TW202311788A - Polarizing plate, and method for manufacturing the same capable of suppressing contamination of the polarizing plate caused by dichroic pigments in a polarizing element layer - Google Patents

Abstract

The present invention provides a polarizing plate that suppresses a contamination of the polarizing plate caused by dichroic pigments in a polarizing element layer. The polarizing plate 20 is provided with a polarizing element layer 5. The polarizing element layer 5 contains a polymer of a polymerizable liquid crystal compound and a dichroic pigment. The polarizing element layer 5 includes an outer periphery portion 5P including an end surface 5E substantially parallel to the thickness direction of the polarizing element layer 5. A central portion 5C is surrounded by the outer peripheral portion 5P. The concentration of the dichroic pigment in a part of or the entire outer peripheral portion 5P is lower than that in the central portion 5C.

Description

Polarizing plate, and method for manufacturing polarizing plate

The invention relates to a polarizing plate and a manufacturing method of the polarizing plate.

Polarizing plates are used in image display devices (organic EL (Electroluminescence, electroluminescence) displays, liquid crystal displays, etc.) of TVs, computers, smart phones, smart watches, portable game consoles, or instrument panels of vehicles. A polarizing plate is manufactured by laminating multiple layers such as a protective layer (protective film), a polarizer layer, an adhesive layer, and a retardation layer. As a polarizing element layer different from conventional stretched polyvinyl alcohol films, a polarizing element layer containing a polymer of a polymerizable liquid crystal compound and a dichroic dye is known. (Refer to the following patent documents 1 to 3) [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2017-83843 [Patent Document 2] International Publication No. 2020/122117 [Patent Document 3] International Publication No. 2020/179864

[Problem to be solved by the invention]

In the production process of a polarizing plate using a polarizer layer containing a polymer containing a polymerizable liquid crystal compound and a dichroic dye, a laminate is formed by laminating the polarizer layer with one or more other laminated layers. The end surface of the polarizer layer is exposed on the end surface of the laminated body. Since the end face of the polarizing element layer is in contact with manufacturing equipment such as jigs or packaging materials for polarizing plates, the dichroic pigment in the polarizing element layer will detach from the end face of the polarizing element layer and adhere to the manufacturing equipment or packing materials . Dichroic dyes attached to manufacturing equipment or packaging materials to contaminate laminates (semi-finished products) or polarizers (finished products). Also, since the plurality of laminates (semi-finished products) including the polarizer layer are in contact with each other during the manufacturing process, the plurality of laminates are mutually contaminated with the dichroic dye from the polarizer layer. Due to such contamination, the quality of the polarizing plate is impaired.

An object of an aspect of the present invention is to provide a polarizing plate that suppresses contamination of the polarizing plate caused by a dichroic dye in a polarizing element layer, and a method for manufacturing the polarizing plate. [Technical means to solve the problem]

A polarizing plate according to an aspect of the present invention has a polarizing element layer. The polarizing element layer contains a polymer of a polymerizable liquid crystal compound and a dichroic dye. The polarizing element layer includes: an end surface substantially parallel to the thickness direction of the polarizing element layer In the outer peripheral part and the central part surrounded by the outer peripheral part, the concentration of the dichroic dye in a part or the whole of the outer peripheral part is lower than the concentration of the dichroic dye in the central part.

A polarizing plate according to an aspect of the present invention may include a first protective layer laminated directly or indirectly on one surface of the polarizing element layer.

The first protective layer may have an end surface substantially parallel to the thickness direction of the first protective layer, and the end surface of the first protective layer and the end surface of the polarizer layer may be included in the same plane.

The polarizing plate according to one aspect of the present invention may include a second protective layer directly or indirectly laminated on the other surface of the polarizing element layer.

The second protective layer may have an end surface substantially parallel to the thickness direction of the second protective layer, and the end surface of the second protective layer and the above-mentioned end surface of the polarizer layer may be included in the same plane.

A part or the whole of the end surface of the polarizer layer may be covered with a film containing polyvinyl alcohol.

The thickness of the outer peripheral portion of the polarizing element layer may be approximately equal to the thickness of the central portion of the polarizing element layer.

The polarizing plate according to an aspect of the present invention may have an end surface substantially parallel to the thickness direction of the polarizing plate, and the end surface of the polarizing element layer may be exposed on the end surface of the polarizing plate.

An image display device according to an aspect of the present invention includes the above-mentioned polarizing plate.

The method of manufacturing a polarizing plate according to the first aspect of the present invention is a method of manufacturing the above-mentioned polarizing plate. The method for producing a polarizing plate according to the first aspect of the present invention includes: a step of producing a laminate including a polarizing element layer containing a polymer of a polymerizable liquid crystal compound and a dichroic dye; The step of attaching the solvent of the dichroic pigment to the knife and cutting the laminate with the knife, or the step of cutting the laminate with the knife while spraying the solvent capable of dissolving the dichroic pigment to the knife.

The method for producing a polarizing plate according to the first aspect of the present invention may further include a step of drying the cut surface of the cut laminate.

The manufacturing method of the polarizing plate of the 2nd aspect of this invention is the method of manufacturing the above-mentioned polarizing plate. The method for manufacturing a polarizing plate according to the second aspect of the present invention includes: a step of producing a first laminate including a polarizing element layer containing a polymer of a polymerizable liquid crystal compound and a dichroic dye; A step of producing a plurality of second laminates from the first laminate; a step of producing a third laminate by overlapping the plurality of second laminates; and at least one of the end faces of the third laminated body, a step of grinding the end face of the third laminated body with a knife.

The method of manufacturing a polarizing plate according to the second aspect of the present invention may further include a step of drying the polished end surface of the third laminate.

The manufacturing method of the polarizing plate of the 3rd aspect of this invention is the method of manufacturing the above-mentioned polarizing plate. The method for manufacturing a polarizing plate according to the third aspect of the present invention includes: a step of producing a laminate including a polarizing element layer containing a polymer of a polymerizable liquid crystal compound and a dichroic pigment; The step of spraying and attaching the solvent of the dichroic pigment to the end surface of the laminate, and cleaning the end surface of the laminate with dry ice and snow, or after attaching the solvent capable of dissolving the dichroic pigment to the end surface of the laminate, cleaning the end surface of the laminate with dry ice and snow The step of cleaning the end face of the laminated body.

The method of manufacturing a polarizing plate according to the third aspect of the present invention may further include a step of drying the cleaned end surface of the laminate.

