KR20210033918A - Method for manufacturing polarizing plate and polarizing plate - Google Patents

Abstract

A manufacturing method of a polarizing plate which can suppress that a long crack occurs in the periphery of a recessed portion by a dew condensation heat shock test, and a polarizing plate are provided. The manufacturing method of the polarizing plate which has a recessed part in the peripheral part in a planar view comprises: a process of preparing a raw material polarizing plate having a protective layer on one side or both sides of the polarizer layer; a process of carrying out a cutting process so that a recessed part may be formed while moving an end mill relatively with respect to the peripheral part of a raw material polarizing plate; and a process [a] performing cutting processing to form the recessed part while moving the end mill relatively with respect to the peripheral part of a raw material polarizing plate. The cutting operation in the process [a] is a cutting operation performed so that the cutting width is 150 μm or less.

Description

Polarizing plate manufacturing method and polarizing plate {METHOD FOR MANUFACTURING POLARIZING PLATE AND POLARIZING PLATE}

The present invention relates to a method of 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 portable terminals such as smartphones and tablets, and it is known that a polarizing plate is also inserted in such portable terminals.

In a portable terminal such as a smartphone or a tablet, there is a case where a concave portion is formed at the periphery of the display (display portion). In a display having such a concave portion, a polarizing plate having a concave portion is used according to the shape of the display (for example, Patent Documents 1 and 2). As a method of obtaining a polarizing plate having a concave portion, a method of punching with a cutting blade to form a concave portion in a raw material polarizing plate, a method of forming a concave portion by cutting the end surface of the raw material polarizing plate, etc. are known (for example, Patent Document 2, etc.).

Patent Document 1: Japanese Patent Application Laid-Open No. 2018-25630 Patent Document 2: Japanese Patent Laid-Open No. 2018-12182

The cutting process on the end surface of the raw material polarizing plate is usually performed two or more times. In this case, first roughing is performed with a relatively large cutting width, and after that, finish cutting is performed with a relatively small cutting width.

When the above-described cutting process was performed to produce a polarizing plate having a concave portion, it was found that long cracks may occur around the concave portion by a condensation heat shock test of the polarizing plate. In portable terminals such as smartphones and tablets, there are cases in which the width of the frame is narrowed from the viewpoint of enlargement of the display area and design. In a portable terminal in which the width of such a frame is to be narrowed, it is difficult to conceal long cracks by the frame, and thus problems such as display defects may occur.

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

The present invention provides the following polarizing plate manufacturing method and polarizing plate.

[1] As a method of manufacturing a polarizing plate having a concave portion at the periphery in plan view,

A step of preparing a raw material polarizing plate having a protective layer on one or both sides of the polarizer layer, and

A step [a] of performing cutting to form the concave while moving the end mill relative to the circumferential edge of the raw material polarizing plate,

The cutting process in the step [a] is a cutting process in which 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-shaped notch in a region in which the concave portion is formed.

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

[4] [1] to [1]-further comprising a step [b] of performing cutting to form a peripheral edge portion of the polarizing plate other than the concave portion while moving the end mill relative to the peripheral edge portion of the raw material polarizing plate. The manufacturing method of the polarizing plate in any one of [3].

[5] The method for manufacturing a polarizing plate according to [4], in which the step [a] and the step [b] are successively performed.

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

[7] As a polarizing plate having a concave portion at the peripheral edge in plan view,

The polarizing plate has a protective layer on one or both sides of the polarizer layer,

A polarizing plate in which craze does not exist either at a position of 30 μm and a position of 50 μm in the plane direction from the edge existing in an arbitrary range of 5 mm in length along the contour of the concave portion.

[8] Further, the polarizing plate according to [7], wherein craze is present or craze is not present at a position of 10 μm in the plane direction from the edge existing in the arbitrary range.

[9] The contour of the concave portion has a curved portion and a straight portion,

The polarizing plate according to [7] or [8], wherein the edge existing in the arbitrary range is an edge existing in the range of a length of 5 mm from the side adjacent to the curved portion in the linear portion.

(10) The contour of the concave portion includes two sides formed to face each other and each having a straight portion, and one side connecting the two sides and having a straight portion, and is within the arbitrary range. The existing edge is in any one of [7] to [9], which is an edge in a range of 5 mm from the side where one of the one side and one of the two sides in the straight portion of the one side. Described polarizing plate.

[11] The polarizing plate according to any one of [7] to [10], wherein the polarizer 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 occurrence of long cracks around the concave portion by a condensation heat shock test.

1 is a schematic plan view schematically showing an example of a polarizing plate of the present invention.
2 is a schematic front view schematically showing an example of an end mill used in the method for manufacturing a polarizing plate of the present invention.
3A to 3D are schematic top views schematically showing an example of a method for manufacturing a polarizing plate of the present invention.
4A to 4C are schematic top views schematically showing an example of a method for manufacturing a polarizing plate of the present invention.
5A and 5B are explanatory diagrams illustrating the relationship between the rotation direction and the movement direction of the end mill.
6 is a schematic cross-sectional view schematically showing an example of the polarizing plate of the present invention.
7A and 7B are diagrams showing images obtained by observing a cross section of a polarizing plate with a scanning laser microscope.
8A and 8B 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.

(Method of manufacturing a polarizing plate)

1 is a schematic plan view schematically showing an example of a polarizing plate of the present embodiment. The manufacturing method of the polarizing plate of this embodiment is a manufacturing method of the polarizing plate 10 which has the concave part 11 at the peripheral edge part in plan view, as shown in FIG. 1, for example. The manufacturing method of the polarizing plate 10 includes a step of preparing a raw material polarizing plate 30 having a protective layer on one or both sides of the polarizer layer, and moving the end mill 50 relative to the peripheral edge of the raw material polarizing plate 30. While making it, it includes a step [a] of performing a cutting process so as to form the concave portion 11. The cutting process in step [a] is a cutting process performed so that the cutting width becomes 150 μm or less. The cutting process performed by the manufacturing method of the polarizing plate 10 also includes a polishing process.

