtained by further performing punching, cutting, etc. on one side of a cut piece cut into a rectangular shape by punching, cutting, etc. to form the notch 31. The raw polarizer 30 can be cut into a shape having the notch 31 by a single punching process or a single cutting process.

[0056] Next, a step of performing cutting while moving the end mill 50 relative to the peripheral portion of the raw polarizer 30 is performed (hereinafter sometimes referred to as step [A]). The cutting in step [a] can be performed by making the cutting portion 52 of the end mill 50 rotating around the rotation axis 51 contact the end face of the raw polarizer 30. The end face of the raw polarizer 30 is a surface along the thickness direction (direction orthogonal to the surface direction) of the raw polarizer 30. By performing step [A], the concave portion 11 of the polarizer 10 can be formed in the area of ​​the notch portion 31 of the raw polarizer 30 (step [a]), and the peripheral portion other than the concave portion 11 of the polarizer 10 can be formed in the area other than the notch portion 31 (step [b]).

[0057] More specifically, the end mill 50 is moved toward the peripheral edge of the raw material polarizing plate 30, for example Figure 3 The cutting process is performed while moving relatively in the direction indicated by the block arrows in (a) to (c). Figure 3 As shown in (b) and (c) of FIG. 1 , a step [b] of forming the peripheral portion of the polarizing plate 10 other than the recessed portion 11 is performed. Step [b] Figure 3 As shown in (b) and (c) of FIG. 1 , the process of performing cutting to chamfer the corners of the raw material polarizer 30 to form a rounded shape (having an R shape) can be included. By further performing cutting in succession with the step [b], the process of Figure 3 The step [a] of forming the recessed portion 11 is performed as shown in (d). The step [a] may include the steps of forming the recessed portion 11 and performing cutting so as to chamfer the corners of the recessed portion 11 to form a rounded shape (a shape having an R).

[0058] Step [a] is a step of cutting the area of ​​the raw polarizer 30 where the recess 11 is to be formed, and the recess 11 is formed by performing this step [a] more than once. The cutting process in step [a] is performed so that the cutting width of each time becomes less than 150 μm. The cutting width is the shortest distance between each position of the peripheral portion before cutting (each point on the peripheral portion) and each position of the peripheral portion after cutting (each point on the peripheral portion) when the contour of the peripheral portion before cutting and the contour of the peripheral portion after cutting coincide concentrically with each other with respect to the raw polarizer 30. The cutting width can be less than 140 μm, less than 120 μm, or less than 100 μm. The cutting width is usually more than 10 μm, or more than 20 μm.

[0059] As long as the cutting width is within the above range, step [a] can be performed several times. From the viewpoint of forming a good cutting end face and efficiently performing cutting processing, step [a] is preferably performed 2 or more times, can be performed 3 or more times, and is usually 10 or less times, preferably 5 or less times.

[0060] When the step [a] is performed two or more times, the cutting width may be set to 150 μm or less in any of the times, and the cutting widths in each time may be the same or different. When the step [a] is performed two or more times, for example, a cutting process with a large cutting width may be performed first, and then a cutting process with a small cutting width may be performed.

[0061] As described above, in the manufacturing method of the polarizer 10, the cutting width of each cutting process performed to form the recessed portion 11 is made small. Thus, it is possible to suppress the occurrence of long cracks around the recessed portion 11 due to the condensation thermal shock test of the polarizer 10. The so-called cracks are cracks that penetrate or do not penetrate the outer surface or thickness direction of the polarizer 10, and the cracks are completely separated.

[0062] The cracks are presumed to be generated starting from the silver streaks (fine cracks on the surface and inside of the polarizer 10) described later existing on the surface and inside of the polarizer 10 due to the contraction of the polarizer caused by the condensation heat shock test. In particular, it is presumed that stress is easily concentrated in the concave portion 11 of the polarizer 10 due to the contraction and expansion of the polarizer caused by the condensation heat shock test, and thus long cracks are easily generated around the concave portion 11 starting from the silver streaks.

[0063] Based on these points, it is believed that in order to reduce the generation of long cracks caused by the condensation heat shock test, it is necessary to suppress the silver streaks generated around the concave portion 11 of the polarizer 10. Silver streaks are presumed to be generated due to the load applied to the raw material polarizer 30 during punching, cutting or cutting. On the other hand, it is believed that by making the cutting width of each cutting process small as described above, the cutting resistance generated by the cutting process of the raw material polarizer 30 can be relatively small. In addition, it is believed that by making the cutting width of each cutting process small, the amount of load accumulated in the polarizer accompanying the cutting process can also be relatively reduced. Based on these points, it is presumed that by performing cutting as in the above-mentioned step [a], the silver streaks generated around the concave portion 11 of the polarizer 10 can be suppressed. As a result, it is believed that in the polarizer 10 in which the concave portion 11 is formed by making the cutting width of each cutting process small, the generation of long cracks caused by the condensation heat shock test can be suppressed.

[0064] In particular, it is envisioned that the polarizer 10 with the recess 11 is used in the display device of the portable terminal such as a smart phone and a tablet computer, and an earpiece, a speaker, a camera lens, various sensors, etc. are configured in the area of ​​the recess 11. In portable terminals such as smart phones and tablet computers, narrow frame is promoted from the perspective of expansion of the display area and design. For this reason, even if the crack of the length that is not a problem in the display device with a relatively wide frame is hidden by the frame, it will also have an adverse effect on the display area in the display device that has achieved narrow frame, so it sometimes becomes a problem. As described above, the polarizer 10 that suppresses the generation of long cracks caused by the condensation heat shock test can be suitably used for portable terminals such as smart phones and tablet computers that have promoted narrow frame.