The manufacturing method of the polarizing plate of the 4th aspect of this invention is the method of manufacturing the above-mentioned polarizing plate. The method for manufacturing a polarizing plate according to the fourth aspect of the present invention includes: a step of producing a plurality of laminates, the plurality of laminates include a polarizing element layer having the same size and laminated structure as the polarizing plate, and the polarizing element layer contains a polymerizable liquid crystal Compound polymers and dichroic pigments; the step of applying a solvent capable of dissolving dichroic pigments to the end surfaces of multiple overlapping laminates; wiping off the solvent applied to the end surfaces of multiple overlapping laminates and a step of bundling the plurality of laminates that have been wiped off of the solvent.

The method for manufacturing a polarizing plate according to the fourth aspect of the present invention may further include a step of drying the end faces of the plurality of laminates from which the solvent has been wiped off before packaging the plurality of laminates. [Effect of Invention]

According to one aspect of the present invention, there are provided a polarizing plate that suppresses contamination of the polarizing plate due to a dichroic dye in a polarizing element layer, and a method for manufacturing the polarizing plate.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, the same symbols are attached to the same components. The present invention is not limited to the following embodiments. X, Y, and Z shown in each figure refer to three coordinate axes orthogonal to each other. The directions indicated by the XYZ coordinate axes in each figure are common to all figures. The X-axis direction can also be referred to as the longitudinal direction of the polarizing plate and the longitudinal direction of each layer (polarizing element layer, etc.) included in the polarizing plate. The Y-axis direction may also be referred to as the width direction of the polarizing plate and the width direction of each layer (polarizing element layer, etc.) included in the polarizing plate. The Z-axis direction can also be referred to as the layering direction (thickness direction) of the polarizing plate and the thickness direction of each layer (polarizing element layer, etc.) included in the polarizing plate.

(Overview of Polarizing Plate) The polarizing plate of this embodiment includes at least a polarizing element layer. The polarizer layer contains a polymer of a polymerizable liquid crystal compound and a dichroic dye. The polarizing plate may be a laminate including a polarizing element layer and one or more other layers laminated directly or indirectly on the polarizing element layer. For example, the polarizer may have a first protective layer laminated directly or indirectly on one surface of the polarizer layer. The polarizing plate may have a second protective layer laminated directly or indirectly on the other surface of the polarizing element layer. The damage of the polarizing element layer is suppressed by protecting the polarizing element layer with one or both of the first protective layer and the second protective layer. Furthermore, by one or both of the first protective layer and the second protective layer, the diffusion of the dichroic dye from the polarizer layer to other layers is suppressed. When any two layers constituting the polarizing plate are described as A layer and B layer, the so-called B layer directly laminated on the A layer refers to the B layer laminated on the A layer without intervening other layers. The so-called layer B that is indirectly laminated on the layer A refers to the layer B that is laminated on the layer A through other layers.

FIG. 1 shows an example of the laminated structure of the polarizing plate of this embodiment. The polarizing plate 20 shown in Fig. 1 can have: the first protective layer 3, the alignment layer 4 that is directly laminated on the surface of the first protective layer 3, the polarizer layer 5 that is directly laminated on the surface of the alignment layer 4, directly laminated on the The second protective layer 6 on the surface of the polarizer layer 5, the first adhesive layer 7 directly laminated on the surface of the second protective layer 6, the retardation layer 8 directly laminated on the surface of the first adhesive layer 7, the direct laminate The second adhesive layer 9 on the surface of the phase difference layer 8, the optical compensation layer 10 (another phase difference layer) directly laminated on the surface of the second adhesive layer 9, and the optical compensation layer directly laminated on the surface of the optical compensation layer 10 The third protective layer 11. However, the laminated structure of the polarizing plate is not limited to the laminated structure shown in FIG. 1 . The shape of the polarizing plate 20 and each layer in a direction substantially perpendicular to the stacking direction of the polarizing plate 20 (thickness direction of the polarizing element layer 5 ) can be approximately the same as the shape of the screen of the image display device. For example, the shape of the polarizing plate 20 and each layer in a direction substantially perpendicular to the stacking direction of the polarizing plate 20 (thickness direction of the polarizing element layer 5 ) may be rectangular (rectangular or square). However, the shape of the polarizing plate 20 and each layer in a direction substantially perpendicular to the stacking direction of the polarizing plate 20 (thickness direction of the polarizing element layer 5 ) is not limited. One or more notches (notches) may be formed at the end of the polarizing plate 20 . It is also possible to form more than one through hole in the polarizer 20 .

As shown in FIGS. 1 and 2 , the polarizer layer 5 includes: an outer peripheral portion 5P including an end face 5E substantially parallel to the thickness direction (Z-axis direction) of the polarizer layer 5; and a central portion 5C formed by the outer peripheral portion 5P. surrounded. The polarizing plate 20 may have an end surface substantially parallel to the thickness direction (lamination direction) of the polarizing plate 20, and the end surface 5E of the polarizing element layer 5 may be exposed on the above-mentioned end surface of the polarizing plate. On the other hand, since the central portion 5C of the polarizing element layer 5 is surrounded by the outer peripheral portion 5P, the central portion 5C of the polarizing element layer 5 is not exposed on the above-mentioned end surface of the polarizing plate 20 .

The concentration of the dichroic dye in a part or the whole of the peripheral portion 5P is lower than that in the central portion 5C. As a result, even when the end surface 5E of the polarizing element layer 5 is in contact with manufacturing equipment such as jigs or packaging materials for polarizing plates, the dichroic dye in the polarizing element layer 5 can be suppressed from polarizing the element. The end face 5E of the layer 5 is detached and attached to the manufacturing equipment or packing material. Therefore, contamination of the laminate (semi-finished product) or the polarizing plate (product) by the dichroic dye adhering to the manufacturing equipment or packaging material can be suppressed. Even when the end surface 5E of the polarizing element layer 5 contained in the laminate (semi-finished product) is in contact with other laminates (semi-finished product), since the concentration of the dichroic dye in the outer peripheral portion 5P is lower than that of the dichroic dye in the central portion 5C. The concentration of the dichroic dye can also be suppressed from adhering the dichroic dye from the polarizer layer 5 of one laminate to the other laminate (semi-finished product). Therefore, it is possible to prevent the plurality of laminates from being contaminated by the dichroic dye from the polarizer layer 5 . For these reasons, according to the present embodiment, the contamination of the polarizing plate due to the dichroic dye is suppressed, and the quality of the polarizing plate is improved.