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 an end surface (a surface along the thickness direction) of the raw material polarizing plate 30. The end mill 50 is, as shown in FIG. 2, provided with a cutting portion 52 having a cutting edge 52a on its outer circumferential surface on one tip side of a tool body having a rotation shaft 51. As shown in FIG. In the end mill 50 shown in FIG. 2, although the case where the cutting edge 52a is a right edge is shown, it is not limited to this. For example, the cutting edge 52a may be a left edge, and the twist direction of the edge may be a right twist or a left twist.

The cutting angle β of the end mill 50 is, 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 the following formula when the helix angle of the end mill 50 is α[°]:

β=90°-α

It is represented by The spiral angle α is an angle formed by the direction d1 in which the cutting edge 52a extends from the outer circumferential surface of the end mill 50 and the rotation shaft 51 as shown in FIG. 2. In other words, the cutting angle β is an angle formed by the direction d1 in which the cutting edge 52a extends and the direction d2 perpendicular to the rotation shaft 51 as shown in FIG. 2.

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

In the method of manufacturing the polarizing plate 10 by cutting the raw material polarizing plate 30 using the end mill 50, for example, the raw material polarizing plate 30 disposed on the mounting table of the cutting device is fixed with a clamp or the like. By fixing by and moving the end mill 50 or the mounting table, cutting is performed while moving the end mill 50 relative to the circumferential edge portion of the raw material polarizing plate 30. The relative movement of the end mill 50 with respect to the circumferential edge of the raw material polarizing plate 30 is performed, for example, as shown in Figs. 3 (a) to (d) and Figs. 4 (a) to (c). I can. 3A to 3D and 4A to 4C are schematic top views schematically showing an example of a method for manufacturing a polarizing plate.

In the manufacturing method of the polarizing plate 10, first, as shown in Fig. 3A, a step of preparing the raw material polarizing plate 30 cut into a predetermined shape and size is performed. In Fig. 3A, a rectangular raw material polarizing plate 30 in which a concave cutout 31 is formed on one side is shown. This raw material polarizing plate 30 can be obtained by forming the cutout 31 by further performing punching or cutting on one side of the cutout piece cut into a rectangular shape by, for example, punching or cutting. The raw material polarizing plate 30 may be cut into a shape having the notch 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 portion of the raw material polarizing plate 30 (hereinafter, sometimes referred to as step [A]) is performed. The cutting processing in step [A] can be performed by bringing the cutting portion 52 of the end mill 50 rotating around the rotation shaft 51 into contact with the end surface of the raw material polarizing plate 30. The end surface of the raw material polarizing plate 30 is a surface along the thickness direction (a direction orthogonal to the surface direction) of the raw material polarizing plate 30. By performing the step [A], the concave portion 11 of the polarizing plate 10 is formed in the region of the cutout 31 of the raw material polarizing plate 30 (step [a]), and other than the cutout 31 In the region, a peripheral edge portion other than the concave portion 11 of the polarizing plate 10 can be formed (step [b]).

More specifically, by performing cutting with respect to the peripheral edge of the raw material polarizing plate 30, for example, by moving the end mill 50 relative to the direction indicated by the block arrow in FIGS. 3A to 3C. , As shown in FIGS. 3B and 3C, a step [b] of forming a peripheral edge portion of the polarizing plate 10 other than the concave portion 11 is performed. Step [b], as shown in Fig. 3 (b) and (c), includes a step of forming a rounded corner shape (rounded shape) by performing a cutting process to chamfer the corners of the raw material polarizing plate 30. I can. By further performing cutting processing in succession to this step [b], the step [a] of forming the concave portion 11 as shown in Fig. 3D can be performed. The step [a] may include a step of forming the concave portion 11 and forming a rounded corner shape (rounded shape) by performing a cutting process so as to chamfer the corner of the concave portion 11.

Step [a] is a step of cutting a region in which the concave portion 11 is formed in the raw material polarizing plate 30, and the concave portion 11 is formed by performing this step [a] one or more times. . The cutting process in step [a] is performed so that the cutting width per one time is 150 μm or less. The cutting width is, with respect to the raw material polarizing plate 30, each position (each point on the circumferential edge) of the circumferential edge before cutting when the contour of the circumferential edge before cutting and the outline of the circumferential edge after cutting are concentrically superimposed. It is the shortest distance between each position (each point on the circumferential edge) after cutting. The cutting width may be 140 μm or less, 120 μm or less, and 100 μm or less. The cutting width is usually 10 μm or more, and may be 20 μm or more.

Step [a] may be performed several times as long as the cutting width is within the above range. Step [a] is preferably performed two or more times, and may be performed three or more times, and is usually 10 or less, and 5 or less, from the viewpoint of forming a good cutting end surface and efficiently performing cutting. desirable.

In the case of performing step [a] two or more times, the cutting width may be 150 μm or less at any time, and the cutting width at each time may be the same or different. In the case where the step [a] is performed twice or more, for example, first, cutting with a large cutting width may be performed, and then cutting with a small cutting width may be performed.

As described above, in the manufacturing method of the polarizing plate 10, the cutting width per one cut in the cutting performed to form the concave portion 11 is reduced. Thereby, it is possible to suppress the occurrence of long cracks around the concave portion 11 by the condensation heat shock test of the polarizing plate 10. A crack is a cracked gold penetrating or not penetrating the outer surface of the polarizing plate 10 or in the thickness direction, and means that the gap between the cracked cracks is completely open.

The cracks originate from crazes (small cracks in the surface or inside of the polarizing plate 10) present on the surface of the polarizing plate 10 or inside the polarizing plate 10 due to shrinkage of the polarizing plate by a condensation heat shock test. It is presumed to occur. In particular, in the concave portion 11 of the polarizing plate 10, since stress tends to be concentrated due to contraction or expansion of the polarizing plate by the condensation heat shock test, long cracks around the concave portion 11 starting from the craze. It is assumed that it is easy to occur.