[0065] like Figure 3 The raw material polarizing plate 30 in which the recessed portion 11 is formed by cutting as in (a) to (d) is cut, for example, by Figure 4 By further performing cutting as shown in (a) to (c) of FIG. 1 , the polarizing plate 10 can be manufactured. Figure 4 As shown in (a), Figure 3 The end of the raw polarizer 30 which has not been cut in the steps (a) to (d) is brought into contact with the end surface of the raw polarizer 30 by the cutting portion 52 of the end mill 50 rotating about the rotation axis 51, while the end mill 50 is moved relative to the peripheral portion of the raw polarizer 30. Figure 4 The cutting process is performed while relatively moving in the direction indicated by the block arrow in (a). Figure 4 As shown in (b) of FIG. 1 , a step [b] of forming the peripheral portion of the polarizing plate 10 other than the recessed portion 11 is performed. Step [b] Figure 4As shown in (b) of FIG. 1 , the process of cutting and processing the corners of the raw material polarizing plate 30 to be chamfered to form a rounded shape (having an R shape) can be included. Figure 1 The polarizing plate 10 ( Figure 4 (c)).

[0066] The cutting width per time in the above-mentioned step [b] is not particularly limited. The cutting width per time in the step [b] may be, for example, 150 μm or less, or may exceed 150 μm. The cutting width per time in the step [b] may be the same as that of the step [a] performed before or after the step [b].

[0067] Step [b] can be performed once or twice or more. From the perspective of forming a good cutting end face and efficiently performing cutting processing, step [b] is usually preferably performed twice or more, and can also be performed three or more times, usually 10 times or less, preferably 5 times or less. The number of times step [b] is performed can be the same as step [a] performed before or after step [b].

[0068] 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. Figure 5 (a) and (b) are diagrams for explaining the relationship between the rotation direction and the relative movement direction of the end mill. Figure 5 As shown in (a), the rotation direction of the end mill 50 in the contact portion between the end face of the raw polarizer 30 and the cutting portion 52 of the end mill 50 (the direction indicated by the linear arrow in the figure) can be the same as the relative movement direction of the end mill 50 with respect to the peripheral portion of the raw polarizer 30 (the direction indicated by the block arrow in the figure), so-called upward direction, or it can be the opposite downward direction. The so-called downward direction is as shown in FIG. Figure 5 As shown in (b), the rotation direction of the end mill 50 (the direction indicated by the linear arrow in the figure) in the contact portion between the end face of the raw polarizer 30 and the cutting portion 52 of the end mill 50 is opposite to the relative movement direction of the end mill 50 with respect to the peripheral portion of the raw polarizer 30 (the direction indicated by the block arrow in the figure). In order to shorten the length of the crack generated around the recessed portion 11, the above step [a] preferably performs the cutting process by setting the rotation direction of the end mill 50 to the upward direction.

[0069] In the cutting process of the above-mentioned step [A], the rotation speed of the end mill 50 is not particularly limited, and is usually above 500 rpm, but may be above 1000 rpm, above 5000 rpm, above 10000 rpm, or above 20000 rpm. The rotation speed of the end mill 50 is usually below 60000 rpm, but may be below 55000 rpm, or below 50000 rpm. When step [A] includes step [a] and step [b], the rotation speed of the end mill 50 may be the same or different in step [a] and step [b], and may be partially different in step [a] and step [b].

[0070] In the cutting process of the above-mentioned step [A], the relative moving speed (feeding speed) of the end mill 50 relative to the raw material polarizer 30 is not particularly limited, and is usually 100 mm / min or more, and may be 500 mm / min or more, and may be 1000 mm / min or more. In addition, it is usually 3000 mm / min or less, and may be 2500 mm / min or less, and may be 2000 mm / min or less. In the case where the step [A] includes the step [a] and the step [b], the relative moving speed (feeding speed) of the end mill 50 relative to the raw material polarizer 30 may be the same in the step [a] and the step [b], or may be different from each other, or may be partially different in the step [a] and the step [b].

[0071] The above-mentioned step [A] can be performed with one raw polarizer 30, or with two or more raw polarizers 30 stacked. When the raw polarizers 30 are stacked, the number of stacked sheets depends on the thickness of the raw polarizers 30, but for example, it can be set to more than 10 sheets, more than 20 sheets, more than 30 sheets, or more than 40 sheets, and is usually less than 100 sheets, less than 80 sheets, or less than 60 sheets.

[0072] Figure 3 The cutting steps shown in (a) to (d) and Figure 4 The end mills 50 used in the cutting steps (a) to (c) may be the same or different from each other. When different end mills 50 are used, the types of end mills (cutting edge shape, cutting edge orientation or angle, cutting edge spiral orientation or angle, etc.) may be different from each other. Figure 3 The cutting steps shown in (a) to (d) and Figure 4 In the cutting steps shown in (a) to (c), the cutting conditions in each cutting step (rotation speed, rotation speed, relative movement speed, rotation direction, relative movement direction, etc. of the end mill) may be the same as or different from each other.

[0073] exist Figure 3 (a) to (d) and Figure 4 In the method for manufacturing the polarizing plate 10 shown in (a) to (c), Figure 3 as well as Figure 4 In the process of cutting the raw polarizer 30, the end mill 50 is relatively moved counterclockwise along the peripheral edge of the raw polarizer 30 ( Figure 3 (a) to (d)), and a step of relatively moving the end mill 50 clockwise along the peripheral edge of the raw material polarizer 30 to perform cutting processing ( Figure 4 (a) to (c)), thereby manufacturing the polarizer 10, but it is not limited to this. For example, the end mill 50 can also be relatively moved counterclockwise or clockwise along the peripheral edge of the raw material polarizer 30 for one circle to perform the cutting process of the raw material polarizer 30. The starting position and the ending position of the cutting process of the raw material polarizer 30 are also not limited to Figure 3 The positions shown in (a) and (d) of Figure 4 Any position can be selected from the positions shown in (a) and (c).