The magnitude relationship of the concentration of the dichroic dye between the peripheral portion 5P and the central portion 5C can be specified by the following method. The polarizing plate 20 of this embodiment is attached to one surface of the non-alkali glass plate. Another polarizing plate comprising a polarizing element layer with a uniform concentration of dichroic pigments is bonded to the other surface of the non-alkali glass plate. The orientations of the polarizer 20 and the other polarizer are adjusted so that the polarizer 20 and the other polarizer become crossed polarizers. By the above method, a sample was produced. An image of the entire surface of the polarizing plate 20 of the present embodiment among the surfaces of the above-mentioned samples was photographed with an optical microscope. For example, as an optical microscope, "VHX-500" manufactured by KEYENCE CORPORATION can be used. Based on the average value of the RGB (Red Green Blue) values of the image of the polarizer 20, the image of the entire surface of the polarizer 20 is converted into monochrome (gray scale) including 256 tones (0-255) The pixel image. For example, "ImageJ" which is an image analysis software (free software) can be used for image conversion. In the image of the polarizing plate 20 , the part with a larger tone value is brighter than the part with a smaller tone value in the image of the polarizing plate 20 . In the image of the polarizing plate 20, the gradation value of the portion overlapping with the outer peripheral portion 5P of the polarizing element layer 5, which has a lower concentration of the dichroic dye, is greater than that of the image of the polarizing plate 20, which has a higher density of the dichroic dye. The gradation value of the portion where the central portion 5C of the polarizer layer 5 overlaps. Therefore, in the image of the polarizing plate 20, the portion overlapping with the outer peripheral portion 5P of the polarizing element layer 5 with a lower concentration of the dichroic dye is more polarized than the portion of the image of the polarizing plate 20 with a higher concentration of the dichroic dye. The overlapping portion of the central portion 5C of the element layer 5 is bright. A curve of the tone value is drawn along the direction perpendicular to the portion of the outline of the image of the polarizing plate 20 that overlaps the end surface 5E of the polarizing element layer 5 . That is, the origin of the horizontal axis of the curve of the tone value corresponds to the position of the end surface 5E of the polarizer layer 5 , and the value of the horizontal axis corresponds to the distance from the end surface 5E of the polarizer layer 5 . The curve of the gradation value may include: a first region, which is continuous with the vertical axis (the end surface 5E of the polarizer layer 5), and the gradation value is relatively large and substantially fixed; a second region, which is continuous with the first region, and , the tone value gradually decreases; and the third area, which is continuous with the second area, and the tone value is small and approximately constant. The value of the horizontal axis corresponding to the middle point of the second region may be the width W of the outer peripheral portion 5P in a direction substantially perpendicular to the thickness direction (Z-axis direction) of the polarizer layer 5 . For example, the width W of the outer peripheral portion 5P may be 5 μm to 50 μm, 5 μm to 30 μm, or 5 μm to 20 μm. The larger the width W of the peripheral portion 5P, the less likely the dichroic dye will be detached from the end surface 5E of the polarizer layer 5, and the easier it is to suppress contamination caused by the dichroic dye. However, as the width W of the outer peripheral portion 5P increases, the central portion 5C having polarization energy becomes narrower.

The unit of the concentration of a dichroic dye may be parts by mass, for example. For example, the concentration (mass ratio) of the dichroic dye in a part or the whole of the outer peripheral portion 5P of the polarizing element layer 5 may be 0 mass part or more and less than 1 mass part with respect to 100 mass parts of the polymer of the polymerizable liquid crystal compound. parts by mass. The concentration of the dichroic dye in the central portion 5C of the polarizing element layer 5 may be 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polymer of the polymerizable liquid crystal compound. The quantitative correlation (such as a calibration curve) between the gradation value in the image of the polarizing plate 20 and the concentration of the dichroic pigment in the polarizer layer 5 can be determined in advance, and can be specified by the gradation value in the peripheral portion 5P. Concentration of dichroic pigments in peripheral portion 5P. Likewise, the concentration of the dichroic dye in the central portion 5C can be specified from the gradation value in the central portion 5C. The concentration of dichroic pigments can also be referred to as the content of dichroic pigments.

The first protective layer 3 may have an end surface substantially parallel to the thickness direction (Z-axis direction) of the first protective layer 3, and the above-mentioned end surface of the first protective layer 3 and the end surface 5E of the polarizer layer 5 may be included in the same plane (polarizer 20 one end face). The second protective layer 6 may have an end surface substantially parallel to the thickness direction (Z-axis direction) of the second protective layer 6, and the end surface of the second protective layer 6 and the end surface 5E of the polarizer layer 5 may be included in the same plane (polarizer 20 one of the ends). The above-mentioned end surface of the first protective layer 3 , the end surface 5E of the polarizer layer 5 , and the above-mentioned end surface of the second protective layer 6 may all be included in the same plane (one end surface of the polarizer 20 ). The outer peripheral portion 5P of the polarizer layer 5 is not easily deformed (contracted) as the concentration of the dichroic dye in the outer peripheral portion 5P of the polarizer layer 5 decreases. That is, the position of the end surface 5E of the polarizing element layer 5 is less likely to change as the concentration of the dichroic dye in the outer peripheral portion 5P of the polarizing element layer 5 decreases. Therefore, regardless of the change in the concentration of the dichroic dye in the peripheral portion 5P, the respective end faces of the first protective layer 3, the polarizing element layer 5, and the second protective layer 6 are easily included in the same plane (one end face of the polarizing plate 20). ). Assuming that the depolarized portion is formed along the outer peripheral portion 5P of the polarizing element layer 5 by heating or cutting using a laser such as a CO ₂ gas laser, in this case, the outer peripheral portion 5P of the polarizing element layer 5 Easily expands or contracts due to heat. The position of the end surface 5E of the polarizer layer 5 is likely to change due to the expansion or contraction of the outer peripheral portion 5P. As a result, it is difficult to align the position of the end surface 5E of the polarizer layer 5 with the positions of the respective end surfaces of the first protective layer 3 and the second protective layer 6 . That is, when the previous depolarizing portion is formed along the outer peripheral portion 5P of the polarizing element layer 5, it is difficult to include the respective end faces of the first protective layer 3, the polarizing element layer 5, and the second protective layer 6 on the same plane (polarized light one end face of plate 20). For the above reasons, the outer peripheral portion 5P of the polarizing element layer 5 where the concentration of the dichroic dye is reduced is different from the conventional depolarizing portion.