From this point of view, in order to reduce the occurrence of long cracks due to the condensation heat shock test, it is considered that it is necessary to suppress the craze generated around the concave portion 11 of the polarizing plate 10. It is estimated that craze is generated by a load applied to the raw material polarizing plate 30 in punching, cutting, cutting, or the like. On the other hand, it is considered that cutting resistance generated by cutting of the raw material polarizing plate 30 can be made relatively small by reducing the cutting width per cut in cutting as described above. In addition, it is considered that the amount of the load accumulated on the polarizing plate according to the cutting process can also be relatively reduced by reducing the cutting width per one cutting process. From this point of view, it is estimated 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-described step [a]. As a result, in the polarizing plate 10 in which the concave portion 11 is formed by reducing the cutting width per shot, it is considered that the occurrence of long cracks due to the condensation heat shock test can be suppressed.

In particular, it is assumed that the polarizing plate 10 having the concave portion 11 is used for a display device of a portable terminal such as a smartphone or a tablet, and in the area of the concave portion 11, a receiver, a speaker, a camera lens, and various kinds of A sensor or the like is placed. In portable terminals such as smartphones and tablets, reducing the width of the frame from the viewpoint of enlargement of the display area and design is in progress. Therefore, in a display device having a relatively wide frame, even if it is a crack of a length that does not cause a problem because it is concealed by a frame, in a display device in which the width of the frame is reduced, it adversely affects the display area. There is. As described above, the polarizing plate 10 in which the occurrence of long cracks due to the condensation heat shock test is suppressed can be suitably used for portable terminals such as smartphones and tablets in which the width of the frame has been reduced.

The raw material polarizing plate 30 in which the concave portion 11 is formed by cutting as shown in FIGS. 3A to 3D is further subjected to cutting, for example, as shown in FIGS. 4A to 4C. By doing so, the polarizing plate 10 can be manufactured. As shown in Fig. 4(a), with respect to the end of the raw material polarizing plate 30 not cut in the steps shown in Figs. 3 (a) to (d), on the end surface of the raw material polarizing plate 30, The cutting portion 52 of the end mill 50 rotating around the rotation shaft 51 is brought into contact, and the peripheral edge portion of the raw material polarizing plate 30 is in a direction indicated by a block arrow in FIG. 4A. Cutting is performed while the end mill 50 is moved relative to each other. Thereby, as shown in FIG. 4(b), the process [b] of forming the peripheral edge part of the polarizing plate 10 other than the concave part 11 is performed. The step [b] may include a step of forming a rounded corner shape (rounded shape) by performing a cutting process so as to chamfer the corners of the raw material polarizing plate 30, as shown in FIG. 4B. Thereby, the polarizing plate 10 in which the concave part 11 was formed in the peripheral edge part shown in FIG. 1 can be obtained (FIG. 4(c)).

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

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

In the cutting process of the 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. 5A and 5B are diagrams for explaining the relationship between the rotational direction and the relative movement direction of the end mill. In the cutting process, as shown in Fig. 5(a), the rotation direction of the end mill 50 at the contact portion between the end surface of the raw material polarizing plate 30 and the cutting portion 52 of the end mill 50 ( The direction indicated by the line arrow in the drawing) may be a so-called up direction, which becomes the same as the relative movement direction of the end mill 50 with respect to the circumferential edge of the raw material polarizing plate 30 (direction indicated by the block arrow in the drawing). It may be the opposite down direction. The down direction is the rotational direction of the end mill 50 at the contact portion between the end surface of the raw material polarizing plate 30 and the cutting portion 52 of the end mill 50, as shown in FIG. 5(b) (Fig. The direction indicated by the middle line arrow) refers to a direction opposite to the direction in which the end mill 50 moves relative to the peripheral edge portion of the raw material polarizing plate 30 (a direction indicated by a block arrow in the drawing). From the viewpoint of shortening the length of the crack generated around the concave portion 11, the step [a] is preferably performed with the rotational direction of the end mill 50 as the up direction.

In the cutting of step [A], the rotational 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, 10000 rpm or more, and 20000 rpm. It may be more than that. The rotational speed of the end mill 50 is usually 60000 rpm or less, 55000 rpm or less, and 50000 rpm or less. When the step [A] includes the step [a] and the step [b], the rotational speed of the end mill 50 may be the same or different in the step [a] and the step [b], and further, the step You may make it partly different during performing [a] and process [b].

In the cutting of step [A], the relative moving speed (feed 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, even if it is 500 m/min or more. It may be 1000 mm/min or more, and it is usually 3000 mm/min or less, 2500 mm/min or less may be sufficient, and 2000 mm/min or less may be sufficient. 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 step [a] and the step [b] They may be the same or different from each other, and may be partially different during the process [a] and the process [b].

The said step [A] may be performed with one raw material polarizing plate 30, and may be performed by laminating two or more raw material polarizing plates 30. In the case of laminating the raw material polarizing plates 30, the number of laminated sheets varies depending on the thickness of the raw material polarizing plates 30, but may be, for example, 10 or more, 20 or more, 30 or more, or 40 or more. , Moreover, it is usually 100 sheets or less, 80 sheets or less may be sufficient, and 60 sheets or less may be sufficient.

The end mills 50 used in the cutting process shown in FIGS. 3A to 3D and the cutting process shown in FIGS. 4A to 4C may be the same or different from each other. When different end mills 50 are used, the types of end mills (shape of the cutting edge, direction or angle of the cutting edge, twist direction or angle of the cutting edge, etc.) may be different. In addition, in the cutting process shown in Figs. 3 (a) to (d) and the cutting process shown in Figs. 4 (a) to (c), the cutting conditions (revolution speed and rotation speed of the endmill) in each cutting process , The relative movement speed, the rotation direction of the end mill, the relative movement direction, etc.) may be the same or different from each other.