[0074] In addition, the peripheral portion of the raw material polarizing plate 30 is not limited to being divided into two ranges. Figure 3 The steps (a) to (d) and Figure 4 The method of cutting the raw polarizer 30 by the steps (a) to (c) can also be used to divide the peripheral portion of the raw polarizer 30 into arbitrary ranges, and cut each range in an arbitrary order. In this case, the type of the end mill 50 used in each process and the cutting conditions in each process can be the same or different. In addition, the cutting process in each range can be performed twice or more.

[0075] (Polarizing Plate)

[0076] Figure 6 1 is a schematic cross-sectional view schematically showing an example of a polarizing plate. Figure 1 As shown in FIG. 1 , a concave portion 11 is provided at the peripheral portion when viewed from above, for example Figure 6 As shown in the figure, protective layers 2 and 3 are provided on both sides of the polarizing element layer 1. The polarizing plate 10 may also have only one of the protective layers 2 and 3. The polarizing element layer 1 is a polyvinyl alcohol-based resin layer that absorbs and orients a dichroic pigment. The protective layers 2 and 3 may be layers that are directly in contact with the polarizing element layer 1, or layers that are provided via an adhesive layer or a bonding agent layer. The polarizing plate 10 has no silver streaks at a position of 30 μm and a position of 50 μm in the surface direction from an edge that exists in an arbitrary range of 5 mm in length along the contour of the recess 11.

[0077] The edge within the above-mentioned arbitrary range is not particularly limited as long as it is along the range of the contour of the recessed portion 11 of the polarizer 10. The contour of the recessed portion 11 is preferably a portion that is more than 5 mm long and becomes a straight line. In the case where the recessed portion 11 of the polarizer 10 includes a straight line portion and a curved line portion, the edge within the above-mentioned arbitrary range is preferably an edge that exists in the range of 5 mm in length from the side adjacent to (connected to) the curved line portion in the straight line portion.

[0078] Specifically, Figure 1 As shown, when the contour of the recess 11 of the polarizer 10 has two sides 11a and 11c that are arranged opposite to each other and each having a straight line portion, and one side 11b that connects the two sides 11a and 11c and has a straight line portion, it is considered that the stress caused by the wet heat shock test is likely to be concentrated at the position 11ab where one of the two sides 11a and the other side 11b are connected, the position 11bc where the other of the two sides 11c and the other side 11b are connected, and their vicinities. For this reason, the edge within the above-mentioned arbitrary range is preferably set to an edge that exists within a length range of 5 mm from the side where one of the two sides 11a and 11c is connected to the other side 11b in the straight line portion of the one side 11b. The so-called straight line portion of the one side 11b is as follows: Figure 1 When the recess 11 has a rounded corner portion as in the polarizing plate 10 shown, the rounded corner portion is a straight portion excluding a curved portion constituting the rounded corner portion including a portion where one of the two sides 11a and 11c is in contact with the one side 11b.

[0079] The contour of the recess 11 is the entire periphery of the portion of the periphery of the polarizer 10 that forms the contour of the recess 11. Regarding the boundary between the portion that forms the contour of the recess 11 and the portion that forms the contour of the periphery other than the recess 11, when the boundary is a corner, it is the vertex of the corner, and when the boundary has a rounded corner (when the corner has an R shape), it is set to the position that divides the contour length of the rounded corner into two equal parts. The edge of the recess 11 of the polarizer 10 is also called the edge of the outermost portion in the surface direction among the end faces (surfaces along the thickness direction) in the recess 11 of the polarizer 10. Regarding the distance from the edge of the recess 11 in the direction of the surface, when the edge existing in any of the above-mentioned ranges is linear, it is the distance in the direction orthogonal to the linear edge when viewed from above. When the edge existing in any of the above-mentioned ranges is curved, at each position of the curved edge, the distance in the direction orthogonal to the tangent passing through the position is set as the distance from the edge of the recess 11 in the direction of the surface.

[0080] As described above, the silver streaks are fine cracks on the surface or inside of the polarizer 10. As described later, the polarizer 10 may have layers other than the polarizer layer 1 and the protective layers 2 and 3. The silver streaks of the polarizer 10 are silver streaks existing in the polarizer layer 1 and the protective layers 2 and 3. The silver streaks may be formed in the cross section of the polarizer 10, for example, Figure 7 is observed as shown in (a). Figure 7 (a) and (b) are diagrams showing images obtained by observing a cross section of the polarizing plate 10 using a scanning laser microscope.

[0081] Figure 7 (a) shows an example of an image in which silver streaks exist in the cross section of the polarizing plate 10. The silver streaks exist in Figure 7 In contrast, when there are no silver streaks in the cross section of the polarizing plate 10, as shown in FIG. Figure 7 As shown in (b), it cannot be confirmed Figure 7 The portion shown by the dotted line in (a).

[0082] The polarizing plate 10 has no silver streaks at a position of 30 μm and 50 μm in the plane direction from an edge existing in the arbitrary range within a length of 5 mm along the contour of the recess 11 as described above. In addition, the polarizing plate 10 may or may not have silver streaks at a position of 10 μm in the plane direction from an edge existing in the arbitrary range.