The thickness of the outer peripheral portion 5P of the polarizer layer 5 may be approximately equal to the thickness of the central portion 5C of the polarizer layer 5 . The outer peripheral portion 5P of the polarizing element layer 5 is not easily deformed as the concentration of the dichroic dye in the outer peripheral portion 5P of the polarizing element layer 5 decreases. That is, the thickness of the polarizing element layer 5 is less likely to change as the concentration of the dichroic dye in the outer peripheral portion 5P of the polarizing element layer 5 decreases. Therefore, the thickness of the peripheral portion 5P where the concentration of the dichroic dye is low tends to be approximately equal to the thickness of the central portion 5C where the concentration of the dichroic dye is high. Assuming that the depolarized portion is formed along the outer peripheral portion 5P of the polarizing element layer 5 by heating or cutting using a laser such as a CO ₂ gas laser, in this case, the outer peripheral portion 5P of the polarizing element layer 5 Easily expands or contracts due to heat. That is, the thickness of the outer peripheral portion 5P of the polarizing element layer 5 tends to change with the formation of the previous depolarization portion along the outer peripheral portion 5P. Therefore, the thickness of the peripheral portion 5P formed with the previous depolarizing portion tends to be different from the thickness of the central portion 5C without the depolarizing portion. For the above reasons, the outer peripheral portion 5P of the polarizing element layer 5 where the concentration of the dichroic dye is reduced is different from the conventional depolarizing portion.

A part or the whole of the end surface 5E of the polarizer layer 5 may be covered with a film containing polyvinyl alcohol (for example, a film composed of polyvinyl alcohol). With the film containing polyvinyl alcohol, it is easy to suppress the detachment of the dichroic dye from the end surface 5E of the polarizing element layer 5 .

The image display device of the present embodiment includes the polarizing plate 20 described above. For example, the image display device may be an organic EL display including the above-mentioned polarizer 20 and an organic EL display element (organic EL panel) on which the polarizer 20 is directly or indirectly laminated. The image display device may also be a liquid crystal display including the above-mentioned polarizing plate 20 and a liquid crystal display element (liquid crystal display panel) on which the polarizing plate 20 is directly or indirectly laminated.

For example, the thickness of the first protective layer 3 may be 0.1 μm to 13 μm, 0.3 μm to 8 μm, or 0.5 μm to 5 μm. For example, the thickness of the alignment layer 4 may be 10 nm to 5000 nm, 10 nm to 1000 nm, 10 nm to 500 nm, or 10 nm to 300 nm. For example, the thickness of the polarizer layer 5 may be 0.5 μm to 10 μm, 0.5 μm to 8 μm, or 1 μm to 5 μm. For example, the thickness of the second protective layer 6 may be 0.1 μm to 13 μm, 0.3 μm to 8 μm, or 0.5 μm to 5 μm. For example, the thickness of the first adhesive layer 7 may be 0.1 μm to 15 μm, 0.5 μm to 10 μm, or 1 μm to 5 μm. For example, the thickness of the retardation layer 8 may be 0.1 μm to 10 μm, 0.5 μm to 8 μm, or 1 μm to 6 μm. For example, the thickness of the second adhesive layer 9 may be 0.1 μm to 15 μm, 0.5 μm to 10 μm, or 1 μm to 5 μm. For example, the thickness of the optical compensation layer 10 may be 0.1 μm to 10 μm, 0.5 μm to 8 μm, or 1 μm to 6 μm. For example, the thickness of the third protective layer 11 may be not less than 5 μm and not more than 100 μm. The thickness of each layer can be substantially uniform. In other words, the thickness of the layer can be substantially uniform throughout any portion of the layer.

(Manufacturing method of polarizing plate) An example of a method for producing a polarizing plate may include: a step of producing a laminate including a polarizing element layer 5 containing a polymer of a polymerizable liquid crystal compound and a dichroic dye; and making the soluble dichroic dye After the solvent is attached to the knife, the step of cutting the laminate with the knife, or the step of cutting the laminate with the knife while spraying the solvent that can dissolve the dichroic pigment to the knife. In the step of cutting the laminated body with a knife, both end portions of a pair of laminated bodies facing in the width direction of the laminated body may be cut off. Solvent can be applied to the knife. In the step of cutting the laminated body with a knife, at least a part of the dichroic dye contained in the outer peripheral portion 5P of the polarizing element layer 5 oozes out into the solvent, and the dichroic dye is released from the laminated body as the laminated body is cut. body removal. As a result, the concentration of the dichroic dye in the peripheral portion 5P becomes lower than the concentration of the dichroic dye in the central portion 5C. For example, the solvent that can dissolve the dichroic dye can be water (warm water), or ethanol diluted with water. For example, the blade used for cutting the laminate may be a strip cutter. The laminate to be cut by a knife may have the same laminate structure as that of the polarizing plate 20 described above. The laminate for knife cutting may also include: the first protective layer 3 , the alignment layer 4 directly laminated on the surface of the first protective layer 3 , and the polarizer layer 5 directly laminated on the surface of the alignment layer 4 . The method for producing a polarizing plate may further include a step of drying the cut surface of the cut laminate. The drying method can be warm air. The method of manufacturing a polarizing plate may include a step of wiping off the solvent remaining on the cut surface of the cut laminate. Through these steps, it is easy to reliably remove the dichroic dye remaining on the cut surface of the cut laminate.

Another example of the method of manufacturing a polarizing plate may include: a step of producing a first laminate including a polarizing element layer 5 containing a polymer of a polymerizable liquid crystal compound and a dichroic dye; a step of manufacturing a plurality of second laminates by stacking the plurality of second laminates; a step of manufacturing a third laminate by overlapping the plurality of second laminates; A step of grinding (cutting) the end face of the third laminate on one side of at least one of the end faces of the three laminates with a knife. In the step of grinding the end face of the third laminate with a knife, at least a part of the dichroic dye contained in the outer peripheral portion 5P of the polarizer layer 5 seeps out into the solvent, and as the end face of the third laminate is ground, both The chromatic pigment is removed from the third laminate. As a result, the concentration of the dichroic dye in the peripheral portion 5P becomes lower than the concentration of the dichroic dye in the central portion 5C. For example, the blade used for grinding the end face of the third laminate may be an end mill or a disc-shaped rotary blade. Each of the first laminate and the second laminate may have the same laminate structure as that of the polarizing plate 20 described above. The size of the second layered body in a direction substantially perpendicular to the layered direction may be substantially the same as the size of the polarizing plate 20 in this direction. The method of manufacturing a polarizing plate may further include a step of drying the polished end surface of the third laminate. The drying method can be water temperature wind. The method of manufacturing a polarizing plate may include a step of wiping off the solvent remaining on the polished end face of the third laminate. Through these steps, it is easy to reliably remove the dichroic dye remaining on the polished end surface of the third laminate.