In the manufacturing method of the polarizing plate 10 shown in FIGS. 3 (a) to (d) and FIGS. 4 (a) to (c), in FIGS. 3 and 4, along the circumferential edge of the raw material polarizing plate 30 A process in which the end mill 50 moves relative to the counterclockwise direction to perform cutting (Fig. 3 (a) to (d)), and the end mill 50 in a clockwise direction along the circumferential edge of the raw material polarizing plate 30 Although the polarizing plate 10 is manufactured by performing this relative movement and cutting process (FIG. 4(a)-(c)), it is not limited to this. For example, the end mill 50 may move relative to the circumferential edge portion of the raw material polarizing plate 30 in a counterclockwise or clockwise direction, and the raw material polarizing plate 30 may be cut. The starting and ending positions of the raw material polarizing plate 30 are not limited to the positions shown in Figs. 3 (a) and (d) or the positions shown in Figs. 4 (a) and (c). , You can select an arbitrary location.

Further, by dividing the peripheral edge portion of the raw material polarizing plate 30 into two ranges, the process shown in Figs. 3 (a) to (d) and the process shown in Figs. 4 (a) to (c) are used. The method is not limited to the method of performing the cutting process, and the peripheral edge portion of the raw material polarizing plate 30 may be divided into arbitrary ranges, and the cutting processing may be performed in an arbitrary order for each range. Also in this case, the type of the end mill 50 used in each process and the cutting conditions in each process may be the same or different from each other. In addition, cutting in each range may be performed two or more times.

(Polarizing plate)

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 concave portions 11 at the circumferential edges in plan view. For example, as shown in FIG. 6, protective layers 2 and 3 are provided on both sides of the polarizer layer 1. ). The polarizing plate 10 may have only one of the protective layers 2 and 3. The polarizer layer 1 is a polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and oriented. The protective layers 2 and 3 may be a layer formed so as to directly contact the polarizer layer 1, or may be a layer formed through an adhesive layer or an adhesive layer. The polarizing plate 10 does not have a craze at any of the positions of 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 concave portion 11.

The edge within the above arbitrary range is not particularly limited as long as it follows the outline of the concave portion 11 of the polarizing plate 10. It is preferable that the contour of the concave portion 11 is a portion in which the outline of the concave portion 11 is straight over 5 mm or more. When the concave portion 11 of the polarizing plate 10 includes a straight portion and a curved portion, the edge within the arbitrary range is 5 mm in length from the side adjacent (continuous) to the curved portion in the straight portion It is preferable that it is an edge present in the range of.

Specifically, as shown in Fig. 1, the contours of the concave portions 11 of the polarizing plate 10 are formed to face each other, and two sides 11a and 11c each having a linear portion, and the two When connecting the sides (11a, 11c) and having one side (11b) having a straight portion, the position where one of the two sides (11a) and one side (11b) meet (11ab), two sides It is considered that the stress by the moist heat heat shock test tends to be concentrated in the position 11bc where the other side 11c and one side 11b of the inside contact each other and in the vicinity thereof. Therefore, the edge within the above arbitrary range is in a range of 5 mm in length from the side where one of the two sides 11a and 11c and one side 11b are in contact with each other in a straight portion of one side 11b. It is desirable to make it the edge that is present. The linear portion of one side 11b means one of the two sides 11a and 11c and one side when the concave portion 11 has a rounded corner portion, as in the polarizing plate 10 shown in FIG. 1. (11b) It is a straight part excluding the curved part constituting the rounded corner part including the part in contact with (11b).

The contour of the concave portion 11 is the entire circumferential edge portion of a portion of the peripheral edge portion of the polarizing plate 10 that forms the contour of the concave portion 11. The boundary between the portion forming the contour of the concave portion 11 and the portion forming the contour of the peripheral edge portion other than the concave portion 11 is a vertex of the corner portion when the boundary is a corner portion, and the boundary has a rounded corner. In the case (when the corner is rounded), the length of the contour of the rounded corner is divided into two. The edge of the concave portion 11 of the polarizing plate 10 refers to the edge of a portion of the concave portion 11 of the polarizing plate 10 that is the outermost part of the end face (a surface along the thickness direction) in the plane direction. The distance in the plane direction from the edge of the concave portion 11 is a distance in a direction orthogonal to the straight edge in plan view when the edge existing in the arbitrary range is linear. When the edge existing in the 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 measured in the plane direction from the edge of the concave portion 11. Let it be the distance.

The craze is a small crack on the surface or inside of the polarizing plate 10 as described above. As described later, the polarizing plate 10 may have layers other than the polarizer layer 1 and the protective layers 2, 3, but the craze of the polarizing plate 10 means the polarizer layer 1 and the protective layer 2, It refers to what exists in 3). The craze is observed in the cross section of the polarizing plate 10, for example, as shown in Fig. 7A. 7A and 7B are diagrams showing images obtained by observing the cross section of the polarizing plate 10 with a scanning laser microscope. FIG. 7A shows an example of an image when craze exists in the cross section of the polarizing plate 10, and the craze exists in a portion surrounded by a broken line in FIG. 7A. On the other hand, when craze does not exist in the cross-section of the polarizing plate 10, as shown in FIG. 7(b), the part which is surrounded by a broken line in FIG. 7(a) is not recognized.

Polarizing plate 10, in an arbitrary range of 5 mm in length along the contour of the concave portion 11, as described above, of a position of 30 μm and a position of 50 μm in the plane direction from the edge existing in the arbitrary range. Craz is nowhere to be found. In addition, in the polarizing plate 10, a craze may or may not be present at a position of 10 μm in the plane direction from an edge existing in an arbitrary range.

It is estimated that long cracks generated by the condensation heat shock test tend to occur in a direction opposite to the direction of the edge of the concave portion 11 and the direction of the edge, starting from the craze existing in the polarizing plate 10. From this point of view, it is considered that if the craze is present at a position further away from the edge of the concave portion 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 a craze at a position of 30 μm and a position of 50 μm from the edge of the concave portion 11 in the plane direction, the polarizing plate 10 is subjected to a condensation heat shock test. It is thought that the occurrence of long cracks can be suppressed. On the other hand, even if the craze exists at a position of 10 μm in the plane direction from the edge of the concave portion 11 of the polarizing plate 10, it is considered that the crack generated by the condensation heat shock test is short. Therefore, it is thought that it is difficult to adversely affect the display area of a portable terminal such as a smartphone or tablet, but it is preferable that the craze does not exist even at a position of the polarizing plate 10 10 μm in the plane direction from the edge of the concave portion 11. Do.