[0083] It is speculated that the long cracks caused by the condensation heat shock test are easy to be generated from the silver streaks existing in the polarizer 10 as the starting point, in the direction of the edge of the recess 11 and in the opposite direction to the edge. Accordingly, if there are silver streaks at a position away from the surface direction from the edge of the recess 11 of the polarizer 10, it is considered that the length of the cracks caused by the condensation heat shock test is relatively long. Therefore, as described above, it is believed that the polarizer 10 has no silver streaks at a position of 30 μm and 50 μm in the surface direction from the edge of the recess 11, which can suppress the situation of long cracks in the polarizer 10 caused by the condensation heat shock test. On the other hand, even if the polarizer 10 has silver streaks at a position of 10 μm in the surface direction from the edge of the recess 11, it is also considered that the cracks caused by the condensation heat shock test are short. For this reason, it is believed that it is difficult to have an adverse effect on the display area of ​​portable terminals such as smart phones and tablets, but it is preferred that the polarizer 10 has no silver streaks at a position of 10 μm in the surface direction from the edge of the recess 11.

[0084] Figure 8(a) and (b) are schematic top views schematically showing another example of a polarizing plate. The top view shape of the polarizing plate 10 is not particularly limited. For example, it may be a square or a rounded square having a concave portion 11 on at least one side. The rounded square, for example, Figure 1 , Figure 8 As shown in (a) and (b), one or more of the four corners in the square (for example, all four corners) are rounded with a given radius of curvature. The so-called square is a rectangle or a square. The shape of the polarizing plate 10 when viewed from above is not limited to a square, and may also be a polygon other than a square, a circle, or an ellipse.

[0085] The concave portion 11 of the polarizing plate 10 may have one or more concave portions 11 at the periphery of the polarizing plate 10 when viewed from above. Figure 1 , Figure 8 In the case of a rounded square as shown in (a) and (b), at least one side thereof may have one or more recesses 11, for example, one of the short sides may have a recess 11. There may be two or more recesses 11 on one side, or there may be one or more recesses 11 on each of two or more sides.

[0086] The size of the polarizing plate 10 is not particularly limited. However, when the polarizing plate 10 is rectangular, for example, the length of the short side can be set to 30 mm to 90 mm, and the length of the long side can be set to 30 mm to 170 mm.

[0087] The shape of the concave portion 11 of the polarizing plate 10 is not particularly limited. Figure 1 It is a quadrilateral as shown, or it can be Figure 8 It is a U-shape as shown in (a), and can also be Figure 8 In the case where the concave portion 11 is a quadrilateral, it is not limited to a rectangle and may be a square. The corners of the concave portion may be chamfered and rounded. Figure 8 As shown in (b), the top of the V-shaped recess 11 (the deepest part in the surface direction) is chamfered. Although not shown in the figure, the shape of the recess 11 of the polarizing plate 10 can also be a trapezoid, an arc shape, a quadrilateral, or a polygon other than a triangle. The shape of the recess 11 can be as follows: Figure 1 , Figure 8 The contour of the recess 11 may be formed by one of a straight line portion and a curved line portion, or may include both a straight line portion and a curved line portion.

[0088] In such Figure 8When the recess 11 is U-shaped or V-shaped as shown in (a) and (b), the edge existing in any range of 5 mm in length along the contour of the recess 11 is preferably a part of the straight portion of the recess 11, and more preferably an edge existing in a range of 5 mm in length from the side of the straight portion adjacent to (connected to) the curved portion. Specifically, Figure 8 In the polarizer 10 shown in (a) and (b), the edge can be set to exist in a straight line portion adjacent to the curved portion including the top (the deepest portion in the surface direction) of the recess 11, within a length of 5 mm from the side adjacent to the curved portion (for example, the portion surrounded by a dotted line in the figure).

[0089] The corners provided inside the recess 11 of the polarizing plate 10 are preferably chamfered to have a rounded shape (having an R shape). The corners provided inside the recess 11 refer to the corners provided inside the recess 11, which are outside the boundary between the contour of the recess 11 and the peripheral portion outside the recess 11. Specifically, for example, Figure 1 In the polarizing plate 10 shown, it is preferred that the positions 11ab and 11bc are rounded. By rounding the corners inside the recess 11, it becomes easy to suppress the generation of cracks caused by the condensation heat shock test at the portion. The corners of the boundary portion between the contour of the recess 11 and the peripheral portion outside the recess 11 can also be chamfered to have a rounded shape (having an R shape).

[0090] The size of the concave portion 11 of the polarizing plate 10 is not particularly limited, but the maximum length ( Figure 1 , Figure 8 The distance indicated by w in (a) and (b) can be set to, for example, 3 mm or more and 160 mm or less. The maximum depth of the recess 11 (in the direction perpendicular to the side forming the recess 11) Figure 1 , Figure 8 The distance (indicated by d) in (a) and (b) can be set, for example, to a range of 0.5 mm to 160 mm.

[0091] As described above, the polarizer 10 has protective layers 2 and 3 on one or both sides of the polarizer layer 1. When the polarizer 10 has protective layers 2 and 3 on both sides of the polarizer layer 1, the polarizer layer 1 ( Figure 6 ), the polarizing element layer 1 may be omitted and the layers may be directly overlapped, or the two protective layers 2 and 3 may be welded.

[0092] The polarizer 10 may further include an adhesive layer on the side of the protective layers 2 and 3 opposite to the polarizer layer 1, and may further include a release film on the side of the adhesive layer opposite to the protective layers 2 and 3. The adhesive layer and the release film may be provided on one side or both sides of the polarizer 10. The adhesive layer is used to attach the polarizer 10 to an image display element of a display device such as a liquid crystal display device or an organic EL display device. The release film is used to cover and protect the adhesive layer and can be peeled off relative to the adhesive layer.