Another example of the method of manufacturing a polarizing plate may include: a step of producing a laminate including a polarizing element layer 5 containing a polymer of a polymerizable liquid crystal compound and a dichroic pigment; The step of spraying and attaching the solvent of the pigment to the end surface of the laminate, and cleaning the end surface of the laminate with dry ice and snow, or after attaching the solvent capable of dissolving the dichroic pigment to the end surface of the laminate, cleaning with dry ice and snow The step of the end face of the laminated body. The solvent can be applied to the end face of the laminate. In the step of cleaning the end face of the laminate with dry ice and snow, at least a part of the dichroic dye contained in the outer peripheral portion 5P of the polarizing element layer 5 bleeds into the solvent, and the dichroic dye is removed from the laminate by the dry ice. As a result, the concentration of the dichroic dye in the peripheral portion 5P becomes lower than the concentration of the dichroic dye in the central portion 5C. For example, the laminate used for dry ice and snow cleaning may be at least any one of the above-mentioned first laminate, second laminate, and third laminate. That is, the step of cleaning the end face of the laminated body with dry ice and snow may be carried out after the above step of cutting the laminated body with a knife. The step of cleaning the end face of the laminated body with dry ice and snow may also be carried out after the above step of grinding the end face of the third laminated body with a knife. By cleaning with dry ice and snow, processing debris generated by cutting the laminated body and grinding the end face of the laminated body is removed. Laminates cleaned with dry ice and snow can be packaged as finished polarizers. The manufacturing method of the polarizing plate may further include a step of drying the end surface cleaned with dry ice and snow. The drying method can be warm air. The manufacturing method of the polarizing plate may also include a step of wiping off the solvent remaining on the end surface cleaned with dry ice and snow. Through these steps, it is easy to reliably remove the dichroic dye remaining on the end face of the laminate.

Another example of the method of manufacturing a polarizing plate may include: a step of producing a plurality of laminates, the plurality of laminates include a polarizing element layer 5 having the same size and laminated structure as the polarizing plate, and the polarizing element layer 5 contains a polymeric liquid crystal compound. Polymers and dichroic pigments; process of applying a solvent capable of dissolving dichroic pigments to the end surfaces of multiple overlapping laminates; process of wiping off solvent applied to the end surfaces of multiple overlapping laminates ; and a step of bundling the plurality of laminates from which the solvent has been wiped off. At least a part of the dichroic dye included in the outer peripheral portion 5P of the polarizing element layer 5 oozes out into the solvent by applying the solvent to the end surface of the laminate. By wiping off the solvent from the end face of the laminate, the dichroic dye is removed from the laminate together with the solvent. As a result, the concentration of the dichroic dye in the peripheral portion 5P becomes lower than the concentration of the dichroic dye in the central portion 5C. A plurality of laminates including the polarizing element layer 5 and having the same size and laminate structure as the polarizing plate can be the above-mentioned second laminate. The so-called plural laminates from which the solvent has been wiped off can also be referred to as completed plural polarizers. Applying the solvent to the end face of the laminate and wiping off the solvent from the end face of the laminate may be carried out after the above step of cutting the laminate with a knife. Applying the solvent to the end face of the laminate and wiping off the solvent from the end face of the laminate may also be carried out after the above step of grinding the end face of the third laminate with a knife. The method of manufacturing a polarizing plate may further include a step of drying the end faces of the plurality of laminates from which the solvent has been wiped off, before the step of bundling the plurality of laminates. By drying the end faces of the laminate, it is easy to reliably remove the dichroic dye remaining on the end faces of the laminate. The drying method can be warm air.

A plurality of the above-mentioned manufacturing methods and a plurality of the above-mentioned steps can be combined with each other.

(first protective layer 3) The first protection layer 3 protects the polarizer layer 5 (and the alignment layer 4 ), and suppresses the diffusion of the dichroic dye from the polarizer layer 5 . The first protective layer 3 may also be called a hard coat layer (surface treatment layer). The first protective layer 3 may be a cured product of ultraviolet curable resin. For example, the ultraviolet curable resin may be at least one selected from the group consisting of acrylic resin, silicone resin, polyester resin, urethane resin, amide resin, and epoxy resin. . In order to improve the mechanical strength of the first protective layer 3 , inorganic fine particles, organic fine particles, or a mixture thereof may be added to the first protective layer 3 . The first protective layer 3 can be formed on the surface of the base film by a transfer printing method. For example, the forming method of the first protective layer 3 may include: on the surface of the base film covered by the release agent, a step of forming a coating film comprising an uncured ultraviolet curable resin; A step of transferring the surface of a base film; and a step of hardening the coating film transferred to the surface of another base film by irradiation of ultraviolet rays. The base film may be a polyester-based resin film such as polyethylene terephthalate, polyethylene naphthalate, or polybutylene terephthalate.

The first protective layer 3 may also be selected from methacrylic resin films such as polymethyl methacrylate (PMMA); acrylic resin films; cellulose acetate resin films such as triacetyl cellulose and diacetyl cellulose. ; Cyclic polyolefin resin film; Polycarbonate resin film; Polypropylene resin film; Polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, etc. One of the thermoplastic resin films in the group consisting of ester-based resin films.

(alignment layer 4) The alignment layer 4 is a film containing a polymer compound, and has the function of aligning the polymerizable liquid crystal compound constituting the polarizer layer 5 in a desired direction. For example, the alignment layer 4 may be an alignment film selected from the group consisting of an alignment film containing an alignment polymer, a photo alignment film, and a groove alignment film.

The alignment polymer can be selected from polyamide having an amide bond in the molecule, gelatin having an amide bond in the molecule, polyimide having an imide bond in the molecule, and a hydrolyzate of the polyimide Polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylate At least one polymer compound in the group formed.

For example, the formation method of the alignment layer 4 may include: a step of forming a coating film comprising an alignment polymer and a solvent on the surface of the first protective layer 3, a step of removing the solvent from the coating film, and rubbing A step in which the solvent-removed coating film is treated.