8A and 8B are schematic plan views schematically showing another example of a polarizing plate. The shape of the polarizing plate 10 in plan view is not particularly limited. For example, it may be a square shape having a concave portion 11 on at least one side or a square shape with rounded corners. A square shape with rounded corners is a rounded corner having a predetermined radius of curvature at least one of the four corners (for example, all four corners) in a square shape, as shown in FIGS. 1 and 8 (a) and (b). It is a shape that is in shape. The square shape is a rectangle shape or a square shape. The planar shape of the polarizing plate 10 is not limited to a square shape, and may be polygonal, circular, or elliptical other than a square shape.

One or more concave portions 11 of the polarizing plate 10 may be provided at the periphery of the polarizing plate 10 in plan view. When the shape of the polarizing plate 10 in plan view is a square shape with rounded corners as shown in FIGS. 1 and 8 (a) and (b), it may have one or more concave portions 11 on at least one side thereof. And, for example, one of the short sides may have a concave portion 11. The concave portions 11 may have two or more on one side, and may have one or more concave portions 11 on two or more sides, respectively.

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

The shape of the concave portion 11 of the polarizing plate 10 is not particularly limited. For example, as shown in FIG. 1, a square shape may be sufficient, as shown in FIG. 8(a), a U shape may be sufficient, and as shown in FIG. 8(b), a V shape may be sufficient. When the concave portion 11 has a rectangular shape, it is not limited to a rectangular shape, and may be a square shape. The concave portion may have a chamfered rounded corner shape. As shown in Fig. 8(b), the top portion (the portion most recessed in the surface direction) of the V-shaped concave portion 11 may be chamfered. Although not shown, the shape of the concave portion 11 of the polarizing plate 10 may be a trapezoid, an arc shape, or a polygonal shape other than a square or a triangle. The shape of the concave portion 11 may be symmetrical or asymmetrical in the left-right direction in the drawing, as shown in FIGS. 1 and 8A and 8B. The contour of the concave portion 11 may be formed into one of a straight portion and a curved portion, and may include both a straight portion and a curved portion.

8A and 8B, when the concave portion 11 is U-shaped and V-shaped, it exists in an arbitrary range of 5 mm in length along the contour of the concave portion 11 It is preferable that the said edge is a part of the straight part of the concave part 11, and it is more preferable that it is an edge which exists in the range of a length of 5 mm from the side adjacent (continuous) to the curved part in the straight part. Specifically, in the polarizing plate 10 shown in FIGS. 8A and 8B, a straight portion adjacent to a curved portion including the top portion (the portion most recessed in the surface direction) of the concave portion 11 In this case, the edge may be set to exist in a range of 5 mm in length from the side adjacent to the curved portion (eg, a portion surrounded by a broken line in the drawing).

It is preferable that the corner portion formed in the concave portion 11 of the polarizing plate 10 is chamfered to have a rounded corner shape (rounded shape). The corner portion formed inside the concave portion 11 is a corner portion that exists outside of the outline of the concave portion 11 and a boundary portion of the circumferential edge other than the concave portion 11 among the corner portions formed in the concave portion 11. Specifically, in the polarizing plate 10 shown in FIG. 1, for example, it is preferable to make the position 11ab and the position 11bc a rounded corner shape. By making the corner part inside the concave part 11 into a rounded corner shape, it becomes easy to suppress the generation|occurrence|production of a crack by the condensation heat shock test in the said part. The outline of the concave portion 11 and the edge portion of the boundary portion of the peripheral edge portion other than the concave portion 11 may also be chamfered and have a rounded corner shape (rounded shape).

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

As described above, the polarizing plate 10 has protective layers 2 and 3 on one or both sides of the polarizer layer 1. When the polarizing plate 10 has protective layers 2 and 3 on both sides of the polarizer layer 1, at the end of the polarizer layer 1, a polarizer layer is provided between the two protective layers 2 and 3 formed on both sides of the polarizer layer 1 Although (1) may be interposed (FIG. 6), it may be directly polymerized without interposing the polarizer layer 1, and the two protective layers 2 and 3 may be fused.

The polarizing plate 10 may further include a pressure-sensitive adhesive layer on the side opposite to the polarizer layer 1 of the protective layers 2 and 3, and additionally on the side opposite to the protective layers 2 and 3 of the pressure-sensitive adhesive layer. A release film may be provided. The pressure-sensitive adhesive layer and the peeling film can be formed 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 from the pressure-sensitive adhesive layer.

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

The polarizing plate 10 may be provided with a protective film on the side opposite to the polarizer layer 1 of the protective layers 2 and 3. The protective film is formed in order to suppress the occurrence of scratches or contamination on the surface of the polarizing plate 10 in manufacturing a product using the polarizing plate 10 or manufacturing or transporting the polarizing plate 10. When the polarizing plate 10 has an optical functional layer, the protective film is formed on the opposite side of the polarizer 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 or an organic EL display device. 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 surfaces of the liquid crystal panel. When applying the polarizing plate 10 to a display device, the polarizing plate 10 is preferably laminated to the image display device through an adhesive layer or an adhesive layer.

(Raw material polarizer)

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. With respect to such a raw material polarizing plate 30, for example, the polarizing plate 10 can be obtained by performing a cutting process in the above-described step [A].