[0093] The polarizer 10 may further include an optical functional layer on the side of the protective layers 2 and 3 opposite to the polarizing element layer 1. The optical functional layer may be provided on one side or both sides of the polarizer 10. In the case where the polarizer 10 has the above-mentioned adhesive layer, the optical functional layer may be provided on the side of the polarizer 10 opposite to the side provided with the adhesive layer, or may be provided between the polarizer 10 and the adhesive layer.

[0094] The polarizer 10 may include a protective film on the side of the protective layers 2 and 3 opposite to the polarizer layer 1. The protective film is provided to suppress scratches, stains, etc. on the surface of the polarizer 10 during the manufacture of a product using the polarizer 10, the manufacture or transportation of the polarizer 10. When the polarizer 10 has an optical functional layer, the protective film is provided on the side of the optical functional layer opposite to the polarizer layer 1. The protective film can be peeled off relative to the surface of the polarizer 10.

[0095] The polarizer 10 can be stacked on an image display element of a display device and used. As a display device, a liquid crystal display device or an organic EL display device can be cited. In the case where the display device is a liquid crystal display device, the polarizer 10 can be stacked on one surface of a liquid crystal panel having a liquid crystal cell, or the polarizer 10 can be stacked on both sides of the liquid crystal panel. In the case of applying the polarizer 10 to a display device, the polarizer 10 is preferably stacked on the image display element via an adhesive layer or an adhesive layer.

[0096] (Raw polarizing plate)

[0097] The raw material polarizer 30 is used to obtain the polarizer 10. As described above, the raw material polarizer 30 is preferably cut into a given shape and size by punching, cutting, etc. By subjecting such a raw material polarizer 30 to a cutting process based on the above-mentioned step [A], for example, the polarizer 10 can be obtained.

[0098] The raw material polarizer 30 has a protective layer on one side or both sides of the polarizer layer. The polarizer layer is a polyvinyl alcohol-based resin layer that absorbs dichroic pigments and is oriented. The protective layer can be a layer that is directly connected to the polarizer layer, or a layer that is provided across an adhesive layer or an adhesive layer. In order to obtain the polarizer 10 by cutting the raw material polarizer 30, the raw material polarizer 30 is usually preferably provided with the same layer structure as the polarizer 10. Therefore, the raw material polarizer 30 can be provided with the above-mentioned adhesive layer, optical functional layer, protective film, etc. that the polarizer 10 can have on one side or both sides thereof. In the case where the raw material polarizer 30 is provided with an adhesive layer, a release film is preferably provided on the side of the adhesive layer opposite to the polarizer layer.

[0099] The shape of the raw material polarizing plate 30 when viewed from above is not particularly limited, but is preferably a shape that is substantially similar to the shape of the polarizing plate 10 manufactured using the raw material polarizing plate 30. Since the polarizing plate 10 has the concave portion 11, the raw material polarizing plate 30 is also preferably, for example, Figure 3 As shown in (a) of FIG. 3 , the notch 31 has a concave shape. The corners of the raw polarizing plate 30 and the corners of the notch 31 may not be chamfered.

[0100] For example, a long strip-shaped laminated body in which a long strip-shaped polarizing element layer and a long strip-shaped protective layer are bonded is obtained, and the laminated body is cut into a size that is easy to perform the cutting process in the above-mentioned step [A], thereby obtaining a raw polarizer 30. The cutting of the raw polarizer 30 can be performed by punching and cutting. A tool or laser can be used in the cutting process. In the case where the raw polarizer 30 has a concave notch 31, the notch 31 can be formed by punching and cutting the laminated body cut out of the above-mentioned laminated body into a given size, or the raw polarizer 30 having the notch 31 can be obtained by punching and cutting the above-mentioned laminated body.

[0101] The polarizing plate 10 and each layer used in the raw polarizing plate will be described in detail below.

[0102] (Polarizing element layer)

[0103] The polarizer layer 1 is preferably a film-like polyvinyl alcohol resin layer (PVA film) adsorbed and oriented with a dichroic dye produced by stretching, dyeing, crosslinking, etc. The polarizer layer 1 can be produced by a known method, for example, by the following procedure.

[0104] First, the PVA film is stretched in a uniaxial direction or a biaxial direction. The dichroic ratio of the polarizing element layer 1 after stretching in a uniaxial direction tends to be high. Immediately after stretching, the PVA film is dyed with iodine, a dichroic pigment (polyiodine) or an organic dye using a dyeing solution. The dyeing 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 blocking inhibitors can be removed from the surface of the PVA film.

[0105] In addition, as a result of swelling of the PVA film by washing with water, the generation of dyeing spots (uneven dyeing) can be suppressed. The dyed PVA film is treated with a solution of a crosslinking agent (e.g., an aqueous solution of boric acid) for crosslinking. After the treatment based on the crosslinking agent, the PVA film is washed with water and then dried. By the above, a polarizing element layer 1 can be obtained.

[0106] Polyvinyl alcohol (PVA) resins are obtained by saponifying polyvinyl acetate resins. As polyvinyl acetate resins, for example, single polymers of vinyl acetate, i.e., polyvinyl acetate, or copolymers of vinyl acetate and other monomers (e.g., ethylene-vinyl acetate copolymers) can be cited. As other monomers copolymerized with vinyl acetate, in addition to ethylene, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, or acrylamides with ammonium groups can also be cited. Polyvinyl alcohol resins can be modified with aldehydes. Modified polyvinyl alcohol resins can be, for example, partially formalized polyvinyl alcohol, polyvinyl acetal, or polyvinyl butyral. Polyvinyl alcohol resins can be polyene-based oriented films such as dehydrated products of polyvinyl alcohol or dehydrochlorinated products of polyvinyl chloride.