The solvent used in the formation of the alignment layer 4 can be selected from water; Alcohol solvents such as methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ethyl acetate Ester solvents such as ester, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate and ethyl lactate; acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone Ketone solvents such as , methyl amyl ketone and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; tetrahydrofuran and dimethyl Ether solvents such as oxyethane; and at least one solvent selected from the group consisting of chlorinated hydrocarbon solvents such as chloroform and chlorobenzene.

The photo-alignment film includes polymers with photoreactive groups. The formation method of the photo-alignment film may include: on the surface of the first protective layer 3, a step of forming a coating film comprising a polymer or monomer with a photoreactive group and the above-mentioned solvent; ) to the step of irradiating the coating film.

The photoreactive group is a functional group that exhibits liquid crystal alignment ability by irradiating light. For example, the photoreactive group may be a functional group that induces alignment of molecules by irradiation of light. The photoreactive group may also be a functional group that causes a photoreaction (isomerization reaction, dimerization reaction, photocrosslinking reaction, or photodecomposition reaction) that becomes a source of liquid crystal alignment energy. For example, the photoreactive group may have a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond), and a carbon-carbon double bond. A functional group of at least one bond structure in the group consisting of an oxygen double bond (C=O bond).

The photoreactive group having a C=C bond may be selected from the group consisting of vinyl, polyenyl, stilbene, styrylpyridinium, styrylpyridinium, chalcone, and cinnamyl at least one of them. The photoreactive group having a C=N bond may be at least one selected from the group consisting of aromatic Schiff bases and aromatic hydrazones. The photoreactive group with N=N bond can be selected from azophenyl group, azonaphthyl group, aromatic heterocyclic azo group, disazo group, formazan group, and azobenzene-type structures. At least one of the group. The photoreactive group having a C=O bond may be at least one selected from the group consisting of benzophenone group, coumarin group, anthraquinone group and maleimide group. Polymers with photoreactive groups can also have at least a substituent.

The groove (groove) alignment film is a film with a plurality of concave-convex patterns or a plurality of grooves (grooves) formed on the surface. The polymerizable liquid crystal compound constituting the polarizer layer 5 is aligned in a predetermined direction along the concave-convex pattern or a plurality of grooves.

The method for forming the trench alignment film may include the steps of exposing the surface of the photosensitive polyimide film by using an exposure mask formed with a plurality of slits, and developing after the exposure. And rinse treatment, and the concave-convex pattern is formed on the surface of the photosensitive polyimide film. The method for forming the groove alignment film may include: forming a coating film comprising uncured ultraviolet curable resin on the surface of the plate-shaped master with grooves; a step of surface transfer; and a step of hardening the coating film transferred to the surface of the first protective layer 3 by irradiation of ultraviolet rays. The method for forming the groove alignment film may include: forming a coating film containing uncured ultraviolet curable resin on the surface of the first protective layer 3; pressing the surface of a roller having a plurality of grooves to the surface of the coating film and a step of hardening the coating film formed with grooves on the surface by irradiation of ultraviolet rays.

(polarizer layer 5) The polarizer layer 5 includes a polymer of a polymerizable liquid crystal compound and a dichroic dye. The forming method of the polarizing element layer 5 may include: a step of coating a polarizing element layer raw material comprising a polymerizable liquid crystal compound, a dichroic pigment, and a solvent on the surface of the alignment layer 4 to form a coating film; A step of polymerizing the polymerizable liquid crystal compound. For example, "the composition for forming a polarizing film" described in JP-A-2017-83843 can be used as a raw material for a polarizing element layer.

The polymerizable liquid crystal compound is a compound having a polymerizable group and exhibiting liquid crystallinity. The polymerizable group is the group that participates in the polymerization reaction. For example, the polymerizable group may be a photopolymerizable group. The photopolymerizable group may be a group that participates in a polymerization reaction using an active radical or an acid generated from a photopolymerization initiator. For example, the polymerizable group may be selected from vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, oxiranyl and at least one functional group in the group consisting of oxetanyl. The polymerizable liquid crystal compound may be thermotropic liquid crystal or lyotropic liquid crystal.

The polymerizable liquid crystal compound may be a thermotropic liquid crystal compound forming a nematic liquid crystal phase, a thermotropic liquid crystal compound forming a smectic liquid crystal phase, or a thermotropic liquid crystal compound forming a higher order smectic liquid crystal phase. The polymerizable liquid crystal compound can form a smectic B phase, a smectic D phase, a smectic E phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic I phase, a smectic J phase, or a smectic K phase. Phase or smectic L-phase thermotropic liquid crystal compound. The X-ray diffraction pattern of the polarizing element layer 5 with excellent polarization performance includes peaks of diffraction X-rays derived from higher-order structures such as hexagonal phase and crystal. The peaks of X-ray diffraction from higher-order structures may be peaks from molecularly aligned periodic structures. The periodic interval of molecular alignment can be 3-6 Å.

The polymerizable liquid crystal compound may be at least one compound represented by Chemical Formula A below. U ¹ -V ¹ -W ¹ -X ¹ -Y ¹ -X ² -Y ² -X ³ -W ² -V ² -U ² (A) X ¹ , X ² and X ³ each independently represent that they may have a substitution 1,4-phenylene group, or cyclohexane-1,4-diyl group which may have a substituent. Among them, at least one of X ¹ , X ² and X ³ is a 1,4-phenylene group which may have a substituent. -CH ₂ - constituting cyclohexane-1,4-diyl may be substituted with -O-, -S- or -NR-. R represents an alkyl group or phenyl group having 1 to 6 carbon atoms. Y ¹ and Y ² each independently represent -CH ₂ CH ₂ -, -CH ₂ O-, -COO-, -OCOO-, single bond, -N=N-, -CR ^a =CR ^b -, -C≡ C- or -CR ^a =N-. R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. U ¹ represents a hydrogen atom or a polymerizable group. U ² represents a polymerizable group. W ¹ and W ² each independently represent a single bond, -O-, -S-, -COO- or -OCOO-. V ¹ and V ² each independently represent an alkanediyl group having 1 to 20 carbon atoms which may have a substituent. -CH ₂ - constituting the alkanediyl group may also be substituted with -O-, -S- or -NH-.