The raw material polarizing plate 30 has a protective layer on one or both sides of the polarizer layer. The polarizer layer is a polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and oriented. The protective layer may be a layer formed so as to directly contact the polarizer layer, or may be a layer formed through an adhesive layer or an adhesive layer. In general, 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 aforementioned pressure-sensitive adhesive layer, an optical functional layer, a protective film, etc. which may be provided in the polarizing plate 10 on one or both sides thereof. When the raw material polarizing plate 30 is provided with the pressure-sensitive adhesive layer, it is preferable that a release film is formed on the side of the pressure-sensitive adhesive layer opposite to the polarizer layer.

The shape of the raw material polarizing plate 30 in plan view is not particularly limited, but it is preferably a shape 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, it is preferable that the raw material polarizing plate 30 also has a concave-shaped notch 31, for example, as shown in Fig. 3A. The corner portions of the raw material polarizing plate 30 and the corner portions of the cutout portions 31 may not be chamfered.

The raw material polarizing plate 30, for example, obtains a long strip-shaped laminate obtained by bonding a long strip-shaped polarizer layer and a long strip-shaped protective layer, and cuts from the laminate in the step [A]. It can be obtained by cutting it into a size that is easy to process. The cutting of the raw material polarizing plate 30 can be performed by punching or cutting. For cutting processing, a blade or a laser can be used. When the raw material polarizing plate 30 has a concave cutout 31, a cutout 31 may be formed on the laminate cut to a predetermined size from the laminate by punching or cutting, and the above laminated The raw material polarizing plate 30 having the cutout 31 may be obtained by punching or cutting a sieve.

Hereinafter, each layer used for the polarizing plate 10 and the raw material polarizing plate will be described in detail.

(Polarizer layer)

The polarizer layer 1 is preferably a film-type polyvinyl alcohol-based resin layer (PVA film) in which a dichroic dye is adsorbed and oriented, produced by processes such as stretching, dyeing and crosslinking. The polarizer layer 1 can be produced by a known method, but can be produced, for example, in the following procedure.

First, a PVA film is stretched in a uniaxial direction or a biaxial direction. The dichroic ratio of the polarizer layer 1 stretched in the uniaxial direction tends to be high. Following stretching, using a dyeing solution, the PVA film is dyed with iodine, a dichroic dye (polyiodine), or an organic dye. The dyeing solution may contain boric acid, zinc sulfate, or zinc chloride. You may wash the PVA film with water before dyeing. By washing with water, the contamination and blocking agent can be removed from the surface of the PVA film. In addition, as a result of the PVA film swelling by washing with water, it is possible to suppress the occurrence of uneven dyeing (uneven dyeing). For crosslinking, the dyed PVA film is treated with a solution of a crosslinking agent (for example, an aqueous solution of boric acid). After treatment with a crosslinking agent, the PVA film is washed with water and then dried. The polarizer layer 1 can be obtained by the above.

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 other monomers (eg, ethylene-vinyl acetate copolymer). Other monomers copolymerized with vinyl acetate include, in addition to ethylene, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, or acrylamides having an ammonium group. 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 dehydration treatment product of polyvinyl alcohol or a dehydrochloric acid treatment 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 polarizer layer 1 can be, for example, 3 to 7 times the length before stretching.

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

(Protective layer)

The protective layers 2 and 3 can be formed using an optically transparent thermoplastic resin having light transmission properties. Resins constituting the protective layers 2 and 3 include chain polyolefin resins, cyclic olefin polymer resins (COP resins), cellulose ester resins, polyester resins, polycarbonate resins, and (meth)acrylic resins. , Polystyrene resins, mixtures thereof, or copolymers thereof. "(Meth)acrylic" means at least one selected from the group consisting of acrylic and methacrylic.

Examples of the chain polyolefin resin include a homopolymer of a chain olefin such as a polyethylene resin or a polypropylene resin. The chain polyolefin resin may be a copolymer composed of two or more types of chain olefins.

As a cyclic olefin polymer resin (cyclic polyolefin resin), a ring-opening (co)polymer of a cyclic olefin or an addition polymer of a cyclic olefin is mentioned, for example. The cyclic olefin polymer resin may be, for example, a copolymer (eg, a random copolymer) of a cyclic olefin and a chain olefin. The chain olefin constituting the copolymer may be, for example, ethylene or propylene. The cyclic olefin polymer resin may be a graft polymer in which the polymer is modified 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 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.

As the polyester resin, a polyester resin other than a cellulose ester resin is mentioned. Examples of such polyester resins include polycondensates of polyhydric carboxylic acids or derivatives thereof and polyhydric alcohols. Examples of the polyhydric carboxylic acid or its derivative include dicarboxylic acid or its derivative, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, or dimethyl naphthalenedicarboxylic acid. Examples of the polyhydric alcohol include diols, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, or cyclohexanedimethanol.

As a specific example of a polyester resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate, or polycyclo Hexane dimethyl naphthalate is mentioned.

The polycarbonate resin is a polymer in which a polymerization unit (monomer) is bonded through 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 (eg, polymethyl methacrylate (PMMA)); Methyl methacrylate-(meth)acrylic acid copolymer; Methyl methacrylate-(meth)acrylic acid ester copolymer; Methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymer; Methyl (meth)acrylate-styrene copolymer (eg, MS resin); A copolymer of methyl methacrylate and a compound having an alicyclic hydrocarbon group (eg, a methyl methacrylate-cyclohexyl methacrylate copolymer, a methyl methacrylate-(meth)acrylate norbonyl copolymer, etc.) can be mentioned.

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, further preferably 200°C or lower, and more preferably 150°C or lower. When the glass transition temperature of the protective layers 2 and 3 is within the above range, heat generated by cutting of the raw material polarizing plate 30 causes the protective layers 2 and 3 formed on both sides of the polarizer layer 1 to be The ends can be fused to each other.

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.

When the polarizing plate 10 has the protective layers 2 and 3 on both surfaces of the polarizer layer 1, the composition of the two protective layers 2 and 3 may be the same or different from each other. When the protective layers 2 and 3 contain a cellulose ester-based resin such as triacetyl cellulose (TAC), it becomes easy to suppress long cracks occurring around the concave portion 11 by a condensation heat shock test. . On the other hand, when the protective layers 2 and 3 contain a cyclic olefin polymer-based resin (COP-based resin), cracks occurring around the concave portions 11 tend to be prolonged by a condensation heat shock test, and The number also tends to increase. The manufacturing method of the polarizing plate is suitable because long cracks can be suppressed even when manufacturing a polarizing plate having the protective layers 2 and 3 containing COP-based resin.