[0107] The PVA film used in the above may be dyed before stretching, or may be stretched in a dyeing solution. The length of the polarizing element layer 1 after stretching can be, for example, 3 to 7 times the length before stretching.

[0108] The thickness of the polarizer layer 1 can be set to be, for example, 1 μm or more, or 3 μm or more, and is usually 50 μm or less, or 15 μm or less. The smaller the thickness of the polarizer layer 1, the more the contraction or expansion of the polarizer layer 1 itself associated with temperature changes is suppressed, and the more the change in the size of the polarizer layer 1 itself is suppressed. As a result, the stress associated with contraction and expansion is difficult to act on the polarizer layer 1, and it is easy to suppress cracks in the polarizer layer 1 caused by the condensation thermal shock test.

[0109] (Protective layer)

[0110] The protective layers 2 and 3 can be formed using an optically transparent thermoplastic resin having light transmittance. As the resin constituting the protective layers 2 and 3, there can be cited chain polyolefin resins, cyclic olefin polymer resins (COP resins), cellulose ester resins, polyester resins, polycarbonate resins, (meth) acrylic resins, polystyrene resins, or mixtures thereof or copolymers thereof. "(Meth) acrylic acid" refers to at least one selected from the group consisting of acrylic acid and methacrylic acid.

[0111] Examples of the chain polyolefin resin include single polymers of chain olefins such as polyethylene resin and polypropylene resin. The chain polyolefin resin may be a copolymer containing two or more chain olefins.

[0112] As cyclic olefin polymer resins (cyclic polyolefin resins), for example, ring-opening (co)polymers of cyclic olefins or addition polymers of cyclic olefins can be cited. Cyclic olefin polymer resins can be, for example, copolymers (for example, random copolymers) of cyclic olefins and chain olefins. The chain olefins constituting the copolymers can be, for example, ethylene or propylene. Cyclic olefin polymer resins can also be graft polymers obtained by modifying the above-mentioned polymers with unsaturated carboxylic acids or their derivatives, or their hydrogenates. Cyclic olefin polymer resins can be, for example, norbornene resins using norbornene monomers such as norbornene or polycyclic norbornene monomers.

[0113] Examples of the cellulose ester resin include cellulose triacetate (triacetylcellulose (TAC)), cellulose diacetate, cellulose tripropionate, and cellulose dipropionate, and copolymers thereof may be used. The cellulose ester resin may be a cellulose ester resin in which a part of the hydroxyl groups is modified with other substituents.

[0114] The polyester resin includes polyester resins other than cellulose ester resins. Examples of such polyester resins include polycondensates of polycarboxylic acids or derivatives thereof and polyols. Examples of polycarboxylic acids or derivatives thereof include dicarboxylic acids or derivatives thereof, such as terephthalic acid, isophthalic acid, dimethyl terephthalate, or dimethyl naphthalene dicarboxylate. Examples of polyols include diols, such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, or cyclohexanedimethanol.

[0115] Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethylene terephthalate, and polycyclohexanedimethylene naphthalate.

[0116] The polycarbonate resin is a polymer obtained by bonding polymer units (monomers) via carbonate groups. The polycarbonate resin may be a modified polycarbonate having a modified polymer skeleton or a copolymerized polycarbonate.

[0117] Examples of the (meth)acrylic resin include poly(meth)acrylates (e.g., polymethyl methacrylate (PMMA)); methyl methacrylate-(meth)acrylic acid copolymers; methyl methacrylate-(meth)acrylic acid ester copolymers; methyl methacrylate-acrylate-(meth)acrylic acid copolymers; methyl (meth)acrylate-styrene copolymers (e.g., MS resin); and copolymers of methyl methacrylate and a compound having an alicyclic hydrocarbon group (e.g., methyl methacrylate-cyclohexyl methacrylate copolymers, methyl methacrylate-norbornyl (meth)acrylate copolymers, etc.).

[0118] 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 preferably 200° C. or lower, more preferably 150° C. or lower. When 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 can be fused to each other by the heat generated by the cutting process of the raw material polarizer 30.

[0119] The protective layers 2 and 3 may contain at least one additive selected from the group consisting of a lubricant, a plasticizer, a dispersant, a heat stabilizer, an ultraviolet absorber, an infrared absorber, an antistatic agent, and an antioxidant.

[0120] In the case where the polarizer 10 has 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 as or different from each other. By including cellulose ester resins such as triacetyl cellulose (TAC) in the protective layers 2 and 3, it is easy to suppress long cracks generated around the recess 11 due to the condensation thermal shock test. On the other hand, in the case where the protective layers 2 and 3 include cyclic olefin polymer resins (COP resins), the cracks generated around the recess 11 due to the condensation thermal shock test become longer, and the number of cracks also tends to increase. Regarding the above-mentioned method for manufacturing a polarizer, it is preferred because long cracks can be suppressed even when manufacturing a polarizer having protective layers 2 and 3 containing COP resins.

[0121] The thickness of the protective layers 2 and 3 is, for example, 5 μm or more, or 10 μm or more, and is usually 90 μm or less, or 60 μm or less. When the polarizer 10 has protective layers 2 and 3 on both sides of the polarizing element layer 1, the thickness of the two protective layers 2 and 3 may be the same as or different from each other.

[0122] The protective layers 2 and 3 may be films having optical functions. Examples of films having optical functions include phase difference films and brightness enhancement films. Phase difference films may be obtained, for example, by stretching a film containing the above-mentioned thermoplastic resin or forming a liquid crystal layer on the film.