The dichroic dye may be a dye having a maximum absorption wavelength (λ _MAX ) in the range of 300-700 nm. For example, the dichroic dye may be at least one dye selected from the group consisting of acridine dyes, cyanine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes. For example, the azo dye may be at least one dye selected from the group consisting of monoazo dyes, disazo dyes, trisazo dyes, tetrazo dyes and stilbene azo dyes. The polarizer layer 5 may contain two or more kinds of dichroic dyes (especially azo dyes), or three or more kinds of dichroic dyes (especially azo dyes).

For example, the azo dye may be a compound represented by Chemical Formula B below. A ¹ (-N=NA ² ) _p -N=NA ³ (B) A ¹ and A ³ each independently represent a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or a 1 group which may have a substituent Valence heterocyclic group. A ² represents an optionally substituted 1,4-phenylene group, an optionally substituted naphthalene-1,4-diyl group, or an optionally substituted divalent heterocyclic group. p represents an integer of 1-4. When p is 2 or more, a plurality of A ² may be identical to each other, and a plurality of A ² may be different from each other.

The solvent used in the raw materials for the polarizing element layer can be selected from alcohol solvents such as methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ethyl acetate Ester solvents such as ester, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate and ethyl lactate; acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone , 2-heptanone and methyl isobutyl ketone and other ketone solvents; pentane, hexane and heptane and other aliphatic hydrocarbon solvents; toluene and xylene and other aromatic hydrocarbon solvents; acetonitrile and other nitrile solvents; tetrahydrofuran and dimethoxy Ether solvents such as ethyl ethane; and at least one solvent in the group consisting of chlorine-containing solvents such as chloroform and chlorobenzene.

The raw material for a polarizing element layer may contain a polymerization initiator (photopolymerization initiator etc.). For example, the polymerization initiator may be at least one compound selected from the group consisting of benzoin compounds, benzophenone compounds, benzophenone compounds, acylphosphine oxide compounds, trisalphonium compounds, iodonium salts, and phosphonium salts.

The raw material for a polarizing element layer may further contain a sensitizer, a polymerization inhibitor, a leveling agent, and a reactive additive in addition to a polymerizable liquid crystal compound, a dichroic dye, a solvent, and a polymerization initiator.

The "photoalignment layer" described in International Publication No. 2020/122117 can be used as the alignment layer 4, and the "liquid crystal layer" described in this document can be used as the polarizer layer 5. The "photoalignment film" described in International Publication No. 2020/179864 can be used as the alignment layer 4, and the "polarizing layer" described in this document can be used as the polarizing element layer 5.

(second protective layer 6) For example, the second protective layer 6 may contain polyvinyl alcohol-based resin. For example, the polyvinyl alcohol-based resin may be selected from partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, methylol-modified polyvinyl alcohol, and at least one polyvinyl alcohol in the group consisting of amino-modified polyvinyl alcohol. The method for forming the second protective layer 6 may include: forming a coating film containing polyvinyl alcohol resin and water on the surface of the polarizer layer 5 , and drying the coating film by heating the coating film.

The second protective layer 6 can also be selected from methacrylic resin films such as polymethyl methacrylate (PMMA); acrylic resin films; cellulose acetate resin films such as triacetyl cellulose and diacetyl cellulose. ; Cyclic polyolefin resin film; Polycarbonate resin film; Polypropylene resin film; Polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, etc. One of the thermoplastic resin films in the group consisting of ester-based resin films.

The second protective layer 6 may contain a cured product of a cationic polymerizable compound such as an epoxy compound, an oxetane compound, or a vinyl compound. The second protective layer 6 may also include a cured product of a radically polymerizable compound.

(The first adhesive layer 7 and the second adhesive layer 9) Each of the first adhesive layer 7 and the second adhesive layer 9 may include (meth)acrylate compounds selected from multifunctional acrylate compounds and multifunctional methacrylate compounds; Urethane (meth)acrylate compounds such as ester compounds and multifunctional urethane methacrylate compounds; epoxy (meth)acrylate compounds such as multifunctional epoxy acrylate compounds and multifunctional epoxy methacrylate compounds Meth) acrylate compounds; carboxyl-modified epoxy acrylate compounds; carboxyl-modified epoxy methacrylate compounds; polyester acrylate compounds; polyester methacrylate compounds; epoxy compounds with epoxy groups; An oxetane compound having an oxetanyl group; and a polymer (hardened product) of at least one polymerizable compound in the group consisting of vinyl compounds. The polymerization method (curing method) of the polymerizable compound may be irradiation of light (ultraviolet rays, etc.) or heating. The unhardened first adhesive layer 7 containing a polymeric compound and a solvent can be formed on the surface of the second protective layer 6 or the retardation layer 8, or the retardation layer 8 can be formed by interposing the uncured first adhesive layer 7. Attached to the surface of the second protective layer 6 , the first adhesive layer 7 can harden immediately after attaching the retardation layer 8 . An unhardened second adhesive layer 9 containing a polymeric compound and a solvent can be formed on the surface of the retardation layer 8 or the optical compensation layer 10, and the optical compensation layer 10 can be bonded via the unhardened second adhesive layer 9 On the surface of the retardation layer 8 , the second adhesive layer 9 can be hardened immediately after laminating the optical compensation layer 10 . The composition of the first adhesive layer 7 can be the same as that of the second adhesive layer 9 . The composition of the first adhesive layer 7 may also be different from that of the second adhesive layer 9 .

(retardation layer 8 and optical compensation layer 10) The optical compensation layer 10 can also be referred to as a retardation layer different from the retardation layer 8 . For example, each of the phase difference layer 8 and the optical compensation layer 10 can be selected from the group consisting of positive A plates such as λ/4 plates and λ/2 plates, and positive C plates (photo-alignment material vertical alignment film). at least one. Each of the retardation layer 8 and the optical compensation layer 10 can also be formed by coating the above-mentioned polymerizable liquid crystal compound on an alignment layer different from the above-mentioned alignment layer 4 . The formation method of the alignment layer for forming each of the retardation layer 8 and the optical compensation layer 10 can be the same as that of the above-mentioned alignment layer 4 for the polarizer layer 5 .

(third protective layer 11) For example, the third protective layer 11 can also be selected from methacrylic resin films such as polymethyl methacrylate (PMMA); acrylic resin films; cellulose acetate films such as triacetyl cellulose and diacetyl cellulose. Resin film; cyclopolyolefin-based resin film; polycarbonate-based resin film; polypropylene-based resin film; and polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate One of the thermoplastic resin films in the group consisting of polyester resin films.