The thickness of the protective layers 2 and 3 may be, for example, 5 μm or more, 10 μm or more, and usually 90 μm or less, and 60 μm or less. When the polarizing plate 10 has the protective layers 2 and 3 on both surfaces of the polarizer 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 films having an optical function. The film having an optical function includes, for example, a retardation film or a brightness improving film. The retardation film can be obtained, for example, by stretching a film made of the 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 polarizer layer 1 through 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 is cured by irradiation with an active energy ray. Examples of active energy rays include ultraviolet rays, visible light, electron rays, or 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 type of resin or may contain a plurality of types of resins. For example, the active energy ray-curable resin may contain a cationic polymerizable curable compound or a radical polymerizable curable compound. The active energy ray-curable resin may contain a cationic polymerization initiator or a radical polymerization initiator for initiating a curing reaction of the curable compound.

Examples of the cationic polymerizable curable compound include an epoxy compound (a compound having at least one epoxy group in the molecule) or an oxetane compound (a compound having at least one oxetane ring in the molecule). Examples of the radical polymerizable curable compound include a (meth)acrylic compound (a compound having at least one (meth)acryloyloxy group in the molecule). Examples of the radically polymerizable curable compound include a vinyl compound having a radically polymerizable double bond.

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, an antifoaming agent, an antistatic agent, a leveling agent or a solvent, if necessary. You may include it.

(Adhesive layer)

The pressure-sensitive adhesive layer exhibits adhesiveness by attaching itself to an adherend, and can be formed from a pressure-sensitive adhesive called a pressure-sensitive adhesive. As the pressure-sensitive adhesive, a known pressure-sensitive adhesive may be used, but examples thereof include 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 pressure-sensitive adhesive layer can be, for example, 2 μm or more and 100 μm or less.

(Peel film)

As described above, the release film is used for the purpose of covering and protecting the pressure-sensitive adhesive layer. The peeling film is peeled off when bonding the polarizing plate 10 to an image display element of a display device or the like. As the release film, a resin film subjected to a release treatment on the side in contact with the pressure-sensitive adhesive layer can be used. As the resin film, a film using a resin exemplified as a resin constituting the protective layers 2 and 3 is exemplified. Silicone coating etc. are mentioned as a mold release process. 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 has an optical function, and may be a film. As an optical functional layer, for example, a retardation film, a reflective polarizing film, a film having an anti-glare function, a film having a surface anti-reflection function, a reflective film, a transflective film, a viewing angle compensation film, a window film, an antistatic layer, a hard coat Layer, optical compensation layer, touch sensor layer, antifouling layer, etc. are mentioned. One or two 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 have a pressure-sensitive adhesive layer on the base film, or may be a self-adhesive film. As a resin used for the base film of a protective film, the resin used for the said protective layers 2, 3 is mentioned, As an adhesive layer, the said adhesive is mentioned. The self-adhesive film can be formed using, for example, a polypropylene resin, a polyethylene resin, or the like.

Example

Hereinafter, the present invention is more specifically described by showing examples and comparative examples, but the present invention is not limited by these examples.

[Condensation heat shock test]

Using the polarizing plates obtained in Examples and Comparative Examples, the following steps 1 to 3 were performed in this order as 1 cycle, and a condensation heat shock test was performed in which this was continuously repeated 10 cycles.

· Step 1:

The polarizing plate is held for 30 minutes in an environment at a temperature of -40°C and a relative humidity of 11% RH.

· Step 2:

The polarizing plate which performed Step 1 is held for 5 minutes in an environment at a temperature of 23° C. and a relative humidity of 9% RH.

· Step 3:

The polarizing plate on which Step 2 was performed is held for 30 minutes in an environment at a temperature of 85° C. and a relative humidity of 7% RH.

With respect to the polarizing plate subjected to the condensation heat shock test, the periphery of the concave portion was observed with an optical microscope in plan view. For the polarizing plates obtained in Examples and Comparative Examples, among the cracks generated near the positions 11ab and 11bc of the concave portion 11 shown in FIG. 1, the one having the longest length in the long side direction of the polarizing plate was measured. And this was taken as the length of the crack in the curved portion of the concave portion. In addition, in Example 2 and Comparative Example 3, in the straight portion of the side 11b of the concave portion 11 shown in Fig. 1, the range of a length of 5 mm from the side where the side 11a and the side 11b are in contact. The length of the long side direction of the polarizing plate of cracks occurring near the edge existing in the edge, and the edge existing in the range of 5 mm from the side contacting the side 11b and the side 11c, was also measured, and among the measured cracks , The longest length of the polarizing plate in the direction of the long side was taken as the crack length in the straight portion of the concave portion.

[Example 1]

A protective layer formed using a 52 μm-thick cyclic olefin polymer resin on one side of an 8 μm-thick polarizer layer produced by stretching and dyeing a polyvinyl alcohol film using a polyvinyl alcohol-based adhesive (water-based adhesive) Was joined. On the other side of the polarizer layer, a protective layer formed using a 21 μm-thick cyclic olefin polymer resin is bonded to the other side of the polarizer layer, and the UV curable epoxy resin is cured by irradiation with ultraviolet rays. And a protective layer having a thickness of 21 μm was deposited. On a protective layer having a thickness of 52 μm, a protective film (thickness 58 μm) having an adhesive layer formed on a base film is bonded, and on a protective layer having a thickness of 21 μm, an adhesive layer having a thickness of 20 μm and a release film (thickness 38 μm) Were laminated in this order to obtain a rectangular laminate. In this laminate, the thickness of the laminated structure from the 52 μm protective layer to the pressure-sensitive adhesive layer is 102 μm, and a 58 μm-thick protective film is provided on one side of the laminated structure and a 38 μm-thick release film is on the other side. Each of these was stacked. In addition, in the obtained laminate, the polarizer layer and the protective layer having a thickness of 21 μm bonded to the other side (a protective layer having a thickness of 21 μm formed using a cyclic olefin polymer resin) is an adhesive layer that is a cured product of a UV-curable epoxy resin. It was adhered through (thickness 1 μm). The obtained laminate was punched using a pinnacle blade to produce 47 raw material polarizing plates having the shape shown in Fig. 3A.