[0123] 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 below.

[0124] The active energy ray-curable resin is a resin that is cured by being irradiated with active energy rays. Examples of active energy rays include ultraviolet rays, visible light, electron beams, and X-rays. For example, the active energy ray-curable resin may be an ultraviolet-curable resin.

[0125] The active energy ray-curable resin may contain one resin or a plurality 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 cationically polymerizable initiator or a radically polymerizable initiator for initiating the curing reaction of the curable compound.

[0126] Examples of cationically polymerizable curable compounds include epoxy compounds (compounds having at least one epoxy group in the molecule) or oxetane compounds (compounds having at least one oxetane ring in the molecule). Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having at least one (meth)acryloyloxy group in the molecule). Examples of radically polymerizable curable compounds include vinyl compounds having a radically polymerizable double bond.

[0127] The active energy ray-curable resin may contain a cationic polymerization accelerator, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, a defoamer, an antistatic agent, a leveling agent, or a solvent, as necessary.

[0128] (Adhesive layer)

[0129] The adhesive layer exhibits adhesiveness by attaching itself to the adherend, and can be formed by an adhesive called a pressure-sensitive adhesive. As the adhesive, a known adhesive can be used, for example, an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, or a urethane pressure-sensitive adhesive. The thickness of the adhesive layer can be set to, for example, 2 μm or more and 100 μm or less.

[0130] (Release film)

[0131] The release film is used for the purpose of covering and protecting the adhesive layer as described above. The release film is peeled off and removed when the polarizer 10 is attached to the image display element of the display device. As the release film, a resin film that has been subjected to a demolding treatment on the side in contact with the adhesive layer can be used. As the resin film, a film using the resin exemplified as the resin constituting the protective layer 2 and 3 can be cited. As the demolding treatment, a silicone coating can be cited. The thickness of the release film can be set to, for example, 10 μm or more and 100 μm or less.

[0132] (Optical functional layer)

[0133] The optical functional layer is not particularly limited as long as it is a layer having an optical function, and may also be a film. As the optical functional layer, for example, a phase difference film, a reflective polarizing film, a film with an anti-glare function, a film with a surface reflection prevention function, a reflective film, a semi-transmitted reflective film, a viewing angle compensation film, a window film, an antistatic layer, a hard coating, an optical compensation layer, a touch sensor layer, an antifouling layer, etc. can be cited. One or more of these can be used as the optical functional layer.

[0134] (Protective film)

[0135] The protective film is used for the purpose of protecting the surface of the polarizer 10 as described above. The protective film may be a film having an adhesive layer on a substrate film, or may be a self-adhesive film. As the resin used in the substrate film of the protective film, the resin used in the above-mentioned protective layers 2 and 3 can be cited, and as the adhesive layer, the above-mentioned adhesive can be cited. The self-adhesive film can be formed using, for example, a polypropylene resin and a polyethylene resin.

[0136] [Example]

[0137] The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0138] [Condensation thermal shock test]

[0139] Using the polarizing plates obtained in Examples and Comparative Examples, a condensation heat shock test was performed in which a process of performing the following steps 1 to 3 in order was defined as one cycle and this process was repeated continuously for 10 cycles.

[0140] Step 1:

[0141] The polarizing plate was kept in an environment of a temperature of -40°C and a relative humidity of 11%RH for 30 minutes.

[0142] Step 2:

[0143] The polarizing plate subjected to step 1 was kept in an environment of a temperature of 23° C. and a relative humidity of 9% RH for 5 minutes.

[0144] Step 3:

[0145] The polarizing plate subjected to step 2 was kept in an environment of a temperature of 85° C. and a relative humidity of 7% RH for 30 minutes.

[0146] The polarizing plates subjected to the above-mentioned condensation heat shock test were observed from above using an optical microscope to observe the periphery of the concave portion. Figure 1 Among the cracks generated near the positions 11ab and 11bc of the concave portion 11 shown in FIG. 1 , the crack with the longest length in the long side direction of the polarizer was taken as the length of the crack in the curved portion of the concave portion. Figure 1 In the straight portion of side 11b of the recess 11 shown, the length in the long side direction of the polarizer of the cracks generated at the edge within a length range of 5 mm from the side where side 11a and side 11b meet, and near the edge within a length range of 5 mm from the side where side 11b and side 11c meet, the crack with the longest length in the long side direction of the polarizer among the measured cracks is taken as the crack length in the straight portion of the recess.

[0147] [Example 1]

[0148] A protective layer formed of a cyclic olefin polymer resin and having a thickness of 52 μm is bonded to one surface of a polarizing element layer having a thickness of 8 μm, which is produced by stretching and dyeing a polyvinyl alcohol film, using a polyvinyl alcohol-based adhesive (aqueous adhesive). A protective layer formed of a cyclic olefin polymer resin and having a thickness of 21 μm is bonded to the other surface of the polarizing element layer via a UV-curable epoxy resin, and the UV-curable epoxy resin is cured by irradiating with ultraviolet rays, thereby laminating the polarizing element layer and the protective layer having a thickness of 21 μm. A protective film (thickness of 58 μm) having an adhesive layer formed on a substrate film is bonded to the protective layer having a thickness of 52 μm, and an adhesive layer having a thickness of 20 μm and a release film (thickness of 38 μm) are laminated in this order on the protective layer having a thickness of 21 μm, thereby obtaining a rectangular laminate. The thickness of the laminated structure from the protective layer with a thickness of 52 μm to the adhesive layer is 102 μm, which is obtained by laminating a protective film with a thickness of 58 μm on one side of the laminated structure and a release film with a thickness of 38 μm on the other side. In addition, in the obtained laminated body, the polarizing element layer and the protective layer with a thickness of 21 μm attached to the other side (a protective layer with a thickness of 21 μm formed by a cyclic olefin polymer resin) are bonded via a cured product of UV-curable epoxy resin, i.e., an adhesive layer (thickness 1 μm). The obtained laminated body is punched out using a pointed blade to produce 47 sheets. Figure 3 A raw material polarizing plate having the shape shown in (a).