The present invention is not limited to the above-mentioned embodiments. Various modifications can be made to the present invention without departing from the gist of the present invention, and such modified examples are also included in the present invention.

The polarizing plate of the present invention may be a circular polarizing plate or an elliptical polarizing plate provided with one or more retardation layers like the above-mentioned polarizing plate 20 . The polarizing plate of the present invention may also be a linear polarizing plate without a retardation layer. [Industrial availability]

For example, the polarizing plate of one aspect of the present invention can be used for an organic EL display or a liquid crystal display.

3: The first protective layer 4: Alignment layer 5: Polarizer layer 5C: The central part of the polarizer layer 5E: The end face of the polarizer layer 5P: The outer peripheral part of the polarizer layer 6: Second protective layer 7: The first adhesive layer 8: Retardation layer 9: The second adhesive layer 10: Optical compensation layer (another retardation layer) 11: The third protective layer 20: polarizer W: The width of the outer periphery of the polarizer layer

FIG. 1 shows a cross section of a polarizing plate according to an embodiment of the present invention, and the cross section is approximately parallel to the thickness direction of the polarizing element layer (layering direction of the polarizing plate). FIG. 2 shows the surface of the polarizing element layer included in the polarizing plate according to an embodiment of the present invention, and the surface is substantially perpendicular to the thickness direction of the polarizing element layer (the lamination direction of the polarizing plate).

3: The first protective layer

4: Alignment layer

5: Polarizer layer

5C: The central part of the polarizer layer

5E: The end face of the polarizer layer

5P: The outer peripheral part of the polarizer layer

6: Second protective layer

7: The first adhesive layer

8: Retardation layer

9: The second adhesive layer

10: Optical compensation layer (another retardation layer)

11: The third protective layer

20: polarizer

Claims (17)

A polarizing plate comprising a polarizing element layer, The above-mentioned polarizer layer contains a polymer of a polymerizable liquid crystal compound and a dichroic dye, The polarizing element layer includes: an outer peripheral portion including an end surface substantially parallel to a thickness direction of the polarizing element layer, and a central portion surrounded by the outer peripheral portion, The concentration of the dichroic dye in a part or the whole of the peripheral portion is lower than the concentration of the dichroic dye in the central portion. Such as the polarizing plate of claim item 1, It has a first protective layer laminated directly or indirectly on one surface of the polarizer layer. The polarizing plate according to claim 2, wherein the first protective layer has an end surface substantially parallel to the thickness direction of the first protective layer, The end face of the first protective layer and the end face of the polarizer layer are included in the same plane. For the polarizing plate of claim 2 or 3, It has a second protective layer laminated directly or indirectly on the other surface of the polarizer layer. The polarizing plate according to claim 4, wherein the second protective layer has an end surface substantially parallel to the thickness direction of the second protective layer, The end face of the second protective layer and the end face of the polarizer layer are included in the same plane. The polarizing plate according to any one of claims 1 to 5, wherein A part or the whole of the above-mentioned end surface of the above-mentioned polarizer layer is covered with a film containing polyvinyl alcohol. The polarizing plate according to any one of claims 1 to 6, wherein The thickness of the outer peripheral portion is substantially equal to the thickness of the central portion. The polarizing plate according to any one of claims 1 to 7, wherein The polarizing plate has an end surface substantially parallel to the thickness direction of the polarizing plate, The above-mentioned end surface of the above-mentioned polarizer layer is exposed on the above-mentioned end surface of the above-mentioned polarizing plate. an image display device, It has a polarizing plate according to any one of Claims 1 to 8. A method of manufacturing a polarizing plate, which is a method of manufacturing a polarizing plate according to any one of Claims 1 to 8, which has: A step of producing a laminate comprising a polarizing element layer containing a polymer of a polymerizable liquid crystal compound and a dichroic dye; and A step of cutting the above-mentioned laminate with the above-mentioned knife after attaching a solvent capable of dissolving the above-mentioned dichroic dye to the knife, or A step of cutting the above-mentioned laminate with the above-mentioned knife while spraying a solvent capable of dissolving the above-mentioned dichroic pigment on the knife. Such as the manufacturing method of the polarizing plate in claim 10, It further includes a step of drying the cut surface of the cut laminate. A method of manufacturing a polarizing plate, which is a method of manufacturing a polarizing plate according to any one of Claims 1 to 8, which has: A step of producing a first laminate comprising a polarizing element layer, wherein the polarizing element layer contains a polymer of a polymerizable liquid crystal compound and a dichroic pigment; A step of producing a plurality of second laminates by cutting the first laminate; A step of producing a third laminate by overlapping a plurality of the above-mentioned second laminates; and A step of grinding the end surface of the third laminate with the knife while spraying a solvent capable of dissolving the dichroic pigment onto at least one of the knife and the end surface of the third laminate. The method of manufacturing a polarizing plate as claimed in item 12, It further includes the step of drying the polished end surface of the third laminate. A method of manufacturing a polarizing plate, which is a method of manufacturing a polarizing plate according to any one of Claims 1 to 8, which has: A step of producing a laminate comprising a polarizing element layer containing a polymer of a polymerizable liquid crystal compound and a dichroic dye; and A step of cleaning the above-mentioned end surface of the above-mentioned laminate with dry ice while spraying a solvent capable of dissolving the above-mentioned dichroic pigment on the end surface of the above-mentioned laminate, or A step of cleaning the above-mentioned end surface of the above-mentioned laminate with dry ice after attaching a solvent capable of dissolving the above-mentioned dichroic dye to the end surface of the above-mentioned laminate. The method of manufacturing a polarizing plate as claimed in item 14, It further includes the step of drying the washed end surface of the laminated body. A method of manufacturing a polarizing plate, which is a method of manufacturing a polarizing plate according to any one of Claims 1 to 8, which has: The step of making a plurality of laminates, the plurality of laminates include a polarizer layer with the same size and laminated structure as the above polarizer, and the polarizer layer contains a polymer of a polymerizable liquid crystal compound and a dichroic pigment; A step of applying a solvent capable of dissolving the above-mentioned dichroic pigment to the end faces of the plurality of above-mentioned laminates overlapping each other; a step of wiping off the above-mentioned solvent coated on the end faces of the plurality of above-mentioned laminates overlapping each other; and A step of bundling the plurality of laminates from which the solvent has been wiped off. The method of manufacturing a polarizing plate as claimed in item 16, It further includes a step of drying the end faces of the plurality of laminates from which the solvent has been wiped off before packaging the plural laminates.

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