In a state in which 47 raw material polarizing plates were stacked so that the release film side of the raw material polarizing plate was at the lower side, it was placed on a mounting table of a cutting device, and fixed to the mounting table by a clamp. The end mill (DXL-4, manufactured by Nisshin Tools Co., Ltd., diameter: 4 mm, right edge, cutting angle β: 65 [°]) attached to the cutting device was rotated, and the end face of the raw material polarizing plate laminated with the cutting part of the end mill ( It was brought into contact with the surface along the lamination direction), and cutting was performed three times while moving the end mill relative to the raw material polarizing plate in plan view. In each cutting process, the cutting width was set to 100 μm, the rotation speed of the end mill was set to 30000 rpm, and the feed rate (relative moving speed) of the end mill was set to 1000 mm/min, and the cutting was performed in the up direction.

By the cutting process, as shown in Fig. 1, a rectangular polarizing plate having a rectangular concave portion was obtained. 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 concave portion 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. About the obtained polarizing plate, the condensation heat shock test was performed, and the crack length in the curved part of a concave part was measured. Table 1 shows the results.

[Comparative Example 1]

A polarizing plate was obtained in the same manner as in Example 1, except that cutting was performed twice and the cutting width at each time was as shown in Table 1. About the obtained polarizing plate, the condensation heat shock test was performed, and the crack length in the curved part of a concave part was measured. Table 1 shows the results.

[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 set as shown in Table 2. In the linear portion of the side 11b of the concave portion of the polarizing plate obtained above, the polarizing plate was cut out so that the length of 5 mm from the side in contact with the side 11a of the side 11b became one side to obtain a sample for measurement. The end face (face along the thickness direction) of the one side of the cut-out measurement sample is cut using a microtome, and a position of 10 μm, a position of 30 μm, and a position of 50 μm from the edge of the end surface to the surface direction. The cross section of was observed with a scanning laser microscope (observation magnification: 100 times) to confirm the presence or absence of craze. Table 2 shows the results.

Further, the obtained polarizing plate was subjected to a condensation heat shock test, and the crack length in the curved portion of the concave portion and the crack length in the straight portion were measured. Table 2 shows the results.

[Comparative Example 2]

About the raw material polarizing plate obtained in Example 1, in the same procedure as Example 2, the presence or absence of craze was confirmed. Further, using the raw material polarizing plate obtained in Example 1, a condensation heat shock test was performed, and the crack length in the curved portion of the concave portion was measured. The results are shown in Tables 1 and 2.

[Comparative Example 3]

Except having made the cutting width as shown in Table 2, it carried out similarly to Example 2, and obtained the polarizing plate. Regarding the obtained polarizing plate, the presence or absence of craze was confirmed in the same procedure as in Example 2. Further, the obtained polarizing plate was subjected to a condensation heat shock test to measure the crack length in the curved portion of the concave portion and the crack length in the straight portion. Table 2 shows the results.

1: polarizer layer, 2: protective layer, 3: protective layer, 10: polarizing plate, 11: concave portion, 11a, 11b, 11c: side, 11ab, 11bc: position, 30: raw material polarizing plate, 31: notched portion, 50: End mill, 51: rotating shaft, 52: cutting part, 52a: cutting edge.

Claims (11)

As a method of manufacturing a polarizing plate having a concave portion at the circumferential edge in plan view,
A step of preparing a raw material polarizing plate having a protective layer on one or both sides of the polarizer layer, and
A step [a] of performing cutting to form the concave while moving the end mill relative to the circumferential edge of the raw material polarizing plate,
The cutting process in the step [a] is a cutting process in which the cutting width is 150 μm or less. The method of manufacturing a polarizing plate according to claim 1, wherein the raw material polarizing plate has a concave cutout in a region in which the concave portion is formed. The method for manufacturing a polarizing plate according to claim 1 or 2, wherein the step [a] is performed two or more times. The method according to any one of claims 1 to 3, further comprising cutting an end mill to form a peripheral edge portion of the polarizing plate other than the concave portion while moving the end mill relative to the peripheral edge portion of the raw material polarizing plate. The manufacturing method of a polarizing plate including step [b]. 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 manufacturing a polarizing plate according to any one of claims 1 to 5, wherein the polarizer layer is a polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and oriented. A polarizing plate having a concave portion at the peripheral edge in plan view
The polarizing plate has a protective layer on one or both sides of the polarizer layer,
A polarizing plate in which craze does not exist either at a position of 30 μm and a position of 50 μm in the plane direction from an edge existing in an arbitrary range of 5 mm in length along the contour of the concave portion. The polarizing plate according to claim 7, further comprising a craze or no craze at a position of 10 μm in the plane direction from an edge existing in the arbitrary range. The method according to claim 7 or 8,
The contour of the concave portion has a curved portion and a straight portion,
The edge existing in the arbitrary range is a polarizing plate that is an edge in the linear portion and in a length of 5 mm from a side adjacent to the curved portion. The method according to any one of claims 7 to 9, wherein the contour of the concave portion is formed to face each other and has two sides each having a straight portion, and 1 connecting the two sides and having a straight portion. Including the dog's stool,
The edge existing in the arbitrary range is a polarizing plate that is an edge that is in a range of 5 mm in length from a side where one side of the one side and one of the two sides are in contact with each other in the linear portion of the one side. The polarizing plate according to any one of claims 7 to 10, wherein the polarizer layer is a polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and oriented.

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