[0149] 47 sheets of raw polarizers were stacked so that the release film side of the raw polarizers was on the lower side, and then placed on the stage of the cutting device and fixed to the stage by clamps. The end mill (DXL-4, manufactured by Nissin Tool Co., Ltd., diameter: 4 mm, right blade, cutting angle β: 65 [°]) installed on the cutting device was rotated so that the cutting part of the end mill came into contact with the end face (surface along the stacking direction) of the stacked raw polarizers, and three cutting processes were performed while the end mill was moved relative to the raw polarizers under top view. In each cutting process, the cutting width was set to 100 μm, the rotation speed of the end mill was set to 30,000 rpm, the feed speed (relative moving speed) of the end mill was set to 1000 mm / min, and the cutting process was performed in the upward direction.

[0150] Through the above cutting process, we can obtain Figure 1 A rectangular polarizing plate with a quadrilateral concave portion as shown. The short side of the polarizing plate is 70 mm long and the long side is 140 mm long. Figure 1 The distance of the portion indicated by w in the figure) is 30 mm, and the length in the long side direction ( Figure 1 The distance of the portion indicated by d in the figure 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 concave portion was measured. The results are shown in Table 1.

[0151] [Comparative Example 1]

[0152] The polarizing plate was obtained in the same manner as in Example 1 except that the cutting process was performed twice so that the cutting width of each time was as shown in Table 1. The obtained polarizing plate was subjected to a coagulation heat shock test to measure the crack length in the curved portion of the concave portion. The results are shown in Table 1.

[0153] [Example 2]

[0154] A cutting process was performed once so that the cutting width was as shown in Table 2. Other than this, a polarizing plate was obtained in the same manner as in Example 1. A polarizing plate was cut out from the linear portion of the side 11b of the concave portion of the polarizing plate obtained above so that a range of 5 mm in length from the side of the side 11b that was in contact with the side 11a became one side as a sample for measurement. The end face (surface along the thickness direction) of the above-mentioned side of the cut-out sample for measurement was scraped using a microtome, and the cross-sections at the positions of 10 μm, 30 μm, and 50 μm in the surface direction from the edge of the above-mentioned end face were observed using a scanning laser microscope (observation magnification: 100 times) to confirm the presence or absence of silver streaks. The results are shown in Table 2.

[0155] The obtained polarizing plate was subjected to a coagulation heat shock test, and the crack length in the curved portion of the concave part and the crack length in the linear portion were measured.

[0156] [Comparative Example 2]

[0157] The raw polarizing plate obtained in Example 1 was checked for the presence of silver streaks in the same procedure as in Example 2. In addition, a coagulation heat shock test was performed using the raw polarizing plate obtained in Example 1 to measure the crack length in the curved portion of the concave portion. The results are shown in Tables 1 and 2.

[0158] [Comparative Example 3]

[0159] The polarizing plate was obtained in the same manner as in Example 2 except that the cutting width was set as shown in Table 2. The polarizing plate obtained was checked for the presence or absence of silver streaks in the same order as in Example 2. In addition, the obtained polarizing plate was subjected to a condensation heat shock test to measure the crack length in the curved portion of the concave part and the crack length in the straight portion. The results are shown in Table 2.

[0160]

Table 1

[0161] Table 1

[0162] Example 1 Comparative Example 1 Comparative Example 2 Processing methods Cutting Cutting Blanking Cutting width First time [μm] 100 200 - 2nd time [μm] 100 100 - 3rd time [μm] 100 - - Condensation thermal shock test Crack length of the curved part [μm] 1100 1620 1960

[0163]

Table 2

[0164] Table 2

[0165] Example 2 Comparative Example 2 Comparative Example 3 Processing methods Cutting Blanking Cutting Cutting width [μm] 100 - 300 Presence of silver streaks 10μm from the edge have have have 30μm from the edge none have have 50μm from the edge none have none Condensation thermal shock test Crack length of the curved part [μm] 730 1960 900 Crack length of straight line part [μm] 370 - 750 .

Claims

1. A polarizing plate having a concave portion at the peripheral portion when viewed from above, wherein: The polarizing plate has protective layers of cyclic olefin polymer resin on both sides of the polarizing element layer. From the edge existing in any range of 5 mm in length along the contour of the recessed portion, no silver streaks exist at a position of 30 μm or 50 μm in the plane direction. Furthermore, silver streaks exist at a position of 10 μm in the plane direction from the edge existing in the arbitrary range.

2. The polarizing plate according to claim 1, wherein The profile of the concave portion has a curved portion and a straight portion, The edge existing in the arbitrary range is an edge existing in a range of 5 mm in length from the side adjacent to the curved portion in the linear portion.

3. The polarizing plate according to claim 1 or 2, wherein: The contour of the recess includes: two sides arranged to face each other and each having a straight line portion; and one side connecting the two sides and having a straight line portion. The edge existing in the arbitrary range is an edge existing in a range of 5 mm in length from the side where the one side contacts one of the two sides in the linear portion of the one side.

4. The polarizing plate according to claim 1 or 2, wherein: The polarizing element layer is a polyvinyl alcohol-based resin layer on which a dichroic dye is adsorbed and oriented.

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